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JULY/AUGUST 1992

~ALIFORNIA

GEOLOGY

CALCAREOUS TUFA FORMATIONS

California's GeologyOUf Resources - Our Hazards

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CHANGE SYMPOSIUM ANNOUNCEMENT .CALCAREOUS TUFA FORMATIONS .GEOMETRY OF NORMAL FAULTING IN TECOPA VALLEY.

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JULY/AUGUST 1992Nolume 45.Number 4CGEOA 45 (4) 97132 (1992)

Cover photo: Expos&d lula formations along shoreline 01 MonoLake. South Tufa Area, Mono Lake Tufa State Reserve. Photo byTed Rl9fJef.

" CAliFORNIA GEOLOGY JULY/AUGUST 1992

CALCAREOUS TUFA FORMATIONSSearles Lake and Mono Lake

TED RIEGER, Writer and Photographer

Photo 1. Tufa spires al South Tufa Area, Mono Lake Tula State Reserve. Narrowed diameters on two Spires at lelt indicate a formerlake surlace where tufa was reduced, possibly by waves or solution 10 lake water. Photos by author.

INTRODUCTION

Tufa fonnallons. while not unique to1 California. are represented here by

some of the most picturesque and diverseexamples knovm (front cover and Photo 1).Tufa. often called calcareous tufa. is a sedi­mentary rock composed of calcium car­bonate Oimestone) deposited as calcite.aragonite. or high-magnesium calcite.ll1e hard. dense variety of tufa is travertine.Tufa has been quarried and cut for buildingstone. most notably from sources in Italy(Putnam. 1971). but extraction of tufa inCalifornia has been limited.

Tufa deposits occur in several forms.and the factors and variables involvedin tufa formation may differ by location.Although substantial research has beendone on the subject. particularly at Mono

Lake, the specific mechanisms for tufaformation are still not fully understoodHowever, the basic process for the forma­tion of tufa tOVJel'S and pinnacles is dis·cussed below.

Calcareous tufa forms underwater insaline or alkaline lakes when calcium­bearing spring water wells up from thelakebed. When the caklum-containingspring water comes in contact with car­bonate in the lake water, precipitation inlocalcium carbonate, or the formation oftufa. occurs around the opening of thespring (F"Igure 1). Although springwatertemperature may influence tufa formation.deposition can occur wilh geolhermal orcold'water springs. Lake level fluctuationinfluences tufa formation by altering themineral concentration in the lake waterand can also change the rate and location

of springwater discharge from a tufa forma­tion. Receding lake levels eventually halttufa deposition. leaving exposed formationsappearing as towers. cones. domes. ridges.knobs. or more intricate shapes.

Tufa deposits also occur as pavementsor concretionary deposits in sedimentaryIakebeds, and along shorelines of alkalinelakes througllout the v..rorld. Tufa is some·times found in terraces of fonner shore­lines that have been exposed by evapora­lion or by receding lake waters. Calcium­bearing streams and rain runoff may alsocontribute to tufa precipitation in somelocations. Another form. sand tufa. foundat Mono Lake in intricate structures 01calcite-impregnated columns, tubes, andolher configurations. forms beneath andadjacent to the lake in sands and silts satu·rated with brine.

CALIFORNIA GEOLOGY JULY AUGUST 1992 99

For many years. published researchhas discussed whelher tufa is formed byphysicochemical precipitation. biologicalprecipitation. or a combination of thesetlNO processes. Algal remains in olclerexposed tufa, and the occurrence of algae\.Vith freshly formed tufa at Mono U1ke,raise the issue of the role of algae in tufaformation. Researchers differ as towhether algae playa biological role. beingrequired to form certain types of tufa. or ifalgae only affect tufa structure and tex­ture. and possibly enhance tufa precipita­tion that VJOU1cI also occur without theirpresence. Although deposition of sandtufas and concretionary deposits appearto be purely physicochemical. there areindications of biological innuences on thedeposition of tufa towers. particularly inshalloYJer lake water.

Ongoing research reveals potentialinfluences on the fonnation of tufa, andthere are indications that tufa, undercertain conditions, can precipitate andbuilcl deposits faster than was previouslyknown. The present understanding of tufaprecipitation is perhaps best summarizedby the obselVations of David Herbst(Sierra Nevada Aquatic Research Labora­tory [University of Californial. MammothLakes. California. oral communication.1992) and Scott Stine (California State

University. Hayward. oral communication,1992) who have stated that it appears tobe more complex than simply the mixingof spring water \.Vim lake water.

TUFA APPEARANCEAND STRUCTURAL TYPES

The exposed tufa lormations discussedin this article generally have the surfaceappearance and texture of ","ite. tan. lightgray, or cream-colored porous limestone.Russell (1883. 1889) was one of the firstto describe tufa rype:s based on structuralvarieties and age of deposition. from hisobservations of weathered cross sectionsof formations at Pyramid Lake and MonoLake. He described three basic typeS:lithoid. dendritic, and thinolitic. Uthoidtufa forms the inner core of a tufa fonna­tion. or the entire fonnation. It has beendescribed as a stony variety. and may formas porous and tubular masses. Dendritictufa has a structure of tightly packed col­umns of upward branching stems.Thinolitk tufa is made of thinolite (a vari­ety of cakite) that appears as tetragonalpyramids that can form a IatUce-l.VOrkcrystalline deposit. All three typeS canoccur in layers of varying thicknesses toform a tufa tOYJer. While the central coreof a tOVJer is always a lithoid variety. thesubsequent order of dendritic and thinolilic

layers can vary. and there may be morethan one layer of each of the threevarieties.

REGIONAL GEOLOGIC HISTORY

In California. tufa is associated withPleistocene lakes and dry lakes of theBasin and Range province. Water levels01 these lakes have nuctuated duringgeologic history due to variations in pre­cipitation and glacial melt runoff fromthe Sierra Nevada during the Pleistoceneice ages. During \.Vetter periods. theselake basins overflowed and fed oneanother from runoff flowing north tosouth from western Nevada through theMono Basin and the Owens Valley.through China Basin and Searles Basin.then into Panamint Valley and DeathValley (Plgure 2). These lakes. most ofwhich are dry. are also associated with theformer Lake Lahontan system of thePleistocene that ranged across the GreatBasin to the Great Salt Lake in Utan.During the ice ages. vast Inland seas filledthe troughs between mountain ranges.Wlthout outlets. the basins accumulatedsaline and alkaline minerals thaI formedthick sedimentary deposits. Evaporationhas concentrated saline and alkaline min·erals in the rernaining lakes. as in MonoLake and the Great Salt Lake.

1941 lake level~ --------------------, I

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Tufa towers

Present lake level

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clllt:Ium bftrlng spring waler

Figure 1. Stylizedcross S6C\lon otMono Lake showingtula deposition byInteraction 01 lakeand sPfing water.Tops ot tuta spires atleft ma~ the lake'slevel in 1941. Cour­tesy of the CalrlormaDepartment of Parksand RecreatIOn.

'" CALIFORNIA GEOLOGY JULY AUGUST 1992

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CALIFORNIA GEOLOGY JULY/AUGUST 1992 '"

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The locations of tufa formations atSearles Ulke and Mono Lake present aninteresting contrast in present-day condi­tions. The tufa known as the Searles Lakeor Trona Pinnacles occurs at the southemend of Searles Lake, a playa or drylakebed in northwest San BernardinoCounty. The youngest of these pinnaclesare estimated to have formed at least10_000 years ago. At Mono Lake. inMono County near Lee Vming. whichholds the largest volume of water of anynatural lake entirely within California. theprocess of tufa formation still occurs.GoOO examples of tufa domes. towers.and terrace deposits are also found atPyramid Lake. Nevada. another GreatBasin Jake of Pleistocene origin. Tufadeposits have also been found in the$alton Trough in southern California. andat a number of alkaline Quaternary lakesof the Great Basin.

Figure 3.locallOn map 01 the Trona Pinnacles tufa area.DISCUSSION OF SEARLES LAKE

PINNACLES OR TAONA PINNACLES

locatiOfl and Distribution of Pinnacles

Photo 2. Northern group 01 Trona Pinnacles With casteltated summit 01 ridge pmnacle, andsmaller tower pmnacres to the nghl.

The Trona Pinnacles tufa area is 10miles (16 km) south of the town of Tronaand 20 miles (32 km) east of Ridgecrest(Photo 2 and rtgure 3). The pinnacles arevisible from State Highway 178 betweenRidgecrest arK! Trona south of the high-

way, and reached by a graded dirt roadthat meets Highway 178 about 7.7 miles(12 km) east of Its junction with theTrona-Red Mountain road. Trona Pin­nacles. designated a National NaturalLandmark by the U.S. Department of the

Interior in 1968, is managed by theBureau of Land Management (BLM) asan Area of Critical Environmental Con­cern within the California Desert Conser­vation Area.

There are about 500 tufa spiresspread over the Trona tufa area, which isroughly 4 miles (6 km) wkIe by 10 miles(16 km) long. They range in height from1 to 140 feet (0.3 to 43 m), averaging10 to 40 feet (3 to \2 m). Basal wkiths ordiameters range up to 500 feet (150 m),but average only 20 to 30 feet (6 to 9 mI.They occur at the south end of SearlesBasin in what was an arm-like bay on thesouthVJeSt side of the former lake. andgenerally straddle what is now TeagleWash (Hgure 4). SchoU (I %0) noted thatthe occurrence of tufa formation indicatesthat tufa precipitated arourK!the OOllcesof springs issuing along the strikes offaullS in the igneous and metamorphicrocks that underlie the lacustrine (Iake­deposited) sediments.

The pinnacles occur in three separategroups varying in age arK! elevation.The southem group is the oldest andcorresponds to the Iake's highest eleva­tion of 2,260 feet (690 m) during theTahoe ice age (\>etw€en 100.000 and32.000 years ago) (Scholl, 1960). Atlhis

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EXPLANATION..,.."1.-:.-."-....location 01 pinnacles

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Pinnacle Shapes and Structure

Generally, the pinnacles riseverticaUy from gently slopingbasal mounds composed ofsublacustrine talus material andmore recently eroded tufa talus.Scholl (1960) has classified thepinnacles into four generalshapes-tower. tombstone. cone.and ridge (Photos 2 and 3). ThetOVJer structures occur in all threegroups. and are among the mostcommon and noticeable type. withroughly circular horizontal crosssections and summits that may bepointed. rounded. or flat. Theirheights exceed their diameters.The tombstone pinnacles occuronly in the northern group andare characterized as ellipsoidalin cross section. Scholl's cone typeis actually a mound structure thatoccurs in all three groups and isthe smallest and shortest type.commonly fewer than 10 feet(3 m) high. The rXige type of tufais the most massive. Only three ofthese structures exist in the Tronaarea---one in the northern groupand two in the middle group. Onein the middle group is 800 feet(240 m) long. 500 feet (150 m)VJide. and 140 feet (43 m) high.making it the tallest and largesttufa formation in the area.

Figure 4. Sketch map showing distribIJtion of most 0' the pinnacles at the southwest end otSearles Basin; however, less than hall of the pinnacles in the southem group are shown. Thetwo enlarged black areas in the middle group are the large hmestone ridges. From SCholl (1960).

time. Searles Lake reached its maximumdepth of 640 feet (195 m) (Blanc andCleveland, 1961). and was connected tothe west with waters of China Basinthrough Salt Wells Valley. where weath­ered tufa towers are also found at eleva­tions of 2.200 to 2.260 feet (670 to690 mI. lhe southern group of TronaPinnacles contains about 200 formationsthat range from 1 to 25 feet (0.3 to 8 m)high and 5t040 feet{1.5 to 12m)indiameter. These are the mosl severelyv.oeathered and many are damaged from

blasting activity (Scholl. 1960). Theyrange in elevation from 2, 100 to 2.260feel (640 to 690 m).

lhe middle and northern groups areyounger and more similar in age, Theyfonned during the TIOga ice age between25.000 and 10.000 yoears ago. whenLake Searles had a maximum depth of460 feet (140 m) and lake level elevationof 2.000 feet (610 mI. The middle groupcontains about 100 fonnations and thenorthern group about 200,

Scholl (1 %0) states that thesizes and shapes of the pinnaclesprobably reflect the size. flow.and chemical composition of thesprings, the spacing of the springs.the depth of lake water. and therate of rise or fall of the lake level.Tombstone and ridge structuresmay have developed around anumber 01 closely spaced springsof higher flow: lower and cone

pinnacles developed around one or justa lew springs.

While the Trona Pinnacles wouldprimarily be classified structurally aslithoid. Scholl (1960) has adaptedRussell's terms and added his ovm to lislseven tufa classifications at Searles Like.They are: 1) stony lithoid-a porousand somewhat cavernous cream-coloredtufa; 2) cavernous lithoid-a highlyporous cream-colored tufa: 3) massivelithoid-a Jight-gray somewhat porous

CALIFORNIA GEOlOGY JULY/AUGUST 1992 '"

Photo 3. Tombstone pinnacles in nonhem group ot Trona Pinnacles.

compact tufa; 4) dendrmc-a ratherdense branching or arborescent tufa;5) nodose---a cream-colored tufa: and6) tubular-a chalk-white to cream-col­ored tufa v..rhich grades upward into7) Iobate-a banded tufa.

Buried tufa deposits within fine-grainedto gravelly lacustrine sediments are alsoexposed on the northern side of thenorthern pinnacles as bedded Iens-shapeddeposits 5 to 15 feet (1.5 to 5 m) thick.They are composed of stony lithoid

tufa. While there have been no reportsof thinolitic tufa in the Searles Lake area,Cloud and Lajoie (l980) report thatsand tufa structures have been observedin older deposits in the Searles Valleythat were interpreted as okIer shorelineindicators.

