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Full text of "Geologic formations and economic development of the oil and gas fields of California. (In four parts, including outline geologic map showing oil and gas fields and drilled areas)"

UMIVEB CALIFORNIA 

DAVIS 



STATE OF CALIFORNIA 

EARL WARREN, Governor 

DEPARTMENT OF NATURAL RESOURCES 

WARREN T. HANNUM, Director 

DIVISION OF MINES 

FERRY BUILDING, SAN FRANCISCO 

OLAF P. JENKINS. Chief 



SAN FRANCISCO] 



BULLETIN No. 118 



[APRIL 1943 



GEOLOGIC FORMATIONS 

AND 

ECONOMIC DEVELOPMENT OF THE OIL AND GAS FIELDS 

OF 

CALIFORNIA 



(In Four Parts, Including Outline Geologic Map 
Showing Oil and Gas Fields and Drilled Areas) 



PREPARED UNDER THE DIRECTION OF 

OLAF P. JENKINS 



(Reprinted September 1948) 




..<ARY 
UNIVERSITY OF CALIFORNIA 
DAVIS 



CONTRIBUTING AUTHORS 



Alice S. Allen 

H. B. Allen 

Frank M. Anderson 

E. R. Atwill 

Wm. C. Bailey 

Richard S. Ballantyne, Jr. 

Roy M. Barnes 

Roy M. Bauer 

Roy W. Bauer 

II. T. Beckwith 

Max Birkhauser 

G. S. Borden 

Glenn H. Bowes 

Charles R. Canfield 

L. S. Chambers 

C. C. Church 

Bruce L. Clark 

Thomas Clements 

Richard R. Crandall 

Charles M. Cross 

Rodman K. Cross 

Eugene L. Davis 

T. W. Dibblee, Jr. 

John P. Dodge 

E. C. Doell 

James M. Douglas 

Frank E. Dreyer 

Herschel L. Driver 

Paul H. Dudley 

J. E. Eaton 

Everett C. Edwards 

Elisabeth L. Egenhoff 

Glenn C. Ferguson 

G. S. FOLLANSBEE, Jr. 

Lesh C. Forrest 
John Galloway 
Chester M. Gardiner 
A. W. Gentry 
S. H. Gester 
Paul P. Goudkoff 
U. S. Grant IV 
S. Grinsfelder 



G. Dallas Hanna 

William C. Harrington 

Robert F. Heizer 

Gerard Henny 

Stanley C. Herold 

Leo George Hertlein 

Mason L. Hill 

Donuil Hillis 

H. D. Hobson 

W. H. Holm an 

Harold "W. Hoots 

Paul J. Howard 

Olaf P. Jenkins 

F. A. Johnson 

Harry R. Johnson 

W. S. W. Kew 

Vernon L. King 

J. M. Kirby 
Robert M. Kleinpell 
William D. Kleinpell 
Emil Kluth 
George L. Knox 
George R. Kribbs 
Max L. Krueger 
Boris Laiming 
Glen W. Ledingham 
Harry D. MacGinitie 
Charles Manlove 
Jay Glenn Marks 
John C. May 
J. II. McMasters 
Loyde H. Mf.tzner 
James H. Michelin 
Robert II. Miller 
Manley L. Natland 
Earl B. Noble 
Frank S. Parker 
J. R, Pemberton 
Petroleum World 
W. P. Popenoe 
Lawrence E. Porter 
William W. Porter II 



Ralph D. Reed 
Richard G. Reese 
Robert L. Rist 
R. G. Rogers 
E. E. Rosaire 
H. L. Scarborough 
L. F. Schombel 
R, W. Sherman 
R. R. Simonson 
Loring B. Snedden 

E. K. Soper 
Walter Stalder 
John B. Stevens 
R. E. Stewart 
T. F. Stipp 
Harry P. Stolz 
R. 0. Swayze 

N. L. Taliaferro 

C. C. Thoms 
Richard R. Tiiorup 
Frank B. Tolman 
Lester C. Uren 
W. W. Valentine 
Martin Van Couvering 

F. E. Vaughan 
Frederick P. Vickery 
William R, Wardner, Jr. 
Louis N. Waterfall 
Charles E. Weaver 

D. K. Weaver 
J. B. Wharton 
V. H. Wilhelm 

R. N. Williams, Jr. 
Robin Willis 
M. Grace Wilmarth 
W. P. Winiiam 
II. E. Winter 
Read Winterburn 
Stanley G. Wissler 
A. F. Woodward 
W. T. Woodward 
Umberto Young 



In all, 126 authors have contributed to the entire bulletin. 



m 



p~>*r> 



LETTER OF TRANSMITTAL 

To His Excellency, The Honorable Earl Warren, 
Governor of the Stale of California 

Sir: I have the honor to transmit herewith Bulletin 118 of the Division of Mines of the Department 
of Natural Resources on the "Geologic Formations and Economic Development of the Oil and Gas Fields of 
California." 

The petroleum industry in California is outstanding among our diversified mineral resources of economic 
value and utilization both in normal peace-time activities and in the present war emergency. It has accounted 
in recent years for 65 percent to 80 percent of the total value, annually, of all mineral production in this State. 

The assembling and supervision of the preparation of text and illustrations of this almost monumental 
volume have been handled by Olaf P. Jenkins, supervising geologist of the Division of Mines, with the assistance 
of his editorial assistant, Elisabeth L. Egenhoff. One hundred twenty-six geologists have contributed articles for 
this bulletin, each on a subject or area well known to him. Without this cordial and freely given cooperation of 
the men and companies in the petroleum industry, it would have been impossible for the limited staff of the 
Division of Mines to have covered the field so authoritatively and effectively. 

Walter W. Bradley, 

State Mineralogist 

San Francisco, March 11, 1943. 



PREFACE 



The theme of Bulletin 118 is geology — the guiding 
science in exploration for oil and gas. For the petro- 
leum industry of California, the greatest of all mineral 
developments in the State, it has been our aim to issue 
a useful, authentic, and up-to-date source book. This 
bulletin is also to serve as a companion to the Geologic 
Map of California, issued by the Division of Mines in 
1938, and to treat of the long and eventful sedimentary 
record of the State, especially where it concerns the 
areas which have been drilled in the quest for oil 
and gas. 

One hundred twenty-six geologists have contributed 
articles for this bulletin, each on a subject particularly 
well known to him. Maps, sections, charts, and pictures 
have been used freely to augment the text. Tndex maps, 
all reproduced on the scale of 1 :500,000, the same as that 
of the Geologic Map of California, furnish graphic 
definitions of the oil fields and their productive acreage. 
Selected citations to literature, grouped according to the 
various names applied to the areas accompany these 
index maps; together they serve as a glossary and a 
ready reference to available published data on the 
geology of the individual fields. All published rock 
formation names are briefly defined and accompanied by 
selected citations in a glossary of geologic units. The 
citations throughout the bulletin refer to one master 
bibliography which is in itself a record of the accom- 
plishments of the science and development of the petro- 
leum industry. The bulletin has been indexed so that 
the reader may readily find not only the subjects dis- 
cussed in the bulletin, but also the names of fields and 
their descriptions published elsewhere. 

Finally, in a pocket, is an economic state map. show- 
ing the locations of the oil and gas fields and other 
drilled areas. The map shows the major geologic fea- 
tures and various data of significance in the exploration 
for oil and gas. It is one of a series of economic mineral 
maps now being issued by the Division of Mines. 

Bulletin 118 has been arranged in four parts. The 
first, Development of the Industry, is of general eco- 
nomic, historic, and developmental concern. The 
second, Geology of California and the Occurrence of Oil 
and Gas, is of a fundamentally scientific nature, espe- 
cially intended to cover the problems of geologic history, 
stratigraphy, and structure. It discusses where oil is 
found in the rock formations and how it happened to 
accumulate in such extraordinary amounts. The third 
part. Descriptions of Individual Oil and Gas Fields is 
intended to give brief and ready reference to the essen- 
tial features of each area which has attracted attention 
from the standpoint of exploration. The fourth part 
is devoted to the glossary of geologic units, the master 
bibliography, and the general index to the entire bulletin. 

As the gathering of data for this volume progressed, 
the undertaking was found to be too great to handle as 
one unit, and the information too timely to withhold 
from distribution until it was all in readiness for publi- 
cation. For that reason, the bulletin was divided into 
four parts, and each part was printed as it was com- 
pleted. An issue of 4.000 copies was made, 2.000 of 
which were bundled and stored for final binding, while 



the remaining 2,000 were made available through dis- 
tribution as paper-covered pre-prints. 
PART ONE: 

Title-page date of pre-print, April 1940; date 
when first made available, October 1940. 

PART TWO : 

Title-page date of pre-print, August 1941 ; date 

when first made available September 11, 1941. 
PARTS THREE AND FOUR (issued together) : 

Title-page date of pre-print, March 1943. 
FINAL BOUND ISSUE : 

Title-page date of bound volume, April 1943. 

The individual reports for Bulletin 118 were prepared 
during a period of more than four years. The first 
manuscript was received December 30, 1937 ; the last 
was completed in the early part of 1943. The date when 
each manuscript was submitted for publication has been 
entered in a footnote at the beginning of each article, and 
the reader is cautioned always to consider this date, 
since new developments or discoveries may have taken 
place since that time. 

For many years there has been a genuine need for a 
treatise on the oil and gas resources of California. 
Previous statewide reports on this subject have long been 
out of print. 1 Geology of California, by the late Ralph 
D. Reed, 2 which served magnificently the ' purpose of 
bringing order out of chaos, so far as interpretative 
geologic history of California is concerned, is now also 
out of print. Great strides have since been made in 
new discoveries and interpretations so that it is now 
essential that a volume such as this bulletin should be 
issued to bring together our present knowledge. 

The success achieved in securing support from many 
authoritative agencies in the making of the Geologic 
Map of California, suggested the idea of employing the 
same method in preparation of this book. The result 
has been indeed gratifying. More contributions were 
received than anticipated, and the oil companies are to 
be congratulated for their generosity to science in releas- 
ing this vast wealth of information. 

Since Bulletin 118 is a composite of many separate 
articles prepared especially for this volume, its authen- 
ticity may be relied upon. We have refrained from 
abstracting or copying earlier published works, or piec- 
ing together unpublished material. Although some 
areas, therefore, are omitted from the descriptions, the 
reader is not left without a means of securing data, since 
all lmoivn references to published information are cited. 

1 Watts, W. L. Gas and petroleum yielding formations of cen- 
tral valley of California. Bulletin 3, 100 pages, 13 illustrations, 4 
maps. 1894. 

Watts, W. L. Oil and gas yielding formations of Los Angeles. 
Ventura, and Santa Barbara Counties. Bulletin 11, 94 pages. C 
maps. 31 Illustrations. 1897. 

Watts, W. L. Oil and gas yielding formations of California. 
Bulletin 19, 236 pages. GO illustrations, 8 maps, 1900. 

Trutzman, Paul W. Production and use of petroleum in Cali- 
fornia. Bulletin 32. 230 pages, 116 illustrations, 14 maps, 1904. 

Prutzman, Paul W. Petroleum in southern California. Bul- 
letin 63, 430 pages. 41 Illustrations, G maps, 1912. 

McLaughlin, R. P.. and Waring. C. A. Petroleum industry of 
California, with folio of mans (18x22). Bulletin 69, 519 pages, 13 
illustrations, 83 figures, 18 plates. 1914. 

Vander Leek. Lawrence. Petroleum resources of California, 
with special reference to unproved areas. Bulletin 89. 186 pages. 
12 figures, 6 photographs. 6 maps in pocket. 1921. 

= Reed. Ralph D. Oeologv of California. American Associa- 
tion of Petroleum Geologists, 555 pages. 60 figures, 1933. 



Vll 



Vlll 



Preface 



In addition to the long list of authors who have con- 
tributed reports for Bulletin 118, there are many other 
persons who have very kindly supported the work. 
These include the following: The Supervisor and Deputy 
Supervisors of the California State Division of Oil and 
Gas; the chief geologists and executives of the oil com- 
panies; members of geological departments of educa- 
tional institutions; individuals, research workers, and 
consultants; and many other persons particularly inter- 
ested in our success, such as the editors of the Petroleum 
World and of the Bulletin of the American Association 
of Petroleum Geologists. To all these persons and com- 
panies who have so generously contributed to make this 
bulletin a success, we wish to express our deep apprecia- 
tion. 

While this bulletin has been in press several note- 
worthy publications have appeared which are not listed 
in the Bibliography. They include general reports on 
exploration and development in California during 1941 3 ; 
reports on the natural gas reserves of the State 4 descrip- 
tions of the Paloma oil field, 5 the West Montebello oil 
field, the Wilmington oil field, 7 the Edison oil field," 



3 Dorrance, James R. California exploration and development 
in 1941. American Association of Petroleum (Geologists Bulletin, 
volume 26, number 0, pages 1135-1154, June 1 " 4 2 . 

Wiliielm, V. H. Developments in the California oil industry 
during the year 1941. American Institute of Mining and Metal- 
lurgical Engineers, retroleum Division, Petroleum Development and 
Technology, Transactions, volume 1 4(1, pages 259-270. 1942. 

* Estimate of the natural gas reserves of the State of California 
as of January 1, 1941. Case No. 4591. Special Study No. S-258. 
Railroad Commission of the State of California, and Department of 
Natural Resources, Division of Oil and Gas, 254 pages, maps, tables, 
illustrations. San Francisco, September 15, 1942. 

Estimate of the natural gas reserves of the State of California 
as of January 1, 1941 and as of January 1, 1942. Case No. 4591, 
Special Study No. S-334. Railroad Commission of the State of Cali- 
fornia and Department of Natural Resources, Division of Oil and Gas. 
29 pages, map. San Francisco, November 15, 1942. 

B Geis, W. H. A plan for operation of the Paloma field. Amer- 
ican Institute of Mining and Metallurgical Engineers, Petroleum 
Division Petroleum Development and Technology Transactions, vol- 
ume 146, pages 83-88, 1942. 

Wood, James T. Jr. Geology and development of the Paloma 
field, Kern County, California. American Institute of Mining and 
Metallurgical Engineers, Petroleum Development and Technology, 
Transactions, volume 146, pages 76-82, 1942. 

" Stolz, H. P. West Montebello oil field and application of the 
state gas law. California Department of Natural Resources, Division 
of Oil and Gas, Summary of Operations, California Oil Fields, volume 
25, pages 5-23, 1940. 

7 Crown, Walter J. Wilmington oil field. California Depart- 
ment of Natural Resources. Division of Oil and Gas. Summary of 
Operations, California Oil Fields, volume 26, pages 5-11, 1941. 

•Kasline, Fred E. Edison oil field. California Department of 
Natural Resources. Division of Oil and Gas, Summary of Operations, 
California Oil Fields, volume 26, pages 12-18, 1941. 



the Midway-Sunset oil field," the Imperial carbon-dioxide 
gas field, 10 and Humboldt County 11 ; a monograph on 
the Franciscan-Knoxville problem 12 ; papers on Mar- 
tinez formation, 13 and the Eocene in western Santa Ynez 
Mountains, with map 14 ; a discussion of the Crocker Flat 
landslide area 15 ; a description of dam sites in Cali- 
fornia I6 ; a discussion and map of the Ventura region 1T ; 
and a paper on Marysville Buttes. 18 

It is hoped that this volume will serve as a guide to 
a better understanding of the geology of California and 
of the ways of developing and conserving the vast min- 
eral resources with which the state has been so gener- 
ously endowed. 

Olaf P. Jenkins, 

Ferry Building, San Francisco. 

March 10, 1943. 



9 Ayars, R. N. Webster area of Midway-Sunset oil field. Cali- 
fornia Department of Natural Resources, Division of Oil and Gas, 
Summary of Operations, California Oil Fields, volume 26, pages 19-24, 
1941. 

10 Bransford, Jas. G. Imperial carbon-dioxide gas field. Cali- 
fornia Oil World and Petroleum Industry, July, pages 13-14, 1942. . . . 
California Department of Natural Resources, Division of Mines, Cali- 
fornia Journal of Mines and Geology, State Mineralogists Report 38, 
no. 2, April, pages 198-201, 1942. 

11 Averill, Chas. V. Mineral resources of Humboldt County. 
California Department of Natural Resources, Division of Mines, Cali- 
fornia Journal Mines and Geology, State Mineralogist's Report 37, 
pages 499-528 ; natural gas, pages 520-521 ; petroleum, 521-526 ; 1941. 

■-Taliaferro, Nicholas B., Franciscan-Knoxville problem. Amer- 
ican Association of Petroleum Geologists Bulletin, volume 27, no. 2, 
February, pages 109-219, 1943. 

13 Watson, Elizabeth A. Age of the Martinez formation of 
Pacheco syncline, Contra Costa County, California. The American 
.Midland Naturalist, volume 28, no. 2. pages 451-456, September, 1942. 

■'Kelley, Frederic Richard. Eocene stratigraphy in western 
Santa Ynez Mountains, Santa Barbara County, California. Amer- 
ican Association of Petroleum Geologists Bulletin, volume 27, no. 1, 
January, pages 1-19, 1943. 

15 Simonson, Russell R., and Krueger, Max L. Crocker Flat land- 
slide area, Temblor Range, California. American Association of 
petroleum Geologists Bulletin, volume 26, no. 10, October, pages 
1608-1631, 8 figures. 1942. 

16 Nickell, F. A. Development and use of engineering geology. 
American Association of Petroleum Geologists Bulletin, volume 26, 
no. 12, December, pages 1797-1826, 1942. 

17 Putnam, William C. G«omorphology of the Ventura region, 
California. Geological Society of America Bulletin, volume 53, pages 
691-754, 5 plates, 11 figures, 1942. 

18 Stalder, Walter. 1941 supplement to Sutter (Marysville) 
Buttes development, Sutter County, California, American Association 
of Petroleum Geologists Bulletin, volume 26, no. 5, May, pages 852- 
864, 1942. 



CONTENTS 

PART ONE— DEVELOPMENT OF THE INDUSTRY "! 

CHAPTER I— Development and Production 2 

Economics of the Oil and Gas Industry of California, by J. R. Pemberton 3 

Taxation and Its Relation to Development and Production, by Granville S. Borden 15 

Historical Production Chart, by II. L. Scarborough 16-17 

Stocks Chart, by II. L. Scarborough 17 

Shipments Chart, by II. L. Scarborough 18 

Significant Statistics Characteristic of Crude Oil Production of California, by Win. R. Wardner, Jr 20 

Analysis of California Petroleum Reserves and Their Relation to Demand and Curtailment, bv Wm. 

R, Wardner, Jr .' 26 

Natural Gas Fields of California, by Roy M. Bauer and John F. Dodge 33 

CHAPTER II— Exploration 37 

Development, of Engineering Technique and Its Effect Upon Exploration for Oil and Gas in California, 

by Lester C. Uren 39 

Mechanics of California Reservoirs, by Stanley C. Herold 63 

Geophysical Studies in California, by F. E. Vaughan 67 

Geochemical Prospecting for Petroleum, by E. E. Rosaire 71 

CHAPTER III— Early History 73 

Aboriginal Use of Bitumen by the California Indians, by Robert F. Heizer 74 

History of Exploration and Development of Gas and Oil in Northern California, by Walter Stalder 75 

PART TWO— GEOLOGY OF CALIFORNIA AND THE OCCURRENCE OF OIL AND GAS 81 

CHAPTER IV— Introduction to the Geology 82 

Geomorphic Provinces of California, by Olaf P. Jenkins 83 

Salient Geologic Events in California and Their Relationship to Mineral Deposition, by Olaf P. Jenkins 80 

Position of the California Oil Fields as Related to Geologic Structure, by Ralph D. Reed 95 

CHAPTER V— Geologic History and Structure 98 

California's Record in the Geologic History of the World, by Ralph D. Reed 99 

Geologic History and Structure of the Central Coast Ranges of California, by N. L. Taliaferro 119 

CHAPTER VI— Paleontology and Stratigraphy 164 

Characteristic Fossils of California, by G. Dallas ITanna and Leo George Hertlein 165 

Descriptions of Foraminifera, by C. C. Church 182 

Synopsis of the Later Mesozoic in California, by Frank M. Anderson 183 

Notes on California Tertiary Correlation, by Bruce L. Clark 187 

Eocene Foraminiferal Correlations in California, by Boris Laiming 193 

Sequence of Oligocene Formations of California, by Lesh C. Forrest 199 

Correlation Chart of the Miocene of California, by Robert M. Kleinpell; Introduction, by William D. 

Kleinpell I ' 200 

Pliocene Correlation Chart, by U. S. Grant IV and Leo Geoi-jje Hertlein 201 

The Pleistocene in California", by J. E. Eaton 203 

CHAPTER VII— Occurrence of Oil 208 

Stratigraphic Relations of the Producing Zones of the Los Ansreles Basin Oil Fields, bv Stanlev G. 

Wissler . . 1 ' 209 

Correlation of the Oil Fields of the Santa Maria District, by Stanley G. Wissler and Frank E. Dreyer_. 235 4 

Correlation of Oil Field Formations on East Side Sin Joaquin Valley, by Glenn C. Ferguson 239 

Correlation of Oil Field Formation on West Side of San Joaquin Vallev. by Paid P. Goudkoff 247 

Origin, Migration, and Accumulation of Oil in California, by Harold W. Hoots 253 

PART THREE— DESCRD7TIONS OF INDIVIDUAL OIL AND GAS FIELDS 277 

Citations to Selected References, by Elisabeth L. Egenhoff (distributed throughout Part Three) 278 

CHAPTER VIII— Los Angeles Basin and Southernmost California 281 

Los Angeles Citv Oil Field, bv E. K. Soper 282 

Salt Lake Oil Field, bv E. K. Soper 284 

Beverlv Hills Oil Field, bv E. K. Soper 287 

Whittier Oil Field, bv W. IT. Holman 288 

Playa del Rev Oil Field, bv Lovde II. Metzner , 292 

El Segundo Oil Field, by Richard G. Reese 295 

Lawndale Oil Field, by Richard G. Reese 297 

Torrance Oil Field, by Eugene L. Davis 298 

ix 



Contents 

Pack 

Wilmington Oil Field, by Read Winterburn , 301 

Inglewood Oil Field, by Herschel L. Driver 306 

Potrero Oil Field, by Robin Willis and Richard S. Ballantyne, Jr. 310 

Dominguez Oil Field, by S. Grinsfelder 318 

Long Beach Oil Field, by Harry P. Stolz 320 

Seal Beach Oil Field, by Glenn H. Bowes 325 

Huntington Beach Oil Field, by D. K. Weaver and V. H. Wilhelm " 329 

Newport Oil Field, by Frank S. Parker 332 

West Montebello Area of the Montebello Oil Field, by Harry P. Stolz, and A. F. Woodward 335 

Montebello Area of the Montebello Oil Field, by Richard G. Reese 340 

Santa Fe Springs Oil Field, by H. E. Winter , 343 

West Coyote Area of the Coyote Hills Oil Field, by Richard G. Reese 347 

East Coyote Area of the Coyote Hills Oil Field, by Paul H. Dudley 349 

Yorba Linda Area of the Coyote Hills Oil Field, bv Frank S. Parker 355 

Richfield Area of the Richfield Oil Field, by Chester M. Gardiner 357 

Kraemer Area of the Richfield Oil Field, by Richard G. Reese 361 

Chino Area, by Max L. Krueger 362 

Cretaceous Formations of the Northern Santa Ana Mountains, by W. P. Popenoe 364 

Southwestern San Diego County, by Leo George Hertlein and U. S. Grant, IV 36'J 

CHAPTER IX— Ventura Basin and Transverse Ranges 370 

Gaviota-Concepcion Area, by William W. Porter II 372 

Capitan Oil Field, by George R. Kribbs 374 

Goleta Oil Field, by Frederick P. Vickerv 377 

Elwood Oil Field, by Mason L. Hill '_ 380 

La Goleta Gas Field, by R. O. Swayze 384 

Summerland Oil Field, by Emil Kluth 386 

Rincon Oil Field, by R. E. Stewart 387 

Ventura Avenue Oil Field, bv C. C. Thorns and Wm. C. Bailev 391 

Santa Paula Oil Field, by Louis N. Waterfall 394 

Sespe Oil Field, by Thomas Clements 395 

Piru Oil Field, by II. D. Hobson 400 

Southern Mountain Oil Field, by Loring B. Snedden 404 

Bardsdale Area of the Bardsdaie Oil Field, by Loring B. Snedden 406 

Shiells Canyon Area of the Bardsdale Oil Field, bv Loring B. Snedden 407 

Del Valle Oil Field, bv R. W. Sherman 408 

Newhall Oil Field, bv W. S. W. Kew 412 

Simi Oil Field, bv T. F. Stipp , 417 

Conejo Oil Field, by John C. May 424 

CHAPTER X— Santa Maria Basin and Southern Coast Ranges 425 

Lompoc Oil Field, bv T. W. Dibblee, Jr 427 

Casmalia Oil Field, by William W. Porter II 430 

Santa Maria (Orcuttj Oil Field, by F. E. Dreyer , 431 

West Cat Canyon Area of the Cat Canyon Oil Field, by Charles Manlove 432 

East Cat Canyon Area of the Cat Canyon Oil Field, by Rodman K. Cross 435 

Gato Ridge Area of the Cat Canvon Oil Field, bv Rodman K. Cross 438 

Santa Maria Valley Oil Field, by Charles R. Canfield 440 

Geology of Huasna Area, by N. L. Taliaferro 443 

Huasna Area Development, by Vernon L. King 448 

Arroyo Grande (Edna) Oil Field, by Max L. Krueger 450 

Caliente Range, Cuyama Valley, and Carrizo Plain, by J. E. Eaton 453 

Rradley-San Miguel District, by N L. Taliaferro 456 

Type Locality of the Vaqueros Formation, by Richard R, Thorup 463 

Soledad Quadrangle, by L. F. Schombel 467 

Cantua-Vallecitos Area, by E. R, Atwill 471 

Sargent Oil Field, by James Michelin 475 

Moody Gulch Oil Field, bv Max L. Krueger 477 

Halfmoon Bay District, by Richard R. Crandall 478 

Mount Diablo Region, by Charles M. Cross 481 

CHAPTER XI— San Joaquin Valley and Bordering Foothills 482 

Geologic Horizons of Oil and Gas Fields of San Joaquin Valley and Farther North, by Paul J. Howard. 483 

Coalinga Oil Field, by Max Birkhauser 484 

Coalinga East Extension Area of the Coalinga Oil Field, by L. S. Chambers 486 



Contents xi 

Page 

Kettleman Hills Oil Fields, by John Galloway 491 

Lost Hills Oil Field, by G. S. Follansbee, Jr 494 

Devils Den Oil Field, by Martin Van Couvering and II. B. Allen 496 

Belridge Oil Field, by J. B. Wharton 502 

Temblor Oil Field, by R. R. Simonson 505 

MeKittrick Front and Cymric Areas of the McKittrick Oil Field, by E. R, Atwill 507 

McKittrick Area of the McKittrick Oil Field, by John B. Stevens 510 

Elk Hills Oil Field (U. S. Naval Petroleum Reserve No. 1), by Lawrence E. Porter 512 

Ruena Vista Hills Area of the Midway-Sunset Oil Field, by J. IT. McMasters 517 

North Midway Area of the Midway-Sunset Oil Field, by W. T. Woodward 519 

Republic Area of the Midway-Sunset Oil Fiel 1, by Umberto Young 522 

Williams and Twentv-Five Hill Areas of the Midway-Sunset Oil Field, by Donuil Hillis 

and W. T. Woodward 526 

Gibson Area of the Midwav-Sunset Oil Field, bv W. T. Woodward 530 

Wheeler Ridge Oil Field, by S. H. Gester 532 

Type Locality of the Tejon Formation, by Jay Glenn Marks 534 

Dudley Ridge Gas Field, by Gerard Denny 539 

Semitropic Gas Field, by W. W. Valentine 542 

Buttonwillow Gas Field! bv L. S. Chambers 543 

Canal Oil Field, bv R. N Williams, Jr 546 

Strand Oil Field, bv Charles M. Cross 548 

Ten Section Oil Field, bv A. W. Gentry 549 

Trico Gas Field, by E. C. Doell 551 

Waseo Oil Field, bv Rov M. Barnes 553 

Rio Bravo Oil Field, bv Earl B. Noble 556 

Greeley Oil Field, by W. P. Winham 559 

Fruitvale Oil Field, by Robert H. Miller and Glen W. Ledingham 562 

Mountain View Oil Field, by Robert IT. Miller and Glenn C. Ferguson -- 565 

Kern Front Area of the Kern River Oil Field, by Everett C. Edwards 571 

Kern River Area of the Kern River Oil Field, by John B. Stevens 575 

Edison Oil Field, by Everett C. Edwards 576 

Round Mountain Oil Field, by R, G. Rogers 579 

CHAPTER XII— Northern San Joaquin Valley, Sacramento Valley, and Northern Coast Ranges 584 

Tracy Gas Field, by H. T. Beckwith 586 

McDonald Island Gas Field, bv George L. Knox 588 

■Rio Vista Gas Field, bv E. K. Soper 591 

Potrero Hills Gas Field, bv Frank B. Tolman 595 

Fairfield Knolls Gas Field, by J. M. Kirby 599 

Rumsev Hills Area, bv J. M. Kirby 601 

Sites Region, bv J. M. Kirbv 606 

Willows Gas Field, by R. N. Williams, Jr 609 

Marysville Buttes (Sutter Buttes) Gas Field, by Harry R. Johnson 610 

Berryessa Valley, by F. M. Anderson 616 

Paskenta Region, by Robert L. Rist and William C. Harrington 619 

Duxbury Point Rep-ion, by James M. Douglas 621 

Petaluma Region, by F. A. Johnson 622 

Point Arena-Fort Ross Region, by Cliarles E. Weaver 628 

Central and Southern Humboldt County, by Harry D. MacGinitie 633 

CHAPTER XIII— Tabulated Data on Wells Drilled Outside of the Principal Oil and Gas Fields 636 

Tabulated Data on Wells Drilled Outside of the Principal Oil and Gas Fields. Assembled Largely from 

Data of the Petroleum World 637 

PART FOUR— GLOSSARIES, BIBLIOGRAPHY, AND INDEX 665 

CHAPTER XIV— Glossary of the Geologic Units cf California -- 666 

Glossary of the Geologic Units of California, Compilation Based Largely on the Work of M. Grace Wil- 

marth, and Alice S. Allen. Abstracted and Revised by Olaf P. Jenkins 667 

CHAPTER XV— List of Publications Cited Throughout Bulletin 118 688 

List of Publications Cited Throughout Bulletin 118, by Elisabeth L. Egenhoff 689 

CHAPTER XVI— Index to Bulletin 118 721 

Index to Bulletin 118 722 



Plate I. 



Plate 
Plate 



II. 

III. 



PLATES 

Between 
Pages 
Historical chart, showing crude oil produc- Plate IV. 

tion of California and significant historical 

events 16- 17 

Geologic structure sections across central 

Coast Ranges of California 162-16."? 

Chart showing sequence of Oligncene forma- Plate VI. 

tions in California 198-100 



Between 
Pages 
Columnar sections of middle Tertiary stages 

and zones of California 200-201 

Straight-line correlation chart of Los Angeles 

Basin oil fields 234-235 

Map of central and southern California show- 
ing oil and gas fields 274-27. r > 



MAP 

Outline geologic map of California showing 
oil and gas fields and drilled areas. Eco- 
nomic Mineral Map of California No. 2, Oil 
and Gas, 1941 In pocket 



Fig. 

Fig. 
Fig. 
Fig. 
Fig. 4A. 

Fig. 4B. 
Fig. 5. 
Fig. 6. 

Fig. 
Fig. 

Fig. 



FIGURES 

Page 

1. California crude oil production by years and total Fig. 27. 
cumulative production 4 Fig. 27A. 

2. Historical record of California wells by years 9 Fig. 27B. 

3. Stocks inside Pacific Coast territory 17 

4. Shipments from Pacific Coast territory 18 Fig. 28. 

Comparative values of total mineral production. 

California, 1848-1938 19 Fig. 29. 

Total world petroleum production, 1900-1037 19 

California: reserves and crude production 28 Fig. 30. 

California : underground reserve supply of crude 

petroleum, 1925-1938 29 Fig. 31. 

7. California: depletion of reserves, 1925-1938 29 Fig. 32A. 

8. California : years of future supply to balance Fig. 32B. 
demand of crude petroleum 29 Fig. 33. 

9. California : future crude reserve discoveries 
required to supply the demand for n years at 
which time a shortage is indicated 30 

Fig. 10. California: reserves remaining at the end of iilli 

year when a shortage has been reached 30 Fig. 33F. 

Fig. 11. Increase and decrease in demand at a constant Fig. 34. 

rate of change, from present 600,000 bbls. per day. 30 

Fig. 12. Monthlv California natural gas production ami Fig. 35. 

utilization, 1923-1939 34 

Fig. 13. Yearly California natural gas production and utili- Fig. 36. 

zation, 1906-1939 34 

Fig. 13A. Index map showing locations of oil fields and dis- Fig. 37. 

tricts in California 38 

Fig. 14. Aerial photographic map of Kettleman Hills 41 

Fig. 15. California-type standard cable drilling rig 42 Fig. 38. 

Fig. 16. California-type combination drilling rig 43 

Fig. 17. A California-type rotary drilling rig 44 Fig. 39. 

Fig. 18A. Modern steel derrick of the type used in the Cali- 
fornia fields for deep drilling by the rotary method 45 

Fig. 18B. Hoisting gear and rotary swivel suspended in the '' '-■ 4( • 

derrick •*> 

Fig. 19. Interior view of rig. Modern draw-works and 

rotary table equipped with under -floor drive 46 1! - 

Fig. 20. Examples of modern rotary core barrels. (A) 

Hughes core bit equipped with hard formation cut- p. fr ^ 

ter head. (B) Elliott rotary core drill 47 

Fig. 21. Types of rotary drilling bits (A to S) 49 

Fig. 22. Power plant for modern rotary drilling rig 50 pj„ ^ 

Fig. 23. Well-cementing equipment permanently mounted 

on motor truck 51 y IK n 

Fig. 24. Map showing course of a crooked well 5(1 

Fig. 25. Vertical section showing deflection of a well from Fig, 45. 

the vertical 57 

Fig. 26. Formation tester 511 



Page 

Sehlumberger electrical log of a well 60 

The Drake well, Pennsylvania, 1S63 62 

Recent photograph of Pico No. 4 well, Pico Can- 
yon, near Newhall 62 

Oross-seetion showing Temblor formation, from Tar 

Canyon to Shell Armstrong well No. 1 63 

Daily production record for 1929 of Kettleman 

Hills discovery well 64 

Recomputed production record for 1929 of Kettle- 
man Hills discovery well 64 

"Lines of flow into two interfering wells . . ." 65 

Geologic structure of San Joaquin Valley 68 

Geologic section across Santa Maria Valley 68 

Geochemical well logs : A. Dry and abandoned 
well; B. Producing well; C. Theory of halo forma- 
tion over structural trap; D. Topsoil analysis 
map — wax halo; E. Subsoil analysis map — Ethane 

and Propane halo 72 

Rancho la Brea tar pit, Los Angeles 73 

Asphaltum deposits known to have been used by 

Indians 74 

Dipping oil from the historic Union Mattole Oil 

Company well. 1035 80 

Relief map of California showing the geomorphic 

provinces as related to the topography 84 

Outline map of California showing the geomorphic 
provinces as related to the distribution of commer- 
cial mineral deposits 85 

Map of California showing intensity of average 

precipitation 88 

Chart giving list of commercial minerals produced 
in California, and showing how each county has 

contributed to this production SO 

Graph showing comparative total values of groups 
of commercial minerals produced in California. 

1848-1938 SO 

Diagram to give the idea of "looking back in geo- 
logic time." The salient events in the geologic his- 
tory of California are also briefly outlined 90 

Chart, drawn on logarithmic scale, to show relative 
importance of the various commercial minerals pro- 
duced in California 93 

Map showing size and dimensions of California 

and its 5S counties 94 

Generalized stratigraphic column of the Coast 

Ranges showing positions of major oil zones 95 

Map showing positions of the oil and gas fields of 
southern California in relation to geologic structure 
and paleogeography 96 



XU 



F I Ci U I! E s 



Xlll 



Fig. 46. 

Fig. 47. 

Ffe. 48. 

Fig. 40. 

Fig. 50. 

Fig. !51. 



Fig. 52. 

FiR. 53. 

Fig. r,4. 

Fig. 55. 

Fig. 50. 



Fir. 57. 



FiR. 



">s. 



FiR. 59A. 
FiR. r.OR. 

FiR. 00. 

FiR. 61. 

FiR. 02. 

FiR. 03. 

Fig. 04. 

Fig. 65. 

FiR. 60. 

FiR. 07. 

FiR. OS. 

Fig. 00. 

Fig. 70. 

Fig. 71. 

Fig. 72. 



Fig 



73. 



Fig. 74. 

FiR. 75. 

FiR. 70. 

Fig. 77. 

Fig. T8. 

Fig. 70. 

FiR. SO. 

FiR. SI. 

Fig. SL>. 



Page 
Comparative columnar sections of the Paleozoic in FiR. S3. 

California and Arizona 00 

Map showing some of the possible geographic con- FiR. 84. 

ditions of the Paleozoic 101 

Columnar section of the Carboniferous in northern FiR. So. 

California 102 FiR. SO. 

Columnar section of the Triassic of Nevada 105 Fig. R7A. 

Columnar section of the Triassic of California 105 

Diagram of Jurassic-Lower Cretaceous paleogeo- 
graphy, showing development of structure in the 

Great Valley 110 Fig. S7B. 

Paleogeographic map of the lower Palcogenc 113 

Paleogeographic map of the upper Paleogene 114 

Paleogeographic map of the lower Neogene 115 

Paleogeographic map of the upper NeoRene 110 '' 'R- 88- 

Map of the central Coast RanRcs of California 
showing principal mountain ranges and the posi- 
tion of structure sections 120 **8- °"- 

Map of central Coast Ranges showing location of 
U. S. Geological Survey topographic quadrangles 

and position of structure sections 122 

Ideal section, showing the effect of late upper Fig. 00. 

Miocene anticlinal warping on the localization of 

the marginal overturned folds and thrusts oh the * 1 B- •'•• 

two sides of Castle Mountain Range 151 

A well exposed anticline in the northern Coast 
Ranges, with an oil derrick on its crest. Looking 

northwest toward Point Arena 103 

A typical view in the central Coast Ranges, show- „„ 

ing landslide topography of the Franciscan in the 
foreground. looking south across Peach Tree 

Valley 103 

(1 to 25) Paleozoic, Triassic, and Jurassic fossils j,ij„ 04 

of California 167 

(1 to 22) Cretaceous and Upper Jurassic fossils 

of California 100 jj>j„ 0,5 

(1 to 33). Eocene, Oligocene, and Miocene fossils 

of California .1 171 pig. <)<3A.} 

(1 to 24) Miocene fossils of California 1":'. 0GB. J 

(1 to 20) Miocene, Pliocene, and Pleistocene fos- j-j™ 07. 

sils of California 175 

(1 to 18) Pliocene fossils of California 177 pji, 9g 

(1 to 21) Diatoms (Cretaceous to Recent) of 

California 170 pjg 99A.} 

(1 to 40) Foraminifera (Cretaceous to Pliocene) 90B.J 

of California 1R1 pj K . 100. 

Columnar section of the Knoxville series (Upper 

Jurassic) and the Shasta series (Lower Cretace- FiR. 101. 

ous) of California 184 

Columnar section of the Chieo series < Upper Cre- FiR. 102. 

taceous) of California 185 

Basal conglomerate of the Lower Cretaceous Shasta 

series 186 Fig. 103. 

Typical Knoxville (Upper Jurassic) shales 186 

General correlation chart of the Cenozoic of Cali- Pig- 104. 

fornia 180 Fig. 1° 5 - 

Outline map of California showing the meridians 

and base lines, together with the numbering of Fig. 100. 

townships and ranges 102 

General correlation chart of the Eocene 193 '' '*-' ln '' 

Chart showing distribution of Eocene foraminiferal 

assemblages 194 jp B - ™Jj- 

Index map showing location of Eocene sections 195 *!"'' *" 

Columnar correlations: Cantua Creek, north of Mt. ' ' 

Diablo, and Simi Valley 106 

Columnar correlations: Cantua Creek, Ciervo '' '"■ *■"■ 

Hills, and south of Pauoche Creek 106 

Columnar correlations: Oil City Coalinga, Coa- *"' s - "■*• 

linga Nose field, and Kettleman Hills field 100 

Columnar correlations : Oil City Coalinga, Coal P ' s ' *■*"■ 

Mine Canyon west of Coalinga, and Reef Ridge P 'R- 114 - 

south of Big Tar Canyon 197 

Columnar correlations: Standard Oil Co. Hooper P'S- US- 

Well No. 1, south of Panoche Creek, and east of 

Tecuya Creek 197 Fig. 116. 

Columnar correlations: north of Mt. Diablo, Rio Fig. 117. 

Vista field, and Vaea Valley 197 Fig. US. 



Paok 
(1 to 7) Some characteristic Eocene Foraminifera 

from California 19S 

Index map showing location of Oligocene sections 

shown on Plate III 199 

Generalized correlation chart of the Pliocene 202 

Correlation chart of the Pleistocene of California.. 205 
Aerial view of outcropping Tertiary strata dipping 
east. Cretaceous rocks exposed in the distance, 
upper left corner. Location : Kreyenhagen Hills, 

west of Kettleman Hills 207 

Aerial view, northeastward, across the Los Angeles 
Basin showing Santa Fe Springs oil field in the 
foreground and the San Gabriel Mountains and 

part of the Transverse Ranges in the distance 207 

Correlated stratigraphic sections of Playa del Rey, 
El Segundo, Torrance, and Wilmington (west) oil 

fields 210 

Correlated stratigraphic sections of Inglewood, 
Potrero, Rosecrans, Dominguez, Long Beach (com- 
posite), Seal Beach, and Huntington Beach (old 

field) oil fields 210 

Stratigraphic variation chart : Torrance, Domin- 
guez, and Montebello (west) oil fields 226 

Stratigraphic variation chart: Wilmington (west), 
Long Beach (south of fault), and Santa Fe 

Springs oil fields 226 

Stratigraphic variation chart: Playa del Rey, El 
Segundo, Torrance, and Wilmington (west) oil 

fields 227 

Stratigraphic variation chart: Inglewood, Potrero, 
Rosecrans, Dominguez, Long Beach (south of 
fault), Seal Beach, aud Huntington Beach (old 

field) oil fields 228 

Stratigraphic variation chart: Montebello (west), 
Santa Fe Springs, West Coyote, East Coyote 

(composite), and Richfield oil fields 229 

Straight-line correlation chart of the Santa Maria 

district oil fields 238 

Straight-line correlation chart of east side of San 

Joaquin Valley oil fields 240-241 

(1 to 4) Tertiary Foraminifera from oil field 

formations, east side San Joaquin Valley 245 

(1 to 10) Tertiary Foraminifera from oil field 

formations, east side San Joaquin Valley 240 

Straight-line correlation chart of the west side San 

Joaquin -Valley oil fields 238-249 

Index map to figure 00, showing location of west 

side San Joaquin Valley oil fields 240 

(1 to 5) Tertiary Foraminifera from oil field 

formations, west side San Joaquin Valley 252 

Topographic map of sea floor off southern Cali- 
fornia, showing distribution of sediments and rock 

bottom 254 

Map showing distribution of nitrogen in Recent 

sediments off southern California 255 

Relief model of the Philippine region 256 

Relief model of California showing oil-producing 

districts 265 

Geologic section across southern San Joaquin 

Valley 266 

Geologic section along East Coalinga anticline and 

Kettleman North Dome 268 

Map of oil and gas fields of San Joaquin Valley 271 

Map of oil and gas fields of Los Angeles Basin 272 

Chart showing stratigraphic distribution of oil 

zones in Los Angeles Basin 273 

Map of oil and gas fields of the Santa Barbara- 
Ventura district 274 

Map of oil and gas fields of the Santa Maria dis- 
trict 275 

Geologic section across Santa Maria Valley field.. 275 
Aerial view of the east flank of the Pico anticline 

south of Santa Clara River 276 

Aerial view of the Santa Maria Basin, looking 

west. Wells south of Orcutt in the foreground 270 

Los Angeles oil field : geologic map and section 283 

Salt Lake oil field : structure map 280 

Beverly Hills oil field: structure map 287 



XIV 



Figures 



Fi K . 119. 

Fig. 120. 

Fig. 121. 

Fig. 122. 

Fig. 123. 

Fig. 124. 

Fig. 125. 
Fig. 126. 
Fig. 127. 
Fig. 128. 

Fig. 129. 
Fig. 130. 
Fig. 131. 
Fig. 132. 
Fig. 133. 

Fig. 134. 
Fig. 135. 

Fig. 136. 
Fig. 137. 
Fig. 138. 

Fig. 139. 
Fig. 140. 



Fig. 141. 
Fig. 142. 



Fig. 143. 
Fig. 144. 

Fig. 145. 

Fig. 146. 
Fig. 147. 
Fig. 148. 
Fig. 149. 
Fig. 150. 
Fig. 151. 
Fig. 152. 
Fig. 153. 
154. 



'ig. 



F 

F 

Fig 

Fig. 

Fig. 

Fig. 

Fig. 

Fig. 

Fig. 



. 155. 
. 156. 

157. 

158. 

159. 

160. 

161. 

162. 

163. 



Fig. 164. 
Fig. 165. 
Fig. 166. 



Fig. 167. 
Fig. 168. 
Fig. 169. 



Page 

Whittier oil field: columnar section 288 Fig. 170. 

Whittier oil field: structure section 289 Fjg. 171. 

Whittier oil field: structure map 289 Fig. 172. 

Playa del Rey oil field: structure map 293 

Playa del Rey oil field: composite section 293 Fi". 173. 

El Segundo oil field : map, contours on top of g^_ J74 

schist; generalized section 296 pj B " 17,-, 

Torrance oil field: ideal stratigraphic column 299 y lf , 57(5 

Wilmington oil field: structure map 302 y IK 177 

Wilmington oil field : cross-section 303 ■&:„' 170' 

Inglewood oil field : structure map ; cross-sections ; 

correlation of zones 307 ™_ -i- ( ( 

Potrero oil field: structure map 312 

Potrero oil field: structure sections 313 T ,,-, r 1Rn 

Potrero oil field: Schlumberger logs 314 ' 

Dominguez oil field : structure map 319 

Long Beach oil field: structure map; ideal sec- 
tions: type log of crestal area 321 e ' 

Long Beach oil field: production graphs 323 „. 1RO 

Seal Beach oil field : topography and subsurface '] p ' Vl"' 

structure 326 s ' 

Seal Beach oil field : geologic sections 327 

Seal Beach oil field: columnar section 328 Fig- ' 

Huntington Beach oil field : topographic map ; Fig. 18 5. 

cross-section 330 Fig. 186. 

Newport oil field : columnar section ; structure map 333 
Montebello oil field : generalized structure map, Fig. 187. 
showing relationship of "old" Montebello, East Fig. i8S - 
Montebello, and West Montebello fields; ideal sec- 
tions through the West Montebello oil field 337 Fig. I s9 - 

Montebello oil field : generalized longitudinal section 341 

Santa Fe Springs oil field : structure map ; dia- Fig. 190. 

grammatic transverse section; ideal column at top Fig. 191. 

of structure 34,-, Fig. 192. 

East Coyote (East Coyote Hills) area of the Coy- 
ote Hills oil field: standard stratigraphic section.. 350 Fig. 193. 
East Coyote (East Coyote Hills) area of the Coy- Fig. 194. 

ote Hills oil field : geologic section across Hualde Fig. 195. 

dome 352 Fig. 196, 

East Coyote (East Coyote Hills) area of the Coy- Fig. 197. 

ote Hills oil field: subsurface structure 353 Fig. 198. 

East Coyote (East Coyote Hills) area of the Coy- Fig. 199. 

ote Hills oil field: geologic map 353 

Yorba Linda area (Yorba Linda oil field) area Fig. 200. 

of the Coyote Hills oil field: structure map 356 Fig. 201. 

Richfield area of the Richfield oil field : ideal g<jg 202 

graphic log 358 Fi „ 203! 

Richfield area of the Richfield oil field : structure 

map; index map 359 Fig 004. 

Chino fault area : structure map ; type log ; cross- 
section 363 Fi „ 205. 

Northern Santa Ana Mountains : geologic map of 

Upper Cretaceous deposits 365 y , onr 

Southwestern San Diego County: geologic map; y ' ^q-' 

cross-section 368 (.■«»■ 

Capitan oil field : cross-section of coastal fault .,■ on o 

block 374 " 

Capitan oil field : structure map ; ideal cross-sec- ,,. oft q 

tion ; lithologic section 374 '']*' ." .' ' 

Goleta oil field: generalized geologic map 378 1,1 s ' "' ' 

Elwood oil field: stratigraphy and oil horizons 381 Jp e " ~?i" 

Elwood oil field: structure map 382 }',!*"'' 01 ~> 

La Goleta gas field : cross-section ; structure map. 385 :',! K ' ~y.'[' 

Rincon oil field: structure map 380 "' 

Ventura Avenue oil field: type stratigraphic column 392 _ 

Santa Paula oil field: map of producing areas 394 "' 

Sespe area: geologic map; map of fields 397 „ 

Sespe Cieek-Piru Creek area : sketch map showing 

locations of columnar sections and base of Nigger 

Canyon sand 401 " - 

Piru district: surface sections 402 .,. ,,.„ 

Pirn district : subsurface sections 403 p. " 7,*q 

South Mountain, Bardsdale, and Shiells Canyon oil 

fields: geologic map of Oakridge anticline; diagram- p:„ 22O 

malic section 405 y t 7, 221 

Del Valle oil field : Section E, well logs 408 

Del Valle oil field : structure map 409 Fig. 222. 

Del Valle oil field : Section O, geologic section 410 



Page 

Newhall oil field: map 414 

Newhall oil field: cross-section 415 

North side of Simi Valley : aerial photographic and 

geologic map 418 

North side of Simi Valley: block diagram 419 

North side of Simi Valley: geologic sections 420 

Simi oil field: map 421 

Simi oil field: section 421 

Lompoc oil field: structure map; columnar section 428 
West Cat Canyon area of the Cat Canyon oil field : 

structure map ; columnar section 433 

East Cat Canyon area of the Cat Canyon oil field: 

columnar section 436 

East Cat Canyon area of the Cat Canyon oil field : 
map ; diagrammatic structure section ; production 

statistics 437 

Gato Ridge area of the Cat Canyon oil field : map ; 

longitudinal structure section ; well data 438 

Santa Maria Valley oil field : stratigraphic section, 441 
Santa Maria Valley oil field : structure map ; cross- 
sections 442 

Huasna area: geologic structure sections, 444 

Huasna area : geologic map 445 

Arroyo Grande (Edna) oil field: map; structure 

section 451 

Cuyama Valley, Caliente Range : columnar sections 454 
Caliente Range, Cuyama Valley, and Carrizo 

Plain : geologic map ; cross-section 455 

Bradley and San Miguel quadrangles : geologic 



map 

Type area of the Vaqueros formation : geologic map 
Type area of the Vaqueros formation: cross-section 
Type area of the Vaqueros formation : composite 

columnar section 

Soledad quadrangle : composite columnar section 

Soledad quadrangle : geologic map ; index map 

Soledad quadrangle : structure sections 

Cantua-Vallecitos area: lithologic description 

Vallecitos syncline : north-south section 

Cantua district : northeast-southwest section 

Cantua-Vallecitos district : comparative columnar 

sections 

Sargent oil field: map; cross-sections 

Moody Gulch oil field: map 

Halfmoon Bay district: map 

San Joaquin Valley : chart of geologic horizons in 

the oil and gas fields 

Coalinga Eastside oil field: correlation between 

outcrop and well sections 

Coalinga and East Coalinga Extension oil fields 
map 



457 
464 
465 



Coalinga anticline: longitudinal section 

East Coalinga Extension oil field : structure map ; 

sections 

Kettleman Hills : cross-section from Kreyenhageu 

Hills to San Joaquin Valley 

Lost Hills oil field : ideal cross-section 

Lost Hills oil field: structure map 

Devils Den district: columnar section 

Devils Den district : geologic structure sections 

Devils Den district: areal geologic map_- 

Temblor oil field : generalized graphic log ; struc- 
ture section 

MeKittrick-Cymric area of the McKittrick oil field : 

columnar section 

McKittrick Front area of the McKittrick oil field : 

structure map 

McKittrick area of the McKittrick oil field: map; 

generalized section 

Elk Hills oil field: longitudinal section 

Elk Hills oil field : structure map, eastern produc- 
ing area 

Elk Hills oil field: map 

Buena Vista Hills area of the Midway-Sunset oil 

field : generalized geologic column 

North Midway area of the Midway-Sunset oil field : 
generalized geologic sections 



465 
468 
469 
470 
472 
473 
473 

474 
476 
477 
479 

483 

484 

488 
488 

489 

491 
495 
495 
497 
49S 
49!) 

506 

508 

509 

511 
514 

514 
515 



")18 
'.19 



Figures 



Paoe 
Fig. 223. North Midway area of the Midway-Sunset oil field: Fig. 253. 

map 520 

Fig. 224. Republic area of the Midway-Sunset oil field : Fig. 254. 

geologic map; section 524 Fig. 255. 

Fig. 225. Williams and Twenty-Five Hill areas of the Mid Fig. 250. 

way-Sunset oil field: cross-section; index map 526 

Fig. 226. Williams area of the Midway-Sunset oil field : Fig. 257. 

structure map 527 Fig. 25K. 

Fig. 227. Williams area of the Midway-Sunset oil field : Fig. 250. 

columnar sections 528 Fig. 200. 

Fig. 228. Spellacy anticline, Midway-Sunset oil field : strati- 
graphic column 529 Fig. 261. 

Fig. 229. Gibson area of the Midway-Sunset oil field: coluni 

nar sections 531 Fig. 262. 

Fig. 230. Gibson area of the Midway-Sunset oil field: struc- Fig. 263. 

ture map 531 Fig. 264. 

Fig. 231. Wheeler Ridge oil field : structure map j 533 

Fig. 232. Type locality of the Tejon formation : geologic Fig. 265. 

map; index map; geologic sections 536 Fig. 266. 

Fig. 233. Type locality of the Tejon formation : stratigraphie 

section 537 Fig. 267. 

Fig. 234. Dudley Ridge gas field: map 540 

Fig. 235. Semitropic gas field: section 542 Fig. 26S. 

Fig. 236. Buttonwillow gas field: structure map 544 

Fig. 237. Ruttonwillow gas field: section 544 Fig. 269. 

Fig. 238. Canal oil field : geologic column ; structure map 547 Fig. 270. 

Fig. 239. Strand oil field: typical well log 548 

Fig. 240. Ten Section oil field: structure map; generalized Fig. 271. 

cross-section 549 

Fig. 241. Trico gas field: structure map 551 Fig. 272. 

Fig. 242. Trico gas field: stratigraphie section 552 

Fig. 243. Wasco oil field : structure map ; columnar section ; Fig. 273. 

index map 554 Fig. 274. 

Fig. 244. Rio Rravo oil field : columnar section ; structure 

map 557 Fig. 275. 

Fig. 245. Greeley oil field : stratigraphie section 560 Fig. 276. 

Fig. 246. Greeley oil field: structure map 561 

Fig. 247. Fruitvale oil field: structure map 562 Fig. 277. 

Fig. 248. Mountain View oil field : structure map 567 

Fig. 249. Kern Front area of the Kern River oil field : index Fig. 278. 

map 571 

Fig. 250. Kern Front area of the Kern River oil field: Fig. 279. 

Chanac formation. The plain and cross-hatched Fig. 280. 

areas indicate the amount of sand present in the Fig. 281. 

formation as shown in the percentage figures 572 

Fig. 251. Kern Front area of the Kern River oil field: struc- Fig. 282. 

ture map. Contours drawn on base of the Etch- 

egoin marine claystone member 572 Figs. 283 

Fig. 252. Kern Front area of the Kern River oil field : dia- 
grammatic structure section 574 



Page 
Kern River area of the Kern River oil field: dia- 
grammatic section 575 

Edison oil field : structure map 576 

Edison oil field: diagrammatic cross-section 576 

Round Mountain oil field: generalized northeast- 
southwest section 580 

Round Mountain oil field: structure map 581 

Round Mountain oil field: composite log 582 

Tracy gas field: structure map; index map 586 

McDonald Island gas field : structure map ; cross- 
section; index map 589 

Rio Vista gas field : map ; Schlumberger log ; cross- 
section of gas zone 593 

Potrero Hills gas field : columnar section 596 

Potrero Hills gas field: geologic map 597 

Fairfield Knolls gas field : map ; well log ; index 

map 600 

Rumsey Hills area: geologic map; geologic section. 602 
Rumsey Hills and vicinity : composite columnar 

sections 603 

Sites region : geologic map ; cross-section of Sites 

anticline 607 

West side of Sacramento Valley : comparative 

columnar sections of the Chico group 608 

Willows gas field : map 609 

Marysville (Sutter) Buttes gas field : geologic map ; 

geologic section 612 

Marysville (Sutter) Buttes gas field : stratigraphie 

columns of various authors 613 

Berryessa Valley : geologic sketch map ; sketch 

sections 617 

Paskenta region : geologic cross-section 619 

Paskenta region : geologic map ; cross-section of the 

Williams Butte structure 619 

Duxbury Point region : geologic map 621 

Sonoma and Marin Counties : diagrammatic colum- 
nar section 623 

Sonoma and Marin Counties : geologic map ; index 

map 624 

Sonoma and Marin Counties: geologic structure 

sections 625 

Petaluma district: geologic map 627 

Point Arena-Fort Ross region : geologic map 631 

Central Humboldt County : geologic sketch map ; 

diagrammatic section 634 

Garberville-Briceland area : geologic sketch map ; 

diagrammatic section 635 

and 284. Reproduction of "Geologic Legend" 
(Sheet IV, Geologic Map of California, 
1938) 668, 669 



INDEX MAPS TO INDIVIDUAL OIL AND GAS FIELDS 



(To accompany "Economic Mineral Map No. 2 — Oil and Gas, - ' 
N'o. Page 

101. Los Angeles City oil field. Areas: (1) Western; (2) 
Central; (3) Eastern. (On this and the following 
index maps, total productive acreage to the end of June 
1941 is shown either stippled (gas fields) or in black 
(oil fields). The "field" and "area" names used in 
connection with these maps are the ones accepted by 
the State Division of Oil and Gas. The areas indicated 
by diagonally ruled lines are the "fields" as arbitrarily 
defined by the Division of Oil and Gas ; they do not indi- 
cate possible productive acreage. Scale, 8 miles equals 
one inch.) 283 

102. Salt Lake oil field 283 

103. Beverly Hills oil field 286 

104. Whittier oil field. Areas: (1) Rideout Heights; (2) 
Whittier; (3) La Habra 291 

105. Brea-Olinda oil field. Areas: (1) Puente ; (2) Brea 
Canyon ; (3) Tonner Canyon ; (4) Olinda 291 

106. Playa del Rey oil field. Areas: (1) Ocean Front, or 
Venice; (2) Del Rey Hills 294 

107. El Segundo oil field 294 

108. Lawndale oil field 298 



in pocket, and "Citations to Selected References," in Part Three.) 
No. Page 

109. Torrance oil field. Areas: (1) Redondo ; (2) Lomita ; 

(3) Joughin 298 

110. Wilmington oil field 301 

111. Inglewood oil field 309 

112. Potrero oil field 309 

113. Rosecrans oil field. Areas: (1) Athens; (2) Central ; 

(3) Main Street; (4) South Rosecrans 324 

114. Dominguez oil field 324 

115. Long Beach oil field 324 

116. Seal Beach oil field. Areas: (1) Alamitos Heights; 

(2) Seal Beach 304 

117. Huntington Beach oil field. Areas: (1) Old Field- 

(2) Surf; (3) New Field 331 

118. Newport oil field 334 

119. Montebello oil field. Areas: (1) West Montebello ; (2) 
Montebello; (3) East Montebello 339 

120. Sante Fe Springs oil field 34(; 

121. Coyote Hills oil field. Areas: (1) West Coyote; (2) 
East Coyote; (3) Yorba Linda 354 

122. Richfield oil field. Areas: (1) Richfield; (2) Kraemer 361 

201. Capitan oil field 376 

202. Goleta oil field 379 



XVI 



Figures 



No. 
203. 
204. 
205. 
206. 
207. 

208. 

200. 



210. 



211. 



212. 



213. 
214. 

215. 



216. 

217. 
301. 
302. 
303. 
304. 



305. 
306. 
307. 
401. 
& 
402. 

403. 



Page No. 

Elwood oil field 383 404. 

La Golcla gas field 385 405. 

Mesa oil field. Areas: (1) La Mesa; (2) Palisades 385 

Summerland oil field » 386 406. 

Rincon oil field. Areas: (1) Rincon ; (2) Padre Can- 
yon; (3) San Miguelito 390 407. 

Ventura (Ventura Avenue) oil field. Areas: (1) Ven- 
tura; (2) Tip Top; (3) Black Mountain 39:; 40S. 

Ojai oil field. Areas: (1) Ojai ; (2) Sisar-SUver- 409. 

thread; (3) Sulphur Mountain; (4) Pirie ; (5) Lion 

Canyon 303 410. 

Santa Paula oil field. Areas: (1) Timber Canyon ; (2) 

Santa Paula Canyon; (3) Adams Canyon; (4) Salt 411. 

Marsh Canvon ; (5) Wheeler Canyon ; (6) Aliso Can- & 

yon 395 412. 

Sespe oil field. Areas: (1) Tar Creek; (2) Four Forks 
and Topatopa anticline ; (3) Little Sespe ; (4) Keutuck 
Wells; (5) Ivers ; (6) Devils Gate; (7) Big Sespe 

Canyon - 396 413. 

Piru oil field. Areas: (1) Hopper Canyon ; (2) Modelo ; 414. 

(3) Nigger Canyon; (4) Piru Creek; (5) Temescal ; 415. 

(6) Eureka Canyon; (7) Torrey Canyon; (8) Tapo 416. 

Canyon; (9) Holser Canyon 399 417. 

South Mountain oil field 404 

Bardsdale oil field. Areas: (1) Bardsdale ; (2) Shiells 418. 

Canyon 406 419. 

Newhall oil field. Areas: (1) Newhall-Potrero ; (2) 420. 

Pico Canyon; (3) Dewitt Canyon; (4) Towsley Can- 421. 

yon; (5) Wiley Canyon; (0) Rice Canyon; (7) Tun- 422. 

nel; (8) Elsmere ; (9) Whitney Canyon; (10) Place- 423. 

rita Canyon 411 424. 

Simi oil field. Areas: (1) Tapo Canyon; (2) Simi ; 425. 

(3) Canada de la Brea ; (4) Scarab 416 426. 

Aliso Canyon oil field 416 427. 

Lompoc oil field 429 

Casmalia oil field 429 42S. 

Santa Maria oil field 432 

Cat Canyon oil field. Areas: (1) West Cat Canyon; 429. 

(2) East Cat Canvon; (3) Los Alamos; (4) Oato 

Ridge 432 430. 

Santa Maria Valley oil field 439 

Arroyo Grande oil field 452 

Sargent oil field 476 4T , 

Coalinga oil field. Areas in Coalinga oil field proper : 
(1) Oil City; (2) East Side; (3) West Side. Areas 
in East Coalinga Extension: (4) Gatchell ; (5) 501. 

Amerada 490 502. 

Kettleman North Dome oil field 493 503. 



Page 

Kettleman Middle Dome oil field 493 

Lost Hills oil field. Areas: (1) Lost Hills; (2) 
Williamson 496 

Devils Den oil field. Areas: (1) Devils Den; (2) 
Alferitz 501 

Belridge oil field. Areas: (1) North Belridge ; (2) 

South Belridge 504 

Temblor oil field 506 

McKittrick oil field. Areas: (1) McKittrick ; (2) 
McKittrick Front; (3) Franco-Western; (4) Cymric-- 509 
Elk Hills oil field (U. S. Naval Petroleum Reserve No. 
1). Areas: (1) Elk Hills Central; (2) East Elk Hills 510 
-Midway-Sunset oil field. Areas: (1) Buena Vista Hills 
(U. S. Naval Petroleum Reserve No. 2) ; (2) North 
Midway; (3) Republic; (4) Williams; (5) Twentv- 
FiveHill; (6) Hovey Hills; (7) Lake View ; (8) Gib- 
son; (9) Signal; (10) Sunset Extension; (11) Mari- 
copa Flat 521 

Wheeler Ridge oil field 533 

Semitropic gas field 541 

Buttonwillow gas field 545 

Coles Levee oil field 545 

Paloma oil and gas field. Areas: (1) Paloma gas 

(Buena Vista Lake gas) ; (2) Paloma oil 545 

Canal oil field 547 

Ten Section oil field 550 

Strand oil field 547 

Canfield Ranch oil field 551 

Trico gas field 531 

Wasco oil field 555 

Rio Bravo oil field 558 

Greeley oil field 558 

Fruitvale oil field 564 

Mountain View oil field. Areas: (1) Mountain View; 

(2) Arvin 564 

Poso Creek oil field. Areas: (1) McVan ; (2) Agey ; 

(3) Premier 574 

Kern River oil field. Areas: (1) Kern River; (2) 

Kern Front 574 

Edison oil field. Areas: (1) Edison; (2) 21-Com- 

munity 578 

Mount Poso oil field. Areas: (1) Mount Poso; (2) 

Dorsey ; (3) Vanguard; (4) Ring; (5) Dominion 578 

Round Mountain oil field. Areas: (1) Round Moun- 
tain; (2) McDonald; (3) Coffee Canyon; (4) East- 

rnont ; (5) Oleese , 583 

Tracy gas field 590 

McDonald Island gas field 590 

Rio Vista gas field 594 



GEOLOGIC FORMATIONS AND ECONOMIC DEVELOPMENT OF THE OIL AND GAS 

FIELDS OF CALIFORNIA 



Part One 

Development of the Industry 



Editorial note: 

PART ONE represents the first of four divisions of Bulletin 118, and is intended to review the phenomenal 
growth of the oil and gas industry in California by giving incontrovertible facts and figures, presented in such a 
manner that they are readily available. Emphasis is laid on why the industry has so rapidly developed. What 
may lie in the future, however, is left to the reader's own judgment. 



The following chapters are included in PART ONE : 

Page 
CHAPTER I 



Development and Production. 



CHAPTER II 

Exploration 37 

CHAPTER III 

Early History 73 



Chapter I 

Development and Production 



CONTENTS OF CHAPTER I 

Page 
Economics of the Oil and Gas Industry of California, By J. R. Pemberton 3 

Taxation and Its Relation to Development and Production, By Granville S. Borden 15 

Historical Production Chart, By H. L. Scarborough (tip-in) 16-17 

Stocks, Shipments, and Production Charts, By H. L. Scarborough 17 

Significant Statistics, By Wm. R. Wardner, Jr 20 



Analysis of California Petroleum Reserves and Their Relation to Demand and Curtailment, By Wm. R. 

Wardner, Jr 26 



Natural Gas Fields of California, By Roy M. Bauer and John F. Dodge 33 






ECONOMICS OF THE OIL AND GAS INDUSTRY OF CALIFORNIA 



By J. R. Pembebton* 



OUTLINE OF REPORT 

Page 

Introduction 3 

Development of the industry 4 

First period — nineteenth century 4 

Second period— 1900 to 1929 4 

Third period— 1930 to 1940 5 

New methods of discovery — 1936 to 1940 6 

Geophysics 6 

The torsion balance 6 

The magnetometer 7 

The seismograph 7 

Geochemistry 7 

Results of exploration 7 

Curtailment 8 

Estimates of reserves 8 

Secondary methods of recovery 9 

Relations between landowners and operators 10 

Speculations and investments 12 

Costs of drilling and production 12 

Refining 13 

Storage and transportation 14 

Outlook for the future 14 



INTRODUCTION 

The State of California did not by chance reach the 
phenomenal development which we now find. It came 
about primarily and perhaps entirely because of the 
natural resources with which this State is blessed. 

The most important industry in California aside from 
agriculture is the petroleum industry. Modern civiliza- 
tion gives little thought to the petroleum industry's great 
responsibility of providing oil products of any desired 
specification at almost any spot in the world at a price 
satisfactory to the purchaser, but simply takes for 
granted that the oil will be provided. When it is realized 
that no wheel can turn within the State without lubri- 
cants, that nearly all transportation by modern civiliza- 
tion uses petroleum in some form or another as fuel, and 
that even our great electric plants could not operate 
without high specification mineral lubricants, then and 
then only can the importance of the petroleum industry 
be appreciated. When it is observed that to the end of 
the year 1938 the total value of the gold produced 
within the State was over $2,000,000,000 whereas the oil 
and gas that has been produced has sold for nearly 
$5,500,000,000 the particular effect of the oil and gas 
resources of the State upon its prosperity is at once 
apparent. It is comparatively a short time ago that 
Dana came around the Horn in a ship bound for Cali- 
fornia to take back a load of dried cow hides. At that 
time, that industry was the only one within the State 
engaged in any export business. When we perceive that 
in the span of our present lives, the search for, finding, 
and development of oil fields in California has resulted 
in uncovering 118 prolific oil fields and 10 gas fields, some 
of them lying at depths of 2, 2J, and nearly 3 miles below 
the surface, it is furthermore apparent that there must 
have been an enormous development of exploration 



technique, and in the actual drilling of holes and extrac- 
tion of oil and gas from the crust of the earth. This 
history, with the necessary research in geology, physics, 
chemistry, hydraulics, and applied engineering, is a 
fascinating tale, and would occupy in space many, many 
shelves in a library. In this account, we shall concern 
ourselves only with the outstanding features of the 
growth of this enormous industry within our State, its 
effect upon the economics, and the probable trend of 
development during the next 100 years. 



COMPARATIVE VALUE OF OIL, GAS, AND GOLD 
IN CALIFORNIA 



Petroleum Natural Ga$ Gold 

Value M. Cubic Feet Value Value 

$472,500 $956,102,174 

30,000 15,610,723 

29.25U 16,501.268 

30,454 18.839.141 

39.716 19,626.654 

60,828 20.030,761 

124.828 19.223,155 

257,272 17,146,416 

285.714 24,316,873 

655,000 13.600,000 

750,750 12,661,044 

870.205 14,716.506 

1.357,144 13,588.614 

1,380.666 12.000 $10,000 12,750,000 

36S.048 14,500 12.680 11,212.913 

384,200 41,250 33.000 12.309.793 

401,264 39.000 30,000 12.728,869 

561,333 75,000 55,000 12,571.900 

608.092 84,000 68,500 12,538,780 

1.064.521 85.080 79.072 13,863,282 

1.000,238 110,800 112.000 15,384.317 

1.180,793 131,100 111,457 17.181,562 

1.918,269 71.300 62,657 15,871,401 

2,376,420 111,165 74,424 15,906,478 

2,660,793 115.110 95.000 15,336,031 

4,152,928 40.566 34,578 15.863,355 

2.961.102 120,800 92,034 16,989,044 

4.692.189 120,968 99,443 16,910.320 

7.313,271 120,134 75,237 16,300.653 

8.317,809 144,437 91.035 18.633,676 

9.007.820 148.345 102.479 18.898.545 

9.238,020 168,175 109.489 18.732.452 

16. 783. 943 169,991 114,759 16,727.928 

26.566,181 842,883 474.584 18.761,559 

32.398,187 1.148.467 616.932 20.237,870 

37.680.542 10,579,933 1,676.367 19,715.440 

40.552,088 5,000,000 491.859 19,738.908 

41.868.344 12.600.000 940,076 19.713.47S 

48.578.014 14.210,836 1.053.292 20,406.958 

47.487.109 10,529,963 1.049,470 20,653.496 

13.503.837 21.992,892 1,706.480 22.442,290 

57.421.334 28.134,365 2.871.751 21,410.741 

86,976.209 44.343.020 2.964.922 20.087,504 

127,459,221 16,373,052 3.289,524 16,528,953 

142,610.563 52.173.503 4.041,217 16,695.955 

178,394.937 58,507,772 3.898,286 14,311.043 

203.138,225 67.043.797 4,704,678 15.704.S22 

173.381.265 103.628.027 6.990.030 14.670,346 

242,731,309 240.405,397 15.661,433 13.379.013 

274.652.874 209,021.596 15.153.140 13,150,175 

330. 009.829 194.719.924 15.890.082 13.065.330 

345,546,677 214.549.477 19,465,347 11.923,481 

260.735.498 224,668.940 20.447.204 11.671.018 

229.998.6S0 260,887,116 22,260.947 10.785.315 

321.360,863 400,129,201 29.067,546 8.526.703 

271.699,046 315,513.952 24.559.840 9.451,162 

141.835.723 344,959.920 16.690.695 10.814,162 

142.890.247 284.168.872 16.272.061 11.765.726 

143,063,972 271.743,544 15.403,514 15,683,075 

159,529,671 263.207.517 14.408.761 25.131.284 

179.335.311 302.447,193 17.680,661 31,165.050 

211,667.185 298.922.708 IS. 585. 970 37,710,470 

237.845,872 323,883.714 19,859,865 41.110,230 

258.354,343 332,358.439 22.310,755 45,889,515 



• Oil Umpire for California. Manuscript submitted for publica- 
tion January 5, 1940. 



Year To 


Pe 


and Incl 


Barrels 


1875 — 


175,000 


1876.. 


12,000 


1877.. 


13,000 


1878— 


15,227 


1870— 


19,858 


1880_. 


40.552 


1881— 


99.862 


1882_. 


128.636 


1883 — 


142.857 


1884.. 


262,000 


1885— 


325,000 


1886 — 


377.145 


1887. 


678,572 


1888— 


690.333 


1889— 


303,220 


1X!III__ 


307,360 


1891 — 


323,600 


1892— 


385,049 


1893 — 


470,179 


1894 — 


783,078 


1895— 


1,245,339 


1896— 


1,257,780 


1897— 


1,911,569 


1898— 


2.249,088 


]N!i!< — 


2.677.875 


1900.. 


4.329,950 


1901 — 


7.710,315 


1902. 


14,356,910 


1903— 


24,340.830 


1904 — 


29,736,003 


1905— 


34.275.701 


1906.. 


32.624,000 


1907-. 


40.311,171 


1908— 


48,306.910 


1909— 


58,191,723 


1910.. 


77.697.568 


1911 


84,648.157 


1912 


89.689.250 


1913— 


98,494.532 


1914 — 


102.881.907 


1915. 


91.146.620 


1910— 


90.262.557 


1917 


95.396.309 


1918— 


99,731.177 


linn . 


101,182,962 


1920— 


103,377,361 


1921 — 


112,599.860 


1922— 


138,468.222 


1923— 


262.875,690 


1924 — 


228,933.47) 


1925 


232.492.147 


1926— 


224.673,281 


1927 — 


231,195.774 


1928 — 


231,811.465 


1929— 


292.534,221 


1930 


227,328.988 


1931 


188.270.605 


1932— 


177,745.286 


1933 


172.139.362 


1934 _ 


174.721.282 


1935 — 


205.979.S55 


1936 


214.773.315 


1937— 


238,558.562 


1938_. 


249.395.763 


1939— 


223,725,410 



Total 5,371.838,660 $5,121,223,533 4,967,596.761 $342,540,871 $2,060,925,706 



Development and Production 



[Chap. I 
















CALIFORNIA 


L 
























CRUDE OIL PRODUCTION BY YEARS 

AND 
[TOTAL CUMULATIVE PRODUCTION 








300 
280 
260 
240 
220 
200 
H '80 

< 

m 

o- 160 
o 

tn 

| l« 

5 120 

100 
80 
60 
40 
20 















6000 

5600 

5200 

4800 

4400 

4000 

3600 £ 
< 

CD 

3200 £ 
2800 § 
2400 5 
2000 
1600 
1200 

800 

400 









































































/ 






















J 
























II 

1 I 
























1 / 


























1/ 






















/ 


V 










PRODUCTION BIT YEARS 

(SCALE AT LErT) 






/ 
























/ 


/ 
























/ 












NOTE 














/ 










I7SM0 BARBELS OP CUMULATE 
PROOULTKW PRIOR TO IB'S AND 
4>6T*S0 BARRELS PRIOR I 
TO 189* / 
































'\ 


\ 






















TOTAL CUMULATIVE PRODUCTION 

(SCAL£ AT RIGHT) 










--- 


----'' 


\ 










IBM 


■"1 



Pig. 1. 

DEVELOPMENT OF THE INDUSTRY 
FIRST PERIOD— NINETEENTH CENTURY 

Oil apparently was used by the aborigines for many 
purposes. We find that asphalt was used to mend leaks 
in boats, as an exterior coating for certain utensils to be 
ornamented by pieces of shells and colored stone stuck 
into the asphalt. Medicine men and chiefs used some of 
the natural seepages of gas to evoke fire for tribal rites. 
Apparently the white man gave scant attention to the 
oil found in many of the great seepages until the late 
sixties and early seventies, although it is quite probable 
.hat the oily asphalt may have been used for greasing 
axles of the early day wagons. Following the discovery 
by Drake in Pennsylvania that wells could be drilled 
to tap strata saturated with oil, development in Cali- 
fornia commenced, the first well to be drilled being com- 
pleted in 1865.* To the end of the nineteenth century, 



• An Economic Effect of the Rise of the American Petroleum 
Industry : Whale oil, extensively employed in the manufacture of 
soft soap, in the preparation of leather and coarse woolen cloths, 
in the making of coarse varnishes and paints, and as a machinery 
lubricant, no longer ranks as an essential. In some English towns, 
about 1819, the streets were lighted with gas made from whale 
oil. Spermaceti, a neutral, inodorous fatty substance from the 
head of the Sperm Whale, was used in the manufacture of candles, 
unguents and ointments, and as a lamp fluid. In 1859, the dis- 
covery of petroleum in America sealed the fate of whale oil as 
an illuminant, for kerosene rapidly supplanted it. In the peak 
year 1846, the American whaling fleet numbered no less than 736 
vessels with a total tonnage of 233,262 whose value exceeded $21,- 
000,000 ; the total business interests connected with the whaling 
trade were estimated at $70,000,000 with a total employment of 
70,000 persons. The financial slump of 1857 and the Civil War, 
together with the rapid growth of uses of mineral oils and the 
corresponding development of the petroleum industry all adversely 
affected whaling, which continued in a much more restricted 
fashion, the emphasis being placed on whalebone rather than 
whale oil. Perhaps the most important single factor in the decline , 
of whaling, with the attendant economic effect and decline of an 
essential section of the American merchant marine of New England, 
may be ascribed to the development of the American petroleum 
industry. Note supplied the editor by Robert F. Heizer. 



close to 3,000 wells had been drilled, less than 1,000 of 
which were on production at the end of the century. 
Cumulative total production of oil to the end of 1899 
was less than 15,000,000 bbl., slightly less than 0.3% of 
the total cumulative production at the end of 1938. 
During this period, wells were comparatively shallow, 
and confined to the proximity of surface seepages of oil. 
Some small, rather short pipe lines had been built to get 
the oil from the wells to railroads, but no trunk pipe 
lines had been built, and certainly no large refineries 
at centers of consumption had been considered. Refin- 
ing was conducted in the vicinity of the producing area. 
Twenty-two fields in all were found, of which only three 
may be classed as major discoveries — the great McKit- 
trick oil field (1898), the Kern River oil field (1899), 
and the Brea Canyon oil field (1899). Fields discovered 
prior to 1897 were all of minor importance as we know 
the industry today, and the production that year of less 
than 2,000,000 bbl. from all of the fields of the State, 
which is an amount less than 5,500 bbl. per day, obvi- 
ously did not indicate a very great demand for oil. The 
oil was used principally as fuel, although some refining 
for the manufacture of kerosene and lubricants was 
taking place. It was near the end of the century that 
oil used as fuel in locomotives began first to develop a 
demand, and in general, from this period to the present, 
development of oil fields, including their discovery, has 
been stimulated entirely by a rapidly increasing demand, 
a call for more oil, with the accompanying reward to the 
finder. 

SECOND PERIOD— 1900 TO 1929 

The petroleum industry in California reached its 
peak of development during these 30 years, and its 
growth is parallel to the development of machinery 
utilizing oil as fuel or lubricant. The automobile had 
been invented and was being manufactured and sold in 
increasing numbers. There were several makes by 1904. 
Gasoline, a product of refining, which had been the bane 
of the kerosene makers lives in the past century, now 
came into its own. Development of electricity for light- 
ing displaced kerosene in areas where electricity was 
available, and the vast multitude of new machines called 
for a rapidly increasing volume of lubricants. The large 
oil companies which we have with us today were well on 
their way at the opening of the century. 

At the end of 1904, ten more fields had been dis- 
covered, four of which were of enormous importance — - 
the East Coalinga oil field, West Coalinga oil field, Mid- 
way-Sunset oil field, and the Santa Maria (Orcutt, Lom- 
poc) oil field. During the years 1905, 1906, and 1907, 
no fields were discovered. 

With the discovery in 1904 of the Casmalia oil field, 
the thirty-second field discovered within the State, utili- 
zation of the first discovery tool was exhausted. All of 
the 32 oil fields producing prior to 1905 were discovered 
by drilling wells near surface seepages of oil or gas. 
This period of development may be likened to mining, 
and actually was conducted to a great extent by people 
who had been in the mining business. The reasoning 
was clear : if oil were coming out of the surface, and 
especially if it came out of a recognizable and easily 
traceable stratum, wells drilled to depths where that 
stratum could be encountered would produce oil. How- 



Economics op the Oil and Gas Industr y — P emberton 



ever, with the discovery of Casmalia, apparently all 
seepages within the State had been tested, and the indus- 
try was at a loss for ways and means to discover other 
oil fields obviously needed because of the rapidly increas- 
ing demand for oil and the consequent reward for dis- 
covery. 

During the late nineties and the early 1900 's, study 
and research were devoted to the problem of why oil 
should occur in certain places in prolifically productive 
pools, while elsewhere in the same strata, nothing but salt 
water was encountered. The answer to the problem was 
the anticlinal theory of the accumulation of oil. This 
theory recognized only two fundamentals. First, that 
oil, being lighter than water, would float on water. 
Assuming a mixture of oil and water in strata, the oil 
would in time segregate itself from the water and occupy 
I the higher portion of the strata, leaving the water in the 
l lower portion. Second, that the strata should not lie in 
a horizontal position. Those who had been drilling for 
oil had found that the strata containing oil and the strata 
i above the oil-bearing layer were seldom resting in a 
i horizontal position, but were tilted and sometimes folded 
into all sorts of complicated structures ; and it had been 
discovered that there were places where strata were 
actually folded into domes. The anticlinal theorists said 
that such a fold would be productive of oil because the 
oil in rising above the salt water could not get out of the 
fold and would be trapped there. Several minor require- 
ments were also suggested : ( 1 ) that the anticline or 
dome should consist of beds of rocks overlying other 
layers of rocks known to carry oil elsewhere; (2) that 
the geological section of rocks in the anticline should 
include at the base a bed of porous sandstone, to serve 
as the reservoir rock; (3) that the reservoir rock should, 
be overlain by an impermeable layer of shale or clay 
to act as a blanket, thus preventing the oil in the lower 
porous sandstone layers from rising upward to the 
ground surface. This theory was tested immediately, 
and there followed, beginning in the year 1908, a wave 
of drilling at sites selected by geologists. Oil companies 
were at first reluctant to drill upon recommendations 
made by newly graduated geologists, but noting the 
success attained by some of them, accepted the practice. 
During the 21-year period from 1908 to 1929, methods 
of applied geology resulted in the discovery of 53 oil 
fields. Furthermore, most of the greatest oil fields in 
California were tapped by the drill during this period. 

The end of this second period of development saw the 
production of 292,000,000 bbl. of oil during 1929, which 
still stands as the peak year of oil production in Cali- 
fornia. The cumulative production to the end of that 
year was 3,308,368,000 bbl. This period was character- 
ized by the development of the several great oil com- 
panies within the State; the enormous system of pipe 
lines which connects every field with trunk pipe lines 
from the San Francisco Bay region to the harbor at Los 
Angeles; and the large refineries and marine loading 
stations along the coast where oil is loaded into ships. 
There was likewise an enormous growth in the supply 
industry whereby manufacturers were pressed to design 
and construct equipment of the type needed to stand the 
increasing strains of drilling deeper into the earth's 
crust, and also to supply the enormous amounts of 
materials needed to complete the large number of oil 
wells drilled during the 21-year period. 



THIRD PERIOD— 1930 TO 1940 

The technique of finding oil and getting it out of 
the ground reached such phenomenal success in the 
years from 1923 to 1929, not only in California but all 
over the United States, that the production of oil and 
oil products exceeded the market demand. The develop- 
ment had been stimulated by greatly increased market 
demand but the reward for discovery of oil and cap- 
turing it outstripped the demand, and by the end of the 
year 1929 the surplus of oil in tanks above ground, in 
reserve in the ground, and in daily production, literally 
swamped the industry. Towards the end of 1929 ways 
and means had to be devised to curb the excess flow of 
oil, and a program of production curtailment was begun. 
Thus, prior to 1930, it may be stated that the producer 
of oil generally had no other problems than to find a 
place to drill for oil, then to get the money, and finally 
to drill the well, because a ready market was always 
available for his oil. Beginning in 1930, however, he 
was confronted with a most important problem ; that of 
finding a market. Curtailment of oil in California, 
starting in a feeble way in the last months of 1929, has 
passed through many stages, each stage being a success- 
ful improvement on the preceding one. It is now so 
thoroughly understood and accepted by all producers 
of oil as to constitute almost as fixed a necessity in busi- 
ness as taxes. Not only have the producers themselves 
been forced to curtail by failure to find markets, but 
they also have voluntarily curtailed in recognition of 
the surplus of oil. "We find that many of the oil-pro- 
ducing states have passed laws forcing producers to cur- 
tail. No law in California has successfully passed 
through the vote of the people on referendum proceed- 
ings. The Federal Government during the period Sep- 
tember, 1933, to June, 1935, had in effect a Code of 
Fair Competition for the Petroleum Industry, wherein 
regulation of production was accomplished, but on May 
28, 1935, the United States Supreme Court held the 
Code to be unconstitutional. Thus, excepting that short 
period, oil production in California has been curtailed 
entirely by voluntary agreement among the producers 
themselves since 1929. During this period of 10 years, 
the State has at all times had the ability to produce an 
amount of oil several times as great as the actual produc- 
tion. Because of this ability to produce over and above 
the expected consumptive demand for oil products, cur- 
tailment of production of all wells other than the small 
strippers will have to continue for many years to come. 
The Federal Government has taken cognizance of the 
entire subject, and from the point of view of elimination 
of waste, particularly waste of underground energy, 
has proposed from time to time to pass national legisla- 
tion for the purpose of regulating the extraction of 
petroleum from the ground. The whole subject of cur- 
tailment is complicated by the conflicting interests of 
the competitive units we find in the industry. There is 
competition between adjacent landowner lessors caused 
by their royalty interest in production ; competition 
between producers desirous of obtaining as much as 
possible from their own wells ; and competition between 
companies for all of the various and sundry reasons 
which we find in normal business activities. Curtail- 
ment is with the California oil industry to stay until 



Development and Production 



[Chap. I 



such time as the current ability of all wells within the 
State to produce oil does not exceed the current market 
demand. 

DISCOVERY OF CALIFORNIA OIL FIELDS 

Methods of Discovery 

Year Field Seepage Geology Geophysics 

1875 PICO CANYON X 

1875 EX-MISSION X 

1880 PUENTE X 

1882 TAPO EUREKA X 

1885 SISAR-SILVERTHREAD ___ X 

1886 HALF MOON BAY X 

1887 HOPPER CANYON X 

1887 SESPE X 

1887 WILEY CANYON X 

1889 ELSMERE CANYON X 

1889 NEWHALL X 

1889 RICE CANYON X 

1892 LOS ANGELES X 

1892 CONEJO X 

1894 SUMMERLAND X 

1894 BARDSDALE X 

1896 TORREY CANYON X 

1898 McKITTRICK X 

1898 WHITTIER X 

1898 MODELO X 

1899 KERN RIVER X 

1899 BREA CANYON X 

1900 EAST COALINGA X 

1900 TEMBLOR RANCH X 

1901 RIDEOUT HEIGHTS X 

1901 WEST MIDWAY X 

1901 WEST COALINGA X 

1902 SALT LAKE X 

1903 BEVERLY HILLS ._ X 

1903 LOMPOC __ X 

1903 SANTA MARIA (ORCUTT) X 

1904 CASMALIA X 

1908 CAT CANYON -. X 

1909 BUENA VISTA HILLS __ X 

1909 WEST COYOTE __ X 

1910 LOST HILLS .. X 

1910 DEVIL'S DEN __ X 

1911 EAST COYOTE __ X 

1911 SHIELL'S CANYON .. X 

1911 SOUTH BELRIDGE __ X 

1912 SIMI __ X 

1912 NORTH BELRIDGE .. X 

1914 GATO RIDGE „ X 

1916 VENTURA AVENUE __ X 

1916 SOUTH MOUNTAIN __ X 

1917 MONTEBELLO __ X 

1918 TIPTOP — FRESNO __ X 

1918 KRAEMER __ X 

1919 RICHFIELD ._ X 

1919 ELK HILLS .. X 

1920 HUNTINGTON BEACH __ X 

1921 SANTA FE SPRINGS .. X 

1921 LONG BEACH __ X 

1922 TORRANCE .. X 

1922 WHEELER RIDGE __ X 

1923 DOMINGUEZ „ X 

1923 MOUNT POSO _. X 

1924 TEMESCAL .. X 

1924 INGLEWOOD ._ X 

1924 ROSECRANS __ X 

1925 NEWPORT X 

1925 KERN FRONT ._ X 

1926 SEAL BEACH __ X 

1926 ALAMITOS HEIGHTS __ X 

1927 SULPHUR MOUNTAIN ___ __ X 

1927 RINCON __ x 

1927 COFFEE CANYON _. X 

1927 ROUND MOUNTAIN __ X 

1927 ELWOOD __ X 

1927 POTRERO .. X 

1928 HUASNA __ X 

192S LAWNDALE __ X 

1928 FRUITVALE .. X 

1928 KETTLEMAN HILLS .. X 

1928 DORSEY __ X 

1928 DOMINION __ X 

1929 PREMIER __ X 

1929 SANTA BARBARA (OLYM- 
PIC) __ X 

1929 VENICE .. X 

1929 CAPITAN __ X 

1930 TERRA BELLA .. X 

1931 CHINO __ X 

1931 SANTA BARBARA (MESA) __ X 

1931 SAN MIGUELITO __ X 

1931 PYRAMID HILLS __ X 

1932 KETTLEMAN MIDDLE 

DOME __ X 

1932 McVAN _. X 

1933 S. E. MOUNTAIN VIEW __ X 

1934 EDISON __ X 



Methods of Discovery 

Year Field Seepage Geology Geophysics 

1934 DEL REY HILLS „ X 

1934 N. W. MOUNTAIN VIEW_-_ — X 

1935 EARL FRUIT— MOUNTAIN 

VIEW _. X 

1935 LION MOUNTAIN __ X 

1935 EL SEGUNDO — X 

1935 BARTOLO (WHITTIER) .. __ X 

1936 PADRE CANYON __ X 

1936 SANTA MARIA VALLEY_. __ X 

1936 GRAPE VINE (TEJON 

RANCH) X X 

1936 WILMINGTON -- — X 

1936 TEN SECTION __ __ X 

1936 GREELEY -- — X 

1937 CANAL __ __ X 

1937 N. MOUNT POSO — X 

1937 RIO BRAVO __ .. X 

1937 ARVIN • _. __ X 

1937 YORBA LINDA __ X 

1937 NEWHALL RANCH __ -- X 

1938 CANFIELD RANCH _. __ X 

1938 PYRAMID (MOUNTAIN 

VIEW) __ X 

1938 ALISO CANYON __ X 

1938 COLES LEVEE __ __ X 

1938 TUPMAN .. __ X 

1938 COALINGA EOCENE POOL — X 

1939 STRAND __ .. X 

1939 PALOMA __ ._ X 

1939 N.E. COALINGA __ X 

1939 SOUTH MOUNTAIN VIEW. ._ X 

Totals 30 75 13 



NEW METHODS OF DISCOVERY— 1936 TO 1940 
GEOPHYSICS 

During the period from the end of 1929 to 1940, 
applied geological methods accounted for the discovery 
of 23 oil fields. In 1922, a new tool was discovered. 
This method was applied geophysics, which involved 
the use of instruments operated on the surface of the 
ground. These, because of certain reactions within 
themselves, were able to analyze subsurface rock condi- 
tions and locate favorable structures within which oil 
might be found. No instrument has so far been devised 
and universally accepted which will locate oil as such, 
although many attempts have been made and many indi- 
viduals are operating secret instruments of their own 
device with claims of success. 

The Torsion Balance 

The geophysical instruments employed success- 
fully by the industry fall into three principal classes. 
First to be used was the torsion balance. This instru- 
ment registers the force of gravity at the point upon 
which the instrument is set and locates subsurface 
masses of either lesser or greater density than the sur- 
rounding area. In the case of the salt domes in Texas 
and Louisiana, the density of the salt is much less than 
the density of the rock in which the salt has been 
intruded. Therefore, the location by the instrument of 
a mass of a lesser density than that of the surrounding 
area is assumed to indicate the presence of a salt dome. 
Drilling subsequently determines whether the dome is 
present and whether oil exists. In areas where salt 
domes do not occur, the torsion balance, by the discovery 
of subsurface masses of greater density than that of the 
surrounding area, indicates a bulging upward of deep- 
seated, heavy beds closer to the surface at the point of 
discovery than in the surrounding area, thereby indi- 
cating an anticline or dome; subsequent drilling will 
discover the characteristics of the area and whether it 
contains any oil. 



Economics of the Oil and Gas Industs y — P emberton 



The torsion balance has been unsuccessful in Cali- 
fornia principally because of the great variation in char- 
acter of sediments, the intrusive heavy volcanic rocks, 
and extremely broken up and complicated subsurface 
structure. 

The Magnetometer 

The second geophysical instrument successfully oper- 
ated was the magnetometer, an instrument that records 
the direction of the magnetic lines of force in the earth's 
crust. By mapping the pattern of these lines the sub- 
surface structure is determined. This is principally due 
to differences in electromagnetic characteristics of the 
different geological strata; and where there is a hidden 
anticline or dome, the magnetometer has been useful in 
determining this fact. 

The Seismograph 

The third instrument was the seismograph. The seis- 
mograph, using the refraction method, registers the time 
an elastic wave, caused by an explosion of dynamite, 
takes to travel from the point of explosion to a recorder. 
With the assumption that the velocity of such wave in 
any given stratum is known, after recording the time, 
the distance which the wave traveled can be calculated. 
Thus if strata lay horizontally between the point of 
explosion and the location of the instrument, a far less 
time interval would be occupied by the traveling of the 
wave than if the beds or the strata were to dip deeply 
into the earth and then return near the vicinity of the 
instrument. Later, the refraction method was discarded 
for a much better use of the seismograph by the reflec- 
tion method. In the reflection method, an elastic wave 
initiated by an explosion of dynamite rebounds from 
each stratum and comes back to the surface as an echo. 
Dynamite is exploded in the bottom of a small hole 
drilled to the water table, and recording instruments 
are placed at previously surveyed points ranging all 
the way from a few hundred yards to a mile or more 
1 away from the point of explosion, and records from the 
explosion are obtained by each recorder. The records 
I are studied and the attitude of any stratum with refer- 
: ence to a horizontal plane is determined and structure 
of that stratum is mapped. The reflection seismograph, 
because of the fact that the physical phenomena studied 
\ or recorded are man-made and therefore can be forced 
t to function at any spot desired, has so far surpassed 
i the torsion balance, magnetometer, and refraction seis- 
mograph as to cause it to be for all practical purposes 
the only successful geophysical instrument in use dur- 
ing the last few years. In California, both the torsion 
balance and magnetometer failed completely to locate 
I any oil fields, whereas 12 extremely important fields have 
been discovered by means of the reflection seismograph 
since 1936, and a very large number of these instruments 
I are now in continuous use in California. 

GEOCHEMISTRY 

It is generally assumed that more fields may yet be 
discovered by the use of the reflection seismograph, but 
with the thought that this tool involving geophysics may 
be incapable of locating all fields, a fourth method is 
just coming into use, which is called the geochemical 
method. In the use of geochemistry, which means the 



chemistry of the earth, it has been discovered that in the 
soil overlying some oil fields, through leakage of hydro- 
carbon gases during the millions of years in which the 
oil has been accumulated in the pool, slight traces of 
hydrocarbon substances may be detected. The geo- 
chemist samples the soil systematically and believes it 
possible to locate the presence of an underground oil pool 
when he obtains the necessary chemical indications in 
the soil. This method, like all the others which have 
been used, has its deficiencies, for the chemical indicators 
which are looked for in the soil may have been eroded 
away, altered, or rendered impossible of detection, or 
perhaps may never have existed. But in any case, it is 
looked on with great favor, and while as yet no oil field 
has been discovered in California by this method, fields 
impossible of location by any of the methods referred to 
previously may be discovered by this one. 

RESULTS OF EXPLORATION 

In future exploration for oil, all of the known meth- 
ods will be utilized and the search will be conducted 
only in areas known to be geologically favorable. It 
definitely may be stated that oil in commercial quanti- 
ties does not occur in areas where rocks favorable to the 
original existence of oil are not present. The favorable 
areas for exploration of oil actually comprise but a small 
part of the total area of the State. 

As a result of the application of all these methods 
for the discovery of oil, California at the beginning of 
the year 1940 has seen the development of 118 oil fields 
and 10 gas fields. In many of these fields, several sep- 
arate and distinct pools exist that really in themselves 
constitute the equivalent of other oil fields. There are 
203 entirely distinct and separate oil pools in California, 
and doubtless deeper pools yet remain to be developed 
in several of the more important oil fields where the 
drilling has as yet not penetrated the entire thickness 
of sedimentary beds known to produce oil elsewhere. 

In these oil fields there are 19,481 oil wells capable 
of production. Of these wells, 820 are not equipped with 
mechanical means of producing, having been shut in for 
curtailment purposes. Thus there are 18,661 wells 
capable of producing at a moment's notice. During the 
month of December, 1939, there were 107 new wells 
completed and thus there were 18,554 wells which were 
the effective wells actually producing as of December 1, 
1939. A table is attached showing the classification of 
these 18,554 wells on that date, according to various 
arbitrary groupings as to size. Wells in California 
range in size from those capable of producing one barrel 
daily to the great gusher wells with indeterminate capaci- 
ties that are certainly many thousands of barrels daily. 
The actual potential of large wells is never demon- 
strated because of lack of desire on the part of opera- 
tors to subject wells to the possible damage resulting in 
a wide-open flow test. From the following table, it 
may be seen that over 55% of the wells are incapable 
of producing more than 20 bbl. daily and that 75% of 
them fall below 50 bbl. daily. Likewise, 55% of the 
wells of the State are able to produce but little more 
than 3%. of the total potential of the State, while 290 
wells, representing 1.5% of the State's wells, are capable 
of producing 41.5% of the total potential of the State. 



Development and Production 



[Chap. I 



POTENTIAL GROUPING OF CALIFORNIA WELLS 
ACCORDING TO SIZE 

(All Wells in State December 1, 1939) 



Number of wells 

Accumulated 
smallest to 

Potential groups ICoch oroup largest 

0— 10 B/D (Inc.) 7.2C3 7.263 

11— 15 1.747 9,010 

16— 20 1.247 10,257 

21— 25 939 11,196 

26— 30 691 11.887 

31— 40 1,039 12.926 

41-- 50 797 13.723 

51— 75 1.166 14.889 

76— 100 712 15,601 

101— 150 758 16,359 

151— 200 458 16,817 

201— 300 443 17,200 

301— 100 210 17,470 

401— 500 144 17,614 

501— 600 84 17.698 

601 — 700 80 17.778 

701— 750 43 17,821 

751— 800 25 17,846 

801— 850 38 17.884 

851 — 900 23 17,910 

901— 950 16 17.926 

951—1000 16 17.942 

1001—1500 170 18,112 

1501—2000 152 18.264 

2001 and up 290 18,554 



Potential B/D 
Each group Accumulated 

Average smallest to 
Total per well largest 



34.061 
22.881 
22.720 
21.940 
19.634 
37,419 
36,674 
72,625 
62.964 
94.588 
81.025 
109,080 
72.849 
66.268 
46.466 
52.806 
31.927 
19,696 
31,817 
22,920 
14.880 
15,803 
211,078 
272,907 
1,048.004 



4.7 
13.1 

18.2 

23.4 

28.4 

36.0 

46.0 

62.3 

88.4 

124.8 

176.9 

246.2 

346.9 

460.2 

553.1 

660.1 

742.5 

787.8 

837.3 

881.5 

930.0 

987.7 

1,241.6 

1,795.4 

3.613.8 



34,061 

56.912 

79,662 

101,602 

121.230 

158.655 

195.329 

267.954 

330,918 

425,506 

506,531 

615,611 

688,460 

754,728 

801.194 

854,000 

885,927 

905,623 

937,440 

960,360 

975,240 

991.043 

1.202,121 

1.475,028 

2,523.032 



CURTAILMENT 

The principal object of curtailment is to preserve the 
oil of California in its natural resting place, the oil 
pool, until such time as it is needed. Obviously, the 
movement of all of the oil remaining in the ground from 
its natural reservoirs into surface tanks would be an 
inane and useless procedure, the proper course being 
to produce oil only as fast as it can be consumed; or 
in other words, as fast as the market calls for it. Oil 
can not be stored like gold, copper, iron, and other prod- 
ucts of the earth because it is highly volatile and inflam- 
mable. Thus curtailment has been devised to stabilize 
the industry and prevent waste. In California, cur- 
tailment of oil has been accomplished solely by volun- 
tary action among the producers themselves wherein a 
portion of the ability to produce of each well is assigned 
to that well as its quota of the market demand. The 
demand for products in crude oil during 1939 in Cali- 
fornia averaged 618,200 bbl. daily, or approximately one- 
quarter of the total producing capacity of the State. 
However, it would be unjust to ask a producer having 
a four-barrel well to limit his production to only one 
barrel daily and to him it would be equally unjust to 
permit a producer having a well capable of producing 
10,000 bbl. daily to produce 2,500 bbl. daily. Curtail- 
ment is similar in some respects to taxes on income. The 
larger the ability of the well to produce, the larger is its 
ability to curtail ; hence the curtailment program has 
always had as a fundamental basis the allowance first 
for a minimum allotment below which no well is asked 
to curtail. This exemption from curtailment has been 
proportionate to depth in recognition of the cumulative 
greater cost of pumping a deep well than a shallow one. 
Because of the large number of wells of great capacity 
to produce, it has been impossible to use the principle of 
applying a percentage to the remaining potential of a 
well after it has been given a minimum allotment for 
depth and a top allotment has been adopted, above which 
no well, regardless of size, shall be permitted to pro- 
duce. This top allotment has fallen from its original 
high of 450 bbl. daily to 195 bbl. daily in January, 1940. 
Thus there is an exemption granted for small wells and 



a prohibitive top placed on all large wells and the remain- 
der of the quota of the State has been obtained by apply- 
ing a power factor to the remaining potential of the 
small and intermediate wells. The outstanding fact of 
all of this is that curtailment in California is now and 
has been for some time borne principally by the large 
wells, and furthermore that the allotment to large wells 
is continually falling. This has been caused by the 
great wave of drilling for the past several years in the 
development of the many new and extremely prolific 
deep fields within the State. That the necessary burden 
of curtailment will be borne by the large wells to a 
constantly increasing amount seems likely. However, 
the law of diminishing return may function and eventu- 
ally the earnings of an expensive deep well may be so 
out of proportion to the capital cost as to cause it not 
to be drilled. 

RECORD OF OPERATIONS IN CALIFORNIA OIL FIELDS 



Wells completed 



Year 

1S75-1899_ 

1900 

1901 

1902 

1903 

1901 

1905 

1906 

1907 

190S 

1900 

1910 

1911 

1912 

1913 

1914 

1915 

1916 

1917 

1918 

1919 

1920 

1921 

1922 

1923 

1924 

1925 

1926 

1927 

1928 

1929 

1930 

1931 

1932 

1933 

1934 

1935 

1936 

1937 

1938 

1939 



New t igs 



170 

672 

766 

607 

692 

925 

1.082 

1.379 

1,327 

1.240 

1.262 

1.138 

1.160 

1.290 

1.306 

964 

259 

207 

354 

641 

1 .035 

1.094 

1.484 

1,154 

1.045 



Oil 

2.295 
808 
935 
348 
383 
328 
244 
167 
296 
594 
578 
763 
970 
776 
789 
512 
272 
613 
686 
676 
547 
572 
704 
837 
980 

1.238 
948 
913 
901 
712 
910 
755 
243 
167 
243 
451 
729 
790 

1.147 
993 
860 



2 
5 
7 
4 
8 
6 
9 
8 
8 
7 

10 
18 
10 



Dry 

629 

222 

221 

114 

134 

171 

8 

7 

11 

23 

60 

50 

104 

71 

67 

47 

20 

32 

48 

63 

51 

74 

47 

114 

347 

336 

338 

284 

281 

191 

314 

254 

238 

191 

163 

247 

347 

320 

314 

265 

96 



Weill 

Wells producing 

Total abandoned at end of year 



2.924 

1,030 

1.156 

462 

517 

499 

252 

174 

309 

622 

645 

817 

1.082 

853 

865 

567 

300 

652 

744 

757 

608 

646 

751 

951 

1.327 

1.547 

1,286 

1,197 

1,182 

903 

1,224 

1,009 

484 

375 

411 

699 

1.110 

1,122 

1,478 

1,265 

964 



Total 23,882 28,673 



6.914 35,793 



39 

252 
257 
140 
62 
75 
71 
83 
246 
402 
293 
197 
175 
214 
162 
155 
211 
159 
162 
204 
293 
587 
479 
484 
543 
512 
526 
574 
177 
172 
215 
200 
203 
208 
273 
252 



9.485 



945 

1,295 

2,152 

2.397 

2,575 

2,715 

2,734 

2.661 

2.559 

3.762 

4.282 

5,127 

5.947 

6,320 

6,817 

7,132 

7.311 

7,784 

8,362 

8.968 

9,229 

9,490 

9,980 

8,916 

9,396 

11,320 

11,069 

11,333 

11,284 

10,711 

10.515 

9,454 

8,612 

8,901 

10,158 

11,399 

12.778 

12.230 

13.463 

14.161 1 

14.844= 



1 Excludes 4.665 shut-in wells. 

2 Excludes 4.593 shut-in wells. 
* Not reported. 

ESTIMATES OF RESERVES 
In the early days of the California oil industry, no 
thought was given to the ultimate amount of oil a well 
would produce. The oil well was drilled and allowed to 
produce until it was uneconomical to operate, and the 
ultimate production was not known until then. In the 
compilation of the production records of thousands of 
oil wells very important data have been obtained which 
show that there is great variation in the amount of oil 
recovered per acre from an oil pool. This ranges from 
a few thousand barrels to more than half a million bar- 
rels per acre, and the average for the entire State is 
around 50,000 bbl. per acre. It has been found that the 
ultimate production of a well depends upon the thickness 
of the oil sand in which the oil is found ; the porosity, or 



Economics op the Oil and Gas Industr y — P emberton 



the proportion of the sand thickness that is pore space; 
the permeability, or the ease with which fluids move out 
of the pores into the hole, which is affected by the size 
of the pores and not the porosity ; the viscosity of the 
oil ; the gas-oil ratio ; the temperature and pressure ; and 
other factors of lesser importance. Suffice it to say 
that all of these factors are determinable from core sam- 
ples of the oil sand and with a portion of the productive 
life of the well as a base, it is possible to calculate within 
reasonable limits the ultimate production of an oil well. 
In addition, the ultimate production of an oil well and 
even its daily capacity to produce may be determined 
from core samples before the well is actually placed on 
production. The modern practice is to sample the sand, 
and from the study of the sample calculate the ultimate 
productivity per acre of that particular sort of sand. 
This practice is the only way of estimating the ultimate 
recovery of most of the newly discovered fields in Cali- 
fornia, of which many are exceedingly important. For 
those fields in California which have been producing oil 
for many years, in some cases as much as 50 years, it is 
customary to plot graphically the annual production of 
not only each individual well in the field but the entire 
field ; and by extending the curve expressed by the graphs 
into the future, the future production may be estimated. 
Using all methods of calculation, it has been deter- 
mined that as of January 1, 1940, the known reserve of 
oil to be produced from the known oil fields, not only 
from existing wells but from those yet to be drilled, using 
present methods of production, is approximately 3,160,- 
000,000 bbl., the State having already produced 5,391,- 
000,000 bbl. of oil. 



SECONDARY METHODS OF RECOVERY 

The reserve of 3,160,000,000 bbl. is not indicative of 
the amount of oil known to exist in the ground in Cali- 
fornia, but is the amount of oil which the existing wells, 
and those yet to be drilled in areas considered proven, 
will produce. The actual or true reserve, by which must 
be meant all of the oil to be produced in the future from 
known producing areas, is probably vastly greater ; and 
this additional oil over and above the 3,160,000,000 bbl. 
will be produced by secondary methods of recovery. 

Research by chemists and physicists on the behavior 
of oils and gases in reservoirs and the histories of the 
productive life of oil wells indicates that the conventional 
method of producing oil through an oil well is at best 
only a high grade skimming operation, and that a great 
deal of oil is left in the ground when the well ceases to 
produce. To give an example : if a container were filled 
with absolutely clean, typical oil sand, and then oil were 
poured into the container until the pores of the sand 
were saturated, it would be found impossible to extract 
from the container all of the oil which was placed there. 
The part remaining would consist of a film of oil adher- 
ing to and surrounding each grain of sand. This volume 
of oil alone may amount to as much as 20 per cent of 
the total oil placed in the container. It is estimated 
that possibly as much as 50 per cent of the original oil 
is not recovered by oil wells. 

Much study has been given to the problem of captur- 
ing this residual oil, and several so-called secondary 
methods of recovery have been devised. 




10 



Development and Production 



[Chap. I 



Secondary methods of recovering od have been tried 
successfully elsewhere and it is assumed that they may 
be utilized in California. By far the most important 
of the methods so far adopted has been the re-pressuring 
method by which gas, injected in certain wells from the 
surface back into the oil sand, passes through the sand 
and forces the residual oil to other wells. This method 
has been very successfully carried out in some of the 
fields of eastern United States where uniform sand con- 
ditions exist and the injected gas permeates the entire 
thickness of oil-bearing strata. In California, because 
of the great variation in composition of our thick sand- 
stone oil reservoirs, it has been found that injection of 
gas for re-pressuring purposes is unsuccessful because 
the gas will travel through the field in any layer of 
sand which is most permeable and thus by-pass the bulk 
of the sand containing the residual oil. The expense of 
the operation apparently so far has not been justified in 
California, and it is doubtful if in the far distant future 
this method will be used, because the gas itself may not 
be available. 

