THE

OLOGICAL MAGAZINE

{monthly 30mm"of (Beo logp .

WITH WHICH IS INCORPORATED

THE GEOLOGI ST .

EDITED BY

HENRY WOODWARD,LL.D.

,E.R.M.S

L ATE OF THE BRIT I SH MUSEUM OF NATURAL HISTORY ; PRE SIDENT OF THE

P ALE ONTOGRAPHICAL SOCIETY ; ETC .

AND

R. H RASTALL,

UNIVER SITY LE CTURER IN E CONOM’

IC GEOLOGY , CAMBR IDGE .

ASSISTED BY

PROFE SSOR J . W . GREGORY,D .SC . ,

F .G .S .

F . H . HATCH ,PH .D

PROFESSOR J . E . MARR , Sc .D .,RE S ,

F .G .S.

Sm JETHRO J . H . TEALL, SC .D .

,LL.D .

,

PROFESSOR W .

’

W . WATTS, SC .D . ,LL .D . , M . SC . ,

HENRY WOODS,M .A .

,F .R .S .

ARTHUR SMITH WOODWARD , LL .D . ,

VOL . LVII OF WHOLE SER

JANUARY—DECEMBER . 1920. 2 7 3 2 ae

LONDON :

DULAU co .,LTD 84—36 MARGARET STREET ,

CAVENDISH SQUARE , W . 1 .

19 20 .

XIII .

LIST OF PLATES .

Quartzite Pebbles, Oldhave n BedsCarbon iferous Fossi ls, SiamFig . 1 Lateritized Norite, Wilberforce, Sierra Leone . Fig .

9

Residual Laterite derived from Gran ite, Baoma , Sierra Leon eNew Lower Devonian Homalon o ti

Jurassic Ammonites from East AfricaMemorial Table t to Profe ssor James Nicol , AberdeenAmbulacra o f Ap atop ygus , Ol igop odia , an d young Echin o lamp asDiamond Pip es in BrazilForsterite Marble, Sleaford BayJames Hall, Alban y Museum , New York, US A .

Diop side an d MicroclineRock , Sleaford BayCretaceous Echinoidea from PersiaSp hcerocoryp he thomson i ReedFour Sp ecies o f Ethem

'

dg in a

New Ammon ite g e n us , Day icem s

Separate Foldin g Map Geology of Nin g i Hill s, Nige ria (n otnumber ed )

LIST OF ILLUSTRA TIONS IN THE TEXT

Sketch - map showin g p ositions o f sections o f strata n ear Leighton BuzzardD iagram showin g p art o f beds in the working face o f Harris’s PitD iagram of section o f Asterocem s obtusum

D iagram showin g discon tinuous siphun cular tube in a Hi ldo ceratidAmmon ite

Diagram of se ction in western face of a san d -

p it n orth side o f Mile TreeFarm

Tran sverse section of Bran ksome ChineLon g itudin al section of Branksome Chin eLong itudin al section of Alum ChineLon g itudin al section showing relation o f the o ld an d n ew valley s to the

chan g in g Shore lineDiagrammatic section showing quartzose con glomerate at Caldon LowSynop tic view o f the two interpre tations o f the section in Harris’S PitP os idon omya Becheri Bronn, var . n ov siamen sis

Fruit o f fossil Charophy te from Locle, SwitzerlandSketch -map of North Arran, showin g faults an d the gran iteSe ction from Catacol Bay ,

through Meal l n an Damh , etc . section acrossGlen Rosa

Se ctions across the valley o f the Garbh Al lt, we st of Glen RosaSection s across the valley of the Glean n EasbuigSketch - map of the Sn owdon dist-riotSection from Sn owdon to My n ydd MawrHypothetical sketch o f Sn owdon at e n d o f p re

- Glacial time s

Arvico la me li ten s is sp . n ov . Crown view o f first an d secon d right lowermolars

Homalo n otus bij’

urcatus Sp . n ov .

Sketch - map o f Castle an - Din asSection o f workings, Castle an Din as Min eElutriation curves of sediments to show mean ing of Equivalent

GradeTyp es of elutriation curves of aren aceous sedimentsDiagram Showing thickn ess o f Thanet Beds .

Provision al classification o f the fin er aren aceous sedimen tsElutriation curves o f Than et BedsGraph Showin g relation between equ1valen t grades of Thanet BedsSection along shore at Sleaford BayD iagrammatic sketch of flat surface o f dolomiteLogarithms in miles from Charlton

(mon th l y? 30 11'

rnal o f (Eco lo g y .

WITH I VHICH IS INCORPORATSD

THE G E O LO G lST .

EDITED BYHENRY WOODWARD , LL .D . ,

R . H . RASTALL ,M .A .

ASSISTED BY

PROF . J . w . GREGORY . D .so Sm JETHRO J . H . TEALL . Sc .D F .R .s .

F . H . HATCH , PH .D ., PROF . W . W . WATT S , Sc D F .R . S .

P R OF . J . E . MARR . Sc .D F .R . S HENRY WooDs , M A F .R . S .

DR . A . SM ITH WOODWARD . F .R . S .

JANUARY,19 20 .

EDITORIAL'

NOTES . 9

ORIGINAL ART ICLES .

An Inverted Mass o f Upper Cretace ous Strata near LeightonBuzzard . By F

‘

. L . KITCHEN an dJ . PRINGLE . (With 3 TextPre - Triassic Swallow - ho les in

'

Furne ss . By B . SMITHBrach iop od Nomenclature . ByS . S . BUCKMAN

On the Distribution of P roductus

humerosus . By T . F . SIBLYREPORTS AND PROCEEBINGS '

The; Pyg idium o f the Trilobite . Ge o log ical Socie '

ty o f Lon donG e o log ists Association

The Ammonite , Siphun cle . By Liverpoo l Ge o log ical SocietyA . E . TRUEMAN . (With 2 Textfigure s . )

CORRESPONDENCE .

Angra Pequena an d Subaerial J . A llan ThomsonDenudatio n . By R . F . RAND 32 E . H. Cunn in gham - CraigLONDON : DUDAD A CO . , LTD , , 34 - 36 MARGARET STREET

CAVENDISH SQUARE , W. 1 .

REVIEWSSummary of Progress o f the Geolog ical Survey

'

Haematites o f Furn e ssUn bedded Iron Ore sHaamatite s o f the Forest o f Dean

an d South Wale sRecent Geophy sical ReprintsThe Channel IslandsAntarctic Brachiop odsPe trology fo r “

Studen tsPalaeon to logy (In vertebrate )

JAMES SWIFT SONManufacture rs of Optica l and Scie ntific In strume nts ,

Co n tracto rs to all Scie n tific De p artme n ts o f H. lVl . Home

and Colo n i al and man y Fo re ign Gove rnme n ts.

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HE BRITISH FRESHWATER RHIZOPODA AND HELIOZOA .

By J . CASH an d G . H . WAILES , assisted by J . HOPKINSON ,

e tc . Vo lume IV. Supp leme n t to the Rhizopoda by G . H. WAIL ES ,

an d B ibliography by J . HOPKINSON . 8vo . pp .,

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GEOLOG I CAL”

MAGAZ INEVO LUME LVII.

No . I.— JANUARY, 1920 .

ED IT O R IAL NO TES .

“TE must begin the new y ear by congratulating ourselves that weare alive at all . At one time the outlo ok was very un

'

prorn isin g ,but prospects are now a little brighter, mainly owing to the n u

remitting exertions of many kind friends, both known an d unknown,at home and abroad, to whom the Editors tender their hearty thanksfor encouragement an d support in a time of need .

'

However,we are

n ot y et out of the wood, and it is obvious that the strictest economywill be necessary for some time to come . It may p erhap s be wellto p oint out for the guidance of our contributors some ways in whichthey can assist in the economy campaign . In the first place the costo f p roduction of p lates is now inordinately high, and it may be aswell to state definitely that the Magazine cannot afford “to publishp lates without at least a substantial contribution from the author .We therefore ask our contributors to limi t their demands in thisresp ect as much as p ossible . Again , corrections an d alterationsin typ e are now very costly , and much money could be saved if allmanuscrip ts were sent in finally corrected . Occasional printer’se rrors, though rare in our p roofs, are not wholly avoidable

,and as

to these there is nothing to be said . But it is the alterations of an dadditions to the text in p roof that make the p rinter’s bills mountup . We can assure our readers that with our p resent circulationthe monthly account for corrections is an important item in thebalance - sheet .

a as as

IT may i be p ermissible here to refer to one or two other mattersof internal politics . In the first p lace it will perhaps be noticedthat the p resent number is p rinted with a new fount of typ e , and thatthe titles of papers have beenmade rather more bold arid consp icuous .

Again, the former system of numbering the volumes by Series an d

Decades has disapp eared, having been found too cumbrous . Thevolume for 19 19 is numbered alternatively on the title - page Vol . LVIof Whole Series, and the p resent one is Vol . LVII . In futurereferences in this Magazine to back numbers before 1919 wi ll be givenby the

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year of publication only ,without Series or Decade . Most

p eop le have their bound volumes lettered simp ly 'with the y ear,an d it requires a comp licated arithmetical p rocess to discover

VOL . LVII .—NO . I .

1

2 Edi tor i a l Notes.

what is meant by ,for examp le , NS ,

Dec . V, Vol . VII . It was ouroriginal intention to continue the p resent system to the end of theSixth Decade, but on further consideration the bolder course of aclean cut app eared to have much to recommend it, an d was finallyadopted .

THE Non - ferrous Mining Committee continues to hold frequentmeetings, an d has heard a number of witnesses, who discussedp oints of interest, esp ecially in connexion with Cornish mining .

The general op inion seems to be that in most cases considerablefresh cap ital is essential for development adequate to meet modernconditions . The outcome, however, depends wholly on the futurecourse of the market for metallic tin . At present prices wolframapp ears to be entirely unpayable, and it is regrettable to hear thatthe very p romising Hemerdon mine is closed, after installing newp lant on a large scale . The directors app ear to be of op inion thatthe minimum remunerative price is about 558 . p er unit . At presentonly o n emi ne is working in the St . Ives district, namely Giew,

an d

that at a loss . It is estimated that to restart the St . Ives Consolsgroup would requi re an exp enditure of an d it is imp robablethat so much capital could be raised by private enterp rise at thistime . Mr . Oliver Wethered exp ressed the view that the productionof the known tinfields of the '

world could n ot keep pace with theincreasing demand,an d was of op inion that highp rices for tin woul d

rule for some time to come . With regard to Cornwall , he thoughtthere were p ossibilities of large p roduction, but considered some

immediate help was desirable to stimulate deve lopment and to

assist in the op ening up of new ore - bodies, for the existence of whichthere is geological evidence .9;

IT has recently been announced that the Geological Survey ofGreat Britain has been transferred from the Board of Education tothe Department of Industrial and Scientific Research ; thus thisinstitution undergoes another mutation in its variegated career .In this connexion it may be p ermissible to p oint out that thedevelopment of our mineral resources is now under the control of n oless than five Government departments . The Home Office is incharge of mines in this country the Mineral Resources Departmentformed by the Ministry of Munitions has been handed over to theBoard of Trade ; the Imp erial Mineral Resources Bureau collectsinformation with regard to the Dominions an d

,

Colonies ; theImp erial Institute, which has done admirable work on similar lines,is under the Colonial Ofii ce , while , as before stated, the GeologicalSurvey is n ow under the Department of Indus trial an d ScientificResearch . These facts suggest that there must be an immenseamount of overlap an d want of correlation in the different branches,an d that it is high time that all these scattered departments were

Edi tor ia l No tes .

"

3

welded into a coherent whole under one resp onsible head . We maybe allowed to hope that the institution of a Ministry of Mines willnot be long delay ed . When this comes to p ass it is p ossible thateconomic and app lied geology will gain some of the recognitionwhich is their due, and that the Government geologists may receivesalaries commensurate with their high scientific attainments an d

with the important character of the work so ably carried out by them .

as >xc a a at

THE water resources of Queensland obtained by boring are ofvast imp ortance to that fertile Australian State, an d exp ert testimonyupon the conditions underly ing this supp ly is of great interest notonly to those who dep end up on them for their means of irrigatingthe country , but also to engineers engaged in supp ly ing the equipmentfor this natural resource . An artesian exp ert writing on the subj ectsays : My exp eriences with the bores lead me to the followingconclusions, which have be en p roved correct by boring : Wheny ears ago artesian bores were first put down it was the custom todrill a hole an inch larger than the casing , so that the casing wouldgo down easily . This has to be done now . When another layer ofcasing had to be put in it was just lowered down to where the firstlot had struck

,and drilling continued . When the flow was struck it

came up the casing , and it also came up the space around the casingto the higher sand levels . In time this constant friction of thewater made the passage much larger, and in consequence the flowdecreased .

l

Now this escap ing of the waters to these higher sandlevels has done an immense amount of good, as it has put largesupp lies of subartesian waters where none existed before . I havegot the records of artesian bores put down which went through hugedry sand drifts: These bores have a diminished flow, but the sandbeds are now ful l of water, an d bores being put down all over themgive pumping supp lies from 10 to 20 thousand gallons p er day at

a dep th of from 80 to 200 feet . Also from these bores there is nowaste

,and it is easier and cheap er to put down twenty of them,

which will water a larger area of country and will not cost as muchmoney as the one artesian bore

as 95

MR . T . W. READER ,has been selected by the Geologists’

Association as the first recip ient of the Foulerton Award . Thesum of money which has enabled the Association to make

" thisaward is the recent generous gift

'

of Miss Foulerton , in accordancewith the wishes of her late uncle, Dr . John Foulerton , who wasfor many y ears secretary to the Association .

ORIGINAL ARTICLES.

On an In ve rte d Mass o f Up pe r Cre tace o us Strata l n e ar

Le ighto n Buz z ard, Be dfo rdshire an d o n an Ove rlap

o f the Up p e r Gault in that Ne ighbo urho o d.

By F . L . KITCHIN,M.A .

,Ph .D . ,

an d J . PRINGLE,FWG S

CONTENTS .

In troduction .

The Section .

The New Evidence.(a) Characters an d Correlation of the Gault in Mr. Gregory Harris

’

s P it.

(6) Comp ariso n with other Section s in the District.i . Sections n ear Leighton Buzzard.ii . Se ction s n e ar Shen ley Hill.

(0 ) Id'

en tification of the strata between the Si lver - san ds an d the inverted

mass in Mr . Harris’

s Pit.

(d) Re lations of Gault an d Cen oman ian at the main outcrop .

In terpretation of the Evidence.(a ) Even ts durin g Cretaceous time .

(b) Even ts durin g an d si n ce Glacial time .

Summary of con clusion s .

1 . INTRODUCTION .

MR . G . W. LAMPLUGH an d the late Mr . J . E. Walker publisheda paper in 1903 on a fossiliferous bed at the top of the Lower

Greensand,exp osed in sand -

p its at Shenley .Hill, near LeightonBuzzard .

1 The b ed in question p resented p oints‘ of considerable

lithological interest and was remarkable for its rich brachiop odfauna . Its p osition above the silver—sands of the Lower Greensand and below a capp ing of dark shaly clay ascribed by thoseobservers to the Lower Gaul t, led to the con clusion that it belongedto the top part of the Lower Greensand . The discovery of its fossilswas . con sidered

' to throw welcome light on the faunal charactersof the latest Lower Cretaceous rocks in England , rep resented inmore southern counties by relatively unfossiliferous sands .

The fauna of this bed of limestone lenticles raised questions ofmuch interest . While there was apparently an admixture of LowerCretaceous and Upp er Cretaceous sp ecies, a considerable numbero f the fossils p resent in the bed constituted an association of sp eciesknown in En gland '

o n ly from the'

lowest part of the varian s zone,the basal Cenomanian as understood in this country . Such werethe large form of Terebratula bip licata J . Sow . ,

T . ovata J . Sow . ,

Terebrirostra lyra (J . Rhyn chon e lla grasian a d’

Orb . , and Rh.

dimidiata (J . also the echinoids Cardiaster latissimus AgCatop ygus co lumbarius Lam . , Echin obrissus lacun osus Go ldf. ,

an d

Pyrin a laevis Ag . These and other elements of the fauna app earedto contradict the interpretation offered by Messrs . Lamplugh an d

1 G. W. Lamp lugh J . F Walker. A Fossiliferous Ban d at the topo f the Lower Green san d near Leighton Buzzard Quart . Journ . Geo l l So c. ,

vo l . l ix ,

‘

1903, p . 234 .

I n ver ted Mass of Upp er Cr etaceou s Stra ta . 5

Walker, whose reading of the facts imp lied an anomaly so arrestingas to make further investigation desirable . “

Nevertheless , thoseauthors were more impressed by the stratigraphical evidence , as

understood by them,an d remained convinced that the bed occup ied

a normal position below the .Gault . They met the difficulty byexplanations which we have always considered to be inadequate ,1while they treated as so - called varieties some of the specieswhich app eared to occur so far below their usual horizon . Argu ingfrom stratigraphical inferences, they claimed to demonstrate thatthese sp ecies in reality made a much earlier app earance and possesseda much lon ger vertical range than had p reviously been suspected .

We need make no lengthy comment here on this manner ofdealing with the p alaeontological asp ects of the bed but we desireto “record that from the first we have entirely disagreed with theinterpretation given . It has always appeared clear to us that if thebed contains both derived an d indigenous fossils its geologi cal agemust be that of its latest sp ecies . To assume such an earlyappearance and long p ersistence for the particular assemblage ofbrachiopods an d echinoids mention ed, has always seemed to us tobe making “

an arbitrary use of the fossil - evidence . Some biologicalconsiderations which are in conflict with the assumption need n ot

be entered into here . The zonal significan ce of these fossils had beenfirmly established by the well - known facts of their restrictedoccurrence bo th in this country and on the Continent . Hence itappeared a hazardous proceeding to ignore the indications theyafforded and to p lace more reliance on stratigraphical appearances .

In subsequent y ears the above - mentioned authors collectedadditional fossils from the limestone - lenticles with brachi opods,resulting in further support for our op inion that the true p ositionof the bed is at the base of the Cenomanian . Mr . H. Woods haskindly communicated to us the names of some species represen tedin the collection obtained by Mr . Walker

,now p reserved in the

Sedgwick Museum, Cambridge . They include the brachyurouscrustacean Cyphon otus in certas Bell, first described “ from the so

called Upper Greensand of Horningsham ,Wiltshire . The type

p robably came from some exposure in the basal part of theCenomanian, at which horizon the sp ecies is found at other localitiesin Wiltshire an d in Somerset . This fossil also Occurs in theCambridge Greensand . Mr . Woods p oints out to us that n o earliersp ecies of this genus is known . The lamellibranchs at Cambridgeinclude Pecten (Camp ton ectes) curvatus Gein itz , which occurs in theUpp er Greensand of Great Haldon an d in the Chloritic Marl , an d

Cyp rimeria (Cyclorisma) rotomagen sis a sp ecies of thebasal Cenomanian of Wiltshire . Among the lamellibranchs foundin the limestone by Mr . Lamp lugh and p resented by him to theGeological Survey occurs Isoarca obesa is not knownelsewhere from below the Chloritic Marl . We have ourselves collected

1 Op . Cit", PP. 247—9 .

6 F. L. Ki tchi n an d J . Pr i n g le

Lima g lobosa J . de C. Sow.,the typ e of which came from the Chloritic

Marl . This sp ecies has also been recorded from lower horizons,

but has not been found below the Gault .After the publication of the account of th e section, Mr . Lamplughcollected some fossils from an inconstant lay er of green sand, attainingin one place 5 feet in thickness , found to be intercalated betweenthe limestone - lenticles with brachiop ods and the Gault above .The sp ecimens comp rised nothing to indicate a Lower Greensandor Lower Gault age , but Mr . Lamp lugh was nevertheless inclinedto correlate the dep osit with the mammillalus bed at the base o fthe Gault .

ll These fossils included well - develop ed valves of Ostreavesicularis Lam . ,

such as are found in the zone of Pecten asp er

Lam . ;2

also Ostrea can aliculata (J . a sp ecies whi ch occursmuch more commonly above the Gault than below it . There werenumerous specimens of Serp ula an tiquata J . de C. Sow.

,a common

fossil in the Pecten asp er zone of Wiltshire . A few associatedcirrip ede

~remain s were later studied by Mr . T . H. Withers, whokindly furnished us with some notes upon them . He rep orted thata scutum an d a carina must be referred to Po llicip es g laber F . A .

Roem . , an d that agreement is closest with specimens from theChalk Marl . The carina has a narrower base than that of P . unguisJ . de C. Sow. , from

' the Gault of Folkestone . Another sp ecimenis a scutum which may best be compared with Pycn olep as rigidus

(J . de C. although it is in some respects rathermore advancedin certain characters than the typ ical valves of that species .

P . rig idus occurs in the Gault, an d Mr . Withers believes that themore advanced evolutionary characters shown by the valves fromShenley Hill indicate a later geological age . He p oints out thatnothing is known from below the Gault with whi ch an y of theseremains can be compared

,an d he considers that they furnish evidencethat the sand in which they occurred is newer than the Gault .

It is imp ortant when c onsidering this disputed question of ageto look into the literature dealing with the faunas of the zones justp rior to the mammi llatus bed, as develop ed on the Continent thatis to say , the Belemn ites strombechi beds in Brunswick (with the zoneof Leymeriella tardefurcata at the top ) an d the Clansay es zone ofSouth - Eastern France . It becomes more than ever clear that thelife of that time resembles in no manner that of the brachiop odbed at Shenley Hill, supp osed to be of comparable age . Indeedthis bed furnishes such strong faunal links with the Cornstonesof Wiltshire an d contiguous strata 3 as

,in our op 1n 10 n ,

to leave no1 Excursion to Leighton Buzzard Proc . Geol . Assoc . , vo l . xx, p t. vi ,

1908 , p . 475 .

H. Woods, M on ograp h of the Cr etaceous Lamel l ibran chia of En g lan d,Pal . So c. , vo l . ii , p t . ix, 19 13,

figs . 143—5 , p . 367 .

‘3 A . J. Jukes - Brown e, The Cr etaceous Rocks of Br ita in,vol . ii , The Lower

an d Middle Chalk of En glan d ”

(Mem . Geol . 1903, p . 148. A . J .Jukes - Brown e St J. Soan es , The Upp er Green san d an d Chloritic Marl ofMere an d Maiden Bradley , in Wiltshire Quart. Journ . Geol. Soc vo l . lvi i ,

https://www.forgottenbooks.com/join

- F. L . Ki tchin an d J . Pr i n g le

l M lLE

FIG. 1 .—Sketch - map to show the -

p osition s of the section s described . Themap is adap ted from the 1 in . Ordn ance Survey map . The numbersin di cate the p osition o f localitie s re ferred to in the text. The shaded patchat locali ty No . 5 represen ts the estimated former exten sion of the invertedmass of strata in worked - out areas in the sand -

pits.

I n ver ted Mass of Upp er Cr etaceou s Strata . 9

2 . THE SECTION .

The only section showing all the above relationships at the p resenttime is that exp osed in the sand -

p it of Mr . Gregory Harris (No .

to whose kindness we are indebted for p ermission to collect at thatlocality . The main features of this striking exposure have beendescribed by Mr . Lamplugh , whose account of the strata may besummarized as follows

,from his descrip tion of the succession seen

at the northern end of the p it (op . cit .,Fig . 3

,p .

In descending order, below 1 foot of soilA . Bluish grey Boulder clayB . Gault : bluish -

grey shaly clay above, dark blue belowC. Irregular ban d o f 1ron -

gritD . Ochreous or green ish y ellow loamy sand, grit, an d

breccia ; rep laced here an d there by lenticles Of p aleflesh coloured or yellowish gritty limeston e, full Of fossils[the brachiopod bed] .

E . Undulatin g 1ron grit bandF. Greyish loamy greensand, with clay ey streaksan d lenticles

o f p ebbly grit 2—3 feet.“Lenticles of dark red an d Ochreous iron -

grit,.

with smallincluded n odules of san dy pyritous clay ston e streaksof fuller’s earth, dark clay ey green sand, an d ochreousloam below ; forming a well defined band capping the“silver sands l —l é feet.

H. Silver sands ,” strongly cross bedded 10 - 15 ft . seen.Mr . Lamplugh gave a full account of the litho logical c haracters

Of beds D and H,- which

,with the intervening strata,

he ascribedto the Lower Greensand . He also dealt at some length with thebands

,described by him as iron -

grit C an d E . The section asexposed in October, 1918, was substantially the same as in 1903,though during the working back of the p it into the slop e of the hillthe thickness of the Gault had increased to about 10 feet . The

Boulder - clay on the other hand had become reduced in thickness .

Early in 1919 an extensive mass of Gault Clay slipp ed down intothe p it '

and obliterated the whole exp osure ; but during the pastsummer the work “of re excavation has p roceeded rapidly ,

so thatthe section can again be studied at the southern end of the p it .

A result of the slip was to render the Gault accessible for examin ationup to about 18 feet from its base, where it now shows a cappin g of

Drift so inconsiderable as to be scarcely distinguishable from the soil .A first glance at the section shows an apparent continuity withinthe series of beds situated above the silver - sands an d below the

Drift . These s trata are separated from the cross - bedded sands.

below by a well - marked p lane of division, having the app earance.of an unconformity . Mr . Lamp lugh drew attention to this line ofdemarcation

,but ascribed to it a mi nor imp ortance . He wrote :

This line of j unction seems to form a definite floor an d to imp lysome degree of erosion an d unconformity . Yet in a mass so

1 The numbers thus quoted in p arentheses are the re ference n umbers showingthe position of localities on the sketch -map ,

Fi g . 1 .

10 E. L. Ki tchi n an d J . Pr i n g le

irregularly bedded as the Lower Greensand such appearances are

n ot unusual an d need n ot necessarily denote anything more thanlocal erosion and rearrangement . ” 1 We believe this suggestedinterpretation of the break to be correct .

0

Continued excavation during the p eriod covering our Visits hasshown much y ariability in the character an d thickness of bedsD

,F

,and G. Bed F may be absent, an d G may become locally

N

0 3 2 3 7 5 217M

FIG . 2 .— Diagram to illustrate a part Of the beds seen in the working - face of

Harris’s Pit, Shenley Hill.The represen tation is g iven in simp lest diagram form . It reproduces

a p art o f the section actually seen, where the relation s of the beds_

D an d

are less con fused than is frequently the case. The clayey sand F i s presen there in fuller developmen t than in other parts o f the section exposed at

the same time, where the in verted Gault Clay approached closer to the topo f the silver - sands an d the material o f bed D1 was more conti nuous an dwas in p laces in contact with the san d~bed G.

The le tters are those used by Mr. Lamp lugh to di stin guish the successivebeds . The le n ticular masses of Mr. Lamp lugh

’

s bed D are here markedD1 an d D2 for the purp ose of distinction. Accordi n g to the readin g of theeviden ce adop ted in this p ap er the age an d relation s of the strata are asfollowsB . In verted top part o f the Up p er Gault of the neighbourhood. On ly

a p ortion o f the in verted mass is shown .

C an d E. Irregular ban ds of limonite - ironstone, develop ed alon g. the

surfaces of stratigraphical discon tinuity an d those of more re ady p ermeabi li tycaused by di sturban ce o f the strata . Where the topmost ban d separatesthe Gault from the limeston e - len ticleD2 it occup ies a surface of n on - sequen ce.D1 . Remn an ts of the basal bed o f the Up per Gault in s1tu, resti n g

un con formably upon the Lowe r Green san d .

D2 . In verted len ticular limeston e - mass with brachiop ods, a remnan t o f

the basal bed of the Cen oman ian stage formerly pre sen t in the n e ighbourhood .,F. Imp erfectly bedded clay ey san d Of the Lower Green san d, o f p re

tardefurcata'

age .

G. We ll - bedded fin e san d with thin len ticles o f carbon aceous clay an dlign ite at the base Lower Green san dH. False - bedded silver - san d o f the Lower Green san d ; on ly the

up per p art shown.

1 Op . on; 1903, p . 239 .

In verted Mass of Upp er Cr etaceou s Strata . 1 1

reduced to a few inches in thickness, while the two may be observedto swell out, only a few yards away ,

to a thickness of fully 4 feet .The app earance of inconstancy in the strata between the silversands and the Gault Clay is increased by the lenticular charactero f the variable masses forming bed D, p resent in one part of thesection whi le absent in another . (Se e Fig .

We have never seen the dark—red an d ochreous iron -

grit inbed G,described by. Mr . Lamp lugh as occurring in lenticles . When

e ver examined by us bed G has consisted of horizontally beddedgrey , bla’ck an d green - streaked carbonaceous an d clay ey sandin thi n layers, with purer streaks showing a closer app roach to thecharacter of the underly ing silver - sand

,from whi ch the sandy

constituents of the bed have apparently been derived . The sando f this bed , particularly in some of the lay ers , is of an excep tionallyfin e

,smooth texture . At the base

,immediately overlying the silver

sands there are local patches of carbonaceous clay with muchlignite . These are about 2 inches in greatest thickness an d maya ttain a length of 5 feet . We have obtained flat p ieces. of ligniteup to 6 inches in length from this basal lay er of bed G . An in

constant seam of limonite—ironstone,vary ing from 1 to 2 inches in

thi ckness,is p resent at the junction of beds G an d F . It occurs

in the form of isolated lenticles vary ing from 2 to 9 feet in length .

The thin ironstone - bands (C an d E) , following an undulatingcourse above and below the lenticular masses of bed D,

displaymuch irregularity . Mr . Lamp lugh has described how they sometimesapp roach one another, so that they almost meet . We have seenthem again and again envelop ing the lenticles of limestone an d

brecciated material of bed D and becoming actually confluent .The lenticular enclosures thus formed may occasionally includea little of the sand of bed F . We have noticed also that the lowerironstone - band

,E, frequently gives off branches which pass down

obliquely into bed F , an d sometimes become j oined to a thinnerinconstant lay er of similar ironstone which occurs here an d therewith almost horizontal disp osition within that bed (see Fig .

From these relations we conclude that the bands of ironstone formn o ,o rigin al part of the beds with which they are now incorporated ,but are of subsequent development . As will p resently be shown ,no other conclusion is p ossible in view of the fact that beds D an d Fare not in normal sequence an d are of widely different age . Thenature of bed D

_

alone is such as to disp rove the contemporaneouso rigin of the ironstone - bands . The bands themselves , occupy inga p osition along the surfaces of more ready permeability ,

are com

p osed o f limonite , somewhat cavernous in p laces , with a vary ingamount of included sand . Where they occur within a sand , as inbed F

,they may contain much of the same material . A sp ecimen

taken from between a limestone - lenticle of bed D and the GaultClay above

,contains scattered sand—grains no more numerous than

the grains within the limestone, which the limonite has partly

1 2 F. L. Ki tchin an d J . Pr i n g le

rep laced . But the purity of the limonite varies much , even withinthe sandy strata . We do n ot consider that Mr . Lamp lugh’

s termiron -

grit as app lied to these bands, is quite happily chosen .

Bed D,which contains the lenticles of brachiop od—limestone, is

of a comp lex character ; - it may be more convenien tly discussedon a later page in the light of information obtained at other sections .

Its confused aspect is the result of a remarkable collocation o f

heterochronous elements . While the lenticles of brachi opodlimestone belong to the basal bed of the Chalk, there are otherlenticles of sandy clay ,

often with rounded grit - grains and p ebbles,which contain angular or subangular fragments and roundedp ebbles of ironstone ; these masses

,together with some patches

and streaks of y ellowish sandy and earthy - looking clay ,are remnants.

of the basal bed of the Upp er Gaul t . The separate lenticles of diverseorigin an d age are brought into juxtaposition in such a mann er asto app ear as if they had originally occup ied the same general planebelow the base of the Gault Clay in this section ; and they haveacquired a certain spurious resemblance to one another as a resultof secondary ferruginous staining .

Other p oints must be noted here, the significance of which willapp ear in our further discussion of this comp osite bed . In th elenticles and streaks belonging to the base of the Upper Gault wehave seen occasional small white calcareous nodul es . In one of theseirregular streaks we found a flat pale - brown clay stone nodule , thesource ofwhich

,in a stratum of pre - in terrup tus age , can be tracedin another section . The lowest two or three inches of the Gault

Clay , in contact with the limonite - sheet overly ing bed D,are in some

p arts shaly an d fissile in the horizontal direction, and are stainedto a reddish hue .

3. THE NEW EVIDENCE .

Neighbouring exp osures, where the lenticles of brachi opod- limestone are absent, reveal vary ing stratigraphical relationshipswhich have an imp ortant bearing on the interp retation o f the sectionat Harris ’s Pit . The Gault Clay in these other sections, whenpresent, is not the same Gault, either lithologically or palaeon tologically ,

as that forming the 18 ft . mass above the brachiopodbed in Harris ’s Pit. Indeed

,the clay an d the brachiopod - limestone

of bed D in that section are quite local an d narrowly circumscribedin

' their occurrence, a p oint whi ch we shall p resently emphasize .

We soon recognized that an imp ortant break in . the successionoccurs there below the brachiopod - limestone .The fossiliferous limestone - lenticles, which had already received

so much attention,seemed to speak for themselves an d to requi re

no further palaeontological study ; hence it app eared advisable inthe first p lace to examine the credentials of the supposed LowerGault above . Fossils were collected from it at successive levels,and a comparison was made with the Gault seen in normal position

In veivfed Mass of Upp er Cr etaceou s Strata .

above the Lower Greensand in p its near Leighton Buzzard , an d alsoi n p its adjacent to Harris’s at Shenley Hill, as well as in othersfurther away to the east an d west of the hill . The study of theses ections enabled us

,at the same time

,to identify the beds betweenthe silver - sand and the brachiop od - limestone at Harris’s Pit .

Finally , information was sought as to the succession of beds betweenthe Gault an d the Chalk Marl along the base of the Chalk escarpment,some miles to the east and south - east .

A . CHARACTERS AND CORRELATION OF THE GAULT IN

MR . GREGORY HARRIs’s PIT .

It is a matter of surprise to us that this clay has ever been mistaken for Lower Gault . Its lowest part shows a p ronounced marlycharacter, an d differs from the true Lower Gault of the districtby the absence of sand an d the rarity of glauconite it y ields noneof the ammon ites of the Lower Gault

,but contains species

characteristic of the rostratus zone .To confine attention first of all to the lowest 8 feet . The well

bedded rock above the lowest few inches has a blocky or subconchoidal fracture it is of a very dark -

greenish grey hue when wet ,but dries to a much paler colour . Though strongly argillaceous ,it contains a considerable p rop ortion of carbonate of lime an d itshows minute glistening sp ecks, which at first suggest that it issomewhat . micaceous . This app earance is due to tin y flakes ofcarbonate of lime, p robably derived from the thin friable shells ofa sp ecies of An omia .

With the excep tion of Be lemn ites min imus List . , which is foundfairly abundantly a short distance above the base, fossils are note asily obtainable in a state fit for identification . In ocerarnus is

not uncommon, an d there are apparently at least two species, oneo f which is a flattened expanded form suggestive of I cripp si

Mantell . Neither I . con cen tricus Park . nor I . sulcatus Park . has beenfound in the lowest 8 feet, although prolonged searches have beenmade . ' The p resence of small impressions of the characteristicallyornamented Nauti lus deslongchamp sianus, d

’

Orb .,indicates a

p osition in the rostratus zone or higher . This sp ecies has b eenrecorded from the Upp er Greensand of Wiltshire (rostratus beds an dPecten asp er beds) , but it is more distinctive of the Chalk Marl .Ammonites occur in a band which

,in difieren t parts of the section,

varies in position from 2 feet to about 4 feet above the base of theclay . They are p oorly p reserved, in a comp ressed condition , oftenconsisting of little more than brownish rusty films on the beddingsurfaces

,nevertheless

, many show p lainly the main features . Thecommonest form i s closely comparable with well known specimensfrom the sandstones (rostratus zone) of the Upp er Greensand ofDevizes an d of the Undercliff

,Isle of Wight, variously named in

museum collections as Hcp li tes auritas (J . Sow . H. cati llus (J . de C.

Sow . or H. auritus var . cati llus .

1 4 F. L . Ki tchi n an d J . Pr i n g le

These well - known ammonites have not been adequately studied,

an d their relationship s remain to be ascertained . They are discoidin form

,an d are characterized by strongly curved ribs and the loss

of these ornaments in the later growth - stages, durin g which, however,traces of the flattened

,swollen rib - endings on either side of

the smooth, narrow p eripheral area continue to be shown . Thenaming of these distinctive forms is of little imp ortance in the presentconnexion it is sufficient to say that they are members of an easil yrecognizable hop litid group which have reached an evolutionarystage characterized by degeneration of the sculp tural features . The

significant p oint is that they give us an imp ortant datum - line .A sp ecimen of one Of them from the Upp er Greensand near Devizeshas been kindly examined for us by Dr . B . Pop e Bartlett, who ,after discussing the matter with Mr . J . Soanes

,has expressed the

op inion that it came from a p osition about 60 to 80 feet below the

base of the Cenomanian stage . This is in the rostratus zone, andthe similar sp ecimens from the Isle of Wight came from the sandstones underly ing the Chert Beds on a corresp onding horizon .

Among other fossils found in the lower part Of the clay at thelocality we are discussing are Nucula p ectinata J . Sow .

,Pecteii

(Syn cyclon ema) orbicularis J . Sow .

, and Scalaria dup in ian a

d?

Orb . ; but these are valueless/ in settling the question of age ,since their range extends up from the Gault into an d above the zoneOf Beef-en asp er . At about 8 to 10 feet above the base of the clayfurther ammonites were found . These include —a Hop lites of thetuberculatus group ,

and another well - tuberculated sp ecies showingsmooth late growth—stages also a large involute hop litid of flatteneddiscoid form

,devoid of ornamentation an d with narrow concave

peripheral area . This app ears to represent an advanced evolutionarystage in on e of the several series whose members are commonlyunited under the favourite collective name H. sp lenden s . At thislevel and in the overly ing part of the clay there occur large crushedexamp les of In oceramus sulcatus, Park ,

a fact of much significance .At about 15 to 17 feet above the base these In ocerami are associatedwith numerous ammonites

,including an undescribed Sckloen backia,

characteristic of the rostratus beds, Sckloen backia varicosa (J . de C.

Sow . ) Hysterocei as ofHyatt], and several species ofMorton icei as

(the keeled ammonites of the rostratus group ,sen sa lato ) , including

at least one belonging to the narrower group of M . inflatum

(J . This association Of forms, particularly the abundanceof In oceramus sulcatus an d Schloenbach-ia varicosa, p oints to a

position in the rostratus zone corresp onding with Price’s Bed IX at

Folkestone . 1 This upp er part Of the clay is rather more limy , an don dry ing becomes paler in colour than the lower part . The factthat the Upper Gaul t along parts of the Bedfordshire outcrop showsresemblance to the '

ChalkMarl has been frequently commented on .

1 F. G. Hilton Price, A Mon ograp h of the Gau lt, London , 1880 , p . 20 .

the Gault o f Folkestone Quart. Journ . Geol. Soc. , vol . xxx, 1874, p . 351.

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1 6 Bern ard Smi th— Pr e - Tr iassi c Swa l low - ho les .

Pre - Triassic Swallow - ho le s in the Haematite District Of

Furn e ss, Lan e s a Gl imp se o f an An c ie n t Lan dscap e .

By BERNARD SMITH,M.A .

,

(Published by p ermission of the Director of the Geo logica l Survey . )

APOINT of economic imp ortance, as well as scientific interest

,

has been brought out by a study of the occurrences ofhaematite in the Furness district of Lancashire and the neighbour ingshores of the River Duddon in the Millom district of Cumberlandnamely ,

that the origin and distribution Of the ore - bodies , knownas sops is due

,in large measure, to the physiographi cal con

dition s that existed in this area in post - Carboniferous but preNew Red times . Future exp lorations for these p rofitable ore - bodiesmay be gui ded by a true app reciation of the conditions of formation

,

which are discussed, in somewhat scattered '

form,in the recently

p ublished Geological Survey Memoir 1 on the Haematites of WestCumberland, Lancashire, an d the Lake DistrictThe following is a more connected resumé of the events that

gave rise to the sops and the reasons for their restricted occurrence .We may preface

'

our remarks by stating that '

(1 ) the haematitefound in the Carboniferous Limestone, both in Cumberland and

Furness, is due to a metasomatic alteration of the Limestone,p resumably by the descent Of iron - bearing solutions stored in theNew Red beds that overspread the Carboniferous rocks ; and (2)sops may be defined as bodies of ore, circular to oval in form,

an d narrowing downwards irregularly like deep basins or pocketsin limestone .It app ears that in p re

- New Red times the main mass Of

Carboniferous Limestone formed a widesp read p lateau extendingfrom near Kirksanton

,north - west of Millom in Cumberland, east

ward to near Lindal - in - Furness,and was dominated on the south

by a northward - facing escarpment of Yoredale Beds . South—westO f Dalton - in - Furness the escarpment loop ed southward to nearYarlside and Stank, as a sharp V - shaped notch , the eastern wall ofwhich was a pre - NewRed faul t - scarp trending from north to south .

At the present day swallow - holes and caverns are abundant onsuch limestone p lateaux, an d as fast as the swallows go out ofcommi ssion

,or the cavern—roofs collap se, they become choked with

débris, mostly of an angular an d open character, an d occasionallyroofed with turf . SO also in this case swallows were formed , an dwhen a hole ceased to serve as an open conduit, material fallingfrom the walls filled the bottom with coarse limestone débris, an dincluded masses of limestone - shales . Disintegrated shale an d mud,

washed in,formed a rough lining to the whole mass, an d in some

cases formed a clay ey plug at the bottom . The foot of the escarpm ent, also

,became the dep ository of screes or brockrams as

1 Sp ecial Reports on the Min eral Resources of Great Britain, vo l . vii i , 19 19 .

Ber n ard Smi th—Pre - Tr iassi c Swa l low - ho les . 1 7

the escarpment slowly receded under the action of weatheringagents .

In New Red times both the ' plateau and escarpment were overspread by characteristic dep osits Of dolomitic limestone an d brecci’as(both local) , red sands, clays, and shales , relics Of which still survivein several p laces, even where there has been great denudation .

In the Newton and Yarlside Mine,in the V - shap ed notch above

mentioned , the old pre - Triassic fa1ilt- escarpment has the irregularo utline of a p resent - day limestone cliff, with the NewRed Sandstonestill banked against it .At some p ost - Triassic date the area was upheaved

,faulted

,and

subj ected to denudation .

Since the up lift the Yo redale Beds have been worn back bye rosion almost 2 miles to their p resent position near Adgarley and

Little Urswick . Farther south they have retreated less ., T owards

the Duddon shores they are faulted down beneath New Red Sandstone an d do not appear at the surface .The up lift further resulted in the downward movement Of iron-bearing waters, which attacked the limestone - breccias in the swallowsan d caverns, or the limestone along faults and j oints .

The mineralizing solutions, entering from above , were concentratedchiefly up on the limestone - breccias, which by '

n ature are p eculiarlyvulnerable . As the alteration of the limestone fragments p rogressedthe masses of newly formed ore packed together and led to thecollap se of the roof and let in the overly ing New Red sands an d

loams In jumbled masses . This episode 1s recorded in the irregularp ockets Of such material that are found in the ore of the Park an dRoanheadMines .

1

That the above is probably the true story receives confirmationfrom the following facts (i) After removal Of the ore the limestonewalls

,in some cases, show a smoothing that is characteristic of the

action Of water, an d presumably was effected before the ore wasformed . (ii) The sops are lined with hunger and muc

The former is partly comp osed of weathered shale like that interbedded with the limestone, while the muck is probably derivedfrom the ore itself . (iii) Patches of limestone shales are foundembedded sp oradically in the pure ore . (iv) The ore in the centreOf each sop is good soft pick - ore , in small fragments, just such as

would be formed from a‘ loose breccia that packed together during

alteration . (v) Lastly , a mass at least 122 feet in thickn ess nearits centre

,composed of choco late coloured clay like a cave earth, and

containing many subangular waterworn fragments of limestone, hasbeen found recently , filling the bottom of theNigel Pit so p atRoanhead, ben eath the main mass of ore . It also contains small sandstonefragments and patches of hunger and muck .

In Furness,therefo re, the area in which sops may be expected

1 Summary o f Progress for 19 16 ‘Mem. Geol. Surv . , 19 17, pp . 9—10 .

VOL . LVII .—No . I .

2

1 8 S. S. Buc/crn an — The Gen o typ e of Sp i r ifer .

to occur is constituted by the limestone - p lateau, some 7 to 8 squaremiles in extent, north of the Old Yoredale escarpment . 1 To thesouth an d east of the escarpment the ore occurs usually only invein - like form

,an d the existence of large bodies of ore becomes less

p robable with increased distance from the escarpment and a corresp on din gly increased thickness Of cover Of Yoredale Beds

,which

acted as a screen between the iron - bearing solutions and the limestone .Ore in sop

- like form is also likely to occur in the Limestonebeneath the Duddon Sands north of San dscale , and to a less extentperhap s in the Millom area no rth of Haverigg .

In the sop area (excluding the Duddon shores , where exp lorationis proceeding ) the ore - bodies usually come up to the surface , or tothe base of the Glacial drift, and presumably most of these (somewhere near 100) have been located . Some

,however

, may haveremained undetected in the belt where both Sop s an d

“ veinsoccur

.

most freely— i e . on the line of the foot Of the Old Yoredale

escarpment from the south - east of Dalton as far as the LindalWhinfie ld district . Moreover, some of the Old mines might p ay toreopen

,for they were abandoned owing to trouble with water or

p oor demand for ore .In the area where the vein - like ore - body is p redominant, south

and east of the Old escarpment , deep cross - cuts may p rove reserves,as in one case where not only is an old vein being worked in depthbut new ore - bodies have been discovered .

Brachio p o d Nom e n clature : TheG e n o ty p e o f Sp ir ife r

By S. S. BUCKMAN .

N this Magazine, August, 1919 , p . 371 , Dr . J . Allan Thom sonhas an article on the a bove subj ect

,in which he app ears to beexp ress ing the hop e that Sp irifer cusp idatus may not be taken as

the genotyp e Of Sp irifer, though he thinks that certain rules ofzoological nomenclature drive him to that con clusIOn .

It is all very well for zoologists to draw up rules with regard tonomenclature

,but they can get tied up with them an d then fresh

rules must be made to interp ret the former, which may go on ad

i nfin itum. Nowadays in science as in p olitics we are hung up withtoo many rules . Rules breed rules

,an d the worse they are the

more they breed . SO the fewer rules the better But there is o n e

rul e necessary in nomenclature— read the original diagnosis an d tryto give effect to the author’s intention, so as to fit it to modernrequi rements .

Why is Sp . cusp idatus to be the genotype of Sp irifer Becausei t is the first sp ecies mentioned .

“ That may be denied, but if it were1 The course of this escarpmen t is shown in p l . iii Of the memoir.

S . S . Buclcman —The Gen o typ e of Sp i r ifer . 1 9

true the first species rule is itself an absurdity . It is just a contrivan ce to save a compiler’s time

,relieving him of the necessity

or reading an original diagnosis to find out an author’s meaning .

When the first sp ecies has Obtained its position ,not for a zoo logical

reason, but for an alphabetical, a geological, or a typographicalreason, its selection as genotyp e may result in an absurdity— itmay fail to fill the author ’s diagnosis .

It may be urged that Sp . cusp idatus is the monotype of .Sp irifer .

That I challenge . I would argue that the descrip tion of S . cusp i

datus is a separate act, not a part of Sowerby ’

s generic diagnosis .

That is complete in itself . Supposing that the descrip tion ofS . cusp i

datus had been written by another author,then S . cusp idatuswoul d n ot be the genotyp e of Sp irifer. Why should it be so because

the descrip tion was written by Sowerby ?The diagnosis of Sp irifer (Min . Con ch , 11, Feb . , 1816, p . 41 )says, The shells of this genus that is plural

,that rules Out

a monotype ; the genus is founded on several species which are

gen osyn typ es . This is s hown further : “ '

I think this genus willcomprehend nearly all the shells retained as Terebratula by Lamarck‘which have a triangular foramen The several individualsin which I have discovered spiral appendages (he mention s Derbyshire, Irish , and Van Diemen ’

s Land sp ecimens) bear a considerablen atural affinity to each other, from which circumstance we '

mayventure to p lace many analogous Sp ecies in this genus, althoughtheir interior has not been ful ly exposed .

” That is what - he has

done with S . cusp idatus he has p laced it in Sp irifer on sufferance;as an analogous species

,for he expressly says (p . I have not

discovered the sp iral app en dages [of S . cusp idatus] . That excludesit effectually as the genotype . He p laced it in Sp irifer by intui tion :it had the triangular foramen . It was a case of typographicalnecessity . His material of Sp irifer with the sp irals discovered washeld up by the Linnean Society but the plate of S . cusp idatus wasready . It could not be p laced in Terebratula ; it was Sp irifer bypresumption if n ot by proo f . An y one who has had to draw up listso f sp ecies an d assign them to new genera will have been confrontedwith the same difficulty an d have commi tted a simi lar act .

In cho osing a lectotyp e of Sp irifer out of these species of Derbyshire, etc . , shells, consideration should be given to Sowerby

’

s

further writings . First is hi s description of S . cusp idatus, say ingSp iral appendages may be seen in An omia trigon alis ofMartin .

That is the first sp ecies mentioned . Then in 1818 was publishedSowerby

’

s paper in the Linnean Transactions, vol . xii, wherein hefigures Terebratula striata showing sp irals . But in his descriptiono f S . trigon alis (M.C. ii , p l . cclxiii, p . 1 17) he admits that he had .

confounded it with An omia striata of Martin in the LinneanTransactions Evidently he had discovered this mistake afterthe reading of his paper to the Linnean (December, 1814) and beforethe publication of his description of S . cusp idatus (February ,

20 fi rofessor T. Fran kl i n Sibly

but was unable to alter the name in the Linnean paper, for it wouldhave involved too much exp lanation . Because, evidently , fig. 1 ,pl . xxviii, Of the Linnean Trans . is a syn thetograph— the details

of the coils taken from an examp le ofAn omia trigon alis (refiguredMC . p l . cxxv, fig . 1 ) enlarged, revised, and adapted to an outlineof An .

“

striata ; the large specimen of which he evidently used as

the basis of his communication . This sp ecies l

he had from Derbyshire and Cork (MC . ii, p .

The gen osyn typ es, therefore, of Sowerby ’

s Sp irifer are really theTerebratulce of Lamarck with triangular foramen , the An omitcefigured and named by Martin, in which Sowerby had found sp irals(M C. ii

,pp . 141 , These are An . striata and An . trigon aliswhich he had confounded with it— the Van Diemen’s Land specimens

may be ruled out . The authors who have chosen An . striata to bethe gen o lectOtyp e s eem to be qui te within their right . In that case,choice having been made , it stands good .

O n theDistributio n o fPro ductus ham e ro sus subla e vis)lan d the Z o n al Ran ge o f the

“Brachio p o d Be ds

”

o f the Midlan ds.

By Professor T . FRANKLIN SIBLY,D .Se . , F .G .S. Armstrong College,

Newcastle upon Tyne .

IN1908 the Productus humerosus beds 1n the Carboniferous Limestone .Oi Caldon Low

, N. Staffs, were tentatively assigned to theLower Dibun ophyllum zone , D1, of Vaugh'an ’s classification . Theslender evidence for this correlation was set out in my pap er onthe Midland Area .

More recently the researches Of Mr . L . M . Parsons In Leicestershire have established the Dibun ophyllum age of the well knownProductus humerosus beds of Breedon - on -the Hill an d Breedon‘Cloud . Mr . Parsons showed that the do lomites with Productushumerosus, in those localities contain Cyrtina sep tosa, a well - knownD1 shell that they are overlain conformably by dolomites with chertwhich y ield, at Breedon Cloud

,a rich D2_ 3 fauna of corals an d

brachiop ods ; and,further

,that they are underlain conformably ,

at Breedon - on - the - Hill, by beds with Mthostrotion irregulare an d

Cyathophyllum aff,rnurchison i . 2 The position of the Productus

hunterosusbeds of Leicestershire at the top of the subzone D1 was

thus firmly indicated, an d the above mentioned correlation of thebeds at Caldon Low incidentally received confirmation .

In the interval it had become known, through the researchesofDel ép in e and Vaughan, that Productus sublaevis de Koninck, a specie swhich includes Pr . humerosus

, Sowerby , occurs persistently an d

abundantly on a much lower horizon in Belgium and in the1 Quart. Journ . Geol . So c .

,vo l . lxiv, 1908, p . 44 .

2 Ibid . , vo l . lxxiii , 19 18 , pp . 94—100.

On the Di str ibuti on of Productu s humer osus’

. 2 1

Clitheroe district of Lancashire,namely , in the upper part of the

Can in ia zoneIt is, therefore , evident that Productus sublcevis occurs abundantlyon two widely different levels in the Avon ian ,

one in the Upp erCan in ia Zone, the other at the top of the Lower Dibun ophyllurnZone . “

Dr . Wheelton Hind , in questioning Mr . Parson s’s referenceof the humerosus beds of Leicestershire to D1, and at the same timeaffirming his own belief in a Can in ia age for the humerosus beds ofCaldon Low

,failed to take this view .

2

Strong confirmation of the Dibun op hyllum age of the CaldonLow beds is now supp lied by Mr . J . Wilfrid Jackson’s discoveryof Productus humerosus in limestones of “ Brachiop od Bed typ ein Dove Dale, only a few miles to the north - east of Caldon Low .

3

The Brachiopod Beds of North Staffordshire an d Derbyshirewere described by me as an . abnormal facies, and'

assigned to D9 ,with the qualify ing remark that they possibly encroach up on D3:1They have long been accepted as knoll - reef dep osits of D2" D3age , paralleled by the upper _

Or Cracoe knolls in the Clithero e i Cravenregion of Lancashire, an d by the massif of Visé , in Belgium . It is,

however, most interesting to find in Mr . Jackson’s account of theo ccurren ce of Productus humerosus in Dove Dale

,evidence which

definitely suggests that the Brachiop od Bed phase in the Midlands ran geso downwards into '

D, . The limestones bearing Pr

humerosus in Dove Dale are clearly of kno ll - reef type, both intheir faunal characteristics an d in their lithic structure ; and thetop of D1 is at once suggested as their ho rizon by a consideration ofthe humerosus beds of Leicestershire . It may be remarked thatif the humerosus beds of Dove Dale lie some 500 feet below the topo f the Carboniferous .

Limestone, as suggested in Mr . Jackson’saccount of them

,then their stratigraphical position corresponds

rather closely with that of the D l—D,boundary as roughly determinedin the Buxton - Longstone traverse of the Midland area .

5

In concluding this note I take the opp ortuni ty of expressmgthe interest with which I am following Mr . J . W. Jackson’s researchesin the western part of the Midland area,

a tract which was mostinadequately studied by .myse lf, an d the hope that he will succeed

1 “ In the Franco - Belgian area the early , smooth form o f Pr . sublcevis Occursin a p ersistent ban d between Tournaisian an d Viséan . In the South -WesternProvin ce this mutation is very rare it h as

,however

,been recorded from the

0 2 oolite o f Burrington. In the Clitheroe area , the early Pr . sublcevis enters at

the top of 0 1 an d forms a persistent ban d at the top of C2 (as in

(A . Vaughan, Quart. Journ. Geol. Soc. , vo l . lxxi , 19 15—17, p .

2 GEOL . MAG . , 19 18 , p . 480 . Dr. Hind ‘quoted the occurrence Of Cyrti n asep tosa in the humerosus beds o f Leicestershire as o n e in di cation of Gamma

age as against D1 ag e , n otwithstanding the fact that Cyrtin a sep tosa occursin D1 of Derby shire an d the South -Western Province, an d charactemze s

a p ersistent band in D1 o f the North -Western Province.3 GEOL . MAG. , Vo l . LVI, 19 19 , p . 335 an d pp . 507—9 .

4 Quart . Journ; Geol . So c. , vo l . lxiv , 1908, p p . 47—50 .

5 Ibid . , vo l . lxiv, 1908 , p . 39 , fig . 2 .

2 2 P ercy E . Raymon d— The Pyg i dium of the Tr i lobi te .

in throwing further light up on the p roblem Of the Brachiop odBeds Little or nothing is y et known regarding the transitionfrom these knoll - reef dep osits into the' standard limestonesof the district, while their rich fauna affords a great field for discriminating study .

The Py gidium o f the Trilo bite .

By PERCY E . RAYMOND , Ph .D .,Harvard Un iversity , Cambridge ,

Massachusetts, US A .

LTHOUGH the process of development of the pygidium in thetrilobite has been known since the time of Barrande , itssignificance does not app ear to have been app reciated , an d much ofthe modern sp eculation on the classification of trilobites is basedup on the erroneous idea that those sp ecies whose form is mostannelidan are most p rimitive . As a matter of fact, the study ofboth morphology and ontogeny shows that in this group the largepygidium is p rimitive and the small one sp ecialized .

The growing p oint in trilobites is , as in all other arthropods,immediately in front Of the anal segment . This was proved byBeecher from a study of the app endages of Triarthrus , an d is confirmed by facts more recently afforded by specimens of Neo len us and

Cryp to lithus having the app endages attached . New segments must ,therefore,be introduced during moults, an d each is pushed forwardthrough the pygidium by those which are added later . While these

segments are , as thus introduced, p otentially free , they do n ot

actually become so until they are pushed Off from the anterior end ofthe pygidium . The thorax, therefore, grows through the degenerationof the pygidium . Thi s p rocess can be seen in the ontogeny of al lspecies where an y considerable number of growth - stages are known,but can be studied in greater detail in Barran de ’s classic descriptions of Sao hirsuta and Dalman ites sosialis . In all cases it is foundthat the pygidium of the protasp is is p roportionally larger than atan y later stage in the life - history , an d this is equally true of anelongate Meson acid or Of a Phacop id such as Dalman ites . If theprop ortional length of the pygidium of Sao at various stages beexamined

,it will be found that in the very smallest p rotasp is it is

about 30 p er cent of the whole, at a length of 1 mm ., while there

are still no free segments, the animal is p ractically isopygous , an dfrom this stage to a length of 7 mm . the p rop ortional length steadilydrops to the 7 or 8 p er cent which remains in the adult . Al l

trilobites , whether the adult has a large or a small pygidium ,

show this same process, and Tro edsson has recently described a

particularly interesting case . The pygidium of Dalman -ites eucen trus

(Angelin), when 12 8 mm . long , has eight pairs of p leural ribs ,indicating the p ossession at that stage Of two more segments thanthe adult . 1 This case is of the more imp ortance on account of the

1 Lun ds Univ . Arsskr. ,n . f. avd. 2 , bd. 15, n r. 3, 19 18 , p p . 57—67, p l . i , fig . 23.

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24 P ercy E. Raymon d— The Pyg i dium of the Tr i lobi te .

the glabella is less furrowed than the axial lobe of thepygidium a condition unusual among trilobites . In thereversed position , the axial lobe of the anterior shield usually showsthree pairs of furrows, the normal number of glabellar furrows inmost trilobites .

The only valid obj ection which I can se e to reversing the usiualorientation is that in the new p osition the segments -woul d overlapin a direction Opp osite from that of all other Crustacea . Thatdifficulty appears to be a serious and fundamental on e .

THE PROTASPIS .

Professor Swinnerton has introduced a new point of vi ew, buto n e which might have been exp ected, by suggestin g that the p rotaspisis a sp ecialized larva, adapted to a p lanktonic mode Of life , and thatcharacteristics derived from its later development have no phy leticsignificance . ‘ This is, of course, the view which has lately beenheld by nearly all zoologists concerning the naup lius of recentCrustacea, and both views have their .Origin in the annelidtheory . Why ,

if trilobites were e volved directly from . benthonicannelids, did they not retain the Old planktonic trochophore, insteado f evolving a n ew typ e, which in no way resembled the supp osedancestor or its larvaSwinnerton says that the larvae of the Meson acidae are the mostprimitive known . That may be true, as they are certainly the mostancient, but he Continues to overlook the fact that the very youngeststage of the Meson acid larva has not y et been found . Beecher po intedthis out, and roughly figured a specimen y ounger than an y illustratedby . Ford or Walcott . 2 The ey es of this sp ecimen were verynearly marginal, and in the y oungest p rotaspis probably wereactually on the edge . Beecher had worked over the Ford co llectionOf larval Mesonacidw, and certainly did not ignore them in makinghis classification . As a p rotasp is, the larva of the Meson acidaedoes not differ fundamentally from that of other trilobites, but thedevelopment is different, because of the absence o f facial sutures .

Irresp ective Of the p resence or absence of ey es, the circular orbroadly oval form of the protaspis shows that bey ond question itwas a member of the plankton . But the evidence seems to indicatethat it was not there as a secondarily adap ted larva ,

but because itsancestors o ccupied that habitat . The broad lateral expansion s(pleural lobes) p resent in larva and adult alike gave to the trilobitesa shell which was easily kept afloat, and while not adapted to rap idswimming was a source of buoyancy .

“

It has been shown above thatthe large pygidium is p rimary ,

that is, those trilobites are most primitive which are best adapted to keep afloat, and those most sp ecializedwhich become adap ted, by assuming a worm- like form

,to crawling

1. GEOL . MAG . , Vo l . LVI, 19 19 , p .

.

109 .

2 Amer. Geo l . , vo l . xvi, 1895 , p . 175 , fig . 6 .

P ercy E . Raymond— The Pyg idium of the Tr i lobi te . 25

life on the bottom . As had already been suggested , first, I believe,by Spencer, the pygidium was p robably used as a caudal fin, p erhap smore in the manner of the up and down motion of the tail of Sagittathan in the spasmodic flaps of a lobster . That the longitudinalmuscles had considerable power

,however

,is shown by the greatwidening of the axial lobes of many trilobites with large pygidia .

The app endages also show that most trilobites were swimmers as

well as crawlers, though none so far investigated show an y particularadap tation for the purp ose of swimming except Triarthrus, whosepygidium i s small .The trilobite was not a powerful swimmer

,but on the other hand

it was n ot'

in an y case entirely spe cialized for bottom life . Theneed for a floating type of larva was not great, since floatingcharacteristics dominate over crawling characteristics in the adults ,and thus such evidence as exists points to a pelagic rather thana benthonic ancestor for the group .

BAOKWARD MIGRATION OF THE EYEs .

Beecher made no attempt to_explain this mi gration, which formed

so fundamental a feature in his classification . Two factors seemto be involved . In many cases there was little

.actual change Of

p osition , but the ey es of the adult are relatively further back becausethe brim In front of them has grown outward . In others there isactual backward translation, an d this seems to be due to the Increasein size Of the anterior digestive portion of the alimentary canal,which bulges out the anterior end of the glabella, pushes back themouth

,and doubtless, the ey es, their nerves and ganglia . This

enlargement of the stomach is p robably correlated with thechange from a planktonic mode of life, where the food was chieflythe concentrated micro - organisms, to the benthonic habitat, wherean omnivo rous or even vegetable diet may have been adopted .

This change, though one Of food , seems to have been so fundamentalthat its results became impressed upon the race, and thus the positionof the ey es came to be of classificatory importance .I think it will be evident from what has been said above thattrilobites as unlike as Cryp to lithus, Harp es, and Dion ide could -be

descended from an Agn ostus—like ancestor, an d that those who wish

to place the Agn ostidae an d Trinucleidae among the degenerateanimals must bring forward some p roof for their assertions whichis not based up on the theory that, trilobites descended from benthonicannelids . For further details and a full statement of the ideasexp ressed above, the reader is referred to a memoir by the authorthat is shortly to be published by the Connecticut Academy of Artsand Sciences .

.26 A . E. Tru eman— The Ammon i te Sip hun cle .

The Amm o n ite Siphun cle .

By A . E. TRUEMAN, D .Sc . , University College, Cardiff

IT is well known that the chambers of Cephalopod shells are con

n ected by an organ called the siphuncle, which passes throughthe sep ta by the septal necks . Many investigators who have studiedthese shells have made careful observations on the siphuncle, hop ingthereby to throw light on its functions . Such workers as Branco ,B lake

,Zittel

, an d Owen , among many others, have written on thisp roblem,

while more recently an elaborate study of the structurean d constitution of the siphuncle has been made by Grandj ean , 1 whog ives a detailed account of the organs associated with it. Amongthe many p oints established by Grandjean ’

s work,not the least

interesting is the fact that the siphuncul ar tube Of '

Ammonite s and

Belemnites is composed of calcium phosphate , and not, as hadp revi ously been stated , of calcium carbonate . 2 But in sp ite ofGran djean

’

s careful exami nation of the less Obvious characters ofthe siphuncle

,it app ears that certain facts

,much more easily

Observed, have hitherto been overlooked .

TERMS .

The word siphuncle in Ammonite literature is used somewhatloosely ,

just as the word siphon is used in the same connexionby French authors . As Grandj ean pointed out

,however

,the

siphon (or siphuncle) p rop er is a membranous organ ; the tubeof calcium phosphate found in fossils, an d commonly referred toas the siphuncle, i s simp ly the solid sheath , which it will be moreconvenient for the present purpose to call the siphuncular tubeo r envelop e .

CONTINUITY OF THE SIPHUNOULAR TUBE .

When examining some large sections of Ammonites the writernoticed that the siphuncular tube was n ot . continuous throughall the chambers to the body - chamber

,even when the sections

were p erfectly median . It was at first thought that this was an

unusual character,but when other sections were examined similar

facts were noticed, and a more systematic inquiry was therefore

undertaken . Ammonites were examined by kind p ermission in theCollege and Museum collections at Bristol , Cardiff, and Nottingham ,

an d while only a small p rop ortion of the ammonites seen weresufficiently comp lete or accurately cut to give the desired information

,in every sp ecimen which showed enough detail the same

rule was found to hold good .

A section of Asteroceras obtusuin of diameter 70mm . in the1 F. Gran djean Le Siphon de s Ammonites et des Belemni tes Bull. Soc .

Geol . , Fran ce, se r . Iv, vo l . x , 19 10 , p . 496 .

2 This further poin t o f resemblan ce between Ammonites an d Belemn ites 1sin terestin g In view Of Dr. W. D . Lan g’

s rece n t suggestion concern in g theirclassification (Proc. Geol . Assoc.

, vo l . xxx, p .

A . E . Tru eman — The Ammon i te Sip hun cle . 27

Natural History Museum,Nottingham ,

shown diagrammatically inFig . 1

,will serve to illustrate the character in question . That

the section is cut accurately along the median plane is shown bythe p osition Of the keel an d the size of the sep tal necks for thepassage of the - siphuncle . The siphuncular tube can be clearly seenalon g the greater part of the sp iral, but after a diameter o f .38 mm .

(S, Fig . 1 ) no trace of the siphuncular tube can be made out“ in thesucceeding ten chambers . The wide septal necks in the sectionat that p oint show that its non - app earance is not due to asymmetry .

‘

Apparently the only conclusion that can' be drawn , therefore, is

that the siphun cle, which was, of course, continuous throughoutthe sp iral, had an envelope which did n ot extend through the tenchambers precedin g the living chamber .

FIG. 1 .

— Diagram of a section o f A steroceras obtusum (Sow. ) showingthe sip hun cular en velop e (S) .

Similar.

facts were also Observed in the following Ammonites1 . A large un iden tified specimen from the Inferior Oolite in University

(College , Cardi ff . Diameter 330 mm. Part Of livin g chamber p resen t. Six

chambers without a siphun cular en velop e. These six chambers an d the livingchamber are filled with oolite , the earlier chambers with calcite .

2 . Parkin son ia sp . University College, Nottingham . A sp ecimen,diameter 240 mm sep tate throughout (that is, w1th n o p art Of the bodychamber re tained ) , has n o siphun cular tube in the last three - quarters o f a

whorl . That is , for at least fifte en chambers there was n o siphuncular en velop e.3. Deroceras sp . Natural History Museum , Nottin gham . DIame te r

85 mm . Sep tate throughout . NO siphun cular tube after diameter 44 mm . ,

that is, at least fifteen chambers without.

4 . Harp oceras exaratum. Un iversity College, Cardi ff . Diameter 76 mm .

1 Further, asymmetry is o f extremely rare occurren ce in such keeledammonites . Se e Swinn erton Trueman , Quart. Journ . Geol . So c. , vo l . lxxiii ,19 18, p . 54 .

28 A . E . Truein an — The A inmon i te Sip hun cl e .

Portion o f li vin g chamber p resent. NO siphuncular envelop e after 43mm. ,

that is twelve chambers without.

5 . Oxyn oticeras oxyn otum. Welsh National Museum . Has n o siphunculartube for twenty - five chambers, the whole Of the last whorl.6 .

? Li oceras sp . Bristol Un iversity . Diameter about 150 mm. Bodychamber p resent. NO siphun cular tube in last n in e chambers . The bodychamber an d the p receding ni n e chambers have oolite filling , the earli erchambers have calcite.It frequently happ ens that while the chambers of an Ammonite

are filled with calcite or other crystals, the body—chamber is filledwith material such as clay or oolite, whi ch was able to get in whenthe animal decay ed . But in several of the Amm onites referred toabove

,not only the body - chamber

,but also the chambers without

a siphuncular tube,were filled wi th such material , probablyindicating that when the Ammonite died the siphuncle decay ed ,

allowing detrita'l material to enter those chambers where there.was no siphuncular tube . Using this typ e of evidence it would bep ossible to extend the above list very considerably .

OTHER INDICATIONS OF A DISCONTINUOUS SIPHUNCULAR TUBE .

Whi le the most Obvious way of investigating the continui ty ofthe siphuncular tube is by means of medi an sectio n sfy et usefulinformation concerning some Ammonites has been Obtained fromcasts and

'

, impression s . These cases may be considered in threegroup s1 . In some casts of Ammon ites, especially those whi ch havebeen rubbed or polished

,the siphuncular tube may be seen alongthe extern al margin . In such casts it was found that the siphuncular

tube did not continue unbroken to the body - chamber .For instance, a polished cast of an unidentifiable Ammonite in

the teaching collection at University College, Cardiff, has a continuous siphuncular tube up to a ' diameter of 175 mm . Followingthis are three chambers

,the remainder of the shell not being present .

The siphuncular envelope in these chambers is discontinuous (se eFig . In the last two chambers short p ortion s of the tube (S 2,8 3) are attached to the front sep tal neck only in the third chamberthe p ortion of the tube is free (S 1 ) and on the side of the cast . It

app ears , therefore, that the tube was discontinuous in thesechambers (and in an y others in front that may originally have beenp resent), and that the secretion of the solid tube commenced betweenthe septa , each portion becoming attached to the septal neck infront . With the death of . the animal the siphuncle decayed , an d

these p ortions of the tube were unsupported , an d the shell havingfallen on its side they either hung loosely from their attached ends(S 2, S 3) or slipp ed along the inside of the shell (SA similar condition is shown by an examp le of Hop lites deshayesi

(Leym . ) in the Welsh National Museum . In this sp ecimen part ofthe living chamber is p resent at a diameter of 70 mm . The siphuncular tube appears on the outside of the cast as a contin uous black

A . E . Tru eman — The Ammon i te Sip hu n cle . 29

band, passing through all but the last two chambers .

In the lastchamber no trace of an y siphuncular tube can be seen

,but in the

preceding one a short p ortion Of the 'tube has slipped along the sideexactly as in Fig . 2 (SThese two cases

(

suggest that in some of the sections describedthe apparent absence

'

Oi an y siphuncular tube may be similarlydue to the falling away of the inter - septal p ortions Of the tube .Nevertheless

,there is no doubt that the tube was not present in

the last few chambers of all the specimens mentioned .

FIG . 2g— Diagram showin g the discontinuous siphim cular tube in a

Hildo ceratidAmmon ite. S represents p art of the normal siphuncular tube,with loose portions at SI, 82, an d 83.

2 . Casts of Aetomoceras scip ion ianum and allied formsfound in the phosphatic beds at Radstock, Somerset, afford furtherconfirmation . The siphuncular tube is generally broken away ,leaving a g roove along the external margin, but the keel is stillpresent on the cast of the body - chamber an d on several chamberspreceding it . This suggests that there was no siphuncular tubethose chambers, otherwise it would also have been broken away .

3. Many sp ecimens Of Psi loceras cf . p lan orbe found inthe Lias at Lavernock , near Cardiff, have been flattened In preservation

,and in many cases the shell was evidently so thin

.

that it isonly n ow rep resented by the outer horny lay er . This is soOn wornor even blown away , an d then the imp ression Often shows thesiphuncular tube as a white band running round the spiral . 1 As

this does not extend into the outer two whorls it is extremel yp robable that here again there was '

n o siphuncular tube in the lastfew chambers .

THE SIPHUNCULAR TUBE IN YOUNG AMMONITEs .

There are two possible exp lanations of this absence or in comp leten ess Of the s1phun cular envelop e in the last few chambers

1 Mr. F. F. Miskin , kin dly e xamin ed a number Of theseAmmon itesa n d p roved that thi s white material was calcium phosphate, an d thereforerep resents the siphuncular tube.

30 A . E . Tru ern an — The Ammon i te Sip hun cle .

of Ammonites . It may have been an Old- age or adult character, .

indicating feebleness of“ powers Of phosphate secretion , or it mayhave been a normal feature of growth, the envelop e being formedby a siphuncle but always leaving several chambers in which it wasincomp lete .To test the truth of t his latter suggestion sections were cut

through a number of young" Ammonites, those selected being youngindividuals with at least a portion of the body - chamber p reserved ,an d n ot simply the inner whorls of adults . In each exampleinvestigated it was found that in the chambers preceding the livingchamber there was no siphuncular envelop e .The following sp ecimens were cutHi ldoceras cf . bifron ’

s fromGrantham . Diameter 24 mm .

Scarcely an y sign of a siphuncular envelope in the - last whorl .Dactylioceras sp . from Grantham . Diameter 35 mm . NO

siphuncular tube in last two chambers .

Amblycoceras sp . from Leckhampton . Diameter 42 mm . NO

siphuncular tube in last three chambers .

It therefore app ears that in many , if not all , ammonites, y oungand old, the siphuncle is without an envelop e in the chambersp receding the body - chamber . The number of chambers in whichthere is no envelop e apparently increases with the age o f the

individual,but probably dep ends on other conditions also .

PREVIOUS OBSERVATIONS ON THE EXTENT OF THE

SIPHUNCULAR TUBE .

SO far as the writer is aware , this incompleteness of the siphuncularenvelop e has not p reviously been recorded, although, curiouslyenough , Zittel has described an exactly Opposite instance . 1 In

some casts of A . e limatus from Williamswitz the siphuncular tubeis not preserved

,an d the groove which presumably marks its

position app ears to p ersist a sho rt way into the body - chamber .Beyond this Zittel gives no information, an d apparently did notrefer to it further in his later works . While this observationmayindicate that in some species or individuals the secretion o f an

envelop e p roceeded more quickly than in those described above, itis doubtful whether the secretion actually o ccurred within thebody—chambers, an d it must be p ointed out that Zittel was rely ingfor his evidence not on the actual siphuncular envelope but on theextent of a groove which may have contained it .Grandj ean suggested that Zitte l ’s Observation affords a p ossibleexp lanation Of the formation of the siphonal membranes, the ‘

association Of which with the covered siphuncle he was unable tounderstand ? It may be briefly noted that the facts recordedabove make it p ossible to give an equally Simple explanation .

In Oppel, Palaeon t. Mitt. Mus . d . k . bayer. Staates, Bd . iI, 1868, pp . 79—80.

I have to thank Mr. F. T . Ingham, B.Sc. , for supp lying p articulars Of thisp ap er.

2 Op . cit. , p

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32 R . F. Ran d— A n gra P equ en a

that the siphuncle in Nauti lus can hardly serve for such a purpo seas Mr . Spath suggests . The animal would fit sufficiently tightlyin the shell to p revent its falling out, even when the shell muscleswere detached .

1 For instance,some force is needed to pull a dead

gastropod, such as a snail, from its shell even after the muscleattachment is broken .

Without discussing at an y greater length the functions Of theAmmonite siphuncle . it may be mentioned that in the writer’sOpinion the suggestions of Foord 2 and Dr . Henry Woodward3 are

much more reasonable than those mentioned above . These writerssuggest that the siphuncle was of more importance in the y ounganimal

,perhaps then serving for attachment, but that later onthis function was performed by the shell muscles . It is not unlikely

also that the siphuncle was of much greater importance in the earlystages Of Cephalopod evolution than it is in Mesozoic an d recentforms . This will be more ' clearly recognized when an attempt ismade to assign “

a function to the siphuncle of a Belemnite, where it isalmost certainly nothing more than the remains of an organ whichwas probably of value in the early hi story Of the race, and perhap sin the early development of the individual . The tendency for thesecretion of the siphuncular envelop e in Ammonites to lag behi ndshell - growth suggests that the value of the siphuncle may at leasthave been declining .

A n gra Peque n a (Lude ritzbucht) an d Subae rial

De n udatio n ;

By R. F. RAND , M.D.

N recent y ears the name of Angra Pequena,conferred by

BartholomewDiaz,has been somewhat obscured by the designation

Luderitzbucht,the name given to this port during the German

occupation . The latter name still holds, although a compromise,whereby the geographical area Should retain the Old name and thetown be known as Luderitz

,seems desirable .

Angra Pequena (Luderitzbucht) and Walfisch Bay are the on lytwo useful harbours of the South -West African Protectorate . Apartfrom its harbour

,the town of Liideritzbucht and the surrounding

district have received much attention owing to the considerablefinds of diamonds which have been made along the coast, both tothe north and to the south of the p in t.

TO the geologist the Angra Pequena area is of interest as affording1 This would be equally true o f Ammonites, in which Mr. Spath suggests

that the comp lex lobes an d saddles served as an attachmen t. Se e alsoDr. W. D.

Lang , The Evolution o f Ammonites Proc. Geol. Assoc. , vo l . xxx, 19 19 ,p . 63.

9 H. O. Foord, Catalogue of Fossi l Cep halop ods in Brit. Mus , vol . 1, 1888,

pp . 10—1 1 .

3 H. Woodward, P op . Sci . Review,vol . x i, 1872, p .

‘

1 13.

an d Subaer ia l De'

n udati on . 33

an admirable instance of aeolian denudation . It is a desert area,a

region of rock an d sand . The average annual rainfall is 0 78 in .

There are no running streams . Water for drinking purposes mustbe imp orted or distilled from sea—water .The rocks are of the ancient metamorphic comp lex, so wide

sp read over the Protectorate . A confused medley of granite, ap lite ,gneiss, and schists . There is much commingling of typ es as a resultof inj ection

, p ressure, an d earth - movement .Overlooking the town of Luderitzbucht there is a rocky eminence,known locally as the Diaman tberg , which within an area of a square

mile or SO Sho'ws many typ es The p revailing one is, p erhap s , a

biotite - schist, which In many p laces has been invaded to a vary ingdegree by granite or by ap lite . The difference in colour betweenthe schistose and the granitic elements shows up the degree ofadmixture very clearly . In some places masses of schist are to beseen uninvaded by granite, in others masses of granite or of ap liteo ccur without trace of schist . Here an d there are large segregationsof quartz . Veins and ey es of felspar are common . The ro cks are

e xp osed up on every side, for there is no vegetation that countsto mask or protect them .

Although the rainfall IS SO small the country is carved into hilland valley , an d ravines course down the steep er slop es . The floorsOf

' the valleys are occup ied bymixed sand and grit, a fluent medium,

which is disp osed much as. water would be in a non—desert area ,

broaden in g

'

as the valley opens out, narrowing as it closes in likea sand river - bed, which frequently p rovides the most convenienthighway for man and beast . ‘Heat by day and cold by night havetheir due effect no . doubt, ‘but it is the wind which is mainlyresp onsible for the large quantities of rock - waste and debris whichlitter the surface upon all sides, an d for the honeycombing the

rocks have so frequently undergone .The great destructive wind of this area blows from theIt is a

‘

season al wind blowing from October until April . Years agoAndersson noted its effects up on the habits of certain birds . Perhapso nly a light breeze in the morning , it rises to a gale in the afternoon ,dy ing down again after nightfall . From time to time there arecalm days . It is a wind laden with salt and with moisture whereit fi rst strikes the land thereafter it lays the desert under tribute ,an d armed with gr it and sand scours every thing in its path .

N0 rock entirely withstands the attack . Effects vary . It is rathercurious to se e how in large boulders, say , of granite,

'

- apparentlyof even texture throughout, one p ortion Of the mass may be merelydull p olished and lightly scooped out, whilst another portion isdeep ly bitten in to .The biotite schist shows the ravages consp icuously . The rockis pitted

,riddled

,

“

and holed , with worm—eaten ”

, honeycombedeffect . It rots away . Near to the sea,no doubt

,the salt m the ai r

,

owing to its chemical reaction with the ferrugirious element of theschist, adds to the destructive effect .

VOL . LVII .

— No . I .

34 R . F. Ran d— Ang ra P equ en a

The holes bored into the rock are usually more or less circularIn outline at the inlet, an d burrow into the rock to vary ing dep ths .

The cavities worn are chambered out and frequently coalesce,giving rise to cells and caves which are sometimes“ large enough toShelter man .

Should granite and schist have been rolled out into even,alternate

laminae , and the constituent minerals disp osed in order, the holesmay be regular in Size and lie in a straight line . If equidistant ,as they sometimes are , they may look as though drilled by humanhand . Sometimes the outlines are quadrangular, and the rows mayeven suggest the p igeonholes in an Office desk . There may be Simp lysmoothing and dull - p olishing of such a rock, an d should the lay ers.

crop out vertically they Show ridge and furrow, the harder granitebeing in relief .Where there has been intimate admixture of felspar and schist

the more resistant felspar stands out in studs . The veins of felsparalso p roj ect, but with their sides unsupp orted the felspar is at themercy of its main cleavages and falls in fragments . High up up on.

cliff- faces one may se e holes which resemble those made by martinsin some hosp itable sandbank .

The g ranite varies very much in its resistance . Sometimes it isdeep ly holed and cavernous sometimes it shells away in concentricflakes ; sometimes it shows good resistance an d is merely dullp olished .

The segregations of quartz are, as one woul d supp ose , very

resistant . Such masses have their surfaces more or less polishedand - lightly scoop ed out into shallow dep ressions of vary ing Size .All salient angles are rounded Off . There is a general smoothingover . Pitting , in quartz, when it occurs, is usually small and dueto the breaking down,

Of small less - resistant inclusions . Yet thefoot of a quartz slop e is littered with angul ar fragments, owing,apparently , to the minute fissures and j oints which traverse themass .

Most of the holes one sees,whatever the nature or texture Of the

rock,are driven more or less horizontally inwards, after the fashion

of adits, but holes are sunk downwards also . The chemical actionof the wind - borne salt and moisture

,an d the grind of the air-

.drivensand - an d grit, sap at all vulnerable surfaces . As the holes deep enthey come more and more under the swirling effect and scour of therock fragments, sand, and grit which they come to harbour . Theymay be regarded as mo lian pot - holes ”

The lofty sides of the ravines and gullies have their rocks deep lyhoney combed and wind bitten . Air currents frequently co'urseup or down them with violence . The holes may face up or down the .

ravine . Perhap s there are more which face downwards . Air

currents in broken country are so cap ricious and so easily deflectedthat there can be little rule .On e has to See the large quantities Of waste littering the surface

an d Subaer ia l Den udatio n . 35

to realize the rap id rate at which the rock is being destroy ed , andone has to exp erience the force of the wind adequately to estimateits driving p ower from its set quarter .N0 on e doubts that the strong S.S.W. wind has been the agent

by which a n atural concentration of the diamonds in the valleysof the Li'ideritzbucht districthas been brought about, ‘

a Concentrationwhich has made their exploitation economically p ossible . As thediamonds have not been shown to extend very far inland it has beenthought by some that marine agency has had something to do withtheir occurrence . It has been p ointed out that the coast is undergoing slow upheaval, and that diamonds have been foun d in thematerial of the raised beaches which terrace the hills in certaino f the valleys of the littoral . But as to this the re seems to be n oreason why the enrichment should not . have taken place from a

landward area,

‘

and not necessarily from seawards .

It is quite likely that the S.S.W. wind may be entirely responsiblefor the denudation Of the parent diamond - bearing ro ck as Well asfor the concentration of the diamonds after being set free . Theoccurrence of the diamonds near to the sea is probably due to thefact of the denuding agent being a coastal wind . This coastal windoccupies a stratum which does n o t reach to an y considerable height.into the atmosphere . AS on e proceeds inland the country r1ses

fairly rapidly . In the experience of the writer it may be blowinga gale at Luderitzbucht, while at Haalenberg , 33 miles inland byrail, and considerably less as the crow flies

,the air may be nearly

still . Haalen berg is 1 ,816 feet above sea - level . An arbo rescentaloe, A loe dichotoma, common in the interior, comes down to aboutthis neighbourhood . It does

’

not reach the coast, it could not withstand the wind, a lthough there are swi tch forms of vegetationwhich can bow before the wind,an d lowly p lants, mostly of fleshyhabit

,which can win their way as far down as the sea . It would

seem that we have in noting the habitat of such arbo rescent forms

as A loe dichotoma a gui de to the limitations Of the coastal windin both vertical an d lateral planes, and consequently to the areathe denudation of which has furnished the diamonds .

The hi lls ly ing inland between Liideritzbucht an d Kolmanskopare of metamorphic rock, an d in general resemble the Diaman tberg .

They are not hi gh, and one hill is very much like another . Verycuriously the broad effect Of the landscap e in this region is suggestiveof a terrain which has been swept by an ice - sheet . There are thegenerally rounded outlines, the" hummocky effects . The r esemblancemust be illusory ,

for subaerial denudation is going on SO rap idlythat one judges the outlines to have been comparatively recentlyimposed . The directional trend of the sand blast may be responsiblefor the likeness .

REVIEWS.

SUMMARY OF PROGRESS OF THE GEOLOGICAL SURVEY OF GREATBRITAIN FOR 19 18 . pp . 70 , with 3 text - figures . 1919 . Price23. 6d . net .HIS publication forms remarkably interesting reading , for

several reasons . In the first p lace we have at an y rate a

partial lifting -Of the veil of secrecy that has shrouded some of themore important .work of the Survey during the War

,an d it is

p ossible to make a shrewd guess at the nature of some of themore recondite investigations undertaken by its Officers for theNavy , the Army , and the Air Forces . Besides references to the moreobvious but exceedingly necessary advisory work on water supplyand road metal at home an d abroad an d the geology of mining an d

tunnelling on the Western Front, we are treated to the briefestcataloguing of such tantalizing items as Rep orts on Selection ofQuartz - crystals for Anti - Submarine Division of the Admiralty ,

Report on use of Hex ahedric Crystals of Iron - pyrites by the

Germans Rep ort on a Prize Cargo ”

,an d others of a Similarly

mysterious nature .As is natural the activities of the small staff that remained were

almost entirely diverted to work Of an economic nature , or closelyconnected with the military and Commercial necessities of thecountry . Under this category come rep orts on the Oil—Shales Oi

Scotland, p ossible potash—bearing rocks from North Wales

,copper,

arsenic , salt, and cannel coal , with a rather full descrip tion of theoccurrences of the latter in Scotland . There is also an interestingaccount Of the lead and zinc mines in Scotland, including thoseOf Leadhill s an d Wanlockhead

, ‘

Newton Stewart, Tyndrum ,and

Strontian . A dep osit of bauxitic fireclay in Ay rshire has beenfound to po sse ess high value as a refractory .

In the way of pure geology the mapp ing of parts of Banffshireand Aberdeenshire has been revised and a good summary of thiswork Is given . Part of this, by Mr . H. H. Read

,.has already app earedin the GEOLOGICAL MAGAZINE under the attractive title of The

Two Magmas Of Strathbog ieSeven valuable app endices are added to the report

,all dealing“

with boreholes in different parts of the country ,namely ,

Kent,Lincolnshire

,Gloucestershire, Yorkshire, Holywell (Flint) , and

a p lace calledGosmore, which from a previous publication app earsto be near Hitchin,although this Is not here stated .

It IS highlySatisfactory to find that the Issue of the extraordinarilyvaluable series of Special rep orts on the m ineral resources Of GreatBritain is still actively p roceeding , three further volumes on iron - oreshaving just been issued, an d that it is intended to keep the seriesup to date by the frequent issue o f new editions . These publicationshave evidently filled a '

gap in the literature of economic geology in

Revi ewsfi Mi n era l Resources of Gr eat Br i ta in . 37

this country . The forthcoming? volumes will 'be awaited with much

interest,an d we may

' be allowed to hope that a volume or volumeson lead an d zinc are now on the way .

R . H. R .

SPECIAL REPORTS ON .THE MINERAL RESOURCES OF GREATBRITAIN

,VOL . VIII . IRON ORES ; HZEMATITES OF WEST

CUMBERLAND ,LANCASHIRE,

AND THE LAKE DISTRICT . ByBERNARD SMITH

,M.A . Mem . Geol . Surv . pp . 182

,with four

p lates and 29 text - figures . Price 98 . net .LL geologists who are in an y way interested in economi cquestions in general and m iron ores in particular will rej oice

at having at length an authoritative an d comp lete account o f thehaematite dep osits of north western England . This Is a subj ect Ofvery great geological an d technical imp ortan ce, as - to which reliableinformation has been singularly lacking , especially as regardslater developments . Mr , J . D . Kendall ’s work on the subj ectwas published over twen ty y ears ago , an d since then \ very littleseems to have app eared in connexion with the geological asp ectsof this great industry .

The Geological Survey is to be congratulated on having foundin Mr . BernardSmith an author who is capable of dealing effectivelywith all sides Of a large an d comp licated subj ect He gives an

interesting sketch of the early history Of the iron—mines,beginningwith the imp etus given' to commercial enterp rise by the foundation

of the great abbeys in the twelfth century an d gradually leadi ng upto the industrial revolution of 100 y ears ago , when blast furnacesusing coal and coke rep laced the primi tive bloomeries of the MiddleAges, an d eventually led tO the establishment of such giganticenterp rises as the Barrow Haematite Steel Company ,

Limited ,and the Hodbarrow Mine

,with its output Of 400,000 tons of ore

p er annum .

It is,of course, well known that the great importance of thishaematite ore lies in its remarkably small p roportion of phosphorus,which causes it to be eminently adap ted to the manufacture of

steel by the acid Bessemer p rocess, an d so long as the supply laststhe demand for this high—grade ore will inevitably continue .Fortunately there is every reason to believe that great res’ ervesstill remain untouched under the Duddon Sands an d elsewhere .By the very nature Of the case, such irregularly Shaped and Sporadicmasses as these must be di fficult to locate

,the only means availablebeing actual boring or Sinking ; p urely geological reasoning Is not

of much avail,though a detailed study of the stratigraphy such as

is here given is of much p ractical value in pointin g out likely localitiesfor such exp eriments .

Geologists will read with much interest Mr . Bernard Smi th’slucid exp osition of the facts an d arguments which have led him to

38 Reviews - Mi n era l Resources of Gr eat Br i ta i n .

the conclusion that the solutions giving rise to the metasomaticrep lacement of the Carboniferous Limestone travelled in the maindownwards from the overly ing _New Red rocks ; the first stageapp ears to have been the rep lacement of the tests of calcareousmicro - organisms by comp ounds of iron, this change afterwardssp reading to the fin e -

grained matrix and being accompanied orfol lowed by a certain amount Of silicification . The close connexionexisting between ore - bodies and fault—fissures app ears to be conclusive evidence Of the truth of. this exp lanation . Even the lode - likemasses of haematite in the Skiddaw Slates an d other ancient rocksseem to have been formed by descending solutions . The sopsof Furness

,which are obviously ancient p ot—holes, were first filled

by calcareous breccia an d afterwards metasomatized by iron"solutions

,and there is no real supp ort for the view that an y orebodies were dep osited in cavernous op en spaces in the limestone .The p ossible further underground extensions Of

“ the ore- fie ld an d

the amount of p robable reserves are fully discussed, an d 120 pagesare occupied by detailed descrip tions of the mines, illustrated byexcellent diagrams Of the forms of the ore - bodies an d theirrelations to vary ing rock—structures . It is estimated that the oreproved to exist amounts to about forty - five million tons, whilep robable reserves unp roved , may be ninety million tons, most ofthis being in Cumberland . The Lan cashIre field seems to berap idly app roaching exhaustion, only five million tons of ore beingactually known to exist .

This memoir is an admi rable examp le of the judicious combinationof scientific deduction an d p ractical knowledge that is so highlydesirable in the literature of economic geology .

SPECIAL REPORTS ON THE MINERAL RESOURCES OE GREATBRITAIN . Vol . IX,

IRON ORES (cont ) : SUNDRY UNBEDDEDORES OF DURHAM

,EAST CUMBERLAND ,

NORTH WALES, DERBYSHIRE

, THE ISLE OF MAN,BRISTOL DISTRICT ,

AND SOMERSET,DEVON

,AND CORNWALL . By T . C. CANTRILL,

R . L .

“

SHERLOCK,andH. DEWEY . Mem . Geol . Surv . pp . 87, with 7 figs . 1919 .

Price 3s . 6d. net .IN this volume we have a useful collected account of some relativelyunimp ortant sources of unbedded ores , partly in the form Of

rep lacement dep osits and partly as true mineral veins . Some Ofthe occurrences

,as those of the Carboniferous Limestone of North

Wales, Derbyshi re, North Somerset, and Devon , are similar in formand origin to the great haematite dep osits of North -Western England .

In the Isle of Man an d in the Coal—measures of Bristol haematiteoccurs in veins

, p erhap s due to alteration of calcite and dolomite byferruginous waters from the Trias . The spathic vein - ore Of WestSomerset

,.Devon

, an d Cornwall consists in dep th of chalybite, converted near the Surface to limon ite . I

In some p laces spathic ore is

https://www.forgottenbooks.com/join

40 Revi ews—Recen tGeop hy si ca l Rep r i n ts .

Re ce n t G e o p hy sical Re p rin ts.

1 . AN APPARATUS FOR GROWING CRYSTALS UNDER CONTROLLEDCONDITIONS . J . C. HOSTETTER . Journ . Wash . Acad . .Sci

vol . ix,1919 , p . 85 .

2 . THE HYDRATED FERRIC OXIDES . E . POSNJAK an d H. E .

MERWIN . Am . Journ . Sci . , vol . xlvii, 1919 , p . 31 1 .

AS is well known the Geophysical Laboratory of the CarnegieInstitute put aside its usual scie ntific pursuits to help win the

War, and on this account only two of the latest issue of reprints

from the Laboratory are sufficiently geological to call for noticein these pages .

1 . The apparatus for growing crystals described by Hostetterhas its origin in a German patent of Kriigen Finke . Its p rincipleis the circulation of solution from a saturator to a crystallizer an dback again . The temp erature difference varied with the salt usedand was generally kep t well under 05 °

C. The descrip tion is clear ,an d is illustrated by an admirable diagram .

2 . The hydrated ferric oxides, though a difficult subj ect,have

attracted considerable attention in the past. Many Of the individualresults attained by Po snjak Merwin are of the nature of confirmation rather than of original discovery ,

but this does not detractfrom their imp ortance . Our knowledge in its toute en semble was

hop elessly confused, and the p resent contribution is most welcome .Its main features may be summarized as followsFerric hydrates, both natural and artificial

,fall into two great

classes : Class I,orange to orange - y ellow an d class II, red to

reddish- brown . Class I has the empirical formulawith variable adsorbed and capillary water . Class II is of a differentconstitution .

Only the natural products have been met with as definite crystals .

These are of three kinds : Class I, Goethite and Lep idocrocite ;Class II, Turgite .

“Limonite falls to Class 1 . Much of What is commonly calledlimonite is Shown to be fibrous goethite, but other samp les are

indecipherably amorphous and for these the name limoniteis retained . Limonite in this “restricted sense may or may not begoethite . Its density an d refractive index, when corrected for theeffect of adsorbed and capillary water, point in the direction of thegoethite correlation, but as y et the evidence is not con sIdered

conclusive . Might not the absorp tion Sp ectrum of the streak helpto fill in this gap in our knowledge ClTurgite is interp reted as a solid solution of haematIte and

goethite, but in this direction the authors have not develop edtheir case very clearly . They base up on the density Of the threeminerals, and then remark all other evidence at hand is in favourof this assumption But in relation to the dehydration behaviourOf turgite, we had previously been told the shape of the curve

Revi ews— The Chan n e l I sla n ds . 4 1

p lainly signifies that the w ater in turgite is held in a different wayfrom that in the other hydrated oxides an d later

,no sudden

decomp osition takes p lace anywhere, an d it would seem that turgiteunlike the other hydrated ferric oxides, is not a definitely . hydratedcomp ound .

”

How are these s tatements to be reconciled with theview that some turgites contain about 50 per cent of goethite 1

.Of many other p oints of interest the following may be chosen 1(a) The orange to orange - y ellow hydrates (Class I) are foun d '

to

begin to decomp ose at an app reciable rate at about 200° C.,while

at about 300° C . their decomp osition becomes labile(b) For the same class, dehydration is irreversible where combinedwater is concerned

,and app roximately reversible where uncombinedwater is concerned .

(0) For turgite (Class II) dehydration is irreversible, but n o

temp eratures comparable with those referred to in (a) have beendetected .

In conclusi on one may perhaps venture on a comp laint . Muchmight have been gained by clearer exposition . It will suffice tomention a coup le of instances Of unnecessary obscurity in regardto figure 2 with its fourteen independent graphs . Each grap h isnumbered

, an d the reader is referred to two tables elsewhere in thepap er to find, by help Of these numbers, under what names thefourteen Sp ecimens ex perimented with were received from variousmuseums . It is a matter of further research to realize howfarthi s naming has been accep ted by the authors . It would have beena great help to have had the author’s naming indicated by initialsin the corner of each graph, as, for instance, Li . for limonite . Thenagain, figure 2 is described as giving temp erature— time dehydration curves It app ears that each graph in the figure co - ordinatessuccessive temperatures of a hydrate charge with the differencesof these temperatures and those of a Control body , where bothcharge and control have been heated in a furnace regulated to raisethe control ’s temp erature at a roughly uniform rate . But to makecertain of all this one has to turn to prevIous literature .

E . B . BAILEY .

THE CHANNEL ISLANDS . By JOHN PARKINSON . Handbuch der

region alen Geo logie , vol . iii, pt . i , pp . 335—41 . Heidelberg ,1 916 .

N Steinman n’

s Han dbuch der region alen Geolog ic, Mr . JohnParkinson gives a clear outline Of the Geology of the Channel

Islands, a subj ect to which he made formerly some valuable con trIbutions . It is illustrated by geo logical sections and small maps ofthe p rincipal islands . In Jersey the Oldest sedimentary rocks are

p robably Brioverian ,and in them are some “contemp orary vo lcan Ic

rocks,endingwith the remarkable rhy o lites of BoulayBay an d Anne

Port . Intrusive granites an d di orites also occur, the latter bemg the

4 2 Revi ews— Au stra lian A n tarcti c Exp edi ti on .

Older . There are some raised beaches, and a cave has y ieldedp alaeoliths of Mousterian age , an d nine human teeth Of p rimitiveNeanderthal typ e . Alderney consists of di orite, vary ing from a verybasic form to a tonalite, wi th a grit (gres fe lspathigue ) of earlyArenig age . Diorite

,tonalite, hornblende schist

,an d banded

granulites make up Sark . In Guernsey the southern an d largerp ortion is a somewhat variable gneiss, a p ressure - modified more orless p orphy ritic granite, the Oldest rock in the islands, the northernhalf being variations of diorite —basic, felspathic, an d quartzose_together with two small areas of granite . Mr . Parkinson retainsthe ' name hornblende gabbro , which was emp loy ed by Messrs . Hillan d Bonney in their p ap er on Guernsey in 1884 (Quart . Journ .

,vo l .

‘

x l ,

p p . 410 and but dropp ed after their work in 1910 (Quart .

Jo urn .,vol . lxviii, pp . 32—7) as they found it imp ossible to separate

p recisely the varieties of diorite, though convinced that some ofthem

, at an y rate, had once been augitic rocks . Dyke rocks occurin all the islands,an d in some mica—trap s are rather abundant .

These are p ost—Arenig , an d the greenstone , though rather older,is p robably the same . Microgranites are also found, some of whichseem to be p ost - Cambrian . The diorites, however, are p robablypre

—Cambrian, an d form a very interesting group of associatedrocks . As might be exp ected from their geographical position,the sedimentary and s om‘

e of the igneous rocks Of these islandsare n early related to those Of the adjacent mainland of France ,but the hornblende schists an d granulites Of Sar‘k are often indistin guishable from corresp onding rocks at the Lizard .

AUSTRALIAN ANTARCTIC EXPEDITION,

1911—14 SCIENTIFIC

REPORTS . Series C,Vol . “ IV, pt . iii Brachiop oda . ByJ . ALLAN THOMSON . With 4 p lates an d 1 map . June, 1918 .

PART I Of this memoir gives a systematic description of theB rachiop ods Obtained by the Australian Antarctic Expedition

p receded by an account Of what 1s known of the sp icules Of calcitefound in the body wall an d other p arts, together with some remarkson the punctation of the Shell . Sixteen sp ecies are described , an d are

referred to the genera Cran ia ,Herni

thyris, Liothyrella, Amphithyris(gen . Stethothyris, Gyrothp i s Mage llan i a Terebratella,

an d

Macandrevia .

Part II deals with the geographical distribution of the Brachiop odsof the Southern Seas . Twenty geographical districts are recognizedin the p art of the sea - flo or above the 1 ,000 fathom line , but inhalf of these no Brachiop ods have y et been found , SO that futurediscoveries may necessitate modifications in the conclusions drawnfrom the distribution of the small number of Sp ecies at presentknown. Only one sp ecies is common to two of these geographicaldistricts all the other sp ecies are confined to Single districts .

‘

The author p oints out the resemblance between the recent

Revi ews— P etr o logy for Studen ts .

’

43

Brachiop od faunas of these districts and the fossil faunas found inthe Upp er Tertiary of the neighbouring lands . Thus the recentNew Zealand fauna is a diminished representative of the Oamaruian

fauna the recent Australian fauna (excepting the subtropical parton the north - east coast) is a remnant of the Australian Miocenefauna o f

“ that continent . The Antarctic recent fauna is least like theTertiary fauna of that district, owing to the p resence of recentnorthern immigrants (Macan drevia ,

Frie leia ,Mage llan iaThe author concludes that the distribution of the recent brachiopods

in the Southern Seas is exp lained by the ancestral distribution inthe Miocene period

,and that it calls for no shallow- water connexions

between the various southern continents and islands Since thatdate, excep t p erhaps between South America an d . the Antarctic .On the other hand

,the resemblan cesbetwe en the Oligocene—Miocene

faunas of the four regions named indicate the existence at an earlierdate of greater means of communication between the landsbordering the Southern Pacific Ocean than exists at the p resent day .

The genera Argyrotheca,Amphithyris, Kraussin a ,

and Megerlin a

are found in the New Zealand an d Australian districts, but n o t

in the Antarctic an d South American ; as these genera occur alsoin - the Indian Ocean and the Mediterranean the author suggeststhat Australia had former connexions with South Africa an d theMediterranean . Dr . Thomson states that the molluscan faunas ofthe Patagonian Of South America and the Oamaruian of New Zealandg ive evidence of a much warmer climate than is found at presentin these regions . The occurrence of some Species and genera ofBrachiopods in the Oligocene—Miocene of the Antarctic which are alsofound in the Patagonian, the Oamaruian ,

and the Miocene ofAustralia suggests a warmer climate for the Antarctic seas of thatperiod .

The author urges the desirability Of further dredging on thesubmarine banks of the Southern an d Pacific Oceans ; if thesebanks are due to the sinking of land masses the remains of coastal 'faunas should be found on them . The concluding pages Of the workg ive a brief account of the diastrophic history of New Zealand .

The map of the Antarctic an d Southern Oceans shows theand fathom contours .

PETROLOGY FOR STUDENTS . By ALFRED HARKER,M.A .

,LL .D . ,

F.GS . 5th edition, revised . pp . 300, with 100 figures .

Cambridge University Press, 1919 . Price 88 . 6d. net .R . HARKER has been enabled during the comparative freedomfrom the burden of teaching afforded by the War to prepare

a fifth and further revised edition Of his standard textbook.

Oi

p etro logy ,whi ch is too well known to require a detailed n otICe

here . Considerable parts of the work have been rewr1tten ,an d the

results of all important recent wo rk is incorporated . The author

44 Revi ews— In ver tebrate Pa laeon to logy .

has made use of the work of British p etrologists Since the issue ofthe fourth edition in 1908, an d has found it possible to illustratemost of the imp ortant rock - typ es by examp les drawn from homean d from the British Emp ire . Besides n ewmaterial there is a certainamount of rearrangement , noticeable esp ecially in the chap ters onnepheline - sy enites and phonolites an d in the section devoted tometamorphism . A number of new figures have been added , bringingthe total to 100 . These are a most useful feature of the book, an dit is unfortunate that some of them have been printed Off for thisedition in a manner that fails to do jus tice to the beauty of theoriginal drawings . We are glad to observe that Dr . Harker’s bookis still sold at a p rice that brings it within the reach Of every student ,while to the advanced worker it is equally valuable as a work ofreference an d standard authority on its subj ect .

PALZEONTOLOGY (INVERTEBRATE) . By H. WOODS,M.A . , F.R .S.

5th edition . pp . 411 , with 173 figures . Cambridge UniversityPress, 1919 . Price 123. 6d. net .

ALTHOUGH this fifth edition of Mr . Woods ’s book is ap parentlysmaller than the last

,it actually contains 23 more pages and

24 fresh figures . It has been revised throughout, additions an dmodifications being made in most parts of the work . The sectionon the Asterozoa has been to a large extent re written ,

SO as tobring it into accordance with the recent work of Dr . W. K . Spenceron Palaeozoic starfishes . A revised account is given of thedistribution of marine mollusca at the p resent day . In the sectiondevoted to the Trilobites account is taken Of the recent work ofWalcott on the app endages and Of Ruedeman n on the medi aney e . The account of the Malacostraca has been amp lified, and theclassification of Calman and other" recent writers adopted . The

work of revision must have been difficult owing to the extensiveadditions to the literature of almost every group of invertebratessince the appearance Of the fourth edition , and the author is tobe congratulated on the successful manner in which he has dealtwith this . It is to be regretted that enhanced cost of productionhas made such a considerable increase in the price necessary ,

Sincesome students of geology may thereby be deterred from buy ing thisIndisp ensable work .

REPORTS AND PROCEEDINGS.

GEOLOGICAL SOCIETY OF LONDON .

November 19,1919 .

- Mr . G . W. Lamplugh , President, inthe chair .

The following communication was read : The PleistoceneDep osits around Cambridge . ” By Prof . John Edward Marr,Sc .D . , V.P .G S.

Rep orts (b Proceedi n gs— Geo log i cal Soci ety of Lon don . 4 5

This pap er deals with the dep osits in the immediate vicinity ofCambridge, and contains new re cords Of sections, fossils , and

imp lements . It is p ointed out that owing to alternating p eriods oferosion and aggradation, .relative height above sea - level is not atrustworthy index of antiquity , an dmodifications of the classificationprop osed by W. Penning an d A . J . Jukes—Browne are indicated .

The author suggests the following chronological sequence,in

descending orderFeet.

1 . Barnwe ll Station Beds 20

2 . Newer Down ing Site Beds 35

3. Newer Barnwe ll Village Beds 454 . Hun tin gdon Road Clays 70

5 . Observatory Beds 85

6 . Corbicu la Gravels (Barnwell village , etc . 30

The figures on the right give the approximate height abovesea l .evelIt Is believed that NOS . 6 and 5 were formed during a p eriod of

aggradation , an d 4—1 during one of subsequent erosion with minoraggradation but it cannot be conclusively proved that 6 and 3 are

of different ages , although the dep osition of the beds 6 below thoseof series 3, where they occur together, an d the occurrence ofHipp op otamus an d Belgrandia margin ata with Corbicula suggestan early date for these Corbicula bearing beds .

Taking the beds in the order Of reputed age , the followingobservations are notedChellean imp lements have been found at low levels at Barnwell

an d Chesterton, an d may belong to beds 1 . The ObservatoryBeds have y ielded abundant imp lements of Chellean , Acheulean ,an d early Mousterian typ es, the last - named apparently in dep ositslater than those containing the two first- named . Unfortunatelymollusca and mammalia are very rare in these beds . The HuntingdonRoad Clays re quire further work, as only poor exp osures havehitherto been found

,an d it is not clear that they are

,newer than theObservatory Beds .

The beds referred to the Newer Barnwell Village Series containabundant remains of the mammoth, woolly rhinoceros, and fairlynumerous horse - bones . Imp lements associated with them suggestan Up p er Palaeolithic age .

The Newer Downing Site Beds have y ielded a cold molluscanfauna . They are p robably somewhat earlier than the BarnwellStation Series, which has furnished a similar molluscan fauna,

and

also an Arctic flora,the plants of which were identified by the late

Mr . Clement Reid . Reindeer occurs in these beds .

The pap er is chiefly a record of facts,but it is intended to be

p reliminary to a detailed survey Of the Pleistocene dep osits Of theGreat Ouse Basin , which are so imp ortant as throwing light up onthe relationship Of the Palaeolithic beds to the glacial accumul atio ns,and also to the marine beds of March an d the Nar Valley .

46 Rep or ts (It P roceedi n gs— Geo log i sts

’

A ssociati on .

Appendix I, on the Non - Marine Mollusca,is supp lied by A . S.

Kennard,F.GS .

,and B . B . Woodward, F;G.S.

Lists are given of the non—marine mollusca from the varioussections, with their degrees of frequency . These lists are based onexamination o f

'

Old collections and on a large amount of newmaterial . Notes are app ended on some of the Sp ecies, an d conclusion s as to the ages of the Cambridge grave lS are given, basedon the molluscan evidence .App endix II, on the Imp lements, is supplied by Miles C.

.Burkitt,MA .

GEOLOGISTS’ ASSOCIATION .

December 5 , 1919

The following lecture was delivered : Geological Work on theWestern Front . By W. B . R . King , B .A .

, F.G S.

A short description was given of the geology -

Of that part ofBelgium an d France over which military Op erations were conductedby the ' British armies between 1915 and the summer of 1918 .

It was mainly confined to the lithologi cal divisions and did n o tdeal with the palaeontological side of the subj ect . The main physicalfeatures were taken

,showing how they are Connected with the

geological, structure .The effect of the geology an d the geological structure on certainquestions Ofmilitary Op erations were dealt with , notably with regardto water supp ly an d military mining an d dug—Out construction .

Particular attention was paid to the p roblem of obtaini ng water fromboreholes in the Lan den ien (Thanet) Sands, the causes and effectof the seasonal variation of water - level in the Chalk

,and the p roblem

of the military mines near Messines, Givenchy - les - la - Bassee, andSouchez .The lecture ended with a description Of certain maps which were

p repared for the armies in France,an d notes on several other

p roblems which had to be dealt wi th by the geologists attached toGeneral Headquarters .

LIVERPOOL GEOLOGICAL SOCIETY .

November 11 , 1919 — W. T . Walker,Esq.

,B .Sc .

,F.GS .

,President,

in the chair .The following communications were read : The Contributionof a local Geological Society to a Regional Survey .

” Marl an dMarling in Cheshire . By William Hewitt, B .Sc .

The idea of a fairly comp lete systematic survey of a districtcomp rising its physiographical and geological features, its climaticrecord

, its botanical an d zoological p opulation an d distribution, itsethnographical and archwo logical history , its agricultural an d

industrial conditions an d their evolution— as the basis of a carefully planned scheme Of development for the district as a whole ,

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4 8 Corr esp on den ce—The Sgurr of Eigg .

by Koenig in 1818, and therefore is not p receded by ProteosaurusHome , 1819 .

J . ALLAN THOMSON .

DOMINION MUSEUM, WELLINGTON, N. Z .

October 3, 19 19 .

THE SGURR OF EIGG .

SIR,

—My attention has been called to this“ time - honoured controversy by the contributions to the subj ect by my friends Dr. Harkera n d Mr . E . B . Bailey .

In 1898 I map p ed the Sgurr very carefully on the scale of‘6 inches t o the mile, an d obtained a good deal of evidence thathas not y et been published .

For instance, there are p ebbles of granite in the Bide in Bo idheachconglomerate, granite of a

' Tertiary typ e an d resembling none Ofthe older granites in Scotland . This certainly suggests that theconglomerate or breccia is of late date an d n ot of pre - dolerite age .

The dolerite sill (if it be a sill at all ) at“ Bidein Bo idheach does notturn upwards at the junction, but is cut Off abrup tly . The basaltdyke at the same place is also cut Off, in my op inion . I have nevers een an y fragmental dep osit that could stop a basalt dyke thathad p ierced through “

a succession of lavas .

I made many observations Of the inclination of the base of thep itchstone , an d ‘there is no doubt that rock occup ies a very distinctan d deeply cut groove in the basalt lavas and dolerite sills .

Incidentally I may mention that in my “

Op inion the Sills are far

fewer than Dr . Harker would suggest .The bottom breccia at the base Of the Sgurr (eastern end) I tookto be,as Dr . Harker says , part of the p itchstone, but not intrusive .

As I read the evidence,it is the brecciated base of the flow over

which the rest flowed . It has picked up fragments of basalt, sands tone , wood, etc , an d rolled along under the main mass . A coatingOf glass rouIid basalt fragments IS quite to be exp ected . I have neverseen an y intrusion that acted m quite the same way ,

though I haveseen igneous breccias formed at the edges of intrusions .

I left Eigg quite convinced Of the general accuracy of SirArchibaldGeikie ’s theory , an d nothing that I have read since has induced me

to Change my op inion .

Dr . Harker’

s. theo ry rests on too many theoretical considera

t ions ; Sir Archibald Geikie’s theory ,esp ecially as champ ioned by

Mr . Bailey ,rests chiefly on field evidence . In such cases , from a

long an d very varied exp erience of fie ld work al l over the world ,I naturally give the greatest weight to field evidence , an d thoughI do not wish to belittle an y of the microscop ic evidence “ thatDr . Harker has brought forward nor to disregard an y of thea rguments he has advanced , I cann ot accep t his theory .

E . H. CUNNINGHAM - CRAIG .

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DR . A . SM ITH \VOODW ARD , F .R . S .

FEBRUARY, 19 20 .

EDITORIAL NOTES . .

ORIGINAL ART ICLES .

An Inverted Mass o f Upper Cretace ous Strata n ear Le ighto nBuzzard . By F . L . KITCHIN an dJ . PRINGLE . (With a Textfigure . ) (Con tin ued )

Quartz ite Pebbles of the Oldhave nBeds . By H . A . BAKER . (WithPlate I . )

The Chin e s’

an d Cliffs o f Bourn emouth . By H . BURY . (With4 Text- figure s . )

A Quartzose Con glome rate at

Caldon Low , Sta-fi e . By F .BARKE ,W . HIND , an d A . SCOTT .

(With a Text- figure ) .

tEVIEws .

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H . C .

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“U Q

cc:

Fo ssil Plan tsThe In gredien ts o f CoalDifferen tiation in Ign e ous Magmas

Palaeozo ic Fo ssils from VictoriaThe genus P laty strop hia,BlockMoun ta in s in New Zealan dEconom icGe o l ogy ofHaze lton B .C .

A idS'

in Practical GeologyTun gste n an d Tin in Burma

Cain ozoic Fo ssils from Papua

REPORTS AND PROCEEDINGS .

‘

Geolog ical So cie ty o i Lo n don

CORRESPONDENCE .

Dr . A . HarkerPro fe ssor T . F . Sibly .

OBITUARY .

co

co

co

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Man ufacture rs of Op tica l and Scie n tif ic In strume n ts ,

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GEOLOG I CAL MAGAZ INEVOLUME LV l l .

NO. II.—FEBRUARY, 1920 .

ED IT OR IAL NO TE

HE Editors have been much gratified by the kind response thatthey have received to their appeal for the sup port of geologistsboth at home and abroad in their endeavour to secure the continuan ce of the GEOLOGICAL MAGAZINE . Numerous letters havecome to hand from all quarters promisin g valuable assistance

,both

moral and material, in their campaign against the adverse conditionsthat at one time threatened the very existence of the Magazine .The Editors felt sure from the beginning that it was only necessaryto in form their friends of the critical situation in order to enlisttheir help , and this confidence has been abundantly justified, so

much so that it is now possible to look forward to the futur e withsome degree of assurance, although it is still clear that the margino f safety i s not yet adequate to ensure against diffi culties arisin gfrom a further p ossible increase in the cost of production . Thes trictest economy will still be essential in every way . Itmay perhapsclear the air and avoid an y possiblemisunderstanding if it is g enerallyunderstood that the editorship is now a labour of love

,at an y ratein the sense that it is n ot remunerated . It is hoped that this con

dition is only temp orary ,and that it may in a while be possible to

revert to the former state of affairs, but at p resent even a smalleditorial salary is inconsistent with the continuance of the Magazine .It is, of course, imp ossible to cater wi th equal success for all tastes ,and the Editors can only do what they think will give most satisfaction to the maj ority of readers . Although a certain amount ofcriticism has been received , y et this is far outweighed by the mass

Of favourable comment coming from many quarters, for whi ch theEditors are duly grateful .

A SPECIALLY pleasing feature has been the active support Obtainedfrom sources outside this country ; from the British Domini onso verseas

,and especially from the United States of America . Kindlyletters have come to hand from South Africa . New Zealand , andmany

other countries where geology flourishes . But the best news of allcomes from America . On New Year’s Day a cable was receivedfrom Boston

,stating that the Geological Society of America has

guaranteed to find forty new subscribers for the present y ear . ThisVOL . LVII .

— NO . n .

50 Edi tor i a l Notes;

great assistance we owe largely to , the efforts of our kind friendsan d contributors, Dr .

“ J . M . Clarke,of Albany ,

an d Mr . P'

. E .

Raymond, ofHarvard , to whom we hereby ten der '

our hearty thanks .

It is events of this kind that encourage us to carry on in the “hop eof p romoting that worldwide exchange of geological thoughtwhich we have so much at heart, and which we firmly believe tobe so beneficial to the science of geology in general and to individualworkers in particular .

THE Coun cil of the Geological Society has this y ear awarded itsannual Medals an d Funds . as follows : The Wollaston Medal toProfessor BarOn G . J . de Geer

,of Stockholm,

Whose work is so wellknown to all geologists, an d esp ecially to glacialists , as to need n ofurther reference here ; the Murchison Medal to Mrs . Shakesp ear , _

formerly Miss E . M . Wood , the collaborator with Miss G . L . Ellesin their great work on graptolites an d the author of “

many pap ers onPalaeozoic stratigraphy the Ly ell Medal to Mr . E . Greenly , whoselong awaited memoir on Anglesey We hop e will soon se e the - light ;theWollaston Fund to CaptainWi B . R . King , late Of the GeologicalSurvey an d now Assistant to the Wo odwardian . Professor at

Cambridge, whose geological work on the Western front has latelybeen mentioned in our p ages ; the Murchison Fund to Dr . D .

Wo o laco tt, a recent an d valued contributor to this Magazine , whohas sp ecialized on the geology of: North - Eastern England ; “ whilethe Ly ell Fund is divided between Dr. J . D . Falconer and Mr . E S .

Pinfold,who have In recent y ears been working In Nigeria and

India resp ectively .

44

AT a recent sitting Of the No n - Ferrous Mining Committee Of theBoard of Trade some interesting evidence was given with regardto the p resent p o sitio n a nd prosp e cts

'

o f lead and zinc mining inthe Halkyn district of Flintshire . Most of the mi nes in the districthave now been worked almost

_down to the level of the existing

drainage tunnel , and working below this is obviously imp ossible,owing to the great volumes of water running through the Carbo ni ferous Limestone, as the writer can testify from recent exp erienceunderground in that region . A large scheme is on foot for a drainagetunnel at or near sea - level

,which would unwater a considerable

additional dep th of rich veins . Such an undertaking is as a rule to olarge for any single company to tackle successfully ,

but there seems

to be no p ossible doubt that judicious co - op eration as sisted by a

subsidy from public funds would result in great develo pments inthis district,Where the veins are undoubtedly very rich an d miningin the past has been very successful . The recent rise in the p rice

of the metals concerned foreshadows a p romising future for thisinteresting area,if the difficulties alluded to above can be success

fully overcome, and there seems to be every p ossible reason why a

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ORIGINAL ARTICLES.

O n an . In ve rte d Mass O f Up p e r Cre tac e o us Strata n e ar

Le ighto n Buz z ard, Be dfo rdsh ire an d o n an Ove rlap

o f the .Up p e r Gault in that Ne ighbo urho o d.

By F . L . KITCHIN ,M.A .

,Ph .D .

,an d J . PRINGLE ,

(Con tin ued from p .

B . COMPARISON WITH OTHER SECTIONS IN THE DISTRICT .

I . Section s n ear Leighton Buzzard.

WE owe to Mr . Lamp lugh a description of the lowest beds o f theGault and their junction with the Lower Greensand, as seen in

sand—p its on the south Side of Leighton Buzzard .

1 Mr . Lamp lughp roved the p resence of the fauna of the mammi llatas zone an d

found that.the fossils p reserved in the n tty phosphatic nodules

o f the lowest bed above the false—bedded ‘

sands in clude Don vi lleiceras

mamni i llatl

um (Schloth. ) an d the characteristic Desmoceras usuallyassociated with it .

2

In May of last y ear an excellent section, comp rising Lower Greensand and Lo ‘wer Gault

,was Shown in a sand -

p it (Mr . Webster’s)about 200 yards south of Billington Crossing (No . 1 ) on the LeightonBuzzard—Dunstable - railway (L . N This old excavationwas reop ened at the end of 19 18 an d has n owbeen abandoned . At

the time of our visits the beds exposed were as follows

Green ish -

grey stiff lumpy clay with a few smoothskin n ed nodules . NumerOus fragmen ts o f

ammon ites o f the in terrup tus - typ e occur mainlyin the form of casts aboutBrown ish san dy clay with streaks of glaucon ite

Thin ban d of dark -

grey clayPassage - bed to Dark - brown we‘ll - bedded san dy clay with numerous

Gault, roun ded quartz - grain s an d p ebbles . Pale - coateddark gritty phosphatic nodules of irregular shape(up to -6 in ches in diameter) , their surface studdedwith quartz - grain s , occur sporadi cally throughout about 4 0

Dirty brown ishwhite false bedded san d withban ds an d masses o f iron grit in lowest 5 feet .

Numerous thin brown rusty streaks occurp arallel to beddin g p lan es ; the san d p aler incolour at the top seen to 9 O

1 G . Wf Lamp lugh, Rep ort o f _ an Excursion to Leighton BuzzardProc. Geol. Assoc . , vo l . xxvi, p t . v , 19 15 , p . 310 .

2 Specimen s o f the Desmoce -

ras were submitted to on e o f the p resent writersan d were iden tified by him ; but he is n ot re sp on sible for the n ame un derwhich they were cited In Mr . Lamp lugh s rep ort (op cit. p . For a furthe r

accoun t of the sp ecies se e A . J . Jukes Brown e, The Cretaceous Rocks of Britain ,

vo l . i , The Gault an d Up per Green san d of Eng lan d (Mem . Geol. Surv . 1900,

p . 443 ; also G. W. Lamp lugh F. L . K itchin , On the M esozo ic Rocks in

some of the Coal Exp loration s i n Ken t (Mem . Geol. 19 1 1 p . 100 .

I n ver ted Mass of Up p er Cr etaceous Strata. 53

A Similar but less comp lete Section of the beds overlying theLower Greensand IS to be seen at the eastern end of the sand - piton the north side of the level - crossing (NO 2) .The following are some of the fossils collected by us from thetardeju

'

rcata bed of these two pits : all , with the excep tion of a sin glesp ecimen of the Desmoceras

,found half - way “up in the bed, were

encased in the rough - coated nodules .

T erebratula sp . Desmoceras aff . beudan ti

Exogyra con ica (J. Sow. ) Douvi lleiceras mammi l latumPan op ea sp . Leymeriella regularis

P ecten (Syn cyclon ema) orbicularis L . tardefurcataJ. Sow. Son n eratia dutemp lean aP . (Neithia) sp .

The most significant of these fossils are the species of Leyrn eriellaand Son n eratia

,which have hitherto n ot been recorded from an ylocality In this country . These or o ther sp ecies of the Leyin ericlla

fauna mark a definite zonal subdivision In certain districts on theContinent (Ardennes, South Eastern France, an d Brunswi ck);3occurring in association with Douvi lleiceras mammi llatum,

butmarking a time - period prior to the introduction of the in terrup tusfauna . The mammi llatus bed at Folkestone

,as in the

{n eIghbourl n g

part of France, contains elements of the in terrup tus - fauna,but no

sp ecimen of Leymeriella has been recorded from ,it . It therefore

seems highly probable that the zonal representation is imperfectin that region, and we may conclude that the passage from LowerGreensand to Gault is more clearly demonstrated at LeightonBuzzard than at an y exposure in England hitherto described .

We think it - not unlikely that the sandy basement - bed of the Gaultat West Dereham,

Norfolk,

3 would also y ield the tardefurrata—faunaif it were thoroughly searched . Jukes Browne’S description of thelowest Gault at Clophill

,

4 east of Ampthill, conveys the same

suggestion .

It should be noted that no Sp ecimen of Belemn ites mi n imusor of an y ammonite o f the in terrup tus type was found in thetardefurcata bed , while In the higher part of the section n ot one o f

1 For figures an d descriptions se e C. Jacob , Etude sur quelques Ammonites “

du Crétacé Moy en Mem. Soc . Geol. Fran ce, Paléon'tologie, ‘

-No . 38 , 1907,

p p . 53—8 , p ls . vii , vii i .2 C. Jacob ,

“Etudes Paléontologiques et Stratigraphiques sur la Partie

Moy enne des Terrains Crétacés dans l e s Alp es Francaises et les Region s

voi sines ’Trav. Laboratoire de Géologie de la Faculté des Sciences de

l’

Un iversité de Gren oble , vo l . viii, fasc . ii , pp . 296—7. W. Ki lian,Letkea Geogn ostica , II . Das Me so zo icum, Bd . iii , Abth . i , Unterkreide,”Lief. i , 1907, p . 62 . G . Muller, ‘‘ Beitra

g;zur K en n tni ss der Un teren Kreide

im Herzogthum Braunschweig ”Jahrb . preuss . geol. Lan de san st. f1

"

1r 1895 ,vo l . xvi , p . 1 10, Berlin, 1896 .

3 J. J. H. Teall, The Potton an d Wicken Phosphatic Deposits (SedgwickPri ze Essay ), 1875 , pp . 20—2 . A . J . Jukes Browne, The Cretaceous Rocks ofBritain , vo l . 1,

“ The Gault an d Upp er Greensand of En glan d ” (Mem. Geol.Surv. 1900, p . 297 .

4 Op . cit. p . 285 .

54 F. L. Ki tchi n an d J . Pr in g le

the ammonites recorded in the above list was seen . Manyammonites were found In this upp er bed of clay , chiefly In the formof fragmentary casts ;but every one was aHop lites of the i nterrup tustyp e . Several sp ecies are rep resented, an d it is unnecessary for“ ourp resent purp ose to attempt to name them critically . They displayno greater diversity than is seen among a number of di stinct speciesdetermined alike as Hop lites in terrup tus (Bron gn . ) in the chiefpublic collection s . Belemn ites min imus List . also occurred, and

among the few imp erfect lamellibranchs found we recognizedPlicatula gurg itis Pict . Roux .

We believe that an almost comp lete passage from Lower Greensand to Lower Gault is Shown here . Although the dividing - linebetween the Lower Greensand and the tardefurcata bed is clearlymarked, an d has been described by Mr . Lamp lugh as a sharpjunction there is no appearance of an y considerable break in theseries . The contrast lies in the change from the cross- beddedcharacter of the sands below to the horizontal bedding , With accessionof the c lay - constituent, in the Overly ing bed . Thi s might be interpreted as merely p roclaiming a somewhat rap id transition to moretranquil condi tions of sedimentation . At Miletre e Farm (No .

however, the tardefurcata bed wi th gritty phosphatic nodules isseparated from the top of the cross - bedded Lower Greensand bya 6 ft bed of horizontally stratified fine sand of distinctivecharacter, indicating that there is probably a true stratal break at

Webster’s Pit,though not one of an y considerable magnitude .

A comp arison between the section at Webster’s Pit an d that inHarris ’S Pit at Shenley Hill thus demonstrates how strikingly theyare contrasted in all essential particulars . In the neighbourhoodof Billington Crossing there Is no Sign of the beds C to G of ShenleyHill ; that IS, the brachiop od bed, the basal Upp er Gault, the 1ronstone - bands

,an d the impure sands overly ing the silver - sands

The lithological development of the Gault Clay in the two sectionsis so different as alone to cast doubt on the identity of these bedsWhile a Study of the fossils proves that no correlation of any partof the ‘G‘

ault in the two localities is p ossible .II . Section s n ear Shen ley Hi ll .

Sections in the neighbourhood of Shenley Hill show that there ,also the relations between the Lower Greensand an d the Gault aredifferent from those seen atBillington Crossing .

1Only at one locality ,

a p it on the north side of Mile tre e Farm (No . have we found thetardefurcata bed above the false bedded Lower Greensand . In thesame remarkable section the Upp er Gault 1s seen to rest discordantlyupon these earlier beds . Farther to the west, the Upp er Gault ,

1 The di fferen ce was remarked up on by Jukes Brown e, who p oin ted out

that south o f LeiOhton Buzzard there is a g radual p assage down to LowerGreen san d, While in this more n ortherly deve lopmen t there is n ot. The

Cretaceous Rocks'

of Britain , vo l . 1,“ The Gault an d Upp er Greensand of

Englan d ” (Mem. Geol. 1900, p . 284 .

I n verted Mass of Upp er Cr etaceous Strata . 55

with a well - marked basement - bed , overlaps on to the currentbedded Lower Greensand .

At the p resent time development is proceeding actively in thesand - workings of this neighbourhood . New op enings are beingmade and progress in excavation i s so quick, both l n these an d In

older p its, that n ew geological information is made available withina short interval of time . The stratigraphical relationships Showrap id lateral changes in this vicinity , owing to the Upp er Gaulttransgression an d the active erosi 'on which accompanied it . Forthese reasons the detailed descrip tion of a section studied on a '

givendate may not be strictly app licab le in the same p it at a later time .The fo llowin g was the section seen in October last towards thesouthern end of the western face in the p it n orth of Miletre e Farm(No . 8)

Soil an d subsoilBrown an d mottled sand with thin hardened

calcareous streaks along the beddin g ' the top6 in ches with many p ebbles an d rounded gritgrains 3 0

Passage - beds to Crowded fiat p ale brown horizontally di sp osedGault, clay stone nodule s, con tainin g minute traces of

with p lan ts an d with extern al films of secondarytardefurcata limoni te

n odules. Pale - brown san d with roun ded quartz - grains an d

small p ebbles , darker in hue in lowest 2 feetan d with a few sp oradic, p artly in durated sandnodules an d p ale - coated dark gritty phosphaticnodules

Horizontally bedded fin e sands with streaks of

black clay ey san d, dirty silver - san d an d

thi n lay ers o f brown iron - stained sand ; ligniteassociated with the black clay ey lay ers a few

inconstan t brown ferrugin ous indurated courses ,2 inches l n thickness 6 0

False bedded white sands , iron stained in places ,with occasional scrap s of lignite seen to 18 0

The tardefurcata bed is here separated from the false - beddedLower Greensand by a well - characterized 6 ft . deposit . of sand ,many layers of which are p ecul iar by reason of their very finesmooth texture and by the alternation of lighter streaks an d darkcarbonaceous an d clay ey streaks . We recogni zed at once that thisbed shows a striking resemblance to the fine

,

’

similarly impure,sand of bed G in Harris’s Pit .

The overlying stratum may be correlated with the tardefurcatabed of Billington Crossing . We could not break open a sufficientnumber of the nodules to enable us to obtain an y of the characteristicammoni tes, although a few other fossils were found ;1 but the nodulesthemselves are identical in character with those found at Webster ’s

1 While worki n g at Billington Crossing we estimated that the y ield o f

ammon ite sp ecimen s in r elation to the number o f nodules broken op en i s

considerably less than 1 p er cen t .

56 F. L. Ki tchi n an d J . Pr i n g le

Pit and in the exposur e n ear to it Where this bed was seen . Theyhave the same pal e exteriors, roughened by protruding quartzgrains, an d the fractured surfaces of their interior parts Show thesame dark, compact, hard ground - mass of phosphatic materialenclosing rounded quartz -

grains and rusty specks . The overly ing6 in . bed of claystone - nodules an d the 3 ft . bed of sand at thetop of the section are developments not seen at Billington Crossing .

The series above the false - bedded sands is thus a fuller one atMiletreeFarm

,but the variation shown is just whatmight be expected tooccur under the conditions which prevailed p rior to the dep osition

of the deep er - water in terrup lus clay .

Towards the northern end of the western face In the same pit(No . 8) the whole of the above series of horizontal sandy bedsbecomes cut o ff obliquely by a mass ofUpp er Gault, showing a well:marked basement bed slop ing down towards the n orth (Fig .

The following is the section as examined at an - easily accessibleSpot

,indicated by an arrow on the figure

Soil with a few subangular flin tsLowest clay o f Upp er Gault, containing smallwhite calcareous n odules (up to 1 inch indiameter)

Impure yellowish brown earthy sandwith someadmixture of clay an d man y rounded quartzp ebbles (up to in . in diameter), an d with somewhite nodule s as in clay above also brecciatedfragments o f ironston e an d smooth roundedhollow p ebbles of iron stone ; an un dulatin g2 in . limon ite iron stone - band (of secondaryorigin ) at base an d a similar band at an d nearthe top , the two often broken an d di slocated,sometimes approaching each other an d becomingcon fluen t also“ thin, irregular in terlacingbranches o f tabular ironstone within the bed ;vary ing from 4 inches to

its undulatin g lower surface restin g un conformably on the

tardefurcata bed an d underly in g san ds, as seenin p revi ously de scribed section in the same p it.

Whi le the original constituents of the basement - bed of the Upp erGault include angular an d subangular fragments of limoniticironstone and many worn hollow p ebbles of ironstone, mostlyhaematitic , the thin tabular limonite - bands are evidently o f laterin troduction . They Show di slocation an d contortion, due to movements in the bed subsequent to their formation .

When traced towards the north within this p it the Upper Gaul teventually cuts across lower an d lower strata,until it comes in

contact with the current—bedded sands at the bottom of the p it .

Where this relation is shown, as in the northern face of the p it, theclay above the basement bed is p resent to a thickness of about8 feet

,the slop e of the ground—surface reducing what would otherwise have been a thicker mass of this clay . The basement bed and

the clay above, which dip towards the east in this face of the p it, are

In ver ted Mass of Upp er Cr etaceou s Strata . 57

relatively un fOssiliferouS . The fact that they are both characterizedby consp icuous small white nodules (white throughout) is a p omt

to be sp ecially noted, Since,owing to the rarity of fossils, the

p resence of these nodules is help ful in identify in g these beds l n othersections . Kingen a lini a (Defr . ) and a few poorly p reserved remaIn s

of other brachiop ods were found by us in the basement - bed here,but only Belemn ites min imus List . was seen in the clay above . The

characters of the clay ,which are constant wherever these beds

occur around Shenley Hill, will be noted below in our account ofa section in the abandoned Garside ’s Pit (NO . adjacent toHarris’s Pit .

IOYARDS

Ho r i z o n ta l a n d Ve r ti c a l Sca l e

FIG .—Diagram of the section in the western face o f the san d -

p it on thenorth side of M1letre e Farm (No .

6 . Soil.5 . Upp er Gault Clay .

4 . Basement - be d of Up p er Gault, coarse. material with thin bands o f

secon dary iron stone restin g un con formably on the Lower Greensand an dPassage - bed .

3. Passage - bed between Lower Green sand an d Lower Gaul t ; o f

tardefurcaI‘a - age . A few dark phosphatic nodul es an d some partly in durated

sand - nodules occur scattered in the lower p ortion there is a line of clayston e nodules above the middle.2 . Hori zontally bedded Lower Green sand ; fin e sand with clay ey an d

carbonaceous lay ers .

1 . False - bedded Lower Greensan d, n o t al l shown in the Figure .The age of the clay cannot be determined at Miletre e Farm,

where its higher and more fossiliferous part is not present . In

formation obtained at a section Where a fuller development of it isdisp lay ed (No . 9 ) shows that it must be ascribed to theUpper Gault .We have nowhere seen any exclusively Lower Gault fossil in it .The relatively steep north - easterly dip of the clay and basementbed shown on the north side of Miletree Farm is probably of quitelocal significance, an d is due to the fact that these beds rest on aneroded slop e of older strata . The occurrence of a rap id lateralchange is shown in the pit Situated just south of the farm (No .

Where the relations of the Upper Gault to the underly ing beds are

58 F. L . K i tchi n an d J . Pr i n g le

indeed surp risingly different . The 6 ft. bed of fine horizontallybedded Lower Greensand an d the 8 ft . bed of passage strataoverly ing it, seen north of the farm ,

are absent . In the northernface of this southern pit the Upp er Gault rests di rectly upon“ thefalse - bedded Lower Greensand . The peculiar basement - bed of thenorthern p it is p resent here, [but is separated from the underlyin gcurrent—bedded sands by one foot or so of obscurely bedded ratherdingy grey - brown p ebbly an d gritty san d with p oli shed grain s .

This contains some of the characteristic phosphatic nodules of thetardefurcata bed, seen in p lace north of the farm . . This thin depositof sand is evidently a p roduct of the denudation of the tardefureatabed (se e Fig . which is situated at a higher level . Its p ositionjust above the false - bedded sands , as well as the p resence in it ofthe small white nodules which characterize the basal beds of theUpper Gault here , shows that it belongs to the period of the transgressio n . The clay above the basement - bed is present to the extentof 4 feet in thickness . It contains the small white nodules , but -differsfrom the corresp onding clay seen north of the farm by the presencein its lower part of numerous highly polished quartz—p ebbles, up tohalf an inch in diameter .At the west side of pit No . 7

,the lowest clay of the Upper Gault

is overlain by some imp erfectly bedded, crumbled, grey clay, whichis met with in other sections about to be described . At the

southern end of the pit the false - bedded Lower Green sand crop s outat the surface, and no Gault is p resent . The grey clay justmentioned,

which overlies the lowest 4 feet of Upp er Gault Clay ,is of a peculiar

type an d is readily recognizable in the other sections where it hasbeen seen . It is a soft clay wi thout an y well—defin ed bedding - planes ,an d is made up of innumerable small p ellets, which are for the mostpart somewhat angular in shap e . It might be termed a finelybrecciated clay . We think it most p robable that the materialof which - it is comp osed is the redep osited debris resulting fromthe denudation of s ome p reviously formed, well - consolidated clay .

It is relatively unfossiliferous, an d app ears to contain no ammon ites .

Here an d there it contains small pockets of glauconite, with someof which a few sp ecimens ofBe lemn itesmi n imusList . are associated .

It is evident that at Miletre e Farm the upper beds of the LowerGreensand, with the passage - beds at the top ,

were subj ected toerosion under the action of strong currents . They stood up hereon the sea - flo or as a bank of consolidated, though soft

,horizontal

strata,the slop ing sides of which were being planed away . While

the fine, lighter material of the 6 ft . bed of sand underly ing the

tardefurcata bed would, under such conditions, be swep t away bycurrents

,some of the nodules and heavier sandy materials of the

tardefurcata bed found their way down the slop e an d, as a residueof the local denudation

,formed a constituent of the basal deposit

of the Upper Gault . An almost identical section , Showing the rearranged sand 1 foot ' thick (with nodules from the tardefurcata

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60 F. L . Ki tchi n an d J . Pr i n g le

It is necessary to look further before the local correlation of thesection in Harris’s Pit can be comp leted . In a long - abandonedp it situated at about 900 yards north - west of that locality an d some300 yards north of Shenley House (No . the Upper Gault Clay isp resent to a thickness of about 20 feet . Here the lowest beds,as above described in the section at Garside

’

s Pit, were found insimilar development overly ing the indurated top of the currentbedded Lower Greensand thus , a basal bed consisting of y ellowi shbrown an d greenish clay ey sand with some p ebbles (and with ironstone courses) , here less than a foot in thickness ; the clay aboveit containing white nodules, red - stained at its base ; and the

succeeding crumbled an d imp erfectly bedded grey clay . Above thelowest 8 feet of clay the section is entirely obscured by slip s, but ata distance of about 15 feet above the basal bed a p ale marly claywith blocky fracture y ielded numerous fossils . These includeabundant sp ecimens of Sckloen bachz’a varicosa (J . de C. Sow. ) anda well - keeled Sckloenbachia simi lar to one found near the top at

Harris’s Pit a Hop lz'

tes showing a smooth stage in an auritus - likestock ; another sp ecies of the sp lenden s typ e (in the broad sense)In oceramus con cen trieus Park ,

an d numerous large examp les o f

In oeeramus sulcatus Park . This assemblage indicates a p ositioncorresp onding wi th Red IX of Price at Folkestone , an d with theclay showing similar lithological an d faunal characters at the topof Harris ’s Pit .

Since the Gault below this fossiliferous bed, at“ the locality justdescribed, shows such a marked contrast in all its characters to the :beds now in corresp onding position at Harris’s Pit, there are n o

grounds for correlating them . If the mass of Gault in Harris’s Pitwere in a normal p osition this contrast would be difficult to explain .

Since we have shown it to be inverted the exp lanation is simple .The beds there below the clay containing In ocemmus sulcatus and

Sckloenbackz’

a varicosa rep resent a still higher part of the series , ofwhich a portion,only a few feet thick, is present at the top of the

section n orth of Shenley House .We infer that the Gaul t in situ at Shenley Hill was originally

some 40 feet thick at the most an d we consider that the presenceof the fauna of Bed IX of Folkestone such a short distance up inthe series makes it certain that only the Upp er Gault is rep resented.

here . This reading of the facts is supp orted by the ascertainedthickness of the formation where it is fully develop ed farther tothe south

,even when allowance is made for a general thickening

of the sediments in that direction .

The evidence thus shows that the date of the overlap may wellcoincide app roximately with that of the Middle Junction Bed .

(VIII) at Folkestone . The character of the lowest bed is such as .

would result from its formation upon a sandy bottom in shallowwater under the action of relatively strong currents . The transgression would imp ly a deepening of the sea - floor, so that these :

I n ver ted Mass of Upp er Cretaceous Stra ta . 6 1

coarser sediments soon gave p lace to the succeeding clay . L ocally ,

as we have noted at one of the pits at Miletre e Farm,the clayimmediately above the bottom bed contains p ebbles, a sign of continned current - action at that spot . Evidence for the existence of

an overlap of in terrup tus or later date has been referred to byDr . A . Morley Davies,1 while Professor Kilian has pointed out thewidespread . character of the transgressive movements proved tohave occurred in Upp er Gault time . 2Another section in this neighbourhood is less easy to interpret .This is the brick - pit, situated yards to the southward ofHarris’s

Pit (No . from whi ch Jukes - Browne recorded a number of Upp erGault an d Lower Gault fossils .

3 There was at one time an exposurehere showing 10 feet of clay with a seamof nodules about the mi ddle ,from which the fossils were said to have been obtained . This p ithas long been di sused an d is now so overgrown an d flooded as tog ive no information . Mr . Lamplugh used Jukes - Browne’s accountof this exposure in support of the contention that the clay atHarris’sPit above the brachiopod - bed is of Lower Gault age . Indeed

,this

seems to have been the only' item of evidence which he was able tobring forward as the basis of the following imp ortant statement :We must therefore conclude that the overly ing clay in the sand

p it sections represents Lower Gault, and that the fauna of thecalcareous masses is of earlier date . ” 4

Now it is clear that if the fossils recorded in Jukes- Browne’slist were correctly identified , the nodule - bed in which they occurreddoes not belong to the Lower Gault ; it must be of rostratus age .

If the Lower Gaul t fossils trul y came from the same bed of nodulesthey must have been derived if they did not come from that stratum ,

then it is conceivable that beds of in terrup tus - age are present atthis lo cality , overlain by the unconformable rostratus Gaul t . Yetthe knowledge gained from the sections already described rendersit improbable that a 10 ft . section would include both these faunas .

No nodule bed similar to that described by Jukes - Browne has beenseen in any of the sections examined by us

,and we are unable to

test the value of his record . It is p ossible that the bed is p resentin the concealed part of the section - in the Upp er Gault 300 yardsnorth of Shenley House (No . 9 ) the character of the fossils recordedby Jukes - Browne is quite in keeping wi th such a position, corresp ondin g with Bed IX at Folkestone .The examination of the undisturbed Gault east an d west of

Shenl ey Hill shows that the higher beds of the Upper Gault, whichconstitutes the main mass of the hill

, stand up as an outlier, isolatedM. Davies 83 J. Prin gle, On two deep Borings at Calvert Station

(North Buckin ghamshire) an d on the Palaeozoic Floor north o f the ThamesQuart . Journ. Geol . Soc . , vo l . lxix, p t. ii , 19 13, p . 338 .

2 W. Ki lian Lethea Geogn ostica , II. Das Me so zo icum, Bd. iii, Abth. i ,

Un terkreide, Lief. i , 1907, p p . 6 1—125 .

3 A . J . Jukes - Browne , op . cit .

,1900, p . 285 .

4 G. W. Lamp lugh J . F. Walker, op . cit. ,1903, p . 246.

62 H. A . Baker— Quar tz i te P ebbles of the Oldhaven Beds .

from the general outcrop of Gault to the east and south - east . In

pre - Glacial times the high ground must have been capp ed by some

remnants of the basal Cenomanian bed , as shown by the fossiliferouslenticles p reserved at Harris’s Pit ben eath the inverted mass ofrostratus Gault .

From the information obtained from . the sections above dealtwith

, as well as from Mr . Lamp lugh’

s published records showing theformer occurrence of the brachiopod - lenticles (bed D) in parts ofChance’s Pit and Garside

’

s Pit, we can form some idea as to theoriginal size of the overturned mass of strata . A great part of ithas been destroy ed in .the course of the excavations, so that at thep resent time the remnant is only accessible for study at Harris’sPit . It may be roughly estimated that the mass formerly showeda north an d south extension of about 250 yards . The position of itsoriginal _ eastern boundary is more uncertain, but was probablyabout 150—200 yards distant from the present working face atHarris’sPit (se e Fig . It is imp ossible to say how much further to thewest the limit of the mass in that direction mi ght be p roved to occurif excavation were to be continued .

,

It is probable that its westerlymargin will not be reached in Harris’s Pit, a sand - working situatedin the slope of the hill with a thickening cover of clay . But thepurely local character of the inverted mass has already beensuffici ently demonstrated .

“

(To be con c luded . )

On the Quartz ite Pe bble s o f the O ldhave n (Blackhe ath)Be ds o f the So uthe rn Part o f the Lo n do n Basin .

By HERBERT ARTHUR BAKER . M.Sc . ,FMG S

(PLATE I . )

T is common knowledge to all geologists interested in the LowerEocenes of the southern part of the London Basin that, in the

Oldhaven (Blackheath) Pebble Beds, pebbles of a brown quartziteare often to be found on searching amongst the rounded flin ts ofwhich these beds are so largely comp osed . When geological partiesvisit section s exposing the p ebble - beds of“ the Lower LondonTertiaries, the search for these quartzites usually constitutes oneof the items of the fie ld - work to be don e . A considerable numberof these pebbles must

,by this time , have been collected, but ,

although their occurrence has given rise to a good deal of discussionan d sp eculation, nobody app ears, so far, to have undertaken a

systematic examination of their characters an d p etrological affinities .

The view has been prop ounded that the study of these pebbleswould throw light on the question of the source of the materialc omposing the Lower London Tertiary beds . In dealing with the

If . A . Ba lcer— Qa ar tzi te P ebbles of the Oldhaven Beds . 63

latter question , the difficulty confronting the geologist is that s incethe p ebbles of the Oldhaven Beds consist (excep t for the quartzites )entirely of rolled flin ts, an d since,where p ebble - beds occur in other

of the component members of the Lower London Tertiaries , theyare always comp osed of flin ts, it is naturally inferred that theChalk was denuded to furnish the material for these strata ,

butit is“ obvious that the Chalk alone could not have supp lied thearenaceous an d argillaceous material comp osing them . The hOp ehas therefore lingered in the minds of geologists that, sooner orlater, the parent - mass of rock from which these quartzites werederived would be located, and evidence concerning the source ofthe material of the Lower Eocenes be thereby gained .

Dr . G. J . Hinde, in the course of a paper o n the B lackheathPebble Beds of 'the Addington Hills, 1 referred to these quartzitesas follows : The only exception to the prevalent flin t-

p ebbleswhich came under my notice were some cake - shap ed p ebbles ofa light - grey quartzite, in form and smoothness of surface verymuch like the flin ts, from which , indeed, they could hardly bedistinguished until they were broken . These quartzites are veryhard and fin e -

grained . They appear to be rare . The largestI found was about 4g inches across by 2 inches in thi ckness (110 by45 mm. ) Judging by the character of the rock, they may havebeen derived from Palaeozoic strata,

an d it is not easy to accoun tfor their p resence in these Tertiary pebble - beds, associated as they arewith Chalk - flin t pebbles exclusively . I am not aware that similarp ebbles have been p reviously recorded in the B lackheath or Oldhaven series, but Professor Prestwich has lately stated that largep ebbles of white or light - coloured quartzite, now p resent in thebeds of Westleton shingle, may have been derived indirectly fromthe shingle - beds of theWoolwich an d Reading series

,where he has

occasionally found them,or they may have come from the quartzites

of the Palaeozoic rocks of the Ardennes .

”

In the discussion which has centred round these interestingp ebbles (based chiefly on the external characters p resented by them) ,Op inion has been divided . Whilst some have been inclined to adoptthe view ofHinde and Prestwich

,quoted above

,that these quartzites

may have been derived from Palaeozoic rocks, others have consideredthem to be sarsens If it be granted that a sarsen is a rockoriginally associated with , an d derived from

,Tertiary strata (n o t

necessarily of Upp er Eocene age ) , then the present writer regardsthese quartzite pebbles as sarsens, but it is not his intention at thisjuncture to labour the p oint, or to embark upon a plenary defin ition of the term sarsen It ' is here proposed simp ly to considerthese p ebbles as pebbles occurring in the Oldhaven (Blackheath)Beds .

With regard to their occurrence, these pebbl es are certainly rare,1 Hinde , Proc. Geol. Assoc. , vo l , x i , 1890, p . 467 .

64 H . A . Ba lcer—Qa ar tztte P ebbles of the Oldhaven Beds .

but not of such extreme rarity as has been supp osed . Theyare apparently always to be found where the B lackheath PebbleBeds are

,exp osed if the seeker has succeeded in cultivating the

n ecessary ey e for their detection, an d pursues his search withp atient assiduity . The writer has obtained them from the B lackheath Pebble Beds in the neighbourhood of Plumstead Common

,

an d at East Wickham , ,

Bostall Heath , an d Eltham . The pits at

East Wickham and Bo stall Heath have y ielded them in considerable number to various workers . Mr . A . L . Leach an dMr . R . H.

Chandler have obtained a good many from these two localities .

They have also been found at Charlton and Keston . The outliersof the North Downs have y ielded them . They have been foundat Worms Heath an d in the neighbourhood of Caterham . Theyoccur on beaches 1n the neighbourhood of the outcrop of the LowerLondon Tertiary beds . The writer has collected them 111 numberson the beach near Reculver, not far from Bishop stone Ravine ,an d also at Sho

l

reham (near Brighton ) an d at Dovercourt . Theydo n ot occur at Pegwell Bay , where the Tertiary cliff - section is inThanet Beds only .

In external app earance these pebbles bear a fairly close res' emblance to p ebbles of partially decomposed flint,but they p ossess

certain characteristics which, when well visualized, lead to theirready detection in the field . They vary in size, but are usually n ot

small,and are generally , though not invariably ,

characterized bya flattened ovoid shap e suggestive of their derivation from hardened ,tabular masses . They are usually very hard, capable of taking an d

frequently p ossessing , a more than ordinary degree of p olish . In

colour they vary from brown to grey or nearly white, being frequentlybuff or drab . A common feature is a mottled marking or patchycolour distribution . Another interesting typ e sometimes met

with exhibits a kind of wavy banding of darker and lighter colouredmaterial

,due, apparently ,

to a tendency .towards aggregation ofthe iron - oxides p resent . in the ro ck . The texture of the - rock

,as

e xamined on fractured surfaces with a hand—lens,is usually fin e

g rained, sometimes markedly so,but there is frequently con

siderable variation to be seen,often in one an d the same - sp ecimen .

There is often little app roach to uniformity ,the conversion of the

rock from sandstone or grit into quartzite having apparentlyp roceeded irregularly , so that the crystalline app earance of a

quartzite is seen only in patches, the remainder of the rock appearingas a fin e—grained saccharoidal sandstone . It is this variation intexture owing to the sp oradic character of the silicificatio n whichfrequently imparts a mottled appearance to the external surface ofmany of the p ebbles .

When the rocks are‘

sliced an d examined microscop ically its een that they are not metamorphic rocks at all

, in the strict senseo f the term . They have not been p roduced by either contact orregional metamorphism,

but fall within the class o f rocks resulting

H . A . Ba lcer— Quar tz i te Pebbles of theOldhaven Beds . 65

from the op eration o f what has been termed atmospheric metamorphism The rocks are really sandstones or grits which havebeen cemented as the result of ametasomatic change— the addition offresh silica as a cementing medium . The name quartzite as

app lied to the rocks , is legitimate by y irtue of the definition thata quartzite is a rock composed chi efly of quartz grains with theaddition of a quartz c ement . Yet, in view of the irregular an d

inconstant character of the cementation the ro ck may , with equalprop riety ,be frequently described as sandstone (where the grains

are well rounded) or _grit (where the grains have preserved theirangularity ) . It is frequently possible, in different parts of the sames lice, to app ly the names quartzite, sandstone , and grit “with equaljustification.

In all the slices examined by the writer n o evidence of secondaryo utgrowth from the quartz -

grains was to be observed, an d therewas no sign of op tical continuity between the original grains . and

the secondary silica . The latter was '

often amorphous, apparentlyc olloidal, and generally dirty with disseminated iron - oxides .

App roach to a quartz - mosaic structure was seen only rarely and

locally , and was but imp erfectly developed . Where observed,the interlocking grains were of small size , and the feature wasapparently developed only in the secondary silica . In the examination of the slices the p resence of other minerals such as tourmaline ,kyanite, stauro lite

,zircon

,rutile

, glauconite, felspar, and irono xides was noted . With a view to the further examination of theseminerals some of the p ebbles were crushed, and minerals p ossessinga sp ecific gravity of more than 2 80 were isolated by the use ofThoul et

’

s (Son stadt’

s) solution . It was then seen that the heavyresidue was comp osed essentially of the assemblage of minerals so

characteristic of the heavy residues of the Woolwich and ReadingBeds . The writer has recently examined a considerable number-of heavy residues from these beds, from various localities on thes outhern side of the London Basin, an d he has found the mineralassemblage to be one of remarkable constancy of character . Thenumber of heavy minerals occurring is not large, but the wholesui te is invariably p resent and the mi nerals always exhibit thesame individual characteristics and occur in the same relativeo rder of abundance . The assemblage of minerals (of . specificgravity greater than '

2 '

80) is chiefly characterized by the presenceo f kyanite, tourmaline

,zircon

,staurolite , rutile , ilmenite with

leucoxene, magn etite, limonite , and glauconite . Others, such as

c olourless garnet, haematite,py rite, anatase, and

_very rarelyandalusite

,occur . With regard to the glauconi te, which is always

p resent, no defini te idea of its degree of abundance can be arrivedat

,since the amount of iron p resent in the mineral appears to vary ,

an d the consequent variability of its sp ecific“ gravity governs i ts

behaviour in the heavy liquid .

The heavy residues from the quartzite pebbles were prec1se lyVOL . LVII .

— NO . 11 .5

66 H . A . Baker— ‘

Qu‘ar tztte P ebbles of the Oldhaven Beds .

similar to those from the Woolwich and Reading Beds . The same

minerals occurred , in the same relative order of abundance an dexhibiting the same individual features ,

in each case . No mineraloccurred

,which had not been noted in the Eocene residues, and, ofthe sp ecially characteristic minerals of the latter, there was n o

absentee in the residues from the quartzites . In view of this.

evidence it would seem that these pebbles are n ot foreign rocksderived from a distance an d incorp orated in the p ebble - beds, but.that they are closely related to the Lower Eocene beds .

In pursuance of this idea it becomes necessary to inquire into theevidence for the occurrence,in the Lower London Tertiary beds,

of material similar in character to these p ebbles, an d at once themuch debated greywethers or sarsen - stones are recalled .

Prestwich,as long ago as dealt in a full and admirable manner

with the question of the source of the Druid Sandstones and thearguments he brought forward are just as cogent to - day as theywere when he wrote . He concluded first from the then avai lableevidence, that the distribution of these Druid Sandstones was

more in a ccordance with the range of the Lower London Tertiaries .

than with that of the Bagshot Sands . Thi s conclusion has beenendorsed by . later workers . Prestwich then p roceeded to considerthe three members of the Lower London Tertiaries separately

'

as

possible sources of these sandstone blocks . He discarded theThanet Sands on the ground that although they often‘ presentfavourable elements and are occasionally semi—indurated, theyare rarely consolidated . In the - case of the section at the Reculvers,where the Thanet Beds contain a bed of concretionary sandstone ,he pointed out that the sandstone has a calcareous cement

,contains

no p ebbles , and frequently exhibits the imp ressions of shells ;whereas the erratic sandstones of Kent,Bucks

, an d Wiltshire areneither calcareous n or ffossiliferous

,and are not uncommonly sub

conglomeratic . He p ointed out,further

,that the T hanet Sands.

do not range more than 6 to 10 miles westward of London . He

next considered his Basement - bed of the London Clay ”

,with

which, at that time (1854) were included the present Oldhaven orB lackheath Beds . He alluded to the facts that the Basementbed p resents a very small development westward of London, an dthat although it often contains concretionary blocks they are

almost . invariably small, calcareo - argillaceous, an d fossiliferous .

He then stated his belief that the greater p ortion of the blocks.

known as Druid Sandstones, greywethers, sarsen - stones,

an d

puddingstones were derived from the middle division of the LowerLondon Tertiaries . He admitted that it was very rarely thatsolidified p ortions of the strata were found in situ, but stated thatthe same difficulty occurred in as great a degree with the sandstones o f the Bagshot Sands . He was able

,nevertheless

,to put.

Prestwich, The Woolwich an d Reading Series Quart. Journ . Geol.Soc . , vo l . x , 1854 , pp . 123—30 .

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68 H . A . Baleer— Quartztte P ebbles of the Oldha ven Beds .

Ostrea bellccactn a in the Woolwich Series to be encountered in a

silicified condition . This has been well seen in borings at WoolwichArsenal

,and also at Well Hall

,near Eltham .

’ The cementation ofthis bed is, however, frequently ferruginous in character . The sameis true of the indurat ed masses so often seen in the B lackheathPebble Beds of this district . At the large brick -

p it at South Bromleypatches of fli n t - pebbles cemented in a siliceous matrix have beenseen in p ebble - beds separated from the London Clay above by about20 feet of sands, clays, an d p ebble - beds, I but it app ears to be muchmore usual to find that where the Blackheath Pebble Beds are locallycemented into conglomerate, the cement is largely ferruginous incharacter . Such was the case, for instance, at the KidbrookeTunnel . 2 On Plumstead Common, near the bandstand, is a largemass of B lackheath Pebble Beds (an outcast mass from some veryold gravel - p its, now vani shed) firmly cemented into a hard puddingstone ‘

by a cement which is apparently more ferruginous thansiliceous .

On the Continent, in Belgium,and North France

,sarsen - stones

are of common occurrence in the beds equivalent to our Woolwichand Reading Series . Mr . L . D . Stamp ,

who has recently familiarizedhimself with the Eocene sequence in these areas, informs the writerthat the occurrence of sarsen - stones in the fluviatile facies of theUpp er Landen ian of Belgium an d the Sparnacian of the Paris Basini s a characteristic feature .At the present time it app ears that results afforded by inquiry

along three indep endent lines now p oint to a common conclusion .