Scholl maintains that algae were princi­pal agents causing deposition of tufa althe Trona Pinnacles (1 %0) and at MonoLake (Scholl and Taft. 1964). Based onmicroscopic examinations 01 pinnacle tufa

sections, Scholl found abundant smallellipsoidal to polygonal bodies that hebelieve:! to be molds of algal cells. Henoted thai these occurred primarily in thestony and cavernous lithoid tufas whichconstitute between 50 and 95 percentof most of the pinnacles. While he con­cludes that cakium carbonate '<NOUId haveprobabloy accumulated without the aid ofalgae. it may not have been in the fonnof pinnacles (Scholl, 1960).

Uses 01 Trona Pinnacles. searles lake

Trona Pinnacles, in particular thenorthern group. have been a filming loca­tion for science fiction and fantasy moviesbecause of the bizarre landscape. Thepinnacles were seen in the Star Trek Vmovie. and have also been used for musicvideos. 1V commercials, and magazinemodeling layouts. BLM personnel reportthat shafts have been drilled at the basesof some pinnacles for unknown reasons,but it appears Ihat only the southerngroup, which shows signs of VJeatheringand blasting activity. has been quarriedcommercially for limestone (BLM. 19721.TI'IC pinnacles tufa is now protected frommining and collecting activity. Nearby, thedry lakebed of Searles Lake has been lhesite of commercial extraction and process­ing of mineral brines-including borax.potash. sodium carbonate. sodium sulfate.potassium chloride, lithium carbonate, andbromine--dating back to 1874. Kerr­McGee (])emical Corporation extractslake deposits and operates processingfacilities at Trona.

The northern group is the I1lOSt acces­sible by a dirt road suitable for 2-wheeldrive vehicles. Ho.vever. the road shouldnot be used in wet VJeather. A 1f2-mileloop trail takes hikers through this groupof pinnacles. BLM's Ridgecrest office canbe contacted for further infonnation onvisitation and recreation at the pinnacles.

DISCUSStON OF MONO LAKETUFA FORMATIONS

LocalJon, Age. and FormerLevels 01 Mono lake

Mono Lake is in a basin below theeastern escarpment of the Sierra Nevada(cover phOIO, Pflo(o 4). "The lake andbasin area is OOrdered roughly on the VJeStby Highway 395. on the north by High~

way 167, and on the south by Highway120 (Figure 51.

". CAUFOANIA GEOLOOY JULY/AUGUST 1992

Mono Lake. dated to 730.000 yearsago. is one of lhe oldest continuouslyexisting lakes in North America. While thelake level has fluctuated throughout itsexistence. it reached its maximum depthof over 900 feet (275 ml when MonoBasin was filled by Pleistocene LakeRussell to an elevation of 7.ISO feel(2.190 m). covering 338 square miles(875 km7J. This level may have occurredmore lhan once during glacial advances ofthe Tioga ice age. 12.500 to 22.000years ago (Mono Basin Ecosystem SrudyCommittee. 1987), The Jake is believed tohave reached its lowest level (6.365 feetor 1.941 m) during the past 5.000 years.but it probably contained a higher volumeof waler than it VJOllId today at the sameelevation. Since first recorded in 1857 atan elevation of 6.407 feet (L954 m). lakelevels have reached a high of 6.428 feet(1.960 m) in 1927 and a b.vof6.372feet 0.943 m) in 1982. Auctuations aredue to waler diversions from tributarystreams by the Los Angeles Departmentof Water and PQV.Ier. wet winters. anddrought. The lake level is 6.374.5 feet0.944.2 mJ (April 1992) with a maxi­mwn depth of about 150 feet (45 m).

Tufa Types and locahonsin Mono BasIn

Russell (1889) reported thaI compactstony lula (litholdl occurred as a cement inthe gravel of some of the terraces andbeaches around the Jake basin. rangingfrom the present lake level to fannerwater lines. According to Dunn (1953)the greatest quanlity of tula depositsoccurs as a thin crust on the Sierran faultscarp that bounds the west side of thelake. He described it as light gray. tan 10

white. a very porous lithoid variety. andrather typical of lhat found in many partsof the world. Remnants of tula depositscan be seen north of Lee Vining on themountainskle west of Highway 395. ScottStine (California State University.Hayward. oral communication. 1992)reports tufa plasters and crusts at eleva­tions up to 7.070 feet (2.150 m) in MonoBasin. While some of the highest depositsof tufa are about 13.000 years old. luladeposilS older than 40.000 years havebeen found within the Mono Basin (ScottStine. University of California. Hayo.vard.oral communication. 1992).

Thinolitic tufa deposits along an ancientshoreline nearly 6.800 feet (2.075 mJ inelevation and over 400 feet (120 mJ abovethe presenl shoreline are relics of some oflhe highest-elevation tufa lowers. formedabout 13.000 years ago. They can befound just south of State Highway 167.about 1.3 miles (2 km) easl of its junctionwith Highway 395 and just inside theMono Basin National Forest Scenic Areabounda",.

The more spectacular tufa formationsdescribed by various sources as lowers.crags, knobby spires. castle-like structures.pillared ruins. and toadstool-like massesoccur at Mono Lake (Photos 4.5. and 6J.Too.rers may have single or multipletrunks. and range in height from a fewInches to about 30 feel (9 mI. They tendof be clustered in "groves. M most notablyalong the northwest. western, and south·em shores of the lake (F'lgure 6). Towersalso protrude from the surface of lhe lakein these areas. The groves tend 10 bewhere water news underground aJongfaults. or at the sides of ~deltas" within thelake where tributary slreams provide

PhOIO 4. Exposed tuta forma\lOns at shoreline and in lake at South Tufa Area. Mono lake Tufa State Reserve.

CALIFORNIA GEOlOGY JULY/AUGUST 1992 "5

Figure 5. locatIOn map 01 Mono Lake.

Rucluating water levels at Mono Lakehave been found to affect the fonnationand shape of tufa in several WClys. Russell(1889) noted that partially submergedtufa columns and towers would havecirOJlar contractions. or reduced diam­ete~ where the water's surface \evel wasin contact with the tufa. He speculatedthat this was caused by the dash ofwaves, or by solution of the tufa's calciumcarbonate by lake water. In some mush­room-shaped towers. spring water contin­ued to now from the top and dovm theflanks of a partially exposed fOnTlation.Upon contact with the lake surface. cal­cium carbonate preCipitated 10 form flat­bortomed shelves on the sides of theformation.

Sand Tuta

Sand tufas occur primarily along thesouthern and southeastern shores ofthe lake. but have also been found inMill Creek stream cuts above the nonh·\.Ve5I: shore of the lake (Hgure 7). Theyrange in height from a few inches to6 leet (2 m). The sand tula figures consistof tubes. columns. and associated struc­tures of calcite-impregnated pumice s,mel,formed in beach and lake-bollom sedi­ments near the shore of the lake. Thecarbonate-eemented sand is exposedby a drop in lake level and <;ubsequenlv.ind erosion of loose sand around theformation. Cloud and Lajoie (1980) statethat the younger sand structures mayhave formed \lIith'n the past centu~.Sand tufas are found between elevationsof 6.374 feet (1.944 m) and about

A drop in lake level can alter the !lowrate as well as the location from whichspring water flows from a formation.TCM'ers near the shoreline can be foundwith spring water bubbling from the baseof the formation. At the South Tufa Area.what appear to be ~oily upwellings"(Mono Lake Committee. 1980) just off­shore are the locations of fresh walerrising through brine from lakebed springs.Tufa tOVJers that become completelyexposed eventually cease to "grow."Some exposed shoreline to.......ers havetoppled due to lIuct\..1l1ting Joke levcls thillW'ldermine the lonnations. or waves thaterode their bases. Scuba divers who haveexplored submerged tufa grO'JeS reportthe existence of many fragile tufa col­umns and formations whose weight couldnot be supportoo on land.

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Schon and Taft (I 964) confinned thepresence of tufa with summit springs. butmore canmonly fourd spring water seep­ing from cracks in the sides of formations.or from the bases of exposed fom'll\tions_Uthoid towers near the shoreline andthose in the lake sometimes have arcularopenings in their summits from whichspring water has f10IAIed or COI'1timJeS toflow (Scholl and Taft, 1964), Today, thesespringwater features are associated morewith the tufa of Black Point and the northshore than with that of other areas.

Bfldgeport

points of discharge for the springs thatbuilt them." Russell (1889) furtherdescribed one that COI'1tanlOO water of"exceptional purity," saying, "This springfills a bowl three or four feet in diameter.in the top of a tufa dome which risesabout three feet above the lake surfaceand overflows. fountain-like, into the sur­rounding alkaline waters. The interior ofthe basin, and portions of its exterior.are coated with white. calcareous tufa.which is still being prropitated from theoutflowing waters.· Russell (1889) alsotalked of canoeing over the tops of sub­merged towers that \.YBre releasing springwater into the lake in f\ouIs that were~sufficiently strong to denect a 00a1 whenaUov.oed to float over them. ~

-"

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When Russell visited the area in 1883.he explored the lake by canoe. anddescribed tufa lowers and 00mes in theBlack Point area near the northwest shoreof the lake: "They rise in water that is tenor tvJelve feel deep. to a height of abouttwelve feel above Ihe lake surface.... TheIOP5 of sever,,] are hollowed out so as toform basins. and in a few instances thesedepressions are filled with clear. freshwater that rises through the porous andtubular tufa composing the submergedshaft of the structure. These are typicalspecimens of sublacustral spring deposits.which have been left partially exposed bya recession of the lake waters. but are still

TIle 10VJerS in the lake and near thepresent sllore~ne tend to be of the lithoidIIllriety of tufa. Dendritic and thlnoliticrufa can be found in older tOVJers athigher elevations. and in some cases. allthree varieties may occur in the sameformallon.

sources of fresh waler to feed and chargelake-bottom springs. Two of the largestgroves occur along the southern shore01 the lake-South Tufa Grove and LeeVining Grove. Exposed towers in theSouth Tufa Area are estimated to be200 to 900 years old.

'06 CALIFORNIA GEOLOGY JULY AUGUST 1992

6.432 f~t (1.962 mI. They can beobserved at Navy Beach near the SouthTufa Area. Be<:ause of their fragile struc­ture. they are probably more susceptibleto erosion and toppling from rising lake\evels and wave action than are the lithoidtufa formations.

Biological Influences onTufa Formation

18703 fuave lJ.Iren found In the CedarHill area northeast of the lake where itis believed that tufa extracted from olderlakeshore terraces may have been cal·cined to form lime (Mono Lake Commit­tee, 1980). Individuals have collected tufachlUlks for sot.JVenirs and for ornamentaluse in garden:.. WI coIlectlon for anypurpose is now prohibited.

lhe Mono Lake Tufa State Reserveencompasses slate-owned Iakebedlands below the elevation of 6.417 feel0.957 m)-thc lake's surface eleva.tion in1941. This includes about 17.000 acres(6.900 hectares) that have been exposedsince thai year by the diversion of freshwater from tributary streams by the LosAngeles Department of Water and Power.

The remains of fiJamentoul; andI;pherical algal eels occur in lithoid tufaof dry towers at Mono Lake. Scholl andTaft (964) have reported calcareousmat-fonning algae on the surface of.anci partially embedded in. lithoid tufathat is beneath spring water cascadingfrom the summits of pinnacle.. above thelake surface. lhey also determined thatthe algal mat is calcareous due to anabundance of microcrystalline calcitedCcompanied by calcite pellelS. immeshedin the filamentous algae. The mat-form­ing algae in Mono Lake are primarilyfilamentoul; green algae, diatoms, andblue-green algae. Scholl and Taft (1964)believed that due to the dose associationof algae and freshly-deposited tufa. pre­dpltatloo ollilhold tufa could be botani­cally inclJCed. Precipilation result!; fromthe photosynthetic withdrawal of carbondioxide. which lowers the SOlubility ofcalcium carbonate near the algae.

Divers in Mono Lake have found thaIunderw(lter lufa formatlonl; prOVIde rockysubstrates for the attachment of organ­isms such as blue-green algae. and foralkali fly larvae and pupae that have 1;1"2'cialized lime gland tubules capable ofprecipitating carbonate/bicarbonate withcalcium (Herbst and Bradley. i 989).While chemical preopitatlon couJd theo­retically occur at depth in Mono's waterl;under the right conditions. the biologicalinnuences of algae. or insects. VJOUld have10 take place within a photic zone ofprobably no more than about 30 feet(9 ml below the lake surface. The com­plexity of tufa formaliOn continues to beinvestigated. but research at Mono Lakeindicales that biological processes influ­ence at least the IT'lOfl)hology of SOllW

types of tufa formations.

Historic Tufa Uses and CurrentTufa Area Managoment

Histo~lly. the extraction of MonoBa§in tufa for human use has been verylimited. Stone lime kiln:. thol dale 10 the PholO 5. lithOid tuta lOwer a1 Soulh Tuta Area, Mono Lake Tufa Stale Reserve.

CALIFORNIA GEOLOGY JULY/AUGUST 1992 '"

Photo 6 Tula fQfmations at South Tufa Area, Mono Lake Tula SlateReserve. Mushroom-shaped lura (cemer) rormed by spring ...aler thatcontinued 10 flow from the exposed summit and down the sides of theformation to interact with lake waler and fQfm the tlat-bonomed"shell" allake surlace.

Neglt Island

Boundary 01- ScenIC Area

o 2 3 ......

