Many of the topics that will bediscussed are controversial, but thestratigraphic units selected are believed to be in the most use bygeologists studying the west side ofthe San Joaquin Valley. The variousunits are described chronologicallyfrom youngest to oldest, as has beendone in some previous guidebooks.For ease of reference, each formation is described under the followingtopics in the same order: 1) typelocality, 2) characteristics and lithology, 3) fauna and age, 4) strati-graphic relationships, 5) divisions,and 6) oil and gas. The fauna andage section has been written byRobert Blaisdell.

TYPE LOCALITYAND ACCEPTANCE

Under type locality it will befound that some of the names areinformal without a definitely described type section. Also, some ofthe stratigraphic units are mainlyfaunal zones without a characteristiclithology. Many of the names wereprobably used by petroleum geologists before they appeared in print.Equivalent names to the stratigraphicunit discussed are considered under5) divisions.

The degree of acceptance of theformations and members named isplaced in three categories: 1) formalunits accepted by the U.S.G.S. in theLexicon (1966), such as: Tulare,San Joaquin, Etchegoin, etc., 2) informal units listed in the Lexicon(1966), such as: Antelope shale,McDonald shale, Devilwater silt-stone, etc., 3) units not listed by theU.S.G.S., but used locally and informally are placed in quotationmarks, such as: “Button bed,” “Phacoides sand,” “Salt Creek shale,”“Oceanic sand,” etc.

STRATIGRAPHIC NOMENCLATURESince the units picked are not all

accepted as formations, a brief mention of the stratigraphic nomenclature may be in order. The Pleistocene and Pliocene units used: theTulare, San Joaquin, and Etchegoin,have all been accepted as formalformation names. The Miocene unitsused, on the other hand, are members, or smaller stratigraphic units,that are mostly informal. The Miocene has been divided into twoformal formations: 1) the MontereyFormation replacing the term Mancopa shale, which has been abandoned, and 2) the Temblor Formation.

The Monterey Formation is mostlyshale in the type section of its members: Reef Ridge, Antelope, McDon

aid, Devilwater, and Gould. Lithologically, these members can beseparated in their typical areas, butthey are carried beyond their lithologic limits by micro faunal assemblages. Beyond the limits of thefaunal zones, new member namesare given. As an example, typicallythe Reef Ridge is a blue shale or adiatomaceous shale, the Antelope isa gray-brown rhythmically beddedsiliceous to cherty shale, the McDonald a massive chocolate brown silt-stone, the Devilwater a grayishsiltstone, and the Gould is a massivesiliceous shale. To the north, theAntelope and the McDonald members are included in the McLurebrown shale member because theycannot be separated by either lithology or fauna.

The Temblor Formation is mostlysand with some shale in the typesection of the Temblor Ranch. Themembers and beds included underit are: the “Button bed”; Mediashale member; Carnerous sandstonemember; Santos shale member,which includes the “Upper Santos,”Agua sandstone, and “Lower Santos”; the “Phacoides”; and “SaltCreek shale.” The Vaqueros in theSalinas Valley is the approximateequivalent to the Temblor in the SanJ oaquin Valley. However, whenboth the terms are used in the SanJoaquin Valley, the Temblor refersto the Turritella ocoyana zone orthe Saucesian and younger beds,whereas the Vaqueros refers to theTurritella inezana zone or the Zemornan beds. It will be found that thetype locality for a11 Miocene unitslisted, except the Reef Ridge, is inthe Chico Martinez area which willbe visited on the field trip.

It is believed the OligoceneTumey should be treated as a formation, although in places north ofDevils Den it has been consideredas a member of the KreyenhagenFormation.

The Upper Eocene consists of twoformations that interfinger into eachother: ii Kreyenhagen Shale in theCoalinga district in the north, and2) The Tejon Formation of mostlysands and some shale at the southend of the valley. The Point of Rockssandstone is a tongue of the TejonFormation in the Kreyenhagen Shalethat extends as far north as PyramidHills. On the other hand, the Welcome formation (Upper Kreyen.hagen) and the Canoas shale aretongues of the Kreyenhagen aboveand below the Point of Rocks.

SEQUENCESUnfortunately, some formations

like the Temblor have unconformities within them, or some formationsare a part of all of a certain succession of lithologies between unconformities. For this reason, and alsoto attempt to formulate a strati-graphic pattern for this area, theconcept of sequences is introducedfor the westside, although its application is somewhat speculative. Sincethis term has not been used previously in the literature on the WestSide, it is explained more fullybelow. A sequence is defined as thebeds between the more importantunconformities and their continuation into conformable beds. The termsequence was used by Sloss, Krumbein, and Dapples (1949) for strata

‘Manuscript received Feb. 1968.2Getty Oil Company, Bakersfield, Calif.3Standard Oil Company, Bakersfield, Calif.

STRATIGRAPHY OF THE WEST SIDE SOUTHERN

SAN JOAQUIN VALLEY’

CHARLES D. Foss2 and ROBERT BLAISDELL3

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between major regional unconformities in the interior of North America.Compared to that, the sequencesreferred to here are local and ofshort duration, but possibly containequivalent thickness of strata.

The sequences have a certaintectonic and depositional succession.On the West Side there seems to betwo types of sequences: 1) a thinsequence with a thin erratic postunconformity sand, a middle shale,and a thick but truncated upperpre-unconformity sand; 2) the thicksequence is thicker, but otherwisesimilar with the addition of a middlesand incased in an upper and lowershale, and the upper pre.unconform.ity sand is thin or absent.

The stratigraphy of the West Sideis tentatively divided into 9 sequences listed below:

1. Tulare thick sequence—TulareFormation.

2. Pliocene thick sequence — SanJoaquin and Etchegoin Formations.

3. Feed Ridge thin sequence —

Reef Ridge.4. Monterey thick s e q u e n c e—

Antelope, McDonald, Devilwater andGould members of the MontereyFormation, and the “Button bed”unit of the Temblor Formation.

5. Saucesian thick s e q u en c e—Media, Carneros, “Upper” Santos.

6. Lower Santos thin sequence—Agua and “Lower” Santos.

7. Salt Creek thin sequence —

“Phacoides” and “Salt Creek.”8. Oligocene thin sequence —

Tumey and “Oceanic.”9. Kreyenhagen thick sequence

Kreyenhagen, Point of Rocks, andCanaos.

The names are temporary and, ifthe concept is usable, more formalnames may be presented.

Thick sequences are characterizedby a thick middle sand incased inshale. Examples of a thick sequenceare as follows: The Kreyenhagensequence has the erratic post unconformity sand, the Mabury; and thethick midle sand, the Point of Rocks,incased in the Canoas and Kreyen.hagen shales. There is no pre.unconformity sand. The Saucesiansequence is similar with the middlesand, the Carneros, incased in the“Upper” Santos and Media shales.The Monterey sequence has the postunconformity sand, the “Buttonbed” and, in places, the numerousoverlapping Devilwater sands. Themiddle sand, the Stevens, is incasedin the Antelope shale. There is nopre-unconformity sand. In the Plio

cene sequence the Bates and othersands are the post unconformitysands. The middle sandy section, theUpper Etchegoin, is incased in theLower Etchegoin and San Joaquinclayey sections. The Tulare sequenceconsists of fluvial sands between theupper and lower lacustrine beds.

The significance of the middlesands is that they were depositedwhen the West Side and the Tem.blors were a deeply sinking basinand the sands were derived fromuplifts elsewhere.

The thin sequences, except for theOligocene sequence, are character.ized by a thick and rapidly truncatedpre.unconformity sand. Examples ofa thin sequence are as follows: TheSalt Creek sequence has the erraticbasal post unconformity “grit” fol.lowed by the “Salt Creek shale,”and the thick pre.unconformity sand,the “Phacoides” or “Belridge 64.”The Lower Santos sequence is similar with the basal sand, the “Bloe.mer” followed by the “Lower” San.tos shale and the pre-unconformitysand, the Agua. The Reef Ridgesequence also has basal sands followed by shale and the pre-uncon.formity sand, the Olig.Potter. On thecrest of the Temblor the probablycorrelative fine Santa MargaritaSand is overlain by the pre-uncon.formity granite conglomerate. In thecase of the Oligocene sequence, thebasal post unconformity sand, the“Oceanic” is the most prominent.This is followed by the Tumey shale,but the pre-unconformity sand ismissing.

The significance of thin sequencesands is that they are derived fromthe uplifts of the Temblor Rangethat produced the unconformities.

UNCONFORMITIESSince the principle unconformities

are the basis for separating the sequences, a brief mention will bemade of them.

