GEOLOGYGEOLOGY OFOF A PARTPART OFOF NORTHWESTERNNORTHWESTERN UINTAUINTA COUNTY,COUNTY, WYOMINGWYOMING

byby

FrederickFrederick HustonHuston WingateWingate

A thesithesiss submittesubmittedd ttoo ththee facultfacultyy ooff ththee UniversityUniversity ooff UtaUtahh iinn partiapartiall fulfillmenfulfillmentt ooff ththee requirementsrequirements foforr ththee degredegreee ofof

}1asterMaster ooff ScienceScience

DepartmenDepartmentt ooff GeologyGeology

UniversitUniversityy ooff UtahUtah

JuneJune,, 19611961

f,' I Ton 1\. ov fI LIBRAR-,~.:....Jl LCl.ll YJ. ~TT\T~P':..ITV ( ....,.L~ UNIVERSITU1''i J. '• .L-J.L 1,.fl"J.J....LY J.. O'-'"F UTAHUTAH This Thesis for the Master of Science Degree

Frederick Huston Wingate

has been approved Junel 1961

469251. ACKNOW'LEDG.EMENTSACKNOWLEDGEiMTS

TheThe writerwriter wisheswishes toto expressexpress sinceresincere appreciationappreciation toto Dr.Dr. A.A. J.J.

Eardley,Eardley, ofof thethe UniversityUniversity ofof Utah,Utah, whowho suggestedsuggested thethe problem,problem, andand toto Dr.Dr. wm.Wm L.L. Stokes,Stokes, Dr.Dr. D.D. J.J. Jones,Jones, andand Dr.Dr. N.M. C.C. Williams,Williams, ofof thethe UniversityUniversity ofof Utah,Utah, torfor criticismcriticism ofof thethe manuscript.manuscript. GratitudeGratitude isis furtherfurther tenderedtendered JerryJerry OdekirkOdekirk forfor preparationpreparation ofof thithinn sectioll8sections andand HelmutHelmut DoellingDoelling forfor thethe draftingdrafting ofof illustrationsillustrations andand map3.maps.

TheThe writerwriter wisheswishes toto thankthank hishis wifewife forfor herher assistanceassistance inin thethe fieldfield andand typingtyping ofof thethe manuscript.manuscript. CONTENTCONTENTSS

Page

AbsAbstract·t ract # ••••••••••••••••••••••••••••••••••••••••••••••••••••••• ••#•#*»*•••*••••#•••••••*•«•••••*•••••••••#*«»*•*•••*• v

IntroductioInt roductionn LocatioLocationn anandd accessibilityaccessibility.•••••••«»•»*••»••«*•••«»•»•*•••••••••••••••••••••••••••••••••• • 1 PurposPurposee anandd scopescope,...... a.....*....*.... •••••••••••••••••••••••••••••••••••••••••. 3

'WO 0 •••••••••••••••••••••••••••••••• FielFieldd workrIc. " ...... #...... :3 Geography...... Geography •••••••••••••••••••••••••••••••••••••••••••••••••. 4- TopographTopographyy anandd drainage, •••••••••••••••••••••••••••••• 4 ClimatClimatee anandd vegetatiovegetationn ••••••••••••••••••••••••••••••• 4- LanLandd utilizationutilization,,...... •••••••••••••••••••••••••••••••• G ••••. 5 PreviouPreviouss geologigeologicc worworkk •••••••••••••••••••••••••••••••••••• 5

RegionaRegionall geologygeology•••••••••••••••••••••••••••••••••••••••••• ea...... «....•... 6

Stratigraphat ratigraphyy GeneralGeneral sta.tementstatement...... •••••••••••••••••••••••••••••••••••••••••. 8 CretaceouCretaceouss systemsystem.••*•••.•••..••...•••...... *»•••..•••••••••••••••••••••••••••••••••••• a ••••••••••* S GannetGarulettt groupgroup...... ••••••••••••••••••••••••••••••••••••••••. 8 BearBear RiveRiverr formation. ••••••••••••••••••••••••••••••••• 14 Un.con.fonuity.Unconformity...... *•....«...... o •••••••••••••• " ••••••••••••••••••••••••. 18 Coloradoan-MontananColoradoan-Montanan boundarboundaryy problemproblem. •••••••••••••••••. 20 TertiaryTertiary systemsystem.•••••••«••••.••.•••••••.•••*...... •••••••••••••••••••••••••••••••••••••••••••. 21 EvanstonEvans ton formation. ••••••••••••••••••••••••••••••••••• 21 WasatchWasatch formationformation...... ••••••••••••••••••••••••••••••••••••. 29 Bridger3ridger (?(1)) formationformation...... ••••••••••••••••••••••••••••••••. 35 FowkesFowkes formationformation (see(see nextnext heading)heading).. ••••••••••••••••••. 40

FowkesFowkes formationformation

Type'^yp® localitylocality••••••••••••••••••••••••••••••••••••••••••••• #...... 40 A.geA3...... •••••••••••••••••••••••••••••••••••••••••••••••••••••••. 40 PetrographyPetrography...... •••••••••••••••••••••••••••••••••••••• o ••••••••. 4.3 PetrographyPetrography ofof NorwoodNorwood tuff. ••••••••••••••••••••••••••••••• 56 CorrelationCorrelation...... •••••••••••••••••••••••••••••••••••••••••••••••. 67 ConclusionsConclusions...... •••••••••••••••••••••••••••••••••••••••••••••••. 70 Me8S11redMeasured SectionSection.....«...... *.«...... «.. ••••• e ••••••••••••••••••••••••••••••••••••. 70

1i i11i

StructurStructuree faults••••••••••••••••••*•••Faults ••••••••••••••••••••••••••••••••••••••••••••••••••••••• • ••••••••••••*•••••••••<>••••••• 74 SalSaltt intrusioL~trusionn (1)(?)•••*«**••• ••••••••••••••••••••••••••••••••••••••••••• •«»«»•«•••«•••••••••••••••»«••• 77 FoldFoldss •••••••••••••••••••••••••••••••••••••••••••••••••••••••*•••*•••*••••••**••••• • ••••••••••••••••a*********.••• 80 LandLandslidess Hides ••••••••••••••••••••••••••••••••••••••••••••••••••*••*••••••••*•••**• ••.•••••••••••••••••••••••••••a 81

GeologiGeologicc hist,or'"Jhistory GeneraGenerall statementstatement•••••••••••••••••••••••••••••••••••*•••••• •••••••••••••••••••••••••••••••••••••••••••• 63 CretaceouCretaceouss periodperiod*•••••••••»*••*•***•••»**»••••*••*••«••**« •••••••••••••••••••••••••••••••••••••••••••• 83 TertiarTertiar.yy periodperiod••••••••••••••••••••*••••••*•••••••••*•••••• ••••••••••••••••••••••••••••••••••••••••••• 8.* 86 PaleoeenPaleoeel18e epoch.•••••••••*«**•••••••e::pocl1 ••••••••••••••••••••••••••••••••••••••••• 86 EocenEocenee epochepoch*••••••••••••••»•••••#•••»••••••»•#••••*•• •••••••••••••••••••••••••••••••••••••••••••• 87

GeomorphologyGeomorphology GeneraGenerall sstateuent%atemont• ••••••••••••••••••••••••••••••••••••••••••• ••••••••••••••••••••«<>•••••••••••••••••••• 90 DrainagD rai..nages pattemspatterns•«•••••••••••••••*»••«•«««••••••••«••••••• ...... It •••••••••••• 111- ••••••••• 91 ~ldfo~a ••••••••••••••••••••••••••••••••••••••••••••••• •••• 91

EconomiEconomicc geologygeology GeneraGenerall statement....statement •••••••••••••••••••••••••••••••••••••••••••o ••».<.* 95 CoalCoal*••••••••••••••••••••••••••••••••••••••••••••o«»ee««»»e •••••••••••••••••••••••••••••••••••••••••••••••••••••• »0. 95 Oil••••••••••••••••••••••••••••••••••••••••••••••••••••••••Oil •••••••••••••••••••••••••••••••••••••••••••••••••••••••••o 96 HighwaHighwayy materialsmaterials••••••«•••«•••••••••••••••••••••••••••«•«» •••••••••••••••••••••••••••••••••••••••••••» 97 CeramicCeramic claysclays•••••••••••••••••••••••••••••••••••••••••••••• •••••••••••••••••••••••••••••••••••••••••••••••• 97

Bibliography*••***••*•••*••••*•*••»••**•*••*••••*••••**•*•••••»•Bibliography •••••••••••••••••••••••••••••••••••••••••••••••••••••• 98 ILLUSTRATIONSILLUSTRATIONS

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FigureFigure 1.1, ViewView shoY1ngshowing Gannett-BearGannett-Bear RiverRiver formationformation contactcontact neanearr UpperUpper NarrowNarrows...... s ...... 1313

22.. ViewView showingshowing EvanstonEvanston formatioformationn overlapoverlap onon BeaBearr RiverRiver stratastrata southsouth ofof ShellShell Hollow...... Hollow.. 1919

3.3. ViewView showingshowing Wasatch-EvanstonWasatch-Evanston fonnationformation contactcontact easteast ooff Almy...... Almy.•*••*•*•••«••••••••••••••••••••• 3030

4.4* DiagraDiagramm ooff interpretedinterpreted relationshiprelationship ofof VeatchVeatch'sfs "AlmnA.lmyy formation"formation** andand thethe WasatchWasatch andand EvanstonEvanston formations...... formations•*••» »••••»«••••••••.*.• 3333

5.5. ViewYiew showingshowing BridgerBridger (?)(?) bedbedss inin faultfault con-con­ tactactt witwithh GannetGannettt strata...... strata*•*»•••••*••••*••••••••*••••• 3737

6.6* LocalLocal conglomerateconglomerate lenseslenses andand slightslight cross-cross- laminationlamination inin FowkesFowkes outcropoutcrop inin WhitneyWhitney Canyon...... Canyon 6868

7.7* ViewView ofof FowkesFowkes outcropoutcrop inin WhitneWhitneyy Canyon...... Canyon* «••*••• 6969

8.8* StratigraphicStratigraphic oorrelationcorrelation chart...... chart • 7272

9.9* IdealizedIdealized cross-sectioncross-section fromfrom northeasnortheastt utahUtah to central Uinta County, wyoming...... 73 to central Uinta County, Wyoming «•• 73 10. Trace of fault along the mouth of Shell Hollow...... 76 10. Trace of fault along the mouth of Shell Hollow 76 11. Fowkes formation resting in fault contact with 11* Fowkelowers wasatchformatio stratan restin westg inof faul Alroy...... t contact with 78 lower Wasatch strata west of Almy.. 78 12.12. SmallSmall anticlinalanticlinal foldfold inin WasatchWasatch andand BridgerBridger (1)(?) strata near Upper Narrows...... 82 strata near Upper Narrows.. 82 13.13* StructuralStructural terracterracee onon easteast sideside ooff BearBear RiverRiver Valley...... Valley.•••••*•••••••••••«••.•••**.••*•*•••«••••••#.«• 9292

14.14* StructuralStructural terracesterraces onon wstwest sideside ofof BearBear RiverRiver Valley...... Valley*•••••••••*••••••••••»•••*•*•*••••••••••••*••«• 9393

iiiiii iTIV

P~e

PlatPlatee 1.1* IndeIndexx Map...... a a 2

2.2« GeologicGeologic MaMapp ••••••••••••••••••••...... 0D(in(in pockepockett insidinsidee bacbackk cover)~\cover)

3* GeologicGeologic Cross-Sections .•••••• e»...(i ••• (inn pocketpocket insideinside bacbackk cover)cover) ) / ABSTRACTABSTRACT

TheThe partpart ofof northwestnorthwest UintaUinta County,County, Wyoming,Wyoming, coveredcovered byby thisthis investi­investi­ gation,gation, containscontains bothboth igneousigneous andand sedimentarysedimentary rocks.rocks. TheThe igneouigneouss rocksrocks areare tuffstuffs ofof latelate EoceneEocene age.age. TheseThese tuffstuffs comprisecomprise thethe FowkesFowkes andand Brid­Brid- gerger (1)(?) formationsformations (Veatch,(Veatch, 1907),190?), andand areare thethe youngestyoungest formationsformations ex­ex­ posedposed inin ththee area.area.

ParticularParticular attentionattention isis paipaidd ttoo thethe FowkesFowkes formationformation inin anan attemptattempt toto correlatecorrelate itit witwithh thethe NorwooNorwoodd tuftufff ofof northeasternnortheastern utah.Utah.

MappeNappedd stratastrata rangrangee inin ageage fromfrom Lowelowerr CretaceousCretaceous ttoo latlatee Eocene.Eocene. A majomajorr unconformitunconfonnityy inin thethe sectionsection spanspanss mosmostt ofof UppeUpperr CretaceousCretaceous time.time. A seconsecondd unconformitlli1COnfOrmityy representrepresentss ththee Paleocene-EocenPaleocene-Eocenee transitiotransitionn time.time.

StructuraStructurall featurefeaturess includincludee a majomajorr zonzonee ooff normanormall faultsfaults,, parpartt ooff aa broabroadd synclinesyncline,, a minominorr anticlinaanticlinall foldfold,, anandd landslidlandslidee featuresfeatures.. MostMost faultfa.ultss trentrendd northerlynortherly,, forminformingg a paralleparnilell pattern.pattern.

EconomiEconomicc interestsinterests iinn ththee areareaa centecenterr arounaroundd oiloil,, coalcoal,, clayclay,, anandd high­high­ wawayy constructioconstructionn materialsmaterials.. NNoo economieconomicc productioproduotionn ooff oioill iiss notenotedd aatt thethe timtimee ooff thithiss writinwritingg (1961).(1961).

v INTRODUCTIONINTRODUCTION

LocationLocation andand accessibilityaccessibility

TheThe areaarea describeddescribed inin thi6this !"eportreport isis inin thethe northwesternnorthwestern partpart ofof

UintaUinta CoWlty,County, inin thethe southwestsouthwest cornercorner ofof Wyoming.Wyoming. TheThe a.rea.area containscontains approximatelyapproximately 7272 squaresquare miles,miles, extendingextending norlhwardnorthward frofromm thethe oldold sitesite ofof

A.J..myAlmy Station,Station, WyomingWyoming,, toto aboutabout thethe northnorth boundaryboundary ofof UintaUinta COWlty.County. ItIt includesincludes ththee regioregionn betweenbetween thethe WyomingWyoming - UtahUtah boundaryboundary onon thethe westwest andand thethe weswstt flankflank ofof thethe BeaBearr RiverRiver DividDividee onon thethe east.east. ItIt lieslies approxi­approxi­ matelymately fourfour milemiless northnorth ofof thethe towntown ofof ivanaton,Evans ton, Wyoming,Wyoming, 'Whichwhich isis thethe onlonlyy towto1mn inin ththee immediateimmediate vicinity.vicinity. (See(See IndexIndex MapMap,, PlatPlatee 1.)1.)

ThThee areareaa ii8s accessiblaccessiblee viviaa WyominWyomdJ1gg HighwaHigh~y 8899 andand severaseverall unimprovedunimproved rancranchh roadsroads.. HighwaHighwayy 8899 transecttransectss ththee southwestersouthwesternn cornecornerr ofof ththee area,area, extendinextendingg frofromm EvanstoEvanstonn northwesnorthwestt ttoo WoodruffWoodruff,, UtahUtah.. OnOnee unimproveWlimprovedd roadroad extendextendss nortnorthh alonalongg ththee easeastt sideside ofof thethe BeaBearr FivePiverr vallevalleyy foforr approrl­approxi­ matelymately 8 milesmiles.. A secondsecond unimproveunimprovedd roaroadd intersectsintersects HighwaHighwa.yy 8899 atat thethe poinpointt aatt whicwhichh ththee highwahighwayy crossecrossess ththee UtaUtahh - loominWyowingg statstatee lineline.. IItt ex­ex­ tendtendss frofromm thithiss poinpointt northwardnorthward,, alonalongg ththee weswestt sidsidee ooff BeaBearr RiveRiverr valley,valley, approximatelapproximatelyy 5 milemiless ttoo ththee HewarHewardd Ranch.Ranch.

MosMostt ooff ththee areareaa ofoftf ththee abovabovee describedescribedd ?oad:poadss cacann bbee reachereachedd onlonlyy onon foofoott oorr horseback.horseback.

1 22

I~" \ IDAHOIDAHO I~ \ WYOMINGWYOMING I~ ) la..... 1---- _~/ __LJ..ncoln Coun...!y'--__ I I 1 l~o Uinto Counfy \0 / ...... ,.....,.-...../ , UTAHUTAH COLOCOLO . . \, ""- \ l~ (~ Ie / ... /.?:QJ let: \'0 \~ \

rI

o 5 10 I~~--_~I--_--~I Miles

---WYOMING UTAH -(-I

PlatPlatee 11.. INDEIIJDEXX MHAPP

ShowinShm-ringg ththee reporreportt areareaa iinn northwesternorth1'lesternn UintUintaa CountyCounty,, looming~y.Joming.. PurposePurpose andand scopescope

TheThe purpospurposee andand scopescope ofof thithiss reporreportt isis fourfold:fourfold:

1.1* TheThe FowkeFowkess formationformation waswas studiedstudied inin detaildetail ttoo obtaiobtainn a betterbetter underatandingunderstanding ooff itaits origin.origin* AnAn attemptattempt hahus alaoalso beebeenn madmadee ttoo correlatecorrelate thethe FowkesFowkes formationformation withwith thethe NorwooNorwoodd for.mationformation ooff northeasternortheasternn Utah.Utah*

2.2* InIn thethe lighlightt ofof ththee recent, discoverdiscoveryy bbyy TracTracyy & OrielOriel (1959)(1959) thatthat ththee FowkesFowkes formationformation isis stratigraphicallystratigraphically highehigherr thanthan ththee KnightKnight formation,formation, ratherrather thanthan beinbeingg betweebetweenn thethe KnighKnightt formationformation andand AlmAlmyy formationformation asas de­de­ scribed.scribed bbyy VeatchVeatch (1907),(1907), a studystudy hahaas beebeenn madma.dee ofof ththee relationshirelationshipp betweenbetween ththee AlmyAlmy andand KnighKnightt formations.formations* A questioquestionn hahass arisenarisen asas ttoo thethe validityvalidity ofof thethe AlmyAlmy for.mationformation (Eardley,(Eardley, 1959).1959)*

33.* TheThe uppeupperr portioportionn ofof VeatchtsVeatchfs BeckwitBeckwithh formationformation (1907)(1907) hahass beenbeen correlatedcorrelated withwith thethe GannettGannett groupgroup ofof southeasternsoutheastern IdahIdahoo (Burger,(Burger, 1955).1955)*

AnAn attemptattempt hashas beebeenn mademade ttoo subdividesubdivide ththee uppeupperr BeckwitBecladthh andand ttoo correlatecorrelate sucluohh subdiYiaionasubdivisions withwith thosethose ofof ththee GannetGannettt group.group*

44.* DetailedDetailed stratigraphicstratigraphic andand structuralstructural datadata werewere collectecollectedd inin or­or­ derder toto preparpreparee a geologicgeologic mapmap,, meaauredmeasured stratigraphicstratigraphic sections,sections, anandd atl'l1c­struc­ turaltural cross-sectionscross-sections foforr thethe area.area*

FielFieldd liOrkwork

FieldField workwork wawass conducteconductedd duringduring thethe SUJDm.ersummer ofof 1960.I960*

BueBase andand geologicgeologic mapsmaps werewere preparepreparedd fromfrom aerialaerial photographphotographss procuredprocured fromfrom ththee UU.* S.S. DepartmentDepartment ofof AgricultureAgriculture,, CommodityCommodity StabilisationStabilization Service,Service, PerformancePerformance Division.Division. ContactContact pr1.ntsprints werewere takentaken fromfrom projectproject CVT,CVT, flightflight

Itripstrip lB,3B, photosphotos 143143 throughthrough 155,155. andand flightflight stripstrip 2B,2B, photosphotos 1414 throughthrough

26.26. 14apMap scalescale waswas setset atat 1:21,1:21, 120120 (J(3 inches.inches • 1 mile).mile). HorizontalHorizontal con­con­ troltrol forfor photophoto assemblyassembly waswas takentaken fromfrom U.U. S.S. DepartmentDepartment ofof thethe Interior,Interior,

GrazingGrazing Service,Service, WyomingWyoming MapMap NumberNumber 33,33, preparedprepared inin April,April, 1944.1944. ControlControl waswas laterlater adjustedadjusted toto sectionsection cornerscorners foundfound inin thethe field.field.

TheThe buebase mapmap waswas constructedconstructed byby useuse ofof radial-lineradial-line templatestemplates andand Kai1Kail

PlottingPlotting Maohine.Machine.

ElevationElevation datadata areare notnot availableavailable inin thethe reportreport area.area.

StratigraphicStratigraphic sectionssections werewere measuredmeasured byby thethe Brunton-tapeBrunton-tape method.method.

GeographyGeography

TopographYTopography .!ill!and drainage.drainage. TheThe areaarea isis oneone ofof mediummedium relierelieff (approxi­(approxi­ matelymately 800800 feet)feet) andand consistsconsists primarilyprimarily ofof low,low, flat-toppedflat-topped hillshills andand ben­ben­

ches,ches, borderingbordering eacheach sideside ofof thethe BearBear RiverRiver valley.valley. ElevationElevationss rangrangee fromfrom

6,706,7000 feefeett inin ththee riveriverr valleyvalley ttoo abouaboutt 7,507,5000 feetfeet oonn totopp ooff ththee higherhigher

peakspeaks..

TributarieTributariess thathatt draindrain ththee areareaa toto ththee BeaBearr RiveRiverr becombecomee drdryy iinn latelate spring.spring. ThThee drainagdrainagee patterpattemn iiss dendritic.dendritic.

Cll.ry.teClimate iB!!and vegetationvegetAtion.. ThThee climatclimatee iiss generallgenerallyy drdryy anandd coolcool.. Win­Win­

tersters araree quitquitee coldcold,, witwithh a faifairr amounamountt ooff snowsnow.. SprinSpringg anandd falfalll seasonsseasons

araree ooff shorshorl:.t duratiodurationn anandd summerssummers araree relativelrelativelyy coocooll anandd dry.dry.

VegetatioVegetationn throughouthroughoutt ththee areareaa consistconsistss chieflchieflyy ooff sagebrussagebrushh andand

greasewoodgreaeevood,, witwithh somsomee smalsmalll cedacedarr treetreess growingrowingg iinn ththee highehigherr elevations.elevations. 5

A veryvery fewfew largelarge cottonwoodCottonwood treestrees areare foundfound locallylocally nearnear surfacesurface springs.springs.

~Land utilizat:i.on.utilization. TheThe landland isis utilisedutilized primarilyprimarily forfor grazinggrazing ofof

cattlecattle andand ,beep.sheep. A veryvery smallsmall amountamount ofof farmingfarming isis conductedconducted alongalong thethe

narrownarrow riverriver valley.valley. LivestockLivestock feedfeed isis thethe prinoipalprincipal produce.produce.

PreviousPrevious geologicgeologic workwork

NumerousNumerous scientificscientific explorationsexplorations ofof southwestsouthwest Wyominglooming werewere conduotedconducted

priorprior toto 1900.1900. AmongAmong thethe earliestearliest ofof tbethe explorersexplorers werewere Bonneville,Bonneville,

Fremont,Fremont, Clayton,Clayton, Beckwith,Beckwith, Stansbury,Stansbury, andand Eng1emann,Snglemann, dur.i.ngduring thethe yearsyears

18341834 toto 1858.1858. TheseThese earlyearly investigationsinvestigations werewere oonoernedconcerned prima.rilyprimarily withwith

thethe studystudy ofof thethe coal,coal, oil,oil, andand paleontologypaleontology ofof thethe region.region.

FederaFederall LanLandd OffioeOffice sUI7eyssui /eys bbyy HaydenHayden (1869-1874)(1869-1874) andand KingKing (40th(40th par­par­

allel,allel, 1876)1876) inCludedincluded a generalgeneral reconnaissanoereconnaissance ofof southwestsouthwest Wyoming.Wyoming. C1ay­Clay-

burneburne andand DurkeeDurkee,, ofof ththee UnionUnion PacificPacific Railroad,Railroad, .Meek,Meek, andand MarshMarsh oonductedconducted

furtherfurther studiesstudies inin thethe areaarea durinduringg thethe perioperiodd 18721872 toto 1877.1877.

FurtherFurther investigationsinvestigations nrewere conduotedconducted fromfrom 18791879 toto 19001900 byby Ward,Ward, White,White,

Stanton,Stanton, AhemAhern,, KnightKnight,, anandd others.others.

VeatcVeatchh (1907)(1907) publishepublishedd a comprehensivcomprehensivee geologigeologiCc anandd geographigeographicc reportreport

ooff southwestsouthwest domingvqoming.. ThiThiss worworkk hahass serveservedd aass ththee basicbasic geologicgeologic referencereference

inin ththee area.area.

MansfielMansfieldd (1927(1927)) madmadee aII. majomajorr contributiocontributionn ttoo ththee geologicgeologic studiesstudies ofof

adjacentadjacent areaareass iinn northeasnortheastt UtaUtahh anandd southeassoutheastt Idaho.Idaho.

TheThe UniversitUniversityy ooff Utautahh hahass sponsoresponsoredd a numbenumberr ooff investigationinvestigationss ooff thethe 6

ggeologoolo87y otof .outhsouthwes.... t l(yomingWyoming ondand odjacentadjacent partpartes ootf Utah.Utah. Dr.Dr. A.A. J.J. EardleEardle;ry

(1(1949949,, 11951951,, 11952952,, 19519599) hahass publipublishe8hodd ....severaral l ""rIaoworks conc.m1ngconcerning thethe ggenera.n.rall

reregiongion,, andand baahas directeddirected severa.evera!l thesitheai.8s studieItudi.. s inin ththee areaarea.. P&rt.aParts ofof louth­south­

.....west t l(yominWyoming ondand atIjac.ntadjacent UtaUtahh havhaTee beenbeen includeincludedd inin unpublisheunpublishedd ththese.... s otof thethe UniversitUniversit;ry bbyy MounIIountt (1952)(1952),, RandallRandall (1952)(1952),, StaStarrkk (1953)(1953),, WooWoodd (1(1953)953),,

BBarretarrattt (1(1953)953 ) , LarseLars.nn (1954),(1954), NixoNixonn (1955), BurgeBurg.rr (1955)(1955),, MadseMaAsenn (1959),(1959), andand othersothers.. DrDr.. WW.. LL.. StokeStokeas anandd Dr.Dr. N.. C.C. WilliamWilli... s havhavee conducteoonductedd impor­impor­ tantantt .tstudieudie.s ooff adjacenatIjacentt areaare.. s iinn northeasnortha.. t UUtahtah..

ThTh.e U. S8 .. GeologicalGeological Survey;r begabegann a prograprogr... m ooff detailedetailedd geologigeologicc in­in­ vestigatiovaatigationn ootf southwes.outh..... t l(yomingdoming iinn 11959959 . ResultReoultas ootf thithi.s investigatioinvaatigationn arsare inincompletcOiliplatae ttoo datdatee (1961)(1961),, althougalthoughh a preliminarprslimina17y reporreportt hahass beebeenn publishedpublished

(Trac(Trocy;r anandd OrielOriel,, 11959)959) ..

RegionaRegionall ggeologoolo87y

ThTheo geologgoolo&7y ootf southwester.outh_ternn WyominWyomingg i10s typifietypifiedd bb;ry broabroatld foldsfolds,, thrustthrust faultraultas ooff greagreatt magnitudemagnitude,, anand.d thickk sedimentar.edimentaryy strata.strata.

ThThee areareaa ibs situatesituatedd slightlslightlyy weswett ooff a& majomajorr zonson.e ooff foldingg andand thrustingthrusting.. IItt i10s characterizecharoctorizedd bb;ry continentacontinentall sedimentlad1mantas anandd extrusiveextrusive igneoui gneouss rocksrocks,, and norma normall r&ulte.faults.

The BeaBearr RiveRiver DividDividee oonn ththee easeutt i18s a• complexlcomplexlyy foldefoldedd anandd faultedfaulted sequenc.equencee ooff JurassiJUrMaicc througthroughh TertiarTertiaryy sedimentseed1Ir.enta,, anandd iiss separate.spar.tedd fromfrom ththoe reporreportt areareaa bb;ry a largLargee normanormall faultfault,, designatede.ignatedd ththee Acock!cockes FaulFaultt b;rby

VeatcVeatchh (1907)(1907).. AcockAcockes FaulFaultt extendextendss northwarnorthwardd frotromm ththee vicinitvicinity;r ootf Evans­Evans- tonton,, WyomingWyoming,, ttoo ththee SalSaltt Creekk BasinBu in,, wherweree iitt mergemerge.s wit1d.thh ththee MeMedicindicinee

ButtButtee FaulFaultt (Veatch(Veatch,, 1907)1907).. ThThoe MedicinMedicinee ButtButtee FaulFaultt borderbordorss ththee BBea.arr 77

RiverRiver DivideDivide onon thethe eut.east. ItIt isis alsoalso a normalnormal fault.fault.

TheThe orestcrest ofof thethe BearBear RiverRiver DivideDivide approximatelyapproximately marksmarks thethe axisaxis ofof thethe F~ckRock Creek-Need.lesCreek-Needles AnticlineAnticline (Veatah,(Veatch, 1907).1907). A bl"CJad.broad aynclir..esyncline lieslies toto thethe easteast ofof thethe BearBear RiverRiver Divide.Divide. ThisThis h68has beenbeen te:nnedtermed thethe FossilFossil

SJ:nc1ine~Syncline, oror FoseilFossil Basin,Basin, (Veatch,(Veatch, 1907)1907) andand extendsextends northwardnorthward fromfrom anan areaarea approximatelyapproximately 1010 milesmiles easteast ofof Evanston"Evans ton, forfor aboutabout 7575 miles.utiles.

A secondsecond synoline"syncline, AlkallAlkali SynclineSyneline (Veateh,(Veatch, 1907)1907) lieslies slightlyslightly wetwest ofof thethe BearBear RiverRiver Divide.Divide. TheThe southei"'l1southern nosenose ofof thethe AlkaliAlkali SynclineSyncline isis includedincluded inin thethe nort.hernnorthern qua.rt:.erquarter ofof thethe reportreport area.area.

A majormajor thrustthrust fault;fault, th.the A.baarokaAbsaroka thrustthrust (Veatch,(Veatch, 1907),1907). bordersborders thethe easteast flankflank ofof FossilFossil Basin.Basin. STRATIGRAPHYSTRATIGRAPHY

GeneralGeneral statementstatement

StrataStrata exposedexposed inin thethe areaarea coveredcovered byby thisthis :reportreport rangerange inin ageage fromfrom

EarlyEarly CretaceousCretaceous toto Recent.Recent. SeveralSeveral omissionsomissions inin thethe stratigraphicstratigraphic re­re­ cordcord representrepresent longlong periodperiodss ofof erosionerosion Oror non-deposition,non-deposition, oror both.both. Con-Con­ solidatedsolidated stratastrata consistconsist predominantlpredominantlyy ofof sedimentsedimentss ofof fluvialfluvial andand lacus­lacus­ trinetrine origin.origin. A thithinn sequencsequencee ofof EocenEocenee volcanivolcanicc derivativesderivatives occursoccurs atat ththee totopp ooff thethe consolida.tedconsolidated section.section. QuaternaryQuaternary alluviumalluvium occupieoccupiess thethe highesthighest stratigraphicstratigraphic position.position.

ThThee compositecomposite thicknessthickness ofof exposedexposed rockrockss isis approximatelyapproximately 4,0004,000 toto

4,5004,500 feet.feet. FormationsFormations mappedmapped inin ththee EvanstonEvanston areaarea maymay bbee correlatedcorrelated 'Withwith muchmuch thickethickerr sectionsectionss ttoo ththee euteast anandd northnorth.. ThicThickk continentacontinentall sequencessequences iinn northeasnorlheastt Utautahh araree ofof greatlgreatly-y differendifferentt lithologlithologyy thathann ththee EvanstonEvanston section.section. ThThee northeasnortheastt UtaUtahh depositdepositss ara.ree predominantlpredominantly-y sandstonsandstonee anandd con­con­ glomerateglomerate.. ThThee northwesnorthwestt UintUintaa CountyCounty depositdepositss consisconsistt ooff calcareoucalcareouss sand­sand­ astones tones,, 1Lll.estones,limestones, shales,shales, anandd minominorr amountamountss ooff conglomeratoe.conglomerate.

ConsolidateConsolidatedd rockrockss exposeexposedd iinn ththee arearea.a araree divisibldivisiblee intintoo sisixx unitsunits suitablsuitablee foforr mapping.mapping*

CretaceouCretaceouss systemsystem

GannetG&Q11ettt groupgroup_. MansfielMansfieldd (1927(1927)) namenamedd ththee GannetGannettt grougroupp frofromm exposuresexposures

a8 99 inin thethe GannettGannett HillsHills ofof southeasternsoutheastern Idaho,Idaho, andand divideddivided itit intointo fivefive mem-mem­ bars:bers: TygeeTygee lJandatone,sandstone, DraneyDraney limestone,limestone, BechlerBechler conglomerate,conglomerate, PetersonPeterson limestone,limestone, andand EphraimEphraim conglomerate,conglomerate, fromfrom toptop toto base.base*

TheThe lowelJtlowest exposedexposed rocksrocks northnorth ofof EvanstonEvanston werewere mappedmapped asas upperupper Gan-Gan­ nettnett group,group, andand effortsefforts toto subdividesiibdivide themthem werewere unsuccelJsful.unsuccessful. ThereThere areare nono stratigraphicstratigraphic b:reaksbreaks inin thethe sequence.sequence. SimilarSimilar lithologylithology andand strati-strati­ graphicgraphic positionposition suggestsuggest a possiblepossible correlationcorrelation betweebetweenn thethe GannettGannett ex-ex­ posuresposures nearnear EvanstonEvanston andand thethe TygeeTygee andand DraneyDraney membersmembers ofof thethe typetype Gannett.Gannett.