In the first p lace, as the result of the search for evidence concerningthe origin of the sarsen - stones , it may now be taken as satisfactorilyestablished that the Woolwich and Reading Beds have affordedone source of supp ly . Secondly , study of the p etrology of the sarsenstones has revealed a close affinity between them and the materialof the Woolwich and Reading Beds . This question has been '

investigated by Professo r P . G . H. Bo swellf’ who found the mineral

suite o f the sarsen - stones to be precisely similar to that of theReading Beds, an d who concluded that the d istribution, mi neralconstitution

,and general characters of the sarsens indicates theirprobable derivation from the sands of the Reading Beds . Thirdly ,

as indicated above, the mineral suite of the quartzite - pebbles ofthe Oldhaven Beds p oints to a close affin ity between them an d thesands of the Wo olwich and Reading Beds . All that now app earsto be required is some definite piece of evidence indicating a directconnexion of the sarsen - stones with the Oldhaven quartzites , anda recent fortunate find of the writer’s apparently affords the necessaryconnecting - link . The photograph shown in the Plate (Fig . 1 ) iso f a rolled quartzite - pebble which the writer obtained in situ in

1 Summary o f Progress Geol . Surv . , 19 13, p . 29 .

2 T . V. Holme s , Proc. Geol. Assoc . , vo l . viii , 1893—4 , p . 154 .

3 Boswell, Quart. Journ . Geol. So c . , vol . lxxi, 19 15 , p p . 573—4 .

H . A . Baker— Quartzi te P ebbles of the Oldhaven Beds . 69

B lackheath Pebble Beds exp osed in a road - cutting on the easternside of Plumstead Common . In addition to showing all the usualfeatures of these quartzite - p ebbles, the p resent sp ecimen is speciallyinteresting in virtue of the fact that it contains -wi thin itself a largenumber of rolled flin t-

p ebbles . Numbers of the latter were exposedon the exterior of the pebble

,an d on fracturing it many

‘

more wereseen . Slices were p repared for microscopic examination, and. wereout so as to include some of the flin ts . Two mi crophotographs ofthese sections are shown (Figs . 2 an d The amount of cementingmaterial seen in these slices is less than was seen in sections of otherquartzite p ebbles (as mentioned above, variation in the amountof cement is characteristic of these rocks), an d there is a closerapp roach to . a quartz - mosaic structure , but in other respects all theusual features are exhibited . On e p oint, however, is worthy ofmention . In addition to the flin t- pebbles

,ro lled quartz - pebbles

were also present . These ranged in size up to about in . in -

.diameter .Fortunately some were cut through in the slices, so that it wasp ossible to determine by mi croscop ic examination that they werequartz - pebbles and not altered flint . The point is of interest sincethe recorded instances of the occurrence of quartz - pebbles in theReading Beds are few . Mr . H. J . Osborne White has stated thatthe occurrence of these p ebbles at the base of the Reading Bedsis by n o means rare

,but they ap p ear to have been recorded only

from Long Valley Wood , near Rickmansworth, Lane En d, NettlebedHill , and near Chalfont St . Giles .

1

The above evidence defin itely fixes the age of this quartzitep ebble (an d p resumably the others) as post—Cretaceous and noty ounger than the Oldhaven (B lackheath) Beds . The pebble presentsthe typical flattened ovoid shap e and is particul arly well rolled .

As is well known,the rounding of the pebbles in the B lackheath

Pebble Beds is of a very thorough character— in the typical exp osuresa subangular flint is unknown . The character of the beds suggeststhat their dep osition occup ied no great length of time —the timerequired for the rolling of the pebbles was p robably great in com

parison . That is to say ,the rolling of the pebbles probably

p receded their dep osition as the Blackheath Pebble Beds . A

well - marked p lane of erosion separates the Pebble Beds from the

underly ing Woolwich and Reading Beds, an d se ctions showingscoops where the Pebble Beds are seen to rest on low membersof theWoolwich an d Reading Series or sometimes to out completelythrough them and rest on the Thanet Sand, are of commonoccurrence . It would app ear that during this p re - Oldhaven

erosion of the Woolwich and Reading Beds, large numbers of flin tsan d occasional sarsen - stones were removed from them,

subj ectedto a great amount of rolling , under conditions which did not, as a

11 116 , permit of the decomp osition of the p ebbles, whereby therounding of the latter was p erfected, a nd that finally the pebbles

1 Proc. Geol . Assoc . , vo l . x x i, 1909—10 , p . 245 (with further references) .

70 H . A . Baker— Quartztte P ebbles of the Oldhaven Beds .

were deposited,in n o great length of time, to form the B lackheath

Pebble Beds .

From this “point of View we may regard the occurrence of theserolled quartzite - pebbles in the Blackheath Beds as additionalevidence of the pre - Oldhaven e rosibn o f the Woolwich an d ReadingBeds .

It is somewhat singular that Prestwich , in the classical series ofpapers on the strata between “ the London Clay and the Chalk,app ears never to have suggested the possibility of these quartzitep ebbles of the p ebble beds being rolled f ragments of sarsen - stone .He knew of their occurrence in the p ebble - beds, for he stated thathe had

.occasionally found them in situ, and suggested that the

similar p ebbles of the Westleton Beds may have been derived fromthe Lower London Tertiaries . He p ointed out their differencefrom the quartzites of the Triassic conglomerates, but suggestedthe p ossibility of their having been derived from the Palaeozoicquartzites of the Ardennes . The p oint is the more remarkableinasm'uch as Prestwich , in amassing strong evidence in favour of theWoolwich and Reading Beds having been o n e (an d possibly thechief) source of supply of the sarsen s an d puddingstones, was at

pains to emphasize the fact that the pebble beds overly ing theWoolwich and Reading Series rest up on a strongly eroded surfaceof the latter beds, an d are themselves derived in great part from thedestruction of the lower beds .

Summarizing , in conclusion, the main p oints put forward in thep resent communication, the, writer contends that without attemptingto dogmatize upon the question of the scop e and applicability ofthe term sarsen but emp loy ing it in the general sense nowp ermitted by usage, as free from the limitations some would imp ose ,the following p oints may now be regarded as established(1 ) The sarsen - stones an d puddingstones considered h ere are

cemented portions of sandy an d p ebbly Lower Eocene strata .

(2) The Woolwich “

and'

Readin g Beds have afforded one sourceof supp ly of these stones .

(3) The p ebbles , of “quartzite an d siliceous flin t- conglomerateo ccurring in the Oldhaven (B lackheath) Beds are rolled fragmentsof sarsen an d puddingstone derived from theWoolwich an d ReadingBeds .

EXPLANATION OF PLATE I .

FIG . 1 .— Rolled quartzite p ebble from the Oldhaven (Blackheath) Pebble Beds .

Road cutting east of Plumstead Common. Four - seven ths full size. The

quartzite con tain s rolled pebbles an d broken fragmen ts o f black flin t . Noteflint p ebble e in . lon g'

showing o n surface of quartzite at left - hand en d of

photograph . The quartzite also con tain s rolled p ebbles o f wh1te quartz .FIG . 2.

-Section o f p ebble , shown in Fig . 1 , showing flint. Ordinary light.Magn ified six diameters .

FIG . 3.—Section o f p ebble shown in Fig . 1 , showing flin t quartz - grain s rather

closely p acked, n ot much cemen t . Crossed nicols. Magn ified eighteendiame ters.

MAG . 1 920 .PLATE I .

p hoto et p hotomtcro

QUARTZ ITE PEI BLES or THE OLDHAVEN BEDS .

[To face p a g e 70

H. Bury— The C’hin es an d Ol ifis of Bourn emouth.

‘

71

The Chin e s an d Cliffs.

o f Bo urn em o uth.

By HENRY BURY, FGHS

I . THE CHINEs .

HE country round Bournemouth consists of a wedge - shapedp lateau, ly ing between the River Stour an d the sea,

. an d

ranging roughly from 100 to 200 feet above sea - level . Of thenumerous valleys wh ich intersect it, those that j oin the Stourpresent as a rule no special features

,but most of those running

down to the sea are of exceptional character an d are known as

chines—a term which does not admit o f very accurate definition,but is generally applied only to . valley s of more than usualsteepness .

It is somewhat remarkable that,although the Geological Survey

has published two editions of itsmemoir on Bournemouth,

‘ in neitherof them is an y attempt made to deal with either the form or theo rigin of these chines . Several o ther writers, however, have noticedthem,

an d have made suggestions as to their origin ; Ly ell,2 forexamp le , thought that they originated as

“the result of landslip s,though he does n ot attemp t an y details of _

the process or explainhow the country was drained before they arose . Mr . StarkieGardner3 considered them as simp ly enlargements of the innumerablefurrows cut by the rain in the cliff—face, and even speaks of newchines being formed in the course of a fewdays ; while Dr. Ord

4

takes p racticall y the same view, for after d escribing in detail theformation of these cliff - furrows, he adds : “ These illustrate thefirst step in the fo rmation of o ur chin es .

”

It is clear, then, thatwhile these three authors differ somewhat in detail they are all.

agreed in regardin g these valley s as having started in comparativelyrecent times in the face of the cliff

,an d having lengthened themselves

by growing rap idly inland . But although a few of the mino r indentations of the cliffs may possibly have been formed in this way ,y et with regard to all the principal chines— all

,at l east, that are

named as such in the 6 in . map of the Ordnance Survey— thereare strong reasons for doubting whether this hyp othesis is correct .In the first p lace, if the chines are actually growing longer, theirrate of growth must be greater than that of the recession of thecl iffs ; and since the latter is known to be in the neighbourhoodof a foot a y ear, the heads of the chines should exhibit signs of verygreat activity . Now a rough measure of such activity can beobtained ; first

,from the angle of slope, which is far less at

the heads of the chines than in the cliffs ; and secondly , from a

study of the vegetation . The face of the cliff is so steep and is

The Geo logy of the Coun try roun d Bourn emouth, l st edition, 1898 ; 2n dedi tion , 19 17.

2 Prin cip les of Geo logy , l 0th ed. , vo l . i , 1867, p . 533.

3 Quart. Journ . Geol. So c . , vo l . xxxv , 1879 , p . 220 .

4 The Natural History of Bourn emouth an d District, 19 14 , pp . 6 1 , 32 1 .

72 H . Bury— The Gh'

i n es an d Gl ijfs of Bourn emou th.

changing so rapidly that p lants have no chance of establishingthemselves on it, an d the same is true of the mouths of the chines

,where readjustment to the changing coastline is constantly goingon ; but the heads of all the p rincipal chines are (or were beforeman interfered) covered with rank vegetation an d afford no evidenceat al l of rap id erosion .

Secondly , the form of the chi nes must ‘be taken into consideration .

If we examine the valley of the Bourne (n ot usually accounted a

chine we find the sides rather steep ,but the bo ttom wide an d

fairly flat ; in fact, in section it has the form of a broad letter U .

In Durley Chine, on the other hand, the sides are exceedinglysteep an d the bottom narrow, so that a section takes the form ofa V . Passing next to. Branksome Chine (or Branksome Glen 1

)we find both these forms rep resen ted, the upp er p ortion of the val ley(i . e . that furthest inland) _being wholly of the U typ e, while thelower (from just above All Saints Church down to the sea) hasa V - shap -

cd‘ ravine carved in the floor of the U '

Clearly ,then, we have two valleys of differen t ages, a newer an d steep er on e

FIG . 1 .

— Tran sverse section o f Bran ksome Ch in e .which alone contains water, and an older one which is more thantwice as wide an d as long , being traceable inland .almost as far as

Parkstone Station, where it is trun cated by the slop e leading downto Poole Harbour“; while at the other end, after forming a wellmarked terrace on each side of the newer valley , it ends somewhatabrup tly about 50 feet above sea - level . It is, in truth , a hangingvalley ,

but its relation to the cliff is obscured partly by alterationsdue to man

,an d p artly by the fact that it curves towards the east

at this p oint, an d was formerly continued for some distance in thatdirection almost p aral lel to the p resent 01111 . The latter i sexcep tionally low opp osite Branksome Tower Hotel 2 for this veryreason

,namely ,

that it is here a section of the old valley floor (valleygravel, though not shown on the geological map ,

can be seen capp ingit) , an d not, as elsewhere,

_

a section of the plateau (Fig . Thisdouble structure can be traced in all the p rincipal chines of Bourn emouth Bay , as well as in the Bun nies of Christchurch Bayf

1 The latter name is used by Mr. Starkie Gardn er, the former by the Ordn an ceSurvey , by which what used to be kn own as Branksome Chme 1s calledBran ksome Den e Chin e

2 Se e Mem . Geol . Sufv . , Bourn emouth, 2n d cd . , p . 23, fig . 5 .

3 Quart. Journ . Geol . So c. , vo l . xxvi , 1870 , p . 532 .

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74 H . Bury—The Chin es an d Gl ifis of Bourn emou th.

. But we have still to account for the difference in level betweenthe old and the n ew valleys . If this feature had been commonto all the valleys of the district we should have been justified inp ostulating a change in relative sea - level

,and p erhap s con nectin g

the old valleys with the well - known raised beaches, rather than withthe later period of the Coombe Rock

,when the sea had sunk some

what below its present level . But we have seen that the differencein l evel is confined to those valleys which run down to the sea ,

and a l ittle consideration will convince us that,though a change

in'

sea - level is not in itself imp robable, the mere encroachment ofthe . sea on the land is quite sufficient to p roduce the observedphenomena .

There are strong reasons for believing that in former times a

river (Solent River) ran across what is n ow Bournemouth Bay ,being cut off from the English Channel by a line of hills connectingthe Isles ofWight an d Purbeck °

an d although op inions differ as to theexact time at which its southern boundary was breached by the sea

,

y et the balance of evidence seems in favour of a fairly late date . l

Pl ate a u

FIG . 4 .

— Long itudin al section showing the relation o f the o ld an d n ew valle y sto the changing shore - lin e, A , So lent River . B , Floor of o ld valley .

C an d D , Succe ssive positions o f the cliff , with the floor o f the n ew valley(dotted lines) adjusted to them .

The lateral streams from the Bournemouth district woul d p robablymeet this river about one or two miles from the present coast, butthe destruction of the river by the sea an d the subsequent recessiono f the coastline have led to a shortening of their valleys an d con

sequent readjustment o i the thalweg to new gradients . Owing ,however, to the greatly reduced size of the streams, only a shortand narrow portion of the old floor was affected

,. thus giving riseto the chines

,as shown diagrammatically in Fig . 4 . The samefigure also explains how,

without an y change in sea - level,the

remnants of the old valley floor appear at higher and higher levelsin the cliffs as the latter recede .There is

,it is true, no direct evidence that the Solent River

survived to quite so late a date as is here suggested , but the widefloors of the old valley s must have required time for their formation,and app ear to me more consonant with a fixed outfall into a mainriver than with a shifting one into a constantly encroachi ng sea

and the conditions are such as to render a stationary coastlinehighly improbable . Moreover, while it seems certain that chines,1 Mem. Geol . Surv Bourn emouth, 2n d ed 19 17, p . 48 .

H. Bury— The Chi n es an d Ol if e of Bourn emouth.

‘

75

both here and in the Isle of Wight, 1 are due to the advance of thes ea, I see no evidence o f that advance in earlier structures .

The difference between the hypothesis supp orted by Ly ell and

others and that here advanced may be summed up as follows .

According to the former the chines origin ated in quite 1 ecen t timesas min iature torrents in the cliff - face

,and have since been growi ng

steadily longer an d less steep (longitudinally ) while in my view,a lthough the chines themselves (reserving this term for l the newervalleys) are recent, y et they are the remnants o f an

_

o ld drainagesystem which anteceded the cli ffs ; and since the growth at thehead is, if not absent, at an y rate less rap id than the advance ofthe sea,

they must each y ear be growing shorter,and will (unless

marine erosion is permanently checked by man ) ultimately disappearaltogether .

II . THE CLIFrs .

The suggestion (first advanced , I believe , by Mr . Carus Wilson)that there has been a general increase in the steepness of the Bournemouth cliffs in the last thirty or forty y ears, has been widely accep ted ,a n d coupling this belief with a tradition of a marshy tract of shore ,Dr . Ord

2 builds up an elaborate theory of an old sea - cliff left farinland at the time of‘ the raised beaches, and only recently reachedagain by the sea . But before we accept such a sp eculative vieww e must be absolutely sure of the facts on which it rests .

As there i s nothing to show that the marshy tract was any thin gm ore than an extension of the valley floor of the Bourne ,3 and as it

i n an y case admits of a simple exp lanation,4 it need not be furtherdiscussed ; but the alleged change in the angle of the cliffs meritscloser attention .

My own intimate v uain tan ce with the western part of the bay(from Alum Chine to Poole Harbour) goes back fifty y ears, an d restsfurther upon many conversations wi th one who had been familiarwith that coast for some ten or fifteen y ears before and 1 am quiteconfident that, at an y rate within the regi on named and the timespecified, the general angle of the cliffs has undergone no chan gewhatever . Moreover

,Ly ell , who visited this coast in 1830 , evidently

found erosion going on rap idly ,since

,aswe have seen;he attributes

the origin of the chines to falls of the cliffs . On the other hand ,the evidence in favour of change having occurred app ears to me

t o amount to nothing more than this, that at certain p o in ts the cliffswere formerly more easily scaled than now ,an d for this I think

,

l ocal causes can be found without p ostulating a wide st1 etch ofraised beach

,which is entirely unsup p orted by evidence .

We have seen that the chines are growing shorter,and from the

condition of a few of them (notably Little Durley Chine) we may

1 Quart. Journ . Geol . So c . , vo l . xxvi , “

1870, p . 54 1 .

2 Natura l History of Bourn emouth, p p . 234—5 .

3 Ly ell, o p . cit . , vo l . ii , p . 531 .

4 Mem . Geol . Surv . ,Bourn emouth, 2md cd . , p . 66 .

76 F. Barke , Whee lton Hi n d,an d A . Scott

safely infer that some of their lateral branches have already beenobliterated . But the n ormal angle of the head of a chine i s less thanthat of the cl iff

, and therefore there will come a time when all thatis left of the former is an indentation of the line of the cliff, somewhatless steep than the latter ; and if

,as happ ens in ,more than o n e

instance,the chine ran parallel with the cliff , this diminished steep

ness might extend for a considerable distance . This I believe tobe

' the true exp lanation of some at least of the observations ,on

which Dr . Ord and others have relied . but it is not improbable thatimmediately to the east of the p ier another cause may also havebeen at work .

The ordinary gradient of the beach i s great-er than that of sucha Valley as the Bourne

,an d even at low water it is rare fo rmore than

100 yards of shore to be exp osed . But it is evident from Ly ell ’saccount of the submerged forest that in 1830 a very different gradientobtained opposite the Bourne, for he describes it as situated 200 yardsfrom the mouth of that val ley an d as ly ing between the beach an d

a bar of sand about 200 yards off . Such a diminished gradi ent iseasily a ccounted for as the r esult of the resistance of the peat inwhich the forest grew to the action of the waves an d tides ; butthe effect of it would p robably be to form a sort of groin , whichmight (since the beach materials normally travel from west to east)afford a good deal of p rotection to the cliffs on the Boscombe sideof the Bourn e , and give them time to assume a very moderate slopecompared with other parts of the coast . For many y ears , however,the submerged forest has been seldom visible ,1 and - there has beer-in o such decreased gradient opp osite the Bourne . This“ has oncemore exposed the clifls to the full force of marine erosion ,

an d

i n this way we may p erhaps account not only for the chan ges 1n

gradient, but also for the alleged sp ecial activity of this erosionbetween Bournemouth an d Boscombe . 2

Quartz o se Co n glom e rate at Caldo n Low , Staffo rdshire .

By F . BARKE , F.CS . , WHEELTON HIND ,M.D .

,B .S.

,

an d A . SCOTT , M.A . , D .so .

IN the GEOLOGICAL MAGAZINE for February , 1919 , J . W. Jackso'n '

an d W. E . Alkins 3 described the occurrence of a quartzoseconglomerate at Caldon Low, Staffordshire . In August one of us(F . B . )

4 pointed out some p revious references to this outcrop .

The curious an d ambiguous rep ly by Messrs . Jackson an d Alkins1 The p eat does n ot seem to have been broken up , but to have sun k down ,

which goes far to sup port Ly ell’s con ten tion that in this p articular case thesubmergen ce of the forest is due more to un derminin g of the p eat than to an y

general chan ge in sea - level.2 Natura l History of Bourn emouth, p . 63.

GEOL . MAG . , Vo l . LVI , 19 19 , p . 59 .

Ibid .,p . 384 .

Ibid, p . 430 .

(w

h

o:

Quartzose Cong lomera te at Caldo n Low , Stafio rdshi r e . 77

to this letter necessitates a detailed an d accurate descrip tion of thehistory an d p resent condition of the exp osure . This rep ly was

particularly ungracious, since one of us in December,immedi ately after the reading of Mr . Jackson ’s first pap er at Man

chester on the subj ect, had communicated to him the fact that thisquartzose conglomerate had been known to local geologists for manyy ears , an d had been shown to the members of the Geologists’Association during the excursion to North Staffordshire in 1890 .

To settle finally the p osition of the quarry which we p rop ose todiscuss, an d which is .the same quarry as that described byJackson an d Alkins, its longitude is 1

°

53’

10” W. an d latitude

53°2’

20”

N ., _

an d the height is about 900 feet above O .D .

Previous History .

- In an address delivered in 1873, Wardle 1mentions the “existence of a sand an d clay dep osit at Caldon Low,

and this pit was first visited by two of us in 1889 . It was then inpart a sand an d clay -

p it of the type which is found in the WeaverHills

,with p ockets of sand and clay in the centre an d masses of

conglomerate at the edge . It was very briefly mentioned in thereport 2 of the visit of the Geologists ’ Association in 1890 , but n o

o n e could be blamed for not recognizing the spot described .

However, this was remedied by J . A . Howe in his pap er,3 ‘f

Noteso n the Po ckets of Sand an d Clay in the Limestone of Derbyshirean d Stafiordshire . In 1905 the North Staffordshire Railway Co .

began to extend their quarries no rthwards, an d, clearing away thesmall pocket of sand and clay , laid bare a basin - shaped mass o f

quartzose conglomerate in - which they drove a small siding in an

e astward direction . This fact was noted in the rep ort of theGeological Section of the North Staffordshire Field Club .

‘

Presen tCondition of Exp osure — At the p resent time the quartzosematerial is being rap idly quarried away ,

and on both north an d southfaces of the cutting the actual junction of the conglomerate withthe undisturbed an d well - bedded limestones

,which here form "

a

l ow anticlinal,the northern limb dipp ing north at an angle of

can be clearly seen . The contact which forms the western boundaryo f the conglomerate can be traced on both sides of the cuttin g fromthe top of the quarry faces to the floor, the angle of inclination beingvariable, but averaging about 50° to In the centre the bottomo f the deposit is not visible

,as it passes under the floor of the cutting .

Near the junction the quartzose material shows vertical beddinga nd is much more conglomeratic than towards the centre .At the eastern en d of the cutting the contact with normal lime

stone also rises qui ckly ,but not to the top of the face

,as a thin bed

o f conglomerate about 1 , foot thick, with a bed of crinoids above itand normal limestone below

,is seen to pass eastwards . On tracing

1 North Stafio rdshire Field Club Addresses, Pap ers, e tc . , 1875 , p . 34 .

2 Proc . Geol . Assoc . , vo l . xi, 1890, p . 130 .

3 Trans . North Staffordshire Field Club , vo l . xxxi , 1897, p . 143.

Ibid . , vo l . x] , 1906 , p . 85 vo l . 1111, 19 19 , p . 101 .

78 F. Bar lce, Wheelton Hi n d, a n d A . Scott

this bed , which , although fairly level , does n o t always maintainthe same stratigraphical horizo n , it suddenly rises to the top of thequarry by a vertical p ip e 2 or 3 feet in diameter . A little furthereast another p ip e of conglomerate comes down from the top an d

connects with another thin bed at a lower level than that a few yardsaway . As a whole, the field relations suggest that the conglomeratefills a subterranean hole 1n the limestone

,p robably formed by solution,the thin beds rep resenting several underground watercoursesleading into the main hollow . The questio n of a contemp orarydep osit of quartz conglomerate does n o t

,therefore

,arise

,an d there

is n o connexion with the quartz - pebbles in beds of D2 age at'

Castleton .

Diagrammatic sectio n (E . showin g the quartzo se con glomerate (do tted) atCaldon Low . Th e upp ermo st lin e repre sen ts the top an d the lowest linethe bo ttom o f pre sen t expo sure .

The occurrence o f fossils in the conglomerate is interesting .

The fauna at once strikes one as a D2 assemblage and quite di fferentfrom an d having nothing in common with the fauna of the Caldon J

Low Limestones . We consider that the fossils are all derived, “because

,first, the fauna of the conglomerate is amixed one secondly ,examination of thin sections shows a shattering of the fossils, many

of them being in a fragmentary condition ; thirdly , the typ ical “fine grained limestone of Caldon Low is found in angular blocksin the conglomerate . These blocks are very much larger than an yof the other detrital materials, and this, together with their unrolledcondition

,suggests that they have fallen from the sides or the roof

of the subterranean hollow . Mr . Howe mentions the fact thata block of Pen dleside shale , containing Posidon ie lla min or, was

found by one of us in the clay p it formerly on this site .The horizon of the Caldon Low Beds may be definitely assignedto the base of the Viséan . The fauna 1s a very limit-cd one an d exactlySimilar to the homotaxial equivalents of the Clitheroe an d Belgianp rovinces . Can in ia should occur near this horizon . Brachiopodsare limited to

_

Prorluctus numerosa-

a Chon etes p ap i lion acea21

form,an d Orthotetes aff . cren istria,

0 1 form . Corals are rep i esen ted

by a very small form of Syringop ora, gasterop oda by very largespecies of Nati cop sw Be llerop lzon cornuarieti s, an d other spe cies ofthis genus . A fragment of a large Myali n a 1s the only p elecyp odwhich has been obtained .

1 Lo c . c it . , p .

‘144 .

Quar tzo se Co n g lomerate a t Ca ldon Low, Stof or olshi r e .

On comp aring the above. with the list given by Messrs . Jacksonan d Alkins, it will be n oted that the fauna of the con glomerateis quite a different one, and is indicative of a much higher horizon .

Beete J'

ukes was eviden tly correct when , -in 1839,in a section across

North Staffordshire in his pap er Sketch of the Geology of Derbyshire

,

” 1 he shows the beds at the base of Caldon Low to be fairlylow down in the series .

Petrograph-

y of the - Cong lomerate .

— The p ebbles in the con

glomerate vary greatly in - size an d in number, and comprise manyrock typ es . The largest are the angular and subangular blocks of

grey Caldon Low limestone , while smaller but rounded fragmentsof the same material are common . In general the material of finergrain is decidedly water rolled . So far as distribution 1s concerned,the marginal p ortions of the conglomerate are much less rich inp ebbles

c

than the interior,but even in the latter the p roportion

of visible detrital material varies from p lace to p lace . In additionto the rock containing large limestone fragments, several distincttyp es of conglomerate can be distinguished ,

first,a rock con taining

numerous p ebbl es, l

up to an inch orC

t o in diameter, with relativelylittle matrix secondly ,

a similar but more fin e—grained rock and

thirdly , a very fin e -

grained limestone,with abundant minute

fragments of quartzose material . The p ebbles include fragmentsof grey Caldon Low limestone

,fossiliferous limestone , several

types of quartz rocks, cherts, shales , Lydian s tone,an d some altered

igneous material .Several sp ecimens of the conglomerate an d the normal Caldon

l i-meston es have been sectioned an d examined microscop icallyThe ordinary Caldon Low limestone shows no trace of quartzosematerial

,an d is comp osed mainly of organic remains

,includingbrachiopod shel ls

,crinoid stems

,fragments of corals , tests o f

'

foraminifera, etc . in a matrix which i s apparently structureless,

an d was p robably a calcareous mud originally . Crystalline calcite ,ap art from veins an d j oints

,is consp icuously absent . - The larger

fragmen ts'

o f limestone in the conglomerate are very similar .The coarse quartzose conglomerate consists of several typ es ofrocks and organic fragments cemented together by relatively largecrystals of calcite . The shells an d other calcareous materials are

obviously fragmental, and the _lack of in ternal structure an d. op ticalhomogeneity of many fragments suggest _that recrystallization hasoccurred .

“

Often the calcite '

o f the matrix has crystallized roundal limestone in such a way as to be optically continuousPieces of dolomitized material an d oolitic grams can also

be"

seen .

Several typ es of quartz - rock are presen t . Vein - quartz occurscommonly ,

each p iece being optically homogen eous except for thep resence of strain shadows

,which are sometimes so p rominent

and so orientated as to indicate that the material has undergone1 An a lyst, vo l . ix , 1839 , p . 2 .

8 0 F. Barke, Whee lton Hi n d, an d A . Scott

considerable p ressure . This effect is very similar to the one common ly observed in Bunter p ebbles . In one “

sp ecimen of the conglomerate the detrital material is mainly vein - quartz

,an d practically

e very p ebble shows decided traces of the efi'

ect of p ressure . The

o ccurrence of this rock, with such a large p rop ortion of vein - quartz,interesting , “ as bands of similar material can be observed in some

of the sand an d clay -

p its near Friden , Derbyshire .In many sp ecimens the p ieces of vein - quartz

,although or1g1n ally

o f a roun ded form have invariably a marginal . development ofs econdary quartz in op tical continuity with the original .grain ,an d p ossessing p erfect external cry stal forms . The latter are so

sharply defined as to make it p ractically certain that the secondaryg rowth has occurred in s itu,

as even slight rolling would have reducedt o some extent the p erfection of the faces . The p resence of secondarygrowths on quartz has been noticed by Howe in the material fromthe Bibden Pit .

A p ebble of equigranular quartzite, with relatively large interlocking quartz crystals an d little visible cementing material,has

a decidedly metamorphic asp ect, an d is p robably derived frompre

- Cambrian or early Palaeozoic dep osits . Several typ es of sands tone which closely resemble some of the Carboniferous rocks ofthe Midlands are also p resent . A fin e -

grained sandstone, which ismade up of subangular grains of quartz with subordinate felsparin a siliceous matrix ‘

of quartz and colourless mica,is very like some

of ‘ the local rocks of Millstone Grit age , which have been used forrefractory purposes, while other rocks, which can also be matchedamong the local depo sits of the same age , included a coarse sand ?s tone with rounded quartz cry stals an d scarce felspar in a cementof secondary quartz, an d a fin e—grained sili ceous conglomerate ,consisting of fragments of rounded vein - quartz

,quartzite, sand

s tone,an d shale in a matrix of secondary quartz and mica . These

rocks resemble closely the so - called ganisters of the StocktonBrook district .Another rock which has angular to subangular quartz grainswith little —or no felspar, set in a mosaic of interlocking crystals

o f very fine secondary quartz , closely resembles some of the crows tones of the Pendleside Series which occur in the neighbourhoodo f Congleton . Other equigranular rocks, consistin g almost entirelyof quartz,With wavy extinction, an d thin interstitial lay ers of cement,are suggestive of the ganisters of the Lower Coal - measures .

Several fragments referable to . chert can also be recognized ,an d others of very fine grain app ear to be indurated quartzoseshales , The igneous rocks include tuffs , etc . , as well as - felsiteswith a decidedly aphanitic texture .With regard to the pro portio n s . o f the v arious rock - typ es, the

fragments of quartz rock far exceed the others in amount, an d ofthese the sandstones and crowsto n es p rep onderate over the

1 Lo c. cit . , p .

‘

146 .

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82 Quar tzose Con g lomerate at Ca lolon Low, Stafiordshi r e .

Bunter beds, an d in the other the limestone from the roof ofCaldon Low limestone .The lithological examination of the materials of the Caldon Lowcong lomerate and the sand an d clay—p its of the Weaver Hills an dDerbyshire has shown that they are all essentially the same . The

deposits in each case were p robably laid down by river action,

the consolidated nature of the Caldon Low material being due to thefact that the hollow in this case was a subterranean one

,dissolved out

of the limestone, which would p rovide the calcium carbonate whichforms the cement . So far as the origin of the pebbles 1s concerned,these include many typ es of Carboniferous rocks, an d, as a whole,are a typ ical Bunter assemblage ; hence it seems feasible to inferthat they are derived from dep osits of the latter age .

Con clus io n s — The quartzose con glomerate at Caldon Low is n ot

a p en eoo n temp o ran eous bed dep osited unconformably on the

Caldon Low limestone , but 1s an in fillin g of a subterranean hollowand several underground watercourses in the limeston e .The p ebbles are derived mainly from Bunter dep osits, and havereached their present lo cation at some p eriod between Bunter an dGlacial times .

The fossils in the conglomerate are all derived an d mainly o f

D2 age .

REVIEWS.

Fo ssi L PLANTS : A TEXT - BOOK FOR. STUDENTS OF BOTANY_

AND

GEOLOGY . By A . C. SEWARD . Vol . IV : Ginkgoales, Coniferales ,Gnetales . pp . xvi 544 .

1190 illustrations . CambridgeUniversity Press . £1 18 .

THE fourth volume , dealing with the remaining portion of theGymnosperms

,brings to a conclusion this imp ortant work ,

of which the first part appeared in 1898 ..The main bulk of the plant

remains of the past has now been dealt with , but the treatmentof fossil Angiosperms has been left for future writers

,as the author

realizes that a reliable summary of our p resent knowledge of thegeological history of the flowering p lants woul d involve an immenseamount of labour, and the co - op eration of exp erts in systematicbotany . He considers that he is not adequately equipped for thistask, and it would seem probable that it will be long befo re any oneis found to undertake it

,unless one of the American palaeobo tan‘ ists

step s into the breach .

The whole work has covered the wide and scattered field ofpalaeobotany in a remarkably thorough way ,

an d almost all theimportant fossil genera have been mentioned or described , both asregards those based on structural material an d those formed forimp ressions . Brief but excellent summaries of the modern - plantsto which the fossil types are related have been given, an d these havebeen of considerable utility in giving a conception of the natureof the plants which may be rep resented as fo ssils

'

by a group ofincomp lete fragments ; they also assist in the exp lanation of thesystem of classification emp loy ed an d indicate what features are ofsp ecial importance .In the volume just published a full account of the fossil Ginkgos

is given . This is of esp ecial interest to the geologist on account ofthe widespread occurrence of this group in Mesozoic times , as wellas owing to the solitary survivor found to - day in the Maidenhairtree . It is characteristic of the caution exhibited throughout thework with regard to the multip lication of sp ecies, that the first of the190 illustrations in this volume dep icts the varied forms whichthe leaves of the modern Ginkgo bi loba may assume . “

Some palaeobotanists consider that Professor Seward is too conservative withregard to species, but it is certainly p referable in a work of thischaracter to keep genera an d sp ecies united until good groundscan be produced for their separation . For example , in the case ofa fossil which is very common on the Yorkshire coast an d

which Often resembles a group of Pine needles, the genusCzekan owskia is defined so as to includ e forms with entire and

bifurcated leaves, on account of their simi larity-

in arrangementon short shoots an d also because of the close identity of theirep idermal structure . Some palaeobotanists would separate theforms with entire undivided leaves into the genus So len ites, but

84 Revi ews— Fo ssi l P lan ts .

though this course has not been followed , the view is mentionedan d references are given which will enable the student who isinterested to" investigate the matter for himself .Several Palaeozoic genera,

such as Psygmophyllum,which have

been assigned by various authors to the Ginkgoales are described,but it i s pointed out that the evidence on which this classificatio ri

is based is wholly inadequate .A considerable section] of the book is devoted .to the considerationof fossil coniferous woods , a subj ect which badly needed summarizingin a broad comp rehensive way ,

and which has also been dealt withby

‘

Krause l in a current number o f_

Paloeon tograpkica . The maj orityof the pre - Tertiary p etrified woods are of Coniferous affinities ; theyare by no means uncommon , but their identification has p resentedmany difficulties 1n connexion with the characters to be used an din their nomenclature . Several p revious -authors have dealt withgroup s of woods of a particular age or from a p articular region ,but a recent comp rehensive summary was lacking . The p resentdescrip tions and classification ought to be of great assistance tothose who wish to determine fossil woods, without making a Sp ecialstudy of the recent and fossil forms an d reading through thee xtensive literature on the subj ect .

The study of fossil coniferous twigs an d Of the remains of coneshas also been greatly assisted by the succeeding chapters . Someforms

,such as those from the American Cretaceous had been

thoroughly investigated, but a vast mass of unsystematized informa

tion existed in botanical and geological literature about other typ es .

The student is invariably puzzled to find Permian twigs describedas Walchia ,

while apparently similar typ es from the Trias‘

are knownas Vo ltzia

'

an d from the Jurassic as Payiop kyllum or Elatides . Thesummaries of the characters Of - the twigs an d cone structures up onwhich these generic distinctions are founded

,will be a g reat help toboth students an d investigators, an d should assist in standardizing

our nomenclature . The examination an d criticism of all the evidenceby an author who is an enthusiastic student of the recent Coniferaemeans a considerable step forward in ourknowledge of fossil p lantsand of the p ast history of the cone - bearing trees .

The title o f '

studen t has just been app lied to the author of thismonumental Work, and it is to students in the widest sense of theword that this textbook will app eal . Parts of it will be of greatvalue to the e lementary student who i s making a first acquaintancewith the p rincipal fossil typ es, but as a Whole the work will beinvaluable to all who are engaged in a study of the vegetation ofp ast ages . The very cop ious references to original pap ers, todiscussions, and to the best figures will be of immense help to all

who are iriterested in this great field of knowledge . The list ofworks referred to in vols . iii and iv which IS p rinted at the closeof vol . iv . occup ies fifty - one pages , an d indicates the extent of thel iteraturewhich has been used m the comp ilation of this book . There

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86 Revi ews— Crysta l liza ti on—Bifi

fer en tiati on .

With durain the insoluble residue is larger an d coarser and the

solution lighter, while fusain is hardly dissolved at all,and a largefibrous residue is obtained .

In thin sections,also

,a graduating change of app earances is

noticed fusain generally is comp osed of a mass of black and opaquewoody tissue with thickened cell walls and emp ty cell lumina .

Durain consists of a “black,opaque , granular groundmass enclosingy ellow Spore coats . Clarain is clear, coloured red an d y ellow ,

an d

abounds with p lant structures of all kinds , while vitrain. is alsoy ellow and translucent

,but without any trace of organic structure .The pap er is illustrated by two p lates, one in colours, Showing

very clearly the difference in the thin sections of the four subdivisions, and in the so lutions obtained from them, an d also bya text - figure in which their distribution in typ ical sect ions of coalis shown by conventional stippling .

W. H. W.

CRYSTALLIZATION—DIFFERENTIATION IN IGNEOUS MAGMAS . ByN. L . BOWEN . Journ al of Geo logy, vol . xxvii, 19 19 , pp . 393

430 .

EADEBS of Anatole France ’s La Rotisserie ale la Rein e Pédauquewill remember that M . d’

Astarac,having once conceived the

notion that sy lphs and salamanders have a p resent—day existence ,found no difficul ty in explaining quite ordinary happ enings in thelight of his extraordinary concep tion . Similarly ,

though happily hisnotion rests on foundations more secure than did M . d

’

Astarac’

s,

Dr. Bowen has no difficulty in exp laining all p etrologi cal happ en ingsin the light of his cry stallization—differentiation concep tion . In

both cases on e can observe the same wholehearted devotion toa charming concep tion, but also the same neglect of the moreobvious deductions .

Dr. Bowen criticizes Daly ’

s views on syntexis and maintains thatassimilation p lays but a minor part in differentiation, for , eventhough comp lete aby ssal assimilation be admitted, the p roblem ofthe sp litting of the resultant syntectic magma is still one ofSeparation of phases . He also combats the limestone syntectichyp othesis of the origin of the alkaline rocks .

In dealing wi th liquid immiscibility in differentiation, Dr . Bowenconsiders that this factor is of no importance whatever . He

deduces that a . blotchy or patchy separation of phases must followfrom liqui d immi scibility , and from the general absence of thispatchiness in natural Igneous rocks he concludes that this factor 1 sn ot op erative . In opp ositi on to this conclusion one must point outthat the common occurrence of patchy differentiation in quartzdolerite Sills in Scotland has led to the view that liquid immiscibilitymay sometimes be a most important factor (Glasgow Memoir, p . 148)

Revi ews— Crysta l l i za ti on—Difier en tiati on . 87

Again , Dr. Bowen con siders that abrup t transition would not beexpected on the immiscibility theory ,

since an emulsion would result .Where immiscibilityhas been claimed inMull as yieldingdifferentiatesin p lace p erfect transitions occur (Summary of Progress for 1913,pp . 48, 49 , Of course, transition may be exp ected on an ytheory of gravitational differentiation .

Using the Duluth lop olith as an example , Dr . Bowen discusses thegabbro -

granophy re association an d claims that this discontinuousvariation can be exp lained by the mechanical straining Off of themother liquor (granophyre) from the already solidified crystals(gabbro ) under the influence of pressure . This mechanism is , o f

course,well known in Britain

,though its advocacy by Mr . George

Barrow nearly thirty y ears ago in relation to certain intrusions inthe East Highlands (GEOL . MAG .,1892, p . 64, and Quart . Journ .

Geo l . So c .,1893

, p .

Dr . Bowen’s suggestion (p . 417) that banding of gabbros an d

peridotites is not a_

form of flow- structure will scarcely receivecredence . Here the likeness of Dr . Bowen to M d

’

Astarac becomesesp ecially close . He believes that banding is a reaction to

mechanical stress on a crystal mesh with still fluid matrix , an d thatthe stress tends to give rise to cavities into which the‘matrix exudes ,while the crystal mesh above and below packs . On e can scarcelydoubt that such an origin would Show itself in an o rientation of theearly minerals with their axes perpendicular to the exudation bandswhich they border . On e has only to look on a large surface of abanded rock— esp ecially of a porphyritic banded rock— to perceivethat the mechanism evoked by Bowen has n ot op erated , but thattrue flow has occurred . Moreover

,Dr . Bowen’s exp lanation , on his

own theory , would app ly only to an ultrabasic rock banded withmore acid rock and n ot to the very common case in which gabbros ,for instance, are banded with scarcer ultrabasic lay ers .

Dr . Bowen discusses the origin of nodules an d schlieren in igneousrocks, and considers them to be due .to crystal jams resultant fromthe packing together of cry stals at constricted p oints and theirsubsequent removal and partial resorp tion in the main body ofthe magma . Such filter p resses, required here an d elsewhere byDr . Bowen,have been found to be quite unworkable when copiedin industrial p rocesses .

This pap ermust be welcomed chiefly because it will rouse claimantsof liquid immiscibility to renewed exertions . There is little , if an y ,

tendency on this side of the water to rule out either settling of crystals(postulated seventy y ears ago by Darwin) or mechanical straining(p ostulated thirty y ears ago by Barrow) as factors in differentiation ,but there is a tendency , p erhaps a growing one, amongst fie ldworkers to supp ort the claim that liquid immiscibility is a cera causa

in addition . Field observati ons will supply , one believes, the key todifferentiation .

H. H. READ .

88 Revi ews— Pa laeozo i c Worms an d Hydr o ids .

PALE OZOIC WORMS AND HYDROIDS IN VICTORIA .

CHAPMAN (1919 , Proc .

'

Boy . Soc . Victoria ,vol . xxx i

, pp . 315

24, p ls . xiii, xiv) claims to have found the gill - plumes ofthe Silurian worm Trachyderma, well preserved in the Me lbourn Ian

Mudstones near Keilor, Victoria . This evidence confirms the usualreference of the fossil to the Chaetop oda,

an d suggests that it belongsto the Sabe lliformia . Mr . Chapman regards Eotrophon ia setigera

E. O . Ulrich, 1879 , as similar gill p lumes . This came from theLower Cincinnatian beds of Covington, Kentucky ,

not fromCincinnati itself . Mr . Chapman also describes a new Cornulites(C. youngi ) from Lower Ordovician slates with Didymograp tuscaduceus

,on the Moorabool River north - west of Geelong , an d claims

it as the oldest recorded . On the evidence of a flattened basalattachment

,Mr . Chapman believes that this genus as well as

Pteroconus Hinde (=Nereitop sis Green) is a tubicolar Chaetopod .

In another pap er (tom . cit . , pp . 388—93, p ls . xix,xx) Mr . Chapman

refers some finely p reserved sp ecimens from the Lower PalaeozoicLan cefie ld slates to the Hydroid Order Calyp toblastea , , underthe names Archaeo lafoe’a n .g . an d Archaeocryp to laria n .g . He alsorefers to the same Order the Ckaun agrap tus an d Mastigograp tus

o f Ruedeman n ,an d describes a new sp ecies of the latter as M . mon e

gettce . (See Plate XV in GEOLOGICAL MAGAZINE , December,The discovery is an interesting one, for, with doubtfulexcep tions in the Pleistocene, the only fossils hitherto assignedto this Order are the Dendrograp tidm. Until rep resentatives havebeen found . in the intermediate strata,_

scep tics will doubt thelineal descent of modern Sertularians an d their allies from theseancient forms, however great the external resemblance may be .

A STUDY OF _THE BRACHIOPOD GENUS Pz Arifs rB oPfl rA . By

EULA DAVIS MCEWAN . Proc . US . National Mus ,vol . lvi,

1919, pp . 383—448

, p ls . 48 —52 .

THIS is a study of the North American sp ecies of the well - knownOrdovician and Silurian genus Platystropkia, leading to a

systematic arrangement based on their supp osed evolutionaryhistory . We say-well known

,but

,as Miss (or Mrs . ) McEwanpo ints out

,the determination of the genotyp e Terebratulites

biforatus Schlotheim is still uncertain . She therefore selectsas a new genotyp e Platystrop kia laticosta Meek, 1873. This actionis surely ill - advised, even if admissible . Two alternative coursesare op en to a reviser . First to attemp t the fixation of the genotype .Schlotheim

’

s description, unaccompanied as it is by a figure, may be

unintelligible to a modern palaeontologist, but this may Only bebecause of his larger acquaintance with alli‘ed forms and his moreminute discrimination . Von Buch

,we are told

,saw the holotyp ein the Berlin Museum, and had no difficulty in p ointing out the

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9 0 Revi ews— Blo ckMou n ta i n s i n Northern Nelson .

latent possibilities transmitted to the various groups and sub

g roup s, and expressed ,

in a defin ite order whenever the appropriatee nvironmental stimulation was present This defin ite order inthe succession of the morphic stages is represented in a table Underthe heading Orthogenesis ”

,but why this somewhat metaphysical

t erm should be used Is not apparent, for it is not easy to see howthe order could have been an y other . Another table shows how wellthe classification agrees with the known stratigraphical distribution ,e xcep t as regards the Ponderosa group .

We hOp e that Miss McEwan will continue her studies, an d thatshe will have the opp ortunity of extending them to Europ eanmaterial . F . A . B .

BLOCK MOUNTAINS AND A FOSSIL DENUDATION PLA IN IN NORTHERN

NELSON . By C. A . COTTON ,D .Sc .

,Victoria University College ,

Wellington . Trans . New Zealand Inst ,vol . xlviii , 19 15 ,

pp . 59—75 .

HIS pap er was written p rior to Block Mountains in New

Zealand (by the same author) , in which the subj ect of blockmountains is treated more fully .

The district examined here is a very small one,the writer con

fining his attention to the Aorere—Gouland Dep ression an d the

Go uland Downs Depression but the theories advanced serveas a working hyp othesis which gives much assistan ce in the interpretation of this particular district . It would appear that therelief which the deformed undermass p resumably had in some earli er

.p eriod had been almost entirely destroyed p rior to the d epositiono f the coverin g strata . After the period of dep osition of the coveringstrata, there occurred strong differential movements which sketchedo ut the bread outlines of the land forms of the p resent day ,

led tothe formation of many consequent rivers, an d inaugurated the

cycle of erosion in which the maj ority o f the details of the surfacewere develop ed . This is quite a departure from the interp retationgiven by Bell in his Parapara bulletin , in which he supposes thatmaturely dissected mountains occup ied the area in the periodimmedi ately p receding that in which the covering strata were laiddown, and the p eriod of dep osition was one of only partial submergence .PRELIMINARY REPORT ON THE ECONOMIC GEOLOGY OF HAZELTON

DISTRICT,B .C

'

. By J . J . O’

NEILL . Department of Mines,Geological Survey of Canada, Memoir 110 . 1919 .

HIS rep ort, though short, is somewhat diffuse . It deals with “

the

mines of an area of 225 square miles, situated 130 miles northe ast o i Prince Rup ert . The region is described as consisting of foldedUpp er Jurassic sediments with interbedded tuffs and tuffagglomerates, invaded by batholiths of granodiorite an d smallbatholiths an d dykes of granodiorite - porphyry

Revi ews— A ids fln Practica l Geo logy . 9 1

The ore dep osits are genetically connected with the igneous rocksan d occur in veins which are later than the dykes . The lode stuficonsists o f brecciated material showing two p eriods Ofmovement andmineralization . The structure of the ores indicates that the earliermineralization led to the introduction of large amounts of chalcopyrite, with small quantities of gold an d molybdenite . Parto f the chalcopyrite has rep laced secondary actinolite

, giving risie

to the name hornblende ore The later minerals are zincblende, tetrahedrite, argentiferous galena, chalcopy rite (in smallquantities) , with banded quartz an d some carbonates .

The relation of the veins to the granodiorite app ears to have adirect bearing on the mineral paragenesis . Thus, those veins whicho ccur within the boundaries of the larger igneous masses are

characterized by the additional presence of magnetite an d haematite ,and those near the contact by pyrrhotite an d arsenopy rite . Magnet ite is stated to have preceded the pyrrhotite , as it has been partlyrep laced by it . Tourmaline also occurs, rarely . A p oint of interesthere brought out is the relation of the two group s of ores, indicatinga phase - sequence ofmi neralizations, separated by an interval of time ,during the last stages of consolidation of the igneous rock . Therep ort is illustrated by excellent microphotographs of polishedsp ecimens of o res .

AIDS IN PRACTICAL GEOLOGY . By Professor GRENVILLE A . J .

COLE'

, Seventh edition . pp . xvi + 431 ,with coloured frontispiece

,2 p lates, an d 136 figures . London

Charles Griffin CO .,Ltd . 1918 . Price 103. 6d.

HIS book was first published nineteen y ears ago ,an d it is

sufficient testimony to its usefulness that it has now reacheda seventh edition . The author has made few changes in the p resentissue, which does not differ greatly from the third edition n everthe

l ess, the work is well up- to - date,an d such alterations as seemed

desirable have been carried out . It is not intended to take the placeo f an ordinary textbook of geology , but rather to supp ly an aid tothe student working in the field, help ing him to interp ret what heObserves an d to determine the character of the sp ecimens he collects ,whether they be minerals, rocks, or fossils . It is imp ossible fora field -

geologist to carry his interest very far and to apply hisknowledge very closely without some acquaintance with the commontypes of fossils and Of their chronological an d evolutionarys ignificance, and the author has done wisely to include an illustrateda ccount of the more imp ortant group s of fossil invertebrates . We

venture to hope that in a future edition , which should soon bereached, he may add some descrip tion Of the commoner vertebrateremains, especially such as are found in this country . The workis very approp riately dedicated to the memory of the lateProfessor Judd .

F . H. A . M .

9 2 Revi ews— Tu n gsten an ol Ti n i n Burma .

THE DISTRIBUTION OF ORES o r TUNGSTEN AND TIN IN BURMA .

By J: COGGIN BROWN and A . M . HERON . Rec . Geol . Surv .

l n dia,vol“ 1, pt . ii, pp . 101—21 , with two plates (maps) .

1919 .

IN this pap er we have at last definite detailed information as to

the geological occurrence an d relationship s Of the tungsten andtin lodes Of .Burma and ' the neighbouring districts . They extendover an area 720 miles in length, from By ingy i in the Yamethindistrict, Southern Shan States, to Maliwun in Mergui , in the extremesouth . The lodes are closely associated wi th a very acid graniteintruded into the ancient Mergui sediments . Some - Of the lodes aretyp ical pegmatites and greisens, while others are quartz veins inthe n arrower s en se of the term,

but all app ear to be of Similarmagmatic origin . This is

_

supp orted by the occurrence in p laces Of

tourmaline,topaz, and fluorite . The characteristic mi nerals .

are arsenopy rite, chalcopyrite, py rite, molybdenite, native bismuth ,an d o ther bismuth ores .

_

At the p resent time a large p roportionOf the output of both wolfram an d cassiterite

"con cen trates comes.

from various detrital dep osits . Wolfram is rare in true alluvium,

but cassiterite is common in places .

Full descrip tions are given of the lodes in all the mines, most ofwhi ch have been insp ected by the authors . Hermy ingy i is probablyat

_

the present time the largest wolfram mine in the world, having “

p roduced in 1917 no less than tons of concentrates, out of"a total of tons for the whole district .

REPORT ON A COLLECTION OF CAINOZOIC FOSSILS FROM THE:

.OIL - FIELDS OF PAPUA . By F . CHAPMAN . WITH GEOLOGICAL .

INTRODUCTION by ARTHURWADE . Bul letin of the Territory o fPapua, No . 5 . 18 pp . Melbourne

, 19 18 .

THE Oil - bearing strata of Papua skirt the coast on the southwest from Yule Island to the Parari delta . They range , as .

appears from Mr . Chapman’s determinations,from Recent to the

base of the Miocene,an d below them are some grits, conglomerates,

an d sandstones, apparently without fossils but with traces Of

limestone and coal . Mr . Chapman’s report is for the p resent onlya list, but as Dr . Wade p oints out in a most interesting introduction ,it is of much imp ortance in working out the classification an d

tectonics of the strata an d in elucidating such wider questions as,

the relation Of Papua to the adjacent land areas .

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94 Corr esp on den cefl T. Fran kli n Sibly .

place, unless it be in Central Mullf—is familiar to every studentof our Tertiary igneous rocks . Whatever be its significance, itdisp oses effectually of Mr . Craig ’s argument .If

, without discourtesy ,I may p lay the mentor in my turn , Iwould hint in conclusion that a little knowledge, when j oined to

a large measure of assurance, is a dangerous thingALFRED HARKER .

ST . JOHN’

S COLLEGE , CAMBRIDGE .

Jan n ary 1 2 , 1 920 .

HZEMATITE IN SOUTH WALES .

SIR,- Al low me to correct a misstatement

, serious from the

economic standpoint, which is contained in the review of TheHaematites Of the Forest of Dean and South Wales (Memo Irs ofthe Geological Survey : Sp ecial Rep orts on the Mineral ResourcesOf Great Britain, vol . x) published in the January number Of y ourj ourna l .The reviewer states that the author sees no hop e for the resusci

tation of the mines under p rese nt conditions On the contrary ,thememoir under review describes the haematite - field of SouthWalesas a promising area for development . Thus In the haematitefield of South Wales recent y ears have witnessed a successfulrevival of iron - mIn In g, and the ore - fie lds g ive considerable promisefo r future development (p . 2) and again In view Of the highgrade of the ore , the comparatively large tracts of undevelopedground, and the successful mining at Llanharry in recent y ears ,it appears not improbable that the district will p roduce haematite o na larger scale in the future than it has done in the past (p .

As a matter of interest, I may add that new explo rations forhaematite in the Llanharry district, undoubtedly stimulated by theo fficial geo logical investigation of the area, have already commenced .

Yours faithfully ,T . FRANKLIN SIBLY .

ARMSTRONG COLLEGE , NEWCASTLE - UPON - TYNE .

Jan uary 1 4 ,1 920

OBITUARY .

He n ry Charle sI

Be asle y .

THE lateHenry C. Beasley , who died at Liverp oo l on December 14,1919;at the ripe age of 83, was best known to geologists for his workin connex ion with the Triassic footp rints, esp ecially those foundin the Keup er beds at Storeton, Cheshire, and other quarries in theLiverpo ol district . He published a number of pap ers in the Proce edi n gs of the Liverp ool Geological Society recording his observations

,and as Secretary of the British Association Committee for

Obi tuary—Fran ci sco Jo sue

’

Pa scasi o Mor en o . 95

the Investigation of the Fauna and Flora of the Trias Of the BritishIsles

,he wrote a series of rep orts on the footp rints for whi ch heprop osed a provisional scheme of classification . In 1906 he was

awarded the p roceeds of the Barlow - Jameson Fund by theGeological Society of London for his geological work in thisconnexion . He was Secretary of the Liverp ool Geological Societyfrom 1890 to 1900, and President for the sessions 1887—9 , 1904—6,an d again 1908—9

,an d served as President of the Liverp ool

Biologi cal Society for 1901,

—2 . His fine collection Of footprin tswas recently purchased by Councillor C. Sydney Jones, M.A .

,for

the Free Public Museum of Liverp ool . Mr . Beasl ey was a most indefatigable and p ersistent worker at his favourite geological subj ects,such work bein g his relaxation from an active commercial career .His unselfish character an d his readiness at al l times to assist an yfellow - worker endeared him to al l who knew him .

Fran cisco Jo sué Pascasio Mo re n o .

BORN MAY, 1 852 . DIED DECEMBER , 1919 .

WE regret to ann ounce the death of our friend Dr._Francisco P.

Moreno,founder and for many y ears director of the La Plata

Museum . Born in Buenos Aires 67 y ears ago , he was half English ,his mother having been the daughter of an English botanist . Hewas a collector of natural history sp ecimens from his earliest y outh ,and he soon began an imp ortant series of exp lorations of Patagoniaand the region of the Andes, which lasted from 1873 until 1884 .

His first scientific pap er was a descrip tion of some p rehistoriccemeteries in Patagonia,

published in the Revue d’An throp olog iein 1874 . Three y ears later he gave his collection to the ArgentineGovernment, who used it for the foundation of the Anthropologicaland Archaeological Museum of Buenos Aires . In 1880 Buenos Ai resbecame the federal cap ital, an d in 1882 the city of La Plata wasestablished to rep lace it as capital of the p rovince . In 1884 theprovincial governor suggested to Dr . Moreno that he should organizea great newmuseum in La Plata, taking his anthropological collectionas a basis . The Special desire of his life was thus ful filled, an d hebegan to work at once, p lanning the building an d arrangin g for theacqui sition of more collections to illustrate the n atural history and

antiqui ties of the Argentine Republic . The excavation of the newdocks in the Pampa formation near La Plata esp ecially afforded an

opportunity for Obtaining a fine series of skeletons of the Pleistocene Mammalia . By 1889 the Museum was nearly comp lete, and inthe follo'wing y ear Dr . Moreno began to issue its well - known seriesof valuable publications . In 1893, an d again in 1894, Mr . RichardLydekker visited the Museum Officially to p repare an account ofthe fossil Mammalia from the Pampa and some earlier formations,

c

.9 6 0bita ary—Fran ci sco Jo su e

’

Pascasi o Mor en o .

which appeared in the An ales del Museo de la Plata,Paleon t.

Argen tin a ,vols . ii and iii . In 1896 I sp ent a brief vacation there

,

and wrote a description of some remarkable Cretaceous crocodilesthen recently received from Neuqu

,en which occup ied another

p art 0 1 the An ales . In 1899 Dr Moreno came to London as ArgentineHigh Commissio n e i in connection with the Argentine—Chilianboundary dispute , which had been referred for arbitration to theBritish Crown . He then brought with him many fossils for comparison with the collection in the British Museum,

an d the p ieceO f skin Of an extinct ground - sloth from a cavern in Patagoni a,

wi th a Skull an d other remains of the horned tortoise M io lan iafrom Chubut, will be especially remembered . Dr . Moreno contributed a Note on the discovery of Mio lan ia and of Glossotherium(Neomylodon ) in Patagonia ’

to the GEOLOGICAL MAGAZINE,

Sep tember, 1899 . Return ing to La Plata he continued to directthe Museum for a few y ears longer, until he retired to BuenosAires and lived a quiet life , utilizing his rip e exp erience in furtherings chemes for the improvement of education .

“

Dr . Moreno ’s writings on the geography , anthropo logy , an d geologyo f his native lan d are imp ortant and varied

,but they give littleidea Of the extent of his labours for the p romotion Of science in

A rgentina . He was the unselfish frie nd an d help er of all whom heinduced to contribute to the publications Of the La Plata Museum ,

a n d of Argentine naturalists in general . He was ever ready to devotehis p rivate means to the advancement o f '

research, an d the greatcollection an d library at La -

‘Plata bear witness to his generosityas well as to his genius . He was honoured in this country byelection as Foreign Corresp ondent Of the Geological Society an d as

Corresponding Member of the Zoological Society of London . He was

also an Honorary Corresp onding Member of the Royal Geographical“

Society ,and received the Founder’s Medal In 1907 .

A . SMITH WOODWARD .

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9 8 Edi tor i a l Notes .

Museum o f Natural History , New Yo rk . The o ther n ew So ciety ,

the Asso ciatio n o f App lied Geo logists, should do much to fill upthe gap that n ow exists between pure geo logy an d the bran cheso f en gin eerin g an d o ther scien ces an d arts bearin g upon theexplo itation o f our min eral resources . We wish bo th these n ewsocieties a lon g and pro sperous career .

MANY o ld Cambridge geo logists both at home and abroad will beglad to hear that the Sedgwick Club has en tered on a career of

ren ewed activity after the in evitable p eriod o f eclip se, due to theWar . In the autumn of 19 14 the few remai n in g ordin ary membersheld a meetin g at which they app o in ted a comm i ttee

,mostly com

p osed of members o f the teachin g staff, under the chairman ship of

the Wo odwardian Pro fessor, to ho ld o ffice till the end o f the War,

with powers to elect ordin ary members . Last May term this com

mitte e exercised its p owers by n omin atin g sufficien t n ew members .

to fo rm a quorum,an d then extin guished itself. After this matters

pro ceeded in the o rdin ary way ,an d the Club is n ow as flourishin g ,

as ever, o r even more so,as shown by the fo llowin g commun ique

received from an o fficial source The Sedgwick Club has formeda - committee for directin g an d carry in g out a detailed study of thePleistocen e an d Ho locen e dep osits o f the Cambridge di strict withsp ecial referen ce to question s co n n ected with An cien tMan l n Britain .

Some y ears ago a similar committee o f the Club studied thedistribution o f the glacial boulders i n the district . The en thusiasmwith which that work was carried out, and the in terestin g resultsobtain ed

,recorded in a pap er by Messrs . Rastall an d Roman es

(Quart . Journ . Geo l . Soc .,vo l . lxv, 1909 , pp . 246—65) augur well

fo r the success o f the presen t un dertakin g .

WITH the op en in g o f Parliamen t the question o f the n atio n alizationo f min es has again reached an acute stage, an d app ears likely to

' bein the forefron t o f p o litics fo r some time to come . In the debateo n the Address the Prime Min ister sp oke words of so lid wisdom,

an d fo reshadowed mo st determin ed opp ositio n o n the part o f theGovernmen t to the pro j ects for bureaucratic co n tro l of our greatestin dustry . We have already drawn atten tion in these co lumn s to

the fallacies o f the prevailin g Fabian argumen ts in supp orto f n atio n alization o f coal - min es . It is curren tly rep orted that ,labour witn esses befo re the Board o f Trade Committee o n n o n

ferrous min in g have sp oken in favour o f n ation alizatio n as a remedyfor the troubles o f their own particular bran ch . Everythin g thathas been urged again st it in the case o f coal - min es app lies witheven greater force to metalliferous mi n es, and there is here an addedargumen t o f the greatest cogen cy . It is well - kn own to every o n e

at all conversan t with the subj ect thatmetalliferousmin in g , esp ecially

Edi tor ia l Notes .

n on - ferrous,o ffers much greater un certain ties than coal - min in g ,

and, in deed is almost always in evitably in the n ature of a gamble .Thi s is simp ly a matter of geo logy ,

an d it is un n ecessary to labourthe po in t . Now it is man ifestly imp ossible for the State to en terupo n such a hazardous typ e of sp eculation with the public fun dsas cap ital ; even the mo st academic eco n omist and the mosttheoretical socialist must recogn ize this fact, an d the in evitableresult o f the . in terferen ce o f the State and con tro l by a Governmen tdepartmen t would be the to tal stoppage of en terprise an d

developmen t in this direction an d a comp lete cessation o f an y pro ;duction of n on - ferrous me tals in this country , Such a state ofaffairs i sun thinkable .

>l<

THE Board of Trade Committee o n n on - ferrous metalliferous min eshas n ow comp leted the takin g o f eviden ce , and a rep ort is beingprepared which it is hop ed will be ready for presen tation in the courseof a few weeks . At the later sittin gs o f the Committee . somein terestin g eviden ce was given con cern in g lead,

zin c,an d bary tes .

Wi th regard to the last - n amed product Co l . J . V. Ramsden, of the

Shropshire Min es , Ltd .

, p o in ted out the n eed for improved methodsof preparation ,

and'

also for p rotection again st the dump in g . o f

cheap foreign material , if the bary tes industry in this coun try is tobe p reserved. Mr . J . Mitchell , of Wan lo ckhead

,described the

scheme for a very lon g deep - level gravity tun n el for the drainageof the Wan lockhead—Leadhills district . Much eviden ce Was givencon cern in g the presen t p o sition o f the lead - zin c mi ni n g industryin the North of En glan d . It was stated that the Ashover

b

Min esin Derbyshire are n ow worked almo st exclusively for fluor - s

‘par,

for which there is a go od deman d as a flux in metallurgical wo rk .

It app ears that in man y localities the visible supp lies o f w e are n ow

approachin g exhaustio n ,an d Professor Louis con sidered that the

allocation o f n ation al funds to investigation of the Melmerby ScarLimesto n e would be justified,

as in his op in io n this o ffers the mostpromi sin g prospects . In this con n exio n it may p erhap s be allowableto p o in t out that purely geo lo gical con sideration s are of greatimportan ce . If the ore came from below there should be a ten den cyfor it to accumulate un der such an imp ervious ro ck as the Whin Sill .Now it is well kn own that the sill is tran sgressive , o ccurrin g indifferen t p laces at very various stratigraphical horizon s . Hen cethe mo st likely p lace for o re would seem to

.

be in p laces where theWhin Sill rests o n a well - marked bed of limeston e , if such can befoun d . This eviden tly n eeds a close and

,detailed study o f lo cal

stratigraphy .

ORIGINAL . ARTICLES.

On an In ve rte d Mass o f Up p er Cre tace ous Strata n e ar

Le ighto n Buz z ard, Be dfo rdshire an d o n an Ove rlapo f the Up p e r Gau lt in that Ne ighbo urho o d.

-By F . L . KITCHIN , M.A . , Ph .D . , an d J . PRINGLE, F.GS .

(Con cluded from p .

C. IDENTIFICATION o n THE STRATA BETWEEN THE SILVER - SANDS

AND THE INVERTED MASS IN MR . HARRIs’s PIT .

N examin ation o f the section s at and n ear Shen ley Hill ,described above , thus provides the mean s for a comp lete in ter

pretation of the puzzlin g stratigraphical relation ship s seen in Harris’sPit . The inverted Upp er Gault and basal Cen oman ian limeston emasses have already been iden tified zon ally : the san d- beds distin gui shed as G an d F by Mr . Lamp lugh and tho se parts of his

bed D which are n ot of Cen oman ian age remain to be correlated .

The well - bedded,impure

,fin e sand (G) , overly in g the silver

sands may be reco gn ized as a thin an d probably denuded repre

sen tative o f the 6 ft .. bed o f streaked an d carbon aceous san d

underly in g the tardefurcata bed at Mil etre e Farm (No . Theo verlyin g stratum F

,a coarser and less well - bedded green ish

c lay ey san d, is here and there rather abrup tly separated frombed G, but in other p laces forms an upward con tinuation of it .The two may be con sidered to form part o f o n e dep osit . The coarsersand of F o ccurs as small shallow ban ks , which are discon tinuousin places ; when it is absen t the n ext higher bed, formin g part ofbed D ofMr. Lamp lugh (the part design ated D1 in Fig . is then incon tact wi th bed G, which in on e place where such a relation shipwas seen was reduced to 4 in ches in thickn ess .

The san dy beds G and F, o f pre - tardefurcata age , form’

the highestmember o f the Lower Greens an d presen t in this section . They are

overlain immediately by the un con formable basal bed o f the Upp erGault, with which we have become familiar in n eighbourin g section s .

For conven ien ce we refer to this bed at Harris’s Pit al . We haveseen that its developmen t, wherever it is n ormally overlain by theUpp er Gault Clay , is that o f a con tin uous basal bed of mixed com

position , variable in thickn ess, and with un even lower surface .At Harris’s Pit it shows less con tinuity and greater irregularity inits mode o f o ccurren ce . The clay which n ormally overlies it .withthe excep tion perhap s of a few little iso lated traces, had been locallyremoved by denudation before the overturn ed mass of strata becamedeposited in this p lace . The remn an ts o f the basal bed itself, whichformed the flo or up on which the inverted strata came to rest, mayowe some of their presen t irregularities to the same denudation ;but the con fused aspect of the bed is doubtless to be ascribed in

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1 02 F. L. Ki tchi n an d J Pr in g le

Upper Gault deposit . Mr . Walker broke up and examin ed a largeamoun t o f material without discrimin atin g between the blocks of

Cen oman ian limeston e and those from the bed o f earlier date .We co n sider that some sp ecimen s o f ammo n ites in that part of theWalker Co llection n ow p reserved at Cambridge, kin dly submittedto us by Mr . H. Wo ods for examin ation ,

belo n g without doubtto this earlier bed . They in clude Leymeriella regularis an d a fin elyribbed sp ecies of the same genus, derived from the tardefurcatabed

,which , as we have shown , was undergo in g denudatio n m the

immediate n eighbourho od at the time of the Upper Gault tran sgression . An o ther ammon ite is a ro lled fragmen t of a fin elyribbed Perisphin ctid, probably o f Upp er Kimmeridgian o rigin , o f

simi lar asp ect to some of tho se . found in the Lower Green san d o f

Po tton ; it may have been rederived from that or some similardep osit . We suspect that mo st o f the fo ssils o f Lower Cretaceouscharacter reco rded by Mr . Walker from bed D came

,in reality ,

from thi s basal Upper Gault, in which they o ccurred as derivatives,and n ot from the Cen oman ian limesto n e - len ticles . Further co llectin go n an exten sive scale would be n ecessary in order to allocate to theirright beds the sp ecies o f differen t ages which were thought byMessrs . Lamp lugh 85 Walker to illustrate a true commin glin g o f

life - forms .

The inverted len ticles o f Cen oman ian limeston e lie side by sidewith the masses an d patches o f the basal bed o f the Upp er Gault .The len ticles have been forced down in to the relatively soft materialo f the flo or up on which the in verted mass rests . The con stituen tparts o f the two beds, so in terlocked an d closely associated at thesame level, illustrate -

an un common stratigraphical relation shipo f much in terest . Some outer p ortion s o f the limeston e - l en ticlesare o ccasion ally seen to have become partly decomp o sed, an d maythen closely resemble the fin er material of the o lder bed . Theillusion is heighten ed by the p ebbles In the limesto n e an d by theferrugin ous stain in g of bo th matrices ; but the limeston e - len ticlesin all cases betray their true character by their in clude d fossils .

A few wo rds may be added here o n the subj ect o f the limon itesegregation s, bands C an d E

, parts of whi ch lie within the beds o f

Lower Green sand and Upper . Gault just discussed . Referrin g tothese iron ston e - sheets

,Mr . Lamp lugh stated There is cl ear '

pro of

that they were in existen ce as ro cky bands before the materialn ow overly in g them was dep osited.

” 1 In supp ort of this he calledin eviden ce the fragmen ts o f ironsto n e in corp orated in the brecciao f bed D and the p o lished an d worn surface of the iron -

pan

flo or underly in g the breccia . Referen ce was also made to somelarge blo cks o n the tip - heap o f

.

Harris’s Pit, en crusted on theirworn surfaces by adheren t oysters an d Serp ulae . Itwas in ferred that

1 G. W. Lamp lugh J . F.

“ Walker, On a Fo ssilife rous Ban d at the topo f the Lower Gre en san d n ear Le ighto n Buzzard (Bedfordshire ) Quar t.Journ . Ge o l . So c . , vo l . lix , 1903, p . 240 .

I n i ‘erted Mass of ,

Up p er Cr etaceous Stra ta . 1 03

these blocks belon ged to the iro n ston e - bed E,which either formed

part of the actual flo or from which the fragmen ts o f iron ston ein the overly in g breccia had been derived, or represen ted the kindo f local con temporan eous dep o sit in which they had their origin .

We may remark that bed E,when ever seen by us

,was o f such a

character as to be in capable o f furni shin g fragmen ts for the spo ilheap similar to the large blocks described .

Mr . Lamp lugh’

s later observation s, recorded in hispap er ofseem to give a clue to the o rigin o f the en crusted blo cks . In thislater commun ication there is the descrip tion o f a similarly en crustedsea - worn crag o f

“ iron ston e a few feet acro ss, within theg laucon itic green san d then seen overly in g the brachi opod - bed .

This is clearly an in durated p ortion o f the in con stan t Upp er Green ;san d bed . An examin ation of sp ecimen s of this ro ck obtain ed byMr . Lamp lugh shows that it differs essen tially from the tabularlimon itic ban ds, C an d E . In some of the sp ecimen s there is shown

'

a ferrugin ous an d siliceous in duration,probably o f seco n dary origin ,

addition al to the firm calcareous cemen tation seen in o ther partso f the rock ; but even these more iron - stain ed po rtion s do n ot in

reality resemble the limon ite - ban ds .

We thus recogni ze three distin ct categories amon g the ro ck - bodiesdiscussed by Mr . Lamp lugh under the headin g The Iron -

gritBands En umerating these in the chron o logical order o f theirformation we have

,firstly , the flat fragmen ts of iron sto n e (excludin g

the haematitic p ebbles) in corp orated as an o rigin al co n stituen tin the Upper Gault bed, D l secon dly , the in durated masses withworn an d en crusted surfaces fo rmin g part o f the bed o f UpperGreen sand and thirdly ,

the thi n un dulatin g and bran chin g sheetswhich have resulted from min eral segregation sin ce Glacial time .The disp osition o f these con n ected sheets

,o ccupy in g surfaces

whi ch mark two un co n formable jun ction s an d en closin g porti on so f beds belo n gin g to three widely differen t geo lo gical dates (oneo f the beds bein g in inverted position ), proves con clusively thatthe ban ds C an d E are n ot an origin al part of the series .

‘ Thesmoo th surfaces o f the sheets are n ot in compatible with the laterin troduction of the limo ni te .D. RELATIONS OE GAULT AND CENOMANIAN AT THE MAIN OUTCROP .

The eviden ce so far obtain ed showed that a basal Cen oman ianbed o f sp ecial typ e fo rmerly existed at the top o f the outli er at

Shenl ey Hill , and that the remn an ts of it - seen there i n Invertedposition owed their preservation to the fact that they had becomesealed up un der

_a pro tective mass o f Upper Gault clay . It became

desirable to ascertain if, an ywhere towards the south - east and south ,a similar bed at . the base of the Chalk escarpmen t replaces the

1 Excursion to Leighton Buzzard Proc. Geol . Asso c . , vo l . xx , p t . vi ,

1908 , p . 475 .

2 G . W. Lamp lugh J. F. Walker, op . cit . , 1903, p . 240 .

104 F.-L. K i tchi n an d J . Pr i n g le

Cambridge Green san d of the coun try towards the n orth - east . N0

in formation on this po in t could be obtain ed from published writin gs,and an examin ation o f the groun d so on showed that the base o f theChalk was n ot to be seen in an y n atural expo sure: The lowerslopes o f the escarpmen t are covered with a dep o sit o f chalkydownwash o f variable thickn ess, an d the lin e o f outcrop of the basalbed is either con cealed ben eath this or is situated i n the flattergroun d under a cover of Boulder clay .

The outcrop of the Cambridge Green sand, at the base of the ChalkMarl

,is kn own to extend towards the south—west as far as the

n eighbourho od of Sharp enho e , east o f Harlin gton . Here the bed isthin n in g, and is developed as a blui sh -

grey sandy clay ,about a fo ot

i n thickn ess, with green grain s an d man y n odules . We began our

in vestigation s just south o f this p o in t, an d p robed the ground byborin g or diggin g at several locali ties between here an d Wen dover.

The result was to show that the eviden ce for a break in the sequen ceat the base of the Chalk, with sign s o f erosion , dimin ishes in a southwesterly direction .

At a Sp ot on e mi le south east ofHarlin gton Church the basemen tbed of the Chalk, as shown by fragmen ts brought up by a han d- borin gto o l, was reached at a dep th of 10 feet below the surface . It IS overlain by 3 feet o f cream and pale buff- co loured Chalk Marl , grittyan d slightly glauconi tic in the lowest fo ot . The basemen t bed i s

here reduced to a lay er which we estimate to be 2 to 3 in ches thi ck .

It con sists of small well - rounded quartz - grains, black crumbsan d po lished grain s phosphate) , set in a fin e creamy calcareouspaste con tain in g pebbles (up to 4 in . in diameter) of ro lled quartzgrit, fin e quartzose sandston e, and suban gular white chert, as wellas black phosphatized fragmen ts . This bed is underlain by paleUpp er Gault Clay , assumi n g a darker bluish tin t at a lower level .At Kateshill

,3miles n orth - west ofDun stable, a po or exp o sure in

the road- cuttin g on Watlin g Street en abled us to ascertain that thebasemen t - bed of the varian s Chalk is an in durated grey calcareoussan dston e with numerous small cream and grey - co loured phosphaticn odules, up to g in . in diameter . This bed is underlain by the palecalcareous clay of the Upp er Gault, with darker bluish clay at a

lower level,as at Harlin gton .

At To ttern ho e and Eaton Bray the outcrop o f the base of theChalk is masked by a thick dep osit of chalky downwash . It waseviden tly due to an error that an outcrop of Upp er Green san d at

the village o f Eaton Bray was represen ted on the Geo logical Surveymap . The most careful in qui ry failed to reveal an y trace of it .A borin g made in 1913—14 at Eaton Bray Nurseries (own ed byMessrs . Wallace) on the Chalk outcrop as shown o n the map , showedthe presen ce of pale Gault Clay below the Drift . The Lower Greensan d was reached at a dep th of 243 feet below the surface . We

are indebted to Mr . Wallace, jun . , for allowin g us to examin e samp les

of the cores in his possession and for commun icatin g to us the details

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1 06 F. L. K i tchi n an d J . Pr i n g le

in which are n odules con tain in g a remaui e group o f fossils ;hence thetran sgressive strata are to be classified as rostratus Gault . The sectionat Harris’s Pit proves that still higher beds of the rostratus zon ewere dep osited . They are o f a marly character an d con tain an

ammo n ite - faun a (the cati llus”

. faun a) represen ted in the Upp erGreen sand of Wiltshire, below the Pecten asper beds, an d in theUpp er Green sand o f the Isle o f Wight just below the Chert beds .

These highest Gault strata are n ow on ly exp osed at Shen ley Hil lin the inverted mass at Harris’s Pit. If p resen t i n situ an ywherein the higher part of the hill they are con cealed ben eath the Drift .The bed o f green san d o bserved by Mr . Lamp lugh to be in ter

calated lo cally between the brachiop od - bed an d the Gault Clay ,

in the inverted mass,has y ielded fossils which , so far as they are

kn own , indicate defin itely a zon al p o sition above the Gault ; an d

we con sider that this bed may be correlated provisio n ally with thePecten asp er Green san d . The abrup t tran sition from the clay to thesand suggests that the . jun ction between them may represen ta line o f n on - sequen ce ; a con siderable thickn ess o f strata in themore expan ded aren aceous series o f Wiltshire app ears to be unrepresen ted here . The in co n stan t o

o ccurren ce of this Upp er Greensand bed

,with rap id thicken in g , an d the fact that where it is absen t

the basal Cen oman ian bed with brachiop ods is separated from the

rostratus Gault on ly by a thin layer of iro n ston e o f later origin ,

p o in t to a denudation o f the upp ermost p art o f _the Selborni an

series prior to the dep osition o f the basal Cen oman ian bed, witha corresp ondin g degree o f n o n - sequen ce . This perio d o f denudationproduced still more far - reachin g effects in the region of the CambridgeGreen sand

,In parts of whi ch , at least, _the removal of much o f the

Upp er Gault was also in vo lved .

The n ext bed to be considered is the brachiop od - bed, which

con sists. of iso lated limesto n e—len ticles , formin g the lowest part ofthe in verted mass . This affords amp le eviden ce o f its age an d o f

the con dition s under which it was dep osited . Its in digen ous faun ais that of the sub—zon e of Catop ygus columbarius at the base o f theCen oman ian stage as '

un dersto od in this coun try ; an d it has n ot

been p roved that the bed con tain s fo ssils derived from o lder strata .

As already stated,the Lower Cretaceous species reco rded by

Messrs . Lamp lugh Walker from the brachiop od—bed were 111 all

probability found in the basal bed o f the Upp er Gault , where theywould o ccur as derivatives . It is improbable that the strata whi chformed the true source o f these o lder fo ssils were exp o sed to

den udation at the time when the basal Cen oman ian deposit waslaid down .

We have remarked up o n the clo se similarity o f the limeston elen ticles to the gritty limesto n e found in part o f Northern Franceat the base of the varian s zo n e . Cap tain W. B . R . Kin g , who sen tover sp ecimen s o f this ro ck durin g the recen t War, i n forms us thatit o ccurs at Matrin ghem in isolated len ticles oc

'

cupy i n g ho llows i n

I n ver ted Mass of Upp er Cr etaceou s Strata .

a flo or of Devon ian san dsto n e . This compares closely with themode o f occurren ce o f the similar len ticles at Shen ley Hill an d adds

s tren gth to our in feren ce that we have here a basemen t—bed o f thevarian s Chalk , laid down durin g the p eriod of early Cen oman ianmovemen t and tran sgression . NO later dep osit o f Cretaceous age

i s preserved at Shen ley Hill .The above brief descrip tion o f even ts durin g Cretaceous time

e xp lain s much con fusio n i n the accoun t of the strata o ffered byMessrs . Lamplugh Walker . ,The brachiopod - bed (D) of tho seauthors was ascribed by them to the Lower Green san d . In realityit con sists of rock -masses belon gin g to the basal bed of the Chalkan d the basal bed o f the Upp er Gault . The idea of a p ecul iarfaun al assemblage , foun ded o n a co llectio n of sp ecimen s obtain edfrom the ro cks o f bo th zon es , was boun d to be erro n eous, particularlyin

“View of the fact that some Lower Cretaceous sp ecies were foun dwhich were n ot in digen ous to either Of these horizon s . Mr . Walker’srecognitio n of so man y links with the Tourtia - faun as o f theCon tin en t

,whichever local Tourtia it might be , n ow gain s a n ew

sign ifican ce . Tran sgressive basemen t beds formed under con ditio n so f active erosi on are likely to co n tain sp ecies derived from an yfossiliferous stratum of earlier age exp o sed to den udation at the time .

B. EVENTS DURING AND SINCE GLACIAL TIME .

It is eviden t “that before the advan ce of the ice—sheet the Upper‘Gault in the n eighbourhood o f Shen le‘y Hill was capp ed in p lacesby the remn an ts o f the Upp er Green san d, with the len ticles o f basalCen oman ian age extendin g over bo th . It is impossible to saywhether an y of the Chalk. Marl here had still survived the ordin aryprocesses of subaerial denudatio n . So far as the overturn ed mass

of strata is con cern ed, n o Chalk Marl was p resen t .The inversion of the sheet of strata n ow seen in an abn ormal o rder

o f succession at Harri-S’s Pit must be regarded as an effect of theglaciation o f the district . The elevation o f the groun d probablyo pp osed an o bstacle to the advan cin g ice - Sheet

,

1 with the result thata huge mass of rostratus Gault and its thin cappin g o f later stratabecame detached

,carried forwards towards the south o r south - east

and comp letely overturn ed up on a flo or formed,o n the lower groun d,

by the basal part of the Upper Gault . It seems improbable that sucha large mass could have been tran sp o rted _

far from its o rigin al Site .It is remarkable that there are so few Sign s o f disturban ce at the

presen t base of the inverted beds ; and although there is sufficien teviden ce of squeezin g , disrup tio n ,

an d con fusion in the p resen tstate of the topmost bed o f the substrata,

this 13 on ly such as mightresult from simp le crushin g , without an y co n tinued forward movemen t of the tran sp orted mass after it reached its n ew restin g place .

1 Comp are remarks by H B . Wo odward , The Chalky Boulder clay an d

the Glacial Phen omen a o f the We stern Midlan dCoun tie s o f En g lan d GEOL .

MAG. , 1897, pp . 495~6 .

1 08 F. L. K i tchi n an d J . Pr i n g le—Q

We may suggest that the coheren ce o f the clays and san ds wouldbe in creased by freezin g, an d that the tran sp orted Sheet o f stratamay have been moved very slowly in to its n ew p osition while held

'

firmly in the ice - stream, and dep osited up on sn ow or sn ow - coveredice . The subsequen t meltin g would proceed so gradually as to

let down the mass on to its n ew substratum with a min imum o f

disturban ce . It may have been at that time that the limeston elen ticles of the inverted upp er surface of the boulder became forceddown by pressure in to the y ieldin g material of the flo or.

While n o kn own agen cy excep t the movemen t of an ice - sheetis adequate to have produced the result n ow seen

,a con sideration

o f the exact modus op erandi may be left to those who have had moreexperien ce in the study o f glacial phen omen a . Sir Archibald Geikiehas commen ted on the difficul ty of con ceivin g how exten sive thinsheets of soft strata can have been p loughed out o f their p lace andpushed fo rward .

1

This strikin g example of glacial tran sportation falls in to lin ewith ' the similar in stan ces alon g the tract of coun try to the n ortheast . There is the well - kn own mass of Cretaceous strata at RoslynHill Pit, Ely ,

discussed in pap ers by the late Osmon d Fisher an d byPro fessor T . G. Bon n ey 2 while at Biggleswade , n ear Bedford,

a mass of Amp thill Clay n early 70 feet thick has been foun d in corp orated in the Boulder- clay .

3 Numerous o ther examples of the

tran sp ortation of large masses o r cakes of Jurassic and

Cretaceous rocks in the Midland area have been recorded by variouswriters f

‘ We may also refer to the boulder o f Cretaceous strata240 yards in len gth at Leavad, in Caithn ess .

5

It is imp ossible to say how far glacial erosion ,subsequen tly to

the removal of the inverted strata to their presen t p osition , may havereduced the thickn ess o f the mass . It may be remembered, however,that the faun a found at the presen t top o f the reversed beds of Gault .Shows that the who le o f the Upp er Gault in ‘

situ at Shen ley Hillcan have been little mo re than 40 feet in thickn ess . Hen ce it app ears:certain that in relatio n to its area,

the who le mass must have beenthin from the time of its detachmen t . Again , we prefer to leavea discussio n of this purely glacial asp ect of the problem to those whoare better qualified to o ffer an opin ion .

1 In a discussion on Mr. Home’

s p ap er, cited be l ow, p .

2 0 .

"

Fisher, On Ro slyn or Ro swe l l Hil l Clay -

pit n ear Ely GEOL

1868, p . 407 . T .

“

G. Bon n ey , Note s o n the Ro sl yn Hill Clay-

p it GEOL .

MAG . , 1872 , p . 403. Also Cambridgeshire Geo logy ,1875 , p . 69 .

3 H. Home , On a tran sp orted mass o f Amp thil l Clay in the Boulder - clay

at Bigg le swade , Bedfordshire Quart. Journ . Geo l . Soc. , vo l . l ix , 1903, p . 375 .

4 For referen ce s to some strikin g cases see H. B . Wo odward, op . crt . , 1897,

495 .p5 R . G. Carruthers, On the o ccurren ce of a Cretace ous Boulder of un usual

siz e at Leavad, in Caithn e ss Summary of Progress for 19 10 (Mem . Ge o l .

19 11 , p . 80 . D . Tait, On a larg e g lacially tran sp orted mass of LowerCretace ous Ro ck at Leavad , in the Coun ty of Caithn ess Tran s. Edi n .

Ge o l . So c. , vo l . x, p t . 1, 19 11 .

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1 10 F. L. Ki tchi n an d J.P r in gle

to the basemen t - bed of the Upp er Gault and to the basemen t - bedof the Cen oman ian stage, as understo od by En glish geo logists(sub - zon e o f Catap ygus co lumbarius) .

(2) The Cen oman ian bed is presen t in the form of iso lated len ticlesof limeston e . Although n o comparable stratum can be foun d at

the presen t outcrop , which has receded from the area where condition s produced this particular typ e o f dep o sit , the bed has a closelitho logical coun terpart in Northern Fran ce (Matrin ghem) , wherethere is an almo st iden tical bed at the base o f the varian s zon e .

At Harris’s Pit the Cen oman ian bed, an in con stan t lay er o f

Upp er Green san d fo rmerly seen above it, and an overly in g mass of

Gaul t Clay o f rostratus age are in an in verted order o f succession .

There is a jun ction o f erosion and n on - sequen ce between the Gaultan d the Cen oman ian bed .

(4) The n o rmal un broken passage from Lower Green sand to“

Lower Gault (in terrup tus zon e) is shown south o f Leighto n Buzzardin mo re comp lete developmen t than in other section s hithertodescribed in this coun try . The series here in cludes a san dy passagebed o f tardefurcata age (with the Leymerie lla - faun a) overlain byin terruptus clay , as in

‘ parts o f the Con tin en t .T he Lower Gault has n ot been seen at Shen ley Hill, where

there is an overlap of Upp er Gault upon the Lower Green sand .

The basal bed o f the Upper Gault is here o f mixed and variablecon stitution ,

with much coarse material , con tain in g relics o f theden udation o f the tardefurcata bed . It passes up first in to clay ,

then in to more marly clay con tain in g the early rostratus faun a

o f Bed IX of Fo lkesto n e , the highest Gault as y et seen at Shen leyHill i n situ . The hill forms an outlier o f the upp er rostratus beds .

(6) At Harris’s Pit the overturn ed mass o f strata rests upon thebasal bed of the Upp er Gault, with which the Cen oman ian limeston e - len ticles have become in termin gled . In n eighbourin g section sa thin remn an t of the overly in g Upp er Gault Clay is presen t inn ormal sequen ce .(7) The f ossils recorded by Messrs . Lamplugh “ Walker as

o ccurrin g in the brachiop od - bed, o f alleged Lower Green san d age ,

came in part from the Cen oman ian limeston e an d in part from thebasemen t - bed of the Upp er Gault . The earlier of these strata wouldbe likely to y ield Sp ecimen s derived from the tardefurcata bed an d

from lower zo n es, thus accoun tin g for the supposed in termin gledcharacter of the faun a o f the brachiopod—bed .

(8) It may be roughly estimated that the overturn ed mass was

origin ally some 250 yards in' len gth, in n orth an d south extension ,

an d .upwards of 150 yards in breadth ; its westerly boun dary hasn ot y et been

'

reached in the san d- workin gs .

(9 ) The in verted mass of strata became removed from its origin alsite durin g the glaciation of. the district, as in the case of the tran sp orted masses at Biggleswade, Ely , an d elsewhere . It was probablyderived ‘ from the higher , groun d to the n orth or n orth - west - o f Its

In ver ted Mass of Up p er Cr etaceou s Stra ta .

presen t locatio n ,where the outlier at that time was capped by the

basal Cen oman ian bed,o r by remn an ts of it .

(10) Thin iron ston e - ban ds which form a"

con sp icuous featurein the section atHarris’8 Pit are develop ed prin cipally alon g surfacesof stratigraphical discon tinuity . Their disp osition within the strataof both the n ormal an d the inverted parts o f the sequen ce showsthat they were formed by min eral segregation subsequen tly to theglaciation .

The presen t study emphasizes a lesson . Sin ce the who le fabricof stratigraphy is built up on the determin ation of age

- relation shipsamon g superimposed dep osits, it fo llows that an essen tial o f soundstratigraphical work lies in the full utilization - o f all availablepalaeon to logical criteria . If these be n eglected, the data for correctco n clusion s are in comp lete, and the investigator may thus permi thimself to be deceived by the app aren t simplicity of a - stratified

series . The stratigrapher is to o often dismay ed by the complexitiesof paleeon to logical classification an d n omen clature ; but thedetermin ation of the age Of successive strata do es n ot n ecessaril ydeman d an ex cursion

'

in to this forbiddin g domain . It can usuallybe compassed without the n amin g of

_

sp ecies . Nevertheless, somekn owledge of the faun al characterization o f zon es

,-as well as

fami liarity with the prin cip les u n derly in g the right app licatio n o f

that kn owledge, must always form part of the in disp en sableequipmen t for stratigraphical work . The trouble invo lved in theuse of these mean s for age

- determin ation , however irksome it mayseem,

can n o more be evaded than that which6 must n ecessarilybe taken in the study . of litho logical characters and relatio n s, fromwhich are deduced ,the condition s un der which sedimen tation has “

taken placeIn the case o f a composite fossil faun a co n sistin g o f derived and

indigen ous elemen ts, the criterion of age is to be sought amon gthe zon ally latest life - forms and n ot amon g the earlier on es . Thedetermin ation of age is then based up on previous experien ce of

un iformi ties, bo th as regards bio logical facies and zon al restrictio n .

Its accuracy is thus directly prop ortion ate to the kn own in

variability o f the faun al and chron o logical in ter relation .

The elemen tary truths embodied in these remarks have beenbrought home to us by man y workers Sin ce

_the days o f WilliamSmith , in more recen t y ears by the illumin atin g researches of

Charles Lapworth , S. S. Buckman , A . W. Rowe , an d o therinvestigators ; but there is p erhap s n o illustratio n of them more

convin cin g than that afforded by the study Of Shen l ey Hill .

Fin ally , we desire to express our in debtedn ess_

to those who havekindly given help in the presen t investigation , to Mr . GregoryHarris and Mr . George Garside , who p ermitted us to visit their_

sand -

p its ; to Mr . Hen ry Wo ods for a list of fossils in the

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1 1 4 Dr . F. R . Cowp er R eed

The fossils, whi ch are scarce and mo stly fragmen tary ,are in a

p o or state .o i preservation , con sistin g either o f crushed in tern al castsor extern al impression s, with the shell sometimes retain ed '

as a

thin film .

It was felt that a more detailed examin ation of the materialthan was given in 1900—1 might y ield fuller an d more defin iteresul ts

,an d Pro fessor Hughes accordingly en trusted me in 19 15

with the task, as the sp ecimen s had been dep o sited in the

Sedgwick Museum . A large n umber o f fragmen ts have beencarefully broken op en or sp lit, an d by this mean s it has beenp ossible to augmen t to a con siderable exten t the list whichProfessor Hughes gave in 1901 , and to fix with more certain tythe stratigraphical p o sition of the beds . The faun a proves to beo f p eculiar in terest, an d in the almo st to tal ign oran ce o f the geo logyof this district o f Siam the fo llowin g n o tes may be Of value tofuture investigators in these parts .

Pron orites aff. cyclolobus (Phillip s) . (Pl . II , Fig .

The lateMr . G. C. Crick kin dly examin ed fo rme the sin gle specimeno f a cephalop od in the co llectio n which shows a suture - lin e distin ctly ,and he con sidered that the Shell was referable to the genus Pron oritesand allied to the Carbon iferous sp ecies Pr . cyclolobus (Phillips) . 1Our sp ecimen shows about the last quarter o f the outer whorlan d a p ortion of the body - chamber four suture - lin es are preserved .

The more stron gly marked horsesho e - Shap ed saddles an d the blun teror even roun ded second lateral an d accessory lobes, and the factthat the first an d seco n d lateral saddles n early touch resp ectively .

those o f the precedin g suture - lin e an d overlap the bases o f the

p recedin g adj o in in g lobes , are features which distin guish it fromthe typ ical Pr. cyclo lobus . The who le shell when perfect must havemeasured about 20—25 mm . in diameter .

Pro lecan ites sp .

Some p o or impression s o f the exterio r an d some flatten edimperfect in tern al casts o f a gon iatite may p erhaps be referable

.

to

a sp ecies o f the gen us Pro lecan ites rather than to Pron orites, but thereferen ce is un certain . The shellwas apparen tly disco id an d laterallycompressed with all the whorls (6—7) exp o sed in the wide , shallow,

op en umbilicus . The overlappin g of the whorls app ears to havebeen slight, but the outer who rl in creases more rap idly in size thanthe in n er on es, an d there are some traces o f a more comp licatedsuture - lin e than in Pron orites . Perhap s P . comp ressas (Sow. )

2and

P . mir o lobus (Phill . ) 3 may be compared with it ; the latter is1 Phill ip s , Geo l . Yorkshire , 1836, p t . i i , p . 237, p l . xx , figs . 40 - 2 . Fo ord

an d Crick , Cat. Foss . Cep h. Brit. Ill us , p t. iii , 1897 p . 264 , te xt - fig . 125 , p . 261 .

2 Sowerby , M in . Con ch. , vo l . i , 1813, p . 84 , p l . xxxviii . Fo ord Crick,Cat. Foss . Cep h. Brit. Mus , p t . iii , 1897, p . 252 , fig . 12 1 .

3 Phil lip s, Geo l . Yorks, p t. ii, 1836, p . 236, p l . xx, fig . 43; Fo ord Crick,Op . cit . , p . 254 .

Carbon ifer ou s Fo ssi ls from Siam .

rec'

orded by Crick 1 from the Coddon Hill Beds o f'

-Devo n shire'

,which

are Clo sely similar litho logically as well as faun istically with theSiamese dep o sit, an d the same Sp ecies .

is a characteristic on e of thePo Sido n ien schiefer o f the Harz an d o f Geigen ,

n ear Hof . Thereis. apparen tly an o ther sp eci es of Pro lecan ites o r more p robablyNomisrn oCeras rep resen ted in the co llection ,

but it is to o po orlypreserved for determin ation .

Glypkioceras (l ) sp .

On e slab o f rock co n tain s man y much—crushed casts an d

impressIOn s o f a subglobose cephalop od with a broad roun ded backand large con vex outer who rl , Slowly in creasin g in Size

,but almost

comp letely overlapp in g the in n er who rls, which are exposed in

a small, deep ,umbilicus with rectan gular (l ) edges . A

'

few widely'

distan t con cen tric“

co n strictions cross the outer whorl . This shellmay belon g to the genus Glyp kioceras (of . Cl . mutabi le or to

Castrioceras (of . C (? ) Kayseri Loczy ,

3of the Carbo n iferous o f

Chin a) , but there is n ot sufficien t o f it kn own to determin e itsrelatio n s . Man suy

4has doubtfully reco rded the gen us Glyp kioceras

from the Carbon iferous o f Eastern Yun n an , but it_

i s a wellrepresen ted genus in the Po sidon ie n schiefer o f the Harz .

Pleurotomaria (Mourlon ia ) aff . con ica Phillip s . (Pl . 11 , Fig .

There Is On e p ortio n o f a shell o f '

a P leurotomaria half imbeddedin matrix an d somewhat crushed, but it can be seen to have beena low trochiform Shell o f 4—6 who rls, rap idly In creasmg In Si zeand with an ap ical an gle o f degrees . Each whorl is rathersharp ly an gulated at the ban d, which in the basal whorl is p eripheral ,but on the upp er who rls is situated a little distan ce above thesuture - lin e . The ap ical surface o f the whorls is slightly excavatedjust above - the band,

but becomes gen tly convex n ear the suturelin e . Below the ban d the umbilical surface of

_the basal whorl

seems to have been stron gly con vex,but it is rather crushed an d

has a co n cen tric fracture simulatin g a revo lvin g ridge . The margin sOf the ban d are sharp and p romin en t . The surface of the whorlsis crossed by stron g , regular, tran sverse , curved

_

striae, which are of

almost equal size an d n early equidistan t, an d they meet the band o n

the ap ical surface at about 30 degrees o r less, but apparen tly are

n early at right an gles to it below . Dimen sio n s : height (estimated)about 17 mm . ,

basal diameter about 19 mm . With regard to its1 Crick , Quart . .Iourn . Ge o l . Soc vo l . lv , 1895 , p . 652 .

2 Phil lip s, Geo l . Yorks p t . ii , 1836 , p . 236 , p l . xx , fig . 26 . Crick , Cat. Foss .

Cep h. Brit. Mus , p t,iii , 1897 , p . 181 (an d re fererice s ) . Ho lzap fe l , Pa loeon t.

Abhan dl . , vo l . . v , p f . i , 1889 , p . 29 , t . ii , fig s . 2 6 .

3 Loczy , Wiss . Ergebn . Reise Szechen y i in Ostasien , Bd . iii , 1898 , p . 44, t . 1,figs . 7, 7a . Sche l lwien in Futterer

’

s Durck As ien , Bd . iii , Lief. i , 1903, p . 139 ,t . i

, figs . 1 , 2 .

fi

Man suy , Mem . Surv . Ge o l . In dochin e , vol . i , fasc. ii , 19 12 , p . 87, p l . xvi ,

g . 5 .

1 1 6 Dr . F. R . Cowp er Reed

affin ities,

” this shell seems to resemble P l . con ica Phillips ,1 o f theCarbon iferous Limeston e

,which Mrs . Lon gstaff 2 thinks may belon g

to the subgenus Treckni an n ia rather than to Mourlon ia sen s . str .

The figure o f a shell n amed P l . vittata Phill . by Ho lzapfel 3 alsobears a con siderable resemblan ce to our sp ecimen ,

an d we may alsompare the species P l . (Mourl ) Cayeur i Man suy ,

4described from

the Din an tian of Eastern Yun nan .

Euomphalus cf . subcircularis Mansuy . (Pl . II , Fig .

Several specimen s o f small p lan orbiform Shells,with an average

diameter o f about 8 mm . , may perhap s be compared'

with Man suy’

s

E . subcircularis5from the Carboni ferous of

_

Eastern Yun n an ,

though there are man y Europ ean species which may be allied .

The shell is co iled in a flat sp iral o f 5—6 rounded whorls,n early

subcircular in section an d in creasin g very slowly in size, with a

submargin al carin at ion on the upp er surface dy in g out towardsthe mouth . The sp ire is rather sun ken

,bein g slightly depressed

below the level o f the outer who rl, and the op en umbilicus is alsocon cave . Rather stron g con cen tric striae cross the whorls .

Helmin tkockiton of . p rison s (Mun ster) . (Pl . II , Fig .

There is o n e symmetrical sub - semicircular and subcon ical plate ofa sp ecies o f Helmin tkockiton measurin g 6 mm . in diameter, whichagrees in gen eral characters with the an terior p late o f H . p rison s

(Mun st ) as described and figured by De Kon in ck .

6 The slightlyraised small median apex pro j ects a little behin d the an gulatedp osterior en d, an d from the ap ex there radiate o n each side a pair ofsm argin al fin e straight gro oves separatin g low rounded ridges .

A rather large crescen tic Shelly pro cess o r shelf pro j ects at a lowerlevel behin d the p osterior e n d o f the p late “, an d is crossed bya n arrow trian gular fissure which is doubtfully an origin al feature .

Paralle lodon afl . corrugatus De Ko n in ck . (Pl . II , Fig .

There is o n e right valve o f a shell which is referable to the genusParallelodon ,

but like the o ther fossils it isbadly preserved . In Shapeit is tran sversely rhombo idal the in ferior margin is gen tly sinuated ;the posterior e nd is roun ded—subtrun cate ; the beak is broad, low,

obtuse,an d Situated at about o n e - third (o r less) the len gth o f the

Shell and the surface is o rn amen ted with very fin e radial lin es an don cen tric growth- lin es, the latter becoming stro n ger n ear themargin .

In len gth the valve is about 155 mm .

,an d in height about 9 5 mm .

It app ears to be allied to P . corrugatus De Kon in ck, as descr’ ibed

1 Phil lip s, Geo l . Yorks , vo l . ii , 1836 , p l . xv ,fig . 2

2 Lon gstaff, Quart. Journ . Ge o l . Soc . , vo l . lxviii , 19 12 , p . 303.

3 Ho l zap fe l , Pa lman t. Abhan dl . , vo l . v , p t. 1, 1889 , p . 50 , t . vi , fig . 14 .

4 Man suy , Op . cit . , vo l . 1, fasc . i i , p t. i i , 19 12 , p . 89 , p l . xvi , fig . 7 .

5 Man suy , op . cit . , vo l . 1, fasc . i i , p t. ii , 19 12 , p . 105 , p l . ix , figs . 3a—3d.

5 De Kon in ck, Faun a Ca le . Carb. Be lg . , vo l . iv,1883, p . 199 , p l . 1, figs . 37—48

p l . l i , fig . 36 p l . l iii , figs. 21—9 .

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1 1 8 Dr . F. R . Cowp er Reed

degrees . Body o f Shell very gen tly con vex,sharp ly marked Off from

an terior ear ; umbo acute, directed forwards , situated at abouto n e - third len gth o f hin ge - lin e o r subtermin al . Surface of Shellcovered with stron g regular, con cen tric un dulation s, trian gularin section , o f equal or 1

subequal stren gth an d size , becomin g lessregular on an terior ear an d smaller an d weaker on p osterio r portiono f shell, with fin e , straight, radiatin g lin es cro ssin g them in middlepart o f valves . Some fin e co n cen tric lin es are also o ccasion allypresen t on the undulatio n s . Dimen sion s : (1) height (oblique) ,30 mm . ; len gth (parallel to : hin ge - lin e) , 23 mm . (11) height(oblique) , 80 mm . len gth (parallel to hin ge - lin e) , 55 mm .

FIG . 1 .— P osidon omya Becheri Bron n , var . n ov . siamen sis .

Remarks — This is the sp ecies which. o ccurs on . the small brokenimage of aBuddha from the temp le of Bah Nah . There are seve ralmore or less p erfect examp les ofvarious sizes o n it, an d o n e Shows bothvalves in juxtaposition andwell preserved . The largest sp ecimen isimp erfect . The orn amen tation is like that of Posidon omya BecheriBron n 1 but with regard to the characters o f this genus there '

is

con siderable diverSity '

o f op in io n . Zittel says it has n o ears , whereas1 Whe e lton Hin d, op . cit. , vo l . ii , p . 27, p l . vi , figs. 1 1—15 .

Carbon iferous Foss i ls fr om Siam .

Wheelton Hin d says it has a rounded an terior ear and a compressedexpanded p osterio r ear . The an terior ear is well seen in our completespecimen ,

which has bo th valves preserved, and in this examp le theear seems relatively wider and larger than in the o ther sp ecimen s .

In the largest Shell the umbo seems subtermin al , and the who le shellmore elon gated and less rhombo idal . Distortion often affects theshap e o f Sp ecimen s o f Posidon omya,

and some o f the difficulties an d

differen ces of op in ion with regard to its characters result from thiscause . There is a shell figured by De Ko n in ck as P . p licata

1 whichbears much resemblan ce to our sp ecimen s, an d the Culm shellsfrom North Devon

,which Phillips 2 figured an d described as

P . Becheri an d P . lateralis Sow . may also be compared . Dien er 3

has referred some in distin ct casts in the An thraco lithic beds of

Spiti to‘ this genus, but o therwise it do es n ot seem to have beenrecorded from the Carbon iferous o f Asia .

The discovery o f Sp ecimen s of this shell at Kuan Lin Soh ina ro ck “

precisely similar to that o f the image from Bah Nah,and

their o ccurren ce in the same rock as the rest of the faun a , fixesthe age of the sp ecimen s in the image .

Posidon orn ya (l ) of. radiata Wh . Hind .

There is an imp erfect impression o f the greater part of the leftvalve of an o bliquely ovate Shell about 1 1 mm . high,

with a gen tlycon vex surface marked by fin e con cen tric lin es an d straight ,radiatin g , broad ribs which are o f rather un equal stren gth and

width , bein g sharp , n arrow, an d stron g n ear the po sterior margin ,

but low an d weak in .the middle . So far as its characters can be

determin ed,there is a resemblan ce o f this shell to Posidon omya

radiata Wh. Hind,

4 but the gen eric referen ce of this species seems

op en to doubt .

Pseudamusium cf. p rcetenue Vo n Ko en en . (PI. 11 , Fig .

There is on e right valve of a species o f a pectin o id shell represen tedin the co llection by an in tern al cast and extern al impression ,

whichresembles Pecten prcetenuis Von Ko en en 5 from the Culm of German y .

It measures 13mm . in len gth and 10 mm . in height . In shap e it isobliquely oval and very in equilateral ; the beak is small , acutelypo in ted

,directed forwards , and suban terior in p osition . The body

is n early flat an d well marked o ff from the n arrow elon gateddepressed p osterior ear, which reaches about half- way down theposterior margin . The an terior edge o f the Shell is stron gly archedforwards below the very small pro j ectin g an terior ear

,which seems

1 De Kon in ck,op . cit . , p . 182, p l . xxxix , fig . 8 .

2 Phil lip s, Pa loeoz . Foss . Cornw. Dev. , 184 1 , pp .

'

44—5 , p l . xx , fig s .

3 Dien er, Perm . Foss . Cen tr. Himal , Palaeon t. In d. ser . xv,Hima l . Foss ,

vo l . i , p t . v, 1903, p . 138 .

1 Whe e lton Hin d, op . cit. , p . 31 , p l . vi , fig s . 6—9 .

5 Von Koen en , Ncues Jahrb. f. M in . Geo l . , 1879 , p . 329 , t . vi , figs . 3, 4 .

1 20 Hen ry Bury- Escarpmen ts an d Tran sverse Rivers .

to have a deep byssal n o tch below it . The p o sterior margin of thep osterior ear meets the hin ge - 1in e at a very obtuse an gle . Thesurface of the body has a few stro n g , but low,

co n cen tric undulatio n sand fin er con cen tric lin es . Wheelto n Hin d 1

con sidersVon Ko en en ’

s

sp ecies to be iden tical with Salter’s Avicul0p ecten fibri llosus , whichhe puts in the genus Pseudamusium. Ps . auriculaturn (McCoy )

2

may also be compared .

Aviculop ecten cf. den sistria (Sandberger) . (P1. 11, Fig .

The right valve o f a small pectin iform shell, of which the Impression

an d extern al cast are preserved,i s practically indistinguishable

from the Culm sp ecies described and figured by Von Ko en ens

as Pecten den sistria Sandberger.

4Our sp ecimen has a height of

about 6 mm . and a width of about 5 mm .

Actin op teria sp .

The impression of the left valve o f a small shell,about 9 5 mm . in

len gth, app ears to belon g to the genus Actin op teria or Pteron ites .

In gen eral shape, p osition o f beak, size o f pre—umbon al p ortion ,

hin ge~lin e

,an d convexity of body , it resembles the Scotch species,

Pteron ites fluctuosus Etheridge,5 which Hin d 6refers to the genus

ActinOp teria, but the orn amen tation is rather differen t, con

sistin g in our sp ecimen o f numerous very fin e , equidistan t, regularradiatin g lin es, mo re“ closely p laced on the flatten ed p osterior halfo f the shell behind the body , on which con cen tric growth - lin es arealso presen t .

(To be con tin ued . )

Escarpm e n ts an d Tran sve rse Rive rs.

By HENRY BURY , M.A .

,

AT the end of a valuable paper o n the Sup erficial dep osits to then orth an d n orth west o f London

,Mr . Barrow 7

puts forwardcertain views as to the o rigin of escarpmen ts an d tran sverse riversin the Chiltern Hills an d the Weald which can hardly be allowed

'

to pass un challen ged by those in terested in the progress of ge o

morpho logy ,for un less there is more eviden ce in theirfavour than has

yet been p roduced these views are n o t progressive , but distin ctlyreaction ary . To sum up the p osition in his own words (op , cit .

,

p . 47) Lo n g after the cessation of all the ben din g movemen ts1 Whe e lton Hin d, op . cit. , vo l . ii , 1903, p . 106, p l . xvi , figs . 16—22 .

2 Ibid . , p . 108 , p l . xvi , figs . 23—7 .

3 Von Ko en en , op . cit . , p . 327, t . vi , fig . 2 .

4 San dberge r, Rhein Schichtsyst. Nassau, p . 296 , t . xxx , fig . 12 .

Etheridge , GEOL . MAG . , Vo l . X , 1873, p . 345 , P1. XII, Fig . 1 .

6 Whe e lton Hin d, op . cit , p . 25, p l . V , fig s . 8—12 .

7 Pro c . Ge o l . Assoc. , vol . xxx, 19 19 , pp . 1—48 .

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1 22 Hen ry Bury— Escarpmen ts an d Tran sverse Rivers .

an d fo rmed the bo ttom of a shallow sea,which passed through the

gap s, breakin g the Chalk escarpmen t up in to a series o f islan ds .

”

No eviden ce is o ffered that the sea ever reached the fo o t Of theescarpmen t at all ; an d even if such eviden ce were p roduced,

weshould still ask for pro of that it was the sea which fo rmed the gaps,and n ot the gaps (as drown ed river valleys) which admitted thesea . But it is as an exp lan ation o f the tran sferen ce of quartz p ebblesfrom the Lower Green sand to the Chalk that the hyp o thesis seems

to have been framed,an d here the in terpo lation of a n arrow arm of

the sea between the two lin es o f strata would seem to be rathera hin dran ce than a help to such migration ,

an d it is submitted thatun less very stron g reason s again st it can be given ,

the hyp o thesiso f tran sferen ce by tran sverse rivers is both simp ler andmore efficien t .No less un satisfactory is the accoun t given of the origin of thetran sverse rivers themselves . We are to ld that 1 When the elevationabove sea - level ” (of the sea - bo ttom in theGault) “ to ok p lace localstreams would tend to fo rm

,flowin g through all the gaps But

this is by n o mean s obvious . It has been held that the absen ce oflo n gitudin al rivers run n in g di rectly to the sea from the Weald iseviden ce again st the marin e o rigin o f the escarpmen ts an d riversystem o f that region ; an d similarly here we might exp ect that,if the sea en tered from the east alo n g the lin es of weak strata

,

it would retreat in the same direction,thereby givin g rise at on ce to

a lon gitudin al drain age .It must n ot be supposed that a subaerial origin for the win dgap s

i s in con sisten t with an y in fluen ce o f the ‘

sea in determin in g thedrain age system o f the So '

uth - East o f England . On the con trary ,it

leaves un touched the question whether that system origin ated on

an up lifted marin e plain ; an d it is by n o mean s opp o sed to thep ossibility that the sea,

whi ch seems at o n e time to have filled the .Lon don Basin , may , durin g p eriods o f temporary depression ,

havemade its way alon g the fo o t o f the escarpmen ts, as it seems to havedon e through the drown ed valleys o f the South Down s in Pleistocen etimes .

Nor must I be thought to wish in an y way to depreciate the valueo f Mr . Barrow’

s work . It is o n ly to some o f his theoretical viewsthat I take excep tion ,

because they appear to me retrogressiveand un supported by the facts so far before us . If there are o therfacts n ecessitatin g a radical chan ge o f view, it is to be hoped that theywill so on be published .

1 Op . cit. , p . 40

A . Bramma l l— Some Mi cr ochem i ca l Methods . 1 23

Som e M icro chem ical Me tho ds.

By ALFRED BRAMMALL,B .Sc . F.GS .

, Imperial Co llege o f

Scien ce an d Techn o lo gy , South Ken sin gton

THEwell - kn own an d highly sen sitive tests afforded by ferricyan ide ,ferro cyan ide, and thiocyan ate so lution s for the detectio n o f

iron may be adap ted, at the co st of a little trouble , to the microchemi cal investigation of certain rocks in thin sectio n

,as can also

the equally well - kn own fusion test for man gan ese . The fo llowin gmethods have proved useful in sp ecial circumstan ces of the n aturei ndicated in each case .1 . The n ecessity arose to determin e the di stribution o f hydrated

f erric matter in sedimen ts affected by low-

grade metamorphism,

and to detect an y marked tenden cy towards the accumulation o f

this substan ce in an d about foci of recrystallization . Method applied“

to rock slices : The cover -

glass havin g been removed,the Slice is

first clean sed o f balsam,then p o lished, again clean sed, an d warmed

to evap orate an y sp irit retain ed by capillarity . Meanwhile, reactionpapers are prepared : a piece o f white drawin g -

pap er, o f area abouttwice that o f the ro ck slice, is soaked in stron g HCl and pressedbetween sheets of similar paper un til it is n o lon ger wet an

ammon ium thiocyan ate pap er is prepared in a similar way . Thea cid paper is careful ly laid upon the slice an d covered with a stripo f cardboard .o n which is laid a hot iron (2—3 lb . weight), care bein gtaken n ot to shear the slice . After two o r three minutes the weight,c ardboard

,and pap er are carefully lifted from the Slice, which is

a llowed to dry ; the thio cyan ate pap er is app lied (the same prec aution s bein g observed) and p ressed, in the co ld, to en sure go odcon tact with the slice for a few minutes ; it is then removed an d

' thes lice i s again thoroughly dried before bein g examin ed In tran smi ttedlight . The di stribution o f ferric iron i s revealed by a tran sparen tbl -o od red stain of Fe(CNS)Po tassium ferro cyan ide may be substitiIted for the thio cyan ate ,

but the blue co loration produced is due to an opaque pigmen t ,which must be exami n ed in reflected light . The thio cyan ate stainhas the advan tage of tran sparen cy .

(a) The method has proved of esp ecial value in the examin atio nof Sp o tted ro cks a typ ical case is described : In a Kn o tenschiefer from Andlauthal , Vo sges, the spo ts, con sp icuous en oughin hand Specimen s

, are differen tiated from the matrix in thi nsection on ly by the fo llowin g features : (i) abundan t in clusion s o f

opacite (carbo n ,largely ) ; the in clusion s in some Sp o ts traversed

by p igmen t - rich beddin g p lan es app ear to have been derived, inpart, from these p lan es, which are relatively free from this opaque“matter for a short distan ce on each side o f the sp o t (ii) an irregular,brown ish

,tran sparen t stain formin g a p eripheral zon e (iii)

p o larization co lours sen sibly lower than tho se of. the matrix somes p o ts _

may be almost iso tropic . On microchemical treatmen t the

1 24 A . Bramma l l— Some Mi crbchemi ca l Methods .

Sp o ts y ield a pron ounced stain ,while the matrix takes on ly a feeble

stain o n the who le the p eripheral zo n e is somewhat less resp on siveto treatmen t than the rest - Of the sp o t, but ultimately is stain edthroughout .(b) The dark in clusio n s in chiasto lite (andalusite) react very feebly ,

but the n arrow opaque zon e of matrix immediately surroundin gthe crystals usually reacts very stron gly . The stain s on the

thiocyan ate pap er itself are worth examin ation .

(0 ) The alteration o f chiasto lite (an dalusite) , y ieldin g structuresclosely resemblin g tho se observed in o livin e alterin g to serp en tin e,often invo lves p ermeation o f the min eral by iron - rich water impregn atin g the matrix the chan n els o f alteratio n an d their dust—filleddilatio n s then react stron gly for iron .

(d) Lamin ation in Shales is frequen tly emphasized by'

n arrowban ds rich in opaque (carbon aceous) matter these layers are alsousually rich in some e asily so luble comp oun d of

“ferric iro n

a feature which may be, in part, at least, origin al, an d possibly dueto the in compatibility o f iron with co llo idal organ ic matte r inso lution

,the two substan ces bein g precip itated to gether .

(e ) Magn etite bein g much more easily so luble in HCl than ilmen ite:(or titan oferrite ) , it reacts much more readily by this test thando es the latter . The reaction pap ers i n this case should be preparedfrom blo ttin g - pap er, an d should be slightly wet so that thethio cyan ate stain may spread somewhat by capillarity ; the stainon the thio cyan ate pap er itself should n o t be disregarded .

The rare o ccurren ce of grain s o f n ative iro n in certain ro cks ismore readily detected by app ly in g a wash o f slightly acidulated.

CuSO,so lution

,which coats the iro n with a film o f metallic copper,

recogn izable in reflected light .(f) The method is also useful for demo n stratin g the distribution of

chalybite in o o litic iron ston es an d less ferrugin ous o o lites . Althoughchalybite is disso lved readily by HCl in the co ld,

the weight usedto press down the acid reaction pap er up on the ro ck slice should behot so that the hydrated ferrous chloride first formed may

-be themore' rap idly o xidized to the basic ferric chloride ; the acid is insuffi cien t excess to con vert some o f this basic comp oun d to the n ormalferric Salt . As the products of reaction with HCl are hydrates .

an d very hygroscop ic, the app lication o f the thio cyan ate paperten ds [ to produce smearin g ; this is largely preven ted by usin greaction p ap erswhich are n o t wet by dry in g the preparationin a ho t atmo sphere o r a desiccator after each reaction ,

an d byexamin ing the preparation without delay .

It is well to supp lemen t the thio cyan ate preparation by two

o thers,usin g p o tassium ferricyan ide and p o tassium ferro cyan ide

o n separate slices ; the blue p igmen t produced is examin ed byreflected light . The deliquescen t CaCl2 may be removed by firstthoroughly dry in g the preparation (so as to cake the p i gmen t)and then carefully washin g it— the p igmen t remain in g fixed .

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1 26 James Gr oves— A Cu r i ou s Fossi l Char op hy te Fru i t.

A Curi o us Fo ssil Charo phy te Fruit.

By JAMES GROVES .

HROUGH the ki n dn esst

o f Mr . Hen ry Wo ods, I have had theopp ortun ity o f examin in g three blo cks o f limeston e belon gin g

to the Sedgwick Museum at Cambridge , which were co llected bythe late E . B . Tawn ey ,

from the Chara Bed Etage Oen in gien ,

Upp er Mio cen e, at Lo cle , Jura (Can ton Neuc'

hate l , Switzerlan d) .The blo cks co n tain a n umber - o f the remain s o f fruits of a sp ecieso f Oharophyte , which presen t a feature I had n ot hitherto observed,

an d to which I thin k atten tion may advan tageously be drawn .

Before describin g this p eculiarity ,however

,it will be desirable

to say somethin g as to the con dition s o f preservation in whichsuch bodies . are usually foun d .

In livin g species o f Chum ,Lamp rothamuium,

Lychn otkamuus,Nite llop sis , an d To lyp e lla ,

when the fruits are more o r less mature ,the five sp iral c—ells which fo rm the sac of the o ogo n ium o ften secretea dep osit o f lime extremely fin e an d clo se—grain ed,

almo st p orcelainlike in texture . The lime is gradually dep o sited o n the in n er wallo f each sp iral - cell , that 1s o n the side adjacen t to the o o sp ore , ofteno n ly partially ,

but_

in its fullest developmen t almo st ‘ en tirely ,

rep lacin g the o riginal pro top lasmic co n ten ts of the cell . The limecon ten ts o f the five sp iral - cells combin e to form a firm hard shel l ,kn own as the l ime - shell , whi ch envelopes the o o sp o re , and is n o

doubt pro tective in character . When the fruit becomes dry an d the

soft part co llap ses, if the lime dep o sit is thin ,each o f the sp iral

cells app ears as a roun ded furrow . The co n cavity of the cel lsdecreases “

in prop ortion as the lime dep osit thicken s, becomin gflat or even convex when the cell is comp letely fil led . Neitherthe five cells formin g the coronula n or the sin gle stalk - cellsecrete lime .Apparen tly in almo st all cases it is to the presen ce o f such a lime

shell that we owe the preservatio n o f charophyte fruits as fossils,an d it is n o ticeable that the o n e livin g gen us, Nitella, which do esn o t produce _

a lime - shell,is n otkn own in the fo ssil state . The remain s

o f charophy te fruits, ordin arily foun d as fo ssils,con sist o f the sac

fo rmed by the five sp iral cells o n ly ,without e ither the coronula

o r the fo o t stalk, an d therefore corresp on d with the lime shell .Occasion ally the o o sp ores are found l n the sacs . We fin d the sp iralcells l n the fo ssils i n all stages o f thickn ess

,ran gin g from the very

thin con cave ban ds i n some typ es, which I refer to To lup e lla ,to the

thick convex co ils foun d l n some sp ecimen s of the Chum medicaqiuulatyp e .On the in terior surface o f some o f the fo ssil o ogon ium sacs o n e

comes acro ss a lay er of so ft fin e white lime of vary in g thickn ess ,but usually much thin n er than the hard darker outer shell . In thesp ecimen s o f which I am writin g it is in this in n er lay er o f white

Jamcs Gr oves— A Cur i ous Fossi l Oharop hy te Fru i t. 1 27

lime that the unusual feature o ccurs in the shap e o f a tubul arho llow, which fo llows the course o f each o f the sp iral - cells, as shownin Fig . 1 , B, C

’. I had previously assumed that the lay er o f white lime

was simply a dep osit, extran eous in origin ,which had taken p lace

between the o ogo n ium sac an d the p o ssibly shrun ken o o sp ore .The presen ce of these un ifo rm tubular“ ho llows in Mr . Tawn ey ’

s

sp ecimen s, and the division of the white lin e in to regular bands ,as shown in the illustration

,however

,seems to po in t to an organ ic

origi n .

FIG . l .

—Fruit o f fossil Charophyte from Locle , Switzerlan d . A . Nearly e n tireo ogon ium ,

x circa 31 . B . Broke n sp ecimen , showin g sectio n of part o f

the wal l o f the o ogon ium an d an in tern al lay er o f so ft white l ime withtubular chan n e l s , X

'

circa 31 . C . Tran sverse section (diagrammatic o f

thre e of the p etrified spiral ce l l s formin g the wal l o f the o ogon ium) ,a a with the corre spon din g ban ds o f the white l ime lay er , b 6 havin gcompre ssed tubular chan n e ls shown as black ovals , x circa 65 .

I am at presen t un able to suggest an y exp lan ation of thisproblematic feature , an d the main obj ect o f this n o te is to drawatten tio n to its o ccurren ce , in the hop e that those havin g theopportun ity of investigatin g freshwater depo sits will keep a lo okout for charophyte

'

fruits,which may throw some light on the

developmen t in question .

I have n ot seen authen tic sp ecimen s of Chara Meriauii Braun,

which is rep orted from the Miocen e of Switzerlan d an d Baden ,

but co n clude from Heer’s figures in Flora Tertiaria Helveti ce thatthe specimen s under con sideration belon g to that sp ecies .

REVIEWS.

EQUIDzE o r THE OLIGOCENE, MIOCENE,AND PLIOCENE o r NORTH

AMERICA . ICONOGRAPHIC TYPE REv1s10 N . By H. F . OSBORN .

‘

Memo irs o f the American Museum o f Natural History ,New

Series , Vo l . II , Pt . I,1918 .

-

.pp 217, with 54 plates an d 173

text figures .

HE wo rk issued un der the fo rego in g title 1s a systematic revisio nof the hun dred an d forty six described sp eci es of Oligocen e—4

Pliocen e horses of North America,with rep roduction s o f the

o rigin al figures, n ew figures o f man y typ es , and a series o f p latesof comparative drawin gs . It is in ten ded to clear the groun d fo rPresiden t Osborn ’

s lo n g - lo oked for mon ograph of the Equidaeand is in ten tio n ally restricted to statemen ts o f fact wi th o n ly thatirreducible mi n imum o f theoretical con clusion s essen tial in sucha work .

In the Op in ion o f the revi ewer it is the most impressive palaeon tol ogical work which has ever been published . The short abso lutelyclear, an d workable gen eric and sp ecific diagn o ses, the simp le andstraightforward arran gemen t , the extreme lucidity o f the com

parative drawin gs, the abun dan ce , p erfectio n ,and accurate datin g

o f the material,in evitably leave the reader with an overwhelmin g

feelin g that here the mode o f mammalian evo lution i s shown i n

d etailb

for the first time,and

“

shown in the best p o ssible way bya rran gin g the facts in order an d leavin g them to sp eak forthemselves .

When the fin al mon o graph is published, with Presiden t Osborn ’

s

critical in terpretatio n s o f the differen t phy la within each genus ,an d of the evo lutio n o f each part co n sidered in detail by itself.and in correlatio n with the rest o f the structure

,we shall have the

m o st adequate material which_

can at presen t be made available fora critical discussion o f bio logical theo ries o f evo lution .

Palaeon to logists an d zo o logists have been lon g acquain ted withthe series o f gen eric stages leadin g up to Equus, as they have beene stablished by the American palaeo n to logists but n on e excep t tho sewho have been so fo rtun ate as to se e the American Museum co lleetion s can have had an y co n cep tion o f the comp leten ess o f the sto ry ,

an d even tho se who have h an dled that vast series could n ot

previously appreciate the in fin itely clo se gradation between thesp ecies o f a sin gle genus which o ccur at differen t horizo n s .

As the importan ce o f palaeo n to logical material dep ends en tirelyo n the fact that the relative ages o f the sp ecies formin g a seriesare kn own

,Presiden t Osbo rn begin s his mon ograph with a most

useful accoun t o f the stratigraphy and correlation of the man ylo calities o f North America which y ield ho rse remain s . The who leseries o f North American Tertiary lan d deposits is n ow dividedin to zon es on mammal eviden ce , and some p rogress has been made

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1 30 Revi ews — The Gr ima lcl i Ca vern s.

No n e but tho se who have handled similar material can have anyidea of the vast amoun t o f work o f the highest class con cealed behin dthe un preten tiousn ess o f this sup erb mo n ograph . Presiden t Osbornexpresses his ackn owledgmen ts to his co lleagues, Gidley , Grang er,and Matthew, to the published wo rk o f man y o ther Americanp alaeon to logists, to Pro fesso r J . C. Merriam,

tO his assistan t ,Miss Ripley ,

and to the artists, Messrs . Oka an d Yoshihara,an d

Mrs . Stirlin g .

This memo ir represen ts the result o f team work by emin en tstuden ts fused in to o n e by that palaeon to logist whose studies havegradually established tho se philo sophical prin cip les o n whichmodern methods o f palaeo n to logical in vestigation very largelydep en d . It provides a triumphan t vindication ,

had on e beenn ecessary , o f the soun dn ess of the p o licy adopted by Pro fesso rOsborn o f sen din g out o n co llectin g exp editio n s y ear after y earthose palaeon to logists who are go in g to work up the materialacquired . On ly in this way is it p o ssible to attain that certain tyo f horizon which is essen tial fo r satisfactory work . Had dep en den cebeen p laced on the purchase o f co llection s an d o n the sp o radicgatherin gs o f geo logists , this wo rk would have forever remain edimp ossible , because the zon al classification , p robably the mo stdetailed an d satisfacto ry on e kn own , . could n ot have been workedout an d the horizon of an y sp ecimen would always have been op ento doubt .

D . M. S. WATSON .

THE GRIMALDI CAVERNs .

LEs GROTTEs DE GRIMALDI (BAoussE- RoussE) . Tome I , Fasc . IV :

Géo lo gie et Paléon to logie'

(flu ) . By MARCELLIN BOULE .

pp . 237—362, p ls . xxx—xli . Mo n aco , 1919 .

PROFESSOR BOULE is to

_

be co n gratulated o n the comp letio nof his imp ortan t work o n the remain s of vertebrate an imals

found with man in the cavern s o f Grimaldi on the south coast o fFran ce . It is n ot merely a techn ical treatise on fossil bon es an d

teeth,but also a gen eral discussion o f the Pleisto cen e mammalian

faun a, of very wide in terest . The fin al in stalmen t deals with the

Carn ivora,In sectivo ra,

Cheirop tera ,and Roden tia , besides mo re

fragmen tary remain s of birds, rep tiles, and amphibian s . It thenends with a summary of the results .

Professor Boule po in ts out that the succession of a warm fauna(Elep has autiquus, Rhin oceros merclci , Hipp op otamus, a co ldfaun a (glutton ,

ermin e , marmo t , rein deer, and then the modernfaun a, is as clear in the low latitude o f the Fren ch Riviera as in therest o f Cen tral and Western Europ e . He correlates the first (o rChellean ) p eriod with the third in terglacial p eriod o f Ben ck, an d

the fo llowin g (o r Mousterian ) p eriod with . the Wiirmlan glac1al

ep isode o f Ben ck . He adds map s showmg the geograph1cal

Revla va— Cr etaceous Si l i ci sp oug i ce . 1 8 1

distribution o f some o f the most imp ortan t sp ecies of mammals ,an d in several cases he illustrates the relation ship s of the Pleisto cen eforms by elaborate gen ealog ical tables . His observation s o n thelyn x are esp ecially in terestin g , for he shows that the extin ct raceo f Grimaldi 1s precisely in termediate between the existin g n orthernrace an d that still foun d In Spain .

THE SCHRAMMEN COLLECTION OF CRETACEOUS SILICISPONGUE IN

THE AMERICAN MUSEUM OF NATURAL HISTORY . By Dr .

MARJORIE O’

CONNELL . Bull . American Mus . Nat . Hist ,

vo l . xli,1919 . pp . 261 , with 14 plates .

THE palaeon to logist so on learn s to divide n ewly published matterin to two categories , that which gives more trouble than the

in formation o ffered is worth,an d that which

,by savin g the '

reade r

trouble, aids him in acquirin g the n ew kn owledge it has to impart .A glan ce at the “work un der review leaves n o doubt in which categoryit Shoul d be placed While the“amoun t o f n ew in formation it con tain smay n ot be great, it is n ot likely that an yo n e wishin g to gain a

gen eral kn owledge o f Cretaceous Sp on ges will con sult this work invain ,

o r, havin g read i t,will put it down without un derstan din g

how far our presen t kn owledge of the subj ect go es, or withoutkn owin g what works to co n sult for further in formation .

But he will have learn t more than this . The trouble he IS savedis the clearin g away o f un n ecessary obstacles to kn owledge , an d n ot

the trouble of takin g pain s . A glan ce at pp . 341—46 shows the ordealto be undergon e before y ou or I can become a go od discip le o fPalaeosp on gio lo gy (a blessed word,

but a mealy mouthful) .The termin o logy o f sp icules is a laceratin g tan gle o f Amphitorn s ,Cricamphityles, Dian cistras , an d such like , from which on e emergeso n ly to come upon Ophirhabds lo n g , smoo th mon axo n s o f

irregular o r sn ake - like curvature , gen erally taperin g towardsbo th en ds with but a Tox bow- Shap ed sp icule an d a Labid

spicule shap ed like sugar ton gs for self- defen ce— and there are.

mo re than a hundred o f these thorn y terms . But havin g masteredthe sp icular termin o lo gy an d learn ed how to apply it— here is thetest o f its utility— the studen t o f fo ssil Sp on ges may feel wellequipp ed for further study ,

and may reason ably hop e that thedifficulties of the future will be con siderably less than tho se alreadyovercome . As a studen t, the comp lex termi n o logy o f typ es (pp . 99

fo llowin g clo sely that Of Schuchert an d Buckman,but

in ciden tally con cern s him— this is main ly the curator’s care ;

but he will welcome the detailed accoun t of the Europ ean Cretaceousformation s and the earth history o f that ep o ch in Europ e (pp . 47

97 ) fin din g here the mean s o f correlatin g lo cal termin o logy withstratigraphical terms o f wider mean in g . This

,with a useful

historical résumé o f wo rk on Spon ges as a group ,a geographical

analysis o f the literature .o f Cretaceous Sp o n ges, a detailed systema tic

132 Reviews —Cr eta ceous S ili ci sp oug iw.

descrip tio n o f the Schrammen Co llection in the American Museumo f Natural History ,

and a biblio graphy o f over two hundred wo rks,

fin ishes what is n ot merely an accoun t o f the Schrammen Co llectio nin America

,but much more , a very comp lete in troductio n to the

study o f Cretaceous Spon ges as a who le .It is hardly a just cause fo r complain t that the authoress’s

n ation ality app ears in her writin g . NO En glishman who loves hislan d would refer, in sp eakin g o f the Dover'

district,to the n earby

cliffs'

alo n g the Ken tish coast,(p . Arko sic (p . 81 ) is a

stran ge wo rd and Cretacic however defen sible,is bo th stran ge

an d ugly ,and do es n o t app ear to be used in an y sen se difieren t

from the familiar Cretaceous un less it is that Cretacic is

American Cretaceous ; for Cretaceo us is used,e .g . on pp . 52

and 84, as well as in the title o f the pap er . Discon formablyfor Un con formably is un familiar . The fo llowin g misprin tshave been n o ticed : Morven (p . 62) apparen tly should beMo rvan o n p . 72 n o rthern is evidentlv a misprin t forsouthern on p . 9 1 corn ea should be car

-

nea an d o n

p . 154 Acorckora’ori ia should be Acrockorclon ia On pp . 150,

188, etc .

,Callop egma acauli s is written for C. ac

'

aule

Sin ce the bo ok under review is o sten sibly a work o n Spo n gesthis is hardly the p lace to criticize in detail the stratigraphyexp ounded o n pp . 47—97 . But this o therwise admirable re sumeis somewhat marred

_

by the fundamen tal misun derstan din g o f

the " zo n e ’

,apparen t gen erally ,

but exp licit in the remark (o . 52)'

as in all such faun al wo rk , the cephalo p ods bein g p elagi c, are

con sidered the mo st reliable In the establishin g o f zo n es o f limitedvertical , but wide ho rizon tal exten t, for which reason .the standardzon al subdivision s o f the Cretaceous are based up on theAmmon ites ”

. Now, if I read its founder,Opp el , rightly; the

zon e is that sedimen t (if an y ) which was dep o sited durin g a'

given time in the earth’s history . Fo r co nven ien ce,it is n amed

after “

a fo ssil o ccurrin g in it (n ot n ecessarily throughout it) in on e

locality (almost n ecessarily n ot all over the world) . How,then

,can

a zon e be referred to relatively as o f wide ho rizo n tal exten t ”

when a zon e is n ecessarily worldwide ? An d how can zo n alsubdivisio n s be based up o n Ammon ites when o n ly their n amesare based up on fo ssils (It may also be remarked that to imp lythat Ammon ites were p elagi c is an assump tion ,

even if it is gen erallytrue that o ther Cephalo p ods are an d were . )The autho ress also app ears to think that the zon e o f Pecten asp er

In the South West o f En glan d is usually in cluded in the Albianrather than In the Cen oman ian

,for o n p . 57 she writes : I shall

in clude therein [in the Cen oman ian ] the Warmin ster faun a o f thePecteu asp er zon e, Sin ce it would o therwise be difficult to comparewith“ the figures fo r en tire faun as o n the Con tin en t

,where the

1 The di vision ,by Gro ssoeuvre _Oi the Chalk in to zon e s n amed afterAmmon ites

is g iven in tabular fo rm , with corre latio n s , o n p . 50 .

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134 Revi ews— Magn eti c Di stu rban ces .

examin ation, o n e ly in g between Melton Mowbray an d Nottin gham,

an d the o ther in the iron sto n e district o f Irthlin gborough .

Additio n al_

magn e tic observatio n s were carried out by Mr . “Talker,

an d Dr . Co x was commission ed to make a geo logical and p etro lo gicalstudy o f the two areas an d to discuss the results, a duty which hehas accomp lished with much skill an d judgmen t .The problem is quite differen t from that p resen ted by the much

greater magn etic disturban ces in the Western Isles o f Scotland,

which are man ifestly due to perman en t magn etization o f ro cks at

the - surface . Here,o n the o ther hand

,we have to do with induced

magn etism,and Mr . Walker’s observatio n s in dicate that the seat

Of the disturban ce in Northampto n shire is at a depth of n o t lessthan feet . The in feren ce is that ro cks o f n o teworthy magn eticsuscep tibility are in p lace at some considerable dep th ben eath thisarea

,and that there is '

some irregularity in their distribution .

Discussion o f undergroun d geo logy n ecessarily in vo lves an elemen to f the hyp othetical but the author is able to muster '

a sufficien tn umber “

o f -data'

bearin g o n the question . He has made a li st o fall the rocks which are likely to o ccur ben eath the district , an d

examin ed their p etrographical characters,while determin atio n s

o f magn etic suscep tibility have been furn ished. by Pro fessor ErnestWilso n . Dr . Co x p o in ts out that this prop erty in differen t ro cks

closely correlated with their con ten t o f magn etite . A gran itecon tain in g o n ly a little magn etite has a much higher susceptibilitythan a basic ro ck rich in iro n in the fo rm Of silicates an d in ilmen ite .

The autho r ascribes the disturban ces to the presen ce o f do leritesas in trusion s in the subjace

'

n t Coal - measures . Such do lerites are

well - kn own in o ther p arts o f the Midlan ds, and they p o ssess a highermagn etic suscep tibility than an y o ther rOckS in that region . It maybe men tio n ed that the investigatio n was un dertaken primarilyin the hop e of detectin g con cealed iro n - ores in this way ,

an d thep ossibility Should certain ly be kep t in VIew in r elatio n to likemagn etic disturban ces elsewhere . Such cases as that o f the Ro sedaleo re in Cleveland Show that an iso lated body o f bedded magn etitero ck may o ccur in the midst o f a fo rmatio n which elsewhere carrieso n ly iron - oxides and carbon ate . We have, however, n o groun ds

fo r co n j ecturin g such an o ccurren ce ben eath Northamp to n shire ,and in trusive do lerites seem to afford at least a good provisionalexp lanatio n Of the facts . The in ferred irregularity o f theirdistribution is attributed to faultin g , an d the autho r shows that theObserved magn etic disturban ces in this area corresp o nd clo selywith fau lts which are mapp ed in the Meso zo ic strata ,

an d almo stcertain ly exten d in to the un derly in g Palaeo zo ic ro cks . Thedisturbances n ear Irthlin gbo rough can be referred “

to the Jurass1ciron - Ores o f the district, which pass from ferrous carbo n ate in thein terio r in to hydrated ferric oxide at the weathered outcrop ,

WIth

a co nsequent dimin ution in magn etic suscep tibility .

REPORTS AND PROCEEDINGS.

GEOLOGICAL SOCIETY OF LONDON .

December 17, 1919— Mr . G. W . Lamplugh, Presiden t

,in

the chair .

In the absen ce o f the author,the fo llowin g pap er was read by

Mr . R . D . Oldham, A Rift - Valley in WesternPersia . By Professor S. James Shan d,

D .Sc .

,F.GS .

Asmari Moun tain , n ear the o ilfie lds of Maidan - i - Naftun,in the

Bakhtiari coun try o f Western Pe rsia ,is an in lier of Oligo cen e

limesto n e amon g the beds o f the Fars System (Mio cen e) , the lattercon sistin g , in the lower part, o f bedded gyp sum with in tercalatedShales and a few thin limesto n es . The moun tain is a whale - back ,16 miles lon g and 3 miles wide at the middle, formed by a simp lesy mmetrical an ticlin e plun gin g at bo th ends . The n orth - westerne nd p lun ges rather steeply ,

an d Shows '

n o abn o rmal structures ;but at the south - eastern e n d the fo ld has co llapsed alon g its len gthfor a distan ce o f 3 miles, lettin g the gyp sum beds down in to a

trough _

in the limeston e .This trough is boun ded by two main faults hadin g n o rth

e astwards an d south - eastwards resp ectively ,with an average hade

o f an d marked by steep escarpmen ts . The n orthern scarpwhich lies p ractically alon g the axis o f the an ticlin e , is at o n e p o in t500 feet high but the southern on e

,bein g low down ‘

o n the flan kOf the an ticlin e, is much less co n spicuous . Besides these main faultsthere are at least three o ther big faults parallel to them, _

which produce min or scarp s within the valley the valley - flo or thus descen dsin terraces towards the south west

,beside s havin g a gen eral south

e astward in clin ation of some Uphill,

.towards the crest o f themoun tain ,

the down throw o f the limitin g faults dimin isfhes graduallyto zero and the valley dies out o n the broad top o f the an ticlin e .DownhIll

'

, towards the p lun gin g n ose o f the an ticlin e,the trough

is closed abruptly by a cro ss - fault n early at right an gles to thean ticlin al axis . The len gth o f the who le trough is 2—é miles , and itswidth half a mile .The n orthern boun dary - fault at its maximum has a down throw

o f about 500 feet , the parallel faults ran ge from 150 to 200 feet,and the cross - fault throws about 100 feet .The gypsiferous beds which o n ce completely filled the trough haVebeen partly removed by erosion clearly revealin g the fault—wallsin the lower part of . the valley . These fault—scarps in their lowerp ort-ion s are remarkably fresh , an d Show the smo othed an d flutedsurfaces produced by the friction o f the slidin g faces .

The drain age o f the faulted region is curious in several resp ects .

The o n ly p eren n ial stream that traverses the\

valley cuts Sheeracross it from side to side . Risin g in the gyp sum beds on the

n orth - eastern flan k o f the an ticlin e,the stream turn s south

136 Rep orts (if: Procee'

di n gs—f Geo l

'

og ica l Society of Lo n don .

westwards , and cuts right through the limesto n e in a deep cano n

the latter breaches the n orthern fault - scarp where the down throwis greatest, and from here the bed o f the stream lies in the gyp sumo f the valley bo ttom, excep t fo r a short stretch between two faul ts,where the limeston e flo or is again exposed to view . The streamfin ally breaks through the southern limesto n e wall , an d so makesits escap e from the valley .

These condition s imp ly' that the river assumed approximately

its presen t direction when there was a cover o f gypsiferous beds overthe who le area,

an d that although y oun ger than the in itiatio no f the faultin g , it is o lder than the sculp turin g o f the in side of thefault - trough . The eastern e nd o f the trough is again tapp ed byan o ther an d smaller stream with a precisely Similar developmen t .It might be surmised from the excellen t preservation o f the

fluted surfaces o n the fault—scarp s that the last movemen t to okp lace at a very recen t date

,but the behaviour of the river in crossin g

the scarps do es n ot favour this supp o sitio n . The successIOn of

even ts app ears to have been as fo llows(1 ) Fo rmation o f the trough with gyp sum - in fillin g by p artial col lap se o f

the an ticlin e .

(2 ) Leve llin g o f the gy p sum surface an d deve lopme n t o f a stream acro ss

_

the p osition . of the buri ed trough .

(3) The stream, cuttin g down through gyp sum, discovers the,

faults;

etche s them out, deve lop s subseque n ts alon g them,an d thus

gradual ly e ats out the gy p sum fil lin g the rift, until the'

p re sen t

top ography results .

January 7,1920 .

— Mr . G. W. Lamp lugh , Presiden t, inthe chair .

1 . On Syringotkyris Winchell and certain Carbon iferousBrachiopoda referred to Sp iriferin a D

’

Orbign y .

”

By FrederickJohn North, B .Sc. ,

F.G S.

This pap er is the outcome o f a suggestion made in 19 13 byProfessor T . F . Sibly , who p o in ted out the desirability of an attemptto remove the un certain ty whi ch had hitherto existed in the n amin go f the British species o f Syring

'

otkyris, and o f the Carbon iferousSp iriferids possessin g a lamello se surface orn amen t, which it wascustomary to refer to Sp iriferin a because there was n o o ther genusfor their recep tion , although it had lon g been recogn ized that few,

if an y of them, really belon ged to that genus .

After in dicatin g the exact sen se in which certain frequen tlyo ccurrin g terms are used, and reviewin g the history of previousresearch; the author discusses the history in Avon ian times o f thegenus Syringotkyris, an d suggests a classification of its species .

Variation s'du

'

e to time, to en vironmen tal conditio n s, an d to

distribution in space, are recogn ized, and distin ctive n ames are givento the mutation s characteristic o f certain horizon s .

The syrin x (it is suggested) was a sp ecial arran gemen t calledin to existen ce to con tro l the direction of and to supp ort the

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138 Rep orts (63Pr oceedi n gs— Edi n burgh Geo log ical Soci ety .

l o calities are n ot so excep tion al as they app ear to be at first Sighta nd that En glish localities may be studied with advan tage, incomparison with and exp lan ation of. the features of these Con tin en tald ep o sits .

(7) It is foun d that the preserved strata of the GloucestershireWorcestershire Lias un der co n sideration happ en in the main to bedep osits of dates when the livin g Ammon ites were rather small ;while there is faun al failure and presumably stratal failure at thetimes when large Ammon ites flourished . The converse phen om en aare main ly illustrated by North Somerset dep o sits .

(8) The times when large and small Ammon ites lived appear tofo llow on e an other like waves

,illustrated even in a Short table of

Liassic dep osits .

(9 ) AS a result of the investigation s - con n ected with this pap erit seems to be advisable, for recordin g purp oses at an y rate , to makefurther subdiv ision s in the scheme Set forth in the author’s formerpaper .

EDINBURGH GEOLOGICAL SOCIETY .

November 19, 1919 - Mr . E . B . Bailey , M.C. ,

B .A. ,F.GS . ,

Presiden t,

in the chair .

1 . No tice o f a Shrimp—bearin g Limesto n e in the CalciferousSandsto n e Series n ear Gran to n .

”

By D . Tait, H.M. Geo log icalSurvey .

This is a n ew fossiliferous lo cality ,which is exposed between tide

marks n ear Muirhouse , about midway between Cramond an d

Gran ton . The chief feature o f this bed lies in the remarkableabundan ce of fossil Shrimps which“ it con tain s, some o f which maybe n ew sp ecies . It is 18 in ches thick, but is n o t a so lid bed .

It is comp o sed o f thin bands of l imeston e with partin gs o f shale .It varies in thickn ess, and the in dividual bands, which are fin elylamin ated

,have minutely wrinkled surfaces and shrin kage cracks

due to dry in g .

What is p robably '

the same band is exposed 4 feet above thesandston e of Gran ton (Sea) Quarry ,

and again in Gran to n (Land)Quarry . The horizon o f this band is, therefore, low down in theGran ton Sandston e Series .

The fossils obtain ed from the limeston e to this date are Orthoceras,Nauti lus , Estheria, at least three Sp ecies o f shrimps, an d the fishesRhadin ichthys brevis Traq. an d Euryn otus cre natus Agassiz . Thefishes were determin ed by Dr . Smith Wo odward o f the BritishMuseum .

The litho logical descriptio n o f this bed at Gran ton , though itis p ecul iar, app lies exactly also to the well - kn own shrimp limeston eat Cheese Bay n ear Gullan e this an d the similarity o f their fo ssilco n ten ts tempts o n e to correlate them with each o ther . But

Dr . Peach says the Sp ecies o f shrimps found in the Gran ton Bed are

Rep or ts at Pr oceedi n gs— Edi n burgh Geo log i ca l Soci ety . 139

differen t from those found at Gullan e , an d the Gullan e Bed hasbeen p laced on the ho rizon o f theWardie Shales, while the Gran to nBed is certain ly in the Gran ton Sandsto n e Series inmediate ly below .

2 . No te on a Find OfMan gan ese Ore in Dalroy Burn ,a Tributary

o f the River. Nairn,In vern ess .

”

By Thomas Wallace,Invern ess .

Mr . Wallace gives a gen eral descrip tion o f the district,illustrated

by a map and section,showin g ,

the p osition s in which man gan eseo re was found . The chief locality is in the burn n ear the farm of

Dalroy . The ore is there found as a ban d o f p ossibly 3 feet inthickn ess

,ly in g immediately under the Old Red San dsto n e Con

glomerate , and restin g on the Gn eiss below . The ro ck con tain s30 p er cen t man gan ese oxide . Besides the ore in situ

,man y frag

men ts were found in the burn ,and also in the fields an d at Clara

Scho o lhouse to the west .3. Exhibition o f the Rhomb - Porphyry Boulder from Po rtsoy ,

Ban ffshire . ” By H. H. Read,H.M. Geo logical Survey “

This boulder of typical rhomb -

p orphyry was.

foun d between tidemarks in a cove about 50 yards west of Portsoy Gasworks . Fromthe directio n o f ice - flow in Ban ffshire it was con cluded that tran sportby Scan din avian ice was extremely un likely . The p o ssibility o f

tran sp ort by floatin g ice calved from the main Scan din avian icefron t, durin g a period in which a n arrow reach of Op en water laybetween the Scandin avian and Sco ttish ice - Sheets, was suggested ,

but the equal p o ssibility o f human tran sp o rt as ship ’

s ballastwas also admitted .

December 17,19 19 — Mr . E . B . Bailey , M.C.

,B .A .

,F .G.S

,Presiden t,

in the chair .

The Ayrshire Baux itic Clay . By G. V. Wilson ,B .Sc F.G.S.

The high refractory character o f the Ayrshire Bauxitic Clay was

discovered early in 19 16 . A samp le previously co llected by Mr . E . M.

Anderso n from the expo sure o n Saltcoats Shore had been an alysedwith the hop e that the rock might be a bauxite . The result of thisan alysis showed that the material was rich in alumin a, but main lyin a combin ed state, and so n ot available for use in the manufactureof alumin ium. On co n sideration ,

it seemed p ossible that a ro ckcon tain in g such a high ’

p ercen tage o f alumin a as 47 p er Cen t mightp ossibly be of use as a refractory , and a small sp ecimen from thelo cality was sen t to Dr. Mellor, o f Stoke - o n - Tren t

,by Mr . W .

Douglas , o f Kilwin n in g . A test made ' on this samp le gave the unexp ectedly high refractory quality of over Seger con e 35 (17700About the same time the late Dr . C. T . Clough was wo rkin g on

beds o f similar age and . character n ear Kilmarn o ck . He had

specimen s‘

collected,and bore the exp en se o f a series o f tests by

Dr . Mellor . The results,however

,showed that the samp les taken

were n ot n earlv so refractory as the material from Saltcoats .

1 40 Rep or ts (it Pr oceedi n gs— Ecl -in burgh Ge o log ica l Soc iety .

The clay occurs at the top Of ithe Millsto n e Grit Series,which in

North Ayrshire co n sists main ly o f a suite o f basic lava - flows,with

o ccasion al in terbedded fireclays, or of gan ister—like san dston es .

The lava series varies from 5 to 70 fathoms in thickn ess, an d usuallyrests o n an o ther fireclay , the Monkcastle Clay , ” which is n o t

bauxitic .

The upp er .members“

o f the lava series are o ften much decomp o sed,

and o ften pass“

almo st insen sibly upward either “in to beds o f po oriron ston e or o f bauxitic clay .

The clay varies in co lour from almo st white,through shades o f

grey , pin k, y ellow, o r brown,to j et black in hardn ess from that

Of a compact limeston e to a faky blaes ; and in texture from a

compact, practically n on - porous rock, with a . co n cho idal fracture ,to an almo st n ormal high—grade fireCIay ; but as y et it has n everbeen met with in an ythin g approachin g to a p lastic con ditio n .

In some cases it is seen to he a distin ct and separate dep osit ,'

but

in o thers it app ears to represen t a metasomatic rep lacemen t o f a

pre ex istin g rock . Man y o f the detrital samp les Show .a beautifuldevelopmen t o f o o litic structure, whi ch In “the main app ears to bedue to the ro llin g abo ut o f small fragmen ts (sometimes even o f

broken o o lites) o n the bo ttom of a Shallow p o o l o f water, which wascapable o f dep ositin g alumi n ous material . In a few cases a somewhat Similar structure has been develop ed by co n cretionary actio n .

The alumin a con ten t varies from26 p er cen t_

to 52 p er cen t ; an din varieties co n taini n g mo re than“

39 p er cen t (i . e . the amoun t o fA1

20 3 in kao lin ) , practically all the silica is in the combin ed stateas that material . The min eralogical n ature o f an y excess alumin awhich mi ght be presen t has n o t as y et been determin ed .

In man y ways the bauxitic clay 18 similar to bauxite, but di ffersfrom i t in that the alumin a is main ly In a combin ed form an d n o t

free . - There can be little doubt, however, that the two materialshave similar o rigin s, an d it appears likely that the clo se o f the Millston e Grit p eriod 1n North Ayrshire to ok p lace un der damp trop icalco n ditio n s

,with the result that the lan d surface of the lava flows

was subj ected to a p eculiar typ e o f decomp o sition kn own as

baux itization or lateritization ,which in this case seems to have

been accompan ied by reducin g con dition s, brought about by the

decay of large quan tities o f vegetable matter, producin g such gasesas carbon dioxide an d marsh gas, an d thus causi n g the Iron in themin erals presen t - in the basalts to be reduced to a so luble ferrouscondition ,

an d thus removable by p erco latin g waters . The alumin aalso seems to have gon e in to so lution ,

an d from the absen ce Of an }Tfo rm of free Silica in the dep o sit it app ears p o ssible that the twowere combin ed, formin g a so luble hydrous silicate o f alumin a,

which was capable of dep o sitin g kao lin an d free alumin a .

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142 Corr esp o n den ce—

“

L . F. Sp a th.

Such characters as size,

- Sp ecific gravity, chemical stability , and

so lubility all in fluen ce tran sp ortation an d subsequen t preservatio no f the min eral grain s which go to fo rm sedimen ts . The man n er o f

disin tegration o f the paren t rock is o f imp ortan ce in determin in gthe in itial size o f grain s derived from it . The agen t of tran sp o rt,whether win d or water

,takes charge Of the lo ose grain s, an d sorts

o r mixes, preserves o r destroys, accordin g to its particular attributeso f Sp eed, temp erature, an d comp osition . So lution after dep ositionmay so on er o r later remove the far - travelled remn an t . These an do ther prin cip les were passed in review . Fin ally ,

a most in terestin gdiscovery was an n oun ced . All the way from Sutherlan dshire an dthe Orkn ey Isles, in the n orth, to Yorkshire, in the south , san dston es an d grits, ran gin g in age from Pre - Cambrian to Triassic, areapt to y ield deep purp le - co loured zircon in beautifully roun dedgrain s ; an d this zircon has almo st certain ly been derived fromsome area ly in g outside o f Britain .

CORRESPONDENCE.

THE AMMONITE SIPHUNCLE .

SIR,

—In his in terestin g pap er on the Ammon ite Siphun clein last mon th ’s GEOLOGICAL MAGAZINE Dr . A . E . Trueman rej ectsmy suggestion (adap ted after Pictet

,etc . ) that a (n ot the ) fun ction

o f the siphun cl e in Nauti lus was to afford a mean s o f attachmen to f the an imal to its shell . I would gladly welcome a theory thatexp lain s all the facts (which my suggestion do es n o t do ) , but,

'

umfortun ately ,

Dr . Trueman do es n ot o ffer a better exp lan atio n . Heco n siders as mo re reason able , however, the op in io n o f Drs . Fco rdan d Wo odward

,who had suggested that the siphun cle was Of

more imp ortan ce in the y oun g , p erhap s then servin g for attachmen t I Thus

,it may be attachmen t after all

, an d the obj ection sthat I would adduce again st my own exp lan ation ,

Dr . Trueman do esn o t men tion

,n amely , (1 ) that histo logically the siphun cle o fNauti lus

is n o t a ligamen t , an d (2) that the con cen tric muscle - lin es indicatea gradual Shiftin g o f the shell—muscles durin g growth , con curren tlywith the secretio n o f gas . But

,while p erfectly willin g to admit

that in some primitive Nautilo ids an d also in the y oun g o f

Ammon o idea (which then had simp le sep ta) the eviden ce of attachmen t is, p erhap s, stro n ger, I do n o t thin k that we are justifiedin assumin g , as Dr . Wo odward did,

that the fun ction o f the siphun cleis p erformed,

in the adult Nauti lus,by the shell - muscles, as though

these structures were n o t presen t in the youn g . Nor is therean y eviden ce that the siphun cle is of less fun ction al imp ortan cein the recen t Nauti lus than in a homoeomorphous Silurian Shell ,o r again in a Cretaceous Ammon ite than in a Devon ian Gon iatite .My con ten tion was that durin g a fo rward move of the shell

muscles (the p eculiarly pitted app earan ce of the scars in some

Cor r esp on den ce— L . F. Sp ath. 1 43

fossil forms suggests a more secure attachmen t than in the livingNauti lus) some addition al mean s o f attachmen t was useful , an d thatthis was supp lied by (but n o t the o n ly fun ctio n of) the p en etratin gfibres o f the fo lded margin in Ammo n o ids an d the siphun cle in Nauti

lus . Sin ce the an imals with severed siphun cle men tion ed ' by Willeywere attached to their body - chambers by mean s o f the Shell - muscles(Willey p erformed the op eration at the base o f the body - chamber,behin d the an nulus) there was, of course , n o dan ger o f the an imalsfallin g away from the shells . Trun cation of the sep tate portion isn ot un common in fossil forms

,an d in some Discoceras (probably

on adap tation to a purely crawlin g mode of life) all the cameraewere cast Off an d the shell of the adult (an d n o t till then p ropagatin g )an imal con sistin g o f the body - chamber on ly . This merely provesthat there was n o further fo rmation o f sep ta,

an d the Shell - muscl esbecame p erman en tly attached to the shell - wall an d held the an imalfast, but it is n ot eviden ce again st my view .

On the o ther han d, it could be argued that owin g to its con

striction at the septal n ecks, the siphun cle o f even a trun catedProtobactrites or o f an Amphmeop sis (with on ly a few camerae)mi ght have been sufficien t for the purp o se of attachmen t . On ly hereit must be admitted that if this n o tchin g of the siphun cular tubeis lo okedupon as a stren gthen in g feature fo r such attachin g purp o ses,then a simi lar fun ction must also be assumed for Ammon o idea . In

some large section s before me (Parkin son ia dorseten sis , Phyllocerasheterop hyllum

I

) this con striction at the sep tal n eck 1s mo re apparen tthan In the (dried) Shells o f the recen t Nauti lus . On the o ther han d ,

inflation of the en do siphotube (between successive en do sipho

sheaths) and o f the e cto siphun cle (between the sep ta) is foun d inman y fossil Nauti li (I am n ot referrin g to the actin iform siphun cularstructures), and the sep aration o f these fromthe camerae by eitherthick min eral dep osits or by con tinuous sep tal n ecks do es n o t

favour an assump tion o f gas- secretion by the vascular siphun cle .

My op in ion certain ly was n o t based on the in terestin g , if un

scien tific, accoun t quo ted -by E . A . Smith A referen ce to thiswas g iven merely to show how the shell muscles in the livin gNauti lus became detached But the o rigin o f the siphun clecon striction o f the viscera, an d the vari ous structures i n themultitudin ous developmen ts o f the o rder Nautilo idea

,especially

the mo re primitive forms (Pi loceras and the Pro tero fo rms o f theCameroceras—Vagin oceras series) seemed to me most in structive ,as also the tran sition s from the endosiphun cular structures to thelater ectosiphun cle o f e .g . Baltoceras, which gen us Hyatt placed as .

the first o f his family Ortho ceratidae . I co llected a number o f veryin terestin g Lower Ordovician Cephalop oda in Newfoun dland some

seven y ears ago ,but their descrip tion is delay ed because it en tails

a revisi on of the classification of the who le order Nautilo idea . I mayalso men tion that the blackn ess of the outer coat o f the siphun clein P iloceras (the sp ecimen s are preserved In a do lomite

,exactly like

1 44 Co rr esp on den ce— S. S . Buckman ,

the Durn ess faun a) and the dark outer lay er o f the siphuncle incertain forms o f Vagin oceras suggested a differen t chemical composition but I could n ot get a mo lybdate precip itate . Myobservatio n s did n o t supp o rt an y of the previous exp lan atio n so f the fun ction o f the siphun cle, in cludin g those given by sué h

careful observers as Professor Blake an d Dr . Willey ,though there

was n o n eed to go in to them all again .

I may also men tio n that I would co n sider the typ ically regularsep'tatio n of Cephalop oda as a who le - and formation of chambersfilledwi th gas (as co n trasted with the tabulation ,

etc .,in o ther tabular

o rgan isms) to be mo re or less imp o ssible without the p o steriorlyattached siphun cle also that there may be a con n exion betweenthe attachmen t (in Ammon o idea) to the in flated begin n in g o f thesiphun cle o r caecum (itself attached by on e o r more ban ds

,the so

called prosipho n ) an d the progressio n o f the e nd of the pro to con ch(in phy logen y ) from asellate an d latisellate to an gustisellate , as

Opp osed to the reverse tenden cy o f the fo llowin g suture - lines todeepen the extern al lobe . But these suggestion s will be difficulto f demon stration .

