114.1.N.

NEW MEXICO GEOLOGICAL SOCIETY

Gu idebook

of the

ALBUQUERQUE COUNTRYE d i t e d b y

Stuart A. Northrop

TWELFTH FIELD CONFERENCEOctober 6, 7, and 8, 1961

N E W M E X I C O G E O L O G I C A L S O C I E T Y * T W E L F T H F I E L D C O N F E R E N C E 1

C O N T E N T S

President's Message .......................................................................................................................................................... 3

Executive and Field Conference Committees .................................................................................................................... 4

Publications of the New Mexico Geological Society .......................................................................................................... 5

Schedule -------------------------------------------------------------------------------------------------------------------------------------------------- 5

A Few Words from the Editor ............................................................................................................................................ 6

Physiographic Setting ........................................................................................................................................................ 7

Photo mosaic maps of Sandia, Lucero, and Jemez areas, central New Mexico ............................... Lowell E. Bogart 8

ROAD LOGS

Sandia Mountains and vicinity

First day, Friday, October 6 ----------------------------------------------------------- Vincent C. Kelley and Charles B. Read 14

West of Albuquerque in the Rio Puerco, Rio San Jose, and Lucero areas

Second day, Saturday, October 7 ------------------------------------------------------------------ V. C. Kelley and C. B. Read 33

Jemez Mountains and vicinity

Third day, Sunday, October 8 ------------------------------------------ V. C. Kelley, E. H. Baltz, Jr., and R. A. Bailey 47

PAPERS

Physiography, c l imate, and vegetat ion of the Albuquerque region ----------------------------------------------------- Roger Y. Anderson 63

Sandia Cave ..................................................................................................................................................................... Frank C. Hibben 72

Indians, ancient and modern, in the Albuquerque country ------------------------------------------------------------------------- S idney R. Ash 75

History of the Albuquerque region ------------------------------------------------------------------------------------------------------------- Frank D. Reeve 82

Chronological resume of some early geologists in the Albuquerque country ------------------------------------- Stuart A. Northrop 85

Absolute geologic t ime scale ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 89

Precambrian rocks of the Albuquerque country ---------------------------------------------------------------------------------- J. Paul Fitzsimmons 90

Pennsylvanian rocks in north -central New Mexico ---------------------------------------------------------------------------- Frank E. Kott lowski 97

Mississ ippian and Pennsylvanian fossi ls of the Albuquerque country ---------------------------------------------------- Stuart A. Northrop 105

Permian st rata of central New Mexico --------------------------------------------------------------------------------------------------------------------- D. L. Boars 113

Triass ic and Jurassic rocks of the Albuquerque area ................................................................ ....................................... Clay T. Smith 121

Cretaceous ro cks of the Albuquerque country .................................................................................................................................................

............................................................................................................................................................................................................................................ 129

Late Cenozoic sediments of the lower Jemez River region ------------------------------------------------------------------------------- Zane Spiegel 132

Out l ine of the geology of the Jemez Mountains, New Mexico ------------------------------ C. S. Ross, R. L. Smith, and R. A. Bailey 139

Structural problems of the Rio Grande trough in the Albuquerque country -------------------------------------------------------- Anonymous 144

The Rio Grande trough near Albuquerque, New Mexico ........................................ H. R. Joest ing, J. E. Case, and L. E. Cordel l 148

Earthquakes of central New Mexico ------------------------------------------------------------------------------------------------------------ Stuart A. Northrop 151

Earthquake research at New Mexico Inst i tute of Min ing and Technology ------------------------- A. R. Sanford and C. R. Holmes 153

The new U. S. Coast and Geodet ic Survey Seismological Laboratory at Albuquerque ---------------------------------------------------------- 154

Mineral resources of Bernalillo, Sandoval, and Santa Fe Counties, New Mexico(exc lusive of oi l and gas) ---------------------------------------------------------------------------------------------------------------------- W ol fgang E. Elston 155

Mineralogical notes on the uranium deposi ts of the Grants and Laguna dist ricts ---------------------------- Abraham Rosenzweig 168

Check l is ts of minerals for mining dist ric ts and other local i t ies near Albuquerque ................................ .... Stuart A. Northrop 172

Petroleum explorat ion in a part of north- central New Mexico ---------------------------------------------------------------- Edward C. Beaumont 175