TheThe TygeeTygee andand DraneyDraney members,members, inin theirtheir typetype localities,localities, areare approximatelyapproximately

600600 feetfeet thick,thick, whereaswhereas ththee partpart ofof thethe GannettGannett groupgroup exposedexposed northnorth ofof

EvanstonEvanston isis onlyonly appro:x;i.:matelyapproximately 400400 feetfeet thick.thick. NoNo fossilsfossils werewere foundfound inin thethe GannetGannettt groupgroup byby thethe writer,writer, whicwhichh precludeprecludess definitedefinite correlationcorrelation withwith membermemberss ofof ththee typetype GannettGannett group.group.

BurgerBurger (1955)(1955) correlatecorrelatedd ththee unitsunits ofof thethe BeckwitBeckwithh formationformation (Veatch,(Veatch,

1907)1907) withwith ththee PruessPruess,, stump,Stump, andand GannetGannettt formationformationss ofof southeasternsoutheastern Idaho.Idaho.

AccordinAccordingg toto BurgeBurgerr (1955):(1955):

nttTheThe GannetGannettt sedimentsedimentss represenrepresentt alternatinalternatingg periodsperiods ooff orogenyorogeny anandd quiescencquiescencee inin stonstonyy deserdesertt anandd fluvialfluvial environmentsenvironments• .nn

ThThee Jurassic-CretaceouJurassic-Cretaceouss boundarboundaryy iiss believebelievedd ttoo liliee withiwithinn ththee EphraimEphraim conglomerateconglomerate membememberr ooff ththee GannetGannettt grougroupp (Cobba(Cobbann andand ReesideReeside,, 1952;1952;

BurgerBurger,, 19551955;; anandd Stokes,Stokes, 1959).1959).

GannetGannettt exposureexposuress nortnorthh ooff EvanstoEvanstonn araree overlaioverlainn bbyy blackblack,, carbonaceous,carbonaceous, fossiliferousfossiliferous shaleshaless ooff ththee BeaBearr RiveRiverr formatiofonnationn ooff CenomaniaCenomaniann agagee (se(seee fig­fig­ ururee l)1).. ThThee contaccontactt appearappearss confonnable.conformable. 1100

ThThee followintollo1lingg sectioaectionn wa...... s measureured d approximatelapprox1m&telyy 4i milmilee soutaouthh oorf thethe

UppeUpperr NarrowsNarrow,, iinn sectioaectionn 55,, TT.. 17 N«N.,, RR.. 121200 W»w.,:

BeaBearr RiveRiverr formationformation UppeUpperr GannetGannettt grougroupp FeetFeet

SandstoneSandstone,, fine-grainedfine- grained,, thick-beddedthick-bedded; browbrownn ttoo lighlightt brownbrow,, watheweatherinringg dardarkk browbrownn ttoo red-brownred-brown;; alislightlghtlyy calcareous••••••••••••#•••••••••••*••••••••••••••calc.reoua...... • 11 CovereCovered.d slopeelope;; yellow-browyellow-brownn ttoo brownbrown anandd grag ~y clac~y float••••••••••••••••••••••••••••••flo.t...... • 11 SandstoneSandatone,, fine-grainedfine-grained,, massivemuely.;; brownbrown ttoo yellow-brown;y.ll~brown;; calcareou...... calcareous....• ...... 11 Limestone.I..1.mntone,, nodularnodUlar;; thin-bedded,thin-bedded, weathereweathers intintoo platesplate. ;; darkdark gragrayy ttoo black;black; containcontain8s a fewfew,, poorlpoorlyy ppreservereservedd pel.cyp0d8...... pelecypods•••••••••••••••••••••••••••••••••••••••• 11 LimestoneLimNtone;; massivmaaaivee cryatalline;crystalline; darkdark gragraty ttoo blackblack,, weatherveathe.rws brown toto yellow—browy.ll~brown.n ...... •••••••••••«•«•«••••.•...... • 11 OovaredCovered .lope...... slope 11 Lime.tone;Limestone; musiy.massive crystallineCr)'8t&l.lin.;; darkdark brom,brown, ....weatherth.re s lightlight brolll'lbrown toto lighllghtt ggray•••••••••••••••••••••••••••••••••••••••ray...... • 77 CoveredCovered Ilopeslope;; yyellow-brow.Uo.... brom n ttoo brolmbrown claclaTy flo.t...... float*•••••«•••••••••••••••••«•«••*•#•••*•«•• 1010 Limeltone;limestone; mu.ivemassive cryatalline,crystalline, thick­thick- bedded,bedded, w.thereweathers intointo blocky,blocky, rectangularrectangular tragmanta;fragments; graygray toto ggray-brownray-brow,, ...weatherthere s lightlight brotmbrown tQto ggray-brown*.•#*•••••••~-brown...... • *•••»«.. «.««.*•••.•••... 77 CoveredCovered Ilope;slope; flo.tfloat containacontains Im&ll,small, angularangular fragmantafragments ooff gragrayy toto ggray-brownra;y-brovn,, calcareouscalcareous .hale...... shale ...... 7 Mudotone;Mudstone; Slislightlghtlyy bentoniticbentOnitiC;; darkdark andand lilighght ggrayray;; ...weatherthere s intointo smallsmall angularangular fragment...... fragments*»••••»•••••...•*•.•...... • ...... 1414 Mudstone;Mudstone; red.red andand ggreen-grayreen-g~;; ..weatherthere s intointo small,small, angularangular cbipe;chips; elope-slope- lormerformer*...... ••••••.••••.••••*••»••#•»•*•••*»••»*•••.»•...... • 22 CoTeredCovered .lope...... slope...*•.«•*«••..•«*•••«•....••...••••.•••*•...... 1010 Mudstone,Mudstone, liltsilty)";; blue-blue-gragra;yy toto gr-.v;gray; .lope-foslope—fo rmer.rmer•.«.».«..«.»*..«...«.«.....«.««.«.«*...... 33 1111

LimestoneI.1meeton., J fine-grainetine- grainedd cryatalline;crystalline; brownbro~,, weatherw.theres yyellow-brownellow-brow; containconta1nos small.man,, dardarkk blue-blue-grag~y limestonlimo.ten.e nodulesnoduJ.,•• , , givingivingg thethe appearancappearancee ootf pebblpebblee conglomerate.••**•»»•»••*•••«conglomerat...... • 11 CovereCoveredd slope*••*«•••••••«»*••••••*«••••••••*•«•••••••«.lope...... * 5 LimestoneLime.tone,, fine-grainetine-grainedd cr,yatallinecrystalline; nodularnodular;; brownbI'Ollrl,, weatherwathens lightlight brown*••«•••**•••••*•••••«•**••••••••••*••*•••••••brown...... • 11 CovCoverede red slope••••••••••••••*•••••••••••••••••••••••*•••.lope...... • 5 limestoneu.m..tone;; fine-graineline-grainedd c:ryatall1necrystalline; olivolivee green*•«•**••••«•••«••••**•«•**•**•••*••*••*gre.n...... •. i4f CovereCoveredd slopeelope;; browbrownn anandd yellow-brownyellow-brown claclayy float••••••••••••••*•••••••••••••«••••••••«••float...... • 11 Mudstonelfudotene;; green-gragroen-gl'lYy anendd lighlightt broWl;brown; containconta.in8s greegreenn anandd brown limylimy nodulenodUl...... s * * 7 LimestoneL1.meatone;; massivmulivee crystallinecryatalline;; nodular;nodular; lighlightt green-grayg reen-g~;; ledge-formeledge-former...... r * *••••*•*•...... • 11 CovereCoveredd slope••••••••••••••••»•••«•••••••••••••••••••*•.lope...... • 1010 limestoneLimeIItone;; massivlllU8ivee cryatallinecrystalline;; nodular;nodular; lighlightt greeft-graygreee-g ~j; lledge-former*.edge-former...... * ...... 5 CovereCoveredd slope*»•••.lope...... * * * * *••*««•••*••«••••••••»•••••*•••»•...... • 111 1 limestoneL1.:me.ton. ;; massivmuaivee cr,yatal.l1necrystalline;; nodular;nodular; lighlightt greengreen-gray-gray;; ledg.-former.....ledge-former* .....* ...... ••••• 1313 S&ndeton.,Sandstone, fine-grainedfin.- grained;; aalt-arui-pepperaalt-and-pepperi; thick-beddedthick-bedded;; lilighghtt grayg~;; lledgeodgo-- tormerformer*•••••••••*••••**••••*•*•••«*•••••••«•••••••...... • 22 CovereCov.redd slope.lope...... * * * * * * * * * *••••••*•*••««***••••«•••••••••*• • 10 10 S&ndatone,Sandstone, fine-grainedfine-grain.d;; calcareouscalcareoua;; ggral'l3'y ttoo ggray-brownr,v-bro.n;; ledge-former...... ledge-former** ...... 11 ClaystoneCle;yotcno;; darkdark endand lighlight graygro.Y;; finolyfinely powderedpowdered;; elope-formeslope-formerr.* ...... * * *.• ...... •••••••••••. 99 Sandatone.Sandstone, calcareouacalcareous;; containcontainas l.:imy'limy concretionsconcretion.;; thick-beddedthick-bedded;; llghtlight ggray~;; lledge—former*••••••*••«•••••*••••*••••••••••edg.-former...... • J3 MudatoneMudstone .., calcareoua,calcareous, nodul.ar;nodular; thin­thin- beddedbedded;; reredd andand ggrayr.;y;; cocontainntainas aa thinthin limestonl.1meatonee bed;bed; crystallin.;crystalline; darkdark ggrayr.,;; aapproximatelpproximate17y iJ footfoot thithickck..* ••...... 66 Sandatone..Sandstone, calcareous;calcareous; coot&i.nacontains limylimy nodulnodules.. ; thicthick-beddedk- bedded;; lightlight gra;rigray; ledg.-former...... ledge—forme r*•••••••••••»•••••••••••••••••••«•••••...... » X1 CoveredCovered elopeslope; red-brown toto redred-gra-g ~y clcla.,y float...... float*•*••••»*••••••••*•••••••»•••*•••••••••«• 66 12

Shale,Shale, calcareousc81care~U8,, caroonife::""Ousicarboniferous; darkdark gragrayy ttoo blackblack,, weatherweatherss lightlight gray...... gray ...... 11 Claystone;Claystone; calcareous;calcareous; reredd andand gray;gray; weathersweathers intointo small,small, angularangular frag-frag­ mentsments,, oror Chips...... chips* »•••.•**•••••••*••••*••••*•*#•*•*•<»» 22 Sandstone,Sandstone, calcareous;calcareous; limylimy concretions;concretions; lightlight gray;gray; weatherweatherss intintoo small,small, roundedrounded fragments;fragments; ledge-former...... ledge-former*•*•••«•*«••**.*•*.* 6 CoveredCovered elope;slope; red,red, gray,gray, andand green-green- graygray claystoneclaystone anandd mudstonmudstonee float...... float** •••«••••• 2222 Limeetone;Limestone; cr.retalline;crystalline; nodularnodular;; lightlight graygray;; weatherweathel"'8s intointo small,small, roundedrounded fragments;fragments; containcontainss somsomee interbeddeinterbeddedd blue-blue- gragrayy claystone...... claystone*•••••*•»..«.•««•*.•«••••••••»••••••• 1414 Limestone;limestone; cryatalline;crystalline; nodular;nodular; lightlight graygray toto gray-brown;gray-brown; weatherweatherss intointo blockyblocky,, angularangular fragments...... fragments «•*••**«• 11 CoveredCovered elope;slope; reredd anandd grag~'y clayclay float...... float * * 2323 Limestone;limestone; cr,ystalline;crystalline; blue-grayblue-gray nodulesnodules;; darkdark graygray,, weatherweatherss lightlight gray;gray; thin,thin, interbeddedinterbedded graygray claystone...... claystone**•••*••••••• 1010 Umestone;limestone; sugarsugaryy texture;texture; sandysandy appearance;appearance; lightlight graygray toto gray-gray- brownbrown* ••••••••••••. • . * o...... * 9 CoveredCovered elope;slope; redred andand gragrayy clayclay float...... float * 1212 LimestoneLimestone;; massivmassivee crystalline;crystalline; con-con­ cretionarycretionary;; red-gra,y"red-gray ttoo gray;gray; ledge—former•«•«••••••••**•«••••••••••••••••••••••ledge~fonner...... • 2323 CoveredCovered elopejslope; redred andand graygray clayclay float...... float...* 1515 Clayatone;Claystone; redred andand graygray;; interbeddedinterbedded limestonelimestone;; crystalline;crystalline; nodular;nodular; gr~gray ttoo gray-brown...... gray-brown•*«•*«•*••••..•*••*•«••*•••»«.••* 1212 Sandstone;Sandstone; salt-and-pepper;salt-and-pepper; graygray;; upperupper parpartt thin-bedded;thin-bedded; lowerlower parpartt massive;massive; ledge~for.mer...... ledge-former* «*«•*••»#•••••*••*•«..*..*••.«.««*.*.« 1515 Cla.yetone;Claystone; lightlight red-bro'Wr1;red-brown; interbeddedinterbedded limestonelL~.. tone; ; cryatalline;crystalline; gray...... gray** •«*»•*•«• 1313 Sandstone;Sandstone; darkdark gragrayy ttoo red-gray;red-gray; interbeddeinterbeddedd thithinn conglomerateconglomerate lenses;lenses; ledge-former*••••••.••*•«••••«••••••••••••ledge-former...... • 1010 CoveredCovered slope;slope; redred,, graygray,, anandd purplpurplee float...... float*2 200 CoveredCovered alope...... slope*•.*•»••••.«•••••••»«••*•*•*••••••••••*.••• 4141

TotalTotal e:x;posedexposed GannettGannett group...... group*. ... •••••••••** 410410 FigurFiguree 1.. VieVieww eastward,, jusjustt southsouth ooff ththee UppeUpperr Narrows, showinshowingg :learBear Rive?iverr formationformation overlyinoverlyingg GannetGannettt groupgroup.. 14

BeaBearr l!ll!!River formationfo"..tion.* Hayde~onn (1874(1874)) name_ d ththoe BeaBoarr RiveRiTerr fonnationformation frofromm exposureupoaU1"'I1s nean.arr BeaBearr RiveRiverr CityCity,, on ththee UnioUnion PacifiPacilicc ShorShortt linLinee Rail­Rail­ roadroad,, iinn southweslouthweatt WyomingWyom1.ng . BeaBearr RiveRiverr CitCityy no longelongerr existsex1.lllta.. ThThee typetype

••sectioction n 1,is a shorahortt distancd1atancee southeasloutheastt ooff RV&nllton.Evanston.

ThThee BBeaear RiverRiver formatioformationn consistcone1atas ofof interbeddeinterbeddedd blacblackk carbocarbonaceounaceouss shale.hal.. s andand g_gray ttoo g_gray-brow-brownn crystallinocrystalline limestonesU-tonoo.. ItIt 10is vervoryy foool1-fossil- iferousiteroua.. TThhee gastropogutropodd anandd pelecypopelecypodd faunfaunaa otof tht hee BeaBlar RiveR1 ver stratstrataa hashas beeboonn thoroughlthoroughlyy studieotudiedd bbyy WhitWhitoe (1895(1895 )) anandd leYonn (1951(1951,, 11952a952&,, 1954).1954).

ThlThe agagee ootf ththee BeaBearr RiveRiverr formatioformationn 1,is a• controversiacontroversiall lsubjectubject..

CobbaCobbann andand a.Reesido.id.e (1951(1951)) correlatecorrelate ththoe .lapeAspen .haloshale witnthh thothe lbvryMowry oshalhalee o!of MlntanaMontana on tthhee basib.. ia s ofof GGastropliteytroplitys andand NeogastropliteNeos utroplitus occurrences,occurrences, assigninUI1gn.1ngg themthem toto ththee uppeupperr Lowerr CretaceousCretaceous (A.lbian).(Albian)• ThThee AaAspepenn overUoverlie•• s ththee BBeaear RiverRiver formationformation iinn losouthwesuthveett WyomingWyoming.. TheThe correlatcorrelatioionn byby CobbanCobban andand RIIuldeReeside 'WOuldwould thereforetherefore placeplace thethe BeBeaa r R1Rive verr inin thethe uppeupperr Lowelowerr Cre­Cre­ tacooustaceous. YonYen (1(1952a952a,, 1954)1954) pointpointes outout thatthat ththoe _Aspe,"penn andand lbvryMowry areare dadatetedd

AlbianAlbian on thethe basib.. 1e s ofof correlationcorrelation withwith thethe PeacePeace RiverRiver formationformation ofof west­west­ emern Canada.Canada. TheThe P.acePeace R1Rive verr haahas beenbeen ulignedassigned toto thethe AlbianAlbian throthrougughh cor­cor­

Natiorelationn vithwith a esinglinglee epeeieespecies otof GGastropliteutropUtus toundfound inin thethe GGaulaultt elqclay atat

]l'olkatoneFolkstone, EngEnglandland . YenYen notesnotes thatthat tthhee GaultGault clayclay eocontainnta1nas lowlowerr UpperUpper

CretaeeouaCretaceous (Cenomanian)(Cenomanian) .peciea,species, andand that thethe ttypypee llbianAlbian otof FranceFrance coconn­­ tainatains no GGastroplitesaptroPl1tea..

8tStudieud1.. s otof trMh-wterfresh-water ggastropodutropodas otof thethe BearBear RiverRiver tonnation,formation, to­to­ ggetheetherr withwith thethe aboTeabove mentionedmentioned obeervatioobservationsna , ledled YenYen toto thethe eoconclusioncluaionn thatthat thethe BeBeaarr RiverRiver tormationformation isis otof CenomanianCenomanian age.age. l'15

YenYen' fSs evidenceevidence appearsappears moremore convincingconvincing thanthan thatthat ofof CobbanCobban andand P.ee­Ree­

side,side, andand thethe WTiterwriter herehere acceptsaccepts thethe CenomanianCenomanian ageage forfor thethe BearBear RiverRiver

formation.formation.

DepositionalDepositional environmentenvironment ofof thethe BearBear RiverRiver strata.strata appearsappears toto havehave

beenbeen shallow,shallow* freshfresh toto brackishbrackish water,water, inin a sub-tropicalsub-tropical climate,climate.

BearBear RiverRiver depositsdeposits representrepresent deep,deep, locallocal basinbasin developmentdevelopment dur.Lngduring

mid-Cretaceousmid-Cretaceous timetime inin southwestsouthwest WyOilJ.ng.Wyoning. TheThe fo:rmationformation hashas limitedlimited lat­lat­

eraleral extent:extent: fromfrom HilliardHilliard F4t,Flat, tr/yomingWyoming onon thethe southsouth toto southeastsoutheast IdahoIdaho

on thethe north,north, andand fromfrom thethe Wl~mingWyoming - UtahUtah boundaryboundary onon thethe westwest toto SneiderSneider

Basin,Basin, WyomingWyoming.. BeaBearr RiveRiverr stratastrata attainattain a maximummaximum thicknessthickness ofof 5,8005,800

feetfeet inin centralcentral Uinta.Uinta eo...mtyCounty (Burger,(Burger, 1955).1955). ApproximatelyApproximately 750750 teetfeet ofof

BeaBearr RiveRiverr bedbedss werweree measuremeasuredd bby-y ththee lITiter,writer, nortnorthh ooff Evanston.Evanston.

FresFreshh watewaterr mollusklTlOlluakas anandd planplantt material:::-.aterialss werveree collectecollectedd frofromm fourfour

BeaBearr RiveRiverr exposureexposuress nortnorthh ooff EvanstonEV&n8ton.. IdentificationIdentificationss werweree madmadee bbyy thethe writerwriter..

SampleBa~,pledd localitie.:localities:

11.. ShelShelll HolloHolloww iinn sectiosectionn 33,, TT.. 1166 N.N.,, RR.. 121200 WW.•• .

22.. ApproximatelApproximatelyy J~ milmilee sout8014,hh ooff UppeUpperr HarrowsNarrows,, aatt basbasee ooff

sectionsection,, iinn sectiosectionn 44,, TT.. 1177 M.N.,, RR.. 121200 wW.•• .

3J.. West-facinWest-facingg slopslopee ooff NarrowNarrowss Kill:Hill,, iinn sectiosectionn 3232,, TT.. 1168 N.N.,,

RR.« 121200 w¥.•• .

44.. MoutMouthh ooff LoweLowerr NarrowsNarrow,, alonalongg roaroadd cutcut,, iinn sectiosectionn 2929,, T ...

11$8 N.N.,, RR.. 121200 W.w•• . 1616

CollectionsCollections included:included;

GutGastropoda ropoda::

fy"rgyliferaFyrgulifera humerosahumerosa (Meek)(Msek)

fyrguilleraPyrgulifera st§11tonistantpni WhiteWhite

Pyrgulif'eraPyrgulifera ap.sp.

PachychiloidesPachychiloides cleburnicleburni (White)(White)

P§c~ychiloidesPachychiloides ap.sp.

Iei:oplacodesUoplacodes stacheistachei inrIatusinflatus YenTen

LioplacodesLioplacodes stacheistachei (White)(White)

UopllcodesUoplacodes ap.sp.

9§lll.E!lo9Campeloma sp.sp.

ZaptychiusZaptychius paldemannihaldemanni (White)(White)

Phya§%YSfr ap.sp.

PelecypodaPelecypoda::

CorbicullCorbicula durkeeidurkeei (Meek)(Meek)

CorbulaCorbula pyriformipYriformiss MeekMeek

CorbulCorbBl:aa asp p..

~Undo belliplicatubelliplicatuas l1eekMeek

Yn!2Unio Yestustuvestustuss MeekMeek -UniUnioo ap.sp. PlantPlant materialmaterialss werweree fragmentalfragmental anandd poorlpoorlyy preservedpreserved,, andand couldcould nonott bbee identifieidentifiedd bbyy ththee writer.writer.

ThThee followinfollowingg sectiosectionn wawass measuremeasured.d approximatelapproximatelyy 4~ milmilee northnorth ooff ththee entrancentrancee ttoo ththee UppeUpperr MarrowsNarrows,, iinn sectiosectionn 3232,, TT.. I18B N.,N., iR.i 121200 W.,W.f 1717

EvanstonEvanston formationformation BearBear HiRive verr formationformation Feet

CoveredCovered slope;slope; blacblackk soilsoil~, ..a fereww fresh-fresh­ waterwater gastropodgastropodss iinn floatfloat*...... ••••••••••••••••••••••••. •••••••••• limestoneLimestone,, crystalline;crystalline; blacblackk toto darkdark gray,gray, weatherweatherss lightlight gray;gray; abun­abun­ dantdant fresh-waterfresh-water pelecypodspelecypods,, whiohwhich weatherweather ttoo a chalk-whitechalk-white...«.«....«*•..«.*.«.««* •••••••••••••••••••••••••. 11 Shale;Shale; blackblack,, carbonaceous;carbonaceous; slope-formerslope-former ••••••••••••••.... 51 Iirnestone,limestone, cr.;rstalline;crystalline; blacblackk toto darkdark gray;gray; veryvery fossiliferous,fossiliferous, contain-contain­ iningg fresh-waterfresh-water pelecypodpelecypodss andand gastropods,gastropods, whicwhichh weatherweather Whitewhite...... ••••••••••••••••••. 4 Shale;Shale; blackblack,, carbonaceouscarbonaceous;; slope-formerslope-former...... •••••••••••••• . 22 limestoneUmestone,, crystalline0 rye talline;; blacblackk toto darkdark gray;gray; containscontains pelecypodpelecypodss 8.Tldand

gastropods,gastropods, whicwhichh weatheweatherr white .•••••••••••••••••• ...... Q 7 Shale;Shale; blackblack,, carbonaceous;carbonaceous; slope-fornJ.erslope-former...... 31 Shale;Shale; blackblack,, carbonaceous;carbonaceous; containscontains small,smll, angulas,11.gularr fragmentfragmentss ofof purplepurple,, ironiron oxideoxide stainedstained limestone;limestone; slope-formerslope-former.»••.•••••••••••••••••••••••••• . ...•••.*••«•••• 29 Limestone;limestone; crystalline;crystalline; thin-bedded;thin-bedded; blackblack,, weatherweatherss fray;gray; veryvery fossiliferousfoss iliferous...... *...«... ••••••••••••••••••••••••••••••••••••. 20 Shale;Shale; blackblack,, ca.rbonaceous;carbonaceous; slope-former.slop~-form.er ••••••••••••••. 10 CoveredCovered slopeslope•••••••»•••••.••••••»•••••••••»••••••.•• •••••••••••••••••••••••••••••••••••••••••• 10 CoveredCovered slope;slope; float.float oontainscontains black,black, carbonaceouscarbonaceous shale,shale, andand somesome fresh-waterfresh-water gastropodsgastropods andand pelecypods••••••pelecypods •••••••••••••••••••••••••••••••••••••••• 133 UJ'Il..estone;Limestone; crystalline;crystalline; thin-bedded;thin-bedded; ververyy fossiliferous;fossiliferous; grtrqgray toto gray-browngr!\,y-browu;; weatherwatherss intointo rectangular,rectangular, blockyblocky fragmentsfragments..... ••••••••••••••••••••. 11 CovCoverede red sI.opeslope...... 22 Limestone;Limestone; crystalline;crystalline; thin-bedded;thin-bedded; ververyy fossiliferous;fossiliferous; gragrayy toto gra.Y'-brown,gray-brown, weatherweatherss intointo blockyblocky fragments...... fragments ••••••••••••••••••••••••••••••••••••••••. 9 Shale;Shale; black,black, carbonaceous;carbonaceous; slope-formerslope-former. ••••••••••••••. •• 17 Limestone;limestone; crystallinecrystalline;; containscontains white,white, calcitecalcite lentils;lentils; darkdark graygray ttoo blue-blue- gray-,gray, weatherweatherss gray-brown;gray-brown; slightlyslightly fossiliferousfossiliferous...... ••••••••••••••••••••••••••••••••••••. 5 Shale;Shale: bla.ck,black, ca.rbonaceous;carbonaceous; slope-formerslope-former. ••••••••••••••• • • 5 I18B

LimestoneI.i.meltone*; crystallineoryatalline;; containeontainas lrilit.white,, caleitcalcitee lentils;; tthin-beddedhin-bedded;; fossiliferous!ossiliferous;; dardarkk gray ••gray*I• •••••••••• ~ ...... 18B ShaleShale;; blackblack,, carbonaceouscarbonaceous;; .lslope-former..2ope-former •• ft ...... 299 LimestoneLimestone;; crystallinecryatall1ne;; thin-thin-beddedbedded;; ververyy fossiliferousfoaliureroua;; ggray-brown..rtiY-brown...... 5 ShaleShall;; blackblack,, carbonaceouscarbonaceoua;; slope-former.... lope-former...... 8080 LimestoneL1meatonej; crystallinecryatallin.;; thin-thin-beddedbedded;; fossiliferousfoaliliferous;; blackk toto dardarkk gray...... grq •••• "...... :33 ShaleShale;; blackblack,, carbonaceouscarbonaceou.a;; slope-forme.Iopa-formerr ...... ••••••• 9 LimestoneLim•• tone ;; thin-beddedthin-bedded;; fOIl.iliferousfossiliferous; ggray—brown...... rq-brown...... 2 limestoneLimestone,, shalyI haly;; blackblack,, weather_athenss grgrayq;; weatherweatherss intintoo small,small, flat,, Iplin-splin­

teterryy fragmenttragIQeIltas «....*•**««..***..*•••*.«.•••••«.«...... II ...... • .. 19 LimestoneL1meetone;; gray-browngrq-brown,, weatherweathe:zws brow;brown; veryvery fossiliferous*•»#•*«**••#.«««#...*...**.*««toelliliferoua ...... # 10 GovCoverede red slslope...... ope ...... 1414 Li.meLimestoneatone;; crystallinecI)"IItalline;; ververyy fc».il­fossil­ iferousileroue;; dardarkk brovnbrown ttoo purple,purple, weatherweathen* lilighghtt browbrolClln ttoo blueblue­- grgrayq.; waatweatherhens intintoo angularangular fr~tfragments&...... • ...... 16 Shale;Shale; carbonaceou.carbonaceous;; blackk t o bbluel ue­- bblacklack;; weatherwathens intointo finfinea,, splinterapllntGr,yy fragments•••...... #...... *....«.....f ragments...... 110055

TotalTotal BearBear RiverRiver formation.....t onnat1on...... **...... 749749

UnUnconforMityconj'ormity*. It.it ~majoo r hi.tUIIhiatus exist~xiet.s utltwuenbetween thuthe BeaBearr RLverRiver fonnatformation,i(ln,, (Ifof E'earlI,rlyy lorLat.tE'e CCretaceoureteceo'USs age,age, andand tthhee oveoverlyinJ:"lyingg t'VEvanstoanatonn tonnatioformationn,, of lateatlatest CCretaceoureti!.ceou.s ((BanianDanian)) &ndand PalPaieoceneocenee age (aee(see figurefigure 22)).. ThisThis 1nterrrU.interval I"6prearepresententas anan .ts.rabsenc~ ce orof astrati'rataa nortnorthh ofof

ETanatEvanstoncn, lrd'..1cb,which, tc.to ttthle eueastt a fellfew miles inin centrnl.central UUintint a County,County,

!Demeasureuure.s ~pproJdmatel¥approximately 14,14,000000 tcst.feet* FFouourr fo:n:at1onsformations havhavee beenbeen mapJ*lmapped inin thisthis int.I"Iinterva&ll inin adadjacenj acentt aai-eareu s toto tthhee eastt andand north.north.

DDescription"criptior..es md.and thithicknesse('knes!es areare ta..take'

(195(1955)5),, andand NNixoixonn (1(1955)955 ).. liT. lib, •

Figure 2 .. View northward from Wyoming ":"Ghway 89 at the southern boundary of the area, showing Evanston for-nation resting on Bear River beds. 2020

AdavilleAdaville formation----yellow,formation yellow, gray,gray, andand blackblack carbonaceouscarbonaceous

clay,clay, irregularlyirregularly beddedbedded brownbrown andand yellowyellow sandstone,sandstone, withwith

nwnerousnumerous coalcoal beds;beds; upperupper MontananMontanan andand lowerlower DanianDanian age;age;

4,0004,000 toto 5,0005,000 feetfeet thick.thick.

HilliardMilliard format1on-----grayformation gray toto blackblack sandysandy shales ,J shalyshaly sand-sand­

stone,stone, andand severalseveral discontinuousdiscontinuous whitewhite sandstonesandstone lenses;lenses;

upperupper ColoradoanColoradoan andand lowerlower l.'1ontananMontanan age;age; 5,5005,500 toto 6,0006,000

feetfeet thick.thick.

FrontierFrontier formation-----aandstones,formation sandstones, siltstones,siltstones, anandd conglomeraticconglomeratic

sandstonessandstones interbeddedinterbedded withwith black,black, gray,gray, anandd yelloyelloww s~lalessaales

andand mudstones,mudstones, withwith minorminor amountsamounts ofof bentonitebentonite anandd porcel-porcel-

lanitelanite nearnear thethe base;base; twtwoo maimainn coalcoal zones;zones; ColoradoaColoradoann age;age;

2,002,0000 feetfeet thick.thick*

AspeAspenn formatioformation-----darkn dark colorecoloredd sandsandyy shaleshaless anandd lighlightt coloredcolored

porcellanitporcellanitee bedsbeds,, composecomposedd chieflchieflyy ooff alterealteredd volcanicvolcanic

tufftuff;; CenomaniaCenomaniann agagee (lowe(lowerr Coloradoan)Coloradoan);; 1,801,8000 feefeett thick.thick.

Coloradoan-MbntanaColora(ioan-1\fonta.nann boundarboundAU'y problemproblem.. ThThee placemenplacementt ooff ththee Coloradoan­Coloradoan-

MontanaMontanann boundarboundaryy iinn ththee stratstrataa ooff southwestersouthwesternn WyominWyomingg iiss a mattematterr ooff dis-dis­ putepute.. AccordinAccordingg ttoo BurgeBurgerr (1955);(1955)?

"Th"Thee boundarboundaryy lieliess somewher80meldleree betweebetweenn ththee middlmiddlee ooff thethe MilliarHilliardd formatioformationn anandd ththee middlmiddlee ooff ththee overlyinoverlyingg Ada­Ada­ villvillee formationformation.. ThThee basbasee ooff ththee MontanaMontanann iiss placeplacedd atat ththee firsfirstt appearancappearancee ooff DesmoscaphiteDesmoscaphitess bassleribassleri,. butbut thesthesee havhavee nonott beebeenn reportereportedd iinn southwestersouthwesternn Wyoming.11t*

VeatcVeatchh (1907(1907)) reportereportedd basabasall NiobraraNiobrare.,, oorr uppeupperr BentoBentonn (upper(upper

ColoradoColorado)) fossilfossi18s iinn ththee MilliarHilliarod formationformation,, 3,803,8000 feefeett abovabovee ththee baae.base. 2121

HeHe assignedassigned thethe lowerlower .3,9003,900 feetfeet ofof thethe HilliardMilliard ttoo ththee Coloradoan,Coloradoan,

andand ththee upperupper .3,0003,000 feefeett toto thethe Montanan.Montanan.