1 "I" "o , ~ :i • 5...--

•

L,A.KE

Paoha Island _~. I..... i'.r ••

•.-Figure 6. Locations andelevations (in teet) ofbases 01 lithoid tutatowers. Elevations areestimated by observa­l,ons and have not beensurveyed. COUr1BsyofN. Upham. U.S. FOfesrSeMce.

TIle Mono Basin National ForestScenic Area. encompassing 116.000acres (116.800 hectares) was designatedby Congress in 1984 to protect the natu­ral. cultural. and scenic resources of theMono Basin. The U.S. Forest Serviceoperates the recently opened MonoBasin Scenic Area Visitor Center 1/4mile (400 m) north of Lee Vining on theeast side of Highway 395. The centerhas exhibits about the Mono Basin. andpersonnel can provide information ontufa groves. nature programs. and lOUTS.

11le reserve. established in 1982. 6managed by the California Departmentof Parks and Recreation (CDPR) to pre­serve the rofa formations and other natu­ral shoreline features of Mono Lake

'" CALIFORNIA GEOLOGY JULY/AUGUST 1992

The Mono Lake Committee operates theMono Lake Visitor Center in Lee Viningwhich has exhibits and information aboutthe tv\ono Lake and Basin area.

Figure 7.localions and elevalions of bases of sand lufa, Elevations are estimated byobservations and have not been surveyed Courtesy of N. Upham, U.S. Forest Service.

Ted Rieger is a freelance writerand photographer in Sacramento.Galfomaa. He specializes in naturalhistory, geology. and historical sub­jects. and proouces technical andbusiness articles for tr&de publica­tions. Ted has varied experience inoutdoor recreation and resourcemanagement with federal and Staleagencies.

Observing Tufa at Mono Lake

The South Tufa Area. managed byCDPR. is one of the most easily acces­sible locations for tufa obselVation It isreached by a ooe-mile dirt road that tumsnorth from Highway 120, about 5 mileseast of the Highway 395 junction south ofLee Vining. 1llere Is a self-guided trailthrough the tufa (otmations. and CDPRregularly condlKts naturalist-led tours. AtMono Lake County Park. about" milesnorth of Lee Vining on the east sk:le ofHighlM':ly 395. there is a boardwalk trailthr~ the tufa grove.

o 2 3 milesI 'I II II

o 1 2 3 4 5 kllom\llers

Boundary ofScenic Area

t---I Aaogll or sand and lula rormaHon

Paoha Istand

Negit Island

LA~E

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~

Lee Vining.

REFERENCES

Blackwelder, Eliot. 1954, Pleistocene lakesanet drainage In Ihe Mojave region. south­ern California: California Division of MinesBullellfl 170, p. 35·40.

Blanc. R.P., and Cleveland. G.B.. 1961.Pleistocene Lakes of southeastern Califor·nia-I: Minerallnformallon ServiCe, April1961. p. 1-7.

Bureau 01 land Management. Recroationlal'lds of the California desert. 1972,p.6,7.

Calilomia Department 01 Parks & Recreation.1986, Mono Lake Tufa State Reserve andMono Basin National Forest scenic Area,lolel-out brochure with map and draWings.

Cloud, Preston, and lajoie, K.R .• 1980. Cal­cite-Impregnated deltu!dlzallon Structuresin ~noral sands of Mono Lake, California:Science, v. 210, p.1oo9·1012.

Dunn, J.R.. 1953, The onon of the dePOSItsof lufa at Mono lake: Journal of Sedi­mentary Petrology, v. 23, p. 18-23.

Hems!. D.B., and Bradley, T.J.. 1989, Amalpighian tubule limo gland In nn insectinhabiting alkaline salt lakes: Journal ofExperimental Biology, v. 145. p. 63-7B.

Mono Basin Ecosystem Study Comminee.1987, The Mono Basin ecosystem.efle<:ls of changing lake level: NallenalAcademy Press. Washington. D.C,272p.

Mono Lake Commltlee. 1980. Mono lakeguidebook: Kutsavi Books, Lee Vining,CalifornIa, 114 p.

Pulnam. W.C., t971. Geology: SecondEdit.:;!n, Oxlord UfUversity Press. NewYOrl\, p. 145.

RU5",II.I.C., 1883. SketCh of the geologICalhistory of Lake Lahontan: U.S. GeologicalSurvey Third Annual Ae~rt. p.189·235.

Aussell. I.C.. 1889. Quaternary hIstory ofMono Valley, camornia: U.S. GeologicalSurvey Eighth Annual Report, p. 261-394.

Scholl. OW., 1960, Pleistocene alga! pm·nacles al searles Lake, California: Journalof sedimentary Petrology. v. 30. no 3,p.414-431.

SCholl, OW., and Tah, W.H.. 1964. Algae,contrbJlors to !he 10rmatlOn of calcareoustufa. Mono Lake, Califorma: Journal 01Sedimentary Petrology. v 34. no. 2,p.309-319.v

CALIFORNIA GEOLOGY JULYlAUOUST 1992 ",

Geometry of Normal Faulting in TecopaValley, California from Magnetic Surveys

MICHAEL R. GROSS, Pennsylvania Slate UniversityJOHN N. LOUIE, University of Nevada, Reno

Photo 1. Normallaults exposed in a roadctJt on Route 178. 3.7 mWes east (6 0 km) of Shoshone (Heydari, 1986). View tS to thenortheast. These west'tlipping laults ollset tuffaceous rocks of the Chicago Valley Formation. Allirs! glance Ihe main fault In thecenter of the photograph appears 10 be a reverse fault However, the yellow and orange luffs truncated by Ina fault are not the samestratigraphIC horizon. Phato by David L. Wagner.

INTRODUCTION

I ate Cenozoic tectonism in theL Basin and Range Province isdominated by east-west crustal extension.VJhk:h Is reflected in a 5eries of north­south trending horsts and grabens andabundant normal and strike-slip faults.Estimates for the amount of crustalextension vary from 20 percent (Stewart.1971) 10 100 percent (Wernicke andothers. 1988). Several me::hanisms havebeen prop::>:>etlto lICCOWlt for the largeramounts of extension. incb:ling listricnonnal faults (curved. dov.Tlward-flalleningfaults) (Wright and Troxel. 1973) arK! ashallow. gently--dipping regional detach-

menl extending from Pahrump Valleywest to the Sierra Nevada (Wemicke andothers. 1988). Ellis and others (1989)suggest thai lateral displacement alongintersecting. complementary strike-slipf<:lulls may account for a large portion ofthe net extension.

Magnetic SUl'\leys· can klentify sub­surface structures related to normal fault·fig in areas VJhere volcanic rocks withhigh magnetic susceptibilities are).lxtapos.ed wilh Iow-<.usceplibiKty sedi­mentary rocks. TOC(lp<! Valley provKles anexcellent locality for such a stldy since it

• T"rms mboldface lypt ~" ""lllIlined 011 pq 116

contains faulted Tertiary rhyolites andbasalts as well as abundant evidence forexle/l51onol leclonlsm. E\idencc for nor·mal faulting includes lhe prominent range­front fault at the base of the RestingSpri~ Range. numerous normal faults ina roadcul on Roule 178 in the samerange (Heydari. 1986) (Photo 1). an offsetIAlCkled luff marker horizon in the TertiaryrhyoNte. l.Ind rotated fauh blocks exposedIn Tecopa Valley (FJgure 1). The purposeof this study was to condJcl a series ofground-based magnetic surveys perpen­dieu1ar to regional strike in order tounderstand the geometry of normal fault­ing in Tecopa Valley.

,w CALIFORNIA GEOLOGY JULYIAUOUST 1002

GEOlOGIC SETIING

Tecopa VaBey is il easlern California.approximately 20 rri1es 130 km) east

of Death Valley in the Basin and RangeProvInce (Pl9l'C II. The north 50Uthtrending valey. couering an area of ap­proximateiy 200 5ll-Bre miles (500 kIn./),is IlankOO 10 the ea5t by lhe RestingSpring Range and to the west by the[)U:)Iin Hills. both composed of Precam­brian 000 Combrian 5edimenkary ruclu

(Nilsen aTl:! Chapman. 1971. JenningS.1977). Tertiary rhyolites at least 787 feet(240 m) llUck areex~ Bl Re:itIngSpring Pass (Heydari. 1986). Tertiarybasalt crops out as rotated faub bkx:ksnear Sho~;hone and possIt*) as fauJt~

related intrusions at the base of the Rest­ing Spring Range. The center of TeoopaValey is fkt WIth ftatlytng. rela~Wldefonned. late Pliocene and earlyP'leistocene l..:lke Tecopa sediments(Photo 2). The sedmems are at least

235 feet (72 m) thkk and consist ofmudstones interbedded \Io-ith layers ofvolcamc ash (Sheppard and Gude. 1968:HiUhouse. 1987).

A prOlTlUleJ\t normal fault at the IIIE!SI'

em base of the Resting Spring Range ismarked by a series of \Io-'eS!'<i1pping Rat­irons composed of fauh-gouge material(Photo 3L Exposed within the vaDey areeast-dippmg. nonnal-fault bb::ks of QitherPrecambriano Cambrian sedimentaryrocks or Tertiary 1.OIcanics (Figure 2.Photo 4)

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FIQUr8 1, loca:x>n map 01 Tecopa Valley ShowIng \ \plo;ectlOl, Wles ot magnetIC surveys Bedrock blocksare Tr _ Tertiary rhyolite; BKO _ Bonanza KIng Oolomrte:\Tb _ Tertiary basah: p£-£ _ Precambnan·cambnan \sedImenlary rocks Small numbers _th arrows rcprc:senl \locatIOn and VIeW directJon 01 Photos 2·4 Modified from \Hillhouse ('981). \

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CALIFORNIA GEa.OOY JlJI..YIAUGUST 1992

Photo 2. Tecopa Lake beds near Route 178. The flaHying mudstones indicate thai major extensional teclonism stopped before thedepoSition of lake sediments al approximately 3 Ma. Photo by MIChael Gross.

Photo 3. View of the Resllng Spring Range looking southeasllrom the center of Tecopa Valley. The Precambrian·Cambrian sedimentaryrocks 01 the Resting Spring Range dip to the east In the baCkground. The west·dipping llatirons at the base of the Resting Spring Range areexposures 01 resistant rault-gouge matenal or the range·lront lault. Photo by John Louie.

'" CALIFORNIA GEOlOGY JUlY/AUGUST 1992

DUBLIN HIllS- RESTING SPRINGRANGE Figure 2. Genera6zed schematIC cross

sec!Jon through northern Tecopa Valley.Lithologic Ul'lll$ are: Preeambnan-Cambnansedimenlary rocks (p£-£): TertJafy ChinaRanch eqUIValents (Tcr 1): T81tJaJy voIcarncs(Tv): PIiocene-PlelstlXel'le Lake TeropasedllTlentS (Ott); and Quaternary allMumlOa).

Photo 4. Titled Tertiary rhyolite block north 01 Route 178 (Figure 1). Photo by MdIaeI Gross.

CAllFORNIA GEOlOGV JUlV AUGUST 1992 '"

METHODS

T\\10 magnetic surveys were conductedin Tecopa Valley (rlgure I). Data v..oerecollected along a northem line from mid­valley eastward across Route 178 towardthe base of the Resting Spring Range.past a block of Tertiary rhyolite (rlgure 1.Photo 4). Data v..oere collected along asouthern line eastward along Old SpanishTrail Highway between Route 127 and thetOVJn of Tecopa.

An EG&G mcx:lel G-856 proton pre­cession magnetometer measured total­iiekl values al 54 stations spaced 165 feet(50 m) apart in the northem profile and at20 stations with 655-foot (2DO-m) spacingin the southern profile. At least two read­ings were taken at each station to assurerepeatability. and diurnal variationswere measured at one station at least onceevery 2 hours throughout each day.

Diurnal variation is a large source oferror in a magnetic survey. Corrections inthis survey were accomplished throughlinear interpolation between repeat stationdata points and normalization of repeatstation measurements to a consistent value(PIgure 3).

Sunspot-induced magnetic stonns.another large source of error. occurredduring the survey. We received measuredstonn intensity values for our surveydates of February 25 and 27. and March1. 1990 from the Fredericksburg.Virginia Geomagnetic Center {B. Odell.personal communication. 1990}. Stormactivity for these dates ranged from30 nanoteslas {nn to 40 nT. intro­ducing a fundamental uncertainty in theprofiles of rlgures 4 and 5. While theactivity is larger than the diurnal varia­tions. fortunately it is significantly smallerthan the variations caused by basinstructure.

We used a computer-based softwarepackage to calculate theoretical mag­netic field intensity values matchingmajor features of the observed profiles.rlgures 4 and 5 show susceptibihty con­trast models and their correspondingmagnetic intensity profiles. The Tertiaryrhyolites and basalts are assigned mag­netic susceptibility values (in cgs units)of 0.00068 and 0.004. respectively.whereas the sedimentary rocks and basinfill are assigned susceptibilities of zero.

AESUlTS AND DISCUSSION

rlgures 4 and 5 present the resultsfrom the two magnetic surveys. The topportion of each figure shoYJs magneticfield measurements (squares) along withthe theoretical values computed fromsusceptibility models (fl11ed circles). Thelower ponion of each figure is a sche­matic geologic cross section representingthe model.

Northern Prolile

The northern profile (rlgure 4) "lx!ginsat 3.5 km along the line of projection andinitially sllovJs a decrease in magnetic fieldvalues progressing northeast. At approxi­mately 4.5 km there is a sharp positiveanomaly which then decreases tOVJard theend of the profile. The lOOO-nT magni­tude of the anomaly measured by closely­spaced ground-based magnetic surveys ismuch larger than the lOO-nT variationover the length of Tecopa Valley deter­mined Irom aeromagnetic surveys (Blakeand others. 1977). It is also considerablylarger than the 40 nT of error introducedby magnetic stonn activity. Both the mag­nitude and location of the anomaly sug­gest that the profile crosses a ma;or struc­tural boundary between Iow-susceptibilitysediment in the center of Tecopa Valleyand high-susceptibility bedrock along theeastem skle of the valley.

