Petroleum Potential of 

Wilderness Lands in 

California

By Edward W. Scott

PETROLEUM POTENTIAL OF WILDERNESS LANDS IN THE 

WESTERN UNITED STATES

GEOLOGICAL SURVEY CIRCULAR 902-D

This chapter on the petroleum 

geology and resource potential of 

Wilderness Lands in California is 

also provided as an accompanying 

pamphlet for Miscellaneous Investigations Series Map 1-1538

CONTENTS

Province 77 Santa Maria Basin 

Province 81 A Eastern California 

f^oQf^nfltf* A^n/^rv* Qiil'mi*mrin/*tfk

Transverse Ranges subprovince 

Imperial Valley subbasin 

Province 901 Santa Lucia Range 

(nlimlif'nt'ivA A^mliifii*irm rk^^xril^Av^n^aQ fliicrt^Y^Q

RflpH'pfl rpfiprpnrpn ,. . - -. _.._

Page

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5

5

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5

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7

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, , 12

ILLUSTRATIONS

Page 

FIGURE 1. Index map of California showing the USGS petroleum provinces as used by Dolton and others (1981) D3

2. Index map of California showing the geomorphic divisions of the Eastern California province (81 A) 6

3. Index map of California showing the USGS petroleum provinces and the 16 clusters of Wilderness Lands with

petroleum potential assessed in the State 8

4. Index map of California showing all the Wilderness Lands included in the analysis for petroleum resources 9

III

PETROLEUM POTENTIAL OF WILDERNESS LANDS IN THE WESTERN UNITED STATE?

Petroleum Potential of Wilderness Lands in California

By Edward W. Scott

ABSTRACT

California Wilderness Lands having oil and gas potential of 

varying degrees were grouped into 16 dusters, covering 11.596 

million acres. Their potentials range from a medium potential 

in a few small tracts in producing basins to very low potentials 

in terranes of mixed sedimentary and igneous and volcanic 

rocks in the eastern and northern parts of the State. All tracts 

outside of these clusters, 7.253 million acres of Wilderness 

Lands making up the total 18.849 million acres in the State, 

are assessed as having zero petroleum potential and are located primarily in igneous and volcanic terranes in the east and 

central portions of the State.

INTRODUCTION

California currently ranks fifth overall as a 

source of conventional petroleum in the United 

States. Through 1979 approximately 24 billion 

barrels of recoverable oil and 33 trillion cubic feet 

of natural gas had been discovered. Nearly all of 

the known recoverable oil and natural gas is in 

fields of significant sizes. Nearly 99 percent of the 

oil and 96 percent of the natural gas occur in 155 

fields. Fifteen giant fields have 63.4 percent of the 

oil and 52.6 percent of the natural gas (Nehring, 

1981).

All of the oil and gas fields discovered to date 

are in sedimentary basins either in the Great Valley or occupying re-entrants into the Pacific border provinces. Most of the rest of the State is underlain by igneous rocks, both lava and intrusive 

types; metamorphosed sedimentary rock; or 

metavolcanics (Landes, 1970).

The predominant trap types for the sigrificant 

oil and gas fields in California are anticlines or 

faulted anticlines that produce primarily from Tertiary sandstone reservoirs. There are a few 

sandstone reservoirs in fields producing from the 

Cretaceous in the Sacramento Valley ancf some 

small fields producing from the Jurassic.

Nearly 19 million acres of Wilderness Lards are 

in the State of California; these lands were 

evaluated in this study and lie within 511 separate 

wilderness polygons ranging in size from 4 acres 

to 700,000 acres. However, the majority of the 

Wilderness Lands fall outside of the known petroleum producing basins and occur most frec'iently 

in the igneous-metamorphic complexes of the 

northern and east-southeastern parts of the State.

A brief description of the regional geolofry and 

geologic history for the entire State of California 

is followed by a more detailed description of the 

geology and petroleum potential of the Wilderness 

Lands within the State.

REGIONAL GEOLOGIC HISTORY

California was part of a large geosynclir^ during most of the Paleozoic. This was initiated when 

an early Paleozoic sea advanced from the Pacific 

area eastward to the midcontinent. Maintain 

building in California started in the Late TriassicMiddle Jurassic part of the Mesozoic and culminated at the close of the Jurassic with the Nevadan orogeny.

Dl
The mountain-building processes continued into 

Late Cretaceous and included folding, faulting, 

and uplift, plus granitic intrusions and volcanic activity. The tectonic events during the Mesozoic resulted in the dominant relief of California of a 

parallel system of north-northwest trending mountain ranges with a long narrow valley between the 

ranges. This feature, the Great Valley of California, was a basin of deposition and received 

miogeosynclinal, clastic sediments during the 

period from Late Jurassic until early Pleistocene. 