Ground- water geo logy of the Rio Grande t rough in nor th- cent ra l New Mexico, wi thsect ions on the Jemez caldera and the Lucero up l i f t ------------------------------------------------------------------------ Frank B. Titus, Jr. 186

Abstracts of technical papers -------------------------------------------------------------------------------------------------------------------------------------------------------- 193

IN POCKET

Geo log i c m ap o f t he A lbuquerque c oun t ryb y

Stuar t A . Nor throp and Ar le t te Hi l l

Tec ton ic map of a par t o f the upper Rio Grande area, New Mexicob y

V. C. Kelley

2 N E W M E X I C O G E O L O G I C A L S O C I E T Y % T W E L F T H F I E L D C O N F E R E N C E

N E W M E X I C O G E O L O G I C A L S O C I E T Y <> T W E L F T H F I E L D C O N F E R E N C E 3

PRESIDENT'S MESSAGE

THE BROAD VIEW— — i s impor tant to a l l geo log is ts , regard less of the i rs ta tus wi th in the sc ience, and regard less of the i r degreeof profess ional spec ial izat ion. To provide this view is thed i s t i n c t p r i v i l e g e o f t h e o n l y n o n - a f f i l i a t e d G e o l o g i c a lS o c i e t y s e r v i n g N e w M e x i c o . W e t a k e t h i s s e r i o u s l yenough to consider it a duty.

The Twelf th Field Conference of the New Mexico Geo -logical Soc iety br ings us back f rom far- f lung and compre -hensive forays into the far corners of the State—and someadjacent areas —back to the envi rons of the great popula-t ion center, Albuquerque. Here, through the ef forts of pro -fessional and student geologists, a wide variety of geologic,mineralogic , paleonto logic , and phys iographic informat ionis cont inua l l y updated and expanded. In every d i rec t ion ,new da t a add t o a be t t e r unders t and ing o f f am i l i a rgeo logic features and of their interrelated importance.

Under the ab le gu idance of Char les B. Read of theUni t ed States Geological Survey, 5th pres ident of the So -c i e t y , a s g e n e r a l c h a i r m a n o f t h e C o n f e r e n c e , a n d o fS t u a r t A . N o r t h r o p o f t h e G e o l o g y D e p a r t m e n t a t t h eUniversity of New Mexico, 3rd president of the Society, ase d i t o r o f t h e G u i d e b o o k , we wi l l h a v e a n a u t h o r i t a t i v el o o k a t a v a r i e t y o f f e a t u r e s a t t h e v e r y h e a r t o f N e wMexico geo logy. The t r ip leaders and the gu idebook au -thors are outs tanding students of thei r phases of geologicinterest and of their areas of investigation.

T o e v e r y g e o l o g i s t i n N e w Me x i c o , a n d i n t h e s u r-round ing ter r i to ry , th is Conference wi l l be a va luab leexper ience in re -or ienta t ion , and the gu idebook wi l l bean indispensable addition to his professional library.

The committee's ingenuity in operating this Conferencefrom Albuquerque as a hub, wi th a return to the c i ty eachevening, works to the advantage of al l part ic ipants .Scheduling on a week end permits more of our friends towhomgeology is an avocat ion to come "rock- hounding"wi th us. Th is is an idea l f ie ld t r ip in many re spec ts . W e

express our gra t i tude to the many commi t tee members ,authors , and tr ip leaders whose ef forts make i t so. Muchwork was done, also, by members who shared the seriousresponsibil it ies of the Society, but whose names do notappear in these formal listings.

These conscient ious workers f ind their reward in yourenthusiast ic attendance, and your appreciat ive acceptanceand use of the gu idebook . They ga in , a lso , in ab i l i t y andef fec t i veness in the i r own f ie ld of endeavor through theexper ience of th is cooperat i ve ef for t . Th is is the way anef fec t i ve sc ient i f i c soc ie ty works , and th is is the reasonit is effective.

The members of the executive committee welcome you.W e know you wi l l enjoy the comradeship and discuss ionswi t h f r i ends o f m u t ua l i n t e res t . W e be l i eve you wi l l beinsp i red by inspec t ion of geo log ic phenomena f rom Pre -cambrian to Recent , and from strat igraphic and st ructuralt o i gneous and m ine ra l i zed . W e hope you wi l l bes t im u la ted by the inv igora t ing c l imate f rom warm, lowdeser ts to cool, majestic pine-clad mountains.