The Eocene unconformity is themost prominent in the south whereit is on basement and disappears tothe north of Coalinga where thebeds are more or less conformable.This unconformity is a result of uplift in the Transverse Range. Thebase of the Oligocene unconformityis also more prominent in the southas at Belgin Anticline and disappearsnorth of Devil’s Den where it is conformable on the Upper EoceneKreyenhagen Shale.

Most of the Miocene unconformities, on the other hand, are more

prominent in the north and disappearin the southern portion of theTemblor Range where the Mioceneis conformable, except for the ReefRidge. The general tendency is forthe progressively younger Mioceneunconformities between sequences tomigrate southward, closing off theseaway across the southern portionof the Temblor Range. The variousMiocene unconformities truncateeach other so their original distribution is altered.

The base of the Miocene unconformity is a transitional type, beingpresent in both the TransverseRange at the south end of the valleyand in the central Temblor Range.

The base of the Lower Santos,base of the Saucesian unconformities, are present in the central Ternblor Range and adjacent areas. Themost prominent one is the base ofthe Upper and Middle Miocene unconformity which shows prominentoverlapping and truncation in thecentral Temblor Range area. Thebase of the Reef Ridge unconformityis present mainly in the southernTemblor Range.

The base of the Pliocene unconformity is present on the flanks ofthe southern and central TemblorRange, but it is especially prominentin the Cymric Field. North of Devil’sDen it is represented by conformablebeds.

The base of the Tulare unconformity is present mostly around theflanks of the valley and such upliftsas Lost Hills and South Beiridge.

TYPES OF SAND BODIESIn summary, it appears there are

mainly three types of sand, eachwith its particular type of geometry:1) the post unconformity sand iseither overlapping or erratic, 2) thepre-unconformity sand is wedgeshape, often becoming coarser atthe top, 3) the middle sand is athick series of sands that interfingersinto shale.

CORRELATION PROBLEMSCorrelation still remains the big

gest problem. This makes the discussion of stratigraphic relationshipssomewhat speculative and subject todifferent interpretations. For instance, do the Potter, Olig, andFitzgerald sands belong in the topof the Reef Ridge Miocene, in thebasal Pliocene, or both? A choicehas had to be made in order tosynthesize the stratigraphy and toknow which unit to describe themunder.

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FORMATAn outline of the items discussed

under the various stratigraphic unitsfollows. However, not all items arediscussed under each unit.

STRATIGRAPHIC UNIT (AGE)TYPE LOCALITY.

Type area, type section, or typewell. Formal, informal, or local use.What named after, named by whom,subsequent revisions, and references.

CHARACTERISTICS AND LITHOLOGY.What distinguishes the formation.

Boundaries, internal markers. Lithol.ogy at the type section, lithology ingeneral, and lithofacies.

FAUNA AND AGE.Discussion of megafossil zones

and microfossil zones with age determination.

STRATIGRAPHIC RELATIONSHIPS.Distribution. Position in sequence.

The area of maximum thickness andthick axis with the conformablyoverlying and underlying strati-graphic units and those it gradesinto laterally. Toward the edges,wedging, onlapping unconformably,amount of onlapping or duration ofthe unconformity, and beds truncated. Where unit is truncated byan overlying unconformity. Outcrops.

DIVISIONS.Equivalent names for the same

unit. Subdivisions of the unit. Faciesnames. Named oil sands.

OIL AND GAS.Trends and gravity variations.

TULARE FORMATIONPLEISTOCENE

TYPE AREA: East Flank of Kettle.man Hills adjacent to Tulare Lake.F. M. Anderson (1905) p. 181. Typesection suggested as La Ceja inSection 35-21S/17E by Woodring,Stewart & Richards (1940) pp. 13-26. Formally accepted.

CHARACTERISTICS AND LITHOLOGY:The main characteristics are buffcolored sediments and fragments ofolder sediments. The type area consists of 1000 feet of gypsiferoussands and clays. In general, it consists of fiuvial sands which are silty.pebbly, and conglomeratic and, inthe upper and lower portions, arelacustrine clay, silt, fine grainedsandstones. tuff, limestones. gypsum.and diatomite. Near the front of theTemblor Range it consists of fragments of older sediments.

FAUNA AND AGE: The Tulare Formation is non-marine in origin and

considered Pleistocene in age fromstratigraphic position and containedMollusca. In some places the Tularecontains abundant, well preserved,re-cycled Eocene and Miocene fora.minifera.

The boundary with the underlyingSan Joaquin Formation in the Kettle-man Hills area, which has beenregarded as the type region, hasbeen placed at the top of the “UpperMya” molluscan assemblage of theSan Joaquin and below the “Lower”Amnicola Molluscan assemblage ofthe Tulare.

Beds of the Tulare contain agoodly number of Mollusca representing fresh water snails and mussels and a few brackish water clams.Fresh water diatoms are also present.The fauna have been divisible inthe Kettleman Hills area into an“Upper” and a “Lower” Amnicolaassemblage, both assemblages characterized by an abundance of freshwater gastropods, belonging to theAmnicolidae (Flumincola, Pyrgulopsis, Calipyrgula, Littoridina, Amnicola, Hydrobia and Brannerillas).For a listing of the mollusks and thediatoms, the reader is referred toWoodring, et al (1940( listing opposite page 78, and to Arnold (1909)on pages 91 to 101.

STRATIGRAPHIC RELATIONSHIPS:

This formation includes the entireTulare sequence. It occurs mainlyon the west side of the San JoaquinValley with the thick axis of around4500 feet extending from San Emgidio Nose through the KettlemanHills, along which it is conformablyoverlain by the Alluvium and underlain by the San Joaquin Formation.Eastward, it grades into the KernRiver Formation. To the west, theTulare unconformably overlaps formations as old as the Eocene. Itoutcrops in the Temblor foothills,Kettleman Hills, at North Belridge,Elk Hills, etc.

DIvISIoNS:

CORCORAN CLAY MEMBER. UpperTulare lacustrine member. Type wellis a test hole in Section 15-15S/14E.It is 50-120 feet thick and covers4000 square miles. Frink and Krues(1954). pp. 2357-2371.

“AMNICOLA SAND” is an importantoil sand named after the numeroussmall gastropods that are found inthis sand.

OIL AND GAs: 12 to 15° gravityoil is found in a belt extending fromthe South Lost Hills. S. E. NorthBelridge. South Beiridge, Cvmric,McKittrick to Midway Sunset. The

oil is principally in the lacustrinebeds of the lower Tulare where itoverlaps San Joaquin, Etchegoin,Reef Ridge, and Antelope oil bearingsands. Possibly it is a lake shoreline accumulation.

Gas is trapped by the pinch outof thin gas sands in the DudleyRidge Field.

SAN JOAQUINFORMATIONUPPER PLIOCENE

TYPE AREA: Eastside of the northdome of Kettleman Hills Section23-22S/18E. Named by F. M. Anderson (1905) p. 181. It was furtherdefined by Barbat & Galloway(1934 ( pp. 476-499. Formally accepted.

CHARACTERISTICS AND LITHOLOGY:

Characterized by blue and green finegrained rocks that are more persistent than the overlying or underlyingformations. Principally fine grainedsilty sands, silt, and clay. Somewhatrhythmic, green, barren, varvedclays; blue Mya.Elphidium clays;and the brown Pecten clays.

FAUNA AND AGE: The San JoaquinFormation is predominantly marinein origin and many of the coarsergrained beds contain marine molluscan fossils. Some of the finer grainedbeds appear to be non-marine inorigin; at least marine fossils havenot been found in many of them, andthe remains and land plants andfresh water shells are present insome. The San Joaquin is consideredlate Pliocene and, possibly, earlyPleistocene in age from stratigraphicposition and contained Mollusca.

The largest marine faunas aregenerally found in sand, sandstoneand conglomerate. These beds aredistinctive by the fossil and lithiccomponents, but most of these showstratigraphic change along strikeand, therefore, the only memberrecognized is the Cascajo Conglomerate at the base of the formation.

Contact with the overlying Tularois placed above an “Upper Mya”molluscan assemblage. There areseveral other faunule zones withinthe San Joaquin characterized byspecies of Pecten. Acila. Anadara,Mva, Trachycardium, Dendrasters(sand dollars ( and numerous representative gastropods. Some of themore characteristic species are:Pecien coaliizgensis, Ostrea vesperlina and Dendraster coalingensis.For a more complete listing of themollusks the reader is referred to

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Woodring, et al (1940) listing opposite page 78. A listing of diatomsrecorded from the formation may befound on page 41 of Woodring.