The eastern mountain system includes the 

Klamath, Sierra Nevada, and Peninsular Ranges. 

The western mountain system is the Coast 

Ranges, with San Francisco Bay separating the 

North and South Ranges.

During the Late Jurassic-Early Cretaceous tectonic activities, a heterogeneous section of 

eugeosynclinal sediments and volcanics was being 

deposited in a trench at the base of the continental 

slope to the west of the present Coast Ranges. 

This is the Franciscan assemblage of California 

and the source of the sediments was the growing 

Sierra Nevada and Klamath Mountains.

At the time of Franciscan deposition, another 

major sedimentary sequence was being deposited 

in shallow seas on the shelf-slope. This is the 

Great Valley sequence which consists of about 

50,000 ft (15,240 m) of sandstones, shales, and 

conglomerates that were deposited under 

miogeosynclinal conditions and are present under 

the Great Valley of central California. Much of 

this section is exposed along the west side of the 

Sacramento Valley, the northern subbasin of the 

Great Valley.

A subduction zone developed under the Great 

Valley in mid-Jurassic time, and the Great Valley 

Series of rocks on the continental block was thrust 

many miles westward over the Franciscan oceanic 

plate rocks. This subduction and thrusting continued until mid-Oligocene time. The overthrust 

Great Valley sequence was folded, but little disturbed, whereas the underthrust Franciscan Complex has been described as a tectonic jumble and 

some of the rocks have been metamorphosed.

When the subduction and thrusting stopped in 

early Tertiary time (middle Eocene and Oligocene) 

the San Andreas fault system began to develop. 

The fault is still active and right-lateral displacement of 160 to 310 miles (256 to 496 km) has taken 

place since movement was initiated. The movement along the San Andreas fault has affected two

of the California provinces. On tin west side of 

the San Joaquin Valley, faulting ar 1 folding have 

developed structures both parallel and subparallel 

with the trace of the San Andrew, and similar 

features are present in the Coast Ranges to the 

east of the San Andreas fault.

In early Tertiary time, eoastH movements 

started in the Coast Ranges. Ther* was volcanic 

activity in the Coast Ranges during the middle 

Miocene followed by uplift and fold^*. The Coast 

Range orogeny culminated in late Pliocene into 

Pleistocene time.

Emphasis has been placed on mountain building 

in the discussion on California. The State is quite 

mountainous and the mountains and some major 

valleys form the basis for the des;<*nation of the 

various major geomorphic provinces that contain 

subprovinces or petroleum province* that were assessed for petroleum resources by the U.S. 

Geological Survey (Dolton and others, 1981).

Nine provinces, from Dolton anc1 others (1981), 

assessed for potential petroleum resources are 

73 Sacramento Basin; 74 San Joaquin Basin; 

75 Los Angeles Basin; 76 Ventr^a Basin; 77 

Santa Maria Basin; 78 Central Coastal Basins; 

79 Sonoma-Livermore Basin; 80 Humboldt 

Basin; and 81A Eastern Californr For the program of assessing petroleum potentials of the Wilderness Lands, two additional provinces have 

been added, 901 the Santa Lucia Range, and 

902 the Northern Coast Ranges.

Brief discussions on the geolopry of the provinces that contain Wilderness La^ds will follow, 

and the provinces will be treated in numerical 

order. Four petroleum provinces will not be discussed in this report because there are no Wilderness Lands within these provinces They are 73 

Sacramento Basin; 75 Los Angers Basin; 79 

Sonoma-Livermore Basin; and 80 Humboldt 

Basin.

CALIFORNIA PROVINCES 

SUMMARY OF GEOLOGY

California is divided into 11 petroleum provinces 

(fig. 1) based essentially on geomorphic outlines. 

These provinces encompass basins but they also 

include mountains and less prorrsing areas of 

basement and volcanic rocks. Most of the Wilderness Lands are located in the confines of the restricted limits of the basins. A brie* review of the 

geology of the provinces follows.

D2
124< 122* 120* 118e 116e 114°

42

40

38°

36

34

32'

CALIFORNIA 

ASSESSMENT PROVINCES

USGS PETROLEUM 

PROVINCES

73

74

75

76

77

78

79

80

SACRAMENTO BASIN 

SAN JOAQUIN BASIN 

LOS ANGELES BASIN 

VENTURA BASIN 

SANTA MARIA BASIN 

CENTRAL COASTAL BASINS 

SONOMA-LIVERMORE BASIN 

HUMBOLDT BASIN

81A EASTERN CALIFORNIA 

NOTE

PROVINCE 901 - SANTA LUCIA AND 

PROVINCE 902 - NORTHERN COAST 

KLAMATH RANGES ARE NOT 

PROVINCES AND WERE NOT 

ASSESSED BY USGS IN 1981

50 100 MILES

6 50 100 KILOMETERS

FIGURE 1. Index map of California showing the USGS petroleum provinces as used by Dolton and others (1981). The petroleum 

provinces in which Wilderness Lands in California are located are listed in the appendix of this circular.