Jo in us , too, next May at our Techn ica l Meet ing inAlbuquerque . And p lan ahead for our next F ie ld Confer -ence . Our de layed p lans wi th the Ar izona Geolog ica lSo ciety should develop, and wil l take us into the "TontoRim" count ry f rom wes ternmos t- cent ra l New Mexico in toeas t - central Arizona.

Richard D. Holt, PresidentNew Mexico Geological Society

EXECUTIVE COMMITTEERichard D. Hol t Pres ident Humble Oil and Refining Co.

Elmer H. Bol tz, Jr . V ice-Pres ident

Frank B. Ti tus, Jr . Secretary

W ol fgang E. Els ton Treasurer

Frank E. Kot t lowsk i Past Pres ident

U. S. Geological Survey, Water ResourcesDivis ion

U. S. Geological Survey, Water ResourcesDivis ion

Department of Geology, Univers i ty of NewMexico

New Mexico Bureau of Mines and MineralResources

FIELD CONFERENCE COMMITTEES

Charles B. Read General Chairman U. S. Geological Survey, Paleontology andStratigraphy Branch

Guidebook CommitteeStuart A. Northrop Edi tor Department of Geology, University of New

Mexico

Road Logging CommitteeVincent C. Kel ley Chairman Department of Geology, Univers i ty of

New Mexico

Roy A. Bai ley U. S. Geological Survey

Elmer H. Bal tz, Jr . U. S. Geological Survey, Water ResourcesDivision

Registration CommitteeFreder ick J. Kuel lmer Chairman New Mexico Bureau of Mines and Minera l

Resources

Caravan CommitteeCo- Chairman New Mexico Bureau of Mines and Mineral

Resources

Co- Chairman Humble Oil and Refining Co.

Advertising CommitteeChairman Pubco Petroleum Corp.

Finance CommitteeDepartment of Geology, Univers i ty of New

Mexico

Catering CommitteeS. Eugene Buel l Chairman U. S. Geological Survey, W ater Resources

Division

4 N E W M E X I C O G E O L O G I C A L S O C I E T Y * T W E L F T H F I E L D C O N F E R E N C E

Frank E. Kottlowski

Sam Thompson, Ill

James L. Albright

Wolfgang E. Elston

PUBLICATIONS OF THE NEW MEXICO GEOLOGICAL SOCIETY

1 . G u i d e b o o k o f t h e S a n J u a n B a s i n [ c o v e r i n gn o r t h a n d e a s t s i d e s ] , N e w Me x i c o a n d C o l o-rado ; F i r s t F ie l d Con f e renc e , 1950 ; ed i t ed byV incent C. Ke l ley and others ; 153 pages , 40 i l -lustrations. (Out of print)

2 . Gu idebook o f t he s ou t h and wes t s i des o f t heSan Juan Bas in , New Mexico and Ar izona; Sec -ond F ie ld Conference, 1951; ed i ted by Clay T.Sm i th and Caswel l S i l ver ; 163 pages , 69 i l lus -t ra t ions . (Out o f pr in t )

3 . Gu idebook o f t he R io Grande c oun t ry , c en t ra lN e w Me x i c o ; T h i r d F i e l d C o n f e r e n c e , 1 9 5 2 ;edited by Ross B. Johnson and Charles B. Read;126 pages, 51 illustrations. (Out of print)

4 . Guidebook of southwestern New Mexico; FourthField Conference, 1953; edi ted by Frank E. Kot -t lowsk i and others ; 165 pages , 67 i l lus t ra t ions .$5.00

5 . Gu idebook o f s ou t heas t e rn New Mexi c o ; F i f t hF ie ld Conference, 1954; ed i ted by T. F . S t ipp;213 pages, 83 illustrations. $5.00

6 . Guidebook of south- cent ra l New Mexico; S ixthF ie ld Conference, 1955; ed i ted by J . Pau l F i t z -s immons; 193 pages, 70 i l lus t rat ions. Preparedwi th the cooperat ion of the Roswel l Geolog ica lSoc ie ty . $7.00 (Only a few copies le f t )

7 . G u i d e b o o k o f s o u t h e a s t e r n S a n g r e d e C r i s t oMountains, New Mexico ( Raton Basin); SeventhF ie ld Conference, 1956; ed i ted by A. Rosenz-weig; 154 pages, 61 illustrations. $7.00