CobbanCobban andand ReesideReeside (1952)(1952) foundfound NiobrarNiobraraa fossilsfossils neanearr thethe

toptop ofof thethe HilliardMilliard formatioformationn andand inin ththee lowestlowest fewfew hundrehundredd feetfeet ofof thethe AdavilleAdaville formation.formation*

GaugerGanger (1952)(1952) studiedstudied thethe microfossilsmicrofossils ofof ththee HilliarHilliardd for-for­ mation,mation, andand drewdrew thethe followingfollowing conclusion:conclusions

"The"The lowerlower 950(?)950(?) feetfeet isis Benton.Benton. TheThe middlemiddle .350(1)350(?) feetfeet isis NiobraraNiobrara.* TheThe upperupper 2,8622,862 feetfeet isis definitelYdefinitely Montanan.tt"

SinceSince neitherneither ofof thethe involvedinvolved unitsunits areare presentpresent inin thithiss area,area,

thethe writerwriter cancan makemake nono additionsadditions toto ththee boundaryboundary problem.problem*

TertiaryTertiary systemsystem

EVanstonEvanston formationformation.* TheThe EYanstonEvanston formationformation waswas namenamedd byby

VeatchVeatch (1907)(1907) fromfrom exposuresexposures alongalong thethe easteast sideside ofof ththee BearBear

RiverRiver valley,valley, aboutabout twotwo milesmiles northnorth ofof Evanston,Evanston, Wyoming.Wyoming*

EvanstonEvanston bedsbeds consisconsistt ofof yellow,yellow, gray,gray, andand blackblack claystone,claystone,

siltstone,siltstone, andand shale,shale, andand browbrownn andand whitewhite sandstonesandstone anandd conglo­conglo­

Dlerate,merate, vithwith abundantabundant organicorganic material.material* DiscontinuousDiscontinuous coalcoal seamsseams

areare characteristiccharacteristic ofof thethe formation.formation* OneOne coalcoal bedbed iiss exposedexposed

torfor a shortshort distancedistance northnorth ofof Evanston,Evanston, butbut isis absentabsent inin elqlOS-expos­

uresures northnorth ooff ShellShell Hollow.Hollow* TheThe coalcoal seamsseams areare dirt,.,dirty, loloww gradegrade

bibituminoustuminous •• 2222

AbundancAbundancee ootf clacl.ar,yy an&D1d carbonaceoucarbonaceouss materialmater1&las iinn ththee ETanstonEvanston formatiofonnationn hah...... s resulteult.d d iinn slumpinslumpingg alon&longg outcropsoutcrope.. Ind1rlduolIndividual bedbedss araree characteristicallcharacteristicallyy lenticulalenticularr anandd discontinuousdiacontinuoUl.. NNoo bedabeds werweree continuoucontinuouas enougenoughh ttoo servaerYee a..s referencreterencee hor1sona.horizons.

EvanstoEvanstonn exposuree.x;poaurus havhavee beebeenn mappemappedd throughouthroughoutt ththee FOFossiI.l1l

BasinBuiD.. OutsidOutsid.e thithiss areaarea,, ththee EvanstoEvanstonn formatioformationn iiss nonott reprerepre-­ sented•• nted.. EvanstoEvanstonn stratstrataa represenreprelent a localooall basib.. inn ootf depoeltlon,deposition, ootf moderatmoderatee depth.depth.

BurgeBurgerr (1955(1955)) suggestouggootos thathatt ththee EvanstoEvanotonn formatiofomaUonn mamayy bebe equivalenequivalentt ttoo ththee uppeupperr portioportionn ootf ththee NortNorthh HorHomn formation,formation, ththoe loweloloorr portioportionn ooff ththee FlagstafFlagotatff formationfonnation,, anandd possiblpoooiblJ"y thothe

CurranCUrrantt CreeCreekk formatiotonnatlonn ooff ththee westerweternn UintUintaa MountainsMounta:1na,, Utah.Utah.

TheThe EvanstoEvan.tonn formatiotonaationn restrut.s unconformableuncontormabl¥* upouJX)nn ththee BearBear

RiveRiTerr formatiotontationn nortnorthh ootf EvanstonEVlJlIIton,, WyomingWyoming.. IInn ththee SagSagee andand

KemmererKemmerer,, Wyoming,Wyoming, areaarea ththee EvanstoEvanstonn restrestss unconformablunconionuablyy uponupon thothe AdavillAdavillee andand oldorolder fo_tionoformations (Trac(TracTy anandd OrielOriel,, 1951959)9) ..

AA. problomproblem oxlotoexists regardingregarding ththoe agagee ooff ththoe EvanotonEvanston fomationformation..

A.ccordingAccording ttoo TracTTracy andand OrielOriel (1959).(1959)?

"Vertebrate"Vertebrate remainroma1nos foundfound bbTy ththoe writewriterr 265265 t.etfeet aboveabove thethe basbaae otof thethe unitunit inin ththee •sectio• ctionn alongalong thethe southamsouthern boundaryboundary otof thethe Kelllll8rerKemmerer QlwlrongleQuadrangle inincludcludee a partpart ofof thethe jajaww ofof aa TriceratopoTricerateps cf.cf. 1.T. fl.abell&tuoflabellatus IIaroh,Marsh, indiindi­­

o.tinacating probablJrprobably Lance,Lance, oorr l&t"tlatest Cretaceoua,Cretaceous9 agagee (G.(G. E. levi.,Lewis, writtewrittenn collllllWl1cation,communication, 1958).1958). 4A vertebratevertebrate fauna foundfound byby C.C. L*. GaBinGazin 250250 toto 300300 f.etfeet belowbelow thethe totopp ofof thethe unitunit inin thethe northweetnorthwest comercorner ofof Sec.Sec. 14,14, T. 2121 NN..,, R.R. ll7117 WW.. ,, includesincludes Plesiad.tP1.Plesiadapis cf.cf. f.P. fod1natuafodinatus Jepsen,Jepsen, 2233

PhenacoduPhenacoduas sp.ap e,, anandd otheotherr genergeneraa indicativindicativee atof TiffaniaT1!taniann oorr earlearl,yy latlatee PaleocenPaleocenee agagee (Gazin(Gu1n,, 1951956a6a,, pp.. 708)708 ).. PlanPlantt remainroma1nas frotromm ththee totopp anandd bottbottoOlllm oatf tht hee formatioformationn araree iinn accoracoordd wit~thh thestheaee de­­ terminationterm1natloIllls (R( R. IVW.. BrownBrolm,, writtewrittenn coImIlllllica-communica­ tiontion,, 19551955,, 19581958)) anandd indicatindicatee thathatt ththee Creta­Creta­ ceoue-ceous -PaleocenPaleocenee boundarboundaryy mamayy li11ee withiwithinn thethe uppeupperr finer-grainetiner-grainedd parpartt ootf ththee tonnation.formation.tt"

McropaleontologicaMicropaleontologicall studiestudiess ootf ththee EvanstoEvanstonn formatioformationn ledled

BarretBarrettt (1953(1953)) ttoo ththee conclusioconc1uaionn thathatt ththee EvanstoEv_tonn i10s entirol,yentirely

Paleocene.Paleocene. BarretBarrettt furtheturtherr concludeconclude.s thathatt ththee CretaceousCretaceous-Tertiar- Tertiaryy boundar:rboundary 10is includeincludedd iinn ththee majomajorr hiatuhiatuss betweebet""enn ththee EvanstoEv_tonn andand

SBeaear River tormations.formations. ThesThea"e conclusionconclusionss araree nonott iinn accoraccordd withwith thothos.. e otof TraCTracyT anandd OrieOriell (1(1959)959).*

ThisThis writerwriter measuremeasuredd 1,33l,J)O0 feeteett oatf EvanstoEvanstonn stratstrataa nneaearr

SShelholll Hollow.Hollow. BarretBarrettt measuremouurodd 737322 feeteett ootf EvanstoEvanstonn aapproximatelpproxlmatel,yy one-haltone-half milmil.e 80uthsouth oatf thithiss writer'writer'.s measuremeasuredd sectionaeetion.. BarrettBarrett indicindicateatedd a smalsmalll parpartt ooff ththee basabasall EvanstoEvanstonn strats trataa wawass unexposed.unexposed.

Th.The additionaladditional stratastrata ..assignesigned d ttoo ththee EvanstoEvanatonn bbyy thethe writewriterr werewere mappedmapped ..as BBeaearr RivRiveerr formatioformationn bbyy BBarrettarrett.. ThereThere i.eis doubdoubtt aboutabout thethe exactexact poSitionposition ootf ththee contact,contact, duedue ttoo alluvialalluvial covecoverr ..

TheThe lowelower .315315 teetfeet otof ththee writer'swriter's measuremeasuredd EvanatonEvanston tor-for­ matioomation maymay actuallyactually bebe BeaBearr RiveRiverr ststratarata.. Thes.These bedbedas araree l1.me­lime­ ltonee,stones, llghtlight ggrarqy ttoo brown and.and red-brownred- brown,, massivmua1Tee toto asugarug&ryy textUred.textured. NoNo to.a1Iafossils warewere toundfound inin thethesaee .limelimestones.tonse.. TheThe bedsbeds inin quest10nquestion cocontrasntrutt withwith thethe uppeupperr limestoneslimestones otof ththee knownknown BearBear

RRivel:Y8rr tormat10nformation 1nin colocolorr,, texture,texture, andand tosa1lfossil content.content. NoNo breakbreak 24 iiss founfoundd betweebetW8nn ththee basbuee ooff ththee bedb.as iinn questioquestionn anand.d ththee totopp ofof ththee knowknownn EvanstoEvanstonn formation*. SedimentatioSedimentationn appearappearss ttoo havhavee beenbeen continuoucontinuouss throughouthroughoutt ththee lequence.sequence*

ThThee abovabovee featurefeaturess havhavee leledd ththee writewriterr ttoo arbitrarilarbitrarilyy plaplaccee ththee BeaBearr RiveRiverr - EvanstoEvanstonn contaccontactt belobeloww ththee limestonesl iinn questionquestion*.

ThThee writer'writer'ss measuremeaauredd thicknesthicknesss ooff ththee EvanstoEvanstonn formationformation

(1,(1,333300 feetteot)) ii.s inin closclosoe agreement witwithh thosthosee reportereportedd bbTy VeatchVeatch

(absen(aboontt ttoo 1,6001,600 feetteot)) anandd TracTracTy anandd OrieOriell (1,20(1,2000 teet).feet).

IInn vievie.w ooff ththee abovabovee evidenceeridence,, ththee writewriterr iias inclineinclinedd toto agreoagree witwithh thethe proposapropo.all thathatt ththee Cret&ceouaCretaceous-Tertiar-TortiaTTy boundarTboundary li.lies withinwithin ththee EvanstonEvanston formation,formation, probablprobablyy belobeloww ththee .esectioctionn

COTecovereredd iinn BarrettBarrett' 'as studyatudy*. ThiThills relationship,relationship, howeverhowever,, iias con­con­ jecturajecturall duedue toto lackk ootf accurateaccurate ddatinatingg otof ththee lowelowerr portionportion otof thothe EvlInatonEvanston inin thith1.s rlc1n1vicinitytT' *

TheThe ETanstonEvanston formationformation reaterests unconformablyunconformably onon ththee BeaBearr R1Rive verr formationn inin thothe vivicinitc1n1tTy ootf ShollShell Hollow.Hollow* VVariationariationas iinn .trikestrike rangerange fromfrom 3030 toto 4545 degreesdegrees betweebetweenn thethe twtwoo tormationa.formations* DipDips var,rvary allas mumucchh asas 1515 degreedegreess.* TheThe llthologieelithologies ofof thethe twtwoo torma­forma­ tionstions inin th1ethis areaarea areare ver,rvery dias1m1lar.dissimilar* BearBear RiverRiver llthologylithology i.is euilyeasily recognised,recognized, conaiaconsistintingg ofof darkdark graygray toto black,black, carbon­carbon­ aceous,aceous, h1&hlfhighly lofossiliferoussilitereuss shale.shales andand limestonelimestones..* TheThe over­over­ lyinglying EvanstonEvanston IIstrattrataa areare ccomposeom.poeedd otof lightlight graygray toto white,white, brom,brown, andand yellowyellow sandstonell,sandstones, calcareouscalcareous sandstosandstonesnea , andand l.1.meatonelimestonesll,, interbeddedinterbedded withwith vari-coloredvari-colored c1&78.clays* 2;25

BarrettBarrett (1953)(1953) describesdescribes ththee depositionaldepositional environmentenvironment ooff thethe

EvanstonEvanston a8as beingbeing a moismoistt andand coolcool climate,climate, withwith abundantabundant freah-fresh­

waterwater at8tream reamss andand ponds.ponds.

TheThe EvanstonEvanston formationformation iiss unconformablunconfonnably'y overlainoverlain bbyy thethe

WasatchWasatch fomationformation inin thethe reportreport areaarea (see(see figurefigure .3).3).

PlantPlant remainsremains areare abundantabundant inin ththee EvanstonEvanston formation,formation, butbut specimensspecimens collectedcollected _rewere totooo poorlpoorlyy preeervedpreserved toto bbee identifiedidentified byby thethe writer.writer.

TheThe followingfollowing sectionsection wawass measuremeasuredd aboutabout i£ milemile easteast ooff thethe

junctiojunctionn ofof WyomingWyoming HighwayHighway 8989 andand thethe unimproveunimprovedd roadroad travereingtraversing

thethe easteast sideside ofof ththee BearBear RiverRiver vallevalleyy northnorth ofof Al.myAlmy Station,Station, inin sectionsection 11,11, T.T. 1616 N.,N., R.R. 120120 w.,W.s

W"atchWasatch formationformation EvanstonEvanston formationformation Feet

CoveredCovered slope;slope; yellow-brow,yellow-brown, pink,pink, andand grAYgray claystoneclaystone float...... float.••••••••».«••• 75 Siltstone;Siltstone; thin-bedded;thin-bedded; lightlight grAY,gray, witwithh prominentprominent ironiron atains;stains; weatherweatherss intointo sharp,sharp, angularangular fragments...... fragments •••••• ••••••••••••• J Claystone,Claystone, shaly;shaly; thinthin lenseslenses ofof lightlight graygray sandstone;sandstone; slightlyslightly carbonaceoua;carbonaceousj darkdark graygray toto gray-brown,gray-brown, weathersweathers lightlight gray;gray; slopeslope former...... former...... •.»•••.•••••.••.. 29 Siltstone;Siltstone; thin-bedded;thin-bedded; darkdark brownbrown toto red-brcnm,red-brown, weathersweathers purple,purple, maroon,maroon, toto rustrust color,color, withwith pronouncedpronounced iiro ronn oxidoxidee sta.i.ns,stains; weatheraweathers intointo smal.l,small, angularangular fragments...... fragments. •• • • 3 2626

Sandstone,Sandstone, mediumediumm grainedgrained;; thin­thin- beddedbedded toto platyplaty;; slightslight cross­cross- beddingbedding;; tossilfossil planplantt material;material; brownbrown ttoo yellow-brownyellow-brown,, salt-salt- and-pepperand-pepper appearance...... appearance • 1111 SiltstoneSiltstone.; slightlyslightly carbonaceous;carbonaceous; darkdark gragrayy ttoo maroonmaroon;; slope-slope- fornterformer ••••••••••••••••••••••••••••• e.....• ...... • 3737 Sandstone;Sandstone; fine-grainedtine-grained;; thin­thin- beddedbedded;; yello~orange,yellow-orange, weatherweatherss maroomaroonn ttoo rust...... rust...... • 44 Coal;Coal; highhigh proportioproportionn otof siltsilt andand claclayy (very(very dirty);dirty); containscontains thinthin,, yelloyelloww mineralizedmineralized bandsbands (appearance(appearance ofof somesome uraniumuranium mineral)mineral);; slope-former...... slope-former 2929 Sandstone,Sandstone, silty;silty; fine-grainedtine-grained;; thin­thin- beddedbedded;; dardarkk browbI"Olmn andand red-brownred-brown toto yellow-brownyellow-brown.; wathersweathers a deepdeep rusrustt ttoo maroomaroonn color...... color •«»•••••• * J3 Sandstone,Sandstone, silty;silty; fine-grained;fine-grained; thin­thin- beddebeddedd toto platy;platy; lightlight gragrayy toto lightlight b~brown •••••••••••••••••••••••••••••••••••••••• ••• 3 Claystone,Claystone, silty;silty; slightlyslightly carbon­carbon­ aceous;aceous; darkdark graygray,, weathersweathers lightlight gray;gray; slope-former.••«••••...••••••.••..«.slope-former...... 5 Siltstone;Siltstone; veryvery dardarkk gray-brown;gray-brown; ironiron stainedstained Burfaces,surfaces, darkdark rusrustt ttoo maroomaroonn andand purple...... purple 2 Cla;rBtoneClaystone andand siltstone;siltstone; dardarkk gray;gray; weatherweatherss lightlight graygray;; slope-former...... slope-former •• 3535 sandstone;Sandstone; tine-grained;fine-grained; thick-bedded;thick-bedded; yellow-brownyellow-brow;; weathersweathers orange-orange- rustrust toto maroomaroonn andand purplepurple...... •••*•• 44 ClaystoneClaystone andand siltstone;siltstone; darc1.arkk gray,gray, weathersweathers lightlight grayg~;; slope-former...... slope-former.•••• 2828 Shale,Shale, silty;silty; thin-beddedthin-bedded;; black,black, weatherweatherss blue-grablue-gray...... y J3 Coal,Coal, shaly,shaly, siltysilty (poo(poorr grade);grade); formsforms blacblackk andand gragrSJ-y mottledmottled slope...... slope 2828 Sandstone;Sandstone; fine-grainedfine-grained;; thin-bedded;thin-bedded; W8athensweathers intointo largelarge,, angularangular frag­frag­ mentsments;; darkdark rust-rerust-redd ttoo maroon,maroon, weatherweatherss maroomaroonn ttoo purple,purple, highlyhighly stainedstained witwithh ironiron oxide...... oxide • •»•••••• 22 2277

ClqstonezClaystone; gray-brown;gray-brown; weatherweatherss lightlight gragr~y ttoo whitewhite;; slope-formeslope-formerr •••••••••••••••••••••• 28 Sandstone;Sandstone; fine-grainedfine-grained;; thin-bedded;thin-bedded; weatherweatherss intintoo large,large, angularangular fragments;fragments; darkdark rust-rerust-redd toto maroonmaroon,, weatherweatherss maroomaroonn ttoo pur-pur­ pleple,, highlhighlyy stainestainedd witwithh ironiron oxidoxide...... e 44 Claystone;Claystone; darkdark graygray,, weatherweatherss lightlight gragrayy toto whiteWhite;; slope-former...... slope-former. 3838 CoveredCovered slope...... slope. •»••••« ...... 8282 Sandstonesandstone;; verver:!y fine-grained,fine-grained, massive;massive; thin-beddedthin-bedded;; calcareouscalcareous;; lightlight gray...... gr~...... 11 CoversdCovered .lope...... slope.•* *•* 11 Sandstone.Sandstone; ververyy fine-grainedtine-grained,, massive;massive; thin-beddedthin-bedded;; calcareouscalcareous;; lightlight graf...... gray ..... 66 CoveredCovered slope.•••••••••••••••••••••••.••«Bl~p~...... • •••« 2020 Conglomerate;Conglomerate; thin-beddedthin-bedded;; quartsitequartzite andand ch_rt.chert pebblepebbless J~ inchinch toto 1 inchinch inin diameter,diameter, slightlyslightly rounderoundedd toto sub-angularsub-angular;; poorlpoorlyy cemented;cemented; gray-browngray-brown toto yellows-brownyellow-brown,, withwith ironiron oxidoxidee stains...... stains..*«.«.«•..•«••«*««.«•...••«••«* 1717 Sandlltone;Sandstone; medium-grainedmedium-grained,, massive;massive; thick-bedded;thick-bedded; lighlightt grag~y ttoo .nite,white, witwithh prominenprominentt yelloyelloww ttoo yellow-yellow- greengreen iroironn oxideoxide sta1na...... stains.**.••«••••« S8 Sandatone;Sandstone; coarse-grainedcoarse-grained;; laminated;laminated; pinkpink toto browbro~...... n • • 22 CovereCoveredd slope...... slope...... 33 Conglomerate;Conglomerate; thin-beddedthin-bedded;; quartsitequartzite pebblespebbles 1 incinchh toto 3 incheinchess inin diameterdiameter,, slightlslightlyy rounded;rounded; poorlypoorly cemented;cemented; browbrownn ttoo red-red- brownbrown...... * • ••••••••••..•••*• • •• 1010 Claystone;Claystone; graygray;; slope-fonner...... slope-former. •*.*• 2323 Conglomerate;Conglomerate; thin-beddedthin-bedded;; quartzitequartzite pebblespebbles t£ inchinch toto 1 incinchh inin dia.rneter;diameter; dardarkk brownbrown,, witwithh ironiron oxideoxide stains...... stains.•••* 1313 Sandstone;Sandstone; fine-grainedfine-grained;; lightlight graygray toto whitewhite,, witwithh ironiron oxidoxidee Btains;stains; slope-former...... slope-former * *•••••*•• 5 Sandstone;Sandstone; coarse-grained;coarse-grained; slightlyslightly conglomeratic;conglomeratic; yellow-browyellow-brownn toto red-brownred-brown;; slope-formerslope-former*....«••*••••*.••.••••••••••••••••••••••••••••••••• • 14 28

CoveredCovered slope;slope; sandstonesandstone andand claystoneclaystone float...... float. 3030 ClaystoneClaystone andand sandstone;sandstone; lightlight graygray toto white;white; slope-former...... slope-former.• • • • 5353 CoveredCovered slope...... slope.• •••••* 8989 Quaternar,rQuaternary alluvium...... alluvium • 119119 CoveredCovered slope...... slope •• 1111 Sandstone;Sandstone; fine-grained;fine-grained; thin-bedded;thin-bedded; yellow-brownyellow-brown toto gray-brown,gray-brown, withwith bandsbands ofof ironiron oxideoxide stains;stains; salt-salt- and-pepperand-pepper appearance...... appearance.» 5 Sandstone;Sandstone; fine-grained;fine-grained; sugar,ysugary tex­tex­ tured;tured; thick-bedded;thick-bedded; lightlight gray,gray, withwith yellowyellow bands;bands; becomesbecomes moremore yellowyellow ttoo yellow-brown,yellow-brown, withwith lightlight graygray bandsbands,, nearnear thethe top...... top... 1616 Sandstone;Sandstone; fine-grained;fine-grained; thick-bedded;thick-bedded; sugar,ysugary texture;texture; lightlight graygray ttoo white...... white...... 5 Sandstone;Sandstone; medium-grained;medium-grained; thin-bedded;thin-bedded; gray,gray, sa1t-and-peppersalt-and-pepper appearance,appearance, wathersweathers yellow-brown,yellow-brown, withwith graygray andand yellow-browyellow-brownn bands.•••••••bands...... • ••••• 22 Claystone,Claystone, sandy;sandy; g~;gray; slope-former...... slope-former 33 Sandstone;Sandstone; medium-grained;medium-grained; thin-bedded;thin-bedded; lightlight brownbrown toto yel1o~brown...... yellow-brown • 22 CoveredCovered elope...... slope • • * 2222 Sandstone;Sandstone; fine-grained;fine-grained; thin-bedded;thin-bedded; lightlight graygray toto whitwhite...... e 1414 CoveredCovered slope...... slope • •• *.•••••••••«•• 1919 Sandstone;Sandstone; fine-grained;fine-grained; thin-bedded;thin-bedded; lightlight brownbrown witwithh darkdark browbrownn bands...... bands.•• 33 5andstone;Sandstone; fine-grained.fine-grained; thin-bedded;thin-bedded; slightlyslightly calcareous;calcareous; lightlight gray,gray, withwith ironiron oxideoxide stains...... stains•• 1010 Sandstone;Sandstone; medium-grainedmedi~grained;; thin-bedded;thin-bedded; g~-brown...... gray-brown 3333 Sandstone;Sandstone; fine-grained;fine-grained; thin-bedded;thin-bedded; calcareous,calcareous, withwith calcitecalcite bands;bands; browbrownn ttoo gray-brown...... gray-brown 7 Limestone,limestone, sanely';sandy; oryatalline,crystalline, mals1ve;massive; thin-beddedthin-bedded;; browbrownn toto red-brown;red-brown; weathersweathers intointo large,large, rounderoundedd fragments...... fragments...... 1717 Umeatone;Limestone; suga.rysugary texturetexture;; thin-bedded;thin-bedded; lightlight graygray,, withwith ironiron oxideoxide stains...... stains •••• 4343 Limestone;Limestone; crystallineOrystallinei; brown;brown; frac-frac­ tureturess intointo conchoidalconchoidal,, roundedrounded tragments...... fragments.. • • 22 299

LimestoneLimestone;; crystallineCrywtallin8;; thin-bedded;thin-bedded; dardarkk graygr.;y,, weatherweatherss lighlightt grgrayay...... •••••••• • •• • 51 LimestoneUmeatone,, shalylllha.ly;; sugarsugaryy texture;texture; lighlight gragray...... y ...... 8 Limestoneu.meatone;; sugarsugaryy texturetexture.; tbinthin-- beddedbedded;; grag ~y ttoo lighlightt ggrayr~...... 1188 limestoneLimestone,, shalyahaly;; granulargranular;; gray..gray ...... 1177 CovereCoveredd .lope..slope ...... 11552

TotaTotall EvanstoEvanstonn tor.matlonformation ...... 1,331.3300

WgatchWasatch formationto!lll.\t1on.. HaydeHaydenn (1869(lJl69)) firsti",tt suggesteouggeetedd ththoe n_name

"Wasatc"Wuatchh groupgroup'" fotorr ththee sequencsequencee ooff coarscoarsee elasticsclastica,, ootf EoceneEocene ageage,, iinn ththee southwestersouthwes ternn WyominWyomingg - northeasternortheastemn Utautahh region.. H1aHis typtypee localitlocalityy wawus nonott clearlclearlyy defineddefined,, includinincludingg ththee areareaa fromfrom

Evanston,Evanston, WyominWyo!Zl1.ngg westwarwestwardd intintoo EchoEcho CanyonCanyon,, UtahUtah.. TheThe namn.a.mee i.eis thoughthoughtt ttoo havhavee beebeenn derived.riTed d frotrom.m Wasatcwasatchh Station,Station, southwesaouthweatt otof

Evanston,Evanston, WyomingWyoming..

VeatcVoatchh (1907)(1907) ssubdivideubdividedd thothe groupgroup intintoo threthroee mambo""members :

AlmAlmy"y tomatlonformation----namenamedd frotromm ththee coarsecoaree,, conglomerateconglomerate

exposureexposuress easteast otof thethe oldold towntown otof AlIIIT,Almy, 1(yoming.Wyoming.

TheThe ~Almy formationformation constconstituteitutodd tht hee basabasall memberr

otof ththee groupgroup..

FoFowkewkess formation-formation ----namednamed fromfrom tthhe lightlight ggrar~y ttoo whitewhite

tuffaceoustuffaceous aniand freshfresh waterwater J..1melimestonstonee depoeitedeposits nearnear

FowkesFowkes ranranchch,, nnortorthh otof EvanetonEvanston. Th1aThis unitunit rapre-repre­

sentasents a reworkedreworked ddeposiepositt otf volcanicvolcanic asashh ..

KniKnighghtt tormation----namedformation named fromm. e~ureexposures otof red,red, pink,pink, w o

FigurFiguree 3. VieVieww eastwareastwardd frofromm AlmyAl.n\.Y, showinshowingg WasatcWasatchh formatiof'ornationn (Veatch'(Veatch 'ss "AlmIIAlmyy fonnationformation"n ) overlyinoverlyinbg EvanstoEvanstonn formationformation.. 3131

yellowyellow,, andand graygray sandstones,sandstones, conglomerates,conglomerates, silt-silt-

stones;stones, andand lID.ldstones,mudstones, inin ththee vicinityvicinity ofof ththee oldold

KnightKnight Station,Station, onon ththee UnioUnionn PacificPacific ShortShort LineLine

Railroad,Railroad, southeutsoutheast ofof Evanston.Evanston.

TracyTracy anandd OrielOriel (1959),(1959), andand GazinGazin (1959),(1959), havehave notenotedd thatthat fresh-waterfresh-water gastropodsgastropods fromfrom ththee FowkeFowkess formationformation areare ofof middlemiddle toto latelate EocenEocenee age.age. TheyThey furtherfurther pointedpointed outout thatthat ththee FowkesFowkes formationformation isis thereforetherefore youngeyoungerr than,than, andand stratigraphicallystratigraphically higherhigher than,than, ththee KnightKnight formation.formation.

InIn viewview ofof ththee aboveabove information,information, EardleyEardley (1959)(1959) pointpointss out:outs

ltV-lith"With thethe recognitiorecognitionn thatthat thethe FowkesFowkes doesdoes notnot occupyoccupy a layerelayel~dd positiopositionn betweebetweenn ththee KnightKnight ar!dand AliiiA.l.lnyy ththee relationrelation ofof thethe KnighKnightt andand AlmAlngy becomesbecomes a problem.problem. InIn thosethose localitieslocalities Wherewhere VeatchVeatch showsshows KnightKnight restingresting directldirectlyy onon ththee AlmyAlnJ;l,, ththee writerwriter (Eardley)(Eardley) hashas foundfound itit impossibleimpossible ttoo deteotdetect anyany realreal break.break. NotNot beinbeingg impelledimpelled ttoo findfind a breabreakk nonoww tha.tthat nono separatingseparating FowkesFowkes isis believedbelieved toto exist,exist, itit appearsappears thathatt ththee AlmyAlmy isis simplsimplyy a basabasall ur..itunit ooff thethe KnightKnight andand ooff nnoo reareall stratigraphistratigraphicc significance.significance. NNoo meansmeans hashas beenbeen foundfound bbyy ththee writewriterr (Eardley)(Eardley) ofof recognjrecognizin.. zingg ththee AlmA.1myy outsideoutside ofof itsits typetype localitylocality jusjustt northnorth ofof Evanston•Evanston.""

VeatehVeatch (1907)(1907) describeddescribed ththee AlmAlmyy formationformation asas thickthick., cliff-cliff- formingforming bedbedss ofof coarsecoarse conglomerateconglomerate (boulde!'8(boulders upup toto oneone footfoot inin diameterdiameter)) andand interbeddeldinterbedded siltstonesiltstone andand claystone.claystone. TheThe coarse-coarse­ nessness anandd brownbrown colorcolor ofof ththee A.lroyAlmy distinguisheddistinguished itit fromfrom ththee WasatchWasatch formation.formation.

TheThe coarsecoarse conglomeratconglomeratee beds,beds, calledcalled !lmyAlmy bbyy Veatch,Veatch, werewere 3322 tracetracedd northwarnorthwardd frofromm Ivan.ivanatons ton 2 ttoo 3 milemileas bb;yy ththoe writerwriter.. TheThe conglomerateconglomerates. thithinn northwarnorthwardd ttoo •a "knif"knit.e edgeedge"" thicknessthiekn •••, , aapproxipp roxi­­ matelmatelyy 1 milmilee soutaouthh ooff ShellShell HolloRolJ.o"w (se(aaee figurfiguree !+)•4). ThThee coconglomernglo"",...­ ateat.. s werweree absenabaentt nortnorthh ofof thithiss vicinityvi.c1nity.. WasatcWUatchh bedbedas ininterfingeterfingerr ldthwith ththoe conglomeratesconglomorat.... AbouAboutt *\ milmile e nortnorthh ooff AlmI.lm;yy StationStation,, redred mudstoneIIlU.daton ••s ofof ththee WasatcWUat chh resreatt directldirectlyy oonn ththee EvanstonEvaneton,, anandd thethe conglomerateoonglomerate.s overlioverliee thethe redred mudllltonmudstones •••.

ThThee writewriterr believebelleve.s that hatt the.. stratat rataa define definedd aass "Almy"Alm1"* (Veatch)(Veatch) nortnorthh ooff EvanstoEvanstonn areare merelymerely a local1('0&1.,, coarscoaraee faeiefaci ••s oatf ththee KnightKnight formationtormation.. TherefThereforeore,, tthhe AlmAlmyy woulllOUldd nonott bbee consideredd a.. vvalialidd formationn n&me.name. TheThe writewriterr agagreereE!s1I witwithh ththee suggestionauggeationas ooff EardleyEardley andand Trac;yy andand Ori.lOriel ththaat tthhee uus.. e ooff ththee n&san..",.e AlmI.lm;yy bbee cIiJIcontinuec1.discontinued.

TheThe writer furtfurtheherr lsuggestuggesus thathatt tht hee orogenicerogenic depositsdeposits pprere­­ viouslrtoualyy rereferreferredd toto asas I.lm;yAlmy andand !:nightKnight formationfOnI!&t iolllls (above)(abov.),, bebe couldered.considered collect1collectivelv elyy andand tenrtl!,dtermed thethe Wasatcwas atchh formationlormation.. TheThe namename nw&eatch"Wasatch" hashas pprioritriority ooveverr "Knight"."Knight".

