U.S. Department of the Interior

U.S. Geological Survey

Mid-Tertiary Isopach and Lithofacies Maps for the

Los Angeles Region, California: Templates for

Palinspastic Reconstruction to 17.4 Ma

Professional Paper 1690

PACIFIC

OCEAN

?

500

1000

1500

2000

2500

? ?

?

?

? ?

500

1000

1500

1500

1500

2000

2000

2000

2500

1200

3000

3500

4000

1500

?

?

?

?

? ?

? ? ? ? ? ?

? ? ?

? ?

?

?

?

?

? ? ?

F

F

10000

? ? ? ?

?

? ? ?

?

? ? ?

? ?

4000

9000

8000

7000

6000

5000

3000 2000

4000

8000

7000

6000

5000

8000

7000

6000 5000

3000
Mid-Tertiary Isopach and Lithofacies Maps for 

the Los Angeles Region, California: Templates 

for Palinspastic Reconstruction to 17.4 Ma

By Thane H. McCulloh and Larry A. Beyer

A preliminary palinspastic reconstruction is presented of the region of the Los Angeles Basin at its 17.4 Ma inception. To create 

this reconstruction, pertinent paleomagnetic declination data are combined with new maps of the areal extent, thickness variations, and depositional facies of the >17.4 Ma Sespe-Vaqueros Formations and their equivalents.

Professional Paper 1690

 

U.S. Department of the Interior

U.S. Geological Survey 
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Any use of trade, product, or firm names in this publication

is for descriptive purposes only and does not imply endorsement 

by the U.S. Government.

United States Government Printing Office: 2004

For additional copies please contact:

USGS Information Services

Box 25286

Denver, CO 80225

This report and any updates to it are available at

http://geopubs.wr.usgs.gov/prof-paper/pp1690/

Additional USGS publications can be found at

http://geology.usgs.gov/products.html 

For more information about the USGS and its products:

Telephone: 1–888–ASK–USGS (1-888-275-8747)

World Wide Web: http://www.usgs.gov/

Text edited by Peter H. Stauffer 

Layout and design by Stephen L. Scott 

Manuscript approved for publication, October 30, 2003

FRONT COVER

Mapped d�

margins of depositional basins of Sespe-Vaqueros Formations draped on a shaded relief map of the study area. Data are adapted from figures 3 

and 4, pages 5 and 6�

Dataset (NED). Topography has vertical exaggeration of x2 and sun illumination from azimuth 315° and elevation 45°. For more information on 

the NED, see http://gisdata.usgs.gov/ned/.

Cataloging-in-Publication data is on file with the Library of Congress
CONTENTS

Abstract--------------------------------------------------------------------------------------------- 1

Introduction---------------------------------------------------------------------------------------- 1

Late Eocene to late early Miocene strata—southeast sector--------------------------------- 4

Late Eocene to late early Miocene strata—northwest sector-------------------------------- 4

 South of the Malibu Coast Fault------------------------------------------------------------- 7

 Limit of marine facies and upper boundary of lower Miocene strata eastward 

 in the Santa Monica Mountains----------------------------------------------------------- 8

 Northern part of the northwest sector------------------------------------------------------- 8

 Clast provenance and transport directions of Sespe Formation conglomerates------- 8

 Clast provenance and transport directions in Trancas and Lower Topanga

 Canyon Formations------------------------------------------------------------------------- 8

 Summary---------------------------------------------------------------------------------------- 9

Ages of latest Oligocene and early Miocene marine strata—southeast and 

 northwest sectors---------------------------------------------------------------------------- 9

Paleomagnetic declinations and transrotation—northwest sector--------------------------- 10

Preliminary palinspastic reconstruction-------------------------------------------------------- 10

 Introduction and constraints------------------------------------------------------------------ 10

 Back-slip of fault separations---------------------------------------------------------------- 12

 Restoration of rotation------------------------------------------------------------------------ 16

 Discussion-------------------------------------------------------------------------------------- 16

Uncertainties and future challenges------------------------------------------------------------- 17

 Limits of paleomagnetic declination data--------------------------------------------------- 17

 Early extensional tectonism along the Malibu Coast-Santa Monica Fault Zone------ 17

 Central trough of the Los Angeles Basin--------------------------------------------------- 18

 Junction of the Inglewood and Santa Monica Fault Zones------------------------------- 18

Conclusion------------------------------------------------------------------------------------------ 18

Acknowledgments--------------------------------------------------------------------------------- 19

References------------------------------------------------------------------------------------------ 19

Appendix 1. Petroleum exploration drill holes that provide control on the total 

 thickness of Vaqueros and Sespe Formations (differentiated and undifferentiated) 

 or equivalents----------------------------------------------------------------------------------- 26

Appendix 2. Petroleum exploration drill holes deep enough to indicate the presence 

 of Vaqueros and/or Sespe Formations (differentiated and undifferentiated) but 

 failing to provide thickness control---------------------------------------------------------- 30

Appendix 3. Petroleum exploration drill holes that provide critical insights about the 

 regional extent and history of Vaqueros and/or Sespe strata without encountering 

 either formation-------------------------------------------------------------------------------- 32

III

FIGURES

 1. Map of the greater Los Angeles Basin showing major structural elements, faults, and geographic features-------------- 2

 2. Chronostratigraphic diagram of time and facies relationships and formation nomenclature for Post-Cretaceous 

 and pre-Pliocene rock units in the principal parts of the Los Angeles Basin region------------------------------------------ 3

 3. Map showing outcrops and present (plus restored) surface and subsurface thickness and major facies of the 

 Sespe plus Vaqueros Formations in the southeast sector------------------------------------------------------------------------- 5

 4. Map showing outcrops and present (plus restored) surface and subsurface thickness and major facies of the 

 Sespe plus Vaqueros and Trancas Formations in the northwest sector--------------------------------------------------------- 6

 5. Map of paleomagnetic declinations for the northwest sector, with major faults and selected geographic features------ 12

 6. Diagram of major fault separation estimates, noteworthy regionally developed unconformities (or depositional

 interruptions), and important igneous episodes of the greater Los Angeles region------------------------------------------- 13

 7. Preliminary palinspastic reconstruction of the greater Los Angeles Basin region-------------------------------------------- 14
IV

TABLES

 1. Age, paleomagnetic declinations, basis, and published sources for well documented localities in the 

 northwest sector of the greater Los Angeles Basin region------------------------------------------------------------------------ 11

1

Abstract

Opening of the Neogene Los Angeles Basin began 

abruptly about 17.4 Ma. Extensional rifting, with local basaltic 

volcanism, began the process and accompanied its early stages. 