8 . Guidebook of southwestern San Juan Mountains,Colorado ( Four Corners Area); Eighth Field Con-ference, 1957; edited by Frank E. Kottlowski; 258pages, 109 illustrations. $7.00

9 . Guidebook of the B lack Mesa Bas in , nor theas tAr izona; Nin th F ie ld Conference, 1958; ed i ted

by Roger Y. Anderson and John W. Harshbarger;205 pages , 105 i l lus t ra t ions , hard b ind ing. Pre-pared in cooperat ion wi th the Ar izona Geolo -gical Society. $8.50

10. Guidebook of west-central New Mexico; TenthField Conference, 1959; edited by James E. Weir,J r . and E lmer H. Bol t z , J r . ; 162 pages , 83 i l lus-trations, hard binding. $8.50

11. Guidebook of Rio Chama count ry [New Mexicoand Colorado]; Eleventh Field Conference, 1960;ed i ted by Edward C. Beaumont and Char les B.Read; 129 pages, 35 i l lus t rat ions, hard binding.$8.50

12. G u i d e b o o k o f t h e A l b u q u e r q u e c o u n t r y [ N e wMexi c o ] ; Twe l f t h F ie l d Con f erenc e ; ed i t ed byStuart A. Northrop; hard binding. $ 9 . 5 0 .

These publ icat ions are avai lable by mai l (p lease add 25¢f o r hand l i ng and pos t age ) f rom t he New Mexi c o Bureauof Mines and Mineral Resources, Campus Stat ion, Socorro,New Mexi c o . A l s o ove r -t he -c oun t e r s a les a t e i t he r t heBureau of Mines or the Department of Geology, Univers i tyo f N e w Me x i c o , A l b u q u e r q u e . C h e c k s s h o u l d b e m a d ep a y a b l e t o t h e N e w Me x i c o G e o l o g i c a l S o c i e t y . G e o l o -g i c m a p s a c c o m p a n y i n g c e r t a i n g u i d e b o o k s a r e a v a i l-ab le by mai l o r over the counter a t the Bureau of Mines ,Socorro, as follows:(a) Geolog ic map of the S ier ra County reg ion, New Mex -

i c o ; c om p i l ed by V inc en t C . Ke l l ey ; ac c om pan iesGuidebook of the Sixth Field Conference. $1.00

( b ) Geo log i c m ap o f t he R io Cham a c oun t ry ; c om p i l edby C lay T . Sm i t h and W i l l i am R. Mueh lbe rge r ; ac-companies Guidebook of the Eleventh Field Confer-ence. $0.50

(c ) Geolog ic map of the A lbuquerque count ry ; compi ledby Stuart A. Northrop and Arlet te Hi l l ; accompaniesGuidebook of the Twel f th F ie ld Conference. $1.00

0

Thursday, October 55:00 - 10:00 p.m.

Friday, October 67:30 a.m.

SCHEDULERegistrat ion, New Mexico Union, University of New Mexico Campus, Albuquerque,

New Mexico.

Caravan assembles on East Central (U. S. 66 -East) at Juan Tabo Road.

Saturday, October 7 Caravan assembles on West Central (U. S. 66-West), 3 miles west of Rio Grande7:30 a.m. bridge.

Sunday, October 8 Caravan assembles on San Mateo Blvd., N.E., at Montgomery Road.7:30 a.m.

Field Conference ends near Santa Fe.

N E W M E X I C O G E O L O G I C A L S O C I E T Y • T W E L F T H F I E L D C O N F E R E N C E 5

0

6 N E W M E X I C O G E O L O G I C A L S O C I E T Y * T W E L F T H F I E L D C O N F E R E N C E

A FEW WORDS FROM THE EDITORA g l a n c e a t t h e a c c o m p a n y i n g g e o l o g i c m a p ( i n

p o c k e t ) w i l l r e v e a l t h a t A l b u q u e r q u e i s n o t a t t h e g e o -g r a p h i c c e n t e r o f t h e m a p - a r e a . O n e o f t h e c h i e fr e asons for th is is that the U. S. Geological Survey'srevised map of the nor theas tern quar ter o f the State hasnot yet been publ i shed. The map f rom which theGuidebook map was compi led is Dane and Bachman's(1957) "Prel im inary geo log i c m ap o f t he nor t hwes t e rnpa r t o f New Mexi c o " (U. S . Geol . Survey Misc . Geol .Inv . Map 1- 224) , wh ich dis t inguishes more than 78strat igraphic uni ts . I t seemed to some of us that a mapdes igned for use on a f ie ld con f e renc e , i n c on junc t i onwi t h a road log , s hou ld be k ep t as s imple as poss ible.Thus, the Guidebook map employs on l y 10 s t ra t i g raph i cun i t s . ( I n t he p lann ing s t ages , we refer red to our mapas a "60- m i le- an -hour map. " )