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A line statton measurement was taken at17.163 hours. The ver1lcal orange line drawnat 17.16 intersects the curve at 50,443 nT.ThIS dilfers trom the !irst repeat stationmeasurement by 6 1'1T. To correct lor diu,"alvarialion, 6 nT was subtracted trom the linestation value to give 50.486 nT.

Figure 3. Plot of diurnal variation in the tota)magnetIC field measured a\ \ne 'e?e81 slalionf()( the northern line on February 25, 1990.The IIrst measurement at the repeat stalJon.50,437 nT. was taken at 12.692 hours. Thisgraph shows the curve drawn through all themeasurements taken at the repeat stationthroughout the day. Measurements lakenalong the line were corrected lor diurnalvariation as in the following example.

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CALIFORNIA GEOLOGY

" "

JULY AUGUST 1992

line stationmeasurement

tirst repealstationmeasurement

50.492 nT 17.163 hours

50,437 nT 12.692 hours

0.0 1.0 2.0 3.0 4.0 5.0 6.0

fOEo 51400>-t: Field Measurements ---..00zw>- 51000~Q

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SW DISTANCE (km) NE

FlQure 4. Magnellc field data. model results, and schematic geologic cross section 'or the IlOrthern profile.j) _ denSity, t • magnetic susceptibility In cgs Uf'lIls.

Southern Profile

The large magnelk anomaly \NeSt 01the tilled block of rhyolite north of Route17 (Photo 4) appc.::r.rs to represent sub­surface continuation of the range-frontfault. 1lle model which best cCITespondsto the obscTWd magnelk liek:l wI", is anonnal fault dipping 45 degrees to theVJCSt. VJith highly susceptible volcanics inthe footwall to the ea~ (RgllTe 4).

We assigned a susceptibility (k) valueof 0 00068 ond d Ihkkness of 2.000 feet(600 m) to the rhyolitic material in thefootwall, The magnilude of the anomalySugge.1S there IS a very highly susceptible(k - 0.004) block 1.800 feet (550 m)wide along the fault. This might representa layer of basalt intruded along the laultzone. There are outcrops of basalt associ­ated with the range-Iront fault exposedalong the western flank of the RestingSpring Range that would further supportthis mOOel. A problem VJith the magnetk

model is thilt it requires a rh~1ite thick­ness of about 2.000 feet (600 m) whkhIs not entirely compatible with field evi­dence. Ht¥lari (1986) measured a thick­ness of only 787 feet (240 m) for theResting Spnng Pass Tuff.

Gravity surveys along the northernprofile in Tecopa Valley suggest a modelof low density sediments in the basin andhigh density bedrock along the easternand western flanks (Gross and others.1990). The result of gravity modeling isshown in coojunction with the magneticmcdel in Figure 4 ar'Kl depicts the range­front fault as a west-dipping structureVJith dense bedrock 00 the east and~dense basin fill on the west. Both themagnetk aT'd gravity data place therange-front fault at approximately thesame 10catkn along the profile. thoughthe gravity model infers a shallovJer dip of18 degrees.

Magnetic field measurements aloN::! thesouthern profile exhibit two peaks. one atapproximately 0.5 km and the other at3.4 krn (Figure 5). The maximum at 3.4km is located along the strike of TecopaPeak (FJgIJe I). The range in values isless than 100 nT. which is much smallerthan the anomaly observed along thenorthern profile. Magnetic storm activitymeasured 30 nT. A model thilt corre·sponds to the dala consists of a pairof buried east-rlipping slabs wilh mag·netic susceptibilities of 0.00068. The<;Ial,<; are 425 fOOl (130 m) thick and dip23 degrees to the east. with the westernslab at a depth of 145 feet (l05 m) andthe ~S1cm slab l!ilt Ddepth 01 510 feet(ISS m). These slabs may be Tertiaryvaeanics I.l.hlch have been rotaled alongwest-dipping normal fo'luhs. TIlls struclUreis consistent with all of the bedrock expo­sures in Tecopa Valley. as well as the dipof the Resling Sprh"Vil Pass Tuff (Hey:lari.1986). Also. it implies an irregular surfacealong the bedrock!basin·fill contact.

CALIFORNIA GEQ.OGY JULY/AUGUST 1992 '"

0.0 1.0 20 3.0 '0 5.0 60

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~ •506'0 'I>.. model results. and schematICZ 0 0 / . geologlc cross sec:tJon lor !hew "---- southern profile. Data from~ 0; 50620

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Diurnal variatklns, the f1'lCft or lessdaily cycle 01 changes 10 the magnetic lieid.musI be measured dumg a 5UM!Y to comdlor the el<:IetTIilII fietI Also,.". magnebCstonns (vdem and rapid changes in m<qJeOC

intertSlly) 0CClImflg Wring the survey musI berecorded, 1M is~ by tailing amagnetometer rudi1g at one location. atinlervab during the day 01 the survey. The\II1riation in the measurements ref.ects mag­netic changes m the ltXlemallWd thai: day.5tn'w!, measuremeru can be corteetedahor tt- CM'"'!JP'l /Ire plotted on. a graph(F\guR 3)

digllaIIy. on gMYfIa5 h general. me moremagnetJc fTllnl!f'I1is~. the larger theffia!J'l!tiIC anomaly.

Glossary

flatiron: 1he CJOS5 sectDn of a lnangJlar Magnetic surve,.'S Iocdte rTliII9f'dicridge of SleePY Incbned teSISWll rocks 00 anomalies. IrTeguIanlle5 in the distnWKlO 01the flank 01 a mcullam magnellm:l malerial n lhe crust of the e<tM

Magne.dc suscepllbllity is a measure of theease of magnelization. Most sedimenlaryrocks are less ITWlgnetic than igneous rocksand therefore have rElatively low suscepllbUi'ties. Magnellc surveys are olten used to define11 faull by measuring the difference In mag­netic fields on either.side of the fault Thef/lult may also be defned by low mllgnetiCreadll'lgS caused by lhe leaching of magnelic:minerals 10 the fract\red rock. or by highmagnetIC readings caused by lnuwon. 01Igoeo,,< matPriai aloog a fault in a sedimentary

""'"

gravity SUrvi!y. Measurements of thegravilational held at different locationsVarialions dellOIe dLfferenccs in rock type.

The earth's tmgnctk field consists ofthree partS If the internal. or secular, fieldwhich varies 0VflI'~ or unluries andis allributable 10 lhe basic properties of theearth; 2) the external field. which variesrapkly and Is due 10 SOI.A'aS above the sw"'

face; and 3) the nearly constant anomalyfield, ....t-uch Is cau5ed by~WIth,n thoanear-suface CN5t of the urth. such as mag­rwtJc: rTIirIerah, The~ fietI is~in dAla pnxessang by remow'IQ the other

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is a highly sensruw. acante. portab6einstruTtent that rnea:sura ~netlc:-fIekl

intlMS;ty, the foIa exerted by a magneucroett on II~~,~ic fieldonlertSlly is expressed In \nl:ematlOn& sysIem(SI) lRts as eIas and in anhmeler-gram­second system (egs) uruu as gaus5 or gam­mas (10' gauss.), A RilnOtesla Inn is tD'testa, ,md 15 equlvMlllt to 0 9l'ml1'lllo, 'l"hemagnetomeleJ' displays the measuremenl

ACKNOYIlEDGMENT$

We are grateful to R Laird. S. NIchols.D. Verdonck. N. Yonkers. am J Zhangfor their assistance in the field. We wouldalso like 10 thank L Wright for his ....w­able discussk:Ins on Tecopa Valley geol­ogy_This research was supported b; thePenns:ykJania Stale UnioJersity Departmentof Geosciences arK! generous donationsfrom Che\.ron USA. Ire.. Mobil Corpora­tion. and British Petroleum Corporation.

CONctUSK>NS

Magnetic: surveys have identified strue­lUres in the subsurface olTecopa Valleyrelated 10 e.,1ensiona! tectonism "Therange-front fauh ak:lng the western I1iInkof the Resting Spring Range can be OCC\J+

rately mapped by virtue of its strongmagnetic signal in areas where it is notcxposod. 1hit magnetic dala and modelssuggest the presence of a basaltic in:ru­sion on the order of 1,000 feel (300 mlthick along the range-front fault. In addi­lion, a series 01 east.<Jipping fault blockswere identified In the Slbsurface alonga profile in southern Tecopa Valley.which is consistent with the overall geom­etJy of fault blocks exposed in the valley.Ongoulg research by groups from PennState and Nevada-Reno wiD improve our..........."" 01 the .u.uria<e geologyin Tecopa Valley.

'" CALIFORNIA GEOlOGV JULVAUGlIST 1992

Michael Gross will receive hisPh.D. in structural geology in thefall of 1992 from Penn State Uni­versity. His research focuses on theanalysis of fractures and faults insedimentary rocks, and relatingthese features to the slate of stressin the earth's crust. Michael hasbeen involved in detailed field stud­ies in the Appalachian Plateau ofVJeStern New York and SO\.lthernOntario. the Transverse Ranges ofCalifornia. and the Salt Ranges ofPakistan.

John Louie is an associate pro­fessor at the Seismological Labora­tory at the University of Nevada'sMackay School of Mines in Reno.His research interests involve imag­ing the structure of major faults inCalifornia such as the San Andreasand Garlock. John leads an annualfield trip to Death Valley to conductgeophysical surveys.

~PECIAL ~llON 11~

RElJ) GUIDE TO THE GEOLOGYAND METAMORPHISM OF THEFRANCISCAN COMPLEX AND WEST­ERN METAMORPHIC BELT OFNORTHERN CAUFORNIA. SPECIALPUBUCATION 114. Peter Schiffmanand David L. Wagner. editors. 1992.$10.00.

Spedal Publication 114 contains fivechapters that discuss metamorphism andt~tonics affecting Mesozoic and Paleo­zoic rocks in the Coast Ranges and SierraNevada provinces of northern California.The publication was prepared for an inter­national symposium, The Transition fromBasalt to Metabasalt: Environments, Pro-

REFERENCES

Blake, M.C. Jr.. Zielz. I.. and Daniels, D.l.,1977. Aeromagnetic and generalizedgeologic map of parts of central Califor·nla: U.S. Geological Survey GeophysicalInvestigations Map GP-91B. scale1:1.000,000.

Ellis. M.A.. Zhang. p .. and Slemmons, D.B..1989. Active tectonics of the southernPanamint Valley: Implications for theproposed low·angle fault under northernPanamint Valley [abstract]: EOS, Trans­actions of the American GeophysicalUnkln. v. 70, p. 465.

Gross, M.A.. Louie. J.. Laird. R.. Nichols, S.,Verdonck. 0 .. Yonkers, N., and Zhang, J..1990, Geometry of normal faulting inTecopa Valley. California, from small­scale geophySical surveys [abstracl):EOS. Transactions of the American Geo­physical Union. v. 71. p. 1585.

Heydari. E.. 1986, Geology of the RestingSpring Pass Tuff: CALIFORNIA GEOL­OGY. v. 39, p. 253-261.

Hillhouse, J.w., t987. Late Tertiary andQuaternary geology of the Tecopa BaSin.soUlheastern California: text accompany­ing U.S. Geological Survey MiscellaneousInvestigations series Map 1-1728. scale1:48.000. 16 p.

cess. and Petrogenesis, hek! at the Uni·versity of California. Davis.

Four of the chapters are guides forliek! trips hek! in conjunction wilh thesymposium. Chapter 1 is a guide for atrip in the San Francisco Bay area wheremetabasa1fs of the Franciscan Complexare exposed. Chapter 2 is an overview ofthe western Metamorphic Belt of theSierra Nevada. Chapters 3, 4, and 5 areguides for field trips in the northern partof the Wesfern Metamorphic Belt. Thesetrips are in an area covered by the soonto be released I :250.000 scale GeologicMap of the Chico Quadrangle, California.This map will be the latest of the Divisionof Mines and Geology Regional GeologicMap Series. (RGM 007A).

SPECIAL PUBUCATION 114 is avail­able for reference and purchase at all

Jennings. CW.. 1977. Geologic map ofCalifornia: Calilornia Division of Minesand Geology, California Geologic DataSeries Map No.2. scale 1:750,000.

Nilsen. T.H.. and Chapman. R.H .. 1971.Trona sheel, Bouguer gravity map ofCalifornia: California Division of Minesand Geology, scale 1:250,000.

Sheppard. A.A.. and Gude, A.J.. III, 1968.Distribution and genesis of authigenicsilicate minerals in tuHs of PleistoceneLake Tecopa, lnyo County. California:U.S. Geological Survey ProfessionalPaper 597. 38 p.

Stewart, J.H., 1971. Basin and Range struc­ture: a syslem 01 horsts and grabensproduced by deep·sealed extension:Geological Society of America Bulletin.v. 82. p. 1019-1044.

Wernicke. B., Axen. G.J., and Snow, J.K.,1988, Basin and Range extensionalt~lonlcs at lhe latitude of Las Vegas,Nevada: Geological Society of AmericaBullelin. v. 100. p. 1738-1757.