STRATIGRAPHIC RELATIONSHIPS:This formation is the upper shaleypart of the Pliocene sequence. Itoccurs mainly on the West Side ofthe San Joaquin Valley, with thethick axis of around 4200 feet extending from San Emigdio nosenorthward through the CoalingaDistrict along which it is conformably overlain by the Tulare andunderlain by the Etchegoin. Eastward, it grades into the Kern RiverFormation. It wedges to the westand, in places, overlaps on to theMiocene. Also to the west, it istruncated by the basal Tulare unconformity.

DIVISIONS:CASCAJO CONGLOMERATE Member

occurs in the Kettleman Hills. Woodring, et al (1940).

OIL AND GAS: The oil is heavy onthe west and grades to gas in thecenter of the basin. It is 15-23°gravity at Midway Sunset, 18-36°at Buena Vista Hills, 18-39° at ElkHills with a gas cap. The center ofthe valley has gas sands from Semitropic to Palorna. Possibly theseare shore line sands and sands onthe flanks of growing structures.

ETCHEGOINFORMATIONLOWER PLIOCENE

TYPE AREA: Etchegoin Ranch andvicinity, NW/4 Section 1-19S/15Eat the north end of the CoalingaField. Named by F. M. Anderson(1905) pp. 178-181. Barbat & Gallo.way (1934) restricted the Etchegoin.Formally accepted.

CHARACTERISTICS AND LITHOLOGY:Massive blue and brown sandstones,poorly sorted blue or bluish grayshales, and pebble conglomerates.in places variable, making correlations difficult. The Lower Etchegoin(Jacalitos) is more shaley and ithas a basal sand, also some diatomiteand punky shale.

FAUNA AND AGE: The EtchegoinFormation is predominantly marinein origin and strata of the formationcontain marine Molluscan faunalassemblages that lend themselves tofaunule zonation. However, some ofthe beds within the formation docontain fresh water mollusks or amixture of marine and fresh watermollusks. The Etchegoin is consid

36

ered early Pliocene in age fromstratigraphic position and containedMollusca.

At Kettleman Hills Woodring, etal (1949) have delineated nine milluscan faunule zones within theEtchegoin. The most satisfactoryhorizon is these is the Littorinafaunule assemblage which is near thetop of the formation. This faunuleassemblage is used to help delineatethe Etchegoin from the overlyingSan Joaquin.

Some of the more characteristicmolluscan fossils found in the Etchegoin are: Arca trilineata, MytilisCoalingensis, Liuorina m a r i a n a,Pseudocardium gabbi, Pseudocardium densatum and Siphonalia kettlemanensis. For a more complete listing of the mollusks the reader isreferred to Woodring, et al (1940)listing opposite page 78. A listingof diatoms recorded from the formation may be found on pages 67, 75and 78 of Woodring (1940).

STRATIGRAPHIC RELATIONSHIPS:This formation includes the middlesand, the lower shale, and the basalsand part of the Pliocene sequence.It occurs mainly on the westside ofthe San Joaquin Valley with thethick axis in the center of the valley,reaching a maximum thickness of4730 feet at North Dome KettlemanHills. Northward, the thick sectiontrends between Pyramid Hills andCoalinga, indicating a probable connection with the sea. In this centralarea it is conformably overlain bythe San Joaquin and underlain bythe Reef Ridge. Eastward it gradesinto the Kern River Formation. Itwedges to the west and, in places,is overlapped by the San Joaquin.Also to the west, it truncates bedsas old as the Cretaceous (Coalinga)and, in turn, it is truncated by thebasal Tulare unconformity.

DIVISIONS:

JACALITOS FORMATION named fromJacalitos Creek, 21S/15E, south ofCoalinga, by Arnold and Anderson(1908). It is considered equivalentto the Lower Etchegoin.

“BITTERWATER CREEK FORMATION”named from Bitterwater Creek (Section 32, 33-11N/24W) by Dibblee(1962). It is a semi-siliceous shalefacies up to 3000 feet thick, gradingnorthwest into marine sandstones.

“PANORAMA HILLS FORMATION.”Non-marine pebble gravel in lowerpart grades southeast through marinesandstone into the Bitterwater shale.It is adjacent to the San Andreasfault. Dibble (1962) S.J.G.S. Guide-

book “Geology of The Carrizo Plains& San Andreas Fault.”

OIL SANDS in the Upper Etchegoin are the Bitumen, Wilhelm, andGusher sands; and in the LowerEtchegoin, Calitroleum, etc.

BATES SAND, the basal Etchegoinsand on the east flank of Devil’s Den.

FITZGERALD SAND is the basalEtchegoin sand in the Cymric area.

OIL AND GAS: Lower gravity (13-18°) oil is found near the truncationand shore lines, and higher gravity(18-40°) oil basinward. Gas is foundin the center of the basin. Oil andgas trends are similar to the SanJoaquin.

MONTEREYFORMATION

REEF RIDGE SHALE MEMBERUPPER MIOCENE DELMONTIANTYPE LOCALITY: At the base of

the Reef Ridge north of the PyramidHills Field. Named by Barbat andJohnson (1933), Gester and Galloway (1933) pp. 1174-1176. It outcrops on the flanks of the Diabloand Temblor Ranges. Restricted bySiegfus (1939). Formally acceptedas a formation, informally as amember of the Monterey.

CHARACTERISTICS AND LITHOLOGY:

Blue shale in the vicinity of the typerection. White, gray, or brown diatomaceous sandy, thin bedded shalewith poorly sorted granitic sandsand conglomerate to the south.

FAUNA AND AGE: The foraminifer,Bolivina obliqua, found in the ReefRidge, is an index fossil for Kleinpell’s (1938) Delmontian stage ofthe Upper Miocene. Some otherforaminifers reported from theReef Ridge Shale in the Belridgeand Kettleman Hills area are:Nanion beiridgensis, Nonioncila mioc e n i c a, Buliminella elegantissima,Buliminella dubia, Bulimina pseudotora, Virgulina californiensis, Virgulina subplana, Bolivina brevoir andEponides exigua.

The Chico Martinez (Belridge)diatomite of the Chico MartinezCreek area is of Mio-Pliocene ageby lithologic correlation with theBelridge diatomite in the subsurfaceat South Belridge where Elphidiumhughesi, which is common in thePliocene, has been found in theupper part of the diatomite andBolivina obliqua is abundant in thelower part.

STRATIGRAPHIC RELATIONSHIPS:This represents the entire Reef Ridgesequence. The thickest section isprobably 2200 feet in the Midway

Sunset area. In its axial area it isconformably overlain by the Etchegoin and underlain by the AntelopeShale. Eastward, it grades into theChanac. Toward its periphery it isessentially regressive with shale atthe base with an overlying preunconformity sand becoming increasingly coarse toward the top,such as the Olig, Potter, etc. It istruncated by the basal Pliocene andthe basal Tulare unconformities tothe west.

DIvIsIoNs:BELRIDGE DIATOMITE is a facies

of the Reef Ridge. Siegfus (1939).OIL SANDS are the Olig, Potter,

Lakeview, and Marvic sands.OIL AND GAS: Oil in this formation

has been found mainly in the McKittrick-Midway Sunset area.

ANTELOPE SHALE MEMBERUPPER MIOCENE-UPPER MOHNIAN

TYPE LOCALITY: Probably informally named by petroleum geologistsfrom outcrops in the Temblor Hillsadjacent to the Antelope Valley.First appeared in print in an articleby E. B. Noble (1940) on the RioBrova Field p. 1332 (fig. 1), and bySimonson and Grueger (1942) p.1611 (fig. 2) p. 1617. Informal

CHARACTERISTICS AND LITHOLOGY:This is a member of the MontereyShale and grades into the McLureShale Member to the north. Thelower Antelope is mainly cherty andsiliceous shale; whereas, the UpperAntelope has a brown shale facies, acherty and siliceous shale facies(Chico Martinez) and a sand andshale facies (Stevens).

FAUNA AND AGE: The Antelope isprobably Upper Miocene, UpperMohnian by stratigraphic position.

The foraminifers Buliminella elegantissima, Bolivina seminuda, Nonicrnella miocenica, Nonion sp.,(Jvigerina subperegrina, Virgulinasp. and Globigerina bulloides arefound in the lower part of the Antelope along with the mud pectenPecten peckami. Pecten peckami isan important subsurface fossil.

The Chico Martinez cherts (Mc.Lure of Prof. Paper 195) containrelatively non-diagnostic arenaceousforaminifers, including Cyclamminasand Trochamminas. These beds areDelmontian or Upper Mohnian bystratigraphic position.