TheThe wasatchWasatch [annationformation conallconsistl'tas oatf ggrayray,, redred,, anandd yyellowellow,,

COaralcoarse aandatosandstoneneas andand coconglomeratesnglomerat.e.,, witwithh interbeddedinterbedded,, vari-coloredvari-colored

111tatosiltstonen•• s andand mudatonemudstonesa.. SeSeveravenu.l thint hin,, lighlight coloredcolored,, treafreshh­­

_terwater .limeatonealimestones occoccuurr nearnear thethe top ootf ththee sequence.sequence• TheThe eand­sand­ atonstone.. s andand coconglomeratenglomeratHs toforrmm pprominenrominentt leledgesdge8.. WeathereWeatheredd IIUr­sur­ tacufaces areare ottenoften coveredcovered withwith twistedtwisted andand odd-shapedodd-shaped holes,holes, otof allall alsizes.. , givinggiving thethe rockarocks thethe ILappearancppearancee otof &a volcanivolCanicc acoria.scoria. N s ...

. ..:...~ :... ,---'--' - - . :--. - ...... ~ .....:.- --:-. - .

FigurFiguree 4.. DiagrammatiDiagrarranaticc cross-sectioncross- section, , easeastt ooff AlmyAlmy,, showinshowingg interpreteinterpretedd relationsrelations ooff VeatchVeatchT'ss f'AlmIIAlmyy formationformation"" anandd ththee WasatcW3.satchh anandd EvanstoEvanstonn formationsf ormations.. 3344

ThThee writewriterr collectecoUectedd twtwoo specimenspecimenas ooff fisfiahb scaleIcall.s aapproxipproxi­­ matelmatelyy 50 feeteett belobeloww ththoe totopp of ththee Wasatch_atch,, abouabou.tt 1 milmiloe euteast ooff ShelSholll HollowHollow.. FossilizeFooo1li.edd wood wa.....s founf oundd iinn Wasatchh floatfloat

throthroughouughout th t hee areaarea.. ThThe writewriterr founf oundd noo otheotherr fossitoeeill mat.rial.amaterials

iinn ththee WasatcWasatchh tormation.formation.

ThThee Wasatcwae.tchh formationformation 18is ooff earlearlYy EocenEocene ageage.. VertebrateVertebrate

loaillafossils fromm VVeatch«•• tch'. s "Knight"Knight formationformation"" havhavee beebeenn assigneassignedd toto

ththee IysitlV'a1tee zon.one ofof ththee W&satc_atchh stagotagee (lowe(lowerr EoceneEocene)) by GGrangerangerr

(1914(1914)) anandd GGaziaz1.nn (1(1952)952)..

VVeatch'•• tch'. s "A"Alm~y formationformation"" wawass assigne... i gnedd a latlatae PaleocenPaleocenee ageage

b7by Gaz1.nGazin (1942,(1942, 11959)959),, frofromm vertebratverteb ratee remainrama1nos collectecollectedd nearnear

LaLa Barge,Barge, Wyoming.. TTracracy anandd OOrier101l (1959(1959)) believbelievee that hatt ththee bodebeds

referred.referred to asas ttA.l.m;y't"Almy" inin thethe KKemmereremmerer., WyomingWyoming., vicinityy areare

moremore approappropriatelpriatelyy includedincluded inin thethe Evanston formationtonnation.. ThThee writerwriter

beliovoobelieves thatthat ooutcroputcropos fonnerlyformerly mappemappedd aus "AlmyftAlm;y"" iinn ththee EvanstonEvanston

&rM.area areare momorree properlyproperly usiassignegnedd ttoo ththee WasatcW... tch h formationformation (e(se ••e

pagoPage 32).32). Noo fooo11ofossils havehave beenbeen founfoundd iinn ththee typtypoe oect1onsection ooff thethe

"Alm;y"Almy formation"formation" toto claritclarifyy relationerelations iinn thatthat area.area.

BuBurgergerr (19(195555 ) dOlcridescribebedd thethe _atcWasatch stratotrotaa aus havinhavingg beonbeen

clepo.lteddeposited onon a maturemature erosionalerosions! surfacelurtece,, witv1th reliereUetf upup toto 500500

feet.feet. ThUThis featurefeature 18is notnot wellwell expresseexpressed.d inin thethe ETanatonEvanston vicinitvicinityy ..

TheThe WUatchWasatch bualbasal uncontonnitunconformityy repree.representntes &a majormajor hiatus.hiatus•

VuatchWasatch bbededas rutrest unconformablyunconformably 'upouponn roCDrocks fromfrom .arlyearly CretaceousCretaceous l'35 throughthrough PaleocenePaleocene &ge,age, iinn ththee areaarea nortnorthh ofof Evanston.Evanston.

Thick,Thick, coarscoarsee clasticselastics iinn ththee WasatchWasatch formationformation representrepresent anan orogenicorogenic deposit.deposit. SourceSource areasareas areare consideredconsidered ttoo havhavee beenbeen toto thethe 'West,west, inin thethe vicinitvicinityy ofof thethe Wasatc\$satchh MountainsMountains ooff utahUtah

(Burger,(Burger, 1955;1955? Eardley,Eardley, 1959).1959). TheseThese thicthickk clasticselastics blankeblankett largelarge areasareas ofof southwestsouthwest WyomingWyoming andand Utah,Utah, concealingconcealing underlyinunderlyingg struc­struc­ turestures andand lithologies.lithologies. MaximumMaximum reportedreported thicknesthiclmesss ooff WasatchWasatch stratastrata isis aboutabout 3,5003,500 feetfeet.. WasatcWasatchh thicknessthickness nortnorthh ofof EvanstonEvanston rangerangess fromfrom 250250 feetfeet ttoo approximatelyapproximately 600600 feet.feet.

ThThee WasatchWasatch formationformation consistsconsists ofof redred,, brownbrown,, yellowyellow,, andand gragr~y claystoneclaystone,, siltstone,siltstone, sandstone,sandstone, anandd conglomerateconglomerate,, witwithh aa fewfew thinthin,, fresh-watefresh-waterr limestonelimestone bedbedss neanearr ththee totopp ofof thethe sequence.sequence.

wasatchWasatch bedbedss interfingerinterfinger witwithh thethe GreeGreenn RiverRiver andand BridgerBridger formationsformations toto thethe east.east.

UsUsee ofof ththee termtemss "wasatch"Wasatch groupttgroup" and,and, iinn particularparticular,, "Knight"Knight fo:nnation",formation", hashas spreadspread throughouthroughoutt southwestersouthwesternn WyominWyomingg andand Utah.Utah.

TracyTracy andand OrielOriel (1959)(1959) feelfeel thatthat ththee widespreawidespreadd usagusagee ofof thesethese namesnames isis basebuedd onon somewhatsomewhat doubtfudoubtfull correlationscorrelations inin manmanyy instances.instances.

BriggerBridger ill(?) formation.formation. ExposuresExposures ofof green-graygreen-gray ttoo gray,gray, highlyhighly altered,altered, volcanicvolcanic asashh werweree foundfound overlyingoverlying ththee WasatchWasatch formationformation inin twtwoo looalitieslocalities nortnorthh ooff Evanston.Evanston. ThiThiss sequencesequence isis herheree tentativeltentativelyy referredreferred ttoo ththee BridgeBridgerr formationformation onon thethe basibasiss ofof lithologlithologyy andand stratigraphiestratigraphic positionposition.. NNoo fossilfossilss wrewere 3366 founfoundd nthwith whicvbichh ttoo makmakee a• definitdefinitee correlationcorrelation.. OnOnee exposurexpoeuree ofof

BridgeBridgorr (?(?)) wa_ s mappemappedd approximatelapproxl.m&tolyy 2 milemil.. s soutaouthh ootf ththee U_rUpper

NarrowsNarrow, on ththee easeutt bencbench ooff ththee BeaBearr RiveRiverr valleyvalley_. Th•• e seconecond d exposurexposuree waw.as mappemappedd inin ththee southwester80uthweatemn comecon18rr ooff ththee reporreportt areaarea,, wesvaett ooff Alm~y StatStationi on..

ThTh.e BridgeBridgerr (?(?)) formationformation,, nortnorthh ooff EvanstonEvanoton,, 1.is a& hihigtilghlyy decomposedecomposedd claystonclaywtonee slope-slope-formertormer.. Th The claystonclayat onee iais nnoticeabloticeAblyy bentonitibentoniticc.• AbundanAbundantt hornblendehornblende,, biotitebiotit e,, andand basibaa1cc foldaparfeldspar graingrainas iinn ththee claystonc~tonee atstronglronglyy asuggesuueatt a volcanicvolcanic oriorigingin..

BridgBridgee r (?(?)) bodebeds resrutt iinn faultaultt contaccontactt witKlthh thee GanneGannetttt formatiotormationn soutaouthh ooff thethe UUppe_rr NarrowNarro.. s (a(se ..e figurefigure 5) . The coconn-­ tact,, or faul f aultt tracetrace,, i18s expreexpresse•• edd inin thethe topotopographgraphyy byby a narrow,narrow, ahallowshallow troughtrough..

VeatcVeatchh (1907)(1907) detineddefined thothe BBridgeridgerr formationformation u:as:

It ••••.compose comJX) ••d lalargelrgelyy otof volcanicvolcanic uh,ash, inin placplace ..s havinhaTingg a markemarkedd ggreenisrooniahh cut,cast, andand containingg per­per­ ai.tentsistent lIh1towhite calcaroouecalcareous banda,bands, filledfilled Klthwith treah­fresh­ waterwater shellashells thatthat areare identicalidentical inin appearanceappearance withwith thosethose foundfound inin thethe GreenGreen RiverRiver andand upperupper ~atchWasatch beda."beds.*1

TheThe VTitwriteerr v1altedvisited thethe typetype .ectionsection ofof thethe BBridgeridgerr formationformation,, aouthoutsoutheast otf FortFort BridgBridgerer,, Wyoloomingming,, torfor tthhe JlUpurposrPOOee otof atstudyinudyingg thothe litlithologholoUy andand collectingcollecting petropetrographigraphicc aamsamplesplea.. Hee toundfound thethe loworlower te.few hundredhundred t.etfeet ofof thethe typetype BridgerBridger lithololithologicallgicallyy 1dent1-identi­

O&l.cal Klthwith thethe BridgBridgee r (?)(?) atrotastrata northnorth otof Evanaton.Evanston.

Sample.Samples collcollecteectedd tromfrom thethe BridgerBridger typetype asectioectionn andand fromm thethe Figure 5. ViewView northeastwardnortheastward fromfrom justjust southsouth ofof thethe UpperUpper NarrowsNarrows,, sho·showin... ~ gg BridgerBridger (?)(?) fonnationformation inin faultfault contactcontact withwith thethe GannettGannett groupgroup.. NoteNote tOFOgraJ:ilictopographic troughtrough whichwhich marksmarks thethe faultfault tracetrace.. 38

BridgerBridger (1)(?) exposuresexposures nortnorthh ofof EvanatonEvanston werweree comparedcompared microscopi­microscopi­ cally.cally. SamplesSamples werweree tootoo unconsolidateunconsolidatedd toto prepareprepare thinthin sections,sections, andand werewere studiedstudied inin thethe crushedcrushed state.state. SpecimensSpecimens fromfrom botbothh 10-lo­ ealitiescalities containedcontained abundanabundantt quartz,quartz, calcite,calcite, andand biotite.biotite. Plagio­Plagio- clue,clase, hornblendehornblende,, andand magnetitemagnetite werewere presentpresent inin lesserlesser quantityquantity inin samplessamples fromfrom bothboth areas.areas. TheThe mostmost abundantabundant,, andand distinguishing,distinguishing, constituentconstituent ofof allall samplessamples studiedstudied waswas anan oliveolive greengreen clayclay mineral,mineral, whichwhich ththee writewriterr waswas unableunable toto identify.identify. ThisThis ola,yclay mineralmineral isis presenpresentt inin ta.bulartabular andand platplatyy crystalscrystals andand structureles8structureless masses.masses.

TheThe mineraminerall isis slightlyslightly pleochroic,pleochroic, hashas highhigh birefringence,birefringence, andand inin a fewfew crystalscrystals displaysdisplays welwelll developeddeveloped cleavagecleavage inin oneone direction.direction.

PetrographicPetrographic evidence,evidence, combinedcombined withwith stratigraphicstratigraphic positionposition andand lithology,lithology, suggestsuggest a veryvery likelylikely correlationcorrelation ofof thethe greengreen volcanicvolcanic ashash depositsdeposits nortnorthh ofof EvanstonEvanston withwith thethe typtypee BridgerBridger formation.formation.

VeatchVeatch (1907)(1907) assignedassigned thethe BridgerBridger formationformation toto ththee middlemiddle

EoceneEocene (Bridgerian(Bridgerian stage)stage) onon thethe basisbasis ofof fresh-waterfresh-water mollusY.$mollusks collectedcollected fromfrom thethe formation.formation.

VeatchVeatch reportedreported 1,2001,200 toto 1,8001,800 feetfeet ofof BridgerBridger fonnationformation atat ththee typetype 100a11localityty. .

TheThe followingfollowing sectionsection wawass measuredmeasured approximatelyapproximately 2 milesmiles southsouth ofof ththee UpperUpper NarrowsNarrows,, inin sectionsection 9,9, T.T. 1717 N.N.,, R..R. 120120 w.:W.: "39 Fowk,§Fowkes fOrmltionformation BrldgerBridger (1)(?) formationformation FeetFeet

Claystone;Claystone; bentonitic;bentonitic; turquoisturquoisee toto oliveolive greengreen,, pinkpink,, anandd gray;gray; floatfloat covereooveredd withwith small,small, blacblackk siliceoussiliceous grainsgrainl,, 1 ttoo 2 mmnun.. inin diameter;diameter; slope—former«.•*«..•..*...•«•••.••••••••••••«•••81ope-ro~er...... • 206206 CoveredCovered slope;slope; lightlight graygray claystoneclaystone float...... float...... 6,65 ClaystoneClaystone;; bentoniticbentonitio;; pink,pink, maroon,maroon, andand lightlight gragrayy toto gray-green;gray-green; slope-slope- fro~er...... o rmer*••••••••«••••••••••••*•••••«••••••*••••••• 2020 CovereCoveredd slope...... slope5 511 Claystone;Claystone; bentoniticbentonitic;; lightlight brown,brown, gray,gray, greengreen,, andand redred;; slope-former...... slope-former....• ••• 1212

TotalTotal BridgerBridger (?(1)) formatioformation...... n 354354 FOWKEFOWKESS FORMATIONFORMATION

TypeType localitylocality

TheThe FowkeFowkess formationformation waswas namednamed byby VeatchVeatch (1907)(190?) fromfrom exposuresexposures nearnear

FowkesFowkes RanchRanch inin thethe SESE~£ ooff sectionsection 32,32, T.T. 1717 N.,N«, R.R. 120120 W.W. (approximately(approximately

9 milesmiles northnorth ofof Evanston,Evanston, WYoming).Wyoming). VeatchVeatch interpretedinterpreted thethe FowkesFowkes for-for­ mat10nmation asas overlyingoverlying thethe thickthick conglomerateconglomerate sequence,sequence, whichwhich hehe ll&<"D.ednamed "Al.my"Almy formation",formation", anandd underlyinunderlyingg thethe wasatchWasatch formation.formation. ThisThis interpretationinterpretation bashas sincesince beenbeen provenproven erroneouserroneous (Tracy(Tracy & Oriel,Oriel, 1959).1959). TheThe FowkesFowkes isis nownow knownknown toto bbee stratigraphicallystratigraphically higherhigher thanthan thethe wasatchWasatch formation.formation.

AgAgee

TheThe FowkeFowkess formationformation isis ofof latelate EoceneEocene age.age. DwightDwight TaylorTaylor identifiedidentified fresh-waterfresh-water gastropodgastropodss fromfrom thethe typtypee localitylocality ofof thethe FowkesFowkes andand fromfrom ex-ex­ posurePOSUr8Ss nearnear Sage,Sage, WyomingWyoming,, asas latelate EoceneEocene oror possiblypossibly earliestearliest OligoceneOligocene

(Tracy(Tracy & Oriel,Oriel, 1959).1959). AccordinAccordingg ttoo Casin„azin (1959):(1959):

ttFresh-water"Fresh-water snailssnails collectedcollected bbyy thethe writerwriter (Gazin)(Gazin) inin 19531953 fromfrom ththee typetype localitylocality ofof thethe FowkeFo~ess werewere determineddetermined bbyy ReesideReeside asas EoceneEocene inin age.age. TheseThese togethetogetherr witwithh samplessamples .fromfrom otherother local­local­ itiesities mappeinappedd byby VeatcVeatchh asas Fowkes,Fowkes, werweree deten~eddetermined byby DwightDwight TaylorTaylor aass BiomphalariBiomr:.ha.lari!a F!eudo/llTI.lwnia,pseudoammonia, aa formform reportereportedd ttoo bbee abundantabundant inin BridgerianBridgerian middlemiddle EoceneEocene a."1dand knownknown fro!!J.from severalseveral UintanUintan occurrancesoccurranees asas establisheestablishedd bbyy fossilfossil mammaliam.ammalia.. AnAn earlyearly

40 41

OligoceneOligocene ageage possibilitypossibility isis alsoalso suggestedsuggested byby him.him fromfrom a BeaverBeaver DivideDivide occurrance;occurrence; however,however, thethe ageage relationshipsrelationships therethere areare notnot entirelyentirely clearclear (Gazin),(Gazin), soso thatthat fromfrom thethe evidenceevidence ofof thisthis localitylocality alonalonee thethe OligoceneOligocene possibilitpossibilityy maymay bebe uncertain."uncertain ."

FowkesFowkes exposuresexposures havehave beenbeen reportedreported fromfrom thethe EvanstonEvanston vicinityvicinity nort.h-north­ wardward ttoo thethe centralcentral portionportion ofof FossilFossil BasinBasin inin a beltbelt approximatelyapproximately 4040 milesmiles vide.wide.

TheThe FowkesFowkes formationformation restrestss conformablyconformably uponupon thethe BridgerBridger (1)(?) fonnation.formation.

TheThe contaccontactt betweenbetween thethe BridgeBridgerr (?)(?) andand FowkesFowkes formationsformations isis notnot sharp.sharp.

DepositionDeposition appearsappears ttoo havehave beenbeen continuouscontinuous fromfrom thethe BridgeBridgerr (?)(?) fonnationformation througthroughh ththee FowkeFowkess fonnation.formation. TheThe contact,contact, therefore,therefore, isis arbitrarilyarbitrarily drawndrawn.. TheThe BridgerBridger (1)(?) isis characteristicallycharacteristically anan oliveolive greengreen color,color, whereaswhereas ththee FowkeFowkess isis typicallytypically lightlight graygray toto whitewhite.. ColorColor differencedifference isis ththee onlyonly

Criterioncriterion availableavailable forfor establishingestablishing thethe arbitraryarbitrary contact.contact. WherWheree BridgerBridger

(1)(?) isis absent,absent, thethe FowkesFowkes restsrests unconf01"'".ui8.olyunconformably uponupon thethe WaDatchWasatch formation.formation.

TheThe FowkeFowkess formationformation occupiesoccupies thethe higheshighestt stratigraphicstratigraphic positionposition inin thethe areaarea ofof thithiss report.report.

EardleyEardley (1959)(1959) pointspoints outout thethe factfact thatthat FowkesFowkes exposuresexposures areare closelyclosely associatedassociated withwith a majormajor zonezone ofof normalnormal faultingfaulting inin southwesternsouthwestern WyomingWyoming andand adjacentadjacent partsparts ofof Utah:Utah;

"Most"Most ofof thethe faultsfaults cutcut ththee Fowkes,Fowkes, butbut thethe confinementconfinement ofof ththee FowkeFowkess volcanicvolcanic outwashout wash toto thethe belbeltt ofof faultingfaulting indicatesindicates thatthat a mainmain drainagedrainage wayway hahadd beenbeen establishedestablished beforbeforee FowkesFowkes deposition,deposition, andand therefore,therefore, thatthat deformationdeformation alongalong thethe zonezone hadhad occurredoccurred beforbeforee FowkesFowkes time.time. TheThe deformationdeformation mightmight wellwell havehave beebeenn associatedassociated withwith saltsalt intrusion,intrusion, solution,solution, andand collapse,collapse, alongalong withwith faulting.faulting. ItIt 42

seem....s possiblepossible,, thereforetheretore,, thathatt tht hee major tafaultult8s ha!wid bbeeoen ..establishetabU.hod d beforbeforee FowkeFowk.. s timet 1mo,, anandd thathatt movemenmov.mentt continuecontinuedd on thet hemm attezw.rd."afterward."

ThTheo FowkeFowke.s formatiofonnatienn consistconsistss ofof lighU ght gragrOTy ttoo "whithitee ttuffaceouuffaceouss matematerialrial,, with interbeddeinterbeddedd thithinn layerLlyerss ooff fresfre.hh water limestonelimestone,, anandd locallocal,, thithinn lenae.lenses ooff conglomerate.conglomerate.

FreshFresh watewaterr gastropodgutropod.s werWIree collectedcollected by ththee writewr11~err frof romm seveleven 10cal-local­ itieitle.s inin ththee areareaa northnorth ootf EvanstonEvanaton.. IdentificationIdentif'icatlolllls werWIree madmadee bbyy thethe writerwriter..

ColloctCollectioi onn takotaken fromm ththoe SESE t£ ooff ...sectiotion n 28,, TT.. 18 I. N.,, R. 12UO0 WW..Is

PhysPlu>J,a cf.cf • f.P. longiWlculalongiuscula !leMeeekk &8< HaydeHaydenn

Plm'Physa pleromatiplo!'Cll!ftiss WhiteWhite

~.p.Physa sp.

CollectioCollectionn takantaken fromm thethe NNEE ~£ ofof .ectionsection 1,1, T.T. 1616 N«N. , RR.. 121121 W.I:

~ ct. f. 10ngiuacuJ.a !leek 8< Haydon

viviaNOViviparus trochitol'1ld!!trochiforalis , (!leek(Meek 8<& Haydon)Hayden)

GU'uJ.utGyraulus oogualiaaequalis WhitoWhite

Collectionn takentaken fromm thothe SESE t£ ofof ••sectioctio n 33,, T.T. 1717 N.N.,, R. 120120 W.IW.:

GGyraulusuaullll, HautH,a.equa^.ie (White)(White)

C,rinulorb1tCarinulorbia utahenoi,utahensis LaLa RocqueRocque

Pltnori>itPlanorbis 'I!!ctr.!>iliaspectabilis WhiteWhite

CollCollectiooctionn fromfrom thathe NWHW t£ NEMB ~£ ofof ••sectioctio n 21,21, T.T. 1818 N. , R.. 121200 W.sI

PhYp,Phys& cf.cf. f.P. longiuocul&lon^iuscula !leMeeokk 8<& HaydeHaydenn

~Physa cf.cf. f.P. rlJomhoide,rhomboidea IIeokMeek 8

PhYuPhysa p1ero!!ftispleromatis, WhiteWhite 4343

f!l1UJ3SM bridae!'!l1fiobridgerensis MooMeekk

CollectionCollection frofromm thethe SVSW 1;£ BESE l£~ ofof .ectionsection 3333,, T.T. 1717 NN..,, R.R. 120120 V.IW.J

GGyrauluITIul"!ls &!

GnauluoGyraulus mimilitarislitarl.o, (Whit.)(White)

Vivip&"'"Viviparus trnchifotrochiformi,,,l.s ((MeeMeek & ~eHaydenn ))

Vivipan!!!Viviparus palud1n",toI'lliopaludinaeformis (Hall)(Hall) V1vip&!llIViviparus .p.sp.

C'rinul0rb1eCarinulorbis utahautahensinails LaLa RocqueRocque

HoloopiraHojospira cf.cf. !!.H. l!o~leidyi ((Meek!Ioek))

DitCUIDiscus cf.cf. 1<.1. ~",nonaralstonensiis. (Coc(Cockerellke roll))

CollectionCollection trofromm thothe NWNW 1;£ SWSW I£. ofof sectio.ectionn 3030,, T.T. 1818 NN..,, R.R. 120120 V.W.sI

Vivip&n!!!Viviparus trochifo,1Diotrochiformis ((MeeMeek & ~on)Hayden)

ViviPln!!!Viviparus !?Iludin",fo'!'itpaludinaeformis (Hall)(Hall)

CollectionCollection fromfrom tthhe SSVW 1;£ ootf sectionn 3636, TT.. 16 N. N.,, RR.. 121121 V.IW.s

GGyrauluyr&ul"!ls fetaliuguallJs ((White Whit.))

• Pll[lorbi,FXanorbis 'p!ctabi).iospectabi^ls (White)(White)

CarinulorbioCarinulorbis utahensiutah,m.ios LLaa RocqueRocque

ViviparuVivip&r1!!s troehifoimitrnchifo.1Dios (Mee(!leek k& ~on)Hayden)

HolospiraHo10.pira, cfcf.. !!H. l!o~leidyi ((MeekMeek)

ThThee abovabove fossi1'oe.11l assemblageueemblagees havhavee beenn reportereportedd frofromm tht hee latlatee EoceneEocene strat.trataa ooff centracentrall Utautahh (X(Laa RocqueRocque,, 1I960)960)..

PetrographPetrographyy

ThThee writewriterr madmadee petrographipetrographicc comparisoncomparieoIl8s ooff sampleeampl_s ootf FowkeFowkess formatioformation 4444 fromfrom thethe EvanltonEvanston vicinitvicinityy, andand NorwoodNorwood formation troru.from north.northeasterutemn utah,Utah, inin anan efforteffort toto o~clarify relationsrelations bet""onbetween thethes.. e t,.,two .lsimila.m1lar dopooitdeposits ••.

SuggSuggeste.. ted d correlationcorrelation ofof thethe FonFowke.. s andand NonooodNorwood byby Eal~leEardley;r (1(1959959)) ledled tot© thothe petropetrographigraphicc study.study.

ElevenEleven thinthin sectionssections V8rewere preparedprepared fromm specspecimenimeNIs collectecollectedd fromm bothboth

FowkesFowkes andand NNorwoool"1lOodd upoIIuree.exposures. ThinThin .ect1ol'lllsections cocoululdd not.not bebe preprepareparedd frofrom

••severaveral l samsamplepleas oollected,collected, duedue toto lacklack ofof cotlloUdat1cm.consolidation. ThesThetlee lmunconcon­­

Bsolidateolid.tedd asampleampl ••s wrewere studied.studied inin a cruscrushehedd at.tstate•• .

TabulatedTabulated ob,oNationaobservations fromfrom thothe petrographicpetrographic analyoiaanalysis followstollow.. 1IinMin­­ eraerall percentageapercentages areare ••estimatetimat ..s atof thethe writer.writer.

sampleSample colloctedcollected frofromm tbothe FonFowke.. s fonnationformation l.nin ththoe moutmouthh ooff SpringeSprings

C&I\1On:Canyons NWNW I;£ swSW 1;,£, .ectionsection 3333,, T*. 1717 N.N.,, R.R. 1.20120 W.II.,, approximatelapproxLmatelyy 6060

feet.ett abovabovee thethe bu.base ofof thethe formationformation.. HandHand speespecimelmenn lighlightt gragrayy toto

voverrry lightlight graygra;r,, finfinee ggrainedrained,, granulagranularr texture.texture. DarDarkk mineralmineralas areare

abundant,abundant, ggivinivingg a oalt-and-peppesalt-and-pepper aappearanceppearanoe..

MineralsMin.raD::

PrimarPrimarry Es.entialEssential

volcanivolcanioc glasgl&aas 20%20$

quartquartsz 20%

plagioclasplagioclaoee 13%

AccessorAcceaBo r:ry

hornblendhornblendee 3%

biotitbiotitee 1%

magnetitMagnetitee 1% 45

Seeonda~JSecondary AlterationAlteration

ser5.citesericite U1$

hematithsmatitee 0.5%0,5$

liaonitlimonitee O.s%0,5$

IntroduceL'1t roduced.d

calciteealeite 40$

TexturesTexture I

Pyroclastic;Pyroclastic; aphaniticaphanitic;; grain.agrains eq,uidimensional.equidimensional, lessless thathann 11

mmmm.* iL.,n diameter;diameter; graingrainss euhedraeu.~ed.!'all ttoo subhedl'al;subhedral; nnoo orientation.orientation

SpecialSpecial feature$:featuresi

GlassGlass isis chieflychiefly iinn thethe formform ooff shards.shards. FeldsparFeldspar andand 8lilphi­aaphi-

bolbolee ccrystal ryatalss areare predominantlypredominantly euhedrAl.euhedral* QuartsQuarts gr&inagrains areare

subsubrounde rounded.d toto rounded.rounded.

Qbsel"'V'ationsObservations ;,

ThisThis .6I'nplesample isis c:lauii'iedclassified asas a crystacrystall tuff,tuff, havinhavingg a rhyo­rhyo-

dAcitedacite compositioncompositien.* MixturMixturee ofof glassglass shardsshards,, euhedraeuhedrall crys­crys­

tals,tals, and.and rounderoundedd quartquartzs grainsgrains indicateindicatess thatthat thisthis aedimentsediment-

originatedoriginated asas aann aehf'allashfall inin ..a regionregion undergoinundergoingg fluvialfluvial andand

lacust.rinelaeustri.:-: sedimentation..imentation* CalciteOaioite cement,cement, lenticularlenticular eros8-cress-

lamination,lamination, andand freshfresh watewaterr gastropodsgastropods inin ththee bebedd supportsupport

ththee concept.concept •

Samplsamplee collectecollectedd fromfrom ththee FowkesFowkes formationformation inin thethe moutmouthh ofof

SpringsSprings CanyonCanyon:s MNWW £~ swSW i,£, sectionsection 33,33, '1'.T* 1717 N.,N*, R.R. 120120 \i.,W., ap­ap­ pl"oxirnatelyproximately 9090 feetfeet &hoveabove thethe basbasee ofof thethe !onnation.formation. HandHand 46

specimenn gragrqy ttoo lighlightt blue-grayblue- g ~,, ththee blubluee tintintt beinbeingg verTer:ry pronpronounceounced.d GranulaGronul&rr texturetexture,, withh graingrain.s £* tto o |, mm...., iinn diameter.. AbundanAbundantt derkdark mineralminoralas anandd scatterodscattered dardarkk gragra;yy ttoo purplplrplee quartzitquarta1toe pebblepebbl.. s givgiToe a salt-and-peppsalt-end-peppere r aappearanceppearance.•

SamplSamplee studieetudiedd iinn ththee crushecruahedd sstatet ate..

MinMineralserilla,.

volcanicvolcanic glasgluls (.hardo)(shards)

quartquartsz

plagioclaspl&g1oclosee

hornblendehornblende

biotitbiotitee

magnetitmagnetitee

homat1tehematite

limonitelimonite

calcitecalcite

s.ricitesericite

IndeIndexx otof retractionrefraction otof ththee gglasslue ::

bbetweeotweenn 1.1.5511 anandd 1.1.5522

SamSamplplee collectedcollected fromfrom thethe FowkeFow.. s formationformation approximatelapproximatelyy 1I milemile northnorth ofof Chrutenll8nChristensen Hollow,Hollow, onon ththee east-facineut- racingg slopelopee ootf WhitneWhitneyy Can,yonsCanyon: HENE *£ HEN E *,£, .ectiosection 29,29, T.T. 1717 NN.. , RR.. 120120 W.W.,, aboutabout 150 feetfeet aboveabove tthhe bbasuee otof tthhee formation.formation. Ve1'7Very fintinee ggrainedrained,, somewhasOmeV1att ggranran­­ ularular tmure.texture. AAbundanbundantt dodarri

toto pupurplrploe quartsitoquartzite give a o&l.salt-and-peppet - and-pepperr appearanceappearlnce.. (Cruohod(Crushed 4477

..sample)mplo). .

MineralM1norwls I

volcanivolcanicc glasgluas (shards)(shards)

quartz a

plagioclasplagj.oclaae •

hhornblendornblendee

magnetitmagnetitee

hematithematitoe

limonitlimonitee

calcitecalcite

cayclay miner&l8minerals

IndexIndex otof refraotionrefraction orof ththee gglasslas.:;

between 1.511.51 "-an~d 1.521.52

SampleSample collectedcollected f'rofrom!fl . thethe .FOldee!Fowkes formationformation approximatelnpprox1m&telyy 1 milemile

northnorth ofof Chri8tenaenChristensen HollowHollow,, onon thethe eut-faoeast-faciningg elilopeslope ooff WhitneWhitneyy Can­Can­

yonsyons NENE ~| NENE ~,|, ..sectioction n 29,29, T.T. 1717 NN..,, R.. 120120 W.,¥., approximatelappl'Ox1m&telyy 2255 teetfeet

aboyeabove thethe buebase ofof thethe formation,.formation. HHanandd sspecimepecimenn veryvery lightlight blubluee toto

lightlight bbluluee gHY'gray.,. VeVerryy finefine grained,, mas.ivemassive text,ure.texture. ScattereScatteredd dark:dark

minerallminerals givegive •a lalt-and,-salt-and-peppepepparr appearance.appearance. Not~Notabl~b l.e iiss a& oone-halne-hal!f

inchinch bandband ofof l'Oundedrounded oloyclay pebblpebbles.. , !| toto 1 lDllram.. inin di_ter.diameter.

HineralasMinerals s

PrimaI7Primary ~sentielEssential

volcanicvolcanic gglaslasss 25%25$

quart.quartz 25%25$ 48

plagioelasplagioel&aee 5%5$

.lCC.IOAccessorryy

homb1ondehornblende 11>1%

bibiotitotitee 11>at

magnetitemagnetite 00.5.5$%

SecondaSecondarr.1y AlteratioAlterationn

sericisericittee 10%$

limonitelimonite 0.5$%

IntroducedIntroduced

calcitecalcite 33%$

Textures:

PyroclasticPyrocl&atic;; aphanitic;; crystalcrywtws anhedraanhedrall ttoo asubhedrslubhedrel;;

ggrainrainas 1les •••s thathann 1 mmm .. iinn diameterdiameter;; nnoo preferrepreferredd orienorien­­

tattationi on..