D3
PROVINCE 74 SAN JOAQUIN BASIN

The San Joaquin Basin is the southern subbasin 

of the Great Valley of California that lies between 

the Sierra Nevada Mountains on the east and the 

Coast Ranges on the west. The San Joaquin subbasin is separated from the northern Sacramento 

subbasin by the Stockton arch, a subsurface feature.

The San Joaquin Basin is an asymmetric basin 

with a steep west flank and a gently sloping east 

flank. It is filled with up to 50,000 ft (15,240 m) 

(Oakeshott, 1978) of marine miogeosyclinal rocks 

that range in age from Late Cretaceous through 

the Pliocene.

There were many sediment sources around the 

periphery of the basin including the Sierra 

Nevada Mountains in the east, the Klamath Mountains to the north, and the Coast Ranges to the 

west. These various source areas, in conjunction 

with both regional and local uplift, have resulted 

in complex structural and stratigraphic conditions.

Oil and gas production is mainly from sandstone 

reservoirs that are present throughout the section 

from Upper Cretaceous through lower Pleistocene.

The dominant trap type in the San Joaquin 

Basin is anticlinal, but faulting and stratigraphy 

are very important, especially in the southern and 

southwestern parts of the basin where the majority of the fields are located. The unequal distribution of fields in the basin is shown by the fact that 

approximately 84 percent of the oil and 68 percent 

of the gas found in the basin to date are in the 

southern half.

PROVINCE 76 VENTURA BASIN

The Ventura Basin is part of the Transverse 

Ranges geomorphic province. The basin (fig. 1) as 

assessed includes the onshore Ventura Basin 

(Nagle and Parker, 1971) to the east and the onshore part of the Santa Barbara Channel Basin to 

the west. It is bounded on the north by the Santa 

Ynez fault, on the east by the San Gabriel fault, 

and on the south by the Santa Monica Mountains 

and the Pacific Ocean.

Over 50,000 ft (15,240 m) of sedimentary rocks 

lie along the Santa Clara trough in the central 

part of the basin. They range in age from Late 

Cretaceous through Pleistocene and all of the 

units have some oil production. By far the most 

prolific units, however, are the Pliocene (15,000 ft,

4,570 m) and upper Miocene (6,000 ft, 1,830 m). 

The province can be divided into several tectonic 

provinces, but the most important is the central 

east-west trending Santa Clara trough. This 

trough apparently began during la*e Miocene time 

with a downwarp of the basement, which created 

a deep depositional basin. The basin had several 

periods of minor downwarp and fr'Uting until the 

Pleistocene, which marked the onset of the 

Pasadenian orogeny. This orogeny, which continues to the present, is responsible for the physiographic features of the Ventura Pasin.

PROVINCE 77 SANTA MAI 'A BASIN

The Santa Maria Basin province is a triangular 

area in the southwest part of the State (fig. 1). It 

is bounded on the northeast by the NacimientoRinconada fault complex, on the south by the 

Santa Ynez fault in the Santa Ynez Mountains, 

and on the west by the Pacific Oce^n.

The area is floored by a Jurassic-Early Cretaceous basement complex of metasedimentary and 

igneous rocks. The main sedimentary Santa Maria 

basin has up to 15,000 ft (4,570 m) of Upper Cretaceous through Pleistocene rocks. The rocks from 

the Upper Cretaceous through th? lower Miocene 

are not evenly distributed. Subsidence occurred in 

the early middle Miocene, at whicl time there was 

a transgression of the sea and marine deposition 

continued until late Pliocene time.

Most of the production in the Ss nta Maria Basin 

is associated with structural trans, but a large 

percentage comes from stratigraphic traps of 

truncated sands and fractured si ales. Producing 

units range in age from fractured Jurassic and 

Cretaceous basement to lower Pliocene sands, but 

approximately 75 percent of the production is 

from fractured Monterey Shale of Miocene age.

PROVINCE 78 CENTRAL COASTAL BASINS

This province (fig. 1) is a small part of a large, 

north-northwest trending geomoi^hic province 

the Coast Ranges. This geomorpMc province lies 

between the Pacific Ocean and tH Great Valley. 

It extends from the Klamath Mountains on the 

north to the Santa Ynez Mountains of the Transverse Ranges on the south and r composed of a 

complex series of independent rar?es and valleys. 

Province 78 includes two of these valleys 

Cuyama and Salinas.