Crustal detachment, followed by clockwise tectonic rotation 

and translation of large crustal blocks has been shown by previous paleomagnetic declination measurements in the western 

Transverse Ranges Province northwest of the basin and by 

large strike-slip and dip-slip separations on several major faults 

transecting it. Successful palinspastic reconstruction of the 

region to its arrangement before 17.4 Ma depends on understanding and integration of many stratigraphic and structural 

components.

Before 17.4 Ma, fluviatile, alluvial and floodplain deposits, interstratified in the younger part with shallow marine to 

deeper shelf transgressive equivalents, accumulated to thicknesses as great as several kilometers. This report maps the 

surface and subsurface extents, thickness variations, and facies 

patterns of these strata, the Sespe plus Vaqueros and Trancas 

Formations or equivalents. Separate southeast and northwest 

sectors are revealed, each with distinctive internal thickness 

and facies patterns, which must have been related before rifting and transrotation. Terrestrial vertebrate and marine molluscan and foraminiferal fossils, plus magnetostratigraphic 

profiles of other workers and a few dates of igneous rocks, 

provide timing for key depositional and structural events.

Our preliminary reconstruction of the region brings the 

internal patterns of the northwest and southeast sectors toward 

congruity but leaves unsatisfied discrepancies that suggest 

important information is missing. The reconstruction focuses 

attention on critical elements, specific uncertainties, and deficiencies of prior reconstructions. It also provides a new foundation for further work.

Introduction

Conceptual understanding of the origin and evolution 

of the Los Angeles Basin and its surroundings—shown 

with selected geographic features, faults, and structural elements in figure 1—began a notable shift following publication of the first paleomagnetic evidence implying regional 

detachment, translation, and large (“about 70 ̊”) clockwise 

steep-axis rotation of the western Santa Monica Mountains 

since early Miocene time (Kamerling and Luyendyk, 1979). 

Subsequent studies enlarged the paleomagnetic data base 

geographically and stratigraphically, made clear that the 

entire western Transverse Ranges Province (and some contiguous areas including the Channel Islands; see Kamerling 

and Luyendyk, 1985) have rotated more or less together as a 

block (Liddicoat, 1990), established that some younger formations record smaller rotations than some older formations 

(Hornafius and others, 1986), and suggest that declination 

has changed linearly since about 17 Ma at a rate of about 

“5.79 degrees/m.y.”(Luyendyk, 1990, fig. 3a). Based on 

the declination data and various assumptions or estimates 

about strike-slip separations on major to minor zones, at least 

seven substantially different regional palinspastic reconstructions have been proposed (Hornafius and others, 1986, fig. 

9; Wright, 1991, fig. 36; Crouch and Suppe, 1993; Howard 

and Lowry, 1995; Dickinson, 1996; Bohannon and Geist, 

1998; Fritsche, 1998; Ingersoll and Rumelhart, 1999). These 

models lead to differing paleogeographic reconstructions for 

the time preceding the onset of transrotation. To gauge the 

validity of those reconstructions and to improve on them if 

possible, this report presents quantitative maps of the extent, 

thickness variations, gross lithofacies distributions, and 

evidences of age for the nonmarine Eocene-lower Miocene 

Sespe Formation and the interfingering Oligocene-lower 

Miocene transgressive marine Vaqueros Formation (and its 

equivalents) in the Los Angeles Basin region. These presumed prerift and prerotational formations provide the foundation for a new preliminary reconstruction.

Nonmarine clastic strata of late Eocene to late early 

Miocene age interbedded with partly marine Oligocene to 

late early Miocene clastic strata are critical to this study and 

occur in two separate sectors. A southeast sector spans the 

San Joaquin Hills, northwestern Santa Ana Mountains, eastern portion of the Los Angeles Basin, two areas north of the 

Whittier fault, and a small area northeast of the Chino and 

Elsinore Fault Zones (fig. 1). A northwest sector covers the 

central and western Santa Monica Mountains plus buried and 

outcropping areas farther north, including the Simi Valley 

Mid-Tertiary Isopach and Lithofacies Maps for the 

Los Angeles Region, California: Templates for 

Palinspastic Reconstruction to 17.4 Ma

By Thane H. McCulloh1 and Larry A. Beyer2

1

7136 Aberdeen Avenue, Dallas, Texas 75230

2

U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 

 94025 

 Introduction
2 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

and Oakridge uplift to as far as the Oakridge-Santa Susana 

Fault Zone (fig. 1). Between the two sectors, strata of late 

Eocene to late early Miocene age are either known to be 

absent or are buried so deeply that their presence is not demonstrated.

 In both sectors, widespread thick nonmarine sandstone, 

conglomerate, and sandy claystone, with local fanglomerate 

and fluvial channel fill, are called Sespe Formation. The 

oldest floodplain and fluvial deposits are late Uintan (middle 

Eocene), on the basis of land mammal fossils from both sectors (Stock, 1948; Kelly, 1990; Calvano and others, 2003; 

Whistler and Lander, 2003). The youngest nonmarine strata 

in the sequence are Oligocene to latest early Miocene. These 

nonmarine strata are interbedded with or overlain by better 

sorted and generally finer grained greenish-gray to very dark 

gray marine sandstones and siltstones of the Vaqueros Formation in parts of both sectors. Such marine strata are abundantly fossiliferous locally, yielding mollusks and, in a few 

places, foraminifers that are indicative of early Miocene ages 

(24 to 17.5 Ma) (Loel and Corey, 1932; Yerkes and Campbell, 1979, p. E11; Schoellhamer and others, 1981; Blake, 

1983). Nonmarine interbeds and correlative facies, as well 

as some littoral Vaqueros Formation beds, have yielded land 

mammal fossils locally that are interpreted to range from 

early Arikareean (28 Ma) to latest early Hemingfordian (17.5 

Ma) in land mammal ages (Lander, 1983; Lucas and others, 

1997; Whistler and Lander, 2003). In most of the western 

Santa Ana Mountains the marine Vaqueros Formation facies 

and nonmarine Sespe Formation facies are interbedded intimately and have been mapped as “Sespe-Vaqueros undifferentiated” (Woodford and Gander, 1980, fig. 3; Schoellhamer 

and others, 1981, p. D31).