Wright. L.A.. and Troxel. B.W.. 1973. Shal·low-lault interpretation 01 Basin andRange structure. southwestern GreatBasin: in De Jong. KA. and SCholten. R..editors, Gravity and Tectonics: John Wiley& Sons. Inc., New Yorf<.S

three DMG offices. In addition. the Sacra­mento office offers prepaid mail ordersales.

SACRAMENTO GEOLOGIC INFORMATIONAND PUBLICATIONS OFFICE

801 K Street. MS 14-33Sacramento, CA 95814·3532

(916)445'5716

SAN FRANCISCO BAY AREAREGIONAL OFFICE

1145 Marf<.et Street, 3rd FloorSan Francisco, CA 94103

(415)557-1500

LOS ANGELESREGiONAL OFFICE

107 South Broadway, Room 1065Los Angeles. CA 90012·4402

(213)620-3560

CALIFORNIA GEOLOOY JULYtAUGUST 1992

APRIL 22 JOSHUA TREE, and JUNE 28 lANDERSand BIG BEAR EARTHQUAKES, 1992

TOUSSON R. TOPPOZADA, SeismologistRICK I. WILSON, Engineering Geologist

Earthquake Date Time (PDT) Long oW Depth (km) Mag

Joshua Tree

Landers

Big Bear

April 22, 1992

June 26, 1992

June 28, 1992

21 :50

04:57

08:05

33.95

34.20

34.20

116.32

116.44

116.83

12

9

10

JOSHUA TAEE EARTHQUAKE

The Joshua Tree earthquake occur­red at a depth of 7 miles (12 krn) on asubsurface north-trending, right-lateral.Sirike-slip fault (California Institute ofTechnology lern and U.S. GeologicalSurvey [USGS!. written communication).No surface faulling was observed. butaftershocks extended northward 10 nearLanders. This event is now consideredto be the start of a ma)oT earthquakesequence that peaked with the twoJIJI"le 28 events (see map).

LANDERS AND BIG BEAREARTHQUAKES

The Landers earthquake occurredalong a near vertical. north-northwesttrending. right-lateral. strike-slip fault.Faulting propagated mostly northwardIrom the epicenter. generating about50 miles (SO km) of surface fault ruptureon four previously mapped faults: theJohnson Valley, Homestead Valley.Emerson. and Camp Rock faults (seemap). These faults had been zoned overmost of their extent by the Division ofMines and Geology's (DMG) Alquist­Priolo program and thus had beenrecognizee! as being capable of innictingdamage by fault rupture. Rupture alsooccurred along minor faults near thetovm of Yucca Valley. and in step'overareas between the zoned faults (se€map).

/' ,I \

1(,,--/ \ .;> ,

--, '.- •..Main trace 01 Johnson Valley faull at the Country Gospel Church in the Flamingo Heights area.Zone ollractuflng Is appro~imatety 30 feet (10 m) wide. More than Gleet (2 m) 01 righllaleraldisplacement was measured at the parkJng spaces (upper left), Phoro by Jack McMillan,

'" CALIFORNIA GEOLOGY JULY,AUGUST 1992

Surface rupture on unnamed faul! in Homestead Valley. Photo by William A. Bryant.

Vertical scarp of the Emerson fault. west side down, near the zone ot maximum laultdisplacement. Although there is a vertical component of displacement along this portion ofthe fault, some of the vertical separation in this photo can be attributed to right-lateraljuxtaposifion 01 a ridge and a swale. Photo by Tim McCrink.

Minor sympathetic movements weretriggered on nearby faults incltxling thePisgah. Calico. and Galway lake faults.Displacements varied greatly along thefault rupture. Apparent vertical displace­ment of up to 4 feet (1.2 m) was observedon the Emerson fault (lOVJer left photo).A maximum right-lateral displacement ofabout 20 feet (6 mI. one of the largestsurface fault displacements observed his--­torically in California, was measured alongthe Emerson fault (photo below), Thisillustrates that some of the right-lateral slipbetween the Pacific and North Americanplates that is not occurring on the SanAndreas fault is occurring on faults in theMojave Desert.

Wide zone of deformation along the Emersonlault in the area of maximum right·lateral off­set (west 0' Galway Lake). Phoro by WilliamA. Bryant.

Historical earthquake activity in thearea incltxles the 1975 M

l5.0 Galway

Lake earthquake (see CAUFORNIAGEOLOGY, October 1975) and the1979 Ml 5.3 Homestead Valley earth­quake (see CAUFORNlA GEOLOGY,March 1980), both of which resulted insurface fault rupture. Faults that rupturedduring the 1975 and 1979 events rup­tured again during the Landers event.

CALIFORNIA GEOLOGY JULY/AUGUST 1992 '"

The maximum Modified Mercalli Intensitywas IX at Landers (Glenn Reagor.National Earthquake Information SelVice.oral communication).

The Big Bear earthquake occurred at adepth of 6 miles (IO km) along a subsur­face northeast trending, left-lateral. strike­slip fault (CIT and USGS. written commu­nication). No surface fault rupture \AlaS

found.

Approximately 500 aftershocks ofM

L3.0 or greater occurred (see map)

(crr and USGS. written communication)during the month following the Landersand Big Bear earthquakes. These includerelated seismicity to the northeast nearthe Pisgah fault and to the northwest nearthe Calico fault.

The earthquakes occurred in sparselypopulated areas so damage and casualtytotals were low. The Landers earthquakecaused major damage to buildings and to

This boulder rolled down the steep south side of Mill Creek Canyon into the back yard 01 ahome in the community of Forest Falls. It is one of the larger boulders set in motion by theMs6.6 Big Bear eanhquake and its aftershocks. Photo by Tim McCrink.

I the lifeline infrastructure in the communi-;

'M~~Oties of Landers and Yucca Valley. Strong

j '1P MAGNITUOES0 ground-shaking. landslides. and rockfalls

c 3.0'" caused by the Big Bear eanhquake dam-0° 0 4.0- l aged buildings and roadways in the Big". -. Bear Lake area. There were 377 minor5.0-

~t 6.0..-and 25 major injuries and one fatalityfrom the June 28 earthquakes.

7.0-... - - ACKNOWLEDGMENTSC

ro," r Bill Bryant and Mike Reichle (DMGl.

'". c

I< fand Egill Hauksson (Cm reviewed the

30' - ~~manuscript. Claudia Hallstrom (DMGI, c assembled the earthquake reports that

•.~ • were used in this article. Katrin Douglass." - from CIT provided the epicenter map.'. C

t20' -C

, l".

1WENTY-NII/£1 ,~,

J~ ~ 8 NTAIN AunEpicenters 01 ML 3.0 and greater eanh·

:f'8£RJJARDINO~

quakes for the month following the June 28.

1 eR£OU/>'l)S1992 Landers and Big Bear earthquakes

0 SAN (CIT and USGS). The epicenter 01 the April

"'1 <,;22. 1992 Joshua Tree eanhquake has been

~, added to the map (southernmost star). Major, >. faults are shown in black, while the June 28,, o.~ 1992 fault rupture is highlighted in orange.J \ .... Emerson and Camp Rock lault rupture de·

I • Itails have been added. Courtesy of CIT and

". ""1" ". ..."

,.. " . II'"USGS.

"0 CALIFORNIA GEOLOGY JULY/AUGUST 1992

Earl Hart Receives 1992Alfred E. Alquist Award

for Achievements inEarthquake Safety

in California

...... WUOM._

DEPARTMENT OF CONSERVATION00 .,.. ...._'..""""" _ Of ..... • ""G'Ol""........- Of OIl ..., cAS

D"...._"" ..c,~ 00' <h-. ... ,-.0,....-. c. KIlO·.."_<t,...",_

(916) J2Z-10aO

J"n~ 9. 1992

II •• Earl W. Hn,tDepart.ent of Conne~at1on

Division of IIinen And GeologylUll M",k.. t St..... t. Third floorSan frnnclnco, CA 94103

Dea' Earl:

congutuletlonn on l><l\n<:l aelectod by the cnlitorni. EarthquakeSnhty I'oundatlon u th...ec1pl.mt of the U!12 Alquht Award forIlchl ......nu in earthquake safety In California.

You hnve been n fine enlOple of the do<I1""t.d, hard-workln'.! civilnarvont we Ilke to a.... In SUte GOvernllent. 'tour t1re1euatrorta are 01"0 01.11 ,.cog"hed throuqhout the geo1oqlcco....unlty nnd by other. Involved in • .,18_le ntoty. With only n..... 11 "tofr. you h~ve prepared ~H special Studie" Zon"" Map" andreviBed 124. In addition, ." Manager or the fault Evaluatlon andZoninq ProqulI Blnc.. Ita inception In 1913, you have providedvaluabla Inro..ation and '1uld"n"e to cltla.. ~nd counti .."throuqhout the Stat...

Again, conqntulatlonB Cor a job w811 don ...

sincerely,

:;f.?. JA:'-'jEdward G. lleidi'lolractor

cc: B. GuerardJ. D<l.vh

. October 24-25

. October 24-25

GEOLOGICAL SOCIETY OF AMERICA OFFERS SHORT COURSESOctober 1992

The Geological Society 0' America (GSA) will offer the 'ollowing courses at its annual meeting in Cincinnati, Ohio in October 1992:

• Geographic Information System Software: Facts and Fdion October 23-25• How to Do Anything with Mohr Circles (Except Fry an Egg):

A Short Course About Tensors for Structural Geologists ..• Introductory Rock and Paleomagnetism ..... ,..... "., ....• EnvironmenlalfEngineering Geology and Land·Use Planning-An Interface

Between Science and RegUlations ,... . October 25• Paleosols for Sedimentologists . ,.... . October 25• Phase 1- Preliminary Site Assessments (PSAs) October 25• Practical Tracing of Ground Water. with Emphasis on Karst Terranes ...October 25• Environmental Applications of Shallow Seismic Reflection .. October 30

For more information. contact: Edna A. Collis. Meetings Coordinator. Geological Society of America, 3300 Penrose Place, Boulder,CO 80301. (303) 447-2020, FAX (303) 447-1133.

CALIFORNIA GEOLOGY JULY/AUGUST 1992 '"

THE MINERAL INDUSTRYOF CAUFORNIA-1991

FRED V. CARRILLO. U.S. Bureau of Mines

Hayden Hill, lassen County. Photo by John Burnett

A ccording to the u.s. Bureau ofl""l Mines. CaJifomia was the nation'slargest producer of nonfueJ minerals in1991, accounting for nearly 10 percentof the tOlal U.S. production. The value ofnonfuel mineral commOOities producedduring the year was estimated at $3.02billion. an increase of more than 8 per­cent from 1990. The State led in theproduction of asbestos. boron minerals.portland cement. diatomite. calcined gyp­sum. construction sand and gravel. rare­earth concentrates. and tungsten.

Industrial mineral production tn pon­land cement. clays. crude gypsum. lime.construction sand and gravel, and crushedstone mirrored the continuing declinein construction activity. Declines areexpected to continue. However. metallicminerals. particularly the precious metals

and molybdenum. as well as asbestos andpumice. were responsible for the increasein estimated value over that of 1990.Increased gold productlon allowed Cali­fomia to retain its rank as the secondlargest gold·producing State.

Employment. The California Depart­ment of Economic Development statesthat the nonluel mining industry em­ployed 9.000 workers in October 1991.unchanged Irom October 1990. Approxi­mately 2.200 workers were employed inmetal mining and 6.800 workers in non­metallic mineral mining.

Exploration. Precious metals wereexplored in several areas throughout theState. despite IovJer silver and gold plices.Exploration was begun at the IcIaho-MaTY"land mine near Grass Valley. Nevada

County. The program included waterremoval. mine rehabilitation. and under­ground exploralion drilling. KennecottCorporation and Canyon Resourcesexplored in the Panamint Range west 01Death Valley. Arizona Star ResourceCorporation drilled its Imperial Countyproject 40 miles (65 km) nonhv.rest ofYuma. Arizona. outlining two gold pros­pects: the Indian Rose deposit and theOcotillo de~it. Tenneco Minerals drilleda U.S. Forest area near Antelope Valley.

Legislation. A new California lawdictates the elimination of plastlc or PVCpipe for mining claim markers. Onlywood. stone, or salld metal markers cannow be used to mark claims on federallands in the State. The law also reduces tofive the markers required for outlining aclaim. Another law clarified the type ofmining wastes lhat are exempt from haz­ardous waste management laws.

San Benito was the first county to ini­tiate a per-Ion ~business license" tax onminerals. This new 5-cenl-per-ton tax onminerals mined in the county will be usedto pay for road repair. It was initiatedunder Senate 8m 2557 v.fhich grantedcounties new authority to raise revenues.

Review of Nonfue1 Mineral Com­modities. In September. constructionat Amax Gold Inc.·s Hayden Hill mine inlassen County began. In April. GoldfieldsOperating Company celebrated the pour­ing of the one millionth ounce of gokIat its Imperial County Mesquite minewith the opening of the Mesquite MineOverland Trail. The trail introduces thepublic to the gold mine and its uniquedesert environment. The self-guidedOverlook Trail is a cooperative venture ofGoldfields and the U.S. Bureau of LandManagement.

Primary Steel Company discontinuedits Antoch Rat rolled steel plants. Thisresulted in the Tricon division of RelianceSteel and Aluminum Company. Fremont.as the only high-volume flat rolled steel

'" CALIFORNIA GEOlOGY JULY AUGUST 1992

distributor in the San Francisco Bay area.Reliance Steel & Aluminum combinedits two carbon specialists. Tricon andFeralloy West Company. to form theregion's major flat rolled processor.

