__....,. ./ 

) 

DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, 'Secretary 

. RETURN TO lAND DEPARTMENT 

GI:.NERAL rCT:tOLEUM CORPORATION 

SAN FRANCISCO, CALIFORNIA 

NO •.••.•• •••••• • • • • •·• · • • • • • • • • • • 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Direct9r 

PROFESSIONAL PAPER 116 

THE SUNSET-MIDWAY OIL FIELD 

CALIJ.1~0RNIA 

PART I. GEOLOGY AND OIL RESOURCES 

BY 

WASHINGTON 

GOVERNMENT PRINTING OFFIOE 

1920 

.\ 
• 

DEPARTMENT OF THE INTERIOR 

FRANKLIN K. LANE, Secretary 

UNITED STATES GEOLOGICAL SURVEY 

GEORGE OTIS SMITH, Director 

Professional Paper 116_, 

THE SUNSET~MIDWA.Y OIL FIELD· 

CALIFORNIA 

RETURN TO LANO DEPARTMENT 

Gt.NERAL rrr:~;;LEU~1 C02~0RATION. 

· SAN FRANCISCO, CALIFORNIA 

NO.~ ..................••••.••.... 

' ' PART I. GEOLOGY AND OIL RES~§ lAND DEPARTMENT 

~ENERAL PETROLEUM CORPORATION 

BY SAN FRANCISCO, CALlFORNlA 

R. W.· PACK 

,No ..••••••••••••••••• ' ••• 

I

. . ....... . 

WASHINGTON 

GOVERNMENT PRI.NTING OFFICE 

192.0 

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CONTENTS. 

Summary of results ....................... · .......... : ................................... · .................. . 

Introduction .................................. · ................ , ........................................ . 

Purpose of the report ............................................................... ~ · ... 1

: ••••••••••••• 

Location of the fie1d .................................................... : ........... · ..... ." ............. . 

Relief .......... : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... ~ .. · ............ . 

Climate and vegetation .............................................................................. . 

Field work and acknowledgments ...................................................................... · 

Bibliography ....................................... _ ....................................... _ ...... . 

Stratigraphy ................................................. · .......... '.: ...... __ .... _ ..... _. . ....... . 

General character and distribution of formations ...................................................... . 

Pre-'l'ertiary rocks ................................................................................... . 

Crystalline rocks.~ ................................................................................ . 

General character ........................................................................... . 

Econonric in1portance ................................... · ...•.................................. 

I-'ate 1\{esozoic rocks ............................................................................. . 

'l'ertiary system .......••............................................................................. 

Tejon formation (Eocene) ......... , .............................................................. . 

General character and stratigraplric relations ................................................. . 

Distribution and lithology .......... ~ ........................................................ . 

Age and correlation ........................................................ ~-·-- ............. . 

Importance with relation to petroleum ........................ · ............................... . 

Oligocene and Miocene rocks .................................................... : . ............... . 

Nomenclature .................................•.......................... , ................. . 

Relation of the formations .. ." ..................... · ...................... '................ . 

Vaqueros formation ......................... · ............................................. . 

1\fonterey group ......... · ................................................................. . 

l\:£aricopa shale ......................•.......... ~ .......................................... . 

Santa :Margarita formation .•............................................... · .... : ......... . 

Vaqueros formation (lower Miocene) ......•.................................................... 

General character and stratigraplric relations ............................................. . 

Lithology and distribution ................... : . ........................................... . 

Area east of Santiago Creek .......................................................... . 

Area west of Santiago Creek .. ~ ........... ~ .................... , ..................... . 

Area along Pioneer anticline ........•................... ~ ................... ~ ....... . 

Area about Sunset Canyon ........................................................... . 

Importance with relation to petroleum .................................................. · .. 

Maricopa shale (middle Miocene) ........ · ..................................................... . 

General character and stratigraphic relations ............................................. . 

Conditions governi~g deposition ......................................................... . 

Di::Jtribution ................. · ................ · .............................. ., ........... . 

Lithology ............................................................... : ............. . 

General character.~ ................................................................. . 

Lower division ................................................... · ................... . 

Area in the SaR Enrigdio Mountains west of San Enrigdio Creek .................... . 

Area in the Temblor Range ... -...................... · ............................ . 

Area east of San Enrigdio Creek ................................................. . 

Upper division .......................... · ............................................ , 

Area north of Crocker Springs ................................................... . 

Area in the Midway district ............... · ............. ~ ....................... . 

Area in the Pleito Hills ........................ : . ........... · .................... . 

Importance with relation to petroleum ................................................ · ... . 

Santa Margarita formation (nriddle Miocene) ................................................. . 

General character and stratigraphic relations ............................................. . 

Lithology .. ~- ......................................................................... . 

Importance with· relation to petroleum ............................................... ~ ... . 

3 

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4 CONTENTS. 

Stratigraphy-Continued. 

Tertiary system-Continued. 

Oligocene and Miocene rocks-Continued. 

McKittrick group (upper Miocene, Pliocene, and Pleistocene?) ...... : ......................... . 

Definition and general features ................................... · ....................... . 

Importance with relation to petroleum .................................................. .. 

Etchegoin formation ......... _ ............................ : . ............................ . 

' Stratigraphic relations ........... · ........................................ , ............ . 

Distribution and lithology .................... ~ ...................................... . 

Outcrops in the San Emigdio Mountains ..................... : ........................ . 

Outcrops in the Temblor Range .. · ................................................. .. 

Area where the Etchegoin is not exposed beneath the productive oil field .............. . 

Paso Robles ("Tulare")formation .......................................... · ............ .. 

General character and stratigraphic relations ................................... : ..... . 

Thickness ..... · .................................................................... . 

Quaternary syste!~~~~~~~~ -~~~~~~~~~ ·_· .-~ ~ ~ ·. ·_· ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ -~ ~ ~ ~ ~ ~ ~ ·~: ~ ~ ~ ~ ~ ~ -~ ~ ~ ~ -~: : : ~ : ~ : ~ ~ ~ ~ :: ~: ~: ~: ·.: 

Tertiary'i;:~~: ~:~~:~~- ~~~- ~~l~~-~~--.· ~ ~- ~ ~ ·. · ... · _-:: : ~ :: ~ ~ :: : ~ ~: : : ~: : : :: : : :: : : : : : : : : : _: : : : : :: : : : : :: : : : : :: : : : : 

Distribution .............. · .................... _. ..•. ~ ................................ ·. _. .............. . 

· Stratigraphic relations ..................... · .... : ..................................................... . 

, Lithologic character ......... ~ ....................... : . ................................................ . 

Structure .......... : . ........ _ ............. : .......................... _ ........................ · ..... · ..... . 

· Geologic relations to near-by regions ................................................................. . 

General structural features of the Sunset-Midway district ............................................. . 

Temblor Range and outlying foothill ranges ....... ; .............................................. . 

General featlrres ........ ~ ........................... _, __ .................................... . 

Structural details in the foothills ........... : .............. · .. · ................................ . 

Elk Hills ................................................. · .............................. . 

Buena Vista Hills ....................................................................... . 

Foothills west of Midway Vailey ................. __ · ..................................... . 

San Emigdio Mountains ......... · ............. · .................................................. . 

General features ....................•......... _· ............................................ . 

Details of structure ..................... _- .................................................... . 

Area west of Santiago Creek ............................................................. . 

Area east of Santiago Creek .................. : ........................................... . 

Petroleum ......................................................... · ........... _ ...... _ ................. . 

History of development .................................. _. ............. ' ............................. . 

Production ...................................... · ......................................... _ ........ . 

Pipe lines· ................ ~ .......................................................................... . 

Water supply ............ · .................................. ~ .... _ ....................... _ ........... . 

Withdrawals ............ ~ .. ~,_._ ........................... ~ ......................................... . 

Origin of the petroleum ............................................................................. . 

Factors influencing accumulation of the oil. ......................................................... . 

Larger geologic features determining the location: of the oil field. . . . . . . . . . . . . . . . . .................. . 

Lesser geologic features controlling the· position of the oil Within the field .......................... . 

Effect of the smaller structural features ......... ·.: ..................................... : ..... . 

Unconformities ............................................... · ............. : ... ~ ........ . 

Secohdary anticlines and synclines .. ~ .............. ~ , ............. : . .................. .. 

Effects of lithology .............................. ~ ........................................... . 

Effect of the chemical and physical character. of the oil ..................................... · .. . 

Pressure under which oil exists in the pools ............................................... : ......... .. 

Explanation of the '' gilsher sands" ..............................• , .................................. . 

Character of the oil ......... ~ .......... · ..................................... , ....................... . 

Effect of mineralized waters on the o!I. .......................... .-..... · ............................... . 

Details of the productive field .................................... : ~ . :. : .................. · ............. .. 

Doheny Pacific-Carnegie area ....................................................................... . 

Engineers-Coalinga Monterey area .................................................................... . 

Globe-Bear Creek area ........ ~ ....... : ............ · ................................................. . 

Traffic-Starlight area ........... : .......................... · ......................................... . 

Brookshire-Gem area ...... ·.- ..... ·.· .......... : ............... · .. · ...................................... . 

_El Camino-PioneerMidwayarea ................................................ , .................. .. 

State-American Oilfields area .................... ~ ................................................. .. 

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CONTENTS. 

Details of the productive field-Continued. 

1\{ocal-Hawaiian area ............................................................................... . 

Pioneer Midway-Midway Consoli~ated area: ................ ~ ......................................... . 

1\{ammoth-St. La,vrence area ....................................................... _· ............... . 

California Counties-Con tin en tal area ......... -........ _· ................... ~ .............. ·: . ........... . 

Stratton Water-Lockwood area ........ , ............................... ~ .............................. . 

J.Joc k\vood-Talara area. ............................. · .. ~ .. · ........... : ................................ . 

Dunlop-Section Twenty-five area .. ; .................. ~ ............................................. .. 

1\.1-ea east of Twenty-five Hill ....................................................................... . 

Sage-Lakevie'v area .............. : .................................................................. . 

E~::E~~:: :::::::::::::::::::::::::::::::::::::: :~:: :::::::::::::::::::::::: :~:: :::::::::::: 

Rudisill-Barnodon area ................... · ......................................................... · .. . 

Calidon-Record area .............................................................. .' .... · ...... · ....... . 

l\{cNee-l\1cLeod area .......................................... : ........ · .............................. . 

South half of Buena Vista Hills. . . . . . . . . . . . . . . . .......... · .......................................... . 

Southeastern part of T. 32 S., R. 24 E., and outskirts of Maricopa Flat ............ : ............ : ....... . 

Areas adjacent to the Sunset-Midway field ............. · ....................................... ~ .. ~ ...... .. 

Elk Hills .. · ............ : ...... ·_ ..................................... ·· ............................... : 

Wheeler Ridge .............................. ~ .............................................. ~ ........ . 

Foothills of the San Emigdio Mountains .......................................... : ................... . 

Higher parts of the Temblor Range .................................................................. . 

Elevations of wells in north end of Midway field ................... · ............... _·_ ....... ~ ............. . 

Index ................................................ __ ..... __ ..... _ ... __ .. __ .. _.-.•... _. _____ . __________ _ 

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ILLUSTRATIONS. 

Page. · 

PLATE I. Topographic map of the Sunset-Midway oil field, Kern County, CaL ...••..••....••••••... ~ In pocket. 

II. Geologic map of the Sunset-Midway oil field, Kerp. County, CaL ........................... In pocket. 

III. Map of the Sunset-Midway oil field, showing geologic structure and the position of the tops of the 

productive oil zones ............. · ....................................................... In pocket. 

IV. A, Midway oil field in 1907; B, Sunset oil field in 1901............................. .. . . . . . . .. .. .. 16 

V. Foothills formed of Tertiary rocks on west side of Salt Creek. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

VI. A, Boulder of granitic ro·ck in San Joaquin Valley; B, Granite boulder in upper part of Maricopa shale 

west of Fellows; C, WestendofSanEmigdio Mountains . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 19 

VII. Basal part of Tejon formation on Los Lo bos Creek in foothills of San Emigdio Mountains: A, General 

· · view; B, Detail ............................................................ ~. . . . . . . . . . . . . . . 24 

VIII. Devils Kitchen, San Emigdio Canyon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

IX. A, Outer foothills east of San Emigdio Creek; B, Foothills onno.rthslopeofSanEmigdioMow1tains. 32 

X. A, Outcrop of diatomaceous Maricopa shale in Pleito Hills; B, Unconformity between diatomaceous 

Maricopa shale and clay shale of Etchegoin formation in San Emigdio region.. . . . . . . . . . . . . . . . . . . 33 

XI. A,. Brea in arroyo near Muddy Creek, in San Emigdio region; B, Bed filled with fossils at base of 

. Etchegoin formation near Muddy Creek..................................................... 46 

XII. A, Terraces near mouth of Santiago Creek; B, Terraces on Los Lobos Creek........................ 50 

XIII. A, Old Jewett & Blodgett asphalt refinery south of Pioneer; B, Terrace gravels along San Emigdio 

· Creek about 2 miles from edge of San Joaquin Valley ......•....... .-.......................... 51 

XIV. Unconformity between late Tertiary gravels and tilted Pleistocene or Recent gravels ·in San 

Emigdio region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 

XV. Relief map of California .......... ·_ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 

XVI. Geologic section along east-west center line of sec. 14, T. 31 S.,. R. 22 E ...................... •In pocket. 

XVII. Geologic section along north-south cente"r line of sec. 23, T. 31 S., R. 22 E ................... In pocket. 

XVIII. A, Geologic section along west line of the S.! SE. t sec. 25, T. 31 S., R. 22 E.; B, Geologic section 

. along south line of theSE. t sec. 25, T. 31 S., R. 22 E., and the SW. t sec. 301 T. 31 S., R. 23 E. In pocket. 

XIX. Geologic section along east line of Pacific Crude property, in theSE. tsec. 32, T. 318., R. 23 E. In pocket. 

XX. Geologic section along.south line of the NE. t sec. 32, T. 31 S., R. 23 E. ..................... In pocket. 

XXI. Geologic section along east-west center line of the S.! sec. 32,_ T. 31 S., R. 23 E ............. In pocket. 

XXII. Geologicsection.alongwestline of theSE. i sec. 5, T. 32 S., R. 23 E ......................... In pocket. 

XXIII. Geologic section along northeastward-trending line from the NE. t sec. 4, T. 32 S., R. 23 E., to the 

SW. t.sec. 22, T. 31 S., R. 23 E .........................••............................. In pocket. · 

XXIV .. Geologic section along south line of sees. 34 and 35, T. 31 S., R. 23 E ....................... In pocket. 

XXV. Geologic section along northward-trending line in the NE. t sec. 2, T. 32 S., ·R. 23 E .......... In pocket. 

XXVI. Geologic"section along north line of sec.l6, T .. 32 S., R. 24 E ................................ In pocket. 

XXVII. Geologic section along west line of the NW. t sec. 6, T.ll N., R. 23 W., and the SW. tsec. 31, T. 12 

N., R. 23 W ................. ~ . . . . . . . . . . . . . . . . . . . . . . • . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . In pocket, 

XXVIII. Geologic section along south line of.secs. 31 and 32, T.12 N., R. 23 W ....................... In pocket. 

XXIX. Geologic section along northeastward-trending line tlllough the SW. t sec. 32, T.l2 N., R. 23 W. In pocket. 

XXX. Geologic section along west line of sec. 32, T. 12 N., R. 23 W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . In pocket. 

XXXI. Geologic section along southeastward-trending line from the center of sec. 32, T, 12 N., R. 23 W., 

to the center of sec. 4, T. 11 N., R. 23 W ................................ : . . . . . . . . . . . • . . . In pocket. 

XXXII. A, Crude derrick over a well drilled in the nineties; B, Derrick and gas trap in Maricopa Flat.... 64 

XXXIII. A, Sunset oil :field in October, 1908; B, Maricopa Flat, Sunset oil field, in 1914. . . . . . . . . . . . . . . . . . . 64 

XXXIV: Curves shoWing production of Sunset-Midway field ........ :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 

XXXV. Map showing petroleum withdrawals and naval petroleum reserves in area covered by geologic map 

(Pl. II) ........................ :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 

XXXVI. Sketch map showing approximate position of the upper surface of the bottom water sand in the 

southeastern part ofT. 31 S., R. 22·E....... .. . . . . . .. .. .. .. .. .. . . . . .. .. .. .. .. .. .. .. . . .. .. . . . . . 92 

XXXVII. Stereogram showing structure of oil sands in sec. 36, T .. 31 S., R. 22 E............................ 104 

XXXVIII. Map of north end of Twenty-five Rill showing sketched contours on upper surface of bottom water 

sands and contours on J. M. & S. sand.~ .... _. ...................... ." ................... ·.. . . . . 128 

'XXXIX. South end of TwenW-five Hill, Midway field................................................... 128 

6 
ILLUSTRATIONS. 7 

1 ' ' PLATE XL. A, Sump in foothills filled with oil from Miocene No. 1 well in 1914; B, The same sump filled with 

Page. 

oil from Lakeview No.1 gusher, October, 1910 ... __ .............. __ .. _ : . . ___ ... _. _ ... .. . .. ... 129 

XLI. A, Flowing well being brought in, Sunset oil field; B, Lakeview No. 2 gusher, May, 1914; c,· Lake 

· view No. 1 gusher, October 2, 1910. _. ____ .. · ____ .... _ ... _ ....... __ ... _ ....... ____ ........ _.... 138 

XLII. A, Well No.1 of Lakeview Oil Co. No. 2; B, Southeast end of plunging fold in Buena Vista Hills._ 139. 

XLIII. Map showing structure of principai oil and water sands in Maricopa Flat .. _ .. ____ ... ___ . . . In pocket 

XLIV. Map of old Sunset oil fiel<l, in T. 11 N. R. 23 W., showing position of oil sands._. __ .... ____ .. ____ 146 

. XLV. A, B, Casing corroded by water in the 11idway oil field; C, Sand made by well in the Sunset oil 

field ... _ ..... _ ....... _ ~ ........... _ ............. _: ....................... ____ ... ___ ..... _ . 160 

FIGURE 1. Index map of a part of California showing oil fields described in published reports.----.------.-.- 16 

2. Generalized columnar section of the rocks in the Sunset-Midway oil field and in the north flank oi' 

·the San Emigdio Mountains. __ ._. ___ .... _._._ .................... _ .. _ ..... _. -.- _ .. ___ ....... . 

3. Section of Vaqueros formation below the Tertiary volcanic rocks as exposed on divide between Salt 

and. Pleito creeks ............................................ .' ... _ ........ _ ............ _ .. . 

4. Section of rocks exposed on Muddy Creek .... _ .......................... ~._ .................. . 

5. Sketch map of part' of California showing position of· chief anticlines along the west border of s·an 

Joaquin Valley ......... ~ ........ _ ... _ .................... _._._ ................. _ ....... _ .. 

6. Sketch map of Sunset-Midway oil field showing position with relation to structure of wells.of high 

initial output _______ ..................... _ ... __ .. _ . _ .. _____ . _ . ___ ..... _ ... __ ... _ ... __ : . _ .. . 

7. Curves showing relation of viscosity to temperature in several crude oils __ . _ ... _ .... _ ... _ .... __ . 

8. Geologic cross section through Midway field along line R-R', Plate III. _________ ... __ .. __ .. _ .... . 

9. Diagram explaining method of constructing stereogram in Plate XXXVII. ___ .... _ ..... __ ._ .. __ . 

10. Diagram explaining method of constructing stereogram in Plate XXXVII. _ ...... _ .............. . 

11. Diagram explaining method of constructing stereogram in Plate XXXVII .. ____ ..... ____ ... __ .. . 

12. Diagram showing relation of water sands in sec. 32, T. 31 S., R. 23 E., to those in the northeastern 

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part of sec. 36, T. 31 S., R. 23 E _ .. ___ .-. _. _. ________ -'·· ........ _ ... _. __ ............ _....... 108 

13. Diagram showing relation of productive oil zones in the vicinity of Fellows ..... ___ ... _ .. _ .. _.... 115 

14. Diagram showing possible explanation·for occurrence' of water in the B zone in the northwestern 

part of sec. 15, T. 32 S. ,· R. 23 E ________ - _____________ ... _ .· ... _. __ .: ___ ... _ ... ___ . __ . _ . __ ... 126 

15. Sketch map showing approximate position of the top· of the Maricopa shale in the western part of 

the Sunset field ... · ....... ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . 138 

RETtmN TO lAND OEPARTMENT 

Gf.:NCRf.,L rCT:":C.LEJ.\1 CO~PORtUION 

~AN FRANCISCO, CALJFOf~NIA 

NO .......•• ~ ••••••••••••••••••••• 

SUMMA~Y oF· RESULTS. 

Location.-The Sunset-Midway oil field, in marine waters, but a conside~able part of even· 

Kern County, Calif., lies at the south end of San the older Tertiary material was laid down on 

Joaquin Valley and embraces the eastern foot- the surface of the land or in fresh-water lakes. 

hills of the Coast Ranges and the northern The youngest marine sedimentary beds are of 

foothills of the Snn Emigdio :Mountains, which late Miocene or Pliocene age, the more recent 

connect the Coast Ranges with the Sierra formations being composed wholly of terrestrial 

Nevada. The region is semiarid, and, a.s most or lacustrine beds that were deposited under 

of it is va~ueless for agriculture, it is inhabited conditions similar to those now existing in the 

almost wholly by those who have been brought region. 

in by the petroleum industry. Volcanism was rare during the Tertiary 

GeoZogy.-Granitoid rocks, part of the batho- period, and only in the San Emigdio l\1ountains 

lith of the Sierra N m7 ada, together with vari- are there outcrops of Tertiary igneous rocks. 

ous schists, crystalline limestones, and other These rocks, which are basaltic and and_esitic 

metmnorphic rocks-the I~mnants Of the rocks .flows and tuffs, are only a few ·hundred feet 

into which the granite was intruded--form the thick. · 

foundation upon which rest the Tertiary sedi- The structure of the d1strict is complex. 

mentary formations. The granitoid rocks are The foothills of the Temblor Range, in the 

probably of late Jurassic 'age, but the age of western part, are closely folded after a fashion 

the metamorphic rocks is unknown. These. similar to that of · oth~r parts of the Coast 

old rocks crop out io. only a small area, for in Ranges; the San Emigdio Mountains are 

n1ost of the· district they are buried under a broken by innumerable faults. 

thick coYer of Tertiary and later sedimentary In the central part of the Temblor Range 

beds. Cretaceous rocks are not ex:posed, but the beds are closely folded and even crumpled, 

they probably underlie ~ small part of the but !ti the. outer hills the folds are fewer and 

north end of the dist_rict, beneath the Tertiary more open, and- in the -outermost foothills 

rocks. along the bord,er of San Joaquin Valley the 

The l''ertiary formations are at least 18,000 folds are broad and open and extend froni the 

feet thick They rnnge in age from Eocene to main range into the valley. It is about these 

late Pliocene and are in the main composed of obliquely trending f9lds ·that the petroleum 

poorly consolidated sands, gravels, and clays, has accumulated. There are very few faults 

but in' the central part of the section there is a in this western part of the region. . ·. . 

formation (of Miocene age) about 4,800 feet The chief line o.f fractlire in the San Emigdio 

thick com posed largely of the remnants of Mountains is the San Andreas fault, or ''earthdiatoms (siliceous marine plants of minute size). quake line," as it is commonly known, which 

This formation is the one in which the petro- passes through the central part of the mop.nleum originated and in or about which the tains. Movements along this line have been 

con1mercial accumulations of oil are now found. profound. The other faults in the San Emigdio 

Sedimentation was not continuous through- Mountains fall into two classes~those trending 

out Tertiary time, for there are numerous between N. 40° W. and N~ 75° W. and those 

unconformities in the Tertiary section; but trending between N. 45° E. and due east. 

n1ost of the periods of erosion to which these Along some of these faults the movement has 

unconformities correspond were short, and been great, though not so great as along the 

during many of them only a relatively small San Andreas fault. 

pa1~t of the region was und_ergoing erosion. Production of oiZ.---The deposits of asphalt 

Most of .the Tertiary beds were laid down in and seeps of oil in this region were known to 

9 
lQ THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART. I. 

the earliest settlers, but not u:ritil the late in a hole drilled with rotary tools and the well 

eighties was any attempt made to mirie either bemg finished with standard tools. Most wells 

oil or asphalt, and the real developme.nt of the drilled near the outcrop are drilled with 

oil field did not commence until 1900~ · Up to standard tools, as are also some of the deep 

. ·.January 1, 1918, the field had produced more wells. A few ~ompanies drill the entire hole 

than 2,827,900,000 barrels of oil. with rotary tools, bu~ fortunately this custom 

The largest well in the field was well No. 1 is becoming less popular than-formerly .. 

of the Lakeview Oil Co:, which flowed for 18. ·~he productive wells range in depth from 

·months and is said to have produced more than about 500 feet in the western part of the field, 

8,000,000 barrels of oil and to have had a near the outcrop, to more th~n 3,500 feet in the 

maximum daily production of about 65,000 eastern part. 

barrels. The cost of drilling varies greatly, but in 

A large number of wells produced oil, when 1914 a price commonly paid t~ contract rotary 

·first drilled in, at a rate of several thousand drillers for drilling to the point where water 

barrels daily. These wells are chiefly those in was shut off was $4.{)0 a foot of hole. 

the parts of the field where the oil sands lie Up to the end ofJune, 19~ 7, more than 2,200 

deep, although in places big wells haye_l?een wells had been drilled in· the Sunset-Midway 

obtained at a distance no greater . than half field, and on that date 1,840 were producing. 

a mile from the outcrop, the oil coming from a Geologic occurrence of petroleum.-The pedepth of less than 1,200 feet. In July, 1917, troleum. has originated .in the diatomaceous . 

the daily yield of the·averagewell was 54 barrels. shale formations, chiefly from the alteration of 

The oil range's in gravity from less than 11° organic matter contained in diatoms and foraBaume (specific gravity, 0.9929) near the out- minifers, b.ut probably in part also from the 

crop to 31° or 32° Baume. (specific gravity, alteration of ·terrestrial vegetal debris. 

about 0.8641) in the part of the field where the Some of the oil now contained in the producoil comesfrom5reat.depths .. The averagegrav- tive pools has originated ·in the part of the 

ity of the oil obtained from the sands Iiear the region in which these pQols occur, but much 

outcrop is between 14° and 18° Ba;ume (specific of it has been formed in the shale that lies 

gravity, 0.9722 to 0.9459); that of the oil beneath San Joaquin Valley. The oil has 

obtained in the Buena Vista Hills and other migrated from the beds beneath the valley to 

pa.rts of the field where the sands lie deep is the foothills and coilected in the small anti21 ° to 28° Baume (specific gravity, 0.9271 to clines that extend from the hills out into the 

0.8860). The oil normally carries but little valley. 

gasoline, the proportion distilling at a tempera- The reservoirs from which the wells ·derive 

ture of less than 150° C. being usually less than their oil are chiefly the late Tertiary (Miocene 

4 per cent. · or Pliocene) sandy beds that rest unconformIn the Buena Vista Hills the beds lying ably .upon the diatomaceous shale. Sandy 

above the oil-bearing sands contain q dry" lenses within the shale yield a small proportion 

gas under heavy pressure, commonly as much of the oil .. 

as 1,000 pounds to the square inch and ill one • The oil-bearing beds in, the late Tertiary 

well reported to be more than 2,000 pounds to sequence are feebly consolidated coarse and 

, th~ square inch. fine sands that range in thickness from a few 

Five 8-inch pipe lines serve. the field, and the feet to a few hundred feet. These beds crop 

maximum· capacity for all is about 145,000 out in the foothills of the Temblor Range, and 

b.arrels daily. Two lines take gas from the their line of outcrop marks the western limit 

field, one to . Ba~ersfield and the other to of the main productive field. . Toward the 

Los Angeies. east the prod_uctive oil sands are buried proGasoline is. :c squeezed" from the gas at a gressively deeper beneath 't:l~e ~urface. In the 

number of plants in the field, and the average eastern part of the field the productive sands, 

amount reco"ered in 1916 was between 1 and 3 which are usually 10 to 50 feet thick, are intergallons from 1,000 cubic feet .Jf gas. ·. spersed with barren beds of equal· thickness 

Most of the recent deep drilling (1916) has through a section 600 to' 800 feet thick. Near 

been done by a combination of the rotary and the outcrop the total thickness of the zone 

standard methods, the water string ·being set containing oil sands is rarely more than 200 or 
SUMMARY OF RESULTS. 11 

300 feQt, but the portion of it compos.ed of oil 

sand is greater there than in the parts of the 

field where the sands lie deeper. 

The sands impregnated with oil bear a fairly 

constant relation to the diatomaceous shale, 

the richest sands lying close to the _contact 

with. that shale. These oil-bearing beds are, 

however, not of the same age throughout the 

field, for the formation of which they are a part 

rests unconformably on the shale, and younger 

beds abut against the shale in .the western part 

of the field than in the eastern part. 

The oil has evidently n1oved chiefly through 

the lowest part of the formation that rests 

upon the diatomaceous shale, as these beds are 

fairly porous and offer less resistance to the 

movement of 'the oil than the shale. The 

· movement is therefore chiefly parallel to the 

plane of unconformity-that is, to the top of the 

shale. Near· the outcrop, either by fractionation or by reaction with alkaline water, the 

oil Becomes very viscous or tarry and ·seals 

more or less completely the beds through which 

the oil is moving. When this avenue of escape 

to tho surface is closed the oil moves out from 

the plane of unconformity through the more 

porous of the beds in the formation that rests 

upon the shale. The n1oven1ent of the oil in 

this manner is rendered easy by the fact that 

the younger formation was laid down in a 

transgressing sea and the different beds in it 

abut .against the shale just as horizontal layers 

o~ sand held in a huge bowl would rest against 

the sides of the bow:L The distance that the 

sands which extend out from the unconformity 

are filled with oil is variable, but each sand beyond the point at which it contains oil is. 

:filled with water. 

When viewed in cross section the arrangement of the oil. sands near the outcrop may be 

compared to a branch from one side of ·which 

a nutnber of parallel twigs extend, the oil sands 

along the unconformity being the branch and 

the pil sands in the formation that rests upon 

the diaton1aceous shale the twigs. 

Along the anticlines that are separated by 

synclines from the outcrop of the oil sands the 

oil has collected in sands that lie some distance 

above the plane of unconformity. This oil has 

evidently moved vertically through the lenticular sands. In any sand that contains oil and 

gas in these outer anticlines there is a notable 

tendency for the gas to occupy ·the higher 

parts of the fold and the oil the lower parts or 

saddles of the same Jold. In the outer anticlines .dry gas has collected 200 or 300 feet 

·above the oil. 

In parts of the field where the oU is buried 

more than 2,000 feet a zone of tar-filled sand 

lies less than 1,000 feet below the surface. 

This zone is believed to mark the place where 

the upward-moving hydrocarbons have met 

and been oxidized by surface waters. The 

evidence indicates that these hydrocarbons 

have moved more. or less vertically through 

the intervening 2,000 feet of beds. They were 

probably in a gaseous state. 

The gravity of the oil varies with the grain 

of the sand, the oil being lighter in the finegrained beds; wit4 the distance from the outcrop; with the relation of the oil to mineralized water, the oil in contact ·with water of 

certain types being tarry; and with the positior,t on the· fold, the oil being lighter on the 

higher parts of the anticline. 

The pressure under which oil and gas are 

now contained in the sand probably affords no 

measure of the pressure that caused them to 

accumulate. The hydrocarbons have probably changed since they first entered the sand 

they now occupy, both viscous material that 

sealed reservoirs and lighter portions that 

increased the pressure of . the hydrocarbons 

contained in the pool being formed. 

The tarrification of the oil is caused chiefly 

by the addition of sulphur derived from the · 

sulphate-bearing surface waters. In places 

this same reaction has caused the formation 

of d~posits of sulphur. 

·. Oil sands and water sands are interdigited, 

and neither the water nor the oil can be considered as indigenous to the· bed in which it is 

now found. Furthermore, analyses of the fluids 

now contained in the various sands do not 

indicate directly the character of the fluids 

those sands originally contained, for both oil 

and water have been altered by chemical react,ion.that involved them both or involved one · 

of them and ·certain solid minerals contained 

in the sediments. 
0 0 
THE SUNSET-MIDWAY OIL FIELD~ CALIFORNIA. 

PART I. GEOLOGY AND OIL RESOURCES. 1 

By RoBERT W. PAcK. 

INTRODUCTION. inexhaustible, and even many of the men who 

PURPOSE OF THE REPORT were actively engaged in the production of .. 

petroleum paid little attention to the question 

During the last year or two, and especially of the total supply but were content if their 

since the entrance of the United States into production satisfied the daily demands made 

the war, a large amount of earnest considera- upon them. The pronounced rise in the price 

tion has been given to the problem of the of gasoline in 1915 was, however, too apparent 

available supply of petroleum, for so many of . and affected direc·tly too many people to pass 

the industries of the country and so many. of unnoted. A number of possible causes for· 

the devices used in carrying on the war are this abrupt rise hav-e been suggested, but whatdependent upon petroleum and its products ever may have been the immediate causes, one 

that it became of the greatest importance to effect has been that the attention o~ the people 

know to just what extent we might rely upon has been called in no unmistakable manner to 

the resources of our own country to supply the fact that the supply of petroleum is really 

these demands. Many estimates of the quan- limited, and that sooner or later t~e pijce of 

tity of oil remaining available have been made, gasoline and of all other products of petroleum 

and, as is natural, a variety of conclusions as is sure to rise. 

to the exact amount have been reached; but So long ~s the limited nature of the supply 

without ·exception these estimates show· that ofepetroleum was not appreciated it was ~ot 

the known supply is relatively small compared possible to do anything toward. conserv~g 

with the present demand, and especially small tllis supp~y, but now that the fact IS becommg 

compared with· the even greater demand that more and more widely accepted that sooner or 

it appears certain is to be made .upon this later the world must get along somehow with 

supply in the near future. The petroleum a greatly reduced supply of petroleum many 

deposits of the United States are wonderfully things that were before considered impracticarich, a vast quantity of .oil has been·taken fr?m ble are being done, and the producers of petrothem, and an even greater amount still remains leum are giving earnest thought to the conto be taken; ye.t, if the next generation is not se:rvation of the oil-not by locking it up for 

to feel the pinch of the dwindling supply, the the use of .the next generation, but the true 

present generation must use all du·e care so to co~servation that consists of utilizing to the 

handle these deposits as to permit the le8,f3t utmost, without waste, that which the country 

possible waste. · possesses. 

For a long time the general. public refused to Within the last decade great changes have 

believe that the supply of oil was other than been made in the :p::tethods of handling oil. 

1 'rhls report on tho Sunset-Midway field is published in two pnris. 

Part I (Professional Paper 116), by R. W. Pack, describes the general 

geology ot tho Sunset-Midway region and the development and underground conditions In tho productive field and discusses also the origin 

fiDel migration or tho oil. Pnrt II (Professional Paper lli), by G. ~· 

H.ogcrs, contains analyses of tho oil, gus, and oil-field waters and a discussion or their composition in relation to their geologic occurrence; 

some figures on tho goothormnl gradient; and a brief discussion of the 

invasion Of Oil SfiDdS by Water. 

The mechanical devices and methods of drilling, of transporting, and of refining have been 

so greatly improved that oil may now be produced and taken to the ultimate consumer in a 

much more efficient manner than formerly. 

Yet in many and perhaps in most fields the 

13 
14 THE SUN_SET-M~DWAY OIL FIELD, CALIF.-PART I. 

methods of production leave much to be de- this study should be extended over the whole 

sired, for no systematic effort is.· made to use pool, not confined to a part of it, for a general 

the mass of data furnished by the wells or to study of the field brings out features that are 

weave together these data intQ a picture show- not at all apparent in a study restricted to a 

ing t,he underground conditions, which may small area, and· features which appear at first 

be used in the guidance of future drilling. No sight to be quite unusual and- which leaq to 

matter how efltcient. the ·mec:lu~,nical work of the supposition of unique and special condi- . 

drilling or of producing oil may be,· it is im- tions are found when the full story is known 

possible to recover the maximum amount of to accord fully with the accepted theories. 

oil, or even to produce oil efficiently, unless the Viewed in a broad way th~ petroleum inunderground conditions ·are clearly understood: dust.ry may be divided into three major 

Lack· of knowledge of the underground condi- parts-one· concerned with the search for protions is in the long run vastly more productive ductive pools, another with the draining of 

of waste than faulty methods of drilling or of ·these pools, and the third with the handling . 

production. of the oil after it has reached the surface. 

Of course much of the ignorance of under- It is commonly supposed that the geologist 

ground conditions is unavoidable, for in the is concerned with only the first of these probvery nature of· things the driller8 of the first lems, and that o'nce the position of the new 

.well in a ·new pool must go ahead more or less field is. pointed out his duties are ended. But 

blindly; but with the information derived in reality ~he efficient handling of any pool 

from this first well and from' each succeeding depends upon the geologist as much as upon 

well, .drilUng in that pool should become less the engineer or the well driller, especially such 

and less a matter of faith and more and more pools as those which occur in the feebly conan exact science. The determination of the solidated sedimentary beds of the Tertiary. 

position 'of the t.op of the producing zone, The proper interpretation of the well records 

important as ·such a determination may be,. and the correlation of these daOO. with the 

is the least part of the work, for to be of r~al areal ge·ology depend upon the geologist more 

value the study of the well data should show than upon anyone· else, and his work should 

the position of each oil sand within the pro- afford the comprehensive picture of the underductive zone, and, what. is in many places of ground conditions that is so essential to the 

even greater significance, the position of ea<Jl .petroleum operator. 

water sand. It should show the character of The search for new pools, whic~ is to-day 

the productive oil sands, the position and occupying the· full attention of most of the 

character of the strata in which water may be petroleum geologists of the country, will 

shut off, the position and character of the gas become increasingly keen as the production of 

sands, and a multitude of other 'like facts. oil decreases and the demand continues to 

Then as the natural conditions-that is, the con- increase, but the geologist will in the future 

ditions existing before drilling commenced- render. his chief service to the petroleum inbecome better and better' known it becomes dustry through intensive studies of the propossible to· understand the nature of the con- ductive fields, made for the purpose of aiding 

ditions produced when the m·ovement of the in the efficient extraction of the oil. 

fluids is interfered with by .the wells that are. During the last 18 years the United States 

drilled, and to predict in a measure the ·probable Ge9logical Survey has been carrying on an inlife of a well or its rate of decline,· the drrection vestigation of the petroleum resources of Caliand rate of movement of water, the probable fornia, having examined not only practically 

production ofnewwellsJ and other like features. all the major productive field but also several 

In order that this result may be attained large areas that offered some prqmise of yieldand that each new wel_l .in a field m·ay not be ing. oil, the attempt being maqe to precede 

a. special and isolated venture, it is necessary drilling and to outfuie those areas which were 

that a systematic ·record be kept of the data of greatest prospective value. The results of 

furnished by the wells, and that the geologic sig- much of this work have been set forth in anumnificance of. these data be interpreted_by some- her of-published reports. The reports that ar~ 

one competent to make such interpretations.' conc~rned with the productive fields present as 

MoreoverJ it is particularly important that full a discussion of the underground conditions 
INTRODUCTION. 15 

as was justified by the data obtained from the ing in the western part ·of the San Emigdio 

drilling done up to the ,time the fields were Mountains and for the workers on the San Emigexamined. . ' di~ ranch this part of the region is inhabited 

The present report is twofold. In the fir.st only by those who have been brought there by 

place the geology of the general area of which the petroleum industry. The chief settlethe productive fields constitute a· small part is ments in the Sunset-Midway field are Maricopa, 

described; then into this setting are fitted the Taft, and Fellows. At the north end of the 

intimate details of the geology of the produc- area shown on Plate II is McKittrick, ·which is 

t.ive areas as interpreted .chiefly from a study the railroad shipping point for the McKittrick 

of the records of the wells. The interpre.tation · oil field. · · 

of the geologic conditions in the productive The Sunset-Midway field is served by the 

fields is based on the data made available by Sunset Railroad, which is operated jointly .by 

drilling that had ·been done pi·ior to July, 1916. the Southern Pacific and the Atchison, Topeka 

It is not' presented as a completed picture ac- & Santa Fe and joins the main lines of those 

cuTate in all its details; in the very nature of roads at Bakersfield, from which the distance 

thillgs it can not be that. It is presented, l.s 315 miles by rail to San Francisco and 170 

however, as an interpretation that may serve miles to Los Angeles. A branch line· of the 

as a framework into which to fit other data Southern P·acific connects Bakersfield and 

that may become available from time to McKittrick. Numerous auto stages are run 

time, and it should thus serve in the guidance between Taft and Maricopa and Bakersfield, 

of fut\}re work. The wri.ter has taken the op- and between Taft and the coast at Los Angeles 

portunity of gi\7 ingt also certain data and con- and Pismo. 

elusions which will be of interest to the student Excellent. roads connect Taft and Maricopa. 

of the geology of the Coast Ranges if not to the with Bakersfield and with the State highway 

oil man, as well as data regarding the produc- that runs up San Jo~quin Y alley and over the 

tivity and rate of exhaustion of oil sands and Tehachapi J\1ountains ~o Los Angeles. A netthe interference of wells, which will be of in- work of excellent, poor, and indifferent roads 

terest to the engineer if not to the geologist·. extends through the oil field and along the 

LOCATION OF THE FIELD. . western edge of the valley ·to and beyond · McKittrick. 

The Sunset-Midway oil field lies in the western part of Kern County, Calif., about 40 miles 

southwest of the city of Bakersfiel~. It extends over part of the northeastern flank of the 

Temblor .Range, over the outlying foothills 

ranges known as the Buena Vista and Elk 

hills, and over a portion of the western border 

of the almost level floor· of the San Joaquin Val1ey. The location of this field and of the other 

prin~ipal oil fields in California is shown on 

the index map (fig. 1). The region shown on 

·the geologic map (Pl. II) covers not only the 

productive oil field, but also a considerable 

part of the northern slope of the San Emigdio 

J\1ountai.ns, which lie southeast of the oil field 

and in which rocks that lie stratigraphically 

below the oil-bearing 1neasures are exposed. 

. 'rhe productive field is shown in detail on Plates 

I, III, and XLIII. 

Most of the hilly part of the area shown on 

the geologic map (Pl. II) and also a large part 

of. the floor of San Joaquin Valley immediately 

adjacent to the hills is unsuited for agriculture, 

and except for a few settlers who are dry f.armRELIEF. 

. San Joaquin Valley,· at whose south end lies 

the Sunset:..Midway oil field, forms the southern 

half of the structural depression. that occupies 

the central part of California and extends from 

the Klamath Mountains, near the north line 

of the State, to. the San· Emigdio and Tehachapi mountains. On the east the valley is 

bordered by the . Sierra Nevada,· which rises 

gently, almost imperceptibly at fust, through 

a broad belt of foothills to lofty snow-capped. 

summits. On the 'west are the Coast Ranges, 

which, though far lower than the Sierra Nevada, 

for the most part rise n1ore abruptly from the 

plain and n1ark the valley's edge more sharply. 

On the south San Joaquin Valley is limited by 

the San Emigdio and Tehachapi mountains, 

which in places rise more than 7,000 feet above 

the valley within a ~istance of only 10 miles 

from its edge. These mountains join the 

Coast Ra~ges with the Sierra Nevada and 

forin a rugged mountain barrier between San 

Joaquin Valley on the north and the Mohave 

Desert on the· south. 
16 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

South of San Francisco the Coast Ra;nges erly than the mountainous area as a whole and, · 

occupy the reg~on lying between San .Joaquin cutting. across it, run out into San Joaquin 

Valley and th~ ocean. They comprise a .num.:. Valley. On account of this oblique arrangeFIGURE 1.--:-Index map of a part of California showing oil fields described in published reports. 

ber of approximately para.lle~ ranges. sep.arated I m. ent . o.f the individ.ua1 range~ the western 

by structural valleys .of variable Width. · The border of. San Joaqum Valley Is ·formed not 

individual ranges trend somewhat more east- by a single range but by -two, the: Diablo and 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE IV 

A. MIDWAY OIL FIELD IN 1907. 

Looking northeastward from Twenty-five Hill across present site of Taft. Buena Vista Hills in middle distance and Elk Hills beyond. Photograph by Ralph Arnold. 

B. SUNSET OIL FIELD IN 1901. 

Looking easLward from souLhwest corner of NW. t sec. 2, T. ll N., R. 24 W. 'Fhotograph by G. H. Eldridge. 
0 

INTRODUCTION. 17 

· Tmnblor ranges. On the eastern flank of the. leys, which lie between the different hill groups, 

Te1nblor Range, the more southerly of the two, outlin~ the position of the downward-arching 

lies the Sunset-~fidway field. · folds. Not only do the larger topo.graphic . 

This range extends,. as an elongated mass, 'units reflect the major structural features, 

from the vicinity of the north line of Kern but even the position of the smaller units is 

County southeastward some 70 miles to Sun- determined by the lesser features, as is well 

set, where it joins the eastward-trending San shown in the northern part of the Buena Vista 

En1igdio ~1ountains. For the most part the · I-Iills, where, inste-ad of a single ridge, a collecsouth end of the Temblor Range presents no tion of low, approximately parallel ridges 

very striking topographic features, and as seen faithfully ou_tline the position of the numerous 

from the central part of the valley it appears small anticlinal folds that together forn1 the 

to be no n1ore than a group· of lo'\V, fairly evenly general anticline. 

rounded, barren hills .. The average altitude of The topographic reflection of the broader 

the crest of this part of the range is a little o·ver structural features is quite as strongly·. shown 

3,900 feet above sea level, or between 2,000 in the San Emigdio Mountains as in the · 

and 2,500 feet above the valley floor at the Temblor Range, .for the San En1igdio and the 

edge of the hills. The 1naxin1um altitude, Tehachapi mountains constitute essentially 

3,651 feet,isreached'in~dway Peak. Through~ a fault block that has been uplifted with respect 

out its length the, Teinblor Range proper is to the valley on the north. Within the San 

narro,v-, being in few places more than 10 miles Emigdio Mountains, however, the structure 

across. Near the south end, however, two is so complex that, except for the San Andreas 

groups of low hills project eastward into San fault, no one feature dominates su:ffi.ciently 

Joaquin Valley and, together with the main to be ·as· strongly reflected in the· topography 

range, forn\ a belt of hilly land almost 20 miles as the lesser features in the Temblor Range. 

in width, lying between San Joaquin 'Valley In consequence the difference in· the lithology 

and the Carrizo Plain, the structural depres- of the rocks plays a much greater part in. 

sion that limits the Temblor Range on the determilling the form of the surface here10 

southwest. These two foothill ranges, the arid the most prominent topographic feature 

Buena Vista and Elk hills, are separated from is the change from the abrupt and rugged slopes 

the main range and from ea.ch other by broad, of the higher hills, formed of the- resistant 

gen~ly sloping valleys covered with gravelly crystalline rocks, to the broadly rounded 

wash from the hills. · slopes of the foothills, formed of the softer 

Although· the larger fe~tures of the topog- Tertiary sedimentary rocks. Parts of the low 

raphy are broadly rounded, the smaller fea- foothills, particularly thos~ formed of .the 

tures are sharply sculptured, the drainage coarse gravelly beds of the upper ~ocene; 

courses being deeply cut and the canyon sides have been carved into typical badlands, and of 

in· places standing at slopes of 40° or steeper. such a nature are most of Wheeler Ridge and 

The hills are so bare of vegetation that even .the low hills near the mouths of Salt and 

the 1ninute features of the sculpture are readily Tacuya ·creeks. A good t)Xample of badland 

visible and stand out strongly in the oblique erosion of this type is shown in Plate V. 

light of early morning or late evening. 

One of the n1ost notable features in the topography of this area is the remarkable control 

exercised by the geologic structure. All the 

principal hill groups are formed by structural 

uplifts, and the broad valleys between by structural depressions. Thus the main Temblor 

Range is broadly anticlinal, being an assemblage of close folds whose general effect has 

·been a doming of the strata; the Buena Vista 

IIills and the Elk I-Iills are also the topographic 

eA1)ression 'of anticlinal structure; and the 

gently sloping ~fidway and Buena Vista val1092880--19----2 

CLIMATE AND VEGETATION. 

The climate of the south end of San Joaquin 

Valley is semiarid, the rainfall rarely exceeding 

10 inches a year and the average being about 

6 inches. The Temblor Range is 1nuch lower 

than the ranges west of it, and in consequence 

the moisture that travels eastward from. the 

ocean. and passes over ·the moun_tains lying 

close to the coast is not halted by the Temblor 

Range . but i~ carried across . San Joaquin 

V ailey and precipitated as snow or rain in the 

upper slopes of. the Sierra Nevada. Thus the 
0 

18 THE SUNSET-MIDWAY OIL. FIELD, CALIF.-PART I. 

precipitation' 'on.'' the eastern. 'slope of . the parts of the area were examined independently, 

Temblor Range is far· too small to support some for one immediute purpose and so:::1e for 

perennial streams. ·Most of the stream valleys another. All the work, however, formed a 

. carry water during only a·· few days in the part of the general scheme that the Survey has 

winter, and many for only a few hours follow- been following in an examination of the petroing heaVy rains, for the vegetation is so scant leum resources of California. 

on the hills 'that qut a small proportion of the The areal geology of the north. flank of the 

rainfall is .held in the ground. . Sari Emigdio Mountains was mapped in 1911 

. Th~·San Emigdio Mountains rise to altitudes and 1912 by the writer,. with the assistance 

of over 7,000'feet, and in many yeurs the higher during the first season of A. T. Schwennesen 

por~ions are snow covered from November and ·during the second season of lL G. Davies. 

until May. Both S~ntiago and San Emigdio Similar work had been done in the. Temblor 

creeks, which drain the higher parts of the Range in 1908 by Ralp~ Arnold and H. R. 

west end of ·these mountains, ·carry running· Johnson, and the results were published in 

water throughout the year. Practically all 1910.1 This work in the Temblor Range was 

the normal flow of San Emigdio Creek is now chiefly in the nature of a reconnaissance, and 

used for irrigation, but doubtless some day in consequence many parts of the area, parthe flood· water will be· stored and a much ticularly the outlying foo~hills, were not exlarger acreage· in the valley watered. The amined in the detail of which later developdeeply in'trenched canyon in the lower 3 ·miles ments have shown them worthy. A ·more 

of the course of San Emigdio Creek offers an detailed examination of the foothills of the 

excellent reservoir site for the impounding of main Temblor Range and of the Buena Vista 

these wate:rS. The water of Santiago Creek a~d .Elk hill~ was therefore mad~ by the 

contains too large an amount of mineral salts writer in the summer of 1914. During the 

to be serviceable for irrigation, and, moreover, same year a small area near Pattiway, in the. 

the flow during the summer months is very west end of the San Em.igdio Mountains, was 

·small. Buena Vist·a Lake· is an artificial lake mapped by the writer with the assistance of· 

whose water is used for .irrigating the San W. A. English and Wallace Gordon. 

Joaquin Valley lands north of the Elk ·Hills. The writer has found no occasion to alter The water is not.potable. . the chief geologic conclusions expressed by 

The eastern flank. of the Temblor Range Arnold· and Johnson in ·the .preliminary reand the outlying foothill ranges support no port of the geology of the Tem.blor Range, 

trees other than those· that have been planted but he has been able to correct some minor 

about the different camps and · carefully ones and to add a very considerable amount of 

watered, the natm:al ·vegetation being· limited detail that is of prime importance in the illto small shrubs. and ·a sparse growth of grass tensive study of the underground conditions 

whiCh serves as winter feed for sheep. The in the productive :fields. ' ' 

higher portions of the San Emigdio Mountains . During the summer ·of 1914 and a couple of 

are· covered by small) pine, oak, and juniper, weeks in the fall.of 1916 the writer collected a 

and on the lower· slopes grass grows suffi- great mass of detailed information regarding 

ciently thick to make a good rang~ for cattle. underground conditions. Through the liearty 

Heavy localized storms or cloudbursts are cooperation of the operators, logs of practicnot at· all uncommon ·in the San Emigdio ally every ·w:ell drilled up to July, 1916, in the 

Mountains. ·These storms have at several Sunset' and Midway fields were obtained, as 

places torn trees and soil alike from the steeper were also detailed maps, records of producslopes, leaving great brown ·scars of barren· tion of individual wells and of groups of wells, 

rock that may ·be seen for miles and carrying gravity cuts, and samples of oil sand, of oil, 

huge masses of rock and trees for great dis- and of water. Indeed the mass of data has. 

tances, ·in places far out· into· the valley · been so great and its character so varied that 

(See Pl.· VI.) · its proper assimilation has been no small task. 

FIELD WORX AND ACKNOWLEDGMENTS. . . 

. The field work upon which this report is hased 

During 1914 G. S. Rogers was in the :field with 

the writer investigating the geologic relations 

1 Preliminary report on the M:cKittrick-Sunset oil region, Calif.: U.S. extended over a nuinber .of years, for different Geoi. survey Bull. 406, t9to. 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE V 

z "' IT' (/)::2:::0 9 >rnrn 

Z:;:.:J""'"~ ;.C: 'T1 r- :::o :;o -, z :>-,...,-i 

~;jO 

- (~ r- {/l- ::> Cl!"T"l:Z 

0 c:: 0 .. -.. ~ () :.,. 0 

;,..nrn 

ro" 

~Ii ::v ~ O(g:-j 

Ill :::0 ='·· 

t:~~ >--t 0 

::z 

FOOTHILLS FORMED OF TERTIARY ROCKS ON WEST SIDE OF SALT CREEK. 

Looking westward from divide between Tacuya and Salt. creeks about I mile from edge of San Joaquin Valley. Sharp ridge at extreme left. formed by Tertiary volcanic rocks lying in the Vaqueros formation. Syncline in center occupied by diat.omaceous Maricopa shale. Badlands carved in gravels in the Vaqueros formation. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER llG PLATE Vf 

A. BOULDER OF GRANITIC ROCK IN SAN JOAQUIN VALLEY. 

This boulder lies 2 miles from the mouth of Tacuya Canyon and must have traveled that distance over a surface which is inclined only about 

200 feet in a mile. 

B. GRANITE BOULDER IN UPPER PART OF MARICOPA SHALE WEST OF FELLOWS. 

This boulder has weathered out of a le'!S of granitic material bedded with fine diatomaceous shale. Photograph by Ralph Arnold. 

C. WEST END OF SAN EMIGDIO MOUNTAINS. 

Looking eastward from foothills 1 mile west of Pioneer. Refinery at extrei:ne left. Higher parts of San Emigdio Mountains at right. Photograph by G. H. Eldridge. 
• 

INTRODUCTION. 19. 

of oil and water. :Much of the information 

pertaining to the· development work in. certain parts of the field was collected by him. 

To his colleagues on the ·survey, particularly to those who ar·e engaged in the study of 

oil fields in other parts of the United States, 

and to l\1r. M. R. Campbell, under whose 

direction the work was started, the writer is 

indebted for many helpful criticisms and 

suggestions. 

It is with a feeling of genuine pleasure tha~ 

the writer finds an opportunity of expressing 

his appreciation of . the hearty cooperation 

extended to him· in his work by the operators, 

and of their evident effort to make his stay in 

the :field both profitable and pleasant. To 

nrune all who have so assisted would mean the 

construction of a list of almost all those engaged in the development of the field, and. of 

that space here yrill hardly admit. But to the 

following the writer is especially indebted: 

:Messrs. l\1. E. Lombardi, G: C. Gester, E. G. 

Gaylord, F. B. Tough, Dr. E. A. Starke, R. A. 

Stoner, Capt. William Matson, P. M. Paine, 

Thomas Kingston, T. A. O'·Donnell, F. W. 

Fuqua, John Gom·lay, E. 0. Faulkner, F. C. 

Ripley, Capt. John Barneson, A. L. Weil, B. E .. 

Parsons, and R. E. Sperry. · 

Through the courtesy of the officers of the 

Kern Trading & Oil Co. the 'vriter is able to 

p1~esent the topographic map of the SunsetMidway oil field that accompanies this report 

(Pl. 1). That map has been compiled· from a 

topographic atlas made by the company for 

its own use in the field. 

BmLIOGRAPHY. 

The following is a list of the more· important 

papers describing the· geology or the occurrence of petroleum in the Sunset-Midway oil 

field: 

1868. Cronise, T. F., The mineral wealth of California, 

696 pp. Brief mention is made·(pp.117, ll8) ~f 

:··.'~e oil seeps about Sunset. Th'e description of 

the work done southeast of ''Buena Vist~ Lake" 

and the shipm,ent of sev~rnl thousand g..tllons of. 

oil to San Francisco evidently has reference to the 

operations about what is now the McKittrick field. 

1894. Watts, W. L., The gas and petroleum yieldingfo:r:mations of the central valley of California: ·California 

State Min. Bur. Bull'. 3, 100pp., maps, plates, and 

figures. Contains a careful description of .the de-

. velopment work that had bee:t:t done in the Sunset 

field up to 1894, gives the logs of most of the wells 

at Old Sunset, ~nd the analyses of water from 

seveml of these.wells. 

1900. Watts, W. L., Oil and gas yielding formations of 

C.:tlifornia: California State Min. Bur. Bull. 19, 

236 pp., maps, plates, and figures.· Contains. a 

discussion of the geology of the productive fields 

in California, detailed descriptions of the development; and a genernl discussion of the geologic 

range of the oil-bearing formations in California 

and of the relation of structure to the occurrence 

of petroleum. 

1903. Eldridge, G. H., The petroleum ·fields of California~ 

·u. S. Geol. Survey Bull. 213, pp. 306-321. Conta.ins a brief outline of the geology of the Midway 

·and Sunset fields. Eldridge correlated with the 

San Pabloform::~.tion the poorly consolidated sandstones and clays that overlie the siliceous shale of 

the Monterey group. 

1903. O'Neill, Edmond, Petroleum in California: Am. 

Chern. Soc. Jour., vol. 25, pp. 699-711. Gives 

analyses of various California oils, two from the 

Sunset field among them. 

1904. Cooper, H. N ., ()hemical an.tlyses of California 

petroleum: California State Min.· Bur. Bull. 31 

(also inserted as appendix to Bull. 32). Analyses 

of oils'from two wells in the Sunset field are included in the list.· 

1904. Prutzman, P. W., Production and uses·of petroleum. 

in California: California State Min. Bur. Bull. 32, 

230 pp., maps, pLttes, and figures. Contains 

maps of the Sunset and Midwc1y fields show.ing 

owners~ip and location of the wells. The principal part of the report consists of notes concerning the chemical and physical properties of California oils, their uses, and methods of refining. 

1905. Anderson, F. M., A stratigraphic study in the Mount 

:Ciablo Range of California: California Ac:1d. Sci.. . 

Proc., 3d ser., Geology, vol. 2, pp. 156-248, pls~ 

13-35, 1 ma.p. · 

1908. Anderson, F. M., A further stratigraphic study in 

the Mount Diablo Range of California: California 

Acad. Sci. Proc., 4th ser., vol. 3, pp. 1-40. 

In both of these papers the salient features of 

the geology of the mountains on the '~est side of 

San Joaquin Valley are discussed, and in the first 

paper. many fossils found in the Tertiary formations are described and figure( The region 

described most in detail lies somewhat north of 

the Midway field. 

1910. Arnold, Ralph, and Johnson, H. R., Preliminary 

rep or~ on the McKittrick-Sunset oil region, Calif.: 

U. S. Geol. Survey Bull. 406, 225 pp·., 5 pls., 2 

figs. The geology of the· eastern flank of the 

Temblor Range is mapped and described, and the 

produ~tive oil fields at McKittrick, Midway, and 

Sunset are discussed in detail. The southern part 

of the region discussed.by Arnold and Johnson is 

<I:escribed in the present report, and their work 

has been used freely in its preparation. 

1911. Allen, I. C., and Jacobs, W. A., Physical and chemical properties of the petroleum of the San Joaquin · 

Valley, Calif., with a chapter on analyses of natural gases from the southern Californi.l. oil fields. 

by G. A. Burrell: U. S. Bur. Mines Bull. 19. 

Contains analyses of oil and gas from the Sunset 

and Midway fields. · · 
·20: THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

1911. Anderson, F. M., The N eocene deposits of Kern is composed of igneous and metamorphic rocks 

River, Calif., and the Temblor Basin: California which reach the surface in the central part of 

Acad. Sci. Proc., 4th ser., vol. 3' PP· 73-148, the San Emigdio Mountains, ·but these rocks 

pls. 2-13. Deals mainly with the Tertiary .formations about Kern River on the east side of are of no importance so far as the presence of 

SanJog,quin V9.lley and with the Kern River oil oil is c_oncerned. The general character and 

field. The formations are, however, in part the. thickness of the several formations is shown 

same as those exposed in the Sunset-Midway field, in the accompanying columnar section (fig. 2). 

and brief mention is made of the geology of the The old t ck th t c 0 t m· the Vl·cm· 1·ty Temblor Range. es ro ~s a rop u 

1911. Forstner, William, The occurrence of oil and gas in of the Sunset-Midway oil field are those that 

the South Midway field, Kern County, Calif.: form the crystalline 1uass exposed in the central 

Econ. Geology, vol. 6, pp. 138-155, 4 figs. :Cis- part of the San Emigdio Mountains. This 

cusses the conditions under which oil and gas central rriass consists largely of pre-Cretaceous 

exist in the Midway field, and gives some data on granitoid rocks that are intrusive into rocks 

the flowing wells in the northern end of the field. 

1912. Requa, M. L., Bradley, F. w·., and Stadler, Walter, of unknown age, now altered to schists and 

Fuel resources of C':tliforniu.: Commonwealth Club gneisses. The granitic and metamorphic rocf\:s 

of San Francisco Trans., June, 1912. Contains a are the equivalent of those commonly known 

brief statement regarding the history of the Sun- as the basement complex in the Sierra Nevada,, 

set and Midway oil fields, and statistics of pro- into which they may be traced in unbroken 

duction; also a general discussion of the possibly 

productive territory, tha cost of production, and outcrop through the San Emigdio and Tehamethods of controlling development. chapi mountains.' They are p.ot exposed in 

1912. Anderson, Robert, Preliminaryreporton the geology the Sunset-Midway oil field, but they evidently 

and possible oil resources of the south end of the underlie it, buried deeply beneath the Tertiary 

San Joaquin Valley, Calif.: U.S. Geol. Survey sedimentary rocks. . Bull. 471; pp.·106-136, 1 pl. (map). This paper, 

based upon a ~ort reconn_aissance, describes the The granitic and m·etamorphic rocks are 

foothills at the south end of San Joaquin Valley, overlain by" Tertiary sedimentary rocks that 

j11st east of the Sunset field, pointing out the areas are n1ainly though not wholly of marine origin. 

that may possibly yield oil. · The oldest of these rocks exposed within the 

1914. Arnold, Ralph, and Garfias, V. R., Geology and area shown on the geologic map are comprised technology of the California oil fields: Am. Inst. 

Min. Eng. Bull. 87, pp. 383-4G9. The report con- in the Tejon formation, of Eocene age. This 

tainsin concise form the salient features regarding .formation is composed of massive arkosic sandthe geology; methods of production and trans-. stone and dark clay shale that were laid down 

portation of oil; and statistics on production of in marine waters upon a very uneven surface 

the p;incipal California fields. . of granitic and metamorphic rocks in the area 

1914. Allen, :i:. C., Jacobs, W. A., Crossfield, A. S., and . d b h S E · d' M · Matthews, R. R., Physical and chemical pr.oper- now occup1e Y t e an · nng 10 ountams 

ties of the petroleums of California: U. S. Bur. and upon rocks of Cretaceous age in the area 

:Mines Tech. Paper 74. Contains analyses or" oils now occupied by the north end of the Temblor 

f.rom Sunset and Midway fields. Range. The formation crops out in the San 

1915. McLaughlin, R. P., and Waring, C. A., PE:ltrolel,llll Emigdio Mountains and in the north end of 

industry of California: California State Min. Bur. 

Bull. 69, 519 pp. and atlas. Chapter on westside the Temblor . Range,· but not in the oil field 

fields in Kern County contains brief review ~f proper, alth~:mgh it almost certainly underlies 

geol9gy but is concerned. chiefly with the me- a part if not all of the field beneath the cover 

chanica! features of producing petroleum. of later Tertiary formations. The maxiluum 

1917. Rogers, G. S., Chemical relations of the oil-5eld exposed thickness of the Tejon is 4,300 feet. 

waters in San Joaquin Valley, Calif.: U.S. Geol. 

Survey Bull. 653. · Resting upon the Tejon is a fori.nation several 

thousand feet· thick that embraces beds:. of 

STRATIGRAPHY. varied character-coarse, ill-sorted conglomerGENERAL CHARACTER AND DISTRmU'fiON OF ate that was evidently laid down by running 

FORMATIONS. water on the surface of. the land, massive 

The rocks exposed in the Sunset-Midway marine sandstones, and fine carbonaceous clay 

field and in the foothills along the north flank shale-intermingled in a manner that makes 

of the San Emigdio. Mountains are chiefly the untanglement of the record of deposition 

sedimentary and were laid down no earlier peculiarly difficult. In the eastern part of the 

than the beginning of the Tertiary. The San Emigdio Mountains the lower deposits 

toun·dation upon which these formations rest resting on the ·Tejon ar.e chiefly marine beds_ 

• 
I 

GENERAL CHARACTER AND DISTRIBUTION ·OF FORMATIONS. 21 

that contain an excellent fauna of Oligoce~e 

age, but the overlying deposits in the same 

region are largely terrestrial beds of Miocene 

age, corresponding to those which in previous 

reports have been mapped and described a~ the 

dated sand, gravel, and clay. The lower part of 

the McKittrick group is made up of beds that 

w~re deposited in marine or estuarine waters 

and is the equivalent of the Etchegoin and 

Jacalitos formations of the Coalinga district, of 

Vaqueros formation. No satisfactory 

line of separation could be drawn between these Oligocene and :Miocene deposits, for the two grade in ~o each other, 

and in this region, where the structure is 

so conlplic&ted, the data upon which a 

separation is based must be definite or 

the separation can not be made. These 

Oligocene beds are therefore for convenience included in the:.yaqueros fornlation on the map flJld in .. 1he text descriptions. This course is cpnsidered preferable to the introducti<;>!l of a new name. 

The1naximum thiclmess of the Vaqueros 

exposed is at least 3, 700 feet. 

'rhe Vaqueros formation is overlain by 

several thousand feet of shale containing 

abunclan t remains of diatoms and other 

minute forms of sea life that is commonly 

lmown as dia to maceo us shale. This formation is mapped and discussed in this 

report as theMaricopashale.1 T}lelower 

pa:rt of this shale is the equivalent of the 

shale in the Monterey group, commonly 

lmown as "Monterey" shale, but the 

upper part, which is composed of coarse 

. granitic gravel and diatomaceous shale, 

is eq,uivalent to the Santa Margarita formation. At the type locality the thickness of the }.faricopa shale exposed is 

4,800 feet. 

In a small area in the north slope of the 

San Emigdio M:oun tains occurs a coarse 

arkosic sandstone containing a Santa 

:Margarita fauna. This sandstone rests 

unconformably on the Vaquero~ formation and on the Tejon, but it nowhere 

rests on the diatomaceous shale formil).g 

the lower part of the Maricopa shale. 

Because of its fossils and stratigraphic 

position this sandstone is correlated with 

the Santa }.1argarita formation and is 

here designated Santa }.1argarita. 

t!~frua~i~~p~~~s I :':.:f)~.:i!LZ·f~.i::·i/~{. (RecentendP/eJstocene) ·.~~:·:~:·,:::·.;·.-=~·.~·:::·. 

Pa'o1E;~;;;z) :~~I:~~ I ···•·;:::;::;:-:;::;:::: 

Maricopa shale 

(middle M1'ocene) 

Vaqueros formation 

(lower Miocene; f'orcon· veniencein mapping some 0/i'gocene ia '" - eluded et bese) 

Tejon formation 

(Eocene) 

Basement complex 

: -··················"· 

! 

VERTICAL SCALE 

McKittrick 

group 

In Sen Emigd/o M9unteins enarko.s1~ sandstone con taming Santa Msrgenta 

?%~fa M~ ~~f{;.f[~sfo~';{,e~{b~ rests unconlormably on tile Veq1.1eros end Tejon rormetions 

Monterey 

group 

o.___.. _ _._ _ _,__.L.-_s;_,,oo....:.o_..L.,__....._---~._-.~...~~o:::;,ooo FEET 

FIGURE 2.-Gcneralizod ·columnar section of the rocks in the Sunsot-'M:idway oil 

field and in the north flank of the San Emigdio Moun~ains. Position of oilbearing beds indicated by solid black. 

The }.faricopa shale and the Santa }.fargarita 

formation in the San Emigdio }.1ountains are 

overlain 1incon~ormably by the McKittrick 

·group, which is composed of poorly consoli1 A redefinition or tho nnmo ns used in U. S. Gcol. Survey Bull. 621, 

o.s explained 01~ pages 27-28 or tltis report. 

upper Miocene and Pliocene (~)age. The upper 

formation comprises beds that were deposited 

in brackish or fresh water lakes, or subaerially, 

and is the ~quivalent of the Paso Robles 

("Tulare") ·formation, of Pliocene and Pleistocene ( ~) age. The McKittrick group is at 
22 ·. THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

least 5,400 feet thick in the Sunset-Midway j 

~fi~. -

The McKittrick group is o~erlain by poorly 

consolidated. sand, grav.el, and clay that form 

the ~ece:Jft alluvium filling the valleys and the 

terrace deposits. This material is not essentially different from that embraced in the upper 

part of the McKittrick, and an exact separation of the two terranes can not be made. 

PRE-TERTIARY ROCKS. 

CRYSTALLINE ROCKS. 

GENERAL CHARACTE'R. 

The granitoid rocks that crop out in the 

central part of the San Emigdio Mountains 

form part of the granitic batholith that was intruded in late Mesozoic time into the region 

now occupied by the Sierra Nevada~ In· the 

area now occupied by the San Emigdio and 

Tehachapi Mountains but little trace remains of 

the rocks into which this granitic mass was 

intruded, and, except for a few small masses of 

dark slate and of amphibolitic schist, the rocks· 

that crop out within a mile or so of the contact 

with the Tertiary rocks are all granitoid. 

As a whole the granitoid rocks are rather 

basic and may well be described as granodiorite. Their character is, however, by no means 

constant and ranges from that of a rock containing abundant quartz to that of orie containing 75 or 80 per cent of amphibole or pyroxene. 

A. rock made up largely of coarse crystals of 

hornblende forms a considerable. part of the 

north flank of the Tehachapi_ Mountains east of 

Tejon Pass, whereas quartz-bearing porphy_ 

. ritic granite forms the north slope of the ridge 

extending northwestward from San Emigdio 

Mountain. 

West of the area shown on the map (Pl. II) 

the granitic rocks are covered by the Tertiary 

sedimentary formations, and except for two 

fault blocks, one about 5 miles south of the 

south edge of the area mapped and the other 

just west of the crest of the Temblor Range, 

west of the Midway field, granitic rocks do not 

appear at the surface between the San Emigdio 

Mountains and the San Jose Range, a ·distance 

of ·almost 50 miles. Thus those who postulate 

a single period of granitic intrusion in California 

and assign a like age to the granite of the 

Sierra· Nevada and that of the Coast Ranges 

must rest their case upon evidence other than 

continuity of outcrop. 

ECONOMIC· IMPORTANCE. 

The crystalline rocks have no bearing upon· 

the occurrence of oil, serving neither as an 

original source of petroleum nor as a reservoir 

in which it might collect, but they contain 

deposits of several metallic minerals, notably 

stibnite. The chief deposit of stibnite occurs 

on the east slope of Antimony Peak, where 

veins containing this mineral cut the granite 

and may be traced for a distance of over 4,000 

feet. A smaller deposit was noted in sec. 7, 

T. 9 N., R. 20 W., where quartz veins containing stibnite cut an amphibolite schist. 

At the locality on .Antimony Peak considerable 

work was done about 25 years ago and a 

reduction plant was erected on San Emigdio 

Creek, but this has long since been abandoned 

and the mine was completely caved when 

visited in 1912. It is reported that in 1915, 

.when· the price of antimony rose greatly, the 

mine was reopened and considerable work was 

done. 

LATE MESOZOIC R9CKS. 

In thesouth end of San Joaquin Valley the 

late Mesozoic record is scant, and much of the ' 

history of this time can only be inferred from 

fragmentary evidence, for the Franciscan 

(Jurassic ~), . ~oxville (Lower Cretaceous), 

and Chico (Upper Cretaceous) rocks that form 

so large a part of the Coast Ranges to the north 

are nowhere exposed. . Rocks of the Francis~ 

can and Knoxville formations p~obably do not 

occur in the region mapped. During the later 

part and possibly during most of the time 

during which tb,ese formations were being deposited in the region to the north the ·.region 

shown on the map (Pl. II) was elevated above .. 

the sea and subjected to erosion. It seems 

probable, however, that Upper Cretaceous 

(Chico) sediments were deposited both in the 

Sunset-Midway region and in the San Emigdio 

Mountains, for rocks of that age are now exposed in the Temblor Range, only a few miles 

north of the area shown on the geologic map. 

In the San Emigdio Mountains also ·the basal 

Eocene beds which rest upon the granite contain pebble~ of unmet~m.orphosed sandstone 

that were evidently derived from beds at one 

time exposed in the central part of the mountains, for it is from that area that the sediments 

composing the Eocene beds were derived. 

Therefore Cretaceous rocks, similar to those 

now exposed in the northern part of the 
.·, 

THE 'SUNSET-MIDWA~ OIL FIELD, CALIF.-PART I. ·23 

Temblor Range, probably underlie a consid- mountains from a point s· miles east of Tejon 

erable part of the Sunset-Midway region b!3- Pass-or Caiiada de las U.vas, as it was known 

neath the cov·er of Tertiary formations. to the early inhabitants of this region-to 

TERTIARY sYSTEM. Santiago Creek, a distance of about 30 miles. ~ast of San Emigdio Creek the Tejon is steeply 

TEJON FORMATION (EOCENE). tilted and crops out in a belt that is usually 

GENERAL CHARACTER -AND STRATIGRAPHIC not more than a mile across; but west of th~t 

RELATIONS. creek, where the formation is exposed in· the 

The oldest unmetamorphosed sedpnentary. trough of th.e Devils Kitchen syncline, the belt 

beds now exposed in the region are those e~- broadens and .i~ places is as much as 3 miles 

braced in the ':rejon formation (Eocene)~ This wide. Besides this main belt of outcrop 

formation is composed mainly of :fine-grained patches of the Tejon isolated by erosion fron1 

arkosic sandstone and sandy shale with a the m~in body of the formation rest upon the 

small amount of· conglomerate,' and was de- granitic rock _in the central part of the range 

posited in marine waters upon a very uneven and are especially numerous about 3 miles east 

surface of granitic rock. It is overlain uncon- of Tejon Pass. Only two suoh remnants of the 

formably by the rocks here mapped as Va- basal Tejon were found within .the area shown 

queros. Its relation to the ·overlying rocks is, on the map, on the north slope of Antimony. 

however, not .very well shown, for nowhere Peak; but doubtless a careful search would 

within the area exaniined do the two formations reveal others stranded upon the granitic rocks 

show measurable discordance in angle of dip, in the higher parts_·of the mountains. · 

nor is there any marked lithologic change .in It is thus evident that the basin in which th~ · 

passing from one to the other. It seems e.vi- Tejon was laid down extended considerably 

dent, however, that an unconformity exists at southward from the belt of outcrop shown on 

the top of the Tejon in ·this region just as it the map, and the formation may have been dedoes in the northern part· of the Temblor posited over the whole ·of the San EmiO'dio 

Range, noi·th of the limits of the area shown on Mountains and the region to the south asb far 

the geologic map (Pl. II), for the change in as the drainage basins of Sespe and Piru creeks, 

the fauna is too abrupt and complete to be where Eocene beds, practically if not exactly 

explained readily in any other way. More- the equivalent of the Tejon but locally known 

over, the presence of an unconformity at the as the Topatopa formation, are exposed. It 

top of the Tejon is suggested by the variation seems more probable, however, that parts of the · 

in the_ thickness of that form~tion, although San Emigdio Mountains were above the sea 

in this region, where both the thickness ·and . thro~ghout Eocene time, because a la~ge part 

lithology of the Tertiary formations varies so of the material of whioh the Tejon is comgreatly, such .variation can not be. accepted as. posed was derived from the granitic rocks 

positive proof of a break in sedimentation. forming these mountains, and .although the 

The Tejon · increases . gra.dually in thickness Topatopa · · an.d the ~ejon were deposited 

westward from Salt Creek and reaches its synchronously, it is not yet established that 

max:imum thickness near San EmibO'dio Creek they were laid down in the sffi;ue .basin. . \ ' where shales unlike anything in the ,Salt The lower part of the Tejon is usually coarse 

Creek section constitute the topmost part of grained, being especially so east of San· Emigdio 

the formation exposed. It may be that these Creek and also west Qf that creek on the north 

shales are but a lithologic variation of the side of the granite that i.s exposed north of'the 

beds at the top of the formation on. Salt axis of the Devils Kitchen syn~iine. ·. East of 

Creek, but as ~1early as may be judged from San Emigdio Creek the lower 75 to 200 feet of 

the somewha~ unsatisfactory field evidence the the Tejon is ooniposed of massive s~ndstone alten1ate hypothesis-that they are the equj.va- formed largely of granitic debris and ·containlent of beds which are not exposed in the Salt ing many fragments 1 or 2 inches in diameter. 

Creek area and therefore that an unconformity These beds are well exposed on the east side of 

marks the top of t~e Tejon-s~ems more prob- Pleito Creek where they weathm· to prominent 

able. This shale is described on pages 24.:...25. rugged outcrops. At Los Lobos Creek, on the 

north side of the- granite exposed north of the 

DISTRIBUTION AND LITHOLOGY. D axis of the evils Kitchen syncline, th6 lower 

The Tejon forn1ation crops out in the north 20q feet of the Tejon is composed of fossiliferous 

flanks of the Tehachapi and San Emigdio shaly sandstone interstratified with massi.v:} 
24 THE SUNSET-MIDWAY OIL FIELD,' CALIF.-PART I. 

sandstone filled with boulders of basic igneous 

rock derived from the crystalline mass upon 

which they rest. These boulders are only moderately well rounded and vary considerably in 

size, the largest being about 2 feet in diameter. 

Exposures of these basal beds on Los Lo bos 

Creek are shown in Plate VII. _ 

'The· middle part of the Tejon is composed 

mainly of shalysandstone and shale that weather. 

easily, forming a fairly deep yellowish-brown soil. 

The shaly beds weather so much more easily 

than the sandy beds that the section there, if 

judged by.weathered outcrops, appears much 

n1ore sandy than it really is. In places the 

fine-grained beds o011tain lenses of conglomerate 

5 or 10 feet thick, and weathering brings into 

slight relief· indurated calcareous beds, usually 

somewhat coarser than the bed in this part of 

the formation and containing fossils; but on 

the whole the middle part of the Tejon east 

~of San Emigdio Creek presents no striking 

lithologio divisions, and the tabulated section 

of the formation as exposed near Pleito Creek 

give~ below presents a very fair description of 

the formation throughout this part of the region. 

West of San Emigdio Creek and south of the 

isolated body of granitio rocks exposed there 

the Tejon is formed almost wholly of finegrained micaceous thin-bedded or :flaggy sandstone and dark clay shale. These ·beds were 

e-vidently deposited in shallow water, for. they 

show ripple marks and contain a little carbonaceous matter and impressions of terrestrial vegetation~ · 

Filled with fossil marine shells. :Mapped as 

base of Miocene. 

2. Sandstone; fine grained, shaly, probably gray 

when fresh but weathers easily to brownish 

Feet. 

sandy soil. Contains a few calcareous layers 

carrying marine fossils.. . . . . . . . . . . . . . . . . . . . . . 1, 200 

3. Conglomerate; well-rounded fragments, mainly 

quartzite and granitic rocks, filled with 

marine fossils .............................. . 

4. Sandstone; much like bed 2 above but includes 

numerous dark..:brown concretions hardened 

by lime and iron and containing fossil shells. 

10 

A few pebbles o~ granitic rocks on surface .... 1, 890 

5. Sandstone; somewhat more indurated and slightly coarser grained than that ~n overlying beds; 

weathers to prominent outcrops.............. 100 

6. Sandstone; very :fine, even grained but less shaly 

than bed 8 below. .. .. .. .. .. .. .. .. .. .. .. .. .. 350 

7. Sandstone; slightly coarser than underlying bed 

8 and contains a few well-rounded quartzitic 

cobbles having. a maximum diameter of 5 

inches .............. .'. . . . . . . . . . . . . . . . . . . . . . 100 

8. Sandstone; very fiJ?-e, even grained and shaly; 

weathers to minute light-brown angular fragments; contains many impressions of terrestrial vegetation; exposures poor, soil deep... 300 

9. Sandstone; coarse grained, containing many 

fragments as large as No. 6 shot and a few 

granitic cobbles a few inches in diameter. 

Material evident1y derived from granitic 

rocks of central part of San Emigdio Mountains. Weathers to prominent outcrops traceable for several miles. Rests upon crystalline 

rocks ............ ·. . . . . . . . . . . . . . . . . . . . . . . . . . . 250 

4,200 

Between Pleito and San Emigdio creeks the 

uppermost part of' the Tejon is composed of 

shale that varies in color from greenish black 

to chocolate-brown. This shale is thickest on 

San Emigdio Creek. It wedges out rather 

abruptly toward the '"east and was not recognized in the canyon of Pleito Creek. This 

wedging out may be due to the replacement_ 

of the shale by sand, but, as is explained on 

page 23, the writer is inclined to believe that 

the shale is younger than· the uppermost 

Tejon exposed on Salt· Creek and Canada de 

las Uvas, and that the disappearance of the 

shale. is caused J;>y the unconformable overlapping of the Vaqueros formation. 

The thickness or the Tejon exposed varies 

greatly, probably owing. both to the uneven 

surface upon which the formation was deposited and to the unconformable overlapping 

of the Vaqueros formation. The exposed 

thickness is greatest near Pleito Creek; about 

4 miles east of San Emigdio Canyon, where the 

formation comprises sandstone, shale, and con-· 

glomerate aggregating a thickness of about 

4,300 feet.· The following section was measured near the point where the exposed thickness is greatest .. The recorded thicknesses a~e 

accurate to about 10 per cent. In the first canyon west of Pleito Creek_,_ 

that is, the one draining northward through the 

Section of Tejonjormation on ridge bet'ween Salt and Pleito western part of sec. 34, T. 10 N., R. 21 W.--:-the 

creelcs in sec. 31. T. 10 N., R. 20 W., and sec. 5, T. 9 N., shale is about 75 feet thick. In this vicinity 

R. 

20 

W. Feet. it weathers to a deep, loose soil 'that supports 

1. Sandstone; hard, calcareous, gray when fresh, I little vegetation, or to hill slopes covered with 

w:eathering to dark brown; :fine, even grained, n.ngular shale fragments one-fourth to one,-ha).f , average diameter of grains about 0.2 mil- ' 

1. t th · t · t t inch wide. The shale is distinctly a clay shale 1me ers; wea ers o prommen ou crops .. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE VII 

A. GENERAL VIEW. 

B. DETAIL. 

BASAL PART OF TEJON FORMATIO ON LOS LOBOS CREEK IN FOOTHILLS OF SAN EMIGDIO 

MOUNTAINS. 

Interstratified arkosic sandstone and coarse boulder beds. Note small fault a t base of exposure. 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE Vill 

DEVILS KITCHEN, SAN EMIGDIO CANYON. 

Looking easL across canyon. The sharp peak at the right is Eagle Rest. The massive beds forming Eagle R est are marine Oligocene; shale of the Tejon formation covers the broad slope to the right of this peak. Photograph hy W. C. Meodenhall. 
TERTIARY SYSTEM. 25 

as distinguished from the lighter~colored sandy 

shale in the lower part of the Tejon. Beneath 

this ~hale are fine-grained grayish sandstones 

and shales that closely resemble those of the 

overlying Vaqueros formation, and about the 

only noticeable difference in the.lithology of the 

two formations is the character of the concretions. The concretions in the Tejon are usually regularly for1ned and sm,.oothly rounded, 

looking like large balls or dmnbbells, and when 

broken or even when considerably weathered 

they show a shelly or concentric structure. On 

~the other hand, most of those of tl1e Vaqueros 

formation are irregular lentieular n1asses whose 

greatest length. lies parallel to the bedding. In 

the field these concretions· were termed ''con~ 

cretionary layers" to distinguish them from 

the n1ore symmetric concretions. common in the 

older formations. 

In the canyon of San Emigdio Creek the shale 

composing the uppennost part of the Tejon is 

best. exposed opposite the mouth of Williams 

Creek. :Most of the Tejon that crops oU:t east 

of the creek,, in the north flank of the Devils 

Kitchen syncline, is composed of sandy shale 

that weathers to chocolate:-brown. This shale 

supports little vegetation other than a few scattered groups of juniper trees. In general aspect 

it resembles the more clayey phases of the later 

Tertiary diatomaceous shale in this reO'ion or 0 

the Kreyenhagen and Moreno shales in the 

Coalinga region.1 

The general lithologic similarity and the like 

stratigraphic relations suggest that this shale 

mri.y be the equivalent of the Kreyenhagen 

shale. No fossils were found in the shale, and 

for the present at leas~ it is considered as part 

of the Tejon. · · 

On Grapevine Canyon (Canada· de las Uvas) 

the Tejon is somewhat broken by faults and the 

lower part is covered by landslides of granite 

debris that have come from the higher parts of 

the range on the south. It is therefore difficult 

to make out the true character ()f the formation 

or . to. determine its thi~lmess \yith accuracy. 

It IS unfortunate that th~s, according to Whitney's description, is the ·type section of the 

!ejo.n;for the formation is apparently thicker, 

1s better exposed, and contains more fossils west 

of this locality, in the vicinity of Pleito Creek. 

1 Anderson, Robert, o.nd Puck, R. 'V., Geology o.nd oil resources of 

tho west border of tho So.n Joaquin Valley north of Coalinga, Calif.: U.s. 

Cool. SurYoy :Pull. 603~ pp. 50, 75, 1915. 

AGE AND CORRELATION. 

The Tejon formation is of Eocene age, as is 

shown by the marine invertebrate fossils that 

occur scattered throughout it. The type section ~f the formation is at Grapevine Canyon, 

or TeJon Pas,s .(Canada de las Uvas of. the early 

explorers.). The geology of this section was 

first studied by Blake, geologist for the Pacific 

Railroad Survey, and the fossils collected by 

him were determined as Eocene by Conrad. 

Lat~r Gabb, paleontologist of the GeoloO'ical 

Survey of California, after a careful stud; of 

the fossils from this .region, referred these beds 

to the Upper Cretaceous. The name Tejon was 

applied by Whitney frmn their occurrence near 

.old For~ Tejon, in Grape~ine Canyon, although 

in the same sentence he says that the beds are 

also typically exposed in the Mount Diablo 

region. More recent studies of the fauna of the 

Tejon have shown that it is properly referable 

to the Eocene and not to the Upper Cretaceous. 

Dickerson 2 has studied the fauna of the 

Tejon in considerable detail and has published 

lists of the species collected by him at the south 

end of San Joaquin Valley from the exposUl'es 

of the Tejon in and east of the cany.on of Salt 

Creek, chiefly from Liveoak, about 3 ~iles east 

of Tejon·.Pass. There the uppermost beds of 

·the Tejon contain an abundance of fossils and 0 ' It was probably from these ·very exposUl'es or 

in float from them that Blake collected the· 

fossils he obtained. 

IMPORTANCE WITH RELATION TO PETROLEUM. 

No evidence of petroleum has beendisc~vered 

in the Tejon formation anywhere in the southern part of San Joaquin Villey. The shale that 

forms the uppermost part of the formation in 

the vicinity of San Emigdio resembles somewhat the more clayey phases of the organically 

formed shales-the diatomaceous shaleswhich are found i.n the productive oil regio~s and in which the oil originated. It is not im:.. 

probable, therefore, that oil may occur in this 

part of the ·formation and that it might concentrate in certain places and form pools of 

commerical. value if the structure were favorable for such ccncentration. The structure 

does not appear to favor concentration, how2 Dickerson, R. E., Stratigraphy and fauna of the Tejon Eocene of 

California: California Univ. Dept. Geology null., vol. 9, pp. 42Q-421, 1!JlG. 
THE SUNSET.:.MIDWAY OIL FIELD, CALIF.-PART I. 

eVier, except in the short anticline that lies between San Emigdio and Pleito creeks . and on 

the north side of the Devils Kitchen syncline. 

The possible occurrence of petroleum here is discussed on page 1 7 0. 

Vaqueros formation.-As explained on page 

21 the term Vaqueros formation is used in tllis 

report to designate a thick succession of sandstone, conglomerate, and shale that was deposited during Oligocene and early Miocene 

~LIGOCENE. AND1 MIOCENE ROCKS. 

NOMENCLATURE. 

time. The lo:wer or Oligocene beds (here for 

convenience included in the Vaqueros) consist 

of marine sandstones containing abundant inRelation of the formations.-In the present 

report .the s.trata of Oligocene and early 

Miocene ages are grouped into formations 

that do not correspond precisely witli· the 

formations that have been described for other 

parts of the Coast Ranges of California. The 

miter believes that the structure and geologic 

vertebrate foss.ils which correspond well with 

the fauna of a part of the "Astoria group"~ 

and with that of the Sobrante sandstone or 

Agasoma zone in Contra Costa County, Calif.2 

These formations are now believed to be Oli-' 

gocene, and this lower part of the Vaqueros 

formation as here mapped is therefore. to be 

considered as of Oligocene age. The upper 

part of the forinadon, to judge both from the 

meager fauna it contains and from its close 

stratigraphic relation to the overlying diatomaceous shale, -is evidently of lower Miocene 

age and to be considered as the equivalent of 

the Vaqueros formati<;>n. .·The writer did not 

have sufficient time to separate the deposits 

into these two parts, for the structure in this 

region is so complicated that it would take detailed stra~igraphic and paleontologic work to 

·make the separation in a satisfactory manner. 

For the present,· therefore, the strata are 

grouped into a single formation, which for convenience is termed the Vaqueros formation, although the Oligocene beds do not properly 

constitute a part of that formatio~. It will 

· history of this· particular region are brought 

out more clearly by this grouping, and was not 

able to devote.suffident time .in ·the field. to the 

study of these strata to permit their se~regation into formations corresponding .precise~y 

to those that may be termed the standard.formations of the Coast Ranges. The relation of 

the formations described in the present paper 

to the formations commonly described in other 

parts of the Coast Ranges is shown in the accompanying table arid is described in the iollowing paragraphs. 

Relation between formations described in the pre.r~ent report . . and in prevw·us reports on this and near-by areas. . 

Present report. Previous reports. 

ci. Paso Robles ("Tu- ~ ;:::l Tula.re formation. lare ") formation. . s 0 .... 5b 0 ....,. 

,.!4 ,.!:4' 

.~ \..)~ 

Etchegoin formation, ·;::.;:l ~ """""" E tchegoin and J aca- """ probably including """ ~ a refJresentative of ~ litos formations. \..) J aca itos formation. \..) 

~ ;:g 

Santa Margarita for- Santa Margarita forn,ui.tion. 

mation. 

Maricopa 

sh~le. ci. 

;:::l Monterey shale, diaAbsent. 0 tomaceous shale. to Salinas shaie. · >. 

<l) 

.... 

<l) 

""" Vaqueros formation, in- ~ 

0 Vaqueros formation. -..; eluding, for conve- """ nience, some Oligocene 

at base. Kreyenhagen shale. 

Tejon formation. Tejon formation .. 

- doubtless be possible, when more detailed 

work is done, to separate the Oligocene beds 

from the ·lower -Miocene beds or Vaqueros 

proper. However, in spite of the fact that the 

conditions governing deposition varied in different parts 'of the south end of San Joaqufu Valley 

d~ring the time these· sediments were being 

laid down, the general relations of the beds indicate that deposition was .fairly constant and 

that such interruptions as occurred were local. 

It seems appropriate, therefore, that the whole 

succession of beds -should be considered as one 

formation. It is probable that in other parts 

of California an equally close relation exists between lower Miocene and Oligocene beds, and 

that in certain areas beds which have been de1 Arnold, Ralph, and Hannibal, Harold, The marine Tertiary stratigraphy of the north Pacific coast of America: Am. Philos. Soc. Proc., 

vol. 52, No. 212, November-December, 1913. 2 Clark, B. L., The occurrence of Oligocene in the Contra Costa Hills of 

middle California: California Univ. Dept. Geology Bull., vol. 9, pp. 

9-21, 1915. 
TERTIARY SYSTEM. 

scribed as part of the Vaqueros formation are in 

reality of Oligocene age. · 

Monterey group.-The Mon~erey group is not 

mapped as such on the geologic map accompanying the present report, although its approximate. boundaries are shown on the :r;nap, 

and the term Monterey is used in places. in 

the text. As the previous usage of the term 

Monterey has not always been uniform it becomes necessary to define the use to which the 

term is put in this report. 

The term Monterey has been used in descriptions of California geology in t-ro distinct ways. 

One group of writers has applied the terms 

"Monterey series," "Monterey group/' "Monterey formation" to a terrane of varied lithology including both coarse material, such as 

sandstone,· gravel, and boulder beds, and fine 

material, ~hiefly diatomaceous shale, that was 

deposited during a period of continuous sedimentation in early Miocene time. Another 

group of writers has sought to restrict· the term 

Monterey to the fine-grained or shaly beds that 

wer~ deposited chiefly during the later part of 

this time; and hence the terms ''Monterey 

. shale" and "Monterey formation" have been 

used to describe the deposits of diatomaceous 

shale that are so abundant in· the southern 

Coast Ranges of California. The coars~-grained 

beds associated with the diatomaceous shale 

have been described· by these writers as 

another formation, usually .call~d the Vaqueros formation. 

It is con'?'enient in de~cribing the geology of 

the southern Coast Ranges of California to 

have definite names by which to designate 

separately the shaly and the sandy beds that 

were deposit~d during thi~ time, for in most 

places· it is possible to .make some sort of a 

separation in the field between the coarse beds 

below and the fine ones above. 

To the writer it· seems evident that in this 

south end of San Joaquin Valley there was no 

considerable interval of er0sion separ~tingo the 

·Monterey into two division~, but rather it appears that there were many local and unrelated 

periods of erosion during one. general period of 

sedimentation. It is thus equally convenient 

and necessary to have some name to apply to 

the beds laid down during the whole of this 

period of. sedimentation as to have two names 

to designate the principal parts separately. 

It is therefore desirable to have three . 

distinct names for use in describing ·the deposits-a name for the group as ·a whole, a 

name for the lower and dominantly coarsegrained part, and a name for the upper and 

dominantly shaly part. The trouble lies in the 

fact that the name Monterey has been used 

for. the group as a whole and also for the shale 

alone. 

A full discussion of the propriety of these 

different usages of the term Monterey wo~ld 

require more space than can be spared in this 

report, but it may be said that the term as 

first used was probably meant to designate 

the larger unit of deposition rather than only 

the subordinate lithologic phase. Certainly it 

was in this broader sense that the term Monterey :first had wide application in geologic 

literature, although both usages are now common among those working in the geology of 

the California Coast Ra~ges. A description of 

the ways in which the term Monterey had been 

used up to 1912 has ·been given by Louderback, i and to his paper the reader is referred 

for a inore detailed discussion of the subject . 

:Monterey has been adopted in the larger or 

group sense by the United States Geological 

Survey. 

In the present report the term wherever · 

employed m the text 0 is therefore' used to 

designate the larger unit, and as here de;fined 

the ¥onterey group includes all the Miocene 

beds older than the Santa Margarita. These 

beds are the equivalent of those that were 

described by. Arnold and J ohnso~ 2 as the 

Vaqueros formation and Monterey shale. As 

thus described the Monterey group corresponds 

to the Vaqueros formation (~xclusive of the 

Oligocen~ beds which f<;>r convenience are here 

included in the Vaqueros) and the lower part 

of the Maricopa shale as shown on the geologic 

map (Pl. II). 

},faricopa 8hale.-In the present report t~1e . 

term 'Maricopa· shale is· used to describe the 

thick mass of ·diatomaceous shale that forms 

the central part of the south end of the Temblor 

Range and crops out in places along tl~e north 

flank of the San Emigclio :Mountains. The 

1 Louderback, G. D., The Monterey series i.n California:· California 

Univ. Dept. Geology Dull., vol. 7, pp. 177-241, 1913. 

s Arnold~ Ralph, and Johnson, .H~ R., Preliminary report on the 

M:cKittrick-Stmsct oil region, Kern and San Luis 0 bispo counties, Calif.: 

U.S. Gcol. Survey Dull. 406,·pp. 42-62, 1910. 
28 THE SuNSET-MIDWAY OIL FIELD, C,A.LIF.-PART I. 

lower part of' this diatomaceous shale is the 

equivalent of the upper part of the Monterey 

group as defined on page 27; but the upper 

part of the shale is equivalent to the Santa 

Margarita formation as developed in ·the 

Salinas Valley. In the preliminary report 

these beds were described as the Monterey 

shale and the Santa Margarita (~) formation. 

Although it is possible along the east flank of 

the Temblor Range and in a ·part of the Pleito 

syncline to separate the shale on a lithologic 

basis into two parts, the upper of which contains more coarse sandy beds and lenses made 

up of granite boulders than the lower part,· 

· the write:r: can not see that there is good evidence for assuming that the line thus drawn is 

the same as the line between the Monterey 

group and the Santa !1argarita formation. 

In·asmuch as the diatomaceous shales are of so 

great importance in the consideration of .the 

· occurrence of oil-they are believed to be the 

·original source of the oil-it seems best to 

consider all the shale as belonging to a single 

formation, especially as the field evidence 

indicates that deposition was probably continuous throughout the time during which 

these beds were laid doWil. 

The name Maricopa was selected for these 

diatomaceous shales from a typic~} section near 

Maricopa, in Sunset Valley, and the name was 

first published in a report by W. A. English/ 

to designate certain strata in Cuyama Valley, 

west of the area describ~d in the present 

report, the strata exposed there being correlated 

with the diatomaceous shale exposed near 

Maricopa. Further field work, however, done 

in the east flank of the Temblor Range and in 

Cholame Valley during 1915 and 1916, in 

carrying on the investigations of the petroleum 

resources of California, has brought out the 

fact that the upper part of the typical Mari<?opa 

sht~1e in the Sunset region is . composed of 

younger beds than any of those that were 

termed Maricopa shale in, the Cuyama Valley, 

being in fact equivalent to the Santa Margari.ta 

formation, and the correlation of these beds in 

the Cuyama Valley with the typical Maricop~ 

shale is therefore not correct. In a later 

paper 2 English describes diatomaceous shales 

that form the upper part of the :Monterey 

1 Geology aru:l oil prospects of Cuyama Valley, Calif.: U. S. Geol. Survey 

Bull. 621, pp. 191-215, 1916. 