Internal depositional gaps and unconformities, some of 

long duration, are recognized within the Sespe and Vaqueros 

Formations. One spans approximately the period 40-30 Ma 

and probably is of major regional extent (Minch and others, 

1989, fig. 4; Lander, 1994, fig. 2; Prothero and others, 1996, 

figs. 8 and 9). Another is important in the southeastern 

sector (Belyea and Minch, 1989, fig. 3; McCulloh and others, 

2000, p. 1168; Calvano and others, 2003). Some are minor 

Figure 1.—The greater Los Angeles Basin region, showing major structural elements, faults (dashed or queried where uncertain), geographic 

features, and frames of subordinate southeast and northwest sectors (figs. 3, 4). Fault abbreviations: A—Anacapa, BC—Benedict Canyon, 

C—Chino, E—Elsinore, H—Hollywood, LC—Las Cienegas, MC—Malibu Coast, NIZ—Newport-Inglewood zone, O—Oakridge, PV—Palos Verdes, 

R—Raymond, S—Simi, SG—San Gabriel, SGNB—San Gabriel north branch, SM—Santa Monica, SS—Santa Susana, VC—Vasquez Creek, 

V—Verdugo, W—Whittier. Geographic abbreviations: CP—Cahuenga Pass, PH—Pacoima Hills. Oil fields: 1—Las Cienegas, 2—Inglewood, 

3—Sawtelle, 4—Cheviot Hills.

central

trough

O C E A N

1

2

3

4

34°00'

33°45'

33°30'

34°15' N

119° W 118° 30' 118° 117° 30'

?

???

?

OAKRIDGE UPLIFT

SIMI HILLS

SANTA MONICA MTNS.

SANTA ANA MTNS.

10 0 10 20

Miles

10 0 10 20 30

Kilometers

NORTHWEST

SECTOR (figure 4)

SOUTHEAST

SECTOR (figure 3)

O

SS

SG

VC

SGNB

R

W

C

E

LC

PV

A

S

BC

SM

CP H

PH

SAN

JOAQUIN

HILLS

SIMI VALLEY

Los Angeles

NIZ

SAN

FERNANDO

VALLEY V

MC

N

Laguna Beach

Pomona

P A C I F I C 

figure 1

WESTERN TRANSVERSE RANGES PROVINCE

PENINSULA

 RANGES

 PROVINCE

LOS

ANGELES

BASIN

PACIFIC

OCEAN

LOCATION MAP

34°

N

120° W 119° 118° 117°
3

EOCENE

PAL.

EARLY

LATE

C23C24

C25C26

C22C21C20C19C18C17C16 LA

TE

MAG.POL.STRAT.

253035

C8C9

C10

LATE

OLIGOCENE

EARLC Y11

C12

C15

C13

10

C5

MIOCENE

MIDDLE

EARLY

TIME(Ma)

CHRONS

1520

C6

MIDDLE

5560455040

L

EPOCH

N.AMERICAN

LANDMAMMAL

AGES

CALIFORNIA

MOLLUSCAN

STAGES

CLARENDONIAN

BARSTOVIAN

HEMINGFORDIAN

ARIKAREEAN

WHITNEYAN

ORELLAN

CHADRONIAN

DUCHESNEAN

UINTAN

BRIDGERIAN

WASATCHIAN

CLARKFORDIAN

TIFFANIAN

"MARGARITAN'

"TEMBLOR"

"VAQUEROS"

UNNAMED

of Addicott, 1973

"TEJON"

"TRANSITION"

"DOMENGINE"

"CAPAY"

"MEGANOS"

"MARTINEZ"

C7

OAKRIDGESIMI

WESTERN

SANTA

MONICA

MTNS.

MALIBU

COAST

(S OF FAULT)

CENTRAL

SANTA

MONICA

MTNS.

EASTERN

SANTA

MONICA

MTNS.

LOS

ANGELES

BASIN

SYNCLINE

PUENT

HILLS

BLOCK

Conejo

Volcanics

"L.Topanga"

"Vaqueros"

Sespe

Llajas Llajas Llajas

Santa Susana Coal Canyon

Monterey Conejo

Volcanics Zuma Volc.

Trancas

Modelo

Topanga

Santiago

Silverado

Mtn.

Meadow

Dacite

Puente or

Modelo

volcanics

Topanga C.

Vaq.

Topanga with

volcanics 

Simi Cong. Simi Cong.

"Vaqueros"

Topanga w

volcanic

BASIN

OPENING

WITH

MAJOR

RIFTING

STARTING

AFTER

17.4 Ma

NORTHWEST SECTOR S

?

? ?

?

?

? 

? ?

?

? ?

?

? 

?

?

?

?

?

?

Sespe

Sespe

Sespe

Puente

?

?

Conejo

Volcanics

?

?

Santa Susana

Coal Cyn.

SOB

?

? ?

? ?

Figure 2.—Chronostratigraphic diagram of time and facies relationships and formation nomenclature for post-Cretaceous and pre-Pliocene rock units Basin region, including the southeast and northwest sectors outlined in figure 1. In magnetic polarity column, normal polarity is shown in black, reversstriping indicates absence of section; wavy lines mark unconformities or edges of time gaps. SOB = San Onofre Breccia.

Introduction
4 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

(Oborne, 1993, fig. 3) or only intimated; many others probably are unrecognized.

Submarine olivine basalt flows rest disconformably 

on Paleogene strata and unconformably on older rocks in 

the easternmost Santa Monica Mountains. These oldest of 

a regionally developed suite of Miocene basic volcanics, 

dated at 17.4 Ma (McCulloh and others, 2002), offer clues 

to tectonomagmatic events associated with onset of opening of the Los Angeles Basin and the connected clockwise 

transrotation of the western Transverse Ranges region. 