SpeciaSpeci all toaturea:features:

ThThee glasgl&ass fragmentfragmentes araree inin tht hee forformm ootf shards h&rdes anandd pumipumicece.*

ShardShardas araree delicatdelicatee anandd unbrokenunbroken.. VesicleVNiol•• s iinn ththee pumipumiccee

fragmentfragmentss araree notablnotehlJ'y elongated.elongated.

ObservationsObservational:

This. specimes pecimenn i10s classifiecluaitiedd a..s a crystacrywtall tufftuft,, havinhavingg aa

rhyodacit~.cltee compositioncompositi on.. ThThee primarprimar,yy procesproc •••s o01f dedepositiopoeit1on

representerepre.entedd herheree iiss a volcanivolcanicc ashfalluMall.. Delicate, J Wlbrokanunbroken

shardahardas suggesl uggeatt littllittlee oorr nnoo mechanicame chanicall transportatiotransportationn afterafter

originaorig1nell ddepositionepoeition.. 4949

SampleSample oolleotedcollected frofromm thethe FowkesFowkes formationformation duedue weswestt ooff A~Almy

Station.Station. TakenTaken alongalong roadsideroadside onon thethe westwest sideside ofof BeaBearr RiveRiverr Valley,Valley, approximatelyapproximately t£ milemile southsouth ofof thethe mappedmapped area,area, aboutabout 3535 feefeett aboveabove thethe basbasee ofof thethe formationformation.. HandHand specimenspecimen lightlight blue-gray.blue-gray. VeryVery finefine grained,grained, massivemassive texture.texture. DarkDark mineralmineralss occuroccur inin clusters.clusters.

SampleSample studiedstudied inin thethe crushedcrushed state.state.

Minerals:Minerals?

volcanicvolcanic glaasglass (shards)(shards)

plagioelasplagioclasee

quartzquartz

homblendehornblende

magnetitemagnetite

hematitehematite

limonitelimonite

calcitecalcite

o4;y'mineralsclay minerals

IndexIndex ofof refractionrefraction ofof thethe glaas:glass:

betweenbetween 1.511.51 andand 1.521.52

SampleSample collectedcollected fromfrom thethe FowkesFowkes formationformation duedue weswestt ofof Al.myAlmy

Station.Station. TakenTaken alongalong roadsideroadside onon thethe westwest sideside ofof BeaBearr RiveRiverr Valley,Valley, approJd1ll&telyapproximately i£ milmilee southsouth ofof thethe mappedmapped area,area, aboutabout 5050 feereett aboveabove thethe basebase ofof thethe formation.formation. HandHand specimenspecimen lightlight blue-gray,blue-gray, withwith scatteredscattered grainsgrains ofof biotitebiotite andand hornblendehornblende givinggiving a salt-end-peppersalt-and-pepper appearance.appearance. MediumMedium grained,grained, granulargranular texture.texture. 5050

!lineMinerals raJa,:

PPrimarri.m&r.ry EalentialEssential

plagioelaspastoclasee 30$

volcanivolcanicc glaa.glass 10$

ququartartsz 5%

AccessorAoceaeor:ry

hornblendhomblendee 5%5$ magnetitmagn.titee J%3$ biotitbiotitoe 11%$ claclayy minoraJaminerals 9%9%

SecondarSooondar.ry lit.Alteratio rationn

claclayy minoraJaminerals 6%

hematithematitoe 0.5$

limonitlimonitoe 0.5$

IntroduceIntroducodd

calcitcalcitee JO%30$

TextureTexture.s

PyroelaeticP)-Toclastic;; hypocrystallinehypocryotalllno;; phaneritiphanerl.ticc (grain(grairuos 1 ttoo 5 mm..

iinn diameter)di_tor);; crystalor.rotalJls araree anhedraanhedrall ttoo oeuhedraluhodral..

SpeciaSpeciall ffeatureseatures:s

Glas01... s fragmentfragmentss araree rounderoundedd ttoo subrounded. ubrounded.. MoatMost ootf ththee 01")'11-crys­

talt alJls displadioplayy alteratioaltarotionn bordersbordoro.. Massiv_oivae calcitcalcitee filltillos voinoveins

anandd surroundIUrroundss clustercluatel'8s ootf crystalcryat&las anandd glaae.glass. Sl51

ObservationsObservations s,

ThisThis speoimenspecimen isis classifiedclassified asas a tuffaceoustuffaceous sediment.sediment.

Mechanical.Mechanical transportationtransportation followingfollowing thethe originaoriginall ashfallashfall isis in­in­

dicateddicated bbyy thethe roundnessroundness ofof ththee glassglass fragmentsfragments andand dominantdominant an­an-

hedralhedral andand subhedralsubhedral formform ofof thethe crystals.crystals. WeatherinWeatheringg ooff thethe

samplesample hahass attainedattained a moderatmoderatee degreedegree.. MuchMuch ofof thethe glassglass isis

davitrified,devitzified, andand manymany ofof thethe mineralmineralss displaydisplay alterationalteration borders.borders.

SampleSample collectedcollected fromfrom ththee }i'owkesFowkes ionnationformation duedue weswestt ofof Almy'Almy

Station.Station. TakenTaken alonalongg roadsidroadsidee onon thethe westwest sideside ofof BearBear RiverRiver Valley,Valley, approximatelyapproximately £t milmilee southsouth ofof thethe mappemappedd area,area, aboutabout 7575 feetfeet aboveabove thethe basebase ooff ththee formation.formation. HanHandd specimenspecimen lightlight graygray toto gray.gray. Ex­Ex­ tremelytremely finefine grained,grained, massivemassive texturetexture.. GrainsGrains ofof darkdark graygray toto purplepurple quartzite,quartzite, ~$ ttoo 1 mmmm.. inin diameterdiameter,, areare scatteredscattered throughoutthroughout ththee speci­speci­ men.men. NumerouNUi'1leroUSs shellshell fragmentsfragments a.reare scatteredscattered throughoutthroughout thethe sam.ple.sample •

SmallSmall fractures,fractures, filledfilled withwith chalk-llhitechalk-white clay,clay, cutcut acrossacross graingrainss andand shellshell fragmentfragments ••.

Minerals~.d.ne ra.ls !1

PrimaryPrimary EssentialEssential

volcanicvolcanic glassglass 12%

plagioclaseplagioelase 6%

quartzquartz k%4%

AccessorACCe8sor.vy

cristobalitecristobalite 1%

organiorganicc materialmaterial 1% 5252

magnetitemagnetite 0.5$%

clclaeyy minmineraleralas 25%25$

SecoSecondarndar,yy AlAlteratiot orotionn

cleyclay minmineral.roles 45%$

hematihematittee 0.0.2525%$

limonitelimonite 0.25%$

IntroducedIntroduced

opalopal 55%$

TextureTexture:s

PyroclasticPyroclutic;; aphanitiaphoniticc ((graingroinos eequidimensional)quid1menoional);; glasglues andand

quartquart.z ggrainroinos araree angularangulor;; Cr,ylltalacrystals areare subhedral ubhodrall ttoo oueu­­

hedru;hedral; nono preferrepreferredd orientatioorientationn noted.noted.

SpeciaSpeciall te.tfeaturesurelsl

OrganiOrganicc materiamateriall Ii s. presenpreeentt aass longlong,, curvecurvedd fragmentsfragments.. ThisThis

materiamateriall exhibitOJdlibUIs wavwavyy extinctionextinction,, fibroutibrouos texturetexture,, andand

pleochroismpleoehro1lm.. NearlNearlyy alalll veinveinos anandd ....vesicle1cl .. s araree filletilledd 101wit thh

oopapall and cristobalitec riltobalite.. ManManyy ooff ththee glasglues fragmentfrogmontes exhiexhibibitt

alterationn rimriDs ootf claclayy mineralsminerals.. ThThee centracentrall portionportion.s otof

severaseverall glasgluse fragmentf'ragmentas ar&"e opalizedopalised.. SeveraSevera!l crystalcryat&les havehave

beebunn completelcompletelyy alterealteredd ttoo clacleyy mineralsmine rala,, retainingg ththe

originaoriginall crystac ry. tall outlina.outline.

ObservationOb•• rvatlon.es IJ

ThiThils specimelpoc1menn i11s classifieclMe1t1edd a..s a vitrivitricc tufft uff.. MeMechanicachanicall transportatiotronoportat1onn afterr originaoriginall depositiodepoo1tionn i10s nonott apparentapparent.. TheThe 53

samplesample hashas undergoneundergone extenaiveextensive weathering.weathering. MostMost ofof thethe voloanicvolcanic

gl&l8glass isis devitrifieddevitrifled andand thethe mineraminerall grainsgrains havhavee beenbeen alteredaltered

ttoo clays.clays.

SampleSample collectedcollected fromfrom thethe FowkeFowkess formationformation approximatelyapproximately 2,0002,000 feetfeet nortnorthh ofof thethe mouthmouth ofof ChristensenChristensen Hollow:Hollow: swiSW £ HNEE i,£, sectionsection

2929,, TT.. 1717 N.N.,, R.R. 120120 We#W., aboutabout 4040 feetfeet belowbelow thethe totopp ofof thethe formation.formation.

HandHand specimenspecimen lighlightt gragrqy toto gra;y.gray. FineFine grained,grained, granulargranular texture.texture.

Small,Small, roundedrounded pebblepebbless ofof clayclay disseminateddisseminated throughoutthroughout ththee sample.sample.

ScatteredScattered darkdark mineralmineralss givegive a aa.J.t-and-peppersalt-and-pepper appearance.appearance. WeatheredWeathered surfacesurface isis ververyy rougroughh andand pittedpitted.. SampleSample studiedstudied inin ththee orushedcrushed state.state.

}f1neralsMinerals :

volcanivolcanicc glasglasss (shards)(shards)

quart.quartz

plagioclaseplagioelase

hornblendhornblendee

biotitebiotite

hematitehematite

limonitelimonite

clayclay mineralaminerals

calcitecalcite

IndexIndex ofof refractionrefraction ofof ththee glus:glass:

approximatelyapproximately 1.511.51

SampleSample collectedcollected fromfrom thethe FowkesFowkes formatiofo~tionn approximatelapproxL~telyy 2,0002,000 teetfeet northnorth ofof thethe mouthmouth ooff ChristensenChristensen HollowlHollow: SIVW i£ MENE i,i, sectionsection 29.29, 5544

TT.. 17 I»N.,« RR.. 121200 W.W.,, abouaboutt 60 feefeett belobeloww ththee totopp ooff ththoe formation.formation.

HanHandd specimes pecimann lighllghtt graygrOT.. ExtremelExtremelyy finfinee grainegrainedd ttoo massivmao.1vae texture.texture.

NumerouNUlllIIl'OUSs pebblepecbl.. s ootf claclqy scatterescatteredd throughouthroughoutt ththee sample.sample.

MineralsMl.neralo'i

PrimarPrimar,ry Eo.ent1alEssential

• volcanivolcanicc glglaso..s 40W%%

quartquartss 1%1%

AccessorAccelsoryy

magnetitmagnotitee 1%

SecondarSecondaryy UteAlteratior'at1onn

cla041"y mineralm1n.relos 3%3%

lotroducedIntroduced

calcitcalcitee 55%

TexturesTexture:

Pyreclaotic;Pyroclastic; aphanitic|; holohyalineholoh7al1ne;; anandd vitrophyric.vitrophyric.

SSpeciapeciall featurel'features:

'l'heThe volcanivoloanicc glu.glass consistconeutss primarilyprimarily ofof delidelicatcatee .shardsharoa..

FFe.. w pumicpumicee fragmentsfragments araree prepresentsent.. TheThe volcanivolcanicc glasgluas andand

mineralmineral cryacrystalt &l.as areare cementedcemented togethertogether withwith calcitcalcitee .. TheThe

calcit.calcite oceurlioccurs 58as :mae.lvemassive ageregataggregate•• s ooff minuteminute cl78tala.crystals.

ObaelTationsObservations :

ThisThis opecimaspecimen i.is clclassifie.... ifiedd asas a vitricvitric tuff.. lIochan1cMechanicaall

traneportationtransportation afterafter tthhe orioriginagl nall ddepositioepo.itionn otof thethe phash 18is nnoott

apparent.apparent• Th1aThis osamplamplee ohowshows ver,rvery llttlolittle 0sig1gnn of ""ather1ng.weathering. 5555

Samplsamplee taketakenn fro1'rom.m ththee FowkeFovk88s formatioformationn iinn a• readouroadcutt betweenbetween

SpringSp~s CanyoC~n and ChristenseChriatol'lllonn HollowHollow:s NNEE |l; MNES |l;,, ..sectioction n 3232,, TT.. 1717

N.N.,, RR.. 121200 W.W.,, abouaboutt 5500 feetfeet belobeloww ththee totopp ootf ththee formationformation.. HandHand

specimespecimenn gragrqy ttoo gragn;yy brownbrom.. MediuMediumm grainedgrained,, granulagranularr texture.texture.

ScattereScatt.redd hornblendhomblendoe anandd biotltbiotitee graingrainas givgivee a salt-and-peppe.alt-and-pepperr appear­appear­

anceanett.. SamplSamplee studiestudiedd iinn ththee crusheol'Wlhedd state.state.

Minerals:Minerals s

volcanivolcanioc glasglao.s (angula(angularr))

quart.quartz

plagioelasplagioclasee

hornblendhomblendee

biotitbiotitee

magnetitmagnetitee

hematithematitee

limonitelimonite

clac4)

calcitcalcitee

IndexIndex otof refractionrefraction ofof thethe glglass.... s:

approximatelyapproximately 1.511.51

SampleSample colleotedcollected fromfrom thethe FowkesFowkes tor.matlonformation approximatelapprox1matelYy 1,0001,000

rNtfeet _atwest otof thethe dirtdirt roadroad 1II1erewhere itit erosl.crosses thethe hilltophilltop jWltjust sosoututhh

ofof SSpringp~s ~nlCanyons swl;SW £ SESE l;,£, .ectionsection 32,32, T.T. 1717 N.,N., R.. 120120 w.,W., aboutabout

15 to.tfeet bobeloloww thethe toptop ofof thethe fo_tion.formation. HandHand .pecimespecimen grqgray toto grqgray brownbrown limestone.limestone. VoryVery finofine grained,grained, .,...iYemassive texture.texture. C4)

SampleSample studiedstudied inin thethe c"",hedcrushed .tato.state.

lI1nMineralsor&1e:*

calcitecalcite

quartsquartz

opalopal

magnetitmagnetitee

hematithematitee

limonitlimonitee

No volcanicvolcanic glasglues 1.8is ppresenresent inin thithiss samplesample.. ThisThis represent.represents

&a ffresreshh vatewater time.tonelimestone bedbed withinwithin tthhe FowkFowke ..s tormation.formation.

PetrographPetrograph;ry otof NorwooNono:>edd tutttuff

SempleSample collecteoollectedd fromm ththoe NorwooNono:>edd tuftuftf approximatelapproJdmatolyy £~ milmilee euteast ooff UtaUtahh HighwaHighwayy 66, alonalongg ththoe roaroodd 1Ih1whicch leadl eodss uupp NorwooNono:>edd Canyon,Canyon, neanearr PortervillePorterville,, UtahUtah.. SamplSamplee wa.....s taketakenn frofromm ththee totopp ootf ththee formation.formation.

HanHandd specimes pecimenn lighlightt graygr...-.. MediuIIodiumm grainedgrained,, massiv_sivae texturetexture.. RoundedRounded claclayy pebblepebble.s araree scattereI catteredd throughout ththee asampleampl e..

MineralMinerallJs t

PrimarPr1m&r7y EaaentialEssential

volcanivolcanicc glasgle..s 6C60%$

plagioelasplagioclaeoe 3%J%

orthoclasorthoclasee 1%1%

quartquart.z 1%1% 5577

AccessorAcce ••o ryy

biotitbiotitee 1%1% magnetit_etitee 1%1%

SecondarSecondar.ry AlterationAlteration

claclOTy mineralmineralas k%4%

IntroduceIntroducedd

calcitcalcitee 30$

TextureTexture:;

PyroclasticPyrocluticj; holohyalineholohyaline;; anandd pumiceouapumiceous. CrystalCr;retalas araree 11

ttoo 2 mmm .. inin diameterdiameter,, araree subhedral8ubhed.ral,, anandd areare equid1menaional.equidimensional.

SpecialSpecial l.aturesfeatures::

ThThee gglasl ....s fragmentt_ntas araree primarilprimarilyy pumicepumice,, lIithwith eloelongatengatedd

vesiclesv.alelM.. MusiveMassive calcitcalcit.e tillafills vesicleveaieless andand fractures.fractures.

No preferrepreferredd orientationaorientations oobservedbeerv.d..

ObeervatlonaObservations s:

Thi.This specimenspecimen iais oIu.iriedclassified asas •a pumice.pumice. MechanicalMechanical trana­trans­

pert.ationportation atterafter thethe orioriginaginall ..ashfalhtall l 18is notnot apparent.apparent. Weath­Weath­

eringering baahas beeboenn alislightght,, lIithwith verveqy littlelittle dev1trit1oationdevitrification otof

ththoe volcanicvolcanic glue.glass.

SamSamplplee collectedcollected tromfrom thothe NNorwooorwoodd formationformation approx1matelTapproximately ~£ milemile eeas ..t t otof UtahUtah HiHighwaghwOTy 6666,, alongalong thothe roadroad lIh1chwhich leadaleads upup NNoror­­ woodwood Canyon,Canyon, nearnear Porterville,Porterville, Utah.Utah. SampleSample vuwas takentaken fromfrom aboutabout

7575 teetfeet bolo"below thethe toptop otof thothe tormation.formation. HandHand specimenspecimen lightlight ggrarOTy toto ggrarayy brollll.brown. Ext.remelyExtremely finefine ggrainedrained,, massivemassive texture.texture. 58

MinMineralserala,:

PrimaPrimarryy EoeentialEssential

volcanicvolcanic gglaslas.s 2525%$

quart.quartz 5%5$

plagioelasplsgioclasee 11%$

orthoolue©rthoclase 1%1$

ACCAccessor ••• Oryy

biotitbiotitee 11%$

magnetitemagnetite 1%1$

claclOTy m1neralaminerals 3030%$

SecondarSecondar.yy AlteratioAlterationn

clOTclay mineralmineralas 1515%$

hematithomatitee 0.0.55%$

limonitlimonitee 0.50.5%$

IntroduceIntroducedd

calcitcalcitee 20$

TextureTexture::

PyroclasticPyroolastic;; vitrophyricvitrophyric;; anandd aphaniticaphanitio.. CrystalCryot&l&s .usubhedrabhodrall

ttoo anhedralanhedral..

SpeciaSpeciall teatures:features:

ThThee volcanivoloanicc glasglases consistcanoutes ooff shardeh&rd8s anandd pumicpumicee (abou(aboutt 80%80$

shardsehard.,, 2020%$ pumicepumice,, ooff ththee totatotall glass)glase).. ThThee glasglas.s frog­frag­

mentmentas araree delicatdelicatee anandd unbroken\Ulbroken.. CalcitCalcitee occuroccurss aass a tinefine

grainegrainedd aggregataggregatee cementcement,, fillintillingg fracturefracturess and veelclee.vesicles. 59

Obeervationa;Observationss

Thi••s specimepecimen n isis olae.classifieiliodd aus a vitricc tuU,tuff, hhavinavingg thethe

compolitioncomposition ofof a quartz. latlatitei te.. MechanicaKochanicall ttransportatior ansportationn aftorafter

thethe originaorig1n&ll uh!&llashfall 10is notnot indicated.indicated. WeatherinWeatheringg otof thilthis aam­sam­

plpIee hashas beebeen extextensive.naive ..

SSamplampl e collectedd fromfrom the NorwooNorwoodd formatiotormationn approx1m&to~approximately ~£ mimillee outeast ofof UtaUtahh HighwaHighw;yy 6666,, aloalonngg tht he roodroad 1IhJ.chwhich loodoleads up NorwoodNorwood C&n,yon,Canyon, neanear PortervillePorterville,, UUtahtah., SSamplamplee vaawas taket akenn fromfrom abouaboutt 115500 t.etfeet bbeloeloww ththoe topp of ththee formationfo_tion.. HanHandd specimeapecimenn lighlightt gragrqy brownbro"". CoConglomngl om­­ eratiorati cc texttextureure.. VerVOI7y finfinee ggrainerainedd matrimatrixx witwith!h £ toto ,J inincch diameterdiameter pebblepebbl.. s otof dadarrkk gragrqy ttoo purplpurPloe quartzitequart.ite.. RoundeRoundedd clqclay pebblepebbl.. s didisa­­ seminateaeminatedd throughouthroughoutt theo specimenapecimen.. A fewfow,, scattereIcatterodd biotitebiotite flake.flakes araree visiblv1eibloe ttoo ththee nakenakedd eye.,.... SamplSamplee studieItudiedd iinn ththee cI'WIcrushehedd .statet ate..

MineralsIdnerals::

volcaniTolcanicc gglaslues

quartquart.z

plagioelasplagioclaeee

biotitbiotitee

magnetitmagnotitoe

claclqy minera10minerals

IndeIndexx ootf refractioretraotionn ootf ththee gglass~::

betweeb.tvoenn 1.51.511 anandd 1.1.5522

SamplSamplee collectecolloctedd frotromm ththee NorwooNorwoodd formatioformationn approximatelapprox1m&to~y £! milemile wesveett oofr PetersonPet. reon,, UtahUtah,, alonalongg larglargee irrigatioirrigationn canalcanal.. SpecimeSpecimenn takentaken 6600 frofromm ththee middlmiddlee portioportionn ofof ththee exposure.exposure. HanHandd specimespecimenn lighlightt £,n:ygray toto graygray.. VerVeryy finfinee grai11ed,grained, massivIT..assivl:'e texturetexture.. FeFeww scatteredscattered darkdark mineralaminerals araree barelbarelyy visiblvisiblee witwithh ..a hanhandd lena.lens.

MineralsMinerala::

PrimaryPrimary EssentialEssential

volcanivolcanicc glassglass 50$

quartquartss 12%

plafioclaspl&'sioclasee 2%

AccessorAceeasol->yy

biotitbiotitee 1%

magnetitemagnetite 1%

claclayy mineralsminerals 10%10$

SecondarSeoondaryy A.lterationAlteration

hematithematitee 1%lS

limonitlimonitee 1%1$

claolayy mineralr;:iine ralas 22%22$

Texture:Texture:

PyroclasticP"rJl"OclMtic;; v1trophyric;vitrophyric; anandd aphanitic.aphanitic. CrystalCrystalss areare

anhedral.anhedral.

SpeciaSpeci~ll features:features:

ThThee volcanivolcanicc glassglass iiss whollwhollyy comprisecomprisedd ooi.'f shards.shards. TheThe

majoritmajorityy ooff ththee claclayy mineralmineralss appearappear toto bbee thethe resulresultt ofof

devitriflcationdevitrification ofof ththee glassgluB,, althoughalthough a smalsmalll portionportion

appearsappears ttoo bbee a resulresultt ofof alterationalteration ooff feldsparsfeldspars andand 6611

biotibiotitet o..

Oba.rvatioll8Observations :s

Th1aThis specimespecimen 18is aonaideredconsidered a vitrio,vitric, oror weldeweldedd,, tufftuff,,

havinghaving a cocompositiompoaitionn otof a rhyodacite•. MocbMechanicaanic&ll tranaportatiotransportationn

atterafter thethe orioriginaginall uht&llashfall 10is notnot apparent.apparent. ConoolldatioConsolidation iois

due toto silicification,silicification, oror "Wa"weldingl ding"" ofof thethe gglasslaaa.. ExtenaiveExtensive dede­­

vitrifvitrificatioioationn otf tthhee vvolcaniolcanicc glglas.. se 18is evident.evident.

SampleSample collectcollecteedd trofromm thethe NNorwoooMO>OC1d !o_tionformation approx:t.mr.teapproximatellry i£ mimilloe wa.twest ofof PetereoPetersonn,, utUtahah,, aloalonngg lalargrge irriirrigatiogationn canal.canal cut. SSpecimepecimenn takentaken fromm thethe bu.base otof thethe u.po8ure.exposure. HandHand specimen Terrvery lilighght ggrarayy toto white.white. ExtremelyExtremely fintinee ggrainedrained,, mullivamassive texttextureure.. A vvere ryy tewfew biobio­­ titotite graingr&1nos areare v1eiblovisible witldthh a& handhand lensl ens.. sampleSample iois ve17very brittlbrittlee andand breakbreakas intintoo conchoidalconchoidal fracturefracturess..

MineralsMinerala::

PrimarPrima17y EssentiaEooenti&ll

volcanivolcanicc gl&&oglass 85%

quartquartzz 1%

Accessor.1008811017y

magnetitmagnetitee 1%

SecondarSecondaryy AlteratioAlterationn

claclayy minoralominerals 13%13%

TextureTexture::

PyroclasticPyrocluticl; holohyalineholohy&linel; vitrophyricvitrophyricl; anandd aphanitic.aphanitic 62

SpecialSpecial features:features!

ShardsShards areare abundant,abundant, comprisingcomprising overover one-halfone-half ofof thethe volcanicvolcanic

glass.glass. FracturesFractures areare filledfilled withwith opaqueopaque clayclay minerals.minerals.

Observations .:

ThisThis specimenspecimen isis Classified.classified asas a vivitritric c tuff.tuff. MechanicalMechanical

transportationtransportation afterafter thethe originaloriginal ashfallashfall isis notnot apparent.apparent. TheThe

puritypurity ofof thethe ash,ash, alongalong withwith ththee extremeextreme finefine grained.grained texture,texture,

suggestssuggests possiblepossible eolianeolian sortingsorting atat somesome distancedistance fromfrom thethe parentparent

magma.magma.

SampleSample colleotedcollected fromfrom thethe NorwoodNorwood formationformation approximatelyapproximately 1,5001,500 feetfeet northnorth ofof thethe junctiojunctionn ofof U.U. S.S* AlteroateAlternate HighwayHighway 189189 andand UtahUtah

HighwaHighwayy 196196 nortnorthh ofof Peoa,Peoa, Utahutah.. SpecimenSpecimen taketakenn frofromm exposuresexposures onon thethe easeastt sideside otof thethe road,road, fromfrom a dardarkk colorecoloredd volcanivolcanicc bebedd overlyingoverlying lightlight graygray tuffstuffs.. HandHand specimenspecimen dardarkk gray,gray, mottledmottled.. .MediumMedium ttoo coarsecoarse grainedgrained,, prophyriticprophyritic texture.texture. AbundanAbundantt phenocrystphenocrystss ofof plagioclase,plagioelase, hornblende,hornblende, anandd biotitebiotite,, withwith a smalsmalll amounamountt ofof quartzquartz.. SampleSample studiestudiedd iinn ththee crushecrushedd state.state*

MineralsMinerals::

plagioelasplagioclasee

quartquartzz

biotitbiotitee

hornblendhornblendee

volcanivolcanicc glassglass

claclayy mineralsminerals 63

calcitecalcite

magnetitemagnetite

hematitehematite

liJoonilimonittee

IndeIndexx ofof retractionrefraction ootf ththee glueglass t.

betweebetwoenn 1.1.5522 anandd 11.5.533

SamplSamplee colleccollectetedd frotromm ththee NorwooNorwoodd formatformatioi onn approximatelyapproximately 1.1,505000 feereett northnorth otof ththee junctioj unctionn ooff U. SS.. Alternatllten>atee HighwaHighw;yy 189189 andand UtahUtah

HighwaH1ghll'Q'y 191966 nortnorthh ootf Peo.Peoa,J Utah. SpecimeSpecimenn taketakenn fromm expo.exposureuresa onon thethe easeutt lsididee ooff the roadroad,, abouaboutt 60 feefeet belobel oww ththee toptop otof thethe tutttuff­­ aceou&080118s strata.tnt... HanHandd specimelpecimenn gragrqy toto gragra;yy brollO.brown. VerVeryy fin.fine ggrainedrained,, massiv_aiT.e texturetextuno.. RoundeRoundedd claclqy pebblepebbleas disseminatedieaeminatedd throughouthroughoutt thethe specimens pecimen..

MinMlneral.ae rale ::

PrimarPrimarry EssentialEssential

volcanivolcanicc glasgluas 3535%$

plagioelasplagiocl.. ee 5%$

quartquart.z 4%4$

AccessorAcces.oryy

biotitbiotitee 1%1$

magnetitmagnetitee 11%$

claclqy mineralmineralas 15%$

SecondarSecondaryy AlteratioAlteration

claclqy mineralmineralas 1199%$ 6464

IntroducedIntroduced

calcitecalcite 20%20$

Textures,

PyroclasticI7roclutic;; vivitrophyrict roJ>hTric;; anandd porphyritic.porphyritic. CCrystalrylltalas

euhodreuhedraall toto esubhedralubhodral..

SpecialSpecial features:featuress

TheThe volcanivolcanicc gglaslaaas iais comprisecomprisedd ooff aboabouutt one-halone-haltf angulangulaarr

fragmentsfragment.,, two-fiftht wo-fifthss shards,, andand one-tenthone-tenth pumicpumicee frag­frag­

mentsments . AJ. larglargee portportioionn ofof tht hoe glueglass hahu s beeboonn devitritidevitrifieded ..

FinFinee grainegrainedd calcitcalcitee rifilllles fracturestracturu,, vesiclesveaiel.. , , anandd intinterer­­

stices.ti c ....

ObservationsOba.rvatlonas t

ThiThUs specimespecimenn i1s classifiecl... ified. d a&IIs a• vitrivitricc tufftuft.. A feteww ootf

ththee graingrairuls araree welwelll roundedrounded,, suggestins uggestingg somaomee mechanicamechanicall transtrans­­

portatioportationn afterr ththee originaoriginall ashfallu hfall.. ThThee porphyritipol'J'l\yriticc texttextururee

ooff thith1as sampleaampl e,, when comparecomparedd ttoo ththee fine' grainegrainedd texturtexturee of

ththee tuftuftf samples ampl ••s ttoo nortnorthh and eastsut,, suggestauggslltes thathatt thithias lspecimepecimenn

mamqy havhavee beeb.enn depositedeJX)81tedd closecloser ttoo ththee sourcloure.e venventt (Willian::.,(Williams,

TurnerTumer,, anandd GilbertGilbort,, 19551955;; pp.. 151)151)..

SamplSamplee collectecolleot edd fror~m ththee NorwooNorwoodd formatioformationn approximatelapproximatelyy 1,1,505000 feefHtt nortnorthh of ththee junctiojunctionn ooff UU.. SS.. Alternatliternatee HighwaIIighwa;ry 181899 anandd UtUtaahh

Highwa~y 191966 nortnorthh ooff PeoaPeo.,, UtahUtah.. SpecimeSpecimenn taketakenn frofromm exposureexposuress on ththoe easoutt sidaidee of ththoe roadroad,, abouaboutt 101000 feefeott beloboloww ththoe to topp ooff ththoe ttuffuff­­ aceouaceouss stratastrata.. HanHandd specimespecimenn gragra;yy ttoo gragrayy brownbrow.. VerVeryy finfin,e ggrainedrained,, 6565 musivemassive texture.texture* RoundedRounded pebble.pebbles ofof clqclay abundant.abundant*

HineraJ.a:Minerals $

Pr1rn&ryPrimary :E.eentlLlEssential

volconicvolcanic glulglass 35%35$

plagioelasplagiocl...e 1100%$

quartzz 2%2$

AccessorAcce.8o:ryy

magnemagnetittitee 1%1$

biotitbiotitee 1%1$

clo;yclay mineralminerelos 30%30$

SecondarSecondar,ry AlteratioAlterationn

claclo;yy mineralmineroles 15%15$

hematithematitee 1$

limonitlimonitee 1$

IntroduceIntroducedd

calcitcalcitee 4%4$

TextureTexture,s

PyroclasticI7rcclO8tic;; vitrophyricvitrcphyric;; anandd porphyriticporphyritic.. PhenocrystPbenocryates areare

abouaboutt 1 ttoo 5 mm..... iinn diameterdi_t.r.. CrystalCryatalos araree subhedralubhedrall toto

anhedralanhedral.*

SpeciaSpeciall features:featuress

ThTh.e volcanivolconicc glasgluas consistCOMiates primarilprimarilyy ooff pumicpumicee fragmente.fragments,

witwithh a fef."w shardsohardl.. Mas~ott ooff ththoe glasga ..s iias devitrifleddevitri!iod.. Fin.Fine

grainegrainedd calcitcalcitee filltillss vesicleveeicleas anandd intereticinterstices••• . 66

ObObservation© •• rY'atiol'l8 !:

ThisThis .specimepoc1menn 10is claa.itiodclassified ..as a pumice.pumice. MechaniMechanicacall tr&!llltrans­­

portationportation attafteerr thothe originaloriginal ..ashfalM alll 10is nott aapparentpparent.. No prepre­­

terredferred orieorientationntatioDIIs oror flowflow .tstructureructurws oobservedbserved..