I t has not been poss ib le to cover a l l aspec ts of thegeo logy o f t he A lbuquerque c oun t ry i n t h i s Gu idebook .T h e G u i d e b o o k d o e s n o t p r e t e n d t o b e a c o m pe n d i u mo f a l l t h a t i s k n o wn o f t h e g e o l o g y o f t h e a r e a . Ma n ys ign i f i cant facets are desc r ibed in one or more chapters ,but several short art ic les might have been prepared to dealwi th cer ta in other aspec ts . The geolog ic l i t e ra ture isvo luminous and many important publ ished papers areneither c i ted in the text nor even inc luded in the severa ll i s t s o f re f e renc es . A t one t im e we t hough t o f c om p i l i nga c om plete bibl iography —a sort of master bibl iography—for the Guidebook , but th is would have enta i led so muchrepet i t ion that we abandoned the idea.Geographic Nam es . —Map- m ak ers s eem t o de l i gh t i nchang ing geograph ic names in the Southwes t . Note thefol lowing changes in names of certain features in the areaon U. S. G. S. maps f rom 1928 to 1960.

Darton's Geologic Map New Mexico Base Map(1928) (1960)

Ladron Pk Ladron MtsMesa Chivato Cebolleta MtsNacimiento Mts Sierra NacimientoSan Pedro Mtn San Pedro Mountains

(near Cuba) [error]

San Pedro Mts [not named](near Golden)

Valle Mts Jemez Mountains

The Ladron Mountains, jus t south of the south edge of theGuidebook map, have a lso been refer red to as S ier ra La-d ron and S ie r ra Ladrones . The J em ez Moun t a ins havebeen cal led the Sierra de los Val les ; the lat ter term isproper ly appl ied to only a part of the mountainssurmount ing the Jemez Plateau. The great depress ion atthe summit of the Jemez Pla teau has been ca l led Jemezcra ter , Jemez ca ldera , Va l les c ra ter , Va l les ca ldera , andis of ten re fer r e d t o b y m a n y l o c a l p e o p l e a s t h e V a l l eG r a n d e . A c t ual ly, Val le Grande is simply one of severalval leys occupy ing the caldera, as pointed out by Ross,Smith, and Bailey in their article in the Guidebook.

Editor ial Pol icy. —Edi tor ia l pol ic ies and pract ices changecont inual ly. In some of the Society 's guidebooks, the edi -tors have given contr ibutors a f ree hand, espec ial ly in theformat o f c i t ing re ferences . In v iew of the commendableat tempts in recent years to s tandard ize the order o f c i ta-t ion in bibl iographic l is ts (see "Suggest ions to authors oft he repo r t s o f t he U. S . Geo log i c a l Su rvey , " 5 t h ed . , p .107) and a lso to s tandard ize the abbrev ia t ions used inc i t a t i o n s ( i b i d . , p . 1 1 1 - 1 1 8 ) , y o u r e d i t o r h a s m a d e ava l ian t a t tempt to ach ieve some degree of un i fo rm i ty int h i s G u i d e b o o k . H e a p o l o g i z e s t o c e r t a i n a u t h o r s f o rmaking extens ive al terat ions in format , espec ial ly in thei rl i s t s o f re ferences . Prac t i ca l l y every re ference has beenchecked for the name of the author, the date, the t i t le, thesource (per iodical , ser ies , etc . ) , the volume number, andpages. The bibl iographies are thus bel ieved to be relat ive -ly free of errors.