They are presumably the earliest expression of deep crustal 

magmatism accompanying extensional tectonism and mark 

the close of a long period of relative crustal stability.

These and other chronostratigraphic specifics and depositional facies variations and gaps are summarized graphically in figure 2. The formational units shown were chosen 

to emphasize depositional and other events closely preceding 

17.4 Ma; scant attention is given to all other events.

Late Eocene to Late Early Miocene 

Strata—Southeast Sector

Outcrops of coarse fluviatile conglomerate and interbedded nonmarine arkosic sandstone and mudstone of the Sespe 

Formation, plus less abundant finer grained silty sandstone 

of the Vaqueros Formation facies, are exposed principally in 

the northwestern Santa Ana Mountains and San Joaquin Hills 

(Vedder and others, 1957; Woodford and Gander, 1980, fig. 

3; Schoellhamer and others, 1981; Belyea and Minch, 1989). 

Limited outcrops of partly correlative nonmarine strata also 

occur northeast of the Whittier Fault Zone (Durham and 

Yerkes, 1964), and mostly nonmarine beds crop out northeast of the Chino and Elsinore Fault Zones (Gray, 1961; 

Schoellhamer and others, 1981). Subsurface Sespe and 

Vaqueros Formation strata have been sampled from a few 

dozen deep petroleum exploration drill holes to the north 

and west of the outcrop areas. The distribution of Sespe and 

Vaqueros Formation strata is thereby extended over a much 

larger area than is suggested by the outcrops (Schoellhamer 

and others, 1981, p. D72-D81; West and Redin, 1991a, 

1991b; McCulloh and others, 2001, fig. 5). 

Stratal thicknesses of Sespe plus Vaqueros Formations 

taken from drill holes (appendix 1) have been combined 

with those measured at outcrops to provide a new map of the 

distribution and thickness variations of the combined formations (fig. 3).

Edges of the mapped strata result from a combination 

of postdepositional erosion, depositional limits or basin 

margins (locally), and lack of subsurface control. Original depositional limits are suggested where the extent of 

postdepositional erosion can be confidently inferred. Limits 

caused by erosion are also shown where they are recognized.

Strata north of latitude 33.85 ̊ N and nearly all strata east 

of longitude 117.6 ̊ W are nonmarine fluviatile sandstones 

and gravels. Strata south of latitude 33.85 ̊ N are mostly 

nonmarine also, but with fossiliferous marine interbeds, 

especially at and near the top of the sequence. To the 

southwest, in the San Joaquin Hills, a younger Vaqueros 

Formation is readily distinguishable at mapping scales from 

an underlying distinctive nonmarine and generally coarser 

Sespe Formation (Vedder and others, 1957; Woodford and 

Gander, 1980, fig. 3).

The maximum areal limits of the transgressive marine 

Vaqueros Formation facies is a proxy for an early Miocene 

proximal shoreline of the Sespe-Vaqueros Formations of the 

southeastern section. Our focused fieldwork, together with 

published data (Vedder and others, 1957; Gray, 1961; Yeats, 

1976; Woodford and Gander, 1980, fig. 3; Schoellhamer and 

others, 1981; Daniel-Lyle, 1995, fig. 6; Howard and Lowry, 

1995, fig. 2) define the shoreline in the outcrop areas. Available drill hole samples and records have been analyzed to 

extend the marine facies and its northern limit westward 

from the northern Santa Ana Mountains outcrops to the western edge of subsurface control. The resulting newly mapped 

area of marine facies clearly defines an early Miocene southwestward-opening transgressive marine embayment separated from more northerly and easterly areas of exclusively 

fluviatile and alluvial deposits, the “Santa Ana Bay” of Loel 

and Corey (1932) (fig. 3).

The provenance of certain distinctive, locally derived 

Sespe Formation clasts from both outcrops and drill-hole 

samples of strata younger than 27 Ma in the northern part 

of the southeast sector (McCulloh and others, 2001, fig. 6) 

indicate transport of clasts to the southeast, south, and southwest. Other clasts of nondiagnostic lithologies might also be 

locally derived, and many others might have been recycled 

from older local sedimentary units. However, many more 

distinctive exotic imports carry important paleogeographic 

implications (Woodford and others, 1968, 1972; Woodford 

and Gander, 1980; Lane, 1989; Howard, 2000). Evidently 

most of these imports were transported into the basin from 

the east or northeast, judging from clast size gradations and 

paleocurrent indicators (Belyea and Minch, 1989, fig. 5, table 

4; Howard and Lowry, 1995, fig. 2). 

The isopach contours (fig. 3) define an apparent axis of 

greatest thickness that trends northeast to northwest and that 

is nearly orthogonal to the line showing the most northerly 

extent of marine facies. The Sespe-Vaqueros trend of greatest thickness crudely mimics the underlying north-southtrending Paleocene-early Eocene axis of greatest thickness 

(McCulloh and others, 2000, fig. 4). Possible implications 

of the north-trending Sespe-Vaqueros maximum thickness 

trough and the stratal thinning near the west end of the 

marine-nonmarine facies line are discussed later.

Late Eocene to Late Early Miocene 

Strata—Northwest Sector

Great stratal thicknesses, complex facies relationships, 

poor exposures in many places, and vexing local structural 
5

Figure 3.—Outcrops and present (plus restored) surface and subsurface thickness and major facies of the Sespe plus Vaqueros Formations 

in the southeast sector. “Reconstructed basin margin” is an estimate of the original extent of Sespe-Vaqueros strata for the depositional 

system.

Late Eocene to Late Early Miocene Strata—Southeast Sector

Outcrops

SESPE-VAQUEROS Formations

undifferentiated

Subsurface partly marine

Subsurface nonmarine only

EXPLANATION

Line of equal thickness in feet (dashed

 and dotted where less certain)

CONTACT RELATIONS Important faults (long dash where 

 uncertain, short dash where inferred, 

 and queried where doubtful).

Outcrops of Peninsular 

 Ranges Province basement

Erosional edge

Reconstructed basin margin

Edge of marine facies PRE-CRETACEOUS rocks

?