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Historically, in early Paleocene time, shallow 

seas crossed the western part of the State and 

there was a period of crustal quiescence during the 

Paleocene and Eocene. In late Eocene to early 

Miocene time, parts of the Coast Ranges were elevated above sea level. In the late part of the early 

Tertiary, crustal movements began in the Coast 

Ranges with different events in different ranges.

Middle Miocene time was the beginning of volcanic activity and large amounts of volcanic material are present in this part of the stratigraphic 

section. The Miocene closed with uplifting and 

faulting, and the Coast Range orogeny culminated 

in the late Pliocene to middle Pleistocene. There 

has been continued warping, faulting and vertical 

uplift during the Quaternary.

This Central Coastal province contains two 

major basins: the Salinas Valley to the north and 

the Cuyama Valley to the south. The Salinas Valley basin consists of two major features: (1) the 

Salinas trough, filled with nearly 20,000 ft (7,000 

m) of lower Miocene to Pliocene rocks, and (2) an 

eastern shelf with about 6,000 ft (1,829m) of 

upper Miocene and Pliocene rocks. The large San 

Ardo oil field is located in the eastern shelf and 

produces heavy oil (11 to 14 degrees API gravity) 

from upper Miocene sands in a large stratigraphic 

trap.

The Cuyama Valley Basin contains sedimentary 

rocks ranging in age from Upper Cretaceous to 

Pliocene with an estimated maximum thickness of 

about 6,000 ft (1,829 m). Four fields in this basin 

produce from lower Miocene sands with faulted 

anticlines being the major trapping mechanism.

PROVINCE 81 A EASTERN CALIFORNIA

This province is divided into eight subprovinces 

(fig. 2) on the basis of geomorphology. There are 

Wilderness Lands within each of the subprovinces 

and a brief geological summary is made for each.

CASCADE-MODOC SUBPROVINCI

This subprovince lies in the northeast part of 

the State (fig. 2) and is bounded on the north and 

east by the California State line, on the south by 

the Sierra Nevada Mountains, and on the west by 

the Klamath Mountains. The north-south trending 

Cascade Ranges form the western margin of the 

subprovince; the remainder of the province is 

covered by a thick accumulation of Cenozoic volcanic rocks of varying thickness with limited exposures of marine Cretaceous rocks and scattered 

Tertiary lake beds.

At least six wells have been drilled in th« area 

without any reported shows of oil or gas. TIT ere is 

only a small chance for any hydrocarbon potential 

in this subprovince. This slight chance is related 

to a few outcrops of marine Cretaceous rocvs and 

the presence of two inferred basins beneath the 

volcanic section.

SIERRA NEVADA SUBPROVINCE

This subprovince is a large block of Mosozoic 

granitic rocks having roof pendants of metanorphosed Paleozoic sedimentary rocks. The area is not 

considered to have any petroleum potential.

MONO-INYO SUBPROVINCE

This subprovince, like the Sierra Nevad^ subprovince, is essentially an area of granitic rocks 

that includes the Inyo batholith. No hydrocarbon 

potential is given to the area.

GREAT BASIN AND MOJAVE DESERT 

SUBPROVINCES

These two subprovinces are in southeastern 

California (fig. 2). They have a similar geoMgical 

setting and are characterized by north-northwest 

trending mountain ranges that alternate wHh intervening valleys and basins. The range^ are 

horsts and the basins are sediment-filled grabens. 

The boundary between the two subbasins is the 

Garlock fault and its eastward extension to the 

California State line.

The area was covered by marine Paleozoic rocks 

and later intruded by granitic batholiths during 

the Mesozoic orogenies. The Cenozoic rods are 

composed mainly of nonmarine lake and stream 

deposits with some evaporite deposits and volcanic rocks. There are a few limited aroas of 

marine Tertiary rocks along the Colorado River 

and adjacent to the San Andreas fault that offer 

very limited possibilities for petroleum.

TRANSVERSE RANGES SUBPROVINCE

The Transverse Ranges of California firm an 

east-west trending geomorphic unit that extends 

from Point Conception on the west to the eastern 

end of the San Bemardino Mountains in central 

southern California. The eastern part that forms 

the subbasin of the Eastern California province 

(81A) lies between the Mojave Desert and Imperial subprovinces (fig. 2).

D5
124< 122° 120* 118* 116° 114°

42 C

40 C

38 e

36 e

34'

50 100 MILES

50 100 KILOMETERS

32'

FIGURE 2. Index map of California showing the geomorphic divisions of the Eastern California province (81A).

D6
This part of the Transverse Ranges includes the 

San Gabriel and San Bernardino Ranges and is 

composed of Precambrian and Paleozoic metamorphic rocks and Mesozoic granites. The subprovince 

is not considered to have any potential for hydrocarbons.