In con clusio n ,I hope that SIn ce several siphun cular structures ,

n o tably Grandjean’

s membran e still remain un explain ed,

Dr . Trueman will con tin ue his in vestigation s in to the Ammon itesiphun cle . L. F . SP

'

ATH .

[This letter was received just to o late for in sertion in the Februaryn umber— ED . GEOLOGICAL MAGAZINE ]

THE GENOTYPE OF SPIRIFER.

SIR,— By some regrettable mischan ce certain errors o f referen ce

o ccur- in my commun ication to your Magazin e , January ,

1920,

pp : 18—20 . The fo llowin g co rrectio n s are required

p . 19 , lin e 5 from bo ttom,for MIC. ii

,pl . cclxiii read MC .

iii,pl . cclxvp . 20 , lin e 5 from top ,

fo r M.C. ii, p l . cxxv read MC . ii ,pl . cclxvp 20, lin e 8 from top ,

for M. .C ii read MC . iii_p . 20, lin e 12 from top ,

for read 41,42

I may also take the opportun ity to p o in t out that Sowerby ’

s

plate o f Sp irifer stI

7iatus i s n umbered In M.C. iii,

170 , whereasit ‘

is in tended for 270 The text says Sp irifer striatus,

Tab . cclxxi whereas it should be cclxx His index co rrectsthese errors .

I desire to than k my vigilan t friend Mr. Tutcher for n o tin g mylapses .

S. S. BUCKMAN .

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ASSISTED BY

PROF . J . W . GREGORY . D . sc F R . S . SIR JETHRO J . H . TEALL . S'

c .D'

F .R .S .

F . H . HATCH, PH .D ., PROF .

'

W . W . WATT S Sc D F .R . S .

PROF . J . E . MARR . SC .D F .R . S . HENRY WOODS , M .A F .R . S .

DR . A . SM ITH VVOODWARD . F .R . S .

APRIL, 19 20 .

CONTENTS

EDITORIAL NOTES

ORIGINAL ARTICLES .

The Pre - Glacial Val leys o f Arran

an d Sn owdon . By J. W .

GREGORY , F .R . S . (With 8

Text- figure s . )The Lim it between the Silurian

an d Devon ian Systems . By L

Carbon ife rous Fo ssils from Siam .

By F . R . COWPER REED . (WithPlate II . ) (Con cluded)

REVIEWS .

Blo ck Moun tain s in New Ze alan d . 1 78

Tin Ore s , 1 9 19 1 79

Marin e Borin g 1 80

Han dbo ok o f Min eralogy 1 81

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Phosphate s o f South Austral ia 1 81

Ge o logy o f Sin o ia , Rhode sia 1 83

Ore s Of Ton opah , Nevada 1 83

Sue ss as Palaeon to logist 184

Min e s of South Austra l ia 184Classification o fNephe l in e Rocks 1 85

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Ap p ly to JOHN WARREN, He lmin gham House ,LOWESTOFT .

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1 46 Edi tor ia l Notes .

IN the list o f those recommended by the Coun cil for election to

the Royal Society'

we are glad to se e the n ame of Dr . RobertBro om, of Griquatown , South Africa . The importan ce of

Dr . Bro om’

s work in an atomy an d zo o logy is gen erally recogn ized,bo th in its hearin gs o n the evo lution o f the higher vertebratesan d in its relatio n s to the study Of South African stratigraphy.

Dr . F , H. A . Marshall also ,though pre - emin en tly a physio logist

an d agriculturalist, has taken much in terest in the geo logical history .

of the vertebrates, _

an d in particular o f the domesticated an imals,o n which he has published some in terestin g details . But with theseexception s the list is, frankly ,

Very disapp o in ting . It do es n ot

con tain the n ame o f an y geo logist or of an y represen tative of theallied scie 'n ces Of min eralo gy -

an d geo graphy . This is very dis

couragin g to the workers in all these bran ches, n ow so numerous,an d i f thi s p o licy con tinues a deadlo ck will so on be reached, so thatman y emin en t geo lo gists, min eralogists, an d geographers who havereached the meridian of life will se e their chan ces of election .

indefin itely p ostp on ed, while for the youn ger gen eration the outlo okis unpromisin g .

VERY difleren t is the comp lexion of the similar list issued by theROyal So ciety of Edin burgh . This in cludes the n ames of n o lessthan four geo lo gists, n amely Mr . E . M. An derson , Mr . E . B . Bailey ,

Mr . R . G. Carruthers , al l members of the Geo logical Survey of

Great Britain ,an d Mr . W. R . Smellie , geo lo gist on the stafl

'

o f the

An glo - Persian Oil Compan y . Some of these gen tlemen are valuedcon tributors to our pages, an d we are glad to avail ourselves o f this .

opportun ity'

to ackn owledge with gratitude the support an d

en couragemen t that we have received from Scottish geo logists,an d esp ecial ly fromMr . Bailey , durin g the recen t crisis in the affairs:Of the Magazin e .

a

CAPTAIN W. B . R . KING,

M.A . , o f Jesus Co llege,Cambridge , formerly of H.M. Geo logical Survey ,

an d n ow Assistan tto the Wo odwardian Professor

,has been elected to a Fellowship :

at Jesus Co llege . We have already had o ccasio n to refer more than .

once to the brillian t work carried out by Cap tain Kin g as geo logist .on the Western Fron t , an d we con gratulate him heartily o n this:further distin ction added by his co llege to his well - deserved hon ours .

>l<

THE Geo logical So ciety of Lon do n an d the Min eralogical Societyhave set up a jo in t committee of twelve p etro logists to co n siderwhether an y stan dardization o f British p etrographic n omen clatureis p ossible and desirable, an d if so ,

to make recommen dation s withthat e nd in View The fo llowin g six members were n omin atedby the Geo logical So ciety Dr . J . S. Flett

,Mr . A . Harker

, Sir J . J .

Harris Teall,Dr . H. H. Thomas

, Mr . G. W. Tyrrell, an d Professor'

Edi tor ia l Notes . 1 4 7

W. W. Watts . The n omin ation s o f the Min eralogical Society are

as fo llows : Dr . J . W. Evan s, Dr . F . H. Hatch , Dr . A . Ho lmes,

Dr . G. T . Prior, Mr . R . H. Bastall , Mr . W; Campbell Smith . It isn o t y et kn own whethe r all the above n omin ees are willin g to serveo n the Committee . The first meetin g o f the Committee was heldat p m . o n March 16 , when a prelimin ary discussion to ok placeand certain reso lutio n s were drawn up for co n sideration at the n extmeetin g .

etc

WEhave been privileged;to se e a copy of a very in terestin gReporto f a Commission appo in ted to examin e the con ditio n o f the iro n an d

steel works in Lorrain e,in the o ccup ied areas of German y , in

Belgium,an d in Fran ce . A lthough the Rep ort is in the main con

cern ed with techn ica l en gin eerin g details of - the practice in thegreat iron and steel works o f these areas, n evertheless there are tobe foun d here an d there items o f in formation of g eo logical in terest,chiefly referrin g to the iron - ores of Lorrain e -

an d the coal o f theSaarBasin . It is obvious that the terms o f the Peace Treaty musthave an en ormous effect on the future of the iron an d steel in dustrieso f bo th Fran ce an d German y . Before theWar the iron - ore resourcesof Fran ce

,

an d German y were estimated at ton s an d

to n s, or approximately equal . The relative p o sition s

at presen t are about ton s an d ton srespectively . Thus Fran ce has '

n ow more than four times as muchiron~ore as German y ,

an d it is exp ected that in the n ear futureher an nual production will rise to ton s

,or double what it

was before the War and n early three times as much as the Britishoutput . But at p resen t the developmen t o f the in dustry is held upby the impossibility o f obtain in g from German y the regular supplyo fWestphalian co al stipulated for in the Treaty . Saar coal alon e isn ot satisfactory for blast - furn ace coke , an d requires an admixtureof at least 25 p er cen t of Westphalian or British cokin g coal . TheFren ch ironmasters desire to establish a reciprocal trade with thiscoun try ,

exchan gi n g Lorrain e basic pig - iron for British coke, butthe tran sp ort difficulty stands in the way . This may perhap seven tually be met by a system of can als . The scheme mo stfavoured is that kn own as the Can alizatio n of the Mo selle from

Thion ville to Coblen tz,with free n avigation o f the Rhin e to

Ro tterdam, o r

'

oan al from the Rhin e to An twerp . An altern ativep lan is for a canal from Dun kirk to the Briey ironfie ld . It iscon sidered that this scheme would cause in conven ien ce in cuttin gthrough the thickly p opulated in dustrial districts of NorthernFran ce

,an d the co st would be en ormous .

ORIGINAL ARTICLES.

The'

Pre - Glacial Valle y s o f Arran an d Sn owdo n .

l

By J . W. GREGORY, Un iversity , Glasgow .

CONTENTS .

The Val ley Sy stem o f North Arran .

Evo lution o f the Existin g Top ography .

Te cton ic Clefts an d Shatte r - be lts .

Amoun t of Glacial Excavation in the Val ley s .

Garbh Allt an d the Glacial Deep en in g Of Glen Ro sa.

Arran comp ared with the Main lan d of Sco tlan d an d Sn owdon .

INTRODUCTION .

HE history of the British Isles in the Pliocen e has an importan tbearin g on their glacial geo logy an d on the origin o f their existin g

geographical features . Phy siographic eviden ce in dicates that theLower Pliocen e was in Britain an ep o ch of depression ,

durin gwhichthe sea covered parts of South - Eastern En glan d,whereas the Middleand Upp er Plio cen e were marked by an up lift which excluded thesea from th e British Isles

,except in East An glia an d Western

Cornwall . It is gen erally agreed that this up lift raised the lowly in g plaIn s that had been formed durin g the Lower Plio cen e in top lateaus from 500 to feet above sea - level . The up lift lastedthrough a lon g period Of time an d such a slowly risin g lan d wouldn aturally be greatly denuded by rivers . Plateaus an d platformsdue to the Plio cen e up lift have been described by Dr . Mort forArran and by Professor W. M. Davis for Sn owdon ; y et in theirdiscussio n o f the presen t top ography o f those districts they attributea very slight influen ce to stream ero sion durin g the lon g pre - Glacialelevation .

The Island Of Arran , amon gst its man y o ther attraction s, oflers

much clear eviden ce o n the history o f this p lateau and'

its bearin go n the problem whether the Sco ttish valleys were made o r merelymoulded by glacial action . Dr.

”

Mort has recen tly so attractivelyrestated the case for the glacial origin o f these valleys, that it maybe advisable to -

summarize the eviden ce in favour of pre- Glacial

rivers havin g been the mo re importan t agen t in their formatio n .

Though Dr . Mort’s memo ir appears to attribute to ice to o large ashare in the formation o f the Arran valleys, it in cludes several such

1 Sin ce this pap erwaswritten , shortly after a revisit to Sn owdon in Sep tember,19 15 , the Plio cen e p lateau of Carn arvon has be e n de scribed by Mr Dewey ,

who demon strate s the p re- Glacial age o f the Sn owdon val ley s On the

Origin o f some Lan d - forms in Caernarvon shire , North Wale s”

GEOL . MAG . ,

19 18 , p p . 145—57, PI. VII. The publication of the p re sen t p ap er has be en

d e lay ed by p re- o ccup ation with o ther matters an d two y ears” abse n ce abroad

it is Issued as orig in ally written e xcep t for a few ve rbal chan ge s. I am gre atlyin debted to Dr. A . Scott, who durin g my absen ce kin dly re - drew the section s

for p re ss.

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1 50 Professor J . W. Greg ory

‘

feet . 1 The date an d mode Of formation o f that p lain are un certainbut it was probably out when the coun try was lower than at presen t ,and that p lain may have been n early at sea- level .The hi story o f the existin g valleys begin s with the elevation o f

this p lain in to a plateau . Durin g the up lift radial streams musthave flowed from the gran ite highlands . There are in North Arranabout twen ty - two radial streams in addition to the lower ends Of

the maj or valleys . These radial streams trend as fo llowsN.E . Two streams of North Glen San n ox .

E .N.E. Glen Sann o x .

E. Four streams n ear Corrie , of which the lon ge st is the White Water Glen .

S E. Merklan d Burn an d‘

Cn ocan Burn from Goatfe ll .

S . The e astern Garbh Al lt, from Ben Tarsui n n .

S.S.W. The we stern Garbh Allt from Bein n Nuis ; an d Auchen car Burn

from S .S.W. of Be in n Tarsui n n .

S.W.

'

Glen Scaftigi l l .

W. Eight burn s, o f which the lon gest is the Allt G obhlach.

N.W. Abhain n Beag .

These radial streams are all o f secondary imp ortan ce . Themaj o r valleys, in which groun d less than feet in height reachesthe cen tre Of the gran ite moun tain s

,run n orth and south . The

gran ite dome is, in fact, dissected by three main valleys which cutacross it n orth an d south . The lon gest and mo st co n sp icuous o f

these valleys is that .

_o f Glen Io rsa and Glen Easan Biorach it cuts

acro ss the middle o f the gran ite mass . Further east is the valleyo f Glen Rosa,

which is co n tin ued n orthward by Glen San n ox thisj o in t valley run s n o rth an d south fo r mo st o f its len gth , but bo thits lower en ds bend eastward to the sea . The third n orth and southvalley ,

that o f Glen Cataco l an d Glen Scaftigill , is on the westernside o f the islan d its lower en d ben ds westward to the sea,

whichthe Scaftigill Burn reaches through the Io rsa Water . Each of thesethree valleys in cludes a large tract of ground below the level o f

feet . On the flo or o f Glen Iorsa a ban d o f alluvium, most o fwhich is below the level o f 250 feet, o ccurs in the very cen treOfNorth Arran ; even the upp ermo st part of this alluvium IS below350 feet . Most Of the flo ors o f Glen Ro sa and Glen San n ox are

less than 500 feet above the sea .

In addition '

to the three n o rth an d south valleys there is an o thermaj or valley in North Arran . It con sists of Glen Chalmadale and

North Glen San n ox ; it crosses the islan d from Lo ch Ran za eastsouth eastward to San n o x Bay an d separates the p lateau o f CreagChlass Laggan (1 ,453 feet) from the rest o f the highlan ds .

The valley system o f North Arran may therefo re be classified as

fo llows :A . Min or Vall ey s.

I. Radial val ley s from the gran ite hil ls.

B. Maj or Valley s .

II . The thre e n orth to south val ley s acro ss the gran ite hil ls.

1‘ This fe ature was recogn ized an d illustrated by Sir A . C. Ramsay (1841 ,s ect. i , Opp osite p :

The Pr e - Glaci a l Va l ley s of Arran an d Sn owdon . 1 51

III . The n orth - we st to south - e ast. val ley acro ss the n orth - east o f the

i slan d betwe en Lo ch Ran za an d San n o x Bay ._

IV. The valley which crosse s from Brodick over a divide at 768 fe et

an d sep arate s the moun tain s Of No rthArran from the mo orlan ds that formmo st Of the southern p art of the islan d.

2 . EVOLUTION OF THE EXISTING TOPOGRAPHY .

The most Strikin g feature o f the maj or’

valleys o f North Arranis their in depen den ce alike o f themain slop es and geo logical structure .’The maj or valleys are n ot radial from the moun tain s an d they are

in dep endent of the geo logical structure . Thus the three n orth an ds outh valleys cut right acro ss the gran ite mass, and though theirlower

'

ends bend seaward this chan ge o f course app ears in dependen to f the structure o f the schisto se an d sedimen tary girdle . lHowever greatly the vall eys may have been en larged by denuda

tion,their plan was determin ed by some influen ce which affected

the area as a who le an d was indep enden t of its structure .In o rder to determi n e the o rigin of these valleys and the exten t

to whi ch they are due to glacial ero sion it is n ecessary to determin ethe gen eral topography o f the coun try at the begin n in g Of its glaciation . That topography was the result Of the geographical evo lutionOf the island after the ign eous activity o f the middle Kain o zo ic .

The n ext pro cess was the plan in g o f Arran to a gen tly un dulatin gtableland, o f which the surface in the Goatfell Moun tain s was,perhap s, feet above sea- level . The lan d exten ded further on

all sides,an d the Slopes were lo n ger and gen tler than they are n ow .

Durin g this stage Arran was part of the main land and,as Dr . Mort

suggests, the Chalmadale —North San n ox valley was probablyin itiated then by rivers that flowed south - eastward across NorthEastern Arran . The coun try was again uplifted,

and Arran was

iso lated by tecton ic valleys to east an d west, and a series o f n orthan d south clefts parallel to these valleys cut acro ss the gran itemass o f

'

North Arran . The clefts were subsequen tly en larged bydenudation in to the three maj or n orth and south valleys o f theisland .

After the seco nd up lift the land must have remain ed station aryfor a sufficien t p eriod, for the fo rmation o f a low p lain , which wasraised by a third movemen t in to the thousan d—fo o t platform(Fig . This uplift doubtless reop en ed the n orth an d south clefts ,

1 Amon g the valuable con tribution s in Dr. Mo rt’

s p ap er is his re j ection of

the Vi ew that the differe n ce in form betwe en the cen tral an d we stern m oun tain s

was due to the te xture Of the grani te . His obj ection s to that e xp lan ations e em con vi n cin g . The we ste rn hills were comp lete ly overridden by ice , o f

whi ch the l ower p art woul d have be en charged with ro ck de bris from the

smo oth ce n tral p eaks an d would have worn down the we stern summits in toroun ded ridge s . The l ower p art of the sn ow - cap over Cir Mhor an d Goatfe ll

may have be en con verted to ice but after the ice -had removed the lo o se

material it would have con sisted of cle an ice an d have had but little abrasive

p ower. By the time it had reached the we stern hill s the l ower lay ers werep robably charged with ro ck fragmen ts an d were thus a more e ffe ctive file .

1 52 Pr ofessor J . W. Gr egory;

and they were en larged by denudation un til their flo ors were butlittle above sea - level . Durin g these movemen ts the climate wasbecomin g co lder, as is shown by the disapp earan ce from the Britishseas of tho se Lower Plio cen e mo llusca that are characteristic o f

warmer condition s . Frost action must have attacked the higherp eaks an d esp ecially the slop es facin g n orth and east ; an d thecon tinual freezin g an d thawin g of water in the j o in ts of the gran iteled to the fo rmation o f corries alon g the margin s of the sn ow - fie lds .

Dr . Mort’s memo ir o n Arran gives the first adequate descrip tio n of

its thousan d fo o t p latform,which is also well develop ed in Ayrshire .

Dr . Mort has advan ced good reason s for the op i n i on that it waspro bably due In Arran to marin e denudation .

1 If so ,this p latfo rm

i s eviden ce o f an up lift of at least feet , and that it was severalhundred feet greater than that amoun t is shown ,

as Dr . Mort remarks,by the buried valleys in South—Western Sco tlan d . If this platformbe a p lain o f marin e denudation the uplift in Arran was n ot un iform .

The p latform varies in height from 800 to feet aroun d theGo atfell Moun tain s, an d to the n orth - west of Brodick . It is from700 to feet beside the western coast from lower Glen Iorsan orthwards to n ear Pirnmill from 750 to feet n orth of NorthGlen San n o x from 500 to 750 feet in the south - western part of theisland, between Blackwaterfo o t and Glen Scorrodale an d between500 or 600 feet and 900 feet in the south - eastern part o f the islan d .

That the up lift was differen tial agrees with the aspect Of the lan das seen from the steamer when approachin g Brodick, as the p latformslop es gen tly downward from the Goatfell Moun tain s bo th to

south and n orth . That the greatest up lift occurred n o rth Of Brodick '

was recogn ized by Sir Andrew Ramsay (1841 , section i , oppo sitep . who rep resen ted the island as part of a great an ticlin e withits axis en din g on the eastern coast at North San n ox .

The uplift o f the thousan d - foo t p latform was. un question ablypre

- Glacial,for deep valleys with glaciated flo ors, on which are well

p reserved mo rain es, had been cut through it to the level o f less than100 feet above the sea . The effects o f p ost - Glacial denudation on

the island have been comparatively trivial ;gorges, sometimes 30 feetdeep , have been cut by streams through easily denuded ro ck . Thep o st - Glacial p eriod has been very short compared to that o ccup iedby the formatio n Of the maj or valleys .

In Glacial times Arran was a lo cal glacial cen tre . Ice formedover the moun tain s o f North Arran an d flowed radially to the sea .

Dr . Mort quotes with approval Gun n ’

s remark that Arran had a

lo cal icecap which shed material all roun d (Gun n ,1903

,

1 Profe ssor Davis (1909 , p . 289 ) give s as a criterion for the di stin ction of

marin e from subae rial p lain s that i n se a cut p lain s the border o f the n u

reduced masse s should have be en a se a cl iff ;while In subaerial p lain s therewould p re sumably be a gradual tran sition from un reduced masses to the

reduced p lain”

As Dr. Mort p o in ts out, the abrup t e n din g of the p latform

again st the moun tain s favours the marin e origin o f this p lain .

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1 54. Professor J . W. Greg ory

pp . 132 From the high groun d o i the in terior,

says Dr. Mort,

glaciers diverged, which fin ally jo in ed the main streams,and

moved south down the. Firth (Mort, 19 14, p . The flow to

the n orth was blo cked by ice from the main land, an d the chiefdischarge was southward . AS gran ite erratics from Arran are

rarely foun d in Ayrshire its ice must have been deflected to thesouth immedi ately after leavin g the islan d by ice from the n orth .

If the Arran valleys had been formed by the radially flowin gice they should have been radial from the gran ite cen tre, and it hasbeen claimed that they run app roximately from the cen tre inradial fashi o n (Mo rt, 19 14, p . This is true o f the min or valleysbut the mo st con sp icuous feature in the arran gemen t o f the majorvalleys of Arran is that they are n ot radial .Dr . Mort remarks (op . cit .

,p . 71 ) that the Arran glen s presen t

features which can n o t be exp lain ed by n o rmal stream erosio n and

this V iew is certain ly co rrect as regards their plan ,which would

n ot have been adopted by streams flowin g from the gran ite dome o fNorthern Arran un less the denudation had been guided by preexistin g lines o f weakn ess . The Same obj ectio n ,

however, woul dapply to ice ero sion ; for, un less guided by pre - Glacial valleys, glaciale rosion should also have produced valleys radi al from the highground . The maj or valleys were probably determin ed by structurallin es o f weakn ess due

' to the up lift o f the area . Glen Rosa and upperGlen San n ox o ccur alon g a basaltic dyke, which is the lon gest dykein Arran . This dyke was forced in to a n orth and south rift formedbefore the end of the ign eous p eriod . The uplift which fo rmed thethousan d - fo ot platfo rm probably caused a series Of n o rth and _

southfractures whi ch did n ot

_ prodIIce man y faults, but rifts or ban dso f rup tured weaken ed rock (the shatter- belts o fMarr) . The streams

n aturally fo llowed these rifts and weak ban ds, an d thus the maj o rvalleys of North Arran were a series of three n o rth an d south valleysacross the gran ite blo ck . That these three valleys were tecto n ic ino rigin app ears to be further indicated by their agreemen t with thegen eral structural lin es o f the district . The gen eral course of theeastern an d western coasts has been determin ed by faults an d

fractures . Kilbren n an Soun d to the west and the main Firth o f

Clyde to the east are probably bo th sunken blo cks, which havebeen let down by n orth an d south trough faults an d the block ofNorth Arran was doubtless ren t by n orth an d south clefts formed bythe same series o f movemen ts .

3. TECTONIC CLEFTS AND SHATTERl BELTs .

The .valleys , however, are n ot faul t valleys , as n o recogn izabledisp lacemen t has taken p lace amon g them . They may be Simp leclefts formed by the gap in g of fractures in ro cks un dergo in g ten sio ndurin g up lift . The n ecessary formatio n o f such ten sio n clefts hasbeen rep eatedly asserted

,as e . g . by James Smith in 1862 (p .

by Ruskin (1856, vo l . iv, p . 229 , i_

. e . pt . V,ch . x v, p . and Bailey

The Pre - Glaci a l Va l ley s of A rran an d Sn owdon . 1 55

Willis (1893, pl . lxxv ) . Such ten sion clefts would be n arrow, but

would be en larged by the streams that would flow alon g them .

Broader valleys would be formed where ten sion is relieved bya mul tip le in stead o f by

-

a simp le fracture . This multiple fracturemight con sist o f parallel fractures co n n ected by cross. fractures , o rO f an astomosin g bran chin g fractures . Suchmultip le fractures wouldproduce a belt o f shattered ro ck and thus form o n e variety Of theshatter- belts of Professo r Marr . His defin ition (1906, p . 77 ; re

:afli rmed 19 16, p . 71 ) attributed shatter- belts to o scillatory faults,which cause n o fin al disp lacemen t as the ro cks on bo th sides are

r estored to their origin al position s by the backward an d forwardm ovemen t . He describes these belts as man y yards in width an d

as composed of ro ck broken in to a rubbly mass o f an gular frag“men ts o f vary in g size in a matrix of fin er crushed material Suchbelts Of shattered material may also be formed by ban ds of ro ckbein g torn to pieces by ten sion cracks ; an d some shatter- belts o f theLake District would appear to be more easily explain ed as multiplean astomosin g ten sion clefts than as faults and the broader valley so f Arran and the maj or valleys of the rectilin ear system around

Sn owdon may o ccur alon g shatter- belts due to ten sion durin g thePliocen e up lift . Shatter - belts probably o ften o ccur where they can n o tbe seen

,for they woul d be seldom exp osed on the flo ors o f the valleys ,

and quickly obscured o n the sides an d in the absen ce Of clear ex fp osures, shatter - belts formed as crush breccias are in distin guishablefrom those due to multip le ten sion fractures . The term shatter - beltmay be conven ien tly used for bo th kin ds .

4 . AMOUNT OFGLACIAL EXCAVATION IN THE VALLEYS .

With the in creasin g severity o f the climate the coun try was

o ccup ied by glaciers, and they found an immature topography o n

which even limi ted glacial erosion would have produced con sp icuousresul ts . The ice flowin g down the valleys must have pressed again stthe spurs

,cut them back, and thus rendered the n orth and south

valleys trough - shap ed . There seems n o’

convin cin g eviden ce thatthe ice materially deepen ed the valleys . Some of the alluvial plain smay cover bur ied chan n els formed at the same time

'

as‘ tho se on the

main lan d ; but n on e o f the freshwater lo chs o f Arran have flo orslower than sea - level . N0 kn own Arran valley has been excavatedbelow the base - level Of the pre—Glacial rivers . Accordin gly there isn o n eed to assume the glacial deep en in g o f the valleys .

The amoun t o f hard ro ck removed by ice in widen in g the valleyswas n ot n ecessarily con siderable . Tha ice doubtless wo re away thespurs, some o f which are n ow represen ted o n ly by blun t gables o n

the hill - sides,Sli Ch as Torr Breac at the ben d o f Glen Ro sa . The

smooth Spurless slop es at first give the impression of exten sive icee ro sion . But if

,as seems most probable , the three n orth an d south

valleys were formed alon g ten sion clefts made by the up lift, theiro rigin al course would have been straight and the spurs on their

1 56 Pr ofessor J . W. Gr egory

sides would have “been short an d blun t . Their pre - Glacial walls.p robab ly sto od quite clo se t0 '

.the existin g walls . On e of the bestkn own ice - worn slop es in Arran is the southern face o f Creag Ro sa .

But a sectio n acro ss this, slop e based -

o n the Ordn an ce map s (Fig .

even with the vertical scale magn ified twice , do es n ot give theimpression o f an y great overde ep en in g . If the flo or o f the valleyhad been at its presen t dep th in pre—Glacial times, the dotted lin e onthe figure would indicate the approximate p osition of the preGlacial slop e, The greatest thickn ess of ro ck removed by the icewould o n ly have been about 100 feet

,and this lay er would have been

weaken ed by pre- Glacial disin tegratio n . The thickn ess o f hard

fresh ro ck removed would have been in sign ifican t .5 . GARBH ALLT AND THE GLACIAL DEEPENING or GLEN ROSA .

Dr . Mort,however

,ho lds that GlenRo sa was glacially deep en ed

to the exten t o f between 500 an d 800 feet, a co n clusio n based main lyo n the han gin g valley

'

of Garbh Allt . This stream rises on

'thesouth—eastern slop es o f Bein n Tarsuin n ,

an dl

at first fl ows south .

south - east'

p aralle l to Glen Ro sa ; at 800 feet it bends sudden lyeastward

,an d is j o in ed by a tributary from the west it fo llows the

directio n o f this stream an d discharges to the east - n orth - east bya series o f cascades to Glen Ro sa . It comes from a han gin g valleywhich ends 500 feet above its con fluen ce with the Ro sa Water ;an d Dr . Mort ho lds that the differen ce in leve l

_

betwe en the han gin gvalley an d the Rosa Water is due to glacial deep en in g -

of at least500 feet an d p erhap s o f 800 feet .The limited corro sion by the lower GarbhAllt 1s capable of anotherexp lan ation . Dr . A . Sco tt suggested to me the po ssibility that theGarbh Allt was o rigin ally the head o f the Easbuig Burn (Bishop ’

s

Glen ) , a tributary o f the Machrie Water ; an d a visit to the lo calityshowed the high probability o f the suggestio n . Figs . 4 an d 5 showfive sectio n s acro ss the hills to the west o f Glen Rosa . Section 4A

cro sses the upp er part o f the Garbh Allt, which there flows througha valley clearly sep arated from the parallel valley o f Glen Rosa .

Section 43 cro sses the middle part o f the Garbh Allt where theeastern side of the valley 1s in con sp icuous . Section 40 1s alon g thelower course of the Garbh Allt below the right - an gled bend at

800 feet , the section is co n tinued westward alon g the tributarywhich con tin ues the “

course o f the cascades o f the Garbh Allt .

Section 5D is alon g the low flat rise which separates Garbh Allt fromGlen Easbuig to the south - west

,an d from the tributaries of Glen

Shurig to the south - east . Sectio n 5E cro sses Glen Easbuig fromn o rthjwest

'

to south - east at the same distan ce from D as that isfrom Section C and as C is from B . These section s show a co n tin uousvalley which was p robably the o rigin al course o f the Garbh Alltwhen

,in stead o f turn in g to the east at C,

it descen ded from feet "

in B,over the . depression at a little over feet in Section D to

'

Glen Easbui g . T he Garbh Allt has n ow been diverted eastward to :

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1 60 Pr ofessor J . W. Gr eg ory

valleys vary in d irection they do so at sharp an gles . Thus theNan t Gwyn an t run s n orth - eastward from Beddgelert to Pen ygwryd,where it ben ds east - n '

orth - eaSt to Capel Curig an d on the con tinuatio n o f its o rigin al direction o ccurs the valley o f Llyn Cawlyd . TheNan t Gwyn an t

—Llyn Cawlyd valley is approximately parallel tothe remarkably straight course of the 500 ft . con tour alon g then orth - western and western slop es of Sn owdon ia .

These rectilin ear valleys have cut across some o f the o lder valleys .

Thus the formation o f the Llyn Cwe lly n valley beheaded the Afo nDrws -

y- co ed (the upp er part of the Nan tlle valley ) an d cap tured

its o rigin al head streams in the Cwm -

y- Clogwyn ,

which,bo th from

direction and gradien t, app ears the n atural con tin uation o f theAfon Drws -

y- co ed .

The course of this n etwork of valleys is n ot what would bean ticipated if they had been excavated by me . If the valleys wereg lacial in origin they would have been exp ected to radiate fromSn owdon ,

whereas the moun tain is an oblon g blo ck en clo sed in a

rectilin ear moat . The blo ck would be almo st an exact oblo n g butfor the sharp ben d in the south western valley , which adds a

trian gular area to the southern corn er .

A secon d resemblan ce to Arran 1s that Snowdon , as was clearlyp o in ted out by Sir Andrew Ramsay (1881 , pp . 271 was n evercompletely overridden by extran eous i ce . It was a cen tre o f localglaciation ; an d as Ramsay remarked of its n orth - western glaciers(1881 , p . on escap in g from the high - boundin g - walls of theupp er parts o f their valleys , they partly spread out in the shap e o fbroad fan s o n the n orth - western slop es o f the min o r hills thatn ow overlo ok the Straights .

”

Accordin g to Ramsay , therefore ,the valleys were p re - Glacial . The question is merely how far theg laciers en larged and deep en ed these pre - existin g valleys . Theamoun t dep en ds up on the co n dition of Sn owdon ia at the begin ni n gof Glacial times an d

, like the moun tain s o f Arran , Sn owdon wassurrounded by a high p latform tren ched by pre - Glacial valleys .

Sn owdon ,at o n e part o f the Plio cen e, was apparen tly a moun tain

about feet high surroun ded by a low,widespread plain . The

district was raised by a Plio cen e up lift, and the plain formed thep latform that n ow surroun ds Sn owdon at the height o f fromto feet . This p latfo rm o ccupies mo st of the area between the

and ft . con tours o n the map (Fig . It is shown inRamsay

’

s section through Yr Aran (1881 , p . 158, fig . thep latform is at the level of from to feet to the n orthwest of Yr Aran ,

an d somewhat lower to the south - east o f it .The up lift of Sn owdon ia led to the erosion o f can y on s alon g the

flo o rs o f the o ld valleys, the width o f which indicates that they hadb een worn down to base- level and their walls cut backward before theGlacial p eriod . As the climate became mo re severe the gullies on theupp er sides o f these gorges were o ccup ied by sn ow, an d corries weree xcavated about them by the combin ed action o f frost an d streams .

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1 62 Professor J . W. Greg ory

When the glaciers flowed down the valleys they would have wornback the spurs, levelled the bars of ro ck o n the flo ors, an d thus thetrough shap e o f the can yon s, due o rigin ally to their formatio n alon grectilin ear fractures, was rendered more comp lete The amoun t o fso lid ro ck removed by the ice accordin g to this con cep tion of thehistory o f Sn owdon was very small in comparison with that invo lvedin the exp lan ation adop ted by Pro fessor Davis . In his well - kn ownpaper bo th in the text an d in an illumin atin g sketch (Davis,1909 ,p . 307) he represen ts Sn owdon at the begin n in g of the glaciationas a down - like up land;with gen tle slop es an d shallow valleys , clifli esscragless, an d without either corries or river go rges . In his pap er(1909 , p . 282) he describes pre - Glacial Snowdon as a

'

subdued

FIG . 7 — Section from Sn owdon to Myn ydd Mawr through Llyn Cwe l lyn .

The broke n l in e rep re sen ts the approximate surface at the beg in n in g ofGlacial time s , on the hypothe sis that the down - l ike re l ief has be e n de stroy edby g lacial ero sion . The areas in so l id black repre se n t the amoun t o f so l id

ro ck removed on the altern ative hyp o the sis that the val ley had be en

excavated to approximate ly its prese n t dep th by pre - Glacial streams .

moun tain form with dome - like cen tral summit, large rounded spurs,and smo o th waste covered slop es, and with mature valleys drain edby steady flowin g ”

streams He main tain ed (ibid . ,p . 281 ) that

Sn owdon was altered durin g the Glacial p eriod an d chiefly by glacialerosion from

‘

a large featured, round - shouldered, full bodiedmountain o f pre

-

glacial time “ in to the sharp featured, ho llowchested, n arrow spurred moun tain of to

Professor Davis accep ts the “ late Tertiary up lift of Sn owdonbut con siders that this would n ot have seriously chan ged its

top o graphy , as the on ly effect would have been the formation of a

fewmin or gorges (p . This conclusion is based on two argumen ts,first that Sn owdo n has n o large trun k rivers, an d the streams are n otsufficien tly differen t in vo lume to exp lain why some out their valleysdeep ly and o thers were left as han gin g valleys . These argumen tswould be con clusive if the valleys had been cut by n ormal con sequen t

The P o e - Glacia l Va l leys of A ’rr'

an an d Sn owdon . 1 63

streams flowin g down a un iform dome . But if the maj or valleysbe regarded as a reticular system formed alon g fractures whichgap ed open at the up lift of the coun try , they could have been madewithout trun k rivers ; and the dep ths of the main valleys as com

pared with some o f their tributaries i s .a n atural con sequen ce of themore rap id denudation alon g the tecton ic rup tures .

Pro fessor Davis supports his case by referen ce to the roundedmoun tain s, or

“ '

Mo e ls He ho lds (1909 , p . 293) that they weren o t overridden by n orthern ice or overwhelmed by the lo calice an d that their rounded forms have been retain ed from pre

Glacial times ; an d he therefore claims that the adjacen t valleyswere also rounded then . But if the Mo e ls on the n o rth west spursof Sn owdon have retain ed their pre G— lacial forms, they would tellagain st the view that the moun tain has been greatly altered byglacial erosion , sin ce some of them were in posi tion s especiallyexp osed to abrasion by the me from cen tral Sn owdon .

Summi tDurarddq

Ll a n.

FIG . 8 .- Hyp o thetical ske tch o f Sn owdo n from the n orth - we st at the en d o f

pre- Glacial time s , il lustratin g the val ley s formed in con sequen ce o f the

Pl iocen e up l ift.

As Sn owdon stan ds in a positio n which ren dered it subj ect toa heavy precip itatio n and is very varied in structure an d compo sition ,

it app ears improbable that it should have suffered“

so little from'

stream ero sion durin g the lon g Pliocen e uplift, as is admitted byProfessor Davis’ exp lan ation . Accordin g to his view, on thesection from Myn ydd Mawr across Llyn Cwe llyn to Sn owdon ,

thepre

—Glacial flo or o f the valley would have been at the presen t levelo f about feet Sn owdon and Myn ydd Mawr would have risenfrom the valley in gen tle mature slop es alon g the upper boundaryof the shaded area in Fig} 7 . The valley below the broken lin ewoul d have been excavated by glacial action .

Accordin g to the altern ative view the pre - Glacial surface wasalon g the . lower lin e ; the valley was a deep tren ch in theto ft . p latfo rm ; the bed o f the lake is 122 feet lower(Jehu, 1903, p . The greatest removal o f so lid ro ck by theice would have been alon g the edges of the Llyn Cwellyn Valley ,

and the amoun t removed would have been approximately that

1 64 L . Dudley Stamp— Limi t between

marked in so lid 'black . Accordin g to this in terpretation thetopography o f Sn owdon at the begin n in g o f the glaciation was

essen tially the same as it is n ow. Professor Davis’s sketch probablyshows the n atur e of the moun tain slop es in the early Plio cen e ; but atthe e nd o f that p eriod the in creased p ower given to the streams bythe up lift had en abled them to deep en their beds un til they flowedthrough steep - walled gorges . The asp ect of the moun tain if seenfrom the n orth - west would probably have been approximately as

represen ted in Fig . 8 . The.

earlier down—like relief had beenmo stly destroy ed ewin g to the excavation of the valleys of

Sn owdon ia,like tho se o f Arran

,by streams durin g the Middle and

Upp er Plio cen e up lift . 0

REFERENCES.

DAVIS (W. 1909 . Glacial_Ero sion in North Wales

Ge o l . Soc. , lxv , p p . 281—350 , p l . x iv.

GUNN 1903. In The Geo logy of North Arran

Surv. Scotlan d, She et 2 1 . p p . viii , 200.JEHII (J. 1903. A Bathymetrical an d Geol og ical Study o f the Lake so f Sn owdon ia an d Eastern Carn arvon shire Tran s. Roy . So c.

Edi n burgh, x 1, pp . 4 19—67, 8 p lates .

MARR (J . 1906. The In fluen ce of the Ge o l ogical Structure of En glishLake lan d up on its p re sen t Fe ature s Quart. Journ . Ge o l . Soc. ,

lxii ,p l xvi—cxxviii .19 16. The Geo logy of the Lake District. p p . xi i , 220, map .

MORT 19 14 . North Arran A Physiograp hic Study . 72 p p . , map .

RAMSAY (A . 1841 . The Geo logy of the Is lan d of Arran . p p . 78 . Glasgow.

1881 . The Geo logy of North Wa les . Mem. Ge ol . Surv: Great Britain ,

iii, 2n d ed. p p . x ii , 6 1 1 , 28 p late s .

RUSKIN 1856 . M odern Pa in ters, iv.

SMITH (JAMES) . 1862 . Newer P l iocen e Geo logy . p p . x i , 192, 4 p late s.

WILLIS (BAILEY ) . 1893. The Mechan ics of Appalachian StructureAnn ual Rep ort US . Ge o l . Surv. , p t. ii, p p . 2 1 1—82, p ls. xlvi—xcvi .

No te o n the De te rm in atio n o f the Lim it be twe e n the

Silurian an d Devo n ian Sy stem s.

By L . DUDLEY STAMP, M.Sc . F. .G.S

IN a recen tly published pap er on the Highest Silur ian Ro cks of

the Glun Forest District, Shrop shire the presen t writer gavean accoun t o f an area where the series o f passage - beds markin ga gradual tran sition from Silurian to Old Red San dston e con di tion s,is well seen . The succession there is practically iden tical with thatestablished by Miss Elles an d Miss Slater in the Ludlow District . 2FromNovember, 1918, to October, 19 19 , whilst en gaged in a studyo f Belgian Tertiary rocks, I have had an opp ortun ity of visitin gsome of themore imp ortan t section s o f the Gedin n ian in the Arden n esan d also of examin in g the palaeon to lo gical co llectio n s at Brussels,Lille, an d elsewhere . This work has thrown very con siderable

1 Quart . Journ . Ge o l . So c . , vo l . lxxi'v, 19 18, p . 221 , 19 19 .

2 Ibid -vo l . lxii , 1906, p . 195 .

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1 66 L. Dudley Stamp — Limi t between

of the Temeside shales of Shropshire . The discovery of marIn efo ssils in the latter has shown the fo lly o f iden tify in g this typ e oflitho logy exclusively with lacustrin e con dition s .

The Gedin n ian has a similar facies to the south Of Pep in ster.

(c) The Meuse Valley, south of Givet.Here some sp len did section s show the Poudin gue de Fepin— a

thick, though lo cal , con glomeratic base o f the Arkose de Haybesm

restin g o n the up turn ed an d eroded beds of the Cambrian . TheArkose is succeeded by the Schistes de Mondrepuits (which are n o t

here very fossiliferous) and then by the Upp er Gedin n ian .

(d) Mondrep uits and Macquen oise

Here o ccur the most fossiliferous exposures of the Lower Gedin n ian(Schistes de Mon drepuits) . The most abundan t fossil 1s Rhyn chon e llan ucula

,again the small form o f the top o f our Chon etes Beds . Other

characteristic fossils in clude Pterin cea retroflema ,Bellerophon tri lobatus,Sp irifer suleatus, and Orthis p erson ata (Zeiler) , the latter (wellkn own from the Coblen tzian ) indicatin g clearly the affin ities

“

Of the

faun a with the succeedin g Devon ian .

B . THE NORTH OF FRANCE (PAs - DE - CALAIS) .

Durin g the German occupation of Lille,Professor C. Barro is,

Dr . P . Pruvost,an d M. G. Dubo is emp loy ed the leisure o f“ their

forced confin emen t in the city in study in g a large series o f specimen so f Silurian an d Devon ian ro cks from shafts an d borin gs

“

round

Lievin ,Len s

,Bethun e, etc . A comp lete series o f tran sition ro cks

from the Silurian (Aymestry horizo n ) to the Devo n ian o ccurs in

this region ,thrust over the Pas - de - Calais COalfie ld . Results of very

great in terest an d importan ce have resulted from this study ,o f

which, apart from previous descrip tion s o f a smal l part of the

faun a, o n ly a sho rt resumé has y et been published .

2

I am deep ly in debted to Pro fessor Barro is an d Dr . Pruvost, who

have allowed me to examin e the specimen s at the Un iversity of

Lille .The success10 n established Is as fo llows

Thickn e ss in metre s .

Schiste s et gres rouge s et verts de

d' about 200

Ge In n l en sup eri eur Schiste s et gres roug es et ve rts de

Pe rn e s

Psammite s de Ll evin

Gedinmen mférieur Schistes de MericourtArkose de Bo is - Be rn ard

Grauwacke de Dro court

Gothlan dien superieur Calcaire d’An gre s

Calcaire de Lievin

1 Go sse le t, Barro is, Le I iche , Crép in ,De scrip tion de la Faun e siluro

d évon ien n e de Lievin Mem . So c . geo l . du Nord, vo l . vi (ii ) , 19 12 . Le richeMem . So c. geo l . du No rd ,

vo l . v,1906 .

2 GR des Sean ces de l’Acad . des Sci . (In st. de Fran ce ) , vo l . 167, 19 18, p . 705 .

Si lur i an an d Devon ian Sy stems .

The Calcaire. de Lievin has y ielded six species,with Bayia

n a'

vicula in great abun dan ce .The Calcaire d’

Angres is a blue limeston e , crin‘

o idal at the base ,with thirty - two species

,in cludin g Rhyn chon ella n ucula (large form

iden tical with the characteristic form foun d in our Rhyn chon e lla

Beds) , Acaste Down ingias, Calymen e Blumen bachii , an d“

Lep'

tcen a

rhomboidalis .

The Grauwacke de Dro court has y ielded sixty - three sp ecIes,

in cludin g Sp irifera e levata, Orthis lun ata,0 . can alieulata,

Homalon otus spp .,Pterin oea retroflexa ,

an d numerous Orthoceratids,in cludin g the n odules a Orthoceras so well seen in theRhynchon ella an d Chon etes Beds of Shropshire . 1The Arkose de Bo is - Bern ard is a local bed of coarse san dston e

at the base '

o f the Schistes de Mericourt .The Schistes aTen taculites de Mericourt y ield a very rich faun a o f

fifty- eight sp ecies, in cludin g Retzia Bouchardi , Ten taculite

'

s irregularis,Pterin cea retrofleaa,

_

an d o ther lamellibran chs, Gryp haeas spp . ,

abundan t Primitia Jon esi, Orthis p erson ata . There can be n o doubt

O f the iden tity Of this -bed with the Schistes de Mon drepuits .

The Psammites de Lievin have altern ating beds with PterasjoisGosseleti (Leriche) , Cyathasp is Barroisi (Leriche) , an d typ ical marin ebeds with Modio lop sis comp lan ata an d Orbiculoidea .

The Schistes et grés de Pern es and the Schistes et grés de Vimyare on ly separable by their faun as , the . former bein g characterizedby Pterasp is Crouchi i , Pt. rostrata, and Cephala sp is Lyelli ; thelatter by a rich an d en tirely differen t series of fish r emain s n o t

y et described .

C. SHROPsHIRE .

It is n ot n ecessary to repeat here the well - kn own establisheds equen ce in Shropshire .The beds

,which I have termed in the western area the

Platyschisrn a shales,represen t a deep er water facies of the lower

part o f the Down to n Castle Sandston e . The fossils men tio n ed o n

p . 233 o f my paper as bein g survivals from the Chon etes Be ds are

perhaps more correctly regarded as the con tinuation o f the n ormalfaun a , whereas the faun a asso ciated with P latyschisma he licites

is a specialized shallow- water on e . This p o in t n eeds furtherinvestigation .

II . NOTE ON THE CORRELATION TABLE (p . 169 )

This is practically iden tical with that already advo cated byBarro is

,Pruvo st

,an d Dubo is (op ; who approached the subj ect

from an en tirely differen t standpo in t— that o f _

the study o f the faun asin the North of Fran ce . My con clusio n as to the relation of the

1 Stamp , loc. cit. p p . 228—9 .

2 El le s 85 Slate r, Quart. Journ . Ge o l . So c . , vo l . lxii , 1906, p . 195 , Stamp ,

ibid vo l . lxxiv, 19 18 , p . 221, 19 19 .

1 68 L. Dudley Stamp— Limi t between

Gedin n ian of the Arden n es with the En glish Down ton ian 1 was

formed before seein g their pap er, o r kn owin g o f the successio n inNorth Fran ce , and it has been amp ly con firmed by the won derfulseries there exhibited .

III . WHERE SHOULD THE BOUNDARY BETWEEN. THE

SILURIAN AND DEVONIAN SYSTEMS BE PLACED’3

(1 ) PALE ONTOLOGICAL EVIDENCE .

The Silurian andDevon ian systems were origin ally described fromtheir developmen t in En glan d,

where there is n owhere a sup erp o sition o f typ ical marin e Devo n ian on typical marin e Silurian .

The later detailed classification o f the Upp er Silurian and

Down ton ian has been formed on the supp osition that theupp er limit of the Silurian co in cided with a chan ge o f faciesfrom marin e to lacustrin e— a truly un satisfactory basis for in tern ation al correlation .

The paleeon to logical affin ities o f the faun a o f the Gedin n i an are

briefly n o ted above . Tho se geo logists who have advo cated thep lacin g of the Gedin n ian in the Silurian have undoubtedly beencorrect in recogn izin g the clo se con n exion of Gedin n ian an d

Down ton ian .

3 The difficulties of co rrelation largely disapp earwhen Down ton ian is con sidered as Devon ian ,

sin ce the supp o sedSilurian character of the Gedin n ian lamellibran ch faun a can n o t becon sidered as of great imp ortan ce . Palaeon to logists are gen erallyagreed as to the un satisfactory n ature of lamellibran chs as zon alforms, and in any case our Silurian sp ecies are very imperfectlykn own .

In North Fran ce the p ercen tages o f Silurian an d Devoman speciesin each bed have been worked out

,an d o n this basis the summi t

o f the Silurian should be taken at the top o f the Grauwacke deDro court .In Britain it is n ecessary to rely prin cipally on fish remain s,which , with o n e or two excep tio n s , are first found in the LudlowBo n e - bed . The Down ton ian an d Lower Old Red San dston e are

un ited by several gen era an d even sp ecies o f Ostracoderms .

(2) STRATICRAPHICAL EVIDENCE .

The Silurian sea o f Upp er Ludlow times was of comparativelylimited exten t . In Lower Gedin n ian times on the co n tin en t o fEurop e the sea spread over a vast tract of coun try in theArden n es 4

1 Throughout this n o te the term Down ton ian is used in its re stricted

se n se , app ly in g on ly to beds above the ho rizon o f the Ludlow Bon e - bed .

2 Se e Evan s, GEOL. MAG . , Vo l . LVI, 19 19 , p . 549 .

3 Leriche ,

‘‘Po isson s fossiles da

.

Nord de la Fran ce Mem . So c . geo l . da

No rd, vo l . v ,1906, p p . 13—2 1 .

4 Compare South Devon an d Cornwal l , Green an d Sherborn , GEOL . MAG . ,

1913, p . 70 .

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'

L . Dudley Stamp— Lim-i t between

the greater part o f the presen t Bassin de Din an t— an dg ave rise towell - marked basal con glomerates and san dston es (Poudin gue deFepin and Arkose de Haybes) . The movemen t was isostatic inits n ature

,and was co in ciden t with a shallowin g o f the pre - existin g

Upper Ludlow sea in No rth - East Fran ce . A very similar iso staticmovemen t seems to be in dicated in South Wales as n oted o n thecorrelation table . Thus in North - East Fran ce, Shropshire , and

certain districts o f SouthWales,although there is a gradual tran sition

from the Upp er Ludlow to the shallower- water dep osits o f

Down ton ian age , the most widely spread disturban ce , heraldin g the “

adven t o f the Devon ian p eriod,o ccurs in Lower Gedin n ian an d early

Down ton ian times . The commen cemen t of this movemen t maypossibly be in dicated by the Ludlow Bon e - bed .

In Sco tlan d the Down to n ian ro cks 1are sometimes seen to rest

con formably on Upper Ludlow, with or without a co n glomerate atthe base ; but an imp ortan t tran sgression o f the sea is indicated,for examp le, in Kin cardin eshire ,2 where Down toman ro cks, con

formably overlain by Lower Old Red San dston e, rest on '

l Upp er

Cambrian . In the Southern Up lan ds there is sometimes a markeddiscordan ce (Pen tlan d Hills and Ayrshire) , and sometimes apparen tcon formity (Lan arkshire) , between the Lower Old Red Sandston ean d the Down ton ian . The fo ldin g in the district is so in timatelycon n ected with the vo lcan ic activity o f Old Red San dston e times,that the area must be con sidered in relation to o thers rather thanby itself.From the stan dpo in t o f physical geo logy , sure ly the on ly logical

view is to regard the Down ton ian as the commen cemen t o f theDevon ian Period . To regard it as Silurian is to admit the en ormousexten sio n “

o f the Silurian sea at the very en d of the period, almosteverywhere to be succeeded imp ercep tibly by Devon ian or Old

Red San dston e,the ro cks “

o f the latter havin g , except in specialcases

,n o n atural stratigraphical base .

. To this it may be obj ected that the UpperGedin n ian o fNorth EastFran ce and Belgium ,

as well as parts of the succeedin g Coblen tzian ,

are o f Old Red San dston e typ e , and are therefore to be regardedas markin g the close of a p eriod rather than as an in tegral part ofthe Devo n ian Period . Truly the rocks o f this age in the Arden n esare n ot rich in fossils

,an d co n sist frequen tly of san dston es , in dicatin g

shallow - water condition s un favourable to life . But litho logy isby n o mean s a sure indicatio n o f lacustrin e or true OldRed Sandston econdition s . The discovery o f marin e fo ssils. in the Down ton ian of

En glan d— in cludin g the Temeside Shales of Clun Forest— in rockswhich were regarded as typ ical o f Old Red San dsto n e, is paralleledi n Belgium in the work o f Dr . E . Asselbergs . This geo lo gist, well

1 Si lur ian Rocks , Scotlan d (Mem . Ge o l . 1899 , p p . 68—9 , p . 568

e t seq.

2 Camp be l l , The Ge o logy o f South Easte rn Kin cardin eshire Tran s.

Roy . So c . Edin vo l . xlviii , 19 13, p . 923.

Si lu r ian an d Devon ian Sy stems .

kn own fOr his work o n the Devon ian has traced fossiliferous marin ebands in the Lower Coblen tzian o f the South of Belgium (Bassind

’

Eife l ) ,1

and is o f the op in ion that the OldRed San dston e (lacustrin e)facies do es n ot exist at al l in the Arden n es . The existen ce o f shallowwater an d sparsely fossiliferous ro cks in the Upp er Gedin n ian an d

Lower Coblen tzian_

is o n ly the n atural con sequen ce o f the hugetran sgression an d atten dan t shallowin g o f the sea 1n LowerGedin n ian times, and can n o t be regarded as represen tin g a chan geseparatin g two p eriods— the Silurian and Devon ian .

(3) CONSIDERATIONS OF PRIORITY .

Murchiso n o rigin ally drew the lin e of division between his Si lurianand his Old Red San dston e systems in Shropshire just above . theLudlow Bo n e - bed . It was o n ly the occurren ce o f man y

- o f theUpp er Ludlow fossils in the Tileston es

'

Down ton CastleSan dston e) that in duced him to in clude the latter in the Silurian .

2

For reason s of priority it would be preferable to in clude the Bon eb ed still in the Silurian ,

but there is eviden ce to show that,bon e

beds tend to occur at the base rather than at the summit of systems .

The writer co nsiders the LudlowBo n e - bed as an organ ic basalcon glomerate markin g the base o f the Devon ian system .

IV. CONCLUSION.

The absen ce of a clearly defin ed limit between the Silurian and

Devo n ian in En gland has lon g been a great hindran ce to wo rkersboth here an d abroad . The result has been apparen t in recen t y earsin the so - called Gedin n ian problem i . e . as to .whether theGedin n ian is to be con sidered as Silurian o r Devon ian .

3 It is at

l east desirable that a statemen t o f our presen t kn owledge should bec learly outlin ed . After the publication of the detailed accoun t o fthe succession in North - East Fran ce

,an d also o f further work o n

the Down ton ian fish faun as of En glan d,

4 it is hop ed that the who lesubj ect‘will be treatedmore fully by Dr . Pierre Pruvo st andmyself.

1 Mem . de 1"In st. geo l . de l

’Un iv . de Louvain , vo l . 1, 19 13

2 S i luria,4th cd . ,

1867, p p . 134—5 .

'

3 Se e De Dorlodot, Bul l . Soc. be lge Geo l . , vo l . xxvi , 19 1 2 , Pro c . verb .

p p . 17—39 >62—5 ; An n . Soc . geo l . Be lgique , vo l . xxxix , 1 91 2 , pp . M 29 1

M S71 . Mail leux , Le texte exp l icatif du l évé geo l . de la p lan . de Couvin ,

1 912 (Serv . geo l . Be lg ique ) : Bul l . So c . be lge Geo l . , vo l . xxvi , 1 9 12 , Pro c; verb .

p . 139 . Fourmarier, An n . So c . geo l . Be lgique , vo l . xxxix, 19 12 , p . 233.

Leriche , Bu l l . Soc . be lg e Geo l . , vo l . x xv, 19 1 1 , Pro c . verb . p . 327 .

4 In di cated by Kin g 86 Lewis, Pro c . Birmin gham Nat. Hist. an d Phi l .So c. , vo l . x iv, 19 17, p . 90 .

1 72 t

l

Dr . F. R . Cowp er Reed

Carbo n ife ro us Fo ssils from Siam .

By F . R . COWPER REED M.A . , Sc.D. , F.G.S.

(Con cluded from p .

Athyris subti lita (Hall) . (Pl . II , Fig.

ONE intern al cast of the p edicle - valve of a sp ecies of Athyris

seems in distin guishable from A . subti lita Hall 1 which o ccurs inthe Carbo n iferous o f Belgium ,

2an d has recen tly been recorded .

frOm Eastern Yun n an .

3 The gen eral shap e an d n arrow mediansulcus

,the con cen tric sublame llose growth - ridges, an d small

,

p arallel den tal plates, are well seen in our sp ecimen .

Sp irifer (Reticularia) cf . lin eatus Martin .

The p eculiar an d characteristic orn amen tation of Sp . lin eatus is

found o n a fragmen t o f a crushed valve -

in the co llection . Thiswell - kn own sp ecies o ccurs In the Culm of Hagen ,

accordin g to

N as well as elsewhere .Camarop horia Sp . (Pl . II , Figs. 1 1 ,

There is the flatten ed impression an d the cast of the left half of thevalve o f a small brachiop od, p ossessin g characters which in di cate itsreferen ce to the genus Oamarop horia . The beak Is n o t preserved,

an d

it is doubtful if it i s the brachial or p edicle valve with which we haveto deal . The cardin al an gles are roun ded ,

there are 4—6 fain t,low,

“

rounded ribs on each side o f a median weak sinus, which alsobears two or three ribs, but the lateral p ortio n s o f the shell aredevo id o f ribs

,an d simp ly Show a few stro n g co n cen tric growth

ridge s . These extern al characters seem to suggest a comparisonwith 0 . Bunkeri (Ro emer) as interpreted by Ho lzapfel . 5 An o ther,but un crushed sp ecimen (Pl . II , Fig . 12) con sists o f the in tern alcast o f a p edicle - valve , 12 5 mm . lon g an d 15 mm . wide, whichShows the trian gular sp on dy lium .

Productus concen tricus Sarres - Kayser . (PI. 11 , Fig .

There is o n e brachial valve of a sp e cIe s o f Productus which seemsto co rresp ond precisely with the form described an d figured byKayser 6

as Pr. eon cen tricus Sarres, from the Rhen ish Culm . Our

sp ecimen ,which measures 9 mm . in width , Shows the orn amen t

and Shap e distin ctly , and is fairly well preserved . An o ther less1 Davidson , M on . Bri t. Foss . Brach , vo l . ii , p p . 18 , 86, 217, p l . 1, figs . 21—2

p l . xviii , fig s . 8—10 .

De Konin ck, Faun e Ga le . Carb. Be lg . , vo l . iv , p t. vi , p . 73, p l . xviii,.figs . 1 4 , 12 28 .

3 Man suy , op . cit . , vo l . 1, fasc . ii , p t. ii , 19 12 , p . 92 , p l . xvii , fig . 2 , p . 98

p l . xvii i , fig . .6 .

4 Nebe , Op . cit . , p . 447, t . x iv, fig . 14 .

5 Ho lzap fe l , op . cit . p . 65 , t . vii , fig . 8 .

b Kay ser, Jahrb. k. p reuss . geo l . Lan desan st” 1882 (for 1881 ) p . 83,/ t . iii ,

figs . 3 4

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1 74 Dr . F. R . Cowp er Reed

Chon etes afl . buchiana De Kon in ck . (Pl . II , Fig.

An o ther species o f Chon etes is represen ted by the in tern al casto f a p edicle - valve an d the in terior view o f the same valve . The

ribs,which are comparatively few (about twen ty to twen ty -f ive in

all ) , an d coarse, are equally an d widely spaced, an d show fain tlythrough the substan ce o f the shell, and the two pairs o f,muscle - scarsare distin ct . The valve is gent ly convex

,slightly flatten ed n ear the

cardin al an gles;which are rectan gular, an d the beak is small and incon sp icuous . There are several small

, short, cardin al sp in es alon gthe hin ge - lin e . The shell measures about 8 mm . in width and 5 mm .

in len gth . The sp ecies is probably allied to,if n ot iden tical wi th ,

Ch. buchian a De Kon .

1

Chon etes sp .

There is the cast an d impression o f ' the p edicle - valve of an o thersmall Ghon etes, which is di stin ct from that above described . It istran sversely subtrian gular an d fusiform in shape

,

‘ with . acutelypo in ted an d somewhat produced lateral an gles, and is widest alon gthe hin ge - lin e . The median p ortion of the valve 1s stro n gly co nvex,an d rises rather sudden ly from the depressed lateral p orti on s . Thecardin al an gles are p o in ted at about 45 to 60 degrees ; the beak isobtuse and small

, and scarcely pro j ects over the hi n ge - lin e . Thesurface o f the valve is covered with rather coarse, though small,roun ded riblets, about thirty - five to forty in n umber . The in tern alcast shows rather large and widely separated pustules arran ged inradial lin es , and there are traces of n arrow elon gated muscle - scars .

There are indicatio n s of the bases o f a few small cardin al sp in esalo n g the hin ge - lin e . Dimen sion s width

, 85 mm . len gth4 5 mm . The shap e o f our Shell recalls Lep tcen a convo luta Phill .from the Devon ian o f Croyde Bay , whi ch McCoy 3

records from theCarbon iferous o f Ireland . Loczy

’

s Ghon etes Fleminyi var . gobi ca,4

from the Carbon iferous of Chin a, may also be compared .

Proetus cf. coddon en sis Wo odward . (PI. 11, Fig .

Descrip tion .

— Pygidium tran sversely semicircular . Axis stron glyco nvex

,bro ad

, about o n e - third the width of the pygidium and

three fourths its len gth, comp osed o f seven complete ri n gs withn arrow

,lateral portio n s in distin ctly marked o ff by weak lon gitu

din al furrows ; tip blun tly'

p o in ted . Pleural lobes somewhat flatten ed,with four distin ct pleuree on each side (and traces of a fifth) , an d a

half-

p leura o n each fron t edge ; pleuree radi atin g , straight, extendin gn early to the margin o f pygidium,

successively decreasin g In stren gthan d len gth p osteriorly ,

with raised suban gular surface bearin ga fin e median furrow ; in terp leural furrows well marked . Fin e weakmarginal furrow, in distin ctly separatin g o ff a roun ded border.

1 De Kon in ck , A n im. Foss . Garb. Be lg . , 1842—51 , p . 208, p l . .x ii , figs. l a—l c.

2 Phillip s , Pa loeon t. Foss . Cornw. Dev. , p . 57, p l . xxiv,fig . 96 .

3 McCoy , Syn . Carb. Foss . Ire l . , p . 1 19 .

4 Loczy ,Op . cit. , p . 77 , t . iii , fig , 14 , text- fig . 15 .

Carboniferou s Fossi ls fromSiam . 1 75

Surface of pygidium very fin ely granulated . Dimen sion s : “len gth ,5 mm . ;width, 8 5 mm.

Remarks — Two pygidia o ccur on opposite sides of the samepiece o f

,ro ck, on e with the shell preserved an d the o ther in the

con dition o f a ho llow impressio n . These were iden tified byProfessor Hughes as Proetus . The very short pygidium an d smallnumber of

'

segmen ts of which it is comp osed seem to necessitatethe referen ce of these specimen s to this gen us rather than to Phi llip siaor Grifiitlzides, and we may compare it with the Lower Culm sp ecies ,Proetus sp . a

‘an d Pr . coddon en sis Wo odw .

2from North Devon .

Pr. p ostcarbon arius G‘remme llaro

,

3 from the Sosio Limesto n e o f

Sicily , seems also to be allied to our form . It is un doubtedly distin ctfrom the sp ecies Proetus e llip ticus Man suy ,

4 from the Dinan tianof Eastern Yun n an ,

which seems to be the on ly species o f the genuspreviously recorded from the Carbon iferous of South - Eastern Asia .

The o ccurren ce of this typ ically Devon ian an d Silurian genus inthese Siamese beds is a token o f their low stratigraphical p o sitio nin the Carbon iferous . Apart from _the Devon shire sp ecies, the on lyCarbon iferous represen tatives o n the Co n tin en t are Pr. (Decken ella )angustigenatus Leyh , and Pr . (D) hop ensis Leyh , from the

Po sidon ien schiefer o f the n eighbourho od o f Hof.5

Pki llip sia aff. si lesiaca'

Scup in . (Pl . II, Fig .

On e small imp erfect middle shield o ccurs in the co llection,

measurin g between 3 and 4 mm . in len gth, but there is sufficien tpreserved to decide its referen ce to the genus Phi llip sia ,

though thespecies can n o t be determi n ed .

’ The glabella is semi - oval, somewhatelon gated, widen in g slightly posteriorly ,

with n early straight sides,an d it con sists prin cipally of a large somewhat swo llen median lobeoverhan gin g the front en d, with a

’

pair of very short lateral , n earlyhorizo n tal furrows inden tin g its sides an d markin g o ff in comp letelya pair o fvery small lateral lobes, which are boun ded p osteriorly by .the

deep er and stron ger short oblique basal furrows n ot reachin g themesoo ccip ital furrow The basal lobes are small

,swo llen ,

subtubercular,an d subtrian gular, an d they are widely separated from each o therby about thr ee times their width . The eye - lobes are lon g, n arrow,and rounded

,an d are closely pressed again st the sides o f the

glabella, reachin g from a p o in t about half its len gth to behind thebasal lateral furrows . The fixed cheek behin d them seems to bevery small

,but this part is n o t well preserved . Several sp ecies o f

this genus have been described from the Lower Culm n ear Ho f 6 an d

from the Lower Carbon iferous of Silesia,

an d ours esp ecially

fi

1

Wo odward, Quart. Joum . Ge o l . So c. , vo l . 11, 1895, p . 648, p l . xxvii i,gs . 7a .

2_

Wo odward , GEOL . MAG Dec . IV,Vo l . IX , 1902, p . 483,PI. XX ,Figs . 5—1 1 .

3 Frech , Leth. Geogn . I, Pa lo ma , Bd . ii , Lief. iv, 1902 , p . 506, t . 596, fig . 5 .

4 Man suy , op . cit . , vo l . i , fasc . ii , p t. ii , 19 12 , p . 85 , p l . xvi , fig . 2 .

5 Leyh, Z eitschr. cl out. geo l . Gesel l . , xlix , 1897, pp . 522 , 524 , t. xvii , figs . 1 , 2 .

6 Ibid ., pp . 526—7

, t . xvii , figs . 3, 4 .

1 76 Dr . F. R . Cowp er Reed

resembles Pk. si lesiaca Scup in .

l On e o fNebe’s figures 2 o f a glabellaattributed to his sp ecies Phi llip sia westpkalica, which do es n ot showan y lateral furrows, also seems somewhat to resemble our sp ecimen .

Cythere s .p

A mmute oval ostracod, measurin g less than 2 mm . l n len gth ,an d with rather po in ted extremities

,o ccurs in the co llection ,

but

is n ot sufficien tly Well preserved for a descriptio n,but it may be

referred to the gen us Cytkere .

Cladockon us cf. Miche lin i (Edwards Haime ) . (PI. 11, Fig .

Three n arrow, elon gated, tubular corallites, expan din g slightlyat their fun n el - shaped mouths an d conn ected i n a lon gitudin allin ear man n er, with a slight altern ate direction to the right an dleft

,may be compared without hesitation to the Cladochonus

Michelin i . Edw. H.,

'

as figured by Kayser 3 from the Rhen ishCulm . This species also o ccurs in the Coddon Hill Beds o f

Barn stap le . 4 It seems closely similar in mode of growth to Cl .Schluteri Ho lzapfel,5 from the Rhen ish Devonian . In our specimenfrom Siam the to tal len gth o f the corallites is about 30 mm .

,the

successive corallites measurin g respectively 11 mm .

,13mm.

,and

9 mm .

LIST OF FOSSILS FROM KUAN LIN

Pron orites aff. cyclo lobus

Pro lecan ites sp .

Nomismoceras sp .

Glyp hiocem‘

s sp .

Pleurotomaria (Mourlon ia) aff. con ica Phill .Euomp halus cf. subcircu laris Man suy .

He lmin thochiton cf. p rison s (Miin ster) .Paral lelodon afif. corrugatus (DeEdmon dia sp .

A l lorisma sp .

Protosckizodus sp .

P osidon omya Beckeri Bron n , var. siamen sis n ov .

cf . radiator, Wh . Hin d .

Pseudamusium cf. p roetenue (Von Ko en en ) .Aviculop ecten cf. den sistriaActin op teria sp .

Athyris subti l ita Hal l .

Sp irifer cf. l i n eatus Mart.

Camarop koria sp .

Productus con cen tr icus Sarre s - Kay s.

lcevip un ctatus Sarres .

cf. p licatus Sarre s .

1 Scup in , ibid.,lii, 1900, p . 8 , t . 1, figs . 1 3.

2 Nebe , op . cit . p . 474 , t . x ii , fig . 4 .

fig

3geo l . Lan descmst” 1882 (for p . 85, t . iii ,

01. 19 .

O

4 Hin de Fo x , Quart . Journ . Ge o l . So c. , vo l . 11, 1895 , p . 644 , p l . xxvii i ,fi gs . 19 , 19a .

5 Ho l zap fe l , Abh. k. p reuss . geo l . Lan desan st. , N.F Heft xvi, 1895, p . 305,

t . x i i, figs . 1 , 2 , 7

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1 78_

Revi ews— Block‘

Mo’

un ta i n s i n New Z ea lan d .

PLATE II.

FIG .

1 . Pron orites aff . cyclo lobus 15.

2 . Pleurotomaria (Mourlon ia ) afi . con ica Phil l . l é.

3. Euomp ha lus cf. subcircu laris Man suy . x 2 .

4 . Helmin thockiton cf. p riscas (Miin st) i

x 2 .

5 . Para llelodon aff. corrugatus De Kon . x 156 . Edmon dia sp . x 2 .

7 . Pos idon omya Beeheri Bron n , var . szamen sis n ov .

8 . Pseudamusium cf. p raeten ue (Von Koen ) x 15.9 . A rticulop ecten cf. den sistria

10 . A thyris swbti lita, Hal l . x 151 1 . Camarép koria sp . x 2 .

12 . Dl tto . x

13. Productus con cen tricus Sarre s -Kay ser. x 3.

14 . Ice vip un ctatus Sarre s. x 3.

15 . C'hon etes cf. rectisp in a, Von Ko en . x 2 .

aif . buchian a De Ko n . x 25.

17 . Proetus cf. coddon en sis Wo odw. x 3.

18 . Phi llip sia aff. si lesiaca Scup in . x 5 .

19 . Cladochon us cf. M ichelin i Edw. Haime .

REVIEWS.

BLOCK MOUNTAINS IN NEw ZEALAND . By C. A . COTTON . AmerJourn . Sci . , vo l . xliv, 19 17, pp . 249—93.

THIS pamphlet deals more especially with the blo ck moun tain sof Otago , a district in which the blo ck featur es are unusually

well preserved . The up land surfaces in Cen tral an d Eastern Otagohave been described by bo th Park an d Marshall as portio n s of

a dislo cated plain of ero sion,termed a pen eplain ,

the presen t relief'

bein g regarded as the work Of ero sio nThe writer’s hypothesis, however, invo lves p lan ation ,

sedimen

tation,and deformation , fo llowed by a p eriod Of erosion , dur in g

which larger areas of the p lan ed undermass have been re - exp o sedby strippin g o f the cover . It “ is quite p ossible that some of theeroded surface o f the undermass has n ever been covered, an d therefore forms a true pen ep lain ; but, to the writer’s mind, con clusiveeviden ce as to the former wide exten sion o f an overmass is affordedby the o ccasion al preservatio n o f small outliers o f the cover o n theup lan d p lateaus ; by wide distribution of the sarsen ston esderived from the cemen ted quartz grit and by the man n er in whichp lan ed surfaces of the Older rocks emerge from un der brown coal.strata as well as quartz grits with the same in clin ation .

Stress is laid o n the fact that fault scarps fo rm the boundarieso f a number of blocks in Cen tral Otago , and sufficien t eviden ce offaultin g is furn ished by the attitude of the coverin g strata at the

bases Of the scarp s . The con clusion arrived at is that the reli efisvery largely— almost en tirely— due to recen t differen tial movemen t.Of crust blo cks .

H. V. S.

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1 80 Revi ews— Mar i n e Bor in g A n ima ls

n o ticed in o ther districts durin g the last decade . By early -

geo logiststhis '

close gen etic con n exio n was n ot credited, but its accep tan cehas led to the enun ciation o f theories which have y et to be develop edo n physico - chemical lin es as a bran ch of the p etrogen esis . There isn o field of research which affo rds such scop e for o rigin al workas the origin of lodes in their con n exio n with a con so lidatin g magma

,

an d particularly this questio n of the defin ite o rder o f arrival of themin erals as an accesso ry fun ction Of it . As a who le the mo n ographis a comp lete treatise o n the o ccurren ce an d productio n Of tin ore

as far as it is p o ssible to make it in a fewpages, and it is the bestresumé Of the subj ect y et published,

'

the brief geo logical accoun tsbein g particularly go od . D . A .

“

MACALISTER .

MARINE BORING ANIMALS INJURIOUS TO SUBMERGED STRUCTURES .

By W. T .

'

CALMAN . British Museum (Natural History ) .Eco n omic Series

,NO . 10 . Lon don ,

1919 . Price 18 .

THIS wo rk, issued as a guide to an exhibit in the British Museumo f the more imp ortan t marin e an imals which are so destructive

to timber an d ston e,will be o f co n siderable in terest to geo logists .

Of the Mo lluscs which bo re in to wo od a_

ful l and valuable acco un t18 glven o f the shipwormTeredo n avalis

,in which the borin g is don e

by mean s Of rows Of fin e sharp—p o in ted teeth o n the fro n t Of thevalves . Briefmen tion ismade o f o ther wo od- borin g lamellibran chsPholas

,Martesia ,

Xylophaga . Next in imp ortan ce to the shipwormas a destroy er -

o f timber is the small Isop od Crustacean ,kn own as

the Gribble (Limn oria lignorum) o ther Crustacea which bore in towo od are the Amphip od Chelura terebran s an d the Isop od Spkceromaterebran s .

An imals which bore in to ro cks are more n umerous than tho sewhich bore in to wo od,

an d in clude Spon ges, Echin oderms, Wo rms

,

Mo lluscs, and Crustacea . Pho las is believed to make borin gsmain ly by the raspin g actio n o f the shell which is provided withrows of sp in es or teeth towards the fron t edges: Petricola

joho lacl iformis, although belon gin g to quite a differen t family (theVen eridae) , is remarkable fo r the close resemblan ce o f its shell toPho las candida . LitkOp li aga (Lithodomus) bores in calcareous ro cksby chemical mean s , an acid secretion bein g formed by a glandin the man tle . Saxicava rugosa is foun d main ly in limesto n es,an d the borin g i s probably effected by chemical mean s . The

prin cipal Crustacean which bores in to ro cks is the Isop od Spkceromaquoyan a ,

found o n the coasts Of Australia an d New Zealand, whereit burrows in soft san dston e an d c layston e . Other ro ck - borin gan imals described are the Po lychaete worm Po lydora an d the Sp on geClion a ce lata .

In con n exion with rock - borin g organ isms atten tion may becalled to a recen t pap er by Pro fessor T . J . Jehu ,

dealin g with thesubj ect from the p o in t o f view o f coast erosion (Scottish Geogr .

Journ . ,xxxiv

,January ,

Revi ews— Han dbook of Mi n era logy ,etc.

HANDBOOK OF MINERALOGY ,BLOWPIPE ANALYSIS

, AND'

GEOMETRICAL CRYSTALLOGRAPHY . By G. MONTAGUE BUTLER ,

E .M.,Director Arizon a Bureau ofMin es . pp . vi 311 , iv 80,

viii 155 . New Yo rk Wiley 85 Son . 1918 .

THIS bo ok is in reality three bo oks boun d in on e vo lume, eachpart bein g separately paged an d havin g its own title - page

and in dex . It professes to be a n o tebo ok for use in the field, andfor this purpose the first two parts, o n the physical characteristicso f min erals and blowp ip e an alysis, are very well adapted the bo okis small , an d will go in to a n ot very large po cket ; the prin tin g isclear

,an d the description s are short an d to the p o in t The on ly

exception s that may be taken are to the pho tographic illustration s,which are o n to o small a Scale to show to an y advan tage , an d tothe determin ative tables , who se use , in their presen t fo rm,

seemsrather cumbrous. In the last section , on crystallography ,

however,to o much relian ce has been p laced on description s un accompan iedby figures , with co n sequen t loss o f clarity ; and in addition theuse Of Nauman n symbo ls, to the en tire exclusio n Of the Millersystem, would app ear to be a mistake, in view Of the very wide useo f the latter system .

THE PHOSPHATE DEPOSITS OF SOUTH AUSTRALIA . By R . LOCKHART JACK . pp . 136 . Bull . No . 7, Parts i an d i i . Geo l .Survey Of South Australia, 19 19 .

ME idea Of the impo rtan ce Of the South Australian phosphatedep osits may be gathered from the fact that in 1916 on ly

ton s Of crude mi n eral pho sphate were _produced, Of which ton swere valued, after grindin g , at £3 12s . 7cl . a ton . The to tal amoun to f phosphate ro ck produced by the Co lon y up to the en d Of 1918 is

given as ton s, valued at In addition to calciumpho sphate ro ck, “ large bodies o f pho sphate o f alumi n a

‘

ex ist at

St . John ’

s,

”

n ear Adelaide,but the material is n ot acceptable to

the manufacturers o f sup erpho sphate , an d the State regards itas worthless . Part i gives accoun ts o f the natural o ccurren ce an dmethods of dressin g the material and preparin g it for the market , aswell as its use on South Australian land . Part ii con sists o f 90 pagesdevo ted to Reports on Individual Dep osits and con tain s man y

p lan s of workin gs an d prosp ects an d a few plates from photographs .

The fo llowin g n o tes o n the geo logical occurren ce are taken fromthe Bulletin .

Guan o — With the excep tion Of three places o n_the ,main lan d,

where cave - guan o o ccurs , deposits o f guan o are on ly foun d on theislan ds or coasts, but these app ear to ,

have been worked out . Thebulk o f the material con tain ed from 25 to 42 p er cen t of calciumphosphate . Accordin g to a report by the late F

”

. R . George in 1902a con siderable quan tity of guan o was removed from an islan d inCoffin

’

s Bay ,where it was mixed with sand

,broken sea - shells,

1 8 2 Revi ews— Phosp hate Dep osits“

of South Austra lia .

and vegetable matter,and in co llectin g this ho les and cavities in

the underly in g limeston es were fo llowed down for the guan o . At

10 feet phosphatic bo n e - breccias were en coun tered in the cavities .

Rock-

p hosp hata— The deposits of the main lan d are found 1n

asso ciation with metamorphosed Cambrian or pre- Cambrian lime

ston es or in the adjacen t argillaceous sedimen ts . The author is insome doubt as to whether the phosphate with which the limeston esare asso ciated is a con temp oran eous dep osit, con cen trated by thewithdrawal o f calcium carbon ate in so lution from phosphaticlimeston e

, or whether the phosphate has been in troduced from someextran eous source at a later date as a metasomatic rep lacemen t ofthe marmorized limeston es an d calcareous slate . In their lo cationamon g the steeply in clin ed sedimen tary beds the bodies are gen erallyclose to the limesto n es but o thers are found in clay - filled p o cketsin the strike of the limeston e beds . Their p osition suggests derivationfrom the eroded portion s Of the limesto n es , an d that precip itation Of

the phosphate by rep lacemen t to ok p lace either on the remain in glimeston e o r in calcareous slate from which the bulk o f the carbon atehas been removed,

the resultin g ro ck bein g a pho sphate with a highin so luble con ten t . Metasomatic rep lacemen t is indicated by thepresen ce Of Older vein s Of quartz , surrounded by pho sphateAn o ther feature indicatin g metasomatism is the silicificatio n of

certain beds at some o f the depo sits to form a chert - like blackto brown ish -

y ellow ro ck con tain in g a little pho sphate, which is“ frequen tly brecciated an d con torted in places, an d is foun d em

bedded in the phosphate ro ck . White to green ish sub - tran slucen t,stalactitic

, ren iform,

an d mammillary phosphate is common ,

o ccurrin g as coatin gs Of vughs , and who lly or partly surroun din gmasses of rock - pho sphate , an d is clearly secondary to the main mass

o f the ro ck in its order o f dep o sition . Bo th limon ite and

man gan ese oxide are almost in variably asso ciated wi th the pho sphatero ck . It is probable that in the rep lacemen t an d so lutio n Of therock con tain in g the phosphate dep osits , the iro n set free has a

tenden cy to segregate at the surface . ” This theo ry in dicatessubsequen t replacemen t, and the autho r go es o n to describe theclose asso ciation of the dep o sits as a who le with Tertiary gravelswhich overlie the dep osits . Where the latter have been erodedthe dep o sits o f pho sphate do n ot exist . He asso ciates the pro cessOf metasomatism with pre - Tertiary drain age, an d the destructiono f all the previously existin g dep o sits n ot pro tected by the Tertiarygravels to p ost - Tertiary den udation . This imp lies that the dep ositsdo n ot extend to great dep th , but they have been proved to dep thso f 1 10 feet . He p o in ts out the absen ce Of an y eviden ce as to thetrue age o f the pho sphatizatio n .

Ap atite .

— This o ccurs at Mo on ta Wallaro o ,and BalmacoOta,

in p egmatites Of p re- Cambrian age In a vein n ear Balmaco ota

Sp rin g the apatite makes up 40 p er cen t o f two vein s aggregatin g5 feet in thickn ess .

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'1 84 Revi ews—Su es? as Pa loeon tbl opi st.

formed by oxidatio n and sup ergen e en richmen t are n ative go ld and

silver, argen tite , po lybasite , pyrargyrite, Silver halo ids , malachite ,zin c Silicate

,with carbon ates

,quartz , chalcedon y , barytes, gypsum,

etc . An in terestin g feature IS the eviden ce that has been found Of

the existen ce of o n e o r more an cien t p eriods o f denudation an d

o xidatio n,at horizo n s n ow buried under subsequen t dep osits . The

o re - vein s are regarded as rep lacemen ts Of the vo lcani c coun tryro ck

,n ow called the Mispah trachyte , an d extendin g down in to the

un derlyin gu rhyo litic series

,bo th bein g of Tertiary age . In man y

places the geo logical evidence is favourable to the persistence o frich primary silver o res to depths co n siderably greater than an y

y et reached,though hot ascen din g waters in the deep er workin gs

may prove troublesome . It may be n oted that the o ccurren ce o fsuch min erals as pyrargyrite , p o lybasite , an d stephan ite In a primaryzon e is unusual .While n ot pretendin g to a high standard o f culture in deadlan guages, the reviewer ven tures to en ter a vigorous pro test again stthe emp loymen t of such a barbarism as the word supergen ehalf Latin and half Greek . This is o n a par with that j ourn alistichorror, hypersen sitive . Surely An glo - Saxon

,or

,at worst, go od

Latin terms can be found fo r such a simp le idea as is here impli ed .

What is the matter with secondary R . H. R .

SUESS As PALZEONTOLOGIST .

N the n umber o f the Revue Critique cl e Paléozoo logie fo r Jan uaryApril , 19 19 , which has just come to han d,

M. G. F . Do llfus hasan excellen t article o n the comp letion Of the Fren ch edition o f

Das An tlitz der Erde .. In it he discusses the palaeon to logical

work of Suess , an d shows how it'

gradually led him on to thosewider tecton ic studies fo r which

,in deed

,it formed the eviden ce an d

the foundatio n .

It may be men tion ed that the price of M. Co ssman n’

s usefulRevue has been raised to 12 fran cs p er an n um .

SOUTH AUSTRALIA DEPARTMENT OF MINES,MINING REVIEW NO . 30 .

pp . 56 . Adelaide, 1919 .

HIS rep ort con tain s statistics con cern in g the min in g in dustryo f the State for the half-

y ear en din g Jun e 30 , 19 19 , and a

n umber o f Sp ecial rep orts o n p o in ts o f i n terest . The mo st n o teworthy feature Of the p eriod un der revi ew was the dislocation o f

the copp er industry ,leadin g to the cessatio n o f smeltin g atWallaro o ,

and almost comp lete stoppage of productio n . The developmen tOf resources Of n on - metals con tinues to p rogress , an d reports are

p rin ted o n dep o sits o f bary tes, whitin g , graphite , an d asbesto s .

The productio n Of iron ore at Iron Kn ob has n ow reached thesatisfactory figure Of about ton s p er day . The body o f man

gan iferous iron o re is n ow exp o sed in two Op en workin gs to a depth “o f 100 feet

, and the reserves are eviden tly very large . An in terestin g

Revi ews— Plag i oclase - n e'

p he l in e Gran i toi ol Rocks 1 85

accoun t is given Of work carried out by the Wallaro o and Mo on taMin in g an d Smeltin g Compan y ,

Ltd .

, for_ the welfare of their

emp loy ees, which is o f a mo st elabo rate an d well - organ ized n ature,

an d co n ditio n s there app ear to be ideal .

THE CLASSIFICATION OF THE PLAGIOCLASE - NEPHELINE GRANITOID

ROCKS . By A .

'

LACROIX . Comptes Rendus, t . 170 , 1920, p . 20'

HE terms essexite an d theralite have suffered somewhat from lackof defin itio n an d discrimin ation in their use . Rosen busch

suggested the term theralite for~p lagioclase - n ephelin e ro cks o f

p luton ic habit, and cho se as the origin al typ e a rock from the CrazyMoun tain s

,Mon tan a ,

in which plagio clase was stated to be presen t .This was a mistake , as the ro ck proved to be a Shonkin ite , and

recogn izin g this Ro s'en busch afterwards to ok the unequivo cal

theralite o f Duppau, Bohemia,as

“ the typ e examp le . Lacro ix ,however

, prop osed in 1902 to use theralite for melan o cratic alkalisy en ites . He admits that with o ther petro logists he has appliedthe term in co n sisten tly ,

and in an in structive paper he n ow attemptsto put this group o f rocks in order on ce an d for all .The term theralite he reserves for meso cratic ro c

'ks which differfrom essex ites in havin g a smaller -

proportion o

'

f p o tash - felspars(o ften reduced to a man tle borderin g the p lagio clase crystals) , andin gen eral a higher ratio Of n ephelin e to felspars . In essex ites , as

in the typ e - ro ck Of Salem Neck,there is a n otable quan tity of

o rtho clase or soda - ortho clase in terstitial n ephelin e may be presen t,an d horn blen de is a con stan t ferromagn esian con stituen t .From the theralites prop er Lacro ix separates two types in whichthe n epheline - felspar ratio is lower an d the p lagioclase morecalcic than in the n o rmal members o f the group . Lusclacl ite , On e o f

these typ es, is characterized by the gen eral absen ce of horn blen dean d the presen ce o f Olivin e an d often of bio tite . The Crawfordjohnessexite is a British examp le , and Tyrrell’s Icy/ lite is regarded as a

melan ocratic facies . The o ther typ e , beron alrite , is characterizedby the presen ce of elon gated crystals of brown horn blende asso ciatedwith titan iferous augite . The mon trealite o fMon t - Royal is a coarsegrain ed melan o cratic variety . Theralitic rocks less rich in alkaliesthan those already men tio n ed are the mareugites, which are furthercharacterized by h

'

auyn e , an d which vary from highly felspathicto almo st ho lome lan o cratic typ es .

Two ro cks are con sidered as heteromorphic forms o f beron drite ,sin ce they differ essen tially from the latter in min eral compo sitionbut n ot in chemical comp o sition . In mafrai te n ephelin e fails toapp ear, its con stituen ts being presen t in an alumin ous soda

amphibo le . In fasin ite titan iferous augite con tain s the mi ssin gmi n eral , which l n this case is p lagio clase . Fasin ite, though com

p osed essen tially o f titan iferous augite an d n ephelin e , thus differsfrom ij o lite in con tain in g abun dan t n ormative p lagio clase .Bekinkin ite is n ot dissimilar in chemical comp osition from fasin ite

1 86 Rep orts (faProceedi n gsfi Eolin burgh Geo log i ca l Soci ety .

excep t in its greater con ten t o f water . The min erals, however, aremain ly horn blende and an alcite .Corresp on din g to the soda - series co n sidered above , few leucite

ro cks are kn own,the gran ito id typ es so far recogn ized bein g restricted

to certain ej ected blo cks from the tuffs OfMon te Somma . Pug lian ite

is main ly comp osed o f leucite,an orthite

,and augite , an d is the

homo logue o f . mareugite . A heteromorphic fo rm Of puglian ite ,kn own as sebastian ite , is main ly comp osed o f biotite , an orthite, andaugite , an d co rresp on ds to mafra

‘

ite in the soda series .

The pap er con cludes with a series o f thirty - three an alyses ,in cludin g several which app ear for the first time .

ARTHUR HOLMES .

REPORTS AND PROCEEDINGS.

EDINBURGH GEOLOGICAL SOCIETY .

February 18, 1920 .

— Mr . E . B . Bailey ,M.C. , B .A .

,F.G.S ,

Presiden t,in the chair .

On the Vascular Plan ts o f the Chert Ban d of Rhyn ie , Aberdeen~shire . ” By Dr . Kidston

,LL .D .

,F.R .S Presiden t of the Glasgow

Geo lo gical So ciety .

The remain s of four Vascular p lan ts have been discovered in thesilicified p eat bed at Rhyn ie , Aberdeen shire . These are— Rhyn iamajor K . 85 L . , R. Gwyn n e

—Vaughan i K . 85 L . ,Horn ea

' Lign ieri

K . L .

,and Asteroxylon Mackici K . L . Though their remain s

o ccur in mo re or less fragmen tary con dition ,it has been possible

in the case of the first three,to obtain an almo st comp lete kn owledge

o f their morpho lo gy and an atomy . In regard to Asteroxylon Machiei

the vegetative regio n is kn own with co n siderable fulln ess, but thesp o ran gia, which we believe to belon g to this species , have n ot beenfoun d in o rgan ic co n n exion with its stem o r bran ches

,so there is an

elemen t Of doubt on its fertile_

co n ditio n . All these vascular plan tsapp ear to have grown in a gregarious man n er . A brief descrip tio no f each may n ow be given .

Rhyn ia major was ro o tless an d had - n o leaves . It con sisted Of a

system o f dichotomously bran ched cy l in drical stems,which aro se

from un dergroun d bran ched rhizomes,that were attached to the

p eaty so il by n umerous n on - sep tate rhizo ids . The p lan t was largerthan R. Gwyn n e Vaughan

/i,

'

an d probably attain ed a height o f

40—50 cm . There is,however

,n o clear in formatio n o n this p o in t .

The rhizome is comp o sed Of delicate tissue with a vascular bundlewhich dicho tomized

,an d some o f its bran ches grew upwards as

taperin g aerial stems . The stem bore n o leaves or lateral pro j ectio n s .

It con sisted o f a wide co rtex comp osed o f a n arrow outer, an d a

wide, more delicate , in n er zon e . The vascular system con sisted o f

simple cy lin drical stele, formed Of a so lid strand of tracheides ,with n o distin ctio n Of protoxy lem an d metaxy lem . Surroun din gthe xy lem was a broad zo n e Of phlo em .

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1 88 Rep orts (12 Proceedi n gs— Mi'

n era log i ca l Somety .

-MINERALOGICAL SOCIETY .

January 20,1920 .

— Dr . A . ,E . H. Tutton ,

Past Presiden t,in the chair .

Dr . E. S. Simpso n : Gearksutite at Gin gin ,Western Australia .

The min eral,which occurs in Cretaceous green sand, is co n sidered

to have a comp osition corresp on din g to the formula CaF2 AlF(OH)2H20 ,

an d to have origin ated from the in teraction in situ o f

fluorapatite , gibbsite , and carbon ated water .

— C. E . Barrs : Fibroferrite from Cyprus .

”

An aly sis o f material from Skourio tissa,Cyprus , gave

'the fo llowin g result : Ec2O3 31 36, SO3 30 95, H2O (bydifferen ce) in so luble —Dr . G. T . Prior : On theClassification Of Meteorites .

”

For purp oses o f the classification o fmeteoritesthe sign ifican ce i s p o in ted out of the chemical composition of then ickel - 1ro n and the magn esium silicates . In the case Of meteoriciron s the structural features

,as revealed by etchin g , are shown to

be closely related to the conten t o f n ickel . In meteoric ston es theprop ortio n o f magn esia to ferrous oxide In the magn esium silicatesvari es directly with the prop ortion of 1ron to n ickel l n the n ickeliron . On these prin cip les the four classes of meteorites, V iz . iron s ,ston y - iro n s

,chon drites

,an d achondrites , can be divided in to in ter

related group s . The three groups Of chon drites are distin gui shedas en statite - cho n drites

,bron zite—chon drites , an d hypersthen e

chondrites,accordin g to the chemical comp osition of the pyroxen e .

The achon drites are divided in to corresp on ding groups Of en statiteachon drites

,bron zite (- augite) - acho ndrites , an d hyp ersthen e

achon drites,while a fourth group is added richerin lime (an d mostly

also in alumin a)'

than the cho n drites . To avo id con fusion owin g toBrezin a

’

s misuse o f the term chladn ite,the en statite - achon drites,

comprisin g Aubres, Bustee, and Bishopville , are called Aubrites,while for the hyp ersthen e achon drites (Shalka ,

etc . ) a reversion ismade to Tschermak

’

s o rigin al n ame of dio gen ite —A F . Hallimond :

On Torbern ite . In co n tinuation Of the author’s previous worka series o f weighin gs were made o n Gun n islake material held overvarious con cen tration s o f sulphuric acid . Dehydration .did n ot

o ccur at the pressure required,an d o n ly to ok place slowly over stron g

acid in a p eriod o f man y mon ths . It is clear that this min eralcan n o t be iden tical with o rdin ary torbern ite . The refractive indexagrees with that found for an abn ormal torbern ite by N. L . Bowen .

Normal torbern ite has the den sity 3 22 an d mean in dex 1 585,while for artificial metatorbern ite an d for the

’Gun n islake min eralthe den sity is 3 68 an d the index 1 624 . An approximate readin gy ielded for Gun n islake crystals 0 a 22 8 1 . The basal p lan es;o f the two forms are o f the same dimen sion an d the vo lume chan gedue to the additio n o f 4H2O 1s born e by an in crease in the verticalaxis . The den sity Of the

2

water o f crystallization is 1 2, a valuecommo n in hydrated salts

,while the refractive p ower is equal to

that for liquid water .

Rep orts (63 Pr oceedi n g s— Geo log i sts

’

A ssoci ati on . 1 89

GEOLOGISTS’

ASSOCIATION .

January 2 , 1920 .

The Liassic Ro cks of the Cardiff District . By A . E. Trueman,

D .Sc . , F.G.S.

The greater part o f South Glamo rgan shire , from Cardiff westwardsto beyond Bridgend, con sists of Lower Liassic ro cks (Hettan gian

and Lower .

-Sin emurian ) , which are well seen in some 20 miles of

magn ificen t cliff section s . On ly meagre descriptio n s Of these ro ckshave been hitherto published . A detailed study has been undertaken ,

first because n owhere else in this Coun try are such co n tinuous section sOf these ro cks available, an d secondly because the n ormal dep ositscon sistin g Of limeston es an d Shales seen n ear Cardiff, when tracedwestwards, pass in to littoral facies or massive limeston es and

con glomerates . In the presen t commun icatio n an accoun t of then ormal Liassic ro cks of the Cardiff district is given ,

as this will forma basis for the correlation o f the modified 'deposits further west .The Liassic ro cks n ear Cardiff o ccur in several outliers

,the chief

bein g tho se at Pen arth,Lavern o ck, Leckwith, and St . Fagan s ;

the sequen ce in the two former 1s clearly,seen in cliff section s, and

in those localities there exists an almo st comp lete tran sition fromKeup er to L ower Lias, so that they have become classical localitiesfor the study o f the Rhaetic beds . In the clifls at Lavern o ck, wherethe Liassic sequen ce has been mo st fully examin ed, the ro cks are

seen to form .a gen tle syn clin e, an d sin ce many o f the limeston ebands form exten sive reefs on the beach it is '

an easy matter to co llectfossils In p lace .The gen eral sequen ce at Lavern ock and in the n eighbourin g

outliers Is as fo llows : a

Fee t.

Nodular l imeston e s an d shale s , main l y an gu latus zon e , about 40Lave rn ock Shale s , an gulatus zon e , with Waehn eroceras

in the lower portion

Nodular l ime sto n e s an d shale s with Ca loceras cf .

John ston i

Lime ston e s an d shale s with P si loceras cf . p l 'an orbe'

Lime ston es and shale s (Ostrea beds)White Lias

LIVERPOOL GEOLOGICAL SOCIETY .

February 10 1920 .

— Mr:W. T . Walker,E.Sc .

,F.G S. , Presiden t,

in the chair .

The fo llowin g pap er was read : Dumb - bell Islan ds an dPen i n sulaso n the Coast o f South Chin a .

”

By Walter Schofie ld,M.A .

The pap er records Observation s made durin g a residen ce o f severaly ears in Hon g

- Kon g, in the n eighbo urho od Of which the dumbbell island and pen in sula— a

_physical feature Of the coast o f

South Chin a which attracts atten tio n by its frequen cy— are

e sp ecially commo n .

A dumb bell may be defin ed as two land areas con n ected

1 90 Corr esp on den ce— E . H. Cun n i n gham Cra ig .

by a relatively n arrow isthmus o f san d which is n ever belowhighwater mark in an y part Of its len gth . The Size '

Oi the areas Of lan dmay vary to an y exten t, but the highest p o in ts in bo th must risehigher above sea - level than an y part o f the isthmus . The bestexample is that kn own to En glish residen ts in Hon g

- Kon g as Dumbbell Islan d, which con sists Of two gran ite hills, each abo ut 300 feethigh an d 14miles lo n g , co n n ected by a low san dy isthmus 170 yardswide

,risin g 10 feet above n ormal high -water mark . The Po rtuguese

co lo n y Of Macao is,perhaps

,the mo st typ ical examp le Of a dumb

bell p en in sula .

There are several varieties o f dumb - bell islan ds,and their origin

is ascribed by Mr . Schofie ld to (1 ) decay Of ro cks, (2) partial sub

mergen ce o f the land, (3) rain storms, (4) destruction Of vegetation ,

(5) marin e actio n ,and these causes are examin ed an d exp lain ed in

detail . Nearly all the dumb - bell islands an d p en in sulas are com

p osed Of gran ite , gen erally partly decay ed,and their evo lution can

be fo llowed through all its stages in the examples n ear Hon g- Kon g .

The p ap er con cludes with a list of the islan ds an d p en in sulas of

this type n ear Hon g- Kon g , to the n umber Of forty - six .

CORRESPONDENCE.

THE SGURR OF EIGG .

_SIR,

— I have n o wish to en ter in to a con troversy up on the subj ectOf the Sgurr ofEigg with Dr . Harker, who se letter, I may be pardon edfor suggestin g , savours rather more of the Don than Of theSurvey man I may remark

,however

,that I have read

Dr . Harker’s pap er carefully ,an d did n ot fin d it convin cin g . The

o ccurren ce o f gran ite p ebbles in the con glomerate may n ot be n ewn ow ; I believe it was n ew when Mr . A . S. Reid and I made thediscovery— in have n ever seen an y o f th

eo lder gran ite

fragmen ts that Dr . Harker men tio n s, the gran ites ‘‘ that are n ot

exp o sed at the surface p o ssibly they may be o f Old Red San dston e age . The gran ite p ebbles we discovered In the co n glomerateare certain ly n ot Of Old Red San dston e age . In an y case

,this po in t

co n cern in g gran ite p ebbles Is arguable, but 1s n ot Vital .The questi on at issue between Dr . Harker an d my self Is somethin gmuch more imp ortan t, n amely ,

the relative values Of theo retical an dfield eviden ce . I bow to Dr . Harker’s kn owledge Of micro scop icp etro logy , but in matters o f field eviden ce each man must relyo n his own observatio n . It is p ossible to argue at an y len gth aboutp o ssibilities , probabilities , an d theoretical matters

,but there should

be n o po ssiblemistake about facts as Observed in the field . I cordiallyagree with Dr . Harker that a little kn owledge is dan gerous , but, onthe o ther han d

,assuran ce as to facts is very safe . An y o n e who has

a len gthy exp erien ce Of eco n omic geo logy— the kin d Of geo lo gicalwork that is practically useful , as distin guished from that which

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1 92 Corr esp on den ce— C. Carus Wi lson — J . W. Evan s .

THE CHINES AND CLIFFS OF BOURNEMOUTH.

SIR,—I believe that Mr . Bury is co rrect in assumin g that I am

resp on sible fo r the statemen t regardin g the gen eral in crease inthe steepn ess of the Bourn emouth cliffs . It‘ was made in a lecture11 The Bourn emouth Cliffs delivered at Bourn emouth in the

sprin g Of 19 12 . The matter was also discussed at the Geo lo gicalSociety after the readin g o f Mr . Bury

’

s pap er o n January 27, 1916 .

'

AS I have n ot Visited Bourn emouth sin ce 1912 I am un able torefer to the app earan ce Of the cliffs at the p resen t time , but in 19 12the alteratio n in the gen eral an gle o f face - slop e was unmistakable ,an d

,in fact, was n oticed by several local observers , an d sub

sequen tly co rrobo rated by the comparison o f numerous photographstaken between 1887

,when my systematic observatio n s began ,

and

1912 .

Sin ce the Undercliff .Drive was co n structed the re has been a

gen eral lowerin g of the beach westwards,an d hen ce a more rap id

removal o f cliff talus from the base through marin e erosio n an d

transp ort , hile, at the same time , there has been n o prop ortion atein crease in the rate of atmo spheric ero sion upo n the cliff - face .Hen ce the gen eral . an gle o f slope is n o lon ger approximately35 de grees, as was formerly the case . I predicted these chan geswhen givin g eviden ce at the Lo cal Governmen t Board In quiry heldat Bourn emouth in 1906, an d man y y ears before that in the lo calpap ers .

It has always seemed to me that an importan t factor In determin in gthe width an d depth Of a chin e l n the makin g 1s the bed of clay ,

o r ferrugin ous sandston e,so frequen tly presen t at vary in g dep ths

below the surface . A stream cuttin g its way through the softersan dro ck ceases to erode its bedwith the same rap idity when reachin g.a stratum o f clay or san dsto n e below

,while the widen in g Of the

chin e by atmospheric agen cies con tinues toprogress at the same rate .0 . CARUs -WILSON .

February 12 ,1920.

INCOME - TAX .

SIR,— A committee has been fo rmed to support the claim that

e xpen ses n ecessarily in curred by scien tific men should be allowedas a charge again st in come in arrivin g at their assessmen t for in cometax

’This is at presen t by n o mean s always the case where thei n come is a fixed salary from a Governmen t Departmen t or Publi cIn stitution . AS the who le questio n of the mode Of imp o sitio n is n owun der revision

,it is prop o sed to presen t a memorial to the Treasury

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. .A G. Church , D .S O .,M.C. ,

B .So . S,ecretary Of the Nation al Un io n

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JOHN W. EVANS

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GEOLOGICAL zMAGAZ’

INEVO LUME LVII.

NO. V.— MAY

,1920.

ED IT OR IA L NOTES .

THIS mon th our Edito rial n o tes are shorter than usual owin gto pressure o f o ther matter o n our space , esp ecially somewhat

len gthy correspo ndence which has to some exten t upset“the origin alpro gramme and caused o n e or two pap ers to be un avo idably heldover . Furthermore

,the in ciden ce of the Easter ho lidays has

made it difficult to keep up with curren t even ts in the geo logicalworld .

IN the lon g list o f recip ien ts o f various grades of the Order o f theBritish Emp ire we are glad to n o tice the names of some geo logists ,though few in number . They are as fo llows : Mrs . Shakesp ear,Dame BE . Dr . F . H. Hatch, O .B .E . Mr . J . Allen Howe

,O .B .E .

Miss G. L . Elles, M.B .E . Mr . H. T . Burls,M.B .E . We are by n o

mean s sure whether the first item on this list is correctly expressedif n ot, we offer apo logies .

AT the ann ua l meetin g o f the Prehistoric So ciety of East An glia,

held at the ro oms o f the Geo lo gical So ciety o n March 23, Professo rJ . E . Marr delivered his Presiden tial Address, which dealt main lywith the relation ship o f the dep o sits co n tain in g human relics tothe Glacial p eriod . He co n sidered that as the result o f Mr . ReidMo ir’s discoveries the existen ce o f Plio cen e man in Britain has beenproved . After n otin g the p o ssible existen ce o f glacial con dition sin this coun try in late Plio cen e times, he devo ted the main portion sof the address to the Pleist o cen e period . He regards the eviden ce asfavourin g the o ccurren ce o f a glaciation (the Cromer Drift glaciatio n )at the begin n in g of the Pleisto cen e p eriod,

fo llowed by gen ial condition s durin g Chellean - an d Acheulean times . After this fo llowedthe glaciatio n which caused the fo rmatio n o f the Chalky Boulderclay , which co in cided gen erally with Lower Mousterian times .

A slight rise of temp erature o ccurred durin g Upp er Mousterian ,

Aurign acian . an d S o lutrean times,though n o t n ecessarily sufficien t

to cause the ice to disapp ear from mo re n ortherly parts o f our Islan d,

and durin g the Magdalen ian p eriod the ice re - advan ced so uthwardto some exten t . If the p eriod from LowerMousterian to Magdalen ian

VOL . LVII .- NO . v. 13

1 94 Edi tor ia l Notes.

times be regarded as marked by on ly o n e glaciation i t would appearthat the Chelles—Acheul period immediately preceded the lastglaciation ,

a view in harmo n y with that o f the latest Con tin en talwriters . Pro fesso r Marr’3 views are largely based up on Mr . Mo ir’sdiscoveries in the Ip swich area

,but he brought co nfirmatory

eviden ce from o ther p laces . The latter part of the address dealtbriefly with chan ges Of sea - level durin g the times when man dwelt 1nBritain , and allusio n was made to certain river - diversio n s whichwere brought about in the same times . The Presiden t co n cluded byemphasizin g the vaguen ess of some o f our in terpretation s , and

urgen tly advo cated the co llectio n o f more facts . a task which themembers of the Society had already largely un dertaken durin g thefew

_y ears o f the So ciety ’

s existen ce .

AT the meetin g o f the Geo logical Society of Lon don o n March 24the Presiden t an n oun ced that the Coun cil had awarded theProceeds o f the Dan iel Pidgeon Fun d available in the presen t yearto Miss Marjorie Elizabeth Jan e Chan dler, who propo ses to ih

vestigate the Oligocen e Flora Of the Hordle Cliffs (Hampshire) ,and to Lauren ce Dudley Stamp , B .Sc .

,F.G.S

who prop oses to make a comparative study o f the Down to n ian an d

Gedin n ian in No rth -Western Europ e .

WE have rece ived the fo l lowin g letter from a valued corresp on den t,too late fo r in sertion in the

,

ordin ary p lace in the Magazin e , so weven ture to put it in our Editorial No tes in stead :SIR,

— I bel ieve the fo llowin g coup let was written about the timeo f the publication o f Bucklan d’

s Bridgewater Treatise on Geo logy .

Could an y of y our readers g ive me the autho r’s n ame ‘2

Al l , al l , was dark an d drear befo re the F lood ,

T il l Bucklan d came , an d made i t clear as mud "

XY Z .

Addendum to Obituary Notice of R. Etheridge , jun . (p .

MR . R . BULLEN NEWTON, of the British Museum (Natural

History ) , Lon do n , SW. 7,writes : An excellen t n o tice o f

R . Etheridge , jun .,app ears in the Sydn ey Dai ly Te legrap h, written “

by Professor Edgeworth David,F.R .S. SO far as I can trace ,

R . E ., jun .

,was a member o f the Royal Society o f New South

Wales,an Hon orary Fellow o f the Royal Society o f South Australia,

and a Corresp ondin g Member of the Royal So ciety o f Victoria .

In past y ears he had been a Fellow o f the Geo logical So ciety o f

Lon don ,an d had also been Presiden t o f the Royal Physical Society

o f Edin burgh . At the time Of his death he was a member o f theMalaco logical Society of Lo n don .

”

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196 Char les Lapworth.

wo rk was based and the un ravellin g o f the comp lex Of those up landswas logically fo llowed by that o f the much greater complex o f theNorth Western Highlands .

At the outset he found that field work i n the Southern Uplandsrequired to be supp lemen ted by study o f the fo ssil eviden ce

,and

accordin gly devo ted himself so assiduously to the study o f thegrapto lites that he rapidly became the leadin g autho rity upon thisgroup o f o rgan isms

,and remain ed so to the day o f his death . In

acquirin g his kn owledge of the se an imals,he mastered the bio logical

memo irs treatin g o f their n earest livmg allies, an d thus in ciden tallytrain ed himself as a first- rate paleeo n to logist . How accomp lishedhe was as such was later shown by his in gen ious restoratio n of thestructure Of the trilobite, Olen ellus (Calld oca) Oallavet

'

, from study o f

the imp erfect fragmen ts which he discovered in the Cambrianrocks of Comley .

Again ,when so lvin g the riddle o f the North -West Highlands,

various p etrographical question s con fron ted him,and his study o f

p etro logy en abled him here to co n tribute much to our kn owledge ofthe pro cesses o f metamo rphThe severe illn ess develop ed as the con sequen ce o f his work in the

Highlan ds had a p erman en t effect up on Lapworth , an d brought toa close the strenuous days o f his fie ld- Work . Although hesubsequen tly accomp lished much amo n g the o ld ro cks o f the classicregio n o f Siluria and elsewhere

,the work was n o t marked by the

in ten se vigour which characterized the prosecution Of his earlierlabours . When we recogn ize that in his earlier y ears he washamp ered by wan t o f leisure, an d in his later by lack Of health, weare amazed at what he actually p erfo rmed .

But though his fie ld - work was imp eded in later y ears , the activityo f that mo st o rigin al min d was un impaired . Lapworth

’

s earlytrain in g in geometry alway s sto od him in go od stead

,an d en abled

him readily to visualize in thre e'

dimen sio n s . HisWork in theUp lan dsand Highlan ds o f Sco tland aroused his i n terest in tecton ic problems

,

and led to the elaboratio n o f his fo ld theo ry . He treat-cd of thisat much length in his Presiden tialAddress to the Geo logical Sectiono f the British Asso ciatio n at Edin burgh in 1892 , an d fin ally turn edto it on ce again in that part of his Presiden tial Address to theGeo logical Society which deals with geo logy an d physics . Man y o f

the sen ten ces in this are pregn an t with mean in g an d give us a

glimpse o f the workin gs o f the min d o f a seer . How o n e regrets thathe had n either time n or Opportun ity to .write a great work up on

theoretical geo logy embody in g his rip er co n clusion sThose who wish to gain a just idea o f Lapworth

’

s wo rk shouldread n ot o n ly the accoun t given in this Mag azi n e i n 1901 but alsohis own address to the Geo lo gical So ciety . Parts o f that addressmay be regarded as autobio graphical , for when he writes o f the variedduties o f a geo lo gist he is o ften un con sciously describin g his own

methods of work in research,scien tific practice

,and education .

Char les Lap wor th.

We claim Lapworth as on e of the foremost geo logists o f all time .His output Of published work must be estimated by quality ratherthan quan tity,for there is n o doubt that his ill - health o f late r y earspreven ted him from publishin g as fully as would o therwise have beenthe case .The pro foun d influen ce exerted by what is published is gen erally

re alized,an d we n eed dwell n o lo n ger up on this part of his work .

But much o f his kn owledge which he did n o t commit to prin t isn ot lost

,but is bearin g fruit, and will co n tinue to do so . For

Lapwo rth was a great teacher, an d his studen ts have proved thisin man y ways . His influen ce however was n ot by an y mean scon fin ed to the lecture— ,

ro om and dui in g tlie y ears o f his Professoriateat Birmingham the city was a geo logical Mecca,

where geologistso f all classes wen t to discuss their wo rk with o n e who was alway sready to help ,

and they ever came away en riched with n ew ideas,which will aid materially in swellin g the sto ck o f geo logical kn owledge .

Man y o f us w ill recall the even in gs when ,after a hard day s

work in the examin ation - ro om o r elsewhere,an d havin g partaken o f

a cheerful din n er, Lapworth wo uld p erhaps sit downC

at the pian oand p lay his accompan imen t to some gay son g from the latestpopular op era,

an d the listen er would thin k that the day ’

s work wasover

,un til a move was made to the study an d the Pro fesso r p oured

out treasures from the storehouse of his min d un til the small hourso f the mo rn in g , and the brain o f the awed listen er reeled . Or, afterthe co n sump tio n o f the midday sandwiches o n some moun tain s lop e ,he would exp lain the structure o f the surroun din g coun try durin gthe frequen t in tervals between the relightin g Of his p ip e , un til itsasp ects durin g the ' differen t geo lo gical periods seemed to glowbefore the hearer’s vision .

Exp erts and tyro s alike have had these exp erien ces, sittin g at thefeet of the master . This was

,indeed, a liberal education ,

an d on e

which will“ preven t his un published ideas from bein g for ever lost .How sad it is to realize that the exp erien ces are n ow thin gs o f thepast " But the memories of them are dear, and we treasure thereco llection Of the waves o f joy an d earn estn ess altern atin g o n his

an imated face,like the chan ges o f

,

light and shade on a hillsideben eath a dapp led sky .

Would that we could presen t a faithful p icture o f him to tho sewho had n ot the privilege o f kn owin g .him , but the task i s impo ssible .We have lo st a great geo lo gist, and

:D

withal a man of very beautifulcharacter .

ORIGINAL ARTICLES.

In tra - Jurassic Mo veme n ts an d the Un de rgroun d Structure

o f the So uthe rn M idlan ds.

By Pro fessor ARTHUR HUBERT Co x,M.Sc .

,Ph .D. ,

and

ARTHUR E. TRUEMAN,D .Sc .

,F.G.S ,

Un iversity Co llege o f SouthWales and Monmouthshire

, Cardiff .

I . INTRODUCTION .

RECENT in vestigation s in to the relation ship between geo logicalstructure an d magn etic disturban ce have called atten tion to

the existence o f a lin e of an ticlin al fo ldin g that affects the Triassicand Lower Jurassic ro cks in the n eighbourho od OfMelton Mowbray ,Le icestershire .

l It has further been shown to be highly probablethat this p ost - Triassic an ticlin e fo llows an d is

“

foun ded up on thelin e o f an Older an d more pron oun ced an ticlin al up lift of pro - Permiandate . 2 The presen ce of the p o st - Triassic an ticlin e is indicated on

the geo logical map by the sudden swin g round of the outcrops of

Triassic an d Liassic ro cks from the n ormal n orth to south (or“

N.N.E . to S.SW. ) directio n in to a n o rth west to south east direction ,

an d then back again to the n o rmal (N.N.E . to S.S.W. The suddenchan ge of strike i s n oticeable i n the outcrops of all the formation sfrom the Keup erMarl to the In ferior Oo lite in clusive

,but it becomes

least apparen t an d is gradually lost in the succeedin g division s of

the Middle Jurassic . This suggests that the movemen ts that gaverise to the an ticlin al structure had died down durin g or prior to thedeposition of the Bathon ian ro cks .

A simi lar swin g is‘

seen in the Vale o f Mo reton ,an d again in the

n orth Cotteswo lds, an d these were shown by Mr . S. S. Buckman

to be due to an ticlin al an d syn clin al fo ldin g ;3 the same writer hasrep eatedly shown by his detailed zo n al studies that the In feriorOo lite an d o ther divisio n s o f the Jurassic ro cks frequen tly showeviden ce of an ticlin al fiexurin g an d p en eco n temp oran eous ero sion i‘“Fo r in stan ce, he showed that the sequen ce of the Upp er Liassiczo n es is comp lete , or n early so

,at Bredon Hill , which is situated o n

a syn clin al axis, While elsewhere n on - sequen ces frequen tly o ccur,

especially alon g lin es o f an ticlin al fo ldin g . He has further suggestedthat movemen t has o ccurred alo n g man y o f these lin es at in tervalsdurin g Meso zo ic an d even Tertiary times .

5

1 Co x , A Rep o rt on Magn e tic Disturban ce s in Northamp ton shire and

Le icestershire an d the ir Re lation s to the Ge o log ical Structure Phil . Tran sse r. A, vo l 219 ,

19 19 ,App e n dix, pp . 73—135 .

2 Loc. cit. , p . 122 .

3 Buckmah ,

“The Toarcian of Bredon Hil l Quart. Journ . Ge o l . Soc

vo l . l ix , 1903, p . 449 .

4 A list o f Mr . Buckman’s chie f p ap ers on these subj e cts is given in Quart.Journ . Ge o l . So c vo l . lxvi , 19 10 , p . 53.

5 Op . sup ra cit.,1903, p . 449 .

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200 A . H. Cox an d A . EJT'

ru eman

ben din g o f outcrops without the aid of an y an ticlin al flexurin g . On

the - otherh and, the existen ce o f the valleys may b e sign ifican t .whenaccoun t is taken Of the kn own preferen ce o f river valleys for an ticlina l areas

, as in stan ced by the an ticlin es already proved through .

Melto n Mowbray an d the Vale o f Moreto n .

Although the outcrop s Of the various members o f the LowerJurassic, particularly the Lower an d Middle Lias , suffer markeddeviation s in the valleys men tion ed above

,

'

it is n o ticeable that theoutcrops Of the Middle an d Upp er Jurassic rocks are n o t affectedi n an y way . This at o n ce suggests that the flexurin g tock p lacedurin g Jurassic time, an d that the movemen ts had died downprior to the dep ositio n of the Corn brash and Oxfo rd Clay .

If such in tra—Jurassic fo ldin g has o ccurred it would give riseto n on—sequen ces alon g the an ticlin al axes

,while in the com

p leme n tary syn clin es the - successi on should be more n early comp lete .This has proved to be the case wherever the strata have beensufficien tly studied

,as in the Vale o f Moreton an ticlin e an d the

Bredon syn clin e, in vestigated by Buckman .

III . FURTHER EVIDENOES o r INTRA - JURASSIC MOVEMENT .

In attemp tin g to use zon al methods to demon strate the existen ceo f Jurassic fo ldin g in the area between the Vale Of Moreton an d

Melton Mowbray , we are un fortun ately met by a great lack Of

detailed in formation which can be regarded as trustworthy in the

light o f recen t refin emen ts o f zon al work . Further,it has frequen tly

happ en ed that the thickn ess o f a subdivisio n o r‘ zon e as determin ed

at on e locality has been quo ted as the thickn ess throughout a who le

coun ty . In poin t o f fact, thickn esses may vary greatly within thecoun ty limits . For these reason s we have been un able to use man yo f the figures that at first sight would app ear to be available . Owin gto this lack Of reliable in formation o n ly certain well marked zo n escan at p resen t be used for our purp oseIt is obvious that n o n - sequen ces and lo cal variatio n s in thickn esswill show best in thin zon es . Further, the mo st useful dep ositswill be tho se which Were laid dowh after p eriods o f con

siderable movemen t,thus Mr . Buckman has foun d that some of

the mo st n o table Iion sequen ces corresp on d with the Baj ocianup lift an d denudation . Durin g the dep o sition Of the Lias themaximum movemen t o ccurred between the times o f accumulation o f

the Middle an d Upp er Lias, that is after the hemera o f sp in ,ali when

slight up lift to ok p lace , an d gen tle fo ldin g resulted l n the formationof several shallow basin s in which first a thin dep osit of theTran sition Bed (acutum zon e) an d then the lower zo n es Of the Upp erLias were laid down .

2 These beds would n aturally be absen t or very1 Buckman , The Clceve Hil l Plate au Quart . Journ . Ge o l . So c. , vo l . l viii,

1897, p l . xlvi ; and also“The Baj ocian o f the North Cotteswo lds ibid .

,

vo l . lvii , 190 1 , p . 146 .

2 Trueman, The Lias Of South Lin co ln shire GEOL. 19 18 , p . 108 .

In fra - JurassicAl oo emen ts . 20 1

attenuated n ear the an ticlin al axes,an d would be best develop ed

in the syn clin al areas .

The variation s in the thickn esses Of these zones Will n ow be co nsidered in o rder to se e whether there exists an y defin ite relatio n shipbetween such variatio n s an d the p ositio n s o f the p ostulate fo lds .

(1 ) Acutum Zo n e .

—The acutum zon e i s esp ecially suitable fo r thepresen t purp ose for several reason s; As the .

“ Tran sitio n Bed

between the Middle and Upp er Lias , an d con tain in g man y fo ssils,it has received much atten tion . It has also been well expo sed inmany

'

workin gs for Marlsto n e Iron ston e,while it is very thin an d

its fossils easily recogn ized,so that there are few records that can n o t

be utilized .

The distributio n of the dep osits o f acute’

age con stitutes a strikin gcon firmatio n o f the suggested fo ldin g .

1 While the acutum zo n e iswell represen ted aroun d Linco ln

,it is probably absen t at Gran tham,

appearin g again as a thin layer at White Lodge n ear VValtham - o n

the -Wo lds,Leicestershire

,in the Old Dalby syn clin e . In the n eigh

bourho od o f the Melton Mowbray an ticlin e the acutum zo n e has n otbeen recorded

,a fact

'

which makes it extremely probable that thezon e is n ot represen ted there . South of this. region ,

however,in the

Tilton syn clin e, the zo n e attain s its best developmen t around Tilton .

It has again n ot been reco rded an ywhere in the n eighbourho od o f

the p ostulated Market Harborough an ticlin e,an d it is likewise

thin or absen t alon g the lin e o f the supp o sed Weedo n an ticlin e“,but its presen ce has been proved in the in terven i n g district , whichin cludes what we propose for co nven ien ce to refer to as the Co ldAshby syn clin e .Again ,

between No rthamp to n an d Ban bury the acutum zo n e iswell seen

,an d has been described by . man y Observers at Chipp in g

Warden an d Byfie ld . Towards the suggested an ticlin e throughBan bury ,

however,the dep o sits again thin out

,an d at Kin g’s

Sutto n a very atten uated represen tative rests o n an eroded surfaceofMarlsto n e . West o f this lin e the acutuin zo n e on ce more thicken sin the regio n of the Edgehill syn clin e , but still further south o r westit has n ot been

'

foun d .

At several localities,such as Asto n lo Wall an d Milto n ,

situatedn ear the lin es Of the p o stulated an ticlin es

,the dep o sits con tain

ro ll ed materials o r p ebbles , a further eviden ce of slight erosion .

(2) The Tenuicostatum Zon e — The ten uicostatum zon e (formerlymiscalled the an nulatum zo n e) o ccurs at the base o f the UpperLias immediately above the Tran sitio n Bed (acutum zon e) . In man y

1 The thickn esse s of zon e s have be en Obtain ed main ly from the fo l lowin gSource s : Judd,

The Geo logy of Rul lan d,

etc. (Mem . Ge o l . 1875 .

Walfo rd, Pro c . Warwick . Nat . Fie ld Club,1878 , p . 37 . Thomp son , Journ al

Northan ts ' Nat. Hist . So c ., vo l . ii , 1882—3. Wilso n 85

“Crick , GEOL . MAG . ,

1889 , p . 296 . Thomp so n an d o the rs in Rep o rt of Brit . Asso c. ,189 1 , p p . 334—5 1 .

Wo odward, Lias of En gland an d Wa les (Mem . Ge o l . 1893.

Richardso n ,Han dbook to the Geo logy of Cll e ltenham,

etc.,1904 . True -

1:12am,GEOL . MAG .

,19 18, pp . 106—8 .

202 A . H. 0 0 50 an d A . E . Trueman

records n o attemp t has been made by authors to iden tify theDactyliocerates o f this zon e, but as the dep o sits are frequen tlypap er shales

,an d con stitute the lower part of the “ Fish Beds

or Dumbleton Beds o f Professor Judd,

1 it can g en erally be iden tifiedfrom descrip tion s o f the section s .

2

It has beer-1 shown by Mr . Buckman an d others that theten ulcostatam zon e attain s its maximum thickn ess in Yorkshire ,is thick in L1n co ln shire

,.and then ce southwards is reco gn izable as

a very thin lay er .

8 But this gen eralization“

is upset by a suddenthicken in g o f these beds alon g the Bredon syn clin e , for at Dumbletonthey are extremely well develop ed, a fact which further suggeststhe existen ce o f a basin there in Liassic times .

As the tenuieoslatmn zon e is traced southwards from - Lin co ln shire ,in tho se districts where a sufficien t number of thickn esses 1s avai lable ,further indicatio n s are obtain ed of in tra- Liassic movemen t ; thisagain app ears to have o ccurred alon g the axes that have beenp reviously n o ticed . There 1s

,for in stan ce

,a slight thicken in g 1n the

Old Dalby syn clin e , although the zon e geii erally 1s rapidly . thin n in gout southwards . The probable absen ce of the zon e i n the districtaroundWeedon n ear theWeedon an ticlin e is in terestin g , as the zon eis certain ly presen t at Chipp in g Warden an d further to the southwest . The zon e on ce more thins towards Ban bury ,

and Mr . J .

Prin gle in forms us that he believes it to be absen t just n o rth - westo f Ban bury ,

where the overly in g eaaratuqn zon e,itself attenuated,

rests with a n o n—sequen ce o n an in con stan t represen tative o f theacatam zon e which fills small ho llows in the un derly in g Marlston e .There was

,therefore

,but little dep o sition over this region durin g a

p eriod in which dep osits belon gin g to several zon es were accumulatin gelsewhere . Still further south - west

, pap er- shales o ccur at Chipp in gNorton in the Edgehill syn clin e , but thin out o n ce more towardsthe lin e o f the Moreton an ticlin e

,on ly to thicken in the Bredo n

syn clin e , as we have already indicated .

The results obtain ed from our study o f the aeatam an d ten n i

costatum zon es are summarized in the table o n p . 203, in which itis seen that the variatio n s in these two zo n es take place at exactlytho se lo calities where they would be exp ected if the fo ldin g which isindicated by the course o f the outcrop s was in progress durin g thep eriods o f dep osition . In each case the dep osits thicken towardsthe syn clin es and thin away towards the an ticlin e .(3) Other Zon al Eviden ce — WVhile it is n o t y et p o ssible to fo llow

o ther zon es in similar detail acro ss the . who le of the Midlan ds , thereare certain zon es traceable for short distan ces which afford furthereviden ce o f some of the supp o sed in tra - Liassic movemen ts .

1 Judd , The Geo logy of Rutland, etc. (Mem . Ge o l . 1875 , p . 83, e tc.

2 Although in some of our figure s . p erhap s a p o rtion o f the exaratum zon emay also be in cluded .

3 Buckman , Ce rtain Jurassic (Lias - Oo lite ) Strata o f South Dorset, etc.

Quart. Journ . Geol . Soc .

,vo l . lxvi , 1910 , p . 88.

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204 A . H. 0 0 93 an d A . E . Trueman

from Yo rkshire as a co n sequen ce of some region al movemen t theresults of the regio n al movemen t almost comp letely co n ceal theresults of, an y min o r fiexurin g durin g that time . Atten tion has inthe past n aturally been drawn to the larger lateral variation s , withthe result that an y min or o r lo cal variatio n s superp o sed on theregion al o n es have been overlo oked .

As remarked above,we have failed to accumulate sufficien t

eviden ce to prove the o ccurren ce o f such lo cal variation s in thefo rmation s con sidered as

'

a who le . But so far as the reco rds go ,

they tend to co nfirm the results obtain ed by a critical examin ationo f subdivided zon es

,such as the acutum an d ten aicostatum zon es

detailed above . Fo r examp le , the co llected figures suffice to showthat the Upp er Lias thicken s in the Old Dalby syn clin e an d in theBredon syn clin e . As regards the Lower Lias, there are eviden ceso f local thicken in g in the syn clin al areas o f Bredon an d Badby .

As regards the Rhaetic there is again a thicken in g in the Bredon.syn clin e , an d p erhap s also in the Old Dalby syn clin e . It seems

probable, therefore, that when sufficien t data are available co n cern in gthickn esses o f o ther zo n es an d subdivisio n s

,it will be po ssible to

trace the effects o f the lo cal movemen ts in mo st of the division sbetween the Rhaetic an d the In ferior Oo lite In this way it may

prove p o ssible to separate the effects o f lo cal up lifts from those dueto regio n al movemen ts in vo lvin g widespread tiltin g with co n sequen ttran sgression or regression .

(5 ) Eviden ce of Mooemen ts f7o in p ost Bathon ian Rocks .

— We haveshown above that an examin ation of certain thin zon al depo sitsapp ears to co nfirm the eviden ce o f outcrop that fo ldin g was inprogress at in tervals in Liassic time . Variations in thickn esses o f

the maj o r divisio n s y ield some addition al supp o rt . Taken in co n

jun ction with the results already men tio n ed as obtain ed byMr . Richardso n

,that lo cal movemen ts were takin g p lace in Rhaetic

times alon g the same lin es that were afterwards fo llowed by Baj ocianmovemen ts, we fin d that there was gen tler but almost co n tinuousmovemen t alon g defin ite lin es up to about the en d of Baj ocian time .Then these particular movemen ts app ear to have ceased,

for theoutcrop s of the Bathon ian and higher formatio n s are but littleaffected .

Nevertheless,it is still p ossible to trace the southward pro lon gatio n

o f the fo lds beyon d the area o ccup ied by Baj o cian ro cks, becausemovemen t alon g the same lin es seems to have been ren ewed at certainlater p eriods , so that alon g the an ticlin al lin es den udatio n Wasrep eatedly at a maximum . Thus it is mo re than a co in ciden ce thatalon g the southward pro lo n gatio n of the Moreton an ticlin al axisthe Lower Cretaceous San ds should at Farin gdon sudden ly cometo rest directly on the Corallian ,

while still further south , just wherethe pro lon gatio n o f the same lin e cro sses the Vale o f Pewsey _

up lift ,the Tertiary beds overstep n early the who le o f the Chalk an d“

comein to their closest proximity to the Upper Green san d.

Tiara - Jurassi cMovemen ts . 205

Similarly at Wallin gford on the southward pro lon gation of theBan bury ax is

,the course of the Upp er Green sand outcrop clearly

indicates the existen ce of gen tle an ticlin al fo ldin g .

In the region further east , Mr . R . H. Bastall has called“

atten tionto the an ticlin al disp o sition of the Upp er Jurassic with regard toan axis o f maximum ero sio n which passes n o rth - westwards throughSandy (10 miles east of Bedford) , an d he has exp lain ed the structuresas due to a pre

- Cretaceous p osthumous uplift o f the Charn ian axis .

1

IV. RELATION o r THE FoLDs TO PALZEOZOIC OUTCROPS .

It is on ly to be exp ected that several o f these axes o f Meso zo icuplift should be align ed with up lifts that have resulted in exp osin gthe n earest outcrop s .o f Palaeo zo ic ro cks . Thus - the Mo reton an d

Win chcombe an ticlin es are align ed resp ectively with the Warwickshire an d South Staffordshire Co alfields , an d the Chipp in g Campdenand Bredon syn clin es with the troughs between the Warwickshireand South Staffordshire and South Staffordshire an d Forest o fWyreCoalfields

,while the co n n exion between the Melton Mowbray

an ticlin e an d the uplift o f pre - Cambrian ro cks in Charnwo od Foresthas been discussed elsewhere . 2 The con n exion s between theremain in g an ticlin es , the Ban bury ,Weedo n ,

an dMarketHarboroughfo lds an d the n earest Palaeo zo ic ro cks are n ot so clear

,but it will

be shown that there are reason s fo r con n ectin g bo th the Ban buryand the Weedon fo lds with the Warwickshire Co alfield,

an d theMarket Harborough fo ld with the Charnwo od Forest area .

Several of these areas o f Jurassic fo ldin g have already beenexplain ed as due to p osthumous movemen ts alon g axes o f Palaeo zo icup lift . This was suggested as early as 1901 by Mr . Buckman

,in

discussin g the Baj o cian ro cks o f the North Co tteswo lds

Mr . Buckman showed that pen econ temporan eous ero sion is likelyto have taken p lace alon g similar lin es at differen t times , and therefore may be con n ected with the fo lds in the Palaeo zo ic rocks, an dmay

' have a bearin g o n the thickness. o f the ro cks overly in g thecoal measures Pro fessor W. S. Boulto n has more recen tlysuggested that min ute Jurassic zon al studies will all have theirvalue when estimatin g the n ature and thickn ess o f cover over theburied coal measures .

5A similar suggestion was made by Pro fessor

P. F . Ken dall regardin g an ticlin al axes in East An glia,

6by

Mr . Bastall 7 for the pre—Cretaceous up li ft which caused excessivedenudation o f Upp er Jurassic rocks alo n g a con tin uatio n o f the

1- Rastal l , Cambr idgeshir e : Ge o logy in the Fie ld, p t . 1, 19 10 , p . 143.

Co x , Phil . Tran s , se r. A , vo l . 2 19 , App en dix , 19 19 .

3 Buckman ,

“The Baj o cian of the No rth Cotte sWo lds Quart . Journ .

Ge o l . Soc . , vo l . lvii , 1901 , pp . 147—9 .

Op . cit . , p . 154 .

5 Preside n tial Addre ss to Se ction C (Ge o logy ), Re p ort Brit. Assoc Newcastle - on - Tyn e , 19 16, p . 383.

6 Rep ort of the Roy al Commission on Coal Supp lies, p t . ix ,App en dix iii .

Cambridge s'hflr e : Ge o logy in the Fie ld , p t . 1

, 19 10, p . 143.

Charn ian axis, and again by on e of us in the recen tly recogn izedMelton Mowbray up lift . 1It will be n o ticed that the axial lin es of the flexures chan ge in

direction from east - west at Melton Mowbray to n orth - west— southeast at Market Harborough,

then to approximately n orth - n orthwest— south - south - east at '

Daven try an d at Ban bury ,and fin ally

to a n orth - south directio n in the two cases o f the Vale of Moretonand the Win chcombe structures . The variation in the direction o f

the differen t axes may be ascribed to sp littin g an d fin gerin g- out

southwards of the main axis o f p o st - Triassic up lift, the Pen n in eaxis .

“ The fin germg—out o f the p o st - Carbon iferous pre- P'ermian

Pen n in e uplift has been described by Profess o r Ken dall 2 an d byPro fessor Fearn sides,3 an d it was ascribed by the latter writer toa laggin g of the eastward- movin g fo lds as they approach theburied area o f o lder ro cks which we kn ow to un derlie East An glia .

If,as the structures indicate , the Triassic an d Jurassic movemen ts

fo llowed the lin es o f the earlier pre - Permian movemen t,the radial

arran gemen t o f the fo ld - axes is re adily exp lain ed . The existen ceo f such a radial arran gemen t serves to accoun t for the in creasedn umber o f an ticlin al areas in the south an d east as compared wi ththe cen tral Midlan ds . If it were p o ssible to differen tiate an d map

particular horizo n s in the thick Keup er Series , as has been aecomp lished by Dr . Matley 4

over p art o fWarwickshire,it would probably

prove easy to trace all the fo lds from the Jurassic ro cks across thein terven in g K eup er to the Palaeo zo ic areas

,and so to se e the south

ward sp littin g o f certain o f the fo ld - axes .

Further, it should be n o ted that,while the No ttin ghamshire ,

Warwickshire , an d South Staffordshire Co alfields all have a n o rthsouth alignmen t, due to p ost - Triassicmovemen ts which have affectedthe Meso zo ic cover

,the Palaeo zo ic ro cks in each coalfield show

the presen ce of o ther axes due to o lder n orth—westerly movementsoblique to the presen t alignmen t . For examp le , the WarwickshireCo alfield has two marked Charn ian an ticlin al axes , each o f whichbrin gs up Cambrian rocks . On e o f these axes is on the presen tn orth - eastern margin o f the coalfie ld at Nun eaton an d the o thero n the west ern margin at Do sthill

,

5so that the structure within

the coalfie ld is comp lex , due to two systems o f up lifts which ‘

cro ss

o n e an o ther obliquely ,o n e pre

- Triassic an d o n e p o st—Triassic . Now

in each case it is probable that while the n o rth - south p o st—Triassicmovemen ts were in p ro gress, there was simultan eous p o sthumous

1 Co x ,Phil . Tran s , se r. A , vo l . 219 , Ap p en dix , 19 19 , p . 124 .

2 Rep ort of the Roy al Commission o n,Co al Supp lies , p t . i x , App e n dix iii ,

1905 .

3 Some Effe cts of Earth - movemen t on the Co al Measure s of the She ffie ldDistrict,

”Part II Tran s . In st . Min . En g ,

vo l . 11, p t . iii , 19 16 , p . 107 (withrefere n ce s ) .

4 Matley , The Up p e r Keup er (or Arden ) San dston e Group an d Associated

Ro cks of Warwickshire Quart . Journ . Ge o l . So c ., vo l . lxviii , 19 12 , p . 269 .

5 Geo logy of the Coun try aroun d Lichfie ld (Mem . Ge o l . 19 19 , p . 7.

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Various further co in ciden ces in symmetry app ear, suchdisp ositio n of the pre—Cambrian an d Cambrian rocks o f Leicestershire

,

with their south easterly strike as. compared to the pre Cambrianand Cambrian ro cks o f Shropshire , with their south - westerly s trike .Yet o ther resemblan ces become app aren t from a study o f the map ,

an d it seems likely that a fuller kn owledge o f the distribution o f

the con cealed Palaeo zo ic ro cks would y ield y et other similarities .

VI . SUMMARY .

1 . The o ccurrenc e o f an ticlin al fo ldin g durin g. Jurassic times

has been demon strated by Mr . Buckman’

s detailed zon al work In

the Vale of Moreton an d in the North Co tteswo lds . These an ticlin es are indicated o n the map by marked ben ds in the outcropsof the Lower Jurassic formatio n s .

2 Similar bendin gs o f outcro ps are seen at several lo calities111 the Eastern and

t

So ii thern Midlan ds , an d the structure at o n e

such lo cality— Melton Mowbray— has recen tly proved to be an ticlin al .3. In tra—Jurassic fo ldin g betrays itself by n on—sequen ces an d

reduced thickn esses o f Lower Jurassic zon es alo n g an ticlin al axes .

Such eviden ce suggests the existen ce o f an ticlin al structures in then eighbourho od o f Ban bury , Weedon ,

an d p erhaps also MarketHarborough , i n addition to the cases men tio n ed above .

‘

4 . Movemen t was p robably almo st con tinuous alon g some o r allo f these axes

,at least from Rhaetic to Baj o cian times . Outcrop s

of p o st - Batho n ian “

formatio n s are n ot affected by the flexures ,although the fo ldin g was p erhap s ren ewed in later Jurassic o r evenTertiary times .

5 . Several o f these lin es_

o f Jurassic fo ldin g probably fo llow thelin es o f earlier an d more p owerful movemen ts . The bearin g o f

such fiex ure s o n the structure o f the Palaeo zo ic flo or is discussed .

' 6 . Atten tion is called to a curious symmetry in the disp o sitionof the Palaeo zo ic formation s o n either side o f a pro lo n g

'

atio n'

of thePen n in e ax is .

No te o n a New Vo le an d o the r Remain s from the

Ghar Dalam Cave rn . Malta .

By DOROTHEA M. A . BATE ,Hon . F.Z .S.

N 1916 the writer published a l ist o f the vertebrates of whichremain s had been obtain ed from the Pleisto cen e cave an d

fissure dep o sits o f Malta . Early this y ear (19 19 ) a few ratherfragmen tary remain s were forwarded by Mr . G. Desp ott to theBritish Museum (Nat . Hist . ) fo r iden tificatio n . These are from theGharDa-l

'

am Cavern ,from which a n umber of sp ecimen s have already

been o btain ed .

2 As some o f the sp ecimen s lately received add to

1 Pro c . Zo o l . p . 421 .

Proc . Ro y . Soc . ,

“

vo l . l iv,1 894 , p . 2 74 .

our khowledge o f the faun a in question It may be worth while torecord the fo llowin g n ot-es .

MAMMALIAo.

Mammalia are repre sen ted by fragmen tary remain s o f Cervus

elaphus, var . barbaras,o f two species of roden ts an d o f a small

fox . In cluded amon g the roden t remain s is a right femur o f an

immature an imal,and this app ears to agree most clo sely with that

o f Rattas which has n o t been recorded previously from the cavedeposits but two sp ecies o fwhich R. decuqn an us andR. alexandm

’

nus,

are recorded in Dr . Gulia’

s list o f the recen t mammals o f theMaltese Islands .

’

An o ther sp ecies is represen ted by a left an d right mandibularramus, the fo rmer con tain in g the in cisor o n ly ,

while the latter stillretain s the two an terio r cheek teeth as well as the in cisor . Thereare also two right femora an d a tibia

,which seem to belo n g to the

same sp ecies . The man dibular rami have been compared with thoseof several species bo th recen t an d extin ct

,and so far as can be

judged from such scan ty material they app ear to represen t an un

described sp ecies mo st n early allied to Arvico la (Tyrrhen r‘

eo la )hen se lz

'

Maj or . from the Pleisto cen e o ssiferous breccias o f Sardin ia .

2

It is prop osed that the Maltese sp ecies be kn own as

ARVICOLA MELITENSIS,sp .u .

The characters o f the lower jaw an d teeth show it to be clo selyallied to A . T . ) hen sel

fl,from which it may be readily distin guished

by its co n siderably smaller size . Owin g to the imp erfect state o fthe specimen s it is difficult to give comparative measuremen tso ther than the an tero -

po sterior len gth o f the first two cheek teeth ,which in A . hen se lt

'

is 55 mm . an d in A . me liten sis 45 mm .

Although p ossibly n ot a con stan t character, it may be worthmen tion in g that in Dr . Fo rsyth Maj or’s figure 3 o f the crown -

patternof the lower den titio n of A . hen se lt

’ the who le o f the den tin e areao f the an terior lo op is con fluen t whereas this lo op in A . me liten sis

is practically divided in to two parts (se e Text - figure ) .As in A . hen se lt

’ the lower cheek teeth in A . melfl ten sis are ratherwide crown ed

,an d the en amel is somewhat thin n er than in the

recen t Pitymys . Dr . Forsy th Maj or’s subgen us, Tyrrhen ico la,was based chiefly o n cran ial characters , and it will be in terestin g tose e if further material from Malta bears out the . clo se relatio n shipindicated by the lower jaw .

Other mammalian remain s con sist of the an terIOr half o f a leftlower carn assial

,a left lower can in e

,an d a n umber o f imp erfect

limb bon es o f a small sp ecies of Vulp es . These,as also some

sp ecimen s belon gin g to the Man chester Museum kindly len t byMr . J . Wilfrid Jackson

,

‘

have been carefully compared with man y

1 Nin th In tern ation al Zo o l . Con gre ss , Mon aco . 19 13, pp . 545—55 .

2GEOL . MAG . , 1905 , p . 504 .

3Lo c . cit . , p . 505 .

VOL . LVII .— NO . V .

210 M'lss D. Bate— A New Vo lefr om Ma lta .

recen t and fo ssil sp ecies in the British Museum . They seem to shown o characters sufficien tl y co n stan t or distin ctive to warran t theirseparation as a distin ct sp ecies , but eviden tly represen t a smallrace with a weak den tition an d slender limbs , smaller thanV.

'

fichn usce from Sardin ia,an d probably approximatin g in size

to V. n i lotica . of which n o skeleton has been available for com

p arison . The extreme slendern ess of the proximal articulatin gsurfaces o f two metatarsals from Malta is very n o ticeable . Muchvariatio n In size is indicated - by the Maltese sp ecimen s .

Arvico la me li ten sis ,‘

sp . n ov. Crown View o f first an d se con d right l owermo lars . En larged x 1 5 diam . a . an terior l o op ; c . t. clo sed trian g l e s ;

p . p osterior tran sverse lo op .

There is in the British Museum the distal en d o f a humerus(M. 8159 ) from the Pleisto cen e o f Corsica ,

which seems to agreeclosely in size with the Maltese form . No fox is foun d livin g inMalta at the presen t day ,

the o n ly lan d carn ivores bein g Mustela

n ivalis boccamela an d M . afm'

can a,the latter possibly in troduced

through human agen cv .

l

REPTILIA .

Reptiles are represen ted by a few fragmen ts o f carapace , ascribedto Lutremys europ aza ,

an d by several limb bo n es , p elvic bon es , twove rtebrae

, an d the base o f a skull o fBufo vulgaris , Laur . These latterspecimen s have been kindly examin ed by Dr . G. A . Boulen ger,

who co n siders that from the characters o f the sacral vertebrathey may be confiden tly assign ed to this sp ecies . Previously n o

sp ecifically iden tified remain s haVe been reco rded ; Leith Adams

in his List ” 2 men tio n ed o n ly Batrachia sp . Fro gs or Toads, sp .

”

It is in terestin g to n ote that apparen tly n o toad o ccurs in theMaltese Islan ds at the presen t day ,

the o n ly batrachian bein gDiscog lossus p ictus Otth .

Se e Mil ler , Cat. Mamm . West. Europ e , 1 9 1 2 , p . 414 .

Quart. Journ . Ge o l . Soc . , vo l . xxxiii , 1877 , p . 1 77 .

3Se e Dr . Gul ia , lo c . cit.

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F. Dixey— Later i tizati o n i n Si erra Leon e.

2 . (i) LATERITIZATION OF THE NORITE . (Pl . 111, Fig .

The'

coun try rock o f the Co lony is a medium-

grain ed n oriteasso ciated with which is a relatively small developmen t of a coarsen orite and an

'

ap litic variety ; the medium -

grain ed type o ffers thebest mean s of fo l lowin g the process o f lateritization .

In con sequen ce of ‘

rapid erosio n induced by high relief,laterite

formed in situ has been un able to accumulate to an y co n siderabledepth excep t in special circumstan ces . On valley - sides,hill—crests,an d co ls

,the laterite is rarely more than a few in ches deep . On

roun ded hills and gen tle slop es the coun try rock crops out in a

characteristic man n er as n umerous large boulders and crags, o r

even low iso lated roun ded surfaces . The outstan din g charactero f these various masses is due in all cases to lateritization

,which

progressed alon g master j o in ts . The lateritized p ortion was morereadily removed by ero sive agen cies , an d the masses of un alteredrock were left stan din g in relief . The masses of rock expo sed inthis way exfo liate in thin shells an d gradually assume a roundedform . Their exp o sed surfaces are either fresh or covered with o n lya thin skin o f laterite . Where the ro ck is closely j o‘in ted,

lateritization

pro ceeds un iformly throughout and extends to a dep th o f severalyards . Examp les o f this o ccur over part o f the gen tle slop e 1 o nwhich the W.A .R . camp stan ds

,n earWilberfo rce;an d in the valley

o f the Co n go south - west o f Freetown . The dep th o f lateritizatio n

was so great o n the right bank o f the Co n go at a height of about500 feet O .D . that a pro j ect for buildin g a small dam acro ss thevalley ended in failure , because it would have been n ecessary forthe dam to rest everywhere up on so lid ro ck

,an d the co st o f this was

prohibitiveA clearin g was made up the steep valley sides just above a n arrow

go rge on the left ban k the n orite was exp osed under a thin covero f laterite

,but o n the right an excavation cut through 12 feet o f

laterite befo re exp o sin g the n o rite,

an d even when exten dedlaterally met o n ly the altered ro ck . The alteratio n had pro ceededalon g j o in ts un til o n ly co res o f un altered rock were left the coreswere in the form o f slabs because o f the platy j o in tin g prevailin gin this place . The slabs or co res were surrounded by more or lessco n cen tric lay ers o f red laterite

,which became more irregular in

shap e outwards . Sometimes all that remain ed o f the o rig in al mass

was a red gho st with co n cen tric lamin ation and an irregularoutlin e .In most localities in the Co lo n y the co re o f a lateritized massI

tends to become con tinually mo re roun ded in form as it dimin ishes"in size . But where the n o rite is banded lateritization sometim

1 Cf. Pro fe ssor Lacro ix , The formation o f a Con tin uous crust dep en ds on

defin ite top ographical co n dition s (ho rizontal p late au o r g en tle slop e of groun d ) .Fe rmor, The Work o f Professor Lacro ix on the Laterite s of Fre n ch Guin e aGEOL . MAG .

,19 15 .

F. Dix ey— Later i tie a ti on i n Si erra Leon e . 2 13

proceeds rap idly alon g certain ban ds,which when dipp in g at a high

an gle are altered to a con siderable dep th . A n umber of little covesand a series o f parallel reefs run n in g out obliquely from the sho reowe their o rigin to the removal o f such weathered ban ds by waveaction . Examp les can be seen about Ken t and n ear AberdeenCreek .

It is p ossible to trace in the hand sp e cun en the chan ge from a

core o f un altered n o rite to the outer zon e o f red - brown laterite(“

gibbsitic laterite o f Pro fesso r Lacro ix 1

) . The grey co re isen clo sed by a pale cream - co loured halo with brown pseudomorphso f the pyroxen es . This pale halo gives p lace gradually throughyellow an d then brown to the red - brown

_

outer zon e the halo an d theouter zon e correspo nd resp ectively to Professor Lacro ix ’s

,

“ zon eo f leachin g and zon e o f co n cretion The transitio n from coreto halo is a rap id o n e and takes p lace within 02 in . The co loursof the halo an d succeedin g zon es are due to a whitish a lterationproduct o f the felspars, which becomes stain ed to an in creasin gdep th as the ferromagn esian min erals decomp o se . As the alteratio nprogresses the individual crystals gradually become un reco gn izableand the mass itself becomes crowded with small“ con cretio n s and

p ierced by n arrow ferrugin ous vein s,un til fin ally it forms coarsely

porous red laterite . This seco n dary laterite bears close resemblan ceto that fo rmed from detrital dep ositS .

3

As regards individual min erals fe lsp ar is the first to be affected .

It passes in to a white opaque alteration product , which spreadsalon g the cleavage cracks , an d for a time leaves flakes o f the min eralfresh an d un altered .

‘ Then a clear white recrystallizatio n sets upalon g the o ld cleavage cracks an d the remain in g parts o f the crystaldisso lve out

,resultin g in a framewo rk of parallel p lates studded with

minute co lourless crystals (probably gibbsite ) . Later iro n stain in gcommen ces

,an d the pseudomorph gradually

'

breaks up . Diallage

chan ges in co lour from almost black to brown at a very early stage ,and with the rhombic pyroxen e causes a mo ttlin g o f the lightco loured halo ; it is then gradually pseudomo rphed in paralle lbrown scales

,exceedin gly fin e

,and p o ssessin g an earthy lustre .

The rhombic p yroxen e develop s a close , p laty structure , an d retain sits bron zy lustre to a late stage . The iron - ore is reco gn izable , andapparen tly un altered lo n g after all the o ther min erals havedisapp eared . Olivi ne is n o t recogn izable after lateritizatio n has

commen ced .

1 Op . cit., p . 35 .

2 Op . cit . , p . 34 .

3 Cf. Arsan daux Toute s les formation s latéritique s mon tre n t deuxzon es (i ) La p remiere zon e , con tig iie ala ro che o rigin e lle e n rep roduit e xactemen t la structure ; e lle e n con stitue un e vé i itable p seudomo rphose ; le s

fe lspaths de la ro che fral che so n t remp lae és par un e matie re blan che ; le s

elemen ts co lorés par du sesquio xyde de fe r. (ii ) La se co n de zon e , sup erp oséea la p remiere e st dep ourvue de tout o rdon n an cemen t de ses élémen ts con

stitutifs”

(Handbuchder regiona len'

Geo log ie vii,6a

, p .

2 1 4 F. Diaeyfl La ter i tizati on i n Si er ra Leon e

(ii) ALTERATION OF NORITE RICH IN IRON .

Lateritization proceeds -very readily where the n orite is rich indissemin ated magn etite (titan omagn etite) , but it go es on Slowlyif the p rop ortio n o f iron be in creased beyo n d a certain p o in t . Thisis illustrated on the foresho re west o f Aberdeen Creek , where certainin clin ed bands in the n orite have been thoroughly lateritized forman y yards alo n g their outcrop

,an d seams of magn etite in them,

up to 2 in ches thick,run practically un altered from n o rite in to

laterite . Some o f the seams co n tain a little felspar in parallelarran gemen t with the magn etite . In such cases the magn etite iso ften left as a sp on gy mass o n the weatherin g o f the felspar . Furtherwithin the lateritic masses there o ccur more o r less spherical co resof iron —rich n orite , en clo sed in con cen tric shells such coresapparen tly owe their un altered state to a high iro n con ten t .In addition to the seams o f magn etite in the n ormal n orite , there

o ccur locally in the coarse n o rite irregular crystals an d small sp on gymasses o f magn etite which also remain un altered when the en closin grock is lateritized . Go od examp les of these masses

,an d o f crystals

ran gin g up to 3 in ches in len gth , can be seen in coarse n orite exp osedo n the foreshore immediately south of York .

3. LATERITIZATION OF GRANITIC ROCKS .

The so lid ro cks o f the Pro tectorate have been lateritized to a

con siderable dep th in man y p laces . Where they rise above thePleisto cen e dep osits of the p lain they are frequen tly seen in railwayan d road cuttin gs to be lateritized to a dep th o f 15 feet, an d ’

some

times to 20 o r even 30 feet (Pl . III,Fig . In the more hilly and

moun tain ous parts o f the coun try ,esp ecially in the n orth

,laterite

is n o t n early so well develop ed . The moun tain sides are o ften verysteep an d bare

,and un covered by vegetatio n excep t fo r a few tufts

o f grass , and even in the bro ad valleys op en in g out o n to the plain ,

an d on the n orthern part of the p lain itself, the laterite o ccurs on lyas patches of gravel . The co n dition s In this part of the coun try are

similar in man y respects to tho se o f the moun tain districts o f

Mo zambique,co n cern in

gwhich Dr . A . Ho lmes states : 1 It is

imp ortan t to n o tice that'the steep slop es of the in selberg peaks an dmoun tain blo cks are always free from depo sits of the lateriticcon stituen ts . Solution s must certain ly exist which o n evap orationwould give rise to such dep o sits , but the mountain rain s an d n ight “dews suffice to carry them down to the debris - covered p lateausurface below

,where they co n tribute to the formation o f the lateritic

earths which so frequen tly sweep aroun d the base of the hills .

”

The lateritization o f the gran itic rocks pro ceeds as fo llows : therocks become broken down in to small masses by weatherin g at thesurface an d . by decomp osition alon g j o in ts an d the less resistan tban ds ; the decomposition

“ then proceeds inwards from the outer1 The Lateritic Dep osits ofMo zambique GEOL. MAG. , 19 14 , p:534.

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2 1 6 F. Dix ey— Later i ti za ti on i n Si erra Leon e .

o f the railway run n in g between Waterlo o an d So n go . The depositso f the Bullom Sho re ran ge from co arse felspathic san d-

s to almo stpure clays . Lateritization is most p ro n oun ced in the san ds an d

dimin ishes i n the mo re argillaceous beds un til it is practicallyn on - existen t in _pure clay . The probable exp lan ation is that thesan ds allow surface waters to p erco late through them mo re freely ,

an d also that they con tain a much higher proportio n o f iro n in 'theform o f grain s o f magn etite .The typ ical laterite exp o sed alon g the cliffs an d in stream beds

is a red - brown to bright red sco riaceous ro ck , moderately hard,an d

in the han d sp ecimen co arsely p orous ; the diameter o f the p oresis about 04 in . The texture o f the walls surroun din g the po res isua lly compact, the surfaces bein g smo o th o r rough acco rdin g toin creasin g Size an d n umber o f the san d '

grain s .. The laterite lo cally

co n tain s small masses,len ticles

,an d streaks

,rarely exceedin g 2 feet

in len gth , Of lo o sely compacted y ellow san d,mixtures o f san d

an d magn etite grain s cemen ted in to a purp le mass,an d o f clay co n

tain in g an ythin g from mere iro n stain in g to a very high prop ortiono f haematite an d limon ite . When a small lump o f the laterite isexp o sed to the weather fo r a lo n g time it acquires a smo o th lustroussurface

,dark—brown to black in co lour . The p ores in the laterite

o ften remain o f un iform character to a dep th o fman y yards bey o n dthis dep th the p oro

'

us mass passes in to a red compact san d p iercedby irregular streaks and p ip es cemen ted by iron o xides .

This p orous laterite forms a hard crust about 10 feet thick at

the top o f the Pleistocen e dep o sits o f the p latform; it is exp o sedalon g the upp er part o f the cliffs an d as huge “

fallen blocks at

their fo o t .Orig in of the Scoriaceous Laterite .

— Lateritizatio n dep en ds largelyup o n the amoun t o f Iro n origin ally co n tain ed in the beds subj ect

,

to the alteration,an d also upo n the ease with which water can

p erco late through them Just as the modern marin e san ds varycon siderably in their degree of fin en ess and the p rop ortio n of ironan d silt they co n tain

,so p robably did the Older dep o sits n ow up

raised to form the Pleisto cen e platfo rm .

The san dy dep o sits offer the best mean s o f Observin g the chan gesinvo lved

,which were as fo llows :

Owin g to the breakin g down an d hydration o f the iron by thecombin ed effects o f waters an d vary in g temp eratures, _ p ale y ellowsp o ts were p roduced in the beds . The material formin g the sp o tsharden ed in to little lump s about the size of a p ea as these lump sgrew larger their cen tres became brown ,

an d then red, p o ssibly as'

the result o f in creasin g dehydration . Con sequen tly , at an y later stage ,they p o ssessed co n cen tric co lour—zon es in red

,brown

,an d y ellow .

In time the lump s , -

o r con'cretio n s

,co alesced in to irregular n odular

masses . These m asses fin ally formed a thick crust an d . arrestedl

the co n cretionary pro cesses by causin g the waters to flow in defin itechann els. through o r over the surface o f the crust

,in stead “

o f

F. Dix ey— ‘

La ter i ti zati on i n Si er ra Leon e .

perco latin g through the cen tre mass . If at this stage the ro cksare exp osed to the a

'

ction of ero s1ve agen cies , the un altered san ds

between the con cretion s are washed out,an d on ly a coarse red mass

remain s ; this mass ten ds to become harder an d more p orous as

time go es o n . This pro cess is illustrated at an y p lace where cliffsformed o f Pleisto cen e dep osits are bein g eroded by the sea ,

for the

waves con tin ue to cut out the so ft san dy 'beds under the crust un tilit falls to the fo o t o f the cliffs in large y ellow - brown masses. Whenn ewly fallen these masses are rubbly _

and easily broken ; so o n,

however,they commen ce to harden an d the so ft material between

the con cretion s is wo rn away ,leavin g on ly the red, p o rous laterite .

When the iron is distributed lo cally an d irregularly it forms ferrugin ous strin gs an d p ip es traversin g a mass o f partially compactedsan d .

In the san dy clays the chan ges take p lace more slowly ,and the

growin g ,ferrugin ous con cretion s do n ot harden un til a much later

stage in the gen eral alteratio n is reached . Mean time,the partly

altered beds remain un cemen ted an d brightly mo ttled in '

purp le ,red

, brown ,and '

y e llow . As compared with laterites fo rmed fromless clay ey beds the con cretion s in the sandy clay are smaller

'

an d

the resultin gmass less coarsely porous .

The thick beds o f white,cream

,o r grey clays do n ot alter

appreciably ,excep t to acquire irregular films o f haematite due to

the infillin g o f desiccation cracks . The red an d y ellow or red an d

white mo ttled clays which co llect lo cally in passes an d in valleysowe their co lourin g to the above p ro cesses ; they do n o t con tainen ough ' iron to produce hard con cretio n s, an d co n sequen tly theyremain p lastic while wet an d become hard an d compact when dry .

(11) LATERITIC IRON - ORES .

The detrital laterite passes lo cally in to lateritic iron - o re by in creasein the p ercen tage o f Iro n oxide . Such iro n~~ores are well developedalo n g the in n er margin o f the coastal p lain en circlin g the Co lon y ,

an d o ccur prin cipally in the n eighbourho od o f Devil Ho le,n ear

Waterlo o . They were derivedb

o rigin ally from the magn etitewhich is such an imp o rtan t con stituen t o f the

n orite mass fo rmin g the Co lon y . They were accumulated at an

earlier p eriod in the same way as black san ds are accumulatin g o n theCoast to - day . The sea fo rmerly reached as far as the in n er margino f the presen t p lain ,

an d as the streams brought down the productsof weatherin g from the hillsides the grain s o f iron - ore were depo sitedprin cipally n ear the shore

,an d the lighter min erals , chiefly felspar

an d weathered ferromagn esian crystals , were carried further out,

to build up the p lain as'

n ow existen t . Co n sequen tly the beds n earthe o ld shore lin e co n tain a higher pro p ortio n o f iro n than tho sedistan t from it

,an d a1 e sufficien tly rich lo cally to rank as iro n o res .