TheThe petropetrographigraphico analya..analyses ofof Fowk..Fowkes andand NNorwooorwoodd samplel ampl..s reveareveall .eseveraverall o1m1l&r1t1similaritie.. s andand didissimilaritieaaiJnil&r1ties. bbetweeotwo.n thethe t..,two tormat10ns.formations. TheThe momosatt cbaractcharacteristier1.8t1cc featfeatururee otof thethe lsampleampl ••s ststudieudiedd 18is thethe highhigh contentcontent otof vovoll­­ oaniocanic gglasslao.,, part1oul&rl,yparticularly inin ththee fonnform ofof .hardashards andand pumice. lMineral!1neralas pprere­­ senl entt inIn thethe samplelaI!lplees fromfrom botbothh fformationOI1llat1onas areare vvere X"Y'y nnearlearlyy thethe samel ame,, althoalthougughh thothe relat1verelative quant1t1quantitie.. s otof 1n:Iividualindividual m1nomineralralas vvaryar;y. ThThee 1n:Iiindicec ..s ofof rore­­ fract10fractionn otof thethe volcanicvolcanic glasglaoas containeconta1nodd inin bothboth ththee FFowkeollk.. s andand NNorwooorwoodd fformationo_tionss areare verver;yy .War,similar, beingbeing bot.enbetween 1.1.5511 andand 11.52. 52.. ThiThi.s 1n:Iicateindicate.s glao.glass ofof approximatel.ppro:dm&tol,yy 67%67$ .silic1lic.a (Williams(Willi_,, Tumer,Turner, anandd Gilbert,, 11955955:; pp.. 28,28, ffigig.. 7)7)..

VolcanicVolcanic glao.glass constituteconsti tute.s abouaboutt 212l%$ (average(avorago)) otof ththee FowkeFollk.. s format1formation0n,, andand abouaboutt 4848%$ (average(avorage)) ooff ththee NorwooNorwoodd formationfomation.. FeldsparsFeldoparo,, quartzquart.,, andand heav_ .".y mineralminoralos appeaappoarr ttoo be. mucJmlchh mormoree abundanabWldantt iinn ththoe FowkeFollk ..s formatioformationn thanthan inin ththoe NorwooNorwoodd fo_t1on.formation.

InvestigationInv.. tlgatlona s oorf thit hinn sectionaectioDils indicatindicatee thathatt thertheree habaas beebeen veverr,yy littll1ttlee mechanicamechanicall transportatiotranoportat1onn of ththee materiamatoriall afteafterr ththoe originaorJ.g1nall depodepo­­ sitiolitionn ooff thee volcanivolcanicc ashu h.. FielFieldd studies.tudi_,, howeverhowever,, giv givee stron. t rongg evidenceevidence ooff fluviafluviall anandd lacustrinlacuatrinee processeprocessess iinn botbothh ththee FowkeFowk ••s anandd NorwooNonlOOdd toforr­­ mationsmationa . ProminenProminentt lenticulalenticularr cross-laminationcl"OSa-1am1nation,, coarscoanae conglomeratconglomeratee lenaea,lenses, 67 anandd fresh-watefresh-waterr limestonlimtetonee bedbedss araree common iinn bothh formationformat ionss (se(seee figfigureuress

6 amand 7)7).* ThThee writerwriter feeltoelas thatthat ththee broadebroaderr evidencevidencee frotromm tht he fieltioldd "'1'­war­ rantrant.s ththee conclusioconclusionn thathat fluviafluviall anandd lacustrinlacuatrinee processeproc.aea:s havhavee playeplayedd anan importanimport.antt rolrolee iinn ththee presenpresentt distributiondistribution anandd lithologiel1thologies. oatf thee FowkesFowkes anandd NorwooNorwodd tonnatlone.formations.

CorrelatioCorrelationn

ThThee compositiocompositionn ooff ththee FowkeFowk ••s formationformation i1.s cloe8close ttoo thathatt ofof a rhyorhyo­- daeitedacite,, whereawhere ..s ththee cocompositiompositionn ofof tthhee NorwooNorwoodd tuftuftf 1.is cl08.close ttoo that hat of a latitlatltee or quartz. latitelatlte.. ThThee range iinn compositioncomposition,, howeverhonver,, aappearppearss too bbe nearlynearly asas ggreareatt withiwithinn eacheach formatioformationn &IIas betweebetwenn thethe twotwo formations.formations.

PalPaleontologicaeontologicall evidenceevidence frofromm thethe Fowkes andand NorwooNorwoodd formaformationt ionss ssugug­­ g_tgest a& cloeeclose timetime equivalenequivalencece.* FreFresh-wateeh-waterr ggastropodu tropodss fromm the FFowkeowkess fo~tionformation havehave beenbeen ..assignesi gnedd toto thethe upperupper EocensEocene b;ry GGaziuinn (1(1959)959) , anendd b;rby ththoe writerwriter ((se ••e pagepog.. s 1,242 amand 4343)).. VertebrateVertebrate remainoremains trofromm tthheo NNorwooorwoodd formationformation havehave beenbeen identifieidentifiedd a&IIs uppeupperr EocenEocenee tOnDIforms ((GazinGuin, 11959959;; EaEardleyrdley,,

POnlonalpersonal communication).communication).

TheThe Fovk..Fowkes anandd NorwoodNorwood fonnatlonaformations occoccupupyy thethe ssamamee sstratigraphitratigraphicC 1nin­­ terralterval andand a1'8are ofof nenearlarl;ry identicalidentical l1tho10lithologiesgi ....

ExpoourExposure.. s of thsthe NNorwooorwoodd tufttuff exhibitexhibit incroincreasingl.. 1ngl;r y finefine ggrainerainedd textex­­ tureture fromm sosoututhh toto north.north. TexturesTextures of thethe FFowkeowkess asampleampleas correscorresponpondd cl.oecloselelyy withwith thethe texturestextures ofof thethe NNorwooo rwood.d ,amsampleple.s takentaken fromm PorlerrlllePorterville andand Peteraon,Peterson, UUtahtah.. ThUThis laterallateral texturetexture ggradatioradationn 1.is cconsistenOll8utent witwithh thethe theorytheory thatthat thethe ParkPark City volcanicvolcanic field,field, toto thethe sosouthwestuth_at., maymay bebe thethe .osourcureee areaarea ofof bothboth thethe Fowke ..s andand NorwoodNorwood (Eardley,(Eardley, penopersonanall cocomm­­

IIIWl1c.tion).munication). \

FigurFiguree 6. FowkeFowkess formatioformationn outcrooutcropp iinn WhitneWhitneyy Canyon, showinshowingg localocall conglomerateconglomerate lenselensess anandd slighslightt cross-laminatiocross- laminationn (arrow)(arrow).. r.:..,.. .. --. --- , --. - .. .. - 1.- • • ." - • -, -- -• • • -

FigureFigure 7-. FowkeFowkess formatioformationn outcropoutcrop inin WhitneWhitneyy Canyon, showingshowing locallocal conglomerateconglomerate lenseslenses . 7700

ParParkk City volcanicvolcanicos araree fountoUrJdd overlyinoverl;ringg NorwooNonooodd tuftuftf iinn ththee vicinityvicinity

Ooff PeoaPeoa,, Utahutah.. ThThee mineraminerall compositiocompceltlonn ooff botbothh ththee ParParkk CitCityy vovolcaniclcanicss anandd ththee NorwooNorwood.d tufftuff,, iinn thithiss localityloc ~ alitY,J araree ververyy similar. 1m1lar.. TherTheree .appearppeares ttoo bebe a closcloa.e ulociatlonassociation ooff tht he twtwoo formationstormationa, J bubutt ththee trutruee timtimee anandd origioriginn relationshiprolotiollllhipos araree nonott Imknowo ...n anandd musmustt remairemainn opeopenn ttoo quootion.question.

Conclusions

InIn rtewview of thethe evidence, thelthe writer feelraGas thathatt correlationn ootf thethe

Fowk_Fowkes fonnatiformatioonn with ththoe NorwooNo_cdd l formatiotonnationn i1&s justifiablejuat1tiohlo., thi'l'h1as corro-corre­ lat1.onlation woulwouldd nenecessitatces.itatee thethe discontinuanoediscontinuance ooff us\188e ooff ththee namnamee "NorwoodNorwoodn11 iinn preferencpreferencee ttoo theo .,.,..name "Fonee","Fowkes", aU s suggesteougg ..ted d bbyy EardleEardle;yy (1959)(1959 ), thothe nam.,.,..e "Ponoo""Fowkes" havinhavingg prioritypriority (V"atc(Veatchh,, 11907)907)..

Measured section

ThiThicknesckneeas ofof tthhe FollkFowke ••s to:nIlat1onformation i18s nonott everywhereve:r;ywheree equal,, duduee toto

.tructuralstructural relationarelations andand erosion.erosion. ThThee followinfollowingg ••sectioction n wa....s measuremeuuredd inin l.et10section 33 ,, T.T. 17 NN..,, R.R. 120120 W.v.:s

lliuviumAlluvium FowkesFowkes F.etFeet

CoveredCovered elopeslope;; Ughtlight gray'gray claystonclayatonee float;float; cocontainnt&i.nlls tragmantlllfragments ofof crysta.l.l1ne,crystalline, ~t.white l1me8ton...... limestone. •••• 8)83 DecomposedDecomposed tuft;tuff; lilighghtt gra;rgray toto gragra;ry bbrownrolln; elopeslope fOl1Dllrformer...... ••.**....,••• ••••••, ...... * •••••••••« • 9 FFresreeh water limestone;limestone; mua1.vemassive crystalline;crystalline; Ulighghtt gra;rgray toto 1Ihl.t.ewhite;; weatherw.theros intointo small,small, angularangular trasmenta...... fragments 22 DeDecomposecompoaedd volcanicvolcanic uh;ash; dark:dark gray;gray; containscontains lomesome lalargrgee tufttuff tragmentl;fragments; elopeslope tormer...... former...... 9 7711

TufTuft;f j grag rayy ttoo gragrqy brownbrown;; ea.lt-and-pesalt-and-peppepperr appearanceappearance;; slighaUghtt lenticulal enticularr 01'0."­cross- laminationlamination;; containcontainss inclusioninclusionss otof whitwhit,e claystonc~tonee or mudstone.mudstone...... • ...... 8 SiltstonSiltstonee anandd claystoneclayatonei; gragr.ry ttoo white; slope-formerelope-tormer; ; floafloatt containcontainss amallsmall fragmentfragmentss ootf crystallincr.ratallinee limeetonelimestone and tuft...... 59 and tuff..«.««..•».«».*«»..««..«».....««....«.««« 59 Total expoeed Fowke. tor.mat1on...... 170 Total exposed Fowkes formation...... 170 72

PERI- COALVILLE EVA NSTON CENTRAL 00 EPOCH OR STAGE GROU P OR SER IES ARE A, UTAH AREA, WYO. UINTA CO' WYO. (W illiam s1- Modseti (BurgerI Duche snian Ulntan Eocene Fowkes fm . 7. - Bridgerian Areen ridQer! ? Ri.... er >- Wosatchian Kn ight 1m. Wa satch f m. 0. Knight fm. '"- Clorkfork lon rtf / ffff f 0 I- ~ Fowkes fm. " Til10nion u '"w Po leocene 0 I- Torrejonion -~ Evans ton fm. 0 Al my fm. Oro(J onion ;,: Puercon ~ Evanston fm. ? Danian Hell Creek E -• ~ > Lozeort SI. Moestrichthion FOK Hi lls 0 ~ member <> ~ Echo Conyon " 0 ~ D conOI .

0 ~ Pierre 0 Hilli ard 1m . ::> Companion '"0 -~ w 0 u " Eoole I- w" Telegraph Creek Santonian u 7 '" Wonshi p 1m . Niobrara Con iacian <> w ~ '" 0 .. ~ ' / ZLfL/UL .. ~ Kemmerer cool ::> Carlile £ Turon ian ~ 0 Frontier fm. .~ Oyster Ridoe 55 ~ ~ 0 0 Belle Fourche ~ 51" ... 0 Cenomanian u Mowry Aspen fm. Aspen fm.

Bear River 1m. Bear River fm.

Albion '"::> Upper Upper @ Gannett group Gannet t group u <> Ke lvi n fm. und iff. undiff. ;'! ~ Aptian 0 w ~ cr u '" ? ? cr - ? Borremian -•~ w ~ ;,: 0 0 Hautervorian to Ephraim cong l. -' (covered) Valanginian Berrias ian ? ?

FigurFiguree 8 . StratigraphicStratigraphic CorrelationCorrelation CCharhartt NENE UTAHUTAH EVANSTON,EVANSTON, WYWYOO.. CENTRACENTRALL UINTUINTAA CO., WYOWYO..

Pork City volcanics Norwood fm . Fowkes tm. BridOer fm. 1 Wasatch fm . Wasotch fm. Evanston fm. Adaville fm . Ech o Con yo n conglomerate 1.-- 7-_ _-._-_ ------Wonsh ip 1m. - - Frontier fm. As~n fm.

reuSS f m. ree"" fm. Twin C

FigurFiguree 9 . IdealizeIdealizedd cross-sectiocross-sectionn frofromm northeasternortheastemn UtaUtahh ttoo centracentrall UintUintaa County,, WyomingWyoming,, showingshowing interpreteinterpretedd stratigraphistratigraphicc relationshiprelationshipss (thicknesse(thicknessess anandd structurestructuress araree nonott necessarilynecessarily accuratelaccuratelyy represented)represented).. STRICTURESTRUCTURE

FaultsFaults

NormaNormall faultsfaults transecttransect thethe report.report areaarea inin a north-trending,north-trending, parallelparallel anandd enen echelonechelon pattern.pattern. Two majormajor faultsfaults fonnform ththee boundariesboundaries ofof thethe BearBear

RiverRiver Valley,Valley, fromfrom EvanstonEvanston northnorth toto thethe NarrowsNarrows., ThThee valleyvalley isis a grabengraben betweenbetween themthem (Earoley,(Eardley, 1959).1959). EscarpmentsEscarpments markmark thethe tracetrace ofof thesethese twotwo majomajorr faults.faults.

TheThe faultfault alonalongg ththee eastereasternn margimarginn ofof ththee reporreportt areareaa isis callecalledd thethe

AcockAcookss FaulFa.ultt (Veatch,(Veatch, 1907),1907), seesee GeologicGeologic Hap,Map, platplatee 22.. ComplexlyComplexly foldedfolded andand faultedfaulted LowerLower CretaceousCretaceous GannettGannett stratastrata fonnform thethe east,east, footwallfootwall,, blockblock ofof AcockAoockss FaultFault., ThThee westwest,, hanginhangingg wallwall,, blocblockk isis composedcomposed ooff thethe easteast dippindippingg WasatchWasatch,, BridgeBridgerr (?)(?),, anandd FowkeFowkess formationsfonnationa.. MaximuMaxImumm vert.icalvertical displacemendisplacementt alonalongg ththee AcockAcockss FaulFaultt iinn thithiss areareaa iiss approximatelapproximatelyy .3,.3003,300 ttoo 3,50.3.5000 feet.feet,

A majomajorr normanormal.l faulfaultt truncatetruncatess ththee nosnosee ooff AlkalAlkalii SynclinSynclinee alonalongg itaits southwessouthwestt marginmargin.. ThThee faulfaultt lieUess betweebetweenn ththee AcockAoockss FaulFaultt anandd ththee easteast faulfaultt ooff ththee BeaBearr RiveRiverr ValleValleyy grabegrabenn (se(seee platplatee 2)2)., ThThee faulfaultt alonalongg thethe southwessouthwestt margimarginn ooff AlkalAlkalii SynclinSynclinee mergemergess witwithh ththee easeastt riveriverr vallevalleyy faultfault alonalongg ththee west-facinwest-facingg slopslopee ooff Narrows HillHill.. ThThee faulfaultt borderborderss AlkaliAlkali

SynclinSynclinee oonn ththee west.west.

7744 7755

BridgeBridgorr (?(1)) bedbodas havhavee beebeonn broughbroughtt intintoo contacoontactt witldthh ththee GannettGannett grougroupp alonalongg ththee faulfaultt whicwhichh eutcut.s ththae AlkalAlkalii SynclinSynollruoe noseno.... A-' narrow,narrow, shallo.halloww topographitopographicc trougtroughh separate••parat .. s ththee BridgeBridgorr (?(1)) anandd GannetGannettt etrot.,strata, markinmarkingg ththee faulfaultt tracetrace.. MaximuIIaxI.mumm verticaverticall displacemendieplacomontt alonalongg ththoe faultfault

10is abouaboutt 3,353,3500 f.ot.feet.

ThThee magnitudemagnitud.. s anandd trutruoe dipdipes ooff ththee grabeg rab~nn faultfaultes alonalongg tht hoe rivorriver valley araree obscureobacure.. EscarpmentEacarpnentss oonn eaceachh .ideside otof ththee riverriver vallev&lleyy areare uphelupheldd bbTy WasatcWooatchh anandd FowkeFClIk ...s stratatrota. . ThoThe valloTvalley floofloorr 10is coveredd b;rby thickthick alluviaalluviall dopoeita.deposits.

AnotheAnothorr larglargee normanormall faulfaultt wa_ s mappedmapped inin thothe southereouthomn parpartt ooff thethe reportreport areaaroa.. ThThoe faultfault .triko.strikes northnorth,, extendingextending fromfrom thothe vicinityT ofof ShelSholll HolloHolloww northnorth toto thothe moutlIIOuthh ofof SSpringpr1ngas Canyo~nn (Veatch(Vo.tch I.fs "Alm;r"Almy fault").fault"). AtAt ththoe lIIOuthmouth ofof ShelSholll HollowHollow,, WuatchWasatch andand FollkoFowke ••s strattrat. a ",etrest inin faultfault oontactcontact ldthwith thethe BoarBear RiverRiver fomationformation ((se ...e figurofigure 10).10). 1Iax1-Maxi­ mumumm verticalvertical displaoementdisplacement 10is approximatol;rapproximately 1,4001,400 toto 1,5001,500 root.feet.

A cocomplemplexx lOnezone orof faultingfaulting occuraoccurs inin thethe mouthmouth otof SpringSprin~s CanyoCanyonn..

A faultfault oonezone trondstrends north""eterl;rnorthwesterly alongalong thethe lengthlength otof SpringeSprings ~nCanyon,, anandd appearsappears toto int.nectintersect thethe ShallShell HollowHollow fault,fault, mentionedmentioned above,above, inin thethe mouthmouth ofof thethe ce.nyon.canyon. RelationsRelations areare oobscurbscuree inin thiathis localitlocalityy._ Noo didirecrectt evidenceevidence lfUwas fO\U1dfound wehwhich wuldwould claritclarifyy thethe problem.problem. BBeyoneyondd thethe mouthmouth otof

Spr.1.Springngas CalQ'on,Canyon, thethe faultsfaults areare ccovereoveredd byby FowkFowke ••s depoeit8.deposits•

AnotherAnother majormajor nonnalnormal faultfault 18is 8Xprells8dexpressed byby a prominentprominent ..escarpmen carp:nentt

&longalong thethe weetemwestern marginmargin ofof thethe aarereaa inin thethe viCinityvicinity atof A.l.m;y.Almy. TheThe FowkesFowkes formationformation huhas beenbeen loweredlowered aloalonngg thethe taultfault intointo contactcontact withwith thethe lowelowerr Shell Hollo ...

FigurFiguree 1010.. VieVieww northeastwarnortheastwardd frofromm ththee southersouthemn extremitextremityy ooff ththee areaarea, J showinshowingg ththee faulfaultt tractracee alonalongg ththee moutmouthh ooff ShelShe1ll Hollow.. 7777

bedbodas ooff ththoe WasatcWaaatohh fo_tion.formation* BotBothh formationfo_tion.s didipp slightl" Ughtlyy wes",,"tt (2 toto

5 degreudegrees)) . TheThe WasatcW9aatchh fomationformation appeanappears toto rearest conformably"conformably upouponn thethe

FowkesFowkes , whevbenn vieweviewedd frofrom.m a distancedi.tance.. ThiThias apparenapparentt relationshirelationshipp ledled

VeatcVsatchh (1907(1907)) ttoo tht hee erroneousrroneouss subdivisiosubdivisionn ooff ththee "Wasatc"Wuatchh ggroup"rouptt,, withwith

"Knight"Knight"" ,..Itingresting conformabloo:1!onnablyy upouponn FowkeFollk..s (se(8O.e figurfiguree 11).11).

LatLatee EocenEooenee fonnationaformations araree involveinvolvedd iinn ththee notmal.normal faultinf aultingg ooff thethe

areaarea nnortorth ooff EvanstonEvanoton,, WyomingWyoming.. EardleEardleyy (1(1959959)) suggestougg.. ts s ththoe probabilityprobability

that thethe faultinfaultingg originateoriginatedd iinn prepre-Fowke- Fowk.. s time, witwithh movemenJOOvomentt alonalongg thethe

fault.faults cocontinuinnt inuingg intintoo poat-Fowkpost-Fowke•• s timtimee Crera(refer ttoo aeosectiotionn oonn GeologicGeologic

lI1atoHistory)ry) .•

OOrigiriginn atof thethe no:rm&l.normal faulttaultas inin thithiss areareaa D!.I3"may bbee due ttoo either,either, oror both,both, of thothe following,following:

1.1. LataLate LaramidLaramidee deformationdeformation followingfollowing depositiondeposition otof W&aatchWasatch

clasticelastics•• .

2. saltSalt anticlineanticline developmentdevelopment..

SaltSalt intruaionintrusion (?)(?)

EardloEardley (1(1959959)) diaCualeddiscussed thethe po.sibilitpossibility ofof "altsalt anticlineanticline develop-develop­ mentment inin thethe EvanatonEvanston area,areas

tt'fh"The .stratt nt.a otof tthhee BeBeckwitckwith tonnation,formation, upecla.llyespecially lIbwhereree exposedexposed inin 'everalseveral ofof thethe uptaulttdupfaulted bloblockseb ,j .trikestrike diadiscordantlcordantlyy withwith thethe BBasiuinn andand RangeRange faults.faults• AJ.thoAlthougughh notnot mappedmapped inin detaildetail everywhere, itit aappearppa.,.s endeevidenntt thatthat BeckwithBeckwith stratastrata havehave bbeeeenn defonneddeformed intointo rather esmallmall,, tighttight foldafolds withwith &18"axes trending atat anglangle.. s toto thethe beltbelt ofof faulting.faulting. SSucuch foldingfolding dodoeess notnot characterizecharacterize thethe pprere­- KnightKnight atstructureructurees east.east oror watwest orf thethe taultfault .one.zone. TheThe UtahUtah SoSoutheruthemn wellwell drilleddrilled inin T.T. 6 N.,N., R.R. 8 E.E. encounteredencountered ,

Figure 11. View westward from Almy, showing Fowkes beds in fault contact with Wasatch strata. 7979

considera.bleconsiderable saltsalt iinn ththee Beckwith,Beckwith, andand thisthis plupluss thethe discordantdiscordant foldingfolding leadleadss ttoo ththee thoughthoughtt thatthat ththee zonzonee inin pre-Basinpre-Basin andand HangeRange faultingfaulting (pre-late(pre-late EoceneEocene)) maymay havehave beenbeen a saltsalt anticlineanticline typetype ofof structure.structure.

TheThe localocall developmendevelopmentt ooff ththee EvanstoEvanstonn formationformation andand itsits depositiondeposition onon ththee truncatetruncatedd BearBear RiverRiver formation,formation, foundfound nowhernowheree outsideoutside ththee faultfault zonezone,, supportsupport ththee theory.theory.

A conflictconflict inin ththee interpretationinterpretation ofof thethe originorigin ofof ththee normanormall faultsfaults ooff thethe faultfault zonzonee isis evidentevident;; areare theythey strictlystrictly thethe resulresultt ofof saltsalt anticlinanticlinee mechanicmechanioss andand thereforthereforee limitedlimited ttoo ththee superficialsuperficial stratastrata abovabovee thethe mothemotherr salt,salt, oror araree thetheyy ooff BasiBasinn andand RangRangee typetype withwith ththee connotatioconnotationn thathatt thetheyy penetratpenetratee deeplydeeply intointo thethe crustcrust andand araree ooff deep-seateddeep-seated origin?origin? IItt isis difficultdifficult toto findfind e"videnceevidence thathatt bearsbears ononee waWIiYy oror ththee otherother oonn thethe problem.problem."1*

SaltSalt wawass notenotedd inin anan oiloil testestt holholee (Slosson(Slosson andand AssociateAssociatess nono.. 1 Cole)Cole) inin T.T. 1616 N.N.,, RR.. 121121 W.W.,, bbyy SchickSchick (1959,(1959, fig.fig. 3).3). TheThe saltsalt occursoccurs inin thethe

BeckwithBeckwith sequence.sequence.

ComplexComplex structuresstructures inin ththee moutmouthh ooff SpringsSprings CanyonCanyon furtherfurther suggestsuggest saltsalt anticlineanticline structures.structures. SeveralSeveral smallsmall blockblockss ooff WasatcWasatchh and.and FowkeFowkess strata,strata, withwith tumbledtumbled,, chaoticchaotic attitudesattitudes,, occupyoccupy thisthis area.area. ItIt isis notnot cleaclearr whetherwhether thesthesee chaotichaoticc blockBblocks areare relaterelatedd toto ththee convergenceconvergence ofof twtwoo largelarge normalnormal faultsfaults (see(see pagepage 75) ,J oror areare possiblepossible slumpslump featurefeaturess relaterelatedd toto saltsalt move-move­ menta.ments. RelieRelieff iinn thithiss localitylocality isis low.low. TheThe writewriterr thereforthereforee feelsfeels thatthat ththee blockblockss areare probablyprobably nonott landslidlandslidee features.features.

ExposuresExposures ooff BeaBearr RiverRiver stratastrata inin ShellShell HolloHolloww exhibiexhibitt inconsistentinconsistent strikesstrikes andand dipdip9s (see(see plateplate 2)2).. TheThe EvanstonEvanston formationformation progressivelprogressivelyy over-over­ laplapss thethe BearBear RiverRiver bedsbeds toto ththee northnorth ofof ShellShell Hollow.Hollow. StrikesStrikes ofof thethe

EvanstonEvanston bedsbeds rangrangee frofromm slightlyslightly weswestt ooff northnorth inin ShellShell Hollow,Hollow, toto westerlywesterly 80 aloalonngg thothe northnorth facingfacing elosloppee ofof SSpringpringes Can,yonCanyon (eoo(see pplatlatoe 22)).. StrikoeStrikes otof thethe overlyingoverlying WasatchWasatch andand PFowkeowkes tformationOr.mat1OU8s axbibitexhibit &a ssimilaimilarr diredirectionactionall changochange inin thUthis vicinityvicinity..

TheThe limitedlimited laterallateral extentt of tthhee aboabovve atstructuraructurall relarelationshipst1onah1pe J, totogethegether with thethe ccompleomplexx zonezone orof faultifaultinngg inin thethe mouth otof SSpringp~s Canyon,Canyon, ssuggestuggeatas polaiblepossible salt intruaintrusioionn inin this llocalityocality..

FoldFoldas

Veatch (1(190?907) d.describeecribodd and namednamed thothe Alk&l1Alkali SSynclinynclin.e whichwhich 14is •a broad,broad, oopepenn structurestructure,, extendingextending fromm aboutabout 1 milemile soutlouthh ofof thethe NarNarrowrows northwardnorthward fotorr aboutabout 6 mimilesl.l.. TThj18e southweslouthwestt extremity otof AlkalUk&l1i SSynclinynclinee isis includedincluded i n tht hee areaarea ofof thisa report.. NNormaonnall faulfaUltt zonezoneas borderborder thethe ssynclinynclinee on thethe weatwest andand eouthsouthwes... t (se(e ••e platplatoe 22)) ..

EocenEocene aesedimentd.1mentes tillfill ththee centralcentral portion, .. or troughtrough,, ofof ththee ssynclineyncline..

CretaceouCretaclouas andand PaleocenPaleocen.e tonr.atlonaformations (Gannett(Gannett,, BeaBearr RiverRiver,, anandd Evanston)Evanston) areare exposeexpoeadd alonalongg ththee ..westet, , uplifteupilltedd flanflankk ootf ththee synclinesyncline.. StratStrataa onon thethe synclineynclin.e limblimb dipdip approximatelapproximatelyy 1212 ttoo 15 degree deg,..es•• easut t northeut.northeast.

A .mallsmall anticlinaanticlinall foltoldd wawaos mappedmapped on tht hee nortnorthh sidoidee otof ththee moutmout h ofof

WhitneWhitney CanyonCan,yon. ThThee foldfold ieis confineconfinedd ttoo thth.e Wasatc_atooh anandd BridgeBridger (?(7)) tor­for­ mationmaUone.s • ThThee &Xialaxial planplan.e ofof ththoe folfoldd strikeetrikese northeastnorth... t. , limbLimbos didipp approxi­approxi­ matelmatelyy 3 ttoo 5 degreedog,.... s awaawayy frotramm ththee axia&Xiall planeplane.. NormaNormall !aultofaults terminat.terminate ththee foltoldd oonn botbothh ththee eas.utt anandd ththoe wes...... tt (se( •••e figurU gurae J32)2 )..

VeatcV.atchh (1907(1907)) mappemappedd a larglargeo anticlinanticlin.e frotromm ththoe NarrowNarrows nnorthwardorthward..

ThThee writewrit err investigateinveet1gatedd exposureeJCpOlluresa iinn thithias vicinitviCinityy anandd founroundd nnoo evideevidencncee J

811 ofof anan anticlinal.anticlinal .structuretructure.. Eastt dippingdipping .tnt.strata onon thethe wenest limblimb ofof

AAlkalllaHi SSynclinynclinee worewere interpretedinterpreted byby VVeatceatchh ..as alaoalso fforminonningg ththee eeas ..tt limblimb otof ""NarrowNarrows Anticline".Anticline". WestWest otf thiathis esynclina;yncl.1n&ll limb , thethe writer roundfound

WUatchWasatch andand FollkFowke.. s bodobeds inin a noornear horillOnthorizontaall atattitudetitude,, anandd topotopographicallgr aphicallyy

10"lowe'"r thanthan thethe bodabeds ccomprisinomprioingg tthhee oynclinalsynclinal limb.limb. ThiThas evidencavidencee haboos lleedd thethe writerwriter toto thethe concluaionconclusion thatthat &a nonnalnormal faultfault .aseparateparatus ththee !latflat-lyin- lJringg bodobeds frofromm tthhee osynclinaynclinall limblimb..

LandalidLandslide.. s

TwoTwo smallsmall .lslumumpp feature.features wrewere mappedmapped ..as QuQuaternaratert1.aryy landslideslandalldes.* BoBott h fefeatureaturess occuroccur alonalongg thethe tracetrace ofof normanonnall faults.faults. Int.malInternal structures tructuress aarree jumblejumbledd anandd chaotic.chaotic. OnoOne londalidelandslide .....was mappedmapped aboutabout J! milmilee northh of SShelhelll

HollowHollow, aloalonngg thethe SShelholll HoHollolloww FoultFault (Veatch»(Veatch" s ".I.lm;r"Alrny FaultFault"1*)) . The oothethe rr landslidlondalid.e wa_ s mappedmapped aboutabout 1lg, milmile.. s nortnorthh ooff ththoe moutDlOu,thh ooff Whitney CCanyonanyon..

TThhee landslidelandalld•• s areare ootf smallsmall arealareal extent.. Block Blockss ooff WasatcW... tch h anandd FoMkesFowkes strat_trat.a araree involveinvolvedd inin ththee slumslumpp mullSmasses•• . FigurFiguree 12.12. VieVieww eastward,, jusjustt southsouth ooff AlkalAlkalii Syncline,Syncline, showinshowingg localocall anticlinaanticlinall foldfold iinn ththee Wasatcwasatchh anandd BridgeBridgerr (?(1)) formationsformations.. GEOLOGIGEOlOOICC HISTORYHISTORI

GeneraGenerall SStatement atementt

SedimentationSedimentati on,, erosioerosionn anandd diastrophisdiastrophiamm fromm mid-Cretaceoumid-Cretaceouss ttoo latelate

EocenEocenee timtimee areare recorderecorded.d iinn thee exposureexpoaureas iinn tht he areareaa ootf thithiss report..report. LateLate

LaramidI..ram1dee orogenicc activitieactivitiess areare reflectereflected.d iinn ththee area bbyy coarsCo.'reee clutelastii ec depositsdepoai ta,, foldsfold.,, faults,faults, andand depositiodepositi onn ofof extrusivext Naivee igneoui gneous dderivativeserivatives..

TwTwoo thicthickk fonnationsformations ooff limitlimiteedd lateralaterall extentextent,, indicatindicatee localocall d~velopmentdevelopment ootf deedeepp basinb.. 1na s otof depooition.deposition.

CretaceousCretaceous periodperiod

SSandstonesaa:1stones ,J oalcareouacalcareous ssandstonesand. tones ,J andand l.imeetonlimestone.. s aotf thethe upperupper GGannetannettt groupgroup werewere aaccumulatinccumulati.ngg inin thethe areaarea towartowardd thethe ol.oa.close ofof EaEarlrlyy CretaceousCretaceous timet ime.. s.dimentotionSedimentation continuodcontinued v1withouthoutt interruptiinterruptioonn intointo eaearlrlyy LateLate Cre­Cre­ taceoutaoeoWls (CenollWlian)(Cenomanian) time.time. TheThe baoinbasin otof ddepositioepooitionn ousubsideboidedd rapidly,rapidly, fillfill­­ inging with thethe thickthick freshfresh-wate-waterr "halshale•• s am.and limelimestoneltonaes otof thethe BBeaear RiverRiver for­for­ mation.mation. A.Abundanbundantt plantplant roma1naremains andand f'relh-watorfresh-water molluskameliusks inin thethe BeBeaa r R1verElver torm&tionformation suggesuggesstt a moimoistlt, ssub-tropicaub-tropicall climateclimate duringduring CenomanianCenomanian time.time.