IMPERIAL VALLEY SUBBASIN

This subbasin is in Southern California and lies 

between the Mojave and Peninsula Range subprovinces (fig. 2). It is a long, north-northwest trending graben bounded on the northeast by the San 

Andreas fault and on the southwest by the San 

Jacinto fault. The surface expression is an elongate topographic depression that is the northwest 

continuation of the Gulf of California.

The basin is filled with more than 20,000 ft 

(7,000 m) of late Cenozoic rocks (Oakeshott, 1978) 

that lie on Cretaceous granite and older metasediments. The oldest Cenozoic rocks are nonmarine, 

coarse elastics of Miocene age that are overlain by 

coarse, shallow-marine Pliocene rocks.

The subbasin is considered to have very poor 

source rock possibilities owing to the preponderance of nonmarine rocks and the "apparently 

sterile environments of the marine sediments" 

(Tarbet, 1971). This probably accounts for lack of 

any substantial shows of hydrocarbons in the wells 

drilled to date. The possibility of commercial accumulations of hydrocarbons is quite low.

PENINSULAR RANGE SUBPROVINCE

This geomorphic subprovince is in the southwestern part of California, between the Imperial 

Valley and the Pacific Ocean (fig. 2). It extends 

from the junction with the Transverse Ranges on 

the north to the Mexican border on the south.

There are two distinct geomorphic units in this 

subprovince: (1) an eastern mountainous area, and 

(2) a narrow coastal strip of sedimentary rocks. 

The eastern mountainous area is underlain by the 

mid-Cretaceous granite of the southern California 

batholith and metasedimentary rocks of Paleozoic 

and Mesozoic age. This part of the subprovince 

does not have any petroleum potential.

Sedimentary rocks occur in the narrow coastal 

strip and range in age from Upper Cretaceous 

through Pleistocene. The distribution is not uniform, especially from late Eocene through 

Pliocene, where outcrops are discontinuous along 

the coast. A large part of the sedimentary section 

is of marine origin and is considered to have some

petroleum potential in restricted areas.

More than 175 wells have been drilled in the 

Peninsular Range subprovince, and about 60 percent of these were drilled in the narrow coastal 

sedimentary strip. Two discoveries were reported 

prior to 1960 in the northern part of the coastal 

strip. Both were noncommercial one-weF fields 

and were abandoned after producing about 4,000 

barrels of oil and 11 million cubic feet of gag

PROVINCE 901 SANTA LUCIA RANC *

This province lies along the south-centrr.l coast 

of California between the central Coast Ranges 

province and the Pacific Ocean and to the rorth of 

the Santa Maria province (fig. 1). It is the Santa 

Lucia Range of the Coast Ranges. Most of the 

area is covered by the Jurassic-Cretaceous Franciscan metasedimentary complex and is nonprospective. There are a few areas of Cretaceous to 

Miocene rocks that offer only very slight possibilities for petroleum.

PROVINCE 902 NORTHERN COAST RANGES

This province covers, most of northvTestern 

California (fig. 1). The province consists essentially of the Jurassic-Cretaceous metanorphic 

complex that is considered nonprospective. There 

are small, local areas of Tertiary rocks, and oil 

seepages are known from a very young phase of 

the least metamorphosed part of the Franciscan 

that offers only slight chances for petroleum. A 

possible but extremely remote potential exists in 

the unaltered Paleozoic rocks beneath the Franciscan assemblage.

QUALITATIVE EVALUATION OF 

WILDERNESS CLUSTERS

For purposes of this report and the acco*npanying Miscellaneous Investigations Series Fap (I1538, in press), Wilderness Lands in California 

with oil and gas potential are grouped or subdivided into 16 clusters of geologically related appraisal areas (see fig. 3). These Wildernesr Lands 

with varying degrees of petroleum potential account for 11.596 million acres of the total 18.849 

million acres of Wilderness Lands in the State (fig. 

4). The remaining 7.253 million acres of Wilderness Lands have zero petroleum potential and are 

located primarily in igneous and volcanic rock terD7
124<

42

40'

38'

36'

34'

32° -

122*

 I 

120*

 I 

118*

 r 

116* 

 T~

114 e

 r~

WILDERNESS CLUSTER AR^AS

50 100 MILES

0 50 100 KILOMETERS

FIGURE 3. Index map of California showing the USGS petroleum provinces and the 16 clusters of Wilderness Lands with petroleum potential assessed in the State. The clusters are shown in a shaded pattern with the circled numbers and are discussed 

in the text. The petroleum provinces are listed in the appendix of this circular.