STRATIGRAPHIC RELATIONSHIPS:This formation is in the upper partof the Monterey sequence. It contains the middle sand of the se

quence, the Stevens and the siliceousshale portion. The thickest sectionis probably in the outcrop sectionadj acent to the Midway Sunset Field,where it is conformably overlain byReef Ridge and underlain by theMcDonald shale. Eastward, it gradesinto the upper Fruitvale shale andSanta Margarita sands. It is possiblylocally unconformable with theoverlying and underlying formations.It outcrops on the eastern flank ofthe Temblor Range.

DIVISIONS:UPPER AND MIDDLE MCLURE. The

Antelope grades into the upperbrown shale and the middle siliceousand cherty shales of the McLure.

CHICO MARTINEZ apparently firstappeared in print in the S.J.G.S.Guidebook on Chico Martinez Creek(1959). It is apparently equivalentto the Upper Antelope Haplophragmoides arenaceous zone. Some geologists consider it in part Reef Ridge.This formation changes from siliceous shale and chert at the typelocality (Section 11-29S/20E) tobrown shale to the north.

STEVENS SAND was named afterthe Stevens Station on the SunsetRailroad as an informal subsurfacename. It first appeared in print inHoots (1938) pp. 701.718. The central valley Stevens sand is an inter-fingering blanket sand with a cementation barrier adjacent to the ColesLevee and Paloma Fields, possiblydue to commingling of the easternand western waters.

The westside sands equivalent tothe Stevens sand are composed of offstructure linear sand bodies. Thenorthern one goes under variousnames such as the McKittrick Stevens sand, Asphalto sands, “555”sand at Buena Vista Hills, and theElk Hills Stevens sands. In theMidway Sunset area, these sandsmay be roughly divided into: 1)upper Antelope Monarch, Contact,Gibson, Hoyt, B e v e r ly, 10.10,and Essex sands; 2) upper middleAntelope Webster, Signal, Exeterand 29-D sands; 3) lower middleAntelope Moco, Uvigerina C, Obispo,and Metson sands; and 4) lowerAntelope Republic, Williams, andLeutholtz sands.

OIL AND GAS: Oil is found in theStevens and related sands. It ishigher gravity basinward. Oil is alsofound in the fractured shales. It ismore prolific in the fractured chertfacies adjacent to Stevens sandproduction.

McDONALD SHALE MEMBERUPPER MIOCENE.LOWER

MOHNIAN

TYPE LOCALITY: Probably informally named by petroleum geologistsfrom outcrops southwest of the present McDonald Field. First appearedin print as equivalent to the Pulvinulinella gyroidinaformis zone in anarticle by Cushman and Goudkoff(1930) p. 1. This unit is within theMonterey Shale, and grades into thebasal portion of the McLure ShaleMember. It is described as a member of the Monterey Shale in Simon-son and Krueger (1942) pp. 1616.1617. Informal.

CHARACTERISTICS AND LITHOLOGY:In Temblor Range the McDonaldshale is characterized as a massivechocolate brown silty shale in contrast to the buff and tan DevilwaterGould and the siliceous well-beddedlight brown shale of the Antelope.In places, it has a cherty and siliceous shale member, and a sandmember often basal.

FAUNA AND AGE: The McDonaldis considered to be Lower Mohnianin age on the basis of its strati-graphic position and containedmicrofauna.

Upper McDonald shales are representative of Kleinpell’s (1938) Bulimina uvigerinaformis zone of thelate Lower Mohnian stage age.Some of the foraminifers found inthese upper shales are Pulvinulinellagyroidinaformis, Bolivina sinuatasinuata alisoensis, Uvigerina hootsi.In the Chico Martinez Creek area,the uppermost McDonald carries rareoccurrences of Uvigerina segundoensis.

Cassidulina monicana, Eponidesk e e n a n i, Gyroidina montereyana(obesa), Bolivina californica, Bollvina parva and Uvigerina joaquinensis are some of the foraminifersfound in the lower McDonald shales.The assemblages place these shalesin the Bolivina modeloensis zone ofearly Lower Mohnian stage age.Lower McDonald shales that werelaid down in deep water carry afauna characterized by Pulleniamoorej and Rotalia becki (see discussion by C. H. Rudel in theguidebook).

STRATIGRAPHIC RELATIONSHIPS:This formation is in the middlepart of the Monterey sequence. It isthe shale below the middle sand ofthe sequence. The thickest sectionis probably in the outcrops in theTemblor Hills adjacent to the Mid-

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4

way Sunset Field (2250 feet) whereit is conformably overlain by theAntelope Shale and underlain bythe Devilwater siltstone. Eastward,it grades into the Lower Fruitvaleshale and northward, into the lowerMcLure shale. In the northern partof the area adjacent to the TemblorRange, the McDonald forms thebasal member of the sequence withthe Packwood as the basal sand,truncating beds as old as the EocenePoint of Rocks. The McDonald outcrops along the front of the TemblorRange.

DIvIsIoNs:LOWER MCLURE. The McDonald

grades into this portion of theMcLure.

TWISSELMAN SAND type section onthe Twisseirnan Ranch in Section14-27S/18E. Heikkila and MacLeod(1951) p. 12.

PACKWOOD SAND is in the vicinityof the North Antelope Field and isnamed after Packwood Creek.

OIL AND GAS: A small amount ofoil has been produced from thePackwood sand and fractured shales.

DEVILWATER SILT MEMBERMIDDLE MIOCENE-LUISIAN

TYPE LOCALITY: Probably inform.ally named by petroleum geologistsfrom outcrops in Devilwater Creekwest of the Antelope Hills Field.First appeared in print Bailey(1939) pp. 66.71. Informal.

CHARACTERISTICS AND LITHOLOGY:It is a buff to dark gray sandy silt.stone with a greenish cast. In thevicinity of the McDonald and Antelope Hills Field it has numeroussands.

FAUNA AND AGE: The Devilwatersilt contains foraminifers typical ofthe Luisian stage of the MiddleMiocene.

The late Luisian Siphogenerinacollomi zone of Kleinpell (1938) isnot represented in the Devilwaterin the Chico Martinez Creek areabut, elsewhere, in the subsurface itis characterized by the foraminifers:Valvulineria californica ss., Sipho.generina collomi, Baggina californ.ica, Bolivina advena striatella, Anomalina salinasensis and Pullen iamiocenica.

The upper portions of the Devil.water silt in the Chico MartinezCreek area contain foraminifers indicative of the Siphogenerina nuciformis zone of the Luisian. Someof these are: Baggina californica,Bolivina advena striatella, Bolivinaimbricata, Anomalina salinasensis,Dentalina quadrulata, Hemicristel

lana beau, Pullenia miocenica, Siphogenerina nuciformis, Valvulineriacalifornica.

Foraminifers in the lower portions of the formation in the ChicoMartinez Creek area are representa.tive of the early Luisian, Siphogener.ma reedi zone. Some of these are:Bolivina advena ornata, Bolivinacalifornica, Valvulineria californicass and var. obesa, Siphogenerinareedi and Siphogenerina nuciformis.

STRATIGRAPHIC RELATIONSHIPS:This formation is in the upper

lower part of the Monterey sequence.The thickest section, up to 1500feet, is probably the one west ofthe Midway Sunset Field, where itis conformably overlain by the McDonald shale and underlain by theGould Shale Member. Eastward, itgrades into the Round Mountainsilt and northward, into non-marinebeds. The thick interval of overlapping sands in the McDonald-Ante.lope Hills area indicates the ratherlong duration of the base of theupper and middle Miocene unconformity. It outcrops in the TemblorHills.

DIvIsIoNS:ALFERITZ FORMATION (informal)

named by Van Couvering and Allen(1943) pp. 496.500. This is equva.lent to the Devilwater. In spite ofthis being the first description of thesurface beds, it is little used. Devil’sDen District.

OIL SANDS in the McDonald Antidine Field are the “Theta” or “2ndDevilwater Sand” and the “Tolco”or “7th Devilwater Sand.”

OIL AND GAS: The oil productionis mostly limited to the sands mentioned above in the McDonald Field.There is some gas at Antelope Hillsand oil in the Foraminite zone atRailroad Gap.

GOULD SHALE MEMBERMIDDLE MIOCENE-RELIZIAN

TYPE LOCALITY: Probably infor.mally named by petroleum geologists from Gould Hill south of ChicoMartinez Creek. The type localityextends from center W/2 Section14-295/20E to southeast side ofChico Martinez Creek. Cunninghamand Barbat (1932) pp. 417-421.