The second method of secondary recovery is the flood- 
ing process, in which water carrying soda ash or other 
alkalies in solution is injected through wells in the edge 
of the field in amounts sufficient to wash the oil in the 
sand towards the wells highest on the structure. This 
method has been used with great success in the Appa- 
lachian and Mid-Continent fields of the United States, 
but so far has never been attempted in California. It 
seems probable that this method may function with 
great efficiency in certain fields and doubtless some day 
will be tried. It is possible that the method may be 
varied by injecting chemical solvents instead of water 
at the perimeter of the oil field and by extracting the oil 
from the chemical solution as it is pumped from the wells 
high in the structure. The chemical solvent process of 
course will be expensive and until such time as oil is 
very dear it is not likely to be attempted. 

A third method of secondary recovery utilized with 
great efficiency in Germany during the world war of 
1914-1918 was the mining method, wherein shafts were 
sunk and galleries run through the field directly beneath 
the oil sand, and short wells drilled from the roof of the 
galleries upward into the sand. The oil drained through 
the wells into the galleries and was then pumped to the 
surface. In the shallow oil fields in California there 
seems to be no reason to question that this method can 
be successfully applied. 

The application of any or all of the secondary 
methods of recovery of residual oil in old oil fields will 
not occur until the search for new oil fields within the 
State meets with failure; until the production of the 
wells approaches the point where oil must be imported 
from other areas and the value or selling price of oil 
begins to increase. In other words, scarcity of oil and 
rising prices will bring about secondary methods of 
recovery. 

RELATIONS BETWEEN LANDOWNERS AND 
OPERATORS 

Assuming the operator has located a place where he 
desires to drill a well, the next step is either to purchase 
the land or, in case the purchase price of the land is 
prohibitive, to obtain a lease from the owner. A con- 



ventional lease between the landowner and the oil opera- 
tor is essentially a partnership contract in which the 
landowner permits the operator to enter upon his land 
and use as much of the surface as is necessary for the 
purpose of drilling wells for oil. The term of the lease 
is conventionally 20 years and as long thereafter as oil 
or gas is produced in commercial quantities. It is cus- 
tomary that the landowner receive a fixed sum of money 
or other consideration for signing the lease and also that 
he receive a fixed part of the proceeds of production of 
oil, gas, and casinghead gasoline. The royalty rates 
usually are one-eighth in wildcat territory and one-sixth 
in more favorable localities. Almost any lawyer is 
acquainted with the necessary details embodied in a 
lease and should be consulted before signing with an 
oil operator. The operator agrees to start drilling the 
well on some definite date, and in case he is unable to 
do so, a sum of money must be paid to extend the time 
for the commencement of drilling. In case the land- 
owner does not agree, it may be stipulated in the lease 
that drilling be commenced on a fixed date or the lease 
be terminated. 

An oil pool is a unit, and inasmuch as the days of 
intense competition between individual operators and 
landowners holding rights covering the oil pool are 
ended, and curtailment is here to stay, the operation of 
an oil pool, including its development and production 
of oil and gas, should be with proportionate profit -to 
all, and therefore for all of the best interests of the 
oil pool itself, the landowners and operators prior to the 
drilling of any wells and prior to the discovery of the 
exact producing limits of the field, often execute a unit- 
operation agreement. In unit operation, the landowners 
and operators pool their interests and each obtains his 
proportionate part of the production from the entire 
pool. In this way senseless competition between adjoin- 
ing wells is avoided ; rates of production of the pool are 
stabilized ; and the greatest return in money over the 
longest period of time results. Many unnecessary wells 
will not be drilled and more profit will result from the 
entire operation. In other words, an oil pool under a 
unit system of operation is treated as if one operator 
owned the entire pool. 

Oil, gas, and casinghead gasoline produced from 
wells are commonly sold to purchasing companies and 
the lessors' share is sold with that of the producer. 
Either the producer or the purchaser pays the lessor for 
his share. Prices paid for oil depend to a large extent 
upon the gravity of the oil and the gasoline content of 
the oil. Usually the heavier oils have less gasoline than 
do the lighter oils and hence the price paid for crude 
oil varies proportionately to the gravity. Dry gas is 
sold to public utility gas companies for an agreed price, 
there being no fixed gas market. Likewise, the market 
for casinghead gasoline fluctuates greatly and does not 
bear any constant relation to the price of crude oil, but 
usually is determined by location, proximity of market, 
and quality of gasoline. 

Excepting in a few shallow fields producing heavy 
oil, crude oil as it comes from the ground usually is 
accompanied by natural gas. The natural gas is the 
principal propulsive agency which forces the oil from 
the reservoir rock into the well and up to the surface 
of the ground. The gas as it issues from the well with 
the oil carries with it gasoline in the vapor stage and it 



Economics of the Oil and Gas Inditstr y — P emberton 



11 



is customary in an oil field which produces gas to have 
installed a casinghead gasoline plant, through which the 
gas after it is separated from the oil is passed ; and the 
gasoline, now called casinghead gasoline, is extracted, 
the dry gas going on to the public utility gas company 
pipe lines. Casinghead gasoline often produces a very 
considerable portion of the revenue derived from an oil 
well. Often the oil producer does not erect and main- 
tain his own casinghead gasoline plant and the plant is 
installed by one in that business. If this eventuality 
occurs, it is customary for the casinghead plant owner 
to execute a contract with the operator and the land- 
owner wherein the plant owner pays the operator a 
royalty portion of the gasoline manufactured and the 
landowner will therefore receive his royalty proportion 
of the oil operator's royalty. 

In the early days of production of oil in California, 
gas was considered an undesirable product. Oil wells as 
soon as completed were permitted to flow wide open into 
large open earthern pits and the gas was permitted to 
escape to the air. Because most of the oil fields were 
relatively shallow in the early days and the reservoir 
rock in which the oil occurred consisted of unconsolidated 
and loose sand, a great quantity of sand commonly came 
out of the well with the oil and gas, and the sand often 
filled the earthen pit and another had to be constructed. 
The early operator looked with pleasure upon the great 
quantity of sand his well produced because it was his 
opinion that a great cavity was being created at the 
bottom of his well, with an increasingly large surface 
of oil sand exposed and would in the end develop into a 
great underground reservoir from which he could pump 
his oil as soon as the boisterous activity of the well, 
caused by the gas present with the oil, had ended. It 
was the desire of the early operator to get as much sand 
as possible out of his well and in addition to get rid of 
the gas as quickly as possible so his well could be placed 
on the pump. The fact that wells operated in this way 
in many cases produced large quantities of salt-water 
brine with the oil at about the time the gas was exhausted 
was of no concern to the operator because it was his 
belief that the salt water was the main motivating power ; 
and the operator, finding that his well produced salt 
water, felt that it was the water that was forcing the oil 
to his well, and that it was not an undesirable factor. 

Since those days, physicists and chemists have applied 
themselves to a study of what actually goes on in the 
ground in an oil pool and have ascertained the true story 
of the behavior of oil, gas, and water in underground 
reservoirs. Results of this study indicate that gas occurs 
not only in the form of gas as gas but also exists in a 
liquefied state dissolved in the oil. In the release of 
pressure in the bottom of an oil well, because of the fact 
that the well is an open hole to the surface, the highly 
compressed and liquefied gas commences to expand 
towards the hole and forces oil ahead of each expanding 
bubble and thence up the hole. An oil field, prior to its 
being drilled, contains a fixed quantity of oil and a fixed 
quantity of gas; and the theoretically perfect way of 
producing the oil and gas from a field would be to 
produce at such rate and under such conditions as to 
cause each barrel of oil as it issues from the well to 
carry with it the exact proportion of gas which originally 
the total gas of the field bore to the total oil of the field. 



Because of the fact that gas is much more mobile than 
is liquid petroleum, gas has a tendency to force itself 
through the oil in the reservoir and issue from the well 
with the oil in increasing proportions so that unless there is 
some form of control exercised over the production of gas 
with the oil many barrels of oil remaining in the ground 
will be robbed of the gas to produce the one barrel of 
oil which issues up the hole, and all of the gas of the 
field will be produced long before all of the oil is pro- 
duced. In the operation of an oil well in such fashion 
that the original gas-oil ratio is maintained in the pro- 
duction of all of the oil from the field, the total energy 
existing in the compressed and liquefied gas is utilized. 
Because oil and gas are lighter than water, we find in 
California in all cases that the oil and gas pool is sur- 
rounded by water which saturates the same strata in 
which the oil and gas occur. The pressure in the bot- 
tom of the hole usually will vary close to 4 lb. per sq. in. 
to each 10 ft. of depth to the hole. Variations both 
under and over this pressure are caused to a great extent 
by the elevation of the well above sea level. The well 
which first taps an oil pool at a depth of 8,000 ft. 
encounters a pressure at the bottom of the hole of 
approximately 3,200 lb. per sq. in. This pressure could 
of course not exist at the bottom of the well unless a 
similar pressure existed in the water surrounding the 
oil pool. As the oil and gas are extracted from an oil 
pool, the water surrounding the pool moves up into the 
sand formerly occupied by the oil and gas because it 
has the inherent pressure to so move, but the most 
important point is that water can not encroach into the 
sand at a rate as fast as gas and light oils can leave the 
sand. Thus the pressure at the bottom of an oil well 
is seldom maintained at its original pressure during the 
life of a well but diminishes at an appreciable rate dur- 
ing the production of oil and gas from the field. This is 
not necessary, but is customarily the history of a normal 
oil and gas field, because the desire of the operators leads 
them to get the oil and gas as soon as they can rather 
than by the most efficient method. Thus unless the 
operation of an oil pool is controlled in such fashion as 
to cause the gas-oil ratio of the produced oil to be the 
same as that originally in the pool and at such rate as to 
maintain the original bottom-hole pressure, the gas-oil 
ratio decreases and finally diminishes to a negligible 
amount. The bottom-hole pressure falls to a trivial 
amount, the well will no longer flow, and pumping 
equipment must be purchased and placed in the well. 
Modern science teaches us that all of this is unnecessary 
and that all oil pools could be operated in such fashion 
that the last drop of oil in the sand would be produced 
at the surface at exactly the same pressure as is encoun- 
tered by the first well. Because the pumping of an oil 
well is expensive and especially so in deep wells, deep 
pumping wells will be abandoned by the operator while 
still capable of producing oil when the daily income is 
less than the expense. Thus large quantities of oil will 
be abandoned and never produced by these wells in such 
fields. Each year sees much progress in the method of 
handling oil and gas wells but as long as it is impossible 
to curb the competitive spirit between operators and 
landowners separated by a fence, it will be impossible to 
operate an oil field as nature intended it to be operated. 
In Texas, where an enormous surplus of producing 



12 



Development and Production 



[Chap. I 



capacity exists over and above the consumptive market 
demand, may be found the best examples of scientific 
control of production of an oil field. In California we 
have few such examples. 

SPECULATIONS AND INVESTMENTS 

Many oil wells are drilled by promoters who finance 
themselves by selling stock or interests of some sort to 
the public. It is customary for such promoters to be 
extremely optimistic in regard to the future earnings of 
their venture, and the unscrupulous promoter is prone 
to cite facts and figures about the productivity of some 
of the greatest producing fields in California and paint 
a glowing picture of the probable earnings to be gained 
from an interest in his well. Let the prospective pur- 
chaser of such interests insist not upon comparisons with 
the known great producing fields in California but upon 
actual facts as to what is known of the particular ground 
in which the prospective well is to be drilled. Usually 
other wells exist near by and some data are available. 
Let the prospective purchaser of an interest in such a 
well not concern himself with statements of the initial 
production of nearby wells, because many wells have 
been drilled in California which, while producing nearly 
a 1,000 bbl. per day during the first few days of their 
life, are perhaps producing less than 100 bbl. daily in a 
few months, and the ultimate recovery of oil from the 
well after paying the drilling costs, expenses of opera- 
tion and the royalty did not net the owners a profit, but 
actually a financial loss. There also are many wells in 
California which, although producing not more than 
400 bbl. daily during their best days have produced 
many hundreds of thousands during their lives. Thus 
initial production or rate of production is not neces- 
sarily a barometer of the total amount of oil an oil well 
will produce. Generally speaking, the prospective investor 
in an oil well may discover for himself with what regard 
the area is held by the conservative element in the oil 
industry in California by ascertaining the names of the 
oil companies which actually are operating within the 
field. Let the prospective purchaser also know how 
many acres the conservative oil companies allow for each 
well they drill, realizing that if these companies find it 
necessary to space wells such that each drains 10 acres 
of land, it must be unprofitable for those same com- 
panies to drill 10 wells on 10 acres and if the seller of 
interests in a prospective well states that he has an acre 
of land upon which to drill his well, one should divide 
by 10 the productivity and ultimate expectancies of those 
other wells drilled within the same field which are given 
10 acres of land to draw from. 

To sum up : The actual value of an oil well is 
affected by the ultimate production of oil, gas, and gaso- 
line from the well. This figure is subject to enormous 
variations in California and is affected by the acreage 
surrounding the well, the thickness of the sand, the char- 
acter of the oil, the permeability of the sand and many 
other factors. No fields within the State are so similar 
as to warrant any other than very general comparisons, 
each field and even each well being a law unto itself. 
The drilling for oil is a highly speculative business and 
not an investment business. The odds against obtaining 
oil in a wildcat well are very great. 



COSTS OF DRILLING AND PRODUCTION 

It costs money to produce oil and gas in California. 
The United States Department of the Interior in the 
year 1935, following several years study of the cost of 
producing oil, determined that the average cost in Cali- 
fornia is $0,585 per barrel of oil. This does not include 
the original cost of the land or lease upon which the 
wells are located nor the income taxes paid by the opera- 
tor upon his profits, nor the overhead and administrative 
expense, all of which would raise the cost considerably. 
When the cost of unsuccessful wildcat wells is added to 
the cost of an operator's development in the localities in 
which he got oil, the cost per barrel likewise increases 
considerably because records in California show that at 
least 37 wildcat wells are drilled before the discovery of 
an oil field, and also that a high percentage of wells 
drilled in oil fields themselves are dry holes, most of 
these being "edge" wells drilled in determining the 
extent of the field. Thus in drilling alone there are a 
great many losses which must be added to the total cost 
of being in the oil business. Again the administrative 
costs of operating an oil producing company, even 
though small, add to the total cost of producing oil. 
In going into the oil business, which one does when one 
buys stock in a new venture, it would be well to make 
some computations in which the total amount of oil 
expected to be produced is divided into all of the future 
expenses of the company to determine the actual cost of 
producing oil. This for round figures should never be 
more than 75^ per barrel in California and there are 
some leases in existence in which the operator reserves 
the right to discontinue producing oil from the land- 
owner's property if the selling price is less than 75^ per 
barrel. 



WILDCAT WELLS ABANDONED IN CALIFORNIA AND 
FIELDS DISCOVERED— 1860-1938 

Number 
wells 
Wildcat wells Fields discovered Average depth abandoned 

Year abandoned Oil Gas per well per discovery 

1860-1913 834 55 1 2.200 15 

1914 38 .. __ 2.773 

1915 11 .. __ 2.773 

1916 37 1 „ 2.773 86 

1917 44 3 — 2.773 15 

1918 44 „ __ 2.773 

1919 62 3 __ 2.773 35 

1920 125 1 .. 2.773 125 

1921 193 2 „ 2.773 97 

1922 157 1 __ 2.773 157 

1923 152 2 — 2.773 76 

1924 207 2 — 2.773 104 

\llg\ 391 2 „ 3.642 191 

1927 153 5 1 3,578 26 

1928 107 4 „ 3.733 18 

1929 209 3 2 4.134 42 

1930 169 — — 3.920 

1931 147 2 __ 4,039 158 

1932 105 __ — 3,272 

1933 87 1 __ 3.104 192 

1934- 102 2 2 3.153 26 

1935 162 1 3 3,457 41 

1936 178 4 2 3,886 30 

1937 231 3 __ 3.798 77 

1938 265 5 2 4.072 38 

1939 96 4 -- 4.890 37 

Tnt.ll 4.306 106 13 

Taxes on oil production are increasing annually. 
Apparently all governmental bodies are laboring under 
the misapprehension that an oil producer is rolling in 
profits and can be taxed accordingly. County taxes in 
most counties in California are now computed upon the 
basis of the future expected production and the pros- 



Economics of the Oil and G a s Industr y — P emberton 



13 



pective investor in an oil project may confer with the 
county assessor and determine the number of barrels per 
acre which for taxation purposes are expected to be 
produced in any portion of any oil field within a county, 
thereby obtaining a check on the promoter. Inasmuch 
as over 35,000 wells have been drilled in oil fields in 
California and in addition, over 4,200 wildcat wells have 
been drilled and abandoned, it is obvious that the dif- 
ficulty of finding new fields in California must be very 
great. With all of the scientific talent available within 
the State and with the many wildcat wells drilled each 
year, only four oil fields were discovered in the State in 
the year 1939, six being discovered in the year 1938. 
The new fields discovered are found annually at greater 
depths, and deep drilling, in addition to the exploratory 
expense in locating a place to drill, causes the cost of 
exploratory drilling to be increasing annually. The 
deepest drilling so far has been to a depth of 15,004 ft., 
although that well is producing from a depth of over 
13,000 ft. In the Rio Bravo field, all of the wells are 
over 11,000 ft. in depth and in several fields nearly all 
of the wells are over 8,000 ft. in depth ; yet 20 years ago 
there were very few wells that even had been drilled to 
a depth of 6,000 ft. 

The cost of drilling wells is approximately $10.00 
per ft. in California, after preliminary wells have deter- 
mined the most efficient way of drilling in each field. 
In the deep fields, that is those of 9,000 ft. or more, the 
cost is from $12.00 to $15.00 per ft. Some 211 wells 
in the world have already been drilled to depths greater 
than 10,000 ft. and 60 of these are in California. 

REFINING 

Those who are in the oil business are in that business 
solely because they believe that they can make more 
money in that industry than by occupying themselves 
with any other business. Oil is taken from the ground 
and converted through refining processes into all of the 
various components or products for which there is a 
demand. Thus the growth of the industry in Califor- 
nia and its development to the point we see it now is due 
entirely to an actual demand for petroleum products 
totaling 225,000,000 bbl. in the year 1939. Because 
California is not a portion of any large oil producing 
area but is isolated, our State has a rather definite and 
fixed area within which to dispose of its oil products. 
This area consists of the five western States : California, 
Oregon, Washington, Nevada, and Arizona ; and of what 
is known as the Pacific foreign market, which includes 
principally Alaska, Western Canada, Hawaiian Islands, 
Japan, Russia, China, and the Philippine Islands. To 
all of these markets petroleum products of definite and 
fixed specifications must be shipped, and each market 
has its own specifications. Gasoline of course is the 
product of most widespread, important demand and 
involves the most money. Fuel oil is second in import- 
ance, diesel oil next, and lubricants from the point of 
view of money, the item of least importance. 

In view of the fact that crude oil is worthless as such 
and only products of crude oil are demanded, the oil 
refinery, next to the oil well, is 1he most important unit 
in the oil business. Crude oil is a physical mixture of 
a great series of hydrocarbons, each of which is chemi- 
cally distinct from the other and recognized by the pro- 



portion of carbon to hydrogen in the molecule. Each 
separate hydrocarbon substance will vaporize or boil 
at a different temperature. Thus the simplest oil refin- 
ery, and the one used in the early days of the petroleum 
industry, was a simple still to which heat was applied 
and the crude petroleum boiled. At any given tempera- 
ture all of the hydrocarbons have a boiling point, equal 
to that temperature or lower, and boil off and are con- 
densed again into liquids; and with each increase in 
temperature to the still, other fractions would be vapor- 
ized and afterwards condensed. The first outstanding 
improvement over this simple topping still was the 
cracking plant. In the cracking process heavy fractions 
were subjected to a great pressure and exceedingly high 
temperatures, with the result that the molecule was torn 
apart and atoms of hydrogen and carbon re-united in 
a new combination. The result was a lighter product 
with coke as a residual by-product. By this process the 
yield of gasoline from any crude oil could be greatly 
increased over the yield from a simple topping plant. 
Beginning in 1934, research into refining methods has 
developed refining processes of breath-taking importance. 
Thus we have the method known as catalytic cracking, 
in which even larger quantities of higher quality gaso- 
line are made than under the original cracking process. 
Yields of as high as 90% gasoline have been obtained 
from charging stocks from which no gasoline could be 
obtained by any other process. Another process of 
transcendental importance is the polymerization process. 
This process is the reverse of all other refining processes 
because instead of producing lighter and more valuable 
fractions from heavier oils, gases are charged into the 
still directly and then under mild heat and pressure in 
the presence of catalysts are converted into controlled 
liquid products within the range of normal motor fuel 
gasoline. The alkylization process is an improvement on 
the polymerization process in that gases are converted into 
extremely high octane anti-knock gasolines. The hydroge- 
nation process is one in which hydrogen may be injected 
into the process of distillation and extremely valuable 
oil products of wide range are made from low-grade 
charging stocks. Many other processes of minor import- 
ance, variations of those mentioned, have been developed, 
all for the purpose of making more useful the products 
of the normal straight or topping process, and actually 
serving to make a barrel of crude oil go much farther. 
It can be stated confidently that a barrel of crude oil 
now is equivalent to perhaps four barrels of crude 30 
years ago, and annual improvements in refining tech- 
nique may be predicted to stretch the usefulness of a 
barrel of crude oil. Another extremely interesting 
development is a refining process which converts hydro- 
carbon gases into white powder which can then be con- 
verted into products from which such widely diversified 
items are made as women 's hose ; acid, heat, and cor- 
rosion resisting insulation for electric wires ; transparent 
belts, straps, and ribbons with enormous tensile strength ; 
paper of various colors which is not affected by acids, 
chemicals, or heat; and, in a word, a mass of synthetic 
products, every one of which is more durable and just 
as practical as the article imitated, the slightly increased 
price alone now preventing the widespread marketing 
of such products. In general, it may be said that the 
petroleum industry has not at any time sought to force 



14 



Development and Production 



[Chap. I 



a product into a market by endeavoring to create demand 
for something that can be made in refining processes; 
but the development of every product which is now sold, 
from medicinal oil, vaseline, insecticides, etc., down to 
coke, has been the result of a definite and fixed demand 
on the part of the public for the product. It is expected 
that the ingenuity of chemists and refiners is such that 
a great many additional petroleum products can be 
manufactured as soon as the demand exists. The avia- 
tion industry each year sees a demand for gasolines of 
higher octane rating and more power in order to drive' 
high speed aeroplane engines at high altitudes under 
conditions previously known to be formidable to the old 
type fuels. 

There are 81 refineries in California with a capacity 
of 974,000 bbl. daily. Of these, the capacity of the crack- 
ing plants alone is 114,785 bbl. daily. In addition, there 
are 109 casinghead gasoline extraction plants with an 
output capacity of 3,500,000 gal. daily. Of course nei- 
ther the refineries nor the casinghead plants operate at 
capacity, the refinery through-put being about 500,000 
bbl. dailv and the casinghead gasoline production being 
about 40',000 bbl. or 1,680,000 gal. daily. 

STORAGE AND TRANSPORTATION 

Of great importance to the petroleum industry is the 
transportation and storage system. Generally speaking, 
trunk pipe lines connect every field in the State with 
refining centers, and oil can be pumped from one end of 
the State to the other, and likewise can be delivered to 
marine loading stations along the coast at many points 
where either refined products or crude oil can then be 
transported by tankers to any part of the world. 

Oil is stored in either steel tanks or, in the case of 
extremely heavy non-gasoline bearing crude oils and 
refinery residues or fuel oils, in concrete-lined earthen 
reservoirs with wooden tops. The reservoirs range in 
size from 100,000 bbl. to 4,500,000 bbl. each, while steel 
storage ranges from small tanks up to tanks of 120,000 
bbl. capacity. The total tank capacitv for all tvpes of 
oils in California is nearly 190,000,000 bbl. In Califor- 
nia as of January 1, 1940, the total oil in storage was 
around 153,000,000 bbl. exclusive of approximately 
4,000,000 bbl. located in lease tanks adjacent to wells and 
not shipped into pipe lines. At this writing detailed 
figures are not available, but the 153,000,000 bbl. in 
storage is approximately as follows : 

Bbl. 

Gasoline Bearing Crude Oil 35,000,000 

Non-Gasoline Bearing Crude Oil 14,000,000 

Fuel Oil Residuum 69,000,000 

Coke and Distillates 8,000,000 

Finished Gasoline 14,000,000 

Natural Gasoline 2,000,000 

Gas Oil and Diesel Oil 10,000,000 

Naphtha Distillates 1,000,000 

Total 1 153,000,000 



From this it may be seen that of the 153,000,000 bbl. 
only 49,000,000 bbl. is crude, the remaining 104,000,000 
bbl. being refined products. This is because refinable 
grades of crude oil are not conveniently stored without 
excessive loss due to evaporation, and hence generally 
are put through the refinery as soon as received, and the 
products stored separately in appropriate and smaller 
sized containers. The carrying of such a large volume 
of oil in storage represents one form of frozen capital. 
Yet it would be impossible for the industry to carry on 
its normal business without adequate working stocks 
similar to those in any other business. Under present 
day conditions, wherein the movement of each grade of 
oil product is known fairly well, a convenient and work- 
able limit for storage of all products in California would 
be close to 100,000,000 bbl. of oil. Thus the above-ground 
stocks are at least 50% too great, and the industry would 
be far more comfortable were stocks to be reduced to 
around 100,000,000 bbl. Due to the large volume of 
heavy oils produced in California, the stock of California 
fuel oils above ground is commonly out of proportion to 
the movement of this commodity in trade. With over 
45% of all the above-ground stocks in California consist- 
ing of fuel oils and residuum, it can be seen that stocks 
of this one commodity are very top-heavy. Happily, 
nearly all of the recently discovered oil fields, and doubt- 
less those to be discovered, produce very light, high-grade 
refinable crudes and in time this surplus of fuel-oil stock 
will be reduced to more favorable levels. Inasmuch as 
fuel-oil stocks are carried in concrete-lined reservoirs, 
and due to the fact that evaporation is very low on this 
type of oil, the carrying charges on fuel-oil stocks are 
lower per barrel per year than for any other oil product. 

OUTLOOK FOR THE FUTURE 

Some time in the future, whether it be 20, 50, or 100 
years hence, all of the oil fields in California will have 
been located and the production of the State will be less 
than demand for the territory served. At this time 
methods of secondary recovery will have been commenced 
and enough oil imported into the State to bridge the gap. 
It is possible that the production of oil from shale like- 
wise may be attempted, there being in California large 
deposits of shale saturated with oil to the extent in some 
cases of nearly one barrel of oil to the ton of shale. Shale 
may be mined, ground, and then retorted and the vapor- 
ized oil condensed. When the secondary methods of 
recovery and the production of oil from shale decline, 
substitutes for oil will be manufactured. Substitutes 
can now be made from coal, and motor fuel can be made 
from alcohol. The success of substitutes for petroleum 
will have a profound effect upon manufacturing of 
machinery which utilizes oil or oil substitutes and even- 
tually, perhaps several generations ahead, we shall un- 
doubtedly see a complete revolution in modes of trans- 
portation and the source of power. 



TAXATION AND ITS RELATION TO DEVELOPMENT AND PRODUCTION 



By Granville S. Borden* 



The fruits of industry are divided between capital, 
labor and governments. Capital takes its redemption 
and remuneration through profits or dividends; labor 
takes its share through wages; governments take their 
share through taxes. Each must have a just share, and 
the question of what is a just share and the question of 
who shall make the allocation are vital current political 
and economic issues. Certain political philosophies con- 
tend that government should take all the fruits and that 
some dictator or politician should have irrevocable dis- 
cretion and power to distribute the fruits. Under out 
democracy we adhere to the view that capital is entitled 
to redemption and fair remuneration ; that labor shall 
have a fair wage; and that governments shall make 
equitable levies. But since all human beings are 
inherently selfish, there are many variable views in 
regard to the question of what ratios shall be applied in 
a division of the fruits and who shall have the power to 
fix these ratios. 

Perhaps all parties should devote more energy to 
means of increasing the crop, and not so much time to 
quarreling over a division of the existing crop. 

Moreover, all three parties must guard against kill- 
ing the goose that lays the golden eggs. For example, 
if the tax burden becomes oppressive and the consumer 
refuses to carry it, then business stagnates, with conse- 
quent unemployment, a reduction of profits, and cur- 
tailment of government revenue. If the producer 
assumes the increased tax burden, marginal operations 
must be closed down, and again the consequences are 
increased unemployment and diminished government 
revenue. Quite often an increase in a rate of tax results 
in a reduction of government revenue. 

Perhaps the worst detrimental feature of selfishness 
and greed on the part of any one of the three distributees 
of the fruits of industry is the retardation of expansion 
of the enterprise. Growth means new jobs, more gov- 
ernment revenue, better trade, and better standards of 
living. 

Explorations and discoveries of oil and gas fields in 
California have resulted in tremendous contributions to 
the wealth of the State and the Nation and the well 
being of its citizens. When a prospector discovers a new 
oil field, and new sources of wealth are created, new 
sources of values for taxation and new sources of income 
to be taxed are engendered ; new sources of jobs come 
into being, new stimuli to trade are quickened; new 
sources of profits are discovered. Thus there is a real 
contribution to capital, to labor, and to governments. 
There are more fruits to divide than there were before 
the discovery. There is a new supply to conserve, a dis- 
covery to offset the depletion sustained ; finally, a new 
source of revenue to aid in further exploration and dis- 
covery of new sources of wealth, to the end that there 
may be a compounding of the benefits. 

The governments' (Federal and State) share in the 
revenues of the petroleum industry in 1939 was approxi- 

•Attorney, Standard Oil Company of California. Manuscript 
submitted for publication April 15, 1940. 



mately $1,400,000,000. Part of this bill was paid by 
the consumer of gasoline and other petroleum products. 
Another part was paid by the ultimate consumer of 
other products, supplies and commodities, the cost of 
which included the tax on gasoline and other petroleum 
products. The balance of the tax was absorbed by the 
industry. 

Statistics prepared by the American Petroleum 
Industries Committee are available for interested per- 
sons to substantiate the claim that the ratio of govern- 
ments' (Federal and State) share to total revenue of 
the petroleum industry is substantially higher than the 
general average of similar ratios in other industries. 

Every member of the industry who has contributed 
services or money as a means of meeting this annual tax 
bill of $1,400,000,000 has just grounds for a feeling of 
elation and pride. Every contributor has aided in the 
accumulation of a tremendous fund of $1,400,000,000 
and in making it available for appropriations for public 
purposes. This achievement is a commendable one from 
every point of view, and a huge share of the credit 
should go to the courage and intelligence of those who 
prospected, explored, developed, and added new oil and 
gas fields to those previously known to exist. 

At the present time the following taxes are imposed 
on a California corporate operator of an oil and gas 
property : 

A. By the State of California and its political subdi- 

visions : 

1. Direct state, county and municipal taxes on real 
and personal property based on values of prop- 
erty as of the first Monday in March. 

2. Tax on the sale or use of gasoline at the rate of 
3^ per gallon. 

3. Corporation franchise tax of 4% of the net 
income derived from business done in California. 

4. Sales tax on sale of all commodities other than 
gasoline based on 3% of selling price. 

5. Use tax of 3% on cost of goods used or con- 
sumed which have not been taxed under the sales 
tax. 

6. A use fuel tax of 3^f per gallon on diesel oil and 
other fuels (other than gasoline) used. 

7. Unemployment compensation tax based on 2.7% 
of wages. 

8. Miscellaneous minor levies. 

B. By the United States : 

9. Federal income tax based on 18% of net income 
as defined. 

10. Capital stock tax based on $1 per $1,000 of the 
adjusted declared value of the capital stock. 

11. Excess profits tax based on 6% of the amount by 
which adjusted net income under the income tax 
law is in excess of 10% of the adjusted declared 
value for capital stock tax purposes, and 12% 
of the amount by which this income is in excess 
of 15% of such adjusted declared value. 



16 



Development and Production 



[Chap. I 



12. Tax on sales or use of gasoline of 1$ per gallon 
on gallons sold or used. 

13. Tax on sales of lubricating oils of 4^ per gallon. 

14. Tax on transportation of petroleum by pipe line 
equal to 4% of the service charge or a fair charge 
for similar services if not a public carrier or no 
fixed rate. 

15. Tax on tires of 2^ per pound on total weight, 
and a tax on inner tubes for tires of 4^ per pound. 

16. Tax on parts of accessories added to tank trucks, 
and tax on batteries, of 2% of sales prices. 

17. Unemployment compensation tax of 3% of wages 
paid with credit up to 90% for taxes paid under 
unemployment tax laws of a State. 

18. Old age pension tax of 1% of wages paid. 

19. Stamp taxes on stock and bond issues and trans- 
fers and also on conveyances of realty. 

In addition, as an indirect tax, there is the expense of 
keeping records; preparing returns, forms, and sched- 
ules ; and maintaining a staff of clerks, accountants, engi- 
neers, and attorneys. 

The scope of this paper does not permit a discussion 
of the problems involved, but merely a few of the impor- 
tant ones are mentioned : 

1. Problems relating to the valuations of oil and gas 
properties and leases as a basis for county assessments. 

2. Problems relating to securing proof of rights to 
statutory exemptions from taxes on sales and use of 
gasoline and other products. 



3. Problems relating to determining taxable net 
income under the California corporation franchise tax 
law and the Federal income tax law, especially problems 
relating to treatment of intangible and tangible devel- 
opment expenditures, determinations of depletion and 
depreciation, inventories, valuations in reorganizations, 
subsidiary losses, capital gains and losses, bad debts, 
interest, loss and tax deductions. 

4. Problems relating to dividends for purpose of the 
dividend paid credit against income tax rates (under the 
1936 and 1938 Revenue Acts), and the avoidance of a 
tax penalty on the accumulation of a surplus which may 
be needed in the business. (Section 102 of Internal 
Revenue Code.) 

5. Problems relating to declaration of a proper capi- 
tal stock tax value so as to minimize the capital stock 
taxes and at the same time avoid the excess profits taxes. 
(See items 10 and 11 above.) 

6. Problems relating to the determination of fair 
charges for transportation of oil by pipe line in fixing 
the base for the 4% tax on transportation of oil by pipe 
line. 

7. Problems relating to the definition of employee and 
wages under the laws imposing taxes on pay rolls. 

This list is only a broad generalization of a few of 
the important problems confronting the industry as it 
tackles the problem of making an annual self-assessment 
of some $1,400,000,000. 



17 




'S* 




1933 



iia, Nevada, 
of all prod- 
's as shown, 
auords the 

of the year 
ir the chart 
cs. For the 
iline-bearin£ 
able for the 
amelj : (1 ) 
liesel" were 
Adjustments 
i order that 



193 



HISTORICAL PRODUCTION 
CHART 

By H. L. Scarborough • 



A chronological history of the petro- 
leum industry in California from the 
beginning of the twentieth century to 
date is presented in the accompanying 
drawing. It lists the outstanding de- 
velopments in the largest industry in 
the State of California together with 
other pertinent data associated with its 
growth from infancy to its present 
gigantic proportions, wherein it sup- 
ports many allied industries and con- 
tributes millions of dollars in revenue 
to the State. The chart is intended as 
a ready reference for those within and 
without the industry. In a very con- 
venient form, it offers the discovery 
dates of the various fields and their 
consequent development ; other such 
important events as the oil workers' 
strike of 1921 and the following period 
nf intensive development which sent 
production soaring to over 850,000 bbl, 
daily ; consequent efforts at curtail- 
ment ; another period of discoveries, 
including the discovery of Kettleman 
Hills in October, 1928, with a resulting 
output of nearly 880,000 bbl. dally in 
Arjust, 1929 — the highest point of out- 
put in the history of state production. 
It shows, more recently, the organiza- 
tion of the present curtailment body. 
follo*"?d by the inauguration of the 
NIRA Petroleum Code, which became 
effective September 8, 1933, and was 
terminated on May 27, 1935 ; and more 
recently still, the strenuous curtail- 
ment efforts in the early part of 1936, 
in which the Oil Producers Agency of 
California played a prominent part. 

The compilation of the history out- 
lined hereon in conjunction with the 
actual production curve affords the 
opportunity of obtaining at a glance 
the effect of the multitude of events 
upon the production of crude petro- 
leum. It also offers a distinct picture 
"f the effort put forth by the petro- 
l'"im industry to keep the wheels of 
industry rolling with an assured sup- 
ply of the petroleum products so nec- 
to the welfare of the modern 
business world. 

Prior to 1903 production data were 
not available monthly so the daily 
average for the year is indicated. Data 
are from the Standard Oil Company of 
California ( 1900-1916 ) , Independent 
Oil Producers Agency (1917-1921), 
and from the American Petroleum In- 
stitute and the California State Oli 
Umpire (1922 to date). All of the 
data have been che- kcd by qualified 
persons in the industry, all <•( whom 
are satisfied as to their correctness. 



DIVISION OF MINES 

WALTER W BRADLEY, state mineralogist 

OLAF P. JENKINS, CHIEF GEOLOGIST 



1300 



1200 



I I 00 



1000 



< 900 

Q 



800 



700 



600 



500 



400 



300 



200 



100 



HISTORICAL CHART 

SHOWING 

CRUDE OIL PRODUCTION OF CALIFORNIA 

AND 

SIGNIFICANT HISTORICAL EVENTS 

PREPARED FOR THE 

OIL PRODUCE RS AGENCY O F CALIFORNIA 

DEC. 20, 1939 APPROVED BY TH SHERMAN 

DATA & DRAWING 1935- 1939 BY H.L.SCARBOROUGH 

APPROVED TO DECS 1, 1939 BY R.M.BLODGET 

(REDRAWN FROM ORIGINAL BY PERMISSION OF OIL PRODUCERS AGENCY) 



' Oil Producer* Agency of California. 
Manuscript (ubmltted for publication April 3, 1939. 




STATE OF CALIFORNIA 
DEPARTMENT OF NATURAL RESOURCES 



Richard sachse, oirectob 



Plate I 




16 

12. Tax 01 

on gall 

13. Tax oi 

14. Tax oi 
equal 1 
for sin 
fixed i 

15. Tax oi 
and a 1 

16. Tax oi 
and ta 

17. Unemj 
paid v 
unemj 

18. Old a£ 

19. Stamp 
fers ai 

In additio 
keeping recoi 
ules; and mai 
neers, and atl 

The scope 
of the problei 
tant ones are 

1. Probler 
properties an 

2. Problei 
statutory exe 
gasoline and 



Stocks, ShIpme n t s, 1' r oducti o n — 8 c arborougii 



17 



































STOCKS 

PACIFIC COAST TERRITORY 
..-,.... wain ffii^A^f*N 
























*0 




h^\ 


TOTAL 


5TOCKS 


















\T 




















12 




\-N 


































































































•"-. 
























/ 






i 
























J 






























/ 






— - V^> 
























/ 




























/ 






























TL 


























/ 
























, / 






if 
























\ / 






























Vy 
















































































\^ FUEL OILS-HEAV 


Y CRUDE STOC 


s 
























^ 












































































































































_T/ 






































































































































































































































»(SI 


UAL FUEL STOCKS 


































































^ 










REFINABLE C 


*UDE STOCKS 
























/N 


/\ 




*•- 
















\* 


\ 






/ 








'" ~X 




-- / 


'^""^N 


OASOUME - BEARING 








\ 






/ 
/ 












\ y 






• 








~*-\ 




/ 
















%V ^-H 






t* 




\ 




/ 

/ 




GASOLINE STOCKS 
















n 




^J 




/ 
















GASOLINE STOCKS 


^^ 










""^V— 


/ y~- 


s "v__^- 
















^~-~ = ~~^ 




• i 












ALL OTHER STOCKS 






HON - GASOLINE - BEAMING 
CfiUDE STOCKS 


"~ 




t 






















GAS 1 DIESEL OIL STOCKS 






4 
















' -"" 












„ 


















ALL OTHEH STOCKS 








1926 


1927 


1928 


1929 


1930 


1931 


1932 


1933 


1934 


1935 


1936 


193 7 


1938 





STOCKS CHART 

By H. L. Scarborough * 



Orwon / n ? P w'lKL'1 V of inventories of all petroleum products inside the Pacific Coast Territory (Arizona, California, Nevada, 
nets on hi,. tf2 ,? ^nd 'ncluding December 31, 1938 is submitted through the medium of the above chart. Storage of all prod- 
The "hitrhs' nm "W=» f£ . v, Hh from January 31, 1926, to December 31, 1938, has been plotted to give the curves as shown. 
itV.rt.nt f ? i ■ a ° f tne years de P lcted can very easily be ascertained from this record. In addition it aliords the 

student of petroleum economics a gauge of the general economic situation in the industry. 

193S E^ecUvrianrarv'To-i^the jt^^Ll^i m' U " the exception of the revisions which were made at the beginning of the year 
are taken Prior . n L H,',i ,i, d,' Bureau of Mines made several changes in its monthly report from which data for the chart 
month mentioned i?w„™ ,hf' h e Bureau h ad published consolidated figures for residual fuel oil and heavy crude stocks, 
crude „Z1' ,o> W r ' tne ,. Bu [ eau . commenced the publication of data covering three new classifications 
]e petroleum , (2) non-gasoline-bearing crude petroleum; (3) residual fuel oil. 




•Oil Producers Agency of California. Manuscript submitted for publication A| 



iril 



1939. 



18 



Development and Production 



[Chap. I 




SHIPMENTS CHART 

(January 31, 1926, to December 31, 1938) 

By H. L. Scarborough * 



utilization of ifl r Yforni* ™ ™i V, T ST l F Ty <r. a t, **?&? V n ^ e above dr awing, represent a considerable proportion of the total 

i.V- ,1 California petroleum products. During 1938. foreign and east coast markets absorbed 28.35% of the total and in 

1031 these same markets accounted for 2G.75% of the total of petroleum and its products consumed during the "ear Prior to the 
discovery and development of the Mid-Continent and Texas fields. California enjoyed considerable T the eastern demand for petroleum 
■llTo? thN bSsTness a h S a e s C i; U '.n t ', tU 'r ° f °" to h At,anti ? fore '°" destinations. Since Texas came into the picture With ^great fields aim"™ 
the Lst and ?hf «oo« hnil^f« a * can . be see n from the chart. In the last few years, however, new markets have been developed to 
the west, and the export business has shown considerable improvtment over the low levels of 1931 and 1932 

1, e ,. n'" B Li composed of three geographical divisions: Pacific Foreign, Intercoastal, and Atlantic Foreign. The first portravs 




origin J of thV iw. iY , ■ r * a ? e c " mmenein e m January, 1938. were for the reasons outlined on the stocks chart. As the 

nl rf,f™l i/Si, , k m , C .f r i«', h . f neW classln ,< : '. a t' ons "'ere not "pointed" in any of the divisions except Pacific Foreign, due 

> lack of space. Vve realize that the 193S curves are difficult to follow on this copv ; therefore, anyone desiring the data fron? which 

thej-hart was compiled for the year 193S may obtain them from the Oil Producers Agency of California Qe ' lrmg tne Qata Ir ° m Umcn 

* Oil Producers Agency of California. Manuscript submitted for publication April 3, 1939. 



Statistic s — W ardner 



19 



CALIFORNIA 1848-1938 

COMPARATIVE VALUES OF TOTAL MINERAL PRODUCTION $9,273,000,000 


















f?Jt0 9*60CO $+•> «:.* 










. 


































































4 " k °<i 


* fC -r ? *>l 






§ w .?• *•.§ i i 5s - 5 


I ^t* act! ! r '/< :::: I 2* 5 




1 J&vs5l£| \ \ * "* "a Zl ". r~" * * 3" S * j Tl ■ 


? *-*-V3 * p\ 5 ? a> > j tutu * * * "J? 5 < 

ijteSIis^-sSi^'Jll' »-S': lilt • f ;«„! > - -5: : :d l " :~|: :§:: 










' rt-r 


rr-f-m 


----i- • • • • ; ; r| 


jfrntr-r-HTl n 


■ -._^*ititm 1 1 1 1 1 m 1 1 1 1 1 1 




-—"-■-■-■"■•-'-••"-'■■ »****'•*-« f r i 5*t£E1£tri: SSU S ? J' ? § J » 

TVT*L in THOua^HD Or OOLL *»3 



Fig. 4A 



STATE DIVISION OF mine;. I94< 



TOTAL WORLD PETROLEUM 


PRODUCTION 




1900 1937 




A PERCENTAGE COMPARISON OF 


MAJOR PRODUCING COUNTRIES WITH 


PARTICULAR REFERENCE TO CALIFORNIA 


UNITED STATES 








REST OF THE WORLD 


6329% 






X 


N. 3671% 

^V^ NOTE •VC f™« S SHO*s ,.r- ....»,« 








/ ^W M TOTW. PBOOUCTiO" C7j«i«i T>< PtftlOO 








to 


/ ^tv f»9" 1900 1937 


CALIFORNIA DISTRICTS / 

-I6«»- / 






/ 




long Bcich 2iS___^^ A. 

Sinlj Ft Sprmp 1 S6 j \^ 

'• 1 *0\7- -. ^\. 


XcS 




7? 

o 




Kern Rdtf '"■>« X, / ~"~~- 

Hwi1m|loi> B««ch~ioo \^ XJ ~~— — — ^ ""--, 
Midfiji -Swmt— 83 \\/~~'"""— ~""~~"-~~- 


^f 


\^\\ v* w ^_J 


Vtnhil Am 69 \\J — ,=. ~~ '""■ 


/f/V 

Jc?/ 1 ps PRODucTioNrs 

-it lO \".i 30 BILLION BBLSJ 


1^1270 -PERSIA 


Futlrrton ■''Oxt " 


f^|265-RO UMAN|A 


Elk H.llj 52^^-V~ ~ "— """^-"^ 


\*\ \ ' 


900 — 19371 i 


3ll. Se^~T_ — ■ / 




\ Av\ 






Uonltbtllo . 38 — — T^-fc^-'S-^'''" 


/^V^v 




' "^ — ^^^ / 


lr>(lr*sod 3fl '^//\ 

•VKillrick ** / \ s^ 


X^ 


Q3l\^< 


^Vfe,^/". \\7 -BRITISH INDIA 9i 
SVN?i, oSxVSJf POLAND ?. 


LoB Hilli 28 /A ./^ 






All oIKft diSncti ./ \^^ 




I IT \ \\\^\\^«CSA''V2n>C v -Jl^ p ERu — re 

/ u lA-AVCX \\ ^SX** \^5t^-- COLOMBIA -.71 
/ »> Si 1S \'V\\<SA\V X*> a JT~-^ ARGENTINA— j7 
/ " \ \W\V\§®VVS; \ / -TRINIDAD «» 

/ > c\?\ \*\'t\ \V\\N S 

\ Z KS \ 7. \%\° n \^.\ \\\\\4lr^C^OTMER STATES-SI 








\^.\ WVjTtAVO-COLORADO OB 


NOTE Pnooucnow tci*E5 mm n 




> \ Z \ *\ \ 
CO 1 \ ^ \ \ 


\t\ \^T w VIRGINIA 13 

\ V^^WXXy-MONTANA 23 


UM#KJI<C r»l (UKI MM 3B'«i«Q 








rHOM T>|i(«[l OW *».£ »T t>< 






\^T^ \\V^MICMIGAN 3J 


CALJF. STATE OrviSO*. or MINES 






^^ \\XnEW YORK 35 

V^ KENTUCKY .51 

X-NEW MEXICO — SS 



Fig. 4B 



20 



Development and Production 



[Chap. I 



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22 



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[Chap. I 



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CO CO CO o o 


o cn ft 


cn 


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to 


to 




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t- o cn **. to 


w <o to io co 


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t~ to to 


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to 




























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ft CM CJH 


ft to CM CM 






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to i-t to CO o 


to t» to t- co to 


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CJ CO tO CO 


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CO CO c to 


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t- to ** t> en tJ" 


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to f< O IO 


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to to to "■> w 


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to t- cc o 


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24 



Development and Production 



[Chap. I 



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o 

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u 

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to 


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25 



June 1936 2,926 
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Seot. 3935 39,777 

Jan. 1937 2,657 
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Jan. 1935 9,130 
Dee. 1938 1,992 x 
Nov. 1935 23,9C9 

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26 



Development and Production 



[Chap. I 



ANALYSIS OF CALIFORNIA PETROLEUM RESERVES AND THEIR RELATION 

TO DEMAND AND CURTAILMENT 

By Wm. R. Wardner, Jr.* 



OUTLINE OF REPORT 

Page 

General statement 26 

Estimation of reserves 27 

Decline curve method 27 

Volumetric, or oil in place method 27 

Material balance method 27 

Total reserves 27 

Reserves provided by ne.w discoveries (1925-1938) 28 

Future production expectancy 29 

Demand for California petroleum products 31 

Possible future conditions 31 

Curtailment 32 

Conclusion 32 



GENERAL STATEMENT 

Curtailment of crude production in California below 
the capacity to produce will be necessary for at least 
eight more years. This conclusion is evident from a 
study of California's petroleum reserves in relation to 
the rate of withdrawal. This minimum expectation for 
continued restriction of output is based upon the assump- 
tion that no new fields will be discovered during the 
period, and is determined without giving consideration 
to probable future additions to petroleum reserves. 

A reasonable expectation with respect to future dis- 
coveries might include the bringing-in of additional 
fields and deeper pools with new reserves of one-half our 
present known reserves. Such an eventuality would 
lengthen the period during which curtailment must be 
practiced. If new reserves discovered during the period 
are as much as 1,500,000,000 bbl., curtailment of produc- 
tion will be extended over a longer period — 14 to 19 years 
— depending upon requirements. Thus the required 
extension of time for restricted production may be as 
much as 2i times the first-mentioned expectation. In this 
connection it might be pointed out that predictions have 
been circulated for many years calling attention to a 
shortage of oil just around the corner. However, today 
the State's reserves are greater than they were 15 years 
ago. 

New discoveries generally contribute a large portion 
of the reserve supply needed to insure against a future 
oil shortage. It is now apparent that more efficient 
recovery methods constantly being developed are caus- 
ing changes in estimates of recoverable oil, and promise 
to permit a substantial increase of present figures. Tech- 
nical minds in the industry envisage that any scarcity of 
crude will promote the development of improved pro- 
duction technique and that as new processes yet untried 
are brought into play, a higher percentage of recovery 
will be realized, to the extent that ultimate yield in some 
instances may be doubled. 

The study of petroleum reserves as a part of 
petroleum engineering has been carried on for many 
years, and while not an exact science insofar as accuracy 
of results is concerned, serves a very practical use in the 



•Assistant Oil Umpire for California, 
for publication February 20, 1940. 



Manuscript submitted 



industry's administration. Evaluating an oil property 
requires a study of the amount of recoverable oil, the 
expected rate of its withdrawal, and the time required 
for its production. Such an appraisal sets up values 
which may be used in establishing a price for a transfer 
of ownership, and in determining the most economic 
plan for the development and operation of a property. 
Such estimates are based on the available facts, together 
with reasonable assumptions. The assumed factors may 
include acreage, average sand thickness, average poros- 
ity, saturation, and location of edgewater. 

As the property or field under study is developed 
and establishes an historical background, more and more 
data become available. The production record and the 
data on sub-surface pressure will then indicate a trend 
of decline, permitting more exact estimates to be deter- 
mined. Revisions of former estimates then become 
necessary. As a field approaches the depleted state, 
assumptions become fewer and more of the factors 
become known, and the accuracy of appraisals is 
enhanced. Since information is now available in much 
greater detail on newly discovered fields, more accurate 
estimates of crude reserves are permitted than in the 
past. Some of the more significant studies include 
bottom-hole pressures, the analysis of core samples, meas- 
urement of the pressure, volume, temperature relation- 
ship of the oil and gas. Such studies were unknown a 
comparatively few years ago. Constant improvement in 
reserve estimates is a natural outgrowth of the studies 
of well production performance, and characteristics of 
reservoir behavior. 

Past experience shows that estimates of underground 
reserves are generally conservative. In the figures set 
forth herein, only the proven acreage has been consid- 
ered. Any statements relative to passible discoveries 
of new fields or deeper zones are mere conjecture. 
Weight has been given, however, to proven areas not 
yet developed ; in several of the newer fields where 
structural features have not been fully defined, it is 
probable that a production area larger than that used in 
this estimate will later be proven. The proportion of 
the estimated recoverable reserve to the total oil con- 
tained in the reservoir has been based on the assump- 
tion that present-day facilities and equipment will be 
used. As already stated, however, more complete recov- 
ery will undoubtedly be realized in the future through 
improved productive methods. The present expectation 
of the total ultimate recovery varies widely, and in gen- 
eral may average from 25 to 40% of the original oil in 
place. The cast of producing oil and the economic limit 
of production based on crude prices in recent years 
places a limit on the total oil recovery. As a general 
average, the limit for economic operation for shallow 
wells has been taken as 5 bbl. per day; for wells of 
medium depth, 15 bbl. per day; and for wells of 7,000 
ft. or more, 20 to 50 bbl. per day. These economic pro- 
duction limits cover lifting and operating expense only, 



Analysis of Petroleum Reserve s — W ardner 



27 



and do not include the return of invested capital. They 
vary widely depending on particular conditions. A 
higher future price, if not consumed by higher overhead 
and taxes, may reduce this economic limit and provide 
revenue for utilizing more costly methods in obtaining 
the last barrel, so to speak, or exhausting the reservoir 
within the limits of physical laws. 

ESTIMATION OF RESERVES 

Methods of estimating reserves in general use may be 
classified briefly as follows: (1) the decline curve 
method; (2) the volumetric or oil in place method; (3) 
the material balance method. 

DECLINE CURVE METHOD 

The decline curve method is best suited to the study 
of production records under constant producing condi- 
tions. Field totals or production averages of groups of 
wells may be used, or a composite curve made up from 
data of several similar wells in the same sand. The curve 
thus established is projected into the future by making 
use of the observed slope. This is most readily accomp- 
lished by plotting the data on a logarithmic graph paper 
in such a manner that they will present a straight line 
which may be projected into the future. This method is 
less accurate when curtailment is being practiced ; the 
higher the degree of curtailment, the less the value of 
the decline curve method. A thorough knowledge of the 
local conditions is necessary even where the production 
record show's a decline. The method is usually based on 
average production of groups of wells, and care must be 
taken in applying a generalized curve to a particular 
well. The greatest inaccuracies are found in the projec- 
tion at the lower and more settled rates of production. 

VOLUMETRIC, OR OIL IN PLACE METHOD 

The second method involves the calculation of the 
actual volume of oil in the reservoir. The factors used 
are: (1) thickness of the oil-bearing sand; (2) average 
percent of pore space; (3) percentage of oil saturation; 

(4) percent of connate water present in the pore space; 

(5) free gas in the sand, as well as gas held in solution 
in the oil. These factors are determined from actual 
laboratory tests of the cores. Averages for each sand 
body may be used. The acreage of the field is worked 
out from sub-surface structure data. Knowing the 
total area and the volume of oil contained per acre, the 
total quantity of oil in the reservoir may be approxi- 
mately determined. Tn these calculations, the greater 
Hie number of wells from which cores have been taken 
and analyzed, and the better their distribution through 
the productive zone and over the productive acreage, the 
greater is the accuracy of the reserve estimate. This 
total quantity of oil must then be modified by a recovery 
factor, which may be based on the measured permeability 
of the oil sands under consideration, compared to the 
same or other similar depleted oil sands where cores have 
been taken, and the oil remaining has been found by core 
analysis. Since very little information is available on 
this subject, experience and judgment generally must be 
used to supply or supplement this factor. 

MATERIAL BALANCE METHOD 

The material balance method of estimated reserves is 
based on the decline of reservoir pressure as related to 



the production of oil and gas. In general, the method 
requires a knowledge of the relationship between reser- 
voir pressure, quantities of oil and gas produced, physical 
properties of the reservoir fluids, and oil and gas con- 
tent of the reservoir. 

When a reservoir has been drilled and oil and gas are 
produced, the reservoir pressure is lowered. Because of 
the reduced pressure, the remaining oil and gas expand. 
If, at the same time, the pressure is reduced below the 
critical point, the gas vaporizes from the oil, filling the 
space vacated by the oil and gas already produced. The 
pressure decline of the reservoir is thus retarded. The 
amount which the formation pressure has declined is 
dependent upon the volume of oil and gas remaining in 
the reservoir. With the same amount of production, a 
large volume of oil and gas remaining in the reservoir 
will result in a small pressure decline, and conversely, a 
small volume of oil and gas remaining will result in a 
large pressure decline. 

The pressure-volume relationships of the oil and gas 
mixture under reservoir conditions are determined by 
testing samples in the laboratory. An assumption is 
made that complete equilibrium is attained in the reser- 
voir at all times; this condition, however, is practically 
never realized. Knowing (a) the pressure-volume rela- 
tionship of the oil and gas mixture, (b) the quantity of 
oil and gas produced, and (c) the decline of reservoir 
pressure, the total volume of the oil and gas contained 
in the reservoir can be calculated. In water-drive fields, 
the reduction in productive acreage caused by advancing 
edgewater should also be taken into account. 









TABLE 


1*** 


Indicated 








Crude 






Cumula- 


ultimate 








reserves 


Crude 


Crude 


tive total 


production 








developed 


produc- 


reserves 


produc- 


of existing 








during 


tion lor 


end ol 


tion end 


fields end 


Crude utilized 




year 


year 


year 


of year 


ol year 


Total • 


'Domestic 


1925___ 





_ 


2,889.265 










1926___ 


131,524 


224.U7 


2.796,672 


2.548.129 


5.344,801 


236,362 


143,430 


1927--_ 


159.958 


230.751 


2.725,879 


2,778.880 


5.504,759 


237,244 


156,343 


1928-__ 


1.046,919 


231,983 


3.540,815 


3,010,863 


ti.551.li7X 


232,480 


163,667 


1929_. 


229.935 


292.037 


3.478.713 


3.302,900 


6.781.613 


246.688 


175.705 


1930__. 


95.596 


228.100 


3.316.209 


3.531,000 


6.877,209 


236.442 


169,067 


1U31___ 


254,769 


188,829 


3,412.149 


3.719,829 


7.131,978 


194,057 


•154,000 


1932... 




178.128 


3.234.021 


3,897.957 


7.131,978 


179,855 


136.900 


1933 — 


158,944 


173,083 


3.219.882 


4,071,040 


7,290,922 


185,860 


137.279 


1934 — 


91.141 


175.509 


3,135,514 


4.246,549 


7.382.063 


200.778 


142.447 


1935— 


28,393 


207,832 


2,956.075 


4.454,381 


7.410,456 


202.642 


154.214 


1936___ 


358.081 


214,773 


3.099.383 


4.669,154 


7.768,537 


213.346 


166,548 


1937 — 


195.840 


238.520 


3.056,703 


4.907.674 


7.964.377 


241.706 


181.301 


1938— 


492.422 


219.125 


3.300.000 


5,156,799 


8.456,799 


223.815 


169,623 


Total 


3.243,522 


2,832,787 




•Last s 


x months average 












"Crude 


demand in 


five western 


states. Alaska and Haw 


aii 






***AH figures in thousands of barrels 











TOTAL RESERVES 

To present a picture of California reserves it is neces- 
sary to review briefly the past record. 

Figs. 5, 6, and 7 and Table I show the total reserves of 
California. A survey of individual fields has been made 
as of January 1, 1939, and from the data collected, ini- 
tial reserve or ultimate recovery, has been computed by 
adding the present reserve to the total oil produced. This 
method introduces a minimum of error, and in present- 
ing a picture of the previous years, is more accurate than 
an attempt to make use of earlier estimates. 

Fig. 5 shows the cumulative yearly production, 1918 
to 1938, inclusive. From 1922 to 1938, there has been a 
nearly constant rate of increase in cumulative produc- 
tion, with a maximum deviation in 1928 and 1929. 



28 



Development and Production 



[Chap. I 









































?> Af AA 


■■■: 


) 
































/ 






CALIFORNIA RESERVES 
AND CRUDE PRODUCTION 
















/ 










^ 


























Q 

a. 

i ) 








TO 


AL U 


TIM* 


E RE^ 


OVER 


f 


/ 

/ 






















l^"- 


o 
















_^.-^ 


^< 


/ 








UNDERGROUND 
CRUDE RESERVE 










to 

—1 
I.I 
q: 


















& 

O 












































o 
_l 








TO 


*i C 


MU * 


ivF. f 


mu 


TION 
























una 














































.,■-. 




CRUDE PRODUCED 
















«,v. 











































19*9 SK F9?l 82? 



&d 8» «2S r^7 r9?8 1929 

Fig. 5. 



Known underground reserves at the end of each year 
from 1925 to the end of 1938 are shown in the area 
between production and ultimate production curves. 
The ultimate production at the end of any year is the 
sum of production and the known reserves at that time. 

Pig. 6 shows the known underground reserves at the 
end of each year, together with the portion discovered 
during that particular year. The outstanding feature is 
the enormous increase in reserves during the year 1928 
resulting in a peak of 3,540,000,000 bbl., and the gradual 
reduction to a low of 2,956,000,000 bbl. in 1935. The 
combined discoveries of 1936, 1937, and 1938 were sub- 
stantially equal to those of 1928, and resulted in an in- 
crease to 3,300,000,000 bbl. in reserve at the end of 1938. 
It is also noteworthy that new discoveries exceeded pro- 
duction during this three-year period by 345,000,000 bbl. 

Fig. 7 shows the depletion or exhaustion of reserves 
by years since 1925. The reserves of the existing fields 
at the end of a given year have been reduced annually by 
the production of these particular fields, resulting in a 
reserve depletion curve brought down to the end of 1938. 
The total quantity of crude remaining in reserve at the 
end of each succeeding year in those same fields that 
made up the reserve of the initial year may be read from 
Fig. 7. For example, the fields making up the 1925 
reserve of 2,889,000.000 bbl. have, during the 13 years 
to the end of 1938, produced 1,839.000.000 bbl. and have 
at the end of 1938 a remainder of 1,050,000,000 bbl. in 
reserve. Likewise, the fields making up the 1928 reserves 
of 3,540,000,000 bbl. which, of course, include all fields 
discovered prior to 1928 and none afterward, had in the 
10 years up to 1938 produced 1,741.000,000 bbl. of their 
1928 reserves; at the end of 1938 the reserves remaining 
were 1,800,000,000 bbl. 

Some of the data from which these charts have been 
constructed are given in Table I, and in addition the 
total yearly crude demand (crude utilized) is shown, 
together with the annual domestic utilization. 



RESERVES PROVIDED BY NEW DISCOVERIES 
1925-1938 

A list of the fields and pools discovered each year 
since 1925 follows. These fields make up the total 
reserves developed during the year of their discovery. 
The total reserve at the end of 1938 for each field plus 
its cumulative production has been assigned to the year 
of its discovery. 

NEW DISCOVERIES 

1926 

Mount Poso (Main) 

Seal Beach ( Bixby-Selover) 

Ventura Avenue (Edison) 

1927 
Seal Beach ( Wasem ) 
Potrero 

Round Mountain 
Dominguez (3, 4, 5) 

1928 
Seal Beach (McGrath) 
Fruit vale 

Elwood (Vaqueros) 
Santa Fe (Buckbee, Nordstrom) 
Maricopa Flat 

Kettleman North Dome (Temblor) 
Lawndale 
Long Beach (Deep Zones) 

1929 
Santa Fe (Clark, O'Connell) 
Santa Barbara Mesa 
Poso Creek 
Capitan (Vaqueros) 
Playa del Rey (Venice Upper and Lower) 

1930 
West Coyote (Emery) 
North Belridge (Temblor) 

1931 
Ventura Avenue ("57") 
Gato Ridge 
Elwood (Sespe) 
San Miguelito 
Kettleman Middle Dome 
North Belridge (Wagon Wheel) 

1932 
None 

1933 
Coffee Canyon (Old) 

Mountain View (Nichols, Hood, Wharton) 
Montebello (Nutt, Cruz) 
Huntington Beach (Tideland) 

1934 
Edison 

Dominguez (Miocene) 
Inglewood (Rindge, Rubel) 
Playa del Rey (Hills) 

1935 
Coffee Canyon (New) 
Mount Poso (Baker) 
Mountain View (Earl Fruit) 
El Segundo 

1936 
Ten Section 
Greeley (Stevens) 
Wilmington (Town Lot, Terminal) 
Santa Maria Valley 
Padre Canyon 
Lost Hills (Williamson) 

1937 
Arvin 
Canal 

North Mount Poso 
Rio Bravo 
Yorba Linda 

Kettleman North Dome (Eocene) 
Montebello (West End) 
Rosecrans (Miocene) 
Newhall — Potrero 

1938 
Torrance ("34," D and B) 
Wasco 

Greeley (Vedder) 
Coalinga Nose (Eocene) 
Long Beach (Northwest Extension) 
Wilmington (Harbor) 

While there is an ever present threat that productior. 
may exceed demand, nevertheless it is necessary to carry 



Analysis of Petroleum Reserve s — \V arbseh 



29 



■ 




Uu. 






^TOTAL ^RESERVE 


iMI 




RESERVES DrSCOVERED SS 

autn* win* \ B L 


■M 
































1 ':■ 
















r^= 








L 






















fer: 




































































£ 




































































i 


m 


- 


CALIFORNIA 

UNDERGROUND RESERVE SUPPLY 

OF CRUDE PETROLEUM 

S25 »3* 


























- 










































































1 I 1 












KB 


«7 


■a 


m 




no 


1931 


1932 


S33 


S34 


■9 IS 


ssa 


1937 


S3S 


ae 



Fig. 6. 

on a constant exploratory program to develop new 
reserves and provide a backlog for future requirements. 
History shows that whenever the reserve supply seems 
to be inadequate, even though existing producing capa- 
city is far greater than market requirements, wildcat 
activity is stimulated. These eras of exploration have 
seldom failed to uncover substantial new reserves. 

In California there have been three periods of dis- 
covery. In the first period (1920 to 1924), the discovery 
of Santa Fe, Huntington Beach, and Long Beach was 
brought about largely because of increased geological 
knowledge. In the second period (1926 to 1929), dis- 
coveries of Kettleman, Elwood, Dominguez, Seal Beach, 
Santa Pe-Deep Zones, Ventura-Edison Zone, and others 
were the result of improved technique, which made drill- 
ing to greater depths possible. The third period (1930 
to 1935) was without many discoveries, because of the 
, general business depression, high inventories, low 
, demand, and lack of capital available for exploratory 
, purposes. With the use of geophysical methods, a new 
I era of discovery began in California with the discovery 
of Ten Section in the San Joaquin Valley. There fol- 
! lowed a series of important discoveries during the next 
three years, which included Rio Bravo, Greeley, Canal, 
Wilmington, and Coalinga Nose. It is likely that addi- 
tional fields will be found by this method, especially in 
the San Joaquin Valley. More obscure structural traps, 
such as overlaps, buttress sands and fault accumulations, 
which require precise and thorough geophysical surveys 
: and study, are expected to be found in the future. Since 
the past search for oil fields in California has been 
highly successful, it is reasonable to assume that new 
fields will be found by use of the new geophysical meth- 
|ods of exploration which are under development. 























1 | 








UK 




















RESERVE END OF YEAR 


















x -.. 








: -. 


-1 










IMO <n 




—J 














s^ 




^> 


^ 






X 




- 






















*^<; 


•^ 




\ 


h 










a 


PLETED 


RESERVE 


Bf YEAF 


s 


V<:_ 


LV-^ 




^„ 






■ 








*» ■ 


k ;-^-. 




/ 








*-^.* 


^-^ 








' 








-- 


■s. "•--, 


_ *"»-.__ 


J 












k ^> 


"% 




3 

3 .. 
















-^ 


:;--C 


; ^ 










"*< 




I 




CALIFORNIA 

DEPLETION OF RESERVES 

1925-1938 

IW»U OF t)f IMO ULUO) W«U * *XW U 

vm O in ntn allium * n* «*n<x nt L K 
1 tOO *l i DM wma 5 um 06 Of rlu 










— nr 


■-C^- 
























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*^>--^ 






















~~—- 


'•-'•S-^- 


r :>- 








1 1 1 
















^-: 


"^3 










«2* 


8Z? 


KB 


K 




■930 


«3i 


1932 


■933 


S3* 


-')■ 


I93A 


«37 


B3e 


ua> 



TABLE II— YEARS OF FUTURE SUPPLY AT VARIOUS 
RATES OF DISCOVERY AND VARYING DEMAND 

Total 

production Demand 

Annual rate of years before Reserve* Reserve during { n ) Reserves at end ol 

discovery shortage in as ol discovered years at end ol period 

(millions) supply ( n ) Jan. 1, 1939 in ( n ) years (demand) nth year B/D 

A — When demand in- In Thousands of Barrels 

creases at annual 
rate of lj% of 
present ( + 9,000 
B/D) 

8.2 3,300 ___ 1,850 1.450 674,000 

25 8.9 3,300 223 2,058 1,465 680,000 

50 9.7 3,300 485 2,305 1,480 687,300 

75 11.0 3,300 825 2,625 1,500 699,000 

100 12.5 3,300 1.250 3,015 1.535 712,500 

125 14.5 3.300 1,813 3,543 1,570 730,500 

150 17.0 3.300 2,550 4,230 1,620 753,000 

200 24.8 3,300 4,960 6,490 1,770 823,000 

B — When demand in- 
creases at annual 
rate of 1% of 
present (+6.000 
B/D) 

8.3 3.300 ... 1,903 1.397 649,800 

25 9.2 3,300 230 2,121 1,409 655,200 

50 103 3.300 515 2.392 1,423 661,800 

75 11.9 3.300 893 2,749 1,444 671,400 

100 13.8 3.300 1,380 3,212 1,468 682.700 

125 16.1 3.300 2,013 3,815 1,498 696.500 

150 19.3 3.300 2.895 4.656 1,539 715,80(1 

200 30.4 3.300 6.080 7.698 1,682 782,200 

C — When demand is 
constant 

9.2 3,300 __. 2,010 1,290 600.000 

25 10.6 3.300 265 2,275 1,290 600,000 

50 12.2 3.300 610 2,620 1,290 600.000 

75 14.2 3,300 1.065 3,075 1.290 600.000 

100 17.3 3,300 1,730 3,740 1,290 600,000 

125 22.0 3.300 2.750 4,760 1.290 600,000 

150 29.8 3.300 4.470 6.480 1.290 600,000 

D — When demand de- 
creases at annual 
rate of 1% of 
present (-6.000 
B/D) 

10.6 3,300 2,150 1,150 536.500 

25 11.9 3,300 298 2.458 1,140 528,500 

50 14.6 3.300 730 2,930 1,100 512,500 

75 18.3 3,300 1.373 3.618 1.055 490.000 

100 26.5 3,300 2.650 5.000 950 441,000 

K- When demand de- 
creases at annual 
rate of 11% of 
present (-9,000 
B/D) 

11.3 3.300 __. 2.228 1.072 497.500 

25 13.2 3,300 330 2,595 1.035 481,500 

50 16.8 3.300 840 3.175 965 449,000 

75 24.1 3.300 1.803 4.285 823 384,000 

FUTURE PRODUCTION EXPECTANCY 
It is the purpose to show here the reasonable future 
production expectancy under present and possible 
future conditions. Various conditions of discovery rates 
and market demand are shown together with the length 
of time which will elapse before a shortage in supply 





260 








CALIFORNIA 


o _ 

£ 


















1 


240 








Bal 


nce. Demand of Cruo 
. Petroleum 












flB 






at 


220 












BY W R WARDNER JR, 
AS OF JAN 1,1933. 








$£ 

+ 


*M 


0> 










»>a 






















, 




uS& 






2 


:BC 




















~.-fj> 


„..Y- 


£gS 












> 


160 




































tc 


140 
























„w£ 


jt 


M4J 










£ 


120 
















/ 






eg 


















o 


IOO 












7 


/ 












n nEMAHO 






J^ 


>'ji£^ 




8 


SO 












/ 








i' 


\ 1 1 1 

DECREASED DEMAND 




- 


60 




















jji 




















S 

.- 


40 








It 


































zo 












y 


/ 


























\ 











it 


// 


/ 





























Fig. 7. 



* 16 18 JO Zl 24 26 28 30 32 
YEARS BEFORE DEMANO EXCEEDS SUPPLY 

Fig. S. 



34 36 38 40 



30 



Development and Production 



[Chap. I 





CALIFORNIA 
Future Crude Reserve Discoveries Req 
The Demand For n Years At Whic 
Shortage Is Indicated. 


ireo To Supply 
h Time A 


i 

tgssoo 
















BY W R WAHDNER JR 
AS OF JAN. 1,1333. 


























































c 
o 
























/ 


/ 
















2 




fnn 


rly i 


■x'es 


Hi t 


or Decrease - 


" Demand 


/) 


















> 

J 3500 






















/ 




















tf) 






















/ 




















£ 




















/ 






r 














O 2000 










































> 
EC. 


















/ 




'$r 


tys 


















O 














f 


























a 










































o 

•- 










/ 


4 


'/ 





























20 22 M 26 28 30 32 
YEARS 



Fig. 9. 

would occur under each circumstance. No predictions 
of the future are made here. The number of years 
before market requirements will exceed production at 
varying rates of discovery and demand are, however, 
shown. There has been no attempt to project the rate 
of production to the time of complete exhaustion of the 
reserves, but only to indicate the time which will elapse 



CALIFORNIA 
RESERVES REMAINING AT THE END 
OF n f - h YEAR WHEN A SHORTAGE 
HAS BEEN REACHED. 

BY WR WARDNER JR 




before an actual shortage in supply will occur. In the 
analysis of this subject, several charts have been pre- 
pared. 

Fig. 8 shows the number of years before a shortage 
in supply would be reached under the condition of 
annual rates of discovery varying from to 250,000,000 
bbl. This relationship is shown under several condi- 
tions of demand: (1) with an annual increase of \\% 
of the present demand; (2) with an annual increase of 
1% of the present demand; (3) with a constant demand 
equal to 600,000 bbl. per day; (4) when demand 
decreases annually at the rate of 1% of the present 
demand; (5) when demand decreases annually at the 
rate of \\% of the present demand. 

Fig. 9 shows the total barrels of future crude reserves 
discoveries which would be required to supply the 
demand for n years, at which time a shortage would 
occur. In this chart, the same conditions of demand 
are shown as in Fig. 8. 

Fig. 10 shows the total reserves which will remain 
unproduced at the end of n years under the conditions of 
demand shown in Figs. 8 and 9. 



10 15 20 

n - YEARS 
Pig. 10. 



INCREASE AND DECREASE IN DEMAND AT A CONSTANT 
RATE OF CHANGE, FROM PRESENT 600,000 BBLS/DAY 



800.000 



600,000 



BY WR WARDNER JR. 
AS OF JAN. I, 1339. 



,*.* 



^ 



HP 



^ 



<F\ 



A 



it?)'' 



■«-- 



.ft*' 



oqp- 



eJSur 



CONSTANT OEMANO 




15 20 

YEARS 
Fig. 11. 



25 



30 



35 



Fig. 11 shows the demand which will exist in barrels 
per day at the end of n years. 

The data presented in these charts are also given in 
tabular form in Table II. 









Analysis op Petroleum Reserve s — W ardfer 



31 



DEMAND FOR CALIFORNIA PETROLEUM 
PRODUCTS 



The subject of demand for California petroleum is 
susceptible to considerable variation in interpretation. 
The elements of the cost of crude petroleum and the 
available supply regulate manufacturing processes ap- 
plied in refinery operations and in recovering products. 
For example, in California the gasoline demand is com- 
paratively low in relation to the available refinable crude 
production, and the greater portion of the gasoline re- 
finery through-put is straight-run gasoline. Cracking of 
the heavier crudes and fuel oils has not as yet been 
developed in California to the extent that it has in the 
Mid-Continent ; however, equipment with much addi- 
tional cracking capacity is now being installed. Along 
this line, it may be noted that the average refinery yield 
for the United States including California is 45%. The 
California average, however, is approximately 327c. It 
is quite obvious that if the total supply of crude petro- 
leum diminishes, a higher refinery yield must be realized 
in order to supply the demand for gasoline. 

The off-shore demand is subject to wide variation and 
is dependent upon world conditions and price, California 
price, and transportation costs. Practically all of the 
Atlantic seaboard demand for California petroleum 
products has been lost. Atlantic foreign demand is also 
being met by other domestic and foreign sources of sup- 
ply. This may be illustrated by the fact that for the 
four-year period 1926 to 1929 inclusive, the average 
Atlantic shipments, domestic and foreign, amounted to 
122,000 bbl. per day, whereas the average for 1935 to 
1938 inclusive was 40,000 bbl. per day This represents a 
drop of 82,000 bbl. per day. It may also be noted that 
the total California demand for crude petroleum was 
654,000 bbls. per day for the period 1926 to 1929 inclu- 
sive, while the average for the four years ending 1938 
was 600,000 bbl. per day. There has, however, been a 
substantial increase in the Pacific foreign demand, which 
has had a tendency to offset to some extent the loss in 
Atlantic business. The off-shore demand has for recent 
years approximated 25% of the total demand for Cali- 
fornia crude. Because of this off-shore outlet, it has 
been possible to hold California crude stocks at a reason- 
able level, and the petroleum industry generally has 
been able to operate at a profit and support the explora- 
tion and development programs which are so essential. 

POSSIBLE FUTURE CONDITIONS 

The present demand for petroleum products from all 
markets now being served is considered in this study as 
600,000 bbl. per day, exclusive of natural gasoline. Two 
assumptions must be made in any prediction of the 
future: (1) the actual demand which is to be expected, 
and (2) the rate of future discovery. 

It is not possible to predict the future requirements 
I from a study of the demand for the past 20 years. The 

statistics do not indicate any definite upward trend in 
', demand over a long period. It seems more likely that if 
I the available supply diminishes, improved refining 
; methods and greater utilization of crude will tend to 

reduce the total demand ; or, at least, the same volume of 
| crude will satisfy any normal increase in gasoline 
i demand. 



During the past 20 years domestic fuel oil demand 
has been considerably reduced by the increased use of 
natural gas for household and industrial fuel. Natural 
gas has largely replaced artificial sras manufactured from 
fuel oil. Whereas for the period 1921 to 1930 inclusive 
the amount of gas wasted was 39% of the total amount 
produced, during the 8-year period 1931 to 1938 inclu- 
sive this waste was reduced to less than 7% of the total 
gas produced. The conservation brought about by this 
change will be of untold benefit in increased oil recovery 
and in storing gas reserves in the natural underground 
reservoirs for future needs. It might also be noted that 
diesel fuel has been replacing fuel oil ; this process has 
not yet been concluded and a still greater use will un- 
doubtedly be made of the heavy crudes which are now 
used for fuel. 

The second assumption concerns the rate of discovery 
of crude reserves. All that can be done here is to con- 
sider a reasonable range of the annual rate of discover}. 
For the past 13 years the average discovery rate has 
been 250,000,000 bbl. per year, and the low point of 
106,000,000 bbl. per year was reached during the depres- 
sion from 1931 to 1935, when drilling and prospecting 
were at their lowest level. Thus the range for anticipated 
reserve discoveries would be between and 250,000,000 
bbl. per year; a reasonable expectation would be 100,- 
000,000 bbl. per year. Because of the constant decline 
or depletion of developed fields, and the necessity of pro- 
viding for a constant or increasing demand, new sources 
of supply continually must be discovered and drilled. 
It is estimated that the quantity of crude petroleum in 
sight for future needs as of January 1, 1939 is 3,300,- 
000,000 bbl. This is £ of the indicated ultimate produc- 
tion for California, defined as the total production to 
date plus the present known underground reserve supply. 

If the production rate in California were increased 
to the capacity of 1,400,000 bbl. per day, it is estimated 
that the decline would reduce production to the present 
demand of 600,000 bbl. per day within a period of six 
years, provided that no additional reserves were dis- 
covered. Under maximum producing conditions there is 
a wide variation in the decline rate of wells. Small 
settled producers have been observed to decline as little 
as 2% per year, and at the other extreme, new wells have 
been found that decline as much as 90% in a year's time. 
Although there is a wide difference between wells and 
fields in the State, for the purpose of this study, an 
average decline factor has been used. The rate of 
decline of the productive capacity of California oil fields 
has been computed to average 14.5% per year, taking 
wells of all classes. 

At a curtailed production rate of 600,000 bbl. per 
day, equal to present demand, the decline would be con- 
siderably reduced, thus extending the time before the 
supply was less than the demand to 9.2 years. This 
period of years, however, is calculated upon the assump- 
tion that no new fields will be discovered. Realizing that 
such a condition is quite improbable because of the recent 
widespread wildcat activity and the continued successful 
discoveries, the assumption is not considered reasonable. 
The problem becomes more involved because of the con- 
tinued discovery of new fields and the impossibility of 
predicting the frequency of discovery or the magnitude 
of the new fields. Since it is not possible to weigh the 



32 



Development and Production 



[Chap. I 



many factors affecting future production, and since the 
past cannot be regarded as a criterion, all we can hope to 
show is what the condition would be under given circum- 
stances. The rate of future discovery is one of the un- 
known factors, and for the purpose of this review, a 
range of values is taken. A relation is made showing the 
number of years which will elapse before the demand is 
exceeded by the supply, at varying annual average rates 
of discovery. Several changing rates of demand and a 
constant demand are also compared and illustrated in 
Figs. 8, 9, 10, and 11. 

The time that will elapse before the exhaustion of 
the reserves remaining unproduced at the end of n years 
is not predictable. This supply will continue over a long 
period of time because of the settled state of production 
and the low rate of decline. Reserves which are now esti- 
mated as unrecoverable, and are therefore not included 
in the present reserve estimate, may be made available 
by continued improvement in the methods of recovery. 
These methods, such as repressuring, and gas and water 
drive operations, are now being developed and should 
provide additional supply in declining years. 

CURTAILMENT 

For the past 10 years California oil fields have had 
the ability to produce under maximum conditions two 
to three times the market demand. During this time it 
has been necessary to restrict production not only to the 
demand but to an even lower level. This was for the 
purpose of reducing excessive inventories accumulated 
in 1928 to 1929 from the high flush production of Long 
Beach and Santa Fe Springs. A voluntary conservation 
program was inaugurated in November, 1929, to accom- 
plish this end. Since that time curtailment has been 
operative. The oil producers of California have curtailed 
on the average to within 5% of the quotas set for the 
State. 

The capacity of California oil fields to produce at a 
steady and sustained rate with all wells operating simul- 
taneously has been computed to be 2.3 times the present 
requirements. Production at this rate, however, if con- 
tinued for many months, would destroy the present rela- 
tive stability of the oil industry and bring about financial 
ruin and chaos generally. The development of new fields 
greatly expands the potential production of the State. 
New wells are generally large and in the initial stage are 



capable of the maximum production of their life. Under 
wide-open conditions, wells may produce from 30% to 
90% of their ultimate production during the first year. 
Under curtailment, however, these large flush new wells, 
which in some cases have potentials as high as 5,000 bbl. 
per day, are pinched back to as little as 200 bbl. per day, 
which represents only a small part of their capacity. In 
this manner the natural flowing life of a large number 
of wells will be extended for many years after the time 
they would otherwise have ceased to flow, and would 
have been put on the pump. As wells are produced nor- 
mally, the rate of production is constantly declining; and 
likewise if they are curtailed their potential will still 
decline, although the actual restricted production may 
be more or less constant. 

CONCLUSION 

In conclusion it might be pointed out that the study 
of reserves is not an exact science and in the calculation 
of reserves many variable factors are taken into account. 
Therefore, a constant revision of estimates is necessary. 
Present California crude reserves are adequate to provide 
for requirements for at least 10 years. Improved pro- 
duction methods and a continuation of discoveries, at a 
normal rate, will provide for the bulk of California's 
future demand 20 to 25 years hence, although existing 
wells will still be producing substantial quantities at 
that time. More specifically, the discovery of 1,500,000,- 
000 bbl. of new reserves during the entire period will 
necessitate a restricted output for 14 to 19 years. 

In present fields, increased recovery resulting from 
improved production practices can be anticipated as a 
source of additional supply. The likelihood of discover- 
ing substantial additional reserves is enhanced by the 
new scientific methods of exploration. The vast acreage 
of the San Joaquin Valley and the Coastal Plains offers 
fertile ground for the application of these methods. Cur- 
tailment of output should be energetically promoted and 
adhered to if economic stability in the industry is to be 
maintained. The assurance of stable conditions is essen- 
tial to provide for a vigorous exploration and develop- 
ment program necessary to insure a continuous future 
supply for the industry. 

Bibliography: Hoots, H. W. 39a; Hubbard, W. E. 37; Katz, 
D. L. 36 ; Minshatl, F. E. 37 ; Pyle, H C. 39 ; Schilthuis, R. J. 36 ; 
Sherborne, J. E. 39 ; Wilhelm, V. H. 39a. 



NATURAL GAS FIELDS OF CALIFORNIA* 

By Roy M. Bauer** and John F. Douge*** 



OUTLINE OF REPORT 

Page 

Modes of occurrence 33 

Early history 33 

Developments in the past decade 35 

Further dry gas discoveries 35 

Recent deep fields in San Joaquin Valley 35 

Development of utilization 35 

Significance of the industry 35 

Relationship between gas and oil production 36 

Importance of dry gas fields 36 

Position of gas in stratigraphic column 36 



MODES OF OCCURRENCE 

Natural gas occurs in two ways: (1) as a separate 
and distinct product, not associated with petroleum 
deposits; this is called dry gas, or marsh gas; (2) in oil 
sands and associated with petroleum ; in this case the 
gas is produced with the oil, and separated mechanically 
from it at the surface or casing head of the well, and is 
known as casinghead gas. 

EARLY HISTORY 

California's first natural gas production, a dry gas 
or marsh gas, was developed from an artesian well 
drilled at Stockton in 1864. A number of additional 
wells were drilled over a period of years, not only at 
Stockton, but also at Sacramento. All of the wells were 
small producers, yielding from 5,000 to 120,000 cu. ft. of 
gas per day. The heating value was rather low — 650 to 
800 B.t.u. per ft. as compared with the 1,000 to 1,150 
B.t.u. per ft. for the average casinghead gas. The pro- 
duction was never sufficient for the needs of the com- 
munity. At the present time, no gas is being produced 
commercially from these wells. 

The first productive oil and gas well was completed 
in Pico Canyon near Newhall in Los Angeles County in 
1870. Large oil production was developed in the San 
Joaquin Valley in the Coalinga, McKittrick, and Kern 
River fields at the turn of the century, but it was not 
until 1909, when the large-volume high-pressure gas 
wells were drilled in the Buena Vista Hills, Kern 
'County, that attention was focused on natural gas 
obtained from oil fields. Because of the absence of 
proper high-pressure separators or gas traps and the 
inability to handle the high-pressure wells with the 
;equipment then available, great wastage of dry gas from 
the upper sands, as well as casinghead gas, prevailed 
for a number of years. Since 1909, however, the" pro- 
portion of gas utilized has gradually changed, from 
almost complete wastage to practically complete utiliza- 
tion. (See Tables I and II.) 



* Manuscript submitted for publication March 13, 1940. 

** Gas Supply Supervisor, Southern California Gas Company 
and Southern Counties Gas Company, Los Angreles, Cali- 
fornia. 

*•• Professor of Petroleum Engineering, University of Southern 
California, Los Angeles, California. 



TABLE I— CALIFORNIA: DRY GAS PRODUCTION 

(Cumulative to January 1, 1940) 

M. cu. It. 

Buena Vista Hills 107,487,732 

Buttonwillow 16,741,600 

Dudley Ridge 2,053,500 

Elk Hills 75,912,805 

Fairfield Knolls 14,333 

La Goleta 14,886,887 

Long Beach 1,475,876 

Marysville Buttes 1,332,349 

McDonald Island 18,004,747 

McKittrick 1,032,953 

North Midway 1,826,381 

Paloma (formerly Buena Vista Lake) 2,589,418 

Potrero Hills 

Rio Vista 11,899,908 

Rosecrans 29,453 

Santa Fe Springs 7.919J99 

Seal Beach 610,334 

Semitropic 2,818,434 

Tracy 8,068,238 

Trico 4,184,624 

Grand total 278,889,371 

The total dry gas production of California represents only 3.9% 
of the total natural gas produced in the State. 

TABLE II— CALIFORNIA: NATURAL GAS PRODUCTION 
AND UTILIZATION 

Vnconserved gas 

M. en. It. net production from formation Total p fr 

Year Casinuhead Dry Total rtilization M. cu. ft. cent 

Prior.. 65.314,000 65.314,000 457,200 64.856.800 99.3 

1906— 20,465,000 20,465,000 153,000 20,312,000 99.2 

1907. _ 28,570,000 28,570,000 230,000 28.340,000 99.2 

1008— 33,920,000 33,920,000 479,000 33,441,000 98.6 

1909__ 39,290,000 1,305.000 40,595,000 2.324,000 38,271.000 94.3 

1910— 57,094,000 7,866,200 64.960.200 2,764,000 62,196,200 95.7 

1911__ 66,475,000 7,017.389 73.492,389 6.390,000 67.102.389 91 3 

1912 — 70.989,000 5.387,581 76,376,581 9,355,000 67,021.581 87.8 

1913 — 80.271,000 6,541,485 86,812,485 11,035,000 75.777,485 87.3 

1914— 89,435.000 7.011,996 96.446,990 17,829.000 78.617,996 81.5 
1P15._ 74,475,000 4,487,847 78.962,847 21.891.000 57,071.847 72.3 
1916.. 74,819,000 5,286.684 80,105,684 31,643,000 48.462,684 60.5 
1917— 82,740,000 10,589,401 93,329.401 49,427,000 43,902.401 47.0 
1918__ 91,225.000 11,453.908 102,678,908 39,719.000 62,959,908 61.3 
1919— 89.970,000 26,326.233 116,296,253 55,607,000 60,689,253 52.2 
1920__ 95,948.000 22,743,444 118,691.444 66,041,000 52.650.444 44.4 

1921 115,212,000 13.151.472 128,363,472 75,942,000 52.421,472 40.8 

1922.. 144.544,000 14,145,830 158,689.830 84,580,000 74.109,830 46.7 

1923_. 321.694.742 11,670,988 333.365,730 131,434,000 201.931.730 60 6 

1924— 259,707,978 14,850.207 274,558,185 189,692,000 84.866,185 30.9 

1925__ 218,877.358 5,197.777 224,075.135 187,789,000 36.286,135 16.2 

1926— 221,872.505 7.319,608 229.192.113 204.915,000 24.277,113 10.6 

1927— 261,316,836 4,566,263 265,883.099 212,897,000 52,986,099 19.9 

1928— 311.020,653 2,435.219 313,455,872 251,252,929 62,202.943 19.8 

1929— 561.221.542 2,323.265 563.544,807 355,531,160 208,013.647 36.9 
1930.. 547,985,826 6.131,075 554,116,901 322,149,891 231.967,010 41.9 

1931 385,509,561 1.750.252 387,259,813 312.663,259 74.596.554 19.3 

1932.. 280,333.931 1.742,170 282,076.101 262.013.774 20,062,327 7.1 

1933-. 271,382,043 2.472.302 273,854.345 259,360,995 14,493,350 5.3 

1934.. 283.142,012 4,957.292 288.099.304 269,524,394 18,574,910 6.4 

1935.. 307.283.874 11.831,258 319,115.132 296.045.463 23.069.669 7.2 

1936— 338.079.684 5.784.611 343.864,295 319.403.271 24.461,024 7.1 

1937— 343,142,734 11,621,318 354,764,052 335.800.628 18,963.424 5.3 
1938.- 362.043,223 13,792.206 375,835,489 337,601,673 38.233,816 10.2 
1939— 348,721.616 27,129,010 375.850,626 342,545,260 33,305,366 8.9 

Totals. 6. -944. 092, 118 278.889.371 7,222.981,489 5.066,485.897 2,156,495,592 
(cumulative) 

Production data for years prior to 1923 were prepared from records of oil 
companies and gas companies and from gas-oil ratio computations; for years 1923 to 
1929, inclusive, from gas company records: subsequent to 1929, from records of State 
Division of Oil and Gas. 

Although the West Coyote field was discovered in 
1906, it was not until 1914-1917 that the fields in the 
eastern portion of the Los Angeles Basin showed promise 
of developing large-volume gas production. The con- 
siderable increase in production that accompanied the 
successive completion of the Montebello and later Basin 
fields is clearljr shown on Fig. 12. 

In the San Joaquin Valley, the Elk Hills field (Kern 
County) was discovered in 1919. As is the case in the 



34 



Development and Production 



[Chap. I 





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Natural Gas Field s — B auek and Dodge 



35 



Buena Vista Hills, a dry gas zone exists here, lying 
above the oil zone. Standard Oil Company's Hay No. 7 
(See. 36, T. 30 S., R. 23 E., M. D.), a dry gas well pro- 
ducing from a depth of approximately 2,100 ft. from 
sands in the San Joaquin clay (Pliocene), has produced 
more gas than any other single well in the country. 
This section now forms a part of U. S. Naval Reserve 
No. 1, and no production is being taken from the gas 
zone at the present time. 

Turning again to the Los Angeles Basin, reference 
to Pig. 12 will show the effect on production of the devel- 
opment of the "town-lot fields" in 1922-1924; Fig. 13 
shows the resulting rapid increase in production and 
enormous wastage of gas in the Huntington Beach, Long 
Beach, and Santa Fe Springs fields. A prolific dry gas 
sand was developed in the Santa Fe Springs field, but 
unsatisfactory protection of the producing horizon 
resulted in the dissipation of the gas in a short time. 

The rapid decline which follows every unrestricted 
town-lot development, caused increased activity in other 
areas. Four additional fields were developed in the 
Basin, but the most important discovery of this period 
was that of the deeper sands in the Ventura Avenue field 
in 1925. 

In 1927 dry gas was found at Buttonwillow, Kern 
County. This was the first production of dry gas, not 
associated structurally with an oil field, to be discovered 
in the San Joaquin Valley, and the first of any impor- 
tance in the State. This discovery was soon over- 
shadowed by the completion of the first well in 
Kettleman Hills in 1928. Kettleman Hills proved to be 
a field of the first magnitude, and ushered in a new era 
of utilization of natural gas throughout the State. 

The second mad scramble for production in the Long 
Beach and Santa Fe Springs fields took place in the 
latter part of 1928 and extended through 1929 and 1930. 
It was the result of the discovery of deeper zones in the 
existing fields. The greatest gas wastage in the State's 
history took place during these years. 

DEVELOPMENTS IN THE PAST DECADE 
In 1930 a deep zone was discovered in the North 
Bel ridge field. It has considerable importance from a 
gas standpoint as the gas cap associated with oil is 
extensive and under very high pressure. 

The accompanying figures and Table I show the 
effect of the production decline in many fields, and of 
the curtailment and efforts at conservation which fol- 
lowed the enactment by the Legislature of the Gas Con- 
servation Act of 1929. Since that time, the amounts of 
unconsented gas have been relatively small in spite of 
additional discoveries and some town-lot development 
in Huntington Beach (1934-1935), Wilmington (1938- 
1939), and Montebello (1939-1940). 

FURTHER DRY GAS DISCOVERIES 

The two most important dry gas fields in the State, 
not associated structurally with oil production, are 
McDonald Island and Rio Vista, in central California. 
These fields, which lie in the so-called river delta region, 
were discovered in 1936. A number of minor dry gas 
fields — including Semitropie, Trico, Tulare Lake, and 
Chowchilla — were also discovered about this time in the 
San Joaquin Valley. These latter fields have proven 
to be of no great importance because of limited pro- 
ductive area or low heating value of the gas. 



RECENT DEEP FIELDS IN SAN JOAQUIN VALLEY 
The year 1937 marked the first successful attempt for 
production at depths much in excess of 10,000 ft. in the 
San Joaquin Valley. The Rio Bravo field was the first 
of such developments, and discoveries at even greater 
depths are continuing today. Deeper drilling in the 
Kettleman Hills in 1938 encountered production in the 
Eocene and helped to strengthen that field's claim to 
first position among California's oil and gas fields. 

DEVELOPMENT OF UTILIZATION 

To the Santa Maria Gas Company goes the honor of 
being the first, gas utility company in California to serve 
straight natural gas to its customers (1907). In 1910 a 
line 40 miles in length was laid from Taft in the Buena 
Vista Hills to Bakersfield; in 1912 and 1913 a line from 
the same place was laid to Glendale and Los Angeles. 
April 28, 1913, marked a new era in southern California 
history as the day of the first delivery of natural gas 
from the San Joaquin Valley. 

During 1914 the cities adjacent to the eastern fields 
of the Los Angeles Basin were served with natural gas, 
and in December. 1915, the first Los Angeles Basin gas 
was delivered to Los Angeles. In these earlier years, 
however, domestic consumers were not served straight 
natural gas, the gas from the fields being reformed or 
blended with artificial gas to a B.t.u. value of 600 to 850 
per cu. ft. 

By January, 1927, all of the Los Angeles Basin area 
was served with 100% natural gas. Industrial utiliza- 
tion which had started in 1922 and 1923 with the large 
volumes of gas then available, continued to increase. 

During August. 1929, natural gas reached San Fran- 
cisco Bay area from Kettleman Hills ; later service was 
extended to Stockton and Sacramento. January, 1940. 
nearly every important community in California was 
served with natural gas. This embraces 99 f /< of the 
total number of gas consumers. 



TABLE 


III— CALIFORNIA: 


NATURAL 


GAS UTILIZATION* 




By Gat Companiet 


;•• 








Central and 












Sort hi in 


Southern 




«» oil 




Year 


California 


California' " * 


Rub-total 


companies 


Total 


1930 


26,507.468 


107,641,117 


134.14S.5S.-, 


188.001,306 


322,149,891 


1931 


52.083.555 


106,469.578 


158.553.133 


154.110,126 


312,663.2511 


1932 


46.474.415 


83.282.2S0 


129.756.695 


132,257,079 


262,013,774 


1933 


51.643.562 


92,085,170 


143.728.732 


115.632.263 


259,360.995 


1931 


56.493,462 


104.104,666 


160.598,128 


108,926,266 


269.524.394 


1935 


63.537,829 


110.453,608 


173.991.437 


122,054.026 


296,045.463 


1936 


69.969,346 


118,975,530 


188.944.876 


130,458,395 


319,403.271 


1937 


76.726,384 


123.714,721 


200.441,105 


135,359,523 


335.800,628 


1938 


78,045.090 


115,626.782 


193.671.872 


143,929,801 


337.601,673 


1939 


94,598,185 


124,573.252 


219,171,437 


123.373,823 


342.545.26(1 



* All data in M.CU.ft. 
** For resale, company use and unaccounted for. 
*** South of Fresno and Paso Robles. 

SIGNIFICANCE OF THE INDUSTRY 
The natural gas industry in California has developed 
steadily. During the past three years, natural gas has 
stood third in value among the mineral products of the 
State, being exceeded only by oil and gold. Since 1907, 
a trrowth in yearly revenues from nothing to over $80.- 
000,000 per year has taken place. The number of cus- 
tomers served has likewise increased, until California 
now holds top place among the States of the Union; 
it has held this place for the past five years. At the end 
of 1939, more than 1,700,000 domestic and commercial 
customers and 4,600 industrial and pumping plants were 
using natural gas. Total population in the area served 
is 5,600,000. During a corresponding period, pipe lines 



36 



Development and Production 



[Chap. I 



have been extended from a few miles to over 23,500 
miles. The investment in lines, plants, and facilities 
exceeded $285,000,000 by the end of 1939. 

RELATIONSHIP BETWEEN GAS AND OIL 
PRODUCTION 

The supply of casinghead gas from an oil field is 
dependent almost entirely upon the amount of oil being 
produced from that field. The gas-oil ratio is defined as 
the number of cubic feet of gas (measured under stand- 
ard surface conditions) produced with each barrel of oil. 
It can be varied somewhat for individual wells, but in 
the ordinary field (taken as a whole) the production of 
gas is directly dependent upon the oil production. Cer- 
tain exceptional fields exist, such as Kettleman Hills and 
North Belridge, where (under present conditions of cur- 
tailment) the allowable oil production can be obtained 
from low gas-oil ratio wells. At times of greater gas 
demand, however, these low ratio wells can be closed in, 
and an equivalent oil production obtained from gas cap 
wells, greatly increasing the amount of gas available to 
the gas companies. Such changes are necessary to adapt 
the gas production to the load fluctuations. These fluc- 
tuations occur seasonally; even over the week-ends, with 
the cessation of industrial activity on Saturdays, a sud- 
den and serious decrease in gas utilization takes place, 
and continues until the following Monday. 

In certain other fields, injection of the surplus gas 
into partially or wholly depleted sands is resorted to 
during periods of low demand. These surpluses, together 
with such withdrawals from storage as can be handled, 
are then made available to the gas companies in time of 
cold weather or other periods of heavy demand. 

Pig. 12 illustrates the seasonal variation in load, or 
utilization, on a monthly basis. If such a diagram were 
prepared on a daily basis, an equally wide variation 
would be shown between the days of the week. 

IMPORTANCE OF DRY GAS FIELDS 
The dry gas fields of California form a valuable 
reserve which may be drawn upon in time of heavy 
demand, and up to the present time they have served 
the industry in this manner. Where such fields lie close 
to a large metropolitan market, use of dry gas may 
supplant the use of casinghead gas from the oil fields, 
particularly if the oil field is at a considerable distance 
from the market. Normally, however, since the dry gas 
is commonly of a lower heating value than the casing- 
head gas, it may best be utilized by blending with the 
higher B.t.u. oil field gas. Dry gas deposits can be con- 
served in place indefinitely, while casinghead gas, for the 
most part, must be utilized as produced. Ultimately, as 



the gas associated with oil is exhausted, dry gas fields will 
assume a major importance in California ; but up to the 
present time they have been relatively insignificant as 
illustrated by the statistics shown in Table I. 

TABLE V— SUMMARY OF CALIFORNIA FIELDS HAVING 
IMPORTANT GAS RESERVES* 









Approx. mini- 










Zones contain- 


mum depth 


Approx. 






Year of 


ing gas or 


to top of 


thickness 




Central California 


discovery 


oil and gas 


zone f feet ) 


(teetf 


Qeologic age 


McDonald Island 


. 1936 


dry gas zone 


5,200 


250 


Eocene 


Rio Vista— 


1936 


dry gas zone 


3.800 


350 


Eocene 


San Joaquin Valley 










Coalinga Extension 












North 


.. 1939 


oil and gas 


7,900 


300± 


Eocene 


Coalinga Extension 












South 


1938 


oil and gas 


6,600 


800± 


Eocene 


Kettleman Hills 












N. Dome 


(1928 


oil and gas 


6,000 


1,600 


Miocene 




(1938 


oil and gas 


10,500 


600-*- 


Eocene 


North Belridge 


(1930 


oil and gas 


5.000 


300 


Miocene 




(1935 


oil and gas 


7,400 


350 


Oligocene? 


Buena Vista Hills. _ 


. 1909 


dry gas zone 


1,100-H 


500-1- 








oil arid gas 


2.200-+- 


600-H 


Lower Pliocene 


Elk Hills 


. 1919 


dry gas zone 
oil and gas 


1,400-1- 
2,400-H 


500-1- 
800 -H 






Lower Pliocene 


Rio Bravo 


1937 
1936 


oil and gas 
oil and gas 


11.200 
7.600 


200 
100 


Miocene 


Greeley 


Miocene 








11,250 


200 


Miocene 


Coles Levee 


1938 


oil and gas 


8,250 


900 


Miocene 


Ten Sections 


1936 


oil and gas 


7.800 


600 


Aiiocene 


Coastal 












La Goleta 


1929 
1916 


dry gas zone 
oil and gas 


4,100 
1,000 


150 

7,000± 


Miocene 


Ventura Avenue 


Pliocene 


Lot Angeles Basin 












Inglewood 


1925 


oil and gas 


1,100 


2,500-1- 


Pliocene 


Dominguez 


1923 


oil and gas 


1,000± 


3,000± 


Pliocene 
(Pliocene 
(Upper Miocene 
(Pliocene 
(Miocene? 


Wilmington 


. 1936 


oil and gas 


2,100 


2,400± 


Long Beach 


. 1921 


oil and gas 


2,300 


6.4O0± 


Huntington Beach. _ 


.. 1920 


oil and gas 


2,000 


2.700± 


(Pliocene 
(Upper Miocene 


Montebello 


1917 


oil and gas 


1,750 


3.400 ■+- 


Pliocene 


Santa Fe Springs 


_ 1919 


oil and gas 


2,000-t- 


3,600-t- 


Pliocene 


West Coyote 


1908 


oil and gas 


3,300 


2.000-1- 


Lower Pliocene 


Brea Olinda 


1897 


oil and gas 


200 


3,200-1- 


Pliocene 



* This summary includes the fields having the most important gas reserves. Such 
fields as Buttonwillow, Santa Maria, Elwood, Rosecrans, South Mountain, Seal Beach, 
Playa del Rey, Torrance, Richfield, Tracy, Trico, and Marysville Buttes all produce gas 
but in relatively small quantities and the sum of the reserves in all of these fields is a 
relatively small percentage of the total reserves in the State. The fields shown in the 
summary are those which have substantial reserves to be produced at some future period. 

** From top. to bottom of entire producing interval. 

POSITION OF GAS IN STRATIGRAPHIC COLUMN 

Commercial deposits of natural gas occur in strata 
ranging in age from Cretaceous to Pleistocene, but by 
far the greatest part of the production obtained to date 
has come from the Pliocene and upper Miocene. 

The gas obtained from the shallow wells near Stock- 
ton, though historically the earliest production developed, 
came from geological formations most recent in age, 
namely Pleistocene. Some of the latest fields discovered, 
such as Coalinga Extensions and the Avenal zone of 
Kettleman Hills, are producing from strata of Eocene 
age or older. In the Sacramento Valley, as at Marysville 
Buttes, gas is obtained from rocks of Cretaceous age. 

Bibliography: Boone, A. R. 37; Davis, R. E. 38; Hoots, H. W. 
~ 37 ; Wall Street Journal 40. 



39a ; Uren, L. C 
TABLE IV— ANALYSES OF TYPICAL GAS SAMPLES FROM CALIFORNIA FIELDS* 



Sorth Dome Xorth 

Sample from Kettleman Belridge 

Hills OH. C.H. (Wagon- 
Kind of gas (Temblor) wheel) 

CC-2 ___% 1.30% 

CH« 85.36 91.21 

CnHe 8.62 3.61 

CnHs 5.10 1.94 

ISO-C4H10 0.4S 0.36 

N-C«Hio 0.44 0.69 

Cr,Hi:-(- 0.89 

Calc. B.t.u 1,173 1,089 

•Reproduced from Bauer, R. M. 



39 



Ten 
Sections 

C.H. 

0.50% 
87.97 

8.05 

3.14 

0.16 

0.16 

0.02 

1,118 
p. 103, 



Rio 
Bravo 
C.H. 

0.50% 
83.32 
10.31 

5.41 

0.36 

0.10 



1,174 



Semi- 

Tropie 

Dry 

0.1% 
98.7 
0.0 



1.2 
992 



Rio 

Vista 
Dry 
c 

94.79 ' 
2.82 
0.72 
0.17 



1.50 
1,030 



Coyote 
Hills 
C.H. 

— % 

85.4 
8.0 
5.5 
0.6 
0.5 



1,178 



Domin- 
guez 
C.H. 

0.91% 
89.42 
6.05 

2.95 

0.36 

0.28 

0.03 

1,105 



Long 
Beach 
C.H. 

0.50% 
86.76 
7.19 
4.28 
0.66 
0.61 



1,152 



Santa Fe 
Springs 

C.H. 

0.40% 
85.09- 
10.23 

4.15 

0.08 

0.05 



1,187 



Wilming- 
ton 
C.H. 

3.00% 
88.92 
4.27 
3.42 
0.25 
0.14 



1.057 



Ventura 
Avenue 
C.H. J 

0.40% 
89.13 
4.90 
4.63 
0.51 
0.43 



1,134 



Table No. 5. 
It should be noted that the examples of dry gas analysis shown are of unusually high heating value, much higher than the values 
obtaining for such dry gas areas as Stockton, Chowchilla, and other minor San Joaquin Valley gas fields. The lower heating value of 
such gases is due to the complete absence of the heavier hydrocarbons and the presence of varying amounts of nitrogen and carbon 
dioxide. 



Chapter II 

Exploration 



CONTENTS OF CHAPTER II 



Page 
Development of Engineering Technique and Its Effect Upon Exploration for Oil and Gas in California, By- 
Lester C. Uren 39 



Mechanics of California Reservoirs, By Stanley C. Herold 63 

Geophysical Studies in California, By F. E. Vaughan 67 

Geochemical Prospecting for Petroleum, By E. E. Rosaire 71 



38 



Exploration 



[Chap. II 



LAKE 



^COLU 



lusa © /7a" . 

sa ; TUBAC ^ 



./ 



v> 



\ 



\ 



S— . \ ft 

/ VYOLO N 



WOOOLAMD @ 



YUBA. 

)(•> marysville/ c. 

» Iau.Jn? 7 el dorado 

•^--i— / ®PLACERVILLE 

, 'Sacramento 
o V 




,y 



MARKLEEVILLE 

® (\ 

ne\ v 



• y --AMADOR .— i ALP ' 

O m \ NAPA \ -f 4> 



outline: map 

OF PORTION OF 

CALIFORNIA 

SHOWING LOCATION OF 

OILFIELDS and DISTRICTS 




Note : Figures rndicata ^s. 


number of Or/f/e/d Map. ^^5 


Sfo map published for (§ 


f,e/ds located by lefer jj] 


MAP 




NO. 