118°W 117°30'

33°30'

34°N

500

1000

1500

2000

2500

Kilometers

5 0 5 10 15

P A C I F I C O C E A N

? ?

?

?

?

? ?

500

1000

1500

1500

1500 2000

2000

2000

2500

1200

3000

3500

4000

1500

?

? ?

CHINO FAULT

W H I T T I E R F A U L T Z O N E

ELSINORE F.

SANTA ANA MTNS.

E D

G

E

O

F

S

U

B

S

U

R

F A C E

C O N

T

R O

L

?

?

?

? ?

?

?

?

?

42

2

3

4

5

6

7

8

9

10

11 12

13

14

15

16

17

18

19

20

21

22

23

50

51

38

47

57

48 33

56

46

45

40

41

43

49

34

36

54

53

55 44

1

35

39

52

2000

N

37

56

16

?

?

?

?

?

?

? ? ?

F

F

Prospect well that penetrates

 base of Sespe-Vaqueros Fm or

 equivalent (see appendix 1)

Prospect well that bottoms 

 within Sespe-Vaqueros Fm or

 equivalent (see appendix 2)

F Key Vaqueros marine fossil localities

DATA POINTS

?

?

?
6 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

complications of the late Eocene-early Miocene sequence 

of the central and western Santa Monica Mountains all 

combine, with some weaknesses in fossil control and innumerable middle Miocene intrusions, to defy simple summary. Our description attempts to make comprehensible 

a very large and complex mass of structurally disturbed 

stratified rocks. Our simple model—a single isopach map 

(fig. 4)—combines the aggregated thicknesses of the late 

Eocene-early Miocene Sespe Formation, the Oligoceneearly Miocene Vaqueros Formation, and the early Miocene 

parts of the Topanga Canyon Formation of Yerkes and 

Campbell (1979). The most important prior sources for 

this model are Arnold (1907, p. 525-526), Kew (1923), 

Woodford and Bailey (1928), Loel and Corey (1932), Soper 

(1938), Durrell (1954), Nagle and Parker (1971), Weber and 

others (1973), Stuart (1976), Vedder and Howell (1976), 

Truex (1976), Stuart (1979), Yerkes and Campbell (1979), 

Turner and Campbell (1979), Yerkes and Campbell (1980), 

OAKRIDGE FAULT

10000

SANTA SUSANA FAULT

SIMI FAULT

MALIBU COAST F

?

?

?

?

?

?

?

?

?

?

?

?

Outcrops

SESPE-VAQUEROS Formations 

undifferentiated

Subsurface partly or mainly marine

Subsurface nonmarine only

EXPLANATION

Line of equal thickness in feet (dashed

 and dotted where less certain)

CONTACT RELATIONS Important faults (long dash where 

 uncertain, short dash where inferred)

Outcrops of Santa Monica 

 Slate and intrustive 

 granodiorite

Erosional edge

Reconstructed basin margin

Edge of marine facies PRE-CRETACEOUS rocks

2000

56

16

Prospect well that penetrates

 base of Sespe-Vaqueros Fm or

 equivalent (see appendix 1)

Prospect well that bottoms 

 within Sespe-Vaqueros Fm or

 equivalent (see appendix 2)

Prospect well that provides critical insight

 (see appendix 3)

DATA POINTS

59

28

31

27

24

59

26

30

25

29

58

34° 

15’

N

34°

119° W 118° 30'

N

Kilometers

5 0 5 10

P A C I F I C O C E A N

O A K R I D G E U P L I F T

S I M I H I L L S

SIMI VALLEY

S A N T A M O N I C A M T N S.

? ?

4000

9000

8000

7000

6000

5000

3000

2000

4000

8000

7000

6000

5000

8000

7000

6000

5000

3000

Santa

Monica

Figure 4.—Outcrops and present (plus restored) surface and subsurface thickness and major facies of the Sespe plus Vaqueros and Trancas 

Formations and equivalent units in the northwest sector. “Reconstructed basin margin” is an estimate of the original extent of Sespe-Vaqueros 

strata for the depositional system.
7

Dibblee (1982), Howard (1989), Dibblee and Ehrenspeck 

(1990), Fritsche (1993), Oborne (1993), and Campbell and 

others (1996). Our model relies heavily on the published 

isopach maps of Nagle and Parker (1971, figs. 7 and 8) 

in the western part of the Santa Monica Mountains and 

the part of the northwest sector that is west and southwest 

of the Simi Hills. Sespe Formation and lower Miocene 

isopach maps of Nagle and Parker (1971) were summed and 

adjusted to agree with structure sections closely controlled 

by outcrop geology (Campbell and others, 1996; Dibblee 

and Ehrenspeck, 1990; Yerkes and Campbell, 1980) and, in 

a few places, with drill hole control. The model also reflects 

results of our selective field work plus interpretations of 

land-mammal fossils from younger parts of the Topanga 

Canyon Formation in the east-central parts of the mountains 

(Whistler and Lander, 2003).

The total aggregate thickness of the Sespe, Vaqueros, 

and the early Miocene part of the Topanga Canyon Formation is conservatively estimated to exceed 2,300 m (7,500 ft) 

in the west- central Santa Monica Mountains near longitude 

118.75 ̊ W, and it might be as much as 3,000 m (10,000 

ft). This is so despite a prominent erosional unconformity 

that separates the sequence from the overlying middle Miocene Conejo Volcanics (≤16.7 Ma; Turner and Campbell, 

1979, table 1) and another local erosional break within the 

sequence between the Vaqueros Formation and overlying 

early Miocene parts of Topanga Canyon Formation strata 

(Oborne, 1993, fig. 3). The thickness diminishes eastward 

as the nonmarine Sespe Formation (facies) coarsens and 

becomes dominant (Yerkes and Campbell, 1979, fig. 3; 

Fritsche, 1993, fig. 4). Redbeds of the Sespe Formation do 

not crop out west of about longitude 118.85 ̊ W, but they are 

present and thick in deep drill holes to and beyond the western edge of our map (Nagle and Parker, 1971, fig. 7; Dibblee 

and Ehrenspeck, 1990; Campbell and others, 1996; appendix 1). For example, many deep drill holes farther northwest near longitude 119.12 ̊ W penetrated Sespe Formation 

that alone ranges up to 1,800 m (6,000 ft) thick (Nagle and 

Parker, 1971, fig. 7). We estimate conservatively that the 

aggregate thickness of the Sespe, Vaqueros, and early Miocene parts of the Topanga Canyon Formations is greater than 

3,000 m (10,000 ft) at the western edge of our map area.