2 Geology and oil prospects of thcSalinasValley-Parkfieldarea, Calif.: 

U. S. Gcol. Survey Bull. 691, pp. 228-229, 1918. 

• 

group as the Salinas·· shale, and the shale 

termed Maricopa shale in the report on Cuyama 

Valley should properly be called Salinas shale. 

Santa Margarita jo'f"''nation.-In the foothills 

forming the north flank of the San Emigdio 

Mountains are exposed coarse sandston.es that 

contain typical marine invertebrate fossils of 

Santa Margarita age. These beds· are the equivalent in age of the beds forming the upper part 

of the :Maricopa shale in the foothills on the east 

flank of the Temblor Range. They rest unconformably on the Vaqueros and Tejon .formations and are unconformably overlain by the 

Etchegoin formation. Because of their fauna 

and their stratigraphic position they are here 

designated the Santa Margarita formation. 

VAQUJ!;ROS FORMATION (LOWER MIOCENE).3 

GENERAL CHARACTER AND S'.CRATIGR4PmC 

RELATIONS. 

The Vaqueros formation as mapped in this 

area is made ~p in part of beds that were dep.osited in shallow, near-shore marine 'Yater; in 

part of beds that were deposited in, quiet und 

probably deeper m:arine water; and in part of 

coarse beds that were laid down by running 

water. A very considerable part of the coarse 

debris contained in the formation was derived 

from a rugged land mass, composed largely of 

granitic rocks, that lay in the region now occupied by the Tehachapi Mountains and the eastern part of the San. Emigdio Mountains. On 

the flanks of the rugged mountains that occupied this area were deposited the coarse arkosic 

sandstones and the ill-sorted boulder beds that 

now crop out in the foothills 1east of San Emigdio Creek. Farther from the mountains and 

beneath marine waters were laid down the finer 

sedim~nts that now form the sandstones and 

shales which crop out in the western part of the 

San Emigdio Mountains west of Santiago Creek. 

The area in which the Vaqueros formation 

now occurs as shown on the geologic map (Pl. 

II)' is but a small part of the basin in which this 

formation was deposited, for beds of equivalent 

age crop out in much of the southern Coast 

Ranges and also in the western flank of the 

Sierra Nevada, net:,tr the Kern River oil field. 

The area mapped, however, lies. at the outer . 

edge of the basin of deposition, for throughout 

the period during which these sediments were 

a In this report some beds of Oligocene age are for convenience included 

in the Vaqueros formation, as explained on p. 21 • 
TERTIARY SYSTEM. 29 

being deposited a high· mountain barrier must. 

have occupied the region where the Tehachapi 

. Mounto,ins now stand. The eastern part of the 

San Emigdio Mountains was likewise above the 

sen, during ro,ost of the period, as is shown by 

the fact that the volcanic rocks th11t occur 'in 

the upper part of the V o,queros formation in the 

eastern part of the area rest upon the ·granitic 

rocks near the headwaters of Santiago Creek. 

It is interesting to note that the fossiliferous 

marine beds in the lower part 'of the deposits, here for convenience included in the Vaqueros ·formation; now crop out at an altitud~ of 

6,200 feet above sea level, on the north slope of 

the San Emigdio ~1ouri.tains, giving a rough 

meo,sw·e of the amount of vertical movement 

that the region has undergone since early Oligocene time. 

With the underlying Tejon formation the 

Vaquetos is evidently unconformable, although 

the two formatio'ns 11re so ·alike lithologically 

that they can be differentiated only with great 

difficulty. The evidence of unconformity is 

discussed in the section describing the stratigraphic relo,tions of the Tejon. 

With the overlying Maricopa shale the Vaqueros appears to be perfectly conformable, 

and the two formations, grading ·one into the 

the other, are evidently the products of practically uninterrupted sedimentation. 

LITHOLOGY AND DISTRmUTION. 

The Vaqueros formation crops out in an irregulo,r belt several miles wide in the north flanks 

. of the Tehachapi and San Emigdio Mountains 

from the vicinity of the Tejon ranch, 12 miles 

e11st of Tejon Pass, westw11rd t·') and beyond the 

west end of the San Emigdio Mountains. The 

older rocks upon which the formation rests crop 

out e11st of Santiago Creek, but west of that 

creek t~e Vaqueros forms the crest o~ the San 

Emigdio ~1ounto,ins 11nd extends in unbroken 

outcrop down their south flank. On the southwestern flank of the Temblor Range, west of 

the area shown on the· geologic map (Pl. II), 

the upper part of the Vaqueros is exposed. 

The intervening area, in which lies the productive Sunset-Midway oil field, is underlain beneath the younger Tertiary formations by the 

. lower Miocene or Vaqueros beds proper and 

perho,ps also by the Oligocene beds which for 

convenience ar? here included fu the Vaqueros. 

AREA EAST OF SANTIAGO CREEK. 

In the. eastern part of the area mapped the 

deposits here included in the Vaqueros formation may be divided into four lithologic divisions. The lowest of these divisions is characterized by massive arkosic sandstone filled with 

marine Oligocene fossils; the.second division is 

composed of ill-sorted beds of coarse granitic 

conglomerate and sand that were probably in 

large part deposited subaerially; the third division is composed of basaltic and andesi1 ic flows 

and tuffs; and the uppermost division is composed of fine sand and sandy shale in part if not 

wholly of marine origin. 

Near Pleito Creek the lowest division is ab0ut 

750 feet thick and is composed chiefly of massive 

arkosic pebbly sandstone containing numerous 

·highly fossiliferous calcareous beds thai weather 

dark reddish bro\YD. and a few lenses of con- · 

glomerate formed largely of f11irly well rounded . 

pebbles. The massive sandstone that forms 

the characteristic feature of this division 

weathers to long dip slopes barren of veget11tion 

that are a striking feature of the landscape on 

both the east and west sides of Pleito Creek. 

Outcrops of these massive sandstones are shown. 

in Plate VIII. On the whole these sandstones 

closely resemble the underlying :;;andstones of 

the Tejon, and no st.ructural break is apparent 

between them, nor is a distinct litaologic 

change apparent in many places. The basal 

bed as mfLpped is the lowest calcareous sandstone that contains Oligocene fossils. About 

100 feet stratigraphically below this fossiliferous calcareous sandstone Eocene fossils were 

collected. · · The beds lying above the fossiliferous Eocene sandstone and below the lowest bed 

in which Oligocene fossils were collected miglit 

belong equally well with either the Oligocene 

or the Tejon. For the present they are mapped 

with the Tejon. 

· The division next above the massive sandstone is composed mainly of coarse ill-sorted 

conglomerate made up of poorly rounded fragments of granitic and other crystalline rocks 

derived from the complex that forms the higher 

parts of the mountains to the south and east. 

These coarse beds con.tain fragments that differ 

greatly in size, the largest ones seen h~ving a . 

diameter of 5 or 6 feet. With the coarse beds 

are irregular beds of fine arkosic sand which 

.. 

r, • 
30 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

weather so ea.sily that they form a very inconspicuous part of the section, and the conglomererate appears much thicker than it really is. 

The bedding in this part of the section is exceedingly irregular, huge lenses of conglomerate 

more th.an 100 feet thick wedging out within a 

few hundred feet along the strike. 

A notable fef.Lture of this part of the formation is the bright color that it shows locally as 

far .west as Pleito Creek. The color is best 

shown on Tacuya Creek, where the basal sandstone is not prominent and the whole of the 

formation below the basalt and agglomerate is 

composed of ill-sorted gravel, grit, .and sand 

wit:P, a few lenses of clay. These beds weather 

tQ rugged badlands, and the vertical cliffs, 

brightly colored in irregular streaks of various 

shades of red, brown, green, gray, and yellow, 

give a highly fantastic touch to the landscape. The pa~ticular color a b.ed may show 

does not app~ar to bear any definite relation 

. to the lithology of . the bed, except that the 

reddish color is usually of a deeper tone in 

the fine-gramed or clayey beds than in the 

co~rse beds. 

Most of this part of the formation is barren of 

fossils, bet on accoun:t of its general lithologic 

character, ~ts prevailing reddish color, and its 

lack of the marine fossils that are so abundant 

in the underlying beds, this member is believed 

to have been deposited subaerially. However, 

all of it ·can not be considered to have been so 

deposited, nor can the s~e of the boulders alone 

be considered as proof of subaerial deposition, 

for the uppermost beds of this division east of 

Pleito. Creek contain fossiliferous marine sandstones bedded .with conglomerate formed of 

coarse boulders some of which have a diameter 

of 4 feet: Characteristic outcrops of this division near Salt Creek are shown in Plate V.. 

West of Pleito Creek the conglomeratic member of the Vaqueros formation can not be differentiated from the urideriying massive Oligo-

. cene sandstone, and at the Devils Kitchen, on 

the east side of San Emigdip. Creek, the lower 

2,000 feet consists of alternating beds of massive sandstone and conglomerate. composed of 

fairly' well· r·ounded fragments. The following 

roughly estimated section shows the character 

of the formation at the Devils Kitchen. The· 

beds described, which are shown in Plate VIII, 

are on the north limb of the sync~e. 

.Section of Vaqueros formation in the Devils Kitchen. 

Sandstone, massive, gray, of variable grain, containing numerouS conglomerate lc~es formed of 

well-rounded fragments that range from sand 

grains to pebbles with a diameter of 3 or 4 inches. 

Sandstone weathers to bare dip slopes 600 or 700 

feet long near 3txis of eastward-plunging syncline .. 

Sandstone ·and conglomerate, . much like the overlying beds but weather more easily, and on north 

flank of syncline underlie grassy slope ......... . 

Sandstone, massive and shaly, interstratified in beds 

2 or 3_feet thick. Massive beds weather out and 

give corded appearance to the hill slope~ This 

and overlying zone become coarser grained and 

more resiStant to weathering on north slope of 

Eagle Rest ......... : .......................... '. 

Sandstone, massive, with relatively little conglomerate. Thin beds of browniSh calcareous sandstone filled with Oligocene foSsils occur throughout but are especially prominent toward base. 

For convenience inciuded in :Miocene Vaqueros 

formation. This zone, like the overlying zones, 

is coarser grained on the south limb of the syncline 

than on .the north limb. · Rests on dark shale· 

mapped as Tejon .............................. . 

Feet. 

700 

400 

300 

600 

2,,000 

The following section shows the character of 

the Vaqueros formation in the hills· just south 

of the point where Williams Creek enters San 

Emigdio Creek, on the south limb of the Devils 

Kitchen syncline. The uppermost part of the· 

Vaqueros exposed in the· Devils Kitchen syncline on the east side of San Emigdio Creek has 

been eroded ·from this area, and the beds described in the section given below are the 

equiv~lent of the three lower divisions described 

in the tabulated section given above. 

Section of Vaquerosformatio.n on south limb of Devils Kitchen 

syncline, between-two branches of San Emigdio Creek. 

Sandstone and conglomerate; 'sandstone coarse and 

Feet. 

uneven grain, weathers to yellowish-white outcrops.-............ ·.............................. 500 

Sandstone, mass~ve, fine grained, with a small 

amount of conglomerate ...................... :. 250 

Sandstone, fine grained; weathers brownish; contains numerous calcareous beds that weather deep 

red-brown and contain many fossil shells of Oligocene age .................. ~ . . . . . . . . . . . . . . . . . . . . 200 

Shale, dark when fresh; weathers to yellow-brown.. 150 

Sandstone, fine gramed, thin bedded, grayish-brown 

outcrops ..................................... ·. 50 

Sandstone, fine grained; weathers greenish brown; 

concretionary .................. ~ . . . . . . . . . . . . . . . 200 

Sandstone, much like overlying but contains calcareous beds filled with Oligocene fossils. Rests on 

dark clay shale mapped as Tejon~........ . . . . . . 50 

1,400 
TERTIARY SYSTEM. 31 

The third division'of the Vaqueros formation the south limb of the Cie'naga syncline lies 

east of Santiago Creek is composed almost stratigraphically above the horizon mar;ked by 

wholly of tuff and scoriaceous lava. These. a sma~l bed of andesitio agglomerate that crops 

beds yield but little to the agencies of erosion, out in sec. 11, T. 10 N., R. 23 W. 

and their outcrops usually stand out in bold Westward from the vicinity of San Emigdio 

relief from the softer sands and sandy shales. Creek to Santiago Creek the Vaqueros formaEven the massive conglomerates of the under- tion is mainly fine-grained sandstone and sandy 

lying division are 1nuch less resistant and no- shale with relatively little agglomerate, but it 

where weather out so prmuinently. This divi- contains.many higly fossiliferous beds that are 

sionshows a perfect gradation into the underly- indurated by a calcareous oement and weather 

ing division, for between the coarse boulder beds to rather prominent red-brown outcrops. These 

c01nposed of granitic debri~ and the overlying beds are especially prominent between San 

craggy-weathering andesitic agglomerates are Emigdio and Pleitito creeks some 2 to 4 miles 

beds forn1ed largely of fine angular tuff but con- from the edge of the valley, where they weather 

taining also many rounded pebbles of granitic to smoothly rounded hills· markedly in contrast 

rock. The change fron1 a bed composed .wholly to .the massive slabs of .sandstone and conglomof detrital material to one composed wholly of erate that form the Devils Kitchen and to the 

pyroclastic ntaterial is so gradual that it is not badlands carved out of the younger Tertiary 

possible to say just where the predominance of beds that lie closer to the plain. Plate IX, A, 

one type of n1aterial ends and that of the other shows very well the difference in weathering 

begins. These transition beds are well devol- between these beds and the younger Tertiary. 

oped between Salt and Pleito creeks, where they The highly fossiliferous massive calcareous· 

attain. a thickness of about 200 ·feet. Besides sandstones of Oligocene age that are· for. contlus transition from the detrital rocks to the venience here mapped as the basal part of the 

scoriaceous lava, the close relationship between Vaqueros formation east of San Emigdio Creek 

the two parts of the formation is shown by the continue westward in the Devils Kitchen synpresence of tlun beds of sandstone intercalated cline as far as the NE.! sec. 4, T. 9 N., R. 22 W., 

with the basaltic flows. The character of the where they rest upon the Tejon in the vicinity 

igneous rock that constitutes the upper ·part of of the westernmost point where that formation 

this division is described on pages 52-54. is exposed on the south limb of the syncline. 

Overlying the volcanic rocks in the region Westward from this point younger and younger 

east of San Emigdio Creek ·are fine-grained beds of the Vaqueros rest upon the granitic rock 

grayish arkosic sandstone and clayey sands. that until, near the headwaters of Santiago Creek, at 

are little indurated and weather to smoothly the west end of the exposure of granitic rocks, 

.rounded hills which· support .a fair growth of vo~canic rocks equivalent to those that make up 

grass. These beds contain marine fossils, but the third member of the Vaqueros east of. San 

tho forms so far obtained are not very diag- Emigdio Creek are the lowest beds exposed. 

nostlc. It is believed ·that these beds are the Most of the Vaqueros rocks between San Emig-

·oquivalent of the shale that forms the upper dio and Santiago creeks are fine grained, and 

part of the Vaqueros and crop~ out between the even the beds in contact with the granite conheadwaters of Santiago and Bitter creeks and tain but little conglomerate of the type that is 

also in the vicinity of the point where those so characteristic of the formation farther east. 

streams enter San Joaquin Valley, along the The contact between the Tejon and Vaqueros 

southern limb of the Cienaga syncline·and the formations has not been mapped in detail on 

east end of the Pioneer anticline. The main the north flank of the Devils Kitchep syncline, 

reasons for this correlation lie in the fiwts that and, although the beds resting on the granite 

the chocolate-colored shale at the headwaters west of Lo~.Lobos Creek are mapped as Vaqueof Santiago Creek overlies andesitic and basaltic ros, a narrow belt of Tejon may also crop out 

rocks which are the equivalent of those exposed there. 

east of San Emigdio Creek and that the shale The section given on page 32 is shown graph-· 

mapped as the upper part of the Vaqueros on . ically in figure 3. 
32 THE SUNSET-MIDW A:Y OIL F:t:ELD, CALIF .-PART I. 

·Section of Vaqueros formation below the andesitic tuff, on 

. ridge between Salt and Pleito creeks. 

16. Tuff;' coarse craggy-weathering andesitiG tuff 

that forms crest of hill. 

15. Tuff and thin-bedded tuffaceous sandstone, as 

below, containing fragments of granitic rocks, 

some with a diameter of as much as half an 

Feet. 

inch........................................ 140 

14.· Tuffaceous sand and clay, in alternating beds 

that range in tliickness from 6 to 24 inch.es. 

Color gray, in places light grayish green. 

Very arkosic; black mica exceptionally abundant and fresh. Apparently watE(r-laid deposit of pyroclastic material................ 50 

13. Sandstone; grains vary in diameter, tpe largest· 

about size of B shot; with coarse pebbles. A 

few fragments of fossil marine shells, probably of Miocene age ...... ~.................. 16 

5 6 7 

FEET 

4,000 

5. Sandstone; very massive, weathering to dip 

slope and forming steep north side of ridge. 

Well-rounded pebbles ~:~cattered throughout; 

. a few seal-brown calcareous sandstones filled 

Feet. 

with fossils of Oligocene age....... . . . . . . . . . . 260 

4. Sandstone, massive, arkosic, containing poorly 

consolidated conglomerate lenses and scattered pebbles. Near center are two gritty 

calcareous sandstones 8 to 12 inches thick 

containing Oligocene fossils................. 125 

3. Sandstone, conglomerate, and clay shale intermingled; colored irregularly red and gray, 

the color varying along strike; clay beds usually more reddish than coarser ones. Pebbles in lower part well rounded and usually 

less than 4 inches in diameter. Upper part 

contains irregular fragments a foot or so in 

maximum diameter....... . . . . . . . . . . . . . . . . . . . 225 

8 

14 IS 16 

IZ13~ 

"\: ' . 11);1~ : • 

tO~:il: ,.--------''--------i;·:' 

FEET 

4,500 

4,000 

s ... oo_ . ..L.........Jo....-L..-L--lo ______ s.l.o_o ----_...Jl,OOO .FEET 

FIGURE 3.~Section of Vaqueros formation below the Tertiary volcanic rxks as exposed on divide between Salt and Pleito creeks. 

Numbers correspond to those in section given in the text.' 

12. 

11. 

10. 

Conglomerate; fragments of acidic granite as 

much as 4 feet in diameter, in sandy matrix~ 

locally colored red ........................• 

Sandstone, as above but lacks reddish color; 

contains fosails, probably of Miocene age .... 

Sandstone, arkosic, average grain about size of 

No. 8 shot, locally colored red, filled with 

fragments of fossil shells, probably of Miocene 

age ....................................... . 

9. Conglomerate, coarse and ill sorted; contains 

rocks of varied type-acidic and basic granitic 

rocks, limestone, quartzite, and volcanic 

rock~. Upper 50 feet alternating beds of fine 

12 

15 

9 

2. Sa~dstone, yellowish gray when 'weathered, 

grain about like underlying bed. A few thin 

calcareous beds in lower half containing Oligocene fossils. Upper half poorj,y exposed ... 

1. Sandstone, hard, calcareous; gray when fresh; 

weathers to dark brown; fine, even grained; 

average diameter of grain about. 0.2 millimeter. Weathers to prominent outc10ps. 

Filled with fossil marine shells of Oligocene 

age. Rests on fine-grained sandstone mapped 

as Tejon .......... ·." ...................... . 

AREA WEST OF SANTIAGO CREEK. 

125 

15 

2, 807. 

· sand~to:o.e and gravel containing b,oulders of 

acidic granite, the larges.t 5 feet in. diameter. 

Whole zone colored reddish, but intensity of 

color not consta~t .......................... 1,·l30 

8. Gravel, sand,' and clay; grade into overlying 

West of Santiago Creek the base of the beds 

here included in the Vaqueros formation is not 

exposed, but from the lowest bed which crops 

out along the axis of the anticline that extends 

through sees. 9 and 10, T. 10 N., R. 23 W., to the 

·coarse graveL ................. ·_ .... · ..... ~ . . . . 290 

7. Sandstone; intermingled massive pebbly sandstone as below and soft reddish sandstone and 

·gravel as ·above ........................... . 

6. Conglomerate and massive sandstone; sandstone as below: conglomerate of well-rounded·.· 

pebbles ftS much as 8 inches in diameter ..... 

80 base of the Maricopa shale there is at least 3, 700 

feet of sandstone and shale. The Vaqueros 

formation here is divisible into two main parts. 

315 The lower part is at least 2, 700 feet thick and 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE IX 

A. OUTER FOOTHILLS EAST OF SAN EMIGDIO CREEK. 

The smoothly rounded hills to the right are carved in the upper part of the Vaqueros formation; badlands at the left in later Tertiary gravels. 

B . FOOTHILLS ON NORTH SLOPE OF SAN EMIGDIO MOUNTAINS. 

Looking northeast across Pleito Creek from divide between Pleito and San Emigdio creeks about 2 miles north of Antimony Peak. The hills in the foreground are carved in the Tejon 

formation. The sharp ridge on the right in the distance is formed of Tertiary volcanic rocks lying in the Vaqueros formation . 

,,, z {fl I ""'J 

0 ~- , , r1 . z ... J ::.• 

., r·- :;<J z ·~·. I I -_:j Sl ; .- \!1 - -,:;:> (1 ~ (1 l : .:;) 

C> - .., .-·} . , 

. 

r 

~. 

~ :,. 
U, S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE X 

A. OUTCROP OF DIATOMACEOUS MARICOPA SHALE IN PLEITO HILLS. 

This shale is of the more thinly laminated type. Photograph by G. C. Gester. 

B. UNCONFORMITY BETWEEN DIATOMACEOUS MARICOPA SHALE AND CLAY SHALE OF ETCHEGOIN FORMATION 

IN SAN EMIGDIO REGION. 

Looking west across Muddy Creek. The bedding of the diatomaceous shale is indicated by the hard calcareous layers. The bedding of 

tho clay shale is practically parallel with the contact, which is shown by the sharp change in color. 
TERTIARY SYSTEM. 33 

is composed of massive arkosic, somewhat and Santiago' creeks and near the mouths of 

concretionary gray sandstone that weathers these creeks, on the south flank of the Cienaga 

to dark-brown outcrops. The upper part is . syncline. Most of this division is compo~ed of 

about 1,000 feet thick and is formed largely of thin-bedded clay shale that is almost black 

dark carbonaceous and 'in part diatomaceous when fresh but weathers quickly to a chocolate 

shale that contains many thin beds of iron..; color or even to a grayish white. The shale is 

gray sandstone and dark calcareous layers usually somewhat sandy and in a measure 

which weather light yellow. The shale is resembles· the dark shale that occurs near the 

almost black when fresh but usually weathers top of the Tejon on San·Emigdio Creek. Interto a dark chocolate color or even grayish white, stratified with the shale are irregular or lentic- · 

approaching in appearance the weathered ular beds of fine sandstone a few inches thick 

outcrops of the overlying Maricopa shale. and also thin beds of calcareous sandstone that 

The lower sandy portion of the Vaqueros weathers reddish brown. Most of these cal carecrops out in the central par:t ofT. 10 N., R. 23 ous layers are filled with irregular bits of gray 

W., and forms a belt of fairly rugged hills shaie which give a mottled or blotchy appearwhich trend westward through sees. 10, 9, 8, ance to the.rock or which weather out and form 

15, 16, and 17 of that township. It is excep- a minutely cavernous surface on the outcrop; 

tionally well exposed on Bitter Creek near the In places sandstone forms 50 per cent of this 

east line of sec. 8. Massive iron-gray fine- division; but usually not over 20 per cent. 

grained arkosic sandstone that weathers to Part of the shale that forms the upper cliviirregular brownish outcrops forms the n1ost sion of the Vaqueros formation here evidently 

prominent part of the formatio~ here, but contains a large amount of diatom remains, 

bedded with this sandstone are shaly sandstone like the overlying Maricopa shale, and it is 

and clay shale. The shale is precisely like that possible that a large part of the dark carbonawhich forms the upper part of the formation ceous shale at one tiine.contained the remains 

in this part of the region. It is black when of these minute marine plants, although under 

fresh but weathers to .a dark chocolate color, the microscope no trace of them can now ~e 

is sandy, and occurs in very irregular lenses. seen. · Their absence now can not be taken to 

This m.L"Ced succession· of massive' sandston·e and mean that these organisms may not originally 

carbonaceous shale is ex cell en tly exposed in have' been contained in the. shale, for the · 

the canyon of Bitter Creek in sees. 1 i and 20, siliceous skeletons, which are the only. traces 

T. 10 N., R. 23 W., where the lenticular charac- of these plants that are now found in the truly 

ter of the beds is well sho·wn. In one place diatomaceous shales, are so delicate .that they 

in the wall of the canyon a bed of sandstone would . have been dissolved readily in the 

·2! feet thick wedges out within a distance of organic acids that must have been formed in 

10 feet along the strike. The lenticularity the decay of the coarser vegetable matter. that 

of the larger bodies of sand is of necessity not furnished the carbonaceous matter with which 

so clearly shown in the outcrops as that of the shale is now filled. The ·shales contain 

these small lenses, yet in relation to their large quantities of alkaline salts, and although 

thickness the large bodies of sand are no more small springs are numerous in the deep canyons 

continuous· than the small ones. On the whole near the San Andreas .fault, all furnish water 

this lower part of the Vaqueros formation so charged with mineral salts as to be valueless. 

becon1es gradually more shaly toward the top, The upper division of the Vaqueros is poorly 

grading into the overlying shaly division of the exposed along the south flank of the Cienaga 

formation. Fossils occur sparingly throughout syncline, but the beds here appear to be slightly 

the lower division and were found most abun- more sandy than they are on upper Santiago 

daritly near the top of it, where they occur' in Creek. They seemingiy grade upward into the 

irregular light-gray sandy limestones a few overlying Maricopa shale, the line of separation 

inches thick. The species found are not, how- having been drawn in sees. 3 and 4, T. 10 N., 

ever, very characteristic of the lower Miocene R. 23 W., at the top of a sandy. zone containing 

but have a fairly long range. fragments of pectens and stained slight{y redThe upper shaly division of the formation is dish. Above this zone the beds are more 

best exposed between the headwaters of Bitter markedly shaly. 

109288°--19----3 
34 · ·THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART. I. 

AREA ALONG PIONEER ANTICLINE; is not. exposed here, for the beds are faulted Up 

. The Vaqueros formation as exposed along the against the overlying Maricopa shale. The 

Pioneer anticline east-of Cienaga Canyon is com-, low:er 1,000 feet ?f the formation consist~ 

posed of rather shaly s~ndstone and dark clay mamly of fine-gramed sa~dstone and shaly 

shale that are the equivalent of the upper or sa~df:?tone that we.ather easllY: t.o. a be!t of low 

shaly division of -the formation as exposed rehef. Above this lo.wer divisiOn Is about 

south of the· Cienaga syncline. The massive 2,300 feet of soft greenish-gray sandstone, that 

sandstones characteristic of the lower part of ~eathers greenis~ brown, with. many beds of 

the formation do not crop out here, .and the mdura.ted .sandst~ne ~ .t? 6 fee.t .thic~. Near 

·beds weather easily to form a belt -of low re- the middle of this divisiOn. are two zones of 

lief, which west of Cienaga Canyon is bounded somewhat c~vernous- weathering indurated 

by ridges formed of the more resistant Maricopa sa~ds~o~~' e~ch about 10~ feet thick. Above 

shale. The Vaqueros formation is much more thiS di:VISlOll IS 700 fe~t of Interstratified poorly 

sandy than the ove:t:"lying Maricopa shale, yet a consohdated fine-grained s.andstone and resis- . 

very large proportion ·of the formation is com- ta~t calcareous sandstone In beds 3 to 10 feet 

posed of carbonaceous and probably. in part thick that weather to prominent reef-like outdiatomaceous shale. It is believed probable crops. These calcareous beds contain abunthat the formation becomes much finer grained dant finely ground shell fra~ments, mainly' 

toward the north and that coarse sandstones oysters, barnacles, and pectens. The rocks of 

are even less ab~dant· in. it where itlie.s ·buried this division become ·finer grained and less calbeneath the yolinger deposits that fill' San Joa- careous to~ard .t~e. top, grading into those of 

. quiri Valley .than .they .are-where it ·crops out the overlymg diVISI~n. .The upper 1,000 feet 

along the Pioneer anticline. The probability or s~ of the formation IS. c~mposed of interthat the rocks of the formation are fuie grained stratified sandstone and dm~om~c.e?us clay 

'where it is covered by_ the more recent deposits shale. .In the lower haJ! of this diVISIOn shale 

is suggested by the fact that they become pro- pre~ommate~ and the ~nterbedded sandstone 

~essively finer grained westward along the IS farrly well m.durated; m the upper half sandnorth flank of the San Emigdio Mountains, and st~ne. ~r~dommates. In ~he upper part of 

. in the Temblor Range west of the area mapped this division the ~andstone IS softer and lighter 

the formation contains a large amount of clay colored than that Ill the lo~er part, and thesha.le 

and diatomaceous shale. The less indurated weathers. almost pure white, In contrast to the 

sandy beds-are ilnpregnated with gypsum that pinkish outcrops of the shale in the lower·half. 

has been COncentrated near the surface by the· IMPORTANCE WITH RELATION TO PETROLEUM. 

upward movement and evaporation of meteoric The shaly beds that constitute the upper part 

water. The deposits of gypsite, as this gyp- of the Vaqueros formation west of Cienaga Cansiferous sandstone is called, are most abundant yon are in part diatomaceous and contain a very 

· east ofCienaga Canyon, and that area· is dotted considerable amount of carbonaceous material. 

with trenches that have.been dug as assessment Shales of this type, especially those that are 

work to hold the land, which has been located formed largely of diatomaceous material, are ' 

under the provisions of the placer-mining law. regarded as the source of petroleum in the oil 

Like· the shalES. near the headwaters of Bitter fields in this part of California, and in places 

Creek,~ the Vaqueros formation here contains in the area shown· on the geologic map 

considerable sulphur, and locally in sees. 27 (Pl. II), notably along the axis of the Pioneer 

and ·28, T. 11 N., R. 23 W., both it and the anticline, the ·Vaqueros formation contains 

overlying gravelly beds, which are probably beds saturated with oil. This part of the 

part of the Paso Robles ("Tulare·") formation, f~rrriation should be critically ex~ined, and 

are heavily impregnated' with sulphur. the character, thickness, and structural relaAREA ABOUT SUNSET CANYON. 

In the vicinity of Sunset Canyon. dark.;. 

colored. sandstones which aggregate .about 

5,000 feet in thickness are mapped as the Vaqueros formation. The base of the formation 

tions of the beds composing it should be determined. These features of the Vaqueros 

appear most favorable for the concentration 

of oil along the Pioneer anticline. 

The. Vaqueros formation differs from the 

overlying ~1aricopa shale, which is probably 
· TERTIARY SYSTEM. -35 

the source of most of the oil in the Sunset- . conditions as revealed by the· well. r¢cords 

Midway field, in that it contairis a very con- shows that the Etchegoin was depos~ted)n f.i, 

siderable amount of sandstone interstratified sea that was transgressing westward ov:er the 

with the shale. These sandy beds would Temblor Range, and in consequence the lower 

probably serve as reservoirs in which much of beds of' the Etchegoin wedge· out in that ·directhe oil that originated in ·the shale would· tion. This rel~tion is· showii ·in the· ·geologic 

collect in places where the structure -favored sections · of :Maricopa · Flat. (Pis; . · XX:VIII:-

its concentration and retention. The Madcopa XXXI). · ·· ... ·l · · . ·r .. ~ · • · 

shale contains relatively little sandstone, and. · Sputheast of the ·town of McKittrick, at.· the 

the porous beds that serve as the reservoirs· north end of the ·area ·shown·, on. the tgeolog'ic 

in which oil has collecte·d· are chiefly those that map ,(Pl. II), the Maricopa·l.shale,·is .. overlain 

rest unconformably upon the shale.· This unconformably by a fine-gi·ained grayish or 

difference in the abundance and position of the browni~h ·arkosic sands·ttrfie .. w~th ·beds . and 

sandy beds acting as reservoirs for oil is· of lenses of coarse sand and·pebbly layers,; mapped 

considerable importance, for within· the forma-. as the Etchegoin .formation.I;.'.A-t ·the west end 

tion in which the oil originated the conditions: of the prominent-I,210-foot' hill- in· the NE. 1 

favor the formation of a number of relativeiy · sec. 29, T. 30 S., R. 22 E.·, just east of the main 

small, discontinuouspools, whereas in the b~ds wag~n road betw~en McKittrick .and Midway, 

unconfoi~mably overlying that. formation the these beds 'contain abun'dant specimens of 

conditions. favor the ·formation of a much Pecten eldredgei. The relation of the Etche-· 

more widespread ·and probably much· richer goin here to the underlying. Maricopa shale has 

pool. . been· described by Arnold and Johnson. 2 

Within the main part of the Su.nset-Midway· Less than one-fourth mile due south of the Dabney 

field, in which oil is obtained from the beds (now the Providence) headquarters, and just east of th~ 

ovei-lying the Maricopa shale, the Vaqueros Midway road, is an isolated hill of grayish sandstone which 

formation is far to.o deeply buried to be appears to be a closely appressed syncline of McKittrick 

reached by the drill, and it may :be disregarded formation [Etchegoin formation ·of McKittrick· group folded into the underlying Santa Margarita (?) [Maricopa 

as a prospective source of petroleum. shale]. Immediately south of this hill arid parallel to it 

MAIUCOPA SHALE (MIDDLE MIOCENE). is a email lens of fine-grained brownish sandstone about 

.18 feet thick, which is· apparently · int~rbedded in the 

GENERAL CKARACTER AND STRATIGRAPmO 

RELAT~ONS. 

The Maricopa shale is composed mainly of 

'thin-bedded siliceous, diatomaceous shale co·ntaining numerous th:in calcareous htyers and 

in the lower part a :relatively small amount of 

arkosic sandstone, but in ·the uppe:t; part 

numerous lenses of arkosic sandstone and 

boulder beds. It is typically developed in the 

gulch that drains northward through s~cs. 

I3· and 24, T. II. N., R .. 24 W., where the 

exposed thickness is about 4,800 feet. The 

shale rests conformably upon the Vaqueros 

formation and is overlain unconformably by 

the 'Etchegoin formation. 1 Good evidence 

of the relation of the Maricopa shale to the 

Etchegoin is difficult to obtain from the 

outcrops, for in most of the foothill belt .west 

of the Midway field the shale-pebble beds of the 

Paso Robles ("Tulare"). formation overlap 

the Etchegoin and rest directly upon the 

Maricopa. shale. A study of • the undergroU:nd 

1 As treated in this report tho Etchogoin formation probably includes 

a roprosontatlvo of tho Jacalitos formation ut tho base. 

vertical shale but shows at one place t~at it has been 

either pushed or sifted into fractures which cut across the 

bedding of the inclosing sh~e. The lens contains small 

shale inclusions. It has the peculiar oblique and more or 

less angular' jointing common to sandstone dikes and 

shows on the weathered surface a semiconcretionary 

structure.. If this small area is a sand-filled fracture; the 

source of. the material is obscure. The sandstone is well 

impregnated ~th oil. Qne-half rrule east of· here and 

north of the axis ·are similar masses of sandstone, but 

their relation to. the· shale is much clearer: At this 

point the ·anticline is . overturned toward the northeast so that the sandstone, which is roughly parallel tO 

the bedding of the shales, dips very. steeply southwest. 

Its contact with the shal~s, especiallyon the south, is.very · 

irregular and indicates that the surface of the shales must 

have been pitted and honeycombed before· the sands 

accumulated. Irregular masses and lenses of shale within 

the sand itself are harder to explain but may be fragments 

fallen from an oyerhanging bluff of shale during deposition of the. sand upon' a weather-beaten and precipitous 

.rocky shore. The presence of an irregular scattering 

conglomerate of dark porphyry, schist, quartz, and granite 

pebbles at the base of the sandstone further emphasizes 

the likelihood of such an origin. Above the sandstones 

2 Arnold, Ralph, and Johnson, H. R., Preliminary report on the 

McKittrick-Sunset oil region, Calif.: U.S. Geol. Survey Bull. 406, p. 68, 1910. .• 
36 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

(to t~e northeast) are confo~able beds of rather s~ft formations appear rather as diatomaceous 

. gr~emsh to cream-colored argillac~o~ shal~s of McKit- clay shales than as clayey diatomaceous detnck [Paso Robles] age, and hence It Is practically assured •t Th f t th t th · h 

that the sandstones are the basal beds of·. the post-Santa , posi. s. e ~c s a ey cont~In so m~c 

Margarita(?) [Maricopa shale] formation. They continue detntal maten~l and that coarse beds whiCh 

to the southeast1along the flank of the fold for nearly 2 miles dearly were deposited in the littoral zone 

and form an important oil-bearing bed. appear at so many horizons show that these 

. The unconformity between the Etch ego in and deposits of diatomaceous. material can not be 

the lower part of the Maricopa shale is excel- considered deep-sea deposits .. 

lently well shown in the foothills of the .San Recently Branner 1 has suggested an inEmigdio Mountains near Muddy Creek. Plate genious hypothesis to acconnt for the occurX, B, shows a view ~f the unconformity in that renee of these deposits. After pointing out 

locality. that diatoms flourish in the colder waters of the 

The unconformable relation existing in the ocean, he says: 

San Emigdio Mountains between the Santa As these organisms perish their siliceous skeletal re-

. Margarita formation and the overlying Etche- mains sink slowly to the bottom, especially in those places 

goin formation is discussed in the section deal- where the currents are not strong enough to sweep them 

ing with the Santa Margarita formation (p. 42). along. In this connection.· attention is directed to the 

geography of the coast of California during the geologic 

CONDITIONS GOVERNING DEPOSITION. period when our greatest deposits of diatomaceous shales 

were being laid down. The geology of California suggests 

The conditions under which the Maricopa that the region of the present Coast Ranges was an archi,. 

shale was deposited are not ,thoroughly under- pelago, separating the sea that filled the great valley 'on 

stood. Fine shales composed so largely of the the east from the open ocean on the west, The marine · · f d' t t t ·11 · · currents that flowed southward from Alaska brought down 

remains o. Ia oms are no a. a COffiffiO:J?. m ·great quantities of marine algae, the diatoms floating as 

other parts of the world, and It would appear usual near the surface. Once within the zone of islands . 

. at first sight as if the shale here was deposited these floating materials were probably driven into the 

under special and local conditions But the cul-de-sac at the lower or southetn end of the present San 

M · h 1 l'th 1 · ll ·mil· • h l Joaquin Valley, where the granite mountains of the Sier- ariC?P~ s a e, ?r I _o O~IC~ Y SI ~r s . a e ras bend westward and northwestward. Here the' prevailthat IS ItS strat1graphi~ equivalent, IS Wide- ingwindsoftheregionarefromthenorthduringt~egreater 

spread in the Coast Ranges of California, and, part of the year, and materials carded at or near. the surmoreover shales of like character which· also face of the water could not escape if, as is assumed, the 

have a ;ide distribu.tion occur ~ this same embayment 'vas fairly well closed at the extreme southern . ~ . .' · · end. It is exactly here, at and around at the extreme p:r;~v1nce at still other horizons between ~he top southwestern corner of the San Joaquin Valley, that the 

of the Cretaceous and the .top of the Miocene. deposits of diatom .skeletons are thickest. The total 

It seems unlikely, therefore, that the conditions thickness of these shales is here .more than 5,000 feet. In 

which: governed the deposition of the Maricopa general these ~iatom~ceous ~hales thin out to,vard the 

shale· were very much out of the ordinary. north .and are mconspicuous m the geolo~y north of San 

• _From· t~e fine-graine~ ch~act~r of the shale ~:~:~t to be expected that the theory here put forward 

Jt was evidently deposited m quiet water, not to explain accumulation under the circumstances mennecessarily in deep water, nor. even at any tioned is competent to account for all diatomaceous C:econsiderable distance froni shore but at least posits and much less for all deposits of petroleum. Even 

in a basin into which few large' or torrential in this ins~nce it is evident that all of the diatoms were · . · · · . not ca~ght m the angle of the coast;· some of them were 

streams emptied. . never carried to the landward of the coast archipelago, 

Because· of the fact that the diatomaceous while others escaped to sink farther down the coast. 

deposits which are forming in the present oceans It is believed, however, that the prevailing wiri.dl'l, in 

are found at great depths it has been supposed this instance a~ least, have been an important factor in 

by many that these dep~sits of diatomaceous the accumulation of the oil-bearing deposits . 

. shale were also laid down in very deep water This hypothesis, although at first sight 

and that they are in fact lithified diatom oozes. somewhat surprising, has much to recomIt should be noted, however, that the Maricopa mend it, for it suggests an explanation of the 

shale and indeed all the thick formations of intercalation of fine diatomaceous shale with 

diatomaceous shale in California contain a large coarse sandstones and boulder .beds such· as 

arnount of detrital matter, and, although cer- is characteristic 0 of the upper part of the 

tam 'beds may be made up principally of the· Maricopa shale. As has been shown in the 

remains Of diatoms, When V:iewed as a Whole the 1 Branner, J. C., Geol. Soc. America Bull., vol. 24, pp. 94-95, 1913. 
TERTIARY SYSTEM. 37 

description of the Vaqueros formation, the 

eastern portion of the region shoWn on the 

geologic map (Pl. II) stoo.d at a considerable 

elevation above the sea during Oligocene and 

early Miocene time, while the western portion 

of the San Emigdio Mountains and much if 

not all of the Temblor Range was submerged. 

Owing to a gradual subsidence of the whole 

region, the sea gradually encroached upon the 

land mass in the eastern ·part of the San 

Emigdio Mountains until, at the end of the 

time during which the Vaqueros formation 

was deposited, the sea mu.st.~have submerged 

most of those mouiltains >.and covered the 

s?uth end of the Temblor R~ge to a depth of 

several hundred feet. · This .. subm~rgence continued through much of the Miocene epoch, 

and, although oscillatory movements varied 

the depth of water, it seems probable that for 

no considerable part of this time did this area 

lie close to the margin of the sea. Also it is 

'probable that the land masses in this general 

region had been reduced to relatively low 

relief by the erosion that· they had suffered 

during early Miocene time. Thus relatively 

little detrital matter was brought into the 

basin of deposition and that which was laid 

down was fine grained. 

Toward the end of the period during which 

the. Maricopa shale was deposited there appears to have been a rejuvenation of the 

streams that emptied into the sea in which the 

shale was being laid down. These streams 

carried. into the sea great quantities of sand, 

gravel, and boulders of granitic material, but 

the streams were few, and the time during 

which any one stream carried in coarse material does not seem to have been very Jong. 

In conse'quence the beds of coarse material 

are very lenticular. 

DISTRIBUTION. 

Maricopa shale is the equivalent of the diatomaceous beds mapped as the Monterey 

shale 1 in the Santa Maria region, some 40 

miles. to the west. 

LITHOLOGY. 

GENERAL CHARACTER. 

The Maricopa shale in the central part of 

San Joaquin Valley is regarded as the great 

feeding ground from which was obtained a 

large part of the oil that is now concentrated 

in the foothills at the border of the valley. 

As the oil is believed to have been derived 

from the remains of organisms contained in 

.the shale, the character of the shale beneath 

this. valley filling is an important factor in 

any COJ?.sideration of the petroleum in the 

foothills. There is, of course, no direct evidence regarding the character of the buried 

shale, but from the facts that th~ shale is 

very diatomaceous at its easternmost expo-· 

sure in the San Emjgdio Mountains and that 

the beds of the Monterey group near Kern 

River, although evidently laid down close to 

the eastern margin of. the b~sin of deposition, . 

are largely fine grained, it seems probable' 

that the Maricopa shale maintains in most if 

not all of the south end of the vaHey beneath 

the cover of younger formations the character typical of it in the Temblor Ra:o,ge. 

In the Temblor Range and in the east end 

of the San Emigdio :Mountains the l\1:aricopa 

shale is divided into two parts, the lower part 

composed chiefly of hard siliceous shale containing few coarse sandy lenses, and the uppe.r 

part made up largely of soft, "punky" shale 

with many lenses of coarse gra-vel or boulder 

beds. It must be remembered, however, that 

the separation is based on lithology and the 

line shown on the map does not mark a definite 

stratigraphic horizon. 

L()WER DIVISION. 

AREA IN THE SAN EMIGDIO MOUNTAINS WEST OF SAN 

EMIGDIO CREEK. 

The Maricopa shale within the area mapped 

crops out in a broad belt that occupies the 

higher part of the Temblor Range and extends southeastward to the v:icinity of San- The lithologic character o.f the Maricopa 

tiago Creek. This area is the southeast end shale is relatively constant throughout the 

of the belt of out~rop that occupies much of easte:rn flank of the Temblor Range and the 

the south end of the Temblor Range. The west end of the San Emigdio Mountains. As 

formation continues to the east, underlying· a rule deposits of diatomaceous shale are 

much if not all of the south end of San Joaquin re~arkably constant when compar~d with the 

Valley, and the sandy beds that crop out in other Tertiary formations in this region, and 

the foothills near Kern River ·on the east side although the middle part of tlie ~1aricopa shale. 

· of the valley are in part its equivalent. The JU. S. Gcol. Survey Bull. 322, pp. 33-5:!, 1907. 
.38 THE SUNSET_;MIDWAY OIL FIELD, CALIF.-PART I. 

is inore siliceous, :(iner grained, and thinner · AREA IN THE TEilmLoR RANGE. 

bedded. than either the upper or lower parts, In the higher part of the Temblor Range 

the beds .do not vary greatly along the strike -west of the Sunset and Midway fields the 

in the ·manner so characteristic of the othe:r Maricopa· shale has been flexed into a great 

Tertiary formations in the region. . number of folds. The position of the larger 

The lower part of the Maricopa shale where . folds is shown on the map, but there are a great 

exposed along the Cienaga syncline is com- many small ,wrinkles ·or crumpled areas much 

posed of sandy shale and fine _angular-grained too· small to be mapped, and the structural 

gray sandstone -in alternating beds that details are far more complex than would appear 

range in ·thickness from a few inches to a few from a strict interpretation of the lines ~hat 

·feet. ·Many· of ·the sandstone beds are indu- are shown. The lower part of the Maricopa 

rated by a calcareous c.ement and weather out shale· is exposed iri the southwest corner of 

slightly from the sandy shale,· as likewise do T~ 32 S., R. 23 E., where it consists of internumerous beds of impure limeston:e, or limy bedded massive. sandstone and sandy shale 

. clay ·shale, black when fresh but· ·weathering· that weather to chocolate-colored outcrop~. 

light yellow.· Near the base of the formation as These beds are similar to those that occur near 

mapped on the south limb of the· Cienaga the base of the formation south of Maricopa, 

syncline some of the sandy beds ·are stained and, as in that region, they constitute a gradareddish and a few fragments give an oily odor tion into the· underlying Vaqueros formation. 

·when broken. The main part of the lower division is comThe Maricopa shale is well developed on the ·posed of thin-bedded brittle ·shale, highly 

north limb of the Pioneer anticline south of siliceous, in places really flint or chert. CalPioneer, and the type section of. the· formation careous layers, usually a little more sandy than 

is exposed in the canyon that drains northward the inclosing shale, are abundant, and as they 

through sees. 13 and 24, T. 11 N., R. 24 W., weather a little less easily than the shale they 

past the old Sunset refinery. The following form prominent yellowish out.crops that can be 

section was me~sured in this canycn: traced with the eye for long distances across the 

Section of the Maricopa shale south of Pioneer., 

barren spur ridges on the eastern slope of the 

Temblor Range. At many _places· the shale is 

Sandstone ~nd shale, soft "ear,thy" diatom~ceous Page. stained . purplish, probably by. the oxidized 

shale interbedded with rather poorly consolidated prQduct of ·some hydrocarbo:J?., either oil or gas. 

white sandstone, usually· of medium grain but in Such coloring. is most pronounced where the 

places finely conglomeratic. Locally indurated shale· is overlain, unconformably by the late 

and containing a few fossils, mainly large oysters Tertiary or younger b~ds, as in the E. ! sec. ~2, 

and pectens. Calcareous lenses are rare ...... ·.. 500 T. 12 N., R. 24 W., but it is noticeable also in 

Shale, diatomaceous; weathers to pinkish outcrops. . 

Contains relatively few calcareous layers like those the steeply tilted shale at various honzons 

common · 1n · un d. . er 1 Ying · d 1 .. VIsion · · ................ . 600 within the formation. 

Shale diatomaceous, like that in overlying division Toward the top of the lower division many 

but containing numerous lenses 'of impure lime- beds of·. arkosic sandstone are interstrati:fied 

stone or fine sandy calcareous clay that weathers with the thin-bedded diatomaceous shale. 

to yellowish outcrops. This zone weathers less 1 ul 

easily than: the overlying and underlying divisions These beds range from fine pu ver ent gray 

and determines a prominent line-of h.jlls ......... · 800 sand that forms inconspicuous outcrops to 

Shale, siliceous; thin bedded, ·brittle, diatomaceous, pebbly sandstone that is indurated by the 

dark when fresh but weathers to light chocolate- addition of .a caJcareous cement .and weathers 

colored· or almost white outcrops. Calcareous out prominently. The soft pulverulent sands 

beds or lenses like those in the overlying beds are 

scattered throughout. Shale somewhat clayey are fairly well exposed north of the 1, 773-foot,_, 

and sandy near the base. 7 ••••••••••••••••• :. • • 2,. 750 hill 2 miles west of Maricopa. From this 

Clay shale, somewhat sandy, containing less diatom· locality they may be traced northwestward 

remains than the overlying division and weather- into sees. 34 and 35, where they are induing to· darker outcrops. Grades into sandy shale 

150 

rated and weather to prominent outcrops just 

of underlying Vaqueros formation ......... ' .... : south of the old Californian _Amalgamated 

4, 800 water wells. Farther northwest, in the north-
TERTIARY SYSTEM. 39 

eastern part ·of T. 32 S., R. 23 E., sandy beds 

occur at several horizons in the upper half of 

tlus lower division of the Maricopa shale. 

. These arkosic sandstones · are identical in 

lithologic character with the finer-grained 

sandstones that are interstratified with soft 

diatomaceous shale and coarse boulder beds 

in the overlying upper division of the formation, and in places, notably in the center of 

sec. 13, T. 32 S., R. 22 E., they resemble the 

beds in the upper division in containing fragments of large oysters and pectens. Thus, it 

is apparent that no sharp line can be drawn 

here between the two divisions, and i~ seems 

more reasonable to believe that the whole 

succession of diatomaceous shales mapped as 

the ~1aricopa shale were deposited in the Temblor Range during one general. period of sedimentation. Yet even though no sharp line of 

separation can be drawn between the two 

divisions, when viewed broadly they are lithologically somewhat different, the diatomaceous 

shale of the upper diVision being much more 

earthy and far less ·silicified th~n that of the 

lower, and the coarse boulder beds far more 

abundant. 

AREA EAST OF SAN EMIGDIO CREEK. 

Diatomaceous shale crops out in· an area 

several square miles in extent between San 

E1nigdio and· Tacuyfll creeks. This shale 

ranges in character· from the hard flinty type, 

containing many calcareous beds that weather 

out to prominent yellowish outcrops, characteristic of the lower division of the Maricopa shale 

in the Temblor Range, to the soft, punky 

white Tariety, containing numerous lenses of 

granitic sand and conglomerate which in places 

carry fossils, ·chiefly large oysters, like the 

coarse lenses in the upper di~sion of the 

Maricopa shale. Characteristic outcro.ps of 

the platy and fairly pure diatomaceous shale 

in the Pleito I-Iills are shown in Plate X, A. 

more than the writer had at his disposal. On 

the map, therefore, the separation of the· 

Maricopa shale into the upper and lower ·divisions is indicated in only a small area along 'the 

axis of the Pleito syncline. 

The shale ·mapped as Mariqopa in the hills 

due west of El Rincon is less indurated than 

the Maricopa shale in which the upper slopes 

of the Temblor Range are cut, is ~ a rule 

somewhat more sandy, and weathers to a 

light chocolate-brown rather than white. Carbonaceous matter is fairly abundant in it, and 

in a few places silicified wood and leaf impres·-

sions were found. The character of the exposures make an estimate of the thickness of 

the shale here impossible. 

Near Muddy Creek is a narrow belt of out-· 

crop of white ~iatomaceous shale which dips 

steeply northward, being almost vertical' in 

places, and is overlain with marked unconformity by dark ~~ay shale of the Etchegoin. 

-N.75"w. 

r.OOOFEET ---J 

S.75"E~ 

FIGURE 4.-Section or rocks exposed on Muddy Creek. a, Alluvium; 

b, Paso Robles formation; c, Etchegoin formation; d, Maricopa shale 

(lower two-thirds). 

The shale itself is precisely like the typical 

Maricopa shale exposed near Pioneer, is highly 

siliceous, weathers almost pure white,. and . 

contains nunl.erous yellowish-weathering cal- 0 

careous beds. Its general character and the 

unconformable relation it bears to the ·overlying 

Etchegoin are well shown in the diagrammatic 

section given in figur~ 4. 

UPPER DIVISION. 

AREA NORTH OF CROCKER SPRINGS. 

It is probable, indeed·_almost certain, that North of Crocker Sp;rings the upper part of· 

the shale between San Emigdio and Tacuya the Maricopa shale is exposed in several areas 

·creeks is the equivalent to both the upper and· where erosion has removed the cover of gravelly 

lower divisions of the shale in the Temblor beds of the McKittrick group. ·Although the 

Rang~. The a~·ea'in which the shale is· exposed· beds included in the Maricopa shale. in the 

east of .San Emigdio Creek is, however, so shat- different areas are sufficiently alike to make 

tered by faults and contains so many huge their correlation certain, yet they are by no; 

landslides that it is quite impossible to interpret means of constant type, and there is a gradual 

the structure and relations of the shales with- increase westward in the amount of coarse 

out spending a great amount of · time-far material. 
40 ·THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

Along the Shamrock anticline in sees. 27,-28, diatomaceous shale which has a pinkish-bro·wn 

29, and 34; T. 30 S., R. 22 E., the Maricopa color when fresh ·but weathers pure white. 

shale is composed of soft, punky diatomaceous The thickness of the upper division of the 

shale with very little interstrati:fied sandstone Maricopa shale exposed varies greatly owing 

and none of the lenses of coarse boulders so to the unconformable relation of the overlying 

common farther·west. It weathers easily to a Paso Robles. 'The thickest section observed 

very loose, fluffy soil, and its outcrops usu~lly is that _west of Fellows, where between the 

occupy an area of low relief, for the shale is siliceous lower division of the Maricopa shale 

much less resistant than the overlying sandy and the. shale-pebble beds of the Paso Robles 

and gravelly beds of the McKittrick. about 3,000 feet of di.atomaceous shale, inIn the eastern part of the Telephone Hills the dura ted sandstone, and coarse gravel is exposed. 

Maricopa shale is composed of clayey diatoma- The upper division of the Maricopa shale 

ceous shale which is much more resistant to here may be divided into two main parts, the 

erosion than that in the Shamrock anticline lower of which is composed predominantly of 

and which, although stained pinkish, does not diatomaceous shale and the upper of. inter-

.show so great impregnation by oil as the shale· stratified diatomaceous shale, arkosic sandsouth of McKittrick. The Maricopa shale is stone, and coarse boulder beds. The lower of 

here faulted up on the east against the coarse these two parts corresponds to the Santa 

detrital beds of the Paso Robles and is over- Margarita ( n formation as mapped in the prelapped on the west by beds of that formation liminary report on the McKittrick-Sunset rein the syncline. that trends northwestward gion, but the upper part was included in that 

through the center ·of the Telephone Hills. report with the overlying McKittrick. 

Along the anticline trending parallel to the The lower part of the upper division has a 

·road south of the Santa Fe tank house in maximum thickness of about 1,500 feet, but 

sec. 18, T. 31 S., R. 22 E., the Maricopa is along most of the foothill belt it averages about 

chiefly very soft white diatomaceous shale .. In 1,000 feet. The variation in thickness is due 

the area exposed north of the tank. house dia- to the lenticular character of the beds, for the 

tomaceous shale of this type is· interstratified separation of the two parts is based upon _ 

with coarse gravelly beds, composed largely of lithologic differences and does not follow a 

fragments of granitic rock and resembling stratigraphic line. The shale toward the base 

closely the beds that form so prominent a part of the lower part of thj.s upper division of the 

of the upper division' of the Maricopa shale Maricopa shale closely res~mbles that in the 

west ·of Midway. The coarse beds are in a underlying lower division, being well lithified, 

general way so like thos·e in the overlying.Paso thin bedded, and b1ittle and in places highly 

Robles that the separation of the two forma- silicified, porcelaneous, or even flinty in aptions is very difficult, and much of the section pearance. Like the underlying division it con0 here included in the Maricopa shale was mapped tains yellowish-weathering calcareous layers, 

as McKittrick in the. preliminary report. 1 but such layers are far less plentiful than in the 

Moreover, the rocks are broken by· a great lower division. Moreover, this lower part of 

. numb~r of faults, making it difficult, indeed, in the upper division of the Maricopa shale is 

·this area where the exposures are· uniformly much less indurated than the shale in the lower 

._ poor, to follow any bed for a considerable dis- division, and the separation between the two 

tance or to correlate the beds exposed in one is recognizable in the topography by a distinct 

. gulch with those shown in another that lies· flattening in the crest lines of the spur ridges 

but a few hundred feet distant. . that trend eastward from the higher part of the' 

AREA IN THE MIDWAY DISTRICT. 

The upper division of the Maricopa shale that 

is exposed along the foothills between Crocker 

Springs and Spellacy Hill (TWenty-five Hill) 

is really the southward continuation ,of the belt 

exposed in the Telephone Hills, and as in that 

area it is composed largely of soft, punky 

1 U. S. Gcol. Survey Bull. 406, 1910. 

Temblor range and cut across the strike of the 

b_eds. 'rhe yellow-weathering calcareous 

beds which are so pro~:rient in the lower 

division of the Maricopa shale and which' occur 

sparingly in the basal beds of the upper division 

aTe lacking in the softer shale. Arkosic sandstones ·and pebbly beds like those that compose 

so much of the upper part of the upper division 

occur sparingly. They are best developed 
TERTIARY SYSTEM. 41 

about 2 miles west of Midoil, where, in the 

NW. l sec. 18, T. 32 S., R. 23 .E., a pebbly zone 

may be traced for a distance of about half a 

mile. • . 

The upper part of the upper division of the 

Maricopa shale is compof:led' of in terstra ti:fi.ed 

diatomaceous shale, arkosic sandstone, and 

ill-sorted conglomerate. .These beds are best 

developed west of Fellows, where ~heir exposed 

thickness is about 1,500 feet. In sees. 1 and 2, 

T. 32 S., R. 22 E., where they are best exposed, 

the lower 100 to 200 feet is massive sandstones 

and gravel. These beds crop out just southwest of the summit of the 2,100-foot hill near 

the center of the NW. i sec. ~· ·Immediately 

above them is a bed of soft white diatomaceous 

shale not over 100 feet thick that crops out in a 

narrow belt which may be traced from the 

2,100-foot hill southeastward· into the SW. 1 

seo. 1. Above this diatomaceous shale is about 

500 feet of coarse granitic gravel and indurated 

arkosic sandstone, with a few thin beds of 

diatomaceous shale, most of them· less than 20 

feet thick. Above these predominantly coarsegrained beds is another zone of diatomaceous. 

shale about 200 feet thick. This shale is made 

up very largely of the remains of diatoms that 

have been altered so little by crushing or by the 

addition of siliceous rna terial .that they are 

readily visible to the eye without the aid of a 

magnifying glass. This shale may be traced, 

on ·the south flank of the syncline that trends 

northwestward through sees. 1 and 2, from the 

SW. i sec. 27, T. 31 S., R·. 22 E., to the vicinity 

of the southeast corner of sec. 1, T. 32 S., R. 

32 ·E.; and along the anticline that lies east of 

the syncline mentioned, from the northern part 

of sec. 35, T. 31 S., R. 22 E., to the west line of 

sec. 6, T. 32 S., R. 23 E. It is the uppermost 

shale formed largely of diatomaceous material 

that ·is exposed in the Midway re.gion. The 

beds above it that are here included in the 

Maricopa shale consist of coarse granitic conglomerate and arkosic sand, some of which is 

well indurated and weathers to prominent 

outcrops. These beds are in lithologic appearance the exact equivalent of the sand and gravel 

bedded with the underlying diatomaceous 

shale. On this account, and also because some 

of the indurated sandstone contains pectens 

and oysters .similar to those that were found in 

the upper division of the Maricopa shale farther 

south and in the lower division in the E. ! sec. 

13, T. 32 S.,·R. 22 E., the gravel and sand above 

the uppermost diatomaceous shale. just described are included in the Maricopa shale. 

The sandstones in which the best fossils were 

found lie in the NE. 1 NW. i seo. 2, T. 32 S., 

.R. 22 E. The only forms found here were 

Pecten estrellanus and a large oyster, probably 

Ostrea titan. Either of these fossils might occur 

in the lower part of the :McKittrick group, but 

it is thQught that the beds are more properly· 

to· be. considered as part of the Maricopa shale, 

because the same species are found in rock of 

the same type at several horizons in the Maricopa shale in other parts of the area shown on 

the geologic map. 

The sanely beds in the upper division of the 

Maricopa shale along the foothills west of Midway are impregnated with oil at .many places, 

especially where they are in contact with the 

diatomaceous shales, and it is from these sands 

that some of the wells in the region about 

Fellows derive their oil. 

AREA IN THE PLEITO HILLS. 

In the east end of the Plei to Hills near Salt 

Creek diatomaceous shale, granitic sand, and 

boulder beds occupy the trough of the Pleito 

syncline. The beds are believed to be the 

equivalent of .those forming the upper part of 

the Maricopa shale in the Temblor Range, and 

the .separation of the Maricopa into upper and 

lower parts is shown equally well in both 

places although it is made entirely on lithologic 

grounds. The presonce of these beds occupying the trough of the Pleito syncline in contact 

with the underlying Vaqueros formation must 

mean that in this pa~t of the region the Maricopa shale is separated by an unconformity 

from the Vaqueros. 'Yet in spite of this evidence the fact still remains that in most of the 

region, particularly in the west end of the San . 

Emigdio Mountains, the Maricopa shale and 

the Vaqueros formatiol). appear to be perfectly 

conformable, and, as ~xplained on page 41, the 

writer believes that the unconformity is local 

and that sedimentation continued uninterruptedly in most of the region during the time 

in which the Vaqueros and Maricopa were 

deposited. 

• IMPORTANCE WITH RELATION TO PETROLEUM. 

The fine-grained diatomaceous shales in the 

Maricopa shale are considered the ultimate 

source of oil in the south end of San Joaquin 

Valley. These shales are formed largely of the 

remains of diatoms and foraminifers, but they 
42 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

contain. also in places a considerable a!fiOUnt only a little more than a mile south of this 

of carbonaceous material, · probably derived. seep they rest upon the fossiliferous Santa 

from terrestrial vegetation. The oil is believed Margarita Jn the north flank. of a small antito have been formed mainly by the decompo- cline .. The overlapping of the Santa Margasition of the minute marine organisms, but rita in this vicinity is shown in the geologic 

very probably the decomposition of the ter- cross section E-E' (Pl. II). 

restrial matter also furnished some oil. The 

oil has collected in part in sandy beds that 

are intercalated with the shale but chiefly in 

the porous beds of younger formations that 

rest unconformably upon the shale. 

The Maricopa shale· is therefore both the 

ultimate source· and a present reservoir of oil, 

and in attempting to estimate the potential 

oil value of a certain region it is important to 

know the character and attitude of the beds 

composing this formation, and also the relation· this formation holds to the younger 

formations that rest upon it, for it is in the 

younger formation that· rests unconf~rmably 

upon the diatomaceous shale that the petroleum is now chiefly contained. 

SANTA MARGARITA .FORl\fA~ION (MIDDLE MIOCENE)." 

GENERAL CHARACTER AND STRATIGRAPHIC 

RELATIONS. 

In the western . part of the San Emigdio 

Mountains are beds of coarse or even pebbly 

sandstone which are clearly littoral deposits 

and contain abundant invertebrate fossils. 

These beds are the near-shore equivalent of 

the diatomaceous shales that constitute the 

unper part of the Maricopa shale in the Temblor Range. They are shown separately on 

the geologic map (PL II), because they. are of 

distinct lithologic type and because the fauna 

they contain permits a definite. correlation with 

the typical Santa Margarita. 

These sandy beds composing the Santa 

Margarita are nowhere exposed resting upon 

the diatomaceous shale that forms the lower 

part of the Maricopa sliale but overlap that 

part of the section and rest unconformably 

upon ·the older Tertiary formations-.the 

Vaqueros and Tejon. · 

The Etchegoin formation (upper Miocene 

and Pliocene) evidently rests unconformably 

upon the Santa Margarita in the San Emigili,o 

Mountains, and the relations are best shown 

in the foothills between Santiago and San 

Emigdio creeks. At the seep on :Muddy 

Creek the Pseudocardium gabbi beds. of the 

Etchegoin rest upon the Maricopa shale) but 

LITHOLOGY. 

In· the foothills of the San Em.igdio Mountains between Bitter and San· Emigdio· creeks 

the Santa Margarita is composed of very 

friable conglomeratic sandstone, usually white 

when fresh but weathering yellowish. The 

color of the weathered surface is not uniform,. 

for the rock is stained deep yellow in small 

irregular areas or along irregular lines, and 

between these stains it is almost as light 

colored as it is in an unweathered outcrop. 

The weathered outcrops have therefore a 

mottled appear~nce when viewed closely, or 

a light-yellowish tone when viewed at a short 

distance. These beds form a rather sharp 

contrast to the prevailingly somber-colored 

beds of the upper part of the Vaqueros formation,· upon which they rest. The sandstone is 

commonly formed of angular fragments whose 

average diameter is between one-sixteenth and 

one-eighth inch, but scattered through the · 

sand are many well-rounded pebbles 2 or 3 

inches in diameter ·of acidic granitic or porphyritic rock and of quartzite. Unlike· the 

overlying . upper Miocene beds the Santa 

Margarita contains J?.O fragments of the fossiliferous sandstone of the Vaqueros formation 

or of the basaltic and andesitic rocks that 

occur ·in the Vaqueros in the San Emigdio 

Mountai.ns. The fact that fragments .derived 

from the Vaqueros formation and the lower 

part of the Maricopa shale are abundant in 

the McKittrick group and yet are absent in 

the Santa Margarita is another indication of 

the existence of an unconformity at the top of 

the Santa Margarita~ 

In this western part of the San Emigdio 

Mountains the Santa Margarita is exposed in a 

narrow belt, in the main not more than 1,000 

feet across, that extends from the east bank of 

San Emigdio Creek nearly to Bitter Creek. 

The maximum exposed thickness is about 900 

feet, but usually the formation as exposed is 

much thinner. West of Los Lobos Creek, 

where the Santa Margarita is folded into a 

dosely compressed SJ11cline, it is only about 

soo feet thick. 
TERTIARY SYSTEM. 43 

Fossils. are fakly . abundant in the Santa 

Margarita between Santiago and San Emigdio 

creeks, and such characteristic forms as Pecten 

estrellanus, A.strodapsis whitneyi (?), Tamiosoma 

gregaria, and a large oyster, probably Ostrea 

titan, were collected at many places. The 

shells are particularly abundant near Los Lobos 

Creek. 

IMPORTANCE WITH RELATION TO PETROLEUM. 

The sandy beds composing th~ Santa Margarita formation in the hills between San 

En1igdio and Santiago cree~ are of relatively 

little commercial importance so far as petroleum is concerned, for the region in wh~ch they 

occur is so broken that the beds can not form 

good reservoirs for retaining oil. 

The Santa :Margarita bec~mes finer grained 

westward toward the Temblor Range, and beneath the valley filling· only a short distance 

north of the foothills of the San Emigdio 

Mountains· it is ·evidently composed in part of 

diatomaceous shale. Where the formation assumes this shaly character it is really to be 

considered a part of the Maricopa shale, and 

the remarks on page 41 regarding the economic 

importance of the shale apply to it; 

MCKITTRICK GROUP (UPPER MIOCENE, PLIOCENE, 

AND PLEISTOCENE~). 

DEFINITION AND GENERAL FEATURES. 

Resting upon the :Maricopa shale in the 

Temblor Range and the Santa .Margarita formation in the San Emigdio Mountains are the 

beds of gravel, sand, and clay that have been 

described collectively as the McKittrick formation.1 These beds were laid down in part in 

marine or estuarine waters, but also in part in 

fresh-water lakes or even subaerially, in .a 

manner similar to that in· which· the alluvial 

filling of the present San Joaquin Valley was 

deposited~ Their unconformable relation to 

the underlying Santa Margarita formation and 

M:aricopa shale is discussed in the descriptions 

of those formations (pp~ 35, 42). With the 

overlying terrace deposits and alluvium the 

McKittrick group is perfectly conformable, and 

a separation of it from these deposits is not 

exact. With a single exception all the beds 

that have been folded or noticeably tilted are 

here included in the McKittrick group, and only 

those beds that now lie in practically the same 

attitude that they had when originally. de1 U. S. Goo!. Survey Bull. 40G, pp. 74-90, 1910. 

posited are mapped as alluvium and terrace 

deposits. The only beds .that are tilted t~ a 

considerable angle which are included with the 

Recent deposits are those about the mouth of 

San Emigdio Creek. The evidence showing 

that these tilted beds are Recent is discussed 

on page 52. 

During the early part of .the period in which. 

the McKittrick was deposited the SunsetMidway region was submerged beneath marine 

waters, but later it was gradually raised and 

during most of -the last h~lf of the period 

practically all of it was either dry land or was 

covered by fresh-water lakes, the condition 

approaching that which now exists in San 

Joaquin Valley. In consequence the beds in 

the lower part of the~ McKittrick group are in 

general finer and much more uniform iri character than those in· the upper half. The change 

in the conditions governing sedimentation did 

not take place suddenly, however, nor was it 

uniform throughout the region, for Jl.t one and 

the same time part of the region may have 

been submerged by marine waters and part by 

brackish or fresh waters, while other parts may 

have been raised above the ·surface of these 

bodies of water to form land. Moreover, tl~e · 

movements .that affected the region seem to 

have been oscillatory, permitting the alternate 

advance and retreat of the sea,. so that parts of 

the region were at one time covered by marine 

waters, at another raised. above sea level and 

undergoing erosion, then occupied by bodies of 

fresh water, at still arwther time once more 

submerged beneath . the ocean. In consequence the sedimentary beds that were deposited during this period show an exceedingly 

·wide range in lithology. 

But despite these local variations, which 

make it difficult to separate the McKittrick 

into definite formations that may be followed 

with precision throughout· the field, it is possible in places to divide the group into two 

main parts. The lower part, comprising those 

beds that were deposited chiefly in marine 

waters, is correlated with the Etchegoin formation of the Coalinga region; the upper part, · 

comprising those beds that were deposited 

chiefly under· conditions much like those now 

existing in San Joaquin V a]J.ey, is correlated 

With the Paso Robles. ("Tulare") formation. 

The J acalitos formation, which in the Coalinga 

region was separated from the Etchegoin formation mainly upon paleontologic evidence, is . . 

I 
44 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

not recognizable in the Sunset-Midway region, than petroleum, has migrated farther and, even 

although it :p1ay be and probably is represented where the Etchegoin is thick, has ~oncentrated 

by .the lower part of the beds here described as very largely in the porous beds of the Paso 

Etchegoin. Robles. 

The total thickness of the McKittrick group Finally, as the barren beds in the upper part 

can not be estimated from the exposed beds, of the McKittrickin any part of this field form 

but from the records of the deep 'wells together a more or less thick blanket over the oil and 

with the data afforded by the outcrops it ap- · gas bearing ·beds, it is important that the thickpears that the group is at least 5,400 feet and ness of ·the group be known in a part of the 

probably more than 6,000 feet thick. Of this region in which drilling is contemplated, in 

the uppermost 2,300 feet of beds are certainly order that the accessibility of ·the productive 

to be correlated with the Paso Robles. ("Tu- sands can be estimated. 

lare"), and the lower 2,100 feet with the Etchegoin. Nonfossiliferous beds that aggregate 

about 1,000 feet may be either part of the Paso 

Robles or part of the Etchegoin. . 

IMPORTANCE WITH RELATION TO PETROLEUM. 

T:lle McKittrick group contains the chief reservoirs of petroleum in the Sunset-Midway district. Oil that has originated in the diatomaceous Maricopa shale has moved upward and 

collected i~ the porous beds in the lower part 

of the McKittrick group, where structural features, principally anticlinal folds, have tended 

to make it concentrate. The clayey beds and 

also the coarse-grained beds whose porosity has 

been reduced by induration through the addition of a cement that has filled the pore space 

between the grains evidently act as impervious 

barriers about the oil-saturated sands, retarding or perhaps preventing the further migration of the oil. The lenticular character of the 

formation is therefore of great importance· in· 

considering the distribution of the oil, both 

vertically and areally. 

The stratigraphic position of the oil-bearing 

beds is not constant throughout the fi.eld, for 

the presence or absence of oil .in a certain bed 

is dependent not upon the position that the 

bed holds in the stratigraphic column but upon 

its position in that particular part of the area 

with reference to the diatomaceous shales. In 

most of the fiel9. the Etchegoin formation is 

thick enough to offer sufficient storage space 

for all the oil that has moved up out of the 

·diatomaceous shales, and oil is.found in it but 

not ~ the overlying Paso Robles. In parts of 

the field, however, chiefly along the edge of the 

main Temblor Range, the Etchegoin is either 

absent or so very thin that the oil has collected 

in the Paso Robles. The Etchegoin formation 

is, however,· the chief oil-bearing formation of 

the district. N aturaJ gas, being more mobile 

ETCHEGOIN FORMATION.! 

. STRATIGRAPHIC RELATIONS. 

In the Etchegoin formation are included the 

beds in the lower part of the McKittrick group 

that were deposited chiefly in marine waters. 

These beds rest unconformably upon the Mari- . 

copa shale and also upon the Santa Margarita 

in the San Emigdio Mountains; where that formation is mapped separately. The relation of · 

the Etchegoin to the Santa :Margarita and to 

the Maricopa shale is described in detail on 

.pages 35 and 42·. 

With the overlying Paso Robles .("Tulare") 

the Etchegoin is perfectly conformable, and the 

separation of the McKittrick group into its 

parts is not easy to make. The accuracy cf 

this separation and the reasons for making it 

are discussed in the description of the ~1cKittrick group (p. 43). 

DISTRIBUTION AND LITHOLOGY. 

The Etchegoin formation is exposed at several points along the eastern flank of the Temblor Range south of McKittrick and also in the 

north flank of the San Emigdio Mountains. 

Some of these outcrops are indicated on· the 

niap, but others, because the belt of outcrop is 

extremely narrow or because sufficient time 

was not available to trace out the separation 

between Paso Robles and Etchegoin, are not 

mapped separately, the beds of probable 

Etchegoin age being included with the overlying Paso Robles. 

The Etchegoin, however, und~rlies practically the whole district beneath the cover of 

the Paso Robles and Recent formations, ~ecoming gradually thicker toward the central 

part of. San Joaquin Valley. 

The 'beds comprised in the Etchegoin are 

·almost wholly near-shore marine deposits,· 

t As hero described this formation probably includes a representative 

of tho Jaealitos formation. 
TERTIARY SYSTEM. 45 

mainly sand, gravel, and clay, which are usually 

·only slightly consolidated but which in places 

are indurated by the addition of a calcareous 

cement. On the whole the Etchegoin is much 

finer and more uniform in grain than the Paso 

Robles. Also as a general rule the Etchegoin is 

· finer grained where it lies at some little distance 

from the main Temblor Range than where it is 

exposed along the foothills of that range. 

OUTCROPS IN THE SAN EMIGDIO MOUNTAINS. 

The Etchegoin formation is exposed in the 

foothills of the San Emigdio :Mountains east of 

Santiago Creek. On Plate II it is mapped separately in the area lying between Santiago and 

Pleito creeks. It is· probably exposed in the 

central part of Wheeler Ridge, but it was not 

found possible to segregate the Etchegoin and 

Paso Robles in that part of the district, and on 

the geologic map all the exposures here are 

. shown as l;»aso Robles. Between Santiago and 

Pleito creeks the Etchegoin is composed 

chiefly of greenish-gray fossiliferous clay shale, 

in places somewhat sandy, especially toward 

the bas~. It has a maximum exposed thickness o:f about 800 feet and rests unconformably 

upon the white sands and gravels of the s·anta 

Margarita formation, as is shown by the complete overlapping of that formation near Los 

Lo bos Creek. Near Muddy Creek, where the 

Santa Margarita is. completely overlapped, the 

Etchegoin rests with marked discordance in 

dip upon the diatomaceous shale in the lower 

part of the J\1:aricopa shale.. (See Pl. X, B~) 

The upper limit of the Etchegoin in this part of 

the area has not been determined definitely, 

an.d for the present only the fossiliferous green., 

ish clay shales and intercalated sandy beds are 

mapped with that formation. The overlying 

beds, which are mainly coarse granitic conglomerate and arkosic sands, are mapped as Paso 

Robles. It is possible that, although the 

upper part of the coarse beds is certainly to be 

correlated with the Paso Robles, the lower part· 

may be of Etchegoi.n age, for the gravelly beds 

show every evidence of conformity with the 

underlying fossiliferous clay shales and are 

lithologically similar to the Etchegoin in the 

Temblor Range. I-Iowever, the clay shales 

and the gravel have been mapped separately, 

because in that way the complicated, structure 

of this region is much more readily interpreted. 

The close relation of the clay shale to the overlying gravelly bed.s is well shown east of Pleito 

Creek, where between the two formations is 

about 250 feet of brownish sand and fine gravel 

intermediate in character between the shale 

below and the coarse sand and gravel above. 

The clay shale that makes up the major part of 

the Etchegoin in the foothills of the San Emigdio Mountains is almost black when fresh but 

weathers greenish gray. It is somewhat sandy 

throughout and, especially near the base, contains beds. of fine-grained arkosic sandstone 

and a few pebbly beds. Semiangular fragments of white diatomaceous shale, eviden~ly derived from the Maricopa shale, are 

scattered through both the clay shale itself 

and the interstratified sandy beds. West of 

Los Lobos Creek the lower 100 feet of the 

Etchegoin is in ph1ces somewhat more sandy 

than the overlying beds and contains a few 

well-rounded cobbles, 2 or .3 inches in diameter, 

of hard rocks evidently derived from the basal 

complex exposed in the central part of the 

range. This part of the formation is filled with 

fossils; the most typical form is Pseudocardium 

gabbi; which occurs in great abundance in a bed 

exposed in J\1uddy Creek near the seep. (See 

Pl. XI.) 

· The Etchegoin between Santiago and San 

Emigdio creeks, to judge from its lithologic 

character and from the fossils it contains, was 

evidently deposited in quiet but relatively shallqw marine waters. East of San Emigdio 

Creek, however, no marine fossils were·discovered in the clay, but a few fragments of bones 

of land animals were found. These were far 

too poorly preserved to be determined generically, but they show that at least a part of the 

Etchegoin here was probably deposited subaerially or in fresh-water lakes. In pl~ces the 

weathered slopes of the Etchegoin bear a striking resemblance to those of the less indurated 

facies of the Maricopa shale, and the soil from 

the·two formations is strikingly similar. This 

fact, together with the presence of pebbles oi 

diatomaceous shale throughout the Etchegoin, 

shows that that formation was derived in large 

part from a land mass composed principally of 

the Maricopa shale.· The coarser, well-rounded 

fragments may have been derived directly from 

a land mass of crystalline rocks, but it seems 

probable· that they were in part· ~econdarily 

derived-that· is, that these granitic fragments 

were plucked from another sedimentary forma-
46 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I • 

. tion, probably the upper part of the Maricopa I . Along the foothills of t~e Temblor Range 

shale,· in which they had been deposited pre:- between Crocker Springs and Spellacy Hill' 

viously. · · · . -(Twenty-five Hill) the Etchegoin has been .recThe predominantly clayey beds in the central 

part of Wheeler Ridge are probably to be correlated with the Etchegoih formation, but the 

lithology of the beds exposed in the ridge is too 

varied to permit a definite separatio.n of them 

into two parts that may be correlated with the 

Etch ego in and Paso Robles· formations.· The 

section exposed in Wheeler Ridge is discussed 

in some . detail in connection . with the Paso 

Robles formation. (Seep. 51.) 

OUTCROPS IN THE TEMBLOR RANGE. 

ognized definitely at only a single point. This 

point lies just west of Fellows, where, near the 

center of the east line of sec. 1, T. 32 S., R. 22 

E., a thin bed of limy arkosic sandstone filled. 

with Etchegoin fossils is exposed ·resting upon 

the interstratifi.ed diatomaceous shale, sand, 

and gravel that are mapped as the upper division of the Maricopa· shale. The fossiliferous 

bed ·is so thin that ·it has been grouped in the 

mapping (Pl. II) with the overlying Paso 

Robles. A fossiliferous bed of this type, probably the sam~ bed that crops out west of FelThe northernmost outcrops of the Etchegoin lows, is encountered in s.everal of the wells, 

formation within the Sunset-Midway district notably in well 9 of the United Oil Co., in sec. 

are those that lie on the flanks of the Shamrock 6, T. 32 S., R. 23 E. 

anticline. about a· mile south of the town of West · of ·Maricopa the beds mapped as 

McKittrick. Here the Etchegoin is exposed on Etchegoin are mainly. fine-grained granitic 

both the north and south flanks of the antiCline sand and compact clay or clay shale. These . 

in a belt that is in few places more than 200 beds are well exposed in the canyon that 

feet across. The formation is here composed drains eastward from the Tannehill ·wells 

chiefly of gray arkosic sandstone, locally indu:~ through sec. 27, T. 12 N., R. 24 W. Some of 

rated but for the most part only poorly consoli- these beds are certainly Etchegoin, as is shown 

dated. In the hill in the NE.! sec. 29, T. 30 S., by the marine fossils that occur in theW. ! sec. · 

R. 22 E., the basal beds are coarse granitic sand .33, T. 12 N., R. 24 w., but the line .of separawith gravelly layers, above which is a pebble bed tion indicated on the map between the Etchecomposed of fragments of granitic, quartzitic, goin and Paso Robles may not be the true one. 

and other hard rocks. These beds are overiain It is, as has already been explained, simply a 

by- clay or clay shale that contains fresh- separation between the fine-grained sands and 

water fossils and is mapped as· the Paso Robles. compact clay shales below and the co~rse 

On the west slOpe of the hill just mentioned' a granitic sands filled with granitic cobbles and 

fine-grained grayish sandstone near the base of diatomaceous-shale pebbles ~hove. Many of 

the· Etchegoin is filled with marine fossils,· the coarser. sandy 'Qeds in the Etchegoin, 

almost wholly Pecten eldridgei. Similar fossils particularly those in the lower part of the 

were found near the east end of the Shamrock .formation, contain oil, and a study of the outanticline in the SW. ! -sec. 27, T. 30 S., R. 22 cr.ops of these beds affords a very fair underE., here also in sands near the base of the·Etche- standing of the way that oil occurs beneath 

goin. No marine fossils were found in the.beds the surface farther east. The most important 

exposed on the ·south flank 'of the Shamrock -characteristics to be noted are. (1) that ·the 

anticline, but the grayish sands 'that crop out oil is found in the coarser-grained beds; (2) that 

on that side· of the fold from the NW. ! sec. 34 it is not 'restricted to the lower part of. the 

northwestward to the vicinity o{ the center of ·formation, as might be inferred from a too 

sec. 29 are evidently the equivalent of the literal interpretation of the statement that the 

fossiliferous beds just described.. · oil sands occur in sandy beds that rest unconFarther west the ;Etchegoin is overlapped by formably upon the diatomaceous-shale formathe Paso Robles formation, and in the Tele- tions, but is found well up in the formation; 

phone Hills the Paso Robles rests· upon the (3) that the sandy beds which contain the 

interstratifi.ed diatomaceous shale and coarse most oil are those that are overlain and underarkosic beds of the upper division of the Mari- lain by beds whose porosity is relatively slight. · 

copa shale. The maximum 'thickness of the In some 'places these less pervi~us beds are 

Etchegoin exposed on the flanks of the Sham- compact clays, but· in other places, notably 

rock anticline is not more than 200 feet. near the Banner well of the Union Oil Co., in 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XI 

NO ........•••.....••...........•• 

A. BREA IN ARROYO NEAR MUDDY CREEK, IN SAN EMIGDIO REGION. 

Note mass of brea occupying center of gulch above figure of man and small patch at right in foreground. The canyon has cut 10 or 12 feet 

below the level marked by this brea. 

B. BED FILLED WITH FOSSILS AT BASE OF ETCHEGOIN FORMATION NEAR MUDDY CREEK. 

The fossiliferous bed is the one on which the man shown in A is standing. 
•. 

TERTIARY SYSTEM. 47 

theN.! sec. 33, T. 12·N., R. 24 W., the impervi- Elk hills report "sea shells" in the productive, 

ous bed overlying the oil sand which crops out . oil sands or in the immediately overlying beds. 

is an arkosic sandstone that is of much coarser The widespread occurrence of these fossiliferous 

grain than the oil sand but is indurated by a beds beneath the cover of the Paso Robles and 

calcareous cement and thus rendered far less their failure to crop out in the foothills of the 

pervious than the. fine sand. Below the oil Temblor Range except in local areas can best 

sand is a conglomerate made up of fragments be interpreted to mean that the Etchegoin and 

of diatomapeous shale embedded in a clayey Paso Robl~s formations were laid down in a 

matri-x that is evidently. composed chiefly of basin that was continuously sinking and that 

comminuted shole like that fonning the larger the Etc~egoin was not deposite~ in regions· 

fragments. It likewise contains much less now occupied by the Temblor Range but only 

pore space than the fine-grained. oil sand and i~ the region of lower relief to the northeast.; 

acts as an impervious barrier. · This interpretation seems much more reasonable than the assumption made in the prelim- AlmA WJ:UmE 'l'RE E'l'CHEGOIN IS NOT EXPOSED BENEATH inary report that the richly fossiliferOUS beds 

THE PRODUC'l'IVE OIL FIELD. that are deeply buried beneath the Paso . 

· The Etchegoin reaches its ma.."{imum devel.op- Robles are the equivalent of the coarse gravels 

ment in the region under discussion in the and diatomaceous shales upon which the Paso 

foothills northeast of the Temblor Range, Robles rests along the foothills of the Temblor 

where it .is .. buried beneath the thick cover of ·Range. As has· already be.en shown, these 

the Paso Robles formation and the alluvium beds are considered in the present report as 

in the topographic basins. Its character and. the upper part of the Maricopa sh~e. 

thickness in this part of the field may be judged 

only approximately from the rather imperfect 

record afforded by the deep wells. The formaPASO ROBLES ("TULARE") FORMATION. • 

GENERAL CHARAC'l'ER AND STRATIGRAPIDC RELATIONS. 

tion is apparently composed largely of clay or . The last formation to be laid down before 

clay shale, sandy clay, and sands, with some the time when the most recent general movehard "shells" which are either indurated sands ments affected the region was a thick terrane 

or moderately coarse boulder beds similar to of gravel, sand, anq cl~y with a very few calthose that crop out in the. area mapped as. careous beds. This formation is much like · 

Etchegoin west of Maricopa. the underlying Etchegoin formation in lithAlong the west side of Midway a few of the ology, differing chiefly in being somewhat 

deeper wells have been drilled through the coarser grained and in having been laid down in 

Etchegoin and have entered the upper part of part in fresh or brackish water and iri part 

the Maricopa shale below. · The thickness of subaerially but not in marine water. It corthe formation here is difficult. to estimate, as responds to the Tulare formation as mapped· 

few of the we~ report ~y P':lSo Robles or and described in the report on the Coalinga 

".Tulare" fossils, and it is only from such re- district.t The older name Paso Robles ·is, 

port.s that the position of the base of the Paso however, used in this report instead of Tulare, 

Robles may be estimate~. · The Etchegoin, which has been abandoned,2 for the reason. 

however, is probably not much over 1,000 feet ·that the two names were applied to essentially 

thick along the western edge of Midway Valley, the same beds. 

but eastward from that locality it thickens The Pas<' Robles formation rests upon the 

greatly, and east of Midway Valley wells have Etchegoill formation witn perfect conformity, 

been drilled in it for a distance of at least 2,000 and in the preliminary report ·the two formafeet and probably for 2,500 feet. tions were mapped and discussed together as 

· The Etchegoin in .this area appears to be the McKittrick formation. Altho~gh, as has 

very largely fine sand or shale, probably of already been shown, it is not possible to 

much the same character as the clay shale separate the two formations in an entirely 

exposed in the foothills of the San Emigdio consistent manner throughout the field, it is 

Mountains, and like that shale it is filled with 

fossils. Almost all the logs of deep wells in 

Midway Valley and m the Buena Vista and 

1 U. S. Geol. Survey Bull. 398, 1910. 

s English, W. A., Geology' and oil prospects of tho Salinas VallcY:-

Parkfl.eld area, Calif.: U.S. Geol. Survey Bull. 691, pp. 219-250, 1918_. 
48 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

thought best to show the separation .in certain 

places, even though it can not be more than 

approximately correct, for the late geologic 

history of the region may thus be understood 

more readily. · 

The separation between the Paso Robles and 

the overlying terrace deposits and alluvium 

is as indefinite as that between the Paso 

Robles and the underlying Etchegoin, for deposition has been practically continuo'll;s in the 

Sunset-Midway region from the end· of the 

. Paso Robles up .to the present time. Except 

near the mouth of San Emigdio Creek,· w;Ilere 

recent stream terrace deposits have been deformed by faulting, all the beds' of this series 

that show ma,rked deformation have been 

grouped with the Paso Robles formatio11-, and 

those that now have practically the same attitude as they had when they were deposited are 

considered Recent terrace deposits or alluvium. 

In parts of the area; notably in the east 

flank of the Temblor Range west of Maricopa, 

in the outer foothills just south of the old refinery at Pioneer, and in the central part of 

Wheeler Ridge, the. Paso Robles as mapped 

includes some beds of Etchegoin age. 

THICKNESS. 

·As nearly as can be· judged from the imperfect records furnished by the deep wells, the 

Paso Robles formation varies in thickness between 2,000 and 4,000 feet in the area northeast of the main Temblor Range. In the east 

end of the Elk Hills wells that start 1,000 feet 

below the uppermost beds of. the Paso Robles 

·exposed in the region penetrate beds containing fresh-water fossils at a depth of 1,SOO 

feet, below which the beds are nonfossiliferous 

to a depth of 2,400 feet, where marine fossils 

taken to be characteristic of the Etchegoin 

occur. The Paso Robles is therefore at·least 

2,300 feet and possibly 3,400 feet thick here. 

At the east end of the Buena Vista" Hills wells 

penetrate more than 3,500 feet of the Paso 

Robles, and on the west side of Midway Valley, 

northwest of Taft, fresh-water. fossils are reported in wells at a depth of 2, 700 feet. In the 

foothills near San Emigdio Creek the gra,vels 

and sands mapped as Paso Robles are not over 

1,200 feet thick, but even in the outermost foothills of the San Emigdio Mountains the beds 

4ip at a fairly high angle northward, and the 

formation evidently thickens greatly in that 

direction beneath the Recent valley filling. 

LITHOLOGIC CHARACTER. 

·The Paso Robles was deposited under conditions that varied greatly from place to place, 

and the variations are reflected in the character of the beds. Likewise the conditions governing deposition did not remain constant in 

any part of the region for any considerable 

length .of time, and the formation shows as 

great a range vertically as it does areally in the 

type of rna terial laid down. 

The general character of the upper part of 

the formation is well shown on the riorth 

slope of the Elk Hills, where it is composed 

of alternating beds of fine granitic sand, clay 

that is in places more or less sandy, and 

coarse gravel. The coarse gravel beds, although 

u8ually exhibiting no sorting of the fragments 

as to size, in many places show' a remarkable 

segregation in the character of the n1aterial. 

For ex·ample, the formation for a stratigraphic 

thickness of 200 or 300 feet may be composed 

wholly of granitic debris-both fine sand and 

coarse gravel-interstratified with beds of 

compact greenish clay. Overlying these beds 

may appear a bed composed almost wholly of 

fragment~ of diatomaceous shale. This bed 

of detrital shale is so free from granitic debris 

and the underlymg coarse beds composed of 

fragments of granitic rocks are ~o free from 

fragments of diatomaceous shale that in many 

places a sharp, almost knife-edge contact may 

be traced· for a distance of several hundred 

feet. One who is attempting for the first time 

to map the areal geology of the region is liable 

to be led astray by the discovery of just such 

sharp contacts and to spend considerable time 

in a fruitless endeavor to divide the beds here 

co'mprised in the Pas<? Robles formation into 

several formations. But sooner or later it 

be·comes· apparent that these various lithologic 

phases do not mark stratigraphic divisions 

but rather only' lenses; some large, some small, 

and that material of a 'given type may occur 

at almost any position in the Paso Robles 

from top to bottom. 

Despite the fact that these variations in. 

lithology can not be shown on the map, they 

must not be lost sight of nor their economic 

importanc·e overlooked, for it. is this very 

lenticularity, this segregation of material and 

the formation of porous and impervious masses, 

that give.s the. formation its power to hold 

the· accumulations pf. fluid, either oil, water, 

or gas. 
I 

TERTIARY SYSTEM. 49 

The fragments of diatomaceous shale in the 

"shale pebble". beds of the Paso Robles are 

almost invariably only slightly rounded and 

vary greatly· in· size, the largest noted being 

about 4 inches in length. They are embedded 

in a clayey matrbc that looks much like that 

con1posing the clayey beds interstrati:fied with 

the underlying beds of coarse granitic debris. 

The land mass that furnished the debris· of 

which the Paso Robles in this part of the area 

is co'n1posed was probably formed of the earlier 

Tertiary Focks like those now exposed in the 

Temblor Range. .Although some of the fragments of granitoid rocks 1nay have come 

directly from the con1plex exposed in the 

mountains at the south end of San Joaquin 

Valley, it is probable that the main source of 

supply lay in the Te1nblor Range, to the west, 

which at that time must have had a considerably greater relief than at present. The 

granitic' debris in the Paso Robles was probably derived fron1 the ·coarse granitic sands 

and conglomerates in the Tertiary. beds there, 

particularly those bedded with the diatomaceous shale in the upper' part of the Maricopa 

shale. The sorting of the material and the 

absence of ·fragments of diatomaceous shale 

in ce;rtain beds are probably n1ore apparent 

than real. It is entirely reasonable to suppose that in the denudation of a land 1nru,:;s 

tnade ·up of interstrati:fied diatomaceous shale 

and coarse granitic debris, such as compose 

the upper part of the Maricopa shale, the soft 

diatomaceous shale would, during transportation, be so :finely pulverized by the grinding 

action of the fragments of hard crystalline 

rocks that it would not be recognizable when 

fmally deposited but would form compact 

clays precisely like those that are bedded 

with the coarse granitic debris in the Paso 

Robles formation. These clays are remarkably compact and fine grained, and even with 

a high-power hand lens it is with difficulty 

that any individual grains may be recognized. 

They must represent deposition in. quiet 

waters, perhaps in large part of wind-blown 

material. Their close· association with coarse 

. gravel, although at first sight somewhat surprising, is really of the same sort as· that 

shown by the material that is accun1ulating 

in the present-day deserts, where the fine 

dust deposited in intermittent lakes is n1ingled 

with the coarse material brought down occasionally by torrential streams. 

109288°-l!)-4 

Near the east end of the Elk Hills various 

clayey beds have been prospected in a more 

or less desultory manner as fuller's earth, and 

it is said that the· clays.• give more or less· 

satisfactory results in clarifying oil. 

On the west slope of the Elk Hills the clayey 

beds are less· conspicuous. The general character of the Paso Robles in the Elk Hills is 

shown in t~e following section, which is taken 

from the preliminary report: 

Section of },fcKittrickforrnation [·upper part, or Paso Robles] 

in the Elk Hills. 1 

Feet. 

Coarse gravel"of considerable variety of rocks; maximum cobbles about 6 inches in diameter ......... 175 

Soft light yellowish-brown sandy clay with white 

efllorescen t alkali. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 

Gravel of equal parts of shale fragments and mixed 

colored pebbles; maximum diameter 3 inches... 50 

-Soft light-yellowish clays like the second bed above. 40 

Gravel of shale fragments and colored pebbles, the 

latter predominating; 4-inch pebbles maximum .. 100+ 

Soft yellowish-brown sand with occasion~! streaks of 

shale and mixed pebbles .... ,................... 75 

Soft yellowish-brown sand with greenish-drab clay 

stratum at base ......... : ..................... ·. 60 

Gravelly sand and clay, upper 15 feet of which is 

stained light purple by alkali; both sand and clay 

are very soft ..... ~. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 100 .... 650 

South of McKittrick the Paso Robles is exposed resting upon the Etchegoin on both 

flanks of the Shamrock anticline. The formation here is on the whole more sandy than it is 

in the east end of the Elk Hills, but the coarse 

beds of graiiitic cobbles are' likewise less 

numerous. The following sectio·n, taken from 

the preliminary report, gives a good idea of the 

character of the formation here: 

Section of },fcKittrick [Paso Robles] forrnation 1 mile southeast of },fcKittrick.2 

Feet. 

Soft sandy or clayey beds and coarse soft ~nd,. 

stones below. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 

Coarse-grained pink granitic sand with numerous 

waterworn shale fragments up to 3 inches long. 55 

Soft sandstone wi,th occasional layers of shale 

fragments, also brown sandstone and firi.e scattered-shale fragments ........ · ........ ; . . . . . . . . . 35 

Hard gray sandstone, some shale pebbles, occasionally brownish and apparently oil stained. . 80 

Greenish and brownish c,lay shale with thin layers of interbedde\1 sandstone. . . . . . . . . . . . . . . . . 64 

Clay shale and sandstone........................ 18 

Brown and pink coarse sandstone with shale 

fragments, also thin partings of shale, at some 

points stained by oil, and clay-filled mud cracks 145 

· 1 U.S. Geol. Survey Bull. 40G, p. 81, .1910. · 2 Idem, p. 80. 
50 THE SUNSET-MIDWAY OIL FIELD, CALIF.-:-PART I. 

Feet. 