The o res have attain ed their presen t co nditio n through the oxidatio nand hydration o f a great prop ortion o f the titan iferous .magn etite .

2 18 F. Dir ey— Later i ti zation i n Si erra Leon e .

The grade an d structure of the ores vary co n siderably . Thecommon variety is p iso litic the cores o f the p iso liths are black an ddeep red

,the en clo sin g part red,

an d the in terstices between thep iso liths are more or less filled with limon ite . An o ther varietyis fin ely mo ttled in purp le , red,

an d y ellow ,an d shows o n ly a slight

developmen t of the p iso litic structure . The riches-t o res are madeup o f n odules o r small masses o f almost un altered titan iferousmagn etite , whereas the p o o rest ores are . con cretion ary an d containon ly a low p ercen tage o f iron ,

chiefly in the form o f thin limon iticco atin gs to the co n cretio n s .

A fragmen t o f o re exp o sed o n the surface o f the gro undweathersin to a roun ded n odule

,and assumes a smo o th p o lished ferrugin ous

skin o f a dark - brown co lour .

The Devil Ho le ores form a belt 400 to 500 yards wide , run n in gparallel with the fo o t of the hills the belt has been traced for threemiles

,and p robably extends over a much greater distan ce . Several

small shafts an d a tren ch 15 yards lo n g were excavated in the dep o sitwith ' the help o f exp lo sives ; the sectio n s showed _ so il an d subso ilup to 15 in ches in thickn ess

, p assin g downwards in to a rubbleco n tain in g large and small co arsely p o rous lump s . Un derly in g therubble were large masses of a compact o re ,

which lo cally assumedan irregular p laty structure . The ore was proved to a dep th o f

8 feet,an d it probabl y co n tin ued to a much greater dep th the re are

thus well over to n s o f o re in dicated in this dep osit . Thedep osit run s parallel with the Sierra Leon e Governmen t Railway ,

and is practically adjacen t to it moreover,sin ce it isseparated from

the mouth o f the Bun ce River on ly by a n arrow strip Of the p lain ,

about a quarter o f a mile wide,the ore could be shi pp ed directly

at very little co st .Mr . G. F . Sco tt Elliott 1 gives the fo llowmg an alysis of a samp le

o f the ore from this district the hills behind Sierra Leon eProtoxide of iro n

Pe ro xide o f iron

Titan ic p e roxideChromium p e roxideMan gan e se p e ro xideSilica an d sil icates

SulphurPhosphorusLime

MoistureOxygen an d loss

Other an aly ses 2 o f rep resen tative samp les show that the amoun to f titan ium they con tain varies from 3 to 20 p er cen t , an d sin ce ,under presen t condition s, steel can n o t be made at a profit from

1 Co l . Re p . Misc No . 3 (Sie rra Le on e ) , 1893, p . 6 .

Kin dly made for the Ge o logical Survey by the W1gan Coal an d Iron

Compan y , Ltd .

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220 F. Diazey— Later i ti zati o n i n Sierra Leon e .

4 . .The gran itic ro cks o f the Pro tectorate are frequen tly lateritizedto a dep th .o f 15 feet

,and sometimes even to 30 feet . Nevertheless

laterite is o n ly slightly develop ed in the in selberg moun tain districtso f the n orthern part o f the coun try . Lateritization of gran iticro cks pro ceeds as fo llows : the ro cks decomp o se in to a whitekao lin itic product, which passes in to brown lateritic clay zo n e o fleachin g this lateritic clay then develops in to laterite zon eo f co ncretion There is a p rogressive chan ge from the un alteredro ck to the laterite crust

,the - gran itic ro cks in this resp ect presen tin g

a marked co n trast to the basic ro cks .

5 . Lateritization affects detrital dep osits also, particularly the

Pleistocen e sands and clays o f the coastal p lain . The phen omen o nis most p ron oun ced in the felspathic sands an d dimin ishes in themore argillaceous beds un til it is practically n on - existen t in pureclay . The typ ical lateritite is a red - brown scoriaceous ro ck ,moderately hard ,

and in the hand sp ecimen co arsely p orous . Itforms a crust about 10 feet thick at the top of the

'

Pleisto cen e

beds . This lateritite 1s Indistin guishable from the laterite derivedfrom o ther rocks .

6 . The scoriaceous . laterite (lateritite )was produced by the growth’

an d'

ultimate coalescen ce o f n umerous small ferrugin ous con cretion s,fo llowed by the removal o f the so ft material between the co n cretions7 . The laterite formed from detrital dep o sits passes lo cally in tolateritic 1ron o re by mo i ease in the p ercen tage of 1ron oxide . Suchiron ores are well developed alo n g the In n er margin o f the coastalplain en circlin g the co lon y ,

and o ccur prin cipally in the n eighbourho od o i Devil Ho le , n ear Waterlo o . They were derived o rigin allyfrom the titan omagn etite which en ters largely in to the comp o sitio nof the n orite , and they are co n sequen tly very rich In titan ium .

8 . Lateritizatio n i s frequently an imp o rtan t factor in thep roductio n o f caves and subterran ean chan n els

,owin g to the ease

with which the un co n so lidated material is removed from ben eaththe thick hard crust o f laterite .In con clusio n

,I have great p leasure in reco rdin gmy indebtedness

to Professor A . H. Cox ,o f Un iversity Co llege , .Cardiff, who kindly

made man y useful suggestion s durin g the writin g of these n o tes .

EXPLANATION OF PLATE III .

FIG.—Late ritized n orite ,

in railway cuttin g , Wilbe rforce , Sie rra Leon e .

The pho tograph il lustrate s a late stag e in the lateritizatio n of two blo ckso f n o rite . Each“block is n ow represen ted on ly by a co re o f un altered n orite

e n clo sed in co n ce n tric she l ls o f late rite . The o rig in al upp er surface o f

the right - han d blo ck is in dicated by the p osition Of the hamme r.

FIG . 2 .

—R- e sidual late rite derived from gran ite ,rai lway cuttin g n e ar Baoma ,

Sierra Le on e . The un altered gran ite forms a ridge which trave rse s thecutting oblique ly from right to l eft.

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222 J. ReidMorr— Ag e of Ear liestPa loeo l i thi c Imp lemen ts.

an d,further

,I would wish it to be clearly understo od that the

views expressed in this n o te are based so lely upon discoveriesmade in the Ipswich district

,an area with which I am in timately

familiar .

NEOLITHIC .

— On the high ground n ear Ipswich a flin t arrow - headwas found in the surface so il . 1 In the bo ttom o f the Gipp in g Valleya chipp ed an d p o lished flin t ax e has been discovered recen tly un der3 to 4 feet o f p eat surface so il . (Man

,in course

'

o f publicatio n . )UPPER PALE OLITHIC Magdalen ian .

— No certain traces found ,

un less a flo or in Ivry Street, Ip swich , buried un der 2 or 3 feet of

ston eless snuff - co loured san d, can be referred to this cultural phase .

This flo or is situated up on the p lateau .

2

So lutrian — A patin ated and ro lled early So lutrian flin t bladewas found in gravel at the site o f the Ipswich Electric Power Station ,

situated in the bo ttom o f the Gipp in g Valley .

Two Early So lutrian blades were foun d in hill - wash overly in gthe Aurign acian flo or in Messrs . Bo lton Co .

’

s brickfie ld,Hen ley

Road,Ipswich

f This hill - wash was probably laid down durin ga p eriod o f low temp erature , an d may p erhap s be regarded as theequivalen t , on the high ground, of the river-

gravel in the Gipp in gValley co n tain in g a So lutrian blade . The p eriod o f low temperatureresp on sible fo r these dep osition s may have been that kn own upon

the Co n tin en t as the Wu'

rm.

AURIGNACIAN .

I

— A well marked flo or,con tain in g Aurign acian

flin t imp lemen ts, covered by the above - men tion ed hill wash , and

restin g up on loamy sand in Messrs . Bo lton Co .

’

s briclifie ld,

Ip swich .

5

LOWER PALZEOLITHIC Upp er Mousterian .

— A well - marked flo or,con tain in g Upp er Mousterian flin t imp lemen ts , gen erally coveredby p eat or loamy sand

,an d resting sometimes upOn Chalky Boulder

clay in Messrs . Bo lto n 85 Co .

’

s brickfie ld,Ip swich .

6

Middle Mousterian .

— A flo or with Middle Mousterian flin timp lemen ts an d abun dan t remain s of rein deer

,occurrin g in loam,

an d un der 4 feet o f alluvium and 8 feet o f gravel (the dep o sitcon tain in g the Early So lutrian blade above men tion ed) at the siteo f the Electric Power Station ,

Con stan tin e Road,Ipswich .

7

Lower Mousterian .

“ Flin t imp lemen ts found In Chalky Boulderclay at Bo lto n 85 CO.

’

s brickfie ld, Ip swich , an d Maso n ’

s Cemen tWorks, Claydon .

a

The Chalky Boulder clay may be referable to the Riss glaciatio n .

1 Mo ir,Journ . Roy . An thr . In st. , vo l . xlvii 19 17, pp . 406—7 .

2 Mo ir, Pro c P .S E .A. vo l . i , p t . iv, p p . 475 9 .

3 Han cox , Proc . Suff . In st . Arch . an d Nat . Hist . , V o l . x i , p t . 1 an d pt . ii , fig . 4 .

1 Mo ir, Journ . Roy . An thr . In st . vo l . xlvii,19 17, p p . 405 6 .

5 Ibid . , p p . 367—4 12 .

5 Ibid .

Mo ir, Man ,vo l . xviii

,No . 7

, July ,19 18 .

8 Mo ir,Pro c . Suff. In st . Arch. an d Nat. Hist , vo l . x

'

vi, p t . ii , p p . 98—134 .

J.Re idMe ir— Ag e of Ear li estPa laeo li thi c Imp lemen ts. 223

Acheulean - Late Acheulean flin t implemen ts foun d byMissN. F .

Layard in a silted - up chan n el in the. p lateau at Foxhall Ro ad,Ipswich .

1On e such sp ecimen (n ow preserved in the British

Museum ,Blo omsbury ) , recovered by me o n the eastern side o f the

chan n el , occurred up on san d overlain by co n torted material classedby Bo swell as ‘‘

Upp er Glacial .

2

imp lements were found in the Middle Glacial Gravel at Bo ltonan d Co .

’

s brickfie ld,Ipswich .

3

This gravel may p erhap s be regarded as o f Minde l - Riss in terglacial age .

The discoveries made up on the Mun desley co ast, and further

researches carried out this y ear at Cromer,ten d to Show that

the glacial gravels overly in g the Till con tain derived Chellian flin timplemen ts

,and from the fin din g o f certain flakes

, etc .,in the

Cromer Fo rest Bed it is suggested that this dep o sit is the realChellian horizo n . The Till an d associated beds may p o ssiblyrepresen t the depo sition s o f the M inde l glaciatio n The Chellianimp lemen ts may therefore be o f Gun s M in de l in terglacial age .

PRE - PALZEOLITHIC —The flin t imp lemen ts foun d i n the detritusbed ben eath the Red Crag o f Suffo lk .

4 These sp ecimen s, which Iregard as of pre Chellian typ es , are frequen tly striated . It IS p ossiblethat these striae were imp osed durin g the Gun z glaciatio n (the earliestglacial ep o ch reco gn ized by Pen ek) , an d the large blo ck o f darkred p

I

orphyry ,weighin g about a quarter o f a to n ,

’’

seen by Prestwichto be restin g up o n the Lon do n Clay at the base o f the Co rallin eCrag at. Sutto n n ear Wo odbridge , may have been tran sp o rted bythe Ice o f this glacial ep isode .The very

I

p rimitive edge - trimmed sto n es,kn own as

' eo lithso ccur as deep ly i ro n - stain ed an d ro lled derivatives in the MiddleGlacial Gravel in Messrs . Bo lto n 82: Co .

’

s brickfie ld,Ipswich .

6

These sp ecimen s are regarded as represen tin g the earliest effortsOf man to fashion flin ts

,an d as bein g the precursors o f the Sub Red

Crag artefacts .

It is also believed that the Sub - Red Crag ro stro - carin ate flin timp lemen ts develop ed in to the earliest p latessiform an d batifo rm

Chellian imp lemen ts .

The discovery o f Acheulean flin t imp lemen ts at Hoxn e 9 an d at

Foxhall Ro ad,Ipswich , 1° o ccurrin g in dep o sits restin g up o n Boulder

1 Journ . Roy . An thr . In st.

,vo l . xxx111

,1903.

I

2 Pro c . Ge o l . Asso c . vo l . x’

xv p t . 111, p . 136 .

3 Mo ir,Journ Roy . An thr . Inst. v, o l . xlix , 19 19 , pp. 74—93.

4 Mo ir, Pro c . Prehis . So c . East An glia,vo l . 1

, p t . 1 pp 17 43,an d o the r

pap ers .

5 The Structur e of the Crag beds, Lon don ,1871

, p . 1 17 .

6 Mo ir, Proc . P .S .E .A,vo l . 1 p t . iii , pp . 307—19 .

7 Mo ir, P -re pa lwo li thic Man, p p . 2 1 34 . Ha1 rison , Ip swich .

8 Mo ir,Phi l . Tran s ,

B, 19 19 , p . 209 .

9 Brit. Asso c . Rep o rt, 1896 , p . 12 .

1° Journ . Roy . An thr . In st . , vo l . xxxiii , 1903

224 Pr of. S. H. Rey n o lds fi Serp eoi tifn/ e rte-ctr We lls

, Somerset:

clay , are o f imp ortan ce in this in quiry (it seems that there are twoglacial dep osits at the latter p lace , o n e above the palaeo lithic horizo nand o n e below it) , an d it is suggested that, at bo th these places

,

o ccur patches of a o n ce widespread sheet of glacial clay o lder thanwhat IS kn own as the Chalky Boulder clay ,

an d p erhaps referableto the Mi ndel glaciation .

' The well kn own section at High Lodge ,Mildenhall , where a Mousterian brick earth in terdigitates with a

mass o f Chalky Boulderfielay ,represen ts probably a remn an t o f the

Mo usterian dep osits , man y o f which were p loughed up by the iceand furn ished the imp lemen ts o f this culture found in theBoulder—clay .

Professo r J . E . Marr,

who has visited Ipswich and seen an d

examin ed the eviden ce at my disp o sal , permits me to say that heco n siders a prima facie case has been made out for the aboveco rrelatio n ,

so far as the dep o sits o f East An glia are con cern ed .

He con siders, however, that the referen ce of certain depositsto the p eriods o f glaciation up o n the Con tin en t requires furtherinvestigatio n . With this co n clusion I am in agreemen t .

On the O ccurre n ce o f Picritic Se rp e n tin e at Ebbo r,n e ar We lls, Som e rse t.

By SIDNESI

Z H. REYNOLDS, M.A ., Sc .D . , Professor o f Geo logy in the

Un iversity o f Bristo l .N October, 1904, Mr . H. E . Balch , of Wells, forwarded somepieces o f trap from Ebbor to the late Mr . H. B . Woodward,

who han ded them to Dr . J . S. Flett fo r examin ation . At a slightlylater date p ieces were given to me by Dr . T . F . Sibly,Who was thenat work in the Men dip -s .

It was at on ce clear that we had here an ultra - basic rock, andDr . Flett

,whose description will be quo ted immediately , p o in ted

out the practical iden tity o f the ro ck w ith that from Cli‘cker Tor,Men hen io t , Cornwall , when ce he believed the sp ecimen s had beenderived . The ro ck o ccurred in the fo rm of small p ieces, rarely morethan 2 21 in ches lo n g , scattered over quite a limited area about a quartero f a mile N.W. o f Wo okey Ho le an d due south o f Lammas Wo od .

The very great maj o rity were found m a field due south of Lammas

Wo od,a few p i eces were foun d 1n the n ext field to the west, an d o n e

in the adjacen t field to the east . The area li-es s lightly below the400 ft . co n tour - lin e . The p ieces are all fairly an gular an d com

parative ly little weathered . Probably over 200 p ieces o f the rockhave been foun d here from time to time ,

o n DecemberI myself foun d twen ty - o n e p ieces scattered over

'

a small space inthe cen tral part o f the eastern third o f the chief field . I havefoun d o thers o n subsequen t o ccasio n s, but fo r some years n ow

have n o t been able to find an y more . Mr . Balch , however, rep orts1 Sturge , Pro c .

'

vo l . i , p t . 1, p p . 43—105 .

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226 Prof. S. H . Rey n o lds—f Serp en ti r/ e n ear Wells, Somerset.

South Wales,to Devon and Cornwall , an d which is gen erally

attributed to the work of the Plio cen e sea .

1 The suggestion is

therefore made that the p icritic serp en tin e is derived from a boulderdropp ed from an iceberg floatin g in the Pliocen e sea .

Dr . J . S. Flett’

s description o f the sp ecimen s sen t to Mr . H. B .

Wo odward by Mr . Balch is as fo llowsAugite Picrite, passin g in to serp en tin e .The han d sp ecimen s have a dark green co lour an d a smo oth

fracture,with slightly un ctuous fe e] . The micro scop ic section shows

that the ro ck con sists mo stly o f rounded grain s o f ohvme,decom

p o sin g in to aggregates of y ellow an d green serp en tin e . These arepartly embedded in or surroun ded by irregular p lates o f pale brownaugite , eviden tly o f later fo rmation than the o livin e

,o n which it

is to some exten t moulded . Olivin e forms at least o n e - half o f thero ck

,an d hen ce typ ical lustre mo ttlin g is n o t develop ed . A little

seco n dary horn blende is also p resen t . In all its features this ro ckis iden tical with the p icrite o f Clicker To r, Menhen io t, Cornwall,from which it has probably been derived .

”

The silica p ercen tage as determin ed by Mr . E. M. Lan e in 1906in the chemical labo rato ry o f Un iversity Co llege, Bristo l, is 306 6 .

The sp ecific gravity as determin ed bo th by Mr . E . M. Lan e an dMr . F . S. Wallis is 2 71

,the relative lown ess bein g n o doubt

attributable to the weathered character o f the ro ck .

1 Se e Barrow, Quart. Journ . Ge o l . So c. , vo l . lxiv ,1908 , p . 384 .

REVIEWS.

THE PRINCIPLES OF ECONOMIC GEOLOGY . By WILLIAM HARVEY”EMMONs, Ph .D . pp . xviii 606

,with 210 text - figures . New

York : McGraw- Hill Bo ok Compan y ,In c . Lon don : Hill

Publishin g CC .,Ltd . 1918 . Price 243. n et .

IN this bo ok the author presen ts a persp ective of the presen tp osition of the scien tific kn owledge of metalliferous an d n on

metalliferous min eral deposits , with the excep tion of fuels and o il .

However,the amoun t o f space devoted to the n on - metalliferous

deposits amoun t to on ly about 70 pages out o f 600 ,and it is to all

in ten ts and purp o ses a textbo ok o f the geo logy o f metalliferousmin in g . The first twen ty - on e chap ters of 290 pages are devo ted toa discussion o f gen eral prin cip les, while the rest o f the bo ok isoccupied by descrip tion s o f actual “

o ccurren ces . classified un der theheadin gs of the various metals or n on - metals .

This is perhaps scarcely the place to discuss the gen eral questionof the rival classificatio n s o f ore—depo sits

, gen etic or chemicaln evertheless it may be allowable to p o in t out that the method hereadopted presen ts man y practical advan tages , an d certain ly makesreferen ce easy . A gen etic classification

,such as has been adopted

in most of the larger German bo oks,is p erhaps more strictly

scien tific,but it is certain ly co n fusin g to the learn er, sin ce it brin gs

together a who le lot of dep osits which have little in common from thep o in t o f View o f the min er and metallurgist, however similar theirorigin may be . On the o ther han d an arran gemen t by metalsgroups in on e chapter or section dep osits that may have been formedin a great variety o f ways, an d a sp ecial difficulty presen ts itselfin the case of ores worked for more than o n e metal . It is clearthat an ideal classificatio n has n ot y et been evo lved, an d from then ature of the subj ect it probably n ever will be . The who le matteris a question o f the balan cin g o f advan tages an d drawbacks, an d inour op in ion Pro fessor Emmon s has acted wisely in cho osin g as he

has don e .The earlier chapters afford an admirable discussion of the gen eral

geo logical, min eralogical , chemical , an d. physical prin cip les un derly in g the formation

'

o f wo rkable min eral deposits . The metalliferousdep osits are classified un der eight headin gs, as magmaticsegregation s, p egmatite dep osits, con tact - metamorphic dep o sits,dep osits of the deep vein zon e , dep osits formed at moderate depths byhot so lution s, dep o sits fo rmed at shallow dep ths by ho t so lution s,dep osits formed atmoderate and shallow depths by co ld andmeteoricso lution s

,and sedimen tary dep osits . This subdivisio n seems some

what elaborate it is very doubtful , for examp le , whether an y realdistin ctio n can be drawn between pegmatites and vein s o f the deepzon e

,and it is well kn own that certain pegmatite dykes can be

fo llowed laterally or vertically in to o rdin ary quartz vein s, as indeedis exp licitly admitted by the author, who also recogn izes clearly

228 Reviews— The Pr i n cip les of Econ om ic Geo logy .

that most o f his groups grade in to each o ther by impercep tibletran sition s . The who le question really hin ges on the exten t to whichthe . circulation o f meteoric waters has taken part in the pro cesseso f ore - formatio n

,and as is gen erally kn own more imp ortan ce is

assign ed to this agen cy in America than in Europ e , perhaps main lyowin g to the influen ce o f “

Posepny. In man y American writin gsthere are still stron g eviden ces o f the survival o f the lateral secretiontheory of San dberger, an d indeed somethin g very like it is gen erallyput forward in exp lan ation o f the origin o f the lead- zin c dep ositso f Missouri a n d Kan sas . Still more commo n is the con ception of

vein—formation by downward movemen t of meteoric waters in toegio n o f high temperature where metals are disso lved and carried

to a higher level by subsequen t rise o f the heated so lution s .

Acceptan ce of this theo rv is ren dered difficult , amon gst o thereviden ce

,by the fact that man y deep min es are dry in their lower

levels . The common o ccurren ce o f distin ct ore - zo n es around an d

above in trusion s is also difficult to exp lain on this hypo thesis . Thesequestion s are discussed at len gth by Professor Emmon s

,who gives

a mo st in terestin g summary o f the divergen t views on the subj ect,with a statemen t of the argumen ts for and against each o f them .

A who le chapter is devo ted to a detailed discussion o f the superficial alteration and secon dary en richmen t o f ore - dep osits, so

impo rtan t from the practical p o in t o f view. Although the gen eralunderly in g prin cip les are well understood

,certain po in ts are still

in n eed of explan atio n ; it is still somewhat u n certain whetherchalcocite an d some o ther sulphides are ever truly primary ,

althoughthe balan ce of eviden ce from observatio n suggests that they are .

The who le pro cess of oxidation,

so lution,

and reprecip itationobviously dep ends o n the chemical an d physical condition sprevailin g in the different regio n s o f the groun d - water

,but the

chemical chan ges invo lved are very comp lex an d n ot y et fullyelucidated .

The seco nd an d larger part o f the bo ok co n sists of description s ofactual occurren ces o f min erals of eco n omic value . These are veryclear an d effective , but it is p erhap s admissible to remark that inthis sectio n a certain wan t o f balan ce is shown . Description s are

given o f man y American dep o sits o f little eco n omic value and stillless scien tific in terest

,while the importan t min in g regio n s of o ther

parts o f the world receive scan t atten tion . It may be suggestedwith al l due deferen ce that the obj ect in view would have beenbetter attain ed by treatmen t o f a smaller n umber o f examp les,culled from all parts o f the wo rld an d selected so as to illustrategen eral prin cip les . Thus the studen t o f econ omic geo lo gy , for whomthe bo ok is primarily in tended, would acquire a better sen se o fprop ortion and learn to appreciate more fully the scien tific and

commercial value o f certain highly imp ortan t typ es of min eraldeposit which do n o t occur in North America .

R . H. RASTALL .

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230 Revi ews— Imp er ia l Sources of P otash.

presen t day in the excavated pits , where rabbits and o ther an imalsstumble - in to the p o o ls Of o il and become en gulfed . A pho tographis reproduced o f a jack - rabbit en trapped in this way .

F . H. A . M.

IMPERIAL SOURCES o r POTASH.

(l ) SOURCES OF INDUSTRIAL POTASH IN WESTERN AUSTRALIA .

By E . S. SIMPSON . Geo l . Surv . W.A . Bull . NO . 77, 1919 .

(2) POTASH RECOVERY AT CEMENT PLANTS . By A . W. G.

WILSON . Can ada,Dep t . of Min es, Bull . No . 29 , 1919 . (3) THE

POTASH SALTS OF THE PUNJAB SALT RANGE AND KOHAT and

SUGGESTIONS REGARDING THE ORIGIN AND HISTORY OF THE

ROCK - SALT DEPOSITS OF THE PUNJAB -

AND KOHAT ‘ByMURRAY STUART . Rec . Geo l . Surv . India

,vo l . 1

, p t . 1, 1919 .

THE acute Shortage o f p o tash which made itself felt durin g theWar stimulated a search for n ew sources throughout the

Emp ire, an d in the three publicatio n s cited above the results of someo f the investigation s then begun are n ow made public .

1 . In the Western Australian Bulletin all the p ossible sourcesare fully discussed an d methods o f treatmen t suggested . It isfoun d that although 1mmen se quan tities of wo od ashes are available ,the con ten t o f p o tash is in gen eral so extraordin arily small that theyare useless except as a lo cal fertilizer . Amon g p o tash - bearin gmin erals the state resources o f microclin e

, glaucon ite, jaro site ,an d alun ite are described

,and it is shOwn that,

if n ecessary ,very con siderable supp lies could be obtain ed . It is

almost n eedless to say ,however

,that the inducemen t to develop

such deposits has n ow van ished . A detailed accoun t o f the alun itedep osits of Kan own a is given by T . Blatchford,

and the results o f

an examin ation Of seawe eds ' for p o tash and iodin e made by I . H.

Boas are also .set forth .

2 . Dr. Wilso n has written a valuable summary o f the probl ems,

scien tific an d commercial,asso ciated with the recovery of p o tash

as a by—product in the Can adian Cemen t in dustry . Equipmen t

for p reven tin g the escap e of flue - dust has already been in stalledin n in eteen cemen t p lan ts . an d of these seven teen were erectedwith the deliberate purp o se of recoverin g p o tash . The quan tityof p otassium salts carried out with the flue - dust varies in ordin arypractice from 2 to 7 lb . p er barrel (350 lb . ) of cemen t . AS the cemen tp lan ts average an individual output exceedin g barrels p e r day ,

it is clear that thousands of ton s o f p o tash are saved an nually ,an d

a serious nuisan ce— due to the escap e o f dust— co n siderably abated .

3. A re - examin ation of the In dian p o tash dep o sits was un dertaken by Dr. Stuart durin g the season s 1915—17 . It was foun d

that the p o tash -s alts occur in discon tinuous len ticles and irregularfo liae

,and that n o continuous bed is likely to be discovered in

Rep or ts if; Proceedi n gs— Geo log i sts A ssociati on . 231

the Salt Ran ge . Where the fo liation is o f the n ature o f bandin g ,bands of po tash may p ersist fo r some little distan ce , but even thenthey wi ll probably thicken an d thi n throughout their len gth . Thep ro sp ects o f obtain in g p o tash in the Salt Ran ge are , therefo re , n otpromisin g , and it is n o t likely to be wo rked profitably excep t as a

by-

product of salt - min in g .

”

In Kohat p o tash has been detectedin water dripp in g from a dep osit in o n e locality on ly , and there itis co ndemn ed by its in accessible situation .

While carry in g out his investigatio n of the econ omic value of thep o tash dep osits, Dr . Stuart made a n umber of observation s on thesalin e dep osits as a who le , an d these he has in terpreted and embodiedin a most valuable pap er o n their origin and history. Briefly , i t issuggested that the rock - salt of Kohat an d the Pun jab belon gs toon e great salt formation ,

and that the differen ces in character o f

the salt exp osed from p lace to p lace are due to the successiveexp osur e of differen t zon es . The Kohat salt con tain s calciumsulphate and belon gs to on e o f the lowest zon es . Various tran sitionzon es are represen ted,

un til at Khewra salt which may have belon gedto the kieserite or carn allite—zon e is en coun tered . It is impossibleto make a comp lete an alogy between the Stassfurt sequen ce an d thatof the In dian dep osits, because the latter have been metamorphosed .

The existin g di p and strike o f the salin e ban ds are probably n ot

tho se of stratification ,but represen t a fo liation in a n ew and differen t

direction . The patchin ess an d len ticular form o f the po tash - ban dsreceive an adequate explan atio n

,and the man y puzzlin g phen omen a

of sequen ce and structure are fully accoun ted for if Dr . Stuart’sviews are correct . In the German an dAlsacian dep o sits, when po tashis on ce kn own at an y ho rizon ,

it can be predicted with certain tyover a wide area

,but in In dia n o assertion can be made as to

where a len ticle of p o tash will o ccur, or as to its dimen sion s o r shapewhen lo cated The prosp ects o f obtain in g p o tash from the SaltRan ge are therefo re, un fortun ately ,

far from promisin g .

ARTHUR HOLMES.

REPORTS AND PROCEEDINGS.

GEOLOGISTS’

ASSOCIATION .

February 6, 1920 .

The Presiden t , Mr . J . F . N . Green ,delivered an address en titled

The Geo logical Structure o f the Lake DistrictGen eral disp ositio n .

The Devon ian con certin a - fo ldin g . Man n er in which it affectsvarious ro cks . Cleavage . Passage in the main vo lcan ic area fromzon e o f flow in the east to zon e of fracture in the west, with concomitan t disapp earan ce o f fo lds an d developmen t o f thrusts . Con

tin uation of the Devoke Water thrusts . The an ticlin o rium .

232 Rep orts (9 Pr oceedi n gs - 4—Geo log i sts’

A ssociati on .

Ordovician fo ldin g . Simple character . Its. imp ortan ce an d mamlin es .

“In terferen ce of the two systems .

Po st- Carbon iferous movemen ts . The Wastwater fault . Co n

sideration o f the effects .o f faults'

in highly fo lded strata . Questio no f tear- faults

March 5, 1920 .

- The Presiden t,Mr . W.

I

Whitaker,

in_

the chair .

The Geo logy '

o f the Cardiff District, _with sp ecial referen ce. to

the Easter ExCui si-on . By Professor A . Hubert Cox , M.Sc .,Ph .D . ,

F.G.S.

Geo lo gical histo ry o f the district . The gen eral succession and

structure . Con tinued in stability an d proximity'

to shore - Ii

Effects thereof on the character an d distribution Of the Palaeo zo icdep o sits . The Armo rican fo ldin g . The Co alfield Syn clin e an d theCardiff An ticlin e . The pre Triassic surface . The Meso zo ic un con

formity an d overlap . Great lateral variatio n Of the Meso zo ic ro cks .

The drain age system an d recen t dep o sits . Main scen ic features .

f ‘

Supp lemen tary No tes on Sho oters Hill . ” By A . L . Leach,

I .

— A section in “

Lon do n Clay .

II . —The Min erals o f the Sho o ters Hill Gravel . Results of an

examin ation by Mr . G. Macdo n ald Davies,M.Sc .

,F.G.S

March 26,1920 .

— The Presiden t,Mr . W . Whitaker, in the

The Geography a‘

n d GeOlogy o f N .E . Fran ce an d adj o in in gareas, with sp ecial referen ce to . theWar Zon e of theWestern Fron t .By Ev .an W Small

,F. .G S.

Gen eral features Of the structural geography of Fran ce . Themassif cen tral an d its historical influen ces : the region s o f theLangue d’

oc an d the Lan gue d’

o il . The pro—Permian Armo rican an d

Variscan highlan ds . The y oun g fo lded moun tain s of the Alps an d

Pyren ees . The belted relief ofN E . Fran ce . The Co tswo ld—Lan gressyn clin e . Relation of structure an d form in up lan d belts . Thecon cen tric scarps as n atural defen ces . The geo lo gy o f the V0an d the Faucilles Moun tain s . The fo lded Jura. an d the tabJura . The Oligo cen e trough valley of the Rhin e . The easternfron tiers o f Fran ce in 1812 an d 1914 . The chain o f fo rtresses . The

min eral resources of Alsace Lo .rrain e The Sarre coal field . TheArden n es an d beyon d . The go rges o f the

I

Meuse an d Mo selle . Thep orphyro i

I

ds o f the Mouse Valley . Some examp les o f river capture .The Eocen e lowlan ds o f Flan ders . The Chalk up lan ds o fNorman dy ,

Picardy , and Arto i-s . The Jurassic in liers o f the 'B-

oulon n ais and the

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234 Rep orts cit Proceedi n gs— Mi n n a log ica l Society .

MINERALOGICAL SOCIETY .

March 16, 1920 .

— S ir William P . Beale,Bart Presiden t

,in the

chair .

Arthur Russell : On the o ccurren ce o f Co tun n ite,An glesite ,

Leadhillite,and Galen a o n

' fused lead from the wreck of the Fireship Firebrancl , Falmouth Harbour

,Co rnwall . ” “The sp ecimen s

were obtain ed in 1846 from the wreck o f the fireship Firebrand,which was burn t in Falmouth Harbour about the y ear 1780 . Theywere foun d un der the lead pump ,

mo st o f which app eared to havebeen melted an d mixed with charco al

,an d con sist of slag - like

masses o f lead,which has eviden tly been fused ,

an d up o n the surfaceand in terstices o f which are n umerous well - defin ed and brillian tcrystals o f co tun n ite an d an glesite , an d more rarely small crystalso f leadhillite an d galen a The co tun n ite crystals , which are co lourless and tran sparen t with brillian t faces, are n early always elon gatedin the directio n o f the Cl axis , an d attain a len gth of 3 mm . Thehabit is somewhat variable owin g to the very un equal deve lopmen to f the faces . The forms observed were 010 , 001 , 021 , 01 1 , 012 , 101 ,111 , and 1 12 . The an glesite crystals are o f rectan gular habit, an dexhibit the forms 100

,001 , 110 , 102 , 122, and 1 13. The leadhillite

crystals, thin six - sided p lates in shap e , are o f a brown co lour and

Show the forms 101 , 201 , 101 , 201 , 112, 111 , 1 12, an d 111 . Thegalen a o ccurs in minute cubo - o ctahedra . An o ccurren ce o f co tun n iteformed un der almost exactly similar con ditio n s has been described byA . Lacro ix . Similar o ccurren ces of lead oxychlo rides at Laurium,

and o f leadhillite in Roman slags from theMen dipHills were referredto .

—W. Campbell Smith Riebeckite - rhyo lite from NorthKordo fan

, Sudan . A rock found by Dr . C. G . Seligman at thebase o f Jebel Katul , 350 miles south - west o f the Bayuda vo lcan icfield was described .

—Dr . G . T . Prio r : The Meteoric Iro n o f

Mt . Ay liff Griqualan d East, South Africa . This meteoric iron ,

found about 1907 . is a coarse o ctahedrite similar in character toWichita Coun ty (Brazo s River) an d Magura (Arva) . On p o lishedand etched surfaces it shows n odules o f graphite an d trio lite , andabun dan t cohen ite crystals arran ged parallel to the o ctahedralbands . It con tain s about 7 p er cen t o f n ickel .

CORRESPONDENCE.

GAULT AND LOWER GREENSAND NEAR LEIGHTON BUZZARD .

S1R,

—I kn ow that my co lleague , Dr . Kitchin,has always foun d

it difficult to believe that the fo ssiliferous limeston e ben eath theGault at Shen ley Hill can be in its o rigin al p o sition ,

an d it is wellthat he an d Mr . Prin gle should have undertaken an in dep en den tin vestigatio n o f the section s . But I am certain that they havemisin terpreted the eviden ce in suppo sin g that the limeston e has been

Gorr esp on olen ce—G. W. Lamp lugh. 2 35

brought below the Gault by Glacial overturn . This is the o n ly p o in twhich it con cern s me to discuss at presen t as the o ther issues raisedin their recen t pap er in y our pages all dep en d up o n it .With a much wider kn owledge o f the section s than I p o ssessed in

1903, when the fi rst accoun t o f the fossiliferous ban d was publishedby the late J . F . Walker an d myself (Quart . Journ . Geo l . So c . ,

vo l . lix, pp . 234 I shall main tain that the descrip tion of thesequen ce and con dition s then given was substan tial lyaccurate . Eversin ce that time I have taken the n eighbourhood of Leighto n Buzzardas my _ geo logical p layground,

revisitin g the section s again an d again ,

Often several times a y ear an d rarely missin gI

a y ear, attracted bythe fresh features disclo sed in the exten sion o f the great san d -

p itsand in n ew excavatio n s . Hen ce

,I have n ow seen the fo ssiliferous

ban d at o n e time o r an o ther in a practically con tinuous sectio n over300 yards in len gth and to 50 yards in breadth , f rom Garside

’

s

p it o n the south to Chan ce’s pit o n the n orth . Yet I have n o t foun din it the slightest trace o f in tercalated Glacial material or o f Glacialdisturban ce . Moreover

, havin g made a particular study o f glaciallytran sp ortedmasses in Yorkshire an d o ther p laces , I am the less likelyto have missed such eviden ce if it had been presen t . Also ,

o n

referen ce to my n o tebo ok,I find that in April , 19 14 , I saw patches

~_of pale - p ink .gritty fossiliferous limeston e , somewhat decomp o sed,

asso ciated with the breccia - ban d at the base o f the Gault in theMiletre e Farm p it (see Fig . 3 o fmy critics ’ pap er) , which lies outsidethe area o f the supp o sed overturn ; an d similar material was latelyvisible in the same p o sitio n in an o ther se c-tio n between this pit an dShen ley Hill .All the n ew features observed sin ce 1903have help ed to co n firm my

o rigin al view o f the sequen ce . Between 1904 an d 1906 the easterlyworkin gs of the Garside ’s p it, n ow aban don ed,

disclo sed n ew factswhich are abso lutely irrecon cilable with the hyp o thesis o f Glacialin version . I men tion -cd some o f these , in brief, in my rep ort o n thevisit of the Geo lo gists’ Asso ciation to Shen ley Hill in 1908 (Proc .

Geo l . Asso c .,vo l . xx

, p t . vi, p . an d dealt similarly

-with theGrovebury sections (with which we are no t at presen t co n ce rned)in rep ortin g on a later excursion to Leighton Buzzard in 1915

(Pro c . Geo l . Asso c .,vo l . xxvi

, pt .

_

v, p . an d as Dr . Kitchin

kn ows, I have embodied a further descrip tion o f them in a pap erwritten just before the War and in ten ded fo r publication at a

con ven ien t season . This pap er will afford me an o pp ortun ity to

deal in detail with the argumen ts o f my critics . Meanwhile , it seems

advisable that I should state at o n ce my disagreemen t with theirmain con clusion

,an d Show reaso n fo r believin g it to be wro n g .

Last y ear it chan ced that I could n ot co n ven ien tly visit thesection s

,though I should have con trived to do so if I had been aware

that my co lleagues’ in vestigatio n was then in progress . However,I have re - examin ed the p its twice durin g the past mo n th , an d am

satisfied that the features with regard to the fo ssiliferous ban d have

236 Corr esp on den ce— G. W. Lamp lugh.

remain ed without essen tial chan ge , and that my critics and I arediscussin g the same facts in this particular .

Dr . Kitchin and Mr . Prin gle rely for pro of Of the in versi on almo sten tirely up o n in feren ces drawn directly o r in directly from thefo ssils o f the limeston es and its asso ciated strata . They in fer thatthe fossils in question— certain brachiop ods , lamellibran chs ,crustacea ,

, an d echi-n oderm'

s— can n o t o ccur in p lace below the Gault .But if the stratigraphical eviden ce is con vin cin g as I believe itis

,that at this lo cality they do o ccur below the Gault

,the a p riori

in feren ce loses all validity . I presume that n o geo lo gist will claimthat our present kn owledge o f the ran ge o f these particular fo ssilsis. so p erfect that it can n o t be exten ded . In strata so sparin glyand sp o radically fo ssiliferous as the upp er part Of the Lower Greensand,we kn ow as y et very little about the life of the p eriod . Now,

the Shen ley section,as I believe , has Slightly exten ded our kn ow

ledge and,in tli e

I

pap er'

of 1903,my co - author an d myself Offered

what I still ho ld to be a reaso n able exp lan ation o f the unusualelemen ts o f the faun a . Our critics .naturally lay stress up o n theirown side of the argumen t , an d dismiss the admixture o f LowerCretaceous forms as derivatives ’

an d as o ccurrin g , p erhap s, ina limeston e similar to the so~called Cen oman ian ro ck , but of

differen t age , an d brought in to con tact with it by the inversio n .

I hardly n eed express dissen t from these in feren ces ; t hey mergein to the bro ader question o f the

I

supp o sed Glacial overturn . Let us

co n sider what this hypo thesis implies , an d howfar it run s con traryto probability .

1 . The supp o sed Cen oman ian limeston e,

a gritty ro ck o f

p eculiar asp ect an d comp ositio n (fully describedI

in our pap er o f

is un like an y o ther ro ck kn own in the district , an d shows everyin dication o f havin g been formed o n the flo o r o n “which it n ow rests .

My“

critics have sought fo r it above the Gault all alo n g the fo o t o fthe Chalk escarpmen t , and ackn owledge that they have soughtvain . They fall back up on an assumptio n that it may have o ccurredabove the Gault m a van ished tract in the n eighbourhood o f Shen leyHill , an d that it may have remain ed at the surface there un til thehyp o thetical in versio n , in Glacial times . Yet it is o n ly a few in chesthick

,an d is fo r the mo st part quite fresh an d unweathered .

2 . In the same way the bed o f lo o se glauco n itic green san d,up to

ick,which I saw below the Gault, surroun din g an upstandin g

crag o f iron grit , in the“ easterly part o f Garside’s p itI

befo re thewo rkin g was abandon ed in 1906 (se e Proc . Geo l . Assoc .

,vo l . xx ,

p . is supp osed to have been overturn ed from the surface ;y et it also , though so -readily p erishable , shows n o trace Ofweatherin g .

13. The slab o f Gault , g reen san d,an d

'

limesto n e suppo sed to _havebee n overturn ed has proved to exten d without“ visible disturban ceover an area o f n ot less than 15 acres

,an d it. still has a thick n ess o f

about 18 feet in Harris ’s pit, which , therefore , must be accep tedas the min imum for “the who le slab before the overturn . Not a trace

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Gorresp on olen ce— N. L. Rowen .

CRYSTALLIZATION—DIFFERENTIATION.

SIR,

—Mr . H. H. Read’

s acquain tan ce with modern Fren chliterature is eviden tly thorough , and o n e is surprised that thisacquain tan ce has n o t rendered himmore apt at simile . He comparesmy depen den ce up on crystallization as an exp lan atio n o f man yfeatures o f ign eous rocks with M. d

’

Astarac’

s dep en den ce up on

sy lphs as an exp lan ation of o rdin ary happen in gs . Un fortun atelyfor his compariso n , we kn ow that magmas do crystallize , and

equally un fo rtun ately fo r his dep en den ce up on liquid immiscibilitywe do n o t kn ow that silicates unmix . Immiscibility is the p etro logicsy lph .

In fact , immiscibility is a so rt of sup er - sy lph . On e sees tworelated an d in timately associated ro cks

,an d o n e remarks that they

were eviden tly formed from a common magma by unmixin g . Sin cen othin g is kn own about unmixin g in silicates

,o n e is therefore

relieved from the resp on sibility o f an y further thought in the matter .

However . Mr . Read’

s last p aragraph rouses some hop e . He exp ectsthat my excessive advo cacy o f crystallization will lead some o n e tochamp io n immiscibility . If this some o n e will an alyse immiscibilityfrom a theoretical standp o in t , if he will then app ly his results tosilicate magmas and examin e whether associated ign eous ro cks

bear such a relation ship to each o ther in chem1cal comp ositio n ,in

time an d Space relation s, that they can or can n ot be regarded as theresult of immiscibility ,

he will have con ferred a bo on uponp etro logists, whether a succeedin g gen eration shall fin d '

his con

elusion s right or wron g . But n o amoun t of settin g up immiscibilityas a sy lph will advan ce p etro logy .

It is p o ssible, o f course , that I have overworked crystallizationbut n o on e who has seen the Sprin g break—up in on e o f our Can adianlakes could doubt that deformation o f a crystal mesh must haveimp ortan t con sequen ces in the case of ign eous ro cks as well . Thereon e sees .weaken ed an d hon ey combed bodies o f ice un der impactfrom o ther masses , locally compacted in to a so lid mass with thewater squeezed out o f the comb , elsewhere stretched,

fissured,and

traversed by streaks o f o p en water . That mo re Or less relatedfeatures could develo p below groun d is n ot to be questio n ed .

ThoughMr . Read’

s review is for the ni o st part a series of obj ection sthey are n early always gen eralities , an d are on ly o ccasio n allysp ecific en ough to be an swerable . My method o f derivin g some 1

banded ro cks by torsion o f a crystal mesh would n ot, as he co n cludes,give rise to an orien tatio n o f the early crystals n o rmal to the ban ds .

It is in the fillin g o f the len ticular spaces that free flow Of' liquid

o ccurs and such cry stals as would become detached from the wallso f the len s during this actio n would be carried alon g bv the liquid

1 I have e lsewhere sugge sted that ban ded ro cks may at time s be formed as

a result o f in trusion o f heteroge n e ous l iquid (n ot immiscible l iquids ) . “Later

Stage s o f the Evo lution o f the Ign e ous Rocks ” Journ . Geo l . , Supp l : to

vo l . xxii i , 1 9 15 , p . 30 .

Obituary— Rober tEther idg e . 239

and orien ted parallel to the ban din g . The Slight amoun t of ro tatio no f crystals p ossible in the compacted part of the mesh would n ot besufficien t to o rien t them in an y particular way . The action would,

as a who le , give rise to ban ds showin g flow—structure, therefore ,and exhibitin g the moderate co n trast between bands that is n o rmalin banded gabbro . The occasio n al ultra - basic ban ds of extremecon trast could also be develop ed as a further result , fo r in thelarger len ses o f liquid crystal so rtin g would o ccur under conditio n sparticularly favourable to the p roductio n o f mon omin eralic typ es .

Though apparen tly n o t himself a stro n g advocate o f crystallizationdifferen tiatio n ,

Mr . Read appears to have some apprehen sion thatthe credit for origin atin g certain ideas in that con n exion might leakout o f the Tight Little Island . He therefore p o in ts out that Darwinp ostulated crystal - settlin g seven ty y ears ago , an d in two p lacesthat Barrow p ostulated mechan ical strainin g thirty y ears ago .

Though Darwin n eeds n o eulogy o f min e o r Mr . Read’

s, I to o havep o in ted out Darwin ’

s o rigin atio n o f the idea o f crystal - settlin g ,1and tho ugh I have n o t referred directly to Barrow 3 wo rk . I havereferred to Harker’s discussio n o f it an d similar work .

2 If I may bepermitted

,I would l ike to p o in t out to

,Mr . Read that the

assumptio n o f immiscibility also dates back to Darwin ’

s time,

and that it is still an assumptio n— a sy lph , if he prefers the term .

N. L . BOWEN .

KINGSTON , CANADA .

February 2 7 , 1 920 .

OBITUARY .

Ro be rt Ethe ridge (1847

MR . ROBERT ETHERIDGE,the so n o f the distin guished geo logist and

palaeo n to logist o f that n ame , died after a short attack o f pn eumo n iaat Co lo Vale

,near Sydn ey , on Jan uary 4 , in his 74th y ear . Etheridge

early to ok up geo logical wo rk in Australia , as a member of the firstGeo lo gical Survey o fVictoria,

un der the direction o fA . R . C. Selwyn ,

in the middle sixties . The survey havin g been disban ded as theresult o f a p o litical crisis , y oun g Etheridge return ed home an d was

app o in ted palaeo n to logist to the Geo logical Survey o f Sco tlan d,his

father bein g then palaeon to lo gist to the En glish Survey . When then atural history co llection s o f the n ation were removed from

Blo omsbury to the n ew Natural History Museum in the CromwellRoad

,the two Etheridges were brought o n to the staff Of the

Geo logical Departmen t , where the memory still remain s of thevigorous actio n s an d lan guage o f R . E . jun io r The chief p ieceof palaeon to logical work accomp lished by Etheridge while in this

1 N. L . Bowe n , Crystal l ization Differen tiation in Sil icate LiquidsAm . Journ . Sci . , vo l . xxxix , 1 915 , p . 175 .

2 “Late r Stag e s o f the Evo lutio n o f the Ign e ous Rocks Journ . Geo l . ,

Supp l . to vo l . xxi i i , 1 9 15 , p . 14 .

240 Obituary RobertEther idg e.

position was the valuable Catalogue o f the Blasto idea, in which hehad the co - op eratio n o f P Herbert Carp en ter .

Australia, however, was never far from the thoughts of Etheridge .He comp iled a useful biblio graphy o f Australian Geo logy , an d

studied fossils sen t to him from Queen slan d by his fo rmer Edin burghco lleague , Mr. R Logan Jack . This even tually resulted in a largewo rk by the two friends o n The Geo logy and Palaeon to logy of Queen sland andNewGa in ea Meanwhile , in 1887, Etheridge return edto Australia as p alaeon to logist to the Geo logical Survey o fNew SouthWales an d to the Australian Museum

,Sydn ey . Here he stren uously

“

worked for the remain in g thirty - three y ears o f his life,becomin g

Directo r o f the Museum in 1895 . At the Min es Departmen t he laidthe foun dation o f what is n ow a fin e library ,

he started the wellkn own Records o f the Geo logical Survey and he published fromtime to time important memo irs o n the fo ssils o f the o lder rocks .

Produced without the facilities - enj oy ed by p alaeon to logists at home ,these writin gs were warmly welcomed by them ,

an d“ it is n ot to o

much to say”

,writes Pro fessor Edgewo rth David,

“t hat the

classification an d correlation o f the coalfie lds, go ldfie lds , artesianwater - basin s

,o ilfie lds

,an d o ther min eral dep o sits o f the Common

wealth are based essen tially -

o n the wo rk o f Mr . Etheridge . ” At

the Australian Museum Etheridge threw himself with his won tedvigour in to the arran gemen t an d disp lay o f the co llection s

,and

in troduced the descrip tive labellin g in itiated i n the Natural HistoryDepartmen ts o f the British Museum . He founded the Records o f

the Australian Museum ”

,an d un der his guidan ce n umerousmemo irs

on the faun a of the co n tin en t were published . He also extendedthe educatio n al services of the museum by p opular scien ce lecturesand demon stratio n s to visitors . In this po sitio n he was led, as so

man y o thers, away from his own scien ce to fo llow the in sisten tcall of ethn o logy . Through his effo rts a fin e series o f ethn o logicalexhibits from the Pacific Islands was accumulated,

an d a

magn ificen t disp lay o f n ative wo rk was in stalled in the museumgalleriesEtheridge received the Clarke Memo rial Medal from the Royal

So ciety o f New South Wales in 1895,an d the Mueller Memorial

Medal from the Australian Asso ciatio n fo r the Advan cemen t of

Scien ce in 1911 . His remo ten ess from the Mo ther Coun try and his

obj ection to advertisemen t were p robably the reaso n s why similarho n ours were n ot co n ferred up on him by Metrop o litan so cieties .

The award o f the Wo llaston Fun d by the Coun cil o f the Geo logicalSociety in 1877 is all that we can trace . His n ame , however, is Widelykn own

,n o t from the various fossils that have been n amed after him ,

but from the An tarctic glacier, the lo fty p eak on the Ko s’ciuskoPlateau

,an d the Etheridge go ldfie ld in No rth Queen sland . His

co lleagues will cherish his memory as that o f a sound an d un tirin gworker

,an d a man alway s ready to help his fellows .

1 Se e additio n al paragraph on p . 194; writte n by Mr. R . Bul len Newton .

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242 Edi tor i a l Notes .

o n our space it is n ot p o ssible at the momen t to give an adequateaccoun t o f his distin guished career, but we i n ten d to do so at an

early date . It must suffice here to say that he has accomplished an

en o rmous amoun t of sterlin g wo rk, a full bibliography o f his

publication s, in cludin g j o in t work , run n in g to n o less than n in etyfive items

,an d coverin g investigation s i n the palaeon to logy o f almo st

all region s of the world where fo ssils are foun d . Mr . Bullen Newtonhas

_

also o ccup ied the p o sition s of Presiden t o f the Malaco logicalSo ciety of Lon don (1910 and of the Co n cho logical So ciety o f

Great Britain and Irelan d (1913 an d his sp ecial in terests havealways lain in the direction o f the Tertiary an d youn ger formation s .

WE have received a copy o f the ThirdAn nual Rep ort of the Con j o in tBoard of Scien tific So cieties

,coverin g i ts activities for the

y ear 1919 , Several of the Committees deal with matters p ossessin ggeo logical in terest, such as tho se on Iron - ores and theWater Powero f the Empire . A Commi ttee fo rmed j o in tly by this Board and theBritish Asso ciation has en tered in to n ego tiation s with the Un iversityo f Cambridge and the Imp erial Co llege as to the p o ssibility of

o btain in g fun ds for the establishmen t of a Geophysical In stitute .The mo st in terestin g rep ort, however, is that of the PetrophysicalIn stitute Committee

,o f which Sir Jethro Teall is chairman an d

Professor Fearn sides secretary . A full rep ort has been drawn up on

the n eed for a n ation al in stitute to investigate the condition s of

cry stallization o f min erals an d ‘

ro cks,and advice has been obtain ed

from the Geophysical I n stitute an d the Carn egie In stitution at

Washin gton . The Committee is n ow prepared to approach theDepartmen t o f Scientific and Industrial Research with a view to theo rgan ization o f a Petrophy sical In stitute .

>i<

THE twelfth an nual rep ort o f the govern in g body o f the Imperl alCo llege o f Scien ce an d Techn o logy con tain s much matter o f in terest,esp ecially a full accoun t o f the wo rk o f the Departmen t of Geo logy ,in cludin g Min in g Geo lo gy an d Oil Techn o logy , an d of the Departmen t of Min in g . As is the case everywhere at presen t there wasmuch overcrowdin g , an d some in tendin g studen ts in Min in g Geo logyhad to be excluded owin g to lack of equipmen t . It is impossiblein the space at our dispo sal to men tion even a small part o f theimp ortan t wo rk of teachin g and research which IS bein g carried on

at this great co llege ; its activities cover almo st every po ssible fieldo f learn in g an d techn o logy to which geo logy can be applied, and wecan o n ly co n gratulate Professor Watts

,Pro fessor Cullis, an d their

staff o n the brillian t results attain ed . It is p leasin g to observethat a large prop ortio n o f the origin al pap ers published durin gthe y ear by members o f the various bran ches o f the Departmen t ofGeo logy app eared In the pages o f the GEOLOGICAL MAGAZINE .

The Re p o rt o f the No n -Fe rro us Min in g Comm itte e

DURING the last few mo n ths we have frequen tly referred in our

Editorial No tes to the pro ceedin gs of the Board o f TradeCommittee on the Non - ferrousMin in g Industry . This committeewhich was comp o sed as fo llows Mr . H. B . Betterton ,

M.P . (chairman ), Mr . H. F . Co llin s, Mr . J . Harris, Dr . F . H. Hatch

,Mr . R . A .

Thomas,Mr . J . Wign all, M.P. ,

and Sir Lio n el Phillip s, who wasobliged to resign very so on after app o in tmen t— has n ow with c‘

om

mendable promp titude.

issued its rep ort, a do cumen t o fmuch in terestfrom man y po in ts of vi ew . While n ot primarily con cern ed with thegeo logical asp ects o f British n on f- erron s min i n g , the Committeehave n evertheless investigated with some thoroughn ess certaingeo lo gical matters in co n n exion with the tin lodes of Cornwall,the lead - zin c depo sits o f n orthern En glan d, Scotland, an d Wales

,

and the bary tes of Shropshire . A mo st in terestin g extract is givenfroma rep ort by Dr . Malco lm Maclaren to Messrs . Bewick

,More in g

and CO . , on the cen tral min es o f the Camborn e - Redruth area,

summarizin g his views o n the limits in dep th of profitable tinworkin g in that district . Dr . Maclaren p o in ts out that in mostin stan ces there is a marked fallin g o ff in tin —con ten t at an averagedepth below the gran ite - killas con tact of about 200 fathoms

,or

'

some360 fathoms from the surface ; o n ly in o n e case

,the well - kn own

Do lcoath ore - body ,did productive o re exten d much below this ;

even this has failed at about the 500 fathom level . The facts he’resummarized are en tirely co n sisten t with the views as to the existen ceof d efin ite min eral zon es brought forward in the recen t paper byDr. W. R . Jon es at the In stitution o f Min in g an d Metallurgy ,

an d

in the discussion o n that paper by Professor Cullis, Mr . Bastall ,Dr . Hatch

,an d o ther sp eakers . Favourable referen ce is also made

to the pro j ects for exploration below the abandon ed shallow ‘min esof this district by mean s o f cross - cuts driven from the workin gs '

o f

the larger an d deep er min es . It is certain that the gran ite - killasco n tact must exten d far to the n orth of its surface outcrop at n o

very great dep th ; there is every probability that this con tact isin p o in t of fact an un dulatin g one , and accoun t must be taken o f thefact that gran ite again comes to the surface at St . Agn es, where alsothere is well - developed min eralizatio n . It seems probable that allthe gran ite bo sses of Cornwall an d Devon are in - po in t of fact lo caldomes

, cupo las in the American sen se o f the term,o n the surface

of a great bathy lith , un derly in g the who le regio n at a rather smalldepth . It is o f course un certain what this actual dep th may be ,and in p laces it is probably below the limit of workin g un der presen tcondition s there is also the further fact to be taken in to accoun tthat in America it is believed that ore - min erals tend to co n cen tratethemselves In the upp er parts o f these cup o las . Hen ce it is n ot safeto in fer the existen ce of a tin z- on e all over the upper surface o f the

244 Rep ort of the Nc it - Ferr ou s Mi n i n g Comm i ttee .

bathy lith . Nevertheless the widespread o ccurren ce in the shallowermin es o f copp er lodes is an en couragin g feature fro‘

m this p o in t o fview,

suggestin g the existen ce below them of the tin ,wo lfram

,an d

arsen ic zon es . Several witn esses befo re the Committee asked forfin an cial assistan ce from the Governmen t to assist exp loration s o f

hitherto undevelop ed deep - level areas,an d it may be said that

geo lo gical theo ry , so far as it go es, is favourable to the prosp ects -o f

a successful issue .Co n siderable space is devo ted to a description of the pro j ects

for the drain age to lower levels of the Halkyn—Llan armo n area inFlin tshire

,which is co n sidered to be perhap s the mo st imp ortan t

area o f lead an d zin c ores in the who le coun try . Here the prob lemis main ly geo logical , and dep ends Who lly on the well - kn own watercarry in g capacity of the Carbo n iferous Limeston e an d the co n

sequen t p eculiar behavio ur o f the river system of that district . Herethe geo logy is p erfectly simp le , an d the who le question is n ow main lyfin an cial ; if the pro j ect for the con tin uan ce of a n ew sea - leveldrainage tun n el (which has been already started) can be carried out,

some extraordin arily rich and productive vei n s can be worked downto a much lower level than at presen t, an d a large additio n made tothe home supp ly of lead an d zin c fo r man y y ears to come . Thisseems to be pre - emin en tly a case for Governmen t assistan ce . Thecase for a similar scheme for the Wan lo ckhead and Leadhillsdistrict app ears to be less con vin cin g, an d n either the compan iescon cern ed n o r the royalty own ers seem to displ ay much en thusiasmo n the subj ect, owin g to the immen se cap ital expenditure n ecessaryfor a 7 mile tun n el in hard Palaeo zo ic ro cks .

An other p o in t o f geo lo gi cal in terest arises in co n n exio n with thelead - zin c dep osits o f Northumberlan d,

Durham,an d adj o in in g

coun ties,which are chiefly in the Great Limeston e , an d are

approachin g exhaustion . Professor Louis suggested in e viden cebefore the Committee that trial should be made o f the MelmerbyScar Limeston e as an o ther p o ssible productive ho

'

rizon . This raisesan in terestin g questio n as to the in fluen ce o f the Whin Sill on ore

dep osition in this n eighbourho od, as to which little in formatio nseems to be available . It is gen erally stated that in Derbyshirelead- zin c o re - bodies are n ot foun d in payable quan tities below thetoadston e, a presumably imp ervious ign eous rock ; this suggestsa downward movemen t o f the min eralizin g so lutio n s . On the o therhan d,

accordin g to accep ted modern theories o f o re dep osition ,

the mo vemen t should be upward an d the o res foun d below the Ign eousro ck . To o n e un acquain ted with lo cal con dition s the question at

o n ce suggests itself whether prop er exp loration s have ever beencarried out below the toadsto n e

,or whether the absen ce o f ore

there is an assumptio n . With regard to the Whin Sill and.

then orthern area the same question i s p ertin en t , as is well kn own ,

the Whin Sill is tran sgressive , o ccurrin g at differen t horizo n s inthe Carbon iferous at differen t p laces, an d it may be suggested that

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ORIGINAL ARTICLES.

A Re ce n t Wo rldw ide Sin kin g o f O c e an - leve l

By REGINALD A . DALY ,Harvard Un iversity , Cambridge,

Massachusetts .

In troduction .

Fie ld Observation s .

First Con tact with the Problem.

Gulf o f St. Lawren ce .

Main e .

Samoa .

Difficulties of an In ductive Study o f Records .

British Isles .

Atlan tic Co astal Plain o f the Un ited State s .

Florida Key s an d West In di es.

South America .

Graham Lan d .

New Zealan d .

Australia .

Pacific Islan ds .

Californ ia .

Amoun t of the Eustatic Chan ge .

Con temp o ran e ity an d Age o f the Stran ds.

Cause o f the Eustatic Chan ge .

Con clusion .

LOCAL uplift and local sinkmg of the earth’s surface have beenfully demon strated for past geo logical epochs . The amoun ts

o f these movemen ts have gen erally been stated with re feren ce tothe presen t sea - level

,an d for the greater movemen ts the statemen ts

of magn itudes are n o t seriously impaired by the fact that gen eralsea - level itself has been shi ftin g, upwards an d downwards, throughgeo logical time . Amon g .

the causes for gen eral o r eustaticshifts of sea - level are : appropriate crustal movemen ts wherebythe vo lume o f the o cean basin has been chan ged ; delta - bui ldin gan d vo lcan ic eruption o n the sea - flo or, the disp lacemen t of sea - watern ot bein g comp en sated by crustal sinkin g ; vo lcan ic addition of

n ew water to the o cean ; subtraction of water which becomeschemically boun d durin g the alteration o f ro cks glaciation on land,lowerin g sea - level by the abstraction of water from the o cean ;deglaciation on lan d

,raisin g sea - level ; chan ges in the earth

’

s

cen tre of gravity and in her speed o f ro tation .

1

Numerous as these possibilities are the pro of o f a eustatic chan gein shore - levels is n ot easy . In the fo llowin g pages are recorded somefield facts which suggest the p robability o f a sinkin g of gen eral sealevel to the exten t o f about 20 feet durin g the human period . The

1 The write r has re ce n tly foun d that A . Ty lo r (GEOL . MAG .,1868, p . 576 ,

an d 1872 , p . 392 ) an ticipated eve n Be lt in re latin g the o rigin of coral re efs

to the shift of o ce an - leve l con sequen t o n deglaciation . W. B . Wright (TheQuatern ary Ice Age , Lon don ,

19 14 , p . 4 17 ) be lieve s the submerged fo rests of

the British Isles p rove a eustatic shift o f 55'

to 60 fe et, if n ot of conside rably

greate r amoun t, an d attribute s it to deglaciation .

Recen t Si n ki n g of Ocean —leve l .

suggestion is published, n o t to express'

a fixed con clusio n,but to

invite criticism by those familiar with sho relin es in differen t partso f the world, for the testin g of the idea is man ifestly a worldwideproble

The matter is importan t because It affects judgmen t as to thereality o fman y so - called up lifts o f lan d o r sea -

,bo ttom and because

a close study o f the latest shift o f sea- level may help _

to systematizethe criteria for earlier an d larger eustatic shifts .

FIELD OBSERVATIONS .

First Contact with the Problem — The hy po thes1s o f . a Recen t,n egative shift o f sea - level first suggested itself to the writer n earlytwen ty y ears ago ,

while en gaged in the correlation o f p ost—Glacialelevated stran ds in Labrador and Newfoun dland with those o f

Quebec . The highest stran d mapp ed between Newfoun dlan d an d

Nachvak Bay ,500 miles to the n orth - west

,was foun d to be stro n gly

warp ed ; its gradien t varies from 1 to 3 feet p er mile , measuredalo n g the coast and thus n o t at right an gles to the isobases . Thehighest stran d in Main e has maximum gradien ts o f 5 o r mo refeet p er mile . Ice attraction fails to accoun t for such high valuesan d even for the lower gradien ts o f the o ld stran ds aroun d the GreatLakes

,where also crustal warp in g is gen erally credited .

_On the

o ther han d, the lowest emerged terrace alo n g the shores o f the Gulfo f St . Lawren ce was seen to be con spicuously

'

leve l throughout adistan ce of 300 miles o r mo re below Quebec City . The apparen tun iformity o f level p romp ted the questio n whether this particularstran d had been abando n ed by the waves because o f a sin kin g o f

gen eral sea -

.level For lack o f accurate levellin g , defin ite co rrelatio nwith the '

mo re clo sely studied,lowest beaches cf Labrador was

imp o ssible , an d withthe data in hand serious belief in the hyp o thesiso f a eustatic chan ge was withheld .

However, that exp lan atio n was recalled by the discovery of n ew

facts durin g recen t field studies o n the sho res of New En glan d,Florida

,an d the Samo an Islan ds . Mean time , Go ldthwait had made

a careful study o f the St . Lawren ce stran d ,to which he gave the

n ame Micmac terrace the results o f his levellin g agree so wellwith tho se made in the o ther regio n s men tio n ed that the suspicio no f past y ears has become a hyp o thesis that seems to deserve mo reatten tive con sideration .

Forthe opp ortun ity to co llect data from the two tropical region sthe writer i s in debted to Dr . A . G Mayor, Directo r o f the Marin eLaborato ry o f the Carn egie In stitutio n o f Washin gto n .

Gulf of St. Lawren ce — In his excellen t accoun t o f the Micmac

terrace, Go ldthwait writes Traces o f wave work alo n g the south

co ast o f the Sain t Lawren ce were found at al l altitudes below theupp er limit o f submergen ce . Con trary - to exp ectation ,

again , therep roved to be n o sho reline below the highest o n e ,with-

_the excep tio n

o f the twen ty - foo t [Micmac] stran d,which p o ssesses en ough

248 Professor R . A . Da ly

in dividuality o f character, en ough stren gth o f expression or en oughco n tin uity to indicate a lon g stand o f the sea at an y level . Distin ctbeach fragmen ts were foun d at all altitudes, in such p laces as werep eculiarly favo rable to expo sure to the op en sea

, or in supp ly o f beachmaterial . This is believed to in dicate that the emergen ce o f the Sain tLawren ce v alley from the Champ lain sea was n ot accomp lished byspasmodic up lifts, separated by in tervals o f rep o se , but was fairlysteady and co n tinuous . In marked con trast with the weak beachesat higher levels , the shorelin e which stands 20 feet above the sea isstron g an d co n tin uous .

” 1 Similarly ,the presen t writer could find n o

sure eviden ce o f pron oun ced halts in the up lift o f Labrador, where ,however“

,the great stren gth o f the bed- rocks and the gen eral absen ce

o f thick glacial drift would in an y case fo rbid the developmen t ofcon tinuous beaches or ben ches in the time available . Fo r the samereason s the top o graphic equivalen t o f the Micmac terrace would n ot

be exp ected in Labrado r, excep t quite locally ,even if the emergen ce

to ok p lace at iden tical rates'

in the two regio n s . The width o f theMicmac terrace varies from a few feet to 1 5 miles or more . Thougho n ly a part o f its width is due to wave cuttin g , an d thoughthe formatio n s affected are relatively weak the 20 ft . higher levelo f the sea must have been steadily kept for a large fractio n o f po stGlacial time .Farther east in the Gulf o f St . Lawren ce , a t An ticosti, Twenhofe l

foun d elevated shorelin es at in tervals up to 350 feet above sea .

The lowest is between eight and fifteen feet above high tide . ”The corresp o n din g terrace reaches a maximum width o fmore thantwo miles an d will average more than o n e - fourth mile On theeastern two - thirds of the south coast for about 80 miles , this terraceis two or mo re miles wide an d is described as o ccurrin g in man yo ther parts o f the island .

At Arisaig , Nova Sco tia,o n Northumberland Strait , Twenho fe l

n o ted a raised ” beach,roughly estimated to be 25 feet above

sea (mean water- levelMain e . Throughout the region _

o f Pen obsco t Bay the bestdefin ed and mo st widely develop ed terrace has an elevatio n of

20 to 25 feet above sea- leve l .” f In the Ro ckland fo lio o f the Un ited

States Geo logical Survey Bastin writes (1908) The mo st widelydeveloped terrace stan ds about

'

15 to 25 feet above mean tide .Alon g the Main e coast in gen eral Ston e n o ted eviden ce o f. a pausein the post—Glacial “ fall o f the sea ”

at an elevatio n o f 20 feetabove (mean sea - level . 5 The presen t 'writer’s field observation saccord with these published statemen ts

,which indicate a recen t,

1 J . W. Go ldthwait, Ame r. Journ . Sci . vo l . xxx1i , 19 1 1 , pp . 293- 4 .

2 W. H. Twe n ho fe l , Amer . Journ . Sci vo l . xxx , 19 10, pp . 66 , 69 .

3 Ibid . , vo l . xxvi ii , 1909 , p . 147 .

4 G. O . Smith , E . S. Bastin ,an d C. W. Brown , Pen obscot Bay fo lio ,

U .S

Ge o l . Surve y ,1907 p . 13.

5 G. H. Ston e,Mon ograph 34, U S. Ge o l . Surv . ,

1899, p . 53.

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250 Professor R. A . Daty

amoun t, but also by the state o f preservation of the strand marks .

Allowin g for litho logical differen ces, cliffs,

-

,ben ches caves

,an d

chasms have comparable stren gth o f deVe lopriIen t In the two regio n s,in each o f which the sea must have wo rked a relatively lo n g timeat the 20 ft. level . Sin ce the shift of level the surf has destroy eda part (if each ben ch In Samoa

,therewith do in g wo rk roughly equal

to the destructive wave - work already p erformed o n equally hardro cks in Main e .Difiiculties of an In ductive Study of Record. .

-The hyp o thesiso f a eustatic chan ge must meet the obvious test o f matchin g thefacts observable o n the shores o f every con tin en t an d n early all

islands . That the app lication o f the test is n ot easy will be clearfrom the fo llowin g con sideration s .

1 . Mo st shores have n ot been studied with requisite tho roughn ess .

The comp ilation o f the published, appropriate records, in completeas they are

,is a herculean job . Apart from the time an d phy sical

labour invo lved,the compiler is baffl ed by the psy cho logy of

'

ma'

n yauthors, who have observed in the field an d then written theirrecords un der. the more or less un con scious con tro l o f the up lifthyp o thesis . Relevan t an d p erfectly accessible facts have therefo ren o t been n oted . Moreover

,the selection o f data in statistical study

has its own obvious dan ger for the comp iler .

2 . Writers have n o t alway s been care ful to give the datum from

which the level o f each raised stran d was measured . In gen eralsea - level is men tion ed without sp ecify in g—mean level or hightide level or an y o ther un equivocal datum . The omission is seriousfor the comp iler dealin g with a shift of o n ly feet .3. The marks o f a

“ higher stan d of sea - level depend for theirclearn ess on several highly variable factors, in cludin g : the stren gthan d o ther characters o f the shore ro cks the expo sure o f the coastas it affects the fetch an d p ower o f the waves ; the p ower o f tidalcurren ts ; the p osition o f wave - base at the o ld shore , especially thedepth o f the ro ck - ben ch cut by the waves

'

at the fo ot o f a recedin gsea cliff ; the degree to which the records o f the higher stand o f thes ea have been destroy ed by the waves actin g at presen t sea -

.levelThe in fluen ce o f ro ck variation is well illustrated In New En glan d,

where glacial deposits were distin ctly cliffed at the 20 ft. level ,while the massive gran ites suffered little ben chin g . As alreadystated, the con trast between the shores of the St . Lawren ce and thoseo f Labrador in this resp ect is very striking . Even where the shorematerials were quite in coheren t

,as alon g y oun g coastal plain sh

sea cliffin g might n ot have taken place systematically at all . Moderne xamp les show progradin g , rather than retro gression ,

o f the shorelin e . Thus the sea - cliffs of the 20 ft. stran d would vary in height

'

from zero upwards .

The crest o f a storm beach is n o t sea - level . The more p owerfulthe waves the greater is the differen ce of these two levels .

‘ Frompublished texts on e can n ot always be sure that due allowan ce

Recen t Si n ki n g of Ocean - ten et. 25 1

has been made for the differen ce in estimatin g fo rmer sea—levelfrom emerged beaches .

Variation in the p o sition o f wave - ba se is worthy of sp ecialatten tion . Waves run n in g in on a flat shal low shelf are damp ed,

so that wave - base approaches a min imum dep th in sho re . Wavebase i s deep er alon g a steep - to shore , o ther thin gs bein g equal . In

the former case the fo o t o f the se a - cliff is characteristically at o r

n ear high - tide level ; in the latter case it i s typ ically well belowhigh - tide level , as exemp lified in Samoa,where man y headlan d cliffsp lun ge in to water about 2 fathoms deep . Gen erally o ld stran d - levelso n o cean ic islan ds are likely to be n o tably higher than thecorresp o ndin g wave - cut ben ches , as well as -2' to 10 o r more feetl ower than the level crests of storm beaches .

4 . Wherever a coastal region is n ow un dergo in g , o r has recen tlyun dergo n e , a crustal movemen t

,the search fo r lo cal eviden ces o f

an earlier eustatic sin kin g of o cean level may give n egative or

doubtful results . The marks o f the o ld stran d may be drown ed,

o r else elevated to heights which are n ot to be directly co rrelatedwith the heights o f the o ld stran d In undisturbed ro cks .

5 . In sp ecial cases the eustatic shift may . lo cally cause a chan geIn the tidal ran ge, affectin g the datum if this be high tide .6 . Fin ally the height o f the o ld stran d lin e above mean sea

- levelmay dep end on the cause o f the eustatic shift . Supp o se , fo re xamp le , that. a shift of level averagin g 20 feet were d ue to a recen tin crease of the ice—cap on the An tarctic co n tin en t . Near the ice - capsea - level would be kep t, through gravitative attractio n by the n ewice

,a little higher than it would be if abstraction o f water from the

o cean were the o n ly cause for the chang e o f level . In the n o rthernhemisphere the lowerin g o f sea—level would be a ll the greater becauseo f attraction to the n ew ice .

For man y reason s,therefo re

,the search for comp lete p ro of of

the eustatic shift here p o stulated is boun d to be pro lon ged . Meantime a prelimin ary study o f some records made in separate mutuallyd istan t regio n s has been made

,with results that also show the

hyp othesis'

to merit discussion an d further testin g: Certainexamp les may n ow be briefly reviewed .

British Isles .

- The raised beaches o f Sco tlan d and Irelan d are

c elebrated,and like the American cases already n o ted,

o ccur in

an area o f up lift fo llowin g deglaciation . In Sco tlan d the up lift wasdifferen tial

, but accordin g to mo st published statemen ts the lowestbeach is at n early con stan t level , which is sometimes described as

about 20 feet or about 25 feet above Ordn an ce datum . Ordn an cedatum i s mean water level at Liverp o o l , so that the beach variesfrom 15 to 20 feet above lo cal high tide , accordin g to these statem en ts. Geikie writes : The mo st promin en t o f all the raisedbeaches is that which lies at a height of about 20 or25 feet abovehigh water . vary in g in readth from 6 or 7 miles to n otmore thana few feet . Alon g its in n er edge are sea - cliffs

,caves

,sea - stacks,

252 Pr ofessor R. A .

'

Da ly

an d skerries . This beach must be more or less familiar to every on ewho has visited almo st an y part o f the coast - lin e of Sco tlan d .

” 1

Man y memo irs o f the Geo logical Survey -

of Sco tlan d bear referen cesto this beach

,which is described as seen at frequen t in tervals

o r

'

as con sp icuous or as the “ best develop ed In the Clyde area,the Loch Fyn e area

, Sky e , an d elsewhere, its fo ssil shells are tho seo f sp ecies n ow livin g in Sco ttish waters . Clough writes Withregard to the age of the 25 - fo o t beach

,the con sen sus of op in ion

seems to be that the elevation of the beach was comp leted inNeo lithic times .

” 2

In Jamieso n ’

s early accoun t of the strand he statesl

that a riseo f 25 o r 30 feet (above ' Ordn an ce datum is indicated,

an d that itseems to have been very gen eral alon g the shores o f this coun tryHe con cluded that the up lift was un equal ; co n sequently it 1sthe lan d that has risen

,an d n o t the sea that has sun k .

” 3 Fifty y earslaterWright published a sketch - map of the 25 - fo ot beach showin ga maximum height (above Ordn an ce datum of over 35 feet n earLo ch Lin n he

,in Western Sco tland,

from which p o in t the elevationdeclin es— to reach zero on the south—east and n orth - west shores o f

Ireland,in n o rthern Wales

,an d in the North Sea .

4 Wright’s p lacin g .

o f this stran d - lin e do es no t altogether agree with the descriptio n spublished by A . Geikie

,Kin ahan

,

'Hull,and others, but would

in dicate late Neo lithic warp in g .

Acco rdin g to Kin ahan ,the 25 - feet sea beach all aroun d Irelan d

rises and falls very similarly to the levels o f the presen t sea - margin ,

though he adheres to the up lift hyp o thesis as the on ly o n e to be

co n sidered in exp lan ation . The o ld level is marked by cliffs,stacks,

sea- caves, and beaches on op en seab'

o ar-ds they have been largelydestroy ed by waves breakin g at presen t sea - level . From Wicklow,

southward , the strand is at about the .22 ft. con tour . North o f

Dublin Bay it is below the 20 ft. con tour . In the o ld estuariesit has been p laced n early o n the 25 ft. con tour, p erhaps illustratin gthe in fluen ce of the tides in causin g differen t in itial levels . Human

relics and shells o f sp ecies n ow living in the Atlan tic have beenfoun d in the Irish beaches also .

Hull described the 25 - feet terrace as the most strikin g an d

con tinuous o f all the raised beaches of Irelan d,an d correlates

it with the 25 ft. stran d in Sco tland . However,he gives the average

elevation of the Irish beaches as 15 feet . 5 The con trast in elevatio n s

1 A . Ge ikie , The Scen ery of Scotlan d 2n d cd .,Lo n don 1887, p p . 381 - 2 .

C.

'

T . Clough ,The Geo logy of the Glasgow Di strict (Mem . Ge o l . Surv

Sco tlan d) , 19 1 1 , p . 192 .

3 '

I". F. Jamie son , Quart. Journ . Ge o l . So c .,vo l . x x i , 1865 , pp . 188—90 .

4 W. B . Wright , The Quatern ary Ice Age , Lo n don ,19 14 , p . 422 . Accordi n g

to a p erson al commun ication from Mr. Wri ght (November, 19 19 ) the ze roiso base should be drawn con side rably farther south in Ire lan d an d Wale s .

5 G. H. Kin ahan,Man n a l of the Geo logy of Ire lan d, Lon don ,

1878 , p p . 251 - 8

E . I

g

ul l, The Physica l Geo logy an d Geograp hy of Ire lan d, 2n d cd . , Lon don ,

p . 1 7.

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254 Professor R. A . Da ly

the lower Cap e May terrace do es n ot rise bey ond the 20 ft .

co n tour . Is there eviden ce o f such a halt in the “ emergen ce of theTalbo t formatio n 1

Similarly ,the lower divisio n o f the Pen saco la terrace in Florida

,

like the Satilla terrace in Geo rgia . seems to correlate with theRecen t 20 ft . eustatic shift . The Pen saco la terrace “

is a broadp lain ,

risin g less than 40 feet above sea level,and apparen tly

in cludin g two division s, on e bein g less than 20 feet above, an d theo ther from 20 to 40 feet above sea level . ” 2 The greater part o f theSatilla terrace

,which merges in to the Pen saco la terrace , “

is 15 to

25 feet above sea level, but there are a few places which reach an

elevation of about 40 feet . If the coast region were up lifted 15 or

20 feet above its presen t elevation ,

"

a p lain n ow submerged b en eaththe o cean waters would app ear as an emerged terrace ly in g east ofan d parallel to the Satilla terrace , an d separated from it by an

escarpmen t . This p lain would be an alogous to the Satilla p lainin all its essen tial features .

” 3 Sin ce the Pen saco la - Satilla terracekeeps a practically un iform set o f levels for an air- lin e distan ce o f500 miles, the hyp o thesis o f its emergen ce by crustal uplift seems

hardly credible .'

Florida Keys an d West Indies — Vaughan has deduced a recen tsinkin g o f sea - level of from 10 to 15 feet alon g the coral - reef keyso f Florida, an d perhap s 10 to 20 feet alo n g the keys west o fBahia Honda .

4 He described New Providen ce Island of the Bahamagroup as,

“mo stly a p latform from

'

sea level to 20 feet in elevation ”

an d the n eighbourin g An dro s Islan d as havin g the same ran ge ofemergen ce . On New Providen ce Islan d he discovered a wave - cutscarp at 10 feet above water level an d o ther ben ches at on ly3 or 4 feet above the sea

,but he also found a sea - cave at Nico llstow‘

n

Light, which indicates an emergen ce o f about 18 feet . 2 This caseof apparen t con flict 1n the testimon y of ben ch an d sea cave as to theamoun t of level - shifting is strikin gly like that at Tutuila , Samoa

already described .

In Cuba the Se'boruco reef represen ts a recen t un iformemergen ce it borders the coast in most places an d con stitutesman y islets surroun din g the main island . Gen erally these arelow

,standin g o n ly a few feet above the water .

.In Jamaica Hillfound elevated reefs at 25 feet and 10 feet above sea - level

1 Cf. M. Ful ler, Prof. Pap er No . 82 , US Ge o l . Surv 19 14 p . 222 .

2 G. C. Matson an d S. San ford, Water supp ly Pap er No . 319 , U S. Ge o ]

Surv., 19 13, p . 34 .

3 O Ve atch an d L. W. Stephen son ,Bul l . 26, Ge o l . Surv of Ge orgia 19 1 1 ,

p p .

4 T . W. Vaughan A Con tribution to the Ge o logical History of the

Flo ridian Plateau Pap ers of the Marin e Laboratory , Carn e g ie In stitution

of Washin gton ,19 10 , p . 180 . Pre limin ary Remarks on the Ge o logy of the

Bahamas”

: ibid . 19 14 p . 50 . Ye arbo ok No . 13, Carn egie In stitution of

Washin gton ,19 14, p . 230 .

Recen t S in king of Ocean - level . 255

an d states that they are persisten t on the n orth, east, and south - westshores .

I

South America — Acco rdin g to Bran n er, the Brazilian coast showsfeatures in dicatin g recen t emergen ce , the amoun t o f which isvariously described as a few meters ’ ”

to 8 meters . Halle founda

‘‘

very distin ct terrace at 6 meters above sea - level on Gable IslandPatago n ia ,

an d an o ther at 6 meters at the mouth of the Rio Gran deRiver, 48 kilometres from Gable Islan d . The san ds o f the formerterrace bear fossils showin g that the con temp orary sea had a

temp erature higher than that n ow reign in g o ffshore . Halle adds :These low terraces do n ot affo rd

'

an y un question able eviden ce o fan un equal upheaval . ” 3 Andersson describes a sea - cut terraceat 35 meters o n Beagle Chan n el Tierra de l Fuego ,

and say s thatit is the same beach as tho se 0 11 Gable Islan d an d NavarinIslan d . He quo tes Norden skjold’

s discovery of a very markedterrace at about 10 meters above sea - level on Usuaia Pen in sula,Straits o f Magellan - 4

Graham Land,An tarctica — An dersson also discovered a terrace

at 7 meters above sea - level on Graham Lan d,An tarctica ,

indicatin g ‘

upheaval which ‘‘

do es n ot exceed a few meters ”

New Zealand.

— Con siderable atten tio n has been give n by theGovernmen t Geo lo gical Survey to pro ofs of recen t emergen ce

_

in

New Zealan d,with results which may be tabulated as fo llows :

District. Elevation of raised beaches or benches .

Thame s subdivision Maximum over 25 fe et (datumMiran da

,across Firth o f Thames 10 to 12 fe et above high water mark .

Waihi - Tairua subdivision Be n che s seve ral fe et above high wate rmark

Aroha subdivision Corre lated with the last.

Oamaru subdivision 12 ft . be n ch ; accompan y in g beach withRe cen t fossi ls . Pap akaio coastal p lain

at 15 to 25 fe e t above se a - leve l

Australia — Acco rdin g to Andrews, the numerous coastal p lain s,emerged beaches, an d ro ck - ben ches of New South Wales suggestan apparen t e levation - of the shorelin e to the exten t of a few feetin very recen t time ” . The heights o f the beaches vary from 1 to

15 feet above high - Watermark . Similar indication s o f the apparen televation of the shorelin e for a few feet are to be found alon g thewho le eastern side o f Australia .

” The cause is attributed to eitheran apparen t rise of the lan d,

or a retreat o f the sea , to the exten to f a few feet ” .

6Siissmilch believes that the New South Wales

1 R . T . Hi l l,Amer. Journ . Scie n ce vo l . xlviii

,1894 , p . 203 ; Bul l . 34 ,

MuseumCompar . Zo o logy , Cambridg e , Mass 1899 , p . 99 . Systematic discussion o f

the Atlan tic Islan ds would in clude Be rmuda, where R . S. Tarr (Ame r: Ge o l .vo l . x ix

, 1897 , p . 293) foun d a recen t te rrace reachin g 15 ormo re fe et above sea .

2 J . C. Bran n er, Bul l . 44 , Museum Comp ar . Zo o logy , Cambridge ,Mass ,

1904 , p . 170 et an te .

3 T . G. Hal le,Bull . Ge o l . In st . Un iv . Up sala , vo l. ix , 19 10 , p p . 99

,1 17 .

4 J . G. An dersson , Bul l . Ge o l . In st . Un iv . Up sala vo l . viii , 1908 , p . 182 .

5 Ibid . , p . 57 .

6 Bul le tin No . 10 , 19 10 , p . 29 ; No . p . 50 ; No . 16 19 13, p . 77 ;No . 20, 19 18 , p p . 1 12- 13 an d p . 4 .

2 56 Professor R . A . Baby

coast belt shows recen t up lift to the exten t of about 10 to20 feet . ” An estuarin e deposit at Largs , with surface at 15 feetabove high - water

_

mark, has y ielded mo re than 30 sp ecies of shellso f an imals n ow livin g.

in the adjacen t water . Similar discoverieson the co ast of Queen slan d are rep o rted by Jack an d Etheridge ,the emerged beaches an d p lain s (lo cally with recen t fo ssils) havin gheights o f from 10 feet to 20 feet above sea - levelCadell n o tes that the raised beaches of Western Australia

are from 10 to 15 feet above sea - level: On e of these is from 12 to

18 miles wide,an d exten ds 25 miles in land . The beaches con tain

recen t marin e shells .

2

Pacific Islands — Man y local , recen t , n egative shifts of sea—levelhave been reco rded in the Pacific archip elago es, where syn theticstudies are n eeded in so man y lin es . A few o f the records will sufficeto raise the questio n whether the last shift of level in Samoa affectedthe who le Pacific basin . After his reco n n aissan ce o f the Paumotus,

Agassiz wro te Nearly all the islands have been elevated a verymoderate height an d probably to about the same height . ” He givesthe figure for Niau as

'

n o greater than 20 feet an d for Ran giroa

as 15 to 16 feet . 3 At Fun afuti o f the Ellice group ,David and Sweet

found the recen t n egative shift of level to be at least 6 feet an dalmo st certain ly 16 feet In an o ther passage they write Theremust have been a lan d- elevation or a sea - sinkin g o f at least 9 to10 feet . ” 4 For the New Hebrides Mawso n rep orts sea terracesben ches, and raised sho re debris o r coral in San to ,

Efate , Ep i ,Malekula

,Pakea

,an d Hui Islands , at heights o f from 5 to 15 feet .5

In his Murray Islan d rep ort Mayo r writes In common with o therislan ds of the Torres Straits region ,

whether vo lcan ic ,calcareous ,

o r con tin en tal in character the Murray Islan ds exhibit a recen tlyemerged shore p latform about 3 feet above the presen t high - tidelevel . ” 6

On Bird Islan d o f the Hawaiian Chain ,Elschn er found

a“ level terrace a few feet above sea - level ."'

As shown in Samoa an d in the Bahamas,the observed heights

o f wave - cut ben ches o n o cean ic islan ds are likely to be 6 to 12 or

more feet below the high - tide level rulin g at the time of their cuttin g .

Raised coral,to o ,

is liable to give to o small a value for a n egative.

1 E . C. An drews , New South Wale s Han dbo ok, Brit . Assoc . Adv . Scien ce ,

19 14;pp . 525 . 532 C. A . Sussmilch,In troduction to the Geo logy of New South

Wales, Sydn ey , 19 1 1 , p . 154 ; R . L. Jack an d R . Ethe ridge ,

Geo logy an d

Pa laeon to logy of Queen slan d an d New Gu in ea , Lon don ,1892 , p p . 614 ff .

3 H. M. Cade l l,Tran s . Edin burgh Ge o l . So c .

,vo l . vii , 1897 p . 179 .

3 A . Agassiz , Memo irs, Museum Comp ar.

' Zo o logy , Cambridge , Mass

vo l . xxviii , 1903, p . 20 .

4 T .W. E,David an d G. Swe e t, The A to l l of Fun afuti , Lon don ,

1904 , pp . 68 ,84

,85 .

5 D . Mawson , Proc. Lin n . Soc . New South Wale s, 1905, p t . iii , p p . 400 if .

6 A . G. May or,Pap e rs from the Departmen t o f Marin e Bio logy , Carn egie

In stitution of W’

ashin gton , vo l . ix , 19 18 , p . 9 .

7 C. Elschn e r, The Le eward Islan ds of the Hawaiian Group reprin t from

the Sun day Advertiser, Hon o lulu; 19 15, p . 9 .

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Recen t Sin kin g of Ocean - leve l . 259

CONTEMPORANEITY AND AGE OF THE STRANDS.

A second test of the eustatic chan ge is n aturally to be foundin the expectation that the de leve llin g should be essen tiallysyn chron ous in all parts o f the o cean . In fact

, observers dwell o nthe recen cy of the sea - level shifts registered in all o f the illustrativecases . Fossils in the St . Lawren ce

,Sco ttish

,Irish

, Cuban ,

Patagon ian ,New Zealan d

,Australian

,Fun afuti

,Murray Islan d,

New Jersey , Mary land,Georgia, an d Florida beaches, reefs, or

co astal plain s belon g to species n ow livin g in the adj o in in g seas,or

,excep tion ally ,

to sp ecies n ow livin g in slightly warmer water .

Great recen cy is also shown by the'

relatively small damage don e byerosion to the strand marks

,except in the case o f those exposed to

p owerful surfThe beaches o f the higher latitudes are clearly p ost - Glacial,

an d also o f date later than the po st G— lacial uplifts fo llowin gdeglaciation . Brogger puts the completion of the last 4 metre to8 metre emergen ce of the Christian ia region at about the y ear 500 B .C .

The developmen t of the corresp on din g sea - cliffs, ben ches , and o therstran d marks is referred by him to the late Tapes (Neo lithic) period,between 1400 B . C . an d 2400 B . C . All Tapes time is taken to liebetween 1400 an d 6700 B .C . Durin g the late Tapes periodthe Christian ia climate was about 2° C. warmer than n ow .

1 Tracesof Neo lithic man have been foun d in the 25 ft . beaches of theBritish Isles .

“The emergen ce o f this beach in North Ireland seems

to have been completed durin g Neo lithic times .

2

Perhaps fuller direct “ eviden ce for con temp oran eity amon g thelowest beaches may be discovered through the use of fo ssils . It issign ifican t that the fossils in the Patago n ian beaches, like those o fNorway , betoken water warmer than the adjacen t sea .

Simultan eous emergen ce for the man y separate region s is themore credible because o f the similarity in the histories of theirrespective coasts before emergen ce . Repeatedly on e en coun tersthe description o f terrace

,ben ch

,or beach n ear the 20 ft . level

as the best developed, the most coh sp icuous, or the mo st p ersisten tin a region characterized by raised stran d marks illustration sare n oted in the forego in g table . Thus, the differen t region s musthave had sea - level n early con stan t for a con siderable time , durin gwhich the stran d marks were well in cised . This widespreadaccordan ce itself must deep en suspicion that local diastrophismhas n ot been resp on sible for the

'

recen t emergen ce o f so manycon tin en tal an d island coasts .

In con clusion , the facts in hand app ear to permit belief in thep ossible syn chron y of the differen t stran d markin gs and emergen ceshere con sidered, but this secon d test of the gen eral hypo thesis alsoleads more surely to question s than to defin ite an swers .

1

.

905W0

- C. Brogger, No rge s ge o l . Unders , No .

°

31 , 1901 , p . 713, an d No . 41 ,

2 W. B . Wright, The Quatern ary Ice Age , Lon do n ,19 14

, pp . 384 - 5 .

260 Pr ofessor Da ly— Recen t Si n ki n g of Ocean - l eve l .

CAUSE - OF THE EUSTATIO CHANGE .

Before the fact is ’

established it would be idle to dwell overmucho n the explan ation o f a 20 ft . drop in o cean level . If lan ds in bo thhemispheres, in high an d low latitudes

,emerged simultan eously

an d to a n early equal amoun t, the cause o f the emergen ce can n o tbe found in a chan ge in the earth’s cen tre of gravity n or in a chan gein the speed o f her ro tation . There is n o eviden ce compellin g beliefthat the ocean basin has been so en larged in recen t time as to causea n egative 20 ft . shift o f sea - level . More hopeful is the hyp o thesiso f an in crease in the vo lume o f existin g , n on - floatin g glaciers, anin crease takin g place a few thousan d y ears ago . If the An tarcticice - cap were then thicken ed to .the average amoun t o f about 700 feet,an average sin kin g of sea—level to the exten t of n early 20 feet wouldbe in evitable .In favour of this suggestion would be eviden ce of a Worldwide

oscillation of climate,like that which seems to have affected the

Christian ia regio n in Recen t time . If the who le earth was in theTap es p eriod a little warmer than n ow,

less water may have thenbeen taken from the ocean to build the ice - caps ; sea - level was a

little higher than at presen t . The o scillation as a who le would bebut an in ciden t in a series o f climatic chan ges which began withthe

‘

op en in g o f the Glacial p eriod .

CONCLUSION .

The facts on which the hypothesis o f .a gen eral post - Glacial fall .

of sea- level is based belon g to three groups .

Because of the recen cy o f stran d lin es n ow about 20 feet abovehigh - tide level

, man y of these lin es should'

n o t have undergon eimp ortan t deformation

,and if their emergen ce was due to the eustatic

shift their accordan ce o f level should be observable . No twith

standin g the difficulties atten din g a can vass of the wo rld’

s coastlin es

,a compariso n o f published Observation s seems to show that

the sp eculation will bear the test o f a fuller in duction founded on

sp ecial field work .

Naturally less troubled by the dan ger of subj ectivity ,the con

elusion s drawn from a study of the Micmac terrace or the lowestcoastal - plain terrace to the southward o f New York City are n ow

p erhaps more comp ellin g . Practical un iformity for the terracelevel alo n g 300 miles of coast in the o n e case an d alon g n early

miles o f coast in the o ther is certain ly n ot exp ected o n theup lift hyp o thesis, which likewise do es n ot easily exp lain thestrikin gly accordan t levels of Samoan ben ches at p o in ts o n ly 75miles apart .A third group of facts, relatin g to the n ecessity of . syn chron y fo r

the differen t strands abandon ed by the sea ,is meagre , but so far as

it go es this eviden ce p ermits the main hypo thesis, an d its an alysissuggests methods for future research .

The combin ation of all three groups of observation s is much

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262 Dr . C; Key es— Isostasy i n the Rocky Mou n ta i n s .

Didyrn ograp tus bifidus Hall .Didymograp tus stabilis Elles Wo od .

Didyrn ograp tus n anus Lapw.

From the Ellergill Beds . exposed in the lower part o f Eller GillI have obtain ed Glyp tograp tus den tatus Sin ce thesefossils are characteristic o f the Didyrn ograp tus bifidus zon e, it wouldseem that the Milburn Group and the asso ciated Ellergill Bedsbelon g to this zo n e , and that here

,too , vo lcan ic activity began

in Upper Aren ig time .In con clusion ,

I desire to express my sin cere than ks to Miss Ellesfor havin g determin ed the grapto lites and permittin g me to se e her

determin ation s, and to Pro fessors Sibly an dMarr an dDr . Wo o lacott

for advice .

Iso static Measure o f the Ro cky‘

Moun tain s.

By CHARLES KEYES, Des Mo in es, Iowa .

AMONG the en isled high p lateaux of Eastern Utah the brillian tisostasy theory had its birth . When these arid moun tain s

first became the subj ect o f special description ,about 1880, n o . such

thin g as a distin ctive desert geo logy was en tertain ed . Po ssibilityo f a defin ite geo graphic cycle in land sculpture was on e o f the modernearth con ceptio n s yet un dreamed . Comp eten cy of the win d '

as a

gen eral erosive agen cy was n ot -

y et established . Operatio n o f

ep eirogen ic movemen ts was little un dersto od . Omission o f suchbasic con sideration s n ecessarily led to curious aberration in in terpretation of the phen omen a presen ted by lan ds o f little rain .

“ 1

Fo llowin g closely the rather un scien tific Powe llian po licy o f

geo lo gical saisissemen t, Cap tain Dutton en tirely missed the largerphy siographic sign ifican ce of his wide Observation s on the prodigiouserosion which the Utah region hadman ifestly un dergon e in relativelyrecen t geo logical times . He readily fell in to sp eculation s alon g. o therlin es . With him in '

ductive reason in g to ok a tecton ic rather thana physiographic turn .

Prin cipal amon g the Dutto n ian meditation s was an estimateo f the crustal effects of sedimen tal loadin g an d un loadin g througherosion . Revivin g astro n omer Herschel ’s well - kn own viewthatareas of sedimen tation should be region s of in sinkin g o f the earth’scrust, the en deavour was to show that the con verse of this was alsotrue

,an d that the Utah and Great Basin regio n s, from which

en ormous vo lumes o f ro ck waste had been so recen tly removed,should disp lay the eviden ces Of con tin ual an d n o table upraisin g .

The hyp o thesis of isostasy was just begin n in g to take form .

With ben t o f min d tecton ic, Dutton turn ed ey es to the westwardfor substan tiation of his hyp o thesis . In the Basin ran ges he believedthat he had found satisfactory pro ofs . With Gilbert, Powell, andRussell he fan cied that those desert moun tain s were floatin g o n theearth’s soft in terior, much after the mann er of ice - cakes in a river

Dr .

'

C. Key es— Isostasy i n

'

the Rocky Moun ta in s . 263

at time o f the sprin g break - up . To this quartette the erosio n alderivation o f the Basin ran ges seemed en tirely out o f question . Thep o ten cy of eo lation in arid lands was little suspected .

In the seven ties of the last cen tury Dutton was really un ableto turn his atten tion profitably to the Rocky Moun tain s rearin gtheir p eaks to the east o f him, in

'

Order to test his hypo thesis .

Geo logically the Co rdillera was to o little kn own . Its exten t was to ovast to draw up on in hasty con clusion. It required half a cen turyo f un in terrup ted investigatio n by man y person s to dislodge the factsthat had critical bearin g upon fan tasti c musin gs . N ewer eviden cesapp ear con clusive .The Ro cky Moun tain s seem to be excep tion ally well suited

to determin e the span of isostasy . They o ccupy a tract which fromthe earliest geo logical times has un dergon e con tinuous diastrophico scillation . The area' is o n e which has been rep eatedly uplifted .

It is on e which has suffered again and again exten sive p lan atio n .

T-he orographic chan ge is n ever so great as en tirely to obliteratethe salien t features o f the differen t movemen ts . Later upraisin gs

an d down - sinkin gs are esp ecially well marked . The geo logicrecord of even ts is unusually full .Sin ce Palaeo zo ic times the Southern Ro ckies have experien ced n o

less than four distin ct and n otable up liftin gs . In the same time theyhave suffered a like number Of total effacemen ts . Each o f thean cestral Ro ckies has appeared n o less maj estically than themoun tain s of to - day . Each of the o ld levellin gs has been down tothe surface of the sea . Pen eplan ation has been as perfect as isprobably ever attain ed; Great p lan ation p eriods were durin gComan chian

,Laramian

,Mio cen e

,an d Recen t times .

Coman chian p en ep lan ation is particularly widespread . It affectsthe who le contin en tal interior from the Rio Grande to HudsonBay and from the Sierra Nevada border to the Mississippi River .

Even to this day its essen tial characters are un usually well disp lay ed . Throughout its broad expan se the great Dakotan sandston eco n sp icuously marks its stratigraphical p osition and preserves itsfeatures . The

_

o ld plain is on e of the smo o thest kn own in all

geo logical history . On ly in a few places do there exist “

an y'

un

con sumed residuals stan din g out as low mon adn ocks above thegen eral level .Accordin g to the fundamen tal premise o f the isostasy hypothes1s,

moun tain s co n tinually rise because o f the removal of their summitsthrough erosion , thus lighten in g the local crustal loads . On theo ther han d

,accordin g to Herschel

,areas o f sedimen tation , or

loadin g , should be tracts of n o table crustal in sinkin g . Sin gularly ,the Jurassic an cestral Ro ckies do n ot app ear to have grown higheras their substan ce wasted away . They allowed themselves to beworn down to the very level of the sea .

After reachin g sea - level,when all their p ositive vo lume had

van ished, the tract which the Rocky Moun tains on ce occupied,

264 Dr . C. Key es— Isostasy inthe Rocky Moun ta i n s

in stead of continuin g to rise,

.or at least remain station ary , pro ceedsto sink . Indeed

,the area may have begun to sin k lon g before it

reached base - level . At an y rate depression is active un til the o ldplain attain s an ho rizon more than two miles ben eath the surfaceo f the o cean . Where on '

ce loft moun tain s p ierced the sky , marin esedimen ts feet in thic n ess accumulate . "

In sp ite of theremoval o f its former great lo ad the n et result of the region al verticalmovemen t is n o tably n egative .Neither do es the in sin kin g of the earth’s crust in this reg1o n

app ear to have taken p lace p ari passu with exten sive tran sferen ceo f sedimen ts . Cretacic depression man ifestly in itiates itself lo n gprior to the begin n in g of the sedimen tal loadin g , perhaps b eforethe moun tain s were completely demo lished . Then , curiouslyen ough, so so on as the en ormous loadin g is fin ished the region isup lifted again in to lo fty . ran ges, as towerin g,c p erhaps, as an y whichappear befo re or sin ce . In stead o f the sequen ce o f even ts satisfy in gthe isostatic equation s, the very reverse proves true all through .

Thus is region al un loadin g succeeded by crustal down sinkin g ,and orogen ic upraisin g is accomplished under maximum load .

Surely some orographic force o ther than the isostatic on e is at work .

An esp ecially n o teworthy feature con cern in g the Ju assic

revo lution in the Southern Ro cky Moun tain region is that it 1s n otan iso lated o r un con n ected catastrophe . An iden tical sequen ce o feven ts is repeated a little later in Laramie time, an d again inMiocen e time . To - day the same pro cess is go in g o n for a fourth time .Durin g the ep och when Laramian sedimen tation was proc eedin g

around the an cestral Ro ckies,the latter were themselves razed to the

level o f the sea . Un der a prodigious load of sedimen ts, more thantwo miles in thickn ess

,the tract is up lifted a distan ce of between

four and five miles ; an d that before it is appreciably un loaded .

Again it is worn down to the o cean level . With the lighten in g o f

load on accoun t o f erosion there app ears to be n o recogn izableupli ftin g . After base—levellin g , the area in stead of rising sinks,un til the pen ep lain is buried un der miles of Tertiaries .

In the Miocen e p eriod,for a third successive time , are the Ro cky

Moun tain s reared to lofty heights, on ly to be reduced to a low- lyin gp lain . Recen tly , n o table up liftin g is rep eated . The rejuven atedstreams are n ow about comp letin g their can yo n

- cuttin g . On theflanks the win ds are levellin g an d lowerin g the surface . Soon themoun tain s will be turn ed in to p lain . Are they destin ed to a n ew

en gulfmen t an d a n ew sinkin g a mile or two or more ben eath thewaters o f the sea ? Exp erien ce o f the past for three successivetimes proclaims the affirmative .In all four orogen ic cy cles the p ro cedure is the same . Removal

o f load is n ot accompan ied by further upraisin g . Ro llin g o f ocean icwaters over the tract precedes region al loadin g . Maximum arealloadin g is fo llowed by great upliftin g . Every stage is met withphen omena diametrically opposed to that which isostasy logically

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266 S . IWelmore— Metamorp hisni at Carr ock Fe l l .

At best,then

,moun tain gen esis app ears to be merely a feeble

expression o f the larger telluric prop erties of our globe . As suchit is ‘fit subj ect for most rigid analysis .

The Me tam o rp hism o f the Carro ck Fe ll Gabbro ; W ith

a No te o n the Origin o f the Sulphide Ve in s o f the

Caldbe ck Fe lls.

By SIDNEY'

MELMOEE,B.Sc. ,

WITHIN the last two y ears a cuttin g has been made at the southeast '

corn er. o f Carro ck Fell, a few yards n orth o f the villageo f Mosedale, for the purpos e o f obtain ing road- metal . This haso p en ed an in terestin g section n ear the margin of the in trusion .

The ro cks exp osed comprise two varieties of gabbro an d en closedEyco tt lava . Of the two typ es of gabbro , that n ext the lava is of thequartz bearin g variety ,

exhibitin g the prevailin g dark -

green tin tin the han d sp ecimen ,

and carries large flakes o f bio tite . This issucceeded by the same typ e o f gabbro ,

but in a highly metamo rphosed con dition ,

at on ce eviden t in the hand sp ecimen ,which is

lighter in co lo ur,primarily owin g to the decomp osition o f the felspars .

Examin ation o f the first gabbro i n thin section s un der themicro scop e shows that it also has been metamorpho sed, thoughin a lesser degree than the lighter co loured vari ety . The felsparsare o f the o ligo clase - andesin e typ e ; the cen tral parts o f the crystalsare in a saussuritic con ditio n

,while the en ds are free from decom

p ositio n . This condition is particularly n o ticeable in the largercrystals, and suggests secon dary deposition of material differin gslightly in chemical comp osition from the origin al matter, sin ce thecrystals show zon ary extinction , and the twin - lame l lse seem to

broaden out somewhat at the en ds . The extin ction an gle is greaterfor the in n er than for the outer zon es . The crystals themselves are

surroun ded an d cut up by irregular strin gs o f chlorite . Some o f thefelspars o ccasion ally con tain a few minute irregularly shap edco lourless p lates, depo larizin g in co lours o f a high order, an d are

doubtless sericite , though they are to o small fo r iden tification .

The origin al pyroxen e has been converted in to pale -

greenserp en tin e , which o ccurs in areas with amo re o r less sharp ly defin edoutlin e , an d havin g a p laty structure . The cen tral parts of theseareas are in some cases o ccup ied by small grain s of magn etite ina fin e -

grain ed mosaic o f stro n gly depo larizin g material , and in

o thers by chlorite . Separate fragmen ts o f chlorite "

also o ccur

exhibitin g a fibrous structure . Bio tite is largely altered to magn etite .This chan ge seems to have progressed from on e side o f the micafiake to the o ther, and can be found in all stages of developmen t .A

'

sp ecimen p icked out o f the heap of material already quarriedcon tain ed a lay er of p ecto lite, about 3 5 cm . in thickn ess , surroundedby rock iden tical in every respect to that already described, except

S .

‘Melrn or e— Metamorp hism at Carrock Fel l .

perhap s that the biotite is everywhere comp letely convertedmagn etite .The p ecto lite gave on an alysis

S10 2A120 3 an d trace F6 20 3CaO

SrO

MgONazO

K20

Combin ed water

99 46

Sp e cific gravitySmall masses Of calcite about 1 cm . acro ss an d con tain in g traces

o f stron tium are somet1mes foun d with the p ecto lite . 1A section cut from this p ecto lite sp ecimen showed un der the micro

scop e a thin lay er o f white mica between the p ecto lite an d

surroun din g rock,while a n arrow strin g o f this mica ran parallel

to the main vein of p ecto lite an d at some d istance from it . Flakes.of sericite can be seen in the felspars adjacen t to the vein . Analysiso f the ro ck itself showed on ly a trace of carbon dioxide , with 00 74 p ecen t sulphur .

The greater part o f the lighter - co loured gabbro ,which is about

2'

feet in thickn ess at the margin o f the in trusio n , con sists o f

p lagio clase in a more advan ced state o f decay ; the who leo f the crystal is reduced to a tran slucen t mass

,through which the

co re o f previo usly decompo sed matter can still be seen in somein stan ces .

Almo st co lourless serp en tin e o ccurs in places,asso ciated , with

magn etite in large , approximately square section s , an d in . smallgranular in clusion s , while separate areas o f fibrous chlorite are alsopresen t .Occasion ally small hook shap ed areas o f iso tropic material with

felspar in clusion s can be detected between the felspar crystals .

There are also a fewwell - defin ed crystals , givin g a biaxial in terferen cefigure and p ossessin g very weak double reflection ,

that probablyrepresen t a member o f the zeo lite group . The quartz presen t inthe rock is full of liquid in clusion s, the len gth o f the larger o f thesebein g about 00 06 mm . an d the diameter o f the bubble 00 015 mm .

This rock, which represen ts a maximum degree o f metamorphismo bserved

,loses 2 12 p er cen t o f its weight o n ign itio n . For the

n ormal quartz gabbro Dr . Harker gives the loss o n ign ition as

1 50 p er cen t . 2From the above accoun t it may be con cluded that hydro thermal

metamorphism has taken p lace at the margin o f the gabbro in trusio n ,

resultin g in the serp en tizatio n o f the origin al pyroxen e , accompan ied1 The material taken for an aly sis was fre e from calcite .

2 Quart. Journ . Ge o l . Soc vo l . I, 1894 , p . 323.

268 S . Melmor e— Metamorp hi sin at Carr ock Fel l .

by local sericitization and the formation o f -

p ecto lite , with exten sivealteration o f the felspars in the most in ten se stage .Eviden ce o f similar chan ges is to be foun d in the case o f thein terfusion ro ck between the gabbro and gran op hyre . At the fo oto f Furthergill Syke there is a variety o f this ro ck in which calcite(without stro n tium) is un iformly distributed throughout the mass,

but o therwise corresp on din g to that marked No . 2 in

Dr. Harker’s sectio n across Furthergill Syke, the sp ecific gravity o f

which he found to be The sp ecific gravity o f this alteredvariety is 2 68 . An alysis showed 0 80 p er cen t o f carbon dioxide ,corresp ondin g to 18 2 p er cen t calcite an d 00 23 per cen t sulphur.

Amon gst the heaps o f“

min e refuse at Roughten gill are to be foundspecimen s o f themore basic variety of in terfusion ro ck

, co n tain in gamygdules and small offsho o ts of calcite surrounded by a thin layero f p in k felspar. This calcite con tain s traces of strontium .

It has lo n g been supp o sed that the Carro ck Fell complex representsthe fo cus o f ign eous activity that gave rise to the sulphide vein sof the Caldbeck Fells . The structural relation ship and o ther con

sideration '

s p o in tin g to this con clusion have been demon strated byMr. Po stlethwaite . 2 Further eviden ce is also afforded by the wayin which the metallic con ten ts of these vein s fall o ff as we recedefrom this cen tre

,so that at Po ttsgill an d Ruthwait

’

e the gan gueo f quartz an d bary tes makes up practically the who le of the veincon ten ts . It seems reason able , therefore , to in fer that the formationof the sulphide vein s is to be correlated with the typ e of metamorphism already described . It is n o teworthy that though thesulphur con ten ts o f the n ormal ultrabasic gabbro from Furthergill

Syke '

is co n siderably below the average for this typ e o f rock, and thatthe gran ophyre at the top o f Carro ck Fell is also low in sulphur,there is, n evertheless, an in crease in the amoun t o f this elemen t atthe margin o f the in trus ion , due either to magmatic segregation or to

removal of sulphides . from dep th by the agen ts that have broughtabout the margin al metamorphism . The percen tage of sulphur inthe rocks under con sideration is

Iron - ore gabbro

Gran ophy reIn terfusion ro ckSerp en tin ized quartz -

gabbro

From this p o in t of view the sulphide vein s are to be regarded as

co n tact vein s in the sen se of Beyschlag, Vogt, andKrusch’s defin ition ,

i . e . as fissures stan din g op en in the con tact zon e fil led withore dep osited from so lution s issuin g from the magma

Quart. Journ . Ge o l . So c. , vo l . l i , 1895, p . 133.

Tran s . Gumb . an d We st. Asso c. Lit . an d Sci . , vo l . xv,1889—90, p . 78 .

Bey schlag , Vogt, an d Krusch , The Dep osits of the Useful Min erals an d

Ro cks Tran s . Truscott, vo l . i , 19 14 , p . 69 .

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21

70 G. W. Butler— A Cha lkFaun a n ear Reigate .

except in the case o f Cephalop od septa,seems always to break so

as to Show the outside on ly o f these casts,which

,if n ot smudged,

are al l right for species easily iden tified by the extern al form an d

markin gs, but are n ot so go od for the small Lamell ibran chs .

Some o f the best an d mo st in terestin g specimens were foun d bymy son

,while the most in terestin g o f all , the Lingula,

‘

was foun d

by"

Miss E . C. Herdman , o f Newn ham Co llege, Cambridge .This little Lingula is but ’

13 in .,or 3%mm . in len gth , but by

comparison o f the p o in ted end (X 45) with that o f the livin gL. an atin a ,

it can ,I thin k

,be iden tified as a dorsal valve . Of course ,

we kn ow that Lingula was livin g , somewhere, in Chalk times, butits remain s seem usually to be found in deposits rich in 'terrigen ous

material , such as clays or san ds,and so far as I can learn “ there are

o n ly two p revious records o f Lingula from the Chalk of the BritishIsles

, (1 ) from the very bottom o f the Lower Chalk within 3 feetOf the Upper Green sand, from the ChloriticMarl at

'

Rye HillFarm

,3 miles east o f Maiden Bradley ,

1and (2) the beautiful small

specimen in the Jermyn Street Museum,presen ted by Clemen t

Reid,from the topmost (Ostrea lun ata) zon e o f the Upp er Chalk

of Britain ,from Trimin gh

'

am fi‘

So an yo n e findin g Lingula, however small,in the Chalk should

carefully preserve an d record it . We may thus perhaps learnsomethin g at on ce about Lingula an d about the Chalk .

The salien t feature of the co llectio n made at this spo t is the largen umber o f Baculites baculoicles . Some pieces o fChalkMarl

,weighin g

as clean ed up on ly 2 o z . con tain n in e separate Baculite fragmen ts "Some

.

sp ecimen s o f the later formed, obliquely ribbed, p ortion o f the

shell,show the slight curve that o ccurs n ear the aperture of the full

grown shell ; an d o ther sp ecimen s of the earlier,smo o th portion

break acro ss at the position o f the septa .

Man tell 3 says that this Baculite o ccurs in “ the_

South Down sin every marl pit of the S.E . part o f Sussex ’

In the NorthDown s it is recorded 4 from this zon e in the Medway cut ; but

o therwise I kn ow o f n o previous record o f it_

from this zon e in theNorth Down s o f Ken t o r Surrey ,

an d makin g a special search myselffrom Betchworth to Reigate in clusive , the on ly p lace where I foundBaculites in the A . varian s zon e is the small lower pit o f the Bucklan d Limeworks and there comparatively few and p oo r sp ecimen s .

I have,however, foun d Baculites baculoides in the Melbourn

Ro ck bo th at Betchworth Pit an d also at on e of the small pitsn orth east o f the exp o sure here described .

I failed to fix the on us o f n amin g my casts on someon e else ,so the blame for the list must rest on me ; but I should than k

1 Jukes - Brown e an d Scan es , Quart. Journ . Ge o l . So c . vo l . lvii , 1901 , p . 1 17 .

2 Mem . Ge o l . Surv . , Cretaceo us , vo l . iii , 1904 , p . 482 [A smal l sp e cime n

from the H. subg lobosus zon e of Che rry Hin ton has be en foun d re cen tly an d

is n ow in the Sedgwick Museum , Cambridge— ED . GEOL . MAG . ]

3 Fossi ls of the South Down s 1822 , p . 123.

4 Mem . Ge o l . Surv.,Cretaceous

,vo l . ii , p . 50 .

Sir N. Y’

ermo lofi—é Diatom Ear th i n Californ ia. 271

Mr . R . B. Newton,F.G.S ,

and Mr . H. A . Allen , F.G.S ,for kind

sympathy an d facilities, and»Professor G. A . J . Co le, an d

Mr . H. Wo ods,

for kindly an swerin g queries as to reco rdso f Lingula from the Chalk of Irelan d an d Britain respectively .

The Diatomace o us Earth o f Lomp o c,“

San ta Barbara CO . ,

Cal ifo rn ia .

By Sir NICHOLAS YERMOLOFF, F.L .S ; with .,a

Prefatory No te by Dr . A . SMITHWOODWARD ,F.R .S.

LAST year Mr . J . L . Bo squi gave to the Geo logical Departmen to f the BritishMuseum part o f a fo ssil shoal o f herrin gs foun d

in a marin e dep osit o f diatoms, n ow bein g worked for commercialpurposes as celite in San ta Barbara CO . , Californ ia . The speciesrepresen ted has sin ce been n amed Xyn e grewby Professors Jordanan d Gilbert, 1 who exclude it from the genus Clup ea on accoun t o fits thicker en amelled scales

,en amelled op ercular bon es, an d stron g

ven tral scutes . The matrix,examin ed un der the microscope , proved

to con sist so comp letely o f diatoms an d o ther siliceous organ i sms

that it seemed desirable to'

submit them also to special examin ation .

I was therefore fortun ate in en listin g the services o f Sir Nich‘

o lasYermo lo ff, whose extended studies o f such organ isms make hisdetermin ation an d discussion Of these n ew fossils o f particular value .His n o tes form an in terestin g supplemen t to the fo llowin g shortaccoun t o f the depo sit, which was g iven by Dr . Fran k M. Andersonto Professor Jordan (op . cit .

,.p

The white Shales about Shorb an d El Moden a are well kn ownto be diatomaceous, and often con siderable bodies o f these rocks,that is a considerable thickn ess o f them ,

is comparatively free fromgrit . I have been accustomed to regard these shales as o f Puen teage , as I believe they have been classified by Dr . Arn o ld,

an d I havebeen o f the Op in ion that the Puen te formation is middle or lowerMiocen e in age , and is the equivalen t o f the Mon terey , taken in thatsen se .The Puen te group is certain ly n ot the base of the Mio cen e i n

the region about Lo s An geles, an d m the localities men tion ed l n

y our letter, n amely Shorb an d El Moden a,the beds are n ear the

middle or a little below the middle o f the Mio cen e section .

I presume y ou have some in formation regardin g the large numbero f fo ssil fishes foun d in the diatomaceous beds o f n ear the samehorizon some 3 or 4 -miles south o f Lomp o c, San ta Barbara Coun ty .

The rock here is almost en tirely made o f diatom material some 600to 800 feet thick .

2

1 D . S. Jordan an d J . Z . Gilbe rt, Fossi l Fi she s of Southern Californ ia (Le lan d

Sitan ford Jun io r Un iversity Publicatio n s, Un iversity Se ries, p . 25 , withgure s0

2 The maximum thickn ess was subsequen tly stated to be 1 ,400 fe e t byJordan Gilbert,Fos si l Fishes of the D iatom Beds of Lomp oc Ca liforn ia

(10 0 . cit ., 1920, p .

272., Sir N. Yermo lofi

p—f Diatom Earth i n Ca l iforn i a .

I believe that the diatoms or the marin e species o f theMo n tereygroup , are , o r were, n o rthern forms

,an d lived in the co o ler waters

o f the No rth Pacific o f the Mio cen e,and were brought south by the

o cean curren ts o f the time,an d were trapp ed and imp ounded in

such favourable places as were found alon g the Pacific coast of thep eriod .

Such favourable p laces were lo cal , an d more or less lan d- locked,

o r pro tected areas of the sea,free from sedimen tation from the land,

and where the surface waters o f the sea were free to en ter an d

escap e, but where they were detain ed lon g en ough to lose their co nten ts Of n orthern forms un der con dition s of temp erature to o highto permit their survival . It app ears to me that the dep o sits o f

diatomaceous strata, as they are kn own l n Californ ia,are al l more

o r less lo cal,an d in their o ccurren ce an d distribution con form to this

idea .

I have also imagin ed that the climatic con dition s of the coastin middle Mio cen e times were differen t from those before an d after

,

for there 1s a well kn own chan ge 1n the character o f the sedimen tso f the Miocen e

,those of the middle bein g largely - organ ic, an d those

o f the lower an d upper Mio cene bein g gen erally coarse detritalmatter in which the o rgan ic con ten ts are in appreciable .It may be that physiographic chan ges in the con tin en tal border

an d in the o cean curren ts could have brought about these differences1n sedimen ts

,but there are certain established facts that po in t to

great climatic chan ges durin g“

Mio c‘

en e times .

—'

A . S. W.

The siliceous remain s in the fossil deposit of Lompoc belon g totwo main and domin atin g group s o f organ isms

,Dictyo chideae and

Diatomaceae . The dep osit co n tain s also a'

few Radio laria, somesiliceous spon ge - sp icules, and a few remain s o f Lithasteriscus .

The Dictyo chideae are very n umerous, in fact n early as n umerousas the Diatoms . This is remarkable an d rather peculiar, because ,although the genus Dictyocha has as a rule a very wide distribution ,

bein g presen t in n early all fossil Diatomaceous depo sits, y et itgen erally do es n ot appear in o ther dep osits in such domin atin gn umbers as in Lomp o c . Thus it is presen t in the fossil dep ositso f Richmon d, Va . ,

o f Simbirsk , Mo rs,Oran ,

Oamaru, Sen dai , and

o thers ; it is also observable in the Baltic (Kiel) , and even in theDiatomaceous Oo zes o f the An tarctic Ocean as co llected by H. MM S

Challenger at a dep th o f fathoms . Dictyocha is, however,absen t from the Po lycystin ous earths o f Barbado s .

In Lompoc Dictyocha 1s represen ted by three species, Dictyochagraci lis .

Ehr . D . sp eculum Ehr .

,an d D . fibula Ehr . The first two

sp ecies are abun dan t , but the third is rather scarce . D . graci lis

Ehr is also presen t in o ther Californ ian dep osits, for in stan ce, inLos An geles ; but it is much less n umerous than i n Lomp o c .

The n umber Of sp ecies o f Dictyocha ,as described by Kutzin g ,

is about thirty -

.five Some of the fossil deposits, such as those of

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274 S ir N . Yermo lofiQ—Diatom Ear th i n“

Ca l iforn ia .

are so“

scarce that their presen ce may p erhaps be con sidered as

acciden tal Thus there are n o Aracli n oia'isci , so commo n in warmer

waters an d presen t even in the Los An geles depo sit ; o n ly o n e

Coscin ocl iscus p atellceformis Grev . has been foun d,

an d n o

Crasp edoclisci have'

o ccurred . On ly very few sp ecimen s of Cos

cin odiscus bullien s A . S. an d C. turg idus Battr .

,which are truly

southern fo rms, have been observed . There are in Lomp o c, it istrue

,man y forms belon gin g to the group o f Coscin ocl iscus marg in atus

Ehr . , but‘

the margin atus group can hardly be co n sidered as strictlysouthern

,this group bein g o ften met with

,as in the Mediterran ean

Sea . On the o ther han d,Lomp o c has very few represen tatives o f

“

the

genus Stephan op ywis, o r even of Me losira,sp ecies o f which are

commo n in warm waters . The genus Aotin ocyclus IS en tirely absen t ,o n the o ther han d,

o n e Actinocyclo id form,n amely Euoclia gibba

Bail .,is not o n ly abundan t 1n Lomp o c, but even domin atin g , just

as it is equally frequen t in the Moron deposit o f Spain . The

Actin op tychus forms in Lompoc are very p oo r ; there are man yspecimen s o f A . undulatus Ehr . , but they are n early all of extremelysmall size , n ot exceedin g some 30 micron s . The genus Astero lamp rais represen ted by two sp ecies, A . Greo i llei Wallisch . an d A . rotula

Grev . ,bo th very frequen t

,just as they are frequen t in the

Mediterran ean . The gen us Asterompkalus is also represen ted bytwo sp ecies, A . Moron en sis Battr .

, common in the Moron'

deposit,an d A . Hookeri Ehr .

,frequen t l n the An tarctic .

To gether with Dictyocha and Euodia ,the genus Coscin odiscus

domin ates i n Lomp oc . In deed, these three gen era share betweenthem n early the who le number o f organ isms in Lomp oc .

Of the n in e groups o f the genus Coscin odiscus, as tabulated byRattray in his Revision on ly five group s are represen ted inLompo c . These five groups are the In ordin ati , the Excen trici, theLin eati

,the Fasciculati

,an d the Radiati . The four o thers, the

Cestodisco idales,theElegan ti, the Elaborati, and the Co ccon e iformes,

are absen t .Of the five group s presen t, the domin atin g on e is that of the

Radiati . This i s made eviden t by the fo llowing statemen t of theresp ective numbers o f sp ecies : In ordin ati , 1 sp ecies ; Ex cen trici3 species ; Lin eati, 8 sp ecies ;

'

Fasci'

culati,13 species ; Radiati ,

25 sp ecies to tal , 50 sp ecies: Besides these fifty species there arein Lomp oc man y in termediate tran sition al forms between the

Excen trici an d the Lin eati, but their occurren ce is n ot remarkable,because such tran sition al series are also observable in Europeseas .

A cur ious fact con cern in g the Fasciculati group is the fo llowin gCoscin ocl iscus subti lis Ehr . so common in Europ ean seas, isp o o rly represen ted in Lompoc by very few an d small sp ecimen salso

, n o so - called derivatives o f C . subti lis,such as C. Kutzing i i

A . S. , C. Norman i Greg . an d C. Rotkii Grun .

,are to be found .

It would app ear as if the subt-ilis group had had n o go od opportun ity

Si r N . Yer n i o lofi —Di atom Earth i n Ca l iforn ia . 275

to evo lve in Lomp oc. On the o ther han d, an other - branch of thissame group , the odon tocliscus bran ch , developed well and safelyalo n g two o ther bran ch - lin es

,the odon tophorus bran ch and the

in terlin eatus bran ch .

It is remarkable that in the Ex cen trici group Lomp oc p ossessesthe species kn own under the n ame of Coscin ocl iscus

‘

decip ien s

Grun . ,common in the Baltic .

We n ow turn to the an alysis of the domin atin g Radiati group .

Its radiatus subgroup , with its derivative Coscin odiscus ArgusEhr . ,

is very n umerous . The oculis—iridis subgroup is also verynumerous with its large4sized derivative, Coscin ocliscus borealis Bail .Coscin odiscus cen tralis Ehr . is also numerou

js but, curiously en ough,

the clo sely allied C . con cin n u'

s W. Sm . and C . n obi lis Grun .

,commo n

in the Baltic an d the Mediterran ean , are totally absen t .The marg inatus subgroup with its numerous derivatives, as shown

in the app ended list, is fairly numerous,though , as has been stated,

this subgroup is already more or less tran sition al to southern forms .

There are two in terestin g facts to n o te in its occurren ce at Lomp o cin the first p lace there are man y specimen s o f the so—called C.

robustus, with exterior Sprin gs as described on p . 64 o f Rattray ’

s

Revision ”

,and p eculiar to the Californ ian San ta Mon ica dep osit .

In the secon d p lace there are

'

some Coscin odiscus forms closelyresemblin g tests o f n iclicula, a genus sometimes con sidered to

belon g to the Rhizop ods .

These fo rms'have co nvex valves with pun ctuate alveo les . The

pun ctae on the alveo les are very clear an d con sp icuous . It is justp o ssible that the forms men tion ed in the app ended list as C. bip artitus

Battr .

, or C . blandusA . S. may be tests o f Pyr idiculae, also p erhap sC . robustus var .fragi lis Battr . The sp ecimen s from Lomp o c classifiedas C. bip artitus are quite similar to the '

figures given by ProfessorDe Ton i 1n his work, An alisimicroscop ica di alcun i sagg i oli jitop lan ktonracco lti dalla R.N . Liguria,

but they have n o lobes, a circumstan cehardly to _

be con sidered as un exp ected, these i

lobe s bein g o f a n o n

siliceous comp osition an d therefore n ot able to withstan d the effectso f fo ssilization . On the o ther han d,

some of the forms in questionrather resemble - Pyxidicula

'

Mediterran ea Gru’

n .

, a fo rm n o t

un frequen t in the Mediterran ean Sea . The whole question is,however, as y et a subj ect o f controversy requirin g further elucidation .

A very curious fact in the Fasciculati group is exhibited in Lompocin con n exion with the sp ecies , C . curvatulus Ehr .

, C: radio latus

Ehr ., C. radiosus Grun . , C. cegin en sis A . S.

,an d C. n odulifer Jan .

All these sp ecies show somethin g like a distin ct n odul e,Whilst

their fasciculate structures are extremely alike,the .sp ecies p assin g

'

from on e to the o ther by mo st in sen sible gradation s .

The gen era Dictyocha,Euocl ia

, Coscin ocliscus, and Thalasswn ema

domin ate , “

and give to the dep o sit its characteristic facies “.

It hasundoubtedly a much mo re n o rthern facies than

,say ,the depo sit

from Los An geles, which con tain s man y more southern forms .

276 Si r N . Yermo lofi— Diatom Ear th i n Cal iforn ia .

The abun dan ce of the Dictyocha an d Euoc'

l ia is, indeed, the mo st

remarkable feature 1n the Lomp o c dep osit .As to the Radio laria,

the sp on ge sp icules, an d the Lithasterisci ,they are n ot by an y mean s n umerous and presen t n o peculiarities .

There are also n o calcareous remain s , such,for in stan ce , as the

p lates o f Ho lothurian s, so well kn own in the Barbados earth . Thisis also an imp ortan t fact, con firmin g the n orthern character o f theLompo c dep osit .

LIST OF . SILi oEous ORGANISMS IN THE Fo ssrL DEPOSIT o r

LoMPo c, SANTA BARBARA CO .

, CALIFORNIA .

I , DICTYOCHlDEJE .

DICTYOCHA .

graci lis Ehr. Abun dan t an d domin at~m

sp eczilum Ehr. Abun dan t.

fibula Ehr. Rare .

Ac'rrmscus .

S irius Ehr . Fre que n t .

II. DIATOMACEZE.

EUODIA .

g ibba Bail . Abun dan t an d domin atin g .

COSCINODISCUS .

(A ) INORDINATI .

turgidus Battr. Rare .

(B) CESTODISCOIDALES .

Non e .

Non e .

Non e .

(E) COCCONEIFORMES.

Non e .

(F) EX'

CENTRIC‘I .

excen tricus Ehr. Abun dan t.

decip i en s Grun . Frequen t .

min or Ehr . Fre que n t . (C) HETEROPORUS GROUP

heterop orus Ehr . Rare .

crassus BaiI Rare .

g igas Ehr. Frequen t .

diorama A . S. Fre que n t .

bu l l ien s A . S. Rare .

decrescen t Grun . Rare .

Tran sition al forms to the GroupLin e a-ti

Frequen t.

’

(G) LINEATI .

l in eatus Ehr . forma min or . Frequen t.

l in eatus Ehr . Freque n t .

l ep topus Grun . Fre que n t .

an guste- lin eatus

“

A . S . Freque n t

margin ato - lin eatus A . S . Freque n t.

bip artitus Battr. Without lobe s.

Fre que n t .

blandas A . S. Freque n t .

(H) FASCICULATI .

(a) s'

uBTILIs GROUP .

subti lis Ehr. Rare . Smal l p o or

sp eclmen s

symbo lop horus Grun . On e sp ecime nin n in e sl ide s .

odon tophorus Grun . Frequen t.

ocl on todiscus Grun . Freque n t.

i nterlin eatus -Battr. Not rare .

ext-ravagan s A . S. Not rare .

di -

visus Grun . Rare .

minutellus Battr. Rare .

(b) CURVATULUS GROUP .

curvatulus Grun . Freque n tn odu lifer Jan . Fre que n t.

wgin en sis A . S. Freque n t.

radio latus Ehr. Freque n t.radiosas Ehr . Fre que n t.

(I) RAD IATI .

(a) RAD IATUS GROUP .

radiatus Ehr. Fre que n t.

A rgus Ehr. Freque n t.

obscuras A . S. Rare .

(b) OCULUS - IRIDIS GROUP .

ocu lus - iridis Ehr. Fre que n t.

bo rea lis Ehr . Fre que n t.

a steromp ha lu s Ehr . Rathe r rare .

cen tra lis Ehr . Frequen t.

p erfo ratus Ehr. No t rare .

ap icu latus Ehr . Not ra

(d) FIMBRIATUS GRpUP .

fimbriatusCa liforn i caGrun . Frequen t.(e ) MARGINATUS GROUP .

marg in atus Ehr. Freque n t .

robustus Grev . Fre que nt .

robustus biscu lp tus Battr . Not rare .

robustus with “sprin g s Not rare .

Se e p . 64 Rattray Revision .

robustus fragi lis Battr. No t rare . A

Pyr idicu la

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REVIEWS.

VON BAU UND LEBEN DER TRILOBITEN . I . DAs SGHWIMMEN .

II . DER AUFENTHALT,AUF DEM BODEN . DER SCHUTZ . DIE

ERnAHRUNG . By RUDOLF RICHTER . Sen oken bergian a,i,

pp . 213—38 , with 8 text - figures, December, 19 19 . ii, pp . 23—4 3,

with 13 text - figures, February ,1920 .

N the n ew periodical Sen clcenbergian a ,issued by the Museum o f

the Sen cken berg Naturalists So ciety in Fran kfurt a . M.,Rudo lf

Richter has begun a series o f in terestin g pap ers o n the structurean d life of Trilobites Dr . Richter has been led to this by hisstudies o f Devo n ian trilobites, an d esp ecially of the curious forms

found at Gees n ea'

r Gero lstein an d develop ed with much skill byhimself and o thers at the Sen ckenberg Museum .

Structurally fitted for a life on the sea - bo ttom,the trilobites

frequen tly remain ed on the sea - flo or, where they crawled o n theo o ze or o n p lan ts , or rested

,either ro lled up or outstretched and

p erhap s hidden by a thin lay er o f sedimen t . On the o ther han d,

mo st,if n ot all , trilobites could swim by the aid of their man y car

like limbs . The smo o th Phacop s - Pro'

etus typ e , with its stro n gmuscular body , was the most agile . The spin y o r horn ed typ e ,represen ted by CJp hasp is Acidasp is, an d above all the extraordin ary Lichas armatus fromGees, was adapted for gen tlemovemen tand flo tation or balan cin g in still water . Whether creep in g or

swimmin g , when disturbed theyro l led up sudden ly ,an d if swimmin g

thus san k rap idly to the bottom . In the ro lled - up state the spin es,when presen t, are seen to surround the body .

When swimmin g the trilobites probably fed o n larvae an d o therminute o rgan isms . When creep in g they probably shovelled up thedecay in g fragments. Of plan ts and an imals

,bein g provided in man y

cases with shovels, ploughshares, or rakes . They did n ot, however,burrow deep ly in to the o o ze , but kep t o n or just below the surface .It will ‘be seen that Dr . Richter’s views do n ot en tirely agreewith tho se expressed by Walcott, Do llo ,

von Staff, and Beck,an d,

o thers who have sp eculated o n the subj ect . But they are maintain ed by in gen ious argumen ts based on material bo th n ew an d old .

F . A. B .

DOELTER’

s HANDBUCH DER MINERALCHEMIE .

WE have received from the publishers four in stalmen ts o f thiswork, which have appeared sin ce 19 14 . From particulars

given on the cover it app ears thatvo l . i , bo th halves Of vo l . ii, an dthe first half of vo l . iii are n ow complete . Of vol . iii there aren ow to han d parts v—vii . Part v in cludes a detailed descrip tio no f a large number o f arsen ic and an timo n y min erals , main ly byDr . H. Leitmeier, o f Vien n a,

an d Dr . Hen gle in , o f Karlsruhe ;part vi includes the min erals of bismuth an d van adium,

and a lon g

Revi ews— Man gan ese Or es .

d iscussion o f the chemistry and phy sics of water, by Dr . R . Kreman n ,

o f Graz , with title - page and in dex o f vo l . iii , first half part viicommen ces the secon d half o f vo l . iii with the min eralogy of lithium,

sodium , p o tassium,n ative copp er and copp er oxides , rubidium,

an d

s ilver,also chiefly written by Dr . Le itme ier .

We are glad that it has been foun d p o ssible to con tin ue publication o f this mo n umen tal wo rk

,which is o f the greatest value from

the amoun t o f detailed in fo rmatio n con tain ed in it, as well as for then umerous referen ces to the literature o f modern min eralo gy .

MANGANESE ORES . By A . H. CURTIS . Imp erial In stitute Mon ographs on Min eral Resources . pp . 118 . 19 19 . Price 39 . 6d. n et .

HIS is an Imperial In stitute publicatio n which reflects credito n the author

,who has prepared an in terestin g and useful

mo n ograph , as a result Of an exhaustive study o f all publishedin formation on the subj ect .The War fo cussed atten tion o n man gan ese o res, as the pri n cl pal

con sumers drew their supp lies from In dia, Caucasia,an d Brazil ,

which n ecessitated o cean tran sp o rt ; an d also because effo rts tofin d an eflicie n t substitute for mangan ese in the manufacture o fs teel were o n ly partly successful .No twithstan din g the high sellin g value o f the min eral in recen t

y ears few n ew dep osits have been discovered . In Brazil , wherethe price in cen tive was p erhap s greater than elsewhere , on ly o n e

large o re body was foun d,which even n ow is n ot producin g . In

In dia n o n ew developmen ts have taken p lace , but the ferrugin ousdep osits o f the Sin ai

'

Pen in sula,an d tho se’ of the Go ld Co ast , bo th

discovered shortly before the War, are n ow active producers .

The mo st strikin g developmen t In the‘ industry si n ce 19 14 to ok

place In the Un ited States,which no t o n ly in ten sive ly op erated its

o wn low grade deposits , but also man ufactured practically all its

man gan ese iro n alloys , which in pre-Wé’.r days had been largely

imp orted from Europ e , either in blast furnaces o r by electricreduction .

In chapter I the author deals with the o ccurren ce , character,an d uses of man gan ese . It should be men tio n ed that the largeBelgian imp o rts o f man gan ese ore prio r to 19 14 were prin cipallyused in Luxemburg an d German y . Further

,the high man gan ese

con ten t o f Caucasian min eral refers to the product of washin gp lan ts, which con stitutes two - thirds o f the to tal output , the run

o f min e bein g of in feriOr grade to the Brazilian an d In dian oreswhich are n o t dressed .

It is in terestin g to record that the in ability of the Caucasus and

Brazil_

to i n crease their output in pre -War y ears was almo st en tirelydue to the railways , on which the min eral was carried

,bein g. State

own ed and o p erated, although In Russia there has always been theadded disability due to labour un rest .

.280 Revi ews— Man gan ese Ores .

In chap ter II useful tables are given regardin g British imp o rtsan d ex pOrts o f man gan ese ore an d ferro -

,alloys an d all Empire o re

dep o sits are deseribo

ed ,the details regardin g the Indian depo sits

bein g obtain ed from the excellen t Geo logical Survey publication s .

It may-be men tio n ed that the lateritic dep osits have proved to be .

highly ferrugin ous in dep th , although in man y cases o f go od gradeat surface— suggestin g precip itation o f iron prior to man gan ese,It is un fo rtun ate that the comparison o f co sts o f production

o f Brazilian ,Russian

,an d In dian man gan ese ores is based on

figures published man y y ears ago'

. At the presen t time the costo f p lacin g the min eral at British p orts is probably the lowest for theGo ld ‘

Co ast an d Sin ai o res fo llowed by the Caucasian ,In dian

,an d

Brazilian supp ly , but con ditio n s may chan ge at an y time , invo lvin galteratio n In the order given .

Referrin g to the prop o sed man ufacture of ferro - man gan ese inIn dia

,it may be n o ted that the alloy was produced at

ti

the TataWo rks durin g the War

,an d in View o f the rap id developmen t o f the

In dian iron an d steel industry , it is probable that it wil l con tinueto produce its requiremen ts

'

o f ferro - alloys .

Men tio n is made o f the utilizatio n of man gan ese o re for the .

manufacture of p ig - iron con tain in g 2 p er cen t o f man gan ese , whichfacilitates the removal o f sulphur for basic steel manufacture . The

estimated quan tity so emp loy ed,however, viz . 50 p er cen t, is high

a more correct figure would be 10 to 20 p er cent, which, however,will be greater as the output o f basic steel in creases .

The South African dep o sits are n o t exten sive , but may bedevelop ed for use in the local steel industry ,

and the same willp ro bably Obtain with bo th the Can adian an d Australian o res .

The Go ld Co ast man gan ese ore dep o sits are imp ortan t, an d as

it is probable o thers will“ be discovered i n the same district, theCo lo n y should become In the future an imp ortan t source o f supp ly .

Successful dressin g o f the min eral , an d the app lication o fmechan icalp lan t for gettin g an d dressin g the ore , as well as improvemen t o fthe shipp in g facilities, are n ecessary to en sure a largely in creasedexp ort .In chap ter III the ore b- odies In foreign coun tries are described .

It IS in terestin g to n o te that the successful in stallatio n o f washin gp lan ts in the Caucasus to treat the screen in gs , amoun tin g oto severalmillion ton s

,accumulated sin ce min in g op eration s commen ced,

has

resulted in a higher -

grade product and pro lo n ged the life of thedep osit .No men tion is made o f the Covadon ga dep o sit in No rthern Spain ,

p robably because n o thin g has been -

published regardin g it in recen t'

y ears . Man gan ese and iron - o res o ccur as boulders , in a claymatrix restin g o n limeston e

,as the basemen t ro ck . The separation

o f the ore is effected mechan ically , and three qualities of min eralare produced

,Viz .

(a ) Man gan ese ore of the highest grade , almost free frompho sphorus .

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2 82 Revi ews— Or ig i n of the Iron Or es at K i run a .

American resources,actual and p o ten tial , but also a useful summary

o f foreign sources, accoun ts o f the tests for p o tash , and pro cesseso f extractio n

,and fin ally a very full biblio graphy (up to and in cludin g

1918) Of the who le subj ect .ARTHUR HOLMES .

ORIGIN o r THE IRON ORES AT KIRUNA . By R . A . DALY .

Veten skapliga o ch praktiska Undersokn in gar i Lapp land,Geo lo gy o f the Kirun a District, part v . pp . 31 , with 4 figures .

Stockho lm,19 15 .

THE magn etite o re - bodies of Kirun avaara - Luo ssavaara are in

some resp ects the fin est kn own examp les of the differen tiatio no f oxides from an ign eous magma,

an d there has n atural ly been a

go od deal o f discussion as to the mechan ism by which this has beenbrought . about . Some writers con sider the p orphyries asso ciatedwith the ores to be lava - flows

, but Daly favours the hyp o thesiso f in trusio n . Emphasis is p laced o n the sequen ce of ro ck - typ esan d

'

ou the chemi cal composition of the p orphyries as con firmatoryo f magmatic segregation and particularly of the theory o f

differen tiatio n in p lace . The ore - bodies are believed to be basicsegregatio n s from the Overly in g quartz - porphyry in trusion ,

the upp ermember of the comp osite lacco lith , accumulated at its base byg ravity ; while the so - called in clusion s foun d scatteredthroughout its who le thickn ess are also regarded as un its o f

differen tiation , and n ot xen ol iths, as formerly beli eved? A detailedstudy o f the forms of these masses favours this co n clusio n . Tho semasses scattered at higher levels are similar in compo sition to theo re—bed at the base

,an d are supp o sed to have crystallized after

the magma had become too viscous to allow them to sin k like thee arlier on es which formed the ore . An importan t p o in t is here raisedn amely ,

- that sin ce n o on e disputes that Sin gle crystals, say o f

magn etite, in a magma are formed by differen tiation ,that is by

aggregatio n o f mo lecules from the so lution ,there is n o reason why

compoun d masses o f greater size should n o t have been fo rmed inan exactly an alogous man n er

,an d it is illogical to draw an y

arbitrary lin e between such un its o f vary in g size by assumin g thatthe larger on es must be xen o liths .

THE AMISK - ATHAPAPUSKOW LAKE DISTRICT . By E . L . BRUCE .

Can ada,Departmen t of Min es, Geo lo gical Survey Memo ir 105 .

pp . iii 9 1,with 7 p lates, 4 figures, an d a co loured map .

Ottawa,19 18 .

THIS area lies on the boun dary o f Man itoba and Saskatchewan ,

o n the divide between three great rivers , the Churchill ,Nelson , an d Saskatchewan . It forms part o f the bo rder o f theCan adian shield, about half bein g o ccup ied by pre - Cambrian rocksand half by. Ordovi cian do lomites . The an cien t rocks are divided

Rep orts at Proceedi n gs The Roya l So ci ety .

in to three series, the Amisk series of vo lcan ic ro cks at the base,

fo llowed by the Kisseyn ew gn eisses ; above these are the Lower andUpp erMissi series , probably separated by an un con fo rmity ,

and theseare cut by gn eisso se gran ite . The main in terest is eco n omic, themin erals in cludin g go ld- quartz vein s and chalcopyrite - sphaleriterep lacemen ts, bo th believed to be gen etically related to the gran itebatho liths .

ON THE ORIGIN OF THE KUROKO OF THE . KOSAKA COPPER MINE ,

NORTHERN JAPAN . By R . OHASHI . Journ al of the AkitaMin in g Co llege , 1920 . pp . 11—18 , with 2 figures an d

‘

2 p lates .

Akita,1920 .

KUROKO is a den se black ore c on sistin g o f sphalerite , galen a ,

and bary tes, usually with accessory pyrite, chalcopyrite ,

an d

quartz . Its fo rmation has been attributed by most writers to

metasomatism,

'

but this exp lan ati on p resen ts certain difficulties,e sp ecially from the absen ce o f an y Sign o f '

chemically actives ubstan ces . The author

,therefore

,sup p o rts the theory o f Fukuchi

.and Tsujimo to , that these depo sits are masses o f sin ter deposited on

the flo or o f the sea by ho t sprmgs , con temp oran eously with theformation o f the clay - beds in which they are n ow foun d the Sprmgs

were con n ected with the erup tion o f the i n terbedded rhy o lites .

REPORTS AND ; PROCEEDINGS.

THE ROYAL SOCIETY .

Ap ri l 29 , 1920 .

— Sir J 3. Thomso n , O .M.,Presiden t

,in the chair .

The Irish Eskers . By Professor J . W. Grego ry , F.R .S

Eskers are ban ks o f san d and gravel, typically o ccurrin g as ridgeson the cen tral p lain o f Ireland,

where they were dep osited duringthe recessio n of the ice at the clo se o f the Glacial p eriod . They havebeen gen erally attributed to dep ositio n alo n g glacial rivers , likeSwedish osar . Their structure an d comp osition in dicate that themost imp ortan t Irish eskers were formed alo n g the margin o f therecedin g ice - sheets“ by flo ods of water

, _d

'

ue to the meltin g o f the icIrish eskers formed alon g glacial rivers are relatively small an d

e xcep tion al . The accumulation o f the materials in to ridges, an d theirrestriction between about 150 and 300 feet above sea - level , are

attributed to the formation o f the eskers where the ice en tered in to:a sheet of water

,which was probably the sea ,

Sin ce marin e fossilsare widely distributed in the adjacen t drifts, an d there are n o

e mban kmen ts to main tain glacial lakes at the required level .It is prop o sed that the term esker should be co n tin ued fo r Irish

ridges an d mounds of san d an d gravel, but that in glacial geo logythe term osar Should be used for ridges fo rmed alo n g the glacialrivers

, and [fame used for ridges depo sited alon g the margin of an

ice sheet .

284 Repor ts (fa Pr oceedi n gs— Geo log i sts

’

A ssociati on .

GEOLOGISTS’

ASSOCIATION — May 7, 1920 .

Imp lemen ts from Plateau Brick - earth at Ip swich .

Regin ald A . Smith , F.S.A .

On the east side o f Ip swich , immediately east'

o f Derby RoadStation , exten sive excavation s for brick - earth have brought to lighta fin e series o f flin t imp lemen ts n ow in Miss Layard s co llection at

'

Christchurch. Man sion,and described in Journ R . An thro p . In st . ,

xxxiii,41 ; xxxiv , 306 xxxvi, 233. With the assistan ce of the

”

PercySladen Trust, a large pit was dug un der careful sup ervision in 1914,an d the o ccurren ce o f wo rked Hin ts at differen t levels verified .

There had been 2 feet of con to rted gravel above an d a Slop in g ban ko f gravel below, a wedge of brick - earth

,suggestin g the former

presen ce o f a river, which can ,indeed, be deduced from the levels .

Clemen t Reid recogn ized Boulder clay at the bo ttom’

of a borin g ,at 27 feet, and the geo logy of the site has been studied by Pro fessorBo swell (Pro c . Geo l . Asso c .

,x xv but a comparison with the

Cadd‘

in gto n Series (Archeo logia ,lxvii

,49 ) stren gthen s the argumen t

fo r p lateau dep o sits late in the pal’

eeo litl nc Drift p eriod,an d reop en s

the question of their relation to the Terrace gravels . The site is onan iso lated p art o f the p lateau between the main an d lateral valley so f the Gipp in g an d Deben

,an d is 120 feet above sea - level , the

Boulder - clay termin atin g in an east - and- west lin e 1 mile tothe n orth .

OPTICAL SOCIETY .

~—Ap ?’i l 15 , 1920 .

The Ro ck Crystal o f Brazil . ” By R . R . Walls,M.A . ,

B .Sc .

The author describes the o ccurren ce in the field of the clear varietyo f quartz kn own as ro ck cry stal . Although the high p lateau o f S.E .

Brazil 1s essen tially a gran ite an d gn ei ss coun try ,the ro ck crystal .

is n o t foun d In the gran ite itself, but In a series of bedded quartzi tesoverly in g the gran ite . Clear ro ck crystals o ccur o n ly in the spacesbetween the beddin g p lan es, but the p lan es of the crystals can betraced downwards fo r several feet acro ss the beddin g plan es . Hugecrystals have thus been formed,

an d the autho r illustrated on e

weighin g 13 cwt . Clear crystal an d co loured varieties— amethyst ,smoky ,

“

and cairn gorm— were foun d acco rdin g to the purity or

impurity o f the origin al san dston e .The san dston e had eviden tly been stewed up and metamor

pho sed in to ‘

cry stal ,but what was the cause of this Is n o t clear .

In trusive gran ite suggested itself, but there was n o Sign o f it an ywhere . The crystal was foun d o ften in the n eighbourho od of

sericitic schist,which when worked out seemed to o ccupy a fissure

in the ho rizo n tally bedded san dston es and quartzites . The sericiticschist co n tain ed diamonds , but was very eviden tly n ot an alluvialdep o sit . It app eared,

therefore,as if this schist was the highly “

metamo rphosed remai n s o f a vo lcan ic p ip e similar to the diamon dbearin g p i p es o f South Africa ,

an d that its in trusio n in to the san dston es an d quartzites had metamorpho sed the latter in to ‘‘

cry stal

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286 Corresp on den ce W. T. Orol .

p erusal of our recen t pap er provides the mo st co n vin cin g reply ;an d sin ce our method o f attackin g the problem differs so widely fromthat adop ted by Mr . Lamplugh , we feel that a con troversy would befruitless .

F. L . KITCHIN .

‘

J . PRINGLE .

LONDON.

May 1 2 , 1 920 .

SIR,— Although the subj ect o f the Bourn emouth Chin es is

"

chiefly o f ,lo cal in terest,as Mr . Bury in his pap er in the February

n umber has referred several times to my views,may I be permitted

a few words in rep lyMr . Bury

’

s pap er chiefly deals with the seaward asp ect of thechin es , an d curiously he omitsmen tion o f the on e determin in g featurewhich is commo n to all the chin es

,and more than an y thin g else

is resp o n sible for their form,dep th , con tour o f sides

,an d an gle o f

reces’ sion in cliff- face . This is the po sition ,thickn ess, an d n umber

of the clay - beds which o ccur in the friable san dy strata from whichthe chin es have been carved by the action o f lan d water . In thirtyy ears residen ce in the town I have more an d more been struckby this, and led to attribute less and les s to sea action at the cliff - face .If an y visito r will examin e the shorter and lesser chin es, such

as Hon eycombe Chin e , east of Boscombe pier which is n ot

men tion ed by Mr . Bury— also Middle Chin e

,Little Durley Chin e ,

an d Can ford Cliff Chin e , they will readily admit the in fluence ofthis facto r . That the larger chin es— Bran ksome

,Bourn e Valley ,

an d the mouth o f the Bo urn e,an d probably Bo scOmbe Chin e— are

remain s o f the o ld So len t River drain age system can n o t be doubted .

But all have been deep en ed an d widen ed sin ce the sea in vadedBourn emouth Bay ,

by the action o f lan d streams causin g co n stan twashin g out of san d and slippin g o f clay - beds as they were uncovered .

I have n ever thought it n ecessary to invite the aid o f glaciation or

a hyp o thetical co ombe - ro ck to accoun t for what is o therwiseeasily exp lain ed . At the clo se o f the Glacial period an d the begin n in go f Neo lithic times, flo ods from the meltin g o f ice - sheets furthern orth first eroded the surface an d then dep osited the sheet of plateaugravel which we fin d coverin g the strata aroun d Bourn emouthto—day . This o ccurred when the Bourn e Valley was half its presen tdep th . The p lateau gravel is foun d in p laces down what Mr . Burycon siders the o ld valley level in Bran ksome an d Alum Chin es . Thepresen t chin e level has been formed since the clo se of the Glacialp eriod . The So len t River system had been destroy ed lon g beforeth1s almo st immediately o n the sea breakin g through the ran ge ofchalk hills which soun din gs Show . muSt have occurred n o t far easto f Ballard Down ,

the p eriod bein g either durin g o r just before theraised beaches were formed .

Corresp on den ce— G. M. Davi es .

With regard to the an gle of the cliff - slope, my o bservation sen tirely confirm Mr . Carus Wilson ’

s op in ion that the cliffs are

steep er n ow than formerly.

W. T . ORD ,F.G.S.

BRAMBER ,

18 LITTLEDOWN ROAD ,

BOURNEMOUTH , E .

NOMENCLATURE OF THE HEAVY LIQUIDS .

SIR,

— In dealin g with laborato ry methods fo r the separation o f'

min erals o f differen t den sities,some writers sp eak o fKlein ’

s so lutio n,

Braun s’

so lutio n ,Rohrbach ’s so lution

,an d So n stadt

’

s (or Thoulet’

s )so lution . Others use the chemical n ames of the fluids— c admiumborotimgstate,methy len e iodide , etc . This double n omen clatureis con fusin g an d a tax o n the memory ,

a nd it would be well if on eo r o ther set o f n ames were adhered to an d the o ther aban don ed .

In the case o f the do uble iodide so lution s, the person al n ame hasthe advan tage o f brevity over the chemical . The desire to givehon our where hon our is

“

due may also in clin e some workers to itsuse . But in this resp ect we are far from con sisten t . Bromoform,

the mo st gen erally useful of all the heavy liquids, might with justicebe called Schro eder van der Ko lk’s liquid . Moreover

,Professor

Braun s was n o t the discoverer o f methy len e iodide, he was merelythe first to describe its app lication to min eralogy an d some o f theo ther authors have even Slighter ‘

claims to the l iquids with whichtheir n ames are asso ciated .

The chief obj ection to the perso n al n ame is that it has n o in trin sICrelatio n to the fluid an d suggests n o n e of its prop erties . Thechemical n ame, o n the o ther han d, sp ecifies the compo sition of thefluid referred to , and so recalls to min d its physical prop erties . Thechemists will n ot be p ersuaded to c all methy len e iodide Braun s’so lutio n , though they are

'

n o t free from a similar practice (e . g .

Fehlin g ’s so lutio n , Co n dy’

s fluid,It would be a go od thin g if

min eralogists would avo id the n eedless duplication of n ames an d

always use the chemical in stead o f the person al n ames for the

heavy liquids .

G. M. DAVIES .

1 7 ELMWOOD ROAD , CROYDON .

May 4 , 1 920 .

OBITUARY.

Walte r R . Bill in gs.

THROUGH the death o f Mr. Walter R . Billin gs, Can ada has lo st acitizen of un usual attainmen ts . His death o ccurred at his home inOttawa on March I

,in his 71st y ear . Mr . Billin gs was an architect

by pro fession and a palmon to lo gist by n atural taste and in clin ation .

288 Obi tuary Wa lter R. Bi l lin g s .

Although palaeo n to logy was an avocation that he actively fo lloweddurin g .o n ly a p o rtion of his mature life , the work which he has leftforms a substan tial an d Valuable contribution to the scien ce .The an cestry ofWalter R . Billin gs o n the patern al side was rather

comp lex , in cludin g Welsh , En glish, Sco tch , an d Irish elemen ts .

His gran dfather was born in Massachusetts , his grandmother in .

Newb

York . Braddish Billin gs, gran dfather o f Walter,was the first

white settler in Ottawa,

‘

Vvhere he came when there was n o thin g tosuggest the future city ,

which develop ed later over a part o f theacre tract o f lan d which he acquired . Walter R . Billin gswas

'

a n ephew o f Elkan ah Billin gs , the distin guished first palaeon to logisto f the Can adian Geo logical Survey . To palaeon to lo gists the deatho f the n ephew will recall the birthday o f paleeon to logical scien ce inCanada , which may be said to co in cide with the publication o f

Elkan ah Billin gs ’ first pap er o n the Cy stidea . To this able an dr emarkable man Can adian n aturalists owe a debt o f gratitude forstartin g at his own exp en se the first magazin e devo ted to NaturalHisto ry published in Can ada .

With such a sp on sor in E . Billin gs, it is small won der thatpalaeo n to logy made a stron g app eal to the subject of this sketch .

In sp ired n o doubt by the work o f his un cle,Walter R . Billin gs

became an arden t co llector o f fo ssils . That his co llection s came toin clude man y rare and beautifully preserved sp ecimen s is sufficien tlyattested by the published referen ces to them o f fo reign palaeon tol ogists . Dr . Bather

,o f the British Museum

,has referred to man y o f

the sp ecIeS co llected by W. R . Billin gs . His gen erous spirit led him'

to loan his co llection s freely to those prepared to~make use o f them,

an d some o f his rarest sp ecimen s were presen ted to the BritishMuseum .

His own published studieswere con fin ed chiefly to the Crin oidea ,

an d he is kn own to studen ts o f this group fo r his valuable wo rk Onthe Tren to n crin o idal faun a of On tario .

Man y imp ortan t additio n s to the kn owledge o f the Crin o idea haveb een made by Dr . Bather from studies of material co llected byW. R . Billin gs . He was always ready to p lace at the disp o sal ofVisitin g geo logists his in timate kn owledge o f co llectin g lo calitiesin the Ottawa district . The valuable cOlle ctio n o f fo ssils left by himhas been presen ted to the Can adian Geo logical Survey by his Sisters,in accordan ce with his wishes .

He was a man_

o f broad in terests an d for man y y ears to ok a keenin terest In athletics

,esp ecially In the water sp o rts fo r which Ottawa

i s n o ted . Man y o f his vacation s were sp en t on his luxuriouslyfurn ished house boat . He represen ted a typ e of man far to o rarein Can ada

,but mo re commo n i n En glan d, .who fin ds the time an d

Shows the ability to make worthy con tributio n s to pure scien cewhile fo llowin g a profession In n o way allied to the scien ce in whichhe delves .

E. M. KINDLE .

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1 9 1 7 an d 1 9 19 .

GROVES (J. ) AND - BULLOGK -.WEBSTER (G . R ) . British Charo phyta .

Vo lume 1, Nite l leae . pp . x iv +3142 .

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COURSE OF FOUR ADVANCED LECTURES on Divers

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Pro fe sseur de Min éralo g ie au Muséum Nation al d’Hi sto ire Naturel le

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JULY, 19 20 .

EDITORIAL NOTES

ORIGINAL ARTICLES .

Diffe re n tiatio n an d Ore - dep osits .

By R . H . RASTALL

No te s o n the Faun a o f the Lower

Devo n ian Beds o f Torquay .

Part I . By F . R . COWPER REED .

Horn bl en dite at Vavas‘

our Min e ,Can tl ey , Quebe c . By J. STANS

On an Exp o sure o f San ds an d

Grave l s con tain in g Marin e She l lsat Easin gton , Co . Durham . ByD .WOOLAOOTT

On Jurassic Ammon ite s from East

Africa , co l le cted by Pro f . J . W.

_

ARTIOLES (con tin ued) .Gregory . By L . F. SPATH .