FIELD LOCALITY 


19 


ARROYO GRANDE 


17 


BARDS DALE 


10 


BELRIDGE 


6 


BEVERLY HILLS 


4 


BREA-OLINDA 




BUTTES (GAS') a 


54 


BUT TONWILLOW (GAS) 


55 


CANAL 


55 


CANFIELD RANCH 


43 


CAPITAN 


3 


CASMALIA 


2 


CAT CANYON 


14 


COALINGA 


55 


COLES LEVEE 


17 


CONEJO 


4 


COYOTE HILLS 


12 


DEVILS DEN 


29 


DOMINGUEZ 


14 


EAST COAUNGA 




EXTENSION 


48 


EDISON 


15 


ELK HILLS 


52 


EL SEGUNDO 


40 


ELWOOD 8. LA 




GOLETA (.GAS) 


48 


FRUITVALE 


53 


GREELEY 


26 


HUNTINGTON BEACH 


31 


INGLEWOOD 


36 


KETTLEMAN HILLS 


13 


KERN RIVER 


52 


LAWN DALE 


3 


LOMPOC 


20 


LONG BEACH 




LOS ANGELES b 


1 1 


N. BELRIDGE & 




LOST HILLS 


9 


N. MIDWAY & 




McKITTRICK- 




TEMBLOR 


44 


MESA 




MtDONALD ISL.(GAS)c 


7-8-9 


MIDWAY-SUNSET 


37 


MONTEBELLO 




MOODY GULCH d 


48 


MOUNTAIN VIEW 



34 


MT POSO 


31- 


18 


NEWHALL 


42" 




NEWPORT e 


52' 


16 
18 


pV,^ 56 PALOMA 


28 


42 


PLAYA DEL REY 




34 


POSO CREEK 


c 


4 1 


POTRERO 




46 


RICHFIELD 




33 


RINCON 




53 


RIO BRAVO 




57 


RIO VISTA (GAS) 




35 


ROUND MOUNTAIN 




30 


ROSECRANS 




6 


SALT LAKE 




27 


SANTA FE SPRINGS 




2-3 


SANTA MARIA 




51 


SANTA MARIA 
VALLEY 




1 7 
1 


SANTA PAULA 
SARGENT 




32 


SEAL BEACH 




54 


SEMITROPIC (GAS) 




1 7 


SESPE 




18 


SIMI 




1 7 


SOUTH MOUNTAIN 




55 


STRAND 
SUMMERLAND f 




55 


TEN SECTION 




28 


TORRANCE 

TRACY (GAS) q 

VENTURA 




16 




54 


WASCO 

WHEELER RIDGE h 




38 


WHITTIER 




50 


WILMINGTON 





Fig. 



13 A. Index map, prepared by the State Division of Oil and Gas, to show locations of oil 
fields and districts in California. The numbers correspond to maps, which may be obtained 
from the Division of Oil and Gas. 



DEVELOPMENT OF ENGINEERING TECHNIQUE AND ITS EFFECT UPON 
EXPLORATION FOR OIL AND GAS IN CALIFORNIA 



By Lester C. Uben* 



OUTLINE OP REPORT P A0E 

Introduction 39 

Early discoveries and exploitation 39 

Development of modern exploration methods 40 

Geophysical exploration 40 

Aerial photography 41 

Drilling for structural information 41 

Importance of continuation of exploration activity and of 

recurrent discovery of new fields 42 

Development of drilling equipment and technique 42 

Early drilling by cable method 42 

Rotary method of drilling 44 

Combination rig 44 

Standard circulating system of drilling 44 

Improvement in derrick and rig design and construction 45 

Rotary coring equipment 46 

Improvements in rotary drilling bits 47 

Bit-pressure control devices 48 

Hydraulically controlled rotary equipment 48 

Development of long, heavy drill collars 48 

Development of rapid rotational speeds 48 

Improvement in drill pipe strength and design 48 

Improvement in drilling fluids used in rotary drilling 48 

Improved and larger capacity power plants 50 

Larger capacity and higher pressure circulating pumps 51 

Trend toward unitary construction of drilling equipment 52 

Stand-by equipment 52 

Greater utility of portable rigs 52 

Trend toward deeper drilling 52 

Improvement in materials employed in manufacture of drill- 
ing equipment and well equipment 52 

Larger and heavier equipment for deeper drilling 52 

Improvement in transportation facilities 53 

Improvements in well casing and casing practice 53 

Water exclusion practices 54 

Locating sources of water incursion in wells 55 

Well surveying equipment 55 

Directional drilling 56 

Improvement in well completion methods 57 

Improvement in formation sampling and testing technique 58 

Wall-sampling devices 58 

Heavy mineral segregation and petrographic inspection 59 

Identification of micro-fossils for correlation 59 

Electrical logs 60 

Testing to determine fluid content of strata penetrated by 

wells 61 

Analysis of formation waters 61 

Improved field development practices based on better knowl- 
edge of deep-seated reservoir conditions 61 

INTRODUCTION 

The story of the search for petroleum in California 
and of the development of her many oil and gas produc- 
ing fields, is the story of the petroleum industry itself. 
Almost from the inception of the industry in the United 
States, California has been recognized as a region offering 
great promise as a potential producer of oil and gas. The 
full gamut of methods and equipment, from the most 
primitive to the most modern, has found application 
here. Indeed, it would appear that during the last three 
decades, the California fields have been the proving 
ground for most of the innovations that characterize the 
highly scientific petroleum industry of today. Likewise, 
the California industry has been the training ground for 

'Professor of Petroleum Engineering, University of California. 
Manuscript submitted for publication November 27, 1939. 



many of the technical men who have been largely respon- 
sible for the development of the industry to its present 
high plane of efficiency. 

In the present chapter, an effort will be made to trace 
briefly the development of methods of petroleum explora- 
tion and oil-field development, from the early days of the 
California industry to the present time, with particular 
emphasis upon the more modern methods and equipment 
utilized in the present-day industry. The period is one 
which extends from the early '60 's when the first 
primitive efforts were made to develop commercial pro- 
duction in California, through the subsequent seventy- 
odd years of gradual improvement in engineering tech- 
nique. 

EARLY DISCOVERIES AND EXPLOITATION 

The early years of the petroleum industry in Cali- 
fornia require little comment, as they were productive of 
no innovations that seem important in retrospect. The 
methods employed were those that had been found effec- 
tive in development of the Pennsylvania fields. Little 
was known of the geology of the region, or of the influ- 
ence of geologic structure on oil accumulation. The wells 
were located in the vicinity of outcrops that gave evi- 
dence of the presence of petroleum and, being shallow, 
primitive cable-tool equipment proved adequate in drill- 
ing them. California was a region isolated from popu- 
lous sections of the country by long stretches of desert 
or by many days of ocean travel, and the market demand 
for petroleum products in the region served by the Cali- 
fornia industry was small. At most times, a surplus of 
oil existed ; prices were low and there was little incentive 
for active search for new reserves. 

Prior to 1894, all commercial production of crude 
petroleum in California was secured from Ventura 
County, particularly in the vicinity of Newhall and 
Ojai, where production was found in several shallow 
pools. It is probably a fair statement that the operators 
in these early pools had little understanding of the intri- 
cate geology of this region, and new pools were located 
primarily along trends from well marked outcrops and 
existing producers. 

An interesting development of the early '60 's in 
Ventura County, was the driving of a number of tunnels 
for oil drainage. "With portals in the ravine below the 
precipitous slopes of Sulphur Mountain, these tunnels, 
though less than a thousand feet long, were so situated 
that they penetrated oil sands well below the surface. 
For many years they continued to produce small quan- 
tities of oil. Drainage of oil through mine openings had 
previously been practiced in a primitive way in other 
parts of the world, but the Sulphur Mountain tunnels 
are of interest as the first successful enterprise of the 
kind in the western hemisphere, and there have been few 
since. 

In 1894, the Los Angeles and Salt Lake fields were 
discovered in what are now thickly populated portions of 



40 



Exploration 



[Chap. II 



the City of Los Angeles. Interest was attracted to these 
areas by nearby brea pits and surface outcrops that gave 
promise of oil production from shallow horizons. Also, 
in the same year, successful wells were drilled on the 
coast, near Summerland in Ventura County, and a por- 
tion of this field, extending out from shore under tide- 
lands, was later exploited by shallow wells drilled from 
piers — probably the first successful underwater develop- 
ment of an oil field. First production in the San Joaquin 
Valley was in the Coalinga field in 1896, this being the 
first California field to attain an annual rate of produc- 
tion in excess of a million barrels per year. Again, bitu- 
minous outcrops in the vicinity attracted attention and 
the early wells were located on monoclinal structures that 
obviously had yielded some of their oil to the outcrops. 
The early wells in these fields were but a few hundred 
feet deep, but down-dip exploration soon disclosed 
deeper, more prolific sands. 

Discovery of the McKittrick and Midway-Sunset 
fields, situated much like the Coalinga field, on the east- 
ward flanks of the Coast Range, and presenting a very 
similar geological and lithological picture, followed in 
1898 and 1900. Across the Valley, east of Rakersfield, 
obvious surface indications led to the discovery of the 
Kern River field, also in 1900. Again, the early wells were 
less than a thousand feet deep. Likewise, the Brea-Olinda 
district in the Los Angeles Basin, and the Santa Maria 
field, near the coast in northern Santa Barbara County, 
were developments of the few years preceding and fol- 
lowing the "turn of the century," which might well be 
regarded as the end of the first epoch of petroleum de- 
velopment in California. Gross production of all Cali- 
fornia fields, up to and including the year 1900, was 
14,378,875 barrels and the maximum annual production 
of the period, attained in the year 1900, was only 4,324,- 
000 barrels. 

"While geological knowledge played little part in the 
discovery of these early California fields, geologists 
were not without knowledge of the role of structure and 
its influence on oil and gas accumulation. The anticlinal 
theory of oil accumulation had been proposed and by 
1900 was rather generally accepted, but it had not as yet 
become the custom for would-be producers of petroleum 
to seek geological advice. 

DEVELOPMENT OF MODERN EXPLORATION METHODS 

After the more obvious surface seepages had been 
noted and the localities about them explored with test 
wells, it came to be recognized among the larger and 
better informed oil producers that further progress in 
the finding of new pools was to bo made only by appli- 
cation of the geological sciences (Lahee, F. H. 31). 
Accordingly, many producers began to employ geologists 
to advise in the selection of well sites and eventually 
most of the larger oil companies organized geological 
departments to engage in widespread reconnaissance and 
detailed geologic studies of the more promising areas. 

It was early observed that most of the California oil 
deposits were confined to rocks of Pliocene and Miocene 
age and that accumulations were customarily found in 
dome or anticlinal structures or in "buttress" formations 
on the flanks of folds or against unconformities or fault 
planes and in definite relation to certain shale bodies 
that were likely "source rocks." Accordingly, early in- 



terest centered on these geologic horizons, and test wells 
were located in areas where they were within reach of 
the drill and where structural traps were observed to 
exist. Once these more favorable areas were selected, 
the work of the geologist in the field resolved itself 
largely into detailed studies of dip and strike of strata 
and the gathering of information helpful in forming an 
accurate picture of subsurface structure (Cox, G. H. 21). 
Surface locations for test wells were then selected at 
points that would permit them to intersect the prospec- 
tive oil reservoir rock at or near its structural crest. 

The science of paleontology was found to be a useful 
tool of the geologist in determining the approximate 
geologic age of formations exposed at the surface, as 
well as those penetrated by the wells. Certain fossil 
markers came to be recognized as characteristic of dif- 
ferent geologic intervals and broad correlations of for- 
mations in different locations became possible. Out of 
this knowledge grew the science of correlation by identi- 
fication of micro-fossils. 

GEOPHYSICAL EXPLORATION 

The conventional methods of the geologists, based 
largely upon surface areal studies, served well enough 
in the foothill regions where outcrops were plentiful and 
the broad structural features were fairly apparent. 
Eventually, however, as these more obvious structures 
were explored and tested, it became necessary to extend 
the search for new fields into areas where nature had 
been less generous in providing surface indicators. 
Geologists had long held the theory that oil-bearing 
structures might be found buried beneath the horizon- 
tally disposed sediments of the San Joaquin Valley, in 
areas where surface studies disclose little or nothing of 
deep-seated structural conditions. Particularly was this 
likely to he true where stratigraphic unconformities 
existed. 

Development and application of geophysical methods 
of exploration during the last two decades have aided 
greatly in identifying structural features in localities 
where surface exposures were inadequate. Early efforts 
to apply geophysical methods in California were not 
successful, and, for a time, it was thought by many 
geologists that they would not be found helpful under 
the conditions presented in this region. It was consid- 
ered that the strata overlying the oil measures were too 
much alike in density, elasticity, and other physical and 
lithologic characteristics to afford satisfactory reference 
horizons upon which to make observations. Torsion bal- 
ance surveys were made in the California fields during 
the early '20 's by some of the more forward-looking oil 
companies. Some companies made extensive mag- 
netometer surveys; others se.ismic surveys. While the 
early efforts to apply these methods were not successful 
in discovering any new producing fields in California, 
gradual perfection of equipment and methods eventually 
began to produce more encouraging results. Particu- 
larly was this true of the reflection seismic method, now 
widely employed. 

Within the last few years, many new California oil 
and gas fields have been discovered as a direct result of 
geophysical surveys. Notable among these are a highly 
prolific group of oil and gas fields situated in the area 
to the west and northwest of Bakersfield (i.e., Ten Sec- 



Development of Engineering Techniqu e — U een 



41 




i ■ ^ § 






4? 













o o 

c a 

Si 

£ 



a = 






tions, Wasco, Greeley, Cole's Levee) and several struc- 
tures producing dry gas in the delta region of central 
California (Tracy, Rio Vista, McDonald Island). 

Some authorities believe that we may have already 
exhausted the opportunities for application of geophysi- 
cal methods in the finding of new oil and gas fields in 
California, but it seems more reasonable to believe that 
with further improvements in design of geophysical 
instruments and with better understanding and interpre- 
tations of the results of geophysical surveys, more fields, 
hitherto overlooked, will be found. There would also 
seem to be opportunity for more detailed studies of 
prospective areas than have yet been made. Geophysi- 
cal methods may be of great help in obtaining a clear 
picture of broad structural features of an entire district. 
For example, they may be of aid in deciphering Cali- 
fornia's extensive system of block faults. In any case, 
it is quite certain that geophysics will henceforth be 
regarded as a valuable tool of the geologist in his search 
for new oil reserves and that geophysical data will play 
an important role in future exploration (Lahee, P. 
H. 31). 

AERIAL PHOTOGRAPHY 

Older methods of gathering topographic detail in 
preparing maps for use in geologic reconnaissance have 
been supplemented during the last two decades by 
methods of mapping from the air. Photographs system- 
atically taken from an aeroplane flying at constant ele- 
vation, in straight courses over the area to be mapped, 
are later fitted together to form a complete mosaic or 
"aerial map." Such maps possess a pictorial value 
beyond that of any other kind of topographic map and 
have to a considerable extent, supplanted ordinary 
f opographic maps prepared by plane-table, transit, level 
and other conventional methods (English, W. A. 30). 
They have the additional advantage of being less costly, 
and they may be more rapidly assembled. Occasionally 
the outcropping strata are so clearly apparent on the 
photographs, especially when examined under the stereo- 
scope, that it is possible to identify anticlinal structures 
without gathering the usual field data; but generally 
they are employed merely as a base upon which to 
assemble data gathered in the field survey. 

DRILLING FOR STRUCTURAL INFORMATION 

Where surface alluvium obscures outcrops to such 
an extent that the usual methods of gathering field data 
become impractical, the geologist may, resort to the 
drilling of shallow wells merely for subsurface informa- 
tion. Small diameter wells, but a few hundred feet deep, 
cheaply drilled with portable drilling outfits, may afford 
stratigraphic information very helpful in determining 
the dip and strike of beds, often with sufficient accuracy 
to disclose the geologic structure. In localities where 
unconformities intervene between shallow and deep- 
seated formations, it will often be necessary in drilling 
wells to penetrate the formations below the plane of the 
unconformity, before the structural and stratigraphic 
conditions at depth may be determined. Cores taken at 
intervals will disclose the character of the sediments, 
and with the aid of modern methods of core orientation, 
the dip and strike of beds may be estimated. Measured 
depths to a recognizable marker bed in three wells, suit- 



42 



Exploration 



[Chap. II 



ably spaced, afford a basis for determining the strike 
and dip of beds without the aid of cores. 

IMPORTANCE OF CONTINUATION OF EXPLORATION 

ACTIVITY AND OF RECURRENT DISCOVERY 

OF NEW FIELDS 

Available supplies of petroleum in present known 
California fields, have lately been estimated at 3.2 billion 
barrels, or about 12 years supply at the 1938 rate of 
production (American Petroleum Institute 39, p. 61). 
On January 1, 1938, California's natural gas reserve was 
estimated at 6.9 trillion cubic feet (Bauer, R. M. 39). At 
the current rate of withdrawal of about 350 billion cubic 
feet yearly, this is about 20 years' supply. While 
these estimates are probably conservative, yet when one 
considers the great economic importance of the oil and 
gas industries of California and the necessity for main- 
taining a continuing supply of essential petroleum prod- 
ucts, they represent a rather slender reserve. Further- 
more, because of decline in productivity of wells and 
fields, it would be difficult to maintain the current rate 
of production from these sources for more than a few 
years. Most of our current supplies of oil and gas are 
derived from recently discovered fields in flush produc- 
tion, and we are vitally dependent upon recurrent dis- 
covery of new sources of supply if we are to maintain or 
increase our current rate of production. Hence, it is 
important that those engaged in seeking new oil and gas 
fields be given every encouragement. If a suitable mar- 
gin of profit is assured to cover the risks inherent in this 
highly speculative phase of the petroleum industry, we 
may hope to find many additional oil pools. Yet the cur- 
rent production rate is one that demands a considerable 
continuing activity in new exploration and development 
work, and increasing difficulty and cost of finding new 
reserves requires an ever-increasing amount of new capi- 
tal to maintain the existing reserve. Inevitably, the time 
will come when we can no longer maintain the reserve : 
when the amount of new capital available for exploration 
and development will no longer be sufficient to find, each 
new year, as much oil as is consumed. Whether this time 
is near at hand or remote is a matter of opinion hinging 
upon one's ideas of the magnitude and availability of the 
undiscovered reserve. 

New exploration may be effective in finding additional 
reserves in one of three ways : ( 1 ) by drilling in hitherto 
unexplored areas; (2) by exploring lateral extensions of 
areas already productive, and (3) by seeking deeper 
productive formations in present producing areas. Of 
late, new supplies of oil in all three categories have been 
found, and there would seem to be opportunity for fur- 
ther discoveries by each method. Geophysics has lately 
been of assistance in finding new and promising areas 
for exploration. Improved deep drilling technique has 
been largely responsible for the success that has attended 
some of these efforts. Certain it is that, without the 
ability to drill to depths greatly in excess of those 
attainable a decade ago, California would even today be 
experiencing a serious shortage of oil. Improved 
methods of exploration go hand in hand with improved 
methods of drilling. Both must undergo continuing 
improvement and development if we are to continue to 
find new reserves to offset the decline in production of 
our older fields. 



DEVELOPMENT OF DRILLING EQUIPMENT AND 
TECHNIQUE IN CALIFORNIA FIELDS 

EARLY DRILLING BY CABLE METHOD 

Prior to about 1910, practically all drilling in the 
California fields was done with cable tools, light portable 
outfits and American "Standard" cable drilling rigs 
being exclusively used. The shallow wells characteristic 
of the early period could be quickly and cheaply drilled 
by this method, but as deeper horizons were exploited, 
wells became considerably more expensive and many 
months were necessary to complete them (Uren, L. C. 
34, Chapt. V, VI). The cable-tool method is not well 
adapted to drilling in the semi-consolidated formations 
characteristic of the California Quaternary and Tertiary, 
much difficulty being experienced due to caving of the 
walls of the wells and in maintaining clearance and 
inserting casing. In many areas, casing had to be driven 
into the wells and individual strings quickly became 
frozen to the walls, so that as many as five telescoping 
strings of casing had to be used to reach depths of 2,000 
to 3,000 ft. 

A large number of the "stripper" wells that are still 
producing in the older California fields were drilled with 
cable tools. Such fields as the West Side Coalinga, Kern 
River, Midway-Sunset-McKittrick, Lost Hills, Belridge, 
Whittier, Los Angeles City, Salt Lake and the older por- 
tions of the Brea-Olinda and Santa Maria fields were 
developed almost entirely by this means. Altogether, 
it is probable that upwards of 15,000 wells have been 
drilled by the cable method in California. Many of these 
are, of course, now abandoned. 




Fig. 15. California-type standard cable drilling rig. (Courtesy 
of McGraw-Hill Book Co., Inc.) 



Development of Engineering Techniqu e — U een 



43 



Ladder -& 



■Double deck 
crown block 

, Crown 
/-'' platform 



Quadruple 
J 'platform 




Reach leyer-' 
Draw Works Side 



Fig. 16 



California type combination drilling rig. (Courtesy of McGraw-Hill Book Co., Inc.) 



44 



Exploration 



[Chap. II 



ROTARY METHOD OF DRILLING 

Successful use of the "hydraulic rotary" method of 
drilling in the Gulf Coast region of Texas, notably in the 
Spindle Top field, led to its early introduction into the 
.San Joaquin Valley fields of California. In the early 
days of its development, the rotary method was thought 
to be suitable only for drilling in the soft, unconsolidated 
and semi-consolidated formations characteristic of this 
region. Drillers familiar only with cable equipment were 
distrustful of the new method and opposed its use. The 
early rotary rigs were light, their parts were poorly 
correlated and of rather primitive design. Frequent 
twist-offs of drill pipe and other mechanical difficulties 
afforded plenty of opportunity for criticism. It was 
charged that the method did not afford a dependable 
means of testing the formations penetrated and that 
prolific oil sands were frequently drilled through without 
recognition of their petroliferous character. Good pro- 
ducing sands were "mudded off" so that they never 
developed their normal productivity. The rotary method 
of drilling was therefore considered unsuitable for explo- 
ration drilling in new areas where a dependable log of 
the formations penetrated was a prime requisite. The 
fish-tail bits at first exclusively used, were unsuited for 
hardrock drilling, and were quickly dulled, so that much 
time was spent in drawing out and replacing drill pipe to 
change bits. Because of the greater power requirements, 
larger drilling crews, greater water consumption, larger 
derrick and higher initial cost for rotary equipment, the 
completion cost of the comparatively shallow rotary- 
drilled wells was as great or greater than when drilling 
was by the cable method. Yet, it was admitted that wells 
could be more quickly drilled by this method — an advan- 
tage under competitive conditions — and that the deeper 
wells could be completed with. fewer strings of casing and 
with a saving in free working diameter at the level of the ' 
reservoir rock. Ability to control high-pressure gas 
encountered in drilling, and to complete wells without 
gas and oil wastage, was admittedly a great advantage 
of the rotary method (Uren, L. C. 34, Chapt. V, VII). 

The real and fancied disadvantages of the rotary 
method, and lack of familiarity with it on the part of 
operators and drillers, were factors that prevented 
prompt and wide-spread adoption of the method during 
the early years, and its introduction was a gradual one 
that extended over a period of many years. Prior to 
1910, practically all drilling in California was with cable 
tools; but by 1920, replacement of the cable method by 
the rotary method was almost complete. This was a 
result of gradual improvement in rotary drilling equip- 
ment and development of greater skill and confidence in 
its use. Also, deeper wells were becoming necessary, and 
with increasing depth, the advantage of the rotary 
method over the cable method became more apparent. 

COMBINATION RIG 

Realizing that each of the two methods of drilling 
possessed certain advantages for particular conditions, 
operators early conceived the idea of combining them so 
that either might be used alternately as conditions 
might warrant. It was found to be feasible to arrange 
all parts of both the rotary and cable equipment under 
one derrick in such a way that the driller could quickly 



change from one method to the other. Rigs so equipped 
were called "combination rigs" and a certain arrange- 
ment of the equipment became characteristic of Cali- 
fornia practice and led to the designation "California 
type combination rig." 

Most of the so-called rotary rigs used in the Califor- 
nia fields have really been combination rigs (Uren, L. C. 
34, Chapt. V, VII). For a time, in the San Joaquin 
Valley fields, operators followed the practice of drilling 
from the surface down to the cap rock to the point where 
the water strings of casing are usually cemented, with 
rotary tools, and then "changing over" and drilling into 
the productive formation and completing the well with 
cable tools. By this practice, sealing off productive for- 
mations with clay from the drilling fluid was avoided : 
an advantage thought to be particularly important in 
drilling into low-pressure reservoir rocks where the sub- 
sequent flow of gas and oil was insufficient to drive all 
deposited clay from the pores of the reservoir rock 
about the walls of the wells. 

STANDARD CIRCULATING SYSTEM OF DRILLING 

In the early days of application of the rotary method 
of drilling in California, much emphasis was given to 
the advantages that the method offered in preventing 
wastage of high-pressure gas and oil during well comple- 




ELEVATION PUMP SIDE 



ELEVATION DRAW - WORKS SIDE . 



Fig. 



17. A California-type rotary drilling rig. (Courtesy of 
McGraw-Hill Book Co., Inc.) 



Development of Engineering Techniqu f — U r e n 



45 



# 




IMPROVEMENT IN DERRICK AND RIG DESIGN 
AND CONSTRUCTION 

Derricks and rigs used in the California oil fields 
until 1920 were constructed almost exclusively of tim- 
ber. The sills, posts, walking beam and rig wheels 
(cable tool and combination rigs) were likewise con- 
structed largely of timber and lumber. Even the corner 
foundations were usually constructed of a mat of timber. 
While mechanically inefficient, as a result of warping 
and yielding under stress, such rigs served well enough 
in drilling the comparatively shallow wells of the period 
in which they were used. Fabricated steel derricks 
made their appearance in considerable numbers in the 
California fields during the early post-war period, par- 
ticularly for drilling in the deeper territory. Since that 
time, operators have shown a marked preference for the 
steel structures and the numbers of wooden rigs and 
derricks used have been continually diminishing. 

Steel derricks have the advantage of better design, 
better to resist all of the stresses to which they are sub- 




FiG. 18 A. Modern steel derrick of the type used in the California 
fields for deep drilling by the rotary method. (Courtesy of 
National Supply Co.) 

tions. In an effort to secure this advantage in the use 
of cable-drilling equipment, San Joaquin Valley opera- 
tors devised the "standard circulating" system of drill- 
ing. In this method, excavation of the well was accom- 
plished with cable tools, but instead of bailing out the 
drill cuttings, they were brought to the surface by 
means of a circulating fluid pumped down through a 
column of casing, returning to the surface through the 
annular space between the casing and the walls of the 
well. Suspended from a massive swinging spider at the 
level of the derrick floor, the casing was slowly raised and 
lowered to assist in keeping it free of the walls of the 
well. Thorough tests of the method showed it to be 
entirely practical, and it was found possible to drill 
wells through soft, caving formations to depths as great 
as 4,000 ft., using fewer strings of casing than would be 
necessary with the ordinary cable method. Yet, as the 
rotary method developed and found more sympathetic 
reception among San Joaquin Valley operators, it was 
realized that the standard circulating system possessed 
no real advantages over the rotary method, and that 
the latter was cheaper, faster and utilized less cumber- 
some equipment. As a result, the standard circulating 
system soon became obsolete (Lombardi, M. E. 16). 




Fig. 18 B. Hoisting gear and rotary swivel suspended in the der- 
rick. (Courtesy of National Supply Co.) 



46 



Exploration 



[Chap. II 




Fig. 19. Interior view of rig. Modern draw -works and rotary table equipped with under-floor drive. (Courtesy of National Supply Co.) 



jected in service. The material is more uniform and 
dependable in its properties than timber. They are 
lighter and present less surface to the wind. They are 
not so easily distorted under stress. Steel derricks have 
a longer life than timber derricks and present less 
fire hazard. They have a greater salvage value and-are 
readily disassembled and erected at a new location. 
Steel foundation members are more rigid than timber 
foundations. Steel rig wheels maintain their original 
form better than wooden wheels and are mechanically 
more efficient. Concrete foundation piers, generally 
used in supporting steel structures, provide a firmer 
support for the derrick and drilling equipment than 
timber (Uren, L. C. 34, pp. 126-142). 

Steel derricks may be constructed either of structural 
steel forms or of tubular forms, but in the California 
fields, the structural steel type has been most used. They 
have been rigidly standardized as to dimensions and 
essential features by the American Petroleum Institute 
and are available from California and eastern manufac- 
turers in size up to 175 ft, in height and 32 ft. square at 
the base. Constructed of steel of high-tensile strength 
and suitably reinforced, they are designed for safe work- 
ing loads as great as 500 tons with a safety factor of two. 



ROTARY CORING EQUIPMENT 

As previously explained, one of the principal criti- 
cisms of the early rotary drilling equipment was that the 
finely pulverized drill cuttings brought to the surface by 
the circulating fluid did not afford a satisfactory basis for 
determining the character of the formation in which 
the drill was working. Seeking to overcome this diffi- 
culty, rotary core barrels were devised to secure undis- 
turbed samples from the formation in the bottom of the 
well. Early core barrels were of primitive construction, 
designed merely to punch out a short section of the for- 
mation, usually but a few inches long. Such samples 
were often badly "burned" and distorted. Eventually, 
the double-tube core barrel was developed and perfected. 
Equipped with a suitable cutting head attached to the 
lower end of the drill pipe in place of the usual drilling 
tool, these improved core barrels are capable of securing 
cores of the formation penetrated by the well that are 
often as much as ten feet long and but little disturbed. 
They afford very satisfactory samples for all practical 
purposes, though in unconsolidated and semiconsolidated 
formations, they seldom secure more than 75% of the 
interval cored. The remainder, usually the softer strata, 
are disintegrated by operation of the cutting tool. Cores 
ranging from 2 to 5 inches in diameter are common. 






Development of Engineering Techniqu e — U r e n 



47 



Application of early patterns of core barrels required 
reaming of the well to enlarge the cored interval to full 
gauge, but more recent types maintain the full gauge of 
the hole as the core is cut (Uren, L. C. 34, pp. 262-268). 

One reason why core barrels are not more generously 
used is the interruption in drilling progress and conse- 
quent lost time and expense in making two round-trips 
in and out of the well with the drill pipe to substitute 
the coring tool for the ordinary drilling bit, to cut the 
core and bring it to the surface. This may be avoided 
by use of a retractable core barrel that can be run to 
bottom on a wire line through the drill pipe. A special 
type drill is used with the central portion cut away and 
equipped with a locking device for engaging the core 
barrel while the core is being cut. The core barrel and 
core may then be retrieved and removed on a wire line 
through the drill pipe ; or the drill pipe may be removed, 
bringing the core barrel and core to the surface. In this 
case, a core may be cut just before it is planned to remove 
the drill pipe to replace the drilling bit. Though some- 
what smaller than cores cut by ordinary core barrels, 
they are satisfactory for most purposes. 

Most operators now use mechanical coring but spar- 
ingly, particularly in testing formations for landing 
casing and in securing occasional samples of reservoir 
rocks. On the other hand, there are many instances 
where an accurate log is desired — as in the drilling of 
wildcat wells — in which hundreds of feet of formation 
have been continuously cored. A core is often taken to 
determine whether a prospective oil-producing sand is 
oil-saturated or "wet." The presence of oil in a core is 
often clearly apparent, but if there is little oil, a chloro- 
form, ether, or acetone test may be necessary to deter- 
mine whether or not oil is present. Presence of gas in 
a core is usually made apparent by "bleeding" or by 
frothing and expulsion of fluids from the pore spaces of 
the core as it is removed from the core barrel. 

IMPROVEMENTS IN ROTARY DRILLING BITS 

Early drilling with the rotary equipment was accomp- 
lished almost entirely with the fish-tail type of bit. This 
bit served satisfactorily in drilling shallow wells in soft 
formations, but as deeper drilling became necessary and 
harder formations were encountered, it became increas- 
ingly necessary to develop bits that were capable of 
drilling harder rocks and of achieving greater footages, 
requiring less frequent withdrawal of the drill pipe from 
the wells to change bits. For attaining greater footages 
in soft and moderately hard formations, disc bits were 
found useful, first in two-disc patterns, later styles being 
equipped with four discs and side reamers, in some cases 
with the edges of the bits "marcelled." For drilling in 
hard rock formations, fish-tail and disc bits are dulled 
rapidly and "rock bits" equipped with toothed cones or 
rollers are much more effective. Roller core bits are 
available for hard-rock coring. Special types of demount- 
able bits are also effective in moderately hard formations. 
The Zublin bit, affording an unusual eccentric motion, 
has been popular in some California fields. Collapsible 
bits, permitting replacement of the cutting elements 
without withdrawing the drill pipe have found but 
limited use as yet. 

Early bits were made of tool steel ; later, special alloy 
steels were used, particularly chrome steel. Studies of 




Fig. 20. Examples of modern rotary core barrels. 

A. Hughes core bit equipped with hard formation cutter 

head. (Courtesy of Hughes Tool Co.) 

B. Elliott rotary core drill. (Courtesy of Elliott Core 

Barrel Co.) 



48 



Exploration 



[Chap. II 



bit performance soon led to the use of special methods of 
heat treatment designed to develop properties of hard- 
ness and toughness assuring greater footage. Later, 
hard-facing rretals were applied to the corners, edges and 
wearing faces, giving still better performance. And 
finally, tungsten carbide and related alloys of unusual 
hardness were perfected and applied to drilling bits as 
inserts and in powder form. Greatly improved perform- 
ance followed this development. As a result of improved 
bit metals and use of super-hard alloys as facing mate- 
rials, modern rotary bits are capable of achieving foot- 
ages five times those of earlv and more primitive tvpes 
(Uren, L. C. 34, pp. 208-212). 

BIT-PRESSURE CONTROL DEVICES 

Rotary drillers early appreciated the importance of 
maintaining a suitable pressure on the bit during drill- 
ing operations. This was regulated by suspending a 
suitable part of the weight of the drill pipe from the 
crown block on the hoisting cable. The adjustment of 
bit pressure was left entirely to the skill of the driller, 
based upon his observation of mechanical performance 
of the surface equipment. Often excessive pressure 
was allowed to fall on the bit, resulting in twist-off of 
the drill pipe or deflection of the well from the vertical. 
Twist-offs were a frequent cause of interruption in the 
early use of the rotary method, often leading to pro- 
longed and expensive fishing jobs. That excessive bit 
pressure was also a cause of deflection of wells from 
the vertical was not appreciated fully until means were 
devised for surveying wells. 

With the purpose of controlling bit pressure and 
relieving the driller, to some extent, of the responsibility 
of regulating the rate of feeding, a number of mechani- 
cal and hydraulic devices have been developed. The 
first of these was the Hild Drive which, by means of 
electrical controls and differential gearing, automatically 
regulates bit pressure to any desired value that may be 
considered suitable for the particular formation being 
drilled. Later-developed devices of a mechanical nature, 
designed for the same purpose, were the Halliburton 
Drilling Control, the Drillometer, and the General 
Electric Automatic Control using an auxiliary hoist. 
The Brantly Drilling Control, like the others that have 
been mentioned, is designed to regulate bit pressure and 
the rate of feeding, but unlike the others, utilizes 
hydraulic force rather than mechanical and electrical 
gear-driven devices. All of these controls received their 
first trial in the California fields (Uren, L. C. 34, pp. 
220-222, 245-249). 

Another device that has become almost a universal 
part of the rotary drilling rig is the Martin-Decker 
Weight Indicator. This device indicates but does not 
regulate the pressure on the bit. In effect, it registers 
the tension in the hoisting cable which, with proper 
allowance for the number of lines strung between the 
hoisting block and the crown block, is a measure of the 
weight of drill pipe supported by the surface equipment. 
The difference between this and the sum of the weights 
of the drill pipe, drill collar, bit, kelly, swivel and hoist- 
ing blocks, is the pressure on the bit. The weight indi- 
cator not only indicates but may also continuously record 
the tension in the hoisting cable (Uren, L. C. 34, pp. 
220-222, 245-249). 



HYDRAULICALLY CONTROLLED ROTARY EQUIPMENT 
A notable development has been the perfection of a 
type of rotary drilling equipment in which the weight of 
the drill pipe in the well during drilling operations is 
supported by massive hydraulic jacks under the rotary 
table rather than by the hoisting gear and derrick. 
This principle, utilized in earlier types of diamond drills, 
has found expression in an entirely new type of rotary j 
table in the so-called "Hydril" equipment. In addi- 
tion to freeing the hoisting gear and derrick of the duty 
of supporting the drill pipe during drilling, the 
hydraulically supported rotary table permits more sensi- 
tive control of bit pressure than is possible by the ordi- 
nary type of rotary equipment. As a result, it is claimed I 
that holes are straighter and there are fewer twist-offs 
of the drill pipe. The hydraulic equipment is also well , 
adapted to "pressure drilling," a new technique dis- i 
cussed in a later section, and to conditions where high- j 
pressure gas- or water-bearing formations must be pene- 
trated in drilling (Uren, L. C. 34, pp. 254-259). 

DEVELOPMENT OF LONG, HEAVY DRILL COLLARS 

The drill collar was, until recently, but a few feet 
long. Its function was merely to connect securely the 
drilling bit to the lower end of the long column of drill 
pipe. Lately, much longer and heavier drill collars 
have been used, with the purpose of concentrating a 
sufficient mass of metal immediately above the bit to pro- 
duce the requisite bit pressure, thus relieving the drill 
pipe of this function. When the drill pipe furnishes the 
bit pressure, the lower portion of it functions as a col- 
umn under compression. As a result, deflection occurs 
and bending stresses are developed that are largely 
responsible for "twist-offs." When the necessary 
weight is concentrated in the drill collar, practically all 
of the drill pipe may be in tension instead of compres- 
sion and twist-offs are much less frequent. 

DEVELOPMENT OF RAPID ROTATIONAL SPEEDS 

Earlier practice in rotary drilling was conducted 
with table speeds of from 50 to 150 revolutions per 
minute. More recently, in deeper drilling, it has been 
found advantageous to use rotational speeds as great 
as 450 revolutions per minute. By so doing, better prog- 
ress is made in hard formations and, in conjunction with 
long drill collars, fewer twist-offs of the drill pipe occur. 

IMPROVEMENT IN DRILL PIPE STRENGTH AND DESIGN 

Such rapid rotational speed and such deep holes as 
are now drilled, would have been impossible with the 
drill pipe used a decade ago. Today, steel of much 
greater strength is used in drill pipe manufacture. 
Seamless tubing or electrically welded high-carbon or 
alloy steels are now used for this purpose. Better 
design of threaded joints gives greater security. Tool 
joints now used are so designed that they offer less 
resistance to flow of the drilling fluid than formerly. 
The drill pipe is now fitted with rubber "protectors" 
which reduce abrasive friction between the drill pipe 
and the inner wall of the well or the well casing. The 
results are longer life of the drill pipe and less damage 
to the casing (Uren, L. C. 34, pp. 205-208, 223-227). 

IMPROVEMENT IN DRILLING FLUIDS USED IN 
ROTARY DRILLING 

The great depth and rapid rate of progress attained 
today in drilling by the rotary method, would have been 



Development op Engineering Techniqu e — U een 



49 




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50 



Exploration 



[Chap. II 



impossible without the improvements in drilling- fluid 
preparation and conditioning that have been achieved in 
recent years. Originally, any clay found near the well 
was mixed with water to form the drilling fluid ; or, drill 
cuttings from the clay and shale beds encountered in the 
well, on hydration, were considered to be an adequate 
source of clay. Today it is recognized that the properties 
necessary in a satisfactory drilling fluid are secured only 
by using carefully selected clay having special character- 
istics. Often a suitable clay is not found near at hand, 
but must be transported to the well over distances of 
many miles, at great expense. Freedom from sand and 
abrasives and well-developed colloidal properties are con- 
sidered important in the clay used. 

When the clay is thoroughly hydra ted and suspended 
in water, the resulting drilling fluid must have a suitable 
density, viscosity and shear value. The colloidal proper- 
ties, as indicated by the hydrogen ionization value, must 
be high. It must show a tendency to "gel" on standing 
at rest for a short time. The drilling fluid has a variety 
of functions to perform, some of which require the special 
development of certain properties. For efficiently lifting 
drill cuttings, the fluid must have proper density, vis- 
cosity and shear value. To form rapidly a sheath of clay 
on the walls of the well and seal off porous formations, 
it must have high viscosity and well-developed colloidal 
properties. To prevent blow-outs of high pressure gas 
encountered in the well, it should have high density and 
low viscosity. 

Special properties are at times quickly developed in 
the drilling fluid by adding other materials. Finely 
ground bentonite marketed under the name of "Aqua- 
gel" develops high colloidal values. Finely ground 
barite, marketed under the name of ' ' Baroid ' ' and finely 
divided iron oxide, called "Colox, " are added to increase 
the density of drilling fluids. Some chemical reagents, 
such as tannic acid ("Quebracho") or sodium silicate 
("water glass"), increase the viscosity of clay-laden 
fluids, while sodium phosphate has the reverse effect. 

Drilling fluids are ordinarily prepared at the indi- 
vidual wells, though in some fields they are prepared in 
community plants and delivered by pipe line or tank 
truck to the wells. Costs are likely to be lower in com- 
munity plants and the product more uniform and de- 
pendable. Costs range from l(ty to 50^ per barrel of 
fluid, averaging perhaps $3,000 per well during recent 
years in the California fields. In one instance, the drill- 
ing fluid cost was as high as $50,000. As a measure of 
economy, some operators have given special attention to 
the problems of reconditioning drilling fluid for con- 
tinued use. Such reconditioning involves separation of 
fine sand that may tend to remain afloat in the fluid, 
removal of entrained gas and restoration of proper 
density and viscosity after dilution or contamination 
during circulation through the wells. For removal of 
sand and gas in suspension, vibrating screens are widely 
used. Another method involves first diluting the fluid to 
promote settling of sand and then thickening to restore 
the fluid to its proper density and viscositv (Uren, L. C. 
34, 227-236). 

IMPROVED AND LARGER CAPACITY POWER PLANTS 

Early cable-tool and rotary equipment was almost 
universally powered with steam boilers and engines and, 



because of its greater flexibility, most drillers had a 
decided preference for steam power over other prime 
movers. Steam power is still preferred, and a large per- 
centage of the drilling rigs used during recent years 
were equipped with steam engines and direct-acting 
steam-driven pumps. Nevertheless, other types of power 
are finding increasing favor and may in future find 
wider use. Electric motors of special design have been 
found entirely satisfactory for rotary drilling, and eco- 
nomic where cheap utility service is available. Provision 
of expensive boilers and incidental steam equipment is 
avoided, as well as expense in development of a supply 
of water in quantities and of a quality suitable for steam 
generation. Internal combustion engines also share these 
advantages with the electric motor, it being only neces- 
sary to provide a supply of water for jacket-cooling pur- 
poses, and this need not be of the purity required for 
steam generation. Gas engines and Diesel and semi- 
Diesel engines operating on various grades of Diesel and 
fuel oils or crude are used for drilling purposes. Though 
somewhat less flexible than steam power, with proper 
intermediate gearing and transmission mechanism, they 
afford an entirely satisfactory source of power for drill- 
ing purposes. Some wells have been powered with 
Diesel-electric drives, the Diesel engine serving as a 
.source of power which is applied through the somewhat 
more flexible electric motor. Internal combustion engines 




Fig. 22. Power plant for modern rotary drilling rig. 



Development op Engineering Techniqu e — U r e n 



51 




Fig. 23. Well-cementing equipment permanently mounted on motor truck. (Courtesy : Perkins Cementing Co.) 



are well adapted to conditions presented in drilling ' ' wild- 
cat" wells in areas remote from gas fuel supply. Both 
single-cylinder and multi-cylinder types have been 
adapted but the latter seem preferable. They are effi- 
cient from a power development standpoint and they may 
operate on liquid fuel which can be delivered by truck or 
tractor to the well. In some districts, gas engines using 
liquefied butane as a fuel provide a satisfactory solution 
for the power problem. 

Many different "hook-ups" are employed in connect- 
ing the several parts of the rotary drilling rig with the 
power supply. If steam power is employed, the hori- 
zontal twin-cylinder engine generally used to drive the 
draw works and rotary table, is usually connected with 
the line-shaft of the draw works by a chain-and-sprocket 
drive. Different chain-and-sprocket drives between the 
line-shaft and drum-shaft, with suitable clutch controls, 
afford three speeds for the drum-shaft. If additional 
flexibility is desired, it may be achieved by interposing 
an assemblage of speed-reduction gears between the 
engine and draw works, thus providing as many as six 
drum-shaft speeds. Originally, the rotary table was 
driven by a chain-and-sprocket drive from the line-shaft 
of the draw works. In the more modern three-shaft 
draw works, the table is driven from the jack-shaft of the 
draw works. Some operators now provide a separate, 
smaller engine to drive the rotary table, this engine often 
being placed below the derrick floor. Preference has 
been shown by some drillers for vertical steam engines, 
which are available in either twin-cylinder or three- 
cylinder patterns. If internal combustion engines are 
used, one large unit operating singly, or two smaller units 
"hooked" together to operate simultaneously, may be 
used to drive the draw works and table. Electric motors 
may similarly be applied. 

When steam power is used, modern practice gives 
special attention to economy and efficiency of operation. 



Preheaters for the boiler water and super-heaters for the 
steam are now frequently employed, though formerly 
almost unknown in oil-field practice. Boiler settings 
and steam mains are now well insulated. Fuel and feed- 
water pumps are automatically controlled and many 
safety features are incorporated that enable the boiler 
plant to operate with less manual supervision than was 
formerly necessary. In earlier periods, little attention 
was given to such refinements. Natural gas, produced 
in great quantities with the oil in many fields, was a 
waste product. Used as a boiler fuel and costing little 
or nothing, there was no incentive to seek efficiency in 
power development. Today, however, there is a profit- 
able market for natural gas in most California fields ; 
or the gas may be stored and put to economic use by 
reinjeetion in the reservoir rocks to assist in producing 
additional oil. Under these conditions, there is every 
incentive for economy in gas consumption and operators 
are finding profitable the refinements necessary to secure 
greater efficiency in steam development and transmis- 
sion (Uren, L. C. 34, pp. 236-244). 

LARGER CAPACITY AND HIGHER PRESSURE 
CIRCULATING PUMPS 

Early types of mud pumps used in rotary drilling 
were designed for capacities of less than 100 gallons per 
minute and for low pressures. Steam ends were often 
designed for steam pressures of 150 lb. per sq. in. and 
water ends for pressures not exceeding 300 lb. With 
deeper drilling has come the necessity for much heavier 
and larger capacity pumps, some models recently 
employed having a capacity as great as 1.450 gal. per 
minute, with 500 lb. steam pressure and with water ends 
designed for delivery pressures as great as 3,750 lb. per 
sq. in. For the same size hole and drill pipe, circulating 
pressures increase directly with depth. Modern cement- 
ing operations also place an increasing burden on the 
pumps. So large have the pumps become, that they are 



52 



Exploration 



[Chap. TI 



now generally placed outside the rig rather than on 
the derrick floor, as formerly. Elevation of the derrick 
floor, several feet above the prevailing level of the 
ground, permits the placing of pumps on a lower level, 
reducing the suction lift of the pumps and increasing 
their operating efficiency. For use with rigs powered 
with electric motors or internal combustion engines, 
pumps driven by belt or rope drives are customarily 
used. 

TREND TOWARD UNITARY CONSTRUCTION OF 
DRILLING EQUIPMENT 

In earlier periods, it was usual to spend from two 
to three weeks in preparing the site, erecting a derrick 
and "rigging up" in preparation for the drilling of a 
new well. This was because of the multiplicity of parts 
and because of the necessity of framing much of the rig 
timber in the field. Today, steel derricks are pre- 
fabricated and, with a .skilled crew of rig builders, can 
be erected in a day or two. Within the last few years 
also, important progress has been made in unitary con- 
struction of the mechanical elements of rotary drilling 
rigs, so that they too may be quickly assembled. Draw- 
works are now often mounted on steel A-frames and 
supports so that all parts are permanently assembled 
and adjusted by the manufacturer and moved into the 
field and from rig to rig as a unit. The rotary table, 
the mud pumps, and power plant are frequently also 
mounted with their assembled parts, on their own indi- 
vidual steel skids, so that they can l>e moved from one 
location to another without necessity for disassembling. 
Under favorable conditions, even complete derricks, once 
assembled in the field, can be "skidded" from one loca- 
tion to another without tearing down. The result has 
been that equipment may now be brought into the field, 
set up in operating position and all made ready for 
"spudding" in less than half the time formerly neces- 
sary. Not only is time saved, but the equipment has 
higher salvage value and can be used in the drilling of a 
greater number of wells. 

STAND-BY EQUIPMENT 

Modern rotary rigs are frequently equipped with a 
power-driven sand reel to assist in bailing operations, 
running retractable core barrels and drilling bits and 
like purposes. For deep drilling, larger stand-by hoist- 
ing drums are also frequently provided to assist in 
handling drill pipe. In drilling very deep wells, a 
third slush pump is provided in addition to the custom- 
ary two. These features were unknown in the earlier 
types of rotary rigs. 

GREATER UTILITY OF PORTABLE RIGS 

Portable and semi-portable drilling rigs have been 
used for many years in drilling shallow wells by the 
cable-tool method. Some of the heavier patterns of port- 
able churn-drilling rigs are capable of drilling to depths 
as jrreat as 4,000 ft. In recent years, considerable 
advance has been made in the development of rotary 
portable equipment capable of drilling to comparable 
depths. The draw works and rotary machine are 
mounted on one truck, tractor, or trailer, and the circu- 
lating pumps on another. A braced mast provides over- 
head gear for handling drill pipe and casing. Light 
portable rigs of both churn and rotary types are now 



commonly employed for structure drilling and for drill- 
ing shot holes in seismic exploration. 

TREND TOWARD DEEPER DRILLING 

With the exhaustion of the shallower accumulations j 
of petroleum, operators have been compelled to seek 
deeper sources of supply. Improved drilling equipment 
and methods have made deeper drilling less expensive 
than formerly, and have thus brought the deep-seated 
deposits within the realm of economic exploitation. The 
higher formation pressures and greater quantities of 
dissolved gas in the oil, characteristic of the deeper 
deposits, often result in very prolific wells, so that while 
deep wells are costly to drill, yet they may quickly repay 
their cost if not too closely spaced and if allowed to pro- 
duce without undue proration restriction. 

In 1910, wells in excess of 3.000-ft, depth were 
uncommon. By 1920, with the widespread use of rotary 
equipment, depths in excess of 6,000 ft. were being suc- 
cessfully drilled, and by 1930, a depth of 8,500 ft. had 
been attained. During the last decade, new drilling 
depth records have frequently been achieved, reaching 
12,500 ft. in 1935 and 15,000 ft. in 1938. The maximum 
depth to which it would be possible to drill with present- 
day equipment and methods, is a matter of conjecture, ; 
but some authorities believe that 20,000-ft. wells are not 
impossible under present-day conditions. 

IMPROVEMENT IN MATERIALS EMPLOYED IN MANU 

FACTURE OF DRILLING EQUIPMENT AND 

WELL EQUIPMENT 



d 



No small part of the superior performance an 
greater strength of modern rotary equipment is due to 
the use of materials especially selected for the heavy 
duty imposed. For example, electric cast steel and 
manganese steel drive sprockets, chrome steel forged 
and heat-treated shafts, steel castings, rolled and forged 
alloy steel brake rims and manganese steel clutches and 
cat heads are used in most of the heavier and costlier 
draw works. Crown block and hoisting block sheaves 
and shafts, casing hooks, swivel gudgeons and bails, 
casing and drill pipe elevators, rotary table bearings and 
raceways and other structural details have received care- 
ful study from the design standpoint and the best 
materials obtainable used in their manufacture. Use 
of high tensile strength steels has also been extended to 
materials used in derrick construction and in casing 
manufacture. Use of tungsten carbide and other hard- 
facing metals on drilling bits has been previously men- 
tioned. 

LARGER AND HEAVIER EQUIPMENT FOR 
DEEPER DRILLING 

The present record depth of about 15,000 ft. for 
rotary-drilled wells in California, would have been quite 
impossible with the drilling equipment of ten years ago. 
The ever-increasing depth to which wells have been 
drilled during recent years, has required the development 
of larger and heavier equipment, better correlation of 
equipment, stronger materials and superior workman- 
ship. Manufacturers of drilling equipment have been 
largely responsible for this advance. 

The larger and heavier rotary rigs that have lately 
been used in drilling in the deeper fields of the southern 
San Joaquin Valley, have utilized the most advanced and 



Development of Engineering Techniqu e — U een 



53 



most highly developed equipment that has yet been made 
available for drilling purposes. Equipment employed in 
the so-called "super rig;" used by the Superior Oil Com- 
pany may serve as an example of forward-looking plan- 
ning for even deeper drilling than any yet attempted. 
In this rig, the derrick used was 178 ft. high and 32 ft. 
square at the base, constructed of high tensile strength 
structural steel and designed for a safe working load 
capacity of 500 tons. The rig was powered with five 
130-h.p. steam boilers of locomotive type, developing 
500-lb. steam pressure and capable of delivering 3,000 
boiler horse-power for a short period of time. Super- 
heaters heat the steam to 610° F. The draw works was 
driven by a 15-in. by 14-in. twin-cylinder steam engine, 
rated at 1,950 h.p. at 250 r.p.m. with 500-lb. steam pres- 
sure. A separate twin-cylinder engine, 12-in. by 12-in. 
in size, placed beneath the derrick floor was used to oper- 
ate the 20^-in. rotary table. A three-speed draw works 
with 10^-in. drum-shaft, 9-in. line-shaft and a drum 
capacity of 4,690 ft. of 1^-in. hoisting cable, and equipped 
with a 40-in. double-rotor type Parkersburg Hydromatic 
brake, was used. The two mud pumps were 15^-in. by 
9^-in. by 22-in. steam-driven pumps, designed for a maxi- 
mum pressure of 3,750 lb. per sq. in. and capable of 
delivering 1,450 gal. per minute. The swivel and hoist- 
ing gear were designed for a maximum drill-pipe load of 
300 tons. The swivel hose is of steel, 5 inches in diame- 
ter, and designed for fluid pressures as high as 6,000 lb. 
per sq. in. 

With this equipment, under the conditions presented 
in the Rio Bravo field, Kern County. California, in one 
well, 7,000 ft. of 12^-in. hole were drilled in eight days. 
Total elapsed time from spudding date to completion at 
11,445 ft., was only 57 days and this included the time 
spent in inserting and cementing casing and inserting 
the liner and tubing (Sawdon, W. A. 39). Another well, 
drilled by the Union Oil Company of California in the 
Rio Bravo field, was drilled to a depth of 11,415 ft. in 
only 46 days, including the setting of 1,515 ft. of 13f-in. 
casing and 11,166 ft. of 7f-in. casing and 5f-in. liner. 

IMPROVEMENT IN TRANSPORTATION FACILITIES 

Many tons of mechanical equipment, drill pipe and 
casing, cement and drilling-fluid components and rig 
and derrick materials, must be transported to the site 
selected for a well. In drilling "wild-cat" wells, fuel 
and perhaps even water may have to be hauled to the 
well. Some parts of the equipment such as steam boilers, 
are not only heavy but also bulky. Suitable facilities for 
transport are therefore of vital importance. Because of 
generally favorable climatic conditions and gently slop- 
ing, open terrain and accessibility to sources of supply, 
transportation into the oil fields of California has never 
been as difficult a problem as in most other oil-producing 
regions. Nevertheless, delivery of materials and equip- 
ment has been greatly facilitated during the last two or 
three decades by the development of California's excel- 
lent highway system and by modern types of motor 
trucks, trailers and tractors especially adapted to the 
handling of oil-field equipment. Much of the machinery 
and equipment is manufactured in communities within 
a few hundred miles of the oil fields and is moved 
directly to the point of use by motor truck. Stocks are 
maintained by manufacturers of practically all oil-field 



supplies and equipment in warehouses near the impor- 
tant centers of oil industry activity. 

IMPROVEMENTS IN WELL CASING AND 
CASING PRACTICE 

All wells must be cased to prevent caving of the walls, 
to confine high pressure fluids, and to exclude water from 
oil and gas bearing formations. Great quantities of 
casing are used in the development of California oil and 
gas fields ; in many instances, as much as one-third of the 
total cost of drilling and completing wells is represented 
by this item. 

Formerly, the casing used was manufactured by lap- 
welding and was available in many different sizes and 
weights. The material used was either wrought iron or 
mild steel. One of the first efforts of the American 
Petroleum Institute following its organization, was to 
standardize well casing sizes, weights, materials, and 
threaded connections. As a result, the industry is now 
served with fewer sizes of casing, and the materials used 
have more dependable properties. In casing the deeper 
wells, stronger steel than that formerly used must be 
employed. Whereas the mild steel formerly employed 
possessed a tensile strength of only 55,000 lb. per sq. in., 
the stronger grades of high- carbon steel used today 
develop tensile strengths as great as 110,000 lb. per sq. 
in. Where still greater strength and ductility is needed 
than can be secured with ordinary steels, casings made of 
special grades of alloy steel are available. Single strings 
of large-diameter pipe as much as 13,000 ft. long and 
weighing more than 200 tons have been placed in some 
of the deeper wells drilled in the southern San Joaquin 
Valley. 

Modern casing practice involves careful selection of 
sizes, weights, and lengths of individual strings, with due 
regard to the purposes that they must serve and the 
stresses which they may be called upon to sustain. 
Where fluid accumulates to depths of thousands of feet 
behind a column of casing cemented to the formation at 
its lower end, very great collapsing pressure is developed : 
sometimes so great as to result in failure. Casing or 
threaded casing joints are sometimes pulled apart by 
excessive tensile stress developed in pulling on columns 
of pipe frozen to the walls of wells. The "pull-out 
strength" of threaded joints is a matter of importance 
in this connection and can be increased by proper design 
of threads and collars. Casing may buckle as a result of 
"column action" when allowed to rest on the bottom of 
the well. Casing and casing heads are sometimes sub- 
jected to large bursting pressures when high-pressure 
gas must be confined. 

In addition to ordinary collared-joint casing, special 
types of inserted-joint and flush-jointed casings are now 
available for use under circumstances such that collars 
would be disadvantageous. Long columns of casing are 
at times formed of joints welded together without collars 
of any kind. The old style of "stove-pipe" made of 
thin sheet-metal with riveted joints, is now rarely used. 
Instead, surface and conductor strings of large diameter 
casing are often of corrugated form or, are of thin-walled 
rolled steel, equipped with bell-and-socket joints, held 
together by spot-welding (Uren, L. C. 34, Chapt. VIII). 

The lowermost string of casing in the well, extending 
through the oil-producing formation, is customarily per- 



54 



Exploration 



[Chap. II 



fOi-ated to admit fluids from the formation. The per- 
forated sections are made up of screen pipe, available in 
a variety of forms. The older types of wire-wrapped 
screen pipe, though still widely used in some regions, are 
today little used in the California fields. Most California 
operators prefer a slotted pipe in which narrow longi- 
tudinal slots disposed in several rows about the pipe cir- 
cumference, are cut by the oxyacetylene torch. Two 
types of "button screen pipe" are also used, in which 
round holes are fitted with bronze or brass discs contain- 
ing slot-shaped openings. Gun-perforating devices, de- 
veloped during recent years, are now used for shooting 
pointed steel bullets through casing in wells. By this 
means, blank pipe may be perforated opposite any 
desired interval, after placement in the well. The gun 
perforator has also been a useful device in connection 
with certain types of cementing operations. A type of 
cement-lined perforated casing has been found helpful 
under conditions that required circulation of fluid 
through the casing after it is in place in the well. After 
circulation, the perforations are opened by "scabbing- 
off " the thin cement lining. Recently, use has been made 
of magnesium alloys in manufacture of short sections of 
casing, for use under circumstances that require the 
casing to be dissolved by acid subsequent to placement. 

WATER EXCLUSION PRACTICES 

Efficient production of petroleum requires exclusion 
of water from that portion of the well that yields the oil. 
If both oil-bearing and water-bearing formations have 
access to the well, it will produce mostly or entirely 
water ; and the water may force its way into the oil-bear- 
ing strata, driving the oil away from the well and water- 
logging the wall rocks so that they may never produce 
oil in commercial amounts. Underground losses of oil 
resulting from failure to exclude water from wells and 
from the oil-bearing formations were serious during the 
earlier period of oil production in California, but were 
eventually recognized by producers as of suffiicent im- 
portance to justify conservation legislation and regula- 
tion of well drilling and producing operations by the 
State. In accordance with this legislation, the California 
State Mining Bureau was charged with the responsibility 
of prescribing appropriate measures for exclusion of 
water in oil-field exploitation, and a State Oil and Gas 
Supervisor was appointed to administer the law and 
make field studies and tests on all drilling wells to ascer- 
tain that the California oil fields were adequately pro- 
tected against water incursion. The Oil and Gas Super- 
visor's department, which has been operative since 1914, 
has since been divorced from the State Mining Bureau 
or State Division of Mines, and is now a separate Divi- 
sion of the State Department of Natural Resources and is 
known as the Division of Oil and Gas. The Supervisor 
maintains headquarters in San Francisco, and field offices 
conveniently situated with respect to the active oil- 
producing areas. A staff of engineers and inspectors 
gather detailed subsurface information concerning every 
oil field in the State. Logs of every well are filed with 
the Supervisor by the operators. Casing programs and 
drilling procedure designed to prevent water incursion 
are prescribed and tests are made to assure that water 
is properly excluded from every well drilled. Reports 
on quantities of oil, gas, and water produced by each 



well are furnished monthly by the operators to the Oil 
and Gas Supervisor's department, which thus maintains 
a continuous record of the entire productive history of 
each well drilled and operated. On the basis of such 
production records, the Supervisor may take steps to 
enforce appropriate measures to exclude water from 
wells which may threaten the security of surrounding 
producers. On abandonment, all wells must be suitably 
plugged to prevent the possibility of water subsequently 
entering them and flooding productive od- and gas-bear- 
ing formations. 

Early methods of water exclusion in the California 
oil fields included use of packers, which were manipu- 
lated between the casing and walls of the well, and "for- 
mation shut-offs, " in which the column of casing, 
equipped with a reinforcing shoe on its lower end, was 
driven into an under-sized hole drilled into a hard layer 
of shale or other competent, impermeable stratum. Later, 
cementing methods were introduced, designed to accomp- 
lish the placement of a substantial quantity of fluid 
cement between the walls of the well and the casing, 
where it was permitted to set and harden. In this way, 
the annular space about the lower end of the casing, 
between it and the wall of the well, is completely filled 
with a solid body of impermeable cement that effectively 
excludes top waters from that portion of the well below 
the easing shoe. 

Cement was first placed in the wells with the aid of 
dump bailers. Later, methods were devised for pumping 
fluid cement to the bottom of the well through auxiliary 
tubing specially inserted inside the casing for the pur- 
pose. A packer between the tubing and casing prevented 
the fluid cement from rising in the annular space, thus 
forcing it under the shoe of the. casing and up into the 
space between the casing and the wall of the well. Even- 
tually, the Perkins process for placing cement in wells 
was developed. This involved pumping the fluid cement 
down through the casing between a pair of moving 
wooden plugs that serve to separate the cement from the 
well fluid. After the cement, forced under the shoe of 
the casing and up into the annular space about the pipe 
by the pump pressure, is hardened, the plugs and small 
amount of cement within the lower end of the casing are 
drilled out with the drilling tools. For many years, the 
Perkins Cementing Company, a California service organi- 
zation, has been engaged in cementing operations of this 
character in the California oil fields, contracting cement- 
ing jobs and furnishing skilled personnel and special 
equipment brought to the wells on motor trucks. More 
recently, the Halliburton Well Cementing Company, 
Mid-Continent and Gulf Coast organization, controlling 
a number of patented improvements in well cementing 
technique, has also entered the California industry. 

In addition to the usual methods of cementing casing 
in wells, a variety of more intricate special practices have 
been developed within recent years. For example, a 
rather common practice today is that of cementing 
through perforations. This practice is used when it is 
desired to spot cement at a particular depth in the well 
without forcing it under the shoe of the column of casing 
and cementing a long intermediate interval. Holes are 
punched or shot in the casing at the desired depth, a 
plug is set in the casing immediately below, and fluid 
cement is forced through the perforations under pump 



ig 



Development of Engineering Techniqu e — U R e n 



55 



pressure, into the annular space outside the casing. For 
this and other special procedures, the "cement retainer," 
manufactured by the Baker Oil Tools Co. — a California 
organization — has been found especially helpful. This 
company also manufactures a wide variety of cement 
shoes and collars, baskets, plugs, and other devices espe- 
cially designed to assist in cementing operations. 

Success of a modern well cementing operation may 
involve rapid mixing and placement of a large volume of 
cement. Cement mixers appropriate for this purpose 
have been devised and large-capacity high-pressure 
pumps for handling the cement-water mixture, while 
special cementing heads are available to facilitate rapid 
connection with the easing head. As much as 2,500 sacks 
or 237,500 lb. of cement have been mixed with the proper 
proportion of water and pumped into place at the bottom 
of a well 11,520 ft. deep, in only 54 minutes. Portland 
cement usually takes its initial set in from one to two 
hours and it is imperative that the cement be at rest in 
the position it is to occupy in the well before the initial 
set occurs. The "hardening set" is a slower process, 
ordinarily requiring from 7 to 28 days. Formerly it was 
necessary to allow a well to stand after a cementing job 
for this period of time, but the use of a small amount of 
a suitable accelerator, such as calcium chloride, hastens 
the hardening set so that the cement may be drilled out 
of the casing and deeper drilling resumed after only 
three or four days of setting. To save time, accelerators 
in the cement are today almost universally used. 

Difficulties sometimes develop in cementing opera- 
tions, perhaps occasioning failure and repetition of the 
work. Dilution of the fluid cement with ground water 
containing certain dissolved salts may alter the setting 
properties, delaying or hastening the setting time and 
perhaps rendering the cement "unsound." Unusually 
high ground temperature encountered especially in deep 
wells, greatly hastens the setting time. Contamination 
with mud or clay in the well weakens the cement. 
Natural gas blowing through the fluid cement iu the 
well leaves it porous and permeable and may prevent it 
from setting property. The cement sometimes does not 
distribute itself uniformly about the casing, leaving 
channels through which water may subsequently find 
its way. Successful handling of cementing operations 
is secured only by careful engineering supervision and 
by employing skilled personnel in the work (Uren, L. C. 
34, Chapt. X). 

LOCATING SOURCES OF WATER INCURSION IN WELLS 

Before water exclusion operations are undertaken, it 
is necessary to determine the exact depth at which the 
water enters the well. For this purpose, special electri- 
cal devices have been developed. Oil-field ground waters 
are often highly saline and one method, utilizing the 
"Water Witch," measures the electrical conductivity of 
the well fluid. The point at which the well fluid reaches 
its highest electrical conductivity is that at which the 
i water enters. In another method, the fluid in the well 
! throughout the interval where water is thought to enter 
! is conditioned by adding an electrolyte that develops 
galvanic activity. Influx of water dilutes the well fluid 
i locally, opposite the point of entry, and exploration 
| with the "Lo-kate-it" device discloses this point. In 
I still another device, a photo-electric cell is utilized (the 
j Dale Water-Locating Instrument). Lowered through 



the drilling fluid in the well, it develops a greater elec- 
trical response at the point where the fluid has been 
locally diluted by infiltration of water from the forma- 
tion. More primitive methods of locating the source 
of water in a well involve plugging the well in stages 
from the bottom up, until the water is eliminated, or 
plugging to a point well above the source of water and 
then drilling out in stages until water again appears. 

WELL SURVEYING EQUIPMENT 

Until about 1920, operators had no convenient and 
dependable means of surveying wells to determine their 
course. It was generally believed that wells drilled by 
either the cable or rotary methods were reasonably 
straight and vertical, but the first dependable survey- 
ing instruments developed indicated that they were 
often crooked and at times departed widely from the 
vertical. This knowledge, and consideration of the 
problems arising therefrom, stimulated interest in the 
subject of well surveying until today many wells are 
surveyed so that their actual course beneath the surface 
can be charted with fair accuracy. 

The pioneer well surveyor of California was Alexan- 
der Anderson, who developed instruments and offered 
the services of his highly skilled personnel to operators 
in the California oil fields. During the period 1920 to 
1937, when it was acquired by the Layne-Wells Com- 
pany, many hundreds of thousands of feet of hole were 
surveyed by the Anderson organization. Other well 
surveying organizations meanwhile entered the Califor- 
nia fields with other types of instruments and with serv- 
ice organizations equipped to undertake surveys on a 
contract basis. Other well known names in this field are 
the Eastman Well Surveying Company and the Sperry- 
Sun Company. 

Instruments used in making well surveys may be 
classified into two groups : first, those which merely 
determine the amount of deflection from the vertical 
(clinographs or inclinometers), and second, those which 
measure both the amount and direction of the deflection 
(directional clinographs). Instruments of the first 
group are comparatively simple. Perhaps the simplest 
and most widely used inclinometer is the hydrofluoric 
acid bottle. The Syfoclinograph and Totco instruments 
are also widely used devices of this group. The direc- 
tion of the deflection may be determined by orienting an 
inclinometer of suitable design into and out of the well 
on drill pipe or tubing. However, some well surveying 
instruments use a series of compass observations to indi- 
cate the course of the hole. Under favorable condi- 
tions, the magnetic compass may be used for this pur- 
pose in open hole, but the Surwel Clinograph utilizes 
a gyroscopic compass as a direction indicator. Direc- 
tional clinographs are either "single-shot" instruments 
or are designed to record continuously or intermittently 
data as they are lowered or raised through the well. 
From these data the deflection and azimuth of the well 
at numerous points may later be computed. Descrip- 
tions of these and many other interesting instruments 
designed and used for this purpose may be found in 
generally available books on petroleum engineering 
(Uren, L. C. 34, pp. 487-499). 

Well surveys have indicated that comparatively few 
wells are straight and vertical, irrespective of the method 
of drilling. In some instances, wells 5,000 to 10,000 ft. 



56 



Exploration 



[Chap. II 



deep have been found to wander many hundreds or 
even thousands of feet laterally from their starting 
points. In many cases, boundary wells have trespassed 
on neighboring properties, securing production from 
acreage not owned or controlled by the owner of the 
well. Where loss has resulted from trespass of this 
character, damages may be claimed and secured by liti- 
gation. Confusion has arisen in some instances through 
efforts to use the logs of crooked holes in geologic corre- 
lations or in structural interpretations, wells appearing 
structurally lower than they should be, by reason of the 
greater footage necessary to reach a particular strati- 
graphic horizon in a crooked hole. On the other hand, 
where wells wander up-dip, they may encounter a par- 
ticular reference horizon at shallower depth than would 
be the case in a vertical hole. In some jurisdictions, 
state authorities restrict the amount that a well may 
deviate from the vertical : for example, 5° deviation 
from the vertical may be the maximum deflection per- 
mitted. Rules of this character become necessary where 
an effort is made to regulate the spacing of wells. 



DIRECTIONAL DRILLING 

Knowledge of the readiness with which wells deviate 
from the vertical, and of the causes therefor, have led 
in some instances to intentional deflection of wells with 
the purpose of reaching objectives not readily attained 
by drilling vertical wells. Control of the drilling con- 
ditions and use of special types of equipment in such a 
way as to promote deflection of wells toward a desired 
objective some distance laterally from their surface loca- 
tions, is called "directional drilling." Well surveying 
instruments are necessarily used in this procedure to 
follow the course of the well and to orient the equipment 
used in producing deflection of the drilling bit. 

Deflection of the well from the vertical may be accom- 
plished at any depth by placing a "whipstock" — a long, 
slender, metal, wedge-shaped tool in the hole and orient- 
ing it so that it will deflect the drilling bit in the desired 
direction. Special eccentric bits may be used, or a 
"knuckle joint" in the drill collar which promotes 
deflection of the well along the course determined by 
the slope of the whipstock. Wells may be drilled at an 




Fio. 24. Map showing- course of a crooked well. (After P. J. Howard) 






Development of Engineering Techniqu e — U ren 



57 



angle from the surface, by slightly elevating one side of 
the rotary table so that it is slightly higher on the side 
toward which the hole is to be deflected. 

Directional drilling has been employed by some oper- 
ators as a means of accomplishing illegal trespass on 
another operator's property. For example, in some 
California fields, wells which, by their structural posi- 
tion, should have encountered edgewater, have been 
deflected up-structure to secure production from areas 
above the edgewater line. In the Huntington Beach 
field of California, a part of the productive area of the 
field lies beneath tidelands along the shore of the Pacific 
Ocean. Littoral owners have in many cases deflected 
wells so that they are bottomed in the tideland area. In 
some instances, the bottoms of wells in this area are as 
much as half a mile from their surface locations. Where 
productive oil sands lie beneath townsites and drilling 
restrictions are imposed, wells may be drilled from loca- 
tions in out-lying tracts beyond the restricted area. 
Wells may be deflected to pass under the overhanging 
edges of salt domes to reach underlying oil accumula- 
tions, rather than drill through the salt core and the 
hard capping overlj-ing it. Wells may be deflected to 
reach oil accumulations in the foot-wall side of a fault 
plane, rather than attempt to drill through the fractured 
and "slickensided" material in the overlying faulted 
zone. In one instance, a well was deflected to encounter 
another well at depth, with the purpose of pumping 
water and mud into the well to extinguish a surface fire 
that had defied other extinguishing methods. By direc- 
tional drilling, it is possible to drill two or more wells 
from one surface location, bottoming them in the pro- 
ductive formation in different areas properly spaced. 
This has been successfully accomplished in drilling from 
steel piers extending off-shore in the Elwood field on the 
Pacific Coast of California. 

IMPROVEMENT IN WELL COMPLETION METHODS 

In the earlier period of exploitation in the California 
oil fields, there were many instances in which high-pres- 
sure wells were "brought-in" out of control. Unexpect- 
edly high gas pressures, or absence of suitable control 
equipment on the well head, often resulted in destruc- 
tive "blow-outs" and wasteful gusher production of oil 
and gas. In the case of the Lakeview No. 1 gusher, 
situated in the Sunset field of Kern Country, control of 
the well was lost after drilling into the producing sand, 
and months passed before the flow of oil and gas could 
be shut in. During this period, it is estimated that ten 
million barrels of oil were discharged at the surface, 
much of which had to be stored in open earthen reser- 
voirs, so that serious evaporation and seepage losses 
occurred. Gusher production was not uncommon during 
the earlier period of the California oil industry when 
wells were drilled with cable tools. 

One of the principal advantages of the rotary method 
of drilling is its ability to control high pressure fluids 
and prevent blow-outs, so that occurrences of this char- 
acter have been less common since the rotary equipment 
has come into general use. Proper control of the circu- 
lating fluid and provision of a suitable blow-out pre- 
venter on the casing head will permit safe drilling into 
a high-pressure formation. Today, wells are completed 
and brought in, and production is turned to the flow 





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Fig. 25. Vertical section showing deflection of a well from the 
vertical. (Courtesy of McGraw-Hill Book Co., Inc.) 

tanks with little or no loss of oil and gas. Indeed, it is 
now regarded as evidence of unskillful drilling tech- 
nique or use of inadequate control equipment if a high- 
pressure well is allowed to get out of control. 

With modern methods of formation testing, coring 
and electrical logging, it is now possible to determine 
the intervals within the formations penetrated by a well 
that are likely to yield oil, gas, or water. The casing 
"string" to be placed in the lower part of the well may 
then be made up at the surface, with perforated pipe 
opposite in the oil and gas yielding intervals and blank 
pipe opposite the water-yielding intervals. Cementing 
these blank sections to the wall of the well through per- 
forations excludes all water; or, an entire column of 
blank liner may be cemented in the lower part of the 
well and gun-perforated in the oil- and gas-yielding inter- 
vals. Recently developed methods of gravel-packing per- 
forated liners in wells involve reaming the productive 
intervals to as large a diameter as is economically feas- 



58 



Exploration 



[Chap. II 



ible and then circulating gravel (£" to Mo") into the 
space between the wall of the well and the exterior sur- 
face of the liner. Gravel so placed prevents caving of 
the walls of the well, prevents sand incursion, and per- 
mits more efficient drainage of oil from the surrounding 
reservoir rock. 

Concern is often expressed by engineers over the 
tendency of clay-laden fluids used in rotary drilling to 
seal the pore spaces of the wall rocks of wells, possibly to 
such a degree that access of oil and gas to the wells is 
permanently restricted. It would appear that this is 
especially likely to occur in drilling into low-pressure 
reservoir rocks where the clay is able to penetrate 
deeper into the wall rocks and where there may be insuffi- 
cient gas to clear the pores of accumulated clay when 
the wells are brought in and placed on production. 
Much may be done in preventing this by proper condi- 
tioning of the drilling fluid. In addition, the walls of 
the well may be thoroughly scraped to remove the mud 
sheath, or finely ground limestone may be added to the 
circulating fluid and the well treated with acid after 
drilling is completed. Reaction between the acid and 
limestone, with formation of carbon dioxide gas, results 
in thorough disintegration of the mud sheath. 

The sealing effect of the drilling fluid on the reser- 
voir rock exposed in the wells may be avoided by using 
oil as a drilling fluid instead of mud fluid while drilling 
through the reservoir rock. This practice leaves the 
wall rocks entirely free of accumulated colloidal mate- 
rial, so that there is nothing to restrict flow of oil and 
gas into the well. "Pressure drilling" is a closely 
related technique. Here, the pressure differential 
between the formation and the well is so adjusted that 
oil and gas flow into the well is permitted to some 
extent while drilling is in progress. Such flow prevents 
accumulation of a mud sheath on the walls of the well 
and the pores of the wall rocks are kept free of detrital 
material so that when the well is eventually completed 
a maximum rate of production for the particular reser- 
voir conditions obtaining will be secured. Pressure 
drilling requires special control equipment on the well 
head and the pressure conditions within the well must 
be carefully controlled. As yet, the process has been 
used in the California fields only to a limited extent, but 
it would appear to possess attractive possibilities for 
future development. 

IMPROVEMENT IN FORMATION SAMPLING AND 
TESTING TECHNIQUE 

In the earlier period of field exploitation in Califor- 
nia, when wells were drilled by the churn or cable tool 
method, the nature of the material in the bottom of the 
well was determined by examination of fragments 
brought to the surface by the bailer or clinging to the 
drilling bit. Such samples afforded a fairly satisfactory 
basis for determining lithologic properties and the pres- 
ence of oil could usually be determined by sight inspec- 
tion or by testing with chloroform or ether. 

Early rotary drilling did not afford satisfactory for- 
mation samples, the drill cuttings being generally too 
finely ground to allow more than approximate identifi- 
cation of the material brought to the surface by the 
circulating fluid. However, as explained in a previous 
section, this difficulty was overcome by the development 
of rotary coring tools. Under favorable circumstances, 



a core taken with a rotary core barrel may furnish an 
eminently satisfactory sample of the formation exposed 
in the bottom of the well. It is brought to the surface 
with the component strata practically undisturbed. 
The bedding planes are often clearly apparent, and if 
the core can be oriented and a survey showing the 
declination of the well at the point where the core is 
taken is available, it is possible to closely estimate the 
dip and strike of the strata. Orientation of cores was a 
matter of some uncertainty until recently, when it was 
discovered that certain minerals often present in sedi- 
ments retain some degree of polarity imposed by the 
earth's magnetic field, and delicate magnetic instru- 
ments permit of orienting the core at the surface in the 
same position relative to the compass that it occupied 
while in its natural position in the earth. 

Core samples of reservoir rocks, if unbroken and con- 
tinuous, afford a means of determining the storage 
capacity of the rock for fluids and the resistance offered 
to movement of fluids. These are factors of importance 
in estimating reserves and determining productive capac- 
ities of wells and suitable spacing intervals for wells. 
The storage capacity of a reservoir rock is estimated by 
determining its percentage porosity. This is accom- 
plished with approximate accuracy with the aid of one 
or another of several types of porosimeters. The resist- 
ance offered by a rock to flow of fluids through its pore 
spaces is measured by its permeability, which may be 
determined by means of especially designed apparatus, 
and reported in terms of a unit of permeability called a 
"darcy. " Thus, a rock having a permeability of say, 500 
milidarcys offers a certain resistance to flow, and engi- 
neers familiar with these tests are able to compare such 
a rock with other rocks of known permeability and to 
predict the performance of wells producing from them. 
Screen analyses are also made of granular rocks, after 
disaggregating them, to determine the size distribution 
of their component grains, such tests being helpful in 
predicting the permeability and drainage characteristics 
of reservoir rocks. Many of the larger oil producing 
companies today maintain well equipped field labora- 
tories in which tests are regularly made on selected 
formation samples from drilling wells, to determine 
porosity, permeability, oil saturation, water saturation, 
grain size distribution, or other special lithologic proper 
ties which may be of importance for certain purposes 
(Uren, L. C. 34, pp. 455-480). 

WALL-SAMPLING DEVICES 

The usual coring devices are designed to cut a core 
from the formation exposed in the bottom of a well. 
After a well is drilled to a depth in excess of that at 
which a core is desired, it is necessary to resort to the 
use of a wall-sampling device. Two such devices are 
available. The Baker Oil Tool Co. offers a mechanically 
actuated tool which punches a small core sample out of 
the wall of the well when properly manipulated; and 
the Schlumberger Well Surveying Corporation offers 
its services in the use of a device which drives small 
retrievable core-cutting cylinders horizontally into the 
wall of the well with the aid of explosives. 

While these wall-coring devices produce smaller cores 
than vertical core barrels, they are satisfactory for most 
purposes and are the only sampling devices available for 
use in sampling reservoir rocks exposed in the walls of 



e 






Development op Engineering Techniqu e — U r e n 



59 






;••> 






;X. 




ll 






CONTENTS OF 
FORMATION ENTERS 
TESTER 



OPERATION OF 
JOHNSTON FORMATION TESTER 



Fig. 26. Formation tester. I Courtesy 
of Johnston Formation Tester Co.) 



wells in the older fields that were drilled before core 
drilling came into use. Such sampling is necessary in 
making engineering studies of partially depleted oil 
fields with the purpose of applying secondary recovery 
methods. If core samples of the producing formation 
are necessary, the only alternative beside the use of these 
wall sampling devices in the existing wells, is to drill 
new wells from the surface and take cores in the desired 
intervals with ordinary vertical core barrels. 

HEAVY MINERAL SEGREGATION AND 
PETROGRAPHIC INSPECTION 

For correlation purposes, formation samples are 
sometimes subjected to careful microscopic inspection 
under binocular or petrographic microscopes. Binocular 
microscopes are used for preliminary inspection of 
samples to determine the lithologic character of rock 
fragments and to roughly determine the mineral content. 
Disaggregated grains of sand or sandstone may be floated 
on bromoform or other heavy liquids to segregate the 
heavier minerals which are sometimes characteristic of 
the strata in which they are found. Petrographic micro- 
scopes are used to identify individual sand grains 
mineralogically. It will often be found, as a result of 
microscopic examination or heavy mineral segregation, 
that some unusual mineral occurs in a formation sample 
from a particular stratum cored in a certain well 
(Hanna, G. D. 24; Tickell, P. G. 39). Identification of 
this mineral in a formation sample from a stratum cored 
in another near-by well, may afford a basis for correla- 
tion of strata between the two wells. The presence of 
unusual quantities of some less common rock-forming 
mineral, conferring a characteristic color or texture, may 
also serve to identify a particular ' ' marker bed. ' ' Where 
such occurrences may be used to identify a particular 
stratum, so that it can be identified over wide areas or 
perhaps throughout an entire field, the conduct of drill- 
ing operations is greatly facilitated. Determination of 
landing depths for casings, estimates of depths to pro- 
duction, and interpretation of sub-surface structural 
conditions, may rest upon accurate identification of 
stratigraphic ' ' markers. ' ' 

IDENTIFICATION OF MICRO-FOSSILS FOR 
CORRELATION 

Formation samples from drilling wells often contain 
fossil remnants of former plant and animal life, which 
may be used as a means of correlation. Fossils may be of 
macroscopic size, in which case, mere fragments of the 
complete fossil form may be all that will be found ; or 
they may be complete fossils of microscopic proportions. 
The latter are common and most useful. Of the several 
microfossils commonly found in sedimentary formations, 
the foraminifera and diatoms have been most useful for 
correlative purposes. Micropaleontologists specializing 
in this type of work are employed by many of the larger 
oil companies, and laboratories with the specialized 
equipment necessary are provided. .Selected portions of 
all cores taken for correlation purposes are sent from the 
field to the laboratory and there disaggregated, examined 
for fossils, which are separated from the inorganic mate- 
rial and identified under the microscope. In some 
regions, research has resulted in the assemblage of tables 
of microscopic life forms sufficient to identify every part 



60 



Exploration 



[Chap. II 



of the geologic column penetrated hy the wells in reach- 
ing the oil-producing horizon. Microfossils may serve to 
correlate particular horizons over the entire area of a 
field, but because of lateral variation in life forms at a 
particular time in geologic history, cannot be depended 
upon as a means of correlating formations in widely sep- 
arated regions (Hanna, G. D. 24; Tiekell, F. G. 39). 

ELECTRICAL LOGS 

A notable advance in the development of methods of 
identifying the characteristics of formations penetrated 
by a well has been made during the current decade with 
the development of the electrical method of logging. 
Originally perfected and applied in the California fields 
by the Schlumberger Well Surveying Corporation, the 
method has more recently been offered to the industry, in 
slightly modified forms, in such devices as the "Geoana- 
lyzer ' ' and the ' ' Strata-graph. " Both methods measure 
the comparative resistivity of the individual strata pene- 
trated by the well and afford an index of the relative 
permeabilities and fluid content. 

The Schlumberger Well Surveying Company offer an 
electrical logging service with trained personnel and 
equipment mounted on trucks ready to respond promptly 
to calls from operators in any California field. Each 
truck carries hoisting gear and a reeled armored, insul- 
ated, multi-wire conductor cable of sufficient length to 
reach to the depth to be surveyed. On the lower end of 
this cable, electrodes are placed, usually three in number, 
spaced a few feet apart. A supply of direct current from 
the motor truck is transmitted to the lowermost electrode. 
This current is transmitted through clay-laden fluid with 
which the well is filled, and enters the formation oppo- 
site. The difference in potential between the upper two 
electrodes, determined by a potentiometer at the surface, 
is a measure of the resistivity of the formation opposite 
which the lowermost electrode is suspended. Because of 
its superior static pressure, the drilling fluid slowly pene- 
trates the wall rocks at a rate that is proportional to the 
rock permeability. Eleetro-filtrative effects, or the ehemi- 
coelectrical effect created at the interface between the 
drilling fluid and the formation fluid, result in a self- 
induced current of small magnitude which, by suitable 
arrangement of circuits, may also be indicated and re- 
corded by instruments at the surface (Schlumberger, C. 
32; 33; 33a). 

The usual method of conducting an electrical survey 
of a, well is to lower the electrodes through the drilling 
fluid at the well, recording on photographic film in the 
service truck, two (sometimes three) parameters. One 
of these indicates the relative resistivity in ohms and the 
other the relative permeability in millivolts. A third 
parameter, sometimes recorded, is a function of the 
resistivity and indicates comparative resistivities over a 
greater distance from the wall of the well than the 
regular resistivity parameter. The resulting profiles are 
printed on photographic paper, as illustrated in Pig. 27, 
and afford continuous records, drawn to scale, of relative 
resistivities and permeabilities of all strata within the 
interval surveyed. The work may be rapidly done, an 
hour or so being sufficient to obtain a complete electrical 
log of several thousand feet of hole. 

The fluid content of each stratum, whether water, oil 
or gas, can be determined by inspection of the resistivity 



Resistivity Log "Porosity Log 
ohms m1ujvolt7 

6&33~l. • 2 a*i hi an so » iojtno to taiva 



< 






H — 'fM 



7900 ■ 



ffB ■ 






JILL 



< 



(Mo 



&XO? 



Fig. 27. Schlumberger electrical log of a well. 



'': 



Development of Engineering Techniqu e — U sen 



61 



profile by one skilled in its interpretation. The ability 
of each stratum to yield its contained fluid to the well, is 
also indicated in r, comparative way, by the permeability 
profile. The formations likely to produce water or oil or 
gas to the well may thus be estimated with fair accuracy. 
The data are helpful not only in indicating the intervals 
in which liners should be perforated to receive produc- 
tion, but are also useful in correlation work and in esti- 
mating reserves. Resistivity logs are also helpful in 
indicating: accurately the depth of the lower end of a 
column of easing in a well, or in locating metallic "junk" 
that has been side-tracked in the walls. 

Electrical measurements may also be used as a means 
of indicating the amount and direction of dip of forma- 
tions exposed in the walls of a well at any point, and of 
making directional surveys of wells. The Schlumberger 
i Well Surveying Corporation offers these services in addi- 
tion to its electrical logging service. 

TESTING TO DETERMINE FLUID CONTENT OF STRATA 
PENETRATED BY WELLS 

When a porous and permeable stratum, suitably 
capped, that may serve as a reservoir rock, is encoun- 
tered in the drilling of a well, it will be important to 
determine at once whether it contains water, gas, or oil. 
For this purpose, a "formation tester" may be used. 
'This is a device, lowered on drill pipe or tubing into the 
well, equipped with a substantial wall packer and suita- 
ble control valves, and so designed that the packer may 
be securely seated on a prepared shoulder on the wall 
of the well. The tester is then manipulated in such a 
way that the lower part of the well below the packer — 
in which interval the formation to be tested is sitnated — 
is effectively sealed off from the portion of the well 
above the packer. With the interval below the packer 
freed of the hydrostatic pressure of fluid in the well 
above the packer, valves are opened to admit fluid from 
the formation into the tubing or drill pipe on which the 
tester is suspended. The tubing has been lowered into 
the well with the inside "dry," or containing too little 
fluid to exert the normal hydrostatic head. With pres- 
sure thus relieved in the interval below the packer, a 
differential pressure is created causing fluid to flow from 
the formation into the well and up through the drill pipe 
or tubing toward the surface. Formation fluid rises in 
the tubing until an equilibrium static head is attained 
opposing further admission of fluids from the formation. 
The tester is then lifted and a valve closes in the tester, 
imprisoning the fluid in the tubing above. The tubing 
is then withdrawn to the surface and uncoupled and the 
fluid examined. Quantitative measurements of the 
amounts (or number of feet or "stands" of pipe) of oil, 
gas, salt water, and drilling fluid, will give evidence of 
the character of fluid that might be expected in subse- 
quent production from the interval tested. If the forma- 
tion pressure is sufficiently high, sustained flow of fluid 
from the interval under test to the surface may result, 
affording an actual production test. Repeated applica- 
tion of the formation tester at different depths in a well 
will show the character of production and comparative 
productivities of the different intervals tested. 

In addition to formation samplers which depend 
upon securely seating a packer against the wall of the 
well, fluid sampling devices, designed merely to entrap 



a small sample of the well fluid at any desired depth, 
are also available. Before the development of formation 
testers, fluid samples were obtained with greater diffi- 
culty/and delay in drilling operations. A string of cas- 
ing had to be set and perhaps cemented to exclude top 
waters, and fluid was then bailed from the well until 
the fluid level fell to the level of the casing shoe, when 
samples of fluid from the formation below that point 
could be obtained. 

ANALYSIS OF FORMATION WATERS 

To facilitate their identification at a future time, 
analyses may be made of all ground waters obtained dur- 
ing the course of drilling. Such an analysis may be a 
complete chemical analysis from which the reactivity of 
the water may be predicted ; or the salinity is deter- 
mined and only the chloride content in parts per million 
is reported. If a complete chemical analysis is available, • 
the chemical character of the water may conveniently be 
expressed in accordance with the Stabler-Palmer System 
of chemical hydrology and graphically charted on tri- 
angular coordinates (Uren, L. C. 34, pp. 481-485). 
Ground water analyses, suitably expressed and coordi- 
nated with the stratigraphic record, may be found help- 
fid during the future period of productivity of a well 
in identifying the sources of entering waters. Differ- 
ences in the chemical character of ground waters in dif- 
ferent strata may serve as a basis for correlation of 
strata between wells. Knowledge of the chemical rela- 
tionships may also enable one to predict whether a par- 
ticular water sample is "top water" or "edgewater. " 

IMPROVED FIELD DEVELOPMENT PRACTICES BASED 

ON BETTER KNOWLEDGE OF DEEP-SEATED 

RESERVOIR CONDITIONS 

A notable advance has been made during the last 
fifteen years in our understanding of the manner of 
occurrence and behavior of oil and gas in deep-seated 
reservoirs. That formation pressures are high was previ- 
ously known, but no dependable means of determining 
them with accuracy was available until the development 
of bottom-hole pressure-recording devices. Studies of 
the pressure and energy gradients within the reservoir 
rock have brought new concepts of the mechanics of 
radial drainage. Accurate studies of the geothermal 
gradient in many oil fields have afforded more dependa- 
ble data on the actual temperature of the reservoir fluids 
than previously existed. Studies of the solubility of 
natural gas in crude petroleum have disclosed that at 
high formation pressures, very large volumes of gas may 
be held in solution in the oil and that in this condition, 
the viscosity and surface tension of the oil is much 
reduced. The volume is increased and the density 
diminished. Knowledge of these factors, together with 
studies of hydrocarbon phase relationships and com- 
pressibilities of natural gases at high pressures have 
enabled research workers to determine the formation 
volumes of oil-gas mixtures when in place in the reser- 
voir rock. Studies have also indicated that reservoir 
rocks apparently saturated with oil and gas, may con- 
tain important quantities of connate water in their inter- 
stitial pore spaces. Laboratory research and application 
of the concepts of fluid mechanics to oil reservoir con- 
ditions have contributed much to our knowledge of the 



62 



Exploration 



[Chap. II 



characteristics of flow of gas-oil mixtures through reser- 
voir rocks. 

Better understanding of the conditions existing 
within oil reservoir rocks and of the factors influencing 
drainage have within recent years begun to influence 
field development practices. More careful consideration 
has been given to the problem of economic well spacing, 
with the result that there has been a decided tendency 
toward wider spacing of wells than formerly. New sys- 
tems of field development have come into vogue, 
emphasizing the necessity for preservation of gas caps 
and control of edge water incursion. Conditions in the 
California fields have focused attention especially upon 
field development systems adaptable to multi-zone 



deposits throughout great thicknesses of producing for- 
mations. Modern theories of drainage have emphasized 
the necessity for proper methods of field pressure 
control. 

These topics that have been dismissed with hardly 
more than a sentence of comment, are in reality subjects 
of great interest to the modern petroleum engineer. 
They are the avenues by which we may hope to approach 
a future system of oil field exploitation far more efficient 
than any that has been known in the past. Yet they 
represent but one of many phases of California's great 
oil and gas industries that are being currently advanced 
by application of modern scientific knowledge and engi- 
neering skill. 




Fig. 27 A. In Pennsylvania, Drake brought in his historic first well 
in 1859. This view was taken in 1S63. Colonel Drake is in 
the foreground, wearing the high hat. (Courtesy of Standard 
Oil Company of California.) 



Fig. 27 B. Recent photograph of Pico No. 4 well, Pico Canyon, 
near Newhall. Drilled to 370 feet in 1876 and pumped 25 
bbls. oil per day ; later deepened with better results. If not 
the earliest, this represents one of the first successfully pro- 
ductive wells in southern California. (This field will be 
described in Part Three.) (Courtesy of Standard Oil Com- 
pany.) 



MECHANICS OF CALIFORNIA RESERVOIRS 

By Stanley C. Herold* 



OUTLINE OP REPORT 

Page 

Scope of reservoir mechanics 63 

Conditions encountered in California 63 

Mechanics of natural production 63 

Mechanics of forced production 65 

Drainage 65 

Effect of curtailment 66 

Conclusion 66 



SCOPE OF RESERVOIR MECHANICS 

Reservoir mechanics, as a science, progressed rather 
leisurely through many years in California until several 
months ago, when it broke into prominence, attracting the 
attention of petroleum geologists and petroleum engi- 
; neers. The problems of migration, accumulation, well 
: spacing, reserves, ultimate recovery, percentage recovery, 
repressuring, pressure maintenance, gas energy, edge- 
I water energy, edgewater encroachment, paths of fluid 
I movement, pressure gradients, velocity gradients, bottom- 
hole pressures, indices of productivity, and the applica- 
tion or interpretations of gas-oil ratios, core analyses, 
1 porosity, permeability, surface tension effects in mixtures 
i of gas and oil or water and oil, require the consideration 
of theoretical and applied mechanics. It is not unfair to 
i state at the present time that merely a beginning has been 
; made in the study of these matters. 

CONDITIONS ENCOUNTERED IN CALIFORNIA 

The class of reservoirs encountered in California is 
! not confined to this State, but exists in the other fields of 

the world where production is obtained from formations 
; of Cenozoic age. Notably it is in the United States, east 
1 of the Rocky Mountains, where production is obtained 
! from formations of Paleozoic age, that another great 
: class of reservoirs is encountered. Peculiarly enough, 
i the reservoirs within formations of Mesozoic age appear 

to be divided, some belonging to the one, and some be- 
; longing to the other class. These classes are entirely 
! distinct in their performance. The respective wells 
j respond differently when we manipulate the production 

coming from them. That which is good practice in the 

j one region is not necessarily good practice in the other. 

Many of our California reservoirs lie at great depths 

varying between 8,000 and 13,000 ft. below the surface. 
: These in particular demand our attention in mechanics. 

The drilling of a single well means an investment of 

between $100,000 and $350,000, exclusive of expensive 
| mishaps. Natural flow from these wells offers no diffi- 
culty, but gas-lift and pump problems are serious. We 

must do what we can to foice the wells to produce the 

srreatest possible quantities of oil at the least cost. The 
! proper mechanical completion of such wells is also a 
[serious matter. Producing zones vary in thickness be- 
tween 100 and 3,000 ft. Zones consist of massive sand 

bodies separated often by impermeable layers of shale 

from 2 to 200 ft. in thickness. Sometimes the massive 



sands of different porosities and permeabilities lie in con- 
tact without the intervening layers of shale. 

The shales are of ordinary firmness, while the sands 
vary in competency. Small samples frequently crush 
easily in the hand, others will withstand a light blow 
from a hammer, and a very few possess the hardness of 
older sedimentaries. No shooting is required to bring in 
a California well. In fact, perforated pipe must be used 
to prevent the formation from coming to the surface in 
separated sand grains. According to the records of 
mechanical and electrical logging, the shales are more 
continuous over a structure than the sands which are 
lenticular. Laterally they are not homogeneous in tex- 
ture, in firmness, or in thickness. Although in single 
profile sections the lenses appear separated and overlap- 
ping throughout a zone, from the behavior of wells in 
the zone we are certain that no lenses are entirely sealed 
off so as to be mechanically independent of edgewater 
pressure. If we could construct a complete system of 
parallel profile sections we evidently would be able to 
trace each lens outward to the edge of the pool. A com- 
pletely sealed lens, if encountered, can be recognized, 
because a well penetrating it would give only gusher 
production, and would at no time be endangered by en- 
croaching edgewater. 

Outcrops of producing sands are at elevations vary- 
ing between 400 and 1,800 ft. above sea level. Hydro- 
static heads measured from producing horizons to these 
outcrops are sufficiently great to account for closed-in 
reservoir pressures varying between 2,000 and 4,000 lb. 
per sq. in. 

MECHANICS OF NATURAL PRODUCTION 

Gusher production is caused by the energy of the 
compressed gas which is present with the oil; settled 
production is caused by energy of the edgewater. In the 
former period the gas expands and performs work upon 
the oil ; in the latter period the gas continues to expand 
as it approaches the well, but it does so merely to accom- 
modate itself to a decreasing pressure. It does no work 




.fa level 

' Top or Brown Shale 

Midpoint of Penefrsl'cn 



Lowest Closed Contour 



Top of Temblor 



Verticil Sale E taygtrsrec! 



•Consulting Geologist and Engineer; Los Angeles, California. 
Manuscript submitted for publication July 1, 1939. 



Fig. 28. Cross-section showing Temblor formation, from Tar 
Canyon to Shell Armstrong Well No. 1. Direction N. 40° 
30' E. 



64 



Exploration 



[Chap. II 



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Fig. 29. Daily production record for 1929 of Kettleman Hills discovery well. 



DAII.T HBOHD Bill 1.-1 




Fig. 30. Recomputed production record for 1929 of Kettleman Hills discovery well. 



J 



Mechanics op California Reservoir s — H erold 



65 



upon the oil at this time. Edgewater performs work by 
virtue of encroachment upon the pool . 

Before curtailment, the production curves of Califor- 
nia wells clearly indicated the class of reservoirs from 
which they produced. Manipulations of the wells to suit 
allotments of production of course interfere with the 
normal paths of decline dictated by nature. 

A typical mechanical profile of a producing California 
field appears in Fig. 28. This happens to be designed to 

, meet conditions at Kettleman Hills, but with different 
scales it can be made to suit any simple anticlinal struc- 
ture in the San Joaquin Valley, the Los Angeles Basin, 
or the Coastal area of the State. Structures other than 
simple anticlines require slight modifications in accord- 
ance with known conditions. Nevertheless, the general 
mechanical situation is the same. All energy possessed 
by gas on the crest of the structure is the result of the 

I pressure of the column of water which extends upward 
toward the outcrop. 

The discovery well at Kettleman Hills, Milham 
Exploration Company Elliott No. 1, produced approxi- 
mately a year without the competition of offset wells, 

; and without curtailment. Its daily production record 
appears in Pig. 29. The daily irregularities in produc- 
tion are typical of wells with high gas-oil ratios wherein 
the amount of oil at the bottom of the hole continually 
changes, offering a variable back pressure against the 

i face of the sand. In this case, more prominent irregular- 
ities were caused by changes made in the flow nipple at 
the head of the well in an attempt to get the best pro- 
duction results. 

The first set of irregularities may be removed bj' 
computing averages for the month, and the second set 
can be largely nullified by calculating production rates 
per sq. in. of flow-nipple area. Thus the decline is 
shown as in Pig. 30. The drop in September marks the 
time when the first offset well began to produce. Its 
effect was of short duration. The change from gas expan- 
sion to water drive took place about June first, eight 
months after the well was brought in. With less gas 
the period of gas expansion would have been shorter. 

' The usual time in other California fields varies between 
four and six months. 

Had other wells not been drilled, and had produc- 

, tion continued from this well uninterruptedly, the water 
drive would have continued on a straight line until a 
point had been reached when another turn would have 
made the continued record lie on a straight horizontal 

| line. Then there would have been no further decline in 

;the rate of production. In such an event, however, the 

joil would inevitably have been replaced by water, 

although this would have required many years, in view 

of the location of the well with respect to the edgewater. 

The production from other wells provides for a 

i greater decline before the curve strikes off horizontally. 

MECHANICS OF FORCED PRODUCTION 

The gas lift and the pump rejuvenate wells by reduc- 
; ing the back pressure against production. They perform 
no other function. There is a decided advantage in con- 
serving reservoir gas during the stage of natural flow. 
| Such conservation puts off the day when the artificial 
igas lift must be installed. Thus may total compression 
■ (costs be reduced. 




Fig. 31. "Lines of flow into two interfering wells in a region in 
which the ground water has a motion in a general direction. 
The diagram assumes that the general motion of the ground 
water is from north to south." 

(Reproduced from Sliehter, C. S. 99, p. 370, fig. 85.; 

At the end of the period for the artificial gas lift all 
gas energy in the reservoir has been squared off. The 
oil remaining must either be pumped or abandoned. 
Whether the amount of this oil is or is not dependent 
upon conservation or waste of gas energy during natural 
flow is a controversial question among engineers. 

The problem of pumping wells that exceed 8,000 ft. 
in depth as yet has not been solved. 

DRAINAGE 

Technological features of drainage in particular fields 
have not been studied seriously. In California the 
underground flow lines for oil and gas are the same as 
the ordinary flow lines for water anywhere in the world. 
(Flow lines in the class of oil reservoirs encountered in 
Paleozoic formations are quite different. Undoubtedly 
this fact has hindered the study of drainage patterns in 
general.) 

Everyone is familiar with the design of Fig. 31, 
(Sliehter, C. S. 99, p. 370, Fig. 85). W 1 may be assumed 



66 



Exploration 



[Chap. II 



to be a well a considerable distance down the flank of a 
structure, while W L , is a well higher on the flank. Off 
the diagram at the base another well, W„ may be imag- 
ined on the crest of the structure. Production of these 
wells causes a movement of oil and gas from the top to 
and beyond the bottom of the figure. A perfectly homo- 
geneous sand is assumed. In actual field cases certain 
variations are brought into play. Wells are frequently 
numerous, although generally spaced equally; they are 
sometimes staggered with respect to the edgewater line, 
or staggered with the direction of flow lines up the 
structure; and production rates are seldom equal at the 
various wells. Furthermore, the sands are heterogeneous. 
Wells in California can not produce beyond their 
gusher stage without draining oil and gas (or water) 
from adjoining property. Thus a well may produce 
more oil than can be contained in the total amount of 
pore space underlying a particular property. 

EFFECT OF CURTAILMENT 

Curtailment is technologically beneficial to the recov- 
ery of oil in this State. Slower rates of production per- 
mit the leveling off of edgewater at the base of the struc- 



tures, and they reduce the amount of gas by-passing the 
oil in the movement of gas and oil toward the wells. 

The use of production curves has been greatly 
restricted since the introduction of curtailment. It is 
practically impossible to obtain any such curve as is 
shown in Pig. 30. However, one remedy seems possible, 
and that is to change the abscissas and ordinates to 
accumulated production and closed-in bottom-hole pres- 
sures, respectively. Thus the element of time, as it now 
appears in both coordinates, is avoided. The resulting 
curve will appear exactly the same as in Fig. 30, except 
as to the scales, with their titles as stated. 

CONCLUSION 

Economic conditions require the immediate consid- 
eration of well spacing, reserves, percentage recovery, 
and pressure maintenance. Along these lines there is 
much divergency of thought undoubtedly caused by the 
absence of any underlying system of mechanics to 
describe competently the events and conditions within a 
producing reservoir. Unity of thought based upon a 
system is essential before we can accomplish our aim in 
technology. 









GEOPHYSICAL STUDIES IN CALIFORNIA 

By F. E. Vauohan* 



OUTLINE OF REPORT 

Page 

Introduction 67 

Ebtvbs torsion balance surveys 67 

San Joaquin Valley 67 

Santa Maria Valley 68 

Los Angeles Basin 68 

Imperial Valley 68 

Oxnard Plain - 68 

Magnetometer 69 

Holweck-Lejay pendulum and the gravimeter 69 

Refraction seismometry 69 

Electrical methods 70 

Reflection seismometry 70 



INTRODUCTION 

One of the greatest steps in the advancement of the 
geological sciences made during the past half century is 
the development of physical methods for field studies. 
For more than 16 years rather extensive surveys have 
been made in connection with the search for oil and 
other mineral accumulations. Several methods have been 
employed in California and it -is the purpose of this 
paper to show in a general way the progress of geophysi- 
cal studies in this State. 

Since geophysical surveys are rather expensive, spe- 
cial emphasis is usually placed upon their usefulness in 
directly determining local structures of economic value. 

; However, they are fully as important in throwing light 
upon many of the more fundamental problems of tec- 
tonic geology ; indeed, they promise to afford definite 
solutions of some problems heretofore held to be entirely 
of a speculative character. The importance of this phase 
of geophysical work should be stressed, since proper 
theoretical considerations are of great value to the eco- 

i nomic geologist in helping him gain and retain a clear 
picture of the structural relationships throughout a 
large district and enabling him to focus more effectively 
his attention upon certain restricted portions of the 
district. 

We shall take up the various methods which have 
been employed here, outlining some of their more out- 
standing accomplishments and, in a general way, indicat- 
ing the usefulness and limitations of each. 

E6TV0S TORSION BALANCE SURVEYS 

The usefulness of any gravimetric method is depend- 
ent upon the principle that distributions of gravitational 
i forces over the earth's surface are in some measure indic- 
j ative of the distributions of masses below the surface, 
' and that a knowledge of such distributions of masses 
affords evidence of geologic structure. The Eotvos tor- 
sion balance was the first field instrument capable of 
> making gravimetric surveys of sufficient accuracy to 
• show clearly the influence of local distributions of 
masses. Surveys with this device were begun in Califor- 
i nia in 1924 by the Shell Oil Company. Later the Texas 

•Geologist. Los Angeles, California. Paper presented before 
the American Institute of Mining and Metallurgical Engineers Octo- 
ber 1939; permission to publish granted by the Secretary of the 
Institute, January 23, 1940. 



Company, Western Gulf Oil Company, and Pure Oil 
Company made important surveys. Other companies 
were also active from time to time, but their work was 
by no means so extensive as that carried out by the 
four companies mentioned. 

Torsion balance surveys were extended to cover the 
Los Angeles Basin, Santa Maria Valley, Oxnard Plain, 
southern portion of the San Joaquin Valley, and a small 
part of Imperial Valley. In two areas, the San Joa- 
quin and Santa Maria Valleys, torsion balance surveys 
effected a considerable revolution in the understanding 
of the structures buried beneath the flat valley floors. 

SAN JOAQUIN VALLEY 

To the east of the San Joaquin Valley rise the Sierra 
Nevada, the outcropping basement complex comprising 
granitic rocks with important included masses of slates, 
schists, and other metamorphics. The densities of these 
rocks vary from 2.5 to 2.8, the average being approxi- 
mately 2.7. The lighter rocks are slates, granites, and 
granodiorites, the heavier are gabbros and dark horn- 
blende diorites. In a general way these rocks consti- 
tute a huge tilted block rising eastward to the high sum- 
mits of the Sierra Nevada and dipping westward beneath 
the San Joaquin Valley. This block has long been under- 
stood as belonging to the Great Basin structural system. 
Its eastern limit is a great fault whose vertical displace- 
ment in some places approximates 7,000 ft. This fault 
now finds topographic expression in the Sierra Nevada 
scarp facing the Basin Ranges. The Wasatch block in 
Utah with its conspicuous westward-facing scarp, con- 
stitutes a member somewhat similar to the Sierra Nevada 
block. Between these widely separated units, down- 
faulted and tilted blocks comprise the Basin Ranges. 

West of the San Joaquin Valley are the Coast Ranges, 
the slopes of which rise rather more abruptly from the 
valley floor than does the slope of the Sierra Nevada on 
the east side. The maximum elevations attained by the 
former are less than half as great as those attained by 
the latter. The Coast Ranges comprise a great mass of 
Cretaceous and Tertiary sediments with occasional out- 
crops of granite and Franciscan (Jurassic ?) rocks which, 
however, are very important in certain areas. The sedi- 
ments vary in density from 1.9 to 2.5, averaging approxi- 
mately 2.35. The entire mass has been subjected to 
strong compressional forces which have produced numer- 
ous folds and overthrusts, features recognized as of 
Appalachian character. The eastward dips, seen in the 
outcrops along the western margin of the San Joaquin 
Valley, give the impression that there is a major synclinal 
axis beneath the valley floor. 

Such is the general picture of the structural environ- 
ment of the San Joaquin Valley. The structure out 
beneath the valley floor was unknown before the intro- 
duction of the torsion balance. Three notions were 
rather generally accepted: (1) a dominant synclinal 
axis was believed to lie somewhere near the geographical 
axis of the valley; (2) the valley was believed to be a 
zone of demarcation separating two entirely different 



68 



Exploration 



[Chap. II 



COAST RANGES 



SIERRA NEVADA 



SAN JOAQUIN VALLEY 



BASIN RANGES 






A GEOLOGIC STRUCTURE OF SAN JOAQUIN VALLEY 



1ILLS 

SANTA MARIA VALLEY 

SAMTA MARIA RIVER; 



NIPOMA MESA 




B GEOLOGIC SECTION ACROSS SANTA MARIA VALLEY 



Fio. 32. 

types of structure, the block faulting of the Basin Range 
system and the structures of Appalachian type of the 
Coast Ranges; (3) the valley was believed to be a great 
trough sinking beneath a load of sediments brought 
down from the Sierra Nevada. 