Coarse thick-bedded incoherent sandstones with 

. numerous shale fragments.................... 190 

Largely shale and clay, alternate hard and soft · 

· layers; some sandstone and shale fragments; 

chocolate, pink, yellowish, and brown (color due 

to oil iinpregnation)......... . . . . . . . . . . . . . . . . . 290 

Green and brown shale with interbedded yellow 

sands, dark brown and heavily charged With · 

oil ........ ·.· ............................... ~.... 300± 

Waterworn shale fragments forming· a fine conglomerate ............................ ~ . . .. . . . . .. 39.5 

l, 952± 

·In the preliminary report· these beds were· 

described as· the McKittrick formation. Part 

of th~ lowest division recorded may be E~chegoin, for fossiliferous beds of that .formation 

are exposed ·a short distance to the west. 

Most of the section is, however, certainly Paso 

Robles, as fossils characteristic of "the Paso 

Robles (''Tulare") were found a few hundred 

feet south of the .pain~ where the section was 

me·asured in· sandy clays that are either the 

equivalent of the upper part of the lowest 

divisio:p. recorded in the. !3ection or belong in 

the over.lyin.g green and brown shales. 

In the norther~ half of the Buena Vista 

Hills the Paso Robl~s is of much the same 

character as it is on the western slope of the 

Elk Hills and in the hills south of McKittrick. 

The upper part of the formation exposed here 

contains somewhat coarser material than the 

lower part.. Near the middle of the exposed 

section is a zorie about 100 feet thick containing 

several beds of calcareous clay which weathers 

to conspicuous whitish outcrops that may be 

followed on ·the east slope of the-hills from the 

vicinity of theeast line ofT. 31 S., R. 23 E., to 

the northwest quarter of that township and on 

the south slope of the hills in sees. 27, 34, ·and 

35 of the same ~ownship. Most of these 

calcareous beds are not over 20 feet thick, and 

no one bed is traceable separately ·throughout 

the area outlined abov~, but as their outcrops 

aid in understanding. the structure here, the 

approximate position of this zone has been 

indicated on the geologib.map (Pl. II). 

West of. Midway Valley the Paso Robles is 

composed of clay, arkosic sand of variable 

· grain, a11d conglomerate formed largely of 

fragments of diatomaceous shale. Its general 

character is shown by the following section, 

copied with a few alterations from the preliminary report: 

Section of McKittrick [.Paso Robles]jormation in T. 32 S., 

R. 23E. 1 

Feet. 

Superficial gravel dipping gently northeast and 

overlying beds of sand and gravel unconformably. 25 

Gravelly gr~nitic sands_ with thin clayey layers.... 200 

Light-green coarse and fine granitic sandstone with 

tll.in clay layers; also thin hard layers........... 75 

Fine· well-bedded yellow 'granitic sand with thin 

harder seams.'.:................................ 100 

Coarse gray sand with plentiful shale pebbles...... 200 

Coarse and fine gray sand and greenish shales with 

shale pebbles ....... .' ............. ~............ 160 

Gray ·and white sandstone with many shale pebble 

layers ........ .- ................ ~..... . . . . . . . . . . . 100 

Light gypsiferous sandstone with shale fragments; 

contains white porcelain shale layer . . . . . . . . . . . . . 120 

. Oil sands with granitic cobbles at base, sands dark 

brown and coarse; rests on brown diatomaceous 

shale, strongly impregnated with oil (at anticlinal 

axis} ................. ~ . . . . . . . . . . ... . . . . . . . . . . . . 50-80 

--

1,060 

South of Spellacy Hill (Twenty-five Hill), in 

sec. 35, T: 32 S., R. 23 E., the Paso Robles rests 

upon the highly siliceous Maricopa .shale, and 

the basal beds are composed almost wholly of 

fragments of diatomaceous shale. _In places 

these fragments have been cemented together. 

by a siliceous cement, and although the rock is 

as clearly detrita} as the overlying incoherent 

sands and gravels, it appears in hand specimens 

more like a fault breccia. 

In the foothills of the San Emigdio Mount'iiins the Paso Roble!:? is composed mainly of 

coarse gravels and sand, witha relatively small 

amount of clay and fine sand. The conglomerate is for the most part ill sorted; the fragments in any bed show· a ·wide range in size and 

are for· the most part but poorly rounded. 

Besides the cobbles of granitoid rocks which 

compose the bulk of the formation and a relatively small number· of angular fragments of 

diatomaceous shale, the Paso Robles contain~ 

numerous fragments derived from. the Vaqueros 

formation-both of fossiliferous sandstone and 

of the basalt and andesitic agglomerate which 

occur in the upper middle part of the Vaqueros. 

Such fragments are rare, if they·occur at all, in 

the Paso Robles exposed in the slopes of the 

Temblor. Range and in the· outlying foothills. 

The slight areal range of the different types of 

rocks that make up the Paso Robles shows that 

the conditions under which that formation was 

deposited must have ·been very local and tha_t 

the land masses which furnished the detrital 

I U.S. Geol. Survey Bull. 406, p. 83, 1910. 
U . S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XU 

A. TERRACES NEAR MOUTH OF SANTIAGO CREEK. 

B. TERRACES ON LOS LOBOS CREEK. 

Note terraces at several levels. The downward cutting below the lowest terrace shown at the extreme left has been accomplished mainly in 

the last 30 years. 
U . S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE _xm· 

A. OLD JEWETT & BLODGETT ASPHALT REFINERY SOUTH OF PIONEER. 

Looking north from hill above refinery in sec. l3, T. 11 N., R. 24 W. Note wells in Maricopa Flat in distance. 

B. TERRACE GRAVELS ALONG SAN EMIGDIO CREEK ABOUT 2 MILES FROM EDGE OF SAN JOAQUIN VALLEY. 

Looking southwest across the canyon. The gravels here are ahnost 200 feet thick and lie horizontal: San Emigdio Mountain is the !lat-topped mountain at the left of the center. 
0 

QUATERNARY SYSTEM·. 51 

mn.terial were not far distant from the basins of south end of Buena Vista Vrulev. South of. the 

deposition. . . . . Buena .Vist~- I-Iills th~ thickne~~ of the ··valley" 

Wheeler Ridge is fonned. of. coarse conglom- filling almost certainly, i~creases eastward t·o~ 

erato, arkosic sand, and compact reddish and ward thecentralpartof San Joaquin Vrule3r, _and 

greenish-gray-clay which are shown on the map . there the deposits bury so deeply the saP.cls that 

as part of the Paso Robles forn1ation. Most of. are oil bearing in the. productive field that they 

the beds· exposed are probably correctly corre- · can not .be reached _by drilling methods now in 

lated with the Paso Robles .("Tulare"), but vogue. Probably the thickness of the .alluvial 

s01ne of the clays that crop out near the· axis filling in San Joaquin Valley. can never be acof the anticline are probably.il;l the Etchegoin curately estimate9-, as its lithologic character 

for1nation. The time available did not admit is so like that. of-t_he Paso. Robles that well 

of Inapping a dividing line between .the .two records will not give data that are sufficiently 

forn1ations here, and from the character of the accurate to permit a separation of the .two 

outcrops the writer doubts whether a satisfac- formations. . . 

tory separation can be 1'nade. The total thick- In the San Emigdio Mountains remnants of 

ness -of the beds exposed in Wheeler Ridge is stream terraces _may be foup.d up to altitudes 

between 2,5_00 and 3,500 feet. Most of the of at least 2,500 feet abov.e sea level, or i,ooo 

beds in the upper pa:rt 0f the exposed section are feet above the sou_th end of San Joaquiri Valley. 

coarse conglomerate made up of fragments of all Nearly all the larger streams show, especially 

tl1e types of rocks occurring in the central part in their lower courses, a 'succession of terraces, 

of the San En1igdio Mountains. Fragments of the lowest a few feet above the bed <?f the presgranitic rocks . predominate, but boulders of ent stream and .the upp.er well-;marked ones 4;0 

crystalline liinestone, of fossiliferous sandstone, or 50 feet higher. The terraces near the mouth 

of basalt, and of andesitic agglomerate.fr()m the of Santiago· .Creek are -well .shown. in Plate 

Vaqueros forn1ation, and of siliceous diatoma- XII, 4. 

ceou_s shale from the Maricopa shale are very- Besides these terraces in the o~ter foothills 

plentiful. . The clay that is exposed in the cen- there are. Jllany isolated terraces in the upper 

trnl part of Wheeler Ridge, along the anticlinal parts of the canyons which recor.d some local 

11.'\:is, weathers to greenish gray or reddish gray interference with th~ downward erosion of the 

and resembles closely the late Tertiary clays in stream.· A good exa!Jlple of an isolated te:l·race 

the !Cern River field. of this type is Neasons. Flat, in the. canyon of 

QUATERNARY SYSTEM. 

TERRACE DEPOSITS AND ALLUVIlll. 

Pleito Creek, where :a ~mall gently slopipg .area 

:has been formed by a filling of terrae~ gra v.el 

:and sand 20. to'·30 feet. thick. In the upper end 

The conditions that governed -the deposition~ of. the flat fleito Creek has intrenched its.elf j.n 

of the youngest becls.include(l in the Paso Ro- the terrace gravels to a depth of 8 or 10 feet, 

bles formation hav~ continued uninterrupt- but. at the lower end the .creek. has c~t comedly up to the present time, and the sediments plete.ly through the terrace deposit into th~ 

laid. down since the end of Paso Robles time underlying.Tertiary rocks and runs through- a 

include the beds of intermingled sand, gravel, trench 40 to 50 feet deep: 

and clay that fill the larger valleys and cov~r · The deposits .that cover the stream· terraces 

the terraces. range from a veneer of sand.and :fine gravel only a 

In the Temblor Range and in the outlying few inches thick ·to masses of coarse gravel and 

foothills to the northeast only the almost flat- sa.nd 300 to 500 feet thick. The thicke~t .delying. deposits. that fill the structural basins posits in the region are those in the canyon of 

occupied by 1\1idway and Buena Vista valleys S~n Emigdio Creek.. ln the lower 2 miles of 

are mapped as terrace deposits and alluvium. its course this stream traverses a flat-bottomed 

The gently inclined gravels that occur higher· vruley ~bout a quarter of a·mile wide; bounded 

on the range are consi~ered ~part .of the Paso on the south by a precipitous wnll of terrace 

Robles. Despite its broad areal' extent the gravel. In places these gravels lie more than 

thickness of this alluvial filling in 1\fidway Val- 400 feet above the floor of the valley. The 

ley i~ ·relatively small, probably nowhere ex- terraces on .San Einigdio Creek are shown in 

ceeding 300 or perhaps 400 feet, except in the Plate XIII, B. Remnants of a. terrace com-

; 
52 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

parable with the upper part of the terrace on 

San Emigdio Creek are easily recognizable as 

far westward as Santiago Creek and are best 

shown along the old road that leads from San 

Emigdio Creek to Santiago Creek through the 

:southern part of the San Emigdio grant. The 

terrace deposit in the upper part ·of 'the canyon 

-of Los Lobos Creek (Pl. XII, B) records a later 

:period during which the upward mov:ement of 

the region halted for, a while. This terrace 

:may be the equivalent of an extensive terrace 

·west of Santiago Creek, the uppermost one 

:shown in Plate XII, A. 

In places the terrace deposits have been 

·deformed by Recent movements. The best ex-

.ample of such deformation is shown by the 

terrace gravels in San Emigdio Canyon, whicp._ 

.about half a mile from the edge of San Joaquin 

·valley change abruptly from the flat-lying attitude cha1·acteristic of them farther upstream 

.and dip northward beneath San Joaquin Valley 

~t an angle of about 25°. The deformation of 

these gravels apparently has been caused by a 

:fault that lies somewhat north of the· outermost foothills. A curious structure resulting 

from_ this "faulting is shown in ,a small canyon 

:about a mile· west of the mouth of San Emigdio 

Creek. Here the Recent terrace gravels dip 

northward at an angle of 38°, and the whit,e 

grav~ls (mapped as Paso Robles) upon which 

they rest are overturned, dipping southward at 

about 35°. The structure here is shown in the 

sketch in Plate XIV. 

One of the most interesting features of the 

Recent ·terraces in this part of the region is the 

evidence they afford ·that this part of San 

Joaquin Valley is at present rising, apparently 

:at no very slow rate. Most of the stream 

terraces, even those that lie 20 to 30 feet above 

the bed of the present· stream, are bounded by 

dean-cut cliffs whose steep slopes have been 

concealed but little by talus. Moreover, if 

observations made by the· inhabitants of the 

region are to be trusted, much of the downcutting below a terrace level that lies from 

4 to 6 feet above the present stream beds has 

been accomplished within the last 30 or 40 

years. On Tacuya Creek an especially instructive bit of evidence regarding this regional 

movement was obtained. Near the old adobe 

cabins that stand about a mile above the 

mouth ·of the creek water issues from a point 

·in the bankaofoot or two above the stream bed. 

About 8 or 10 feet vertically above this spring 

is an old pipe which, it is said, marks the location t~at the spring occupied some 40 years 

ago, when, as now, the ·spring was about 2 

feet above the bed of the stream. · Near this 

locality, at an altitude comparable with that 

of the old location of the spring, is the top of a 

well-marked terrace deposit through. which 

the stream has cut a trench with almost vertical sides. It seems evident that most of the 

downward cutting represented by the change 

in position of the spring has been caused by a 

very· recent regional uplift: It should be 

noted, however, that ·the ·resistant basaltic 

rock that lies in the upper part of the V_aqueros 

formation cr~sses Tacuya Creek a few hundred 

feet downs~ream fro:m. the spring, and . it is 

probable· that these. rocks have halted the 

downward corrosion of the stream above the 

point where they cross it. The stream level 

between the basalt and the :mouth of the 

creek has probably changed gradually, keeping pace with any regional uplift, but the 

basaltic rocks were probably broken through 

only during periods of excessively high water, 

and it was only _after such. periods that the 

up-per reaches of the stream tended to assume 

what may be· cqnsidered their normal gradient. 

Thus, although the change in the position of 

Tacuya Creek near the spring unquestionably 

records a recent uplift of the region, the rate 

of uplift is not necessarily recorded by the 

rate at which the.stream has intrenched itself 

at this pqint. 

The alluvial filling in San Joaquin Valley is 

composed of coarse gravel and sand brought 

down by the streams, the alluvial fans at the 

mouths of which coalesce to form a gently 

sloping apron along the whole hill front. Many 

of the streams, espeCially those that drain the 

San Emigdio Mountains, are torrential at 

times and carry huge boulders far out. into the 

plains. One of the largest of these_ fragments 

lies more than a mile from the mouth of Tacuya 

Creek and must have traveled that distance 

over a slope of about 200 feet to the mile. The 

boulder is now partly buried in the fine alluvium, but the part visible measures roughly 

20 by 11 by 7 feet. It is shown in Plate VI, A. 

TERTIARY IGNEOUS ROCKS. 

DISTRmUTION. 

In the north flank of the San Emigdio Moun:.. 

tains igneous rocks of two general types occur 

in t}le Tertiary section. The older of these 

0 

0 
-. 

U . S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XIV 

A. 

B. 

UNCONFORMITY BETWEEN LATE TERTIARY GRAVELS AND TILTED PLEISTOCENE OR RECENT GRAVELS IN SAN 

EMIGDIO REGION. 

Looking east across first arroyo west of San Emigdio Creek. 
• 

U. S . GEOTJOGICATJ SURVEY PRO.FESSIONATJ PAPER 116 PLATE XV 

. -~ 

RL:I.IEF \\ ,\P 

C . \ L I F 0 I~ \ I . \ 

lit ot Ill! I\. \I 11.1'\ ~1 \II 'r 

. .:. t ''nn.•o t ,t,·u ..... n) "''''~'~IR"' 

/ 

RELIEF MAP OF CALIFORNIA. 
I ~ i I ._4 ~ j&' 1 l ' ' I 1: 

TERTIARY IGNEOUS ROCKS. 53 

rocks, which lie in the upper part of the 

Vaqueros formation, consist of tuff, andesitic 

agglomerate, and scoriaceous flows ·of basalt; 

the younger 1 which are ill the uppermost part 

of the Vaqueros and in the overlying diatomaceous Maricopa shale,. consist of basalt flows 

and sills. The older rocks are by far the more 

abundant, the youliger occurring only in small 

isolated areas a few hundred feet in extent on 

lower Pleito Creek .. 

The older Tertiary ign~ous rocks . consist 

of flows and agglomerates which do not yield 

readily to erosion, and their outcrops stand 

out in bold relief from those of the Tertiary 

sedin1entary beds. Their weathered surfaces 

are highly and irregularly colored to various 

shades of brown, green, indigo, yellow, and 

black, which are markedly in 'Contrast with 

the somber brown color of the sedimentary 

beds of the Vaqueros formation. These rugged 

and varicolored outcrops of the volcanic rocks 

form a very promin~nt feature of the landscape, 

giving to it in places a distinctly fantastic touch. 

They are exposed in three areas within the 

region shown on the geologic n1ap. The 

largest of these areas extends as a belt ranging 

in width fron1 a few hundred feet to 2 1niles 

between Tacuya and · Pleito creeks; another 

· lies at the·crest of the San Emigqio Mountains, 

near th~ headwaters of Santiago Creek; the 

third area lies near the center· of the W. ! sec. 

11, T. 10 N., R. 23 W., about 2 miles west of 

Santiago Creek. This last-mentioned area is 

so small t}:lat even though its representation on 

the geologic map has been very greatly exaggerated it might easily escape the ~eader's 

notice. 

Flows of basalt, probably the eqmvalent of 

those exposed in the San Emigdio Moun:-

tains, occur in the middle part of the lower 

Miocene section in the canyon of Walker Basin 

Creek, on the ea$t side of San Joaquin Valley. 

Also at the south end of the Carrizo Plain, 

which lies· just west of the Temblor Range, 

basic igneous rocks, described by Fairbanks 1 

as analcite diabase, occur in the Monterey 

group. These rocks crop out near the. northwest corner of T. 10 N., R. 24 W., fr01n which 

they n1ay be traced northwestward for 1nore 

than 25 miles. They are almost certainly the 

equivalent of the older Tertiary igneous rocks 

1 Frurbu.nks, H. W., On rumlclto diabase from San Luis Obispo County, 

·CaUl.: California Univ. Do pt. Geology Bull., vol. 1, pp. 273-300, 1895. 

that are exposed in the San En1igdio :Mountains. 

Tertiary volcanic· rocks occur also on th~ 

south slopes of Molin t Pinos near the . bora~ 

mines in Lockwood Valley interbedded with 

coarse detrital beds. It seen1s probable that 

·these flows are also approXimately the ~quivalen t of, the ·older Tertiary flows exposed on the. 

north slope of the San Emigdio Mountains. 

If they are, their study may afford ·a correlation between San Joaquin Valley and the Great 

Basin province. The Tertiary igneous rocks in'. 

this_ general region will probably be _of greater· 

aiel than any other featm·e in n1aki.ng a gene1~al 

correlation of the va;ried Tertiary sedin1en tary 

formations developed in different parts of the 

region. 

STRATIGRAPHIC RELATIONS. 

The basaltic and andesitic rocks that 1nake. 

up the older Tertiary igneous rocks on the: 

north slope of the San Emigdio Mountains: 

occur chiefly as flows in the upper- part of' the 

Vaqueros formation. Within the area shown 

on the map· no vent was found from which the 

lava was extruded, nor were any dike~ or sill~. 

recognized with certainty. The only point in. 

the foothills along the south end.of San Joaquin. 

Valley at which these rocks are certainly intrusive into the Tertiary lies about 6 1niles due 

east of the mouth of Tejon Pass (Canada de las 

Uvas). Here a dike of basaltic rock, 'evidently 

a part of the main mass of igneous rock, cuts 

the lower part of the Vaqueros formation an4 

the UJ;lderlying Tejon formation (Eocene). 

As has already been explained, the Vaqueros;. 

formation was deposited under varying conditions, part being laid down beneath marin~ 

waters and part subaerially. The igneo~ 

rocks likewise show evidence of having been. 

formed under varying. conditions. Thus the 

pyroclastic beds that form the lower part o~ 

the succession of igneous rocks were evidently 

deposited .in water.. Even some of the coarse 

tuffaceous material. was deposited.~ marine 

water, for in the andesitic tuff west of Santiago 

Creek was found a specimen of Turritella, probably Turritella ocoyana, . a mollusk inhabiting 

marine waters. Much of the n1assive basalt 

and even the scoriaceous lava were probaply 

poured out on the surface of the land. 

East of San Emigdio Creek, especially in. the 

vicinity of Salt Creek and between $alt and 

Tacuya creeks~ there is good evidence of uncon-

.· 
.. 

54 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PA~T I. 

formity- at-the top of the igneolli3 rock. -The 

beds resting upon the basalt in this part of the 

region are almost barren 'of fossils, and there 

might be some question as to the propriety of 

clas'sing them ·with the ·Vaqueros, on acconnt 

of the unconformity that exists between them 

and the underlying bas·alt. The linconformity; 

however, is· believed· to ·be only of local importance ·and 'to occur within the Vaqueros. The 

true position ·of the lavas and tuffs is· shown 

by the outcrops of these· rocks on the headwaters 'of'·Santiago Creek near the southeast 

corner .ofT. 10 N.,: R. 23. W., and ·by the small 

outcrop of andesi tic tuff· in1 sec. 11 of the same 

township. The ·igneous ro~ks appear to· be 

perfectly bedded ·with the overlyirig and underlying beds of the Vaqueros formation and occur 

at the top of what has been described as the 

lower division of that formation. . ' 

... : LIT;HOLO?!C CHARACTER. 

T. 10 N., R. 24 ·W.,· where there is a perfect 

gradation downward from the agglomerate 

into the granitic gravel of the Vaqueros formation through a zone 'about 200 feet thick of 

intermingled ash and detrital material composed of fragments· of granitic rock. The 

character of these transition- beds is shown in 

the tabulated section ·giveri on page 32. The 

andesitic agglomeratic and tuffaceous beds 

vary greatly in thickness, reaching. a maximum· 

between· 500 and 600 feet in the region between 

Pleito and Salt creeks.- The 'agglomeratic arid 

tuffaceous beds were in part deposited in 

marine water, as is shown by ·the 'presence of 

Turritella ocoyana in the agglomerate exposed 

west of lower Santiago Creek.· 

The basalt that overlies the ·andesitic agglomerate 'likewise has its greatest development 

near ·Pleito Creek. It· is probably a little 

thicker than the andesite, although the· fractured nature ·of the rocks prevents· an accurat~ 

-No systematic microscopic study of the estimate·of the thickness. The-texture of the 

Tertiary igneous Tocks from the ·San Emigdio basalt varies· greatly, in· son1e piaces being 

Mountains has' yet been made, and 'the' 'fol- dense~ and· finely granular and· in ot);ler places 

lowing notes are ··based·· almost: -wholly· upon almost glassy.· ·Almost everywhere the rock 

field ·observatioriE! and· examinations of· hand is somewhat scoriaceous, and in place·s it conspecimens.· · · ... · ··;·· · · · !:.; ·: tains amygdules as much as·an-inch in diameter 

·:The ~dlder· Tertiary igneous rocks" are of two filled with natrolite, ·analcite, ·calcite, and less 

main· ·:types~one · a, _light ·"varicolored · rock; commonly -with chalcedony. 

largely 1

·fragrrien:tal and 'probably an' 'acidib 

andesite,· -the··· oth(n•·- ·a:ri· ·a.lffiost bhick basalt ~TRU.~TU:t;tE. 

varying· in texture from a fine-grained compact GEOLOGIC RELATIONS TO NEAR-BY REGIONS. 

rock showing few·tnegascopic crystals to a rock The chief· geologic featur~s of the' Sunsetcontaining· phenocrysts •several millimeters iri Midway district· are on the whole of a type 

length. · Through' most· of-· the region tlie two common to the central part o~ the Coast Ranges 

types:.ate fairly distinct· and' they·liave been of California, but as ·the field is near the 

mapped· separately,~ although at the .western- border of the Coast Range province, many 

most ·poin-t 'where they: are exposed ··along the of these features are in a measure modified, 

&xis of the Devils Kitchen syncline there seems and reflect the complicated· structure of the 

to- be a· gradual change from the andesiticTock mountainous regiQn that lies to the southeast. 

into the overlying basalt, ·and the·separation·is This ·region, em·bracing the San Emigdio and 

only approximate. · · ) : · ~· · Tehachapi mountains, forms both a topoThe andesite is almost wholly fragmental graphic· and. a structural connection between 

and ranges from ·a fine ash to a ·coarse agglomer- the Coast ·Ranges and the Sierra Nevada. 

ate··composed of angular blocks several feet in . Even a 'cursory examination of .the geologic 

diameter.' In ·places· thin flows···are·· bedded· map·(PL II) reveals. a difference in the charwith· the tuff .. '·Th~ ·flows contain· abundant aoter of the geologic structure of the Sunsetglassy' phenocrysts of ·andesine, some· of· them Midway district and the San Emigdio· Mounas much as t·centimeter in length, em·bedded. tains. It is impossible,· however, .from a 

in an aphanitic groundmass; ·The agglowerate study of· so srp.all a region,· to appreciate the 

is light colored, usually being bluisli or· indigo, relations of the geologic features ·of _the one 

though locally dark greerr;· red;· or light buff. area to those of. the other, or to understand. 

The lowest beds· are as a rule composed largely how these features· fit· i~to the structural 

of· ash, especially those exposed in sec. 30, scheme of this part of the State. In order 
STRUCTURE. 55 

that these relations may h~. better understood of this ·point the western ·margin· of San 

a brief outline of the salient 'featilles of the Joaquin Valley is formed ·by the Temblor 

structure of the central part of California will Range, which. heads several miles west of 

be given in the followin5 paragraphs. The the ·point· where the Diablo Range ends and 

accompanying relief map of California (Pl. which on the south joins the San Emigdio 

XV) gives an excellent representation of the Mountains. 

chief geographic features here described. Both the Diablo and· Temblor ranges are 

The central part of California-that is, formed by what may be considered essentially 

th~ region between the latitude of Mount grea·t · anticlip.es somewhat broken by faults 

Sh(l.sta "'and that of Point Conception-em- along the southwestern flanks. They are by 

braces. three major provinces ·that extend as no means simple folds, however, but each is 

elongated belts parallel to the trend of the rather an assemblage of· relatively small 

coast. The eastern province· consists of the anticlines and synclines whose combined, effect 

Sierra Nevada, which is composed predomi~ has. been an· uplifting. or doming of the region. 

nantly of granitic rocks and is essentially a Moreover, just as .the Diablo and Temblor 

block_thathas been faulted up along the eastern ranges have a course somewhat more easterly 

edge and presents a fairly even and gentle than that of the Coast Ranges as a whole 

slope toward the west. The western province. and thus cut obliquely across the mountainous 

embraces the Coast Ranges and may be c<;>n- area, so likewise these miri.or fol~ are not 

sidered as an anticlinorium· "in which the parallel to the course of· the range in w:hich 

rocks, in the main. sedimentary and ranging they lie but in general have a somewhat more 

in age from Jurassic to post-Tertiary, are easterly trend. The. chief obliquely trending 

greatly folded and faulted. Between these anticlines along the western border of San 

two regions of high relief is the tectonic trough Joaquin Valley are shown in figure 5. 

known as the Great Valley ·of California, These· obliquely ~rending folds increase in 

which embraces the Sacramento and San size. and in number so~thward from "the north 

Joaquin valleys. Near its south end ·the end of the Diablo Range. Between Mount 

Sierra Nevada diverges from its prevailing Diablo and Coalinga, a distance of about 150 

southeastward trend and, swinging. to the miles, ·the normal anticlinal structure of. the 

southwest; forms in the Tehachapi .Mo{illtairis Diablo 'Range is broken by only three wella 'Qarrier separating San Joaquin Valley ..from developed. oblique anticlines. South of Coalthe Mohave Desert, a part of the Great Basin. inga, however, the complexity of the folding 

At Tejon .~ass (Cafiada de las Uvas) the· iricrease$ greatly, and at the south end of the 

Tehachapi Mountains abut' against· the San Temblor Range is developed the complicated 

Emigdio Mountains, and this pass is corninonly system of folds that is shown in detail on the 

taken as marldng the junc.tion· of the Sierra geologic.map (Pl. II). 

Nevada and the Coast Ranges. The obliquely tr~nding anticlines appear ~ery 

South of San Francisco the Coast Ranges largely to govern the accumulation of oil on 

are compos.~d of a nti.mber of ranges which, the west side of San Joaquin Valley, for prac- · 

although approximately par8llel to one an- tically all ~he large productiye fields lie either 

other, trend somewhat more easterly than near the axes of such anticlines or in areas in 

the mountainous. belt as a whole ap.d cut which they dominate the structure. A study 

obliquely across it. In this part of 'the State of the position and character of these folds is 

the easternmost of these parallel ranges- therefore of prime importance in estiinatirig 

that is, those which determine the position the values of undrilled areas in this general 

of ·the western boundary. of San Joaquin region. 

Valley-are .the Diablo and Temblor ra:qges. The structure typical of th~ eastern margin of 

.The Diablo Range heads near San Francisco· the Coast Range terminates near Sunset Valley, 

Bay and, holding a course th~t diverges only at the south end of the Temblor Range, where 

very slightly from that of the Coast Ranges the structure lines bend sharply from a southas a whole, . extends southeastward almost eastward to an eastward trend. Beyond this 

. 200 miles to a point some-what south of Tulare locality~ along the·southern margin of the"valley, 

Lake, where it descends through · a narrow the obliquely trending folds so typical of the 

bel~ of·foothills.to.the·vall-ey level. South Coast.·Ranges to the· northwest are not de-
56 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

veloped, but toward the east first the folding 

appears .to become much more complicated and 

then faults come more _and niore to dominate 

the structure. Also rocks much· older than 

those exposed in the Temblor Range reach the 

~ 

<::\ 

3s 

0 

B Cl 

~ Anticl_ine 

I2J ~ Faults 

122° 121° 

GENERAL STRUCTURAL .FEATURES OF THE 

SUNSET-MIDWAY DISTRICT .. 

The region shown on the geologic map may 

be div~ded by a northeastward-trending line· 

drawri through Pioneer into two parts in which, 

Scale 0 ~0 .ItO 60 BO 100 Miles 

FIGURE 5.-Sketch map of part of California showing position of chief anticlines along the west border of San Joaquin Valley. 

surface. All in all, there appears in the San 

Emigdio Mountains a fairly complete gradation 

between the structural features of the Coast 

Ranges and those of the Sierra Nevada. 

although the larger structutal features are 

much alike, the lesser features are very different. Northwest of this line lie the closely 

folded Temblor Range and the .outlying more 
l' I ,1" • 

STRUCTURE. 57 

gently fo~ded foothills, occupying a region in 

which the structural features are typically 

those of the Coast Ranges; southeast of the 

line are the complexly faulted and folded 

San Emigdio Mountains, occupying a region 

in which from west to east there is a fairly 

complete gradation between the · structural 

features of the Coast Ranges . and those of the 

Sierra Nevada. Some details of the structure 

are shown in the geologic cross sections (Pls. 

XVI-L~I, in pocket). 

TEM:DLOR RANGE AND OUTLYING FOOTIDLL 

RANGES. 

GENERAL FEATURES. 

The structure of the east flank of the Temblor Range, including the outlying foothill 

ranges, the Buena Vista and Elk hills, is essentially anticlinal, though it does not consist of 

a single fold, or even a few large folds, but 

rather of a great number of anticlines and synclines whose· combined effect has been an upward folding of the strata along the ·lines now 

occupied by the present Temblor Range and 

the outlying hill groups. .. 

Although the Temblor Range is bordered on 

the southwest by the San Andreas fault, along 

which profound movements have taken place, 

faults are rare in the east flank of the range 

near its south end. In the central part of the 

range the strata are very closely folded or even 

crumpled, but northeastward from. this· central 

area toward San Joaquin Valley the :r;tumber of 

folds within a given: area decreases, the folds· 

themselves are more symmetrical, and the beds 

on their flanks are less sharply flexed. The 

variability in the character of the folding is 

probably due in part to the fact that the rocks 

exposed in the central portion of the Temblor 

Range are older than those exposed in the 

foothills to the northeast and were subjected 

to folding before .the younger formations were 

deposited. IIowever, the forces that have 

been the chief agents iri producmg the structure in this region were active in fairly recent 

geologic time and affected all the rocks in the 

area mapped except those of Recent age. The 

greater complexity o~ the structure in the. 

central part of the rang~ is therefore due mainly 

to the fact that it was here that the forces 

were chiefly active, and it is probable that in 

the outer foothills the older formations are 

but little more deformed than the younger formations which rest upon them and form the 

surface. · 

A ·striking feature of the structure, which 

has been pointed o.ut repeatedly in the preceding pages, is the fact that, although the 

folds are approximately parallel to the course 

of the range, they ~re not exactly so but trend 

somewhat more eastward and as they extend 

into the valley plunge beneath the surface 

some distance from the main range. The 

angular difference in direction between the 

trend of these· folds and the trend of the range 

increases toward the northeast, and the course 

of the outermost folds which forn;1 the Elk 

Hills differs about 35° from that of the Temblor 

Range. Not a single one of the folds in the 

foothills can be .considered as a distinct and 

separate feature-that is, as a dome isolated 

from the structural features of the main range. 

They are all really but spurs that branch out 

from the major fold of the Temblor Range an;d 

overlap one another to a greater or less degree. 

The overlapping of the secondaty anticlinal 

folds is well shown in the foothills of the 

Temblor· Range west of Midway by the Midway, Spellacy, Thirty-five, and California Fortune anticlines; ·in the Buena Vista Hills by 

the Rudisill, Globe, and Sixteen anticlines; 

and to a less marked degree in the Elk Hills by 

the three small anticlines on the south flank of 

those hills. This oblique arrangement is characteristic of all the folds along the west side of 

San Joaquin Valley' (see fig. 5) but is most 

marked toward its south end and is particularly well developed in the area shown on the 

accompanying geologic map (Pl. II).· 

The individual folds are short. Few are 

traceable for more than 15 mil~s, and most of 

them for less than half that distance. In the 

foothills the ·folds are usually grouped and a 

series ·Of small anticlines taken together form· 

a structural ~plift. This grouping or bunching 

of the folds is particularly noticeable in the 

north half of the· Buena Vista Hills. Here the 

strata are folded upward along two major 

zones-one extending from the . southeast 

corner ofT .. 31 S., R; 23 E., northwestward to 

the middle of the west line of that township; 

the second from the middl~ of the east line to 

the northwest corner of the same township.' 

Along each of these zo11es of uplift the strata 

are bent or puckered into several small parallel 

anticlines and synclines, with the main bending 
58 THE SUNSET-MIDWAY OIL FI~LD, CALIF.-:-PART I. 

upward. It is probable that the ·individual them in that the downward folding rather than 

folds are really surficial features and that at ~ the upward folding ·is dominant." From the 

ctepth of not more than a few hundred ·feet at . well records; however, it' appears that these 

most they merge to form two anticlines,· one. downward-arching folds are much more regular 

along each of the zones of ·uplift mentioned. than the upward-arching folds and that most· 

The longer anticlines are un~ulating, -·in of them are simple troughs. 

some places pitching to ·the north or west and· sTRUCTURAL DETAILs IN THE FOOTHILLs. 

in other places to the south or east, thus fash- The details of the st~~cture are in the main 

ioning the anticline into a series of domes. sufli'ciently well shown on the . geologic map 

Most of the folds, however, pitch in but a (Pl. II) and the map showing the strD:cture o( 

single direction-usually south or east toward the oil sands (Pl. III) to make a complete 

San Joaquin Valley. written description of them unnecessary, but 

Many of the small folds in the Buena Vista one or two features, particularly those which 

and Elk hills are sharp puckers, the ·strata that · have some direct bearing on the occurrence of 

crop out only a few hundred feet from the axis. petroleum that might othe~ise es~ape notice, of the· fold being tilted ·very commonly as will be .describ~d here. ' 

much as 30° and in places as much as- 70° or 

· 80°. · As a rule, however~ these sharp· folds are ELK HILLs. 

the shorter ories and; as· nearly as may be The Elk Hills. c"ome as near to being an 

judged· from the ·well records, the shallower isolated dome as any other group within the 

ones. These si:nall sharp folds ·'are therefore area mapped, .for the twe anticlines -that 

isolated and not nearly so favorable ·for the together form their dominant structural feature 

accumulation of oil as the less sharply defined plunge not only southward beneath San Joaquin 

but broader and deeper· folds.· The fact that: Valley ,but also northwestw_ard,, thus forming 

the smaller _anticliil:es are really no ·more· than a structural saddle between the. Elk Hills and 

surface ·wrinkles is well shown by the small the main range about McKittrick. ·These antianticline' that lies:just' west of the main one- clines trend· northwestward through the center. 

the ·Honolulu· antiCline-in· the south ·half of' of the. hills·. They are broad and low~ the beds 

the Buena· Vista Hills: This· small fold-the rarely being tilted more than 5? or:6°~:meither. 

Sixteen ·anticline-affects the surface· beds flank~· Although the anticlines are separated 

along a: line that· ·extends· from 'the ·northern· at the surface· ·by a shallow trough, it is almost 

part of sec. 2, T. 32 S., R.' 23 -E-.; southeastward certain that they Unite at no-great depth and 

to the N. f sec. 8, T. 32 S.,· R. 24 -E.; and· form.asingle anticline.· The trough s-eparating 

probably across· the· topographic depression fu them is so shallow..:_the dips ·on its flanks are 

the central part ·of sec·.": 8 to the northeast in most places not more than 3° or 4o.:_that 

corner of sec.· 16. The position of the -axis· of for all _practical purposes the two anticlines 

this fold is shown <?n the geologic map (Pl. 'II). may be· considered- one, even at the surface. 

·The producing oil sands that unde:rlie the.area In places· one. or. the other of them is interat a depth of about 2,000.feet are; however, ·not rupted--:for example, near the west end of the 

folded into a· single anticline but ·rather into a hills, for a distance of a mile or so, the strata 

series of benches that extend out -.from- the dip northward· from the axis of the more 

main: IIonolulu. anticline.· · The structure of the southerly fold· to .the north edge of the hills,· 

oil sands is shown by the underground contours· thus interrupting the northerly fold. 

on Plate III. . ·Much of the south slope of the ~lk Hills is 

·The chief synclines in the foothills-that is, approximately a dip slope, ·but the regularity 

the synclines separating the zones of upward of the structure is interrupted by three sharp 

folding-are· of' courSe not so susceptible of' puckers along which the strata are· tilted in 

study as the anticlines, for in them the.bedro·ck . places to an angle of 50° or 60°.· These folds 

is de~ply buried beneath·a thick alluvial cover. are clearly only very minor features·, and it is 

Analogy might suggest that these ·troughs ·are: doubtful if they affect -the strata that· lie 

formed by a collection ·of small anticlines and deeper· than a very few ·hundred feet below 

synclines: similar to.those in the zones of·uplift the surface. ·That these .folds are of no -more 

in the··Buena Vista Hills but ·differingtfrom than local importance is· shown by ·the fact 
STRUCTURE. 59 

that the synclinal and. anticlinal axes are very 

close together and' by the narrowness · and 

sharply outlined nature of the belt· in which 

the beds are steeply tilted. 

separately named, being call~d the Globe, 

United, and Honolulu anticlines.. Their position is well shown· by the· underground contours on Plate III.· 

DUENA VISTA HILLS. 

The pass that cuts through the }fills in sec. 

- 36, T. 31 S., R. 23 E., is as truly a reflection 

In. the Buena Vista Hills there are two zones of the structure as the hilis therriselves .. .:All 

of upward folding-one connecting with the the short folds that lie north of the pass plunge· 

Shamrock anticline near the southeast. cornet southward, and the Hon,olulu anticline and 

of T. 30 S., n: 22 E., and extending southeast- the northward extension of the Sixteen antiward to the middle of the east line· ofT. 31 S., cline, on the. south of it, plunge northward .. 

R. 23 E.; the other connecting with the main The northward plunge of the Honolulu antirange at the south end of the Telephone Hills cline is particularly notable and is well shown 

and thence trending first eastward and then by the contours.in the·structure map (Pl. III). 

southeastward to the extreme southeast end of . The north edge of the Buena Vista Hills, 

the ;Buena Vista Hills. .In each of these zones east· of the pass ·through sec.· 36, T. 31 S., 

or b'elts of upward folding there are a number R. 23 .E., is well defined, .the angle betwee~ 

of short parallel folds which overlap 'one the slope of the valley and sl~pe C?f the hills 

another in an irregular way .. Such short folds being more sharply marked than it is, in the 

are most plentiful in the central part of the Elk Hills. This, too, is a. reflection of the 

southerly belt, near the· pass through the structure, for the strata qip at angles of J5° 

Buena Vista Hills at the southeast corner of to 20o in the outer part of the Buena .Vista 

T. 31 S.; R. 23 E: ·.. Hills., whereas at the edge. of the Elk Hills 

The southerly zone is· the larger and the the dip is rarely over· half that much. Along 

more important so far as the occurrence of oil. the .southwest flank of the .. Buena Vista IIillE! 

is cQncerned. Although the strata are steeply east of Taft there ; is a· similar . t);lougP, less 

tilted along the northerly zone of folding, the marked. tend~~cy for the dip to .be ~lJghtly 

folds in that zone in many ways closely resem- gr~ater. near the .edge of .Midway Valley tha.n 

ble the small folds which lie on the· south flank it is .closer to the crest of the J:.ills .. A c~oss 

of the Elk. Hills· and are to be considered as section across .the south end ·of the Buena 

only short surface wri:p.kles. Toward its south V~ta .Hills .therefore· shows the fo.id .as a fhitend---that is, in the eastern part of T. 31 S., topped arch, not ~ regula~ly. shap~d .dome. 

R. 23' E'.-the folds comprised in this northerly . · FOoTHILLs wEsT OF MIDWAY vALLEY. 

zone probably do no.t greatly affect the strata 

that are buried more· than a few hundred feet The chief structural features in the foothills 

beneath the surface. of the .. maio.· Temblor Range west of Midway 

The southerly zone of upward folding,. which. Valley and south of the Globe anticline are 

. extends from the vicinity of sec. 15~' T. 31 S., the Midway, Spellacy, and Thirty-five antiR. 22 E., southeastward to the extreme s'outh- clines. Each of these folds ·heads near the 

east end of the Buena, Vista Hills, is not a central part .of the range but in trending 

simple arch· or even a series .of small parallel ·southeaStward eac~ edges out into the outeranticlines;for the chief fold plunges ·alternately most foothills and finally . plunges beneath 

to the·east and west, fashioning the anti.cline Midway Valley; The three folds have a stepinto a series of short anticlines or. elongated like arrangement, each of the folds on the 

domes that are separated . from one anothe.r south commencing west of the point where its 

by structurally low points or· saddles. The neighbor on the north plunges beneath the 

separate parts of I the uplift are not very dis- valley. 

tinct at the surface, altho.ugh the . topograp4y The beds near the crests of these three antidoes in a measure reveal their presenee, but. clines· are a little less sharply flexed than those 

at the .horizon of the oil sands they .are· very along the folds ip. the north end of the Buena 

rnarked, arid they have a very definite influence Vista :Hills, ·the dip· here rarely being more 

upon the accumulation of the oil. 'The sepa- than 30°. The decrease in dip on the· north- · 

1·ate don~es are therefore, in the present·~epqrt; I east fla'nk is ·regular, but: on· the .southwest 
60 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

flank there appear various irregularities such 

as small faults, or breaks in the synclinal 

troughs that separate these three anticlines 

from the main range. These irregularities in 

structure are most numerous on the southwest 

flank of the Spellacy anticline. 

The. Spellacy anticline is somewhat broken 

near its northwest end, but the short anticline in the Maricopa shale 2 miles south of 

Fello:ws is really -the· northwest end of the 

Spellacy anticline, although not connected 

with it at the · surface. Near the crest o'f 

Spellacy Hill (Twenty-five Hill) the Spellacy 

anticline ochanges its course 'rather abruptly 

from southe'astward to eastward and passes 

through the central part of sec .. 30, T. 32 S., 

R. 24 E. Near the center of the south line 

of sec. 25, T. 32 ·s., R. 23 E., a sharply marked 

anticline is traceable for about half a mile. 

This fold has frequenqy been taken as the 

southeast end of the Spellacy anticline, with 

which it is in a:lmost perfect alinement. It is, 

however, really but a minor surface pucker, 

for the axis of the main fold clearly lies fully 

half a mile farther north. The·relatively slight 

importance of this fold is indicated by the 

close approach of its axis to that of the. syncline on the southwest, which is one of the 

chief secondary folds, and is here equal in 

size and parallel' to the Spellacy anticline. 

The California Fortune anticline may be considered the westward extension of the Thirtyfive anticl~e-offset, it is true, and separated 

from that, fold by the Phoenix syncline, but 

for all that the two are no more to be regarded 

as distinct structural features t~an the. small 

anticline _in the Maricopa shale 2 miles ~outh 

of Fellows is to be regarded as a feature 

distinct from the Spellacy anticline. 

SAN EMIGDIO MOUNTAINS. 

GENERAL FEATURES. 

in folds. The chief reason, however, for the 

dominance of faults over folds is to be foU!ld 

in the fact that in this region the Sierra 

Nevada abuts against the Coast Ranges, and 

the forces causing deformation in both pro-

-Vinces have left their imprint upon the structure in this meeting ground. The action of 

these combined forces was evidently so intense 

that' probably the sedimentary beds, though 

fairly flexible, could not simply by folding 

have adjusted· themselves to ·the stresses set 

up, ~ven if they had not been li.llderlain at 

fairly shallow depth by a rigid foundation such 

as was afforded by the crystalline rocks. 

In the western end of the mountains, where 

the Tertiary sedimentary rocks are thick, 

those beds are folded ·into an infinite number 

of short irregular folds and broken by a 

multitude of equally j.rregular faults. Many 

of .these fqlds ll.lld faults are shown on the 

geologic map (Pl. II), but a grea·t map.y others 

are of necessity omitted, and the structure 

there is eve~ more complicated than ·the map 

indicates. East of Santiago Creek the folds 

are relatively few, and most of them are shown 

on the map. In contrast to those in the west 

end· of the mountains, the folds here are 

mainly open, few are closely compressed, and 

only one or two small ones are even locally 

overturned. The faults are, however, increasingly abundant toward the east, and many of 

them have almost certainly been overlooked, 

for the outcrops ·do not preserve evidence of 

faulting for any great length of time. 

One feature worthy of note in comparing the 

structure of the north flank of the San Emigdio 

Mountains with that of the Coast ·Ranges, 

to the northwest, is the fact that here in 

many of the -block~ bounded by faults the 

strata are folded into both anticlines and 

synclines. The faults are apparently entirely 

independent of the folds in position, and 

In the San Emigdio Molintains the structure many of them i:q, direction .. In the central 

is dominated by ·faults and not, as in the east part of the Diablo Range the anticlines are 

flank of the Temblor Range, by folds. In this characteristically faulted, and in the fault 

region. the grani~ic and. metamorphic rocks blo.cks the sedimentary rocks are folded into 

under he the Tertiary sedimen.tary rocks at a synclmes only. An excellent . example of 

much shallower dep~h than In the Temblor structure of this type is shown by the region 

Range ~d .crop out~ the central part of the .about Priest Valley, at the heart of the range 

S~~ ~~Igdw Moun tams, ~nd the presen_ce of west ·of Coalinga. The structure in this area 

this ngid mass of crystalline rocks so close to is mapped and described in 'an earlier paper.~ 

the surface may have been a large factor in 

causing the forces that produced the deforma- 1 Pack, R. W., and English, W. A., Geology and oil prospects· of 

Waltham, Priest, Bitterwatcr, and Peachtree valleys, Calif.: U.S. Geol. 

tion to express themselves in faults rather tha:n survey nun. 581, pp. mHoo, 1915. 
STRUCTURE. 61 

east, they are far more plentifui than they are 

anywhere in the San Emigdio Mountains. 

The faults of the easterly system are represented by the fault that crosses Santiago Creek 

near the southwest corner of the San E~igdio 

grant, by the ,one that parallels Williams 

Creek, and by the one that crosses San Emigdio 

Creek at its mouth. . 

DETAILS OF STRUCTURE. 

The largest single structural feature in the 

San Emigdio Mountains is the San Andreas 

fault, or the "earthquake line," as it is commonly known because of the fact that movements along this fault farther p.orth were the 

cause of the San Francisco earthquake of April, 

1906. This fault is traceable from a point north 

of San Francisco southeastward for several 

hundred miles to a point in the desert in the 

southenst corner of the State. ·Movements 

along the fault have bee~ profound and in the AREA WEST OF SANTIAGO CREEK. 

· area shown on the map have resulted· in aver- The strata in the foothills west of Santiago 

tical displacement that aggregates many hun- Creek are so crumpled and broken by irregular 

dred o~· perhaps several thousand feet. Some faults that about the only generalization which 

idea of the magnitude .of the movements along can be made regarding the structure here is 

this line may be obtained hy a view of the that the complexity increases as the San 

.section on the east branch of Santiago Creek Andreas fault is approached. 

near the southern edge of the area shown on I~ the outer foothills are the Cienaga synthe geologic map. I-Iere the Mesozoic granite cline and the Pioneer anticline, which with the 

on the north side of the canyon is in fault con- Wheeler Ridge anticline are the most easterly 

tact with the Miocene sands and gravels on the of .the folds typical of the Temblor Range. 

south. (See'diagrammaticsectionE-E',Pl.II.) The Cienaga syncline is asymmetric, the beds 

Very little evidence was obtained as to the standing almost verti<::,al upon its south limb 

precise nature of the faults, for the rocks they but dipping southward at only 10° or 15° on the 

cut are not well suited to retain such evidence north limb near its eas~ end. 

very long in recognizable form. From the The Pioneer anticline is almost sy~metrical, 

1neager evidence available, however, it seems and east of the fault down Cii:maga Canyon.· 

probable that most of the faults are normal the beds are usually tilted not more than 20° 

and that the dip of the fault planes is usually on either .flank. Both anticline and syncline 

high. Certainly there is no evidence here that plunge· eastward beneath the valley, but it is 

any fault is a thrust with even a moderately -prob_able that both continue to. affect the 

low dip. The faults in the north flank of the Tertiary. strata beneath the alluVIal cover as 

San E~~gdio Mountains ·,appear to belong to far eastward as t?~ east line ?f R. 23 W . 

. two mam systems, those of one trending Th~ exact po~1t10n at whw~ the fault that 

between N. 40° W. and N. 75° W. and those extends down C1enaga Canyon 1s drawn on the 

of the other between N. 45° E. and due east. maps. (Pl. II, III, and XLIV) is determined 

It may be that the San Andreas fault which largely by the . topography. There may be 

would fall into the first-named system,' should and probably are other faults in the Tertiary 

really be considered separately, for it appears rocks. abo~t Old Sunset, but the co;er of 

to have a slightly more westerly trend than alluVIum h1des them completely. The C~enaga 

most of the other large faults of this system. Cany?n fault does not cross the Cienaga 

The faul-ts of the northwesterly system are syncl.Ine, for although that fold makes a very 

represent~d in the area. shown on the map ab.rupt bend, beds may be tra~ed uninter-

(Pl. II) by the fault that. parallels the main ruptedly across the canyon. 

branch of San Emigdio Creek above its connec- AREA EAsT oF sANTIAGo cREEK. 

tion with Williams Creek, by the one that The chief folds in the Sa.n Emigdio Mounterminates on the w~st the granitic outcrop tains east of Santiago Creek are the· Devils 

which lies north of the Devils Kitchen syn- Kitchen syncline, the Pleito syncline, the 

, cline, and by the one that passes through the unnamed anticline which separates these two 

hills just west of El Rincon. The faults of this troughs, and the Wheeler Ridge anticline. 

system increase in size and in abundance ~I these folds are fairly synunetrical and open. 

towa~·d the eastern edge ~f the area mapped, The Devils Kitchen syncline is one of the 

and 111 the Tehachapi l\1ountains, still farther most pic~uresque features. of the whole region, 
62 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

for where San 'Emigdio Creek. has· cut a deep flexed; it .is certain .that the change in the 

. canyon directly across .it the massive rooks in trend of the· fold is C:aused by the fault and not . 

the lower .part .of the. Vaqueros formation are by a simple plunge of the fold. 

clearly exposed,. ·and- one standing on the west The northwestward-trending fault ·that· 

side of the canyon may look across and follow ·passes through othe low hills west of El Rincon 

·with his eye .som~ individual bed from. the and across Wheeler Ridge just west of Coaloil 

point where it dips northward at -Eagle Rest Canyon is one of -the chief structural f~atures 

fully around the trough of the.syncline to the of the region.· It or a parallel fault evidently 

point on the north flank .where it dips south.:. . continues southeastward along the upper part 

ward. An excellent view of the syncline is of .Grapevine Canyon (Canada. de· las Uvas) at 

given in the photograph. f?h~wn in Plate. VIII. least as far as Castac Lake, which lies 4 miles 

East of San · ·Emigdio Creek the· syncline · southeast of the southeast corner of the area 

pitches directly eastward at an angle of about shown on the geologic map (Pl. II). · In spite 

20°, and on the ·opposite side of the hill shown of the evident large size of this fault it is prac.:. 

in Plate VIII,· the massive ·sandstone and tically impossible to get satisfactory ·evidence 

conglomerate crop out in the. c~nter of the iii the field either as t'o. its exact position in 

syncline and, weathering to rock slopes almost the foothills or as to the' attitude of the fault 

barren of vegetatio·n in places, form a great plane. The shale that crops out in the area 

rock trough. · just west of El Rincon is so crumpled, and the 

The axis of the anticline separating the whole area lying between the axis of the 

Pleito and· Devils Kitchen sjrnclines has been Pleito syncline and Wheeler Ridge is so com-

. mapped for a. distance of only 2 or 3 miles plex a mass of landslides .that the attitude of 

between San Emigdio and Pleito creeks. ·The the outcropping· rocks gives ho clue as to the 

fold continues westward beyond San Emigdio true structure. Eve:J;l where the fault is 

Creek, however, for it is along this fold ~hat supposed to cross the line of contact between 

the granite exposed north of the· Devils Kitchen- the granite and the Tejon the surface is so 

syncline crops out. Some importance attaches . covered with the granitic debris of rock slides 

to this fold, for ~ong it,· if anywhere on the from the higher parts of the range that the 

north flank of the San Emigdio Mountains, the ·offset shown on the map is almost wholly hypooil which may possibly have originated in the thetical. 

shales of the Tejon formation ':Vould be· ex- A fault paralleling the fault just described 

pected to collect. The possibility that oil crosses Tejon Pass (Canada de las Uvas) prachas collected here is discussed in another part . tically at its mouth, and other short. parallel 

of the.report (p. 170). , faults cross lower Sa1t Creek. Moreove1•, the 

The Wheeler .Ridge anticline is a slightly steep ·northward· slope .of· the shale hill lying 

asymmetric. fold that heads in an area of north ·of the· axis of the Pleito syncline and 

colll:plic~ted struc~ure j~st west ?f Coaloil just west of the mouth· of Salt Creek suggests 

Canyon and· runs m a shghtly curvmg course that it too. is determined by a break paralleling · 

first eastward ·and then so~theastward for the larger one which lies a mile to the northeast. 

some 6 miles, :finally ·plungmg beneath the . Both the fault alo:riO' the main branch of 

valley. In a reconnaissa:n_ce report on the San. Emigdio Cr~k· a~d -that up Williams 

south end · of San Joaqum Valley · Robert Creek or faults parallel with and close to 

Anderson 1 described the Wheeler Ridge anti- these' faults almost certainly continue southcline as. plunging westward 'West of Coaloil ward to the' San Andreas fault, forming thus a 

Canyon and likened-the structure here to that trianO'uhtr fault block of which San Emigdio 

of a dome. The swing in the co~e of tb:e .anti- Mou;tain is the highest point. The fault up 

cline near the Coaloil Canyon is, however, not the main branch of th.e creek is dist~nctly · 

due to a westwar~ p~unge. A cross. fault younger than the Devils Kitchen syncline and 

passes through the hills JUSt west of El Rincon, offsets the axis of that fold .. This fault does· 

and although the field evidence is not quite not seem to cross the fault that passes down 

clear as to whether the fault has cut the fold· .or Williams Creek and is probably older. 

whether the folding was sv.bsequent to the The eastward-trending fault that passes 

faulting and only the beds. east of the fault were thro·ugh the Tejon rooks about 2 miles above 

1 u.s. Geol. survey Bull. 471, pp. 123, 124,1912. the junction of Williams and ·San Emigdio 
. · PETROLEUM. 63 

creeks is a· relatively small break. -Its Telation to the fault up San Emigdio Creek· is not 

clearly shown. 

PETROLEUM. 

HISTORY OF D~VELOPMENT. 

Meantime Charles :Ba.rnard, .who had. operated in the 

Ventura oil fields, * * * secured a 20-year lease in 

conjunction with Jewett and' Blodgett on the 2,000 acres 

held by the Sunset Oil' Co. * * *· .Barnard brought 

from Ventura a standard rig with which he began operations on sec. 21, 11-23, near the site of DeWitt's second 

attempt .. Before he ha_d gone 300 feet he had l.ost three 

Ti1e pres~nce of brea and seeps of heavy oil strings of tools in the well and decided to move to theSE. t 

in the foothills of the Temblor Range at. the sec. 13, 11-24 * * * · ·Here, at 300 feet, he got suisouth end of San Joaquin Valley has been phur water that flowed' over the ca.sing. He then sold 

out his interest in the lease to Je,wett & Blodgett. * * * 

lmown for at'least '50 years, .but owing in part Mr. Blodgett, who was the active member of the firm 

to a lack of appreciation of the value of the had bought a standard rig from tP.e _Columbian ·oi·l Co.: 

petrqleum resources .-of California as a· whole, which, P.ad abandoned drilling at McKittrick and was 

and especially to the lack . of ·transportation · drilling along the bre~k of the hills at Suns'et, with indiffacilities in this portion of' the State, the Sun- ferent success. He got oil in small quantities, but there was no transportation sa.ve 'by teams. to Bakersfield, and 

set-Mid\vay district received scant attention the cost of hauling Waf! prohibitive. 

until the nineties. Even then the first serious In .1891 Jewett & Blodgett began making asph~lt at 

efforts to develop the resources· of the region Sunset, quarrying the native product .from the beds where 

were concerned with· adphalt rather than with the oil had seeped out and dried and melting it in open . kettles with a small amount' of cmde oil for a flux. The 

petroleum, and the production of oil in the hot asph~It was drawn off. into boxes and the sediment of 

S.un~et-Midway field may be said to date from sand an<;l dirt was shoveled out of the ~ettles in preparation 

1900. for another batch. The asphalt was hauled to Bakersfield 

The pioneer wo11k in the district was done by by big teams of _16 to 24 1?-orses and shipped east by ra.il. 

a company composed mainly . of Bakersfield There wa.s no local niarket. 

Of course the e'xpense ate up the profits, and the men 

men, among whom were Solomon Jewett, interested in the _venture began an effort to secure rail 

J. A. Blodgett, John I-Iambleton, Judge J. 0. traJ:!.sportation. H. F. Williams . * :* * took an interLovejoy, J. fl.· Woody, ·and W. P. Woods. est in the project and * * * succeeded in bringing 

This company located· some 2,000 acres of about an agreement.between Jewett & Blodgett and the 

land lying between the tar seeps at Old Sunset Southern ~acific Railroad by which the latter, in 1892, 

undertook .to bUild :;t railroad to McKittrick in two years 

and the site of the present town of Maricopa and one to Slmset i~ five years in return for assurances 

and in 1889 prepared to· drill for oil. The from Jewett & Blodgett th~t the traffic wpuld be sufficient 

following account of the operations carried· on to pay the operating expenses. As a part of the agreement 

before 1900 was written by Wallace Morgan, the Standard Asphalt Co. was organized, with Jewett & 

formedy editor of the Bakersfield Echo.I Blodgett and the railroad co.r:npany as equal owners, and 

all the asphalt properties between Sunset and MciGttrick 

It describes so 'well the details of· these. first were merged in the new concern. A little laterthera.ilroad 

efforts that it is here. given .in· his own words: offer~d an a~~ndment to the agreement to the effect that 

The ftrst well slink' on this. land and the first put down in it. would at once. construct the roa.d to McKittrick if the 

the Sunset field ·was drilled by William DeWitt, then of building of the Sunset line was waived. The: new ar~angeTulare and now justice of the peace at that place. ·DeWitt ~ent was accepted and the Mc!qttrick line was completed 

reached a depth of 300 feet on the SW; t SE. · t sec. 2, m 189Z. 

11-24, where he struck a strong flow of sli.lph~ water. 

This well was located, like most of the early wells, in a 

bed of brea at the very outcropping 'of the oil-bearing 

strata. Less than half a mile to the east were dn1led years 

later the productive wells of the Adeline Extension and 

had De Witt tried his fortunes a little farthe~ fro~ the 

hills the early history of the Sunset field might have been 

more rosy. However, when he struck the artesian flow of 

sulphur water the present Tulare judge pulled up stakes 

and moved his derrick to the SW. [NW.?J t sec. 21,11-23. 

about 5 .miles to the southeast, where he folmd anothe~ bed of brea and where he drilled a.well to a depth of 100 feet. 

The second venture was a little more encouraging, for a 

stratmn of heavy oil was found, and the thick, black semifluid .rose in the casing and oozed over the top. · 

1 'l'ho Morning Echo, vol. 31, No. 117, Dakorsficld, Cal'., Feb~ 28, 1911. 

A somewhat briefer account has boon published by Mr. Morgan in his 

book entitled History of Kern County, Cal., Los Angeles, Calif., Historical Rceord Co., 1914. 

* * * . The Standard Asphalt Co. took over the asphalt-making 

business of Jewett & Blodgett, but owing to the panic of 

18!)3 the venture did not pay, even with the better transportation facilities, and the partnership was diSsolved the 

railroad retaining the name of the company and t~kin~ the 

McKittrick end of the business, while Jewett & Blodgett 

went back to their old· firm title· and took the Sunset end 

as their share. In 1894 W. E. Youle, an oil-well driller from the Newhall 

and Puente fields, was placed in charge of the development 

work of Jewett & Blodgett at Sunset. * * * ' · Youle's first task was to pull the lost tools out of the old 

Barnard well on sec. 21, 11-23. Several wells were m·illed, 

but they were all too near the outcroppings, as it later 

developed, and their product was not sufficient even to 

supply oil for the flux needed in clarifying the natural 

·asphalt. ";l'hen the plan of sinking shafts to supply C:c 

. deficiency was tried. * * . * 
64. .THE SUNSET-MIDWAY OIL FIELD, ,CALIF.~PART I. 

There were difficulties, too, connected with the process 

of clarifying the natural asphalt in open kettles. In more 

ways than one it was like frying out lard, for a teaspoonful 

of ·water would make half a kettleful of hot asphalt boil 

over into the fire. Several plants were burned up in accidents like this. · 

In 1894 J.ewett & Blodgett had 16 wells at 

Old Sunset, the combined product from which 

amounted to about 30 barrels a day, the material varying from a heavy tar to. oil of 16 ° 

Baume. 

The following excellent description of the 

development of the Sunset. field in 1894 was 

written by Watts/ who visi'ted the region in 

that year for the State Mining Bure1;1u: 

Messrs. Jewett & Blodgett bored'two groups of wells in. 

the mesa lands of the Sunset oil district. One of these 

groups, '* * * "group 1," * * * ·is in sec. 21; the 

other,*** "group2,"isinsec.28.[T.l1N.,R.23 

W.]. In group 1 there are 13 wells, one of these being 

1,300 feet in depth, the remainder' varying from 80 to 500 · 

feet in depth. The 1,300-foot well yielded flowing water 

and much gas; the others yield a hea~y oil'by pumping. 

The 12 oil-producing wells are all situated within an area 

of about 400 feet in length and 30 feet in width. The 

1,300-foot well was bored a short distance in a northeasterly 

direction from the most northerly of the oil-yielding 

wells. The 12 oil wells yield altogether about 15 barrels 

of oil every 24ohours. The specific gravity of this ojl varies 

in the different wells from about 12° Baume to a heavy 

liquid asphaltum that requires to be heated by steam, 

which is forced to the bottom of the well, before the heavy 

oil ·can be ·pumped. Six of these are dry wells and are 

sunk to a depth of from 80 to 100 feet. The stratum yielding the greater portion of the heavy oil is about 35 feet in 

thickness. The other six. are drilled wells varying from 

150 to 500 feet in depth. All these wells are sunk to a sufficient depth to form reservoirs at the bottom capable of 

·storing the oil, which gathers during several days, for a few 

hours of pumping is sufficient to pump the oil accumulated 

during 24 hours. Each well is furnished with a pumping 

jack, consisting of knee and frame, which is securely 

anchored to the ground or mud sills. All these wells are 

pumped with lift pumps. 

* * * * The crude oil yields about 50 per cent of distillates, 

which have an average specific gravity of zoo Banme. 

The heat is increased toward the end of the process to 700° 

F., in order to expel the heavier distillates and make the 

·refined asphaltum hard .. Ids the intention of the Sunset 

Co. to treat these heavy distillates by fractional distillation, 

and at the time of the writer's visit these distillates were 

being stored in tanks for that purpose. 

*'. * * * · In 1892-93 Messrs. Jewett & Blodgett bored three wells 

on the mesa lands in ·sec. 28, at a point a little more than 

. a mile from Oil Wells, group 1, and in a southeasterly direc-

'tion therefrom. [These are the wells of "group 2."] 

* * . * . * 

1 Watts, W. L., Tho gas and oil yielding for~atio.ns of the ·Central 

Valley of California: California· State Mining Bur. Bull. 3, pp. 26-33, 

1894. . 

The oil yielded by the oil wells of group 2 is a dark-green 

oil and possesses a lowE;lr specific gravity than that yielded 

by the oil wells of group 1. 

One of the wells drilled . in the nineties i~ 

shown in Plate XXXII, A. 

·The operations about Old .Sunset were abandoned shortly after 1894, and. Jewett & Blod-· 

ge~t · moved their operations to Sunset, or 

Pione~r, as it was later known, in sec. 13, T. 

11 N., R. 24 W. In the later part of 1899 the 

Kern River field was d~scovered, and the success attained in• the relatively shallow wells 

there gave a great impulse to the search for 

oil in the surroundillg regions. Most of the 

land in the Sunset-Midway field was at this 

time located under the provisions of the placermining law, but owing to the distance from 

the railroad drilling ·was actually started on 

but· few· of the claims. In August, 1900,2 

there were between Old Sunset and the site of 

the present town of Maricopa 16 wells, which 

ranged in depth between 250 and 400 'feet and 

yielded between 10 and 25 barrels of oil of 11° 

.Baume. Another well875 feet deep had been 

drilled in sec. 18, T. 11 N., R. 23· W., east of 

the main group. Besides the wells of Jewett 

& Blodgett the only other productive well in 

the Sunset field at this date was one belonging 

to the Monarch Oil .Co., in the NW. ! sec. 2, 

T. 11 N., R. 24 W., which flowed and was said 

to yioeld about 75 barrels of oil a d,ay. 

About this time an agreement was reached 

with the Santa Fe Railway to ht~ild a line from. 

Bakersfield to Sunset, but before construction 

had been started an arrangement had been 

made between the Santa Fe and the Southern 

Pacific concerning joint ownership of feeder 

lines from points common to the two roads. 

The Sunset Railroad was to have been completed in .1901 but was not actually finished 

until 1'902. This delay in the completion of 

the rmid had a serious e:«ect on the. field, for 

upon the aimouncement that a railroaq was to 

be built to Sunset that. field became the scene 

of great activity, ·all vacant land about Sunset 

and in what is now the Midway field was 

located, and drilling was started on .many of 

the sections. Most of the wells about Sunset 

got small quantities of petroleum, but by the 

ti~e the railroad was completed and adequate 

means for shipping ~he oil were provided the 

2 Watts, w: L., Oil and gas yielding formations of California: Cali-

. fornia State Min. Bur. Bull. 19, p. 123, 1900. 
U . S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XXXII 

This well furnished oil for the old refinery shown in Plate XIII, A. 

B. DERRICK AND GAS TRAP IN MARICOPA FLAT. 

The derrick (at the left) is more than 100 feet high. Note the difference between it and the one shown in A. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XXXill 

A. SUNSET OIL FIELD IN OCTOBER, 1908. 

Looking northeast, cast, and southeast from Occidental property 1 mile northwest of Maricopa. Photograph by Ralph Arnold. 

B . MARICOPA FLAT, SUNSET OIL FIELD, IN 1914. 

Looking northward from center of sec. 5, T. ll N., R. 23 "\V. The low hill in the center is the topographic expression of the Thirty-five anticline. Wells in sec. 4, T. 11 N., R. 23 W .. arc shown at the extreme right. 
I I ~ 

PETROLEUM. 65 

price for oil had dropped so low that few of the 

companies coul~ live. . 

1'he drop in the price of oil affected the 

Midway field eve'l more seriously, for i.t w~ 

at that time without proper transportation 

facilities, and alllu.:mber, machinery, and f'iel 

. had to be hauled by team either from Sunset 

or from McKittrick. At first drinking and 

even drilling water had to be· hauled from the 

:Miller & Lux well far out in San Joaquin Valley'. The diffi.cu lties ·under which the first 

operations were conducted here are described 

as follows in an article published in the Maricopa Oil News in July, .1 91~: 

Tho first drilling in the [Midway] field was by the 

Oregon 1\Jidwn.y, on sec. 4, 32-23, with a patent rig. 

· Three wells were drilled, but with the rig 600 feet was 

tho greatest depth to be reached. A standard rig was 

secured and a hole drilled to l ,000 feet. The drilling 

water had to be hauled by team from the Miller & Lux 

hog ranch. In 1901 the Producers' Guaranty d'o., w!::rich 

guaranteed to strike oil in two years or refund the amount 

paid for Atock, began drilling. On its fi.rst well the drillers 

we1·o paid $5 per foot, .the company furnishing all machinery, supplies, water, and fuel. On Ff;lbruary 26, 1901, 

tho machinery was hauled across the bed of Buena Vista 

Lake, which was then dry, no water having been in it for 

three years. On Mu.y 1, 1901, the first oil was struck, at 

1,407 feet, the casing being 7ft- inches. For this work the 

water cost $1.25 per barrel delivered at the well. After 

the water was delivered the company .had to permit the 

10-mule teams used to haul it to drinl~ from it.·· They used 

about half the water hauled. Fuel oil was secured from 

Sunset., it requiring four days to bring a tank of oil. It 

cost $2.90 per barrel, and hauling cost $15 per day for the 

team. 

On May 15, 1901, the first Midway oil sold 'was from the 

Producers' Guaranty to the Oregon Midway f~r fuel, 

they having beim buying from MciGttrick. Among other 

drilling companies was the C. C. M. Oil Co., the Bay City, 

the Mascot, the Judge, the Crump, and the Pittsburg. 

The Producers' Gtiaranty had a production of 250 l;>arrels 

per day, though it was pumping but 12 hours a day. In 

· Hl02 Buena Vista Lake filled up and the Producers' 

Guaranty Co.'s four wells had water trouble. This disappeared two years later, when the lake went down. In 

Hl03 the oil industry in the Midway "blew up," as there 

was no way to ship it, and Kern River oil was selling at 10 

cents per barrel. 'l'his continued until 1907. In that 

year Boust and·others formed the· Knob Hill Co., and also 

leased land to other companies, which began work and are 

now among the producers. 

In 1907, with the return of adequate prices 

for oil, the Sunset-Midway field started its 

tremendous growth that has continued up to 

the present time. ·csee ~I. XXXIII.) Prospecting gradually left the foothills along which 

it had hugged, spread boldly out over Midway 

109288°-19--5 

Valley and the Buena Vista Hills, .and in 

1 Q 10 entered the Elk IIills. During this time 

t~e field passed through the pe.riod of speculation co~on I to most new mining camps.· 

Titles to mining cl~ims changed hands many 

times in a few weeks, each time at an jncrease 

in price. The price for claims covering tracts 

several miles from any producing well increased 

from a few dollars to $i,OOO or more an aore, 

and those holding a clear ti tie to the land were 

able to command even higher prices. The 

maximum price attained was reached in 1910, 

just after the famous. Lakeview No. 1 gusher 

started flowing, when $200,000 is reported to 

have been offered and refused for a tract of 20 

acres lying close to that well. 

Prior to 1909 tlie producing wells that had 

been drilled furnished oil by pumping or flowed 

moderately, but none had produced more . 

than a few hundred bt.t.rrels a day. In November, 1909, the Chanslor-Canfield Midway Oil 

Co. brought in a well near Fellows that flowed 

at a rate of about 2,000 barrels daily. This 

was the first of the big wells of' the field.· 

During the following year more· ~han 25 

flowing wells with an initial production of 

1,000 barrels or more had been brought in, and 

up to the present time (1'916) over 100 such 

gushers have been drilled. 

The most famous of these wells was the first 

Lakeview gusher, in sec. 25, T. 12 N., R. 24 

W., which came in March ·14, 1910, and' the 

following day produced approximately 18,000 

barrels of oil. Within a few days the well was 

far beyond control. It continued to flow for 

18 months, finally stopping September 9, 

'1911, after it had produced over 8,000,000 

barrels of oil, about 6,000,000 barrels of which 

had been saved. The daily production of the 

well varied greatly, reaching a maximum of 

about 65,000 barrels. At first the product 

was practically clear oil having a gravity of 

18° to 21° Baume, but in a few weeks water 

and emulsion appeared and gradually increased in amount, forming some 60 per cent 

of the daily product on January 1, 1911. 

The pipe lines l~ading from the field were 

inadequate to carry the product of the field 

while the Lakeview well was flowing, and much 

of the oil from that well was stored in earthen 

sumps constructed hastily by throwing dams 

across l?mall canyons in the foothills. Het::e 

the oil stood for weeks or months exposed to. 
66 . THE SUNSET-MID~AY OIL FIELD, CALIF.:_PART I. 

the sun; and ~hen finally m~rk~ted it had lost and 6 of the same township. In the north end 

most. of its l~ghter constituents~ of the Buena Vista Hills the Standard Oil Co. 

About tl,lissame tjine·a group of flowillg wells obtained big gas wells in secs>22 and 26, T. 31 

in the North M;i,dway field was attracting much S., R. 23 E., the first of which ·was brought 

attention. The first of these wells was that of in October 11, 1909. At first the g'as found 

the ·Mays_ Oil ·co. (now the Consolidated Mu- but little utilization oth,er · than to supply 

tual), in ~ec. 30, ~· 31 S., R. 23 E., which started fuel for drilling operations on near-by propto flow on March 7; 19iO, at a .rate of over erties, but in 1910 the Standard Oil Co.'started 

10,000 barrels a d~y. In close succession f~l-· to use it in its. pumping station in Mid~ay. 

lowed the wells of the St. Lawrence Oil Co.~ Later the California Natural Gas Co. laid a 

. those of the Pioneer Midway Oil Co. (now the line to the Elk Hills to serve drilling companies 

Associated Oil.Co.); well No.2 of the Chanslor-· there and finally extended its lines to Bakers-· 

Canfield Midway Oil Co., in ·sec. 36, T.: 31 S., field, first serving that place on December·29, 

R. 22 E.; wells of the Mammoth and Eagle 1911. As early as 1910 the project of piping 

companies, in sec. 31, T. 31 S., R. 23 E., qf the gas to Los Angeles was considered, but it was 

. Midway Premier Oil Co., in sec. 5, T. 32 S., R.· not until November, 1911, that the Midway 

23 E., of the Midway Premier Oil Co., in sec. 5 Gas Co. was incorporated for the purpose of 

T. 32 S., R.· 23 E., and of the United Oil Co.,in ' constructing the necessary transmission main. 

seq. 6, T. 32 S., R. 23 E. · The greatest of these In September, 1912, a 12-inch line 111 miles 

North Midway ·wells was No. 79 of the Ameri- long was completed to West Glendale, near Los . 

can Oilfields Co.; in sec. 36, T. 31 8., R. 22 E., Aiigeles, and service was started April28, 1913. 

which carrie in April 3, 1910, making 400 bar- Since 1911 .all parts of the field have shown 

rels of oil the first day. The,production gradu- steady growth, the greatest amotint being in the 

ally increas~d until in ·J_"une it was ~aking over. Buena Vista Hills, in North Midway, and in 

1,000_:· 'barrels of qil .. Late in July it broke Maricopa Flat .. The last-named area attracted 

loose and for a time produced at a rate of over much attention during' 1912, 1913, and 1914, 

20,00,Q .. b~rrels daily.: Aftera couple of months having a group of flowing wells, among which 

the tremendous ga.s pressure was ~xhausted were those of the Obispo, Spreckels, Miqcene, 

and. the production dropped to ~rate betwe,en Midland Oilfields, and General Petroleum com1,000 and. 2,000 barrels daily, which w~s main- panies. The most spectacular of these wells 

tain.~d·for.r~wre than three years. · was that of the Lakeview No.2 Oil Co.; which' 

4notger group o'f floffi?g:wells was obtained. came in May 10, 1914. Like the old Lakeview 

ear~y in 1910 by t~e St~d~rd Oil Co. along the· well, this well baffled the efforts of the· comfoot}4lls of .the main range in sec. 30, T. 32 S., pany to control it, and soon the casing had been 

R. 24 E.· These wells flowed under perfect con- cut away and a crater-like hole about 60 feet 

trol, two. of, them for a time individually pro- across excavated about the mouth of the 

clueing as much _as, ·7,500 to 10,000 barrels well. The w~ll flowed until October 25, 1914, 

daily. · . and the total amount of oil produced up to 

In. the ~eantime· drilling in the Buena Vista that time was roughly estimated at ·about 

Hills,l.1ad met with success. The pion~er well 6,000,000 barrels .. The rate of production 

here.was that·drilled in sec. 10, T~ 32 S., R. 24 varied greatly, butthewellissaid to have made 

E., by. the. Honolulu Consolidated Oil·. Co., as much as 50,000 ·barrels in ·a day. Like the 

which in_1909 obtained .a s·trong"'flow of gas at old Lakeview, and indeed like most of the big 

a depth of a little more than 1,600 feet. The flowing wells, this well produced at first praccompany was then entirely· .unprepared to tically clear oil, but water and emulsion soon 

handle gas under such heavy pressure, and the appeared and, increasing in amount, came to 

well ran wild for abo:ut two months. Eventu .. form as much as 80 per cent of the total 

ally it was deepened rriore than·2,500. feet, and product. PRODUCTION. early in 1910'it produced light-gravity oil flow- . 

ing at a rate of 2,000 ori3,000 barrels daily. 

Later in the same. year 'the company ob-

. tained large flows of gas from wells in sees. 4 

The following table ha~ been prepared from 

figures furnished to the Survey by the operating 

companies. (See alsO' Pl. XXXIV.) 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XXXIV 

150 

140 

150-,_000 l------ll----------1-----l------ll------ll-----l-----t----t-----t-----f----____.JI---~f'v..--+-----+-----+------t 

~I \ 1~ooo~----~----~----~----~----~----+-----+-----+-----+-----4-----~M~v--~,--~~----~~--~ 

300 

130 260 130,000_r-----+------~-----r-----r-----+-----;-------~------+-------+-------~------r~-~~------;-----~--~ 

120 

110 

-~ .~ r.:l-

~ E-1 ~ 

z < 0 100 ·c::Q 

::s z ::r: 

0 - r:i ~ 0- 90 i3: 

r.:l r.:l E-1 c.,:, 

ll. 

~ ~ r.:l ::s ~0 > 0 

0 < 

.j ~ 

0 

r.:l z ~- 70 0 

~ § 

:::> ~ 0 

0 

~ 60 ~ 

~~ ll. 

p ~~ 

I~ ...:I 

-

< 0 

120,000~----r-----r-----~----~----~----+-----+-----+-----+-----~--~~~----H,----~----~----_, 

""~ \ A (\ 

240 

_220· 110,000 

; 

~ 

~ 

< c::Q 100,000 

z 

-

0 

...:I 

r.:l 

rz 90,000 

~ 

0 

·z 

0 

E= 80,000 0 

:::> 

0 

0 

~ 

~ 70,000 

~ 

< 0 

ril 

c.,:, 60,000 

~ . r.:l 

> < 

200 

180 

160· 

' 

140 

l j\ ('J v J ~" 

J20 

fr \ .I•~ daily I>roduction of field 

v \ 

,\ A 

60 

40 

30 

.20 

10 20 

100 50,000 

80 

v \ljv v- \ 

40,000 1---tt----t------t--Q ----+----1----+-------+-----f /J-t---;--r.-, --1\ -1------+----+------+h~.;/~'\.---== 1\--t------t-----t 

I \ /' ~ '. 

J 1\. I~ l / ~~~~~r\ ,

1/11 : \; I II r, "' 

I - I\ ~ I I I I I ll l ~ "I I ·ao,ooo t--t--~r--t----+----+----+---+-p..l--\---=--+----,~rl-+--~~-+t-T-++-+-..._-+tH--+.--l-\:---r-+--!-+--+----+-----r----~---;-1 

I N 'W\11 v Al 11 \1 

1

1t /\ 

1

\

1

•\ I \I I I \ l I I .... _, ,, 1 \ ,, I :\ \ A ~ I 

r\ I I I ,, " " I,-' v II I I I II " ~I j v v il v v v \ I \ I \I\ j I /1 '\ I \ 

A r !! 1 ' 1 I ," : • \ I \ Ll r \l 1LL 

V-\j V \ y~ .~ /' ~ ~~ I '~ \ ,. r; \ I ~ A : \''\ .., 11 ' ' I ;;q\ ,' \ I\ I I I I \J I f\ A ,.. I \I ~~ : ~ u I v \.. l I I II I" ~ 

:\ f, ( V Number of wells completed each month h / \j \ J) 10,000t-----l----~t--r~-t-----l~~---t--~~~-7--Tt----t---~t-----+----t-------~-~~-!rr~~,~-----r~---; 

h I f'-,r f\ ,J \} 1V' v'\,'" I v ~'J~ __ ,~77 

60 

40 20,000 ~ 

--- -----~~------

1903 1904 1905 1906 _1907 1908 1909 1910 1911 . 1912 1913 1914 1915 1916 1917 

CURVES SHOWING PRODUCTION OF SUNSET-MIDWAY FIELD. 
PETROLEUM. 67 

Oil marketed in the :Midway and Sunset fields, Cal., 1900- Valley Gas 'Co.-Line from Midway to Bakersfield, a 

· 1918, in barrels. distance of about 40 miles. Pipe of different sizes. 

Year. Sunset. Midway. Total. 

1900 ............ a 12,000 ············ 12,000 

1901 ............ 189,000 4,.000 193,000 

1902 ............ 133,000 5,000 138,000 

1903 ............ 181,000 a 5, 000 186,000 

1904 ..... : ...... a276, 000 as, 000 284,000 

1905 ..... ·.···· .. 317,000 13,000 330,000 

1906 ............ 563,000 (b) 563,000 

1907 ····· ....... 567,000 134,000 701,000 

1908 ............ 1,556,000 410,000 1,966,000 

1909 ............ 1, 713,000 2,095,000 3,808,000 

1910 ............ c 7, 157, 000 10,436,000 17,593,000 

1911 ............ c 6, 350,000 21,196,000 27,546,000 

1912 ............ c 6, 509,000 23,928,000 30,437,000 

1913 ............ 6,212,000 32,349,000 38,561,000 

1914 ............ 9,242,000 37,863,000 47,105,000 

1915 ............ 8,731,000 29,930,000 38,661,000 

1916 ............ 7,358,000 31,840,000 39,198,000 

1917 ............ 6,681,000 28,830,000 35,511,000 

1918 ........... 7,432,000 3~,517,000 39,949,000 

-- --:-*-· 

............ ············ 322,742,000 

u Estimated. 

b Included in Sunset field. c Includes some from Midway field. 

PIPE LINES. 

Most of the oil from the Sunset-Midway field 

is delivered to· the large pipe-line companies 

and by them pumped to tidewater .. The lines 

leading from the field are described below .. 

Oil~ LlNES. 

Standard Oil·Co.-Two 8-inch Jines 32 miles long from 

Midway to Kern River, with 14 miles of 12~inch loop. At 

Kern River these lines join the main valley system of the 

company~ that runs to Point Richmond, on San Francisco 

Bay. Capacity about 65,000 barrels daily. 

Associated Pipe Line Co.-One 8-inch line 279 miles long 

from Sunset through the Midway field to San Francisco 

Bay. Capacity about 26,000 barrels' daily. 

Producers Transportation Co.-One 8-inch line 50 niiles 

long from Sunset through the :Midway field to Junction 

station, at the north end of the Temblor Range. Capacity 

about 30,000 barrels. At Junction this line meets the 

8-inch lines from Coalinga and Lost Hills, and the oil is 

pumped through two 8-inch lines 74 miles westward to 

Port San Luis, which is on the coast about halfway frqm 

San Francisco to Los Angeles. 

General Pipe L{ne Co.-One 8-inch line from Midway to 

I. .. os Angeles, a distance of 156 miles. Estimated daily 

capacity of line about 25,000 barrels. A branch· 8-inch 

line extends from Lebec, in the Tehachapi Mountains, 52 

miles eastward to :Mohave, where the oil is topped before 

shipping it by rail. GAS LINES. 

:Mid'Way Gas Co.-One 12-inch gas line from Midway to 

West Glendale, near J ... os Angeles, a distance of about 115 

miles. In 1915 only about 15,000,000 cubic feet of gas was 

sent through the line daily, but it is said that 35,000,000 

cubic feet of gas has been delivered in a day. 

Capacity about 1,800,000 cubic feet a day on a 4-ounce base. 

WATER SUPPLY. 1 

The east flank of the Temblor Range contains 

no perennial streams and very few springs that 

flow, except during the wet season. Moreover, 

the ground water throughout "the foothills is 

not potable, and all the water used in the 

Sunset-Midway field for domestic purposes and 

much of that for boiler supply and drilling purposes is piped in from sources outside the productive field·. . 

The lack of a sufficient water supply severely 

handicapped the first operators in the field, 

and it was not until the Western Water Co. had 

completed its system that the field had an adequate supply. The first operators in the Sunset field were dependent for boiler and drilling. 

water upon sulphur-water wells, chietly those 

in sees. 12 ·and 13, T .. 11 N., R. _24 W., and 

before the railroad was completed drinking 

water ·was hauled by wagon from springs in the 

west end of the San ·Emigdio Mountains. It is , 

said that this water costs 10 cents a barrel at 

the springs and tliat it ~oqk a full day to make 

~ round ·trip from Sunset.. The Midway field 

was hardly more fortunate, as. it was dependent 

upon the small. supply furnished .by the 

Chanslor-Qanfield Mid'o/ay Oil . Co. and the 

Stratton Water Co.' Drinking wat~r .for use 

in many of the camps and. in the' to.wns was 

hauled by the Sunset Railroad in · ~ank cars 

from Kern River, on the east side of San 

Joaquin Valley. • 

In i914 the field was supplied from a number 

of sources at an average price pf about 3 cents 

a barrel. The chief supply is that furnished 

by the Western Water Co. from shallow wells 

at the north end of Buena Vista Lake. This 

water is used throughout the field for domestic . 

and boiler water. , 

The Chanslor-Canfield Midway Oil Co. pipes 

water for its own use and for the use of some 

of the companies in the north end .of the Midway field from Santa Maria Valley, west of 

McKittrick. Thi~ was one of the first supplies 

developed for use i~ the Midway field, and in 

the early days the water was sold for 21 cents 

a· barrel. The water is used both for domestic 

purposes and in the boilers. 

1 Analyses and a discussion of representative waters used for industrial 

purposes are given in Part II of this report (Prof. Paper 117, Table 17, 

p. 78). . 
68 THE SUNSET-1\HDWAY OIL FIELD, CALIF.-PART I. 

The Standard Oil Co. pipes water to its ~ontained in the lands belonging to th.e Govcamps from the east side of San Joaquin Valley. ernment. · 

With the possible exception of the water from Wheri. oil was first discovered in the Sunsetthe W agy ranch an9- that from Santiago Creek Midway region most of the land was still a 

used·at the Westerp. Mifl:erals camp this is the part of the public domain, and application for" 

·beet water in the field. · title to it was mad'e under the laws governing 

Sufficient w~ter for domestic use in ·Maricopa the disposal of the public lands. Not only 

is piped from the.Wagy ranch, in sec.12, T.. 9 were many tra:cts located according to the 

·N., R. 24 W. The water here issued from regulations prescribed by the mining laws, 

Tertiary sedinientary beds in the bottom of but application was made for these same tracts · 

Ballinger Canyon. . . under the laws providing for the disposal of 

The camp of the Western Minerals Co. near agricultural lands. Most of the land in the 

.·Old Sunset is supplied with splendid water Sunset-Midway oil field is clearly without value 

·from springs in a faulted area on Santiago Creek for fs;trming, and the sole purpose of n1ost of the 

in the 'west end of the San Emigdio grant. agricultural entries was to enable the applicants 

The water issues from early Tertiary sedimen-. to obtain valuable deposits of oil and gas. . · 

tary beds close to the granitic. rocks, with In order 'that the prospector might be prowhich they are in fault contact. tected as thoroughly as possible from these 

Water so heavily .charged with mineral salts unnecessary ~onflicts, the lands thought to be 

as to be useless for domestic purposes is fur- valuable for petroleum were withdrawn from 

nished as boiler and drilling water by a number agricultural entry on September 14, 1908. (See 

of wells.· The water ·is of varied character, Pl. XXXV.) ·Although this withdrawal was 

some of it highly charged with sulph'tlr or hy- of great setvice· in reducing the number of 

drogen sulphide, and some of it, chiefly that unnecessary conflicts and· in protecting the 

from the deeper wells, saline. The principal prospector who was operating in good faith, the 

companies furnishing water of this type are fact, which had long been known, that. the 

the August Water Co., from wells·in sec. 35, T. placer-mining law is a sad misfit as applied to 

32-S., R. 23 E., and sec. 31, T. 32 S., R, 24 E.;· oil and gas lands, became :ipcreasingly apparthe Stratton Water Co., from wells in sec. 7, T. ent. This law was framed to apply to lands 

32 S., R. 23 E.; and the Northern Oil Co., from containing solid minerals that lay at or close 

wells in sec. 12, T. 11 N., R. 24 W. . to the surface, and ,the attempt to apply 

. The waters of Buena Vista Lake are con- such a law to lands containing oil and gas that " 

trolled by a large land company and used for lay many hundred feet below the sunface led 

irrigation in the central part of San Joaquin to many di#iculties, not the least of which was 

Valley. Only a single company, the Honolulu the ·necessity for making a discovery befo~e 

Consolidated, uses this water in the oil field. paten~ could be granted. This requi:t;"ement of 

This company maintains a pumping station in an actual discovery of mineral upon the land 

sec. 1, T. 32 S., R. 24 E., from which it pumps made· it n·ecessary for the applicant to drill 

drilling and boiler water to its pro.perties iii upon land to which he had. no legal title nor 

Buena Vista Hills. could. have until his well obtained oil or gas. 

In many places rival claimants drilled wells 

upon the same tract, the first to obtain oil or 

Ever since the d-iscovery of oil in the Midway gas getting title to the land .. Naturally the 

field, but especially during the period of rapid necessity for making the discovery as soon as 

·development from 1900 to 1910, . numerous possible under such conditions led to hurried 

conflicts have arisen between different persons and reckless drilling, ·and wells were put down 

. who had one or another sort of claim upon the without proper regard for the protection of 

same tract of land. Such conflicts inevitably the oil sands. 

WITHDRAWALS. 

arise in any new mining district, but they have Bad as such a state of affairs is, the existing 

been especially num~rous and especially trou- laws and customs foster a condition that is 

blesome in the oil fields of the public-land even more regrettable, for they make it practiStates, on account of the lack of satisfactory I cally impossible to regulate the production of 

la~s governing the disposition of oil and gas oil in acco,rdance with the demand existing for 
U. S. GEOLOGICAL SURVEY 

I -----·*·-·-- Railroad grant line, 20-mile limit 

------+--·-- Railroad indemnity line, 30-mile limit 

PROFESSIONAL PAPER 116 PLATE XXXV 

EXPLANATION 

hLl Outstanding withdrawals November I, 1915 

Ll.__j ~ From Geological. 

Survey records 

jfi..--nl Naval Petroleum Reserves Nos. 1 and 2 

• LandS patented to railroads 

Larrds patented_ otherthan t~10seto railroads 

~ Lands covered by ininer~l applications L=--_j for patent 

1.1 

~ 

Lands cove_red by nonmineral entries or selectiOns 

5 0 5 

From Land Office records, 

compiled to 

Aprill.l.915,by 

J.H.G. vvolf, of 

the Bureau of 

Mines 

19 

MAP SHOWING PETROLEUM WITHDRAWALS AND N-AVAL PETROLEUM RESERVES IN AREA COVERED BY GEOLOGIC MAP (PL. II). 
PETROLEUM. 69 

it. As a result 'the fields have suffered many 

times from a tremendous overproduction, necessitating· the storage of light-gravity oil in 

earthen sumps exposed to the sun, so that by 

the time the oil was marketed many of the 

lighter and valuable constituents had been lost 

by evaporation. 

'In order thoroughly to understand the 

reasons for this state of affairs the great 

difference between deposits of solid minerals 

and those of fluids such as oil and gas must be 

appreciated. In deposits of solid minerals a 

certain definite an1ount of the minerals is contained in a certain definite place and will renlain there until it is mined out. On the other 

hand, no definite an16unt of oil or gas is attached to any particulru~ tract 'of land, and even 

though no attempt ~is made to obtain the 9il 

underlying a certain"area by drilling wells upon 

that area itself, part of the oil lying beneath the 

surface of this tract or even, if the tract is 

small, practically all of it may be drained out 

by wells drilled upon adjoining lands; or such 

wells may so alter the normal conditions, as 

for example by letting water into the oil 

sands; that wells drilled later upon the tract 

itself can not obtain oil at a commercial profit. 

Moreover, the first w.ell drilled into the oil 

sand has a gi·eat advantage over the near-by 

wells drilled later, for it gets the full benefit 

of the initial gas pressure, and in consequence its 

production during its early life is greater than 

' the initial production of the later wells. Also 

it is evident that this first well establishes 

lines of drainage in the oil sand along which oil 

moves· more readily than it does in other directions, for even though several wells are drilled 

on a tract of land, the first one will continue to 

drain a large area, part of which lies much 

closer to the later wells than to the original 

well. Commonly, therefore, other things being 

equal, the production of this first well continues 

to be greater than that of any of the later wells. 

· Thus it is apparent that a tract, particularly'. 

a· small tract, of land lying within a producing 

oil field can not be consider.ed to have a constant potential value as oil land, and the safest 

way to obtain the n1a..~imum yield of petroleum 

is to exhaust the oil sand as quickly as possible 

once it has been tapped. 

Another factor that makes for the rapid developinent of an oil field, or indeed of any mineral deposit, is the interest upon the capital 

invested. Were the market price of the ·product constant, the most profitable ·method of 

handling a property would be the one that, 

without· unduly increasing the cost of extraction, exhausts the property soonest. Of course, 

many conditions must be considered in determining the rate at which the property is to be 

developed, and ,a illce adjustment must be 

effected between interest on capital invested, 

on the one hand, and the market price or the 

demand for the product and the increased cost 

of production that attends an increase in the 

rate of production, on the other. With deposits of solid minerals this adjustment .can be 

made with relative ease; for, as a rule, no irreparable injury results from closing down temporarily when the demand for the .product is 

less than the supply. In an oil field, however, 

such an adjustment can not be made easily, 

for the policy adopted by one operator must of 

necessity influence that of his neighbor, anq, in 

many fields instead of temporarily closing down 

a property during periods of overproduction 

and consequent depression of price it is necessary to continue drilling new wells. 

The conditions under which one producer is 

operating-perhaps the terms of his lease,- perhaps his need for oil for his ow:q. use in other 

business, or to fill a contract-may make it 

~ecessary that he increase his production by 

drilling a new well. Now, in drilling a tract of 

!'and it is an almost universal custom to place 

the first wells close along the boundary of the 

property, with the avowed intention of drawing 

oil from as much of the neighbo~ing land as 

possible. 'Where such a line well is drilled the 

owners o~ the adjoining property must either 

themselves drill a well to offset that drilled ~y 

their neighbors ~r sit idly by and allow oil ·to 

be drained from beneath their land. Should 

the first well be drilled in the corner of a tract 

where four properties jqin, three offsetting 

wells may be. necessary, all of which may be 

drilled most unwillingly by the owners, and all 

further flooding an already overloaded market. 

Clearly, the law that cuts the field up into smaJ.l 

units and then forces production upon, each of 

these' units is not a law that fosters conservation. 

Inview of these conditions,. and also be.cause 

of the advisability of reserving for the·N avy an 

adequate supply of fuel oil, the Geological Survey recomri:l.ended that certain tracts, which 
70 THE SUNSET-MIDWAY OIL FIELD . . . ' CALIF.-PART ·I. 

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

inclu?-ed practi~ally~the·~ whole of .the SunsetMidway :fie~,d, be withdi:awn f:.r;om ~ntry,' and o~ 

Septem her· ~7, 1909, the Secretary of the. In:-

terior issu~d an ?rde~ .. providing that · · . 

· In aid of ·proposed legislation affecting the use and disposition of the petr9leum deposits on the public domain. 

all public lands in the. accompanying lists are hereby tern~ 

porarily withdrawn_from·an forlns of location, selection. 

filing, entry, or disposal under the mineral or nonmineral 

public-land laws. 

oyerpro9.'!lctiori thr.eatened. Had it not been 

for the .r:etarding effect they had, it ·is probable 

that in 1910. the market would have been so 

flooded and the price of oil so reduced that 

many of the companies now operating wo.uld 

,have been forced out of existence. · 

ORIGIN OF THE PETROLEUM. 