In ve stigation o f the Mechan icalCon stitution o f Lo o se Are n ace ous

Sedimen ts by the method o f

Elutriation . By H . A .

REVIEWS .

Geo logy o i the Yan gtse Estuarybe lowWuhu

Diagn o sticCharacteristics o fMarin e

The Min eral Dep osits o f SouthSp ecial Rep orts on the Min eralRe sources o f Gre at Britain

Earthquake s in Oregon .

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321

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ORIGINAL ARTICLES.

Diffe re n tiatio n an d Ore - de p o sits.

By R . H. RASTALL,M.A ., Un iversity Lecturer in Econ omic

Geo logy , Cambridge .

AT the presen t time most min in g geo logists app ear to be in gen eralagreemen t on the prin cip le that primary ore

- dep o sits are derivedfrom ign eous magmas . Furthermore

,it is n ow almo st un iversally

recogn ized that the segregation and con cen tration o f the metalsan d their compoun ds in to payable o re—dep o sits is but part of a

larger an d more fun damen tal problem,

'

n ame ly , the differen tiationof the ign eous ro cks

,a problem which has exercised the ingen uity

o f petro logists for man y y'ears past an d is still by n o mean s so lved .

Un fortun ately most o f the speculation s an d theories put forward inexp lan ation o f these phen omen a are in the main founded on factsan d in feren ces derived from the study of the silicates comparativelyfewp etro logists have taken in to accoun t the behaviour of the oxidican d sulphidic compounds of the useful metals, which are common lyregarded in the light o f rare an d acciden tal con stituen ts of themagma, rather than as havin g an y particular bearin g on the p o in tat issue . The most n o table excep tion to this gen eral statemen t isVo gt,1 who se work o n slags an d o re - dep o sits is o f an ep och - makin gcharacter from the theoretical po in t o f view,

as well as o f immen sepractical imp ortan ce in smeltin g and blast—furn ace practice . However

,within the last few y ears great atten tio n has been devoted by

min in g geo logists to the subj ect o f the gen esis of ore - dep osits,main ly because o f its bearin g on the question o f p ersisten ce in depthor the replacemen t at lower levels of on e ore by an o ther, such as iskn own to occur in certain cases . Itmay be suggested, therefore, thatthe time has n ow come when it may be p ossible to attempt to com

bin e the facts hitherto discovered alon g differen t lin es o f researchin to a coheren t who le .We have stated that most min in g geo logists are in agreemen t as

to the derivation o f primary ores from magmas,but there is stilla go od deal of differen ce of op in ion as to the n ature of the processesby which this derivation or segregation is brought about . The mo stun fortun ate feature of the who le problem is that investigation byexp erimen t is almo st, if n ot quite, imp ossible “

; it is un likely thatwe shall ever be able to realize in our laboratories the temperaturesand pressures that must prevail at even small 'dep ths in the earth’scrust

,small

,that is

,by comparison with the radius, though large

when expressed in feet or miles . It is n ecessary , therefore, to fallback on in direct eviden ce an d argumen ts from an alogy , and

’ it mustbe admitted frankly that extrapo lation is always a dan gerousprocess .

1 Studier over S lagger , Stockholm ,1 884 Die Si likatschmélzltjsun gen ,

Kristian ia, 1903- 4 .

R. I f. Rasta lZ—Difiéren ti aiion an d Ore - dep osits . 291

As we have already stated, much differen ce o f opin ion has prevailedan d still con tinues to p revail amon g p etro logists as to the realnature o f the pro cesses by which differen tiation of rock - magmas

has been brought about . From our po in t of view the elucidation “

o f

the exact mechan ism o f the p ro cesses invo lved is o f less importan cethan a clear recogn itio n of the fact that differen tiation has takenplace . Here it is n ecessary to con sider fo r a momen t what we reallymean by differen tiation . As a matter o f fact two distin ct ideas. are

here invo lved,n amely , (a) the production o f heterogen eity within

the limits o f a sin gle con tinuous mass,and (b) the splittin g o f an

o rigin ally homogen eous mass in to two or mo re separate and discreteportion s .

1 It may be regarded as'

certain that bo th of these effectshave been produced in differen t ways in differen t cases .

Theories o f differen tiation may be divided in to three prin cipalcatego ries, as fo llows : (1 ) differen tiation by sinkin g of crystals ina liquid magma, (2) differen tiation by diffusion of mo lecules inso lution to the margin al p ortions o f a co o lin g an d crystallizin gmass, (3) separation of a so lution in to two immiscible fraction s as

temperature falls . Itwill be observed that 1 ) an d (2) are very similar,while (3) is essen tially differen t, in that its o ccurren ce may be lon gan teceden t to so lidification . Hen ce we see that there are reallytwo typ es o f differen tiation

,on e dep endin g on so lidificatio n

(crystallization ) , the o ther bein g en tirely in dep en den t o f it . An o therpo in t which has led to much discussion is this, whether an y formo f differen tiation is dependen t o n assimilation o f rock from thewalls o f the magma - basin . This hyp o thesis o f the production o f

heterogen eous differen tiation products by absorp tion o f materialactin g as a flux has been largely develop ed by Lo ewin son - Lessing 2and by Daly .

3 Bo th '

o f these authors con sider that there were twoprimary magmas, gran itic an d basaltic respectively ,

”

an dDaly regardsthe alkalin e ro cks, the sy en ites and trachytes an d their con gen ers,as formed by differen tiation from the primary gran itic magma afterassimi lation of limeston e . To this pro cess he applies the n amesyn texis . Neither author has apparen tly co n sidered the origin o f

the two primary magmas from a still earlier common source , a

po ssibility which must also be taken in to accoun t in a completetheorItWill , I think, be gen erally agreed that in a case of this kind thebest method of pro cedure is to start from a foun dation of knownfacts and work back to the unkn own . Let us, therefore, begin with

1 It has bee n we l l poin ted out by Daly that the formation of cry stals o f

differen t min erals , such as quartz , fe lspar , andmica , from a magmatic so lution

is in real ity a pro ce ss o f differen tiation in its simplest form .' Each sin g le

crystal is in such a case a un i t o f difi eren tiation . This po in t has been ign oredby most p etro logists . It ,is in real ity on ly the mon o - min eral ic rocks whichcan be regarded as strictly homoge n e ous , an d - these are very rare .

2 Lo ewin son - Lessin g , GEOL . MAG . , 1 9 1 1 , p . 248 .

Daly , Ign eous Rocks an d their Origin , NewYork, 1914 .

292 R. H. Rasta l’

l—4 Difier en tiati on an d'

Or e - d-

ep osi'

is .

a simple case on which iwe p o ssess some so lid in formation as a basis .

In the smeltin g '

o f metals from their ores the metal sinks to thebo ttom,

while the n on - metallic impurities and fluxes rise to the topas a slag . This is .n ot merely sin kin g by gravity ,

but depen ds on

the prin ciple o f immiscible liquids . Vogt has shown that at an y giventemperature above the freezin g p o in t o f bo th liquids there IS a certainamoun t of mutual so lution ,

the metal disso lvin g some o f the slagand the slag disso lvin g some of the metal, and that the so lubilityin each fraction in creases with the temperature . Itmay be in ferred,therefore

,that at a certain .very high temp erature there would be

complete mutual so lubility in an y proportion s . Such temperatureshave n ot, however, been attain ed in ordin ary furn ace practice .Now

,if we invert the argumen t and imagin e a rock - magma con sistin g

o f mutually disso lved silicates an d sulphides at a very hi ghtemperature, but con stantly losin g heat by conduction ,

a time willcome when the magma must begin to separate into two lay ers, o n erich in silicates, the o ther in sul phides

,and the sul phide portion bein g

the heavier will o ccupy a lower p osition ,thus leadin g to a segregation

of sulphides at the bo ttom o f the magma basin . In o ther in stan cesthemetals may be presen t as ox ides or fluorides, in stead o f sulphides,but the result will be the same, n amely , a stratification Of the magma .

It is possible that In some cases the metallic compounds may be

lighter than the silicates, and therefore form the upp er lay er . but

the prin cipl e 15 the same . The amoun t of on e of the con stituen tspresen t in the ro ck formed from the o ther fraction when so lidified,e .g . the amoun t o f sulphide in n ormal gabbro or n orite,wi ll depend Onthe solubility of the sulphide in the gabbro magma at its temperatureof con so lidation . Therefore

,it would app ear that there must be

a limi t to the p ercen tage of primary ore that can occur even lydissemin ated throughout a rock mass . If the amoun t of metal wasorigin ally l n excess o f this proportion it would n ecessarily form a

richer segregation lay er at the bo ttom . The forego in g statemen trepresen ts what must o ccur in ' the simplest possible case . Whenthe metals fo rm vo latile compounds the relation s are more complex ,as will be exp lain ed in a later section .

The argumen t may n ow be carried o n e stage further back . It hasbeen suggested by certain leadin g petro logists that some o f thephen omen a o f differen tiation ,

as shown by the distribution ofvary in gro ck - typ es in defin ite areas, can be explain ed o n the supposition of

limited,miscibility between magmas of differen t silica p ercen tage ,

or in o ther words between acid an d basic magmas .

‘The gen eralidea is that with a fallin g temperature the silicates of magn es1a,iron ,

and lime become less so luble l n the silicates o f alumin a, p o tash ,and .soda, and a separation occurs, the silica dividin g itself In theproper ratio between the two fractions, thus producin g two partialmagmas . Themagn esia,

iron ,and lime require less silica for comp lete

n ormal saturati o n than the alumin a, po tash , an d soda,hen ce on e

fraction 18 a basic magma, the other an acid on e,in the ordin ary

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294 R . H. Rasta ll - Difiemn tiati on an d Or e - dep osi ts .

the . sp littin g is a,matter of min or imp ortan ce the facts of n ature

an d the distributio n o f the vary in g ro ck - typ es are in themselvessufficien t pro o f

'

that somethin g o f the sort must have o ccurred,

however it was brought about . It is un n ecessary here to con sider indetail the mean s by which ,

the differen tial fraction -

s have becomeiso lated in separate basin s within the earth’s crust, o r poured out

as extrusion s at the surface (lava - flows) . This part o f the subj ecthas been discussed in detail by man y writers . What we are main lycon cern ed with n ow is the ultimate fate o f the metallic con stituen tsthat were '

disso lved in the differen tiated partial magmas beforeso lidificatio n began .

Let us first con sider 'the case of a gran ite magma,such as the

gran ites of Cornwall, in to which has been carried durin g partitiona con siderable prop ortion o f tin

,tun gsten ,

copp er, arsen ic,lead,

zin c,and other metals

,together with fluorin e

,bo ron ,

an dwater, inaddition to the con stituen ts of the silicates, felspar, an dmica, togetherwith an excess of silica . The micas crystallize first

,fo llowed by the

felspars,in the order of their freezing -

p o in ts these are fo llowed byquartz

,the metallic con stituen ts, together with the fluorin e, boron ,

and'water

, all ten din g to con cen trate in the last un fro zen residue ,presumably in the middle an d lower parts of the mass

,which are the

ho ttest . All these probably remain un so lidified to a comparativelylow temperature, p e‘rhap

’

s below a visible red heat, although it mustbe remembered that pressure raises freezin g - po in ts . However, thealready so lidified mass is still co o lin g an d therefore shrinkin g invo lume . Con sequen tly cracks must be developed to relieve thestrain . These cracks apparen tly often exten ded radially in to thesurroundin g ro cks . Alon g these cracks the still fluid material fromthe in terior must sho ot out, un der high pressure due to sup erheatedwater

,fillin g them with the residual magmaticmaterial , an d in the

pro cess also brin gin g about far- reachin g chemical chan ges in thewall - ro ck o f the fissures . Thus we accoun t for the p egmatites ,ap lites, an d greisen s, so commo n in an d aroun d man y highlyIn in eralized gran ites . In some cases also the escap e of fluids from a

the co o lingmagma has been facilitated by earthmovemen ts, inducingfissure systems dep en den t on the direction o f the se “

movemen ts,rather than merely radial . Sometimes the active chemical agen tsderived from the magma brin g about the mo st far- reachin g changes,such as tourmalin ization ,

in the gran ite itself, the extreme casebein g schorl - rock

,where everythin g has been con verted to quartz

an d tourmalin e ; in o ther in stan ces topaz is very abun dan t . 4

But the p o in t of immediate in terest is the fate of the metalliccomp oun ds in the magma . We know from in co n trovertible eviden cethat the dep osition of the o res be lon gs to the later stages o fmagmaticcodli'n g . There is n o n eed to labour this p o in t . It may be takenas demon strated that the dep o sition of the o res is subsequen t tothe

'

crystallization o f the main mass,an d m an y o f them are

found in the pegmatites and i greisen s, havin g been depo sited

R . H. Rasta l l— Difieren tiati on an d Or e—dep osi ts . 295

con temp oran eously with their formation . But the question of thequartz—vein s in the stricter sen se o f the word requires a little moredetailed con sideration . In the first p lace it should be rememberedthat the pro cesses here un der review take place at temperaturesabove the critical p o in t of water, 365 degrees C. ,

and therefore theusual distin ction between liquid and vapour is then n on - existen t .For this reason the term fluid has been used throughout thisdiscussion . We do n ot kn ow the temp eratures at which the n ormalquartz - felspar p egmatites actually so lidify , but we do kn ow thatthey o ften con tain ore - min erals . Some ore - min erals therefore format fairly high‘temperatures . There is n ow abun dan t eviden ce fromobservation thatman y true pegmatites pass.by in sen sible tran sition s,by diminution of felspar, mica, etc .

, an d correspondin g in creaseof quartz , in to quartz - vein s in the ordin ary sen se o f the term,

eitherwith or without metallic min erals

,In some cases a vein may be

a pegmatite within the gran ite, passin g gradually in to a quartzvein in the sedimen ts . It is clear

,therefore, that there is n o real

distin ction between these two types .

It is n ecessary n ext to in quire why some of the con stituen ts o f theorigin al magma shoul d remain liquid so much lon ger, i . s . to a lowertemperature than the main mass . The an swer to this question isto be found in a con sideration o f the effect o f the more vo latilesubstan ces con tain ed in the o rigin al magma . As this graduallyso lidifies it is obvious that all the substan ces o f lowest freezin gp o in t must ten d to con cen trate in the last fluid residue . Amon gthese substan ces are to be reckon ed compoun ds of the useful metals .

These probably exist in the magma as fluorides, borides, sulphides,an d hydrates . The presen ce o f superheated water here is doubtlesso f first- class importan ce , as shown by Arrhen ius .

1 For example ,tun gsten fluoride is kn own to be a

, gas at the ordinary temperature ,while tin fluoride bo ils at 705 degrees C.

2 As the temp erature fallsthese elemen ts group themselves differen tly and even tually crystallizeout as metallic min erals, together With the silica o f the residualmagma

,which crystallizes as o n e of the two forms of quartz . The

last fraction of all is a pure , or n early pure , so lution of silica, whichforms the simp le quartz - vein s often foun d far from the margin o f

an y visible in trusion . It appears clear, therefore, that there is n o

real lin e of demarcation between the so - called pegmatitic and

hydro thermal min eral depo sits .

When several metals are presen t in on e individual magma ,as is

usually the case, each will form a compoun d havin g its own so lidifica

tion temp erature and therefore capable o f travellin g on ly as far as

the correspondin g t emperature exten ds in to the surroundin g rockswe shall therefore have a series of ore - zon es around the in trusion ,

as is so well seen in Cornwall .1 Zur Physik de s Vulkan ismus Ge o l . Foren . Forh . , vol . xxn , 1900 ,

395 . Abstract in GEOL . MAG . , 1 907 , p . 1 73.

:2 Roscoe 8;Schorlemmer, Treatise on Chemistrymoh n , _

19 13, pp . 861 , 1095 .

296 R . H. Ruste d —Dif feren tiati on an d Ore - dep osi ts .

Thus it is obvious that when a partial magma has reached its fin alrestin g - place and i s there crystallizin g , there must be a more or lesscomplete separation o fmetallic co n stituen ts . This takes place Intwo stages, .first a con centration in the last residue of the crystallizin gmagma, and then a tran slation alo n g with this residue in to dykes,ve i n s, and lodes .

This process is best .kn own and the relation s are most clear In thecase o f the acid magmas, but the same thin g occurs in the case o fbasic in trusion s, with on e importan t difleren de . The basic magma

is less rich l n vo latile con stituen ts, fluorin e and boron be l n g absen t ,and for some reason n ot y et understood water is apparen tly less

.abundan t . Hen ce there IS less tenden cy for the metals to segregatein to dykes and

i

vein s . More common ly they remain more or lesseven ly dissemin ated like chromium and platinum,

o r sink to thebottom like the n ickeliferous sulphides . It is worth n otin g thatchromium and platinum are mo st abundan t in the ultrabasicperido tites, which are themselves to be regarded as differen tiatesof the larger basic magmas .

We are thus . led to recogn ize two distin ct typ es o f ore - dep o sitso f direct magmatic origin ,

formed by differen tiation ,n amely , the

segregation s within the mass o f the magma itself, such as then ickelifero us sulphides o f Sudbury o r the i ron - ores of Kirun avaara,where . there has been on ly separation by sinkin g within the basin ,

and secon dly ,the fissure dep osits, dy ,

kes and vei n s, formed by tran slation Of metalliferous portions, usually upwards or laterally ,

an d

frequen tly exten din g beyo n d the boundaries of the basin ; the “clearest examples o f this typ e are afforded by the tin and tun gstendeposits, while a similar o rigin may be postulated for a great n umbero f o thermetallic o res , in cludin g copper, lead, zin c, arsen ic, an timo n y ,

bismuth, mercury ,silver, and go ld . It appears probable that, as

a result of extended study it will become possible to draw upfurther gen eralization s, by assign in g each metal or group of

metals to its own p etrographic ro ck - type . Thus it appears thatgo ld is specially characteristic of . the mon zon ite group , while the rareearths are con cen trated i n to highly alkalin e partial magmas .

With regard to the actual mechan ism o f differen tiation,the subj ect

o f so much discussion of late y ears amon g p etro logists,the matteris o f min or imp ortan ce ;‘ it is the effects with which we are really'

con cern ed . All the facts go to show that some sort of sp littin g of

magmas must have o ccurred the question of how or'why is main ly

o f academic in terest . The chief b attle at presen t is betweeh the

advo cates o f differen tiation - by diffusion before formation o f‘

so lid

crystals, and differen tiatio n by gravity after the crystals are formed,while the

'

immiscible liquid theory comes in a bad third . Now it isobvious that partial magmas which are still liquid after thedifferen tiation can n o t have been formed by sinkin g o f so lid crystals ,o r

,at an y rate, bOth fraction s can n o t . The upper fraction might,

of course,.becoin e impoverished - ia certain constituents by sinking

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F. R. O’. Reed- Fau n a. of L. Devon ian of Torquay . 29 -9

summarize in a graphic form the ideas here put forward and to

con struct a gen ealogical tree o f the ign eous ro cks an d their relatedore - dep osits , tracin g their descen t by successive step s from a

hyp othetical primi tive magma ,through various stages o f

differen tiation to the in numerable an d varied typ es that we seeto - day . This must be regarded,

however, as merely an attemp t ,and must n ot be taken to o literally ,

sin ce the data available are as

y et in sufficien t for dogmatism on man y po in ts . As already statedthe who le question o f the actual physicalmechan ism o f differen tiationis still subjudice between the diverse opin io n s expressed by emin en tauthorities it is as y et to o early to decide . The fact remain s thatsome s ort of splittin g of ro ckf so lution s must have occurred ; thatis n ot disputed by an y o n e

, but it is improbable that we shall everbe in a position to state exactly what has happ en ed in every case .Nevertheless, it is clear that these pro cesses, whatever they were ,have been the domin an t factor in the origin and primary distributionof the depo sits of the useful metals on which so much o f the - world’

s

industrial developmen t depen ds .

No te s On the Faun a o f the Lowe r Devo n ian Beds o f

To rquay .

By F . R. .COWPER REED , Sc.D. , F . .G S

PART I .(PLATE IV. )

In troductory Remarks .

OUR kn owledge of the faun a con tain ed in theLowerDevon ian bedso f En glan d is extremely imperfect an d un satisfactory , partly

owin g to the scan tin ess of the material which has been co llected,

and partly to the po or preservation o fmost of the fo ssils themselves .

The lists o f gen era an d species given in the Survey memo ir (Ex plan .

Sheet 350) dealin g with the Torquay district are n ot exten sive,and in man y cases the determin ation o f the species or even the gen erais op en to doubt . Correlation in detail with the well - established an d

richly fossiliferous Lower Devon ian o f the Con tin en t is almostimp o ssible in such circumstan ces, but Kayser in 1889 , on the stren gthof the palaeon to logical eviden ce which he obtain ed on the spo t,correlated the beds at Meadfo ot with the Lower Coblen zian .

1 Thefossils whi ch he co llected and iden tified from this lo cality were thefo llowin g Rhen ish sp ecies : Z aphren tis oo litiea,

Rhyn chon ella

daleiden sis , Ckon etes sarcin ulata, Sp irifera kysterica, Sp . p aradoxa ,

Strophomen a of. Murchison i , Pterin ea costata .

Classification of the Lower Devon ian Beds of Torquay .

The division of the Lower Devon ian o f theTorquay district in toa lower p ortion termed the Meadfo o t Beds an d an upper portion

1 Kayser, Neues Jahrb. f Min . Geol . , 1889 , i , p . 188.

F. R.) Cowp er Reed

termed the Staddon Grits is adop ted“

in the Geo logical Surveymemo ir (Exp lan . Sheet 350, the basal group o f the LowerDevon ian , the Dartmouth Slates bein g con sidered to be

un represen ted there . The boundary between the Meadfoot Bedsan d - Staddon Grits is n ot satisfactorily fixed

,but the two prin cipal

exp osures which have yi elded most o f the fo ssils here describedare resp ectively n ear Kilmorie House

,in Meadfo ot Bay , and in the

New Cut, o n the Lin combe Drive . The litho logical characters o f

the beds at these two lo calities as well as the con tain ed faun as are

sufficien tly distin ct . The red fossiliferous beds at Smugglers’ Covediffer somewhat in litho logical characters from those of the New Cut,and . con tain a differen t assemblage o f fossils, so far as the scan tyfauna 1s kn own, but they are ascribed to the Staddon Grits in theabove men tion ed memo ir o f the Geo logical Survey .

Undoubtedly there Is much scope for further systematic co llectin gof fossils from these beds

,and though the specimen s are as a rule

po orly preserved o r fragmen tary , y et they frequen tly admit o f

sp ecific iden tificatio n when studied alo n gside of better materialfrom the Con tin en t .The co llection s in the Sedgwick Museum, Cambridge , have

supp lied most o f the sp ecimen s o n which the fo llowin g n otes are

based, but the Lower Devon ian fossils in the Torquay Museum ,the

Jermyn Street Museum,an d the British Museum have also been

examin ed, an d my than ks are due to Mr . Harford Lowe , Dr . Kitchin ,

and o thers for much assistan ce In my wo rk .

Previous Literature .

A large number of fo ssils were described or recorded by Phillipsin his Palaeozoic Fossi ls of Cornwa ll and D evon (1841 ) fromMeadsfo ot or Meadsfo ot San ds but on ly in some cases(marked in the fo llowin g list) have the origin al specimen s .beentraced, and with regard to the remainder o f the typ es some doubtexists . The n ames fo llowin g In brackets are tho se used In the presen tarticle .

*Pleurodictyum p roblemaficum Go ldf.*Nucula ovata Sow . Cleidop korus

- subovatus sp .

*Avieu la an isota Phill . Florin ea an iso la) .*Orthis sordida Phil l . Ckon e les p lebeia Schn ur) .0 . p lieata Sow. 1840 (n ot 0 . p licata Sow. , Davidson , Mon . Brit. Foss.

B i ach iii, p . 245 )

0 . granulosa Phil l . (gen us doubtful ) .Sp irifera costata Sow. S . subcusp idatus) .Euomphalus serp en s Phill .

*Bel lerop hon tr ilobatus Sow . Bucan ie lla sp .

Orthoceras ten taculare Phil l .*Homalon otus Sp . H. armatus Burm

‘

.

Etheridge, sen . ,in 1867 1 recorded the fo llowin g Lower Devon ian

sp ecies from South Devo n, but whether all came

,

from the Torquaydistrict is un certain

,as is also the accuracy of the iden tificatl o n s .

1 Etheridge , Quart. Jcum . Geo l . Soc.

,vo l . xxii i

,1867, pp . 5 79, 6 19

- 25,636,

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802 If”. R. Cowp er Reed

Woodward 1at the same time described and figured a n ew species

,

Homalon otus gon iop ygaeus , from Smugglers’ Cove , and a pygidiumwhich he attributed to H. Champ ern own ei .

In 1901 Whidborn e 2 described some supposed Lower Devon ianfo ssils from the site o f the Pen gelly Memorial Hall

,Torquay , but

Messrs . Jukes - Brown e and R . B . Newton 3subsequen tly disputed

the accuracy o f his determin ation s and regarded the faun a as

indicatin g Middle Devon ian beds . With the latter co n clusion thepresen t author is compelled to agree .Note — In the fo llowin g descrip tion s o f the sp ecies the letter S.

den o tes that the sp ecimen is in the Sedgwick Museum,while the

lettersM.P .G. an d T . resp e ctive ly in dicate the Jermyn StreetMuseuman d the Torquay Museum . The in dex n umbers fo llowin g theseletters refer to the in dividual sp ecimen s or tablets in the co llection s .

CRUSTACEA .

Gen us HoMALONOTUS.Homalon otus (Digonus) gon iop ygceusWo odward.

1882 . Hon

B

i

plon otui

gon iop ygceus Woodward, GEOL . MAG . p . 157, PI IV1 w

19 18 . Ho'malin otus (Digonus) gon iop ygceus Re ed, GEOL . MAG . , pp . 317, 324 .

The origin al specimen ,con sistin g o f a pygidium ,

which is in theSedgwick Museum,

was described by Dr. Wo odward as fo llows :The axis is very broad _

l n prop ortion to the lateral p ortion s, an dthe division between them 1s but slight . Breadth o f axi s at proximalborder 6 lin es . It IS comp o sed o f from 12 13 an nuli or coalescedcaudal rin gs, the corrugation s o f which are slightly ben t downwardson each side an d con tin ued to the border of the pygidium as welldevelop ed side—ribs . The co stae dimin ish in size an d stren gth fromthe proximal border, till they disappear n ear the hinder part of theaxis about 4%lin es from the extremity , which is smo o th or n early so .

There are n o sp in es or o ther orn amen tation on the surface of thespecimen .

A few addition al remarks may here be made on this pygidium .

It has an elon gated,triangular shape , but its lateral edges are hidden

by matrix,an d its tip

‘

is slightly broken . The convexity of thegen eral surface is gen tle at the proximal end, but in creases

‘

somewhat

towards the tip . The sides o f the pygidium converge at first at anan gle o f about 45 degrees, but behind the p leurae the rate of taperin go f the pygidium i s rather slower . There are o n ly 11 - 12 distin ctrin gs o n the axis, the p o sterior fifth part o f the axis havin g then arrow rin gs o n ly fain tly marked

,an d fin ally becomin g obso lete .

The axis is very greatly convex in fron t,and tap ers rapidly , but

becomes more con vex an d tapers more slowly towards its indistin cttip ,which forms a blun t p o in t circumscribed by a weak furrow, and

l Woodward,ibid . , 1882, p . 157, P] . IV, Figs . 1 - 3.

2 Whidborn e ,ibid . , 1901 , pp . 533—40, Pl . XVIII .

3 Juke s - Brown e Newton ,ibid. , 19 14 , p p . 31 1 - 18.

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forwards at first with a slight convergen ce, but then rather sudden lybending inwards to traverse the pre g- labelle r region and un i te i n a

short median po in t, thus con j o in tly formin g a distin ct tran sversesuture, which defin es the prora posteriorly . Ep istomal rostral)sutures arisin g from the p o in ts at which the facial sutures .bendinwards

,and formin g a pair o f short subparallel sutures boundin g

the prora laterally , and cuttin g the an terior margin o f the headshield at right an gles . Ep istomal rostral) plate situated o n

lower surface o f head- shield, subtrian gular in shape,bearin g a stout

median ap iculus, an d bounded by the in ferior con tinuation o f theepistomal sutures, which cut it off from the flatten ed .trian gularlateral portio n s o f the doublure . Cheeks with gen eral surfaceco nvex and elevated . Free cheeks

,with in n er portio n swo llen and

risin g to maximum height at ey es, havin g large rounded boss or

tubercle situated towards 'margi n slightly in . fro n t o f eyes ;margin simple, without defin ite border . Ey es small

, situated ratherclo se

‘

to the glabella on elevated portion o f che cks at level o f secondlateral glabellar tubercles . Thorax o f 13segmen ts, stron gly co n vex .

Axis broad, gen tly convex , fain tly marked o ff from p leural p ortion s .

Axial rings bearin g two pairs of tubercles, o f which the outer on esare the larger . Pleurae arched down on each side , gen tly flatten ed

,

particularly towards extremities, which are o btusely rounded an d

slightly curved forwards . Twelfth p leura bearin g large roundedboss at half its len gth, but absen t from eleven th and thirteen thpleuree . [An terio r thoracic segmen ts n ot

“

sufficien tly preservedfor determin ation o f characters ] Pygidium elon gated, semielliptical in shap e , with simple lateral margin s, but furn ishedp o steriorly with a short bifurcated spin ose pro cess .

'

Axis lon g ,con ical, convex

,slowly tap erin g , comp osed o f eleven complete

rin gs, with traces o f one or two more very fain tly indicated ringsfo llowed by a short n on - an nulated termin al portion with a blun ttip n early touching base of posterior forked process . Axial rin gswell defin ed

,some bearing tubercles i . e . fourtubercles on the first

rin g like those on the last axial rin g of the thorax , two fain t on es onthe secon d rin g , and two distin ct on es on the third and fourth rin gs,apparen tly co rresp onding with the outer on es o f the first rin g ;the fifth ri n g has two smaller on es

,apparen tly correspon din g with

the in n er pair the sixth rin g has n on e the seven th,rin g has the

two outer o n es ; the eighth to ten th rin gs have on ly fain t traceso f on e cuter pair; the eleven th has on e more distin ct pair . Axialfurrows stron g , distin ct . Lateral lobes arched g

'

en tly d own on eachside

,with smo o th undefin ed n arrow border . Seven o r eight distin ct

flatten ed pleurae on each side , n early straight, but with the endsslightly curved,

n ot reachin g margin , and with traces o f a large lowboss or tubercle o n first p leurae -

at about two thirds its lengthand of .a more distin ct on e o n the fourth p leura at about half itsl en gth . Po sterior en d of pygidium furn ished with apair of closelyplaced

,slightly divergin g curved sp in es

(

arisin g from a common

Faun a of the Lower Devon ian Beds of Torquay . 305

base, horizon tally extended,an d about o n e - sixth the len gth of the

ygidium . Surface o f shell o rn amen ted with small distan t gran ulDimen sion s —{The sp ec1men 1s laterally compressed an d disto rted . )

mm .

Le n gth of head - shie ld (actual ) about

Width o f he ad - shie ld (actua l )Len gth o f glabe l laWi dth o f g labe l la at base

Le n gth o f p ygidium (actual ) to base of Sp in e s

Width of py gidium (actualWidth o f axis o f p ygidium (actual ) at fron t e n d

Len gth o f termin a l Sp in e sHordizon r

—Red Beds (Staddon Grits) .Locality .

—NewCut,above Meadfo ot Bay , To rquay . Sedgwick

(S 88)

Remarks — T he material on which this n ew sp eciesi s founded con sists o f the laterally compress ed an d somewhatobliquely distorted cast an d in tern al impression o f a n early completeindividual (S. All the p arts o f the body are in their n aturalp o sitio n ,

excep t the head- shield, which has been ben t back un derthe body an d thus broken o ff from

' the thorax, but it is on ly slightly

disp laced from its prop er position o f attachmen t . The in tern al casto f the h ead—shield therefore p o in ts backwards in the sp ecimen ,

d is attached to the impressio n o f the thorax an d pygidium . Therealso the impress-ion o f part o f the doublure an d ep istomal p late

o f the same head—shield,but the cast o f these parts is n ot preserved .

VOL . LVII .

— NO . VII . 20

306 Faun a of the Lower Devon ian Beds of Torquay .

The thorax 1s n ot Well exhibited,bein g crushed an d hidden by

matrix,but the last three or four segmen ts are sufficien tly p erfect

to show the tubercles o n the axis an d the n odes on the p leurae . Thepygidium is n early comp lete, though distorted ; the right laterallobe is almo st un in jured ; the axis exhibits its characters

_well inthe cast and imp ression , and the bifurcated termin al sp in e showsdistin ctly o n the left side o f the impression ,

but the cast has thep o sterior en d o f the pygidium broken o ff .

There 1s also a p ortio n o f a large pygidium from the same localityin the Sedgwick Museum (S. which i s represen ted by the in tern alcast and the extern al impression , an dmay belon g to the same sp ecies .

This sp ecimen has its axis,measurin g over 30 mm . in width

,at its

fron t end, but on ly four rin gs are preserved . Of these the first an dthird rin gs bear two pairs o f tubercles

, of which the outer on es are

the larger ; the seco nd rin g o n ly p o ssesses on e pair co rresp on din gto the outer on es, an d the fourth rin g on ly the in n er pair .

With regard to the relatio n s o f this species, we must first n o ticethe close resemblan ce . o f the pygidium to that of H. e longatus,Salter, 1 from the Lower Devo n ian o fMeadfo o t, but the fo rked mucroat its extremity is p eculiar, an d recalls the sp ecies from the Rhin edescribed by Ko ch2 as H. aculeatus

,though in his figure this sp ecial

feature is n ot represen ted . It may be remarked that a similarp eculiar bifurcated termin ation o f the pygidium is presen t in some

American species o f Dalmam'

tes (Odon tocepkalus) from the Devon ian(e .g . D . selenurus Eaton 3

an d D . bt'

fiatus5

Hall The head - shieldan d thorax of H. Ckamp ern own etWo odw .

5app ear to p ossess n early

the same characters as our n ew sp ecies, particularly in thetuberculation o f the head shield, but the an terior margi n , p

‘

rora,

and course o f the tran sverse suture are n o t kn own 1n the imp erfectlypreserved type - specimen which was figured by Wo odward, and thepygidium app ears to be differen t in its axial characters, an d certain lylacks the p o sterior forked termin ation . The axial rin gs o f the thoraxare also stated to bear on ly o n e pair o f tubercles in stead o f two pairs ;The head- shields o f H. armatus Burm .

6an d H. subarmatus Ko ch 7

so far as they are kn own ,seem allied to H. bifurcatus, esp ecially

in their tuberculation,but the pygidia are differen t .

1 Salte r,Mo n . Brit . Trilob . , p . 122

, p l . x, figs . 1—22 Ko ch , op . cit . , p . 93,

t . i , fig . 73 Hal l

,Palaeon t . New York , vo l . vii , 1888 , p . 49 , p l . x iB,

figs . 15—21 .

4 Ibid . , p . 53, p l . XiB ,figs . 22—5 .

5 Wo odward, GEOL . MAGL, 1881 , p . 489 , PI. XIII .

6 Ko ch , op . cit . , p . 84 ,t . i , figs . 1—4 , an d p . 151 .

7 Fre ch , Le th . Palaeo z .,Bd . ii , 1897—1902 , p . 218, text - figure .

(To be con tin ued. )

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308 D. Woo lacott— Exp osure of San ds an d Grave ls

been removed in the course o f quarry in g op eratio n s, an d n o co llec

tio n o f shells has been preserved in an y museum it is therefore o fin terest that a dep o sit has lately been observed which can beexamin ed at an y time by geo lo gists , an d from which specimen s o f

shells can'easily

' be obtain ed . It, is also o f imp ortan ce that theexact mode of origin of these particular dep o sits should bedetermin ed .

The exp osure here n o ticed o ccurs in the cliff o n the south eastflank o f Beacon Hill , about half a mile n orth o f Easin gton statio n ,

which is on the N.E .R . coast lin e midway between Sun derlan dan d Hartlepoo l . It can be examin ed In a steep fo otpath (the topo f which is marked by a stile) leadin g down to the shore at

this p o in t . The dep osit o ccurs at an elevation of about 60 feet ,an d con sists o f ho rizo n tally and regularly bedded san ds an d gravelswhich rest on a level shelf o f Magn esian Limeston e , and which aredistin ctly traceable for a con siderable distan ce to the n orth and

south . The gravels can be seen in the railway cuttin g behin d forat least 30 feet above the level of the shelf. The p ebbles con sistmain ly o f water- worn fragmen ts of Magn esian Limeston e , buto thers of quartz , san dston e, quartzite , rhy o lite (Lake District) , an dChevio t p orphyrite o ccur . It is

,therefore , late Glacial or po st

Glacial in origin .

Man y o f the p ebbles are bored by an n elids (Po lydora ) and o thersby Saxica

'va . In the case of the latter some of the shells are stilli n their ho les . The sands an d gravels are full o f large an d small

,

who le an d broken shells , some o f which are in an excellen t state o fpreservation . The species in clude Littorin a littorea

,L. obtusata

,

Patella vulgaris, Purp ura lap i llus,Myti lus edulis, Cyp rin a islandica ,

Sax icava,Pecten . Several foramin ifera have been proved to o ccur

in the san d . In on e part o f the dep o sit some He lix are cemen ted in ,

and Dr .

'

Trechman n in forms me that in the con glomerate a littlefurther south man y roden ts’ bon es o ccur .

This depo sit 1s o f sp ecial in terest as it is un doubtedly o f the sameo rigin as o ther sands an d gravels which occur 12 miles to the n orthin Durham (their con n exion can

,in deed

,be traced) , and which

can be proved up . to 150 feet above sea - level . "Howse describedsome eaves at Marsden at this height in 1879 , which he said weresea - caves

,an d associated the san ds an d gravels o n these hills with

their formatio n,

1 Kirkby n o ticed sands an d gravels at Fulwell restin gat 150 fee t. Trechman n has co l le cted broken fragmen ts o f Mactra , Turri te l la ,

an d Cyp rin a i slan dica from the Sheraton Kaims , wh ich are about 4 mi le s

in lan d at an e levation o f 400 feet, an d I have co l lected she l l - fragmen ts from

the spre ads o f san d an d grave l at Sal ton Piercy , n ear Hartlep oo l . It is,however , imp ortan t to disco n n ect clearly the she l l - be arin g dep o sits wh ichare foun d ly in g alon g the Durham coast up to 150 fe et from the she l l - bearin g

grave ls an d san ds o f the Kaims , an d the spreads o f san d an d grave l which areassociated with them .

1 Old Sea - cave s an d Sea - beach at Wh itburn Nat. Hist. Tran s .

Northumberlan d ,Durham , an d Newcastle , vo l . vi i , 1 880 , p . 361 .

con ta in i n g Mar in e Shel ls at Easi n g ton . 309

on rock again st a terrace , which he describes as water- worn ,

1an d

Lebour states that the dep osits on Cleado n Hills is a typ ical examp leo f a

_raised beach .

2 I have described both the dep o sits at Cleadon

and Fulwell , an d from the eviden ce obtain ed regarded them as

raised beaches .

3 At the latter p lace the san ds an d gravels were"ban ked up again st a buried terrace an d con tain ed at on e p o in ta large n umber o f who le sp ecimen s o f Littorin a litto'rea . (The buriedrock - terrace app eared to be water - worn an d to have been cut bythe agen t that dep o sited the gravels . ) The sands an d gravels at

Marsden are mapp ed as raised beaches on the Geo logical Surveymap s o f the district . 4 Lamp lugh , Wright , an d some Yorkshiregeo logists have doubted that these dep o sits are o f direct marin eo rigin ,

chiefly because n o raised beaches o ccur in Yorkshire , and

Dr . Trechman n states he is un able to se e the n ecessity of

assumin g these gravel - dep osits to be of marin e origin .

5 Theshells co llected from these deposits have been referred to as havin gbeen obtain ed from kitchen midden s .

6 ' At Ke lsea Hill , n ear Hull ,gravels and sands co n tain in g n umerous marin e shells (some o f whichare similar to tho se o ccurrin g on the Durham coast) can be provedto have been tran sp orted in land fo r some miles by ice from the bedo f the North Sea . Sin ce co llectin g _

in the Easin gton dep o sit I havere - examin ed the Ke lsea Hill dep o sit, an d have been struck by thesimilarity of the faun a an d the mode o f preservatio n of the shellsand by the o ccurren ce in bo th dep osits o f bo red ro cks with Saxicanain p lace , etc . ) but have been impressed by the dissimilarity in theirmode of o ccurren ce .The ho rizon tally an d regularly bedded gravels at Easin gton

seem to have been deposited o n the p latform on which .they lie ,and this level shelf would app ear to have been cut by wave actio nwhen the dep o sit was fo rmed . This formatio n has , in deed,

all thecharacters of a true raised beach , but it is p o ssible that thesemay bedeceptive . After my re - examin atio n o f the Kelsea Hill dep o sitI admit this p o ssibility . I am,

however,n ot con vin ced that the

eviden ce obtain ed from an examin ation o f the depo sit is sufficien tto prove that it is n ot an uplifted sea - beach .

If it is n ot o f direct marin e origin two o ther methods o f formationare p o ssible . It may be material carried by ice from the bed o f

the North Sea an d dep osited above sea - level . (There would appear1 Geo logist, 1 860 , p . 294 .

2 Geo logy of Northumber lan d an d Durham , p . 1 9 .

3 Nat. Hist. Tran s . Northumberlan d , e tc . , 1900 , an d I‘

In iv . DurhamPhil . Soc . Tran s , 1907 ; Quart. Journ . Geo l .

. Soc . , vo l . lx i , 1905 , an d Geog .

Journ .,July , 1 907.

4 Geog . Journ .,July , 1 907, p . 56 .

.

5Quart. Journ . Ge o l . Soc .

, vo l . lxxi , p t. i , 1915 , p . 75 .

6 It is p ecul iar that a kitchen m idden occurs on,

Fulwe l l Hil l s about 20 fe etabove the highest po in t at which the se grave l s occur . The sugge stion that theshe l l s in the se dep o sitswe re from a kitchen midden is shown , by the n ature o f

the deposit at Easin gto n an d al so by the fragmen ts that can be got fromalmost an y exp o sure , to have been n on sen se .

310 D. Woo lacott— Sa'

n ds an d Grave ls wi th Mar i n e She l ls .

to be two ways in which this could have been don e . It could eitherhave been pushed in lan d by

'

the ice an d dep o sited at a higher level ,1o r there is the p ossibility o f it bein g lifted up from the bed o f these a an d carried fo rward as suggested by Deben ham .

2) Its

regularly bedded an d undisturbed n ature an d its exten t are en tirelyagain st the idea that it has been carried by Ice and dumped downin the p lace, in which it o ccurs . On the o ther hand

,the eviden ce is

certain ly in favour o f it havin g been dep o sited in p lace by water ;in deed

,it would app ear to have been fo rmed as a margin al depo sit .

The o ther p ossible mode o f formation is,therefore

,that - it was

formed o n the edge o f a glacier- lake held up by ice ly in g o ff the

Durham coast n ear the end o f the Glacial Period,and that it thus

con sists o f glacial material carried in lan d an d afterwards re - assortedby water on the margin o f an ice - dammed lake . The un brokenn atur

s

e o f the shells and their variety are stro n gly again st thisview . No

]tran sp o rted glacial material from the bed o f the

No rth Sea with such a varied faun a is kn own to exist in Durham .

4

From the Sheraton Kaims,which occur a few miles

_

to thesouth an d are about 4 miles in l an d at an elevation o f 400 feet,Dr . Trechman n

,after careful searchin g , has o n ly been able to

co llect some very broken fragmen ts of Cyp rin a islandica ,Mactra

,

and Turrite lla5

; y et in this dep osit‘who le well - p reserved shells o f

Littorin a,Pate lla

, Saccicava,an d Purp ura o ccur .

_

This dep o sit an d the asso ciated san ds and gravels on the Durhamcoast are therefore o f special in terest . If they are raised beachesthey o bviously raise a peculiar questio n regardin g the n ature o fthe up lift that produced them,

an d if they are n ot they show howdecep tive the eviden ce obtain ed from the mode .of o ccurren ce ofdep ositsmay o ften be , an d they suggest a query regardin g the exten to f the glacier lake o f which they are the margin al dep o sits . All

geo logists to whom I have shown the sands an d gravels at Easin gto n ,

in cludin g some who doubted the existen ce o f raised beaches o n theDurham

b

coast,regard them as bein g o f direct margin origIn , or

admit that the dep o sit is masqueradin g as an up lifted margin almarin e fo rmation . Certain ly geo l ogists who described thesesup erficial dep o sits o n the Durham coast as raised beaches wouldapp ear to have been justified . Now that a fairly comp lete recordo f the glacial dep o sits o f this coast has been wo rked out it app ears o f

impo rtan ce that the mode o f origin o f these particular formation sshould be determin ed . They can be muchmore clearly examin ed at

1 Depo sits have be en observed raised from the sea bed in Sp itsbe rgen byGarwood , Grego ry , an d Lamp lugh .

2Quart. Journ . Geo l . So c - vo l . lxxv,

1 920 .

3 It i s admitted that she l l be arin g grave ls have be en tran sp o rted in lan d 1n

Coun ty Durham . The que stion at i ssue is whe ther there has be en an up l ift o f

the coastal area o f Durham sin ce Glacia l time s .

4 I have n ot se e n an y P ate l la in p lace o n the rock she l f, although some

app eared to have be e n attached to the large p ebble s in th e grave l .

5Quart. Journ . Ge o l . Soc . , vo l . lxxi , 1 91 5 , p . 74 .

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L . F. Sp al

tli fi Ju rassi c Ammo n i tes fr om East Afri ca . 31 1

Easin gton than at an y o ther p o in t , and a thorough examin atio n o f

this dep o sit should fin ally settle the question as to whether raisedbeaches do o ccur o n the coast of n orth east En gland . I should beglad to give an y further particulars to an y geo logistswho may desireto examin e this dep osit, an d if it can be arranged should be p leasedto accompan y them to the exp osure . An y expressio n o f op in io nregardin g the mode o f o rigin o f this dep o sit after it has beenexamin ed would be welcomed . I have p laced a co llection o f shellsfrom it in the Sunderland Museum , and have also given somesp ecimen s to the Curato r o f the Han cock Museum , Newcastle .

On Jurassic Ammo n ite s from East A frica, c o lle cte d by

Pro f.'

J. W. Gre go ry

By L. F . SPATH,B .Sc .

,F.G.S.

(PLATE v. )

THE small but very in terestin g co llection of Ammon ites describedIn the fo llowin g pages was obtain ed durin g the summer o f

1919 by Professo r J . W. Gregory ,to whom the writer is indebted for

p ermission to study them . There are seven sp ecimen s altogether,three of them fragmen tary , and all probably origin ally pyritized,

but n ow con verted in to limon ite . Though immature or fragmen tary ,

al l the sp ecimen s were seen to have indication s o f suture—lin es , sothat their study promised defin ite results even if, at first sight, itwas diffi cult to place the fauna in the geo lo gical sequen ce . Sup erficially , there was greater resemblan ce to the Lower Cretaceousfaun a (With Phylloceras o f the ketcrop hyllum group an d Lytoceras

guadrisulcaturn ) described from East Africa by Krenke l 1 than ,to

the Sequan ian faun a o f Mombasa,recorded by Dacqué ,2 an d a large

series o f which is preserved in the British Museum (Nat . Hist ) .On closer investigation ,

however,an d after preparation o f the

suture - lin es, it became eviden t that the age o f the Ammon itescorresp on ded with the presumed stratigraphical p o sition o f the bedswhich y ielded them, n amely “ Bathon ian , o r p ost - Bathon ian , but

pre Sequanian . ProfessorGregory adds (in litt . ) that theAmmon itebeds [limesto n es an d shales] are separated from the fo ssiliferousSequan ian by a co n siderable thickn ess o f strata . The corals o f thelimeston e immediately un derly in g the Ammon ite bearin g beds,accordin g to Professo r Gregory ,

are n o t o f the same gen era as thekn own Batho n ian corals of East Africa . Also they are n o t the samespecies as those o f the Batho n ian o f Kutch

,an d Professo r Gregory

was at first disp osed to put them as post - Bathon ian . On the o ther1 Die Un tere Kre ide von Deutsch Ostafrika : Be itr. Pal . Ge o l . Ost - Un g

vo l . xxiii , p t . iv, 19 10 , p p . 20 1—50,4 p late s .

2 “Dogger un d Malm aus Ostafrika 1b .

, vo l . xxiii , p t. i , 19 10, pp . 1 63,6 p late s .

31 2 L . F. Sp ath— Jurassi c Ammon i tes fr om East Afri ca .

han d, Mr. R . B . Newton compared on e o f the mo lluscs to a sp eciesfrom the Bathon ian o f Abyssin ia .

It was, therefore , Of in terest to obtain,if p ossible , more exact

in formation from a study o f the Ammo n ites,however few an d

fragmen tary these were , an d the writer is o f op in ion that the eviden cep o in ts to a probable Bathon ian 1

age of the Ammon ite faun a .

DESCRIPTION OF AMMONITES

Genus PHYLLOCERAS, Suess .

Phylloceras afi . Kudern atschi Hauer,sp . (Pl . V,

Figs . 1a—c . )1852 . A . hetero -

phy l lus (Sowerby ) , var Kude rn atsch, Amm . Swin itza

Ahh . k .k . R . A . Vienn a , vo l . i , p t. ii , p . 6 , p l . i , figs . 5—9 .

1854 . A . Kudern atschi Hauer, Be itr . K en n tn . He terp

ophy l l . Ost. Mon .

Sitz . - Ber. Akad . VViss , vo l . x ii, p t . iv , p . 902 .

1860 . A . Kudern atschi (Hauer) , Oo ster, Cat. Ceph . . Fo ss , p t. iv, p .

p l . xvii , figs . 9 - 1 1 .

1871 . Phy lloceras Kude Neumayr,Jurastud . (3) Phy llo ce r.

Dogge r Malm Jb. k .k . R .A vo l . x x i,

Hft . iii , p . 310, p l . x ii , figs . 4—5 .

1877 . (Hauer) , Gemme l laro ,

“Sop ra alcun i Fo ssil i

de l la zon a co n Pos idon o znya a lp in a , Gras . di

Sicilia”

Faun e Giur . Lias, p . 128,

p l . xviii , figs. 3 4

1890 . (Hauer) , Jussen Be itr. Ke n tn . K laus

Schicht. N . Alp Jb . k .k . B .A .,vo l . x 1

,

p . 387, p l . i i , fig . 1 .

(Hauer) , Neumayr Uhlig , Ub . v . Abich i .Kaukasus g e samm . Jura - Fo ssil .

”

Den kschr.

.Akad. Wiss . M. Naturw . CL, vo l . lix , p . 33.

(Hauer) , Ho chste tter, Die Kl ipp e v . St. Ve it

b . VVie n Jb. k . k . R .A vo l . xlvii , p t . i ,

p . 14 1 .

1905 . Pop ovici- Hatzeg , Le s Ceph . Jurass .

Mt . Strun ga” Mem . So c . Geo l . Fran ce ,

vo l . xiii,fasc. 3, p . 10 , p l . i , figs . 1—4 .

Dimen sions — Diameter 39 mm .

Height o f the lastwho rl 60 p er cen t Of the diameter .

Thickn ess 38

Umbilicus 5

Descrip tion— This ammo n ite is a typ ical Phylloceras,with almost

clo sed "

umbilicus an d an ellip tical sectio n with even ly roun ded sides .

The sp ecimen is no t p erfect, however, the shell n ot bein g con tin uedin to the mass Of limon ite shown in Fig . l a . Also sin ce the sp ecimenis sep tate throughout , it on ly represen ts the 1n n er who rls of a largerammon ite . The test 1s somewhat imp erfectly preserved,

an d showsfin e , radial striation at the an terior p ortion ,

but n ear the en d Of theshell the orn amen t is greatly worn . Even here

,however, the fin e

1 The zon e Of JlIacrocep hal ites macrocep ka lus (Corn brash ) should be in cludedin 0the Bathon ian , an d the Cal lovian con sidered to beg in with the zo n e of

Prop lan ulites Koen ig i . This is con trary to Con tinen tal usage : but the

(En g lish ) typ e succe ssion s should be adhered to .

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314 L. F. Sp ath— Jurassi c Ammon i tes fr om East Afr ica .

agrees with t he whorl - outlin e .o f' the sp ecimen here described . In

Neumayr’

s

'

figure o f Phyllocer'

as Kudern atscki the ven tral area istrun cated but this flatten in g is shown n either in the typ e n or in theo ther illustration s cited, though Dr . Till 1 app aren tly lays stress o n it .The suture lin e Of the typ e i s slightly more comp licated than the

o n e here reproduced (Fig . as i s also that g iven by Neumayr,an d esp ecially the saddles are slen derer . This differen ce

,however,

is accoun ted for by the differen t size Of the sp ecimen s . Neumayr’

s

figure , o n the o ther han d, shows exactly the same en din gs Of thesaddles as far as the third auxiliary .

The bun dlin g o f the striae seems to become mo re pron oun ced in thelarger specimen s o n ly , but the fact that the o rn amen t is wo rn inthe sp ecimen under con sideratio n gives it a certain resemblan ce toPhylloceras modestum Torn quist 2 from the Son n in ia beds Of theEspin azito Pass . This form

,however

,is thin n er, ,

an d has a largerumbilicus (9 p er cen t) .Horizon and Distribution .

— Neumayr an d Uhlig 3stated . that

(dov‘

vn till 1892) Phy lloceras Kudern atscki was kn own on ly fromthe Mediterran ean Klaus beds _ Lower Batho n ian fi zo n e Of

Parkin son ia ferrugin ea . But In some Of the beds referred to thisho rizo n

,e . g . the haematite beds Of Swin itza o r the Posidon omya

a lp in a beds of the Italian Alp s, the fusca an d even the asp ido ideszon es Of the Bathon ian seem to be represen ted in addition to the

lower zon e . Haug4records Pk. Kudern atscki from the Bajocian

(zon e Of Cosmoceras subfurcatum n iorten sis up to zigzag hemerasp robably ) :o i the Basses - Alp es . The sp ecies has also been foun d inthe Glarn er Alp s Of Switzerlan d,

n ear Hallstatt,Go sau ,

Vien n a,etc .

,

in Austria,in the Carpathian s, in Sicily ,

an d in the Caucasus .

Locality—No . 19 . Frombeside the co ral limeston e on theMombasa

p ipe - lin e at mile 1 53 . (Sin g le sp ecimen . )

Phylloceras sp . in det . (Pl . V,Figs . 2a—c. )

Dimen sion s — Diameter 25 mm .

Height of the lastwhorl 58 p er cen t o f the diameter .

Thickn ess 42

Umbilicus 4

Descrip tion— This specimen con sists Of a little over half a who rl

(who lly septate) an d it has been ro lled,so that though fragmen ts

Of the test remain there is n o trace Of the o rn amen t . The ammo n iteis very similar in shap e to the sp ecimen above referred to PkyllocerasKudern atscki , but a little thicker (42 p er cen t in stead of 38 p er cen t) ,

1 “Amm . Faun a d . K e l loway v Vil lany Be itr. Pal . Geo l . 0 st .

- Un g .,

vo l . xx iv, p t. i i

,19 1 1 , p . 255 .

2 D . Dogg er a . Esp in azito Pass Pal . Ahh . Dame s, N .F. , vo l . iv, p t. ii ,

1898, p . 29 , p l . v (xviii ) , fig . 2 .

3 Op . cit. , p . 33.

4 “Les Chain e s Subalp in e s, etc . Bul l . Service Carte Geo l Fran ce , i ii ,

NO . 21 , 189 1,p . 74 .

L. F. Sp ath— Jurassic Ammon i tes fr ont East Afr i ca . 31 5

an d the p eriphery thus appears more roun ded . The umbilicus isvery small an d deep ,

and the sides are regularly roun ded in to it .The suture - lin e could ‘

o n ly partly be drawn ,an d this p ortion is

comp osite, taken from bo th the an terior an d p o sterior en ds o f thesp ecimen . Apart from the diphy l lic extern al an d two lateral saddlesshown in Fig . 20 , there are three more diphy llic saddles but theremainder Of the suture—lin e, app aren tly co n sistin g Of three moresaddles

,can n o t be clearly made out . The suture - lin e

,then

,differs

from that of the above sp ecimen chiefly in havin g a more complexan d deep er extern al lobe an d a mo re diphy llic first lateral saddle .Observations — There is great resemblan ce in the suture - lin e an d

app earan ce (Of the smo o th in n er who rls) to the Callovian Phyllocerassubobtum

’

forme Pomp eckj1 from Alaska . But this form is a l ittle

thicker,and apparen tly has an umbilical edge, sin ce it is compared

with Pkyllbceras subobtusum Kudern atsch an d Phylloceras Abicki

Uhlig . The fact that the orn amen t is n ot preserved preven ts closercomparison with Pk. isomorphu

-m Gemme llaro ,

2 which has similar ‘

(but variable ) dImen SIOn s . Also the suture - lin e o f this form has

slenderer saddles and fo lio les . Sin ce,however

,the suture - l in e Of

the earlier p ortion o f the Eas t African sp ecimen shows , in this respect,greater resemblan ce to Gemme llaro

’

s figure than the last suture - lin es(a matter Of preservation ) , this po in t is less sign ifican t than thelarger umbilicus 1n the Sicilian sp ecies .

Phylloce'

ras trifo liatum Neumayr3 from the Baj o cian Of the

Carpathian s, also comes close to the presen t form, but its suture lin eis characterized by a triphy llic first lateral saddle . Vacek ‘1

statedthat the specimen from San Vigilio (from which the suture lin egiven by Neumayr in Fig . 2 was taken ) was n o t iden tical with theHun garian Pk. trifo liatum an d belo n ged to Pk. chon omphalurn

Vacek o f a differen t group . This po in t seems to have escap edPrin z

,

5 who se o therwise un con vin cin g division s within the gen usPhylloceras have n ot been adop ted by the writer .

6 Of the Baj ocianfo rms o f Phylloceras described by Prin z , Pb. bacon icum 7 is very n earthe presen t sp ecimen ,

but its suture - lin e is m o re comp lex than theon e here figured (though taken from a larger sp ecimen ) .The absen ce o f co n strictio n s an d its gen eral appearan ce

1 Jurafo ssil .‘

aus Alaska Verb . Russ . Kais . Min eral . Ge s. St . Pe tee

s er . II , vo l . xxxvii i 1900 , p . 247, p l . vii , fig . 1 .

- Faun e Giur . dz Lia -S. , p t . i , 1872 , p . 6, p l . i , fig . 1 ; p t. v,1877, p . 130 ,

p l . x ix . fig . 16 .

3 Jurastudien ,ii lo c . cit. , p . 309

, p l . x ii , figs . 2, 3.

4 Uh. Faun a OOl . Cap San Vig ilio Abb . k . k . R .A Vie n n a ,vo l . x ii ,

1886, p . 69 .

5 Die Faun a alt. Jurabild . NzO . Bako n y Mitt. Jahrb . Un gar . Ge o l .

An st .,vo l . xv, 1904 , p . 40 .

6 Jullien’

s (C. R . somm . Soc. Geo l . Fran ce , Jun e 19 , 19 1 1 ) division s an d

sp eculation s o n sexual dimo rphism amon g Phy lloceras also seem un foun ded .

7 Ib . , .p 38, p l . xxvii, fig . 2 .

31 6 L'

. F. Sp ath— Jurassi c Ammon i tes from East Africa .

characterize the sp ecimen as a member Of the group o f Ph. hetero

p kyllum,an d it is probable that it belon gs to the same lin eage as,

and is a n ear relative o f, PliyllocerasKurl ern atscki Hauer .

Locality— This sp ecimen (NO . 551 ) was foun d (iso lated) to the west

Of the Mwachi River,abou 1

01

.

Phylloceras- cf . Kun tki Neumayr . (Pl . V,

Fig . 3a—c. )1871 . Phy l loceras Kun iki Neumay r, Jurastudien ,

ii : l o c . cit ., p . 312

p l . x i i, fig . 6 ; p l . xiii , fig . 1 .

1905 . Ph. n . sp . i n d . , Pop ovici- Hatzeg ,

Le s Ceph . Jurass . Moy . Mt .

Strun ga lo c . cit . , p . 1 1, p l . iv , fig . 8 .

19 10 . Pk. of . K un tli i (Neumay r) , Till ,“Amm. Faun a d . Ke l loway v .Vil lan y

lo c. cit., p . 253.

Dimen si on s — Diameter 19 mm .

Height o f the lastwho rl 59 p er cen t of the diameter .

Thickn ess 36

Umbilicus 5

Descrip tion— This sp ecimen is a who lly sep tate cast an d has on ly

a small p ortion o f the test preserved, n amely , on the p eriphery ,

n ear the begin n in g o f the outer who rl . Here the orn am en t con sistso f distin ct radial striae (about eleven to the 2 mm . o f test shown )after the man n er o f Pliylloceras Ve lledce Michelin sp . It is a littlethin n er than the two forms previously described ; in its elon gateellip tical section it mo re resembles that referred to Pb. Kudern atschi .

The whorls show their greatest thickn ess about midway betweenthe p eriphery an d the umbilicus the latter is n arrow an d deep .

The suture - lin es are well exp o sed throughout the last whorl .Apart from the eight saddles shown in Fig . there are three more

saddles extern ally ,and about seven saddles in tern ally ,

makin galtogether about seven ty elemen ts . The extern al saddle showsbran chin g Of its termin al leaflets (after the man n er o f Ph. serum

Opp el sp . an d Pb . .semisulcatum d’

Orbign y an d the first lateralsaddle becomes triphyllic owin g to the lean in g over of its origin allytetraphyllic summit to the ven tral side . The three saddles fo llowin gthis are diphy llic, the n ext six mon ophy llic .

0bservation s .

—The absen ce o f co n strictio n s an d o ther po in tscharacterize this sp ecimen as a form o f the group of Pb . hetero

p li ylluin . Though in dimen sion s ,and whorl - shap e it - resembles the

ammo n ite above referred to Pk. Kudern atschi , its comp lex suturelin e distin guishes it at o n ce from that sp ecies . The subdivisio nof the termin al leaflets o f the extern al saddle , however, is in dicatedin Neumayr

’

s figure o f the suture - lin e o f Pb.Kudern atscki ,

1 thoughthis subdivision ismore remin iscen t of Ph. subobtusum Kudern atsch

and man y forms o f the group o f Pb. tatricu 'm Pusch .

The slender whorl - section o f this specimen is n o t un like that o f1 Loc. cit . , p l . x i i , fig . 40 .

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31 8 L . F. Sp a th— Ju rassic A n imo n i tes from East Afr i ca .

is very n ear to the presen t sp ecimen bo th in whorl - shap e an d suturelin e . The latter also greatly resembles Pb . Riazi de Lorio l 1 from theRenggeri marls . The very comp licated suture lin e o f the latter

,

however (at equally small dimen sions) , is distin guished by a lessern umber o f elemen ts .

Horizon an d Distribution .

'

— Pk-

ylloceras Kun tki is widely dis

tributed in_the Callovian Of the Mediterran ean region (Austrian Al p s,

Hun gary , Sicily ,Daghestan ,

an d In dia) . The typ e comes from thezo n e Of Macrocep kalites macrocep lzalus . Haug

2records this sp ecies

with P72 . disp utabi le , Protetragon ites'

trip artitum,an d o ther Batho n ian

fo ssils from Chaudon ,Basses - A

g

lp es, whereas the ammon ites doubtfully referred to it by Waagen 3

an d Neumay r et Uhlig .

4came from

the athleta beds .

Locality .

— NO . 55O/I, Mwachi River, Pip e lin e Cro ssin g . Foun dtogether with Protetragon ites cf . trip artitum Raspail sp . an d

Hecticoceras sp . juv .

P liylloceras cf. disp utabi le Zittel . (Pl . V,Figs . 4a—d. )

1893. Phy lloceras disputabi le (Z itte l ) Pomp e ckj, l o c . cit . Revision , p . 32 .

Se e the re for sy n on ymy .

Hatzeg , l o c . cit ., p . 13, p l . 11

,

figs . 1 te xt fig . 3 ou p . 13,figs . 4 a1id 5 on

p . 14 .

Dimen si on s .

— Diameter 2 28 mm .

Height of the lastwhorl 55 p er cen t of the diameter .

Thickn ess 30

Umbilicus 7 14

Descrip tion— This sp ecimen con sist s o f a whorl - fragmen t, about

27 mm . lo n g, and the above measuremen ts are based o n the '

restoration o f the comp lete shell given in Fig . 4b. The fragmen t isworn ,

an d there is n o trace o f the shell - orn amen t left . The roundedumbilical edge is apparen tly preserved n ear the smaller end,

an d

the section al view, given in Fig . 4c (magn ified two diameters) , is

drawn from this p ortion . Fig . 4a shows the (morpho logically ) leftside o f the sp ecimen ,

which is p o orly preserved,an d do es n ot show the

co n strictio n s . On the Oppo site side , represen ted in Fig . 4b, the twocon striction s are presen t, but they become in distin ct o n the lateralarea . The con striction s pass acro ss the p eriphery with a slightforward ben d, but the forward con vexity at the side an d theumbilical curve , in dicated in the figure , are hardly distin ct en oughto warran t a defin ite descrip tion o f their course . The sides of the

1 Etude sur le s Mo ll e t brach . de l’

Ox f. In f. d . Jura Bern . Mem . So c .

Pal . Suisse ,vo l

‘

. x xv , 1898, p . 1 10 , p l . viii , figs . 8 12 an d te xt - fig. 29, on p . 1 1 1 .

2 Tra ité de Geo logic,vo l . ii . fasc . 2

,1908, p . 1023.

3 “ Jurassic Faun a Of Kutch Pal . In dica ser . ix ,vo l . i 1873, p . 25,

p l . v , fig . 2 .

‘1 LOO. cit ., 1892 , p . 33.

L . F. Sp a th— Jurassic Ammon i tes fr om East Afr i ca . 31 9

fragmen t are fl atten ed,but gradually roun ded Off to the p eriphery ,

an d very abrup tly to the umbilicus ; the greatest thickn ess of the

whorl is at the umbilical edge . The small in clusion shown by theimpression o f the in n er whorl in dicates a fairly large umbilicus .

The suture - lin e is, characterized by the slightly . subdividedtermin al fo lio les o f the extern al saddle

,and by an irregularly trifid

first lateral saddle The lateral elemen ts are highly comp licated,an d bo th the saddles an d their fo lio les are very slen der .

Observation s — The slightly falco id con striction s an d complexsuture - lin e characterize the sp ecimen as belon gin g to the groupo f Phylloceras Cap itan ei (Catullo ) Neumayr . There is greatresemblan ce to the forms figured by Popovici - Hatzeg as ? Pk.

disp utabile Zittel , esp ecially his smaller sp ecimen s ; an d thesection given by that autho r (fig. 3 on p . 13) agrees very well at asimilar diameter . On the o ther han d

,the suture - lin e o f the East

African sp ecimen is more comp lex an d o f the typ e'

Of that Of Ph.

Puscbi Opp el ,1 which accordin g to Till 2 is o ften con fused withPk. disp utabi le . In d

’

Orbign y’

s sp ecimen an d in the examp lesreferred to P71 . Puscbi by Till , however, the umbilicus is o n ly6—7 p er cen t Of the diameter . Petitclerc 3 un ited Pk. Puschi withPk. Lajouxense de Lorio l,4 an d the y oun g o f the latter species wouldagree with the specimen un der co n sideration in the large umbilicusbut the suture - lin e is to o simp le in Pk. Lajouxen se , the whorlsection to o in flated

,an d the con striction s (apparen tly ) too straight .

The sp ecimen o f P11 .,disp utabi le figured by Dacqué 5 from the

Dogger of Pen dambili (railway lin e fromDar- es- Salaam to Morogoro )

differs from the presen t examp le bo th in suture - lin e an d in its deepcon striction s . Acco rdin g to Haug ,6 however, the deep con striction sand promin en t bulges which characterize the typ ical figure Of

Kudern atsch’

s app ear o n ly on the larger;Whorls . The umbilicusalso seems to close with age , fo r in a sp ecimen of 210 mm . diameter,quo ted by Pomp eckj,

7 it amoun ts to o n ly 5 p er cen t of thediameter .

1

There is a resemblan ce to the forms figured .by Vacek 8 as

Pliylloceras ultramon tan um Zittel , but in that group the con striction sare more an gular o n the lateral area

,and the elemen ts o f the

suture - lin e are very simp le an d p lump . This latter characteralso distin guishes the sp ecimen un der con sideration from P77 .

mediterran eum Neumayr, which o ccurs in the macrocepha lus beds of1 Pk. tatricum (Pusch ) in d ’

Orbig’

n y ,Ter. Jurass. , p l . 180 (Opp e l , Pa l . M i tt

1863, p .

2 Lo c . cit. , 19 10 , p . 259 .

3 La,Faun e du Ca l lovien (les Deux - Séures , 19 15 , p . 89 .

4 Etude s sur le s Mo l l .'

e t Brach . de l’

Oxf . In f. d . Jura Lédon ien Mem .

So c . Pal . Suisse ,vo l . xxvii , 1900 , p . 1 1

, p l . 1, figs . 1, p l . i i , fig . 1 .

5 Loc. cit 19 10 , p l . v , figs . 3a 3b.

6 Lo c. cit .,189 1

, pp . 70,73.

7 Lo c. cit . , Revision , 1893, p . 32 .

8 LOO . cit.,1886 , p l . v , figs . 15—20 .

320 L . F. Sp ath— Jura ssi c Ammon i tes fr om East Afr i ca .

In dia an d Madagascar, though the writer found closely comparableammon ites in abun dan ce in the Argovian beds o f Jebel Zaghuan ,

Tun is .

1 The first lateral saddle is trifid in this sp ecies as in the EastAfrican sp ecimen , but the simp le fo lio les o f the saddles represen tedin the figures o f Popovici - Hatzeg 2 an d Prin z 3 are quite differen t .'On the o ther han d,

it ap p ears that, as in the case o f Pb. dis-

p utabi le ,the man y referen ces to Pb . mediterran euon given in palaeon to logicall iterature probably in clude a variety o f evo lute Phylloceras Of theultramon tan um group ,

4an d o f the Cap itan ei group in the case Of

Pb . clisp utabi le . It has already been men tion ed that though thecourse Of con striction s can n o t accurately be determin ed,

the sp ecimenunder con sideration probably belo n gs to this Cap itan ei assemblage .The rectan gular sectio n o f the sp ecimen here described “

mightsuggest con n exion with the gen us Sou ei bJceras The suture lin e,hqv»ever is sufficien tly distin ct from that o f this genus .

Horizon and Distributi on .

— Phylloceras disp utabi le is a Batho n ianform, an d o ccurs (gen erally asso ciated with Pk. Kudern atschi ,Prote

’

tragon ites trip artitum,etc . ) in the South Of Fran ce , the Italian

Alp s, . at Swin itza in Hun gary ,in the Carpathian s, the Caucasus .

It has also been recorded from the Callovian (zon e of M . macre

cephalus) Of East Africa an d In dia,an d Hauer

5has it already in the

Baj o cian (zon es Of Son n in‘

ia”

Rorn an i an d Cosmoceras sub

furcatum) Of'the South o f Fran ce .

Locality— NO . 10

,from the grey , o therwise un fo ssiliferous lime

ston e beside the break -

pressure tan k,mile es o n the Mombasa p ip elin e (together with Sou'

erbyceras sp . aff. tortisulcato d’

Orbign y

1 Jurassic Ammon ite s from Jebe l Z aghuan QJ G S vo l . lxix , 19 13,

p . 561 .

2 Lo c . c1t 1905 , text fig . 6 on p . 15 .

3 Lo c . cit . 1904 , p l . xxxvi , fig . 8 .

4 Hochstette r (lo c. cit ., p . 142 ) state s that P li . mediterran eum begin s In the

Klaus Beds an d ran ge s in to the Titho n ian . This vertical ran ge i s un usual ly

gre at fo r a sp ecie s group ,eve n o f a Phy l locer 13.

5 Lo c. cit. pp . 70, 73.

(To be con tin ued . )

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322 H . A . Baker— Loose Ar en aceou s Sedime n ts .

2 mm d1ameter Grave l grade .

1Very coarse san d

Coarse san d

San d grade

Medium san d

Fin e san d

Coarse silt

Silt grade .

Fin e silt

Clay grade .

Depo'

sits con sistin g who lly Of material Of on e o r o ther o f thegrades sp ecified above do n o t app ear to occur in n ature . Detritalsedimen ts con sist of a mi xture Of certain prop ortion s by weight ofman y Of the above grades, an d it is the purp o se Of a mechan icalan alysis to determin e the prop ortion ate weights Of the gradespresen t in the sedime n t un der examin ation . The allocation of a

descrip tive n ame .to a sedimen t dep en ds, usually ,upon the presen ce

in it of some o n e particular grade which o ccurs in sufficien tly markedp rep onderan ce to in fluen ce the gen eral character o f the who le . But

p rop ortio n ality Of the various grades is o ften o f great imp ortan cein influen cin g t he n ature o f a sedimen t, especially in the case o f thefin er aren aceous dep osits . A san dy sedimen t may con tain a p er

cen tage - weight o f the clay grade, which , though small , is n everthelessen ough

'

to brin g up the capillarity an d water- capacity Of the who leto a value sufficien t to result in con siderable bindin g -

p ower . Sucha sedimen t, when seen wet, in the field

,would be liable to be termed

clay although the same material,seen dry ,

in .the laboratory ,would probably _

be termed san d These poin ts emphasize then eed for a defin ite classification o f sedimen ts, based fun damen tallyup on the grades presen t and the prop o rtion ality by weight o f thesegrades .

Early in 19 19 the opportun ity was afforded the presen t writero f un dertakin g , at the Imp erial Co llege o f Scien ce an d Techn o logy ,a p iece o f work which he had lo n g had in min d,

n amely ,a study of

,

the Lower Lon don Tertiary strata of the southern side of the Lon do nBasin . The sedimen ts to be dealt with bein g in themain aren aceous,it appeared likely that useful results would be afforded by detailedmechan ical an alyses . Pro fessor P . G. H. Bo swell had foun d suchan alytical data o f much service in his study of various dep osits(in cluding the Lower ‘

London Tertiaries) in East An glia ,an d had

further shown the great value of such work up o n sedimen ts frOm theeco n omic p o in t Of View . Acco rdin gly much time was Sp en t incarry in g out a

"

very large number o f careful mechan ical an aly ses,an d the opp ortun ity was taken Of revisin g the methods Of experimen tin this con n exion . From results Obtain ed,

the writer is convin cedo f the usefuln ess an d importan ce o f this lin e of work to g eo logists,

H. A . Baker— Loose A r en aceous Sedimen ts . 323

an d hop es that it will receive the atten tion which it deserves at thehands o f future workers .

It is proposed in the presen t pap er to deal with some po in tsco n n ected with the revised methods of exp erimen t in carry in g out

mechan ical an alyses, an d to give , in outlin e,the main results arisin g

from this side of the writer’s investigatio n s, so far as the Than etBeds alo n e are con cern ed .

All the data were obtain ed by elutriatin g samp les of the varioussedimen ts in glass tubes of a sp ecial shap e , by means of upwardcurren ts of water at kn own speeds . Siftin g , by mean s of meshesan d sieves, was n ot resorted to for the fo llowin g reason s (1 ) . Thedata obtain ed by the use of sieves are n o t trul y comparable withresults given by the employmen t of curren ts o f water

,owin g to the

differen t behaviour o f the in dividual grain s in the two cases . A

grain may be con sidered as p ossessin g three dimen sion s at rightan gles to . each o ther, a maximum

,a min imum

,and an in termediate

dimen sion . When p laced o n a sieve it is the in termediate dimen sionwhich decides whether the grain pass the sieve or n ot

,since ,

if this permit,the grain will turn up o n en d and drop through the

sieve . When buoy ed up by a curren t o f water the grain turn s so

as to expose its greatest cro ss—section al area to the curren t, an dcon sequen tly , l n this case , the maximum dimen sion ,

as well as thein termediate on e , is o f large accoun t in deciding whether the gramshall remain in the tube or be washed off . (2 Meshes and si eves“,esp ecially fin e on es, are liable to be in accurate . It IS n ot easy toobtain a sieve of an y specified gauge , an d the ap ertures in an y sieve ,esp ecially after a little wear an d tear

,show a serious variation

amon g themselves . (3 Sieves are very liable to become cloggedup . This frequen tly o ccurs durin g a siftin g pro cess , so that evenafter pro lon ged agitation of the si eves large amo imts of fin e materialwi ll y et remai n en tan g led within the meshes of even coarse sieves .

ELUTRIA ’

I‘

ION BY WATER CURRENTS : 1 (1 ) PHYSICAL BASIS or THE

METHOD .

When mi n eral grain s are

‘

allowed to settle freely in a liquid theydo

'

so under the in fluen ce o f gravity, but the rate o f subsiden ce1 Gen eral accoun ts o f the method o f con ductin g e lutriation experimen ts have

be e n g iven by Crook an d also by Bo swe l l . Fo r the se an d for o ther in formation

con ce rn ing the pro ce ss , co n sult the fo l lowin g

(1 ) Cro ok , App en dix to Hatch & Bastal l , Sedimen tary Books , Lon don ,1 9 13,

p . 349 .

(2 ) Bo swe l l , Bri tish Resources of San ds an d Books used in Glass - makin g ,2md (comp l ete ) ed . ” Lon do n Lon gman s , Gre e n Co . 1 9 1 8 .

(3) Bo swe l l , Bri tishResources of Refractory San dsfor Fu rnace an dFoun dry .

Purp oses , Lon don , Tay lor Fran cis , 1 91 8 .

(4) Stadl er , Gradin g An alyse s by Elutriatio n Tran s . In st. Min . an d

Metal- l . , x ii , 1 9 12—13, p . 686 .

(5) Ke ilhack , L ehrbuch der p rakti schen Geo logi e , 1 908 ,2n d ed . , Stuttgart .

(6) Rie s , C lays , their Occurren ce , P rop erties , an d Uses , 2n d cd .,New York ,

1908 .

324 H . A . Baker— Loose A ren aceous Sedimen ts .

o f an y specified grain is con tro lled by its size,specific gravity , an d

shap e , as well as by the den sity and visco sity o f the liquidin which it is subsidin g . Exp erimen tal work has shown that thesize or surface - area o f the grain s is the domin an t con tro llin g facto r,an d is of much more accoun t than sp ecific gravity in the case o fsmall particles . Where the aggregation o f grain s con sists largely of

variously sized fragmen ts o f the same min eral,as

,for examp le ,

in a quartz san d the differen ce o f free - settlin g vel'ocity or

hydraulic value of the grain s affords a con ven ien t mean s o f

classify in g them accordin g to size. Although in crease o f temp eraturedimin ishes both the den sity an d the visco sity o f the water which issortin g the grain s it is p o ssible to app ly an appropriate correctionto coun terbalan ce these variatio n s . The p rocess of elutriatin g bymean s of curren ts of water is based upon the fun damen tal assump tio n(which is justified by results) that the fin al velo city o f subsiden ceo f a grain is that o f the upward curren t of water which will justkeep it in susp en sio n . Labo rious exp erimen tal work on the relatio nbetween diameter o f grain s and rate of free settlin g in water hasbeen carried out in the case of the min eral quartz

,and has y ielded

data up on which the elutriation pro cess is based . Lo ose aren aceoussedimen ts

,bein g comp osed very largely o f quartz grain s, can be

c lassified in to grades down to,an d below

,material o f 0 1 mm .

d iameter,an d if n ecessary up to about 12 mm . diameter

,an d in the

s eparation o f an y specified grade the exp erimen ter may make themin imum an d maximum limits o f size as n arrow as he p leases .

From the purely mathematical p o in t o f view the problem of.

thesubsiden ce of a small sphere in a fluid medium was in vestigated bySir G. G. Stokes .

If a small p article , assumed spherical , o f den sity p l a ud radius afall through a fluid o f den sity p an d visco sity ,

u,an d at

“

rest, it willbe accelerated at first : This acceleration is n ot, however, co n stan t,but decreases with in creasin g sp eed,

so that the particle , if aflordedthe opportun ity ,

even tually moves un iformly with velocity2 p l

—p 2

9 Mga .

If the particle is at the bo ttom of an elutriator tube an d ite n coun ters an upward curren t o f water of velocity V,

it will in itiallybegin to move up with the water with the same velocity . But

gravity will retard it , an d' it will suffer a n egative acceleration .

Con sequen tly its speed will be reduced,and it will ultimately , if

afforded the o pp ortun ity , move upward with -

velo cityV— U=V

9 1 i t

If V —2

-

ga2 the particle will cease to rise after the

steady state has been attain ed .

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H. A . Baker— Loose A r en aceou s Sed imen ts .

Hen ce , fo r grain s o f a sp ecifiedmin eral, exceedin g about mm .

diameter,subsidin g in water at con stan t temp erature, we haveV 7a1/ D where k is a co n stan t .

Richards found that this Law o f Eddy in g Resistan ce is moren early true the greater the velo city ; that is, when the true viscousresistan ce plays a con tinuously less imp ortan t p art, an d the eddy in gresistan ce an increasin gly imp ortan t part . If we take the valuefo r the con stan t k as in dicated by Richards ’ work, we find thatthe velo cities calculated from the fo rmul a for grain s between '

2 an d‘

5 mm . diameter are to o great . In the p lo t shown o n the graph(se e Fig . 1 ) o f the Law of Eddy in g Resistan ce the related values

FIG . 1 .

— Pl o t o f Richards ’ data on the fre e - settl in g ve l ocitie s i n water o f

quartz grain s l e ss than ~5 mm . diameter . With p l ots o f the laws o f

viscous an d eddy in g resistan ce in se rted f or comparison .

assumed for the purp ose o f determin in g 10 were '

327 mm . for D

and 361 2 mm . p er second for V,fo r the temp erature of 15

°

C. ,

o ther in dep enden t wo rk havin g indicated the reliability o f thesefigures . Even with the in troductio n of this modification o fRichards ’k it can be seen from Fig . 1 that Richards ’ results, fo r grain s betweenabout '2 mm. and

'

5 mm . diameter, do n o t agree closely with thistheoretical law o f eddy in g resistan ce .

H . A . Baker— Loose A r en aceous Sedimen ts . 327.

In elutriation work on aren aceous sedimen ts it is imp ortan t forthe in vestigator to kn ow accurately the rate o f settlin g of quartzgrain s between the limits o f '

01 mm . an d about '4 mm . diameter .

This matter has recen tly been made the subj ect o f careful investigation by an other worker, who very kin dly p ermitted the presen twriter to make use of his results (which are as y et un published) i nthe carry in g o- ut of mechan ical an alyses . It IS n o t fittin g to discusshere the un published work o f an o ther, but the writer may , p erhap s ,be p ermitted to state that the behaviour o f subsidin g grain s, bet-weenthe limits o f '

2 mm . an d'

5 mm . diameter,shows n o clos er adheren ce

to the law o f eddy in g resistan ce than do es that o f grain s betweenthe limits o f

'

01 mm . an d '

2 mm . diameter to the law o f viscousresistan ce . In fact

,the rates of subsiden ce of grain s between the

limits. of 'Ol mm . an d'

4 mm . diameter vary in a defin ite way ,which is very clearly a compromise between these two laws .

In the absen ce of published in formation con cern in g this laterresearch

,which is o f fun damen tal imp ortan ce to wo rkers in terested

in the mechan ical an alysis o f sedimen ts, it may be remarked thatthe data are o f such a character as to len d themselves to

mathematical expression in the form of formulae . A series of

fo rmulae, by mean s o f which the r ate o f subsiden ce in water of a

quartz grain can be calculated,when the diameter of the grain an d

the temp erature o f the water are kn own ,has been . wo rked out

by the presen t writer, who hop es , at a later stage , to co llaboratewith the author o f the research in discussin g this p omt .

CONDUCT o r ELUTRIATION EXPERIMENTS .

The reason s for rej ectin g the rap idly workin g , two -

'tubed Cro oke lutriator in favour o f the more tedious Schoen e sin g le - tube processmay be stated . The Cro ok elutriato r p ossesses the advan tage ofe ffectin g the separatio n o f a sample in to three grades in o n e operation .

The disadvan tages, however, far outweigh this in itial gain . TheCro ok elutriator con sists o f a pair o f tubes, on e below the o ther,the water passin g from the lower, smaller tube to the upp er, wide.tube

,an d then ce escap in g from the j et - tube carried by the latter .

The diameters of the two tubes are adjusted to each o ther an d to

the water- supp ly in such a way that the total sand -

grade mm . )in the samp le u n der examin ation is retain ed in the lower tube , theto tal silt grade (0 01 to 0 1 mm . ) is retain ed in the upper tube ,an d the clay grade 01 mm . ) is washed away . A practicaldifficulty which meets on e at the outset is the matter o f adjustin gthe diameters o f the two tubes so as to preserve the correct rati obetween them . It is o n ly by chan ce that tubes

,o f precisely the

diameters required can be secured,an d in the Cro ok elutriator,

as set up in labo ratories, the adjustmen t is usually more or lessapproximate .

328 H . A . Baher— Loose Ar en aceou s Sedimen ts .

' The flow o f a liquid through a tube is either o f the steady ,irro tation al typ e , in which the liquid is movin g in cy lin drical layerscoaxial with the axis o f the tube

,an d the lay er o f liquid again st

the ‘ wall o f the tube is at rest, or

l

o f the ro tatio n al , eddy in g typ e ,in

' which the velo city of the curren t is more o r less un iform overa large part of the cro ss sectio n o f the tube . To obtain the firsttyp e o f flow certain prelimin ary p recaution s must be taken ,

but in

the case o f the curren t o f wate r passin g through an elutriato r thesep recaution s are ign ored,

so that we have to deal with the case o ieddy in g flow . The tube wall has an imp ortan t retardin g effectup on the curren t

,an d the ratio o f the circumferen ce o f a tube to its

cro ss sectio n varies in versely as the diameter . Osborn e Reyn o ldshas stated that the critical mean velo city at which the steady typeof flow breaks up an d is rep laced by eddy in g flow varies inverselyas the diameter o f the tub e . Hen ce , with so n arrow a tube as thesmaller tube o f a Cro ok elutriato r there is a much stro n ger ten den cyfo r the flow to approximate to the steady ,

irro tatio n al typ e thanin the case o f a fairly wide tube . Fo r the steady ,

irro tation al typ eo f flow the fo rmula

r’

) app lies

velo city at a p o in t distant r from axis of tube ,vo lume passin g a cro ss sectio n o f the tube in un it time(o r outflowin g from j et in un it time) ,

a radius o f tube .In the cen tre o f the tube r 0

,co n sequen tly

an d sin ce%1s the average velocity of the curren t, as calculatedfromthe outflow from the j et

,it fo llows that , in the cen tre o f the

tube the velo city o f the curren t is tu ice '

as fast as the calculatedaverage . Therefo re, in the smaller tube o f a Cro ok elutriator,although the con dition s requisite for steady ,

irro tation al flow are

n ot comp letely realized,the velo city of the curren t in the cen tre

of the tube is appro achin g double the value o f the mean sp eed forwhich the app aratus has been adjusted . Hen ce much materialwill be washed o ff which should be retain ed within the tube , an da mechan ical an alysis, effected by mean s o f a Cro ok elutriator, willalways give to o low a p ercen tage weight fo r the san d grade , an d to ohigh a p ercen tage weight for the silt grade . The seriousn ess of theerror invo lved is Seen at o n ce from the fo llowin g comparativeresults

,which are selected from a n umber o f tests made by the

writer

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330 H . A . Baker— Loose Aren aceou s Sedimen ts .

made glass stoppers, which are groun d so,as to fit well

,an d alway s

to en ter the tube to the same dep th . The stopp er carries two shorttubes

,to o n e o f which is attached the j et—tube an d to the o ther the

man ometer- tube,carry in g a graduated scale

,in ten ded fo r use with

a p articular j et . By havin g corresp ondin g pairs o f j ets an d

graduated man ometer—tubes,the same elutriator—tube may be used

rep eatedly in carry in g out differen t parts o f the mechan ical an aly sis .

In settin g up the apparatus fo r the first time a j et an d un graduatedman ometer—tube are attached

,an d the water turn ed o n . The flow

is co n tro lled by mean s o f the screw—clip on the fairly thick—walledrubber con n exio n attached to the lower en d o f the elutriator - tube .With the water standin g at some arbitrary p o in t low down in theman ometer- tube

,the outflow

,in cubic cen timetres p er‘

min utefrom the j et

,is determin ed by mean s of graduated measure an d

chron ometer . This p o in t is marked and the curren t then in creased,s o that the water stan ds at a higher p o in t in the man ometer - tube ,when a fresh determin atio n o f the outflow p er minute is made .Pro ce edin g in this way a series o f readin gs is obtain ed

,which when

pl o tted o n_a graph are found to lie o n a smo o th curve , by mean s o f

which theman ometer scale can be con structed . This scale,therefore ,

in dicates from the height of the water in the man ometer - tube , thevo lume in cubic cen timetres p erminute flowin g through the elutriatorwhen the app ropriate j et is bein g used .

A graph is con structed,showin g fo r each elutriator- tube in use the

relatio n between the rate of outflow from the j et , in cubic cen timetrespe r minute , an d the mean rate o f the upward curren t in the tubein millimetres p er secon d . The graphs fo r all the tubes can be conven ien tly represen ted o n the same diagram— they are

,o f course ,

straight l in es .

In pro ceedin g to make a separatio n o f a samp le at some sp ecifiedlimit o f diameter, the first step is to take the temp erature o f thewater which is to be used . Kn owin g this, the appropriate. rate o fcurren t is n ext ascertain ed . Then

,o n con sultin g the graph for the

elutriator - tube which it is propo sed to use,the rate o f' .outflow from

the j et re quired to give this curren t is readily obtain ed . It then . o n lyremain s to . select a suitable j et an d corresp o n din g graduatedman ometer—tube for attachmen t to the apparatus .

The separation o f'

a sedimen t in to a large n umber o f grades is a

tedious busin ess, an d much valuable time is o ften lo st in removin gfrom the elutriator,dry in g , an d weighin g the successive remain dersas grade after grade iswashed o ff the samp le . In o rder to facilitatethe pro gress o f the an alysis the writer has devised the fo llowin gmethod? o f p ro cedure which obviates the n ecessity o f removin g an d

dry in g'the material at the comp letio n o f each stage o f the pro cess .

It is n ecessary to kn ow[

at the outset the weight of the emptyelutriato r- tub e together with its rubber con n exio n an d screw - c lipat the bo ttom,

but without the stopp er'

an d its adjun cts . A weighin gis taken befo re the elutriatio n is commen ced,

o f tube and co n ten ts ,

H . A . Baker— Loose A r en aceous Sedimen ts . 331

when the samp le is in the tube .an d the remain der o f the tube is filledwith water up to the level to which the bo ttom o f the stopp erreaches . The weighin g can con ven ien tly be o btain ed by mean s o f

a large Sp ecific gravity balan ce havin g on e of the pan s at a higherlevel than the o ther an d equipp ed with a ho ok un dern eath . Afterthe elutriation an o ther weighin g of tube an d con ten ts is taken

,an d

the n ext stage in the an alysis can he p roceeded with immediately ,

whilst the weight o f sedimen t remain in g in the tube at the en d of theprevious stage is bein g calculated . This required weight is calculatedfrom a formula which is obtain ed as fo llowsBefore

{Let weight of sedimen t in tube a gms .

e lutriation Let weight of water in tube b

AfterjLet weight o f sedimen t in tube c

elutriatio n Let weight o f water in tube d

a is kn own when put in ,

'

an d to tal weight of con ten ts is found,hen ce b to tal weight con ten ts a .

The to tal weight 0 d - 1s foun d by weighin g .

Put c + d = x ; then d z x — c .

Now the total vo lume of sedimen t an d water remain s the same atthe end of the exp erimen t as it was at the begin n in g .

Put p ; den sity o f water used,an d

p2 den sity o f sedimen t .Take (treatin g the sedimen t as a pure quartz san d) .

Then vo lume before elutriation2 65

+17

1)c .u cm .

and vo lume after elutriation cu . cm .

p ].

a b

2 65+p 1 2 65 p l

i . e . ap l 2 656 Cp l 2 - 65d,a nd substitutin g a; c for d

,we get

an1 2 656 : cp l 2 6590 2 - 650 .

p l

. The formula gives very good results,sin ce a , x ,

an d b are all

d etermin ed by weighin g , an d the error invo lved by takin g the den sityo f the sedimen t as is very small

,sin ce aren aceous sedimen ts are

very largely quartzo se . For the value of p l appropriate to thet emp erature o f the water at the time o f the exp erimen t, it is . co n

v en ien t to con sult a graph showin g the variatio n o f the den sity of

the water in use with chan ge o f temp erature This graph can be«con structed from the results of prelimin ary exp erimen ts o n theWater .

It may be remarked, however, that an error in the determin ation o f

P1 co n siderably . greater than the exp erimen ter is likely to make inp ractice, in troduces o n ly an in sign ifican t error in to the fin ale valuation of 0 . It i s well , however, to be as accurate as po ssibl e ,

332 H . A . Baker— Lo ose A r en aceous Sedimen ts .

sin ce errors in the determin ation o f c are accumulative the c of on estage o f the an alysis

'

be comin g the a o f“ the n ext .

In the earlier stages o f an an alysis, when washin g o ff the veryfin est material , the method outlin ed above is n o t practicable . Widean d heavy tubes, such as can n o t be susp ended from the arm of a

laboratory balan ce, are usually then m use . Mo reover,much of the

material remo ved co n sists o f clay or lithomarge , hydrated silicate o falumin a

,an d con sequen tly the figure for its den sity is in ad

missible . The writer determin ed the mean den sities o f a n umber o f

Lower Tertiary san ds o f differen t typ es, an d foun d that in san d

co n tain in g a fair p ercen tage - weight o f the clay grade the averageden sity dro p p ed rather markedly . A quartz san d co n tain in g 4: p ercen t by weight of clay has an average den sity o f and the averageden sity decreases below thisfigure at about °

0015 for every 1 p er cen tweight in crease o f the clay grade . A quartz san d with 20 p er cen tby weight o f clay has an average d en sity o f 25 74 . The LowerTertiary san ds, when washed free from clay , had the same den sityas quartzAn o thermethod,

which avo ids lo ss o f time in the dry in g o f residues,is as fo llows : On the comp letio n of a stage of the elutriatio n processthe residue is run out from the tube in to a glass flask filled to a marko n the n eck with water . The weight o f water ‘

required to fill theflask to the mark is kn own . When the sedimen t is in the flaskthe water disp laced by it is removed

,so that the water stan ds at the

mark on ce more . A weighin g is then taken . The differen ce betweenweight o f sedimen t with water to mark an d weight o f water to markgives the weight of the sedimen t i n water . The weight of thissedimen t, when dry ,

1s then calculated from the fo rmula :

Weight (gms . ) Z

dx weight in water (gms . )

where d den sity of the material .As already stated,

if the clay material has been removed from thesamp le , the den sity o f aren aceous dep o sits may safely be taken as

2°

65 . The above fo rmula assumes the den sity of the water to be1 , but the erro r invo lved is n egligible in practice .This method is particularly useful when elutriatin g aren aceous

sedimen ts after the clay ey material has been removed . It is thenvery conven ien t to calculate the in itial weight of sedimen t from the

formula given above . If an in itial weight o f gm . be takenthis will weigh exactly 25 gm . m water

,and the successive weights

in water obtain ed afterwards have on ly to be multiplied by four ino rder to g ive p ercen tages .

(To be con tinued . )

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334 Revi ews— Diag n osti c Character i sti cs of IV] ar i n e Clastics .

DIAGNOSTIC CHARACTERISTICS OF MARINE CLASTICS . By E . M.

KINDLE . Bull . Geo l . So c America,vo l . xxviii, pp . 905—1 6 .

19 17 .

THE author o f this pap er is very deep ly

.

an d rightly impressedwith the truth Of’ the say in g that the p resen t is ,

the key to the

past ”a He therefore brin gs fo rward some of his Observation s of

phen omen a in presen t—day sedimen ts which may be of use in decidin gwhether ro cks are o f marin e or freshwater origin . The p o in tscon sidered are (1 ) the behaviour o f fin e sedimen t in fresh an d saltwater

, (2) the Surface markin gs an d textures develop ed durin gsedimen tatio n an d durin g desiccation o f muds

,an d (3) the

distin guishin g characters o f ripp le—marks . In the first p lace it isn o ticed that altern atin g lay ers o f san dy an d muddy materialdeposited in salt water have more sharp ly defin ed boun daries thanthese laid down l n fresh water

,owin g to the comparatively rapid

flocculation Of very fin e Sedimen t m salt water .

Passin g to the seco n d sectio n,it is exp lain ed that this flo cculatio n

o f clay is accompan ied by small vertical curren ts, an d that 'thesecause structures kn own as p it an d moun d structures o n thesurface o f the dep osit . Structures produced durin g desiccation are

also,differen t in freshwater an d salt - water

'

muds the sun cracksof salt—water muds have level or turn ed down edges, while the edgeso f the se

‘

cracks fo rmed in freshwater muds are turn ed up . Further,the texture of a dried salin e mud is vesicular, an d thus quite un likethat of a f reshwatermud . The questio n o f ripp le - marks is discussedat some len gth , an d the author draws distin ction s between tho se dueto curren t actio n an d tho se due to wave actio n without forwardmovemen t The fo rmer typ e will be foun d to p redomin ate in tidalseas

,while the latter 1s more prevalen t In in lan d lakes , it is also

n o ted that the ripp le - ma1ks produced by rivers will Show eviden ceo f mo tion in on e directio n o n ly , while tho se due to tidal curren tswill in dicate mo tion in at least two opp o s1te direction s . Though Inthe op in ion o f the reviewer the author app ears to be somewhat overn guin e , y et the p o in ts advan ced In this p ap er seem to be worthy

o f serious con sideratio n when wo rkin g through series o f sedimen tso f doubtful o rigin .

THE MINERAL DEPOSITS OF SOUTH AMERICA .( By B. L . MILLER

an d J . T . SINGEWALD , jun . pp . ix .+ 598,with 61 figures .

New York : McGraw - Hill Bo ok CO .

,In c . Lo n do n : Hill

Pub Ltd . 1919 . Price 258 .

WE co rdially welcome this 'bo ok,in asmuch as it gives us for ‘the

first time a co llected an d accessible accoun t o f the greatmin eralwealth of the South American Con tin en t, fromwhich came so mucho f the fabled wealth of the Span ish galleon s . The amoun t o f detailed

Revi ews— The Min era l Dep osi ts of South Amer i ca . 335

in formatio n con tain ed in these pages is aston ishin g , and thoughwritten in somewhat more prosaic sty le than the stories '

o f the earlyadven turers, it is equally in terestin g , p erhap s more so to an econ omicgeo logist, sin ce the roman ce is here foun ded o n fact .The first chap ter co n tain s an admirable descrip tio n o f the gen eral

phy siographical an d geo logical features’

of South'

America ,with a .

discussio n o f tecto n ics an d their bearin g on the problems of

mineralization . The coun try is divided in to eight districts— theGuian an Highlands , the Brazilian Highlands, the Co rdilleras, theLlan o s an d the p lain s of the Orin oco ,

the p lain s o f the Amazon ,

the plain s o f the Paraguay and Parana,the Patagon ian Pampas,

an d the coastal p lain s . Nearly all the econ omic min erals are

con tain ed In the first three .Each o f the succeedin g eleven chap ters con tains a full an d com

p rehen sive accoun t o f the econ omic geo logy of o n e o f the SouthAmerican States

,a large part of the in formation bein g the result of

p erson al observation s by the authors, especially in Brazil, Chile ,

Bo livia, and Peru,

an d In part in Argen tin a,Ecuador

,and Uruguay .

Each chap ter closes with an admirable bibliography ,Which 111 some

cases in clude over 200 items . This is an invaluable feature of thebo ok .

Amo n g s o man y p o in ts of in terest it is difficult to make a selectionfor sp ecial men tion . On e of the most fascin atin g chap ters is that o nBo livia

,where the rich Silver- tin - tun gsten min eralization n aturally

comes in for a large share of atten tion , bo th on accoun t of itsin trin sic value an d for its theoretical sign ifican ce . It is refreshin gto read a clear an d coheren t accoun t of these imp ortan t depo sitsas they really are

,freed from the absurd gen eralization s of the

Freiberg schoo l The Bo livian silver tin deposits seem to fo rm a

well authen ticated examp le of the o ccurren ce of tin an d tun gstenin quan tity in con n exi on with Tertiary ign eous activity . It isn o tewo rthy ,

however, that as so on as the fron tier o f Argen tin ais cro ssed the min era ls are clearly asso ciated with Palaeo zo icgran ites . Hen ce we have here an in stan ce of the o ccurren ce o f asimilar typ e “ o f min eralization in two n eighbourin g areas at two

widely separated p eriods of time . It is as y et to o . early to saydefin itely whether there is an y overlap o f these two min eralizatio n sin space .A very full accoun t is given o f the iro n an d man gan ese resources o f

Brazil ; the former are un doubtedly en ormous,

some go od

authorities havin g estimated the reserves o f haematite in the Stateo f Min as Geraes alo n e at 12 ton s . This is probablyexcessive , but it is clear that Brazil Co n tain s the mo st importan t .undeveloped dep o sits o f iron o re o f an y coun try in the wo rld .

However, developmen t 1s hindered by difficulties o f tran sp ort, owin glargely to the absen ce of imp o rtan t coalfie lds an d the remo ten ess o i

'

the iro n districts from the coast Themagn etite ores o f Jacup iran ga ,

described by Derby , are o f great petrographic in terest , sin ce they are

336 Revi ews— Minera l Resources of Gr ea t Br i ta in .

d erived from a highly alkalin e syen iticmagma . Man gan ese is n ow themost imp ortan t o f the min eral products o f Brazil , and in 1916 thep roductio n was n early half a millio n to n s

, mostly shipp ed to theUn ited States, rep lacin g supplies fo rmerly obtain ed from Indiaand Russia .

It Is Imp ossible in the space at our disp osal to men tio n even a

tithe of the in terestin g facts con n ected with the min eral wealth o fSouth America, bo th develop ed an d undevelop ed ; we can on lyadvise all geo logists who feel an y in terest in the eco n omic side o ftheir subj ect to read this bo ok , which is in disp en sable to the practicalman ,

an d con tain s a min e of in formation o f value to tho se dealin gwith the g eo logy o f all min eral products, metalliferous and n on

metalliferous, salts, coal, o il , an d gems .

R . H. RASTALL .

SPECIAL REPORTS ON THE MINERAL RESOURCES OF GREAT BRITAIN .

.VOL VI : REFRACTORY MATERIALS . 2n d edition . Mem . Geo l .Survey . pp . vi 241

,with 3 p lates and 8 text - figures . 1920 .

Price 78 . 6d. n et

HE first edition o f this memo ir, published in 19 17, was reviewed

at some len gth in this Magazin e , an d this edition do es n ot showman y chan ges a few small correctio n s have been made

,but in the

main the description s remain as before ; the fie ld - staff has beene n gaged on o ther work , an d n o re - examin atio n '

o f the min es and

quarries was foun d p ossible . We trust that this do es n ot mean thatthe vo lumes o f this mo st useful series will n ot be kep t up to dateby frequen t revisio n ,

as has been an ticipated . It is,however,

satisfacto ry to fin d that an o ther vo lume Is i n the press givin g thechemical an alyses, p etro lo gical descrip tion ,

an d results Of refractorytests o f the materials here described . This will addmuch to the valueof the presen t work .

EARTHQUAKES IN OREGON . By WARREN DUPRESMITH . Bulletino f the Seismo logical So ciety o f America,

vo l . ix,1919 , pp . 59—71 .

HOUGH sometimes supp o sed to be Immun e from earthquakes,the State of Orego n ,

as this short pap er shows,has been

disturbed by thirty earthquakes durin g about the last seven ty y ears,most of them slight , but amon g them were two stron g en ough todamage buildin gs “ The reco rds are

,however

,too scan ty to

b

leadto results of much scien tific value .

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IND IA N G EO LO G ICA L SURVEY

DEPA RTM ENT .

HE Secretary of State for In dia p rop oses to make four

app o in tmen ts to the In dian Geo logical Survey Departmen tin August this. y ear if so man y qualified can didates are available . Preferen ce will be g iven to candidates who have servedin His Maj esty ’

s Forces durin g the War. Besides a good gen eraleducation , a soun d education in geo logy is essen tial . A Un iversitydegree an d a kn owledge o f Fren ch or German will be regardedas imp ortan t qual ification s. Can didates should n ot be morethan 25 y ears of age , but this rule

_may be relaxed i n ex cep

tional cases . Detailed regulation s an d forms o f app l icationmay be obtain ed from the REVENUE SECRETARY,

In dia Office,London , S .W. I . Ap p lication s . for ap p o in tmen t must bereceived n o t later than l st August, 1 920 .

SC IENT IFIC BO O K S a n d SER IA LS .

JO HN WHELDON 0 0 . have th e l arg e st sto ck in th e coun try o f Bo oks in a l l

de p artme n ts o f Scie n ce an d Natura l Hi story . a l so T ran sactio n s an d Journ a l s o f L e arn ed

So cie tie s , e tc . , in se ts . run s . an d Si n g l e vo lum e s o r numbe rs .

Li b ra r ie s o r srn a l l Pa rc e ls Pu rc h a s e d .

SPECIAL CATALOGUES Ge o lo g ica l . Bo ta n ica l . Z o o lo g ica l , En tom o lo g ica l .

O rn itho l o g ica l , Che m ical , A g ricu l tura l , Garde n in g , e tc . , 2 d . e ach , p o st fre e .

38 GREAT'

QUEEN STREET , KINGSWAY,LONDON, w.c . 2 .

Te lep hon e : GERRARD 1412 .

Al l Commun icatio n s for the EDITOR should be addre ssed to

R. H. RASTALL, Esq. , M.A . , Christ’s Co ll eg e , Cambridg e .

All l etters for Dr . H . W'

OODWARD , m ay be sen t to

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Books an d Sp ecimen s to be addressed to the Editor as usua l, care of

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EDITED BY

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AND

'

R . H. RASTALL

ASSISTED BY

PROF . J:w . GREGORY , D . so F RS . Sm JETHRO J . H . TEALL , SC .D

F . H . HATCH , PHD , W .-SC. D . , F .R . S .

F .R . S . HENRY WOODS , M .A F .R . S .

DR . A . SMITH WOODVVARD , F .R . S .

AUGUST, 19 20 .

EDITORIAL NOTES

ORIGINAL ARTICLES.

Be erbachite at the Lizard . ByPro f . T . G . BONNEY , F.R . S .

Note s on the Faun a of the Lower

Devon ian Beds o f Torquay .

By F . R . COWPER REED . (Concluded . )

The Ge o logy o f Castl e - an - Din as

Wo l fram Min e . By E . H .

DAVISON , B . Sc . (With 2 Text REPORTS AND PROCEEDINGS .

Min eralog ical SocietyOn Jurassic Ammon ite s from East Geo l og ists

’ Associatio n . .

Africa , co l lected by Prof . J . W.

Gregory . By L . F.CORRESPONDENCE

(Co ncluded ) Pro fe ssorW . M, DavisIn ve stigation o f the Mechan ical W, B , WrightCon stitution o f Lo o se Arenaceous C , Carus -Wil so nSedimen ts by the me thod o f

Elutriation . By H . A . BAKER .OBITUARY

(With-

a Tex t- fig . ) (Contin ued ) 363 George Swe et

LONDON : DULAU 6: CO LTD . , 34—36 MARGARET STREET ,

CAVENDISH SQUARE , W . 1 .

Cl oth Cases for Bindin g may be had, price 28 . n et .

REVIEWS .

Echin o id o r Crin o id

Palaeo zo ic Til l ite s o f Northe rnN orwayThe Arbouin Min e s , Que en slan dThe Ke n t Coal fie ldThe Submerg ed Fore st at BombayThe Porto Rico Earthquake of 1 9 18Min eral s from Bihar an d OrissaArsen ic an d An timon y Ore s

JAMES SWIFT SON,Manufacture rs of Optica l and Scie ntif ic lnStrume n ts ,

Co n tracto rs to all Scie n tific De p artme n tso f H.M. Home

and Co lo n i a l and man y Fo re ig n Go ve rnme n ts .

Gra n ds Prix, Dip lomas of Hon our, an d Go ld

Me da ls at Lo n do n , Paris, Brusse ls , e tc.

IC RO S C O PESAND OTHER

INSTRUMENTS FO R

ALL BRANCHES or

GEO LOGY,

MINERALOGY,

PETRO LOGY.

So le Make rs o f the

DICK MlNERALoc L

Micnoscop ss .

Dr. A. HUTGHINSON'S

UNIVERSAL GONIOMETER.

U n iv e rs it y O p t ic a l

.

Wo rk s ,

81 TOTTENHAM COURT ROAD,

LO NDO N, W . 1

OSWALD (FELIX) , D . Sc . , A Ge o lo g ica l Map _

O f theCaucasus . With exp lan atory text. Comp il ed from the late st

source s . 15s . The g eo log ical

formation s an d the ign e ous ro cks are cl e arly disp lay ed in twen tydifferen t co lours . The g laciers are al so in dicated . Al l he ig hts are

g iven in En g lish fe et, an d the late st railway s have be en in serted .

The p amp hle t o f exp lan atory text g ive s a brief accoun t o f the main

p hy sical division s o f the Caucasus , fo l lowed by a detailed de scrip tio n

o f the succe ssive g e o log ical hori zon s W ith th e ir characteristic fo ssil s .

Sp e cial care has be en taken to in dicate the exact p o sition in the

g eo log ical series at which p etro leum o ccurs in the Caucasian

o il - fi elds .

J US T IS S UED . .

CATALOGUEOFZOOLOGICAI. WORKSch iefly Orn itho logy ay d En tomo logy .

OFFERED ron SALE av

DU LA U 8< C O . , LTD .

(E S TA BLIS HED l 7 9 2 )

34—36 Margare t Stre e t, Cave n dish Square , Lo n do n ,W. 1 .

L IER A R IE S P U R C HA S E D IN T O W N O R C O UN T RY.

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5338 Edi tor ia l No les .

WE have received from the Yo rkshire Ge o logical So ciety a circularsettin g forth that the So ciety is an xious to develo p the study o f

Yo rkshire rivers alo n g the lin es that have p roved so fruitful inAmerl ca With their customary en terp rise the Coun cil hav eformulated a comprehen sive scheme fo r which they desire toen list the aid o f wo rkers in al l co gn ate scien ces , whether memberso f the So ciety o r n ot . As a matter o f fact the wo rk was begun inthe Washburn valley last summer, an d will be co n tinued there ,but it is hop ed to exten d it to o ther rivers throughout the coun ty .

The circular very wisely p o in ts out that a precise kn owledge o ftecto n ic structure is o f fun damen tal imp o rtan ce in such a study ,

sin ce this must affect the o rigin an d evo lution o f the -

rivers hen cewo rkers are in vited in the first in stan ce to reco rd - with precisio nthe dip o f the ro cks in ’ their respective areas . This is n ot quiteso easy as it soun ds at first

,as all fie ld - wo rkers are well aware

,

owin g to landslip s , surface—creep ,curren t - beddin g , an d o ther

causes which n eed n o t be specified here . The imp ortan ce o f a

record o f faults an d domin an t j o in ts is also in sisted on . Besidesthese purely geo lo gica l p o in ts , in fo rmatio n is also desirable as torecords o f rain fall an d the heights attain ed by fl o ods an d theirfrequen cy . Recen t exp erien ces in Lin co ln shire have demo n stratedthe geo lo gical po ten cy o f sudden floods . With regard to the actualcarry i n g out o f the wo rk , it is pro p o sed wherever p o ssible , to fo rmlo cal committees , an d all tho se in terested are in vited to com

mun icate with the Secretary ,Mr H . E . Wro o t

,Po llard Lan e,

Bradford .

THE Governmen t has n ow 1n troduced in to Parliamen t thep romised Bil l for the establishmen t of a Min istry o f Min es, an d,fran kly ,

it is a very disapp o in tin g documen t . It is a good p o in t,in view of econ omy , that the Min istry is to be a Departmen t of theBoard o f Trade an d n ot en tirely new an d in dep en den t , but bey on dthis we fin d little to p raise . The p rovision s o f the Bill are almosten tirely con cern ed with coal - min in g , an d n on - ferrous min in g is

on ly on ce sp ecifical ly men tion ed . It is p rovided that the Min istersha l l ap p o in t a committee to advise him regardin g coal , an d thathe may ap p o in t a similar on e to deal with other m in es an d

quarries . We must hop e that the metalliferous min in g industrywil l make its n eeds kn own with sufficien t force in the p rop erquarters, so that more con sideration may be shown to an

imp ortan t in dustry by the Act in its fin al shap e .

ORIGINAL ARTICLES.

Be e rbachite at the Liz ard.

By Professor T . G. B‘

ONNEY,Sc .D . , F.R .S.

N my pap er on the Lizard this rock is men tion ed, but withouta sp ecific n ame

,for I had n ot then seen the figure given in

1898 by Ro sen busch'

(Elemen te cl erGestein slehre , 1898, p . He callsit Beerbachite

,an d describes it o n p . 219 as o n e of his Ganggestez

’

n e,

amo n g those e on malckitl sckem Hccbfzflus , quo tin g an an alysis . Then ame appears to have been given by Che lius to a ro ck from Fran kenstein in the n orthern Odenwald,

where it "

forms small vein s in a

gabbro ,an d has the fo llowin g an alysis SiO2

2 A120 3Fe 20 3 FeO 2 MgO CaO Na20

K2O HQO P20 5 2 0 46, with FeS2 an d

0 10 hygro scop ic water . He states that the rock is fin e—grain ed tocompact, n ot lustrous, grey to pale grey in co lour

,con sisti n g o f a

pan idiomorphic mixture o f labradorite and diallage , with a variableamoun t o f hyp ersthen

' e and_

magn etite , an d that o livin e bearin gvarieties o ccur . In these common ly a brown horn blen de rep lace sthe diallage , .

in which the above n amed con stituen ts are p oecilitic .

He states that beerbachite also o ccurs in gabbro n ear Harpburg an d

in the Isle o f Mull .At the Lizard the best outcrops o f the ro ck are n ear Luggar

Cove,to the south of Porthousto ck

,an d I call it in my diary for

July 6, 1894, when I particularly studied that part o f the coast ,the brown - sp eckled rock

,

”

but it o ccurs,sometimes in con siderable

force , from n ear St . Kevern e to the n eighbourho od o f Porthallow,

1

an d I observed an d co llected it,a few y ears earlier, from the crags

n orth o f the Balk where , however, it is less well exp o sed an d rathermore weathered . The fo llowin g shorten ed extract from my diary fo r1894 (which is illustrated by sketches) may serve to show the ”

curiousmixture o f ro cks n ear the sho re to the n orth o f Creusa Down . In

certain p laces . the gabbro itself varies much , a coarse variety ,with

diallage crystals sometimesa coup le o f in ches in diameter, occasion allyapp earin g in irregular patches and even in little ton gues in the finergabbro . The “ brown - sp eckled ro ck breaks in to the gabbro ,

in cludin g fragmen ts, patches, an d streaks of it,a few in ches or even

more in len gth an d p erhap s on e to three 1n diameter, which oftenassume a fo liated structure . The sp eckled ro ck also n ot seldomapp ears to

' be p orphyritic . The crystals which may run to about1 I studied the coast n orth of Crousa Down , from St . Kevern e , in 1890 , with

my frie n ds Gen eral McMahon an d Can on Hil l , an d_

again in 1894 with thelatter . I revi sited it in 1908 , when stay in g with Dr . Flett at Ken n ack Cove ,

to discuss sun dry p o in ts on which we were n o t agre ed , but do n o t remembe r

that we used then the word be erbach ite ;an d have sin ce se en a l ittle o f the

n e ighbourhood in 1 909 an d 1 91 2 .

340 Prof. T. G. Bon n ey -

fBee frbachi te at the Lizard.

half an in ch in len gth, are dead white like tho se in the gabbro ,and often o ccur in scattered coveys Occasion ally they are

j o in ed,an d in clude a small crystal o f diallage, so they become difficult

to distin guish from the smaller gabbro fragmen ts . In fact,it lo oks

as if the brown - speckled ro ck had o ccasion ally p artly melteddown bits of the gabbro ,

destroy in g the augite rather than thefelspar

,and had soften ed and drawn out o ther patches, so that

a pro cess an alogo us to what Pro fesso r So llas has described in theCarlin gfo rd gran ites has happ en ed here ” . Dykes o f a compactgreen ston e out both these rocks, but are n either abun dan t n orthick ; seldom

,I thin k , mo re than 4 o r 5 feet . 1 All alon g the

coast to n orth of Porthoustock~we fin d (1 ) gabbro (the domin an trock) , (2) n ext to it the brown - sp eckled then (3) the green ston e ,much less abundan t . So there is n o justification for co lourin g all

this part gg reen sto n e , as i n the Survey Map . But I thin k the beer

bachite at the Lizard must o ccur i n rather thicker masses than itseems to do i n German y . Un der the micro scop e my best slices o f

beerbachite (I have about seven in all ) con tain a rather stron glyp leo chro ic horn blen de, pale to rich brown

,in hyp idiomorphl c grain s,

an d of rather stumpy form,together with a granular augite more

irregular in outlin e . The felspar (labrado rite ) , also gran ular in out

lin e , is in go od preservation ,and so is the iro n - oxide , which o ccurs

in rather small but irregular, rather numerous grain s . I can n o tcertain ly iden tify hypersthen e or aegirin e . Occasion ally the felsparof the beerbachite becomes rather elo n gated,

an d the horn blen deless granular close to a jun ctio n with the gabbro . On e slice distin ctlyshows the partial meltin g together o f the two rocks . Thoughit do es n ot app ear to have - an y marked chemical differen ce fromseveral o ther green ston es ” 2 it seems to be so p ersisten t in its

structure an d to exhibit such m in eral p eculiarities , that we must,I think , add beerbachite to the cry stallin e rocks of the Lizard,

as has

been already don e by Dr . Flett in The Geology of the Lizard and

Men eage where it is described briefly on p . 110 and a figuregiven at p . 101 .

j

1 The se , as a rule , are n otwe lded to the gabbro , be erbach ite , o r serpen tin e , as

the trokto l ite is to the last- n amed , so I regard the be e rbach ite as the fo rerun n er

o f the '

gre en ston e (basal tic) dykes so common on the eastern . coast o f the

Lizard.

2 Se e the an a lysisquoted in Ro se n busch ’s '

Gesz‘

e in slehre an d Fle tt Hil l ’sGeo logy of the L izard , etc .

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342 F. R. Cowp er Reed

and o f a n on - an nulated smo o th posterior p art bey on d the base o fthe seventh pair o f lateral

_ p leurae, which is imp erfect an d on ly10 mm . in len gth , but seems to have measured about 20 mm . Thereis a pair o f smal l tubercles or sp in es on the first axial rin g , an d alsoon the third

,fourth

,fifth

,an d sixth , an d p ossibly o n the seven th

,

but n o t on the o ther rin gs . The articulatin g half rin g at the fron te n d o f the axis is marked o ff by a stron g furrow,

which is con tinuedon to the lateral lobe, so as -to separate o ff a large trian gulararticulatin g surface from the first p leura . The p leural lobe, whichis p erfect, shows seven p leurae, but the seven th (

o n e,is very small .

The ‘

p leurae are broad, low,an d flatten ed

,an d the first on e carries

a large low tubercle at about half its len gth (or rather more) , whilethe fourth p leura has a similar tubercle at about on e - third its len gth ,thus resemblin g H. bifurcatas . The o ther p leurae are smoo th . Thereis a smo o th border o f regular width roun d the pygi dium ,

for thein terp leural furrows do n ot reach the margin . The o ther smallersp ecimen has the same gen eral characters , but seems somewhatmore elon gated,

and there are n o tubercles visible on the p leuraeo r axis

, but this may be due to immaturity or to individualvariation

,if we con sider that Clarke 1 has made out his case fo r

a similar variation in the allied tuberculated sp ecies, H. Herscheli'

Murch .

An imperfect glabella from New Cut, in the Sedgwick Museum(S. measurin g about 20 mm . in len gth , shows the lateral tuberclesan d the an terior median o n e , but the posterior part of the glabellais missin g, an d n othin g o f imp ortan ce can be added to Wo odward’

s

descrip tio n . There is,however, an in terestin g thoracic rin g (S. 4)

from the same lo cality an d in the same co llectio n which retain son e of the pair o f sp in es on the axis in an un broken con ditiona most un usual circumstan ce . The width o f the axis in this sp ecimenis 38 to the dimen sion s o f the o n e p erfect side ,an d the distan ce between the sp in es at their base is 22 mm . Thecomplete sp in e rises up sudden ly from the surface , an d is directedobliquely outwards ; it is straight , cy lin drical , an d slen der, tap erin gregularly to a sharp p o in t, an d its len gth is 18 mm .

An o ther tho racic rin g .(S. 4a) , with the axial sp in es 32 mm . apart ,from the same lo cality an d in the same co llection

,shows clearly the

broad,flat articulatin g ban d on the fro n t edge , n early as broad in

the middle as the rin g itself, but n ear the axial furrow or con strictiondecreasin g slightly in width . The stro n g , sharp ly impressed gro ovewhich marks it o ff from the rin g is con tinued o n to the p leura o n

each side so as to become the p leural furrow . The outer p ortion an d

tip o f one p leura (S. 7) from the left side o f the thorax shows thisso - called p leural furrow well . This p leura has a flatten ed an d ratherrapidly broaden ed subspatulate extremity ,

with the an terior edge

1 Clarke ,Foss. Dev. Paran a (Mon . Serv . Ge o l . Min e r. Brasil ), vo l . 1, p . 93,

p l . i ii, figs . 1—4 .

Faun a of the Lower Devon ian Beds of Torquay . 343

of the p leura straight -

_

o r slightly con cave , and the p leuralfurrow,

which is n earer to it than to the p o sterio r edge , is subparalleland dies out some distan ce before reachin g the subtrun cate roun dedtip . The p osterior edge o f the p leura is stro n gly arched backwards ,makin g a con vex curve

,an d at the p osterior outer an gle o f the

tip bears a small but distin ct margin al tubercle , which seems to beun ique .The relation s of H. Champ ern own e

'

i to H. armatas Burm . werebriefly discussed by Wo odward in 1881 . We may here especiallydraw atten tion to the close resemblan ce o f the pygidium in theTo rquay Museum to on e o f those figured by Ko ch ,1 under the n amearmatas, but the n umber an d p osition o f the sp in es on the axis o f

H. Champ em own ei are distin ctive features . Wo odward also com

men ted o n its resemblan ce to H. e longatus Salter, an d this is speciallyworthy o f n o te

,though on ly the pygidium of the latter is kn own

with certain ty . But,as I have p o in ted out in my paper on the

classification o f the gen us,2 we can n ot strictly refer it to the samegroup as H. Herscheli

,though Wo odward r egarded the latter as

o n e of the two n earest allied sp ecies .

H RedHomalon o tus Beds Li n combe an dWarberryGrits Staddon Grits) .3Locality

— New Cut Lin combe Drive) , Torquay . (S. 8 ,4 G), 7 T A

2?)

Homalon otus (Burmeisterella) e longatus, Salter .

1865 . Homalon otus (B-urmeisteria) e lon gatus Salter, Mon . Brit. Trilo b. , p . 122,

p l . x, figs . 1,2 .

19 18 . Homalon otus (Burmeisterel la ) elon gal

tus Re ed, GEOL. MAG ., p p . 314, 325 .

The pygidium on which this species was foun ded was sufficien tlydescribed by Salter (op .

The species has been chosen by the presen t author as the typeo f his n ew subgenus Burme istere lla (op . cit . supra) , an d its

affin ities have been discussed . It is un fortun ate that n o '

furtherexamples of the sp ecies have been reco gn ized,

an d that we areign oran t o f the thorax and head- shield

, though apparen tly Salterbelieved that the fragmen ts figured by Phillip s 4 belon ged to it . But

this con clusion seems to me,

to”be extremely doubtful after a careful

examin ation o f the actual sp ecimen s in the Jermvn Stre et'

Museum .

(3 9

(233

Locality— Meadfo ot

,Torquay .

Horizon r—Meadfo ot Beds .

1 Ko ch , op . e l t t . i,figs . 3, 3a .

2 Re ed , GEOL . MAG 19 18 , pp . 314 , 324 , 325 .

3 Usshe r, Mem . Ge o ] . Surv Exp lan . She et 350,1903, p . 35 .

4 Phi llip s, Palaeo z . Foss . Cornw . Devo n,184 1 , p . 130 , p l . lvii , figs . 253a—e

(H. Kn ighti figs . 253a—c ; H. Herscheli fig . 253d) .

344 F. R. Cowp er Reed

Homalon -otus (Burme istere lla) armatas (Burmeister)1843. Homalon otus armatus Burme ister, Organ . Tri lob . , p . 102 , p l . iv,

fig . 1 .

1883. Homalon otus armata s Ko ch , Abh . Ge o l . Sp e c . Kart . Preuss . , iv,2,

p p . 124 7, t . i , figs . 1—6 .

1909 . Homa lon otus (Burmeisteria ) armatas Gurich , Le itfossi lie n , Lief. ii,

De vo n , p . 156, t . xlvi i i,fig . 2 .

It is doubtful if this species r'eally o ccurs in En gland, but the

material from Meadfo ot is to o p o or to decide the questio n .

Fragmen tary tho racic rin gs an d portio n s o f the pygidium from

the tough brown ish sandstone o f Me adfo ot which are preservedin the Sedgwick Museum (S. 5) appear to po ssess the charactersdescribed an d figured by Koch (op . cit ) . They seem certain lydistin ct from H. Champ em own ei o f the red argillaceous beds o f

the New Cut .

Horizon .

-Meadfo ot Beds (s an dsto n e):Locality .

—Meadfo ot, Torquay (S.

Homalo -n otus (Burmeistere lla) sp .

There is in the Sedgwick Museum on e left free cheek,somewhat

distorted, from the New Cut,To rquay ,

which has the p eculiarityo f the border bein g raised an d sharply bevelled so as to form an

an gulated edge . In this resp ect it agrees with the cheek figured byDreverman n

1as Homalon otus sp . from the Lower Coblen zian o f

Oberstadtfeld,an d in describin g it this author remarks that the

p o ssessio n o f this border separates it from all o ther sp ecies o f thegenus . In our sp ecimen ,

which is comp lete excep t for the p o steriormargin , the gen eral surface o f the cheek is swo llen and elevated n earthe ey e but sin ks down in to a broad con cen tric submargin al co n cavitywhich rises to the sharp ly an gular in n er edge o f the border ; thelatter in creases in width to the gen al an gle, an d has a bevelled outerface . There is the base o f a large ," stout, roun ded sp in e or tuberclen ear the in n er edge o f the swo llen p o rtion of the cheek, as in

Dreverman n’

s figure . A more quadrate less p erfect free cheek fromthe same lo cality at Torquay is also preserved in the SedgwickMuseum

,an d resembles the o ther figure (fig . 1 ) given by ‘Dreverman n

o f this un determin ed sp ecies . The presen ce o f the spin e~base o n

the cheek suggests that it belon gs to the subgenus Burmeistere lla,and pro bably o n e o f the sp ec1es above described should receive it .Horizon — Red Beds (Staddon Grits) .Local

'

ity .

—New Cut, Torquay (S. 9 ,

Homalon otus (Parahomalon otus) Whidhorn ei sp . n ov . (Pl . IV, Fig .

Defin ition .

—Gen eral shap e elo n gated,flatten ed trilobation

n early obso lete . Head - shield short,broadly subtrian gular, trun cated

in fro n t in middle (with a small median epistomal p o in t pro j ectin gbelow l ) . Ep istomal sutures on upp er surface of head - shield

1 Dreverman n,Pa lwon tographica, xlix, 1902 , p . 74

, t. ix, figs . 1 , 2, 3

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346 F. R . 0 . Reed— Faun a of L. Devo n ian of Torquay .

it is difficult to make out the characters of the fron t of the headshield

,the left - han d s ide o f which is missin g as well as the greater

part o f the free cheek an d lateral margin of the right side . The en dsof the thoracic p leura? are also broken o ff

,and the lateral lobes

o f the pygidium are n o t preserved . The who le sp ecimen has alsobeen fl atten ed out by pressure , but it seems that it n aturallyp o ssessed an almo st comp lete absen ce of tran sverse convexity ,

and that the trilobation was in distin ct or n early obso lete . Theaffin ities of the species seem to lie with that group o f sp ecies of thesubgenus Parahomalon otus 1 which comprises H. lann

'

cauda Quen st . ,

2

H. p lanus Sandb .

,an d H. obtasas San db .

,as defin ed by Ko ch

(op . The pygidium from the Hauptquartzit figured byKayser 3 as H. multicostatn s Ko ch

,app ears to bear a clo se

resemblan ce to our specimen .

Dalman ites (Asterop yge ) lacin iatus (Ro emer)1844 . Cryphoe us lacin iatus F. Ro emer Rhe in . Uebergan gsgeb . , p . 82

,t. ii ,

1 0 . 8 .

1889 . 1y nhco

e as laciniatus Kay se r, Abh. k . p reuss , g e o l . Lan desan st ,N.F

Heft i , p . 88,t . xxiv, figs . 1 9

In the Sedgwick Museum there is the impression o f the left halfan d posterior en d o f a somewhat distorted py gidium (S. 1 ) from theRed Beds of the New Cut

,To rquay ,

which'

precise ly agrees withKay ser’s defin ition and figures o f the common form o f Cryphoeus

lacin iatus Ro em .,from Daleiden . The five lateral sp in es an d the

much broader,but sho rter

,flatten ed, sublan ceo latemedian p o sterior

sp in e are well seen , though the first lateral sp in e is almost en tirelybroken o ff in our specimen . An o ther smaller example in the sameco llectio n an d from the same lo cality has lo st the first two sp in eso n the left side , but shows the who le p o sterio r part of the pygidium,

in cludin g the lateral lobe and last sp in e o f the right side . Thecharacters o f the axis and p leurae agree with Kayser’s defin ition .

There is also on e fairly well preserved head shield (S. in theSedgwick Museum,

likewise from New Cut, showin g the ey es,glabella ,

an d part o f the right cheek , and an other left free cheek(somewhat crushed) , with the gen al sp in e attached . The n umberof rows o f len ses in the ey e in this sp ecimen is about 27 an d n on e ofthe rows app ear to co n sist o f more than eight len ses . Thesefragmen ts o f the head—shield do n o t differ from Kayser’s descriptiono f the common fo rm o f the sp ecies , but much co n fusion has arisenfrom the differen t app lication s o f the sp ecific n ame lacin iatus, so

that it i s n ecessary to l imit the syn o n ymy which is frequen tly given .

Probably the trilobite from Torquay , which Salter 4 termed Phacop s(Cryp ltcen s) p an ctatus (Stein ) , should be referred to this species,but o n the o ther han d the sp ecimen s from Liskeard which he figured

1 Re ed , GEOL . MAG . 19 18 , p . 326.

Koch o p . ci t. p . 55 , t . vi i i , figs . 1—7 .

Kay ser, Abhan dl . ge o l . p reuss . Lan desan st ,N.F. , i , 1889 , p . 80,t. x i , fig .

0

4 Salte r, Mon . Brit Trilob .,1864 , p . 59 .

E . H. Daviso’

n — Castle - an - Di n as Wo lfram Mi n e .

un der this n ame seem to belon g to Kayser’s sp ecies Lethceae.

1

The form from North Devon which Whidbo rn e 2described as

Dalman ites (Cryp hceus) lacin iatus var . occidentalis is quite distin ctfrom our Torquay sp ecimen s . The use o f the subgen eric n ameAsterop yge in p lace o f Cryp hoeus is here adopted .

3

Dimen sion s .

—Pygiclinm (S. len gth , (I ) c. 17 mm .

, (11) c. 9 mm .

width (I) c. 20 mm .

, (II ) c. 1 1 mm . Head- shie ld (S. len gth8 mm . ; width , 0 . 18 mm .

Horizon — Red Beds (Staddon Grits) .Locality

—N ew Cut,Torquay (S. 1

,

Beyrichia (Z ygobeyrichia) devon ica (Jo n es 85 Wo odward) .1889 . Beyrichia devon ica Jon es Wo odward , GEOI MAG. , p . 386

,PI. IX

Figs . 3a - 3d (24,19 16 . Z yyobeyrichia devo n ica Ulrich , Prof. Pap er 89 , U S. Ge o l . Surv. , p . 29 1 ,

p l . xxvii , figs . 1—6 .

The sp ecies Beyrichia devon ica,which was first described by Jon es

an d Wo odward from the New Cut, Torquay , has been recen tlyrecorded from the Chapman San dston e (Lower Devon ian ) o fMain eby Ulrich (

'

op . who selects it as the typ e of a n ew genus, whichhe calls Z ygobeyrichia, characterized by the partial or completeobso lescen ce of the posterior lobe an d by the excessive developmen to f the ven tral jun ction o f the median an d an terior lobes Itmay be question ed whether this should n ot den o te subgen eric ratherthan gen eric ran k . The type - sp ecimen s o f the species are in theSedgwick Museum .

Horizon —Red Beds (Staddon Grits) .Locality .

—New Cut, Torquay . (S.

EXPLANATION or PLATE'

1v.

FIG. 1 .— Homalon otus (Burmeistere lla ) bifurcatus sp . n ov . Head - shie ld . x 14.

Staddo n Grits New Cut,Lin combe Drive , To rquay . (Sedgwick Museum . )

FIG. 2 .—Ditto Pyg idium of same sp e cime n . x 15. (Sedgwick Museum . )

FIG. 3,— Ditto . Imp ression of same pygidium , showin g te rmin al Sp in es .

x 14. (Sedgwick Muse um . )FIG . 4 .

— Homa lon otus (Parahoma lon otus ) Whidborn ei sp . n ov . Nat. size .

Me adfo o t Beds : fie ld at back of K ilmorie,n e ar Hop e

'

s Nose , Torquay .

(To rquay Museum. )

On the Ge o lo gy o f Castle - e u - Din as Wo lfram Min e .

By E . H. DAVISON ,B.Sc .

HERE are two hills n amed Castle - an —Din as in West Cornwall ,on e n ear Pen zan ce an d the o n e o n which the Wo lfram Min e is

situated,which lies about 2 miles east o f St . Co lumb Maj or an d

ab out 4 miles to the n orth o f the St . Austell gran ite mass .

1 Kay se r, op . cit. , p . 86, t . x i , figs . 5 6 .

2 Whidborn e , Quart . Journ . Ge o l . Soc . , vo l . lviii , 1897, p . 445, p l . x x x u i ,

fig s . 9—13.

3 Reed, GEOI . MAG 1905, pp . 173, 225 .

348 E . H. Davi son — C’astle - an - Di n as Wo lfram Mi n e .

The hill rises ‘

700 feet above sea - level,an d forms a con sp icuous

feature in the lan dscape ; it is surmoun ted by an an cien t earthwo rkwhich has given the hill its n ame . In 19 15 the outcro p of a lodewas tr

o

aced on the n orthern slop e of the hill , and this has beendevelop ed by min in g operation s and y ields a remarkably cleanwo lfram ore .

GEOLOGICAL STRUCTURE OF THE DISTRICT .

In a paper read before the Royal Geo logical So ciety of Cornwall 1the writer described the gen eral geo logy o f the district , but sin cethen the developmen t o f the min e has been carried further an d

fresh light has been thrown on the geo logical structure of Castlean - Din as hill .

INDEX

MEADFo o TS LA T E .

GRANITE.

LO O E

S CALE.

c

l ,

FIG . 1 .

— Sketch - map o f Castl e - an - Din as .

The hill is main ly built o f Meadfo ot Slates, which strikeapproximately east an d west, an d are fo lded on

“

axes roughlyparallel to the strike . The hill lies within the metamorphic aureo leo f the gran ite , an d the. slates“ have in addition been subj ected toin ten se pn eumato lytic alteratio n

,as a result of which, the con tact

min erals have been almost comp letely destroy ed ; in on e case ,however, the slates were seen to co n tain wo llaston ite .

1 The Geo l ogy o f Castle - an - Din as an d Belowda Beaco n Proc . B .G . S .

Corn .

, vo l . x ix .

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350 E. H; Davi son — C’astle - an - Di n as Wo lfram MW .

0

in in sign ifican t amoun ts . There is almost comp lete absen ce of tin ,

the ore con cen trates con tain in g less than 0 3p er cen t . The coun tryro ck, on the o ther han d, is seen un der the micro scop e to con taincassiterite, and samp les taken from the slate in .

the n eighbourho odof the gran ite have been assay ed an d found to con tain as much as1 p er cen t . These values are , however, to o in co n sisten t to have an yeco n omic imp ortan ce . An o ther remarkable character 1s the absen ceo f tourmalin e In the lode material

,while the coun try ro ck i s highly

tourmalin ized .

Towards the far en d of the upp er level the eastern wall is formedo f a gran itic ro ck much decomp o sed,

formin g white or p in k clayen clo sin g p artly decomp o sed felspar fragmen ts, quartz , fl akeso f white mica ,

an d n eedles o f tourmalin e . There are also harderban ds of greisen compo sed of quartz

, pale brown mica,which

con tain s lithia an d is very stron gly birefrin gen t , an d topaz , withgrain s an d n eedles o f tourmalin e .In ,the lower level at the po in t in dicated In the section (Fig . 2)

gran ite app eared l n the flo o r of the lode In the form of a soft clay ,

co n tain in g grain s o f quartz and flakes o f muscovite . This ro seslowly towards the '

so'

uth,and passed in to a hard fin e -

grain edgran ite , which exten ded above the ro of o f the level . On drivin ga cro ss - cutwest, the base o f the gran ite was seen in the flo or whereit was un derlain by clay slate

, an d o n con tin uin g the level to thesouth the slate again app eared above the gran ite, the surface o fthe latter con tinuin g with un dulatio n s . A win ze has been sun k120 yards n orth o f the po in t where the gran ite first app ears, butthough driven to a dep th of 87 feet n o gran ite was met with . Thesefacts p o in t to the gran ite havin g an irregular to n gue l—ike fo rm ratherthan to its bein g a p ortio n of

3

the main mass .

Developmen t is n ot sufficien tly advan ced to show if the lodecon tin ues down in to the gran ite, but there are irregular patches of

quartz with wo lfram in the gran ite ton gues, an d it seems probablethat the lode fissure was o n ly deflected by the presen ce o f theharder ro ck . It do es n o t

,however

,fo llow that the lode - filling

main tain s the same character .

The in timate way in which the gran ite p en etrated the clay - slatecan be seen in sp ecimen s of clay - slate co llected from p o in ts in thelevels where n o gran ite is in sight these are seen to be traversedby fin e vein s of gran itic material which cut across the fo liatio nan d vary from an in ch or so to less than on e - sixteen th of an in ch inwidth . Un der the micro scop e these fin e vein s are seen to con sist o fclear quartz , pale brown ,

highly birefrin gen t mica an d tourmalin e ,with o ccasio n al grain s o f cassiterite .The Castle - an - Din as lode is almo st un ique in character when

compared with o ther lodes o f West Cornwall . It is characterizedby the fo llowin g po in ts1 . The absen ce of pn eumato ly tic min erals such as tourmalin e ,

fluorspar, and topaz from the lode con ten ts .

L.

'

F. Sp ath— Jurassi c Ammon i tes from East

“

Af r i ca . 351

2 . The absen ce of sulphides an d the very small prop o rtio n o f

cassiterite presen t .3. The remarkably coarse texture Of the lode - fillin g .

The vein s of the Kit Hill Min e,Callin gton ,

are in some resp ectssimilar in character

,but they differ in con tain in g cassiterite

,

tourmalin e,an d mi sp ickel ; they also o ccur just below the surface of

the gran ite an d n ot in the clay - slate . There is also some similarityin the vein s o f the Hemerdon Hill sto ckwork, which are like tho seof

‘KitHill,with a much smaller prop ortion '

o f misp ickel in the vein s ,which also con tain sco rodite . There is again a similar vein ston e inthe middle lode of the recen tly reop en ed Killifreth Min e, St . Day ,

in which coarse patches o f wo lfram o ccur in cl ear quartz,which is

also traversed by vein s carryin g cassiterite , blen de, an d mispickel .The Castle - an - Din as lode seems to represen t the results of min eral

dep osition in the upp er part of the tin an d tun gsten zo n e , thesequen ce o f even ts havin g been somewhat as fo llows1 . Fo ldin g an d cleavin g of the clay slate .2 . In trusio n o f gran ite fo llowed by pn eumato lytic action , which

resulted in the tourmalin izatio n o f the slate an d the formatio n of

greisen , kao lin ized gran ite , an d dep osition of cassiterite in the slate .

3. The open in g o f the lode fissure .4 . Filling o f the fissure by mean s of hot so lutio n s or pegmatitelike in trusion s .

O n Jurassic Ammo n ite s from East A frica, co lle cte d by

Pro f. J. W. Gre go ry

By L . F . SPATE ,B .Sc .

,F.G.S.

(Con cluded from p .

Gen us SOWERBYCERAS Paron a 85 Bon are lli .Sowerbyceras a ff . tortisa lcato d

’

Orbign y sp . (Pl . 1, Figsf 5a—c. )

1870 . Phyl loceras n . sp . Jurastud . III ,Die Phy l lo c . Dogger Malm ,

”

p . 345 , p l . xvii , fig . 91895 . Ph. subtortisn lcatum (Pomp e ckj Paron a , Nuove o sservaz . s . l . faun a

e l’

eta deg l i strati con Posidon omya alp z'

n a n e i Sette Commun iPal . Ital .

, vo l . i , p . 10 .

1897. Ph. sp . aff. torti sn lratum (d’

Orbign y ) Hochstetter, Die Kl ip p eSt . Ve it be i Wien ,

”

Jahrb . kk . R .A vo l . xlvii , p t . i , p . 142 .

1897 . Sowerbycera s' Neumayri Paron a Bon are ll i, Sur la Faun e Cal lov .

In fer. Savo ie Mem. Acad. Sc . Savoie ser. 4 , vo l . vi , p . 120 .

Dimen sion s — Diameter 15 mm .

Height of the lastwhorl 53 p er cen t of the diameter .

Thickn ess 46

Umbilicus 18

Descrip tion— This sp ecimen i s characterized by a subrectan gular

whorl - section with depressed ven ter,which is peculiar to Fo n tan n e s ’s

352 L. F. Sp ath— Ja rassw Ammon ites from East Afr i ca.

group of Phylloceras tortiéa lcat’

am. The greatest thickn ess o f

the whorls is '

near the umbilical marg in ,but the sides are almo st

paralle l'

an d the ven tral area is even ly con vex, n ot flatten ed . Theratio o f height to thickness is about 7 6, as compared with 4 3 .

in Sowerbyceras tortisa lcatam,accordin g to Pomp eckj,1 an d with

8 7 at most in S . p rotortisulcatam Pomp eckj sp . The umbilicusis comparatively large an d deep ; its walls are roun ded and n ot

abrup t . There are about four con striction s to the whorl,begin n in g

as con sp icuous gro oves with a forward ben d at the umbilicus,

.

but becomin g less distin ct on the lateral area . After ben din g backagain they become o n ce more pron oun ced, passin g across the

p eriphery with a sin us that is con cave forwards .

The suture—lin e c on sists o f very distin ctly diphyllic extern al ,first an d secon d lateral saddles, an d o fmon ophyllic auxiliary saddlesThis typ e o f suture - lime ' is well illustrated in de Lorio l ’s 2 figure o fthat “

of S . tortisa lcatam d Orbign y sp .,

3(which he calls a sp ecies o f

the Renggeri Marls) , an d in that o f S . he lios No etlin g ,4 though here .

the '

saddles,perhap s , are drawn so as to app ear to o p lump . There

are seven auxiliary lobes an d saddles, but the in n er of these are merelyden ticulation s, though presen t already at a diameter“

o f 9 mm .

This n umber agrees with that o f the auxiliary lobes in the threeCallovian sp ecies, S . an teceden s (Pomp e ckj)

5 S .

“1tran sien s

(Pomp eckj) ,6an d S . sabtortisa lcatam (Pomp eckj) .

7 The in tern alp ortion o f the suture - lin e co n sists o f six saddles

,an d it is imp ortan t

to n o te the mo n ophy llic character o f the first lateral saddle (dorsal ) ,which shows the sp ecimen described here to belo n g to the Formenreihe o f Phy lloceras tortisa lcatum Sowerbyceras, an d n ot to

the group o f Ph. a ltramon tan am,as

‘

the backward bend of the co nstrictio n s o f the ven tral area would suggest .

’ The in tern al portio no f the suture - lin e shown in Fig . 5c is n o t drawn from the same parto f the sp ecimen as the extern al half .

Obser-vatio ns .

—Pomp eckj,8 when establishin g the Formen reihe

o fPhylloceras tortis-a lcatam, stated that the developmen tal ten den ciesin this series were as fo llows (a) in crease in the size of the umbilicusfrom the geo logically o lder to the y oun ger forms ; (6) chan ge o fwhorl - sectio n from elliptical to quadran gular, with the greatestthickn ess o f the whorl mo vin g n earer an d n earer to the umbilicus(e ) in crease - in the an gularity o f the con striction s, with a ten den cyto ben d forward a seco n d time on the p eriphery (d) decrease in thecomp lication o f the lobe - lin e . On accoun t o f this last characterPomp eckjcalled the series retro gressive , an d he also men tion ed that

1 Lo c. cit Revision , 1893, p . 54 .

2 1893, text - fig . 1 , p . 5 .

3 d’

Orbign y’

s figure (Ter . Jn rass . , p l . 189 , fig . 3) is p robably in ac‘

curate .

1 Der Jam am Hermon,Stuttgart, 1887 p l . i i , fig . 30 .

5 Lo c. cit Revisio n , 1893, p . 47.

6 Ibid . ; p . 5 1 .

7

8 Loc . e i t Revision,1893, pp . 40—5 .

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Till,

1 S'

. ovale Pompe ckj sp .,

2and Others . .On the o ther han d

,in

the o ldest sp ecimen o f Sowerbyceras figured, the Batho n ian S .

Neumafi t the con striction s are typ ically an gular, an d the thin n esso f that sp ecimen o n ly characterizes it as distin ct .The typ e o f co n strictio n s shown by the sp ecimen here described

is found in the group of Phylloceras ultramon tanum_

Zittel,an d is

well illustrated in e . g . Phylloceras mediterran eum (Neumayr) inFavre

,

3Ph. zign odian um (d’

Orbign y ) in Vacek,4 an d in Ph. Frederici

augusti Pomp eckj,5 but acco rdin g to the latter author in this group

the first lateral Saddle o f the in tern al (dorsal ) suture is diphy llic .

6

Also,though the suture - lin e o f d

’

Orbign y’

s A . zign odian us showsbifid saddles

,n ot. un like tho se o f a Sowerbyceras, the quadrate who rl

section o f the East African sp ecimen an d the absen ce o f the laterallapp et at the an gle o f the con striction s are again st a clo ser com

p ari so n with an y o f the“ fo rms o f the group of Ph. ultramon tanum.

It IS probable that the sp ecimen is most n early related to the o lderforms o fSowerbyceras recorded byNeumayr Paron a,

an dHochstetter .

The former autho r men tio n ed (apart from the sp ecimen from theBathon ian o f Moun t Crusso l , n ear Valen ce

,Ardeche

,referred to

above.) a fragmen t from the Klaus beds o f Buscecs,Tran sy lvan ia ,

7

as the o ldest sp ecimen - which can be referred to d’

Orbign y’

s sp ecies .

Ho chstetter reco rded from the Klaus beds o f St . Veit,n e ar Vien n a,

very small Phylloceras,8 the curious course of the constrictio n s o f

which favoured the assump tio n that they belo n g to Pomp eckj’

s

Formen re ihe o f Ph. tortisulcatum . Paron a reco rded his sp ecimen(doubtfully referred to Ph. subtortisulcatum Pomp eckj to getherwith Lytoceras ade lo ides an d other forms o f the Upp er Baj ocianan d Batho n ian , from the Posidon omya alp in a beds of the SouthernAlp s .

Horizon and Distribution —The group Of PhJlloceras tortisulcatum

(d’

Orbign y ) ran ges from the Batho n ian up to the Tithon ian ,but

1 Op . ci t 19 10 , p . 260, p l . x vi (1 ) , figs . 12—14 .

2 Op . cit. 1893, p . 48 , p l . 1, fig s . 4 an d 5 . This sp eci e s. 1s n ot in cluded in

the g e nus Sowerbyceras by Pai'

on a 85 Bon are l li .3 “

De scr . Fo ss . Ter . Jurass . Mon t. Vo iro n s (Savo ie ) Mé rn . So c: Pal .Suisse ,

vo l i i , 1875 , p . 19 p l . 1, fig . 10 . In this Argovian form the con striction s

are fo i ' to o de ep .

4 Op . cit . , 1886, p l . v ,fig . 14 o n ly , n on p l . iv , figs . 8—10 .

5 Op . cit . , 1893, p l . 1, fig .

b

12—14 .

It may be men tion ed that Que n stedt(Amm. Schwab. Jura, p . 762 , p l . lxxxvi ,an d p . 864 , p l . xciii ) had in cluded in A . torti sulcatus both forin s put byPomp eckj in to the Fo rmem e ihe o f Phy llocera s ultramon tan um also typ ical

So iverbyceras . The Write r is n ot in cl in ed to l ay to o much stre ss on the cou1 se

of the,

con striction s shown to be variable in man y o the r Phyllocera s. On

the o ther han d, Sowerbucei a s i s p ro bably a de scen dan t o f the Baj ocianultramon tanu s group , as Paron a Bon are l l i (lo c. cit. , p . 1 17) sugg e sted .

7 Lo c. cit 1870 p . 345 .

3 Lo c. cit 1897, p . 142 .

9 De Lo rio l (lo c . cit . , 1900, p . 18 ) was doubtfu l about the justification of

the sep aratio n o f Ph. .subtortisulcatum Pomp e ckj from the ty p ical Ph.

'

tortisulcatum d’

Orbign y sp .

L. F. Sp ath— Jurassic Ammon i tes from East Ajr i oa . 355

accordin g to Kilian 1 do es n ot p ersist in to the Bo issieri beds o f thelowest Neo comian . The typ e itself is Callovian an d of widedistribution , bo th in the Alp in e - Mediterran ean region ,

as far as theCaucasus

,but (with related fo rms) also in Wurtemberg .

Locality—No . 10

,from the grey , o therwise un fo ssiliferous

limeston e, beside the break -

pressure tan k , mile on the MombasaPip e—lin e (to gether with Phylloceras cf . disputabi le Zittel) .

Genus PROTETRAGONITES Hyatt .Hyatt 2 created this gen us for Lytoceras quadrisulcatum d’Orbign y

sp .

,a form that is very abun dan t in the Lower Valan gin ian ,

3 thoughsimilar ammo n ites o ccur in the Titho n ian } Vacek 5 traced thegroup o f L. quadrisulcatum back to his Baj o cian L. rasi le , an d

in cluded 6 in the same group L . rubescen s Dumortier sp . an d

L . n . sp . in d .,

7 which forms are assign ed to the genus Megalgtoceras

S. Buckman by its author .

8 Vacek remarked that the Tithon ianLytoceras mun icip ale Opp el sp . was so n ear to L . rasi le that in sp iteof the en ormous chron o lo gical separation on e might almo st bein clin ed to con sider them specifically iden tical . The writer is n o t

convinced that the Tithon ian—Neo comian guadrisulcatus groupProtetragon ites s . str . ) can be traced back even to the .Bathon ian

L . tripartitumRaspail sp . ,an d in fact

,con siders the latter to require

a n ew gen eric n ame sin ce its suture - lin e alo n e clearly distin guishesit from the other Lyto cerata . Owin g , however, to lack o f materialand con sequen t in ability either to prove the independen ce of thisgroup with the n ecessary precisio n ,

o r to trace its relatio n s to

such fo rms as L . rasi le Torn quist n on Vacek ,9 L . tripartitiformeGemme llaro ,

etc . ,the specimen to be described here is provision ally

referred to the genus Protetragon ites .

Protetragon ites cf . trip artitus Raspail sp . (Pl; 1, Figs . 6a - c. )1829 . Amm. trip artitus Raspail , An n . Sci . Obs . (Ly cé , p l . x i, fig . 5 ,

p l . x ii , fig . 7.

1841 . A . quadrisu lcatus d'

Orbign y , Ter. Crét., p . 151

, p l . xlix , fig . 3.

1842 . A . trip artitus (Rasp ail ) , d’

orbign y , Ter . Jurass , p . 496, p l . 197, figs . 1 —4 .

1846 . A . p o lystoma Quen stedt, Cephal op oden , p l . xx , fig . 8 .

1860. A . trip artitus (Raspail ) , Ooster, Cat. Ceph . foss ., p . 66, p l . xvn ,

figs . 1—3.

1 Lethcea geogn ostica,11

,Mesozomum

,vo l . iii , Kre ide

, p t. 1, Un te rkre ide ,fasc . 2, 19 10, p . 171 .

2 In Z itte l’

s Text- book o fPalaeon to logy , edited by C. R . Eastman ,vo l . i , p t . 11 .

1900, p . 569 .

3 Se e e . g . Ki lian , Lethcea geogn ostica,ii , Me sozo icum , vo l . iii, Kre ide , p t . i ,

fasc. 2 , 19 10, p . 174 .

1 Ibid . , p . 171 , an d Sayn“

Amm . Py rit . Marn e s Valan g , S.E . Fran ce

Mem . Soc . Geo l . Fran ce , Pal . , No . 23, 1 901 , p . 2 ) iden tifie s his Valan g in iansp e cimen s with Z itte l ’s Tithon ian ammon ites.

5 Loc. cit. ,1886 , p . 64 .

6 Ibid . , p . 60 .

7 Ibid ., p . 64

, p l . 1, figs . 6,7 .

8 On certain Gen era an d Sp ecie s of Ly toceratidae vo l . lx i ,

1905, p . 15 1 .

9 Loc. cit . ,1898, p . 28 p l . v ,

fig . 8 .

356 L. F.

“Sp ath— Jurassw Ammon i tes fr om East Afr i ca .

1866 A . trip artitus (Raspail ) , Be n ecke , Uh. Trias 11 . Jura i . d . Sud - Alp en

Ge ogn . Pal . Be itr., p . 175 .

189 1 . Lyto ceras trip artitum (Rasp ail ) , Haug , Le s Chain e s subalp . en tre Gape t Dign e Bul l . Serv. Carte Geo l .Fran ce

,vo l iii

, p . 79 .

1897. Ho chstetter Die Klip p e v . St. Ve it,

b . Wien Jb. k.k . R .A vo l . xlvii,

Hft. i , p . 143.

1905 . Simion e scu, Uh. Alt Klaus - Schichte nSud . Karp athen Verh . k .k . B .A. ,

No . 10, p . 212 .

Descrip tion— This fragmen t, con sistin g of two camerae on ly ,

is about 7 mm . in len gth . There is very little differen ce in thedimen sion s o f the two termin al (sep tal ) surfaces, so that the co ilin gmust have ' been extremely slow . The thickn ess o f the who rl isn early equal to the height, which latter is 45 min . The section

,

however,is n ot circular

,but compressed, an d the dorsal furrow is

very shallow,in dicatin g con tact with (but n o t in clusio n o f) the

‘

in n er

whorls . The fragmen t, fortun ately , shows a con striction,with a

forward ben d on the side an d a backward sinus on the periphery .

The suture—lin e co n sists o f very few elemen ts, n amely ,a very lon g

but n arrow e x tern al (ven tral ) lobe , a bifid extern al saddle,about

the size o f the (equally bifid) , lateral lobe , an d slightly larger thanthe (also bifid an d similar) lateral saddle . 1 The seco n d lateral lobeis shorter than the first lateral lobe (which , itself, is shorter than theextern al lobe ) , an d after the very simple an d “

almo st en tire secondlateral saddle there on ly is a very small auxiliary lobe , fo llowed bya broad an d more o r less en tire umbil ical saddle . In describin g thealmost iden tical suture - lin e o f A . trip artitus (Raspail ) d

’

Orbign y2

apparen tly had regarded this auxiliary lobe asmerely an in den tationin the seco n d lateral saddle auxiliary saddle in d

’

Orbign y ) , butthe con tin uation o f the suture - lin e on the dorsal side shows it to bea true third lobe . The deep in tern al lobe is flanked by two lon g an dmon ophy llic saddles . The cro ss

3characteristic o f the group of

Lytoceras fimbriatum (in a wider sen se , n ot on ly Fimbri lytocerasS. Buckman ) is n ot very pron oun ced . The septa are rather distan t(there are o n ly three in the space of 7 mm ) , and they do n ot in terp en etrate .Observations .

-The fragmen t differs in section from the typefigure , an d esp ecially from the compressed examples , such as thatfigured by Quen stedt as A . p o lystoma , by havin g the thickn ess n earlyequal to the height of the whorl . This probably is n ot due o n lyto the small size o f the presen t sp ecimen ,

n o r to the fact that thetyp ical specimen s o f P . trip artitus are gen erally (ellip tically ) compressed . In examp les Of this species from the Bathon ian of the South

1 In fig . 66 the first lateral saddle is drawn just a“

shade to o slen der. On

accoun t of the smal ln e ss of the se sp e cime n s co llodio typ e s could n ot be taken .

2 Lo c . cit . , Ter. Jurase , 1842 , p . 497.

3 Se e Pomp eckj, l o c . cit. , Revision , 1893, text fig . 24 on p . 1 15 .

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358 L. F. Sp ath— Jurassi c Ammon ites from East Afr i ca .

common also in the Batho n ie n In férieur of Fran ce Kilian ,

1

however, men tion s the sp ecies from the Baj o cian again an d statesthat Lory had found it with A . lunula . It seems p o ssible that P .

trip artitus o r a mutation o f that fo rm may go up in to the Callovian ,

but the records o f the higher horizon s are by Older autho rs,

e .g . Quen stedt,

2 Pictet,

3and Studer,1 an d n o men tion is made o f

P . trip artitus in the man y modern des‘cription s of Callovian faun as ,in which , on the o ther han d,

Lytoceras ade loides is almo st un iversallypresen t . At an y rate

,Raspa il

’

s sp ecies is so abun dan t in theBathon ian o f the South o f Fran ce

,that Repeliu 5

even s p eaks o f

a zon e of Lytoceras tripartitumLocality

— No . 550,Mwachi River

,Pip e - lin e Crossin g , about 369 .

(To gether with Phylloceras cf. Kun thi Neumayr and Hecticocerassp . juv . )

Gen us HECTICOCERAS Bon are lli .The specimen described here is an undoubted Opp e lid,

but its

referen ce to the genus Hecticoceras is somewhat doubtful . Its

asso ciation with Ammo n ites that are comparable with Bathon iansp ecies suggests affin ity with those Bathon ian Opp e lids that havebeen put in to Hecticoceras by e . g . Haug , Popovici - Hatzeg , an d

Paron a . These forms,o n the o n e hand

, seem to be allied to some o fthe n ormal evo lute Gflcotraustes of the Parkin son i an d fuscazon es, but n o t to the early (Ecotraustes, such as that figured byVacek ,6 which has a differen t suture - lin e . On the o ther hand,

theyprobably develop in to such more o r less invo lute forms Of

' themacrocephalus beds as Opp e lia p leurocg/ma Paron a Bon arel li ,

7

or as Opp elia subdisca d'

Orbign y sp .

8 These forms have been co n

fused with the earlier an d similar Opp e liaof thefusca typ e , and withOrgeerites, group s that are invo lute an d already have a highlysp ecialized suture—lin e in the Bathon ian . To separate , however,the developmen t here in dicated from the later an d similar

1 Mo n tagn e de Lure , Paris (Masso n ) , 1889 , p . 79 .

2 A . p o lystoma Quen stedt is re corded from a black limeston e of macrocep halus age from Barreme .

3 This autho r (’l ’raité de Pa l . , vo l . ii , 1854 , p . 698 ) stated that A . trip artitus

was characte ristic o f the Cal lovian in Fran ce,an d was foun d in German v

together with A . Murohison ce .

1 In Geo logi e d. Schweiz,1853,

vo l i i ,‘

p . 45,A . trip artite s is recorded as

o ccurrin g , with Phy lloceras zign odian um an d Macrocep hal ites ,in

‘

the Cal lovian ,

but on p . 52 it is asso ciated with S . tortisulcatum,Ph. tatricum,

an d also

A . p licati l is , an d put‘

in to the Oxfo rdian .

5 Jurass . Chain e Nerthe e t l’

Eto ile Bul l . Soc . Geo l . Fran ce , ser. III ,

vo l . xxvi , 1898 , p . 520 . Ph. medi lerran eum an d Op p e lia here o ccur withP . tr ip artitus .

6.Lo c . cit.

, 1886 , p l . ix ,fig . 13. S. Buckman ( Certain Jurassic Specie s o f

Amm . an d Brach .

”

vo l . l xvi , 19 10, p . 96) is in clin ed to put thisas low as the discites zon e .

7 Loc. cit . , 1897, p . 129 , p l . iii , fig . 1 .

8 Loc . cit Ter. Jurass, p . 42 1 , p l . 146, an d Favre , Con trib. a l

’

Etude desOpp e lia Mem. So c . Pal . Suisse ,

vo l . xxxviii,19 12

, p . 31 ,

L. F. Sp ath—Jurass ic Ammon i tes from East Africa . 359

Lunuloceras 1 would be op en to o bj ection s from etymo logicalreason s, for A . hecticus itself would then be a Lun uloceras . In an ycase the defin ite relation s of the man y forms referred to the genusHecticoceras remain y et to be worked out, also the con n exio n withOpp e lin ce below an d the Ochetoceras—Trimargin ites faun a above .