Complete description and a complete detailed analysis 
of the torsion balance data do not lie within the scope of 
the present paper; rather, we are primarily concerned 
with the actual results in terms of geologic structure. The 
torsion balance work showed that the Sierra Nevada 
block continues westward beneath the San Joaquin Val- 
ley almost to the flanks of the Coast Ranges. It is clear, 
therefore, that the San Joaquin Valley is strongly 
asymmetric, the synclinal axis lying close to the western 
margin. No longer can we consider this valley as sep- 
arating two entirely different types of structure. On 
the contrary, we see that the Basin Range type of 
structure really extends to the margin of the Coast 
Ranges; indeed, it seems likely that these latter are 
themselves a part of the same structural system. The 
structural differences that exist between the Coast 
Ranges and the Basin Ranges appear to be due to the 
differences in the types of roots upon which the orogenic 
forces have been working ; that is to say, they are due 
to the great mass of weak rocks in the Coast Ranges in 
contrast to the strong rocks of the Sierra Nevada. There 
is an abundance of evidence indicating that the western 
part of the Sierra Nevada-Great Valley block did not 
sink because of the load of sediments upon it, but 
because of the same compressive forces as are evidenced 
by the folds and overthrusts of the Coast Ranges. 
Under these forces the great block was tilted, the west- 
ern part being forced down below its position of isostatic 
equilibrium, while the eastern part was raised above its 
position of equilibrium. 

Considerable difficulty was experienced in attempt- 
ing to determine local structures of economic value by 
means of the torsion balance. Local variations in density 
near the surface are frequently so great as to obscure 
the influence of structures at greater depths within the 
sedimentary mass. In many places, particularly along 
the eastern portion of the valley, the variations of density 
within the basement complex influence the distributions 
of gravitational forces more strongly than the structures 
within the sedimentary blanket. This is unfortunate, 
since these latter are the structures of primary interest 
to the petroleum geologist. The torsion balance did not 



lead directly to the opening of any new field, but did 
give a more exact knowledge of the general geologic 
structures in the various areas and paved the way for 
later work which has succeeded in finding new fields. 

SANTA MARIA VALLEY 

The Santa Maria Valley opens westward toward the 
Pacific Ocean. The Santa Maria River skirts the north- 
ern border of the valley, and farther to the north 
stretches the Nipoma Mesa. For the most part the 
older rocks are hidden by recent sediments, old sand 
dunes being rather extensive. A few outcrops of Fran- 
ciscan (Jurassic?) and Tertiary sediments are found, 
but they tell little of the geologic structure. The Cas- 
malia Hills bordering the valley to the south are due to 
a rather important anticline involving Tertiary sedi- 
ments. The north limb of this anticline dips toward the 
valley. The structure beneath the valley floor was 
unknown, but one conjecture seemed to prevail. Because 
of the strong development of the Casmalia Hills anti- 
cline and the general northward slope of the valley 
floor, it was thought likely that there Were other folds 
immediately to the north, more or less parallel to the 
Casmalia Hills anticline and becoming less important 
toward the Santa Maria River. Because of the general 
southerly slope of the Nipoma Mesa and numerous 
southerly dips farther to the north, it was thought that 
the general structure in this area also dipped toward the 
river. Thus in a general way it was believed that the 
axis of a broad synclinal trough was near the Santa 
Maria River. 

The torsion balance survey completely upset the 
foregoing conception. It showed that the surface of 
the basement rocks slopes southward beyond the Santa 
Maria River and almost to the southern margin of the 
valley. The north limb of the Casmalia Hills anticline 
was found to continue its steep dip northward into the 
valley. Thus it became clear that the Santa Maria 
Valley is structurally a broad asymmetric syncline whose 
axis lies close to the southern margin of the valley. 

LOS ANGELES BASIN 
The torsion balance survey did not change greatly 
the conception of the structures underlying this area. 
Hydrographic surveys had already shown the presence 
of a basin separated from the ocean by a structural high 
along the coast except for an opening to the ocean north- 
west of Newport Beach. The torsion balance survey 
indicated that the deepest part of the basin lies near 
Huntington Park and that from this locality a synclinal 
trough extends toward Anaheim and then southward to 
the oceaii northwest of Newport Beach, thus agreeing 
in the main with the earlier conception. 

IMPERIAL VALLEY 

Only a small area was covered and this was done 
under contract for some eastern company. However, 
little was learned of structures within the sedimentary 
mantle. The more important features in the gravita- 
tional field here are due to density variations within the 
basin complex including those due to dikes and volcanic 
necks. 

OXNARD PLAIN 

The most interesting observation on the work here is 
that a large part of the gravitational field is completely 



Geophysical Studies in Californi a — V aughan 



69 



dominated by the heavy igneous masses at the northern 
extremity of the Santa Monica Mountains. These masses 
extend beneath the plain and beneath the ocean for a 
considerable distance north of the most northerly out- 
crops. 

MAGNETOMETER 

The magnetometer was introduced into California in 
1926 and has been used from time to time ever since by 
various companies. The Standard Oil Company made 
the most extensive surveys, covering the Oxnard Plain 
and a large part of the San Joaquin Valley. 

In a general way it can be said that the magnetometer 
was not able to find structural features that could not be 
determined either by the torsion balance or by the 
regular field methods of mapping. It was very much 
cheaper than the torsion balance, but far more limited 
Jin its range of usefulness. In some places it supple- 
mented the torsion balance; as for example along the 
east side of the San Joaquin Valley, where variations in 
the magnetic field were found to be in marked agreement 
with variations in the gravitational field. Magnetometer 
surveys carried eastward beyond the contact between the 
sediments and the basement complex showed that a num- 
ber of features in the distribution of magnetic forces 
extend across this contact entirely uninfluenced by it. 
It is clear, therefore, that these features must be due to 
variations within the basement complex. 

In the Oxnard Plain the magnetometer showed the 
dominance of the influence of volcanic rocks at the north 
end of the Santa Monica Mountains in somewhat the 
same manner as did the torsion balance. 

Perhaps the greatest importance of magnetic studies 
lhas not been in the usefulness of the magnetometer itself 
in exploration work, but in an outgrowth from this work. 
I refer to the method of orienting cores as developed by 
Edward D. Lvnton and Henrv N. Herrick (Lvnton, E. 
D. 37, 38; Roberts, D. C. 39)." 

HOLWECK-LEJAY PENDULUM AND THE 
GRAVIMETER 

The Holweck-Lejay inverted pendulum is intended 
for making general gravimetric surveys over large areas. 
About three years ago the Shell Oil Company began 
work near Hanford and carried the gravimetric survey 
northward to include virtually the entire Sacramento 
Valley. This survey confirmed what had already been 
inferred from previous work in the San Joaquin Valley 
I — that the Sacramento Valley is structurally similar to 
: the San Joaquin Valley and that the two valleys are 
structurally a unit. The Sierra Nevada basement block 
slopes westward beneath the Sacramento Valley and 
the axis of the synclinal trough of the valley is close to 
the western margin. 

Gravimeters are used for making both general and 

! detailed gravimetric surveys. A considerable number of 

| designs are employed, but all depend on measuring the 

force due to gravity upon a mass suspended by some 

■ sort of a spring device. 

In California the Continental Oil Company has made 

, gravimeter surveys in the Los Angeles Basin, the Santa 

Maria Valley, and the San Joaquin Valley. The Western 

I Gulf Oil Company also made extensive gravimeter sur- 

j veys in the San Joaquin Valley and may have carried on 



similar work elsewhere. The results of these surveys are 
not known to the writer, but it seems likely that they 
have yielded somewhat the same geological information 
as has the torsion balance or the Holweck-Lejay pendu- 
lum, depending upon the spacing of the points of obser- 
vation. 

REFRACTION SEISMOMETRY 

This work is essentially the study of artificial seismic 
waves set up by heavy explosions which have penetrated 
the earth to deep high velocity zones and then have come 
back to the surface. Experimental work was carried on 
in California early in 1925, but not until the summer of 
1927 was there any regular survey made. At that time 
the Shell Oil Company began operations in the San 
Joaquin Valley. Later the Standard Oil Company did 
some work on the west side of the San Joaquin Valley. 
Several parties were active from time to time for the next 
three years, but they were on contract work and it is 
not known with certainty for what companies they were 
working. No really extensive surveys were carried out, 
as it was soon learned that in California the usefulness 
of this method is rather limited. Moreover, the costs of 
operations were very high ; dynamite alone was a con- 
siderable item as some parties used more than two car- 
loads per month. Damage claims were frequent, and, 
although actual damage done was slight, they offered a 
real obstacle to the progress of operations in populated 
areas such as the Los Angeles Basin and the Oxnard 
Plain. 

The method was useful in definitely proving the cor- 
rectness of some of the interpretations of torsion balance 
surveys ; for it must be remembered that the earlier work 
was of a pioneering character without the background of 
experience and it was felt that many of the findings were 
so radical as to require additional support. The seismo- 
graph was able in some instances to give approximate 
quantitative results where the torsion balance findings had 
been purely qualitative. A good example of this is 
afforded in the San Joaquin Valley where it not only 
confirmed the understanding of the general structure as 
determined by the torsion balance, but also showed the 
general conformation of the surface of the basement 
complex under the eastern part of the valley floor. In 
the latitude of Hanford the basement surface was fol- 
lowed from the eastern margin of the valley to a point 
four miles west of the town. At this locality the strike 
of the surface is approximately N. 20° W. and the dip 
is approximately 5° SW. While it would have been pos- 
sible to follow the basement farther to the west, this was 
not done, as interest was centered primarily in structures 
involving the overlying sediments. However, refraction 
studies of these sediments showed clearly, although indi- 
rectly, that the general attitude of the basement surface 
as found near Hanford, and eastward to the margin of 
the valley, continues westward into a synclinal trough 
well over toward the west side of the valley, close to the 
margin in some places. While subject to a considerable 
error, the results seem to justify an estimate of at least 
30,000 ft. for the depth to the basement complex in the 
trough of the syncline near the western margin of the 
valley east of the Coalinga nose. This more exact knowl- 
edge of the structure of the valley afforded some clues 
regarding the actual mechanics of the formation of the 



70 



Exploration 



[Chap. II 



valley, a matter which cannot be dealt with properly in 
this paper. 

In the Santa Maria Valley the refraction seismograph 
also gave quantitative results where previously only qual- 
itative had been obtainable. The survey showed that 
from a point on the Santa Maria River about six miles 
northwest of the town of Santa Maria the basement sur- 
face slopes approximately 7° southward to the vicinity 
of Betteravia. 

ELECTRICAL METHODS 

There are many electrical methods in existence, each 
one of which places emphasis on some particular pheno- 
menon. They include studies of natural currents in the 
earth, direct current, alternating current, electromag- 
netic waves, resistance, inductance, capacitance, etc. 
Some of these have been tried in California, but none has 
proved to be a noteworthy success as a means of field 
exploration in the ordinary sense of the term. However, 
an outgrowth of this work, the Schlumberger electric log, 
has proved to be exceedingly valuable in the study of 
drilling wells. 

REFLECTION SEISMOMETRY 

Reflection seismometry is the study of artificial seis- 
mic waves, generated by small shots of dynamite, which 
have penetrated the earth to some depth and have been 
reflected back to the surface of the ground from bound- 
ary surfaces between rocks which transmit seismic waves 
with different velocities. This method is somewhat slower 
than the refraction method in covering large areas in 
those regions where both will discover the important 
structures, as for example in the Gulf Coast region where 
both have been successful in finding salt domes. How- 
ever, it has proved to be effective in many areas where 
no other method has been at all satisfactory. It is 
capable of measuring dips and strikes and of carrying 
correlations in structures of small pattern. Besides its 
success in making measurements it has a distinct ad- 



vantage over gravimetric, magnetometric, and electrical 
methods in that the quantities used are familiar to the 
geologist. 

Reflection seismometry has met with considerable suc- 
cess in California. Some of the more important discover- 
ies for which it is responsible are the Ten Section, 
Greeley, Cole's Levee, and Terminal Island fields. All 
of the major companies in California, and some of the 
independents as well, recognize its value and are very 
active in its application. Most of the more generally 
recognized oil territory in California has been shot over 
at. least once. This includes the Los Angeles Basin, 
Oxnard Plain, Santa Maria Valley and the San Joaquin 
Valley south of Hanford. Some work has also been done 
in various parts of the Great Vallev northward nearly to 
Red Bluff. 

Reflection shooting has added considerably to our 
knowledge of the general tectonic geology in several parts 
of the State. In this connection I wish to draw special 
attention to some work done in the Los Angeles Basin 
under the supervision of B. Gutenberg and J. P. Bu- 
walda of the California Institute of Technology (Guten 
berg, B. 35). Many geologists have long believed that 
block faulting has been important in the development of 
the Los Angeles Basin, and the work by Gutenberg and 
Buwalda bears out this conception. They adduce evi 
dence which seems to show that there is a huge block of 
the basement mass dropped down between the Inglewood 
and Norwalk faults. The upper surface of this graben 
lies some 45,000 ft. below the surface of the ground. 
Other blocks on either side lie at depths of from 10,000 
to 20,000 ft. 

Methods and equipment used in reflection shooting 
have been improved greatly during the past four years, 
and some areas have been shot over as many as three 
times by the same company. Judging from the history 
of similar activity elsewhere as well as the progress here 
up to the present time, it seems likely that this work will 
continue in California for several years. 



GEOCHEMICAL PROSPECTING FOR PETROLEUM 

By E. E. Rosaibe* 



OUTLINE OF REPORT 

Page 

Geochemistry of a petroleum deposit 71 

Types of phenomena recognized in geochemical prospecting 71 

Near-deposit phenomena 71 

Near-surface phenomena 71 

Conclusions 71 



GEOCHEMISTRY OF A PETROLEUM DEPOSIT 

The mining geologist finds it quite necessary that 
consideration be given to the geochemistry as well as the 
geology of an ore deposit, yet, in exploration for petro- 
leum, there has been no fundamental recognition of the 
possible existence of the geochemistry of a petroleum 
accumulation. 

In fact, there has been a tendency to consider the 
oil and gas in place as an inert and static mass, similar 
to a coal seam. This existing viewpoint is natural in 
consideration of a stripper field, where work must be 
done to extract the petroleum from its sedimentary 
environment. 

Consideration of a wild well, however, will lead to a 
better understanding of the conditions existing in an 
untapped petroleum accumulation, where rock pressures 
drive the hydrocarbons into and through the immedi- 
ately surrounding sediments. Even though the sedi- 
ments are considered relatively impermeable, one must 
admit, as a minimum, the leakage of minute amounts of 
hydrocarbons at slow rates outward from the deposit, 
along the bedding planes of the more permeable zones 
and across bedding planes through normal joints and 
fissures. 

Even though such leakage is small, and takes place 
at a slow rate, accumulated over long geologic time, it 
can today be measured in several ways with relative 
ease. Proper recognition and consideration of these 
phenomena permit the organization of rational prospect- 
ing techniques which aim at the recognition and loca- 
tion of the petroleum itself, not just the geometry of 
traps within which petroleum might possibly be accumu- 
lated. 

TYPES OF PHENOMENA RECOGNIZED IN 
GEOCHEMICAL PROSPECTING 

In geochemical prospecting, we recognize two general 
types of phenomena, the near-deposit type, and the near- 
surface type. The former is of importance in geo- 
chemical well logging, accomplished by analysis of cut- 
tings and cores from wells. The near-surface phenomena 
are of importance in prospecting along the surface, 
accomplished by the chemical analysis of soil samples, 
and the physical measurement of the properties of the 
near-surface sediments. 

The element of depth enters into the near-deposit 
phenomena, whereas the element of geological time, 
rather than depth, enters into the near-surface phe- 
nomena. 



•Geophysicist and Geochemist, Rubterrex. 
mitted for publication February 9, 1940. 



Manuscript sub- 



NEAR-DEPOSIT PHENOMENA 

Geochemical well logging is a recently developed 
technique which depends upon the analyses of cuttings 
and cores from drilling wells. Figs. 33A and 33B illus- 
trate the differences observed between a dry hole and a 
producing well. The observed differences are many 
times the observational errors in the analytical deter- 
minations, and show how the geochemical influence of a 
petroleum accumulation may extend as much as a thou- 
sand feet or more above the actual producing horizon. 

These geochemical well logs are made up, ordinarily, 
from the cuttings secured in routine drilling, and have 
been of assistance in drilling wells to production at 
depths below those at which they ordinarily would have 
been abandoned. 

NEAR-SURFACE PHENOMENA 

As the escaping hydrocarbons pass through the shal- 
lower sediments, they evaporate ground water, which 
then is replaced by normal sedimentary fluids migrating 
laterally inward. The process, taking place over long 
geologic time, results in the concentration of normal 
ground minerals in and close to the path of the escaping 
hydrocarbons. 

These secondary concentrations of ground minerals 
modify the normal properties of the near-surface sedi- 
ments, and so make possible the use of prospecting 
methods like soil analysis, gravity prospecting, and the 
Eltran (electrical transient). These reconnaissance 
methods block out areas within which significant geo- 
chemical anomalies exist, to be regarded as significant 
only if, by soil analysis, the leakage of significant hydro- 
carbons (Ethane, Propane, and Butane) is established. 

In order to obtain more information than can be 
secured by near-surface prospecting, relatively shallow 
core tests are drilled across the prospect, and geochemical 
logs are made of them. From these logs, a "high-grade" 
spot can be located, where the final, relatively expensive 
test hole to the pay horizon should be drilled. If this 
test well is also geochemically logged, it is possible to 
predict the presence of a petroleum accumulation in the 
untested sediments 500 to 1,000 ft. ahead of the drill. 

conclusions' 

Geochemistry has revolutionized prospecting for 
petroleum. We no longer need look only for structures 
which ma' contain petroleum : we can now explore for 
evidences of the presence and location of the petroleum 
deposit itself. Though a relatively virgin field, geo- 
chemical prospecting has already placed on record sev- 
eral case treatments * where subsequent drilling has 
confirmed, to a remarkable degree, the predictions, made 
on the basis of the original exploration data, as to the 
areal extent of production. 

'Editor's Note: The author cites success at Wasco. Kern 
County, California, bv George F. Gettv, Inc., No. 1 Jannsen, com- 
pleted September 1939 for 1,500 bbl. per day, at a depth of 13,131 
ft., as confirmation of "ETHAXE-PROPANE-BUTANE halo drawn 
from 'One-Eyed' Soilane survey made in Hay 1939, for George F. 
Getty, Inc." (Rosaire, E. E. 39, p. 59.) 



72 



Exploration 



[Chap. II 



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Chapter III 

Early History 



CONTENTS OF CHAPTER III 

Editorial Note: Since the history of the prolific oil and gas regions of southern California may be found in 
Part Three of this bulletin, incorporated with descriptions of the individual fields, the following chapter is 
devoted largely to the known aboriginal record and to the early explorations in the northern coastal region. 



Aboriginal Use of Bitumen by the California Indians, By Robert F. Heizer. 



Page 

._ 74 



History of Exploration and Development of Gas and Oil in Northern California, By Walter Stalder 75 




Fig. 33 F. The famous tar pool or oil seepage of Rancho La Brea, from which Indians secured 
tar and into which many animals, including pre-historic ones of the Pleistocene, became 
entrapped. View looking north from Wilshire Boulevard and La Brea Avenue, Los 
Angeles, taken March, 1915. (The Salt Lake oil field appearing in the background, will 
be described in Part Three of this bulletin.) (Photo by courtesy of the Museum of 
Paleontology, University of California.) 



74 



Early History 



[Chap. Ill 



ABORIGINAL USE OF BITUMEN BY THE CALIFORNIA INDIANS 



By Robert F. Heizer* 



An excellent general treatise on the Old World use 
of bitumen, and the methods of distillation in antiquity, 
has been written by R. J. Forbes (36) ; accounts by H. 
Kohler (13) and the Philadelphia Commercial Museums 
(00) show how widely this substance was known and 
used by the ancients; but apparently no general, pub- 
lished statement on the use of asphaltum by the earliest 
California petrologists, the Indians, is in existence. 

Bitumen, dug from surface land seepages (Eldridge, 
G. H. 01), or collected along the beaches all the way 
from Point Conception to San Diego in the form of 
lumps exuded from submarine seeps, was an important 
adjunct to native technology, serving as a caulking 
material for boats, as an adhesive, or for waterproofing 
baskets. The accompanying map shows various sources 
of native supply which are known to have been exploited 
by the Indians ; these locations have been derived for 
the most part from journals of eighteenth and nine- 
teenth century explorers who saw the Indian cultures, 
now vanished under Caucasian impact, in full operation. 
The Spanish explorer Fages, in 1775, said that "At 
a distance of two leagues from this mission [San Luis 
Obispo] there are as many as eight springs of a bitumen 
or thick black resin which they call chapapote ; it is 
used chiefly by these natives for caulking their small 
water craft, and to pitch the vases and pitchers which 
the women make for holding water." Fr. Pedro Font, 
in 1776, while near Goleta in Santa Barbara County 
wrote ". . . much tar which the sea throws up is 
found on the shores, sticking to the stones and dry. 
Little balls of fresh tar are also found. Perhaps there 
are springs of it which flow out into the sea, because 
yesterday on the way the odor of it was perceptible, and 
today ... the scent was as strong as that per- 
ceived in a ship or in a store of tarred ship tackle and 
ropes. ' ' 

Bitumen was dug out of tar seeps, 
or picked up in lumps on the beaches 
and stored in baskets or large shells. 
The famed La Brea asphalt pits, the 
deathtrap of the ages, occasionally 
caught a luckless Indian whose bones 
and implements along with plant re- 
mains and animal skeletons, have 
been recovered (Merriam, J. C. 14a; 
Hrdlicka, A. 18; Woodward, A. 37). 
Along the Santa Barbara Channel 
the Chumash Indians had perfected 
a wooden canoe made of a great num- 
ber of small planks tied or ' ' sewed ' ' 
firmly together by small ropes. This 
unique canoe (Heizer, R. F. 38) was 
essential to the life of the natives, 
but without asphaltum to caulk the 
plank interstices and binding holes, 
it could not have been constructed. 

The Chumash Indians also used 
bitumen liberally for such purposes 



d 

snd- 



as an adhesive to fix arrowpoints to the shafts; for mem 
ing broken stone vessels or pestles ; as an adhesive for 
stemming pipes with bone mouthpieces; as a mastic or 
setting for inlaying small pieces of shell as decorations; 
and as a filling to rub into incised lines in order to bring 
out the designs in contrastive black color (Harrington, 
J. P. 28, pp. 105-106). Ingenious methods for applying 
the bitumen had been developed by these Indians — a 
long, slender stone was heated and placed in contact 
with the asphaltum lump; this caused the substance to 
flow freely upon the object where it was required. This 
is the same process as our soldering technique. Baskets 
were coated inside with a thin layer of bitumen in this 
manner : lumps of asphaltum were put in the cavity o: 
the basket and with them a number of very hot rounc 
pebbles. The contact of the heated pebbles reduced the 
tar to a fluid state, the basket was shaken round an 
round until an even coating had been applied, the weight 
of the pebbles being sufficient to press the liquid asphalt 
into the interstices of the basket (Rogers, D. B. 29, pp 
396, 398) . Flat stones with a basketry rim firmly attached 
with bitumen served as mortars for grinding seeds. 

The area par excellence of native utilization of 
bitumen seems to have been the Santa Barbara region 
where aboriginal technological attainments were com- 
plex enough to create an extensive demand and wide 
use of the material. The Yokuts tribes of the southern 
San Joaquin Valley were the first exploiters of the 
bitumen springs, the outward evidences of what was 
later to develop into the great Bakersfield petroleum area 
(Gifford, E. W. 26, p. 53). Farther up the central 
valley limited use was .made of asphaltum as an adhesive 
material by the ancient peoples of the delta area; the 
probable sources of supply are shown on the accompa 
nying map (Schenck, W. E. 26, p. 212). 



* Department of Anthropology. Univer- 
sity of California. Manuscript submitted 
for publication January 22, 1940. 

























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LAND SPRINGS OR SEEPS * 
SUBMARINE SEEPS *• 
MISSION SAN LUIS 06ISPO 
TAJICUAS CREEK 

MORES LANDING AT LA PATERA AND 
SANTA BARBARA 
CAflPENTERlA 
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Fig. 34. 



HISTORY OF EXPLORATION AND DEVELOPMENT OF GAS AND OIL 

IN NORTHERN CALIFORNIA 

By Walter Stalder* 



OUTLINE OF REPORT 

Page 
Introduction 75 

Early history 75 

First economic development 75 

The camphene distillers; their interest in California oil 75 

The Scott interests 75 

The first California oil hoom (1865-1866) 76 

Southern California 77 

Central and northern California 77 

The doldrums (1866-1875) and subsequent developments 78 

Natural cas in northern California 79 

Conclusion 80 



INTRODUCTION 

It may be news to many readers that the earliest 
drilling and refining activities in the California gas and 
oil industry were in the central and northern portions 
of our State. In the succeeding pages some of this 
pioneering history is reviewed with the idea of giving 
' its proper position in relation to our early gas and oil 
history. Since space will not permit mention of all 
past activities, the selection as herein made will afford a 
fair picture of progress in this region. 

EARLY HISTORY 

FIRST ECONOMIC DEVELOPMENT 

The first economic use of natural gas in California 
was from the famous Court House well at Stockton, San 
Joaquin County, bored to a depth of 1,003 ft. (1854- 
; 1858). (Weber, A. H. 88, pp. 181-182.) 

As early as 1856 Andreas Pico distilled oil, for use 
in illuminating the San Fernando Mission, from seep- 
ages in northern Los Angeles County. In 1857 Charles 
Morrell, a druggist from San Francisco, erected a dis- 
tilling plant near the maltha seepage at Carpinteria in 
Santa Barbara County and produced illuminants, but 
without commercial success (Hanks, H. G. 84, pp. 293- 
294). 
i 

THE CAMPHENE DISTILLERS; THEIR INTEREST IN 
CALIFORNIA OIL 

Before 1859, when kerosene began to come into wide 
commercial use, camphene was the principal illuminat- 
ing fluid burned in lamps throughout the State. It was 



•Consulting Geologist, San Francisco, California. Manuscript 
, submitted for publication January 25, 1940. In addition to the 
, sources of information cited throughout his paper, Mr. Stalder has 
made frequent reference to the work of his late father, Joseph 
| Stalder; to information furnished bv the late Josiah W. Stanford, 
son of Josiah Stanford of Stanford Brothers ; to information sup- 
plied by Mr. W. W. Orcutt, Vice President of the Union Oil Com- 
' pany of California ; to conversations with "old-timers" at Petrolia, 
', Humboldt County ; to articles in a scrap-book kept by the author 
land his late father since 1S99 ; to data collected during numerous 
visits to the areas discussed, and during contacts with operators of 
| properties : to information supplied by Mr. G. C. Gester, Chief 
Geologist, Standard Oil Company of California; to the records in 
! the Humboldt County Assessor's office ; to records of the Secre- 
, tary of State at Sacramento ; and to data from the Belcher Abstract 
, Company at Eureka. 



originally obtained by distilling turpentine over lime; 
and as early as 1851 a camphene still was erected in 
San Francisco by George Dietz and Company (Mining 
and Scientific Press 60). In 1858 six similar plants 
were operating in the same city (San Francisco City 
Directory 58). George Dietz and Company, Stott and 
Company, Stanford Brothers, and later Hayward and 
Coleman were among the most progressive operators of 
such plants. Their crude turpentine was imported from 
the southern states, and came around Cape Horn. 

After the successful completion of the Drake dis- 
cover}' well in Pennsylvania in 1859 a keen interest was 
manifested in California crude oil for the production of 
kerosene ; as prospects were developed, their production 
found its way to the various camphene stills about San 
Francisco. 

THE SCOTT INTERESTS 

Probably the strongest financial group active in the 
development of a commercial oil industry in California 
was the one headed by Colonel Thomas A. Scott of Penn- 
sylvania. Scott was vice president of the Pennsylvania 
Railroad, and was later the projector of the Texas and 
Pacific Railroad, which he contemplated building from 
Marshall, Texas, to San Diego, California (National 
Cyclopaedia of American Biography 06; Young, J. P. 
12, vol. 2, p. 588). 

During the first oil development in Pennsylvania, 
Andrew Carnegie (National Cyclopaedia of American 
Biography 99), a young associate of Scott, induced 
Scott and J. E. Thomson, president of the Pennsylvania 
Railroad, to purchase with him the Storey farm on Oil 
Creek. Bearing in mind that one year's return from 
this $40,000 investment was more than $1,000,000, and 
that the stock of the company attained a value of 
$5,000,000, it is easy to understand Scott's interest in 
the purchase of prospective oil lands in connection with 
his early plans for a railroad to California, and his send- 
ing an expedition (1863-1864) to buy gold lands in 
Arizona and oil lands in California (The Road 75). 
Professor Benjamin Silliman, Jr. (65; 65a; 65b), of 
Yale University, came to California, and reported on 
certain lands in connection with this enterprise. As a 
result, the Scott group purchased the following ranchos : 
Simi (113,000 acres), Las Posas (26,500 acres), San 
Francisco (48,000 acres), Calleguas (10,000 acres), 
Colonia (45,000 acres), Canada Larga (660 acres), and 
Ojai (16,000 acres) ; a large paft of the town of San 
Buenaventura; all in what is now Ventura County; 
and also some 12,000 additional acres located in Los 
Angeles and Humboldt counties — making a total of 277,- 
000 acres. To develop these holdings, the Philadelphia 
and California Petroleum Company, the California 
Petroleum Company, and the Pacific Coast Petroleum 
Company were formed (Gidney, C. M. 17, vol. 1, pp. 
358-359) ; to manage these California holdings, Scott 
sent a progressive young attorney, Thomas R. Bard, who 
arrived in California in January, 1865. 



76 



Early History 



[Chap. Ill 



The Scott group became interested in Humboldt 
County oil lands through J. W. Henderson, who, while 
in that northern county in 1864, secured some samples 
of seepage oil, high in illuminants and closely resembling 
Pennsylvania oil (Semi- Weekly Standard 01). Hender- 
son returned to Humboldt County as manager of the 
Scott interests there, and proceeded to purchase land 
with Indian scrip and school warrants. This land pur- 
chasing was conducted in cooperation with Levi Par- 
sons (Appleton's Cyclopaedia of American Biography 
88) who was evidently the person through whom Hen- 
derson brought about Scott's activities in Humboldt 
County. The surface of these lands was later sold, but 
the mineral rights were retained (Humboldt Times 19). 

As early as November 1861 there is mention of a 
well being drilled on the Davis Ranch in Humboldt 
County, after the manner of artesian wells. It appears 
to be the earliest well so sunk for oil in California (Min- 
ing and Scientific Press 61). 

THE FIRST CALIFORNIA OIL BOOM (1865-1866) 

In 1865 the first California oil boom was born. People 
became interested not only in the crude seepage oils of 
Humboldt, Colusa, Santa Clara, and San Mateo coun- 
ties, but also in the asphalt seepages and bituminous 
residues occurring in Mendocino, Marin, Contra Costa, 
Santa Clara, and Santa Cruz counties. In the south the 
large bituminous seepages in Ventura (formerly a por- 
tion of Santa Barbara), Santa Barbara, Kern (formerly 
Tulare) and Los Angeles counties received the most atten- 
tion. It should be remembered that the oil industry was 
at that time in its infancy, and that very little was 
known of the laws governing the accumulation of gas 
and oil. Consequently, the tendency was to carry on 
operations near seepages or near oil-sand outcrops. 
Trenches, pits, tunnels, shafts, and shallow wells drilled 
either with spring poles or with light steam-driven 
engines were the instruments of production. 

The Union Mattole Oil Company, which caused much 
of the Humboldt County excitement in 18 c i5, filed its 
articles of incorporation with the Secretar}' of State in 
Sacramento March 25, 1865. It had as its first three 
directors Thomas Richards, William Ede, and Edward 
Bosqui, all business men of San Francisco (San Fran- 
cisco City Directory 66; 67). Its first well was located 
on the picturesque North Fork of the Mattole River in 
Sec. 30. T. 1 S., R. 1 W., H. Drilling was inaugurated 
promptly, and on June 10, 1865, the Humboldt Times 
carried the following item : 

"The First Shipment of Coal Oil from Humboldt County. On 
Wednesday last, Mr. F. Francis of Femdale brought into town 
six packages of from 15 to 20 gallons each of coal oil taken from 
the well of the Union Mattole Oil Company. This will go to San 
Francisco by the present trip of the steamer and is the first ship- 
ment of crude oil from the oil regions of this county." 

The first shipment reached San Francisco June 12, 
1865, and credit for its refining goes to Stanford 
Brothers, whose camphene still was located at the north- 
east corner of Chestnut and Taylor streets. The product 
was sold for $1.40 per gal. (San Francisco Bulletin 65; 
65a). This appears to be the first oil, from a drilled 
well in California, to be distilled and sold on the market. 

The Stanford brothers directly interested in the cam- 
phene plant were Josiah, A. P., and Charles. Josiah 
Stanford, however, was the moving spirit in the organi- 
zation (San Francisco City Directory 66a). 



TABLE I— WELLS DRILLED (1865-1866) IN MATTOLE, 

BEAR RIVER, AND OIL CREEK DISTRICTS OF 

HUMBOLDT COUNTY, CALIFORNIA* 







Local 


on 






Nam? of well 


Sec. 


T. 


II Maid 


Remarks 


Scott and Parsons** 


15 


1 S 


2 VV 


H 


Also known as Noble well, 
J. VV. Hendeison, supt.-mgr. 


Sutter and Allen** 












{5 wells)- _ 


29, 30 


1 S 


2 VV 


H 


Located in McNutt Gulch: 
Wm. Muldrow, supt. 


North Fork** 


25 


1 S 


2 W 


H 


Capt. VV. C. Martin, supt. 


Union Mattole Oil 












Co.** (2 wells. 1 












pit) 


30 


1 S 


1 W 


H 


Mr. Bosqui. supt. 

Reported depth 1.170 ft., deepest test in 


Irwin Davis 


33 


1 S 


2 W 


H 












county in 1866. 


Paragon 


30 


1 S 


1 W 


H 


T. C. Duff. supt. 


Brown and Knowles 


25 


1 S 


2 W 


H 




Fonner (3 wells) 


28.33 


2 .S 


1 VV 


H 




Mattole Pet. Co 










Located North Fork of North Fork of 
Mattole River 


Jeffrey 


28 


1 S 


2 W 


H 




Buckeye _ 










Loeated on Conklin Creek; Capt. W. C. 
Martin, supt. 


Hawley 










Located on Bear River; Mr. Wattles, 
supt. 


Davis 










Located on Bear River 


Johnson Farm 










Located on Bear River; Mr. Kirk. supt. 


Fo'tuna - _ 










Located on Bear River 


Oil Creek Pet. Co. 












(2 wells) 


22, 32 


2 N 


2 W 


H 


Located on Oil Creek, at head of its 
northeast branch; Capt. Knypthausen 
Greer, supt. 






•Data from dies of Humboldt Times. 1865-66-67. and Mining and Scientific Press, 
1865-66-67. 
'♦Shipped oil to San Francisco. 

On Thursday, August 24, 1865, the steamer Del 
Norte left Eureka with 16 bbl. and 27 half barrels of oil 
from the Union Mattole Company, and several "pack- 
ages" ranging from five gallons to a barrel each from 
the Noble (Scott and Parsons) well and from the Sutter 
and Allen well. On September 9, 1865 there were 40 
"packages" of petroleum at Centerville awaiting trans- 
portation to Eureka for shipment to San Francisco 
(Humboldt Times 65; 65a). Other shipments were 
made later. 

An analysis of oil from the well of the Sutter and 
Allen Company was made by Rowlandson (Humboldt 
Times 65a) : 

Material Per cent 

Good burning oil 77 

Amber colored light machine oil 5 

Dark colored machine oil 4 

Loss and residue 14 

100 

None of the wells actively producing in Humboldt 
County during 1865 and 1866 was over 260 ft. deep.* 
The Union Mattole well No. 1 was the best, and evidently 
it had a strong appeal to the Stanford Brothers, for they 
entered the market for Union Mattole stock and secured 
control (Mining and Scientific Press 66d). In 1867 
they drilled a well to the depth of 1,003 ft. beside Union 
Mattole well No. 1, but it was not successful (Irelan, W. 
88b, p. 197). The casings of both wells still protrude 
from the ground, and oil can be dipped from No. 1. 

All of the producing wells in Humboldt County soon 
developed troubles, mostly with caving, water, crooked 
holes, or too small production. Pennsylvania oil took a 
great drop in price which affected California prices. 
Transportation of oil from the wells was expensive 



* The Mining and Scientific Press, Aug. 18, 1866, gives depth of 
North Pork well as 260 ft. The Mining and Scientific Press, Dec. 
2, 1865, p. 345, gives depth of three Union Mattole wells as 135 ft.. 
167 ft., and 20 ft, respectively. Mining and Scientific Press, Dec. 
16, 1865, p. 369, gives depth of oil production in Noble (Scott and 
Parsons) well on Joel Flat as 210 ft. The Humboldt Times, Sept. 
7, 1865, gives depth of Sutter and Allen wells in McNutt Gulch as 
173 ft., 125 ft., and 130 ft., respectively. These were the producing 
wells of the time. 



Exploration in Northern Caliporni a — S t a l d e r 



77 



(Semi-Weekly Standard 01 ; Leach, F. A. 17, pp. 98-99) ; 
oil was shipped in small containers on mule-back to 
Centerville, a distance of 30 miles ; there it was loaded 
into trucks and hauled an almost equal distance over 
bad roads to Eureka ; from Eureka it was transported by 
steamer 216 miles to San Francisco. To add to all these 
difficulties, the United States Government, under date 
of March 17, 1865, sent out orders to withhold Hum- 
boldt County oil lands from disposal, making most titles 
questionable. Under these accumulated discouragements, 
t the first California oil boom died in 1866 (Ball, M. W. 16, 
pp. 59, 60; Irelan, W. 88, p. 199). Attempts were made 
in 1894, 1899, 1900, 1907, 1921, and 1935 to bring about 
better production with deeper wells, but without suc- 
cess. 

SOUTHERN CALIFORNIA 

Contemporaneous with the Humboldt County activ- 
1 ity of 1864, 1865, and 1866, was the attention given other 
oil-seepage areas of California. The Philadelphia and 
California Petroleum Company (Scott interest) made 
application for a license to distill oil from springs (San 
Jose Mercury 65). The Scott interests, under the man- 
1 agement of Thomas Bard, also drilled six exploratory 
wells on the Rancho Ojai on the north flank of Sulphur 
Mountain in Ventura County (Oil Weekly 21). 

The first five wells were not successful, but the sixth 
became a producing well in 1866, making a settled pro- 
duction of about 20 bbl. per day. This well was shut 
down because there was no market for the oil. The Scott 
well in Humboldt County was also shut down because 
: of caving and small production. Over $200,000 was 
spent bv this group ; however, thev owned their lands 
and could wait (Gidney, C. M. 17, 'vol. 1, pp. 358-359). 

The former camphene distillers of San Francisco also 

looked to the south for a source of crude oil. Charles 

Stott exploited oil seepages and started his own refinerv 

|in Santa Paula in 1866 (Hanks, H. G. 84, p. 295). Hay- 

!ward and Coleman and Stanford Brothers also exploited 

seepages and drove tunnels into the flank of Sulphur 

: Mountain, and obtained a production of a few barrels 

of oil per day. This, together with oil purchased from 

others, formed the source of the crude supply for their 

ISan Francisco refineries. 

Colonel Thomas Scott died in 1881. Prior to that 
jdate Hardison and Stewart, two enterprising Pennsyl- 
vania operators, active in Ventura and Los Angeles 
counties, built the toundation for a successful oil busi- 
ness after many disappointments. Thomas R. Bard, to 
whom fell the task of disposing of the Scott interests, 
[brought about a combination of the Hardison and 
Stewart interests and certain of the Scott oil holdings 
as the Union Oil Company of California, incorporated 
]in 1890 (Petroleum Register 37). 

E. Benoist was a student of early California refining 
| problems. He had an oil laboratory on Third Street in 
San Francisco (Mining and Scientific Press 65 p.). With 
'Stephen Bond as a partner, he attempted to drill a well 
at Buena Vista in Kern County (then Tulare County) 
at the east end of the present McKittrick field. The 
attempt resulted in failure when the drilling bit became 
hopelessly stuck in the hole. Benoist and Bond did 
^btain oil, however, from pits in the same region (Sees. 
|19, 20. 29, T. 30 S., R. 22 E., M. D.). These pits were 



usually about 20 ft. deep, 5 ft. wide, and 8 ft. long; 
each produced in 24 hours about 300 gal. of crude oil 
containing 40% light and 50% heavy or lubricating oil. 
The claim was worked from February 1864 to April 
1867, when the local demand was fully supplied, and 
the low price of oil made its preparation for the San 
Francisco market unprofitable. (Browne, J. R. 68, p. 
263; Hanks, H. G. 84, p. 296.) 

CENTRAL AND NORTHERN CALIFORNIA 

In 1861 workmen discovered an oil seepage while cut- 
ting saw logs for Moody's mill in Moody's Gulch near 
Lexington in Santa Clara County (Mining and Scien- 
tific Press 61a). 

Tn April 1865 the Santa Clara Petroleum Company 
put down a well in the Moody Gulch region, and the 
Shaw and Weldon Petroleum Company sank a shaft that 
"struck a vein of finest quality" at 30 ft. (San Jose 
Mercury 65a). During the same year the Pacific Petro- 
leum Company was incorporated to operate near Lex- 
ington (San Jose Mercury 65b) ; and in October 1865 
a shipment of 60 gal. of oil was made from a Lexington 
well to San Francisco (San Jose Mercury 65c). The 
Alta Californian of October 11, 1865, tells of a shipment 
of oil from Lexington to New York, and of a 100-gal. 
shipment to San Francisco, to show the excellent char- 
acter of the oil. 

The crooked McLeran well, which reached a depth of 
470 ft., cut several oil sands, but no water sands. 
Although five barrels of oil could be pumped from the 
well each morning, drilling was suspended (San Jose 
Mercury 66). By this time (1866). the fact that oil was 
present in the field had been demonstrated, but it 
remained for more experienced operators to develop it. 

In 1864 and 1865 works were erected at the bitu- 
minous oil seepages on the Sargent Ranch (Sec. 36. 
T. 11 S., R. 3 E., M. D.) in Santa Clara County to dis- 
till coal oil. The operation was successful for a time, but 
eventually halted (Hanks, H. G. 84, pp. 288-289). 

On the Medar ranch at Santa Cruz, the Santa Cruz 
Petroleum Company erected six retorts in 1864 to con- 
vert the asphaltum found there into coal oil and lubri- 
cating oil, grease, etc. (Alta Californian 64). Although 
the refinery itself was not a success, the output of bitumi- 
nous rock has been fairly consistent since that early date. 
The same company also drilled a well for oil, but, like 
all later prospect wells in this neighborhood, it was not 
successful. (Browne, J. R. 68; Yale, C. G. 94; 00; 
Walker, D. H. 07; 07a; Boalich, E. S. 11; Bradley, 
W. W. 15; Symons, H. H. 28). 

The Point Arena Petroleum Mining Company, organ- 
ized in 1864, erected a plant near the Point Arena wharf 
in Mendocino County to convert bituminous rock to coal 
oil, but this operation was a failure.* Wells drilled later 
(1907-1009 and 1918), none of which were successful, 
all reported penetrating tar sands from which the fluid 
could not be pumped because of its viscosity (Mining 
and Scientific Press 64). A deep well drilled in 1929 
bv the Twin States Oil Companv less than ^-mile south 
oif the Port of Point Arena (Sec! 14, T. 12 N., R. 17 W., 
M. D.) was abandoned in 1932. 



* Data collected in 1910 from the late Porter O'Neal and Thomas 
O'Neal of Point Arena, California. 



78 



Early History 



[Chap. Ill 



J. D. Whitney (65, p. 12), in his report on the 
geology of California, mentions that a well was bored in 
1862 to a depth of 87 ft. on the west side of San 
Pablo Creek about four miles slightly south of east of 
the town of San Pablo, Contra Costa County. This 
87-foot well is apparently the second to be bored for oil 
in California. Whitney also mentions the erection of 
works at this locality for the purpose of distilling the 
bituminous matter in the out-cropping rocks, and any 
oil from the well. The work was evidently not profitable, 
however, for it was discontinued. 

Late in December 1864 the Adams Petroleum Com- 
pany was formed to drill in the SW4, Sec. 15, T. 1 N., 
R. 1 E., M. D., Contra Costa County, where they 
obtained a greenish oil, but in too small amounts to be 
profitable. All efforts at this place and elsewhere in 
Contra Costa County have produced no commercial gas 
or oil ; but gas and oil showings have been manifest in 
several wells (Mining and Scientific Press 64a; 65q). 

In 1865 the Bolinas Petroleum Company began opera- 
tions in Arroyo Hondo on the Bolinas grant in Marin 
County, being attracted by the asphalt seepages and out- 
crops about that part of the Point Reyes peninsula. 
This and a later attempt about 1902 to secure commercial 
oil production were failures (Hanks, H. G. 84, p. 295; 
McLaughlin, R. P. 14, p. 473). 

In regard to oil seepages in San Mateo County, the 
Mining and Scientific Press for May 6, 1865, p'. 279, 
states : 

"We understand that oil has been discovered on Bell's ranch 
about fifteen miles below Halfmoon Bay where oil had previously 
been discovered on Purissima Creek." 

A tunnel was run on Purisima Creek and some oil 
obtained, and a well at Bell vale found a little oil, but not 
in commercial quantity. Later developments at Purisima 
Creek resulted in the establishment of a small, high- 
gravity oil field. 

Along Bear Creek, chiefly in T. 15 N.. R. 5 W., M. D. 
in Colusa County, several wells were drilled (1865-1866) 
near outcropping oil sands or seepages of high grade oil 
not unlike that of Humboldt County. None of these 
wells was successful ; but wells drilled later, to the east 
in T. 15 N., R. 4 W., M. D., (McLaughlin, R. P. 14, pp. 
441-442) and two wells drilled bv the Continental Oil 
Company (Sec. 31, T. 18 N., R. 4 W., M. D.) north of 
Sites (1925-1926) afforded information that had a bear- 
ing on subsequent developments in the Sacramento Val- 
ley at Sutter (Marysville) Buttes. 

Dexter Cook was an industrious laborer, who built 
many of the stone walls about Sutter Buttes in Sutter 
County, and dug many water wells for the ranchers.* 
On the south flank of these Buttes in the NW} Sec. 36, 
T. 16 N., R. 1 E., M. D., is a spot where the rocks have 
been slightly clinkered by the burning of escaping 
natural gas. This exposure is not unlike the clinkered 
rocks that frequently accompany coal outcrops in the 
Rocky Mountains. Cook decided to explore at this place 
for coal. In February, 1864, he started a shaft, and from 
the bottom drifted a tunnel. Gas was struck, and becom- 
ing ignited, exploded. Cook was more frightened than 
injured, but during the remainder of his life kept in 
closer contact with the occupation that he knew (Watts, 

•Data from James D. Carroll of West Butte, and the late 
I-ewis Stcililnian of Sutter. California. 



W. L. 94, p. 9). His findings, however, afforded part of 
the information from which resulted the commercial gas 
development at the Buttes. 

THE DOLDRUMS (1866-1875) AND SUBSEQUENT 
DEVELOPMENTS 

Failing to obtain a large high-grade crude oil supply 
with which to compete with cheap Pennsylvania oil that 
was arriving in San Francisco at lower and lower prices, 
the refiners in San Francisco and those located closer to 
the southern sources of crude asphalt oils found increas- 
ingly greater difficulty in keeping their stills going with 
California oils. In this relation, J. Ross Browne (68, pp. 
261-262) wrote: 

"Between 1865 and 1867, Haywood and Coleman, a firm in the 
oil business in San Francisco, made 40,000 gallons of illuminating 
oil from springs of petroleum near Santa Barbara, but suspended 
operations in June 1867 because imported oil was selling for 54* 
to 55c per gallon, a price so low as to render the manufacture 
unprofitable owing to the high prices of cases to contain It, trans- 
portation and labor. 

"Stanford Brothers have also expended capital and labor In 
efforts to manufacture oil from California petroleum and have 
succeeded so far to make oils but not with profit. Up to July 1867, 
this firm made 100,000 gallons of illuminating oil and nearly an 
equal quantity of lubricating and have been making about 20.000 
gallons of illuminating oil per month since. Their works are still 
in operation. This firm purchased their crude oils from several 
localities but obtain their chief supply from tunnels and pits near 
San Buenaventura." 

In November, 1869, Stanford Brothers sold their 
business and plant to Allyne and White. John W. 
Allyne was a nephew of the Stanford brothers and had 
acted as their bookkeeper. This new firm imported its 
crude oil from Pennsylvania, opened quite a trade in 
kerosene throughout the State, and later went into the 
manufacture of tree sprays. In 1882, after the Califor- 
nia oil industry had demonstrated that it was no longer 
an uncertainty, the Standard Oil Company entered the 
State, bought the business of Allyne and White. This 
stopped operations at the plant that refined the first oil 
from the historic Union Mattole well. 

After 1866 the oil industry of California was in the 
doldrums for several years. It remained for the Southern 
Pacific Railroad to really bring success by solving the 
transportation problem for the prospective oil district 
through which it passed between San Francisco and Los 
Angeles. In 1876 it was completed through Newhall, 
Los Angeles County (San Francisco City Directory 77, 
p. 22; 78, p. 20). Prior to that date, oil had been 
obtained in this neighborhood mostly by means of pits 
near seepages. In 1875 three shallow wells were drilled 
in Pico Canyon with spring poles, and actual develop- 
ment with steam machinery was begun in 1877 by men 
with a wide practical experience in the oil business. Oil 
was rapidly developed near Newhall, both in Los Angeles 
and in Ventura counties. The founders of the Pacific 
Coast Oil Company acquired a small refinery at Newhall 
in 1876, and built a larger one at Alameda Point in 
Alameda County after the incorporation of the com- 
pany, September 10, 1879 (Hanks, H. G., 84, p. 300, et 
seq.). Hardison and Stewart, the two Pennsylvania 
operators, were also active in Los Angeles and Ventura 
counties at this time, and had spent $130,000 in prospect- 
ing. Their Mission Transfer Company soon became an 
influential factor in the development of these two south- 
ern counties (McLaughlin, R. P. 14, p. 369). 

The Pacific Coast Oil Companv had as its officers C. 
N. Felton, President, D. G. Scofieid, Auditor, and L. D. 
Fisk, Secretary. The offices were at 402 Montgomery 



Exploration in Northern Californi a — S talder 



79 



Street, San Francisco (Munro-Fraser, J. P. 83, p. 409). 
This company operated until 1902, when it was absorbed 
by the Standard Oil Company of California. 

In 1878, C. N. Felton, after his successful start in Los 
Angeles and Ventura counties, moved with P. C. McPher- 
son, a successful Pennsylvania operator, from Newhall to 
Moody Gulch in Santa Clara Count}-. In one of the wells 
alreadv drilled in the field, McPherson obtained for a 
time, 60 bbl. of 46° to 47° B. oil from a depth of 700 ft. 
This oil was sent to the Newhall refinery as the plant at 
Alameda Point had not yet been constructed. In addi- 
tion, the field was on the railroad, thus facilitating such 
shipments. Ten wells were drilled by the Santa Clara 
Petroleum Company (1879-1888). These wells were 
drilled to depths varying between 800 and 1,615 ft., and, 
as a rule, penetrated several sands. Only five of the 
wells were really successful ; they had initial productions 
of from 10 to 100 bbl. per day. In 1884 this oil was being 
shipped to the Pacific Coast Refinery at Alameda Point, 
but in 1888 it was being sold to the San Jose Gas Works 
for $3.00 per bbl. The production to 1886 was reported 
as 80,000 bbl. (Foote, H. S. 88, pp. 164, 165; Hanks, 
H. G. 84, p. 295). This small field, which is still being 
developed, has since that time been an intermittent 
producer. 

The Sargent Ranch field (Sec. 36 and vicinity, T. 11 
S., R. 3 E., M. D.) on the line of a railroad in Santa 
Clara County, also received new attention. In 1884 
asphaltum from tha seepages on Tar Creek was being 
cleaned and shipped to San Francisco; in 1888 some of 
this same material was being used in the gas works at 
Gilroy. Drilling is reported to have been started in 1886. 
At the time of the writer's last visit to this field (1920), 
nine wells with an average depth of about 1,200 ft. were 
being operated by the Watsonville Oil Company with a 
total output of 55 bbl. per day. (Hanks, II. G. 84, p. 
289; Irelan, W. 88c, p. 548; McLaughlin, R. P. 14, 
p. 470). 

In 1884 the field at Tunitas Creek in San Mateo 
County was visited by the State Mineralogist; by this 
time several wells had been sunk, and from one of them 
(O'Brien Ranch) some oil had been pumped (Good- 
year, W. A. 88, p. 100). The Purisima Creek region 
also received attention, and from a limited area a few 
small wells were brought in at the rate of 10 to 20 bbl. 
per day; but this production declined rapidly. About 
20 wells were drilled here, most of them to depths of 
700 or 750 ft. where oil sands occur.* The oil, which 
is very light, was refined by a Mr. Knapp at Halfmoon 
Bay prior to 1908; it was afterward shipped out in 
drums, and by 1915, production had dwindled to one 
carload per year.** In this region the Shell Oil Com- 
pany, the Traders Oil Company, and later the Wilshire 
Oil Company drilled deep wells, but without success. 
NATURAL GAS IN NORTHERN CALIFORNIA 

After the discovery of natural gas at Stockton (1854- 
1858) many wells in the region encountered gas in drill- 
ing for water. Much of this gas was used for manufac- 
turing and domestic purposes. In 1885 the Standard 
Gaslight and Fuel Company was formed at Merced with 
the object of developing natural gas in the San Joaquin 

•Data from S. A. Guiberson. Jr., who drilled five of the wells 
on Purisima Creek. 

••Personal communication from J. W. Crosby, secretary of the 
former Ocean Shore Railroad, to Mr. F. W. Bradley. May 15. 1915. 



Valley. Operations were commenced in the spring of 
1886, at Stockton. In the summer of 1886, the Califor- 
nia Well Company was organized at Stockton for the 
same purpose, and began operations immediately. The 
Crown Mills well, drilled in 1886, developed a gas flow 
of 18,000 cu. ft. per 24 hours, from a depth of 1,220 ft. 
Lighting of the plant required 6,000 cu. ft., and the 
remainder was used for fuel. The city gas supply of 
Stockton has been almost continuously augmented by 
natural gas from water wells. The greatest yearly pro- 
duction was 313,392 M. cu. ft. in 1910, valued at $159,- 
451. The recorded production of gas for San Joaquin 
County from 1899 to 1916 was valued at $2,284,635. 
The producing wells varied in depth from 1,000 to 2,000 
ft. Gas and water were always produced together. 
(Symons, H. H. 35, pp. 220-221). 

In 1891 gas was discovered in water wells near Sac- 
ramento. This was also put to use. Production in 1913 
was valued at $33,000, and from 1899 to 1916, at $758,- 
073. (Symons, H. H. 35, pp. 208-209.) 

Two successful gas wells have been developed in 
Humboldt County. One, drilled at Briceland in Sec. 18, 
T. 4 S., R. 3 E., H., has been supplying that hamlet with 
natural gas since May 1894.* The Texas Company now 
has a 500,000 cu. ft. gas well shut in on Tompkins Hill 
in Sec. 22, T. 3 N., R. 1 W., H, and at the present time 
is drilling another in the same section. The Texas Com- 
pany operation, however, is in the Humboldt Basin, 
which has no connection with the earlier areas of explo- 
ration. Work has also been proceeding on Joel Flat near 
the site of the old Scott and Parsons well, with results to 
date about equal to those obtained by Scott and Parsons. 

In 1901 the Rochester Oil Company drilled a well 
to a depth of 1,820 ft. in NE} Sec. 24, T. 5 N., R. 1 W., 
M. D., Solano County, in the vicinity of surface gas 
blows (Sees. 11 and 14, T. 5 N., R. 1 W., M. D.). The 
gas yield of 20 M. cu. ft. was used to supply the towns 
of Suisun and Fairfield, for a number of years. Between 
1908 and 1913 the value of the gas produced was $61,311 
(Symons, H. H. 35, p. 237 ; Vander Leek, L. 21, p. 55). 

Near Petaluma in Sonoma County, prospecting for 
gas and oil has been carried on since 1909. Some strong 
gas blow-outs occurred in drilling wells, but no produc- 
tion was made until Herbert N. Witt and associates, 
drilling on the Ducker Ranch in Lot 269 of the Peta- 
luma Rancho survey, found oil at 900 ft. with an initial 
flow of 20 bbl. per day of 19° B. oil.** This oil was sold 
to the Shell Oil Company for use in drilling deeper 
wells, which encountered a great thickness of basalt. The 
wells were then abandoned (Laizure, C. McK. 26b, p. 
354). About 5,000 bbl. of oil were reported from this 
well ; 3,000 bbl. were sold to the Shell Oil Company for 
$1.00 per bbl. and the remainder used in drilling.** 

The first northern California high-pressure water- 
free gas well to be brought in was The Buttes Oilfields, 
Inc., Sophie Davis No. 1, in Sec. 36, T. 16 N., R. 1 E., 
M. D., at Sutter (Marysville) Buttes, Sutter County. 
This well was located } mile southeast of the spot where 
Dexter Cook encountered gas in his shaft of 1864. Well 
No. 1 was brought in at 2,727 ft. under a pressure of 
1,420 lb. per sq. in., February 9, 1933, and gauged 3,425 

• Communication from Albert Etter of Ettersberg with data 
from Mrs. J. W. Bowden, who taught school at Briceland when 
gas was first used. 

•• Data from Herbert N. Witt. Mining Engineer. 



80 



Early History 



[Chap. Ill 



M. cu. ft. initial production. At the present time, well 
No. 6 is being drilled. The output is being sold to the 
Pacific Gas and Electric Company to supply domestic and 
manufacturing needs in nearby areas. A condensate 
resembling lubricating oil accompanies the gas. Between 
13,500 and 20,000 acres are considered tentatively 
proven. This field was discovered by the application of 
geological methods (Stalder, W. 32, pp. 361-364). 

The Pure Oil Company in November 1934 brought in 
their well No. 1 (Sec. 7, T. 10 S., R. 14 E., M. D.) in 
Madera County, and opened up production in the Chow- 
chilla gas field. The well is 8,030 ft. deep and gauged 
15,000 M. cu. ft. initial production. The gas contains 
impurities that reduce its heat value. This field was 
located with a seismograph (Petroleum World 38a, 
p. 134). 

The Tracy gas field (Sees. 15, 22, 23, T. 2 S., R. 5 E., 
M. D.) in San Joaquin County was brought in by well 
No. F. D. L. 2 of the Amerada Petroleum Company 
August 12, 1935 and gauged 35,000 M. cu. ft. from a 
depth of 4,063 ft. The gas is sold to the Pacific Gas 
and Electric Company. The proven area consists o" 
about 350 acres. The Tracy field was discovered with 
the seismograph (Petroleum World 38a, p. 134). 

The McDonald Island gas field was discovered by the 
Standard Oil Company of California with their McDon- 
ald Island Farms well No. 1 (Sec. 25, T. 2 N., R. 4 E., 
M. D.) at 5,227 ft. June 2, 1936. Initial production was 
26,647 M. cu. ft. The proven acreage is 5,000. This 
field is a seismograph discovery, and is located on McDon- 
ald Island, San Joaquin County (Petroleum World 38a, 
p. 134). 

The Rio Vista gas field was brought m June 1936 
by Amerada Petroleum Corporation with their Emigh 
No. 1 well in Sec. 35, T. 4 N., R. 2 E., M. D., Solano 
County. The initial production was given as 81,250 M. 
cu. ft. per day. The depth of the well is 4,410 ft. A 
gasoline condensate accompanies the gas. In 1938, some 
5,000 acres were considered proven, but the field has 
since been extended southeast into Sacramento County, 
and its limits are not yet known. There are 22 producing 
wells at present, This is the most productive straight gas 
field in California. Knowledge of the gas blow-outs that 
occurred in Sees. 11 and 14, T. 5 N., R. 1 W., M. D., and 
some scattered rock exposures about this field, suggested 
its presence, which was more definitely verified by use of 
the seismograph (Petroleum World 38a, p. 134). 

Fairfield Knolls gas field in Yolo County was dis- 
covered November 6, 1937, when Standard Oil Company 
of California brought in well No. 1 (NE£, Sec. 32, T. 9 
N, R. 1 E., M. D.). This well had been drilled to 5,181 
ft. and plugged back to 3,700 ft, It is rated as a 3,500 M. 
cu. ft. gasser for conservative delivery. Prior to drilling 
in this field, Standard had drilled on a structure in the 
Dunnigan Hills. Their Peter Cook well No. 1 was drilled 
to 5,009 ft. and abandoned October 27, 1937, because the 
gas sands were too tightly cemented to yield commercial 
gas. Both the Fairfield Knolls and Dunnigan Hill areas 
are topographically high. Structure was verified by use 
of the seismograph. 

The Potrero Hills gas field of Solano County was 
brought in by the Richfield Oil Company with their 
Potrero Hills No. 2 well (Sec. 10, T. 4 N., R. 1 W., 
M. D.) completed in December, 1938, at a depth of 3,265 



fi * 



ft., with an initial production of 5,000 M. cu. ft. This 
structure had previously been prospected to a depth of 
3,128 ft. by the Honolulu Oil Corporation in 1920. The 
field was discovered through geologv. 

Ohio Oil Company Willard well No. 1 (Sec. 18, T. 
20 N, R. 2 W., M. D.), in Glenn County, blew in January 
7, 1938, out of control, from just below 4,400 ft. The 
derrick was engulfed and went out of sight. A crater 
150 ft. in diameter was formed, and much equipment 
was lost. The crater spouted gas, mud, and salt water 
for over two weeks. 

To date no prolific oil fields have been discovered in 
northern California. Along the Ukiah-Tahoe highway 
in Sec. 31, T. 15 N, R. 4 W„ M. D., Colusa County, is 
an outcropping porous sandstone well impregnated with 
petroleum. About 1925 a shallow well drilled into it 
produced a very small amount of oil. Later the Calvada 
Oil Company drilled three shallow wells down the dip 
of this steeply tilted sand ; they also obtained small^. 
amounts of oil. (In the Rumsey Hills of Yolo and Colusa 
counties, this same sand is calculated to underlie the\ 
large Nigger^Heaven_dQjne at a depth somewhere between fr 
7,5P^-an4jL l 039HS^n:n August, 1930, George F. Getty, 
Inc., started a well on this structure (Sec. 22, T. 12 N., 
R. 3 W., M. D.) which was later taken over and drilled 
deeper by the Nigger Heaven Dome Oil and Gas Com- 
pany. It reached a depth of 6,764 ft. before drilling was 
suspended in 1934. Water, gas, and oil globules now 
flow from it. 

CONCLUSION 

While progress in central and northern California 
has been slow, the rapid strides that have been made in 
southern California are well known. It is now possible 
to drill a well to 10,000 ft. in almost the same time that 
it took the pioneers of 1865-1866 to drill 250 ft. In the 
San Joaquin Valley many new fields are being found at 
depths of 10,000 ft. or over. When the oil industry 
actively returns to the northern areas and seriously 
attacks the many problems there presented with well- 
located and scientifically drilled wells to depths now 
within range of the drill, it is trusted that the work 
begun by the early pioneers will at last be completed 
and in addition to present large commercial gas fields, 
more definite data will be available regarding oil as well. 




~ -' - , £*&, 





H 



Fig. 35. From the historic Union Mattole Oil Company well (Sec. 
30, T. 1 S., R. 1 W., H.M.) early in June 1865 the first ship- 
ment of crude oil was made to San Francisco. Although oil 
from pits had been refined in California, this was the first 
drilled well in this state to send oil to the refineries in San 
Francisco and the product sold to the trade. The above photo- 
graph taken in May, 1935, indicates that oil can yet be dipped 
from the hole. (Photo and caption by Walter Stadler, May, 
1935.) 



GEOLOGIC FORMATIONS AND ECONOMIC DEVELOPMENT OF THE OIL AND GAS 

FIELDS OF CALIFORNIA 



Part Two 

Geology of California and the Occurrence of Oil and Gas 

Editorial note: 

PART TWO represents the second of four divisions of Bulletin 118, and is intended, first, to outline 
the broader features of the geology of California and to indicate their significance and relationship to the 
mineral industry ; second, to review the stratigraphic and structural history of the State, more especially of the 
better-known parts of the coastal region; third, to present pertinent and well-established conceptions of the com- 
plicated stratigraphic correlation of the upper Mesozoic and Cenozoic sedimentary rocks involved in the exploration 
' for oil and gas; and fourth, to discuss the processes of oil generation and accumulation. It is hoped that the many 
' accompanying charts and maps, explicitly prepared for frequent reference, together with carefully chosen photo- 
i graphs of characteristic fossils, may materially assist geologists in future exploration not only for new deposits 
i of oil and gas, but for all manner of valuable mineral resources. A better understanding of the extremely com- 
i plex history and structure of the sedimentary rocks of California is in itself an accomplishment of lasting impor- 
tance to the whole scientific, engineering, and industrial world. Since Part Two is an assemblage of articles 
written by individual authors, it should not be expected that all interpretations will be found in perfect harmony. 
The variety in point of view should lend flavor to the reading of factual details. 

The following chapters are included in PART T WO : 

Page 

CHAPTER IV 

Introduction to the Geology 82 

CHAPTER V 

Geologic History and Structure 98 

CHAPTER VI 

Paleontology and Stratigraphy 164 

CHAPTER VII 

Occurrence of Oil 208 






Chapter IV 

Introduction to the Geology 



CONTENTS OF CHAPTER IV 






Page 
Geomorphic Provinces of California, By Olaf P. Jenkins 83 



Salient Geologic Events in California and Their Relationship to Mineral Deposition, By Olaf P. Jenkins 89 

Position of the California Oil Fields as Related to Geologic Structure, By Ralph D. Reed 95 






GEOMORPHIC PROVINCES OF CALIFORNIA 

By Olaf P. Jenkins * 



OUTLINE OF REPORT 

Page 

Significance of the natural features 83 

Major pleomorphic provinces 83 

Great Valley of California 83 

Sierra Nevada 86 

Cascade Range 86 

Modoc Plateau 86 

Klamath Mountains 86 

Coast Ranges 86 

Transverse Ranges 87 

Peninsular Ranges (including the Los Angeles Basin) 87 

Colorado Desert 87 

Mojave Desert 88 

Basin-Ranges 88 



SIGNIFICANCE OF THE NATURAL FEATURES 

Even before the natural resources of this country 
: were developed, early explorers and settlers established 
the main avenues of travel and located most of the 
strategic points where great cities of the future were to 
be built. They knew the mountains and valleys better 
than do most of us today. To them a knowledge of the 
surface relief and, in fact, all physiographic features, 
i was vital. 

Since then, physiographic features have continued 
to be a constant guide to civilization. The supply, loca- 
tion, and accessibility of natural products have, to a 
large extent, controlled the development of industry. 

MAJOR GEOMORPHIC PROVINCES 

As we come to know more of the geologic history and 
structural evolution of the State (Reed and Hollister 36) 
we begin to realize how closely associated are its physio- 

\ graphic and geologic features. That a definite relation- 
ship exists between the major topographic features and 
the distribution of the rock formations, may readily be 
seen if the relief model of California is viewed side by 
side with the geologic map. 

Though extremely varied in detail, certain large 
areas of the State have many features in common. 

I These natural divisions are the physiographic or geologic 

; provinces (Reed, R.D. 33; Hulin, CD. 33). They have 
been outlined on Sheet III of the Geologic Map of Cali- 
fornia (Jenkins, O.P. 38) and also on the accompanying 
relief map. They have been designated geomorphic 

i provinces to indicate that the divisions have been made 
with due respect to the rock structure and its develop- 
ment throughout geologic history. These provinces, 
however, are well known and easily recognized. Their 
principal features, together with the position of the oil 
and gas deposits within them are outlined in the follow- 

[ ing paragraphs. 

Most of the oil and gas fields are found to be fairly 
well centralized in an area 230 miles long in a northwest- 
southeast direction, and 100 miles wide. All of the 

; known oil and gas deposits of the State occur in five of 

i the eleven provinces listed below. They are found (1) 
at the southern end of the Great Valley (also gas in the 

• Chief Geologist, California State Division of Mines. Manu- 
script submitted for publication July 22, 1940. 



central portion) ; (2) in the southwestern foothills of the 
Sierra Nevada; (3) at the southern end of the Coast 
Ranges; (4) at the western end of the Transverse 
Ranges; and (5) in the Los Angeles Basin, or north- 
western end of the Peninsular Ranges. 

LIST OF PROVINCES 
Great Valley of California 
Sierra Nevada 
Cascade Range 
Modoc Plateau 
Klamath Mountains 
Coast Ranges 
Transverse Ranges 

Peninsular Ranges (includes Los Angeles Basin) 
Colorado Desert 
Mojave Desert 
Basin-Ranges 

Provinces in which oil and gas fields occur are shown in bold- 
face type. Also the Colorado Desert contains a carbon-dioxide 
gas field. 

Great Valley of California 

The Great Valley of California is a central alluvial 
plain about 50 miles wide by 400 miles long, lying 
between the Coast Ranges and the Sierra Nevada, and 
containing a basin of interior drainage at its southern 
end. Locally, the northern part of the plain is called 
the Sacramento Valley, while the entire southern part 
is referred to as the San Joaquin Valley. The Sacra- 
mento and San Joaquin rivers, which join and enter 
San Francisco Bay, drain the great alluvial plain, with 
the exception of its southern extremity, though in time 
of high floods and with the aid of artificial canals, much 
of the water of this area may reach the master stream. 

The eastern border of the Great Valley joins the 
westward-sloping Sierra Nevada. The bedrock surface 
of this mountain range, in part covered by volcanic 
debris and in part by ancient stream gravels, continues 
westward beneath the alluvium and underlying Tertiary 
and Cretaceous sediments of the valley plain. 

The entire western border of this central plain is 
underlain by east-dipping Cretaceous and Cenozoie 
strata, which form a geosynclinal trough, lying beneath 
the Great Valley and closely skirting its western side. 

In the San Joaquin Valley, many prolific oil and gas 
fields are located on anticlinal uplifts which arch the 
immense thickness of sedimentary strata found deeply 
buried beneath the plain. Along its southern, south- 
western, and southeastern borders, extensive oil fields 
are located in the foothills which flank the surrounding 
mountains. On the west side of the valley the fields are 
on the edge of the Coast Ranges, while those on the east 
side north of Bakersfield, and on the southeast side, are 
in the foothills of the Sierra Nevada. All these prolific 
producing areas are usually listed in the one general 
district of the San Joaquin Valley. 

Commercial gas fields have recently been developed 
in the delta area where the northern end of the San 
Joaquin Valley merges into the southern end of the Sac- 
ramento Valley. 

To the north, where the monotonous plain of the 
Sacramento Valley is interrupted by the Marysville 



84 



Introduction to the Geology 



[Chap. IV 




Pig. 36. Relief map of California showing the geomorphic provinces as related to the topography. Photo of relief map (copyright) bv 

courtesy of H. A. Sedelmeyer, Berkeley, California. 



Geom orphic Province s — J enkins 



85 




ECONOMIC ^K' 
MINERALS 

FUELS jjj* \ 

IHM GAS DISTRICT 
mm OIL & GAS DISTRICT 

METALS 

♦ CHROMITE 
A COPPER 

<^5 GOLD DISTRICT 

IRON 

1 MANGANESE 

• QUICKSILVER 
8 SILVER 
T TUNGSTEN 

2 ZINC- LEAD 

NON-METALS 

A ANDALUSITE & KYANITE 

4: BARITE 

SANDSTONE 
Elf-BUILDING STONE- 
E3 

<• CLAY 

® DIATOMITE 

X GEMS 

& GYPSUM 

O IODINE 

© LIMESTONE, CEMENT, MARBLE 

O MAGNESITE 

IS MICA 

▼ PUMICE 

# SALINES 

• SOAPSTONE 
SULPHUR 

O TALC 

W WOLLASTONITE 



Fig. 37. Outline map of California showing the geomorphic provinces as related to the distribution of commercial mineral deposits. 



86 



Introduction to the Geology 



[Chap. IV 



Buttes, gas has been found in the upturned strata which 
flank this isolated and dissected dome of eruptive Ter- 
tiary rocks. 

Along the western border of the Sacramento Valley, 
only small amounts of oil have been found, and here it 
is in the rocks of Mesozoic age. 

Sierra Nevada 

The Sierra Nevada represents the dominant moun- 
tain range of California, a singular fault block of great 
magnitude, nearly 400 miles long, presenting a high 
multiple-scarp face on its east front, in contrast to the 
gentle western slope (about 2°), which disappears under 
the sediments of the Great Valley. Deep river-cut can- 
yons dissect its western slope. Their upper courses, 
especially in the massive granites of the higher Sierra, 
have been modified and rounded by glacial sculpturing. 

Near the eastern boundary of the province stands 
the continuously high crest -line of the Sierra, which cul- 
minates in Mount Whitney (elevation 14,496 ft., the 
highest point in the United States). Jagged canyons 
dissect the eastern scarp zone, formed by a series of 
great faults and dropped blocks. Along the base of the 
range, glacial moraines and alluvial fans spread out 
from the mouths of the canyons and conceal the more 
recent fault rifts, many of which may be of great magni- 
tude. 

The southern Sierra, characterized by massive 
granites, which have been raised higher and eroded to 
greater depth than the rocks of the northern end of the 
range, is terminated by the Garlock fault, which forms 
the northern border of the Mojave Desert. The southern 
tip of the Sierra Nevada ends at Tejon Pass, near the 
junction of the Garlock and San Andreas faults, where 
three other geomorphic provinces also join — the Coast 
Ranges, Transverse Ranges, and Mojave Desert. 

The north end of the Sierra Nevada terminates 
abruptly where the older rocks completely disappear 
beneath the Cenozoic volcanic cover of the Cascade 
Range and Modoc Plateau. In this part of the province, 
the older formations, composed of a metamorphic series 
of sediments and igneous rocks, form a huge northerly 
plunging anticlinal structure, the arching of which pre- 
dates the time of granitic intrusion. Gold-bearing veins, 
for the most part with north-south structural trend, 
have enriched the metamorphics along the western flank 
and northern end of the Sierra. 

The western foothills of the Sierra Nevada gradu- 
ally merge into the Great Valley. They are comprised 
of bed-rock, of Eocene sediments, of mud-flow materials, 
largely volcanic (Miocene and Pliocene in age), and of 
old alluvial gravels. To the south, these foothills are 
underlain by marine Cenozoic sediments and many 
important oil fields have been developed in them. 

Cascade Range 

The Cascade Range, which extends through Wash- 
ington and Oregon, also reaches into the northern cen- 
tral part of California. This province is represented by 
a chain of volcanic cones, dominated by the magnificent, 
glacier-mantled Mount Shasta, elevation 14,162 feet 
above sea level. Lassen Peak, the only active volcano in 
the United States, terminates the Cascade Range at its 
southern end. Pit River, after winding across the inte- 
rior Modoc Plateau en route to the Sacramento River, 



cuts a deep canyon transecting the range in the region 
between the two major volcanic cones, Shasta and 
Lassen. 

The foothills of the southwestern border of this 
province merge with the northeastern side of the Sacra- 
mento Valley, as in the case of the Sierra Nevada, and 
are comprised of volcanic mudflow beds, underlain by 
Eocene and Cretaceous sediments and overlain by old 
alluvial gravels. 

Modoc Plateau 

An interior platform (elevation 4,000 to 6,000 ft. 
above sea level) lies to the east of the Cascade Range, 
forming the southern extension of the immense volcanic 
plateau that covers eastern Oregon and southeastern 
Washington. It consists of a thick accumulation of lava 
flows and tuff beds and many small volcanic cones. 
Occasional lakes, marshes, and sluggish streams are 
found on its surface. Locally the province is known as 
the Modoc Plateau. It is bounded indefinitely on the 
east and south by the Basin-Ranges, and includes some 
of the characteristics of this eastern province as well as 
some of those of the Cascade Range. 

Klamath Mountains 

The topography of the Klamath Mountains is rugged 
and complex. Prominent peaks and ridges rise 6,000 to 
8,000 feet above sea level. The drainage is transverse 
and irregular, having developed on an uplifted plateau. 
Winding across the entire mountain mass through a deep 
and rugged canyon is the Klamath River. Successive 
benches with gold-bearing gravels occur on the sides of 
this and many of the tributary canyons. 

This province is more closely allied to the Sierra 
Nevada than to the Coast Ranges, and it continues into 
Oregon. Hard pre-Cretaceous rocks are exposed by 
deep stream dissection. Later volcanic rocks of the Cas- 
cade Range form the eastern boundary of the province, 
while Cretaceous sediments flank it on the southeast. 
Franciscan and younger Coast Range formations bound 
the province on its southwest side, where longitudinal 
faults and folds control the topographic features. 

Coast Ranges 

In a general sense the Coast Range system may 
include the coastal mountains throughout the entire 
length of California; but in a more restricted sense, the 
Coast Ranges are terminated on the north by the 
Klamath Mountains and on the south by the Transverse 
Ranges. For the sake of convenience, the province may 
be divided by San Francisco Bay into the Northern and 
Southern Coast Ranges. 

The Coast Ranges are characterized by longitudinal 
mountain ranges (2,000-4,000, and occasionally 6,000 
feet above sea level) and intervening valleys trending 
N.30°-40°W. Folding and faulting control the trend 
of the ranges. 

The province is terminated on the east where the 
strata dip beneath the alluvium of the Great Valley, and 
on the west by the shore of the Pacific Ocean. In many 
places, the coastal mountains rise sharply from the 
water's edge, and wave-cut, terraced flanks testify that 
they have recently been uplifted. 

The continuity of the coastal mountain trend is cut 
off obliquely by the coast line, especially to the north. 
Many submarine canyons and scarps transect the con- 



Geo m orphic Province s — J enkins 



87 



tinental shelf forming a rugged undersea topography. 
Some of these canyons have characteristics of surface 
erosion, others of fault scarps. The greatest of the sub- 
marine canyons is several thousand feet in depth and 
extends from Monterey Bay westward. On the other 
hand, opposite San Francisco Bay and the Golden Gate, 
through which the drainage of the Great Valley now 
reaches the sea, there is no submarine canyon, and the 
continental shelf is the widest to be found along the 
California coast. 

The northern Coast Ranges are dominated by irregu- 
lar knobby, landslide topography characteristically 
developed on the Franciscan Jurassic formation. It 
contains many fault valleys as yet unmapped. The 
eastern border is characterized by strike ridges and 
valleys developed in upper Knoxville Jurassic and Cre- 
taceous strata that border the western side of the Sac- 
ramento Valley. Volcanic cones and flows are promi- 
nent in the Northern Coast Ranges south of Clear Lake. 

The Southern Coast Ranges, including also the par- 
; tially submerged area about San Francisco Bay, are 
more diversified and complex. The topography is 
largely controlled by the geologic structure of Cenozoic, 
Cretaceous, and Franciscan sediments. The recently 
active San Andreas fault forms a dominating rift which 
trends slightly oblique to the adjacent ranges and 
i reaches from near Point Arena, in the Northern Coast 
Ranges, to the Gulf of California, a distance of more 
than 600 miles. A granitic core occurs in the Coast 
Ranges, extending from the southern extremity of the 
province, where it meets the southern tip of the Sierra 
Nevada, northwestward to Point Reyes Peninsula and 
the Farallon Islands. It is bordered on the east by the 
San Andreas fault, and on the west by a complicated 
system of earlier thrust faults and complex structures, 
sometimes referred to as the Nacimiento fault zone. 

Oil has been found in various places in the Coast 
Ranges and developed on a large commercial scale in 
the southern part of the province. Great oil fields 
follow anticlinal uplifts, which extend southeastward 
from the foothills of the southern Coast Ranges and 
disappear under the plains of the San Joaquin Valley; 
as for example, the Coalinga anticline which continues 
into the Kettleman Hills and southward to form Lost 
Hills. Likewise, farther south Belridge and McKittrick- 
Sunset follow uplifts along the foothills bordering the 
San Joaquin Valley. Along the coast, the Santa Maria 
Basin, a major oil district, lies in the southern extremity 
of the province. Development began in other minor 
fields of the Coast Ranges many years ago, but produc- 
tion from them has been small : Arroyo Grande, not far 
from San Luis Obispo; Sargent, south of San Jose; 
Moody Gulch and Half Moon Bay in the Santa Cruz 
'■ Mountains ; Mattole River Basin, Humboldt County, in 
• the northern end of the province. In the foothills which 
: border the western side of the Sacramento Valley minor 
amounts of oil and gas have been found in the upper 
Mesozoic strata. 

Transverse Ranges 

The Transverse Ranges consist of a complex series 
of mountain ranges and valleys distinguished by a 
dominant east-west trend in contrast to the northwest- 
southeast direction of the Coast and Peninsular Ranges. 



Subordinate trends, both northwest-southeast and north- 
east-southwest, are present, and are significant in the 
formation of important oil field structures. One of the 
thickest Cenozoic sedimentary sections occurs in the 
Transverse Ranges. The western limit of the province 
is found in the island group consisting of San Miguel, 
Santa Rosa, and Santa Cruz Islands. The eastern extent 
of the Transverse Ranges is within the Mojave Desert. 
The province includes the San Bernardino Mountains 
lying on the east side of the San Andreas fault, which in 
this region trends N.60°W., a change of 20° in its direc- 
tion (N.40°W.) found in the Coast Ranges. 

A large number of oil fields occur within the Trans- 
verse Ranges in the very thick series of Cenozoic sedi- 
ments deposited in the Ventura Basin. Along the coast, 
east and west of Santa Barbara and even beneath the 
water of the ocean are important fields; also in the 
mountainous region of the Ojai and Santa Clara Val- 
leys are numerous small and scattered fields. 

Peninsular Ranges (Including the Los Angeles Basin) 

The Peninsular Ranges, separated by long interven- 
ing valleys, conditioned by erosion along faults which 
are active branches of the San Andreas system, trend 
northwest-southeast. This trend is characteristic of the 
Coast Ranges, but the geology, excepting that of the Los 
Angeles Basin, is more like that of the Sierra Nevada. 
The dominating rocks are granitic, having invaded an 
older metamorphic series. The province is. continuous 
into Lower California. It is bounded on the east by 
the Colorado Desert through a series of right-angle jogs 
due to interruptions of fault traces. 

The Los Angeles Basin and the island group consist- 
ing of Santa Catalina, Santa Barbara, and the dis- 
tinctly terraced San Clemente and San Nicolas Islands, 
are included in this province. The submarine topogra- 
phy in this island region indicates the presence of 
numerous fault scarps and troughs. 

The Los Angeles Basin is one of the most important 
oil districts in California. It is an area of deep Ceno- 
zoic marine deposition and contains a large number of 
prolific producers within a limited and highly populated 
area of 25 by 35 miles. Some of the fields extend west- 
ward under the sea. A large part of the basin is covered 
by alluvium, though many good exposures of the oil- 
bearing sediments may be seen in road cuts. 

Colorado Desert 

Dominated by the Salton Sea, the Colorado Desert 
is a low-lying basin in part below sea level (minus 245 
ft.). The province is a depressed block between active 
branches of the alluvium-covered San Andreas fault 
zone. The southern extension of the Mojave Desert 
bounds the province on the east. Ancient beach lines 
and salt deposits of the extinct Lake Cahuilla charac- 
terize the topography near the boundaries of this 
province. 

Although no commercial oil or gas fuel deposits have 
been developed in the Colorado Desert, carbon-dioxide 
gas (from which dry ice is made) has been produced 
from wells of this province south of the Salton Sea. 
They lie directly above a branch of the San Andreas 
fault. The whole area is a structural trough and con- 
tains a basin of sediments surrounded and underlain by 
igneous and metamorphic rocks. 



88 



Introduction to the Geology 



[Chap. IV 



Mojave Desert 

The Mojave Desert, lying in the southeastern part 
of the State, includes a broad interior region of moun- 
tain ranges, separated by expanses of desert plains. 
Except for the immediate region of the Colorado River, 
bordering the province on the east, the drainage is 
inclosed and playas are numerous. The more prominent 
trend of the faults is northwest-southeast, while the sec- 
ondary trend is east-west, in apparent alignment with 
the Transverse Ranges, which seem to intercept the cen- 
tral part of the Mojave Desert and disappear into its 
alluvium-covered desert expanses. 

To the west, the province is wedged in a sharp angle 
between the Garlock fault (the southern boundary of 
the Sierra Nevada) and the San Andreas fault (here 
the eastern boundary of the Transverse Ranges) where 
it bends eastward from its major Coast Range trend. 
The Garlock fault separates the Mojave Desert on the 
north not only from the Sierra Nevada, but from the 
Inyo Mountains which represent a part of the Basin- 
Ranges province. The southern and eastern part of the 
Mojave Desert is often included in the Colorado Desert, 
but in this report the latter name is applied only to the 
structural trough about the Salton Sea. 



The greater part of the Mojave Desert is covered by 
alluvium, and extensive buried areas are thus concealed. 
The known geologic conditions of the province, how- 
ever, indicate that it is Underlain largely by metamor- 
phic and igneous rocks, with intervening areas covered 
by continental sediments, such as lake beds, mud flows, 
and alluvium. 

Basin- Ranges 

Lying wholly within the Great Basin drainage area, 
and distinctly characteristic of Nevada, the physi- 
ographic province known as the Basin-Ranges occurs in 
California, east of the Sierra Nevada and Modoc 
Plateau, and north of the Garlock fault. It is a region 
of interior drainage with lakes and playas. Roughly 
parallel ranges alternating with basins and troughs are 
controlled by typical fault block structure; Death Val- 
ley (280 feet below sea level) is one of these troughs or 
grabens; another is Owens Valley, lying between the 
Inyo Mountains and the bold eastern fault scarp of the 
Sierra Nevada. 

Igneous and metamorphic rocks comprise most of the 
mountains of this area, though intervening valleys are 
covered with alluvium, lake beds, and other continental 
sediments. 




Fio. 38. Map of California showing intensity of average precipitation. Repub- 
lished from Sheet IV, Geologic Map of California, 19S8. 



SALIENT GEOLOGIC EVENTS IN CALIFORNIA AND THEIR 
RELATIONSHIP TO MINERAL DEPOSITION 

By Olap P. JenkiitS * 



OUTLINE OF REPORT 

Page 

Significance 89 

Pre-Cambrian : the oldest rocks 91 

Paleozoic 91 

Mesozoic 91 

Tertiary 92 

Pleistocene 92 

Recent 93 



SIGNIFICANCE 

The manifold variety of physical features of Cali- 
fornia is well matched by a most varied and eventful 
geologic record. This record, well chronicled from the 
earliest known rocks through every major period in the 
earth's time scale down to the very active present, 



• Chief Geologist, California State Division of Mines, 
script submitted for publication July 22, 1940. 



Manu- 



places California in an especially favored position for 
the study of historical geology. 

The salient events in this long geologic record appear 
to be closely connected with the processes responsible 
for the physical features, and also for the origin and 
accumulation of the State's mineral deposits. From 
these deposits, during the past 92 years, 9\ billion dol- 
lars worth of mineral products have been extracted. 
Nearly 60% of this mineral wealth came from the oil 
and gas industry alone. Though this industry is the 
largest and most progressive in the State, it has made 
its phenomenal growth only during the last 30 years. 

Exploration and discovery of the oil and gas fields 
of the State have largely been in the hands of geologists, 
who have made an intensive study of the geological for- 
mations and history of the rocks most closely associated 
with oil and gas. These formations are for the most 



[mjtco •• (*rorn V in i 



NATURAL GAS 



COMMERCIAL MINERALS OF CALIFORNIA 



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Fio. 39. Chart giving list of commercial minerals produced in California, and 
showing how each county has contributed to this production. Prepared by the California 
State Division of Mines. 



CALIFORNIA MINERALS 




TOTAL VALUE (J846-I938) 
9 '/« BILLION DOLLARS 



Fig. 40. Graph showing comparative 
total values on groups of commercial 
minerals produced in California, 1848- 
1938. 



90 



Introduction to the Geology 



[Chap. IV 





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Salient Events in the Geologic Histor y — J enkins 



91 



part the marine sediments of the middle and upper 
Cenozoic. Recently, however, gas in commercial quan- 
tities has been produced from the Cretaceous as well as 
from lower Tertiary strata, leading geologists to focus 
more attention on these older beds. 

Pre-Cretaceous rocks, though they represent only 
the "basement" in the oil fields of California are of 
enormous thickness and wide areal extent. Most of the 
gold deposits and many of the other commercial min- 
erals are associated with the pre-Cretaceous rocks, espe- 
cially with those of the Jurassic. Tertiary mineraliza- 
tion, however, is also important; it is associated with 
igneous activity of that age. 

The accompanying diagram, which also appears on 
the margin of Sheet V of the Geologic Map of Califor- 
nia (Jenkins, 0. P. 38), was drawn to give an idea of 
"looking back in geologic time." Some of the most 
"salient geologic events in California" are listed on this 
chart. By examining it, together with the State map, 
one may realize the importance of that limited part of 
the historic record which concerns particularly the oil 
and gas industry. 

PRE-CAMBRIAN: THE OLDEST ROCKS 

To assign rocks definitely to the pre-Cambrian (esti- 
mated to be over 500 million years old), it is necessary 
i to have Lower Cambrian beds, present and in proper 
structural relationship to the older formations lying 
beneath them. This situation is found in the desert 
mountains of San Bernardino and Inyo counties, where 
there are two great series of pre-Cambrian rocks — the 
older a highly metamorphosed group, the younger a 
series of marine sediments, in part algal limestones with 
1 intruded basic igneous sills. 

The oldest important mountain-making event in the 
geologic history of the State may be found recorded by 
pre-Cambrian igneous intrusions and by the accom- 
panying regional metamorphism. This event seems to 
have had pre-Cambrian mineralization associated 
with it. 

Ancient schists occurring in other parts of the State 
may in some cases also be pre-Cambrian in age. These 
would be the highly and regionally metamorphosed 
rocks; for local well-formed schists of much younger 
age are frequently found in the Jurassic, and most of 
the pre-Jurassic rocks are at least in part meta- 
morphosed. 

PALEOZOIC 

Practically the entire Paleozoic column is found in 
Inyo and San Bernardino counties. The lower part of 
the section, including the Cambrian and Ordovician, is 
known definitely to occur in this southeastern desert 
region of California. In the northern Sierra Nevada 
and Klamath Mountains, rocks known to be of Silurian, 

! Devonian, Carboniferous, and Permian age have been 
described and mapped ; but there has never been dis- 
covered any clue as to the geologic period to which the 
still older rocks of the Klamath region belong. Many 

; of the so-called "pre-Devonian" rocks of the Klamath 
Mountains may extend down into the pre-Cambrian. 
The ancient schists, which are quite extensive in this 
region, appear to be very old ; indeed, it is quite likely 
that many of them represent the pre-Cambrian. 



Outstanding events, such as mountain-building, 
appear to be lacking in the history of the Paleozoic of 
California; and there seems to be no great period of 
mineralization for that era. Broad seas stretched across 
areas now covered by the northern mountains, and the 
resulting marine deposition spread limestones, shales, 
and other sediments over very large areas. A change in 
this monotonous condition may have come in the latter 
part of the Paleozoic, recorded by some indications of 
volcanic activity. 

One may wonder if the extensive marine sediments 
of the California Paleozoic might not have once con- 
tained oil and gas, as they now do in the middle-western 
States. If so, such deposits have long been obliterated, 
undoubtedly as a result of the severe treatment received 
during the geologic events that followed 'the Paleozoic 
era in California. 

MESOZOIC 

As a time of great events, no part of the geologic 
record of California is so impressive as the middle of 
the Mesozoic. Clearly, it was a period of mountain- 
building and igneous intrusion which affected the older 
rocks throughout practically the entire State. As a 
result, the rocks older than this so-called "Nevadan" 
orogenic period of the Jurassic are of entirely different 
character and structure than any of the rocks which 
were formed after this series of harsh episodes. 

Volcanic activity, definitely recorded in the Triassic, 
probably initiated the great orogenic epoch which fol- 
lowed. Widespread seas fringed with coral reefs still 
existed during the early Mesozoic, as an inheritance from 
the late Paleozoic. 

Thus limestones and dolomites, so prominent in the 
Paleozoic and Triassic, gave place to the Jurassic detrital 
sediments, the result of extensive erosion. During this 
period, the sediments were folded, metamorphosed, and 
intruded by igneous rocks both basic and granitic. Vol- 
canic action was prominent, for the sediments of the 
Jurassic contain much intercalated extruded material, 
such as breccias, pillow basalts, etc. All this activity was 
so widespread that it extended from one end of the State 
to the other. With the basic intrusions of the Sierra 
Nevada and Klamath Mountains, copper was deposited. 
Gold-bearing quartz veins, as the end products of 
granitic intrusive action in these same regions, were 
formed during the latter part of the Jurassic and the 
early Cretaceous. 

In the Coast Ranges, ultra-basic rocks — serpentines 
and the like — were intruded into the Upper Jurassic 
sediments. These rocks are found to contain chromite 
as magmatic segregations, and magnesite as a later 
leached product of serpentine. Red radiolarian cherts 
interbedded as lenses within the sandstones and shales, 
are prominent, and in places contain manganese bodies 
deposited contemporaneously with the sediments. That 
some oil was formed within these Jurassic marine sedi- 
ments of the Coast Ranges, and then largely destroyed 
is indicated by a few very small seepages in the Fran- 
ciscan and Knoxville formations of northern California. 
In places, they are associated with mineral springs and 
quicksilver deposits, usually in fault zones, fractured 
during late Cenozoic time. The Franciscan Jurassic 
formation of the coast, together with its intruded ser- 



92 



Introduction to the Geology 



[Chap. IV 



pentine is so badly fractured and contorted nearly every- 
where, that the broken material near its present surface 
is prone to move readily as landslides. 

That an outstanding period of erosion should follow 
the most important orogenic epoch of the State's history 
would be expected. A complete change in the distribu- 
tion of the land and water, so that mountains were left 
standing where once was a broad expanse of sea, cer- 
tainly presented a topographic condition which favored 
widespread erosion of newly formed land, together with 
deposition of clastic sediments in the sea. The shore- 
line of this period — the Cretaceous — lay west of the 
present Sierra Nevada, for the earlier broad inland sea 
that stretched across the region was wiped out of exist- 
ence by the rising mountains. Several miles of strati- 
graphic thickness of conglomerates, sandstones, and 
shales, deposited in the Cretaceous sea, now give testi- 
mony of this period of widespread erosion. The sedi- 
ments may be found throughout the coastal part of the 
State from Oregon to the Mexican border. 

TERTIARY 

Some uplifting in the Coast Ranges continued from 
the Cretaceous into the early Eocene, but it is hardly 
regarded as a prominent orogenic period. Evidence of 
Laramide orogeny, the great mountain-building period 
of the Cordillera farther east, has been recognized in 
the southeastern part of the State. 

The lowest part of the Eocene, or Paleocene, 1 is so 
intimately associated with Upper Cretaceous that it is 
only with difficulty that the two series of rocks may be 
separated. 

Of all the rock series of the Tertiary, those of the 
Eocene have the widest, most continuous distribution. 
Together with the Cretaceous, the Eocene extends from 
the Oregon boundary to Mexico. Certain features of 
the Eocene show that its environment was singularly 
different from the periods preceding or antedating it. 
Fossil and other evidence show it to have had a tropical 
or semi-tropical climate. This feature, together with 
the fact that it was a time of no appreciable uplift, gave 
rise to deep secular decay and advanced weathering, 
which resulted in: (1) the formation of high-grade clays, 
both along the base of the western slope of Sierra 
Nevada and in the northwestern part of the Peninsular 
Ranges; (2) the formation of low grade coals associated 
with the clays; (3) the deposition of quartz sands in 
the foothills bordering the San Joaquin Valley; and 
(4) the releasing of gold from bed-rock formations, per- 
mitting it to be washed into stream channels, some of 
which became buried beneath volcanic blankets that cov- 
ered the Sierra Nevada during Miocene and Pliocene 
time. 

Recently discovered prolific oil fields in the marine 
Eocene sediments, and important commercial gas fields 
in both the Eocene and its close associate, the Cretaceous 
in northern California, have added immense potential 
wealth to the rocks of these periods. 

Undoubtedly the ancient archipelago, which charac- 
ized the physical aspect of the Coast Range region dur- 
ing the Tertiary, began in the Upper Cretaceous, gradu- 

1 A name now generally adopted. 



ally developed during the Eocene, was highly advanced 
in the Miocene and Pliocene, then disappeared in the 
Pleistocene. The remnant of this physiographic condi- 
tion is now found only in the Channel Islands. 

Deep troughs, more or less land-locked, which lay 
between the islands and land masses, may have been 
responsible for the accumulation of organic materials to 
form the prolific oil and gas fields of southern California. 

The diatomaceous and foraminiferal shales so promi- 
nent in the formations of the later Tertiary, began to 
appear prominently in the Upper Cretaceous. All 
periods of the Tertiary have these organic shale repre- 
sentatives. 

Tertiary volcanic activity in the late Eocene and 
Oligocene caused the first thin layers of rhyolite ash to 
be distributed as local lake beds over the ancient gold- 
bearing stream channels of the Sierra Nevada. A much 
more violent volcanic activity, widespread and promi- 
nent throughout the State in the Miocene and Pliocene, 
continued into the Pleistocene ; and, though it has waned 
considerably, it has not entirely stopped, even today. 

Lava flows completely covered to great depth the 
northeast part of the State. Mudflows, now partly 
removed by erosion, blanketed the northern Sierra 
Nevada. Basalts and rhyolites, together with submarine 
expulsions of volcanic material, characterize many of 
the Tertiary rocks of the Coast Ranges. The thick dia- 
tomaceous accumulations in the Tertiary have been 
attributed to a siliceous condition of the sea water, 
caused by the volcanic activity. Mineral deposits of 
the southeastern part of the State were associated with 
vuleanism of the Tertiary. 

As this volcanic activity waned in the Coast Ranges, 
mineral and hot springs continued along the fracture 
planes which extend far down into the hot magmatic 
portion of the earth 's rocks. These deep fracture zones, 
developed in the late Jurassic through faulting, crush- 
ing, and the expansion of basic igneous rocks during 
their alteration into serpentine, were re-fractured and 
faulted during the later geologic periods. The fracture 
zones thus formed have supplied avenues by which 
mineralizing solutions containing quicksilver were 
brought near to the surface. California's quicksilver 
mining districts constitute one of the world's chief 
sources of this liquid metal. 

PLEISTOCENE 

Though much folding was going on during the Mio- 
cene as well as throughout the entire Cenozoie, these 
slower movements became more especially active in 
the Pliocene. The Pleistocene, however, is especially 
marked as a period of State-wide faulting, not only in 
the coastal regions, as along the San Andreas and Gar- 
lock fault rifts, but in the Basin Ranges. The great 
displacements along the eastern front of the Sierra 
Nevada are particularly impressive. 

It is not unreasonable to attribute a large part of the 
migration of oil into anticlines to the folding of the Plio- 
cene. On the other hand, leakage from some of these 
accumulations along faults certainly took place in the 
Pleistocene and Recent, as evidenced by many large 
brea pits. 



Salient Events in the Geologic Histor y — J enkins 



93 



A period of orogeny is attributed to the Pleistocene, 
and variously called by such names as "Santa Bar- 
baran" or "Pasadenan. " Volcanic activity still con- 
tinued in some regions as in Modoc and Lake counties. 
The Sierra Nevada was re-elevated to a great height, and 
deep canyons were cut in these westward-tilted moun- 
tains. Glaciers were prominent in the high mountain 
valleys. Deep canyons were also cut in the uplifted and 
emerged continental shelf, which now rests far beneath 
the ocean 's surface. Stream dissection of geologic struc- 
tures in the Coast Ranges, and the uncovering of vol- 
canic blankets in the Sierras, characterize the work of 
the Pleistocene. This led to the formation of thick 
gravel deposits both on land and in the sea. Probably 
the thickest Pleistocene marine deposits in the world 
occur in Ventura County, and their tilted and faulted 
condition shows much activity since that time. 



RECENT 

The climate of the Pleistocene was cold. Inland 
lakes of broad extent were a common feature of the land- 
scape. As these lakes disappeared and the mountain 
glaciers retreated, a more arid climate developed as of 
today. Volcanic activity quieted down; but occasional 
earthquakes indicate that faults are still active. 

The physiographic features as we see them now are 
an evolutionary outgrowth of an older varied and event- 
ful history, recorded faithfully for more than half a 
billion years. But the periods closer to us in time have 
affected the surface features the most. Thus, as we look 
back in geologic time, the actual record disappears in 
the distance as the vanishing point in perspective, while 
the features which appear the largest and most impor- 
tant to us, are often the result of things that have hap- 
pened nearest to us in geologic time. 




Fig. 42. Chart, drawn on logarithmic scale, to show relative importance of various commercial minerals produced in California. 

Reprinted from Economic Mineral Map of California No. 1 Quicksilver. 



Introduction to the Geology 




Fiq. 43. Map showing size and dlmensons of California and its 58 counties. Republished from Sheet V, Geologic Map of California, 193S. 



POSITION OF THE CALIFORNIA OIL FIELDS AS RELATED TO GEOLOGIC STRUCTURE 



By Ralph D. Reed * 



OUTLINE OF REPORT 

Page 

Regional structure 95 

Local structure 97 



REGIONAL STRUCTURE 

Important oil resources are found only in a small 
part of California; specifically in a part of the coastal 
mountain-and-valley province. We tend to think of oil 
as a Coast Range product, but we have to recognize that 
thus far we have failed to find it in paying quantities 
anywhere in the Northern Coast Ranges or in approxi- 
mately half of the Southern Coast Ranges. If we recog- 
nize the Transverse Ranges as a region separate from the 
Coast Ranges proper, we may almost say that oil is a 
product of the Transverse Ranges and some of the inter- 
vening and adjacent valleys, and that much the greater 
part of the Coast Ranges is entirely barren of producing 
wells at present. 

The oil-producing region has been classified struc- 
turally in several different ways, and other classifications 
are no doubt possible. The Reed and Ilollister classifi- 
cation (Reed, R. D. 36, p. 14, ff.) makes use of provinces 
distinguished by the evolutionary course through which 
they have passed. Provinces underlain by granitic 
basement and characterized by a notably discontinuous 
blanket of Cretaceous and Tertiary strata are given 
names ending in "ia", and are three in number. They 
are called Mohavia, Salinia, and Anacapia. Provinces 
with a Franciscan basement, if they were strongly nega- 
tive during the later Mesozoic but acted in a dominantly 
positive manner during the Tertiary, are called "up- 
lifts", and are also three in number: the Diablo, San 
Rafael, and Catalina uplifts. Provinces underlain at 
least in large part by Franciscan rocks but strongly 
negative throughout the Tertiary are called embay- 
ments — San Joaquin, Santa Barbara, and Capistrano 
embayments. The landward end of each of these embay- 
ments is a place of particularly rapid subsidence dur- 
ing the Tertiary, and is called a basin. Like the embay- 
ments, they are three in number — the Maricopa, Ven- 
tura, and Los Angeles basins. One other uplift, the 
Oakridge uplift, is recognized. It subsided strongly 
during the Paleogene 1 but was emergent during most of 
the Neogene. 2 It may be thought of as a Neogene devel- 
opment from a part of the Santa Barbara embayment. 
1 There is also a fourth important basin, that of Santa 
Maria, which, like the Oakridge uplift, developed after 
the Paleogene. Before that it was a part of the San 
Rafael uplift. 

Figure 45 shows the provinces just defined, and the 
location of the more important oil fields of California. 
A study of this map shows some interesting relation- 
ships that may be important: (1) Salinia and Anacapia 
have no oil fields, though the former has many seepages 
and has been widely recognized as a promising area for 
; prospecting. (2) Mohavia has no oil fields, though the 
Bakersfield district might be thought of as belonging 

•Chief Geologist, The Texas Company of California. Manu- 
script submitted for publication May, 1939. Dr. Reed died January 
;29, 1940. 

*See pp. 117-118. 
'See pp. 112-116. 



rather to the western, buried edge of that province than 
to the San Joaquin embayment. (3) The Diablo uplift 
has no oil fields. (4) The Catalina uplift has several 
oil fields near its boundary with the Los Angeles Basin, 
west of the Newport-Inglewood belt. This producing 
area, which has furnished the Torrance, Playa del Rey, 
and several more recent fields, is often considered a part 
of the Los Angeles Basin but belongs, in its structural 
aspect, to the Catalina uplift. (5) The San Rafael 
uplift has the oil fields of the Santa Maria district in 
the area that became a basin after the Paleogene. (6) 
The Oakridge uplift has several oil fields, most of them 
near its boundary with the Ventura Basin, but a few 
(Simi and Tapo Canyon fields) much farther away. 
(7) The greater number of the more important fields 
and many of the less important ones lie in the San Joa- 
quin, Santa Barbara, and Capistrano embayments, and 
show a distinct tendency to be concentrated in the land- 
ward ends, deepest parts or basins, of these embayments. 




Upper 
Cretaceous 

(Chi co) 



Lower 
Cretaceous 

(Ghasfa) 
CKnoxville") 



Franciscan 



Regional Unconformity. 



Oil in San Joaquin Valley, 
Los Angeles 5asin and 
Ventura County. 

Local unconformity. 
Oil in Kettleman Hi lis. 
Great Transgression. 
Local Unconformity. 
Oil in Elwood and Capitan. 

Much Land- laid Material. 
Oil in Yenhjra 4 Santa Barbara Co 

Oil in Belndge $ Ventura Co. 
Great Transgression. 



Regional Unconformity. 

Small oil production in 
Coalinga District 



Regional Unconformity 
3ooo' TO 9000' 



Fio. 44. Generalized stratlgraphic column of the Coast Ranges 
showing positions of major oil zones. 



96 



Introduction to the Geology 



[Chap. IV 




Position of the California Oil Field s — R eed 



97 



It is perhaps worth noting as an interesting coin- 
cidence that Tertiary volcanic rocks tend to be concen- 
trated just in those types of province that have the 
smallest number of important oil fields. 

LOCAL STRUCTURE 

The local structure of oil accumulations will be per- 
ceived more readily by perusal of the pages that follow 
this introduction than by any amount of general dis- 
cussion. All that can be attempted here is a classifica- 
tion of the more important types of structural trap that 
have yielded oil in California and a brief discussion of 
a few of the more important structural problems that 
have not yet been satisfactorily solved for some fields. 

It will be noticed that a good many of the older fields 
are classified or.ly provisionally, or not at all. The 
reason for this procedure is chiefly a lack of data. It 
should be recalled that records are not available for 
many of the older wells, and that records showing the 
data now considered necessary to keep are not available 
for any of them. For most fields, oil field stratigraphy 
scarcely existed before 1920. Well logs showed, in gen- 
eral, no markers that could be recognized from well to 
well, except oil sands. Very little was known even about 
the sands, and substantially nothing about the shales. 
Something could be learned under favorable circum- 



stances, but most of the problems about subsurface 
stratigraphy and structure in which oil geologists are 
now , interested were in the earlier years only matters 
for surmise. 

During the last fifteen years there has been a great 
change. The introduction of coring, of micropale- 
ontology, and of the Schlumberger logging method have 
led to a detailed study of many subsurface phenomena 
about which geologists were formerly very much in the 
dark. The recognition of thin microfaunal zones or of 
numerous Schlumberger "markers" permits us to form 
opinions about the occurrence of oil in the formations, 
about the presence or absence of faults, and about the 
details of folding. We are thus better informed about 
subsurface conditions in the North Dome of Kettleman 
Hills than we are likely ever to be in the old Coalinga 
Eastside field. Unconformities in the more recent fields 
are known, in the older fields they must be largely 
inferred from very sketchy evidence. 

With these facts in mind, we may find it useful to 
examine the following list, in which oil fields are classi- 
fied according to what seems to be the dominant type of 
structural control. Many of the older and less impor- 
tant fields are omitted, as are some recent fields in which 
development has not yet gone far enough to furnish a 
very trustworthy basis for an opinion. 



TABLE 



TYPES OF OIL ACCUMULATION IN CALIFORNIA, 
WITH EXAMPLES. 


A. Accumulations In normal closed anti- 
clines; faulting minor or not of such 
type as greatly to affect accumulations; 
unconformities supposed to be absent or 
of slight importance. 


1. North Dome of Kettleman Hills 

2. Kiddle Dome of Kettleman Hills 

3. North Belridge (middle and lower Miocene oil) 
A. Ten Sections (faulting possibly influential) 

5. Rio Bravo (faulting possibly influential) 

6. Wheeler Ridge 

7. Elwood (marginal faulting important?) 

8. Ventura Avenue 

9. Dominguez (Pliocene oil) 

10. Santa Fe Springs 

11. Meat Coyote 

12. Seal Beach 


B. Accumulations in anticlines, with 
faulting an important secondary 
control. 


1. South Mountain (data not very conclusive) 

2. Inglewood 

3. Dominguez (Miocene cil) 

4. Long Beach 

5. Santa Maria or Orcutt 
f>. McXittrick 

7. Huntington Beich 

8. Wilmington 

9. Richfield 


C. Accumulations in anticlines, with 

overlap or unconformity as essential 
secondary control. 


1. Elk Hills (particularly eastern development 

2. Buena Vista Hills (particularly northwestern area) 

3. North Belridge (Pliocene oil) 

4. Belridge (Pliocene oil) 

5. Playa del Rey 


D. Accumulations in sand lens on plunging 
anticline, possibly without effective 
unconformity. 


1. Coalinga Eastside (Eocene oil) 


E. Accumulations due to unconformity, type 
of fold incidental or secondary. 


1. Coalinga Weatside 

2. Midway-Sunset fields 

3. Santa Maria Valley 

4. Edison 


?. Fault accumulations. 


1. Mt. Poao 

2. Round Mountain 

3. Mountain View 

4. whittler 

5. brea-Olinda 



Chapter V 

Geologic History and Structure 



CONTENTS OF CHAPTER V 



California's Record in the Geologic History of the World, By Ralph D. Reed. 



Geologic History and Structure of the Central Coast Ranges of California, by N. L. Taliaferro. 