 Exposed strata older than Conejo Volcanics are dominantly muddy marine sandstone and siltstone in the western 

part of the mountains, reflecting the east-to-west transition 

from largely nonmarine to offshore marine facies during 

later early Miocene deposition. Dolomitic concretions 

and beds and thin or lenticular conglomerates are present 

but rare. Macrofossils occur sparsely, mostly within the 

sequence mapped as “Vaqueros” (Loel and Corey, 1932; 

Weber and others, 1973). The overlying Encinal Member of 

the Topanga Canyon Formation is dark mudstone, interbedded in many places with sandstone and containing dolomitic 

concretions in its lower parts. On the basis mainly of its 

microfauna, we agree with Nagle and Parker (1971, fig. 8) 

and Fritsche (1993, fig. 4) that the Encinal Member (facies) 

is all early Miocene, older than 16.4 Ma (Barron and Isaacs, 

2001, fig. 22.1), although Yerkes and Campbell (1979, p. 

E16) consider it to be chiefly middle Miocene. 

South of the Malibu Coast Fault 

The east-west-trending Malibu Coast Fault Zone 

bounds the south margin of the Santa Monica Mountains 

east of a point near longitude 118.94 ̊ W, where it crosses 

the shoreline. West of that point it continues westward 

offshore (Junger and Wagner, 1977; Pinter and others, 

1998, fig. 1; Seeber and Sorlien, 2000, fig. 1; Sorlien and 

others, 2000, fig. 1). Sespe Formation and older strata are 

unknown south of the Malibu Coast Fault Zone. The oldest 

strata seen there are mostly marine sandstones interbedded 

with minor mudstone and pebbly sandstone plus distinctive 

interbedded schist breccia, also called the San Onofre Breccia (Woodford and Bailey, 1928; Stuart, 1976, 1979). This 

breccia is composed almost entirely of unsorted angular 

blocks of green schist, glaucophane schist, metagabbroic 

rocks and related lithologies derived from the distinctive 

Jurassic Catalina Schist. The Catalina Schist is known to 

be present in place offshore and onshore to the south and 

southeast and consists of distinctive oceanic glaucophanebearing schist, greenschists, and related metagabbroic rocks 

(Schoellhamer and Woodford, 1951; Hill, 1971; Yeats, 1973, 

1974; Sorensen, 1985).

 The heterogeneous sedimentary sequence limited to 

the coastal strip south of the Malibu Coast-Santa Monica 

Fault Zone and west of Point Dume has been called Trancas 

Formation (Yerkes and Campbell, 1979, p. E25-E27). It 

bears some resemblance to parts of the Vaqueros and lower 

Topanga Canyon Formations exposed north of the offshore 

projection of the fault zone (Dibblee and Ehrenspeck, 1990) 

farther west and near Point Mugu. Marine fossils occur 

but tend to be poorly preserved and long-ranging mollusks. Turritella ocoyana Conrad has been identified and 

interpreted as “Temblor” provincial molluscan stage early 

to middle Miocene (Yerkes and Campbell, 1979, p. E27). 

These strata west of Point Dume are here considered to be 

early Miocene because they lack clasts of the <16.7 Ma 

Conejo and Zuma Volcanics and seem to predate the 17.4 

Ma oldest Topanga volcanics (Hoots, 1931) of the eastern 

Santa Monica Mountains.

The base of the Trancas Formation is not exposed. We 

and others infer that it rests directly on Catalina Schist 

without intervening thick Cretaceous, Paleocene, middle 

Eocene, or Sespe sedimentary units that are present north of 

the Malibu Coast Fault (Campbell and others, 1966, fig. 3). 

If this inference is incorrect, another complicated structural 

arrangement is needed to explain the presence within the 

Trancas Formation of coarse breccia composed predominantly of large, unworn blocks of Catalina Schist (Stuart, 

1976, fig. 6). The Anacapa Fault, which appears to mark the 

southern edge of the western Transverse Ranges Province 

(Yerkes and Lee, 1979, p. 34), may or may not have been 

a factor controlling the deposition of the schist breccia in 

Late Eocene to Late Early Miocene Strata—Northwest Sector
8 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

the Trancas Formation. Whatever the case, the age of the 

youngest Trancas Formation is important for understanding 

the structural evolution. 

Limit of Marine Facies and Upper Boundary of 

Lower Miocene Strata Eastward in the Santa 

Monica Mountains

The easternmost extent of marine strata in the combined 

Sespe-Vaqueros-Topanga Canyon Formations is a final 

important element of the Santa Monica Mountains part of 

the northwestern sector stratigraphy. Most of the marine 

sequence in the western part of the mountains, the Vaqueros 

and overlying Topanga Canyon Formations, grades eastward 

into nonmarine Sespe Formation and its partial equivalent, 

the nonmarine Fernwood Member of the Topanga Canyon 

Formation (Yerkes and Campbell, 1980). The easternmost 

outcrops of Vaqueros Formation are west of longitude 

118.56 ̊ W. Land mammal fossils from the Fernwood 

Member (nonmarine) are “early late Hemingfordian (late 

early to early middle Miocene)” (Whistler and Lander,

2003) (or 19.0-16.6 Ma), suggesting that the overlying Cold 

Creek Member (marine) is partly or entirely middle Miocene. Although the lower part of the Cold Creek Member 

might be equivalent to the uppermost parts of some of the 

undifferentiated Topanga Canyon Formation west of longitude 118.67 ̊ W, we exclude all of it where it has been separately mapped farther east. Thus the type “Topanga Canyon 

fauna” (Arnold, 1907; Kew, 1923), long assigned to the 

“Temblor Stage” of the middle early to middle Miocene and 

present in the upper part of strata mapped as the Cold Creek 

Member, is excluded from our maps and correlations. This 

exclusion does not influence the placement of the easternmost marine facies boundary. 