D8
120°

EXPLANATION 

C\ Outline of wilderness tracts

100 MILES

FIGURE 4. Index map of California showing all the Wilderness Lands induded in the analysis for petroleum resources The map 

is an example of a machine-plotted map produced from digitized wilderness data reduced from a 1:1,000,000 scale map (BLM, 

1981).

D9
ranes. The Wilderness Lands with zero potential 

are not included in the following discussion.

The presence or absence of possible source 

rock, reservoir rock, and trapping mechanisms 

were the most crucial factors used in qualitatively 

assigning a potential of medium, low, and low to 

zero oil or gas potential to each of the 16 clusters. 

An explanation of the geology within the areas of 

the respective wilderness clusters is briefly described by province along with the ratings of the 

petroleum potential within the areas of the Wilderness Lands.

Cluster 1 Province 74 Son Joaquin Basin

This cluster is located in the west-central part 

of the San Joaquin Basin province near the western limits of the San Joaquin Valley (fig. 3). The 

cluster consists of two tracts about 16 miles apart 

in a north-south direction.

The cluster lies within a petroliferous area, but 

the geological conditions of reservoir rocks and 

trapping mechanisms are not favorable for major 

hydrocarbon accumulations. An example of this is 

the Vallecitos oil field that lies between the two 

tracts. This field is a complex of 10 separate producing areas within a 40 square mile area. 

Maximum total productive area for the 10 units is 

360 acres. The estimated ultimate recovery is 5 

million barrels of oil and 5.5 billion cubic feet of 

gas.

Trapping mechanisms at Vallecitos are variable 

and include three faulted anticlines, one tar seal, 

and six stratigraphic traps that include both 

lithofacies changes and truncations. Production is 

from Paleocene and Eocene sands at depths ranging from 1,000 to 5,300 ft (305 to 1,615 m).

A second field, Cheney Ranch, lies about 16 

miles (25 km) to the east and down-dip from the 

cluster. This field produces gas from a Cretaceous 

sandstone at a depth of 7,000 ft (2,130 m) and the 

trapping mechanism is a sandstone pinchout 

(lithofacies change) on an east-dipping monocline. 

Estimated ultimate recovery is 4 billion cubic feet 

of gas.

The conditions of poor field quality as shown by 

the Vallecitos and Cheney Ranch fields, a low success rate in exploration drilling in this part of the 

San Joaquin Valley, and the location on the less 

prospective, western edge of the basin are the 

basis for a low to medium rating for the cluster.

Clusters 2, 3, and 4 Provinces 76 Venture, 

77 Santa Maria, and 78 Central Coastal Basins

Clusters 2, 3, and 4 include a concentration of 

Wilderness Lands that is grouped around the common corner of the three provinces, Ventura, Santa 

Maria, and Central Coastal Basins (fig. 3). This 

grouping is located in a mountainous area that 

roughly coincides with the junction of the Santa 

Ynez Mountains of the Transverse Ranges and the 

Sierra Madre Mountains of the Southern Coast 

Ranges.

This area has geological conditions that persist 

over most of this part of the region and that are 

quite different from the conditions in the respective basins of these provinces. Brie%, the area of 

cluster concentration is marked by widespread exposures of Miocene, Eocene, aH Cretaceous 

rocks, whereas the respective productive basins 

are covered by Pliocene and Pleistocene rocks.

The widespread occurrences of Eocene and Cretaceous exposures and the absence of upper 

Miocene and Pliocene units preclude the possible 

presence of the most prolific petroleum-bearing 

sections in the cluster area. For example, approximately 99 percent of the total recoverable hydrocarbons in the Ventura Basin is in the postEocene section. About 65 percent c^ the total hydrocarbons has been found in the PPocene section, 

which attains a thickness of about 15,000 ft (4,600 

m) in the central part of the Ventura Basin. In the 

Santa Maria Basin to the west of cMster 3, all of 

the hydrocarbons found to date are of post-Eocene 

age, generally middle Miocene and younger.

Cluster 4 is contained within the most northerly 

and least prolific province in this group (fig. 3). 

Four fields have been found in the Cuyama Valley 

for a total of 286 million barrels of oil and 235 billion cubic feet of gas. The South Cuyama field accounts for 75 percent of the oil and 82 percent of 

the gas. The oil and gas in all four fields is in the 

Vaqueros sandstone of lower Miocene age, and 

this unit is missing over much of cluster 4 because 

of outcropping of older units.

In summary, the geology withh the cluster 

group is fairly consistent, and the major producing 

sections of the three provinces (Pliocene in Ventura Basin, middle Miocene in Sants Maria Basin, 

and lower Miocene in Central Coastal Basin) are 

missing in the cluster area, and any major production would probably be from older stratigraphic

D10
units. The cluster is given a low potential rating 

for these reasons.