Paq« 

. 99 
. 119 



CALIFORNIA'S RECORD IN THE GEOLOGIC HISTORY OF THE WORLD 

By Ralph D. Reed * 



OUTLINE OF REPORT 

Page 

Pre-Cretaceous 99 

General discussion 99 

Devonian 101 

Permo-Carboniferous 101 

Triassic 102 

Jurassic 104 

Cretaceous 108 

Lower Cretaceous 10S 

Upper Cretaceous 109 

Tertiary 112 

General statement 112 

Base of the Tertiary 112 

Lower Paleogene 112 

Upper Paleogene 115 

Transition, Paleogene to Neogene 117 

Lower Neogene 117 

Upper Neogene 117 

Close of Upper Neogene and post-Tertiary record UN 



PRE-CRETACEOUS 
General Discussion 

Inasmuch as the pre-Cretaceous formations of the 
Coast Ranges carry no more than traces of oil and gas, 
they may be grouped together in a discussion of oil 
deposits and called "basement." Ordinarily this base- 
ment is divided into a "granitic" and a Franciscan 
series— structurally important divisions that are fairly 
easy to distinguish. The pre-Cretaceous stratigraphic 
units that, are commonly used elsewhere are, in fact, 
recognizable only very locally among the older rocks of 
the coastal mountains of California; and it is only in 
eastern California, particularly in the eastern Mojave 
Desert, that these strata are sufficiently unmetamorphosed 
to have furnished thick and well-classified sections of the 
Paleozoic and pre-Paleozoic (Hazzard, J.C. 37, pp. 289- 
339). The Paleozoic strata are sufficiently fossiliferous 
to be divided into several formations, referable to the 
various systems that are found in other parts of the 
world. All of the Grand Canyon formations of both 
Paleozoic and pre-Paleozoic are found in eastern Cali- 
fornia with little change except an increase in thickness ; 
and between some of them are new formations not repre- 
sented at all in the Grand Canyon section. 

Just what happens to these older formations farther 
west toward the Coast Ranges is not clear. Limestone 
and schist of possible or probable Paleozoic age occur 
in many places, as in the San Bernardino, Santa Lucia, 
Gabilan, and Santa Cruz Mountains, but the absence of 
identifiable fossils makes their age uncertain. They may 
all be Carboniferous; they may represent the whole 
Paleozoic; they may include both Paleozoic and pre- 
Paleozoic ; or they may be entirely pre-Paleozoic. In 
view of the uncertainty, the casual way in which some 
writers deal with the question of a Paleozoic "Cascadia" 
to the west of the marine deposits of known Paleozoic 
age in California and Nevada is likely to rouse either 
considerable admiration or doubt. If Cascadia existed, 
where are the clastic deposits that accumulated near its 
borders ? 



The problem of the southward extension of the for- 
mations of the Cordilleran geosyncline is not much 
simpler and is almost equally important. The southern- 
most section of known Paleozoic rocks is that of the 
San Bernardino Mountains, discussed by Vaughan 
(Vaughan, F.E. 22), and also bv Woodford and Harriss 
(Woodford, A.O. 28, p. 270). The fossiliferous forma- 
tion, designated Purnaee limestone by Vaughan, is about 
4,500 ft. thick and consists of limestone with schistose 
and graphitic horizons; it lies upon the Arrastre quartz- 
ite, mostly thin-bedded and more than 2,500 ft. thick; 
and is overlain by the Saragossa quartzite, 3,500 or more 
feet thick, with pebbly and cross-bedded layers. The 
few fossils found in the Furnace limestone are con- 
sidered to be Carboniferous in age ; the quartzites are 
presumably Paleozoic ; but the older members might be 
of any age from Ordovician — perhaps even from Cam- 
brian — to Carboniferous, the younger may be Carbon- 
iferous or Permian. Most interest attaches to the 
quartzites from the exceptional degree of coarseness 
which they impart to the 10,000-ft. series of Paleozoic 
strata comprising the San Bernardino Mountain section, 



• Chief Geologist, The Texas Company of California. Manu- 
script submitted for publication May 1939. Read before the Sixth 
Pacific Science Congress at Berkeley, California, July-August, 1939. 
Dr. Reed died January 29, 1940. 



NOPAH- RESTING SPRINGS 

(CALIFORNIA) 



GRAND CANYON 

(ARIZONA) 



EUREKA QTZ 




Fig. 46. Comparative columnar sections nl tin Paleozoic in 

California and Arizona 



100 



Geologic History and Structure 



[Chap. V 



Table 1 



PALEOZOIC FORMATIONS OF HOP AH AMD RESTING SPRING MOUNTAINS, 
AFTER J.C. HAZZARD. 

Bote that fossils are absent b«low the middle of the Wood Canyon formation. Thus, 
several thousand feet of strata are referred to Lower Cambrian because they lie 
above the "marked unconformity" at the base of the Noonday dolomite; an unconform- 
ity that looks like a good lower limit to the Paleozoic rocks but is not otherwise 
closely dated. 


CARBONIFEROUS 
Upper 

Lower 


3,000 ft. 


Bird Springs formation, 780+ ft., mostly limestone; 
fossils near top 

Monte Cristo limestone, 987+ ft., massive, crinoidal; 
fossils 300-350 ft. above base 


Possible unconformity 


DEVONIAN (Kiddle) 


900 ft. 


Sultan dolomite, 890 ft., fossils 


Unconformity 


SILURIAN (or ORDOVICIAN) 


335 ft. 


Unfossiliferous dolomite 


ORDOVICIAN 
Upper 
Middle 
Lower 


2,100 ft. 


Ely Springs (?) dolomite, 800 ft., fossils in lower part 

Eureka quartzite, 265 ft., fine-grained, no fossils 

Pogonip (?) limestone, 1,040 ft., largely dolomitic, 
fossils near top 


CAMBRIAN 
Upper 

Middle 
Lower 


16,598 ft. 


Nopah formation, 1,7^0 ft., dolomitic limestone with 
100-ft. shaly zone at base 

Cornfield Springs formation, 2,975 ft., chiefly lime- 
stone, thin fossil-bearing shaly limestone at base 
Bonanza King formation, 1,515 ft., mostly limestone 
Cadiz formation, 692 ft., limestone and shale, fossils 
near top 

Wood Canyon formation, 3,033 ft., quartzite, shale, and 

limestone, fossils in upper half 

Stirling quartzite, 2,593 ft., no fossils 

Johnnie (?) formation, 2,550 ft., shale, etc., no fossils 

Noonday dolomite, 1,550 ft., no fossils 


Marked unconformity 


PRE-CAMBRIAN 




Varied rocks of unknown thickness 






California's Recor d — R eed 



101 



more than 6,000 ft. of which is quartzite. It is hard to 
point to any other Paleozoic section of the State that is 
equally coarse. Is the coarseness due to deposition near 
an upland which lay, in general, either too far west or 
too far south to furnish similarly large amounts of 
clastic material to the Paleozoic formations of the Inyo 
Mountains, the Death Valley region, or the area near 
Cadiz? 

A further inteiesting fact about the Paleozoic is that 
no fossiliferous formations of this age have thus far 
been found in the Transverse Ranges east of the San 
Bernardino Mountains or anywhere to the south of them 
in California. 1 The whole area is in need of detailed 
mapping and much of it even of reconnaissance study; 
but enough has been examined so that the total absence 
of Paleozoic fossils begins to be suggestive. It suggests 
the possibility of a western extension of Mazatzal land 
which, according to Professor Stoyanow (Stoyanow, 
JA.A. 36), separated the Paleozoic sea of northwestern 
Arizona from that of southeastern Arizona. Both faunal 
and lithological considerations, he says, bear out this 
interpretation. Since Mazatzal land is a direct eastward 
continuation of the Transverse Ranges province of 
southern California, the facts suggest that perhaps this 



1 A Mlssissippian coral has now been found somewhat south 
of the Transverse Ranges. See Webb, R.W. 39. Note supplied the 
editor by A. O. Woodford, September 19, 19i0. 




APPROXI MATE LOCAT ION 

OF 

CORDILLERAN GEOSYNCLINE 

DURING THE PALEOZOIC 



^io. 47. Map showing some of the possible geographic conditions 
of the Paleozoic. 



area marked the southern terminus of the Cordilleran 
geosyncline. This possibility is further supported by 
the fact that the Transverse Ranges mark the southern 
terminus, so far as now known, of the great belt of 
eastward-thrust faults which extends from the Canadian 
Rockies through western Montana and Wyoming, the 
Wasatch Mountains, the Muddy Mountains and Good- 
springs region, at least to the Shadow Mountains of 
eastern California. If the belt of thrusting, which for 
many hundreds of miles follows the eastern edge of the 
geosyncline, terminates north of the Transverse Ranges, 
it seems likely that the geosynclinal belt either terminates 
there too, or else that it takes a sharp bend to the west 
and passes into an area where its presence has never 
been proved. 

Enough has been written, perhaps, to demonstrate 
again the fact that much more work needs to be done on 
the Paleozoic rocks of western and southern California. 
It is also a fact, however, that much additional work is 
needed on the known Paleozoic sections in eastern Cali- 
fornia and Nevada. As is well known, the western part 
of this belt was strongly affected by the Nevadian 2 
(Upper Jurassic) period of folding, the eastern part by 
the Laramide (Upper Cretaceous to Tertiary) period. 
Nolan has summarized (Nolan, T.B. 28) the evidence 
tending to show that in later Paleozoic time the Cor- 
dilleran geosyncline was divided into two parts by a 
north-south central area of relatively slow subsidence, 
and Stille has synthesized (Stille, H. 36) the data that 
suggest a different age for the folding of these two parts 
and for the varying igneous histories of the two. 

Since Lower Paleozoic rocks are entirely unknown 
in the Coast Ranges and nearly so in the Sierra Nevada, 
they will not be further discussed here. The Upper 
Paleozoic — Devonian, Carboniferous, and Permian — is a 
little more widespread and may therefore be worth a 
brief summary. 

Devonian 

According to Stauffer (Stauffer, C.R. 30), the 
Devonian of California is chiefly or perhaps entirely 
Middle Devonian, with a fauna not very different from 
that of the widespread Onondaga limestone of eastern 
North America and even closer to the fauna of the 
Caiceola beds (Eifelian) of the Rhenish Slate Moun- 
tains. 3 Notable, on the other hand, is the absence from 
the California Devonian strata of the Old Red sandstone 
facies of the system, which is widespread in Great Brit- 
ain and also in eastern New York. The Devonian record 
in California is thus only a fragment representing the 
most widespread division of the marine development of 
the system. In southeastern California the Devonian 
strata everywhere lie either upon Ordovician or upon 
unfossiliferous beds that may be Ordovician. In north- 
ern California, on the other hand, it lies in some areas 
upon fossiliferous beds of Silurian age. A mild "Cale- 
donian" disturbance is strongly suggested throughout 
the Cordilleran region. 

Permo -Carboniferous 

If we consider all the lands in the world, probably 
no group of rocks has been the subject of more, or more 
thorough stratigraphic studies than the post-Devonian 

3 Also called "Nevadan." 

8 But see also C. W. Merrlam (40). Note supplied the editor 
by A. O. Woodford, September 19, 19J». 



102 



Geologic History and Structure 



[Chap. V 



CARBONIFEROUS 

TAYLORSVILLE 

(northern sierra nevada, California) 



FEET 


500 

1000 

1500 

JOOO 

2500 



TRIASSIC 




I. I J LJ3 



,»»„» » l> . ,> »°»» 




ROBINSON 
FORMATION 

/REEVE 
-N .VOLCANIC S 

PEALE 
FORMATION 



</> 

D 
O 
IT 

UJ 

ii- 

Z 

o 

CD 

a. 

< 




SHOOFLY 
FORMATION 



DEVONIAN 




TAYLOR 



META-ANOESITE 



ARLINGTON 
FORMATION 



Paleozoic. Owing partly to their content of coal, oil, 
and gas, even their subsurface distribution is well known 
in many areas such as western Europe and eastern and 
central United States. It is thus not surprising that 
complex systems of classification have come into use and 
that they are undergoing continual modification. When 
we turn to the post-Devonian Paleozoic rocks of Cali- 
fornia, we find only a few formation names in use and 
not very many facts with which to characterize most of 
the proposed formations. Of the complex and interest- 
ing history deduced from the corresponding formations 
in the eastern United States there are few traces. No 
coal, no oil, no very definite suggestion of strong folding 
— nothing but limestone deposition occasionally inter- 
rupted by an influx of classic sediments, seems to have 
taken place during Permo-Carboniferous time in our 
supposedly mobile Cordilleran province, or at least in 
the part of it where conditions may be most readily 
studied. 

Longest known of the Carboniferous occurrences of 
California is the fossiliferous limestone northeast of 
Redding, which was recognized by John B. Trask (55) 
in 1855, and has been more intensively investigated 
since by J. S. Diller (06), J. P. Smith (16a, p. 28), and 
recently by Harry Wheeler (36). According to 
Wheeler, the Baird shale, which unconformably under- 
lies the McCloud limestone, is Upper Dinantian, or 
Mississippian ; the McCloud limestone is Uralian (upper- 
most Carboniferous, or Lower Permian) at base, pos- 
sibly Artinskian (Lower Permian) in the middle, and 
of unknown age, because of poor fossils, at the top. It 
is overlain by the Nosoni tuffs, possibly Kungurian 
(Middle Permian). 

The Carboniferous strata of the Sierra Nevada and 
of the San Bernardino Mountains are less understood 
faunally than the Redding section, and the supposed 
Carboniferous of the Coast Ranges may, of course, turn 
out to be of some other age. Better sections than any 
of those mentioned are found in the Inyo Mountains 
and farther east, but they will not be discussed here. 
Nothing will be said about the perplexing problems of 
Permo-Carboniferous paleogeography, and nothing more 
about the implied history, except to note Knopf's 
(Knopf, A. 29, p. 9) suggestion of a period of possible 
diastrophism near the end of the Paleozoic in the Mother 
Lode district. 

Triassic 

Rocks of Triassic age are known in the Santa Ana 
Mountains, at Mineral King in the Sierra Nevada, in 
Shasta County, and in the Inyo Mountains. Beds of 
more or less probable Triassic age are very widespread 
in coastal California and also in the eastern desert 
region. They include the Santa Monica phyllite and 
part of the Franciscan series. 

Before attempting to summarize the Triassic history 
of California, it may be interesting to recall what was 
happening during this time in the rest of the world. 
Aside from the uplands, which included most of the 
ancient shields, there were vast lowland areas of con- 
tinental deposition, such as western Germany, the 
Colorado Plateau, the eastern Rocky Mountains, and 
the Newark belt of eastern North America. Open seas 
were found nearly everywhere on those parts of the 
present continents where young, high mountains now 



Fio. 48. Columnar section of the Carboniferous in northern 
California. 



California's Recor d — R eed 



103 



exist; that is, in the Alps, the Himalayas, the Malay 
Archipelago, Japan, Alaska, and parts of the Pacific 
coast of North and South America. 

From the syntheses of Stille (Stille, H. 24), Kossmat 
(Kossmat, F. 36, pp. 132-149, Tafel IV, 1), and others, 
the geologic history of these mobile belts during Triassic 
time may be summarized as follows. After a period of 
moderately strong local folding at the close of the 
Paleozoic, sandy shales and similar beds of the Scythian 
stage were deposited in the geosynclines. During the 
succeeding (Anisic) stage, limestone deposition became 
more common and extended locally beyond the borders 
of the geosynclines into areas that remained generally 
continental, perhaps desert, during the Triassic period. 
In the next (Ladinic) stage, there was much crustal 
unrest, with local folding or warping and with much 
extrusion of lavas and tuffs, which became intercalated 
with the generally calcareous deposits of the geosyn- 
clines. These conditions continued during the Karnic, 
with widening seas, more cosmopolitan faunas, more 
limestone. Noric time had the widest seas, with deposi- 
tion of the purest and thickest limestone. It was fol- 



lowed by strong folding movements (early Cimmerian 
of Stille), and by deposition of dark marl and clay, the 
Rhaetic, latest Triassic or earliest Jurassic. 

That California shared in this history is suggested 
by Table 3, based on publications of J. P. Smith (32, 
p. 13, ff. ). So few and small are the remnants of 
Triassic deposits preserved in the State, however, and 
so complex and far-reaching the tectonic events since 
Triassic time, that there is little present prospect of 
ever knowing definitely the position of Triassic sea 
boundaries in the California province. 

It is nevertheless interesting and instructive to study 
the most nearly complete sections of the Triassic in 
California and Nevada, and to compare them with the 
sections of the Alps. The Lower Triassic shale, sand- 
stone, and impure limestone of the American west are 
not so different from the Scythic sandy shale of the 
Alps. The tuffs, shales, and andesitic breccias with 
interbedded chert of our Middle Triassic recall the 
varied sedimentary facies and plentiful volcanic rocks 
of the Alpine Ladinic ; while the Noric and Karnic 
limestones of the two widely separated provinces seem 



Table 2 



EUROPEAN TRIASSIC STAGES AND FOLDING MOVEMENTS, 
FROM KOSSMAT, GIGNOUX, STILLE, KAYSER, AND RENNGARTEN. 

All stages above the Anisic are correlated with the Keuper of extra-Alpine regions. 
The California Triassic is "Alpine", and is classified in the terms of the table; 
that of the Colorado Plateau and the Rocky Mountains is extra-Alpine and generally 
nonmarine, like that of western Germany and England. The dividing line between the 
two facies in southeastern Nevada and California is not far from the Colorado River. 


STAGES 


TYPICAN FORMATIONS 


COMMON FOSSILS 


Rhaetic (transitional) 


Kbssen marl 


Avicula contorta and 
bonebeds 


EARLY CIMMERIAN FOLDING (of Stille) 


Noric 
Karnic 


Main dolomite and Dachstein limestone 
Raibl and Hallatatt beds 


Turbo solitarius 

and many other 

fossils 


"LABINIAN" DIASTROPHISM AND VULCANISM (of Renngarten and Kossmat) 


Ladinic 

Anisic (Virglorian)=Musch- 
elkalk 

Scythic (Werfenian)=Bunt- 
sandstein 


Ramsau dolomite and Wetterstein limestone 
Nodular limestone of Reifling, etc. 

Werfen shales and gypsum 


Daonella lommeli, etc. 
Ceratites trinodosus 

Tlrolites, Pseudo- 
moootis, etc. 


PFALZIAN DISTURBANCE, mild and local 



104 



Geologic History and Structure 



[Chap. V 



to have much in common in addition to the fossils. 
Finally, the Rhaetic period saw the reintroduction of 
shale deposition in both areas. 

In Europe, according to Stille, the period of Triassic 
sedimentation was ended by the early Cimmerian folding 
movements, which, perhaps because of the fragmentary 
record, are not known to have affected the western 
United States. A very strong orogeny locally affected 
western Nevada not so long after the close of the Trias, 
but Ferguson and Muller (Ferguson, H. G. 37) believe 
that its climax came toward the end of the Lias (Lower 
Jurassic). If so, it is more nearly equivalent in time 
to Renngarten's "Donetz" phase (Renngarten, W.P. 
29) of the Caucasus than to the early Cimmerian of 
western Europe. 

Jurassic 

With the Jurassic, the sedimentary record of Cali- 
fornia becomes more voluminous, but scarcely more leg- 
ible, than it is for earlier periods. In the part of the 
State west of the crest of the Sierra Nevada, much of 
the pre-Cretaceous basement is more or less confidently 
assigned to the Jurassic, but the total quantity of 
dependable evidence is distressingly small. 

Thus the Sierra Nevada granite intrudes Kimmerid- 
gian and older rocks and therefore is, at least locally, 
post-Kimmeridgian. The granite and associated slates 
are unconformably overlain by flat-lying Upper Creta- 
ceous, which elsewhere overlies Lower Cretaceous and 
uppermost Jurassic with almost complete conformity. 
Thus the granite is considered to be pre-Portlandian, or 



at least pre-Cretaceous, by many geologists, but is classed 
as early Cretaceous by some. 

To consider a second example, the widespread Fran- 
ciscan series is commonly referred to the Jurassic. The 
published evidence is very meagre, however, and much 
of it erroneous. The famous Slate's Springs "Fran- 
ciscan" fossils are Upper Cretaceous (Nomland, J.O. 
32). Most of the Jurassic fossils found in supposed 
Franciscan rocks are thought by some authorities to 
have come out of the Knoxville, of which the relations 
to the Franciscan are still controversial. 

In the case of the Mt. Jura section of the northern 
Sierra Nevada, fossils are relatively plentiful and many 
faunal zones are represented, but the structure is so 
complicated that it can only be deciphered by relying 
upon a paleontologist's interpretation of the faunas. 

These examples show with sufficient clearness that 
the California Jurassic is more like that of the Alps 
than that of southwestern Germany or eastern England. 
It has the scarcity of fossils and complexity of lithology 
and structure that are characteristic of the geosynclinal, 
rather than of the epicontinental facies. Its paleo- 
geography and geologic history may thus be expected 
to teem with uncertainties and difficulties, instead of 
yielding clear and beautiful results as does the Jurassic 
of Great Britain. 

Before discussing the Jurassic problems of Cali- 
fornia, it may be interesting 'to recall something of the 
paleogeographic conditions and geologic events that 
characterized the period in other parts of the world. 



Table 3 



TRIASSIC ALPINE STAGES. CALIFORNIA AND WESTERN NEVADA. 
Data from J. P. Smith and S. Muller. 


RHAETIC 




Western Nevada 


NORIC 


Pseudomonotis zone 
Coral zone 


Genesee Valley, Brock Mountain, American 
River Canyon 

Shasta County (Muller considers some occur- 
rences Karnic) 


KARNIC 


Tropites subbullatus zone 
Juvavites subzone 

Trachyceras subzone 
Halobia rugosa zone 


Brock Mountain and Genesee Valley 

Brock Mountain, Genesee Valley, Feather 
River, and West Humboldt Range, Nevada 

Brock Mountain 


LADINIC AND ANISIC 


Ceratites trinodosus zone 
Parapopanoceras zone 


Pit River, California; West Humboldt Range, 
Nevada 

Inyo Mountains 


SCYTHIC 


Columbites zone 
Tirolites zone 
Meekoceras zone 


(Idaho) 
(Idaho) 
Inyo Mountains 


NOTE: The Mineral King Triassic is Upper, and that of Santa Ana Mountains, 
though tentatively referred to Middle Triassic by J. P. Smith, seems likely 
to prove Upper Triassic also, thinks S. W. Muller, on the basis of newer 
collections. 












California's Recor d — R eed 



105 



FEET 



MO 

IOOO 

1500 

2000 

2500 



TRIASSIC 

WESTERN NEVADA 

LOWER JURASSIC SUNRISE FORMATION 



RHAETIC 



_ NORIC (?) 



KARNIC 



LACHNIC (?) 
AND 
ANISIC 
(MUSCHEL- 

kalk) 



22SOO - 



_ SCYTHIC 



B 



lii H iP~ 



GABBS.FORMATION 



1 , 1,1 , 1 , 1 



/, /,/,/,/ 



/ // , / , 



III M I 



V / >i ' ' / ' r 



///// / LUNING FORMATION 

/ / / / / , CHIEFLY LIMESTONE AND 



I ' \ II f f DOLOMITE , WITH CORALS, 

1 i I i 'i I * ■ I AMMONITES, ETC. 







EXCELSIOR FORMATION 

EFFUSIVE AND PYROCLA3TIC 
ROCKS WITH SOME CHERT, 
BRECCIAS, AND RARE LIME- 
STONE BEOS CONTAINING A 
MUSCHELKALK FAUNA. 




CANOELARIA FORMATION 



PERMIAN SANDSTONE AND GRIT 



As suggested earlier, the Triassic ended with locally 
strong folding movements, the early Cimmerian of Stille, 
typically displayed in the Crimea. The Palisades dis- 
turbance of eastern North America may have taken place 
at the same time. Nearly contemporaneous with these 
disturbances was the peculiar Rhaetic transgression, 
which flooded marginal lagoons in many desert areas 
(England, Germany), and led to the making of thin 
but extensive bone beds. The typical marine fossil is 
Avicula contorta. The stage is generally considered 
Triassic by German stratigraphers, Jurassic by the 
French, and is sometimes treated as a separate unit by 
the British. 

The Lower Jurassic (Lias or Black Jura) was an 
epoch of deep and shallow seas, with shifting borders 
and uneven bottoms. Epicontinental deposits are 
chiefly dark shale and limestone; many coarse breccias 
occur in the geosynclines, such as the Alps and western 
Nevada. Very strong local folding took place near the 
close in western Nevada and also in the Caucasus Moun- 
tains. It was accompanied by andesitic outbreaks 
(northern Sierra Nevada), and in some areas (western 
Europe) by the uplift of certain deeply weathered old 
mountain masses covered with lateritic soil. Oil shale 
with beautifully preserved Icthyosaurs and Plesiosaurs 
is found in Swabia. Excellent Liassic ammonite zones 
occur in the mobile belts all over the world. 

The Middle Jurassic is also called the Dogger or the 
Brown Jura. Lower Middle Jurassic (Bajocian) is 
commonly transgressive and carries ferruginous sands 
and limestones in France and Germany. Upper Middle 
Jurassic (Bathonian) is regressive, with strong volcanic 
action in western North America. Strong post-Dogger 
folding is reported from East Africa and may have 
occurred in certain other places (Hennig, E. 37). 

The Upper Jurassic (Malm or White Jura) begins 
with the Callovian, a time of widespread seas in all 
Mesozoic geosynclines and in many adjacent lowlands, 
such as the Wyoming district, which lay east of the 
Cordilleran geosynclinal trough. The Callovian was 
followed, says Crickmay (Crickmay, C.H. 31, pp. 45, 
67), by very strong crustal movements, the Agassiz 
orogeny, in western Canada. After a middle Upper 
Jurassic transgression came the late Cimmerian dis- 
turbances of Europe and the correlative Nevadian fold- 



REDDING DISTRICT 



TRIASSIC 

(CALIFORNIA) 



•INYO MOUNTAINS 



■MOCK SMALC 
HOS3EUJU3 LA 








Flo. 49. Columnar sections of the Triassic of California. 



Fig. 50. Columnar section of the Triassic of Nevada. 



106 



Geologic History and Structure 



[Chap. V 



ing and plutonism of western North America. A later 
transgression, the Portlandian, lasted into the Lower 
Cretaceous in many areas, but was interrupted by an 
epoch of swamps in western Europe, and perhaps by 
folding in the Franciscan belts of California. 

Upper Jurassic time may be thought of as the period 
of the white limestone with many sponge and coral 
reefs and with the wonderfully fossiliferous lithographic 
limestone of Germany, of the upper oolites of England, 
of the peculiar greenstone-radiolarian chert — ophiolite 
series of Franciscan-like rocks that stretches from 
northern Italy to Asia Minor and the Oman region 
(Kossmat, F. 37; compare De Bockh, Lees, and Richard- 
son in Gregory, J.W. 29, pp. 133, 134). In California 
it may be thought of as the time of gold-quartz vein 
filling in the eastern mountains that were crumpled and 
thrust together toward the end of the period. Upper 
Jurassic in age, furthermore, are the famous Morrison 
beds of the Rocky Mountain region, from which many 
of North America's most stupendous dinosaurs have 
been disinterred. 

In contrast to most of North America, which has 
either no record of the Jurassic or a clear record of 
some small part of it, California has a complete record 
that is extremely difficult to decipher. In a small area 
of the northern Sierra Nevada is the Mt. Jura section, 
which has been hailed by competent authority as "the 
finest in America." To look at this section, however, 
is to realize how poor the others must be. It is cer- 
tainly not much like the fine sections of Swabia, of the 
Jura, of Lorraine, and of Dorsetshire. It is structurally 
so complex that a formation placed at its base by one 
of the two chief authorities is placed by the other 
authority at its top. 4 Most of the sedimentary rocks are 
so dense and dark-colored as greatly to resemble igneous 
rocks. The content of marine fossils in some of the 



« Interpretations of the Mount Jura Section: The writer has 
been requested to comment on the various interpretations of the 
Mount Jura section and since this subject lies outside the scope 
of the paper prepared by him for this bulletin, it is given here as 
a footnote. 

The original interpretation of Diller. based on many years' 
work, has been revised, reinterpreted, and greatly modified by 
Crickmay. but without the presentation of structural or carto- 
graphic evidence. Although the writer has not studied the region 
in detail and is hesitant in expressing a positive opinion he has 
visited the region a number of times and has collected fossils from 
a few localities. Since the beds are metamorphosed the preserva- 
tion of the fossils leaves much to be desired and the writer believes 
that the very precise age determinations made by Crickmay are 
not wholly justified by the usual condition of the fossils. Fossils 
were collected from the north and northeast sides of Mount Jura 
and submitted to a thoroughly qualified expert on the Mesozoic 
faunas but, because of the distortion due to crushing, he did not 
feel justified in assigning them to a definite position in the Jurassic. 

The writer can see no justification for the Combe formation 
of Crickmay and its assignment to the Tithonian. A number of 
days were spent collecting fossils from the area in which this 
formation is supposed to occur and in the surrounding region but 
the lithology is not as described. The Combe formation is a part 
of Diller's Foreman formation and the fauna appears to be even 
earlier than the Mariposa. There is no evidence for and much 
evidence against, both structurally and faunally, the statement that 
the Mount Jura section contains beds younger than the Kim- 
meridgian. 

The Trail formation was placed at the base of the Jurassic 
section by Diller and near the top by Crickmay although it is 
largely volcanic and contains no fossils. There is no evidence, 
either faunal or structural, for removing the Trail formation from 
its position at the base of the local Jurassic section. Evidence for 
its position at the base is the fact that, in the less disturbed eastern 
part of the region, it everywhere overlies the Triassic Hosselkus 
limestone ; on the western side, near the town of Taylorsville, 
lower Paleozoic is thrust eastward over the Jurassic, overturning 
it and concealing the lower part of the section beneath the thrust. 
The Lilac formation may be the lowest division exposed on the 
west but there is no evidence that it forms the base of the Jurassic 
section and is older than the Trail. The writer is of the opinion 
that Diller correctly interpreted the general features of both the 
structure and stratigrpphy. Note supplied the editor bii N. L. 
Talia/erro, September 12, /fljfl. 



formations looks distinctly out of place. The section 
is intruded by several bodies of igneous rock and many 
of the bedded members are more or less clearly pyro- 
clastic. 

In addition to the small Jurassic area of the Taylors- 
ville district (Mt. Jura), the Sierra Nevada has vast 
expanses of the important gold-bearing, granite-intruded 
Mariposa slate. It has yielded a few fossils that are 
certainly Upper Jurassic in age, some of them Kim- 
meridgian. There are some inconclusive reasons for 
supposing that the folding of the slate and its intrusion 
by granodiorite magma occurred about the end of Kim- 
meridgian time, contemporaneously with the late Cim- 
merian orogeny of the Caucasus and many other regions. 
Some authorities have — without much evidence — dated 
the folding a little later, however, either latest Jurassic 
or early Cretaceous. 

The two probably Jurassic formations of the Coast 
Ranges, the Franciscan and Knoxville, were formerly 
considered to be Cretaceous. Their relations to one 
another and to other older and younger formations 
has long been a matter of doubt and disagreement. The 
commonly accepted view at present is that the Fran- 
ciscan is Jurassic but pre-Portlandian, possibly includ- 
ing some pre-Jurassic strata; and that the Knoxville is 
Portlandian or Tithonian. The pre-Portlandian age 
of the Franciscan is now disputed by one of its most 
competent students, 5 however, and the Knoxville is still 
classed as Lower Cretaceous by the United States Geo- 
logical Survey (Wilmarth, M.G. 38, pp. 1115-1116). 

From a consideration of the most nearly complete 
Jurassic section of California, that of Mt. Jura, we 
may deduce the following series of historic events 
(Crickmay, C.1I. 33) : 

1. Deposition during the Lower Jurassic of dark- 
gray calcareous sandstone and shale (Lilac formation), 
followed by that of red, but highly fossiliferous arkose 
(Hardgrave). 

2. With the beginning of Middle Jurassic time — the 
period of iron-ore deposition in Lorraine and of strong 
local folding in western Nevada — the Fant andesites 
were erupted. They were followed in late lower Middle 
Jurassic by the deposition of fine-grained red marine 
tuff and blue-gray limestone (Thompson) and then, 
after an erosion interval, by the accumulation of nearly 
a thousand feet of generally fine-grained red and green 
fossiliferous arkose (Mormon). During lowest upper 
Middle Jurassic came the deposition, probably also in 
the sea, of the Moonshine conglomerate, shale, and tuff 
beds. The rest of the Middle Jurassic saw the accumu- 
lation of 700 ft. of coarse green agglomerate and red 
or green tuff, without fossils. 

3. At the beginning of the Upper Jurassic came 
the accumulation of a marine arkose, the Hinchman 
formation, then of a poorly fossiliferous agglomerate, 
the North Ridge, and of a light-gray shale, the Foreman. 
About the middle of this epoch there was renewed 
vulcanism, recorded in the thick, 900 to 1,900-ft. agglo- 
merate Cooks Canyon formation, with fossil wood. 
Micaceous sand and dark clay, with few fossils, were 
next deposited (Lucky S formation), to be followed 
by the accumulation of the Trail formation, 2,000 ft. 
or so of coarse conglomerate and tuff beds, without 



1 N. L. Taliaferro, oral communication. 






California's Recor d — R e e d 



107 



fossils. The latest Jurassic or Tithonian saw the 
accumulation of the fossiliferous Combe formation, a 
sandstone containing 1 granitic cobbles considered by 
Crickmay (33, p. 902) to be mid-Upper Jurassic in age. 
If the age of these cobbles is correctly determined, the 
Nevadian crustal disturbance, with its intense folding, 
metamorphism, and mineralization of the Mariposa 
slates and other formations, had receded so far into the 
past before the close of the Jurassic as to permit the 
plutonic rocks of that disturbance to be stripped of 
their cover and to have become subject to erosion. 

This Nevadian disturbance, post-Kimmeridgian and 
perhaps pre-Portlandian in age, is generally believed 



to have affected the Franciscan rocks of the Coast 
Ranges, though positive evidence is lacking. If the 
Franciscan turns out to be entirely Portlandian, as 
Taliaferro suggests, and if the disturbance turns out 
to be entirely pre-Portlandian, the belief will of course 
have to be given up. 

The Knoxville series was long considered to be 
Lower Cretaceous and to be included in the Shasta 
series. In recent years, however, the Knoxville has 
been commonly referred to the Upper Jurassic by 
stratigraphers, but not always separated from the 
Lower Cretaceous by those engaged in field mapping. 
According to F. M. Anderson (33), the Knoxville con- 



Table 4 



THE JURASSIC SYSTEM 
Data from Gignoux, Stille, and others. 



UPPER JURASSIC or MALM 
(White Jura) 



Purbeckian (Aquilonian) 

Portlandian (includes Solen- 
hofen beds) 



Tithonian of Alps, Lower- 
Volga stage of Russia, etc. 



WW LATE CIMMERIAN FOLDING (of Stille) 



Kimmeridgian 

Lusitanian 
Oxfordian 



Black marls in Dorsetshire, etc. 

Includes older Corallian 

Black marls of Oxford (strong transgression 

in Mexico) 



AGASSIZ OROGENY (of Crickmay) 



Callorian 



Formerly classed as uppermost Middle Jurassic 



STRONG TRANSGRESSION (Russia, etc.) 



MIDDLE JURASSIC or DOGGER 
(Brown Jura) 



Bathonian 
Bajocian 



Much of the iron ore of western Europe 
occurs in the Middle Jurassic 



LOWER JURASSIC or LIAS 
(Black Jura) 



Aalenian 

Toarcian 

Charmouthian 

Sinemurian 

Hettangian 



Much dark-colored shale, including 
oil-shale deposits and highly fos- 
siliferous beds, in these stages 



Rhaetic 



(Included by Gignoux in Lias) 



EARLY CIMMERIAN FOLDING (of Stille) 



108 



Geologic History and Structure 



[Chap. V 



tains a fauna dominantly of Aucellas, belonging to 
several Upper Jurassic horizons from Portlandian to 
Purbeckian (Aquilonian). 8 

CRETACEOUS 
Lower Cretaceous 

The Lower Cretaceous, except for an historical acci- 
dent, might have been called uppermost Jurassic. In 
the part of northwestern Europe where our stratigraphic 
system was originally set up, the strata referred to 
Lower Cretaceous consist of a varied series of marine 
and nonmarine clays and greensands lying between the 
Jurassic Oolites and the Cretaceous Chalk. Since most 
of the marine fossils are in the upper part of the series, 
they naturally resemble Chalk species more nearly than 
Oolite species. Thus, the whole series, except the basal 
beds at Purbeck, has come to be considered Cretaceous. 
There are, however, as Kossmat (Kossmat, F. 36, p. 
172) observes, many reasons for thinking of the Lower 
Cretaceous as merely a final division of the Jurassic, 
though it is hardly worth while to undertake to change 
long-established usage. 

With this condition in mind, it is not surprising to 
learn that in many places over the world, particularly 
in the geos3 r nclines, Upper Jurassic grades into Lower 
Cretaceous so imperceptibly that only an arbitrary line 
can be drawn between them. Marine Lower Cretaceous 



• Following Oppel, many writers adopt the term "Tithonian" 
for these uppermost Jurassic stages, or sometimes for the upper- 
most only. This term should, however, probably be restricted to 
the ammonite-rich deposits of Alpine type. The reason for using 
"Aquilonian" for the older "Purbeckian" Is apparently that the type 
Purbeck beds are largely nonmarine. 



was deposited, in general, in all the continents of the 
world where Mesozoic geosynclines existed, and the 
deposits are now found chiefly in young mountain ranges 
of folded Tertiary type. In the United States it has 
become customary to refer these deposits to the Coman- 
chean series, thus correlating them with the older part 
of. the Texas Cretaceous. The recognition of the 
Comanchean of Texas was undoubtedly an important 
accomplishment, but since the Comanchean series in- 
cludes only the upper part of the Lower Cretaceous, 
there is not much probability that the term will ever 
attain world-wide usage. Though recognized many 
years ago, the Lower Cretaceous of California has been 
a stumbling-block to stratigraphers. At present the 
views of F. M. Anderson (38a) are beginning to prevail, 
and the publication of his recent memoir should acceler- 
ate the process. In much of the Coast Range area south 
of San Francisco, however, the Lower Cretaceous and 
Knoxville strata have not yet been discriminated care- 
fully and will need a vast amount of additional study 
before their relations are well understood. 

As Table 5 illustrates, Dr. Anderson finds that the 
Lower Cretaceous strata (Shasta series) are divisible 
into two groups; an older or Paskenta group, and a 
younger Horsetown group. The Paskenta group cor- 
responds to the Infra- Valanginian and Valanginian 
stages in the European sequence; its fauna consists 
largely of Aucellas, and in part of cephalopods, and its 
lithology is dominantly shaly with some sands and 
locally with basal conglomerates. In the mountains 
west of Coalinga, the Paskenta group contains a fossilif- 



Table 5 



LOWER CRETACEOUS OF CALIFORNIA (Shasta series), 

Its major subdivisions, and their relation to the European standard, 
adapted from F.M. Anderson (1938). 


UPPER 

CRETACEOUS 


Chico 
series 


Danian to 
Upper Albian 






Unconformity 


LOWER 
CRETACEOUS 


Shasta 
series 


Albian 


Hulen beds 


Concretionary sandy shale, good 
cephalopod fauna in Cottonwood 
district, northern California 


Aptian 

Barremian 

Hauterivian 


Horsetown group 


Upper members mostly shale, locally 
good cephalopod faunas 

Lower member (Ono zone) shale, sand- 
stone, conglomerate, with rich ceph- 
alopod fauna 


Valanginian 
Infra -Valanginian 


Paskenta group 


Sandy shale, locally conglomeratic 
at base, faunas largely of Aucellas, 
with local cephalopods 


UPPER 
JURASSIC 






Knoxville 





- 



California's Recor d — R eed 



109 



erous basal conglomerate and unconformably overlies 
Knoxville strata. The Horsetown group was recognized 
very early in northern California and was long supposed 
to be absent south of the Mt. Diablo district. It has 
recently been found much farther south, and will prob- 
ably be found at least as far south as the north edge 
of the Transverse Ranges. The Horsetown group is 
shaly or sandy, locally with a coarse basal member, the 
Ono zone, which carries a rich cephalopod fauna of 
Hauterivian age. The upper members of the Horse- 
town range upward in age to upper Middle Aptian ; 
they are largely shales and carry good local faunas of 
cephalopods. They are overlain by the Hulen beds, 
sandy and concretionary, fossiliferous, and Albian in 
age. Unconformably above the Hulen beds comes the 
Chico series, Upper Cretaceous shale and sandstone. 

Upper Cretaceous 

Rocks of undoubted Upper Cretaceous age are very 
widespread in the California Coast Ranges. In some 
places, however, the lower boundary is uncertain, and 
in many places there is at least a little doubt as to the 
exact location of the upper boundary. Much of the 
uncertainty is due to inadequate study of the fossils, 
or to local poverty of fossils. Even where good fossils 
exist and have been carefully collected and studied, the 
correlation with the Danian-Montian horizons of 
Europe offers some difficulties. 



During the last few years there has been a marked 
increase of interest in the California Cretaceous as a 
possible bearer of oil and gas deposits. The strata are 
therefore being actively mapped and studied at present, 
and will probably soon be better understood. In the 
hope of aiding this increase of knowledge, F. M. Ander- 
son has recently compiled 7 a stratigraphic chart, based 
on fossils collected during many years. Within the 
beds commonly classed as Chico in years gone by, he 
now recognizes faunas ranging in age from Upper 
Albian to Danian, with a stratigraphic and faunal 
break about at the base of the Senonian. His results 
suggest that the Upper Cretaceous history of the Coast 
Ranges, when it is worked out, will have many analogies 
with that of the Tethyan districts of the Old World, 
with a "Cenomanian" transgression, a "Subhercynian" 
disturbance, and an Upper Senonian or Maestrichtian 
epoch of non-clastic deposition. The work of Popenoe 8 
shows, furthermore, that at least one phase of the 
"Laramide" disturbance at the end of the Mesozoic 
took place between uppermost Chico and Martinez time, 
as those terms are used in southern California. 

Marine deposits of the Upper Cretaceous underlie 
much of California west of the Sierra Nevada and the 



7 Anderson. F. M. Chart and talk presented before Cordllleran 
Section of Geological Society of America, April 1, 1938. 

8 Popenoe, W. P. Oral communication concerning an area on 
the west slope of the Santa Ana Mountains. 



Table 6 





UPPER CRETACEOUS (Chico series) OF 
PROPOSED CLASSIFICATION AFTER F.M 


CALIFORNIA, 
ANDERSON. 


Thickness GiTen 


Under Heading "feet" Are Dr. Anderson's Estimates For The Divisions 
Found In The San Joaquin Valley. 


EUROPEAN STAGES 


FORMATIONS 


FEET 


FOSSILS 


Danian-Maestrich tian 


Orestimba group 

Volta, Gaxsas, 
Qui n to, and 
Moreno 


5,000 ± 


Baculitee occldentalis . Phylloceras, 
many diatoms and foraminifera 




Panoche group 
Los Gatos fm. 


2,400 


Parapachydiscus catarinae, Desmoceras, 
Hauericeras, etc. 


Campanian 


Joaquin fm. 


3,700 


Inoceramus sakhalinensis, Phylloceras 

garftantuum, etc. 


Santonian 


Butte fm. 


4,000 


Mortoniceras templetoni, Paleatractus 
crassus, etc. 


Coniacian 


Yolo fm. 


4,500 


Placenticeras pacificum, Baculites 
inornatus, Thyasira cretacea, etc. 


Co 


iglomerates and reworked fossils in mai 


1/ sections 


Turonian 


Pioneer group 
Bellavista fm. 


3,325 


Prionotropis bakeri, Oregoniceras 
oregonense, e£c"! 


Cenomanian 


Gains fm. 


3,975 


Turrilites oregonensis, Acanthoceras 

cf. cumin gt on i, Puzosia jimboi (noT.) 


Uppermost Albian 









110 



Geologic History and Structure 



[Chap. V 



Peninsular Ranges. Even in the Klamath Mountains though thin or thick beds of more or less sandy shale 

they are found in patches, generally of conglomerate make up the greater part of the mass. A thick deposit 

and coarse littoral sandstone. In most Coast Range of brownish or purplish, more or less siliceous, locally 

exposures sandstone occurs prominently and huge diatomaceous and foraminiferal shale (Moreno forma- 

conglomerate lenses are common and conspicuous, tion) forms a conspicuous upper member along the east 



Jands I. mud 



Kn ox v i lie Shasta Opposition 

fiouldtrs sand mud 




I After Nevadian folding 




.Fint detritus 



I After Mid-Cretaceous folding 



&ABILAN 
MESA 



Present Conditions 
Vr/InSE "HILLS*" SAH J 0HQU1K VALLEY 



SIERRA NEVADA 
FOOTHILLS 




x x x x 

X 

X x * x x x 

JE After Coast Range Folding 






Fio. 51. Diagram of Jurassic-Lower Cretaceous paleogeography, showing development of structure in the Great 

Valley. 






Cam f o u ma's Recor r> — R eed 



111 



slope of the Diablo Range from Alt. Diablo south to 
Coalinga. It is interesting as being the only member 
of the California Cretaceous that suggests, even 
remotely, the Chalk of certain other Cretaceous areas. 

Marine fossils of many types are found in many 
exposures of the Cretaceous, but good collecting locali- 
ties are few and thick sections with fossils distributed 
throughout are almost nonexistent. One of the best is 
the Santa Ana Mountains section of southern California, 
which represents only a fraction of the Upper Creta- 
ceous. 

As Pack and English recognized (Pack, R. W. 14, 
p. 127) long ago, and as later workers have repeatedly 
corroborated, the Chieo beds of the Diablo Range in 
several places approach 2. r >,000 ft. in thickness. They 
are locally unconformable on Lower Cretaceous, and 
have several horizons at which thick lenses of coarse 
conglomerate occur locally. The significance of these 
conglomerate horizons has never been made clear by 
detailed mapping and collecting, but it is not improbable 
that they may be found to separate the formation into 
several distinct units. Very recently, as a matter of 
fact, P. M. Anderson (38a) has stated that he finds 
persistent coarse strata at the base of the Chico — Upper 
Albian to Cenomanian — and at a horizon within it — 
Coniacian. A striking peculiarity of these conglomerate 
lenses is that they seem to die out eastward toward the 
San Joaquin Valley. 

The Marysville Buttes Cretaceous is generally fine- 
grained, and even the outcrops along the Sierra Nevada 
foothills are sandy rather than conglomeratic. Deep 
wells drilled in the central valley area have penetrated 
great thicknesses of Cretaceous shale, but even the Pure 
Oil Company's Chowchilla Ranch well, drilled near the 
center of the Valley a few miles south of Merced, and 
carried to granitic basement rock at about 8,300 ft., 
found above the basal conglomerate of the Chico only 
shale and fine-grained sandstone. A western source thus 
seems to be indicated for the pebbles of the conglomerate 
lenses. 

Since the pebbles of the Chico conglomerates are 
only in minor part of Franciscan derivation, and since 
the only granitic area now emergent west of the San 
Joaquin Valley is the narrow belt lying between the 
San Andreas and Nacimiento fault zones, it seems 
inevitable at first glance that this narrow belt, Salinia. 
must have contributed to the Upper Cretaceous detritus. 
Further study shows, however, that a considerable part 
of Salinia itself is covered with coarse Upper Cretaceous 
strata thousands of feet thick ( Reiche, P. 37, p. 137 ft'.). 
This condition may not have existed on the broader, 
northwestern continuation of Salinia that is now sub- 
merged beneath the Pacific Ocean, but this area is a 
long way from the north Coalinga region where the 
most striking masses of Chico conglomerates are now 
known. 

Interesting in this connection is the question of the 
age of the granite found beneath the Chico of the 
central San Joaquin Valley in the well drilled near 
Merced. In appearance this rock resembles the Jurassic 
granodiorite of the Sierra Nevada. If it is Jurassic in 
age, it must have been intruded into Jurassic and older 
strata during the Nevadian revolution — post-Kimmerid- 
rrian. and pre-Cretaceous. The cover must then have 



undergone erosion during latest Jurassic and Lower 
Cretaceous so as to expose the coarse-grained plutonic 
mass by the time of the latest Upper Cretaceous trans- 
gression in the central Valley area. Where did the 
products of this erosion and of the erosion of the Sierra 
Nevada mass go? If they were carried eastward they 
stopped only in Utah, since Lower Cretaceous deposits 
do not occur in the intervening area. If they were 
carried toward the west, they could have come to rest 
in the northern Franciscan area or farther west, where 
deposition was taking place generally during the period 
in question. Perhaps we may be justified in seeing in 
the products of this great period of post-Jurassic and 
pre-Upper Cretaceous erosion, a probable source for 
the thick Lower Cretaceous deposits of the California 
Coast Ranges. 

If so, and if the unconformity between Lower and 
Upper Cretaceous turns out to be widespread and of 
considerable magnitude, we may perhaps then go one 
step farther and see in the folded and uplifted Lower 
Cretaceous strata of the Coast Ranges the desired 
western source for the immensely thick Upper Creta- 
ceous deposits of the west edge of the San Joaquin 
Valley. Opposed to this hypothesis is the prevalent idea 
that the Knoxville Lower Cretaceous deposits are gen- 
erally finer in grain than those of the Upper Cretaceous. 
Further studies of the distribution and character of 
Lower Cretaceous and Knoxville strata will be needed 
to determine this point. In any event, it now seems 
clear that the width of the belt of very thick Upper 
Cretaceous is very much less than might be guessed at 
first sight; if so, the problem of finding a source for 
these sediments is somewhat lessened. 

The Cretaceous marine faunas of California are 
partly Boreal and partly Indo-Pacific in character. 
Ammonites, baculites, and pelecypods are prominent 
among the larger invertebrates, foraminifera among the 
smaller ones. A few large reptiles have recently been 
found in the Moreno shale. Diatoms are locally prom- 
inent in the formation. Fragments of wood and leaves 
are common in many Cretaceous beds, but identifiable 
plant material seems to be scarce. 

The only nonmarine Cretaceous that outcrops in 
California is the red Trabuco conglomerate, apparently 
barren of fossils, that lies at the base of the Chico beds 
in the Santa Ana Mountains. Recognizable volcanic 
rocks are limited to probable ash beds in the Moreno 
shale. 

Periods of strong folding seem to have occurred only 
at the beginning and end of the period. The post- 
Turonian orogeny (Stille's Subhercynian), supposedly 
important for the Andes and perhaps also for Mexico, 
is suggested for the Coast Ranges only by the occurrence 
of the conglomerate mentioned by Anderson as charac- 
terizing the various sections in which he has found 
faunas of Coniacian age. Its traces may be recognized 
more widely when the great areas of Chico deposits are 
carefully mapped. The importance and extent of 
Austrian (pre-Cenomanian) and Laramide disturbances 
are also in need of additional study; but both disturb- 
ances are clearly more important than anybody has sus- 
pected until very recently. 

Rocks of Upper Cretaceous age are not noted for 
their mineral content. Cold placers have been worked 



112 



Geologic History and Structure 



[Chap. V 



in Cretaceous gravels in the Klamath Mountains and 
elsewhere. At New Idria, part at least of the quicksilver 
ore is taken from Upper Cretaceous sandstones, but the 
mineralization is post-Cretaceous. Oil is produced from 
sands within the Moreno shale in the very small Oil City 
field. Gas comes from Cretaceous rocks in the Tracy 
gas field, and perhaps from uppermost Cretaceous in 
the McDonald Island gas field ; also, gas is found in the 
Cretaceous of Marysville Buttes and elsewhere in the 
northern Sacramento Valley. Although none of these 
occurrences of oil or gas compares in importance with 
many Tertiary occurrences, the possibility of discover- 
ing other and more important Cretaceous deposits is not 
exhausted. During the next few years, as a matter of 
fact, the oil and gas possibilities will almost certainly 
be investigated more thoroughly than ever before. One 
certain outcome of this investigation will be the possi- 
bility of writing an account of Cretaceous deposits, their 
stratigraphy, structure, paleogeography, and geologic 
history, that will make such an account as the present 
one seem hopelessly antiquated and full of errors. 

TERTIARY 
General Statement 

About a century ago it became customary to divide 
the Tertiary of the world into Eocene, Miocene, and 
Pliocene divisions. Lyell (33, p. 53, ff.) even had two 
Pliocenes, an older and a newer, but the newer eventu- 
ally came to be called Pleistocene, following Edward 
Forbes' use (1846) of a term (Wilmarth, M.G. 25, p. 
48) invented by Lyell to designate something else. In 
1854 Beyrich described as Oligocene (Wilmarth, M.G. 
25, pp. 53-54) some transitional Eocene-Miocene deposits 
in West Germany, and 20 years later W. P. Schimper 
used the term Paleocene for earliest Tertiary strata of 
France and elsewhere (Wilmarth, M.G. 25, pp. 54-56). 
Since the difficulties in making long-range correlations 



increase rapidly when we turn from pre-Tertiary to 
Tertiary strata, there is no certainty that the California 
use of such terms as Oligocene and Miocene coincides 
exactly with the use current in western Europe. The 
terms are nevertheless common in California, though 
there is much uncertainty as to the proper use of two, 
Oligocene and Paleocene. 

In the following discussion I find it convenient to 
divide the Tertiary deposits into four groups, and to 
make the dividing lines at places other than those com- 
monly used. I shall therefore revert to another early 
classification of the Tertiary, dividing it in the middle 
and calling the two parts Paleogene and Neogene 
(Kayser, E. 24, p. 230) ; each of these groups I shall 
further divide into Upper and Lower. These terms are 
not meant to replace those in common use, but they will 
be useful in this discussion for two reasons : first, because 
they allow the Tertiary to be split at horizons that are 
widely recognizable throughout the Coast Ranges; sec- 
ond, because the groups so produced have a considerable 
degree of unity and thus permit some simplification of 
the Tertiary history of the Coast Ranges. 

Base of the Tertiary 

The Cretaceous-Tertiary contact is locally an angular 
unconformity, with Paleocene, later Eocene, or still 
younger strata forming the superjacent member. In 
some localities, as in the northern San Joaquin Valley, 
an unconformity is absent and there is uncertainty as 
to the age of unfossiliferous sandy strata lying between 
fossiliferous Eocene and Cretaceous. There is even a 
possibility that part of the Moreno formation, as 
mapped, may belong in the early Paleogene. 

Lower Paleogene 

The most important and persistent negative areas of 
the Lower Paleogene were three embayments that 
developed at the beginning of the Tertiary and persisted 



Table 7 



TYPICAL FORMATIONS IN CALIFORNIA 


AGE ASSIGNMENTS 


CURRENT USAGE 


GROUPING BY R.D. REED 


Upper San Pedro 


Upper Pleistocene 


Pleistocene 




Lower San Pedro, Saugus, Tulare 
Etchegoin, Pico, Repetto 


Lower Pleistocene 
Pliocene 


Upper Neogene 


NEOGENE 


Santa Margarita, Monterey, Modelo, 
Topango, Temblor 


Upper and Middle 
Miocene 


Lower Neogene 


Vaqu«ro«, Temblor, Pleito, San Lorenzo, 
San Ramon 


Lower Miocene and 
Oligocene 


Upper Paleogene 


PALEOGENE 


Kreyenhagen, Tejon, Capay, Domengine, 
Meganos, Martinez, lone, Poway 


Eocene and Paleocene 


Lower Paleogene 



Tertiary and Pleistocene formations of California. 






California's Recor d — R eed 



113 



throughout. They have been called the San Joaquin, 
Santa Barbara, and Capistrano embayments. In addi- 
tion, there were several straits ; among them the Markley 
strait or trough north of Mt. Diablo, and the San Benito 
trough stretching from the Vallecitos area (north of 
Coalinga) to the vicinity of Half moon Bay. Some low- 
land areas adjacent to the troughs and embayments were 
also flooded during more or less of the Paleogene epoch. 
Such areas have thinner, more discontinuous sections of 
rock than those classed as embayments or as troughs. 
The chief upland areas were Mohavia — greater by 
far in area than all the others combined ; parts of Salinia 
and Anacapia, and three areas that have been called 
"uplifts": the Diablo, San Rafael, and Catalina uplifts. 
The last-named area is now so widely covered by the 
ocean that any conclusions about its history must be 
based largely on indirect evidence. The two others, 
being on land, are much better known. They were 
emergent at the beginning of the Lower Paleogene but 
became partly submerged later on. The San Rafael 
uplift locally became stripped of its Cretaceous cover 
during the epoch, and furnished Franciscan detritus to 
adjacent parts of the sea. The Diablo uplift, on the 
other hand, seems to have retained its Cretaceous cover, 



except in a few small areas, until during, or perhaps 
near the end of, the Upper Paleogene. 

Among the formations referred to Lower Paleogene 
are several that throw interesting light upon problems 
of paleogeography and geologic history. Among them 
are the Martinez sandstone and conglomerate; the coal, 
leached clay, glass sand, orbitoid limestone, and reddish 
marine shale of the middle Eocene ; the Kreyenhagen 
siliceous shale, fossiliferous Tejon sandstone and sandy 
shale, Poway conglomerate, and continental red beds of 
the lower Sespe, all of upper Eocene age. Almost the 
only volcanic rocks are more or less altered ash beds 
in the Simi Valley and in the Kreyenhagen shale area 
of the Coalinga district. Compared to the Coast Ranges 
of Washington, where thick sheets of Eocene basalt are 
conspicuously present, the California Coast Range 
Eocene deposits are remarkably free from inclusions of 
igneous rocks. 

With reference to the sedimentary formations, even 
a brief examination shows that the older of the Lower 
Paleogene beds are generally coarse, variable in lith- 
ology, and of restricted distribution. Those with good 
marine faunas are, in fact, limited to a few small 
areas. During the middle of the epoch the beds 
deposited were generally finer in grain and more uni- 




LOWER PALEOGENE 



Fio. 52. (See Fig. 55 for explanation). Paleogeographic map of the lower Paleogene 



114 



Geologic History and Structure 



[Chap. V 



form in character — Capay silts, Domengine and lone 
sandstone — and were spread over earlier Paleogene 
deposits as well as considerable areas that had not been 
covered by them. Toward the end of the epoch the 
areas of deposition remained large but the facies repre- 
sented became highly varied. They include the Poway 
conglomerate, lower Sespe continental red sandstone, 
Coldwater and Tejon marine sandstone and sandy shale, 
and the Kreyenhagen siliceous shale. 

Faunas and floras as well as lithology suggest clearly 
that Lower Paleogene, particularly the middle of the 
epoch, was a time of considerable warmth and humidity. 
Earlier and later parts of the epoch are less distinctly 
tropical, and the red beds of the lower Sespe have even 
been considered evidence of aridity, though a considera- 
tion of their mammalian remains has shown that this 
idea is erroneous. 

From the point of view of their economic deposits 
the Lower Paleogene formations are or have been 
important for coal, oil, gas, pottery clay, glass sand, 
and gold. Owing to the poor grade of the coal beds 
and their complex structure, production has now ceased, 
but may become important again at some time in the 
future. Oil and gas are produced at present chiefly 
in the Simi Valley and in the Coalinga region, gas alone 



at Rio Vista and perhaps McDonald Island. Many 
additional deposits may be found in the future. Pottery 
clays and glass sands come from those areas in which 
the middle Eocene lone formation crops out. Gold 
placers are found in the Sierra Nevada foothills in 
rocks of middle Eocene age. Pottery clays, glass sands, 
and gold fragments are all products of the tropical 
weathering conditions of the middle Eocene. 

Upper Paleogene 

Upper Paleogene time saw a great increase in size 
of land area, considerable parts of which received thick 
deposits of Sespe type. Marine deposits seem to have 
accumulated chiefly in a part of the San Joaquin embay- 
ment and near it. Later on in Vaqueros time, the sea 
invaded much of the Sespe lowland, and continued to 
spread until the end of the epoch. It finally became a 
very widespread body of water, in which accumulated 
muds carrying foraminifera of the shallow-water type. 

The conditions in the San Joaquin embayment dur- 
ing the early part of the epoch are particularly inter- 
esting because they seem likely to have been favorable 
for the genesis of oil. The time was that of the depo- 
sition of the upper (Oligocene) part of the Kreyen- 
hagen shale, which graded into marine sandstone toward 




UPPER PALEOGENE 



Fig. 53. (See Fig. 55 for explanation). I'aleogeographic map of the upper Paleogene. 



California's Recor d — R e e d 



115 



the south and southwest margins of the embayment. 
Farther to the southwest lay the great areas of deposi- 
tion of the Sespe red beds. The communication with 
the western ocean was along the San Benito trough. 
The embayment was thus semi-enclosed, and its waters 
were probably deeper than those of the trough, where 
mollusk-bearing sandstone and siltstone are well rep- 
resented. A deep, semi-enclosed sea basin, becoming 
gradually filled with highly organic silt and ooze, the 
embayment had, at that time, several features sugges- 
tive of the Black Sea at the present. Bottom muds in 
the embayment may thus have been deficient in oxygen, 
like those of the Black Sea, and their organic content 
may have become bituminized rather than completely 
oxidized. 

As is well known, many geologists have long favored 
the view that the Kreyenhagen shale is the source of 
the oil in the Coalinga oil fields. The favorable evi- 
dence was derived from local stratigraphic conditions 
observed in the Coalinga district, and may now be 
supplemented by the paleogeographic considerations 
summarized in the preceding paragraph. 

Despite the increase in size of land areas at the 
beginning of the Upper Paleogene, the general arrange- 
ment of uplands and basins persisted as in the Lower 



Paleogene. The Santa Barbara embayment, though 
above sea level during the Sespe, was strongly negative 
as shown by the great thickness of its Sespe deposits. 
A part of it, the Oakridge uplift, ceased to subside so 
rapidly at the end of the Sespe, but the remainder con- 
tinued to subside throughout the Tertiary at a rat. 1 that 
has given this area Miocene and Pliocene deposits as 
thick as any that are known in any part of the world. 

Salinia was generally emergent at first, but later 
subsided irregularly, perhaps with the development of 
fault troughs of deposition. The Diablo uplift, prob- 
ably the Catalina uplift, and at least the eastern end 
of Anacapia were also upland, and so was a vast area 
of Mohavia, though a basin of continental deposition 
is known to have developed at that time where the 
eastern edge of Death Valley now lies. Several other 
similar basins may have come into existence on Mohavia 
toward the end of the epoch by the time that the depo- 
sition of coarse clastic deposits had ceased over the 
greater part of the Coast Range embayments. 

In contrast to the Lower Paleogene conditions, Upper 
Paleogene time began with facies heterogeneity and 
concluded with a marked degree of homogeneity. 
Sespe-upper Kreyenhagen time (early Upper Paleogene) 
was succeeded by the epoch of Temblor- Vaqueros sand- 




LOWER NEOGENE 



Fig. 54. (See Fig. 55 for explanation). Paleogeographic map of the lower Neogene. 



116 



Geologic History and Structure 



[Chap. V 



stones, and this by the era of the Media and Rineon 
clay shales (late Upper Paleogene). Volcanic activity, 
on the other hand, was weak or absent at first but 
increased sharply toward the end of the epoch and 
reached a maximum approximately at the very end. 

The climate was apparently warm throughout this 
epoch, but the amount of rainfall certainly decreased 
locally and probably everywhere in coastal California. 

The most important economic product of the Upper 
Paleogene strata is undoubtedly oil. The combination 
of basal organic shales and overlying coarse marine 
sandstones has given rise to several large and valuable 
accumulations about the margins of the San Joaquin 
embayment, and more complicated relations have led 
to some important accumulations in comparable horizons 
in coastal California. Coalinga and Kettleman Hills in 
the former area, and the Elwood and/South Mountain 
fields in the latter, are good examples. 

Transition, Paleogene to Neogene 

The transition from Paleogene to Neogene comes 
within the Miocene, as that term is commonly used in 
California. It comes at the base of the "button bed" 
(Anderson, F.M. 05), uppermost member of F. M. 
Anderson's type Temblor of Carneros Creek in the 



Temblor Range; at the base of the "third zone" in 
the producing formations at Kettleman Hills; approxi- 
mately at the contact of clay shale and siliceous shale 
members of the Santa Barbara Miocene beds ; at the 
base of the Topanga formation of the Santa Monica 
Mountains ; and probably at the base of the San Onofre 
breccia, southeast of the Los Angeles Basin. In the 
terminology of R. M. Kleinpell (34a; 38), which is 
rapidly coming into general use in California, the transi- 
tion comes between the Saucesian and Relizian stages, 
or between lower and middle Miocene. 

The importance of this horizon for historical geology 
was not fully recognized by the pioneers in Coast Range 
geology. The reason is simple; the pioneers were 
dependent upon the larger invertebrates for correlations, 
and the larger invertebrates do not seem greatly to 
respect this boundary. Some of the Temblor index fos- 
sils occur both above and below it. The type Temblor, 
as suggested above, though chiefly Upper Paleogene, 
includes at the top a calcareous sandstone, or "reef 
bed," that belongs to the Lower Neogene. This mem- 
ber, the "button bed," was early recognized to be 
locally transgressive, however, and additional field map- 
ping has added greatly to the number of localities in 
which this condition can be observed. A very striking 




EXPLANATION 

erna 

PM_EOG£OG«APHIC MAPS 




NUMKOWMK LAM> AJVAS 



^MAftiNC MClIt OF TH VM1ITI 



UPPER NEOGENE 



Fig. 55. Paleogeographic map of the upper Neogene. 



California's Recor d — R bed 



117 



one, in the central part of the San Rafael Mountains, 
has been described and figured in an earlier publication 
(Reed, R. D. 36). The button bed horizon is one of 
the few horizons in the Coast Range Tertiary at which 
fossiliferous, more or less pure limestone lenses are 
common. Even the button bed and the reef beds of 
which it is a member, may be properly described as 
very sandy limestone. 

Lower Neogene 

In a broad way, the Lower Neogene may be described 
as the period of deposition of siliceous shales of the 
Monterey type. It is true that deposits of this type 
began in uppermost Paleogene in the Maricopa district, 
and that they persisted into Upper Neogene in such 
areas as the Santa Maria district, but the general rela- 
tion is clear and striking. To an almost but not quite 
equal degree, the Lower Neogene is also the time of 
eruption of Tertiary volcanic rocks in the Coast Ranges. 
Similarly, it is the time during which accumulated 
nearly all the masses of coarse Franciscan detritus of 
which the San Onofre breccia and the Big Blue are 
the best-known examples; and it is the time of accumu- 
lation of the great majority of Tertiary nonmarine basin 
deposits of the Mojave Desert area. It is the time, 
finally, of the most striking indications of orogenic 
activity to be found in the Tertiary deposits of the 
Coast Range province. 

That all these exceptional phenomena are interrelated 
is an almost inevitable conclusion. Thus, the basin 
development and filling on Mohavia and Salinia served 
to restrict the entrance of non-Franciscan detritus into 
Coast Range seas. The great outpourings of volcanic 
rocks and accompanying liquids and gases, and perhaps 
the weathering of the rocks, presumably helped to 
determine the siliceous type of shales deposited in some 
of the embayments, perhaps in part by determining 
the type of life that thrived within their waters. Oro- 
genic and epeirogenic movements in the restricted 
upland areas gave rise to the local supplies of coarse 
Franciscan detritus, and later, no doubt, to the supplies 
of coarse granitic sand that accumulated as the Santa 
Margarita sandstone. 

The widespread seas of varying depth, with a large 
content of organic matter in their quieter parts, were 
apparently favorable for oil genesis at certain times 
and places. The Santa Maria Basin seems to be one 
of the places. In eastern California some of the volcanic 
intrusions carried valuable deposits of gold, silver, and 
tungsten ores. And in some of the Coast Range basins 
deposits of exceptionally high-grade diatomite accumu- 
lated. 

A study of the paleogeographic map will show that 
the major basins of the Coast Ranges continued to 
subside during the Lower Neogene at a greater rate 
than the areas of the Tertiary uplifts, even though the 
latter were largely submerged during part or all of the 
epoch. On Anacapia and Salinia, however, Lower 
Neogene deposits accumulated in some newly-formed 
basins in thicknesses comparable to those of the 
embayments. 

Upper Neogene 

The change from Lower to Upper Neogene corre- 
sponds to the change from Miocene to Pliocene in the 



ordinary stratigraphic classification. ,'It was a time 
when the "uplifts" reasserted themselves, as did parte 
of Salinia, Anacapia, and Mohavia. /In the last-named 
province basin-formation and filling seems to have 
ceased for a time, and external/ drainage was reestab- 
lished. The sea persisted at first in some of the newly 
formed coastal basins, such as the Santa Maria and Paso 
Robles basins, but in nearly all eases the basins became 
much smaller than they had formerly been. Even in 
the three great embayments only the landward ends 
remained strongly negative : the Maricopa, Ventura, 
and Los Angeles basins. The increase in area and ele- 
vation of the uplands, and the diminution in size of 
the areas of deposition led to an increase in the clastic 
content of the sediments and to a cessation of deposition 
of siliceous shale of the Monterey type. 

The smaller size of basins of deposition and poorer 
communication between those that persisted led to more 
provincial faunas. Even at the present time, with all 
the paleontological work that has been done upon larger 
and smaller marine Pliocene fossils, it is possible to 
correlate deposits of the San Joaquin and Santa Bar- 
bara embayments only in a general way. The Santa 
Barbara and Capistrano embayment deposits are readily 
correlated by means of microfossils, but the succession 
of microfaunas is generally recognized to be a succes- 
sion of similar facies. Many of the most diagnostic 
forms of the several faunas are still living offshore from 
the coast of southern California. If we use the present 
distribution of these faunas as a means of interpreting 
the conditions that existed in the Upper Neogene, we 
conclude that the major coastal basins were some thou- 
sands of feet deep in lower Upper Neogene and that 
they became gradually shallower until near the end of 
the epoch when, as has long been known, they were 
above sea level. The history of the younger basins, such 
as the Santa Maria and Paso Robles basins, seems not 
to have followed that of the major basins in all details, 
but additional work is needed in each of them before we 
can be sure just what happened. 

The bottom relief during early Upper Neogene may 
have been an important factor in producing conditions 
favorable for the accumulation of the mother-rock of 
petroleum. The seaward margins of the Los Angeles 
and Ventura basins received accumulations of highly 
organic siltstone during Repetto (earliest Upper Neo- 
gene, or lower Pliocene) time, while thick sandstone 
lenses and bodies were accumulating nearer shore and 
in shallower parts of the basins. Anticlines involving 
these sand lenses have produced millions of barrels of 
oil in such fields as Long Beach, Santa Fe Springs, and 
Ventura Avenue. That the Repetto formation furnished 
the source rock for the oil is, of course, not fully proved, 
but is believed by probably a large majority of the 
geologists familiar with conditions in these and similar 
oil fields. There seems to be good evidence that the 
Maricopa basin was not as deeply submerged during the 
Upper Neogene as the coastal basins, though the evi- 
dence hardly applies at present to all parts of the basin. 
Whether or not the basin was a deep one, it was partly 
enclosed, the bottom was deeply covered with silts, and 
the conditions about some of the oil fields, notably Buena 
Vista Hills and Elk Hills, have been interpreted as 
favoring a Pliocene origin for the oil. 



118 



Geologic History and Structure 



[Chap. V 



What little is known of Upper Neogene flora sug- 
gests that the climate was drier than it had been during 
the early Tertiary ; and the evidence of some of the late 
Upper Neogene faunas found in the San Pedro district 
shows that it became definitely cooler at that time than 
it had been earlier. / 

Close of Upper Neogene and Post-Tertiary Record 

During the later Neogene time the widespread basin 
areas continued to subside to depths of soine thousands 
of feet, but marine waters covered only their coastal 
margins. Mountain areas were large enough and high 
enough to keep the greater part of the loWlands filled 
above sea level and to permit the accumulation of the 
nonmarine Tulare formation and the domi^antly non- 
marine Paso Robles and Saugus formations. After this 
period came a time of strong folding, which affected not 
merely the mountainous areas but also the margins of 
the basins of deposition. This was the "mid-Pleisto- 
cene," "Coast Range," or "Pasadenan" disturbance. 

In spite of its recency the date of this disturbance 
is not easy to determine in terms of the standard 
stratigraphic section. Present-day paleontologists are 
responsible for referring it, somewhat tentatively, and 
not quite unanimously, to the middle Pleistocene. ' H. R. 
Gale's discussion (Grant, U.S. 31, pp. 61, 63, etc.) is 
fairly typical, though his conclusions are more definite 
than those of some other workers. Vertebrate paleon- 
tologists have not been able to contribute as much to the 
solution of the problem as the abundance of good 
material might lead one to expect. The difficulty comes 
from the fact that the very good localities, such as 
Rancho La Brea, McKittrick, and Carpinteria, occur 
where there is a scarcity of good stratigraphic informa- 
tion. As a matter of fact, the fossils of these localities 
occur in strata that seem to be distinctly superficial, and 
perhaps younger than any of the beds that have been 
strongly and generally folded. 0. P. Hay held (27, p. 
189, ff.) that the Rancho La Brea and upper San Pedro 
fossils are Aftonian. Later workers have doubted this 
correlation because the traces of fossils found in such 
highly folded beds as basal Tulare, Lomita beds, and 
others, seem not to be older than latest Pliocene, and 
more likely to be Pleistocene. If Hay is right, then such 
uppermost Pliocene strata as the lower San Pedro cer- 
tainly have a high percentage of living species; and the 
cool-water marine faunas known in the later formations 
of California are all Pliocene. 

The age of the late folding episode must thus be 
left uncertain, though it is not older than the end of 
the Pliocene and is very possibly younger. Its main 
phase is not as late as the end of the Pleistocene, but 
its dying phases seem to be still going on. 

In view of the fact that the exact date of the folding 
is easy to determine, even in terms of the California 
stratigraphic section, only in a comparatively few places, 
and that recent work has tended to stress the import- 
ance of pre-Pasadenan Tertiary diastrophism in the 
Coast Ranges, some workers have come to doubt if the 
"mid-Pleistocene" orogeny ever existed as a definite 
period of heightened crustal movement. Stress is laid 
on the fact that earlier movements took place and that 
in mountain areas where later Cenozoic beds are 



absent and where earlier strata are strongly folded, 
there is often some doubt that the deformation of the 
beds actually found took place after the Pliocene. This 
view is very attractive to those who like to think of 
folding and faulting as long-continuing processes, 
creating their effects by acting throughout periods com- 
parable to those in which a formation or several forma- 
tions may be deposited. Unfortunately, the conditions 
in many parts of California do not make it easy to 
decide between such workers and those who like to have 
their diastrophism episodic. As explained elsewhere 
(Reed, R. D. 36, p. 50), the writer finds evidence of 
each kind of deformation, the long-continued and the 
episodic, but is inclined to the view that the Pasadenan 
folding period belongs to the latter type; and further- 
more, to the view that many of the folds of interest 
to oil geologists owe much the greater part of their 
deformation to this period of folding. 

The Kettleman Hills anticline will serve as an excel- 
lent example. In it the Tulare formation, which nobody 
would consider older than latest Pliocene (though many 
would make at least its upper part younger), is folded 
as strongly as the formations that underlie it. The anti- 
cline simply did not exist in anything comparable to 
its present form until after Tulare time. After it was 
made, furthermore, it was worn down by streams until 
thousands of feet of rock had been removed from its 
axial part. Toward the south end it was reduced to 
a featureless plain which later became buried in allu- 
vium, and the alluvium was then arched into a new, 
though gentle fold. The northern part, the North 
Dome, was not so deeply buried in alluvium, but the 
evidence of peneplanation and later warping is, in my 
opinion, conclusive. In any case, the time that has 
elapsed since the first folding must be reckoned as a 
good many thousands of years. 

If we class latest Tulare deposits as uppermost 
Pliocene — the oldest we can possibly make them — then 
the entire period of diastrophism and the period of 
peneplanation must belong to the Pleistocene, and must 
have taken place in some such period as a million years 
unless the Pleistocene was much longer than is now 
commonly believed. The later warping and subsequent 
erosion may then be Pleistocene or post-Pleistocene. 
The more we study the facts and their possible interpre- 
tations, the more we seem forced to the conclusions first, 
that the folding movements were episodic rather than 
secular; and second, that even with the Tulare classed 
as older than most stratigraphers believe it to be, it is 
hard to find time for all the post-Tulare events that 
are definitely and conclusively indicated. 

In coming to these conclusions, we should not lose 
sight of the fact that many anticlines of the Coast 
Ranges were certainly marked out and more or less 
clearly foreshadowed by pre-Pasadenan deformation ; 
and that in the mountain areas this condition was more 
marked than in the margins of the basins. Paleogeo- 
graphic studies show clearly enough that basins of depo- 
sition became gradually smaller throughout the Ceno- 
zoic; and studies of structural evolution seem to show 
equally clearly that this result was due, in part at 
least, to a gradual migration of the folding from upland 
areas to or toward the basins of deposition. 



GEOLOGIC HISTORY AND STRUCTURE OF THE CENTRAL COAST RANGES OF CALIFORNIA 



By N. L. Taliaferro* 



OUTLINE OF REPORT 

Page 

Introduction 119 

Xew and redefined geographic names 110 

Santa Lucia Range 119 

Sierra de Salinas 121 

Gabilan Mesa 121 

Gabilan Range 121 

Castle Mountain Range 121 

Acknowledgments 121 

Basement complex 121 

Mesozoic 123 

Franciscan-Upper Jurassic 123 

Knoxville-Upper Jurassic 125 

General statement 125 

First stage, lower Franciscan 126 

Second stage, upper Franciscan 126 

Third stage, upper Franciscan and lower Knoxville 126 

Fourth stage, Knoxville 126 

The Jurassic-Cretaceous contact: Diablan orogeny 127 

Cretaceous 128 

General statement 128 

Lower Cretaceous-Shasta group 129 

Mid-Cretaceous disturbance 129 

Upper Cretaceous 130 

General statement 130 

Pacheco group 131 

Santa Lucian orogeny 131 

Asuncion group 132 

Summary of the Mesozoic 134 

Tertiary 135 

Paleocene 135 

Eocene and Oligocene 136 

Miocene 138 

Miocene volcanism 142 

Pliocene 144 

Quaternary 147 

Pleistocene 147 

Terraces 149 

Pleistocene volcanism 149 

Diastrophic history and structure 151 

San Andreas rift 159 

Explanation of geologic structure sections, Plate II 162 



INTRODUCTION 

This paper is a summary of the writer's views 
regarding the structure, diastrophic history, and certain 
phases of the stratigraphy of the central Coast Ranges. 
Presentation of evidence is reduced to a minimum and 
all references to the literature have been omitted for the 
sake of brevity. Evidence for the conclusions reached 
will be submitted in detail in future papers on various 
areas and phases of the subject. The conclusions pre- 
sented here are based on 15 years' detailed mapping in 
the Coast Ranges, assisted by approximately 20 students 
each year, on the work of graduate students of the Uni- 
versity of California in adjacent areas, and on many 
reconnaissance trips throughout the Coast Ranges. 
Studies in the Sierra Nevada and in the northern Coast 
Ranges have greatly influenced some of the conclusions. 

The area treated is roughly that part of the Coast 
Ranges between the latitude of San Francisco Bay on 
the north and Santa Barbara County on the south, 
excluding that part of the San Joaquin Valley and the 

* Professor of Geology and Chairman of Department of Geolog- 
ical Sciences, University of California, Berkeley. California. Manu- 
script submitted for publication, December 8, 1940. 



adjacent mountains south of Kettleman Hills and west 
of the Carrizo Plain, a region in which the writer luis 
clone no detailed mapping. Not every part of this large 
and often rugged area has been mapped and the present 
paper should be regarded as a progress report. How- 
ever, its presentation at this time, even though detailed 
evidence is omitted, is believed to be justified as it con- 
tains much that is new and unpublished. 

Although there are many gaps in our "knowledge of 
the details of the central Coast Ranges it is believed that 
the major features of their complex history are fairly 
well known. Practically all of the Santa Lucia Range 
and the Gabilan mesa and much of the Diablo Range 
have been mapped. The widest gaps in our knowledge 
are in the northern part of the Diablo Range and the 
southeastern part of the Santa Cruz Mountains. 

Equality of treatment of all of the chapters of the 
history of the central Coast Ranges has not been 
attempted. Since most of the writer's investigations, 
outside of the areas mapped in detail, have been con- 
nected with the Upper Jurassic and Cretaceous and 
since he believes that much of his information regarding 
these beds is new, a much fuller treatment is given these 
earlier rocks. The literature of the Tertiary of this 
region is voluminous and hence there is little necessity 
for any but the broadest treatment of the later 
sediments. 

This report is written primarily for those who are 
familiar with the geography and stratigraphy of the 
Coast Ranges. It has been impossible to prepare the 
maps that would be necessary for those unfamiliar with 
the region. Since reference is rarely made to any 
smaller unit than part of a county or quadrangle only 
two general maps have been included, one showing the 
counties and ranges and the other the quadrangles in 
and adjacent to the central Coast Ranges. Locations of 
the accompanying cross-sections are shown on these 
maps. 

NEW AND REDEFINED GEOGRAPHIC NAMES 

As certain geographic names have been used in 
senses slightly different from those usually employed 
and as one or two new names have been introduced these 
will be defined. 

Santa Lucia Range 

On the various topographic maps of the region this 
name is applied to the mountainous region extending 
from Monterey Bay to the Cuyama River. Immedi- 
ately south of the Cuyama River the name San Rafael 
Mountains is used. This is illogical as there is no break 
at this point and the same beds and structures cross the 
Cuyama River. As used here the Santa Lucia Range 
is the mountainous area between the Salinas Valley and 
the coast which extends from Monterey Bay to the cen- 
tral part of San Luis Obispo County. As thus defined 
it is not only a geographic but a structural unit. It is 
approximately 110 miles long and 15 to 30 miles wide. 



120 



Geologic History and Structure 



[Chap. V 




Fig. 56. Map o£ central Coast Ranges of California showing principal mountain ranges and the position of structure sections. 



Central Coast Range s — T aliaferro 



121 



Sierra de Salinas 

Now essentially a part of the Santa Lucia Range but 
separated from the main range in the Miocene by a 
seaway. Land-laid Miocene sediments, passing upward 
into marine beds, occur about its southern end, and 
there seems to be little doubt that it stood as an island 
in the Miocene sea. This range, which attains an eleva- 
tion of nearly 4,000 feet, extends along the west side of 
the Salinas Valley from a point a few miles south of 
Salinas almost to the" Arroj r o Seco, a distance of about 
25 miles. The King City fault bounds the east side of 
this range. 

Gabilan Mesa 

That broad and somewhat indefinite area, underlain 
by ancient crystalline rocks, extending northwestward 
from the La Panza Mountains. Its northeastern bound- 
ary is approximately the San Andreas fault ; its south- 
western boundary is very irregular and indefinite. The 
hypothetical "Nacimiento fault" was created to serve 
as the southwestern boundary but this fault exists only 
on paper and not in the field. This broad feature, 
faintly outlined in the Upper Cretaceous, was definitely 
established in the early Eocene as a great southwest- 
ward tilted block. Its northeastern side is definite but 
its downtilted southwestern side is very indefinite and 
only occasionally marked by faulting. Its southwestern 
part merges into the Santa Lucia Range. As thus 
defined it includes that part of the Santa Cruz Moun- 
tains west of the San Andreas and Pilarcitos faults. 

Gabilan Range 

That part of the Gabilan mesa, lying east of the 
northern end of the Salinas Valley, in which the ancient 
crystalline rocks are exposed at the surface. It is 
believed that it first came into existence by upwarping 
in the Upper Cretaceous; it was further uplifted and 
accentuated by faulting in the Eocene. 

Castle Mountain Range 

This is a new geographic term proposed for a definite 
structural unit usually included in the Diablo Range. 
It is a comparatively narrow feature approximately 60 
miles in length which extends northwestward from 
Orchard Peak and includes Castle Mountain, Table 
Mountain, Smith Mountain, and Mustang Ridge. It 
narrows toward the northwest and ends against the 
crystalline rocks of the Gabilan mesa. Its position and 
structure are shown on the accompanying maps and 
cross-section. 

ACKNOWLEDGMENTS 

The writer wishes to express his gratitude to the 
many former students of the University of California 
who made possible the detailed mapping of so large an 
area in the central Coast Ranges. He is especially 
indebted to Charles M. Gilbert, R. E. Turner, and C. E. 
Van Gundy, without whose assistance the work could 
not have been accomplished. Many reconnaissance trips 
have been taken with Dr. Olaf P. Jenkins and acknowl- 
edgments are due him for many discussions in the field 
and constant encouragement in the preparation of this 
report. H. G. Schenek, S. W. Muller, F. M. Anderson, 
B. L. Clark, Alex Clark, and W. T. Popenoe have kindly 
determined many of the fossils collected. A number of 
geologists and oil companies have supplied well data 



which have been of great assistance in the preparation 
of cross-sections. Financial assistance by the Board of 
Research of the University of California is gratefully 
acknowledged. 

BASEMENT COMPLEX 

The term "basement complex" is used to include the 
Sur series and the Santa Lucia granodiorite, a complex 
of crystalline rocks on which the later Jurassic, Cre- 
taceous, Tertiary, and Quaternary have been deposited. 

The Sur series includes highly metamorphosed sedi- 
mentary and volcanic rocks which have been intimately 
intruded by various types of plutonic igneous rocks 
(Santa Lucia) and extensively granitized. The sedi- 
ments have yielded quartzites, various types of mica 
schists, marble and fine-grained black quartzites derived 
from cherts; the associated flows and tuffs have been 
converted into amphibolitic schists of many types. The 
crystalline schists universally stand at high angles and 
great difficulty would be encountered in working out 
their structure. In general the stage of metamorphism 
is that of the middle and upper mesozone, merging into 
the extremes of plutonic metamorphism on deep seated 
igneous contacts. On such contacts widespread gran- 
itization is a characteristic feature. The plutonic rocks 
have a wide range of composition, varying from syenitic 
types to very basic diorites; granodiorite is probably 
the prevailing type. Pegmatites are' extensively devel- 
oped and sometimes predominate over rather large 
areas. 

At present these rocks are only exposed along and 
west of the San Andreas fault. They are typically 
developed in Santa Cruz, San Benito, Monterey, and 
San Luis Obispo Counties with minor occurrences in 
adjacent counties. The largest continuous areas are in 
the northern Santa Lucia Range, extending southeast- 
ward into the northern part of the Cape San Martin 
quadrangle and the headwaters of the Nacimiento River. 
They underlie the Gabilan mesa and a part of the La 
Panza Range. Ordinarily where they are within six 
or seven thousand feet of the surface they form a rigid 
basement which has yielded by faulting rather than 
folding. Where they lie at greater depths the overlying 
rocks have yielded by complex folding and faulting. 
Their present exposures are due to diastrophism in the 
late Cretaceous and at various times in the Tertiary. 

There is little or no definite evidence as to the age 
of these rocks. Several elaborate attempts have been 
made to correlate the bedded rocks with Sierra Nevada 
bedrock metamorphics and the granodioritic rocks with 
the late Jurassic (or early Cretaceous) plutonic 
invasions. The writer is familiar with the Sierran rocks 
and can see no reason for such a correlation, especially 
in the case of the plutonic rocks. Certain of the sedi- 
ments and volcanics might be equivalent to the lower 
part of the Sierran Paleozoic catchall, the Calaveras, but 
they might equally well be correlated with the Cole- 
brooke schists of Oregon or the Abrams and Salmon 
schists of northern California which are rather certainly 
pre-Silurian and quite possibly pre-Cambrian. Debris 
of the Sur series are present in middle Upper Jurassic 
sediments of the Sierra Nevada, which have been 
intruded and metamorphosed by the Sierran plutonics. 
From evidence afforded by pebbles in Jurassic conglom- 
erates in the Sierras these rocks appear to have reached 



122 



Geologic History and Structure 



[Chap. V 




SCALE 
10 » o n *0 30 40 90 «0 



7B»- 



Fio. 57. Map of central Coast Ranges showing location of U. S. Geological Survey topographic quadrangles 

and position of structure sections 



Central Coast Range s — T aliaferro 



123 



their present stage of metamorphism long before the 
close of the Jurassic. They are in a more advanced 
stage of metamorphism than the Upper Paleozoic rocks 
of the Sierras. 

While no definite statement may be made regarding 
their age the writer considers that all the available evi- 
dence points to their being older than the Upper Paleo- 
zoic. They may be Lower Paleozoic or pre-Cambrian or 
both. 

MESOZOIC 

FRANCISCAN-UPPER JURASSIC 

There are no sediments in the central Coast Ranges 
older than the Upper Jurassic, other than the crystalline 
schists previously mentioned. It is possible that sedi- 
ments older than the Jurassic may have been deposited 
and subsequently removed by erosion but the writer 
believes such a supposition extremely unlikely. Meta- 
morphosed Upper Jurassic sediments older than the 
Franciscan are present in the extreme northern Coast 
Ranges of California and Triassic sediments are very 
probably present south of the Transverse Ranges but 
from regional studies it is believed that the central and 
much of the northern Coast Ranges as well as a part 
of the present Pacific Ocean made up a land mass no 
part of which was submerged below sea level until the 
deposition of the Franciscan. 

The Franciscan consists of a heterogeneous, but 
rather characteristic, assemblage of shallow marine 
elastics and chemical and organic sediments of great 
thickness deposited in a sinking geosynclinal basin 
which extended the entire length of the Coast Ranges 
of California and northward into Oregon for an 
unknown distance. Widespread and extensive volcan- 
ism took place, especially in the upper part of the Fran- 
ciscan, and resulted in the outpouring of pillow basalts 
and andesites and the intrusion of sills, dikes, and lacco- 
liths of diabase and basalt, At the exposed top of the 
Franciscan along the west side of the San Joaquin Val- 
ley, from the latitude of Tracy almost to Pacheco Pass, 
there is a very considerable thickness of andesites and 
dacites with an occasional flow of pillow basalt, These 
undescribed volcanics, high in the Franciscan, are, as 
a whole, less basic than the well-known pillow basalts. 

Throughout its entire extent the Franciscan may 
be broadly divided into two parts. The lower part 
consists largely of arkosic sandstone with very thin and 
subordinate shale partings with only occasional flows 
of basalt and few radiolarian cherts. The upper part 
consists of the same type of sandstone with more numer- 
ous dark shale partings and frequent flows of basalt and 
many lenses of red and green radiolarian chert and an 
occasional foraminiferal limestone. Thin conglomerates 
occur in both divisions. The great development of cherts 
coincides with the beginning of maximum volcanism. 

During and after the deposition of the Franciscan 
there were extensive intrusions of ultrabasic and basic 
rocks (peridotite, now largely serpentinized, and gab- 
bro and diabase). These were in the form of thick 
irregular sills, dikes, irregular laccoliths, and plugs. 
These basic and ultrabasic intrusives caused local pneu- 
matolitie metamorphism and the very erratic develop- 
ment of glaucophane, actinolite and related schists. 
Such schists are not present in the vicinity of every 
intrusion ; in fact the majority of intrusions produced 



little or no effect. Furthermore, the size of the intru- 
sion has nothing to do with the extent of the schists 
formed, as small bodies often caused the formation of 
more extensive schists than large bodies; only those 
intrusives having an excess of volatiles caused meta- 
morphism. In practically all cases the schists formed 
on the roofs of sills, due to the predominant upward 
movement of the volatiles. Small plugs occasionally 
caused the development of schist from particular layers, 
usually sandstone, and schists formed in this manner 
have been followed for several hundred yards from small 
plugs ; they present the unusual appearance of thor- 
oughly schistose layers interbedded with normal unal- 
tered sediments and having the same dip and strike. 
Not all of the contact metamorphic rocks of the Fran- 
ciscan are schistose as many are massive ; the degree of 
schistosity is largely a function of the original bedding. 
Well-bedded sediments yield recrystallized rocks with 
marked schistosity and massive rocks such as massive 
sandstones and basalts yield massive recrystallized rocks. 
Cherts yield massive quartz-albite-glaucophane rocks in 
which the constituent minerals have no directional 
arrangement but the interbedded shales are definitely 
schistose, the new-formed minerals being parallel to the 
bedding. Observations in all parts of the Coast Ranges 
show that the schistosity of the pneumatolitic rocks, 
when present, is parallel to the original bedding. 
Although new-formed prismatic minerals, such as glau- 
cophane and actinolite, lie with their long axes in the 
same general plane they usually have a random arrange- 
ment in the plane. These contact schists are not formed 
in the same manner as the crystalline schists to which 
the term schist is usually applied. Since these contact 
rocks are commonly schistose the term may be applied 
to them without involving the idea of crystallization 
under shear or pressure. The recrystallization has been 
brought about by permeation of the original rocks by 
the volatile and fluid emanations from the ultrabasic 
magmas and this permeation and the formation of new 
minerals has been strongly influenced by the bedding 
planes. 

The metamorphism took place in fairly definite 
stages which may be recognized by careful microscopic 
work. Different substances were introduced at different 
times and consequently a fairly definite sequence of new- 
formed minerals may be recognized. However, suffi- 
cient work has not yet been done on the schists as a 
whole to indicate that there is a definite sequence of 
introduction of different materials which would hold 
over wide areas. The substances commonly introduced 
are Na 2 0, MgO, CaO, Ti0 2 , and A1 2 :1 ; P,0 5 and K 2 
appear to have been introduced in some cases. A 
bewildering variety of contact rocks has resulted from 
the introduction of varying proportions of these sub- 
stances into a number of different original sedimentary 
and igneous types. 

A large number of occurrences of these contact 
schists has been seen in which it has been possible to 
distinguish the original interbeds of sandstone and 
shale by the nature and particularly the texture of the 
schist produced. The planes of schistosity have the 
same attitude as the surrounding unaltered sediments. 

The transition along the bedding from unaltered 
sandstone or shale to a completely recrystallized schist 



124 



Geologic History and Structure 



[Chap. V 



may take place with startling rapidity, sometimes within 
less than 10 feet. Almost all stages of alteration of 
sandstones into schists have been seen.- 

The glaucophane, actinolite and related schists are 
not evidence of regional metamorphism due to pressure 
or differential movement but are caused by local pneu- 
matolitic metamorphism brought about by the intru- 
sion of basic and ultrabasic rocks. 

The basic and ultrabasic intrusions become thicker 
and more numerous in the upper part of the Franciscan 
and in the overlying Upper Jurassic Knoxville owing 
to the fact that they were intruded during or imme- 
diately after the deposition of these beds and that, as 
they rose, they spread laterally more readily as the 
weight of the sediments decreased. The serpentine sills 
experienced all the intricate folding of the Franciscan 
and Knoxville sediments. Great synclines and broad 
anticlines of serpentine may be recognized and traced; 
many of these have been mapped in detail. 

The great bulk of the Franciscan sediments is made 
up of arkosic sandstone of remarkable freshness. More 
than 200 thin sections of Franciscan sandstone have 
been examined and, while there are certain broad 
regional variations recognizable, there is a remarkable 
similarity in these sandstones throughout the Coast 
Ranges of California and Oregon. Ordinarily the feld- 
spar content ranges from about 30 to over 60 percent and 
is predominantly oligoclase-andesine, although more basic 
varieties are often present. Orthoclase commonly is 
present, microcline rarely present. Quartz is always 
present and not infrequently predominates. Many 
examinations of the heavy minerals have been made and 
these, like the light minerals, are characteristic of the 
breakdown of granodiorite and crystalline schists. The 
individual grains are very angular and universally fresh 
except in occasional zones of hydrothermal metamor- 
phism. A number of analyses of the sandstones have 
been made and plotted on various igneous rock diagrams 
with the result that the sandstone is shown to have the 
composition of a granodiorite. It is believed that the 
arkose sandstones were deposited in a shallow marine 
environment. 

The cherts have been adequately described by E. F. 
Davis. Their constant association with pillow basalts 
throughout the Coast Ranges as a whole indicates the 
introduction of silica by volcanism. They are chemical 
sediments and the radiolaria present are purely acci- 
dental inclusions. One of the essential factors for the 
rapid multiplication of radiolaria was created by the 
great amount of silica introduced into the sea water. 

A regional study of the Franciscan indicates that 
the clastic material was, for the most part, derived from 
the west and probably from the same general land mass 
which contributed to the formation of the Mariposa of 
the Sierras. No debris of the rock types exposed at 
present in the Sierras is found in the Franciscan con- 
glomerates. However, it must be remembered that the 
bedrock complex of the present Sierra Nevada was only 
exposed after deep denudation and that the unmeta- 
morphosed surface rocks, which probably were shales 
and sandstones much like those of the Franciscan, could 
have been removed rapidly. The amount of debris con- 
tributed to the Franciscan by the erosion of the unmeta- 
morphosed surface rocks of the rising Sierras is 



unknown at present and is a question that never may 
be solved. The evidence at hand, however, indicates 
that the deeper more metamorphosed rocks, such as 
those of the present Sierran bedrock complex, were not 
exposed during the deposition of either the Franciscan 
or Knoxville. There is, in the central and in the south- 
ern part of the northern Coast Ranges a general west- 
ward coarsening of the Franciscan sediments and this 
fact, together with the absence of types now found in 
the Sierra Nevada, indicates that the chief source lay 
to the west. Considering all the available evidence the 
writer believes that much of the Franciscan was derived 
from a high and rugged terrain, which lay to the west 
of the present coast line, under rather rigorous climatic 
conditions, probably heavy precipitation, and a cold cli- 
mate in the highlands with rather well wooded lower 
slopes, as shown by the abundance of carbonized wood 
and plant fragments in the sandstones and shales. 
Mechanical disintegration clearly predominated over 
chemical decomposition in the rugged area from which 
the Franciscan was derived. 

The Franciscan was deposited in a sinking geosyn- 
cline which formed to the west of the ancient Sierra 
Nevada, the rocks of which had already been folded 
and probably intruded by batholitic masses but which 
was only beginning to rise. 

The writer is familiar with the hypothesis of two 
or more separate basins of deposition for the Francis- 
can but careful studies have shown a complete lack of 
evidence for such an hypothesis. There is no coarsen- 
ing of sediments toward the hypothetical Mesozoic 
Salinia nor any evidence in the sediments of derivation 
from such a land mass. The La Panza Mountains may 
have been an island during the deposition of the Fran- 
ciscan but there is much evidence against the existence 
during the Upper Jurassic, of such an hypothetical land 
mass as Salinia. 

There is no foundation for the very general belief 
that the Franciscan is extensively metamorphosed. As 
has been pointed out the glaucophane and related schists 
are due to local pneumatolitic contact action and not to 
widespread dynamo-thermal metamorphism. They occur 
in small isolated areas, even smaller than indicated on 
several published maps. Aside from a few areas which 
will be mentioned later the Franciscan shows no sign 
of dynamic alteration. The erroneous belief in the 
widespread metamorphism of the Franciscan is due to 
the heterogeneous assemblage which makes up the group 
and the several periods of comparatively shallow defor- 
mation suffered by the rocks. In many places the 
Franciscan has been intruded by innumerable plugs, 
sills, dikes and irregular bodies of basic and ultrabasic 
rocks. During the several periods of folding and fault- 
ing that have taken place the sediments have been 
crushed against these more unyielding masses and an 
enormous amount of shearing and slickensiding has 
resulted giving a false impression of metamorphism. 

Along the eastern side of the Diablo range the some- 
what slaty condition of the shales interbedded with the 
sandstones is the natural result of the weight of the load 
of sediments, 25,000 feet of Cretaceous alone, deposited 
on the Franciscan. Even the Horsetown shales in this 
region are greatly hardened. Since the bedding of the 
Franciscan in this region is nearly everywhere parallel 






Central Coast Range s — T aliaferro 



125 



to that of the overlying Cretaceous and there is no sign 
of strong orogeny between the Jurassic and Cretaceous 
beds in this particular area the slaty nature of the Fran- 
ciscan shale appears to be the result of simple load meta- 
morphism and depth of burial. 

In the northern Coast Ranges there is an area of 
Franciscan which appears to have been subjected to 
weak dynamic metamorphism. Folding was strong but 
far from isoclinal and the slight and imperfect slaty 
cleavage developed is usually at an angle to the bedding. 
There is no justification for the prevailing ideas 
regarding the widespread metamorphism of the Fran- 
ciscan. 

Another widespread superstition is that there is a 
lack or great scarcity of Franciscan debris in succeed- 
ing formations older than the upper Miocene. It may 
be stated without question, based on observation and 
a number of pebble counts, that Franciscan debris is 
present in varying amounts in all succeeding sediments, 
with the possible exception of the Eocene. 

The age of the Franciscan has been a subject of 
much debate and much unintentional confusion has been 
introduced by unjustifiable correlations of the Francis- 
can with wholly unrelated formations. No discussion of 
the reported fossils and the various correlations will be 
presented here as the writer is now engaged in the 
preparation of a paper on the Franciscan as a whole. 

The age of the Mariposa slates has been well estab- 
lished as Kimmeridgian and slightly older (all reported 
Portlandian and "Tithonian" areas in the Sierras have 
been studied by the writer and many fossils have been 
collected, none of which is younger than the Kim- 
meridgian). In Oregon the Franciscan overlies the 
Galice unconformably and the Galice, both faunally and 
lithologically, is the equivalent of the Mariposa. Fur- 
thermore the Galice has been converted into slate while 
the Franciscan is unmetamorphosed. In northern Cali- 
; fornia unmetamorphosed Franciscan occurs in close 
proximity to Mariposa-Galice slates. The Franciscan 
\ is therefore younger than the Kimmeridgian. The 
i writer is convinced that the Franciscan does not extend 
I below Portlandian or at the lowest the upper Kim- 
! meridgian and that it is not a mysterious assemblage of 
i sediments of very uncertain age but may be placed 
! within comparatively narrow age limits. The writer is 
: aware of the implications contained in the above state- 
ment with reference to the speed of the late Jurassic 
; Sierran revolution but will discuss this matter more 
'■ fully in a more appropriate place. The upper limit of 
j the Franciscan will be discussed under the Knoxville. 

KNOXVILLE-UPPER JURASSIC 
I General Statement 

The term Knoxville is used here for that part of the 
old "Knoxville" or "Shasta" group, commonly referred 
to the Lower Cretaceous, which is now regarded as 
upper Upper Jurassic and which is separated from the 
overlying Shasta series by a disconformity which locally 
becomes a definite angular unconformity. 

Perhaps there are few unconformities more fre- 
quently mentioned in the literature than that between 
the Franciscan and the "Knoxville." The writer's 
early training and a study of the literature strongly 
impressed on his mind the break between and the great 



difference in lithology and alteration of these two 
groups. For 15 years he has searched diligently in the 
field and has failed to find either the unconformity or 
the supposed radical difference in character. The only 
thing which has caused the writer to disregard his early 
impressions is continued observation in the field and not 
a preconceived idea or an attempt to fit observations 
into an hypothesis. The writer's concept of the Fran- 
ciscan-Knoxville relations, which will be stated here 
briefly, is based on field observations extending through- 
out a large part of the Coast Ranges. 

The Knoxville, as here defined, and as usually 
described, consists largely of dark clay shales with 
abundant gray to black, pure to very impure limestone 
lenses, numerous thin sandstone beds and an occasional 
conglomerate. This is an adequate description of the 
great bulk of the formation but it omits several impor- 
tant elements which are present over wide areas. 

Because of its wide distribution on the eastern side 
of the northern Coast Ranges many of the conclusions 
reached are based on that area; but fossiliferous Knox- 
ville has been studied at a number of places in the cen- 
tral Coast Ranges and has contributed greatly to an 
understanding of many obscure relations. 

Pillow basalts and volcanic breccias are of wide- 
spread occurrence in the lower part of the upper Juras- 
sic Knoxville in both the northern and central Coast 
Ranges. That the sediments with which the volcanics 
are interbedded are Knoxville is proved by the presence 
of typical Knoxville fossils in beds both below and 
between the pillow basalts and breccias. In a few 
instances the pillow basalts, which are identical with 
those in the Franciscan, are associated with radiolarian 
cherts. Thus, in addition to the ordinary elastics, the 
Knoxville contains, usually in its lower part, sediments 
and volcanics which are typical of the Franciscan. 
Thin sections show that the Knoxville sandstones are 
identical in character with those of the Franciscan 
except that they often contain a somewhat greater pro- 
portion of clayey material. 

In the northern Coast Ranges there is good evidence 
that the Knoxville may be divided into two parts sepa- 
rated by a disconformity. In places there are lenses of 
conglomerate in the Knoxville that may be traced for 
a number of miles that contain debris of both the Fran- 
ciscan and the underlying lower Knoxville. .Upper 
Jurassic fossils occur in these conglomerates as well as 
in the beds both above and below. Owing to the intense 
folding and faulting of the Knoxville in the central 
Coast Ranges these two divisions have not been recog- 
nized, thus far, south of San Francisco. No names have 
been given to these divisions and it is considered suffi- 
cient to refer to them as Lower and Upper Knoxville. 
When these divisions and their faunas become better 
known appropriate formational names may be given. 
It is believed that the slight break observed reflects a 
mild orogeny to the west. Because of subsequent ero- 
sion most, if not all, of the evidence of this orogeny has 
been removed in the higher parts of the Coast Ranges. 

In the Stanley Mountain region, north of the 
Cuyama River, in the southeastern part of the Nipomo 
quadrangle a large Knoxville fauna, consisting of a 
number of genera and species of ammonites, aucellas, 
and brachiopods, has been obtained from beds which 






126 



Geologic History and Structure 



[Chap. V 



would, without question, be mapped as Franciscan. 
The Stanley Mountain assemblage consists of dark 
shales with numerous limestone lenses, typical Fran- 
ciscan sandstones, more than 1,000 feet of pillow ande- 
sites and several hundred feet of red radiolarian cherts. 
The fossils occur most abundantly in the lower part 
below the pillow andesite and cherts but a few occur in 
sediments between flows. These beds are unconform- 
ably overlain, with an angular discordance of more than 
10 degrees, by conglomerates and sandstones containing 
a very low Lower Cretaceous fauna. Thus, in this par- 
ticular locality at least, there is positive evidence that 
beds having a definite Franciscan lithology, including 
glaucophane schists, contain a typical Knoxville fauna. 
This fauna has been called "Tithonian"; if this inter- 
pretation is correct the conditions which favored the 
formation of Franciscan types continued practically to 
the close of the Jurassic in this region and we have the 
apparent anomaly of typical upper Knoxville fossils in 
a distinctive Franciscan lithology. In regions where 
there were no outpourings of spilitic volcanics at this 
time the normal fine elastics of the Knoxville were 
formed. 

In the great majority of places the line between what, 
has been called Franciscan and the Knoxville is obscured 
by the intrusion of serpentine (occasionally passing into 
a gabbro-diabase-serpentine complex) which ranges up 
to 2,500 feet and more in thickness. In the few locali- 
ties thus far observed where this sill is either thin or 
absent no line can be drawn between the Franciscan 
and the Knoxville as there are pillow basalts and vol- 
canic breccias in the lower part of fossiliferous Knox- 
ville, and dark shales and sandstones identical with those 
of the Knoxville well down in what is usually consid- 
ered to be a distinctive Franciscan assemblage. Thus, 
only an arbitrary line between the two can be drawn. 
Should the top of all the beds containing volcanic mate- 
rial be used as the line of division great confusion would 
be introduced as such a contact would be above typical 
Knoxville faunas and would, if followed for any dis- 
tance, transgress time as the volcanic rocks reach various 
horizons in the Knoxville, being much higher in some 
places than in others. Neither would it be possible to 
use the top of the great serpentine sill, referred to pre- 
viously, as it is very irregular and sometimes rises many 
thousands of feet into the Knoxville, and as there are a 
number of other large serpentine sills intrusive into the 
Knoxville far above the base. 

Although the boundary between the Franciscan and 
the Knoxville is gradational there is a marked differ- 
ence between the two when both are considered as a 
whole. The Knoxville is largely made up of shale with 
lenses of limestone and sandstone and an occasional con- 
glomerate in very different proportions than in the Fran- 
ciscan. The Franciscan is dominantly coarse elastics 
and the Knoxville dominantly fine elastics. The essen- 
tial difference between them, broadly speaking, is not a 
difference in kind of sediment but in the relative propor- 
tion of the different types. Both were deposited in shal- 
low water in the same slowly sinking geosynclinal basin 
and both were chiefly derived from the same land mass 
to the west. In a number of regions the Franciscan 
becomes increasingly shaly in its upper part and, in a 
few places where the relations may be observed, becomes 



somewhat finer grained eastward. The writer believes 
that the gradual wearing down of the source of the 
detritus making up both the Franciscan and Knoxville 
resulted in a decrease of coarse elastics and an increase 
in fine material supplied to the basin of deposition. 
Broadly speaking, the Franciscan and the Knoxville rep- 
resent a cycle of deposition in a sinking geosynclinal 
trough in which not less than 25,000 feet of sediments 
and volcanics accumulated. Slight interruptions of 
deposition took place in both the Franciscan and Knox- 
ville as shown by disconformities in both similar to that 
previously mentioned which separates the lower and 
upper Knoxville. These disconformities probably reflect 
uplifts in the source of supply and on the borders of 
the sinking basin. 

The entire sequence may be divided into four parts 
which merge into each other. There are many local 
irregularities and overlapping as well as slight breaks 
v,ithin the stages but it is believed that such a divi- 
sion, with all its imperfections and generalizations, will 
serve a useful purpose and clarify many obscure rela- 
tionships. 

First Stage, Lower Franciscan 

Arkose sandstones, representing the rapid, chiefly 
mechanical, degradation of a recently uplifted rugged 
land mass to the west, were deposited in a sinking basin 
between this western land mass and the recently folded 
ancestral Sierras to the east. That the ancestral Sierras 
had not yet attained any appreciable elevation is indi- 
cated by the absence of any recognizable detritus of 
eastern origin. Very little voleanism and few chemical 
or organic sediments. 

Second Stage, Upper Franciscan 

Beginning of widespread voleanism. Continued 
deposition of arkose sandstone but with many interdigi- 
tations of shale and occasional conglomerates, often con- 
taining Franciscan debris and representing minor 
uplifts in the source of supply and on the borders of 
the basin. Maximum development of cherts and an 
occasional foraminiferal limestone. Beginning of the 
intrusion of basic and ultrabasic rocks. 

Third Stage, Upper Franciscan and Lower Knoxville 

Continued deposition of coarse and fine elastics with 
shales becoming more abundant. Waning of voleanism 
and marked decline in chemical sediments (cherts). 
Many basic and intermediate flows but chiefly submarine 
explosions resulting in tuffs and breccias; abundant 
Knoxville fauna. The third stage is, as a rule, much 
thinner than the others. 

Fourth Stage, Knoxville 

Chiefly fine elastics, silts, sandy shales, sandstones, 
and an occasional conglomerate. Cessation of voleanism 
and deposition of chemical sediments except in local 
areas. Continued intrusion of large bodies of ultrabasic 
and basic rocks which lasted almost to the close of depo- 
sition. Abundant Knoxville fauna. 