Hecticoceras sp . juv . (Pl . 1 , Fig . 7a—o . )Compare

1905 . Hecticoceras Han gi , Pop o,vici - Hatzeg ,

Le s Ceph . Jurass. M.

Strun ga Mem . , So e . Geo l . Fran ce ,Pal . , No . 35 , p . 18 , p l . iv ,

fig . 3, p l . v, fig s . 2 10 .

Dimen sion s —D iameter 8 3mm .

Height o f the lastwhorl 40 p er cen t o f the diameter .

Thickn essUmbilicus 30

Descrip tion— This specimen represen ts o n ly the in n er whorls o f

a larger ammon ite sin ce it is septate throughout . The p eripheryshows a keel on ly o n the last two - thirds of the outer whorl , and theearlier p ortio n of the shell is p erfectly smo o th , with flat sides an d a

roun ded ven ter . The op en umbilicus has steep but roun ded walls .

The orn amen t which is shown n ear the en d o f the shell (in the fo rmo f about six co stae) is distin ct n ear the p eriphery on ly an d on lyo n e or two o f these obscure fo lds seem to be very in distin ctlycon tinued, with a lateral forward ben d,

on the sides, though they don ot reach the umbilical border . There is an in dication n ear the en do f the sp ecimen o f a differen tiation o f the p eriphery in to lateralzon es (on each side o f the keel ) marked o ff from the sides by an edge ,whereas on the previous p ortion o f the last whorl the ven tral areais roun ded and gradually passes

'

in to the sides .

The suture—l in e co n sists o f a deep ly forked,trifid prin cipal lobe ,

much deep er than the extern al and secon d lateral lobes , o f irregularlybifid extern al first an d secon d lateral saddles and o f three auxiliarylobes, slightly raised towards the umbilicus .

Observation s .

—The suture - lin e o f this specimen is very similarto that o f a y oun g Lunulooeras, an d agrees in all essen tials with thato f Harp oceras lunula (Zieten ) given by No etlin g ,2 or with thesuture - lin es of a number o f sp ecimen s

'

o f this almost un iversalsp ecies -

group from man y differen t lo calities . On the o ther han d,

the suture - lin e o f y oun g Opp e lids from the zigzag hemera of“

Powerstock Station

,Do rset

,is also very similar to that of the sp ecimen

here described,as is that given for Op pe lia subradiata (Sowerby )

var A . by Favre .3 With a very immature sp ecimen it is a mattero f op in ion whether it should be con sidered as allied to the Bathon ian

1 Tsytovitch Le g en re Hecticoceras Mem . So c . Pal . Suisse ,vo l . xxxvi i ,

19 1 1 ) has again drawn atten tion to the difficulty of sep aratin g Hecticoceras

an d Lun uloceras on pure ly mo rpho l ogical groun ds.

2 Der Jura am Hermon,1887 , p . 18, text - fig . 3.

3 Lo c. cit . , 19 12 , fig . 1 on p . 13.

360 L. F. Spath— Jurassi c Ammon i tes from East Afr ica .

Hecticoceras 1 rather than to o ther con temp oran eous Opp e lids .

It should be p o in ted out, however, that the East African sp ecimenmight equally well represen t f the in n er whorls of such CallovianLunuloceras as tho se figured by ,

Quenstedt,

2 Waagen ,-3 Till

,

‘

Tsytovitch, etc . , or even o f such Oxfo rdian an d Argovian forms as

tho se figured by de Lorio l 5 an d No etlin g .

6 As has been p o in tedout before , its affin ity with the Bathon ian fo rms o f the typ e o fOpp e lia bisculp ta Opp el sp .

= A . Hen rici Kudern atsch n on

d’

Orbign y7 is suggested on ly by the asso ciated ammon ites .

Hecticoceras Haug i , Pop ovici - Hatzeg , has a n arrower umbilicus inthe adult

,an d the whorl - section

,then

,also differs con siderably?

but the youn g probably comes very n ear to the sp ecimen hereexamin ed . On the o ther hand,

the suture - lin e appears to be moreComp lex in the Rouman ian sp ecimen s .

Horizon .— Hecticoceras, comparable to the East African specimen ,

o ccur in the Bathon ian as well as the Callovian .

Locality .

—No 550,Mwachi River

,Pipe - lin e Crossin g . Foun d

together with Protetragon ites cf . trip artitus Raspail sp . and withPhylloceras cf . Kun thi Neumayr .

CONCLUSIONS .

The faun a described in the presen t paper con sists,then , of the

fo llowin g seven Ammon itesPhyl loceras aff . Kudernatschi Hauer .

sp . in d .

cf . Kun thi Neumayr

cf . disp utabi le Zittel .fSowerbyceras sp . aff . tortisulcato d

’Orbign y sp .

Protetragon ites cf . trip artitus Raspail sp .

Hecticoceras sp . juv .

It is a matter for regret that more defin ite iden tification s could n otbe given ,

but n ot o n e of the specimen s represen t-s an adult shell ,and three o f them are fragmen tary . It is o n e of the latter (Protetragon ites cf . trip artitus) that has been main ly relied on

,in

determin in g the faun a as'

probably of Batho n ian age ; but thisspecies already o ccurs in the Parkin son i beds of the uppermost

1 As rep re sen ted by e .g . Op p el ia retrocostata Gro ssouvre Etude s sur

1Etage Bathon ie n”

Bul l . So c . Geo l . Fran ce , ser. III,vo l . XVI, 1888 , p . 374 ,

p l . iii , fig s . 8, 9 ) an d the Co rn brash sp ecie s Harp oceras (Ludwigia )

subpun ctatam (Schlip p e , Faun a Bath . Oberrhe in . Tiefi . Ahh . Ge o l . Sp ec .

K . Els .- Lo th-r. vo l . iv ,

1888 , No . 4 , p . 196, p l . v ,

fig . Haug

p . 82 ) con siders them iden tical .

Amm. Schwdb. Jura , 1887 , p l . lx xxn , e . .g figs . 23 an d 32.

3 xiii .4 Lo c . cit. , 19 10, e . g . , p l . xviii (iii ) .5 Lo c . cit. ,

1898, e . g . H. Bon are l li i , de Lorio l , p l . iii , figs. 19—21 , an d 1900 ,

p l . iii , p . 14 .

6 Lo c. cit. , e . g . Harp oceras Guthet'

,Noetlin g , p . 20 , pl . 11 , figs . 6—8a,

7 Lo c. cit.,1852, p l . _

ii,figs . 9—13.

3 LOCi cit.,1905, te xt - fig . 9 on p . 19

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362 L. F. Sp a th— Jurassi c Ammon i tesfr om East Afr ica .

in determin able Cephalop od remain s so far have been reco rded fromits ro cks . It IS in terestin g to n o te that Six out o f seven specimen sdescribed 1n the presen t pap er belon g to the lo n g - l ived an d stablegen era Pkg/ lloceras and Lytoceras givin g the faun a a typ icallyMediterran ean asp ect . The in flux of this Mediterran ean faun a musthave o ccurred alon g the geosyn clin al exten sion o f the Tethys,which has been called the Chan n el o f Mo zambique This ge osyn clin al , before the Batho n ian tran sgression ,

apparen tly had n ot

attain ed the edge o f the presen t African con tin en t . A Son n in ia

an d a Parkin so n ia , but n o Phy lloceras or Lytoceras have been foundin the Bajocian o f Madagascar, but n o pre

- Bathon ian ammon iteso ccur on the African con tin en t west o f this geo syn clin al .Hecticoceras is foun d in North -W

'est Euro p e an d in the borealCallovian as well as inAlpin e - Mediterran ean dep o sits . On the o therhan d

,Phylloceras and Lytoceras have been foun d in Alaska,

thoughthere '

also they are claimed to be co n fin ed to a geosyn clin alexten sion of the Mid - Pacific (which latter en abled the exchan ge o fthe '

Spiti an d An din e faun as) . Professor Haug’

e co n cep tion o f

Phylloceras an d Lytoceras as sten othermal gen era, frequen t on lyin the deep est parts o f the geosyn clin al areas , do es n o t explain al l

the facts of their distribution . In a previous pap er the writerfavoured the view that l ike o ther thin - shelled o rgan isms

,but un like

man y o ther Ammo n ites an d Nautilo ids,Phylloceras an d Lytoceras

may have been p elagic swimmers,an d thus in their distribution

show a certain dep en den ce o n the curren ts o f the Jurassic seas .

EXPLANATION OF PLATE V.

FIG . 1 .- Phy lloceras a ff. Kudernatschi (Hauer) . Mombasa Pip e

- lin e ,at

mi le 152

. ( x about 1 1a,lateral asp ect ; l

'

h,

section al outl in e ;

l o , suture - lin e x about

FIG . 2 .— Phy l loceras sp . in d. We st o f Mwachi River, about 1

01

. Nat. size .

2a,lateral view ; 26, outl in e - section ; 2c, p ortion of suture - l in e

x about

FIG . 3.

—Phy lloceras cf. Kum‘

hi Neumay r. Mwachi Rive 1 , Pip e - l in e Cro ssin g .

Nat . Si ze . 3a, lateral asp ect ; 3b, p eripheral view 3c, suture - l in e

( x about

FIG . 4 .

— Phylloceras cf. disputabi le Zitte l . Mombasa Pip e lin e , mile in } .

4a , lateral asp ect x about opp o site side ,showin g con striction s ,

with re stored outl in e of comp le te she ll , n at. Size ; 40 , outlin e section of

whorl , magn ified x 2 ; 4d, suture l in e (p ortion ) x about 6 .

FIG. 5 .

— So -werbyceras aff. tortisu lcato d’

Orbign y sp . Same lo cality as last .

5a, latera l asp e ct ( x about 1 l ) 5b, outlin e section ,

magn ified x 2 .

5c, suture - lin e, comp osite an d n ot drawn fl om o n e sep tal edge .

FI'

G . 6 .— Protetrago n ites cf. trip artitus (Rasp ail ) . Mwachi River, Pip e - l in e

Cro ssin g ,about 20

9. 6a ,

- lateral asp e ct, magn ified x 2 66, section x 2 )6c, s uture - l in e , e xte rn al an d in tern al ( x about

FIG . 7 .—Hecticoceras sp . juv . Same l o cal ity as last . 7a

,lateral asp ect x 2 )

7b, p e riphe ral View ( x 7c, suture - l in e ( x abo ut

H A . Baker— Loose Aren aceous Sedimen ts .

On the In ve stigatio n o f the Me chan ical Co n stitutio n

o f Lo o se Are n ace o us Se dim e n ts by the m e tho d o f

Elutriatio n , w ith sp e cial re fe re n ce to the Than e t

Beds o f the Southe rn Side o f the Lo n do n Basin .

By HERBERT ARTHUR BAKER,M.Sc.

,F.G.S.

(Co ntin ued from p .

GRAPHICAL EXPRESSION OF MECHANICAL ANALYSES .

IN givin g graphical expression to the data obtain ed by mechan icalan alyses o f sedimen ts , the use . of curves was foun d to be very

satisfactory . After some con sideration the method fin ally adop tedwas to mark off alon g a ho rizo n tal abscissa a scale o f percen tageweights, from 0 - to 100, an d upwards, alon g a vertical ordin ate ,a scale of grade - size limits from 0 to

'

2 mm . an d bey on d . In caseswhere the ran ge of the diameters o f the grain s in a sample is verygreat it would be n ecessary to emp loy a method of reducin g therepresen tative len gths, and this has sometimes been don e by markin goff len gths p rop ortion al to the logarithms of the diameters ; butin the case Of the aren aceous sedimen ts dealt with by the writer,the n ecessity for this did n o t arise

,an d in the curves illustratin g

this paper,the ordin ate len gths shown are directly prop ortio n al to

the diameters rep resen ted . The len gth alon g an abscissa , intercepted between the first o rdin ate an d the curve , represen ts thetotal percen tage weight o f the samp le which , up to the limit of Sizesp ecified, has been washed off

,an d the remain in g len gth sign ifies

the percen tage - weight y et remain in g to be dealt with . A ten den cytowards verticality on the part o f the curve den o tes relative absen ceor paucity of material of the Sizes specified,

an d,correspon din gly ,

a tenden cy towards horizon tality sign ifies a prep on deran ce o f

material o f the size Specified . Hen ce,a fin e -

grain ed sedimen twill give a curve occupy in g the lower part of the diagram ,

an d

with in creasin g coarsen ess of sedimen t the curve climbs successivelyhigher an d higher . (Se e Figs . 2

,3,an d

TREATMENT OF DATA YIELDED BY MECHANICAL ANALYSES .

(1 ) Fai lure of the Purdy Fin en ess Factor

A method whereby the mechanical con stitution of a sedimen tcan be expressed by mean s of a represen tative number has beenmuch sought after, but up to the p resen t n o really satisfactoryresult has been achieved . Such a n umber

,could it be obtain ed,

would un doubtedly be o f great utility . It could be p lo tted up on

map s , and ideas co n n ectin g the mechan ical con stitution o f a sedimen twith its geographical distribution could be gain ed . The n eed forsuch a n umber in con n exion “ with the eco n omic asp ect o f themechani cal comp o sition o f san ds an d clays is much felt . In

America an attemp t has been made to obtain a fin en ess factorwhich Shall be proportion al to the total surface - area of the sample .

364 H. A . Balcer— Loose Aren a ceous Sedimen ts.

The assump tion is made that the surface - areas of two powders,

derived from a un it vo lume, are in inverse ratio to the averagediameter of their grain s, an d the reciprocal o f the average diameteris taken

,

as the factor . The assumption is n ow kn own to beerron eous, but as the factor affords a

_

con ven ien t approximatio n itis o ften used . This factor was proposed by Jackson ,

an d amendedby Purdy , and go es un der the n ame of the Purdy fin en essfactor ”

. It was first prop oun ded to meet the requiremen ts of theceramic industry , but it has been -

admitted that sin ce the differen cebetween the true surface - factor and that calculated from the averagediameter in creases as the diameter decreases

,more co n fiden ce may

be p laced in the Purdy factor as calculated fo r sedimen ts coarserthan the fin e material used 'in the ceramic in dustry . The methodof obtain in g the Purdy fin en ess factor will be clear from thefo llowin g :Supp ose the samp le to have been separated by elutriation in to

four grades, thus

Diamete rs Percen tage - we ightGradeIan g In g from pre se n t.

a to bmm .

b to c

c to d

Then the Purdy fin en ess factor to tal surface facto r

a b 100 b c 100 0 + d 100 100

The to tal surface—factor is obtain ed by multiply in g the surfacefacto r o f each grade by the p ercen tage weight o f that grade , andfin din g the sum o f the products thus obtain ed .

Before pro ceedin g to test the utility o f the Purdy fin en ess factorin relation to aren aceous sedimen ts

,it is legitimate first to make

the criticism that the true average diameter o f the grain s in an yseparated grade is likely to be seriously differen t from the half- sum

of the limitin g Sizes .

Bearin g in min d that the Purdy fin en ess factor should Showlarger numbers fo r fin er sedimen ts

,the above formula was app lied

to the results of a large number o f mechan ical an alyses carried out

on aren aceous sedimen ts by the writer . The result was to Show thecomp lete failure o f this factor to serve an y useful purpo se as a mean sof comparin g aren aceous Sediments from the po in t of View offin eness

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H. A . Baker— Loose Aren aceous Sedimen ts .

comparison for the fin en ess or coarsen ess of grain of aren aceoussedimen ts .

From the mathematical p o in t o f view the question presen ts greatdifficulties . It do es n ot app ear to be p ossible to app ly any Simp lemathematical p ro cess to the data afforded by elutriatio n ,

whichdo es n ot deprive them o f their un iquen ess . Moreover

,the app lica

FIG . 2 .— Elutriation curve s o f sedimen ts (reduced) to show mean in g o f

Equivale n t Gradetion o i the ordin ary pro cesses of mathematics to the elutriationcurve o f a sedimen t would on ly give some result o r results basedupo n a series o f mathematical curves agreein g more or lessapp roximately with p ortion s o f the actual curve . The latter bein gavailable , the presen t writer '

is o f o p in ion that it is better to obtainsome result or results from actual treatmen t o f the graph itself .

H. A . Baker— Loose A r en aceous Sedimen ts . 367

In the search for a characteristic n umber to represen t themechan ical con stitutien of a sedimen t, the actual average diameterof the grain s in a sample, besides bein g exceedin gly difficult , if n otimp o ssible to obtain ,

is useless,Sin ce it gives a result quite out

of keep in g with the sizes o f the grain s in the bulk of the sample .This arises from the fact that the clay grade in the sample, howeverin sign ifican t its p ercen tage - weight may be , con tain s such an

en ormous amoun t o f tin y particles that “ the average diameter isreduced to a figure of an order quite differen t from that sought .Con sequen tly a method is’

required which affords a result in fluencedby the percen tage - weights o f the vari ous grades presen t .

(2) The‘Equivalen t Grade of a Sedimen t.

The plo ttin g o f the elutriation - curve o f a sedimen t from the datay ielded by the mechan ical an alysis of it, affo rds a means o f obtain in ggraphically ,

the value o f the defin ite in tegral o f diameter o f particleswith respect to percen tage - weight . The value o f this in tegral isrep resen ted by the area un der the curve en closed between the firstan d last ordin ates an d the first abscissa o r base - lin e of the diagram .

It may readily be determin ed,with co n siderable accuracy , by the

use o f the plan imeter . The result is small or large , accordin g as

the sedimen t.

un der con sideratio n is fin e o r coarse , sin ce the coarserthe sedimen t the higher its curve climbs an d the greater the areaen clo sed ben eath it . If we supp ose the case o f an ideal sedimen t inwhich the gradin g is perfect (i . e . the sedimen t con sists en tirely of

grain s o f some o n e sp ecified diameter) , the elutriation - curve wouldbe a horizon tal straight lin e (an abscissa) , parallel to the firstabscissa an d passi n g through the p o in t o n the first ordin aterepresen tin g the sp ecified diameter . Let us supp ose , for argumen t ,that all the grain s in this ideal sedimen t are of diameter 02 mm .

Then the area un der the curve is a rectan gle whose area is a producto f the len gth represen tin g 02 mm . an d that represen tin g 100 p ercen t weight . .The figure sought as the represen tative average o fthe diameters of the particles (takin g in to accoun t percen tageweights o f grades) is obtain ed by dividin g the area un der the curveby the len gth o f the base lin e represen tin g 100 p er cen t weight ,an d in terpretin g the len gth so obtain ed i n terms of the scale oflen gths employ ed to represen t diameters . Now

,perfectly graded

sedimen ts of this kin d do n ot app ear “

to o ccur in n ature,but there Is

n o reason why we should n o t exten d the argumen t, by an alogy ,to

app ly to actual sedimen ts . Con sider an imp erfectly graded n aturalsedimen t . It gives a certain kn own value for the in tegral of diameterof particles with respect to percen tage—weight . Suppose it werep o ssible to substitute for this sedimen t a p erfectly graded materialgivin g an equivalen t value for the area un der the curve . What wouldbe the diameter o f the particles in this ideal sedimen t '

l The an sweris supplied by findin g the mean ordin ate o f the area under the curve

,

If . A . Baker— Loose Arenaceous Sedimen ts .

which is do n e by fin din g the area un der the curve by mean s of theplan imeter an d dividin g the result by the len gth represen tin g100 p e r cen t weight . The len gth so obtain ed is then in terpreted interms of the scale

_

o f len gths employ ed'

to represen t diameters .

The value o f this mean ordin ate may then very well be taken as therepresen tative diameter, for comparative purpo ses, of the particlesin the sedimen t . The figure o btain ed may be termed theEquivalen t Grade for the particular sedimen t .Fin e sedimen ts will give alow .figure for the Equivalen t Grade

an d the figure will in crease with in creasin g coarsen ess of sedimen t .On app ly in g this method to the two sedimen ts con sidered above ,when referrin g to the Purdy factor, we fin d that samp le A (thecoarser sedimen t) gives an Equivalen t Grade o f 120 mm .

,whereas

the fin er samp le B gives 087 mm . As the result of app ly in g themethod to the data obtain ed by carry in g out a very large numberof mechan ical an aly ses of aren aceous sedimen ts

,the writer n ow

con cludes that we have , in this Equivalen t Grade ” ,a valuable

mean s o f comparin g sedimen ts from the p o in t o f view o f theircoarsen ess o r fin en ess of grain ,

an d o n e superior to an y methodat p resen t in vogue .

(3) The Grading Factor of a Sedimen t.

It can n o t be said,however, that the Equivalen t Grade supp lies,

a figure which is un ique for each and every sedimen t . The elutriationcurve o f a sedimen t is un ique— each an d every sedimen t gives itsown particular curve— an d o n ly two mechan ically iden tical sedimen ts x

would y ield iden tical curves . It is po ssible,however

,for two differen t

curves to y ield the same Equivalen t Grade figure . Hen ce it isn ecessary fo r a further factor to be obtain ed

,based upon the

resp ective prop ortion alities o f the grades presen t in the sedimen t,so that this secon d figure , taken in con jun ction with the Equivalen t“Grade, affords a pair of n umbers which together give completeun iquen ess to an y sedimen t . The writer has devised a mean swhereby a secon d figure— a Gradin g Factor —can be obtain ed,

so that if two sedimen ts give the same Equivalen t Grade they differin their Gradin g Factor, and vice versa . In ciden tally , theEquivalen t Grade an d the Gradin g Factor o f a sedimen t are figureswhich should prove of the utmo st utility in con n exion with theecon omic asp ect o f the question of the mechan ical con stitution of

sedimen ts, an d,further

,there i s every reason to suppose that as

our kn owledge of' the con dition s govern in g the tran sport, sortin g ,an d deposition o f sedimen ts pro gresses, they will , in addition ,

prove o f con siderable value to the geo logist .The Gradin g Factor of a sedimen t is foun d as fo llows : Curve 0

in Fig . 2 represen ts'the elutriation - curve of a sedimen t (Lower

Than et Beds, Charlton Pit) , which gave the fo llowin g mechan ical

an alysis

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H. A . Baker— Loose A r en aceous Sedimen ts .

SILT . SAND .

< ~Ol r nn L - 1 rn nL

26 - 20 70 - 90

The Equivalen t Grade o f this sedimen t is iden tical with that o fthe first

,

“

viz .

‘

059 mm .

,but the two curves are n o t iden tical . It can

be seen at a glan ce that the first sedimen t shows greater variationthan the second,

and hen ce the latter y ields a higher Gradin g Facto r,the value in this case comin g out at

“

693. - We see,then ,that the

Equivalen t Grade of a sedimen t to gether with its Gradin g Factorafford a pair of values unique for an y sedimen t .It should be remarked that in selectin g sedimen ts to serve asillustratio n s of the utility o f these two factors, the writer has

deliberately cho sen examp les in which the differen ces in mechan icalcon stitution are by n o mean s great . In gen eral, aren aceous sedimen tsshow very much greater differen ces in mechan ical compo sition thanare to be observed in the examp les selected . If

,then comparatively

in sign ifican t differen ces can be in dicated by themethods o f treatmen there outlin ed,

how much more apparen t become the greaterdifferen ces very gen erally foun d .

When the data y ielded by mechan ical an alyses of sedimen ts haveaccumulated sufficien tly ,

it should be a simple matter to draw upa scheme of classificatio n

,accordin g to mechan ical con stitutio n ,

for the lo ose detrital sedimen ts, based up on determin ed values o f

Equivalen t Grades an d Gradin g Factors . The determin atio n o f

the values of these facto rs in the case o f those sedimen ts which areused in the industries can hardly fail to be of great utility .

_The

imp ortan ce of mechan ical con stitutio n in the case of glass sands

and in the case of the refractory san ds used fo r furn ace an d foun drypurpo ses has already been clearly demon strated by Pro fessorBo swell . But from the purely geo logical p o in t of view there is everyreason to believe that from the detailed study of the mechan icalco n stitution o f the lo o se detrital sedimen ts of the geo lo gical co lumn ,

much light will be thrown up on man y obscure question s, especiallyin referen ce to con dition s o f deposition of sedimen ts . Whenp alee on to logical eviden ce fails, the stratigrapher is thrown backup on the litho logy o f the dep osits, an d in the case of a lo o se ,aren aceous sedimen t the litho lo gical eviden ce is very stro n gly an d

help fully augmen ted if the elutriation - curve be available .

(To be con tin ued . )

ECHINOID on CRINOID’

2

UEBER EINIGE PALAEOZOISCHE SEEIGELSTACHELN,(TIMOROCIDARIS

GEN . Nov. UND BOLB OP ORITE S PANDER ) . By JOHANNES

WANNER . Versl . Natuurk . Afde e l . Akad . Weten sch . Amsterdam,

xxviii, pp . 797—813, pl . 1920 .

ROFESSOR WANNER has foun d in the Permian o f Timor

some echin oderm remain s which he believes to be radicleso f an echin o id, an d therefo re n ames Timorocidaris . In shap e on eo f these obj ects is like a mushro om,

with rounded top an d shortstalk . The alleged upper outer face is n ormally pustulate, butsometimes smoo th . The circular outlin e is sometimes modifiedby trun catio n s, as though these suppo sed radicles had been crushedclo se together o n the

'

test,as are the radicles of Co lobocen trotn s .

The large maj ority out o f o f these bodies have the en do f the stalk bevelled off by three facets, which meet roun d a smallcen tral ho llow . The remarkable feature is that these three surfacesare fashion ed as articular facets with a pron oun ced crin o idcharacter.

”

Each facet shows the fulcral ridge, separatin g an outercrescen tic ligamen t—face from the two in n er muscle - p lates , which arediv ided by a median gro ove o r n otch . At the middle of theligamen t - face, adjo in in g the fulcral ridge and o pp o site the n o tch ,is a depression ,

which may in dicate a more pron oun ced ligamen tscar (as Dr . Wan n er in terprets it) o r a can al fo r a n erve . Someof the remain in g sp ecimen s have merely a ho llow at the end of

the stalk, and Dr . Wan n er believes that this ho llow represen tson e of the facets . He claims to have - material p rovin g a passagefrom o n e typ e of structure to the o ther

,but his

l

figures are n ot

convin cin g . Some of the sp ecimen s have an orn amen t resemblin gthat of Cidaris scrobicn lata an d on e o r two o ther radicles fromthe Alpin e Trias .

It is p ossible that there are some true echin o id radio les in thismaterial, but I am at a loss to un derstan d how the maj ority with thethree articular facets can be in terpreted thus . Settin g aside thefact that n o such structure has ever been seen in the Echin o idea,

is it n ot obvious that such facets could n ot have been used for theattachmen t o f on e rigid body to a sin gle rigid surface o f whatevershap e Each of these facets must have been attached to a separate ,movable, skeletal elemen t of similar section

,i . s . with a roun ded

outer back an d gro oved in n er surface . That which was'

fix ed as the

stalk,that which wasmovable

,was the group o f structures attached

to the facets . Those structures must have diverged from on e

an o ther at the outset .Dr . Wan n er makes a number of hyp o theses, each of which hetests con scien tiously and fin ds unworkable he also exerts himself

Revi ei us— Echi n o i d or Cr i n o id

to smo o th away certain o ther obj ectio n s to regardin g these obj ectsas radicles; i n ter alia the to tal absen ce from his co llection s o f an ycoron al p lates to bear them . It n ever o ccurs to him to make thehyp o thesis that these obj ects are crin o ids after all . Let us se e

how that works out . Each,we may supp o se, has n ormally three

radials , laterally fused in to a sho rt stalk,an d sprin gin g from a so lid

rounded mass in to the comp o sition of which the basals (an d in frabasals , if an y ) presumably en ter . Each radial facet supp orted, ,on

this hyp o thesis, the first brachial of an arm. As to the n ature o f thosearms we have n o eviden ce o ther than that afforded by the facet ,from which we gather that they were in depen den tly movable an dmoderately massive . They must have in cluded the viscera ,

sin cethere is n o t sufficien t space between the radials

,and therefore were

p robably j o in ed laterally by a fin ely p lated membran e .On this hyp o thesis the hemisphere from which the radial stalk

sprin gs was a sort of an chor restin g on the sea - flo or, p erhap s sometimes embedded ih san d or sometimes in serted in a crevice whichchecked its free growth . Some o f the sp ecimen s may have beendragged alo n g the bo ttom an d so lost their pustules . Others mayhave been partly weathered an d have had their facets eaten away .

Individuals fixed in awkward p osition s may have develop ed o n e

o r two facets at the exp en se o f the o thers . All such aberran t casesdo n ot amoun t to 12 p er cen t: .The crin o id hypo thesis, then ,

seems

o pen to fewer obj ection s than the echin o id . Just as Dr . Wan n er’

s

Timorecki nus proved to be a crin o id allied to the Poteriocrin idee ,so his Timorocidaris will probably turn out to be a crin o id withstem reduced to a massive an chor

,as in Agassizocrin n s an d with

arms reduced to three , as in Tribrackiocrin as . It may be gen eticallyco n n ected with on e or o ther o f those late Carbon iferous gen era ,

but that 1s n ot a n ecessary con clusion .

Professor Wan n er argues from his supp o sed radicles with theirabn o rmal facets to Bolbop orites, which likewise he in terprets as an

echin o id radio le with a p eculiar facet . If,however, Timor'

ocidaris

be a crin o id,this an alogy loses its force . In n o o ther resp ects do es

Dr . Wan n er throw fresh light on Bo lbop orites . Had he taken thetrouble to make thin sectio n s through his sp ecimen s and to studytheir stereom with the ml cro scop e , he might have substituted someuseful fact for a deal o f in gen ious but, I fear, useless fan cy .

F . A . BATHER

THE PALazo zo rc TILL -ITES o r NORTHERN , NORWAY . Bidrag tilFinmarken s Geo lo gi , av OLAr HOLTEDAHL . Norges Geo

lo giske Undersoke lse , Nr . 84 . Kristian ia, 1918 .

N 1890 Dr . Hi Reusch an n oun ced his discovery in theVaran gerfjord district,E . Finmarken ,

o f rocks o f glacial originbelon gin g to a much o lder p eriod than the Ice Age ’

. He referredthem to the Palaeo zo ic an d,

rely in g up on the p etrographicalsimilarity o f the beds asso ciated with the tillites to the Sparagmite

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374 Revi ews - fi The A rbou i n Copp er Min es a t Cardross .

west,with its down throw side to the north , an d these movemen ts are

correlated with the Middle Ordovician disturban ces o f Scotlan d an d

No rth America . The Upp er Series derived its material from thehighland s outh o f~the fault, which was a pre - Cambrian area ,

in partbelon ging to the land barrier, with remn an ts o f the lower do lomitebearin g series .

The tillites o ccur at two horizon s . The lower is a local depositrestin g up on a gro oved p avemen t, and con tain in g ice - scratchedboulders o f gn eiss, gran ite, and sandsto n e . Asso ciated con

glomerates co n tain p ebbles o fi

chert,an d do lomite with o o litic an d

stromato litic structures . The upp er tillite con tain s ice - scratchedboulders

,but is of a

'

differen t character ; it is o f very even thickn ess ,exten ds over a wide area

,an d passes downwards in to the even

grain ed un gro oved sandsto n es ben eath , thus in dicatin g a glacialdep osit laid down under water from floatin g ice . The lower tilli te,0 11 the o ther han d

,is of a co n tin en tal typ e .

Dr . Ho ltedahl refers the tillites '

to some p eriod between the LowerOrdovician and Upper Silurian ,

an d lays stress up on the fact thatthey do n ot n ecessarily in dicate a climate as co ld as that o f n orthernNorway at the presen t day . It is to be hop ed that fossils will so onbe foun d in these beds

,and their exact age established bey on d doubt .

Their n on - discovery up to the presen t is n ot in compatible with theage p o stulated, for con siderable thickn esses of the Durn essLimesto n eare barren ,

an d limesto n es o f undoubted Cambro - Ordovician age

in No rth America o f the same p etrographical character have failedto y ield fo ssils . Dr . Ho ltedahl

’

s researches in dicate that the tilliteswere formed before the Caledon ian deformatio n attain ed its

maximum, which was in Lower and Middle Silurian times, an d thatn o gen eral climatic chan ge is to be in ferred from them .

L . HAWKEs

THE ARBOUIN COPPER JMINES AT CARDROSS . By L . C. BALL .

Queen slan d Geo logical Survey ,Publication No . 261 . pp . 69 .

Brisban e,19 18 .

THE Arbouin Copp er- min es are situated in North Queen slan d,about 20 miles west o fMun gan a, the termmus o f the Chillago e

Railway . Geo logically the Cardross district is comp osed en tirely of

pre—Silurian schists an d gn eisses, and on ly to the east, about

Mun gan a ,are these overlaid by Silurian shales and limeston es .

The schists an d gn eisses have been invaded by an o ld series of basicdykes, n ow in the co n dition either of amphibo lites or diorites

,an d

later, probably at the time o f the in trusion o f the Permian gran itesby p egmatites and elvan dykes , accompan ied by metalliferouslodes .

There are several belts o f min eralizatio n ,an d the tren d o f these

and o f the in dividual lodes is about n orth—east an d south - west .The elvan s

,though havin g a tren d gen erally at right an gles to the

lode direction ,are eviden tly closely con n ected with the ore bodies,

0

Revi ews— The Ken t Coa lfield. 375

sin ce in proximity to a dyke the lode is always richer, while in theabsen ce o f dykes the lodes are o ften barren . This relation ship ,

coup led“with the fact that the dykes Often carry sulphides in workable

amoun t, leads the author to the con clusion that the metal liferousso lutio n s were in troduced alon g the dyke fissures . The un oxidizedsulphide ore con sists for the '

most part o f copp er pyrites, misp ickelan d iron pyrites either bran chin g an d in tergrown or fin ely gran ular,accompan ied sometimes by tourmalin e . An in terestin g variety ,

foun d on the Chieftain min e, con tain s magn etite , bo th in the formo f roun d p ellets an d o f threads in tergrown with the copp er pyrites .

The lodes show a very well - marked division in to the three zon eso f oxidatio n ,

secon dary en richmen t, an d sulphide ore . Sin ce thereis n o carbo n ate in the coun try ro ck, the salt p roduced was the so lublesulphate , which was promp tly carried down to the lower levels,leaving the oxidized zon e for the mo st p art free from copp er com

p ounds, excep t fo r the arsen ate o liven ite . This min eral,o n on e

claim,provided quite a large y ield of ore , a fact which con stitutes

somewhat of a curiosity in copp er - min in g .

The zon e of en richmen t in cludes chiefly the min erals tile ore ,

covellite,chalcocite , born ite, and copp er pyrites ; it is of irregul

exten t,but rarely exceeds a depth o f 50 feet below groun d water

level . In the un oxidized p ortion s of the lodes the richer ores are

found in lon g n arrow sho o ts, which may be several hun dreds of feetlo n g , but are on ly from 2 to 6 feet wide in addition to the sho o tsthe lodes con tain large supp lies of low-

g rade o re , which are n ow bein gwo rked on accoun t of the un certain ty and irregularity o f the sho o ts .

A fair amoun t of developmen t work has been don e on the field,

an d a smelter has been erected and worked for several short p eriods .

The p ercen tage o f copp er in the ores after han d - pickin g may rise ashigh as twen ty , but the more usual ’level is about. seven . The greatdifficulty , however, in min in g at a profit is n ot the o re but the costo f tran sp ort to an d from Cairn s, the n earest p ort, which is so highas to make pro fitable workin g o f the min es a verv difficult matter .

W. H. W.

THE KENT COALFIELD : ITS EVOLUTION AND DEVELOPMENT . ByA . E . RITCHIE . pp . x 309 , with illustration s, map s, an d

section s . Iron an d Coal Trades Review,1919 . Price 73. 6d.

THE world at large , and particularly the busier in habitan ts o f

it, owe a great debt to comp ilers, an d this debt is in n o wayreduced by the issue o f Mr . Ritchie ’s book o n the Ken t Coalfield .

The bo ok is the result '

e i the siftin g o f a vast mass o f in formation ,

geo logical , statistical, an d fin an cial,which

,must have been ,

to a verycon siderable exten t

,in such in accessible places as the files of the

daily pap ers and compan y rep orts .

The author treats the subj ect historically ,which is certain ly the

most conven ien t way of p lacin g before us the sto ry which he tells,but

,as geo logists, we could have wished that he had, at an y rate

,

376 Revi ews— The Submerged Forest a t Bombay .

departed for a while from this course' and gathered together thein formation from the various boreho le sectio n s which he gives . Of

course the correlation of coal - seams 1s at presen t quite imp o ssible ,y et with the material n ow in han d it has been found to be possibleto Obtain at least a gen eral view of the broad outlin es o f the structureo f the coalfield . With this criticism we may pass 0 11 to the historicalp art o f the subj ect - matter . The history of the field

, from the earlydays when Godwin - Austen was try in g to co nvin ce an unwillin gpublic o f the existen ce of coal in Ken t, to the presen t stage o f shaftsin kin g an d coal - pr.oducin g , IS admirably to ld, particularly that partof it which 1s co n n ected with the fin an cial tran sactio n s . These , too n e un versed m such matters

,read more like roman ce than sober

fact,but n o less amazin g is the in credible p ersisten cy with which

every on e con n ected with the coalfie ld con tin ued to back thewron g ho rse o n every po ssible o ccasion . Borin gs were put down0 11 wro n g theories, strata highly charged with water were assumedto be quite water—free, shafts were sun k without sufli cien t pump in ggear, in short almo st every wron g assump tio n which could be madeseems to have been made an d '

acted up o n an d y et there is n ow theKen t Co alfield

, a go in g con cern an d o n e which Would be n ow muchmo re active were it n ot for the War an d the threat o f n ation alizationwhich is han gin g over the head o f so much co lliery en terprise .The bo ok is very read‘

ably written ,an d the author is to be co n

gratulated on havin g brought out the first. co n n ected accoun t of thedevelopmen t o f this very in terestin g area

W. H. W.

THE SUBMERGED FOREST AT BOMBAY . By T . H D . LA TOUOHE .

Rec . Geo l . Surv . India ,vo l . xlix, 1919 , pp . 214—19 , with

plates 17 - 19 .

BOUT thirty y ears ,ago man y tree - stump s, submerged about

20 feet below mean sea - level , were discovered durin g the excavatio n o f the Prin ce ’s Do ck , Bombay ,

an d described in the Records,vo ls . xi an d x iv . In 1910 ,

durin g the exten sion of the Alexan draDo ck to the south o f the former site

,more stump s were discovered

an d examin ed by Mr . La Touche . The stump s, 6 or 7 feet high ,were ro o ted in ‘

a thin so il on the surface o f disin tegrated basalt,an d embedded in blue clay ,

which in cluded shells Of Ostrea cucullata‘

with valves un ited . The dep th below high water- mark o f the ro cksurface is about 40 feet

,which gives a min imum value for the total

amoun t o f depression . These two o ccurren ces prove a co n siderablesubsiden ce o f the ro cky flo o r, on the western side o f Bombay harbour,apparen tly within human times sin ce on e o f the stump s seen in 1878was partly burn t This subsiden ce i s in terestin g when con sideredin co n jun ctio n with the well kn own occurren ce o f a raised beachin the same n eighbourho od .

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378 Reviews— Arsen ic an d An timon y .Or es.

masses in the felspar, _ Often in tergrown with co lumbite,mica

, o‘

r

apatite . Man y o f the crystals are un usually large ; o n e crystalfragmen t weighed 500 grams

,an d

'

a so lid mass o f 15 kilo s wasfound ; an average o f three an alyses gave ' 9 95 p er cen t ThO2 .

Co lumbite builds fan —shap ed aggregates in the felspar the crystalsare always sin glv termin ated an d often very large ; on e weighedover 6 kilos .

SPECIAL REPORTS ON THE MINERAL RESOURCES OF GREAT BRITAIN .

Vo l . XV ARSENIC AND ANTIMONY ORES . By H. DEWEY,with

con tribution s by Dr . J . S. FLETT an d G. V. WILSON . Memo irso f the Geological Survey . pp . iv 59

,with 2 figures and

1 p late . 1920 . Price 3s . n et .

HIS, the fifteen th vo lume of this valuable series, gives a com

prehen sive review of the British resources of o res o f arsen ican d an timon y . The ores of arsen ic have n ot been foun d i n n o tablequantity in Britain outside Co rnwall and Devon

,but there the output

is large , main ly as a by-

product in the treatmen t Of ores fortin an d

tun gsten . Of late y ears the to tal production has averaged aboutto n s p er an num o f crude and refi n ed arsen ic

,which is main ly

used in the p reparatio n o f in secticides an d to a less exten t in glassmakin g it is also emp loy ed in calico -

prin tin g , for harden in g leadsho t

,an d in medicin e . All the arsen ic is derived from mi sp ickel .

An in terestin g accoun t is given o f the min esWhere arsen ic is or hasbeen produced in Cornwall an d DevOn ,

in cludin g a useful diagram,

n o t,however

, quite comp lete , of the lodes in East Po o l Min e .The production o f an timon y from the. British min es is almo st

n egligible in amoun t the Glen din n in g Min e, In “

Dumfriesshire heredescribed by Mr .

’

G. V . Wilson,has y ielded a few ton s . Dr . Flett

gives an accoun t o f the an timon y- bearin g vein s o f the Kn ipes Min e ,

n ear New C'

umn o ck,in Ayrshire, which carry stibn ite in un certain

quan tity . In Cornwall the an timon y—be arin g min erals jameso n ite,

bourn on ite, an d tetrahedrite o ccur in small quan tity ,but these

,as

well as stibn ite,are there main ly min eralo gical curio sities .

Rep or ts'

c

’

fc Proceedings— Mi n era log i ca l Society . 379

REPORTS AND PROCEEDINGS.

MINERALOGICAL SOCIETY .

Jun e 15.

— Dr . A . E . H. Tutton, Past Presiden t, in the chair .

F . P . Men n ell Rare zin c - copp er min erals from the RhodesianBroken HillMin e , Northern Rhodesia "

,

Copp er min erals , in cludin gmalachite

,chessy lite, copp er -

glan ce , an d undetermin ed pho sphatesare o f rare occurren ce in the lead - zin c ore of this lo cality . Still rarerare the copp er- zin c min erals aurichalcite an d veszely ite the latterforms min ute , sky - blue

,mon o clin ic crystals (a :b : c “

971

an d differs from the o rigin al min eral from Hun gary in its co lourand in con tain in g little or n o arsen ic .

Professor R . Ohashi Note on the Plumbiferous Bary tes fromShibukuro , prefecture o f Akita

,Japan : This min eral , which is

dep o sited as a white to brown ish -

y ellow crystallin e crust in thefissures and n ear the o rifices Of hot sprin gs , is similar to the min eralrecen tly called hokuto lite

”

f rom Taiwan (2 Formosa) it con tain sto 17

'

78 per cen t o f PbO,an d is radio - active .

W. A . Richardson The Fibrous Gypsum of Nottin ghamshire .

The relation”

to the n odular types of gyp sum of the fibrous vein s of

the min eral which are asso ciated with every other type Of gyp sumdeposit in the district

,an d o ccur at levels where there is n o o ther

deve lopmen t'

of the min eral , was co n sidered . Mo st Of these vein sare regarded as havin g been fo rmed shortly after the n odulardep o sits . The fibres grew upwards and downwards from a p lan e inthe marl

,and were probably deposited by descen din g so lutio n s,

bein g precip itated at p lan es Of ten sion in a con tractin g medium .

The vein s o f fibrous calcium carbon ate or beef ”

described byDr . Lan g show similar structure an d field relation s

,an d doubtless

origin ated under similar con dition s .

W. A . Richardso n :“A n ew Model Rotatin ga stage Petro logical

Microscop e . ” This in strumen t is in tended as a substitute fo r th elarger pre - War models

,which at the presen t time could on ly be

man ufactured at very high prices . It is provided with a mechan icalstage , in terchan geable with a p lan e stage an d a conven tio n al substage , an d provision is made for rap id chan ge from parallel toconvergen t p o larized light . Owin g to the reduction in size a ro tationo f 270 degrees on ly can be provided for the ro tatin g stage .W. Barlow :

“ Models illustratin g the Atomic Arran gemen t inPo tassium Chloride , Ammon ium Chloride , an d Tartaric Acid .

”

In

the case o f the chlorides the suggested structure reco n ciles the X - ray

phen omen a with the crystallin e symmetry . The arran gemen tp rop o sed for tartaric acid agrees with the graphical fo rmula o f thechemists

,an d the mo lecular group s have the symmetry an d relative

dimen sion s of the crystals .

380 Rep or ts (fa Pr oceedi n gs— Geo log i sts

’

A ssoci ati on .

GEOLOGISTS’

ASSOCIATION .

Jun e 4,1920 .

The Theory o f Isostasy z, its geodetic basis an d its ge o-logical

imp lication s .

”

By A . Morley Davies, D .Sc . ,F.G.S.

Plumb - lin e an d p en dulum an omalies . Historical summaryBouguer, Petit, Pratt, Airy .

Static ideas o f“comp en sation become dyn amic in han ds o f

geo lOgists : Osmon d Fisher,Dutto n .

Later geodetic developmen ts Hayford,Bowie ,Burrard . Stren gth

o f the earth ’s crust Barrel], Oldham .

Mistaken app licatio n s o f the p rin cip le o f iso stasy by geo logists .

Great thickn ess o f the shallow - water dep osits , so far from bein g a

con sequen ce o f iso stasy ,in dicate its imp erfectio n . An alysis o f the

case of the Weald .

July 2,1920 .

On the Beds at the Base o f the Ypresian (London Clay ) in theAn glo - Fran co - Belgian Basin .

”

By L. Dudley Stamp , M.Se .,A .K .C. ,

F .G.S.

Bri ef descrip tion o f typ ical section s, showin g the relation betweenthe London Clay an d the Lower Lo n don Tertiaries, throughout theLon do n Basin ” The distin ctive faun a of the Blackheath Bcon trasted with that o f the un derly in gWo o lwichBeds, an d comparedwith that o f the Lon don Clay Basemen t Bed. Recon struction of

geographical con dition s durin g Lower Eo cen e times . Eviden ceof the gradual but in termitten t up lift o f theWeald and its effect o nthe dep osition o f the Eo cen e bedsThe succession in Belgium . Description o f n ew and typ ical

sectio n s , Oldhaven Beds . Clo se relatio n to dep o sits of Lo n don

Area . The succession in the Paris ‘

Basin Remarkable similarityo f geographical conditio n s compared with London . The Sin cen yBeds— the homo taxial equivalen ts o f the Blackheath (Oldhave n )Beds— haVe a similar faun a an d were foun d under similar con dition s .

The succession in the Hamp shire “Basin ”

Co n n exion withParis Basin ”

Faun al n o tes on the Blackheath—Sin cen y Beds .

Summary . The Lon do n,Belgian ,

Paris,an d Hampshire Eocen e

reg i o n s fo rm p arts o f o n e great basin which has a common histo ry .

Essen tial to con sider all parts o f this basin in an y discussion o n

Eo cen e rocks Of o n e region . Blackheath—Sincen y Beds the resul tof the marin e invasion o f Ypre sian times under sp ecial geo graphicalco n dition s . Retain ed as a separate divisio n but part of the Ypresiancycle . Marked chan ge from

'

con dition s of formation o f the un derly in g Lan den ian (Than et Sands, Wo o lwich and Readin g Beds) .

On the Stratigraphical an d Geographical Distributio n o f theSpon ges o f the In ferior Oo lite o f the West of En glan d .

”

ByL . Richardson

,FHRiS.E ,

FG.S

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CorreSp on den ce T W. B . Wright.

presen t dep th [an d width] by pre - Glacial streams . No thin g iseasier than to drawsuch a diagram ; the difficulty comes in provin gthat the Preglacial valley truly had the width and dep th thereassign ed to it . If it had an y such width , its bran ch valley must havehad an accordan t jun ction with it

,but as a matter of fact the bran ch

han gs over the main valley .

’

An addition al diffi culty would be foun din justify in g the assump tion that the profile given for the Sn owdo ncrest an d for a cwm ben eath it correctly represen ts the result o fn ormal ero sion in Preglacial time; y et such an assump tion is made

,

for n o so lid black is added to in dicate that the moun tain profilehas been p erceptibly modified by glacial ero sion .

It 1s then con cluded that accordin g to this in terpretation thetop ography o f Sn owdon at the begin n in g o f the glaciation was

essen tially the same as it is n ow ’’

,an d therefore that glacial ero sion

has been o f small measure . Likethe reticular system of fracturevalleys this con clusion can have little value un til a . n ever -

glaciatedmoun tain district o f altitude Similar to that of NorthWales is foun d,in which the effect o f a sub—recen t up lift in revivin g n ormal erosionhas been to produce huge cwms un der Sharp - edged moun tain crests,and half- mile - wide Side valleys han gin g over still wider main valley s,with vigorous streams p lun gin g down n arrow clefts between thetwo . Moun tain s an d valley s of such forms do n ot exist outside o fdeglaciated region s , and a great body of excellen t eviden ce in dicatesthat their p eculiar forms are the product Of glacial erosion .

W. M. DAVIS .

HARVARD UNIVERSITY ,

CAMBRIDGE , MASS

Re ce n t Sin kin g o f O ce an Leve l .

SIR,— Professor Daly ’

S sp eculation in the Jun e number o f thisMagazin e regardin g the p ossibility of a recent worldwide sinkin go f sea level calls for expo sition o f the facts as regards the BritishIsles . The writer feels somewhat at fault in the matter as he

_

has

made a statemen t of results without eviden ce an d expected it to beaccepted . Un der the circumstan ces Profes'sor Daly can hardly beblamed for settin g on e statemen t again st an o ther, an d con siderin gthat p erhaps the facts may be as required by his theory . It shouldbe p o in ted out

,however

,that there IS n ot really ,

as Professor Dalyhas imp lied,

an y co nfll ct between the writer’s accoun t of the SO - called25 ft . beach an d tho se of S ir A . Geikie 1 an d Hull . As regardsKin ahan

’

s discussio n of the raised beaches o f Irelan d,it can

co nfiden tly be said that what is n ot abso lute error in it is so in defin iteas to have little mean in g . TO

'

him an y thin g served as eviden ce o fa shorelin e , from a glacial corrie or a drift - ban k to a limesto n eescarpmen t . The lowest Of his ho rizon tal shorelin es is by his own

statemen t o n ly 4 feet above mean tide level , so that it is n ot clear1 An n iversary Address to the Geo log ical Society , 1 904 .

Corresp on den ce W. B. Wr ight. 383

how it could be distin ct from the modern shore . His statemen ts,

moreover,do n o t agree with tho se o f Geikie an d Hull .

Now to put the facts as briefly as possible . There are three setsof raised beaches traceable over co n siderable areas in the BritishIsles

, (1 ) the pre—Glacial , (2) the Late Glacial , (3) the Neo lithic(so - called 25 The submerged fo rests rest on the sedimen ts o f

an d are overlain by those o f The Late Glacial an d Neo lithicbeaches are thus quite distin ct . The Neo lithic beach is the bestdevelop ed . It do es n ot o ccur in the South of En glan d an d Irelan d,

where the on ly kn own raised shorelin es are pre Glacial . As regardsthe demon stratio n Of the warp in g of the Neo lithic beach , the writerhas in his p ossession a n o tebo ok con tain in g some hun dreds o f

measuremen ts made by H. B . Man fe an d himself in various partso f the coun try ,

and coverin g in a rough way mo st o f the coasts wherethe beach is foun d . The measuremen ts were made either withreferen ceto a comparable p o in t on the modern shore or to high—watermark

,or to bo th , where bo th were determin able . Man y exten ded

stretches of coast outside the area Of the beach have also beenexamin ed without fin din g an y trace of it . These Observatio n s haven ever been published because of their in comp leten ess . They are

,

however, amply sufficient to demon strate the defo rmation o f thebeach an d its approximatio n to o r disapp earan ce un der sea - levelalon g the p eriphery of its area Of distribution . The exact p ositiono f the zero isobase 1s very difficult to determin e , hen ce the writer sadmission m a letter to Professo r Daly that it might lie furthersouth than shown in the diagram referred to . The average gradien tis o n ly on e or two in ches to the mile .As regards dates , which Pro fessor Daly expressly asks fo r, an d

climatic con dition s, which must 'in terest him,we have fortun ately

some very defin ite facts, which are in agreemen t with observation so n the con tin en t ofEurop e . The beachwas,

fo rmed in Early Neo lithico r Camp ign ian times , and elevated to n early its presen t surfaceIn lateNeo lithic times . Camp ign ian imp lemen ts are foun d embeddedin it 12 feet below the surface

,an d p o lished ston e ax e - heads lie

o n its surface n o t man y feet above presen t high water- mark . Its

faun a indicates a climate some degrees warmer than that of thep resen t day .

With Professor Daly ’

s con ten tion that eustatic movemen ts of

o cean level have taken p lace in recen t geo logical times , the writeris in p erfect agreemen t, but that the latest movemen t has beena n egative on e is n ot supp orted by the eviden ce in this coun try or o n

the con tin en t . Outside the zero isobase of the Neo lithic beach ,in Irelan d, En glan d,

an d Denmark,Neo lithic remain s are foun d

ben eath sea - level,in dicatin g a distin ct p o sitive movemen t . The

widely distributed submerged forests datin g from early Neo lithic.or immediately pre

- Neo lithic times o nwards provide very go od

eviden ce of a gen eral submergen ce . The Very puzzlin g Micmac

terrace,in its horizon tality so un like the p ost - Glacial beaches of

Obi tuary— Georg e Siveet.

Europe, has n aturally led Pro fessor Daly to a differen t con clusion .

Why it alon e Should be un deformed,ly in g as it do es amon g the

highly warp ed sho relin es o f No rth America ,is a mystery which the

tracin g o f it in to o ther areas may ultimately so lve . Its parallelismto the modern Sho re is the more puzzlin g , as Gilbert seems to haveproved that the warp in g o f the Great Lakes Region is

,like that

o f Scan din avia,still progressin g . As regards the very widely

distributed raised shorelin es an d reefs of trop ical seas, the writerhas lon g thought that they are more probably the equivalen t ofthe pre - Glacial shorelin e of Europ e than of an y Of

‘ the later raisedbeaches . Maufe was in clin ed to ho ld the same view when he wasworkin g o n the raised reef at Mombasa . If this is the case

,the con

e lusio n must be that the o cean,after the Glacial o scillatio n s , has

return ed to a level a little lower than that of pre - Glacial times .

W. B . WRIGHT .

DUBLIN .

Jun e 15, 1920.

[We regret that this letter was received too late fo r in sertion mthe July number — ED . GEOL . MAG . ]

'

BOURNEMOUTH CLIFFS .

SIR,

— I have n o desire to pro lon g this discussion ,but as I have

been asked where pho tographs o f the cliffs , as they app eared aboutthirty y ears ago ,

may be seen ,I should like to refer tho se who are

in terested to o n e illustratin g an article on Scien tific Asp ects o f

Bourn emouth ” which appeared in Research of DecemberYours faithfully ,

C. CARUS -WILSON .

OBITUARY.

GEORGE“

SWEET, F.G.S.

BORN 1844 . DIED 1920 .

MR . GEORGE.

SWEET ,who recen tly died at the age of 76, Was born

at Salisbury ,En gland but sp en t most of his life as a man ufacturer

o f p o ttery n ear Melbourn e , Australia . He was a keen geo lo gist,and was ' secon d in comman d Of the secon d Fun afuti exp editionunder Professo r Edgewo rth David He also made exten siveco llection s o f fo ssils from the Carbo n iferous an d Cretaceous stratao f Queen slan d

,an d in vestigated the Permo - Carbon iferous glacial

beds o f Bacchus Marsh . In 1905 he was Presiden t of the RoyalSociety of Victoria .

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RAY SO C IETY ISSUES f o r 1 9 1 7“

a n d 1 9 1 9 .

GROVES (IZ) AND BULLOCK -WEBSTER - (G . R ) . British Charophyta .

Vo lume 1, Nite l leae . p p . x iv + 142 . 20 p late s . Cloth . Lon don ,

1920 . £1 53. n e t .

LUCAS (W. Mon ograph o f the British Orth optera .

'8vo . pp . x ii

264 . With 25 p late s (6 co loured) . Cloth . Lon don , 1 920 . £1 5s . n e t.

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JO HN WHELDO N CO . have th e,larg e st sto ck

_

in the coun try o f Bo oks in a l l

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Li b_ra r ie s o r Sm a l l P a rc e l s P u rc h a s e d .

SPECIAL CATALOGUES Ge o lo g ica l . Bo ta n ica l , Z o o lo g ica l . . En to m o lo g ica l .

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EDITORIAL NOTES

The Nico l Memoria l . (Plate VI . ) 387

ORIGINAL ARTICLES .

Morpho logical Studies on the

Echin o ideaHOlecty po ida . X . By

H . L . HAWKINS . (Plate 393

The Orig in o f Fl in t. By R . M

BRYDONE

The Distribution of British Carbon i ferous Nautilo ids . By th e

o o o o o o o o o o o o o o o

late Dr . WHEELTON'

HIND CORRESPONDENCE .

Inve stigation Of the Mechan ical Pro fe ssor J . E . Marr

Con stitution ofLo o se Aren ace ous R . M , Brydon e

Sedimen ts by the me thod of Pro fe sso rW . M. Davis

E lutriation . By H . A . BAKER . Pro fe ssor T . G . Bo n n ey

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UN IVER S I T Y O P T ICA L W O RKS ,

8 1 TOTT ENHAM CO URT RO A D,LONDO N,W . 1 .

OSWALD (FELIX) , D . so . , F .G .S . A Ge o l o g ica l- Map o f the

Cauca sus . With e xp lan atory text. Comp iled from the late stsource s . Scale 1 : 1 , ,

000 000 (15formation s an d the ign e ous ro cks are cl e arly disp lay ed in twen tydifferen t co l ours . The g laciers are al so in dicated . Al l he ights are

g ive n in En g lish fe et, an d the ' late st rai lway s have be en in serted .

The p amp hl et o f exp lan atory text g ive s a brief accoun t Of the main

phy sical divisio n s o f the Caucasus , fol l owed by a de tailed descrip tion

o f the succe ssive g e o log ical hori z on s with the ir characteristic fossils .

Sp e cial care has be en .taken to in dicate the exact p osition in the

g e o l o g ical serie s at which p etro leum o ccurs in the Caucasian

Oil fie lds .

J US T lS S UED .

GATALOGUEBFzccmsscn WORKSchiefly Orn itho logy an d En tomo logy .

OFFERED FOR SALE av

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C C . , LTD .

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34—36 Marg are t Stre e t, Cave n dish Square , Lo n do n ,W . 1 .

L l S R ARl E S P U R C HA S E D . IN'

T O W N O R C O UNT RY .

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386 Edi toria l Notes .

an d autho r Of numerous bo oks an d papers o n astro n omy an d

phy sics .

a . a: a

DEATH has deprived us Of Professor John Perry ,D .Sc .

,

late of the Roy al Co llege o f Scien ce, South Ken sin gto n (1850who ,with Pro fessors Ayrton an d John Miln e , was amon g

the first o n the stafi o f the Imp erial Co llege of Scien ce , Tokio ,

Jap an ; Pro fesso r o f Mathematics an d En g in eerin g , City an d

Guilds Of Lon do n Techn ica l Co ll ege , Fin sbury ; Presiden t Of thePhy sical So ciety ; fo r man y y ears Gen era l Treasurer of theBritish Asso c1atio n autho r Of numerous scien tific papers, a mo stpopular le cturer, an d beloved by a wide circle o f men Of scien ce .

>z< a a:

THE Min in g In dustry Act, 19 20 , which is the latest version o f the

measure for the establishmen t o f a Min istry Of Min es, has underg on e a good deal of modification in its p assage through Parliament .Some Of these chan ges have to a certain exten t met the Objection sraised in a former issue Of the Magazin e . Thus we fin d that it isn ow p rovided that two advisory committees must be app o in ted bythe Board of Trade , on e to deal with coal , the other withmetall iferous min in g . The con stitution Of the coal committee isset out in detail ; out of a total twen ty - fourmembers on ly on e is

to be a min in g en g in eer , an d there is ,p rOVISIOD for the in clusiono f a n umber of faddists Of various kin ds . There is a delightfulvaguen ess about the clause three [members] shall be p erson s withexp ert kn owledge o f medical or o ther scien ce the italics are

ours . As to the con stitution of the committee on metalliferousmin in g n o thin g is said . Section 21 , subsection 2 , p rovides thatn o in formation with resp ect tO '

an y p articular un dertakin g shal l bein cluded in an y published rep ort . This is a retrograde step , sin cein Section 10 of the Metal liferous Min es Act Of 1 87§ p ower isg iven to the Secretary Of State to co llect statistics, an d there is n o

l imitation Of his p ower to publish them . If this n ew p rovision is

en forced n o details can be g iven as to the output of p articularmin es, as has hitherto been don e , for examp le , in the case o f

hematite min es.

GEOL . MAG . ,1920 .

PLATE VI .

MEMORIAL TABLET EREOTED To

PROFESSOR JAMES NIOOL ,F .G .S ,

“

IN THE UNIVERSITY OF ABERDEEN,1 ST JULY ,

1920 .

Design ed an d executed by A l ice B, Woodward.

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388 The Ni co l Memor ia l .

On behalf Of the subscribers, Dr, John Horn e , addressedthe Prin cipal, Sir George Adam Smith

,as fo llows :

SIR GEORGE,—We have met here to day to do hon our to

Professor James Nico l , who for more than a quarter Of a cen turywas on e Of the teachers Of Natural Scien ce in this Un iversity , an dwho se con tributio n s to Sco ttish geo logy were of the highest value .He was a remarkable examp le o f the best tradition s o f Sco ttishUn iversity life , fo r, in addition to the prime duty of in structin gstuden ts, he regarded the pro secution an d en couragemen t of origin alresearch as an essen tial feature Of the work to be don e by a scien tificdepartmen t .This - memorial is in tended to be a p erman en t record o f the value

o f his con tribution s to the so lution of the problem of the geo logicalstructure of the North -West Highlands . In the first half of lastcen tury that region was visited by Macculloch , Murchison an d

Sedgwick , Hay Cun n in gham an d Hugh Miller, who had describedthe picturesque moun tain s o f red san dston e , overlain by quartzitesan d limesto n es

,in the west Of the coun ties of Sutherlan d and Ro ss .

They recorded that these un altered strata rest up on a p latformo f crystallin e gn eiss an d schist

,and are succeeded eastwards by

metamorphic ro cks that stretch across the Great Glen to the' eastern

bo rder o f the Highlands .

The discovery o f fossils in the Durn ess limeston es in the n orthOf Sutherland (in 1854) by Mr . Charles Peach raised question s Of

Vital geo logical impo rtan ce con n ected with the structure o f thatregion an d the age Of the l crystallin e schists asso ciated with theselimeston es .

Nico l ’s field work In the North West Highlands began in 1855 ,n o t lo n g afterhis app o in tmen t to the Pro fessorship In thisUn iversity .

His first examin ation o f the groun d was carried out in associatio nwith his frien d Sir Roderick Murchison , but all his subsequen two rk was don e by himself

,for they differed as to the in terpretation

Of the structure .Adop tin g the determin atio n Of the fo ssils made by J. W. Salter,the palaeon to logist Of the Geo logica l Survey ,

Murchison referred thequartzites an d limeston es to the Silurian system . He further con

ten ded that as the fo ssiliferous limeston es p assed n ormally belowthe crystallin e schists to the east, therefore these schists themselvesmust belon g to the same system . Hen ce

,with o n e bo ld sweep o f

the brush,Murchison co loured as Silurian the exten sive region

stretchin g from n earDurn essl

to Ston ehaven,and frOm Fraserburgh

to .the Mul l Of Kin tyre . This in terpretation invo lved a radicalchan ge in the geo lo gical map o f Sco tlan d .

Nico l ’s int erpretation was fun damen tally differen t . With um

tirin g en ergy he con tin ued his wo rk in the field for several y earsand issued a series o f papers con tain in g the results Of his researches .

From time to time he modified his views,aban doni n g p o sition s

which he found to be un ten able,and statin g the eviden ce for chan gin g

The Nico l Memor ia l . 389

his Op in ion s . In the developmen t of his researches he showedsterlin g hon esty o f purp o se .His work in the field may be

-

summed up in two proposition s .

First he showed that the red san dston e formation,which he n amed

the TorridOn San dston e was separated from the overly in gquartzites an d fo ssiliferous limeston es by a great un con formity ,

imp ly in g a gap in the geo logical record . This imp ortan t structuralfeature was traced by Nico l for a distan ce Of o n e hun dred mi lesfrom the n orth Of Sutherlan d to Loch Kishorn . Secon d,

he .con

tended that n o con formable upward succession from the fo ssiliferouslimeston e to the overly in g schists is to be foun d . To quo te his ownwords : The lin e o f jun ction

,where this co n formable successmn

is said to occur, is Clearly a lin e Of fracture,everywhere in dicated by

pro ofs Of fracture, con tortio n of the strata,an d p owerful ign eous

action .

”

Such widely differen t in terpretatio n s gave rise to keen controversy .

The progress Of geo logy , like that Of o ther scien ces, is boun d up withco n troversy . The brethren o f the hammer fight keen ly in deed

,

the odium geolog icum rivals at times the odium theo logicum.

Murchison ’

s order o f successio n ,which was supp orted by Sir

Andrew Ramsay ,Professor Harkn ess

,an d Sir Archibald Geikie ,

met with gen eral accep tan ce because it furn ished such a simpleso lution o f the problem .

In 1878 the con troversy was reopen ed an d Murchiso n ’

s positionwas shown ' to be un ten able by several investigato rs, o f whom themost promin en t w as the late Pro fesso r Lapworth ,1 fo llowed byDr . Callaway ,

2 Pro fessor Bon n ey ,

3 Dr . Hicks , an d o thers .

In 1883 the Geo logical Survey began the detailed mapp in g Of

that region . The results Of their work comp letely con firmed Nico l’smain con clusion s .

4 We n ow kn ow that the structure Of thatmoun tain chain is inten sely comp licated,

far more complicatedthan Nico l imagin ed . Un der extreme lateral pressure the ro ckshave behaved like brittle rigid bodies they have sn apped

1 Pro fe ssor Charle s L apworth , The Secre t o f the High lan ds A GEOL .

MAG . ,1 883, pp . 120—8 , 193—9 , 337—44 . On the Stratigraphy an d

Me tamo rph ism Of the Ro cks o f the Durn e ss—Eirebo l l District ” : read at .the

Ordin ary Me e tin g o f the Ge o log ists’Asso ciation , July 4 , 1 884 , by Profe ssor

C . Lapwo rth ; p rinted as read , with a few words added in bracke ts forclearn e ss Of de scriptio n ,

by J . J . H . Teal l , GEOL . MAG . , 1885 , pp . 103 6 .

Profe ssor C . Lapworth , The Cl o se Of the High lan d Con troversy GEOL .

MAG . , 1 885 , pp . 97—1 03.

2 Dr . Cal laway , Quart. Journ . Ge o l . Soc . May , 1881 ; GEOL . MAG . , 1883,

p . 1 39 . Id . , To rridon San dston e an d Ordovician Rocks o f the No rthernHigh lan ds ”

: Q.J . G . S . vo l . xxxvii i , 1 882 , pp . 1 14 1 7 . Id . , Age o f the

Gn e issic Rocks Of the Northern Highlan ds vo l . xx xix , 1 883,pp

3

. 355 4 14 .

Profe ssor T . G . Bon n ey , Litho log ical Character ~o f Sco ttish Ro cks(Dr . Hicks ’ Co l le ction ) : Quart. Journ . Ge o l . Soc . vol . xxxix , 1 883,

pp . 159—66 ; (an d Dr . Cal laway’s Co l lection ) , vo l . xxxix , pp . 414 20 .

4 Drs . B . N . Peach J . Horn e :‘

Pre l imin ary Rep ort on the Ge o logy o f

the Durn ess—E irebo l l District”: Nature , November , 1 884 , vo l . xxxi , p . 1 9 .

TheNi\

co l Memor ia l .

an d h ave . been dr1ven westwards in successive slices,so that

crystalline gn eiss and schist are made to rest up on fossiliferousstrata of Cambrian age . But Nico l ’s main con ten tio n was provedbeyon d doubt that '

there is n o co n formable sequen ce in the No rthWestHighlands from the quartzites an d limeston es in to the overly in gschists. In grapp lin g with the structure of this I

o ld moun tain chainthere can be n o question that Nico l disp lay ed the qualities o f a greatstratigraphist . 1

_

Sin ce the publication o f the results o f the Geo lo gical Survey'work

,that regio n has been visited by man y of the leadin g geo lo gists

in Europ e an d No rth America who have been pro foun dly impressedwith the light which it throws o n the buildin g of an o ld moun tainchain by feldin g an d terrestrial disp lacemen ts .

It is a'

source of gen uin e p leasure to me to presen t this memorialon behalf o f the subscribers to y ou ,

Mr . Prin cipal , fo r the prelimin ary report o n the geo logy o f the Durn ess—Eirebo ll district ,published i n Nature in 1884 by my o ld frien d an d co lleagueDr . Peach and myself, led to the fin al aban donmen t of theMurchison ian hyp othesis .

In the custody o f y ourself an d your successors it will recall . thelabours o f on e whose n amb is in separably lin ked with the so lutionof on e of the great problems in British geo lo gy .

The fo llowin g is a brief abstract o f Professor Nico l ’s life, takenfrom his obituary by Pro fessor Lapworth (Quart . Journ .

“

Geo l . Soc .,

1880 , Pro c .,pp . 33 and may serve to show the. leadin g featuresin

'

his career an d exp lain the s ilen ce which marked the latter y earso f his strenuous life .Mo re than a cen tury ago James Nico l was born at Man se ofTraquair

,Peeblesshire , i n 1810 . His father, the Rev . James Nico l ,

was well kn own for his po etical writin gs . After his father’s death819 , youn g Nico l lived with his family in In verleithen , where

his early education was comp leted by the Rev . Mr . Pate . His

rambles amid 'the bo ld an d p icturesque scen ery o f the district ledhim early to study its geo logy . The absen ce of fo ssils '

an d of clearsection s i n these o ld ro cks directed Nico l ’s atten tio n more esp eciallyto their min eralo gica l asp ect still further en couraged by his

subsequen t atten dan ce o n the classes of Professor Jameson . He

en tered the Un iversity of Edin burgh .

in 1825, where , after passin gthe Arts an d Divin ity courses

,he wen t to German y an d studied .at

the Un iversities of Berlin an d Bonn . On the con clusion of his

Un iversity train in g he return ed to Sco tlan d,an d devo ted himself to

the geo logy of'the valley o f the Tweed,

an d in 1841 he was awardedprizes by the Highlan d Society [

for hi s essay on the Geo logy o f

1Quart.

’ Journ . Ge o l . Soc . , vo l . x ii ,'

1 857 , pp . 1 7—39 , with se ction s ; an dC . Lapworth ,

The ory o f Profe ssor Nico l GEOL . MAG . ,1 888 , p . 1 23.

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392 The Ni co l Memor ial .

tran sferred the '

sphere of his geo logical investigatio n s to themetamorphic rocks

'

of the Highlands , which in 1844 he had suggestedwere probably o f the same geo logical age as tho se o f the SouthernUplands . In 1855 he publi shed his p ap er On the Section s of

Metamorphic and Devon ian Ro cks o f the Eastern Extremity of theGramp ian s (Quart . Journ Geo l . Soc . ,

vo l . xi, p

The same y ear he visited the Well - kn own Torridon and Durn essarea in the North -WestHighlan ds in compan y with SirR . Murchiso n

,

in order to verify Mr . Peach ’s discovery o f fo ssils in the metamorphiclimeston e of that region . On his return he commun icated . an

independen t memoir to the Geo logical So ciety (Quart . Journ . Geo l .Soc . ,

vo l . xiii, p . in which he claims to have published for thefirst time their o rder of succession

, (a) Lower Gn eiss ; _ (b)Conglomerate an d Red San dston e (c) Quartzite (d) Limesto n e ,

“

overlain by (c) an Upp er Gn eiss. Arguin g main ly from the petrographical character of these ro cks

,he threw out the suggestion

that the Torridon Sandston e might be o f Devon ian age , an d that theoverlyin g limeston e an d gn eiss might be '

o f the age o f the LowerCarbon iferous . After Mr . Salter’s demon stration that the fo ssilso f the Durn ess Limeston e were n ot Carbon iferous

,but belon gin g

to the deep est zo n e o f Murchiso n ’

s Silurian ,Nico l again visited the

North -West Highlan ds . In a memo ir givin g the chief results o f thisexp edition (Quart . Journ . Geo l . So c . ,

xvii,p . 85) he retraced his

former admissio n o f an Upp er Gn eiss, sup erior to the Durn essLimesto n e an d claimed to have proved that the lin e of demarca

ti on between the Durn ess series an d the eastern gn eiss of Cen tralSutherlan dshi re is actually a lin e o f fault, the Torridon and Durn essstrata alway s overly in g or abuttin g again st , but n everjdippin g un der,the eastern gn eiss . These op in io n s led to a keen con troversy betweenhimself an d his o ld frien d SirR . Murchison but after the publicatio no f two addition al memo irs o n the subj ect in 1862 an d 1863, in

which he defen ded his view that the cen tral gn eiss o f the Highlan dsis o f the same gen eral geo logical age as the Lewisian gn eiss o f the

Outer Hebrides, an d that the on ly metamorphic strata that cansafely be called Silurian are the less altered ro cks upon the outerbo rders o f the Highlan ds, he ceased to co n tribute pap ers to theSociety up on the subj ect . A little wo rk

, On the Geo logy an d

Scen ery of the No rth of Scotland con tains his last publishedwords up on the subj ect .

as a as at a a

The Clo se o f the Highlan d Con troversy , written by ,Pro fessor

Lapworth (se e GEOL . MAG .

,1885 , pp . 97 an d the admirable but

brief address by.Dr . Joh '

n-Horn e (an te , pp . 388 furn ish a suitable

n o te ‘to Professor Nico l ’s life an d researches,most o f the frien ds an d

con temporary actors in which have n ow,like himself, ceased

from their labours .

”

But the value o f their co n clusion s haveleft a p erman en t impress for go od o n the modern scho o l o fgeo logical thought an d scien ce which can n ever be forgotten .

—H.W.

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394 H. L. Hawlci n s— Echi n o i olea Ho lectyp o i ola .

con strain ed to hop e that the spirit herei-n man ifested may in sp irean ever-

growing'

ecclesia o f in dividuals an d in stitutio n s . A Museumwho se aim is to acquire an d store away a miserly hoard of rarities

’

is in dan ger o f becomin g a mauso leum rather'

than a radian t cen treo f vitality in research the in dividual who fails to welcomediscoveries, even when they might have been his own

,is n o apt

discip le, still less a true ap o stle, of the creed o f scien ce .Of the three sp ecimen s

“

sen t for study O .

"

recen s is. n ow in ruin s(though even y et beautiful) 0 . ep igon us has acquired a co loratio nun like that secreted by an y kn own Echin o id,

an d has un fortun atelylo st its ap ical system while R . caribcearum has suffered removal o fman y o f its radic les . It is my earn est hop e that the fo llowin g n otesmay aton e l n some measure for the damage do n e , an d con vey in themost accep table fo rm my thanks for the promp t an d almost recklessgen erosity that en abledme to investigate material at ‘

o n ce so preciousan d so in terest in g .

2 . APATOPYGUS RECENS (Mi ln e Edwards) .This sp ecies was 1n troduced by

’

Miln e Edwards in 1 836 (Cuvier,Regn . Anim . Z o oph . , pl »x iv,

fig .. under the n ame Nucleo lites

recen s . At that date Nucleo lites was a broad gen eric term coveringal l Irregular Echin o ids which have the p eripro ct o n the adap icalsurface but in this particular case the close sup erficial similaritybetween N . recen s an d such fossil f orms as N . scutatus m

‘

adeapp lication o f the n ame unusually appropriate .

_

D’

Orbigny in 1854

(Rev . Mag. Zo o l . ) automatically rep laced Nucleo lites by the preLin n ean Echin obrissus, but n o reason ed attemp t at better gen ericprecision was made un til 1889 , when Dun can (Journ ; Lin n . So c .

,

vo l . xxii) prop o sed Oligop odia as a subgenus , in cludin g the . two recen tsp ecies o f Nucle o litidae then kn own

,recen s and ep igon us . In 1904

Haman n (Bron n’

s Thierreichs) raised Oligop odia to gen eric ran k, an drestricted it to ep igon us (Marten s) , which thereby became thegen o typ e . Echin obrissus recen swas left in NucleolitesbyHaman n ,

but Clark (19 17, Hawai ian and other Pacific Echin i , p .

believin g recen s an d ep igon us to be '

co n gen eric, an d quitedifferen t from typical Nucleo lites of Lamarck

,

placed both un derOligop odia .

While con currmg 1n Clark’s op in ion that both are in capable o fbearin g the n ame Nucleo lites, I am fully con vin ced that they are so

far from bein g con gen eric that family ,and in deed o rdin al , distin ction s

separate them . The reason s for this belief are Subjo in ed, but thesystematic sequel can be ind1cated here . Nucleo lites ep igonus

Marten s is the lecto -

ge'

n o typ e (Haman n,1904) o f Oligop odiaDun can ,

1889 . Nucleolites recen s M. Edwards is certain ly n o t a Nucleolites

in the accep ted sen se o f the term ,an d 1s even less akin to O. ep igon us .

A n ewgen eric n ame is thus n ecessary forN . recen s , un less that sp eci escan be“ shown to belo n g to some o ther genus already diagn o sed .

The latter condition do es n o t obtain,so far as I can determin e ,

H. L . Hawlc i n s— Echino idea Ho lectyp o i ola . 395'

so that I hereby establish the n ew genus Ap atoyoygus,1 whose gen otyp e an d o n ly kn own species is Nucleolites recen s Miln e Edwards ,1836 . A detailed diagn osis o f the genus

“

con cludes this sectio n of

the paper .

The descrip tion of Ap atop ygus recen s (sub Echin obrissus) givenby A; Agassiz (Revision , pp . 556—7) is sufficien tly full an d in

agreemen t with the specimen befo re me to serve with but littlecommen t . The descrip tio n o f the

'

p‘

eristome and its surroun din gsis accurate, but Agassiz’ use o f the term phy llode might provemisleadin g . There is n o more trace of phy llodal qualities, whethero f platin g or p ore - disp ositio n ,

in the o rad parts o f the ambulacrathan o ccurs in an ordin ary Spatan gid . The proximal pores are

appreciably larger than the o thers, an d tend to perforate theirambulacrals in themedian lin e rather than n ear the adradial suturesbut the pores show less ten den cy towards triserial arran gemen tn ear the peristome than on the rest o f the adoral surface while thep latin g is almo st p erfectly simp le and Cidaro id

”

in the region wherethe pores in crease in size . With regard to the in terambulacralparts o f the p eristome - margin ,

there can be n o doubt that Agassiz’remark that n o buccal bourrelet had been develop ed is an

under- statemen t . As far as such a con dition is con ceivable it maybe said that bourrelets are positively absen t— the proximalin terambulacrals are excep tion ally thin in their invagin ated parts,resemblin g tho se o f Echin on e

‘

us more than those of an y o ther recen tEchin o id with which I am acquain ted

,an d exceedin g them in

delicacy . The quality expressed in the gen eric descrip tio n (10 0 . cit .

p . 556) Flo sce lle rudimen tary ; n o well - marked bourreletswould, to my mind, be better abbreviated to the bare statemen tn o flo sce l le

The n ature of the ambulacral platin g , which is roughly in dicatedin Agassiz ’ figures, but n ot men tion ed in the text, seems to me to

provide the mo st unusual an d distin ctive feature in A . recen s .

An alyses of on e of the lon gest areas (I ) and the shortest area (III )are here given (PlateVII, Figs . 1 and As far as in dication s go ,

area II (which is almost midway between the extremes in po in t o flen gth) resembles the latter. more clo sely than - the fo rmer . In al l

ambulacra,practically the en tire exten t o f the adoral parts (excludin g

the peristomial p o rtion s above men tion ed) disp lay typically“Pyrin id

”

p latin g (see Hawkin s, Phil . Tran s ,the d emi

plates o ften un dergo in g great reduction . In area I this conditionceases just below the ambitus, an d the adapical part of the area isbui lt of simp le p rimaries

,some o f which (below the p etals) may be

almost half as high as broad . The p etal con sists of thirty p latesin each co lumn

, p erforated by dissimilar p ore - pairs . In area III ,Pyrin id structure p ersists up to , an d even in to , the p etalo id regionwi th characters in distin guishable from tho se presen t adorally .

1 awar dw, I dece ive , an d -

p ygus , n o rmal suflix fo r g e n era of this group .

396 H. L. Hawki n s— Ech'

i n o idea Ho lectyp o i da .

There are twen ty - on e o r twen ty - two p lates in each co lumn of thep etal . Three or four of the distal p lates of this region show in cip ien tPyrin idg roup in g, while a triflin g imp erfection o f altern ation affectsbo th co lumn s quite n ear the ap ex .

“

(This last may well be but - an

individual irregularity . ) The in dication s o f structure given in

Agassiz’ figures are therefore con firmed (broadly sp eakin g ) ; but

he represen ts Pyrin id p latin g as con tinuous to the p etals in all five

areas,while it certain ly do es n ot e xtend above the ambitus in areas

I and V in the specimen before me,

-

an d seems n ot to reach the petalsin II an d IV.

The two features described above co n tain sufficien t eviden ce forgen eric separatio n of A . recen s from 0 . ep igonus (Pl . VII, Figs . 3an d

although man y o thers could be cited . In the latter sp ecies thereis a p erfectly defin ite flosce l

’

le , with expanded (though structurallysimp le) phy llodes an d well - marked, typ ical in terambulacralbourr 'elets . There is n o trace o f ambulacral comp lexity above thephy llodes ; all ambulacrals between these an d the petals are aboutas high as broad

,an d in con sequen ce the n umber of podial pores

is very small . All five p etals are o f the same len gth, an d con tainthe same number of p lates while the p etalo id pores are large an dp erfectly similar . The n ame Oligop odia is emi n en tly appropriatefor epigonus, but itwould be gro tesque to app ly it to recen s , wherethe n umber o f ambulacral p lates (an d p odia) is vastly in excess of

exp ectation for so small a form . 0 . ep igonus is a typical Cassidulcid an d resembles Rhyn chop ygus an d Echin o lamp as in

ambulacral characters,as in man y o thers . As Agassiz remarked,

it is closely similar to the Cretaceous gen us Caratomus . Theaffin ities o f Ap atop ygus will be discussed in the n ext section ,

but

a diagn osis of the genus is n ow p o ssible .APATOPYGUS gen . n ov .

,Hawkin s, 1920 .

Gen o typ e an d so le sp ecies, Nucleolites recen s,M. Edwards, 1836 .

Nucleo lito ida,Nucle o litidae . Test depressed, subquadrate, with

greatest width behind the ap ex . Ambitus roun ded,adapical surface

risin g to a low,almo st median summit ; a

_

doral surface slightlytumid, stron gly invagin ated at the peristome . Ap ical system

eccen tric an teriorly ,built o f five small o culars an d four gen itals, o f

which the madrep oric p late occup ies the cen tre o f the system,an d

just separates the p o sterior o culars . Peristome deep ly invagin ate ,eccen tric an teriorly ,

tran sversely ellip tical , with thin margin al plates .

Perip roct lon gitudin ally ellip tical , situated in a deep sulcus to whichit forms the ap icad wall , about midway between the apex an d the .

p osterio r margin o f the test . Anus surroun ded by a man y-

p latedmembran e

,the largest plates bein g p osterio r an d extern al . In ter

ambulacra wide,built of fairly low p lates ben t n ear the median lin e

o f each co lumn . Proximal orad in terambulacrals large, sin gle , an dvery thin . Tubercles large for a Nucleo lito id,

scrobiculate , imperforate arran ged in quin cun x o n apicad and'

orad plates . Ambulacra

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398 H. L . Hawhi n s— Echi n o idea Ho lectyp o i da .

app ear to o scillate (save p erhaps for steady reduction in theexp an sion of the p etals) , phy llode - developmen t seems to s howprogressive (or, p erhaps, regressive ) _

modification . The p latecomp lexi ty that was con cen trated in to the true phy llodes of theo lder Nucleo litids (such as

'

Galerop ygus and Nucleolites quadratus)spread gradually away from the p eristomial region un til in area IIIo f .Ap atop ygus it invo lves the greater part o f the area in triadgroup in g . As far as phy llode - production is con cern ed,

the " chan gewas catagen etic, but in resp ect '

of the complexity of the who leambulacrum it was clearly an agen etic .

The sequen ce of ambulacral morphogen esis in dicated above wascarried out in a series o f fo rms who se gen eral evolution has beenrelatively static . Save for its ambulacral platin g , Ap atop yguswould n ot have been out of place on a Middle Jurassic beach .

An o ther lin e of d escen t from the Galerop ygus—Nucleo lites stock ledin quite an opp o site directio n ,

an d produced the Clyp eus—Pygurusseries with in creasin gly complex an d limited phy llodes . Thatessen tially Meso zo ic group showed far more diversity 1n form

,size ,

an d detail than the con servative Nucleo litidae , an d paid the pen altyo f over- exuberan ce by extin ction

“

in the Cretaceous period . The twoNucleo lito id series thus provide clear illustration o f the prin cip leso f evo lution already familiar in man y phy la . In comparison withBrachiop oda,

Ap atoy ygus may be said to bear a similar relation toGalerop ygus to that born e by Lingula to Lingule lla while Pyguruswould agree more with Sp irifer . The persisten t Nauti lus and theextin ct Ammon ites have comparable histories .

The ambulacra o f Ap atop ygus invite comparison with tho se of theEchin on e

'

idae . Save for the presen ce of p etals an d bip orouso rad ambulacrals

,A . recen s has typ ical Pyrin id ambulacral p latin g ,

almost p erfect as far as it exten ds . In area I (Pl . VII, Fig . 1 )there o ccur three Disco idi id triad -

groups (simi lar p lates appearin Trematop ygus) , so that the correspon den ce with Ho lectyp o idstructures is emphasized . It seems quite in con ceivable that an yphy letic lin k can con n ect Ap atop ygus with Pyrin a o r an y o ther lateHo lectyp o id ; so that the app earan ce of Pyrin id p latin g in the .

recen t fo rm must be ascribed to parallel developmen t .If o rthogen esis supp lies an

'

exp lan ation of this co in ciden ce , theseparable qualities o f the compon en ts of individuals is striking lyillustrated . The ambulacra o f Ap atop ygus have come to co n form

to the Ho lectypo id standard in essen tials (albeit by a n o n

Ho lectyp o id route) ; while o ther co ron al structures have fo llowedquite differen t lin es of developmen t . Further, the a pp earan ce ofPyrin id p latin g in the last o f the Nucleo lito ida seems to give supportto the belief that that sto ck bran ched from the Ho lectypo id series(though early ) rather than aro se in depen den tly . That exten sivetriad-

groupin g o r combin ation after this pattern app eared l n LowerCretaceous times in the Echin in a

,Echin on

'

éidae,Lan ieriidae , an d

Nucleo litidae,is a co in ciden ce explicable on ly on the assumption

H . L . Hawki n s— Echi n o i dea Ho lectyp o ida . 39 9

that morphogen esis may be n ot merely parallel in o therwisedivergen t sto cks but pro ceeds at the same rate . Hen ce comemodes or

“fashion s prevalen t in ultimately homogen etic

s eries— sources o f con ven ien ce to the stratigrapher an d con fusionto the systematist .

4 . THE AFFINITIES OF ECHINOL AMPAS.

H. L. Clark (Hawaiian and other Pacific Echin i , p . com

men tin g on my suggestion that the Nucle o litidae (i . e . theCassidulo idea of Sladen an d Astern ata o f Gregory ) may bediphy letic, states that “ the recen t sp ecies seem to form a veryhomogen eous group ;. but he admits that amore n atural group in gin accordan ce with some of [my ] suggestion s may prove p o ssible .The earlier section s of this paper seem to me to show that Ap atop ygus,at least

,is a very distin ct~typ e from the Oligop odia—Rhyn chop yyus

Echin o lamp as series o f recen t Cassidulo ids . Ap atop ygus has

defin itely dissimilar petalo id pores— tho se o f the Cassiduloida are

similar an d n ormally con jugate . I have n o kn owledge o f an y o therlivin g genus that can be asso ciated with Ap atop ygus in theNucleo lito ida, and so agree with Clark as to the apparen thomogen eity of his Nucleo litidae with this sin gle excep tion .

In several of the papers in this series, an d esp ecially in my recen tmemo ir on ambulacra (Phil . Tran s ) , I have argued that theEchin o lamp as

- series (which I call Cassidulo ida sen s . str . ) are

sequen tially related to the early Echin on e idae much as theClypeastro ida are to theDisco idiidae . In the almo st comp lete absen ceo f kn owledge o f p ost - larval chan ges in recen t Echin o ids (zoo logists,p lease n o te l), my argumen ts have n ecessarily been somewhathyp o thetical or based on un verified assumption s . But in thesection of Agassiz ’ Revision On the y oung stages of Echin i(Part IV) , p . 741 , an d in the plate (xvi) illustrative of the particularparagraph , somethi n g approachin g on togen etic pro of o f my con

ten tion app ears . Agassiz say s The developmen t o fEchin o lamp ashas thrown un exp ected light upon the affin ities o f the to o thlessGalerites an d o f the Cassidulidae . It shows c on clusively thatEchin on éus is on ly a perman en t embryon ic stage of Echin olampas,thus becomin g allied to the Cassidul idae, an d that it has n othin g incommon wi th the

.Galerites as I would limit them

, con fin in g themen tirely to the group provided with teeth .

” These sen ten ces werewritten lon g before Agassiz was able to record the presen ce of a

vestigial lan tern in youn g Echin on e'

us- in the light of that discoverythe genus has almo st every thin g in common

'with theHo lectyp o ida . Study of Agassiz ’ drawin gs (p l . xvi, figs . 1—3) showsthat Echin o lamp as dep ressa ,

when 4 mm . in diameter, is more likea Conulus or Globator than an Echin on e

'

us in gen eral facies, buthas the tuberculation of a Discoidea . At a later. stage, 12 7mm . in

diameter (tab . cit .,figs . 8—10, here p artly adap ted,

Pl . VII,Fig .

the test takes on a more depressed an d elon gate form,an d the

400 H . L . Hawki n s— Echi n o idea Ho lectyp o i ola .

tuberculation becomes amp lified in the hour-

glass patterncharacteristic o f Oon ulus . (In E . stern oy etala Ag . Clark

,

Con ulus - tuber‘

culation seems p ersistent even in the adult . ) Itis in the ambulacra , however, that the y oun g Echin o lamp as exhibitsthe mo st remarkable qualities . Agassiz says o f these p .

each plate carries a sin gle p rimary tubercle The p o resare arran ged three or four for each p late . His en larged drawin gs(here Pl . VII, Fig . 5) show that each p late is really a triad—group .

No in dication app ears as to the relatio n s o f the comp on en ts of thegroups, but that they are n o t all primaries seems probable from then ature of the p erradial suture . In view o f Agassiz ’ previ ouslyquo ted remark

,it i s reaso n able to assume that the triad -

group s

are Pyrin id in character,like tho se o f Echin on e'us . Such triadic

structure is p ersisten t in Amblyp ygus (otherwise very n early akinto Echin o lamp as) , but it is n ot retain ed in adults of Echin olamp as

itself. Its p resen ce in early o n togen y must sure ly be vestigial .In con sequen ce the descen t o f the Echin o lamp as—sto ck from an

Ech’

in o n e'

id (o r late Ho lectypo id) ancestry is a con cep tion that isn ow so far established that it is for tho se who disagree to disprove it .Stratigraphy ,

morpho logy ,an d n ow on togen y , all po in t to its truth .

The ambulacral history o f the Nucle o lito ida an d Cassidulo ida

(assumin g the above co n clusio n s to be accurate) shows a stran ge ‘

course o f morphogen y . The phy letic relatio n s of the group s , as

they appear -to me,can be in dicated thus

Lower Jura I Upp er Jura I Cretace ous I TertiaryClyp

-eus Pygw us Nucle o l ito ida .

pa top ygus

P lesiechin us

Py gaster~ Echin on

‘

e‘

us Ho lectypo ida .

E chin o lamp as Cassidulo ida .

‘The Nucle o lito ida early acquired elaborate phy llodes, retain in gsimp licity in the rest o f their ambulacra . Durin g the Meso zo ic era

their phy llodes un derwen t gradual decen tralization ,un til triad

group in g affected a large part of the areas . Thi s tenden cy culmin atesin Ap atop ygus . On the o ther han d

,the Ho le ctyp o ida failed to

develop phy llodes, but progressively Spread triad -

group in g overtheir ambulacra (e .g . Pyrin a In the Tertiary era ,

simpl ification o f p latin g, coup led with production o f well defin edphy llodes (p erhaps foreshadowed in Oon ulus) , characterized theCassidulo ida . The two indep ende n t tren ds separated rap idly inthe Lower Jurassic

,and then slowly converged un til, in the

Cretaceous,they were almost co in ciden t . Modern Cassidulo ida

have reached a stage an alogous with that of the precocious Clyp eidaeo f the Nucle o litoida . But Ap atop ygus an d Echin on

'

e’

us remain as

sup eran nuated survivors,the last of their resp ective orders,

weari n g to - day the ambulacral fashion s of the Cretaceous period .

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402 R . M. Br yolon e— The Or ig i n of Fl i n t.

irreco n cilable with an y theory but that o f the flin ty en velop e bein gpractically con temp oran eous with the chalk ,

the flin t vei n s,some

o f which are n early at right an gles to the stratificatio n, seem

to be irrecon cilable with an ythin g like con temp o ran eous origin .

Mr. Richardson states that there is n o difference between the ‘

two

types o f flin t (i . e . the bedded an d the vein flin t) . Chemically an d

op tically that has presumably been established for some vein or

vein s ; but un less cavities con tain in g p owder, or who lly en clo sedfo ssils, are common ly foun d in vein flin t

,and vein flin t common ly

occurs with a thick cortex,n on e of which thin gs are within my

experien ce , the statemen t can hardly be accurate as it stands .

A factor o f con siderable importan ce en tirely overlo oked byMr . Richardso n IS to be foun d In the marl seams so abundan t m theflin ty chalk . These must be more imp ervious than the chalk, an dwould n aturally ho ld up an y downward diffusin g or drain in g so lution .

But the relation ship between marl seams and fli n t rows to whi chthi s would n aturally give rise on Mr . Richardson ’

s theory ,1 . e . marl

seams co in cidin g with or just below flin t rows,is almost unkn own In

practice . On the o ther han d, an y advo cate of a precip itation aftergravitation theory might we ll app eal to the abso lute freedom from

marl seams o f the great thickn ess of Than et Chalk, xwhose silica ,

accordi n g to him,is n ow aggregated in to the Three In ch ban d,

and might also app eal to the dissemin ated marl in the Lower an d

Middle Chalk as the reason why n o drain age aggregation of silicato ok p lace there . In ciden tally it may be observed that the soft,sp o n gy , dark -

grey flin ts which are so abun dan t at Trimin ghamare characteristic of the marly chalk .

It 1s n ot safe to place much relian ce on Mr . Richardson ’

s table(No . 2) of silica con ten ts . He budgets there for n o less than twen tytwo lay ers o f 3 in ches or mo re in thickn ess

,con tain in g 100 per cen t

o f silica . When it is con sidered that the un ique “ Three In chban d IS n o more than a lay er 3 in ches thick con tain in g 100 p er cen to f silica, it will be seen how misleadin g an estimate must be which i sbased on the assumed presen ce of twen ty - two Three In ch ban dswithin the zon e o f M . coranguinum in Than et (to say n othin g o f anassumed 12 in . ban d of so lid silica in the zon e of Marsup ites) . Hehas further budgeted for thirty lay ers o f 3 in ches, con tain in g 50 p ercen t o f silica, and therefo re each the equivalen t of a tabular 1 in chesthick . If he will con struct to scale an y con ceivable section o f a

lay er 3 in ches thick, o f which 50 p er cen t shall be flin t, he will se eat on ce that such thin gs are extremely rare in the Chalk,

’an d that

there can n o t p o ssibly be thirty of them in the Ken t Coast sectionin addition to twen ty - two Three In ch bands .

In his Fig . 4 he shows the mucron ata chalk o f Dorset as flin tless,and in the text he states that in the mucron ata zon e the flin ts aregen erally small an d immature . I do n o t kn ow what his authorityis, but I can assure him that at Studlan d, at an y rate , the mucron atachalk -

of Dorset is by n o mean s flin tle‘

ss,but con tain s stron g rows

R . M. Bry olon e— The Or ig i n of Fl i n t. 403

o f massive and fully mature flin ts ; so do es the mucron ata zon e inthe Isle ofWight at Alum Bay ,

and the mucron ata zon e of Norfo lkon the Weybourn

—‘Cromer coast, an d also at Trimin gham (in thewhite chalk) .An o ther p o in t n o t touched on by Mr . Richardson is the frequen cy

o f horizon tal un iformity in variation s in the flin ts . Take, forin stan ce

,the fli n ts of the upp er part of the zon e o f M . coranguinum

in Han ts . In p rop ortion as the Uin tacrin us—ban d is approached,the

white cortex en croaches on the clear in terior an d assumes a p in ktin ge, un til the broken flin ts show n o thin g but pin k cortex wi thoutan y clear cen tre ; an d then it is time to lo ok very closely forUin tacrin us if it has n ot already been foun d . Or take again thespo n ge - bed at Trimin gham, which always has above an d below ita bed o f lo n g slen der flin ts like n o o thers that I have seen . Suchcases as these are much more suggestive o f progressive formationo f flin ts under vary in g con dition s o f the sea bo ttom than o f

simultan eous formation throughout man y hundred feet of chalkin a more or less un iform set of con dition s .

Mr . Richardson ign ores the eviden ce of fo ssils, but there are

several indication s to be drawn from them . In the first p lace thereare in the Chalk million s of specimen s of Echin ocorys perfectly filledwith chalk . The on ly avenues by which this chalk could en ter are

the relatively minute ap ertures o f the mouth an d ven t . It 1s clearthat the o o ze in which these shells were immersed after the an imal’sdeath must have been exceedin gly fluid

,practically . liquid . With

these chalk - filled Echin ocorys there o ccur million s of Echin ocorys

p erfectly filled with flin t, y et havin g n o vestige of flin t on theiroutsides . Occasion ally specimen s of Echin ocorys are foun d in whi chthe in terior is partly filled with chalk an d partly with flin t . In thesecases there is always a defin ite boun dary between the chalk ,an d the

flin t . I have n ever seen an y indication of sp oradic silicification in

the -

chalk in side an Echin ocorys . These con sideration s seem irrecon cilable with an y metasomatic theory of the origin o f the flin t .In a medium so fluid as the oo ze is shown to have been

,n othin g

could have preven ted it from fillin g those Echin ocorys which are'

n ow silicified, excep t the presen ce o f the dead body o f the an imal .As that decay ed it must have been rep laced by o o ze un less the silicahad already in stalled itself, and silica arrivin g at an y later datewould have foun d these Echin ocorys comp letely filled wi th o o ze .How are y ou go in g to arran ge in a more or less con so lidated deposit(on the uplift drain age theo ry a dep osit hun dreds o f feet 1n thickn essand almo st n ecessarily con so lidated) for the con cen tration on thetwo small ap ertures '

of a small proportion o f the Echin ocorys presen tin the chalk of streams of silica of exactly suffi cien t force , purity ,

co n tinuity ,an d vo lume to disp lace every particle of chalk from the

in terior o f these Echin ocorys without the very slightest overflow o f

silica The con clusio n that the silica got there before the oo ze hada chan ce seems irresistible . It isn ot difficult to see that the distin ction

404 R . M. Br ydon e— The Ori g in of Fl i n t.

between the chalk - filled Echin ocorys and the flin t - filled Echin ocorys

might be due to the fo rmer havin g at the death o f the an imal cometo rest with the apex downwards an d the mouth and ven t exp osedso that the dead body was cleared out by an imalculae and n o t leftto decay ,

while the latter came to rest with the apex upwardsand the mouth and ven t pressed in to the o o ze , so that the dead bodywas . left to decay an d provoke the dep osition o f silica .

Again , the po ssibility that the flin ts were formed at the surfaceof the o o ze can be written o ff altogether on fossil eviden ce ,The Chalk sea was full o f en crustin g an imals, such as Sp ondylus

latus,Ostrece

,Serp uloe, an d Porosp hcerce . I have n ever seen a

case,an d I do n ot kn ow o f on e havin g been recorded o f an y

o rgan ism bein g foun d en crustin g a flin t,though that must have

happen ed freely if they had existed at the surface o f the o o ze .It is rather surprisin g that the suggestion should ever have beenmade

,for it must be plain that as so on as a particle of flin t

had formed at the surface it would, owin g to its specific gravity ,

sin k' out o f sight at on ce in the practically liqui d o o ze . It wouldpresumably sin k to such a dep th as the co n so lidation o f the o o ze ,n aturally in creasin g with dep th , would admit, and might there fo rma nucleus for con cretion ary growth o f a flin t . All particles o f flin tarisin g at the surface of the o o ze about the same time wouldpresumably sin k to about the same depth

,which might quite well

be below the ran ge o f a dredge, _and would give rise to a row o f

flin ts roughly parallel with the surface o f the oo ze, i . s . pseudostratified . A question here suggests itself which I am un able toan swer, i . e . whether the sp ecific gravity of a so lution o f silica mightbe sufficien t to produce the same result by a con cen tration o f thesilica in so lution at some depth below the surface of the o o ze wherep recipitation would o ccur

,an d the n ewly precipitated flin ts would

then sin k to their n atural static level .Again , it is a well kn own thin g that fo ssils o f all description s are

frequen tly embedded in flin ts . I have n ot made an y express test,but it i s my stron g Impressio n that fossils are much more abun dan tat the p eriphery of flin ts than at an y o ther in ternal con tour lin e ,or

, indeed in the who le of the in terior . It is possible to regard theseextern al fo ssils as havin g con tributed to determin in g the outlin eo f the flin ts by some p ower o f attraction of the growin g amorphousmass of co llo id silica ,

an d the most likely cause of such an attractio nwould be the presen ce on them o f decay in g an imal matter

,which

woul d invo lve pen econ temporan eous formation of the flin t ..Again , as I have in dicated above

,the con ten ts o f ho llow flin ts

afford a stron g argumen t for the con temp oran eous or

'

p en econ~

temporan eous origin o f these flin ts,at an y rate .

On the who le a pen econ temp oran eous origin for row an d tabularflin ts seems to presen t the min imum of confli ct with facts, while thevein flin t is obviously o f some subsequen t date at or after theformation of the up lift cracks which - it o ccup ies .

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40 16I

i“

“

Dr .

“

Whee lton Hind

UPPER CARBONIFEROUS LIMESTONE

Temn ochei lus coron atus M‘

Coy .

derbi ens eHin d .

costato - coron atus M‘

Coy .

_

P leuron auti lus scarlettensis Re id.

Ep hipp ioceras bi lobatum Sow .

Stroboceras su lcatum J . de C.,Sow .

bis-ulcatum de Kon in ck .

Dis'

citoceras levei l lean um de Kon in ck .

wrighte i Fo ord .

Ap he leceras latum Hin d .

Vestin autilus crassimargin atus‘

Fo ord.

LOWER CARBONIFEROUS LIMESTONE (p robably Can in ia ) .

Trigon oceras p aradox icum J . de C. Sow. V. p aucicarin atus Fo ord .

D iscitoceras l evei l leanum do Kon in ck : mu lticarin atus J . de C. Sow .

discors M‘

Coy . Cwlon auti lus doohy len sis Fo ord .

costel latumM‘

Coy . gradus Fo o rdr

Apheleceras mutabi leM‘

C'

oy . P lan etoceras g lobatum J de C. Sow.

hibern icum Fo ord Crick: Co loceras coyan um d’

o rbign y .

discus Sow .

“

bistriale M‘

CoyM esochasmoceras latidorsatum M‘

Coy . Thrin coceras kyatti Fo ord:D iorugoceras p lan

'

idorsatum Portlo ck . hibern icum Fo ord.

Tribo loceras formosum Fo ord“

. A ip oceras comp ressum Fo ord .

Vestin auti lus s emig laber Fo ord . A symp toceras crassi labrum Fo o rd

c‘

arin iferus J . de C. Sow . foordi Hy att .

crateriformis Fo ord . So len ochei lus dorsa lis Phill ip s .

p in ga is de Kon in ck . hibern i cus Fo o rd .

TEMNOCHEILUS M‘

Coy ,1844 .

Typ e— T . coron atus M‘

Coy , Syn . Carb . Foss . Irelan d .

Temn ochei lus coron atus M‘

Coy .

—Upp er Dibun o phy llum zo n e.Lowick

,Northumberlan d ; Parwich an d Castleton , De rbyshire

Stebden Hill,Yorkshire . Little Islan d

,co . Cork, Ireland .

“Visé ,Belgium .

T . tuberculatus Sow . ,

'

1821 .

—Dibun ophyl lum zon e to Lower Coalmeasures . Lower Coal - measures

, Shibden an d Hal ifax,Yo rkshire

Sabden Shales,Rough Lee , Lan cashire ; Silica Quarry ,Co n gleton

Edge (z Sabden Shales) , Cheshire . Closeburn ,Dumfriesshire ,

Sco tlan d .

T . con cavus J .

-de'

C. Sow. ,1840 .

— Coal - measures . Coalbro okdale ;N. Staffs ; Lan cashire . S. Wales .

T . carbon arius Fo o rd,1891 .

—e Coal - meas'

ures . Coalbro okdale ;N. Staffs ; Lan cashire .T . derbien se Hin ds—Upp er Dibun ophy llum zon e . Tissin gto n ,

Derbyshire .T. crichi Fo ord — Described in the Catalogue o f the Natural

Histo ry Museum f rom Ireland but without an y defin ite lo cality .

Was ign ored by Fo ord in his later mon ograph .

T, c

'

ostato—coron atus M‘

Coy .

i 4 Laws Limeston e , Lowick,Ncrthumberlan d .

T . tuberosus M‘

Coy—

\

Derby shire .

—UPPER DIBUNOPHYLLUM ZONE .

Coelon auti lus p lan otergatus Phil lip s .

Co loceras bistri-a le M‘

Coy .

Thrin coceras luidi i Martin .

So len ochei lus ca ledon icus Fo ord .

cyclostomas Phill ip s .

clausus Fo ord .

crassiven ter de K on inck .

infun dibu lum de Kon in ck .

in gen s Martin .

derbi en s is Fo ord .

Distr ibu tion of Br i ti sh Carbon iferous Nau ti l o i ols . 407

TRIGONQCERAS M‘

Coy , 1844 .

Typ e .

- T . p aradox icum J . de G. Sow. ,1825, Min . Con ch .

,vo l . v,

p . 81 , p l . cccclvii .

Trigon oceras p aradox icum J . de C. Sow— Carbon iferous Limeston e ,Cl . St . Do o laghs, co . Dublin Clan e

,co . Kildare Rathkeale an d

Do ohy le , co . Limerick ; Cork, Irelan d . Fide De Kon in ck,Visé

,

Belgium .

PLEURONAUTILUS Mojsisovics .

Pleuron auti lus falcatus J . de C. Sow .—Coal—measures . Ro sser

Vein s, Glan Rymn ey , S. Wales ; Pen n yston e , Shropshire . Millston eGrit (Sabden Shales) , Sale Wheel, River Ribble , Lan cashire .P . armatus J . de C. Sow.

—Coal—measures . Pen n yston e , Shropshire .P . costatas Hind .

—Coal—measures . Below Gin Min e Coal , N.

Staffs 705 feet above the Barn sley Coal at Brodswor‘th, Yorkshire .P . p ulcher Crick — Millston e Grit to Coal - measures , Sabden

Shales hori zon ,Horsebridge Clough, n ear Hebden Bridge 71 feet

below the 4 ft . Coal, Cheadle , N. Staffs .

P . rotifer Salter .

—Thi s sp ecies is probably iden tical with P .

falcatus J . de C. Sowerby . 150 yards above the Great Min e . Coal ,River Tame

,Ashton - under - Lyme .

P . n odosocarin atus F . Romer . Ran ge, Dibun ophy llum zon e toMillston e Grit .

SYN . Nauti lus n odiferus Armstron g , Tran s Ge o l . Soc . Glasgow, vo l . i i ,

p t . i , p . 74 p l i , figs . 6—7 .

P leuron auti lus n odosocarin atus Fo ord, GEOL . MAG . , 189 1 , p . 481 ,with wo odcut .

Marin e Band,Caton Green

,Lan cashire ; below Little Limeston e,

Smith’s Grit, n ear Hawes, Swaledale, Yo rkshire . U. Castlecary , Arden ,

Barrhead, Garn gad Road,

Gare,Westerhouse

East Kilbride, Sco tland .

P . scarletten sis Reidr—Top of Upper Dibun ophy llum zon e or

base o f Pen dleside Series Scarlet Quarry , Isle o f Man .

EPHIPPIOCERAS Hyatt .Typ e

— E . ferratus Cox ,Co al - measures, Ken tucky , U.S.A .

Ep hipp ioceras bi lobatumSow .

—Upper beds o f Carbon iferous Limeston e to Coal - measures . The Cayton gill Beds ,

o f Sawle‘y ,n ear Rip o n ,

Yo rkshire ; 4 LawsLimeston e, Combe , Northumberlan d ; below the3rd Grit, Con gleton Edge , Cheshire Castletown Limeston es, Isle o fMan . Carbon iferous Limeston e , Clo seburn ,

Dumfriesshire , Sco tlan d .

E . clitellarium J . de C. Sowerby .

—Coal—measures . Pen n yston eBed

, Shropshire Marin e ban d above the Barn sley Coal , Yorkshire .E . costatum Fo ord .

— Coal—measures . Pen n yston e Bed, Shropshire ; below the Gin Min e Coal, N. Staffs ; Leicestershire .E . wi ldi Hind .

— Coal - measures . Above the Bullion Coal , Carreheys (n ear Co ln e) , Burn ley , Shere (n ear Littleborough) , and Sho lver(n ear Oldham) , Lan cashire .

408 Dr . Wheelton Hi n d

STROBOCERAs Hyatt .Typ e

—S . harti i Dawson ,Acad . Geo l . , 3rd cd . , p . 311, fig . 125 .

Stroboceras sulcatum J . de C. SOW .

—Upp er Dibun Ophyllum zon eo f Carbon iferous Limeston e to Millston e Grit . 4 Laws Limeston e

,

Combe,an d Redesdale Iron ston e ,Northumberlan d Millston e Grit,

Cleul Quarries, an d Pen dleside Series, Burn sall, Yorkshire ; D2 ,

River Ribble, an d Sabden ShalesL Rough Le e , Lan cashire ; n earKirkby Lon sdale, Westmorland ; Castleton ,

Bradbourn e, and

Chrome Hill,Derbyshire ; Po o lvash, Isle o f Man . In Scotland

specimen s are mixed with S . quadratus' Flem . , which is regarded as

a syn on ym . Little Island,co . Cork ; Mullaghfarry and Cross

p atrick, Killala, co . Mayo ; Carn teel, co . Tyron e , Irelan d . Vise,Belgium .

S . crassumFo ord— Rin g n earEn n iskillen ,co . Ferman agh, Irelan d .

S . bisulcatus de Kon in ck .

— Upp er Dibun ophy llum zon e . Swin donQuarry , n ear Craco e, Yorkshire Parwi ch , Irey Cliff, and Castleton ,

Derbyshire . Visé,Belgium .

S . quadratus Flemin g .

— Coal - measures ;Pen dleside Series ;Sco tlan d. Coal - measures of Shropshire (Pen n yston e Beds) Lowickan d Redesdale Iron ston e, Northumberlan d .

‘

Roscobie,Fife, an d

in n eighbourho od o f Glasgow, Sco tlan d . Foyn es Islan d, Irelan d .

DISCITOCERAS Hyatt .Typ e .

—D . costellatum M‘

Coy .

Discitoceras levei lleanum de Kon in ck .

— Castleton , Derbyshire ;Scarlet Quarry , Isle o fMan . Clan e an d Naas

,co . Kildare

,Irelan d .

D. discors M‘

Coy .

— Askeaton ,co . Limerick .

D . wrighti i Fo ord — Upper Dibun ophyllum horizon . Po o lvash,

Isle o f Man . Little Islan d an d Middleton,co . Cork, and Askeaton ,

co . Limerick,Ireland .

D . costellatumM‘

Coy .

—Milicen t an d Clan e,co . Kildare

,Ireland .

PHACOCERAS Hyatt .Typ e

— P . oxystomum Phil lips .

Phacoceras oxystomum Phillips:— Probably base o f Pendleside

Limeston e . Hodder Place,Lan cashire ; Lowick

Northumberland ; Po o lvash,Isle of Man . Floren ce Court, En n is

killen (Phil lips), and Drumscraw,Tyron e Irelan d . Visé

,

Belgium .

P . rectisuturale Foord— CO . Kildare .APHELECERAS.

Typ e— A . mutabi le de Kon in ck .

Ap heleceras mutabi le M‘

Coy .

— Upper Can in ia zon e . Kn iveton ,

Derbyshire . Rathfarn ham,co . Dublin ,

Clan e andNaas, co . Kildare ,Rathkeale, co . Limerick

, Little Islan d, co . Cork, an d Cregg, co .

Meath,Irelan d. An seremme

,Belgium .

A . hibern icum Fo ord Crick — St. Doo laghs, co . Dublin , Ireland .

A . trochlea M‘

Coy .

— Probably C o r S horizon . Ken dal . Co okstown

,co . Tyron e , Irelan d .

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4 10 Dr . Wheelton Hi n cl— Br i tish Carbon iferous Nauti lo i ds .

PLANETOCERAS Hyatt .Plan etoceras g lobatum J . de C. Sow — Horizo n C . St . Do o laghs,

co . Dublin,Kildare

,an d Do n era'ile

,co . Cork

,Ireland . A very

much misun dersto od fo ssil ; few authors have co rrectly referredsp ecimen s to this genus .

COLo cERAs Hyatt .Co loceras coyanum d

’

orbign y .

— C.

- S. horizo n . Kilmallo ck and

Rathkeale, co . Limerick,an d Ballydufl ,

co . Waterford,Ireland .

De Ko n in ck quo tes the species from Visé,Belgi

C. bistriale Phillips — Po o lvash,Isle o f Man . Clan e

,co . Kildare ,

an d Tourde ely ,co . Limerick

,Irelan d . Woodmil l , Dun fermlin e ,

Sco tlan d . The distribution Of this sp ecies requires furtherexamin ation

,and the Irish examp les are from Lower Carbon iferous

beds and the British from higher on ly .

THRINOOCERAS Hyatt .Thrin coceras hyatti Fo ord — St . Do o laghs, co . Dublin .

T . hibern icum Foord .

—Glen ban e , co . Limerick .

T . luidii Martin .

-Narrowdale,Staffs ; an d the Lime sto n es o f

Pen dleside horizon, Lo n gston e , Derbyshire ; Hodder, Lan cashire ;

Elbo lton,Yorkshire . Lady McLaren

’

s Quarry ,n ear Prestatyn ,

Wales .

AIPOOERAs Hyatt .Aip oceras comp ressum Fo ord — Ho rizon C. Clan e , co . Kildare ,Irelan d .

ASYMPTOCERAS Ryckho lt, 1852, emend . Hyatt, 1883—93.

Asymp toceras crassilabrum Fo ord .

— Clan e,co . Kildare .

A . foordi Hyatt — Clam ,co . Kildare, and Rathkeale , co . Limerick .

SOLENOOHEILUS Meek Worthen ,emend . Hyatt, 1883—93.

So len ochei l‘

us Phillips .

— C.

- S. Salt Hill an d,Bellman Quarries,

Clithero e,Lan cashire . St . Do o laghs, co . Dublin , Clan e , co . Ki ldare ,

Rathkeale an d n ear Askeato n ,co . Limerick . Black Rock and Little

Islan d,co . Cork, fide Griffiths .

S . hibern icus Fo ord .

SYN . Acan thon auti lus bisp in osus Fo ord .

Clan e , -co . Kildare, and Little Islan d, co . Cork .

S . clausus Fo ord— Little Island, n ear Cork probably D .

S . caledon icus Fo o rd — Elbo lton ,Yo rkshire . Arden Quarry ,

Nitshill; Glasgow,and Roscobie , Fife, Sco tlan d .

S . cyclostomas Phillips — Millston e Grit, Horsebridge Clough, andHigh Green Wo od at the horizon of the Sabden Shales Crowdeco te ,Derbyshire . Axto n ,

N. Wales .

S . crassiuen ter de Ko n in ck .

—The Little Limeston e, Weardale ;(var. ) Castleton ,

Derbyshire .

H . A . Baker— Loose Aren aceou s Sedimen ts . 41 1

S . infundibulum de Ko n in ck .

— Upp er Beds o f Dibun ophy llum

zon e at Elbo lton,Yo rkshire Ho llin gton En d, Derbyshire .

S . ingen s Martin — Upper beds o f the Dibun ophy llum zon e .SYN . So len ochei lus p en tagon alis Phil l ip s .

{Little Limeston e, Weardale, Durham ; Bradbourn e an d n earAshfo rd,Derbyshire ; Astbury Old Quarry , Cheshire . Bathgate ,Lin lithgowshire, Clo seburn an d Kirtlebridge , Dumfriesshire , an d

Arden Quarry , Nitshill, Scotlan d .

S . derbien sis Fo o rd—Upp er Dibun ophyl lum zon e . Park Hill,

Castleton,an d Crowdecote

,Derbyshire ; Narrowdale , Staffs ; 4Laws

Limeston e,Combe, Northumberlan d ; Po o lvash,

Isle of Man . I don ot con sider the variety n amed S . derbien sis var . globularis o f

Fo ord sufficien tly distin ct to be retain ed .

S . g lobosus Hind—Millston e Grit, Lower Coal - measures . Caton ;Sales Wheel

,River Ribble ; Bullion Coal, Carreheys, n ear Co ln e ,

Burn ley Coalfield, Lan cashire ; the marin e bed, Silica Quarrv

Con gleton Edge, Cheshire .CYCLONAUTILUs Hin d

Cyclon auti lus umbi licatus Hind .

—Coal - measures . Ro o f o f the

Bullio n Coal,Burn ley .

O n the In ve stigatio n o f the Me chan ical‘

Co n stitutio no f Lo o se Are n ace o us Se dim e n ts by the me tho d o f

Elutriatio n , W ith t sp e cial re fe re n ce to the Than e tBeds o f the So uthe rn Side o f the Lo n do n Basin .

By HERBERT ARTHUR BAKER,M.Sc .

,F.G.S.

(Con tin ued from p .

LEADING CHARACTERISTICS OF ELUTRIATION - CURVES o r SEDIMENTS .

ITH regard to the laws govern in g the tran sport, sortin g , anddeposition o f sedimen ts

, much has still to be learn ed, but o n e

fact emerges clearly from themass of presen t data . Durin g the pro cesso f tran sp ort by water the lo ad undergo es selective treatmen t, o r

,

in o ther wo rds, is sorted . The late Dr . G. K . Gilbert,in the course

o f his imp ortan t work o n the tran sportation of débris by run n in gwater 1 carried out exp erimen ts with mixtures o f several grades o f

detrital material and found that before the slop e of the stream hadbeen defin itely established (i . e . before the attainmen t o f un iformityo f con dition s) , an d especially when low velo cities were used, thecurren t tended to sort the debris

,buildin g deposits with the coarser

part and con tinuin g to tran sp o rt the fin er material . This “

fact hasa sp ecial bearin g on the study of n atural sedimen ts . The state - Oi

e quilibrium, or of p erfect un iformity o f con dition s, is seldom,if ever,

comp letely realized in n ature,an d even when approximately reached

is n ot,as a rule, Of lo n g duration . Further, in gen eral, the de trital

1 G ilbert, The Transp ortatio n o f Débris by Run n in g Water U . S . Ge o l .

Surv. Pro fe ssion al Pap er 86 , 19 14 .

4 1 2 H . .A . Baker— Loose A renaceous Sedimen ts .

dep o sits of the geo lo gical co lumn are the results o f tran sp ort by an d

dep ositio n from comparatively Slow - movin g curren ts . Dep o sitso f torren tial character are excep tion al . Consequen tly ,

we shouldexpect to fin d far - travelled n atural sedimen ts, which have beensubj ected to lon g—co n tinued aqueous action before dep o sitio n ,

showin g in a marked degree the results o f selective treatmen t,

an d sedimen ts dep o sited after a sho rt career under tran sp ort showin gvery little eviden ce o f sortin g . The material compo sin g aren aceoussedimen ts dep o sited un der marin e con ditio n s must, ’ in gen eral,have had an earlier history , durin g which it formed part o f fluviatileo r estuarin e dep o sits, an d in view o f the greater vicissitudesexp erien ced should show the results o f selective action in a highdegree . On the o ther han d,

a dep o sit such as a fluviatile loam or

brickearth,dep o sited after o n ly a short career un der tran sport,

an d n ot havin g been subj ected to an y sp ecial typ e of selectiveaction

,should show a marked absen ce of sortin g . The exp ectation

is verified . Fig . 3 shows,for purpo ses o f comparison ,

the typ icale lutrl ation - curves y ielded by fiuviatile , estuarin e, an d marin esedimen ts . In the case o f the fluviatile deposit, its immaturity ,

from the p o in t _

of view of its modification un der aqueous action,is

shown by the curve by the marked absen ce'

o f a hump an d bythe very low gradin g factor . The marin e sedimen t y ields a curvewith a p ronoun ced hump an d gives a much higher gradin gfacto r . The estuarin e sedimen t is o f in termediate typ e . Man y moreexamp lesmight be given to shew, the soundn ess o f this gen eralizatio n ,

but they are scarcely n ecessary at this p o in t .

MECHANICAL CONSTITUTION OF THE THANET BEDS OE THE SOUTHERNSIDE OF THE LONDON BASIN

“

The fo llowin g summary of the leadin g features o f the mechan icalco n stitution exhibited by the Than et Beds is based up o n the resultsof a very large n umber of an alyses of samp les from a widespread area .

Everywhere alon g the southern side o f the Lon do n Basin theThan et Beds are always pro gressively coarser from the base upwards .

A samp le from the upp er part of the Than et Beds in an y lo calitywill alway s y ield a higher Equivalen t Grade factor than will an o thertaken from a lower level . Samp les taken from Similar horizo n s indifferen t lo calities "

do n ot, however (un less the lo calities are on ly a

mile o r two apart) , y ield corresp o n din g figures . The Than et Bedsbecome fin er in grain as we pro ceed bo th eastward an d. westwardfrom the ty p e district o f West Ken t . The Than et Beds of EastKen t

,as shown by the sectio n s at Pegwell Bay an d Hern e

'

Bay ,

are the mo st fin e -

grain ed represen tatives of these dep osits in thesouthern p art o f the Lo n do n Basin (se e Fig . It 'is on ly , however,in the upp er part o f the beds that

“ the tran sitio n from coarser tofin er material

,eastward an d westward o f West Ken t, is steadily

p ro gress1ve .,The

,lower part Shows greater variation . The lower

p o rtion o f the beds in theWest Ken t type '

area Shows fin er sedimen t-s

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H . A . Baker— Loose Ar en aceous Sedimen ts .

than those at corresp on din g horizon s an ywhere to the west and 'for

man y miles eastward . The Lower Than et Beds of East Ken t,

are,

however,

fin er than the fin est sedimen ts o f the West Ken t sequen ce .Some o f the very fin e , in durated, muddy sedimen ts o f Pegwell Bayproved so refracto ry in the laboratory that n o mechan ical an alysiswas p ossible . The West Ken t typ e o f Than et Beds Shows thegreatest amoun t o f variatio n in mechan ical con stitution seen inthese beds

.

anywhere In the Lon don Basin ,the Equivalen t Grade

factor ran g i n g from 059 mm . at the base o f the depo sit to 146 mm .

at the top . The eviden ce suggests that early in Than etian timessp ecial co ndition s o btain ed In the West Ken t area

,whereby loamy

and silty beds, n ot p ossessin g in an y marked degree the

fl ow

A N D S A N D

0 O A 12 5 ?

C L A Y

M

FIG . 4 .—Diagram Showin g thickn e ss of Than et Beds an d ran ge in mechan ical

con stitution ,fo r various l ocal itie s , from we st to e ast, alon g the southern

side o f the Lon do n Basin .

characteristics of marin e sedimen ts, were bein g dep osited lo cally ,somewhat before the defin ite establishmen t of typical marin eco n dition s . From the fact that the lower Than et Beds eastwardan d westward of West Ken t (excludin g the East Ken t area) arefairly well—Sorted sedimen ts, givi n g elutriation - curves o f marin etyp e, on e is temp ted to hazard the con j ecture that the lowest bedsin West Ken t may be o lder than these .Thickn ess of deposit, together with n arrow ran ge o f variation in

mechan ical con stitution, may be taken to in dicate approximate

un iformity of con dition s of sedimentation , an d comparative paucityo f sedimen t with con siderable litho logical variatio n , the reverse .

H . A . Baker— Loose A r en aceous Sedimen ts . 4 1 5

Fig . 4 in dicates the comparative in stability of con dition s o f sedimen tation in West Ken t durin g the dep o sition o f the Than et Beds .

The diagram (Fig . 5) Shows the rough , provision al classificatio n o f

aren aceous sedimen ts based up on values of Equivalen t Grade andGradin g Factor, in

'

use by the writer . The value o f the Equivalen tGrade facto r decides whether a sedimen t shall be classified as a

san d,a silt

,or a clay ,

the limit between san ds and silts bein g takenat

'

08 mm .,an d that between silts an d clays at '

02 mm . The valueo f the Gradin g Factor decides whether a sedimen t shall be classifiedas a true san d or Silt, or as a loam

,sin ce the characteristic of the

loams is the lowvalue o f the Gradin g Factor . The limitin g valueo f the Gradin g Factor which separates san ds an d silts on the o n ehand from loams o n the o ther

,is taken at

'

6 . The classificationeems to an swer very well .

F'

l N E

S A N D ‘

F l N E F l N E

S I L T Y S A KI D Y

L O A N L O A N

FIG . 5 .

— Provision al classification o f the fin er aren ace ous sedimen ts , based on

Equivalen t Grade an d Gradin g Factor value s .

Fig . 6 shows typ es of elutriation—curves y ielded by the Than etBeds o f various localities alon g the southern side o f the Lon donBasin , an d the table at the end o f the paper gives a selection from a

large number of mechan ical an alyses obtain ed by the writer .

The con struction o f a graph Showin g the relatio n between theGradin g Factor an d Equivalen t Grade y ields results of remarkablein terest in the case of the Than et Beds . When a series of fieldsamp les are taken from successive levels in the Than et Beds at an yon e lo cality an dm echan ical an alyses are carried out an d the relatedvalues of Gradin g Facto r an d Equivalen t Grade are p lo tted on

a graph , it is foun d that the p o in ts obtain ed show a stron g tenden cyto lie on a straight lin e . What is even more remarkable

,however,

4 1 6 H. A . Booker— Loose A ren aceous Sedimen ts .

F'

IG'

. 6 .

— Elutriation curve s (much reduced) o f Than et Beds ofSouthern Side o f

Lon don Basin .

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H . A . Baker— Loose Ar en aceou s Sedimen ts

TABLE OF MECHANICAL ANALYSES OF THAN

LOCALITY, ETC .

Fl n e Sl l t. C

- 01mm

Beddin g ton , Surrey . Clack Son s’

p i t. Upp er part o f

Than e t San dBeddin g ton , Surrey . Clack Sons’ p it. Lower part o f

Than et San dCharl tOn . Gilbert

’

S p it. Uppe r Than et SandCharlton . Gi lbert

’s p it. Lower Than etBeds (Blackfo ot) .

Plum stead Statio n . Upp er part of Than et San dPlumstead . Proctor

’s p it, e ast o f Plumstead Common .

Upper part o f Than et San d 103 0East Wickham . Tuff Hoar

’

s p it. Than et San d ,

upper part 8 - 48

East Wickham . Tufi Hoar’s p it. Than et San d ,

m iddle part 1 1 0 54 52 - 68

East Wickham . Tuff Hoar’s p it. Than et Beds ,

l ower part 26 2 0 70 - 90

East Wickham . Wickham Lan e Brickfie ld . Than etSan d , about 15 fe e tbe low jun ction withWo o lwichBeds 59 - 66

The Cave s East Wickham Val ley . Lower Than etBeds , about 10 fe e t above Bul lhead Bed 75 - 54

The Cave s”

,East Wickham Val ley . Lower Than et

Beds , immediate ly above Bul lhead Bed 13 - 1 2 14 - 20 62 1 6

Abbey Wood . Roadside section , Kn e e Hil l . Upp erThan et San d , immediate ly be lowWo o lwich Beds 12 10

Abbe y Wo od. Co op erative So ciety’s E state . Than et

Beds , about 15 fe et above base 18 0 2 41 72 24

Old Bexley Sprin g Place , Dartford Lan e . Roadside

section i n Upp e r Than e t San dErith . Norris

’S p it. Lowe r part of Than etBeds 14 - 36

Joyde n’

s Wo od ,n ear No rth Cray . Than e t San d , about

m iddle o f dep o sit

Farn in ghamWoods , Southern part. Than et San d , fairlyh igh up i n dep o sit

Swan ley . Railway cuttin g betwe en Swanl ey Jun ction an d

Farn in gham Road Station . Than e t San d, upp er part. 32 85

Swan l ey . Railway cuttin g betwe en Swan l ey Jun ctio n an d

Farn in gham Road Station . Than et Beds , l ower part 76 77

- Sto n e . Ston e Court, No . 3 p it, we st o f Cotto n Lan e .

Lowe r part of Than et Beds , a few fee t above Chalk 10 - 27 12 - 1 2 72 - 10

Daren thWo ods . Fox an dHoun dsLan e . Lower Than etBeds , just above Chalk 20 - 02 1 1 - 20 44 - 25

Hulbury , Lul l in gston e . Le e’s p it. Than et Beds , l ower

part

Be an . Moun ts Wo od den eho l e . Than e t San d .

’

upp e r

part

Re culver . Cl iff section . Than et Beds , uppe r partPe gwe l l Bay . Cl iff section . Ye l low l oam ,

in durated .

Highe st Than e t Beds se en , but stil l in lower part o f

deposit 59 00 28 35

Pe gwe l l Bay . Cl iff section . Than e t Beds , lowe st part,just above Chalk 64 62 22 - 87

H . A . Baker— l oose A r en aceous Sedimen ts.

SAND GRADES .

- 125mm .

- 15 mm . < ° 2mm .

- 2mm .

35 - 47 1 2 36

20 - 12

58 - 50

15 - 00

50 - 26

39 - 67

1 1 - 77

744

781

834' 581

835

800

834

° 751

- 761

- 758

' 592

° 788

- 736

829

748

0 838

- 823

- se4

- 746

- 669

798

656

558

- 555

REMARKS .

Buff san d .

Fin e y e l lowish - buff san d .

Pale san d .

Grey ish - buff coarse silty lPale -

y e l low san d .

Pale - buff san d .

Pale - buff san d.

Fin e , pale - co loured san d .

Grey ish - bufi‘ coarse Silt.

Fin e , pal e - buff san d.

Pale - buff coarse silt.

Pale - buff coarse silty loa

Pale - buff san d .

Buff coarse silt.

Pale - bufi san d .

Grey ish - buff coarse s ilt.

Fin e y e l lowish - buff san d .

Fin e y e l l owish - buff sand .

Pale - buff san d .

Pale - co loured coarse sil t.

Grey ish - bufi coarse silt.

Grey ish - buff coarse si lty ll

Fin e y e l lowish - buff sand .

Fin e greyish - brown san d .

Very fin e y e l lowish - buff S

Ye l low, calcare ous , mediu

Pale y e l l owish -

grey fin e sil

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4 20 H. A . Baker— Loose Aren acebus Sedimen ts .

This remarkable feature in the Than et Beds,although apparen tly

un iversal "

in Ken t,app ears to be wan tin g farther west, in Surrey

From an examin atio n o f samp les in that area the writer n o ted thatin the upp er part o f the Than et Sand an in crease in the Equivalen tGrade value Was accompan ied by a dimin utio n in the Gradin gFactor . This feature was traced as far east as Charlton ,

where thewriter foun d that the extreme top o f the

_Than et San d,whilst givin g

the highest Equivalen t Grade value o f an y Than et Sand an alysed,

gave a somewhat lower Gradin g Factor than was expected . Itseems likely that the readjustmen t of co n dition s which resulted in

“

the succeedin g Wo o lwich an d Readin g Beds bein g of marin e typ ein East Ken t, and o f estuarin e an d freshwater typ e farther west,commen ced before the dep o sition of' the Than et Beds had beencompleted .

(To be con tin ued . )

REVIEWS.

WILLIAM SMITH HISMAPs AND MEMOIRS . By THOMAS SHEPPARD,

M.Se . , F .G.S , Curator o f the Hull Museum . pp . 75—253 (theorigin al pagin ation is retain ed) , with 48 p lates an d o therillustration s . Hull : A . Brown Son s . 1920 .

IN these days of specialization the study o f the history of therise and progress of our scien ce receives less atten tio n than in

earlier times . In the writer’s youth, for in stan ce , a histo ricalquestion on each of the v subjects for the Natural Scien ces Tripo s

‘

at

Cambridge was compulsory , but this has lon g ceased to be the case .This is a pity , for apart from sen timen tal con sideration s, the studen twi ll reap much advan tage from a study o f the di fficulties with -whichhis predecessors were con fro n ted

, an d of' the mistakes which they

made . On e of the troubles of a geo logistwho has to work in a coun tryof which the geo logy is un kn own is due to the fact that his fie ldwork at home is learn t in an area which has been mapped - in detail .By study in g the life an d wo rk of Smith

,he will discover how the

work was don e in En glan d at a time when its geo logy was practicallyun kn own .

The imp ortance of William Smith ’s work is n ow un ive rsallyrecogn ized, but it was n ot always so . In Dr . Brewster’s Edin burghJournal of Scien ce for April , 1831 , un just cen sure was passed uponthe Geo logical Society o f Lon don for awarding the first Wol lastonMedal to Smith . The action of the So ciety ,

however,was fully

justified by a writer F .

”

in the first number o f the Mon thlyAmerican Journ al of Geo logy , published in July ,

1831,who passes

high en comium upon Smithfs work .

Buta lthough the importan ce of the work is so gen erally recogn ized,we have up to n ow n ot been in p o ssession of a very full an d detailedaccoun t of it . Professor J . Phillips

’

s Memoirs of Wi lliam Smith,LL .D. ,

app eared in 1844, but the ,bo ok is n ow very scarce . In 1897

the late Professor Judd co n tributed an importan t pap er to theGEOLOGICAL MAGAZINE on William Smith ’s Man uscript Map s ”

Much scattered in formation about Smith is in corpo ratedMr. Sheppard’

s work, and n o ted in the bibliography at the en d o f

the bo ok . But a detailed accoun t o f the labours o f the Fathero f En glish Geo logy did n o t exist . Now

,thanks to 'Mr . Sheppard,

an d to the wise p o licy o f the Yorkshire Geo logical So ciety , fromwhose Pro ceedin gs the memo ir is reprin ted, we have it .It Is in deed fortun ate that Mr . Sheppard un derto ok the task o f

writin g the work . A skilled geo logist, he 1s also fully versed In thescien tific methods o f the histo rian an d bibliographer, an d has

eviden tly left n o ston e unturn ed in his efforts to trace Smith ’svarious publication s an d manuscrip t writin gs, with the result thatwe have a worthy and almo st exhaustive record of Smith’s con

tribution s to scien ce .

422 Revi ews Wi l liam Sm i th : Hi s Map s an d Memo i r s.

After a few in troductory pages the author gives some n o tes onwork con n ected with geo logical mappin g an d determin ation o f the

sequen ce of strata prior to Smith’

s time . Sp ecial n otice is taken o f

the establishmen t o f a sequen ce o f strata from the Chalk to theCoal - measures by the Rev . John Michell , who se claims as a geo logi calinvestigator have recen tly been presen ted by Sir Archibald Geikiein a Memoir of John Miche ll published by the Cambridge Un iversityPress in 1918 . Stress is also - laid upon the imp ortan ce of the serieso f Coun ty Surveys published by the Board of Agriculture in 1794an d the succeedin g y ears, man y o f which indi cate by co lour then ature o f the so ils . As Mr . Sheppard remarks, there is n o doubtthey were of l guidan ce to Smith in h is wo rk .

”

The greater part of the bo ok (pp . 103—80) is occup ied with an

accoun t o f Smith’s various publicatio n s —map s, section s, _

books ,an d papers

,in chron o logical order. This is o f the highest value ,

and eviden tly en tailed an en ormous amoun t o f research . It isadmirably illustrated by reproduction s o f maps, section s, titlepages o f books, tables of strata, an d o ther material .The fullest details are n aturally reserved for those works and

p ortion s of works which deal wi th Yorkshire , but an y on e whowishes to obtain an accoun t o f Smith’s work will do so . Man y o f

the items refer to previ ously un kn own or forgo tten publication sbrought to light by the author after exhaustive inquiries . Theco n cludin g parts of the bo ok treat o f Smith’s MSS.

,n otices of his

wo rk by o ther writers,apart from tho se which have been previously

published,memo rials to Smith,with {illustration s o f busts ,

'p ortraits ,dwellin g -

p laces, and mon umen ts,also some app en dices an d a

bibliography .

A few triflin g misprin ts o ccur, but '

there is a discrepan cy betweenthe description of the p late facin g p . 107, The origi nal Table o fStrata n ear Bath, dictated by W. Smith , an d written by the

Revr Joseph Town send,in 1799 , and the in scription o n the table

by Smith o n p . 108,This Table o f Strata, dictated by myself, is

in the handwritin g of the Rev . Ben . Richardson ,an d was first

reduced to wri tin g at the house o f the Rev . Jo seph Town sen d,

Pulten ey St . ,Bath

,1799 . William Smith .

” On p . 134 the author,referrin g to a copy o f Strata iden tified by Organ ized Fossils,states that in the copy in the po ssessio n of the Geo logical Societyo f London the covers are fortun ately preserved, but that the dateo f part iii“ is torn o ff. The writer o f this n o tice has a copy with thecovers in tact

,and the date of part iii is

,as given by the author,

“September 1Mr. Sheppard must be heartily con gratulated up on the app earan ce

o f this mo st imp ortan t work, an d than ks tendered to the Fellows o fthe Yorkshire Geo logical So ciety . Every geo logist should read thebo ok, an d n o studen t of the history o f geo logical discovery ,

or

co llection of wo rks bearin g thereon ,can afford to be without it .

We learn from the preface to Mr . Sheppard’

s wo rk that more

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4 24 Revi ews— Geo logy of the Coun try aroun d Li chfie ld .

p re- Carbon iferous rocks an d the productive Coal - measures is revised

an d brought up to date with modern mi n in g in formation ;in terestin gaccoun ts are given Of the structural features, particularly o f theboun dary faults, and the modern subdivision s o f the red rocks o f

the Upp er Coal - measures are described in very con siderable detail .With regard to the productive Coal - measures, an in terestin g fact isthat in the NorthWarwickshire field the lower coals have been foun dto improve towards the n orth , an d that there is n ow talk of reopen in go ld p its which were o rigin ally on ly sun k to the seven - feet co al higherin the series an d sin kin g them to these lower coals . With regardto the Up perCoal - measures, a satisfactory subdivision comparablewith that well kn own in No rth Staffo rdshire has n ow been establishedfor this area .

’ The Black—ban d Iron ston e Group is absen t, but theEtruria Marls, with their characteristic Esp ley ro cks, are of n ormaltyp e . The succeedin g Halesowen San dston e comprises two sub

division s, a lower series o f sandsto n es an d an upp er on e o f marls

with Sp irorbis limeston es ; o n e o f_

these,the In dex Limeston e ” ,

at the base of the marls,an d restin g o n a wellmarked san dston e, is

o f great value In mapp in g an d determin in g the depths o f the coals .

The Keele Beds are the n ormal red marls With Sp irorbis limestones ,but are overlaid by 2,000 feet of red san dston es, the HamsteadBeds,which seem to be definitely pre - Permian

,an d are therefore in cluded

in the Coal measures . The accurate recogn ition of horizon s In thesero cks is a question of great imp ortan ce , sin ce the possibility or

o therwise o f the presen ce o f coal at workable dep ths may dep en den tirely on the correctn ess of the diagn o sis . AS an instan ce of this,the coun try between Tamwo rth an d the Western Boundary Faulto f the North Warwickshire Coalfield may be quo ted . Here ro ckswhich were origin ally mapp ed out as Keup er San dston e have n owbeen proved, by the recogn ition o f Sp ir

'

orbis limeston es associatedwith the ‘

p eculiar rock - typ e kn own as Pellet San dston e, to belon gto the Keele series . This determin ation allows a fairly defin ite ideato be formed about the dep th o f the coal, whereas, on the formermappin g , n o estimate could have been g iven owin g to the greatun con formi ty existin g between the Coal - measures an d the Trias .

Both the coalfie lds described are bounded on bo th sides by faultso f con siderable down throw. These faults Show man y po in ts o f

in terest,an d n ot the least o f these IS the great width of the disturbed

areas,which has been p roved by the drivin g o f exploratory headin gs .

On e'

of these headin gs, driven through the Eastern Boundary “ Faulto f the South Staffo rdshire Coalfield

,from the Walsall Wood

Co llie '

ry’

s workin gs, proved the disturbed area to be 350 yards wide ,while further south at Aldridge the belt of disturban ce is yards

wide .“ In the first of these exp loration s the headin g left the ShallowCoal and was driven for 75 yards through measures with brokenmasses of coal, for the n ext 73yards it passed through grey measuresmuch squeezed and compressed,

dipp in g 24 de'grees from

a distan ce of 148 yards to 350 yards from the startin g - po in t the ro ck

Revi ews— Mesozo ic Igneous Ro cks . 425

was all red an d mo ttled marls , faulted an d broken for the first100 yards, an d over the second 100 yards dipp in g more regularlyat about 26 degrees . At 350 yards the headin g passed throughan o ther fault, an d beyond this in to red marl correlated with theKeele Beds an d havin g a still gen tler dip o f 16 degrees .

This an d the eviden ce from“ the o ther boun dary faults Shows thatthey ,like man y o ther imp o rtan t lin es o f dislocation ,

are areas“

o f

wide shatterin g and step faultin g , partakin g more o f the n ature o fbroken fo lds than of clean fractures, a phen omen on which is wellseen in some o ther coalfie lds .

An o ther po in t o f in terest about these faults is their throw in p o stTriassic time

,which is large in comparison with that observed else

where . This post - Triassic throw common ly amoun ts to 200 to 400feet

,while In two cases it exceeds 700 feet . The p ossibility of the

existen ce of workable coal between the two coalfie lds i s reviewed,

but here the grounds on which the estimates can be made are faifrom secure . The un con formable relatio n s between the Trias an d

the Coal - measures, the difficulty o f determin in g the p ost - Triassicthrow of faults, an d in the southern p ortio n the possibility Of uprisin go f the p re - Carbon iferous

‘

fio or, al l ten d to render the formation o f

defin ite opin io n s a very difficult task . The on e fact which stan ds out’

app ears to be that the coal over a large part o f this co n cealed co alfield must be deep

, in p laces as much as feet . The mo stp romisin g areas app ear to be In the n orthern part, where the KeeleBeds are absen t, though here sin kin gs would have to pass through theheavily watered Bun ter . The surface o f the area is i n man y p lacesthickly covered with drift which must have ren dered surfacemapp in gvery difficult, Sin ce in man y places temp orary exp o sures laid barein diggin g for Sewers and foun dation s are all which’ can be obtain ed .

The o fficers o f the Geo logical Survey have, however, been veryfortun ate in the co - op eration o f the co lliery man agers, an d thestructure of the coalfie lds seems n ow to be established on a verysatisfactory basis . The map accompan y in g the memo ir is n ot y et

published owin g to causes co n n ected with the War .

A CONTRIBUTION TO THE KNOWLEDGE OF THE MESOZOIO IGNEOUSROCKS DEVELOPED AROUND THE TSUSHIMA BASIN ,

JAPAN . ByTAKEO KATO . Journ x Geo l . Soc . Tokio , vo l . xxvii , No s . 316

an d 317, 1920 .

IN these two papers a description is given o f a series o f ign eousrocks of late Meso zo ic, probably Cretaceous, age , o ccurrin g in

the n eighbourho od o f the Straits of Tsushima . The series compri sesan extrusive phase o f an desites an d rhy o lites , more or less metamo rphosed pn eumato lytically by a gran itic i n trusion allied to themasan ite o fPro fessor Ko to ,

the who le bein g subsequen tlypen etratedby a series o f acid dykes similar to the gran ite . It therefore affordsan example o f a comp lete n ormal sequen ce of erup tivity

'

of Pacific

426 Revi ews—;The Nomen clature of Petr o logy .

typ e, comprisin g vo lcan ic,pluton ic

,and hypabyssal phases ,

o bviously derived from a common magmatic basin . The in trusives‘also give eviden ce of a certain amoun t o f magmatic differen tiatio nin the form o f leucocratic and melan ocratic facies, with aplites an dp egmatites .

THE NOMENCLATURE OF PETROLOGY . By ARTHUR HOLMES, D .Sc . ,

F.G.S. pp . 284 . London : T . Murby'

Co . 1920 .

Price 123. 6d . n et .

OME y ears ago the autho r began to comp ile a card- catalogueo f p etrographic terms for the use of studen ts at the Imperial

Co llege of Scien ce in view o f the usefuln ess o f this catalogue andin resp on se to man y suggestion s he has n ow developed and publishedit in a handy fo rm.

J

In the In troduction o f twe n ty—on e pages the subj ect o f petrographic n omen clature is discussed in gen eral terms, and with theauthor’s remarks as to its comp le xity an d the un n ecessarin ess o f

man y of the n ames emp loyed by various authors we are in heartyagreemen t . Some p etro logists really seem to have gon e o ut , of theirway to co in cumbersome an d jaw- breakin g n ames, almo st imp o ssibleto remember o r to spell

,an d con veyi n g n o thin g as to the actual

character of the rock . In view o f the Commi ttee o n Petro graphi cNomen clature n ow sittin g it would be un seemly to en ter in to a

gen eral discussion o f the prin cip les to be adop ted in the future , butthe author’s temp erate statemen t o f his views may be read withprofit by all p etro logists .

The greater part o f the bo ok n aturally con sists of a glo ssary or

diction ary of p etrographic terms, in cludin g structures and propertiesas

‘well as typ es, an d in cludi n g those referrin g to ign eous, sedimen tary ,

an d metamorphic ro cks .

’

Un der each headin g a brief defin ition isgiven ,

wi th in man y cases the n ame o f the in troducer of the wordand on e o r more referen ces to the literature . The list app ears to becomprehen sive an d well selected ; a few mo re explan atio n s mightwell have been given o f terms emp loyed in econ omic geo logy , as bymin ers, and in the records o f bores . Thus we fin d that mo st of theSco ttish terms are in cluded

,while their En glish equivalen ts app ear

to be omitted; We con fess that it is very difficult to give an y precisedefin ition o f man y o f these words, owin g to the vaguen ess o f theiruse ; they are ,

“ however, very puzzlin g to studen ts and might wellhave been in cluded with some sort o f exp lan ation , even if on ly a

statemen t that they can n o t be defin ed precisely ; In this co n n exionwe are p leased to n o te that the author invites suggestion s fromp etro logists as to terms to be in cluded in an other edition .

Some useful app en dices are added to the text, givin g glo ssaries o fthe more common an d imp ortan t Fren ch and German p etro lo gicalterms, lists of Latin and Greek words an d prefixes, an d tables o f

classification ,the latter bein g largely based on the so - called degree o f

saturation of the rock, as suggested by Shand . Although we have

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4 28 Revi ews—Geo logy of theMid - Co n ti n en ta l Oi lfields .

gravels, an d clay s overly in g it , and certain dep o sits o f the 100 fo o tterrace, with peat and o ther recen t formation s . Some o f these areo f eco n omic value for brick - clays, mouldin g and furn ace san ds

,

and o ther purp o ses .

THE GEOLOGY OF THE MID - CONTINENTAL OILFIELDS . By T . O .

BOSWORTH,D .Sc .

,M.A .

,F.G.S

, p p . xii + 314 .

New Yo rk TheMacmillan Compan y . 1920 .

DR . BOSWORTH has p rovided in this vo lume a mo st usefu l

additio n to o il - fie ld literature . It is in the main an ep itomeo f the vo lumin ous an d detailed wo rk which has been carried out

in this area by the Un ited States Geo lo gical Survey an d o th erWo rkers . It

'

is n o light task , even if o n e has access to th en umerous American publicatio n s , to abstract f rom them thesp ecific in formation required

,and it is this '

task which the authorhas taken in han d

,an d he has shown a wise discrimin atio n In

selectin g from the vast amoun t o f detail available the salien tp o in ts to fo rm a gen eral , y et in certain resp ects detailed, summaryo f the who le .The material Is o n the who le well arran ged,

though perhap s itmight be said to suffer from over classification . The bo ok isdivided in to parts ”

chap ters ’

an d sectio n s an d

esp ecially in the later p ortio n o f the bo ok there is aquite n eedlessmultiplicity o f chapters, while the headlin es throughout are ratherremin iscen t o f the American p ress .

The work 1s sup p lemen ted by a very full bibliography (chap .

an d n umerous referen ces throughout the text . Part ii i givesan accoun t o f the vigo rous deve lo pmen t o f the field which broughtit from its modest productio n prio r to 1903 to its presen t po sitio no f p roducin g n early o n e - third o f the wo rld’

s an n ual o il output ,an d is o f especial in terest at the p resen t time when so much isbein g written o n the wo rld ’

s supp ly o f o il an d Am-

erica’

s p re sen t

an d future p o sitio n .

The text throughout is well supp l emen ted with plan s , geo lo gicalsection s, tables , etc . ,

to gether with a n umber o f pho tographs .

The autho r first discusses the g en era l structure an d stratigrap hyo f the regio n ,

an d then g ives in p arts vi an d vii a mo re detailedaccoun t o f the l oCal characteristics o f the differen t fields . Parts ixan d x give an accoun t o f n atura l gas an d its re latio n to the distribution of o il , to getherwith an outlin e o f the methods employ edfo r the recovery “

o f gas gaso lin e a p ro cess rap idly in creasin gin eco n omic imp o rtan ce with the ever - in creasin g deman d fo r

light Sp irit . The subj ect o f helium is dealt with , a matter o f which ,owi n g to the activities o f the cen sor

,we heard little at the

time o f its discovery In commercial quan tities in 1 9 17, but o n e

which,had the supp lies o f gas been mid Europ ean in stead o f

mid - Co n tin en tal , would mo re than p robably have been broughtforcibly to our n o tice .

Corr esp on den ce— J . E . Marr — R . M. Brydo n e . 4 29

In p art x1i the “

autho r fin ishes with some .

gen eral co n “

e lusio n s but we rather disagree with him that some cOn

clusio n s Seem in evitab l e The vo lume is so essen tially a co llectio nan d statemen t o f facts that p art x ii might well have been‘

omitted without much lo ss, esp ecially as tho se who will usethe bo ok

_ p resumably have, o r should have,at least a gen eral

wl edge o f the theories o f the o rigin an d co n cen tratio n o i o il

an d gas . T -hat subj ect In itself IS SO exten sive an d imp o rtan t thatto skim lightly over it in a p age or two hardly strikes o n e as in

keep in g with the rest o f the vo lume . As is essen tial to a bo ok o fthis n ature it is well in dexed,

which adds materially to its va lueas a wo rk o f referen ce .

The publishers are to be co n gratulated on the prin tin g an d

gen eral sty le o f the bo ok , though here an d there excep ti on mightbe taken to the p ro of readin g ,

which has been by n o mean s p erfect .

CORRESPONDENCE.

s . B . J . SKERTCHLY’

S STONE IMPLEMENTS .

SIR,- I am an xious to trace the imp lemen ts obtain ed by the late

Mr . S. B . J . Skertchly from dep o sits o f the districts aroun d Bran donan dMilden hall

,which he claimed to be o f mid Glacial age .

I should be glad if an y o n e in p o ssess-ion o f an y o f these wouldkin dly in formme o f the fact

, givin g all details con cern in g the labels,an d if p ossible, outlin e—figure_

s o f the specimen s .

I trust that you will be able to help me by in sertin g this letter Inthe GEOLOGICAL MAGAZINE .

JOHN E . MARR .

SEDGWICK MUSEUM, CAMBRIDGE .

August 5 , 1 920 .

LINGULA IN THE CHALK

SIR,

—Mr . G. W. Butler will fin d published records, n ow o f somestan di n g ,

in Brydon e’

s Stratigrap hy and Faun a of the TrimminghamChalk (London :

”

Dulau CO . ,an d in Griffith 85 Brydon e ’s

Z on es of the Chalk in Han ts . (Lo n don : Dulau CO . ,At

Trimin gham it ’

has been found bo th in the white chalk an d in thegrey chalk .

R . M. BRYDONE .

27 MAYBURY MANSIONS,

MARYLEBONE STREET W . 1 .

Ju ly 24 , 1920 .

PHYSIOGRAPHIC RELATIONS OF LATERITE .

SIR,

- At the en d o f his article in the May n umber of the Magazin eMr . . F . Dixey gave a summary o f the con dition s affectin g lateritization in Sierra Leon e

,but did n ot in clude a physiographic factor

430 Corr esp on den ce W. M. Davi s .

which app ears to be o f prime impo rtan ce, n amely , a late stage ina cycle o f subaerial ero sion ,

when the slow removal o f rock wastefrOm a worn - down lan d Surface p ermi ts deep p en etration of

weatherin g with very slow movemen t of groun d- water, and thus

allows time for the various chemical reaction s up on which lateritization so largely dep en ds . The gen eral statemen t o f this asp ect o fthe problem is as fo llows .

Con ceive the chan ges suffered 'by a recen tly elevated region ;comp osed mo stly of such rocks as common ly underlie laterite .In the early or y outhful stages of the cycle of erosion thus in troduced

,n arrow valleys will be In cised by the main rivers ; the

steep valley sides Will exhibit bare ro ck o r will be thin ly covered withcoarse rock waste which creep s rap idly down the slop e to the riverbelow

,whil e the groun d- water p erco lates downward more rap idly

still . Laterite can n o t be formed un der such condi tion s . In a , latero rmature stage of the cycle,man y bran ch valleys will also be in cised,and all the valleys will be open ed to slop es of a moderate degree ;bo th '

stren gth and variety of relief will thus reach their greatestvalues . The valley sides will then be covered wi th a thicker cloako f fin er ro ck waste, but the down - slop e creep of the waste an d thedownward p erco lation o f the ground - waterwill still be comparativelyrapid ; little or n o laterite will be formed . In still later an d

'

muchlon ger- en durin g stages o f the cycle, the valleys havin g been alreadydeep en ed about as much as p o ssible , the in ter- valley hills will beslowly subdued to moderate o r small relief

,an d their slopes will be

reduced to gen tler and gen tler declivity . Thus a con dition is reachedin which the removal o f ro ck waste from the gen eral surface o fthe region an d the movemen t o f ground

- water are very muchslower than they were on the Side Slop es of the mature valleys .

Weatherin g Will n ow en ter to greater and greater depths, groundwater will lin ger in the deep so il

,an d chemical chan ges wi ll have

time for deliberate op eration . If n o upheaval of the region takesp lace , the subdued hills may even tually be worn down to the gen tleun dulation s o f a p en eplain ,

in the o ld age o f the cycle, an d on sucha surface the processes of lateritization fin d their optimum .

If upheaval takes p lace after the p en ep lan ation an d lateritization

o f a region ,the laterite will be quickly removed where n arrow

valley s are rapidly in cised in the early stages of the n ew cycle o ferosion ; but the laterite will remain o n the up lan d areas un til ,as maturity is approached and reached

,these areas '

are invadedand co n sumed by bran ch valleys . The occurren ce o f laterite indi fferen t parts of the world gives much support to this view of its

o n In .

The relation of lateritization to physiographic o ld age thus invo lvedis in directly imp lied in Mr . Dixey ’

8 statemen t that “ in the mo rehilly an d moun tain ous parts o f [Sierra Leon e] . laterite Is n otn early so well developed (p . It would be in terestin g to learnif the o ther areas, where the so lid ro cks have been lateritized to

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432 Corr esp on den ce— E. Hi l l .

the Rothstock Cirques, the Creux du Ven t (Jura) , with Gavarn i-ean d o ther cirques in the Pyren ees I may add that I saw in 1908from a steamer two rather

,Small but '

go od cirques o n the flan k o f

Salin a (highest p o in t feet) in the Lipari Islan ds . In thesean d o ther coun tries

,this question has been always in my mInd

,

s o that I can n o t recede from the po sition which I have assumed .

T . G. BONNEY .

THE CAUSES OF GLACIATION .

SIR,

— In Nature.of July 29 , 1920 , is an article by Dr . C. G. Abbo tt ,

o f the S mithson i an Astrophysical Observatory ,en titled So lar

Variation an d .the Weather In it he gives an accoun t o f observa

tion s o n so lar radiation . These showed o n their face a variabilityo ver an extreme ran ge o f 10 '

p er cen t . The sun appearedto be a variable star havin g a fluctuation in the march o f

y ears a fluctuation run n in g its courses in a few days , weeks,o r mon ths . Bo th are highly irregular The article co n tain s comparison s o f o bserved chan ges in terrestrial temperatures witho bserved chan ges in so lar radiation . It is very strikin g that theso lar chan ges produce such large and pro lo n ged temp eratureeffects .

”

In‘

sp eculation s on the causes o f Glacial Periods the suggestio nhas been put forward that sun - heat may have varied in past ages .

Apparen tly there is eviden ce that Variatio n is o ccurrin g even n ow,

and that its variatio n is capable o f producing con siderable chan gesin temp eratures o n the surface o f the earth .

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GEOLOG I CAL MAGAZ INEVO LUME LVII.

No. X.— OCTOBER,

ED ITOR IAL NO W u

AT this season of the y ear the conduct of theGEOLOGICALMAGAZINEis beset with p e cTIliar di fficulties . Owin g to the - ho lidays Our

con tributors are -

scattered far an dwide, letters have to be re—addressed'

o ften more than o n ce, an d the return of pro ofs is un avo idablydelay ed . Owin g to . distan ce from libraries

,also

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for either authoro r editor to verify referen ces, or to keep in touch

with the latest developmen ts of an y subj ect . Furthermore, thesupp ly o f reviews tends to fall o ff . An o ther great drawback to theho li day seaso n is the imp ossibility o f co llectin g in formation of recen teven ts of p ersonal in terest in the geo lo gical world . The Editorstake this opp ortun ity o f say in g that they are always grateful forn ews o f n ew app o in tmen ts to geo logical p o sts at home and abroad,an d o ther simi lar matters o f in terest to the geo logical world . Our

readers will be able to judge for themselves as to the kind o f thin gthat is wan ted . An y

“help in the commun ication o f such items willbe gratefully received . It may perhap s be permissible to mentionhere on e o ther matter of a quasi - editorial n ature . Tho se o f our

con tributo rs who desire separate copies o f their papers or . o thercommun ication s should make a p o in t o f sen di n g their o rders

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for

the same to the Editor alon g with their corrected proof. Frommo tives of busin ess eco n omy it is n ecessary to break up the typ ea lmo st immediately after the issue is p rin ted OE,

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are re ceived befo re we go to press separate Cop ies can n o t beguaran teed .

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themselves to the fie ld geo logi st reduce to exercises in_

veryelemen tary geometry . This simplicity 1s gain ed by reckonin g al l

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are thusmeasured directly up on a con toured geo logical map by the use of thescale alon e .

VOL . LVII .—No . x .

ORIGINAL ARTICLES.

Pre l im in ary No te s o n the Ge o logy o f the Nin gi HillsNo rthe rn Nige ri a.

By GERARD W. WILLIAMS,

M.CL,

F.G.S.

WITH PETROGRAPHICAL APPENDIX BY R . H. RASTALL, M.A . ,

F.G .S .

THE coun try described in the fo llowin g n o tes comprises thearea ly in g between latitudes 10°N. an d 1 1

°

30'

N. an d lon gitudes8°45

'

E. an d 10°E . ,

an d is situated in the n orthern p ortio n o f

Bauchi provin ce an d the south - eastern p ortion of Kan o provin ce ,Northern Nigeria .

.The Delimi River run s diagon ally through the area . This river,o n e o f the chief feeders o f Lake Chad,

rises on the main hydrographic cen tre o f Northern Nigeria . The three largest rivers thatrise in the Protectorate— the Delimi, Gon go la,

an d Kadun a— havetheir head - waters in a swampy ,

mo orlan d p lain that attain s itshighest elevation of approximately feet at a p o in t midwaybetween Jos an d Bukuru

,n ear to the Rayfie ld Min es main camp .