Cluster 5 Province 78 Central Coastal Basins

This cluster is within the Caliente Range in the 

south-central part of the Central Coastal Basins 

province (fig. 3). The tract is just north of the 

Cuyama Valley and within 2 miles (3.2 km) of the 

Russell Ranch field that has an estimated ultimate 

recovery of 68 million barrels of oil and 50 billion 

cubic feet of gas from the lower Miocene Vaqueros 

Sandstone. Surface beds in the tract area are of 

Miocene age and the lower Miocene Vaqueros 

should be present at depth. This accounts for the 

medium potential rating given to the cluster.

Cluster 6 Province 78 Central Coastal Basins

This cluster is located in the south-central part 

of the Central Coastal Basins province (fig. 3) 

along the southwest side of the Salinas Valley. 

Five fields have been discovered along a northwest-southeast trend in the center of the Salinas 

Valley. Ultimate recoverable oil is estimated at 

360 million barrels with more than 99 percent of 

this credited to the San Ardo field. Production is 

from the middle Miocene Monterey and gravity is 

low, 10 to 13 degrees, API gravity.

More than 30 wildcat tests have been drilled 

within 5 miles of the wilderness cluster along the 

north and east side, without success. Nearest production is at the Monroe Swell field about 10 miles 

to the east of the cluster. This field has estimated 

reserves of 2 million barrels.

The low potential rating given this wilderness 

cluster is due partly to the generally poor quality 

of fields found to date (San Ardo excepted) and 

partly to the lack of success in the concentrated 

exploration activities near the cluster.

Cluster 7 Province 81A Eastern California

Cluster 7 is in the Cascade-Modoc subprovince 

of northeastern California (fig. 3). The area is 

given a low to zero potential rating on the basis of 

the unfavorable geological conditions of widespread Cenozoic volcanic rocks over most of the 

area and the lack of significant amounts of marine 

strata that could be source rocks. In addition, 

none of the wells drilled to date has reported any 

shows of oU or gas.

The low to zero potential rating is consistent 

with the evaluation of "little petroleum potential"

given in AAPG Memoir 15 (Gay and 

1971).

Clusters 8 and 9 Province 81A Eastern California

Cluster 8 is in the Great Basin subprovince and 

cluster 9 is in the Mojave subprovince of the Eastern California province (fig. 3). The combined subprovinces form a large area that offers very limited possibilities for oil and gas. Because the rocks 

were subjected to intense tectonism with resulting 

metamorphism and structural complexities, there 

is little chance for the presence of source rock, reservoir rock, and suitable trapping mechanif^s. A 

low to zero potential rating is given the tw> clusters.

Cluster 10 Province 81A Eastern California

Cluster 10 is in the Imperial Valley subprovince 

located near the southeastern corner of California 

(fig. 3). Approximately 40 exploratory well'' have 

been drilled in this subprovince in search of oil 

and gas and only minor shows of gas have been reported.

The failure to find oil or gas in the wells drilled 

to date and the apparent lack of suitable source 

beds justify a low to zero potential rating f>r this 

cluster.

Cluster 11 Province 81A Eastern California

Cluster 11 is a single wilderness tract in the 

southwest corner of the State (fig. 3). It is heated 

near the eastern limit of the San Diego area of the 

narrow coastal strip of the Peninsular Rang'e subprovince of the Eastern California province, 81A.

The up-dip location of the tract places it in a 

position where the sedimentary section is quite 

thin. Three tests were drilled in 1910 and 1931 

with locations about 5 miles west of the tract in a 

down-dip position. The depths ranged from 1,000 

to 3,000 ft (305-914 m) and the results were negative. A low to zero potential rating is given on the 

basis of a thin sedimentary section and the results 

of exploratory drilling.

Cluster 12 Province 901 Santa Lucia RangeThis cluster is located in the western half of the 

Santa Lucia Range province (fig. 3) where there 

are a few exposures of Upper CretacecTis to 

Miocene sedimentary rocks. These units are quite 

thin and a low to zero potential rating is given.

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Cluster 13 Province 902 Northern Coast Ranges

This cluster is in the northern part of the province (fig. 3) where petroleum possibilities are 

considered to be very low. The bulk of the area is 

underlain by post-Nevadan (Late Jurassic to 

Early Cretaceous) granites and metamorphic 

rocks and post-Nevadan rocks that include gently 

folded to flatlying marine Cretaceous and nonmarine Tertiary sedimentary rocks. A low to zero 

potential rating is given this cluster. 

Clusters 14 and 15 Province 902 Northern Coast Ranges

Cluster 14 is in the central part of the province, 

and duster 15 is near the coast immediately south 

of Province 80, the Humboldt Basin (fig. 3). The 

dominant rocks in this area belong to the Franciscan Complex of Late Jurassic to Tertiary age. 