Because of many local variations, such as character 
of the coast line, elevation of the source of supply, 
drainage courses, centers of voleanism and slight dif- 
ferences in time of beginning and ending of voleanism in 
different regions, these divisions cannot be used as defi- 
nite formations or cartographic units except in local 
areas. However, it is believed that they give an ade- 






Central Coast Range s — T aliaferro 



127 



quate and comprehensive picture of the usual sequence 
of events in the Coast Ranges during: the closing stages 
of the Jurassic, in all probability during the Upper 
Portlandian and "Tithonian" (Aquilonian). 

The Knoxville is made up of the same general litho- 
logic types in approximately the same proportions 
throughout the central and northern Coast Ranges, indi- 
cating rather uniform conditions during its deposition. 
There is nothing in the character or lithology of the 
Knoxville to indicate deposition in separate basins of 
deposition. It does not cover large areas in the central 
Coast Ranges but it is present in a number of widely 
scattered localities, from the western side of the San 
Joaquin Valley almost to the Pacific Ocean, including 
areas within and on the margin of the hypothetical 
land mass of "Salinia" and throughout this entire 
region its character and fauna are the same. There is 
no evidence that "Salinia" had come into existence in 
the Upper Jurassic. In fact, there is rather definite 
evidence against this hypothetical land mass until a much 
later date. 

Considering all the available evidence, which has 
been briefly sketched above, it is believed that both the 
Franciscan and the Knoxville were deposited in the 
same general geosynelinal basin and that this basin 
extended throughout the central and northern Coast 
Ranges of California and northward into Oregon. This 
geosyncline lay between a great land mass to the west 
and the slowly rising Sierran mass to the east. The 
drainage was chiefly from the west and the bulk of the 
sediments apparently were derived from that direction. 
Disturbances occurred in the land mass to the west and 
on the border of the basin resulting in slight discon- 
formities within both the Franciscan and the Knoxville 
but no recognizable break occurs between them. Islands 
or peninsulas may have existed in this sinking basin, 
especially in the vicinity of the present La Panza Moun- 
tains but there is no evidence to support the hypothesis 
of separate basins of deposition. 

The presence of intrusive bodies of serpentine in the 
Knoxville was first mentioned many years ago but there 
are still a few who vigorously deny that such intrusive 
bodies exist and various hypothetical explanations are 
offered. Such explanations consist in calling' the Knox- 
ville sediments, when intruded by serpentine, "Francis- 
can," or the serpentines, "cold intrusions." Such state- 
ments have served only to confuse an already complex 
problem. The writer has mapped several cold intru- 
sions of serpentine in beds as high as the Miocene but 
these have no similarity to the great sills and irregular 
bodies intrusive into Franciscan and Knoxville beds. In 
a future paper on the Franciscan and Knoxville the 
writer will present detailed evidence regarding this mat- 
ter. It is sufficient here to point out the presence of 
Knoxville fossils below, between, and above folded sills 
of serpentine, the very irregular sinuous baked contacts 
and the presence of glaucophane schists clearly derived 
from fossiliferous Knoxville beds. Such schists have 
been found in five widely separated localities in the 
northern and central Coast Ranges, including the type 
section of the Knoxville. The usual lack of development 
of glaucophane and related schists on the margins of 
even large serpentine bodies intruded into the Knox- 
ville is believed to be the result of a loss of volatiles and 



iheir utilization as serpentinizing agents during the rise 
of the ultrabasic magmas high into the thick prism of 
sediments that had accumulated in the geosyncline. 

THE JURASSIC-CRETACEOUS CONTACT: 
DIABLAN OROGENY 

The Jurassic was brought to a close by widespread 
uplift which affected, in varying degrees of intensity, 
the entire region of the present Coast Ranges. Along 
the west side of the Great Valley the emergence was 
slight but to the west in the central Coast Ranges there 
are strong overlaps. This disconformity, which locally 
becomes a distinct unconformity, has been observed in 
many places in both the northern and central Coast 
Ranges. Usually the base of the Lower Cretaceous is 
marked by a basal conglomerate containing debris of the 
Franciscan and Knoxville, as well as a great variety of 
older rocks. Granitic debris is only conspicuous in 
northern California but pebbles of the ubiquitous 
ancient porphyries so common in most of the conglom- 
erates of Coast Ranges, are abundant. The basal con- 
glomerate is, in some localities, as much as 500 feet in 
thickness but it is usually much thinner and not uncom- 
monly grades laterally into sandstone or even shale. 

In northern California the basal Lower Cretaceous 
gradually overlaps northward both Knoxville and Fran- 
ciscan and finally rests on Paleozoic rocks in Tehama 
County. Because of faulting, there are few normal 
relations between the Upper Jurassic and Lower Cre- 
taceous along the west side of the San Joaquin Valley 
but to the west, in the Diablo Range, there are a number 
of widely scattered localities in which interesting and 
important relationships may be seen. In the southeast- 
ern part of San Benito County, about in the center of 
the Diablo Range, fossiliferous Lower Cretaceous ( Pas- 
ken ta) sediments rest on typical Franciscan rocks, both 
igneous and sedimentary, without any intervening 
Knoxville. However the basal Paskenta conglomerate 
contains abundant debris of the Knoxville, much of it 
little rounded, indicating that Knoxville sediments had 
been present in this region. To the southwest, east of 
Priest and Waltham Valleys, fossiliferous basal Lower 
Cretaceous conglomerate rests, without angular discord- 
ance, on fossiliferous Knoxville shales, limestones and 
sandstones. In this region the basal Cretaceous con- 
glomerate usually is thin but in several localities, which 
appear to have been low headlands extending into the 
encroaching Lower Cretaceous sea, there are conglom- 
erates, or rather breccias, containing blocks of Knoxville 
sediments and diabase and gabbro intrusive into the 
Knoxville, up to 5 feet in diameter. Both the Upper 
Jurassic Knoxville and the Lower Cretaceous Paskenta 
sediments are vertical in this region and there is no 
noticeable angular discordance. Both are abundantly 
fossiliferous; the fauna in the conglomerate indicates 
that it represents a very low stage in the Lower Cre- 
taceous. 

To the southwest in the Santa Lucia Range, in 
northern San Luis Obispo County, the Knoxville and 
Lower Cretaceous, both greatly folded and faulted, lie 
in a syncline along the crest and west side of the range. 
On the western side of the syncline basal Lower Cre- 
taceous conglomerates rest on Knoxville shales and on 
the eastern side on typical Franciscan cherts, sand- 



128 



Geologic History and Structure 



[Chap. V 



stones, and basic and ultrabasic intrusives. Thus there 
is evidence of uplift, resulting in erosion of the Knox- 
ville, in both the Diablo and Santa Lucia Ranges at the 
close of the Jurassic. 

No intrusions of basic and ultrabasic rocks have 
been found in the Lower Cretaceous above the Upper 
Jurassic-Lower Cretaceous interval nor are there any 
contemporaneous flows of pillow lavas such as those in 
the lower part of the Knoxville. In fact the basal 
Lower Cretaceous conglomerates contain rather abun- 
dant debris of these intrusive and extrusive rocks so com- 
mon in the Franciscan and Knoxville. 

The conclusions reached regarding the nature of the 
diastrophism which occurred at the close of the Jurassic 
are necessarily based on relatively small, widely scat- 
tered localities. Many periods of diastrophism have 
occurred in the central Coast Ranges since the deposi- 
tion of the Lower Cretaceous and much of the evidence 
has been removed by erosion or by burial beneath 
younger beds. However since all of the evidence that 
has been gathered is consistent and points in the same 
general direction it is believed that the conclusions are 
reasonable. 

In the very late Upper Jurassic the entire Coast 
Ranges were uplifted and locally warped. No strongly 
folded mountains were formed, but parts of the Diablo 
and Santa Lucia Ranges were brought above sea level 
and eroded. The basins between these warps were only 
slightly disturbed and probably rose but little above sea 
level. The upwarping in the Diablo Range may have 
been in part accomplished by the intrusion of thick sills 
of ultrabasic rock but the extent to which these thick 
intrusions caused uplift is difficult to estimate. It is 
believed that the greater part of the uplift was caused 
by compressive stresses but the possibility of local uplift 
by intrusion can not be ignored. 

The uplift and broad warping at the end of the 
Jurassic were more severe and widespread than any of 
the disturbances during the deposition of the Franciscan 
and Knoxville. However the geosyncline in which the 
late Upper Jurassic beds were deposited was not 
obliterated or even fragmented by the very late Upper 
Jurassic diastrophism, and widespread deposition and 
down-sinking continued through the Lower Cretaceous. 
The Lower Cretaceous sediments are practically identi- 
cal, lithologically, with those deposited in upper Knox- 
ville time. The major axis of the geosyncline may have 
been shifted slightly eastward but the evidence is by 
no means conclusive. 

The diastrophism which closed the Jurassic must 
have occupied a comparatively short interval of time 
since the upper Knoxville contains a very late Upper 
Jurassic fauna and the basal Lower Cretaceous con- 
glomerate represents a very low stage in the Lower 
Cretaceous. 

The diastrophism which closed the Jurassic was 
much stronger and more widespread than has beeu 
recognized heretofore. It was especially severe in the 
Diablo Range and for this reason the writer proposes 
the name Diablan for this orogenic event. 

CRETACEOUS 
General Statement 

Cretaceous sediments of great thickness and prob- 
ably representing all known stages from the lowest to 



the highest were deposited over a very large part of 
the Coast Ranges and, in the Upper Cretaceous, on the 
flanks of the Sierra Nevada. More than 50,000 feet of 
Cretaceous sediments accumulated but because of shift- 
ing basins of deposition and unconformities the maxi- 
mum thickness of any one section rarely exceeds 30,000 
feet. 

These sediments were deposited in very shallow water 
in sinking basins. The greatest accumulation in both 
the northern and central Coast Ranges took place in a 
long, probably continuous but far from uniform trough 
which lay along the western border of the Great Valley. 
Great floods of detritus from an eastern source first 
appeared during the deposition of this thick prism of 
shallow-water sediments. The time of the first appear- 
ance of large quantities of Sierran detritus is not known 
with certainty but it seems to have been in the Upper 
Cretaceous. 

The Cretaceous as a whole consists of thick monoto- 
nous sequences of arkose sandstones, conglomerates, 
sandy shales and thin impure limestones ; organic shales 
are abundant only in one formation, the Moreno, high 
in the Upper Cretaceous. Although there are many 
local variations the lower part consists predominantly 
of shale and the upper part of sandstone and sandy 
shale. Contemporaneous volcanism was practically non- 
existent during the accumulation of this thickness of 
elastics but very minor and unimportant submarine 
explosions occurred locally in the lower part of the 
Lower Cretaceous and the upper part of the Upper 
Cretaceous. As previously reported by the writer there 
are thin bentonite beds and impure cherts in the Moreno 
formation in Hospital Canyon in southwestern San 
Joaquin County and ash beds in the Lower Cretaceous 
(Paskenta) southwest of Parkfield and to the south of 
Orchard Peak in western Kings County. As far as is 
known these thin beds constitute the only record of 
contemporaneous submarine volcanism during the Cre- 
taceous. 

A well-known and very troublesome characteristic 
of the Cretaceous, particularly of the Upper Cretaceous, 
is the rapid lateral variation in lithology. This feature, 
together with a frequent lack or scarcity of fossils, causes 
difficulty in separating the sediments into cartographic 
units that may be followed for any distance. 

A broad and comprehensive treatment of the Cre- 
taceous as a whole and its division into units, based on 
physical discontinuities and characterized by distinct 
faunas, is difficult because there is so little known regard- 
ing the faunas and their correlation. The Cretaceous 
is abundantly fossiliferous in some localities but there 
are great thicknesses and large areas which have yielded 
faunas so scanty as to be of little value. So many 
formational, group, and series names have been used, 
often with a bewildering variety of meanings that the 
task of reconciling them seems almost hopeless. From 
a regional study of the Cretaceous in both the northern 
and central Coast Ranges it is clear that the Cretaceous 
is, throughout the Coast Ranges, divisible into two units 
separated by a major physical break. In parts of the 
central Coast Ranges there is definite evidence of two 
major physical breaks but, chiefly because of a lack of 
positive information in several areas, these breaks in 
sedimentation have not been recognized everywhere in 



Central Coast Range s — T aliaferro 



129 



the region. Evidence obtained in the Santa Lucia 
Range, in parts of the Diablo Range and on the west side 
of the San Joaquin Valley indicates that a three-fold 
division may be made, based on definite physical dis- 
turbances. In the Santa Lucia Range these disturb- 
ances were strong and resulted in folding and faulting 
and in angular discordance of as much as 80 degrees ; 
the disturbances decreased in magnitude eastward 
toward the center of the basin of deposition where they 
are represented by disconformities only. Unquestion- 
ably there were more than two periods of disturbance 
during the Cretaceous but, from the evidence obtained 
thus far, most of these were local. The two major 
diastrophisms, resulting in the three-fold division, seem 
to have been general and to have affected at least a large 
part of the central Coast Ranges, and probably the 
Coast Ranges as a whole, but in varying degree. How- 
ever since the evidence is not clear in all localities, chiefly 
because of a lack of definite information, this proposed 
division may be regarded as chiefly for the purpose of 
presenting a somewhat simplified account of the many 
events which resulted in the accumulation of such a 
great volume of sediments. 

During the Cretaceous the extensive Upper Jurassic 
geosyncline, in which were deposited the Franciscan 
and Knoxville, became restricted and finally separated 
into smaller basins of deposition. Also during the Cre- 
taceous the ancient Sierras were deeply eroded and con- 
tributed large volumes of sediment to the Upper Cre- 
taceous basins. 

The three proposed divisions and the diastrophic 
events separating them will be discussed and a brief 
statement made regarding their character and extent. 

Lower Cretaceous-Shasta Group 

The lowest division of the Cretaceous, the Shasta 
group, is thickest and best developed in northern Cali- 
fornia where it lies in a long north-south belt west of 
the Sacramento Valley and in small areas as far west 
as the Pacific Ocean. In the central Coast Ranges it is 
found in many widely scattered localities from the San 
Joaquin Valley to within less than 3 miles of the Pacific 
Ocean and from the Berkeley Hills to Santa Barbara 
County. The writer has collected Shasta fossils in the 
Santa Cruz Mountains and in the Diablo, Santa Lucia, 
Mount Hamilton and San Rafael Ranges. The distri- 
bution of the Shasta in the central Coast Ranges coin- 
cides with the distribution of both the Franciscan and 
the Knoxville and, notwithstanding the disconformity 
(locally an unconformity) at the base of the Shasta, 
it seems to have been deposited in essentially the same 
geosynclinal trough as the Franciscan and Knoxville 
and to have had the same wide distribution. Additional 
evidence for its continuous deposition over a wide area 
is its rather uniform lithologic character and the nature 
of its fauna in all of the widely scattered localities in 
which it is found in the central Coast Ranges. The 
hypothetical land mass of Salinia had not yet come 
into existence as there are thick Lower Cretaceous sec- 
tions over the northwestern part of the area supposed to 
lie within this land mass and even thicker sections of 
shales along its eastern border and even on its eastern 
edge. 

The Shasta group in the northern Coast Ranges has 
a maximum thickness of over 20,000 feet. Because of 



folding and faulting in the central Coast Ranges its 
maximum thickness is not known but in some localities 
it is more than 5,000 feet thick. 

The Shasta group consists chiefly of shale but there 
are frequent interdigitations of sandstone and impure 
limestone ; conglomerates are present at the base and 
occasionally in higher parts of the section. Lithologi- 
cally it is practically identical with the sediments of the 
upper part of the Knoxville but faunally the two are 
distinct. No basic or ultrabasic rocks, similar to those 
in the Franciscan and Knoxville have been found in- 
truding the Shasta. In fact the basal Shasta conglom- 
erate contains, in some localities, fairly abundant debris 
of these igneous rocks. 

In northern California the Shasta has been divided 
into two units, the Paskenta (lower Shasta) and the 
Horsetown (upper Shasta), each said to be characterized 
by distinct faunas. Lithologically the two are similar 
if not identical, the contact is gradational, and it is very 
difficult to draw a satisfactory contact between them in 
the field. Until the faunas have been more thoroughly 
studied and described and the relations between them 
more fully understood, it seems more appropriate to 
consider them as faunal stages rather than distinct 
formations. With our present limited knowledge of 
these sediments there is no justification in giving either 
the Paskenta or Horsetown the status of a group. 

The Lower Cretaceous (Shasta group) of the central 
Coast Ranges is chiefly represented by the Paskenta 
stage, although Horsetown fossils have been found in 
a few places, especially on the east side of the Diablo 
Range. No definite conclusion may be reached at 
present regarding the absence of known Horsetown 
over large parts of the central Coast Ranges, but the 
writer is inclined to the belief that it is due to subse- 
quent erosion rather than to nondeposition. 

The Shasta has been stated to be the equivalent of 
the Infravalanginian, Valanginian, Hauterivian, Barre- 
mian, Aptian, and a part of the Albian and therefore to 
represent practically all of Lower Cretaceous time. 
(There is no general agreement among various authors 
as to the exact limits of Lower Cretaceous in terms of 
the European section.) The writer has no reason to 
question the validity of this correlation but he simply 
wishes to point out that if this is true very little time 
is allowed for the marked diastrophic events which 
ended the Shasta, as the succeeding "Chico series" is 
supposed to extend continuously from the upper part 
of the Albian through the Cenomanian and Turonian. 
The extensive and important diastrophism which ended 
the Shasta and caused many important changes in basins 
of deposition therefore would be limited to a small 
fraction of the Albian. This appears to be another 
example of the relative rapidity of diastrophism as 
compared with deposition. 

Mid -Cretaceous Disturbance 

Although there may be some uncertainty as to the 
exact time, with reference to the European section, at 
which the events that ended the Shasta deposition took 
place there can be no uncertainty regarding the fact 
that such an event actually occurred or that it was 
of importance and affected the Coast Ranges as a whole. 
Everywhere there is either a definite disconformity or 
a strong unconformity or overlap between the Shasta 



130 



Geologic History and Structure 



[Chap. V 



: 



and the next succeeding Cretaceous sediments. In some 
localities in the central Coast Ranges, especially in the 
Santa Lucia Range, there is evidence of deep erosion 
and profound overlaps. In many places a distinct 
change in type of sediments naturally resulted and we 
find a slight general coarsening of the sediments brought 
about by uplift on the borders of and within the Lower 
Cretaceous geosyncline. Thus this disturbance not only 
affected the borders but also resulted in fragmentation 
of the formerly extensive Lower Cretaceous geosyncline. 
As in the case of the Diablan orogeny the mid- 
Cretaceous disturbance was strongest in the Santa Lucia 
and Diablo Ranges which were uplifted and partially 
stripped of their Upper Jurassic and Lower Cretaceous 
cover. Certain parts of the Lower Cretaceous basin 
appear to have been little disturbed, as for example 
along the eastern side of the Diablo Range, in San 
Joaquin, Stanislaus, and Merced Counties, where lower 
Upper Cretaceous beds rest disconformably on the Horse- 
town stage of the Lower Cretaceous. A part of the 
present Gabilan Range appears to have risen and been 
extensively stripped at this time. Evidence for this is 
the character of the Upper Cretaceous beds northeast 
of Waltham Creek and Priest Valley where heavy Upper 
Cretaceous conglomerates rest unconformably on Lower 
Cretaceous shales. These heavy conglomerates rapidly 
thin and become finer grained eastward. The cobbles 
and boulders are largely made up of basement complex 
rocks. Thus a part of "Salinia" emerged at this time 
but the part that was emergent was only a fraction of 
the hypothetical "Salinia" as the northwestern part was 
submerged as shown by thick sections of Upper Creta- 
ceous sediments. 



Upper Cretaceous 



General Statement 



The Upper Cretaceous is divisible into two parts sepa- 
rated by a strong orogenic disturbance. Owing to the 
lack of satisfactory faunas in many places it is not 
always possible to distinguish between these divisions 
everywhere and, consequently, it is not always possible 
to separate the effects of the mid-Cretaceous disturbance 
from that which occurred in the Upper Cretaceous, 
probably between the Turonian and the Coniacian. 
However, there is sufficient evidence to show that there 
are two well-defined divisions in the Upper Cretaceous 
separated by an orogenic period and that the uppermost 
Cretaceous division is more widely distributed in the 
central Coast Ranges than the lower. 

Although there is much that is yet unknown regard- 
ing the distribution and faunas of these two divisions of 
the Upper Cretaceous, enough is now known to enable 
us to obtain a reasonable picture of their general dis- 
tribution. It is believed that a recognition of these two 
divisions and the events which separated them will be 
of great value in an interpretation of the complex his- 
tory of the Coast Ranges. Since they have widely dif- 
ferent distributions and since they are separated by an 
important disturbance each should be distinguished by 
a definite name. The writer dislikes to add a new group 
name to an already overburdened literature but when 
the present confused state of the nomenclature of 'the 
Upper Cretaceous and the variety of ways in which 
many of the names have been used is considered it is 



believed that the introduction of new terms will serve 
a useful purpose. 

The writer does not intend to trace the history of 
the nomenclature of the Upper Cretaceous but he wishes 
to point out certain objections to the current terms. 
For many years the Upper Cretaceous was known prac- 
tically everywhere in the Coast Ranges as the Chico 
although it was frequently recognized that the various 
occurrences were not always equivalent to the Chico 
Creek section in Butte County. In many case the sym- 
bol Kc on a geologic map included not only what was 
then recognized as Chico, but Lower Cretaceous as well. 
In 1915 the term Panoche was introduced for the Cre- 
taceous along the west side of the San Joaquin Valley 
north of Coalinga. Later work has shown that the 
Panoche, as mapped at that time, includes Knoxville, 
Paskenta, and Horsetown, and extends across several 
disconformities. Recently the term Chico series has 
been used to include all the Upper Cretaceous and the 
Panoche as the upper group of this series. This usage 
is unfortunate, as it makes the Chico include beds 
separated by a disconformity which locally becomes 
a pronounced unconformity. Much as the writer would 
like to continue the use of the old term "Chico" he feels 
that its use would only be a source of confusion because 
of the variety of ways in which it has been used. 

The writer is greatly indebted to Dr. Willis P. Pope- 
noe for valuable information regarding the faunas of 
the Upper Cretaceous and wishes to quote from a letter 
from Dr. Popenoe, dated February 17, 1940. 

"To sum up, the evidence on hand suggests that there are 
probably four and possibly more distinct major faunal divisions in 
the California Upper Cretaceous, considering the bulk aspects of 
the complete faunas. It is not yet possible to say if these faunal 
divisions may be grouped into two larger assemblages corresponding 
to your middle and upper Cretaceous divisions, but it may be con- 
sidered likely, in view of the profound unconformities you find in 
the Santa Lucia range. In regard to the use of Chico as the name 
for your middle division, your doubts are similar to my own. I had 
also considered using the term as a stage name, but feel as you do 
that it has been applied in so many different senses that it would 
be well to avoid using it if it is practicable to do so. Accor,.'*"? 
to my present idea, your middle division in the Coast Ranges 
probably includes beds considerably older than any found at Chico 
Creek, and probably also considerably different faunally. A suitable 
name for your middle division might be taken from the Santa Ana 
Mountains region or from Redding, but one selected from the cen- 
tral Coast Ranges in which you have been working would under 
the circumstances probably be more appropriate." 

Because of the reasons mentioned above the writer 
believes it desirable to propose new group terms for the 
divisions of the Upper Cretaceous and a name for the 
orogenic event separating them. The proposed divisions 
of the Cretaceous are as follows: 



Upper Cretaceous 


Asuncion group 


Santa Lucian orogeny 


Pacheco group 


Mid-Cretaceous disturbance 


Lower Cretaceous 


Shasta group 


Diablan orogeny 


Upper Jurassic 


Franciscan and Knoxville 



Central Coast Range s — T aliaferro 



131 



Pacheco Group 

The name Paeheco is suggested for the lower divi- 
sion of the Upper Cretaceous because of the develop- 
ment of these beds on the Pacheco Pass quadrangle, 
especially on Quinto and Garzas Creeks where they are 
separated from the underlying Horsetown stage of the 
Lower Cretaceous and the overlying Asuncion group by 
disconformities. In this region the Pacheco consists of 
7,000 to 8,000 feet of gray sandy shales, sandstones, and 
conglomerates which are either vertical or dip eastward 
at high angles. These beds are not confined to the 
Pacheco Pass quadrangle but extend both to the north 
and south as a continuous belt. They also occur to the 
west of this belt on El Puerto Creek in western Stanis- 
laus County in a down- faulted syncline. 

The Pacheco group is less widely distributed in the 
central Coast Ranges than the Asuncion group but the 
reverse may be the case in the northern Coast Ranges. 
Beds equivalent to the Pacheco occur in the Santa Lucia 
Range, in the central part of the Adelaida quadrangle, 
where they are overlain with an angular unconformity 
of as much as 80 degrees by beds equivalent to the 
Asuncion. In the southern part of the Diablo Range, 
Pacheco beds containing Cenomanian fossils rest directly 
on the Franciscan southwest of Hernandez, but to the 
north they rest on Paskenta sediments. To the south, 
east of Priest Valley and Waltham Creek, thick Pacheco 
conglomerates, grading upward into sandstones and 
shales, rest unconformably on Paskenta, Knoxville, and 
Franciscan in turn. No unconformity between the 
Pacheco and Asuncion has been discovered in this local- 
ity, but one probably exists, as in the eastern part of 
the Priest Valley quadrangle, in the heart of the 
Coalinga anticline, Asuncion sediments rest directly on 
Franciscan sediments and serpentine. Thus the Pacheco 
sediments which lie on the west flank of the White Creek 
syncline, east of Priest Valley and Waltham Creek, do 
not reappear on the east flank of this syncline, which 
locally forms the west flank of the Coalinga anticline. 

In San Luis Obispo County, in the Nipomo and 
Branch Mountain quadrangles, both divisions of the 
Upper Cretaceous are represented but thus far the rela- 
tions between them have not been determined. 

In the Orchard Peak quadrangle the meager faunas 
that have been obtained indicate that the Pacheco is 
absent and that the Asuncion lies unconformably on 
the Shasta. To the northwest Pacheco sediments make 
their appearance. 

In the southern part of the Santa Lucia Range beds 
thought to be equivalent to the Pacheco are widely dis- 
tributed in comparatively small individual areas and are 
always unconformably overlain by the Asuncion group; 
the angular unconformity is as much as 80 degrees. 
Even where the angidar unconformity is not great the 
Pacheco sediments are overlapped by the Asuncion 
sediments which have a much wider distribution. In 
the Santa Lucia Range the Pacheco sediments are simi- 
lar lithologically to those along the west side of the San 
Joaquin Valley ; they consist of gray and black clay 
shales, often with lenses of shaly limestone, sandstones, 
and conglomerate, but the average thickness in the vari- 
ous individual areas is less than 1,000 feet. The maxi- 
mum original thickness in this region is unknown as the 
beds were deeply eroded during the Santa Lucian orogeny. 



The great bulk of the Pacheco sediments along the 
west side of the San Joaquin Valley and in the Santa 
Lucia Range are silty in nature and indicate derivation 
from ' a comparatively low land mass. The only very 
coarse Pacheco sediments occur east of Priest Valley and 
Waltham Canyon, indicating that the Gabilan mesa may 
have been above sea level at this time. Shales predom- 
inate but there are thick lenses of sandstone and con- 
glomerate. Most of the conglomerates in the Pacheco 
of the Santa Lucia Range are somewhat unusual as they 
consist of small well-rounded and highly polished 
pebbles in a silt matrix. The polish, which is unusually 
high, is like that ordinarily ascribed to wind action. 
However the writer regards the polish as the result of 
abrasion by fine silts on broad tidal flats where the mate- 
rials were constantly shifted by the tides. In the Santa 
Lucia Range the maximum exposed thickness of the 
Pacheco is about 4,000 feet. 

Pacheco beds are not known to occur in the northern 
part of the Santa Lucia Range or in the western part 
of the Santa Cruz Mountains but it is possible that 
additional work may show them to be present. 

The exact limits of the Pacheco group, in terms of the 
European divisions are not known with certainty but it 
is thought to be equivalent to the Upper Albian, the 
Cenomanian and the Turonian. According to Mr. Allen 
P. Bennison, Turonian fossils occur in boulders in con- 
glomerates on Quinto Creek which the writer regards 
as basal Asuncion. 

With our present limited knowledge it is impossible 
to make any very positive statement regarding the basins 
in which the Pacheco was deposited because so much of 
the evidence has been removed by erosion, even more 
than in the case of the Upper Jurassic and Lower Creta- 
ceous. It is certain that a long and probably continu- 
ous basin existed along the east side of the Diablo Range 
and the west side of the San Joaquin Valley. Neither 
the eastern nor western limits of this basin are known 
but it probably covered much of the present Diablo 
Range. The ancestral Coalinga anticline stood either as 
an island in or a peninsula extending northwestward 
into this basin; other islands or peninsulas may have 
existed but of this there is no present evidence. This 
same basin continued, probably without interruption, 
into the region on the east flank of the northern Coast 
Ranges and the west side of the Sacramento Valley. 
Another basin, probably separated from the long trough 
just mentioned, extends through northern Santa Bar- 
bara, San Luis Obispo, and Monterey Counties. These 
may have been separated by the present Gabilan Range 
which rose for the first time at the close of Shasta 
deposition. 

Santa Lucian Orogeny 

For the period of folding, uplift, and erosion between 
the Pacheco and Asuncion groups the writer proposes 
the name Santa Lucian because of the exposures of the 
unconformity and the wide overlaps in the Santa Lucia 
Range. It is not always possible to distinguish between 
the effects of this orogeny and the mid-Cretaceous dis- 
turbance, especially in regions where the Asuncion only 
is present. It is known that there was strong folding, 
uplift, and erosion between the Pacheco and the Asun- 
cion but where the Asuncion overlaps onto older rocks, 
as is frequently the case, it is difficult, if not impossible, 



132 



Geologic History and Structure 



[Chap. V 



to determine which disturbance caused the uplift. Con- 
sidering the marked unconformity between the two in 
the southern Santa Lucia Range it is thought that much 
of the disturbance came in the Upper Cretaceous, after 
the Pacheco. 

The Santa Lucian orogeny was strongest in the Santa 
Lucia Range and died out eastward until, on the west 
side of the San Joaquin Valley, there is no angular dis- 
cordance between the two Upper Cretaceous divisions 
north of Panoche Creek. However, that there was 
uplift and erosion is shown by the presence of fossilifer- 
ous Pacheco boulders in the basal conglomerate of the 
Asuncion. 

As a result of this orogeny the Gabilan mesa rose for 
the first time but whether by definite faulting or gentle 
up warping is not known. The northern part of the 
Santa Lucia Range was so strongly uplifted that the 
Lower Cretaceous and Upper Jurassic beds were 
stripped off completely in many places and Asuncion 
sediments frequently rest directly on the basement 
complex. 

Asuncion Group 

The name is taken from the Asuncion Grant in the 
southeastern part of the Adelaida quadrangle where 
there are good exposures of these Upper Cretaceous sedi- 
ments, resting uneonformably on both Franciscan and 
Pacheco. Fossils occur in sandstones along the road 
east of Asuncion school and in Dover Canyon but they 
are not as abundant as in other parts of the southern 
Santa Lucia Range. Thicker and more complete sec- 
tions occur in many other places, especially in the vicin- 
ity of Bryson and on the Naeimiento River. Either of 
these would be more appropriate names, but both are 
preempted. The Asuncion group consists of over 10,000 
feet of coarse conglomerates, sandstones, and shales 
which, in the Santa Lucia Range, overlie Pacheco sedi- 
ments with strong unconformity and overlap onto all 
of the older rocks, Shasta, Knoxville, Franciscan and 
basement complex. It contains a late Cretaceous fauna 
equivalent to that found in the restricted Panoche, 
Moreno, and Garzas on the west side of the San Joaquin 
Valley. In the central Coast Ranges it attains a far 
wider distribution than either the Shasta or Pacheco 
groups; the majority of the beds previously mapped in 
this region as "Chico" belong to this group. In the 
southern Santa Lucia Range it has been divided into 
the Cantinas sandstones, the Godfrey shales and the 
Piedras Altas formation. 

The name Asuncion group is used to include all of 
the upper Upper Cretaceous beds in the central Coast 
Ranges above the Pacheco. At present it is not possible 
to give the exact distribution of these two Upper Creta- 
ceous groups everywhere or to delineate the exact loca- 
tion of the basins in which they were deposited but it 
is possible to separate them over a fairly large part of 
the central Coast Ranges. The physical, and easily 
observable, fact of the pronounced unconformity 
between them in many places and the difference in their 
geographic distribution is sufficient justification for 
their separation. The names here proposed are tenta- 
tive; other names might be equally suitable and if it is 
found that any of the older names can be redefined and 
used without confusion they should be adopted. The 
two new group names are proposed for convenience of 



discussion and for the purpose of emphasizing a very 
important diastrophic episode in the history of the Coast- 
Ranges. Any names proposed in the future must take 
cognizance of this important event. 

The name "Panoche formation" was first used in 
19Lj as the. lower division of the "Chico group" and 
the type section given as the Panoche Hills in western 
Fresno County. As originally mapped and defined the 
Panoche formation includes not only a part of the pres- 
ent Asuncion group and all of the Pacheco group but 
also Shasta and Knoxville. Hence it is believed that 
its use as a group name would only, lead to confusion. 
The Panoche formation should be used for the sedi- 
ments, chiefly sandstones, above the Pacheco and below 
the Moreno. 

On the west side of the San Joaquin Valley, from 
Coalinga to the Mount Diablo region, the Asuncion 
group can be divided into three, and possibly four, 
formations. The lower two-thirds or more, the restricted 
Panoche formation, consists of conglomerates and 
arkosic sandstones with thin intercalations of sandy and 
carbonaceous clay shale grading up into the organic 
shales of the Moreno which in turn grade upward into 
the sands and silts of the Garzas. Although there 
appear to have been local interruptions in sedimenta- 
tion, especially within the Moreno, the contacts are 
gradational and the group as a whole seems to have 
been the result of continuous, or almost continuous, 
sedimentation. Future work may show the advisability 
of creating a still higher group in the Upper Cretaceous 
but thus far the writer has been unable to discover any 
widespread physical break within the Asuncion group 
that would justify such a division. Occasional pholas- 
bored zones occur in the Moreno formation but they 
appear to be local and are not confined to any one 
horizon. They could be caused by local basin filling in 
excess of sinking as well as by uplift. 

There is great lateral variation in these sediments and 
it is not always possible accurately to trace the contacts 
between the various formations; this is particularly true 
of the gradational contact between the restricted 
Panoche and the Moreno. It is probable that this con- 
tact, as mapped north of Coalinga, frequently trans- 
gresses time from place to place, especially near the 
mouths of Upper Cretaceous streams where sands, iden- 
tical with the Panoche, were deposited at the same time 
as shales identical with the Moreno were being deposited 
elsewhere. However in spite of such lateral variations 
Panoche and Moreno are useful lithologic divisions which 
can be followed from Coalinga northward to the Mount 
Diablo region. The Garzas may be equally extensive 
but it is only locally exposed because of overlap by 
Tertiary sediments and alluvium. When followed west- 
ward about the north end of the Coalinga anticline the 
Moreno becomes sandier and less organic and finally 
loses its distinctive appearance. The lithologic divisions 
so distinctive along the west side of the San Joaquin 
Valley can not be recognized within and to the west of 
the Diablo Range and new divisions must be made. 

The maximum thickness of the Asuncion group on 
the west side of the San Joaquin Valley north of Coa- 
linga is 17,000 to 18,000 feet but there'are noteworthy 
variations in thickness due both to original thinning and 
late faulting. The most striking example of local thin- 



Central Coast Range s — T aliaferro 



133 



ning caused by an initial irregularity in the basin of 
deposition occurs in the vicinity of New Idria, on the 
northeast flank of the Coalinga anticline which is here 
made up of Franciscan sediments and volcanics intruded 
by a thick sill of serpentine. These rocks, which are 
folded into a broad but steep-sided dome, are overlain 
on all sides by steeply dipping Asuncion sediments. In 
the vicinity of New Idria the contact is a thrust fault 
which dips steeply southwest but along most of the con- 
tact, which measures more than 25 miles, the Asuncion 
sediments rest unconformably either on Franciscan sedi- 
ments or serpentine, without any intervening Pacheco, 
and the basal beds frequently contain abundant debris 
of the underlying rocks. The thinning in the vicinity 
of New Idria is not due to the faulting but to the pres- 
ence of a submerged bank in the basin of deposition; 
all formations are present and all are greatly thinned. 
This part of the Coalinga anticline was uplifted and 
broadly arched prior to the deposition of the Pacheco 
and probably stood out as a low island during that time 
and the beginning of the deposition of the Asuncion; 
it was finally submerged and covered with sediments 
during Asuncion time. In northwestern Stanislaus 
County, west of Ingram Creek, the Mount Oso anticline 
causes a local thinning in the Panoche sandstones but not 
in the Moreno shales. This appears to have been 
another irregularity in the Upper Cretaceous sea. The 
buttressing effect of the Cretaceous Mount Oso anticline 
had a pronounced influence on the structures formed in 
the late Tertiary. 

The exact limits of the Asuncion group, in terms of 
the European section, are not known but the group is 
believed to represent all of Cretaceous time after the 
Turonian. However the Upper Cretaceous faunas will 
have to be better known before a definite statement can 
be made. That the Cretaceous section along the west 
side of the San Joaquin Valley north of Coalinga con- 
tains the latest known stages of the Upper Cretaceous is 
indicated by the faunas of the Garzas beds and espe- 
cially by the saurian remains. According to Professor 
C. L. Camp a recently discovered Garzas mososaur shows 
more advanced features than the Maestrichtian moso- 
saurs of Belgium or a mososaur from the Moreno. Thus 
it is possible that the Garzas beds represent the Danian. 
The writer simply offers this as a suggestion as he is 
aware that the Maestrichtian and Danian are not found 
in the same locality in Europe and that there has been 
a long controversy regarding the relation of these two 
uppermost stages of the Cretaceous and that the inclu- 
sion of the Danian in the Cretaceous has been ques- 
tioned. 

It is not certain that the Asuncion group in the 
Santa Lucia Range and elsewhere is equivalent to all 
of the time represented by the Asuncion group north 
of Coalinga. However the faunas of the Santa Lucia 
Asuncion are known to represent restricted Panoche, 
Moreno, and Garzas. 

In the Orchard Peak region, in the northwestern 
corner of Kern County, the slight evidence available 
indicates that Asuncion sediments overlie the Lower 
Cretaceous Shasta without any intervening Pacheco. 
However to the northward, in the wide Castle Mountain 
syncline, it is believed that both the Pacheco and Asun- 
cion are present. 



Both divisions of the Upper Cretaceous are repre- 
sented in the thick and widely distributed sediments 
which extend northwestward through Santa Barbara and 
San Luis Obispo Counties, but at present the relative 
proportions of the two and the relations between them 
are not known. Southwest of La Panza Mountains 
about 3,000 feet of Upper Cretaceous sandstones and 
conglomerates rest unconformably on a much thicker 
section of Upper Cretaceous sandstones and shales but 
as the faunas from this region are so meager it is impos- 
sible to make any statement regarding the position of 
this unconformity in the Upper Cretaceous. 

Little is known regarding the position in the Upper 
Cretaceous of the beds in the Santa Cruz Mountains 
but the meager fauna reported from the sediments 
extending along the coast from Pescadero Point to Afio 
Nuevo Point indicates that they are to be correlated 
with the Asuncion group. 

The La Panza Mountains-Gabilan Range region was 
probably partly emergent during the deposition of the 
Asuncion but the emergent area does not correspond 
to the hypothetical land mass of Salinia as there are 
thick Upper Cretaceous sediments along the western 
part and well into the area supposed to have been 
included in "Salinia." The very thick Asuncion sec- 
tions and the fact that so much of the sediments are 
shales in the latitude of Paso Robles and to the south- 
east of Parkfield indicate that the southern part of the 
Gabilan mesa was submerged. The northern part of Gabi- 
lan mesa and possibly a part of Diablo Range were emer- 
gent and contributed debris both to the east and west. 

In the Santa Lucia Range, Asuncion sediments rest 
unconformably on practically all earlier rocks and fre- 
quently overlap onto the basement complex. In the 
northern part of the Cape San Martin quadrangle, 
Asuncion fossils have been found close to the base of 
sandstones and conglomerates resting directly on and 
containing abundant debris of Sur metamorphics and 
granodiorite. In the same range, in northern San Luis 
Obispo and southern Monterey Counties there is a defi- 
nite westward coarsening of the Asuncion. Near the 
coast, in the vicinity of San Simeon, Asuncion beds, with 
a thick basal conglomerate containing abundant boulders 
of Franciscan sandstones and volcanics up to 5 feet in 
diameter, rest on the Franciscan with strong (45 degree) 
unconformity. Eastward near the crest of the range 
Asuncion sediments rest unconformably on Franciscan, 
Shasta, and Pacheco with only a thin basal conglomer- 
ate and a greater proportion of shales. In the north- 
ern part of the Santa Lucia Range there appears to be a 
slight coarsening toward the northeast and here the 
Asuncion sediments may have been derived from the 
emergent northern part of the Gabilan mesa. 

In general the Asuncion group has a much wider 
distribution in the central Coast Ranges than the 
Pacheco. It is quite possible that the original distribu- 
tion of the Pacheco was as great as that of the Asuncion 
and that a large part was removed as a result of the 
Santa Lucia orogeny. 

Thus far it has been impossible to correlate either 
the Pacheco or Asuncion groups with the sediments at 
the type section of the Chico, on Chico Creek, Butte 
County, on the east side of the Sacramento Valley. 
About 2,000 feet of sediments are exposed on Chico 
Creek and there are said to be 12 fossiliferous horizons 



134 



Geologic History and Structure 



[Chap. V 



distributed almost from top to bottom. These sediments 
rest on highly metamorphosed Sierran bed rock and dip 
gently westward. Considering the very fossiliferous 
character of these beds it is strange that a more positive 
correlation with Upper Cretaceous sediments in other 
parts of the State has not been made. The faunas seem 
to be more closely related to the Pacheco than the Asun- 
cion but there are some forms which are characteristic 
of the latter. This locality is more than 125 miles from 
any occurrence of either Pacheco or Asuncion sediments, 
as defined previously, and this might account for the 
difference in the faunas. Although it is admitted that 
there is no very positive evidence on the subject the 
writer is inclined to the belief that the sediments on 
Chico and adjacent creeks, the type section of the Chico, 
represent parts of both the Pacheco and the Asuncion 
groups. The Chico Creek beds were deposited on the 
margin of the Upper Cretaceous basin, on the rigid 
Sierran basement, where great thinning of the entire 
section would be expected, and in a region unaffected by 
the Santa Lucian orogeny. 

SUMMARY OF THE MESOZOIC 

The Franciscan and Knoxville sediments were de- 
posited in an almost continuously sinking geosyncline 
which covered most if not all of the central Coast 
Ranges. There is no unconformity between Franciscan 
and Knoxville, and Knoxville fossils have been found m 
beds having a Franciscan lithologic assemblage. The 
geosyncline in which these beds accumulated was devel- 
oped between the rising ancestral Sierra Nevada on the 
east and a land mass which lay west of the present coast 
line. Both were chiefly derived from the west. The 
Franciscan is later than the Mariposa of the Sierra 
Nevada, the extreme northern Coast Ranges, and Ore- 
gon. Franciscan and Mariposa are not in contact in 
the central Coast Ranges but in northern California and 
southwestern Oregon unmetamorphosed Franciscan lies 
unconformably on metamorphosed Galice (Mariposa). 

Following the deposition of the Knoxville and occu- 
pying but a brief period of geologic time was the Dia- 
blan orogeny which affected the Coast Ranges as a whole 
but which was strongest in the Diablo and Santa Lucia 
Ranges where the Franciscan and Knoxville were up- 
lifted and eroded prior to the deposition of the Lower 
Cretaceous. In spite of this uplift, the Lower Creta- 
ceous (Shasta group) was deposited in practically the 
same geosyncline as the Franciscan and Knoxville and 
had about the same distribution. 

The Lower Cretaceous (Shasta) was brought to a 
close by the mid-Cretaceous disturbance which frag- 
mented the geosyncline in which the Franciscan, Knox- 
ville, and Shasta were deposited, and formed separate 
basins of deposition separated by uplifted areas. Like 
the preceding Diablan orogeny this diastrophism was 
strongest in the Diablo and Santa Lucia Ranges and in 
the Gabilan mesa. The sediments deposited after this 
disturbance are called the Pacheco group from their 
wide distribution in the quadrangle of that name. Al- 
though the evidence is not entirely satisfactory they are 
thought to represent Cenomanian and Turonian time. 

Following the deposition of the Pacheco sediments 
was another orogenic period which is called Santa Lu- 
cian from its development in the range of that name. 
Strong folding and erosion occurred in the Santa Lucia 



Range and in the southern part of the Diablo Range. 
This orogeny was followed by a very general submer- 
gence which depressed below sea-level most if not all of 
both the Santa Lucia and Diablo Ranges. The La 
Panza Mountains and the Gabilan Range still stood 
above sea-level but were probably much lower and more 
restricted than they are at present and, in places, may 
have been largely submerged, especially toward the close 
of the Cretaceous. 

The Asuncion group was deposited during the period 
of submergence which followed the Santa Lucian orog- 
eny. Again the evidence is not all that it should be 
but the Asuncion is thought to represent the Senonian, 
Maestrichtian, and Danian. This upper division of the 
Upper Cretaceous has a much wider distribution than 
the lower division. A very complete and thick section 
of the Asuncion group is exposed along the west side 
of the San Joaquin Valley. Although extensively de- 
veloped in the Santa Lucia Range it is not known 
whether all of Asuncion time is represented by the 
sediments of this region. 

Table I gives the writer's views on the upper Meso- 
zoic of the central Coast Ranges in outline form. 

TABLE I 
Generalized Table of the Mesozoic of the Central Coast Ranges 



System 


European 
Divisions 


Group 


Formation, Stage 




Danian 

Maestrichtian 

Senonian 


Asuncion group 


Garzas sandstone 
Moreno shale 
Panoche sandstone 


Upper 
Cretaceous 


Unconformity — Santa Lucian orogeny 




Turonian 
Cenomanian 
Upper Albian 


Pacheco group 





Unconformity — Mid-Cretaceous disturbance 





Lower Albian 






Lower 
Cretaceous 


Aptian 
Barrmeian 


Shasta group 


Horsetown stage 




Hauterivian 




Paskenta stage 




Valanginian 









Unconformity — Diablan orogeny 




Aquilonian 
Portlandian 


Franciscan and 
Knoxville 




Upper 
Jurassic 


Nevadan orogeny — intense folding 
and batholithic intrusion 




Kimmeridgian 
Oxfordian 


Mariposa group 
(Sierras) 





Central Coast Range s — T aliaferro 



135 



TERTIARY 
PALEOCENE 

The deposition of sediments containing a late Upper 
Cretaceous fauna was brought to a close by uplift, tilt- 
ing:, and probably folding, but this diastrophism was not 
as important or severe as either the mid-Cretaceous or 
Santa Lucian orogenies. As a rule there is compara- 
tively slight angular discordance between the upper- 
most Upper Cretaceous and the Paleocene and little 
change in the character of the sediments deposited. The 
extent of the disturbance which closed the Cretaceous 
is not known as so little of the Paleocene is preserved 
in the central Coast Ranges. 

In the entire Santa Lucia and Santa Cruz Ranges 
there are but three definitely proven and one doubtful 
occurrence of Paleocene sediments and even the largest 
of these is of small areal extent ; all of the unquestioned 
areas are preserved in synclines. 

The most southerly occurrence in the Santa Lucia 
Range, which is also the thickest, is in the northern 
part of the Adelaida quadrangle 4 miles south of the 
north line of San Luis Obispo County but even here 
the Paleocene sediments are but 1,300 feet thick and 
cover less than a square mile. Although they are in part 
covered by Miocene sediments the small areal extent in 
this particular region is largely due to removal prior 
to the deposition of the Vaqueros. These beds lie 
unconformably on the Upper Cretaceous (Asuncion) but 
the two are almost identical lithologically ; fortunately 
the basal Paleocene conglomerate is usually fossiliferous 
as otherwise there would be great difficulty in separating 
them. The writer has mapped this region very care- 
fully and finds, from cross-sections, that the Cretaceous 
was tilted a maximum of 9 degrees to the southwest and 
at least 2,500 feet removed before the deposition of the 
Paleocene. Owing to the limited areal extent of the 
Paleocene it is impossible to say whether the tilting was 
due to faulting or folding but it is probable that both 
took place. The basal Paleocene conglomerate, which is 
thick and heavy, is largely made up of granite and 
porphyry cobbles and boulders, probably in large part 
derived from lithologically identical conglomerates in 
the Cretaceous but there is also a considerable propor- 
tion of debris of the underlying Upper Cretaceous. 
Martinez sediments have been reported from the Bryson 
quadrangle to the northwest but the writer has found 
an abundant Asuncion fauna, including ammonites, in 
these beds. 

About 200 feet of Paleocene sediments are preserved 
in a syncline near the crest of the Santa Lucia Range, 
at an elevation of about 3.500 feet, 4 miles east of the 
Pacific Ocean in the west central part of Monterey 
County. These rest on Upper Cretaceous (Asuncion) 
beds and both are so similar lithologically that the exact 
contact has not been located. 

The Carmelo series, which occurs in a very small area 
on the coast south of -Oarmel, was first referred to the 
upper Eocene, then to the Upper Cretaceous, and finally, 
on meager and uncertain evidence, to the Paleocene. 
These sediments, which are also lithologically identical 
with the Upper Cretaceous, rest on the Santa Lucia 
granodiorite. If these beds are Paleocene the northern 
part of the Santa Lucia Range must have been uplifted 
and more deeply eroded than the central and southern 



parts of the interval between the Upper Cretaceous and 
the Paleocene. There are other lines of evidence sup- 
porting the idea that the northern part of the range was 
uplifted to a greater extent than the southern part after 
the deposition of the Asuncion but it is not certain how 
much of this uplift was accomplished prior to the 
deposition of the Paleocene. A Paleocene age for the 
Carmelo beds has not been established with certainty; 
the available evidence favors an Upper Cretaceous, 
rather than a Paleocene age for these beds. 

In the extreme northern part of the Santa Cruz 
Mountains, extending some 7 miles southeast of San 
Pedro Point in San Mateo County, there are dark shales 
and thin sandstones overlain by conglomerates and sand- 
stones that were originally referred to the Franciscan 
and subsequently to the Martinez. The greater part of 
these beds, which rest on the Montara (Santa Lucia.) 
granodiorite, are Cretaceous, as shown by the print of 
an ammonite found by Dr. Olaf P. Jenkins. Just what 
part of the Cretaceous is represented by these shales is 
not known as no fossils, other than the one mentioned 
above, have been found. The conglomerates and coarse 
sandstones overlying the dark shales are the only part 
of the section which contain a Paleocene fauna. These 
beds have been greatly folded and faulted and have been 
overridden from the northeast by the Franciscan along 
the Pilarcitos thrust and crushed against the 
granodiorite. 

There are no known occurrences of Paleocene sedi- 
ments in the Salinas or Santa Clara Valleys or in the 
Gabilan Range and few within the Diablo Range. Sedi- 
ments correlated with the Martinez occur along the west 
side of the San Joaquin Valley and extend westward 
into the Diablo Range on both flanks of the Vallecitos 
syncline. They are overlapped both to the north and 
south by upper Eocene beds; on the north they extend 
as far as Ortigalita Creek in Merced County and on the 
south as far as the crest of the Coalinga anticline. 

In the vicinity of San Francisco Bay they occur at 
the town of Martinez (type section) and southward in 
Contra Costa County. Although the lower part of the 
sediments in these two general areas are known to be 
Paleocene there appears to be faunal evidence that 
higher Eocene sediments have been included in the areas 
that have been mapped as Martinez. For this reason 
the term Martinez no longer can be considered as syn- 
onymous with Paleocene. 

The Paleocene in both of these widely separated 
areas is similar lithologically to the Asuncion and was 
originally mapped as Cretaceous. However, the two are 
separated by a disconfonnity which locally becomes a 
slight unconformity. The unconformity on the west 
side of the San Joaquin Valley is never as pronounced 
as that in the Santa Lucia Range. 

The actual extent of the Paleocene sea over the cen- 
tral Coast Ranges can not be determined from the small 
and widely scattered exposures of the sediments. Since 
there were orogenic movements during the Tertiary 
which were stronger than those in the Cretaceous most 
of the Paleocene has been removed by erosion. In the 
Santa Lucia Range there is positive evidence of the 
removal of all of the Paleocene except in two small areas, 
before the deposition of the Vaqueros (lower Miocene). - 
Since the later Tertiarv movements were more severe 



136 



Geologic History and Structure 



[Chap. V 



than those prior to the Miocene it is not surprising that 
so little of the Paleocene remains. The Paleocene sea 
may have covered a large part of the central Coast 
Ranges or it may have been confined to two separate 
basins separated by the Gabilan mesa. The exact extent 
of this sea is not known at present and never may be 
known because of an almost complete lack of evidence. 

The Paleocene is much more closely related to the 
Upper Cretaceous both lithologically and faunally than 
it is to the later Eocene deposits and the disturbance 
following the Paleocene was greater than that between 
the Asuncion and the Paleocene. That there were 
strong movements sometime during the Eocene or Oligo- 
cene is clearly demonstrated in northern San Luis 
Obispo County a few miles northwest of Paso Robles 
where Vaqueros (lower Miocene) rests directly on 
granodiorite on one side of a fault and on the other 
side on at least t>,000 feet of Asuncion and Paleocene 
which dip into the granodiorite. Although this only 
dates the fault as pre- Vaqueros and post-Paleocene the 
faulting must have taken place long before the lower 
Miocene in order to remove so great a thickness of Upper 
Cretaceous and Paleocene. 

Many statements have been made as to the radical 
change in fauna between the Cretaceous and Paleocene. 
It is quite true that a number of species and genera 
died out and new forms appeared but it is equally true 
that many genera are common to both. The writer has 
made a number of collections from both the uppermost 
Upper Cretaceous and the Paleocene and has found, in 
many cases, that thoroughly competent paleontologists 
had great difficulty in distinguishing between them. 

It is suggested that the Paleocene represents a final 
stage in the history of the upper Mesozoic geosyncline 
in which the Franciscan, Knoxville, and Cretaceous 
sediments were deposited. As has been pointed out in 
the preceding pages the upper Upper Jurassic and 
Cretaceous geosyncline had a far from simple history as 
there were interruptions in sedimentation and emergence 
and erosion of ridges during its development. In the 
Upper Cretaceous, particularly, a number of note- 
worthy changes took place in this basin; its western 
margin was uplifted, the Gabilan mesa and the ancestral 
Coalinga anticline began to rise above sea level, and 
there were marked differences in the rate of sinking in 
the northern and central Coast Ranges. Notwith- 
standing these various interruptions this geosyncline 
occupied the present central and northern Coast Ranges 
for a long period of time and received a vast volume 
of sediments. That part of the geosyncline in the pres- 
ent central Coast Ranges and along the western border 
of the San Joaquin Valley received sediments through- 
out the upper Upper Cretaceous; very late Upper 
Cretaceous sediments, probably as late as anywhere in 
the world, were deposited in this region. A weak orog- 
eny occurred at the close of the Cretaceous and there 
was uplift, folding, and erosion in the west but little 
or none in the central part of the basin. Probably gen- 
eral uplift occurred and the seas retreated completely, 
or almost completely, from the geosyncline; but in the 
central part of the trough this uplift appears to have 
been quickly succeeded by down-sinking, and the Paleo- 
cene sea flooded at least parts of the geosyncline. This 
was the last time deposition took place over rather large 



areas of this trough. The changes that had taken place 
previously were of lesser magnitude than the changes 
that took place after the deposition of the Paleocene. 
The available evidence indicates that the final frag- 
mentation of the upper Mesozoic geosyncline took place 
in the Eocene. Great thicknesses of Tertiary sediments 
accumulated but they formed in comparatively narrow 
basins, some of which were at a marked angle to the 
trend of the more extensive and more enduring upper 
Mesozoic trough. 

After the deposition of the Paleocene there appears 
to have been a widespread, although not complete, with- 
drawal of the sea from the central Coast Ranges. In 
restricted areas, deposition seems to have been continu- 
ous from the Paleocene into the lower or even into the 
middle Eocene, but over most of the Coast Ranges there 
is a marked break at the close of the Paleocene. 

EOCENE AND OLIGOCENE 

The preceding discussion has been based very largely 
on field observations made by the writer. No Eocene 
sediments are present in any of the areas mapped in 
detail and only casual observations have been made on 
the Eocene of the central Coast Ranges. Since there is 
little that the writer can contribute that has not already 
appeared in the literature, and which is readily avail- 
able, the discussion of the Eocene and Oligocene will 
be brief and largely confined to those salient events that 
appear to be more or less certain. 

Although there is, already, an extensive literature on 
this subject there is still much that is not clear and a 
great deal of additional field and paleontological infor- 
mation must be accumulated before the details of this 
important early Tertiary history are thoroughly under- 
stood. At present our knowledge of this part of the 
Tertiary is in a state of flux, and the nomenclature and 
correlations are constantly changing. 

There is a thick and important Eocene section in 
the central Coast Ranges but as yet there is no universal 
agreement as to nomenclature and correlation. Several 
formations have been shifted from upper Eocene to 
Oligocene and back again a number of times. There 
are also formations whose lower part is known to be 
upper Eocene and whose upper part is known to be 
lower Miocene but which contain no known Oligocene 
fossils. Whether the Oligocene is a valid division of 
the Tertiary of California is a subject outside the scope 
of the present paper, as is the possibility of what we 
generally consider to be lower Miocene actually being 
Oligocene of the standard European section. The writer 
is familiar with the literature on these subjects but feels 
that, as yet, little approach has been made toward their 
solution and clarification. The terms that are in com- 
mon use in California will be followed. 

Although there are thick sections of lower Eocene 
in local areas, more of the California Coast Ranges were 
emergent than at any time during the upper Jurassic 
and Cretaceous. The Santa Lucia Range, and probably 
most of the Santa Cruz Mountains, and much of the 
Diablo Range stood above sea level, but probably were 
low. At this time the central Sierras were undergoing 
continued erosion, which started in the Cretaceous. 
The warm climate of the Eocene may have been caused 
in part by the disappearance or great degredation of 



Central Coast Range s — T aliaferro 



137 



the western land mass from which the upper Jurassic 
and Cretaceous sediments were so largely derived. This 
land mass was no longer a barrier to warm rains and 
currents. Although much of the Coast Ranges were 
above sea level, especially during the lower Eocene, they 
appear to have been comparatively low, as was much of 
the central Sierra Nevada. 

The lower Eocene (Meganos in the northern and 
central Coast Ranges and Santa Susana in southern 
California) occurs in comparatively small isolated areas 
from Mendocino County on the north to Ventura 
County on the south. Sufficient information is not 
available to outline the paleogeography of the lower 
Eocene but there is nothing to indicate that deposition 
was in a continuous trough. The lower Eocene embay- 
ment of southern California was certainly not continu- 
ous through the present Coast Ranges with the lower 
Eocene embayment of northern and central California. 
The lower Eocene trough may have been continuous 
through what is now the eastern part of the present 
northern and central Coast Ranges and the border of 
the San Joaquin Valley. The Santa Lucia Range, the 
Santa Cruz Mountains, the Salinas Valley region and 
most of the Diablo Range appear to have been chiefly 
above sea level during the lower Eocene but it is pos- 
sible that there w y as a sea-way between the San Joaquin 
Valley and the ocean through San Benito and Santa 
Cruz Counties. 

The middle Eocene sea appears to have had a much 
wider extent and to have flooded much of the Great 
Valley and to have encroached onto the flanks of the 
Sierra Nevada and the northern and central Coast 
Ranges. As used here the middle Eocene includes the 
Capay, Domengine and lone. The rather widespread 
sinking which permitted the middle Eocene flooding pos- 
sibly was accompanied by folding and faulting and the 
post-Paleocene pre-Vaqueros faulting previously men- 
tioned may have occurred at this time, although it may 
have taken place as late as the Oligocene. The middle 
Eocene sediments consist chiefly of sandstones, shales, 
clays, limestones, and coal beds and are usually fine 
grained except on the margins of the land masses. The 
middle Eocene sea spread eastward onto the flanks of the 
Sierra Nevada which, by this time was, in central Cali- 
fornia, a low, deeply weathered land mass. The lone, 
which consists of continental, paludal, and marine sedi- 
ments, was clearly derived from an eastern source which 
had undergone extensive chemical decay. The lower 
gravels of the lone are made up of resistant materials, 
such as quartz and andalusite, and rest on deeply 
weathered bedrock. In some places, especially in Mari- 
posa and Madera Counties, the lower lone gravels are 
largely made up of rounded crystals of andalusite. 

It was during the middle Eocene that the econom- 
ically valuable clays, glass sands, and coal accumulated. 
The glass sands of the Mount Diablo region contain 
small quantities of andalusite derived from the Sierras. 
The middle Eocene along the east side of the Diablo 
Range contains detritus from the Coast Ranges (Fran- 
ciscan and Cretaceous) as well as detritus from a Sier- 
ran source. 

The extent of the encroachment of the middle Eocene 
sea on the Coast Ranges is not yet known but it cer- 
tainly covered the east flank and northern end of the 



Diablo Range and probably a part of the Santa Cruz 
Mountains. It may have covered the northeastern part 
of the / Santa Lucia Range as far south as the latitude 
of King City as, according to Professor H. G. Schenk, 
Eocene Foraminifera are found in shales interbedded 
with massive sandstones below the Vaqueros on Vaquero 
Creek. These beds rest with a light basal conglomerate 
on the Santa Lucia granodiorite. 

Volcanic activity took place in the Sierra Nevada 
during the middle Eocene, as the lone contains both 
rhyolitic and andesitic material. This volcanic activity 
did not take place within the basin of deposition of the 
lone but to the east in the higher parts of the Sierras 
and was subaerial rather than submarine. Rhyolite 
debris is found in the lower part of the lone in Mari- 
posa and Madera Counties and andesitic material in the 
upper part of the lone in Placer and Yuba Counties. 
There were minor submarine outbursts in the Coast 
Ranges as bentonite beds occur in the Domengine. This 
middle Eocene volcanism was of very minor importance 
in both the Sierra Nevada and the Coast Ranges when 
compared with the Miocene and Pliocene volcanism. 

The upper Eocene (Tejon, Markley, Kreyenhagen, 
Gaviota, and Wheatland) has a more limited distribu- 
tion than the middle Eocene. After the maximum 
flooding of the middle Eocene there was an emergence, 
accompanied by slight folding and faulting. There is 
no evidence, however, that mountains of any great eleva- 
tion or extent were formed. There was no profound 
disturbance and the same basins and the same sea-ways 
still persisted but were probably somewhat restricted. 

Evidence for local submarine volcanism in the upper 
Eocene of the central Coast Ranges is found in the 
Kreyenhagen in which thin beds of bentonite, vitric tuff 
and vitric crystal tuff are of common occurrence; these 
have been described previously by the writer. Ande- 
sitic explosions occurred in the Sierra Nevada during 
the deposition of the Wheatland, which has been corre- 
lated with the lower part of the Gaviota. 

The sediments that have been referred to the Oligo- 
cene are less widely distributed than the upper Eocene 
beds but, where present, occupy in general the same 
depositional basins. They generally rest unconform- 
able - on Eocene sediments and are unconformably over- 
laid by the Miocene. In general the unconformity 
between the Miocene and the Oligocene is stronger than 
that between the Oligocene and the Eocene; however, in 
the central part of the Santa Cruz Mountains the San 
Lorenzo (Oligocene?) grades upward into the Vaqueros 
(lower Miocene). The sediments generally regarded as 
Oligocene at present are usually called the San Lorenzo 
group and have been described under the following 
formational names: San Emigdio. and Pleito in the 
southern end of the San Joaquin Valley; Tumey north 
of Coalinga; San Juan Bautista and Pinecate in San 
Benito County; San Lorenzo in the Santa Cruz Moun- 
tains ; San Ramon and Kirker in the Mount Diablo and 
San Francisco Bay regions. In addition to these there 
are certain unnamed beds, generally regarded as Oligo- 
cene, at Wagonwheel Mountain, in the La Panza 
quadrangle, and in the Jamesburg quadrange in the 
northern part of the Santa Lucia Range. Part of the 
land-laid Sespe in southern California must be Oligocene. 
There are red beds lithologically identical with the 



138 



Geologic History and Structure 



[Chap. V 



Sespe in various parts of the central Coast Ranges ; these 
will be discussed with the lower Miocene, Little is yet 
known regarding the Oligocene history of the Sierras 
but it is probable that Oligocene vertebrates will be 
found in that region. 

Volcanism occurred during the Oligocene in the 
Mount Diablo and San Francisco Bay regions where 
more than 100 feet of rhyolite tuff is present in the 
Kirker formation. Some of the Tumey sandstones are 
said to be "ashy." 

The middle Eocene marine embayment which ex- 
tended across the present San Francisco Bay, Santa 
Cruz Mountains, and northern Mount Diablo region to 
the flanks of the central Sierras appears to have been 
uplifted and partially drained on the east in the upper 
Eocene and in the Oligocene, although its western part 
was still submerged. There were probably several 
advances and retreats of the sea after the middle Eocene. 
The San Benito trough seems to have been more or less 
permanent during both the Eocene and Oligocene 
although it is quite likely that there were brief periods 
of withdrawal of the sea. This trough probably was 
the chief sea-way into the San Joaquin basin during the 
upper Eocene and the Oligocene. 

Although there are several exceptions, the beds now 
called Oligocene are more closely related lithologically 
and areally to the Eocene than to the Miocene in the 
central Coast Ranges. 

Because of the comparatively limited distribution of 
the Eocene and Oligocene in the central Coast Ranges 
it is impossible to give as complete an account of the 
various diastrophic events and their importance as it is 
for the preceding and following periods. The discon- 
formities and slight angular unconformities that are 
known in the Eocene and Oligocene might indicate that 
these periods were comparatively quiet, in strong con- 
trast to the preceding and succeeding periods. How- 
ever this seeming lack of important disastrophism may 
be more apparent than real because of lack of evidence 
due to the non-deposition of Eocene and Oligocene sedi- 
ments, over so large a part of the central and northern 
Coast Ranges. The Upper Jurassic and Cretaceous his- 
tory shows clearly that the various diastrophisms were 
strongest in the western coastal region and died out 
eastward ; slight disconformities in the Cretaceous along 
the edge of the San Joaquin Valley represent strong 
movements and large angular discordances in the Coast 
Ranges and the same may be true of the Eocene and 
Oligocene. In order to appreciate the changes which 
took place during the Eocene and Oligocene it is 
necessary to consider the basins of deposition and the 
distribution of the Miocene sediments. A greater pro- 
portion of the central and northern Coast Ranges was 
submerged during the Miocene than at any time since 
the Upper Cretaceous but the Miocene basins do not 
necessarily coincide with those of the Upper Cretaceous. 
The final collapse of the upper Mesozoic geosyncline 
seems to have taken place at the close of the Paleocene 
although there had been earlier fragmentation. That 
all the changes in basins of deposition took place imme- 
diately after the Paleocene is hardly likely but it is 
impossible as yet accurately to date the known dias- 
trophic events which occurred between the Paleocene 
and the beginning of the Miocene. It has been stated 



frequently that the Oligocene was a time of general 
uplift and withdrawal of the sea. That uplift and fold- 
ing occurred in some regions during and after the 
Oligocene is certain but it is probable that the diastrophic 
effects ascribed to this particular time were in part due 
to repeated earlier movements. The changes that took 
place in the central Coast Ranges between the Upper 
Cretaceous or the Paleocene and the lower Miocene can 
not be ascribed to any one particular diastrophic event 
but are probably the general effect of several periods 
of movement. Profound changes occurred and both 
folding and faulting took place; many of the faults 
which became active during the late Tertiary came into 
existence at this time. Although both folding and fault- 
ing took place the evidence available indicates that nor- 
mal faulting, often of great magnitude, predominated 
over folding and thrusting. It was during the upper 
Paleocene-lower Miocene interval that the ancestral San 
Andreas was formed and the tilting of the Gabilan mesa 
took place. A part of the stripping of the Franciscan, 
Knoxville, and Cretaceous from certain areas occurred 
during this interval. The cumulative effects of the 
movements during this interval varied greatly from 
place to place; in the northern part of the Adelaida 
quadrangle, for example, the Vaqueros lies on a slightly 
beveled surface of Upper Cretaceous and Paleocene but 
in the southern part of the same quadrangle the 
Vaqueros transgresses across more than 5,000 feet of 
steeply tilted Upper Cretaceous sediments in less than 
2 miles. 

MIOCENE 

The brief discussion of the Miocene that will be given 
here will be based largely on cartographic units and 
diastrophic events. Faunally it is possible to divide the 
Miocene into three parts, lower, middle, and upper, and 
if these divisions could everywhere be mapped sep- 
arately this would be the most convenient method of 
treatment. Frequently a threefold division can be made 
in the field and the units mapped over wide areas, but 
unfortunately the contacts between the three units 
usually transgress time when followed for any great dis- 
tance. In the Salinas Valley and Huasna regions the 
appearance of the first sands well up in the shale section 
forms a convenient lithologic boundary between the 
Salinas shale and the "Santa Margarita." These sands 
usually contain a good littoral zone megafauna that may 
be correlated with the various divisions of the San Pablo. 
However this is not a time contact, when followed any 
distance, as the sandstones in one region may represent 
a lower horizon than those in another. Furthermore 
the shales immediately below the sandstones frequently 
contain a microfauna that is usually regarded as upper 
Miocene. Thus the first appearance of sandstones, 
creating an excellent cartographic division, did not take 
place synchronously everywhere even though the detritus 
was derived from highlands uplifted by a diastrophism 
which affected most of the Coast Ranges at approxi- 
mately the same time. Although these sandstones are all 
upper Miocene, in the paleontological sense, they repre- 
sent various stages in the upper Miocene from one dis- 
trict to another. 

The contact between the lower Miocene (Vaqueros) 
and the succeeding shales (Temblor, Salinas, etc.) is 
more nearly a time contact than that ordinarily found 



Central Coast Range s — T aliaferro 



139 



between shales and the upper sands but even this trans- 
gresses time to a certain extent. 

Any uplift that took place during or after the Oligo- 
cene was followed by submergence at the beginning of 
the lower Miocene (as the term is generally used at 
present). This submergence does not appear to have 
been accompanied by any noteworthy folding or tilting, 
except in local areas, and the first flooding spread over 
the lowlands and gradually covered higher areas as the 
sinking continued. This lower Miocene sea spread over 
and into a region of varied topography and relief and 
the sediments were deposited under a great variety of 
environmental conditions, such as open coasts, protected 
bays, estuaries, and straits. Furthermore there were 
variations of relief under each of these general environ- 
ments ; open coasts might be low and shelving or they 
might be rugged and precipitous. Because of these 
varied conditions of deposition a great variety of sedi- 
ments were deposited. The clastic sediments range from 
exceedingly coarse conglomerates to fine muds and silts ; 
the organic and chemical deposits range from sandy 
organic limestones to very pure reef limestones ; glauco- 
nitic sandstones are not uncommon. Throughout the 
central Coast Ranges in general the thickness of the 
Vaqueros rarely exceeds 1,500 feet but in the Caliente 
basin 6,000 feet of lower Miocene beds are reported, a 
thickness that cannot be accounted for by simple sinking 
without downwarping. 

In several places in the central Coast Ranges land- 
laid red beds are found beneath the marine Vaqueros. 
These varicolored sediments are similar lithologically to 
the Sespe and were deposited in comparatively small 
topographic basins, under essentially the same condi- 
tions. They represent the waste from highlands sub- 
jected to chemical weathering during the Eocene and 
Oligocene. A few fragmentary mammalian remains 
have been found in these beds by the writer but no 
correlation with any part of the Sespe has been pos- 
sible. Since the upper part of the Sespe is known to 
be lower Miocene these beds are mentioned here rather 
than under the Eocene and Oligocene even though they 
may be, in part at least, Oligocene, or even Eocene 
in age. 

The most extensive occurrences known to the writer 
are in the southern part of the Nipomo quadrangle, in 
the northern part of the Nipomo and the southern part 
of the Pozo quadrangles, and in the Bradley and Ade- 
laida quadrangles, where they attain a thickness of 700 
feet and cover an area of more than 100 square miles. 
Another rather extensive area occurs in the Soledad and 
Jamesburg quadrangles. These land-laid beds rest 
uneonformably on practically all the older formations 
and contain debris of local origin. They accumulated 
in local basins, chiefly the broad flood plains of rivers, 
and were formed both prior to and coincident with the 
marine Vaqueros. The bulk of the varicolored sedi- 
ments below the marine Vaqueros are land-laid but some 
are marine and there are occasional interdigitations of 
red beds in the marine section. 

The Vaqueros sea flooded the areas occupied by these 
land-laid beds quietly and without folding or noticeable 
warping as shown by the absence of any angular dis- 
cordance between them. By the close of the lower Mio- 
cene submergence had been sufficient to flood the low- 



land areas in which these sediments accumulated and 
overlap them. 

By the end of what is generally called Vaqueros 
(lower Miocene) time the ocean had spread over the 
lower part of the present Salinas Valley and had 
encroached from both sides onto the southern end of 
the Santa Lucia Range, parts of which were completely 
covered. A low, island-dotted submarine bank extended 
southwestward from the Santa Lucia peninsula and 
connected with an irregular deeply embayed island in 
the vicinity of San Luis Obispo. The Vaqueros gulf 
(southern Salinas Valley, the eastern part of the Santa 
Lucia and the western flank of Gabilan mesa) was open 
to the southeast between San Luis Obispo and La Panza 
Island and by a broader seaway northeast of La Panza 
Island and thence into the southern end of the San 
Joaquin Valley. Another embayment extended south- 
eastward through the present Santa Cruz Mountains 
into the northern part of San Benito County and prob- 
ably occupied a remnant of the Eocene and Oligocene 
San Benito trough. The western and northern parts of 
the Santa Lucia Mountains, the western part of the 
Santa Cruz Mountains, the Sierra de Salinas and the 
northern end of the Salinas Valley, the Gabilan mesa 
and the Diablo Range were all above sea level. 

In the central Coast Ranges sinking continued with- 
out folding or notable warping into the middle Miocene. 
Unconformities between the Vaqueros and the middle 
Miocene have been reported in southern California but 
the writer has never seen an unconformity at this hor- 
izon in the central Coast Ranges. In this region the 
lower Miocene grades upward into the middle Miocene 
without break. The distribution of the two is not the 
same, as continued sinking flooded wider and wider 
areas ; the middle Miocene therefore has a much greater 
distribution than the Vaqueros. Although the middle 
Miocene overlaps the Vaqueros almost everywhere the 
contact between them is gradational and not uncon- 
formable. In some regions the detrital Vaqueros beds 
grade upward directly into typical organic and chemical 
Miocene sediments but in other places there is. a sandy 
and marly transition zone which may be as much as 
700 or 800 feet thick. 

The Miocene sediments later than the Vaqueros 
show a great variation in lithology but the prevailing 
types are foraminiferal shales, marls, limestones, sili- 
ceous shales, cherts, and diatomites. Where the "Tem- 
blor" sediments overlap the Vaqueros they show all the 
variations previously mentioned under that formation 
but the basal sands are usually quickly succeeded by 
organic and chemical sediments. 

Interdigitations of sandstone are common in the 
shales, especially on the borders of basins of deposition 
and occasionally the shales are largely replaced by 
sandstones. In the central part of the Nipomo quad- 
rangle more than 5,000 feet of shales grade laterally 
into sandstones and these in turn, within a few miles, 
grade back into shales. This local body of sandstones 
within the shales represents the delta of a fairly large 
river which came from La Panza Island to the northeast. 
Variations from sandstone to shale are common and 
represent proximity to the edge of the basin or fairly 
large river deltas. 

Shortly after the close of the Vaqueros the simple 
downsinking which permitted the ingress of the Miocene 



140 



Geologic History and Structure 



[Chap. V 



sea gave place to slow downwarping which accentuated 
and gradually deepened the basins and permitted the 
accumulation of great thicknesses of sediments, pre- 
dominately fine grained, in local areas. No one great, 
and continuous geosyncline existed but deposition took 
place in separate basins. The interbasin areas, prob- 
ably originally above sea level, became submerged by 
the regional downsinking which went on hand in hand 
with local downwarping. In the early stages of down- 
warping there was little tendency for the interbasin 
areas to rise but in the upper Miocene the compressive 
stresses causing downbowing became stronger and cer- 
tain of these areas became slightly uparched, even rising 
above sea level. This gentle downwarping which began 
in the early middle Miocene appears to have been due 
to weak compressive stresses which were the first mani- 
festation of the strong and important diastrophism 
which culminated in the late Pliocene and Pleistocene. 
The rapid lateral variation in thickness shown by 
the Miocene sediments in general is due both to original 
highlands in the Miocene sea and to the development of 
steadily deepening basins by local downwarping. Minor 
faulting may have occurred during the early stages of 
downwarping, especially in the western part of the 
present central Coast Ranges, but the writer yet has to 
see any Miocene basin of deposition that owed its origin 
to continuous sinking along bounding faults. All of 
the available evidence indicates slow downwarping rather 
than faulting. 

In some regions Miocene volcanism began in the 
Vaqueros but over most of the Coast Ranges volcanic 
action did not begin until after the beginning of middle 
Miocene sedimentation. Maximum volcanism appears to 
have begun coincident with or shortly after the begin- 
ning of downwarping. Miocene volcanism as a whole 
will be discussed later. 

During the Paleoeene-lower Miocene interval the 
Gabilan mesa was strongly upfaulted along its eastern 
margin, tilted southwestward and deeply eroded. The 
greatest uplift took place in the vicinity of the northern 
part of the present Gabilan Range and decreased both to 
the northwest and southeast. The western margin of 
this uplifted and tilted block is less definite than the 
eastern margin and is not bounded by a continuous zone 
of faulting. The hypothetical "Nacimiento fault" is not 
a continuous line of faulting but rather a series of dis- 
continuous en echelon faults separated by apparently 
unfaulted areas. This hypothetical fault serves no use- 
ful purpose and only increases the complexity of an 
already complex structural and stratigraphic problem. 
Pre- Vaqueros erosion had removed from this tilted block 
practically all of the late Mesozoic and early Tertiary 
sediments and exposed the bedrock complex. The Mio- 
cene sea encroached eastward on this area but only the 
southwestern margin of the southern end was submerged 
during the Vaqueros. In fact the higher eastern part of 
this block, in the vicinity of the present Cholame Hills, 
was not flooded until the upper Miocene. A direct east- 
ward connection from the Vaqueros gulf to the Ran Joa- 
quin embayment was not established until late in the 
upper Miocene when practically all of the southern end 
of the Gabilan mesa was .submerged. Much of the 
northern end of the Gabilan block was never flooded 
during the Miocene. 



The southern end of the Santa Lucia Range, at least 
as far north as the latitude of San Simeon, was sub- 
merged by the close of the Salinas shale phase of deposi- 
tion. In fact more of the southern end of the Santa 
Lucia Range was submerged at this time than during 
the "Santa Margarita." 

Breccias of the San Onofre type are an interesting 
and locally important phase of the early Temblor. All of 
the occurrences of this breccia are close to the present 
coast line and all are characterized by a considerable 
abundance of Franciscan debris, usually angular and 
unsorted. Two hitherto undescribed occurrences of brec- 
cias of this type have been mapped by the writer. One 
of these is in the southern part of the Adelaida quad- 
rangle a few miles east of the present coast line. This 
breccia, made up of a heterogeneous assemblage of Fran- 
ciscan types, lies on the Franciscan and underlies a 
thick section of typical Miocene shales and volcanics; it 
was clearly derived from the west and is largely if not 
wholly marine. Such breccias have frequently been 
cited as examples of fanglomerates and considered as 
evidence of an arid climate. In the opinion of the writer 
they have, at least in the central Coast Ranges, no cli- 
matic or diastrophic significance but simply represent the 
encroachment of the Miocene sea on a rugged coast 
largely made up of Franciscan rocks. They clearly in- 
dicate the presence of a land mass, or at least a series of 
islands, along the present coast line during the Miocene, 
features that disappeared at a later time, the date of 
which is not definitely known except that it was earlier 
than the Pleistocene. Breccias of this type have no 
definite time significance but simply represent the time 
at which the encroaching sea reached a rugged coast 
underlain by Franciscan rocks. The writer has seen 
similar breccias in the Paskenta (Lower Cretaceous) and 
in the upper Upper Cretaceous. Breccias of the San 
Onofre type have been incorrectly correlated with the 
Big Blue north of Coalinga; the Big Blue is of a later 
date and is diastrophic in origin. 

Many conflicting statements have been made re- 
garding the relation between the Salinas shale and the 
Santa Margarita in the Salinas Valley and adjacent 
regions. For a long time this was regarded as a wide- 
spread and profound unconformity but some 15 years 
ago the idea was advanced that the two are generally 
conformable and that local unimportant unconformi- 
ties are the exception rather than the rule. The writer 
has mapped much of this region in detail and has found 
that both relations exist but that an unconformable rela- 
tion, often profound, is present over wider areas than a 
conformable relation. In the Huasna basin, on the 
Nacimiento River not far from its junction with the Sali- 
nas River, along the west side of the Salinas River north 
of Bradley, and in Reliz Canyon the relations are grada- 
tional and conformable. Along the eastern side of the 
southern end of the Santa Lucia Range, east of Temple- 
ton and in the Cholame Hills, as well as in a number of 
other places the relations are unconformable. 

In many places Santa Margarita sandstones are 
loaded with debris of the Salinas shale both of the limy 
foraminiferal "Temblor" type and the siliceous 
"Monterey" type, and sandstones with a typical Santa 
Margarita fauna have been found resting with marked 
angular discordance on both types of the Salinas shale. 



Central Coast Range s — T aliaferro 



141 



This angular discordance becomes more marked as one 
proceeds westward from the Salinas Valley, and very 
probably eastward as well, as the Santa Margarita sand- 
stones, below the McLure shale, in the Cholame Hills 
and in the region east of Templeton, are filled with 
pebbles of the Salinas shale. There can be no question 
that these shale pebbles are pre-Salinas shale in age 
since they contain abundant Salinas shale foraminifera. 
The acidic volcanic pebbles in the Santa Margarita of 
the type section, about whose source a question has been 
raised in the literature, are derived from Temblor vol- 
canics which are abundant along the crest of the south- 
ern end of the Santa Lucia Range. Pebbles from this 
source occur in the Santa Margarita in many other 
places. 

The evidence afforded by the direct visible uncon- 
formities between the Salinas shale and the Santa Mar- 
garita sandstones and the abundance of Salinas shale 
debris in the Santa Margarita are clear and convincing 
proof of important diastrophism, uplift, and erosion 
prior to the Santa Margarita. The coarse detrital 
nature of the Santa Margarita, particularly the lower 
part, is further proof of uplift and renewed erosion. 
On the other hand, the gradational contact between the 
Salinas shale and the Santa Margarita sandstone, 
observed in many places, is equally convincing proof of 
continuous deposition, even though there is a marked 
difference in the character of the sediments. These 
two strongly contrasted relations are not inconsistent 
or irreconcilable when the nature and extent of the 
diastrophism are taken into account. 

The weak compressive movements which began early 
in the middle Miocene and which resulted in the develop- 
ment of local down warped basins became stronger and 
the pre-existing interbasin areas began to fold and rise 
above sea level while the deeper parts of the pre-existing 
basins continued to receive sediments without interrup- 
tion. This condition was not peculiar to the particular 
time under discussion but occurred again in the very 
late Miocene, in the Pliocene, and even in the Pleisto- 
cene. Many of the apparently mutually contradictory 
relations in the later Tertiary of the Coast Ranges of 
California are due to local diastrophism which deformed, 
often severely, the interbasin areas, while the central 
parts of the basins of deposition were relatively undis- 
turbed and were the site of continuous sedimentation. 

The Santa Lucia Range was elevated and the sedi- 
ments folded just prior to the deposition of the Santa 
Margarita sands ; this diastrophism was sufficient to 
expose beds at least as low as the lower part of the 
Temblor, since pebbles of this age occur in the Santa 
Margarita, and it is possible that a considerable part of 
the shales were removed from what is now the crestal 
region. On the western side of the Salinas Valley, 
where the relations have not been obscured by later 
sediments, there is a gradational contact between the 
upper siliceous shales and diatomites and the sand- 
stones. The gradation may be rather sudden or there 
may be a zone of more than 200 feet of interdigitated 
sandstones and shales. Proceeding westward an uncon- 
formable relation appears which becomes more marked 
as the range is approached. "West of the San Antonio 
River the Salinas shale was folded into an anticline and 
more than 1,000 feet of shale removed before the deposi- 



tion of the sandstones across the beveled surface of the 
shales. The folds established at this time were more 
acutely folded in the late Pliocene and Pleistocene and 
greatly accentuated. Neither the maximum deforma- 
tion of the Salinas shale prior to the deposition of the 
sandstones nor the maximum western extent of the 
Santa Margarita can be determined because of the 
strong later diastrophism and the consequent erosion. 
The contact between the Salinas shale and the Santa 
Margarita is not exposed on the Gabilan mesa west of 
the Salinas Valley except east of Templeton where they 
are in fault contact. However the little available evi- 
dence here indicates that the Salinas shale was folded 
prior to the deposition of the Santa Margarita In the 
Cholame Hills, in the eastern part of the Gabilan mesa, 
the Santa Margarita sandstones are filled with detritus 
of the Salinas shale. However this debris may have 
been derived from the Santa Lucia Range rather than 
from any part of the Gabilan mesa. 

In the Diablo Range, north of Coalinga, this diastro- 
phism is possibly represented by the Big Blue, a great 
lens in the Miocene containing abundant debris of ser- 
pentine. The present crest of the Coalinga anticline 
is made up of a great folded sill of serpentine, emplaced 
in the Upper Jurassic and an uplift in that region in 
the late middle or early upper Miocene would result in 
slides and debris of serpentine. Similar slides and out- 
wash of serpentine, on a smaller scale than the Big Blue, 
occur at the base of the upper Upper Cretaceous on the 
north end of the present exposures of the serpentine. 
The early upper Miocene diastrophism of the Santa 
Lucia Range and that in the Diablo Range, resulting 
in the Big Blue, cannot be correlated definitely at the 
present time but they are thought to be essentially con- 
temporaneous. 

How much of the central Coast Ranges were affected 
by this early upper Miocene diastrophism is not known 
but it was pronounced and widespread in that part of 
the Coast Ranges in which the writer has done detailed 
mapping. It was the result of compressive movements 
and did not everywhere result in uplift. In the north- 
ern part of the Santa Lucia Range it resulted in depres- 
sion and upper Miocene sands and shales were depos- 
ited directly on the bedrock complex. In the Huasna 
basin downwarping continued and the upper Miocene 
sea encroached on the west side of La Panza Island to 
a greater extent than the middle Miocene sea. Since 
the movements were compressive certain regions rose 
and were subjected to erosion and certain regions sank 
and received a continuous supply of sediments. The 
geographic positions of the uplifts and depressions 
have not yet been completely outlined ; they were not 
disposed in regular belts for two reasons. First the 
heterogeneity of the underlying rocks and their various 
reactions to compressive forces and second the hetero- 
geneity of the topographic features, largely an inherit- 
ance from the Paleocene-lower Miocene interval. These 
two factors must have had a very marked effect on the 
location and trends of both uplifts and depressions; 
great irregularities would be caused by these factors 
even though the compressive movements were uniform. 

Late in the Miocene, after the deposition of the 
Santa Margarita sandstones and just prior to the depo- 
sition of the McLure shale, at least a part of the central 
Coast Ranges were again subjected to compressive 



142 



Geologic History and Structure 



[Chap. V 



movements which were weaker than those early in the 
upper Miocene but which, nevertheless produced defi- 
nite and easily recognizable effects. The McLure shale, 
a siliceous sediment with rather frequent beds of ben- 
tonite has a wider distribution than has been reported 
previously in the literature. In addition to its occur- 
rence in the type section and northward it is present 
along the west side of Waltham Canyon and in the 
Castle Mountain Range and Mustang Ridge and thence 
westward across the San Andreas fault in the Cholame, 
San Miguel, and Priest Valley quadrangles. In the 
northern part of the San Miguel quadrangle it reaches 
a thickness of 700 feet; in the central part of the same 
quadrangle it is very thin and grades into sandstones. 
The McLure shale is practically identical lithologically 
with much of the upper siliceous phase of the Salinas 
shale hut all the evidence indicates that it is later since 
Santa Margarita sandstones overlie the Salinas shale 
and the McLure shale overlies the Santa Margarita 
sandstones. If any sediments representing McLure time 
were deposited in the Santa Lucia Range they either 
differ greatly lithologically or have been removed by 
erosion. 

Although the McLure shale is usually unconform- 
able on the Santa Margarita sandstones there are places 
where the contact is gradational. The greatest angular 
unconformity ever seen by the writer is 11 degrees, and 
it is usually less than this. On both sides of Castle 
Mountain Range to the north and south of Smith 
Mountain, the shale rests unconformably on sandstones 
containing a Santa Margarita fauna. Usually there 
are 20 to 40 feet of sandstone at the base of the 
shales and even though these sandstones are identical 
lithologically with the underlying Santa Margarita 
the unconformity is very apparent and usually well 
exposed. Both the McLure and the Santa Margarita 
are folded into overturned and often broken and over- 
thrust anticlines on both flanks of the range, the 
overturning being away from the range on both flanks 
with the overturned axial planes or thrusts dipping into 
the range. The overturning and thrusting took place 
in the late Pliocene and Pleistocene and not between 
the Santa Margarita and McLure. The central part 
of the range is essentially a syncline although compli- 
cated by minor folding and faulting. In the central 
part of the range fossiliferous Santa Margarita sand- 
stones grade upward into the McLure shale without 
break ; this conformable, gradational relationship is 
well exposed on a ridge which trends eastward from 
Smith Mountain. The Santa Margarita is thickest in 
the central part of the range and thins toward each 
side because of truncation which took place between 
the Santa Margarita and McLure. In this locality the 
Santa Margarita was gently and rapidly arched into 
two low anticlines (now the two sides of the range) 
and eroded. They may never have been brought above 
sea level and the erosion may have been marine plana- 
tion. The relations in this region are clear and unmis- 
takable and are a proof of the rapidity with which 
folding can take place. These two anticlines, because 
of weakening by local thinning due to erosion, again 
folded and finally broke during the severe diastrophism 
in the late Pliocene and Pleistocene. The range rose 
along these overturned folds and thrusts. Thus the 
earlier movement, slight though it appears to have 



been, was an important factor in the localization of 
the range. 

On the Gabilan mesa, where the relations have been i 
observed by the writer, there is a gradational contact 
between the Santa Margarita and the McLure. 

The extent of this diastrophism is not known at 
present and may never be known because of the oblit- 
eration of evidence by later more severe movements. 
There is no positive evidence that it affected the Santa 
Lucia Range but when we consider the undisputable 
fact that diastrophism always was more severe in the 
coastal region than in the interior it is reasonable to 
believe that there was at least slight uplift and folding 
in the vicinity of the coast at this time. 

MIOCENE VOLCANISM 

Volcanism was more widespread and severe in the 
Coast Ranges during the Miocene than at any time since 
the Franciscan (Upper Jurassic). The great bulk of 
the igneous activity of the Franciscan, which took place 
well along in the development of a great and rather 
long-enduring geosyncline, was basic and ultrabasic in 
character. That during the Miocene was acidic, inter- 
mediate, and basic, with intrusions of semialkaline rocks 
at about the same time over wide areas. This difference 
in petrographic character may be purely accidental 
or it may be a function of geosynclinal development. 
The Miocene was not deposited in a great, long-endur- 
ing, continuous geosyncline, but in separate basins, in 
few of which were sediments accumulated to a thick- 
ness even approaching that of the Mesozoic geosyncline. 

Little volcanism took place in the Vaqueros com- 
pared with the middle and upper Miocene but there 
appears to have been local, usually unimportant activity. 
Flows of andesite and basalt are reported in the lower 
Miocene in the south end of the San Joaquin Valley 
but it is possible that they may be Temblor. In Ven- 
tura County, south of the South Mountain oil field 
there is a very shallow sill in the Vaqueros which 
broke through its shallow cover and flowed on the sea 
floor during the deposition of the lower Miocene. In 
the northwestern part of the Nipomo quadrangle, east 
of Arroyo Grande, there are local breccias of biotite- 
augite dacite which appear to be in the lower part of 
the Vaqueros. The explosions producing the breccias 
were submarine and came up through the Franciscan 
on submarine banks near the margin of the Vaqueros 
sea. These are the earliest Miocene volcanics known to 
the writer in the central Coast Ranges. 

Although volcanics, either as ash, flows, or agglomer- 
ates are rather widespread in the Miocene of the State 
there are several centers of volcanism in which they 
are exceptionally thick. Evidently a long chain of 
volcanic vents lay in the line formed by the Santa 
Monica Mountains and the Channel Islands where there 
are great thicknesses of andesite flows, breccias, and 
ash, many flows and sills of basalt, and thick sills of 
thomsonite diabase in the Temblor. These have been 
named the Conejo volcanics by the writer. Ash beds 
and flows are present in the Santa Maria district but 
they are not exceptionally thick or numerous. 

Another great center of Miocene volcanism lies in 
the San Luis Obispo-Huasna basin region where there 
are several thousand feet of rhyolite tuffs, augite ande- 



Central Coast Range s — T aliafeero 



143 



site, basalt, and olivine basalt flows; thick sills of 
analeite diabase and numerous plugs of andesite and 
rhyolite porphyries occur. In the southern end of the 
Santa Lucia Range there are rhyolite tuffs and flows 
and sills, flows of olivine basalt, often having a well- 
developed pillow structure, and numerous plugs of rhyo- 
lite porphyry. Rhyolite ash, basaltic peperites, flows 
of basalt and numerous sills of analeite diabase occur 
in the Santa Cruz Mountains. Thin rhyolite ash, flows 
and breccias of basalt, and diabase sills are present in 
the Berkeley Hills, but they are not thick. Basalt 
flows occur in the Miocene of the Point Arena region. 
Aside from bentonized ash there are few volcanics in 
the Miocene in the San Joaquin Valley but there are 
numerous flows in the Cuyama Valley and the Carrizo 
Plain. There is abundant evidence that the volcanics 
were largely submarine; the tuffs and ashy sediments 
are often fossiliferous and the flows are generally inter- 
bedded with sediments containing marine fossils. It is 
possible that in some instances the volcanics accumu- 
lated so rapidly that local evanescent volcanic islands 
were built up, especially in the immediate vicinity of 
vents. The only definite subaerial center from which 
large volumes of volcanics were ejected is on the Gabilan 
mesa west of Soledad. Here rhyolitic material blasted 
its way through granodiorite and accumulated near 
the vent as coarse agglomerates and flows ; finer ash 
was showered into the Miocene sea to the west. 

No single description would fit all of the occurrences 
of Miocene volcanics as the sequence and relative pro- 
portions of the various types vary somewhat. However 
the usual sequence is rhyolite tuffs and flows, flows of 
andesite and basalt, intrusions of sills of analeite and 
thomsonite diabase and intrusions of plugs, sills and 
dikes of soda rhyolite and waning explosive activity. 
This sequence is not always followed ; in the southern 
end of the Santa Lucia Range the earliest volcanism 
resulted in thin flows of olivine basalt which lie beneath 
the rhyolite flows and ash. The most complete sequence 
studied is in San Luis Obispo County and northern 
Santa Barbara County where the following types occur 
in ascending order : first, agglomerates of biotite-augite 
dacite in the Vaqueros ; second, rhyolite tuffs and flows, 
the tuffs greatly predominating over the flows; third, 
flows of augite andesite, basalt and olivine basalt which, 
with the interbedded sediments, are nearly 3,000 feet 
thick; fourth, sills of analeite diabase, often with syen- 
itic schlieren; fifth, plugs and shallow intrusions of 
soda rhyolite and occasionally andesite; sixth, waning 
explosive activity, usually rhyolitic, which continued 
intermittently well into the upper Miocene and possibly 
into the lower Pliocene. 

The sills of analeite diabase are an important and 
widespread phase of the Miocene volcanism. The writer 
has visited practically all the known occurrences of 
these rocks and has examined many cores of unexposed 
sills encountered in deep wells. A rough estimate indi- 
cates that they have a combined volume of not less 
than 20 cubic miles. They vary in thickness from less 
than 50 to more than 500 feet and many may be traced 
for more than 10 miles. They intrude the early rhyo- 
lite tuffs and the andesites and basalts, and appear to 
be earlier than the later rhyolites. No occurrences of 
these rocks are known in the upper Miocene; they are 



confined to a comparatively narrow horizon in the 
middle Miocene. They were intruded into flat-lying 
sediments long prior to their uplift and not long after 
their, deposition; the sills are essentially concordant 
but with occasional transgressive boundaries, causing 
rather sudden thickenings and thinnings. 

Some of the thicker sills show gravitational differ- 
entiation and vary from a pierite at the base to a highly 
feldspathie diabase at the top. Most of them show 
chilled margins of analeite basalt, usually vesicular. 
The sediments adjacent to them are hardened and baked 
for a few feet from the contact. In nearly every case 
they were intruded into shales but occasionally they 
are in rhyolite tuffs or andesites. 

Analeite is present in practically all of these sills in 
the central Coast Ranges and sometimes makes up as 
much as 15 percent of the rock. Although primary 
it is undoubtedly a late magmatic product. Fairly 
coarse soda syenitic phases are present in the majority 
of sills; these represent the last stages of consolidation 
and the character of the residual magma after the crys- 
tallization of most of the minerals. These syenitic 
phases seem to be due to filter pressing in the last stage 
of crystallization. The usual texture of the sills is 
diabasic, with occasional areas of true ophitic texture ; 
the syenitic schlieren are usually hypidiomorphic granu- 
lar and are often coarser grained than the remainder 
of the sill. 

Analeite is present in most of the sills of the central 
Coast Ranges but in southern California it is only rarely 
present, its place being taken by thomsonite, indicating 
a concentration of calcium rather than sodium in the 
late magmatic stage. 

Near the head of White Creek, southwest of that part 
of the crest of the Coalinga anticline occupied by the 
Franciscan (here largely serpentine) is a small stock of 
barkevikite soda syenite. This intrusion, which is ap- 
proximately half a mile long and a quarter of a mile 
wide, is intruded into Upper Cretaceous shales and sand- 
stones which dip southwest at a high angle. Float of a 
similar rock has been found on the north flank of the 
range and there are probably one or more intrusions in 
that rather rough and inaccessible region. The rock 
making up this stock varies widely in grain size and 
relative proportions of the minerals from place to place 
but is usually made up of sodic plagioclase, barkevikite, 
aegirite-augite, aegirite, and analeite with many minor 
accessories such as apatite, prehnite, sphene and pri- 
mary ealcite. The chemical and mineralogical characters 
of this rock more closely resemble those of the analeite 
diabases than any other igneous rocks of the Coast 
Ranges and, in the opinion of the writer, the soda sye- 
nite is a moderately deep-seated phase of the analeite 
diabases and was intruded during the Miocene. 

The andesite and rhyolite porphyry plugs occur in 
three general regions : one is in San Luis Obispo Valley 
where a long line of plugs, forming a chain of conspicu- 
ous and rugged hills, extend from Islay Hill on the east 
to Moro Rock on the west. The easternmost plugs of 
this line are andesite porphyries but the great majority 
are of rhyolite porphyry. In the description of the San 
Luis folio, Fairbanks stated that these plugs were of 
Lower Cretaceous age but the evidence presented for this 
statement is not convincing. The plugs in San Luis Val- 



144 



Geologic History and Structure 



[Chap. V 



ley intrude only the Franciscan and there is no evidence 
as to the time of the intrusion ; the writer has mapped 
many identical plugs to the north and has found them 
to intrude the Miocene in a large number of cases. There 
are a few irregular plugs and sills of rhyolite and ande- 
site porphyry intruded into the Miocene in the western 
part of the Nipomo quadrangle but none of them ap- 
proach the size of the larger San Luis intrusions. There 
is a large group of rather small plugs and sills east of 
Cambria on the San Simeon quadrangle and a line of 
large rhyolite porphyry intrusions along the crest of 
the Santa Lucia Range in the same quadrangle. The 
latter are intruded into Franciscan and Lower and 
Upper Cretaceous beds and came in along a fault as 
plugs and irregular tabular sheets. 

The great majority of these intrusions are rhyolite 
porphyries and are identical mineralogically and chemi- 
cally in all their occurrences. Two of these plugs, on the 
flank of the Santa Lucia Range, have been followed up- 
ward through the Franciscan, the Vaqueros and well up 
into the Miocene shales. As they are followed upward 
they show increasing auto-brecciation, a natural conse- 
quence of their intrusion into water-soaked sediments, 
and finally are found to be completely brecciated. They 
contributed fragments and blocks to the Miocene sedi- 
ments, showing clearly that they broke through on the 
sea floor and were subjected to attack by the waves. 
Some may have formed temporary volcanic islands in 
the shallow Miocene sea. They were not all intruded at 
the same time, as shown by the fact some broke through 
the sea floor during the deposition of the lower cal- 
careous "Temblor" phase and others during the deposi- 
tion of the upper siliceous "Monterey" phase of the 
Miocene. One small plug has been observed to terminate 
upward in a very shallow sill which burrowed its way 
under a thin cover of sediments and finally broke 
through on the sea floor and moved forward as a mass 
of fragments and blocks. It is unlikely that all of these 
intrusions reached the surface ; many probably consoli- 
dated before reaching the sea floor. However, there is 
little difference in texture in these plugs and all are 
shallow intrusions. 

There can be no doubt that the Miocene volcanism 
had a pronounced effect on the character of the sedi- 
ments formed. In practically all regions the sediments, 
prior to the beginning of volcanism are marls, lime- 
stones, and foraminiferal shales, and those formed dur- 
ing and after volcanism are in large part siliceous and 
often diatomaceous. "When examined under the micro- 
scope most of these sediments are decidedly ashy and 
there are frequent layers of ash, often bentonitized. 
Such sediments are not confined to the great centers of 
volcanism but are almost universal. Even where there 
are no flows or intrusions there are beds of ash and ashy 
sediments indicating many small local centers of explo- 
sion. 

There appears to be a rather general belief that the 
siliceous sediments are usually confined to the upper or 
"Monterey" phase and are usually upper Miocene in 
age. The writer has used this term in the present paper 
but without age significance. In some regions the sili- 
ceous phase almost immediately follows the Vaqueros 
and is middle Miocene while in other localities the sili- 



ceous sediments do not appear until a higher strati- 
graphic level is reached. 

The writer previously has expressed his views regard- 
ing the role played by the Miocene volcanism and addi- 
tional work has only tended to confirm these opinions. 

PLIOCENE 

There was no general withdrawal of the sea from 
the central Coast Ranges at the close of the Miocene, 
but certain areas were elevated both by folding and 
faulting and in these areas Pliocene beds rest uncon- 
formably on the Miocene. In other areas the two are 
separated by disconformities, marked by pholas-bored 
surfaces or light gravels and in some areas by continu- 
ous deposition. In the Salinas Valley region the dias- 
trophism between the Miocene and the Pliocene was 
much like that between the Salinas shale and the Santa 
Margarita but seems to have affected a wider area. 
The western part of the Gabilan mesa was little dis- 
turbed and, in the few places where the contact may 
be observed, appears to be gradational. Local fault- 
ing and folding occurred in the Cholame Hills, near 
but not along the eastern border of the Gabilan mesa, 
and there is an angular unconformity of as much as 40 
degrees between the upper Miocene and the lower Plio- 
cene in this region. 

In a broad way the chief basins of deposition in 
the Miocene continued into the Pliocene; in some of 
these regions the seas were restricted by the upbowing 
of the margins but in others the Pliocene sea invaded 
regions not flooded during the Miocene. Land-laid 
deposits, containing vertebrate remains, are numerous 
in the Pliocene both within the Coast Range and along 
the eastern border of the San Joaquin Valley north of 
Coalinga. 

The sediments of the Pliocene vary widely in char- 
acter but in general they are detrital rather than chemi- 
cal or organic. Undoubtedly silts are the commonest 
and most universal types but they do not predominate 
everywhere. Impure diatomaceous shales and light- 
colored impure volcanic ash are not uncommon at a 
number of horizons, particularly in the lower part. 
Sandy limestones, both marine and lacustrine, occur 
occasionally; impure coals are present in a few places. 
In the San Francisco Bay region tuffs, agglomerates, 
and flows of andesite, basalt, and olivine basalt are 
interbedded with the land-laid and lacustrine Pliocene 
sediments and there are a number of rhyolite breccia 
necks intrusive into them. In general the Pliocene 
seas were shallow and the land masses comparatively 
low and well forested. 

Weak diastrophism occurred during the Pliocene 
and there are decided differences in the distribution of 
the various phases, but strong unconformities do not 
exist within the Etchegoin, Purisima, or Orinda groups. 
Overlaps occur but they are due to slow depression and 
local down-bowing. 

Decided faunal changes took place during the Plio- 
cene both among the vertebrates and invertebrates and 
faunal stages may be recognized. However the contact 
between them is gradational and they are not satisfac- 
tory cartographic units. Locally the various lithologic 
units may be mapped but because of rather rapid lat- 
eral variation such units are not satisfactory for corre- 



Central Coast Range s — T aliaferro 



145 



lation from one region to another. The Etchegoin 
group may be divided into the Jacalitos and Etchegoin 
stages but they are not satisfactory mapping units; the 
contact originally drawn between these two stages in 
the Coalinga district clearly transgresses time. How- 
ever, they serve a useful purpose and aid in the inter- 
pretation of slowly shifting Pliocene basins. 

In this paper a somewhat arbitrary division will be 
adopted : the Jacalitos stage will be used as synonymous 
with the lower Pliocene and the Etchegoin for both 
middle and upper Pliocene. In some parts of the cen- 
tral Coast Ranges the upper Pliocene was a time of 
strong and active diastrophism but in others it is rep- 
resented by either marine, lacustrine, or land-laid 
beds. The upper contact of the Pliocene is, in many 
places, arbitrarily placed at the top of the marine sec- 
tion ; the overlying orogenic sediments such as the Paso 
Robles, Tulare, Santa Clara, etc., have been arbitrarily 
placed in the upper Pliocene and the lower Pleistocene. 

In many places the basal beds of the Pliocene con- 
tain rather abundant debris of the Miocene cherts and 
siliceous shales. These siliceous pebbles show a type 
of alteration not seen in similar pebbles in the Santa 
Margarita, an alteration which may have a bearing on 
the climatic and physical conditions of deposition of 
the Pliocene. Siliceous Miocene pebbles and cobbles 
in the Pliocene commonly have an outer rim of chalky 
white alteration, a change which must have taken place 
within the basin of deposition. 

In general the Pliocene contains debris of all the 
older rocks, either Miocene, Cretaceous, Knoxville, Fran- 
ciscan, or basement complex. Many of the pebbles, 
cobbles, and boulders in the Pliocene conglomerate were 
derived from older conglomerates, particularly those 
in the Cretaceous. 

Along the east side of the Santa Lucia Range, in 
the Adelaida, Bradley, Bryson, Priest Valley, King 
City, and Soledad quadrangles, the Pliocene is rather 
thin and is made up of coarse boulder and gravel beds, 
sandstones, and silts and there is a definite westward 
thinning of the sediments. In places the conglomerates 
are thin and are made up chiefly of "rotten-rim" Mio- 
cene chert and shale pebbles but in other areas the 
conglomerates are coarse and thick and made up of 
well-rounded basement complex cobbles and boulders, 
largely derived from Cretaceous conglomerates. The 
coarse conglomerates probably represent deposits near 
the mouths of streams flowing eastward from the Santa 
Lucia Range. 

The writer has obtained many large collections of 
Pliocene fossils from the east side of the Santa Lucia 
Range and the Gabilan mesa ; according to Professor 
B. L. Clark these are all of the Jacalitos stage, the 
Etchegoin apparently not being represented. This 
would indicate a broad uplift and an easterly with- 
drawal of the sea at the close of the lower Pliocene. 
The paleontologieal evidence available at present indi- 
cates that the western margin of the middle Pliocene 
sea lay in the vicinity of the western side of Castle 
Mountain Range and crossed the present San Andreas 
fault zone diagonally and without interruption. 

Along the east side of the Santa Lucia Range, the 
Jacalitos stage rests unconformably on both the Santa 
Margarita and various phases of the Salinas shale ; 



this unconformity becomes progressively more pro- 
nounced westward but the angular discordance is never 
large. How much of the Santa Lucia Range was sub- 
merged during the Pliocene is not known as subsequent 
erosion has removed so much of the evidence ; but it is 
thought that much if not all of the range north of the 
San Luis quadrangle was above sea levei as a com- 
paratively low ridge which became higher and more 
rugged to the north. It was probably well forested, 
as were most of the highlands during the Pliocene, as 
carbonized plant remains are abundant in the sedi- 
ments. The Santa Lucia Range contributed debris to 
the Pliocene sea at least as far east as the northern end 
of Castle Mountain Range. 

In the Salinas Valley and along the western flank 
of the Gabilan mesa the contact between the upper 
Miocene and the lower Pliocene appears to be grada- 
tional. In the Cholame Hills there is a local uncon- 
formity caused by both folding and faulting; the areal 
extent of this unconformity is not known because of 
limited exposures of the contact but it is not thought 
to be very extensive. There is a very general eastward 
thickening of the Pliocene west of the Salinas Valley 
and a marked tendency for the sediments to become 
finer grained. Pliocene sediments continue across the 
San Andreas fault without any change in character 
and thickness except for a continuation of the east- 
ward thickening just mentioned. In this region they 
attain their greatest thickness, more than 8,000 feet, 
in Waltham Canyon and southward where both the 
Jacalitos and Etchegoin stages are present. They again 
thin and coarsen northward toward the Pliocene Diablo 
Range which stood above sea level as a low land mass 
in the southern part but which increased in elevation 
northward. The southern end of the Diablo Range 
during the Pliocene was the ancestral Coalinga anti- 
cline which extended eastward into the Pliocene sea 
as a peninsula. 