The U.s. Borax Company consoli­dated its Los Angeles headquarters andAnaheim research offices with a move tothe Valencia area. This location is moreconvenient to its mining operations atBoron. north of Edwards Air Force Base.In February. Newport Mineral Ventures

of Maryland acquired the Death ValleyBille mine from American Borate Com­pany and began limited operations inApril. Manville Corporation sold its Celitesubsidiary to New York-based AlleghanyCorporation. South of Lompoc. Celiteoperated the world's largest diatoma­ceous-earth mining facility.

Some sand and gravel operations werestarted or enlarged. Hillsdale Rock Com·pany was granted a 50-year permit tomine sand and gravel from the Lomerias

Muertas hills north of San Juan Bautistain San Benito County. XTRA PowerCompany was granted a 30-year usepermit to mine sand and gravel fromCottonwood Creek in Tehama County.Granite Construction Company beganbuilding a paving material plant at itsquarry on Pacheco Pass Highway inSan Benito County. Calmat Companywas granted permission to double the sizeof its operations at the South Powayquarry in San Diego County.

NONFUEL MINERAL PRODUCTION IN CALIFORNIA 11

1989 1990 1991elMINERAL

QUANTITY /ALUE" QUANTITY VALUE QUANTITY "VALUE"thousands (thousands) thousands

Boron minerals ............... metric tons 562.311 $429,806 1,093,919 $436.176 1.093,919 $436,176Cement (portland) .......................do. 10,911 642.020 10,032 604,080 8,788 527,280Clays .............................. metric tons 2,195,830 39,243 212,163,515 2140,217 212,160,685 2136.897Gem stones ...... .............................. NA 2.982 NA 1,501 NA 1,500

Gold3/ .............................. kilograms 29,804 366,595 29,607 368.300 33,362 396,866Gypsum (crude) thousand short tons 1,734 13.066 W W W Wlime ............................................ do. 395 24,503 345 19,425 298 16,674

Mercury .......................... metric tons W W 4/ 4/ 4/ 41Pumice ....................................... do. 79,000 4,612 71,739 5,088 W WSand and gravel;

Construction thousand short tons e/138,300 e/670,800 132,214 626,000 115,000 546.300Industrial .............................. do. 2.426 43,863 2.452 48,055 2.000 40,000

Silver31 ........................... metric tons 21 3,650 21 3,209 27 3,466Stone;

Crushed .... thousand short tons 54,887 238,034 e/42,500 e/200,600 34.500 162,900Dimension ................. short tons 28,829 5,564 e/30.077 e/5,213 30,000 5,300

Combined value of asbestos, barite(1990-91), calcium chloride (natural),cement (masonry), clay (fuller's earth1990-91), copper ~989-90}. diatomite,feldspar, iron ore ( y-product 1989.and usable). magnesium compounds,mica (crude 1991), molybdenum. perlite.potash, pumice (1991). rare-earth metalconcentrates, salt, soda ash. sodiumsulfate (natural), talc and pyrophyllite,titanium concentrates (ilmenite 1989-90),tungsten ore concentrates, and valuesindicated by symbol W ............. XX 369,664 XX 421,935 XX 843,826

Total ..... ..................................... XX 2,854,402 XX 2,779.799 XX 3,017.185

e/_ Estimated. NA. Not available. W .. Withheld to avoid disclosing company proprietary data; value includedXX .. Not applicable. with "com!>ijned value" figure.

11. Production as measured by mine shipments. sales. or marketable production (including consumption by producers).21. Excludes certain clays; kind and value included with "Combined value" data.31_ Recoverable content of ores. etc.4/ .. less than 112 unit.

CALIFORNIA GEOLOGY JULY/AUGUST 1992 '23

IHlfi@lJnllfi@1lufrlll of the Second Conferenceon Earthquake Hazards in the Eastern San Francisco Bay Area.

Glenn Borchardtand

Patrick McClellan

DiVision of Mines and Geology e~hibit at Second Conference on Earthquake Hazards.

T his highly successful Second Con'ference was held at Calilornia State

University, Hayward (CSUH) March25-29.1992. Over 400 earth scientists.engineers, and planners attended the90 oral and poster sessions.

The first conference was in 1982and its findings VJere published in theDivision of Mines and Geology (OMG)Special Publication 62. In the interv€ning10 years. many advancements have beenmade in the study of East Bay earthquakehazards. Some that were reviewed andupdated include:

• Estimates of the Holocene slip ratesof the Hayward. Rodgers Creek, andnorthern Calaveras faults (all about8±3 mm/yr). Estimates of probabilitiesfor major earthquakes on the Haywardand Rodgers Creek faults (a[[ are about0.25. or one chance in lour. over thenext 30 years).

• Vast improvements in the measurementprecision of creep rates. strain. and geod­esy along most East Bay faults.

• New geophysical and seismological datarevealing the nature of the connectionsbetwe€n the Hayward and Rodgers Creekfaults and between the Calaveras andConcord faults.

• Recognition that NE-SW tectoniccompression across the Bay region. asVJe[[ as right-lateral strike slip on the majorNW-Irending faults, plays an importantrole in the tectonic regime in the EastBay.

• Numerous Alquist-Priolo Special Studiespinpointing the locations of active faulttraces. These led to a detailed map of theHayward fault (USGS Miscellaneous FieldStudies Map MF-2196) and to the recom­mendation that the Antioch fault beremoved from the list of Holocene-activefaults.

• Recognition that the northern Calaverasfault is a likely source of a major earth­quake in the near future.

• Improved knowledge of the late Quater­nary sedimentation of San Francisco Bayand its influence on earthquake damage.

• Development and refinement of earth­quake planning scenarios lor theHayward and Rodgers Creek faults.

• Progressive State and local programsto abate earthquake hazards of unrein­forced masonry buildings. schools. andother public buildings that lie on or nearEast Bay faults.

During the conference. a two-day fieldtrip was conducted along the Haywardfault. The corresponding field trip guide­book, which includes 34 contributions in225 pages, describes the vast amount ofknowledge gained about the Haywardfault, particularly during the last decade.

The guidebook is based on the new USGSmap.

Another important component of theSecond Conference was a special non­technical forum for 350 Bay area scienceteachers. officials. and citizens. The forumfeatured earthquake exhibits and a panelpresentation by the scientists who aliendedthe previous technical sessions.

The proceedings of the Second Confer­ence will be published b-y the Division ofMines and Geology. The Pioneer Book­store at CSUH sells the 1992 field tripguidebook ($16.00). the 1982 field tripguidebook ($9.00), and the new USGSmap of the Hayward fault (MF-2196)($3.50). Shipping and handling is $4.50for the first item and $2.50 for each addi­tional item.

Pioneer BookstoreCalifornia State University, Hayward

25976 Carlos Bee BoulevardHayward, CA 94536

(510) 881-3507

'" CALIFORNIA GEOLOGY JULY/AUGUST 1992

( Book Reviews)Com.,... moratove Photogr

IN THE FOOTSTEPS OF JOHNWESLEY POWEU..: An Album of Com­parative Photographs 01 the Green andColorado Rivers. 1871-72 and 1%8.By Hal G. Stephens and Eugene M.Shoemaker. 1987. Johnson Books.1880 South 57th Court, Boulder, CO80301. 286 p. $19.95. soft cover.

John Wesley Powell's 1869 and1871-72 expeditions dOYJfl the Green andColorado rivers provide views of some ofthe most extraordinary exposures of geol­ogy anywhere in Ihe VJOrld. Beginning atGreen River, Wyoming in rocks of Tertiaryage (lev..oer than 60 million years oId), theroute travels one vertical mile down thegeologic column to exposures of the Pre­cambrian Era (more than 1.5 billion yearsold) in the Inner Gorge of the Grand Can­yon. To commemorate the centennial ofthe first voyage. the U.S. Geologkal Sor­vey. along VJith the Smithsonian lnSlitutionand the National Geographic Society,sponsored an expedition 10 retrace therouleofPOINeU'S 1871-72suNey.lhepurpose was to rephotograph the viewsfrom the same camera stations used byPOINe1J expedition photographers E.O.Beaman and John K. Hillers. TIle result isan album of comparative photographswhich iUustrates the canyons of the Greenand Colorado rivers over the intervening100 years.

Surprising little change may be evidentin the canyon walls in terms of geologictime. hov.oever the erosional impact of theriver and its tributaries is apparent. Mostdramatic is the pervasive spread through·out the Colorado River region of tamarisk,a Middle Eastern tree planted as a wind­break in the Imperial Valley during theearty part of the century.

A combination of research into PO\.Vell'sexpedition diaries. detailed examination ofthe original photographs. and extensiveknowledge of canyon geology enabled theU.S. Geological Survey crew to identifyISO original camera stations. In a fewcases rockfalls. shifling tributaries. thickvegetation. or inundation by lake watersprevented the team from reaching theexact site.

The book is divided into six chapterscovering different river segments. Opening

essa~ provide both historical and geologiccontext for 110 pairs of photographs.Each pair of photographs is accompaniedby a more detailed description of visiblegeologic features and a commentary on thechanges that have taken place. A glossary.tables 01 geologic lonnations. topographicmap references. and a list of selected read­ings provide additional documentation.Review by Sylvia Bender·Lomb. x

APPUfD SUBSURFACE GEOLOGI­CAL MAPPING. By Daniel J. Tearpockand Richard E. Bischke. 1991. PrenticeHall. Prentice Hall Building. EnglewoodOiffs, NJ 07632. 648 p. $84.00. hard

""'".The increasing use of oil and gas creates

a need for well-trained. well-educated petro­leum geologists. This book is a comprehen­sive work designed for geologists. geophysi­cists, and engineers who prepare subsulfacegeological maps. It VJCJUId also be beneficialto those who use or evaluate subsulfacemaps. to petroleum geology students, andto experienced geologists lNho want to learnmore about subsulface mapping.

The techn~are applicable to relatedfields such as mining, groundwater, andwaste disposal. Chapter topics include:contouring techniques. directionally drilledwells and directional su~, log correlationtechniques. integration of geophysical datain subsurface mapPing. cross sections. faultmaps, structure maps, stlUCturai geometryand balancing. isopach maps. and fieldstudy methodology.x

EXPLORAnON GEOPHYSICS OFTI-IE SHAU.OW SUBSURFACE. ByH Robert Burger. 1992. Prentice HalLPrentice HaD Building, Englewood Oilfs,NJ 07632. 489 p.. two 3-1/2" diskettes.$56.00. hard cover.

This textbook is appropriate foradvanced undergraduate geology studentsand students of other disciplines whorequire some knowledge of geoph~icalmetho.is. Examples, illustrations. problemsets. and applications focus on shallowexploration. After a discussion of the furlda·menials of scismic exploration. the textintroduces the basic theory for each ge0­

physical method: refraction. reflection.electrical resistivity. gravity, and magnetics.

Although equations are developed indetail. mathematical expertise is not neces­sary. Discussion of data collection andreduction procedures is sufficient to allowthe planning of field su~. Althoughnine computer programs "-Tilten for theMacintosh<&\ accompany the text. the textdoes nOl depend on their use. TIley aredesigned to aid comprehension of thetopics and to work with field data. Theyperform direct and inverse modeling andsupport all the major exploration methodscovered in the book. Microsoft Excelspreadsheet templates which producedmost of the tables in the book are also onthe diskettes. Students can access thetemplates. change values in certain cells,and study the effects. The programs re­quire at least System 6.0. Microsol~

Excel Version 2.2 is required to access thetempiates.X

@ M__ iI a r8glS1oJrfld If_II< '" Apple CoMpuloJrrnc: r.Ao::ro«Ill ill regi5loJrfld If-.nan. '" "'_CofporllJOl'l..

V1BROSflS. By Nigel A. Anstey. 1991Prentice Hall. Prentice Hall Building.Englewood oms. NJ 07632. 171 p.$65.00. hard cover.

Vibroseis is a seismic method used todetennine the nature and configurationof rock layers deep in the earth. Its majoradvantages are that it can be used alongroads and can generate a reflect.ion pulseas sharp or sharper than that associatedwith d!,nlamite. Vibroseis provides therequired energy in a long signal of lowpQVJer which is later compressed Inlo ashort pulse. A baseplate is loo.vered intocontad with the ground from a series 01trucks called vibrators. The commandsignal comes ~ radio from the record-ing truck and the baseplates and groundvibrate. Sound waves reflecting off subsur·face rock layers are received by geophonesand recorded. TIle ~;brator operators liftthe baseplates. drive forward. and repeatthe process.

This book documents the history andtechnical aspects of vibro5eis. Some ofthe subjects covered are vibrator electron­ics. the effect of distortion. practkal con­siderations in the field. and the problemof optimizing resolution. There are fiveappendices that provide equations for vari·ous calculations. TIle book is addressed toanyone interested in geophysical explora­tion: students. technicians. processors.interpreters, field geoph~icists. and explo­ration directors. X

CALIFORNIA GEOLOGY JULY/AUGUST 1992 '"

(more book reviews..)

..DATING METHODS APPUCABl£

TO QUATIRNARY GEOLOGIC SlUD­IES IN THE WESTERN UNITEDSTATES. Utah GooIogKal and MroaJSurvey MisceIlaneous Publication 89-7.Edited by Steven L Forman. 1989. UtahGooIogkal and MroaJ Swwy. Oepart­ment of Natural Resources. 606 BlackHa~ Way. Sah Lake Oty. l1T 841 08­1280. 80 p. $6.75 including postage.soft cover.