The Delimi River flows through Jos an dNarraguta,an d then p lun ges

down the Narraguta Gorge belowthe n ative market . Then ce n ortheasterly through Rafin Jaki camp , Deriko ,

an d Bon gwe lli to Lemmi .Below Lemmi the river widen s to 400 yards, an d at Guaram it isfully yards wide . Then ce the river flows past Kategum to

j o in the B eda'j i River, and the un ited stream,then kn own as the

Yo River, wi nds deviously eastward to Lake Chad . The headwaters above Narraguta drain the high land o f the Bauchi 'Plateau,

an d as bo th the main stream an d its up land tributaries drain fromthe stan n iferous gran ite o f the ’

Ngell Massif the river washes are

all tin - bearin g . The boundaries of this massif, on its n orthern side,are practically con tinuous with the boun dary o f the Plateau froniRukuba to Toro . Below the p lateau the Delimi hasbeen provedtin - bearin g for n early 50 miles —as far as Lemmi . The bulk Of thistin is n ot derived from the stan n iferous grani tes o f the p lateau ,

but is fed to the main stream by tributaries drain in g the ruggedgroup o f ran ges kn own as the Jen gre Hills, of which the Buj i Peakforms the highest p o in t . The Narraguta Gorge is excavated througha series o f gn i esses an d o ther an cien t crystallin e rocks, an d the bedrock of the river as far as Lemmi i s almo st exclusively compo sed o f

gn eisses . Below Biberi the valley widen s out in to a broad flo odp lain ,

which attain s a width o f from 10 to 12 mi les at Bon gwelli .

From the flo or of this valley rise n umerous ridges and domes of

gran ite, which decrease in number as the river flows n orth - east fromLemmi . From Lemmi to Lake Chad (with the exception of a few

iso lated gran itic hummocks) the flo od p lain widen s out on to the

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436 Major G. W. Wi l l iams

exposed in large , slightly con vex bo sses . In the bed o f“ the Sabo n

GarriRiver is an exposure ofa coarse - textured gran ulitizedmicroclin egran ite of highly acid characteristics an d immediately n orthis a small well - weathered exp osure of highly fo liated muscovitegran ite , The village o f Sabon - Garri lies at the fo o t o f three domesof gran iteFrom thevillage toDuchin Chan ya Oherigi (lit . the hill that resembles

a p ige on ’

s breast—an o ther examp le of apt n omen clature) , the trackrun s i n a gen eral n ortherly direction , passi n g between n umerousridges and domes of Sabon Garri gran ite . Ap litic in trusion s are n o tun common . Approachin g Chan ya Cherigi fo liation in creases an d inman y p laces the gran ites are stro n gly gn eisso seThe dark mass o f Chan ya Oherigi , feet, which rises feet

above the p lain level , forms a con sp icuous lan dmark . This hill isthe highest o f a series o f gran ite hills, oval in groun d p lan ,

the lon geraxis run n in g due n orth and south . The gran ites in the n eighbourho od show marked effects of dyn amo - metamorphism. The gen eralfo liation is n o rth and south , an d the main crush zon e

,which exten ds

through Gora Hill and Oban ya Oherigi , is well min eralized . A welldefin ed lode forms the crest o f these two hills

,an d is traceable for

some 2 .to 3 miles south an d n orth . Tin an d wo lfram o ccur in

n arrow, parallel , quartz - filled vein s. The coun try ro ck is an

altered gran ite con tain in g topaz . (C.C_

4 Numerous lenticularmasses of ap lite o ccur in the immediate n eighbourho od . (CC. 2

Man y’ exceedin gly rich floaters of tin ore (some assay in g up to

50 p er cen t , Sn 0 2) o ccur on the slop es o f the hills and in the valleybelow . Some of these floaters are exactly similar in app earan ceto the rich o re from the Bushveld tin mi n es (South Af rica) . In

p laces the gran ite o n the slop es of the valleys tends to‘

weather in toflat sheets , but the usual weatherin g is in to rough blocks man y o f

the iso lated boulders display a tenden cy to mushroom shape,due to the erosion by 'blown sand .

In the vicin ity of Yarde Gon gome,the main camp of the Yarde

Kerri min es,the prevailin g rocks are gn eisses , and these extend

n orthwards to Burra ,at the western en d of the Nin gi Hills . No rth

east and east from Yarde Gon gome the .Sabon—Garri gran ites comein

,and form a group o f characteristic domes in the n eighbourho od

of Min n a camp an d n ear to Dogon Daj i o n the Min n a stream .

The boundary between the Sabon Garri gran ites an d the gn eissesis ill defin ed Con tact metamorphism is en tirely lackin g , and

masses of gn eiss are frequen tly in cluded In the gran ites . In then eighbourho od o f Ke ffi Filan i vein s of p egmatite cross an d recro ssthe boun dary ,

an d the who le con tact is fo liated In a gen eral equatorialdirection . This fo liation ,

which affects bo th gran i tes an d ‘gn eisses,

was probably induced by the in trusio n of the Nin gi gran ites , thelon ger axis of which run s due east an d west .

’

The domin an t fo liation in the coun try between Chow an d Chan ya

Cherigi is distin ctly meridion al . Between Dogon Daj i and Kefi

Geo logy Of'

the Ni n g i Hi lls , Nor thern Nig er ia . 437

Filan i a broad outcrop of a_

remarkably fresh gabbro dyke (107)exp osed for a width o f some 40 to 50 yards, forms a lowridgestrikin g east and west . T his was the o n ly basic in trusionen coun tered durin g the traverse . At Ke ifi Filan i there 1s a smalloutcrop Oi

'

a somewhat gran ulitized, gn eisso se gran ite (108 ,which is differen t in character

,bo th to the Sabo n - Garri an d the

Nin gi gran ites . On ly two exp o sures were Observed, lon e fo rmin g

a few iso lated kn obs an d' the o ther formin g a low ridge run n in g

east an d west . This gran ite app ears to be in termediate in age

between the typ ical g ran ites . It . app ears to be intrusive in theSabon -

‘

Garri gran ite, but has been crushed as a result of the movemen ts that accompan ied the in trusio n o f the - Ningi massif .

- NOcon tact with the Nin gi gran ite was Observed

THE NINGI GRANITES .

North o f Keih Filan i the Nin gi gran ites are first seen in the valleyOf a small stream that heads n ear Ka an d flows south through Keffi .

The well marked con tact ,With chilled edges, is'

at this p o in t again stthe Old gran ites an d gn eisses . Travellin g eastward towards Nin g

‘ithe track skirts a low ran ge of gn eisso se hills with bars o f

harder, more siliceous rock behin d which rise the higher hillso f the Nin gi gran ite .Nin gi it

'

self,ly in g securely behin d trip le walls at the h ead Of a

small valley ,. was fo rmerly the chief village an d fort o f a Pagan

tribe Who con ducted an exten sive an d profitable trade in.

slaveraidin g . The “ n ew gran ites come in about 1 1 miles n orth of thevi llage . The con tact is clearly. marked At the p o in ttraversed the Sabo n - Garri gran ite forms large , flat, bare sheets (112)Or slightly co nvex turtle backs

,an d the n ewer gran ite rises steep ly

an d’

d-isp lays a certain horizon tal j o in tin g that resembles dry wallin go n a cyclop ean scale . The Nin gi gran ite (115) is a riebeckite gran ite ,an d is simi lar to the gran ite formin g the Kila an d Fagam massifs .

A large dyke , or series o f parallel dykes of a dark -

green rhy o lite,starts at Nin gi an d run s n orth easterly through the villages of

Ari an d Teffi . At Teffi the dyke chan n el i s occupied by porphyriesas well as rhy o lites (117, whilst p orphyries (138) an d aegirin erhy o lites (139 ) are exp osed between Wurji and Guaram .

Between Ari an d Tefli these dyke - ro cks have resisted denudationmore than the surroun din g gran ites an d gn eisses , an d stand out

bo ldly , formi n g the southern wall of the hills . Passin g north—easttowards Wurji they form numerous iso lated grassy hills an d low

ran ges . A quartz - riebeckite sy en ite o ccurs at Teffi,ly in g apparen tly

in con tact with the . Nin gi gran i tes and the porphyriesAt the cro ssmg o f the Delimi between Teffi an d Wurji o rthophyre(121 ) an d p orphyry (122) are exp o sed in the river bed,

an d expo sureso ccur in the hills n orth o fWurjiThe “

sy en ites reapp ear at Guaram,where they fo rm - several low

hills 'ly in g n ear to the town The con tact rocks in the n orth

Major G. W. Wi l liams:

easterly portion o f the Nin gi massif are syen ites an d p orphyries,the latter predomin atin g : small andesitic vein s are found i n the

p orphyries an d In the gn eisses , but n ever in the sy en ites or Nin gigran ites . North o f the p orphyries low outcrop s of Old gran ite aresometimes visible Passin g westward alon g the n orthern edgeof the Nin gi massif p orphyries and rhy o lites form the con tact rocksas far as Lumbo , but thereafter these in trusives thin out an d

x

thecon tact with the Old crystallin e ro ck is obscured by sup erficialdrifts . Near Burra con tact with gn eiss is well defin ed . TheNin gi massif measures about 30 miles east an d west , and averages6 miles in Width . The hills are ,roun ded, and the highest p o in tsattain an elevation . o f feet . The gran ite is essen tially a

riebeckite - bio tite typ e, much more fin e in grain than the an cien tSabon - Garri typ e but similar in gen eral comp o sition .

THE KILA GRANITEs .

The Ki laHills '

rise abrup tly from a level p lain . The cen tral p eak isprobably about feet in height . Although n o con tact rocksare visible chilled margin s (126) are to be seen towards the n orthernedge of the hills . The gran ite is essen tially a riebeckite gran ite

At Jugwa, n ear the cen tre o f the massif, the riebeckiteforms large crystals up to 23 in ches In len gth . The surface so il ,which is deeply banked In the valleys, is Obviously mostly o f aeo liariorigin . North an d n orth east of the hills stretch the great plain sofKategum,

who se leVe l surface of fertile Wind - bo rn e so il is un brokenby hill o r ridge .

THE FAGAM GRANITEs .

Travellin g south—east from Kila to Guaram the route fo llows themain Kan o—Nafada—Lake Chad road . There is on ly o n e exposureo f gn eiss and the so il is very deep . In a well at Yelua the waterlevel was 37 feet . The so il was comp osed of altern ate lay ers of fin esan ds an dmarly clays, the latter probably Of lacustrin e origin . NearGuaram rest - house are a few low ridges o f sy en ite an d southof the town numerous “ floaters o f rhyo lite an d porphyry o ccur .

Like the Kila Hills the Fagam gran ites rise abrup tly from .thep lain s , an d the deep so il is ban ked up the level - flo ored valleysa n d

again st the n orthern sides o f the massif .

A few exp osures o ccur about a mi le from the hills : a biotitegran ulite (130) _

forms a cluster of boulders an d n ear by the trackclimbs steep ly over an outer-op o f quartz - syen ite - p orphyryThe massif itse lf is of con siderable exten t, an d from a hill feet '

in height, which lies about 1—1 miles from the sto ckaded village ofFagam ,

the gran ite can be seen stretchin g well away to the westwardof Gadar

‘

n a . The massif 1s comp o sed of a somewhat coarse grain edriebeckite gran ite In p laces the riebeckite ten ds to formbands Pegmatite vein s con tain in g large riebeckite crystalsup to 2 in ches in len gth we re n oted Chilled margin s an d

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Major G. W. Wi l liams

Limn cea (sp . Q) . In the altern atin g san dy lay ers fragmen ts o f

Bullmus (sp . are'

sometimes found .

The valleys op en ing out o f the hills,esp ecially those facmg n orth

o r n o rth - east,are usually deeply filled with light, san dy so il

, partlydetrital an d partly aeo lian in o rigin ,

which forms a level flo or to thevalley . A remarkable feature is the un iform absen ce of watercourses in these valley s . The rain fall , averagin g _

35 to 40 in chesfalls mostly in a few torren tial down p ours durin g August an d

Sep tember . The rain s p our down the bare gran ite catchmen ts in tothe valleys, but sin k through the sCil an d do n o t form watercourses . The who le coun try becomes waterlogged, and the fewriver beds that traverse the p lain s (mere grass-

grown depression s)in dicate the gen eral direction in which the surface waters move

towards the main course of the Delimi an d Hedaji rivers . In the

floods the Delimi overflows its low banks an d spreads, .man y mileswide, acro ss the p lan es . The coun try is very similar to the Coop er’sCreek coun try o f Australia,

where on e may p erish of thirst o n eday ,an d the n ext

,10 mile wide rivers p ourin g down from the

Diaman tin a an d Georgin a coun try bear the Queen slan d flo odwaters to the lakes of South Australia . Water level In the dry seasonvaries co n siderably . In the n eighbourho od o f the hills it vari es from6 to 12 feet

,but In the plain s In creases to 40 feet . Further n o rth

east the depth in creases to 120 feet in Bo rn u provin ce .Parallel to the Delimi

_

River are a series of lo n g , n arrow,deep

lago on s, often surroun ded by p erman en t swamp s . Near to Guaramis a lago on '1%miles lon g , 250 yardswide, an d 15 to 20 feet in dep th .

fl

LATERITEs .

The horizon tally bedded lay ers o f vesicular iron ston e that are so ,

characteristic a feature of the topography o f the Bauchi Plateauan d which are i oun d throughout the coun try between Delimi an dthe Nin gi Hills are n ot developed in the light so ils east of the Kilaan d Fagam Hills . In the immediate vicin ity o f the Kila gran itescertain ban ds of san d carry con cretion s of iron ston e, but un iformlateritic sheets are lackin g .

THE OCCURRENCE OF TIN IN THE AREA .

The y ounger gran ites of the Bauchi' p lateau,which are s1mI lar to

and p robably co n temp oran eous with the gran ites of the Nin gitype , are well kn own for the ti n con tain ed In the streams drainin gfrom them . This recon n aissan ce, however, defin itely establishesthe fact that the Archaean gran ites of the Sabon—Garri type are alsostan n iferous . From Chow to Yarde

.

Gon gome all streams that drainthese gran ites carry more or less tin i n the wash , an d relatively largequan tities are foun d In the surface so ils In the vicin ity of lodes suchas tho se In the n eighbourho od o f Yarde Kerri .Near to Bon gwe lli a p egmatite sto ckwerk In Sabon - Garri gran ite

sheds a large quan tity o f tin in to the Dada Howa creek (aDelimI

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Geo logy of the Ni n g i'Hi l ls

,Nor thern Niger i a . 44 1

tributary ) . Near to Zelau the streams are markedly stan n iferous,

esp ecially tho se drain in g south an d south - east to the Delimi valley .

From the Jen gre Hills several Delimi tributaries, esp ecially theBuj i an d Zora

,carry very con siderable amoun ts o f tin in the wash .

The Nin gi gran ites y ield tin ,an d several streams in the . western

en d Of these hills are bein g worked on a very small scale . Smallquan tities Of tin

,n ever in payable amoun ts

,were foun d bo th in the

Kila an d the Pagam Hills . In these areas,however

,the absen ce o f

defin ed watercourses militates again st the econ omic con cen tratio nOf

'the shed tin . N0,tin was ever foun d in streams drain in g o n ly from

the gn eisses . For examp le , in the rivers of the Yarde Kerri GroupMi n es, the Gon gome

,Kogo , Kuskerri , an d Tip chi River an d river

flats which drain the Sabo n - Garri typ e Of gran ite produce tin inecon omic quan ity , but the adjacen t left fork of the Koten i , whichdrain s a gn eisso se area,

is abso lutely barren Of tin . This was alsoobserved in the streams drain in g a large gn eisso se area betweenBegin di an d Rahama .

If a gen eralizatio n may be permitted at this stage I would saythat tin is on ly foun d In gran ites that con tain riebeckite— an d thisview derives further supp o rt from a con sideration - Of the Meso zo Ic,

tin - bearin g gran ites of the ROpp—Mon gun a- Ex lan ds areas In thesouthern p ortion Of the Bauchi Plateau . On the o ther han d, itoccurs equally in riebeckite grani te o f bo th Meso zo ic an d Archaeanage in deed, as far as the area traversed is con cern ed it is far moreabun dan t in the Archaean gran ites than in tho se o f the Nin g i typ e .

PETROGRAPHICAL APPENDIX .

The fo llowin g n otes are brief p etrographical descrip tion s o f thero ck - specimen s co llected by Maj or Williams durin g the traversedescribed in the precedi n g pap er . Most of the sp ecimen s havebeen sliced

,but in a few in stan ces weatherin g had advan ced to o

far for this . These n otes have purpo sely been made very shortas it is hop ed to obtain further specimen s o f the mo re in terestin gtypes an d to publish a full accoun t Of the p etrography Of this areao n a subsequen t occasion . The n omen clature here adop ted must becon sidered as p rovision al , sin ce further in formation is n eeded as to

the fie ld—relation s o f some of the types co llected,an d n o attemp t

has been made to in stitute comparison s with similar rocks elsewhere .

DESCRIPTION OF SPECIMENS .

100 . Riebeckite—biotite -

gran ite .

~—This is a rock o f very coarsetexture, with cry stals of felspar ‘up to an in ch in len gth , quartz ,an d large patches of dark - co loured min erals . The largest felsparsare p erthite, the rest main ly albite , with a little orthoclase an dmicroclin e . Quartz is fairly abun dan t

,bo th as large crystals an d

as rounded blebs In the felspar, with a little mi crop egmati te . .Theferromagn esian min erals are riebeckite an d deep brown bio tite in

442“

‘

Major G. W. Wi l l i ams

approximately equal amoun t . The accessories are abundan t apatite ,some fairly large zircon s, magn etite , an d allan ite .101 . E girin e riebeckite

-

p orp hyry .

—A porphyritic rock withphen o crysts Of whi te felspar in a bluish—grey groun dmass . Thefelspars are rather lath - shaped an d up to 8 mm . in len gth . Theyco n sist Of ortho clase an d o ccasio n ally e n close a little quartz . Thegroundmass is a rather fin e mo saic Of orthoclase felspar, aegirin e ,an d riebeckite , with a little quartz .102 . Rhyolite .

—This ro ck p o ssesses con sp icuous flow- structures,shown by wavy ban ds o f dark red an d dark blue co lours . It ismuchstain ed by iron oxide an d o ther decomp o sition products, but un derthe mi croscop e shows well - marked microp o ecilitic structure

,with a

tenden cy to aggregation in spherulites . It is probably a devitrified

glassy lava Of acid comp o sition .

103. Microclin e -

gran ite .

—A coarse - textured gran itic ro ck,con

siderably crushed an d gran ul itized . It con sists almo st ' en tirely Of

quartz an d micro clin e felspar, with a very small quan tity of

muscovite . There is a slight ten den cy to micrographic structure .The rock is eviden tly Of very acid comp osition , but it is a go od dealdecompo sed, with much infiltratio n Of secon dary products alon gcracks and the boun daries of the min erals .

105 . Riebeckite - biotite -

granda— A gran itic ro ck Of coarse texture ,

comp o sed of quartz , micro clin e , subordin ate p lagioclase con siderablydecompo sed

,and riebeckite

,with a little biotite . The accessories are

i ron oxide,apatite , an d zircon .

106 . Gran ite .

—This sp ecimen con sists Of quartz , decomposedo rtho clase with some plagio clase n ear o ligo clase , an d patches o f a

green Chloritic min eral , which may represen t biotite . The rock hasbeen much crushed

,as is shown by the ben din g Of cleavages an d the

twin lamellae Of the plagioclase .107 . Gabbro .

— A remarkably .fresh rock , con sistin g Of plagioclasefelspar, diallage , ho rn blende, an d a little bio tite . The felspar hasa refractive in dex higher than that Of Can ada balsam,

an d showsextin ction an gles up to 30 degrees . It is therefore o f a basic charactern ear labradorite . The diallage is very pale brown ,

wi th thecharacteristic purp lish in clusion s . There is also some co lourlessaugite . The brown horn blen de is Often seen as a sort Of graphicin tergrowth with the pyroxen e , all the en clo sed patches common lyshowin g the same o rien tation . There is a little bright chestnutbrown bio tite (lepidomelan e) . The on ly accessory min eral is a verylittl e magn etite an d n o n ephelin e o r an alcime could be detected .

The extraordin ary freshn ess of this ro ck suggests that it is o fmuchlater date than an y Of the o ther sp ecimen s .

108 an d 1 10 . Biotite—gran ite .

— B0 th these sp ecimen s, which are

almo st iden tical , are gran ulitized gn eisso se gran ites , comp o sed Of

quartz , Often In roun ded blebs In the felspar, large micro clin es, an da l- ittle plagio clase . There are here an d there small patches of

microp egmatite . The co loured con stituen t is Olive brown biotite ,

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44 4 Major G. W. Wi l l iams

fe lspar i n a fin e groun dmass . It con sists en tirely of orthoclase an diron

‘

o x ide , the latter represen tin g some ferromagn esian min eral .The felspars o f both gen eration s are prismatic in form ,

an d thestructure o f the groun dmass is typ ically Orthophyric . This is thedyke - facies o f a sy en itic rock .

122 an d 123. Porp hyry ,

— A con sp icuously p orphyritic rock,with

phen ocrysts of orthoclase in a fin e groun dmass o f quartz,ortho clase

,

an d red iron oxide . The orthoclase is much decomp osed,an d the

o rigin al character Of the ferromagn esian min erals is un determin able .The groun dmass is microgran itic in structure .124 . E girin e

- riebeclcite -

gran ite .

— A remarkably fresh rock , con

sistin g essen tially Of quartz, p erthite , aegirin e, an d riebeckite . The

felspar is en tirely microp erthite of a fin ely in tergrown typ e , inidiomorphic crystals Of tabular form . The quartz is in terstitialan d the lastmin eral to cry stallize . Ferromagn esian min erals are notabun dan t chiefly emerald-

green , aegirin e in idiomorphic prisms

with the characteristic slight p leo chro ism an d small extin’ction an gle ;there‘ are also a very few crystals Of pale - brown or co lourless augite .Deep blue riebeckite is much less abun dan t than aegirin e the largercrystals are . n early opaque even in a very thin slice . The on lyaccessory seen is a little magn etite .125 . Riebeckite - aegirin e

-

gran ite .

— This ro ck is clo sely related to

the last,the chief differen ce bein g the predomIn an ce of riebeckite

over aegirin e, an d a slight ten den cy to micrographic structure . Al l

the min erals show precisely similar characters an d further description is un n ecessary .

129 . Biotite - augite- syen ite .

— A rock of fairly coarse texture an deven grain , con sistin g o f felspar, bio tite , augite , an d riebeckite . Thefelspar is chiefly p erthite with a subordin ate amoun t o f

, p lagioclase ,havin g a refractive in dex lower than Can ada balsam (albite) . The

bio tite,which is very fresh, is Of a deep chestnut brown co lour, with

very stron g p leochro ism ; the augite is pale - green with slightp leochro ism an d very stron g birefrin gen ce therefore , probablyferriferous . There is a little deep blue - green riebeckite in raggedprisms, o ften in tergrown with augite . The structure is hy p idiomorphic, with a ten den cy to parallel arrangemen t in the felspars ;a typ ical sy en ite . Q

130 . Biotite—gran ulite— An aggregate Of quartz , perthite , and

red - brown bio tite , showin g a gran ulitic structure . Some largecrystals Of felspar have a somewhat p orphyritic tenden cy ,

but o therwise the structure is even -

grain ed and granularg of the aplitic typ e ._The mo st n oticeable feature is the , in ten se co lour Of the biotite(lep idomelan e) , which is quite Opaque in the p o sition Of maximumabsorp tion .

131 . Hybrid rock — Large phen ocry sts Of ortho clase felspar,somewhat rhombic in form an d full Of in clusion s , in a groun d

mass Of very variable texture, comp o sed Of quartz , p erthite, ortho '

clase , an d green horn blende . In parts the groundmass is granulIt'

Ic

Geo l ogy of the Ni n g i‘ Hi l ls

,Nor thern Nig er i a . 445

an dmicrographic, while in other parts themin erals show the relation scharacteristic of a do lerite . The specimen also con tain s a go od -man y

p ebbles of quartz,with corro sion borders

,Obviously xen o lithic, an d

it is probable that the who le thin g is a mixture ro ck, comp o sed

o f alkali - gran itic and alkali - do leritic materials . Further materialis n ecessary to elucidate this po in t .133and Riebeckitc-

gran ite .

— A gran itic rock o f coarse texture ,co n sistin g exclusively o f quartz , white p erthite , an d riebeckite .Quartz is very abundan t an d shows a slight ten dency to graphicin tergrowth with the felspar . The riebeckite is o f a deep prussianblue co lour, visible even in the hand - sp ecimen ; it forms irregularpatches

,an d o ccasion ally lo n g idiomorphic prisms . The o n ly

accessory Observed is a small amoun t of deep’

purple fluorspar,o ccasion ally vi sible even in the han d - sp ecimen ,

but chieflymicroscop ic .

135 . Riebeckite -

p egmatite .

—A small han d sp ecimen associatedwith the two forego in g , of fairly coarse p egmatitic character

,con sists

o f quartz , flesh red felspar,an d large prisms of riebeckite up to two

inches In len gth .

137 . Biotite - ap lite Vein—This specimen con sists of a perthite

gran ite o f fairly coarse texture pen etrated by a vein of ap liticcharacter, with red brown bio tite .138 . Augite

-

p orp hyry .—Phen o crysts of pin k an d o ccasion ally

white felspar In a matrix of quartz, f elspar and augite , n ow repre

sen ted main ly by some Chloritic min eral . The large white felspars ,which app ear to be albite, have a border of p ink o rthoclase

,an d

the p in k felspars are orthoclase so far as they can be determin ed :all are con siderably decomp osed . The groun dmass is rather fin ein texture, main ly ortho clase“ in irregular patche s with pale greenau ite

,chlorite an d a little in terstitial quartz , with some Opaque iron

Ore . This is the hypabyssal facies of a sy en itic rock, with domin an tp o tash .

139 . E girin e rhyolite .

— A grey ish green ro ck with ‘

very con

spicuous flow- structure . It con tain s phen o crysts of quartz andp erthite felspar In a groundmass of variable texture : some bandsshow a microgran itic structure , while o thers are fin ely mi cro

crystallin e . The min erals of the groun dmass are quartz , felsparan d aegiri n e , the latter In small shapeless o r elon gated grain s, withan o ccasion al larger prismatic form: the latter o ccur chiefly In thecoarser bands . No o ther ferromagn esian min erals were observed .

140 . Graphic Gran ite— The min erals Of this '

sp ecimen are“

too

much decomp o sed for certain determin ation . The felspar was

probably ortho clase , sin ce n o indicatio n s Of po ly syn thetic twin n in gcould be seen . The on ly n oticeable feature i s the well markedmi cro graphic structure . There are a few large zircon s and a littlemagn etite .CC . 3. Biotite - A ro ck of granulitic or ap litic‘

structure, con sistin g of quartz

,micro clin e , o rthoclase , and bio tite .

446 Geo logy of the Ni n g i Hi l ls, Norther n Nig er ia .

The quartz and felspar are in some parts micrographically in tergrown , while elsewhere the structure is granular- hyp idiomorphic .

The bio tite is o live—brown an d con tain s in clusion s o f allan ite withp leo chro ic halves . This rock app ears to be very simi lar to Nos .

108 and though fin er in texture .CC . 4 . Top az

- rock.

—This is a sp ecimen o f the apli tic rockassociated with the tin - tun gsten lodes : the actual slice was takenabout 1 in ch from the edge of a n arrow lode Of this kind . Itco n sists o f quartz

,some highly decomp o sed material represen tin g

felspar, topaz , an d red an d black p atches which p robably in cludebo th iron oxide an dwo lfram . Quartz

,which is very full of bubbles,

is the mo st abun dan t min eral,fo llowed by topaz . Most of the

felspar has comp letely disapp eared,an d the specimen is an excellen t

examp le of a pn eumato lytic tOpazified ro ck,allied to grei sen In its

man n er Of formation . Cassiterite could n ot be iden tified in theslice, though the lodes carry tin .

CONCLUSIONS .

The micro scop ic examin ation of these specimen s con firms in all

resp ects the results arrived at by Maj or Williams from his fieldObservatio n s . It is quite clear that there are here three typ es Of

ign eous ro ck, as fo llows1 . Highly granulitized an d crushed grani tic gn eisses, rich in

mi cro clin e , with little o r n o ferromagn esian min eral (103, 109 , 111 ,These app ear to be essen tially p o tash gran ites .

2 . Slightly crushed gran ites in trusive in to the a bove , sp eciallycharacterized by p erthite , riebeckite , an d aegirin e , an d thereforecharacteristically rich in soda (100 , 105 , 106, 113,

Numbers108, 1 10, C.C. 3

,C.C. 4 probably belon g here . This series con tain s

accessory allan ite .3. A still later series of soda gran ites, quite free from kataklastic

structures,with perthite , riebeckite , an d aegirin eThese are accompan ied by smaller in trusio n s o f sy en ite

an d a con siderable variety of sy en ite dykes an d o ther small in trusion s121 , 122, 123, 129 , This series is believed

to be ofMeso zo ic age .

The on ly basic ro ck observed (107 is so differen t from the rest,and so con sp icuously fresh an d un altered that it may with someconfiden ce be referred to the Tertiary p eriod .

The first group as here defin ed corresp on ds to the o lder gran iteso f Falcon er’s classification .

1 The Secon d group are believed to bealso o f Archaean age , although they app ear to have undergon econ siderably less dyn amicmetamorphism. It Is as yet imp o ssible tostate Whether an y o f the hypaby ssal typ es belon g to this group .

The thi rd group ,which may be described co llectively as the Nin gi

series, has eviden tly un dergon e much more differen tiation ,sin ce it

in cludes a large n umber o f dykes an d small masses o f sy en itic1 The Geo logy and Geograp hy of Northern Nigeria, Lon don ,

19 1 1 , chap . iii .

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GEOL . MAC , 1 920 . PLATE VIII .

FIG . 1 .-

'

l‘

he great diamon d m in e at Sopa ,n ear Diaman tin a ,

Min as Ge rae s ,Braz il . No te the excavati on in the so ft sericitic sch ist. The surroun din gcoun try is hard quartzite .

FIG . 2 .

— '

1‘

he gre at diamon d min e at Boa Vista , n ear Diaman tin a , Min as Gerae s ,Brazi l . No te the fi ssure - l ike excavation Of the min e . The surroun din g

p lateau is fo rmed Of hard quartzite s .

To face 10 .

R . R . Wa l ls— Diamon d P ip es i n Brazi l . 447

comp o sition ,an d some of the Sp ecimen s here described as rhyo lites

show all the characteristics o f lava - flows .

From the min eralogi cal p o in t o f vi ew, the most in terestin g featureso f the later Archaean an d Meso zo ic ign eous ro cks is the domin an ceof alkalin e characters . The felspar is main ly p erthite, while theferromagn esian min erals are chiefly riebeckite an d aegirin e ; themagma was therefore rich in soda however

,n o n ephelin e has been

foun d in the more basic (sy en itic typ es) .Although tin ,

wo lfram,an d topaz are abun dan t in the area ,

an d

fluorspar o ccurs lo cal ly ,it is“ remarkable that amon g these sp ecimen s

n ot a sin gle occurren ce of tourmalin e has been Observed . It is eviden tthat the pn eumato ly tic phase was characterized by fluorin e to theexclusio n of bo ro n .

The Ex iste n ceoo f Diamo n d- be arin g Pip es

”in Braz il .

By ROBERT R . WALLS,M.A . , B .Sc .

(ELATE VIII . )

THERE has been great con troversy as to whether or n ot thereexist in ‘

Brazil diamo n d - bearin g p ip es such as are foun d inSouth Africa . That somethin g o f the kin d Should exist seems to bepretty Well ackn owledged, but an y eviden ce in supp ort of thediscovery o f a pipe has always been very meagre . The fo llowin gObservation smade by the writer on a fewmin es in the n eighbourho odof Diaman tin a, in the state o f Min as Geraes, might be of in tereston this somewhat vexed quest ion .

The writer had n o practical exp erien ce whatever o f diamond

mi n es when he arrived in Brazil , and was on ly drawn in to the subj ectby acciden t . When study in g the san dsto n es an d quartzites of theSerra

_do Esp in haco he foun d that in man y places these had been

stewed up as it were an d metamorpho sed in to ro ck cry stal .There was n o sign o f a gran ite or ap lite in trusion in the n eighbourhood, but these crystal formation s

_

all lay clo se to the greatdiamon d min e at Sopa,

an d from the field eviden ce alon e it seemedas if this latter must have been an ign eous in trusion .

The ro cks o f the district are all hard “ quartzites,remarkable for

the horizon tality an d regularity of their beddin g . The great min etakes the form o f a fissure , a mile o r more in len gth, an d seems to

run down vertically through the bedded quartzites, although theactual con tact was n owhere expo sed . This pip e or fissure is filledwith a sericitic schist crowded with small crystals an d con cretion so f iron - o res . It is green in co lour, an d so soft that it can be easilybroken down with wo oden spades an d bateas . This green earthis then washed by n egro labour, an d the iron - ores an d diamo n ds are

left as a heavy residue . The green earth bleaches to a white clay ,

an d is . foun d all down the streams min gled with quartz sand . TheSopa min e lies on the very summit Of the ridge of the Serrado Esp in haco ,

an d the streams which run down from it are

4 48 R . R . Wa l ls fi Diamon ol P ip es i n Brazi l .

diaman tiferous for hun dreds o f miles .

5 Man y imp ortan t placermin es are worked in the beds o f these rivers .

The field eviden ce therefore— the lon g fissure In the quartzitesan d the trail o f diamonds from then ce to the sea- seems to in dicatethat this was a p ipe of ign eous o rigin an d the origi n al home o fthe diamo n ds. But the sericitic schist with its co n cretion s an d(crystals Of iron - ores which fills the fissure differs con siderably fromthe Kimberlite o f the South African min es . Un fortun ately alsoBrazilian geo logists o f con siderable stan din g have co n ten ded fo r so

lo n g that there were n o pip es in Brazil equivalen t to the Kimberlitep ip es o f South Africa that to establish the fact of their existen ce willrequi re much more eviden ce o n the gen eral geo logy of the district .Besides Sopa two o ther mi n es o n the summit Of the Serra do

Esp in haco exhibit the phen omen a o f pip es . On e o f these lies a tBoa Vista, some 20 Or 30 miles south east o f Sopa . The writervisited this min e an d foun d it bein g worked un der the direction o f

Mr . Drap er, an en gin eer who had had co n siderable exp erien ce inthe pip es Of South Africa an d who recogn ized thi s as an ign eouspip e , though highly metamorphosed . The asp ects o f these two min es.are shown o n the accompan y in g p late , where they are seen as longfi ssures surroun ded by the hard ho rizo n tally bedded quartzites .

The third min e at Sao Joao de Chapada ‘

lies about 15 mi les n orth ofSopa ,

an d though the writer did n o t visit it he was assured by min erswho had worked there that it was exactly similar to the min e atSopa . These three min es occur in separate and. distin ct outcrops o fsericitic schist

, an d the in terven in g coun try is covered en tirely bythe quartzites . These quartzites app ear to

'

be of con siderablethickn ess in the n eighbourho od o f Diaman tin a an d to lie directly on

the crystallin e comp lex .

The geo logy of the diamon d region o f Bahia farthernorth o n theSerra do Esp in haco Is n ow pretty well kn own owin g to the researcheso f Derby ,

Bran n er, an d Cran dell . ‘ The fo llowin g strata coun tin gfrom below upwards have been mapp ed there

Re ce n t formation s .

Salitre Se rie s .

Estan cia Se rie s .

Lavras Serie s .

Paraguassu Series .

Jacuip e Fl in ts an d Cabo clo Shale s .

Tombador Se ries

Jacobin a Serie s .

Cry stal l in e Comp ler

s

we

a

e

fl

ws

With the exception o f the first of these they'

are all sedim‘en taryd ep o sits . The Lavras series is the o n e which co n tain s the prin cipaldiamond mIn es, and the in feren ce Is , therefore, that the diamon dshave been obtain ed from the disin tegration o f Older ro cks . Thi s o n lyl eaves us five series o f strata with their con temp o ran eous ign eousin trusion s . Again the gen eral eviden ce seems to p o in t to the factthat the drain age has alway s been as at presen t from the south or

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Metamorp hi sm of South Austra l ian Do lomi tes . 449

from what the writer calls the high p lateau of south - east Brazil .ThisWould in dicate that the diamo n ds n ow foun d in theLavras seriesin Bahi a had their origin in an ign eous ro ck somewhere in the highp lateau to the south . Carry in g the in feren ce still further wemightassume that the sudden appearan ce o f the diamonds In the Lavrasseries an d their absen ce from earlier strata (which seems to be thesummary o f the eviden ce o f Derby ,

Bran n er, - and Cran dell) wouldin dicate the formation o f the diamon d in an ign eous ro ck of laterParaguassu age . The weatherin g o f an in trusive rock o f this periodwould then give rise to the diamon d—bearin g Lavras series .

The quartzites of the Diaman tin a region in Min as Geraes are

supp o sed to be con temp oran eous -with the Jacobin a series of Bahia .

The overly in g strata have been removed by den udation . If thea ssumed p ip es of S0 pa,

Boa Vista, an d elsewhere are of lateParaguassu age there must have been con siderable erosion withremoval o f their diamond con ten ts . Thi s would certain ly accoun tfor the rich dep o sits in sedimen tary rocks lyin g to the n orth . Thep resen t section s are the deep - seated remn an ts o f p ipes which n o

doubt towered above their presen t sites for man y hundreds o r eventhousan ds Of feet .Al l the above - men tion ed rocks

,with the exception of group 9 ,

are of early Palaeo zo ic age , and have been highly metamorpho sed .

Whether the sericitic schist of Sopa is the metamorphosed remn an to f an ign eous in trusion , and, if so , by What chemical pro cess it hasbeen so metamorphosed is a question

'

for the geo logical chemi st .The commercial asp ect o f the questio n ,

'

the discovery of the origin alhome Of the diamond which has scattered its wealth over such greatareas of sedimen tary rock in “

Brazil, would certain ly warran t a closerinvestigation in to the subj ect .

The Me tamo rp hism o f the Pre - Cambrian Do lom ite s o f

So uthe rn Ey re Pe n in sula, So uth Austral ia.

By C. E. TILLEY, B.Sc A .I .O Emmanuel Co llege , Cambridge .(PLATE IX . )

In troduction .

The Hutchison SeriesDo lomites Of the Hutchison Serie s .

(a ) The Sleaford Bay Section .

(6) Do lomi tes of the Hutchiso n Area .

Chemical Chan ge s in vo lved in Metamorphism .

The Calc - magn esian Sil icate Rocks of the Hutchison Series .

a ) D iop side Ro cks .

(6) Diop side Microclin e Rocks .

The Chemistry of the Deve lopmen t Of the Calc - magn e sian Silicate RocksCon clus io n .

INTRODUCTION .

THE basemen t platform of Southern Eyre Pen i n sula con sistsof a series of ign eous and metamorphic rocks of pro - Cambrian

age . Risin g from ben eath the Meso zo ic an d Tertiary strata Of the

VOL . LVII .—NO . x . 29

450 G. E . Ti l ley— Metamorp hi sm of

Nullarbor plain s, they may be regarded as a south - easterly prolon gation of the great pre - Cambrian Shield o f Western Australia .

The p latform is for the mo st part withi n a few hun dred feet o f sealevel, an d large areas of the region are covered - by the products o f

lon g - con tin ued weatherin g o f the o lder ro cks o r by siliceous dep o sitso f late Tertiary age . The best sectio n s for geo logical study are thoseexposed alon g the co astlin e, and in the hilly areas of Hutchisonan d Warrow .

The gen eral discussion o f the sequen ce of the pre - Cambrian inthis area wi ll be reserved for an o ther p lace ,

‘

an d this pap er willbe limited to a descrip tion of certain metamorpho sed sedimen tsembraced within the o ldest group of ro cks that have been recogn ized,an d which it is propo sed to design ate the Hutchison series .

HUTCHISON SERIES .

On ly remn an ts of this terrain are n ow exp osed to view,the series

havin g been broken up by the great in trusion s o f ign eous gn eissesthat succeeded . To this group of ign eous rocks

,the n ame

Flin ders series— is given ,from the hun dred an d coun ty in which they

attain a widespread an d typ ical developmen t . Fragmen ts o f the.Hutchison beds have been en gulfed in the Flin ders gn eisses, and

these can be recogn ized at po in ts remote from typical exposureso f the Hutchison series . There is abundan t eviden ce that thissedimen tary terrain has been invaded an d in ten sely metamorphosedby the succeedin g Ign eous in trusion s . The best exp osures of theHutchison seri es are develop ed alon g the coast of Sleaford Bay ,

an d

in the hun dred ofHutchison In the hilly district west of Tumby Bay .

At various in termediate po in ts between the Sleaford Bay and

Hutchison areas, these ro cks emerge frOm ben eath a man tle o f

Weathered products, but n o exten sive unweathered outcrop s haveas y et been recogn ized. In a n orth - easterly direction In the coun tyo f Jervo is

,R . L .

" Jack has described do lomites associated withschists and gn eisses, and doubtless these ro cks represen t the sameseries alon g the . same lin e of strike . Un doubtedly the best expo sureso f these rocks are those outcroppin g on the shores of Sleaford Bay ,

n ear Sleaford mere . Here in a section of less than half a mile a mo stcomp lex series of sedimen ts is foun d, p en etrated by gran ites and

pegmatites of the Flinders series .

The beds,n ow

'

exp osed in a highly metamorpho sed con dition ,

comprise mi ca schists, garn et gn eisses, graphite schists, graphitegarn et gn eisses, quartzites, do lomites, an d c

'

alc- magn esian si icate

ro cks . The beds strike in a n orth—south direction ,with a hi gh an gle

Of dip‘

to the west (75 degrees) to vertical . Subsidiary fo ldin g an d

faultin g have been observed . On the west they are boun ded bygrani tes an d gn eisses of the Flin ders series, while on the east the bedsdisappear ben eath calcareous sand rock and travertin e , whichhere forms the coastlin e till the ign eous ro cks o f Flinders in terven e,n ear the Curta Isles, acro ss the Bay .

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G. E . Ti lley— Metamorp hi sm of

(a) The Sleaford Bay Section .

The do lomiteslo f the Sleaford Bay area are limited to a com

paratively small exp osure on the shore—lin e . Here they are asso ciatedwith schists and gn eisses in truded by p egmatites an d gran ites insill like fashio n .

As exp o sed on the beach, the marble outcrop is bounded on theeast by a sill o f horn blende gran ite an d o n the west by a coarsepegmatite At its border it i s rep laced by iro n sto n e . The exactthickn ess can n o t be made out owin g to the po orn ess of '

exp o sure s,and large blo cks eviden tly n o t in situ are presen t o n the beach n earat han d . When fresh i t i s a compact , cream - co loured ro ck

,but o n

weatherin g its compo site character is in dicated by the selectiveweatherin g , the calcite, do lomite, an d n ew f- Ormed silicates bein gattacked differen tially , leadin g to ho llows and pro j ectio n s, the lattercon sistin g main ly o f do lomite with un altered silicates . Thin section so f these rocks when examin ed under the micro scop e show an

in terestin g suite o f min erals , which in clude calcite , do lomite ,forsterite

,an d an amphibo le o f the eden ite - pargasite group . Rarely

phlogop ite an d di op side may be seen .

Dealin g with these mi n erals we have :(i) Calcite .

—Abun dan tly presen t in roun ded grain s up to 15 mm .

in size . Cleavages are usually presen t an d twin n in g lamellae (on theplan e 01 12) are rarely to be observed . In section s which Show therhombohedral cleavages in tersectin g at the cleavage an gle o f

74 degrees the twin n in g lamellae are seen to in tersect the acute an glebetween the cleavages,and are parallel to the lon ger diagon al of. therhombohedron .

The distin ction between calcite an d do lomite was primarilye ffected by usin g Lemberg ’s so lution s . Un covered section s weretreated with a dilute so lution o f ferric '

chloride for two minutes,washed an d then immersed in ammon ium sulphide so lution , washedan d finally treated With p otassium ferricyan ide , by which theprecip itated ferrous sulphide is co nverted in to Turn bull’s blue .By this mean s calcite is stain ed blue, whilst do lomite remain s

un stain ed . This method has been found very satisfactory in

differen tiatin g these carbon ates . The calcite grain s in these rocksare remarkable for their turbidi ty an d the do lomite for its limpidity .

The clouded character IS due to minute in clusion s, Some o f whichare tran sparen t an d o f high refractive in dex . They are often quiteragged in outlin e , an d app ear n ot to be disp osed alon g an y particulardirection . Others, usually more minute , are Opaque, and theirn ature is n ot clear . In some calcite grain s there are small granulesof do lomite, clear an d un stain ed, suggestive o f a rami fyin g in tergrowth . In on e slice (115a) a primary twin o f calcite - twin -

p lan e(1011 )—f - is shown ,

the two parts havin g their vertical axes in clinedat approximately 90 degrees, and the twin bein g boun ded by prisman d rhombohedron faces .

South Au stra l ian Do lomi tes . 453

(ii) Do lomite — As remarked above,this min eral has been

di stin gui shed by its un stain ed characterwhen the section is treatedwi th Lemberg ’s so lutio n . When ever

_it shows an y defin ite outlin e ,

this outlin e is always idioblastic towards calcite,the reverse n ot

bein g seen . The marked limp idi ty is a n o table feature . Con trary tothe usual statemen ts in the literature

,the do lomite in these slides

is characteristically twin n ed, o ften showin g rather wide hemitrop eban ds . In fact, it may be said that do lomite is more o ften twin n edthan calcite . The twin n in g law seems also to be o f a difleren t typeto that of Calcite . The p lan e 01 12 in do lomite is n ot a glide ‘

plan e ,and the twinn in g in these slides would correspon d to twin s o n

0221 . Where a section shows the two cleavages in tersectin g at therhombohedral an gle, the .twin bands in tersect the obtuse an glebetween the

'

cleavages'

and are parallel to the shorter di agon al o fthe rhomb . This po in t serves to distin gui sh it from calcite . In

addition,then ,

to the stain in g differen tiation for these rocks, we canapp ly the fo llowin g criteria

(1 ) Twin n in g in do lomi te is at least as common as in calcite ,an d is o ften more so . Moreover

,the twin n in g is of a

_

differen t

typ e . In do lomi te the twin plan e is 0221 , an d in calcite 01 12 .

In favourable section s, such as tho se showin g the cleavagesin tersectin g at the rhombohedral an gle, the lamellae cut thein tercleavage an gle, such that in do lomi te they are usuallyparallel to the shorter diagon al o f the rhomb

,an d in calcite

are parallel to the lo n ger diagon al . The twin nin g in do lomitewould app ear to in dicate that the p lan e 0221 is also a glide plan e .(2) Where the on e mi n eral exerts its form again st the other

do lomi te is always the idioblastic min eral .(3) Do lomite is usually of a remarkably limp id character,whilst calcite is invariably turbid,

owin g to th e presen ce ofminutein clusion s . The sign ifican ce of this wi ll be dealt with later .

This feature can be safely used to differen tiate calcite and do lomi tein the rocks under discussion

,and is the mo st importan t Of the

three criteria .

(iii ) Forsterite .

— Builds roun ded grains or crystals with elon gationparallel to the c axis in size up to 15 mm . ,

rarely larger . In somegrain s the 010 cleavage , the trace bein g parallel to the elon gation ,

is very distin ct, but it may be comp letely absen t . Apart from its

characteristic decomp osition p roducts, it is distin guished by its

large op tic axial an gle, positive, sign ,an d the p o sition of the op tic

axial p lan e with referen ce to the 010 cleavage . The _

characteristiccracks an d the serp en tin ous decomp o sition parallel the o ccurren ceo f its ferriferous member in the erup tive ro cks . In some

_

sectio n s(1 15) the forsterite is n ow rep resen ted by aggregates o f opal an dcalcite . The determin ation o f calcite within the forsterite outlin ewas settled by a stain in g test .

454 G. E. Ti l ley— Metamorp hi sm o f

(iv) Eden ite .

— This is a clear, co lourless mi n eral , idioblastic, witha moderate refractive in dex, which o ccurs sparin gly in these ro cks,embedded in calcite o r do lomite .Several section s show the typ ical amphibo le cross - section cleavagesin tersectin g at an an gle of 124 degrees . The crystals are opticallyp ositive, an d extin ction s o f 25 degrees have been observed. Thesep rop erties do n ot corresp ondwith those of ordin ary tremo lite . Moreover

, a basal section y ields on ly a very low in terferen ce co lour,an d in con vergen t light such section s are seen to be almost n ormalto an op tic axis . The optic axial an gle is n ot large , an d the plan eo f the op tic axes bisects the o btuse in tercleavage an gle as in n ormalamphi bo les , These characters serve to iden tify the min eral as a

member o f the eden ite - pargasite series . If we restrict the n ameeden ite to the co lourless members Of this group , then this mi n eralmust be

,

classed as eden ite .Kreutz 1 has described a pargasite, from Pargas, Fin land, con

tain in g 108 3p er cen t A1203, 15 6 p er cen t FeO,0 76 p er cen t Fe zOg .

The Optical prop erties are given as R . I. D.R .

'

0195,op tically p ositive, 2V 59 degrees, Z AC 27 degrees .

W. E . Ford,

2 in an op tical study Of the amphibo les, describes an

eden ite from Gren ville town ship,Can ada ,

con tain in g p er cen tA1

20 ,” FeO=0°

42,Fe 2O3=0

'

42 . The double refraction approximated'

020,

op tically p ositive, 2V 56 degrees, an d the extin ctionZAC 29 degrees .

Co omaraswamy ,in describin g the crystallin e limeston es o f

Ceylon , gives the an alysis of an alumin ous tremo lite,A120 3 13 76 .

The op tical prop erties are n ot given ,but material from an o ther

locality gave extin ction s on 110 cleavage flakes of 17 degrees,which would approximate the eden ite values on 010 .

In view o f these descrip tion s, an d the parallelism o f the opticalprop erties of thesmaterial in those do lomites, with tho se describedfo r the eden ites by Kreutz an d Fo rd,

’

we can have little doubt inassign in g this min eral to the eden ite group .

Un fortun ately the material at disp osal an d the comparativescarcity of the mIn eral in the ro ck, has n ot en abled a chemicalan aly sis to be made . Some section s, cut parallel to the verticalaxis showin g a sin gle cleavage, are with difficulty distin guishablefrom co lourless diop side, the op tical Orien tation Of which is clo selysimilar .

(v) Alteration Products of Forsterite .

—Fo rsterite is, as has beenn o ted, usually in part, or who lly rep laced by o ther min erals, amo n gstwhich serp en tin e , calcite

,rarely do lomite o r magn esite, an d Opal

are the . chief .

Serp en tin e may be develop ed to the exclusion o f the carbon atesor Opal . Calcite has been defin itely proved in certain cases, an d a few

1 S . Kreutz, Min . Mitt .

,vOl . x xv11, 1908 , p . 249 .

2-W . .E . Ford

,Amer . Journ . Sci . , vo l, xxxvi i, 19 14 , p .

3 A . K . Co omaraswamy , Quart . Journ . Ge o l . So c . , vo l . lviii , 1902 , p . 41

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'

4 56 G. E . Ti l ley— Metamorp hi sm of

cases been sufficien t detrital silica to combin e with all magn esia tofo rm forsterite .Dealin g with these min erals we have(i) Sp inal — This min eral is characteristically o f a light -

greentin t

,buildin g little rounded grain s or more rarely idioblastic . The

green co loration is to be ascribed to ferrous iro n ,indicatin g amember

o f 'the pleon aste group . It may be [present iso lated in calcite ordo lomite, and also abuttin g o r en closed in o rigi n al forsterite grain s,which n ow con sist of forsterite residues surrounded by serp en tin e.

In some examp les the spin el is bordered by a thin rin g o f serp en tin e ,p resumably derived from it . Marbles con tain in g abun dan t lightgreen spin el are well develop ed in the n orth - eastern corn er of

section 63, hundred OfHutchiso n .

(ii) Phlogop ite .

— This is an imp ortan t co n stituen t o f the marbleso f this area . It is co lourless to a very light brown ,

an d is Oftenmuch ben t an d con torted . Cleavage - flake s give an in terferen cefigure n ormal to an acute bisectrix, but the Optic axial an gle is so

small that the op en in g o f the hyp erbo lae is very slight . It .showsperipheral an d in tercleavage alteration to a Chloritic product .(iii) Ap atite .

-Is develop ed in little rounded to sub hexagon algrain s, showin g un iaxial n egative character . It is common lyasso ciated with ro cks In which phlogopite 1s presen t .(iv ) Oh-rysoti le

- Asbestos .

—Occurs in irregular vein lets in y ellowgreen serpen tin e in the gorge Of the Min e Creek . The fibres are

a lways elon gated at right an gles to the len gth o f the vein s .

Un der the micro scop e the asbesto s is seen to be presen t inan astomo sin g vein s

,cuttin g across the mass of serp en tin e . The

refractive in dex is less than that o f C. b alsam . It is opticallyp o sitive, and the optic axial p lan e is parallel to the len gth Of thefibres . The elo n gation Is p o sitive an d the extin ction is Straight .(v) Diop side .

- Occurrin g In the samemarble are n odularmasses ofgreen diop side, associated with vein quartz , to which the fo rmationo f di opside is due . Where the quartz vein has pen etrated the

do lomite it is surrounded by a rin g o f the green silicate . The

pyroxen e has n o t been defin itely found In this lo cality o ther thanth this association

,but In o ther places it o ccurs as a n ormalproduct.

o f metamorphism n ot invo lvin g addition of material .(vi ) Forsterite .

—The serp en tin ization Of the o livin e o f these rocksis accompan ied by a separation o f magn etite granules at the borderso f the pseudomorphs and betrays the origin al presen ce of a ferriferousfo rsterite . There must still be con siderable iron presen t in some ofthe serp en tin e , judgin g by the stren gth of co lour that is developed

In o ther cases the forsterite is clear an d un alteredHaematite may take the p lace of magn etite borderin g serp en tme

pseudomo rphsIn the absen ce Of silica the ro ck has recrystallized without chan ge .

No . 307, from an outcrop in section 804 treated with Lemberg’sso lution , remain ed un stain ed with the excep tion of a very small

South Austra lian Do lom i tes .

‘

457

amoun t o f calcite . The specific gravity is in con formi ty -with thisdetermin ation ,

bein g 2 84 . There are a few flakes o f phlogo p ite an da few grain s o f an amphibo le , possibly . eden ite .Nodular masses of y ellow green serp en tin e are presen t In a zon e

o f the same outcrop up to 2 in ches In diameter, an d o ccasio n allylarger masses are met with . It is with these that the chryso tilevein s are associated . The specific gravity of homogen eous fragmen tso f the serp en tin e varied from 2 55 to 2 56 . The sp ecific gravity o f

the o phicalcite ro cks is close to 2 ‘

70 , an d vary from 2 69 to 2 72 .

This can be ascribed to a chan gi n g di stribution of serp en tin e andcon curren tly the comi n g in of do lomite .

CHEMICAL CHANGES INVOLVED IN METAMORPHISM .

The mi n eralogical features of this sui te of ro cks are thosecharacteristic Of metamorphism of the thermal type, and there isn o eviden ce that shearin g stress has p lay ed any imp ortan t rOle .

In the ro cks un der di scussion we can also exclude magmatic addition sas bein g in operative, with the po ssible excep tion o f such a vo latileco n stituen t as water . It is clear that apart from detrital impurities,like silica an d alumin a

,the sedimen ts were true do lomites o r

do lomitic limeston es, with a high p ercen tage of magn esia . As to

the o rigin o f the do lomitization it is clearly an terior to this epo cho f metamorphism,

an d there Seems little reason to doubt that it isthe result o f metasomatic pro cesses subsequen t to the dep o sition Of

the rocks . At the time o f metamorphism we can safely assume thatthey were do lomitic sedimen ts with a certain amoun t o f silica an d

alumin a of detrital o rigin . In the first p lace, the chemical chan gesin vo lved have been the elimin ation o f carbo n diox ide e in so far as

this has been p o ssible by reaction s,in vo lvin g the material ofdetrital

o rigin . In the absen ce o f such reaction s there has been a re

crystallization Of the , carbon ate min erals . In n o case has the simpledecarbon ation Of the magn esite mo lecule of do lomite taken place - to

p ericlase . It is to be in ferred that at the temperature prevailin gthe pressure was in excess of that n ecessary to effect any appreciabledi srup tion o f the do lomi te mo lecule, in the absen ce o f silica . o r

alumin a .

At a given pressure the temperature of decomp ositio n must beCo n siderably lower for do lomi te in the p resen ce of silica o r alumin a .

In these ro cks reactio n s invo lvin g the se con stituen ts have proceededto completion . The reaction s in vo lved brin g out very clearly thegreater chemical reactivity of magn esia as compared with lime ,a p o in t which is, o f course

,the basis o f Teall

’

s dedo lomi tizationp rin cip le . Domin an t lime - bearin g min erals, as the garn ets,vesuvian ite , wo llaston ite , etc .

,are con sp icuous by their absen ce ,

an d when they do app ear it is usually after all magn esia hasbeen satisfied . Fo r examp le , scapo lite an d bytown ite appear inassociated ro cks o rigin ally so impure that their metamo rphism is

accompan ied by comp lete elimin ation of carbon dioxide . These

4 58 G. E . Ti l leym jli etamorp hi sm of

lime - bearin g min erals are sufficien tly familiar in the metamorphismo f the calcareous limeston es .

The production o f fo rsterite from do lomite in vo lves thesimultan eous fo rmation of calcite

,as in deed do es the formation of all

the min erals invo lved In these ro cks,with the exception of a n on

alumin ous diop side . The equatio n s represen ting the production of

forsterite,ede n ite

,and diop side are shown below .

(1 ) 2 CaMg (00 9, Sic, Mg,SiO, 2 caco,

2 CO,do lomIte quartz forsterite calcite

(2 311 2 (CaMg 411 3 (310 2) A190

do lomiten CaMg8 2n 1 (CaCOs) 4n 3 (C0 2)CaMg2Al2 calciteedenite

(3) CaMg 2 SiO2CaMg (SiO3)2 2 CO,

‘

do lomite diopside

The ratio R

In the formation o f these mi n erals .

1 Con siderin g the case wherealumin a Is zero

,the production of forsterite

,tremo li te, and di opside

is conditio n ed by the value o f R,bein g 1

4 , 3 ,an d 1 for these min erals

respectively . Fo r the alumi n ous amphibo le eden ite R becomes2n 2

3n 2

mo lecules . In the presen ce of in creasin g silica, forsterite gives placeto first tremo li te

,an d then diopside, an d this order

‘

is on e of

decreasin g dedo lomitization . The formation o f an y on e of thesemin erals can be regarded as dependen t on the amoun t of silicapresen t (i . e . R) in thermal metamorphism

,o r the amoun t o f do lomite

in vo lved Within the sphere of diffusion of silica .

The presen ce Of alumi n a in the absen ce o f silica, p o ssibly as

bauxite leads '

to the formation o f sp in el as represen ted in theequation

CaMg A1203 MgAl2O, Ca

i

CO3

(30 2 .

spin elWhen silica is presen t the sp inel may accompany forsterite, an dthe close asso ciation of sp in el and forsterite as seen in the thinslices, —sp in el o ften presen t within the boun daries o f forsterite , o rabuttin g forsterite grain s, is eviden ce of co - crystallization in

accordan ce with the equation3CaMg —SIO2 —Al2 O3z Mg2SiO4+MgAl20 4+ 3CaCO3+

-3CO2 .

The value o f R is hereApparen tly when R exceeds this value, sp in el is less Often formed,

where 11 1S the ratio o f tremo lite mo lecules to Scharizer

with themo dified R values for these min erals .

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4 60 C. E . Ti l ley—Metamorp hi sm of

H'

and K,in the phlogop ite con stitution ,

we may represen t itsformatio n by the succeedin g equation9 CaMg H

2KA1

3 (Si0 4), 6 s o, 3

do lomite sericite quartz2 H

sMgSAl (Si0 4)3 9 CaCO3 9 CO.,

H2KMg3Al (Si0 4)3phlogop ite calcite

Hydrofiuo ric acid bein g regarded as an essen tial con stituen t ofphlogop ite, this will rep lace some of the water in the left - hand sideo f the equation , en terin g the phlogopite mo lecule as the un ivalen tradicle , MgF, isomorphous with H and K .

Whatever equation is adduced for the formation of phlogop ite,calcite is in evitably a by

- product o f the reaction , an d phlogop itemust therefore be added to .the group o f min erals which in duce bytheir formation dedo lomitization .

Apatite is doubtless derived by the recrystallization of origin alpho sphate substan ce in the sedimen t , po ssibly o f organ ic origin o r

o f detrital apatite o f pre - e 'xistin g rocks .

The apatite is observed to be p len tiful in tho se ro cks in whichphlogopite is mo st abundan t

,an d this asso ciation may have been

accen tuated through the agen cy o f fluorin e .The presen ce o f calcite as a con stituen t o f decomp o sed forsterite

grain s calls fo r some remark .

The chan ges which have op erated sin ce the formation o f forsteriteare firstly its rep lacemen t by serp en tin e, with or without theseparation o f magn etite, an d this may be represen ted by the

equation2Mg28i0 4 2 H

2O 00 2 H4Mg38i20 g MgCO3

The magn esium carbon ate is' either removed in so lution or is .

abso rbed in to the calcite or do lomite mo lecule durin g this chan ge .The chan ge has in many cases p ro ceeded further, however, an d inthe do lomites of Sleafo rd Bay serp en tin e has y ielded pseudomorphso f Opal an d calcite .

H4Mg38i20 9 3 00 2 2 SiO

'

23MgCO, 2 H

2O

opalHere

, again ,magn esite is released,

an d although this may be

p resen t in some o f the pseudomo rphs, y et in the maj ority its placeis taken by calcite .The o rigin o f the magn esite so characteristically associated withthe graphite schists in the vicin ity , an d developed in large massesIn the n orthern area

,an d essen tially o f secon dary origin ,

can probablybe traced in part to tho se reaction s which have ultimately resultedin the degradation of forsterite to opal an d calcite .The con version of the compact serp en tin e in to the fibrous

chry so tile asbestos is apparen tly a,recrystallization in situ,

under condition s o f n on - un iform p ressure , in which case the vein srepresen t p oten tial fractures, the elon gatio n o f the resultin gchryso tile fibres bein g n ormal to the direction o fmaximum pressure .

South Austra li an Do lomi tes . 461

It can be con sidered that the vein s have arisen as a con sequen ceo f the stress set up durin g the hydration by probably meteo ri c waterso f the o rigin al forsterite to compact serp en tin e . Po ten tial fracturesarisin g through this agen cy , the minute fibres o f heterogen eouso rien tation ,

are subj ect to an active un equal pressure in the vicin ityo i the p o in ts of p o ten tial fractures, such that in recrystallizin gso lution takes place in tho se fibres orien ted acro ss the direction o f

min imum pressure, on ly to be redepo sited o n tho se fibres whoseelon gation is parallel to the directio n o f min imum pressure

,un iform

cro ss fibre vein s thus arisin g .

The re lation ship of the «n ew—formed calcite to fo rsterite .

Teall,

1 first p o in ted out that forsterite formed durin gmetamorphismwas in timately associated with the n ew—formed calcite an d usually indirect con tact . It has already been remarked that the same featuresare to be seen in the rocks un der discussion , an d in man y case s theassociation is very strikin g . The fo rsterite may be who lly embeddedin calcite or partly surroun ded by an aureo le of thismin eral . ’

Cro ok 2has po in ted out that In man y examples of fo rsterite marble studiedby him the s ilicate is separated from the calcite by a thin rin go f do lomi te . No cases o f this n ature have been foun d in thesemarbles . The di stribution o f do lomite , calcite , an d forsterite ' iso ften best seen by stain in g a thick slice of the ro ck an d then coverin gwi th a cover-

glass . The individual grain s can then be easily made outwith a len s .

Do l omi t e ben d

Calcite . Forsterite .

FIG . 2 .—Diagrammatic sketch o f portion o f a flat surface of do lom ite .

A do lomite from the Hutchison area treated in this way was seento con sist of ban ds of un stain ed do lomite

,altern atin g with a ban d in

which the forsterite grain s are con cen trated, an d o f calcite (se e Fig .

This app ears to afford eviden ce that we have here to dea lwith ban ds o f origin ally di fferin g compo sition ,

viz . do lomite ban dsfree from impurities an d c on tain in g detrital silica respectively .

As a result o f the formation o f forsterite, the siliceous ban d isdedo lomi tized

,the n ewly formed forsterite

. bein g surroun ded byrecrystallized calcite derived from the .reaction . These examplesserve to con firm the vi ew that the radius o f diffusion in thermalmetamorphism is con fin ed within comparatively n arrow limits .

J . J . H. Teal l, GEOL . MAG . ,

1903, p p . 513—14 .

2 T . Cro ok, GEOL .MAG . , 19 1 1 , p p . 339—45 .

4 62 Metamorp hi sm of .S0u th Austra l ian Do lom i tes .

The o ccurren ce of small grain s of sp in el embedded in do lomitewithout proximi ty to calcite may p erhap s be exp lain ed by assumin gthat the n ew- formed

‘,calcite is comp letely absorbed within the

do lomite mo lecule —the eviden ce p o in tin g to ' the view that there isa limi ted mi scibility o f these two min erals, con formin g , presumably ,to Typ e 5 of Reozebo om

’

s classificatio n .

1

The criteria for the distin ction of dolomite'

and calcite .

The three criteria which are available fo r the distin ctio n o f

do lomite an d calcite in_

some o f _ these rocks have already beenmen tion ed . Of these the mo st impo rtan t is the distin ction basedon the turbidity o f the n ew formed calcite . The do lomite, on theo ther han d, is remarkable for its clarity an d limp id character . Theturbidity o f the calcite

,when examin ed un der the high power, is

seen to be related to the presen ce o f minute in clusion s o f two typ es ,o n e co lourless to grey ish particles o f high refractive in dex, an d certainopaque particles of un certain n ature

, but perhaps carbon aceous .

However this may be , it is eviden t that the turbidi ty is of gen eralo ccurren ce . Some o f the particles may be o f detrital origin ,

an

their presen ce in calcite an d absen ce in do lomite may stan d relatedto the positio n of these min erals in the crystalloblastic series .

Do lomite is the stron germin eral , an d is usually idioblastic towardscalcite . Durin g recrystallization foreign materi al may be discharged,o n ly to be absorbed within the weaker and more y ieldin g calcite .All these criteria are to be foun d in the literature on the co n

stitution of the crystallin e limeston es , but the data are somewhatcon fusin g . The criteria as n oticed here are somewhat similar totho se advan ced by Lacro ix 2 for the limeston es o f Cey lon ,

an d

later by Fermor3 for _ the crystallin e limeston es of the Chhin dwara

district,In dia .

Some of them are di ametrically opp o sed to the criteria summarizedby Ren ard,

4and reprin ted in the textbo oks . Fermor would exp lain

his own examp les (apparen tly as abn ormal) , an d presumably tho seo f Lacro ix, by the suggestion that the carbon ates have been formeddirect from silicates

,and n o t by the alteration of pre

- existin gcalcite . Whilst it is true that the carbon ates in the rocks un derdiscussion have been recrystallized, there i s n ot the slightest eviden cethat this silicate derivation obtain s . They are recrystallizationproducts un der the in fluen ce of thermal metamo rphism,

the maj orityof the calcite bein g released from origin al do lomite mo lecules

(To be con tin ued . )

1 R . C Wal lace , Comp te Ren du XIIe se ssion Con gre s Géo logique In ter

n atl o n al , Can ada, 19 13, p p . 882—3.

2 M. Lacro ix, Rec. Ge o l. Sll l V . In dia ,vo l . xxiv ,

189 1 , p t . 111 p p . 19 1 .—2 .

3 L . L . Fe rmo r ibid. ,vo l . xxxiii , 1906, p t. ii i , p p . 195—7 .

4 A . F Re n ard, Bul l .'

Acad Royale de Be lgique , vol . x lvu . 1879 , No . 5,

p . 557 .

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4 64 H..A . Baker— Loose A r en aceous Sedimen ts .

been do n e , the writer could discover n o trustworthy case in whichthe wo rk had been accompan ied by accurate determin atio n o f themean diameter o f the material used in the exp erimen ts . Dr . JohnS. Owen s,1 however, made observation s in the case o f phen omen ao f typ e (b) above , and it was foun d p o ssIble to make use o f his

results . He carried out exp erimen ts on the tran sp ortin g powero f sea - curren ts

,usin g flin t p ebbles ran gin g in diameter from half

an - in ch to Six in ches . The pebbles were ro lled by the curren tso ver a san d surface . AS a result o f his experimen ts

,Owen s arrived

at the formula45V2

W— 64

where d diameter of pebble in in chesW weight of a cubic fo o t o f pebble material in p o un ds,V velo city , in fe et/sec . of curren t just competen t to

tran spo rt the p ebble .Nowit seems legitimate to argue that, where we have flin t pebbles

scattered throughout a bed o f san d we may fairly assume that thesame con dition s were required for the dep o sition o f the p ebbles as

fo r the sand . The o bservatio n s of Owen s , Vaughan Corn ish , Gilbert ,an d o thers

,have

,however, shown that when aren aceous material

is under tran sp ort by curren ts of lower velo city than 2 5 feet p ersecond it invariably moves forward i n the form o f sand- ripp les, an dthe ripp led surface always arrests the movemen t of p ebbles un lessthe velo city o f the curren t is greatly in excess of that required tomove them . Accordin g to the formula given by Owen s , at a Speed o f2 5 feet p er second,

a curren t would be able to tran spo rt fli n t p ebblesup to 2 85 in ches in diameter . Therefo re,where we have a bed of

san d with flin t pebbles scattered fairly un ifo rmly through it, andthese pebbles clearly average less than 2 85 in ches In diameter, wemay assume that the curren t which tran sp orted the material to itsp resen t restin g -

p lace , an d from which it was depo sited,was at least

as fast as that required to tran sp ort p ebbles o f the size seen,sin ce

the arrest an d burial o f these p ebbles was probably brought aboutin con sequen ce of the formation of san d~ripples o n the bed . We

may assume further, that the velo city of the curren t was n ot greatlyin excess o f that required to move pebbles o f the Size seen ,

for, had

it been so,the sand- ripp les would n o t have checked the p ebbles in

their career .

The Than et Beds con tain n o flin t pebbles, but after some searchthe writer selected a sectio n in Blackheath Pebble Beds in whichn umerous flin t p ebbles, averagin g less than 28 5 in ches in diameter,but o f n o table un iformity o f size

,were even ly distributed through .

out a bed of san d . A samp le was taken con tain in g bo th p ebbles an dsand . On e hundred represen tative pebbles were selected an d their

1 Owe n s , Exp erimen ts on the Tran sportin g Power o f Sea Curren ts

Ge og . Journ . , April , 1908 , pp . 415

H . A . Baker— Loose A r en aceou s Sedimen ts . 465

total vo lume foun d by disp lacemen t . The diameter of the average;p ebble , assumed spherical , was then calculated . The result was2 197 cm . The average Sp ecific gravity o f the flin t was thendetermin ed an d the weight in . lb . o f a cubic fo ot ~of flin tcalculated These figures were then applied to Owen s’fo rmula thus

0 2197 X 39 -3708

g ivin g V 137 ft ./sec .

This value may be taken as themi n imum sp eed (probably n o t muchbelow the true speed) o f the curren t from which the sand asso ciatedwith the p ebbles was dep osited . A min ute mechan ical an alysis o fthe san d was n ext made

,the elutriatio n - curve drawn

,and the

Equivalen t Grade figure determin edwith great precisionThe san d proved, fortun ately ,

to give a curve of remarkables imilarity to a Than et San d o f in termediate typ e , with a fairly highGradin g

‘

Factor . The Equivalen t Grade o f the sand was taken as

the represen tative diameter o f the material . It was a_

figure onwhich much relian ce could be placed, in view o f the high Gradin gFactor .

“ Then,by substitution in the formula

a' M7

C

2

the value to be assign ed to . the factor k (for tran sport of sand in

bulk) was ascertain ed, thus- 102 k x (1

d bein g taken in mm . an d V in feet p er secon d .

Hen ce In : 0 54 .

The value of h, as obtain ed directly from Owen s’ formula (bysubstitutin g In it the weight In lb . o f a cubic fo o t of quartz) , is o f

much larger order than that o btain ed above, so that velo citieslculated by mean s o f it are much less than tho se obtain ed whentakin g the value in dicated above . It has lon g been kn own ,

however,that an aggregate requires higher velo city to move it than do es a

S in gle obj ect . T . E . Blackwell demon strated this in 1857, an d Owen shimself n o ted that the velocities required to move sand -

grain s inthe mass were several times greater than the velo cities as calculatedfrom his formula

,o n substitutin g in it the diameter of the

in dividual grain s . In View of the use to which the aboveresult was to be put, the writer thought it well to checkthe formula . by repeatin g the exp erimen t with a fresh sampleo f san d con tain in g flin t p ebbles obtain ed from an o ther area .

A seco n d samp le was taken ,this time from the lower part o f

the Woolwich an d Readin g Beds, at a sp o t man y miles distan tfrom the p lace whence the first samp le had been o btain ed . Theresult was remarkable . The hun dred represen tative p ebbles gavean average diameter very n ear that obtain ed in the first experimen t

VOL . LVII .—NO . x .

'

30

4 66 . H. A . Baker— Loose A r en aceous Sedimen ts .

om . as compared with 2 197 an d the Equivalen t Gradeof the associated san d Simi larly gave a figure extraordin arily n earthat obtain ed in the case of the first san d mm . as

'

comparedwith‘

102 If this be n ot a S in gular co in ciden ce it must in dicatea sign ificant con n exion between the size o f the p ebbles in a san dybed an d the Equivalen t Grade Of the san d itself . With regard tothe co n siderable variation o ften to be seen in the sizes Of p ebblesin cluded in a san dy bed, it should _

be born e in min d that the u eightof ston e which a curren t can move varies as the sixth power of thevelo city ,

an d that therefore a Slight in crease in velo citymay produceeffects out o f all propo rtio n to what would be exp ected . The

determin ation Of h from the data o f the seco n d exp erimen tgave '

056 as compared with ‘

054, the value obtain ed previously ,an d accordin gly '

055, the mean o f these two results, was taken .

Hen ce,fo r the case of the tran sp ort, in bulk, of aren aceous material

similar to that of which the Lower Lon don Tertiary strata of the .

southern side of the Lon don Basin are comp o sed,the formula

d - 055

where d is the Equivalen t Grade o f the material in mm . an d V,

is the velo city in fe et/se c . just comp eten t to tran sp o rt the material,

is put forward with a certain amoun t of con fiden ce .LOWER THANET BEDS .

Beddin gton . Charlto n . Swan ley . East Ken t.

Equiva len tGradeo f material

in mm .

UPPER THANET BEDS .

Charlton . Gre e n hith e . Pe gwe l l Bay .

1

Equival en tGrade

o f material 042

in mm .fo r highe st Th an e t

Be ds se e n .

1'The h ighe st Than e t Beds se en at Pegwe l l Bay real ly repre sen t a fairly low

l eve l in the depo sit, but the se data are in cluded here because they we re used

in . the diagram (Fig .

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REVIEWS.

SPECIAL,REPORTS ON THE MINERAL RESOURCES OF GREAT BRITA IN .

Vo l . XI : THE IRON ORES OF SCOTLAND . By M. MACGREGOR,

G. W. LEE, G. V . WILSON, T . ROBERTSON , an d J . S. FLETT .

Mem . Geo l . Survey . pp . vii 240 , with 18 text - figur_es .

Edin burgh, 1920 . Price 103. n et .

HE fourth vo lume of this valuable series to be devo ted to“ ironores gives a very comp lete and comprehen sive accoun t of tho se

o f Sco tland, bo th of actual and po ten tial value . The first section ,

o f a historical n ature, gives an in terestin g ske tch Of the early an d

very remarkable attemp ts at the smeltin g of iron - ores from En glandand elsewhere by mean s Of charcoal derived from the forests of theHighlan ds, which seem to have had a real existen ce in those days ,o utside of the imagin atio n s o f En glish So cialist propagandists .

Thus in the eighteen th cen tury furn aces were erected for the smeltin go f iron in such extraordin ary places as Bonawe

, Glenkin glas,Invergarry , Strathspey ,

and Lo ch Maree,the ore bein g brought

from the coalfie lds of Cen tral Sco tlan d and from Cumberland .

Naturally this industry did n ot en j oy a lon g life, but stran gely en oughthe Lorn e Furn ace at Bon awe seems to have strugg led o n

spasmodically till 1876 .

Effective iron - min in g in Scotland may be s aid to have begun in1760

,when the Carron Iro nwo rks started to smelt clayban d ores

“With coal . So on after this great developmen t began in theCarbon iferous bedded ores, givin g rise to an in dustry o f first- rateimportan ce . The greater p art Of this memo ir is n aturally taken upby a detailed descrip tion o f the o ccurren ces Of this type, which arefound over a large area in the cen tral parts of Sco tland, ran gin g within tervals from Ayrshire to Fife , the greatest developmen ts bein g In

Lan arkshire and the adjo in in g coun ties,here called the Cen tral

Coalfield . This section , can no t fail to be Of the greatest value toSco ttish min e - own ers and geo logists . Careful and apparen tlyconservative estimates are made o f probable an d p o ssible reserves .

The n on - Sco ttish geo logist will, howe ver, undoubtedly turn withgreater in terest to the accoun ts here g iven o f some o f the S ide - Shows,such as the Jurassic o res of Raasay an d the remarkable vein s of

the Orkn eys and Shetlan ds . The Raasay bed,which is n ow kn own

to' belon g to the Upp er Lias, though at first co n sidered to be theequivalen t of the ClevelandMain Seam ,

has actually been a producer,but it is doubtful ,

whether it could be made to pay un der p eaceco nditio n s

,owin g to high cost o f tran sp o rt . An an alysis o f an

average sp ecimen o f the raw ston e , quo ted in this memo ir, gives25 2 p er cen t o f metallic iron with 2 3 p er cen t o f phosphoric acid,

while Dr . Hatch states that it averages about 23 p er cen t , wi thO 9 p er cen t phosphorus . The sto n e i s therefore o f low grade .We are glad to n o te that in this memo ir a glossary is given of theextraordin ary lan guage in which the Scottish min in g geo logists

Revi ews— In ver tebrate Pa lce on to logy .

’

469

have effectively con cealed their thoughts from the Southern er ino ther p ublicatio n s dealin g with the coalfie lds of the same areas .

R. H. R .

INVERTEBRATE PALEONTOLOGY AN INTRODUCTION To THE STUDY

OF FOSSILS . By H. L . HAWKINS,M.Sc .

, F . .G S pp . xix ,226, with 16 plates . Lon don : Methuen Co . 1920 . Price63. . 6d. n et .

HIS bo ok is apparen tly in ten ded for those who are begin n in gthe study o f fo ssils,

_

an d also for studen ts who have alreadysome kn owledge of palaeo n to logy . The first four chap ters deal wi ththe scop e and aim o f palaeon to logy ; the n ature

, o ccurren ce ,preservation ,

co llectin g , an d preparation o f fossils ; an d wi thstratigraphical and physiographical palaeon to logy . These chaptersare written in a clear an d in terestin g sty le , an d with theaccompan y in g illustration

-

S should prove attractive to begin n ers .

The secon d part of the bo ok “is design ed to give an epitome of

the sequen ce o f evo lution as it has been un fo lded in geo logicaltime This part is divided in to (1 ) Pre - Cambrian Faun as, (2)Lower Palae o zo ic Faun as

, (3) Upp er Palaeo zo ic Faun as, (4) Meso zo icFaun as, (5) Caino ic Faun as . By takin g these relatively lon gtime - division s the author is able to give a more con tinuous accoun to f the gen eral evo lution ary chan ges in the various group s of fossilsthan is p o ssible when the life o f each geo logical system is con sidered.

separately . But,as the author p o in ts out, this part o f the bo ok will

be in telligible on ly to tho se readers who have some con siderablekn owledge o f morpho logical an d systematic palaeon to logy an d thesame remark applies to the precedin g chap ter o n Bio logicalPalaeon to logy in which an attemp t has been made to

'

give agen eral accoun t of the broad outlin es of phy logen etic evo lutionThe autho r here deals with the more modern lin es of research inthe Palaeon to logy o f the Invertebrata, in a way which shouldarouse the in terest Of students . We thin k it’ would have been

,

an

advan tage if this chapter had been expan ded an d fully i llustrated,sin ce this asp ect of Palaeon to logy has been less frequen tly dealt wi thin textbooks than the subj ects o f the o ther chapters .

REPORTS AND PROCEEDINGS.

British A sso ciatio n , Cardiff, 1920 .

SECTION C.

— GEOLOGY .

1 . Presiden tial address by Dr . F . A . BATHER,F.R .S. (se e p .

Pro fessor AfHUBERT Cox : Address on the Geo logy of theCardiff District .3. Dr . J . W. EVANS

,F.R .S. The Origin Of the Alkali Ign eous

Ro cks .

The se ro cks , distin guished by un usual ly high p rop ortion of alkal ie s,re lative ly to alumin a an d l ime , o ccur main ly where the crust of the earth

470 Rep orts (QPr oceedi n gs— Br i ti sh Associati on .

is thick,the he at -

gradie n t low ,an d there has be en n o fo ldin g Sin ce remote

time s . Magmas ap p e ar to have re ached surface by fault fissure s fromgreat dep ths whe re high p re ssure s are asso ciated with comp arative ly lowtemp erature s . Cry stal lization pro ce edin g un der such circumstan ce s,

the re would be an early formatio n o fmin e ralswith smal l mol e cular vo lume s ,

g arn e t, ky an ite , ep idote , an d zo isite ,min e rals rich in l ime an d alumin a .

'

Zo isite may be regarded as high p re ssure rep re se n tative of an o rthite , but

there is n o corre sp on din g rep re sen tative o f albite or o rthoclase . Con

sequen tly we should e xp e ct a re sidual magma e xcep tion al ly rich in alkal ie swhich would furn ish material n ece ssary for fo rmation Of a lkal i ro cks .

4 , Reports Of Research Committees .

5 . Jo in tmeetin g with Se ctio n SD an dK . Discussion : Men del isman d Palaeon to logy : The Factorial In terpretation o f GradualChan ges, esp ecially when New Characters app ear late in theIndividual Life - cycle . Dr . F . A . BATHER,

F .R .S.

The que stion p o sed . Can characters be regarded as in dep en den t, i . e .

as man ife station s of in de p e n de n t factors in the germ Do e s evo lution

take p lace so le ly by addition o r lo ss of such factors Is there n ot also‘

a gradual modification of the body ,re sultin g in a con tin uous tran sition

Palaeon to log ists fin d such tran sition to be the rule in those case s where theg e o log ical reco rd is sufficien tly comp lete . (See P re side n t

’

s Addre ss ,Se ction C, he adin g “

Co n tin uity in Deve lopme n t Palaeon to l og ists

supp ort the the ory of re cap itulation ,an d be l ieve that in man y case s

gradual modification of the adult an d sen ile body is,in the course

o f race - history , p ushed back to e arl ier growth stage s . (Se e Pre siden t’

s

Addre ss, Se ction C,headin g “

Recap itulation Can such case s be

e xp lain ed by in dep en de n t factors in the germ Do e s n ot thathyp othe sis in vo lve ,first, an alteration of the ge rm through chan ge in the

body , secon dly the determin ation of that g ermin al chan ge in a directionharmon ious with bodily~chan geDr . R. RUGGLES GATES

Accordin g to mutation ist hyp othe sis, g e rmin al characters arise as

alteration s o f Sin gle e leme n ts of the g erm p lasm . This con cep tion

avo ids - the difficulties in vo lved in con siderin g the chan ge as due to

the l oss o r addition o f a factor . It recogn ize s o n the on e han d the

so lidarity Of the g e rm p lasm as a who le , an d o n the o ther the

i n dep en den t o rig in .o i variation s in ‘i ts seve ral p arts . Such variation sare termed kary ogen etic, Sin ce they ap p are n tly arise in the n ucle i

an d are p erp etuated by mio tic divisi’

on . Mutation s of this n ature

are almo st un iversal amon gst wild p lan ts an d an imals , an d some of

them are SO smal l that for g en eral purp o se s they are p ractical lycon tin uous . They differ from the Darwin ian con cep tion o f con tin uous

variation,howeve r, in that (i ) they do n o t arise in an y regular order, (ii )

they are in herited as se p arate un its . But re cap itulation is an almo st

equally wide spre ad phen ome n on in an imals , an d to a l e ss e xten t in p lan ts .

The recap itulation i n an imal embry o s; an d in such fo ssil group s as the

Ammon ite s,imp lie s the addition o f termin al stage s to the deve lopme n t

Of the o rgan ism . From the stan dp o in t of organ ic structure this p ro ce ssis clearly differen t from a mutation by which the n uclear un it is modifiedthroughout the organ ism . Re cap itulato ry characters thus fal l in to '

two

group s (i ) embry on ic , which ap p ear alway s to imp ly adaptation of the

o rgan ism to diffe ren t con dition s, an d are be st exp lain ed by the n e o

Lamarckian p rin cip le ; (ii ) o rthogen etic, which app ear late in the l ife

cy cle but are g e rmin al in o rig in an d n on - adap tion al .

Professor J . E . DUERDEN :'Mendelism ; Palaeon to logy ;

Evo lution .

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4 72 Rep orts ct Proceedi n g s Br i ti sh A ssociati on .

at various ho rizon s , and usual ly con tain s n o Ammon ite s , but corre lation

can be made by mean s of sp e cie s o f Ostrea an d Cryp hea. In the n umerous

e xp osure s n ear Radstock man y n on - sequen ce s can be lo cated,an d map s

showin g the moveme n t o f in fra - Liassic fo lds have be e n p rep ared .

9 . Dr“

. J . K . CHARLESWORTH : The Glaciation o f the NorthWest o f Ireland .

The maj or p art o f the reg ion in ve stigated,in cludin g the Don egal

Highlan ds an d the Sp errin Moun tain s, was n ever in vaded by the Scottishice as curren tly sup p o sed, but the Don e gal moun tain s , in p articular the

Barn e smore Hil ls, fo rmed a mo st p owerful ce n tre o f radiation when ceice streamed we stwards to the Atlan tic an d e astwards o ver the .Sp e-rrin

Moun tain s to Co okstown an d bey on d . In a ss

-outh e aste rly direction the

ice passed obl ique ly acro ss the Cloghe r Valley in Sl ieve Be agh to the

Ce n tral Plain o f Ire lan d , where was0

lo cated the cen tral axis of Hul lan d Kilroe . This axis o f disp ersal e xisted at n o p eriod _o f the g laciation .

10 . Mr . L . DUDLEY STAMP : On Cycles of Sedimen tation in theEocen e Strata of the An glo - Fren ch—Belgian Basin .

The Eo cen e dep o sits o f the gre at An glo-Fran co t- Be lg ian Basin can be

group ed n atural ly in to a serie s o f cycle s o f sedime n tation the Mon tian ,

Lan den ian , Yp re sian , Lute tian , Ledian , an d Barto n ian . Each cy cle

commen ce s with a marin e in vasion an d p asse s from marin e to e stuarin e

an d con tin en tal con dition s . In En g lan d the chan ge s are clo se ly con ne cted

with the gen tle , in termitten t up rise o f the Weald .

11 . Dr. J . W. EVANS, The Geo logical Structure o f

North Devon .

In e arly Pe rmian time s the De von ian an d Carbo n ife rous we re thrown

by p re ssure from the south in to overfo lds, with overthrust faults

A subsequen t re laxation of p re ssure re sulted in a s l ip back on the same

fault -

p lan e s . The re we re also oblique tear - faults strikin g betwe en n orthan d we st . A moun tain reg io n then slop ed southward from the We l sh

Coast to Mid - Devon an d much material was tran sp orted in that dire ction .

In the Triassic p eriod,however ,

the Pa lae o zo ic had , as a who le , its p re se n t.

con tours, in cludin g the gre at:Glaston bury an d Bristo l Chan n e l dep re ssion

de scen din g to the we st, an d its subsidiary valley s*

'

stil l p artly fil led withMe so zo ic dep o sits . In Tertiary time s there was ren ewed p re ssure from

the south . This met with l e ss re sistan ce in the we st, an d the re wasco n seque n tly a re lative ly forward an d downward moveme n t on that Side

alon g the o ld te ar faul ts an d p o ssibly n ew fractures with the same g en eral

dire ction . In Pl io cen e time s the lan d was more submerged than n ow

an d the subseque n t emerge n ce se ems to have con tin ued in mo st p lace s till

a comparative ly re cen t date .

12 . Professor W. L . BRAGG : Crystal Structure .The in ve stigation in to cry stal structure , which has be en made feasible

by the discove ry o f the diffraction of X - ray s by cry stals ,has l ed to a

de te rmin ation of the p recise p o sition s o f the atoms in a n umber of the

simp ler cry stall in e forms . Re ce n t the orie s of atomic structure such as

tho se p ut forward by Born an d Lan de Deby e , Lewis , an d Lan gmuir,are

large ly based o n the arran g emen t o f the atoms‘

in cry stall in e so lids ,

sin ce this arran g emen t affords an in sight in to the n ature of the force s

actin g betwe e n the atoms . In such comp oun ds as sodium chl oride ,it

is p rob

bable that the atoms e xist as ion s o f sodium an d chlorin e , an d thatthe cry stal 1s he ld togethe r by the e lectro static attraction s of the se ion sthus accoun tin g for the fact that there is n o group in g o f the atoms

mo le cule s i n the so lid . In othe r comp oun ds , such as tho se of two

e le ctron egative e l emen ts, the mo lecular arran g emen t p e rsists in the so l id

state an d the chemical combin ation ap p e ars to be . o f a differen t typ e

P r esidentia l Address to Secti o n C.

from that of sodium chlo ride . A con sideration (if the distan ce s betwe e nthe atomic Cen tre s in '

cry stals supp orts the con cep tion of the two typ e s o f

chemical combin ation .

'

13. Mr . DAVID DAVIES : P-alaeon to lOgy o f the Westphalianan d lower part of the Staffordian Series o f the Coal - measures as

found at Clydach Vale an d Gilfach Goch, East Glamorgan .

Re corded p lan ts ; she l ls ; two in se cts an d o n e fish scale .

Plan ts y ie lded 154 sp e cie s, she l ls Six Sp e cie s, in se cts two sp ecie s , fish scal e

o n e ; fo rty- five of the se are n ew to SouthWale s an d seve n n ew to Britain .

Eco l ogy of ten horizon s : Equisetale s p redomin ate in four, Fil icale s an d

Pterido sp erms in'

thre e,Ly cop ods .ih two ,

an d Cordaitale s in o n e horizon .

When Ly cop ods p redominate ,Fern an d Fern - l ike p lan ts are weak,“ an d

vice versa . 37 p e r cen t pl an ts are common to both s e rie s ; 31 p e r cen t

distin ctly Staffordian 32 p er ce n t distin ctly We stphal ian . The Pen n an t

San dston e p roduced smo oth roun d coal p ebbl e s , givin g eviden ce of a

ge o logical bre ak . A sign ifican t feature is the ap p e aran ce Of n ew sp ecie s

at this p e riod .

14 . Mr. D . C. EVANS The Ordovician Of Carmarthen .

This p ap e r de alt with the stratigraphical succe ssion an d tecton ic

structure s of the Ordovician ro cks of Carmarthe n shire

PRESIDENTIAL ADDRESS To SECTION C (GEOLOGY ) .

Owin g to unusual .pre ssure e on our Space We are un able this y earto reprin t the Presiden t’s address in full . For the fo llowin gabstract an d a ppreciation we are in debted to Dr . F. H. A .

Marshall,F.R .S.

Dr . Bather ’s p re side n tial addre ss deals with the fun damen talsp rin cip l e s

of Palaeon to logy . He begin s by p o in tin g out that it is the time - concep t

which characterize s the subj e ct an d raise s it above the mere de scription“

of extin ct assemblag e s of an imals an d p lan ts, an d he p ro ce eds to con sider

the e ffect o f this con cep t on the p rin cip le s o f classification an d on the

ideas o f re lation ship . In the l ight of p al aeon to l og ical study defin ition s o f

group s. o f an imals or p lan ts can n o l on g er be pure ly de scrip tive ; theymust take accoun t of an ce stry an d succe ssion in time . AS Dr . Bathere xpre sse s it : The o ld form Of diagn o sis was p er gen us et difieren tiam .

The n ew form in p er p roaoum etmodification em. It has n o t be e n un usual

to fal l in to the e rror that the app aren t succe ssion through a serie s of strata

o f Similarf o rms of l if e imp l ie s de scen t, an d Huxley ,in his scheme Of equin e

evo lution,regarded Palaeotherium as be in g in the l in e of direct an cestry of

the mo de rn horse . Howeve r, this sp e cie s ,an d the late rArchitherium,

have

be e n shown by Profe ssor Osborn an d his co - write rs to be l on g to side - lin e s o f

de scen t . Occasion al ly an ap pare n t succe ssio n is due to immigration Of

a distan t re lative from an other regio n in the man n er sup p o sed by Cuvie r

in se ekin g to account fo r the re n ewal of l ife whe n . an earlier faun a had

disapp eared . Dr . Bather g o e s o n to co n sider the e viden ce Of de scen t

afforded by p alaeon to lOgical in stan ce s of the law o f recap itulation , whichis SO we l l i llustrated by the ammon ite s . In the n e xt se ction o f the addre ss

he p o in ts out that the l in e up on l in e method is the on ly abso lute lysafe way of advan ce in Palaeon to logy ,

for mutation must be affiliated withmutation an d sp e cie s with sp e cie s ; the in ve stigator must work his wayback

, l iterally in ch by in ch through a Sin gl e smal l group of strata ,

”

if he

wan ts to be sure o f his con clusion s about l in e s of evo lution . Con cern in gthe que stion as to whe ther de scen t had taken p lace by con tin uous o r

discon tinuous variatio n it is shown that con trary t o what might have be e ne xp ected , p alaeon to logical op in ion is emphatical ly in favour of the fo rme r

474 Corresp on den ce— C. Caru s Wi lson .

V iew . With the sp ecie s of the sea - urchi n M icraster the chan g e s un derg on ein the course o f age swe re apparen tly gradual in all the di fferen t characte rs

,

an d man y o ther in stan ce s of con tin uous evo lution might be g ive n . After

brief referen ce s to the con cepts of seriatio n or the dire ction o f chan ge ,

Dr . Bather p ro ce eds to discuss the que stio n o f p i e- determin ation , which

man y p alaeon to log ists se em to have accep ted . The p rin cip le is thuse xpre ssed A race o n ce started on a certain course will p ersist in thatcourse ; n o matte r how con dition s may chan ge , n o matter how hurtfulto th e in dividual its own chan ge s may be , p rogre ssive or re trogre ssive ,

up hill an d down hill , straight as a Roman road it wil l g o o n to thatap p o in ted en d .

”

The p rin ciple is al lied to Drie sch s con cep t of e n te le chyin on tog en etic deve lopmen t, an d the que stion o f its val idity se ems to be

p art o f the wide r p roblem as to whether te le o log ical categorie s have an y

p lace in bio logical thought, a que stion which is an swered in the n egative

by al l men of scien ce ,e xcep tin g the smal l min ority who adopt the attitude

o f Dr . J . S . Haldan e . Dr. Bathe r n e xt discusse s adap tive evo lution al

con ve rgen ce an d p asse s o n to con sider Do l lo’

s so - cal led law o f

irreversible evo lution . He doe s we l l to in sist that this law is a statemen t

of Observed fact an d , un derstood rightly ,n e ed

“

n ot imp ly an y in heren tp rin cip l e affirm i n g the imp o ssibl lity of reve rsal . The n e xt se ction s

deal with the study o f habitat an d the temp o Of evo lution which ,it is Shown ,

is variable , dep en din g on chan ge s in the oute r con dition s .

This is il lustrated by the comp arative study of the deve lopmen t of whale s ,Sire n ian s, an d horse s durin g the Tertiary p e riod,

the rate of evo lution of

the se thre e group s vary in g with that o f chan ge s in the n ature of the fo od .

Thus the siren ian s un derwen t a slow chan ge be cause they retain ed thehabit of fe edin g on soft water -

p lan ts , the horse s deve lop ed mo re rap idlyin co rre lation with the ir takin g to the p lain s an d becomin g e ate rs of grain ,

while‘the whale s , though at first the ir deve l opme n t was slow, from the

Ol igo ce n e onwards chan g ed with e xtraordin ary ce lerity as they adopted

an d dive rsified n ew habits o f fe edin g an d l ivin g . In re fe rrin g to the

rhy thm of l ife Dr . Bather co n clude s that the phen ome n on mustrefle ct the gre at rhy thmic wave s that have up l ifted the moun tain s an d

lowered the de ep s, as we l l as the smal ler wave s an d rip p le s that havefrom time to time dive rsified the face o f the earth . The addre ss is throughout bo th sugg e stive an d s timulatin g 1t con clude s on a n ote o f san guin e

an ticipatio n fo r the future .

CORRESPONDENCE.

FLINT PROBLEMS .

SIR,—All efforts to so lve the problems of flin t formation are likely

to be un successful un less we marshal all kn own facts and dealw iththem seriatim . At presen t I doubt if it is po ssible to give even a

satisfactory defin ition o f fli n tMan y y ears ago

' I foun d flin t at Margate and Studland Bay ,which is clearly silicified chalk . In p laces silicification has n ot

been comp leted, an d these softer parts have been removed, leavin gcavities

.Near Corfe I came acro ss n odules in the chalk which ,

with the excep tio n Of a thin extern al crust of fli n t , are en tirelycomp o sed o f soft, white cryp to crystallin e Silica . There are flin tp ebbles at Boscombe an d Southbourn e - On - Sea that are comp osedpartly of the same cryp to crystall in e silica 1 and partly o f chalcedon ic

1 Nature,May 1 , 1890 .

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4 76 Obituar y Wheelton Hi n d.

OBITUARY.

Whe e lto n Hin d, M .D B.S. , F.R.C .S F.G .S.

BORN 1860 . DIED JUNE 2 1 , 1920 .

DR . WHEELTON HIND was born at Roxeth,n ear Harrow,

in 1860 ,and died after a comparatively short il ln ess at Ashley ,

n ear Stokeoh - Tren t

,o n Jun e 21 of this y ear . He received his medical train in g

at Guy’

s‘

Hospital and Lon don Un iversity , where he graduatedM.D .

,an d also gain ed the Fellowship o f the Royal Co llege o f

Surgeon s . In 1884 he began practice in Stoke - on - Tren t,an d durin g

the fo llowin g thirty y ears established a reputation as on e of the

foremo st surgeon s in the district, bein g at the time o f his deaththe sen io r member of the surgical staff o f the North StaffordshireIn firmary .

So far as research work is con cern ed,Hind’

s in terest in geo logyp ractically dates from his arrival in Stoke , forvery shortly thereafterhe made the first of ‘

a lon g series of co n tribution s on lo cal geo logyto the Tran sactio n s o f the North Staflordshire Naturalists’ FieldClub . Amon gst his earliest papers was on e on the geo logy of Suffo lk,which was in corp o rated in his father’s bo ok o n the flora o f thatcoun ty . As might be exp ected from his lo cation in a coal - min in gdistrict, most o f his wo rk related to the s tratigraphy an d

p alaeon to logy of the Carbon iferous ro cks,esp ecially of the lower

members o f that series . In an en deavour to find some key to thesuccession of these strata he so on extended his investigation sto the correspon din g rocks of Derbyshire , Lan cashire, an d Yorkshire

,where he co llaborated with Mr . J . A . Howe in a detailed

examinatio n o f the Lower Carbo n iferous sequen ce of the Pen dleHill area . As a result o f this wo rk the hitherto recogn izedclassification o f this series underwen t con siderable modificationby the recogn ition of the Pendleside Series o f shales an d thinlimeston es

,with a characteristic faun a

, as a group in termediatebetween the Carbon iferous Limeston e and the Millstone Grit an d .

differin g essen tially ,bo th in litho logy an d fo ssils

,

“

from the YoredaleSeries . The developmen t o f this series in Derby shire an d Staflordshire was recogn ized, and it was also traced to the Isle o f Man an d

Irelan d .

The basis o f Hin d’

s stratigraphical ‘work was the attemp t todiscover a series o f life - zon es by mean s of which the Carboni ferousro cks could be subdivided an d those in differen t districts correlated .

For several y ears he acted as secretary o f“the British Asso ciation

Committee on Life - zon es in the British Carbon iferous Rocks ”

,

an d n o t on ly co llected assiduously himself but also iden tified mucho f the material obtain ed by o thers . The comparative lack ‘

of successin this work, so far as the Carbon iferous Limeston e is co n cern ed,was p o ssibly due to the fact that mo st o f the co llectin g was don ein the No rth Midlan d area

,where con tin uous sequen ces are con

sp icuously absen t . Even the results ofVaughan’

s brillian t researches

Obituary—4 Whee lton Hi n d . 7

in the“Bristo l district have n o t been foun d easy o f app lication to then orthern series, although much of Hin d’

s subsequen t work wasdirected towards that en d .

By the discovery o f Pen dleside zon e—fo ssils in the Culm measureso f Devon shire, Hind was able to show that the lower p ortion

'

of. thelatter was homo taxially equivalen t to the former, while the gon iatitefaun a o f the higher Culm strata co n firms Arber’s con clusion that theyare o f Middle Coal - measures age . Desp ite military duties en tailedby the War— Hin d wen t to Fran ce as Lieut . - Co lo n el in Comman d of

the NorthMidlan dTerritorial an d later o ccup ied respon sibleho spital posts in various districts— he foun d time

'

to elaborate theseries of gon iatite zon es, ran gin g from the Posido ‘

nomya Becheri zon eo f the Pen dleside up to the Middle Co al - measures, which he had‘

formulated in 1909,an d

,in co n jun ction with Dr . A . Wilmo re, to

app ly them in a detailed re - examination of the Clithero e district .At an early stage in his Work he recogn ized the n ecessity for a

reinvestigation o f the Carbo n iferous mo llusca ,and the fruits of this

app eared in the form o f three mo n o graphs '

o n the lamelli

bran chs . In con jun ction With Mr . J . T . Stobbs a chart was drawnup in which these fossils, esp ecially the freshwater sp ecies, wereutilized in the establishmen t of ho rizon s in the North Staflo rdsbireCoalfield . Hin d also p ublished an importan t pap er on the mo lluscanfaun a of the Sco ttish Millston e Grit, an d recogn ized the relation shipto the faun a o f homo taxially higher beds in America and Russia .

His most imp o rtan t palaeo n to logical work relatin g to rocks o therthan the Carbon iferous was his descrip tion o f the Silurian Lame lli

bran chs In Mrs . Gray’

s Girvan co llection .

Elected a member of the Geo lo gical So ciety o f Lo ndon In 189 1 ,

he receivedthe Ly ell award In 1902 and the Ly ellmedal In 1917 . He

was also an hon orary member of the So ciété Géo logique de Belgique ,as well as of several British So cieties . When it is remembered thathis geo logical work was don e In such time as could be sn atched froma busy pro fession al life, on e marvels that so much was achieved .

In a p eriod o f thirty y ears, some four of which were sp en t o n warservice

,his published pap ers numbered over eighty , while In additio n

his servi ces i n the iden tification o f fo ssils were largely utilized bythe Geo logical Survey as well as by private workers . Such an outputwas on ly rendered p ossible by his won derful vigour an d en thusiasm .

Whatever the verdict o f the future regardin g the details of his work ,Hind will be remembered as on e o f the p ion eers in the elucidatiorio f the relation ship s of the Carbon iferous ro cks .

1889 . The Natural Fe atures an d Ge o logy of Suffo lk In W . M. Hin d,

Flora of Sufiolk.

Note s on some in tere stin g Ge o log ical Se ction s in North Staffordshire Tran s . N . Staffs . Fie ld Club , vo l . xxiii , p . 77 .

A De scription o f an In l ier of Carbon iferous Lime ston e at Birchwo od

Mo or”

ibid. , pp . 44 1—6 .

478 Obi tuary Whee lton Hi n d .

1890 . Note s on the Curious App earan ce p roduced by the Natural Bise ction

o f some Spherical Con cre tion s in a Yoredale San dston e QuarryPro c . Ge o l . Asso c . , vo l . x i , p p . 424—7 .

With J . Ward an d o the rs . Excursion to North Staffordshireibid . p p . 1 17- 36 .

189 1 . The Ge o lo gy o f Whitmore Tran s . N . Staffs.Fie ld -Club, vo l . x xv ,

p . 40 .

No te s o n a Pre Glacial River bed at Stoke Road , She lton53.

11893. Descr ip tion of a Slab from the Shale above the Kin der Scout Grit,Rabche ste r, Lan cashire GEOL . MAG . , Ser . III , Vo l . X , p . 540 .

Addition s to the Palaeon to l ogy of North Staffordshire ”

Tran s .

N ; Staffs . Fie ld Club , v o l . xxvii , p . 103.

The Affin itie s of A n thracop tera an d A n thracomya Quart . Journ .

Ge o l . So c . , vo l . xl ix , p p . 249—75 .

With Sir J . W . Dawson . Note on the g en us Naiadifes , as o ccurrin gin the Coal Fo rmation o f Nova Scotia ibid .

, vo l . 1, p p . 435—42 .

Pre siden tial Addre ss : Tran s . N . Staffs . Fie ld Club , vo l . xxviii , p p . 1—2 1 .

A Mon ograph on Carbon ico la, A n thracomya , an d Na iadites

(Part I ) . Palaeon t Soc . vo l . x vi ii , p p . 1—81 , p ls . i—x i .

1895 . A Mon ograph o n Carbon ico la , A n thracomya , an d Naiadite -s

(Part II ) ibid . , vo l . xlix, p p . 81—170 , p ls . x ii—xx .

The Chalk Flin ts o f North Staffordshire Co lliery Guardian ,

vo l . lx x , p . 1038 .

With F . Barke . The Boulder Drift in North Staffordshirevo l . lxx i , p . 461 .

On Zon al Division s in the Carbon iferous Sy stem GEOL . MAG . ,

De c . IV, Vo l . III, pp 255 6 1 .

A Mon ograph o n Carbon ico la , An thracomya ,an d Naiadites

(Part III ) : Palaeon t . So c . , vo l . 1, p p . 171—82, p l . x x i .

A Mon ograph of the British Carbon iferous Lame l libran chiata(Part I ) ibid . , p p . 1—80 , p ls . i—ii .

1897 . A Mon ograph o f the British Carbon iferous Lamellibran chiata(Part II ) : ibid. vo l . II, pp . 8 1—208 p ls . iii—x v .

Section in Carboniferous Lime ston e Shale s at Tissin gton , on the

New Buxton an d Ashbourn e Railway”

Tran s . N . Staffs . Fie ld

Club , vo l . xxxi , p p . 1 15

On the Subdivision o f the Carbo n iferous Se rie s in Great Britain an d

the True Po sition of the Beds map p ed as the Yoredale Serie s”

GEOL . MAG . ,Dec . IV, Vo l . IV, p p . 159—69 , 205—13.

1898 . The Life - zon e s of the Carbon iferous Dep o sits of Europ e

Dec‘

. IV, Vo l . V,\ p p . 61—9 .

A. Mon ograph ‘on

’

the British Carbon iferous Lamel libran chiata(Part III ) Pa laeon t . So c . , vo l . III,p p . 209—76 , p ls . xvi—x xv .

The Yo redale Serie s Co ll iery Guardian ,vo l . lxxvi, p p . 709—10,

757—8 .

On Mr . W . Gun n’

s Co rre lation of the Carbon iferous Ro cks o f

En glan d an d Scotlan d ibid . , p n . 506—8 .

189 9 . With o the rs . Life - zon e s in the British Carbon iferous Rocksibid . , vo l . lxxviii pp . 702—4 . Rep ort Brit . As

’

soc . for 1898 , p . 529 .

The Subdivision of the Carbon ife rous Serie s in Great Britain an d

some of the ir Europ ean Equivalen ts Tran s . Edin burcrh Ge o l .So c vo l . vii , p p . 332—60 .

What are the Rea l Equivalen ts of the Yo redale Ro cks ofWen sleydale

in the Midlan ds ? Tran s : N . Staffs. Fie ld Club , vo l . xxxiii , p . 67

On the Corre lation of British an d Europ ean Carbon iferous Beds

Tran s . Man che ster Ge o l . Soc . ,v o l . xxvi , pp . 96—1 12 .

On Thre e -New Sp e cies o f Lame l libran chiata from the Carbo n i ferous

Rocks of Gre at Britain Quart . Journ . Ge o l . Soc vo l . lv .

pp . 365—70 .

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480 Obituary Whee lton Hi n d .

No te s o n the Palaeon to logy of theMarin e Beds In the Co al measures

of North Staffordshire Quart .

”Journ . Ge o l . So c .,vo l . lx i

,

p p . 527—46 .

Review o f Geo logy of Derby ,etc. (Mem . Ge o l . Surv . GEOL . MAG .

,

De c . V, Vo l . II , .p . 547

Note on the Characters o f the Hing e p late in Auiculop ecten semicostatus ibid . De c . V, Vo l . III , p . 59 .

With J'f’eT . Stobbs . The Carbo n iferous Succe ssion be low the Coal

me asure s in North Shrop shire ,Derby shire , an d Fl in tshire ibid .

,

p p . 385 ,—400 445—59

,496—507 .

Fo ssil Mo l luscan Zon e s In the Carbon iferousRo cks o f the Midlan ds

p art i _ : The Natura l i st p p . 253

Lif e - zon e s in the . British -Carbon iferous Rocks Rep . Brit . Asso c .

for 1905 . p p . 171—4 .

1907 . Ditto ibid . ,for 1906, p p . 302—1 3.

Sp eculation s o n the Evo lutio n o f the River Tren t Tran s . N .

Staff s . Fie ld Club , vo l . x li , p p . 93—100 .

Fo ssil Mo l luscan Zon e s In the Carbon ife rous Ro cks o f the Midlan ds ,p art ii : The Natura list

, p p . 17- 26 , 90—6 .

The Pa laeon to log ical Succe ssIon o f the Carboniferous Ro cks in the

South , o f the Isle o f Man Pro c . Yorks . Ge o l . Soc . , vo l xvi ,

p p .

'

137—54 .

On the Occurren ce o f Den dro id Grap to l ite s in British CarboniferousRocks ibid . ,

-

.p p 155 7 .

Life zon e s in the British Carbon iferous Ro cks Rep . BrIt . Asso c .

fo r 1907 , p p . 316 17 .

1909 . . De scrip tion o f Two New Sp e cie s o f Lame l l ibran chs from Marin eBan ds o f the Yorkshire Co alfie ld Pro c . Yorks . Ge o l . So c . , vo l . x vi ,

p p . 335—6 .

Lill ie shal l Hil l Tran s . N . S taffs . Fie ld Club ,vo l . xl iii

, p p . 1 12 15 .

'

Pre sen t State o f our Kn owl edg e o f Carbon iferous Ge o logy“

The

Naturalis t, p p . 149—56,163—70 , 228—9 , 245—5 1 .

The Homotaxial Equivalen ts of the Culr'

n of We stern German yGEOL . MAG . ,

Dec . V, Vo l . VI, pp . 468—72 .

On the Lame l l ibran ch an d Gaste rop od Faun a o f the Mil lston e Gritof Sco tlan d

”

Tran s . Roy . So c . Edin burgh vo l . xlvi , p p . 331 59 .

The Lame l libran chs of the Silurian Ro cks ofGirvan ibid . ,vo .l xlvi i,

pp . 479—548 .

Co rre lation of the Yoredale an d Pen dle side Serie s The Naturalist,

p p . 307—10 .

Staffordshire Ge o l . Asso c . Jubile e Vo l . , p p . 564—9 1 .

19 1 1 . Four n ew Carbon iferous Nautil o ids an d a Gon iatite n ew to Gre at

Britain“

Pro c . Yorks Ge o l . So c . , vo l . xvii , p p . 97—109 .

19 12 . Le s Faun e s Co n chy l io log ique s du Te rrain Houil le r de la Be lgiqueMem . Mus . R . Hist . Nat . Be lg " vo l vi , p p . 1 18 .

Temn ochei lus derbi en sis , sp . n ov . Proc . Yorks Ge o l . Soc .,vo l . x ix

,

pp . 18—19 .

Palaeon to log ical Note s o n the Mil lston e Grit Beds be twe en Mashaman d Great Whe rn side ibid . , vo l . x ix , p p . 25—34 .

19 18 . The Distribution of the British Carbon iferous Go n iatite s GEOL .

MAG . , De c . VI, Vo l . V, pp . 434—50 .

The Can in ia semin u la Horizon o f Productus humer'

osu s

p . 480 .

19 19 . With A . Wi lmore , The C arbon ife rous Succe ssion of the Cl ithe ro eProvin ce Pro c . Ge o l . So c . to be published in exten so in Pro c .

York s Ge o l . So c .

1920 . With F. Barke an d A . Sco tt A Quartzo se Con g lome rate at

Caldo n Low, Staffordshire GEOL . MAG“

Vo l . LVII; p p . 76—82

The Distribution of the British Carbon iferous Nautilo ids ibid .,

. p p . 405

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GEOL OG I CAL MAGAZ INEVO LUME LVII.

Nd. III — NOVEMBER, 1920 .

EDIT O R IA L NOTE -

s .

THE Swin ey Lectures fo r 1920 in con n ex IOn w1th the BritishMuseum (Natural History ) will be delivered by J . D . Falcon er

,

M.A .

, D.Se . ,F .R .S. etc

, on Mon days, Wedn esday s, an d Friday sfrom November 8 to December 3 at 5 .30 p .m . in the Geology LectureTheatre

,Royal Scho o l o f

.

Min es Prin ce Con sort Road, SouthKen sin gto n . The subj ect Of the lectures, which will be illustratedby lan tern slides, is The Modellin g of the Earth ’s CrustAdmissio n is free .

a

ON November 7 Professor Alfred Gabriel NathOrst, of Sto ckho lm ,

will celebrate his 70th birthday . In man y fields Nathorst has lefta deep imprin t on our scien ce . As a Sp ecialist he ran ks amon g the

mo st emin en t o f paleeobotan ists, fo r his scien tific results,fo r his

in ven tion of n ew:methods,an d for the large an d admirably arran ged

co llectio n that he has established in the Swedi sh State Museum .

As a pup il an d fo llower of Lin n arsson hi s early studies were largelyo n the P alaeo zo ic ro cks of Southern Sweden ,

where the curiousmarkin gs in the Eophyto n san dston es l ed to his classical memo ir on

the o rigin o f such tracks .

‘

His familiarity wi th the rocks in thefield,with their fo ssIls in the laborato ry ,

an d with the writin gs o f

his predecessors in the library ren dered him the mo st ap propriateautho r o f that useful work Sveriges Geo loge

'

.His love of sp ort (to

which the deafn ess of his later y ears is due ) fitted him to lead tho seexp lo rin g exp edition s to Sp itsbergen an d Green lan d whi ch havemain tain ed the high p lace already gain ed by Sweden i n geographicalresearch . British geo logists, who are proud to greet ProfessorNathorst as almost the sen io r Foreign Member of the Geo logicalSociety o f Lon don , wi ll send him their con gratulation s on achievin gthree - s co re y ears an d ten o f vigorous an d fruitful life

MR . R . BULLEN NEWTON ,F .G.S. lately retired (un der age

- limit)from the Geo logical Departmen t in the British Museum (NaturalHistory ) , has go n e upo n an exp edi tion to Trin idad to examin e thefossiliferous deposits y ieldin g p etro leum in that island . These

VOL . LVII .—No . x 1 . 31

482 Edi tor ia l Notes .

beds were n oticed in the GEOLOGICAL MAGAZINE by the lateR . J . Lechmere Guppy (see GEOL . MAG . 1865, p . 256 ; 1866 , p . 179 ;1870 , p . 235 ; 1874, pp . 404—33 ; 1892 , p . 331 ; 1900 , p . an d

of late y ears have attracted much atten tion .

‘>I<

STANLEY SMITH,M.A . ,

has been appo in ted Reader in Geo lo gyin the Un iversity o f Lon don (Bedford Co llege) in p lace ofMiss C. A .

Raisin ,D .Sc .

,who has resign ed .

>I<

THE David Syme prize o f £100, with medal , for scien tific researchfor the y ear 1920, has been awarded to Mr. Frederick Chapman ,

A . .L S. , palaeon to logist to the Nation al Museum and lecturer i n

palaeorito logy In the Un iversity o f Melbourn e .>I< >l<

DR . GRIFFITH TAYLOR has been app o in ted to the n ewly establi shedprofessorship of geography in the University of Sydn ey . Aftergraduatin g at Sydn ey Dr . Tay lor became a research studen t o f

Emmanuel Co llege , Cambridge , an d was afterwards chief geo l’

ogistin Cap tain Scott’s An tarctic exp editio n . Sin ce then he has beencon n ected with the Federal Meteoro logy Bureau in Melbourn e .

>I<

A FREQUENT con tributor to the GEOLOGICALMAGAZINE ,Dr . Arthur

Ho lmes, Imp . Co ll . Sci . Tech ,sailedforBurma

Sep tember last for several mo n ths (on leave) to carry on geo logicalin vestigation s in that region as to o il an d o ther eco n omics .

>l<

AT the presen t day go od exp osures of the Cambridge Green san d are

seldom seen,but an excellen t opp ortuni ty o f study in g this in terestin g

deposit is n ow to be foun d at the Norman Cemen t Works , n earCambridge . The compan y works the lower part of the Chalk Marlfor cemen t

,and excavatio n s are usually carried down to a few

feet above the Gault . Some n ew p lan t is n ow bein g in stalled inthe pit , requirin g con siderable excavation for foun dation s . Thebase o f the Chalk Marl an d the Cambridge Green sand have beendug through an d about 5 feet o f Gault Is expo sed . There is, therefore , an excellen t clean cut section showi n g the Cambridge Greensand,

an d its relation to the beds above an d below . The p o cketysurface of the Gault , bored by an imals livin g in the Green san dsea,

is well seen,sin ce the burrows are filled with a light grey ish

green sand,con trastin g well with the darker Gault . The pho sphatic

n odules characteristic of the bed are well developed, and the gradualpassage upward in to the, Cen oman ian is clear . NO doubt theMan ager o f the Compan y would be p leased to allow an y geo logistin terested in this bed to visit the pit whi le this excellen t temp orarysection is exposed .

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GEOL . MAG . 1 920 . PLATE X .

“

A gre at Am e rican Ge o lo gist o f the last Ce n tury .

1

PROFESSOR JAMES HALL (1811(PLATE X . )

AMES HALL’

S active career in American geo logy extended. over sixty - two y ears of un in terrupted o fficial con n exion wi th

the State Of New York,a record which stan ds un surpassed in the

history. o f o fficial scien ce . At the age of 25 Hall en tered thegeo logical service of New York up on the organ ization of the NaturalHistory Survey in 1836

,an d

_

his service was termin ated by deathin 1898, at the age of 87 y ears . So great was the span of his lifethat it n ot o n ly covered but formed in itself a large share Of theevo lution o f geo logical scien ce in America . JamesHall’s en thusiasmfor his work n ever dimin ished . His death was .but the in ciden t of.a day , and his life , even to that day ,

was in spired by the un dividedpurp o se to develop and advan ce his scien ce . Such a life could n ot

fail to be immen sely productive , an d his was rich in its output fromthe publication of his first great quarto report o n the Geo logy o f

the Fourth District o f New York (1843) to the last of the thi rteenquarto vo lumes of the Palaeon to logy o f New Yo rk .

When theNatural History Survey was organ izedHall en tered up onit for the first field season in 1837, as an assistan t to -Dr. EbenezerEmmon s

,in the crystallin e ro ck region o f the Adiron dackMoun tains .

The secon d y ear.

foun d him in charge Of the Fourth Districto f western New York

,then a sparse ly settled and still heavily

timbered regi on . Here he gradually un fo lded the beautifullyordered succession o f the Palaeo zo ic rocks wi th their wealth o f fo ssillife , an d it was their richn ess in fo ssils that gaVe birth to his desireand purp ose to -

‘

describe and figure them,an d with them to .verify

an d establish the classification of the NewY ork Formation s as

set forth by the co n clusion s o f his co lleagues o n the State Survey .

No p rovision had been made fo r such a study Of the fo ssils inthe origin al p lan s of the Survey ; when ,

therefore , the time arrivedthat the work was o fficially con cluded in 1843, Hall succeeded inObtain in g the san ctio n of the State

,an d was himself commission ed

to p rosecute this work an d prepare a report o n the Palaeo n to logy of

New York,which was to be in on e vo lume and to be comp leted in o n e

y ear . The vo lume'

actually o ccupied three y ears, an d was fo llowedby twelve more vo lumes, un der the _title of The Palaeon tology ofNew York (which app eared successively in a p eriod of more thanhalf a cen tury ) . The work is still go in g on vigo rously . The New

1 A brief obituary of Profe ssor Jame s Hall, For . Memb . Geo l . So c . Lon d .

1848, app eared in the GEOL . MAG . for Sep tember, 1898 , pp . 341—2 . By the

kin dn e ss of his succe ssor, Profe ssor John M . Clarke , LL .D . ,For . Corr . Ge o l .

So c . Lon d . , we are en abled this mon th to publish some addi tion al n ote s of

our Old frien d an d fe l low - worker, together with an e xce l len t p ortrait .

484 A grea tAmer i can Geo log'ist— m es Ha l l .

Yo rk Series o f Geo logical Formatio n s as set forth by the fourState Geo logists , elicited Hall ’s arden t supp ort in all his descrip tivewo rk up on the fossils

'

of"the se formation s . Some of its terms an te

dated tho se.

n ow . in common accep tan ce thus, Champlainwas an earlier an d better defin ed n ame than Ordovi cian o r LowerSilurian Erian an earlier an d more clearly defin ed term thanDevon ian "

an d o n the basis o f priority o f fossil eviden ce the termTaco n ic o f Emmon s (though this was fought over for two

gen eration s an d,

n ot highly regarded by the New Yo rk geo logists) ,has o n the basis of its fossils a chron o logic right o fway over the n ameCambrian . It was on ly very slowly and with obvious reluctan cethat 'Hall y ielded to the p erson al argumen ts ofMurchison in adoptin gthe term Silurian for the terms in the series that are n ow common ly_or provision ally group ed un der the n ame Ordovician ,an d it is veryin terestin g to a studen t o f the developmen t o f geo logical ideas inAmerica to see how these n ow common ly accepted divisio n s o f thelower ro cks had to struggle for recogn itio n in this part of theWesternHemisphere .The adoption , o n palceon tologt

'

cal groun ds, by the late James Halland o ther American geo logists of the common En glish (an dEurop ean ) names for the division s o f the Palaeozo ic rocks, has beenalready atten ded with the most sp len did results

,an d if carried out

(in tern ation ally ) by the authors of our textbo oks an d the professo rsin o ur co lleges will en able us to syn chron ize all the ' great geo logicalfo rmation s o f the globe .Hall was born an d sp en t his boyhood alon g the coast o f Eastern

Massachusetts, an d acquain ted himself with the marin e life of thoseshores as well as a boy could do who had n o bo oks or teachers .

He walked from his home at Hin gham, Mass ,a distan ce of 200

mi les,to attend the Ren sselaer Scho o l at Troy , n o t far from Alban y ,

N .Y .,and his kn owledge of the common life o f the sea and his wide

acquain tan ce wi th bo tan y were always put to their ultimate servicein his recon struction of the extin ct life o f the Palaeo zo ic rocks . His

work was of n ecessity largely descriptive , as he was en gaged in thep ortrayal o f the successio n o f fo ssil faun as as fa p ion eer in a

_

v1rtual lyunkn own field . All studen ts of his bo oks will bear testimon y to

'theaccuracy an d fidelity o f his work, an d the vo lumes of his earlyy ears are still as essen tial to the study of the Palwozoic faun as of

America as the wo rks o f Murchison to a kn owledge of the SilurianSystem Through his impressive p erso n ality ,

his un restrain edvigour, an d his ability to con vin ce p erso n s in authority that he wasin dead earn est, Hall was en abled to keep his palaeon to lo gical wo rkgen erously supported by the State of New Yo rk , even when o therdepartmen ts o f sci en ce were lan guishin g for public support . But

he did all thismuch as St . Paul carried on hismi ssion ary en deavourshe was often in trouble, and n ot in frequen tly had to fight the wi ldbeasts at court who thought his preachin g fo o lishn ess .

In ciden tally to his o ther work, Hall did manyfin e p ieces of clo sely

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A gr eat Amer ican Geo log i st— James Ha l l .

with the organ ization of the In tern atio n al Con gress of Geo logists,which origin ated from a convo cation of geo logists held in Buffalo ,

N.Y in 1876 . Hall was chairman o f the o rgan izin g commi tteeand was chairman o f the first con gress that met in Paris un der thep residen cy o f Pro fesso r Hebert . He fo llowed the con gresses eagerlyat their subsequen t session s, an d at the age o f 86 he wen t with hisdaughter to Europ e , passin g through En glan d an d visitin g theBritish Museum (Natural History ) o n his way to St . Petersburgto attend the sessio n o f that y ear, an d go in g even so far afield as

the CaucasusMoun tain s . This last great exp erien ce in his life wassomethi n g o f a triumphal pro gress, fo r he was ven erable n ot on lyin y ears but l n exp erien ce , an d carried with him a mo st impressiveperson ality ; His stron g vigorous body ,

his head adorn ed by sn owwhite hair “

an d flowin g beard,and his cheeks

,even at that age ,

bearin g the ruddy tin ts of vigorous health , did n ot fail to attractatten tion wherever he wen t, an d his tour through Russia an d thestates of Europ e comman ded wide atten tionJames Hall has left an in delible stamp up on the history of

American geo logy . The time will n ever come when his work can

be laid aside as n o lo n ger of service or n eeded in aid of the progresso f geo logical kn owledge . What he did was fun damen tal , and thesup erstructure which hi s successors have laboured to rai se can restsecurely up on his foundation s . Hall was n aturally much hon ouredby scien tific societies an d by the bestowal o f man y orders an d

decoration s . He became a Foreign Member of the Geo logicalSo ciety of London in 1848 .

En couraged by such early pi on eers as James Hall an d hi s co n

temp oraries, a ho st o f modern palaeon to logists have bo ldly‘

sailedin to tho se little - kn own seas of p ast geo lo gic time , and havediscovered n ew lands an d n ew faun as and fioras

,addin g vastly

to our kn owledge o f the buried past,furn ishin g at the same timereliable lan dmarks for the stratigraphical worker, an d thus tran sformin g geo logy from a dead in to a livin g scien ce .

ORIGINAL ARTICLES.

The Quartz o se Co n glom e rate a t Caldo n Low ,

Staffo rdshire .

By J VVILFRID JACKSON ,a n d J . KAYE CHARLESWORTH

,

M.Sc . ,Ph .D .

IN theGEOLOGICALMAGAZINE forFebruary , 191 9 (pp . 59 on e o f

the presen t writers, in co llaboration withW. E . Alkin s,described

an exp osure o f a quartzo se con glomerate on the n orth - west flan k ofCaldon Low. The con clusion s arrived at in that pap er wereadversely criticized by F . Barke , Wheelton Hind, and A . Sco tt ina later paper in the same Magazin e . 1 These writers main tain thatthe con glomerate was n o t a con temporan eous depo si t

,but an

assemblage of materials, “ an alogous - to that seen in the WeaverSan d-

p its, south o f the Ribden Min e , about on e an d a quarter milesaway , which had filled up a so lution cavity in the limeston e and hadbecome con so lidated by the perco lation of calcareous matter .

The presen t pap er is written with the obj ect of refutin g thestatemen ts made by these writers as to the mode o f origin and theage of the con glomerate . Durin g the last twelve mon ths quarryin go p eration s have revealed tecto n ic features which clearly prove thatthe quartzose con glomerate is a true in tra—formation al con

g lomerate as suggested in the origin al pap er .

2

To clear the groun d it will be conven ien t to give a short descriptiono f theWeaver San d—p its .

The Weaver San d-

p ita— The deposits in these p its con sist chiefly

o f in coheren t san d-

s,clays, an d pebbles, and closely resemble tho se

o f the series of pockets in the limeston e o f the high groun d o f Derbyshire from Parsley Hay to Wirksworth . The prin cipal pit in theWeaver series

,an d the on e n ow workin g , differs from the adjacen t

On es and from the Derbyshire pits in con tain in g blo cks o f hardsandston e, with and without p ebbles, which are obviously residualBun ter beds . These blocks are erron eously regarded byMessrs . Barke, Hin d, and Sco tt

’

as due to the con so lidation of part o fthe con ten ts o f this p it .

3 They further state that they are simi larlitho logically to the in fillin g at Caldon Low . The remain s of a simi larsand -

p it are still to be seen clo se to the road to Cauldo n village ,1 mileN.N.W. o f theWeaver p its, an d a quarter o f amile SW. of thequartzose con glomerate un der discussion . In this pit a block o f

black Pen dleside shale , con taini n g Posidon iella min or, was found byJ . Allen Howe

,and duly recorded in his paper, No tes o n the Po ckets

o f Sand and Clay in the Limeston e ofDerby shire and Staffordshire .” 4

1 GEOL . MAG Vo l . LVII, 1920 , p . 76 .

2 Ibid ., Vo l . LVI , 19 19 , p p . 59—64 .

3 Ibid . , Vo l . LVII, 1920 , p . 8 1 .

4 Tran s . North Staff s Fie ld Club , vo l . xxxi , 1897, p . 144 .

4 88 J . W. Jackson an d J . K . Char l es’worth— i

Mr . Howe also n o ted the occurren ce of large blocks o f san dsto n ely in g in the p it, which he was in clin ed at the time to regard as theremain s o f an outly in g exten sion o f the Bun ter or Keup er beds .

1

Man y o f these blo cks, some con tain in g p ebbles, are still to be seenhere . Traces o f o ther dep osits o f san d an d p ebbles are still visiblein this n eighbourho od, especially to the S. an d S E . o f Milk Hill ,n ear Waterhouses .

The presen ce o f black shale in these p its is n ot p eculiar to theStaffo rdshire series, as we have n o ted its o ccurren ce in the Lon gcliffPit

,and in o n e n ear Parsley Hay ,

Derby shire . In bo th cases theshale was well - bedded and in a vertical p osition ,

as if it had droppedin bodily . In the latter lo cality the shale con tain ed Posidon ie llaan d obscure p lan t remain s .

That the who le series of these p its, bo th i n Derbyshire an d m

Staffordshire,is pre

- Glacial m age i s clearly proved by the presen ceo f Glacial Drift overly in g them . Durin g our survey o f the pitsrecen tly we made a careful examin ation o f the overburden in everycase, and found that it was sharp ly marked off from the un derly in gsan ds an d gravels , esp ecially in the Derbyshire

'

series . At on e of thep its at Parsley Hay we obtain ed a large boulder of Esk

'

dale gran itean d two o f Borrowdale ash from the overburden

,thus provin g it

to be Drift o f the Irish Sea 1ce— .sheet At the Washmere Pit, n earNewhaven the same Drift con tain ed ice scratched boulders o f

do lerite , Carbon iferous Limeston e, and san dston e . The Drift overly in g the disused pit at Min n in g L- ow y ielded chert, Magn esianLimeston e, do lerites, grits, etc . A do lerite boulder was also foun din the Drift at the Lon gcliff Pit, while from the Drift at the workin gp it at Ribden we obtain ed a large ice - scratched boulder of gritston e .The p resen ce o f Boulder - clay here has lo n g been kn own ,

and was

described by G. Maw inThe Quartzose Cong lomerate .

—In the earlier paper 3 it was po in tedo ut that the condition o f the section exp o sed in September, 19 18 ,ren dered the relation of the con glomerate to the massive Caldon Lowlimeston es (Humerosus beds) somewhat doubtful, but the availableeviden ce suggested an un con formity or a fault . Recen t quarry in ghas revealed a slicken sided surface run n in g W.S.W. alon gthe trun cated ends of the horizon talHumerosus beds, thus suggestin gmov emen t of the quartzo se con glomerate an d asso ciated beds ina more o r less horizon tal direction .

4Blo cks of the con glomerate

~

also show the same slicken sided surface . It is clear from this factthat the con glomerate do es n ot occupy its o rigin al position .

1 Ibid . , p . 149 .

2 GEOL . MAG ., Vo l IV,

1867, p . 250, Fig . 7 .

3 Ibid Vo l . LVI , 19 19 , p . 60 .

4 This fault 1s p robably the con tin uation of the min eral ve in marked on the

l in . Ge o log ical Map , No . 72 , N .E . The ve in is n ow de stroy ed by quarry in go p eration s .

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4 90 J . W. Jackson an d J . K . C'har lesworth

l imeston es is n ot altogether clear they are later than the Caldo nHumerosus beds , and are faulted down alon g with the quartzo sec o n glomerate . They app ear to us to represen t a p ortion of the upp erp art o f the Lon sdah

’

a Subzon e,and .to be related to the fossiliferous

l imesto n es o f the churchyard at Cauldo n to the n orth ,1 which are

almo st certain ly upperD2 . The somewhat similar faulted block o ffossiliferous limeston es opposite the Red Lion In n ,

about half a milesouth , is probably o f the same age .

The horizo n of the Humerosus beds of Caldon Low has been thesubj ect o f some dispute durin g recen t y ears . In 1908 2 they wereten tatively assign ed by Dr . Sibly to the upp er part o f the LowerDibun op hyllum zon e, D, . This position received stron g con firmatio nin 19 18 by Mr. L . M. Parson s

’

researches in Leicestershire (atBreedon Cloud an d Bre

_

edon - o n - the - Hill) . 3 Other workers,in cludin g

the late Dr . Wheelton Hind,have defin itely assign ed them to the

base o f the Visean,viz . C S . A full discussion of this importan t

p roblem can n o t be en tered up on here , but must be reserved for a

future paper dealin g with the horizon o f the Humerosas beds o f

Dove Dale . A prelimin ary article o n this area,by on e of the presen t

writers, has air ady app eared 1n this Magazin e . 5 The Dove Dalelimesto n es are o f the Brachiopod Bed typ e , an d their faun alcharacteristics suggest that their stratigraphical horizon is n earerD2 than D . We are in clin ed to regard the Caldon Low limeston eswith Productus humeros-as as a mo re n ormal

,but less fo ssiliferous,

developmen t o f the Dove Dale series . The sp ecies at Caldon is n otcommo n throughout , but occurs o n ly in well - defin ed beds, associatedwith a few o ther fo ssils

,in cludin g two or three in terestin g forms of

corals,which require further study .

Petrograp hy of the Con glomerate — Wan t of space preven ts a len gthydiscussion o f the various con stituen ts o f the quartzose con glomerate ,but readers are referred to the pap er published in February , 1919(op . cit . ,

p . for the main details . The who le assemblage , in our

o p in ion ,con tain s n o thin g o f later date than the Carbon iferous

Limesto n e .As p o in ted out in the earlier pap er (Op . cit .

, pp . 62 a ro lledshell an d limeston e - pebble co n glomerate forms a strikin g featurea lo n g the boundary o f the Midlan d Limeston e massif on its n o rthwestern and western sides . In p laces this con glomerate con tain sa fair amoun t of well - roun ded quartz , some p ebbles bein g of larges ize . 6 From closer study o f this margin al feature we have n o

1 GEOL . MAG .,Vo l . LVI, 19 19 , p p . 61—2 .

2Quart . Journ . Ge o l . Soc . , vo l . lxiv, 1908, p . 44 .

3 Ibid . , vo l . l xxiii , 19 18 , p p . 94—1004 GEOL . MAG . , vo l . LV,

19 18, p Vo l LVII, 1920 , p . 78 .

5 Ibid . , Vo l . LVI , 19 19 , p p . 507—9 ; se e also Sibly ,ibid . , Vo l . LVII 1920

6 We have se en sp ec ime n s in W . F . Ho lroyd’

s co l lection an d p osse ss o thersfrom similar beds n ear Wetton , Staffs . See also Tran s . Man ch . Ge o l . So c . ,

vo l x xv , 1896 , p p . 124—5 .

The Quartzose Con g lomerate a t Ca lolon’

Low,Stafis . 49 1

hesitation i n correlatin g the Caldon quartzo se co n glomerate with it,an d m assign in g the Who le series to the Cgatharoma subzon e D3.

The same horizon is rep resen ted by the series o f limeston es i n

the small quarries n ear Fi eld House , n orth o f Waterhouses .

1

In some o f the beds here quartz p ebbles and grain s occur

asso ciated with ro lled an d broken shells, p ebbles o f limeston e ,

fish teeth, crin o id debris

,an d corals (several forms) . Some o f

the brachiop od shells an d corals are be ekized,

and stan d out

in relief on j o in t faces . We are a lso of the opin ion that thegreater part, if no t the Who le , o f the series o f limeston es an d

ro lled shel l beds exp o sed in the quarries at Waterhouses belo n gto the same horizon ,

viz . D3. The shell an d limesto n e - pebblecon g lomerate is -well seen in the disused quarry n o rth of the stationit con tain s o ccasion al quartz p ebbles . In this same quarry on e o f

the writers (J . W. J . ) has co llected a n umber o f in terestin g corals ,in cludin g Mlchelz

'

m’

a g lomerata ,Facosc

'

tes p arasiteca, an d Alveolttes

sep tosa . The absen ce o f an y record o f the o ccurren ce of the lastn amed in the south - western district has‘ been sp ecially remarkedup on by Dr . Sibly .

2

It is n ot Without -in terest to n o te that there is stron g eviden ceo f earth - movemen t an d ero sion in the eastern part of the Midlan darea in late D

2times . In a section n ear Youlgreave , accordin g to

Dr . Sibly ,3 black shales of the Pen dleside Series clearly overstepp ed

the trun cated edges o f limeston e beds represen tin g a high level in theLon sdalia subzon e, D2 . This section ,

”

Dr . Sibly po in ts out,

affords eviden ce o f local earth - movement an d erosion ,con tem

p oran eous with the depo sition ,in o ther parts o f the area

,of the

upp ermo st beds o f the Carbo n iferous Limeston e o r the lowest bedso f the Pen dleside Series .

” The Cgathawom’

a Beds,D3,

are

absen t here,and this may be due either to their removal by

denudation du1 in g early Pen dleside time or to the locality havin gformed land durin g Cgathazr on za time . Mr. C. B . Wedd 4 has alsodescribed a similar example o f lo cal un con formity at Darley Dale .It i s n ot improbable that o ther examp les will be found ultimatelyin the Midland area . The formation o f the ro lled shell an d limeston epebble con glomerate (quartzo se in part ) referred to in this articl eseems to us to have been the result of the earth - movemen t ande rosion which produced the above - men tion ed un con formi ties .

Cwnclusi ons — The Caldon quartzo se con glomerate is a trueIn traformation al co

,n glomerate ” depo sited i n D

3times . It fills

an ero sion chan n el l n beds o f D2age at Caldon

,these beds

,together

wi th the con glomerate , havin g been subsequen tly faulted down and

1 The se beds were assign ed to D3 by Sibly in 1908 . Se e Quart . Journ .

Ge o l . So c . , vo l . lxiv ,1908 , p . 6 1 .

2 Loc . cit . , 1908 , p . 48 .

3 Loc . cit . , 1908, p . 63 an d fig . 5 (p .

4 Discussion o f Dr . Sibly’

s p ap er, 10 0 . cit ., 1908 , p . an d Mem . Ge o l .

Surv . : The Geo logy of the Northern Part o f Derby Co alfie ld,e tc .

”

Lon don ,

19 13, p . 35 .

.4 9 2 .C. E . Ti l ley— Me laon orp h

’l sn t'

of

thrust alon g . It '

is con temporan eous with the o ther con glomeratesoverlyin g D2

limeston es round the n orth - western an d westernmargi n s of the Midlan d Limeston e massif . The formation of thesecon glomerates an d the erosion of the Caldon chan n el appear to havebeen the result of earth - movemen t in late, or post, D2 times, eviden ceo f which is presen t in the eastern part of the Midland area

, n earYoulgreave and Darley Dale .

The Me tamo rp hism o f ,the Pre - Cambrian Do lom ite s o f

So uthe rn Ey re Pe n in sula, South Austral ia.

By C. E . TILLEY, B .Sc. ,Emman uel Co llege , Cambridge .

(Con cluded from p .

(PLATE XI . )

THE CALc- MAGNESIAN SILICATE ROCKS OF THE HUTCHISON SERIES

HE rOcks arising from the metamorphi sm Of the more impuredo lom itic sedimen ts are calc- magn esian silicate types in which

al l carbon dioxide has been exp elled . In some o f the ro cks to bedescribed it is clear that sup erposed o n the n ormal metamorphismthere has been a metamorphismby addition o f material from then eighbourin g magma .

The best expo sures of these calc- magn esian silicate rocks are at

Sleaford Bay , and they are here closely associated with the do lomites,o f

'this area . Fragmen ts of this group have been recogn ized at

Fishery Bay to the south , where they o ccur as bars in the Flindersgn eiss, and they are undoubtedly portion s .of the Hutchiso n seriesen gulfed by this in trusion .

The rock - types in clude DIOPSIDE ro ck, with or without quartz orp lagi oclase DIOPSIDE—MICROCLINE rocks

'

with scap o lite orp lagio claseas imp ortan t accessories . Zo isite, titan ite, bio tite an d graphiteare o ccasion ally imp ortan t con stituen ts .

(a) Diop side Rock.

This ro ck forms a promin en t headlan d o n the coast o f Sleaford,

n ear Sleaford Mere,an d boun din g section 14a .

_The in terbeddedro cks here strike n o rthwith a dip of 80 degrees west, to vertical . Onthe west the diop side rock is bounded by impure diopsidic bedswhich pass in to mica an d mica graphite schists, and on the eastit is boun ded by garn et gn eisses . The who le diopside bed is

in timately vein ed by quartz stri n gs, which traverse it i n sill likefashion. On the tran sverse j o in t faces in vein s an d in vugs thereare presen t well - developed prisms an d n eedles o f actin o lite .Un der the micro scope the rock is seen to con sist almost exclusively

o f a co lourless to pale green pyroxen e, with a high extin ction an gle .It is n o n p leochro ic, an d the individual grain s on ly o ccasion allyshow crystallographic boun daries . The rock as seen in han dspecimen s is

l

o f a pale green _ ,co lour an d may vary con siderably

i n texture fromp lace to place . The grain si ze is, however, usually

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Sou th Au stra l ian Do lomi tes . 493

medium an d of a gran ular n ature . The sp ecific gravity is 325 . In

man y cases an in cip ien t alteration to a p leo chro ic actin o lite can beo bserved In the slides . This may develop p eripherally o r in iso latedsp ots through the grain . In the asso ciated quartz vein lets flakes o fgraphite an d little roun ded grain s o f diopside are Often presen tGraphite also o ccurs alon e

g jo in t faces. The dl op s1de ro ck o ccurri n g asan in clusion 1n the ign eous gn eisses o f Fishery Bay is essen tiallysimi lar

,but here it has been in vaded by themagma in the fo rm of

felspar vein s .

In these cases the felspar has been very pron e to alteration ,and

in some slides it is represen ted by its decomp o sition p roducts as

strin gs through the diopside grain s o r between an d at the corn e-rsthese in dividuals . The origin al felspar was a p lagio clase an d hada refractive in dex greater than C. balsam . In some cases it was as

basic as a calcic an

'

desin e . Scap o lite an d zo isite are presen t inaddition to sericite as decomp osition p roducts . Horn blen de may in

'

some cases be seen as streaks traversin g the ro ck in han d - sp ecimen s .

Un der the mi croscop e an examp l e o f this typ e was seen to con sisto f diopside and horn blen de in tergrown without an y clear eviden cethat the amphibo le has been derived from it .A slice cut from a diop side ro ck develop ed as a result o f thein trusion o f a quartz vei n in the do lomite of the Waterfall Creek ,Hun dred ofHutchison ,

shows grey ish diop side , tremo lite , an d quartz .The rock has been crushed a n d the tremo lite is the result of thecrushin g of the diop side . The quartz shows un dulo se extin ctio n ,

an d is in con tact with tremo lite,this relation bein g con trary to that

exp ected, if tremo lite had arisen as a direct result of silication .

(6) Diop side—Microclin e Rocks.

Eastl

o f the diop side headlan d the ro cks pass in to more alumin ousbeds, in which diop side is still an imp o rtan t co n stituen t . Thesero cks have all the app earan ces o f represen tin g a tran sition in tocalcareous shales an d San dston es from purer do lomitic sedimen tsprior to metamorphism . They are in terbedded with ro cks that . aren ow garn et gn ei sses, sometimes carry in g silliman ite

,an d these are

probably also metamo rpho sed sedimen ts .

The diop side - bearin g rocks have also suffered in trusion from

quartz so lution s, as represen ted by quartz vein lets, an d strin gstraversin g them,

and these on weatherin g give the rock quite a

serrated app earan ce . _ When examin ed'

un der' the micro scop e theserocks are seen to con tain the fo llowin g silicates, to the exclusion o f

all carbon ate min erals—di op side , microclin e , p lagioclase, scap o lite ,bio tite

,titan ite, zo isite, and quartz . Graphite is also usually

presen t in small amoun t . A typical section is described as un der .

No . 160 . Diopside is presen t i n light green co loured grain s an do ften shows crystal outlin es . The extin ction an gles o f thesediop sides reach a value Of 44 degrees, and the light green co lour o f

the min eral suggests the p resen ce Of the heden bergite mo lecule

4 94 C. E . Tracy— Metamorp hi sm of

en terin g the con stitution . At the p eriphery and alon g cracks or

cleavages it is chan gin g to actin o lite . The p o tash felspar ispresen t in con siderable amoun t . The type o f extin ctio n is thatcharacteristic of certain micro clin es in which a submicroscop 1ctwin n in g is suggested .

Scapo lite is p len tifully distributed in brillian tly p o larizin g grain s,whose double refraction is greater than '035 , an d it has the highrefractive in dex corresp on din g to a scap o lite of the meion ite en d of

the series . It is un iaxial an d op tically n egative . The rectan gularcleavages are well develop ed : they are n ot p in ako idal cleavages,but prismatic, an d the extin ction of sectio n s which are n ot quitebasal is in accord with this . This apparen tly is the case for thescap o lites o f the Grenville series o f On tario as described by Adams

an d Barlow .

1 The min eral separates with p lagioclase from the rockp owder in a bromoform - ben zo l so lution of den sity It disso lvesin a mixture of stron g hydrochloric and hydrofluoric acids withoutany eflerve scen ce .

In thin section the in terferen ce co lours are as high as third o rdergreen s when ‘ the diop side gives seco n d order y ellows .

Plagio clase is presen t in small amoun t, with the n sual twin n in glamellae . Separated from the ro ck p owder, it has a sp ecific gravitygreater than 2 72 . The refractive in dex is greater than 15 6, buto n ly a few section s Show a R . I . greater than ,

8 is just un derMost section s give a n egative sign , but a few show p ositive

birefrin gen ce . The symmetrical extin ction s of albite lamellaereach 40 degrees . The plagioclase is therefore a by town ite , an dpo sitive section s indicate a tran sition to labradorite . The grain sare sometimes bo rdered by a scap o lite frin ge , and in o ther cases thegrain is broken up and con verted in to a co n fused aggregate o f

scap o lite, wi th iso lated sectors of p lagio clase .The remain in g co n stituen ts are subordin ate in amoun t . Stron gly

p leo chro ic actin o lite borders the pyroxen e, and in a few casesapp ears to be in tergrown with a small amoun t o f biotite . A min eralregarded as sphen e is sparsely distributed through the ro ck . It isusually in more o r less roun ded grain s

'

o f a brown co lour. Occasion ally ,

however,traces o f prism an d pyramid faces can be seen ,

an d in suchcases the extin ction is distin ctly oblique . Pleo chro ism is oftenn oticeable

,the chan ge bein g from a light to a deep er brown .

The axial an gle is n o t large to judge by the curvature of theisogyre s . The birefrin gen ce is po sitive , an d a stron g axial dispersionis to be observed p v.

Graphite is presen t in sp on gy and irregular flakes, apatite inprisms an d grain s embedded in microclin e, or asso ciated withscap o lite . Quartz is quite localized, and is probably part of a

vein let which cuts the rock .

In an other ro ck (216) p lagio clase takes the place o f scap o lite inthe typ e already described . The p lagio clase is o f the same

1 F. D . Adams an d A . E .

'Barlow, Mem . Ge o ] . Surv. Can . , No . 6 , 19 10, p . 102 .

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4 96 C. E . Ti l l ey— Metamorjohi sm of

THE CHEMISTRY OF THE DEVELOPMENT OF THE CALc - MAGNESIAN

SILIOATE ROCKS .

We have already referred to the o rder o f developmen t of metamorphic min erals in an impure do lomite . The min erals which firstmake their app earan ce are predomin an tly silicates or alumi n atesOf magn esia,

an d it is in accordan ce with this greater chemicalactivity of MgO that the domin an t lime - bearin g min erals , as

scap o lite, plagioclase, etc . , are on ly developed when magn esia hasbeen satisfied .

1 The formation o f diopside o ccurs in the presen ceo f abun dan t silica

,and the o ccurren ce o f exten sive beds o f practically

pure diopside is elo quen t eviden ce that the origin al sedimen t hadthe lime - magn esia ratio o f a true do lomite . The exp lan ation o f theformation o f such large masses o f diop side ro ck

,. however

, bymetamorphism,

wi thout the addition o f material,i . e . by residuary ‘

crystallizatio n ,deman ds just that amoun t o f silica uniformly

distributed through the mass to satisfy the diopside reaction . Thecon dition s y ieldi n g such a distribution are

,however, n ot likely to

have been attain ed, and the field eviden ce stron gly favours the viewthat addition o f material in the form o f the n umerous quartz vein swas in p art resp on sible for the diop sidization . .The ro ck as n ow

con stituted is .to be regarded as a hybrid typ e , in which silicationwas partly effected by residuary crystallization an d completed bysilica so lution s from the n eighbourin g gran ite , n ow represen ted bythe n umerous quartz vein s traversin g the diop side ro ck . Moreover,in the adj o in in g calc- magn esian silicate ro cks, there is abundan teviden ce o f vei n in g of these rocks by quartz strin gs . For thesame reason it is doubtless to the addition of material from themagma

,rather than to detrital material presen t in situ, that we

must ascribe the expulsion o f the last remn an ts o f carbon dioxidefrom some of the more alumin ous beds .

In the Gale - magn esian silicates at Sleaford,an d in the Hutchison

area,however

,there is n o reason— with certain exception s to be

referred to below— to invoke the aid of magmatic material o therthan the purely vo latile reagen ts and silica . The metamorphism,

by addition to these ro cks, is at most a silication .

In the rifted diop side lolo ck in the ign eous gn eisses o f FisheryBay , the mass is p en etrated by felspathic strin gers, and this Is to beascribed to the presen ce of the surroundin g fluid magma .

1 Cordie rite wo uld app ear to be an e xcep tion to this rule . Its abse n ce in

me tamorpho sed l imeston e s is remarkable . A deve lopmen t in accordan ce

with the e quation2 CaMg (COS)2 2H4A12S120 9 Si0 2

(2M0 0 2A120 3 . 5 S10 2) 2 CaCOs 2 C0 2 4H20

cordierite

might be e xp ected, but it would ap p ear that the a lumin a is absorbed in

an orthite,an d diop side forms in stead .

Cal 0'

b <CO3l2 CaC0 3 "l‘ H4A128 120 9 2 8 10 2_ CaMg (S10 3)2 Ca11128120 8 2H2 0 3CO2

Sou th Au stra l ian Do lomi tes . 497

The conversion o f diopside in the diop side ro ck in to actin o lite invugs, alon g tran sverseve in s an djo in ts, is paralleled in the pyroxen ites(altered limeston es) of On tario . as described by Adams an d Barlow .

1

It is stated (p . a deep green horn blen de is also seen o ccasion allyrun n in g through the pyroxen ite in n arrow vein s, as if it had developedalon g cracks .

”

The impurer do lomitic sedimen ts . on metamorphism haveultimately been con verted in to silicate rocks

,in which the mi n erals

diop side and micro clin e are p rime con stituen ts . This asso ciationo f pyroxen e and felspar is o n e o f con siderable imp ortan ce, esp eciallywhen the n ature o f the detrital min erals in the origin al sedimen t iscon sidered . The developmen t of these min erals can be represen tedby the fo llowin g equation ,

in which sericite and quartz are thedetrital materials in vo lved(a) CaMg H

2KA1

3 (SIO4), 3 S10 2CaMg (Si0 3)2 +

‘

KAlSi30 8 A12SiO5 H,O 2 CO2

(6) A12SiO5 CaCOsFl SiO2 CaAl2Si2O,3 CO

and this doubtless represen ts the case where the diop side an d “

microclin e are in timately asso ciated with p lagioclase . How far thereaction has pro ceeded by absorption o f excess alumin a in thepyroxen e is n o t eviden t, thus(c) 4MgCO3 3CaCO3

HQKAI3 (S10 4), 7 810 2

3CaM (SiOg)2MgAi,SiO, 7 co ,+

but the very characteristic association o f these two min erals , oftento the exclusion o f o ther alumin ous typ es in which excess alumin acould be absorbed

,would seem to deman d this equation .

We have already in terpreted the formation o f phlogopite in thedo lomi te marbles as a result of an in teraction between do lomiteand detrital sericite

,or sericite and quartz

,and it would app ear that

with an excess o f Silica this reaction in turn would be furtheradvan ced, the resultan t phlogop ite g ivin g place to diop side and

microclin e . Usin g the min erals of the right - han d side o f thisequation , we have with excess of Silica (ride p . 459 )

(cl ) HQKMgsAl (SiO,)3 MgAl2O, 5 CaCO3—l 10 S10 2

4 CaMg KA1S130 8 CaAl2Si20 8 5 CC2 H,

O .

Diopside microclin e rocks may thus arise . by'

simple residuarycrystallization or

_the metamorphism may p ossibly take p lace in

two stages . Firstly residuary crystallization may be on ly sufli cien t

to produce the phlogop ite marble stage, an d by a later additivemetamorphism 2 the silication o f this ro ck to a diopside mi cro clin etyp e . For the ro cks under discussion the view that residuarycrystallization is so lely resp on sible for the mi n eralogical chan ges

1 Lo c . cit . sup ra , p . 9 1 .

2 Cf . J . E . Spurr, Econ . Geo l vo l . vii , 19 12 , p . 455 . This term would be

embraced un der V. M. Go ldschmidt’s te rm p n eumato lytic con tact

metamorphism

VOL . LVII .

— NO . XI .

498 C. E . Ti l ley—Metamorp hi sm of

invo lved is in accord with bo th field an d n n cro scopic eviden ce forthe maj ority of types investigated . Where, however, the rocksare in timately p en etrated by quartz strin gs, comp lete decarbon ation"

can n o t n ecessarily be in ferred, pri or to the i nvasion by silicaso lution s from the gran ites, an d In viewo f the variability o f com

p o sition of sedimen ts o f this typ e it is probable that the expulsionof the last traces of carbon ate min erals from some o f these types wasaccomp lished by siliceous invasion s .

Referrin g to the equation it will be seen that the diop sideis shown to con tain the Tschermak mo lecule

,an d the validity o f

this equation would be con siderably stren gthen ed if it were possibleto detect the presen ce o f alumi n a In these diopsides, apart from the

fact that excess alumin a may en ter an orthite In man y cases . The

optical characters shed little addition al light o n this questionbeyon d confirmin g that a .pure diopside Is n ot invo lved 1 (p .

In the case Of detrital bio tite bein g a source of some o f the MgOof the pyroxen e, there may be n o available alumin a to be dealtwith , 'thusK2Mg2A12 (S10 4)3 2 -CaCO, 7 S10 2 2 CaMg (SiO3)2

2 KAlSisO8 2 00 2 .

But as in mo st biotites part of the K 1s rep laced by H,this would

n ot be the gen eral case .The remain in g ,

min erals accompan y in g the diopside—microclin easso ciation call fo r some remark .

Bytowni te is characteristic .

With the utilization of all magn esia from the do lomite mo leculeresidual calcite is free to react wi th alumin a an d silica , in the fo rmof sericite or kao lin

,an d an orthite may thus arise , e .g .

CaCO3 A120 3 2 SiO 2 H20 CaA12S120 8 2 H20 00 2 .

kao lin an orthiteIf sericite be the source of alumin a,

the po tash would y ield microclin e , an d the soda of the sericite coul d be distributed between themicro clin e an d an orthite . (Seealso the equation s already set down )With the dwin dlin g o f plagio clase in these ro cks, a member o f

the scap o lite group takes its p lace , an d although these two mi n eralsmay o ccur together the “

ro cks are usually characterized by an

abun dan ce o f on e or -the o ther . The scap o lite o f these rocks has beenShown to approximate to meion ite in compo sition .

In view o f the recen t work o f Borgstrom 2an d Sundius 3 on the

co n stitution o f Fin n ish an d o ther scap o lites, in which they show1 Diop side micro clin e ro cks have be en de scribed by J S. Flett ( The Ge o logy

o f the coun try aroun d Bodmin an d St . Auste l l

p . an d by E . B. Bailey The Geo logy o f Ben Nevis an d Glen Co e

p p . 190 an d the asso ciation s in tho se case s would

se em to deman d the pre sen ce o f an alumin ous diop side as these in ve stigatorshave suggested .

A

2 L . H . Borgstrom , Z e itschr . Kry st . Min . , vo l . l iv ,19 14 , p . 238 .

3 N . Sun dius , Bul l . Ge o l . In st . Un iv Up sala, vo l . xvi , 19 19 . pp . 96 106 .

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500 J . W. Greg ory an d Ethe l Curr i e

apart from vo latile agen ts— is limited to silica . Where the diopsidemasses have been en gulfed as in clusio n s in the 1gn eous gn eiss, thero ck i s traversed by felspathic vein s derived from the fluid magma .

The wri terwishes to record his indebtedn ess to Dr. Harker,F .R .S. ,

for en couragemen t and critical discussion durin g the progress of

these studies .

EXPLANATION OF PLATES IX AND XI .

PLATE IX .

FIG . 1 .

— Forsterite Marble , Sleaford Bay . The min erals shown are calcite

(turbid) , do lomite (limp id) . The dark grain s are forsterite,showin g 0 10

cleavag e s . Near the ce n tre Is a basal section o f eden ite . Magn . 28 diame ters .

FIG . 2 .

—Forsterite . Marble , Sleaford Bay . Con stitue n ts :o

forsterite , withserp en tin ous de comp o sition , calcite , do lomite . Twin n in g lame llae in

do lomite are'

se e n in re lation to the rhombohedral cleavage s, in the clear

grain be low o n the left. Magn . 28 diameters .

PLATE xXI .

FIG . 1 — Diop side Rock , Sleaford Bay . The dark ban ds are di op side ,an d

the white are quartz ve in s . The reticulation of the latter is cle arly marked .

FIG . 2 .

—Diop side—Micro cl in e Ro ck . The clear cen tral area is micro clin e . In

the upp er half o f the section are basal section s o f scap o lite showin g 1 10

cleavage s at right an g le s, an d diop side . Magu . 28 diameters

.

Echin o ide a from weste rn Pe rs ia.

By J . W. GREGORY an d ETHEL CURRIE, Geo logical Departmen t,

Un iversity , Glasgow .

(PLATE x 11 . )

THE Geo logical Departmen t o f Glasgow Un iversity has recen tlyreceived from Dr . W. R . Smellie an d Mr . J . V. Harrison some

fossils co llected by them which throw further light on the age of thelimeston es o f the Persian are at the n orth - western end o f Luristan ,

about 100 miles n orth - east of Baghdad . The lo cality , Gilan ,is o n

a tributary o f the Diala , about 30 miles south - east o f Kasr—i - Shirin ,

a well kn own station o n the main road from Baghdad to Teheran .

The geo logy o f this part o f the Persian fron tier has been investigatedby J . de Mo rgan (Miss . Sci . Perse , vo l . iii , p t . i

,Etud . Geo l . , 1905 ,

pp . 71 who has given a geo logical map (ibid ., p l . xix) of an

area about . 60 miles south - east o f Gilan . De Morgan has iden tifiedthere a fo lded series of Cretaceous an d Eocen e limeston es , withlacustrin e and gyp siferous Miocen e beds . The lo cali ty at which thefossils were co llected by Messrs . Smellie an d Harrison is in lin e withthe strike o f the rocks in the area o f de Morgan

’

s map .

Dr . Smelli e’s co llection was made at Iman- Hasan

,n ear Gilan ,

from a limeston e on the summit o f an an ticlin al in lier, which isun co n formably covered by limeston es referred to the Eocen e . Thefo ssils in clude various echin o ids, mo lluscs, brachiop ods, corals

,

and br'

y o zoa . The echin o ids give the best eviden ce of correlation .

His co llection in cludes the fo llowin g echin o ids

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502 J . W. Gregory an d Ethe l Cu rr i e

Figures .

—_

Fig . 2a,

an in terambulacrum, X 4 dia . Fig . 26,

an 4 dia . Fig . 2c, apical disc, X 4 dia .

Afi nities .

— C. . lorin i and C. donia difler froin this sp ecies by theabsen ce o f the vertical arran gemen t o f the epistroma . In thisresp ect the n ew sp ecies mo st resembles C . arn audi Co tt . (op . cit . ,

1866, p . 786) from the Lower Sen on ian o f Southern Fran ce, in which ,

however, it is less develop ed . Amon gst recen tly established sp eciesC . texan a Whitn ey from the Buda Limesto n e , Texas, '

1916 (Bull .Amer . Pal .

,vo l . v

, pp . 9 1—3, p l . x x,fig . described as n early

related to C. doma,differs by havin g more o f its lower p ores in arcs

an d its orn amen tation o f fin e lon gitudin al un dulatin g ridgesC . mortensen i Lambert Ly on ,

vo l . i , fasc . 30, 1911 , p . 176 ,

p l . xvi ) is more tubercular, havin g tubercles on the upper aswell aso n the

,

lower surface . C. liban oticus de_

Lor . , 1901 (No tes pourservir Et. Ech .