During most of the Pliocene there was a sea-way 
from the Santa Cruz-Monterey Bay region diagonally 
across the Coast Ranges through the Priest Valley- 
Waltham Canyon strait into the San Joaquin basin 
but it is possible that this connection was not established 
until late in the lower Pliocene. The northwestern 
part of this sea-way was approximately the same as the 
earlier San Benito trough but the southeastern part 
lay to the south of the older connection. Even though 
such a connection did exist at the beginning of the 
Pliocene it must have been narrow and shallow. The 
principal connection from the open ocean to the south- 
ern part of the San Joaquin Valley during the lower 
Pliocene was into the Santa Maria embayment, around 
the southern end of the Santa Lucia Range, across 
most of the central and southern part of the Gabilan 
mesa, and across the northern *nd of Castle Mountain 
Range. In the middle Pliocene (Etchegoin stage) the 
connection from the ocean around the southern end 
of the Santa Lucia Range was either greatly restricted 
or wholly cut off and the chief connection was through 
the Waltham Canyon-Monterey Bay strait. 

From the evidence afforded by surface exposures the 
Pliocene sea did not extend very far north of Coalinga 
on the east side of the Diablo Range but. very probably, 
there was a comparatively narrow embayment which 



146 



Geologic History and Structure 



[Chap. V 



extended northward beneath what is now the west side 
of the San Joaquin Valley. However there is no indi- 
cation that this narrow arm of the sea had any north- 
ward connection with the ocean. 

During: the lower Pliocene the Sierra Nevada was a 
low land mass sloping gently westward toward the San 
Joaquin basin which, except for its southern part, was 
largely above sea level (except for a possible narrow 
northward embayment west of its present center) but 
which was receiving land-laid sediments derived both 
from the Sierra Nevada and the Diablo Range. At this 
time the northern part of the Diablo Range was prob- 
ably higher and more rugged than any part of the 
Sierras except the crest region but since it was smaller 
and narrower it contributed less sediment. The south- 
ern end of the Diablo Range, the ancestral Coalinga 
anticline, extended as a low peninsula into the lower 
Pliocene sea. Juniper Ridge, to the southwest, was 
either a very shallow bank or a low island. 

West of the southern end of the Diablo Range, in 
the northwestern part of the Priest Valley quadrangle 
and northwestward, there was another basin receiving 
land-laid sediments. This opened northwestward into 
the marine embayment in which the lower part of the 
Purisima was being deposited. To the west and south 
of this was the Santa Lucia Range which was at that 
time lower than the Diablo Range. The northern end 
of the Santa Cruz Mountains and the western part of 
the San Francisco Bay region was a rather rugged 
recently uplifted land mass separated by an interior 
basin from the northern end of the Diablo Range; it 
was in this interior basin that the Orinda was deposited. 
The upper Miocene sea had not completely withdrawn 
from this basin as the lowermost beds of the Orinda 
contain a marine upper Miocene fauna. This basin 
was either slightly uplifted or rapidly filled above sea 
level by the flood plain deposits of the continental 
Orinda. 

If the coarseness and thickness of the lower Pliocene 
sediments on its margins are reliable criteria the 
northern end of the Diablo Range was the highest and 
most rugged part of central California during that time. 

Slight compressive movements must have been going 
on during the lower Pliocene as the basins of deposition, 
both marine and continental, were slowly down-warped, 
permitting the accumulation of both marine and conti- 
nental sediments of great thickness. A corresponding 
upbowing of the land masses probably took place but 
without any decided increase in elevation because of 
continuous erosion. 

Toward the close of the lower Pliocene (Jacalitos 
stage), and probably as a result of the slow compressive 
movements, certain noteworthy changes took place. 
The Santa Lucia Range and much of the Gabilan mesa 
were gradually elevated slightly above sea level and the 
Waltham Canyon-Monterey Bay trough was depressed 
and expanded, forming a fairly broad and continuous 
sea-way from the open ocean to the northwest into the 
San Joaquin basin. These movements were slow and 
comparatively gentle and deposition was continuous in 
the basins: overlaps but not unconformities were the 
result. 

Volcanism took place in the Pliocene and was espe- 
ciallv noteworthy to the north and south of the San 



Francisco Bay region where there are thick flows, tuffs, 
and agglomerates of andesites and basalts and rhyolite 
breccia necks and thin rhyolite tuffs. Both rhyolitic 
and andesitic outbursts occurred in the Sierra Nevada 
and some of the finer material was carried by the streams 
and air currents into the San Francisco Bay region and 
the San Joaquin basin. There is no evidence of Pliocene 
volcanism in the Santa Lucia Range. The subaerial vol- 
canic center at the Pinnacles may have been active dur- 
ing the Pliocene but of this there is no direct evidence. 

The slow and continuous sinking of many of the 
Pliocene basins permitted the accumulation of great 
thicknesses of both marine and continental sediments. 
In the Waltham Canyon region the present thickness of 
the Pliocene is more than 8,000 feet and erosion may 
have removed a part of the section. The maximum thick- 
ness of the Purisima is not less than 9,000 feet and even 
the continental Orinda (including such related Pliocene 
beds as the Siesta) is over 5,000 feet in thickness. In 
the Ventura basin the Pliocene reaches the remarkable 
thickness of 16,000 feet. However, the Pliocene sinking 
can not be regarded as exceptionally rapid when the 
duration of Pliocene time is considered. If that part of 
the Pliocene represented by the marine sediments men- 
tioned lasted for only 5,000,000 years, a figure probably 
well below its actual duration, the annual rate of sinking 
would have been .02 inch for 8,000 feet of sediments. 

The land-laid beds of the Pliocene are nearly every- 
where tinged with red, especially those in lower Pliocene, 
indicating oxidation and considerable chemical weather- 
ing in the land masses from which they were derived. 
This is in strong contrast to the land-laid sediments of 
the late Pliocene and Pleistocene which are largely of 
coarse and angular material derived by rapid mechanical 
destruction of recently uplifted highlands. 

The weak compressive movements which began in the 
middle Miocene and continued at intervals throughout 
the upper Miocene and lower and middle Pliocene were 
greatly intensified in the upper Pliocene and resulted in 
strong folding, thrust faulting, and general uplift. This 
diastrophism was the beginning of the most important 
orogenesis in California since the Sierran revolution in 
the Upper Jurassic. It brought into existence or at least 
accentuated the chief present topographic features of the 
Coast Ranges although many of these, such as the Santa 
Lucia and Diablo Ranges, had had well-defined ances- 
tral forms. The very general uplift of the Coast Ranges 
and the withdrawal of the sea, except from coastal em- 
bayments such as the Ventura and Santa Maria basins, 
was not epeirogenic in nature but orogenic and resulted 
from compressive diastrophic forces which became very 
pronounced in the upper Pliocene. Under the compres- 
sion to which the entire Coast Ranges were subjected the 
sediments were strongly folded and thrust faulted. 
Regions which were upbowed during both the Miocene 
and Pliocene again moved upward ; these upwarps or 
geanticlines had long been interbasin areas, although 
submerged in part from time to time, and received a 
thinner cover of Tertiary sediments than the basins. The 
earliest folding took place along their margins as these 
were zones of thinning sediments along the sides of the 
basins. As the folding continued and spread into the 
basins these first formed marginal folds became accen- 
tuated and as the geanticlines continued to rise became 



Central Coast Range s — T aliaferro 



147 



overturned and finally thrust, the direction of movement 
being from the upfolded region toward the basins. Hence 
the geanticlines rode outward over the basins on either 
side and characteristic structures produced were ranges 
with overturned folds and thrust faults dipping inward 
toward the ranges. The elevation of the present ranges 
was accomplished by upward movement along overturned 
folds and thrust faults. The essential structure of the 
ranges is synclinal, complicated by minor folding and 
faulting ; these uplifted synclines are bordered by zones 
of intense folding and thrusting. Both the Santa Lucia 
and Castle Mountain ranges are excellent examples of 
this type of structure. Again the compressive move- 
ments were stronger near the coast and became less pro- 
nounced eastward. The Diablo Range rose essentially in 
this manner but the margins are not overturned except 
in a few places and thrusts are not as well marked as in 
the more westerly ranges. Many irregularities and com- 
plications were introduced by the nature of the bedrock, 
whether sedimentary or crystalline, and by the topo- 
graphic features existing at the beginning of the folding. 

A complication exists in the Gabilan mesa, which has 
a crystalline basement and a relatively thin blanket of 
Tertiary sediments. This yielded chiefly by faulting, 
because of the rigid nature of the basement, but the sedi- 
ments along its margin have been folded. It appears to 
have been capable of transmitting the stress which was 
directed from the southwest toward the rigid crystalline 
block of the Sierras. 

Naturally the uplifted ranges were immediately at- 
tacked by erosion, resulting in a flood of coarse debris 
which chiefly accumulated in the basins. These sedi- 
ments are both uppermost Pliocene and lower Pleisto- 
cene in age. However, since they constitute a lithologic 
unit and are thought to be chiefly Pleistocene, they will 
be considered under that heading. 

QUATERNARY 
PLEISTOCENE 

Although the Plio-Pleistocene land-laid sediments 
are the result of strong uplift, they do not everywhere 
rest on the Pliocene marine beds with marked uncon- 
formity. Again there is definite evidence of strong 
uplift in certain zones and continuous, or almost con- 
tinuous, deposition in the basins. The strongest uplift 
took place in the west, adjacent to the coast, and 
decreased in intensity toward the east. 

The Plio-Pleistocene beds consist of gravels, sands, 
silts, clays, gypsum, and fresh-water marls and lime- 
stones. They were deposited on broad flood plains, in 
interior basins and in temporary, shallow lakes; lacus- 
trine beds are usually confined to the lower part. They 
are commonly white, gray, tan, buff, and brown in color ; 
only rarely do they show the various shades of pink, 
red, and green so common in the land-laid Pliocene 
sediments. 

Marine equivalents of these beds are confined to 
the coastal embayments. such as the Ventura and Santa 
Maria basins, from which the sea was not completely 
drained by the late Pliocene diastrophism. These 
marine beds are similar in character to the marine 
Pliocene. 

The continental Plio-Pleistocene sediments contain 
debris of all of the older formations. In some places 
the debris is obviously of local origin and consists 



largely of one particular type but in others there is a 
heterogeneous assemblage of many rock types, due either 
to the diverse nature of the adjacent exposures or to 
the presence of a larger stream with an extensive drain- 
age area. In some parts of the Salinas Valley the Paso 
Robles formation is chiefly made up of debris of the 
Salinas shale, in others largely of Franciscan and Cre- 
taceous debris and in others of debris of the crystalline 
basement complex. In many places all of these rocks 
are abundantly represented. 

Because of the fact that these Plio-Pleistocene sedi- 
ments accumulated in basins separated by recently 
rejuvenated and upfolded highlands, many names have 
been given them; such deposits have been called Paso 
Robles, Tulare, Paicines, San Benito, and Santa Clara. 
It is quite true that no positive statement can be made 
regarding the exact equivalence of these beds but it is 
certain that they are due to the same cause, namely 
strong uplift and folding in the late Pliocene. They 
may be called orogenic sediments since they are the 
direct result of the rapid erosion of recently uplifted 
mountains. This orogeny may not have affected all 
parts of the central Coast Ranges at exactly the same 
time but it is essentially one diastrophic event. It is 
not thought that this orogeny occupied any great period 
of time or that any important time difference existed 
from one region to another. If there was any lag in 
the uplift and folding it probably was from west to 
east and the possibility exists that the lower part of 
the Paso Robles might be slightly older than the lower 
part of the Tulare. At the present time no definite 
statement can be made regarding this possibility because 
so little is known regarding the fauna of these beds. 

In many localities it is difficult to map the contact 
between these Plio-Pleistocene continental sediments 
and marine and land-laid Pliocene beds and it is known 
that they have been confused many times in the past. 
On the west side of the San Joaquin Valley the sedi- 
ments mapped as Tulare north of Orestimba Creek 
(southern part of Stanislaus County) contain abundant 
vertebrate remains known to be of lower and middle 
Pliocene as well as of Pleistocene age. In the Salinas 
Valley the contact between the Paso Robles and the 
lower Pliocene (Jacalitos) is very difficult to locate and 
the writer has found marine Pliocene fossils in several 
places in beds formerly mapped as Paso Robles. How- 
ever, both to the east and west of the Salinas Valley 
the Paso Robles rests with marked unconformity on 
Pliocene and older sediments. The contact between 
the Paso Robles and the marine Pliocene is only diffi- 
cult to locate in those basin areas, or in regions under- 
lain by rigid crystalline rocks, which were not folded 
during the late Pliocene diastrophism. 

West of the Salinas Valley the Paso Robles rests 
unconformably on the Pliocene and Miocene and the 
unconformity becomes progressively greater westward 
toward the Santa Lucia Range. West of the San Anto- 
nio River the Paso Robles rests on highly folded Miocene 
beds and in one place transgresses across the Miocene 
onto the Cretaceous. Although the Paso Robles is often 
steeply folded along the east side of the Santa Lucia 
Range the angular discordance between it and the 
older beds is everywhere apparent. Furthermore, the 
Paso Robles frequently contains debris of the marine 
Pliocene. 



148 



Geologic History and Structure 



[Chap. V 



Lacustrine sediments are rather common at several 
horizons in the lower part of the Paso Robles, in the 
Tulare in the Priest Valley quadrangle and probably 
elsewhere, and in the San Benito formation. These are 
usually confined to the lower half of these continental 
formations but it is possible that lakes existed through- 
out the time represented by their deposition, especially 
in the San Joaquin Valley. Evidence for the existence 
of these lakes is the presence of marls and limestones 
and thin-bedded, almost gritless clays, containing fresh- 
water fossils. There are many possible origins for these 
lakes; they may have been formed by original slight 
diastrophic warping of the basins, which is not consid- 
ered likely, by irregularities of sedimentation ; or by 
the interference with natural longitudinal basin drain- 
age by the rapidly growing deltas at the mouths of 
streams from the highlands bordering the basins. As 
these deltas grew and coalesced into broad alluvial 
aprons the lakes would be confined to the central parts 
of the basins and, with continued basin-filling, would 
be obliterated. They also may have been due to a lack 
of well-established longitudinal drainage in the early 
history of the basins. These lakes, especially those that 
existed in the Salinas Valley region, seem to have been 
rather temporary, shallow-water bodies. 

The thickness of these Plio-Pleistocene deposits 
varies but is usually less than 2,000 feet. The present 
maximum thickness of the Paso Robles is about 1,100 
feet, of the San Benito the same and of the Tulare in the 
Priest Valley quadrangle about 1,800 feet. The Tulare 
in the San Joaquin Valley has been reported to be 2,000 
to 3,000 feet in thickness but older beds may have been 
included. 

It is highly improbable that even these compara- 
tively small thicknesses were the result of simple basin- 
filling without downsinking. The rather violent move- 
ments in the late Pliocene, which brought about basin- 
filling, probably gave way to less violent but none the 
less important and continuous sinking of the basins. 
The highlands probably continued to rise as there is no 
tendency for the continental sediments to become finer 
upward, indicating a reduction in elevation of the 
source with the passage of time. The upper part of 
the Paso Robles, the Priest Valley quadrangle phase of 
the Tulare, and the San Benito beds is quite as coarse 
as the lower part. 

It has been stated in the literature that the rather 
rapid sinking of the Pliocene gave way to slow sinking 
in the Pleistocene but there is nothing to substantiate 
this. Even granting that the continental Plio-Pleistocene 
sediments may have accumulated more rapidly than the 
marine Pliocene, the time involved for their deposition 
could have been only a small part of that represented 
by the lower and middle (and probably part of the 
upper) Pliocene. There is nothing to indicate that the 
late Pliocene and early Pleistocene downwarping was 
not as rapid, if not more rapid, than that during the 
Pliocene. 

The deposition of these late Pliocene and early 
Pleistocene beds was brought to a close by an even more 
important and widespread diastrophic event than that 
through which they originated, an event which affected 
not only the Coast Ranges as a whole but also the Sierra 
Nevada. The late Pliocene folds and faults were 
greatly accentuated, the highlands formed at that time 



were again uplifted and new folds were formed. The 
orogenic sediments, Paso Robles, Tulare, etc., were 
folded, in some places so strongly as to be locally over- 
turned. The exact time during the Pleistocene at which 
this event took place is not known with certainty but in 
view of the many subsequent Pleistocene events it was 
probably about mid-Plei«tocene. The great fans which 
border the Sierra de Salinas west of the northern part 
of the Salinas Valley and which are later than the Paso 
Robles contain upper Pleist6cene vertebrates. 

The Santa Luoia, Diablo, Castle Mountain, and 
Gabilan Ranges were greatly elevated and the present 
main drainage lines firmly established. Changes in the 
coast line have taken place since that time but the major 
configuration was much the same. 

The compressive movements that produced this orog- 
eny were much the same as those that took place in the 
late Pliocene. In fact, the orogeny which formed the 
Coast Ranges as we know them today was a two-phase 
diastrophism, each phase being stronger than any pre- 
vious Tertiary movements but of the same general char- 
acter. The mid-Pleistocene diastrophism was the cul- 
mination of the compressive movements which began in 
the middle Miocene and continued through the Miocene 
and Pliocene with gradually increasing severity. Sub- 
sequent Pleistocene movements appear to have been of 
a different character. 

The mid-Pleistocene diastrophism accentuated the 
late Pliocene folds and faults and formed new folds and 
faults which affected the Plio-Pleistocene sediments. 
The uplift of the ranges along the inward-dipping mar- 
ginal faults and folds continued and the ranges were 
widened as well as uplifted. 

The nature of the underlying bedrock naturally con- 
trolled the effects produced by the late Pliocene and 
Pleistocene orogenies. Those areas underlain by thick 
sedimentary prisms yielded by folding and ultimately 
by thrust faulting but those underlain by a crystalline 
basement with a relatively thin cover of sediments 
yielded chiefly by faulting although in some cases fault 
ing in the bedrock resulted in folding in the overlying 
sediments. Where there is a gradual thickening of the 
sediments resting on a rigid basement no sharp line can 
be drawn between the two types of yielding. At pres- 
ent it is impossible exactly to define "thick-blanketed" 
and "thin-blanketed" areas in terms of thickness of 
sediments. 

That part of the Gabilan mesa which lies to the 
north of Paso Robles is an excellent example of the 
yielding of gradually thickening sediments resting on 
a crystalline basement. Prom the Cholame Hills, on the 
northeastern side, to the San Antonio River, on the 
southwestern side, there is a gradual thickening of the 
Tertiary sediments, known from wells, from 3,500 feet 
to 9,000 feet. On the southwest, where the thickness 
is 0,000 feet, the beds are folded, often acutely, and the 
yielding was approximately the same as that observed to 
the west where there is known to be more than twice this 
thickness of Mesozoic and Tertiary sediments. East of 
the Salinas River there are such folds as the Vineyard 
Canyon anticline and the San Miguel dome but both of 
these seem to be connected with bedrock faulting. The 
shortening of the crust brought about by the Pliocene 
and Pleistocene orogenies in the Santa Lucia Range and 
that part of the Gabilan mesa covered by more than 






, 



Central Coast Range s — T aliaferro 



149 



6,000 or 7,000 feet of sediments is more than 20 percent, 
but the shortening on that part of the Gabilan mesa 
underlain by less than 6,000 or 7,000 feet of beds is less 
than 3 percent. The transition from one region to the 
other is not sharp and there is a gradual dying out of 
the folds eastward. However, the figure of 6,000 to 
7,000 feet cannot be taken as a dividing line between 
thin- and thick-blanketed areas. Proceeding northward 
in the Santa Lucia Range, the crystalline basement 
gradually emerges and the Mesozoic and Tertiary sedi- 
ments thin, and the yield is chiefly by faulting. How- 
ever, the beds are acutely folded even where they are 
but a few thousand feet thick. The writer has no inten- 
tion of implying that the crystalline basement was 
folded ; folding in thin overlying sediments resulted 
from movement over the bedrock and faulting. 

The cores of the iiplifted ranges, consisting of Meso- 
zoic sediments or basement complex, were uplifted above 
and thrust over soft Tertiary sediments. The rapid up- 
lift and the great oversteepening of the mountain fronts 
resulted in slides, frequently of great magnitude. Al- 
though any type of rock might slide under such condi- 
tions, the Franciscan, because of its heterogeneous char- 
acter, and the clay shales of the Knoxville and Creta- 
ceous were especially favorable for the development of 
the gigantic slides which took place coincident with the 
uplift of the ranges. That these slides were very early 
features is shown by the fact that many of them have 
been dissected by subsequent erosion. It is not uncom- 
mon to find hills and ridges along the mountain fronts, 
but separated from them, covered by thick slide rem- 
nants isolated from the main slide by erosion. Naturally 
sliding of this type was not confined to the middle and 
late Pleistocene but has been a continuous process. In 
places there is a definite sequence of slides observable; 
in general the magnitude of the sliding decreased with 
the passage of time. These great slides and rock streams 
often obscure the structure of the mountain fronts; a 
very erroneous picture of the structure and areal dis- 
tribution of the rock units appears on several published 
maps because the nature of the slides was not recognized. 
Fortunately the later uplift of the Coast Ranges, which 
resulted in the widespread terraces, enabled many of the 
small streams to cut through the slides ; a careful study 
of practically all of the small, steep-walled stream courses 
is essential to an understanding of the complex structure 
of the mountain fronts. It is not unlikely that the late 
Pliocene orogeny caused the development of similar 
slides but the erosion which resulted in the Plio-Pleisto- 
cene sediments removed all traces of such possible earlier 
features. 

Notwithstanding the recency of the mid-Pleistocene 
faulting there is little direct physiographic evidence of 
the individual faults although many of them were of 
great magnitude and brought about the elevation of the 
ranges. Erosion and reduction of the surface was so 
rapid that all original surface, physiographic effect of 
the faulting, was quickly obliterated. 

In the late Pleistocene in the Los Angeles, Ventura, 
and San Joaquin basins there was comparatively gentle 
folding which formed low folds so recently that they 
have been little modified by erosion. This period of 
folding has not been detected thus far to the west of the 
San Joaquin Valley. Its relation to the period of terrace 



formation is not known, but it may coincide with the late 
warping of terraces. 

TERRACES 

The terraces so well developed along the coast and in 
the interior valleys are later than the mid-Pleistocene 
diastrophism as, in places, they are cut on the beveled 
edges of folded Plio-Pleistocene sediments. The marine 
terraces have been reported to occur at elevations of 
2,000 feet or more, but the writer has never seen any 
above 1,500 feet. In many places well-developed terraces 
may be seen at various intervals from sea level to eleva- 
tions of 1,000 or 1,500 feet. Individual terraces are 
difficult if not impossible to follow from one region to 
another and there is little definite correspondence of the 
various terrace levels over wide areas. Over limited 
areas there may be very definite intervals between ter- 
races ; a few miles away the terraces may be equally well 
developed but the interval may be very different, indi- 
cating either initial irregularities in uplift or warping 
between various uplifts. Furthermore the marine ter- 
races along the coast cannot be correlated definitely with 
the terraces of the interior valleys. There is strong evi- 
dence that the coastal region has, in general, been up- 
lifted to a greater extent than the interior. If the uplift 
had been uniform throughout the Coast Ranges the 
interior valleys would have been well below sea level at 
the time the higher marine terraces were formed, a con- 
dition contrary to the known facts. When a longitu- 
dinal profile of the coast is considered it is clear that 
uplift was not the same everywhere and that there were 
areas, such as San Francisco Bay, that were depressed 
rather than uplifted. It is, of course, impossible to 
state at present how much of this apparent irregularity 
is original and how much is due to later tilting and 
warping but it is believed that at least a part of the 
present irregularities observable were caused by 
inequalities of the original movements responsible for 
the terraces. More quantitative data must be assembled 
before a definite statement can be made regarding the 
type of movement responsible for terrace development. 
These terraces have been cited as evidence of widespread 
epeirogenic uplift but when both the longitudinal and 
transverse irregularities are considered doubt is cast on 
this hypothesis. They might equally well have resulted 
from late, relatively weak orogeny and a broad gentle 
upbowing of the ranges. 

Little definite evidence of the warping of earlier and 
higher terraces can be obtained because they are so fre- 
quently obliterated. The best example of a tilted ter- 
race, known to the writer, is in the vicinity of Half 
Moon Bay. Five miles south of the town the base of 
the terrace sediments is at an elevation of over 150 feet ; 
this pholas-bored surface, cut in Purisima shales and 
sandstones, slopes gently northward and disappears 
beneath the present beach at the town of Half Moon 
Bay. In other regions there is fairly definite evidence 
of the warping of the terraces into low broad anticlines 
and synclines. 

PLEISTOCENE VOLCANISM 

There was little volcanic activity in the central Coast 
Ranges during the Pleistocene when compared with the 
extensive and important volcanism in the Sierra Nevada 



150 



Geologic History and Structure 



[Chap. V 



and in northern California. Pleistocene olivine basalt 
flows and agglomerates occur in the Santa Lucia and 
Diablo Ranges and along the east side of Santa Clara 
Valley but no detailed study has been made of these 
volcanics and little is known regarding them. The 
olivine basalts along the east side of the Santa Clara 
Valley have been referred to the Miocene but, from their 
relation to the present surface, the writer has no hesi- 
tancy in placing them in the Pleistocene. 

The writer has seen but one occurrence in the Santa 
Lucia Range but there may be other undiscovered locali- 
ties. In the Bryson quadrangle a short distance east of 
the main crest of the range and at an elevation of 2,000 
feet olivine basalt flows, breccias, and tuffs occur in a 
structural and topographic basin. The basalt was 
erupted through serpentine and large blocks of serpen- 
tine are common in the agglomerates. The flows and 
fragmental volcanics, which have been folded into a 
syncline, occupy an almost circular area about half a 
mile in diameter. The fragmental beds are soft and 
unconsolidated and obviously have never been buried 
beneath any appreciable thickness of volcanics or sedi- 



ments. The flows are usually glomeroporphyritic, with 
clots of granular olivine up to 4 or 5 inches in diam- 
eter. The only evidence for a Pleistocene age for these 
volcanics is the completely unconsolidated nature of the 
pyroclastics, identity of petrographic character with 
volcanics of known Pleistocene age, and dissimilarity to 
any of the Miocene volcanics. Although the evidence 
is far from conclusive it is believed that they were 
erupted during the Pleistocene. 

East of Gilroy there are identical volcanics which 
are unquestionably Pleistocene because of their relation 
to a very late surface, because they are unfolded while 
nearby Santa Clara gravels are strongly folded, and 
because no debris of the volcanics occurs in the Santa 
Clara gravels. The olivine basalts, flows and pyro- 
clastics near the edge of the San Joaquin Valley south 
of Pacheco Pass are late Pleistocene since they are inter- 
bedded with flat-lying terrace gravels. The nearby vol- 
canics resting on the Franciscan and the more extensive 
areas to the south along the crest of the Diablo Range 
are identical in every respect and are, without doubt, 
late Pleistocene. 



TABLE II 
Periods of Igneous Activity in the Central Coast Ranges 



Age 


Formation, Group or 
Series in Which 
Volcanics Occur 


Geographic Dis- 
tribution 


Petrographic and Petrologic 
Character 


Remarks 


Age unknown but 
either pre-Cambrian or 
lower Paleozoic 


Sur series 


Widespread 


Intermediate and basic volcanics 
now represented by chloritic and am- 
phibolitic schists 




Age unknown, pre- 
Cambrian or lower 
Paleozoic 


Santa Lucia granodi- 
orite intrusive into Sur 
series 


Widespread 


Granodiorites, pegmatites, and 
related plu tonics 




Upper Jurassic 


Franciscan and Knox- 
ville groups 


Widespread throughout 
Coast Ranges 


Chiefly basaltic and andesitic flows, 
tuffs and agglomerates. Basic and 
ultrabasic intrusives 


Largely submarine tuffs, 
flows and agglomerates in 
Franciscan and lower 
Knoxville. Intrusions in 
Franciscan and through- 
out the Knoxville 


Lower Cretaceous 


Shasta group 


Very local. Southeast 
of Parkfield and in Or- 
chard Peak Region 


Rhyolitic? tuffs 


Thin and unimportant tuffs 
probably submarine 


Upper Cretaceous 


Moreno formation 


Very local. Alameda and 
Stanislaus counties 


Bentonitized volcanics 


Thin and unimportant 
tuffs — submarine 


Middle Eocene 


lone and Domengine 


Sierra Nevada and San 
Francisco Bay region 


Rhyolitic and andesitic tuffs 
and agglomerates 


Chiefly explosive. Possibly 
flows in Sierra Nevada 


Upper Eocene 


Kreyenhagen formation 


West side of San 
Joaquin Valley 


Dacitic or rhyolitic ash, 
often bentonitized 


Submarine explosive 
activity 


Lower Miocene 


Vaqueros formation 


Southern end of San 
Joaquin Valley (may be 
Temblor) . Nipomo quad- 
rangle. Very local 


Andesitic and basaltic flows. 
Dacite breccias 


Probably subaerial 
explosions 


Middle and upper 
Miocene 


Temblor, Salinas, and 
Maricopa shales, "Mon- 
terey," San Pablo, Santa 
Margarita, McLure, etc. 


Widespread and impor- 
tant, practically through- 
out the Coast Ranges 


Rhyolitic tuffs and flows, ande- 
sitic and basaltic flows, and agglom- 
erates. Analcite diabase sills. Soda 
syenite plugs. Quartz porphyry 
plugs 


Largely submarine but 
with at least one large 
and important subaerial 
volcano 


Lower Pliocene 


Orindan 


San Francisco Bay region 


Andesites, basalts, olivine basalt. 
Flows, tuffs, and agglomerates. Rhy- 
olite breccia necks and tuffs 


Subaerial and sub- 
lacustrine 


Lower and middle 
Pliocene 


Etchegoin 


San Joaquin Valley 


Andesitic tuffs 


May have been a few 
unimportant submarine 
explosions. Much of the 
ash may have come from 
the Sierra Nevada 


Pleistocene 


Later than Santa Clara 
and Tulare 


Santa Lucia and 
Diablo Ranges 


Olivine basalts, often glomeroporphy- 
ritic. Flows and agglomerates 


Entirely subaerial 



Central Coast Range s — T aliapereo 



151 



DIASTROPHIC HISTORY AND STRUCTURE 

Almost every assertion regarding the fundamental 
control of Coast Range structure has been met with a 
contradiction. Folds are the result of faulting and 
die out away from fault zones ; they are independent of 
and unrelated to faulting. Faulting is ancient and 
some faults go back to the earliest decipherable geologic 
history; faults are young, that is, formed during the 
last orogeny, and disappear when sections across them 
are unraveled and reconstructed for an immediately 
preceding period. The San Andreas fault is ancient 
and the horizontal movement is measurable in scores of 
miles; it is very young and the movement is measurable 
in thousands of feet rather than in miles. 

The Coast Ranges have been referred to as a " hetero- 
geneous mobile belt" in which blocks of the crust have 
behaved independently and have moved up and down 
on faults almost at will. Lateral variations in thick- 
ness, so common in the Coast Ranges, have been ascribed 
to deposition in sinking "blocks", bounded by faults 
which were active during the deposition of the sedi- 
ments and which limited the sediments deposited during 
any particular time to these sinking "blocks". This 
well-presented and ably defended concept has been 
opposed by Reed and others who have given a more logi- 
cal picture of folding, faulting, and deposition. 

Anyone unfamiliar with the Coast Ranges of Cali- 
fornia who attempted to read and reconcile all that 
has been written regarding their structure either would 




Fig. 58. Ideal section, showing the effect of late upper Miocene 
anticlinal warping on the localization of the marginal overturned 
folds and thrusts on the two sides of Castle Mountain Range. 
A. Santa Margarita sands were gently folded in two parallel 
anticlines which were beveled before the deposition of the McLure 
shale. B. McLure shale deposited across area; rests on Santa 
Margarita sands except along beveled crests of parallel anticlines 
where it rests on older rocks, either Franciscan. Knoxville. or 
Cretaceous. C. Present section across Castle Mountain Range, 
between Smith and Charley Mountains, showing development of 
the marginal thrusts along the general lines of the upper Mio- 
cene anticlines, which were accentuated, overturned, and finally 
broken and overthrust in the late Pliocene ; thrusting again took 
place along the same general lines in mid-Pleistocene. 



resign the task in utter bewilderment or would be forced 
to accept one or the other of the opposed points of view. 
This would be unfortunate since no one concept is either 
wholly correct or wholly erroneous. 

Broad tectonic syntheses, of the type so commonly 
advanced by Continental geologists, too frequently omit 
those seemingly minor details which are in apparent dis- 
agreement with the particular concept. So many things 
are ignored that the picture tends to become too perfect 
and the pattern too greatly simplified. Many syntheses 
confuse several orogenic episodes and fail to note the 
effect of earlier or later diastrophisms. The writer 
believes that the structures, and even the topography, 
formed by an earlier important orogeny leave their 
imprint on a later and even stronger diastrophism, and 
that many of the current opinions regarding Coast 
Range structure are erroneous because they have con- 
fused the effect of two or more diastrophisms; this is 
particularly true of the San Andreas fault. 

In order to give a background for the complex struc- 
ture of the Coast Ranges as we see it today, it will be 
necessary to recapitulate the diastrophic history pre- 
viously presented. 

Too little is known of the history of the ancient crys- 
talline rocks to make any statement regarding the many 
pre-Franciscan diastrophisms they probably experienced. 
All that is known is that they were folded, dynamically 
metamorphosed, intruded by plutonic and hypabyssal 
rocks, uplifted and deeply eroded prior to the deposi- 
tion of the Franciscan. They contributed debris to the 
Upper Jurassic sediments of the Sierra Nevada and 
were sufficiently denuded to expose the plutonics. The 
fine-grained nature of the upper part of the Mariposa 
indicates that they had been reduced to a comparatively 
low land mass just prior to the Nevadan revolution. 
The first readily decipherable history of the central 
Coast Ranges begins with the formation of the geosyn- 
cline in which the upper Upper Jurassic Franciscan and 
Knoxville and the Cretaceous sediments were deposited. 
This long geosynclinal trough was formed between the 
embryonic Sierras on the east and a rejuvenated land 
mass west of the present coast line. The extent to 
which the Sierra Nevada was iipwarped is not known 
but it is certain that representatives of the present 
exposed crystalline rocks of the Sierras are not found 
as detritus in Franciscan, Knoxville, or Shasta sedi- 
ments. However the higher, little-metamorphosed sedi- 
ments of the Sierra Nevada may have been largely 
removed at this time. The late Jurassic Nevadan orog- 
eny must have occupied a comparatively brief interval 
of geologic time, since beds of known Kimmeridgian 
age were folded and converted into slates. At the same 
time the western land mass was greately uplifted, and 
in the trough between the two land masses, Portlandian 
sediments were deposited. 

During the upper Upper Jurassic (Portlandian and 
Aquilonian) at least 25,000 feet of shallow-water sedi- 
ments and volcanics accumulated. Minor and appar- 
ently local diastrophisms (which may have been severe in 
the unknown region west of the present coast line) caused 
local interruptions in sedimentation and produced local 
disconformities in both the Franciscan and Knoxville. 
The strongest of these movements occurred during the 
deposition of the Knoxville and is recorded in mid- 
Knoxville conglomerates containing de'bris of both Fran- 



152 



Geologic History and Structure 



[Chap. V 



ciscan and lower Knoxville rocks. This mid-Knoxville 
disturbance, so easily seen in the northern Coast Ranges, 
has not yet been recognized to the south. These dias- 
trophisms were not sufficiently severe to leave any 
imprint on features produced at a later time. 

The widespread break between the Upper Jurassic 
and the Lower Cretaceous was caused by diastrophism 
which was most severe in the west and died out east- 
ward. It is represented by a strong overlap in the 
Santa Lucia and northern Diablo Ranges and by a dis- 
conformity to the east. Because of the complex subse- 
quent history, deep erosion in some places and burial 
beneath later sediments in others, the evidence for this 
diastrophism, here called the Diablan orogeny, can only 
be found in a comparatively few localities. Neverthe- 
less, these regions are so widely scattered over the central 
and northern Coast Ranges that it must have affected 
practically all of the California coast. There is evidence 
that this orogeny was most active in the Santa Lucia 
Range along a line, the Las Tables fault zone, which 
yielded by faulting in the Upper Cretaceous, the Eocene, 
the late Pliocene, and probably in the mid-Pleistocene. 
Preserved in synclines along this zone, which goes 
through the Adelaida and San Simeon quadrangles, are 
coarse Lower Cretaceous (Paskenta) breccias. Else- 
where than along this particular line the Paskenta stage 
of the Shasta is made up of the usual dark clay shales 
and thin sandstones. Whether these breccias, which 
contain abundant angular blocks of the Franciscan up 
to 12 feet in diameter, represent uplift by folding or 
faulting is not known but since the breccias are so coarse 
along the Las Tables zone and become finer so rapidly 
away from it, it is thought that they represent uplift by 
local faulting. If this undoubted uplift within the 
Santa Lucia Range was accompanied by faulting along 
the Las Tables line, this is the earliest movement, known 
to the writer, along any fault active during later orog- 
enies. The effect of the Diablan orogeny on later dias- 
trophisms must have been slight in general, but at least 
it is known to have been most severe in regions such as 
the Diablo and Santa Lucia Ranges which were after- 
wards strongly deformed. There is some evidence that 
faulting took place along a line which was active during 
several succeeding periods. 

In the late Upper Jurassic sills, laccoliths, and irreg- 
ular bodies of ultrabasic rock, now largely serpentinized, 
were intruded into both Franciscan and Knoxville prior 
to the deformation of either, as the sills are folded with 
the enclosing sediments. The higher of these sills and 
irregular bodies reached, in some places, almost to the 
top of the Knoxville. In a few places they were exposed 
by erosion between the Knoxville and Lower Cretaceous, 
as shown by serpentine debris in the Paskenta. A few 
miles southeast of Wilbur Springs, in Colusa County, 
there are thick and extensive serpentine mud flows in 
Paskenta shales. Some of these intrusions are locally 
more than 5,000 feet thick, and it is only reasonable to 
believe that they caused local uplift. West of Paskenta, 
in Tehama County, a very thick and irregular body of 
serpentinized peridotite clearly caused a local uplift in 
the Knoxville prior to the deposition of the Paskenta. 
The thick serpentine sill or laccolith now exposed in 
the crest of the Coalinga anticline in southern San 
Benito and Fresno Counties may very well have caused 
local uplift and may have been the fundamental cause 



of the localization of the Coalinga anticline. The gen- 
eral belief has been that the Coalinga anticline was first 
folded in the Upper Cretaceous; but the intrusion of a 
body of serpentine at least 4,000 feet thick in this local- 
ity may have been more effective in producing the 
observed results. Folding in the Upper Cretaceous may 
have accentuated the effect, but the possibility of uplift 
by intrusion can not be ignored. 

Notwithstanding the widespread nature of the Diablan 
orogeny there is no evidence that the Franciscan-Knox- 
ville geosyncline was separated into two or more basins 
of deposition. It may have been somewhat narrowed 
in an east-west direction and local islands may have 
been formed which stood above sea level for a short 
time, but deposition continued after a very brief interval 
in at least a large part of the original basin. Again the 
rapidity of diastrophism is demonstrated ; the Knoxville 
immediately below the Diablan unconformity represents 
a very late stage in the Jurassic and the Shasta imme- 
diately above a very early stage in the Lower Creta- 
ceous. 

There is no evidence for and much against the exist- 
ence of the hypothetical land mass of Salinia during the 
Upper Jurassic and Lower Cretaceous. It is possible 
that the present La Panza Mountains extended a short 
distance northward as a peninsula and a low but sub- 
merged bank continued to the north causing a local thin- 
ning of the Franciscan and Knoxville. 

At least 5,000 feet of predominantly fine-grained 
shallow-water marine elastics accumulated during the 
Lower Cretaceous, which appears to have been a time of 
quiet deposition uninterrupted by diastrophism. 

Widespread uplift and erosion occurred after the 
deposition of the Shasta and again in the Upper Creta- 
ceous. The Upper Cretaceous has been divided by the 
writer into the Pacheco below and the Asuncion above, 
separated by the Santa Lucian orogeny; the Pacheco 
is separated from the Shasta by the mid-Cretaceous dis- 
turbance. It is not always possible to separate the 
effects of these two Cretaceous diastrophisms, but each 
appears to have been stronger and more extensive than 
any movements during the Upper Jurassic and Lower 
Cretaceous. The effects of both were greater in the west 
and died out eastward. In the Santa Lucia Range both 
are represented by profound unconformities which, on 
the west side of the San Joaquin Valley, are simply 
disconformities. Since these two orogenies and the dis- 
tribution of the Pacheco and Asuncion groups have 
been discussed previously, only their combined effect 
will be considered here. 

The combined effect of these diastrophisms was pro- 
found and marked the beginning of the break-up of 
the Mesozoic geosyncline. As a result of the mid- 
Cretaceous disturbance, a broad area roughly corre- 
sponding to the hypothetical land mass of Salinia was 
uplifted and stripped of its cover of Franciscan, Knox- 
ville, and Shasta. The uplift was accomplished either 
by broad arching or faulting or both; local faulting is 
known to have taken place, but it is thought that the 
uplift was chiefly due to broad warping which was 
greatest in the vicinity of the present Gabilan and 
northern Santa Lucia Range. The wide exposures of 
crystalline basement rocks in these areas are an inherit- 
ance from the Upper Cretaceous orogenies, accentuated 
by faulting and tilting in the Eocene. 



Central Coast Range s — T aliaferro 



153 



The southern part of the Gabilan mesa and prac- 
tically all of the Santa Lucia Range as well as the Santa 
Cruz Mountains were submerged during Asuncion time 
and buried under an unknown thickness of sediments. 
These were in part removed as a result of uplift and 
erosion in the Eocene. The only part of "Salinia" 
that was emergent during the deposition of the Asuncion 
was the Gabilan Range, which forms the northern part 
of the more extensive feature known as the Gabilan 
mesa. 

Although the Upper Cretaceous orogenies were of 
great importance and affected a large part of the central 
Coast Ranges they did not split the Mesozoic geosyncline 
into completely separated hasins. By the close of the 
Upper Cretaceous most of the original trough in the 
central Coast Ranges was flooded, with the exception 
of the Gabilan Range, which probably stood as an island 
in the late Upper Cretaceous sea. The Upper Cretace- 
ous movements appear to have been essentially parallel 
to the main axis of the trough, in marked contrast to 
the Eocene faulting which finally fragmented the 
Mesozoic geosyncline and cut across its trend at an 
angle. 

The mid-Cretaceous and Santa Lucian diastrophisms 
had a profound effect upon the subsequent history of 
the central Coast Ranges, as they resulted in the removal 
of a thick prism of Upper Jurassic and Lower Cre- 
taceous sediments from a central block, the Gabilan 
mesa. Eocene faulting, tilting, and stripping accentu- 
ated this effect and firmly established the three-fold 
division of the central Coast Ranges south of Monterey 
Bay into two "thick-blanketed" belts separated by a 
belt with a comparatively thin prism of sediments rest- 
ing on a rigid crystalline basement. 

There was slight folding, uplift, and erosion between 
the Cretaceous and Paleocene, but these movements 
were not comparable with those in the Upper Cretaceous. 
In the Santa Lucia Range the Cretaceous was slightly 
folded and eroded before the deposition of the Paleocene 
but there are no overlaps of Paleocene across the 
Cretaceous. Occurrences of Paleocene sediments in the 
central Coast Ranges are so few in number, except 
along the west side of the San Joaquin Valley, that 
little can be said regarding the original basins of deposi- 
tion. However it is believed that the uplift and slight 
folding at the close of the Cretaceous was quickly fol- 
lowed by depression and local submergence of restricted 
troughs which were essentially parallel to the axis of 
the main Mesozoic geosyncline. Although less widely 
distributed and thinner than the Upper Cretaceous, the 
Paleocene sediments have the same geographic distribu- 
tion and are lithologically similar, and there is nothing 
to indicate that any great uplift or widespread erosion 
occurred between them. There was no reshaping of 
the Coast Ranges at this time, and the movements had 
little effect in guiding subsequent diastrophisms. 

As pointed out previously, the almost complete 
absence of Eocene and Oligocene beds over much of 
the central Coast Ranges does not permit a separation 
of the various movements which took place during this 
time; it is only possible to determine the net effects of 
the movements that occurred between the Paleocene 
and the lower Miocene. That several important move- 
ments took place during this long period of time is 
shown by the unconformities and disconformities along 



the west side of the San Joaquin Valley. Since it is 
known that all preceding and practically all succeeding 
diastrophisms were strongest, in the west and decreased 
in severity eastward to the present western border of 
the San Joaquin Valley north of Coalinga, it is only 
reasonable to believe that movements resulting in slight 
disconformities in the east probably produced much 
greater effects in the west. Although it is impossible 
to distinguish between the various movements it is 
known that the sum of these movements was of pro- 
found effect in the shaping of the Coast Ranges. 

The fragmentation of the long-enduring Mesozoic 
geosyncline, begun in the Upper Cretaceous, was com- 
pleted in the Eocene. Deposition no longer took place 
in a long, practically continuous basin of deposition, 
but in basins which lay at a marked angle to the trend 
of the former geosyncline. It is clear that folding took 
place during the Eocene but the available evidence indi- 
cates that more important effects were accomplished by 
profound normal faulting, a type of movement which 
is in marked contrast to the later severe compression 
which resulted in folding, overturning, and thrusting. 

Perhaps the most important result of Eocene diastro- 
phism was the uplift and southwestward tilting of the 
Gabilan mesa along a line which roughly corresponds 
to the present San Andreas fault. Throughout that 
part of the central Coast Ranges northwest of Parkfield, 
in southeastern Monterey County, the northeastern side 
of this block is rather well defined even where covered 
with Miocene and Pliocene sediments, but the down- 
tilted southwestern side is very irregular and only 
occasionally bounded by faults. The theoretical Naci- 
miento fault was created to serve as the western bound- 
ary of the hypothetical land mass of "Salinia," which 
would roughly correspond to the tilted Gabilan mesa. 
Although there are numerous faults in this region, some 
of which date from the Eocene, there are none which 
could, by any stretch of the imagination, correspond to 
the Nacimiento fault. In the tilting of the Gabilan 
mesa the southwestern margin was not everywhere 
faulted, and hence this border is very irregular and 
often indefinite. 

The faulting which caused the tilting of the Gabilan 
mesa can be dated fairly closely both along the north- 
eastern margin and on faults which appear to have 
developed within the tilted block. Many of these faults 
became active during the late Pliocene and Pleistocene 
but usually no difficulty is encountered in separating 
the effects produced in the two widely separated periods. 
Along the northwest side Franciscan, Knoxville, Shasta, 
and Asuncion sediments, usually of great thickness, are 
in contact with the crystalline rocks; sediments as old 
as the Temblor rest on the Mesozoic sediments on the 
northeast side and on the crystalline rocks on the south- 
west side, dating the movements as post-Asuncion 
(upper Upper Cretaceous) and pre-Temblor. Along 
the San Marcos fault, 5 miles northwest of Paso Robles, 
at least 6,000 feet of Asuncion and Paleocene sediments 
dip northeast into granodiorite ; on one side of this fault 
Vaqueros (lower Miocene) sediments rest on grano- 
diorite and on the other on a great thickness of Upper 
Cretaceous and Paleocene, dating the fault as post- 
Paleocene and pre-Vaqueros. Since the removal of this 
great thickness of Upper Cretaceous and Paleocene 
rocks would have required a very appreciable time, it is 



154 



Geologic History and Structure 



[Chap. V 



believed that the faulting occurred fairly early in the 
Eocene. The San Marcos fault, which can be traced 
for about 15 miles, lies somewhere near the very indefi- 
nite, irregufar southwestern margin of the Gabilan mesa 
and is thought to have formed at approximately the 
same time as the parallel ancestral San Andreas, 20 
miles to the northeast. The first discernible movement 
on the San Marcos fault was post-Paleocene and pre- 
Vaqueros but the more continuous fault to the northeast 
can only be dated as post-Asuncion and pre-Temblor 
because of the complete absence of Paleocene and 
Vaqueros sediments along its course. Both faults are 
connected with the uplift of the Gabilan mesa and it 
is believed that both originated in the Eocene. 

Along the ancestral Eocene San Andreas fault the 
movement was largely vertical, the downthrow being on 
the northeast. Faulting may have been preceded by 
broad upwarping in the Eocene, but of this there is 
no positive evidence. Broad upwarping undoubtedly 
occurred in the Upper Cretaceous but strong faulting 
at that time is unlikely as there are thick sections of 
late Upper Cretaceous sediments, containing no coarse 
angular debris of the crystalline rocks, immediately 
adjacent to or but a short distance from the fault. 
Even during the Eocene it is probable that the northern 
end of the Gabilan mesa, the present Gabilan Range, 
stood higher than the southern part, a result of upbow- 
ing during the Upper Cretaceous, accentuated by uplift 
and faulting in the Eocene. 

The writer believes that there is good evidence of 
profound faulting during the Eocene along the north- 
eastern side of the Gabilan mesa at least from Parkfield 
to the latitude of Hollister, a distance of 90 miles. 
Movement undoubtedly continued beyond these limits 
but it is probable that the magnitude decreased in both 
directions. The greatest apparent uplift occurred along 
the east side of the present Gabilan Range but it is 
probable that a part, and perhaps a large part, of this 
movement was caused by upbowing in the Upper 
Cretaceous. 

Movement took place along at least a part of the Las 
Tables fault zone, in the Adelaida and San Simeon 
quadrangles, during the Eocene, as the Vaqueros lies 
on the Franciscan on the northeast side and on Asun- 
cion on the southwest side along a part of its course. 
Although it is certain that the Las Tables zone was 
active in places in pre-Vaqueros and post- Asuncion time, 
the full extent of this movement is not known because 
so much of the evidence has been removed by uplift and 
northeastward thrusting in the late Pliocene and prob- 
ably in the Pleistocene. A very considerable part of 
the late uplift of the southern part of the Santa Lucia 
Range was accomplished by overfolding and thrusting 
along the Las Tables fault zone. 

Along the coast, in the southeastern part of the San 
Simeon quadrangle and the northwestern part of the 
San Luis quadrangle there is a zone of pre-Vaqueros 
and post-Asuncion faulting which appears to have been 
tilted, and probably slightly folded, by later movements. 
Folded Franciscan sediments and volcanics, overlain 
by Vaqueros, lie on the northeast and Asuncion sedi- 
ments, which dip into the Franciscan at an average 
angle of 30 degrees, on the southwest. The relations 
appear to indicate faulting in the Eocene with the down- 



thrown side on the southwest. Other faults in the 
Santa Lucia Range may have been active in the Eocene 
but because of the absence of Tertiary sediments in the 
higher parts of the range there is no positive evidence 
of such movements. 

The downthrown side of the profound Eocene fault 
on the northeast border of the Gabilan mesa was on 
the northeast; in the Santa Lucia Range the down- 
throw was on the southwest. Even though the south- 
western downdropping in the Santa Lucia Range was 
of great magnitude there is no evidence that the region 
was depressed beneath sea level during the Eocene. 
This apparent anomaly may be due to upbowing prior 
to faulting in the early Eocene, similar to that in the 
Upper Cretaceous, or to continuous uplift, coincident 
with normal faulting, during the Eocene. 

The Santa Cruz-San Benito trough developed after 
the early Eocene faulting, as it crosses the ancestral 
San Andreas at a marked angle. The causes of its 
development and localization are not clear, but it 
appears to have developed by downwarping at a marked 
angle to previously established structural lines. Its 
localization may have been greatly influenced by the 
presence of a rigid crystalline buttress in the northern 
part of the Gabilan mesa and the Santa Lucia Range, 
an inheritance from Upper Cretaceous and early Eocene 
diastrophisms, and by the ancestral Coalinga anticline, 
also a relic of earlier movements. By middle and late 
Eocene time an arm of the Santa Cruz-San Benito 
trough probably extended southwestward between the 
Santa Lucia Range and the Gabilan mesa but there is 
no evidence that this arm extended any farther south 
than the latitude of King City or that it ever connected 
with the San Benito trough across the central part of 
the present Gabilan Range. 

It is, of course, possible that Eocene sediments may 
have been widely distributed in the central Coast 
Ranges and removed before the deposition of the Mio- 
cene. If this were the case the widespread removal 
must have been accomplished by general uplift without 
folding for, if folding had taken place, Eocene sedi- 
ments should somewhere be preserved in the deep 
synclines in the region. It is believed that certain 
paleographic maps of the Eocene have indicated a much 
wider extent of the sea than is justified by the evidence 
even though the Eocene was followed by a long period 
of erosion. The upwarping, which accompanied the 
faulting in the early Eocene, is thought to have been 
sufficient to have kept much of the central Coast Ranges 
above sea level. 

There is no evidence that the early Eocene fault 
along the northeastern margin of the Gabilan mesa 
experienced any movement, except where crossed by 
late Pliocene and Pleistocene faults, until the late 
Pleistocene when the present San Andreas fault was 
formed. The region traversed by this fault was eroded 
and much of it submerged and covered with sediments 
in the Miocene, Pliocene, and Pleistocene before a very 
different type of movement took place along it. It did 
not act as a barrier to marine invasions during the 
Miocene and Pliocene. 

Over most of the central Coast Ranges the Miocene 
began with rather quiet and comparatively uniform 
sinking and the topographic depressions formed during 



Centra l Coast Range s — T aliaferro 



155 



the late Eocene and Oligocene were first flooded; as 
sinking continued the seas expanded and covered greater 
and greater areas. The early movement appears to 
have been chiefly widespread sinking with only minor 
downwarping except in local troughs, such as the Caliente 
basin, where an abnormal thickness of Vaqueros is 
reported. Early in the middle Miocene simple sinking 
gave way to slow downwarping of the basins, permitting 
the local accumulation of great thicknesses of Miocene 
sediments. It is believed that the downwarping was 
caused by compressive movements and that interbasin 
areas were actually upbowed at the same time. This 
slow and gentle, but rather continuous, warping of the 
Coast Ranges was the first manifestation of the com- 
pressive movements which reached their culmination 
in the late Pliocene and mid-Pleistocene. That there 
was upbowing as well as downwarping is shown by the 
relations in the southern part of Monterey County. On 
the east flank of the Santa Lucia Range, east of the 
San Antonio River, there are at least 12,000 feet of 
Miocene sediments. In this region the Santa Lucia 
Range was not completely covered by the Miocene sea 
(although it was not far to the south) and the sedi- 
ments thin and become slightly coarser westward toward 
the range. At the beginning of the Miocene the ances- 
tral Santa Lucia Range stood above sea level as a low 
land mass which increased in elevation northward ; 
there is nothing in the character of the sediments to 
indicate that it was either high or rugged. It was 
subjected to erosion and contributed sediments to the 
sinking trough to the east (and very probably to a 
trough to the west) throughout the Miocene. There is 
no evidence that the margin of this trough was faulted 
at any time during the deposition of the Miocene sedi- 
ments and it is unreasonable to postulate an abrupt 
strong marginal flexure to account for the sinking. 
Less than a quarter of the downwarping of the closely 
adjacent trough during the lower and middle Miocene 
would have carried the Santa Lucia Range well below 
sea level, hence it is believed that the sinking of the 
trough was accompanied by upwarping of the range. 
There is definite evidence, which has been presented 
previously, that the range was rather suddenly elevated 
in the late Miocene; it is believed that this uplift simply 
represents an accentuation of the rather continuous 
upwarping which had been going on since the beginning 
of the middle Miocene. 

The compressive forces that produced the Miocene 
troughs and upwarps may have been applied rather uni- 
formly over the central Coast Ranges but they did not 
result in evenly spaced troughs and uplifts because of 
heterogeneities of basement and topography brought 
about by previous diastrophisms. An important and 
rather long-enduring trough developed along the west- 
ern down-tilted side of the Gabilan mesa, west of the 
Santa Lucia Range. The southern end of the Santa 
Lucia Range was flooded but it did not sink to the same 
extent as the basin to the west. Remnants of Miocene 
sediments occur along the west side of the range as far 
north as the Cape San Martin quadrangle and again in 
the Point Sur quadrangle to the north indicating a pos- 
sible trough west of the Santa Lucia Range. The trough 
east of the range continued to sink and expand until 
the southern part of the Gabilan mesa, except for a few 
islands of crystalline rocks northwest of Parkfield, was 



covered. This trough also expanded toward the north- 
west between the Santa Lucia Range proper and the 
Sierra de Salinas (now essentially a part of the Santa 
Lucia Range) and a connection with the present Mon- 
terey' Bay region was established in the upper Miocene. 
The upper Miocene diastrophism, which has been dis- 
cussed previously, uplifted and folded the Santa Lucia 
Range and at least a part of the Diablo Range but depo- 
sition was continuous in the central parts of the basins 
which continued to sink. 

The present crest of the Coalinga anticline, now 
occupied by Franciscan, stood above sea level through- 
out the Miocene. Lower and middle Miocene sediments 
in the Vallecitos syncline contain characteristic Fran- 
ciscan debris, such as benitoite, showing clearly that the 
Franciscan was exposed to the south at that time. 
A peninsula of Cretaceous rocks extended southeastward 
from this island at least as far south as Curry Mountain. 
The southwest side of this island roughly followed, but 
did not necessarily exactly coincide with, a zone of fault- 
ing, the ancestral Waltham Canyon fault. The writer 
is well aware that many conflicting statements have 
been made regarding the Waltham Canyon fault, that 
it has been regarded as of recent origin, and that cross- 
sections have been published showing its disappearance 
in the Miocene. He has mapped those parts of the 
Priest Valley and Coalinga quadrangles adjacent to 
this fault and the relations can only be explained by 
sharp folding and faulting in the pre-Miocene. Space 
does not permit the presentation of the maps, cross-sec- 
tions and explanations necessary to prove this state- 
ment; the briefest statement that can be made is that 
it would be necessary to believe that over 11,000 feet of 
Upper Jurassic and Cretaceous sediments thinned to 
nothing in a distance of approximately 15,000 feet unless 
it is admitted that faulting occurred. The date of the 
faulting is not definitely known but it is believed to 
have been early Eocene. 

At the close of the Miocene that part of the Santa 
Lucia Range between the latitude of Bryson on the 
southeast and Point Sur on the northwest stood above 
sea level as a low, long, narrow island. The Sierra de 
Salinas, most of the Gabilan Range, and the northern 
part of the Gabilan mesa stood as a large island, prob- 
ably higher than the Santa Lucia island. A peninsula 
extended to the southeast at least as far as Lonoak; 
southeast of this peninsula and along the same trend 
were a few small rather rugged islands made up of 
crystalline rocks. East of this peninsula lay the island 
marking the crest of the Coalinga anticline. To the 
northwest lay the long narrow Diablo island. This was 
smaller than usually shown on paleographic maps, as 
the writer has found middle and upper Miocene sedi- 
ments at an elevation of nearly 3,000 feet in eastern 
Santa Clara County. In the troughs between these 
islands a variable, but usually great thickness of Mio- 
cene sediments had accumulated. These sediments, 
thick in the basins, thinned toward these islands, a con- 
dition which aided in localizing overturns and thrusts 
later. These islands were in part due to slight but con- 
tinuous upbowing during the Miocene and in part were 
inheritances from earlier diastrophisms. The thickest 
accumulation of Miocene sediments in Monterey and 
northern San Luis Obispo Counties took place along the 
western down-tilted margin of the Gabilan mesa, which 



156 



Geologic History and Structure 



[Chap. V 



was constantly downwarped by the compressive move- 
ments which began early in the Miocene. 

The effect of movements during the late upper 
Miocene cannot always be evaluated because of removal 
of evidence by later more severe diatrophisms ; this is 
especially true in the Santa Lucia Range. However, 
in the northern part of the Castle Mountain Range 
and in its northern continuation. Mustang Ridge, the 
evidence is clear and unmistakable and has been pre- 
served for many miles on both sides and within the 
range, notwithstanding the severity of the later diastro- 
phisms. Middle Miocene sediments (with a character- 
istic Temblor fauna) are present in this region but 
their distribution is very limited, either because of 
small narrow original basins of deposition or removal 
in the early upper Miocene. Santa Margarita sands 
were deposited over the region on a basement consist- 
ing chiefly of Franciscan but with remnants of Knox- 
ville, Shasta, and Upper Cretaceous sediments. These 
were deposited on a surface of moderate relief and 
their original thickness varies somewhat from place to 
place, but they are usually from 100 to 300 feet in 
thickness. After, or perhaps even during, the deposi- 
tion of these sands, there was gentle anticlinal folding 
along two more or less parallel lines, 6 or 8 miles apart, 
which roughly correspond with the present margins of 
the range; the maximum observed tilt is 11 degrees. 
These two anticlinal ridges, formed within the basin 
of deposition of the Santa Margarita sandstones, were 
planed off, possibly almost as rapidly as they were 
formed by marine planation. The McLure shale, 
usually with a thin basal sandstone, was then deposited 
over the entire region. Where it crosses the two anti- 
clines it lies unconformably on the Santa Margarita 
sands and on the Franciscan. Elsewhere the Santa 
Margarita sands and the McLure are conformable and 
in many places appear to be gradational. This local 
thinning, due to gentle folding before the deposition of 
the McLure, had a marked influence on the localization 
of the overturning and thrusting on the two sides of 
the range, by which action the range was uplifted in 
the late Pliocene and mid-Pleistocene. The accompany- 
ing figure indicates the stages in this process: A shows 
the gently folded Santa Margarita sands ; B the McLure 
shale transgressing across the beveled edges of the sands 
and locally resting on the Franciscan across the anti- 
clinal crests; C is an actual section across the present 
northern end of Castle Mountain Range between Smith 
and Charley Mountains. The localization of the late 
Pliocene and mid-Pleistocene marginal overturning and 
thrusting was only in part caused by the two late 
Miocene anticlinal ridges. East of this range is the 
Walt ham Canyon trough which gradually subsided dur- 
ing the Pliocene and in which fully 8,000 feet of 
Pliocene sands and silts accumulated. Pliocene sedi- 
ments are preserved within the range in synclines but 
they are thinner across the range than on either side. 
Much of this thinning may be due to erosion after 
uplift but rather meager paleontological evidence indi- 
cates that there is a definite thinning of the Jacalitos 
phase across the range. Although this part of the 
Castle Mountain Range was not emergent during the 
deposition of the Jacalitos and Etchegoin phases of the 
Pliocene, it did not sink to the same extent as the regions 
on either side. There is no evidence in the character 



and distribution of the sediments that the two sides 
of the range were active faults during the deposition of 
the Pliocene. It is believed that the gentle and rather 
continuous downwarping of the Priest Valley-Waltham 
Canyon basin was accompanied by upbowing of the 
adjacent range, upbowing so slight that it did not keep 
pace with the general sinking of the region but caused 
a general thinning of the sediments across the range. 
This local thinning also influenced the localization of 
the overturning and thrusting in the late Pliocene and 
mid-Pleistocene. This range is a good example of the 
influence of earlier movements on the localization of 
later and more powerful diastrophisms. 

The movements which closed the Miocene have been 
described previously ; in the west, and possibly over 
much of the central Coast Ranges, they were much like 
those in the upper Miocene in that many of the former 
uplifts were accentuated but deposition was continuous 
in the basins. The Santa Cruz-Priest Valley-Waltham 
Canyon trough was greatly deepened and thick accumu- 
lations of silty sediments took place, especially in the 
northwest and southeast. Sediments did not accumu- 
late to as great a thickness in the central part of this 
trough in central and southern San Benito County. : 
The northern part of this trough corresponded with 
the earlier San Benito Eocene trough but the southern 
part lay to the southwest, rather than to the north of I 
the crest of the ancestral Coalinga anticline. The south- 
east end of the Eocene San Benito trough was still a 
slightly depressed area but it received continental rather 
than marine sediments during the Pliocene. The thick 
accumulation of sediments in sinking troughs and their 
marginward thinning, begun in the Miocene, was 
accentuated in general, by lower and middle Pliocene 
deposition. 

The gentle compressive movements which began 
early in the Miocene reached their first great peak in 
the late Pliocene and their second peak in the mid- 
Pleistocene. Opinions have differed as to the relative 
importance of these two closely related diastrophisms 
and in many instances only one has been recognized. 
In general it may be said that those who have worked 
in the western part of the Coast Ranges have emphasized 
the importance of the earlier and those whose experience 
has been chiefly limited to the eastern part have stressed 
the importance of the later movements. Both were of 
great importance and deformed most, if not all of the 
Coast Ranges; the late Pliocene folding and thrusting 
was especially strong in the Santa Lucia Range, some- 
what less so in the Castle Mountain Range and com- 
paratively weak eastward. In that part of the Diablo 
Range lying in central and northern San Benito County 
the earlier movements were much stronger than the 
later as the Plio-Pleistocene San Benito orogenie sedi- 
ments are only gently folded and occasionally pass 
across strong late Pliocene thrusts without interruption. 
The mid-Pleistocene' deformation, judged by the degree 
of folding of the Plio-Pleistocene orogenie sediments, 
was equally strong from the coast to Waltham Canyon, 
dying out eastward but less rapidly than the late Pli- 
ocene movements. These are broad generalizations only 
and there are local exceptions caused by variation in 
resistance of bed rock and by the presence of earlier , 
folds and faults. 



C K N T R A I, ('OAST R A N E S — T A L I A F E R R O 



157 



The late Pliocene diastrophism not only uplifted the 
ranges by folding and thrusting of their margins but 
also brought about uplift of the Coast Ranges, causing 
a very general retreat of the seas from the entire region, 
except from certain coastal embay ments. The rapid 
folding and uplift of the ranges and the erosion which 
ensued formed thick flood plain and lacustrine deposits 
(Paso Robles, Santa Clara, San Benito, restricted 
Tulare, etc.) in the basins which in general were already 
filled with thick Tertiary sediments. 

Since the late Pliocene and mid-Pleistocene diastro- 
phisms were of the same general character and were 
produced by compressive forces, and since the later 
movements only served to accentuate major features 
formed by the earlier, the effects of the two will be 
treated as a whole. The writer will leave a discussion 
of the ultimate causes of the forces which produced 
the results we see to those who are not satisfied with 
the observation and presentation of known facts but 
must indulge in speculations regarding deep convection 
currents, isostatic adjustments, shifting continents and 
the like. Such speculations, while valuable, all too 
often ignore the array of surface evidence already avail- 
able. It is sufficient to say that observations in the 
Coast Ranges indicate that since the Eocene, at least, 
there has been a constant pressure of the oceanic seg- 
ment against the continent. The compressive forces 
which were brought to bear on the continental margin 
and which culminated in two peaks in the late Pliocene 
and mid-Pleistocene acted on a region of diversified topog- 
raphy and bedrock and variable thicknesses of sediments. 
Much of the diversity in the nature of the bedrock 
was an inheritance from the Upper Cretaceous and 
the Eocene. The three-fold division south of Monterey 
Bay into two belts underlain by a thick prism of pliable 
sediments separated by a central belt underlain by a 
crystalline basement came into existence in the early 
Eocene ; diversities within this central belt also were an 
early feature. The wide exposures of crystalline rocks 
in the northern Santa Lucia Range and in the Gabilan 
Range essentially are due to upwarping in the Upper 
Cretaceous and to block faulting and tilting in the 
Eocene. The thick accumulation of Miocene and Plio- 
cene sediments in basins and their marginal thinning 
across interbasin upwarps, although greatly influenced 
by earlier-formed features, was largely a result of the 
widespread sinking which began in the lower Miocene 
and the compressive forces which began, over most of 
the region, in the early middle Miocene and which deep- 
ened the basins almost continuously, and gently arched 
the interbasin areas. Our present major topographic 
and structural features clearly show the imprint of 
Upper Cretaceous and Eocene movements but their gen- 
eral direction and localization came into existence in the 
early middle Miocene; the strong Plio-Pleistocene dias- 
trophisms followed the major trends established at that 
time. The upwarped areas, originally rather simple, 
in some cases at least, became compound during the 
various minor upper Miocene peaks and developed 
parallel marginal folds along which later overturning 
and thrusting were localized. 

It is realized that the idea here outlined, if followed 
to its logical conclusion, is contrary to many current 
beliefs regarding the continued sinking of a basin bv 



constant additions of load and its final collapse from 
the same cause. It is believed that the available evi- 
dence does not favor such a concept but indicates that 
basin/ sinking and interbasin upwarp was a long con- 
tinued process due to forces which originated outside of 
the local province of deposition and erosion. The final 
collapse was not due to deep basin filling but to one of 
many strong orogenie pulses which affected the conti- 
nental margin. The localization of the major overturn- 
ing and thrusting toward the basins was a result of 
basin-filling and marginal thinning but the compressive 
forces which were the cause of the orogeny were not 
brought into play by local erosion and deposition. 

The effect of the late Pliocene and mid-Pleistocene 
orogenies naturally differed with the type of bedrock 
undergoing deformation. The regions underlain at 
comparatively shallow depths by crystalline rocks, or 
those where the crystalline rocks were exposed, yielded 
by faulting, while those underlain by thick sedimentary 
prisms yielded by folding and ultimately by thrusting. 
However, as pointed out previously, it is difficult to 
draw the line between thin- and thick-blanketed areas. 
Regions with a crystalline basement at present depths 
of 8,000 or 9,000 feet (known from deep wells) yielded 
in a manner very similar to those underlain by at least 
twice this thickness of sediments. 

Under the strong Plio-Pleistocene compressive forces 
the areas underlain by thick prisms of sediments first 
began to rise along the pre-existing upwarps. These 
were rapidly folded, most strongly along regions of mar- 
ginal thinning which corresponded to the margins of 
the upwarps which began to form in the early Miocene 
and were accentuated in the upper Miocene. These 
areas first rose by folding which increased until the 
marginal folds were overturned away from the rising 
ridges toward the deeper basins. Finally the stretched 
limbs of the overturned folds yielded by thrusting, and 
as the ranges rose they were thrust outward over the 
adjacent basins. Thus the areas between the original 
downwarps rose as ridges whose flanks were thrust out- 
ward over the thick sediments of the basins. Along 
the present ranges, formed in thick, yielding sedimen- 
tary prisms, the thrusts dip inward toward the ranges 
and, except where guided by pre-existing faults, repre- 
sent the stretched and broken limbs of anticlines devel- 
oped on the thinning edges of Miocene and Pliocene 
basins of deposition. 

In the central Coast Ranges the central belt of crys- 
talline rock transmitted the forces to the more easterly 
belt of thick sediments, and these were folded in the 
same way as those to the west. 

On the accompanying cross-sections these marginal 
folds, along which the ranges rose, are shown as steepen- 
ing downward and hence with a basinward concavity. 
It is admitted that the actual visible evidence for this 
can be seen only occasionally. In following certain 
thrusts from deep canyons to ridges there is, in some 
cases, an actual decrease in angle. Also the thrusts 
developed within the ranges are always steeper than the 
outer marginal thrusts, except where there have been 
complications introduced by previous structures. It is 
believed that there are adequate grounds, both observa- 
tional and inferential, for the downward steepening of 
the thrust along which the ranges rose. These marginal 



158 



Geologic History and Structure 



[Chap. V 



thrusts were the result of the breaking of overturned 
folds and are essentially parallel with the fold axes; it 
is hardly possible that the axial planes of the folds are 
concave toward the centers of the ranges. The most 
perfect examples of the formation of ranges by upbow- 
ing, folding, and rising along outward-dipping thrusts 
are the central and southern Santa Lucia Range and the 
central and northern parts of the Castle Mountain 
Range. The northern part of the Santa Lucia Range 
exhibits the same type of structure but it is compound 
and consists of at least two units. It is further compli- 
cated by the presence of crystalline basement rocks at 
the surface. 

Although the ranges are practically always bordered 
by marginal thrusts the individual faults rarely can be 
traced for more than 20 or 25 miles. As a thrust dies 
out its place is taken by one or more en echelon faidts. 
Frequently the thrusts steepen as they die out in a 
bundle of folds. Occasionally the larger thrusts die 
out by branching, as the great Oceanic thrust zone on 
the west side of the Santa Lucia Range. This thrust, 
along which Franciscan is moved westward over the 
Miocene, branches at San Simeon Creek and the branches 
gradually diverge and die out; each branch can be 
traced by discontinuous belts of overturned Miocene 
sediments and volcanics overriden by Franciscan. 

The angle of inclination of the thrusts varies from 
less than 20 to over 80 degrees. The outer marginal 
thrusts average between 40 and 50 degrees; the faults 
within the ranges are somewhat steeper and usually 
increase in angle as the center is approached. The beds 
on the under sides of the thrusts are practically always 
overturned through stratigraphic thicknesses of less 
than 100 to more than 2,000 feet. 

In addition to the thrusts there are transverse faults, 
some of which cut almost completely across the range. 
These are especially numerous in the Santa Luc-ia Range, 
where they have had a marked effect on the amount of 
uplift attained. In the southern part of the Adelaida 
quadrangle the southerly decrease in the elevation of 
the range is definitely related to a series of transverse 
faults, each having the down-throw on the south. 

Some of the individual ranges of the Coast Ranges 
are similar to mountains that have been described by 
Continental and American geologists, but they are smaller 
than most of the examples that have been cited. The 
Castle Mountain Range, with its overturned marginal 
folds and thrusts and its central synclinal area, modi- 
fied by minor warps and faults, is very similar to the 
larger picture given by Kober of "Randketten" riding 
out over bordering rigid plates, and separated by 
gently folded, essentially synclinal "Zwischengebirgen". 
Here, however, the likeness ends, as the explanations 
given by Kober and the writer differ fundamentally. 
The Santa Lucia Range is much more complex and, 
while essentially due to the same causes as the Castle 
Mountain Range, differs from it in many respects. In 
fact the Santa Lucia Range is compound north of the 
latitude of Bradley and consists of at least two imper- 
fectly developed units bordered by marginal faults, a 
condition due to the development of basins on a crystal- 
line basement, much of which stood above sea level dur- 
ing the Miocene. The type of ranges developed in the 
Coast Ranges is not due to the crushing of a deep geo- 



syncline between two rigid plates, as are some of the 
examples cited by Kober and others, but are features 
which developed between comparatively small basins. 

Some of the faults which were formed during the 
Eocene as profound normal faults became active during 
the Plio-Pleistocene diastrophisms as thrusts. This 
was only natural since they were lines of weakness, 
usually between two very different types of rocks. On 
some of these there was a definite reversal of movement 
and the former downthrown side was thrust upward 
and over the former upthrown block. Concrete exam- 
ples of this reversal of movement are to be found in 
the San Marcos fault and in some places along the 
eastern side of the Gabilan mesa; both of these faults 
have been described previously and both are shown on 
some of the accompanying cross-sections. The writer 
does not believe that such movement along older faults 
can be considered as a renewal of growth on that par- 
ticular fault. The types of forces causing the two 
movements were very different and ffiey were separated 
by a long interval of time during which the fault was 
inactive and was covered by a great thickness of sedi- 
ments. The older faults, usually because they were 
between such diverse rock types as granodiorite and 
sediments, merely localized the later movements. Other 
old faults which are known to have moved during the 
severe Plio-Pleistocene diastrophisms were the Las 
Tables, Waltham Canyon, and Pescadero. Probably 
many older faults again broke, but most of the thrusts 
appear to have been newly formed features. It is some- 
times possible to distinguish a newly formed thrust 
from breaking along an older line by the type of move- 
ment which took place. In general the newly formed 
thrust is a cleaner, more continuous break that can be 
related definitely to the breaking of an overturned fold. 
Movement along older lines sometimes has a tendency 
to be very complex, with a number of parallel lines of 
movement, or with a series of small discontinuous en 
echelon breaks. Furthermore, they may exhibit what 
appear to be very profound displacements which die out 
with great rapidity. Newly formed thrusts usually 
bear a closer relation to basin margins than movements 
along old faults, which may take place either within 
the range or within the basins. However these can only 
be considered as generalizations, as there are many 
exceptions. 

Many different opinions have been expressed as to 
the importance of the King City fault; some have held 
that it is one of the major features of central California 
and others have expressed doubt as to its existence. 
Although the evidence for a fault along the east side 
of the Sierra de Salinas is largely physiographic there 
is some direct evidence of its presence. Physiographic 
evidence for the King City fault is the steep, straight 
eastern front of the Sierra de Salinas which attains an 
elevation of over 3,800 feet above the Salinas Valley 
within 2 miles, and which is cut by sharp steep-walled, 
high-gradient canyons. Alluvial fans, formed at the 
mouths of these canyons, have coalesced into a continu- 
ous apron along the range front, burying practically 
all direct evidence of faulting. The streams causing 
the fans are consequent streams resulting from recent 
uplift. Deep water wells along this front have not 
encountered the crystalline rocks which make up the 



Central Coast Range s — T aliaferro 



159 



Sierra de Salinas at depths of as much as 1,300 feet 
below sea level. Wells along the east side of Salinas 
Valley, at the foot of the Gabilan Range, reach the 
t crystalline basement rocks at comparatively shallow 
depths and indicate that the Gabilan Range surface 
slopes gently westward beneath the Salinas Valley. 
Shear zones have been reported in the crystalline rocks 
along the east front of the Sierra de Salinas; these are 
parallel to the front and may represent movements along 
minor faults west of the King City fault. 

The Sierra de Salinas and its wide alluvial apron 
end just north of Arroyo Seco, and a mile east of 
Paraiso Springs a fault emerges from beneath the allu- 
vial apron. This trends due south for about 2 miles and 
then turns to the southeast, crossing both Arroyo Seco 
and Reliz Canyon and dying out in Miocene sediments. 
This is a high-angle thrust fault, dipping southwest 
into the range, between Miocene shales on the west and 
Santa Margarita and Paso Robles on the east. This is 
thought to be a branch of the King City fault, although 
it may be its southern end, as the Salinas Valley is no 
longer bordered by a steep front flanked by an alluvial 
apron. The King City fault may extend to the south- 
east along the edge of the valley either as a fault in 
the bedrock or as a zone of sharp flexing in the Tertiary 
sediments. In the King City, Priest Valley, and Brad- 
ley quadrangles there is a zone of steepening and occa- 
sional overturning toward the northeast along the hill 
front which may represent the southeastern continua- 
tion of the King City zone. Even this dies out a short 
distance south of San Ardo. There is no surface evi- 
dence of any kind that the King City fault extends 
even as far south as King City. However there is good 
evidence that it has a length of about 25 miles, which 
is as long or longer than most of the marginal faults 
of the Santa Lucia Range. It is not a major feature 
of central California but merely one of the system of 
faults developed in the late Pliocene and mid-Pleisto- 
cene. The coarse detritus of crystalline rocks and the 
abundant Miocene shale pebbles in the Paso Robles in 
the vicinity indicate that there was movement in the 
late Pliocene, and the high dips in the Paso Robles 
indicate renewed faulting in the mid-Pleistocene. 
Movement may have taken place at an earlier date, but 
of this there is no evidence. The present elevation of 
the Sierra de Salinas is only in part due to the fault- 
ing, as this range stood above sea level in both the 
Miocene and Pliocene. 

Although greatly influenced by earlier movements 
the present major structural and topographic features 
of the central Coast Ranges were developed by the late 
Pliocene and mid-Pleistocene diastrophisms. The move- 
ments since the mid-Pleistocene have been important 
but they have not obliterated or greatly modified the 
features established at the close of the mid-Pleistocene 
orogeny. Great slides resulted from the mid-Pleisto- 
cene uplift of the ranges and these have somewhat 
obscured the marginal thrusts; but subsequent erosion 
has dissected these early slides and the Plio-Pleistocene 
structures are exposed in the gullies and canyons. 

Although the Plio-Pleistocene diastrophisms acted 
on a somewhat heterogeneous area of strongly contrasted 
types of bedrock, the writer can see nothing that is not 
orderly and comparatively simple either in the Miocene 



and Pliocene events which preceded and strongly influ- 
enced the localization of these movements or in the dias- 
trophisms and their results. There is nothing strange 
or abnormal in the filling of basins which sank by simple 
downwarping accompanied by the gentle upwarping of 
interbasin areas and a thinning of the sediments across 
them. The compressive forces causing warping reached 
minor peaks in the upper Miocene and Pliocene and 
caused local marginal unconformities through the uplift 
of the interbasin areas, but with continuous deposition 
in the sinking basins. These comparatively minor and 
easily understood complications, together with struc- 
tures inherited from earlier diastrophisms and great 
differences in rigidity of bedrock resulted in many 
apparent complexities when the entire region was sub- 
jected to the strong late Pliocene and mid-Pleistocene 
diastrophisms. Other minor complexities arose from 
the presence of islands of rigid crystalline rocks in the 
Miocene and Pliocene seas, against which the sediments 
were crushed, and which often caused great divergences 
in fold trends. A concrete example of this type of 
complexity is found in the Arroyo Seco region, north- 
west of King City, where the folds in the Miocene and 
Pliocene sediments curve from their normal northwest 
trend to east-west and even east-northeast because of the 
buttressing effect of the crystalline rocks of the Sierra 
de Salinas, toward which the sediments thin, and which 
stood as an island in the Miocene sea. When we con- 
sider the many possible causes of complexities it is sur- 
prising that the pattern is not even more irregular. 
Since there is a reasonably logical sequence of events 
and since it is possible to observe comparatively orderly 
progression from cause to effect, the writer can see no 
reason for calling the Coast Ranges a heterogeneous 
mobile belt. Heterogeneities exist, but when understood 
they become part of a related series of events. 

SAN ANDREAS RIFT 

Perhaps the most important, and certainly the most 
discussed and widely known structural feature of cen- 
tral California developed since the mid-Pleistocene orog- 
eny is the San Andreas rift, regarding which so many 
conflicting statements have been made. The writer is 
well aware that the conclusions presented here will be 
(contrary to many of the current views regarding this 
feature. These conclusions, however, are not based on 
hypothetical reasoning, on a preconceived idea, or on 
any of the conflicting statements that have been made, 
but have developed gradually as field observations have 
accumulated during many years mapping over a wide 
belt from the Pacific Ocean to the San Joaquin Valley. 
The statements made at this time apply only to that 
part of the San Andreas north of Parkfield, but it is 
believed that ultimately they may be extended to the 
zone as a whole. 

The chief difficulty in the way of a study and inter- 
pretation of the San Andreas rift is the disentanglement 
of this line of movement from earlier faults. It is 
probable that many of the misconceptions that have 
arisen have been due to a confusion of the San Andreas 
with earlier movements of a very different type. It is 
impossible to discuss and interpret the San Andreas line 
of movement without considering the major structural 
features of the central Coast Ranges as a whole. As has 
been stated a number of times previously, a profound 



160 



Geologic History and Structure 



[Chap. V 



normal fault developed in the early Eocene along the 
eastern side of the Gabilan mesa, by which the south- 
western side was elevated with respect to the northeast- 
ern side and stripped of its cover of Mesozoic rocks. 
Southwest of this fault is the crystalline basement com- 
plex and northeast is a thick prism of sediments. Many 
of the inequalities of relief caused by this fault were 
obliterated by erosion prior to the middle Miocene, when 
it was again partially flooded and sediments deposited 
across it. It did not act as a barrier to either the 
upper Miocene or Pliocene seas, and there is no sign of 
any general movement along it until the late Pleisto- 
cene. This has been referred to previously as the ances- 
tral San Andreas, chiefly for brevity of reference rather 
than as an implication that it was related in origin 
to the present San Andreas. When the forces which 
caused the formation of the San Andreas rift came into 
being this important but long inactive line was in exist- 
ence, and it probably aided in localizing a new type of 
movement. In the more than 50 miles of the San 
Andreas fault that haA'e been followed and mapped by 
the writer, the San Andreas fault is close to but rarely 
exactly coincident with this earlier line. The earlier 
line is always the boundary between crystalline base- 
ment complex and Mesozoic sediments (Franciscan, 
Knoxville, Shasta, and Upper Crustaceous). The San 
Andreas fault however is rarely the boundary between 
these two very diverse types, but usually is either wholly 
within crystalline rocks or Mesozoic rocks, except where 
it cuts through either Miocene, Pliocene, or Pleistocene 
sediments. It might be argued that it forms the bound- 
ary between crystalline basement and sediments in 
depth, but when we consider the eastward dip of the 
Eocene fault and the fact that the San Andreas is often 
west of the crystalline boundary, this is hardly likely. 
As has been stated previously the present major struc- 
tural and topographic features were formed by the 
Plio-Pleistocene diastrophism. The late mid-Pleistocene 
thrusts and all the features of overturning and the posi- 
tive evidence of uplift associated with them are cut by 
the San Andreas and actually may be traced across the 
latter; even the early slides are traversed by the San 
Andreas. Nearly everywhere along the San Andreas 
there is abundant physiographic evidence of recent fault- 
ing, such as true sag ponds and offset ridge and drain- 
age lines. However, along the earlier mid-Pleistocene 
faults there is no similar direct physiographic evidence 
of faulting. Late as they are, erosion has obliterated 
any such features originally present. Of course the 
ranges themselves are visible evidence of their effect, 
but of such direct physiographic evidence as exists along 
so much of the San Andreas rift there is no trace. 

As a concrete example may be mentioned a thrust 
which has brought Franciscan and Cretaceous rocks 
above overturned Miocene and Pliocene sediments in an 
eastward-dipping fault which is the main inward-dip- 
ping thrust on the west flank of Castle Mountain Range. 
This thrust lies nearly 3 miles east of the San Andreas 
fault in the latitude of Parkfield, from which point it 
may be traced northwestward as a continuous zone of 
thrusting and overturning. About 12 miles northwest 
of Parkfield it becomes entangled with the San Andreas 
zone and, for a distance of about 3 or 4 miles the two 
can not be separated because of the very acute angle of 
intersection. However, 15 to 16 miles north of Park- 



field it emerges, with all its characteristics of uplift, 
thrusting, and overturning on the opposite, or west, side 
of the San Andreas zone, and may be traced northward 
for 15 miles before it is lost. To the southeast of the 
intersection the San Andreas lies wholly within the crys- 
talline basement and its Tertiary cover, and to the north- 
west wholly within Franciscan, Knoxville, and Shasta 
beds. There is abundant undestroyed evidence of recent 
movement everywhere along the San Andreas, but none 
along the thrust, except where the two coincide. 

The opposite, or southwestward-dipping zone of 
thrusting which marks the eastern margin of Castle 
Mountain Range lies 12 miles east of the San Andreas 
in the latitude of Castle Mountain. This, and identical 
en echelon zones having the same effect, continue north- 
westward for 40 miles before being cut by the San 
Andreas. Thus, the more recent San Andreas move- 
ment cuts across the older Plio-Pleistocene structures 
at an angle. Many of these earlier thrusts have been 
regarded as branches of the San Andreas but they are 
earlier features formed by a very different type of move- 
ment and may be traced across the later line. Every- 
where along the earlier thrusts are found the usual 
features of broken overturned folds, of uplift on one 
side and the overturning of beds on the other, features 
which are everywhere characteristic of the margins of 
the uplifted ranges. These effects are never found 
along the San Andreas except where it coincides with 
the thrusts for short distances. 

Mustang Ridge forms the northwestern end of Castle 
Mountain Range and was formed at the same time and 
in the same manner, that is, in the mid-Pleistocene by 
outward thrusting on both sides. The San Andreas 
zone enters the southwestern corner of Mustang Ridge, 
crosses the ridge and emerges on the east side and con- 
tinues northwestward along the east side of Bitterwater 
Valley, having completely cut across a definite topo- 
graphic and structural unit. Throughout its course 
across Mustang Ridge, the San Andreas rift lies wholly 
within Franciscan, Knoxville, and Shasta, and is nearly 
everywhere, whether on the flanks or crest of the ridge, 
marked by sag ponds, trenches, and other familiar 
physiographic features indicating recent movement. 

The Pilarcitos thrust, which cuts diagonally across 
the southwestern part of the San Mateo quadrangle and 
continues to the southeast across the Santa Cruz quad- 
rangle, appears to be another example of the truncation 
of a late Pliocene fault by the San Andreas. At its 
northwestern end the Pilarcitos thrust is almost 4 miles 
southwest of the San Andreas ; to the southeast it grad- 
ually approaches and finally crosses the San Andreas in 
the Santa Cruz quadrangle. The region to the south- 
east has not been mapped and its continuation in that 
direction is not known. The Pilarcitos thrust is not a 
branch of the San Andreas as has been suggested but is 
a fault formed first in the Eocene, after the deposition 
of the Paleocene and before the deposition of the 
Vaqueros. It is in fact the same Eocene zone of normal 
faulting which marks the northeast side of the Gabilan 
mesa to the southeast. This became active again in the 
late Pliocene, and possibly in the mid-Pleistocene, and 
experienced a reversal of movement, the Franciscan 
being thrust to the southwest over Cretaceous and Paleo- 
cene and the basement complex (here largely granodi- 



Central Coast Range s — T aliaferro 



161 



orite) on which they rest. Kober was correct in stating 
that the Pilarcitos thrust is not a subordinate feature, 
but his statement that it is an allochthonous nappe is 
entirely without any supporting evidence. 

The San Andreas has produced no important struc- 
tural modification of features formed by the Plio- 
Pleistocene diastrophism throughout its course from 
Parkfield to the Pacific Ocean. All of the thrusting 
and overturning in the vicinity of the San Andreas are 
definitely related to similar structures which resulted 
from strong compression in the late Pliocene and mid- 
Pleistocene and which produced the dominant type of 
structure and topography from the Pacific Ocean to the 
San Joaquin Valley ; these are universal in the Coast 
Ranges and are not features peculiar to the San Andreas 
zone. Statements that the San Andreas zone is several 
miles in width are the result of failure to separate the 
effects of earlier orogenies from later movement. Unless 
such a distinction is made the San Andreas becomes a 
zone of fantastic width. 

The compressive forces which resulted in the late 
Pliocene and mid-Pleistocene diastrophisms not only 
produced characteristic structural features that are cut 
by the San Andreas, but the present major topographic 
features as well. These also are cut indiscriminately 
by the San Andreas, which, north of Parkfield at least, 
cuts across both ridges and valleys. Rift features, 
which as a rule can be readily followed, are not con- 
fined either to ridges or valleys but cross both. 

The greatest apparent complexity and width of the 
San Andreas zone known to the writer are shown on 
cross-sections II and III on Plate II. Most of these 
features antedate the San Andreas movements and are 
the result of the effect of pre-existing topography and 
the Plio-Pleistocene diastrophisms. In this region, 
largely in the northeastern part of the San Miguel 
quadrangle and extending into the Priest Valley quad- 
rangle, there were islands of ancient crystalline rocks 
in the upper Miocene and lower Pliocene sea. Both the 
upper Miocene and lower Pliocene in this region con- 
sist of coarse arkose and breccias deposited about the 
islands which may have been completely covered during 
the Pliocene. The soft sediments were faulted and 
crushed against the rigid crystalline rocks, which had 
a very irregular surface, and very complex structures 
resulted. It has been necessary to omit many of the 
minor details from the cross-sections because of the 
scale. The apparent width and complexity in this 
region are the result of the Plio-Pleistocene diastro- 
phisms acting on unconsolidated sediments resting on 
a very irregular surface rather than movement along 
the San Andreas rift. 

That there has been horizontal movement along the 
San Andreas rift is clearly shown by offsetting of ridge 
and drainage lines as well as by the visible movement 
in 1906. The same type of movement has taken place 



along the Hayward fault, which may be a branch of the 
San Andreas, although a definite connection has never 
been established. The writer is aware that there are 
many who believe that great horizontal movement has 
taken place along the San Andreas rift, movements 
measurable in miles, or even scores of miles. Shifts 
of this magnitude may have occurred south of the region 
studied by the writer but along that part of the rift 
north of Parkfield there is no evidence for, and much 
against, great horizontal movement. Thus far it has 
been impossible to obtain definite evidence of the exact 
amount of movement because of the rather acute angle 
of intersection of the rift and the structural and topo- 
graphic features formed by the Plio-Pleistocene diastro- 
phisms, but there is reasonable evidence that the 
horizontal movement has been less than a mile; had a 
shift of greater magnitude taken place the offsetting 
of mid-Pleistocene structural and topographic features 
would be clearly shown. The maximum offsetting of 
drainage lines, caused by repeated movements along 
parallel breaks, is less than 3,000 feet. 

As a result of field evidence accumulated over a 
long period of time and from a large area in the central 
Coast Ranges, the following conclusions regarding the 
San Andreas fault have been reached : 

1) The San Andreas zone roughly coincides with a 
zone of profound Eocene faulting which marks 
the boundary between the ancient crystalline 
basement and Mesozoic rocks. However, the two 
do not always agree, and the later zone may be 
wholly within either the crystalline basement or 
the Mesozoic rocks. 

2) The movement has been chiefly horizontal but 
in that part of the rift north of Parkfield the 
horizontal shift has been small, and has not been 
greater than 1 mile and probably even less. 

3) The horizontal shifting along the San Andreas 
zone is a very late feature, as it cuts across struc- 
tures and topography developed in the late Plio- 
cene and mid-Pleistocene. Although a major 
structural feature, the effects produced by all of 
the late Pleistocene and Recent movements along 
it have not been comparable with those which 
resulted from the Plio-Pleistocene diastrophisms. 
It has produced no important modification of 
either the structures or topography formed by 
these diastrophisms. 

4) The supposed branches or "barbs" are actually 
earlier faults which were formed by a very dif- 
ferent type of movement, and which may be 
traced across the San Andreas. No important 
faults branch off from the San Andreas north of 
Parkfield, with the possible exception of the Hay- 
ward; even in this case a direct connection 
between the two has not been established. 



162 



G E O L O O I C II I S T R Y AND STRUCTURE 



[Chap. V 



EXPLANATION OF GEOLOGIC STRUCTURE SECTIONS— PLATE II 



Ten structure sections of the central Coast Ranges, 
extending from the Pacific Ocean to the San Joaquin 
Valley have been prepared. These range from 50 to 86 
miles in length and are believed to give a fairly accurate 
picture of the structure of the central Coast Ranges over 
a distance of 170 miles, from San Luis Obispo County 
on the south to Mount Diablo on the north. All but one 
of these are continuous sections but because of lack of 
information in critical areas it was necessary to break 
section VIII into two disconnected parts. Sections I to 
VI inclusive and section VIII B are based on field work 
done by the writer, except for the extreme northeastern 
ends of sections IV, V, and VI which are taken from 
the literature. The remaining sections are based on pub- 
lished material and on unpublished theses of graduate 
students of the University of California and Stanford 
University ; the source of the information is given below 
each section. Occasionally the sections have been slightly 
changed from the originals, the modifications being based 
on actual field observations made by the writer. 

Section VIII B is obviously incomplete and is based 
on reconnaissance work only. The writer expects to 
publish more complete and accurate sections, in this and 
other localities, in the future. Incomplete and inaccu- 
rate as is section VIII B, especially immediately east of 
the Santa Clara Valley, it has been included to show the 
great thickness of Knoxville (Upper Jurassic) and 
Shasta (Lower Cretaceous) sediments, folded into a 
syncline, and to contrast the conditions on the two sides 
of the Diablo Range in this region. 

Sections I to VI inclusive are not built up from trav- 
erses but are based on detailed mapping over a large 
area (with the exception of that part of section VI which 
crosses the King City quadrangle) and are thus believed 
to be more accurate than sections based on traverses 
alone. Subsurface relations which might be considered 
obscure from the sections alone would be clear if a geo- 
logical map were available. Because of the scale on 
which the sections are published it has been necessary to 
omit much detail in areas of complex structure. Since 
the sections are in black and white it has been impossible 
to show lithologic variations within any single unit : this 
is unfortunate as such lithologic variations often indicate 
shore lines and the source of the sediments. More than 
40 units have been recognized and mapped in the field ; 
these have been condensed to 20 units on the sections. 

Since the sections have been carried to depths of 
7,000 to 9,000 feet below sea level it is obvious that a 
large element of interpretation has entered into their 



construction. However, a number of deep wells have 
materially aided in the construction of several of the 
sections; this is especially true of the Gabilan mesa 
where deep wells have given valuable information regard- 
ing the depth to the crystalline basement. 

The structure of the Franciscan has been generalized 
but in the majority of the sections the positions of the 
major folds are accurately located. Minor crumplings 
and minor igneous bodies in the Franciscan necessarily 
have been omitted. 

The interpretation given to the serpentine body in 
the heart of the Coalinga anticline in sections V and VI 
is new and may be startling. Obviously, direct observa- 
tion along the line of section is impossible but from 
indirect evidence, such as folded leaves of Franciscan 
sediments along the crest of the fold (one of which is 
shown in section VI) and many parallel leaves about 
the margins, it is believed this is a folded sill which 
swells into an irregular laccolith in the Coalinga anti- 
cline and which thins westward toward Laguna Moun- 
tain and Hepsidam Peak. The bottom of the thin 
westward continuation may be seen south of the line of 
section VI. Both the bottoms and tops of the folded 
serpentine sills shown in the Santa Lucia Ranges and in 
Table Mountain may be seen in many places. 

The field evidence for the inward dipping thrusts 
along the margins of the Santa Lucia Range and Castle 
Mountain is clear and convincing. The positions and 
inclinations of these thrust planes are based on surface 
observations, checked in two eases by subsurface infor- 
mation from mines. 

The westward dipping thrust on the east side of the 
Diablo Range as shown on sections VI to X inclusive, 
has never been mentioned in the literature. In fact 
much of the evidence for this thrust has been obtained 
since the accompanying paper was written. It is espe- 
cially impressive in the New Idria mine (section VI) 
where the average dip in a vertical distance of over 1,500 
feet is 54 degrees, and in the vicinity of Ortigalita Creek 
(section VII) where the dip varies from less than 30 to 
45 degrees in a vertical distance of nearly 1,000 feet. 
This thrust, which is definitely late Pliocene and was 
not active in the mid-Pleistocene, was responsible for a 
large part of the uplift of the Diablo Range. 

The sections illustrate the description of the structure 
given in the accompanying paper. They also clearly 
indicate the important orogenies mentioned. It is 
regretted that space does not permit a detailed discus- 
sion of each section. 



1 



sooo 

2300 

Sea Level- 



IX 



sooo 

2M0- 



Sea Level- ^ 



hua 



S000-- ' 



S.I 



J 



Central Coast Range s — T aliaferro 



163 







Fig 59A A well exposed anticline in the northern Coast Ranges, with an oil derrick on its crest. 
Looking northwest toward Point Arena. Photograph by Olaf P. Jenkins. 




Fig. OSB. A typical view in the central Coast Ranges, showing landslide topography of the Franciscan 
in the foreground. Looking south across Teachtree Valley. Photograph by Olaf P. Jenkins. 



Chapter VI 

Paleontology and Stratigraphy 



CONTENTS OF CHAPTER VI 

Page 
Characteristic Fossils of California, By G. Dallas Hanna and Leo George Hertlein 165 

Descriptions of Foraminifera, By C. C. Church 182 

Synopsis of the Later Mesozoic in California, By Frank M. Anderson 183 

Notes on California Tertiary Correlation, By Bruce L. Clark 187 

Eocene Foraminiferal Correlations in California, By Boris Laiming 193 

Sequence of Oligocene Formations of California, By Lesh C. Forrest 199 

Correlation Chart of the Miocene of California, By Robert M. Kleinpell; Introduction By William D. 

Kleinpell 200 

Pliocene Correlation Chart, By U. S. Grant IV and Leo George Hertlein 201 

The Pleistocene in California, By J. E. Eaton 203 



CHARACTERISTIC FOSSILS OF CALIFORNIA* 

By O. Dallas Hanna** and Leo George Hertlein*** 



OUTLINE OF REPORT 

Page 

Introduction 165 

Acknowledgments 1(!."> 

General features 165 

Paleozoic, Trias.sic, and Jurassic fossils 166 

Cretaceous and Upper Jurassic fossils 168 

Eocene, Oligocene, and Miocene fossils 168 

Miocene fossils 172 

Miocene, Pliocene, and Pleistocene fossils 174 

Pliocene fossils 176 

Diatoms (Cretaceous to Recent) 178 

Foraminifera I Cretaceous to Pliocene) 178 



INTRODUCTION 

Because of the special interest in the sedimentary 
formations of Tertiary age, in relation to the explora- 
tion for petroleum in California, most of the fossil speci- 
mens illustrated in the following eight plates have been 
selected from beds of that geologic period. One plate 
of Cretaceous and one plate of pre-Cretaceous fossils, 
however, have also been included. 

In choosing the fossils for these plates, an endeavor 
has been made to select forms which are usually com- 
mon, and which are confined to narrow stratigraphic 
ranges. Unfortunately, however, space is limited, and 
it has been impossible to include all of even the most 
familiar species. It is desirable here to call attention 
to a recent publication that contains marker fossils, 
"California Fossils for the Field Geologist", bv H. G. 
Schenck and A. M. Keen (40). 

ACKNOWLEDGMENTS 

The specimens from the Cretaceous have been selected 
by Dr. F. M. Anderson. Those of the pre-Cretaceous 
were furnished bv Dr. S. W. Muller of the Department 
of Geology of Stanford University. Mr. C. C. Church 
has assisted with the Foraminifera. Messrs. C. M. Car- 
son and J. B. Stevens cooperated in numerous ways 
particularly in the assembling of specimens. These 
contributors, together with Dr. H. G. Schenck of the 
Department of Geology at Stanford University, have 
helped with the determination of species, and to all of 
them we extend our thanks. 

Photographs of the specimens (except the diatoms') 
were made by Frank L. Rogers ; typing was done by 
Alta Holton, as a part of work accomplished by Federal 
Works Progress Administration, Project No. 10906. 

All the specimens illustrated, except those furnished 
by Dr. Muller and Dr. Schenck, are preserved in the 
series of type specimens of the Department of Paleont- 
ology, California Academy of Sciences. The pre-Cre- 
taceous specimens illustrated are in the Department of 
Geology at Stanford University. Casts of these are 
in the type series of the California Academy of Sciences. 



• Manuscript submitted for publication December 2, ir*40. 
'•Curator. Department of Paleontology, California Academy of 
Sciences, San Francisco, California. 

•••Assistant Curator, Department of Paleontology, California 
Academy of Sciences, San Francisco, California. 



GENERAL FEATURES 

A brief explanation of the significance of fossils may 
be pertinent for those who are not familiar with the 
nomenclature and occurrence. Certain genera have a 
very restricted range, for example, the sand dollar, 
A at rod apsis, occurs in the upper Miocene and lower 
Pliocene, and. in the very southern part of the State and 
in Lower California, in the middle Pliocene. The spe- 
cies of the genus, however, are restricted to certain 
narrow stratigraphic zones; Astrodapsis tumidus, for 
instance, occurs only in a zone of that name in the upper 
Miocene. Such a zone is extremely useful for field map- 
ping of geologic formations. 

The ideal index fossil is one which is easily identified 
and which occurs abundantly over wide geographic 
extent but in a limited stratigraphic range. Some peri- 
ods are characterized by certain classes or genera. For 
example, ammonites are not known to occur later than 
the Cretaceous. The same is true of Inoceramus which 
can often be recognized in well cores by fragments of the 
shell which are composed of layers of prisms. In cer- 
tain genera or species, characteristic ornamentation of 
fossils can be used by field geologists. For instance, 
species of Aucella with strong radial striae ornamenting 
the shell are usually upper Jurassic in age, while those 
of the Lower Cretaceous are usually without such radial 
striae or if these are present they are much less conspicu- 
ous. Large species of Vencricardia occur in the Eocene 
but those with nearly obsolete ribs or nearly smooth 
shells such as Venericardia inncnsis are characteristic 
of the middle Eocene. The genus Tejonia occurs only 
in the middle and upper Eocene. With the exception 
of a couple of species, giant thick-shelled pectens occur 
from Miocene to Recent. The same appears to be true 
of Dosinia. Giant species of Tvrritella are common 
in the lower and especially in the middle Miocene of 
California, and giant oysters occur commonly in the 
Miocene, and lower Pliocene. Specimens from the upper 
Miocene are reported to attain a length of 18 inches. 
Strongly plicated oysters occur in the lower Miocene 
and commonly in the middle and upper Pliocene where 
Ostrca v expert ina occurs. Dendraster, the genus to 
which the common living sand dollar belongs, is known 
only from Pliocene to Recent. 

Recent species are unknown in the Eocene of Cali- 
fornia, but beginning with the Oligocene, Recent forms 
appear. In the lower and middle Miocene about 20 
species have been cited as identical with Recent species 
and nearly a dozen others have been cited questionably 
as identical with Recent forms while many others are 
closely related. The number increases in the upper Mio- 
cene, while in the Pliocene at least a hundred Recent 
species appear, and in the late Pleistocene about f)5 per- 
cent of the species are to be found at the present time in 
waters of the adjacent regions. 

The climatic significance of the Tertiary faunas of 
California is interesting and important. This feature 
has been ably discussed by J, P. Smith (19) in his classic 
work on this subject. 



166 



Paleontology and Stratigraphy 



[Chap. VI 



A gradual cooling of the temperature is indicated by 
the Tertiary marine faunas. This becomes very pro- 
nounced in the late Pliocene and early Pleistocene but 
then is followed by decidedly warmer temperature in the 
upper Pleistocene. This is well illustrated at San Pedro, 
California, where Pccten caurinus and Borcotroyhon 
stuarti, cool-water forms, occur in the lower Pleistocene, 
while in the upper Pleistocene of San Pedro and San 
Diego, such species as Dosinia ponderosa, Chione (jnidia 
and Pectcn vogdesi are an element of the fauna. These 
species now are not found living north of Cedros Island, 



Lower California. Following the Pleistocene a slight 
cooling of the climate occurred, resulting in the climate 
of today. 

Field geologists can encourage the progress of pale- 
ontological studies by making careful collections of 
specimens which together with exact locality data should 
be deposited in an institutional collection where the speci- 
mens may be studied and the results published. A useful 
volume on the technique used in the preparation of 
specimens is given by Camp and Hanna (37). 



PALEOZOIC, TRIASSIC, AND JURASSIC FOSSILS 

Explanation of Figure 60 (1-25) 



Fig. 60-1. Weyla alata von Buch. Left valve. From south 
side of Mount Jura, Plumas County, California. W. Pratt, coll. 
Hardgrave sandstone, lower Jurassic. Length approximately 
59.3 mm ; height approximately 45.8 mm. 

Fio. 60-2. Halobia superba Mojsisovics. Left valve. From 
Brock Mountain, Shasta County, California. J. P. Smith, coll. 
Hosselkus limestone, upper Triassic. Length 36.2 mm ; height 
21.5 mm. 

FIG. 60-3. Pseudomonotis subcircularis Gahb. Right valve. 
From Indian Valley, Plumas County, California. J. P. Smith, 
coll. Noric stage, upper Triassic. Length approximately 51 mm ; 
height 42 mm. 

FIG. 60-4. Trachyceras leconiei Hyatt and Smith. Front 
view of specimen shown in figure 00-12. Upper Triassic. 

Fio. 60-5. Owenites koeneni Hyatt and Smith. Right side. 
From Loe. 894 (L. S. J. U.), Union Wash, Inyo Mountains, Inyo 
County, California. J. P. Smith, coll. Lower Triassic. Greatest 
diameter 31.4 mm. 

Fig. 60-6. Anoria lodensis Clark. Reproduction of figure 
given by J. F. Mason (35, p. 109, pi. 15, fig. 11). From Marble 
Mountains, San Bernardino County, California. Cadiz formation, 
Middle Cambrian. 

Fig. 60-7. Juvavites subinterruptus Mojsisovics. Left side. 
From Loe. 1705 (L. S. J. U.), Brock Mountain, Shasta County. 
California. J. P. Smith, coll. Hosselkus limestone, upper Trias- 
sic. Greatest diameter 41 mm. 

Fig. 60-8. Meekoceras newberryi Smith. Front view of 
specimen shown in figure 60-20. Lower Triassic. 

Fig. 60-9. Owenites koeneni Hyatt and Smith. Front view 
of specimen shown in figure 60-5. Lower Triassic. 

Fig. 60-10. Juvavites subinterruptus Mojsisovics. Front 
view of the specimen shown in figure 60-7. Upper Triassic. 

Fig. 60-11. Tropites subbullatus Hauer. Right side. From 
the same locality as the specimen shown in figure 60 7. Upper 
Triassic. Greatest diameter 29.5 mm. 

Fig. 60-12. Tracbycerus leconiei Hyatt and Smith. Left 
side. From the same locality as the specimen shown in figure 
60-7. Upper Triassic. Greatest diameter approximately 95 mm. 

Fig. 60-13. Psettdosageceras multilobatum Hyatt and Smith. 
Front view of specimen shown in figure 60-14. Lower Triassic. 

Fig. 60-14. Pseudosageceras multilobatum Hyatt and Smith. 
Left side. From the same locality as the specimen shown in 
figure 60-5. Lower Triassic. Greatest diameter approximately 
108.8 mm. 

Fig. 60-15. Aucella erringtoni Gabb. Right valve. From 
Texas Charlie's ranch 1 , miles east of Copperopolis, Calaveras 
County, California. J. I'. Smith, coll. Mariposa formation, upper 
Jurassic. Height, beak to base, approximately 29.2 mm ; length 
approximately 14 mm. Specimen somewhat distorted. 



The elongate shape and radial striae ornamenting the shell 
are characteristic of this species. 

Fig. 60-16. Parapopanoceras haugi Hyatt aim Smith. Right 
side. From Loe. 884 ( L. S. J. U.), Union Wash, Inyo Moun- 
tains, Inyo County, California. S. W. Muller, coll. Middle Trias- 
sic. Greatest diameter 21.8 mm. 

Fig. 60-17. Schizodus deparcus Walcott. From Baird, Shasta 
County, California. Baird shale, lower Carboniferous. Dimen- 
sions of right valve, length (incomplete) 32.8 mm; height (incom- 
plete) 27 mm. 

Fig. 60-18. Gigantella gigantea Martin. Posterior view of 
specimen shown in figure 60-19. Lower Carboniferous. 

Fig. 60-19. Gigantella gigantea Martin. Exterior view of 
dorsal valve. From the west bank of McCloud River, imme- 
diately above the Baird fishery, Shasta County, California. Baird 
formation, lower Carboniferous. Length (incomplete) 109.6 mm; 
height (incomplete) 67.6 mm; thickness approximately 29.5 mm. 

FlG. 60-20. Meekoceras newberryi Smith. Right side. From 
Union Wash, Inyo Mountains, Inyo County, California. J. P. 
Smith, coll. Lower Triassic. Greatest diameter 60.5 mm. 

Fig. 60-21. Griffithides nosoniensis Wheeler. Holotype 1 , No. 
778 (L. S. J. U.). From dark shale on the south side of the 
ridge south of Potter Creek, about 250 feet stratigraphically above 
the McCloud-Nosoni contact, elevation 1,800 feet, in NEJSWi 
See. 24, T. 34 N., R. 4 W., M. D., Redding quadrangle, Shasta 
County, California. S. W. Muller and H. E. Wheeler, colls. 
Lower Nosoni formation, Permian. Length (incomplete) approxi- 
mately 26.4 mm ; width approximately 18 mm. 

The dark areas on either side of the anterior half of the speci- 
men represent the cavities remaining after the dissolution of the 
marginal border and genal spines of the cephalon (Wheeler). 
(See Wheeler, H. E. 35, pp. 51-52, pi. 6, figs. 6 and 7.) 