The chief reservoirs of petroleum in the 

·Sunset-Midway district are the fee~ly consoliSince this. first departmental withdrawal was dated sandy beds of the McKittrick group, but 

mad.e several Executive orders have been issued the petroleum is believed to have originated 

providing for the withdrawal of (!ertain areas not in these beds but in the fine-grained beds 

in the Sunset-Midway field and for the restora- of organic origin that make up so large a part 

tion to entry of areas which the field· examina- ·of the Maricopa shale and of the upper p·ortion 

tion by the GeologicalSuryey showed to be not of the Vaqueros formation in certain parts of 

oil :hearing. . the region. These fine-grained beds are chiefly 

A full discussion of the objects f~r which the the so-ca~ed diatomaceous· shales, which ~re 

withdr~wals of land in the California field were composed In large part of theremains of minute 

made and a history of these withdrawals would plants and animals-diatoms and foraminibe hardly appropriate here, even if space would fers-and it is from the decomposition and 

permit. One who is interested in this phase of alteration of these organisms that the petroleum 

the question will p.nd an excellent account in a now found in the Sunset-Midway :field results. 

report by BalU · In parts of the region the organic material conAs yet (191S).no satisfactory method for the ta.ined originally in the fine-grained beds apdisposal of oil and gas upon the public lands has pears to be not so much the remains of diatoms 

·been evolved. by Cong1;ess, and the ultimate as of larger 'terrestrial vegetation,· and it is 

purpose of the withdrawals has not been probable that part of the petroleum has been 

achieved. Those withdrawals haye, .ho~ev.er, formed by the altera;tion of this coarser vegetal 

accomplishe.d two -~ery defin.ite things neither material. But in any case· it seems clear that 

of which entered into the. calcul,ations of those. the. ultimate source· qf the petroleum is the 

who had to dq wi~h or~~ring the wi;thdra~al~~ organic material originally contained in these 

One_. of these. results is so obvious as ·to be ap- beds. · 

preciated .by .ev.e:ry<;me, but 'the .other js more There' is nothing ne~ · or· startling in the 

obscure~: In t4~ :first. place the withdr~'f~l of theory that the petroleum in· California has 

September, 1~0~, was .. made so abruptly t)l.~t been ·formed from the organic material con-

'"it kl;locked .t¥e breath, f~r the.momen~, from · tain·ed in the diatomaceous shales, for those 

the California oil, industry." .. The. validity of shales hav·e long ·been considered the source of 

the. withdrawal was questioned by many, and the oil. · The reasons that they have been· so 

work was continued.despite it.· Litigation.'that regarded ·have recently been discussed someappears _endless has arisen and bids fair to out- what· in detail,2 and anyone particularly inlive .the :field itself. Many ope:.r;ators who ~ith terested in this phase of the subject is referred 

the best of intentions started development work to that report, for the discussion will not be 

on the public land$ in the oil field have found repeated here-in detail. The chief reasons suptheir ventures anything but profitable. But, porting the belief that· the oil has had such an 

on the otl;ter hand, though the effect of the with- origin are, however, about as follows: · 

drawal on individuals has thus .been harsh and In the first place; the rocks in th~ vicinity of 

for many almost ruinous, the effect on the oil the oil field are sedimentary, igneous rocks beindustry of California as a whole has been dis- ing notably few, and, unless one holds to the 

tinctly bene:fi~ial, for these orders more than any belief that the oil has migrated from some 

other one thing served to keep down excessive source deep within the earth-and of such amidrilling during the boom days ~h~n a great gration there is not the least bit of evidence in 2 Anderson, Robert, and Pack, R. W., Geology andoilresources ofth~ 

· 1 Ball, M. W., Petroleum withdrawals and restorations affecting the west border of the San Joaquin Valley north of Coalinga, Calif.: u.S. 

public domain: U. S. Geol. Survey Bull. 623, 1916. Geol. Survey Bull. 603, pp. 194-203, 1915. 
PETROLEUM~ 71 

the Sunset-Midway region-he is forced to the 

conclusion that the oil n1ust have originated 

in· the sedilnentary rocks ··then1selves. The 

diatmnaceous shales ·and the shales that contain a large a1no'unt_of carbonaceous matter are 

believ-ed to be the beds in which the oil originated, because these beds are the only ones that 

contain or have contained material fron1 which 

it is at all r~asonabl~ to expect that oil 'would 

form. There are no conside,rable amounts of 

limestone in the section, and the coarse detrital 

beds co.mposed wholly of fragments of rocks of 

v-arious types are hardly to be considered' as a 

source of oil. Moreover, the field evidence 

supports the th~ory that the diatomaceous 

~hales, or shales of sim_il~ type, are the beds 

in which the oil originated, for not only do 

practically all the oil fields in California lie in 

areas that contain considerable amounts of 

shale of this type, but the oil sands'within the 

fields exhibit a notable tendency to lie either 

within the diatomaceous shale formations or 

inunediately adjacent to th~. · Although_the 

sedimentary beds in the oil field may be n1any 

thousands of feet thick, the oil sands are· clustered in and about the relatively small part of 

the section occupied by the shale, and thousands of feet of beds that.underlie and overlie 

'the share are, where not in contact wi.th -the 

shale, barren of oil. · · · · · 

Finally, it is of ·intei;est to note that at tlie 

south end of San J·oaquin Valley the diatonlaceous shale app~m:s to be f~jrly pure_:_that is, 

the proportion <?f it cmnposed of ~J:e !emains 

of these n1inute prganisn1s is large-and also 

that the for1nation is about' as thick here as it 

is in any other part of California. For it. is jus't 

here tha~ the largest ~d most productive oil 

field in the S'tate is located. · 

FACTORS INFLUENCING ACCUMULATION OF THE 

OIL. 

In most regibns where oil is found it is difficult to reach any ''ery definite co~~lusion as to 

the exf,Lct n1aterial from which the oil was 

forn1ed, or to determjne precisely . how or 

why the oil has concentrated in certain areas 

in sufftcien t an1oun ts to f01;n1· commercially 

v-aluable "po9ls." Altho';Igh, as has bee~ 

shown in the preceding section, the fact appears 

to be established that the oil in the California 

fields has o.rigina ted frmn the organic n1a terial 

contained in the diaton1aceous shales, the precise way in which the oil has concentrate~, or, 

indeed, the reasons why. It, has qoricentrate<;l at 

all, ru:e. no more easy: to unders'tand for these 

fields than for most other fields. Certain 

geologic features, howeve~,' ~ppe~r to have 

played a large part in the deterniination of the 

location of the pool and. of the position of the 

productive oil sand within ~he pool. _The following brief. description of .. the larger geologic 

features that control the accumulation of the 

oil along the west side of san: J<;>aquin valley is 

based upon a study ~hich extended over seyeral 

years of the geology of the Coast Ranges of 

Californi~. · Much of the material presented in 

this section has been published in an earlier 

report.1 The section describ'i:iJ.g the lesser 

_geologic. features that control the position of the 

productive oil sand within the pool is based 

largely upon the writer's _detailed study· of the 

Surtset-Midway field, chiefly the study of the 

data made available by the drilling.· . . 

LARGER GEOLOGIC FEATURES DETERMINING THE . '\-• 

. LOCATION OF THE OIL .FIELD. 

The main geologic features of the east. flf\.nks 

of the Temblor and Diablo ranges· are· fairly 

constant, for not only do both tariges lie ·on the 

edge of the great· structural trough occupied 

by. San. J oaquln Valley, but the ~~ockf?. :PaJi:mg 

up the two r·anges are of the samegen~ral c,haracter and.are'bent and folded in the same gen- · 

· etal way. The oil fields with:iri_ this ·region do 

hot, however, forni a 'co.ntinuolis b~lt fi.·om .one 

end of it ~o the pther_.but ~e.s~attered,-,t~·o,ugh 

it irregularly, the. po$ition they occupy_ being 

determined by certain definite ge0logic features. 

Just what the chief of these· features are it ·has 

been relatively easy to determine· 'by a comparison. of th~ ·productive. oil fiel4s. ~i~h the 

nonprod-qctive areas. ·1 ·., , • 

The . chief. geologic difference between; the 

areas along the west side.of San J~aqu~ Valley which contaib. commercial acc\.rinula'tions 

of oil and those in which' oil, .1f pr~seil~ at all, 

is disseminated through the rocks, .is that in or 

near the productive areas there are thick masses 

of diatomaceous shale and the rocks are bent 

into anticlines that serve as traps'in w~ch the. 

oil is held; .whereas the areas in which no·commercial pools occlp' do not contain both the 

shale and the structural trap, although they 

may con~ain either one or the other. 

1 Anderson, Robert, and Puck, R. W., U. S. Gcol. Survey Bull. 603, 

pp. 116-121, 1915. 

.· 
72 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

This general statement holds good for the 

whole west side of San Joaquin Valley, for no 

oil field has been developed within this area 

that does not contain both the shale in which 

the oil has originated and the structural trap 

in which it has been held. 

The importance of the obliquely trending 

anticline and of the deposits of diatomaceous 

shale a8 factors determinirig the position of 

commercial pools along the west side of San 

Joaquin Valley . has been discussed in some 

detail in an earlier report, 1 . from which the 

following quotation is taken: . 

The conclusion. appears unavoidable that the dominant 

factor influencing the accumulation of oil along the eastern 

flank of the Coast Ranges is the presence of the anticlinal 

folds in the formations bordering the San Jo~quin Valley 

and the corresponding synclines back of these anticlines. 

* * * In the whole region from the San E:m.igdio Mountains to Tesla not one of the well-developed f9lds that 

border the edge of the valley lacks evidences of the pres- . 

ence of oil either in or near it. On the other hand, there 

. is no evidence of oil at any point not in the general neighborhood of one of these folds. It is not meant to be implied 

that oil·occurs solely along the anticlines, for that is not 

true, but, as will be brought out below, oil invariably 

occurs either along such a fold or within an area believed 

to have been influenced by it. ~ examination of the 

province reveals the fact that in addition to seeps or evidence of oil obtained by wells along the anticlines that 

border the valley, similar indications occur almost invariably in the synclines and minor folds back of these anti-

. · clines at points along or in the foothills, whether the beds 

are or are not folded, at such interior points in a way that 

would ordinarily be considered favorable for the retention 

of oil. On the other hand, where there is no anticline near 

the edge of the valley no sign of oil appears either at the 

·edge of the hills or farther back, even though the character and attitude of the beds are practically identical with 

those of the oil-bearing beds at such interior points as are 

above mentioned. In other words; where an outlying 

anticline occurs the strata on the farther flank of the inlying 

syncline are oil bearing, even though they may be steeply 

tilted and truncated·; whereas tilted and truncated beds 

facing the valley. and 'not inclosed behind an outlying fold 

are barren. The conclusion is obvious that the anticlinal 

foldsexert:some kind of protecting influence on the strata 

· in the foothills to the west. * * * Farther south, along 

the eastern flank of the Tembl~r Range, there is a. fairly 

continuous series of oil-be::~.ring outlying folds. ·Back of 

these, along the flanks of the corresponding synclines that 

separate the anticlines from the foothills, the indications 

of oil.at the surface or in wells are numerous. * * * In 

this southern area the evidence of the protecting influence 

of the o~tlying folds is not quite so clear as it is farther 

north, owing to the. more complicated character of the 

folds and to the fa.ct that many of them are covered by 

Recent filling in the San Joaquin Valley. In general, 

however, the rule holds good that the outer folds are oil 

1 Anderson, Robert, and Pack, R. W., op. cit., P.P· 117-118. 

bearing and that they are followed on the west by a belt 

of :irregularly tilted strata likewiSe rich in oil. A good 

example is afforded by anticlines in the Buena Vista Hills 

and the highly productive synclihe of Midway Valley. 

1t is very doubtful whether the west flank of tha syncline 

would be so productive if it faced directly upon the San 

Joaquin Valley, without the intervening domes of the 

Elk and Buena Vista hills. 

The relation of these obliquely trending 

anticlines to the larger. structural featurethe great trough that is occupied by San Joaquiri Valley-must not be forgotten. It is 

believed tha·t in the central part of this trough. 

a great mass of diatomaceous shale exists, an.d 

that this shale. has furnished much· of the oil 

which is now concentrated in the folds along 

the west side of San Joaquin Valle:y. Indeed, 

it is this shale which lies beneath the younger 

Tertiary rocks in the central basin that must 

be regarded as the chief source of the petroleum, 

and- therefore those folds which lie along the 

border of the valley-chiefly those folds that 

trend out into the valley and, gradually sinking, plunge and are lost beneath the valley 

filling-have the most favorable structure for 

the accumulation of oil, for they are the traps 

located closest to the source of supply. Folds 

that lie in the higher parts of the range-such 

as those which occupy the center of the. Temblor R~nge west of the Sunset-Midway field 

(see Pl. II) or as those which lie in the central 

part of the Diablo Range west of Coalingahave no great feeding ground from which to 

draw their oil, and the beds along them are in 

consequence less likely to· contain great quan-

~ities of ·oil than the beds .along the folds on 

the border of the Great Valley. This fact 

can.. not be too strongly emphasized, for 

although the chief oil fields lie along the anticlines, it. is ·along those anticlines which are 

located about the periphery of this great 

structural trough that the really large fields. 

are found. A comparison of the location of 

the. producing fields along the west side of San 

Joaquin Valley with that of the anticlinal folds 

there, as indicated 'in figure 5 (p. 56), will show 

the force of this statement. 

The supposition that the oil now ·found 

along the edge of the valley originated in the 

shale in the central part of the . valley means 

that the oil must have migrated laterally for 

great distances, and in ~rder that this migration may have taken place either the avenue 

along which the oil has pa.ssed must have been 
~;· 

I 

C'C 

t-

~ p 

1'::1 

·H 0 

~ 

E-f 

1'::1 

Ill 

·, 

., 

o Well having initial output of 400 to rpoo bbls.daily 

• Well having il"!itial output of more than 00~ bbls.daily 

0 I Z ·3 4 5 MILES 

/~~~ 4~ 

~f 

v~ 

~ 

FIGURE 6.-Sket('h map of Sunset-Midway oil field showing position with relation to structure of wells having high initial output. 

~ + 

+ 

Axis of anticline 

Axis of syncline 
-~ 

74 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

so open that ~the p~ssage of the oil was easy or 

else the pressure .causing the oil to move must 

have been so great thateven though the path 

was difficult the oil' wa!3 forced to travel it for 

great distances. 

It has frequently been urged t.hat oil so 

heavy and so viscous as that commonly found 

in the California fields could never have moved 

into its present position through the finegrained sedimentary heels in which it occurs. 

Such migration, however, does not appear to 

the writer to be at all. unreasonable, for, (1.): as 

200 

.... 

Ui 

J: 

~150 0: 

J: 

<l: 

u.. 

!/) 

UJ 

UJ 

0: 

1.!) 

UJ ·o 

o ll!~tOO 

'~ 

\ 

,~'\ 

~ \ 

l~ 

,:\\ "' 

\\ 0-

1\' "'-" \ ·" 

\. 

TIME IN SECONDS 

20 30 40 

SCAt E FOR VIS ~OSITY OF WATER 

; ~ 

3 g (1) u> r': -· (1) r< 3 0 -o ..., ~- ~ £ Ol 

~ •, 

"""' (1) ., 

~ ........... 

--i--f-.-

0~ ....... 

~ r' t"-... 

""' ...... 

J r-.:::: ~ ;::::::::.::: 1::::... 0 

produced in the Sunset-Midway field has a 

fairly high temperature. None of it,, of course, 

has a temperature as high as 200° F., for only 

rarely are temperatures of more than 115° or 

120° recorded, but it is not· unreasonable to 

suppose that the temperature of the oil when 

it moved into the position it now occupies 

may have been somewha.t higher than it is at 

present, as it would have been were the oil 

sands buried somewhat more deeply than they 

are now. ·rt would thus seem that the objection raised that California oil is too viscous to 

.. 

l2.1o 8 cont · . atntng about 2% water 

-

15° E ~ 

0: 

~ ~- !'--... - ~ ~ r-:::: · contair ing about 2%water rt=== UJ 

a. 

~ 

w 

.... 

50 

0 

r-- ~~--- J. 

~ ~ -~ ~----r---- 16.lo 8 cont .J Jsoal~ r--

'&co in in ~ ~ S.co g about 2% water ~nta;,· ---..:.~ng about 2% water -

·' 

0 1,000 ~0 . 3,000 4,000 . 5,000 6,000 7,000 6,000 9,000 1_0,000 11,000 12,000 13,000 

-TIME IN SECONDS 

FIGURE 7.-Curvcs showing relation of" viscosity to temperature in several crude oils. 

is explained· in tlie section describing the migrate through the fine-grained -rocks is not 

features which determine the position of pro- particularly valid, ·for at fairly .high temperaductive oil sands within the fields, it is prob- tures it would move almost as readily as lightable that the oil has· changed in character gravity oil. 

since it first moved in'to the beds it now-occu- The, path along which the oil must have 

pies; (2) the viscosity of .petroleum varies tre- •moved to its present point of accumulation 

mendously '_Vith temperature, and moreover, has been a relatively open one, for the beds in 

as the variation is much greater for heavy oils which oil is found are fairly coarse grained. 

than for light (see curv'es in fig. 7) oils of differ- The most ope~ path along which oil could 

ent gravity and at norm.al temperatures of move has probably been through the beds that 

widely different viscosity tend at a tempera- lie at the base of the McKittrick group, close 

-ture of approximately 200° F. to become about to the unconformity which separates that 

· equally viscous. Much ofbthe oil which is now group from the underlying diatomaceous shale. 
PETROLEUM. 75 

This unconformity between the shales in whic~ position within the field and within the geologic 

the oil origina~ed and the overlying beds that section where the oil has collected in considernow conta!n the oil is al:inost as important a able quantity, the depth .below the surface of 

geologic feature as the attitude of the beds, so the productive sands, and the 'positi<;m of the 

far as the accumulation of oil is concerned. gusher sands, of the oil of light gravity and 

As to the exact :nature of the forces that have that of heavy gravity, and of water. A discaused the oil to move out of the shale, mi- cussion of these secondary features is therefore 

grate for great distances through the rocks, and of more immediate importance in the present 

accumulate in small anticlines along the border report, for, as they control the distribution of 

of the trough, little can ·be said.· Although the the oil within the field, a correct and scientific 

oil has concentrated along small anticlines, the development of the field must be based upon a 

conception-to which the term "anticlinal proper uri.derstanding of them. 

theory" is usually applied-that the sorting In the Sunset-Midway field these secondary 

is caused entii~ely by the difference in specific features may, for the purpose of discussion, be 

gravity between oil and water does not appear grouped into three main classes-(1) those 

to be at all reasonable. The hydraulic hy- · connected with the structure, (2) those conpothesis of accmnulation, which states that nected with the lithology of the beds, (3) those 

"n1oving water undar either hydraulic or capil- connected with ·the character of the oil and 

lary pressure has been the dii·ect agent of with the chemical reactions between the oil 

accU111ulation,'.' 1 seems more nearly to fit the and various substances in the water or in the 

observed facts in the fields along the west side rocks with which the oil comes into contact .. 

of San Joaquin Valley. This hypothesis does The effects of all these different features are so 

not, 'however, expl,ain adequately the causeS' intermingled that it is practically impossible 

for the hydraulic pressure of ttte n1oving water. to describe one without at the san1e time 

Recently an attempt has been made to de- n1aking considerable mention of nearly all the 

scribe the factors responsible for this hydraulic others, yet. th~ir importance may best be 

pressm·e, and under the designation "elias- understood by focusing attention :firs.t upon 

trophic theory" Marcel Daly 2 has· described a one and then upon another of the classes outpossible n1ode of .accmnulation of oil. Daly's lined above. . 

idea is essentially that the hydraulic pres- EFFEcTs· OF THE SMALLER STRUCTURAL FEATURES• 

sure which has caused the tnigration of the oil 

is developed chiefly by · the lateral pressure u~coNFORMITIEs. 

that caused the deformation. of the strata in The aid rendered by unconformities to the 

near-by regions. 'rhe forces of deforma~ion, Il).igration of. oil in affording an open highway 

he .believes, have tr.ansferred their effects :not · to the moving fluids has .already been spC?ken of 

only t.hrough the solid material that makes up in the discussion of the larger geologic featqres. 

the beds but through the fluids contaip.ed in the The effect of the unconformities is, however, 

pores in these beds. felt even after concentration has to a :very large 

. Ll~SSElt GEOLOGIC FEATURES CONTROLLING THE extent been· accomplished, .for their presence 

POSITION OF THE OIL WI).'HIN THE 'FIELD. gives the oil a fairly wide choice as to .the sand 

The factors briefly outlined in the preceding 

section were probably d01ninant in controlling 

the move1nent of oil over wide areas in San 

JoaqUin Valley, but these major factors have 

been to some extent rnodified and their effect 

perhaps increased, perhaps decreased, but 

certainly guided by an infinite nU111ber of lesser 

factors, which in the long run have been ahnost 

as in1portant, for they have ·determined the 

in which it will fi~ally lodge, and· in many 

places a choi<?e as to whether it will occupy· 

one, two, or more sands lying one above 

another. · 

T~ understand these relations one must appreciate the conditions under. which the beqs 

that now contain the oil were laid down. These 

beds-alternating .sands, clays, and gravelswere deposited in a body of water which at :first 

occupied only San Joaquin Valley but which 

1 M:unn, M. J., Tho anticlinal and hydraulic theories or oil and gas later, gradually enlarging and gradually deepenuccumulntlon: Econ. Geology, vol. G. P· 523• J!lO!l. ing, encroached upon and finally submerged the 

D])aly, M:arcol, 'rho diastrophic theory: Am. Inst. Min. Eng. Bull. 115, 

pp. 1137-11~57, 1916. · high land that stood on the site of the Temblor. 

0 .' 
\ 

76 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

Range. These.beds were laid down in a nearly 

horizontal position. . An individual bed, ending 

at the then existing shore line', really abutted 

against the land mass, and the series of horizontal beds lying one above another,. each 

upper one overlapping the . next lower and 

occupying a larger area, inay be compared to 

layers of sand ·contained in a huge bowl with 

gently sloping sides, the layers lying horizontal 

and abutting against the sides of the bowl. San 

Joaq~in Valley is the bowl, the Temblor Range 

is one side of the bowl, and the flat-lying beds 

'that gradually mount higher and higher until 

at last they submerge the range are the layers 

of sap.d that fill the bowl. 

The oil that has moved out of the diato~ 

m~ceous shale that underlies the central part 

of San. Joaquin Valley and collected ~long the 

plane of ·unconformity .tends to move upward 

along this plane,' or, in other words, along the 

inner surface of the bowl. This movement continues until the oil approaches -the surface-

.that is, until it approaches the outcrop of the 

oil-bearing bed. Near this point the oil, as a 

. result of natural fractionation or of reactions 

·with minerals contained in the ·water or in the 

rocks, becomes heavy or tarry and very effectually clogs the pores of the -rocks. When 

this happens the free movement of the oil 

upward ·along the p~ane of unconformity is 

retarded and finally stopped. The forces that 

caused the oil to move out from the center of 

the valley continue active, however, and the 

oil, blocked from outlet at the surface, seeks 

an outlet through one' of the more sandy and 

n:to:r:_e porous beds that. abut u.gainst the plane 

of unconformity. As all the beds that overlie 

the diatomaceous shale abut against the unconformity at one place or another, the oil has 

a great number of beds from which to choose 

in picking a porous bed. Through this porous 

bed the oil moves outward, and in many places 

downward away from the plane of unconformity. 

The distance that the oil moves away f.rom 

the unconformity is probably not more than 

a mile or so and usually mttch less than that, 

·for the sands that have so far been penetrated 

by the drill show a diminishing quantity of oil 

with increase in the distance from the plane of 

unconformity, and, moreover, they fray out 

into a number of small thin sands. . But the 

real end of the movement of oil in this direction 

seems to be reached when tl_te oil, owing to an 

D 

encounter with mineral waters or with some 

mineral in the rocks, changes to a tarry product 

that clogs the pores and so seals up this high-. 

way, just as the outcrop was sealed up against 

further movement toward the surface. When 

this point is reached the oil, which is still being 

forced upward along the plane of unconformity, 

must seek another avenue of escape along some 

oth~r porous bed. 

The final result of all this is th~ impregnation 

with oil (1) of a sand or a group of sands along 

the plane of unconformity and (2) of a number 

of other sands that start at the plane of unconformity and extend out from it. When 

viewed in cross section this arrangement of the 

oil sands looks like a .great branch from which 

minor pranches or twigs extend· ~ut in one 

direction only, the sands along the plan<;) of 

unconformity being the main branch ~nd the 

sands that extend out parallel to the bedding 

of the strata being the twigs. Or perhaps the 

whole arrange~ent may better be compared to 

a great flight of stairs. · 

The position of the different oil sands that· 

extend out from the plane of unconformity is 

very irregular, for the oil follows the more 

porous beda, and the lithology is extremely 

variable. In one part of the field there may 

be only a single thick sand, in another part one 

or ·two thin sands in addition to the thick sand, 

and in still another part two or three thin sands 

which are sharply distinct from one another. 

Within a distance of several hundred feet from 

the plane· of unconformity the oil, so far as can 

be determined from the drill r~cords, is not 

restricted to fa!rly well defined sands but is 

scattered more or less. through the entire section. This lack of definition in the ip.dividual 

oil sands close to the unconformity is proba'bly 

due very largely to the fact that in that vicinity · 

all the beds are more .or less coarse and irregularly grained. At.least there is no such sharp 

difference between impervious clay and evengrained sand as there is in the beds farther 

removed from the unconformity. As all the 

beds in the area close to the unconformity 

have much the same degree of porosity, all 

are more or less equally filled with oil. 

The arrangement of the oil sands described 

above will be better understood by reference to 

the diagrammatic section given in figures 8 and 

13, or to the ·n1ap that shows the conditions in 

Maricopa Flat (Pl. XLIII). The mode of occurrence of oil in this field can not be understood 
PETROLEUM. 77 

until it is· realized that the oil-bearing sands 

do not lie as a great unbroken blanket beneath 

the surface and do not as a rule even lie parallel 

with the bedding but that they form a zone 

which as a whole is parallel to the plane of 

unconformity that marks the top of the diatoInaceous shale. 

A feature of great practical importance in the 

development of the field is the fact that the 

different 'sands that extend out from the plane 

of uncon.fornrity overlap. In any partiql.;J.lar 

area there are therefore a shallow sand and a 

deep sand, or perhaps even several deep sands 

lying at different depths below the shallow 

sand. As all the oil sands that extend out from 

the u.nconfor1nity are in1pregnated with oil 

for about the same distance, and as the plane 

of unconfornrity dips eastward, the uppermost 

sand is the fiTst one to· become barren toward 

the east. 'fhe sand does not, of course, become 

barren abruptly, n~r even at a uniform distance 

fron1 the plane of unconformity. The content 

of oil gradually di1ninishes, and the line marking 

the eastern limit of the,area in which the wells 

derive their oil from a particular sand is very 

irregular. This irregularity is due in part to 

the natUTal irregularity in the oil content of the 

sand and in part to the difference in the attention paid to the sand by the different operators. 

Some of the operators, considering that even a 

sn1all atnount of oil in the sand is worthy of 

attention, attempt to recover it, whereas other 

operators drill through this sand without paying the least attention to it and get their oil from 

some deeper sand. It is this zone in which 

a sand becomes lean or barren and in which the 

handling of the wells is so diverse that the 

writer has called the "transition" zone or belt. 

The handling of the wells in such a zone is of 

great iinportance, for unless a uniform method 

is adopted, water is certain to be let into the 

sands that contain oil and to ruin more or less 

cmnpletely the rich oil sands that Jie a consid-

' m·able distance away. 

Sl~CONDAH.Y AN'l'ICLINES AND SYNCLINES. 

Although the anticlines that extend out 

from the 1nain range are of very great importance in the concentration of the oil inasmuch 

as they mark tl~e points at which the oil tends 

finally to lodge, the secondary anticlines that 

make up most of these obliquely trending folds 

appear to have exerted very little individual 

influence on the ·concentration of the oil. 

It might be supposed that these small folds, as 

for example the small sharp anticlines on the 

south flank of the Elk Hills or the individual 

anticlines in the .central part of the Buena 

Vista I-Iills, would be the most favorable 

points in tho whole region for oil to collect. 

'But the beds beneath the small folds in the 

Elk Hills are barren, and those that lie directly 

beneath the axes of the small anticlines in .the 

Buena Vista Hills appear to be. no richer in 

oil than those that. lie beneath the axes of the 

small synclines in the same part of the hills. · 

The failure of these anticlines to affect the 

concentration of the oil is to be explained by 

the fact that they are really no more than 

surface wrinkles and do not as a rule appear 

as individual flexures in the oil sands. In considerihg the oil prospects of the outlying hills~ 

therefore, it is necessary to deal with the folded 

belt or zone and not with the individual folds 

'that make up this zone, the structUTally 

highest part of the zone being regarded as 

the most favorable for the concentration of 

oil, and the anticlines that lie low on the 

flanks of the· upward-folded. zone being regarded as unfavorable, even though these folds · 

are sharp and distinct at the Slil'face. The 

difference between the structure of the surface 

beds and that of the beds that lie several hundred feet beneath the surlace is well shown in 

Plates II and III. The f~;tilure to appreciate 

the fact that these folds are shallow has led to 

the drilling of a very considerable number of 

wells along the axes of sharp anticlines that 

stand almost ·at the edge of the folded zonesuch folds, for example, as the small ones on 

the south slope of the Elk Hills. Such locations, although not entirely hopeless, can not 

by any means be said to be attractive, for it is 

the center of the whole ap.ticlinal belt, which 

in the case cited embraces the whole of the Elk 

Hills, that is the most promising part. 

The lack of importance attaching to the 

individual anticlines in the anticlinal zone or 

belt that embraces the Buena Vista Hills is excellently shown by the wells on the MeN ee lease 

of the Standard Oil Co., in sec. 36, T. 31 S., R. 

23 E. On this lease are several of the largest 

wells in the whole Sunset-Midway field. The 

lease, which covers a square nrile, lies almost in 

the center of the anticlinal· belt of the Buena 

Vista Hills and is crossed by several small anticlines and synclines. It so happens that several of the largest wells are located along the 
78 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

axes of t~e synclines, not along the anticlines; 

and, conversely, several of the smallest wells on 

the whole lease are precisely on the axes of th~ 

small anticlines. The. contour map (Pl. III) 

shows how greatly the small folds are flattened ~t the horizon of the oil sands, and thus 

why it is that they have had so little in.dividual 

. effect on the concentration o.f the oil. 

In the section describing the effect of the unconformities (pp. 75-77) the stairlike arrangement of the oil sands in the western part of the 

field is discussed and the fact is pointed out 

that the oil has entered the sands it now occupiAs by mo~ing chiefly :first through the. porqus 

sands that lie along the plane of unconformity 

and then eastward parallel to the bedding 

through sands that abut against that ,plane. 

The entire movement of the oil has not, however, occurred in this .manner, but in·places as, 

for example, along the anticlinal belts of the. 

Bu.ena Vista and Elk hills the oil has quite evidently been able to move vertically upward 

through the strata. Along these belts the oil 

is now found in a number of sands through a 

stratigraphic thickness of 600 feet or more. 

Many of the sands that contain oil along these 

antjclinal. l;>.elts do not contain oil in the syn-

<?lina~ basin that separates the belts from the 

main range. on the west, and it appears· very 

improbable that the oil could have woved east-. 

ward from the plane of unconformity clear 

acros~ t~e intervening syncline to fi:nd a resting 

place ~ the higher parts of. the outlying. an,ticline wit~out leaving some considerable trace 

in theb~ds in the syncline. There is. also other 

eyideuce, such as the presence of the shallow tar 

zone in the vicinity of. sec. 25, T. 31 S.', R. 22 E., 

which shows that the hycfrocarbons are. able to 

move vertically through the strata. This evidence is discussed on page 88. It is important here to note that the vertic'al movement is 

most marked ~nd perhaps is of practical impor-· 

tance only in the belts where the beds are folded 

strongly upward; The relation of the oil sands 

in the outlying anticlinal belts of the Buena 

Vista and Elk hills to those along ·the edge of 

the main Temblor Range is shown in the cross 

section in figure. 8. . . -

EFFECTS OF. LITHOLOGY. 

The litho logy of the beds which overlie the 

diatomaceous shale and which now contain the 

oil in the Sunset-Midway field is, for several 

.. 
PETROLEUM. 79 

reasons, i~nportant in a consideration. of the 

occurrence of oil. · The porosity of the beds 

1nust be great enough to permit them .to absorb 

a very considerable quantity of fluid; the open 

spaces in the rock-that is, the "voids"-must 

be of sufficient size to permit these fluids to 

n1ove fairly freely through the rock; and 

finally the porosity of the different beds must 

be different, for otherwise there would be no 

particular tendency for the oil to concentrate 

in certain beds, but rather would it tend ·to 

dissetninate through all the beds. · 

In the Sunset-Midway field the lithology of 

the beds overlying the shale is diverse to the 

extrenle, the beds ranging from coarse conglonlerate through aln1ost every. conceivable 

m.ixtm·e of grain to the finest, most compact, 

and n~ost hnpervious clay shale. This variation is not only vertical fr01n bed to bed but 

nlso horizontal within a given bed. These beds, 

therefore, contain many adn1irable reservoirs 

in which the oil may oollect, for many of the 

porous lenses are almost completely surrounde~ 

by the n1ost ilnpervious clay. The very lenticularity o~ the beds is, however, somewhat o~ 

a detrilnent, for the productive oil sands are 

not continuous, and the field is in consequence 

s01newhat ''spotted." The practically barren 

belt along the northeastern slope of Twenty-five 

I-Iill is an exan1ple of the control that the 

lithology exercises over the concentration of 

petroleun1, for, as is explained in the detailed 

description of this area, th~ lack of oil here is 

due to the fact that there are in this ar.ea no 

suitable porous sands in whic~ the oil might 

collect, . and the oil has ther~fore collected in 

the irmnediately aqjacent J.l,reas, where such 

sands are plentiful. 

It n1ay not be out of place here. to point out 

that the porosity of a bed is, theoretically, in 

ho way dependent qn the size of the grain but 

rather upon the shape of the individual grains, 

the arrangmnent of the grains, and their regularity in size. Theoretically the porosity of a 

bed cotnposed of spherical grains all of one 

dimneter is equal to that of ~ny· other bed 

con1posed nlso of spherical grains of son1e 

uniform size, provided only that the grains are· 

arranged in a sin1ilar manner in. the tw·o beds. 

It 1natterl? not at all whether the grains of one 

bed are large and those of the other stuall-a 

foot in di~1neter in one and a fraction of an 

inch in the other-if the grains are arranged in 

a similar manner in the two beds, and if the 

grains of one bed are all of one size and thos~ 

of the other bed all of the other size, then the 

porosity of the two peds is the same. 

The shape. of the individual grains exerts a 

great influence over the porosity of the bed, 

for if the grains are of such shape that they 

may be fitted tightly together-as, for example, 

is the ·case with particles having large flat 

sides-the porosity may be .very greatly decreased. Uniformity in the size of the grains 

is equally. important, for if the bed contains 

a mi.."'{ture of large and small grains the small 

ones will fit into the "voids" between the 

larger grains and thus reduce the porosity. 

The size of the grain in incoherent sands 

such as those that are fotind in the SunsetMidway field does n<;>t necessarily indicate the 

porosity of the bed, but it .is a fair measure of 

the size of the "voids," for although beds that 

contain coarse fragments may have the size 

of the "voids" decreased by the addition of 

smaller fragments, the "voids" would hardly 

be la~ger than the grains if the bed is reasonably 

compacted. Therefore, other things being 

equal, the coarser-grained beds are the 'ones 

that offer the .more attractive reservoirs in 

which the oil, particularly viscous oil, may 

collect. Porosity and coarseness of grain 

should not be regarded as synonymous terms, 

however, for they are not. Many very fine 

grained . sands are much more porous . tha.rl, 

coarse-grained sands near by, and these fine 

sands offer by far the more attractive reservoir 

for light oils. . · . · 

. The reade:r; interested in the factors that 

control the porosity of mixtures of sand will 

find excellent dis9.uss!ons of them in the 

writings of King 1 and Slichter.2 

In the course of his work the writer had .the 

opportunity to study the lithology not only 

of the outcrops of the 'oil-bearing beds but also 

of the oil sands penetrated. by the producing 

wells, more than 400 samples from different 

parts of the field being obtained. This study 

showed ·c~early the following facts: (1) The 

beds close to the unconformity that marks the 

top of the diatomaceous shale are usually 

1 King, F. H., Principles and conditions of the movements of ground 

water: U. S. Geol. Survey Nineteenth Ann. Rept, pt. 2, pp. 59-294, 

1899 • 

. s Sliehter, C. S., Theoretical investigation of the motion of ground 

waters: Idem,.pp. 295-384. Sec also U.S. Geol: Survey Water-Supply 

Papers 67, 110, 140, 141, 153, 184. 
80 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

coarser grained than those that lie at a little porosity of that sand, but to .understand why 

distance from the shale, and not only do these the finer sand is the more porous it is necessary 

beds contain coarser fragments but they are to consider once more the conditions that 

more . uniformly coarse grained·. (2) At. a governed the deposition of these beds. 

little distan,ce from the Unconformity the oil The beds that now contain the oil are 

sands are not the beds that contain the coarser composed of detritus brought down into the 

fragments but rather the fine-grained beds that San Joaquin Valley from high land that lay 

are composed of fairly well rounded grains of where the Temblor Range and the San Emigdio 

uniform size. (3) In many parts of the field Mountains now stand. In all probability 

the oil sands are :r;emarkably fine grained, many niost of .the debris can1e from the west-that is, 

of the sands having more than 80 per cent of from the area now occupied by the Temblor. 

their grains smaller than 200 mesh. ·Range. The hills that made up this area of 

' The fact that the beds lying close to the high land were composed of diatomaceous shale 

unconformity are coarser grained than those in which there were some beds of sand and 

that lie at a little distance from. it is quite· coarse boulders, consisting almost wholly of 

what is to be expected, for these beds were laid fragments of granitic rocks. In other words, 

down close to the hills from which the detritus the range was then. composed, much as it is 

was derived, and, as is usual, the coarse frag- t<;>-day, of diatomaceous shale With lenses of 

ments were deposited near the edge pf the coarse material. The coarse beds· were so 

basin of deposition while the smaller and lenticular that quite naturally the detritus 

lighter ones were carried farther out toward the derived from the hills varied from place to 

center of .the basin. Clays that are very com- place, here being almost entirely fragments 

pact and in consequence very impervio'us occur of shale, here entirely fragments of granitic 

near the unconformity, but they are not so rocks, and here a mixture of the.two. Morecommon there as in the center of the valley. over, the character of the material brought 

All the beds near the unconformity are there- into the l;>asin at a given spot varied from time 

fore fairly coarse and also fairly porous, and to time, for as a lens of conglomerate became 

any oil that works its way into these beds worn away the detritus obtained changed from 

. finds them all about equally attractive as fragments of granite to fragments of shale. 

reservoirs and so impregnates them all about There is thus a very great variation in the 

equally. Thus there is formed in the beds lithology of the beds, both vertically and 

that lie immediately above the plane of uncon- horizontally. 

formity a thick succession of oil sands. More- The coarse debris that was derived from the. 

·over, these beds, being fairly porous and also lenticular masses in the diatomaceous shale 

fairly coarse grained, are able to contain fairly was so heavy that most of it was dropped fairly 

thick and viscous. oil such as that which· is close to the edge of the basin of deposition and 

found in the western part of the· field close to thus forms part of the succession of coarse 

the outcrop of the oil sands. The character bed~ near the, unconformity at the top of the 

of the oil in this part of the field is of course due shale, but the finer particles were carried 

chiefly to the relation the sand bears .to the farther out and now form the fine-grained sands 

surface and to surface waters, but it· is very that are found in the cent:ral part of the 

probable that if these beds were not coarse valley. On the other hand, the diatomaceous 

grained the oil would not be so heavy as it is, shale in weathering tends to break up into 

or at any rate that the thickness of the beds needle-like splinters, into flattish particles of 

that contain the heavy oil would be very much fair size, and into a fine dust or mud. The 

less. larger fragments of shale are on the whole of 

The fineness of the oil sands that lie at a considerably greater size then the rounded 

little· distance from· the plane of unconformity ·grains of granitic material that were carried 

is very striking, but even more striking is the out into the valley, but nevertheless because 

fac~ that these sands are in many places under- of their light specific gravity the shale particles 

lain or overlain by beds ~hat contain very much· were carried well out into the valley. It is 

coarser grains than the oil-bearing sand itsel.f. very common, therefore, to find that the beds 

The selection of the finer-grained sand by the in the central part of the valley that contain 

oil is of course due to the relatively greater the coarser fragments are composed of a very 
PETROLEUM. ·81 

c01npact clay shale-the dust or mud derived 

fr01n the diat01naceous shale-in which there 

are set a greater or less nmnber of flattish 

s~1ale fragments of fair size. It is evident that 

a bed c01nposed of such detritus fr01n the 

diat01naceous shale can not be as porous as a 

bed con1posed of well-rounded particles of 

approxhnately the smne size, and. thus it is 

that the fine granitic sands in the central part 

of the valley are the beds that now contain the 

oil even though they are in places exceedingly 

.fme grained. 

The control that lithology exercises over the 

porosity of the bed and therefore over the 

distribution of the oil is excellently shown in 

the vicinity of the northeast corner of sec. 25, 

T. 31 S., R. 22 E., a short distance north of 

Fellows. This area has proved to be one of the 

1nost spotted in the whole field~ for here wells 

that flowed at the rate of many thousand 

barrels daily are situated among wells that 

produce so little oil that it hardly pays to 

pun1p then1. Moreover, the large and the 

small w~lls obtain oil from the same sands. 

An exatnination of satnples of the oil sand from 

the wells in this area showed quite clearly that 

the variation in the productiveness of the wells 

was due to the variation in the lithology of 

the beds, 'for without exception in the samples 

at the writer's disposal the sands from the 

flowing wells were made of well-rounded grains 

of granitic n1aterial-small grains, perhaps, 

but free fron1 clay or detritus from the diatotnaceous shale-whereas the sands fro.n1 the 

wells that produced only a little. oil were all 

· very. "muddy." The most productive saud 

in this area was of very fine grain but also of 

re1narkably even grain, and, as the grains were 

about equally light and dark, it looked much 

like a mixture of finely ground pepper and salt. 

In considering the possibilities of undeveloped portions of the field a great deal of 

attention ha.; frequently been given to the 

size of the grains making up the bed, and certain 

areas, as, for example, the E~k Hills, have been 

c01idemued, for it was believed by many geologists that the sands there were too fine grained 

to permit them to act as reservoirs. It is retnarkable, however, just how fine grained some 

of the producing oil sands really are, and the 

writer believes that no portion of the whole 

Sunset-Midway field lacks beds porous enough 

to make. satisfactory reservoirs for the oil: 

109288°--19---6 

Small areas, as, for exam1~le, the northeastern 

slope of Twenty-five Hill, lack porous beds, or 

at·leust the beds in these areas are much less 

porous than those in the immediately adjacent 

areas, but no large area seems to be without 

adequately porous beds. A large proportion 

of the oil sands that the writer examined were 

very fine grained, 50 to 80 per cent of many of 

the samples passing through a 100-mesh screen 

and some of the samples containin~ an equally 

large amount of material that passed through 

a 200-mesh screen. In these sands there· was 

very little indeed that would not pass through a 

60-mesh . screen. These sands are in reality 

little more than the finest sort of dust, yet it is 

just suoh fine dust that seems to contain the oil 

in the parts of the field where the producing oil 

sands do not lie· immediately adjacent to the 

unconformity that maTks the top of the diatomaceous shale. 

The writer believes that in this region any 

isolated anticline in which theoformations above 

the diatomaceous shales are present is to be 

regarded as a po.ssible reservoir of oil, provided, 

of course, that the beds in which the oil would 

normally occur-that is, those closely overly-· 

ing the diatomaceous shale-are within reach 

of the drill. By an isolated anticline is meant 

one that is separated from other s-tructurally 

high areas by structurally low areas, or synclines~ 

·Those who have condemne.d parts of the 

field because of the lack of coarse-grained . 

sands forget that (1) coarseness of grain is not 

necessarily an indication of porosity, but that 

fine-grained beds may be very porous; (2) the 

thick tarry oil found in the western part of the 

Sunset-Midway field is not char.acteris.tic of the 

field as a whole, and the normal oil is fairiy 

fluid and can readily occupy v~ry small pore 

spaces; (3) it is vastly more important, so far 

as the concentration of 9il is concerned, to have ' 

beds of different porosity than to have coarsegrained bed.;, for unless there is a distinct 

difference in the porosity there can be no concentration of the oil in certain beds and thus no 

formation of commercially valu~ble ''pools." 

An especially instructive example of the 

character of the oil sands was seen in the hills 

west of the producing :field at Maricopa. Here 

there is exposed in the sides of a deep gulch an 

oil sand that forms part of the zone from wh_ich 

the wells in the field to the east obtain their. oil. 
82 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

This sand, which is ·1 or 2 feet thiok, is underlain by a conglomerate composed of fragments 

of diatomac~ous shale ·embedded in a sticky 

·clay that is· also composed of detritus derived 

from the shale. This conglomerate, de3pite its 

· ooarse grain, is practically impervious and contains no trace of oil. The oil san<;! is overlain 

by a grit in which th,e grains are on the average 

· 2 or 3 millimeters in diameter, b11t the grit, too, 

. is practically. impervious, for it is tightly 

cemented, nearly all the pore sp'ace being filled 

with ·a calcareous cement-, and it also contains 

no trace of oil. The oil sand itself is exceedingly fine grained, more .than 90 per cent passing a 200-mesh screen and all of it passing an 

80-mesh. One could hardly imagine a finergrained sand, yet this sand is filleg with oil. 

Upon the lithology of the bed depends to 

some extent the . character . ·as well as the 

quantity of the oil, for the gravity of the oil 

varies with the grain ·of the bed in which it 

occurs, the lightest oil being found in the finegraineq beds and the heaviest· in the coarse 

conglomerates. As described in Part II of this 

,· ·.report the character of the oil depends largely 

upon its ·distance below the surface or from 

mineralized water; yet the:r:e is a very distinct 

d:Mference between the oils in the shaly beds 

and those in the coarser sands, where 'other 

fine grained, a large proportion of the particles 

composing them being small. enough to pass 

through a 200-mesh screen. The beds yielding 

thev ''shale oil'' are still finer grained. Very 

frequently the shales when first drilled into 

yield a large amount of oil daily, and, moreover, the oil is under a very heavy pressure. 

Usually, however, the pressure decreases 

rapidly, and soon the well must be pumped or 

perhaps refuses to yield more than a :r;nere 

dribble of oil. The rapid decline in.the production of the wells that obtain oil in such fi11e 

shaly beds means of course that the oil can 

not move through the fine beds freely enough 

to permit the rate of production to be maintained, but the original pressure is of interest, 

for this pressUre is· apparently more or less 

localized and seem.s to have b~en built up from 

within the pool, not from without. In another 

section of this report the writer has advanced 

the idea'that the pressll!e is caused by reaction 

within the pool after the oil hasbeen more or 

less comp~etely sealed up by the tarry oil 

formed about the edg·e of the pool as a result 

of other reactions, and it is of interest here to 

note that the pressure is more localized. and 

~xceptionally high in the finer-grained beds, for 

these beds are more readily ·sealed up by such 

tarrifica tiou· of the oil. 

conditions are apparently the same. This EFFECT OF THE CHEMICAL AND PHYSICAL CHARACTER 

. difference, however 7 is natural, for the. thick . OF THE OIL. 

tarry oil~ are too viscous to move freely through Besides such physical fitctors as the lithology, 

the finer sands. ~or is it likely that the position, and attitude of the beds containing 

character of all the oil in. a pool would be the oil, there are other facto~ that exercise. a 

changed by the reaction with mineral waters, control over the ?oncentratwn of the otl. 

for such reaction would probably result in the Among the· most ImJ?ortant of these other 

alteration of the oil only along the very outer. fact~rs are. t~e c~emlC~ character .and ~he 

edge of the pool, _beoause to ~change the .oil relati~e chenncal ~nsta~ihty of the oil, ~vhich 

thr. h t th · 1 th · ld f "t cause It to react With mineral substances In the 

oug ou e poo ere wou o necessi y · h · ali d. · d · 

b "d bl t f th h. strata or In t e miner ze water containe 111 

e some conai era e movemen o e eavy h f · h · d 

il-th ' uit. of th eaction-thro h th t e strata to orm varwus e~vy compoun s 0 e res e r · u~ e that serve to seal the outcrops and to make 

fine pore. space. M~r~over, as there IS less closed pockets in which the unaltered and. 

opportunity forth? 01l to move freely t~rough lighter oil may collect and remain. 

the· very. fine g:amed bed~, so there IS less The factors causing the alteration of the 

~pportun1t~ for It to fractiOnate and for the oil are outlined on page 87 and are dishghter.p?rtiOns t~ l~ave.. . . . cussed somewhat fully by Mr. Rogers in 

. The difference m the. ch~racter of the o~ Part II of this report (Professional Paper 

In the coarser sands and In the very fine clays IS 117). The mechanical effects upon the conreadily recognizable, and the term ''shale oil'' centratioii of the oil of this chemical change 

is in common use among the ~perators to in the oil are discussed in the section dealing 

describe the oil obtained from the clays or ·with the importance of the unconformities as 

shales. These beds are truly clays or.shales, agertciesaidingconcentration(pp. 75-77). The 

for, as is shown in the preceding pages, many subject is merely mentioned here, simply to 

of the most productive sands are exceedingly. emphasize the fact that the chemical character 
PETROLEUM. 83 

of the oil has quite as great an influence in 

·controlling concentration as the physical features of the beds in which the oil is contained. 

It is therefore not necessary to do more here 

than to point out the fact that were it not for 

this tendency of the oil to oxidize readily 

and so to clog the outcropping beds and thus 

p.reYent the remainder of the oil from escaping, 

there would probably now be very little if any 

oil in the part of the Sunset-Midway field 

lying west of the axis of. the Midway syncline, 

but all the ·oil that had not escaped at the 

surface would probably be that 'vhich is contained in such structural traps as the anticlines 

in the Buena Vista· and Elk hills, where the oil 

sands are completely buried. 

In other fields, where the oil is not of . an 

asphalt but of a paraffin base, and where no 

such heaYy tar is formed either at the surface 

or at depth close to mineralized waters, the 

concentration of the oil is goYe:r;ned more completely by the lithology, the attitude, and the 

position of the strata, and it is only in the 

upper parts of tl;te an:ticlines or in the porous 

lenses in the strata that the oil is concentrated 

and retained. In relatiYely steeply tilted outcropping beds such as those along the west 

side of the Midway syncline light, mobile oils 

that do not oxic;lize readily would soon escape 

at the surface, leaving almost no evidence that 

they had 'formerly been present in the beds in 

considerable amount. 

· 'rhe influence of the character of the hydrocru.·bons upon the concentration and retention 

of the oil is shown also in the relatiYe position 

of the oil and gas. Throughout the field the 

dry gas lies above the oil, and in the Buena 

Vista I-Iills the beds containing the dry gas 

are distinct from and lie several hundred feet 

above those containing the oil. The position 

of this dry gas so far above the oil is due, of 

course, to the greater mobility of the gas and 

to 'the ability it possesses to move in a general 

vertical direction through the strata that are 

impervious to the thicker oil. But besides 

. this dry gas, there is a very considerable 

quantity of wet gas in the same strata with the 

oil. This wet gas is contained in a given 

stratum more or less throughout a large area, 

but it is most abundant in the higher piu·ts of 

the anticlines. All the small folds in the 

Buena Vista I-Iills are more or less undulatory, 

·and it is in the uppei· parts of these folds--or 

ono might say in the domes-that most of the 

gas is contained, whereas the stratum that 

contains gas in the domes contains oil where 

it is downfolded in the saddles of the anticlines. · . 

The most striking example that the writer 

has noted of this segregation of oil and gas ill 

the same· stratum; according to its position 

with relation to the structure, is that shown in 

the south-central part of the Buena Vista Hills, 

for the oil sands that compose the upper part . 

of the oil zone in the MeN ee lease, in sec. 36; 

T.31 S., R. 23 E., contain gas in the area farther 

south, and it is from these sands that many·of 

the deeper gas wells of the Honolulu Consolidated Oil Co. der~ved their gas in 1916. 

The segregation of the oil and gas within the 

same stratum is evidently due in part to the 

greater mobility o.f the gas but chiefly to the 

difference in specific gravity of the two fluids. 

The result is therefore in a way an example of 

concentration according to the anticlinal theory 

by which oil, gas, and water are presumed to 

concentrate in the anticlinal folds and to arrange themselves in more or less definite layers 

according to their specific gravities, the lightest 

fluid (gas) above, the heaviest (water) below, 

and the fluid of intermediate gravity (oil) in. 

the middle. 

Although in the example cited the oil and 

gas are evidently arranged more or less according to their specific gravities, the writer 

believes that the arrangement is not a primary 

one, but only a secondary readjustment after 

the fluids as a whole have collected along the 

axis of the anticline. In other words, the 

difference in the gravity of the two hydrocarbons or of the hydrocarbons and water has 

not been the factor ' that caused the hydrocarbons to accumulate and to remain where 

they are now found, but once they had col-: 

lected there, the difference in their specific 

gravities caused a readjustment whereby the· 

different fluids came finally to occupy more or 

less definite layers. 

PRESSURE UNDER WHICH OIL EXISTS IN THE 

POOLS. 

In practically every part of the field the oil 

is under. a pressure considerably greater than 

atmospheric pressure, and in consequence many 

or perhaps most of .the wells flow when first 

brought in. The pressure varies greatly, but 

in many of the wells it was, during the early 

life of the wells, 1,000 pounds to the square 
84 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I.. 

inch (66 atmospheres) or more, and in one migrate, o~more correctly to the pressure devel~ 

well it has been reported as 2,000 pounds to the oped by the forces causing migration-seems 

squt;tre inch (133 atmospheres). As a whole to the writer to be entirely unjustified. To 

the pressure, particularly in the Buena Vista assume that it is true onlj makes the interpre1-Iills~ was considerably greater than hydro- tation of other.phenomcna connected with the 

static pressure-that is: it was greater than the oil more difficult. 

pressure exerted by a column of water equal For example, why is it, if the pressure is the 

in height to the distance. the particular sand resistance built up to the forces that caused the 

was buried beneath the surface. migration of the oil, that ·the oil is not forced 

The cause of this pressure has been the sub- back over the path it 01ice traveled as soon as 

ject of a great deal of speculation, and many the forces that caused the original migration are 

ideas have ·been advanced to explain it, for any no longer active~, How-is it that the oil remains 

theory that really seeks to expla"in the mode of concentrated ·and still under this pressure 

accumulation of oil in the earth must'explain, di- which caused it to concentrate-a pressure the 

rectly or indirectly~ the pressure under which writer is tempted to call "fossil pressure," as 

the oil is now found. Practically all the theo-· it is so clearly a relic of the past and of an earlier 

ries of oil accumulation explain this pressure as and very different condition of things. 

the result of the forces that have caused the con- In other fields-as, for example, those of 

centration of the oil, regarding it as the resist- northern Louisiana-whe;re the pressure in the 

ance built up in the pool at the time of concen- oil sands bears a ~ore o~ less constant relation 

tration to the forces that were causing the oil to the depth that the oilsands lie beneath the 

to collect, and, as the oil is now at rest, regard- su#ace; the pressure may reasonably b~ termed· · 

ing this resistance as being able to 'offset these hydrostatic, for it is roughly the same as that 

forces and therefore equal in amount and acting ·of a column· of water that is equal in height to 

in the opposite direction to them. . I the depth that the oil sand is buried. But in 

For example, the anticlinal theory, which parts of the Sunset-Midway field, where no such 

relies upon the difference in the specific gravity relation exists and,the pressure in the oil sands 

between the hydrocarbons and water to supply is characteristically greater "than hydrostatic, 

t~e force that causes the petroleum to move some other explanation must be looked for. 

and to collect, explains the pressure now exist- To the writer it appears evident that (1) the 

ing in the pool as purely and simply hydrostatic pressure under which the oil is now held is very 

pressure. The hyd!~aulic theory dodges the largely independent of the forces that caused the 

question and explains only the segregation of original concentration of the oil; (2) the presoil and water and gas, given the initial condi- sure was probably built up very largely within 

tion of moving fluids .. The diastrophic theory the pool after the oil had been collected. 

recently advanced by Marcel Daly1 definitely ·A possible and to the writer the most probable 

states that the pressure now existing in the pool . explanation of the way in which the pressure 

has been built.up in resistance to the forces that under which the oil is held was built up is that 

caused the initial movement and collection of the oil, after having been collected in a certain 

the oil; these forces being the same that have area in a more or less definite pool, is held 

caused earth movements or diastrophism in under~ pressure which may be very moderate 

some area in the vicinity, though not necessarily indeed and which has been built up in oppoimmediately adjacent to the area in w~ch the sition to the forces that caused the oil to 

oil has collected. · migrate originally and to collect where it has. 

The central idea about which all these After the concentration has been effected, the 

"theories" are grouped....:_that the pressure now oil reacts more or less with the mineral subexisting in the oil fields is intimately related to stances with which it· comes into contactthe forces that have caused the concentration of those making up the rocks or those in the 

the oil,· or, as some of the more de:E.nite andposi- water. The extent to which such reactions 

tive of the "theories" state~ is quantitatively take place and the nature of the products 

equal to the pressure that caused the fluids to formed is at present very largely a matter of 

· ' conjecture, for very little is known as to the 

t Daly, M:. R., The diastrophic theory, a contribution to the study of exact chemical make-up of .the petroleum as · the mechanics of oil and gas accumulation in. commercial deposits: Am. 

Inst. Min. Eng. Bull. 115, pp. 1137-1157, July, 1916. it exists ln the ground, of tlie exact chemical 
' ' 

•. , 0 ,. 

i :. 

PETROLEUM. 85 

~hangcs that it undergoes, or of the products 

formed by such changes. There is, however, 

abundant evidence that one of the products of 

· the reaction between the petroleum and the 

mineral subs.tances in the waters that occur in 

the Sunset-:Midway field is a thick, heavy oil or 

tar. Now it so happens that in nearly every 

oil pool the oil is normally in contact with 

water at the edges of the pool, for usually 

water occurs in the oil sand down the dip 

from the area in which the oil occurs. At the 

point where the oil and the water are in con-. 

tact, therefore, a tar plug is formed that stops 

up the porous reservoir sand, preventing. the 

further encroachment of the water and incidentnlly preventing the oil from moving out of 

the reservoir. After this plug has been formed 

tho oil is held in a tight reservoir bounded 

above and below by the impervious beds that 

overlie and underlie the porous sai:id and on 

tho sides by the tarry plug that fills the pores 

of tl1o sand. 

Once the tight reservoir has been formed 

nny reaction that results in the formation of 

light or gaseous hydrocarbons will cause an 

increase in the pressure under which the oil is 

held, for the pressure can not be relieved by a 

simple pressing back of the oil and water over 

the path that they have traveled in effecting 

tho original concentration. .As to the possible 

reactions that might cause the formation of 

gaseous hydrocarbons the writer can offer no 

suggestion, but he is convinced that such reactions are not at all improbable, and when one 

considers the unstable nature of the hydrocarbons that compose the petroleums and the 

case with which just such changes can be 

effected in the laboratory, they seem qui.te to 

be expected. 

T4ere is no question that a thick tar is 

characteristically formed where oil and mineralized waters of certain 'types are in contact. 

This has been shown time. and again to be true 

by wells drilled in pretty nearly every part of 

the field. Invariably where tar has been 

found at depth it has been found either in beds 

that immediately overlie water-bearing, beds 

or, if in the main oil sand, at the outer edge 

of the pool and wells drilled still farther out 

have encountered only water in the sand. As 

the tar or tarry oil is remarkably viscous it is 

. equally evident that only a small quantity of it 

would be necessary to seal a porous sand completel:y:- and make of tb..at sand a very perfect 

-and tightly closed reservoir .. Just what changes 

take place in the oil that is inclosed in the 

reservoir is a problem that . is well worth 

detailed study-a study tpat must involve a. 

great deal of careful chemical work. At 

present far too little is known as to the true 

nature of the oil or of the possi blc reactions 

that might take phrce to venture any definite 

statements, for very little work has been done 

on the chemistry of .petroleun:;t that will throw 

light on the subject. 

As has been pointed out above, there is no 

definite relation between the pressure and the 

depth that the snnd lies beneath the surface. 

The pressure is greater iri the parts of the 

field where the sands lie deeper, it is true, but 

the increase in the pressure is not proportionate 

to. the increase in depth. Rather it appears 

that the pressure bears some sort of relation to 

structure, for it is far greater in the Buena 

Vista Hills, where the beds are strongly upfolded, than in the central part of the ~1idway 

Valley, where the oil sands are even more 

deeply buried than they are in the Buena 

Vista :Hills but .where they are downfolded 

in to a syncline. 1 

It is quite apparent that variation in the' 

hydrostatic pressure can not have been the' 

cause of this variation in the pressure in the 

oil sand in the two areas of opposite structure, 

nor is it reasonable to tliink that if the pressure in the oil sands. is a reflection of the 

pressure that caused the accumulation of 

the oil, the pressure would vary so greatly in 

areas so close together. The· writer believes 

that this variation is due to the fact that along 

the anticlines there is greater opportunity for 

the forn1ation of more. perfectly sealed reservoirs than there is along the synclines, for, 

as will be seen from an inspection of :figure 

13 (p. 115), on accoun~ of the unconformity 

betw:een the diatomaceous shale and the 

overlying sands, the· oil has opportunity to 

work its way into a very considerable number 

of sands before it is finally sealed completely 

in all of them. This movement of the oil is· 

explained more completely in the section that 

deals with the effect of the unconformity on 

the accumulation of the oil {pp. 75-77) .. The 

oil is pre.tty thoroughiy sealed in by the formation of tar in the oil sand on both flanks of · 

the anticlines, and the oil is thus prevented 

from working its way into other beds when 

the pressure in the original reservoir becomes 

fairly great. · 
-86 THE SUNSET-MIDWAY OIL FIELD~ CALIF.-PART I. 

. EXPLANATION .OF THE "GUSHER SANDS." of the oif from sands in the Buena Vista Hills 

The theory has been advanced that the and. other parts of the field where the oil sands 

reason for· the exceptional richness of the oil lie deep is 21° to 28° Baume (0.9271 to 0.8860 

sand hi certain spots in the field. ·is that at specific gravity). · 

these spots the oil sand in the moderately . As to the chemical character of the oil very 

tilted beds of the . McKittrick group rests little can be said other than that it is asphaltic, 

directly upon the ·truncated edge of an oil for the published work on the true nature of the 

Sand in the steeply 'tilted. diatomaceous shale oil· is. very meager indeed. Almost the only 

formation .. · The well therefore supposedly work the results of which have been published 

has a much greater· reservoir from which to that has been done in determining the exact 

draw and in consequence yields much more oil. nature of the hydrocarbons. that compose the 

. This theory has been a very popular one, oil.is that o£ Peckham and Mabery, and their 

but it appears to the writer to be entirely work was done with so few and so scattered 

untenable, for (1) it necessitates the. suppo- samples that it will hardly serve as a basis for 

sition that peculiar and really very unusual any very definite conclusions. p Moreover, none 

conditions exist in innumerable places in the of the samples that they examined came from 

field; (2) in n1a:ny places the large "gushers" the sands in the deeper parts of the Sunsetare not so deep as the neighboring wells and Midway field, where the oil is probably much 

get their oil either fr9m "stray" sands that lie more nearly in what might be termed its origiabove the main productive zone found in nal state than it is in the sands near the outsurrounding wells or in the very uppermost crop-that . is, in the sands from which the 

part of the zone. A few of the large wells samples that were analyzed came. · The results· 

that derive their oil from relatively shallow of analyses and other chemical studies of the 

sands are Associated (Pioneer Midway) well oils of the region are reviewed by Mr. Rogers 

No. 2, in sec. 30, T. 31 S., R. 23 E.; Kern in Part II of this report (Professional Paper 

Trading & Oil well .39, in sec. 1~ T. 32 S., 117). 

R. 23 E.; American ·Oil:fields well 79, in sec. It is hopeless to expect that any great per36, T. 31 S., R. 22 E.; and Honolulu (Hawaiian) manent advance will be made. in the study of 

welllO, in se·c. 31,.T. 31 S., R. 23 E. All the such problems as the origin of the oil, its alterabig flowing wells. in ~ec. 32, T. 31 S., R. 23 E., tion, or even its accumulation until some serious 

got their oil from beds that lie above the. and systematic study of the chemical nature 

.deep sand encountered i~ Alaska Pioneer well of the oil is made. The ordinary "analyses" 

9 and G. P. well 6 (Fellows 32), and even the that show the fractional distillation of a sample 

'two last..:named wells· derived their oil from ·of oil, ·the viscosity, the gravity, and perhaps 

beds in the lower part of the McKittrick. the amount of sulphur and of unsaturated hy-

. 'It seems much more probable that the true drocarbons are of o~y a ve:ry little use to the 

explanation for these exceptionally rich partS geologist in his study of these problems. What 

of the s~;tn.4 'is either that where they occur is needed is the determination of the exact nathe sealing up of the reservoir has ·been more ture of the hy~rocarbons that compose the oil 

complete, or ·that the formation of tlie light in a number of specially selected samples taken 

hydrocarbons. in the'· petroleum trapped in at different parts of some such field as the 

the . reservoj.r. has b~en more extensive; or Sunset-Midway field.· Samples that are typical 

perhaps b<;>th factors have been operative. as nearly as possible of the original oil, of oils 

This .. explanation is in a measure supported that have. been altered by interaction with 

by the fact. that a large number of the .big various mineral substances, and of others that 

flowing wells yield oil of slightly lighter gravity are altered owing. to oxidation should. be anathan the wells immediately surrounding them. lyzed before we can do more than speculate in 

CHARACT~R OF· THE OIL: l· 

The oil ranges in. gravity from less than.ll 0 

to,32° Baume (0.9929 to.0.8641 specific gravity). 

The average gravity of the oils frqm sands near 

the outcrop· is betw.ei:m. 14.? '.and 18o. Baume 

(0.9722 and 0.9459 specific gravity);" and _that 

.a most general way as .to the general nature of 

the oil, of the way in which ·it is collected, or of 

the changes that it undergoes. 

· But until such info.rmation·is available it may 

not.be out· of' place to point.out one· or two. 

things regarding the variation of -the gravity of 

the-o.il, for the gravity•·varies considerably and 
PETROLEUM. 87 

seems to bear some relation to the structure, to 

the presence of w.ater,, and to the depth of the 

oil sand beneath the surface. 

Along the west side of the field-in the Spellacy anticline (Twenty-five I-Iill); in the field 

about the town of Maricopa, and along· the 

foothills of the main range as far as the north 

end of the field-the oil is fairly heavy, thick, 

and tarry. Its character here is probably due 

· to the oxidation of the oil upori. its close approach to the s1.uface, or to the action of surface 

waters. 

In the parts of the field where the oil-bearing 

· beds lie deeper the main oil sand is in places 

underlain by tar, which by its proximity to 

water-bearing sands indicates clearly that the 

reaction of the oil and the water have been the 

cause of the formation of the tar. 

Also in the Buena Vista Hills the lightest oil 

in a given sand is apparently that which occurs 

in the highest structural position. The reason 

for this difference is probably to be fouri.d in the 

fact that lighter and more mobile' hydrocarbons 

have moved to the highest parts of the folds. 

Finally, there is a decided difference in the 

gravity .of the oil in the coarse-grained sands 

and· that in the very fine and compact shales. 

A large number of distillation ·tests and 

determinations of gravity and other physical 

features of the oils from the Sunset-Midway 

field have been recorded in bulletins published 

by the Bureal! of Mines.1 H~wever, all the 

available chemical and physjcal information 

will be found in Part II of this report, where 

it is summarized and discussed by Mr. Rogers. 

EFFECT OF MINERALIZED WATERS ON THE OIL. 

In 1910 Mr. E. A. Starke, ·then chief chemist 

for the Standard Oil Co. of California, called 

the writer's attention to the fact that the 

surface waters of the California oil fields appeared to react fairly readily with the oil. 

These surface waters are primarily sulphate 

waters, and by the reaction with the hydrocarbons they are reduced, giving rise to free 

sulphur or to hydrogen sulphide. At the 

san1e time the hydrocarbons are oxidized, 

giving rise to carbonates. Just what reac~ 

tions take place ca.J;l. npt be told, for .. tP,e. e~act 

nature of the hydrocarbons that make ~p· the 

1 Allen, I. C., and Jacobs, W. A., Physical o.n:d cheptical properties.of 

tho petroleum of tho San Joaquin Valley, Calif., with a chapter on analysis of nat!Jral gas from tho southern California oil fields, by G. A. Burroll: Bur .. Mines Bull. 19, 1911. Allen, I. C., Jacobs, W. A., Crossfield, 

A. S., and Ml,\tthows, R. R., Physical and chemical properties of the 

petroleums of California: Bur. Minos Tech. Paper 74, 1914. 

oil is not known, but the general type of reaction is expressed by the subjoined formula, 

although as methane is a fairly permanent ga.s 

this reaction itself may never take place to an 

appreciable extent: · 

CaS04 + CH4 = CaCOa + H2S + H20 . 

The carbonates formed by reactions of this 

type remain dissolve·d .in the water, and the 

·waters close to the oil are thus changed from 

sulphate to carbonate. But the sulphur or . 

the sulphides unite more or less with the oil to 

form thick and tarry products. 

The discovery of the tendency of the oil to 

-react in this manner was turned to advantage 

in a v'ery practical m~nner by :Mr. Starke., for 

he held that. as the tendency for this reaction 

was evident and pronounced, sulphate-bearing waters could not exist in the vicinity of 

oil and that in. the oil zone, therefore, only 

carbonate waters would be found. In· drilling "wildcat" wells . a careful . examination 

was made by his company of the water encountered in the various water sands, and as 

long as they showed .abundant sulphates .. it 

was considered that oil did not exist in the 

vicinity; but as soon as the sulphates disappeared and· carbonates appeared great care was 

taken to examine all the sands. penetrated· to 

determine the presence or absence of oil or 

gas. Remarkable ,success was had with this 

procedure so long as mire was taken to obtain 

samples of water really typical of that contained in the bed penetrated. · The method is 

of course adaptable only. to' those :r;egions 

where the surface ·waters are filled with sulphates, as they are in the California fields. 

Some years later G. S. Rogers, 2 of the United 

States Geological Survey, while investigating 

the chemical relation of the' oil and water in 

the California fields, elaborated this theory· 

and built upon· it· a classification of the 'waters · 

encountered in these fields. · · 

In the previous sections of the present 

report the writer ·has · p6inted ou£· that the · 

reservoirs containing the oil are sealed· up by 

tarry oil or tar which is:·formed by the interaction of the rp.ineralize'd waters and the hydrocarbons ·that compose the ·oil:· It ·is a reaction · · 

of the type· described above__.;_ the reduction of 

sulphate· •water ·to -form ·sulphides ;and the 

addition of'the·sulphur or sulphides rto'the oil'-

2 Rogers, G. s., Chemical ~elati~~s of the oil-field waters in San Joa-' . 

quin Valley, Calif. (preliininary report): u: S. Geol. Survey 13ull. 653, ·. 

119 pp., 1917. . 
88 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

that the writer belie.ves is responsible for the tar are not filled with oil· to the weJt but lie 

formation of. this tarry plug.· above the productive zone there as well. To 

In general these reactions that result in the the writer this tar is explicable only as markingformation .of tarry products may he divided the dept4 to which the surface waters extend. 

into two classes, or perhaps more properly the At this depth they encountered hydrocarbons 

zones in which reactions of this type .take of some type, probably gaseous, .that were makplace may be divided into two parts-that ing their way more or less vertically upward. 

close to the surface and that at greater depth, One can hardly believe that natural fractionin many places at the very base of the oil ation of the oil has caused the formation of the 

zone, below the beds.contahiing the productive tar at this particular depth, for why if the tar 

oil sands. · is the result of a gradual fractionation should 

The reactions that take place close to the not the underlying beds between· this tar zone 

surface, particularly along the outcrop· of the and the productive C zone contain tar also ~ 

oil-bearing beds, result in sealing up the out- Were the tar the result of natural fractionation 

crop and preventing the escape of the oil at there should be a gradation fron1 the oil sand 

the surface. The extent to which the oil below to the tar sarid above, in the amount 

:undergoes alteration is evidently far greater and character of the oil or tar c~ntained. 

near the surface than it is at depth, for the The effect of the' deeper waters on the oll is 

deposits ·of tar and of sulphur are greater not so extensive as that of the surface waters, 

there. This. is tQ be expected, for the surface but it is evident none the less, for in place 

. water characteristically contains more sulphates after place where water is found in the oil 

than the waters at greater depth, and more- ·sand a deposit of tar or heavy· oil separates 

over the oxidation of the oil is aided to a large the portion of the sand occupied by oil from 

extent by other oxidized products in tb.e rocks that occupied by water. The reason for the 

that lie close to the surface, or by exposure to lesser effect of the deeper waters and thus for 

the air itself. Not only are. the oils at or the smaller amounts of "tar in the deeper sands 

near the surface changed more or less com- is evidently the fact that the waters 'in. the 

pletely to tar, but the sulphate waters are deeper sands contain normally a far smaller 

changed so completely that _great .quantities of amount of sulphate than the surface waters. 

free sulphur are. form-ed, and deposits of native According to the views of the writer the deeper 

sulphur such as the one .occurring south of waters are not by any means to be considered 

Old Sunset result.. Sulphur is widely scattered as truly connate waters-that is, the waters iri 

along the foothills in which the oil sands which the sediments composing the beds were 

crop out, but such extensive deposits of sulphur laid down, still retaining the same chemical 

as those near Old Sunset are found only character as they had at the time of deposition. 

locally, where they have accumulated for. some For it is evidently quite unreasonable to believe· 

reason. The cause of the sulphur deposit at that these waters have remained quietly in 

· Old Sunset appears to be ~he concentration of the beds, retaining unchanged their original 

oil and sulphate water ~dong a fault zone. character, while other fluids, such as the 

An interesting bit of evidence as to the petroleum, have entered the beds and filled 

depth to which the oxidizing effect of th,e sur- completely the pore spaces in some of them.· 

face water·extends is shown in the wells north DETAILS OF THE PRODUCTIVE FIELD. 1 

of Fellows, near the east line of sec. 25, T~ 31 

S., R. 22 E. Here the wells encounter a DOHENY PACIFIC-CARNEGIE AREA. 

persistent .tar zone. between 800 and 1,000 

feet below the surface. This zone appears to 

lie more o.r less parallel to the surface and not 

to correspond exactly to the structure, although 

·. the dip is so low. here that it is difficult to be 

certain that the tar bed is not exactly parallel 

to the bedding. In the beds some 600 or 800 

feet thick below the tar zone and above the top 

of the produ.ctive C zone no other notable oil or 

tar sand occurs. The sands that contain the 

[Southwestern part of sec. 1; sees. 2, 3; eastern part of 

sec. 4; northeastern part of sec. 9; sees. 10, 11, 12; 

northern p~rt of sec. 13, T. 31 S., R. 22 E.] 

LOCATION AND OPERATORS. 

· The Doheny Pacific-Carnegie area lies north 

of the main part of the North Midway field 

that is now productive and south of the MeI These detailed descriptions of parts of the productive field and the 

conclusions expressed are based on data made available by the drilling 

done up to July, 1916. · · 
DOHENY PACIFIC-CARNEGIE AREA. · 89 

Kittrick field. In 1916 it contained but few 

productive· wells:· In the extreme southeastern part, in sec. 12, are the producing wells of 

the ·:Midland Oilfields Co. and General Petroleum Co. (Oakburn) ; and in the extreme 

northern part, in sec.' 3, are those of the Doheny Pn.ci:fic Petroleum Co. In sec. 34, just 

north of the Doheny well, are the old and now 

· nbandoned wells of the Associated and :Mamn1oth companies. 

the Belgian anticline in the preliminary report 

on the McKittriek-Slmset region 1 and is shown 

on. the map accompanying that report as making an abrupt double bend in the middle of 

sec. 34, T. 30 S., R. 22 E., adjoining the Sham-. 

rock anticline. There is, however, no direct 

evidence that. the two anticlines join in this 

manner, but rather they appear to be separate 

folds that overlap like the folds in the Buena 

Vista and Elk hills. The Belgian anticline is 

GEOLOGY. short, probably not continuing southeastward 

The geology here is complicated, resembling much beyond the point in sec. 2 where it disthat of the :McKittrick field, which lies just to appears ·beneath the allt1vium. The beds close 

the north, and this area n1ay be considered as to the axis are fle~ed rather sharply, however, 

the extreme south end of the region controlled and at its north end diatomaceous shale in the 

by the structure appearing in the ~1cKittrici\: ·upper p~rt of the :Maricopa shale is brought to 

field. The chief structural features here, from the surface. 

southwest to northeast, are (1) the fault along The'syncline lying between the Belgian antithe eastern edge of the Telephone Hills; (2) cline and ·the Rudisill anticline is likewise 

the North Midway syncline; (3) the Belgian short, plw1ging eastward abruptly.' The Rudianticline, in sec. 2; (4) the small syncline sill anticline is a well-marked fold, and the beds 

crossing the north line of sec. 2; and (5) the near its axis .. are tilted steeply. The. fold 

Rudisill anticline. plunges s.outheastward but probably not so 

~1ovement along the fault in the Telephone abruptly as the ·North Midway syncline. The 

I-Iills has been considerable near the north line structure in tlus regio.n is shown on th~ geologic 

ofT. 31 S., R. 22 E., where beds of the McKit- section (Pl. XVI). 

OIL SANDS. 

trick group on the east have been dropped and 

abut against the diaton1aceous shale and gravel 

in the upper part of the· Maricopa· shale. The In the western part of the area here dedisplacement along this fa\)}t gradually lessens scribed-that is, the part forming the west 

towurd the southeast, and in sec. 15 the fault limb of the North Midway syncline-the sand 

merges with the Globe anticline. In the Tele- which ofieFS most promise of yielding oil is 

phone I-Iills, in the extreme western part of the comparable to the B sand of sec .. 15, T. 31 S., 

area here discussed, the beds are consid~rably R. 22 E., just to the south, and of the area along 

fractured on both sides of the fault, and the the foothills ·still farther south in the same 

line shown on the map marks only the center of township. Little can be said regarding the 

this z011·e of fracture. On account of the large position 'and character of the oil sands here, as 

am01.u1t of fracturing and the meagerness of the· only a few wells have penetrated them. The 

dat~ furnished by the surface exposures and wells drilled west of the axis of the North Mid .. 

by the few wells drilled h~re it is impossible to way syncline that have penetrated the sand 

contour the oil zones in this area. which is· productive in sec. 15 have .found it 

The North Midway syncline is a shallow fold either dry or filled with tar or with water. 

that plunges rather abruptly .toward the east Most of these wells have been drilled into the 

and is almost if not entirely lost near the east Maricopa shale, which immediately underlies 

line of sec. 13. · On the east flank of the fold the sand from which oil is to be expected, and 

the beds are highly tilted, in places to angles of have found oily shale, streaks of oil sand, and 

40° or 50° .. The irregularity in tilting is evi- water sand. The Carnegie water we~l obtains 

dently due to the presence here of small faults water 2 from a deep sand in the Maricopa shale, · 

similar to those so abundant in the west flank at least 3,000 feet and probably 3,400 feet beof the~ same syncline-that is, along the east low the base of the McKittrick group. This 

edge of the Telephone I-Iills. sand is said to contain some oil, the estimate 

The anticline that trends sol!theastward and being made that 5 t~ 10 barrels is brought up 

crosses the north line ofT. 31 S., R. 22 E., just 

west of the northwest corner of sec. 2 is· termed 

• 

1 U. S. Gcol. Survey Bull. 406, p. 136, 1910. 

2 Soo analysis in Table 24, Part II (Prof. Paper 117) • 
90 THE SUNSET-MIDWAY OIL FIELD, CALIF.-'PART I.. 

daily with th.e water. In all, ··~bout eight wells line of sees. 14 and 15 will probably prove nonhave been drilled in this western part of the productive. The oil sands he~e are badly frac-

·area, and they have shown that, although the tured, abundant opportunity has been given 

beds in the lower part of the McKittrick contain for the oil to escape, and the sands are probably 

some oil, the amount is small and it is doubtful occupied chiefly by tar and water. Moreover, 

whether enough oil will be found, except in on accolint of the presenc~e of numerous faults, 

small isolated areas, to_make drilling profitable. it is difficult to predict the· exact position at 

The absence of oil here is probably to be ex- which the sands will be encountered. Oil will 

plained by the facts that there· is in this area no probably be found in commercial amount in 

dominant structural feature along which oil some parts of the area, but the oil sands are 

would tend to collect, and that between this unquestionably disc.ontinuous, and search for 

area and the Great Valley are numerous anti- them will be expensive. 

clines that would act as· traps to intercept any In the central part of the syncline in sec. 3, 

oil moving westward from -the shale lying be- the southwestern part of sec .. 10, and the northneath the valley. western part of sec. 11 the sands will probably 

The oil-saturated sands which rest upon the not :yield a great quantity of ~il, as they appear 

. diatomaceous shale that is exposed along the here also to be fractured. However, the cover 

crest of the Belgian anticline near the center of in this area is greater and the opportunity for 

the north lme of the.NE.! sec. 3 are at the base the escape of the oil less, and doubtless wells 

of the McKittrick and correspond to the B zone. drilled here would yield a small quantity of oil. 

These sands.may be pr0ductive along the axi~l Farther down. the plunge of the synclinepart of the Belgian anticline to~ point. at least that is,. in the southeastern part of sec. 11, the 

as far southeastward as the center of sec. 2, northern part of sec. 13, and the southern part 

where the anticline disappears beneath the of sec. 12-the product~ve sands are in the 0 

· alluvium. , zone, the. B zone being occupied by .water or 

The B zone, however, will probably not be tar. In this area wells similar to Midland Oilproductive for more than a short distance down -fields No. 1 and General Petroleum (Oakburn) 

the flanks of the Belgian anticline; for the dips No. ·1 can probably be obtained, but the sand 

are fairly steep, and in ·other parts of the field here is probably not. so pr.oductive as it is 

where the beds are highly tilted-notably along farther south, closer to the crest of the Globe 

the foothills southwest of Fellows-the belt anticline. In this area it will be necessary to 

beneath which any particUlar zone is 9il bearing case off the B sand, which contains water, and 

· is narrow. Therefore on either the east or the also to avoid drilling into the bottom water, 

west flank of the Belgian anticline beyond a which probably is only slightly below the 0 

narrow belt that occupies the crest· of the fold zone. The 0 zone here is probably not Jnore 

oil should be looked for in beds correspondirig than 100 feet thick. 

to the C zone, for if oil occurs there at· all it is · So far little prospecting has been done along 

prohably in this zone. Sands in the 0 .zone the axial part of the Belgian anticline. The 

have yielded the oil obtained in the Midland· only well that had been drilled here at the 

Oilfields wells 1, 2, and 3, and· the General Pe- date of writing {August, 1916), is the gas well 

troleum Co. (Oakburn) well 1. of the Section 3 Oil Co., which encountered a 

In the southeastern part of the area here de.:. flow of gas estimated at 18,000,000 cubic .feet. 

scribed the C zone is about ioo feet thick and The gas is evidently derived from sandy measis underlain by a water sand, just as it is in the ures in the diatomaceous shale in . the upper 

southeastern part ofT. 3l S., -R. 22 E. In this ·part of the Maricopa shale not far from the 

part of the area the B zone contains water, the base of the overlying McKittrick group. The 

water sand apparently corresponding- to the Belgian anticline plunges southe·astward, and· 

water sand encountered ll(~ar· the southwest because of the abundant evidence of the prescorn:er ·of sec. 13 and lying about 100 feet above ence of oil afforded by the seep· in the canyon 

the top of the C zone. · that crosses the north line of sec. 3 about a 

.. quarter of a mile west of the northeast corner 

SUGGESTIONS FOR ini~VRE DEVELOPMENT. · of the section, the gas encotintere~ in the well, 

Much of the area lymg west of the axis of the and .the· gas blowout in the· NE. l sec. 2, the 

· North Midway syncline and n~rth of tbe north southeast ·end of this anticline offers one of the 

• 
ENGINEERS-COALINGA MONTEREY AREA. 91 

Iliost pr01nising parts of the North Midway 

field for future drilling. Wells here will probably 

not be "phen01nenal gushers," but practically 

all the southwestern part of sec. 2 and much of 

_the sm·rounding area offers promise of yielding 

a fair quantity of oil. 

ENGINEERS-COALINGA MONTEREY AREA. 

[SW. t and southwest~rn part of NW. t sec. l3, E. ! sec. 

14, NE. t sec. 23, and NW. t sec. 24, T. 31 S., R. 

22 K] 

LOCAG.'ION AND OPERATORS. 

Oakland Midway properties. The 0 ' zone 

along the east line of the NE. i sec. 23 is described as gravel and coarse sand and is filled 

with fossils. · The ·pebbles making up the 

gravel beds are said to be well rounded, black 

(probably quartzite), and. from a quarter to 

half an inch in size, and the sand grains to 

average between an eighth and a quarter of an 

inch in .. diameter. I:ri one well log the upper o 

part of the 0 zone is reported as an indurated 

gray sand, but in all others it is recorded as 

loose sand~ ) . . ']~he Engineers-Coalin0

0'a Monterey area lies · The upper sands in the western part of the 

in the northeastern part of the North Midway · are.a are m the Etchegoin or possibly in part in 

field and ernbraces the land lying on the north- the Paso Robles formation. The lower or c 

ern flank of the east end of the Globe anticline. zone is certainly in the Etchegoin, as is shown 

(See geologic section~, Pls. XVI and XVII.) by the abundant fossils it contains along the 

.'1.11e c01npanies operating here in 1916 were east line of the NE. i sec. 23. The 0 zone is 

the Doheny Pacific, Oakland Midway, Qenetal probably the basal part of the Etchegoin, 

Petrolemn (Dabney, Bear Creek), Engineers, although, as only a very few wells have been 

Onisbo, Stockton Midway, K.ern Tradmg & Oil, drilled through the water sand that underlies 

Pacific Midway, and <;Joalinga Monterey. . the productive d zone, its position can not be 

GEOLOGY. stated with certainty. The distance between 

· Tlus area l~es at the crest ~nd on the north the top of the B zone and the top of the C zone 

flank of the Globe anticline and extends as far InCreases greatly eastward, ranging from about 

northward as the axis of the North Midway 200 feet near the north-south center .lines of 

syncline. The Globe anticline is here·a broadly sees. 14 and 23 to about 500. feet near the east 

. rounded fold, which plunges abruptly east- lines of ·those sections. . 

ward, and a short distance east of the center In its western part this area includes a por- . 

of sec. 24 the arching effect is almost com- · tion of the so-called transition belt, where oil 

pletely lost. This anticline is essentially the occurs in the lower sands (the 0 zone) and also 

western continuation of the Uillted anticline ·in small quantities iri. beds that in the area still 

in tl{e north end of the Buena Vista Hills but farther .west are productive-that is, in the B 

the two folds are separated in sec. 19, T. a1 S., zone, ·which yields oil in sec. 15 and the W. ! 

R. 23 E., by a saddle that forms the north end sec. 14. In the eastern part of this area, howof the Midw~y Valley syncline. This synclin~ e.ver, these upper sa~ds.conta~ only t.ar an~ a 

may be reO'arded as separatinO' the structural httle water, the mam productiOn commg from 

features whlch form part of the0 Temblor Range the lo'~~r or ~ ~on~. - . fron1 those which form the outlying Buena The transitiOn belt extends roughly along 

Vista and Elk hills, the Globe anticline belonO'- the north-south center lines of sees. 14 and 23 

ing to tho 1nain range and the United anticl~e to. the vicinit;r of the ·mi'ddle of ·sec. 23. In 

to the outlying foothills. Both the North this belt some wells are perforated for the 

Midway syncline, on the north side of the Globe upper sand, but· in many the upper. sands are 

anticliJ.?.e.' and· the Twenty-six sp;tcline, on the c~ed ,~ff with the w~ter strTI:tg· : In the "tran- . 

south side, plunge steeply eastward. .The ~Itlon. bel~ the maXImun: thickness of the zone 

steep plunge is shown on the map (Pl. III) by m w~ch ~il sands occur IS about ·500 feet, and 

tho underground contours, which bend only of. this thickness the lower 100 .to 200 feet eonvery slightly for any one of the three ·folds. stltutes the 0 zone. . The 0 zone varies in thickness, the maximum 

OIL. SANDS. 

In sec. 13 the oll sands are very fine grained, 

be4tg virtuaijy sandy shales. ' SaiJ..d ·of this 

character i~ fo~<;l in t:P.e Doheny Pacific and 

being about 200 feet~ · In this ·measurement 

are included both the oil ·sands. and the intercalated barren beds, fpr the ·productive sands 

themselves are in-few places more than ~.oo feet 
92 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

thic.k. Usually n:ot over 50 feet of oil sand is 

recorded or provided for in perforating the 

casmg. 

BEDS ABOVE THE B ZONE. 

Above the B zone occurs the usual mixture 

of day, grav~l, shell, and shale. There is nothing very notable in the character of these beds 

unless it is that they are somewhat coarser 

~ grained than most of the other beds along the 

western margin of the productive field. 

. Tar sands are fairly abundant up 'to a level 

within 200 or 300 feet of the surface and are 

thickest along the ~xis of the Globe anticline, 

in the NE. i sec. 23 and the NW. i sec. 24. 

Near the center of the west line· of sec. 13 a 

tar zone about 100 to 200 feet thick lies 600 

to 800 feet above the top of the B zone. 

Neither above this tar zone nor below it for a 

distance of 400 feet is much tar sand recorded. 

This thin tar zone has beeri recognized also in 

some of the wells along the south line of sec. 13. 

In the western part of, this area, however, 

the B zone is really the bottom part of a thick 

tar zone, tar sands continuing above it for, 250 

to 300 feet. Water is abundant in this tar 

s·and near the center of the west' line of sec. 13. 

WATER SANDS. 

Bottom., water.-The·c zone is underlain by a 

very persistent saline water sand which up to 

the middle of 1916 had been penetrated by 

about 15 wells in this area: There is very 

little record of the flow of water from this 

sand, but it is reported that in one well a 

3-inch pump running at full capacity could 

not exhaust the flow. 

rrhis water sand is very persistent, closely 

underlying the c zone is much of sees. 23 and 

24 and almost all the water trouble in this 

part of the field has come from drilling into it. 

Near the center of the north line of· sec. 23 

the water is so near to .the C zone that it· can 

. only with great difficulty be shut off properly 

once it has been entered, and several of the 

wells in this general locality have let and are 

· possibly now letting water from this sand 

into the oil sands of the C._zone. · 

O~y one well in this area has been drilled 

through this water sand into the underlying 

strata. In this well. numerous other water 

sands were encountered .in a distance of more 

than 500 feet below the water that lies just 

below the C zone. 

Top and edge water.-ln the we.stern part 

of sec. 13 water sand occurs with the tar sands 

that either .form the uppermost part of the B 

zone or immediately overlie that zone. This 

water is recorded in the l,ogs of several of. the. 

wells in the southwestern part of sec. 13, the 

southe~tern part of sec. 14, and the northeastern part of sec. 23 and is the same as that 

which was. designated the "lower top water" 

in the W. ! sec. 14. It is so close 'to the top 

of the B zone (if it is not actually in that zone) 

as to be practically edge water for the upper 

part of the B zone. This water has been somewhat troubleso~e in the "transition" belt. 

Another ·and still more troublesome water 

sand is found· below the top of the B zone and 

above the top of the C zone. It is recorded in 

th~ logs of. several· wells near the southwest 

corner of sec. 13. This water · has been 

cemented off from the c zone in . all these wells 

but is quite free to enter the upper or B zone. 

It becomes more and more pro~i;nen t toward 

the southeast, on the south flank of the Globe 

anticline, and is 'recorded in the logs of several 

of the wells in theSE. i sec. 23. The approximate position of this water sanCl is shown in 

the geologic seq tion (Pl. XVI). 

PROPUCTION. 

For the most part this area contains no wells 

that had a very high initial production. One 

well is said to have had an initial production 

of 1,000 barrels daily and to have produced an 

average of 650 barrels daily for the first month. 

A few other wells, about five in all, made at 

first_ 200 to 500 barrels a day. · 

The rate of decrease here is rather high. 

One group of five wells is said to have lost 25 

per cent of its "settled" production in one 

year. Another group of 15 or 16 wells is said 

to have lost two-thirds of its "settled" production in one year. 

In 1914 the daily production of individu~l 

wells in this· area ranged from 10. tb 150 

barrels, and the average daily production o'f 

wells near the west. line of sec. 13 was about 

60 barrels .. In the southeastern part of the 

area here discussed the wells averaged about 25 

barrels daily. · 

CHARACTER O,F THE OIL. 

The gravity of the average oil in the C zone 

is about 20° or 21° Baume, but the oil obtained 

in the wells ranges from about 16° to 21° 
U. S. GEOLOGICAL SURVEY 11 9° 341 PROFESSIONAL PAPER 116 PLATE XXXVI 

/ 

• 2 

/ 

./ M. DONOHUE 

. a o7 

.2 l ... . 2 

• 13 • 3 . DOHENY !Ba •' •'* . s 17 . •' 

GRAY 

~ 

~--. 

JoH"Ns"ON- ··--

)+., ~ 

~· ·ki.JAL DO!ff-4 ··· ·. -··· ' 

~ 

., 

., . 2 . 6/ • .9 

<::> ~ •s ~ 

' lil II ' • o, 

~ <::> 7 

<::> 0 I (() ·c::. 

' !:: ,, () 

I I, () () 

I I ~ () 

I ~ ~ ' I I "- I I I I ) I I '/" I I 

I I I 

I I 

\ " -?- .... > \ 00 ' ' \ 

\ 

' •f'o \ \ 

' 0 \ ., 

• 8 • 7 •s, •5, ·r 

• • e 62 ::J II I • s2 • 4 \ 

. 53 -<-.9 eiJ3 3 • . 33 ASSOCI:{ED . 3 

~ 3 r ....... . : 

... <-3i 45 35 25 • i s 4i 0 • • 

• 

119° 34' 

SKETCH MAP SHOWING BY STRUCTURE CONTOURS THE UPPER SURFACE 

OF THE BOTTOM WATER SAND IN THE SOUTHEASTERN PART OF 

Wel ls are those 

shown on Plate Ill 

'r. 31 S., R. 22 E. , CALIFORNIA 

Surface contour interval 20 feet 

Structure contour interval!()() feet 

Datum iB mean ua letlel 

Mile 

--, '~N TO lAND DEPART' 

... ~i:fiA L f ET!;C LEU ,1 COR PO~ 

SAN FRANCISCO, CALIFC 

....................... 
GLOBE-BEAR CREEK AREA. 93 

Baume. ~1:ost of the heavier oil comes from 

the western part of the area, and the increase 

in specific gravity (decrease in degrees Baume) 

of the oil toward the west is evidently due to 

tb,e fact that. the oil produced there is derived 

in part from the B zone. The wells that are 

troubled with bottom· water yield oil 2° 

Baume or. so heavier than that '\vhich is norInally obtained fron1 the C'zone. 

SUGGESTIONS FOR FUTURE DEVELOPMENT. 

Deeper drilling.-It seems probable that 

throughout this area the C zone is in the basal 

part of the Etchegoin formation and that the 

success of deeper drilling depends upon the 

presence of oil sands in the Maricopa shal~. A 

few wells have been dril).ed through the water 

sand that underlies the C zone, and these wells 

show that below this bottom water there are no 

further oil sands on the south flank of the 

Globe anticline near the east-west ·center line 

of sees. 23 and 24. It is doubtful if any 

greater success will be attained on the north 

·flank of this same anticline. Any deep drilling 

must be carefully done in order that the water 

that lies.just below· the C zone shall be successfully cased off. A well to test the deep sands 

on the north flank of the fold should be placed 

a considerable distance ~ast of the ~'transition 

belt." It would therefore have to case off top 

water above the C zone, the C zone, and water 

below the C zone. 

· Exclusion o.fwater.from oilsands.-In two or 

tirree places in the "transition belt" where tar 

and water sands begin to appear in the B zone 

considerable trouble has been experienced in· 

handling top water because of the fact thatin 

adjacent wells the water strings have- been set 

at very different horizons. One of the areas 

where this trouble has occurred is near the 

southwest corner of sec. 13. Here a waterbearing sand occurs within the B zone; its 

position is shown in the geologic section on 

Plate XVI. Drillers of some 'wells here have 

reported this water and have cased off below 

it, thus casing this sand. off with the upper 

part of the B zone. Drillers of neighboring 

wells, however, have not recognized this water 

sn.nd and have set their water string at about 

the top of the B zone. 

It may be that this sand contains water in 

only a few place~ and that in the wells ·whose 

logs have not reported \vater the sand is 

actually dry. IIowever, as conditions now 

stand water is free to enter the sands in the 

upper part of the B zone in the wells that have 

been cased off below the water sand and to appear. in the wells that have been cased off above 

the B zone. Even though water has not yet 

appeared in the last-mentioned wells, it may do 

so later, when the oil has been partly extracted 

from the sand. · · 

A. condition that is similar to that ·just 

described and is concerned with either the same 

water sand as that .causing the trouble near the 

southwest ·corner of sec. 13 or with a sand at 

about the same horizon exists near the center 

of the west line of sec. 24. In some of the 

wells near the center of the S. ! sec. 14 the 

water string has been set below the top of the 

B zone, whereas in neighboring welll3 the water 

string is set much higher and the oil string is 

perforated to provide for the uppermost sands 

in the'B zone. Top water is thus free to enter 

the top of the B zone, although there is. no 

record of its actually having done so yet. 

In at least one well near the crest of the 

Globe anticline the water string has been set 

exceptionally low, apparently below the top of 

the C zone. It' is possible that top water is 

thus permitted to enter the C zone, and several 

of the wells in the vicinity of the well in which 

the casing is so set are ·troubled with water. 

The source of this water can no·t be stated 

definitely, however, for in this same a.rea 

bottom water was reached by the drill and it 

1:p.ay not have been plugged off successfully. · 

The sand that yields the moat water in this 

area is the one that closely underlies the C zone. 

The approximate poaition of the top of this sand 

is indicated 'by the contours on Plate XXXVI. 

These con tours ate of necessity only a rough 

approximation of the location of this sand, for 

the wells furnishing information as to its ·poaition are few and scattered. However, any well 

that is drilled below the horizon indica ted by 

these contours is in grave danger of encountering bottom water. The position of this sand 

is shown also on the geologic cross section. 

(Pl. XVI.) 

. GLOBE.:.BEAR CREEK AREA. 

[Sec. 15; W.! sec. 14; northwestern part of sec. 22; and 

NW. i sec. 23, T. 31 S., R. 22 E.] 

LOCATION AND. OPERATORS. 

. The Globe-Bear Creek area inCludes the ef(-

treme northwestern part of the North Midway 

field that was productive in 1916. (See geologic 

\ 
.. 