,1901

,p . 27 ; of . R . Fourteau, 1913,Bull". In st . Egypt ,

vo l . VII, p . 57, p l . vi , fig . 6 ) clo sely resembles C. lorin i Cott . var .

alp in a ; butFourteau’

s figure shows n o Sign Of the vertical epistroma

o f C. sme lli i .

5 . Pyrin a orien talis Cotteau Gauthier, 1895 (op . cit . p. 68 ,

p l . xi , figs . 1 De Morgan o btain ed his sp ecimen s from Derre - 1Chahi' an d En djir Kuh .

Dr . Smellie’s sp ecimen from Gilan has the dimen sion s— len gth24 mm .

,breadth 20 mm . ,

height 15 mm .

6 . Echin oconus douni lli i Cot teau Gauthier, 1895 (ibid . ,

p . 70, p l . xi , figs . 9 De Morgan’

s specimens are from Dérre- i

Chahr and Aftab .

‘

Dr . Smellie co llected two sp ecimen s (No s . 5 an d 6)

Length.

27 mm .

25 mm

No . 5 shows well the arran gemen t o f the po res n ear the peristomein oblique trip lets (Fig .

7 . Hemiaster parthien s Gauthier, 1902 (ibid . , p . 137, pl . xx ,figs . 1 an d De Morgan

’

s sp ecimen was obtain ed in Luristan ;the exact lo cality is un kn own .

In Dr. Smellie ’s sp ecimen (No . 6d) the dorsal keel is broken ,

an d the apical disc is hidden by the in terambulacral areas whichhave been pressed over it .Dimen sion s .

— Len gth 28 mm .,breadth 27mm . ,

height 18 mm .

Dr. Smellie has sen t with the echin o ids a few mo lluscs whichin clude some y oun g oysters, the Logiha rhorg

'

an i Douville. Thebrachiopoda in clude Terebratula brossardi Th . Per .

The age of this faun a i s un questio n ably Sen o n ian ,an d apparen tly

Campan ian . It corresp on ds with the faun a o f the echin o id limesto n e of de Morgan ,

who p laced it in the Mastrichtian , but at

the base of that division . The eviden ce of the echin o ids is in favouro f the horizo n bein g p re -Mastrichtian ,

but stil l Sen on ian .

Echi n oidea fr om Western P ersia . 503

The seco nd faun a was Co llected by Mr . J . V. Harri son In thesame district , at the lo cality o f Tan g Diarab ,

n ear Gilan . Thefossils in clude some echin o ids, mo st o f which have be en rather(disto rted.

The co llection in cludes the fo llowin g sp ecies :1 . Schizaster stei n /dis Agassiz Desor

,1847 ; Gauthier, 1902

(o p . cit . , p . 172, pl . xx11i, fig . Obtain ed by de Mo rgan from theUpp er Eocen e at Mo llah Ghiavan. Mr . Harrison ’

s specimenfrom the Upp er Eo cen e at Tan g Diarab . It is somewhat distorted .

Dimen sion s — Len gth 48 mm . ,breadth 44 mm . ,

height 25 mm .

2 . Schied -s-ter rimosus Desor, 1847 Gauthier,1902 (ibid . ,

p . 174, p l . xx iii , fig . De Morgan

’

s sp ecimen s are from the Upp erEo cen e at Mo llah Ghiavan .

Mr . Harriso n ’

s sp ecimen from Tan g Diarah is p o orly preserved .

This sp ecies resembles S . cicin alis in man y way s . It is distin guishedtherefrom by its un paired and '

paired an terior ambulacral g ro oves_bein g n arrower

,and by the p osterior petals bein g re lative l

’

v a littlel o n ger .

3. Ditre in aster n ux (Deso r) , 1853' Gauthier

,1902

,(op . cit . , p . 164,

p l . xxi, figs ._

9 De Morgan co llected man y sp ecimen s from theUpp er Eocen e at Mo llah Ghiavan . Mr . Harrison ’

s sp ecImen s from

Tan g Diarab have the fo llowin g dimen sio n sLen gth. Breadth. He ight.

24 mm . 22‘

mm . 19 mm .

23mm . 2 1mm .

13mm . 1 1 mm .

These dimen sio n s do n ot agree'

with tho s e o f de Morgan’

s specimen swhich are as bro ad as they are lo n g but Mr. Harrison ’

s specimen sare somewhat crushed . They may belon g to the oval variety o f

D . n ux men tion ed in Pal . fran e.,Terr . tert .

,vo l . i

, p . 422 .

4 . Euspatangus gh-ia -

van en sis Gauthier, 1902 (o p . cit ., p . 156,

p l . xxi , figs . 1 an d This sp ecies was orIgI n ally obtain ed by.

'

d e Morgan from the Upper Eo cen e at Mo llah Ghiavan .

Mr . Harrison ’

s specimen s are from Tan g Diarab . Dimen sio n sLength. Breadth. He ight.

30 mm . 26 mm . 13mm .

22 mm . 20 mm . 10 mm .

24 mm . 2 1 mm 10 mm .

The age o f this faun a is un questio n ably Upper Eo cen e . SomeMiddle Eocen e echin o ids are kn own from the Pusht - i - Kuh area , but

n o n e o f tho se Middle Eo cen e ‘

sp ecies is presen t in Mr . Harriso n ’

s

c o llectio n ,

5 04 F. H . Hatch— The Ir on Or e Supp l i es of the Wor ld .

The Iro n Ore Sup p l ie s o f the -Wo rld.

By F . H. HATCH,Past - Presiden t In st . '

Min . Met .

The fo llowin g article original ly app e ared in the s p e cial Iron an d Ste e l

n umber o f the Times Trade Sup p leme n t on July 2 1 last . It is here rep rin ted ,

with some smal l addition s , by the courte sy Of the p rop rie tors of that j ourn al .ITHIN the limits. o f a brief - article suCh as this must n ecessarilybe

,

'it is imp o ssible to do . more than indicate the chief SourcesOf iron - ore supp ly . The subj ect is a. big o n e , an d Of great imp o rtan ce ,n ot o n ly to the British iro nmaster, but also to every - in habitan t ofthis coun try . I am therefore p leased to be able to state that theFederation o f Iron an d Steel Manufaclmrers has n ot on ly askedthe Imperial Min eral Resources Bureau to prepare a summary of

the ex istin g in formatio n as to the iro n - ore supp lies o f the world, butis also assistin g to fin an ce

_the in quiry . This will mean a moremp lete survey than is p o ssible toAn y attemp t to estimate the world’

s 1ron ore resources is comp licated bo th by the diversity of the productsmanufactured from theraw material an d by the numerous factors which go to con n ote ac ommercial iron - ore . Amon g these the iro n con ten t

,the presen ce

o f ben eficial o r deleterious con stituen ts , _ phy sical con dition ,

geo graphical p o sition ,an d mean s o f tran sp ortation are all co n

sideratio n s o f the first imp ortan ce .First con sider the iron—con ten t . Accordin g to the estimate o f the

American geo logist , Clarke , the crust o f the earth co n tain s 4 4 p e rcen t o f metallic Iro n

, of which but a very minute fraction has beensufficien tly con cen trated by geo lo gical agen cies to form commerciallyavailable Iron ores : for on e tOn o f these that co n tain s 60 p er cen to f iron there are very man y to n s that co n tain 50 p er cen t ; whilefo r o n e to n that con tain s 40 per cen t there are vastly more thatcon tain 30 p er cen t , an d so on . The. amoun t o f reserves in an irono re field can

,therefore

,be in defin itely in creased by lowerin g the

grade o f the material to be in cluded .

With regard to the presen ce o f ben eficial oro f deleterious con

stituen ts,what 1s prejudicial In o n e case is be n eficial i n an o ther .

The requiremen ts o f the —smelters are decisive o n this head . If

haematite p ig i ro n for the acid pro cess o f steelmakin g i s required,

phospho rus i s barred ; if, o n the o ther han d,the Iron is destin ed

for the basic p ro cess, pho spho rus is a desideratum . Titan iumrules out vast bodies of o re con taini n g a high percen tage of iron ,

because the p resen ce o f titan ic acid in an y n o tabl e prop e r-tion raisesthe temp erature of fusion an d leads to greater fuel con sump tion an d

a heavier,

blast . '

A small quan tity of man gan ese , on the o ther han d,

is ben eficial , sin ce it helps to get rid o f sulphur: A high Silicacon ten t is an Obj ection , because of the limeston e that has to be addedto the charge to n eutralize the acid co n stituen t; thereby reducin gthe output p erf urn ace an d in creasin g the co st p er ton o f pig but

a calcareous ore is sought after, sin ce it is either self- fluxin g or can ,

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5 06 —The Iron Or e Sup p l i es of the Wor ld .

headin gs of ore"

to be go t (1 ) by op en - cast wo rk an d (2) byun dergroun d mIn In g , from

I

'which I have made a deduction for theo re won durin g the y ears 1 917—19 .

Ope n - cast,Min in g ,

mill ion mil l ionton s , ton s .

CLEVELAND MA IN SEAM

No rth Yo rkshire .

MARLSTONE

Lin co ln shire ,Le ice ste rshire , Oxford

shire , an d Warwickshire .

FRODINGHAM BED

No rth Lin co ln shire .

NORTHAMPTON BED

No rthamp to n shi re Hun tin gdon shire ,Rutlan dshire

,an d Lin co ln shire .

To tal

In additio n ,26 millio n to n s are assign ed - to the Westbury

(Corallian ) iro n ston e , an d 10 million to the Raasay iron ston e , n eithero f which are at presen t bein g wo rked as a source o f iro n . This brin gsthe to tal fo r the Jurassic iron sto n es to million . It is n o t claimedthat these figures are estimates o f actIially merchan table ore . It ispossible that

o

much o f the low-

grade ore that it is n Ow foun d profitablet o work In Op en quarries will n o t con stitute an econ omic prop o sitionwhen m in in g has to be resorted to .

'

The :reserves o f“

. clay~iro n ston e s an d blackban d ironston es in

the Carbo n iferous strata o f En glan d an d Wales are“ estimated

by the Survey. at millio n to n s . The 'S co tch Coalfieldsare estimated to have a

_

reserve o f 93 millio n ton s o f iro n sto n emakin g millio n to n s in '

all . Much is in cluded that in al l

p robability will n ever be min ed . The richer an d thicker seams o f

blackban d have lon g Sin ce been wo rked out,an d the presen t output

comes main ly from North Staffordshire an d Sco tlan d . In 1 918 out

Of a to tal output o f to n s o f Co al Measure iron ston e ,ton s came from tho se districts . The clay - iro n sto n es, 150 0

are n ot worked sy stematically excep t in a' few p laces ; in man y

collieries the clayband ribs are o n ly taken down in brushin g,

” theroads

,an d in t he case o f a ball - iro n ston e the balls are put aside as

they o ccur durin g the wo rkin g of the coal , o r fireclay ,as the case may

be,an d marketed when - a sufficien t quan tity has accumulated . The

o utput of Co al Measure iron sto n e, which amoun ted to over 6 mi llio nton s p er an num in the ’Seven ties, has been fallin g for man y y ears,and is how little over a millio n ton s p er an num . The Director o f theSurvey ,

in an in troduction to the Memo ir o n the Carbon iferousBedded Ores

,states his belief that un der presen t con ditio n s o n ly

about half the amoun t estimated would be available , an d in the .Memo ir dealin g with the iron - ores o f Scotlan d a 30 p er cent deduction

F. H . Hatch —'

The Ir on Or e Supp l i es , of the Wor ld . 507

for lo sses in min in g is suggested . For the presen t purpo se a roun d

50 p er cen t o f the to tal given I

for areas partially develop ed is taken ,

which brin gs the to tal reserves fo r Coal Measure iron sto n e down ‘

to

575 million to n s of o re o f about 30 p er cen t grade .In all

, therefo re, the low -

grade o res of the Un ited Kingdomare

estimated at 3,219 million

, o r, say ,in round figures million ton s

o f 30 p er cen t oreThe reserves o f low-

pho sphorus haematite of Cumberland an d

Lan cashire are estimated by the Survey at 40 million ton s . The.grade may be taken at 50 p er cen t .

SPAIN AND NORTH AFRICA

Spain has In the past been the prin cipal source o f supp ly for thehigh grade low-

pho sphorus ores used in Europ ean furn aces . Thep roduction reached 10 millio n ton s in 19 13 ; but it fell to about halfthat amoun t durin g the War . For man y y ears

I

British makers of

haematite p ig for Bessemer an d Siemen s Martin steelworks haved erived the greater p rop ortio n o f their o res from Bilbao . (some2 1 million ton s p er an n um ) ; but three quarters of the workableo re has already been min ed,

an d fo r some time there has beena gradual deterioratio n in quality due to the exhaustion o f thericher mi n es .

' The low-

pho sphorus ores of Bilbao con sist of. cen a , camp an i l ,rubi o (all thre e varieties of haematite) , an d sp athic (the carbo n ate )but the qualities now

exp orted are practically con fin ed to rubio

and calcin ed “spathic ” The stan dard guaran tee for best rubio

is 50 p er cen t iron ,8 p er cen t Silica,

an d un der 02 pho sphorus, butman y shipmen ts run about 47 p er cen t iron ,

10 p er cen t silica ,an d

025 pho sphorus . The guaran tee for best calcin ed spathic is

56 p er cen t i ron ,but o n accoun t o f fuel scarcity cargo es of abo ut

54;p er cen t iron an d 9 1 p er cen t silica are delivered . Amon g o thero res imp o rted are the San tan der .washed granular ores, but these ,bein g higher i n phosphorus, can o n ly be used In combin ationwitha co n siderable prop o rtion o f o ther purer o res . Rubio ore is alsoworked at Castro (Dicido ) in San tander, an d con siderable reserveso f low p

—bospho rus an d low silica o re with Iron 47 p er cen t exist inAlmeria (Alqui fe) . A large quan tity o f o re is

I

min ed In Seville an dTeruel (Sagun to ) . Dep osits o f haematite , magn etite , brown o re

,

a nd carbo n ate are also kn own in the fo llowing provin ces Guipuzcoa,

Ovi edo,Leo n

,Lugo ,

Malaga,an d Gran ada ;but they have n o t been

much develop ed an d the exten t to which they will be worked in thefuture dep en ds o n the results o f in vestigation an d the prOViSion of

adequate tran sp ort facilities . Few of the ores are equal in qualityto tho se o f BilbaO .

The Sto ckho lm estimate fo r the actual reserves o f Spain broughtup to date by the Imp erial Min in g Resources Bureau,

i s 650 millionto n s

,of which 28 millio n is credited to Bilbao .

High—grade o res (averagin g about 50 p er cen t iron ) are found o n

508 E. H. Hatch— The Ir on Ore Supp li es of the Wor ld.

the. n orth coast o f Africa in various p arts of the Atlas Moun tain sin Algeria, Tun is , an d Morocco in large part they are o f Bessemergrade . The production o f these fields amoun ted in 1913 to clo seo n 2 million ton s, of which three—quarters of a million wen t toEn glan d . The prin cipal producers are Ben isaf, Zaccar, an d Timezritin Algeria ,

Dj erissa in Tuni s, an d Riff in Morocco . It is estimatedthat t he output can be in creased by half a million ton s or more ay ear by comp letin g the railway from the p ort o f Bon a to the Ouen zaand Bou Kadra min es , which are in Algeria n ear the Tuni sianborder, an d about 120 kilometres from the coast The reserves forNorth Africa have been estimated at from 100 to 150 million ton s .

SCANDINAVIA .

Swedish iron has lon g been celebrated for its purity an d gen eralexcellen ce . The l ow-

pho sphorus ore used in its manufacture is inthe main magn etite, an d comes from a number of o ld mi n es i nsouthern Sweden

,amon g which may be men tion ed the celebrated

Dan n emora an d Persbergm in es . It is smelted lo cally with charcoalan d the reserves are comparatively -

small . In cen tral Sweden thereare some large haematite dep osits, as

,for examp le , tho se o f

Gran gesberg an d Norberg , which y ield ore averagin g 60 p er cen tiro n an d high in phospho rus . The reserves are estimated at about100 millio n ton s .

The main resources_

o f Sweden are in Lapp lan d . Great dep ositso f iro n - ore o ccur there , main ly magn etite an d,

as a rule ,high in pho sphorus, although a trifli n g prop ortion is o f acidBessemer grade . The largest an d mo st celebrated ore bodi es are

those o f Kiirun avaara an d Gellivare,the former (together with

Luo ssavaara) bein g credited with a reserve of 738 milli on to n s,an d the latter (in cluding Kokullskulle ) wi th 265 million . Bo th orebodies were fo rmerly worked o n the op en - cast sy stem ,

but un der;

groun d mi n in g has recen tly been substituted at Gellivare . Theyare own ed by the Trafikaktiebo lag Gran gesberg - Ox elOsun d of

Stockho lm,and the ores are so ld by this Compan y on a basis of 60 p er

cen t iro n,as received

,the fo llowin g grades bein g di stin guished by

the pho sphorus con ten t

Grade . Pho sphorus , p er cen t .

No t more than 0 6 .

Not more than 1 0 .

Over 1 0 an d n ot more than 2 0 .

Ove r 2 0 .

The output is limi ted by law to ten s p er an num for

Gellivare,an d 5 mi llio n p er an num for Kirun a .

The shipp in g p orts are Narvik , on the Atlan tic coast, an d Lulea, onthe Baltic . The former is open all the y ear roun d . Before theWar

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5 10 F. H . Hatch— The'

I ron Or e Sup p l i es of the Wor ld.

Fran ce . The ore— geo logically a bedded o o litic iron ston e o f Jurassicage

— is a carbo n ate , partly oxidized to brown ore,con tain in g from

27 to 36 p er cen t iron ,as min ed

,with an average o f 10 p er cen t

mo isture . The ores are in part siliceous, in part calcareous,andgo odsmeltin g charges can be obtain ed by mixin g these two varieties insuitable prop ortion s . A valuable feature is the high -

pho sphoruscon ten t, p ermi ttin g the manufacture of a basic pig con tain in g from1 7 to 1 9 p er cen t pho sphorus, an d sui table for the basic Bessemero r Thomas pro cess . In the greater p ortion o f the field on ly o n e bed

(the grey bed is worked ;but its thi ckn ess varies from 6 to 20 feetan d the reserves are very large , bein g gen erally put down at about

mi llion ton s .

Besides - the min ette ores, Fran ce p o ssesses in Norman dy , An j ou,

an d Brittan y , o o litic bedded ores o f Ordovician age . These occurin a n umber of detached syn clin es either as carbon ate

,o r haematite .The

'

o res (calcin ed in the case o f the carbon ate) average from 45 to

48 p er cen t iron , 10 to 20 p er cen t silica, an d 0 4 to 0 8 p er cen t

pho spho rus . They are smelted to basic iron at the Mon devilleworks, n ear Caen , for the Norman dy depo sits, an d at the Trign acworks, n ear St . Nazaire

,for the Brittan y an d An j ou depo sits . The

reserves are estimated to be about 200 million to n s .

With the cession o f Alsace - Lo rrain e,German y lo st its biggest

o refield,but it retain s a number o f smaller producin g districts, the

reserves of which amoun t to some million ton s .

UNITED STATES

Lake Superior produces four - fifths of the iron—ore output of theUni ted States . (In 19 18 it was 86 p er cen t of a to tal o f 70 mi llion

The o re is derived from a series of ran ges in Min n eso ta,Wiscon sin ,

an d Michi gan ,resp ectively kn own as the Mesabi

,the

Marquette,the Men omin ee;the Gogebic, the Vermi lio n ,

an d the

Cuyuna, the order given bein g that o f the importan ce of the annualproduction . At first al l the o re was obtain ed from open - workin gsby steam - shovel an d o ther forms o f mechan ical excavator, an d wasshipp ed without further treatmen t . Min in g is, however, becomi n gmore an d more n ecessary ,

an d in p laces water - con cen tration,an d

even calcin in g , are bein g in troduced in order to raise the ironco n ten t an d dimi n ish the silica an d sulphur . The ore is in the maina haematite, but in part is hydrated . Magn etite is on ly foun d in theMarquette ran ge an d in small prop ortion . The average iro n con ten t ofthe ore min ed is dimin ishin g , havin g fallen from 56 2 p er cen t in 1902to 52 p er cen t in 19 12 . The pho sphorus con ten t , to o ,

is in creasin g ,the p ercen tage of Bessemer ore havin g fallen from 64 9 in 1902 to

429 in 19 12 .

From the iron ran ges the o re is railed to the shi pp in g p orts of

Duluth,

‘

Ashlan d,Marquette

,an d o ther ports at the western end of

Lake Sup erior, an d from there shipp ed by water to be smelted inChicago ,

o n the shore of Lake Michigan ,o r at Clevelan d an d Buffalo

F. If . Hcatch— The Iron Or e Supp l i es of the Wo r ld. 5 1 1

o n Lake Erie . The bulk o f it, however, 1s pa“

ssed on .by rail toPittsburg an d o ther in dustrial cen tres of Pen n sy lvan ia an d Ohio ,the to tal di stan ce by water an d rail to Pittsburg bemg about1 ,200 miles, an d thus greater than that of the 1ro n min es o f Spainan d Scan di n avia f rom British o r German furnaces . Cheap watertran sp ortatio n on the Great Lakes has made this p o ssible . The oreships are loaded direct from the ore - train s at the rate of 10 ,000 to n si n half an hour, .an d di scharged at the receivin g dock i n less than halfa day . In 1 913 the rate for water tran sp ort an d un loadi n g averagedless than ‘

07 of a cen t,or (at n ormal exchange) “

035 of a p en n y p erton - mi le . Although n avigation is closed for about five -

mo n ths in they ear, an d a sto ck p ile o f 25 mi llion ton s has - to be accumulated at

the loadin g en d,over 60 mi llion ton s a y ear are convey ed in this .

mann er, an d by the en d of 1918 the Lake District had marketed n o

less than 900 millio n ton s of ore .

A recen t estimate o f the available reserves at Lake Sup erior is2,750 mi llion to n s of an average grade o f 52 p er cen t iron

. (Min era lIndustry,The red or Clin ton haematites are bedded o o litic o res o f Silurian .

age cropp in g out on the eastern flan k o f the coalfield from Mary lan d.

throughVirgin ia an d Ten n essee to Georgia an dAlabama . They reachtheir highest eco n omi c developmen t in the Birmi n gham districto fAlabama

,although they are also worked l n Georgia and Ten n essee ,

an d to a small exten t i n Virgin ia . Although the Clin ton ores as a

who le are rather high in silica,this 1s to a co n siderable exten t o ffset

by the presen ce o f a go od prop ortion of lime carbon ate . In cludin gthe Brown Ores worked in the Appalachian Valley an d in Ten n essee ,these south eastern states had

,up to 1918 , produced 10 p er cen t o f

the who le iron o re output o f the Un ited State' s . The availablereserves are estimated at mi llion ton s o f 36 p er cen t gradepho sphoric ore .

The n orth - eastern states (New York an d New Jersey an d

Penn sy lvan ia) , co n tribute 1 p er cen t o f the to tal iro n - oreb utput of

theUn ited States . The o res are derived frommagn etite mi n es'

in theAdiron dack region o f New York

,from Clin ton ores l n Pen n sy lvan ia,

an d from Brown Ore in Northern New Jersey . In the main they are

phosphorie ore , and are used lo cally . The un develop ed reserves,

with an average grade of 35 p er cen t “ iron,are estimated at

2,500 millio n ton s .

The fo llowin g table gives in parallel co lumn s the mo st recen testimates an d those made for the Sto ckho lm Geo lo gical Con gress :

Recen t Estimate s .

Sto ckho lm (M in eral In dustry ,

Mil lion ton s .

Lake Sup eriorS .E . State s (Cl inton ,

etc .

N .E . State s 2 ,500

5 1 2 F. H . Hatoll— The I ron Ore Supp l i es of the Wor ld .

It will be seen that in comparison with recen t estimates,the

Sto ckho lm rep ort ower- estimated the Lake Sup erior area ,but di d n o t

attribute sufficien t imp ortan ce to the remain in g areas . Neitherestimate in cludes an y o f the very low-

grade red o r Clin to n ores, oro f the low-

grade siliceous ores of the Lake District, o f bo th o f whichthere are en ormous quan tities .

BRAZIL .

On e o f the greatest ore reserves o f the world,and certain ly the

greatest reserve o f o re

-

suitable for the acid Bessemer p rocess, issituated in the provin ce of Min as Geraes, in Brazil .The ores are haematite an d magn etite , an d o ccur in ro cks similar

to the ban ded jasp er o fNorth America and South Africa . They varyin grade, but the average iro n co n ten t is over 60 p er cen t

,an d the

phosphorus is in the main well below the Bessemer limit . A pro

p ortio n o f the ore o ccurs in thin lamellae between siliceous la '

y ers, butthere are large masses o f practically pure oxide, like that of Iron OrePeak (Itabira do Campo ) an d the Caue deposit o f Itabira do MattoDen tro

,which is estimated to con tain 80 million ton s of the highest

quality o re . E . C. Harder states that the largest dep o sit con tain s atleast 350 million ton s

,and that there are numerous o re - bodies of from

10 to 50 million ton s . Their p o ssible aggregate ton n age is en ormous ,but with the presen t mean s o f tran sportatio n the greater portion isin accessible . Before the War cap ital was bein g foun d to developthese fields and to provide tran sp ortation ,

an do

it can n o t be lon gbefo re such valuable dep osits will be utilized 1n the world’s markets .

The o re will probably be exp orted i n great quan tity to British an dAmerican Bessemer furn aces .

The econ omically imp ortan t ores of Min as Geraes are usuallydivided in to (a) Bedded or Quarry Ores, con sistin g of (1 ) thick beddedmassive hematite

,an d (2) thi n ly bedded siliceous hematite

jacutin ga ’

(b) Fragni en tal Ores, con sistin g of (1 ) rubble ore (aden udation product o f the bedded ores) , and (2 Can ga (recemen tedrubble) .The massive ore beds vary in thickn ess from less than a fo ot to

more than 300 feet , but they are less exten sive than the jacutin gao res . Leith' and Harder state that sin gle len ses o f j acutin ga are

kn own mo re than 3mi les in len gth an d up to feet in thickn ess .

Of the high grade massive haematite and j acutin ga ,ran gin g in iron

con ten t from 63 to 69 p er cen t,the ton n age was stated by Leith , in

1911,to be probably n ot far short o f the total reserves o f the Lake

Sup erio r district available at that date . The Can ga an d rubble oresare of lower grade ; even these probably average 50 p er cen t iniron

,but the pho sphorus is higher than in the bedded o res .

Estimates o f the total available reserves in the Min as Geraes fieldvary from the co n servative estimate o f million ton s made byDr . Derby for the Sto ckho lm Rep ort , up to recen t estimates o f

million s .

'

Fo r the who le iron o re region of Brazil , Merriam

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514 F. H. Hutch— The Ir o n Ore Supp li es o f the Wor ld.

The amoun t of ore ultimately to be recoverable will depend on

the en gin eerin g skill that can be brought to bear on the problems

o f ven tilatio n an d'

pump in g that such exten sive submarin e min in gwill presen t . E . C. Eckel estimates the eco n omically workable oreat million ton s of 50 p er cen t o re “

within a radius o f 5 mi leso f Bell Islan d . Newfoundland was credited with million ton sin the Sto ckho lm Rep ort .

CANADA .

Very little is kn own regardin g the iron resources of the Domin ion .

Of the 12million ton s of iro n - ore smelted in Canadian blast - furn acesin 19 19

, on ly 5 p er cen t‘

was o f domestic origin ,the balan ce comin g

from Lake Superiormin es in the Un ited States an d from theWaban amin es of Newfoundland . The domestic ores are sedimen taryhaematite ores from Nova Scotia,magn etite from New Brun swick ,Eastern On tario

,Quebec

,and Texada Island

,in British Co lumbia

,

and spathic ore from the Michip ico ten district of On tario . Thecarbon ate ore at the Magpie min e , wo rked by the Algoma SteelCo rp oration In the latter district, averages 34 p er cen t iron for theraw ston e , an d 50 per cen t for the calcin ed material . The low-

grademagn etite dep o sits worked by the Mo o se Moun tain Compan y at

Sellwo od, in On tario ,average 34 p er cen t iron , but the briquetted

con cen trates run as high as - 63 p er cen t .The to tal reserves o f the Domin ion have been estimated at o n ly

150 million ton s,but with the vast un exp lored coun try in Northern

Can ada it is hard to believe that big reserves will n ot some day bediscovered .

SOUTH AND WEST AFRICA .

Iron - ore of various typ es are kn own to exist in South and WestAfrica . Lateritic depo sits similar to tho se of Cuba,

an d characterizedby a rather high silica an d alIImin a co n ten t an d small p ercen tages o fn ickel

,chromium, man gan ese, etc .

, are common in man y parts of thecoun try . On e in Fren chWest Africa has recen tly been foun d to havea reserve of 100million ton s, an d to y ield a n odulized product run n in gover 60 p er cen t iron . Haematite - magn etite depo sits asso ciated withPre - Cambrian ro cks o ccur over large areas but they are gen erallyto o in terlamin atedwith siliceousmaterial to be workable . This type,however

,is stated to be o f econ omic imp ortan ce in Rhodesia . In the

Tran svaal there are exten sive deposits of low-

grade phosphoricores in the Pretoria Beds, n ear Pretoria,

an d at Bo skop , n earPo tchefstro om,

which can be used as mixin g ores ; but the mostvaluable dep osit y et discovered is a hi gh -

grade low pho sphorushaematit e with over 60 p er cen t iron ,

o ccurrin g at Kromdraai ,45 miles n orth - east of Pretoria ,

which it is prop osed to mix with thelower-

grade pho sphoric ores of Bo sko ’p for the man ufacture of basicp ig at Ve 'reen igin g .

With the existin g data n o estimate as to reserves can be made ,but it appears certain that large ton n ages of iron - ore are available

.F. H. Hatch— The Iron Ore Supp li es of the Wor ld. 5 1 5

in . the Tran svaal,from which sui table mixtures for smeltin g to

basic p ig can be made .INDIA .

The fo llowin g particulars with regard to India are taken from a

n o te kindly prepared for me by Dr . Coggin Brown , of the In dianGeo lo gical Survey .

Imp ortan t dep o sits of high -

grade iron - ore,main ly haematite

,

asso ciated with ban ded jasp er, an d in this respect similar to tho seof Lake Superior an d Brazil , have recen tly been open ed up in In dia .

The best - kn own dep osits are tho se of Mayurbhan j and Sin ghbhum ,

in Bihar an d Orissa ; Chan da and Drug in the Cen tral Provin ces ;Kadur in Mysore ; an d Go a . The Mayurbhan j depo sits are bein gworked by the Tata Iron an d Steel Compan y at Gurumaishi n i

,

where a len s of haematite has been proved to con tain 15million ton sfor every 10 feet o f depth . This ore averages over 60 p er cen t iron ,

man gan ese sulphur and phosphorus 0 09 . The basicp ig made from this cm at the Tata Iro nworks

,which are situated

wi thin 40 miles o f the min e workin gs, con tain s about 0 04 p er cen tpho sphorus, un der 0 05 sulphur, an d less than 1 p er cen t silicon ;Similar ore bodi es are kn own at Okampad an d Badampahar .

The Sin ghbhum depo sit is bein g worked at Pan sira Hill and BuduHill , south - east o f Manharpur, on the Ben gal - Nagpur Railway . Itapp ears to be a part o f an iro n - ore ran ge formin g a defin ite horizonin the Dharwar rocks, an d extendi n g for some 40 miles in a sout hwesterly directio n from Sin ghbhum . En ormous quan tities o f ore

are beli eved to exist, but un til the supp o sed exten sion s have beendefin itely proved in depth by drillin g , n o estimate as to quan titycan be made .In the Chan da and Drug districts o f the Cen tral Provin ces

,

depo sits o f high—grade low-

phosphorus o re have been di scovered,but have as y et n o t been exten sively pro sp ected . The Mysore oresare

'

n o t o f great exten t . They are bein g worked ten tatively by theTata Iron an d Steel Compan y ,

for the Mysore Governmen t . .Highgrade low- pho spho rus ores exist in Goa an d Ratn agiri , probablyin con siderable quan tity but they have n ot as y et been proved indepth .

Al together the re serves of high -

grade ore already partly proved inIndia may be safely put at several hun dred million ton s

,an d the

pro sp ects are favourable fo r the existen ce of very much largerquan tities .

AUSTRALIA .

Little is kn own o f the iro n - ore resources of Australia exceptthat man y imp ortan t depo sits exist bo th n ear the coast an d inthe in terior . Some of these are at presen t bein g investigated inSouth Australia ,

Western Australia,Queen slan d,

an d Victoria .

A high -

grade ore is bein g worked in South Australia by theBroken Hill Proprietary Compan y at Iron Kn ob . The ore is carried

5 1 6 F. H. Hatch— The Iron Or e Supp li es of the Wor ld.

at low co st by water tran sportation to the Compan y ’

s ironworksat Port Waratah n ear Newcastle in New South Wales

,where it

is smelted to basic p ig for o p en - hearth steel manufacture . Workat Iron Kn ob is at presen t restricted to quarry in g , an d the outputis about to n s p er an num . No figures as to '

reserves are

available .CONCLUSIONS .

Summarizin g the estimates fo r the great ore—fields o f Europ eand the Americas (n amely , the Un ited States, Cuba,

Newfoundlan d,

Brazil, Scandin avia , Cen tral Europ e , the Un ited Kin gdom, Spain ,

an d North Africa) We arrive at the fo llowin g round figuresMillion ton s .

High -

grade low-

pho sphorus oreHigh -

grade pho sphoric o re s

Low -

grade o re s

To tal

Ano ther millio n should be added for the small ore—fields o f

Russia,Austria,

and“

Greece in Europ e, an d Chile ,Ven ezuela ,Mexico ,

an d Can ada in America ,makin g a gran d to tal for the two con tin en ts

o f million ton s, of which the equivalen t iron is mi llionton s, or, o n the basis o f a p ig

—iro n production o f 70 million ton s a

year, sufficien t to last over 200 y ears .

The resources o f the con tin en ts o f Africa,Asia ,

an d Australiaare un kn own ,

but it has been shown In the forego in g that importan tdeposits exist in South Africa

,Australia,

an d In dia ,an d others are

kn own,for in stan ce , in Chin a ,

Korea,an d Japan . Moreover, havin g

regard to the very large un explored areas of these con tin en ts theexisten ce o f great reserves as y et un discovered i s very probable .

. An in gen ious method suggested by SjOgren and used by Eckelen ables the iron—ore resources of the un kn own co n tin en ts of Africa ,

Asia,and Australia. to be roughly estimated o n the basis o f the

kn own resources o f Europ e an d America .

'

It is assumed that theresources o f these coun tries are likely to be in some prop ortion tothe areas, which , as the geo logi cal prin ciples in vo lved are the samein bo th cases

,is n ot to o un reason able an assumption for the p lirpo se

in view . The to n mile factor fo r the kn own con tin en ts works outat to n s p er square mi le . App ly in g this to the areas o f theun kn own con tin en ts we get a figure o f million ton s for thereserves, which,

added ‘

to the figure already obtain ed for European d America, gives a gran d to tal of millio n to n s for theworld’

s resources of commercial o re , in the sen se of the presen tday usage of the term .

On the who le adequate 1ro n ore supp lies fo r the chief smeltin gcen tres o f the world seem reaso n ably secure fo r a remo te future .On e fact , imp ortan t for themakers o f he matite steel , clearly emerges,an d that Is the relative scarcity of low-

phosphorus o re . Exceptin gthe great reserve o f the very highest quality ore in Brazil the kn own

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REVIEWS.

GEOCHRONOLOGISOHE STUDIEN UBER DIE SPA TGLAZIALE ZEIT IN

SUDFINNLAND . By MATTI SAURAMO . Bulletin de la Com

mi ssIOn Géo logique de Fin lande , No . 50 . Helsin gfors, 1918 .

HE exten sio n in to Fin lan d o f Professor De Geer’s method o f

obtain in g the time - values of the stages of glacial retreat is aneven t well worthy of n o te . Dr . Sauramo

’

s. memo ir deals with a

co n siderable area of Southern Fin lan d,bo th n orth and south of the

great Fin n ish en d- morain e kn own as the Salpausselka. This regionwas largely submerged ben eath the Late - Glacial or Yo ldia Sea,

thesedimen tation in which was con tro lled by the flo od waters from theretreatin g ice - sheet . The summer flo ods brought coarse san dysedimen ts ;the win ter co ld reduced the glacial outflow,

an d the fin ersilts an d clays were dep osited at this season . There has resultedan an nual lamin ation ,

which,stran ge to say ,

is so remarkably con

stan t over wide areas that co rrelation from p lace '

to p lace is possible .The me thod of correlation in troduced by De Geer, an d app lied byhim with such Sp ectacular success in Sweden ,

con sists in drawin ggraphs alon g the axes o f which are marked equal in tervals repre

sen tin g the y ears , an d erectin g ordin ates proportion al to the thickn ess o f the corresp o n din g lamin ae . The graphs of the differen tsection s can then be compared by slidin g them : over on e anotherun til a co in ciden ce is obtain ed sufli cien tly remarkable to establishiden tity .

The distan ces over which Professor De Geer effected thesecorrelation swere con siderable

,but it is more than surprisin g to learn

that they can be carried out with a fair amoun t o f success by directcomparison between section s some 200 miles apart o n o ppo siteSides o f the Baltic . Seven section s, which the author of the pap erun der reviewultimately fitted in tothe Fin n ish chro n o logy ,were sen tto De Geer without lo calities or o ther clue to their identification .

In the case o f five o f these he attempted a correlation with theSwedish record

,but failed in two in stan ces, wi th regard to one of

which he had expressed doubt . The remain in g three he p laced inthe correct relation to on e an o ther, in which they ultimately workedout in the Fin n ish reco rd,

an d dated two o f them with respect to thethird with an error o f less than five y ears in a thousan d .

A study o f the lami n ated clay s correspondin g to the stages of

halt in the retreat , the mo st imp ortan t of which are those markedby the . in n er and outer wreaths o f the Salpausselka, has renderedpossible very accurate estimates o f the duration of these stages,an d brought out clearly the fact that they are p eriods o f min imumsummer ablation . The coarse summer zo n e , in stead o f formin g thegreater prop ortion o f each y ear’s sedimen tatio n , is reduced to a

negligible thickness or disappears altogeth er . The halt is thus

Revi ews— The Rep ti les of the Karroo Formati on . 5 1 9

obviously due to a drop in the summer temp erature . A drop in themean an nual temp erature can n o t be deduced,

but is probable . Theimp ortan t p o in t is , however, that the halt is due to a temperaturechan ge , an d n ot to a chan ge in the precip itation or n ourishmen t o fthe ice - sheet . This con clusion ,

which was also reached by De Geerin Sweden

,is in itself very in terestin g , as it is obvious that a halt

might be con ceived to result from in creased precipitation o n thesn owfie lds

, producin g an active thrust forward o f the glacier fron t ,an d so balan cin g the margin al wastage; This, however, is o n lyin ciden tal to the main po in t

,which it is the o bj ect of this review to

emphasize, an d which app ears to be quite n ovel .When the successive p osition s o f the ice - margi n are laid down on

a map ,or

,more strikin gly still , when the rate of retreat is p lo tted

as a curve again st the y ears, it becomes apparen t that p eriods o f

halt in retreat were fo llowed in n early all cases by unusually rapidwithdrawal

, _which gradually in the course of ten or fifteen y earsreverted to the n ormal rate characteristic o f that stage of the retreatin gen eral . This do es n ot app ear to have been due to excessiveablation , for the summer sedimen ts in the lami n ated clay s correspondi n g to these p eriods of rap id retreat have n o exception althickn ess

,and Dr . Sauramo draws the con clusion that durin g the

co ld p eriod of the halt the ice - sheet had become thin n er an d so

y ielded more rapidl y at its margin ,on ce meltin g set In agaIn .

Here,then

,is addition al light on the climatic condition of the

halt - stages . Wastage was in progress durin g these p eriods, but wasn ot

,to an y great exten t, effected by the pro cess o f ablation . The

ice surfacewas bein g loweredby some agen t indep en den t of ablation .

There seems to be on ly o n e physical process that could accoun t forsuch a remarkable phen omen on ,

n amely ,direct evaporation from the

ice . This is, of course , well kn own to be physically possible , but it

has certain ly n ever be en appreciated by geo logists as an effectiveagen cy in glacial con tro l . If it be n ow admitted as a result of thiswork of Dr . Sauramo

’

s that such is the case, and that undersufficien tly low con dition s o f temperature the wastin g effects of

direct evaporation may become comparable with tho se of ablation ,or

po ssibly exceed them,such a co n clusio n must modify al l our n o tion s

o f the growth an d ultimate decay of ice - sheets .

W. B . WRIGHT .

CONTRIBUTIONS To THE KNOWLEDGE OF THE REPTILES OF THE

KARROO FORMATION . By Dr . E . C. N. VAN HOEPEN . An nalsof the Tran svaal Museum

,vo l . Vii , pt . 11 , 1920 .

THE authordescribes a n ew genus ofDin o saur from the Stormbergbeds, an d design ates itAristosaurus erectus . The an imal was of

small size an d highly sp ecialized . It shows adaptation to a bip edalmode of lo comotion . The humerus is relatively much shorter thanin o ther An chisauridae

,the fami ly to which it belon gs .

520 Revi ews— Geo logy an d Iro n Ores of Cu-

yu-n d Di str ict.

In a second pap er the ali thor gives an accoun t o f two n ew gen erao f Therop oda ; the bo n es ofvarious kn own sp ecies are also describedBoth pap ers are il lustrated by excellen t pho tographic reproduction s .

F . H. A . M.

NOTES ON THE GEOLOGY AND IRON ORES OF THE CUYUNA DISTRICT,

MINNESOTA . . By E . C. HARDER an d A. W JOHNSTON . Bull .660—A

,U .S . Geo l . Survey , pp . 26, with on e map . 19 17 .

IN its geo lo gical features the recen tly develop ed Cuyun a ran ge

stron gly resembles o ther“ iro n—producin g areas o f the LakeSup erio r region . As elsewhere

,the o res belon g to the pre—Cambrian

an d presen t the same typ es. of ore an d coun try ro ck . The regionis almo st en tirely covered by a thick man tle o f drift

,an d it is o f

great in terest to fin d that the discovery of iron - ore was en tirely diie tothe existen ce o f abn ormalmagn etic condition s . The o ccurren ce o fthese abn ormalities has lOn g been kn own ,

but iron bearin g ro cks

were first p roved by bo rin g In 1904, an d productio n began m 191 1 .

The . ro cks o f the region ,so far as kn own

,are gen erally con sidered

to be equivalen t to the Virgin ia slate of theMesabi district , butmuchmore detailed wo rk is required before this correlation can be regardedas p roved .

-

'They have been in vaded,after the prin cipal meta

morphism,by ign e ous in trusi on s, supp o sed to be ofKeween awan age ;

here and there are outliers of Keween awan lav'

as an d o f Cretaceoussedimen ts .

The iro n fibearin g ro cks are fo lded in to a comp lex series of N.E .

S.W. syn clin es an d an ticlin es, fo rmin g a south west exten sion o f

the Lake Sup erior syn clino rium ; the predomin an t dip s in bo thlimbs of the fo lds are to the south east . The o re - bodies are exactlysimilar in gen eral character to tho se o f o ther ran ges, Showin g a widevariation o f typ e . The

'

best quality y et kn own ,a soft blue haematite

from the Croft Mine,run s up ,

to 67 o r 68 p er cen t metallic iro n ,with

very low phosphorus the main part of the o utput co n si sts of ore

with 58 to 60 p er cen t iro n and runn in g up'

to 0 4 or 0 5 p er cen tpho spho rus .

R . H . R .

SOUTH AUSTRALIADEPARTMENT OFMINES . Min ing Revi ew,N0 . 31 .

Adelaide,1920 .

THIS half—y early vo lume co n tain s statistics ofmin eral p roductio nin the State. for the who le of 1919 . The gen eral results app ear

satisfactory , con siderin g the presen t in dustrial con ditio n s . Theserious diminution in the out put o f copp er has been to a certainexten t coun terbalan ced by the in crease in iro n - ore

,which

, for thefirst time , takes the leadin g p lace“ in value .Amon g the Sp ecial rep o rts tho se of mo st gen eral in terest are the

Second Summary Rep ort on the utilization o f Leigh Creek coalan d an accoun t of the man gan ese dep o sits workedb y the -AustralianMang an ese Compan y at _

Pern atty .1A Short account is also given

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522 Rep orts (12 Proceedi n gs— In st. Mi n in g an d Meta l lurgy .

an d jun ction terraces, was n ot clear as to the mode o f formation of

what he himself called the lateral terrace prop er ”

Under thathead he seemed to in clude (1 ) terraces with straight o r Slightlycurved

,n early parallel fron t an d back margin s, an d (2) terraces with

stro n gly curved back margin s con cave towards the river . ProfessorDavis

,elaboratin g an idea little more than suggested. by Miller,

p rop ounded in his pap er o n The River Terraces ofNewEnglan d a

satisfactory theory ,n o t so much of terrace - formation as o f terrace

p reservation . The lateral terraces prop er o f Miller, particularly(2) above— the mo st difficult o f al l to accoun t for - still requiredexp lan ation . Such terraces had eviden tly been Swep t out in the firstin stan ce by pron oun ced an d fairly p ersisten t bends , to which thecharacteristic curves o f their backmargin swas due . In the case of theDee , the river was n ot withdrawn by short - circuitin g acro ss the n eckso f the Spurs within the bends fo r the slop e of such terraces was, o nthe who le , towards, n o t away from the presen t '

course o f the river .

The con dition s determin in g the formation o f river islan ds and theirin corp o ration in the flo od-

p lain (were discussed in detail . It wasp o in ted out that every terrace o f an y exten t alon g the Dec was

traversed by a larger or smaller number of an astomo sin g ho llows,p lain ly former chan n els o f the river or o f bran ches o f it an d thatterraces o f al l typ es had been built up by the accretion of islan d toislan d through the desertion an d subsequen t partial obliteration(by flo od loam,

etc . o f secondary chan n els . The pro cessWas shownto have i llustration s elsewhere

,an d the prin cip le invo lved was n o

doubt o fwide ’

app lication in the case of rivers of fairly steep gradien twhose flo od -

p lain ,like that of the Dec

,was practically co exten sive

wi th their meander belt .3.

“A Rhomb Porphyry Boulder from the Glacial Deposits at

Bay o f Nigg , Aberdeen .

”

By Dr . Alex . Bremn er, Aberdeen .

The Rhomb Porphyry— a boulder weighin g 32 1b .

—was foun d'

15 feet above H.W.M.O .S.T . in a boulder bed,far to o coarse to be

called a grav ,el underly in g the Lower Grey Boulder Clay o f the

Aberdeen district (se e Tran s . Edin . Geo l . So c. vo l . x , pt 111 ,

p . The probable ways in which it might have reached thep lace where , it was found were discussed

,an d the resemblan ce

between the glacial sequen ce at Bay o f Nigg an d that on the Yorkshire coast was p o in ted out . This was the first record o f theoccurren ce of a Scan din avian boulder, i n situ in glacial deposits,o n the main lan d o f Sco tlan d .

INSTITUTION OF MINING AND METALLURGY .

October 21,1920

The Origin of Primarv Ore Dep o sits . By J . Morrow Campbell,D.Sc .

,F .G.S

The autho r commen ces at the period when the o uter silicate shellof the earth was mo lten . The primeval magma is regarded as havin g

Rep or ts aft Proceedi n gs— Corni sh I n st. En g i n eers . 523

been practically homogen eous an d con tain in g about 60 p er cen to f combin ed silica . All water was then in the atmosphere . AS

temp erature fell water an d'

ox ygen were absorbed, crust - formation ,

foun derin g , an d resorption wen t on for a lo n g p eriod, producin g a

flat temp erature - gradien t in the liquid . When the crust becamep erman en t, gran ite develop ed,

and below it basaltic magma lo n gremain ed liquid . At this stage the isostatic balan ce was adjusted .

Ore - min erals in large quan tity were given o ff at the surface of thegran ite , were denuded,

an d disp ersed in sedimen ts an d so lution .

This,with subsequen t absorp tion by basaltic magma

,is assumed to

have been in strumen tal in causin g the presen t erratic distribution of

primary o res .

Magmatic differen tiation is regarded as havin g been caused :bythe agen cy of silicic acid— silicon combin ed with hydroxy l— whichextracts p o tash alumin O - Silicate

, producin g a so lutio n immisciblewith an d lighter than amelt of basic felspars and femic mi n erals .

Eviden ce regardi n g the existen ce o f silicic acid in magmaticliquids an d elsewhere in n ature is recited .

The ultimate result o f the action of water on ro ck magmas is thatsilicates are comp letely removed and a residue o f ore - min eralsmagn etite , etc . .

— left .Vein fissurin g is held to have been brought about in an d abovebatho liths by the expan sive force due to the in crease in so lid sp ecificvo lume of various elemen ts . The effect o f this '

force appears in wavesas successive series o f fissures . These develop ed very rap idly ,

werein stan tly filled with magmatic mother- liquor

,and quickly sealed

by the dep o sit of so lids therefrom . It is argued that primary ore

mi n erals passin g up from magmas to vein s do so in silicic “

acidso lution that their dep osition is determi n ed bo th by lo ss o f heatan d reduction of pressure 1; an d that there are defin ite but n arrowlimi ts o f temperature between which each ore - min eral develops .

Reason s are given why the pn eumato lytic origin of tin an d

tun gsten ores should be rej ected .

CORNISH INSTITUTE OF ENGINEERS .

Sep tember 16 , 1920 .

On the Characters of some Corn ish Vein ston es . By thePresiden t

,Mr . E . H. Davison .

The pap er gives the results.

of the examin ation of a n umber of

Corn ish lodes . Those n ot at presen t bein g worked were represen tedby iso lated sp ecimen s from kn own p o in ts in the lode , while the lodesn ow workin g were systematically sampled down the clip .

The methods emp loy ed in cluded mi croscop ic and micro chemicalexamin ation as well as in some cases mechan ical an alysis . It wascon sidered that three typ es could be recogn ized which were relatedto the surface of the n earest gran ite mass .

524 Cor’

resp on den ce

1 . Quartz - wo lfram lodes . Little cassiterite , sulphides, or tou’

rma

lin e,characteristically n o chlorite . Upp er level of tin and tun gsten

zon e . Occurrin g in the slate or just in.the gran ite, at or n ear the

crest o f the mass .

Quartz - chlorite - wo lfram- cassiterite—mispickel 'lodes . Chlo ritepredominan t over tourmalin e . Cassiterite usually more thanwo lfram“ Sulphides common . Middle o f tin - tun gsten zon e .3. Quartz - tourmalin e - cassiterite lodes . Tourmalin e predomin an t .Wo lfram absen t . Sulphides absen t or subordin ate . Lower part o ftin - tun gsten zon e . Occurrin g in '

depth in the gran ite .It was also n o ted that if wo lfram was presen t in the lode , copp er

was absen t or subo rdi n ate . The detailed micro scop ic characters o f

the vein ston es were gi ven in tabular form at the en d of the paper .

CORRESPONDENCE.

PHYSIOGRAPHIC RELATIONS OF LATERITE .

SIR,— In reply to ProfessorW. ,M. Davis’s in quiry in the September

n umber o f this Magazin e , I should in the first place explain that mypap er o n Lateritization in SierraLeon ewas con cern ed essen tially withthe chemical an d min eralogical chan ges un dergon e by the di fferen treeks o f the coun try in the course o f their tran sformation . in tolaterite, an d o n ly to a min o r exten t with the relation o f the lateriteto surface forms an d physiographic o ld age . Nevertheless

,I am

indebted to Professo r Davis for directin g my atten tion to severaladditio n al p o in ts o f in terest .In Sierra Leon e as elsewhere in the trop ics, laterite is in gen eralbest develop ed o n surfaces of gen tle slope or low relief

,as the

fo llowin g examples from difleren tp arts o f the coun try will show1 . The Coastal Plain .

—~This p lain ,which alon g the in n er margin

rises to’

a height o f about 400 feet above sea - level , con sists o f

sedimen ts, probably of Pleistocen e age , which are still in process o f

lateritization . Lo cally on these sedimen ts there o ccur large baresheets o f laterite

,free from vegetation an d so il

,similar to those

described,by Mr . Morrow Campbell ,1 an d exp lain ed by him as due

to rap id'

growth o f highly ferrugin ous laterite this laterite .dimi n ishes the fertility of the so il , which , lo sin g the protection of

the dy in g vegetatio n ,becomes g radually washed a way by the

to rren tial rain s .

2 . The Crystallin e Rocks of the Lowlands — These rocks un der thefo llowin g condition s are in gen eral deep ly kao lin ized an d lateritized

‘

(a ) Where risin g as low hills above the sedimen ts o f the coastalp lain(b) On tho se un dulatin g areas in which the p lain merges alon g its1 Late rite

,its Origin , Structure , an d Min eral s Min in gMag ,

vo l . xvii ,19 17, p . 178 .

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526 Corresp on den ce— C. T. A. Caster .

gran ites ; these areas, which are quite bare except where coveredby o ccasion al clumps of grass, are remarkable in bein g quite fresh ,showin g n o sign s of weatherin g o r an y o ther kin d of alteration . T he

absen ce of laterite on such surfaces has been exp lain ed byMr .MorrowCampbell

, who has paid much atten tion to the con dition s underwhich ro cks become kao lin ized an d

'

lateritized in the trop ics . Thiswriter con siders that crystallin e rocks must be altered before theycan be lateritized

, and also that the alteration n ecessary , gen erallykao linization

,can

_

be produced on ly when the ro cks have been fora lon g time con tinuously in con tact with vadose water, i . e . in thezon e o f p erman en t saturation .

1 Accordin gly ,the fresh surface rocks

referred to above,n ot havin g been subj ected to such con dition s,

remain un lateritized .

F . DIXEY .

UNIVERSITY COLLEGE, CARDIFF .

October 4 ,1920 .

AN UNDESCRIBED SPECIES OF TROCHILIOPORA .

SIR,— '

I desire to draw atten tion to a ban d of Chalk in Sussex,about 10 feet thick

,n ear the base o f the zon e o f Micraster cor

anguinurn ,in which an undescribed Po ly zo on belon gin g to the genus

Trochi liop ora is very common .

‘

As this fossil app ears to be con fin edto the said ban d of Chalk

,an d also owin g to its abun dan ce , it has

p roved to be a very useful lo cal zon al guide fossil . The exactposition in which it occurs in the Micraster coranguinuni zon e is asfo llows

Lower fourth Stron g M . coran guin um tabular flin t ban d .

o f zon e of (Chalk , about 35 fe et .

M icraster Chalk with Trochi l iop ora sp .,10 fe et .

coran guin um. Chalk , about 17 fe et .

Chalk of zon e of Ill icraster' cortestudin arium.

I propo se to call the 10 feet o f chalk referred to the Trochi liap ora bed

The genus Trochi liop ora has been described by Professor J . W.

Gregory in the GEOLOGICAL MAGAZINE ,1909 , p . 65, an d also in the

British Museum Catalogue of Cretaceous Bryo zoa, vo l . ii , p . 265 .

The sp ecies above referred to resembles T . humei , Gregory , but its

body tap ers to a much fin er stem than the stout blun t stem of thelatter sp ecies .

The Trochi liop ora bed is rich is Po ly zoa,it hav mg y i elded some

rare an d in terestin g forms .

CHRISTOPHER T . A . GASTER .

LEWES, SUSSEX .

October 4 ,1920 .

GEOLOGY OF THE NINGI HILLS.

SIR,— Maj or Williams’ paper on the geo logy o f the Nin gi Hills

o f Nigeria in the October number is very welcome . It indicates n ot1 Morrow Campbe l l;op . cit . , p . 123.

Obituary— S. L. Torn quist. 527

on ly an in creasin g in terest by the min in g commun ity in the geo lo gyof the Nigerian tinfie lds , but also ,

I hope,an in creasin g di sposition

to publish geo logical observation s thereon . Maj or Williams,how

ever,will agree that‘ in View of lo cal con troversies it is imp ortan t

that facts an d co n clusion s should be correctly stated an d deduced,

an d I may therefore p erhaps be allowed to make the fo llowin gremarks upon hi s pap er .

Maj or Williams makes n o men tion of the fact that I mapp ed an d

described in 19 11,in my Geol ogy and Geography of Northern

Nigeria the y oun ger riebeckite grani tes of Nin gi , Kila,an d

Fagam,with which a portion o f his paper is con cern ed . Of the

coun try between Buj i an d Nin gi , I have little person al kn owledge ,but fromwhat I have gathered i n con versation wi th capable observerswho have repeatedly traversed it, and from what I kn ow of

the adj o ini n g parts o f the tin fields,I feel sure that there are there

n ot exten sive outcrop s o f an o lder rieb eckitic Sabon Garri gran ite ,but a number o f outcrops o f y oun ger riebeckite - gran ite pro j ectin gthrough o ldermicaceous gn eisses of various typ es . In spite of theassertion to the con trary in the app en di x o n p . 446 , the petrographicaldescrip tion s do n o t con firm the hyp othesis of an o lder series of

in trusion s “s pecially characterized by p erthite , riebeckite

,an d

aegirin e Of the section s quoted in supp ort No s . 106, 108 , 1 10 ,

C.C. 3,an d C.C. 4 con tain n o p erthite , riebeckite , or aegirin e No . 1 13

is valueless as eviden ce No . 1 15 is said o n on e page to be shghtlycrushed an d on an o ther to show n o Sign o f crushin g an d to

belon g to the y oun ger series while No s . 100 and 105 are simplysection s of n ormal y oun ger gran ite .It would also be in terestin g to kn ow howMaj orWilliams arrives at

his belief that the youn ger gran ites of\Nigeria are o f Meso zo ic age .

It may be on accoun t o f the relative freshn ess of their outcrops, asin the case of the Tertiary gabbro dyke o f Keffi Filani . In an ycase the distin ction o f Archaean an d Meso zo ic soda -

gran ites inNigeria can n ot be con sidered e stablished,

while - the gen eralizationthat tin is on ly found in grani tes that con tain riebeckite is trueon ly in the sen se that tin ston e is asso ciatedwith the y oun gergran ites ,which may or may n ot carry riebeckite .

J . D. FALCONER .

LONDON .

October 13, 1920 .

OBITUARY.

Sve n Le o n hard To rnquist, Ph.D

BORN MARCH 6 , 1840 . DIED SEPTEMBER 6 , 1920 .

THE study o f Graptol ites has in the last few y ears suffered the lo ssof some o f its veteran workers, an d to the n ames o f Hopkin ‘

son an d

Lapworth must n ow be added that o f the Swedish geo logist,S. L . Ternquist . Born at 'Uddevalla in 1840, he proceeded in due

Obituary— J.

“

S. Gei ki e—QC. CuMo o

course to the Un iversity o f Lund,where Otto To rell was lecturi n g

o n geo logy ,an d In 1865 obtai n ed the degree o f Ph .D . o n the stren gth

o f a pap er on the Ordovician beds o f Fagelsan g . I- n 1867 he becamereader at the seco n dary Scho o l o f Gefle , an d i n 1882 was tran sferredto Lun d,

an d at bo th p laces devo ted his leisure to the study o f theOrdovician an d Silurian ro cks in the n eighbouring districts . In

1892 his careful researches o n the o rgan ization o f Grapto lites bythe .method of grin din g down sp ecimen s preserved in pyrites shedmuch light o n the structure o f these fo ssils. He was elected ForeignCorresp on den t o f the Geo logical So ciety o f Lon don in an d

became a Fo reign Member i n 1900 . The title o f Professor was co nferred on him In 1902

,an d i n 1905 he resign ed his teachin g duties ,

but con tin ued to reside i n Lund till his death , which to ok p lace aftera few day s

’ illn ess . Up to the last'

he preserved his vigour of min dan d body ,

an d his kin dly n ature,ever ready to assist his fellow

wo rkers with his wide . experien ce an d kn owledge , en deared him to

al l his frien ds, while his n umerous pap ers o n the Lower Palwozo icbeds and faun as o f Dalecarlia an d . Scan ia form a valuable con

tribution to sci en ce .

Jam e s Som e rvil le Ge ikie.

BORN 1881 . DIED 1920

MR . J . S. GEIKIE, .Son o f Professor James Geikie an d n ephew o f

SirArchi baldGeikie , died recen tly i n Born eo from septic p n eumon ia,

at the early age Of 39 . As the in heritor o f a go od Share of the ability ,

o f his fami ly , he gave promise o f a highly successful career as a

min in g en gin eer, havin g already carried out techn ical Work of muchimportan ce at the Bau go ld mi n e in Sarawak an d elsewhere . Hisgreatest in terest , however, was in -

,geo lo gy in which scien ce he gavepromi se o f excellen t future work . His lo ss wi ll be sin cerelymourn edby man y to whom he had en deared himself by the simp licity an d

stren gth of a fin e character .

Charle s Cl ifto n Mo o re , F.I.C .

BORN 1862 . DIED 1930 .

MR . C. .C. MOORE,who died on August 1 1 last , was well kn own in

bOth sei en tific an d commercial circles In Lan cashire an d Cheshire .

He was for some time en gaged In chemical work at St. Helen s, an dfor thirteen y ears with Brun n er, Mo n d Ltd . Afterwardshe foun ded the imp ortan t firm o f Charles Mo ore CO .

,Ltd .

chemicalman ufacturers . In sp ite of a busy commercial life,he was

alway s ,much in terested in geo logy ,

an d was Presiden t of theLiverp o o l Geo lo gical Society . His pub lished papers, in the Proceedings o f that Society ,

chiefly dealt with the vo lume - relation s o f

ro cks, an d comprise man y very compl ete an aly ses o f ro cks As a

man ofwide kn owledge an d gen ial disp ositio n he will be much mi ssedby those who en j oy ed his acquain tan ce .

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THE FLOW ER ING PLANTSOF AFR IC A .

AN ANA liYT l C -AL KEY TO THE GENERA OF AFRICAN

PHANEROGAMS .

BY FR . T HO NN ER .

xy l an d 6 4 0 Pag e s , 1 5 0 P l ate s , 1 Map . (310111 .

PR IC E 1 5 5 . N ET .

TABLE O F BR ITISH STRATA .

COMP ILED BY

HE N RY W O O DW A R D . I_'

L . D F . R . S F . G . S .

HO RA C E B . W O O DW A'

R D .

'

F .R . S F .G . S .

5 / n et. Fo lded in book form , n e t.

L o n d o n D U LA U C O . , L td .

34 3—3 6 M a r g a r e t S tre e t , C a v e n d i sh Squ a r e , W . 1 .

SC IENT IFIC BOs a n d SER IALS .

JOHN WHELDO N CO . have th e l arg e st sto ck ffi the c oun try o f Bo oks in a l l

d e p artme n ts o f Scie n ce an d Natura l Hi story ra l so Tran sactio n a an d Journ al s o f L e arn edSo cie tie s . e tc . , in se ts , run s , an d si n g l e vo lume s or numbe rs .

Li b ra r ie s o r Sm a l l Pa rc e l s Pu rc h a s e d .

SPECIAL CATALO GUES Ge o lo g ica l . Bo tan ica l . Zo o lo g ica l , En tom o lo g ica l .

O rn itho lo g ica l . Che m ica l , A g ricu l tura l , Ga rde n in g , e tc . , 2 d . e ach. p o st fre e .

cs GREAT QUEEN STREET , KINGSWAY, LONDON“

, w.c .

Te lephone : GERRARD 1412 .

Al l Commun icatio n s for the EDITOR should be addres sed to

R. H. RASTALL, Esq., M.A .

, Christ’s Co l leg e , Cambridg e .

Al l l e tters for Dr . H . VVOODWARD , may be sen t to

Tudor Cottage ,. I

QIay Hil l , Bushey , Herts.

Bobks and Sp ecimen-s to be addv'

esSed'

to the Edi tor as usua l , caré of

MESSR81'

DUL'

A'

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I

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,

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- fi l n a l M un

(mon th ly 30 1111 1911 of (Eco l o g y .

\VITH “’HICH IS INCOR PORATED

T HE G E O L O G IS T .

D ITED BY

HENRY VVOODVVARD,LL .D . ,

F .R . S .

R . H. RASTALL , M .A .

ASS ISTED BY

PR OF . J . W . GREGORY . D . SC -F R . S . SLR JETHRO J . H . TEALL , Sc .D . , FR S .

F . H . HATCH , PH .D ., PR OF . W . W . WATT S . Sc .D . , F .R . S .

PR OF . J . E . MARR . SC .D F .R . S . HENRY W OODS , M A . , F.R . S .

A . SM ITH WOODWARD . LL .D F .R . S .

DECEMBER,19 20 .

CONTENTS :

P a g e ORIGINAL ARTICEES Pag

EDITORIAL NOTES 529 A The ory o f the - Marg in al DriftORIGINAL ART IOLES .

BYW B . WRIGHT - u

No te s o n theGen us Sp hazrocomjphc .

ByW . B . R'

. KING. (Plate XIII . )“M EW S

North Am erican Sp ecie s o f E the An In troductio n to 55

fridgma . BY D . K . GREGER .

Excavation s in Turke stan 55

(Plate XIV. )I

A new Ammo nite Ge n us fromREPORT S AND PROCEEDINGS '

Charmouth . By L . F . SPATH . Min eralog ical Socie ty(Plate 538 Edin burgh Ge o logical Socie ty

Min eral Comp o sition o f Fe n lan d

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530 Edi tor ia l Notes .

p icked up o n the surface , to a large exten t by Dr . an d Mrs . Sturgean d the se r es from Warren Hi ll

,High Lodge , an d Elveden are Of

the highest imp ortan ce . Hun dreds Of Drift imp lemen ts come fromgravel pits in the Thames valley n ear Dawleyan d quan tities from o ther well - kn own sites

,such as Swan scombe ,

Farn ham,Dun bridge , Southampton ,

Savern ake Fo rest , Bedford, an dBroom . A large “quan tity had been acquired from Mr . Worthin gtonSmith

,mostly found in n orth - east Lon don ; an d o ther co llectio n s

made by Can on.

Greenwell an d Messrs Green hill,Allen Brown ,

Simeon Fen ton , Robert Ellio t, and Thomas Bateman werein corp orated .

The foreign sectio n,

is also very rich,the en tire con ten ts Of man y

Fren ch caves havin g been o btain ed fromM. Reverdi . Chief amon gsuch specimen s is a So lutre blade from the hoard found at Vo lgu

in the Dep t . - Sa6n e - et - Lo ire ; and the Fren ch Drift an d Neo lithicseries are well selected . Scan din avia ,Western an d Southern Europeare adequately represen ted,

an d there is a large co llectio n from the

Swiss lake - dwellin gs . An ample Egyptian series con tain s some o fthe best flin t wo rk kn own , an d there are hun dreds o f excel len texamp les from America , South an d East Africa ,

an d Madras .

1

WE have received a copy o f the first n umber o f a n ew p eriodi cal ,The Min ing

"

Electrical Engin eer, which is to be the o fficialj ourn al o f the Asso ciation o f Min in g Electrical En gin eers thisbody has n ow had a useful existen ce o f eleven y ears , an d it hasn aturally felt the n eed o f a defin ite o rgan of op in ion ,

to p lace beforethe world a reco rd o f the work don e by the Associatio n ,

an d to co llectin formation as to the gen eral p rogress o f electrical en gin eerin g as

applied to min es . The co n ten ts o f this number are n aturallymain ly o f a techn ical n ature

,an d there is n o t very much bearin g on

geo logical question s . Nevertheless,the co n n exion between min in g

an d geo logy is so clo se that we welcome this additio n to the literatureo f the subj ect . The gen eral get - up o f the j ourn al , which is profuselyillustrated is excellen t

,an d we wish it a successful career .

AT last the Geo logical So ciety o f London (fo llowin g the earlierexamp le o f the Geo logists ’ Association ) have reso lved to exp en da sum o f £500 from the invested fun ds of the Society to

provide the mean s n ecessary to carry o n scien tific publication s,and a special gen eral meetin g will be held on December 1 ,

1920, at p .m .,in order to Obtain san ction to carry out this

Obj ect . Havin g regard to the great in crease in the co st Of prin tin gand paper sin ce the War

,n o Fellow Of the So ciety can doubt the

wisdom of this recommen datio n of the Coun cil . In addition to the1 A summary descrip tion in Fren ch o f the who l e co l lection was prin ted for

the me e tin g o f the In tern ation al Con gress o f Anthropo logy an d PrehistoricArchaeo logy wh ich met at Mon aco in 1 906;

Edi tor ia l Notes . 531

above proposed p rovision o f fun ds, Fellows are remin ded that,after

the comp letion of vo l . lxxvi they will n ot be en titled to receivethe Quarterly Journ al regularly un less a subscrip tion at the rate o f103. p er vo lume is paid in advan ce

,alon g with their an nual con tribu

tio n to the Society . Those Fellows who do n o t require the completeseries can obtain separate parts at the price of 33. each

,if applied

for within on e y ear o f the date of issue .>l<

WE have been in formed that a prop osition is on fo ot— between theTrustees o f the British Museum and the Treasury— to revise thep resen t scal e Of salaries for assistan ts n ow en terin g the

_

British

Museum so as to ren der them more in accordan ce with tho se ino ther bran ches Of the public service an d remove the difficulty whichat p resen t p reven ts man y able men

,with Un iversity train in g , from

o ffering themselves as can didates for vacan cies n ow actually existin gin the staff of theNaturalHisto ry Bran ch . We trust that

, in additio nto a larger in itial salary about to be Offered to n ew men who mayapp ly for these vacan t p o sts, the salaries o f those Older men n ow

up on the staff will also be in creased so as to ren der them more inin accordan ce with the chan ged circumstan ces o i - l ivin g in 1920—1 ,from which all p erson s with fixed yore—War in comes are sufferin gmo stly without hop e o f relief .

s:

THE n in ety—seven th an nual rep ort o f the Whitby Literary and

Philo sophical Society con tain s, amon g o ther matter o f local in terest,an excellen t article by Mr . J . T . Sewell , en titled Notes o n theGeo logy of Whitby San ds The rap id erosi on of the boulderclay cliffs west of Whitby 1s kn own to man y ,

and even the writerof the presen t n o te , i n the course o f a n otvery long life , ha s witn essedsome remarkable chan ges . But the variatio n s that have taken p laceo n the beach are p erhaps Of equal in terest , an d much more di fficultto detect . Mr . Se ‘well has made minute an d detailed observation son the sp o t for thirty y ears, recordin g an y exp o sure of rock due totemp orary removal o f the san d an d gravel by tides, waves, an d

curren ts,esp ecially durin g storms

,an d he has thus accumulated an

un rivalled acquain tan ce with the details Of this particular stretchof foreshore . Some useful in fo rmatio n was also acquired durin g thebuildin g o f the p ier exten sion s . The results are p resen ted in a coup leof large—scale maps, 12 in ches to the mile , which show,

amon go ther thin gs, that bo th p iers rest o n Lias shale . It is also veryin terestin g to fin d that Mr . Sewell ’s Observatio n s lead him, withapparen tly go od grounds, to doubt the existen ce of an y fault inWhitby Harbour .

.This pap er is an excellen t example of the way

in which the lon g - con tinued and careful Observation s of a geo logistlivin g on the sp o t may serve to correct the hasty gen eralization s oftho se n ot p ossessin g the lo cal kn ovvledge so n ecessary in work of

this sort .

ORIGINAL ARTECLES.

Sedgw ick Muse um'

No te s : No te s o n the G e n us

Sp ha e ro co ry p he .

By w. B. R . KING,M.A .

, F . .G S

(PLATE XIII . )

R . F . R . COWPER REED,in a pap er en titled No tes o n the

Af fin itie s of the Gen era o f the Cheiruridae p o in ts out thatSp

-hcerocorgphe belo n gs to the Che iruridee,while Sian rocephalas,

’

which has at first sight some sup erficial likeness to it,bet/longs

probably to the En crinuridaeSome addition al light has been thrown o n to this subj e

7

e/ by therecen t discovery o f a comp lete sp ecimen Of Sp kcerocoNg/ai/ i e i n theAshgill

‘

ian beds o f Norber Brow, Austwick, n ear Settle , by Mr . T . H.

Tho rn eycro ft, _o f Pembroke Co llege , Cambridge . Mr . Thorn eycro fthas kin dly presen ted the sp ecimen to the Sedgwick Museum . Thesp ecimen ,

which i s referable to Sp hcerocoryp lie thorn son i Reed,although somewhat compressed an d crushed laterally by the“cleavage ,p o ssesses al l the characteristics o f the sp ecies, but the chief p o in to f in terest is that the hyp o stome is preserved in p lace , an d wasfoun d in side the swol len fron tal part Of the glabella . The hyp ostomean d material fillin g the glabella broke away an d remain ed o n thecast ’’ side o f the sp ecimen . This app ears to be the first hyp o stome

defin itely referable to a sp ecimen o f this gen us . The hy po stome o fStaarocep kaln s 1s also ra

,re but o n e is figured by Salter, an d this 1s

preserved In the British Museum .

Novak 3 has shown that hyp ostomes are o f con s1derable use indetermin in g the family relatio n ship o f various gen era,

and his

con ten tion seems to - ho ld go od in this case also . It . may be as

well , therefor-e,to describe the hyp o stome Of Sp kcerocorgp he thorn son i

which Mr. . Thorn eycro ft foun d associated with the comp lete individual an d compare it with that Of o ther Che irurids an d

Staurocep halus .

The hyp ostome is slightly smaller than the swo llen fron tal part o fthe glabella ,

sin ce it was foun d pushed in to it without co n tortio n .

The gen eral outlin e i s square,formed Of a large cen tral , raised,

ellip tical p o rtio n surroun ded by a deep wide gl o ove an d raisedn arrow margin . The an terio r margi n i s n o t well preserved in

this sp ecimen ,but app ears to be slightly curved 111

'

outlin e an d to1 GEOL. MAG 1898, p p . 206—14 .

2 British Tri lobite s.

- 83, p l . vii , fig . 1 1 .

Ottomar Novak, Studie n an Hyp o stome n bOhmische r Trilobiten

K e n . Behm Ge se l lschaft cl e r iVissen schaften ,Prag 1879 86 .

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534. W. B . R. Ki n g— Notes on the Gen us Sp heer ocor yp he .

risin g blun t trian gular raised cen tral p ortion p ossessin g two markedkn obs, rather below the cen tre . The an terior part is n early flat ,with o n ly

'

slight un dulation s . The g en eral outlin e o f the Who lewould be trian gular .

It Is difficult to fin d an y family with a similar typ e of hyp o stome ;certain it is that it is far from the Cheirurid typ e, but i t must alsobe admitted that very little resemblan ce can be seen between itan d the n ormal En crinurid type, with its peculiar and strikin gcen tral ton gue - like an terior pro trusion .

A study o f the hy po stome o f Staurocephalus therefore confirms

the vi ew that it should be remove d from the Cheiruridae,but do es

n ot seem to in dicate that it should be put in to the En crin urideeun less it bran ched o ff from some very early form before thecharacteristic fron tal ton gue was develop ed . However

,al l figures

o f En crinurus or Cybe le which show the hyp o stome have this ton guewell develop ed . If

,however

,Staurocep halus is barred from both

the Cheiruridee and En crinuridae it is difficult to fin d a family inwhich to p lace it .It may n o t be out o f p lace here to study some po in tsin co n n exionwith the g en eral structure o f Sp li cerocom/pke ‘

an d fo rms o f similargen eral app earan ce . As the specimen from No rber Brow,

althoughmuch compressed laterally ,

shows all the details o f the orn amen tationclearly , it was decided to draw a restoration

,takin g the details

largely from the No rber Brow sp ecimen , but the gen eral outlin efrom some o f the Girvan sp ecimen s, esp ecially from a n early com

p lete'

sp ecimen in the British MuseumThe restoration (Plate XIII ) i s in ten ded to brin g out some of the

more strikin g features o f 81072097ocorgphe thomson i Reed . A detaileddescrip tion of the sp ecies is given by Dr . Reed in his Girvan Trilo bitesmon ograph .

1 To this there is n othin g to add,but a po in t which

o ccurs to a worker o n Lower Palaeo zo ic Trilobites, is that wheniden tify in g sp ecimen s o f this sp ecies it should be born e in min dthat the usual type o f pygidium is that shown in the restoration ,

2withapparen tly on e short an d on e lon g sp in e o n each side o f the axis .

From the fOI ego in g n o tes there would seem to be little realsimilarity between Sp hcewcorgp he an d Staarocepkalas ; the on lycause o f the con fusion which arose between these two gen era was themarked swellin g o f the fron tal part o f the glabella . This swellin gis p resen t in several o ther gen era , particularly Deiphon ,

probablya direct descen dan t of Spheemcorgpke , an d also i n the p eculiarAustralian gen us On gcop gge described by Dr . H. Wo odward .

3

Even some sp ecies o f Phacop s (s . s . for in stan ce P . cep halotes Corda

fromEtage G. o f Bohemia,show con siderable swellin g o f the fron tal

parts of the glabella . The origin an d use of this p eculiar lin e o fdevelopmen t seems to be rather obscure , but the “

subj ect is touchedup on by Dr . L . Do llo 4

in regard to Deip hon ,where he attributes the

extremely modified form to extern al influen ces con n ected with itsmode Of life .

N,B .

—,For fo o tn o te s see p . 538 .

GEOL . 1 920 .

PLATE XIII .

RECONSTRUCTION SPHZEROCORYPHE THOMSONI REED .

[T o face

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536 D. K . Gr eg er— N . Amer i can Sp eci es of E1her idg i n a .

selected for illustration,from the Fife sp ecimen s in hand,

an examp leattached

'

to a fragmen t o f gastrop od shell,sin ce this sp ecimen shows

bo th valves, in their n atural p osition ,an d o ther features in an

excellen t man n er .

'

ETHERIDGINA‘ RADICANS (Win chell) . (Pl . XIV,Figs. 4

1866 . Oran ia radica-

ns Win che l l . Ge o l . Rep t . Lowe r Pe n in sula o f Michigan ,

Ap p e n dix , p . 92 .

1890 . S iropha los ia rafl icans Be echer, A1n er . Journ . Sci .,vo l . x l , p . 240 , p l . ix ,

fio s . l 4—17 .

1892 . s . i i dican s 1: Clarke ,Palaeon t . New Yo rk, vo l . viii , p t. 1

, p l . v ,

figs . 27 - 30 .

I have seen but three imp erfectly preserved examp les of thissp ecies, from the limeston es of the Hamilton (Devoman ) from thevicin ity“

of Alp en a ,Michigan . Their con ditio n is such that sp ecific

characters are almo st obliterated . Beecher andHall Clarke have ,however

, given amp le illustratio n of the characters o f the sp ecies ,an d figures o f these authors are here reproduced .

ETHERIDGINA KEOKUK (Beecher) . (Pl . XIV, Figs . 9

1890 . Strop lzalOs ia keokuk Be eche r Ame r. vo l . 111, p p . 244—5

p l . ix ,figs . 1

1892 . S . kcoku/c Hal l Clarke , Palaeon t . New York , vo l . viii , p t 1, p l . xviia

fig s . 5 - 7 .

1014 . S . keokuk VVe l le i ,Mississipp ian . Brachiop oda ,

Mon ogr . No 1 , 111111 0 13

Geo l . Surv ., p . 145

, p l . xviii figs .

—18

This sp ecies is fairly abun dan t in the Crawfo rdsville Shale(Mississipp ian ) of In dian a, mo st frequen tly foun d attached to

Platgceras and co rals,also occasion ally foun d 0 11 the co lumn s o f

crin o ids,which are abun dan t in the shale . I have reproduced the

origin al figures of Beecher an d o n e by Hall Clarke .ETHERIDGINA SCINTILLA (Beecher) . (_Pl . XIV,

Figs . 12

1890 . Strop halosia sci n ti l la Be e cher, Amer Journ . Sci , vo l . x 1, pp . 243—4

p l . ix,figs . 10—13.

1892» S sci n ti l la Hal l Clarke Palaeon t . New Yo rk, vo l . viii, p t . 1, p l . v ,

figs . 32 - 4 .

1908 . S scin tilla Rowl e y ,Missouri Bureau of Ge o l . , vo l . viii , 2n d ser .

, p . 76;

p l . xvii figs . 26—9 .

19 14 . S . sci ntil la We lle r, Mississipp ian Brachiop oda , Mon ogr . No . 1 , Ill in o is

Geo l . Surv . , p .. 144 , p l . xvii i,figs . 19—23.

The y oun gest examp le of this species I have found is subcircular;and has a diameter o f 0 4 mm .

,the brachial valve is gen tly con vex ,

hinge f lin e an d beak very obscure . Sp ecimen s of 1 0 mm . in

diameter are slightly tran sverse, with well defin ed hin ge lin e an dless Obscure beaks

,the brachial valve gen erally exhibits on e o r

two well defin ed growth - lin es At this stage i n the developmen to f the shell the p edicle valve is closely cemen ted to the host, thehin ge lin e and beak o n ly bein g raised above the level o f the fron tand sides However

,up on reachin g maturity ,

or approximately2 5mm, In diameter, a trail begin s to form by the abrupt upward

D. K . Gr eg er— N . American Sp eci e-s of _Etlzer idg i n a .

”

537

deflection of thean ter10 1 marginso f thep edicle valve an d a thicken in gor p ilin g up o f the shell lay ers alon g the margin s o f the brachialvalve . With the upward deflection o f the an terior an d lateralmargin s o f the p edicle valve , a n umber o f irregular , ho llow , sp in elike digitation s form aroun d the margin s Of the p edicle valve andcon tin ue to grow outward, closely adherin g to the surface o f thehost . When the size o f the ho st 1s small

,as in the case o f a small

crin o id co lumn,the digitation s in fo llowin g the surface app ear to

clasp the ho st, but I cantD

scarce ly attach an y morpho logic sign ifican ceto the fact .

ETHERIDGINA INOONDITA n . sp . (Pl . XIV,Figs . 16

Shell min ute,seldom attain in g a diameter greater than 25 mm . ,

breadth somewhat greater _than len gth ; very irregular in outlin e .

Pedicle valve cemen ted to foreign obj ects an d con formin g to theirsui face ; area o f attachmen t con fin ed to the visce 1 al region beakfree an d slightly raised . An terior an d lateral margin s of the valvedeflected upwards at maturity an d formin g a trail . Brachialvalve flat or s omewhat convex

,excep t alon g the an terior margin s

here a rim is formed where the edges co n form to the up turn edmargino f the p edicle valve . Hin ge - lin e as lon g as or slightly shorter thanthe greatest breadth of the shell a lin ear cardin al area , delthyrium ,

an d well - develop ed teeth are presen t . Sp in es variable in numberan d confin ed to the margin s of the p edicle valve .This in terestin g little sp ecies is foun d in the Elmdale Formation

(Pen n sy lvan ian ,in the vi ci n ity of Beaumon t an d Cambridge ,

Kan sas, attached to the larger brachiop ods o f the faun a . It occursless abundan tly in the Kan sas City Formatio n (Pen n sy lvan ian ) ,in Jackson and Grun dy Coun ties, Missouri .Ho lotyp e : the origin al of Fig . 16, from Beaumon t, Kan sas(author’s co llection ) .

ETHERIDGINA SPONDYLIFORMISWhite& St . John . (Pl . XIV,Fig .

1868 . 4u losteges sp o ndy l iforrn is Wh1te St. John , Tran s . Chicago Acad .,

vo l . 1, p t . 1

'

p . 1 18 , te xt fig . 2 .

19 15 . Strop halosia sp o n vl yl ifor in is ? Girty , Bulletin 544 , U .S . Ge o l . Suq

p . 80, p l . x , fig . 8 .

I kn ow this in terestin g little sp ecies o n ly from the descrip tion and

figure given by the autho rs , and its relation ship to the sp ecies herediscussed is in ferred who lly from a study of the descrip tion .

Dr . Girty has figured an d referred to this sp ecies a very obscureSp ecimen from theWewoka Formation (Pen n sy lvan ian ) ofOklahoma .

Hall Clarke figure a Strophalosia sp on clg liformis vo l . viii, p t . 1,

p l . xviia ,figs . 25—6 . This is a true Strop lialosia ;it is a rare sp ecies

in the Kan sas City fo rmation . All sp ecimen s o f the sp ecies in mvco llection show a misshap en and twisted pedicle beak , and

,in :

variably, a cicatrix of attachmen t .

538 L . E. Sp a th— A n ew Ammon i te

'

fr om Charmou th.

EXPLANATION OF PLATE XIV.

FIG .

l . Etheridgin a comp lectcn s (Ethe ridge ) . x 4 . View of p edicle valve , after

Ethe ridge , 1876 .

2 . Id . x 4 . View of p edicle val-ve , afte r Etheridge ,

1878 .

3. 1d . x 4 . View o f con j o in ed valve s, figure by Grege r from Fife shiresp e cimen .

1

4 . Etheridgin a radican s (Win che l l ) . x 2 . In terio rs of two p edicle valve s

after Be e cher .

5 . Id . x 2 . View of sp e cimen with con j o in ed valve s , after Bee cher .

6 . Id . x 2 . View of p edicle valve , after Hal l Clarke .

7 . Id . 3. View of con j o in ed valve s, after Hall Clarke .

8 . 1d . x 3. View of p edicle valve ,after Hal l Clarke .

9 . Etheridgin a Iceokuk (Be echer) . x 2 . View of con j o in ed valves, afte r

Hal l 85 Clarke .

10 . Id . x 2 . View of p edicle valve , after Be echer .

1d .. x 2 . View of sp e cimen with co n j o in ed valve s, after Be eche r .

Etheridgin a scin ti l la (Be e cher) . x 4 . View o f p edicle valve , after

Hal l Clarke .

Id . x 6 . View of p edicle valve ,after Hal l Clarke .

1d . x 3. View of sp ecimen with co n j oin ed valve s ,figure by Grege’

r

from sp ecimen from ty p e- lo cal ity ,

Louisian a, Pike Coun ty ,Mo .

15 . Etheridgin a ? sp ondy liforrn is White St . John . Copy o f the origin alfigure .

16 . Etheridgin a in con dita sp . n ov . x 4 . Ho lo typ e . View of p edicle valve

sp e cimen from Beaumon t, Kan sas .

17 Id . x 4 . View of p edicle valve , sp ecimen from Cambridg e , Kan sas .

18 . Id . x 4 . View Of p edicle val ve , sp ecimen from Kan sas City , Me .

On a New Ammo n ite Ge n us (Day ice ras)from the Lias o f Charm o uth.

'

By L. F . SPATH,M.Sc.

,F . .G S

(PLATE XV . )

THE fo llowin g accoun t is based on the six sp ecimen s recorded byDr .

_

W. D . Lan g in his pap er o n The Ibeat- zon e at Charmouth ,and its relation to the Zo n es n ear it 5

After men tion in g theo ccurren ce

,in the top of the zon e, o f an apparen tly n ew

Po lymorphitid,Dr . Lan g added the fo llowin g fo otn ote A

strikin g form,3 to 4 in ches In diameter

,with n umerous, very thin

costae . Two sp ecimen s were foun d (n ot in p lace) in the win ter,1915—16, by Lieut . Dan Haggard, who presen ted them to theBritish Museum . The author foun d parts of three specimen s inp lace in the Pyritic Marls in Jun e, 19 16 . A sixth sp ecimen , thebest preserved o f all , has been in the British Museum man y y ears,an d is labelled Said to be from Lyme Regis

1 F . R . C. Re ed , The Lower Palae oz . Trilobite s o f the Girvan district

M‘

On . Palaeon t . So c . , 1903—6 , pp . 146—7 .

2 Also ibid ., p l . x ix

, fig . 2 .

3 H. Wo odward , GEOL . MAG . , 1880 , p p . 9 7 - 9 .

4 L . Do l lo , La Paleon to log ie Ethn o l ogique Bul l . Soc . be lg e de Geo l .

Mem .

, Bruxe l le s , Tome xxiii , "

1909 , pp . 406—17 . Se e also H . H. Swinn erton ,

GEOL . MAG . ,V o l . LVI, 19 19 , p p . 108—9 .

5 Pro c . Ge o l . Asso c .,vo l . xxvi ii , p t . 1, 19 17, p . 32 . A seven th examp le Was

foun d by Dr . Lan g in May ,1920 .

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L . F. Sp ath— A n ew Ammo n i te from Charm ou th. 539

The writer is in debted to Dr . Lang for p erm1ss10 n to describehis sp ecimen s, also for many valuable suggestion s . The writer alsohop es to publish in the n ear future a comp lete accoun t o f thePo lymorphidae o f the ibex - zon e at Charmouth , esp ecially o f thesuccessive developmen ts Of Acan tkop leuroceras an n oun ced byDr . Lan g in his pap er. These will o ffer a better opp ortun ity f orcorrelatin g the beds which y ielded the n ew forms described in thep resen t pap er . Five of the six sp ecimen s men tion ed above are

con sidered to belon g to on e sp ecies, but their description is givenseparately , sin ce , owin g to differen ces in the mode of preservation ,

crushin g , or ro llin g , each sp ecimen ,shows in terestin g peculiarities

which supp lemen t the eviden ce o f the ho lo typ e .The sp ecimen selected as type is the o n e that had been exhibited

for y ears i n the British Museum (Natural History ) as an examp le o fan Ammon ite rep laced by Iron Pyrites (sp ecimen No . Z 2IG) .It bears the label Apparen tly n ew . Bought at Lyme Regis, an dstated to have been foun d there . F . H. Butler The dimen sion sare

“

Diame ter

He ight o f the last wh0 1 1Thickn e ss o f the last who rlUmbi licus

At a diameter of 60 mm . these p ercen tages are resp ectively31 , 21 , 44 . The sp ecimen has the (limon itized) shell attachedexcep t on the more promin en t parts , such as the crests o f the ribsand the p eripheral tubercles . This abrasion is probably due toa certain amoun t o f ro llin g , which would accoun t n o t on ly for ' theroundin g of the p eriphery but also for the apparen t dup lication Of

some Of the costae . Apart from this , however, there appears to bea flat septum in each co sta

,which itself was probably ho llow an d

very sharp ,if on e may judge by the o ther sp ecimen s . The ribs

may therefore app ear flat an d broad,after the sty le of an nulate

Dacty lio cerati , even where there was abrasion o f on ly the crest an dtubercle

,an d where the in n er shell o r sep tum still adheres to the rib

(Fig . The n umber o f co stae is 1 14 to the whorl at a diameter o f83mm . an d about 1 16 at a diameter of 55 111m . Each begin s witha strikin g backward ben d at the umbilical slop e (Fig . an ddescribesa sigmo idal curve on the lateral area

,

'

en din g'

n ear the ven tralmargin with an elon gated tubercle or thick en din g .

“

In Fig . 3this isin dicated from the evidence o f the o ther sp ecimen s ; but in theho lo typ e the p eriphery is more o r less worn throughout .The whorl - section is roun ded

,with its greatest thickn ess about

midway between the periphery an d the umbilical suture but,owin g

to the wearin g down Of the orn amen t, the sides app ear to be flatten ed0 11 the last who rl and,

esp ecia lly n ear the end, the shell is po orlypreserved . From eviden ce

,however, of the in n er whorl , it app ears

that the sides were regularly con vex,and this regular roundin g is

540 L . F. A-

(

ZJI

Cl lh- r—A n ew Ammo n i te fr om (Ili a 7

771 0 1 1171 .

also shown in sp ecimen C 18836 . Fig . It Is a restored outhn e

section .

The umbilical edge 1s somewhat abrup t an d the slop e is flatten edwhere the costae describe the p eculiar ben d shown in Fig . 4 . Theinvo lutio n is very slight which character, together with the p eculiarco statio n , gives these forms a lytoceratid aspect . A sp ecimenfrom theCrumbly Bed,

shown to the writer by Dr . Lan g , 1s i n facta (p o orly preserved) Fi 7n bri lgtoce7asOwin g to the difficulty of removin g the (limon itic) remain s o f the

shell from the in terstices between the ribs,the suture lin e could n o t

be exp osed satisfactorily . Fig . l o is comp osite , made up from

p ortion s o f several suture—lin es at a diameter Of 65 mm .

,i . e . about

a third of a whorl from the en d o f the shell . Sin ce there are‘

traces

of. the suture - lin e still at the e n d,the sp ecimen comp lete with its

body chamber must have been over 120 111m . In diameter .

Sp ecimen 3770 (Ce ll .W. D . Lan g ) , from the PyriticMarls, 16 in ches.belowthe Belemn ite Ston e at Westhay Water

,1 1 miles east o f the

mouth Of the River Char,is n early comp lete , though crushed, and at

a diameter'

o f 90 mm . ,has '

He ight o f the last whorl

Umbi licus '44°

/o .

The thickn ess o f the shell is 22 p er cen t in l the o n e p lace where thereis n o compression ,

so that there can he n o doubt that the sp ecimen is

sp ecifically iden tical with the typ e . The co station is just a triflclo ser

,however

,sin ce there are about 125 ribs 0 11 the last who rl .

Itmay be added that, though the in n ermo st whorls are n o t preservedthe p eculiar costation Of the sp ecies is already shown at a diametero f 15 mm .

Sin ce traces of what probably was the last sutu'

re lin e are shownat a diameter o f 80 mm .

,the comp lete shell must have been con

siderably larger than the p 1 ese 1ved p o rtio n , At this spot also (justbefore the commen cemen t o f the crushed body - chamber) parts o f

the shell are preserved on the p eriphery . The median row o f

tubercles was much more distin ct o n '

the shell than on the pyriticcast

,an d the roun ded p romin en ces comp o sin g it altern ate in p o sitio n

with the thicken ed and forwardly—ben t termin ation s o f the lateralribs A very in distin ct ridge in the shap e of a seems to con n ectthe three lin es of tubercles across the .p eriphery .

‘

Sp ecimen 3769 (Ce ll . W . D Lan g) , from 12 in ches below theBelemn ite Sto n e

,Cliff Base, . south west o f Go lden Cap ,

con sists o f

half a whorl o f an Ammo n ite about 47mm . in diameter . The

sp ecimen is partly crushed, but typ ical an d extremely fin ely co state .It cleai ly shows the promin en t median lin e of tubercles o n thep eriphery , but the two lateral rows Of tubercles are irregularlycrushed again st it in p laces . The sp ecimen is n ot pyritized, as theo thers are

,but p reserved In the p eculiar pyritic marly matrix o f its

bed, an d like o ther fragmen tary fossils from this horizon suggestsdisturbed deposition

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542 L. F. Sp ath— A n ew Ammon ete fr om Charmouth.

should be men tion ed, however, that here the p eriphery has also beenwo rn down , probably to the exten t o f several millimetres . It is to beregretted that the state of preservation o f this ammon ite. do es n otp ermit o fmore exact comparison with the o ther sp ecimen s describedthis pap er o r with the genus Po lymorphites . The suture - lin e seems

to be con siderably simp ler than that o f Dag/ icems p o lymorphoides,though it could n o t be exp o sed clearly en ough fo r delin eation . On

the o ther han d the sp ecimen shows the very p eculiar costation o f

D . p o lymorphoides in p laces (if less close) , also,apparen tly ,

thetyp ical p eripheral orn amen t . In the circumstan ces it seems advisableto con sider it a distin ct fo rm from D . p o lymorphoides , an d the n ameDaytoem s 1617791

1 is here p rop o sed .

Sin ce the developmen t could n o t be studied in an y of the sp ecimen s,it may be p remature to sp eculate o n the probable evo lution of then ew series an d its co n n exion with the genus Po lymorphites an d theo ther Po lymo rphidae . But in justification of the n ew gen eric n amep rop o sed here the fo llowin g observation s may be o ffered . Theadult suture - li n e o f Da g/10697618 p o lymorphoz

'

des is of the comp lex typ eo f certain fin ely - ribbed (an d p robably p o st—jameson i ) Up tomfia ,

‘ theexact relation ship o f which both to typ ical Up tom

'

a an d to Po lymorp hite

-

s has y et to be worked out .

2 The typ ical group of thegenus Up tom

’

a has its maximum developmen t in the upp er p o rtio no f the jameson i - zon e , an d the forms have a ten den cy towardscon tin uin g the co station acro ss the p eriphery . Without go in g , forthe presen t , in to the comp lex in terrelation s of the family Po lymorphidae ,

3 it may be men tion ed that some forms, in definitelyreferred to - U. bran /

77.1 (which,however

,is keeled and has a com

parative ly Simp le suture—lin e), may show the lateral tubercles movedcon siderably n earer to the sipho n al lin e, also an in distin ct n o tchin gdue to the median lin e of slightly raised ap exes o f the V’

s al on g thep eriphery . So far as the writer is aware , however, n o thin g like thefin e an d close co station o f the n ew forms described here has beenobserved in these Up tom

’

a . The gen us Po lymorpkites, on the o therhan d

,is characterized by a very simp le suture—lin e . In the typ ical

forms o f this gen us (the small - sized,very variable Po lyan orphus

group ,an d n ot the forms o f

“

Gemme llaroccms,often in cluded here)

tuberculation o f the p eriphery also o ccurs o ccasion ally ,

‘

n o tably inP . capmm

’

us Quen stedt‘ sp .

,though here the co stae are bituberculate .

In the lin eate sp ecies o f the gen us Po lymorp kitcs however (withmerely an gular p eriphery ) , there is a certain resemblan ce to then ew forms . But on p resen t eviden ce it seems in advisable to in cludethe n ew series which , at

.

Charmouth , occurs in p ost - themtimes (yet1 Dedicated to Dr . W . D . Lan g in recogn ition o f his p ro l o n g ed an d p ai n s

takin g in ve stigat ion s o'

f the Liassic succe ssion at Charmouth .

2 The“

write r con siders that A . vern osce Zittel , p robably a Toarcian form ,

do e s n ot be lon g to Up ton ia .

3 Con fin ed ,in the write r

’

s op in ion , to the jaméson i an d ibex zon e s, an d n ot

in cludin g e .g .jche Domerian .Boule ic-eras an d late r Hi ldocerah’

ds .

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544 F. Hardy — . li i n era l Comp osufio n of Fen lan ol Si lt.

that the behaviour o f the min eral In those so il pro cesses in vo lvingthe chemical actio n o f a base,might be somewhat differen t from that

o f,say ,

calcium carbo n ateHitherto chemical an alyses o f so ils have in cluded a determi n ation

o f the to tal carbon ate con ten t (expressed as CaCO irresp ectiveo f the mode o f o ccurren ce o f carbon ate The usual method emp loy edfo r carbon ate estimation in so il an alysis i s that described by Amo s .

1

In this method the so il carbo n ates are decomp osed by actin g o n a

kn own mass o f the so il with fairly con cen trated hydro chloric acid,

which Is slowly heated to bo ilin g p o in t . The carbon dioxide evo lvedis abso rbed in caustic soda so lution con tain ed in a Reiset tower

,

and i ts amoun t estimated by“

double titration with standard acid,

usin g first phen o lphthalein an d then methy l o ran ge as in dicator .

The value o f the method lies in the fact that it gives accurateresults with so ils which are susp ected of bein g on the bo rder- lin e o fdeficien cy o f calcium carbon ate

,. an d hen ce it furn ishes the soil

chemist with data up on which to in struct farmers as to theadvisability o r o therwise of limin g arable land .

The p ro lon ged bo ilin g with hydrochlo ric acid in vo lved in theestimation is sufficien t to decomp ose an y carbon ate which i s likelyto be presen t in so ils . It do es no t differen tiate , however, betweeneasily de comp o sed carbo n ates

,such as the various fo rms o f calcium

ca rbon ate (calcite , aragon ite , e tc . ) and the more stable carbon ates,such as magn esite , do lomite, an d min erals allied to the latter

,

s iderite FeC0 3, ankerite,CaCO (Mg , mesitite . 2MgCO3

FeCOs,breun n erite , (Mg etc .

The in quiry n aturally led to two distin ct lin es of in vestigation ,

o n e o f a geo logical and min eralogical n ature . an d the o ther of

hemical and agricultural bearin g .

In the presen t pap er it is in ten ded to deal with the geo logicalasp ect of the subj ect . The results o f the purely chemical side o f thewo rk with its atten dan t agricultural application s, are set out in

an o ther p lace 2In o rder to accoun t for certain p eculiarities o f the Fen land silt

so ils,it would perhap s be advisable first to summarize what is kn own

o f the o rigin an d method o f formatio n of the Fen lan d silts Thegeo logy o f the silt lan ds i s described by S. B J Skertchl ey 3 in a

Memo ir o f the Geo logical Survey ,from which the fo llowin g accoun t

II . GEOLOGICAL HISTORY OF THE FENLAND .

The geo logical histo ry of the Fen lan d commen ces with the

breachin g of the on e - time co n tin uous escarpmen t of Chalk, which1 A . Amos , Jo urn . Agric. Sci . , vo l 1, 1905 , p . 322 .

2 F . Hardy , A Pre l imin ary In ve stigation in to the‘

Occurren ce o f diffe ren tkin ds o f Carbon ate s in So ils,to be published in Jo urn . Agr ic. Sci . , vo l . x i

,

p art i ,S . B . J . Skertchley , TheGe o logy o ftheFen lan d

F. Hardy— Mi n era l Comp osi ti on of Fen lan d Si lt. 545

j o in ed the Upp er Cretaceous highlan ds of East Yorkshire wi th tho seo f Norfo lk . The agen ts which effected this op eration were the riverso f the early Fen land,

combin ed with the usual agen ts of subaerialweatherin g . The breach was probably comp leted in pre - Pleisto cen etimes

,but prior to the o n comin g of the Glacial period the coverin g

o f Cretaceous strata was comp letely removed from the area,so that

the un derly in g Jurassic clay s were exp o sed . Durin g the Ice Agea thick coverin g of glacial dep o sits was spread over the who le o rgreater part o f the area . Subsequen t depression o f the land - surfaceal lowed the sea - to extend in lan d

,so that a great bay resulted . It

was in this bay that the true Fen - beds were dep o sited . The in flowin grivers caused an accumulation of alluvium n ear the shores of thebay . and the sea - curren ts brought down material. from the coastso f East Yo rkshire an d North Lin co ln shire . Gradually the baybecame filled w i th sedimen ts, an d in the south an d south - easternreg io ns swamp—p lan ts began to grow The remain s of thesesubsequen tly gave rise to the p eat lan ds o f the Fen s .

The silts o f the n orth western parts o f the Fen land are chiefly of

marin e o rigin . They are still bein g depo sited alon g the coast o f theWa

,sh where they give rise to salt marsh . As the tidal water ischecked in its flow. the silt falls -to the bottom,

an d thus a ban k isgradually formed agai n st the shore . As so on as this ban k rises toa certain height (estimated at 8 6 feet above ordn an ce datum ) ,Salicorn ia begin s to grow on it . The stems of this p lan t assist inthe further developmen t of the marsh by checkin g the flow of thewater and thus allowi n g a lon ger time for the silt to settle

,an d also

by ho ldin g up ,much of the fin e material when the tide beg in s to ebb .

As the marsh in creases in height , other p lan ts establish themselves,an d green marsh results . Green marsh is o n ly “

covered by sea

water at the higher tides . It marks the stage when emban kin gb ecomes practicable .The material of which the Fen silt is compo sed has been derived,

as already men tion ed, from the so ft strata (main ly glacial ) o f theYo rkshire an d North Lin co ln shire coasts, which are rap idly bein ge roded by the sea . The glacial dep osits themselves are of the Purp lean d Hessle boulder - clay typ e . They have been derived from thero cks over which the an cien t North Sea glacier passed in its movemen t from the Scan din avian highlan ds to the coast o f En glan d,an d they therefore p erhap s in clude material taken from the bedo f the North Sea .

III . MINERALOGICAL EXAMINATION OF A TYPICALSAMPLE OF MODERN FENLAND SILT .

The samp le examin ed and described below was taken from theforeshore o f the n orth - west coast of the Wash immedi ately to theseaward o f the village o f Friskn ey . It yi elded the fo llowin g resultswhen an alysed

VOL . LVII .—No . x i i .

546 F. Hardy— Mi n era l Comp osi ti o n of Fen lan d Si l t.

(A ) Mechan ical An a lys i s .

Co arse san d (17

00 to 0 20 mm . )Fin e san d (0 220 to 0 04 mm . )Co arse silt to 00 1 mm . )Fin e silt (00 1 to 00 02 mm . )Clay (be low 00 02 mm . )Lo ss on ign ition

Mo isture

92 729

(B ) Chemical An a lysis .

In so luble re sidue

Total carbon ate (as CaC0 3)Total phosphoric oxide (P20 5 )To tal p otash (K gO)To tal ni trogen

1 . EXAMINATION OF THE AIR - DRIED SILT WITHOUT PRELIMINARY

TREATMENT .

A slide o f the silt was prepared an d examin ed under 'the p etrographical micro scop e . The majority o f the grain s were foun d to besuban gular quartz fragmen ts . Their shape in dicates that the grain shad n o t been subj ected to excessive ro ll in g they resemble typ icalboulder- clay quartz particles .

A few grain s o f felspar were also n o ted . Certain of these showedtwin lamellae an d are probably of soda felspar .

The rest o f themin erals (o f den sity greater than 2 70) are described:in the n ext section under the title of heavy min erals Theycon stitute approx imately 12 p er cen t of the bulk of the silt .2 . EXAMINATION OF THE SILT WITH A VIEW To IDENTIFYING THE

HEAVY MINERALS .

In order to obtain grain s o f conven ien t size for p etrographicalexamin ation ,

a quan tity o f the silt was subjected to a 75 seco n dssedimen tation pro cess in pure water from the 7 ‘

5 cm . mark o f a

beaker in the man n er of a mechan ical so il - an alysis .

The san d fraction thus obtain ed was co llected and dried . The

heavy min erals were then separated by the use o f a mi xture ofbromoform an d ben zin e of den sity 2 70 .

A n examin atio n o f slides prepared from this heavy min eral portio f the san d fraction o f the silt y ielded the fo llowin g resultsThe chief min erals iden tified were blue—green horn blen de

(arfvedson ite) , magn etite , glauco n ite an d chlo rite , aragon ite (in thefo rm o f shel l fragmen ts an d broken o o litic grain s), do lomite ,ferriferous chert

,augite , an d tourmalin e . In this list the min erals

are arran ged in their approximate o rder of abun dan ce .Besides the above there o ccur also in lesser amoun t rutil e ,

muscovite,bio tite, stauro lite, ep ido te , zircon ,

kyan ite, apatite , an dgarn et .(1 ) Arfvedson ite is perhaps the common est heavy min eral presen t

in the silt . It has undoubtedly been derived from the ign eous

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548 F. Hardy—e Mi n era l Comp osi ti o n of Fen lan d Si lt.

When it occurs it resembles the grain s of that min eral in the LowerGreen san d . (15 ) Kyan ite is p resen t as large blade like fragmen ts ,several o f which exhibit the characteristic re - en tran t an gles, givi n ga waist like app earan ce to the grain s . (16) Apatite o ccurs in smal lamoun t as tin y roun ded

,co lourless

,highly refractive grain s . (A

further n o te on its sign ifican ce in the silt is given below . ) (17) Garn etis fairly abun dan t as co lourless, more o r l ess an gular chip s of highrefractive in dex. Such grain s o f garn et are characteristic o f man y

g eo logically recen t san ds o f East An glia,

1an d also of certain of the

Lower Green san d strata .

3. NOTE ON THE COMPOSITION I OF THE FINER FRACTIONS o r THE

SILT .

An attemp t was made to iden tify themin erals p resen t in the siltan d clay fraction of the samp le , but it was o n ly foun d p o ssibl e toreco gn ize defin itely the presen ce of quartz as the main con stituen to f the material ; of muscovi te in abundan t small flakes ; o f tin yan gular fragmen ts o f zirco n , _

an d of much calcareous matter .

IV. THE'

ORIGIN 7 AND GEOLOGICAL RELATIONSHIPSOF THE MODERN FENLAND SILT .

Assumin g that the samp le of Fen lan d silt described above isfairly typ ical of the un ifo rm dep o sit which is l wly bein gaccumulated alon g the n orth - west bo rder o f the Wash

,certai n

con clusion s as to the relation ship o f the silt may be drawn from itsmin eralogical comp o sitio n .

The gen eral assemblage o fmin erals is Very simi lar to that o f certaino f the geo logically recen t dep o sits o f Cambridgeshire , as describedby Rastal l . It is almo st iden tical wi th that o f the fin er p arts o f thep lateau—grave ls, which are mo st probably the residue of the bouldere lay o f the No rth Sea glacier . Hence it may be assumed that suchboulder - clay has furn ished the bulk of the material of the modernFen lan d silt .The p resen ce in the silt o f calcareous o o litic grain s, which havebeen gen erally somewhat altered by secon dary p ro cesses, may bedue to the admixture o f detritus from weathered Jurassicr o cks overwhich the Fen lan d rivers flew in their courses to the Wash . Theseco n clusion s are in full accord with the geo logical eviden ce which hasalready been summarized in Section II . ‘7

V. THE BEARING OF THE MINERALOGICAL COMPOSITIONOF THE MODERN FENLAND SILT ON CERTAINCHEMICAL CHARACTERISTICS OF THE SILT .

(A) CARBONATE .

The establishmen t o f the presen ce o f two distin ct kin ds o f

carbo n ates In the silt samp le examin ed i s p erhap s the chief p o in to f chemical i n terest in the in vestigatio n . The writer has elaborated

1 R . H . Rastal l , The Min eral Comp ositio n of some Cambridg e shire San dsan d Grave ls P -roc. Camb . Phil . So c . , V o l . xvii , 19 12 , p . 136 , etc .

F. Hardy— Mi n era l Comp os i ti on of Fen lan d Si lt.

7 549

an an aly tical method for estimatin g the p ercen tage amoun ts of themore easily decomp o sed calcito id carbon ate, an d of thecarbon ate of greater stability do lomito id carbon ate in marin esilt so ils . App ly in g the method to the samp le described above

,

it was found that of the to tal 8 98 p er cen t of carbon ates in the silt,5 75 p er cen t was easily decomp o sed by

'

acids (i . e . so luble in N/3acetic acid) , whereas p er cen t (by differen ce) required a stron geracid for its decomp o sitio n ,

an d is assumed therefore to be o f then ature o f do lomi te o r allied mi n eral carbon ate .

7 The details o f the an aly tical method used in the estimation of

calcito id an d do lomi to id carbon ate in silt so ils,an d an accoun t of the

agricultural sign ifican ce o f the p resen ce o f these two kinds of

carbon ates in such so ils,are given in the writer’s forthcomin g pap er

already quo ted .

(B) POTASH .

The chiefp o tassium - con tain ingmin eral in the silt is muscovite,and it is n o tewo rthy that the greater amoun t o f this min eral appears(from the p etro graphical examin ation ) to o ccur in the fin er fractiono f the material . Although orthoclase felspar was iden tified as a constituen t of the silt, it was n o ted that its amoun t was comparativelysmall . The o n ly . o ther p ossible p otassium - con tain in g min eralsiden tified were tourmalin e an d glaucon ite . The former min eral ,however, is so very stable that it is of n o importan ce as a sourceo f p o tash in so ils con tain in g it, an d glaucon ite , whi ch when freshmay con tain as much as 8 p er cen t of K20 ,

1 is here presen t chi eflyin a much decomp o sed state an d also in such comparatively smallamoun t that it may be left out o f con sideration as an imp ortan tsource o f p o tash in the silt .Thus the chief source o f p o tash for the use of crop s grown on

Fen lan d silt similar to that described i smuscovite .Accordin g to the chemi cal an alysis, the to tal p ercen tage of K2

O

in the silt exami n ed in 12 24 . This corresp on ds to about 10 p er cen tof muscovite (assumin g the absen ce of o ther po tash - min erals) . Itis relatively high as compared with the K20 con ten t of typical so ils ,which usually li es between 0 1 an d 10 p er cen t . Nevertheless the

successful growth o f crop s (esp ecially p o tato es) in the cultivatedregion s of the reclaimed silt Fen lan ds. frequen tly n ecessitates theli beral use o f p o tassic fertilizers . This fact suggests that the po tashsupp ly o f the Fen lan d silt so ils is o n ly relatively slowly available , sothat it may fail to satisfy the full n eeds o f certain crops which requi rean abundan ce of this p lan t fo od . It may be exp lain ed by theresistan ce to weatherin g whi ch is a kn own characteristic ofmuscovite .

(C) PHOSPHATE .

The o n ly pho sphatic min eral foun d in the si‘t 'was apatite .Chemi cal an aly sis showed that the total pho sphate (P20 5) p i esen t

1 Clarke, Data o f Ge o chemistry : .

Bu l letin 616 , U .S. Ge o l . Surv . , 19 16,

p . 5 16 .

550'

1

F. Hardy— Mi n era l Comp osi ti on of Fen lan d Si lt.

in the silt samp le is 0 112 p er cen t, which co rresp o n ds to about0

7

28 p er cen t of apatite . Frequen tly in so ils (esp e cially i n p eat an do ther so ils rich in humus) , pho spho rus probably also o ccurs as

organ ic pho spho rus comp oun ds . In the . case o f the silt un dercon sideration ,

the p o ssibility o f the presen ce o f o rgan ic pho sphorusis n egligible, sin ce the silt con tain s on ly 0 034 p er cen t of n itro gen(corresp o n ding to about "0 48 p er cen t of humus) . Hen ce we maysafely assume that the o n ly pho sphorus c omp oun d presen t in thesilt is the .min eral apatite . The p ercen tage o f pho sphate (0 1 12 p ercen t P2Og) is o f average amoun t for a so il ; the ran ge for typ icalso ils bein g between 00 6 an d 02 0 p er cen t P20 5 .

(D) OTHER MINERAL PLANT - FOODS .

The silt samp le con tain ed an abun dan ce o f magn esium - con tain in gmi n erals

,an d also o f min erals co n tain in g iron ,

sodium,an d calcium

,

so that there is n o dan ger o f a deficien cy o f these essen tial elemen tso f p lan t _ growth should the lan d subsequen tly be brought in tocultivatio n .

The above results furn ish an examp le o f the imp o rtan ce'

of a

min eralogical examin ation o f a so il - typ e with a View to in terpretin gthe figures o btain ed by a chemical an alysis

'

carried out alo n gven tio n al lin es . In the op in ion o f the writer to o little atten tio n isp aid to the p o ssible aid which min eralo gy may affo rd the so il - chemi stin his efforts to appreciate the sp ecial agricultural treatmen tfrequen tly n e ededb y certain “so il - typ es un der an in ten sive systemo f cultivation .

In con clusion ,the writer wishes to express his in debtedn ess to

R . H. Rastall , fo r his invaluable assistan ce an d sympathydurin g the p ro gress o f the wo rk outlin ed above . Also to E . J . Ro

_,berts

o f the Cambridge Scho o l o f Agriculture, for p ermission _

to use theresults of the an alysis o f the samp le cho sen for exami n ation .

SUMMARY .

1 . A samp le Of modern Fen lan d silt con tain in g 8 98 p e r cen t o fcarbo n ate was. foun d o n . mi n eralogical exami n ation to in cludedo lomi te as well as aragon ite in its min eral assemblage .2 . The do lomite is presen t in fresh an gular cry stal grain s which

suggest a seco n dary an d recen t origin of the mi n eral . It has p o ssiblybeen dep osited from sea- water which p eriodically covers the foresho re of the Fen land bo rder of the Wash .

3. The gen eral mi n eral composition o f the silt resembles clo selythat o f certain geo logically recen t dep o sits of Cambridgeshire , an dp o in ts to the boulder—clay l eft by the No rth Sea glacier as the chi efsource o f the material o f which the silt is comp osed . The silt hasmain ly been dep o sited by sea - curren ts whi ch carry southwards th‘eeroded glacial dep o sits of the South Yorkshire and North Lin co lnshire c o asts .

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552 W. B. Wr ight— A Theory of the Marg i n a l Dr ift.

to severer climatic condition s gives us some in sight in to the effects.

o f reduction o f temp erature on the activities o f the ice - sheet .In virtue o f its di scharge in to the waters of the late - glacial seathe outwash from the ice - margi n ,

durin g its retreat across Fin land,

has produced in that coun try'

a series o f clays with well markedseason al lamin ae, which give an effective measure o f the rate o f

ablatio n .

_

Durin g the several halt - ,stages themost marked of which

are tho se corresp ondin g to the in n er an d outer wreaths o f the .Salpausse lka Mo rain e

,ablatio n as recorded by these lamin ae was

reduced to a min imum . It is a fairly safe deduction that these haltsin the retreat were the result o f a lowerin g o f temperature , probablyo f mean an nual temp erature , but mo st certain ly o f summertemp erature , sin ce the coarse summer zon e is almost wan tin g in thelami n ae . Further, o n mapp in g out the successive p ortion s of the

ice - margin an d plo ttin g the rate of retreat again st the correspon di n gy ear, Dr . Sauramo discovered that

, in almo st every case,a halt was

fo llowed by an acceleration in the rate o f retreat,lastin g for a

period o f some fifteen y ears o r so ,after which

.

there was a gradualreversion to the n ormal rate . From this result, combin edwi th thefact that the lamin ated clays correspondin g to these y ears of rap idretreat show n o eviden ce o f abn ormally great ablation ,

he draws thecon clusio n that durin g the precedin g halt - stage the margin of the icesheet had become thin n er, and con sequen tly wasted away morerap idly when the n o rmal ablation was resto red .

Now,wastin g without an y equivalen t ablation is

“

capable of o n ein terpretation on ly . It clear must be due to evapo ration from the

surface of the ice—sheet, that is, passage from the so lid to the gaseousstate either directly o r wi th so l ittle developmen t of water that thelattermerely mo isten s the surface sn ow an d forms a zon e '

o f slush, butn ever gathers in to run n els an d streams . The zon e of slush

,accordi n g

to the observation s o f Nan sen , is n ot, even in the case o f Green lan dice

,which is un dergo in g ablation

, o f an y great width . The co n

clusion,therefore, to be drawn from Dr . Sauramo

’

s observation isthat direct evap o ration '

from the ice may ,un der sufficien tly low

temp erature con dition s, become an imp ortan t factor in glacialcon tro l .The Glacial An ticyclon e .

— It is n ow widely recogn ized that an icesheet

,o n ce it attain s sufficien t magn itude , establishes its own

p erman ent meteoro logical con di tion s an d win d system ,the so - called

glacial an ticyclon e It is n ourished, n o t by sn owfall as we kn owit

,but by frost - sn ow o r ice - crystals precip itated from the descen di n g

air of the an ticy clon e when it comes in to proximi ty with an d is

chilled by the surface of the ice . The cen tral portio n s of the an ticy clon e drawup on higher, co lder, an d drier regi on s of the atmo spherethan the p eripheral . The p eripheral p o rtio n s o f the ice - sheet aretherefore better n ourished than the cen tral , more esp ecially if theyadjo in l

an ocean . This is probably the exp lan ation o f the westwardshifting o f the cen tres o f glaciation in the British Isles emphasized

esp on din g eastward shiftin g in NorthMr . Lamp lugh expressed the idea by say in g 1 As the

o f ice ro se higher in the path of the mo isture - laden air

they must have gain ed in creased effectiven ess as co n den sers,n o t o n ly augmen tin g the sn owfall in one quarter

,but also

in g the precipitatio n in the regio n to leeward .

” It mightco n formi ty with modern ideas o f the meteoro logy of

say that they drew down up on their surface the bulkair o f the upp er curren t which was passin g acro ss the

towards the in terior in vi rtue o f the an ticyclon e

t is clear from,what has been said above

s cen tral area becomes -

starved,active

the p eripheral areas . Even in thesethere is u l ess n ourishmen t

,as eachextrafactorto be

imp ortan t factor is the in creased‘ This is

,o f course

,obvi ous if. the

thrustin g forward in to the zon e o f ablation ,but even if

n ever reached there must ultimately come a limit . Withe m size an d p ower there 18 drawn down the cen tral pipe of;icyclo n e a con tinually greater prop ortion of dry air from the'

egion s o f the atmosphere, an d this spreadin g radially over theof the ice causes ever- in creasin g evap oration . Towards

riphery it n o doubt partly mixes wi th , but also ten ds o n

t of its great weight to wedge in below,the mo isture - bearin g

cen din g in the zon e of n ourishmen t . The evap oration effectstrated by. Sauramo to be a workin g factor in the co lder stagesFin n ish retreat may thus become a really p owerful agen t ofdurin g the rigour o f the glacial maximum .

15 of Accumulated Gradien ta n d the Radial Sn ow- drift.— .Thus,tilin g n ourishmen t an d in creasin g wastage by evapo ration ,

sheet may reach a limi t o f growth without ever exten din g in to1c o f ablatio n . It 1s n ow losin g by evap oration as much as it) y precip itation . Its p owers of expan sio n ,

however, do n ot.

re, _ for it has accumulated a gradien t , an d must con sequen tlyits fron tiers un til the gradien t becomes so low as to be

Ltive . In do in g so it still further decreases its n ourishmen treases its evap oration ,

so that the latter becomes domin an t .lready wastin g from above downwards where it reaches itsum exten t

,an d this wastin g con tinues un til the fron t is again

awn to the lin e o f balan ce , where precip itation an d evap oration1al . Here it awaits an amelio ration of climate before ablation3 in an d further withdrawal take p lace .'

re s . Addre ss to Section 0 , British Association , York , 1906 , p . 14 .

5 54 W. B. Wr ight-A Theorg of the Marg i n a l Dr ift.

The belt thus gen tly in vaded with pro gressively weaker mo tionan d as gen tly exp o sed without ablatio n by the slow downwardwastin g o f the dead ice is the o lder an d featureless margin al drift .The lin e o f balan ce to which the ice retreated in the case of theEurop ean Ice - sheet is somewhere in the n eighbourho od of theYo un g En d - morain e p erhap s a little to the south o f it . The exactlin e was p robably the n orthern limit o f the lo ess, which, excep t ina few p laces, do es n ot seem to reach right up to the mo rain e . Itseems n atural to supp ose that the lo ess which covers the margin aldrift was a product o f the dry climate of the maximum o f co ld

,an d

ceased as so on as there o ccurred a rise in temp erature o f sufficien tmagni tude to in troduce the factors o f ablatio n an d more copiousprecip itation .

The prin ciple o f accumulated or residual gradien t in voked .to

exp lain the advan ce bey on d the lin e o f balan ce requi res furthercommen t, because it is n o t clear that the ice - mo tion would n ot in

the main have di scharged the. gradien t con curren tly wi th thee stablishmen t o f the balan ce . Two con sideration s bearin g upon thispo in t are worthy o f n o te . In the first p lace ice mo tion mustclearly be greatly slowed down as a result o f extreme co ld, for itdep en ds en tirely o n the phen omen on of regelation ,

which becomesin creasin gly difficult with lowerin g o f temp erature . Though thee xact referen ces have escap ed hismemory ,

the writer believes thatShackleton and Sco tt have bo th commen ted o n this checkin g of

g lacial movemen t by co ld as bein g a fact wi thin their experien ce .This con ceptio n ,

however,when clo sely examin ed, though it makes

the p robability o f a residual gradi en t greater, do es n ot settle thequestion . There is, however, an other mean s of expan sion ,

whichprobably becomes of great relative importan ce un der co n dition s o f

e xtreme co ld . This is the sn ow—drift on the surface o f the ice - sheetcaused by the radial wi nds . Peary con siders that in the n orth o f

Green lan d this is the con tro llin g factor in distributio n . Providedthe we margin do es n ot exten d in to the zo n e of ablation ,

it is clearthat it may be con siderably advan ced by this method even after thee stablishmen t o f the balan ce . What 1s n o t clear i s that this modeo f expan sion actin g alon e would result in sufficien t ice—motion at

the so le o f the sheet to produce even the feebly develop ed margin aldrifts . A combin atio n o f bo th agen cies o f advan ce would meet thefacts admi rably ,

and accoun t n o t on ly for the gradual attenuation o f

the drift .at the feather - edge , but also for such extra -

glacial ”phen omen a as the trail ” o f Southern Eng land .

Absence of“ Margin al Drift in the n eighbourhood of the Atlantic.

It is a n o teworthy fact that the belts o f margin al , featureless,'

an d

lo ess—covered drift l n Europ e an dAmerica do n ot exten d to the shores(o f the Atlan tic

,but 1n these areas the stron gly featured lo ess - free

drift stretches south to the lin e o f maximum glaciation . This resultis deducible from the idea that the margin al drift is the product of anadvan cedue to residualgradien t andwind- driftafterthe establishmen t

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REVIEWS.

AN INTRODUCTION TO PALJEONTOLOGY . By A . MORLEY DAVIES,D .Sc . pp . xi , 414 . Lo n don : Murby

'

& CO . 1920 . 12s . 6d. n et .

THE task‘ Of writi n g a small textbo ok on the; p alaeon to lo gy o f

'bo th an imals an d p lan ts, “

suitable for studen ts who have had n obio lo gical train in g, is on e o f great difficulty ; , but much may beexp ected when such a task is un dertaken by an exp erien ced teacherwho, as shown by his work o n the Geograp hy of the British Isles, isalso alucid writer .

I- n ste ad o f the more usual method o f describingfirst the zo o logicalcharacters o f each group ,

the author begins with an accoun t o f thehard parts of some typ ical fossil forms

,an d then refers to the

characteristics Of the soft parts as seen in livin g represen tatives ;but whether this, without illustration s, will give studen ts a .

satisfactory idea Of the zo o logical characters o f the group seems

doubtful;' The order in which the various groups are taken i s :

Brachiop oda, Lamellibran chia ,Gasterop oda ,

Cephal opoda Trilobitaan d o ther Arthro p oda, Vertebrata, Echin odermata ,

Grap to lites,Corals, Porifera ,

Pro to zoa, Bryo zo a (Po ly zoa) , An n elida ,Plan ts

NO reaso n is given fo r this order, an d it would have been easier forthe n on bio lo gical studen t to understan d the relation ship o f theroup s if a table Of classification had been given at the begin n in g

Of the bo ok . Similarly the use of the same kin d Of type for the n ameso f group s of differen t value— Phy la , Classes, Orders, Gen era ,

etc .

do es n o t make fo r clearn ess . Very un equal treatmen t is accorded todifferen t

'

group s thus 68 pages are devo ted to the Class Cephalop oda,

but'

the great Phy lum Arthropoda (o ther than Trilobites) is disp o sedOf i n 4 pages ; the Vertebrata receive 18 pages, an d Plan ts 13pages .

The accoun t Of the Cephalop oda seems to be more detailed than 1s

suitable for elemen tary studen ts , an d would have been easier to fo llowif it had been divided in to three .section s dealin g wi th the Nautilo idea,.the Ammon o idea

,an d the Dibran chiata resp ectively .

“While some parts of the bo ok have the sty le Of a lecture o thers,n o twithstan din g the author’s prefato'

ry remark,appro ach clo sely

to the fo rm Of a descriptive catalogue . The autho r is certain ly .

n ot sparin g in the use Of techn ical terms , an d In some p laces givesthe Impression o f try in g to in troduce as man y as p o ssible ; this willcertain ly n ot p rove an attraction to n on - bio lo gical studen ts . Thetwo chap ters o n Rules o f Nomen clature an d Division s Of

'

Geo logical Time ” ,although valuable for advan ced studen ts, seem .

out Of p lace In an elemen tary work , an d we thin k the “

space mighthave been put to better use by givin g a more adequate accoun t ofsome “Of the group s Of fo ssils which are dealt with to o briefly .

The origin al" illustratio n s are satisfactory ,but the figures

cop ied from o ther authors have n ot in all cases been well chosenfor i n stan ce , in the echin o ids the figures gen erally omit o r show

Revi ews— Pump el ly’

s Excavati on s at A n a-

at . 557

i n correctly the structure Of the ambulacra— a feature Of prImaryimportan ce , an d Often not clearly seen in sp ecimens .

We have con sidered thiswork from the p o in t Of vi ew Of the studen tOf palaeo n to logy rather than '

from that of the sp ecialist , an d havedrawn atten tion to some features in the hOp e that the author mayhave the Opp ortun ity Of in creasin g the utility o f his wo rk . Weregret that the autho r should have been co n ten tedwi th the statemen tValuable as a p relimin ary train in g in gen eral Bio lo gy is to the

s tuden t Of Palaeo n to logy an d we doubt if an y petro lo gistwould have made a simi lar remark imp ly in g that a prelimin arytrain in g in Physics , Chemistry ,

an d Min eralogy is n o t essen tial fo rthe study of Petro logy .

PUMPELLY’

s Ex cAVATIONs AT ANAU,TURKESTAN , AND THE ORIGIN

o r DOMESTICATED ANIMALS .

HE importan t archaeo lo gical r esults Of Professo r RaphaelPump e lly

’

s exp edition to the Kurgan s (co n tinuously in habitedsites, n ow like Tumuli) , of An au in 1903—4 were made public byhim In his In terdep en den t Evo lution of Case s an d Civilization s ”

published in the Bulletin o f the Geo logical So ciety o f America(xvii , 1906, 637 The details are n ow made kn own in hi s

Exploration s in Turkestan , Exp edition Of 1904,

PrehistoricCivilization s Of An au

”

(Carn egie In stitutio n ) , which con tain sDr . Duerst’s exhaust1ve rep o rt o n the vertebrate remain s . As

to the archaeo logy it will be en ough here to roughly tabulate theresults as

Eviden ce . Date . Proof .

A n au V . 4th ce n tury A .D . S-assan ian co in s .

Gap (strata de n uded an d l o st) .An au IV. 4 fe et. Iro n ag e Iron sickle s .

(c . 1000—1300 B . C . ) Whe e l - made p o ttery .

Gap o f 8 fe et o f strata app are n tly un o ccup ied .

An au III . 64 fe e t. Copp er ag e 29 cop p e r Obj e cts flint kn ives ,(c . 2000 saws an dscrap e rs , clay figure s

o f Ishtar , bird - he aded l io n

se al , whe e l - made p otteryGap (strata den uded an d lo st) .

An au II 1 5 fe e t. Early co ppe r age Fl in t sickle s 4 copp e r obj ects ,(c . 3500 sl in g ston e s , fl in t kn ive s ,han d - made p otte ry .

An au I. 45 fe et. Ston e age Dome stic an imal s ; on ly wild

(Neo l ith ic) an imal bon e s at base .

—100001The sp ecial in terest to readers o f the GEOLOGICAL MAGAZINE will

n aturally lie in Dr . Duerst’

s rep ort, an d as this is elaborate o n e maybest secure his gen eral results by paraphrasin g Pro fessor Pump elly ’

s

sketch in his Remin iscen ces (New Yo rk, There werebon es

,Of which on e - third were skulls, jaws, an d teeth .

Exceptin g human skeleton s,the. lower 5 feet con tain ed bon es on ly

o f wild an imalsf The n ext 40 feet con tain the reco rd o f the progresso f domesticatio n on this site successive ly of ox , pig , an d sheep— an d

558 Rep orts (Q' Pr oceedi n g s— Mi n era log i ca l Soci ety .

p robably horse— as shown by the in creasin g p oro sity Of the bon esun der the chan ged condition s Of life

,an d by the diminutive size o f

the an imals . First, out o f BO3 n amadicus there was developeda large bovid with lon g horn s (the same as foun d In an cien t Egypt)At the en d o f An au I there app eared a short horn ed breed

,which

may have been produced from the lo n g h- Orn ed o x o r may be a n ew

fo rm brought in by the n ewcomers o f An au II . Domesticated pigbegin s to be foun d about 12 feet from the base . The wi ld Ovis vign eiis in the lowest strata

,but 28 feet above this an imal had become

domesticated,somewhat smaller in body ,

with smaller horn s .

This'

last p ersisted till the end of An au I,but durin g the time a

smaller variety was bein g evo lved, un til there was established a breediden tical with Ovis p alustris, the turbary sheep Of n eo lithicEuro p e . The horse aboun ds in An au I , an d Duerst thin ks it wasdomesticated ; at an y rate, it was descen ded from the wild Equusp rzevalshii , an d app ears to be the an cestor Of the thin - limbedArabian sto ck . Dog do es n ot app ear till late in An au II (but its

'

n ot bein g found is n o pro o f o f absen ce) .Of human remain s two adults an d seven y oun g skulls were fo

'

un d .

These arg'

al l dOlicho cephalic, n ot mon go lo id, an d seem to po in t'

to Mediterran ean con n exion s .

That agriculture was kn own is shown by the siliceous skeleton so f the chaff Of “

a p rimitive variety of wheat an d Of two - rowed barleyan d chopped straw

,all Of which were Obtain ed from fragmen ts o f

p o ttery from the very lowest lay ers by Professor S‘

chellen berg .

The impo rtan ce of all these statemen ts can n o t be overestimated,

but we can do n o'more here than refer the reader to the rep orts

themselves for the details,an d to ProfessorMyres’s Dawn of History

for their bearin g on the early history OfMan .

REPORTS AND PROCEEDINGS.

MINERALOGICAL SOCIETY .

An n iversary Meetin g , November —Sir William P . Beale,Bart ,

K .C Presiden t, in the chair .

Dr . E . S. Simp so n : A Graphi c Method fo r the Comparison~o fMin erals with FourVariable Compon en ts formi n g Two IsomorphousPairs .

”

In the sp in el - chromite series the two pairs are MgO,FeO

an d A120 3, Orz0 3, and the gen eral fo rmula is (Mg , Fe )O (Al , Or)zO3The relative mo lecular prep on deran ces Of the compon en ts of eachp air stated as a p ercen tage Of the maximumare given by the formulaea z 100 (m +f ) an d y 100 (a c) , wherem

, f , a ,c represen t the number of mo lecules Of MgO,

FeO,A120 , ”

Orz0 3 resp ectively . The values o f x an d y , calculated from a numberOf published an alyses, and from n ew an alyses Of cey lo n ite fromCamban , Western Australia ,

are p lotted o n rectan gular co—Ordi n ates .

The four corn ers of the main square are occup ied by the pure

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5 60 Rep o r ts cf:Pr oceedi n gs— Edi n burgh Geo log i ca l Soci ety .

a parallel - Sided trough con tain in g the liquid to be de termin ed,in

which is immersed a right - an gled prism Of kn own in dex n ear thato f the liquid’

. Two images Of the signal are fo rmed, an d the an gulardistan ce between them is read on the ey e -

p iece scale this readin gi s prop o rtio n al to the differen ce Of in dex between the liquid an d thep rism . The scale divisio n has the same value, whatever the , in dex-Oi the prism used .

EDINBURGH GEOLOGICAL SOCIETY .

October 20,1920 .

— Mr ..

E:B . Bailey , M.C. ,B .A .

,

Presiden t,in the Chair .

No tes o n the Structure . Character, an d‘Relation ship Of the

Lower,Carbo n iferous Limeston es Of St . Mon an s,Fife . ” By David

Tait an d James Wright"

.

In t his commun ication the authors gave a description ,with

d iagrams,o f the lower members Of the Carbo n iferous Limeston e

Series which are expo sed o n the shore fron t in ,an d to the east , Of

St . Mon an s . Addition al fo ssil lists from certain horizon s were alsog iven . Some Of the p o in ts brought fo rward have n ot hitherto beenpublished . Eviden ce was adduced to show that the white limes to n e o i 0St . Mon an s un dergo es a remarkable chan ge from a coralliferous limesto n e at high - water mark at Coal Farm to a limesto n e o fquite n ormal character at St . Mon an s Burn . Atten tion was alsodrawn to the differen ce in the cover Of this limesto n e , and the chan geit un dergo es towards low- water mark at Coal Farm . The p seudobrecciated limeston e o f St . Mon an s probably owes much Of its

brecciated character to faultin g . Besides the Co al Farm expo sure ,this bed also appears in its prop er po sition o n the west side of thesyn clin e at . St . Mon an s Burn . In al l the po sition s examin ed, wherei t is un disturbed it may be described as a limeston e of n ormaltyp e ; where it has been subj ected to faultin g , as at Coal Farm an d at

places o n the w estern limb , it shows the p seudo - brecciatedstructure o f the high - water exp o sure of the Coal Farm section . Theo verly in g shales at such p laces are much disturbed an d slicken sided .

The higher limeston es in the sequen ce retain their characters o n

both sides o i the fo ld,but the in terven in g strata on the west are o n

the who le thicker than tho se o n the east .Description was also given of a remarkable limeston e below thewhite limeston e Of Coal Farm . At high water this bed is n ormal

an d on ly 6 in ches thick . Seawards it passes un der a coralliferouslay er, which gradually attain s a thickn ess o f 2 ft . 9 in . ,

and fromthis po in t tap ers away altogether . Fo r a di stan ce Of 4 yards therei s n o limesto n e . It begin s again as a .thin coral bed of the samen ature, thicken s out to 18 in ches

,then dies away n ear low- water

mark .

Atten tio n was drawn to the n odular and o ther characters Of thesel imeston es an d the eviden ce they afford Of .the peculiar con dition su n der which they were dep o sited .

INDEX.

BERDEENUn ive rsi ty ,the Nico l

A Memo rial at, 387.

Ag e o f Milburn Group , A . D . N . Bain ,

246 .

Aids in Practical Ge o lo gy , Profe sso r

Gren ville A . J . Co l e , 9 1 .

Alkal i Ign e ous Ro cks , Origin of,Dr. J . W . Evan s , 469 .

American Ge o log ist o f Last Cen tury ,Jame s Hall , 483.

Amish - Athapapuskow Lake District,E . L . Bruce , 282 .

Ammo n ite , n ew g e n us , Day iceras,538 .

Ammon ite Siphun cle , A . E . Trueman ,

26 ; L . F. Sp ath , 142 .

Ammon ite s, Jurassic, East Africa ,

L . F. Sp ath ,31 1 , 35 1 .

An tarctic Brachiop ods , J . Allan

Thomson , 42 .

Arbouin Copp erMin e s, Cardro ss, L . C.

Bal l, 374 .

Arran an d Sn owdon ,Pi e - Glacial

Vall ey s Of, J . W . Gregory ,

Arsen ic an d An timon y Ore s , H.

Dewey , 378 .

A rvico la me liten sis , sp . n ov . ,Dorothe aM. A . Bate

,2 10 .

Austral ia, South ,Min e s of, 184 , 520 .

Do lomite s , 449 , 492 .

Pho sp hate s , 181 .

AIN,A . D . N . ,

Age of Milburn'

Group , 246 .

Baker, Herbert A . , Quartzite Pebble so f Oldhaven Beds, 62 Mechan icalCo n stitution of Aren ace ous Sedi

m en ts , 321 , 363, 4 1 1 , 463.

Bal l , L . C.,Arbouin Co p p er Min e s ,

Cardro ss, 374 .

Barke , F . , Quartzose Con g lome rate,

Staffs, 76 .

Bastin , E . S .,

Nevada , 183.

Bate,Dorothe a ,

M.A . , New Vo le , etc . ,

from Malta , 208 .

,Bather, F . A . ,

Men de lism an d

Palaeon to logy ,470 ;P

’

alaeon to l ogica l

Abstracts , 19 1 Pre siden tial

Addre ss , Se ct . CBrit . Asso c . , 473.

Beasley ,Hen ry C. , Obituary of , 94 .

Be e rbachite Lizard,Prof . T . G .

Bon n ey , 339 .

Bil lin gs , Walte r R . , Obituary o f, 287 .

VOL . LVII .—NO . XII .

Ore s of Ton op ah ,

Blo ck “Moun tain s in New Zealan d ,

C. A . Co tton , 90 , 178 .

Bonn ey , Profe ssor T . G . ,Be erbachite ,

Lizard , 339 ; Glacial Erosion ,431 .

Bosworth , T . Mid - Con tin en ta lOilfie lds , 428 .

Boule , Marce l lin , The Grimald iCavern s, 130 .

Bourn emouth , Chin e s an d Cliffs ,

Hen ry Bury , 7 1 .

Cliffs , C. Carus -Wilson , 384 .

Bowen , N . L. , Cry stal lizationDifferen tiation ,

238 ; Differen tia

tion in Ign e ous Magmas, 86 .

Brachiop od Beds o f the Midlan dsDistribution ofProductus

‘

humerosusProfe sso r T . Fran kl in Sibly ,

'

20 .

Brachiop od , Gen usP latystrop hia ,Eula

D . McEwan 88 .

Ether idg i n a ,D. K . Greg e r, 535 .

Nomen clature , J . Al lan

Thomson ,47

The Gen oty p e of Sp irifer,S . S . Buckman , 18 .

Bragg , W . L . , Cry sta-l Structure , 472 .

Brammal l,Alfred , Mi crochemi caf

Methods , 123.

British Association , Cardiff,469 , F. A . Bather’s Addre ss, 473.

British Museum Staff, 581 .

Bro oks , Charle s E . P.

Quate rn ary Dep osits, 423.

Brown ,J . Coggin , Tun g sten

"

an d Tin

in Burma , 92 .

Bruce ,E . L . Amisk Athap apuskow

Lake District 282 .

Brydon e , R . M. ,Li n gula in the Chalk ,

429 ; Orig in of Fl in t , 401 .

Buckman , S . S . ,The Gen oty p e of

Sp irifer , 18 ; Jurassic Chron o logy ,

137 .

Bury ,He n ry , Chin e s an d Cl iffs of

Bourn emouth , 71 ; Escarpme n ts

an d Tran sverse Rivers , 120 .

Butle r, G . Mon tague ,Handbo ok o f

Min e ralogy ,181 .

Ge rard W. ,Faun a

'

of Lowe r

Chalk n ear Re igate , 269 .

British

AINOZOIC Fo ssils,Chapman ,

Ca ldon Low , Staffs, Quartzo se Cong lomerate at

,F . Barke , Whe e lton

Hin d , A . Scott, 76

Papua,F.

562 I n dew.

Caldon Low,

'

J . Wilfrid Jackson an dJ . Kay e Charle sworth , 487 .

Calman , W. T . ,Marin e Borin g

An imals , 180 .

Can tril l, T . C., Un bedded Iron O re s

,

38 .

Carbon ife rous Brachiop oda ,F. J .

North , 136 .

Fo ssils from Siam,

'

F. R .

Cowp er Re ed, 1 13, 172 .

Nautilo ids,Whe e lton Hin d , 405 .

Cardiff District, Ge o logy , Profe ssor

A . Hubert Co x , 469 .

Carrock Fe ll Gabbro , Metamorphismo f, Sidn ey Me lmore , 266 .

Carus Wilson ,C . , Bourn emouth Cli ffs ,

384 ; El in t Problems , 474 .

Chalk, Lower , Faun a ,n e ar Re igate ,

Gerard W . Butler, 269 .

Chan n e l Islan ds, John Parkin son ,4 1 :

Chapman ,E . , Cain o zo ic Fossi ls ,

Papua , 92 Palaeo zo ic Fo ssils in

Victoria , 88.

Charle sworth , J . Kay e Quartzo seCon glomerate , Staff

'

s , 487 .

Charophy te Fruit, _F

‘

ossil , Jame s

Grove s , 126 .

Chin e s ahd Cliffs_of Bourn emouth ,

He n ry Bury ,7 1 ; C. Carus Wilson ,

Co le, Gre n vil le A J . Aids in Practica l

Ge o logy , 91 .

Co rnish In stitute o f En g in e ers , 523Cornwall, Ge o logy o f Wolfram Min e ,

E . H Davison , 347 .

Co tton , C. BloCk Moun tain s, New

Cox, Profe ssor A . Hubert, Ge o l ogy o f

Cardiff District , 469 In tra

.

'Jurass ic Movemen ts in the Midlan ds , 198 ; Magn etic Disturban ce

in Midlan ds , 133.

Cre tace ous Silicisp on g iae ,M. O’Con ne l l

Cry stal Structure , Pro fe ssor W . L .

Bragg ,472 .

Cry stal lization - Differen tiation ,N . L .

Bowen 238 .

Cun n ingham Craig ,E . H. , Sgurr o f

Eigg ,

Currie , Ethe l , Echin o ide a , We st

Persia 500 .

Curtis,A H . ,

Man gan e se Ore s 279 .

ALY, R . A . , Iro n Ore s , Kirun a ,

282 ; Recen t Worldwide Sin kin g o f Ocean leve l , 246 .

DaVi‘

gs, A . Mo rl ey , Palaeon to l og y ,

55

Davie s , David , Palaeon to l ogy ofWe st

phal ian Co al me asure s , 473.

G . M. , Nomen clature of HeavyLiquids , 287 ; Tin ore s, 179 .

Davis , W . M. , Glacial Ero sion of

Sn owdo n , 38 1 Phy siographicRe lation s o f Laterite

,429 .

Davison , E . H . , Wo lfram Min e, We st

Co rnwal l , 347 .

Day iceras, g e n . n o v. Ammon ite , 538 .

De n dy , Profe ssor A . , Men de l ism an d

Palaeon to logy ,47 1 .

Devo n ian , Torquay , Faun a o f, F. R .

Co xvp er Re ed ,299

,

Dewey , H. , Arsen ic an d An timon yOre s , 378 ;

'Un bedded Iron Ore s ,

Diamon d - bearin g Pip e s in Brazil,

Robe rt R . Wal ls, 447 .

Diatomace ous Earth o f Lomp o c ,

Cal ifo rn ia , Sir Nicho las Yermo lo if

(Pre fatory Note by Dr . A . SmithWo odward) , 27 1 .

Dixey , F Lateritization in Sierra

Le on e , 2 1 1 ; Phy siography o f

Laterite , 524.

Do e lte r’

s Min eral Chemistry ,278 .

Drift, Marg in al , 55 1 .

Duerdcn , Profe ssor J E . , Men de lisman d Palaeon to l ogy ,

470 .

ARTHQUAKE , Porto Rico H F.

Re id an d S . Tabe r, 377 .

Earthquake s , Oregon , Warren Dup re

Smith , 336 .

Echin o id o r Crin o id ? Johan n e sWan n e r, 371 .

Echin o idea from We stern Pe rsiaJ . W . Gregory an d Ethe l C urrie ,

500 .

Ho le ctypo ida, Morpho logicalStudie s , H. L . Hawkin s , 393.

Econ omic Ge o logy , Will iam H .

Emmon s, 227 .

Cen tral Scotlan d Geo l .

Surv . Memo ir, 427 .

Haze lton , B .C. , J . J .

O’

Ne il l, 90 .

Editorial Note s , 1—3, 49—51,97—9 ,

145—7, 193—4 , 241—2 ,

- 289 , 337—8,385—6 , 433, 481—2 , 529—31 .

Elutriatio n in In ve stigatin g Lo o se

Aren ace ous Sedimen ts,H . A . Baker,4 1 1

,463.

Emmon s, Wil liam H . ,Econ omic

Ge o lo gy , 227 .

Eo cen e Strata An g lo- Fren ch Be lg ian

Basin , L . Dudley Stamp ,472 .

Equi-dae, No rth America ,

H . F .

Osborn e , 128 .

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564 I n dex .

Ho stette r, J . C. ,Apparatus fo r

growin g Cry stals, 40 Haematitean d Rutile , 427 .

GNEOUS Magmas , Differen tiatio n ,

N, L . Bowen , 86 .

In come - tax ,JohnW Evan s

,192 .

In gredie n ts in Ban ded Bitumin ous

Coal , Marie C. Stop e s, 85 .

In stitute of Min in g an d Metal lurgy ,

233, 522 .

In traTJurassic Moveme n ts in the

Midlan ds , Profe ssor Arthur H . Co x

an d Arthur E . Trueman , 198 .

In ve rte brate Palaeon to l ogy , H . A .

Hawkin s , 469 .

In ve stigatio n o f Loo se Aren ace ous

Sediments, H . A . Bake r, 321 , 363,

4 1 1 , 463.

Iro n Ore Supp l ie s of the World, F. H .

Hatchh504 .

Ore s,Kirun a , R . A . Daly ,

282 .

a_ — ‘

Scotlan d , 468 .

an d Ge o logy ,Min n e sota

,

E . C. Harden an d A . W. John ston,

520 .

Iso static Measure o f Ro cky Moun

tain s , Charle s Key e s, ’

262 .

JACK , H . LOCKHART , Pho sphate s

o f South Australia, 181 .Jackson , J . Wilfrid, Quartzose Co nglomerate , Staffs , 487 .John ston , A . W . , Ge o logy and Iron

o re s Mi nn esota , 520 .

Jurassw Ammon ite s,East Africa ,

L F . Sp ath , 31 1 , 35 1 .

Chro n o logy , S . S . Buckman,

137

ARROO f Rep tile s , S .

Haug hton , 229 .

Kato , Taken ,Me so zo ic Ign e ousRocks ,Ken t , Coalfie ld,

A . E . Ritchie , 375 .

Key e s, Charle s , Isos tatic Measure o f

Ro ckyMoun tain s, 262 .

Kin dle , E. M. , Characteristics o f

Marine'

Clastics , 334 .

in g , W . B . R . , Geo log ical Wo rk o nthe Western Fro n t, 46 Sedgw ick'Mu’se

’

u-m Note s , o n Sp hoerocoryp hethon

'

ison i Reed , 532 .

Kitchin , .

sF. L . , Gault, Le ightonBuzzard, 285 ; Upp er Cretace ousStrata an d Up p e r Gault, Bedfo rdshire , 4 , 52 , 100

Kuroko Ko saka Coppe r’

4Min e s , R .

Ohashi. 283.

ACROIX ,A . , Nephe l in e Rocks ,

185 .

Lamp lugh , G . W Gault n ear

Le ighton Buzzard , 234 .

Lan ey ,F . B . , Ore s o f Ton opah ,

_Nevada

,183.

Lapwo rth , Charle s , an App reciation

195 .

Laterite ,Phy siographic Re latio n s o f ,

W . M. Davis , 4 .

Phy siography o f F . Dixey , 524 .

Lateritization in Sie rra Le on e , F .

Dixey ,2 1 1 .

La Touche ,T . H D .

, SubmergedFore st, Bombay , 376 .

Liassic Ro cks, Somersetshire , Dr .

A . E . Trueman,471 .

Lichfie ld‘

, Ge o logy o f Coun try roun d ,

Ge o l . Survey Memo irs , 423.

Life on Earth , Profe ssor W. M.

Flin ders Pe trie , 47 1 .

Limit betwe en Silurian an d Devon i an

Sy stems, L . Dudley Stamp , 164 .

Li ngu la in the Chalk , R . M. Brydon e ,429 .

Lizard,Be erbachite , Profe ssor T . G .

Bon n ey , 339 .

Lomp o c, Cal iforn ia , Diatomace ous

Earth, Sir Nicho las Yermo lo ff , 27 1 .

AGNETIC Disturban ces in Midlan ds , A . H . Co x , 133.

Man gan e se Ore s , A . H . Curtis , 279 . .1

Map s an d Memo irs of Wil liam Smith ,Thomas Shep pard , 421 .

Marg i n al Drift , 551 .

Marin e Bo rin g An imals, W . T .

Calman , 180 .

Clastics, Characteristl cs of , E . M.

Ki ndle, 334 .

She l ls from San ds an d Grave ls ,

Durham , David Wo o lacott , 307 .

Marl an d Marlin g in Che shire ,

Will iam Hewitt, 46 .

Marr,John Edward ,

P le isto ce n e

Dep o sits, Cambridge , 44

Ske rtchly’

s Ston e Imp lemen ts , 429 .

McEwan ,Eula D . , Brachiop od, g en us

P latystrophia , 88 .

Me lmore , Sidn ey ,Metamorphism o f

Carro ck Fe l l Gabbro ,266 .

Men de l ism an d Palaeon to logy ,Dr .

F . A . Bather, Dr . Ruggle s Gate s ,

Pro fessor J . E . Duerde n , Profe ssor

A . Den dy ,470 .

Me rwin , H. E . , Haematite and Rutile ,

427 Hydrated Ferric Oxide s , 40 .

Me so zo ic Ign eous Rocks , Jap an ,

Take o Kato ,425 .

In dex .

Metamorphism o f Carro ck Fe l l

Gabbro , Sidn ey Me lmore , 266 .

Metamorphism o f Pre - Cambrian Do lomite s, South Austral ia , C. E . Til ley ,

449 , 492 .

Micro chem ical Methods ,Alfred Brammal l

,123.

Midlan ds , Un dergroun d Structure o f ,Pro fe ssor Arthur H . Co x an d

Arthur E Trueman ,198 .

Milburn Group ,Age o f , A . D . N .

Bain,246 .

Mil le r,B . L . , Min e ral Dep o sits ,

South Ame rica, 334 .

Min e ral Chemistry , B o e lter’

s Han d

bo ok , 278 .

Dep o sits of South America ,

B . L . Miller an d J . T . Sin gewa ld ,

334 .

Re source s, Gre at Britain , 336 ,

468 .

Min e ralog ical So ciety ,188 ,

234 , 379 ,

558 .

Min e ralogy , Han dbo ok of, G .

Mon tague Butle r, 18 1 .

Min erals from Bihar an d Orissa , G . H .

Tip p er , 377 .

Min e s o f South Austral ia , 184 .

.Mz'

n in g Electr ica l En g in eer , 530 .

Mo ir, J . Re id , Earlie st Palaeo l ithicFl in t Imp lemen ts , 22 1 .

Mo ly n eux , A . J . C. , Ge o logy of

Sin on ia ,Rhode sia , 183.

Mo ore , Charle s Cl ifton , Obituary o f,527 .

Moren o , Fran cisco ,J . P . , Obituary of ,

95 .

Morpho log ical Studie s o n the Echin o idea Ho lectyp o ida ,

H . L .

Hawkin s , 393.

Whe e lton Hin d , 405 .

Nephe l in e Ro cks, A . Lacro ix , 185 .

Nico l Memorial , 387 .

Nige ria , Nin g i Hills , Ge o l ogy of

Ge rardW . Wil l iams ,434 .

N in g i Hil ls, Ge o logy ,J . D . Falcon er

526 .

NAUT ILOIDS Carbo n ife rous

,

No rthern Nigeria ,

Ge o logy of, Gerard W . Wil l iams ,

Nomen clature o f Heavy Liquids,G . M. Davie s , 287 .

Non - ferrousMin in g ,Rep ort o f, 243.

North , Frederick J Carbon ife rous

Brachiop oda , 136 .

North Devo n , Ge o log ical Structure o f,Dr . J . W Evan s ,

565

ALZEOLITHIC Fl in t Imp lemen ts ,

P J . Re id Mo ir, 22 1 .

Palee on to l og ical Abstracts , F. A .

Bathe r , 19 1Palaeon to l ogy (In vertebrate ) , H .

Wo ods , 44 .

In troductio n to , A . M . Davie s ,

of Arthur

BITUARIES He n ry Charle sBeasley , 94 ; Fran cisco Jo su é

Pascasio More n o , 95 ; Robert

Etheridg e , jun ., 239 ; Walte r R .

Bil l in g s, 287 Ge org e Swe et, 384

Whe e lton Hin d , 476 Sven Le on hardTorn quist , 527 ; Jame s S e rvil le

Ge ikie, 528 Charle s Cl ifton Mo o re

528

Oce an Leve l , Re ce n t Sinkin g o f,W . B

Wright , 382 .

Recen t Worldwide Sin kin g ,

Regin ald A . Daly , 246 .

O’

Con n e l l , Marj orie , Cre tace ous Sil ici

sp on giae , 131

Ord , W . T .

, Gault , Le ighton Buzzard ,

286 .

Ohashi , R . , Kuro ko Kosaka Copp e rMin e s , 283.

Oilfie lds , Mid - Con tin e n tal , T . 0 .

Bo swo rth , 428 .

Old Red San dston e , Glouce stershire ,

T . Fran kl in Sibly , 491 .

Oldhave n Beds , Quartzite Pebble s o i , '

H . A . Bake r,62 .

O’

Ne il l , J . J Econ omic Ge o logy o f

Haze lton ,B .C. , 90 .

Op tical So ciety , 284 .

Ordovician o f Carmarthe n , D . C.

Evan s , 473.

Ore - dep o sits , Differe n tiation an d ,

R . H . Bastal l , 290 .

Ore s o f To n opah , Nevada ,E . S .

Bastin an d F. B . Lan ey ,183.

Osborn e ,H . F . , North .

American

Equidae , 128 .

556 .

Palaeo zo ic Fo ssils in Victoria ,F .

Chapman , 88 .

Till ite s o fNo rth Norway , Olaf

Ho ltedahl , - 372 .

Parkin son ,John , Chan n e l Islan ds ,

4 1 .

Persian Echin o idea ,J .W. Gregory an d

Ethe l Currie ,500 .

Petrie, W . M. Flin ders, Life o n

Earth , 471 .

Pe tro l o gy for Studen ts ,Alfred

Harke r, 43.

Nome n clature

Ho lme s, 426 .

Pho sphate s o f South Austral ia , H .

Lo ckhart Jack , 181

5 66 I n dex .

Picritic Se rp e n tin e n e arWe l ls , Somer

se t, Sidn ey H Reyn o lds

Ple istoce n e Fo ssils from Asphalt -

p its ,229 .

Dep o sits , Cambridge ,Pro fe sso rJ E . Marr

,44 .

Po larized Light in Study of .Ore s an d

Me ta s, F,E . Wright, 521 .

P osidon omyq Beckeri Bron n , var . n ov .

s iamen sis F. R . Cowp e r’

Re ed,1 17

Po sn jak , E . , Hydrated Fe rric Oxide s ,40

Po tash in Un ited State s, H . S . Gal e

an d W . B . Hicks, 281 .

Imp erial Re source s of, 231 .

Pre - Cambrian Do lomite s , South Austral ia , Metamorphism o f, C. E .

Til ley ,449 , 492 .

Pre - Glacial Val ley s o f Arran an d

Sn owdo n , J . W . Gregory , 148 .

Pre side n tial Addre ss Ge o log ical

Section , British Asso ciation ,Dr .

F. H. A . Bathe r, 473.

Pre - Triassic Swall ow - ho le s in the

Haematite District, Furn e ss, Lan e s ,16 .

Prin g le ,J Gault, Le ighton Buzzard ,

285 Up p e r Cretace ous Strata xan d

Upp er Gault , Bedfordshire , 4 ,52

,

Productus humerosas , Distribution of ,in Brachiop od Beds ”

o fMidlan ds ,Prof . T . Fran klin Sibly , 20 .

Pump e l ly ,R . , Excavatio n s in

Turke stan , 557 .

UARTZITE Pebble s o f Oldhave n

Beds, H . A . Baker, 62 .

Quartzo se Co n glome rate, Staffo rd

shiro , F. Barke, Whe e lton Hin d

,

and A . Scott, 76 .J . Wilfred Jacksonan d J . Kay e Charle sworth , 487 .

Quatern ary Dep osits , British , Charle sE . P . Bro oks , 423.

ASTALL, R . H . , Differen tiation

R an d Ore Dep o sits , 290

Raymon d , Percy E . , Pygidium o f

Trilo bite , 22 .

Re ed F. R . Cowp e r, Carbon ife rousFo ssils from Siam , 1 13, 172

Faun a , Devon ian , Torquay , 299 ,

34 1 .

Re id , H . F., Porto Rico Earthquake ,

377 .

Rep tile s o f the Karro o Fo rmation ,

Dr . E . C. N . van Ho ep en , 5 19 .

Rey n o lds, Sidn ey , H . , Picritic Ser

p en tin e at Ebbor, Somerset, 224 .

Richter, Rudo lf, Structure an dHabits

of Trilobite s, 278 .

Rift - Val ley in We stern Persia,

Profe ssor S . Jame s Shan d , 135 :

Ritchie,A . E. ,

Ken t Coalfie ld , 375 .

R ocky Moun tain s , Iso static Measure

of , Charle s Key e s , 262 .

Roy al So cie ty , 283.

ANDS an d Grave ls con tain ing

S Marin e She l ls , Durham ,David

Wo o lacott, 307 .

Sauramo , Matti,Re cen t Glacia l Time

in Fin lan d, 5 18 .

Scott, W . , Quartzo se Con g lome rate ,

Staffs , 76 .

Seward , A . C. , Fo ssil Plan ts, 83.

Sgurr o f Eigg , E . H. Cun n in ghamCraig ,

48 , 190 ; Alfred Harke r, 93,

19 1

Shan d, S. Jame s , A Rift - Val ley in

We stern Pe rsia 135 .

Shepp ard, Thomas , Wil l iam Smithhis Map s an d Memo irs , 421 .

She rlo ck , R . L . , Un bedded Iro n - o re s ,

38 .

Siam , Carbon iferous Fossil s from .

'

F . R . Cowp er Re ed , 1 13, 172 .

Sibly , T . Fran kl in , Dl stribution o f

Productus humerosus Brachiop odBeds o f the Midlan ds , 20

Haematite s of the Fo re st of De an

an d South Wale s, 39 : Haematite in

S outh Wale s, 94 ; Old Red San d

sto n e , Glouce stershire , 471 .

Sierra Le on e , Lateritization in , F .

Dixey ,2 1 1 .

Silurian an d Devon ian Sy stems ,

Limit be twe en , L . Dudley Stamp ,

164

Sin g ewald ,J . T . , Min e ral Dep o sits ,

S . America , 334 .

Sin kin g Ocean Leve l , Re cen t Wo rld

wide ,Reg in ald A . Daly , 246 .

Skertcl i ly’

s Ston e Imp lemen ts , JohnE . Marr, 429 .

Smith , Bern ard ,Pre - Triassic Swal lowho le s in the Haematite District ,

Furn e ss, Lane s , 16 ; Haemat- ite s of'

Furn e ss , 37 .

Warren Dup re, Earthquake s ,Ore g on ,

336 .

Sp ath , L . F . ,Ammo n ite Siphun cl e ,

142 ; Jurassic Ammon ite s , East

Africa, 31 1 , 35 1 ; O n n ew g en us

Day iceras, 538 .

Sp ir ifer, the Gen otyp e o f, S . S .

Buckman , 18 .

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XVI an d 6 4 0 Pag e s , 1 5 0 P l ate s , 1 Map . C lo th .

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HO RA C E B . W O O DW A R D . F .R. S F .G . S .

5 / n et. Fo lded in book fo rm , ne t.

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