Except for volcanic extrusives. mostQuaternary rocks cannot be dated by thepopular isotope methods which date themoment of initial crystallization. Fossilsare rare and seldom definitive exceptHolocene and Pleistocene fauna whichhave VJell·knoo.vn distinctions bet\Veenthem. This handy volume presents aSWT\mary of a few techniques that arecurrently in use. They mostly rely on dat­ing materials \Uithin a deposit or on trac·ing the progress of processes involvingthe surface of the deposit. Topics include:radiocarbon dating (using carbon-l4. aradioactive isotope of carbon). dendro­mronology (the >tudy of troe ringiI. so;)dating. sIope-morphometric dating (esti­mating the age of scarp-Iike Iandfonnsl.thennoIuminescence dating (measuringthe energy released as light upon heating).tephrochronology (the study of the datingand correlation of volcanic ash deposits).amino acid geochronology (the study ofthe dating of amino acids in carbonatefossils). and paleothermometry (the deter­mination of temperature during the ge0­logic past). There is also a discussion ofthe application of K/Ar and Ar isotopedating to Quaternary geology. Some ofthe chapters are much more comprehen­sive than others. but together provide abasic introduction to geochronology.Reuiew by Glenn &rchardt.

THEY SAW THE ELEPHANT. ByJoAnn '-"'Y. 1990. The Shoe StringPress. 925 Shennan Avenue. Hamden.cr 06514. 265 p. $25.00. hard cover.

The expression -seeing the elephant~predates the 1849 gold rush. There isa story of a fanner who. on hearing thata circus was in to\lJl1. loaded his wagon\Uith vegetables and headed for the mar·ket there. He had never seen an elephant

and this was an opportunity he coukl notpass up. When he met the circus paradeu.ilich was led by an elephant. his horsebolted in terror and upended his wagon.Seeing his ruined vegetables. the farmercould only say. ~I don't give a hang. for Ihave seen the elephant. ~ To the gold rush­ers the clephant symbolized the vast p0ssi­bilities of fortune or misfortune the journeyto California represented

In this medley of stories, the authorshows the true extent of women's parti­cipation in the gold rush. Most gold rush­ers VJere young. single men. However,it is estimated (based on diaries, letters.and reminiscences) that 18.000 out oflSO.000 forty-niners traveling overlandwere VJOmen. Some came \Uith their hus·bands. lathers. or brothers. Some cameolone.

Many women established homes inthe lawns and camps. others mined goldthemselves. Females worked and lived inevery quarter of society. They were gam­blers. actresses. missionaries. churchbuilders. innkeepers. schoolteachers.and prostiMes. One woman. ElizaFarnham. wrote a book describing howthe captain of the ship that was bringingher around the Hom abandoned her inSouth America and sailed off \Uith herchildren. She found her v.my to Californiawhere she built a t\vo-story house withher 0\lJI1 hands. planted potatoes. anddiscussed philosophy. Mrs. Farnhamdiscoursed on many subjects. One issuedealt \Uith the exaggerated status manyminers achieved simply by claiming it.Pointing out this tendency for misrepre-­sentation. she said. ~If he could blow afife on training days. he will be a professorof music here; if he have buill a pigstyor~I at home, he \Uill be a master­builder in California. ~ In the youthful1andof California one was UJ"Iq,e1y free fromthe censure of Eastern restrictions and.societal expectations. Consider that \VhenJohn Sutter arrived in California from5vJi1zerland he immediately deemed him­self ~captain.- It was never determinedthat he had any miUtary experience at aD.

Women often took on the practicaljobs in business. Twelve of the 23 womenliving in Nevada Oty in 1850 took inboarders or ran hotels, the other threeVJOrked in family-run taverns that acceptedboarders. Apparently there was some

competition in the hotel industry. Theproprietor of Nevada Qty's 8 DoradoHotel. Luzena Stanley Wilson wrote.~J determined to set up a rival hotel. So Ibought two boards from a predouS pilebelonging to a man who was building thesecond~ house in to\lJl1. With my0\lJI1 hands I chopped stakes. droYe theminto the ground, and set up my table. Ibought provisions at a neighboring store.and when my husband came back at nighthe found. mid the VJeird light of the pinetorches. twenty miners eating at my table.Each man as he rose put a dollar in myhand and said J might count him as a per·manent customer...From the first day itwas well patronized. and 1shortly aftertook my husband into partnership."

This book is a fascinating testimonial tothe feelings and achievements of womenliving on the frontier and how they metand dealt \Uith adversity in a land as exoticand new as the experience of seeing anelephant for the first time. Reuiew byMax flanery.

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ROADSIDE GEOLOGY OF TEXAS.By Daru.rin Spearing. 1991. MountainPress Publishing Company. P.O. Box2399, Missoula, MT 59806. 418 p.$15.95. soft """'.

The geok>gic panorama of Texasincludes \dcarUc mesas and thrustingmountains in the \NesI. red canyons in thePanhand~. tropi<al..oo bamen """'"the Gulf Coast. and the limestone plateauson hard granitic terrain in the center of thestate. Rock of aU ages and major types,!Tom Precambrian crystalline gneiss to theloose sands of Holocene beaches. is foundat the surface in the state.

Texas also has an incredible array ofnatural geologic resources. ranging from its

,,. CALIFORNIA GEOLOGY JULY/AUGUST 1992

famous oil and gas fields through practi­cally every rock and mineral resource,including geothermal. lhere is a vastpotential for development of resources inthe Trans-Pecos region of West Texas. inthe Gulf Coast area, and In a belt acrosscentral Texas.

Roadside Geology of Texas explainshow common geologic processes shapedand molded the landscapes you see today.In nontechnical language, the author leadsyou on a )ourney through geologic lime,interpreting the rocks along the highwaysof the Lone Star State.

The seven sections in the book dividethe diverse terrain into cohesive units ofsimilar geology and geography. Eachsection begins with an introductory reviewfollowed by descriptive road Iogs.X

ELEMENTARY HYDROLOGY. ByVijay P. Singh. 1992. Prentice Hall.Prentice Hall BuIlding. EngIewoOO Cliffs.NJ 07632. 973 p. $68.00. soft cover.

Hydrology is a pan of the undergradu­ate curricula of agricultural engineering.civil engineering, environmental sciences.climatology. meteorology, forestry. geogra­phy, and geology. Elementary Hydrologyrequires no previous background in hydrol­ogy. It deals principally with surface waterhydrology with emphasis on the drainagebasin as the origin of surface water.

This book is divided into the follOW'ingpans: 1) the preliminaries including thehydrologic cy:1e. the hydrologic budget,types of watersheds. and the application ofhydrology to environmental and waterresources problems: 2) drainage-basincharacteristics. weather. and the measure­ment and analysis of precipitation data:3) basic concepts of groundwater hydrol­ogy including infiltration. soil moisture,and baseflow: 4) above-surface flow andhydrologic abstractions. and shows thehydrology's relationship to aerodynamics.botany. and agricultural and forest sci­ences: 5) streamflow measurement andhydrograph analysis; 61 the relationshipbetween precipitation and runoff; 7) meth·ods of flow routing through reservoirs andopen channels; 8) watershed simulationand development of watershed models byintegration of the concepts in preceding

sections: 9) hydrologic design in\.clvlngstatistical methods. Exercises follow eachchapter. References are limited to thosethe author deemed most pertinent to thebeginnerS

" '"NATURAL HISTORY OF THE

Wl-IfTE-INYO RANGE. EASTERNCAUFORNlA. Edited by Clarence A.Hall, Jr. 1991. University of CaliforniaPress, 2120 Berkeley Way. Berkeley, CA94720.536 p. $24.95. soft cover.

This natural history guide is modeledafter the nOW"<:lassic Sierra NeoodaNatural History by Storer and Usingerand covers physkal features includingclimate and geology. plants. animals.and archaeology.

The White-Inyo Range-rising sharplyfrom the eastern edge of Owens Valley­is one of the most extraordinary land­scapes in the VJOrld. High. dry and amaz­ingly diverse. it boasts an expansive alpinetundra and features one of the oldest livingspecies on earth-the 4.000-year-01dbristlecone pines. This colorful and author­atative volume is a wealth of informationto hikers and scientists attracted to theWhite-Inyo's altitude and isolation. Thereare descriptions of more than 650 kindsof living things. an eight-color geologicmap, and a roadside guide that enable thevisitor to make sense of the area's com­plex geological history.

For anyone who wishes to visit this as­tonishing area or do research. this volWTleis a unique. comprehensive resource.x

GHOST TOWNS OF mE MOJAVEDESERT: A Concise and Illustrated Guide.By Alan Hensher. 1991. California Clas­sics Books. P.O. Box 29756. Los Ange­les. CA 90029. 64 p. $14.50. soft cover.

This concise and illustrated guide hasdrawn on years of research to chroniclethe histories of nearly 100 southern Cali­fomia desert ghost towns. Much of it hasnever been published. Dozens of rarephotographs document the rise and fall ofsettlements such as Crackerjack. Avawatz,Minneola. Vontrigger. CrOO/ Town.Toeglcity. and Saltdale as well as largertowns such as Calico and lvanpah.

Detailed maps pinpoint the locationsof camps and townsites so the readercan visit them. Histories of the IQIM'lS

and the reasons for their downfalls areprovided.X

THE CAMP CNJY LOCAL FAUNAPaleoenvironment of the Lake ManixBasin. By George T. Jefferson; andABSlllAcrS OF PROCEEDINGS, 1987Mojave Desen Quaternary Research Sym­posium. Quanerly. v. 34. no. 3 and 4.Compiled by Jennifer Reynolds. 1987.San Bernardino County Museum Associa­tion, 2024 Orange Tree Lane. Redlands.CA 92374. 65 p. $7.39 including ship-­ping and tax. soft cover.

The first pan of this publication is astudy of the vertebrate and invertebratefossils recovered from lake and riverdeposits east of BarstOO/, San BernardinoCounty. California. 1he fossils found inthe late Pleistocene Manix Fonnationinclude birds. fish. turtles. and other formswhich lived along the margins of LakeManix. Nearby valleys and slopes thatsurrounded the lake contain fossils ofground sloths. mammoth, cats. horses.camels. and bison.

The second pan includes abstracts of13 papers presented at the 1987 MojaveDesert Quaternary Research Symposium.The papers include topics on paleontol­ogy. racliocakium dating. archaeology.desert soils. and geomorphology.X

QUAlERNARY HISTORY OF TI-fEMANIX FAULT. LAKE MANlX BASIN.MOJAVE DESERT. CAUFORNlA.By Sally F. McGill. Bruce C. Murray.Kevin A. Maher. Jay H. Ueske. Jr..Unda R. ROO/an, and Fred Budinger:and ABSTRACfS OF PROCEfDINGS:1988 Mojave Desert Quaternary ResearchSymposiWTl. Quanerly. v. 35. no. 3 and 4.Compiled by Jennifer Reynolds. SanBernardino County Musewn Association.2024 Orange Tree Lane. Redlands, CA92374.56 p. $7.39. soft cover.

1he first pan of this publication describesthe deformation related to movement alongthe Manix Fault east of Barstow in SanBernardino County. This evidence suggeststhat movement on the fault began beforemiddle Pleistocene time and may have con­tinued into the Holocene.

CALIFORNIA GEOLOGY JULY/AUGUST 1992

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The second part contains abstracts of17 papers presented at the 1988 MojaveDesert Quaternary Research Symposiumincluding titles on paleontology. geomor­phology. stratigraphy, geoarcheology, andphosphate deposits.

NELSON LAKE: Important EarlySites. By Claude N. Warren and Joan S.Schneider; and ABSTRACTS OF PRO­CEEDINGS: 1989 Mojave Desert Qua­ternary Research Symposium. Quarterly,v. 36. no. 2. 1989. Compiled by JenniferReynolds. San Bernardino CountyMuseum Association. 2024 Orange TreeLane. Redlands. CA 92374. 68 p. $7.39including shipping and tax. soft cover.

The first part of this publication is adescription of Nelson Lake archeologicalsites at the Fort Irwin National TrainingCenter, northeast of Barstow. San Ber­nardino County. California. The sitescontain faunal rernains. stone tools. andabundant debris from the production andmaintenance of stone tools. The sites arcthought to be early Holocene.

The second part of the publicationcontains abstracts of papers presentedat the third annual Mojave Desert Qua­ternary Research Symposium. Topicsinclude botanical lineaments. paleontol­ogy. geomorphology and landsliding.interpretation of earth satellite images,and paleomagnetic studies."X

THE MOJAVE RNER FORMATION.MANIX BASIN. CAUFORNlA: Stratigra­phy, Correlation, Magnetostratigraphy.and Rotation. Quarterly. v. 38. no. 2.1991. San Bernardino County MuseumAssociation, 2024 Orange Tree Lane.Redlands. CA 92374. 63 p. $8.89 indOO­ing shipping and tax. soft cover.

The book contains four papers ofvarious aspects of the Mojave River For­mation. Stratigraphy and Intra·basinCorrelalion of Ihe Mojave River Forma­lion. Central Mojave Desert. CalifornIa.by Elizabeth A. Nagy and Bruce C.Murray. describes the lithology, geologicage, and mode of origin of the fonnation.Active faults. including the nearby Manix,have played an important part in the his­tory of the fonnation and the ancestralMo;ave River.

MagnetostrQtigraphy and ClockwiseRotation of Ihe Plio·Pleislocene MojaveRiuer Formation. Cenlral Mojave Oeserl,California is by Christopher J. P1uhar,Joseph L. Kirschvink and Roben W.Adams. One hundred forty-three samplesof the Mojave River Formation were stud­ied for natural remanent magnetism.Results suggest a net clockwise rotationof 8±2.7 degrees over the past 2 millionyears.

Abstracts 01 Proceedings from Ihe51h Annual Mojaoo Desert QuaternaryResearch Symposium. May 17-J8. 199J.Jennifer Reynolds compiled abstracts ofseven papers on plate tectonics, geomor­phology. anthropology, stratigraphy, min­eralogy. paleontology, and paleobotany.