THE SUNSET-_MIDWAY OIL FIELD, CALIF.:..._PART ]. 

the beds only bend abruptly about the-ends of 

the plunging folds that'pass through sees. 6 and 

7, T. 31 S., R. 22 E. 

sections, Pls. XVI and XVII.) The companies 

operating here in 1916 were the Elliott, Bankline, Dominion, Potter, General Petroleum 

(Globe and Bear Creek), Kern Trading & Oil, 

Hondo, Midway Peerle3s, M. & M. (M. H. & M. OIL SANDS. 

and Cherokee), Security, Combined, Alberta The chief oil sands in this area lie in the lower 

Midway, M. G. & P., Pinal Dome, and Tull).- part of the Etchegoin formation, but it is probbador. · able that the· upper part of the productive. zone, 

GEOLOGY. or at least the lower part of the tar zone that 

The chief structural feature in theN. t sec. overlies the productive oil sands, is in the Paso 

15 is the fault that determines the eastern front Robles formation. Only one or two wells have 

of the Telephone Hills~ This fault dies out near been drilled completely through the Etchegoin 

line south end of those hills; and in the S. t into the underlying Maricopa shale, and the logs 

sec. 15 th~ beds are bent into several small of all these wells record oil sands mixed with 

· folds and broken by several small fault~. Near shell and brown shale, or "broken oil sand," 

the !Southeast corner of the section the structure for a,distance of about 200 feet below the. base 

is more simple, and the beds are folded upward of the Etchegoin. 

regularly, forming th~ fairly broad Glqbe anti- The oil sand~ vary in grain from very fine 

cline. sandy shale to pebbly coarse-grained sand but 

The chief structural features in the S.'! sec. slightly indtirated. "Shells". are not very 

15 are "(1) a gentle upward fold along a line abundant, but the clays in the lower part of the 

passing diagonally through the section and con- tar zone are thick enough to afford good landnecting the northwest end of the Globe anti- ings for the water string. 

cline with the southwest end of the fault zone In the western part of this area, in ~ec. 15, 

along the east front of the Telephone Hi&; the productive zone varies in thickness but 

(2) a slight downward fold along a parallel line reaches a maximUm. of about 400 feet. . The 

exte-nding, from the center of the west line to· upper liri:tit of the productive zone can not be 

the center of the south line of the section and recognized definitely from the well records, for 

probably continuing ·into the NE. ! sec. 22; the productive sands lie at the base of a thick 

(3) a very slight upward fold along a parallel zone whose upper pa~t is occupied by tar 

line that lies between the shallow syncline jrist sands, and not only does the impregnation of 

described and the Twenty-six syncline on the the different sands vary·considerablyfrom place 

south. These two last-mentioned folds are, to place, but the· drillers diffel! as to what 

however, so small and so broken by faults that should be considered a productive oil sand. 

individually they do not appear to have had Consequently, the bed recorded in the different 

rriuch effect upon the accumulation of oil, and well logs as the top of the productive zone is 

the upward· fold that extends diagonally not everywhere the same. Usually more care 

through the central part of sec. 15 may be was take~ to test the upper part of ·the zone 

. considered as the chief one of these minor s true- in the first wells drilled than in the wells drilled 

tural features. ·- · later, which were put down hastily to the most 

The rocks of the whole area from sec. 15 productive sand reached by .. the neighboring 

northward and westward to the outcrop of the wells. The logs of most of the wells in sec. 15 

diatomaceous shale in the Telephone Hills and record an almost unbroken oil sand; few of 

in the vicinity of the Santa Fe tank house in them record less than 200 feet, and most of 

sec. 17 are much fractured. Apparently there them between 200 and 300 feet. 

is here an abrupt twisting in the strike of the Toward the east the upper part of the probeds from thenorthwestward trend they have in ductive zone becomes more and more tarry, 

the foothills southwest of the Telephone Hills to and wells recently drilled near the east line of 

.an almost westward trend through the ~enter of sec .. 15 record only tar sands in the B zone. 

T .. 31 S., R. 22 E. It may be that a northeast- However, as far eastward as the centerofsec.14 

ward-trending fault of considerable size deter-:- the B zone has proved productive in spots, 

mines ·the low pass in the Diablo Range near and some of the first wells. in this section 

Crocker Springs, but it is m?re probable that originally obtained their oil exclusively from it. 
GLOBE-BEAR CREEK AREA. 95 

" . 

Were the B zone everywhere tested adeq~ately far enough above the top of the productive 

it might even now yield a small quantity of zone to be cased off easily. A lower ·topheavy oil throughoutthewesternpartofsec.14.· water sand encountered in sec. 14 and in part 

The chief oil sarids underlying theW. ! sec. 14 of the E.! sec. 15, about 600 feet-below the one 

are, however, in the C zone, and in the wells just mentioned, is found at the top of the B 

recently drilled the water strings have been zone ~nd, it is said, has not been shut off 

set near the base of the B zone, so as to pro- properly in some of the wells, probably. not 

duce oil from the lower sands. being recognized in maily of them.· 

Two wells have been drilled about 200 feet The chief tro11:ble from water is, as· usual, in 

below the base of the main oil sands of the the so-called transition belt that lies between 

Etchegoin in the western part of the area, ,th.e area in which oil i.s obtained from the 

penetrating the Maricopa shale. The logs of lower sand (the C zone) and that in which it is 

these wells record thin oil sands,. shale, and obtained from the top of the B zone, for it 

shell, but apparently no . water was encoun- invariably happens that in this belt the water 

tered. The oil sands have not proved to be strings are not set uniformly in the different 

productive. These sands, together with the wells. 

interstratified brow~ shales, have a total The very little top water .recorded in the 

thickness of about 100 feet and are s·eparated NW. i sec. 23 comes from a sand lying about 

from the base of the main oil zone . in the 200 feet above the top of the C zone. The 

Etchegoi1'1 by about an equal thickness of correlation of this sand is n.ot very good, but 

barren clay and shale. it may be the equivalent of the lower sand tl~at 

is as troublesome in the eastern part of sec.14. i:lEDS DEI...OW THE MAIN PRODUCTIVE ZONE. . (See p. 92.) 

Only three wells have certainly gone below Bottom water.-Bottom water has not been 

t4e Etchegoin, or, in other words, been drilled encountered in any well in sec. 15,even in the 

completely through the main productive zone.· deep wells th~t ha~e entered tlie Maricopa 

Below this zone were en~ountered ·numerous shale. It has been struck,· however, in some 

shells and brown shales mixed with lean oil of the wells in theW. ! sec. 14, particularly in· 

sands. These beds form the upper part of the several wells near the center of the south line 

Maricopa shale, which here is coarse grained of sec. 14.. This water is discussed in detail 

and of much the same character as it is where in the part of this report describing the E. t 

exposed in the hills west of. Fellows.. sec. 14, the NE. i sec. 23, etc. (p. 92). Its 

wATER SANDS. approximate position is shown by the contours 

on Plate V . and in the geologic section (Pl. 

XVIII). Top ivater.-Top water has not proved 

troublesome in the western part of. this areathat is, in most of sec. 15-and only a f~w of 

the wells, most of them in the easterll.part of the 

SE. i a~d the W. ! sec. 14, record top water. 

This water sand is interstratified with tar sands 

and lies about 400 feet below .the surface and 

300 feet above the top of the B zone.1 The 

water in one well is said to be practically fresh 

and is evidently only surface drainage. 

Near the east line of sec. 15 top water appears 

lower down, apparently occupying sands· in the 

upper part of the tar zone-that is, in the 

uppe1~most part of the zone that is prod~ctive 

in sec. 15. 

In general the top water encountered in the 

western part of sec. 15 is largely surface drainage and should not be troublesome, for it is 

1 Sco aualysh! 7, 'l'ablo 14, Part II (Prof. Paper 117). 

CHARACTER OF THE OIL. 

Most of the oil obtained in se~. 15 ranges in 

gravity from about 12° Baume to _about 16° 

Baume, but in places a little oil of relatively 

light gravity (17° to 18° Baume) is recorded 

in sands that lie at the very top of the productive zone. The oil from the bottom sand 

is in much of the area exceedingly heavy, and 

in many places it has been found difficult or 

almost impossible to drill through this tar sand 

with standard tools. The logs of many of the 

wells record alteri,lating oil sands and tar sands. 

It is probable that the variation in gravity is 

caused by the fractured nature of the beds 

and their variation in grain, rather than by 

the presence of water, the ·very coarse beds 

retaining only the tarry oil, whereas in the 
96 THE SUNSET-MIDWAY OIL FIELD,· CALIF.-PART I. 

fine-grained and less fractured beds fractiona- zone. This method would be all right if the 

tion is less complete and the lighter oil is drillers' ideas were all alike, but unfortunately 

found. It is. also probable that along the ·in some wells in theW. t sec. 14 the casing has 

faults only tarry oil remains; the lighter con- been set above the lower of the two top-water 

stituents havillg left. · sands described above, an~ in neighboring 

In the western part of s·ec. 14 and the NW. i wells below this water sand. 

sec .. 23 the oil is slightly lighter, the lightest · SUGGESTIONS FOR FUTURE DEVELOPMENT. gravity· recorded being between 20° and 23°. 

This oil, ·however, probably com~s· in part at 

least from the lower or C zone. 

PRODUCTION. 

Deeper drilling.-On the whole it seems foolish 

to drill deep wells here in the hope of getting oil 

from sands that lie below the zone that ia now 

productive, especially in the western part of 

Most of the wells in sec. 15 came in as pump- the area-that is, in sec. 15. The zone that is 

ing well:;, making 100 to 300 barrels. They are now yi~lding oil appears to be almdst if not 

fairly long-lived, .or ae least the rate of de- quite at the base .of the Etchegoin. The Maricrease is not very great for the :first two or copa shale, upon which the Etchegoin rests, is 

three years. In the ·western part of sec. 14 made up of diatomaceous shale w!th intercfi:-

and the NW. i sec. 23 ,many of the wells flowed lated lenses of granitic sand and gravel. The 

originally and have made 300 to 400 barrels or coarse. lenses may yield some oil, yet the opmore a day. The period during which they portunity for the oil to have migrated into the 

flowed, however, was not very long and the overlying Etchegoin is so great, owing to the 

de.crease is much more rapid than for the unconf<?nnable relations existing. between the 

pumping wells in sec .. 15. The reason for this Etchegoin and the Maricopa shale, that the 

difference is to be found in the fact that in sec. coarse beds in .the Maricopa shale are rather un15 the·productive zone is thick, whereas in the promising. . , . 

e·astern part of the area the sands yielding · As the Etchegoin. thickens· toward the east, 

oil are much thinner and ·either the ca.3ing has owing to the unconformity at the base of that 

not been perfor.ated for the upper part of the formation and the inclusion in' it of older. beds 

zone found to be produc~ive in sec. 15 or else than those present closer to the outcrqp, it is 

this part has been shown to be a tar sand that possible that eastward from the vicinity of the 

will yield no oil. It ia probable that if the upper east line of sec. 15 a 4eep sand may lie below 

part of the productive zone had been more the zone which is now yielding oil. The procarefully tested in the we3tern part of sec. 14, ductive zone is, however, underlain in thiS part 

it might have yielded a considerab~e amount of of the field by a persistent sand carrying 

heavy oil. · saline water, and in drilling through this water· 

Near the outcrop in sec. 15 the tar sands and sand great ·care must be exercised .to ·prevent 

ev-en some of. ~he sands containing heavy· oil the infiltration of the water into· the overlying . 

· are so sticky .that drilling ·with standard tools. productiv<:f"oil sands. 

is slow and unsatisfactory, and consequently Although the Etchegoin thickens eastward, 

many of the new wells have been drilled with the 'rate of thickening is not very great, and 

the rotary rig .. ·Thia in a measure acco1p1ts for inasmuch as wells in the E. t s~c. 15 that have 

. the difficulty in making satisfactory correla- been drilled through the productive zone have 

tions from the drill records, for it is notoriously not encountered a deeper sand, it would seem 

difficult to keep an accurate log of a rotary best, if the drilling of a deep well in sec. 14 

drilled well. were contemplated, to place that well someA few of the wells in sec. 15 use but a single where .in the E. t sec. 14 or even in sec. 13, 

string of casing. This is safe only near the where a sufficient thickness of beds to contain 

western edge of _sec. 15, for DJ.any of the wells a workable oil sand may have wedged in benear the center of the E. t SW. i get a top water low the present productive zone. and above the 

which, although only ·surface drainage, should Maricopa shale. The prospect of obtaining 

be kept out of the productive sand. In most of deeper sands in this general area is discussed in 

the other wells a water string is set just above the section dealing with the E. t sec. 14, the 

the top of what is considered the productive NE. ! sec. 23, !3tc. (p. 93). · 
THE SUNSET-MIDWAY OIL :FIELD, CALIF.-PART I. 97 

TRAFFIC-STARLIGHT AREA. the l.ower part of this zone or, more probably, 

. is absent the' sands forming it having been [Sec. Hl; eastern part of sec. 17; northeastern part of sec. ' · 

· 20; all of sec. 2l. except the southwest corner; and all.of cut out along the plane of unconformity that 

sec. 22 except the nortl~eastcrn part, '1'. 31 S., R. 22 E.] marks the. base of the Etchegoin. It may be 

LOCATION AND WELLS. 

_ · that the C zone extends as far west as the 

center of the east line of sec. 22, for the lower. 

part of the productive ·zone encountered in the 

Chanslor-Canfield Midway Oil Co.'s well 

No .. 2 in that section corresponds in general 

position fairly well with that zone. 

The Traffic-Starlight area lies at the extreme northwest end of the North Midway field, 

just west of the south end of the .Telephone 

I-Iills. It extends from the outcrop of the basal 

beds of the MciGttrick group eastward to 

the vicinity of the . area in sec. 15 which in 

1916 was producing oil. There are no producing wells in this area, but there are several 

idle or abandoned ones, in some of which oil 

was et.coun tered. Chief among these are the 

wells of the State Consolidated and Corrigan 

oil .companies in seo. 17, the Durango Oil Co. 

in ~ec. 20, and the Starlight, K. & C., and 

Chanslor-Canfield :Midway Oil companies 1n 

sec. 22. 

GEOLOGY. 

The dominant structural feature in this 

area is the Twenty-six syncline, which trends 

diagonally northwestward through sec. 22 

from a point a little south of the cen~er of the 

east line of that section and is continued by a 

general synclinal structure through sec. 16. 

This syncline appeal'S to be a. well~defined 

trough in sec. 22, with fairly steep dips O:t:J. 

both north n:nd south flanks and, near the 

east line of the section, a strong plunge toward 

the east. Toward the northwest, however, 

the regularity of the trough is broken by faults, 

and in sec. 16 no ·line marking ·the center of 

the trough can be drawn. 

The axis of the Globe anticline passes close 

to the northeast corner of sec. 22, but it is here 

not the dominating feature that it is farther to 

the southeast, fo1· it commences to break up 

into a number of small folds and faults. The 

anticlines and synclines occupy the western 

part of sec. 17 (see geologic map, Pl. II), 

plunge rather abruptly eastward, and do not 

affect the structure markedly in the W. ! 

sec. 16. They proba.bly have no particular 

iilfluence on the accumulation of oil in this 

area. 

OIL SANDS. 

In this n:rea only a single t:P,ick productive 

zone can be, recognized. The C zone, which 

is productive in the E. ! sec. 23, either fo~ms 

109288°-10-7 . 

· The conditions encountered in the SE. i 

sec. 15 (see pp. 9~-96) probably prevail as far 

west as the center of theSE. 1 sec. 16, for here 

the productive zone is about 150 feet thick. 

The sands become markedly thinner, however, · 

westward. from this locality, probably owing 

to the unconformity at the base of the Etchego~n, and in sec. 17 the zone containing sands 

is not much over 100 feet thick, 9f which less 

than 50 feet is probably truly 00.1 sand. Toward 

the southwest, in the N. ! . sec. 21, thick oil 

sands are reported. They evidently contain 

very heavy oil and will probably not prove . 

very productive, as there is in that vicinity no 

dominant fold along which oil would tend to 

collect. · 

One or two of the wells in this area have 

been drilled completely through the ma.i~ oil 

zone of the Etchegoin into the underlying 

Maricopa shale and in this formation have 

found irregular lenses of sand, ~orne containing a little oil and some containing water. 

The chi~f water sand reported seems, to underlie closelY. the main oil zone at the base of the· 

·Etchegoin. 

FUTURE DEVELOPMENT. 

Much of the area lying northeast of tlw outcrop of the Maricopa shale in sees. 21 and 22', 

possibly a very small part of sec. 20 and of the 

SE. 1 sec. 17, ~nd a considerable part of the 

S. ! ·sec. 16 Wiill .probably prove productive. 

In the SE. 1 sec. 16 the oil will be found· in 

the thick oil sands under much the same conditions as are encountered in the SW. 1 sec. 

15, but the productiveness of the sand will 

probably decrease westward from· the vicinity 

of the wells now producing in sec. 15. 

On the south flank of the Twenty-six syncline, in the. area passing diagonally through 

the· S. t sec. 22 and,· probably_ extending into 

the N. ! sec. 21, the oil sands will probably 

be found to have much the same character as 
98 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

those in the SW.! sec. 26-that· is, they are 

100 to 300 feet thick, are coarse grained, and 

will yield a heavy oil. The most promising 

part of this belt lies about midway between the 

outcrop of the McKittrick group and the axis 

of the Twenty-six syncline. Close to the outcrop the productive zone contains chiefly tar 

sands, whereas near the axis of the· syncline 

water will probably appear in the productive 

zone. Wells drilled.in this part of the area will 

almost certainly not be so productive as those 

in the SW. l sec. 26, for in general the south 

flank of the Twenty-six syncline becomes less 

promising northwestward from the west line 

of sec. 26. · 

There is but little probability that the Maricopa shale contains extensive produetive oil 

sands. Oil may occur in isolat·ed lenses in this 

formation, but the wells that have been drilled 

into it have found only water sand and a few 

very poor oil sands. 

is a regular, fairly narrowtrougn as· far southeast 

as the vicinity of the center of the north line 

of sec. 26, but eastward from that locality it 

plunges rather abruptly and swings from a 

southeasterly trend to an almost easterly one, 

thus paralleling the Globe anticline. Near the 

northeast corner of sec. 25 the syncline has 

almost flattened out, as is shown by the very 

slight embayment made by the underground 

contours (Pl. III). 

' The Twenty-six syncline is really the western 

of the two branches of the Midway Valley 

syncline.. It may almost be considered as the 

main arm of this branching trough, for the 

saddle between the Globe anticline and the 

United anticline is probably. s~ high a~ practically to terminate the north arm of the MidwayValleysynclineinsec. 19, T. 31 S., R. 23 E. l' 

OIL SANDS. 

The ,chief production in this area is obtained 

from the· C zone, the upper or B zone being 

dry in most of the area. The ·c zone is entfrely in the Etchegoin, as is shown by the 

fossils, which are very plentiful in the producing sands, especially along the east line of 

sec. 23. 

The beds containing oil range from a pebbly 

sand in which the largest fragments are between 

a quarter and half an inch in diameter to a very [S.! sec. 23; SW. tand E.~ SE. tsec. 24; NW. tand W. ~ 

NE. ·t sec. 25; NE. t and northeastern part of NW. l fine sand or sandy clay. One of the most proOn the whole, wells drilled in this area will 

probably yield only a small amount of heavy 

oil. The most promising parts of the. area lie 

along .the flanks of the Twenty-:-six ·syncline 

and probably also along the axis of that syncline near its west end, in sees. 21 and 16. 

BROOKSHmE-GEM AREA. 

sec; 26, ?-'· 31 S., R. 22 E.] ductive wells in this area obtains its oil from. a 

' LOCATION AND OPERATORS •. 

_ The Brookshire-Gem area includes the southern part of the North Midway field, extending 

from the westernmost part of the field that 

was· producirig oil in 1916 as far eastward as 

•the deep wells north of Fellows, along the 

west lme ofT. 31 S., R. 23 E. (See geologic 

section, Pl. ~VII.) The companies operating 

here in 1916 were the Tumbador, Pinal Dome 

(Gem), Rock, General Petroleum (Logan and 

Brun~wick), Brookshire, San Francisco Midway, 

· United, Coalinga Monterey, Kern Trading· & 

Oil (sees. 23 and 25), Midland Oilfields (Ltd.), 

Chansior~Canfield Midway Oil .(sees: 25 and 

26), Resui~, El Camino, ·and. Pyramid. 

GEOLOGY. 

"pepper and salt" sand in which the grains 

are of exceptionally uniform size and well 

rounded. Most of the :wells, however, including all that have yielded only a small quantity of oil, obtain their oil from a very 

uneven-grained sand which contains a large 

amount of clay ~nd in which the free-pore 

space is evidently small. 

The C zone·is the chief producer, the upper· 

or B zone being recognized and the casing perforated for it only in the SW. !.sec. 23 and the 

NW.! sec .. 26. The C zone varies in thickness; 

the m,aximum is ab.out 200 feet, including interstratified barren clays and san&. The oil sands 

themselves are usually less than 100 feet and 

in places only 10 to 25 feet thick. On the average about 30 to 40 per cent of the C zone is 

recorded rJs oil sand. 

This area lies along the central part of the The "transition belt" that marks the eastTwenty-six syncline and extends up the north ernmost. extension of the area beneath which 

flank of that syncline nearly to. the. crest of the B zone contains some oil extends roughly 

the Globe anticline. The Twenty-six syncline along the north-south center line of sec. 23 to 
BROOKSHIRE-GEM AREA. 99 

the vicinity of the south line of that section. 

There it swings slightly to the west and, bending about the Twenty-six syncline, tren~a 

southeastward practically through the center 

of sec. 26. In the "transition belt" the productive beds have a maximum thickness of 

450 feet, the lower part of this embracing the 

C zo'ue. ''Stray" oil sands occur in the B 'zone 

as far east as the north line of sec. 25, where a 

sand containing some oil lies about 200 feet 

above the main 0 zone. This "stray" sand is 

remarkably coarse grained, being very much 

coarser than the sands -in the 0 zone beneath. 

Along the east line of the NE. i sec. 23 the 

B zone is 70 feet thick and is separated by 200 

feet of clay from the 0 zone, which is here 120 

feet thick. The B zone here contains tar, not 

oil, but may be recognized. definitely. Near 

the east line of sec. 25 the beds in the upper part 

of the 0 zone beconie less productive, the main 

pi·oduction. coming from the lower part, 

although one or two wells are a notable .exception tb this generul rule, for they, apparently 

get their oil from the very top of .the 0 zone. 

BEDS ABOVE THE B ZONE. 

course, a great many barren clays, hardly 40 

per cent of the beds being recorded as tar sand, 

In the ·northern part of sec. 25 the logs of 

only a few of 'the wells record a thick tar sand, 

and most of them record only irregular tar 

sands; but -these sands occur within 600 feet 

of the surface, even where the productive oil 

sand lies at a depth of fully 2,400 feet. 

BEDS BELOW THE C ZONE. 

The C zone is in the basal part of the Etchegoin formation probably throughout the area 

and certainly in the northern and western parts 

of it.. A few wells that have been drilled several hundred feet below the base of the C zone 

have entered the Maricopa shale, and their logs 

record shale and numerous shells (many of 

which are recorded as "lime shells") and 

abundant water sands. One . of these wells 

encountered an oil sand in. the ¥aricopa shale 

but never produced from it, the sand being shut 

off on account of water trouble. 

WATER SANDS. 

Bottom water.~The 0 zone is underlain by 

water sand throughout the area. The top of 

The beds above the B zone consist of the this sand is shown approximately by the con-. 

usual mixture of clay, sand, and gravel. All tour map (Pl. XXXVI). The sand is the same 

the wells were drilled with rotary tools, and. as that encountered by many wells in the 

the upper parts of many of the logs are not southern part of sec. 14. However, in the area 

intelligible. It seems, however, that the beds under discussion it is separated from the botas a whole are somewhat coarser grained than· tom of the 0 zone by a somewhat greater thickusual. .Also it is certain ·that tar sands are ness of clay than it is in sec. 14, for in general, 

more abundant here than in other parts of as is shown in the geologic section (Pl. XVI), 

the field that contain the oil sands b:uried at an tbis bottom water sand seems to diverge 

equal depth, for they are almost as thick here slightly from the 0 zone toward tl;le southeast. 

as they are in sec. 15 of the same township, For example, near the center of th~ north line 

where the productive zone is buried under of sec. 23 the bottom of the C zone is practically 

niuch less cover. in contaqt with this· water sand, 'Yhereas near 

rrru· sands are remru·kably thick along the the center of sec. 23 some 50 feet or so of clay 

east-west center line of sec. 23, where about separates the oil sands from the underlying water 

hnlf the beds that lie between the top of the B sand. Near the center of sec. 26 the water 

zone and a point 700 feet above that zone are sand is barely 100 feet below the top of ~he C 

saturated with tar. In two of the wells tar sands zone and there is ve.ry little clay between the 

ru·e reported wit~ 200 feet of .. the surface. two, ,the conditions here practi.cal~y duplicating 

Along the south line of sec. 23 the tru· sands those near the center of the north line of sec. 23. 

are nnlCh thlnner than they·are in the center Near the the center of the east line of sec. 23 

of that sec'tion. I-Iere they may be grouped the water is fully 120 feet below the top of the 

roughly into two zones. The upper tar zone is 0 zone, wbich is there 50 feet. thick. At the 

150 to 200 feet thick and its top lies 600 to 800 center of the east line of sec~ 26 the C zone rests 

feet below the s~rface. The top of the lower practically upon the water sand. 

tar sand lies 300 to 600 feet below the bottom. of Top water.-Top water is not troublesome in 

tho upper sand and extends down to the top of the western part of tbis area, practically the· 

the D zone.c Tbis lower zone includes, of only water ~ncountered there being either dis-
100 THE SUNSET-MIDWAY·OIL FIELD, CALIF.-PART I.. 

tinctly surface water or so far up in the tar 

:sands that it is always cased off." There are 

·very few data as to the strength of flow. or 

·quality of this water, but it is said to be 

·"sulphur water." 'Water appears in the upper 

part of the· B zone in the east~rn half of the 

area; and in the easternmost part practically 

all the B zone is occupied by water.1 A line 

drawn from the Kern Trading & Oil Co.'s well 

No. 12, in sec. 23, and trending S. 25° W. to the 

vicinity of General Petroleum (Brunswick) No. 

1-A, in sec. 26, separates roughly the area on 

the southeast in which the B zone is occupied, 

·wholly or in part, by water from that on the 

northwest in which no water is recorded in that 

sand. On the south funb of the Twenty-six 

syncline the line marking the western l.irpit of 

the area in which the B zone contains abundant 

~ater trends. f?Outhea8tward and passes. just 

south of the Chanslor-CanfieldMidway Oil Co.'s 

well·No. 2, in sec. 25. The log of only one well 

northwest of this line sho,ws water in the B 

zone, but this 1og is not very reliable, and water 

. may not actually have been encountered. This 

top water is what was called the "lower top 

water, in the description of the southwestern 

·part of sec. 13·, and its position is shown on the 

geologic section (Pl. XVI). 

CHARACTER OF. THE OIL. 

The oil ranges in gravity fr~m 16° to 23° 

Baume, and the lightest oil comes from the· 

very top of, the C zone near the eastern edge of 

this area. The heaviest oil is almost invariably 

that obtained from wells which either are in 

bottom water the~selves or are adjacent to 

wells that are. ·The normal oil from the. C 

zone appears to run about 21 o to 23° Baume. 

In the eastern part of sec. 25 the top ·of the C 

zone is either dry or contains only a little oil, 

the production coming from the lower· part, 

and the oil from this .part of the C · zone is 

several degrees heavier than that in the uppermost part. · 

PRODUCTION. 

This area is one ·of the ·most spotted ih the 

whole Sunset-Midway' field .. There is nothing 

in the structure of the area ·that makes-It a 

specially favorable locality for the concentration of oil, for it lies along the axial part of 

a well-marked syncline, and oil would tend to 

migrate either to the north toward the crest 

of the Globe anticline or to the southwest into 

1 See analysis 40, Table 21, Po.rt II (Prof. Po.per 117). 

the beds· on the steep riqrth flank of the Midway 

anticline. As is described above, the grain of 

the oil sand is variable, the sand being in some 

places very porous and in others clayey and of 

a low degree of porosity. It is this variable 

porosity that appears to govern the accumulation of oil,. which is trapped in the coarser 

lenses. About four large wells were obtained 

in. this area, and these are scattered through it. 

Between them were brought in wells which 

made less than 100 barrels a day initially. In 

1914 the average production per well per day 

was about 30 barrels for the northern half of· the 

area and about 60 barrels for the southern half. 

FUTURE DEVELOPMENT. 

Except in the northwestern part of this area· 

the success of all future development is dependent upon the C zone, for it is improbable that 

any deeper sand occurs here except possibly in 

the very easternmost part. Even there such 

deep sands are probably to be considered as 

nothing more than the lower· part of the C zone, 

for that zone thickens toward the east owing to 

the unconformity at the base of the Etchgoin 

and the wedging in of beds above the diatomaceous shale and below the lowest· Etchgoin 

present in the western part of the area. In the 

northern part of the area, on account of the 

fact that the water sand so closely underlies the 

C zone in the Globe anticline, it is risky to drill 

deeper than 100 feet belqw the top of that zone. 

In the southeastern part of the area the water 

sand is separated from the C zone by a greater 

thickness of clay, ·and the margin of safety is 

greater. (See Pl. XXXVI for approximate 

location of this water sand.) In drilling for 

lenses in the l\1aricopa shale care must be 

taken before testing such lenses 'to case off · 

top water, the C zone, and the persistent water 

sand that lies just.below the C zone. 

In the eastern part of the area the upper or 

B zone is occupied wholly or in part by water 

and must be cased off. Only in the northwestern part of the area may oil be obtained 

from this zone. 

EL CAMINO-PIONEER MIDWA~ AREA. 

[Central part of sec. 26; N. ! S. ! and southern edge of 

N. ! sec. 25, T. 31.8., R. 22 E., and west-central part 

of sec. 30, T. 31 S., R. 23 E.] 

LOCATION AND OPERATORS. 

The El Camino-Pioneer Midway area extends from_ the- extreme western edge of the 

present productive field to a point about a 
EL CAMINO-PIONEER MIDWAY AREA. 101. 

mile northwest of the town of Fellows and 

forms a belt 3,000 to 4,000 feet wide far down 

on·the north limb of the Midway anticline, or, 

in other words,· on the south flank of the 

Twenty-si.x syncline. The companies operating here in 1916 were the El Camino, Pyramid, Stu.te, Soudan, Chansior-Can:field Midway 

Oil (sees. 25 and 26), Kern Trading & Oil, 

and Associated (Pioneer :Midway). 

GEOLOGY. 

This area lies well qown on the north flank 

of the Midway anticline, where the beds usually dip less than 10°. The Twenty-six syncline, whose n.xis lies just north of this area, 

plunges abruptly· eastward and is lost near the 

enst line of the area-that ·is, near. the· east 

line ofT. 31 S., R. 22 E.-there merging with 

the main structural depression of the Midway 

V nlley syncline. 

The southeastern part of sec. 25 more closely 

resembles the area lying 'farther southeast--

that is, the northeastern part of sec. 36 and 

the northwestern part of sec. 31-and it is described in detail in the discussion of those 

areas (pp. 106-110). 

OIL SANDS. 

The. producing oil sands in this area occur 

in the lower part of the McKittrick group in 

the Etchegoin formati_on. Some oil sands 

have been encountered in. the underlying 

Maricop~ shale in one or two of the deep wells, 

but so far these sarids have not yielded much 

if any oil. 

The western part of the area· embraces what 

has been described as the "tru.nsition belt," 

where the chief production is obtained from 

the C 'zone but where the overlying B zone 

contains oil, as well as tar and water. The 

total thickness of beds from the top of the B 

zone to the base of the C zone is about 300 

feet, and of tlris apl?roxin1ately the lowest 100 

feet constitutes the 0 zone. In places the oil 

sands reported in the C zone are very thin, 

some of the wells reporting not more than 20 

feet of them. · 

In the eastern part of sel!. 25 the B zone 

contains no oil, the productive sands occurring 

entirely within the C zone, which is·here about 

200 feet thick. The sandy beds inc~uded in 

this . zone in this pu.rt of the field are very 

lenticular and probably of much the same 

character as those composing this zone near 

the north line of sec. 25, as describ{}d on 

page 98. 'fhe general character of the c zone· 

here is about as follows: 

General section of C zone in E. ! sec. 25, T. 81 S., R. 22 E. 

Blue sandy shale containing numerous "shells" 

and some lenses of sand which have yielded the 

oil produced by the larger wells here. These 

lenses are, however, of small areal extent ....... . 

Blue shale barren of oil._ ...... _._ .............. . Oil sand . _ .... _ . _ . _ . _________ . ___ . _ . _ . _ . _ . _ ... _ . 

Sandy shale; contains some oil in small lenses ...... . 

Oil sand ............ _ . _ . _ ...................... . 

Feet •. 

50' 

50 

10 

70 

30 

Most of the wells here derive theit· oil from 

. the two lower sands. 

BEDS ABOVE THE B ZONE. 

In the western part of the area the B zone 

is overlain by thick tar sands which are 

reported to extend within 500 or 6oo feet of the: 

surfrtce. The tott\1 thickness of the zone: 

containing. them is between 700 and 1,000 feet, 

of which the sands saturated with tar form less 

than 20 to 40 per ce!lt, the remainder being 

clay, etc. In the eastern part of the area tar 

sands are reported· to occur about 800 feet, 

or so from the surface, but strangely enough. 

below this upper tar zone very few tars are 

reported down to the C zone. It may be, of 

course, that, as many of 'these wells· were. 

drilled with rotary tools, tar sands were not·. 

reported, but the difference .in the records of 

the tar sands encountered in the wells drilled 

in the eastern part of sec. 25 from those m 

the western part of the area· is. s'triking. 

BEDS BELOW THE C ZON~. 

Only one well has been drilled for a considerable depth below the C zone, but several of the 

wells have been drilled into the water sand 

which immediately underlies that zone. The. 

log of the deep well records brown shale, shell, 

and sandy shale below the C zone and an oil 

sand about 300 feet below the top of that zone .. 

This oil sand is clearly a sandy lens in the 

Maricopa shale, which here seems to be considerably more sandy than usual, and resembles 

the beds that crop out in the upper part of the 

Maricopa shale west of Fellows. 

WATER SANDS. 

Bottom water.-Throughout the area the C 

zone is underlain fairly closely by a water sand, 

into which eight or nine wells have been drilled.1 

1 See analyses in Table 21, Part II (Prof. Paper 117). 
102 THE SUNSET-MIDWAY OIL FIELD,· CALIF.-PART I. 

In . the eastern part of sec. 26 this water 

sand,lies about 100 feet below the top of the 

C zone and in some places is reported immediately below the oil sand~ . whereas in other 

places 'about 50 feet of shale is reported between 

the oil and water sands. Toward the east the 

barren strata separating the water. sand from 

the lowest productive oil. sand in the overlying 

C zone increases in thickness; and near the east 

line of sec. 25 the top of the water s~.nd, as 

nearly as may be judged from the very meager 

data available, is between 200 and ioo feet 

below the top' of the C zone. The location of 

the top of this water sand is shown approximately by the contour map (Pl. XXXVI) . 

. Top water.-Top water is reported in most of 

the wells· several hundred feet above the productive C zone. · Water sands are reported also 

either in the top of ·the B zone or just abo~e it, 

in wells near the center of sec. 26, in ·.the 

"transition belt." 

CHARACTER OF THE OIL. 

this area. Several other ·wells had a "settled" 

production between 100 and 400 barrels daily. 

SUGGESTIONS FOR FUTURE WORK. 

Water sand underlies the productive zone 

throughout this area and in the western part 

appears to be very close beneath it. In the 

eastern part of the area bottom water has not 

been reaohed, but heavy oil in the lower part 

of the C zone may indicate that the water is 

not far below. In any case it is risky to drill 

more than 100 fee~ or so below the top of the 

C zone. · 

On the whole it appears probable that the 

average production of wells drilled in the future 

in this area will be low, but that wells having 

a fairly large daily production may be oqtained 

in a few places. On account of the lenticular 

oharact·er of the oil sands, it is probable that 

the big wells here will have less effect upon one 

another than in most parts of the field, and 

that wells of fairly high pressure will .be obtained even after the. field is pretty well drilled 

In the ·western part of the area, where most up. However, the life of these wells will not 

· of the oil is obtained from the B zone, the oil be long. 

is much like that found in the southern part of. STATE-AMERICAN OILFIELDS AREA. 

the SW. t sec. 26, higher up the flank of the 

Midway anticline, ranging in gravity from 14o [Southwestern part of sec. 26; northeastern part of sec. 27; 

northeastern part of sec; 35; southwestern part of sec. 36, Baume or a little heavier to about 18° Baume. · T. 31 S .• R. 22 E.; north edge of sec. 1, T. 32 s .. R. 22 

In the eastern part of the area, where the C E.; ,southwest corner of sec. 31, T.31 S., R. 23 E.; and 

zone furnishes the production, the oil has an northwest corner of sec. 6, T. 32. S., R. 23 E.] 

averag·e gravity of ·about 22° Baume. In 

places, notably in the easternmost part of the 

area, where the ·oil. comes from· the lower part 

of the C zone, it ,is somewhat heavier-18° to 

19° B'aume .. The upper part of the C zone 

here apparently. contains light oil, where it 

contains any oil at all, and has· yielded the 

.g~her flow in the Associated well (Pioneer 

Midw.ay No. 2). · The heavy oil in the lower 

part.of the C zone may indicate the presence 

of bottom water close below, or it may be that 

the lower beds are somewhat coarser grained. 

PRODUCTION. 

The production of wells drilled. in tliis . area 

varies greatly, the reason probably being that 

the oil sands are lenticular and in much of the 

area are so clayey that they do not contain 

much oil. Certain coarse lenses,· however, contained grea~ quantities of oil; and one. of the 

largest producing wells in the .field (Pioneer 

Midway No. 2) is near the. e8$tern margin of 

LOCATION AND OPERATORS. 

The· State-American Oilfields area extends 

fro~ the outskirts of the town of Fellows wes~ 

ward to the western edge of the developed field. 

and embraces a belt about 4,000 feet wide just 

northeast of the outcrop of the main oil sands. 

(See· stereogram, Pl. XXXVII.) The chief 

compani~s operating here in 1916 were the El 

Camino, California Star, State, Mocal, Pyramid, 

Associated, Chanslor-Canfield Midway Oil, 

American Oilfielda, United, Eagle Creek, . and 

Mammoth. 

GEOLOGY •. 

The dominant structural feature here is the 

Midway anticline, which trends ~lmost due 

southeast through the oenter of 0 sec. 35 and 

takes a somewhat more easterly course through 

the N. ! sec. 1 into sec. 6. At the surface the 

fold; is fairly sharp; the· basal beds of the 

McKittrick group, which crop out near the axis 

of the fold, being tilte.d to angle~ of 25° or 30°, 
STATE-AMERICAN OILFIELDS AREA. 103 

and the underlying Maricopa shale, whioh is an inch or so in diameter to fine sand or sandy 

exposed in plaoes along the axis of the fold, shale. Some of the beds, particularly those in 

even more steeply. The belt of steep dip is the south end of the area, where the fossilifernarrow, however, extending in few placea more ous beds described above occur, are indW'ated 

than 500 or 1,000 feet northeastward from the by a lime cement. For the most part the oil 

axis of the fold, and beyond it to the northe~t sands in the western half of the area a:re fairly 

the beds dip at angles of 10=> or less. · fine grained, but they seem to be relatively 

Like most of the other. folds in the foothills, free from clay.· .Very few samples of sand con- · 

the :Midway antiCline flattens greatly at a depth tain grains that will not pass a 20-mesh sieve, 

of a few hundred feet, and the oil sands are not and a ver-y large part of each sample passes an 

buckled ~early so sharply as the beds that crop SO-mesh sieve. In places ~he sand C01;ltains 

out. 'The Midway anticline extends.~ short fragments of a quarter of an inch in diaineter, 

distance farther northwestward than is shoWJ;l but these fragments are not common and it is 

on the rnaps (Pls. II and III). In sees. 26, 35, notable that the samples in whioh they occW' 

and the northwestern part of sec. 1 the· crest of usually contain ·a large proportion of clay. 

the :Midway anticline appears to be about hori- The· s,ands yielding the most oil usually are 

zontal, but eastward from that locality the fold even-grained "pepper and salt'' sand in which 

plunges abruptly to the southeast. · the grains are well rounded. · The lower part of 

OIL SANDS. 

The chief productive sands. in this area lie 

entirely within the Etchegoin forma~ion, as is 

s.hown clearly by the fos.~ils that they contain 

from top to bottom. The Paso Robles formation contains tar but no productive oil sands. 

The Maricopa shale has been penetrated by one 

or two wells and is reported to contain a few 

oil sands, but these appear to be lenticular, 

~mall, and unimportant and have yielded a 

very small fraction of the total production. 

Although most of these lenses are practically 

negligible as a commercial source of oil, the 

Maricopa shale contains commercial amounts 

·of oil in certain place~, for where its uppermost 

bedc; are sandy they form the lower part of the 

main productive zone. I 

The fossiliferous beds of the Etchegoin orop 

out in sees. 35, 36, 1, and 6, this being one of 

the few plaoes where the Etchegoin is exposed 

in the Midway field. · The belt of outcrop is so 

·narrow that it has not been shown on the 

geologic map (Pl. -II), but its appropriate position is indicated on the map showing the underground contours (Pl. III). The fossiliferous 

beds that crop out are evidently the beds from 

which the oil in the northwest corner of sec. 6 

is obtained, many fragments of fossiliferous 

sand hav:Jng been blown out of the United 

Oil Co.'s well No. 9 when it firs.t entered the 

sand. 

The oil sands here range from pebbly sandstones in which the larger fragments are half 

the productive zone-that is, the basal part of 

the Etchegoin-does not appear to be markedly 

coarser than the upper part. 

The. productive zone is thickest in the northeastern part of the area, where it is usually 

about 300 feet thick, although in one or two 

wells oil sands are· reported through a zone 

fully 400 feet thick. The lowest· oil sap.ds encountered in the wells recording this maximum 

thickness are, however, probably in tlie Maricopa shale, which is in certain places very 

sandy near the top. In most of the wells, the 

greater part of this zone is recorded as oil sands, 

some of which are more and some less productive; in many wells barely 5 per cent of the 

whole is said to be entirely barren of oil. It is 

therefore impossible to separate the. zone into 

parts comparable with the B and C zones of the 

area .farther from the outcrop_. 

Within 1,200 or 1 ,5.00 feet of the. Oll;tcrop 

the productive zone is not oy-er 100 feet thick, 

and the productive well closest to the outcrop 

usually encounters only 40 to 50 feet of oil sand. 

The decrease toward the outcrop in the thickness of the productive zone is . caused by two 

factors-the wedging out of the basal beds of 

the Etchego~ along the plane of unconformity and the replacement of the oil by tar 

in the upper part of the productive zone. · This. 

condition of affairs is well shown in the stereogram of sec. 36, T.31 S.,R.22 E. (Pl. XXXVII), 

and is discussed in the part of this report dealmg with the general mode of OCCW'rence of oil 

in the field (pp. 75-83). · 
104 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART L 

EXPLANATION OF PLATE XXXVII. 

The stereogram was constructed to show the structure 

and the interrelationship of oil, tar, and water-bearing 

beds in an area near tho outcrop of the B zone. This :figure 

is not a pe_rspective drawing and in consequence has a 

somewhat distorted appearance. It is, however, so drawn 

that the three reference lines are exactly to scale and on 

this account it can be used as a working drawing. The 

vertical scale of this block, however, is larger than the 

-scale in other directions, as explained below. The method 

of constructing. such a figure is briefly as fo1lows: 

A drawing of a block is constructed, as in :figure 9, which 

represents the block as seen from above, AD representing 

the width, DC the depth, and AE the height of the block, 

each dr~wn to scale. The rectangular face ADHE is represented as in the plane of. the paper and therefore is of true 

shape and size. The rectangular side DCGH of.the block, 

which in reality is at right angles to the plane of the paper, 

is shown diagonally, so that the right angle CDH of tho 

side of the. block appears in the drawing as 120°. The 

.E 

FlouR~ 9.-Diagram explaining method of constructing stereogram in 

Plate XXXVII. 

right angle ADO of the top_ of the ·block is similarly distorted in the draWing to 150°. Tho sides AB and AD are 

of the same length and are drawn on the same scale; the 

vertical dimension is made somewhat longer for convenience-in drawing but is drawn on the same scale. 

The intersection of the plane representing the surface 

of the ground with the sides of the reference block is 

sh.own iri :figure 10 by the lines IK, KL, LM, and MI. The 

part of the block below the plane representirig the surfac.a 

of the ground is considered as opaque, for it represents 

a block of the earth; the part of the block above the surface 

plane IKLM is considered as transparent, for it is simply a 

construction block. On the sides of the solid block the 

ductive oil sands (the B zone that is contoured on Pl. III) 

with the two front sides of the block is shown by the lines 

ST, TU. The outcrop of the upper surface of the sand is 

represented by the lineRS. 

In ·figure 11 the block is supposed t~ be separated along 

the. upper surface of the B' zone-that is, along the plane 

FIGURE io.-Diagram explaining method of con::tructlng stereogram in· 

Plate XXXVII. 

that is co11toured on the .map (Pl. III)-and the upper 

part of the block is supposed to be lifted so that the upper 

surface of the B zone is visible. On both the warped 

plane IKLM that represents the surface of the ground 

and the warped plane RSTUV that represents the upper 

f!urface of the· B zone contour lines arq drawn showing 

B Cc~/-_/r-----------::~7! .. R': 

s' 

edges of the strata that form the block are shown. The· FIGURE H.-Diagram explaining method of constructing stereogram in 

representation of these strata on the plane IMHE is _there- · Plate XXXVII. 

fqre a geologic cross section drawn true to scale, for that the elevation of these planes above sea level. These conplane is in the plane of, the paper. The repr~sentation tour lines correspond with part of those that are shown for 

of the intersection of the strata with the plane MLGH, the B zone on the map of the :field (Pl. III). 

however, is slightly distorted, for that plane which is in 1 In order to show the structure of the strata more clearly 

reality at right angles with that of the paper is shown I the vertical scale in the stereogram is made twice that of 

diagonally and all angles are distorted. The intersec- the horizontal scale, which makes the dip of the beds 

tion of the upper surface of the zone containing pro- steeper and thus distorts the structure somewliat. 
U. S. ClBOIJOOICAT, SUHVI~Y PROFESSIO~AL PAPER llo PLATE XXX\'U 

,--------------------------------~-------~ ,' I ,"' I ,~" I ,' I 

,'" : ,,."' : , I "' I ,"' I , I 

EXPI.t.ANATION 

-- 6 

Sand,clay, sha1e,and ~ravel. 

Showing attitude at"beds 

Beds containing oil Beds containing tar 'Beds containing water 

liori zontal scale 

oi:l-==:3::=======t====;i;;1'0~0;::0==========2::!:0:::JOO Feet· 

Vertical scale. 

STEHEOGllAM SHOWING STilUCTURE OF OIL SANDS IN SEC. 36, T. 31 S., R. 22 E. 
STATE-AMERICAN OILFIELDS AREA. 105 

'BEDS ABOVE THE B ZONE. 

The· B zone is· overlain directly by a zone 

averaging about 300 feet in thiclmess in which 

tar sands are abundant. I-Iere as in other areas 

that lie fair~y clo.se to the:outcrop, the separation between the oil and tar zones can not be 

0 1nade very definitely, on a8count of the 

irregular distribution of oil in the beds and 

also because of the lack of uniformity in the· 

ideas of the different drillers as to just what 

constitutea oil sand and what tar sand. Near 

the northeastern edge of the area tar sands 

'as a rule occui· abundantly l{p to a level within 

400 feet of the surface. 

DEDS. DELOW THE PRODUCTIVE ZONE. 

Some. 9 or 10 wells in this area have been 

drilled into the l\1aricopa shale, one of them 

pbnetrating it for 2,000 feet. Without exception, these wells have failed to encounter any 

considerable amount of oil, although 0 practically all have struck coarse lenses that contained some petroleum. . 

Tho Maricopa shale penetrated by .these 

the top of ·the B zone. Almost certainly the 

''stray" sand is flooded by this time. This 

water sand is the one that lies so close above 

the productive B zone near the center of sec. 36. 

Bqttom water.-The persistent bottom-water 

sand 1 that so closely underlies the C zone in 

the southeastern part of T. 31 S., R. 22 E. . ' contmues as far sou,thwest as the center of 

sec. 26 and the northwest corner of sec. 36. 

The approximate position· of the top of this 

water sand is shown on Plate XXXVI. Near 

the northwest corner of sec. 36 this water sand 

lies between 300 and 400 feet below the top of 

the productive zone. Water occurs also at 

approximately the same distance below the top 

of the producth:e zone in the center of sec. 36. 

The position of this bo.ttom water in the center 

of sec. 0 

36 is shown in the stereogram (Pl. 

XXXVII). Near the southeast end of the 

area water does not seem to underlie the pro-· 

ductive zone quite so closely. The Maricopa 

shale, however, contains numerous water 

sands, and drilling far below the base of the 

Etcl~egoin is not safe in any part of the area. 

wells is chiefly brown shale (probably diato- CHARACTER OF THE OIL. 

maceous shrule) with numerous "shells" and In the western part of the area the oil ranges 

s:mdy or even gravelly beds. Both the well from 13° to 19° Bal,lme. The gravity of the 

records and the outcrop~ higher in the foot- oil does not seem to bear any particular relation 

hi~ls indicate tha~ · the Maricopa shale i~ in to the distan.ce from the outcrop, for some of 

this area filled With sand:y le.nses ~hat oug~t the lightest oil is obtained in the wells that are 

to make excellent reservorrs m whiCh the . oil . closest to it, whereas wells near the northco~ld collect. The tests o.f the formatiOn eastern edge of the area and consequently 3,000 

which these wells have g1ven show that, to 4 000 feet from the outcrop yield heavy 

~lthoug~ o~ may o~cur in commercial amounts tan·; oil. 

1n certam Isolated lenses, th~se lenses are li?t ·1n the central part of the area the oil ranges 

numerous and that prospecting for them w1ll from 14o to 24o Baume· the averaae is abo t 

have to be done blindly and will be costly, .

2oo. ' ' 0 u 

for the percentage of dry holes will be very In the east end of the .area the oil is even 

largo. lighter, usually ranging between 22° and 24 ° 

WATER SANDS. · B l h h aume, a t oug certain wells, in general those 

Top water.-In the western part of the area that are troubled by water, yield heavy oil, 

northwest of the center of sec. 36 top water is some as heavy as 14 ° Baume. 

t·arcly ·found in wells drilled within 1,500 or In much of the area, particularly in the 

2,000 feet of the outcrop, practically the only western part, where water sand closely underwater i·eported being clearly surface drainage. lies the productive zone, the sands in the 

In the east ·end of the area, however, top wa.ter lower part of the productive zone contain a 

lies very close to the top of the B zone, prob- very heavy oil, in many places almost a tar. 

ably immediately above the top of the "stray" Many wells close to the outcrop have yielded 

oil sand that locally lies just above the B a rather larger amount of gas than is usually 

zone. In some of the wells in this area the obtained from wells so close to the outcrop, 

casing seems to have been set too low, and where the opportunity for the escape of the 

probably water from· this sand has entered . 1 See analysis 54, Table 24, Part II (Prof. Po.per 117). 

\ 

\ 

\_ 
106 ';['HE SUN,SET~MIDWAY OIL FIELD, CALIF.-PART I. 

lighter constituents of the gas _is relatively 

great. It seems, therefore, that the sealing 

of the beds must be rather more perfect here 

than .is· usual, and that the oil has suffered 

rather less than the ordinary amount of natural 

fractionation. · · 

PRODUCTION. 

This area has proved to be one of the richest 

in the Midway field, <!ertainly the richest that 

is s·o close to the outcrop. ·In the ·we~ tern 

part of the area many of the wells had an initial 

production of 200 to 600 barrels daily and a 

. "settled" production of 150 to 200 barrels. 

The.largest wells, however, are in the east ·end 

of the area, where several wells flowed many 

hundred barrels daily for several months. The 

. largest of these wells were American Oil:fields 

No. 79 and United No. 9 .. 

A remarkable feature of the production . of 

cerned with the proper handling of the wells 

already drilled. The chief troubles· here are 

abundant top water and some bottom water, 

which has been reached by several wells. In 

casing off the top water it will probably be nee-' 

essary to case off the stray oil sand also, for 

that has alreagy been done in many of the 

wells, and the sand must be by now pretty well 

flooded. In the southwestern part of the area 

the pr:oductive zone is not over 300 feet thick, 

and to drill more than 300 feet below the top 

of the zone is dangerous, for bottom water is 

abundant in the underlying Maricopa shale . 

MOCAL-HAWAIIAN AREA. 

[South edge of sec. 25; southeast corner of sec. 26; NE i, 

northeastern part of ·NW. !, and northeastern part of 

SE. t sec. 36, T. 31 S., R. 22 E.; southwest cornerof 

sec. 30; western par~ of NW. t and northeastern part of 

SW. t sec. 31, T. 31 S., R. 23 E.] 

.this area is the fact that there is no gradual LOCATION AND OPERATORS. 

decrease toward the outcrop in the productivity the The Mocal-Hawaiian area comprises of the wells. Up to 600 or 800 feet from the northern part of what may be termed the Feloutcrop the production of the wells is about 1 :fi ld t d' f th thi kl d ·n d . f h . h' f ows e , ex en 1ng rom e c y n e equal to the average o t ose Wit m 2,500 eet . d 26 th t first d · · . . area rn an near sec. a was eof the outcrop, but at a d1stance of 300 feet 1 · d b th St t C · lid t d 0 t 

h h d t.. ve ope y e a e onso a e o. eas - or so from t e outcrop t e san s are mucu d t · t b t th · t f ·1 

d · d h d nl war . o a porn a ou ree-quar ers o a nn e 

poorer and wells nile t ere pro uce o Y a th t f th t f F 11 (S . nor wes o e own o e ows. ee geo- few barrels of oil or are dry. 1 · t' PI' XVIII) Th · 

SUGGESTIONS FOR FUTURE WORK. 

In the western part of the area the productive zone is limited to a thickness of less 

·than 400 feet, arid within 1,000 feet of the outcrop 'it is less than 100 feet thick. Water is 

not present close below· the productive zone 

in the southern part of the are,a west of the 

center of sec. 36. Deep drillirig here is there-

.~or.e not particularly dangerous to _the productive sands, but it probably will not prove 

profitable, for although stray sands are to be 

expected in the upper part· of the Maricopa 

shale, such sands are not persistent and probably could not. materially increase the production. Bottom water is present near the 

northwest corner. of sec. 36 · and also both 

northwestward and southeastward from that 

point at approximately equal distances from 

the outcrop. Drilling in the part of the area 

lying northeast of this line should therefore 

not be continued below the base of the productive sands of the Etchegoin. 

In the northwest corner of sec. 6 the area 

is practically drilled up, ~nd future work is con~ 

ogiC sec IOns, • . · e compames operating here in 1916 were the Recovery, Visalia 

Midway, Chanslor-Canfield Midway Oil (sees. 

26, 31, and 3~), American Oilfields, Associated 

(Pioneer Midway), Honolulu Consolidated(Hawaiian), and ~ammoth. 

GEOLOGY. 

This area lies on the north flank of the Midway anticline, pretty well down the flank, 

where the dip is fairly l<;>w. On the north is 

the Twenty-six syncline, and ~n the east the 

Midway Valley syncline. Both of these synclines show their effect in the structure of this 

area, for the strike of the beds in the northern 

part of the area is somewhat more easterly than 

that of the beds in the eastern part of the area. 

The strike of the beds therefore makes a curve 

very gently convex toward the northeast, and 

the structure may be regarded as that of a very 

slight or broad anticline plU.nging steeply northeastward. This structure seems .to have had 

considerable influence in the concentration of 

the oil, however, for this part of the field has 

thus had an unusually large area from which 'to 

draw the oil now contained in it. Oil occurring 
. MOCAL-HAW AllAN AREA. 107 

in the basin of the Twe:qty-si.-x: syncline, to the 

north, would tend to move southward, and th~t 

formed in .the Midway Valley syncline would 

tend to move westward up the dip, to collect 

high on the flank of the Midway anticline. It 

is probable that a slight fold such as this would 

not have had so great an effect on the accumulation of oil were it farther from the outcrop, 

but here the sealing of the beds near the outcrop by asphalt and tarry oil has been nearly 

perfect, and the fold with this sealed end has 

been a better container for oil than the coarse 

lenses surrounded by impervious clays such as 

occm· throughout the section. It is noteworthy that this area and the area just to the 

west contain practically all the big wells in the 

Midway :fi~ld that al.·e close to the outcrop. 

OIL SANDS. 

to the outcrop than that at which the lower · 

sands in the same zone become dry~ Near the 

east line of the NE. 1 sec. 36 the oil sands in the 

C zone are separated· by ·barren clays almost 

equal in thickness to the barren measures 

lying between the upper sand of the B zone 

and the top of the C zone. These clays in the 

C zone are lenticular, how~ver, and can not be 

followed so definitely as the clay overlying that 

zone. 

In most of this area the productive zone may 

. be divided readily into the B and C zones, but 

near the southwest edge of the area these zones 

are not separable and together form a thick 

zone of oil sands with relatively little interstratified barren clay, shells, etc. · 

Along the south line of the NE; 1 sec. 36, 

the upper part of the productive zone is not 

recorded uniformly in the. logs of the wells. 

Practically all the oil obtained in this area Many of the logs do not record the upper part 

comes from sands near the base of the Etche- of the B zone, and, indeed, many of them do 

goin formatio.n, but one or two wells were not record anything as oil sand above the C 

ch·illed into the underlying Maricopa shale,· and zone. The top of the B zone, however, conin their logs oil sand is reported 300 to 400 feet tains oil here, and it should not be cased off 

below the base of the main productive zone. with the top-water sands. 

There is very little evidence as to the extent of Several of the big flowing wells near the centhese sands in the Maricopa shale, but they are ter of the east line of sec. 36 have obtained 

probably lenticular and will probably not prove their oil from a sand that lies ,at the base of the · 

very rich. . B zone-:-thatis, within 60 feet of the top of the 

Near the center of sec. 36 the total thick- 0 zon:e. This sand occupies approximately the 

ness of the combined B and C zones is about 400 same position as the sand that yielded the large 

feet, but toward the northeast the thickness flow of oil in Pioneer Midway well No. 2, about 

increases greatly, and near the northeast cor- a mile to the north, but in the intervening area 

ner of the section it is about 750 feet. Of this, no oil sand occurs at this horizon. It is evihowever, only about 250 feet is recorded ·as oil dent, therefore, that these sands are very lensand. This variation in thickness is evidently ticular, but their lenticularity is probably the 

caused by the unconformity at the base of the chief reason why the oil in them is originally 

Etchegoin and the wedging in of older beds under such high pressure. Near the center of 

toward the northeast. The angular discord- the east line of sec. 36 this sand has been 

ance in dip between. the Etchegoin and the recognized under an area ·of perhaps a square 

underlying Maricopa shale appears therefore to mile. 

be considerable and is apparently greater here In this same part of the area a stray sand 

than in the other areas occupying a similar about 10 feet thick is reported in one well 

position along the foothills of the main ridge. about 60 feet above the top of the B zone. 

The upp~rmost part of the B zone contains a This sand yielded heavy oil for a short time at 

remarkably persistent oil sand which has been a rate of about 80 or 90 barrels a day, but it 

recognized as far toward the northeast as the was a:eparently soon exhausted and has not 

SW. 1 sec. 30, T. 31 S., R. 23 E. Near the been recognized in the neighboring wells. 

northeast corner of sec. 36 it is about 20 feet 

thick and is separated from the underlying C 

zone by some 200.feet of barren strata. It is 

rather remarkable that this sand should be so 

persistent, for usually the upper part of the B 

zone becomes nonproductive at a point closer 

BEDS ABOVE 'l.'JlE B ZONE. 

· In the southwestern part of the area tar 

sands are scattered through the beds from a 

point betiveen 600 and 800 feet below the surface ·down to the top of the B zone. In the 
108 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

northeastern part of the area tar sands are encountered at about an equal distance below 

the surface and also close to the top of the B 

zone, but in the intervening strata they are not 

abundant. The uppe:r tar sand here. is usually 

between 200 and 400 feet thick. The lack of 

tar in the beds fair~y close to the top of the 

productive sand in the part of the area where 

the sand lies deeper is probably more apparent 

than real, for many of these wells are drilled 

with rotary tools and. no attention. is paid to 

character of the beds so far above the pay 

sands. Ho~ever, the regularity with which 

the upper tar sand is recorded suggests that 

it is especially heavy. 

WATER SANDS. 

of the area, all in sec. 36-near the center, 

near the northwest corner, and near the 

center of the north line of the section. The 

water found near the center and near the northwest corner occurs either in the basal bed of the 

Etchegoin formation or in the 11aricopa shale. 

The Etchegoin rests with marked unconformity 

upon the ]\1aricopa shale, and along. a belt that 

extends in a northwesterly direction through 

the center of sec. 36 the Etchegoin appears to be 

thinned considerably, probably because along 

this belt the· Maricopa shale, upon which it 

rests, is somewhat higher than normal. The 

explanation of the occurrence of water here 

that best fits the known facts seems to be that a 

water sand in the. Maricopa shale reaches the 

plane of unconformity along this belt and that 

Top water._:_ Throughout the area the B zone water from it lias entered the basal bed of the 

is closely overlain by water sands, and in most Etchegoin and flooded that bed along a belt 

.of it the water string should be set very close that probably extends from a point north of 

w. · the northwest corner -of sec. 36 ~early 

SEC.36 L if not quite to the southeast corner of 

~-------...;._-~~:......,. _____ ~s~E~c._:32~ the section. This belt is narrow, however, and does not extend to the northeast down the dip. The sands now 

occupied by water lie 200 or 300 feet. 

below the top of the productive zone 

and apparently are not. separated by 

much barren clay from the base of that 

z~me. Care must be exercised here in 

order to avoid drilling too deep. In 

those parts of the area where water 

Water sands 

~-------ApprOJ<J.'mstely!¥mi/~.s -------~ 

FIGURE 12.-Diagram showing relation of water sands in sec. 32, T. 31 s., R. 23 E., occurs very close below the productive to those in the northeastern· par~ of sec. 36, T. 31 S., R. 23 E. 

to the top of the :a zone. The exact position 

of these top-water sands is not known, for they 

are reported as scattered through the beds that 

lie between 200 a:r;td 300 feet above the B· zone. 

· Near the center of the north line of sec. 36 top 

water has been especially troublesom'e and 

seems to be. separated from the B zone by only 

a very few. feet of clay. In the northeast 

corner of the area water is present in the uppermost part of the B zone. The position of these 

sands is shown in the geologic section (Pl. 

XVIII, B). However, except ip. this extreme 

northeast corner of the area and in the vicinity 

of the center ofthe north line of sec. 36; where 

the water sand so closely overlies the B zone, 

top water should not be troublesome, for there 

appears to be sufficient clay beneath it in which 

to shut it off: · 

zone, the lowest oil sands contain 

heavier oil than those in the upper part of the 

zone, and the presence of su9h oil will serve as 

a warning to stop drilling. 

Near the east line of the NE. t · sec: 36 the 

deep wells that have been drilled 500 feet or 

more below the top ·of the C zone have not certainly encountered water. One well may have 

encountered bottom water, but the record is 

not· en.tirely satisfactory. Although the 'Y~lls 

in this area do not find any water in the C zone, 

water is present in both the upper and lower 

parts of' that zone only a short distance to the 

east, and it is probable that as oil is extracted 

from the ·sands near the east line of sec. 36 

water will work westward into the parts of the 

sand that now contain oil. The gen~ral conditions here are shown in figure 12 and Plate 

XVIII, B . 

. Bottom. wa.ter.-:-Bottom water has ·been The persistent water sand· that immediately 

encountered by SOUle of the wells in three parts underlies the gusher sand of sec. 32; T. 31 s., 

\ 
MOCAL-HAW AllAN AREA. 109 

R. 23 E., is probably the sand most to be 

feared .. In sec. 32 it lies within 100 feet· of 

· the top of the C zone. 

In the northern part of the area the C zone 

is closely underlain by the persistent water 

sand that extends over so much .of the southeastern part ofT. 31 S., R. -23 E. The approxi-

:mate position of the top of this sand is shown 

on the sketch map (Pl. L~~VI). 

In several parts of the area more or less 

water has been encountered, but it does not 

appear to come everywhere from the same 

sand. The chief water trouble in the northern 

part is clearly from top water. ·Near the 

center of sec. 36 the <?hief trouble is probably 

fr01n bottom water, although top . water may 

have contributed. Near the northwest corner 

of sec. 36 any water so far obtained probably 

came from a bed below the C zone, but with 

exhaustion . of oil edge water in the C zone 

will probably appear. 

CHARACTER OF THE OIL. 

The oil in this area is fairly uniform in 

gravity where wa.ter is not troublesome, 

ranging from ab0ut 20° to 25° Baume. Where 

water is troublesome the oil seems to run 17° 

to 19° Baume·. The oil does not appea.r to 

get hea:vier regularly toward the outcrop, but 

there is a very distinct difference iri gravity 

between the oil from the B zone and that from 

the C zone in the northeastern pa.rt of the area. 

The upper sand is said to furnish oil of about 

17° Baume, whereas the oil from the lower 

zone, or perhaps a m:Lxture from both upper 

and lower zones, runs 20° to 25° Baume. 

PRODUCTION. 

In this area are many of the largest wells 

of the Fellows field-wells that were originally 

spectacular gushers. The biggest wells here 

were I-Ionolulu Nos. 1, 10, and 12; American 

Oil'fields Nos. 34 and 56; and Mammoth No. 

2. Visalia Midway No. 2 was al~o a flowing 

welL for two years but did not flow wild. 

Most., of the wells except those along the 

extreme southwest edge of the a.rea have had 

~ settled production of over 100 ba.rrels daily, 

some of them 200 to 300 barrels. With a few 

exceptions the wells produced 60 barrels or 

1nore da.ily in 1914. 

FUTURE DEVELOPMENT. 

It is practically certain that further exceptionally large flowing wells can not be expected in this area, but much of the area gives 

promise of wells with a settled production of 

100 barrels or more daily. This· is particularly t111e of the northeastern part of the areathat is, the part in which the oll-bea.ring 

:;>trata lie deeper .. It. is probable that the southwestern edge, particularly· near the center of 

sec. 36, will yield a much smaller production. 

The uppermost part of the productive zone 

near the south line of the NE. i •sec. 36 is not 

properly tested.by many of the wells, although 

top water does .not seem· to be especially dangerous here, and the upper sands could probably be tested without danger to the productive 

sands. The oil in these sands, however, is· 

hea\-rier th~n that furnished by the low·er sands. 

In the northeastern part of the area the upper 

sand becomes much thinner and contains heavy 

oil, of about 17° Baume. It is probable that 

edge water now occupies. part of this sand and 

that any new wells near the northeast corner 

of sec. 36 will find it profitable to cas~ off this 

sand and produce only. from the lower ones. 

This statement may apply also to wells drilled· 

as far southwest as a line drawn· from· the 

\ricinity of the American Oilfields No. 5 to 

Mam..illoth No. 2. 

Drillers of wells in the vicinity of the center 

of the north line of sec. 36 should use exceptional care m shutting off top water-, as it 

seems to be very close to the top of the pro- , 

ductive zone. It may be that the upper part 

of the productive .zone should be cased off here, 

as this has already been done in some of the 

wells, and it is possible that the upper part of 

the producltive sand is now flooded. 

Bottom water appears to lie fairly close to · 

the productive zone in the center. of sec. 36. 

As suggested befDre, it may be that in this vic·inity the presence of heavy oil will give an· 

indication of th~ proximity of bottom water. 

.In the n.ortheast comer of sec. 36 bottom water 

apparently lies ·close below the productive 

zone, but here that zone seems to be fully 700 

feet thick-that is, the lowest productive sand 

lies a little more than 500 feet below the 

sand that forms the uppermo~t part of the C 

zone, which is really the chief producing sand 

here. Somewhat farther east the individual 

oil sands making up the C zone ~e separated 

by water sands, and here also the chief oil 

sand lies at the very top of the C zone. As the 

oil is exhausted water will work its way up the 

dip and appear in thewells near the northeast 
11.0 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

corner of sec. 36. The chief water which is to 

be feared is that. which lies immediately below 

the upper oil sand in sec. 32-that is, the sand 

which forn1s the uppermost part of ~he C zone. 

.(See the description of that area, p. 112, and 

geologic section, Pl: XXI.) 

low arch or saddle that separates the Globe 

anticline from the United anticline. 

The dip of the beds is low throughout the 

area, rarely being over 6° or 7° along the extreme southwestern edge. The strike is regularly northwestward, except of course along 

the axial part of the fold of the Midway Valley 

PIONEER MIDWAY-MIDWAY CONSOLIDATED syncline, where the beds start to swing about 

. AREA. the axis of the plunging fold. This syncline 

[Southwestern part of sec. 29; southeastern part of sec. 30; 

.NE. !, northeastern part of NW. f, and north~astern 

part of SE. t sec. 31; sec. 32; and SW. t sec. 33, T. 31 8., 

R. 23 E.; northwest corner of sec. 3; northwestern 

part of sec. 4; and northeastern part of sec. 5, T. 32 8., 

R. 23 E.] 

LOCATION AND OPERATORS. 

The Pioneer Midway-Midway .Consolidated 

area includes the eastern part of the Fellows 

field,' forming a belt about 1 or 1 i miles wide 

. that extends from a. point approximately 1! 

miles due north of the town of Fellows southeastward,· parallel to Midway Valley, to a 

. point about 1! miles east of the town. It lies 

entirely on the flat, extending from the edge of 

the foothills of the Temblor Range to the cen:-

ter of Midway Valley. (See geologic sections, 

Pls. XIX-XXI.) The companies operating 

here in 1916 were the Kern Tradirig & Oil, Associated, Consolidated Mutual, Honolulu (Hawaiian), Columbus. Midway, California Midway, 

. Buick, Olig Crude, General Petroleum (Fellows 32), Pacific Crude, Alaska Pioneer, Chanslor-Can:field Midway Oil, Mammoth, Eagle 

Creek, Canadian Pacific, Midway Consolidated, 

Wilkes-Head, Vancouver Midway,. California 

Counties, and Standard (Equitable). 

GEOLOGY •. 

plunges .southeastward, but, except possibly 

in the extreme northwestern edge of the area,· 

the piunge is not m~re than 1° or 2°. At the 

extreme. northwest corner of the area, where 

the Midway Valley syncline forks, . the beds 

show a very slight tendency to aline themselves with the tren'd of the Twenty-six syncline. 

. The Midway Valley syncline appears to be a 

rather flat-bottomed trough, the lowest part 

of which forms a zone that extends for about a 

mile toward the southwest from the axis of the 

fold. In much of· the area the dip increases 

rather abruptly along a line trending parallel 

to the axis of the sy:p.cline and lying approximately ·a mi;J.e or a mile and a quarter southwest of it. This line may be considered to 

separate the synclinal portion of the field from 

the portion that i~ more closely allied with the 

Midway and other small anticlines along the 

flank of the Temblor Range ap.ticline .. In the 

part of the area north of the t~wnship line 

separating Tps.' 31 and 32 S. no such sharp 

division may be noted, for the dip increases 

gradually from the synclinal part of the field 

toward the axis of the Midway anticline; but 

in sees. 5 and 8, T. 32 S., R. 23 E., the separation is well marked. The line ·along which the 

dip changes abruptly trends southeastward Mo~t 'of this. area lies f~irly well out toward from the northeast corner of sec. 6 to th~ center 

the axis of the Midway Valley syncline, where of sec. 5 and.thence to the center of the south 

the Tertiary beds are hidden., under a .cover of line of sec. 4. 'This difference in the degree to 

·alluvium, which is thin near the foothills but which the beds are tilted, although slight, 

which is probably a few hundred feet thick in seems to have had a marked effect upon the 

the central part of Midway Valley. The accumulation of oil, for in the northern a~eanorth end of the area lies near the point where that is, the area of low dip-the upper part of 

the Midway Valley syncline ceas~s to form a the zone that is productive in the foothills, 

single trough and frays out into two minor where the structure is dominated by the Midfolds, one of which, the Twenty-six syncline, way anticline, contains oil closer to the axial 

extends northwestward through T. 31 S., R. 22 part of the syncline than it does in the southern 

E., and the other:, the larger one, northward area, where the dip is higher and the change in 

through sec." 19, T. 31 S., R. 23 E. This main attitude is more abrupt. In this southern 

branch of ~he Midway syncline may terminate part of the area, where the dip is high and then 

in the eastern portiqn of sec. 19, but even if it changes abruptly to form the floor of the syndoes, its effect is shown by the presence of the ,·cline, the upper part of .the zone that is pro-
PIONEER MIDWAY-MIDWAY CONSOLIDATED AREA. Ill 

ductive near the axial part of the Midway anticline remains productive approximately to the 

·line along which the dip changes, but east of 

that line it is almost if not quite barren of oil 

and usually contains water. Between this 

line and the axis of the Midway valley syncline 

the productive sOJlds are limited to the lower 

part of the zone that is productive close to the 

. axis of the Midway anticline. 

OIL SANDS. 

The oil snnds in this area are entirely in. the 

Etchegoin formation, for marine fossils are 

reported both in the ·deepest sands yet encountered and in beds which over~ie the upperInost productive sands. No well here has yet 

been drilled deep enough to penetrate all the 

Etc.hegoin and enter the Mar~copa shale. To 

·judge frmn the results of the deep wells drilled 

farther west th~ Maricopa shale would probably not prove productive in tlris area. · 

The productive sands here lie chiefly in the 

C zone, but the B zone contains oil in places 

along the southwestern edge of the area, particularly near the northeast corner of sec. 5. 

The general character of the productive zone 

in the~ different parts of the area may be summarized about as follows: 

In a narrow belt along the southwestern 

margin of the area the B zone contains oil in 

sMdy lenses that have a somewhat irregular 

extent. In this same part of the area the C 

zone is probably. about 500 feet thick. The 

best oil sands lie near the top of the C zone, 

but less rich sands are scattered through the 

zone from top to bottom. No water occurs 

within the C zone here. 

In the eastern part of the area the total 

thiclmess of the C zone is probably a little. 

· greater than it is near the southwestern margin, but here the chief oil sand is thin and lies 

at the very top of the p zone, and water sands 

are abundant in the zone, separating various 

sands reported ·to ~011-tainoil. 

The B zone is usually 150 to 200 feet thick 

and is productive about as f~r north as the 

center of the east line of sec. 31, beyond which 

it is occupied by water. As is usual along the 

outer edge of the ''transition belt," the oil 

sands in this zone are irregular and may only 

with difficulty and uncertainty be correlated 

between wells. No persistent oil sand' comparable with that which occurs at the top of 

the B zone near ~he northeast co:rner of sec. 

36 has been found here. 

In the area just northwest of that here described, near the east line of the NE. ! sec. 

36, T. 31 S., R. 22 E., the C zone is composed 

of in terstra tified oil sands and barren strata 

that have a total thickness of about 500 feet, 

and of this zone about half is usually recorded 

as oil sand. Eastward for. half a mile or so 

from this area the oil in the C zone is restricted 

more and more to a few thin sands that are 

separated from one another by barren clays. 

Farther east the oil sands are still thinner, and 

water sands appear in the barren 'clays that 

separate the oil sands. The conditions existing. here are shown in figure 12. 

The oharaoter of the productive zone is best. 

lmown in sec. 32, for here the upper part has 

been pretty thoroughly drilled. Its character 

is shown graphically in the geologic sections 

(Pis. XIX-XXI). The chief features of the 

productive zone here are described below: 

The upper part, usually 20 to 30 feet thick, 

is oil sand· (the ohief producing sand in this 

section), below which is about an equal thickness of clay; then a water sand 10 to 20 feet 

thick containing .salt water (the troublesome 

bottom water encountered in so many of the 

wells). Lying between 270 and 330 feet below · this water sand is another sand said to 

.yield flowing water. Between these two water 

sands various oil sands are reported, but these 

have not" been thoroughly tested, and their 

position is not accurately known. The lowest 

water sand reported is probably not over 50 

feet thick and may be only 10 feet thick. Beneath it· oil has been reported, but the extent 

or productivity of this sand is not known. __ 

The sand forming the uppermost part of 

this zone is the one that has yielded the largest 

production, and almost all the wells ill seo. 32 

penetrate only this upper sand. Its thickness 

as reported in the record of wells in the eastern 

part of sec. 32 ranges from 10 to 30 feet. There 

appears to be very little :r:egularity in the 

variation.~ thickness reported for this sand, 

and the difference is evidently more a personal factor dependent on the driller than a 

natural depe~dent on the position of the sand. 

For a distance of 200 to 300 feet above the 

top of this sand-that is, in the. beds that are 

equivalent to the B zone of the western part 

of the area-traces of oil 'and gas occur, and 
112 THE SUNSET...:MIDWAY OIL FIELD, CALIF.-PART _I. 

showings of gas are repor,ted. still higher. 

These showings, .however,· evidently do not 

indicate deposits of commercial value, and the 

water st_ring may safely be set in a short dis.:. 

tance above the top of the C zone. 

BEDS ABOVE THE PRODUCTIVE ZONE. 

So many of the wells in this area have· been 

drilled by rotary. tools that any general statements regarding the character of the beds 

above the productive zone are not. very reliable. It seems, however, that here as elsewhere in the field the uppermost tar zone is 

encountered at a depth of less than 1,000 feet 

below the surface, showing again that either 

this thickness of strata is insufficient to prevent the fractionation of the oil and the total 

loss of the light constituents, thus resulting in 

the deposition of the tar, or else the highly 

.sulphate surface waters are encountered at 

about this depth, with the consequent oxidation of the hydrocarbons and the addition 9f 

· .sulphur. The probable relation of surface 

waters and the upper tar zone is shown by the 

fa~t that practically all the wells that record 

top water record.it either in or just below this 

tar zone. Usually below this water, or below 

· this combined tar and water zone, no more 

, water or tar 'are recorded until the position of 

the B zone is approached. 

WATER SANDS. 

The position of several of the water sands 

has already been d~scribed in the section describing the. oil sands. Top wa t~rs are seattered ·through the beds from the surface of 

the ground down to the top of the· B zone; 

edge water occurs in the B zone; and water 

sands are interstrati:fied with the oil sands of 

the C zone in the eastern part of sec. 32. 

Top ~ater.-T~e water in the sands that lie 

above the top of the B zone is, for the most part, 

not under heavy pressure and is cased off by 

the water string, which in the western part of 

the area is set above the top of the B zone, or 

in the parts of the field where the sands lie 

deeper, above the top of the C zone. Probably 

the most regular of these water sands is the 

· one which lies at the base of the tar zone, 

encountered a·t a depth of less than 1,000 feet 

below the surface. 

Edge water in B zone.-The B zone contains 

oil only in the southwestern part of the area, 

chiefly near the southwest corner of. sec. 32. 

Northeast of this ·point the upper part of the 

B zone is occupied chiefly by water.1 Many 

of the wells in sec. 32 do not record top water 

within 300 or 400 feet above the oil sand, but 

the other wells show that in the northeastern 

part of the section there is a persistent water 

sand that lies between 230 and. 300 feet above 

the C zone. This water sand is probably in the 

B zone, and the water is thus true edge water 

for that zone. The logs of a few of the wells 

in sec. 32 record a lower water sand which lies 

only about 100 to 125.feet above the top of the 

C z~:me. This water sand may be thesame as 

the ~ater sand noted a similar distance above 

the 0-zone in the northwest' corner of the section. In. any case, in the NE. l sec. 32 it is 

safest to set the water string somewhat less 

than 100 feet above the top of the C zone .. 

In sec. 4, except in the northeast corner, top 

water appears to be farther above the C zone 

than in sec. 32, but the records of it here are not 

very reliable. A sand yielding a heavy flow· of 

water is recorded as lying about 300 feet ·above 

the top of the C zone, but other water sands 

are recorded, one of them lying only 15 feet 

above the top of the C zone. In the southwestern portion of sec. 4 water occupies the 

upper part~ though not necessarily the uppermost part, of the B zone, occurring between 17 5 

and 227 feet above the top of the C zone in the 

three wells whose logs record top water. 

Water in the 0 zone.-The water sand that 

has given the most trouble in this area is the 

one that lies immediately below the oil sand 

which has yielded the chief production in sec. 

32-that is, the thin oil sand at tb,e very top 

of the C zone. The water from this sand is 

commonly termed bottom water. This water 

sand lies between 35 and 85 feet below the top 

of the C zone, the average bemg about 50 feet. 

Inasmuch as the oil sand at the top of the C 

zone is reported to be between 10 and 50 feet 

thick there, it has been difficult to penetrate 

the oil sand without also penetrating the underlying water sand. . 

The water sand that lies about 300 feet below 

the top \of the C zohe ill sec. 32. has been penetrated by only. one or two wells, and as no 

productive oil sands lie close to this sand water 

from it has probably not yet been a source of 

danger to· the Qil sands. The position of both 

the above-described water sands in the C zone 

is shown on the geologic sections (Pis. XIXXXI). 

1 See analysis 44, Table 22, Part U (Prof. Paper 117). 
PIONEER MIDWAY-MIDWAY CONSOLIDATED AREA. 113 

OHARAOTER OF THE OIL. 

The oil produced in this area in 1914 ranged 

in gravity from ·about 22° to possibly 28° 

Baume, the average being about 25°. Very· 

little of the oil is lighter than 26.5° Baume. 

The gravity of the oil produced by· t~e first 

wells drilled here was 1° to 2° Ba~e lighter 

than oil produced by the same wells in 1914. 

This decrease (increase in specific gravity) was 

shown most notably by the pig flowing wells 

that were first drilled in the section. 

There is a distinct difference in gravity 

between the oil in the upper part of the productive zone and that in the lower part. The 

B zone, which forms the upper part of the 

productive zone in a narrow strip along the 

southwestern edge of the area in· sec. 31, 

furnishes oii of 17° to 20° Baume. A mixture 

of this oil with oil from the C zone ranges from 

20° to 23°. · Wells that have had water trouble· 

or are near wells that have had such trouble 

yield heavier oil. 

PRODUCTION. 

part of the C . zone has yielded the ·oil so far 

produce~. The productive sand is thin and 

apparently decreases in thickness from the 

southwest toward 'the. northeast-that is, as it 

~pproaches the axis of the syncline. This thin 

sand has contained· oil under tremendous 

pressureandhasyielded bigflowsof oilwhen:first 

tapped by the drill. The initial production of 

wells which may in the future be drilled into 

this sand, even at some distance from present 

wells, will evidently not be nearly so great as 

that of the first w~lls, for the gas pressure has 

been very greatly r~duced throughout the area. 

Thin sand~ such as this can not be expected to 

yield wells' that will be very long-lived, and the 

great decrease in productivity shown by the 

wells which have been drilled is quite what is 

to be expected. · 

The water sand underlying the producti~e 

sand that forms the upper part of the C zone 

in the eastern part of the area occurs so close 

to the oil sand that it has very n~turally been 

drilled into, and much of the oil sand is now 

flooded with water and doubtless ruined. . 

This area . contains a number of wells that This part of the area shows some promise of 

, have had a very high initial production, several yielding oil from sands which lie· below· the 

of them as much as 10,000 barrels or more daily. watersand just mentioned. Such oil sands as 

The settled production of many of the wells those recorded between the· two water sands 

has been more than 1,000 barrels daily for. encountered in the wells 'that have been drilled 

periods of several months. These big wells are· in sec. 32 may yield considerable oil, as may also 

not grouped in any particular part of the area the still deeper sand recorded below. the seeond 

but are scattered through it from the riorth end "bottom 'water." · It seems as if the conditions 

nearly ·to the southeast corner of sec. 32. here ·ill a measure duplicate those that occur 

The whole area is, however, "spotted," and in ·Maricopa Flat (sec. 32, T. 12 N., R. 23 W.) 

between the big wells are many wells which -that is, that ~ere there are a number of interhave never produced more· than 100 barrels fingering oil ·and· water sands. The ·exact 

a day. The smallness in' yield of these wells position of either the water or the oil sands can 

may of course be due in part tu faulty drilling be determined only by drilling, but testing for 

or more probably faulty methods of bringing these sands is well worth while. This area is 

the well in, but the lenticular character of the not, however, nearly so favorable as Maricopa 

beds is probably the chief ~ause of the ·variation Flat, as there is here no well-deYeloped antiin size of the wells. clinal fold along which the oil would tend to · 

Mter the frrst big flow the output ~fthe wells collect. · . 

has decreased rather rapidly, and in 1914·most Testing for lower sand should be carried on 

of them were making less than 100 barrels and with due care for the protection of the upper 

probably less than half a dozen in the whole sands. Thus in testing for the deepest sand 

area made more than 200 barrels daily. · said. to have been encountered it would be 

FUTURE DEVELOPMENT. necessary· to set the following casings: (\) The 

water string above the top of the C zone (corSo far as sec. 32 is concerned (and probably· responding with the water string set in the 

much of this 'discussion will apply equally well wells now drilled); (2) the string below the top 

to the southwestern part of sec. 33 and the oil sand of the C zone, to protect that sand 

northeastern p~t. of sec. 4), the uppermost from "bottom ·water;" (3) a string below the 

109288~--19----8 
114 THE SUNSET~MIDWAY OIL FIELD, CALIF.-,-PART I. 

"bottom water'' which lies ]ust ·below this GEOLOGY. 

upper oil sand, to enable the sands that oc?ur · This area lies on the north flank of the 

between this water and the lowest water ·to be Midway anticl4le, .near the place where that 

tested; ( 4) if these sands are produc~ive another fold plunges southeastward. The beds dip 

string between them and the· top of the second northeastward, usually at angles between 10° 

"bottom water" sand; and (5) a string below and 15°, but nowhere within this area do they 

this second water sand, to enable the deep sand show a· tendency to· bend around the end of 

underlying it to be tested. the Midway anticline, the strike remaip.ing 

Probably ~one of the wells that have been approximately southeast to the southern edge. 

drilled in sec. 32 for a considerable distance ·of the area. 

below the top of the C zone have given. the Besides the Midway anticline there is probbeds at lower horizons an adequate test. All ably another fold in this area which has. had 

of them ·have been troubled With bottom water, some effect upon the accumulation of oil. 

both the water ·which immediately underlies This fold is indicated by a slight topographic. 

the upper. member of the C zone and the rise near the eastern edge of sec. 6, passing 

water which occurs some 250 feet lower. about through the ·Chanslor-Can.field Midway 

In· considering the possible value of the Oil Co.'s well No. 3. The dip of the beds can 

lower sands in this area the character of the not be made out from the surface exposures, 

lower sands in the ~rea just to the west should and the fold can only be inferred from the 

be considered. In that area several wells have topogr·aphic evidence. 

been drilled 300 feet· or more below the .top The angular discordance in dip. between the 

of the C zone. Although many of ~hem derive Etchegoin formation and the underlying Marisome oil from the lower sands encountered, copa shale.is considerable, and in consequen9e 

the· best production in most of them is re- · the lower part of the zone that is productive 

corded as coming from the upper part of .the in the northeastern part of the area is wedged 

C zone. Thus, although one would naturally out abruptly toward the southwest. 

expect the basal beds of the Etchegoin for~ation to be the .most productive, it is entirely OIL SANDS. 

possible that bottom water has forced the oil The chief oil-bearip.g sands here, the B and 

out froin the lowest beds ·of that formation C zones, are in the basal portion of the McKit-

. and that the oil has acc~mulated only in. the trick group. The san.d described as the A zone 

ver.y persistent .coarse .bed which pccurs some (which corresponds to the upper part of the 

distance above· the: base of the formation in zone described as zone B by Arnold and Johnthe axial part of the· syncline. It appears, son 1 ) may be in the Pas~ Robles formation, 

however, to be .well ·worth while to make .a. for no ·fossils have been .found in it. This 

~areful test· of these lower. sands~ sec. 32. ' sand, however, does not· form an important 

... part of the productive zone ·in the _area deMAMMOTH-ST. LAWRENCE AREA. . scribed, being :r;>rodtictive only in t~!3 extreme 

[Southwestern part of sec. 31, except the extreme south· southwest ·corner of sec. 5 and possibly in a 

west corner,·T. 31 s., R. 23 E.; northeastern part. of part of the ;E. t sec. 6. Oil has been found 

sec. 6; southwestern part of NW. i, W. ! SE. i, and also in some of the deep wells that have pene-. 

SW. i sec. 5, T. 32 S., R. 23 E.] d h. t' f th M · h 1 . trate t e upper par o · e ar1copa s ~e. 

LOCATION AND OPERATORS. The productive .. oil- sands :rpay be grouped 

The Mammoth-St~ Lawrence area embraces into three divisions, the A, B, and C z0nes. 

the ·southern part of the :~fellows field, extend-· .'The three zones· are not productive throughout 

ing from a· point about half a . mile north of· the area nor is it possible in all parts of the area 

the town of Fellows·southeastward to a point to recognize a line ~f separation· between some 

within half a rllile of the old Chanslor-Canfield one of these and the overlying or underlying 

Midway Oil ca:qtp ·in sec·. 8. (See geologic zo'ne, for to the west the three zones merge. 

section, Pl. XXII.). The companies operating The general steplike arrangement of the prohere ·in 1916 were. the Chanslor-Canfield Mid-. ductive oil sands is sho_wn diagrammatically in 

way Oil, Kern Trading & Oil, Midway Premier, figure 13. 

Midway Five, Kalispell, St. Lawrence, Hale -~ A-m-o-Id-,-R..:..al-ph-,-'-a-nd-Jo-hru-s-on-, -H-. R-.-, u-.-8-. -Gc_o_l._.s_ur-ve_y_B_tJ_I_. 4-06, 

McLeod, Eagle Creek, and Mammoth. p. 144, pl. a, 19io. • 
MAMMOTH-ST. LAWRENCE' AREA. 115 

Along th~ southwest~rn ~argin 0~ the area r BEDS AhOVE ·THE. B ZONE. 

the productive sands With l.I)terstratdied clays 

form h, zone that averages about 400 feet in In most of the area, certainly in the souththiclmess, which can not here be divided into western part arid probably as far northeast as a 

. any definite parts. Toward the northeast, lin~ drawn ~rom .northwest. ~o so~theast however, the productive zone· thickens some- throug~ the cent.er of sec. ~' It IS poss1~le ~o 

what, reaching a maximum of 600 or perhaps· recogni~e a~proXIIDat~ly the A zone, W~ICh. 1~ 

700 feet, and in the southern part of the area, pro~u.ctiv.e ·1n the axial part o~ the Midway · 

northeast of aline drawn between the Chans- ·anticline m sec. 8. · Th,e A zone 1s not produclor-Canfield Midway Oil Co.'s well No. 17, in tive in this area but is represented by a tar 

sec. 6, and St. Lawrence No~ 3, in sec. 5, the zone-frequently recorded .as "oil sand" or 

productive sands may be grouped fairly defi- ''heavy oil sand "-'-which has a· thickness of 

nite~y into the B and C zones. In this part about 100 or 150 feet. The top of this tar zone 

of. the area. the B zone is .approximately 200 lies 400 to 500 feet above the top of the B zone. 

feet thick. It has yielded oil in most of the Water occurs both in· this tar zoJ;ie and in the 

area, but near the northeastern edge the oil beds between it and the top. of the B zone, in 

sands in it become very thin, rarely being most of the area outside of that in which the A 

over 60 or 70 feet and in places only 10 .or 20 zone is contolired. (See map, Pl. III.) 

feet thick, and the uppermost >-"' 

Part of the z'one 'is occupied ~~ ~:g 

by·w'ater. · sw. ~Ill 

In the northern part of the ~~~~~~~~ area, near the center of theW.! 

Midway 

Valley 

NE. 

Approximate scale 

sec. 31, the uppermost 1.0 to 

30 feet of the B zone contains 

heavy oil, and from this sand 

a few wells have obtained oil 

for a short time. This sand is 

evidently the equivalent of the 

persistent sand at the top of the 

B zone near the northwest corner of sec. 3Q. It does not 

everywhere contain oil, how- FIGURE 13.-Diagram showing rel~tions of productive oil zones.in the vicinity of Fclfows •. 

ever, but in places contains gas under consider-~ Besides the· tar sands in the A zone,· tar 

. able pressure. Below this sand are barren beds sands are recorded up to levels within 600 or 

approxim~tely 100 feet in thickness, beneath 800 feet of the surface. The uppermost tar 

·which is a rather irregular oil sand that is sand recorded in this area lies·· ·somewhat 

~ec?gnize~ only in about half o~ the wells. deeper than the . uppermost. tar sand in· the 

flus sand IS about 70 to 100 feet thiCk and rests area between Fellows and- the'· axis of'· the 

directly upon. the C zm~(;), fo~ming, wit~' that Twenty-six syncline, where the productive oil 

zone, a corttmuous pro4uctr~e zo~e . ~n the sands lie deeper than they do here. It seems 

center of theW. t sec. 3.1. .It IS from this sand strange that there should be this difference in 

that t~e gusher prod~ctlqn ~one or two. of the the relative position ·of the oil ·and tar sands 

wells JUSt north of this locahty was obtamed. · th t f ld t th 

The C zone varies greatly in thickness on . mt. . e dwot arbeas, or one wou l expec t et . . ar san o ear a more or ess cons an 

account of the unconformity at the base of the 1 t' t th il d' · d h ·

1

. d . re a 10n o e o .san an t us to Ie eeper Etcheg01n. Near the southwestern edge of ~he h. h .1 d 1

. d . · . area the lower 200 feet or so of the productive w ere t e 01 san Ies eeper beneath the 

zone is probably to be correlated with the C surface. 

zone. Near the center of sec. 5 the C zone is BEDS· BELOW THE o 7.0NE. 

about 250 feet thick and its top lies about 300 

feet below the top of the B zone. The _variation in thickness is shown in the geologic sec-

. tion (Pl. L~II). 

A considerable number of wells, bo'th in this 

area and in sec. 8, ju:st to the south, have been 

drilled deep and have entered the Maricopa 

shale. Most of· the :deep wells in sec. 8 and 
116 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

many of those in this area have encountered the zone that edge water will probably first. 

bottom water, but a few have found lenses appear in the area now under consideration as 

·containing considerable oil. the oil becomes exhausted. 

WATER SANDS.· CHARACTER OF' THE OIL. 

The records ·of the wells indicate that the 

productive sanqs in this area are singularly The oil here ranges in gravity from a.bout 

free from water. The water is encountered in 1 8° to 26° Baunle. The average gravity of 

the A zone, in the northeastern _part of. the the oil obtained in wells which penetrate both 

area, but that zone is not productive in this the B and C zones and which are not near 

wells that make water.seems to be about 22° area, except possibly in the southwest corner, 

and ·the water sands in it are. easily shut off .Baume. Wells in which the· casing is perby settirig t.he casing somewhat less than 100 forated for only a part of the C zone yield oil 

feet above the top of tlie B zone. In one well of about 26o· Baume. The wells that yield 

near the center of the west line of sec. 5 a heavy oil are chiefly those in which water· is 

water sand lies barely 100 feet above the troublesome. One well at 'first produced oil 

of 16° Baume from the B zone but on being top of the B zone, but in most of the other 

wells in the southwestern part of the area the deepened t~ the C zone yielded oil of 22° 

Baume. lowest water sand. lies somewhat. higher. 

N·ear the center of sec. 5, however, the upPRODUCTION. 

per part of the B zone contains water, or This area has been one of the best producing 

else a water sand rests immediately upon that sections of the field, many wells having had 

zone. This water sand will prove and possi- an initial production of 1,000 to 3,000 barrels, 

bly has already proved troublesome, for many coming in wild and being very difficult to 

of the drillers of wells near this locality have handle. The gas pressure even now, after the 

disregarded the B zone and have drilled down ·area is so thoroughly drilled, is notably high. 

for the C zone, setting their water strings far Many of the wells have had a daily production 

below the water sand just noted. · The relation of over 1,000 barrels for periods of many 

of edge water to. the B zone here. is probably weeks. The field is somewhat spotted, howthe condition of chief importance at present, ever, and some wells that yield only a small 

for :until the position of this water is appro- amount of oil are very close to those that have 

ciated there is serious danger tha_t by the· had large .initial flows. · The dividing line beincorrect handling of some well the upper part tween the area on· the northeast in which the 

of the productive zone will be flooded. B and- C zones have yielded considerable oil, 

What may be termed true bottom water- and the area on the southwest in which these · 

_that is, water in a sand which immediately sands are absent or contain no oil is fairly 

underlies the C zone-does. not seem to be sharp and extends from the vicinity of 

present here, but water i~ plentiful in the Chanslor-Canfield Midway Oil well No. 20, 

Maricopa shale not far below the C zone, -as is squtheastward to the~ vicinity of the center 

shown by the deep wells in sec. 8 and the of the north line of sec. 8. 

Stratton water wells. . This area had its best day in 1911. The proAbout half a mile to 'the north the C zone ductiop. in 1914 was relatively small, the averis composed of a few oil sands separated by age daily· production 'for the wells being very 

barren clays and water- sands. (See descrip- much less than 100 barrels, and 'several of the 

tion of that area, pp. 11Q-i14, and geologic sec- companies were putting the wells on jacks. 

tions, Pis. XIX-XXI.)' So far, however, no It is probable that new wells drilled ~ot too 

water. sands have been encountered in the close to the wells already producing wifi show 

area under discussion, although it is probable a fairly high gas pressure, but big gushing wells 

that as oil is extracted water will work its -way are not to be expected. The initial pressure 

up the dip and may later appear here in the will probably fall off very rapidly in futur~ 

C zone.· As the chief water sand in the area wells, .and their daily production will probably 

to the north, in sec. 32, T. 31 S., R.· 23 E., lies settle down to less than 100 barrela within a 

near the top of the C zone, it is in this part of year. 
. ~- . 

. ' CALIFORNIA COUNTIES-CONTINENTAL AREA • 117 

SUGGESTION8 FOJ"t fUTID{E WORK. 

In the nren. southwest of the diYiding line 

mentioned under the preceding heading the 

wells will derive whatever oil they may obtain 

from the A zone or from lenses in the Maricopa 

shale. This zone will probably yield a very 

small production, indeed, and the wells will be 

similar in character to those in sec. 8. The oil 

will be heaYy. The area lying northeast of 

this line 1nay be further diYided. by a line' 

drawn from northwest to southeast through 

the center of sec. 5. Southwest of this line 

aild northeast of the line first described both 

the B and C zones are productive and water. is 

not troublesome. Northeast of this line the 

upper part of the B ~one contains edge water, 

and great .cn.re shou~d be exercised in setting 

the wn.ter string belo'~ .. this zone and yet not so 

f11r below it as to permit water to enter the 

productive sands that' lie in the lower part of 

the B zone. 

Enough deep wells haYe been drilled here to 

show that the Maricopa shale does not contain 

1nany oil s11nds, although some wells have produced commercial amounts of oil from lenses 

in it. 

Water Inn.y proYe troubleson1e in the northeastern pm·t of the ~rea in· the b11sal part of the 

C zone or just below it, for such water has been 

found in son1e of the wells drilled in sec. 4, just 

to the east; but how far to.the west these water 

sands continue can not be determined in any 

other wn.y than by drilling. 

CALIFORNIA COUNTIES-CONTINENTAL AREA. 