CHARACTERISTICS AND LITHOLOGY:The most characteristic lithology ishard, silicified, locally cherty andresistant platy tan shale. In someplaces, it is more massive and siliceous. The siliceous shales distinguish it from the Devilwater. AtBelgian Anticline it is brown silt-stone. Where it is a clay shale or

siltstone, its presence is determinedby paleo or electric log correlations.The thicker sections have the siliceous shale facies.

FAUNA AND AGE: The Gould Shaleis placed in the late Relizian stageof the Middle Miocene, both by thecontained foraminifers and strati-graphic position.

Such foraminifers as Bagginarobusta, Bolivina imgricata, Gyroidma reliziana, Nonion costiferum,Siphogenerina branneri and Valvulineria californica vars. obesa andappressa found in the Gould arerepresentative of the Kleinpell’s(1938) Siphogenerina branneri zoneof the Relizian.

STRATIGRAPHIC RELATIONSHIPS:This formation is in the lower partof the Monterey sequence. The thick.est section of up to 1500 feet isprobably west of the Midway SunsetField. It is conformably overlain bythe Devilwater and underlain by the“Button bed.” Eastward, it gradesinto the Round Mountain silt.

SUBDIvIsIONS:LAYMAN 2 SAND is productive at

the McDonald Field.OIL AND GAS: Oil production is

limited to the above sand.

TEMBLOR FORMATION“BUTTON BED” MEMBERBASAL MIDDLE MIOCENE

TYPE LOCALITY: Carneros Creekis given by Heikkila and MacLeod(1951) p. 10, as the type locality.It was first mentioned in print byF. M. Anderson (1905) p. 170, whosaid it was the top member of theTemblor. It is named after the button.like sea urchins Scutella merriami.

CHARACTERISTICS AND LITHOLOGY:The fossil mentioned above is themost characteristic feature at thetype locality, but these are notpresent in many places. It is amedium gray to brown massive sand.

FAUNA AND AGE: Abundant speci.mens of the small, “button-like”echinoid. Scutella merriami, as wellas the characteristic Pecten estrellanus and Pecten andersoni, occurin the Button Bed sands. The Mollus.can assemblages, referable to theMolluscan “Turritellaocoyana” zone,as well as some of the microfossilsfound in the siltier parts of thestratigraphic unit, place the unit inthe early Middle Miocene.

Some of the foraminifers foundin the stratigraphic unit are: Bolivina advena striatella, Non ion costi

38

jerum, Nonionella miocenica, Valvulineria miocenica, Siphogenerinabranneri and Siphogenerina hughesi.The foraminifers are characteristicof the Siphogenerina hughesi zoneof Kleinpell (1938). AbundantSporbo (phosphatic oolites) are alsofound in the siltier parts of thestratigraphic unit.

STRATIGRAPHIC RELATIONSHIPS:This is the basal portion of theMonterey sequence. The thickestsection is probably 800 feet in theoutcrops in Sections 17, 20, 21.27S/18E. It is conformably overlain bythe Gould Shale and underlain bythe Media Shale, and grades intoGould Shale. It onlaps beds as oldas the Eocene Point of Rocks. Inthe outcrop it is an erratic sandstonevarying from zero to 800 feet from26S/17E to 29S/20E. In the sub.surface it appears to consist of several basal transgressive sandstones.

DIVISIONS:None.OIL AND GAs: Oil is produced in

the North Antelope and AntelopeFields where ~t truncates and overlaps the Agua sand. Oil is also foundat the McDonald Field.

MEDIA SHALE MEMBERLOWER MIOCENE-UPPER

SAUCESIANTYPE LOCALITY: First mentioned

by Cunningham and Barbat (1932)pp. 417-421. Probably named afterMedia Agua Creek west of the McDonald Field. Informal.

CHARACTERISTICS AND LITHOLOGY:It ranges from a platy tan siltyshale to a light colored siliceousshale. The most characteristic feature in outcrop is the presence ofnumerous 3 foot buff colored limestone beds.

FAUNA AND AGE: The foraminifersof the Media shales are representative of Kleinpell’s Uvigerinellac’besa zone of the late Lower Miocene Saucesian stage. Some of themore characteristic foraminifers are:Bulimina inflata alligata, Cibicides/loridanus, Eponides mansheidi, Nodogenrrina koina, Nodosaria parexi.us, Nonion costiferum, Plectofrondi.cularia miocenica directa, Planulinaappressa, Robulus simplex, Uvigerinella obesa impolita and Siphogenerina transversa.

In the Chico Martinez Creek areathe first 50 feet of a sandy silt interval referred to as Media, which underlies the Button Bed sand in thearea, contains Lower Relizian Siphogenerina hughesi zone foraminifers. Some of the species noted are:Anomalina salinasensis, Uvigerinella

californica, Valvulineria miocenciaand Siphogenerina branneri. NoSiphogenerina hughesi were found.

STRATIGRAPHIC RELATIONSHIPS:This is the upper part of the Sauce-sian sequence. The Media is thickest in the Temblor Range whereCarneros is thin or absent and itrests directly on the “Upper” San.tos shale. In Cedar Canyon, it is2300 feet thick. In the axial area itis conformably overlain by the“Button bed” and underlain byeither the Carneros sand or “Upper”Santos shale. It grades into theCarneros sand and, on the eastside,into the Freeman silt. It is unconformably truncated by the “Buttonbed” in the Antelope Hills and otherareas. It outcrops on the flanks ofthe Temblor Hills.

DIVISIONS:None.OIL AND GAS: None.

CARNEROS SANDSTONE MEMBERLOWER MIOCENE SAUCESIANTYPE LOCALITY: Carneros Creek

west of the Chico Martinez OilField. Cunningham and B a r b a(1932) pp. 417-421. Probably firstnamed by H. G. Schenck, May andGilboe (1931). Informal.

CHARACTERISTICS AND LITHOLOGY:The lithology varies from a veryhard lumpy calcareous sandstone toa well-bedded platy calcareous sandstone to a buff colored friable sandstone.

FAUNA AND AGE: Pecten miguelen.sis and Scutelki merriami are someof the more characteristic mollusksfound in Carneros sands. The Molins assemblage is relatable to theMolluscan “I urritella ocoyana” zoneand perhaps within the “VaquerosTemblor Transition” of Loel andCorey. Stratigraphic relationship ofthe Carneros (lying between the twoSaucesian stage age shales — theMedia and the Upper Santos) placesthe unit in the Lower MioceneSaucesian stage.

STRATIGRAPHIC RELATIONSHIPS:This is the middle sand in theSaucesian sequence. It is incased byMedia and “Upper” Santos shale.There are three bodies of Carnerossand: 1) a northern one extendingas far south as North Belridge witha maximum thickness of 2390 feetin the Bates area; 2) the middle ormain Carneros sand body extendingfrom the type section to Elk Hills,with a maximum thickness of 2000feet; 3) the southern one in theTemblor Hills west of MidwaySunset, extending from Crocker

Canyon to the Pioneer area, with amaximum thickness of 5000 feetThe Carneros is overlain and gradesinto the Media shale, and it is underlain and grades into the “Upper”Santos shale. It outcrops in theTemblor Range.

DIVISIONS:

ANDERSON SAND in the Welportarea is probably equivalent to the1st and 2nd Carneros to the south.

WESTON 3 SAND in the Welportarea is probably equivalent to the3rd Carneros sand to the south.

OIL AND GAS: The middle or mainCarneros sand body has the bulk ofthe oil from fields such as Salt Creek,Welport, Railroad Gap, and ElkHills. Railroad Gap has the largestgas cap. The southern sand body inthe Temblor Hills has the thickestsands but only small fields with20-30° oil. Also the northern sandbody has only small accumulationsof 12-23° oil.

“UPPER” SANTOS SHALE MEMBERLOWER MIOCENE-LOWER

SAUCESIANTYPE LOCALITY: Santos Creek,

Gester and Galloway (1933) andMay and Gilboe (1931). The term“Upper” Santos shale was mentionedby Goudkoff (1934). Santos informal. “Upper” Santos local usage.

CHARACTERISTIC AND LITHOLOGY:Light gray shales with thin sandlenses, and tan, platy, siliceous andcalcareous shales with lenticularlimestones and sandstones. Usuallyless silty than the Media shale.

FAUNA AND AGE: The microfaunaof the “Upper” Santos shales represent Kleinpell’s (1938) Siphogenerma transversa and Piectofrondiculana miocenica zones of the LowerSaucesian stage of the Lower Miocene.

Bolivina marginata adelaidana,Cibicides americanus, Siphogenerinatransversa, Siphogenerina tenua, Siphogenerina mayi, Baggina robustavar., abundant Sporbo (phosphaticoolites) and fish remains are someof the microfauna normally foundin these shales.