Ancienl ASlronomy of the BlockCanyon Indians: The J991 MojaveDesert Qualernarv Research SymposiumEvening Leclure is by Wilson G. Turner.In this paper Indian petroglyphs at thebase of Tortoise Mountain are interpretedas representing various heavenly bocIies:'

THE WE.ST-CENTRAL MOJAVEDE.SERT: Quaternary Studies BetweenKramer and Afton Canyon. Edited byRobert E. Reynolds. 1989. San Bemar­dino County Museum Association. 2024Orange Tree Lane, Redlands. CA 92374.83 p. $10.08 including shipping and tax,soft cover.

This publication is a collection ofpapers on the Mo,iave Desert nearBarstow. California. The first paper is aguide for a lBO·miJe..1ong field trip fromSan Bernardino. through Helendale,Barstow. Calico. and Afton Canyon onthe ephemeral Mo,iave River. Other topicsinclude those on paleontology. fonnationof lakebeds. detachment faulting, hydrol­ogy. and tectonic and fault studies.X

SOILS IN ARCHAEOLOGY land­scape Evolution and Human Occupation.Edited by Vance T. Holliday. 1992Smithsonian Institution Press. Department900. Blue Ridge Summit. PA 17294.254 p. $39.95 plus $2.25 for postageand handling, hard cover.

This book is a collection of eightpapers presented at the 1988 annual

meeting of the Society for AmericanArchaeology. The papers cover a broadspectrum of soil science applications.including soil chemistry. The essaysdiscuss the use of soils for reconstructingpast landscapes arxllandscape evolution,lor estimating the age of surfaces anddepositional episodes. and for prOl.'ldingphysical and chemical indicators ofhuman occupation.

The first four chapters deal with soilgeomorphology in archaeology. Specifi­cally the use of soils for reconstructinglandscapes and site settings and the useof soils as age indicators are stOOied.

The second group of four essaysdeals with the archaeological significanceof particular allributes of soils and in­dudes both soil geomorphology and soilchemistry.

Because of the potentially broad audioence for this collection of essays, theeditor included a useful glossary of sometenns. largely from pedology and soilmicromorphology. Also inclOOed aresome tenns used in soil description andclassification, soil geomorphology. andsoil geoarchaeology:x

SOIL PHYSICS, Fifth Edition. ByWilliam A. Jury. Willord R. Gardner. andWalter H. Gardner. 1991. John Wiley &Sons. Inc.. 1 Wiley Drive. Somerset, NJ08875-1272.328 p. $49.00. hardcover.

The book, designed for advancedundergraduates or graduate students asUJell as professional scientists. COllers arapidly changing field which has gainedprominence with the grOVJth of environ­mental engineering. Research on thechemical pollution of the environmentis now a global priority. As a result. theonce minor field of solute (solids or gasesdissolved in water) transport through soilis now a mainstream research area ofsoil physics. The \xx)k covers the recentchange from laboratory to Held studyof soil problems. It also addresses theincreased use of mathematics and statis·tics 10 describe soils.

'" CALIFORNIA GEOLOGY JULY AUGUST 1992

"These general topics are covered: thephysical and chemical properties of soil:the properties of water in soils: the theoryof water transpon through saturated andunsaturated soils: the transport of heat.gases. and dissolved solids in soil: solutemovement in soil: and methods of assess­ing the properties 01 spatially variablesoil.Y

INTRODUCTION TO TI-lE PErnOL·OGY OF SOILS AND CHEMICALWEATHERING. By Daniel B. Nahon.1991 John Wiley & Sons. Inc.. 1 WileyDrive. Somerset. NJ 08875-1272.313 p. $59.95. hard cover.

This 000k covers the last 25 yearsduring which petrographic. mineralogic.and geochemical analysis of soils hasmade great advances. The results ofnumerous investigations are summarizedand synthesized. particularily on theweathering soil mantle in tropical areas.Translated from French and concentrat­ing on examples in Africa. the bookemphasizes the value of an interdiscipli·nary approach to the study of soils.

Illustrations include photographs andexcellent line drawings. The reference listis extensive and includes all of the stan­dard citations as well as newer. lesser­known ones. "><:

SOILS AS A TOOL FOR APPUEDQUATERNARY GEOLOGY. Utah Ge0­logical and Mineral Survey MiscellaneousPublication 91-3. By Peter W. Birkeland,Michael N. Machette. and Kathleen M.Haller. 1991. Utah Geological andMineral Survey. Department of NaturalResources. 606 Black HaVJk Way. SaltLake City. lIT 84108·1280. 63 p. $6.50including postage. soft cover.

The last 15 years have se€n a tremen­dous interest in the use of soils for datinggeologic events. Newly deposited sedi­ments undergo the ravages of climatenear the surface of the earth. Percolatingwaters dissolve minerals crystallized athigh temperature and pressure within theearth and precipitate still other mineralsmore in tune with the low temperatureand pressure at the surface. Soil develop­ment takes time. and the QuaternaryPeriod (the last 2 million years) has pro­duced numerous land surfaces that havebeen abandoned by the geologic pro-

cesses that created them. Not surprisingly.the older surlaces generally have soilsthat are redder. deeper. more clayey.and more cemented than the youngersurfaces,

This shon publication is a quick meansfor geologists to get an appreciation ofsoil and how its properties relate to itsage. The authors first explain how differ­ent soils are recognized and described.Concentrating mosUy on the western U.S.they lIlUslrate the effect of lime on theproduction and properties of soils in arie!.semiarid. and subhumid regions, Lastly.they relate numerous case studies in\.lIhich soils have been used to reconstructpast climates. map Quaternary surfaces.and study Quaternary faulting. Quaternarygeologists in Califomia cannot afford tobe without a copy of this book. Review byGlenn Borchardt. ,.

EXPLORING THE SOun;ERNSIERRA: fAST SIDE, 3rd edition ByJames C. Jenkins and Ruby J. Jenkins.1992. Wilderness Press. 2440 BancroftWay. Berkeley. CA 94704. 239 p.$15.95. soft cover.

This book invites you to explore oakand pine forests. alpine meadows linedwith aspen. and chaparral-framed vistas.The region covered includes the moun­tains east of the North Fork Kern Riverbetween the High Sierra and theTehachapi Mountains. Offering ISOadventures that range from backpack tripsto car tours. and from peak climbs to dayhikes. this new edHion includes severalnew trails and more information on daytrips and car trips. Many of the trips aresuitable for equestrians. bicyclists. andcross-country skiers.

cultural history. geology. flora. fauna. andpreservation. A "Tripfinder Table" sum­marizes the trips so the reader can find anappropriate trip easily. Included is a I\vo­

sided, four-color map depicting all thetrips and trailheads. The map also has agrid system which indicates the U.S. Goo-­logical Survey topographic map neededfor every trip.

Whether you are interested in theremote solitude of wilderness. exhilaratingpeak experiences, or accessible scenicpicnic grounds. this book offers a rangeof year-round opportunities. Review byCL Pridmore. 'X'

AFOOT AND AFIELD IN LOSANGELES COUNTY. By Jerry Schad.1990. Wilderness Press. 2440 BancroftWay. Berkeley. CA 94704. 290 p.$15.95. soft cover.

Los Angeles residents who are u:earyof the crov..ds. concrete. and smog willespecially appreciate this guide to localgetaways. Close to half of Los AngelesCounty's 4.083 square miles is wild oronly lightly developed. The 175 hikesdescribed in this book cover over 1.000miles of trails in areas of diverse topogra­phy. climate. and plant and animal life.An Index map outlines the 32 geographicareas that are introduced in separatechapters. A detailed area map accompa­nies the introductory text of each chapterSpecial symbols and capsulized infonna­tion preface each trip description andserve as a convenient means to choosehikes on the basis of difficulty. hiking time.or season. Distance. total elevation gain orloss. recommended maps and eqUipment.and agencies of jurisdiction are listed.Each route is described with additionalnotes on access, parking. camping. natu­ral features. and scenic highlights. Somewalks are recommended for families withchildren. A "best hikes" appendix listsfavorites in various categories such aswildlife watching. autumn colors. wildflow­ers. waterfalls and swimming holes. views.and history. Best beach. canyon. andmountain hikes are also included Adeli­tional chapters give an overview on theclimate. geology. and native flora andfauna of Los Angeles County. TIps onsafety. trail courtesy. and avoiding thesmog are also provided. The guidebook isstudded with numerous black-and-whitephotos':':

CALIFORNIA GEOLOGY JULY AUGUST 1992 '"

(~_~_ea_c_h_e_r_F_ea_tu_r_e~)

T HE QUICKSANDMODEL-ANEXPERIMENT

Level: upper elementary to seniorhigh school

ANTICIPATED LEARNING OUTCOMES

1. Students will describe the differencein stability between dry sand andsand that has become liquid-like.

2. Students will observe what happenswhen water-saturated sand becomesliquid-like.

3. Students will determine whichsediment grain-sizes are prone 10becoming liquid-like.

4. Students will discuss the social impli­cations of building on sedimentsprone 10 becoming liquid-like.

grains is borne by the fluid. So, the morewafer in the openings, the less the grainssupport each other. A very small shakeor jolt on a saturated sand will dislodgethe grains and the whole mass will beginto act like a dense fluid. Some of thewater may be expelled in sand volcanoes.If a heavy object like a road. a buikiing,or even a person is on this liquid·likemass, it may sink.

Sandy sediments subject to water­saturation and a change to a liquid-likestate do not prOllide adequate support forbuilding. Hov.,.oever. the problem will onlyappear when the sediment is shaken orjolted. When these sediments are built onin regions prone to earthquakes. we canexpect problems. Experiences in theMarina District in San Francisco duringthe 1989 Loma Prieta earthquake pro­vide vivid examples (see photo). There,great damage was suffered by structuresbuilt on sandy sediment and loose fillmaterial. all of it water saturated.

Less commonly. sand may alsobecome quick as a resuJt of water beingforced into it. This might happen in astream floodplain after prolonged rainlaUor during flooding when water is suddenlyinjected into a previously unsaturatedsandy sediment. In either instance. thesediment may become fluidized andbehave accordingly.

Materials:

• WKIe-mouth Mason;ar or clear plasticbottle, one quart or larger

• Enough fine saooto fill the;ar orbottle about 113 - 1/2 (use sandboxsand or something similar)

• Quarter or rock small enough to litinto the;ar

• 1-1/2-footlength of plastic. rubber. orglass tubing

BACKGROUND

Quicksand is known 10 most of usonly from mystery stories or horrormovies; few people have first-handexperience with it. The IAJOrd refers to abody 01 sand which, when given ashake or some other shock, acts like afluid. nol like a solid. In the stories ormovies. the hapless victim steps ontothe quicksand. sinks a little. becomesfrightened. and struggles to get outthereby hastening the change to afluidy mass. Then he or she sinks out ofsight. Most sands do not becomeMquick" (subject 10 becoming f1uid-like)VJhen shaken; those which contain a 101of water aTe the culprits. TIlat is whymost quicksands are found near theocean, streams, and swamps.

HOW DOES IT WORK?

In loose. dry sand. the weight of thetopmost sand grains is supported bythe underlying grains. The tiny open­ings between grains are not filled. If allthe openings between grains are filledwith water, some of the VJeight of the

An automobile lies crushed under the thIrd story of this apartment tH.lIlding in SanFrancisco's Manna District. The first two stories are no longer visible because of structuralfailure and sinkJng due to liquefaction, the transformation of the soil from a solid to a liquidstate. Photo by John NaMta. U.S. GeologICal SulVey.

''0 CALlfOflNIA GEOLOGY JULY/AUGUST 1992

(Teacher Feature continued)

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~Jl This experiment was designed by:

James V. O'ConnorDepartment of Environmental SCienceUniversity of the DiSlrict of Columbia

ROCK 11. Washington, D.C. 20008-1154

,,'~ TUBING

Donald L. WoodrowDepartment of Geoscience

lWI) Hobart & William Smith CollegesGeneva. NY 14456

Reprinred from ·Hands·On G60bgy; K·12 ACIlVII>es lindROSCIJrces" WIth pemlI$Sion lrom rhe K-12 Ellrffl ScienceEducation Commiltoo of SEPM (S0C>61y Irx S6dimrmlllryG6o!ogr). CfJPyrighr 1991

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PROCEDURE

l. Put the tubing into the jar sothat one end of it rests on thebottom of the jar and the otherend extends about a foot Oul of

• the jar.

2. Pour all the sand into the jar 10 adepth of 1/3 -1/2, holding thetubing in position while you

POO'

3. Place the coin or small rock onthe sand surface.

4. Very gently pour water into thetubing until all the openings inthe sand are filled and the waterjust reaches the lop of the sand.You should be able to see thewater fill the openings betweensand grains and rise through thesand mass.

5. Let the whole thing sit for aminute or so. then hit the tabletop on which the jar or bottle isresting several times. What hap-pens to the object sitting on thesand surface? What happens tothe sand?

ADDITIONAL ACTIVITIES

l. Try this experiment with marblechips. gravel. or mud. Did any ofthese sediments go quick?

2. Build small structures of materi-als like clay or popsicle sticksand subject them to shocks likeyou did the sand in the jar. Whydo these structures not behavelike the water-saturated sand?

3. Write a paragraph describinghow quicksand gets its name.

4. Imagine you had to build in alocation where qUicksand isknown to develop. Can youthink of a way that you mightavoid its worst effects? Describeyour plan in a paragraph.

CALIFORNIA GEOLOGY JULY/AUGUST 1992 '"

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'32 CALIFORNIA GEOLOGY JULY/AUGUST 1992