One final point of control is the Atlantic Oil Co. “Nettleship” No. 1 (fig. 4, prospect well No. 24; appendix 1), 

which penetrated fossiliferous “Vaqueros” and underlying 

Sespe Formation and bottomed in marine Eocene or older 

strata (core samples and U. S. Geological Survey file data). 

These drill hole data, together with outcrop fossil control, 

support both isopach lines and the location of the line 

approximating the easternmost extent of marine facies.

Northern Part of the Northwest Sector

Understanding of the distribution, thickness, and facies 

of the Sespe and Vaqueros Formations north of the Santa 

Monica Mountains is partial and uneven. Postdepositional 

uplift and erosion completely removed evidence in a large 

area south of the Simi Fault and also limits accurate appraisals in extensive outcrops north of that fault. Despite such 

limitations, approximate isopachs and an estimate of the 

reconstructed landward edge of the transgressive marine 

facies are presented here (fig. 4). These are based importantly on the work of Bailey (1947), Hall and others (1975), 

Blake (1983), Blundell (1983), Seedorf (1983), Yeats 

(1987), and Huftile (1988) and on a few deep drill holes 

(appendix 1). Combined Sespe and Vaqueros Formation 

strata in this northern part of the sector are more than 2,400 

m (8,000 ft) thick in the eastern part of a west-trending 

isopach maximum just south of the Oakridge Fault Zone 

(Bailey, 1947; Huftile, 1988, p. 125-132). An erosional 

break between Vaqueros and Sespe strata in part of the area 

(Huftile, 1988) suggests an originally even greater composite thickness along part of the Oakridge uplift.

Clast Provenance and Transport Directions of 

Sespe Formation Conglomerates

Trends of maximum clast size and abundance in Sespe 

Formation conglomerates of the Santa Monica Mountains 

and Simi Valley indicate predominantly east-to-west sediment transport, consistent with indications from clast imbrications and trough cross bedding (Howard, 1989, figs. 9, 10; 

Howard and Lowry, 1995, fig. 2, table 2). Most clasts are 

compositionally unlike present-day bedrock sources to the 

east or are nondiagnostic lithologies. Important exceptions 

include rare anorthosite clasts (unconfirmed by us) reported 

from the uppermost Sespe Formation of the Simi Hills 

(Paschall and Off, 1959, p. 6; Paschall and Off, 1961, p. 

1953; Taylor, 1984; Lander, 1994, p. 86) and from the lower 

Miocene Topanga Canyon Formation of the central Santa 

Monica Mountains (Flack, 1993, p. 67). Probable noteworthy exceptions are the tourmalinized quartz monzonites, 

quartz diorites, and quartzites reported by R. R. Simonson 

from the lower Sespe Formation conglomerates of the central Santa Monica Mountains (Soper, 1938, table 1). As 

described, some of these strongly resemble tourmalinized 

Mesozoic rocks from the northwestern Peninsular Ranges 

about 80 miles to the east (Irving, 1937, p. 300). Still other 

possible exceptions are clasts of nondurable schist, slate, 

meta-andesite, and metadiabase that resemble bedrock metamorphic rock types of the northern Santa Ana Mountains. 

Lane (1989), Howard and Lowry (1995, p. 29-32), and 

Howard (2000) discuss the latter special exceptions and suggest possible sources for such metamorphic clasts and the 

much more abundant and durable distant imports.

Clast Provenance and Transport Directions in 

Trancas and Lower Topanga Canyon 

Formations

The most noteworthy exception to the overall pattern 

of sediment transport from east to west for Sespe, Vaqueros, and Topanga Canyon Formations of the Santa Monica 

Mountains and Simi Valley occurs in the Trancas Formation along the coast west of Point Dume and south of the 

Malibu Coast Fault and in the lower Topanga Canyon Formation north of the fault east and west of Point Mugu. San 

Onofre Breccia (Woodford and Bailey, 1928), interbedded 
9

with arkosic sandstone and muddy siltstone and derived 

from unique metamorphic sources nearby to the south, 

was transported northward into the basin along short paths 

that limited clast rounding or sorting (Stuart, 1976, fig. 

6). Occurrences of breccia in the Trancas Formation are 

prominent at Lechuza Point and intermittently from there 

along the beach for almost 5 km (3 miles) to the west (Dibblee and Ehrenspeck, 1990). Glaucophane schist detritus 

occurs north of the Malibu Coast Fault in Lower Topanga 

sandstones (Dibblee and Ehrenspeck, 1990) and conglomerates about 14.5 km (9 miles) westerly from Lechuza Point 

and also about 1.5 km (1 mile) west of Point Mugu. This 

sedimentation probably overlaps the time during which 

the “Piuma,” “Saddle Peak,” and parts of the “Fernwood” 

Members of the Vaqueros-Topanga Canyon Formations 

(Yerkes and Campbell, 1979, fig. 3; Fritsche, 1993, fig. 4) 

were being deposited by westward-flowing streams on a 

floodplain northeast of the Malibu Coast Fault. Multiple 

but uncommon subrounded clasts of arkose and feldspathic 

siltstone, one boulder of foraminiferal calcareous siltstone, 

and multiple but rare subrounded clasts of fossiliferous 

oyster-bearing sandstone occur among angular blocks of 

schist at Lechuza Point. These show that at least a thin 

blanket of sedimentary strata, resembling more durable parts 

of the Encinal Member of the Topanga Canyon Formation 

and composed of detritus from granitoid sources, probably 

covered parts of the Catalina Schist source terrain prior 

to breccia deposition. The absence of associated clasts of 

Zuma Volcanics (fig. 2) shows that both the breccias and 

associated finer grained strata west of Point Dume predate 

the middle Miocene volcanism instead of being contemporaneous (Yerkes and Campbell, 1979, fig. 5, p. E28). Schistbearing prevolcanic strata from north of the Malibu Coast 

Fault to the west near Point Mugu were also at least partly 

derived from the south but are overwhelmingly dominated 

by sand-size detritus of granitoid derivation, indicating 

mixed provenance. The easternmost of these occurrences 

is in the “Lower Topanga” (Dibblee and Ehrenspeck, 1990) 

probably less than 1,400 m (4,500 feet) below the base of 

the Conejo Volcanics about 5 km (3 miles) east-southeast 

of Point Mugu. A complex paleogeography, engendered 

by a complicated prior structural rearrangement, is clearly 

indicated by these facts and invites more precise dating and 

further analysis.