FollowingFollowing thothe depositiondeposition otof thethe thickthick BearBear RivRiveerr formation,formation, a lolonngg inintervaterr&!l otof eerosioroeionn or non-deponon-depositioaltionn ensued.ensued. A.A majormajor hiatU8hiatus inin thethe etrastratit i­' grgraphiaphicc sequencesequence coveracove-;* thethe timetime lispapann from.from earlyearly CeCenomanianomaniann toto la.teetlatest

8383 8484

CretaceoWlCretaceous oror eartieetearliest TertiaryTertiary ti.n:e.time. TheThe absenceabsence orof e.u.m.nt.sediments bet_enbetween thethe BBeaq.rr RiverRiver formationformation anandd EvanstonEvanston fOIflllltlonformation isis ooff local.local extentextent,, haw-how­ ever.ever. l&t.Late CretaCretaceouc80ues unconformitieaunconformities araree notenotedd inin surroundingsurrounding areBSareas

(Burger(Burger,, NNixonixon,, Veatch,Veatch, at.et. al..),al.), butbut nonenone oatf asucuchh magnitudmagnitude.,e as thatthat foundfound northnorth ootf ththee towtownn ofof EvanstonEvanston.. DuringDuring ththee periodperiod repraaantcdrepresented 'byby thisthis majomajorr unconformityunconformity,, thickthick,, coanecoarse clutielelastics werlfIII'8e beinbeingg depositeddeposited toto ththoe ....west t ofof thothe areaaro&,, inin ththoe CoalvillCoalville e anandd EchEchoo CanyoCanyonn regionregionos ofof Utah.Utah.

ThThes... e eoueecoarse clutlcielastics wer.... ree derivedderived frofromm highlandhighlandas produceproducedd byby oroerogenigenicc uplifupliftt farthef artherr _et.west.

'Tw'l'woo orogeniorogenicc intervalintervales havhovoe beeboon describedo.cribodd bbyy EardleEa rdloyy (1959(1959)) fromfrom thethe northeasternorth.utemn lJtahUtah regionregion,, covericoverinngg ththee intervaintervall atof UppeUpperr CretCretaceouaceouss timtimee representerepruentedd bbyy ththee Evanston-BeaEvanaton- Bearr RiveRiverr unconformitunconformityy iinn aoutsouthwesterhweatemn doming. According to Eardleyj

**Th"Thee orogenorogenyy indicateindicated.d bbyy ththee basabuall WanW8ll8h1ps hip un­­ conformitconformityy anandd conglomeratconglomeratee i1.0s ColoradColoradoo iinn agagee andand hencehence,, byby definitiondefinition,, i13s pre-Laranddepre-Laramide.. No namnamee hashas beebeenn givegivenn it."it.w

"Th"Th'e EchEchoo CanyoCanyonn conglomeratconglomeratee iiss aapproximatelpproximatelyy equaequall iinn age ttoo ththee conglomeraticonglomeraticc sectio••etio nn ooff thethe PricPricee RiveRivorr formatioformationn ootf centracentrall UtaUtahh (Spieker(Spieker,, 11946)946 ) , althougalthoughh ththee EchEchoo CanyoCanyonn maID&1y havhavee begubogunn ttoo accaccumulatUlllUlatee a littllittlee earlierearlier.. ThThee oroorogengenry hahus beebeenn callecalledd thethe EarlEarlyy LaramidLaromidoe (Eardley(Eardley,, 11951).951 )."»

EardleEardl.y (1959(1959)) furthefurtherr notenot.es thathatt a broabroadd areareaa ooff southwesoouth_tt Wyomin~ngg anandd northeasnorth... tt UtaUtahh wa__s subjecteoubjootodd ttoo foldinfoldingg anandd thrustinthN.ltingg followinfollowingg thothe depositiodopooitionn ootf EchEchoo CanyoCanyonn bedsbode.. ThThoe WillarWillardd anandd AbsarokAilearokaa thrustthruotos araree in-in­ cludeeludedd iinn this. phaseph..... ThThee deformatiode.formationn precedeprecededd depositiodepolitlonn o01f EvanatonEvanston stratastrata,, anandd i18s therefortheretoree ooff MontanMontanaa ageage.. IItt constitutecoll8tltutees ththee majomajorr oroorogengenyy 8585 orof tthhe regionregion,, and Uis olclassifie.... ified d IIIas ththee latlat.e phuephase orof thethe EarlJ"Early Laramid.Laramide

OroOrogengenyy (Eardle(Eardleyy,, 1194194J.,, 11959)959).. UpUplifliltt durinduringg thUthis oroorogengenyy .supplieupplledd thethe claatleaelastics otof thethe EvanstonEvanston formation.formation.

ApproximatelAppro:d.m&tel.yy 14,0014,0000 feet.ett ooff mixemixedd marinemarine,, bbrackish-waterrackiBh-water,, anand.d freshfresh­­ water sedimentl edimentes wer_1"'8e accaccumulatinumulatingg ttoo thethe .uteast inin centralcentral UUintintaa CoWltCountyy,,

^rominWyomingg (Burger(Burger,, 11955)955) , durinduringg ththee ggreatereaterr parpartt ootf LatLatee CretaceouCretacoouos tilllll.time.

Th1aThis sequence.equence,, betweebet..... n ththee bu.base ooff ththee Aspen formationn andand thethe totopp ootf thethe

AdavillAdavillee formationformation,, i11s absenabsentt iinn ththee areareaa northh ooff EvanstonEvanaton.. TheThe EvanstonEvanston formatiofo_tionn i10s absenaboontt iinn centracontrall UinUinttaa County (Burger(Burger,, 11955)955 ), bubutt i10s fofounundd restinreotingg unconformabluncontormablJ"y upouponn thothe AdavillAdavilloe nortnorthh otof KemmererKemmerer,, WyominWyomingg (Trac(Tracyy anandd Oriel,Oriel, 11959)959)..

ThThee FrontieFrontierr formatioformationn i18s exposeexposedd botbothh easeaett anandd wes..att ooff tht hee reportreport areaarea.. IItt iso approximatelapprox1matelJ"y 2,202,2000 feereett thicthickk iinn centracentrall UintUintaa CountyCounty,, WyoWyo­­ minmingg (Burger(Burgor,, 1955)1955 ) , anandd abouaboutt 2,102,1000 feetoott thickk iinn ththoe CoalvillCoalvilloe areareaa otof

UtaUtahh (Madse(Madsonn anandd WilliamsW11l1_,, 1959)1959).. Correlationn oorf otheothorr LatLatee CretaceouoCretaceous formationto_tionas betweebotwoonn centracontrall UintUintaa CountCountyy anandd northwesternorthwootornn UtaUtahh ii8s difticultdifficult duduoe ttoo greatlgreatlJ"y dissimiladiaa1milarr lltho1olithologiesgioa.•

AbsencA.bsencee ooff stratItrataa between ththee BeaSear RiveRiverr anandd EvanstoEVanltonn formationsformationa,, inin ththee areareaa nortnorthh ootf EvanstonEV&nllton,, mamayy bbee explaineexpl&inedd a..s tollow:follows:

aa.* Th'nIel areareaa stoo.tood.d aus a highlanhighlandd durinduringg LatLatee CretaceouCretaceouss timetime,, and

acteacted.d aus a • barriebarrierr betweebetweenn tht hee floof loodd ootf coarscoareee elasticclutlcas ttoo tthhee

wesweatt anandd ththee thicthickk basibasinn sedimentlIIedimentas ttoo ththee .ut.east.

b.. ThThee areareaa mamayy havhavee receivereceivedd thinthin,, shelf-typaheil-typee depositdepoaites durinduringg somlomee

parpartt ootf LatLatee CretaceouCretaceouss timetime.. FollowinFollowingg ththoe depositiondepo8ition,, inin 8686

prepre-Evansto-Evanston formationformation time,time, uplift resultedresulted inin eroeioerosion whicwhichh 1"1-re­

movemovedd thethe a.sedimentciimemtsa downdown toto thethe BBeaearr RiverRiver formatioformationn.. TheThe aarereaa

thethenn ssubsideubsidedd toto formform thethe basinbasin ofof depodepositiositionn ofof thethe Evanston for-for­

mamationticn.

cc.. CombinationCombination ,ofo f thethe aboveabove condiconditiontiona s .!nin whiclilichh thethe areaarea experiencedexperienced intenriliintervals ofof depositiodepositionn andand non-depoaitionnon-deposition ,andan d erOllion.erosion. lntervIntervalw s ofof non-depoeitionnon-deposition or erosionerosion exceededexceeded thatt ofof anyany ddepositioneposition,,

lleavineavingg nono evidenceevidence ofof depositiondeposition having occuoccurredr red .• -

.It..nceAbsence otof anyany furtherfurther evidenceevidence beabearinringg on tthhe histohistorryy ofof thethe UpperUpper

CretaceousCretaceous inin thethe areaarea ofof thisthis report.report preprecludecludees thethe ••selectiolectio n otf anyany oneone ofof thethe aboveabove possiblpossiblee coconceptsncepte.. Therefore,Therefore, thethe UpperUpper CretaceousCretaceous paleo-paleo- gegeologoloDy otf thithiss areaarea IIlWIItmust remain openopen toto ququestioneetlon..

Terti_TertiarI')'y periodperiod

PaleocePaleocennee epoch.epoch. Deposition ofof thethe EvanstoEvanstonn formaformatiotionn bbegaegann i nn lateslatestt

CretaceousCretaceous timetime andand contcontinueinuedd witwithouhoutt interruptioninterruption intointo PaleocenePaleocene time.time.

TheThe basibasinn ofof dopositdepositioion waawas ofof llm1tedlimited areal.areal extentextent andand exceptional.exceptional dopth.depth.

The EvanatonEvanston fformatioormationn hhaus bebeeen mappedmapped ffroromm EvanstonEvanaton,, WyomiWyominngg nnorthwarortlllRlrdd ininttoo tthhee cecentrantrall areaarea ofof FossiFossill BBasinuin,, inin &a narrownarrow beltbelt 4 ttoo 5 milomiles. vide.wide.

SandstonesSandstones andand coconglomeratenglomeratess inin tthhee EvanatonEvanston fonnatioformationn reflectreflect inter-inter­ mimittenttentt phasesphases otof oroorogenygeny.. TheThe clasticselastics bebecomcomee moremore finefine ggrainerainedd toto thethe eut,east, indiindicatincatingg a .atewestermn source.source. CoalCoal andand limestonl.imeIItonee depoaitsdeposits ssuggesuggestt

•a fewfew intervalaintervals ofof quiescencequiescence resultresultiningg inin swampswampyy,, lagoonallagoonal eenvironmentsnvironments..

Followingg EvanatonEvanston depositiondepoeition,, andand priorprior toto ththee floodflood ofof WuatchWasatch elasticaelastics I. 8787

a periodperiod ofof 8rot110nerosion andand non-dnon-depositioepottitionn ensued.ensued. Th1aThis hi.tuahiatus spanaspans latlates.. tt

PaleocePaleocennee andand earlyearl;/ EoceneEocene tilu..time. ErosionErosion cutcut a lsurfacurfacee otof modemoderatratee reliefrelief J,

lIIlichwhich ....was laterlater buriodburied b,.y thothe _"tchWasatch depoaito.deposits. ContinuodContinued upliftuplift toto thothe

vestwest providedprovided a sourcesource torfor ththee thickthick WWasatc... tch h elutica..elastics. Tbi.This lat.late PaleocenePaleocene

upliftuplift 10is callodcalled thothe MiddlMiddlee I.ram1d.Laramid© OrogenyOrogeny (Eardl.,.,(Eardley, 11941941,, 11959)959)..

EoceneEocene EpochEpoch.. FollowingFollowing thethe latelate PaleocenPaleocenee uplifupli!tt toto ththee westwst,, thethe thickk cla8tl0clastic outwa.houtwash atof ththee Wasatcwasatchh formatiofor.mationn spreaspreadd oveoverr a ggreatereater partpart

01of southweslouth.ltt WyominWyomingg anandd northwesnorth... . t Utah. ThroughouThroughoutt IIIOltmost orof thothe raregiongion,, thethe WasatcVa.tcbh wuwas depositeddeposited onon a surfacesurface ofof modermoderatatee relier,relief, uupp ttoo 500500 feetfeet

(Eardley(Eardl.,.,, BurgorBurger,, NixonNiJcDn,, i.e.)i . e.).. RelieReliorf .....was slighlight t inin thethe vicinitvic1n1ty,. northnorth

01of Enn.tonEvanston (maximum(maximum o01f abouaboutt 3030 loot).feet).

fesatchWuatDh depoaltdepositse consisconaiatt primarilprimarilyy ooff conglomerateconglomerate,, coars00arl8e 8ar¥1asandstonestones,,

anandd minominorr amount_untls 01of claystoncla7otonee anandd .iltotono.siltstone. BurgeBurgerr (1955(1955)) conclconcludeudedd thesthellee elasticclutlclIs areare ththee reeultresult oatf torrentiatorrentiall streastreamm actionaction.. TheThe Va..tcbWasatch formatioformationn interfingerinterfingerss wit1d.thh ththee GreeGreenn RiveRiverr formatiof ormationn ttoo ththee easeutt indicatingindicating oscillatinolcillatingg shorelineIhoralinesl anandd changinchangingg raterat.1s o01f sedimentatio.odimentationn (Burger(Burgor,, 11955)955 ) ..

ThThee GreeGreenn RiveRiverr bedbedes araree fresh-watefresh-waterr lake depositdepoelte.s •

BroaBroadd foldinIoldingg followefollowdd ththee depositiodopoaitionn o01f ththee Wasatc__toh h iinn ththoe vic1n1t,.vicinity ooff ththoe Wasatc_atchh Mountain~unta1nos ootf northernorthemn Utautahh (Eardley(Eardl.,.,, 19411941,, 1959)1959).. NNormaol1ll&ll faultinIauJ.tingg accompanieaccompaniodd ththee post-Wasatcpoet-Vaatohh foldingfolding,, anandd probablprobab17y persisteponolotedd untiluntil afteafterr ththee depositiodepositionn ooff ththee FowkeFollke.s formationfomation.. A.itt leastleut,, ththee poetpost-Fowke- lowe.s faultinfaultingg i10s believebelievedd bb7y EardleBaroley,. (1959(1959)) ttoo bbee a continuationn o01f ththoe tauJ.tifaultinngg whicwhichh begabegann durinduringg ththoe post-Wasatcpolt-Woaatchh defdeformationormation.. 8888

VolcanicVolcanic dderivativeerivativ.. s wrewere depoaiteddeposited inin middlemiddle andand lelattee EoceneEocene ttimelJM.. TwTwoo thinthin l'OlIIlWltlremnants ofof a highl¥highly altered.altered ande.iteandesite dopodeposil itt _nowere mamappeppedd inin thothe aarerea northnorth ofof EvanatonEvanston, Wyoming,Wyoming, andand areare tetentativelntativelyy ...assigneigned d toto tthhe Bri3ridd­~ gege r fO",",tionformation ofof middmiddllee EocenEoconoe ((BridgerianBridgerian)) agageo,, on ththee basibuios ofof lltlithologholoSTy andand .tratigstratigraphiraphicc poposition. iHon.. This. woulwo uldd placplec.e thethe firstfirst iigneougnoo""s _NOivoextrusive activitact1vi ty y otof thethe areaarea inin middlmiddlee EocenEocenee time.time.

ThThoe BridgBridgeerr (1)(?) formatiof o"..tionn thickenthicko""s .ueastwartwardd fromfrom approximatelapproximatel¥y 350350 feeteett iinn ththee vicinitvicinityy orof EvanatonEvanston ttoo abouaboutt 1,5001,500 feet ••t nearnear ForFort.t Bridger,Bridger,

WyomingWyoming.. ThiTh10s suggestlugg•• t. s thatthat ththoe centecontor ooff volcanivolcanicc acactivittivityy lalayy ttoo ththee eut.east.

TracTracy anandd OrieOriell (1959(1959)) notenotedd thathatt ststratrataa iinn ththoe centracontrall portioportionn ofof

FossiFooo11l BasinBasin,, tentativeltantativel¥y referredreferred ttoo ththoe BridgeBridgor formatio[o",",tionn bbyy VeatcVeatchh (1(1907)907 ),, forformm aann uppeupperr tongutonguee ootf ththee Wasatcwa.atchh formation,formation, merginmergingg witwithh lowelowrr tonguestongues alonalongg ththoe peripherporiphOl7y ooff FossiFoo.ill BBasinasin..

VolcaniVolcanicc activitactiv1tyy continuecontinuedd intintoo latlatee EocenEooenee timetime,, durinduringg whicvh1chh thethe

FowkeFowke.s formatioformationn iinn southwes.outh ....t Wyomin~mingg and ththoe NorwooNorwoodd formatioformationn anandd ParkPark

City volcanicvolcanic.s iinn northeasIlorthoutt UtaUtahh accumulatedaccumulated..

FossilFo.8118s anandd lithologielithologie.s iinn ththee NorwooNonoodd formatioformationn correlatcorrelatee alolelyclosely witnthh thostho.. e ooff ththoe FowkeFowk.. s formationfo"..tion.. EardleEardloyy (1959(1959)) hahals pointepointedd ououtt ththoe possibilitpossibilityy thathatt ththee NorwooNorwoodd anandd FowkeFowke.s formationformatlonas arar.e ononee and ththee lsameame , botbothh beinbeingg derivativedorivativ.. s ooff ththee Parkk CitCityy volcanicvolcanicss (se(.e.e page 6767))..

ConsiderinConaiderlngg ththee FowkeFowkess anIlldd NorwooNorwoodd formation! o:nnatlonas a..s ononee depositdepollt,, thethe writewriterr believebelieva.s twtwoo possibilitiepoaaibll1tiees exisex1et:t i

11.. The FowkeFollk ••s anardd NorwooNorwoodd pyroclasticpyrocluticas werwree derivede rivedd frofromm ththee ssamamee 889

ssourcourcee asas tthhee: PaParrkk CCitityy volcanics,volcanics, and areare 01of nearnearllyy tthhe lamesame

agoage. Th e tuU.tuffs "",..,were ssubsequentlub. equentlyy ...reworke"" rlcedd b7by flfluviauviall andand la-la­

ccustrinuet rinee pprocessesrocelsea..

2 . TThhee p&Parrkk City volcanivolcanicces andand Fowkea-Fowkes-NorwooNorwoodd formationsformations werewere ddee-­

ririvevedd tromfrom two volcanicvolcanic ccenterentel"'lls dudurinringg latelate EoceEocenne titimeme ..

TheThe mterwriter believes. thethe conditionsconditions outlinedoutlined inin 1.1. areare moatmost accurateaccurate andand coconclusivencluelva. .

EardloEardley (1(1959959) notodnoted thatthat thothe FowkFowke.. s exposureupon.... s otof .osouthwesteruth_tomn lIyomingWyoming areare continedconfined tcto thethe boltsbelts ofof nonnalnormal faultingfaulting whicwhichh followedfollowed tthhoe dero:nnationdeformation otof thethe Wasatcwaaatchh strata.strata. HeHe .statest.t•• st

"Molt"Most otof thethe fault.faults cutcut thethe FowkesFowk .. , butbut ththee ooconn­­ finemefinemennt aotf thethe FowkeFollk.. s volcanivolcanicc outwasQutwuhh toto thethe belbeltt aotf faultfaultiningg indicatindicate.. s thathatt a mainmain drainagodrainage ,..;yway hahadd beeboen ees. ­­ tablistablishehedd beforebefore FonNFowkes depoaition,deposition, andand theretore,therefore, tthahatt deformationdeformation alonalongg the sonezone hadhad occurreoccurredd beforebefore FovkFowke ••s time. TheThe de!'ormatdeformatioiQnn mighmightt welw11l havhavee beebeenn ..associate ,ociatedd witwithh .&Itsalt intrusionintroaion,, solutionsolution,, andand collapa.,collapse, alonalongg witwith faulting.. ItIt ••seem8IU s poaaible,possible, therefore,therefore, thathatt ththee mamajoj orr faultfaultss hadhad boenbeen ..establishetablished d beforbeto,..,e FowkeFowk ..s timetime., anandd thatthat movemenmovementt continued.continued oonn themm afterward.afterward "

FaultsFaults whichwhich cucutt tthhee FowkeFowkess formatioformationn cannocannott bebe accuratelaocuratelyy ddateatedd inin tht he reporreportt areaarea.. ThThe sedimentarled.1mentaryy recorrecordd inin post-Fowkepost-Fowkees timtimee consistconai.etss onlyonly ofof a lolonngg perioperiodd otof erosionerosion anandd recenrecentt depositiodepollitlonn ootf alluviualluviumm anandd ggravelravelas alonalongg streas t reamm valleyv&ll.eyas anandd riveriverr benchesbenchea.. FeFeww ofof ththee faults. araree expresledexpressed iinn ththee presenpreeontt topographytcpography.. StudStudyy of tht heo existin_.tingg faulfaultt linlinee ••escarpment ca rpnent.s gavgavee nnoo indicatioindicationn ooff recenrecentt momovementvement.. GEOJ«>HPGEOMQPPHOUOGHOI.OOY

GGeneraenerall statementstatement

TheThe landland ssurfacurfacee northnorth ofof EvanstonEvanston iais inin thethe latelate yyoutouthh stagestage ofof thethe ggeomorphieomorphicc ccycleycle.. J.A conaideconsiderablr ablee partpart ofof thethe initialinitial erosionalerosional ssurfacurfacee remainaremains undiundissectedasected.. TheThe BSeaearr RiverRiver diapla;yadisplays wellwell developed.developed meandermeanderllls be­be­ tweentween ~Almy andand thethe UpperUpper NNarrowsarrow,, gigivinvingg thethe appearanceappearance ofof maturitmaturityy ..

MeandereMeanders areare notnot chacharacteristir acteristicc ofof thethe riverriver aloalonngg ititas coursecourse aboveabove oorr bbeloeloww thisthis localitlocalityy.. TheThe writerwriter believeabelieves ththee riveriverr baahas reachedreached local,, oror tempotemporaryr ary,, ggradradee inin thisthis vicinity,vicinity, pos.ipossiblblyy duedue ttoo thethe lowlowerin ringg ofof thethe valley throughthrough faultfaultiningg (e(se•• e pagpagee 74).74).

BBroadroad,, pedimentpediment-typ-typee 8I'0810nerosion surfacesudac•• s warewere developeddeveloped oveoverr mosmoett ofof esouthwesouth""ett WyominWyomingg andand adjacentadjacent UUtatahh durinduringg lat.late TertiaryTertiary timetime . RemnanRemnanttss ofof thethes•• e ancientancient erosioerosionn surfaceesurfaces formform prominenprominentt ggeomorphieomorphicc featurere.tureas inin soutsoutherhe mn andand centralcentral UintUintaa CountyCounty ((BurgerBurger,, 11955955;; NixonN1Jwn,, 11955)955),, but areare notnot apparentapparent nortnorthh ofof Evanston.Evanston.

GlaciatioGlaciationn wawass a prominenprominentt factofactorr inn ththee developmendevelopmentt ootf ggeomorphieomorphicc featuresfeatures oonn ththee nortnorthh flanflankk ofof ththee Uinta MountainsMountaina,, 2255 ttoo .3030 milemiless southsouth ofof Evanston.. GlaciaGlaciall featurefeaturess areare founfoundd aaas fafarr nortnorthh ooff ththee UintaUintus ua s

MilliarHilliardd Flanatt (1(100 ttoo 1212 miles southeassoutheutt ooff Evanston)Evanaton),, bubutt araree nonott foundfound iinn ththee areareaa nortnorthh ooff Evanston.Evanston.

90 9191

DrainagoDrainage patte"",patterns

TributariesTributaries otof thethe BearBear RiverRiver northnorth otof ETanatonEvanston tormform a dendriticdendritic drainagedrainage ppatternattern,, andand areare otof thethe conaequentconsequent andand inaequentinsequent varietvarietyy. SuSubb­­ sesequenquentt atstrea ream.m developmentdevelopment 18is ggenerallenerallyy absent.absent.

landformLandt0 "'"s

UptUptilteiltedd .tratastrata aloalonngg tthhe ...eastertern n aid.side ofof thethe BBeaearr Rive r ValleyValley fOnDform

ocuestauest.. s lIhichwhich dipdip toto tthhee auteast andand northeut.northeast. TheThe angleangle ofof dipdip increu8sincreases fromfrom aboutabout tenten degrees &loalonngg thethe auterneastern riverriver valley,.. margimarginn ttoo nnearlearlyy aixt:.sixty degrees. at thethe ...eastertem n extremityextremity ofof thethe mappedmapped area.area.

TlfOTwo land.Udlandslide•• s warewere mappemappedd alalonongg thethe auteast marginmargin ofof tthhee riverriver valley.valley.

BothBoth aarree roundfound inin oloeclose.... associatiooelation n withwith nnormaormal.l faulta.faults. TheThes ••e featuresfeatures

aarree conaidered.considered toto b.be landal1dlandslide• s• fromm tht hee tumbled,tumbled, chaoticchaotic naturnaturee of thethe inCincludel udedd blblockockss otof Wasatch .trat..strata. TheThe cloe8close ...associatiooelation n otof landalllandslidedeas and ffaultaultas suggestsuggeatss a caueecause-and-effec- and.- ef'fectt relationshiprelatlotlllhip,, 1i.e. •••, , landslidelandalldeas rere­­ sultingsulting fromfrom ovorot.openingoversteepening througthroughh faulting.faulting.

TerrTerracacee remnants. werweree founfoundd iinn twtwoo localitielocalitl.. s ,s alonalongg thethe wes".att .ideside

ooff ththee riveriverr valleyvalley,, oppositoppositee AlmyAlrq,, anandd alonalongg ththee .uteast sidaidee ooff ththee riverriver

vallovalley frofromm WhitneWhitneyy CanyoCanyonn nortnorthh approximatelapproximatolyy on.one milmilee (se(.0.e figurefigureos 1313

anandd 14).14). ThThee terracterracee surfacelurtace.s araree presentlpresentlyy abouaboutt 125125 ttoo 150150 feeteett aboveabove

ththee riveriverr bedbed.. TerracTerracee developmendevelopmentt 18is confineconfinedd ttoo outcropoutCl'OJ:as oatf FowkeFollke.s for­for­

mationmation,, althougalthoughh alalll FowkeFowke.s exposureexpoeurees ddoo nonott exhibiexhibitt terracterracee development.development.

TerraceTerraeess iinn ththee AlmA.lm;yy vicinitvicinityy araree clearlclearlyy cucutt oonn totopp ooff a ververyy hardhard,, re-re­

sistan11..atantt limestonlime.tonee bebedd iinn ththee FowkeFolilk.s formationformation.. BotBothh ththee terracterracee IIllrtacesurface

and underlyinunde rlyingg bedbedss iinn ththee FowkeFowkels araree horizontalhorizontal.. RelationRelationas betbetwee.. en n FigurFiguree D . View northeastward from the mouth of Whitney Canyon, showing the structural terrace slong the east side of the Bear River Valley. Figure 14. VieVieww southwestwarsouthwestwardd frofroJlm ththee centracentrall par~artt ooff ththee areaarea,, showinshowingg ththee structurastructurall terraceterracess alonalong:g tht.hee weswestt sidsidee ooff ththee 3ea3~arr RiveRiverr Valley.. 9494

teterracr racee ssurfaceurfacees andand underlyingunderlying FowkesFowkes beds,beds, northnorth ofof WhitneWhitneyy CanyCanyonon,, areare

nnoott cleaclearr .. TheThe terracesterraces araree hhorizontalOrizontal,, butbut thethe undunderlyine rlyingg FFowkee_aas sstratatrata'

areare 10so decodecomposemposed thatthat attituattitudedess couldcould notnot bbee accurateaccuratellyy ddeterminedetermined..

StStrikrikee andand dipdip measurementmeuurementss werweree widelywidely didivergentve rgant,, andand areare consiconsiderederedd unun­­

reliablereliable.. TheThe apparenapparent didipp isis northeastnortheut,, atat a smalemaill anglanglee (fromm twotwo toto

fivf1va e degreedegrees)s)..

TheThe writewriterr believebelieveas thesthesee terraceeterraces araree ofof ththee ststructuraructurall typetype dUedue ' toto

ththee followinfollowingg factors:factors: 1)l) confinemenconfinementt ofof ththee terracterracee developmendevelopment ttoo ex­ex­

posureposuress ofof FowkeFowkees tonnat1on;formation; 2)) limitelimitedd areaareal.l extenextentt ofof ththee terraces;; andand

3)3) lackk ofof terract e rracee developmentdevelopment iinn otheotherr arearea.. s alonalongg thethe river valleyy under­under­

lailainn bbyy sof80ftt strata.strata.

JustJust nortnorthh ooff ththee HewarHewardd RanchRanch,, tht hee BeaBear RiveRiverr abruptlabruptlyy departdeparts. tl'O!llfrom

ititas northerlnortherlyy flofloww alonalongg a grabegrabenn valleyy anarxld turntumas easterlyeaaterly,, cuttincuttingg aa

deedeepp ravin ravinee througthroughh ththee uplifteupliftedd west flanflankk ooff ththee AlkalAlkalii SynclineSyncline.. The

riveriverr emergeemergess frofromm thithiss ravinravinee flowinflowingg westwest,, continuincontinuingg intintoo UtahUtah.. TheThe

arcuatarcuatee ravinravinee iss termetennedd ththee "Narrows''Narrow''" (seee plat platee 2).2).

FowkeFowkees stratstrataa occupoccupyy ththee northernorthernn extremityy ooff ththee grabegrabenn vallevalleyy jjusustt nortnorthh ooff ththee poinpointt wherwheree ththee riveriverr turnturnss easeastt anandd enterentems ththee UppeUpperr NNarrowsarrow..

ThThee riveriverr crosseCros ...s a majomajorr normanormall faulfaultt botbothh upouponn enterinenteringg anandd emergineme rgingg frofromm ththee NarrowsNa r row,, anandd i1ss discordandiscordantt witwithh structurestructuress iinn thithiss localitlocalityy ..

ThThe developmendevelopmentt ooff tht hee BeaBearr RiveP~ver courscoureee througthroughh ththee NarrowNarrows mamayy bbe

aa resulresultt ooff superpositiol uparpoe1tionn afteatterr extensivextenaivee FowkeFowkess floodingflooding,, oorr antecedeantecedenntt streastreamm developmendevelopmentt durinduringg anandd afterr faultingf aulting,, oorr a combinatiocombinationn ooff bothboth.. TheThe writerr iiss unablunablee ttoo makmakee a definitdefinitee conclusionn regardinrega~ngg ththee above.above. ECONOMIECONOMICC GEOLOGGEOlDGYY

GeneraGenerall statestatemenmentt

ConsiderablConsider ablee bituminoubltwninouas coacoall wawaas producedd frofromm ththee EvanstoEvanatonn formationformation neanearr AlmAlmyy frof romm 18501850 ttoo ththee earlearlyy parpartt ooff ththee 20t20thh CenturyCentury.. CoaCoall miningraining iinn thithiss arearea hahaas nonoww entirelsntirelyy ceueceasedd ..

OilOil occurrenceOCCurrencess inin Uinta County werweree firsfirstt reportereportedd bbyy Claytonn (1(1848848,, p.. 118-24)8-24).. ExploratioExplorationn forr oiloil hahaes beebeenn sporadioporadicc sincoinceo thathatt timtimee anandd pproro­­ duductioctionn haahas occurreoccurredd iinn .everalseveral instancea,instances, althougalthoughh iitt habaas beebeenn ooff minorminor econoeconomimicc impoimportancertance..

HighwayHighway coconstructionstructionn materialmaterialas and ceramiceramicc clayclay ddepositepositas areare minedmined inin tthhee vicinitvicinityy ofof EvanstonEvarwton,, butbut areare ofof minminoorr aceeconominemec importanceimportance..

CoalCoal

LowLow ggradradee bibituminoutuminouss ccoaloalas occur inin tht he EvanstoEvanaton formationn inin tthhee vicinityvicinity ofof AAlmy~ . SeveralSeveral minmine ••s werweree opeopenenedd inin thit hiss areaarea duridurinngg ththee lattelatterr partpart ofof thethe 19th CeCenturyntury. TheThe towntown ofof AlmyAlmy wawass establishedestablished aaas &a resultresult ofof thethe coalcoal mining actiactivityvit y,, butbut hhaaas aisincncee bbeeeen abanabandonedonedd vitwith the exceexceptioptionn of a fewll' ranchuranches andand rams.farms• Un.!Unfavorabla·{orablee economiceconomic conditioconditionsna,, togtogetheetherr withwith fifireress 1in tthhee minmineses, broughtbrought aboutabout tthhee closclosiningg ofof miningmining opeoperationr ationss manymany yeyeara'"s ago . VoVeatcatchh (1(1907907,, p . 113-13113-1399) ggiveive.s a thoroughthorough Osummarlllml&l')'y ofof tthhe AlmyAlmy coalcoal indindustryustry.. 9595 9696

CoalCoal productionproduction throughoutthroughout odjacentadjacent pcrt.ionaportions otof UintaUinta CountTCounty baahas bbeeeenn moremore conelotootconsistent andand profitableprofitable thanthan inin thothe EvanetonEvanston areaarea.. Impcrt.antImportant pproro­­ ducingducing horizonhorisonas throughoutthroughout thethe county areare thethe Frontier,Frontier, Adaville, .. Evanaton,Evanston, aniand BeBeaa r RiverRiver lo:nnationa.formations. TheThe FrontierFrontier formationformation huhas beenbeen thethe mosmoatt im­im­ portanportantt coalcoal prod\lcer.producer.