STRATIGRAPHIC RELATIONSHIPS:This is the lower shale of the Sauce-sian sequence. The maximum thickness of 1500 feet occurs in theBitterwater Creek outcrop area wherelittle, if any, Carneros is present.It is conformably overlain andgrades into the Carneros sandstone.In places, it is overlain by the Mediashale. In the axial area it is underlain conformably by the Agua sand.

59

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It also unconformably overlaps bedsas old as the Tumey shale. It outcrops in the Temblor Hills.

DIVISION:

None.OIL AND GAS: None.

AGUA SANDSTONE MEMBERLOWER MIOCENE-UPPER

ZEMORRIANTYPE LOCALITY: Named informally

in an abstract by Clark and Clark(1935) p. 137, with no type sectiongiven, but that it occurred betweenCarneros Creek and Cedar Canyon.Named after Media Agua Creek.Heikkila and MacLeod (1951). In.formal.

CHARACTERISTICS AND LITHOLOGY:This sandstone is medium to coarsegrained and gritty with muscoviteand glauconite.

FAUNA AND AGE: Bulimina camerosensis, Buliminella subJusiformis,Siphogenerina transversa, Siphogenerina mayi and Uvigerinella sparsicostata are found in the shale andsilt interbeds in a sand body in theChico Martinez Creek in the approximate stratigraphic position of theAgua sand of Media Agua Creek.This fauna is representative of theUvigerinella spars icostata zone ofKleinpell, which is the upper divisionof the Zemorrian stage of the LowerMiocene.

STRATIGRAPHIC RELATIONSHIPS:This is the pre-unconformity sandin the Lower Santos sequence. Themaximum thickness is around 400feet in the Antelope Hills area. Itis conformably and unconforrnablyoverlain by the “Upper” Santosshale and underlain by and probablygrades into the “Lower” Santosshale. It is truncated by the base ofthe Saucesian unconformity in theBeer Nose area. To the south, in theAntelope Hills Field, it is truncatedby the base of the “Button bed” unconformity. It has small outcrops inthe Temblor Hills, but it is mainlysubsurface.

DIVISIONS:None.OIL AND GAs: North Antelope 15°

oil, Antelope Williams 17° oil, McDonald 25° oil, and North Belridge45° oil.

“LOWER” SANTOS SHALE MEMBERLOWER MIOCENE ZEMORRIANTYPE LOCALITY: Santos Creek,

Gester and Galloway (1933) andGilboe (1931). The term “Lower”Santos shale was mentioned byGoudkoff (1943). Santos informal,“Lower” Santos local usage.

40

CHARACTERISTICS AND LITHOLOGY:Dark brown to gray brown shaleand gray brown silt with interbeddedshale.

FAUNA AND AGE: Foraminiferscontained in the upper shales of the“Lower” Santos are representative ofKleinpell’s (1938) upper division ofthe Lower Miocene Zemorrian stage,the Uvigerinelkz sparsicostata zone.Some of the species reported byKleinpell in the Zemorra Creeksection are: Bulimina carnerosensis,Gyro idina s o I d a n i i, Saracenariaschencki, Siphogenerina mayi andUvigerinella sparsicosteta.

Uvigerina gallowayi, Uvigerinakernensis, Uvigerina “pseudoatwilli”and Pseudoglanclulina gallowayi arefound in .the lower shales of the“Lower” Santos. The foraminifersplace these lower shales in the lowerdivision of the Zemorrian stage, theUvigerina gallowayi zone.

STRATIGRAPHIC RELATIONSHIPS:The Lower Santos sequence has anerratic basal sand, the “Bloemer,”the “Lower” Santos shale and, finally, the massive Agua sand which,in places is truncated by an unconformity. The maximum thicknessof the “Lower” Santos shale isprobably 375 feet at N. E. MeKittrick. It is conformably overlain bythe Agua sand and underlain conformably and unconformably bythe “Phacoides sand.” In the vicinityof uplifts, it is unconformably over-lain by the “Upper” Santos shaleand by the “Button bed.” It outcropsin the Temblor Range, but it is overlapped northward by the “Upper”Santos shale.

DIVISIONS:

BLOEMER SAND named after theOhio Bloemer Lease, Section 36-27S/20E. It is a basal Lower Santossand found at North Belridge andelsewhere. There is a correlationdifficulty in that the Bloemer probably correlates with the thin “Phacoides” in the Antelope Hills area.Unfortunately, the type “Phacoides”may belong here rather than withthe “Phacoides” described subsequently.

OIL AND GAs: Bloemer sand atNorth Beiridge and possibly thethin “Phacoides” sands elsewhere.

“PHACOIDES SAND” MEMBERLOWER MIOCENE-LOWER

ZEMORRIANTYPE LOCALITY: Kleinpell (1938)

p. 107, Goudkoff (1943) p. 250,mentions that the “Phacoides” Reefis exposed in Salt Creek and inChico Martinez Creek. However, the

name “Phacoides” is now used fora sand that is probably underneaththis one. Local usage.

CHARACTERISTICS AND LITHOLOGY:Light gray sandy siltstones at thebase, grading to massive sand withthin hard gray lenses becomingcoarser and having glauconite at thetop.

FAUNA AND AGE: Molluscan assemblages containing Pecten (Chiamys)sespeensis, Pecten branneri, Bruclarkia (Agasoma) barkeriana, Lucina acutilineatus, Amantus mathew.soni, Clementia pertenuis and Os.trea sp. found in the Phacoides“reefs” are relatable to the molluscan “Turritella inezana” zone andplaced in the Zemorrian stage of theLower Miocene by Kleinpell (1938).The Phacoides stratigraphic relationship would further place the Phacoides in the lower division of theZemorrian stage.

In the calcareous and glauconiticPhacoides sand in the vicinity ofChico Martinez-Zemorra Creek area,the following microfossils werefound: Cibicicles /loridanus, Robulusinoratus, Uvigerinelict obesa impolita,Elphidium sp. and Sporbo andsponge spicules.

STRATIGRAPHIC RELATIONSHIPS:This is the pre-unconformity sand inthe Salt Creek sequence. The maximum thickness is in excess of 400feet. It is conformably and unconformably overlain by the “Lower”Santos shale and underlain and inter-fingers into the “Salt Creek shale.”It is unconformably truncated by theincompletely known base of theLower Santos unconformity.

DIvIsIoNs:

BELRIDGE “64” SAND is namedafter the Belridge #64 well in Section 27-27S/20E. The type Phacoidesmay correlate with Bloemer in thepreviously described unit.

OIL AND GAs: The principle areasof production are the North Bel.ridge and N. E. McKittrick-RailroadGap area.

“SALT CREEK SHALE” MEMBERLOWER MIOCENE-LOWER

ZEMORRIAN

TYPE LOCALITY: Mentioned byGoudkoff (1943) in the subsurface.Presumably named after Salt Creeksouthwest of the Cymric Field.Named by J. R. Williams (1936) inDiv. Oil & Gas. Calif. Oil FieldsVol. 21, No. 4 called the “SaltCreek”—shale between the Bloemerand Belridge “64” sand. Local usage.

CHARACTERISTICS AND LITHOLOGY:Greenish black to black sandy siltswith thin sands and an erratic basalsand. Also a massive brown shale.

FAUNA AND AGE: The microfossilassemblage contained in the SaltCreek shales have a high percentageof arenaceous foraminifers. Theforaminiferal assemblages are considered to be Lower Miocene, LowerZemorrian in age. Some of the foraminifers found in these shales are:Buliminella curta, Glandulina laeviga;a, Globigerina bulloides, Gyroidma so Id an ii, Plecto/rondiculariavaughani, ~Jyclammina incisa, Haplo.phragmoides translucens, Ammobaculites sp. and coarse Trochamminaspp.

STRATIGRAPHIC RELATIONSHIPS:This is the basil portion of the SaltCreek sequence consisting of a shaleand an erratic basal sand. Maximumthickness of the Salt Creek is probably 825 feet on the east flank ofthe Devil’s Den area. It is conformably overlain and grades into the“Phacoides sand,” and underlain bythe Tumey shale. It unconformablyoverlaps formations from the Tumeyto as old as the Eocene. It outcropsin the central portion of the TemblorRange.

DIVISIONS:GIBSON SAND is named after the

Union Gibson lease in Section 36-27S/20E. This name conflicts withthe Gibson sand of Upper Antelopeage in the Midway Sunset area.

OIL AND GAS: Very little production. Shows in the Gibson sand.Some production in the basal grit.