[Southwest corner of sec. 2; southern part of sec. 3; southern 

part of sec. 4; southeast corner of sec. 5; NE. t sec. 9; 

sec. 10; all of sec. 11 except northeast corner; southwest 

cornerofsec.12;W. ;8ec.l3;nJlofsec.14exceptsouthwest corner; northeastern part of sec. 15; northeast corner 

of sec. 23; northernpart_ofNW. tsec. 24, T. 32 S., R. 23E.] 

LOCATION AND OPERATORS. 

The Califori1ia Counties-Continentft.l area 

extends from T11ft northwestward to the vicinity of the California Counties camp, in the 

center' of sec. 4, and embraces a strip about 1 ~ 

miles wide lying just west of the center of 

Midway Valley. The compn.nies operating 

here in 1916 were the Kern Trading & Oil, 

Standard (Continent11l, Equitable, sec. ·10, sec. 

12), CalifOl·nia Counties, Chanslor-Canfield Midway Oil, Union (Equitable, Alvarado, Regal, 

~edrock), Empirs Fuel tQ; Gas, National Pacific, 

Kanawha, s.·· K. D., i\1:arion, Brad, North 

American Consolidated (sec. 2, Oskaloosa), Visalia . Nonassessable, and General Petroleum 

(Continental). 

GEOLOGY. 

The structure of the area is simple, for no 

minor folds break the regularity of the west 

limb of the Midway Valley syncline, upon 

·which this area lie~. The beds strike northwest throughout the area and dip to the northeast ·at a low angle, being -tilted not more than 

106 or 12° in the extreme southwestern part of 

the area and rarely over 3° or 4° in a ·belt at 

least half a mile wide lying just west of the 

axis ofthe syncline. 

The angular unconformity between the 

Maricopa shale and the Etchegoin formatio~ is 

considerable here, as is shmvn by the abrupt 

way in which first the c zone and later the n· 

zone wedge out westward from the axis of the· 

Midway Valley syncline. 

OIL SANDS. 

The productive sands lie entireiy in the 

Etchegoin formation, the Paso Robles containing tar but no productive ol.l sands. No 

well in this area .that has penetrated the 

Maricopa shale has obtained comm~rcial 

a:n10unts of oil from it. In the northwest 

corner of sec. 13 and the· southwest corner of 

sec. 12 the chief oil sands lie considerably above 

the base of the Etchegoin, for in deep wens· here 

Etchegoin fossils have been found in beds 400 

feet or so below the chief oil sands. 

· The beds of the B ~one are relatively fine 

grained throughout this area, and in consequence wells relying upon sands in this zone 

are small producers, for the oil has tended to 

accumulate in the coarser beds below. This 

area fm;ms the northeast end of the belt that 

stretches along the east flank of Twenty-five 

Hill in w~ch the B zone is made up of finegrained material and in which very few wells 

have been commercially successful. 

The productive sands in_ this area lie chiefly 

in the C zone, although the overlying B zone 

contains_ a little oil in the southwestern part. 

The northeastern limit of the area in which 

the B zone contains oil is very irregular. It 

appears to be oil bearing in the southwestern 

part of sec. 10 and in the NE. i sec. 14, two 

areas which lie not more. than three-quarters 

of a mile from the axis of the Midway Valley 

0 
0 

118 THE SUNSET..:-MIDW AY OIL "F_lELD, CALIF .--'-PART I. 

syncline;· On the other .hand, in sec. 4, which for it, and other w~lls go down to the underlies about an equal distance west of the axis lying C zone, all the sands in the B zone being 

of the syncline, the B zone is barren of oil, cased off. with the water sands. Unless' 

except perhaps in the SW. f. A line from a uniformity iJ! setting the water string is 

point a little south of the northwest corner of · established, water trouble is bound to occur · 

sec. 10 through the center of the section and here, if it already has not done so. 

thence to a point a few hundred feet south of. · rn the S. ! sec. 4 the B zone contams water, 

the center of the east line of sec. 14 marks and there seem to be no stray oil sands between 

roughly the eastern limit of the area in .whicl;l the thin sand near the top of the B zone and 

the B zone contains much oil. · .. the C zone; therefore the custom of setting 

Near the center of the south line of sec. 10 the water string pretty c~ose to the C zone is 

the · total . thickness of · th·e productive zone followed. . 

from the top of the B zone to the base of the . Near the center of sec. 10 water is reported 

0 zone is about 500 feet. Approximately an between 50 and 150 feet below the top of the 

~qual thickness of oil sands has been pene~ B zone, but the reports are so yariable' that 

trated in the NE. i sec. 14, but here the drill no more exact estimate of the position of this 

has prob~bly not yet gone through the full wa~er sand can be given. In one well the 

thickness of the C zone. water sand has been mistaken for true bottom 

·The northeastern part of the area is still water, and the lower part of the well was 

. too sparsely drilled to permit any very definite plugged and the u.pper part of the B zone 

statements as t,o the character of the oil sands developed. In·· neighboring wells, however, 

there, except that all the productive sands both the water sand and the upper oil sand 

· lie below the top of the C zone. It is probable in the B zone, from which this well produces, 

that the ·conditions here approximate in a are shut off, and oil is obtained from the C 

general way· those in sec. 32, T. 3.1 S., R. 23 zone. · 

E., and that oil occurs in thi:ri sands scattered. ·Bottom wa.ter . .:.___Bottom water is encountered 

through the beds between the· top ·of the C by relatively few wells in the part of this area 

zone and. the base of the Etchegoin formation, where the sands lie deeper, and it here appears· 

and water sands occur between the several to lie at least 200 or 250 feet below the· top of 

oil sands. There is, howeyer, no reason to the C zone.~ 

believe that. the oil sands will yield oil in · Along the southwestern edge of .the area a 

amount .comparable wit4 that ~btained in w:ater sand lies about 400 feet below the top 

sec. 32, for the wells so far drilled have shown of the B zo:ne. From that locality westward 

· that the oil 'in these sands ~s not under.nearly this water sand approaches closer and closer to 

so 'he~vy pressure as it was in sec. 3.2 when the top of the B zone, and .near the. southwest . 

. the sand' there was firs.t tapped.. corner of sec. 15 water occupies practically the 

WATER SANDS. 

Top and .edge water.-Various wa~er sands 

are recorded above the B zone, but the records 

are so imperfect tpat no general conclusion 

can be reached regarding them.1 In the 

southwestern part of the area t;hey may all be, 

cased off by setting th~ water string a short 

distance above the B zone. The chief trouble 

.from top water is that which is caused by the 

water sandsthat form the edge water for the 

B zone. These sands contain water near the 

· center of sec. io and in the· N.E. ! s'ec. 14. 

:Here, as in other parts of the field where the 

B zone commences to contain water or tar 

sands, the casing in some well~ !s perforated 

· 1 See anaiysis 33, Table 20, and analysis 59, Table 24, Part II (Prof. 

Paper 117). 

top of that zone. As is explained in the description of the SW.! sec.15 (p.126), this water 

sand is believed to mark approximately the 

plane of unconformity between the ~1aricopa 

shale and the overlying Etchegoin formation, 

and the reason that it appears to lie at a higher 

horizon toward the west is that the Etchegoin, . 

in which the B · zone lies, wedges out in this 

direction . 

CHARACTER OF THE OIL. 

There is a distinct difference in the gravity 

of the oil found in the different sands in sec. 

10, and probably a difference in the gravity 

in the same sand in different. parts of the area. 

This ·area is about the eastermnost in which 

the B zone contains oil, anq as some of the 

See analysis 48, Table 22, Part II (Prof. Paper 117). 
CALIFORNIA COUNTIES-CONTINENTAL AREA. 119 

wells produce only from it and others only 

from the C zone, a fairly definite comparison 

of the oil contained in the two zones may be· 

made. 

In the wells in the central part of sec. 9 the 

casing is perforated 'for both the B zone and 

the top of the C zone, and the gravity of the 

oil obtained ranges from 20° to 23° Baume, 

except in one well, which is probably troubied 

by water and from which he~vier oil is obA few wells have had initial productions of 

500 barrels or more, and in 1914 12 wells had 

a daily production of 100 barrels or more. 

The average prodU<~tion in 1914 \Vas ·about 75 

barrels daily. The decrease ·in production 

here does not seem to be very great for the 

deep wells that produce· from the C zone, but 

it is rather high. for those in the B zone. 

SUGGESTIONS FOR FUTURE WORK. · 

tained. · The ·area may be divided by lines running 

Near the center of the south line of sec. 10 from northwest to southeast into three belts 

· the top of ~he B zone does not seem to be very in which the conditions are fairly constant. 

productive and most of the wells derive th~ir · . Along the southwest edge; in a belt about 

oil either from stray sands that lie .in the lower one-third qf a mile wide in s~c. 15 and slightly 

part ·of the B zone or from the C zone. Many narrower in the northern part of sec. 9, the 

of them have been drilled to a very deep part sands from which oil must be expected are inof the C zone, in which the oil is heavy. In. eluded within the B zone. This. zone is usually 

general in sec. 10 the gravity of the normal oil composed of fine-grained sands, and wells 

from the C zone is about 24° to 27° Baume. deriving their oil from it will probably have 

ThQ average oil from the B zone runs 20° to small yields. 

22° Baum6, but closer to the hills, in sec. 15, the The centrai belt is about half a mile wide~ 

B zone seems to yield oil of 14~ to 16° or 17° Its northeastern edge lies alo~ a line drawn 

Baume. In the lower part of the C zone near southeastward from the vicinity of· the south.,. 

the south edge of sec. 10 the gravity of the east corner of the C~fornia Coup.ties property, 

oil is 15° to 17° Baume. Tllis sand is under- passing a little north of the center of sec. 10 

lain by a sand containing water, to the presence and thence to a point a little north of the center 

of which the heavy gravity is probably due. of the east line of sec. 14. In this zone the 

This heavy oil has not been reported· in the c\lief production is obta~ed from the C zone. 

'center of sec. 10. It· may underlie the sand The B zone, however, yields oil, and some of 

yielding 26° oil there, or it may be that the the wells rely entirely upon it for their oil, 'Qut 

sand containing tar in the south edge of sec. in the northeast edge. of the. belt the B zone 

10 contains water in the center of that section. contains· water. This, the "transition belt," 

In sec. 14 the differenceb~tween the oils in is the critical one for this area, for if the water 

the different sands is not so well marked as it is not properly handled here it will flood the 

is in sec. 10. Many of the wells have casings productive sand to the west. Even though 

perforated practically throughout the B and C the sands in the upper part of the B zone are 

zones and yield an oil that ranges in grfJ.vity not productive they should be protected from 

from about 21.5° to 25° Baume. However, in the water sands lying above and below them, 

the southwest~rn part of tllis area the B zone for they are the chief produotive oil sands in 

yields oil of 22.5 ° Baume. the western part of the area. 

In the extreme north end of the area the C The third belt lies northeast of the one just 

zone yields oil ranging from 26° to over 28° described and extends to the axis of the MidBaume. way Valley syncline. In this belt the C zone 

PRODUCTION. 

This area is somewhat spotted, and wells 

located fairly close together in which the casing 

is perforated for the same sand yield very 

different qua:q.tities of oil. 

'l'he bulk· of the oil comes from the C zone; 

the B zone yields oil in the southwestern part 

of the area; but wells depending upon sands in 

this zone are usually small producers. 

yields the oil, the B zone being dry or containing ":"ater. The C zone here appears to contain 

a number of oil sands, which are probably sepa.-

rated by water sands, the whole zone being 

comparable with the productive zone in sec. 

32, T. 31 N., R. 23 E. The upper part of tlie 

C zone ~ppears to contain most of the oil, and 

it is safe to case off all sands above it. It is 

probable that near the axis of th~ Midway Val-
120 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

l~y syncline the whol~ 0 zone is barren of oil or trending parallel to the Midway anticline. 

filled with water. _ · This fold is not shown in the outcropping beds, 

Although.the d~ep wells close to the axis of . but it is indicated by a small topographic rise 

the Midway Valley syncline have tested the near the Chanslor-Oanfield Midway Oil Co.'s 

lower part of. the 0 zone fairly well and have well No. 3 in theSE. i sec. 6, and by the fiatshown that the oil sands here are very lean, that tening of the dip of the oil zones both along the 

part of the zone has nut been tested so thor- east line of se·c. 6 ~nd along the north line of 

oughly hall a mile or so tb the west, and here, sec. 8. In the southern corner of the area, at 

prospec.ting for sands that lie between 250 and · the northwest end of the Spellacy Hill anti400 feet below the top of the 0 zone offers some cline, the beds are steeply tilted, standing in 

promise of reward. places at an angle of 40°. The dip flattens 

rather abruptly, however, and near the center 

of the west line of sec. 16 is not over 15°. 

[Northeastern part of sec. 7; sec. 8; SW. ! sec. 9;· NW. ! Neither the Midway anticline nor the Midoil 

sec. 16; northeastern part of.sec. 17, T. 32 S., R. 23 E.] syncline is very deep, for, although the antiSTRATTON WATER-LOCKWOOD AREA. 

LOCATION AND OPERATORS. 

The Stratton Water-Lockwood area includes 

the south end of the Fellows field and ex.,. 

tends fro~ the old Ohanslor-Oan:fi~ld _Midway 

Oil CaJ}lP in sec. 8 southeastward to the ~orth 

American camp in sec. 16._ The. companies 

operating herein 1916.were the Stratton Water, 

Ohanslor-Oanfield Midway Oil, Hale McLeod, 

Traffic, Midland, and North American Oil Consolidated. · · · 

cline affects the surface rocks as far southeastward as .the center of sec. 8,. the oil sands do 

not make a complete fold, but the anticline 

. and syncline together have resulted only in th~ 

bending of the rocks from a northwesterly to 

practically a northerly strike in the northwestern part of sec. 16 ,and the northeastern 

part of sec. 17. This effect is recognized in the 

oil sands as far eastward as the center of sec. 

15, being shown by a broad bending, convex 

to the southwest, of the underground contours . . GEOLOGY. . (See Pl. III.). It should be noted here that the 

The area ·lies in . the . outer fo.othills of the· Midoil syncline is not so deep as the Twentymain Temblor Range, on the east .ends of the six syncline, w~ch lies northeast of the MidMidway . anticline and the Midoil syncline. way anticline, and in consequence the· Midway 

These folds are in the outer edge of the foot- anticline is more closely allied to the Spellacy 

hills and west .of Fellows trend parallel to the Hill anticline than to the Globe anticline. 

north end of Midway Valley for a distance of Although the oil sands in the Mid oil syncline 

about 4 miles, but in t_he area here discussed contain some water they do not seem to carry 

they swing slightly .towar~ the east and plunge nearly as much· as the sands in the Twentyfairly abruptly beneath the valley, both dying six syncline. 

out so far as their effect upon the surface rocks· The · angular· unconformity between the 

is concerned. To the south the marginal struc- Maricopa shale and the McKittrick group 

tural features similar to these folds are the appears to be considerable here and to be 

Sp.ellacy Hill anticline and the syncline lying especially m.ar~ed along_ the axial part of t~e 

just southwest of it. The.relation of the Mid- Midway _anticline. The lower sands-that Is, 

way anticline to the Spellacy Hill anticline is those of the B and C zones-wedge out ~a~her 

not quite clear, for there is considerable fault- sharply on the northea~t flank of the anticline, 

ing and fracturing of the rocks in the southwest and ov~r a very considerable ar~a th~ only 

corner of sec. 16. The faulting is probably productive sands are those contamed m the 

rather minor, however, and the two folds may A zone. 

overlap in the mariner 'characteristic of these 

small folds throughout the general region. 

At the surface the beds dip at a rather low 

angle even near the axis of· the ::Midway anticline, rarely being tilted over 10° anywhere in 

the NW. i sec. 8. A second very small anticline probably lies just north of the Midway 

anticline, crossing the SW: 1 · sec. 6 and 

OIL SANDS. 

Position.-The chief p~oductive sands in 

this area lie in the basal part .of the McKit.trick 

group, and in much of' the area, especially 

along the axial part ·of the Midway anticline, 

they seelll: to lie practically at the base of the 

McKittrick. The B and 0 zones are certainly 

ill the Etchegoin formation and the basal part 
STRATTON WATER-LOCKWOOD AREA. 121 

of the A zone is also in that formation, for corded as barren. Here the A zone is overfo~sils .have been found in this uppermost zone lain by a zone of tarry sands whose average 

in one well. The upper part of the A zone thickness is about the same as that of the A 

may, however, be in the Paso Robles forma- zone but which has a maximum recorded thick- . 

tion. A small production of fairly light oil- ness of about 400 feet. · Io. places the beds in 

20° Baum.e-is also reported from beds that this zone· are recorded as oil sands but have 

are clearly in the Maricopa shale. yielded no oil and are probably heavy tar.sands. 

Divisions.-Tho oil sands in tho McKittrick They are comparable with the mixed oil; tar, 

group ·may be grouped into two main divisions. and wa.ter sands ·overlying the A zone in the 

Tho upper division, which corresponds to the NW. i sec. 8. 

A zone, has yielded oil in the central and north- In sec. 17 and the northwestern part of sec. 

western parts of sec. 8, the northeastern part 16 the A zone has a thickness of about 250 to 

of sec. 17, the southeast corner of sec. 9, an<:t 350 feet, in places as much as 400 feet. Of this 

tho western part of sec. 16; the lower division, 40 to 80 per cent is barren of oil. The·A zone 

which is the equivolent of the B and C zones; here is overlain by no thick tar z'one comparable 

has ·yielded oil in the northeast corner of sec. with that ·in theSE. 1 sec. 8, but irregular and 

8, the central part of sec. 9, and probably the thi.ri tar sands .are recorded ·up nearly to the 

northeast corner of sec. 16. The oil occurs surface. The difference between the tar sands 

here about as irregularly as in any other part here and those in sec. 8 is pronounced. In the 

of tho field, .its distribution being especially eastern part of this area the A zone appears to 

i.r~egular in the axial part of the Midway anti- be thinner than in the western part and to be 

cline .. This j.rregular distribution is probably overlain by a somewhat thicker tar zone; also 

due in part to the irregular sw·face of the Mari- the water sands appear in the tar zone, here. in 

copa shale and consequently an irregular dis- much the same manner as in the NW. ·1 sec. 8. 

tribution of tho sandy beds that serve as res- The A zone probably contains oil as far east 

orvoi.rs for the oil but also to the fact that this as the center of the SW. ! sec. 5. A few of the 

formation appears to contain considerable older wellS have reported oil in it, although 

water. . those drilled more recently have gone through 

Sandy lenses in the Maricopa shale have the A ~one for the richer sands in the underlyyielded oil in the several wells near the axial ing Band C zones. In· the extreme squth end 

part of the Midway anticline, but these lenses of this area, near the center of the west line of 

are irregular, and as many of them contain sec. 16, the A zon~ is irregular in thickness and 

water rather than oil, they do not promise to apparently contains a considerable amount of 

be a source of much oil. Deep wells at a di,s-. tar sand. Its irregularity in content and thicktanco from the axial part of the ~nticline llave. ness is probably due to the faulting. · 

not found oil in commercial amount in such B and 0 zones.-Although the B and C zones 

lenses. are contoured se.parately in the northeastern 

A zone.-In the northwestern pa:rt of the part of the area· (see Pl. III), they really form 

area, along the axial part of the· Midway anti- a fairly continuous zone, the different contours 

cline in sec. 8, the A zone varies in thickness being· shown. only in, order that the relation 

and reaches a maximum of about 100 feet, but in between the sands in this area and the deep 

much of the area the thickness reported in the sands in the area to the northeast may be 

wells is considerably less than 50 feet. The brought out more clearly. The top of the B 

productive zone is overlain by a zone about 300 zone lies about 400 feet below the top of the A 

feet thick composed of oil' sands, tar sands, zone, but the distance ·v:aries somewhat, the 

and water sands interstratifled with barren two zones being closer in the southwestern part 

clay. In one or two of the wells the beds of the area than in the northeastern part. The 

lying in this upper zone have yielded som~ oil, maximum total thickness of the combined B and 

but most of the oil has come from the 'thinner C zones is perhaps 400 feet. The logs of some of 

m1derlying zone mapped as the A zone. the wells report a continuous succession of bedS' 

In the southeastmn part of sec. 8 the A zone containing oil and gas, but IJ?.OSt of them record 

has an average thiclmess of approximately 200 separate thin oil sands, ·1 0 or 20 feet thick, with 

feet and a maximum of a little over 250 feet, a few 50 feet thick, interstratifled with barren 

and of this about 50 per cent is usually re- shale. The beds reported to be oil b.earing 
122 THE SUNSET-MIDWAY OIL FIELD,. CALIF.-PART I. 

usually form less than 40 per cent of t.he whole The water encountered is distinctly a· sulphur 

zone. For the i:nost part the upper beds in water and in at least one well has yielded. a conthis zone-that is, those .which would be cor- siderable flow~ 1 These water sands are rerelated with the B zone_:.do not appear to con- ported to occur within 50 or 80 feet of the top 

tain much oil, and several. of the wells, espe- of the A zone. · A somewhat similar condition 

cially those in the eastern part of the area, have prevails near the center of the west line of sec. 

been drilled through them without· ~ding oil. 16, although the water sands there do not seem 

This area lies at the north end of the belt that to be so abundant nor so troublesome as in the 

extends northwestward froni Sp.ellacy Hill N. t sec. 8. They are reported, however, to 

through the outer foothills, in which the Bzone occur as low as 50 feet abo·ve the top of the A 

contains very little oil or is barren. This bar- zone. 

renness~is believed to be due largely to the fine Edge water.-The A zone contains edge 

grain .. of the b.eds that compose the B zone in water in the 9uter part of the area in which it is 

this part of the field. The· combined B and Q .. contoured· on Plate III, edge water appearing 

zones are wedged out rather sharply by the un- not only in the uppermost part but also practiconformity, and it is probable that they d~ not cally in the central part of the zone. In a·belt 

underlie much-of the territory lying west of the that extends through theN. t sec. 16, the southarea· where· they' are contoured on. the map western part of sec. 9, and theN. t sec. 8 edge 

. <Pl .. III). · water will probably prove troublesome in the 

Oil sands in the 1J1aricopa shale.:_A consid- A zone. East of this belt the edge water in the 

erable number of wells hav-e been drilled below A zone may be considered as t·op water for the 

the productive sands in the McKittrick group~ B and C zones. There, however,' water sands 

According to reports, some of them have found occur v-ery low in the A zone, and water should 

oil in the underlying Maricopa shale, and a few be shut off a short distance above the top of 

have mad~ a definite production from these the B zone. Nowhere in this area does the B 

sands. It is not possible to recognize any reg- zone appear to contain water. 

ularity in the. distribution of these sands, a:o.d Bottom water.-In the western part of the 

it seems certain that they are lenticular masses area-that is, in the area where the A zone furin the Maricopa shale which have no v-ery great nishes the oil-many wells have encountered 

areal extent. The lenses that hav-e so far bottom water below the productive zone, at 

yielded commercial amounts of oil are located va~ious horizons in the Maricopa shale.2 

along the axial part of the Midway anticline. 

G:rain.~The productive sands range in char- CHARACTER OF THE OIL. 

acter from coarse gravelly sand. in which the · The A zone yields oil that ranges in gravity 

fragments are as much as a quarter of an inch from. about 12.2° to 17.9° Baume and averages 

in diameter and possibly even $Ome larger down between 13 ° and 14 °. The B and C zones yield 

.to fine clays. In places the sands are composed oil that ranges from 18.5° to 23° and averages 

chiefly of shale pebbles embedded in a mass of a little lighter than 21°. One well, in sec. 8, 

clay, but wells encountering "sand'' of this gives 18° oil from -the deeper zones, but it is 

type yield a v-ery small production and many close to a deep well that got bottom water. 

of them hav-e been abandoned. Some pf the 

sands ·in the Maricopa shale ·are· remarkably 

even grained granitic sands coll).posed of fragmeD:ts 1 or ·2 millimeters in diameter. 

WATER SANDS. 

Top water.-Top water is. rather troublesome 

in the northern part of the are a, in the N. t 

sec. 8, being especially so in the wells. that depend on the A zone for their production. As· 

has been described ,in the discussion of the A 

zone, the productive sand here is overlain by a 

. zone of oil, tar, and water sands 300 feet thick. 

PRODUCTION. 

No well in this area ever had a v-ery large 

daily product~on, and although some wells at 

first yielded 200 to 400 barrels daily, most of 

them have yielded less than 100 barrels. The 

average production in 1914 was between 15 and 

20 barrels per well per day. Although the oil 

sands are relatively close to the surface near 

the northeast corner of sec. 17, the wells there · 

have produced about &s ·much oil as any of the 

1 See analysis 35, Table 20, Pa.rt II (Prof. Paper 117) . 

2 See analyses, Table 24, Part II (Prof. Paper 117). 
THE SUNSET-MIDWAY OIL :FIELD, CALI:F.-PART I. 123 

wells. elsewhere within. the area, and this de- part of the area. Bottom water does not 

c~ea~:Q ·i~1 prqd uction :~s. rather less tha~ tpa t of seem to unde~lie the C zone ·very close! y ,· howthe wells which draw their oil ,.from, the .sa:pd e.ver, althpugh it was encountered in the Mariwhere it !~.~ore deeply buried. . · · ~9Pa.sh~e in the deep well just mentioned. 

SUGGESTiONS }"'OR }"'UTURE . WOR·K. ' ·, ·, . LOCKwo'OD-TALARA AREA. 

·.~.: ]:;; .th~i:·~e~ in which only the A zone is.c.on- [Sout4~;~st ·~orner.of s~c: 14;. SW. t, NW. t, and all of S.! 

toured.on Plate III small wells will prove t;he:r~.e . except the northeast corner sec. 15; SE. t sec. 16; NE. t . sec. 21; all of sec. 22; all but'northeast corner of sec. 23; . 

from now on, for the gas pressure, which c,a.used ·~ ., sw.· t and s. ! NW. t sec.' 24; and northeast edge of 

some of the wells to give a considerable. produc-· .. sec. 27, T. 32 s., R. 23 E.J 

tion originally, has now beengreatlyreduced, and 

itis to be expected thatthepro~uctio,nof thenew 

.·wells will be approximately the .same ~ . the 

present production of the old·. wells.· Deep· 

drilling in this part of the field, e:x;cep.t possibly 

along the axial part of the Midway· anticline, 

will probably not prove profitable, for although 

the Maricopa shale .evidently c.ontains some 

lenses saturated with oil, these lenses are so 

irregularly distributed that prospecting. for 

them will be very costly and the percentage of 

failw·e large. Moreover, these lenses do not 

seem to contain very much oil, certainly not in 

amount at all comparable with that . in the 

McKittrick group. · 

Top water is troublesome in this area, being 

especially so in the northern part of sec. 8, and 

should be shut off by setting· the casing oilly a 

short distance above the top· of the A zone. 

Along the outer margin of the area where the 

A zone is contoured edge water appears in that· 

zone. 

In the area which lies east of a line drawn 

from a point near the center of the north line of 

sec. 8 to one a little south of the southwest 

corner of the Traffic property and thence southeastward to a point somewhere between North 

American wells Nos. 67 and 71 in ~ec. 16 sands 

in the B and C zones yield the oil produced, 

and the A zone either is dry, is filled with water, 

or contains tarry oil or asphal.t. In or4er to 

protect the B and C zones from the water in the 

A zone the water string should be set only a 

short distance above the top of the B zone. 

The B and C zones have been drilled completely through in only a single well. This 

well shows that the combined zones are probably not much more than 350 feet thick and that 

below them the Maricopa shale is· of about the 

same character as it is near the Midway anticline. It is therefore probable that wells 

drilled deeper than 350 ·feet l?elow the top of 

the B zone will ~ot yield much oil in the e~tern 

. LOCATION AND OPERATORS. 

The Lockwood-Tala:ra· area occupies a belt 

about 1! miles wide on the outer edge of the 

foothills of the main Temblor Range southwest 

of Taft and embraces the north end of the 

Twenty-five Hill field. It is . bounded on the 

southwest by the topographic depression that 

lies on the southwest side of Spellacy Hill 

(Twenty-five Hill) an~ on the northeast by the 

edge of Midway Valley. The companies operating or holding land here in 1916 were the 

Visalia Nonassessable, North American (Oskaloosa, sec. 16, and Lockwood), Marion, General 

Petroleum (Foxtail, Sybyl, and B. A. T.), 

Brad, Oleum, J:ade, Chanslor-Canfield Midway 

·oil, Union (Alvarado), Fairbanks, Burk, Combjnation Midway, Wilbert, Buena Fe (Amador 

Usona, Alpine, Amador West 40, Amazon, and 

Mountain Girl), Indian & Colonial, Producers 

Guaranteed, Griffith, Knob Hill, Babcock, 

Palmer Union, Traders, Cheney Stimson, and 

Jamison (Talara). 

GEOLOGY. 

The general geologic features in this region 

are identical with those in sees. 25 and 26, 

just to the southeast, and the· productive zone 

in the two areas is. practically the same. The 

two areas differ, however, in that in the northa~ o·ne, here under discussion, the productive 

san.ds in the McKittrick group are virtually 

restricted to the northeastern flank of the 

Spell~cy Hill anticline, whereas in the southern 

area the McKittrick -sands are prodlJ,ctive both 

on the northeast and on the southwest flank 

of that fold.· · On this account the two areas 

are described separately. 

The dominant structural feature here is the 

Spellacy Hill anticline,· which trends in a 

south~astward direction through the central· 

part of the area. Southwest of the axis of this 

fold is . the .shallow and irregular syncline that 
124. THE .SUNSET-l~UDWAY OIL FIELD, CALIF.-PART I. 

determines the topographic depression in the corner of sec. 27.. This interruption is minor, 

northeastern part· of sec. 27, the southwestern however, and the two parts may really be conpart of 3ec. 22,. and the northeastern part of sidered a single trough .. 

sec. 21, on the southwe.st side of Spellacy Hill. . The surface rocks here all belong to the 

~arther southwest, beyond the axis· of this McKittrick group, except in the center of sec. 22 

trough, rises the higher part of the Temblor and in an irregular strip along the southRange, in which are exposed the older Tertiary western edge of the area, in which the. soft 

foJmations that lie below the beds that have diatomaceous shale of the underlying Maricopa 

·yielded oil in the Midway field. The Spellacy shale is exposed. It is difficult to determine 

Hill anticline is a well-marked fold that ex- whether the lower par~ of the McKittrick, 

tends from the southwe.3t. corner of sec. 16, which crops out here,· is Etchegoin or Paso 

T. 32 S., R. 23 E., to the we.3tern par-t of Roble3 .. The Paso Robles formation certainly 

sec. 30, T. 32 S., R. 24 E. Near the northwest crops out near the center of the north line of 

end the fold is broken by a consider·able number sec. 22, for fresh-water fossils were collected 

of minor faults, and its relation to the Midway there; but between that point and the outcrop 

anticline, which lies to the north, is riot clearly of the diatomaceous shale of the Maricopa 

shown. It is probable, however, that the two nothing was found in the arkosic sands, gravel, 

folds overlap in a manner similar to that shown and clay which crop out along the creek that. 

by the small folds in this general region, would aid in determining the formation to·, .. 

although possibly the Spellacy Hill anticline is which they belong. · .... 

really joined to the Midway anticline by an Except at the northwest ·end of the Spellacy 

arch that trends north through the eastern anticline, near the southwest corner of sec. 16, 

part of sec. 17 and the western part of sec. 16. the area seems to be free from faults. The 

The faults that affect the beP,J near. the south- irl.'egularity in the distribution of the oil sands 

west corner of sec. 16 are ·probably not deep in parts of this area has been thought by many 

nor of great throw, bu·t ~hey have so broken the persons to be due to faulting, but this irregularbeds that the oil occlirs in an irregular .zone. ity is really caused chiefly by the lenticular 

T~e Spellacy Hill anticline is slightly asym- bedding and by the fact that the oil sands· that 

metric. The southwest flank is short, for in are productive along the' axial part of the 

most places the axis of the adjoining syncline Spellacy Hill anticline are not productive for 

. lies only about a quarter of a mile from the .more than a very short distance down the 

axi.3 of the anticline, and the dips here. decrease north flank of the fold, for oil this flank a sand 

abruptly from a maxiinum of about 25° near wedges in below· the sand that is productive 

the axis of the anticline. The northeast flank along the Spellacy Hill anticline and above the 

is longer and the dips ·on tha't side decrease less ·top of the Maricopa shale, and it is this sand 

abruptly. Near the axis of the anticline the that furnishes the oil. 

beds are tilted to angles of 25° or 30°, but at 

the edge of the hills·, abo~t three-quarters of a 

mile northeast of the axis, the dip is about 15°. 

Farther northeast the beds are not expm:ed, 

but the attitude of the oil sand.;;, as inferred 

. from the well records, shows that the dip decreases rather abruptly here, the beds assum:ing 

the very low dip characteristic of them beneath 

other parts .of the valley. In the foothills the 

attitude of the beds near the surface is not 

exactly like that of the underlying oil sands,. 

for in general the oil sands here, as in other 

parts of the ·area along the foothills of the main 

range, appear to be less steeply tilted than the 

·surface rocks. 

The syncline southwest of the Spellacy anticline is not regular but is broken into two parts 

by a small ·a:n,ticlinal fold near the northeast 

OIL SANDS. 

The productive sands in this area are those 

embraced in the A and B zones, the deep ·c 

zone.not being present. 

The A zone is by far the more important, for 

from it' comes the oil that is obtained in the 

area that extends along the axial part of the 

Spellacy Hill anticline and for a distance of 

about half a mile doWn the northeast flank of 

that fold. . . 

The B zone furnishes the oil produced in the 

southwestern part of sec. 15, the northeastern 

part of sec. 22, the northeastern part of sec. 23, 

and the southwestern part ofsec. 24. In these 

areas the A zone is productive· in places, but 

the main yield ·comes from the lower sands. .· 

On the map the R zone is contoured well into 
LOCKWOOD-TALARA 'AREA. 125 

the central part of sec; 22, but in this section thinning at the top and not at the bottomit really forms with the overlying A zone a that is, the top of the zone containing oil does 

thick succession of oil sands and barren ·strata not mark a stratigraphic plane but a plane that 

that are not readily divisible into definite toward the north cuts lower and lower into the 

parts. stratigraphic section. 

A zone.-In the extreme northern part of B zone.-In the northeastern part of sec. 23 

this area (sec. 16) the A zone averages about and .the southwest corner of sec. 24 the pro200 to 250 fee't in thickness, and in most of the ductive zone splits up into distinct oil sands 

well logs fully half of this thiclmess is recorded which are· ·separated from one another either 

as oil sand. by barren strata or by sands containing water. 

Tti sec. 21 the productive zone has a maxi-· In the eastern edge of the area just outlined 

mum thiclmess of almost 700 feet, of which the total thiclmess of the productive zone is 

usually half or more is recorded as oil sand. approximately 700 feet, of which the upper 300 

The upper 200 to 250 feet is probably in the feet forms the A zone and consists of alternatMcKittrick group; the lower part is almost ing oil sands, w·ater sands, tar sands, and barren 

·certainly in the Maricopa shale. strata. Below this comes the B zone, which 

In the northwestern part of sec. 22 the pro- has yielded the oil obtained here. The B zone 

d~ctive zone seems to be less than 300 feet is approximately 200 feet thick near the souththick, and usually at this depth below the top west corner of sec. 24 but reaches a maximum 

of the A zone water is encountered. Many of of about 400 'feet near the center of the section. 

the wells penetrate only 150 to 200 feet of Only about 25 per cent of this thiclmess, how:-

strata in this zone. In the central part of sec. ever, is labeled oil sand in the drill records. 

22 the water that is encountered near the The B zone appears to be rather fine grained 

NW. i sec. 22 is not recorded, and a few of in most ·of the area and not to contain very 

the wells here have been drilled as much as 500 m~ch oil, arid wells in the part of the area that 

feet below the top. of the A zone wi~hout is dependent upon this·sand for its oil have not 

encountering water. The logs of these wells been large producers. · The belt in which this 

record oil sands through a thiclmess of 300 to condition prevails is about a mile· in 'width and 

350 feet, and many of them record at least 70 extends .along the east flank of Spellacy Hill 

per. cent of. this thickness as oil sand. (1:\venty-:five Hill) from. the vicinity of the 

In ·the NE. i sec. 22 the maximum thickness north line of sec. 25, T. 32 S., R. 23 E., nor.thof the productive ·zone is about 300 feet. The ward at least as far as s~c. 9 of the same 

productive zone here commences to show a township. 

considerably greater amount of interstrati:fied Throughout the part of the area in which it 

barren clay than is shown nearer the axis of the is contoured on the inap (Pl. Ill) the B zone is 

Spellacy I-Iill anticline. .In the southwest cor- usually at least 250 feet thick. 

ner of the section the same condition prevails Grain of the oil sand.-The sands contained 

as in· the NW. !, but farther east edge water in the zone are variable in grain; some of the 

appears in the A zone. beds contain cobbles· and boulders several 

In the SE. i sec. 22 the producti'Ve zone is inches in diameter, but most of them consist of 

somewhat thicker than it is in ·the NE. !, medium to fine grained sand. 

probably because the lower measures lie in the The B zone is very fine grained in places, 

~1:aricopa shale and not because the McKittrick notably in the central and southeastern parts 

group is thicker here. of sec. 23, where it is called "shale" in the 

In the southeast corner of s·ec. 23 the con- drill records and the oil is said to be "shale 

ditions are much the same as in the SE. l sec. oil." . 

22. The A zone here has a maximum thick- The difference in· character between the proness of about 400 feet. The upper 100 to 150. ductive sands, along this northeastern pa.rt 

feet near the axis of the anticline in the ex- of the area (the B zone) and the productive 

treme southwest corner is in places called tar sands along the axial part of the anticline (the 

sand. The productive zone is progressively A ·zone) has been noted by the drillers and 

thinner northward, and near the north line of explained ·by them as due to a fault which 

the quarter section it contains only about 150 trends northwest a little northeast of the crest 

feet of beds. This thinning is probal:Hy a· of the hill. There appears to be no necessity 
126 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

for assuriiing the -presence of such a fault, and ·of the SW. ! sec. 15. ·Southwest of this belt 

there is no direct eviden~e of its eXistence. water does _not occur dose below the producWATER SANDS. 

tive sands, and wells have been drilled 'several 

hundred feet into· the underlying shale without 

Top water.-True top water is not trouble- encountering water. The top of this "bottomsome anywhere in this ·area. Along the aXial water sand," or zone containing water sands, 

part of the anticline the only top water re- lies between 250 and 400 feet beneath the tqp 

ported is purely surface water occurring within of the A zone, the thickness of strata separating 

a short distance ·of .the surface. o ·them being dependent upon the position in the 

Edge water.-The chief trouble with so-called· area. T4us, near the center of the north line 

top water is. concerned with what- is really edge of the NW. ! sec. 22 the top of the· ''bottomwater in the A zone. Water is ·encountered in water sand" and the top_ of the A zone are 

this zone in the southern part of·sec. 15 (below some 275 feet apart, whereas in theSE. i sec. 

the true top water just noted), in the northern, 22 they are between 330 and 400 feet apart. 

and southeastern parts of sec. 23, and the south- Near the southeast corner of sec. 16 the bottom 

· western part of sec. 24. In sees. 23 an~ 24 the water is hardly 250 feet below the top of the A 

A zone is composed of ~hin oil sands which I zone arid seems to occupy practically the posi0 

Approximate scale 

Yz 

. tion of the top of the B zone. 

The most reasonable explanation of this occurrence· is that 

water from a sand in the Maricopa shale has worked its way 

out of the truncated beds of 

Surface 

rMile 

~------~------~--~----------~ 

. that formation along the plane: 

of unconformity into the overlying oil-bearing beds of the 

McKittrick group. It is 

probable that wells a short 

distance northeast of this 

locality which rely upon the B 

FIGURE.14.-Diagram showing possible explanation for occurrence of water in the B zone in zone for their production will 

the northwestern part of sec. 15, T. 32 S., R. 23 E .. Arrows indicate direction of m.ovement be troubled by' \Vater in a · of edge water. · rather peculiar manner-that 

contain·heitvy oil and which in many'welllogs is, edge water will work down the dip froni the 

are recorded as tar sands, together with water southwest as well· as up the dip from the. 

sands and interstrati:fied barren clays. _The' northeast. This condition of. affairs is shown 

~owest water sand recorded here lies about 80 diagrammatically in figure 14. 

· feet above the top of the B zone. There is · In places 'this sand· affords an extremely 

hardly a well in this area that does not record strong flow of water, and it is said that from 

water in the~ zone. It seems very doubtful one well more than 5,000 barrels of water a day. 

whether the A zone will prove or has 'proved . was lifted without making any impression upon 

productive much farther east than .the line the water level. At present, however, a conmarked by the + 400-foot con tour ·on this· sand. siderable number ·of the wells are raising oil 

(See Pl. III.) · and water with air lifts, and it is said that a 

Bottom water.-A· persistent wa.ter· 1 sand very considerable lowering of water level ·is 

l.mderlies the productive oil sands in the central observab1e. · · 

part of the area, in a belt marked roughly on The belt beneath which bottom water 

the southwest by a line drawp.· between the occurs. closely below the productive zone concenter of .theW. t NW. i sec. 22 and the :p.orth- tinues both northwestward and southeastward 

east corner of the Cheney -Stimson property and beyond the limits of the area here. described, 

on the northeast by an approximately ·parallel but the water sand is probably more troubleline drawn through the center of the. south line some here than in the neighboring areas. The 

1 See analyses, Tables 24 and 25, Part II (Prof. Paper 117). approximate position of the top of the· water-
LOCKWOOD-TALARA AREA. 127 

bearing zone is· shown by the sketch contours 

on Pia te XXXVIII. 

' JJEDS ABOVE THE A ZONE. 

In the northwest end of this area a tar zone, 

about 150 to 200 feet thick, rests immediately 

upon the A zone. In a few of the wells stray 

tar sands are recorded within a few feet of the 

surf ace, but on the 'whole the chief tar seems 

to extend less than 200 feet above the top of the 

A zone. This general condition prevails in 

sees. 16, 21, and 22. ·In the southeast end of 

the area, in the SE. t sec. 23 and the southwest corner of sec. 24, the tar sands occur in 

thin streaks scattered through the beds· for a 

distance of several hundred feet above the A 

zone. In this part of the area the A zone 

really takes. the place of the tar zone resting 

upon the productive sand-that is, the B zone. 

BEDS BELOW THE PRODUCTIVE ZONE. 

· B zone.-In the southeast end of the are.a 

the B zone yields oil bet~een 17° and 20° 

Baume, or possibly as light as 23° Baume; the 

average is a little less than 20° Baume. To the 

fine grain of the beds.here is probably in a measure due the light gravity of the oil as contrasted 

with the heavier gravity in the A zone, but 

the greater thickness of the cover is also one 

cause. 

In sec. 15 the B zone has yielded oil that 

ranges in gravity between 14° and 16.5° 

Bai.une and averages 15°. This oil is somewhat heavier than that in the B zone in· sees. 

23 and 24, and it is possible that some of the 

wells may derive a part of their oil fr~m the A 

zone and .the product thus not t>e characteristic of the B zone. However, water sand 

underlies' the B zone very closely here and the 

nearness of the water may account for the 

greater specific gravity. · 

Along the a..-Tial part of the Spellacy Hill PRODUCTION. 

anticline the deep wells entering the Maricopa shale have found that sandy lenses in the Along the axial part of the Spellacy Hill anticline the A zone originally contained oil under 

upper part of that formation contain oil, and 

also that the deeper sanqs usually contain considerable pressure, and many of the wells 

first drilled had an initial production between 

water, but that water does not seem to lie 200 and 400 barrels daily, but the field is now 

.close to the base of the A zone anywhere in 

so thickly drilled that in most of the wells the 

this pMt of the Twenty-five Hill field~ The pressure is practically negligible and in 1914 the 

Maricopa shale here seems to be composed chiefly of brownish shale, doubtless diatoma- average. daily production per well was between 30 and 40 barrels. 

ceous shale, with some beds of sand, a few 

beds of boulders or cobbles, and also some No well in this area produced from· the C 

zone alone, although some of the wells in the limestone shells. In the east end of the area 

very eastern edge may have obtained p~rt of the Maricopa shale is recorded· as chiefly brown 

sand, with relatively little shale. This differ- their oil from this deeper zone. . . In the southeastern ·part of sec. 23 and the 

ence in the records may be due simply· to the 

fact that they were made by different drillers, southwestern part of sec. 24 the wells were 

mainly small producers, although one or two 

but it is so marked that probably the Maricopa have had an in~tial production of 200 or 300 

shale here is really much more sandy. Moreover, the Maricopa shale in the east 'end of the barrels daily. Th~se larger wells ·evidently 

area contains much more water than it does produced from small lenses of san9. inclosed in 

the sandy shale. Most of the wells here get close to the axis of the Spellacy Hill anticline. their oil from fine sandy shale characteristic 

CHARACTER OF THE OIL. of the B zone, and, although small producers, 

. A zone.-Oil.in the A zone ranges in gravity they show a rather slow rate of d~crease. 

from about 12° to 15° Baume; the average of 

the oil produced in 1914 ran about 13.5°. The 

original oil, although somewhat lighter, was 

rarely lighter than 15 ° Ba~e. The increase 

in the specific gravitY (decrease in degrees 

Baume) is doubtless due in part to the decrease in the qua:Q.tity of gas in ~his area, but 

it is also due in part to the infiltration of 

bottotu water. 

SUGGESTIONS FOR FUTURE WOJtK. 

The area near the axis· of the Spellacy Hill 

anticline is practically drilled up ·so far as oil 

sands in the McKittrick group are concerned. 

The wells farther southwest-that is, southwest 

of the wells now producing but still on the north 

flank of the Spellacy Hill anticline-will probably obtain very little if any oil in ~he A zone. 
128 THE SUNSET-MIDWAY 'OIL FIELD, CALIF.-PART I. 

wells drilled on the southwest side of the axis . erable quantity of oil except along the axis of 

of th~ anticline will. probably find that zone en- the fold, and here only in its upper part. 

tirely dry of oil. New wells drilled in the cen- Deep drilling either here or elsewhere in this 

tral part of the area will doubtless have an area for sands in this formation will probably 

~nitial production practically equal .to the not be found. very profitable. Oil sands like 

present yield of the wells now producing in the those encountered by the deep· wells of the 

:·immediate neighborhood. · J. M~ S. and C~lifornian Amalgamated comIn the outer or northeastern edge of the area panies are about the best that should be ex~ 

·in which the A zone is contoured that zone ·pee ted from the Maricopa shale here. 

contains· water and probably will not yield The chief water troubles of this area are 

. much if any oil. The exact positio:p. of the those concerned with the· water· sand which 

southwestern limit of the area beneath which underlies the A zone and into which so many 

edge water occurs in this zone varies from wells in the .axial part of the field have been 

place to place, but it is outlined roughly by· a drilled. The water from this sand has entered 

line drawn. southeastward from a point near the overlying productive san.d and has even 

the center of the north line of sec. 22 to the flooded many of the wells that have not been 

center of the east line of that section ari.d thence drilled deep enough themselves to encounter 

to· a point a short distance east of the center of bottom water. A. comparison of the depth of 

the so~th line. of ·sec. 23. the wells in this part of the field with the sketch 

The B zone, from. which the production is•to contours, shown on Plate XXXVIII, indicating 

be expected in the northeastern part of the the approximate position of this'bottom water 

area, is rather fine grained and has so far in sees. 22 and 23, is instructive. Any well 

proved very spotted.· This zone does not ap- that has been drilled below the depth at which, 

pear to be underlain very closely by water as indicated on this map, bottom water is to " 

.sand. except in the southwestern part of the be expected should be critically examined, for 

area in ·which it is co:p.toured. It seeins as if if the well did not. encounter bottom water 

the sands of this zone here are truncated or when it was drilled it is possible that water· 

rather wedge out at the unconformity, and may 1llak~· its appearance later.· 

water which has probably come from sands in · Much of the northeastern. part of this area 

the Maricopa shale has worked its way into the has virtually been condemned on account of 

top of ~he B zone. Th:Us there is here a pecul- the dry holes scattered through it. It is praciar condition of edg~ water ·working into th~t ti~ally ·certain, however, that a very considersand from· the southwest, as well as· the ord1- able quantity of oil occurs here in the B zone, 

nary 'edge water which occupie~ the sand on the and that, although this sand is so fine grained 

northeast. (See fig. 14.) Th1s fact, together that no large wells will be obtained here, with 

with the fact that the sands in the B zone are the increase· in the price of oil this area will 

very fine gra~ed, explains the pre~ence of the prove profitable ground for prospecting more 

barren belt that extends northwestward from thoroughly. 

the !lOrth ~nd of Spellacy Hill, in sec. 24, to the 

vicinity of Midoil, in sec. 9. The fine grain of DUNLOP-SECTION TWENTY-FIVE AREA. 

the beds and not the presence of water, how- [All of sec. 25 except the northeast corner; sec. 26; NE. t 

ever, is probably the chief factor determining sec. 27; N. t sec. 35; N. t sec.·36, T. 32 S., R. 23 E.]. 

the lack of oil in this belt.1 . 

The sands encountered in the lower parts of· LOCATION AND OPERATORS. 

the deep wells that have been drilled near the The Dunlop-Section Twenty-five area includes 

axial part of the Spellacy Hill anticline lie in the southern part of the Twenty-five Hill field, 

the Maricopa shale. This formation, ho~- em~racing the crest, ·the south flank, and ·a 

ever, does not appear to contain any consid- strip on the southwest side of Spellacy (Twenty-

. ·five) Hill. (See Pl. X..."'UCIX.) It was one of 1 By fineness of grain is meant not the real size of the grain but the' . 

relativesizecomparedwiththegrainoftheadjacentbeds.' Asamatterof the.first parts of the Midway field to be prOSfactthesebarrenbedsalongtheflankoftheSpellacyanticlineareno:finer pected and is noW more thickly drilled than 

than the rich oil sands in the Buena Vista Hills. There is this differl)nce, 

however, that the oil Sands in the Buena Vista Hills are surrounded by any other pa.rt of the field. The companies 

bedsofstill:finergrain, whereas~he:fine-grained beds that compose~heB operating here in 1916. were the. Opal, Safe, zone along the flank of the Spellacy anticline are adjace::1t to beds of 

· muchcoarsergra!Jlin which theoilhas, quite naturally, collected. West Side, W. T. & M., B. H. C., Cresceus, 
U. S. GEOLOGICAL SURVEY 

28 

PROtJUCERS 

GUARANTEED 

3+ 

27 

G. P CO. 

( B . A . T ) 

+soo~l.cr'­

NORTH AMERICAN 

OIL CONS. 

119° 30' 

l \9° 281 PROFESSIONAL PAPER 116 PLATE XXXVIII 

MAP OF NORTH END OF TWENTYFIVE HILL, SHOWING BY SKETCH STRUCTURE CONTOURS 'l'HE UPPER SURFACE 

OF THE BOTTOM WATER SAND AND OF THE J. M. S. SAND, T. 32 S., R. 23 E., CALIFORNIA 

Well s are t hose show n on Plate Ill 0 c==:. 

.1. 

S c ale 2;.,ooo 

1

:MiJ.e 

t 

Surface contour interval 20 feet 

Structure contour intervallOO feet 

Datum is ·mean sea level 

----------- Bottom water sand 

J . M. S. sand 
• 

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XXXIX 

SOUTH END OF TWENTY-FIVE HILL, MIDWAY FIELD. 

Looking north from point ncar Los Pozos well, in sec. 36, T. 32 S., R. 23 E. 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XL 

A. SUMP IN FOOTHILLS FILLED WITH OIL FROM MIOCENE NO. 1 WELL IN 1914. 

Note the old "high-water" mark made by oil of Lakeview No. 1 gusher, as shown iu B. 

B. SUMP FILLED WITH OIL FROM LAKEVIEW NO. 1 GUSHER, OCTOBER, 1910. 

This sump was consLcucted by throwiug a dam across a sharp gulch north of Maricopa. Photograph by W. C. Mendenhall. 
,.. " ., . 

DUNLOP-SECTION TWENTY-FIVE AREA. 129 

General Petroleum (Nevada Midway, Scrongo, 

and Bankline) ,. Section Twenty-five Oil, Seaboard, Paraffin, Princeton, Pierpont, T. W.,· 

Millie Francis, Tamalpais, Elkhorn, Pozos, 

Mascot, Carbo, Wilbert, Dunlop, March, Californian Amalgamated, J. M. S., Malayan 

Crude, Union (Pebble), Victor, and North 

American (Mount Diablo). 

GEODOGY. 

northeast corner of sec. 31 suggests that it 

continues approximately that far. This fold 

is, however, but a minor feature on the south 

flank of the main Spellacy Hill anticline, for 

it can not be traced 'into a comiection with 

the main fold near the northwest corner of 

se·c. 26. so·. far as its effect on the oil sands 

is concerned it may safely be disregarded. 

The near approach of the syncline, which is · 

here ·really a major structural feature, to the · 

The chief structural feature here so far as small anticline shows the minor importance of 

the occurrence· of oil is 'concerned is the Spel- the anticline . 

. lacy IIill anticline. This fold is the central On the north flank of the Spellacy Hill antione of the group of small folds that lies along cline the dips are regular and vary between 10° 

the west side of Midway Valley and like all and 15°. In sec. 26 the axis of t}le syncline 

these small folds it trends sOJ;newhat obliquely which separates the Spellacy' anticline from 

to the course of the main range. It heads near the n1ain range lies more than half a mile 

the southwest corner of sec. '16 and extends to the southwest, and in this section the dips 

almost due southeastward for about 3 miles to ·a are fairly low and regular from the axis of the 

poii1t near the center of the e,ast line of sec. 26, anticline southwestward to the axis of the 

where. it changes to a more easterly trend and syncline.· Ne~r ·the southwest corner of sec. 

continues through the central part of sec. 25, 25, where the axis . of the syncline swings 

T. 32 S., R. 23 E.,. into sec. 30, T. 32 S., R. rather abruptly to .an easterly· tre:q.d and 

24 E. East of the ce:nter of sec. 25 the fold toward the east approaches more and more 

plunges rather abruptly, and it dies out closely the axis of the small anticline described 

in the central part of sec. 30. The true form above, the dips are son1ewhat irregular and 

of the east end gf the fold is not very well in 'places as much as 30°. The syncline is a 

shown in the outcrops. The axis of the main fairly sharp _fold, for the beds turri abruptly 

fold may be traced at the surface as far south- and only a few hundred ':feet west of the syneastward as the center of the NW. i sec. 26, but clinal axis are tilted to angles of 30° or more. 

from that point eastward it is difficult or even The surface rocks in this area are in the 

impossible to recognize a southward dip in the McKittrick group and probably entirely in 

outcropping beds anywhere in the south-central the-Paso Robles· formation except for tl!e beds· 

part of sec. 26 or the southern part of sec. 25. that crop out in a narrow belt in the· southern· 

The structure of the productive zone shows, · part qf the N. ! sec. 35 and in the southern 

however, that the axis of the main fold trends part. of theN. ! sec. 36. In this belt the beds 

almost directly eastward through the central are believed to be in .the Etchegoin forn1ation. 

part of sec. 25 and northeastwa~d through sec. The approximate line of ·sepa~ation between 

30. If the structure is viewed as a whole, the the Etchegoin and Paso Robles is indicated ·on 

east end o~ the fold may be considered a broad the geologic map· (Pl. II). · 

anticline which plunges faidy abruptly toward Many of the· operators working in this part 

the east and whose axial part lies in the central of the field believe that the beds are n1uch . 

part of sec. 25. Although the axis can not be broken by faults, -and that O:Qe particularly 

traced in the surface outcrops it parallels large northwestward-trending fault lies just 

approxin~ately the sync~ine that lies somewhat northeast of the crest of Twenty-five (Spellacy) 

to the south. _ . . Hill. They point out, in support of the idea 

• A s1nall anticline 1nay be traced in the out- of the existence of such a fault, (1) 'that southcrops from a poiiit near the middle of the west ·of the line along which this fault . is 

south line. of sec. 25 eastward to a point about supposed .to pass the oil sands are coarse 

a quarter of a 1nile south of the ·northeast grained and thick, but 1;10rtheast of it the sands 

corner· of sec. 36, east of which the' effect of are uniformly fine grained, thin, and ir:regular, 

. this s1nall fold. can not be recogn~zed at· the and (2) that the oil sands on opposite· sides of 

surface; but a s:niall topographic rise in the this line do not appear to be connected. · The 

109288°--19----9 . ' 
130 THE SUN$ET-MIDWAY OIL FIE;LD, 'c~IF.-PART I. 

true, explana~ion for these differences is that 

the· line maiks not the. position of a f~l.llt but 

the. positiqn of the nor~heaster:p. edge. of the 

area beneath wb.ich the A zone. is productive. 

Southwest ·.of this line· are the coarse-grained 

prod.ucing .sands of the A zone; north~ast of 

it ttre .the .. fine-grained sands ill the . stratigntphiGally lower B zone. . · 

· The presence of the deep sand that furnishes 

the oil. in ~he. J. M. S. and Californian Amalgamated properties in sec. 26 is also explained 

by a fault which, it is supposed, has dropped 

the main productive zone several hundred.feet. 

This hypothesis is clearly erroneous, for the 

main zon~ here is represented by tar sands 

which occur in quite their normal position and 

are ehcountered in. the upper parts of the wells 

of the J. M. S. and Californian Amalgamated 

.. companies. ·The sands from which these wells 

derive their oil is evidently a lens in the 

Maricopa shale. 

OIL SANDS. 

Position.:__The chief productive sands lie in 

the basal part of the McKittrick group mainly 

in the Etchegoin formation, although it, is pos:.. 

sible that in places the basal part of the Paso 

Robles ·formation may be productive. It is 

probable that near the crest of the anticline the 

uppermost part of the Maricopa shale is impregnated with oil and that the lower part of 

the main productive zone is· in this formation. 

Also in places· the coarse lenses in. the Maricopa 

shale ~re impregnated with oil, and ·such a lens 

yields the oil produced by the J. M.S. and Cali-

. fornia Amalgamated wells. 

Grain.-Part of the oil sands in the A zone 

·are co.arse grained, and in places they contain 

gravei and cobbles several inches in diameter. 

The B zone is finer~ grained, being particularly 

fine near the n9rthwest corner of sec. 25, where 

it is usually recorded in the well logs as shale. 

It is probable that the B zone is uniformly fine 

grained in the eastern part of sec. 25, although 

the greater production from it here suggests 

that it is coarser grained than it is in sees. 22 

and. 23. 

Zones.-In this area there are ·three main oil 

· zones-(1) the A zone, which is tP,eehief source 

of oil along the axial part of the anticline and 

ind~ed in all of this area except the northern 

and eastern parts of sec. 25 · and a smal.l area 

near the center of the W. ! sec. 26; (2) the B 

zone, which is separable from the A zone in the 

eastern edge of the area but which in the western par.t simply forms the lower portion of the 

thick productive zone; · (3) irregular lenses in 

the ~aricopa. shale. The position . of these· 

lens.es is not known except that of the one 

which yiel<;ls ~h~ oil in the J. M. S. and Californian Amalgamated , wells and which is here 

termed the J. M.S. ·sand. Its position is.shown · 

appr:oximately by the contour lines on Plate 

XXXVIII. 

A and B zones.-Fn the western part of the 

area the A zone is a thick succession of oil sands . . 

and tar sands with relatively sinall amou,nts of 

interstratified barren shale. In the NW. i 

sec. 26 the maximum thickness of this zone is 

500 feet. The upper part, probably the upper 

half, is usually either nonproductive or yields a 

very little heavy oil and is fu many of the well 

logs recorded as tar sand. In relatively fe~ of 

the wells is tl!e ca.Sing perforated {or this upper 

part of the zone,. but one or two of them that 

have been drilled less than 250 feet below the 

top of the A zone and therefore rely upon this 

part of the zone for their oil .have yielded as 

much as 400 barrels a day initially. In general, 

however, most of the oil is found in the lower 

half of the· A zone. 

In the eastern part of se~ 26 the A zone has 

a maximum thickness of a little more than 400 

feet near the crest of the anticline. Many of 

the wells have been drilled less than 150 feet. 

below the top of the A zone, and these wells . 

have yielded a very fair production. In the 

northeast corner of sec. 26 the A zone' commences to thin out, and the upper part prob-· 

ably contains edge water. Certainly the uppermost part is.much less productive than it is 

somewhat closer to the axis of the anticline, 

and the zone itself is composed more largely of 

barren shale. This area is really part of what 

is here called the "transition belt" lying between the:area which is dependent upon the A 

zone for its oil and that which is dependent 

upon the B zone. In the SW. i sec. 26 the A 

zone seen1s to be slightly thinner than it is near 

the axis of the anticline, the average thickness 

drilled . through being about 200 feet, and to 

judge from the information afforded by the few 

deep wells here most of the wells seem to have 

been drilled almost if not quite to the bottom 

of the productive zone. 

The productive zone in the SW. i sec. 25 lies 

entirely within the A zone, which has a maxi-

·mum thickness here of about 400 feet and is 

appa-rently of much the same character as in 
DUNLOP-SECTION TWENTY-FIVE AREA. 131 

the SE·. t sec. 26: However, just north. and hav.e been drilled with only a single~string of 

east of this locality, in the west-central part of casing and have had no water trouble. 

sec .. 25, .the A zone begins to ·fray ·out into ·a In the E. ! sec; 26 water sands are scattered 

number of individual sands separated by. barren through the tar sands· that rest upon the A 

strata. The boundary of the belt in which the·A zone. The recm;ds of these water sands are 

zone splits up may be outlined roughly on the rather discordant, and no single sand ·or thin· 

west by the 400-foot contour on the top of the A zone seems to persist throughout the area. 

zone (Pl. III) and on the east hyaline drawn from Some water is· reported as close t\8 50 feet to 

the northwest corner of sec. 25 to the middle of the top of the A zone. 

the east border of that section and thence' to a Edge water.-In a belt occupying the central 

point near the middle of the SE. t.· East of part.of ~ec. ~5 and bounded approximately on 

this line the productive sands are· in the B zone, the west by the 400-foot contour on the A 

and although the A zone contains· some oil· zone and .o~ the e~t by the s.ea-lev~l contour on 

farther east, especially along the B..xial.part of that same zone, the upper part of the A zone is 

the anticline in the central part of sec. 30, it occ~pi~d by true· edge water/ the productive 

has nowhere yielded oil in commercial amounts .. sands here being limited to the lower pf.U"t of 

The B zone is apparently about 100 to 200 feet the A zone and to. the· underlying B zone. 

thick and seems to pe closely underlain by This edge water hi,lS proved especi~y. troublewater. · some, for many of the wells have been cased off 

J. M. S. sand.-The J. M. S. sand, from above it and others below it, and in consewhich the wells of the J. M. S. and. Californian quence the upper part of the productive zone 

Amalgamated companies . derive their oil near here is flooded. yY ater sands in this position 

the center of theW. ! sec. 26, is a sandy lens in have given more trouble than any other water 

the Maricopa shale: This lens has a ·small sands on Spellacy (Twenty-five) Hill, being 

areal extent and is probably pretty well out- even more troublesome than the bottom water 

lined by the wells·alrcady drilled. Its top lies which has been encounte;red in one or two of 

about 600 to 800 feet below the top of the A the wells. . 

zone, and its thickness is reported as from 100 Bottom water.~In the northeaster11. part of 

to 200 feet in the wells that have entered it. sec. 26 and the northwestern part of sec. 25 the 

The approximate position of the top of this same conditions exist as prevail in the SW. t 

sand is shown by the sketch contour· lines on sec. 23 and the central part of sec. 22-,---that is, 

Plate XXXVIII. · the A zone is closely underlain by ·a persistent 

The sand seems to have a somewhat greater water sarrd. 2 The approximate position of the 

·dip than is shown by the sands of the overlying top of this ·water sand is indicated on Plate . 

A zone. This · difference ,. may be. truly a XXXVIII. . 

structural feature· and repre~ent the difference In the northern part of sec. 26, along a line 

in the amount to which the Etchegoin forma- drawn from northwest to southeast through 

tion and the M~icopa shale are tilted, but the center of the north line of that section, this 

1nore probably it simply shows the shape of the water sand lies between 350 and 400· feet below 

sandy lens 'that contains the oil. It· is probable the top of the A zone, but northeastward from 

that other sandy lenses in· the Maricopa shale this line t]le distance between the two gradually 

are impregnated with oil in various parts of the increases. Southwestward from this lirie water 

area, particularly along the· ·axial part of the ·sands do not· so closely underlie the A zone, 

anticline. · Their position can.not be predicted and those sands which have been encountered 

in advance of drilling from conditions shown in the deep wells .seem to occur well within the 

by other de~p wells drille4 along the foothills. Maricopa shale. Such deep water sands have 

WATER SANDS. 

Top water.-In the NW. ·l and probably 8lso 

in most of the SW. t sec. 26 top water is either 

absent or else present in so small amounts as to 

be negligible. Many of the wells here, espe~ 

cially those along the axial part of the anticline, 

·been encountered between the· bottom of the 

A zone and the top of the J. M. S. sand, the 

water· there being under considerable pressure. 

The chief water which is found closely below 

the A zone in the northern part of the section 

1 See analysis 16,. Table 14, Part II (Prof. Paper 117). . 

s For analyses see Tables 2_5 and 26, Part II (Prof. Paper 117). 
132 THE SUNSET-MIDWAY OIL .FIELD~ CALIF.-PART I. 

may be regarded as edge water in the B zone, 

·similar to that in sees. 22 and 23-that is, edge 

water which is working into the B zone from the 

west. (See sketch, fig. 14, f?howing conditions 

in sec. 22, p. 126.) 

BEDS ABOVE THE PRODUCTIVE ZONE. 

In practically all of sec. 26 tar sands occur 

:scattered through the atrata above .the A zone, 

;almost if not quite to the surface. They reach 

·the surface 01 within a very few feet of it in the 

northeast corner of the· section; whereas in the 

SE. l they are about 600 feet. thick- and their 

top reaches within 300 feet. of the surface. A 

separation between the A zone and the over-

· lying ta.r sands ip. the NW. ! sec. 26 is very 

la:rgely a· matter of personal observation, and 

what is recognized ·as the -top of the productive 

zone by one driller i,., not at all certain to be 

recognized by another driller who puts down a 

well only a few hundred feet distant. The tar 

sands in this section are .somewhat thicker and 

are said to be somewhat more filled with tar 

than are those in sec. 22. 

CHARACTER OF THE OIL. 

A zone.-In sec. 26 the A zone· frunishes an 

·oil of rather uniform grade that rang'es in gravity from 12.5°~to 15° Baume and averages 146 • 

In any part .of the area the heaviest oil from 

this zone is found in the uppermost sands. 

The gravity of the oil, however, shows a slight 

. variation with the position in the area from 

which it is obtained, the oil close to the outcrop 

being somewhat heavier than that farthm from 

it. The southernmost· wella drilled yield oil 

of about 12.5° Baume. 

The· variation in gravity shown by the oil 

frorri different wells in this area is caused.for the 

inost part by one or. both of the following reasons: (1) All. the wells are not perforated for 

the same part of the productive zone; some· 

produce from the uppermost heavy oil san<h, 

and others are perforated only for the lower 

part of the zone, these upper sands being regarded as tar sands .. (2) Some of the wells 

produce a· considerable amount of water,· derived either from water sands they have penetrated themselves or from oil sands that have 

been flooded by water from adjacent wells. 

Such "wet" wells invariably yield heavier oil 

than· wells drilled uncler similar conditions and 

. yielding ~o wate,r. 

In sec. 25 ~he character of. the oil is about the 

same as that described for sec. 26 except in the 

northern and eastern parts of the section, where 

the oil is produced· both from the A zone and 

from the underlying B zone. The 400-foot 

contour on. the A zone may be considered as, 

marking approximately th~ eastern limit of the 

area from which oil is produced only from the 

A zone. 

B zone.-In the northern and eastern parts 

of sec. 25-that is, the area bounded approximately on the south and west by the 400-foot 

contour on the A zon~-oil is 'produced from 

both the A zone and the B zone.' The B zone 

yields the entire p~oduction .in the northeast 

corner of the section, just outside the m-ea here 

described, and also in several wells between 

that corner and the 31:00-foot contour line mentioned; The oil produced in this area ranges 

in gravity from 16° to 20° Baume. It is probable that .the oil in the B zone itself has a 

gravity of approximately 20° Baume and that 

the heavier grades produced are mixtures of 

this oil with that from.the A zone. 

J. M.S. sand.-The stray sand in the Maricopa shale which yields the oil produced in the 

Californian Amalgamated and J. M. S. properties furnishes oil that ranges in gravity from 

13.5° to 14.5° Baume. Other lenses in the 

Maricopa shale would probably furnish oil of 

similar character. 

PRODUCTION. 

A and B zones.--'-The initial production of 

many of the wells that produce from the A 

zone in the western part of the area-that is, 

in the part lying west of th~ line marked ap,.. 

proximately by the 400-foo~ contour ori the 

A zone-was· more than 150 barrels daily and 

in two wells was reported to be as great as 500 

barrels daily .. ·The area is somewhat spotted, 

and a few wells never produced more than a 

very few barrels daily. However, these "dry" 

well-; are few, and if they ·are disregarded the 

average initial production was probably between 100 and 125 barrels daily. In 1914 the 

average production for the wells was about 40 

barrels daily. 

In the eastern part of the area~that is, the 

part bounded on the west by the 400-foot contour on the top of the A zone-the initial production was about the same as ·in the western 

part, but in 1914 the rate was between 50 and 

60 baiTels a day. · 
AREA EAST OF TWENTY ..:FIVE HILL. 133 

A considerable number of wells flowed. originally, but all were soon reduced to pumping. 

In places. where the sand has become flooded 

with water air lifts are used, and several thous.and ban-els of water is lifted daily. ·Although 

usually only a few barrels. of oil is recovered 

from the wells in which the air lift is placed, 

the water is s.o reduced in the surrounding area 

that wells which oth~rwise produce only water 

become fairly good producers. of oil. 

J. M. S. said.-The production from the 

lenses in the Maricopa shale in the wes t-een tral 

part of s.ec. 26 has been irregular. Some of 

'the wells were reported to have an initial pro~ 

duction of about 350 barrels daily. The aver-

•age daily yi'eld of the wells producing in 19~4 

was 40 barrela or less.. 

SUGGESTIONS FOI~ FUTURE WORK. 

This area is about . the most completely 

drilled part of the Midway field. Future drilling will be concerned chiefly in developing the 

A and B zones in the few remaining locations, 

for the whole of the productive zone in the 

McKittrick group has be€m prospected thoroughly and JI\OSt of the wells would be benefited but little by being deepened. The chief 

trouble here is concerned with the water that 

has been allowed' to enter the producing sand 

owing to faulty handling of both top and 

bottom water. 

In .sec. 26 water troubles are of three types. 

(1) A few wells in the northeast corner of the 

section have entered the water sand that lies 

below the A zone. So far as the whole area is 1 concerned, however, the bottom water could 

doubtless be handled by plugging the few deep 

wells that have entered this water sand. The 

sand is a persistent one apd is traceable toward· 

the northwest some distance into sec. 22. (2) 

A few of the wells in theSE. i have e.ncountered top water. As the water sand is thin, 

however, and is usually sepfi:rated from the 

productive zone by a considerable thicklless of 

barren strata, and as the water in it is u~ually 

under low pressure, it is easily cased off. (3) 

The group of wells in the center of the W. t 

which derive their oil from a lens in the Maricopa shale pass before entering the productive 

oil lens through water sands. ·that lie in the 

upper part of the Maricopa shale, and as. this 

water has not everywhere been s.hut off prop-

~ith edge water in the top of the A zone and. 

that conderned with bottom water. Too ·water· 

or· edge water are probably the more trouble-· 

some and are especially prominent in the central'. 

part 9f sec. 25, in the "transition belt." The 

top of the A zone is not very productive anywhere in this area, is occupied by water in 

many phices, and has been cas.ed off with the 

overlying barren strata· in some wells and, with 

the productive zone in ·neighboring wells. 

Were the a.rea to be drilled now for the first 

time it·would probably be wise to case off both 

above and below this part of the A ZO!le, .but 

as the area is. now so thoroughly drilled and the~ 

normal relations of oil and water have been so· 

greatly changed, the present handling of the·· 

wells now must be determined by an intimate· 

study of the his. tory of all the wells. in the, 

immediate vicinity, it being borne in mind that .. , 

this. top part of the A zone is occupied in places. 

by water and that water which originally came·. 

from this sand is causing most of the trouble in 

this part of the hill. Bott?m water, which ha.s: 

been encountered in one or two of the wells, is· 

probably not very troublesome except in the 

northwest corner of the section. The approximate position of the bottom water is shown by 

the sketqh contour on J;>late L~VIII. 

AREA EAST OF TWENTY-FIVE HILL. 

[Southeast corner of sec. 12, ·east edge of sec. 13, east edge. 

of sec. 24; northeast corner of sec. 25, T. 32 S., R. 23 E.;: 

·southwest corner of sec. ·17, all hut northeast corner of.' 

sec. 18, sees.' 19 and 20, S. ~ sees. 21 and 22, sees. 26 to· 

30, inclusive, N. ~ sees. 31 to 35, inclusiv~, T. 32 S.,.. 

R. 24 E.] 

LOCATION AND OPERATORS. 

The area. embracing the ·foothills east of 

Twenty-five Hill extends from the town of Taft 

southward about half~ay to :Maricopa along the 

west side of Midway Valley. The companies . 

operating here .in 1916 or controlling lands· on 

which wells had been drille<;l prior to that time 

were the Standard, Kern Trading & Oil,. 

Chanslor-Canfield Midway Oil, Section Twenty-· 

five, American Oilfields, Edmunds Midway,. 

Knickerbocker, General Petroleum, Baltimore~. 

Petroleum Syndicate, Pyramid, Union, Lakeview No.2, and Manitoba Crude. 

GEOLOGY. 

erly it has flooded s.ome of the wells. This. area. lies on the east end of the Spellacy 

In sec. 25 there are water troubles of two anticline, which here plunges. eastward at an. 

types-that concerned with the top water or angle of about ·6°. The fold is here broad and 

.' 
' 

. '134 THE SUNSET-MIDWAY OIL FIELD, .CALIF.-PART I. 

fairly symmetric, and .although it can not be 

traced with any great degree of precision in the 

beds that crop out, its position _is fairly well 

indicated by the position of the rolling hills; 

for·the fold does not extend much beyond their 

edge. The oil sands . are apparently .folded 

somewhat more sharply than the surface beds, 

and the structure may be interpreted readily 

from· the logs of the wells. , 

Although the Spellacy anticline is broad 

and symmetric, the syncline· that separates the 

anticline ·from the main range is· very· asymmetric, the ·dip on the south flank being very 

.steep in contrast to the moderate dip on the 

north flank-that is, the dip on the south flank 

of the Spellacy anticline. Indeed, the bending 

-is so sharp that the beds may possibly be fractured along the line marked by the· axis of the 

syncline. ·It· is difficult to correlate the oil 

sands here, and although no regulardifferencein 

c their elevation could be made out it is possible 

that the irregularity is caused by -faulting. 

OIL SANDS. 

producmg sands li~ below the top of .the B zone 

and it isfrom sands in the upper part of that 

zone that the wells in sec. 28 derive-their. oil. 

The C zone is contoured on Plate III only for 

the northern edge of" this area. In the ~entral . 

and southern parts the uppermost sands containing commercial ~mounts of oil are clearly 

in th~ B zone·, and although most of the large 

wells have derived their oil from beds 250 feet or 

so below .the top of the B ~one, still most of the 

w~ll.s depend upon the uppermcft portion of the 

B ~one for at least part of their oil. It would 

be' possible in much of this "area to contour 

separately the sand from which the big flowing 

wells derive their ov, but it is not thought desirable to do so, as the sand lies at a fairly constant distance of about 250 fe~t below the top 

of the B zone, and its position may be calculated if the position ofthe top of the B zone is 

known. Contouring the C zone throughout 

this area would overload the map. 

WATER SANpS .. 

. Top water.-Top ;water occurs fairly clos-e 

The. oil~sands in this area lie entirely in the to the top of the. B zone in much of the area, 

Etch ego in formation. Several of the wells have being recorded as about 100 feet· or .so above 

been drilled deep enough to enter the underly- the top. of the B zone in· man·y wells both on 

ing Maricopa shale, but the records of these. wells .the north flank· and particularly near the 

do not give enough information to perrit an eastern -edge of the fold in sec. 28.. Many 

accurate determ.ii:mtion of the position of the other water sands are ·recorded as occurring 

top of the shale. It is probable, however, that in the upper part of the section, but this 

the chief producing sands-that is; tho~e which lowest top~water_ sand is the· really important 

lie about 250 feet below the top of the B zone one, for the. water string must' be set below it. 

and from which the flowing wells in sec. 3.0 have In the very .western edge of the area, near 

. _4erived their oil-are almost if not quite at the the axis of the anticline, beds 400 feet above 

base of the Etchegoin. It is r~ported, however, the top of the B zone contain some heavy oil. 

that near the east edge of .sec. 30 fossils ·pre- This is the top of the A zone that· is productive 

sumably indicative of the Etchegoin formation in the area to the west. The water just men~ 

have been found 1,000 fe~t below the top of the tioned tis properly to be considered as edge 

B zone.. · · water in the A zone.· The area here considered 

· The oil sands in the Etchegoin formation ·in is so far down the plunge of the anticline that 

this area extend through a stratigraphic thick-. the A zone along the crest of Twenty-five Hill 

ness of at least 900 feet. No one well,. however, is. in no danger of flooding if in the area under. 

reports commercial oil sands throughout so discu~sion all top water is shut off just above 

great a thickness of peds, for the beds tha_t form the top of the B zone~ . 

the uppermost part of the productive zone m' Bottom water.-In the north end of the arE<a~ 

the western part. of sec. 30 do not contain oil in east of. Taft, bottom :water lies f!,bout 100 to 

the eastern part of the area. 150 feet below the top of the C zone.1 

Near .the west edge of sec. 30 the uppermost One .or two wells in tl;te western edge of the 

beds containing commerc-ial amounts.of oil lie area near the crest. of the anticline. report 

some 400 feet above the top of the B zone. water approximately 250 to 300 fe~t pelow 

These beds are the equivalent of the A zone, the top of the B zone-that is; at about the 

which yields the oil in the central part of sec .. 25, same distanc~ below the ~op of the. B zone as 

T. 32 S., R. 23 E. ·In most of the area ·the · · 1 See analyses in Tables 23 and 25, Part II (Prof. Paper 117). 
' 

AREA EAST OF' TWENTY-FIVE HILL. 135 

the sands which have· yielded the big flows 

of oil in the central part of sec~. 30. · The 

difference in the succession of the beds pene'" 

tra ted by wells in the two parts of this section 

is striking. ·This difference is probably to. be 

explained by the faQt .that in the center of 

sec. 30 the producing sands lie at the base 

of the Etchegoin formation, but that farther 

west these sands are wedged out along the 

unconformity and that water sands occupy 

either the beds of the Etchegoin or beds in 

the upper part' of the Maricopa shale near the· 

western edge of sec. 30. 

Down the plunge of the fold water· is 

reported about 100 'feet below the top of 

the B zone both along the axial . part of the 

anticline and in its north fl.ank. 1 This water 

is apparently edge water in the B zone, for 

it lies above the horizon from which the 

flowing wells in the center of sec. 30 have 

derived their oil. It· is probable that other 

oil sands lie below this water sand, although 

the singie well that has been drilled· in the 

east end of the area f~r ·any great distance 

below the water sand has not found commer-

. cial oil sands at greater depth. 

BEDS ABOVE T~E PRO:J?UCTIVE ZONE .. 

·The beds above the B zone contain a great 

number of tar and water sands. There.seems 

to be no· regularity in the occurrence of·, these 

sands other than the fact that along the crest 

of the anticline they constitute a zone about 

200 feet thick that lies about 700 or. 800 feet 

below the surface. This tar .zone appears to 

have a constant.relation to the surface rather 

than to the underlying oil sands~ 

BEDS BELOW THE PRODUCTIVE ZONE. 

~everal wells have been drilled completely 

through the productive zone and· have pEmetrated the underlying Maricopa ·shale. No one 

of these wells, however, affords sufficient data 

to indicate the exact position of the contact 

between the shale and;the overlying Etchegoin 

formation. The lower beds penetrated by these 

wells are usually recorded as consisting largeJy 

of sandy shale or sand, the beds resembling 

much those penetrated by the deep wells in 

the western part of sec. 24, T. 32. S., R. 23 E. 

None of these wells has encountered commercial amounts of oil in the shale. 

1 Sco analysis 49, '!'able 23, l~art II (Prof. Paper 117). 

PRODUCTION. 

The production of the well~ in this area 

varies greatly. · The best wells are those of 

the Standard Oil Co. in the center of sec. 30, . " 

a few of which produced several thousand 

barrels daily when they were :first brought in. 

Wells of the same company in the center of 

sec. 20 and the Edmunds Midway No. 1, in 

sec. 32, hav·e likewise yielded large amounts of 

oiL The area is somewhat spotted, however, 

and many of the wells have never produced 

more than 50 or ·60 barrels-some no more 

than 20 barrels-a day. The variation in 

production seems. to be c·aused by three chief 

factors-the position of the well with relation 

to the anticline, the relation of the oil sands 

it taps. to the unconformity, and the lenticular 

character of the beds, the l,arge w~lls usually 

being located along the axial part of the fold 

and the sands that yield the oil usually lying 

in the lower part of the "Etchegoin !ormation 

close to the underlying diatomaceous Maricopa 

shale. . · 

CHARACTER OF THE OIL. 

The oil obtained ranges from about 15° to 

26° Baume, but most of it runs about 20°. 

The deeper sands of the C zone do not ·appear 

to contain lighter oil than the sands in the 

upper part of the B zone, but there appears to 

be a variation in the gravity of the oil within 

a given sand according to its position in the 

area, for the B zone contains lighter oil in 

the eastern part of the area than in the wesir. 

ern part, where it is not buried so deeply. 

SUGGESTIONS FOR l<'UTURE WORK. 

In all 'the area except possibly th~ north 

end,. which lies near the axis· of the Midway 

Valley syncline, and also the east end beyond 

the area where the B zone is con toured· on 

Plate III, the B z~ne contains productive oil 

sands. In most of the area, however, the 

deeper oil sands usually contain more oil than 

the sands in the upper· par~ of the B zone, and· 

all the large flowing wells along the axial part 

of ·the· anticline have derived their oil from 

sands 250 feet or ·so below the top of the B 

zone. West ofthe center of sec. 30, however, 

these deeper sands are wedged out along the 

unconformity at the base of the Etchegoin 

formation, and in that part of the area it is 

only from. the upper par.t of the B zone that 

• 
136 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

oil should be expected. It is prohable that 

farther down the .plunge and down the north 

flank of the anticline· than the edge of the· 

area iri which the B zone is c~ntoured on 

Plate III-that is, where the top of the B 

zone lies more than 2,500 feet below sea levelmuch of the upper part of the B zone, posto that date. were the Midway Oil, Canadian 

Crude, August, ~anh.attan Midway, American 

Oil:fields, Kern Trading & Oil, Union, Lakevie.w No. 2, .Ethel D, Maricopa National, and 

General Petroleum. 

GEOLOGY. 

sibly all of it, is occupied by water. ·If pro- . This area embraces the west end of the 

ducing sands occur in this part of the district . Thirty-five anticline, extending from the axiS 

they lie below the top of the. C. zone-'that is, of the Phoenix syr1cline on the south to . the 

more than 250 feet below the top of the B axis of the sharp syncline on the north which 

zone. Wells drilled in sec. 28 have produced separates the Thirty-five and Spellacy antionly from the top of the B zone, having stopped clines. In this part of the area the Thirty~ 

when a persistent . water sand that occurs five anticline plunges eastward at an angle of 

there wasreached. It is probable that other about 6°. The axial part of the anticlineproducing oil sands lie belo.w this water sand, that is, the belt in which. the beds have a 

and although one well has been drilled below fairly low dip-is rather more narrow than 

it and has not encountered oil, further testing the axial part of. the Spellacy anticline, for it 

for deeper sands in this part of the area is is barely half a mile across. Both the north 

justified.. However, deep wells west of the and south edges of the axial part of the an~icline 

center of sec. 30 can :bope to obtain oil below ai;e fairly well outlined, for the dip of the beds 

the B zone only from lenses i.n the. diatoma- increases rather abruptly and on the north 

ceous shale. ' ' . · · flank of the fold the oil sands dip at ·angles of 

In this area many wells have been sunk into 20° to 30°. The Thirty-five anticline is not 

the underlying Maricopa shale, but none_ of quite symmetric, for ·the Phoenix syncline , 

them has found producing oil sands in it. is much shallower than the syncline on the 

The anticline ~ere is a strong, well-marked north. The Thirty-five anticline does not 

fold and would appear to be as good a struc~ extEilnd we~tward beyond the west edge of the 

tural feature as one could hope to find for the area here described, but as is shown on the 

accumulation of oil. The fact that many of map of the field (Pl. III), the Phoe1;1ix _syncline 

the wells that have entered the shale ]}ave and the Thirty-five anticline gradually apnot found oil sands in it is a good illustration proach each other and die out on ·"the north 

·of the risk attending drilling for lenses in the flank of the California Fortune anticline. The 

shale. steeply dipping beds in fractional sec. 27 are 

SAGE-LAKEVIEW AREA. to be considered as forming the north.· flank 

· [S. ! sees. 31 to 34, inclusive, southwest comer of .5sec. 3, 

' T. 32 S., R. 24·E.; fractional sees~ 25 and 26, eastern 

part of se~. 27, northeast comer of sec. 34, all but southwest comer of sec. 35, sec. 36, T. 12 N., R. 24 W.; sec. 

30, western part of sec. 31, T. 12 N., R. 23 W.; northwest comer of sec. 6, T. 11 N., R. 23 W.; north edge of 

sec.1, T.ll N., R. 24 W.]. · 

LOCATION AND OPERATORS. 

The Sage-Lakeview area embraces the group 

of hills that lies just north of Maricopa, ex.tending from the ()utskirts of that town northward 

to the north edge of the alluvial flat at the 

mouth of the large gulch that trends eastward 

past the old Augus't water wells, in sec. 31, 

T. 32 S., R. 23 E. (See geologic section, Pl. 

XXVII, and. map, Pl. XLIII.) The companies operating here in 1916 or clai:niing 

land upon which wells ha~ been drilled prior 

of the California Fortune anticline rather 

than 'the north flank of the Thirty-five anti.:. 

cline. 

OIL SANDS. 

\ 

The position of the oil sands is shown rather 

better in this part of the field than in most 

other parts. They lie -in the lower part of 

the Etchegoin formation, and the sands which 

have yielded great quantities of oil in such 

wells as La~eview No. 1 are practically· at 

the base of this formation. Not all the flowing 

wells, however, have produced oil from sands 

at .th-e base of the formation, for several wells 

nearthenorthline of sec. 36,·T. 12 N., R. 24 W., 

have obtained their oil from· sands at the. top 

of the B zone, fully 400 feet above the base 

of the· Etchegoin. On account of the uncon-
SAGE-LAKEVIEW AREA. 137 

for1nity between the Etchegoin and the under- wATER SANDS. 

lying. :Maricopa shale these sands are wedged Top water.-In the S. t seo. 36, T. 12 N., R. 

out and do not underlie the western part of 24 W., .in the area in which the· A zone is con- · 

the area along the axis of the Thirty-five anti- toured, watl3r sands lie very close above the top 

cline. The approximate position of the top of of the A zone,· having been encountered in 

· the shale is shown in the geologic section (Pl. many of the wells less than 100·, feet and in 

XXVII) and on the maps (Pl. XLIII and fig. 15) · some places less than 50 feet above the top of 

The productive sands may be divided into that zone. In many of the wells part of the A 

two groups-those in the Etchegoin and those zone has been oased ·off with th~ overlying 

in the underlying Maricopa shale. water sands; for the sands in the upper part 9f 

The total thickness of the oil sands in the the A zone in most· of the area contain a very 

Etche(J'oin formation is about 1,000 feet. No heavy oil, but water is not reported to·occur 

single ~ell, hm~ever, has penetrated oil-bearing below the top of the A zone in any well in the 

beds of this thickness, for on accou.p.t of the area where the top of this zone is contoured on. 

unconformity at the base of the Etchegoin the Plate III. 

. deepest sands in the Etchegoin in the easte~n Edge water.-On the flanks of the Thirtypart of the m·ea, in sec. 31, are not present Ill five anticline the A zo~1e is occupied by water. 

·the western part; also the uppermost sands The separation between the area in which the 

which are productive in the western part of the sands in this zone contain oil and that in which 

area are dry or are occupied by :water ill the th~y contain water is fairly sharp and is marked 

eastern par~. , · . by the· line separating the axial part of the 

The productive oil sands in the Etchegoin anticline, where the beds have a moderate dip, 

are here divided into t'\vo parts, which are· from the flank of the ~old, where the beds are 

described as the A and B zones. The A zone is more steeply tilted~ The logs of almost all the 

productive in tho western part of the area along wells that have been drilled on the flank of the 

the crest of tho Thirty-five anticline, but the . fold report water down almost to the top of 

area in which this sand yields oil is limited the B zone, some of them recording sands that. 

rather closely to the aXial part of the fo~d, and lie less than 100 feet .above the top of the B 

sall.ds in this zone have not yielded oil in any ~one as contaW:ing water under considerable 

considerable amounts outside of the area in pressure. · Water from these sands is clearly 

which the top of this zone is contoured on edge water in the A zone, aJ?,d as the oil is exPlate III. The top of this sand lies between hausted from t4at· zone along the crest of the 

300 and 400 feet above- the top of the B zone. anticline water will work its way up the dip 

Tho B zone has its maximum thickness in and appear ·in the wells n:ear the axis of ·the 

tho eastern part of t)le area. In the. north- fold. There has been no regularity in t~e 

eastern part of sec. 31 it is about 700 feet thick handling ~f the wells on the north flank of the 

and is compose~ of alterJ?,ating oil and water fold, particularly those along the line between 

sands, like the productive zone in sec. 32, T. 12 seos. 35 and 36, some of the wells there having 

N., R. 23 W.-in fact, the description of the produced from the upper sands and some from 

zone in thatseotion (pp.140-142) applies equally the lower. In ccmsequence water has been 

well to the eastern part of sec. 31. The big very troublesome in this part of the area. 

water sand which lies 400 feet or so. helow the Bottom water.-In most of the western part 

top of the B zone in sec. 32 continues west- of the area water occupies the upper part of the 

ward into sec. 31, and its approximate position :Maricopa shale, and wells that have entered 

is shown on Plate XLIII. that shale have found water sands at differIn the SW.i sec. 36 the chief oil sands lie in ent pos~tions below the top of the :a zone. 

the A zone, and the B zone ·is not more than The distance these water sands lie below the 

100 feet thick,for'the top of the diatomaceous top pf the B zone is of course dependent upon 

shale is only that far below the top of the B the thickness of the Etchegoin formation. In 

zone. Most of the wells iii this area depend order to understand the relation of the bottom 

on the A zone for their oil, although the big water to· the producing oil sands one must 

wells have derived most 9f their· oil from the thoroughly understand· the signifi~ance of the. 

relatively thin B zone. unconformity, for it is i,mpossible to correlate 
138 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

oil sands simply on the basis of· the. distance 

they lie below the B zone. For example, 

Lakeview well No. 1 derived most of its oil 

from sands· that lie between 250 and· 300 feet 

below the top of the B· zone. Wells drilled 

only a few hundred feet south and west of this 

fold, however, have not found· this producing 

oil sand but have encountered heavy flows of 

water _in sands that lie· at approximately the 

same distance below the top of the B zone as 

the sand from which Lakeview No .. 1 derived 

The water sands encountered in certain 

wells in the eastern part ~f the area-as, for 

example, in South Midway well No. 23, Union 

wells Nos. 2, 8, and .14, and a few of the Ke~n 

Trading & Oil Co.'s wells in sec. 31-are clearly 

in the ·Etchegoin formation and are comparable · 

with the sands ·described in. some detail in the 

part of this rep·ort dealing with sec. 32, T. 12.N.·, 

R. 23 W. (pp. 140-145). 

PRODUCTION. 

its oil. The explanation for this discrepancy More than 20 wells in this area have had an 

is that the producing sands of the Lakeview initial production of over 1,000 barrels a day, 

No. 1 well are ·wedged out along the uncon- and at least an equal number an initial proformity, and that west of that well water sands duction between 400 and i,OOO barrels daily. 

occupy the uppermost part of the Maricopa · The largest well in the whole Midway-Sunset 

shale ~r the base of the_ Etchegoin formation. district,· Lakeview No. 1 (see Pls. XL; XLI, .0; 

27 

34 

T.l2 N., R.24W. 

FIGURE 15.~Sketch map showing approximate position of the top of the 'Maricopa shale. in the western part of the Sunset field. 

The August water wells, in the southeast 

corner of sec. 31, T. 32 S., R. 24 E., derive their 

water .

1 from sands well down in the Maricopa 

~hale. So likewise does ·well F. of the Sunset 

Monarch Oil Co~/ in sec. 26·; wells D and I of 

the same company; and Sage ·wells 11, 15, 8, 

16, 17, and 19 in sec . .35.2 The approximate 

position .of the top of the M:aricopa shale in the 

eastern part ofT. 12 N., R. 24 W., is shown on 

the .accompanying ·sketch map (fig. 15). This 

map is not very accurate, for the dat~ upon 

which it is based are meager, but it serves to 

indicate roughly the base of the zone in which. 

the producing oil sands occur in the Etchegoin 

formation and therefore tlie depth belQW which 

drilling should not be continued -unless it is desired to prospect for lenses in the diatomaceous 

shale. · . 

1 For ~nalysis see Table 16, Part II (Prof. Paper 117). 

2 See analyses 69 and 70, Table 26, and analysis 15, Table i.6, Part II 

(Prof. Paper 117). 

XLII, A), is iri the cente~ of' t4e area; well 

down ·ori the north flank of the Thirty-five 

anticline.· This well is said. to have produced 

as much as ·65,000 barrels a day and is 'credited 

with having produced in all more than 8,000,000 

barrels of oil. It derived its oil from a sand 

which lies· about 300 feet b~low the top of the 

B zone. Furthe~ data' regarding this well are 

given in the part of the report dealing with the 

history of development (p. 65). 

Many of the large flowing wells in this are11 

(see Pl. XLI, 0), particularly those near the 

riorth line of the NE. l sec. 36, have derived 

their oil from sands which lie no deeper than 

150 feet below the top of the B zone. 

The location of the large flowing wells with 

relation to the s true ture is of interest, for the 

wells are not near the axis of the fold but well 

down its north flank. The factors controlling 

the location of the highly productive sands are 

clearly the folding of the·beds and the relation 
U. S. GEOLOGICAL SURVEY 

A. FLOWING WELL BEING BROUGHT IN, SUNSET OIL 

FIELD. 

Well No. 30 of Ethel D. Oil Co. This well was soon controlled and 

flowed a few hundred b arrels daily. 

PROFESSIONAL PAPER 116 PLATE XLI 

B. LAKEVIEW NO.2 GUSHER, MAY, 1914. 

This photograph was taken a few days after the well had come in. 

Photograph by G. S. Rogers. 

G. LAKEVIEW NO. 1 GUSHER, OCTOBER 2, 1910. 

This photograph was taken after the derrick had been removed and the well surrounded by a dam of sacks filled with earth. Photograph by 

W. C. Mendenhall. 
U. S . GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XLII 

A. WELL NO. l OF LAKEVIEW OIL CO. NO. 2. 

Well at right,. This photograph was taken the day the well came in. Note the height of the derricks used in this part of the field. 

B. SOUTHEAST END OF PLUNGING' FOLD IN BUENA VISTA HILLS. 

This fold is iu the northeast corner of sec. 36, T. 31 S., R. 23 E. Well No. 24 of the Standard Oil Co. (McNee lease) is shown almost on the 

axis of this fold. The plunge of the fold is well shown by the white calcareous bed. 
SAGE-LAKEVIEW AREA. 139 

they bear to the . unconformity.· The highly 

productive sands near the north line of sec. 36 

are wedged out along the ·unconformity and do 

not occur in the crest of -the Thirty-five anticline, near the center of 'the· W. !'sec. 36. An 

inspection of the figure showing the relation of 

the big wells. to the structure (fig. 6) will show 

that in the Sunset field· the big wells in Maricopa Flat, sec. 35, T. 12 N., -R. 23 W., near the 

east end of the Thirty-fi:ve anticline, are near 

the crest of the anticline. · Toward the. west 

the big wells are situated along- a line which 

departs gradually from the line marking the 

axis of the fold, and near the west end of'the 

fold they are some distance down the north 

flank. The position of the large wells is of 

· course controlled in part by the location of the 

early wells, for the first wells, other things 

being equal, get the flush. production, but. it is 

in very large part determined by the position of 

the productive sand in the Etchegoin formation, which is wedged out against the unconformity farther south ·and west. 

CHARACTER Ol!~ THE OIL. 

ducing sands in the B zone lie not .more than 100. 

feet below the top of that zone. Inasmuch as 

water lies so close to the top of the Maricopa. 

shale care must be exercised in drilling for 

sands in· the lower part of the B zone not to 

enter the shale. Figure 15 indicates· approximately the base of the Etchegoin formatio~--:­

that is, the horizon which marks the base of 

the zone containing the chief productive oil 

sands. 

A great many wells liave.been drilled into the 

underlYing ¥aricopa . shale and have found 

some oil in sandy lenses in it. So far· these 

wells' have not yielded any great quantity of oil, 

and it will l?e wise before prospecting for these 

deep. sands to drain thoroughly the sands in 

the Etchegoin formation. 

Drillers in· this area have not followed any 

uniform practice in handling the various oil 

sands, and a great deal of water trouble. may 

be ascribed to this lack of uniformity. It is 

very unfortunate that this part of the area 

shoUld. be divided into so many small holdings, 

for under such conditions it is almost' impossible to regulate the drilling properly. 