011Oil

Oi011l apringe,springs, or seepsesepa,, werwree presumablpreaumablyy knownknown ttoo .manymany earlyearly ••settlerttlll1J s ooff .outsouthwesh.... t WyomingWyoming.. ClqtonClayton (1848(1.848)) ....was firotfirst toto recordrecord thest he ••e occurrencoccurrences... .

SporadiS,poradicc drillingdrilling ootf ththee areaarea followedfollowed,, witnthh unsuccessfuUJl8ucc ••st'ul l reeultaresults ,J untiluntil ththee Tearyear 1900.1900. IInn thathatt yeaTearr ththee UnioUnionn PacifiPacificc RailroodRailroad encounteredencountered 011oil inin a testeat hole.hole. ThThereree follfolloweowed.d a short-lived,short-lived, butbut int.neeintense perioperiod.d otof 011oil exex­­ ploration..

NNoo commerciacom e rei&!l productioproductionn ootf oi011l hah&as beebeenn reportereportedd iinn southweslouthW88tt Wyoming,Wyoming, althougalthoughh numerounumoroWls well...llo s havhavee beeboenn drilledrilledd uupp ttoo ththee timtimee ooff thith10s writingwriting

(1961)(1961) .•

PossiblPOlliblee oi011l structurestructurels araree ththee StovStovee CreeCreekk structurstructuree neanearr Hilliard,Milliard, anandd ththee SulphuSu~phurr Creekk fielfieldd southwes.outh_tt ooff EvanstoEvan.tonn (Nixon(NiJoon,, 1955)1955).. AspenAspen anandd SeaBearr RiveRiverr shale.hal•• s appear ttoo bbee ththee sourcsourcee bedbedes fotorr ththee oi011l iinn thithiss re­re­ giogionn (Eardley(EardleT,, 19591959;; BurgerBurger,, 19551955;; VeatchVeatch,, 19071907;; etet.. al.).al.).

OiOUl exploratioexplorationn iinn UintUintaa CountCountTy ii.s madmodee difficuldifficultt duduoe ttoo tht hoe maakingmasking ootf underlyinunderlyingg geologigeologicc structureatructurees bbyy thicthickk WasatcWBaatcbh beds. 9797

IIighwayHighway materimaterialalJls

CoConglomeratenglomeratesl inin thethe BBrown'row'ss PaParirk: andand W'Wasatcuat ch formationtormationas araree uutilizetilisedd

.aass fofoundatioundationn matemateriariall inin the construction ofof highwayshighwa3B.. GGraveravell pitpitss areare situates ituat edd jusjustt euteast of EvEvanstonanston..

Cera:nicCeramic claysclays

ClaCla,yy miningmining operationsoperations inin ChristenseChristel'lsenn HollowHol low, abouaboutt oonnee milmil e easeastt ofof thethe reportreport areaa rea,, werlo'Sree inin thethe initiainitiall stagestag_s duringduring tnt hee summe8 Ul1illlE1rr of 1I960960..

PrivatPrivatee individualindiv1duw s ar a ree conductinconductingg thithiss enterpriseant.rpme,, and ththee writewriterr was unun­­ ababllee ttoo learlearnn mucmuchh abouaboutt ththee naturnaturee ooff ththee depositdepoeit.. TheThe materiamateriall iiss lilighghtt gragrqy toto ...miwhitet e,, ana.ndd iiss exposeexposedd iinn tht hee canyocanyonn floor.. TheThe writewriterr bbelieveelievess thee materiamateriall comecomess fromm ththse FowkeFowkes formationforoatlon,, duduee ttoo iti tss colocolorr anandd ooccurccur­­ rencerence.. ClaClayy i13s shippeahiwedd bbyy tructruckk frof romm Evanstonn ttoo Salsalt LakLakee CityCity,, UUtahtah,, wherwheree iitt i1.s utilizeutilisedd iinn ththee manufacturmanufacturee ooff whit~t.e buildinbuildingg brbrickick..

ExposureExposuress ooff FowkeFowkes strat:strataa oonn tht hee nortnorthh sidaidee of Whitne\'hitneyy CanyoCanyonn cocontaintainn a highighh percentagpercent&{;ee ooff clayclasrstone,s tone, whiwhicch appearappearss ttoo bbee quitquitee bentoiiitiebentoni t ic.. Min­­ ini ngg of thiss materiamate riall coulcouldd be accomplisheaccomplishedd bbyy strippinotrippingg methodsmethode,, anandd ccoulouldd provprovee ttoo bbee economicalleconomicallyy profitableprofitable. BIBUOGRAPHYBIBLIOGRAPHY

Andrewe,Andrews, D.D. A.A. (1944),(1944), PreliminaryPreliminary GeologicGeologic £!S!and stStructur ructuree MapMap ~and ..92!!Coal Sections,Sections, WillowWillow ~Creek CoalCoal Are",Area, LincolnLincoln County,County, Wyoming.Wyoming. UU.. s.S. GeologicalGeological SUF~ey.Survey.

Atwood,At wood, WW.. WW.. (1909)(1909),, GlaciatioGlaciationn ooff th!ill!!e UintUintaa anandd Wasatcwasatchh Mountains.Mountains. u.U. s.S. GeologicalGeological SurveySurvey Prof.Prof. PaperPaper 6161./

Barrett,Barrett, Da.vidDavid W.W. (1953),(1953), MicropaleontologlMicropaleontology ~of !:h!the EvanstonEvanston formation,formation, southwesternSouthwestern WYOllling.Wyoming. M.M. 8.S. Thesis,Thesis, UniversityUniversity ofof Utah.Utah.

BarBartram,t ram, J.J. C.C. (1937),(1937), UppeUPEerr CretaceousCretaceous 2!of ththee RockyRocky MountaiMountainn AreaArea.. AmAm.. AssocAssoc.. PetroleumPetroleum GeologistsGeologists BullBull.. 21,21, pp.pp. 899-913,899-913, anandd 1592-1594.1592-1594*

BradleyBradley,, WW.. HH.. (1936),(1936), GeolIlorpholof!.YGeomorphology ofof 2th e Nort~h FlanFlankk ofof !:h!the UintaUinta Ivlounta;IlS.Mountains. UU.. 8.S. GeologicalGeological SurveySurvey ProfProf.. PapePaperr 185185..

Burger,Burger, .;.J. A.A. (1955),(1955), GeologGeolog;'(y .2!of CentralCentral UintaUinta County,County, WYoming.Wyoming. MM.. S.S. ThesisThesis,, UniversitUniversityy ofof Utahutah.. "~ ""

Clayton"Clayton, W.W. (1848)(1848),, !h.!The Latter-DaLatter-Dayy Saint!Saints Emigrants'Emigrants* Guide.Guide. st.St. Louis,Louis, 1'40.Mo.

CobbanCobban,, WW.. A.A.,, anandd ReesideResaide,, JJ.. B.B.,, JrJr.. (1951)(1951),, OccurencOccurencee !2.!of LowerLower Q!:!::Cre­ taceoutacaouss AmmoniteAmmonitess i!!in ColoradoColorado,. WyomingWYoming,, ~and MontanaI.fontana.. AmAm.. Assoc.Assoc PetroleuPetroleumm GeologistGeologistss Bull.Bull.,, volvol.. 3535,, nono.. 8,8, pppp.. 1892-1894.1892-1894.

(1952),(1952), CorrelatioCornl&tionn S1!of ~the CretaceouCretaceouss formationfO!fI!ltionss .2lof ththee Jrl!BternWestern InterioInteriorr ~of !h!the UniteUnitedd Statesstites.. GeolGeol.. Soc.Soc AmAm.. Bull.Bull.,, volvol.. 636),, pp.pp. 1011-1044.1011-1044.

(1952)(1952),, FrontieFrontierr formationformation,, Wyoming, .!ill!and AdjacenAdjacentt AreasAreas.. AmAm.. AssocAssoc.. PetroleuPetroleumm GeologistGeologistss Bull.Bull.,, volvol.. 3636,, nono.. 1010,, pppp.. 1913-1961.1913-1961.

CoodyCoody,, GilberGilbertt LL.. (1957)(1957),, GeologGeolog.Yy ooff ~the DursDutl!tt Mountain-HuntsvillMountain-Huntsvillee Are".Area. MorgaMorgtpn !!!fiand Webe~r CountiesCounties,~., Utah. MM.. SS.. ThesisThesis,, UniversitUnivensityy ooff utah.Utah.

CopeCope,, EE.. DD.. (1874)(1874),, UU.. Ss.. GeolGeol.. anandd GeogrGeogr.. SurveSurveyy ooff ththee TerritoryTerritory,, 7th7th AnnuaAnnuall ReportReport,, pppp.. 435-444.435-444*

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Ea"u8Eardley",, A.A. J. (1944),(1944), GoologYGeology 2!of thethe NNorth-Centraorth-Central.l 'MutchWagatch It>unItoitainsttina., ~.Utah. Gool.Geol. Soc.Soc Am.Am. Bull.,Bull., vol.vol. 55,55, pp.pp. 8819-89419-894.*

(19(1951)51),, StNctUrtJ.Structural CeologYGeology 2!of NNortorthh America.America. lI&~rHarper BBrothersrothere,, NNeeww YorkYork..

___ (1(1952)952),, WasatchWasatch Hinterland.Hinterland. utahUtah Gool.Geol. Soo.Soc,, GuidebookGuidebook nnoo.. 8,8, pp.pp. 5252-60- 60..

(1(1959)959),, ReviRevie.ww ofof GeologyGeologj ofof NNortheasterorth... tem n utahUtah endand SOSouthwesteruth.... tem n ~Wyomingming .. GGuideboouidebooktok to thethe GeOloGeolog!!7y ofof thethe ....Wasatc&tOli h endand uilit&Uinta MtHbnsna.. Transitioran.it1on Are.,Area, IntennountainIntermountain Aaloe.Assoc. PetrolePetroleuumm o.oGeologistlogilt.s TenthTenth AnnualAnnual FieFielld GontereConferencenco..

Egbert, RoRoberbertt L.L. (19(1954)54) , GoologyofGeology of thothe ~East Cl!1l'OCanyon AreArea ••, It>rsMorgaann Gounty,County, J1a!!.Utah. M.. S.S. ThoThesis.i., UnivUniversitoroity" ofof UUtahtah..

Ermnona,Emmons, S. F.F. (1(1907)907) , Uint.a It>unt^fountainsaina.. Ceol.Geol. Soc.Soc. AmAm.. BullBull..,, vol.vol. 18,18, . no.no. 1,1, pp . 287287-302-302.,

Englemann, Henry (1858), Preliminary Report on the Geology of the Country Eng).omann,bbetweeetJl!!n nH onry ForFortt (BridgBridge1858) e~, r ~~~:P~~~~~~~m;~_ and Camp Floyd, Utah Territory .II!!an dof ,o southwesthouth !!Hteountcrt ofof ~the Latter PlacePlace ~Along Capjb. J. H. Simpson?s Routes. SSenatenatee Ex.Ex. Doc.Doc. no . 40,40, 35t35thh GongreCongress .. , 2nd Session, 1859, pppp.. 45-75*

FremontFremont,, JJohohnn C.C. ((1845)1845),, ReporIltportt ofof ExploratorExplorato!7y Expeditionn 12to ~the Roc1<;yRocky Mountain~unt oinos ~and toto OregoOregonn .II!!and !:2to NortherNort.hemn Californiac"J.1!orni... HousHouo e ExEx.. DDooc.c no . 110606, 28th28th CongressGongre•• , 2nd2nd SessionSo ••i on,, 1845,1845, pp.. 131131.*

C-augerGauger,, D.JD. J.. (1952)(19.52 ) , M1crottunlMJcrofauna ootf ththee HilliarHilliardd formatiofOrmationn nearnear EVan,toEvanstonn,, ltiomiry

GazinGamin, CC., L.L. (l(1942)942 ),, FossiFOOli1l !1tMammalimmlJlaa fromm ~the Alm~y formatiofo!llltttionn in Western WyomingWyoming . JJourour. WashingtoWuhingtonn .lead.Acad. Science,, volvol.. 32,32, pppp.. 217-220.

^ (l(1952)952) , !!!!The lo"'rLower EoceneEocene KnighKnightt fo!llltttionformation 2!of WesterW.. tem n !Qyming,Wyoming, £l!!and .ll!its MammaliaMann.11ann F,1lPH.Faunas. SmithsonianSmithsonian MiscKiac. CollectionsCoUect1oM,, volvol.. 117117,, no.no. 18lS.

(1956a)(l956&),, ThThee OccurrencOccurrencee ooff PaleocenPaloocanoe Mammalia_Henn RemainRamainas iinn ththoe Fossil --"'BasiB"'uinn ~of SouthwesterSoutiiW.temn WyomingW;romiiii.. JourJour.. PaleontologyPaleontology,, volvol.. 30, pppp.. 707- 771111.*

__.,.,- (1956b)(1956b), ThThoe UppeUpperr PaleocenPaleocenee Mammali"....,.11&a ~from ththee Alm~y formationfO!l!!&tion,, inin WesterWe.temn WyomingWYom1.n8 . SmithsoniaSmithsoniann MiscMisc.. Collections,, volvol.. 131131,, nono.. 7.7. 100100

Guin,Gazin, C.C. L.L. (19(1959)59 ),, FaleontologicaPAleontologicall 1W?lorationExploration andand Dati""Dating s!.lliof the EarlyEarly TorU,'ZTertiary DoDepositmitas .!!!in BasinBMinos AdjacentAdjacent ~to llithe Uinta M>untaino.Mountains. GGuideuide­­ bookbook ttoo ththoe GoologyGeology otof ththoe WlaatchWasatch andand Uinta M>untainoMountains TranaitionTransition Area,Area, IntennountainInte mountain A..oc.Assoc. PetroleuPetroleumm GeologutaGeologists TenthTenth AnnualAnnual FieFiell dd Conference.Conference.

Hall,Kali, JameJams os (1845),(1845), ReporReportt 21.of thethe Explorato'ZExploratory ExpeditioI!Jq!odUionn ~to ththoe IlocgRocky Mountainstbuntaine , m.,etc., £zby. Fremont.Fremont. IInn HouseHouse DDococ.. no.no. 166,166, 28th28th CongreCongressss,, 2nd2nd SeSession ..ion, , pp. 304304-307- 307,, andand 309.309. lla,yden,Hayden, F. V?.. (1869),(1869), PreliminarP!,!l,1ndl1&'Zy FielFioldd Report.. UU.. S.S. GeologicalGeological SUrveySurvey ofof ColoColo., anandd NeNow !lex.,24ex., 3r3rdd AnnuaAnnnall Report,Report, pppp.. 9900,, 92, andand 98..

__-,; (1(1871)871),, FourtFourthh AnnUAlAnnual Prel1mina'ZPreliminary ReportReport.. UU.. S.S. GeologicaGeologicall Survo,.Survey ofof W;yom1ngWyoming andand portiol18portions ooff ContiguousContiguous Territory,Territory, pp.. 49.49*

__= (1(1874)874) , U. S.S. GeolGool.. anandd Geogr.Geogr. Survey ofof ththoe TerritoryTerritory,, BullBull.. 1,1, nono.. 22,, pppp.. 1 anandd 2.2.

Imla;y,Imlay, RalpRolphh WW.. (1950)(1950),, JurassiJureoicc RockRockss inin ththoe !!ounta1ll!Mountains Alon!.J.o1lJ!g ththoe }l!llWest ~Side 21.of thee GreeGreenn RiveRiTerr BasinB.. in .. WyomingWyoming GeolGeol.. Assn.A.. n. ,, 5t5thh AnnuaAnnnall FieldField CoConferencnferoncee GuidebookGuidobook,, pppp.. 37-49.37-49.

__-,,;- (1952)(1952 ),, CorrelatioCorrelationn ootf ththee JurassiJUraeoioc FormationFOP]lftioll!s ootf NortNorthh ""'rica,America* ExclusivExclusivee ofof CanadaCtnt4a.. GeolGool.. SocSoc.. AmAm.. Bull.Bull.,, volvol.. 6363,, pppp.. 952952-953- 953,, SeptemberSept_or.. .

JonesJono.,, DD.. J.J.,, PicardFicard,, I!.M. DaneDane,, anandd ifyethWyeth,, JohJohnn CC. (1954)(1954),, CorrelatioCorrelationn otof Non-MarinNon-Marinee CenozoiCenosoice oot~.f Utah. AmAm.. Assochloc.. PetroleuPetroleumm GeologistGeologistss BBull.ull.,, vol.vol. 3838, no.. 1100,, pppp.. 2219-22222219- 2222,, OCtober.October.

KingKing,, ClarencClarencee (1876)(1876),, PaleozoiPaleolOicc SubdivisionSubdivio1op.os J!!!on llithe 40t40thh ParallelPArallel.. AmAm.. JourJour.. ScieneeSCience,, 3r3vdd seriesaeriel,, volvol.. 1111,, pppp.. 475-482.475-482.

KnightKnight,, WW.. CC.. (1902)(1902 ),, PetroleuPetroloumm FieldFieldos gfof framing!troming,. illlIII; ththee FieldFieldos ofof UintUintaa CountyCounty.. EngineerinEngineeringg anandd MininI!1ningg Jour.Jour.,, volvol.. 7*373,, pppp.. 720720-722-722..

___ .,- (1903)(1903),, Q2.IlCoal FieldFio]40s o21.f SoutherSouthemn UintUintaa CountyCounty,, Wyomingltroming.. GeolGeol.. Soc.Soc. AmAm.. Bull.Dull.,, volvol.. 1313,, pp.. 543.543.

Lankfordlankford,, RR.. R. (1951)(1951),, MJcropaleontoiogIIicronaleontologyy gfof !:!l!the WanahiW&nah1pp AreaArea.. MII. S.S. ThesisThe.i. ,, UniversitUniven1tyy ooff utah.Utah.

LarawayLaraws;y,, WilliaWi1110mm H. (1958)(1958),, GeologGeologyj ooff th!:!l!e Southh l.2r!!Fork o21.f !:!l!the OgdeQ&denn l!U!!:River AreaArea.. M.. S8.. ThesisThesis,, UniversitUn1vel'llityy ooff Utah.Utah. 101101

1&La Rocque,Rocque, AA.. (1(i960)960 ),, IIolluac!l!lMolluscan F,U!ltOFaunas !l!!!!!of the flwtr,!fFlagstaff fonnationformation ofof CentrtJ.~.Central Utah* Geol.Geol. 500.Soc. Am.Am. I!elllOirMemoir 78.78.

LeoquoreuxLesquereux, LeoLeo ((1872)1872) , LigniticLjgnitic FFormationOl'lll&tioll!s I!lSand fce.illl.2!:a.Fossil Flora, u. S.S. GeologicalGeological SSurveurveyy 6th6th AnnuaAnnuall ReportReport ofof thethe Territory,Territory, pppp.. 317-426.317-426. lovo,Love, J.J. DD..,, WaitsWeit.,, J .. L.L.,, on

Madson,Madsen, J .. H.. JrJr.. (1(1959)959) , GeologyGeology ofof thothe ~Lost Creek-EchCreok-Echoo Cl!lY!!Canyon Area.Area. M.. s.$• ThThesis •• i.,, UnivUniversiteroity ooff UUtahtah..

Manatleld,Mansfield, G. R. (1927),(1927). GeographY,Geography, GeologY,Geology, ~and MinMineraerLll Re'ource.Resources ofof ~Part ofof SguthoMtemSoutheastern IdahoIdaho.. U.U. S.$. GeologicalGeological SSurveurv. y ProfPref.. PaperPaper 152.

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Martinl'.artin,, BrucBrucee DD.. (1954)(1954),, II1Mlcropaleontologcrepaloontologyy ofof ~the AdavillAdavillee fOl'lll&tion.formation. MK.. S.S. ThesisTho.lo,, UniversitUnivoroityofy of UtUtahah.. lIook,Meek, F. BB.. (1873)(1873),, SixtSixthh Annual Report. U. S.S. Geol.Geol. anandd GeogrGeogr.. SSurveurveyy ofof ththee TerritorTerritoryy foforr 1872, 1873, pppp.. 451-452451-452,, 462.462.

MountMount,, DD.. LL.. (1952)(1952 ),, GeologGoology!l!y of thi!!!e Wanahip-ParIBnahip=Parlck CitCityy RegionRegion,, UUtahtah.. MH.. S.S. ThesisTheaia,, UniversitUn1v8I'8i.tyofy of Utah.Utah.

NixonN1=,, R. PP.. (1955)(1955),, GeologGeology!l!y of ~the HilliarHilliardd !l!!miryI.. M.. SS.« ThesisTho.i.,, UniUniversitveroity ooff UtahUtah..

PealePeal.,, AA.. CC.. (1877)(1877),, EleventEl.vonthh AnnuaAnnuall ReportRe~rt.. GeolGeol.. anandd GeogrGoogr. Survey ofof ththee TerritorTorritoryy foforr 1877,1877, 18791879,, pp.. 53536 •.

PetersonPeteroon,, RR.. H. (1950)(1950),, MJcrofossilHicrefoooills ~and CorrelatioComlltionn ooff £A ParPartt o2!f ~the FrontieFrontierr formationfonnatlon,, CoalvilleCoalville,~., Utah. Mli.. SS.. ThesisTheau,, UniversitUn1ve reityy ofof Utah..

PetersonPet.~on,, R.. H.H.,, GangerGauger,, DD.. J.J.,, anandd LankfordLa.nkford,, R. E.R", EditeEditedd bbyy DD.. J.. JJoneoness (1953)(1953 ),, MJcrofossilMicrofo!8ilfs ooff !!!!the UppeUPJl!rr CretaceouCret,,,o\lfs o2!f NortheasterNorth,ytomn ~Utah ~and SouthwesterSout.lJ.l!e!temn Wyomingl(yomiryI. UtaUtahh Statstatee GeologicaGeologicall anon

PowellPowll,, JJ.. WW.. (1876)(1876),, ReporReP5!rtt o2!!n thetoe GeologGeologyy ooff ththee EasterEutomn PortioPortionn ooff ~the. Uintaa Mountainslbuntr,1r.... UU. 3S.. GeolGeol.. anandd GeogrGoogr.. SurveSurvoyy ooff ththee Territory,Territory, 2n2ndd Div.Div.,, pp.. 115656.. 101022

Randall,Randall, A.A. GG.. (1952),(1952), AAreareal.l GeologYGeology g!of 1!l!the PinecWtPinecliff AreaArea. SummitSummit CountCountyy,, !!EiIl.Utah. IIM.. 8.S. Thelia,Thesis, UniveUniversitnity otof UtUtaholl..

Raeeide,Reeside. J. B3.. Jr.,Jr., ondand WeWeymouthymouth,, A.. A.A. (1931),(1931), IIoUuekoMollusks f!2!!!from 1!l!the AepoAspenn shaleshale (C(Cretaceousretac:'OHI)) otof Southp.temSouthwestern Wxom:inB;.Wyoming. Proc.Proc U.. S.S. NNatlatl.. Muaeum,Museum, vol.vol. 7788,, AArtrt.. 1177,, pp.pp. 1-24.1-24.

RichRichardsards,, R.R. W. ,, andand lIanetield,Mansfield, G.. R.. (1912),(1912), ThoThe BtIlIlBannocock Ovorthruot,Overthrust. .!a. MMajoaJor Fl!lltFault !!!in S9Southeasterutho~tomn ldo)loIdaho !!11dand NNortheastero rthoutem~.n Utah. Jour.Jour. GeologyGeology vovoll . 20,20, pp.pp. 681-7071-707..

Richardson,Richardson, G.. B.. (1(1941)941) ,, GeoGeologlogy!!!!!y and MinoralMineral RaoourcooResources g!of thethe RandolphRandolph Quadrangle,Quadrangle. utUtah-Wyomingr.l!-!tY!)ming.. U.. S.S. GeologicGeologicaal.l SurvoSurvey BBullull.. 923.923.

Rubey,Rubey, W.W. w.W. (1(1958)958) , GeGeologologyy of 1!l!the BodfBedforordd QuJd!"ll!ll!10,Quadrangle, Wzoming.Wyoming. U.. SS.. GeologiGeologicacal.l SurveySurvey QuadrangleQuadrangle MapMap GO-109GO-109..

Rubey,Rubey, W.W. W.,W., anondd Hubbort,Hubbert, IIM.. K.K. (19(1959)59),, Ovorth"",tOverthrust BBeloltt iinn GeoGeosynclinasynclinal.l !IUArea ooff W"teWestermn WnmingWyoming !!!in .I.!.g!rt.light otof FluiFluidd ProPressurosuree ItYpothuypothesis ..lo. . GeGeolol.. Soc.Soc Am.. Bull.Bull.,, vol.vol. 70,70, pppp~. 167-206-206..

SSchickchick,, R.. B.. (1955(1955)) , GeologyGeology ofof ~the IIorlllnMorgan-Henefe- l!oneforr AreaAre.,,~. Utah. M.. SS.. Th.eie,Thesis, UniUniversitvonity ooff UtUtaholl..

__~ (1959)(1959),, GeologiGeolodcc SectionS,ction.s !:l:!!!!from Th!'!eThree DeepDoep. WellsWells,, SoSouthwesteruthwe. tomn domingWxom:inB;.. GuidebooGuidobookk ttoo ththoe GeologGeologyy ooff thothe Wasatc_ atchh andand Uinta Mountainunta1nss TTransitioranaitionn AreaArea,, IntemountaiInt.mountainn AssocAsaoe.. PetroleuPetroleumm GeologiatsGeologists TentTenth AnnuaAnnuall FielFieldd Conference.Conference.

SchultzSchult.,, AA.. R. (1914)(1914), GeologGeol ogY!!!!!y and GeographGeOgraphyy g!of .!a Portionn g!of Lincollincolnn CountCountyy , WyomingWnming.. U. SS.. GeologicaGeol ogical.l SurveSurveyy Bull.. 543543.^ "

SearsSears,, J.. D.D.,, anandd BradleyBradley,, W.. HH.. (1924)(1924), RelationRelationes ooff ththoe Wasatc_atchh anandd GreenGreen RiveRiverr formationfO!lllltionos iinn NorthwesterNorth_temn ColoradColorMioo !!!!!and SoutherSouthomn WyomingWxoming,, l!ll!!with Notelloto.s o2!!n OiOil^ ShalShaloe !!!in ththee ll!:!.!!!Green RiveRiV\lrr formationt ormation.. U. SS.. GeoGeologicalogiCal.l SurveSurveyy ProfProf.. PapePaperr 115656 ..

Stantonstanton,, TT.. WW.. (1892)(1892),, ThThoe StratigraphiStratig!'l!phicc PositioPositionn of ththoe BeaBu r RiveRiverr tor­for­ mationgt1on.. AmAm.. JourJour.. ScienceScienc.,, 3rJrdd seriessarl.es,, vol'YOl .. 143143,, pp.. 9S98-115- 115.. __ =_. (1B93)(1893),, !l!!The ColoradColoradoo formatiofonnationn £!!!and ititos InvertebratInvertebratae FaunaFI1l!!t.. UU.S. S.. GeologicaGeologicall SurveSurveyy BullBull.. 106, pppp.. 3737-38- 38..

__= (1897)(1897),, StratigraphStratigraphyy !!!!!and PaleontologPaJ,eontolpgyy g!of ththoe LaramiLaramioe !!ll!and IlAIlatodRelated formationfOrp1ftionss iinn WyomingliYomins . GeolGeel.. SocSoc.. AmAm. Bull.Bull.,, volvol.. 88. 103103

StoStokeske.,, MaJoin.. LL.. (1959)(1959),, JurassiJurua10c RockRookss 2!of .:!!!the Wasatc_atohh RangRangee .!!!!and ViVicinityoinit Z., GuidebookGuidebook ttoo ththee GeologyGeology ooff thethe WasatcW.. atoh h andand UinUinttaa MountainsMountains Tran­Tran­ sitionsition AreaAre.,, IIntermountaintennountainn Assocbloc.. PetroleuPetroleumm GeologiatsGeologists TentTenthh AnnualAnnual FielFieldd Conference.Conference.

TracyTraoy, J.. II.. JrJr..,, anandd Oriel,, S.S. SS.. (1(1959)959),, UppermosU!J!!!!nnostt CretaooousCretaceous anandd Lowerr TertiarTe rtia ryy RockRookss ofof thethe FossiF",oill BBasinasin.. Guid.bookGuidebook toto thethe GeoloGeologgyy ofof thethe Wasatc'Wasatch andand Uinta l-bMountainunta1.nss TransitTransitioionn Area,Area, IntermountaiI ntermountainn Asaoc.Assoc PetroleuPetroleumm GeologistGeologiatas TTententhh AnnuaAnnuall FieldField Conference.Conference.

VeVeatchatch,, AA.. CC.. (1907)(190'7),, GeographyGeography ean d GeologyGeology ooff •a . PortioPortipnn ooff WesterWe.temn m­do­ l!!!!!g..ming. uU.. S.S. GeologicaGeologioall SurreSUM'O;Yy Prof.Prof. Paper 56.56.

WegemannWegemann,, C.C H.. (1915)(1915),, ThThoe Coalvill.Coalville £!!Al.Coal FieFieldsl d ••. U.. SS.. GeologioalGeological Sur­Sur­ vey Bull. 585811,, pp.. 1161-18461-184..

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WilliamsWilli_,, H.H.,, TurnerTumer,, F.. JJ.. ,, anandd GilbertGilbert,, C.. iIM.. (1(1955)955) , PetroPetrographygraphy.. Ww.. H.. FreemaFreemann anandd Co.,Co., SaSann FrancisFranciscoco..

WilliamsWilllami,, N.. C.C. , anandd M&dsen_on,, J.J. HH.. Jr. (1959)(1959) , ~Late CretaceouCretaoeouss stratisrtphzStratigraphy ofof thethe CoalvillCoalvillee AreaAre!,, l1!!!!.Utah. GuidebooGuidebookk ttoo ththee GeGeologologyy ofof ththee _atohWasatch anandd UinUinttaa lMountainfountainas TraneitioTransitionn Area, IntermountaiIntermountainn AssocAssoc.. PetroPetroleul eumm GeologistGeologist.s TTententhh AnnualAnnual FieldField ConterenConferenceoe..

Wood,Wood, H.. E.E. , etet.. alal.. (1(1941)941),, NomenclaturNOlllBno14turee andand Correlation!l!Correlation of ththee NNortorthh AmericfIlAmerican ContinentaContinentall TertiaryTertiary.. GeoGeoll.. Soc.Soc Am.Am. Bull.Bull.,, vol.vol. 52,52, nnoo.. 1,1, pppp.. 11-48-48..

WoodWood,, lim.Wm. J.J. (1953)(1953 ),, AreaAreal! GeologGeologyy ooff ththee CoalvilleCoalville VicinityVioinity,, SSummi1lllI1litt Cgunty,County, l!lI!!.Utah. M.. S.S. ThesisTh ..i e,, UnivUniversitersity ofof Utah.Utah.

WyomingWyoming GeolGeol.. Assoc.Asooo.,, GuidebookGuidebook ttoo ththee FiftFifthh AnnuaAnnuall FielFieldd Conterenoe.Conference.

Yen, T.. Cc.. (1948)(1948),, EocenEooenee FresFresh )latorWater MblluscMollusoaa frofromm Wyomingm m1ng .. Jour.. PalPaleoneon­­ tologytology,, volvol.. 2222,, pp.. 634634-640- 640.. _ _ ~~(~(1951)1~9~51) ,, FresFroehh WateWatorr MoIfelluskllUSk!s ofof CretaceousCretaceous As!Age f!2!!!from MontanMont ~a ean d Wypming.Wyoming. uU.. S.S. GeoloGeologicagioall Survey ProfProf.. PapePaperr 233233-A-A, parpartt 22.. 104104

Yen,Ian, T. c0. (1(1952a)952&),, l.!:!I!!graph ^U!'Iatorr lbifellusea11uscllln FIMAFaunj frem.lllfrom jn UUppepperr Crot"'OO1lJ!Cretaceous Porca]]pp3-tePorcellanite naIrnear ~aSaggee Junction,, WyomAAg.Wyoming* Am.Am. JJourour. SScienceOience,, vol.vol. 250 , pppp.. 344-359,344-359, May.Kay.

__=(1952b (1952b)) , ~!!!!!!!Age of the B.~Bear RiverRiver fformationO!1llltiotl,, VI,yom1..=y;Wyoming.. Geol. Soc.Soc. Am.Am. BullBull..,, vol.vol. 6633,, pp. 757757-764-7 4.. ___ = (1(1952c)952c), EsologicolEcological InterprotInterpretationatioruos ofof UppeUpperr CretaceousCretaceous DepoDeposit,itos l!!£near SaSaggee JunJunctionction,, WyomingWx9m1ng.. GeoGeoll.. Soc.Soc. Am.Am. BullBull.. , vol.vol. 63,63, p. 1317.1317.

_--;= (1(1954a)954",),, Non-MarinNon-Marinee lbMollusk11uakas !!!of !£!Late CretaceouCrotacoouas ~Age fromfrom VI,yoming,Wyoming, Utah,Utah, !!!l!and Color¥l9'Colorado. Uu.. s.S. CeoGeological ogicall Survey ProfPref.. PapePaperr 254-B.254-B.

__."... „ (1954b).(1954b), ~Age 2fof .!:h!.the BBeaear River fonnation.formation. Am.Am. Assoc.Assoc. PetroleumPetroleum Coolog1.otGeologists. Bull.Bull.,, vol.vol. 38,33, no. 11,11, pp.pp. 2412-2413.2412-2413.