TUMEY FORMATIONTUMEY SHALE MEMBEROLIGOCENE-REFUGIAN

TYPE LOCALITY: Tumey Gulch,S/2 Section 16-16S/13E, north ofCoalinga, by Atwill (1935) pp.1192-1204. A more complete sectionis found just south of the type areain the Arroyo Ciervo, 16S/13E~Cushman and Simonson (1944).Informal. The Lexicon (1966) treatsit as a member of the KreyenhagenFormation.

CHARACTERISTICS AND LITHOLOGY:Lithofacies in the south end of thevalley (Tecuya) are non-marinebeds consisting of red and greensilts, coarse granular sandstone,massive conglomerates. In the Devil’sDen district (Wagonwheel formation) it consists of fossiliferoussandstone with an overlying siltstone.Northward to Tumey Gulch it consists of thick shale with lenticularsands.

FAUNA AND AGE: Characteristicforaminifers of the Tumey, exclusiveof the Leda and Transition zones ofCushman and Simonson (1944),are: Plecto/rondicularia packardiand var. multilineata, Plecto/rondicularia garzaensis, Bolivina jacksonensis, Cibicides hodgei, Uvigerinagarzaensis, Uvigerina atwilli, Uvigerina cocoaensis, Bulimina cf. schwageri and Guttulina irregularis.These foraminifers are indicative ofthe Oligocene Refugian stage.

STRATIGRAPHIC RELATIONSHIPS:This is the upper part of the Oligocene sequence. The maximum thickness of 1600 feet extends from theeast flank of Devil’s Den north tothe type section. Southward it is 500feet or less. It is conformably andunconformably overlain by the “SaltCreek shale” and conformably underlain by the “Oceanic sand” andthe Kreyenhagen shale. It is unconformably truncated by the base ofthe Miocene unconformity and thebase of the Saucesian unconformity.The Tumey outcrops at the typesection, and in the Devil’s Den area,and at the south end of the valley.

DIVISIONS:

WAGONWHEEL FORMATION is usedin the Devil’s Den district as theequivalent to the Tumey shale.Named by H. R. Johnston (1909),Smith (1956). Although this namepredates the Tumey and is closerto the oilfields, it is little used.

TECUYA FORMATION, Stock. Univ.Calif. Geol. Dept. Bull. Vol. 12(1920) pp. 267-276. Named afterTecuya Creek near the Grapevine.

OIL AND GAS: Heavy oil occursin the fractured shales of the Tumeyin the Welcome Valley Field. Somelenticular sands on the east flank ofDevil’s Den also have small accumulations.

“OCEANIS SAND” MEMBEROLIGOCENE

TYPE LOCALITY: The “Oceanicsand” (subsurface only) was namedafter the Oceanic lease in the CymricWelport area, Section 22-29S/21E.Local usage.

CHARACTERISTICS AND LITHOLOGY:Light brown, fine to medium grainedsand with some kaolin.

FAUNA AND AGE: Only molluscanfragments have been recorded fromthe Oceanic sands. Stratigraphicposition (lying between the RefugianTumey shales and uppermost Nanzian age Kreyenhagen shales) placesthe Oceanic sands as probable LowerRefugian Oligocene in age.

STRATIGRAPHIC RELATIONSHIPS:The “Oceanic sand” is the basalportion of the Oligocene sequence.It extends from the Belgian Anti.dine-N. E. McKittrick area to theNorth Belridge - Blackwells Cornerarea. The maximum thickness isprobably less than 200 feet. It isconformably ovenlain by and gradesinto the Tumey shale; and it is conformably and unconformably underlain by the Kreyenhagen shale. Ithas no outcrops because it is alwaystruncated by the base of the Mioceneand other unconformities beforereaching the surface.

DIVISIONS:None.

OIL AND GAS: 32-36° oil is produced from the northeast flank ofBelgian Anticline, NW end of N. E.McKittrick, McKittrick Front, Cymnc Welport and Sheep Springs areas,and the north end of North Beiridge.Also a small amount of 20° oil wasproduced at the Bacon Hills area ofthe McDonald Field.

KREYENHAGENFORMATION

EOCENETYPE LOCALITY: It was named by

F. M. Anderson (1905) p. 163, fromthe Kneyenhagen wells located inSections 32, 33-22S/16E, south ofCoalinga. Formal. In local usage theKreyenhagen shale is used also as amember of the Kreyenhagen Formation overlying the Point of Rocks.

CHARACTERISTICS AND LITHOLOGY:Dark brown to medium gray fissileshale with fish remains, spongespicules and radiolania. Typicallylavender brown siliceous splinterysiltstone and shale with some sandsand limestones.

FAUNA AND AGE: “Restricted”Kreyenhagen (drawn at the Refugian-Narizian contact) encompassesthe Bulimina corrugata and Amphimorphina jenkensi zones of the Upper Eocene Narizian stage of Mallory(1959). Some of the foraminifersreported from the “restricted” Kreyenhagen shale are: Amphimorphinajenkensi, Bulimina corrugata, Anomalina garzaensis, Asterigerina crassi/ormis, B a ii m i n a microcostata,E p o n i d e s umbonata, Planulariamarkleyana, Gy-roidina soldanii octocamerata, Robulus weichi, Uvigerinagarzaensis and Uvigerina churchi.

STRATIGRAPHIC RELATIONSHIPS:It is the upper shale member of theKreyenhagen sequence, the maxi

II

41

mum thickness of which is about1500 feet. It is conformably andunconformably overlain by theTumey and the “Oceanic,” and underlain and grades into the Pointof Rocks sandstone. It is truncatedon top by the base of the Miocene,base of the Saucesian, base of theUpper and Middle Miocene, andbase of the Tulare unconformities.The main outcrops of the Kreyenhagen shale are north of the Pyramid Hills Field.

DIvIsIoNs:

WELCOME MEMBER of the Kreyenhagen Formation was named by VanCouvering and Allen (1943) p. 496.This is a tongue of the Kreyenhagenshale where it overlies the Point ofRocks sandstone in the Devil’s Dendistrict. Although it is little used,according to the Code (1961) andLexicon (1966) it should be usedin preference to Kreyenhagen shalemember.

REED CANYON SILT. Probablyequivalent to the Kreyenhagen atthe south end of the valley.

OIL AND GAS: Small amounts ofoil were produced from fracturedshale in the Middle Dome KettlemanHills.

POINT OF ROCKS SANDSTONEMEMBEREOCENE

TYPE LOCALITY: The Point ofRocks was originally designated asa unit of the Tejon Formation, butis here discussed under the Kreyenhagen Formation. Named by Reedand Hollister (1936) p. 1566, on acolumnar section from the Point ofRocks northwest of the WelcomeValley Field, Section 2-26S/18E.Informal.

CHARACTERISTICS AND LITHLOLGY:Massive, coarse to medium grainedarkosic sandstone with “cannonball”concretions.

FAUNA AND AGE: The Point ofRocks sandstones encompass most, ifnot all, of the Upper Eocene Bulimina microcostata zone of the LowerNarizian and extend through theA mphimorphina calijornica zone andat least down into the Vaginulinopsismexicana zone; both of these latterzones are of Middle Eocene ageand belong to Mallory’s (1959)Ulatisian stage. Shale and silt inter-beds in the Point of Rocks sandscontain such forms as: Uvigerinachurchi, Bulimina corrugata, Dorothia principensis, Gyroidina orbicularis planata and Cibicides “pygmaea.”

42

STRATIGRAPHIC RELATIONSHIPS:This is the middle sand of the Kreyenhagen sequence. The maximumthickness is in excess of 5000 feet.It is conformably overlain andgrades into the Kreyenhagen shaleand conformably underlain andgrades into the Canoas shale. Itoutcrops in the Temblor Rangefrom the Cymric Field northward.

DIvISIoNS:

None, but it is divided into several separate sands at Belgian Antidine and Pyramid Hills.

OIL AND GAS: Belgian Anticline,Cymric Welport (30°), AntelopeHills (17°), Shale Point South,Devil’s Den Alferitz (37°) andPyramid Hills Field (16-17°). Theheavy oils are associated with unconformities.

CANOAS SILTSTONE MEMBEREOCENE

TYPE SECTION: Named after Canoas Creek about 20 miles south ofCoalinga. Mentioned in Calif. Div.of Mines. Bull. 118 by Clark, p.187, and Chambers, p. 487; and byCushman and Siegfus (1942). Typelocality is Garza Creek, KingsCounty. Formal. Basal member ofthe Kreyenhagen.