The oil derived from the A zone ranges in T~e chief geologic features which must. be 

gravity from 14° to about 17° Baulll:e. The B · underStood before any rational policy can be 

zone yields oil of about 22° Baume. The adopted are as follows: (1) The upper.sail.ds 

lightest oil reported is 26° or 27° Baume, but along the crest of the Thirty-five anticline in 

there appears to ·be very little indeed of oil so the S. ·! sec. ·36 are not produc.tive down -the 

light as this. . The average . for the area is, flanks of -the fold but are there occupied' by 

betw~en 18° and 20° Baume. water. (2) The unconformity which separates 

SUGGESTIONS FOR FUTURE WORK. 

the Etchegoin and the underlying diatomaceous Maricopa shale causes the Etchegoin 

The A zone is produ~tive along the crest of formation to wedge out rather sharply toward 

·the anticl~e in the S. ! sec. 36 and the north the west, and therefore the B zone is much · 

edge of sec. 1, where it has yielded moderate· thinner in the western part of the area than in 

amounts. of. fairly heavy oil. This-part· of the· the eastern part. Wells may safely be drilled 

area has been so· thoroughly <4'illed that the to· depths of several hundred feet below the 

sands in this zone are· probably now pretty top of the B zone in the eastern part and 

well draiil.ed. There is, however,. enough oil. should be drilled th~t deep in order to peneremaining in it to make it worth while· to pro- trate c9mpletely the oil-bearing measures of 

duce from these sands, and in order to protect the Etchegoin, but in the western part of the. 

them great care should be exercised fu. hand-. area drilling more than 100 or 200 feet below. 

ling wells that are drilled along the edge ·of the the top of the B zone is very hazardous, for it 

area in which the top of the A zone is contoured is almost sure to penetrate water sands in,the 

on Plate III, for. it is from such wells- that diatomaceous. shale. (3) The diatomaceous 

trouble is to be expected from edge water in shale contains lenses of oil sands that· have 

the A ~one. Unless these wells protect the A yielded moderate· amounts of ·oil ~long' the 

zone the oil sands in. it will be. ·flooded higher crest of the anticline. The amount of. oil in 

on the anticline. these lenses is, however, not very great, &nd 

.The B zone yields n1ost of the oil in.this area. their deyelopment may well- await the· final 

_In the western part of the fi!ea, . where the draining of the sands of the overlying EtcheEtchegoin forn1ation is thin, the· chief pro- goin formation. 
140 THE SUNSET-MIDWAY OIL' FIELD, CALIF.-PART I. 

MARICOPA FLAT. 

[Southeastern pa~t of sec. 31, sec.· 32, southwest corner·of 

sec. 33, T. 12 N., R. 23 W.; western part of sec. 4, northern 

part of sec. 5, and northeastern part of sec. 6, T. 11 N., 

R. 23 W.] . . 

LOCATION AND OPERATORS. 

The most productive part of Maricopa Flat 

is included in an area whose southwest corner 

lies~on the southwest side of a small hill (elevation, 617 feet) about 2 miles northeast of the 

town of Maricopa and which extends eastward 

from ~hat point for about .1! miles. (See geologic sections, Pis. ~VIII-XXXI, and map, 

Pl. XLIII.) The companies operating here 

in1916 were the·Kern Trading & Oil, Maricopa 

Northern, Midway Northern, National Pacific, 

Maricopa Star, Spreckels, General Petroleum 

(Annex and Essex), Obispo, Pacific Midway, 

Maricopa Consolidated, :Midland Oilfields, Californian Amalgamated, El Dora, Trojan, Miocene, Pacific Petroleum, Midway Fields, Lakeview No. 2, Union (Jergins, International, and 

Midway Fields). 

GEOLOGY. 

pletely masked by the alluvium that fills San 

Joaquin Valley. 

The Thirty-five anticline is slightly asymmetric, the dip on the south flanks being a little 

steeper than that on the north. Also the fold 

is fairly sharp, and the belt near the axis of the 

fold, where the beds have a low dip_:_that is, 

what may be called the crest, of the fold-is 

fairly narrow, being as a rule not more 'than 

1,000 or 1,500 feet across.· 

On, the. south the Thirty-five anticline is 

separated from the Temblor Range by the 

Phoenix syncline, the axis of which .lies' about 

4,000 feet south of the axis of the anticline. 

Practically all of this area is covered with 

alluvium, the only exposures of the older beds 

occurring on the northeast side of the small hill 

(elevation, 617 feet) in sec. 23, and the structure 

must be interpreted entirely from well records. 

OIL SANDS. 

Generalfeatures.-The productive zone in 

this area lies in the lower part of the McKittrick 

group-that is, entirely within the Etchegoin 

formation-the Paso Robles formation here 

The chief structtrral feature is the Thirty- ·containing onlywaterwith traces of tar and gas. 

five anticline, which trends in a general south- . One or two wells have entered the Maricopa 

easterly direction through the south-central shale, but these wells got very little if any oil 

part of the area. This fold is the southern- in that formation. 

most of the larger folds that head in the main The productive zone ranges in thickness· 

Temblor Range and extend southeastward from about 350 feet to more ~han 1,000 feet 

into the valley, where they plunge and cease to and is· thinnest at the southwestern edge of 

affect the surface ro.cks. the area. This variation in thickness is due to 

·Just west· .of the area here described the the uricollfor,mable relation existiifg between 

Thirty-five anticline trends almost due east the McKittrick group and the underlying 

and passes through the center of the S. ! sec. 31. Maricopa shale and to the fact that· the 

In this part of its course it plunges eastward at McKittrick deposits were hiid down in a 

an angle of about 6°. Near the southeast c9r- transgressing sea, so that westward from the 

ner of sec. 32 the axis of the fold swings gradu- valley younger and younger beds rest upon the 

ally to a more southeasterly trend, and in the Maricopa shale. Thus many of the sandy 

NW. fsec. 4

1 its course is aJmost exactly south- beds that underlie the eastern part of the area 

eastward. In this part of its course the fold do not extend under the western part but are 

plunges eastward a little more steeply, the aver- truncated along the plane of unconformity. 

age angle of plunge being about 9°. The anti- Inasmuch as the sandy beds in the basal part 

cline flattens markedly near the center of sec. 4 of the McKittrick are the beds from which the 

and probably does not continue much farther oil ,ls obtained,· the. disappearance of certain 

southeast. It is possible that the fault which of them is of considerable economic importance. 

trends northward down Cienaga Canyon, pass- This condition of affairs is shown ·diagrammating through the ;E. ! sec. 17, T. 11 ·N., R. 23 W., ically in the ·geologic sections (Pls. XXVIIIcontinues as far northward as sec. 4 and actu- XXX), particularly' in Plate XXIX. 

ally·. truncates the east end of the Thirty-five The stratigraphically lowest oil sand in the 

anticline, but this hypothesis is of course not McKittrick group that has been developed in· 

susceptible of proof, for the rocks are com- this area up tq the present time (July, 1916) 

0 
MARICOPA FLAT. 141 

• ·~- is that encountered in the Midland wells Nos. on Plate XLIII. A line drawn from the 

3 and 4, in Midway Northern No. 2, 11nd in vicinity of Kern Trading & Oil Co. well No. 25, 

some of the General Petroleum and Spreckles in sec. 31, to the vicinity of Kern Trading & 

wells. These wells are situated along the Oil Co. well No. 36, in se0. 5, separates approxinortheastern edge of the area now· drilled, and mately the area on the.northeast in which this 

'the lowest oil sand they encountered appears water sand divides the upper zone into two 

to be practically at the base of the McKit- parts and that on the lSOuthwest in which this 

trick group. It is almost certain that farther water sand is absent. 

... 

''•·. 

northeast still older beds underlie this pro- The sands in this .upper part of the productive 

ducing sand and overlie the Maricopa shale, zone becm~e rather lean or lack oil entirely 

and these older beds probably contain some along the edg(_:) of the area contoured on Plates 

oil sands. It is not very probable, however, III and XLiii and many of the sands that 

that the zone in which productive ·oil sands contain oil closer to the crest of the fold are 

occur increases in thickness eastward from the· here filled with water. 

area in which the wells just mentioned are The oil yielded by the sands in this upper 

situated,. for in that area the uppermost sand part of the productive zone ranges in gravity 

that has yielded so much oil in the western part , from 17° to 24 ° Baume. The sands in the 

of sec. 32 is lean, and to judge from conditions lower· part ·of this division contain .oil of somealong the foothills west of Taft, farther. east, what lighter gravity than those in the upper 

this upper sand probably contains water. In part, and in the eastern part of this area, where 

the area northeast of that which has been many of the wells produce only from the lower 

developed the productive zone is thickened ·by sands, the oil obtained is of about 26° Bam.ile. 

the addition of beds at the base and thinned In this same part of the area the sands in the 

by the subtraction of beds at the top that are upper part of this division-those lying above 

occupied by edge water. ~he net result is the prominent edge-water sand whose position 

that the thickness of the productive zone is is show;n on .Plate XLIII-yield oil of about 

maintained fairly constant. · · 19° Baume. · .. 

In sec. 32 the productive zone may be con- · },fiddle division.-The middle division of the 

sidered ~ composed of three main par,ts:.._an productive zone extends from the bottom of· 

upper oil sand, a :middle division occupied by the upper division just described to the bottom 

water sands With lenticular oil sands, and a of the big water sand that lies a short distance 

lower division containing nu:merous oil sands, above the so-called· Wilh~lm sand. This clivithe chief producing sands of the area. sion varies somewhat in thickness. It is about 

· U1Jper sand.-The uppermost of the divisions 100 feet thick near the southwest corner of 

just n1entioned varies slightly in thickness and sec.' 32 and is probably between 250 and 300 

has a maximum of about 150 feet. It is not a feet thick near the northeastern edge of the 

single sand but is composed of' a number of part of sec. 32 contoured on Plate XLIII. The 

more or less lenslike sands whose thicknesses variation in thickness is shown in the geologic 

vary considerably, though few of them are over sections (Pis .. XXVIII-XXXI). · 

25 feet thick. More of these individual oil Most of the sands in this zone are occupied 

sands are· recorded in the· wells drilled near by water arid not by oil, but some oil sands 

the axial part of the ~nticli.ne than in those ·occur both near the top and immediately above 

down the flank of the fold or eve'n down the · the big water sand 'that marks the bottom of 

plunge to the east', but the total thickness of ~his zone: The chief water sand here is the 

the zone is abnost the same in both· places. mie that yields a large flow of water and occurs 

The top of this zone is shown by the contours a short distance above the so-called Wilhelm 

on Plates III and XLIII. sand. This sand varies in thickness but is 

This upper part of the productive zone does usually reported ·as being from 20 to 25 feet 

not, however, contain water near the crest of thick. Near the southwest corner of se.c. 32 

the anticline, whereas down the east flank .a this water sand has not been recognized in sevpersisten.t water sand is recorded in the very eral of the deeper wells, whose logs have renlidclle of it. This· water sand is shown in corded a gas sand at the horizon at which this 

.Plates L"\:VIII-XXX, and its top is contoured. water sand should occur. Almost all these 
142 THE SUNSET-MIDWAY .OIL. FIELD; CALIF.-PART I •. 

wells. which have not cased off this gas sand ·Th,is divisiqn has a maximum thickness of at 

have later had wa~er trouble, and it is prac- ~e~~~ 40.0 fe~~;· f~r wells near the c.enter of sec. 

tically certain that this sand contains water 3p ·ha;y.e pe~etrated it to that depth without· 

only a short distance- down the dip from the h~vil!g :ente~~~d the underlying. diatomaceous 

pl~ce. where the wells penetrated it, and that sh~e .. _;Like .t}le uppermost division, it is made 

water. moves up the dip. when the gas is up of .a nu:mber of oil sand's or lenses separated 

exha~sted. · · . by barr~n strata. The individual oil sands 

The top of this big water sand is contoured ,vary._in th~c~ness, but the average is probably 

on Plate XLIII, but in usip.g this. map it should less than ~-_o. feet. To these oil sands a great 

be ;remembered that water s.ands occur locally nu~ber .~f,. names have been applied-for iri-

~;Lbove this sand up to the base of the· upper oil st~nce, .W.ilhelm, Obispo, Spreckles, American, 

sand which has just been described, and also Kinsey,. Miocene, and Lakeview No. 2. In . 

'that in the northeastern part of the area .con- ge~eral, particularly in sec. 32, the first oil 

toured on the map other water sands occur sand below the big water s·and is called the 

below this big water sand and above the first Wilhe1In,.sand. . · 

underlying oil sand-that is, the sand usually Near the s()uthwest corner of sec. 32-..,--that is, 

called the Wilhelm sand. near the 'crest of the anticline-the uppermost 

. The big water sand appears to be widespread productive oil sand in this lower division lies a 

and to extend to the southeast at least q,s .far very short. distance bel~w the base of t4e big 

as the center of sec. 4. The water sands that water sand that occurs in the lower part of the 

occur a short distance above the pig water ·middle· . 9.ivision of ·the productive · zone, in. 

sand are lenticular and probably not ver.y. ex- places ~ot more than 25 feet of clay separating 

tensive, although some· of them yield flqwing the. two:·.·' 'l'he distance between the big water 

water.· The water that occurs below. the. pig ·sand anq the underlying oil sand, however, inwater sand is probably edge water in the. sands creas~s. down the flank of the fold. The reason 

that, close ·to 'the crest of the anticline, yield for . tl;lis. apparent separation of. ·the sands is 

oil-that is, the sands milled the Wilhelm sand probably to be explained by the fact that the 

in the southeastern part of_sec. 32.. . . .. . sands., t~at .are filled with oil near the axis of 

A few of the wells near the southwest corner the a,n.-t~~~iJ;le become barren down the dip and 

~f sec. 32 record a heavy .oil (about 14 ° Baume} are _in. pla~es occupied by water. Thus near 

immediately above the big water sand or, more ~h~· .. c.ent~r of sec. 32 the uppermost oil sand 

precisely, above the sand recorded as contain- ~- .t~s l~w~r division of the productive zone. is 

ing .gas, .which is really the equiv.al(mt of the· the equiv~lent of the oil sands that occur a 

water sand. Heavy oil is reported· also in !1 · CQJ1st~er.able distance below the uppermost prosimilar position just above_ the big,_water sal).d: _d~~~~~~.~il sands in this division near ~he crest 

near the center of sec. 4. Such a sand con- of .the anticline. On acc.ount of this conditi'on, 

tainingheavy oil probably occurs in other. parts .~lt4?~g~ the name Wil~elm sa~d is .applied by 

of~~e ~re~, bu~ it has not bee~ reported in t~e. tJ;le. ~.rillers to the :first productive oil sand en~ 

logs of the de~p wells. This_ sand would prob- C?:tfP.~re,d below. the big flowing-water· sand, 

ably yield a fair production, bu~ the und~rlying this ~aiJJ.e· i~ not always applie.d to the sam~ 

sands are so much richer that it has be~n dis- sand .. This condition is shown in the geologic 

regarded. Th~ heavy gravity of the oil, it ~e~~ions (Pls. XXVIII-~!) .. 

yields also ~akes it unattra:ctive at present.. :' . ,As yet water has not been reported in this 

This middle division is really characteriz~d. i<;>w~r . division of the productive zone~ The 

by water, not. by oil, and should. be cased off only wat~r.that has so far been reported below 

in order ~o protect both the upper oil sands,· tp.e big flowing-water sand that :r;n.arks the base 

already descriped, and the lower oil sand, de- of the middle division almost certainly occurs 

scribed below.,. below the base of the productive zone. This· 

Lower divi$ion.-The lower division embraces water was reported_ in the w~stern part of the 

all of the productive zone lying below the base area, and there, on account of the unconformity 

of the middle division-:-that is, below the big at the base of the. productive zone, the sands 

water sand and above the top of the Maricopa -~hich. form the lower part of . the productive 

shale, both of which are contoured on Plate zone in the center of sec"' 32 are absent. 

XLIII. . . · This lower water sand is shown in Plate XXX. 

• 
M;ARICOPA FLAT • 143 

. WATER SANDS. her of. water sands that. yield flowing salt water.2 

The l~rgest yield comes .from the sand which· ·Top water.-The records of the upper parts of the wells drilled in this area are not very occurs in th~ lower part of the division. The 

t_op <;>f this big water sQ.nd is ~ontoured on 

good, for most of the wells were ·drilled with flate XLIII. This water sand is very perrotary tools, and many of the drillers made no sistent and occurs beneath most if not all of 

special attempt to keep a careful record of anythin . t d b th . . . t il the area here described~ Along the crest of the . dg eHncoun ere t a ovet e ':1-ppermotst 0 d anticline near the southwest· corner of sec. 32 

san . owever, op ·wa er occurs sea ere hi d · · 1l d d 

thr h th d d t 1 . 1 ·thin 50 f t t s san was ongina y reporte as a gas san 

oug e san s 0W:O 0 a eve. WI e~ o and in some of the wells was not cased off. 

or so of the top·of this upper ml sand,· and m W'th th · _.::t.. t' · f th t h · · · . d . . · I e e.<'~o.llaus .Ion o e gas wa er as eVI- order to protect the ml san sIt IS necessary to d tl ·k d th d' d h · d · . . f . . en y wor e up e Ip an as appeare In 

carry the water strmg down mrly olose to this th ll Th t d 't lf 1 .

1 d . ese we s. e wa er san I se , as near y as 

01 Tshan · d. · · th t . th II! • can be judged froin the logs, is not thick, P,robe upper water san s- a Is, ose 1ur- bl . · · h f b d' · h' t · f th h ll t . a y averaging not more t an 25 · eet, ut own IllS mg wa er In some o e s a ow wa er th fl ks d 1 d. th 1 1 th 

ll 1 1 · urf 1 b h e an an a so own e p unge a ong e 

we s-o ear y contain s ace water, ut t e t f th f ld t d b bl 1 

lowest of these w:ater sands-that is, · those c~esl 0 e ~ hwa er san s, pro ~ Y. en- . h' 100 f f h t f th . · il ticu ar, appear In t e upper part of this middle 

Wit m eet or s.o 0 t .e 0P. 0 . e upper 0 division-that is, above the big water sand and 

sand-are the· stratigraphic equivalents of those b low th 1 t ·1 d f +.h d' · · . . e e owes oi san o v e upper IVlSion 

that Qontam oil farther to ,the west, namely, the f ·th p d t' (S PI XXIX ) 

d Pl III f h . o e ro uc Ive zone. ee . . A zone ·oontoure on ate or t e regwn Ed t · p : th d' · · f . . ge wa er a pears In e upper IVIS10n o 

about Mar1~opa. Thus ~he water of thes~ the productive zone in much of sec. 32 'on the 

lower sands IS edge water 10 the -:t zone. . north flank of the anticline and along the crest 

Bottom water.-8o far only a Singl~ well has of the fold east of the center of the north line 

encountered ~hat may truly .be termed bottom of sec. 5. This water is very troublesome, for 

wate~-that IS, water that hes b.elow ~he_ pro- in· much of the area it is separated from the 

. d~ctiv~ zone. ~he water sand ~s almost cer- productive oil sand by only a very thin stratum 

. taull~ In the ~ar10opa sh~le, ?u t h ttle II_1°r~ can of. clay, which in places is recorded as only 

be smd ~efinitely re.garding I~ ~ro~ this Sing!e 10 feet or so thick. This edge water separates 

record. It~ appro~Imate po.sitwn Is shown Ill' tbe ~pper division. into two parts, the upper of. 

tho geolo~I~ se?twn formmg Plate ~~· which yields oil of about 19° Bau~e and the 

From conditw~s ·In other parts of ~he :H~ld It IS lower oil of 25 o to 27o Bau!I\e. Its .position is 

probable· that m the area. under discusswn·~he shown.by the contours on Plate XLIII. · upper part of the Mancopa shale contams · · · · · · 

numerous water sands which will yield flowing CHARACTER OF THE OIL. 

salt water, for the presence of su~h water sands The oil sands that make up the 'productive 

has been shown by deep Wells drilled in the zone contam oil of different quality;· In genvicinity of Maricopa. . eral the heavier oil is found in tl;le upper part 

Edge water and water in the oil zone.-rhe · of the zone, iii those' sands that lie close to 

most troublesome water in this area is that water sands. In the ·western part of the area 

encountered in what has been ·described above the sands that constitute what has been deas the middle division of the productive zone. scribed as the upper division of the productive · 

This division ranges in thickness f:r:om about zone yield oil of 17° to about.24° Baume, the 

100 feet to about 200 or 300 feet. Its thick- average being about 21° Baume. However, in 

ness varies with its position in the area, being the eastern part ·of sec. 32, where this upper 

least along the crest of the anticline near the division is separated into two portions by the 

southwest corner of sec. ·32 and gr~dually in- water sand whose position is shown on Plate 

creasing from that locality both northeastward XLIII, the portion lying below the water sand 

down the flank and eastward along_ the crest yields oil of 25° to 27° Baume that is of pracand down the plunge of the fold. This middle tically the same quality as that obtained from 

division of the productive .zone contains a num- the lowest division . of the productive zone. 

1 See nnalysis 8, Table 15, Part II (Prof. Paper 117). 2 See analysis 9, Table 15, Part II (Prof. Paper 117). 
144 THE SUNSET-M~DWAY OIL FIELD, CALIF.-PART I. 

The sands of the lowest division of the productive zone yield oil of 24 ° to about 27° 

Baume. A sand lying a short distance above 

the top of the big water sand that occurs. in· the 

lower part of the middle division of the productive zone yields oil_of 14° Baume. 

PRODUCTION. 

the production must be expected from the 

sands that lie in what has been described as the 

lowest division of the productive zone, along 

the axial part of the fold in sec. 32, or from still 

lower sands which are not present in sec. 32, 

but which wedge in below the beds that form the 

lowest division of the present productive zone . 

there and the underlying diatomaceous shale. 

·The initial production of wells in this areac Thes_e sands of the lowest division ?f the pr?-

has varied .greatly, ranging from less than 100 duc~Ive zone _are the ones from w~ICh t~e b~g 

barrels to many thousand barrels daily. The floWing wells I~ sees. 32 and_4 d~rive their oil. 

productivity of each well depends both upon ~hey unq~estwnably contain oil for a conits position in the area and upon the sand from siderable distance both to the east and to the 

which it obtains the oil, the wells .along the' north of the area wh~re they hav~ been ta~p~d 

crest of t4~ fold and penetrating the sands of by wells. However, the quantity o~ oil In 

the lowest divisi<?n of the productive zone these lowe: ~ands · away fro~ the aXIal part 

yielding the most oil. The largest well in the of the an~IChne can no~ be-In any w~y comarea was well No. ·1 of the Lakeview No. 2 Oil parable w1tl} the. quantity they contain along 

Co., whlch is said to hav~ flowed for a time ~t the crest of that fold, for in this area the beds 

the rate of 50 000 .barr~ls· daily. A summary dip regularly to the northeast betwe.en the 

of the history' of.this -~eil is given in another. axis of t~e Thirty-five anti~line and, the axis 

part of this report (p. 66): 9~ the ow hole this of the Midway Valley synchne. The amount 

·area has proved one of the richest in the whole of dip of C<?urse decreases toward the syncline, 

field. · · · · but so far as is known there is here no area of 

SUGGEST~ONS FOR FUTURE WORK. 

The wells so far completed have pretty thoroughly outlined the general position of the 

se~eral oil and water sands, and· in drilling 

new wells in this part of ·the area attention· 

should be paid to three chief points-protecting the upper oil sand from top water; protecting the upper oil sand from water that 

occurs beneath it, in what has been described 

as the middle division of the productive zone; 

and proteGting the oil sands that form th~ lowest division of the productive zone from water 

in the overlying sand~. 

The sand that forms the upper part of the 

productive zone appears to contain oil in commercial amounts in almost all the are~ along 

the crest of the anticline and down the north 

flank approximately to a depth of 2,100 .feet 

below sea level. The area on the south flank 

of the anticline in which this uppe,r sand will 

prove productive has nQt yet been outlined by 

drilling, but on account of the. fact that the dip 

is somewhat ,steeper on this side of the fold it is 

probable that this sand will not prove productive to quite so great a depth as on the north 

flank. · · 

Farther down both the northeast flank and 

the crest of the fold than where the upper sand 

lies approximately 2,100 feet below sea level 

reverse structure along which oil would tend 

to collect. The conditions are therefore conlparable to those in the west side of Midway 

Valley northwest of Taft, in the northeastern 

part of sees. 10 and 14 and the southeastern 

part of sec. 11, T. 32 S., R~ 23 E. 

On the south flank of the Thirty-five anticline the sands that form th.e lowest division 

of the productive zone in sec. 32 become thin 

and gradually we~ge out. Therefore in the 

western part of the area here de~cribed production must be expected chiefly from the 

upper division of the productive zone. In the 

eastern part of the area, however-that is, in 

sec. 4 and the eastern part of the N. ! ~ec. 5-

the sand forming the .lowest division of the . 

productive zone in sec. 32 occurs, and in the 

part of the area away from the crest of the 

Thirty-:fiv:e anticline the production must be 

e~pected from this sand. · · 

'fo the southeast, down the plunge of the 

Thirty-five anticline, the field has p.ot yet been 

delimited by drilling. The wells in.sec. 4 have 

shown, however, that th~ sands in the lower 

part of the upper division. of the productive 

zone in sec. 32 contain oil in commercial 

amounts at least as far southeast as the point 

where the sand lies 2,200 feet below sea levelthat is, somewhat lower than along the north 

flank. 
MARICOPA-PIONEER AREA. 145 

It is possible that the fault which trends 

northeastward down Cienaga C~nyon may 

continue out into the flat to the vicinity of 

sees. 10 and 4 and that it cuts off the Thirtyfive anticline in this area, but definite evidence on this point is not available. 

MARICOPA-PIONEER AREA. 

[Southeast corner of sec. 34; southwest corner of sec. 35, 

T. 12 N., R. 24 W.; all but north edge of sec."1, all but 

southwest corner of sec. 2, northeast corner of sec. 3, 

eastern part of sec. 12, northeastern part of sec. 13, 

'1'. ll'N., R. 24 W.; southwest corner of sec. 6, western 

part of sec. 7, sec. 18, southwestern part of sec. 17, T .. 11 

N., R. 23 W.] . 

LOCATION AND OPERATORS. 

The Maricopa-Pioneer area embraces the 

foothills west and south of the town ,of Maricopa, extending from a point about a mile west 

of Monarch southward to a point about ·a mile 

east of the old refinery at Pioneer. The companies operating here in 1916 or claiming land 

upon which wells had been drilled previous to 

that date were the Midway Oil Co., Sunset 

Monarch, Ruby, Petroleum Center, McCutcheon, United Crude, Case, Midway ·view, Ida 

May, Adeline Co:qsolidated, I-Ianford Sanger,· 

Standard, Kern Trading & Oil, Lowell, ~1elita, 

Muscatine, Vancouver Midway, Sunset ~1ohawk, La Blanc, General Petroleum, New 

Center, Snook, Petrolia, Northern, Good Roads, 

Golden West, Consolidated Midway Chief, 

Topaz, Union, Yellows~one, Munzer, Johnson, 

and I-Iazelton Crude. 

GEOLOGY. 

This area lies on the south flank of the 

Phoenix syncline, extending from the axis of 

that fold southward to the fault that trends 

northeastward down Cienaga Canyon. On 

the west it extends almost to the ·outcrop of 

the oil sands of the McKittrick group. The 

structure of the beds is somewhat irregular, as 

is to be expected, for the are~ lies at the very 

southwest corner of San Joaquin Valley, where 

the San Emigdio and Te:r;nblor ranges join. 

As is explained on pages 57-62, the structure 

of the San Emigdio Mountains is very different 

from that of the Temblor Range, and this 

area in which the two ranges meet exhibits in 

part the features of one range and in part those 

of the other. Near the · fault at Cienaga 

Canyon the ·beds are steeply tilted and probably fractured. At the northwest end of _the 

. 109288°-19-10 . 

area there are numerous small folds, of which 

the larger are· the California Fortune and the 

Sunset' Monarch anticlines. It, is probable · 

that in this part of the area there are several 

other small folds similar in character to these 

·two, which are mapped. 

OIL SANDS. 

Divisions.-The producing sands lie in two 

chief divisions, one comprising sands that correspond to the prodqctive sands in the rest of 

the district and lie in the basal part of the 

McKittrick group, and the other occurring in 

the upper part of the Maricopa shale.. The 

upper of these two division.s comprises the 

A and B zones, whose tops are contoured on 

Plate III. The A zone may include near its 

top some beds of the Paso Robles formation. 

The B zone is entirely in the Etchegoin forma- ~a . . 

A zone.· -The A zone, which is productive in· 

the western part of the area, lies stratigraphically between 200 and 300 feet above the top 

of the B zone. Its thickness varies on account 

of the unconformity at the base of the McKittrick group, and in the northwestern part of the 

area it is less than 100 feet thick. Within the 

area where the A zone is con toured on the 

map (Pl. III) most of the zone is reported as 

oil sands, the amount of intercalated clay being 

notably small. 

The A zone embraces the upper part of the 

productive sands in the· vicinity of Pioneer, 

but on account of insufficient data the' whole 

productive zone there is mapped with the B 

zone. The A zone is not productive in the 

axial part of the syncline east of the area where 

it is contoured on the map (Pl. III).· 

B zone.-In the northwestern part of the 

area the B zone is wedged out,· by the unconformity at the base of the Etchegoin formation, a short distance west of the area where 

it is contoured on Plate III. The thickness of 

the B zone increases to'Yard the east, and in 

the trough of the Phoenix syncline near the 

center of the east line of sec. 6 the top of the 

zone is probably 400 or 500 feet above the 

top of the Maricopa shale. This zone, like the 

overlying A zone, is, where productive, reported 

chiefly as oil sand with relatively little interstratified barren shale. . · 

Oil in the Maricopa shale.-Many of the 

wells drilled in 1916 and even a few of the 
146 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

wells drilled earlier have derived considerable of oil have been reported deep in the shale, 

oil from the sandy lenses in the diatomaceous but no oil was found ill commercial amounts. 

shale, and late in 1916 and early in 1917 sev- CHARACTER. OF THE OIL. eral of the compatiies .he.r:e ,were drilling for the 

<;I~eper· :sands.·; 'rl;l~s~. ·o~-be;~ring lenses are, The oil r~nges in gravity froni 11° to 18° 

·however,· so .irr~g:ularly .distributed and lenses · Baume ·and. averages about 14° Baume. The 

that contain water are so abundant that it is heaviest oil eomes from the upper part of the 

difficult to. produoe o.~ f~om th~se sands. A zone in the western part of the area. Some 

WATER SANDS. 

Top water.-The logs of most of the old 

wells in the northwestern_, part of the area, 

where the p:r;oductive sand~ lie in the A _zone, 

report water 1 in sands .. that ·lie ~bout 100 feet 

above''the top o; that zone,,but none of .them 

reports water below the top of it.· Top water 

has been successfully . handled . in this part of 

the area by setting the ·water string a relatively. short· ~istance above the top of the A 

zone.· 

F;dge water.-The A zone is oc·cupied. by 

Qf the wells have' obtained oil of 17° or 18° 

Baume in the fine-grained beds in the Maricop~ shale. 

PRODUCTION. 

· . The production· of the wells in this area is 

small compared· to that of the rest of the field. 

Some of the wells have produced 500 barrels 

or so when first brought in ·but have maintained l3<? great. a yield for only a d.ay or so. 

Most of the wells are now reduced to a daily 

productiolf of much less than 100 barrels, an¢! 

many of theJ? pump less than 20 barrels. 

water east of Maricopa, at the south end of PIONEER ANTICLINE AREA. 

the area where the top of that zone is con- [Southwest corner of sec. 15, southern part of sec. 16, 

toured ·on Plate III. Also east of the area southeast corner of sec. 17, eastern part of sec. 20, sees. 

where this sand is contoured practically all 21 to 28 inclusive, all but northwest corner of sec. 29, 

the A zone coiltains water. In this- part of sees. 33 to 36 inclusive,· T. 11 N., R. 23 W.] 

the ar~a the water is considered top water and LOOATION AND OPERATORS. 

is· shut off a short distance above the top of The Pioneer anticline area lies ·in the footthe B zone. hills southeast of. Sunset, embracing the ridge 

Bottom water.-A ·great many of the wells that lies east of Cienaga·Canyon and a belt of 

have been drilled several hundred feet, below San Joaquin Valley about 2 miles wide borthe top of the B zone, and many of them have dering this ridge. (See Pl. .XLIV.) The 

entered the underlying Maricopa shale. Most northwest oorner of the area lies about 4 miles 

of these wells report water 2 at a variable southeast of Maricopa; the east end of the 

distance below the top of the B zone. It is. area lies about 1 mile east of Santiago Creek. 

difficult to make ·out the exact position of The Western Minerals Co. is the chief. operathese water s~nds, but it seems probable that tor in this area and has drilled seven wells, 

here, as in the area north of the. town of all of which were idle in -1914. Other wells~ 

Maric.opa, water occurs chiefly in the diato- all of them dry, have been drilled by the Van-

~aceous .shale. ·:rhe distance that it is safe couver Paraffine Oil Syndicate in sec.· 23, the 

to drill belo~ the top of the B zone is there- Nevada Pacific Oil Co. in sec. 24, the Test 

fore dependent upon the thickness of the Oil Co. and Thirty-four Hill Oil ·co. one each 

Etcliegoin formation, and this distance in- in sec. 34, and the .El Cerrito· Oil. Co. in sec. 

creases toward the east. It.may be that some 35. Besides these wells three holes were drilled 

of 'these .water sands occur in tP,e Etchegoin, by Jewett & Blodgett in the NE. i sec. 28 in 

but certainly most of ·them lie below it. the early nineties-for thi~ area was one of 

. Many ·of the sandy lenses in the Maricopa the first parts of the Sunset field to be prosshale ha-ye yielded several thousand barrels of pected, the seeps near the north line of sec. 

water daily.2 ·One well has been drilled 2,800 20 having· early attracted attention. These 

feet below the top of the B zone, the lower old Jewett & Blodgett wells obtained small 

~,300 feet of this ·in the Ma:r~copa shale. Traces quantities of light 811 (about 30° Baum.e). 

They .are describ'ed more fully in the section 

on the eariy ~istory _of. ~he :fi,eld (pp. 63-66). t See analysis 3G, Table 20, Part II (Prof. Paper 117). 

'For analyses see Table 27, Part II (Prot Paper 117). 
35° 

U. S. GEOLOGICAL SURVEY 

SUNSET 

SECURITY 

19 

BUICK 

30 

Structure contours 

showing top of oil sands in basal , bed of McKittrick group 

Structure contours 

showing approximate rosition of productive sands in upper part o Vaqueros formation 

Structure contour interval 100 feet 

Datum is mean sea level 

X 

Oil seep or tar sand 

The wells are those shown on Plate III 

PROFESSIONAL PAPER 116 PLATE XLIV 

W. A . BOYNGE 

16 - --- 1--+---------.:.1 5 14 13 

2~ 24 

33 36 

-soo 

CIENAGA .J, SYNCLINE; .o. 

1' 

119° 181 

MAP SHOWING POSITION AND STRUCTURE OF OIL SANDS IN OLD SUNSET OIL FIELD, T. l1 N., R. 23 W., CALIFORNIA 

Scale :i4i5,oo 

o ~ 1 2 Miles 

C====c==~¢===~===3==================~ 
PIONEER ANTICLINE AREA. 147 

GEOLOGY. In the wes-t-central part· of the area the 

upper part of the Vaqueros formation crops 

out in ·the axial part of the Pioneer anticline. . \ 

The formation here is ·composed chiefly of 

dark. chocolate-colored sandy shale which· is 

probably in part diaton1aceous and in plQ.ces 

contains a considerable amount· of carbonaceous .matter as minute flakes. On the south 

limb of the anticline and in the axial part of 

the Cienaga syncline· the Vaqueros formation 

is overlain by the Maricopa .shale, but on the 

north limb ofo the anticline it is overlain directly by. the· coarse gravels and clay- of. the 

McKittrick group, the siliceous Maricopa shale 

having been overlapped .some distance north 

of the axis of the .anticline. 

POSITION OF THE OIL SANDS. 

Tbjs area is separated from the south end of 

the 'Sunset field by the belt of irregular structure that trends northeastward through sees. 

17, 20, and ~9, T. 11 N.·, R. 23 W., and probably_ by another similar belt tl,lat' passes 

through sees. 15, 21, ~nd 28 .. In these belts 

the beds haYe broken along one or n1ore faults. 

The exact nattue of the faulting ca,n not be 

described, for the rocks affected are largely 

coYered 'by alluvium. The interpretation that 

best fits the ~:nrailable evidence is that the chief 

break has been along a line extending down 

Cienaga Canyon and thence trending about 

N. 20° E. tlu-ough sees. 20 and. 17 across the 

flat. The rocks east of the fracture have 

mo-ved upward 1:elative to those on the west. 

The probable position of the fault is shown on 

Plates II ·and XLIV. It is also probable 'that · The oil-bearing sands in this area lie in two 

a second but stnaller parallel fault extends chief zones. The upper zone includes the 

through the central parts of sees. 21 and 16, sandy beds in the basal part of the McKittrick 

but here the relatiYe n1ovement is apparently group and in places some of tho~e in the upperopposite to that along the major fault to the most part of the formation upon which the 

west, and the rocks lying to the west of the McKittrick rests, whether that formation is 

fracture have been raised relative to those on the Maricopa shale or the Vaqueros formation, 

the east. The evidence of the existence and for in this area the McKittrick overlaps' each 

position of this fault is, however, so meager of these formations. This zone corresponds 

that it has not been shown on the map (Pl. to the chief zone that yields the oil in the main 

XLIV). part of the Sunset and Midway fields to the 

Besides these faults the chief structural fea- north. The lower zone includes sandy beds in 

tures in this area are the Pioneer anticline a~d the Vaqueros formation and is the zo:p.e of 

the Cienaga syncline. The anticline trends chief importance in this area. The two zones 

almost clue east through the central parts of yield oil of distinotly different character.· 

sees. 28 and 27 and may be traced in the out- That in the upper zone is a heavy, darkcropping beds as far eastward as the we'st line colored or practically black tarry oil of approx~ 

of sec. 26, where the rocks affected by it are imately 14° or 15° Baume. The oil in the 

C0\7 ered with alluvium. The fold, however, lower _zone .is greenish and muoh lighter, usncontinues s01ne dista~ce eastward, probably ally of 25° to 28° Batime. A few samples· 

at least as far as the east line of the township. of oil from the lower sands are recorded 

In theW. ! sec. 28 the anticline abuts against as of only 19° Baume, but the relatively 

the eastern one of the two fault zones just heavy gravity of these samples may· be the 

described, and, although the Pioneer anticline res·p.lt of a mixing of oil from the· sands in the 

is evidently part of the anticline that may be Vaqueros formation with the heavier oils of 

traced from Cienaga Canyon westward to Bit- the upper zone, of a loss of the light oonstitterwa'ter Creek, the two can not be traced across uents in the oil through evaporation, or of 

the fault zone into actual connection. (See contaot with alkaline water. ·The normal oil 

geologic m.ap, Pl. II.) . in the sandy beds of the Vaquer9s formation 

Near the east line ofT. 11 N., R. 23 W., the is evidently lig~ter than 25° Baume. 

Pioneer anticline and the Cienaga ~syncline 

plunge eastward. The degree of plunge can: O~L I~ THE VAQUEROS FORMATION. 

not be estimated accurately, for this part of OIL sANDs. 

each fold is cov~red by alluvium, but it is prob- .The oil in the Vaqueros formation occurs in 

ably less than 10°. . various lenticular sands interstratified with 
,.;J·· ....... 

........ 

148 THE SUNSET-MIDWAY OIL J<'IELD; CALIF.-PART I. 

the sandy clay and chocolate-colored shale 

(probably in part diatomaceous) that compose 

the upper part of the formation here. Oilbearing beds are appar~ntly scattered· through 

the upper shale JI.lember of ·the formation, but 

only a few of the lenses contain commercial· 

amounts of oil, for many of them are noted 

only as "showing" oil when·penetrated by the 

drill. Most of the oil has come _fro:r;n .thin sands 

that lie in the lower part of the upper shale 

member of the formation. · The wells here that 

have yielded oil are so few and the oil sands 

are clearly so lenticular. that it is impossible to 

contour the pr<?ductiye zone other than in a 

very general manner. 

· On Plate XLIV an attempt has been made 

to show the approximate position of the horizon at which the lenses that. have yielded the 

most oil occur. Anyone using this map should 

·understand that this is only a first approximation of the location of the oil-bearing sands arid 

that these contours do not have by any means 

the: same degree of aocuraoy· possessed by 

those shown on the map of the .productive 

parts of the main fields to the north (Pl. Iii). 

In Inost of the. wells that 'have· obtained oil 

from the Vaqueros sands in this area various 

quantities of oil have been reported in sandy 

beds that lie ma~y hundred feet above the sand 

that has yielded the chief production, and in 

one welllO barrels of oil a day is said to have 

been obtained from a sandy bed that lies almost 

at the top of the Vaqueros-that is, stratigraphically above the lerises that have been tapped 

by the larger wells and above the horizon marked 

by the purple contours shown on Plate XLIV. 

WATE!t SANDS. 

·The records of water· sands encountered in 

the wells so far dril~ed along the Pioneer _anticline are much too discordant to permit any 

very definite statement as to the location of 

these sands. 

The logs of two of the old wells drilled by 

Jewett & Blodgett in ·the nineties reported 

water in practically every sandy bed penetrated> but as water was never shut off properly 

in these wells it is probable that much of the 

\water came from some one or two sands pretty 

high up and that as drilling progressed this 

water leaked down into the hole. The logs of 

most of the wells drilled more recently report 

water in the upper part of the section penetrated, some of them down to levels witpin 

300 feet or so of the productive oil sand. 

Much of this is clearly surface water, but in a 

few logs the deeper top waters are reported as 

sulphurous and are probably comparable with. 

the top waters that lie close to the top of the 

chief oil sands in the main field. 

In two, possibly in three, wells saline water 

is reported below the deeper oil-bearing sandsthat is, those sands which lie in the lower part 

of the upper shale mem her of the Vaqueros 

formation. In on~ well this water is said to 

have flowed, and in another to have risen 

about 800 feet in the hole. 

SUGGESTION'S FOR FUTURE WORK. 

The 'drilling that has been done along the 

eastern half of the Pioneer anticline has shown 

that the shale which forms the upper division 

of the Vaqueros formation contains n1any 

sandy lenses saturated with oil. These lenses 

9ccur at various horizons 'practically from the 

top to the bottom of this shaJe, but the largest 

produ,ction has come from the lenses in the 

lower part of .it. No well can therefore be 

considered as testing the area unless it conlpletely penetrates this shale. 

So far the successful wells here are all fairly 

close together along the axis of the ·Pioneer 

anticline. Most of the wells more than half a 

mile from the axis of the Pioneer anticline 

have, it is true, not been drilled deep enough 

to encounter the basal part of the ,upper shale 

of the Vaqueros formation, but those that have 

been drilled deep enough have not found oil. 

It is probable that the area in 'which the 

Vaqueros .formation contains commercial 

amounts of oil is restricted rather closely to 

the crest of the Pioneer anticline. On the. 

north flank of the fold ·wells half a mile from 

the axis have obtained oil, and it may be that 

the productive belt extends for half a mile still 

farther _north. On the south flank of the anticline the productive belt certainly does not 

extend south of the axis of the Cienaga syncline, for the beds forming the south flank of 

the syncline are practically on end . 

The oil in the Vaqueros formation is light 

and very fluid and apparently does not form 

tarry products 'so readily as the heavier oil 

characteristic of the upper zone. Oil such as 

this would tend to migrate readily and would· 

halt and concentrate only in those areas where 

the structure formed a fairly perfect trap- " 

that is, such a trap as is formed. by the Pioneer 
PIONEE~ ANTICLINE AREA. 149 

anticline. Oil would evidently tend tq collect 5. That the high grade of the oil and the 

in the uppermost part of the fold and would ·regular nature of the folding make t}:lis area 

not accumulate lower on the flanks, unless the a·very promising one for future prospecting. 

porous beds near the ·crest of the fold were In the area lying east of .the fault that passes 

fully saturated (with oil or gas), or unless the ·down Cienaga Canyon and west of a line 

oil in moving up the dip became trapped in a through sees. 28 and 21 parallel to that fault 

r>orous lens that had no outlet up· the dip. and passing close to the westernmost point at 

Further prospecting for' oil in the beds of which the axis of the Pioneer anticli~e is 

the Vaqueros formation should therefore be shown on the map (Pl. XLIV) the strata are 

conducted firs.t along the cr~st of the Pioneer considerably fractured and are not folded in 

n.nticline, and drillers of wells here should be such a way as to form a trap in which petroleum 

prepared to drill completely through the upper would tend to collect. This area therefore 

shale member of the formation. Much of the appears unpromising. 

Vaqueros formation has been removed by A narrow belt along the _west half ·Of the 

erosion along the crest of the anticline in Pioneer anticline, between Cienaga Canyon 

sees. 27 and 28, but the diatomaceous Mari- and the east branqh of Sunset Valley, offers 

copa shale evidently swings about the nose of some promise of yielding petroleum, but the 

the fold beneath the alluvium in the vicinity prospect is not so good in the east end of the 

of sec. 25, and there the full thickness of anticline. The beds are more steeply tilted, 

the upper shale member of the Vaqueros and the crest of the anticline, which is the 

would have to be penetrated to test the area area in which productive sands are to be 

adequately. Sandy beds containing oil might expected, is narrower; the Vaqueros formation 

and probably would be encountered above the .is less eroded, and in consequence the sands 

base of this shale along the crest of the anti- that ·have proved the most productive in the 

cline in sec. 25, but ·no well that· did not en- eastern half of the anticline are more deeply 

counter oil can be said to have proved the hwried; and finally the Vaqueros formation 

area to be barren of oil unless it has been ·here shows no surface indications of petroleum. 

drilled through the shale. Prospecting here should await results of further 

In conclusion it may be said drilling east <;>f Cienaga C~yon. 

1. That a belt half a mile to a mile· in width 

on each side of the axis of the Pioneer anticline offers excellent promise of yielding light 

oil from sandy lenses in the upper shale membei' of the Vaqueros formation. 

2. That oil occurs seat tered through this 

shale practically ·from· the top to the bottom, 

but that most of the oil so far obtained has 

come from sandy beds in the lower part of the 

shale. 

3. That water sands occur scattered through 

the formation, but their position with relation 

to the oil-filled sand lenses is not known. In 

some of the wells water has been found both 

above and below the oil, and in some logs 

water and oil are reported.in the same sand. 

4. That the lenticular form of the porous 

beds and the lack of a pronounced unconforn1ity along which oil might migrate readily 

and near which it would tend to accumulate 

both indicate that the area will prove spottedthat the proportion of unsuccessful wells will 

be much higher than in the main part of the 

Sm~set-Midway field. 

OIL IN THE McKITTRICK GROUP. 

The general character and position of the 

McKittrick group in the east-central part of 

T. 11 N., R. 23 W., are much the same as along 

the foothills west of Taft. The beds· are alternating coarse sand and fine clay; they rest un-

.conformably upon the older formations; they 

lie on the flank of a small anticline that passe~ 

through the outermost ~oothills and plunges beneath the· Great Valley; an<l finally they show 

in their outcrop the presence of oil. 

Only a Jew general conclusions may be given 

as to the probable amount of oil in the basal 

McKittrick beds here, for the area is completely covered by alluvium, and no well that · 

is north of a Une drawn about S. 7 5° E. from the 

southwest corner of sec. 16 has been drilled 

deep enough to test the s,ands at the base of the 

group. 

The analogy between the conditions here 

and those on the west side of Midway Valley 

appears fa:irly close, and it seems reasonable 

to expect that the basal beds of the McKit-
150 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

trick group will yield oil in parts of secf3.15 and ·and in the northeastern _part of sec. 28 the 

16, the northeastern part of sec. 21, and parts McKittrick is probably too thin to have reof secs.\23 and 24. tained commercial amounts of oil. 

In certain ways,.however, this area appears 

less promising than the belt along the foothills 

west of. Midway Valley~ From what little evidence- the outcrops afford it seems probable 

that the dip of the oil-bearing zone is rather 

high, and that along the north edge of the area 

shown on the map· (Pl. XLIV) the bas.al beds 

of the McKittrick are. buried deeply, possibly 

too deeply to be reached by the drill. The 

supposition that the dip here is high is strength:-

ened by a consideration of the structure of the 

outer foqthills ·of the San · Emigdio Mountains 

east of Santiago Creek, for all along that part of 

the range the beds in the· outermost hills dip at 

a high angle to the north beneath the Great 

Valley. It therefore seems reasonable to suppose that in this area, which forms the west 

end of the San Emigdio Mountains and is thus 

the western extension of the belt just described, 

the beds likewise dip northward . at a fairly 

high angle .. 

It is possible, of · oourse, though the writer 

believes it highly Improbable, that beneath ·tJhe 

alluvial filling of the valley in the area north of 

the Pioneer anticline and south of -the Thirtyfive anticline the ~:~trata are folded, into an-

·other anticline. The beds much more probably _lie in a regular trough ·or syncline that 

separates the P1oneer and Thirty-five . anticlines and is the extension of the Phoenix 

syncline .. 

No well so far drilled has· really tested this 

area. The deep well of the El ·Camino Co. in 

sec. ·10 lies .on the north flank of the f:!yncli;Ue 

and virtually in the extension of the Thirtyfive anticline and affords no test of the strata 

lying between the axis of the Phoenix &yncline 

and· the southern edge of the McKittrick group. 

In conclusion it may be· said that· the prospect is good of obtaining heavy oil from the 

beds in the lower part of the McKittrick group, 

along a belt that extends from the vicinity of 

the west line of sec. 16, T. 11 N., R. 23 W., to 

the vicinity of the east line of that .township. 

The ~:Jouth 'line of this belt extends. from the 

vicinity of the southwest corner of sec. 16 to 

the vicinity of the southeast corner of sec. 22, 

eastward from which its oourse is probably al.:. 

·most due east for a mile more. In sec~ 21 south 

of this line, in the southwest corner of sec. 22, 

RUDISILL-BARNODON AREA. 

[Northeastern part of sec. 1, ').'. 31 S., R. 22 E.; southwestern part of sec. 5, sees. 6, 7, and 8, southwestern_ 

part of sec. 9, southwest corner of sec. 10, S. ! sec. 

14, all but northeast corner of sec. 15, sec. 16, all but 

southwe~t corner of sec. 17, N. ! sec. 18, T. 31 S., 

R. 23 E.] 

LOCATION AND WELLS. 

The . Rudisill-Barnodon area lies at the , 

extreme north end of the Buena Vista Hills, 

extending from the south end of the McKittrick 

field southward to the low divide which cuts 

through sees. 9 and 17 and divides the north 

Buena Vista Hills into two parts. There were · 

no producing wells in this area in 1916, nor 

were any wells being drilled at that time. 

Deep wells have been iliilled by the Union 

Oil Co. (Rudisill) in sec. 6; the Calanova, Rex 

Midway, and Mays Consolidated companies in 

sec. 8; the Standard Oil Co. · (four wells) in· 

sec. 16; and the Barnodon Oil Co. in .sec. 14. 

N on.e of these wells produced oil, and in 1916 

most of_ them were definitely a~andoned. 

GEOLOGY. 

This area lies on the two small folds, the 

Rudisill and £arnodon anticlines, which 

toge~her for:rp. the northern of the two zo'nes 

of upward folding that extend through the 

north half of the Buena Vista Hills. The 

general structure of this portion of the hills 

i~ discussed on pages 57-59. On the northeast the area is limited by ·the Buena Vista 

syncline, and on the southwest· by the shallow 

and irregular structural depression that separates the Rudisill and Barnodon anticlines 

from the southerly zone · of upward folding 

formed by the Globe and United anti~lines. 

. The beds along the Rudisill and Barnodon 

folds are tilted irregularly, locally to rather 

high angles, 40° or 50° being not uncommon. 

The folds are, however, clearly secondary features, being smaller than the folds that form 

the southerly zone of upward folding in the 

Buena Vista Hills-that is, the United, Globe, 

and Honolulu anticlines.· ·The Rudisill and 

Barnodon anticlines also evidently affect 'the 

strata to a less depth than the more southerly 

folds. An indication of the relative unimportance of th·e Barnodon fold is giv~n by the 
CALIDON-RECORD AREA.· 151_ 

position of the syncline that separates that anticline, just to the south, and in consequence 

fold from the United anticline, for, as shown a similar produ'ction was expected from· wells 

on Plates II and III, the syncline is much along the ~udisill and Barnodon anticlines. 

closer to the Barnodon anticline than to the Although these folds are not equal in size to the 

United anticline. The Barnodon and RudiE!ill United and Honolulu anticlines and are not so 

folds are therefore to be regarded as surficial isolated from the larger structural features, 

wrinkles in the flanks of a larger fold, much still they are large enough and sufficiently 

like the three small anticlines on the south isolated to make them appear very promising 

flank of the Elk I-iills. for the accumulation. of oil. Although the reT~le relative size of the Ba~nodon and Rudi- suits already obtained indicate that large flows 

sill anticlines is important in a consideration· of oil are apparently not to be expected in 

of the occurrence of petroleum, for here, just· tills area, it seems as if careful drillmg along 

as in the Elk I-Iills, the chief accumulations of these anticlines,. with systematic testing of the 

oil seen1 to be along the upper parts of the various sands which have been reported as 

larger folds, and, although the minor folds on "showing" oil, will result in wells which yield 

the flanks of the larger ones, when judged from a moderate amount of oil. 

the surface, appear to be excellent t:raps for 

the collection and holding of oil, in reality 

they do not extend deep enough to affect the 

oil-bearing measures to any great extent. 

OIL SANDS. 

Very little can be said regarding the occurrence of oil in this area. The wells that have 

so far been drilled have not been commercial 

successes, for although oil and gas are reported 

to have been found in most of them, the 

amounts are said to have been very small. 

It is probable, however, that if oil occurs 

within this area· in any considerable amount 

it is in beds that occupy a position equivalent 

to the C zone, which is productive in the 

southwestern part of T. 31 S., R. 23 E., just 

to the south. 

The McKittrick group, in which the chief 

producing oil.sands lie throughout the Midway 

district, thickens very greatly toward the 

northeast away from the main range. With 

the possible exception .of one of the wells 

drilled by the Standard Oil Co. in sec. 16 no 

well drilled in this area has completely penetrated the McKittrick group. In this area, 

just as in the area to the south, the sands 

that show the greatest amount of oil lie several 

hundred feet above the lowest beds in which 

sea shells are reported to occur, and it is evident that the chief oil sands are not along 

the plane of unconformity between the diato-. 

maceous l\1aricopa shale and the overlying· 

McKittrick. 

Many of the wells in this area were drilled 

when very large flows of oil were being obtained 

from wells along the axial part of the United· 

CALIDON-RECORD AREA. 

[Southeast corner of sec. 13, eas~ edge of ,sec. 24, northeast corner of sec. 25, T. 31 S., R. 22 E.; southwest 

corner of sec. 17, S. ! sec. 18, sees. 19, 20, and 21, all but 

north edge of sec. 22, western part of sec. 27, sec. 28, all 

but SW. i se.c. 2'9, N.! sec. 30, northeastern part of sec. 

33, northwest corner of sec. 34, T. 31 S., R. 23 E.] 

LOCATION AND OPERATORS. 

·The Calidon-Record area occupies the central 

part of the north half of the Buena Vista Hills, 

extending from the highway that . connects 

Taft and McKittrick eastward to the highest 

point in the north half of the hills. (See geologic section, Pl. XXIII.) The companies 

operating here in 1916 or controlling properties 

on which wells had been sunk prior to that 

date were the Midland Oilfields, Toronto Midway, Midway Royfll, General Petrol~um, Brook- , 

shire, Fairfield, Calidon, United, Kern Trading 

& Oil, Associated, Record, Consoliqated Mutual, 

Caribou, and Californian Amalgamated. 

GEOLOGY. 

This area lies on the west end of the more 

southerly of the two zones of upward folding 

which occupy the north half of the Buena 

Vista Hills. (See pp. 57-59.) The chief anticline here is the United anticline, which extends across the eastern part of th~ area and 

is a bro.ad, gently plunging fold, the beds dipping northward and southward away from the 

axis at very moderate angles. Close to the 

axis of the ·anticline the beds are in places 

tilted to angles of 15° to 20°, but the belt in 

which the beds are tilted as steeply as this does 

not extend more than a few hundred fee.t from 
152 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

the 1axis. Beyond the !i'mits of t~is belt the tained in the eastern part ofT. 31 S.·, R. 22 E., 

beds are ge~tly ..inclined, the angle of inclina- a11d near the center of the Midway syncline in 

tion being particularly low· on the north flank the vicinity of Taft. · The uppermost sand (the 

of the. anticline, where it is rarely more than B zone) which yields the oil in the southwest 

5~, and in many places the beds dip at an angle corner of T. 31 S., R. -23 E., and in the south 

less than the slope of the surface. The in- half of the Buena Vista Hills, apparently does 

clination of the beds on the south flank of the not contain oil in this part of the region, but 

fold is somewhat greater than on the north heavy flows of gas are reported in some of the· 

flank but even there is rarely more than 8° or wells at the horizon corresponding with the top 

10°. The inclination of 'the beds is shoWn in of the B zone. The wells in which gas was enthe geologic cross section forming Plate XXIII. countered at this horizon are chiefly along the 

Near the west end of the area the United anti- axis of the United anticline in the eastern part . 

cline piunges gently to the west, but the gene~al of the area. . · . 

zone of upward folding is continued westward ··It is difficult to obtain any very definite idea 

beyond the' limits of t~e area here described, of the character of the individual oil sands that 

by the Globe anticline. The saddle between make up the productive zone, for the logs rethe Globe and United anticlines is apparently . port." oil sand,"" sandy shale showing oil," etc., 

pretty well marked; the United anticline throughout a very thick zone,· and the beds 

plunges westward· at a very low angle, a~d .the reported as containing oil can not be correlated 

Globe anticline eastward at a somewha·t greater exactly with beds reported as being oil bearing 

angle. · in a well only a few hundred feet distant. It is 

Just east of the east end of the area the beds probable that the difference in the character of 

are folded into a number of small anticlines and the strata as reported in the logs of the wells is 

synclines-not, as in the west end, along a sin- more a difference in the drillers' interpretation . 

gle gentle upfold or anticline. As i~ explained . of the character of the beds penetrated thp.n a,n 

in the section of the report that described the actual difference in the lithology of the beds. 

structure of the Buena Vista Hills (p. 59), So many of the wells in this area have been 

these folds are in the main surface features, and drilled with rotary tools that the records are 

the beds at depths of 2;000 feet or so are not especially· unreliable, and about all that it is 

folded into regular wrinkles like the surface possible to do from these records is to correlate 

beds, but if bent at all are fashioned orily into the uppermost beds in the zone containing the 

structural benches. . productive oil sands. Plate L"'CIII is therefore 

OIL SANDS. 

rather less satisfactory than the other geologic 

sections (Pls. XVI-XXII, XXIV -XXXI), parThe chief oil sands in this area lie in the lower ticularly those showing Maricopa Flat, and the 

part of the McKittrick group, well within the division of the .productive zone into oil sands 

Etchegoin formation, for fossiliferous marine and barren strata shoWn in this section is very 

beds are reported 500 feet or more above the diagrammatic. 

top of the productive oil measures.· The sands Although the meagerness of the data given 

that have so far yielded oil, however, are not at f)y the records of the wells in this area precludes 

the base of .the Etchegoin, for in the deepest as detailed or accurate an analysis. of the char.:. 

wells marine fossils ·typical of the Etchegoin acter of the productive zone as can be made for 

are reported 600 ~eet or so below-the top of the other parts of the field, a few general features 

uppermost productive sands (the top of the C can be worked out, and these are discussed 

zone). With one possible e:xception no well has below .. 

:been drilled ·completely t~ough the Etchegoin. In the east end of the area alo:Ug the United 

The record of the single well, which may have· anticline the uppermost 100 ·or 150 feet of the 

been drilled deep enough to enter the unde:vlying producing zone (the C zone) is composed of 

diatomaceous Maricopa shale, does not give ·alternating sands containing oil and barren 

many data regarding the position of the top of clays, possibly 4_0 or 50 per cent of the whole 

the shale. containing oil. Below this is a thin water sand, 

The 'a~l sands extend through a. zone at least· underlying which are several irregular oil sands 

700 feet thick. The top of this zone is corre- . or sands containing gas that make up a zon~ 

lated with.the C zone, which:yields the oil ob- about 200 feet thick. A second wate~ sand lies 
CALIDON-RECORD AREA. 153 

just below these oil sands, its top being about 

300 or 350 feet below the top of the C zone. 

About 200 feet below this second water sand is 

the top of another series of producing oil sands, 

the lowermost producing oil sands yet encountered, which have yielded oil in several of the 

wells. These oil sands ·extend through a zone 

100 or perhaps 200 feet thick. Only one well 

has been drilled for any great ·distance below. 

these lower oil sands in the C zone, and its log 

records only water sands below this h~rizon. 

BEDS ABOVE THE PRODUCTIVE ZONE.· 

So many of the wells here were drilled, at 

least in part, with rotmy tools that the records 

of the upper parts of the holes are unreliable. 

Water is not.recorded in any well close to the 

top of the C zone. Gas is reported to occur 

in many of the wells at various horizons 

throughout a zone. that extends several hundred 

feet n.bove the top of the C zone and is said to 

be particuln.rly strong in wells nlong the crest 

of tho United nnticline in the eastern part of 

tho m·eo., ~ t tho horizon c9rresponding to the 

B zone of tho m·en. just to the east. Commercial 

flows. of gas have been obtained in. some of 

the wella from .strata at this hor~on. 

BEDS BELOW THE PRODUCTIVE ZONE. 

With a single posaible exception no well has 

been drilled deep enough to en tor the underlying diatomaceous Maricopa shale. The deep 

well was di·illed more than 1,400 feet below 

tho top of the C zone, and in the lower 700 feet 

only ·water so.nds and a· few sanda containing 

traces of oil o.nd gas were encountered~ These 

beds m·e apparently deepet· than any in which. 

marine· fossils· typical of tho Etchegoin formation have been found, and they may or may not 

be part of tho Maricopa shale. The diatomaceous shale is· buried so deeply throughout 

this m·eo., however, as to .make it unprofitable 

to drill for oil in it, for experience in the pm·ts 

of tho field o.long the foothills of' the main 

range where tho shale lies at shallower depths 

has shown that oil sands in the shale are very· 

lenticular o.nd tho.t they o.re usually. limited 

to tho axial pm·ts of the an ticline2. 

WATER SANDS. 

Top water.-Watm sands are no·t recorded 

close to tho top of the C zone in the log of any 

well in thia areo.. Mo.11y of the wells, however, 

wore drilled with rotary tools and their water 

strings were set close to t):te top 9f the C zone, 

so that even though the water· sands are not 

recorded it is possible and indeed probable that 

they occur pretty well down in the section, for 

wells drilled in the manner in which most of 

those in this area have been drilled would not 

show the poaition of these top-water sands. 

The water string has been setnear the top of· 

the C zone in so many of the wells that future 

work in this area will probably foJlow the same 

practice. 

Edge and bottom water.-Water 1 is recorded 

below the top of. the C zone in sec. 22, on the 

north flank of the United anticline.; in the 

southern and western parts of sec. 28, on the 

south flank of that fold; and also in sec. 20, 

near the west end of the United anticline. 

In the axial part of the fold in the northeastern 

part of sec. 28 many of the logs do not record 

water, yet water is troublesome there, being 

produced in considerable amount with the oil 

by many pf the wells, and it is probable that 

many wells in that vicinity have penetrated 

the water sand, which did not show much if 

any water ~hen the well first came in. 

The wells who.se logs record water are so 

scattered that it is difficult to make out juat' 

the position these water sands occupy in the 

section. It seems, however, that on the north 

flank of the fold there are two fairly well defined 

water sands, one lying about 100 or 150 feet 

below the top of the C zone and the other about 

200 feet deeper. Most of the wells .in this area 

derive their oil from the topmost beds in the 

C zone, and many of them do not penetrate the 

C zone deeply enough to enter the upper of 

these two water sands. These sands· are 

shown diagrammatically in Plate XXIII. In 

this section neither of the two :water sands i':! 

shown as extending to the crest of the Globe 

anticline, 'for although the lower one probably 

does extend that far its exact position may not 

be determined from the records of the wells sQ 

far drilled. The upper sand may not extend 

to the axis of the ~old but may be an edge-water 

sand for one of the producing oil sands higher 

in the fold. Each of the· sands, however, i':! a 

soutce of dange1 · to the producing oil sands 

till oughou t this area, for, even though water 

may; ·not now occupy the sand along the axial 

part of the United anticline it certainly. will 

work it.s way through when the oil is extracted. 

· 1 Sco analysis 5, Table 14, and apalyses 37, 38, and 39, Table 21, Part II' 

(Prof. Paper 117). · 
154 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

It is not poasible to correlate exactly the two 

water sands described above with the water 

sands that lie on the south flank of the United 

an tic line. The water sand (shown on Pl. 

XXIII) that lies low on the south flank of the 

fold is propably to.be correlated with the sand 

that yields large flowa of .salt water in sec. 32, 

· T. 31 S., R. 23 E., near the axia of the Midway 

Valley syncline. 

PRODUCTION. 

east-have been cased off with the water string. · 

It is therefore probable that in much of the 

area, particularly in sec. 28, in which the wells 

are fairly numerous, .the B zone is now occupied 

by water. 

Future .work in exploiting this area should 

be· concerned chieflyo with the. extraction of 

the oil from the C zone and particularly· with 

the proper handling of the water there. So 

many of· the wells have been drilled several 

The ·production of wells in this area varies 'hundred feet below the top of the C zone withconsiderably. In general the wells ·in the out making any attempt to ascertain the posi-

. western part of the area, near .the structur~l tion of the probable water sands in that zone or 

depression or saddle between the Globe and to case off portions of the zone in which water 

United anticlines, have not had an initial pro- might occur that a proper handling of the area 

duction of more than a few hundred barrels will be very difficult. The probable position 

Wells near the east end of the area in sees. 22, of the chief water sands is shown on Plate. 

27, and 28, near the crest of the United anti~ XXIII, and is discussed above. 

cline, have yielded great quantities-of oil flowing Deep drilling for possible producing oil sands 

several thousand barrels of oil daily when first in the diatomaceous Maricopa shale doos not 

drilled. . The gas pressure in much of this. area appear very promising, for this shale is buried 

has now been reduced very greatly, yet . the so deeply that prospecting by the drill for · 

wells drilled in 1916 have flowed several smali· lenses of oil sand such as are to be 

·hundred barrels daily, and wells of1ike cap·acity expected ill it will be. very expensive .. The 

can still be obtained. · wells that have so far been drilled indicate 

that the producing beds in the McKittrick 

CHARACTER OF THE OIL. 

Near the· western .edge of the area the oil 

obtained from the c zone is all of about· 20° 

to 23 o Baume. In the eastern part of the area, 

the crest of the United anticline, the oil ranges 

from about 22° to 30° Baum.e; the average 

·gravity is about 27° Baume. There seems to 

be no regular difference in the gravity of the 

oil obtained froni different parts of the productive zone, the deepest· .sands yielding oil no 

lighter than that obtained from the very uppermost sands of that zone. Wells that yield 

water pr.oduce here, as in other parts· of the 

district, somewhat heavier oil than wells- that 

are free from water. 

SUGGESTIONS FOR FUTURE WORK. 

Originally the B zone evidently contained 

.considerable gas in much if not all of this area. 

Commercial amounts of· gas ·have been· obtained from it in some of the wells, and probably 

even now some gas might be produced if that 

zone. were systematically' prospected. Many 

of the wells, however, have been. drilled to 

produce oil from only the C zone, and the upper 

beds-those that make up the B zone, which 

yields oil and gas in the area_ just to the south-. 

group (Etchegoin formation) extend 700 feet 

or so below the top of the C zone. Drilling · 

to that depth below the top of the c zone as 

shown on Plate 'III is worth while. 

McNEE-McLEOD AREA. 

[Southern part of sec. 23, southeastern part of sec. 25, 

sec. 26, southeastern part of sec. 27, all of sec. 34 except 

northwest corner, sees. 35 and 36, T. 31 S., R. 23 E.; 

southwest corner of sec. 31, T. 31 S., R. 24 E.; northwestern part of sec. 1, all of sec. 2 except southwest 

corner, northeastern part of sec. 3, T. 32 S., R. 23 E.] 

LOCATION AND OPERATORS. 

The McNee-McLeod area lies in the central 

part of the Buena Vista Hills, extending 

northwaid from. the pass that cuts through the 

hills near the southwest corner of T. 31 S., 

R. 23 E., and divides the hills into two parts 

to the highest point in the north. half of the 

Buena Vista Hills. It extends from the 

center o.f Midway Valley northeastward across 

the Buena Vista Hills to the southwestern 

edge of the Buena Vista'Valley. (See geologic 

sections, Pis. XXIV and XXV.) The companies operating here in 1916 were the Standard, 

AssoCiated, Union, Kern Trading & Oil, and 

North American Consolidated. 
McNEE-McLEOD AREA. 155 .. GEOLOGY. are bent into a fairly well defined though 

strqngly plunging anticline, whereas the beds 

The ch~ef structural feature in this area is at depths of 1,800 to 2,000 feet show only 

the United anticline, the east end of which .irregular flattening or benching. 

occupies the central part of the hills. This 

part of the anticline is ·rather different in or:L SANDs. 

character fr01n the west end or from the As in tlie other parts of the Buena Vista 

I-Ionolulu anticline, which occupies the south- _Hills the producing oil sands in this area lie 

ern half of the Buena Vista Hills, for instead entirely within the Etchegoin formation but 

of forming a simple arch, the beds in a belt not at the base of that formation. It is 

one-half to tbJ:ee-fourths of a mile in width ,probable that no well has yet 'penetrated all 

are bent into a number of sharp parallel the Etchegoin formation, for fossiliferous beds 

wrinkles. The difference in the structure in have· been ~ound at depths of 350 feet below 

this ·central part of the ·Buena Vista Hills the top of the C zone.- .The stratigraphically 

may be appreciated readily from an exami- deepest wells have penetrated beds that lie 

nation of the geologic map (Pl. II) or, still 500 or 600 feet below the top of the C zone. 

better, from an examination of th~ under- The lowest beds encountered in zone C are 

ground contour map (PL III). These small not fossiliferous, but to judge from tha results 

anti~lines and synclines all plunge sharply. obtained in the deep wells in the area just 

southeastward to the structural depression or west of this one these beds are also part of the 

saddle, in the southeast corner of sec. 36, tha.t Etchegoin forniation. 

separates the United and Honolulu anticlines. The uppern;tost producing sands in this area 

At the surface the beds are rather sharply are correlated with the B zone of the foothill 

tilted close to the axes of the s1nall folds, area west of Taft. This correlation is exceeddipping in many places, especially along the ingly rough, for the beds may not lie at preeastern .edge of this closely fold~d belt, at cisely the same horizon, but they lie a~ approxiangl,es of 30° to 40°. Excellent exposures of mately.the same distance above the top of the 

the beds in this belt are. shown in the sides C zone, ·which affords the only basis for correof the gulch that cuts through the· hills near lation across. the Midway Valley syncline. 

the southeast corner of sec. 36. · Below the top of the B zone oil sands have been 

All the folds flatteno at considerable depth, encountered at·various positions in a zone some . 

and beds that are buried 2,000 feet or so are 800 feet thick. Very few o'f the wells penetrate 

less sharply flexed than the surface beds. all of this zone, and most of them, particularly 

I-Iowever, even at that ·depth the beds are those that were drilled first, derive their oil 

folded. to a. noticeable degree, as is shown by from beds that lie no more than 200 or 300 

the contours drawn on the top of the produc- feet below the top of the B zone. 

ing oil zone (Pl. III). It is very difficult to make any exac·t division 

A detail of the· structure that is of lesser of this· producing .zone into two parts which 

ilnportance than the main upward folding but may be correlated with the B and C zones, for 

is still important in the consideration of the it is only along the outer edge-that is, away 

accumulation of oil is the flattening of the from the main closely folded belt near th~ axis 

dip, or the .formation of a structural bench, of the United anticline-that the upper sands 

in the northeast corner of sec. 34 and the (the B zone) become dry or contain water, 

northwestern part of sec. 35. As is ex- and the.chief productive sands lie in the lower 

plained in the· section dealing wi.th the struc- or C zone. . 

ture in the Buena Vista Hills (p. 58), this In sec. 36 all the folds plunge strongly 

irregular flattening of the dip is really to be toward the southeast, and in this part of the 

considered, together with a similar flattening area the upper orB zone contains oil. Northin sees. 1 and 6, as the northwestern exten- westward from sec. 36 the B zone contains less 

sion of the Sixteen an tic line. The difference and less oil and more and more gas. A very 

in the structure of the surface beds and that instructive section is given by the wells drilled 

of the beds which contain· oil is very n1arked along the axis of the most easterly of the antiin this part of the area, for the surface beds clines in the closely folded belt-that is, the 
156 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

fold that cuts through the center of sec. 26 

and plunges beneath the Buena Vista V~lley 

near the center of the east line of sec. 36. 

The sands that have yielded gas in great 

amounts in sec. 26 appear to be the sands that 

contain oil lower on the plunge o~ the fold in 

sees. 25 and 36. The same tendency for gas 

at about this horizon. The attempt bas -been 

made to produce gas in only one or two of the 

wells down the plunge of the fold, for in most 

of the wells gas is not recorded as being espe..; 

cially strong there. · 

WATER SANDS. 

to ·occupy the sands high on the anticline is . Top water.-Only a s~gle log has recorded 

shown by the ·sands where they lie along the water fairly_ close to the top of the B zone. 

axial part of. the main or United ·anticline, In this log a small water sand is recorded about 

which passes almost exactly through the north- 350 feet above the· top of that zone. Many of 

west corner of sec. 36. ·Even the sands which the wells have been drilled with rotary tools, 

form the uppermost part of the lower or C and no record has been kept of the upper water 

zone ap'pear to contain much-more gas and less sands, but it. is probable that, water actually 

oil in sec. 26 than down the plunge of the fold occurs close above the B zone in much of the · 

in sec. 36. . · . . . area, just as it does in other areas in the Mid-

!he.relation of the large.produc~g well~ m way district. There should,. however, be no 

th1s area to the st:ructure IS verY: mterestmg,' trouble in casing off til.e top water by setting 

for the large flowmg wells obtamed by the the water string fairly close to the top Gf the 

Standard Oil Co. in.sec. 36 appear to have no B zone: 

very definite r.elation t? the s~ver.al small folds, Bottom or edge water.-Records of the wells 

large wel1;i bemg _obtamed alike· In the .centers that have been drilled here are surprisingly free · 

of the sm~ll ~ynclines or alon~ the crests. of the from any mention of w;,ater with the oil sands·. 

small antiC~es. The ~elatwn noted ~ th.e F~rther northwest along the United anticline 

paragraph~ JUSt precedmg between the ml water is nvted at two or more horizons within 

sands low on the plunge of ~he folds ·and the the C zone, the B zone there not being pro due..; 

gas sands higher on the folds see~s to be the tive of oil. Very little wat8r, however, is rechief effect of th~ small~r structural features corded in.the logs of the deep wells which have 

on the accumulatiOn of oil. been drilled near the point where the United 

anticline plunges southward, in the central 

BEDS ABOVE THE PRODUCING OIL SANDS. ' parts of sees. 26 and 36. On the west side of 

Practically no well in this area, according to the Midway Valley syncline. very strong flows 

-the record, found water Close to the top of the of water are obtained fro~ a sand that lie~ 100 

B zone. Many of the wells, however,. were· feet or so below the top of the C zone, and this 

drilled with rotary tools, no recor4 being kept water sand has given a great deal of trouble in 

of the water sands above the point at which sec. 32, T. 31 S., R. 23 E. Its approximate 

the water string was set, and it is probable th~t PO!?ition is shown on Plate XXIV, and in more 

water occurs pretty close to the top of the B detail on· Plates XIX-XXI. It m~y be that 

· zone. The practice of setting the water string wa~er does not actual~y occupy th~ sand at this . 

close to the top of the oil sands has been honzon on the east side of the Midway Valley · 

followed so long that it is probable that the syncline, but as soon as the oil which now occugas sands lying above the top of the B zone pies that sand is removed the water will move 

can· not be handled co~mercially at present eastwar~ across the syncline and s~oner or later 

except perhaps in certain parts of the field appear m the wells that produce ml from the C 

where there are only a few wells. These sands zone in that ·part of the area. 

were of course mudded off in most wells but Too few wells have yet been drilled in the 

it is rather to be doubted whether the gas ;ands southwestern part of the area here discussedcan ever be ar~ificially so completely sealed as that is, near the axis o~ the Midway Valley synto retam the gas perfectly. cline-to permit any definite statements re-

. In many of the wells,. particularly those ~ gardll;lg the occurrence of water in the B zone.1 

sec. 26, gas was noted 200 to 300 feet above the From the conditions which prevail on the west 

top of the B zone, and some of the wells have side of the sJn.cline it seems almost certain that 

yielded COmmercial amounts of gas from beds 1 See analysis 43, Table 22, Part II (Prof. Paper 117) •. 
McNEE-M~LEOD AREA. 157 

the B zone is now and was originally occupied 

by water near the central part of the valley, 

well down toward the axis of the Midway Valley 

syncline. The wells that now depend upon the 

B zone-certain wells in sees. 35, 36, ap.d 2-

will probably be troubled by edge, water working eastward. 

In a similar way water which lies 100 feet or 

so below the top of the C zone in· sec. 32 will 

probably work eastward and appear in the wells 

near the southeas.t corner of T. 31 S., R. 23 E. 

The approximate position of this water sand is 

indicated on Plate XXIV. · 

The lack of water in sands interdigited with 

tho oil sands in this part of tho area is remarkable when this area is compared with other 

parts of the Midway Valley field, especially with 

Maricopa Flat. So many wells have been drilled 

without yielding much if any water with the oil 

that the original absence of such water seems to 

bo pretty well established. The fact is evident, 

however; that water occurs in the producing 

zone both near tho center of the Midway Valley 

syncline and on the west flank of that syncline. 

With tho extraction of oil from the area along 

tho United anticline this water is bound to work 

eastward and sooner or later to appear in the 

producing wells. 

Only three or four logs have recorded water 

'in tho C zone in this area. Tho water they record lies 200 to 400 feet below the top of the B 

zone and thus in a measure corresponds in position to the big water sand on the west flank 

of tho Midway Valley syncline in sec. 32, T. 31 

S., R. 23 E. Tho·wells whose logs record this 

sand lio on the east side of the closely folded 

bolt.near tho south end of tho United anticline, 

however, and tho wells between these wells 

which have found water and the Midway Valley 

syncline did not find water at this horizon. 

Therefore no definite correlation can be made 

between tho water sands in the two areas. 

PUODUCTION. 

Many of tho wells in this area had an exceptionally high production when first brought ·in, 

the initial rating of more than twenty of them 

being 1,000 barrels or more a day. An indication of tho richness of tlris part of tho district is 

shown by. tho record of production from sec. 36. 

According to tho published statement of the 

Standard Oil Co.1 'that section had produced 

prior to March 1, 1915, more than .10,000,000 

1 Stn.nclllrd Oil Bull., vol. 2, No. 11, March, 1915. 

barrels of oil, and at that time the daily production was about 11,500 barrels. The daily pro-

.duction has decreased somewhat, but up t~ 

July 1, ·1917, the section. had probably produced at least 7,000,000 barrels more oil. 

CHARACTER OF THE OIL. 

The oil in this area ranges in gravity from 

about 24 ° to a little ·more than 30° Baume. 

There seems to be a slight difference in grav-ity 

of oil obtained from the B zone and that obtained from the C zone. The difference, howev-er} is most marked in the outer edge of the 

belt in which the B zone is productiv-e, for 

there the B zone contains heav-ier oil than it 

does near the axial part of the anticline. The 

fact that the oil is heavier in that part of the 

area· is. probably due to the presence of edge 

water in the immediate 'Vicinity. · Although 

the difference in gravity of the oil is slight; it is 

usually a pretty fair guide, even in the axial 

part of the United anticline, as to the sand from 

which the oil is derived, for oil he.av-ier than 

25° Baume is pretty certain to come from the 

B zone. 

SUGG:ESTIONS FOR FUTURE WORK. 

This area is one of the richest in the whole 

district, many of the wells here hav-ing had an 

initial prod:uction of thousands of barrels 

daily. Part of the area, including sec. 36 and 

the parts of the sections bordering it on the 

north, west, and south, ~s now so. thoroughly 

drilled that the gas pressure is ev-idently 

greatly reduced, and, although some of the 

wells drilled in 1917 flowed more than 1,000 

barrels a day at first, it is not to be expected 

that so many large wells will be obtained here 

in future. It is safe, however, to predict that 

_a very great many of the wells t~ be drilled 

in this area will hav-e an initial production of 

se'Veral hundred barrels daily. The produeing 

sand is so thick here that the wells are fairly 

long-lived. · 

· The chief trouble to be expected here is the 

working eastward of edge water in both the B 

and C zones: This is discussed in some detail in 

the section describing the water sands (p. 156). 

This water can be handled properly only after a 

careful study is made of the history of the indiv-idual wells, and a systematic record kept of the, 

percentage of water made by each well. Sooner 

or later water will flood out the western part of 

the area and gradually ";.ork eastward up tho 
158 THE SUN:SET-MIDWAY OIL .FIELD, CALIF.-PART I. 

·dip to the axial part of the United anticline.· and simple· than in the southeast corner of 

Methods of retarding the mo'Vement of this T. 31 S., R. 23 E., just to the north, for the 

water or perhaps temporarily halting it can beds are bent into a. broad and regular elonbe worked out only if. such a record is a'Vailable. gated dome, with only a single small fold-the 

No well has yet reached the diatomaceous Sixteen anticline-to break its regularity. 

Maricopa shale, and that shale must lie buried The main fold, the Honolulu- anticline, is flatbeneath more than 3,000 feet of later Tertiary topped and in cross section along a northdeposits. Prospecting for lenses of oil sands eastward-trending line appears as a low arch. 

in the shale is therefore not a 'Very promising (See. fig. 8.) . The central part of the arch, 

commercial 'Venture, for it means ''Very deep where the beds dip at low angles, usually less 

drilling. The ·upper sand.s, _however, are so than 5°, forms a belt a mile or two. in width. 

filled with oil and- the upw~rd folding here is so Near the east end of the fold the central belt 

pronounced that it would seem that the chances of low dip is rather sharply outlined along a line 

for the occurrence of oil in the. lll;lderlying that extends from the vicinity of the center of 

shale arefairly good. . sec. 4 to the southeast corner-of sec. 2. South 

In other areas along the west side· of San of this line the beds dip at very moderate 

Joaquin Valley the diatomfl,ceous shale has angles, usually less than 5°; north of it they 

yielded oil in areas where it is strongly_ folded dip usually 10° to 15°. On the south flank of 

and has usually proved to be barren of oil the ~nticline -the change in dip is not so well 

wher~ .f9lding is more moderate. In other marked except near the northwest corner of 

words, . the producing sands or lenses in the sec. 7. . . . . 

diatomaceous .shale· seem to. be more closely The I-Ionolulu anticline plunges very ablimited to the axial parts of 'the anticline than ruptly northwestwa~d from the c~nter of sec. 6 

the .produ~tive oil sands in the later Tertiary to the structural depression or saddle in the 

beds. SE.l sec. 36, T. 31 S., R. 23 E., which separate~ 

. SOUTH HA:J;.F _OF BUENA VISTA J:IILLS. 

[South edges of sees. 31 to 34, T. 31 S., R. 24 E.;. southeastern part of sec. 1, north~astern part of sec. 12, T. 32 S., 

R. 23 E.; southwestern part of sec. 1, sees. 2 to 6, all 

but southwest corner of sec. 7, sees. 8 to 16, all but 

southwest corner· sec. 17, northeast corner of sec. 18, 

northeastern part of sec. 21, all but south edge of sec. 22, 

northern part'_of sec. 23, northwestern part of sec. 24, 

T. 32 S., R. 24 E.] 

LOCATION AND OPERATORS. 

_The portion of the Buena ·Vista Hills lying 

south of the pass which cuts through the hills 

near the southeast corner ofT. 31 S., R. 23 E., 

extends from the center of Midway Valley on 

the southwe$t to the edge of Buena Vista Valley. on the northeast and to Buena Vista Lake 

on the east.· . (See geologic section, Pl. XXVI.) 

The· ·companies operating here in 1916 were 

the Honolulu, St. Helens, Boston PaCific, General Petroleum, Standa~d, Kern Trading & Oil, 

Northern Exploration, Petroleum Midway 

(Ltd.),. Maricopa Investment, Schultz, and 

Luxor. · GEOLOGY. 

, This area occupies the south half of the 

more southerly of the two zones of upward 

folding that form the Buena Vista Hills. (See 

p. 59.) The folding here is. much more regular 

the Honolulu and United anticlines. It 

plunges eastward from the west line of sec. 10 

at a very moderate angle, about 2° to 5°. 

Between these two points the crest of the fold 

is approximately level. 

In the. south flank of the Honolulu anticline 

there is one main structural irregularity. This 

is the Sixteen anticline,· which is shown on 

Plate II as extending from the northeast corner of sec. 16, T. 32 S., R. 24 E., northwestward 

into sec. 2, T. 32 S., R. 23 E. This fold is not 

traceable throughout this distance, even in the 

surfac~ beds, for the topographic depr~ssion in 

sec. 8 prevel}ts the recognition of a connection. 

between the anticline in sees. 1 and 2 and that 

ill sec. 16, but it is probable that in the surface 

beds- these 'two folds are connected. The oil· 

sands.are, however, bent into an anticline only 

in sec. 16, for northwestward from that locality 

·the fold is expressed simply by a flattening 

of the dip- and the formation of a structural . 

bench or terrace. The difference in the structure of the beds that ·are exposed and the oilbearing sands, which are buried 2,000. to 3;000 

feet, may be appreciated by comparing the 

map·showing_the areal geology (Pl. II) and the 

map showing the structure of the oil sands 

(Pl. III). The structural depression or syncline that separates the Sixteen anticliJ?-e from 
SOUTH HALF OF BUENA V~STA HILLS. 159 

the larger I-Ionolulu anticline on the northeast 

is very shallow, and for all pract~cal purposes 

the beds may be considered as horizontal 

between the axes of the two anticlines. 

OIL SANDS. 

In this ar.ea, as in the ~orth half of the Buena 

Vista Hills, the producing oil sands lie :ln the 

l~tchegoin formation, for beds containing 

fossils typical of the Etchegoin are encouD:tered 

700 feet above the top of the C zone. The 

oil sn.nds do not, however, lie at the base of 

that formati.on, for beds containi~g Etchegoin 

fossils have been found in the central part of 

the area 700 feet below the top of the B zone 

and at the very east end of the Buena Vista 

I-Iills more than 1,000 feet below the top of the 

zone, :which is productive in the central part 

of the hills-that is, 'the B zone. 

The maximum thicknes~ of the zone ·con-;-

taining productive oil sands so f~r developed 

is about 700 feet. This thiclmess of the producing sands has been penetrated in the central part of the hills. The uppermost producing sand that has a considerable areal extent 

has been considered as "th~ top of the B zone, 

and its position is shown on the map (Pl. III). 

In certain parts of the area, particularly aiong 

the crest of the Sixteen anticline, sands or 

lenses containing oil are reported 100 or 150 

feet above the top of the B zone, and a few 

wells have produced some <?il from such lenses. 

These sands are shown diagrammatically in_ 

the geologir. section (Pl. XXVI). · 

On the flanks of the main fold the B zone is 

dry or contains gas in moderate or small 

amounts but no oil.. The part of the fold 

beneath which the B zone is productive is 

contained approximately in t~e area described 

above as the central- belt of low dip along the 

axis of the fold. · 

The bQds mapped as the C zone ar~h~e so~e~. 

what closer to the B zone than in other parts 

of the area, the distance between the top of the 

B zone and the top of the C zone being usually 

only 150 to 200 feet. 

llEDS ABOVE THE PH.ODUCTIVE ZONE. 

The beds 100 to 200 feet thick that rest upon 

the productive B zone in the central part of 

the I-Ionolulu anticline co~tain much gas under 

pressure-reported as originally 1,000 to 1,500 

pounds to the square inch in . many of the 

wells. In places ·thi's zone contains irregular 

lenses. of sand saturated with oil, but most of 

the we~ls which produce from this part of the 

sec.tion yield only dry gas. Besides the gas 

which occurs in this. zone gas is obtained in 

other sands .that are scattered throughout the 

upper part of the section. These sands are 

e.xtremely lenticular, and it is. difficult or impossible from the data furnished by the well 

logs to follow any of the g.as sands over much 

of th~ area. The uppermost gas sand noted 

lies only about 400 to 500 feet below the surface 

and was encountered in several wells, notably 

in Standard Oil Co. well No. 1, in sec. 16, and 

Honolulu Consolidated well No. ·3, in sec. 8. 

This sand is not under high pressure, however, 

and, although the Standard well is said to have 

made about 65,000,000 cubic .feet of gas daily, 

the pressure was only 24 pounds to the square 

inch, and the g~s was soon exhausted. 

BEDS BELOW THE PRODUCTIVE ZONE. 

It is doubtful whether.any of the wells drilled 

in this area have cmnpletely penetrated the 

Etchegoin formation and entered the underlying Maricopa shale. The two deepest wells in 

the central part of the area penetrated beds 

only 200 feet stratigraphically lower than the 

lowest. beds in which Etchegoin fossils have 

been reported. The lowest beds may or may 

not be part of the Maricopa shale. 

WATER SANDS. 

Top water._:__To::_:> water is not reported in any 

of the area close to the top of the B zone. The 

lowest top-water sand of which a reliable record 

is availabl~ lies about 300 feet above the top of 

the B zone/ and this is slightly above the top 

·of the zone containing dry gas. 

Bottom water.-On . the nor.th flank ·of the 

anticline a strong flow of· water was encountered in some of the wells about 200 or 250 feet 

below the top of the C zone.1 Water occupying 

a similar stratigraphic position was encountered in certain of the wells in the axial part 

of_' the Honolulu anticline, close to the point 

where th~ axis of that fold plunges .eastward. 

Water is also -reported to occur in this area last 

described at approximately the horizon qccupied by the top of the C zone.1 Along the axis· 

of the Si..xte~n anticline water has been encountered in one well about 250 feet below the 

top of the. C zone, but other wells along this 

anticline have penetrated the section· much 

1 Sec analyses 45-48, Table 22, Part ll (Prof. Paper 117). 
160 .. THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

more deeply, and their logs do not record water. 

It may be tha.t this water sand is very lenti-

.cular, b~t its occurrence at so many points in 

this part of the ·Buena Vista Hills indicates 

that it is more probably fairly persistent, or at 

least that there are a number of lenses at this 

horizon and that wells which penetrate the c 

zone more deeply than 200 feet should use 

particular care in te~ting for water at approximately 200 to 300 feet below the top of the C 

zone. (See Pl. XLV, A, B.) 

PRODUCTION. 

The original production .of many .of the wells 

in this area has been l.arge, for at least 24 of 

them have an initial daily production of more 

·than 1,000 ·barrels, and a somewhat greater 

number have produced at ·first between 400 and 

1,000 barrels. The two best producing wells 

in this area are Honolulu well No. 1, in sec. 8, 

T. 32 S., R.· 24 E., and ~ern .Trading & Oil Co. 

well No. 25, in sec. 1, T. 32 S., R. 23 E .. The 

Honolulu well commenced producing in October, 1911, and according to reports in the press 

yielded at first 5,000 barrels or more daily and 

during the first few, months averaged about 

2,000 barrels. This well is· said to have produced continuously. at a rate of 900 to 1,000 

barrels .daily up to at least January, 1916, and 

probably somewhat later. The Kern Trading 

& Oil Co. well. was brought in some time in 

January, 1916, and is sai<;i to have produced at 

a rate of 5,000 or. 6,000 barrels daily during the 

first 30 days. Its daily rating continU:ed to 

be more than 2,000 barrels during the next 18 

months. These two we~s are, of colirse, exceptionally large and steady producers,· but other 

wells that yielded a very large amount of oil 

daily have likewise shown a low rate of decrease. 

Many of the wells in the south half of the 

Buena Vista Hills have been drilled only to the 

gas sands that ove~lie the B zone, and these 

wells produce dry gas. It is chiefly from these 

wells and from the· wells in sees. 22 and 26, T. 

31 S., R. 23 E.~ in the north half of the Buena 

Vista Hills, that the line supplying Lo~ Angeles 

derive.d its gas in 1916. 

CHARACTER OF THE OIL. 

The oil obtained from the uppermost part of 

the productive zone-that is,. the .B zone-is 

slightly heavier than that obtained from-the 

lower sands of the C zone. Wells producing 

from the B zone yield oil of 22° to 27° Baume. 

Well$ producing entirely from the C.zone yield 

oil that ranges from about 25° to a little more 

than 31 ° Baume. Most of the wells produce 

oil from both zones, and the mixed oil is usually 

of less than 30° Baume. 

There is considerable variation· in the method 

of handling the wells, and the gravity of the oil 

produced appears 'to vary somewhat with the 

method of production-for example, according 

to whether or not the oil has. run through gas 

traps. Even the pressure maintained in the 

gas trap appears to have some effect upon the 

gravity of the oil. 

SUGGESTIONS FOR FUTURE WORK. 

This area contains greater reserves of petroleum than .. any other part of the Midway 

district, and although wells are fairly thick in 

certain portions of it-for instance, in sec~ 16-

most of the .area is still (1917) .sparsely drilled. 

Fortunately this part of the field is now in the 

hands of large operating companies, ·and it 

will be possible, if the legal status of.the fands 

is settled within a reasonable time, to formulate and follow some rational policy of development. · 

The drilling which . has so. far been done 

shows that a zone some 700 feet thick, the 

upper part of which is mapped in Plate III as 

the B .zone, . contains productive oil sands. 

Water has been found in this zone at one or 

two places-:-on the _north flank of the Honolulu anticline, near its east end, and in at 

least one well along the Sixteen anticline. 

This water lies approximately 600 feet below 

the top of the B zone. A:tthough it has not 

been recognized in many of the wells that have 

been .drilled to a greater depth, any well which 

goes deeper than 600 feet below the top of the 

B zone should test the sands carefully at that 

horizon for water. No well has yet gone 

through th~ Etchegoin formation and entered 

the diatomaceous Maricopa shale, and until 

that shale is reached the full thickness of the 

upper. productive zone is not penetrated. 

Down the plunge of the anticline the deep wells 

of the Pyramid Oil Co. have not passed through 

the entire thickness of the Etchegoin, but 

they have shown that the measures which 

contain oil higher on the fold are in this part of 

the area dry or contain only gas. 

Future work in this area. should be concerned chiefly with the effi.cient draining of the 

oil and ga8 sands so far recognized. Many of 
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 116 PLATE XLV 

A. 

B. 

A. B. CASING CORRODED BY WATER IN MIDWAY OIL FIELD. 

This casing was pulled from n well of the Honolulu Consolidated Oil Co. in the Buena Vista Hills. It had been in the well only about four 

years. Photographs b~ G. S. Rogers. 

C. SAND MADE BY WELL IN SUNSET FIELD. 

Well No. 13 of Adeline Consolidated Oil Co. View taken in October, 1908. Sand estimated to be about 110,000 cubic feet. Photograph by 

Ralph Arnold. 
SOUTHEASTERN PART OFT. 32 S., R. 24 E., AND OUTSKIRTS OF MARICOPA FLAT. :!_~1 

the operators disregard the gas sands that lie 

just above the B' zone, but as those sands are 

capable of yielding a very considerable amount 

of gas they should be exploited. The Honolulu 

Consolidated and Kern Trading &Oil companies 

are doing this in parts of the area. Along the 

axial part of the fold th~ B zone is productive, 

but. down the flank of the fold this zone 

probably contains water, although there is no 

record of it. in the well logs, and away from the 

axial part of the fold the C zone must be 

regarded as the probable productive zone. It 

is probable that the area lying on the flat top 

of the dome contains most of the really productive. oil land and that the S:rea from which 

much oil will be obtained lies within the area 

shown by contours on Plate III. . 

In this area, where the structure is so well 

marked and so regular, it is probable that the 

underlying diaton1aceous Maricopa shale is 

also strongly folded. It is ·along just such 

strong folds as these that in other areas, notably· in the Beh·idge-Lost Hills district, sandy 

lenses in the diat01;naceous shale contain commercial amounts of oil. When the sands in 

the Midway district that form the upper productive zone-that is, the sands in the Etchegoin formation-are drained, it will probably 

be found profitable to prospect the underlying 

diatomaceous shal~ along the Honolulu anticline. Such prospecting must, however, await 

the time when the price of oil is higher than at 

present and when the operators are prepared 

to take greater risks, for drilling for isolated 

lenses in the shale will always be costly, as the 

relative number of dry holes will be much 

larger than when drilling is done oruy for the 

upper and n1ore sheetlike sand of the Etchego~n. 

SOUTHEASTERN PART OF T. 32 S., R. 24 E., AND 

OUTSXlRTS OF :MARICOPA FLAT. 

SeveraldeepweUs,noneofwhichhaveobtained 

commercial amounts of oil, have been drilled in 

the southeastern part ofT. 32 S;, R. 24 E., in: 

the western part ofT. 32 S., R. 25 E., at the 

edge of the Buena Vista Hills; and in Maricopa 

Flat east and· south of the Thirty-five anticline. Some of these wells have been drilled 

deep enough to give the area a pretty thorough 

test; but others, although deep, have not been 

drilled deep enough to reach sands tha~ may 

possibly contain oil. 

109288°-19-11 

The wells of chief importance here are those 

of the Pyramid Co. in sec. 18, T. 32 S., R; 25 E; 

the Lakeview Annex in sec. 26, the Lakeview 

No. 2 Co. in sec. 26, and the Golden Gate Co. 

in sec.· 36, T. 32 S., R. 24 E.; the Comstock 

Crude in sec. 34, T. 12 N., R. ·23 W.; the El 

Camino in sec. 10, and the Bronco, Maricopa 

Producers, and Sunset Extension in. sec. 8, 

r. 11 N., R. 23 W. These wells are all situated 

low on 'the structural features that control the 

accumulation. of oil in this part of the fieldthe Honolulu and Thirty-five anticlines-and 

on the flank of the main range southeast of 

Sunset. 

It is impossible to predict, fron1 a consideration of the structure alone, the location of the 

boundaries ·of the area about one of these anticlines beneath which the sands contain commercial amounts of oil, for it is only by drilling 

that the limits of this area may be ascertained. 

It is possib_le, however, to indicate certain general features governing the occurrence of oil 

ill this area which may be of service in guiding 

test drilling. In considering the possible occurrence of oil in areas low on the flanks of these 

anticlines or near the axes of synclines it should 

always be remembered that the sands underlying such areas are deeper than those underlying areas along the axes of the anticlines, not 

only because the dip carries the beds that contain -oil along the anticlines to greater and 

greater depths toward the axes of the synclines, 

but also because of the fact that the oil, if 

present in the synclines, occurs in ·sands that 

are stratigraphically l~wer than the sands 

which contain oil along the anticlines. This 

fact, which has been mentioned again and again 

in the preceding pages, is excellently shown in 

Maricopa Flat, in sec. 32, T. 12 N., R. 23 W~ 

Even a cursory examination of the structural 

sections (Pis. XXVIII-XXX) will enable the 

reader to understand .the general position of 

the oil sands in the different parts of the folds. 