This series is composed of graywackes, cherts, 

limestones, shales, and volcanic rocks that are 

metamorphosed to various degrees.

Oil seepages and a subcommercial oil accumulation have been found in the youngest and least altered part of the section. Additional small accumulations may be found. These clusters are ranked as 

having low to zero potential.

Cluster 16 Province 902 Northern Coast Ranges

This cluster lies along the Pacific Coast in the 

vicinity of Drakes Bay, a few miles northwest of 

San Francisco (fig. 3). This area lies to the west 

of the San Andreas fault, and Tertiary beds are 

exposed along this coastal strip. Several wells 

have been drilled in the general area, both onshore and offshore, without success. A low to zero 

potential rating is given this cluster.

SUMMARY

Of the total 18.9 million acres of Wilderness 

Lands in California the petroleum potential by acreage can be summarized as follows: medium to 

low potential, 1.347 million acres; low to zero potential, 10.249 million acres; and zero potential, 

7.253 million acres. The petroleum potential by 

acreage of all Wilderness Land categories in the 

Western United States is shown in this circular by 

B. M. Miller in table 1, chapter P.

SELECTED REFERENCES

Alpha, A. G., 1971, Petroleum potential of Sierra Nevada and 

eastern Desert, California: American Association of Petroleum Geologists, Memoir 15, v. 1, p. 363-371.

Baldwin, T. A., 1971, Petroleum potential of California central 

Coast: American Association of P *roleum Geologists, 

Memoir 15, v. 1, p. 309-315.

Bureau of Land Management, 1981, WiMerness Status Map, 

State of California, U.S. Department of Interior, 

1:1,000,000 (1 sheet).

California Division of Oil and Gas, 1981,6"th Annual Report of 

the State Oil and Gas Supervisor, California Department 

of Conservation, Division of Oil and Gas Publication PR06.

California oil and gas fields, volumes I and II, 1973: California Division of Oil and Gas.

Galloway, D. C., 1971, Petroleum potential of San Joaquin 

Basin, California: American Association of Petroleum 

Geologists, Memoir 15, v. 1, p. 239-253.

Crawford, F. D., 1971, Petroleum potential of Santa Maria 

province, California: American Association of Petroleum 

Geologists, Memoir 15, v. 1, p. 316-3^.

Dolton, G. L., Carlson, K. H., Charpentfer, R. R., Coury, A. 

B., Crovelli, R. A., Frezon, S. E., K' an, A. S., Lister, J. 

H., McMullin, R. H., Pike, R. S., lowers, R. B., Scott, 

E. W., and Varnes, K. L., 1981, F^imates of undiscovered recoverable conventional resources of oil and gas in 

the United States: U.S. Geological Sirrvey Circular 860, 87 

PGay,T. E., Jr., and Streitz, R., 1971, Petroleum potential of 

Modoc Plateau and Cascade Range, northeastern California: American Association of Petroleum Geologists, 

Memoir 15, v. 1, p. 360-362.

Gray,C.H., Jr., Kennedy,M.P., and Moiton, P. K., 1971, Petroleum potential of southern coastal and mountain area, 

California: American Association of Petroleum Geologists, 

Memoir 15, v. 1, p. 372-383.

Hobson, H. D., 1971, Petroleum potential of northern Coast 

Ranges, California: American Association of Petroleum 

Geologists, Memoir 15, v. 1, p. 339-35"

Jennings, C. W., Boylan, R. T., Moar,R. R.,and Switzer, R. 

A., 1977, Geological map of California- Resources Agency, 

Department of Conservation, State of California.

Killkenny, J. E., 1971, Future petroleum potential of Region 

2, Pacific coastal states and adjacent continental shelf and 

slope: American Association of Petroleum Geologists, 

Memoir 15, v. 1, p. 170-177.

Landes, K K., 1970, Petroleum geology o*the United States: 

Wiley-Interscience, N.Y., p. 457-489.

Munger Map Book, California-Alaska oil and gas fields, 1980.

Nagle, H. E., and Parker, E. S., 1971, Frfture oil and gas potential of onshore Ventura Basin, California: American Association of Petroleum Geologists, Memoir 15, v. 1, p. 254- 

297.

Nehring, R., 1981, The discovery of significant oil and gas 

fields in the United States: The Rand Corporation, Santa 

Monica, California, p. 38-41, 98-100.

Oakeshott, G., 1978, California's changing landscapes a guide 

to the geology of the state, McGraw F'll Publishing Company.

Tarbet, L. A., 1971, Petroleum potential of Imperial Valley, 

California: American Association of Petroleum Geologists, 

Memoir 15, v. 1, p. 384-391.

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