Inc identa l l y , the ed i tor has not fo l lowed Geolog ica lSurvey s ty le in every par t i cu lar . For example , he pre fers"New Mexi c o " t o t he Survey ' s f am i l i a r abb rev ia t i on "N.Mex. " He does not care for the Survey 's use of "N. Mex.Univ . " , but pre fers "Univ . New Mexico" ( par t l y becausethe institution near Las Cruces now calls itself "New MexicoS t a t e U n i v e r s i t y " ) . H e h a s g e n e r a l l y s h o r t e n e d " N e wMexico Inst i tute of Mining and Technology S tate Bureau ofMines and Mineral Resources" to "New Mexico Bur. Minesand Mineral Res." The editor has a dist inct aversion to therecent ly adopted capital izat ion of strat igraphic terms, suchas s ys t em , g roup , and f o rm a t i on , i n "Perm ian Sys t em , ""Santa Fe Group," "Madera Limestone." Again, the edi torsees no necessity for the hyphen in such color terms as "lightgray" or " redd ish brown" when used as modi f ie rs beforethe noun. On the other hand, he has retained the hyphenin s uc h t e rm s as "o l i ve - g reen" and "choc o la t e - b rown . "(The reader wil l f ind some inconsistencies in hyphening ofcolor terms between chapters edited early and those editedlate. ) W ri ters have been al lowed individual preference ins om e c as es ; s om e pre f e r "Abo Pas s " and o t he rs , "Abopas s ; " s om e pre f e r "Sand ia Cres t " and o t he rs , "Sand iac res t . " Some prefer "a l igned" and others , "a l ined. "

The Geological Survey has long frowned on citat ion oftheses and dissertat ions on the grounds that "unpublishedt hes es genera l l y a re no t c onven ien t l y ava i l ab le . " How-ever , such mater ia l i s now becom ing ava i lab le in m ic ro-f i lm f o rm . I n t h i s Gu idebook f requen t c i t a t i on o f unpub-l ished theses is made. W e bel ieve that such a great s tore -house of information should not go unmentioned.

Every paper subm i t ted for the Guidebook has beenread by Charles B. Read, and the editor has prof i ted great -ly by his long experience with f ield conferences and guide -books.

Stuart A. Northrop

NEW MEXICO GEOLOGICAL SOCIETY <> TWELFTH FIELD CONFERENCE

7

PHYSIOGRAPHIC SETTINGAccording to the well-known Fenneman map, "Physi-

cal Divisions of the United States" (U. S. Geol. Survey,1930), within a radius of 90 miles of Albuquerque thereare three major physiographic divisions, four provinces,and seven sections, as follows:

INTERIOR PLAINS major divisionGreat Plains province

Raton section (13g)Pecos Valley section (13h)

ROCKY MOUNTAIN SYSTEM major divisionSouthern Rocky Mountains province (16)

(not subdivided into sections)INTERMONTANE PLATEAUS major division

Colorado Plateaus provinceNavajo section (21d)Datil section (21f)

Basin and Range provinceMexican Highland section (22d)Sacramento section (22e)

Characteristics of the sections are as follows:Raton section: trenched peneplain surmounted by dis-

sected lava-capped plateaus and buttes.Pecos Valley section: late mature to old plain.Southern Rocky Mountains province: complex moun-

tains of various types; intermont basins.Navajo section: young plateaus; smaller relief than

the Canyon Lands section (21c) of Colorado and Utah.Datil section: lava flows entire or in remnants; vol-

canic necks.Mexican Highland section: isolated ranges ( largely

dissected block mountains) separated by aggraded desertplains.

Sacramento section: mature block mountains of gen-tly tilted strata; block plateaus; bolsons.

The only section well represented in the State thatdoes not approach to within 90 miles of Albuquerque isthe High Plains (13d), about 150 miles east of Albu-querque. The Canyon Lands section (21c) barely entersthe State at the northwest corner; this is about 175 milesfrom Albuquerque.

Note that the Rocky Mountains terminate betweenSanta Fe and Las Vegas, despite a National GeographicSociety map that shows them extending clear across NewMexico and terminating in West Texas. (It is reliably re-ported that the reason for this was that the Society hadmany members residing in Texas who liked to think thattheir State included a bit of the Rockies! These people stillinvade New Mexico and Colorado to fish.) Of course,it all depends on the point of view. Structurally, theSandia-Manzano Range may partake of some of the charac-teristics of the Southern Rocky Mountains province, butFenneman's classification stresses physiography, and theRio Grande depression, the Sandia-Manzano Range, andthe Estancia bolson certainly resemble Basin and Rangephysiography—with "isolated ranges ( largely dissectedblock mountains) separated by aggraded desert plains."

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Scale 7 000 00000

300 KILOMETERS

Physiographic divisions of New Mexico.Adapted from Fenneman (1930).

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Sur. MILES

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