In the southeastern part ofT. 32 S., R. 24 E., 

to judge from the results obtained in wells along 

the south edge of the Buena Vista Hills and 

those northeast of Kerto, the upper sand-the 

B zone, which is contoured on Plate III-is 

dry or is occupied by water, and oil, if it underlies this area, is to be expected only from sands 

that lie below the top of the C zone, which is 

sh~wn by contours for t];le south end of the 
162 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

Buena Vista Hills, or below the flowing-water 

i;and that underlies Maricopa Flat. 

Two of the wells . in, this· area have been 

drilled about 500 or 6o"O feet below what appears 

to be the top of the C zone but have not found 

commercial amounts of oil. Neither have they 

completely penetrated the Etchegoin formation, for in the· stratigraphically deeper of the 

two wells fossils are reported .in the lowest ·beds 

penetrated. The well of the Golden Gate Co. 

in sec. 36 is of interest, as it lies.fairly close to 

the highly productive part of Maricopa Flat. 

This well is said to have been drilled to a depth 

of a little more than 4,000 feet. Apparently it 

was not drilled deep ~nough to reach the sands 

of the wells in sec. 8, however, reports fossil 

shells at a depth of about 900 feet below the oil 

sand believed to mark the top of the B zone. 

Were it not for this reported occurrence of 

fossils it would appear probable that these 

lower beds are actually part of the Maricopa 

shale, arid that the overlying McKittrick group 

is wedged out rather abruptly in this direction 

just as it is wedged out toward the west along 

the axis of the Thirty-five anticline. Most of 

the wells in sec. 8 have encountered heavy 

flows of saline water below the oily beds mar king 

the top of the J3 zone. The beds in the B zone 

here do not appear to contain. oil in commercial 

amounts. · 

that underlie the big flowing-water sand in sec. AREAS ADJACENT TO THE SUNSET-MIDWAY 

32. It shows, however, that the upper sand- FIELD. 

the B zone, contoured on Pla:te III-:-is dry in 

this part of the area. · 

The well of the El Camino Co. in sec. 10, 

T. 11 N., R. 23 W., .is said to have been drilled 

· · to a depth of 4,800 feet. This well is directly 

in line with the continuation of the Thirty-five 

anticline and therefore should give some idea 

as to the extent of the productive area along 

tllat.fold. If the anticline continues to plunge 

southeastward at the rate. it plunges iri sec. 4, 

the top of the B zone should 1ie at a depth of 

about 3,200 feet-about 1,000 feet deeper than 

it lies near the center of sec. 4. It is to be 

expected that this upper sand is dry so far 

down the plunge of the anticline, and that if 

oil occurs here it is in sands equivalent to those 

which underlie the sand that yields flowing 

. water in sees. 4 and 32-that is, in sands lying 

Certain areas lying within the region covered 

by the geologic map (Pl. II) but mainly outside 

the part of tha't region shown on the detailed 

map of the Sunset-Midway field (Pl. III) are 

prospective oil lands, but these areas are 

either still to be tested by the drill or are ttt 

present so sparsely drilled .that as detailed an 

analysis of the ch'aracter and position of the 

productive oil lands as is given in the preceding description of the productive fields can not 

be given for them~ The following paragraphs 

discuss the prospective value of these lands as 

judged chiefly from a consideration of the 

geologic structure as interpreted from the examination of the surface exposures. 

ELK mLLS. 

GEOLOGY • 

more than 500 feet below the top of the B zone. Broadly considered the structure of the Elk 

This well has apparently been drilled deep Hills is that of an anticline or dome, the highest 

enough to test the most promising sands if the part or axis of which trends southeastward 

stiuctureis regular between sees. 4 and 10. It from the vicinity of McKittrick to the north 

is quite possible, however, that the fault which end of Buena Vista Lake, passing through the 

trends northeastward along Cienaga Canyon highest part of the hills. In reality the struccontinues this far to the northeast and, inter- tlire is not that of a single fold, for there are a 

rupting the regularity of the structure, upsets number of anticlines and sjrnclines, but most 

the above calculation. ·of these folds are small and probably not deep, 

The wells in sec. 8, T. 11 N., R. 23 W .. , have and so far as the ~ccumulation of oil is conapparently been d~illed .deep enough. to en- ce~ned the effect of all of .them take~ together 

counter the upper sand which is productive is essentially the same as that of a single large 

, in Maricopa Flat (the B zone). The succes- upward fold. The central part of the area 

sion of beds penetrated by these wells below which this ·group of folds occupies-in other 

this sand believed to ·be the equivalent of the words, the central part of the Elk Hills-is 

top of the B zone resembles closely the sue- structurally the most favorable part for the 

cession of beds ·penetrated by the wells in -the accumulation of oil. The location of this 

vicinity of the town of Maricopa, which ·liave most favorable area may be described roughly 

entered the Maricopa shale. The log of one by saying that it forms a belt that extends for 
AREAS ADJACENT TO SUNSET-MIDWAY FIELD. 163 

a distance of a mile or so on each side of a line 

drawn from the vicinity of the southeast corner 

of sec. 34, .T. 30 S., R. 24 E., northwestward 

to the vicinity of the center of the south line of 

sec. 21, T. 30 S., B.. 23 E. The area thus described does not· necessarily include all the 

prospective oil land, but ·it is structurally the 

most promising part of the field and should be 

the part first to be tested. 

The producing oil sands in the Elk Hills lie 

in the Etchegoin formation and probably, 

like the oil sands in the Buena Vista Hills, are 

scattered through a zone several hundred feet" 

thick. Also as in the Buena Vista Hills the 

zone containing these oil sands is not neoe·ssarily at the base of the Etchegoin, for it seems 

probable that the sands which have yielded 

most of the oil in the Elk Hills lie several 

hundred feet above the top of· the diatomaceous shale that underlies the Etchegoin. 

graphically 1,000 feet below the uppermost 

Paso Robles beds that are exposed in the edge 

of the- hills. Fresh-water fossils are reported 

to have been found in these wells at. a depth of 

about 1,300 feet, below which lie 1,000 feet or 

beds from which no .fossils have been obtained 

and w4ich may be either part of the Etchegoin 

or part of the Paso Robles. At a depth of 

about 2,400 feet Etchegoin fossils have been 

obtained. From the data available it appears . 

that no well so far drilled in the Elk Hills has 

oompletely penetrated the Etohegt>in and 

entered the underlying Maricopa shale. 

WELLS DRILLED. 

The wells in the central part of the hills 

start in the Paso Robles formation stratiThe. following wells have been drilled in the 

Elk Hills. These wells are chiefly on the 

south slope and along the higher parts of the 

hills, in the belt noted above as being structurally the most favorable for .the accumulation of oil. · · 

Location. 

Quarter. Section. Township .. 

-·--------

SE. 20 30 

NE. 22 30 

sw. 22 30 

SE. 22 30 

NE. 24 30 

NW. 24 30 

sw. 24 30 

SE. 24 30 

sw. 26 30 

NW. 26 30 

NE. 26 30 

SE. 26 30 

sw. 28 30 

NE. so so 

sw. S2 so 

sw. so so 

SE. ·1 31 

SE. 2 S1 

NE. 10 S1 

SE. 11 S1 

NE. 13 Sl 

sw. . 14 31 

SE. 2 31 

SE. 3 31 

sw. 4 S1 

SE. 4 S1 

NE. 5 31 

NE. 7 31 

NK 8 S1 

sw. 9 S1 

NW. 10 S1 

SE. 11 S1 

NW. i2 31 

NE. 18 31 

SE. 18 31 

Range. 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

24 

23 

2S 

23 

23 

23 

23 

24 

24 

24 

24 

24 

24 

24 

24 

24 

24 

24 

24 

24 

Wells drilled in the Elk Hills. 

Company. Well Depth 

No. (feet). 

Scottish Oilfields Co ................................... · ............ . ABBociated Oil Co............................... . . . . . . . . . . . . 1 ..... do ........................... ·......................... '3 ..... do ......................................... ·............. , 4 ..... do..................................................... . . 1 

..... do..................................................... 2 

. .... do...................................................... 3 . .... do ......................................... :.......... 4 

. .... do.................................................... 1 ..... do.................................................... 2 

..... do .................................. ~........... .. .. .. 3, 

. .... do.................................................... 4 

Hillcrest Oil Co. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Redlands Oil Co ............................. ·. .. .. .. .. . .. .. . . 1 

Midway Pacific Oil Co..................................... 1 

ABBociated Oil Co.............................. .. .. ... .. .. .. 1 

F. J. Carmen....................................... . . . . . . . 1 

Combination Midway Co. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Mercedes Oil Co ......... ·...................... . . . . . . . . . . . . . 1 

Hart Oil Co ....... ~ ............... :........................ 2 

..... do.................................................... 1 

Barnodon Oil Co..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

East ~idway Oil Co ................................................ . Elk Hills M1dway Co.................................. .. .. .. 1 

Green & Hutchinson........................... . . . . . . . . . . . . . 1 

Section 4 Oil Co., or Potter, Reed & Taylor ........... ~., ........... . Associated Oil Co ................. : . . . . . . . . . . . . . . . . . . . . . . . . . · 1 

Elk Hills Oil Co ................................ ·. . . .. . . . . . . . 1 ..... do .................................................... · 1 

..... do .................. .' ....................... , .... ·..... 1 

General Petroleum Co................................. .. .. .. 1 

Monsoon Oil Co............... .. . . . .. . . . . .. .. .. .. .. .. . . . . . . . 1 

Midway Valley Oil Co .................... :...... .. .. .. . .. .. .. 1 

Kern Midway Oil Co.................... .. .. .. . .. .. .. .. .. . . 2 ..••. do ....•• _...................... . . . . . . . . . . . . . . . . . . . . . . . 1 

I 

4,005 

1,480 

2,980 

1,185 

70 

1,291 

3,887 

1,187 

4,030 

332 

518 

460 

1,670 

2,850 

2,450 

3,836 

745 

1,845 

1,800? 

2, 100± 

3, 650± 

3,208 

1,315 

1,415 

2,595 

1,400? 

2,128 

3,960 

2,260 

1,200? 

S,072 

1,205 

4:,850 

1,860 

250 
164 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

. .Of these -wells.-only a few have been drilled Petroleum well No. 1, in the NW. i sec. 10, T. 

:deep enough to give the area an adequate test. 31 S., R. 24 E., should be included in the third 

:·:The deep wells are listed below in three groups- group~ but it is not certain that they were 

:;:-(1) t~os~. which .~re along the belt most drilled deep enough to reach the horizon at 

,.favorable structurally fm:: the accumulation of which the Associated Oil wells encquntered oil. 

oil and which have ,obtained oil (2) one which The three wells listed above in group 1 have 

J?.as been drilled along this same belt but did not obtained considerable amounts of oil. In the 

·"obt~in oil, and. (3) ~hose which are not in the testimony submitted in the suit involving the 

··:most :favorable area. None of the wells in this lands in the Elk HiUs patented to the Southern 

>third.group has obtained oil. Pacific Co., the Associated Oil Co. admitted 

. :Group 1: the following production from these wells: 

SW. !sec. 24, T. 30 S., R. 23 E., Associated Oil Co. well Barrels. 

No. ·3. Well No.3, sec. 24, T. 30 S., R. 23 E ..... ·-----·--- 3, 602 

sW:!sec. 26, T. 30S., R. 23E., Associated Oil Co. well Well No.1, sec. 26, T. 30 S., R. 23 E ....... _______ 4, 074 

No.1. Well No.1, sec. 30, T. 3~ S., R. 24 E ...... ________ 2, 265 

SW. !sec. 30, T. 30S., R. 24E., Assodated Oil Co. well 

No.1. 9, 941 

Group 2.: · In the same c~se other testimony was sub- . · ·sE. t sec. 20, T. 30 S., R. 23 E.·, Scottish Oil Fields well. mitted to show that the amountof oil produced ·G~oup 3: , . h 

NE.! sec. 7, T. 31 s.; R. 24 E., Elk Hills Oil Co. well was somew at greater than this. 

No.1. · Below are the logs and history of two of the 

NW.! sec. 12, T. 31 S., R. 24 E., Midway Valley Oil- Associated well's in the Elk Hills. These records 

Co. well No. 1. are abstracted from the -testimony given by 

It is possible that Hart well No. 1 in the officers of· the Associated Oil Co. in the suit 

NE. i s~c. 13, T. 31 S., R. 23 E., and General mentioned above. 

Log of Associated Oil Co.'s wells in the Elk Hills. 

[From'daily drilling reports.] 

Well No. 1, sec. 30, T. 30 S., R. 24 E. 

Feet. 

0- 130 

130- 152 

.152.:.. 186 

SUrface. 

Brown sandy·shale. 

Blue sandy shale. 

Blue sand. 

Blue sandy shale. 

St~rted July 29, 1914. 

186- 230 

230- 300 

300- 315 

315- 390 

Blue clay. Small amount of gas evident. 

Blue sandy shale. 344-390, small amount 

of gas evident. 

. 390- 4;15 Sand. Some gas. 

415- 455· Blue clay. Landed 431 feet of 16-inch S. P. 

455- 472 Blue clay. 

. 472- · 515 ~lue sandy shale. 

·.51~ 520 Sand. · Gas. 

52()- 565 Blue sandy shale. 

)~f3~ : 572 Sand. 

5~2- ··600 Blue clay. 

600-· 605 Hard sand rock. 

605-- · 665 Blq.e clay. 

665- 712 Hard rock. 

712- '775 Blue clay. 

-775- , 8oo · Shell. 

800..: -. 805 Blue clay. 

801Y- · 808 Shell. 

808- 860 Blue clay . 

. 860- . 865 Shell. 

· .. : .. 865- t990 Blue clay. 

990-1;105 Blue shale. 

1,105-1,140 Blue clay. Landed 12!-inch at 1,129. 

1,140-1,150 Blue clay. 

Feet. 

1,150-1,208 Blue shale. 

1,208-1,280 Blue clay. 

1,280-1,285 Blue shale. 

1,285-1,290 · Shell. 

1,290-1,310 Blue shale. Lost bailer, tri'ed to drill up; 

finally sh~t it. 

1,310-1,323 Blue shale and iron. Pulled 10 inches and 

rigged up for rotary at 1,323. Took from 

December 11, 1910, to March 25, 1911, to· 

get ready for starting with rotary. · 

.1,323-1,412 Blue shale . 

1,412-1,417 Rock. 

·1,417-1,503 Blu.e clay. 

1,503-1,509. Rock. 

1,"50~1,726 Blue shale. 

J,726-1,730 Blue clay. 

1, 730-1,800 Blue shale. 

1,800-1,849 Blue clay. 

1,84g..:.1,853 Shell. 

1,853-1,868 Blue shale. 

1,868-1,880 Blue clay. 

1,880-1,98~ Blue shale. 

1,98~2,002 Blue clay. 

2,002-2,005 Shell. 

2,005-2,023 Blue clay . 

. 2,023-2,066 Clay and boulders. 

2,066-2,100 . Sand rock. 

2,100-2,125 Blue shale. 

2,125-2,200 Shale and boulders. 
AREAS ADJACENT TO SUNSET-MIDWAY FIELD •. 165. 

Feet. Feet. 

2,200-2,275 

2,275-2,280 

2,280-2,300 

2,300:--2,338 

2,338-2,310 

2,340-2,390 

2,390-2,408 

2,408-2,416 

2,416-2,423 

2,423-2,426 

Blue clay. 

Hard shale. 

Blue shale. 

Hard blue shale. 

Blue clay. 

_2, 711-2,713 Hard oil sand showing lots of oil, light in. 

gravity. 

In starting to· wash mud out of hole, the hole 

was found to be over o~e-half £till of solid 

. oil. Well' made so ·mu~h gas that it.is :q.ot· 

Hard blue s~1ale. 

Hard sand shell. 

Hard blue clay. 

Blue clay. 

· . advisable to complete washing or· drilli:p.g 

further liPtli iines insta(led. to take ca~e of 

production. Washed and then: resumed 

work with 4~inch drill. · · ' .. 

2,426-2,440 

2,440-2,452 

2,452-2,458 

2,458-2,465 

2,465-2,470 

2,470-2,471 

2,471-2,508 

2,508-2,580 

Hard brown shale and sea shells. Must be 

blue shale. 

J:Iard brown shale. 

Blue shale. 

Sand shell. 

Brown shale. 

Biue shale. 

Hard san'dy shale showing light oil and gas. 

Blue shale. 

Hard blue· shale. Very gritty, 2,520-2,529. 

At 2,580 reduced size of hole from 12! to 8 

inches to test.ahead for any oil or water 

before setting 8-inch ca.~ing for water shut 

off. 

2, 713-2,722 Oil sand. 

2,722-2,8iO Blue shale. 

2,810-2,819 Soft sandy shale. 

2,819-3,058 Shale, showing some oil. 

3,058-3,147. Blue shale. 

3,147-3,151 Shell:· · 

3,151-3,.234 Blue shaie. 

3,234-3,244 Sheli.' · 

3,244-3,384 Sandy shale; 

3,384-3,386 Shell. 

3,386-3,572 Blue shale.-

3,572-3,583 Sandy shale. 

3,583-3,705 Blue shale. St-inch at 2, 711. 

3,705-3,720 Rock. 

I • 1• [' 

3,720-3,836 Blue shale. 6t-inch at 3,836·. ; : 

2,580-2,635 

2,635-2,640 

2,640-2,710 

2, 710-2,711 

t.Hue shale. 

Hard blue shale. 

Soft blue shale and Good 

showing of oil. Eight-inch· casing landed 

at 2, 711 on what might be termed cap rock. 

Sand shell. 

Water bailed to 2,100 from surface; after test· 

o{ 24 hours no water enters hole. Flo~g. 

20 barrels per day between 6-inch and 8-

inch casings. Well perforated, 3,470 to. 

2, 730, three holes per foot; 2, 730 to 2,690~ 

four hole~ per foot. 

lliSTORY OF WELL. 

Jan. 22, 1912. Well on pump at 236. Pumped water for·three hours; then turned to oil. Showe~ pro~uction at, 

rate of 350 barrels for 18 hours; no water, 9 per cent B. S. 

Jan. 23. Production at rat~ of 350 barrels. Gravity, 26.4; 4/10 :vat~r, 2.2 B. S. 

Date. Oil (barrels). B.S. Water Gravi~y. (per cent). (per cent). Remarks: 

':# 

1912. 

400 gage. . . . . . . . . . . . . . . . . . . . . . . . . 24. 5 6 2. 1 . . ! ! ·. 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ·Rods parted. · · ................................................................ On pump at 11 p.m . .- 400............................. 25 ...................... . 

Jan. · .24 

25 

26 

27 

28 

29 

30 

31 

· 2i2 ·r~;t~:::::::::::::::::::: :·:::: · · · · · 25 · · ~ :::::::::: ::: :.:::::: Pulled tubing, on pump at.~dnight. 90 ......................... ·..... 25 ................... . 

Feb. 1 . ~-~~::::::::::::::::::::: ·:::::::: ..... .'~~ ~ .. : :·: :·:::::: ::::::::::: Rods parted. . : · . 

2 300 rnte......................... 25 ..... · ................ On pump 5 p.m .. 3 

4 

5 

6 

7 

8 

9 

72 ........................ •.•.... . 25 ...................... . 72 ............................ , .. ' 25 ................... . 53 .......................... -... 25 ...................... . 53.............................. 25 ................... . 50.............................. 22.6 .................... . 

50 ................. ~---······•·· 22.6 ·········· ......... . 50 ................ :.............. 22.6 ·········· .......... . 1.0-15 

16-28 

29 120. ;.'. ........ ,· . . . . . . . . . . . . . . . . . . . ·. . . . . . . . . . . . . . . . . . . ........ . Mar. 1 75 ............................................................ . 2 50 ......................................................... · .. . 3 50 ........................................................... . 4 50 ............................................... '''.: ... : .•.. 5 

Swabb~g and sand pu~ping::- .; . P.erforation 2,800.:.2,650 .. Swa:b bed, et~ · 

To get. oil to flood well. 

Flooded well with 250 barrels of. oil •. Pressure ran up to 180 pounds. 
166 THE' SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. • 

HISTORY OF WELL_:_continued. 

Date. Oil (barrels). G 't B. S. Water 

raVI Y· (per cent). (per cent). Remarks. 

1912. 

Mar. 6 200.· .......................................................... Well no better than before flooding. 

7 

8 

9 

10 

11 

12 

13 

14 

.................. · ....... , . , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Put in ne'v pump. ................................. .......... .......... .......... Do. 

. ~g~ ~r~~~ ~ : : : ·: : : : : : : : .: ·: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : J 

Do. 

••••........•.....•••... .' .........•••..••..• ••...... : • ...•...... 1 

50.0 0 0 0 0 0 0 _._ 0 0 0 0 0 0 0. 0 0 0 0 0 0 ;, 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .·• 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .i •••••.•••••••••••••••••••••••• ~ • • • • • • • • • • • • • • • • . . • • • • • ••••••••• ! Pulling rods, etc. 

15-17 Do. 

18 

19 

20 

21 

22 

23 

24 

25' 

26 

27 

28 

29 

30 

31 

· i5o ·r·a·t~- £~; i2 -h~~~~---·_·_ ~::::::::: :.::::::::: :::::::::: :-:::::::: :\ 

0 ~~: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :·: : : ·: : : : ~ : : : : : : : : : : l ~d~~~~~x.er cent water 0 

................................. .......... .......... .......... ·Do. 

AJ>r.. 1 

.2 

3 

4 

5 

6 

50 •..•...•...••....•....... ··••• 0 ......... 0 .••••...... 0 ······· 45.0 0 0 0 0 0 0 0 0 •..•.•. 0 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 •. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .... 0 0 0 

45.0 0 0 0 0 0 0 0 0 0. 0 0. 0 0 ·-· 0 0 0 0 0 0 0 0 0 0 0 0 -~ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

!~::::: ::::::::::::::::::::::::::::::::::: ::::::::::::::::::::1 

45. "···· 0 •.. 0. 0 ...••.. 0. 0. 0 .· •.. 0 0 .. 0 ... 0.' .. 0 .. 0 0 0 0 0 0 0. 0 ....•• 0 

35.0. 0 0 0 ••• 0 0. 0, 0 0 0 0 0 .... 0 0 0 0 0 0. : ~ 0 0 0 0 0. 0 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0. 

45.0 0 ~ 0. 0 0 0 0 0. 0 0. 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 0 0 0 0 0 0 0 

40. ··•··•···•··•···•·•····· ...••• 0 ········· 0 ........ 0 0 0 0 0 0 0 ...•• 40.0 0 0 0 0. ·.•· 0 0 0 0 0 0 0 0 .. 0 0 0 0 0 .. 0 0. 0 0 0 0 0 0 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 .. ·. 0 0 0 00 0 

. ~g: ~ : : ~ : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : ~ : : : : : : : : : : : 

4o .. :· ..... :.: ................. :. 25 4-fl> ·n 

40.0 ... ·; 0. ~ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 •.• 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0. 0 0 0:0 0 0 0 

40.0 0 0 0 0. 0 •.• :··.· ~ 0 0:0 0 0 0 0 0 0 0 0 0 0 0 0 0 ·.· 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 0 0 0 0 0 

35.0 0 0 0 ••.. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 0 0 0 0 .. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

7 ........................ ~ ..................... , ................ Rods parted. 

8-18 ............................................................... Idle. 

19 On pump at 3 p. m. 20 ··4o:: :~:<·:·: :·::::::::::::::::::::::: ·::: >: ~::~!::: ~: ·:: :<-: ·::: :::::::::: 

~~ ~g: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : ·::: :< : : : : : : : : . l. 

23 35 •• 0 0 0 0 0 0 0 0 0 0. 0 0 0 0. 0 0 0 0 0 0. 0 0 0 .-. 0 0 0. 0 0 0 ••. 0 ..... 0 •... 0 0 0 0 0 0 0 •. 

24 25 ••.•• 0 0 .. ·. 0 0 0 0 0 •. 0 0 •. 0 0 0 0 0 0 0 •• 0 •. 0 0 0 0 ..•. 0 0 .·. 0 0 0 0 0 0 0 0 0 0 •. 0. 0 

25 25. ,',-._ •.•.•• ·.; 0 0 .•.• 0. 0 0 0. 0. •.• 0.: •·• 0 0 0 0 0 0. 0 0 0 0 0 0 0:.0 0 -·~ • '. 0 .... 0 ••• A 26-} . . ·· ~ ~~ 3 . 25 barrels oil per day pumped .............. : ............ _ ..... .. 

May 4 . 25 barrels oil and water .... : .................................. . 5 ..... do ...................... : ................................ . 6 20 barrels oil and water ...................... , ............... .. 7 16 barrels oil and water .................... ~ ................. ~ . 8 15 barrels oil and water ........ : ............................. .. 9 20 barrels oil and water ......................... · .............. ·. "10 ••••• do ..... :; •: •... _. .... : . . . . . . . . . . . . . . . . . . . . . . ...... · .. · . . ......... 1 

13--~! .~::::: :::: ::::,:_:_::::::::::::::::: :·::::::::::::::: ] ...... -~~. Rods parted, idle. 

27 30 •••• •.•. 0 •• 0 •... .'.·. 0 0 ••• 0 0. 0 0 0. 0 •• ~ 0 •• 0 ••• 0. 0 0 .· .. 0 ••. 0 0. 0 0 0 0. 0 

~~ :g:::::::·~::·::::~::·:::~::::::::.: ·:::::::::~ -:::::::::: :::~~~~~:1 31 20 •••••••• · ................................................. do ... l 

June 1 10. • . • . • • • . • . . . • . • • . • • . • • • • . • . • . • ..••••••.••.•. : • • • • . • •. . . . . . . . Rods parted. 

~ . 3o: : : : : : : : : : : : : : : ·: : : : : : : : : : : : : : :· : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :, Do. 

4 30 ••...•.•.......•.•.•.•.••.•..• ••·•·••••• ••......••.•.....•.• 5-8 •••.•...•.•.•. ·. ; ..••• ~., •.••.••......•.•..•• ·- ..•••••••.••... 0 • Idle. 

9 20 •• 0 0 0. 0. 0. 0' 0 . • ::" ••.•• 0 0 ... 0 0 0. 0 0. 0. 0 0. 0 0 0 0 0::.0 0. 0 0. 0 0 0 0 0. 0 0 0 

10 •.•••.•........•.•..••...••..•.....••.••..•••••..•.......... 0. • Pnt on pump. · 11 30 •• 0 •• ~ 0 0 0 0 0 _. 0 0 0 • 0 0 · .• _. ~ 0 • 0 0 0 0 0 0 0 0 0 • 0 . 0 0 • • • •• 0 ' 0 0 . 0 0 • 0 0 0 0 0 0 0 0 0 

12 30 .•.• 0 •• 0 0 0 0 0 0 .. 0 0 0 0 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 0 .· .. 0 0. 0 0 0. 0 0 0 0 0 0 0 0 0 0 0 0 ... 13 20 ••.••. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 •.• 0 0 0 0:. 0 0 0 0 0 0 0. 0 0 0 0 0 0 •• 0 0 0 0 0 0 0 0 0 0 0 ooo 

14 20.0 ... 0 0 0 0 0 0 0 0 0 0 0 0 0 .. 0 0 0 0 0 0 .• 0 0 0 0 0 0 0 0 •. 0 0 0 0 0 0 0 •• 0:0 0 0 0 0 0 0 0 0 .. 0. 

15 20.0 0. 0 ••••••• 0 0 0 0 0 0. 0 0 0 •• 0 0 0 0 0 0 0 •· ••••••••• 0 0 0 0 ••••• 0:0 0 0 0 0 0 0 0 

... 

~~i; i~- }.:. ~ ..... ·: ... · ...................... ~ ... · ....................... Rods parted. 

July 13 ................................................................ Put on pump; pumping water. 

14 30. 0 0 0 0 0 0 ••• 0. 0 ••• 0 0 0 0 0 •· 0 .• 0 0 0 0 0 • 0 0 0 0 ••• 0 0 • 0 0 0 0 0 0 0 0 0 50 

15 20 0 · •.• 0 0 0 0 • 0 0 ' 0 0 0 0 0 . 0 0 0 0 0 0 0 ' 0 0 0 0 0 0 0 0 0 0 0 0 . 0 0 • 0 0 0 0 0 0 0 0 0 50 
AREAS A:OJACENT TO SUNSET.,.MIDWAY FIELD. 167 

HISTORY OF WELL-COntinued. 

Date. Oil (barrels). Gravity. B. S. Water 

(per cent). (per cent). Remarks. 

1912. 

July 16 

17 

18 

19 

20 

30 .......... :................... . . . . . . . . . . . . . . . . . . . . 50 

35 .................... '............................. 90 

40............................... .. .. . . . . . . . .. . . . .. . 50 

· 35: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : ....... 25 ~ Placed on pump. \ 21-25 

26 

27 

28 

29 

30 

31 

·5o::::::::::::::::::::::::::::::::::::::::::::::::::······ ·5o· Rods parted. 

20.............................. . . . . . . . . . . . . . . . . . . . . a 20 

30 .................................... , . . . . . . . . . . . . . a 10 

20.............................. . . . . . . . . . . . . . . . . . . . . a 1.0 

27.................................................. a 9 

34 ............................... .' .. : ............... ·. a 31 

Aug. 1 14 ......................... · ......... ~...... . . . . . . . . . . a 12 

2 

3 

4 

15 ..................... , .... ·.... . . . . . . . . . . . . . . . . . . . . a 10 

14 ........................... :.. . . . . . . . . . . . . . . . . . . . . a 12 

···························.······ ·········· ·····.····· .......... . Rods parted. Off production ·and 

shut down on Aug. 23, 1912.' 

a Barrels. · 

Well No. 1, sec. 26, T. 30 S., R: 23 E. (rota..Y). 

Feet. 

0-1,086 Surface, shale, rock, houlders, etc. 

1.,086-1,095 Shale; some gas. 

1,095-1,657 Shale, gumbo, rock, etc., 10-inch, at 1,6~7. 

1,657-1,673 Rock. 

1,673-~,090 Shale and guinho. 

2,090-2,094 Rock. 

2,0fl4-2,162 Gumbo. 

2,162-2,210 Shale, with sen. shells .. 

2,210-2,235 Rock. 

2,235-2,285 · Gumbo. 

2,285-2,432 Blue shale and sea shells. 

2,432-2,548 Brown shale and sea !:!hells. 

2,548-2,562 Gumbo. 

2,562-2,590 Hard shale and rock. 

2,5fl0>-2,800 Shale and gumbo. 

2,800-2,802 Rock. 

2,802-2,811 Gumbo. 6J-inch casing, at 2,811. · 

'2,811-2,813 Gumbo. 

2,813-2,875 Sandy shale. 

2,875-3,050 Shale and gumbo. 

3,0n0-3,052 Rock. 

3,052-3,138 Shale anrl gumbo. 

3,138-3,143 Slui.le. 

3,143-3, l45 Rock. 

3,145-3,175 Shale and gumbo. Rigging. up for Standard 

tools. 4rinch casing.s~t at 3,168. 220 feet 

of 4!-inch perforated.. Put .rota.ry ba~k. 

3,177-3,226 Blue shale and gumbo. · 

3,226-3,241 'liard shale. 

3,241-3,243 Shell. 

. 3,243-3,259 Soft blue shale. 

3,259-3,263 Hard rock. 

3,263-3,268 Blue shale and gumbo: 

3,268-3,280 Hard blue shale. 

3,280-3,342 Soft blue shale and gumbo. 

3,342-3,360 Shale and shell. 

3,360-3,361 Rock. 

3,361.-3,387 liard blue shale. 

3,387-3,407 Sanely shale. 

3,·107-3,408 Hard rock. 

Feet. 

3,-108-3,414 Hard blue shale. 

3,414-3,548 Shale and gumbo. 

After washing niud out of hole and washing 

oil formation at 3,342-3,485 with drill 

pipe, pulled drill pipe out of hole. As 

last of pipe came out of hole ~us blew 

nearly all water out, standing at so· fee 

above derrick. Hole bridged at ·2,640. 

White bridge in well.· Flowed twice of its 

own accord and once from agitation with 

bailer, probably 2 or 3 barrels each time. 

Set 3-inch line pipe, 3,104-3,54R. Perforated it up to 3,30~. 

HISTORY OF WELT,, 

March 25, 1911. Well pumped some water, aiso flowed. 

Produced about 75 barrels oil. 

March 29. Tried to put on air. Pr.oduction 10 a. m. 

March 29 to 7 a. m. March 31 was 90 barrels oil, 9 

· barrels water. 

March 31. W<:ll on air at 3,051 feet. Production, .20· 

barrels day of oil, no water. · · 

Cut 4!-inch pipe at 2,880. Left casing in hole: 4!-inch, 

2,837-3,168; 3-inch, 3,104-3,548. 

.REDRILLING AND DE~PENING. 

On redrill a show of oil is noted at 3,140. [Record of redrill to 3,548 feet not copied.] 

3;550-3,!571· Blue shale and sheilA. 

3,571-3,575· Shale and gumbo. 4~-inch casing, at 3,571. 

3,575-3,580· Blue shale. 

3,b80-3,593 Blue shale showing heavy oil.· 

3,5!>3-3~596 · Compact sa.nd. 

3,596-3,609 · Hard shale and. gumbo. 

3,609-3,615 . Soft blue shale. 

3,615-3,619. Hard blue shale. 

3,619-3,622 Gumbo. . 

3,622-3,637. Hard blue shale. 

3,637-3,642 . Soft blue shale. 

3,642-3,651 Hard blue shale. 

3,651-3,657 Soft blue shale. 

3,657-3,664 Hard blue shale. 
lCS THE. $UNSET-MIDWAY. OIL FI$LD, CALIF.-PART I. 

Feet. 

3,664-3,666 - Hard sand.. Very light trace of oil all through 

1911. 

July 30·. Pumped 24. barrels; 9 barrels water. 

3,657-3,686. 31. Pumped 21 barrels; 3 barrels water. 

3,666-3,686 Hard blue shale. Also in soft shale 3,609- Aug. 1. Pumped 27 barrels; 3 barrels water. 

3657. . . .. 

3,686-3,708 Hard blue shale. 

3, 708-3,724 Shale and hard sand. 

3, 724-3,725 Shale and hard s~nd, showi.J).g oil. 

3,746 

3, 746-3,806 

3,806-3,848 

3,848-3,850 

3,850-3,857 

3' 85 7-3' 858 

3,858-3,859 

3,859-3,860 

'3,860-3,865 

3,865-3,918 

3,918-3,919 

3,919-3,'971 

3,971-3,974 

3,974-3,996 

3,996-4,000 

Shell. 

Hard.blue shale. : 

Firm blue shale, showing all light oil. 

Hard blue. shale; shows oil. 

Sand rock. 

Blue· shale. 

Blue shale, showing oil and more gas than it 

has ever shown. 

Hard shale, showing gas. 

Hard sand shell, showing gas and oil. 

Oil sand; shows 'QP good light oil. 

Oil sand; shows good. 

Hard shale. 

Oil sand. 

Sand shell. 

Oil sand. 

Hard blue shale; showed oil sand and could 

only be distinguished by drilling.-

. 4,000-4,030 Oil sand. 

At 4,030 encountered hard formation which 

could not be recognized on account of large 

quantity of sand running in from above. 

4,-inch. casing at 3,572. 3-inch perforated liner at 4,000 

feet. Top of liner at 3,498: 

. HISTORY OF WELL. 

July 31, 1911. Put on air at 2,500 feet; :first 830 ·pounds, 

. then dropped to 350 pounds. 

Produced t50 barrels of emulsion between 

5 p .. m. and 4 a. m. 

~ug. 1. Made 70 barrels.in 36 hours. Appears to b_e no 

·salt water. 

Aug: 2., In last 55 hours well made H)O barrels, 50 per cent 

oil, 50 per cent water. 

Aug. 3. In last 79 hours, 56 barrels oil, 53 barrels. water. 

Air at 3,410 feet. 

Aug .. 4. In laat 24 hours, 10 barrels oil, 9 barrels water.· 

Aug. 8. Salt water appears.-· 

Aug. 24. Perforat'ed, 4!-inch casing, 3,475-3,330. 

Aug. 27. Well flowed 30 barrels. 

Aug. 28 .. Well on pump .. '

[Telegrams to Bell & Henderson.)· 

1911. 

July 16. Pumped 30 barreJs;· 50 per cent water. 

17. Pumped 35-barrel!3; 90 per cent water .. 

18. Pumped 40 barrels; 50 p~r cent water .. 

19. No report. 

20. Pumped 30 barrels; 40 per cent water. 

21. Pumped 30 barrels; 10 per cent water. 

22. ·Pumped 23 barrels; 20 ·per cent water. 

23. Pumpe4 30 barrels; 10 per cent water. · 

24. Pumped 20 barrel!3; 5 per cent water. 

25. Pumped 23 barrels; 10 per cent water. 

26. Pumped 30 barrels; 5 per cent water. 

27. ·Pumped 23 barrels; 7 barrels water. 

28. Pumped 28 barrels; 4 barrels water. 

29~ Pumped 26 barrels; 4 hnrels ,-rater. 

2. Pumped 23 barrels; 4 barrels·water. 

3. Pumped 18 barrel_s; 5 barrels water. 

!. Pumped 24 barrels; 5 barrels water. ' 

5. Pumped 21 barrels; 4 barreJs water. 

6. Pumped 20 barrels; 4 barrels water. 

7. Pumped 20 barrels; 4 barrels water. 

8. Pumped 25 barrels; 4 barrels water. 

9. Pumped 20 barrels; 4 barrels water. 

10. Pumped 22 barrels; 4 barrels water. 

11. Pumped 20 barrels; 3 barrels water. 36° Baume. 

12 .. ;pumped 22 barrels; 4 barrels water. 

13. Pumped 22 barrels; 4 barrels water. 

14. Pumped 22 barrels; 4 _barrels water. 

15. Pumped 20 barrels; 4 barrels water. 

16. Pumped 20 barrels; 4 barrels water. 

.17. Pumped 20 barrels; 1 barrel water. 

18. Pumped 20 barrels; 3 barrels water. 

19. Pumped 20 barrels; 3 barrels water. 

20. Pumped 20 barrels;, 4 barrels water. 

Shut down .. 

Well No.3, sec. 24, T. 30 S., R. 23 E. 

[Telegrams.] 

1912. 

Mar. 28. Rigging up ' to perforate. 

· 29-Apr. 12. Perforated 3~700-2,500. 

Apr. 13-18. Pumping water and a little oil. 

19. ·Pumped dry to 2,000. Produced 30 barrels· oil 

in first 36 hours. 

2(}-28. Bailing, etc . 

29. Started on pump 4 p. m. Pumped 30 barrels 

oil and water. 

30. After pumping 30 hours well pumped dry to 

depth of 2,500 feet, during which time pumped. 

15 barrels oil,.45 barrels water. 

May 1. Pumped dry to 2,500 feet. 

2. Pumped head off in four hours. Made 25 barrels 

· (5 oil, 20 water). 

3. P_umped- 25 barrels, 3 oil, rest water. 

· 4. Pumped 25 barrels, 3 oil, 37 water. 

5. Pumped 25 barrels, 3 oil, 27 water. 

6. Pumped 16 barrels oil and water. 

7. Pumped 15 barrels oil an~ water. 

8. Pumped 12 barrels, practically all water. 

9. Pumped 12 barrels, principally water. 

10. Pumped 12 barrels, principally water. 

11-23. Perforated 3,100-2,500. 

· 24. Put on pump at 2,,500 .. 

25. 25 barrels oil, 100 barrels water. 

26; 27. Rods parted, etc. 

28. Pumped 25 barrels oil, 100 barrels water. 

29. Pumped 50 barrels oil. 

30. Pumped 60 barrels oil, some water. 

31. Pumped 40 barrels oil, 50 barrels water. · 

'June 1. Pumped 40 barrels oil, 20 barrels water and shale. 

2. Pumped 45 barrels oil, 25 barrels mud, 10 water. 

3. Pumped 50 barrels oil, water, and mud. 

4. Pumped9o"barrelsoil,10M.andB.S.inninehours! 

Shows great improvement. · 

5. Pumped 190barrelsoil, 10M. and B.S. in24hours. 

6. Pumped 125 barrels net, no trace of water. 
AREAS ADJACENT TO SUNSET-MIDWAY FIELD~ 169 

1912. 

June 7. Pumped 105 barr~s oil, some water. 

8. Pumped 115 barrels, practically pure oil. Gravity 21.8°, 9/10 water, 2/10 B. S. 

9. Pumped i75 barrels pure oil; shows quantity gas. 

10. Pumped 120 barrels; lots of gas. 

11. P-ttlled to. put on tight gas head. 

12. Well flowed almost continuously while pulling 

tubing to put on tight gas head between 8 

inches and 6 inches. Started flowing between 

casings. At prese:1t is ma:dng 800 or 900 barrels; may not keep up at this rate. 

13. Stopped flowing. Putting on pump. Gravity 

19.7°; 0.3 per cent water, 13 per cent B. S. 

14. Flowed 250 .barrels through 6t-inch casing. 

Reduced to 2-inch outlet. 

'15. Flowed 300 barrels through 6-inch casing. 

16. l~lowing through 6-inch casing spasmodically. 

Produced at lowest figures 750 barrels oil. 

17. Flowed 325 steadily. · 

18. Flowed steadily 225.; agitated by bailer. 

19. Flowed 200. Hole bridged at 2,940. · 

20 .. Flowed 200. 

21. l~lowed 175 

22. Flowed 150 

23. Flowed 150 Cl . b 'd 

24. Flowed 150 eanmg out n ge. 

25. Flowed 150 

26. Flowed 125 

27. Flowed 100. 

28. Flowed 100. · 

29-July 11. Washing, etc. 

July 12. Placed on pump. Flowing about 350 harrels per 

day through tubing. As yet has not made all 

oil that was put into wash hole out.· 

13. Stopped flowing. · 

14. Started flowing; made about 350 barrels. 

15. Sand at 2:500. Flowed 75 barrels. 

16. Flowed 75 barrels. 

17. Flowed 75 barrels. 

18. Flowed 75 barrels. Hole filled to 2,500. In 

same condition as before washing. 

19. Flowed 100 barrels. 

20. Flowed 75 barrels. Filled with sand. 

21. Filled with oil to clean out. 

· 22. Flowed 75 barrels. 

July: 23-Aug. 7. Cleaning out.. 

Aug .. 8. Lost string small tools. . 

11. Well flowed 100 barrels per 2.4 hours. 

12. Flowing 100 barrels oil, 3,000,000 cubic feet gas. 

13. Flowing ioo barrels oil, 3,000,000 cubic feet gas. 

14. Flowing 100 barrels oil, 3:000,000 cubic feet gas. 

15-20 .. Flowing about same as above .. All this time 

fishing for lost tools. 

21-23 .. Shutting down. 

The well of the Scottish Oilfields Co.,. which 

is in the west end of the belt described above 

as structurally the most favorable for the 

accumulation of oil, did not obtain oil,. alt~ough it was drilled 4,005 feet and should 

therefore have penetrated beds lying at the 

. same horizon-from which the oil was derived 

in the Associated Oil Co's. wells. It is worthy 

of note, however, that this well was drilled 

with rotary tools below 2,200 feet. 

The well of the Midway Valley Oil Co. in 

sec. 12, T. 31 S., R. 24 E.; was drilled deep 

enough to penetrate beds at the same horizon 

as those from which the wells of the Associated . 

Oil Co. obtained oil. This well, however, Is· 

not in the belt of most favorable structure. 

WHEELER RIDGE. 

The anticline that forms Wheeler Ridge is 

the easternmost of the folds that occur in the 

foothills along the southwest side of San 

Joaquin Valley. This fold is limited on the 

west by the fault or zone of fracture that is 

believed to be the northeast end of the fault 

along Tejon Pass. East . of Coaloil Canyon 

the Wheeler Ridge anticline plunges eastward,· 

and it probably does not affect the .Tertiary 

beds mucli beyond the east end of the ridge. 

The structure of Wheeler Ridge and the 

possible occurrence of oil in the rocks there 

have been described by Robert Anderson, 1 and 

it is necessary here to do no more than to offer 

a slight correction to his interpretation of the 

structure, and to record the results of the 

drilling done since his visit. Those interested 

in the area and desiring a more detailed description of it are referred to his report. 

Anderson interpreted the structure as a 

'' dom~like anticline that rises in th~ foothills 

and sinks abruptly ag~in at· the edge of the 

valley a few miles distant." The writer's 

interpretation of the structure is that the 

west end of the anticline does not plunge . 

normally, but that. west of Coaloil Canyon it 

is broken and finally ended by faults. This 

difference in interpretation is of some practical importance, for if the fault hypothesis 

is accepted it is more easy to understand the 

occurrencf\ of the oil seep in Coaloil Canyon. 

That seep, unlike most ·of those along the 

border of San Joaquin Valley, is not ·at the 

contact between the diatomaceous shale and 

the overlying formation, for the oil issues from 

beds that are well above the base of ·the "late 

Tertiary gravel, sand, and clay which rest 

upon that shale. The writer believes that 

the oil h~s worked its way up along fractures 

which cut through these late Tertiary beds, 

.and that, although the oil sand that crops out 

in Coaloil Canyon may underlie a consider.:. 

able area in the west end of the fold, it does 

1 U. S. Geol. Survey Bull 471, pp. 125-132, 1912. . 
Q 

170 THE SUNSET-MIDWAY OIL FIELD, CALIF.-PART I. 

not necessarily underlie the east end, where formation as mapped in this report. Along 

the fold is unbroken. San Emigdio Creek near the Devils Kitchen 

It is therefore necessary to look not to this these beds rest upon a dark clay shale which is 

sand but to, a sand that lies deeper, perhaps mapped as the top of the Tejon formation. 

very much deeper, as the possible productive This shale contains considerable carbonaceous 

oil sand ih thb part of the ridge. Unfor- matter and in a measure resembles the impure 

tunately the structure is so complicated south facies of the diatomaceous shale that occurs in 

of Wheeler ·Ridge that it is impossible to the younger Tertiary formations in this and in 

estimate the thickness of these late Tertiary other parts of California, and it seems to the 

beds which overlie the diatomaceous shale writer to be not altogether unreasonable toreand thus to give a rough measure of the depth gard this shale as a possible source of oil. 

at which oil sands might be expected to un- Should oil have been formed in this shale the . 

derlie Wheeler Ridge. · small antiClinal fold mentioned above would 

A number of wells have been drilled in this offer a structural trap in which the oil would 

area, but only one of them was so located as probably tend to collect, the beds that would 

to give the structure an adequate test. · This probably serve as reservoirs being those which 

well, which is usu.ally ·known as the G.· R. lie at the base of the Vaqueros formation.. The 

well, was in the center of sec. 26, T. 11. N., general structure of this area is shown in 

R. 20 W., in the low wind gap that cuts geologic :;;ection G-G', Plate II. 

through the ridge. ·According ·to reports in- ·It must be stated, however, that the prospect 

the press, it was drilled to a depth of 2,925 f~r obtaining oil in commercial amounts in a 

feet, at which the 4!-inch casing became well drilled along this fold does not appear to be 

stuck and the well was abandoned, commer- very bright, for in the first place there is no 

cial amounts of oil not having been found. field evidence that the shale· in the upper part of 

The writer has no information as to. the the Tejon has actually ,given rise to oil; and in · 

character of the beds through which this well the next place even if oil had been formed in 

passed, but he believes that the late. Tertiary the shale the area from which oil might drain 

rocks which form the surface here were not . out of the shale. _and collect in the Vaqueros· 

completely penetrated. The well . does not formation along the .anticline is small, for the 

prove the· absence of commercial amounts of beds are-cut by faults of considerable size both 

oil in Wheeler Ridge, but it does show that the north and. south of the fold; This area therebelt beneath which oil may·occur in consider- fore does not appear to beone in which drilling 

able amounts and not too deeply b~ied to be is now advisable, nor shoUld drilling even be 

re.ached by-the drill is narrow-much narrower considered until the value of: oil has so ineven than Anderson suggested. · '· creased that the operator can afford· to take a 

The ridge is, however, worthy of another and very much greater risk thana~ present .. 

more thorough test before it is definitely aban- . mGHER PARTS OF THE TEMBLOR 'RANGE. doned, but the test well should be located close 

to the axis of the anticline in the central part 

of the ridge, and the operators should be prepared for deep _drilling. 

FOOTHILLS OF THE SAN EMIGDIO MOUNTAINS. 

For the most part the structure of the foo~ 

hills of the San Emigdio Mountains is too 

broken by faults to favor the accumulation 

and retention of petroleum in · considerable 

amounts. In one area, however, it seems possible that oil may ,occur. This area lies along. 

the small anticline which ~xtends from a point 

on the east side of San Emigdio Creek about. 3 

miles above its mouth eas.tward to Pleito Creek. 

The beds forming the surface along the axis of 

this fold are in the lower part ·of the Vaqueros 

· The higher parts· of the Tern blor Range west 

of the Sunset-Midway district are formed 

chiefly of the diatomaceous Marioopa sh8le, 

which is much folded. As this shale is believed to be the original so.urce of the petroleum 

obtained in the main field, and as in places the 

shale now contains oil in· considerable amount 

in certain sandy lenses that are bedded with 

the finer-grained material, the higher ·parts of 

the range where the shale is not too closely 

folded and fractu1:ed must be considered as 

possible oil land. Moreover, the shaly beds 

that co_mpose the upper part of the Vaqueros . 

formation west of Santiago Creek are very 

similar to those composing t4e Maricopa shale, 

and this formation · contains oommercial 
ELEVATIONS OF WELLS IN NORTHERN PART OF MIDWAY FIELD. 171 

amounts of oil in at least one part of the areathat is, along the Pioneer anticline. , 

The general conclusions regarding the possible occurrence of oil in this part of the area 

expressed by Arnold and Johnson in the preliminary report 1 may be repeated here: 

In a region of complex structure like that of the Temblor 

Range the conditions affecting the accumulation of . oil 

differ widely within short' distances, so that a detailed 

study of each particular locality is necessary b~fore a 

proper conclusion can be drawn as to the depth of the oilbearing zone below the surface. It may be said in general, 

however, that the most favorable localities are near the 

a..'Ces of the anticlines, especially those with relatively 

low dipping flanks. Another favorable locality is along 

any lino which marks a change from a low to a steep dip, 

both dips being in the same direction. This is simply a 

special form of the anticline in which the plane of the axis is 

oblique instead of vertical, as in a symmetrical anticiine~ 

An anticline which appears to fulfill these favorable conditions at one place or another along its course is the one 

lying one-half to 1 mile northeast of the crest of the [Tem1 U. S. Gool. Survey Bull. 406, pp. 211-212, 1910. 

blor] range in the region southwest of the developed part 

of the Midway district. Other anticlines in the territory 

under discussion also appear favorable at one place or 

another, these particularly favorable localities usually 

being indicated on the map by anticlines with low dips. 

ELEVATIONS OF WELLS IN NORTHERN PART OF 

MIDWAY FIELD. 

The following· table gives the elevations 

above sea level of the oollars of several wells 

in the northern part of the Midway field-the 

part for which s~face contours are not shown 

on Plates I and III. These elevations have 

been compiled from the records of the oil 

companies. 

The elevations marked A were determined 

instrumentally; those not so marked may have 

been determined accurately, but information 

regarding the method of determining them was 

not available. ·They should therefore be regarded as subjeot to an error of perhaps 20 

feet. 

Elevations of wells in northern part of Midway oilfield. 

Company. Old name or lease name. 

Armstrong & J ergins .. :..... . . . .................. . Do .................................. · ...... . Do .................. : ........ · ............. . 

~~::::: ::::::::: :~: ::::1:::::::::::::::::::: 

Associated Oil Co ............ I ................. : .. 

Do ................ · ........................ . Do ........................................ . Do ........................................ . Do ......................................... . Do ........................................ . Do ......................................... . Do ................ ~ .................... ~ .. . Do ........................................ . ])o ............................. · ........ · ... . 

Do ................ : ...... · .................. . Do ................. · ........................ . Do ................. · ....................... . Do ........................................ . Do ....................................... :. Do .............. ; ......................... . Do ...................................... · .. . Do ................ · ........................ . Do ........................................ . 

No. of 

well. 

Qu.arter. 

1 SW ..... . 2 sw ..... . 3 sw ..... . 4 SW ..... . 5 sw ..... . 1 NE ... .' .. 1 NE ..... . 2 NE .... .. 3 NE ...... · 

4 NE ..... . 5 NE ..... . 6 NE ..... . 21 NE ..... . 24 NE ..... . 25 NE ..... . 26 NE .. .' .. . 33 NE ..... . 34 NE .... .. 35 NE ..... . 41 NE ..... . 42 NE ..... . 43 NE ..... . 51 NE .. · ... . 

52 NE ..... . 61 NE ..... . 62 NE .... .. 54 NE ..... . 72 SE ...... . 83 SE ....... . 1 SW ..... . 4 NW .... · .. 23 sw ..... . 32 SW ..... . 33 SW ..... . 43 SW .... .. 52 SW ..... . 

Location. 

ElevaSection. Township · ti9n (feet). S. Range E. 

26 

26. 

26 

26 

26 

35 

35 

35 

35 

35 

. 35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

20 

20 

20 

22 

22 

22 

22 

22 

22 

22 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

'31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

22 1, 500 A 

22 1, 500 

22' 1,500 

22 1, 499 A 

22 1, 501 A 

22 1, 365 A 

22 1, 364 A 

22 1, 374 A 

22 1, 392 A 

22 1, 414 A 

22 1, 449 A 

22 1, 438 A 

22 1, 381 A 

22 1, 390 ± 

22 1,432 

22 1, 456 A 

22 1, 409 

22 1,424 

22 1, 439 

22 1, 429 

22 1, 424 

22 1, 436 

22 1, 444 A 

22 1, 443 

22 1, 457 A 

22 1, 455 A 

23 1, 027 A 

23 1,135 

23 1,163 

23 1, 207 

23 998 

23 1,150 

23 1, 133 

23 1, 102. 

23 1,102 

23 1,141 
172 THE. SUNSET-MIDWA;Y OIL FIELD, CALIF.-PART I. 

Elevations of: wells in northern part of Midway oil field-Continued. 

Location. 

Eleva- Company. Old name or lease 

,name. · No. of 

well. 

Quarter. Section. Township· tion.(feet). Range E. s. 

Associated Oil Co ........... _ ... _ ...... _ ........ . 63 SE .... ~ .. . 

Do ...................... -··········-·······-- 3 sw ..... . Do .................... · .................... . 24 NW ..... . Do .............. ~ ......................... . 33 sw ..... . Do ......................................... . 42 sw ..... . Do ....... : ................................ . 53 SE ....... . Do ........ · ..... : .......................... . 72 SE ....... . Do ......................................... . · '91 SE ....... . Do.: ...................................... . 93 SE ....... . Do ........................................ . 44 NW ..•... Do: ........................................ . 74 NE ..... . Do ......... -~ .............................. . 96 NE ..... . Calidon·Petroleum Syndicate ...... _ ............. . California Star Oil Co ............................ . 1 sw ..... . 1 sw ..... . Do ..................... ·········'·········· .2 sw ..... . Do .......................... ~ ............... . 3 sw ..... . . Do.; ......... : .............. __ ............ . 4 sw ..... . Do ........................................ . 5 sw ..... . Chanslor--Canfield. Midway Oil Co. . ...... _ ..... _ . _ ... . 1 NW ..... . 

Do ..................... ---------·---------- 1 SE ....... . Do ......................................... . 2 ·SE. ...... . 

Do ........................................ . 3 SE. ...... . 

Do ........................................ . 4 NW ..... . Do ........................................ . 5 ·sE ....... . 

Do ............. · ............................ . 7 NW~ .... . Do ........................................ . 8 NW ..... . Do ............ ~ ........................... . 9 SE .......• Do ........................................ . 10 SE ....... . Do ......... : ......... _ ................•.... 11 NW ..... . Do ........... : ............................ . 12 NW ...... . Do ........................................ . 13 SE ....... . Consolidated MutuaJ Oil Co.. Mays ............... . Do ..... ~ .................... do ............. . 1 sw ..... . 2 NE.: .... . Do ...... · .................... do ............ . 3 NW ..... . Do ................... _ ..... ~do ........ ·._ .... , 4 NE ..... . Do.~ .... · ..... · ............ " .. do ............ . 5 NE ..... . Do ......................... ~do ............. . 6 NE ..... . Do ... _ ............ _ ........ .'do .......... _ .. 7 NE.: .... . Do .......................... do ............ . 8 NE; .... . Do .......................... do ............ . 9 NE ..... . Do ........................... do ............ : 10 NE ...... : 

~~::::::::::::::::::::: :::::~~:::::·:::·::::: 11 NE ..... . 12 NE ..... . Do .......................... do ........... ~.~ 13 NE ..... . Dabney Oil Co ................................. . Do .................................... · .... . 1 SW ..... . 2 .SW ..... . 

Do ....................................... ~ ~ 3 SW ..... . Do ......................................... . .4 SW ..... . 

Do ........ · ................................. . 5 sw ..... . Doheny Pacific Petroleum Fairfield .......... . Co. 

1 sw ..... . 

El Camino Oil & Develop- ................... . ment Co. 

1 SW~---·· 

Do ........................................ . 2 sw ..... . General Petroleum Co.·. . . . . Carnegie ....... ~ .. . Kern Trading & Oil Co ......................... . Do ........................................ . 

1w. NE ..... . 21 SE ..... . 2 NW ..... . Do ........................................ . 6 sw ..... . McKittrick Oil Land Co ..... Starlight ........... . Maxwell Oil Co ................................ . 1 Nw ...... . 1 NE ..... . Midland Oil Fields Co. (Ltd.) ................... . Do ........................................ . 1 sw ..... . 2 NW ..... . Do .......................................... . 3 NE ..... . Midway Royal Petroleum Co .................... . Miley & Buley .... ~.~ . . . . . . . Kimball & Cr~llin .. Record Oil Co. • • . . . . . . . . . . . . .................. . 

1 NW ..... . 1 NE ..... . 1 NE .... .. Do ... ; ...••••............ · ................... . 2 NE .•.... 

22 

26 

26 

26 

26 

26 

26 

26 

26 

. 34 

34 

34 

19 

26 

26 

26 

26 

26 

27 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

35 

28 

28 

28 

. 28 

28 

28 

28 

28 

28 

28 

28 

•28 

28 

26. 

26 

26 

26 

26 

19 

26 

26 

'9 

21 

27 

27 

21 

27 

12 

12 

12 

19 

21 

28 

28 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

.31 

31 

31 

31 

31 

31 

31 

·31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

. 31 

31 

. 31 

31 

31 

. 31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

'31 

31 

31 

31 

31 

31 

31 

~1 

31 

31 

31 

31 

31 

31 

31 

23 

23 

23 

23 

23 

23 

23 

:.:!3 

23 

23 

23 

23 

23 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22" 

22 

22 

22 

22 

22 

22 

22 

'23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

22 

22 

22 

22 

22 

23 

22 

22 

22 

23 

23 

23 

.22 

22 

22 

22 

22 

23 

22 

23 

23 

·1, 210 

992 

1, 105 

1,049 

1,140 

1,031 

952 

948 

1,150 

935 

939 

1,020 

1, 106 

1, 486 A 

1, 481 A 

1, 465 A 

1,.457 

1,455 

1, 555A 

1, 522 A 

1, 454A 

1,473 A 

1, 458 A · 1"514A 

1:468 A 

1,484A 

1, 490 A 

1, 471 A 

1, 488 A 

1, 473 A 

1, 498 A 

1, 162 

1, 192. 

1, 183 

1, 138 

1,215 

1,204 

1, 133 

1,167 

1,236 

1,173 

1, 198 

1,215 

1,194 

1, 495 A 

1, 478 A 

1,480 A 

1,484A 

1,491 A 

1,152 

1,420A 

1,447 A 

1,530 

1, 200 A 

1, 225 A 

1, 158 

1,734 

1,540 

1, 266 A 

1, 201 A 

1,178 A 

1,157 

1,634A 

1,195 

1,206 .. 
ELEVATIONS OF WELLS IN NORTHERN PART OF MIDWAY FIELD. 173 

Elevations of wells in northern part of Midway oil field-Continu~d. 

Location. 

No.of .1------~-------.-------.-------1 Eleva-· Company. Old name or lease name. well. 

Quarter. . tion (feet). Township ·Range E. 

Record Oil Co ................................. . ])o ........................................ . 

Soudan Oil Co ................................. . Do .................................. -~ .... . Do ........................................ . Do ........................................ . 

Do ................................ , ........ . Do ........................................ . Do ............................. : .......... . Do ........................................ . Do ........................................ . Standard Oil Co ................................. . Do ........................................ . Do ........................................ . Do ........................................ . Do ..................... Burr ............... . 

Do ........................................ . no ..................... ···················· Do ........................... : ............ . Do .......................... ~ .. : ......... · .. Do ........................................ . Do ................ : ........ · ............... . Do ........................................ . Do ........................................ . Do ........................................ . Do ........................................ . Do ........................................ . Do ...................................... · .. . Do ................................... ~- ... . Do ........................................ . Do ........................................ . Do ........................................ . Do ........................................ . Do ........................................ . Do ........................................ . Do .......... : ............................. . State Consolidated Oil Co ... : .... : .............. . Do ........................................ . Do ........................................ . Do ............................ · ............ . Do ........................................ . Do ........................................ . Do ........................................ . Do ........................................ . Do ............................ ~ ........... . Do ........................................ . Do ........................................ . Do ............ : ........................... . Do ........................................ . Do ...... · .................................. . Do ........................................ . Toronto Midway Oil Co ........................ .. Do. . . . . . . . . . . . . . . . . . . . . Sheridan ........... . 

United Oil Co .................... ~ ............ .. Do ........................................ . Do ........................................ . Do ........................................ . \Vilkes ....................................... · · · Do ......................................... . 

3 NE ...... 4 NE ...••• 

1 sw ..... . 2 SW ..... . 3 sw ..... . 4 SW ...... . 5 sw ..... . 6 sw ..... . 7 sw ..... . 8 sw ..... . 9 sw ..... . 1 SE .•.•.. 

2 SE .•.••• 3 SE .•.••• 4 SE .•...• 1 sw ..... . 1 sw ..... . 2 NW .... .. 3 NE ...•.. 4 SE .•.•.. 5 sw ..... . 6 SE .•.•.. 7 sw ..... . 10 sw ..... . 1 sw ..... ~ 

2 NW .... .. 3 NE ...•.. 4 SE .•.•.. 

5 sw ..... . 6 sw .... .. 7 SE .... .. 

8 sw ..... . 9 NW ..... . 1 NW .... .. 2 NW .... .. 4 NW .... .. 1 sw ..... . 2 .SW ...... ··· '3 sw .... .. 4 sw ...... . 5 sw ..... . 6 sw ..... . 7 sw ..... . 8 sw .... .. 9 sw .... .. 10 sw ... ~ .. 11 sw ..... . 12 sw ..... . 13 sw ..... . 14 sw ..... . 15 sw.~ .... . 1 sw ..... . 1 NE ..... . 22 SE .••••. 23 NE ...••. 25 SE .•.•.. 26 sw ..... . 1 SE .••••. 2 SE ••.••. 

Section. 

28 

28 

26 

26 

26 

26 

26 

26 

26 

.26 

26 

16 

16 

16 

16 

17 

22 

22 

22 

22 

22 

22 

22 

22 

26 

26 

26· 

26 

26 

26 

26 

26 

26 

28 

28 

28 

26 

26 

26 

26 

26 

26 

26 

26 

26 

26 

26 

26 

26 

26 

26 

18 

10 

20 

20 

20 

28 

28 

28 

s. 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

. 31 

31 

'31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

·31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

31 

.31 

31 

31 

31 

31 

31 

31 

31 

31 

23 

23 

22 

22 

22 

22 

22 

22 

22 

22 

22 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

23 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

22 

23 

22 

23 

23 

23 

'23 

23 

23 

1,232 

1,261 

1,486 

1,480 

1, 487 A 

1, 466 A 

1,475 

1,460 

1,065 

l, 453 

905 A 

907 A 

956 A 

1,071 A 

1,150 

1,106 

1,064 

.1,076 A 

1,127 A 

1,131 A 

1, 055 A 

1, 096 A 

1, 073 

1,153 A 

1,179 A 

1,100 A 

1,133 A 

1,118 A 

1,144 A 

1, 066 A 

1,088 

1,174 

1,193 

1,193 

1,175 

1, 449 A 

1, 491 A 

1, 465 A 

1, 455 A 

1, 472 A 

1, 482 A 

. 1,446 A 

1, 486 A 

1, 469 A 

1,456 A 

1,458 A 

1,419A 

1, 456 A 

1, 460 A 

1, 456 A 

1,151 

1,416 

1,055 

1,091 

1,155 

1,096 

1,096 

1,156 

INDEX. 

A. Page. 

Accumulation of oil, influence of chemical and physical properties 

on ..••................................................ 82-83 

influence of grain of bods on ..•............................... 78-S2 

Aclmowlodgmonts for aid....... . .. . . . . .. . . . ... . . . . . . . . . . . . . . . . . . 19 

Adeline Consolidated Co., location of wells of.................... 145 

Alnska Pioneer Co., location of wells of.......................... 110 

Alberta Midway Co., location of wells of.......................... 94 

Alluvium, nature or............................................... 52 

American Oilfiolds area, geology and development or.. ........ 102-106 

American Oilfields Co., flowing well of........................... 66 

location of wells or •..................................... 106, 133, 136 

Anderson, Robert, cited.......................................... 169 

. and Pack, R. W., cited .........•........................... ,. 72 

Anticlines, function of, in tho formation of oil pools .... ; .......... 72-75 

secondary, concentration of oil not affected by ........ ~ ....... 77-78 

Antimony, occurrence of......................................... ·22 

Arons, productive, geology and development of .................. 88-171 

Armstrong & Jergins, elevation and location of wells of........... 171 

Arnold, Ralph, and Johnson, H. R., cited .................... ·35-36, 171 

Asphalt, Dlining of ............................................... 63-64 

Asphalt refinery, old Jowett & Blodgett, plate showing........... 51 

Associated Co., elevation of wells of ...•............. .' .......... 171-172 

location of wells of ..•........ 89,101,102,106,110,151, 154,163,171-172 

logs and history of wells of •................................ 164-169 

Associated Pipe Line Co., oil line of.............................. 67 

August Co., location of wells of ................................... · 136 

August Water Co., water supplied by............................ 68 

B. 

B. H. C. Co., location of wells of.. ............... .'................ 128 

Babcock Co., location of wells of.................................. 123 

Baltimore Co., location of wells of................................ 133 

Banklino Co., location of wells of ........................ ~ ....... 94, 129 

Barno don area, geology and development or •................. :. 150-151 

Bamodon Co., location of wells of .. .' ........................... 150, 163 

Belgian anticline, productive sands in~........................... 90 

trend of and d.f.splacement along. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 

Bibliogro.phy ..................................................... 19-20 

Boston Pacific Co., location of wells or ......... .'.................. 158 

Bmd Co., location of wells of. .................................. 117,123 

Bronner, J. C., cited.............................................. 36 

Brea ncar Muddy Crook, plato showing........................... 46 

See also Tar. 

Bronco Co., location of wells or................................... 161 

llrookshiro Co., location of wells of .............................. 98,151 

llrookshiro-Oem area, geology and development or .............. 98-100 

l3uona Fe Co., location or wells or................................ 123 

l3uena Vista Hills, "dry" gas in................................. 10 

oil and gas wells in........................................... 66 

plunging fold in, plate showing............................... 139 

position or.................................................... 17 

south half of, geology and development of .................. 158-161 

structure or. ......... " .................................... 57, 58, S9 

Buena Vista Lake, water supply from.. . . . . . . . . . . . . . . . . . . . . . . . . . . 68 

water wells at north end of................................... 67 

Buick Co., locntion of wells or.................................... 110 

Burk Co., location or wells or..................................... 123 

c. 

Calanova Co., location of wells of .................. .'.............. 150 

Cnlldon Petroleum Syndicate, elevation and location of wells or. 151, 172 

Calidon-Rocorcl area, geology and development of. .............. 151-154 

Californin, cmitral, structural features of.......................... 55 

relief map of................................................. 53 

California Counties Co., location of wells of ..................... 110,117 

California Counties-Continental area, geology and development 

or .......................... : ....................... 117-120 

Page. 

Califonila Fortune anticline, position of .......................... 57,60 

California Star Co., elevation of wells of.......................... 172 

location of wells of. ........................................ 102, 172 

California Amalgamated Co., location of wei lfof ............. 129,140,151 

. Canadian Crude Co., location of wells of.......................... 136 

Canadian Pacifi:c Co., location of wells of. ....................... .' 110 

Carbo Co., location of wells of. ............................. .'..... 129 

Caribou Co., location of wells of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 

Carmen, F. J., location of wells of. .. ·............................. 163 

Carnegie area, geology and development of ....................... 88-91 

Carnegie water well, oil brought up by ................ ·. . . . . . . . . . . 89-90 

Case Co., location of wells of...................................... 145 

Casing corroded by water, plates showing........................ 160 

Chanslor-Canfiold Midway Co., elevation of wells of.~............ 172 

location of wells of. .• 97, 98,101,102,106,110,114,117,120,123,133,172 

water supplied by............................................ 67 

Chemical nature of oil, influence of, on accumulation ............. 82-83 

Cheney Stimson Co., location of wells of.......................... 123 

Cienaga Canyon, fault in ........................................ 61, 147 

Cienaga syncline, description of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 

Climate of tho field ............................................... 17-18 

Coalinga Monterey area, geology and development of ............. 91-93 

Coalinga Monterey Co., location of wells of ....................... 91,98 

Coast Range, structure of .................... ·.................... 55 

Columbus Midway Co., location of wells of....................... 110 

Combination Midway Co., location of wells of .................. 123,163 

Combined Co., location of wells of................................ 94 

Comstock Crude Co., location of wells of.......................... 161 

Conservation of petroleum, laws opposed to ................ ~ ..... 68-Q9 

measures adopted for ......................................... 13-14 

Consolidated Midway Chief Co., location of wells of............... 145 

Consolidated Mutual Co., elevation of wells of.· ........... :....... t'12 

location of wells of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110, 151 172 · 

Continental area, geology and development of. ........ : ........ 117:120 

Corrigan Co., location of wells of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 

Cresceus Co., location of wells of..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 

•D. 

Dabney Co., elevation and location of wells of.................... 172 

Derrick, crude, over a well drilled in the nirieties, plate showing.. 64 

. and gas trap, plate showing. • . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 

Development of the field, future, suggestions for. See names of 

productit,e areas. 

history of. . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G3-G6 

.Devils Kitche:il, Ean Emigdio Canyon, plate showing............. 25. 

sections or Vaqueros formation in and near................... 30 

DeVils Kitchen syncline, anticline separating from Plei to syncline. 62 

description of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 01-62 

Diablo Range, structure of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 

Doheny Pacific-Carnegie area, geology and development of. . . . . . . 88-91 

Doheny Pacific Petroleum Co., elevation of wells or.............. 172 

location of wells of ....................................... 89,91,172 

Dominion Co., location of wells of................................ 94 

Drilling, methods of............... . .. . .. . .. . . .. . .. .. .. .. .. .. .. .. . 10 

Dunlop Co., location of wells of.......... . . . . . . . . . . . . . . . . . . . . . . . . . 129 

Dunlop-Section Twenty-five area, geology and development of .. i28-133 

Durango Co., location or wells of .............. ·................... 97 

E. 

Eagle Creek Co., location of wells of ........................ 102, 110, 1H 

East Midway Co., location of wells of.. ................. :......... 163 

Edmtmds Midway Co., location of wells of ..................... 133, 135 

El Camino Co., elevation of wells of.............................. 172 

location of wells of. ......................... 9S, 101,102,161,162,172 

F.l Camino-Pioneer Midway area, geology and development of. .. 100-102 

El Cerrito Co., location of wells of. ............... .'............... 146 

F. I Dora Co., location of wells of.................................. 140 

175 
176 INDEX. 

Page. 

Elevations or' wells in northern part of Midway field ............ 171-'-1i3 

Elk Hills, geology and development of .......... ; . . . . . . . . . . . . . . 11}2-169 · 

position of. ..... ~ .......................................... ·: 17 

section of Paso Robles formation in.......................... 49 

structure of. ............................................ · .. 57, 58-59 

Elk Hills Midway Co., location of wells of........................ 163 

Elk Hills Oil Co., location of wells of............................. 163 

Elliott Co., location of wells of. .................................. : 94 

Elkhorn Co.,.location of wells of.................................. 129 

Empire Fuel & Gas Co., location of wells of...................... . 117 

Engineers-Coalinga Monterey area, geology and development of .. 91-93 

Engineers Co., location of wells of .................... ~............ 91 

Etchegoin.formation, bed filled with fossils at base of, plate showing................................................... 46 

·distribution and lithology of ................................. 44-47 

oil sands in .................................. 91, 93,94-95,96, 9S, 101,. 

103,107,111-112,115,117,120-121, 

130, 134, 136, 140, 152, 155, 159, 162 

stratigraphic relations of..................................... 44 

F.thcl D. Co., location of wells of. ... ; .. ~ .......................... · · 132 

F. 

Fairbanks Co., location of wells of................................ 123 

Fairfield Co., location of wells of. ..... ·............................. 151 

Faults, distribution and trend of. .......................... 60-61,62-63 

effects or, on tho accumulation of oil .... : ................... 129-130 

structure dominated by .............. · ........... :; ........... 60-Gl 

Field work, record oL ...................... · ..................... 18-19 

Fold, plunging, in Buena Vista Hills, plate showing.............. 139 

Folds, function or, in the formation of oil pools ................... 72-75 

Foothills east of San E migdio Creek, plate showing...... . . . . . . . . . 32 

on north slope of San :E:migdio Mountains, plate showing..... 32 

on west side of S~It Creek, plate showing. . . • . . . . . . • . . . . . . . . . . 18 

Fossils, bed filled with, at base of E tchegoin formation, plate showing...................................................... 46 

occurrence of .......................... 24, 25,30, 32, 35,38, 41, 43,45, 53 

G. 

G. R. well, history of. ...................... .-...................... 170 

Gas, dry and wet, position of, with regard to oil.................. 83 

formation of .................. , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 

utilization of .................................... :............ 66 

wens yielding ................... ;............................ 160 

Gas trap and derrick, plate showing ................... ~....... . . . 64 

Gasoline, proportion of, in'the oil.................................. 10 

"squeezing" of, from thegas................................. 10 

General Petroleum Co., elevation of' wells of. ...... h • • • • • • • • • • • • • 172 

location of wells of ..................................... 89,91,94,98, 

110,117,123,129,133,136,140,145,151,158,163,172 

General Pipe Line Co., oil line of................................. 67 

Geologic features, large, determining the location of the oil field 71-75 

lesser, controlling position of oil within the field .............. 75-83 

Geologic map of the Sunset-Midway oil field ................. In pocket~ 

Geologic sections, plates showing .... '.••..••••..•............. In pocket. 

Geologist, petroleum, work of ....... , ............... ,............. 14 

(}eology of the field, summary of ....•.......................... , • 9 

Globe anticline, description of.. .................................. 91,94 · 

Globe-Bear Creek area, geology and developrp.ent of .............. 93-96 

Golden Gate Co., location of wells of ....... :. . . . • . . . . . . . . . . . . . . . . . 161 

Golden West Co., location of wells of............................. 145 

Good Roads Co., locatio:t of wells of.............................. 145 

Grains, fineness of, in relation to oil content ................ ,..... 128 

influence of size, shape, and arrangement of, on porosity...... 79 

Granite boulder in San Joaquin Valley, plate showing............ 19 

west of Follows, plate showing............................... 19 

Granitic rocks, nature and distribution of........................ . 22 

Gravels, Tertiary, and rioistocene or Recent, unconformity between, plate showing ...•. :........................... 52 

Gra\ity of oil ...................•....••...... :. . . . . • • . • . • . . . . . 10, 86-87 

Great Valley of California, boundaries of.......................... 55 

Green & HutchinSon, location of wells of......................... 163 

Griffith Co., 1 ocatiol). of wells of.. •• ~.............................. 123 

II Gusher sands," explanations of................................. 86 

Gypsite, occurrence of.. ••........................... : . ~ .. : . . . • . . . 34 

H. 

Hale McLeod Co., location of wells of .••••..••..•. : ............. 114,120 

Hanford Sanger Co., location of wells of.......................... 145 

Page. 

Hart Co.,location of wells of.......................... 163 

Hawaiian area, geology and development-of .................... 106-pO 

Hazelton Crude Co., location of wells of........................... 145 

Hillcrest Co., location of wells of................................. 163 

History of development of tho field ............................... 63-66 

Hondo Co., location of wells of.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 

Honolulu anticline, productive area on ..................... 158-lll9, 161 

Honolulu Consolidated Co., location of wells of ..... 106,110,158,159,160 

sands yielding gas of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 

· water supply of.............................................. 68 

I. 

Ida May Co., location of wells or................................. 145 

Igneous rocks, Tertiary,'distribution of .......................... 52-53 

lithology of .... ·.............................................. 54 

stratigraphic relations of ..................................... 53-54 

Indian & Colonial Co.; location of welJs of........................ 123 

J. 

J. M. S. Co., location of wells of. ........... :..................... 129 

J. M.S. sand, nature of.......................................... 131 

production from. . . . . • • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 

Jade Co., location of wells of..................................... 123 

Jamison Co., iocation of wells of.................................. 123 

Jewett & Blodgett, early operations by .......................... 63-65 

location of wells of........................................... 146 

Jewett & Blodgett asphalt refinery, plate showing............... 51 

Johnson, H. R., Arnold, Ralph, and, cited ................... 35-36,171 

Johnson Co., location of wells of .................. : ..... ·.......... 145 

K. 

K. & C. Co., location of wells or.................................. 97 

Kalispell Co., location of wells of................................. 114 

Kanawha Co., location of weBs of................................ 117 

Kern Midway Co., location of wells of. ............. ·.............. 163 

Kern Trading & Oil Co., acknowledgment to .•............ ·....... 19 

elevation of wells of. • • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 

location of wells of .. ~....................................... 91, 94, 

98,101, ito, 114, 117; 133,136,140,145,151,154, 158, 160,112 

Knickerbocker Co., location of wells of........................... 133 

Knob Hill Co., location of wells or................................. 123 

L. 

La Blanc Co., location of wells of................................. 145. 

Lakeview Annex, location of wells of ..................... · ......... · 161 

LakeView area, geology and development of ............ .' ....... 136-139 

Lakeview No.1 gusher, flow of. ............. : .................... 65-66 

plate showing. . . . . . . . . . .. . .. . .. .. .. • . . . . . . . . . . .. . .. . . . . .. . . . • 138 

Lakeview No. 2 gusher, plate showing.. .. . . .. . .. .. .. .. • .. .. .. .. . ; 138 

flow of. ............................. · ........................ ; 66 

Lakeview No.2 Co., location of wells of ................. 133,136,140,161 

well No. 1 of, plate showing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 

Lands, oil, withdrawals of ..........•............................ · 68-70 

Laws and customs injurious to the oil and gas industry ••••...... 68-69 

Lenticularity of beds, disadvantage .of............................ 79' 

Lithology. See Rocks, nature of. 

Location of the field.' . .'.......................................... 9, 15 

large geologic features determining ........................... 71-75 

Lockwood-Stratton water area, geology and development of .... 120-123 

Lockwood-Talara area, geology and development of ••.......... 123-128 

Los Angeles, gas pipe line to ...•.... · ......... : . . . . . . • . . . . . . . . . . . . 66 

Los Lobos creek, Tejon formation on, plate. showing............. 24 

Lowell Co., location-of wells of. ...... , .................. :........ 145 

Luxor Co., location of wells of. ............. ·...................... 158 

M. 

M. & M. Co., location of wells of.................................. 94 

M. G. & P. Co., location of-i,·ells of............................... 94 

McCutcheon Co., location of wells of.............................. 145 

McKittrick, section of Paso Robles formation near ............... 49-50 

McKittrick group, nature and deposition of ••.............. 21-22, 43-44 

oil sands in ........................ 114,125,130,145,147,149-150,151 

-relations of, to petroleum...................................... 44 

McKittrick Oil Land Co., elevation and location of wells of....... 172 

McNee-McLeod area, geology and development of. ....••.•••••.. 154-158 

Malayan Crude Co., location of wells of ......... · .....•....• .'...... 129 

Mammoth Co., location of wells of. .................. 89,102,106,110,114 

Manhattan Midway Co., location of wells or..................... 136 
\ 

INDEX. 

Page. 1 

Munitnh:t Crude Co., location of wells of.......................... 1~~:3 

1\fnp of California, showing relief. ......... ··'.................... 53 

of Maricopa Flat., showing structiu'c of oil and wntcr sands. In pocket. 

of old Sunset oil field, showing posit:ion of oil snnds ..... ~.... i46 

of Sunset-Midway oil fleld, showing geologic formnt.ions ... In pocket:. 

showi.ng geologic stmciurc nnd oil zones ............. In pocket. 

showing petroleum witlulra\\'als and naval pctrolcu~ 

reserves .............. · ..... , . . . . . . . . . . . . . . . . . . . . . . . . . . 68 

showing topography ................................ In pocket 

March Co., location of wells of. ... .' ... ,....................... 129 

M'n.rlcopa, water supply of ...................................... :. 68 

1\farlcopa Consolidated Co., Iocati(m or wells of................... 1<10 

Maricopa Fhlt:, flowing wells in................................ 61i 

geology nnd development or ........................ 140-145,161-162 

in 1014, pinto showing ..... ,.................................. . 61 

mup showing stmcturo of oil and water sands in ........ Iu pocket. 

Maricopa Investment Co., location of wells of................... 158 · 

Mnrlcopn,Natioual Co., )ocat.ion of wells or. ..................... '.. 1:36 

Mn.ricopa Northcm Co., location of wells of....................... HO 

.1\l'aricopn. Oil News, cited........................................ · 65 

'Mnrlcopn.-Piouccr area, geology and development of ............ 145-140 

Mnrleopa :Producers Co., Iocnt;ion of wells of..................... 161 

Maricopa shnlc, deposition of. .................................... 3~37 

distribution of..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 

gc.neml nature or ...... ; ................................... 21,35-31i 

in the Pleito Hills, plru.c showing............................. 33 

lithoiOb'Y of .................................................... 3>41 

oil snnds ln ................................... 94, 95, 97,101,103,105, 

, 107, 1H, 115-116,117,121, 1:!2, 125,130-131,137,139,145-146, HiS, 162 

origin of petroleum in ......................................... 70-71 

relations of, to petroleum ..................................... 41-42 

section of. .................. .' ........................ · ......... · 3S 

stratigraphic relations of. ........................... · .......... 35-3G 

usc of term .................... ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27-28 

n.nd clay shale of Etchcgoin formation, unconformity bct,~·ecn, 

plato showing........................................ 33 

1\f:tlricopa Star' Co., location of wells or............................ 140 

Marion Co., location of wells of. ................................ Hi', 12B 

~fascot. Co., location of wells of. . . .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. . i29 

1\fnxwoll Co., clovnt:ion and location of wells of................... 172 

Mays Consolidated Co., location of wells of....................... 150 

·Melita Co., location of wells of..................................... 145 

Mercedes Co., location of wells of................................. 163 

Mesozoic roclcs, Jato, nature and distribution of. .......... ·.· ...... 22-23 

Midland Oil Fields Co., elevation of wells of...................... 1i2 

location of wells of ........................... : ... 89, 98, 120, 140, 151 

wells 1, 2, and 3 of, sands yielding oil to....................... 90 

Midway anticline, description of................................. 103 

l)Osition of ..........................•..................... · 57, 59-60 

l)roductlve areas on .......... : ................. 101,1.06-107,114,120 

Mid wily Oil Co., Jocntion of wells of. ....... : ................... 136.145 

Midway Consolidated. area, geology and development of. ....... 110-114 

Midway Consolidated Co.,location of wells of ............ ,....... 110 

·1\fidwl\y Fields Co., location of wells of............................ 140 

~1'idwl\y Five Co., location of wells of............................. 114 

M'ldwl\y Gas Co., pipe line of ............................... ~ ... :.. . 67 

)fidway Northern Co., location of wells of ................... ;.... 140 

Midway oil field in 1907, plato showing........................... 16 

Midway Pn.ciflc Co., location of wells of.......................... 163 

Midway Poor loss Co., location of wells of .................. :. . . . . . 94 

1\fldwl\y Premier Co., location of wells of. .................... :... 114 

'Midway Uoyl\1 Co., elevation of wells of.. .................. ·....... i72 

location of wells of ......................................... i5i,'i72 

1\fidwny Vn.lloy Co., loclltion of wells of ......................... ·.:. 163 

Midway Valley sy.ncllno, productive area along ................ 110-111 

1\tidway View Co., location of wells or............................ 145 

1\flgmtion of petroleum, influence afTocting ....................... 72-75 

1\filllo l~rancis Co., location of wells of............................ 129 

1\filey & Buley, elevation and location of wells of................. 172 

l\Uocono Co., location of wells of .. ,............................... 140 

1\{ocl\1 Co., location of wells of.................................... 102 

Moct\1-Hawi\Ha.n area, geology and development of ............. 1o&-110 

Monsoon Co., location of wells of................................. 163 

Monterey group, ~so oftorm ................... : ............. · .... 21,27 

1\forgnn, Wallace, cited .............................. ~ .........•.. 63-64 

Mumcr Co., location of wells of.. ............... .'................. ·145 

Muscatine Co., location of wells of. ............. :................. 145 

109288°-~.~--1!:! 

N. Page. 

National P~cific Co., loc~tion of wells of ........................ 117, 140' · 

Navy, withdrawal of oil hmds for ................................ 69-70 

Nevada Pacific Oil Co., location of wells of.~..................... 146 

New Center Co., location of wells of.............................. 145 

North American Consolidated Co., location of wells of. ......... 117,120, 

• . . 123, 129, 154 

North Midway field, flowing wells in ............................. · 66 

North Midway syncline, tilting of beds ::llong ...... , .... ,......... 89 

Northern Exploration Co., lo::ation of wells of.................... 158· 

Northam Oil Co., lo~ation ofwoUs of............................. 145 

water supplied by. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 

0. 

Oakland Midway Co.; location of wells of......................... 91' 

Obispo Co., location of wells of................................... 140 

Occurrence of petroleum, geologic ................. , .............. 10-11 

Oil. Sec Petroleum. · 

Oil sands. Sec Sands, oil. 

Old Sunset, sulphur deposit at................................... 88 

Oleum Co., location of wells of. ............. ~.................... 123 . 

Olig Crude Co., location of well~ of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 

Oligocene and Miocene rocks, divisions of ........................ 26-51 

Onisbo Co., location of,volls of................................... 91 

Opal Co., location ofwcl:s of..................................... 128 

Origin ofpotro!cum b California ................................. i0-11 

Overproduction,stimulus to and rctardme~t of .................. 67-70 

P. 

Pacific Crude Co., location of wells of............................. 110 

property of~ geologic section along cast line of, plato showing ............................................... In pocket. 

Pacific Midway Co., location of wells of. ......................... 91,140 

Pacific Petroleum Co., location of wells of. . . . . . . . . . . . . . . . . . . . . . . . 140 

Pack, R. W., Anderson,- Robert, and, cited...................... 72 

Palmer Union Co., location of wells of............................ 123 

Paraffin Co.,·location of wells of. ............... ~................. 129 

Paso·Uobles formation, lithology of...' ............................ 48-51 · 

oilsandsin ........................................... 91, 94,114,121 

sections of. ...................................... · .......... .' .. 49, liO 

stratigraphic relations of ..................... , ................ 47-48 

thickness of ....... :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 

Petroleum, anal);ses of, needed ............. , .... ,................. SO. 

asphaltic nature of........................................... 86 

gravity of, causes of difi'erencesin ............... :............ 87 

range in .............................................. _.. . . S::i-87 

'nature of. See names of productive areas. 

vert{ cal movement of............ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 

Petroleum Center Co., location of '''ells of......................... 145 

Petrol.eum Midway Co. (Ltd.), location of wells of................ 158: 

Petroleum Syndicate, location of wells of. ........................ · 133: 

Petrolia Co., location of wells of.................................. 145; 

Phoenix synclipe, productive area on .......... .' ..............•• ;. 145· 

Pierpont Co., location of wells of. . . .. . . .. .. .. .. .. .. .. .. .. . .. .. .. . 1::9' 

Pinal Dome Co., location of wells of ............................... 94,98 

Pioneer, early drilling at ........... :. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 

section of Maricopa ,shale south of. . . . . . . . . . . . . . . . . . . . . . . . . . • . 38 

Pioneer anticline, description of.................................. 61 

· . Vaquerosformationon....................................... 34 

Pioneer anticline area, geology and development of ... : ......... l46-150 

Pioneer-Maricopa. area, geolog); and development of ............ 145-146 

l'iorieer Midway area, geology and development of ............. 100-102 

Pioneer Midway Co. See Associated Co. 

Pioneer Midway-Midway Consolidated area, geology l\lld development of .......................................... 110-114· 

Pipelines, gas, descriptions of .................................... 10,67 

. oil, descriptions of ............. : .............................. 10,67 

Placer.-mining law, unsuitable for oil and gas lands............... 68 

Pleito Creek, section of Vaqueros formation on rid.ge near... . . . . . . :32 

Plcito syncline, anticline separating, from Devils Kitchen syncline................................................. 62 

Porosity, influence of, on the aCCtli11Ulation o: oil ....... · .......... 78-82 · 

~otter Co.; Jocation .of weils of.. . . . . . . . .. . . .. .. . . . . . . . . . . . . . . . . .. . 94 

Potter, Reed & Taybr, location ofwells of ...... ·................. 163 

Pozos Co., bcation of wells of ....•............. :.................. 129· 

Prc-'rertiary rocks, nature and occurrence of .................. 20, 22-?.:r 
178 INDEX. 

Page. 

J>rcssurc in gusher wells, explanations of.· ........• :. . . . . . . . . . . . . . 86 

in oil sands, ~ause of .............................•.•......... 83-85 

relation of, to structure ......................•. :.......... 85 

Pricesofoillands ... ;............................................ 65 

Princeton Co., location of wells of ............................... : 129 

· Producers Guaranteed Co., location of wells of.. ................ :. · 123 

Producers Transport~tion Co., oil pipe line of. ........ ·............ 67 

Production of petroleum, record of... . • . . . . • . . . • . . . . . . . . . . . . . 10,66-67 

curves showing .............................. ; .... ~ ... ; . . . . . . . 66 

See also names of productive areas. 

Purpose of the report ..............................•.....•..• ; .. 13-15 

Pyramid Co., location of wells of ................•... 98,101, 102,133, 161 

Q. 

·Quaternary deposits, nature and distribution of .......•...... : 22,51-52 

R. 

Railroads, building of... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63, 64 

Record area, geology and deYelopmcnt of ....................... 151-154 

Record Co., elevation of wells of ... ·.; ........................... 172-173 

location of wells of. ................ , ................... 151,172-173 

Recovery Co., location of wells of................................. 106 

Redlands Co., location of-wells of .............................. ·... 163 · 

Relief map of California. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 

Roliefoftho field ................................................. 15-17 

Reserves and withdrawals, .petroleum, map showing. . . . . . . . . . . . . 68 

Reservoirs, lithological requirements of.. . . . . . . . . . . . . . . . . . . . . . . . . . 78-82 

Result Co., location of wel~s oL.................................. 98 

Rex Midway Co., location of wells of............................. 150 

Rock Co., location of wells of ..................... ,............... 98 

Rocks, nature of, influence of, on the accumulation of oil ......... 78:-82 

Ruby Co., location of wells of.................................... 145 

· Rudisill anticline, displacement along............................ 89 

Rudisill-Bamodon area, geology and development of ............ 150-151 

s. 

iS. K. D. Co., location of wells of.. ........................ :....... 117 

·.Sage-Lakeview area, geology and dE;Jvelopmcnt oL. ............. 136-139 

.St. Helens Co., location of wells of................................ 158 

.St. liaW"rence Co., location'ofwells of............................. 11.4 

.Safe Co., location of wells of. ......................... 1 ....... •. .. • 128 

.Salt Creek, section of Vaqueros formation on ridge near........... 32 

;San Andreas fault, description of.. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 61 

.San Emigdio Mountains, Etchegoin formation ili .................. 45-46 

foothills of. . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . .. .. . . . . . . . . . . 170 

rocks forming central part of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 22 

structure of ......................................... 17,56,57,60-63 

west end of, plato showing................................... 19 

:San Francisco Midway Co:, location of wells of ................ •... 98 

.san Joaquin Vi\Uey, description or.· ....................... : ..... : 1~17 

diatomaceous shale in ......... ·:·.: ................ · ........... :· 72 

:Sand made by well in the Sunset oil field, plate showing.. . . . . . . . 160 

Sands, .oil, movement of oil into .................................. 76-77 

oil, nature and position of .. · ........................ ~ ......... 10-11 

porosity of ................................................ 78-82 

position and nature of. See names of productive areas. 

source of material forming .................. ; . . . . . . . . . . . . . 80-81 

stereogram showing structure of, in sec. 36, T. 31 S., R. · 

22E.................................................. ,104 

Page. 

Shales diatomaceous, origin of petroleum in. • • • • . . . . . . . • . . . . . . . . . 70-71 

Sierra Nevada, structure of....................................... 55 

Sixteen anticline; structural relations of .•........ , ............. 158-159 

Snook Co., location of wells of.................................... 145 

Soudan Co. ,_elevation of wells of ............. :.................... 173 

location of wells of. ........................................ 101,173 

Spellacy Hill anticline, position of.. ........................... 57, 5~0 

productive areas on ............. ~ .......... 123-124, !29-130, 133-134 

Spreckles Co., location of wells of.. ... •............................ 140 

Standard Co., elevation of wells oL............... .. . . .. . . . . . . . . . 173 

flowing wells of. ................... ~. .. . . . .. . .. .. . . . . . . .. . . . . . 66 

gas wells of.................................................... 66 

location of wells of .•....... J.lO, 117,133,135,145,150,154,158,159,173 

pipe lines of. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 

water supply of.............................................. 68 

Starke, E. A., on c::trbonate waters as an indication of oil..:...... 87 

Starlight Ce., location of wells of. ; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 

State Consolidated Co., elevation of wells of:..................... 173 

location of wells of. ................................. 97,101,102, 173 

State-American Oilfields area, geology and development of ..... 10:-106 

Stereogram, construction of. ................................. ·.... 104 

Stibnite. See Antimony. 

Stockton Midway Co., location of wells of........................ 91 

Stratigraphy of-the field." ........................................ 20-54 

Stratton Water Co., location of wells of ......................... :. 120 

water supplied by ............................................ 67,68 

Stratton Water-Lockwood area, geology and development of ... 120-123 

"Stray" oil sands, occurrence of..: .............. :................ 99 

Structure of the field ............................................. 53-63 

map showing ............................................ In pocket. 

Sulphur, deposits of.............................................. 88 

Sump filled with oil from LakeYiew No. 1 gusher, October, 1910, 

plate sho\\ing........................................ 129 

Sump filled with oilfromMioceneNo.l well in 1914, platesho·;;in::. 129 

Sunset Canyon, Vaqueros formation about...................... 34 

Sunset Extension Co., location of wells of ......... :. . . . . . . . . . . . . . 161 

Sunset Mohawk Co., location of wells of. ............... ; .... ,... 145 . 

Sunset Monarch Co., location of wells of ... ·............ . . . . . . . . . . 145 

suniet oil field in 1901, plate showing. . . .. . . . . . . . . . . .. .. . . . . . . . . . 16 

in 1908, plate showing........................................ 64 

in 1914, plate showing........................................ 64 

position of oilsandsin; map showing......................... 146 

Synclines, oil sands in............................................ 161 

secondary, concentration ofoilnota.Lected by ................ 77-78 

T. 

T. W. Co., location of wells of. ............... · ..... :.............. 129 

Talara area, geology and development of. ............•... ~ ..... 123-128 

TamalpaisCo., location of wells of................................. 129 

TI!X ,.formation of. ............... : ................................ 87-88 

occurrence of................................................. 11 

plugging of oil reservoirs by................................. 85 

See also Br~a. 

Tar sands, difficulty of drilling................................... 96 

Tejon formation, age and correlation of .......... ,................ 25 

·basal part of, on Los Lobos Creek, plates showing............ 24 

nature and distribution of. ................................ 20, 23-25 

relation of, to oil pools ...... ~ ................................. 25-26 

. section of, between·Salt and Pleito creeks.................... 24 

water. See names of.produc:ive areas. stratigraphicrelationsoL........................... .. . . . . . . . 23 

.Santa Margarita formation, general nature of ..•.................. 21,42 Telephone Hills, fault in displacement and fracturing along ...... 89,94 

.lithology of ................................. : ...... ; ......... 42-43 Temblor Range, description of. .............................. ~... 17 

relations of, to petroleum ............................. . J. •• ~-- •·• 43 Etchegoin formation in ................................ .' ... : .. 46-47 

stratigraphic relations of. ................................ :... . 42 higher parts of, possibility of oil in ..... : .................•• 170-171 

useofterm .....••.•.... : ...................................... 28 structureof. ......•....................................... 55,57~ 

'Santiago Creek, springs on, water from........................... 68 surface waters of. ..................... ;....................... 67 

Vaqueros formation east of. ................................. : 29-3::? Terrace deposits, nature and distribution of •..........••..•..... 5i-'-52 

Vaqueros formation west of. •................................ 32-33 Terrace deposits along San Emigdio Creek, plate sho";ing. . . . • . • • 51 

Schultz Co., location of ~..-ells of. ...................... · ........... .' 158 Terraces near mouth of Santiago Creek, plate showing............ 50 

Scope.orthe report ........................... , ................... 14-15 on Los Lobos Creek, plate showing ..••.... ~ .................• · 50 

Scottish Oil Fields Co., location of wells or.' ......•• · ...... ' ....... ·. · 163 Tertiary system, formations 9f. .............................•..•• 23-51 

.Seaboard Co., location of wells of. ............ : ............ :...... 129 Test Oil Co., location of wells of.................................. 146 

;Section Four Co., location of wells of. •.... , ........... :.......... 163 Thirty-five anticline, position of.. .................. ~ ............ 57,5~ 

.Section Twenty-five a~:ea, geology and development of ........ : 128-133 productive areas on ................................ ; .... 136,140,-161 

.section Twenty-five Co., location of wells of .................... 129, 133 Thirty-four Hill Oil Co., loc~tion of wells of........................ 146 

.security Co., location of wells of.................................. 94 Topatopa formation, occurrence of................................ 23 

.Shale oil, gravity of._............................................. 82 Topaz Co., location of wells of.................................... 145 

pressure on .................................................. . 82 Topographic map of the Sunset-Midw_ay oil L.eld .. : . ......... In pocket.