CHARACTERISTICS AND LITHOLOGY:Gray claystone locally silty withsome thin glauconitic sandstone. Thebasal lenticular Mabury sand is amassive, medium to coarse grainedto pebbly sand with glauconite nearthe base.

FAUNA AND AGE: The siltstones inthe basal Kreyenhagen in the CoalMine Canyon and Cantua Creekarea develop locally into a unit referred to as the Canoas siltstone.The foraminifers contained in thesesiltstones are Middle Eocene in ageand are placed by Mallory (1959)in the Amphimorphina californicazone of the Upper Ulatisian. Someof the foraminifers characteristic ofthe Canos are: Vaginulinopsis asperuliformis, Martinotiella cf. petrosa,Bifarina nuttalli, Pleurostomella nuttalli and Anomalina dorri aragonensis.

STRATIGRAPHIC RELATIONSHIPS:This is the lower shale and basalsand if the Kreyenhagen sequence.It is conformably overlain andgrades into the Point of Rocks sand.It is underlain conformably andunconformably by the Domengineand older beds. It outcrops west ofthe Chico Martinez area, at Devil’sDen, and further north.

DIVISIONS:

The correlation and the possibleequivalents need further study be.cause of the confusion in the literature. Tentatively, these units areconsidered as part of the Canoashorizon.

“MUD PIT SHALE” is an equivalentname for the Canoas Siltstone nowno longer used.

GREDAL. Van Couvering and Allen (1943) Devil’s Den district.Equivalent to the Canoas silt. D.O.G.Sum. Oper., Vol. 43, No. 1 (1957).Variegated, green-red claystone containing occasional sandstone bedsand considerable glauconite. Mallory(1959) refers to the Gredal as amember of the Lodo formation.

MABURY SAND is the basal sandmember of the Canoas. There arealso other sands in the Canoas.Van Couvering and Allen (1943)pp. 496-500. Named after the Ma-bury Hills where it outcrops inSections 10, 11-26S/18E. Coarsetan sandstone with black chert pebbles, containing Spiroglyphus tejonensis.

OIL AND GAS: Gas occurs in theMabury sand at Shale Point, ShaleFlat and Bolton areas in 27S/19E.Oil occurs in lenticular sands in theNorris area and the Orchard areaof 24S/18E. The traps are near thepinch outs of the sands.

BIBLOGRAPHY

Listed According to Date(Editor’s note: The Bibliography is

presented in this form to show thechronology of the stratigraphic nomenclature.)

GENERALWilmarth (1938) USGS Bull. 896, 2

parts, 2396 Pp. “Lexicon of Geologicnames of the United States.” (pre1936).

Kleinpell (1938) Miocene Stratigrapliy ofCalifornia AAPG.

Sloss, Krumbein, & Dapples (1949) GSAMemoir 39, pp. 110-121. “Sequences.”

Mallory (1959) Lower Tertiary Biostratigraphy of the California Coast RangesAAPG.

Stratigraphic Code (1961) APPG Bull.(May 1961) pp. 645-665.

Keroher (1966) USGS Bull. 1200, 3 parts,4341 pp. “Lexicon of Geologic Namesof the United States 1936-1960.”

SPECIFIC STRATIGRAPHIC UNITSF. M. Anderson (1905) Proc. Calif. Acad.

Sci. 3rd Series Geol. Vol. 2, No. 2.Tulare, San Joaquin, Etchegoin, “Button bed,” Temblor, and Kreyenhagen.

Arnold & Anderson (1908) USGS Bull.357, Jacalitos.

______ (1909) “Paleontology of the

Coalinga District.” USGS Bull. 396.Johnson (1909) Science, new series, Vol.

30, pp. 63-64. Wagonwheel (Tumeyequiv.).

J

May & Gilboe (1931) Stanford Univ.unpubi. manuscript. Gould, Media, Carneros, Santos, and Phacoides reef.

Cunningham & Barbat (1932) AAPG Bull.(April 1932) pp. 417-421. Gould, Media,Carneros.

Barbat & Johnson (1933) Pan Amer. Geol.Vol. 59, No. 3, p. 239. Reef Ridge.

Gester & Galloway (1933) AAPG Bull.(Oct. 1933) pp. 1174-1176. Santos.

Barbat & Galloway (1934) AAPG Bull.(April 1934) pp. 476-499. San Joaquin,Etchegoin (restricted).

Clark & Clark (1935) Abstract AAPGBull. (Jan. 1935) p. 137. Agua.

Atwill (1935) AAPG Bull. (Aug. 1935)pp. 1192-1204. Tumey.

Reed & Hollister (1936) AAPG Bull.(Dec. 1936) p. 1566. Point of Rocks.

Cushman & Goudkoff (1938) Contributionsfrom the Cushman Lab. (March 1938).McDonald (Pulv. zone).

Hoots (1938) AAPG Bull. (June 1938)pp. 701-718. Stevens.

Siegfus (1939) AAPG Bull. (Jan. 1939)

pp. 24-44. Reef Ridge (restricted).Bailey (1939) D.O.G. Sum, of Operations

No. 3, pp. 66-71. “Wasco Field.” Devil-water.

Woodring, Stewart & Richards (1940)USGS Prof. Paper 195. Detail on Tulare, San Joaquin, Etchegoin, Montereymembers, etc.

Noble (1940) AAPG Bull. (July 1940)pp. 1330-1333. “Rio Bravo Field.” Antelope.

Cushman & Siegfus (1942) San DiegoSoc. Nat. History, Vol. 9, No. 34.Canoas.

Simonson & Krueger (1942) AAPG Bull.(Oct. 1942). Detail on Antelope, McDonald, etc.

Van Couvering & Allen (1943) Calif. Div.Mines Bull. 118, pp. 496.501. Mabury,Gredal, Welcome, Alferitz.

Goudkoff (1943) Calif. Div. Mines Bull.118, pp. 247-252. Divided Santos intoUpper Santos (Saucesian) and LowerSantos (Zemorrian), Phacoides, SaltCreek.

Clark (1943) Calif. Div. Mines Bull. 118,p. 189. Canoas.

Cushman & Simonson (1944) Jour. Paleon.(March 1944) pp. 186-203. Tumeymicrofauna.

Heikkila & MacLeod (1951) Calif. Div.Mines Special Report #6. Agua, etc.,detailed.

Frick & Kues (1954) AAPG Bull. (Nov.1954) pp. 2357.2371. Corcoran.

Smith (1956) Univ. Calif. Publ. Geol.Sciences, Vol. 32, No. 2, pp. 65-126.Wagonwheel (Tumey) microfauna.San Joaquin Geol. Soc. Guidebook(1959). “Chico Martinez Creek.” ChicoMartinez, Miocene paleo.

STRATIGRAPHY OF THE OILFIELDSCalifornia Division of Mines Bulletin 118

(1943).AAPG, SEPM, SEG Annual Meeting

Guidebook, Los Angeles, California(1952).

California Oil Fields, Division of Oil andGas Summary of Operations (semiannually).

Production on the west side ofthe southern San Joaquin Valley isfrom shaly sands. While the degreeof shaliness varies, truly clean sandsare rarely encountered. Furthercharacterization of the producingformations requires classification bydepth. In the deeper producing sandsthe formation waters are brackish tosalty; in the shallow zones the watersare fresh. Porosities are generallyhigher in the shallower unconsolidated sands. Log evaluation of theshallow sands, already made difficultby shaliness, fresh water, and lackof compaction, is further complicatedby the common occurrence of low.gravity, high-viscosity crude oils.The special interpretation methodsfor these shallow zones will be covered following discussion of themore common methods used for thedeeper sands.

SOME SOLUTIONS TO LOGGING PROBLEMS ON

THE WEST SIDE OF CALIFORNIA’S

SAN JOAQUIN VALLEY’

ARMOUR KANE2

LOG EVALUATION OF THEDEEPER HORIZONS

The minimum logging programfor the deeper sands consists ofan Induction-Electrical Survey andeither a Sonic Log or a Formation

‘Manuscript submitted Feb. 1968.2Schlumberger Well Services,

Bakersfield, California.

Density Log. The Induction-Electrical Survey (IES) provides correlation control for subsurface mappingand structural studies. In addition,the resistivity values from the IESare used with porosity data to findand evaluate oil- and gas-bearingzones.

While either sonic or density logsprovide porosity control to augmentthe IES, the choice of which to use

depends on the primary problemto be solved. The IES-Sonic combination provides the most reliableidentification of hydrocarbon - bearing shaly sands. The pessimisticeffect of shaliness on resistivitymeasurements is offset by an optimistic effect on sonic-derived porosities. However, if accuracy ofporosity measurements is the moreimportant, the better combination