Fig. 60-22. Tropites subbullatus Hauer. Back of specimen 
shown in figure 60-11. Upper Triassic. 

Fig. 60-23. Amoeboceras dubius Hyatt. Holotvpe, No. 1762 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loe. 556 (C. A. S.) 
(original No. 11953 Calif. State Mining Bureau), the Mariposa 
slates (middle Upper Jurassic) at Texas Charlie's ranch 1 , 6 miles 
north of Copperopolis, Calaveras County, California. Mariposa 
formation, upper Jurassic. Greatest diameter approximately 
20.8 mm. 

Fig. 60-24. Weyla alata von Buch. Right valve. From the 
same locality as the specimen shown in figure 60-1. Lower Juras- 
sic. Height (incomplete) approximately 46 mm. 

Fig. 60-25. Parapopanoceras haugi Hyatt and Smith. Front 
view of specimen shown in figure 60-16. Middle Triassic. 



1 Place shown on the Copperopolis quadrangle as "Texas 
Gulch," tributary to Angels Creek, is approximately G miles north- 
east of Copperopolis in Sees. 28 and 2'J, T. 2 N., R. 13 E., M. D., 
Calaveras County, California 

= Holotype : a single secimen (or fragment) upon which a 
species is based. (Frizzell, D. L. 33). 



C H A R A C TEBISTIC P O S S I h S- II A N N A A N I) II E BTI, E 1 N 



167 




FlG. 60 ( 1 to 25). Paleozoic, Triawsir, ami Jurassic fossils of California. 



168 



Paleontology and Stratigraphy 



CRETACEOUS AND UPPER JURASSIC FOSSILS 
Explanation of Figure 61 (1-22) 



[Chap. VI 






Fig. 61-1. Aucella crassa Pavlov. Hypotype, 3 No. 5970 
(Calif. Acad. Sri. Paleo. Type Coll.). From Loc. 27 (C. A. S.), 
on the north hank of Myrtle Creek, about 1| miles north of the 
town of Myrtle Creek, Douglas County, Oregon. Myrtle forma- 
tion, lower Cretaceous. Height 36.8 mm ; width .36.2 mm. 

This species occurs in the lower Cretaceous of California. 

Fig. 61-2. Aucella crassicolis Keyserling. Hypotype, No. 

5971 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1340 
(C. A. S.), half a mile south of ranch house, Wilcox Ranch, 5 
miles northeast of Paskenta, Tehama County, California. F. M. 
Anderson and G. D. Hanna, colls. Shasta series, lower Creta- 
ceous. Height 52.6 mm ; width 35.0 mm. 

Fig. 61-3. Aucella mosuuensis von Buch. Hypotype, No. 5967 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 28624 (C. A. S.), 
near Cushman's place, 1} miles southwest of Chrome, near north- 
east corner of SEi Sec. 31, T. 22 N., R. 6 W., M. P., Glenn 
County, California. J. A. Taff, F. M. Anderson, and C. M. Cross, 
colls. Knoxville, upper Jurassic. Altitude 20.0 mm ; width 
18.2 mm. 

Fig. 61-4. Aucella piochii Gabh. Hypotype, No. 5966 (Calif. 
Acad. Sci. Paleo. Type Coll.). From Loc. 155 (C. A. S.) Sees. 
34 and 35, T. 25 N., R. 7 W., 3± miles southwest of Lowry's 
house on Elder Creek drainage, Tehama County, California. F. M. 
Anderson, coll. Base of Knoxville series, upper Jurassic. Height 
26 mm ; width 16.4 mm. 

Fig. 61-5. Aucella piochii Gahh. Side view of specimen in 
figure 61-4. 

Fig. 61-6. Keocomitcs (Steneroceras) jenkinsi Anderson. Hy- 
potype, No. 7735 (Calif. Acad. Sci. Paleo. Type Coll.). From 
1,200 feet southeast of Burt's ranch house, McCarthy Creek, 
Tehama County, California. F. M. Anderson, coll. Fifteen hun- 
dred feet above base of Shasta series, lower Cretaceous. Greatest 
diameter approximately 36 mm. 

Fig. 61-7. Gabbioceras angulation Anderson. Hvpotvpe, No. 

5972 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1347 (C. 
A. S.), north of Roaring River, 5 miles south of Ono, California, 
on road to Millsap, Shasta County, California. F. M. Anderson, 
coll. Horsetown formation, lower Cretaceous. Greatest diameter 
36.9 mm. 

Fig. 61-8. Desmoceras haydeni Gabb. Hypotype, No. 5944 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1344 (C. A. S.), 
Horsetown, Shasta County, California. F. M. Anderson, coll. 
Lower Cretaceous. Greatest diameter 66.0 mm. 

Fig. 61-9. Metaplacenticeras pacificum J. P. Smith. Repro- 
duction (Anderson, F. M. 02, figure 162 on plate 8). From 
Arroyo del VallS, Alameda County, California. Upper Cretaceous. 
Diameter 20.5 mm. 

Fig. 61-10. Metaplacenticeras pacificum J. P. Smith. Repro- 
duction (Anderson, F. M. 02, figure 164 on plate S). From 
Henley, California. Upper Cretaceous. Diameter 47 mm. 

Fig. 61-11. Neocomites sp. cf. N. neocomiensis d'Orhigny. 
Hypotype, No. 5960 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Waltham Creek Valley, SWJ Sec. 17, T. 20 S., R. 13 E., M. D., 
north of the Coalinga-Priest Valley road, Priest Valley quadrangle, 
Fresno County, California. N. L. Taliaferro, coll. Lower Cre- 
taceous. Greatest diameter 21 mm. 



Fio. 61-12. Koxsmatia tehamaensis Anderson. Hypotype, 
(Univ. Calif.), and plasto-hypotype, No. 5956 (Calif. Acad. Sci. 
Paleo. Type Coll.). Dorsal view of specimen shown in figure 
61-16. From Loc. A2021 (Univ. Calif.), south fork of Elder 
Creek, Sec. 13, T. 24 N., R. 7 W., M. I)., Tehama County, Cali- 
fornia. R. Rist, coll. Lower Knoxville, upper Jurassic, Knox- 
ville series. Greatest diameter 47.2 mm. 

Fig. 61-13. Ftuhmortoniceras chicoensis Trask. Hypotype, 
No. 5052 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 27838 
(C. A. S.), from sandstone along southeast hank of Big Chico 
Creek 3.1 miles by road south of bridge at Mickey's ranch, or 3.6 
miles by road from Ten-Mile House on the Humboldt road east 
of the town of Chico, Butte County, California. J. A. Taff, 
G. D. Hanna, and C. M. Cross, colls. Type Chico formation, lower 
upper Cretaceous. Greatest diameter 58 mm. 

Fig. 61-14. Submortoniceras chicoensis Trask. Side view of 
the specimen shown in figure 61-13. 

Fig. 61-15. Dichotomites tehamaensis Anderson. Holotype, 
No. 5943 (Calif. Acad. Sci. Paleo. Type Coll.). From Wiicox 
ranch, 5 miles north of Paskenta, Tehama County, California. 
Lower Cretaceous. Greatest diameter 71.9 mm. 

Fig. 61-16. Kossmatia tehamaensis Anderson. Side view of 
specimen shown in figure 61-12. 

Fig. 61-17. Berriasella crassipticata Stanton. Hypotype, No. 
5958 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 2925 (C. 
A. S.), Paskenta beds on McCarthy Creek, Tehama County, Cali- 
fornia. R. Rist, coll. Lower Cretaceous. Greatest diameter 
31.6 mm. 

Fig. 61-18. Haniiticeras aequicostatus Gabb. Hypotype, No. 
5950 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1348 (C. 
A. S.), Alderson Gulch, on north fork of Cottonwood Creek, 2 miles 
south of Ono, Shasta County, California. F. M. Anderson and 
G. D. Hanna, colls. Horsetown beds, lower Cretaceous. Height 
58 mm. 

Fig. 61-19. Phylloeeras onoense Stanton. Hypotype, No. 
7736 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 153 (C. 
A. S.), head of Bee Creek, 3 miles south of Ono, on Shoup ranch, 
Shasta County, California. F. M. Anderson, coll. Horsetown 
beds, lower Cretaceous. Greatest diameter 114 mm. 

FIG. 61-20. Hibolites sp. Hypotype, No. 5060 (Calif. Acad. Sci. 
Paleo. Type Coll.). From Loc. 28607 (C. A. S.), lower beds of 
Knoxville series 3 miles north of old Knoxville (Reddington Mine) 
northern Napa County, California. N. L. Taliaferro, coll. Knox- 
ville, upper Jurassic. Length 47 mm. 

Fig. 61-21. Baculites chicoensis Trask. Hypotype, No. 5951 
(Calif. Acad. Sci. Paleo. Type Coll.). From the same locality as 
the specimen shown in figure 61-13. Type Chico formation, lower 
upper Cretaceous. Height 82.3 mm. 

Fig. 61-22. Bochianites sp. Hypotype, No. 5959 (Calif. 
Acad. Sci. Paleo. Type Coll.). From Loc. 28037 (C. A. S.), 6J 
miles north of Window bridge, SE4SW} Sec. 10, T. 21 N., R. 6 
W., M. D., western Glenn County, California. F. M. Anderson 
ami H. O. Jenkins, colls. Knoxville series, upper Jurassic. 
Height (incomplete) 45 mm. 



3 Hypotype: a described or figured specimen, used in publica- 
tion in extending or correcting the knowledge of a previously 
defined species (Frizzell, D. L. 33). 



EOCENE, OLIGOCENE, AND MIOCENE FOSSILS 

Explanation of Figure 62 (1-33) 



Fig. 62-1. Brachysphingus gabbi Stewart. Hypotype, No. 5700 
(Calif. Acad. Sci. Paleo. Type Coll.). Apertural view. From 
Loc. 27174 (C. A. S.), a quarter of a mile east and 200 feet north 
of SW. corner of Sec. 8, T. 1 N., R. 1 E., M. D., Contra Costa 
County, California. J. A. Taff and C. M. Cross, colls. Martinez 
formation, lower Eocene. Height 28.3 mm. 

Fig. 62-2. Brachysphingus gabbi Stewart. Another view of 
the specimen shown in figure 61-1. 

Fig. 62-3. Cardium (Schedocardia) brewerii Gabb. Hypo- 
type No. 5701 (Calif. Acad. Sci. Paleo. Type Coll.). Left valve. 



From Loc. 244 (C. A. S.), on east branch of Live Oak Creek 
about three-quarters of a mile from its mouth or from the edge 
of San Joaquin Valley. This locality is about 3 miles due east 
of the mouth of Grapevine Canyon, Kern County, California. 
Bruce G. Martin, coll. Tejon formation, upper Eocene. Altitude 
25.3 mm ; length 26.2 mm. 

Fig. 62-4. Spiroglyphus tejonensis Arnold. Hypotype, No. 
5941 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 31222 
(C. A. S.), 600 feet north and 4,400 feet east of southwest corner 
of Sec. 27, T. 23 S., R. 17 E., M. D., south of Big Tar Canyon, 



Characteristic Fossil s — II anna and Hertlei 



n 



169 




Fig. 61 (1 to 22). Cretaceous and Upper Jurassic fossils of California. 






170 



Paleontology and .Stratigraphy 



[Chap. VI 



Kings County, California. Type locality of the species. Earl 
Dillon, coll. "Avenal Sand," upper Eocene. Cross-section of a 
typical specimen, diameter 10 mm. 

A large number of specimens of this species from the type 
locality have been sectioned and they show very great variation 
in details. However, all of them show that the so-called spiral 
threads, grooves, or ridges are really sharp spiral plaits, usually 
three or four to the body whorl. These are very obscure and may 
be misleading on many weathered individuals. The apex or cen- 
ter of the whorls is ordinarily concealed in weathered specimens 
but the sections show uniformly, a mass of irregular twisting of 
the tubule. 

Fig. 62-5. Spiroglyphus tinajasensis Hanna and Hertlein. n. 
sp. Paratype,' No. 5975 (Calif. Acad. Sci. I'aleo. Type Coll.). 
From Loc. 31218 (C. A. S.), Sec. 20, T. 25 S., R. 18 E., M. D., 
Devils Den, Kern County, California. Cross-section, diameter 
9 mm. 

Fig. 62-6. Turritella andersoni Diekerson. Hypotype, No. 

5621 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 316 
(C. A. S.), Sec. 15, T. 18 S., R. 14 E., M. D„ Lillis ranch on 
Salt Creek, Fresno County, California. F. M. Anderson, coll. 
Domengine, upper Eocene. Altitude 32.8 mm. 

Fig. 62-7. Turritella andrrsoni Diekerson. Hypotype, No. 

5622 (Calif. Acad. Sci. Paleo. Type Coll.). From the same local- 
ity as the specimen shown in figure 62-6. Domengine, upper 
Eocene. Altitude 36 mm. 

Fig. 62-8. Nuculnna temblorensis Anderson and Martin. 
Hypotype, No. 5704 (Calif. Acad. Sci. Paleo. Type Coll.). Right 
valve. From Loc. 26064 (C. A. S.), Clyde De Lano well No. 1, 
Sec. 34, T. 28 S., R. 28 E., M. D., Kern County, California, depth, 
833-835 feet. Temblor, middle Miocene. Length 20.6 mm ; 
height 9.9 mm. 

Fig. 62-9. Nuculana washingtonensis Weaver. Syntype, 5 No. 
450b (Calif. Acad. Sci. Paleo Type Coll.). Left valve. From 
Loc. 256 (Univ. Washington Paleo. Coll.), in railway cuts on the 
O.-W. R. R. & N. Co., a quarter of a mile west and north of Lin- 
coln Creek Station in Sec. 27, T. 15 N., R. 3 W., W., Lewis 
County, Washington. In this region the bluffs extend above and 
below the railway track and for a distance along the track of 
about a mile. Lower Oligocene. 

This species has been reported to occur in beds referred to 
the Oligocene in California. 

Fig. 62-10. Gnleodea sutterensis Diekerson. Hypotype, No. 
5711 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 248 
(C. A. S.), 2 miles north and 80 degrees west of South Butte in 
the Marysville Buttes quadrangle, in a small gulch locally known 
as Fig Tree Gulch, an eighth of a mile east of the road, Sutter 
County, California. R. E. Diekerson, coll. Middle Eocene. Alti- 
tude 30 mm. 

Fig. 62-11. Pseudoperissolax blakei Gabb. Hypotype, No. 
5934 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 711 
(C. A. S.), on the east side of Grapevine Creek near the point 
where the stream flows out upon the valley floor ; the fossils were 
collected near the center of Sec. 20, T. 10 N., R. 20 W., S. B., 
Kern County, California. G. D. Hanna and M. A. Hanna, colls. 
Tejon, upper Eocene. Altitude (incomplete) 29.5 mm. 

Fig. 62-12. Spiroglyphus tinajasensis Hanna and Hertlein, 
n. sp. Holotype, No. 5974 (Calif. Acad. Sci. Paleo. Type Coll.). 
(Paratypes, ' Nos. 5933, A-F, and 5975). From Loc. 31218 
(C. A. S.), Sec. 20, T. 25 S., R. 18 E., M. D., Devils Den, Kern 
County, California. Upper Eocene. Greatest diameter 12.9 mm. 

Shell coiled, sharply keeled and with two shallow concentric 
grooves on the body whorl ; in cross-section body cavities round 
and symmetrical. 

This species is named for "Las Tinajas de Los Indios" (Tanks 
of the Indians) by which name the nearby locality was known. 

Species very similar to tejonensis and tinajasensit occur in the 
Eocene of the Gulf Coast region of Alabama, Texas, and Mexico. 
These have been discussed by Gardner (39, pp. 17-20, pi. 6), who 
placed them under the genus Tiihulostiuin. 

Fig. 62-13. Macrocallista pittsburgensis Dall. Plasto-hypo- 
type (from impression) No. 5667 (Calif. Acad. Sci. Paleo. Type 
Coll.). From Loc. 2267 (C. A. S.), diatomaceous shale with shell 
impressions from the 100-foot Leila zone 50 to 60 feet below the 
top, SEi Sec. 25, T. 16 S., R. 13 E., M. D„ in the first deep can- 
yon north of Arroyo Ciervo, south side, just below old Ciervo 
Mountain road, Fresno County, California. C. C. Church, coll. 
Kreyenhagen shale, Oligocene. Length 17.4 mm ; height 10.0 mm. 



Fig. 62-14. Macrocallista ronradiana Gabb. Hypotype, No. 
5623 (Calif. Acad. Sci. Paleo. Type Coll.). From the same loca- 
tion as the specimen shown in figure 62-3. Tejon, upper Eocene. 
Length 28 mm ; height 19.3 mm. 

Fig. 62-15. Turrilella latcsoni Diekerson. Hypotype, No. 
591(1 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 549 
(C. A. S.), west of Aliso Canyon (west), south side of Santa 
Susnna Mountains, near point where east boundary of Simi land 
grant crosses hogback ridge south of 3,384-foot hill not far above 
base of the "Tejon," Los Angeles County, California. W. S. W. 
Kew and C. Wagner, colls. Las Llajas formation, lower upper 
Eocene. Height 46.5 mm. 

Fig. 62-16. Turritella andersoni Diekerson. Hypotype, No. 
7737 (Calif. Acad. Sci. Paleo. Type Coll.). From the same local- 
ity as the specimens shown in figures 62-6 and 62-7. Domengine, 
upper Eocene. Altitude of slab 132 mm. 

This view shows a slab of Domengine sandstone filled with 
specimens of Turritella andersoni. These characteristic Turritella 
beds appear for several miles along the west side of the San Joa- 
quin Valley in Fresno County. 

Fig. 62-17. Eoeernina hnnnihali Diekerson. Hypotype, No. 
5962 (Calif. Acad. Sci. Paleo. Type Coll.). Apertur'al view, 
aperture incomplete. From Loc. 393 (C. A. S.), near southeast 
corner. NEJ Sec. 26 (near east line), T. 3 N., R. 17 W., S.B., 
in west bank of Aliso Canyon of Devil Creek, due west of Andrew 
Janglin's ranch in Sec. 25, Santa Susana quadrangle, Los Angeles 
County, California. R. G. Stoner and R. E. Diekerson, colls. 
Las Llajas formation, lower upper Eocene. Altitude 41.4 mm; 
width 38.6 mm. 

A very similar species has been described from the Eocene of 
Chiapas, Mexico (Cernina (Eoeernina) chiapasensis Gardner and 
Bowles ; 34, p. 243, figures 2 and 3 on p. 246. From "about 12 
miles east-south-east of Sayula, Chiapas, Mexico. Eocene.") 

Fig. 62-18. Turritella sargeanti Anderson and Hanna. Hypo- 
type, No. 5903 (Calif. Acad. Sci. Paleo. Type Coll.). From the 
same locality as the specimens shown in figures 62-3 and 62-14. 
Tejon, upper Eocene. Altitude 69.8 mm ; diameter of penultimate 
whorl 17 mm. 

Fig. 62-19. Turritella variata Conrad. Hypotype (Univ. 
Calif.). Plasto-hvpotvpe, No. 5665 (Calif. Acad. Sci. Paleo. Tvpe 
Coll.). From Loc. "A889" (Univ. Calif.) [from A887 (Univ. 
Calif.), Lompoc quadrangle, U. S. G. S. Topo. map, Santa Ynez 
Mountains, Santa Barbara County, California. Coarse-grained 
sandstone beds, outcropping in Nojoqui Creek an eighth of a mile 
east of coast highway bridge, 1.2 miles north of Gaviota Pass. 
W. L. Effinger, coll. (Loc. 4)]. Gaviota formation, upper Eocene. 
Altitude 56 mm ; diameter of body whorl 22.6 mm. 

Fig. 62-20. Spiroglyphus tejonensis Arnold. Hypotype, No. 
5940 (Calif. Acad. Sci. Paleo. Type Coll.). From the same local- 
ity as the specimen shown in figure 62-4. "Avenal Sand", upper 
Eocene. Greatest length approximately 13 mm. 

Fig. 62-21. Luria andersoni Waring. Hvpotvpe, No. 5712 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 364 (C. A. S.), 
Aliso Creek, Sec. 25, T. 3 N., R. 17 W., S. B., in canyon below 
Andrew Janglin's ranch house near Chatsworth, Los Angeles 
County, California. R. G. Stoner, coll. Las Llajas formation, 
lower upper Eocene. Altitude 24.6 mm. 

Fig. 62-22. Whitneya fieus Gabb. Hypotype, No. 5713 
(Calif. Acad. Sci. Paleo. Type Coll.). From the same locality as 
the specimens shown in figures 62-3, 62-14, and 62-18. Type 
Tejon, upper Eocene. Altitude 22 mm. 

Fig. 62-23. Retipirula crassitesta Gabb. Hypotype, No. 5915 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 396 (C. A. S.), 
lg miles S. 45° W., from B.M. 961, strike N. 50° W., dip 40° N., 
Santa Susana Mountains, Los Angeles County, California. R. E. 
Diekerson, coll. Martinez, lower Eocene. Altitude 18.8 mm. 

Fig. 62-24. Retipirula crassitesta Gabb. Hypotype, No. 
5915A (Calif. Acad. Sci. Paleo. Type Coll.). From the same 
locality as the specimen shown in figure 62-23. Martinez, lower 
Eocene. Altitude 21 mm. 

FIG. 62-25. Turritella merriami Diekerson. Hypotype, No. 
5709 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 29138 






* Faratype : a specimen, other than the holotype, upon which 
an original specific description is based (Frizzell, D. L. 33). 

Syntype : any specimen of the author's original material 
when no hoiotype was designated ; or any of a series of specimens 
described as "cotypes" of equal rank (Frizzell, D. L. 33). 



(' II A R A C T ERISTIC Fossil. 



\ S A AND II i: R T L E I N 



171 







Fig. 62 (1 to 33). Eocene, Oligocene, and Miocene fossils of California. 



172 



Paleontology and Stratigraphy 



[Chap. VI 



(C. A. S.), Buttes well No. 4'at a depth of about 2,800 feet, about 
3 miles west and 1J miles north of Sutter City, Sutter County, 
California. E. R. Leach, coll. Middle-Eocene. Altitude 38.8 mm. 

Fig. 62-26. Siphonalia sutterensis Dickerson. Hypotype, No. 
5710 (Calif. Acad. Sci. Paleo. Type Coll.). From the same local- 
ity as the specimen shown in figure 62-10. Middle Eocene. Alti- 
tude 15.4 mm. 

Fig. 62-27. Venericardia ionensis Waring. Hypotvpe, right 
valve, No. 7738 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 
1930 (C. A. S.), Sec. 17, T. 23 S., R. 17 E., M. D., half a mile 
south of Big Tar Canyon, Eocene sandstone reef, Kings County, 
California. O. P. Jenkins, coll. Upper Eocene. Altitude (beak 
to base) 103 mm; length 101.5 mm. 

Fig. 62-28. Pecten (Propeamusium) interradiatus Gabb. 
Hypotype, left valve, No. 5733 (Calif. Acad. Sci. Paleo. Type 
Coll.). From Loc. 899 (C. A. S.), from type locality of Kreyen- 
hagen shale on Canoas Creek, Kreyenhagen ranch, Kings County, 
California. G. D. Hanna, coll. Upper Eocene. Altitude 11.8 mm. 

Fig. 62-29. Volutocristata lajollaensis M. A. Hanna. Hypo- 
type No. 5714 (Calif. Acad. Sci. Paleo. Type Coll.), from the same 
locality as the specimen shown in figure 62-21. Las Llajas forma- 
tion, lower upper Eocene. Altitude 44 mm ; greatest diameter 
29.2 mm. 

Regarding the genus Volutocristata and related genera, see 
Gardner and Bowles (34, pp. 245-248). 

Fig. 62-30. Tejonia lajollaensis Stewart. Hypotype, No. 5666 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 393 (C. A. S.), 
near the southeast corner of NEJ Sec. 26 (near east line), T. 3 
N., R. 17 W., S. B., in west bank of Aliso Canyon of Devil Creek 
due west of Andrew Janglin's ranch in Sec. 25, Santa Susana 
quadrangle, Los Angeles County, California. R. G. Stoner and 

MIOCENE 



R. E. Dickerson, colls. Las Llajas formation, lower upper Eocene. 
Altitude (incomplete) 57.2 mm; greatest diameter 44.6 mm. 

This and allied species have been placed by writers in various 
genera, none of which seem entirely satisfactory for this well- 
known group. (See Woodring, 31a, p. 385.) We therefore pro- 
pose the genus Tejonia with the type Natica alveata Conrad 
(Blake, W. P. 55a, p. 10, Ap. to Rep. of W. P. Blake. "Locality. 

Canada de las Uvas." See Anderson and Hanna 25, p. 

119, pi. 6, fig. 2 ; pi. 7, fig. 1 ; pi. 15, fig. 17. Type locality). Due 
to a prior use of the name Natica alveata by Troschel in 1852, 
Conrad's species was renamed 4ino«rf//ina moragai by Stewart 
(26, p. 334, pi. 28, fig. 3. Tejon, Eocene). Cox (31, p. 38) has 
given a brief review of the Ampullospiridae. 

A species very similar to Tejonia lajollaensis has been 
described from the Eocene of Chiapas, Mexico (See Amaurellina 
cortezi Gardner and Bowles (34, p. 244, figs. 7 and 9 on p. 246. 
"About 12 miles east-north-east of Sayula, Chiapas, Mexico. 
Eocene."). 

Fig. 62-31. Venericardia hornii Gabb var. Hypotype, No. 
5982 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 12122 
H. H. (C. A. S.), Rose Canyon, San Diego, California. Henry 
Hemphill, coll. Rose Canyon formation, lower upper Eocene. 
Altitude 103.2 mm ; length 108 mm. 

View showing hinge of right valve. 

Fig. 62-32. Venericardia hornii Gabb var. View of exte- 
rior of right valve of the specimen shown in figure 62-31. 

Fig. 62-33. Turritella pachecoensis Stanton. Hypotype, No. 
5670 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 28645 
(C. A. S.), in gully 5,300 feet south along coast and 9,200 feet east 
of Kinton Point, Santa Cruz Island, Santa Barbara County, 
California. C. St. John Bremner, coll. Martinez, lower Eocene. 
Altitude (incomplete) 75.8 mm. 

FOSSILS 



Explanation of Figure 63 (1-24) 



FlO. 63-1. Pecten andersoni Arnold. Hypotype, right valve. 
No. 5739 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 202.', 
(C. A. S.), zone B along Kern River, Kern County, California. 
F. M. Anderson, coll. Temblor, middle Miocene. Length 44 mm ; 
height 40.5 mm. 

FIG. 63-2. Pecten andersoni Arnold. Hypotype, left valve, 
No. 5739A (Calif. Acad. Sci. Paleo. Type Coll.). From the same 
locality as the specimen shown in figure 63-1. Temblor, middle 
Miocene. Length 42.4 mm ; height 40.8 mm. 

Fig. 63-3. Astrodapsis whitneyi R£niond. Hypotype, No. 
5923 (Calif. Acad. Sci. Paleo. Type Coll.), from Loc. 137 
(C. A. S.) 1 to 1J miles north of the road along Quailwater 
Creek, San Luis Obispo County, California. Santa Margarita 
formation, upper Miocene. Greatest diameter 56.9 mm ; lesser 
diameter 54 mm. 

The genus Astrodapsis occurs commonly in the upper Miocene 
and lower Pliocene of California. 

Fig. 63-4. Turritella temhloris Wiedey. Para type, No. 2984 
(C. A. S.). From Loc. 567 (C. A. S.), from Dry Canyon, Topanga 
Canyon Road, about 3 miles south of Calabasas, Los Angeles 
County, California. J. O. Nomland, coll. Topanga formation, 
middle Miocene. Height 51.2 mm ; diameter of body whorl 28 mm. 

Fig. 63-5. Cancellaria posunculensis Anderson and Martin. 
Hypotype, No. 5725 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Loc. 65 (C. A. S.), hills just north of Kern River and northeast 
of Barker's ranch house, Kern County, California. Bruce G. 
Martin, coll. Temblor, middle Miocene. Height 24.3 mm ; diam- 
eter 10.8 mm. 

Fig. 63-6. Turritella ocoyana Conrad. Hvpotvpe, No. 5963 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 66 (C. A. S.), 
near the top of a prominent hill on the west side of Cottonwood 
Cieek and about a mile southeast of the Rio Bravo ranch house 
about 12 miles east of Bakersfield, Kern County, California. 
F. M. Anderson, coll. Temblor formation, middle Miocene. 
Height 54.2 mm ; diameter of body whorl 16.6 mm. 

Fig. 63-7. Pecten (Lyropecten) estrellanus Conrad. Hypo- 
type, right valve, No. 5900 (Calif. Acad. Sci. Paleo. Type Coll.). 
From Loc. 28473 (C. A. S.), west central part of SWJ SEi 
Sec. 16, T. 23 S., R. 13 E., M. D., Monterey County, California. 
N. L. Taliaferro, coll. Santa Margarita formation, upper Mio- 
cene. Length 92.8 mm ; height 84.6 mm. 



Fig. 63-8. Pecten (Lyropecten) crassicardo Conrad. Hypo- 
type, right valve, No. 5979 (Calif. Acad. Sci. Paleo. Type Coll.). 
From Loc. 2036 (C. A. S.), Sec. 29, T. 18 S., R. 14 E., M. D., 
Fresno County, California. F. M. Anderson, coll. Santa Mar- 
garita formation, upper Miocene. Length 113 mm ; height 103 mm. 

Fig. 63-9. Astrodapsis tumidus R^mond. Hvpotvpe, No. 
5706 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 2379 
((' A. S.), "Shell Ridge" about 100 yards northeast of quarry 
1J miles east (S. 76° E.) of Walnut Creek, Contra Costa County, 
California. J. L. Nicholson, coll. Astrodapsis tumidus zone, 
Neroly formation of the upper San Pablo, upper Miocene. Great- 
est diameter 31 mm. 

Fig. 63-10. Conus owenianus Arnold. Hypotype, No. 5708 
(Calif. Acad. Sci. Paleo. Type Coll.). From the same locality 
as the specimen shown in figure 63-5. Temblor, middle Miocene. 
Height 26 mm ; greatest diameter 25.9 mm. 

Fig. 63-11. Echinarachnius fairbanksi Arnold. Hypotvpe, 
No. 5738 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 251 
(C. A. S.), in Sespe Canyon, between Sespe and Piedra Blanca 
Creeks, about 18 miles north of Nordhoff (Ojai), Ventura County, 
California. B. W. Evermann, coll. Vaqueros, lower Miocene. 
Greatest diameter 51.5 mm. 

Fig. 63-12. Trochita filosa Gabb. Hypotype, No. 5731 
(Calif. Acad. Sci. Paleo. Type Coll.). From the same locality 
as the specimen shown in figure 63-5. Temblor, middle Miocene. 
Greatest diameter (incomplete) 16.8 mm; height approximately 
10.4 mm. 

Fig. 63-13. Lucina richthofeni Gabb. Hypotype, No. 5737 
(Calif. Acad. Sci. Paleo. Type Coll.). From the same locality 
as the specimen shown in figure 63-5. Temblor, middle Miocene. 
Length 15 mm ; height 15 mm. 

Fig. 63-14. Ostrea titan Conrad. Hypotype, left valve, No. 
5961 (Calif. Acad. Sci. Paleo. Tvpe Coll.). From Loc. 1282 
(C. A. S.), Sec. 20, T. 18 N., R. 15 E., M. D., 2 miles north of 
Domengine ranch house, Fresno County, California. G. D. Hanna, 
coll. Santa Margarita formation, upper Miocene. Height (beak 
to base) approximately 150 mm. 

Fig. 63-15. Ocenebra topangensis Arnold. Hypotype, No. 
5719 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 567 
(C. A. S.), Dry Canyon-Topanga Canyon road, about 3 miles 
south of Calabasas, Los Angeles County, California. J. O. Nom- 



Characteristic Fossil s— H anna and Hertlein 



173 




Fio. 63 (1 to 24). Miocene fossils of California 



174 



Paleontology and Stratigraphy 



[Chap. VI 



land, coll. Topanga formation, middle Miocene. Altitude 42.5 
mm ; diameter 26 mm. 

Fig. 63-16. Ostrea eldridgei Arnold. Hypotype, left vulve, 
No. 5964 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 2740!) 
(C. A. S.), 3,100 feet east and 1,600 feet north of the southwest 
corner of Sec. 31, T. 4 N., R. 18 W., S. B., Ventura County, Cali- 
fornia. C. E. Leach, coll. Vaqueros, lower Miocene. Height 
(heak to base) 128.5 mm; width 88.4 mm; thickness (hoth valves) 
69.8 mm. 

Fig. 63-17. Trophon kernensis Anderson. Hypotype, No. 
5718 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 126 
(C. A. S.), from rock in bed of a small creek running southeast 
and emptying into Shell Creek near the center of Sec. 34, T. 28 S., 
R. 15 E., M. D., San Luis Obispo County, California. Bruce G. 
Martin, coll. Temblor, middle Miocene. Altitude 49.3 mm ; 
diameter 32.5 mm. 

FlG. 63-18. Miltha saticfaecrucis Arnold. Hypotype, left 
valve, No. 5740 (Calif. Acad. Sci. Paleo. Type Coll.). From the 
same locality as the specimen shown in 
lower Miocene. Height 42.5 mm. 

FlO. 63-19. Bruclarkia barkeriana 
5741 (Calif. Acad. Sci. Paleo. Type 
(C. A. S.), hills just north of Kern 
Barker's ranch house, Kern County, California. Bruce G. Martin, 
coll. Temblor, middle Miocene. Height 54.3 mm ; diameter 
30.5 mm. 

Fig. 63-20. Echinarachnius merriami Anderson. Hvpotype, 
No. 5707 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 478 



figure 63-16. Vaqueros, 

Cooper. Hypotype No. 
Coll.). From Loc. 65, 
River and northeast of 



(C. A. S.), Temblor beds north of Cantua Creek, Fresno County, 
California. Temblor, middle Miocene. Greatest diameter 12 mm. 
Abactinal view. 

Fig. 63-21. Trophosycon kernianum Cooper. Hypotype, No. 
5717 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 64 (C. 
A. S.), in the bed of a small gulch about \\ miles northeast of 
Barker's ranch house on Kern River, Kern County, California. 
Bruce G. Martin, coll. Temblor, middle Miocene. Height 48.5 
mm ; diameter 37.8 mm. 

Fig. 63-22. Turritella ocoyana bosei Hertlein and E. K. 
Jordan. Hypotype, No. 5702 (Calif. Acad. Sci. Paleo. Type 
Coll.). From Loe. 146 (C. A. S.), 3 miles south of bridge on 
San Juan River, in southwest corner of SEJ Sec. 34, T. 29 S., 
R. 17 E., M. D., San Luis Obispo County, California. Temblor, 
middle Miocene. Altitude 43.4 mm. 

Fig. 63-23. Turritella ocoyana bosei Hertlein and E. K. 
Jordan. Hypotype, No. 5669 (Calif. Acad. Sci. Paleo. Type 
Coll.). From Loc. 1929 (C. A. S.), Miocene sandstone on Garzas 
Creek, Sec. 10, T. 23 S., R. 16 E., M. D., Kings County, Cali- 
fornia. Temblor, middle Miocene. O. P. Jenkins, coll. Altitude 
55 mm. 

Fig. 63-24. Turritella inezana Conrad. Hvpotvpe, No. 5543 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1153 (C. A. S.), 
San Augustine Canyon, in bed of creek about } to 1 mile from 
mouth of canyon. Santa Rosa Island, Santa Barbara County, 
California. L. G. Hertlein and E. Rixford, colls. Vaqueros, 
lower Miocene. Altitude (incomplete) 109 mm. 



MIOCENE, PLIOCENE, AND PLEISTOCENE FOSSILS 

Explanation of Figure 64 (1-20) 






Flo. 64-1. Cardium (Mexieardia) procerum Sowerby. Hypo- 
type, right valve, No. 5948 (Calif. Acad. Sci. Paleo. Type Coll.). 
From Loc. 110 (C. A. S.), at the foot of 26th Street, San Diego, 
California. Upper Pleistocene. Length 77.5 mm ; height 82 mm. 

Fig. 64-2. Turritella jetcettii Carpenter. Hypotype No. 5668 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 93 (C. A. S.), 
from loose sand immediately underlying the upper San Pedro 
series, Deadman Island, San Pedro, Los Angeles County, Califor- 
nia. Lower San Pedro formation, lower Pleistocene. Height 64 
mm ; diameter of body whorl 18.2 mm. 

FlG. 64-3. Crepidula princeps Conrad. Hypotype, No. 5937 
(Calif. Acad. Sci. Paleo. Type Coll.). (Original Calif. State Min. 
Bur. No. 14639). Collected from Rincon Asphalt Mine, Santa 
Barbara County, California, November 12, 1895. Upper Pliocene. 
Length 100.5 mm ; width 65.5 mm ; thickness 49 mm. 

Fig. 64-4. Ostrea vespertina Conrad. Hypotype, left valve, 
No. 5912 (Calif. Acad. Sci. Paleo. Type Coll.). From Loe. 725 
(C. A. S.), from coarse conglomerate 1 mile north of Camulos, 
Ventura County, California. W. L. Watts, coll. (No. 4, Calif. 
State Min. Bur. Coll.). Upper Pliocene. Height (beak to base) 
91 mm ; width 79 mm. 

Fig. 64-5. Dendraster venturaensis Kew. Hypotype, No. 
5938 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 28461 
(C. A. S.), 2} miles N. 2° W. from B. M. 313 above the Crepi- 
dula and Chrysodomus zone in Las Posas Valley, Santa Paula 
quadrangle, Ventura County, California. C. M. Carson and M. 
McDivitt, colls. Upper Pliocene. Greatest diameter 95.9 mm ; 
lesser diameter 89 mm ; thickness 17.5 mm. 

Fig. 64-6. Dendraster venturaensis Carson. View of profile of 
the specimen shown in figure 64-5. 

Fig. 64-7. Olivella biplieata Sowerby. Hypotype, No. 5732 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 546 (C. A. S.), 
from Wilson's Ranch, near Russian River about li to 2 miles 
south of the intersection of the road running west from Windsor 
with the north-south road, Sonoma County, California. R. E. 
Dickerson, coll. Merced, lower upper Pliocene. Height 18.5 mm ; 
diameter 9.5 mm. 

Fig. 64-8. Forreria belcheri Hinds. Hypotype, No. 5723 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 2364 (C. A. S.), 
North Dome of Kettleman Hills, Kings County, California. Peeten 
coalingaensis zone, middle Pliocene. Altitude 44.6 mm ; diameter 
31.5 mm. 

Fig. 64-9. Acila castrensis Hinds. Hypotype, right valve, 
No. 5727 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 710 



(C. A. S.), oil sand in Elsmere Canyon, first large creek to left 
above Standard Oil pumping plant, about 1J miles from plant. 
Strata 75 feet thick, dip 15° SW. Overlain by 2,000-3,000 feet 
of conglomerate. Los Angeles County, California. G. D. Hanna, 
coll. Middle Pliocene. Height (beak to base) approximately 

12.5 mm. 

Fig. 64-10. Lucina (Lvcinisea) nuttalli Conrad. Hypotype, 
right valve, No. 5735 (Calif. Acad. Sci. Paleo. Type Coll.). 
From the same locality as the specimen shown in figure 64-2. 
Lower Pleistocene. Length 27.2 mm ; height 25 mm. 

Fig. 64-11. Peeten (Deleetopecten) pedroanus Trask. Hypo- 
type. right valve No. 5734 (Calif. Acad. Sci. Paleo. Type Coll.). 
From Loc. 1894 (C. A. S.), from diatomaceous shale, 220 yards 
east of the breakwater at San Pedro, Los Angeles County, Cali- 
fornia. L. G. Hertlein, coll. Upper Miocene. Length 15.4 mm ; 
height 14.5 mm. 

This specimen is from sediments occurring in the area origi- 
nally indicated as the type locality of this species. 

Fig. 64-12. Cantharus fortis Carpenter. Hypotype, No. 5742 
(Calif. Acad. Sci. Paleo. Type Coll.). (Original No. 14637, Calif. 
State Min. Bur.) From the same locality as the specimen shown 
in figure 64-3. Upper Pliocene. Height 58.8 mm ; diameter 
35 mm. 

Fig. 64-13. Gonidea coalingensis Arnold. Hypotype, left 
valve, No. 5947 (Calif. Acad. Sci. Paleo. Type Coll.)'. From Loc. 
2371 (C. A. S.), east flank of North Dome, Kettleman Hills, Kings 
County, California. F. M. Anderson, coll. Basal Tulare, upper 
Pliocene. Length 74 mm; height 36 mm; thickness (two valves) 
17.4 mm. 

Fig. 64-14. Molopophorus anglonana Anderson. Hypotype, 
No. 5724 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 65 
(C. A. S.), in the hills just north of Kern River and northeast- 
east of Barker's ranch house, Kern County, California. Temblor, 
middle Miocene. Bruce G. Martin, coll. Height 33 mm ; diameter 
20 mm. 

Fig. 64-15. Bittium asperum Gabb. Hypotype, No. 5729 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 82 (C. A. S.), 
sea cliff near bath house immediately southwest of the Porter 
Hotel, Santa Barbara, California. Pleistocene. Altitude 13 mm. 

Fig. 64-16. Lucina (Lucinoma) acutilineata Conrad. Hypo- 
type, right valve, No. 5730 (Calif. Acad. Sci. Paleo. Type Coll.). 
From Loc. 27276 (C. A. S.), Temblor Reef in west center of Sec. 
21, T. 19 S., R. 15 E., M. D. t south of Oil City, Fresno County, 
California. Temblor, middle Miocene. Length 28.5 mm ; height 

26.6 mm. 



Characteristic Fossils — II anna and Hertlein 



175 




Fig. 64 ( 1 to 20). Miocene, Pliocene, and Pleistocene fossils of Californl 



176 



P ALEO N TOLO G Y A ND STRATIGRAPHY 



[Chap. VI 



Flo. 64-17. Turritella cooperi Carpenter. Hypotype, No. 
5703 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 28484 
(C. A. S.), south flank of South Mountain in road out in west 
bank of unnamed canyon 2} miles N. 21° W. from B. M. 313, 
Santa Paula quadrangle, U. S. Geol. Survey, Topo. sheet, Ven- 
tura County, California. C. M. Carson, coll. Upper Pliocene. 
Height 35.5 mm ; diameter of body whorl 11 mm. 

PlO. 64-18. Rapana vaguerosensis imperialis Hertlein and 
E. K. Jordan. Hypotype, No. 2841 (C. A. S.) (Original No. 
12322 Calif. State Min. Bur.). From Santa Rosa Island, Santa 
Barbara County, California. Vaqueros, lower Miocene. Height 
102.2 mm ; diameter 84 mm. 

Fig. 64-19. Cardita calif ornica Dall. Hypotype, right valve. 
No. 5736 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 77 



(C. A. S.), in railroad cut 1 mile north of Schumann Station, 
about 6 or 7 miles south of Guadalupe, Santa Barbara County, 
California. Middle Pliocene. Altitude 21.9 mm. View of exte- 
rior. 

FlG. 64-20. Pecten (Vertipecten) hoicersi Arnold. Hypotype, 
right valve. Xo. 7739 (Calif. Acad. Sci. Paleo. Type Coll.). From 
SWi Sec. 30. T. 26 S., R. 17 E., M. D., Temblor Range, Kern 
County, California. 250-500 feet above basal Miocene. E. J. 
Roche, coll. Vaqueros, lower Miocene. Length 170 mm ; height 
185 mm. 

On the left valve of this species every second or third rib is 
raised above the intervening ones. The species occurs in the 
upper Vaqueros and lower Temblor. 



PLIOCENE FOSSILS 

Explanation of Figure 65 (1-18) 



FlO. 65-1. Pecten (Patinopecten) lohri Hertlein. Hypotype, 
right valve, No. 7734 (Calif. Acad. Sci. Paleo. Type Coll.). From 
beds at railroad bridge across Waltham Creek, about 2 miles south- 
west of Coalinga, Fresno County, California (F. M. Anderson). 
Jacalitos formation, lower Pliocene. Height (beak to base) 123 
mm ; length 124 mm. 

This species was formerly known as Pecten oireni Arnold (not 
Ptcten oweni Sowerby). 

FlG. 66-2. Littorina mariana Arnold. Hypotype, No. 5722 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 26811 
(C. A. S.), south center of Sec. 17, T. 23 S., R. 19 E., M. P., 
Kettleman Hills, Kings County, California. Etchegoin, upper 
Pliocene. Height 13.3 mm; diameter 11.4 mm. 

Fig. 65-3. Pecten (Patinopecten) kealeyi Arnold. Hypotype, 
right valve, No. 5920 (Calif. Acad. Sci. Paleo. Type toll.). 
From Loc. 105 (C. A. S.), Pacific Beach, San Diego, Califor- 
nia. San Diego formation, middle Pliocene. Height 72 mm ; 
length 78 mm. 

Fig. 65-4. Scalez petrolia Hanna and Gaylord. Hypotype, 
No. 5901 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 885 
(C. A.^S.), at a depth of 3,208 feet in well No. 55 Pacific Oil Co., 
Sec. 27, T. 30 S., R. 24 E., M. D., Elk Hills, Kern County, Cali- 
fornia. J. H. Menke, coll. Etchegoin formation, upper Pliocene. 
Diameter of core 46 mm. 

Left of the central figure of Scalez petrolia the impression 
of a freshwater gastropod is visible. Scalez petrolia is believed 
to be the operculum of this or a similar gastropod. MacNeil (39, 
p. 357) has cited the genus from beds of Cretaceous age in 
Montana. 

FlG. 65-5. Clathrodrillia mercedensis Martin. Hypotype. No. 
5716 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 28617 
(C. A. S.), on southeast slope of hill about 2* miles south and a 
little west of the intersection of lines of Lat. 37° 25' N. and Long. 
122° 10' W., M. D., Palo Alto quadrangle. 1'. S. Geol. Surv. Topo. 
sheet. About 3§-3i miles south of the Stanford University quad- 
rangle, Santa Clara County, California. L. G. Hertlein and 
S. French, colls. Merced formation, lower upper Pliocene. 
Height 20.8 mm. 

This species occurs commonly in the Merced formation in the 
region about San Francisco Bay. 

Fig. 65-6. Mulinia densata Conrad. Hypotype, left valve. 
No. 5743 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 26820 
(C. A. S.), NW} Sec. 19, T. 23 S., R. 19 E., M. D., Kettleman 
Hills, Kings County, California. Mulinia zone. Etchegoin for- 
mation, upper Pliocene. Length 32.5 mm ; height 30 mm. View 
of interior. 

Fig. 65-7. Mulinia densata Conrad. Hypotype, right valve, 
No. 5743A (Calif. Acad. Sci. Paleo. Type Coll.). From the'same 
locality as the specimen shown in figure 65-6. Length 45.5 mm ; 
height 41 mm. 

Fig. 65-8. Nassarius californianus Conrad. Hypotype, No. 
5720 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1397 
(C. A. S.), Federal Exploration Company, well Kinsella No. 1, 
northeast corner of SEi Sec. 15, T. 22 S., R. 24 E., M. D., Tulare 
County, California. Depth 2,760 feet. Etchegoin formation, 
upper Pliocene. Height 12 mm ; diameter 7 mm. 



Fig. 65-9. Nassarius californianus Conrad. Hypotype, No. 
5721 (Calif. Acad. Sci. Paleo. Type Coll.). From the same local- 
ity as the specimen shown in figure 65-8. Etchegoin formation, 
upper Pliocene. Height 15 mm ; diameter 8 mm. 

FlG. 65-10. Pecten coalingacnsis Arnold. Hypotype, right 
valve, No. 5946 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Loc. 698 (C. A. S.), northwest corner of Sec. 35, T. 21 S., 
R. 17 E., M. D., North Dome, Kettleman Hills, Kings County, 
California. Pecten coalingaensis zone. Etchegoin formation, upper 
Pliocene. Length 58.2 mm ; height 55.9 mm ; thickness 21 mm. 

Flo. 65-11. Area trilineata Conrad. Hvpotvpe, right valve, f 
No. 5922A (Calif. Acad. Sci. Paleo. Type Coll.). From Loc 26805 
(C. A. S.), center SEi Sec. 30, T. 21 S., R. 17 E., M. D. Kettle- > 
man Hills, Fresno County, California. Area zone. Etchegoin i 
formation, upper Pliocene. Length 68.4 mm; height 55 mm. 

Fig. 65-12. Mya japonica Jay. Hypotype, right valve, No. i 
5925 (Calif. Acad. Sci. Paleo. Type Coll.). From 600 feet west 
and 600 feet south of northeast corner of Sec. 31, T. 21 S., R. | 
17 E., M. D., North Dome, Kettleman Hills, Fresno County, Cali- 1 
fornia. Mya zone. Etchegoin formation, upper Pliocene. Length j 
76 mm ; height 49 mm. 

Fig. 65-13. Mya japonica Jay. Hypotype, left valve, No. I 
5925A (Calif. Aead. Sci. Paleo. Type Coll.). From the same 
localitj as the specimen shown in figure 65-12. Mya zone. Etche- | 
goin formation, upper Pliocene. View of inside of left valve. 
Length 89.7 mm ; height 52.7 mm. 

Fig. 65-14. Pecten bellus Conrad. Hypotype, right valve, No. I 
5919 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 28559 
(C. A. S.), at base of Santa Barbara sands and marls on trail 
on northeast slope of Packard's Hill, Santa Barbara, California. 
T. W. Dibblee, Jr., coll. Upper Pliocene. Length 95 mm ; height 
81.6 mm. (Specimen slightly distorted.) 

FlG. 65-15. Amphissa versicolor Dall var. Hypotype, No. 
5728 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 568 (C. 
A. S.), from railroad cut J mile northeast of Schumann, Santa 
Barbara County, California. R. E. Dickerson, coll. Pliocene, 
probably upper. Height 10.6 mm ; diameter 4.8 mm. 

Fig. 65-16. Kelletia kettlemanensis Arnold. Hypotype, No. 
5902 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 27072 
(C. A. S.), center of Sec. 16, T. 22 S., R. 18 E., M. D., Kettleman 
Hills, Kings County, California. Upper Mulinia zone. Etchegoin 
formation, upper Pliocene. Height 85.2 mm ; diameter 63.3 mm. 

Fig. 65-17. Area trilineata Conrad. Hypotype, left valve, No. 
5922 (Calif. Acad. Sci. Paleo. Type Coll.). From the same local- 
ity as the specimen shown in figure 65-11. Area zone. Etchegoin 
formation, upper Pliocene. Exterior of left valve. Length 68 
mm ; height 55 mm. 

Fig. 65-18. Pecten etchegoini Anderson. Hypotype, left valve, 
No. 5945 (Calif. Acad. Sci. Paleo. Type Coll.). From Loe. 2032 
(C. A. S.), NEi Sec. 26, T. 22 S., R. 16 E., M. D., Fresno 
County, California. Etchegoin formation, middle Pliocene. 

The type specimen of Pecten wattsi Arnold was apparently 
lost in the San Francisco fire and earthquake in 1906 ; it came 
from approximately the same locality as our No. 5945 which is 
here designated lectotype of this species. Length 57 mm ; height 
62 mm. 



Characteristic Fossil s — II anna and Hertlein 



177 







Fig. 65 (11 to IS). Pliocene fossils at California. 



178 



Paleontology and Stratigraphy 



[Chap. VI 



DIATOMS (CRETACEOUS TO RECENT) 
Explanation of Figure 66 (1-21) 



Fig. 66-1. Hemiaulus claviger Schmidt. Hypotype, No. 3053 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 894 (C. A. S.), 
Phoenix Canyon, 7 miles north of Coalinga, Fresno County, Cali- 
fornia. Kreyenhagen shale. Oligocene or upper Eocene. Length 
0.10 mm; width 0.044 mm. (Hanna, G. D. 27, p. 113, pi. 18, 
fig. 8.) 

Fig. 66-2. Diploneis exempta Schmidt. Hypotype. No. 3354 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 (C. A. S.), 
4 miles east of Del Monte, Monterey County, California. Upper 
Monterey shale, upper Miocene. Length 0.1152 mm ; width 0.0372 
mm. 

Fig. 66-3. Diploneis ornata Schmidt. Hypotype, No. 3355 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 (C. A. S.), 
4 miles east of Del Monte, Monterey County, California. Upper 
Monterey shale, upper Miocene. Length 0.1440 mm ; width 0.0550 
mm. 

Fio. 66-4. Meretrosulus gracilis Hanna. Paratype, No. 2020 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 943 (C. A. S.), 
Moreno Gulch, Panoche Hills, Fresno County, California. Upper 
Moreno shale, Upper Cretaceous. Length 0.0500 mm. (Hanna, 
G. D. 27a, p. 24, pi. 3, fig. 10.) 

Fig. 66-5. Rhaphoneis rhombus Ehrenberg. Hypotype, No. 
3352 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 26482 
(C. A. S.), Sec. 11, T. 25 S., R. 19 E., M. D., South Dome, Ket- 
tleman Hills, Kern County, California ; about 100 feet below 
Mulinia zone. H. M. Horton, coll. Etchegoin, Pliocene. Length 
0.0554 mm ; width 0.0220 mm. 

Fig. 66-6. Rhaphoneis rhombus Ehrenberg. Hypotype, No. 
3352a (Calif. Acad. Sci. Paleo. Type Coll.). From same locality 
as figure 66-5. Length 0.0836 mm ; width 0.020 mm. 

Fig. 66-7. Oephyria giganlea Greville. Hypotype, No. 3356 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 (C. A. S.), 
4 miles east of Del Monte, Monterey County, California. Upper 
Monterey shale, upper Miocene. Length 0.1440 mm ; width 0.0290 
mm. 

Fig. 66-8. Triceratium montereyi Brightwell. Hypotype, No. 

3360 (Calif. Acad. Sci. Paleo. Type Coll.). From Loe. 866 (C. A. 
S.), 4 miles east of Del Monte, Monterey County, California. 
Upper Monterey shale, upper Miocene. Length of one side 0.140 
mm. 

Fig. 66-9. Cymatogonia amblyoeeras Ehrenberg. Hypotype, 
No. 3178 (Calif. Acad. Sci. Paleo. Type Coll.). From. Loc. 1068 
(C. A. S.), Sharktooth Hill, Kern County, California. Temblor, 
middle Miocene. Length of one side 0.090 mm. (Hanna, G. D. 
32, p. 186, pi. 10, fig. 5. Snyder, L. C. 32, p. 219, fig. 77-3.) 

Fig. 66-10. Auliscus californicus Grunow. Hypotype, No.. 
3353a (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1277 (C. 
A. S.), 3.7 miles north of Carmel River on road from Salinas-Mon- 
terey highway to Tassajara Springs, Monterey County, California, 
near granite contact. Monterey shale, upper Miocene. Diameter 
0.0782 mm. (Hanna, G. D. 30a, p. 7.) 

Fig. 66-11. Xanthiopyxis umbonutus Greville. Hvpotype, No. 

3361 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 860 (C. A. 



S.), 4 miles east of Del Monte, Monterey County. California. 
Upper Monterey shale, upper Miocene. Diameter 0.080 mm. 

Fig. 66-12. Lithodesmium cornigerum Brun. Hypotype, No. 
3136 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 1220 (C. 
A. S.), 4 miles west of Casmalia, Santa Barbara County, Cali- 
fornia. Pliocene. Distance between tips of two arms 0.0630 mm. 
(Hanna, G. D. 30b, pp. 189-191, pi. 14, fig. 10.) 

Fig. 66-13. Rutilaria epsilon Greville. Hypotype, No. 3095 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 (C. A. S.), 
4 miles east of Del Monte, Monterey County, California. Upper 
Monterey shale, upper Miocene. Length 0.1516 mm; width 0.0258 
mm. (Hanna, G. D. 28, pi. 8, fig. 3.) 

Fig. 66-14. Melosira clavigera Grunow. Hypotype, No. 3358 
(Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 (C. A. S.), 
4 miles east of Del Monte, Monterey County, California. Upper 
Monterev shale, upper Miocene. Diameter 0.0665 mm. (L. C. 
Snyder 32, p. 219, fig. 77-5.) 

Fig. 66-15. Cocconeis baldjikiana Grunow. Hypotype, No. 
3349 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 26482 
(C. A. S.), Sec. 11, T. 25 S., R. 19 E., M. D., South Dome Kettle- 
man Hills, Kern County, California ; about 100 feet below Mulinia 
zone. H. M. Horton, coll. Etchegoin, Pliocene. Length O.O720 
mm ; width 0.0380 mm. 

Fig. 66-16. Glyphodiseus stellatus Greville. Hypotype, No. 
3357 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 
(C. A. S.), 4 miles east of Del Monte, Monterey County, Califor- 
nia. Upper Monterey shale, upper Miocene. Diameter 0.0747 mm. 

Fig. 66-17. Frustulia leicisiana Greville. Hypotype, No. 
3351 (Calif. Acad. Sci. Paleo. Type ColL). From Loc. 26482 
(C. A. S.), Sec. 11, T. 25 S., R. 19 E., M. D., South Dome, Kettle- 
man Hills, Kern County, California; about 100 feet below Mulinia 
zone ; Etchegoin, Pliocene. H. M. Horton, coll. Length 0.2568 
mm; width 0.0436 mm. 

Fig. 66-18. Frustulia leicisiana Greville. Hypotype, No. 
3353 (Calif. Acad. Sci. Paleo. Type Coll.). A living specimen 
from Bolinas Bay, Marin County, California, to show character- 
istic markings. Length 0.1264 mm ; width 0.0286 mm. 

Fig. 66-19. Coscinodiscus asteromphalus Ehrenberg. Hypo- 
type, No. 3350 (Calif. Acad.- Sci. Paleo. Type Coll.). From Loc. 
26482 (C. A. S.), Sec. 11, T. 25 S., R. 19 E., M. D., South 
Dome Kettleman Hills, Kern County, California ; about 100 feet 
below Mulinia zone. Etchegoin, Pliocene. Diameter 0.2728 mm. 

Fig. 66-20. Stictodiscus californicus Greville. Hypotype, No. 
3359 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 866 
(C. A. S.), 4 miles east of Del Monte, Monterey County, Cali- 
fornia. Upper Monterey shale, upper Miocene. Diameter 0.0508 
mm. 

Fig. 66-21. Melosira granulata Ehrenberg. Hypotype, No. 
3362 (Calif. Acad. Sci. Paleo. Type Coll.). From Loc. 26863 
(C. A. S.), depth 349-375 feet in Prospect well No. 10, Sec. 14, T. 
12 S., R. 11 E., M. D., Laguna Seca district, Fresno County, 
California. Upper Pliocene. Length 0.1142 mm ; width 0.0170 
mm. 



FORAMINIFERA (CRETACEOUS TO PLIOCENE) 
Explanation. of Figure 67 (1-49) 



Fig. 67-1. Elphidium hannai Cusbman and Grant. Hypotype, 
No. 7740 (Calif. Acad. Sci. Paleo. Type Coll.). From Superior 
Oil Co., Hansen well No. 1, Sec. 26, T. 21 S., R. 17 E., M. D., 
Fresno County, California ; depth 1,345 feet. San Joaquin forma- 
tion, upper Pliocene. Width 0.65 mm; height 0.76 mm. Side 
view. 

Fig. 67-2. Elphidium hannai Cushman and Grant. Same 
specimen as figure 67-1. Apertural view. 

Fio. 67-3. Elphidium hughesi Cushman and Grant. Hypo- 
tvpe, No. 7741 (Calif. Acad. Sci. Paleo. Type Coll.). From Gen- 
eral Petroleum Corp., K. C. L. well No. 25-1, Sec. 25, T. 26 S., 
R. 25 E., M. D., MacFarland district, Kern County, California ; 
depth 2,624 feet. San Joaquin formation, upper Pliocene. Width 
0.26 mm ; height 0.30 mm. Side view. 

Fio. 67-4. Elphidium hughesi Cushman and Grant. Same 
specimen as figure 67-3. Apertural view. 



Fig. 67-5. Buliminella elegantissima d'Orbigny. Hypotype, 
No. 7742 (Calif. Acad. Sci. Paleo. Type Coll.). From King 
Tulare Syndicate Palmer well No. 1, Sec. 19, T. 21 S., R. 23 E., 
M. D., Tulare County, California ; depth 5,282 feet. San Joaquin 
formation, upper Pliocene. Width 0.12 mm ; height 0.32 mm. 
Side view. 

Fig. 67-6. Buliminella 
No. 7743 (Calif. Acad. Sci. 
and depth as figure 67-5. 
Side view. 

Fig. 67-7. Buliminella elegantissima d'Orbigny. 
men as figure 67-6. Apertural view. 

Fig. 67-8. Eponides exigua H. B. Brady. Hypotype, No. 
7744 (Calif. Acad. Sci. Paleo. Type Coll.). From King Tulare 
Syndicate, Palmer well No. 1, Sec. 19, T. 21 S., R. 23 E., M. D., 
Tulare County, California ; depth 5,282 feet. San Joaquin forma- 



elegantissima d'Orbigny. Hypotype, 

Paleo. Type Coll.). From same well 

Width 0.11 mm; height 0.25 mm. 



Same speci- 



Characteristic Fossil s — II anna and Hertlein 



179 




Fie 66 (1 to 21). Diatoms (Cretaceous to Recent) of California. (Microscopic fossil plants with siliceous tests). 



180 



Paleontology and Stratigraphy 



[Chap. VI 



tion, upper Pliocene. Width 0.25 mm ; height 0.-29 mm. Dorsal 
view. 

Fig. 67-9. Eponides exigua H. B. Brady. Same specimen 
as figure 67-8. Ventral view. 

Fig. 67-10. Eponides exigua H. B. Brady. Same specimen 
as figure 67-8. Apertural view. 

Fig. 67-11. Rotalia bcccarii tepida Cushman. Hypotype, No. 
7745 (Calif. Acad. Sci. Paleo. Type Coll.). From Graham and 
Young, McAdams well No. 1, Sec. 26, T. 29 S., R. 23 E., M. D., 
Kern County, California ; depth 5,812 feet. San Joaquin forma- 
tion, upper Pliocene. Width 0.22 mm ; height 0.24 mm. Dorsal 
view. 

Fig. 67-12. Rotalia beccarii tepida Cushman. Same speci- 
men as figure 67-11. Ventral view. 

Fig. 67-13. Rotalia beccarii tepida Cushman. Same speci- 
men as figure 67-11. Peripheral view. 

Fig. 67-14. Elphidium hannai Cushman and Grant. Hypo- 
type, No. 7746 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Superior Oil Co., Hansen well No. 1, Sec. 26, T. 21 S., R. 17 E., 
M. D., Fresno County, California ; depth 1,345 feet. San Joaquin 
formation, upper Pliocene. Width 0.60 mm ; height 0.70 mm. 
Side view. 

Fig. 67-15. Elphidium hannai Cushman and Grant. Same 
specimen as figure 67-14. Apertural view. 

Fig. 67-16. Bolivina brevior Cushman. Hypotype, No. 7747 
(Calif. Acad. Sci. Paleo. Type Coll.). From Associated Oil Co., 
Whepley well No. 1, Sec. 35, T. 21 S., R. 17 E., M. D., Kettleman 
Hills, Fresno County, California; depth 5,465-5,484 feet. Reef 
Ridge shale, upper Miocene. Width 0.15 mm ; height 0.31 mm. 
Side view. 

Fia. 67-17. Bolivina brevior Cushman. Same specimen as 
shown in figure 67-16. Apertural view. 

Fig. 67-18. Virgulina subplana Barbat and Johnson. Hypo- 
type, No. 7748 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Associated Oil Co., Whepley well No. 1, Sec. 35, T. 21 S„ R. 17 
E., M. D., Kettleman Hills, Fresno County, California ; depth 
5,465-5,484 feet. Reef Ridge shale, upper Miocene. Width 0.13 
mm ; height 0.36 mm. Side view. 

Fig. 67-19. Virgulina culiforniensis Cushman. Hypotype, No. 
7749 (Calif. Acad. Sci. Paleo. Type Coll.). From Associated Oil 
Co., Whepley well No. 1, Sec. 35, T. 21 S., R. 17 E., M. D., 
Kettleman Hills, Fresno County, California ; depth 5,465-5,484 
feet. Reef Ridge shale, upper Miocene. Width 0.18 mm ; height 
0.54 mm. Side view. 

Fig. 67-20. Bolivina obliqua Barbat and Johnson. Hypo- 
type, No. 7750 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Associated Oil Co., Watson well No. 1, Sec. 34, T. 22 S., R. 18 E , 
M. D., Kings County, California ; depth 5,745-5,750 feet. Reef 
Ridge shale, upper Miocene. Width 0.21 mm ; height 0.54 mm. 
Side view. 

Flo. 67-21. Bolivina obliqua Barbat and Johnson. Same 
specimen as figure 67-20. Apertural view. 

Fig. 67-22. Buliminella brevior Cushman. Hypotype, No. 

7751 (Calif. Acad. Sci. Paleo. Type Coll.). From Associated Oil 
Co., Whepley well No. 1, Sec. 35, T. 21 S., R. 17 E., M. D., 
Kettleman Hills, Fresno County, California ; depth 5,465-5,484 
feet. Reef Ridge shale, upper Miocene. Width 0.18 mm ; height 
0.30 mm. Ventral view. 

Fig. 67-23. Valvulineria miocenica Cushman. Hypotype, No. 

7752 (Calif. Acad. Sci. Paleo. Type Coll.). From Clyde De Lano 
well No. 1, Sec. 34, T. 28 S., R. 28 E., M. D., Kern County, Cali- 
fornia ; depth 750-770 feet. Temblor formation, middle Miocene. 
Width 0.62 mm ; height 0.76 mm. Ventral view. 

Fig. 67-24. Bolivina sp. Hypotype, No. 7753 (Calif. Acad. 
Sci. Paleo. Type Coll.). From Associated Oil Co., Whepley well 
No. 1, Sec. 35, T. 21 S., R. 17 E., M. D. Kettleman Hills, Kern 
County, California ; depth 5,465-5,484 feet. Reef Ridge shale, 
upper Miocene. Width 0.23 mm ; height 0.37 mm. Side view. 

Fio. 67-25. Bolivina sp. Same specimen as figure 67-24. 
Apertural view. 

Fig. 67-26. Nonionella miocenica Cushman. Hypotype, No. 
7754 (Calif. Acad. Sci. Paleo. Type Coll.). From Associated Oil 
Co., Watson well No. 1, Sec. 34, T. 22 S., R. 18 E., M. D., Kings 
County, California ; depth 5,805-5,818 feet. Reef Ridge shale, 
upper Miocene. Width 0.24 mm ; height 0.32 mm. Ventral view. 



Fig. 67-27. Nonionella miocenica Cushman. Same specimen 
as figure 67-26. Apertural view. 

Fig. 67-28. Nonionella miocenica Cushman. Same specimen 
as figure 67-26. Dorsal view. 

Fig. 67-29. Nonion, sp. Hypotype, No. 7755 (Calif. Acad. 
Sci. Paleo. Type Coll.). From Associated Oil Co., Watson well 
No. 1, Sec. 34, T. 22 S., R. 18 E., M. D., Kings County, Cali- 
fornia ; depth 5,805-5,818 feet. Reef Ridge shale, upper Miocene. 
Width 0.36 mm ; height 0.53 mm. Apertural view. 

Fig. 67-30. Nonion, sp. Same specimen as figure 67-29. 
Side view. 

Fig. 67-31. Bulimina ovula d'Orbigny. Hypotype, No. 7756 
(Calif. Acad. Sci. Paleo. Type Coll.). From Associated Oil Co., 
Whepley well No. 1, Sec. 35, T. 21 S., R. 17 E., M. D., Fresno 
County, California; depth 5,465-5,484 feet. Reef Ridge shale, 
upper Miocene. Width 0.30 mm ; height 0.48 mm. Side view. 

Fig. 67-32. Vvigerina cf. senticosa Cushman. Hypotype, No. 

7757 (Calif. Acad. Sci. Paleo. Type Coll.). From Aliso Canyon, 
Ventura County, California. Pliocene. Length 0.55 mm ; width 
0.35 mm. Side view. 

Fig. 67-33. Discocyclina clarki Cushman. Hypotype, No. 

7758 (Calif. Acad. Sci. Paleo. Type Coll.). From Domengine 
Reef on Domengine Creek, near center of Sec. 30, T. 18 S., R. 15 
E., M. D., Fresno County, California. Eocene. Greatest diam- 
eter 3.9 mm. 

Fig. 67-34. Bolivina interjuncta Cushman. Hypotype, No. 

7759 (Calif. Acad. Sci. Paleo. Type Coll.). From Lomita quarry, 
Palos Verdes Hills, Los Angeles County, California. Pleistocene. 
Length 0.95 mm ; width 0.35 mm. Side view. 

Fig. 67-35. Bolivina spissa Galloway and Wissler. Hypo- 
type, No. 7760 (Calif. Acad. Sci. Paleo. Type Coll.). From Pacific 
Western Oil Co., Rubel well No. 16, Sec. 8, T. 2 S., R. 14 W., 
S. B., Los Angeles County, California ; depth 1,125 feet. Pico for- 
mation, lower Pliocene. Length 0.85 mm ; width 0.30 mm. Side 
view. 

Fig. 67-36. Siphogenerina transversa Cushman. Hypotype, 
No. 7761 (Calif. Acad. Sci. Paleo. Type Coll.). From east side 
of Adobe Canyon, a quarter of a mile north and an eighth of a 
mile east of the southwest corner, Sec. 30, T. 27 S., R. 29 E., 
M. D., Kern County, California. Lower Temblor formation, Mio- 
cene. 

- Fio. 67-37. Riphogenerinoides whitei Church, n. sp. Holotype, 
No. 7762 (Calif. Acad. Sci. Paleo. Type Coll.). From near center 
of Sec. 6, T. 15 S., R. 12 E., M. D., Panoehe Hills, Fresno County, 
California. R. T. White, coll. Eight hundred feet below top of 
Moreno shale, upper Cretaceous. Length 2.25 mm ; width 0.75 
mm. Side view. (For description of this form, see accompanying 
paper by C. C. Church.) 

Fig. 67-38. Bolivina angelica Church. Hypotype, No. 7763 
(Calif. Acad. Sci. Paleo. Type Coll.). From Petroleum Securities 
Co., Mills well No. 1, See. 13, T. 6 S., R. 11 W., S. B., Hunting- 
ton Beach, Los Angeles County, California ; depth 2,820 feet. 
Repetto formation, lower Pliocene. From type lot. Length 1.05 
mm ; width 0.40 mm. Side view. 

Fio. 67-39. Bulimina subacuminata Cushman and Stewart. 
Hypotype, No. 7764 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Aliso Canyon, Ventura County, California. Pliocene. Length 
0.40 mm ; width 0.25 mm. Side view. 

Fig. 67-40. Bulimina rostrata H. B. Brady. Hypotype, No. 
7765 (Calif. Acad. Sci. Paleo. Type Coll.). From Aliso Canyon, 
Ventura County, California. Pliocene. Length 0.40 mm ; width 
0.25 mm. Side view. (See Cushman, Stewart, and Stewart 30a, 
p. 65, pi. 5, fig. 1.) 

Fig. 67-41. Valvulineria californica Cushman. Hypotype, 
No. 7766 (Calif. Acad. Sci. Paleo. Type Coll.). From Quailwater 
Creek, Sec. 24, T. 28 S., R. 14 E., M. D., 7.8 miles east of Creston, 
San Luis Obispo County, California. Lower Monterey shale, Mio- 
cene. Greatest diameter 1.45 mm. Dorsal view. 

Fig. 67-42. 31 arginulina vacavillensis Hanna. Hypotype, No. 
7767 (Calif. Acad. Sci. Paleo. Type Coll.). From 3 miles north 
of Vacaville, California, in bed of Ulatis Creek, southwest side of 
Dunn Peak. Capay or Domengine, Eocene. Length 1.10 mm; 
width 0.70 mm. Side view. 

Fig. 67-43. Vvigerina perigrina latalata Stewart and Stew- 
art. Hypotype, No. 7768 (Calif. Acad. Sci. Paleo. Type Coll.). 
From Aliso Canyon, Ventura County, California. Pliocene. 
Length 0.75 mm ; width 0.45 mm. Side view. 



Characteristic Fossil s— H anna and Hertlein 



181 




Fio. 67 (1 to 49). Foraminifera (Cretaceous to Pliocene) of California. (Microscopic fossil animals with calcareous tests). 



182 



Paleontology and Stratigraphy 



[Chap. VI 



Fro. 67-44. Uvigerina tenuistriata Reuss. Hypotype, No. 
7760 (Calif. Acad. Sci. Paleo. Type Coll.). From Aliso Canyon, 
Ventura County, California. Pliocene. Length 0.85 mm ; width 
0.30 mm. Side view. 

Fig. 67-45. Bolivina interjuncta Cushman. Hyoptype, No. 

7770 (Calif. Acad. Sci. Paleo. Type Coll.). From Aliso Canyon, 
Ventura County, California. Pliocene. Length 0.80 mm ; width 
0.30 mm. Side view. 

Fig. 67-46. Eponides tenera H. B. Brady. Hypotype, No. 

7771 (Calif. Acad. Sci. Paleo. Type- Coll.). From Aliso Canyon, 
Ventura County, California. Pliocene. Width 0.55 mm. Dorsal view. 

Fig. 67-47. Plcctofrondicularia jenkinsi Church. Hypotype, 
No. 7772 (Calif. Acad. Sci. Paleo. Type Coll.). From Markley 



Canyon (old quarry) NE} Sec. 2, T. 1 N., R. 1 E., M. D., Contra 
Costa County, California. Kreyenhagen shale. Eocene. Part of 
type lot. Length 1.50 mm; width 0.25 mm. Side view. 

Fig. 67-48. Plectofrondicularia californica Cushman. Hypo- 
type, No. 7773 (Calif. Acad. Sci. Paleo. Type Coll.). From Lo- 
mita quarry, Palos Verdes Hills, Los Angeles County, California. 
Repetto formation, lower Pliocene. Length 4.10 mm ; width 0.65 
mm. Side view. 

Fig. 67-49. Plectofrondicularia californica Cushman. Hypo- 
type, No. 7774 (Calif. Acad. Sci. Paleo. Type Coll.). From Lo- 
mita quarry, Palos Verdes Hills, Los Angeles County, California. 
Repetto formation, lower Pliocene. Length 2.10 mm ; width 0.35 
mm. Side view. 



DESCRIPTIONS OF FORAMINIFERA 

By C. C. Church* 



INTRODUCTION 

In connection with a series of papers on the Kreyen- 
hagen formation published by the California State Divi- 
sion of Mines in 1931 (Jenkins, 0. P. 31), the present 
writer included (Church, C. C. 31b), among others, 
figures of four characteristic Foraminifera which were 
believed then to have been undescribed, for which new 
names were supplied in the explanations of the plates. 
Formal descriptions of these forms, prepared at that 
time, are given below. In addition to these there is 
included a formal description of Siphogcncrinoides 
whitei; the illustration of this form appears on the plate 
of Foraminifera supplied by Messrs. Hanna and Hert- 
lein herewith. 

DESCRIPTIONS 

Plectofrondicularia jenkinsi Church, n. sp. 
Fig. 67-47 

Plectofrondicularia jenkinsi Church, n. sp. Rept. Calif. State 

Mineral., Vol. 27, no. 2, April, 1931, p. 208, pi. A, figs. 5, 7-9. 

This very distinctive species is elongate, compressed and rather 
uniformly narrow; edges smooth, rounded and slightly irregular; 
early arrangement of chambers gives the initial end a bluntly 
rounded aspect with a slight tendency to coiling ; first four or five 
chambers biserial, then regularly uniserial becoming inflated in 
the later stages, often growing rounded, triangular or square; ten 
chambers comprise the uniserial portion of the type which is a 
fair average; sutures somewhat depressed, visible as opaque lines 
outlining the more translucent chambers, regularly curving down- 
ward to the sides in inverted "V's" ; wall relatively thin, calcare- 
ous, translucent to glassy, finely perforate, polished, with minute 
striatums running longitudinally ; aperture terminal, oval to 
rounded, smooth outwardly but serrated with fine marginal teeth 
inside. Length 1.3 mm., width 0.18 mm. Named for Olaf I 1 . 
Jenkins, Chief Geologist, California State Division of Mines. 

The tendency of this species to change from the compressed 
to the inflated round, triangular or square form in growth led the 
writer to classify it at first as an Amphimorphina. It is con- 
sidered to be an excellent marker fossil for the Kreyenhagen. 

Holotype, No. 5502 (Calif. Acad. Sci. Paleo. Type Coll.) . From 
an old quarry 2J miles south of Antioch, Contra Costa County, 
California, NE} Sec. 2, T. 1 N., R. 1 E., M. D. 

Planularia markleyana Church, n. sp. 

Planularia markleyana Church, n. sp., Rept. Calif. State Mineral., 
Vol. 27, no. 2, April, 1931, p. 20S, pi. A, fig. 0; pi. B, figs. 1, 10. 
Test large, compressed laterally, chambers twelve or more, 
periphery smoothly rounded with only slight inflation of the cham- 
bers ; the initial chamber unusually large in the megalospheric 
form, standing out as a central nob; the smaller initial chambers 
of the microsphere form result in a greater number of chambers, 
a narrower test and a consequent elongation in the later uncoiled 
stage; chambers only slightly inflated over test, sutures plain, 
liinbate in the initial stages, depressed somewhat in the later, wall 



• Paleontologist, Tide Wafer Associated Oil Company. Manu- 
script submitted for publication December 2, 1940. 



thin, polished and smooth, very finely perforate, aperture a rounded 
opening with a short, cylindrical neck at the peripheral angle of 
the apertural face, short tooth-like irregularities serrate the edge 
suggesting a degenerate radiate opening. Length of type 1.2 mm, 
width .85 mm. Megalospheric form. 

Holotype, No. 5500 (Calif. Acad. Sci. Paleo. Type Coll.) . From 
Loc. 1832 (C. A. S.), Markley (Kreyenhagen) formation, 2\ miles 
south of Antioch, Contra Costa County, California, in an old 
quarry ; NE} Sec. 2, T. 1 N., R. 1 E., M. D. A good marker 
fossil. 

Pullenia lillisi Church, n. sp. 

Puilenia lillisi Church, n. sp., Rept. Calif. State Mineral., Vol. 27, 

no. 2, April, 1931, p. 208, pi. A, fig. 10. 

Test very small and compressed, five chambers visible, increas- 
ing enormously as they advance, the last three making up most of 
test, moderately inflated, close coiled, involute, sutures plain, 
depressed, slightly curved, wall smooth, finely perforate, calcareous, 
aperture a low arched opening at the base of the apertural face. 
Length 0.3 mm ; width 0.22 mm. 

Holotype, No. 5503 (Calif. Acad. Sci. Paleo. Type Coll.). From 
Loc. 1832 (C. A. S.), Markley (Kreyenhagen) formation, 2$ miles 
south of Antioch, Contra Costa County, California, in an old 
quarry ; NE}, Sec. 2, T. 1 N\, R. 1 E., M. D. 

Itobulus uelchi Church, n. sp. 

Rooulus welchi Church, n. sp., Rept. Calif. State Mineral., Vol. 27, 

no. 2, April, 1931, p. 212, pi. C, figs. 13, 14. 

Test small, close coiled, with thin, narrow keel, chambers 
increase normally with growth but become more inflated and 
develop a distinct angular offset where they meet the earlier coil, 
sutures indistinct in early part of coil but become pronounced 
depressed lines with increasing curvature, in the later chambers, 
wall calcareous, fairly thin, polished, finely perforate, no surface 
ornamentation, aperture radiate with facial opening larger and 
elongate, apertural face flattened and forming distinct angle with 
side, often continuous to two previous chambers. Rarely abundant 
but persistent and widespread , a good marker for the lower 125 
to 150 feet of the Kreyenhagen. 

Holotype, No. 5522 (Calif. Acad. Sci. Paleo. Type Coll.) . From 
Salt Creek, Fresno County, California, 125 to 150 feet above the 
base of the Kreyenhagen. Length 0.5 mm ; width 0.3 mm. 

Siphogenerinoides xchitei Church, n. sp. 
Fig. 67-37 

Test elongate, slightly tapering ; circular in cross section, 
widest at apertural end, early stages triserial in microspheric form, 
biserial in megalospheric form, uniserial in adult. Chambers dis- 
tinct but only slightly inflated, somewhat overlapping; sutures 
well marked, slightly indented scalloped lines in upper two-thirds 
of test, becoming faint dots in initial portion. Megalospheric form 
sides nearly parallel, initial end rounded and blunt; microspheric 
form pointed and tapering; wall minutely perforate. Aperture 
terminal with distinct lip, one side convex, the other concave, end- 
ing in two inwardly projecting tooth-like prominences. Leugth 
2.25 mm; width .75 nun. Named for R. T. White. 

Holotype, No. 7702 (Calif. Acad. Sci. Paleo. Type Coll.) . From 
near center Sec. 0, T. 15 S„ R. 12 E., M. I)., Panoche Hills, Fresno 
County, California, about N00 feet below top of Moreno shale, 
Upper Cretaceous; R. T. White, coll. 






SYNOPSIS OF THE LATER MESOZOIC IN CALIFORNIA 



Hy Frank M. Axdf.kson * 



OUTLINE OF REPORT 

Page 

Introduction 18.'? 

The Knoxville series IS.'? 

The Shasta series 183 

The Chico series 18." 



INTRODUCTION 

The following outline of the later Mesozoic series in 
California has been prepared chiefly because of the 
interest now felt in these terrains for their possible con- 
tent of economic deposits in certain districts of their 
occurrence. This interest is not entirely of recent 
origin, but its recent revival calls for some consideration 
of the subject, which can be given better now than in 
the past. Interest now, as in the past, has come partly 
from the economic aspects of correlative deposits in 
other west coast regions outside of California, rather 
than from evidences of their value found in their 
environs here. Since correlations are best based either 
upon stratigraphic or faunal evidences, these features 
are stressed in the following notes and tables. By these 
means later Mesozoic strata may be traced from one 
area to another within the limits of the State itself, or 
far beyond these limits in other regions. 

The Moreno formation is of interest in all parts of 
the State, wherever it can be traced, even beyond the 
limits of California if it can be traced so far, because 
of the oil measures it contains in Fresno County. The 
usefulness and value of such correlations should be evi- 
dent to all, and when they can be made to yield practi- 
cal results, the academic aspects of stratigraphic cor- 
relations become translated into values to the State of 
another order, and are seen to be instruments of utility 
for searchers for mineral wealth. 

Since paleontological criteria for correlation are not 
commonly understood, these have been reduced to the 
minimum in the following tables, and only the more 
important, or better known molluscan types are given 
for each of the faunal zones. These are of use to those 
who know them, and they can be learned readily by all. 

THE KNOXVILLE SERIES 

The Knoxville series constitutes the highest sequence 
of Jurassic age known in California, or on the Pacific 
coast. It is best developed on the western side of the 
Sacramento Valley between Shasta and Xapa counties, 
but. it extends farther south in scattered tracts in the 
Coast Ranges as far as Santa Barbara County. It is 
almost wholly detrital in character, and consists of 
shales, sandstones, and conglomerates, the shales forming 
much of its lower and higher divisions; and sandstones 
and conglomerates, its middle division. Its thickest sec- 
tions are found in western Tehama County, where it 
attains a thickness of more than 16,000 ft. 

Farther south it diminishes to 15,000 ft., 14,000 ft., 
12.000 ft., and 9.000 ft., due largely to the drop of the 
sediments by their transporting currents, or to the over- 

* Honorary Curator. Department of Paleontology, California 
Academy of Sciences, San Francisco. California. Manuscript sub- 
mitted for publication December 21, 1939. 



lap of the Shasta series along the eastern margin of the 
Knoxville. 

The series is divisible into three somewhat equal 
groups of strata — lower, middle, and upper — each with 
its characteristic faunal assemblage. 1 

The series contains characteristic marine fossils of 
three dominant invertebrate types: ammonoids, belem- 
noids, and Aucellae, the latter being the more abundant 
in each of the three groups of strata, although each 
group of strata has its appropriate eephalopod types. 

The Knoxville series contains little of present known 
economic value, although small amounts of petroleum 
have been found in its lower beds, and scattered bodies 
of limestone and other rocks capable of being utilized 
for structural purposes, or for road building. Its con- 
glomerates are usually of hard, resistant rock types, and 
are readily accessible in many localities. 

THE SHASTA SERIES 

In California the Shasta series constitutes a great 
sequence of strata (sandstones, conglomerates and 
shales), that have an aggregate thickness varving locally 
from 2.000 ft. or less to more than 25.000 ft." It is well 
developed along the west border of the Great Valley, 
and in the Coast Ranges to the west, as far south as 
Santa Barbara County. 

"Where it is in contact with the Knoxville series, it 
is generally unconformable, but in various places it 
overlaps the latter and rests directly upon pre-Knoxville 
formations (earlier Mesozoic and Paleozoic). 

The Shasta series is divisible into two groups of 
strata, the Paskenta group below, and the Horsetown 
group above, each with its characteristic faunal assem- 
blages of marine invertebrates, including ammonoids, 
belemnoids, and other classes. 

Many of these have already been described and 
illustrated (Anderson. F.M. 38a), but other species, 
and even genera, remain to be described. 

No economic features of present importance are 
attached to either group of the Shasta series, although 
the lower group contains deposits of limestone that may 
sometime be utilized for structural purposes. Prospect 
wells have been drilled into the lower group in search of 
petroleum, but so far drilling has been without com- 
merciai results. 

THE CHICO SERIES 

The Chico series constitutes the latest sequence of 
Cretaceous deposits in California, and has the widest 
surface distribution of any of them. Within its known 
geographic spread it covers not less than 20,000 sq. mi. 
of surface, and much larger areas under cover of later 
terrains. In California its aggregate thickness exceeds 
28,000 ft., though not in any single section. It is 
divided into three distinct groups of strata, not of equal 
thickness, or of equal surface exposure, as follows : 

The lowest, or Pioneer group, is restricted in its 
occurrence, but outcrops along the west side of the 
Sacramento Valley in a belt of considerable width, and 



1 Anderson. Frank M. The Knoxville series in the California 
Mesozoic : in pnss Geological Society of America. 



184 



Paleontology and Stratigraphy 



[Chap. VI 







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Oxytropidoceras packardi Anderson Acanthoplites perrlnl Anderson 

Beaudanticeras brewerl Gabb Douvllleiceras mammilatum var. 

Desraoceras merrlami Anderson SchJLotheim 

Sonneratia stantoni Anderson Cheloniceras stollczkanum Gabb 

Cleonlceras lecontal Anderson Puzosia dllleri Anderson 



Lytoceras bates! Trask 
Desmoceras voyi Anderson 
Melchlorites shastensis Anderson 



Phylloceras aldersoni Anderson 
Hamitlceras aequlcostatura Gabb 



Acroteuthis aborlginalis Anderson Parahoplltoides shoupi Anderson 
Gabbloceras angulatum Anderson Shastoceras shastense Anderson 



Ancyloceras elephas Anderson 
Ancyloceras ajax Anderson 
Shasticrloceras ponlente Anderson 



Neocraspedites aguila Anderson 
Hoplocrioceras remondi Gabb 



Shasticrloceras hesperum Anderson 
Pulchellia popenoel Anderson 
Hemibaculltes sp. 



Acroteuthis sp. 

Phylloceras occldentale Anderson 



DEPOSITIONAL HIATUS 



Local conglomerates . 






Polyptychites lecontel Anderson 
Simblrskltes broadi Anderson 
Lytoceras aulaeum Anderson 
Crioceras latum Gabb 



Inoceramus ovatus Stanton 



Neocomltes russelll Anderson 

Neocomites sp. 

Spitlceras duncanense Anderson 



Phylloceras sp. 
Berrlasella storrsl Stanton 
Aulacosphlnctes sp. 
Substeueroceras sp. 



Subastieria sp. 
Acroteuthis impressa Gabb 
Acroteuthis shastensis Anderson 



Hoplocrioceras sp. 



Lytoceras sp. 

Crioceras aff . latum Gabb 

Lytoceras saturnale Anderson 



Cylindroteuthis tehamaensls 

Stanton 
Cylindroteuthis sp. 
Inoceramus sp. 
Pecten sp. 



Dark clay shales. 



Dark sandy shales. 






Many beds of sandstone with occasional conglomerates; 
few fossils. 
Phylloceras sp. Kossmatla dillerl Stanton 

Rhynchonella schuchertl Stanton Aucella terebratuloides Lahusen 



Heavy beds of conglomerate and sandstone with few fossils. 



Sandy shales with few fossils. 



Kossmatia sp. 
Aucella piochii Gabb 
Aucella mosquensls von Buch 



Aucella sp. 
Belemnopsis sp. 



Dark concretionary 
shales; small 
amounts of gas, 
oil, tar. 



NEVADAN OROGENY 

MARIPOSA - MOUNT JURA SUCCESSION 



Fig. 68. 



Columnar section of the Knoxville series (Upper Jurassic) and the Shasta series 
(Lower Cretaceous) of California. 



Later Mesozoio — Anderson 



185 



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Turrltella sp. 
Pseudogaleodea sp. 
Glycymeris sp. 



Diplomoceras sp. 



Garzasaurus sp. 
Trigonarca sp. 



Baculltes occldentalls Meek 



Numerous diatoms and foramlnlfera Solenoceras 
Helicoceras Plesiosaurs 



Bostrychoceras aff. polyplocum Inoceramus aff. impressus 
Roemer d'Orbigny 



Parapachydiscus catarinae Anderson Lytoceras coallngense Anderson 
and Hanna n Hamites n vancouverensis Gabb 

Parapachydiscus pensularis Nostoceras sp. 
Anderson and Hanna Bostrychoceras sp. 

Desmoceras (KotOceras) fresnoense Tessarolax sp. 

Anderson Nemodon vancouverensis Meek 



Oil and gas in 
Fresno County. 



Phylloceras gargantuum Anderson 
Parapachydiscus panochensis 

Anderson 
Canadoceras aff. multicostatum 

Whiteaves 
Parapachydiscus sp. 



Inoceramus aff. sachallnensis 

Sokolow 
Inoceramus pacificus Anderson 

and Hanna 
Inoceramus aff. regularis 

d'Orbigny 



Canadoceras fraternum Gabb 
Trigonia hemphilll Anderson 
Mortoniceras aff. delawarense 

Morton 
Submortoniceras gabbi 

Anderson 



Submortoniceras buttense 

Anderson 
Submortoniceras chicoensis Trask 
Baculites chicoensis Trask 
Helicoceras breweri Gabb 
Munierlceras pentzanum Anderson 



Nowakites aff. carezi Grossouvre 
Canadoceras newberryanum Meek 
Parapachydiscus arbucklensis 
Anderson 



Inoceramus aff. 

Sowerby 
Inoceramus aff. 

Roemer 



digitatus 
undulatopllcatus 



Inoceramus pembertonl Vraring 
Desmoceras aff. pyrenalcum 

Grossouvre 
Desmoceras yoloense ^nderson 
Prionocycloceras crenulatum 

Anderson 
Placenticeras paciflcum Smith 
Peronlceras tehamaense Gabb 
Peronlceras sp. 



Possible oil- 
bearing beds. 



Conglomerates with Bellavista fossils. 



Prionotropis bakeri Anderson 
Prionotropis brannerl Anderson 
Gaudryceras tenuillratum Yabe 
Oregoniceras oregonense Anderson 
Oregoniceras knlghteni Anderson 



Phylloceras velledae Mlchelln 

Lyelliceras lyelll d'Orbigny 
Cyrtochllus aff. baculoldes 

d'Orbigny 
Pervlnqulerla inflata var. 

Cowerby 



Scaphltes condoni Anderson 
Scaphltes roguensis Anderson 
Fagesia callfornica Anderson 
Fagesla sisklyouensis Anderson 



Puzosia aff. planulata Sowerby 

Acanthoceras turneri White 
Stollczkala aff. clavlgera 

Neumayr 
Puzosia sp. 



Llgnitlc veins with 
concholaal fracture . 



Conglomerates with Alblan fossils. 



DEPOSITIONAL HIATUS 
Fig. 6:». Columnar section of the Chico series (Upper Cretaceous) of California. 



186 



Paleontology and Stratigraphy 



[Chap. VI 



farther north in Siskiyou County; it is not known to 
exceed 7,000 ft. in thickness at any place. This group 
constitutes the "lower Chico" division of earlier papers, 
and is characterized by an assemblage of marine fossils, 
gastropods, pelecypods and cephalopods, not all of 
which are yet well known, although they are now being 
described. 

The second division of the series, in stratigraphic 
order, -is the Panoche group. In thickness and in 
surface exposures this group far exceeds the preceding, 
and in its surface spread overlaps all older Cretaceous 
deposits unconformably. The Panoche is more than 
twice as thick as the Pioneer group, which in many areas 
is entirely covered by it. It embraces most of the 
"upper Chico" of earlier works, and includes all of the 
Cretaceous outcrops known on the east side of the 
Great Valley south of Shasta County (Chico Creek, 
Butte Creek, Pentz, Folsom, etc.), and most of the 
upper Cretaceous deposits exposed on the west side of 
the valley south of Tehama County. On the west side 
of the San Joaquin Valley, and in many other areas in 
the Coast Ranges west and south of this valley (Salinas 
Valley, Santa Maria Valley, Santa Ynez Valley, Santa 
Monica Mountains, Santa Ana Mountains, and San 
Diego County), this group of the Chico series is exten- 
sively spread, and assumes a major importance. 

Throughout its geographic extent the Panoche group 
contains its own assemblage of marine fossils, mostly 
distinct from those of the Pioneer group. Most of the 
larger ammonoids of the Pacific coast Cretaceous are 
found in the upper part of the Panoche group. Most 
of the coal mined on Vancouver and adjacent islands 
is from strata of this group, and in northern California 
(Siskiyou and Shasta counties) coal is found in rocks 
of this age, but not always in commercial quantities. 
Gas has also been obtained from strata of this group in 
many places (Siskiyou, Tehama, Sutter and Glenn 
counties). 

The highest division of the Chico series, the Moreno 
group, is more restricted in its occurrence, and is much 
less thick. Its greatest development is on the west side 
of the San Joaquin Valley, where it attains a thickness 
of 5,000 ft. or more, including three distinct stages 
(Moreno, Quinto, Garzas). 




The lowest, of these stages, the Moreno shale, is 
traceable from Coalinga northward to near Martinez, 
but it is not known to outcrop farther north. It is 
noted for having been the source of commercial quan- 
tities of petroleum a few miles north of Coalinga, and 
under suitable structural conditions it may also prove 
productive at other points. The upper part of the 
Moreno shale is highly organic in character, containing 
foraminifera. diatnmaceae, many forms of mollusks, and, 
in addition, bones of plesiosaurs and shore dinosaurs. 
In age it may be classed as uppermost Cretaceous, 
correlative with the Maestrichtian of southwest Prance 
or western Germany. This stage is overlaid by the 
Quinto member of the group, chiefly noted for its dis- 
tinctive molluscan fauna. This member has been traced 
at intervals from Los Banos Creek northward to Brent- 
wood, Contra Costa County. 

The highest part of the Moreno group, the Garzas 
member, is notable chiefly as being near the top of the 
Cretaceous succession, and the near equivalent of the 
Danian division of the upper Cretaceous in western 
Europe, and therefore, as constituting the highest beds 
of the Cretaceous system found on the west coast. 

It has yielded a distinctive fauna of marine mol- 
lusks, including species of Glycymeris, Trigonarca, 
Inoceramus, Erngyra, Turritella, Psrurlogaleodea, and 
various cephalopods. 

This member has a thickness limited to a few hun- 
dred feet, and is chiefly composed of fine or coarse 
sandstone, and of thin beds of conglomerate. It is 
unconformably overlain by marine Eocene beds that 
cover the Mesozoic sequence in many parts of California 
within, and outside the Great Valley. Among the fossil 
remains that have been found in this member is a 
species of saurian to which the name Garzaxaurus has 
been given by C. L. Camp of the University of 
California. 

The Moreno group contains oil and gas measures of 
economic consequence, that, under structural conditions 
suitable for accumulation and retention, have yielded 
these products in the past, and are still capable of 
doing so. 

The gas fields near Tracy, on McDonald Island, 
and at other places, seem to derive their gas supply 
from some part of the Moreno group. 



Fig. 70. Basal conglomerate of the Lower Cretaceous Shasta 
series. In the matrix are fossils characteristic of these rocks. 
The large, white, irregular limestone boulders carry fossils of the 
underlying Knoxville (Upper Jurassic). Location : Glenn County, 
near road between Chrome and Newville. Photo by Olaf P. 
Jenkins. 




Fie. 71. Typical Knoxville (Upper Jurassic) shales. Blue 
Canyon, north of Paskenta, Tehama County. Photo by Olaf P. 
Jenkins. 



NOTES ON CALIFORNIA TERTIARY CORRELATION 



By Bruce L. Clark * 



OUTLINE OF REPORT 

Page 

Introduction 187 

Paleoeene 187 

Martinez stage 187 

Eocene 187 

Meganos stage ;. 187 

Middle Eocene 187 

Capay stage 187 

Domengine stage 188 

Transition zone 188 

Tejon stage 188 

Oligocene 188 

Lower and middle Miocene 188 

Upper Miocene 190 

Pliocene 190 

Pleistocene 191 



INTRODUCTION 

This paper presents a brief outline of the divisions 
of the marine Cenozoic series of California, based upon 
the megafossils. Accompanying the report is a tentative 
correlation chart for some of the more important general 
areas; lack of space prohibits the discussion of details 
of the sections. There are several debatable points 
in this chart ; some of these pertain to nomenclature, 
others to local and general correlations. For example, 
the writer is not certain where the lines of division 
should come between the Eocene and Oligocene or the 
Oligocene and the Miocene. R. M. Kleinpell (38) places 
the Vaqueros and the lower portion of the Temblor (as 
here used) in the Oligocene. R. A. Stirton (37, 39) 
considers that the upper portion of the San Pablo group 
is lower Pliocene; Kleinpell (38), the writer, and others 
place it in the upper Miocene. 

PALEOCENE 
Martinez Stage 

The deposits here referred to the Paleoeene are 
designated generally as the Martinez formation, and 
have been placed in the Martinez stage by Clark and 
Yokes (36). The stage may be referred to as the Turri- 
tella. iiaeheeoensis zone. 

H. G. Schenck has pointed out, in an unpublished 
paper read before the meetings of the Pan American 
Scientific Societies at Berkeley in 1939, that the type 
section of the Martinez includes deposits which repre- 
sent at least a portion of the Meganos, Capay, and 
Domengine stages. The writer favors the restriction of 
the name Martinez to the lower part of this section; it 
is the fauna from these beds that has been referred by 
paleontologists to the Martinez. 

Important papers that deal with the faunas of the 
Martinez stage are those by R. E. Dickerson (14) and 
R. N. Nelson (25). Undoubtedly, however, only a small 
portion of the Martinez faunas is known and described. 



* Associate Professor of Paleontology, University of California, 
lerkeley, California. Manuscript submitted for publication July 
8. 1940. The writer is Indebted to Miss Herdis Bantson of the 
luseum of Paleontology, University of California, for aid in edit- 
ig the paper. Assistance in the preparation of this manuscript 
""•sonnel of Works Projects Administra- 
tes, 3-30, Unit A-l. 



Berkel 

2S. . 

Muse.... 

ing the pape; . 

was furnished also by the per 

tion. Official Projects Xo. 6<>" 



Dickerson (14) recognized three faunal zones in the 
"Martinez" formation; the Meretrix dalli zone, the 
Trochocyathus zittclli zone and the Solen stantoni zone. 
The first two only belong to the Martinez in the 
restricted sense, and their relative importance is still to 
be determined. 

EOCENE 

The Eocene series of California, on the basis of mega- 
fossils, is divided into four major zones or stages. 
These may be referred to as the Meganos, Capay, 
Domengine, and Tejon stages. A fifth division, the 
"Transition Zone" of Clark and Vokes (36), possibly 
should be included as a major zone. 

Meganos Stage 

The Meganos was differentiated and described first 
from a section north of Mt. Diablo, California (Clark, 
B.L. 18a). The fauna and stratigraphy of the forma- 
tion were described by Clark and Woodford (27), who 
recognized five divisions: A, B, C, D, and E, with a 
maximum thickness of about 3,000 ft. for the series'. 
The megafauna described from Division D came from a 
sandstone 300 ft. thick, about 1,000 ft. above the base of 
the section. 

On the basis of foraminifera, micropaleontologists 
consider that Division E of the type section of the 
Meganos belongs to the Capay stage (lower middle 
Eocene). In so far as the writer is aware, good fora- 
miniferal faunas have not been obtained from the lower 
portion of Division E. If there is a stratigraphic break 
between the deposits of Division E and those of Divi- 
sion D, it comes probably in the lower part of Division E. 

The fauna from Division D of the Meganos is cor- 
related with that found in the upper portion of the 
Santa Susana formation of Simi Valley, Ventura County, 
California. The same zone has been recognized in 
Round Vallev, Lake Countv, bv Merriam and Turner 
(37). 

MIDDLE EOCENE 

Clark and Vokes (36) have pointed out that there 
has been some confusion in the past as to the divisions 
here referred to the middle Eocene. For the history of 
the development of the concepts held at the present time, 
the reader is referred to their paper. 

Capay Stage 

The type section of the Capay formation lies on 
the west side of Capay Valley, several miles north of 
the town of Capay, Yolo County. These deposits con- 
tain the fauna of the Siphonalia sutterensis zone of R. 
E. Dickerson (14a, 16). This fauna, referred to the 
Capay stage (Clark and Yokes 361, has a wide geo- 
graphic distribution on the West Coast, and in places is 
divisible into several subzones (see Yokes, II. E. 39). 
Three of the most distinctive species of the Siphonalia 
sutterensis zone are Uahodca sutterensis Dickerson. 
Turritella merriam i Dickerson and Turritella andersoni 
Dickerson. At the present time a greater number of 
molluscan species are known from strata of this zone 



188 



Paleontology and Stratigraphy 



[Chap. VI 



than from any other portion of the Eocene and Pale- 
ocene on the Pacific Coast. 1 

Domengine Stage 

The deposits of the Domengine stage have a dis- 
tribution similar to those of the Capay. At a number 
of localities the Domengine deposits rest unconformably 
upon Capay strata. This is the case north of Mount 
Diablo and north of the town of Coalinga. The fauna 
of the Domengine is distinct from that of the Capay, but 
the two are fairly closely related, and many of the dis- 
tinctive species of the former have ancestral species in 
the older beds. A number of more generalized types 
are common to the two zones. 

Transition Zone 

The fauna referred by Clark and Vokes (36), to the 
"Transition Zone" should possibly be considered to 
belong to a subzone of the Domengine stage. The Rose 
Canyon shales, which form the upper portion of the 
La Jolla formation described by M. A. Hanna (27), are 
taken as the type section of this zone. The deposits 
may be referred to the Rimella supraplicata zone. 
Rimella supraplicata (Gabb) is ancestral to Rimella 
canalifera, a distinctive species of the Tejon stage. 
The fauna of this zone has been recognized at a num- 
ber of localities from the Mount Diablo area to southern 
California. There is no doubt as to its stratigraphic 
position between the deposits of the typical Domengine 
and those of the Tejon. The fauna of the "Transition 
Zone" has many more species in common with that of 
the typical Domengine than with the fauna of the 
overlying Tejon. 

Tejon Stage 

Until a comparatively few years ago, all the Eocene 
deposits of the West Coast (exclusive of those of the 
Martinez stage, here referred to the Paleocene) were 
referred to as Tejon. It was pointed out by Clark 
(Clark, B.L. 21, 26) that the type section of the Tejon 
formation came stratigraphically and unconformably 
above beds referable to the Domengine and Capay 
stages, and that the name Tejon should be restricted to 
these upper deposits, which contain a fauna distinct 
from that found in the underlying beds. Clark and 
Vokes (36) proposed the use of the term "Tejon stage" 
as a general designation for these deposits and faunas 
which can be correlated with the typical Tejon. The 
fauna of the type Tejon has been monographed by 
Anderson and Hanna (25). 

The deposits referable to the Tejon stage have a 
much more restricted distribution than do those of the 
Capay and Domengine stages. Clark and Vokes (36) 
have shown that three subzones are to be recognized in 
the type Tejon ; these are based upon subspecies of 



1 In the area north of Coalinga, deposits referable to the Capay 
stage were described by Vokes (3!)) and were referred by him to 
the Arroyo Hondo formation. Robert T. White (38) had already 
applied the name Lodo formation to these same deposits. White 
used the name Arroyo Hondo for one of the shale members in his 
Lodo formation. It should be noted, however, that the type section 
of the Lodo formation is north of the area studied by Vokes. and 
includes deposits referable to the Martinez stage as well as the 
Capay stage. In that area. Mr. White finds no evidence of a break 
between the deposits of these two stages. The Martinez deposits 
apparently are not present in the section studied by Vokes. White's 
names are used in the correlation chart accompanying this paper. 
It is the writer's opinion, however, that further stratigraphic and 
faunal work may show that the Martinez deposits should be 
included in a separate formation. (.See Vokes, H. E. 30; White, 
R. T. 38. 40.) 



Turritclla uvasa7ia Conrad. The Turritella uvasana 
group has been one of the most useful of all the gastro- 
pod species in the zoning of the Eocene strata. Species 
of the group appear first in deposits of the Martinez 
stage, and each zone of the Eocene has its distinctive 
subspecies. 

OLIGOCENE 

The Oligocene of western North America presents 
many unsolved problems. There is a possibility that 
certain deposits considered to be Oligocene, for example, 
the lower portion of the Gaviota formation of the 
Santa Ynez Mountains of California, should be referred 
to the upper Eocene. 

The faunal divisions of the marine Oligocene of the 
West Coast are best known from Oregon and Wash- 
ington. At least four major faunal zones are determin- 
able. These are, from base to top : the Keasey (Schenck, 
H.G. 27); Gries Ranch (Effinger, W.L. 38); Lincoln 
restricted (Weaver, C.E. 37) ; and Blakeley (Tegland, 
N.M. 33). All these zones have been recognized at 
one place or another in California. Thus the lower 
portion of the Gaviota formation and possibly the lower 
portion of the San Emigdio (Wagner and Schilling. 23) 
appear to be the equivalent of the Keasey, while the 
Gries Ranch zone is represented probably by the upper 
San Emigdio and a portion of the Gaviota. 

The megafossils from the lower portion of the Pleito 
formation (Wagner and Schilling. 23) show a close rela- 
tionship to those of the Lincoln formation (in the 
restricted sense) — i.e., the Molopophorus lincolnensis 
zone of Weaver. The fauna from the upper portion of 
the Pleito formation is equivalent to that found in the 
San Ramon formation- (Clark, B.L. 18). The latter 
fauna in turn appears to be close to that of the Blakeley 
of Washington. Kleinpell (38) on the basis of the fora- 
minifera, has expressed the belief that the Blakeley of 
Washington is the equivalent of the Vaqueros of Cali- 
fornia, and has placed it in the lower part of his Zemor- 
rian zone. The writer does not agree with this corre- 
lation. The megafaunas of the San Ramon and the 
Blakeley are more closely related to the fauna of the 
underlying Lincoln than to that of the overlying 
Vaqueros. In the San Emigdio Mountains the San 
Ramon fauna is found in the upper part of the Pleito 
formation, which lies unconformably below the 
Vaqueros. Thus, if the correlation of the San Ramon 
of California with the Blakeley of Washington is cor- 
rect, it is difficult to see how the latter fauna can be 
the equivalent of that of the California Vaqueros. 

LOWER AND MIDDLE MIOCENE 

In the correlation table, the writer has followed gen- 
eral usage and has placed the Vaqueros in the lower 
Miocene and the Temblor in the middle Miocene, 
although the use of "Temblor" for middle Miocene is 
questionable. Much work remains to be done on the 
molluscan faunas of the "Temblor" before the zones 
can be adequately differentiated. 

The megafauna of the Vaqueros has been described 
by Loel and Corey (32). It is more closely related to 
that of the overlying "Temblor" than to the fauna of 
the underlying San Ramon. Remington Kellogg 2 



2 Written communication. 



California Tertiary Correlatio n — C lark 



189 



GENERAL 
TIME SCALE 



COAST 



RANGES OF CALIFORNIA 



BERKELEY 
HILLS 



NORTH OF 
MT DIABLO 



SOUTHS WEST Of 
MT. DIABLO 



COALINGA 
AREA 



SOUTHERN SAN 
JOAQUIN VAL 



VENTURA CO 
S/MI VAL. AREA 



LOS ANGELES 
BASIN 



SAN DIEGO 
COUNTY 



I 



River terraces 



Terraces 



To/are 



Terraces 



Tu/are 



Terraces 



LasPceas, 



Saugus 



UPPER 



San Jos fun c«rs 



MIDDLE 



Tassa/ara 



Tassajara 



Etchegoin ss. 



LOWER 



Bale/ Peak /aras 

Siestan 
Morega vol. 



Los Mecfanos 
"Lanier turf 1 



Green ISa/Zey 
A/emo formation 



Jacalitos 

Reef Ridge 
scales 



Etchegoin 

(including 
San Joaouin c/tys) 



Jaca/ifos 




Palos vardes ' 
Upper San fbdm 
Lover San ftaefro 
Timms foint zone 
'San /hah) Pliocene' 



' San Pedro' 



3^ St. Tunnel 
af-e'r't Brdny 



San Diego zone 



San Diego zone 



Repetto 



Repetto 



UPPER 



Or/no's - f/ero/y 

Cierbo 
Briones rfercu/es 



Ifero/y 
Cierbo 



f/ero/y formation 

Cierbo SS 
Briones ss. 



Santa Margarita 

formation - 
MCLure sna/e 



Maricopa 



Mocfe/o " 



Puente 



MIDDLE 



Roc/eo sh 

ffambre ss 

Tice an 

Oursan ss 

C/aremont sh 

Sobranfe ss 



'Monterey ' 
formation 



Big B/ue ' 



Temblor' 



"Temblor' 



Topanga 



Topanga 



LOWER 



Kaqueros 
Teeuya 



Vaqueros 
Sespe 



Vaqueros 



UPPER 



Concorc/ ss 

fC/rker fuff 

San Ramon ss 



P/eito 



MIDDLE 



fCirker tuff 



rYirker SS 



San Ramon 
formation 



Tumey formation 



San Emigdio 



LOWER 



UPPER 



Markley fm. 

Upper Redio/erien 

zona 



"kreyenhagen 1 
proper 



Sespe 



Lower Sespe 



Tejon 



Tit/on . 



Potvay congl. 



MIDDLE 



Unctiff. Eocene. 



Norfonville sh " 
Loner Radio/arian 
zone 

"Domengine " 



Division £ 
Capay 



Canoas sift 



LOWER 



<5u 

J 2 



Domengine