Summary

Noteworthy features of the northwest sector isopachfacies map (fig. 4) are variable and locally large thicknesses, 

approximate east-west trends of the axes of greatest and 

least thickness, eastward thinning and coarsening toward 

a crudely north-south-trending edge of the marine facies, 

and evidence of localized derivation from the south in some 

of the younger units. The thickness trends, like those of 

the southeast sector, imply fundamental tectonic control of 

relative rates of subsidence. In both sectors, the 25-m.y. 

or possibly longer duration of the sedimentary record of 

that tectonic control presents an opportunity for improving 

understanding of crustal conditions preceding the abrupt 

onset of opening of the Los Angeles Basin. 

The patterns of areal extent, thickness, and empirical limits of the transgressive marine facies of Sespe and 

Vaqueros plus equivalent lower Miocene strata provide basic 

templates (figs. 3, 4) for reconstructing the paleogeology 

prior to the very different conditions that followed 17.4 Ma. 

These templates are used later in a preliminary reconstruction. Sources of clasts, directions of sediment transport, and 

the nature of the depositional environments augment thickness and facies patterns but are no substitute for them.

Ages of Latest Oligocene and Early Miocene Marine Strata—Southeast and 

Northwest Sectors

The age of our Vaqueros Formation facies, including 

partly correlative strata of the Lower Topanga (Dibblee 

and Ehrenspeck, 1990) and Trancas Formations, ranges 

from latest Oligocene (about 24 Ma) to latest early Miocene (about 17.5 Ma). This general age range is based 

upon a broad base of land mammal age ranges (Lucas and 

others, 1997; Whistler and Lander, 2003), marine mollusk 

age ranges (Yerkes and Campbell, 1979; Schoellhamer and 

others, 1981), benthic foraminiferal age ranges (Nagle and 

Parker, 1971; Yerkes and Campbell, 1979; Blake, 1983), 

magnetic polarity stratigraphy in several places (Prothero 

and others, 1996, figs. 8, 9, 11; Prothero and Donohoo, 

2001, modified following suggestions of Whistler and 

Lander, 2003; Liddicoat, 2001; Ludtke and Prothero, 2003), 

several pertinent late Oligocene radiometric dates (Mason 

and Swisher, 1989; Nourse and others, 1998; McCulloh and 

others, 2001; Lander and others, 2003), and 87Sr/86Sr fossil 

carbonate dates (17.3 Ma) for the type area of the Topanga 

Formation (McCulloh and others, 2002, table 2).

Because a numeric age for the end of deposition of the 

youngest Sespe-Vaqueros Formation strata is important for 

our reconstruction and rate estimates, available pertinent 

biochronologic data were thoroughly investigated.

Correlations and age determinations that depend exclusively on fossil mollusks should be used with caution. 

Vertipecten bowersi Arnold occurs in a number of places in 

the Vaqueros Formation of both sectors. Although the upper 

limit of its stratigraphic range in California is considered by 

many to be within the provincial Saucesian benthic foraminiferal stage (about 19.5 Ma, according to Smith, 1991, figs. 

1,12), the limiting data are weak, and it might range to the 

end of the Saucesian at about 17.5 Ma (Smith, 1991, fig. 10) 

or possibly even younger locally (Vedder, 1973). Similarly, 

the Turritella species T. ocoyana Conrad s.l. and T. inezana

Conrad s.l. are considered by some (for example, Merriam, 

1941; Campbell and Yerkes, 1979) to be guides to “Temblor” (<19.5 Ma) and “Vaqueros” (>19.5 Ma) provinicial 

molluscan stages, respectively. However, it has long been 

Age of Latest Oligocene and Early Miocene Marine Strata—Southeast and Northwest sectors
10 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

known that the two species co-occur in both sectors of our 

region (Loel and Corey, 1932, p. 264) and more widely in 

California (Vedder, 1973, fig. 9; Addicott, 1977, p. 158). 

Turritella ocoyana Conrad s.l. partly overlaps T. inezana

Conrad s.l. but may range as young as 13.6 Ma. Turritella 

inezana may be restricted to strata older than 17.5 Ma.

The Vaqueros marine transgressive event ended 

abruptly in most if not all of the Los Angeles region 

between about 17.5 and 17.4 Ma. The timing is fixed by 

the age of the unconformable base of younger Topanga 

volcanics (Hoots, 1931) of the easternmost Santa Monica 

Mountains (McCulloh and others, 2002, fig. 4), by early 

Hemingfordian terrestrial mammalian assemblages from the 

uppermost undifferentiated Sespe-Vaqueros Formation of 

the northwestern Santa Ana Mountains (Lucas and others, 

1997; Whistler and Lander, 2003, fig. 4), and by early late 

Hemingfordian land mammals from the Fernwood Member 

of the Topanga Canyon Formation (Yerkes and Campbell, 

1979, fig. 3; Fritsche, 1993, fig. 4; Whistler and Lander, 

2003, fig. 5). The timing is also compatible with 87Sr/86Sr 

ages of fossil shells from the Topanga Formation (Hoots, 

1931) type section (McCulloh and others, 2002, table 2), 

with the 15.9±0.8 Ma K-Ar age of the oldest reliably dated 

overlying Conejo Volcanics (Turner and Campbell, 1979, 

p. E21, table 1) after recalculation using current decay constants, and qualitatively with the conspicuous indications 

over much of the region of a substantial hiatus or erosional 

break separating Vaqueros Formation facies from overlying 

middle Miocene strata. 

Paleomagnetic Declinations and 

Transrotation— Northwest Sector

Paleomagnetic declination data indicate that the western Transverse Ranges Province block underwent Neogene 

clockwise transrotation of as much as 100 ̊ in some western parts beginning no later than 16 Ma (Hornafius, 1985; 

Morris and others, 1986; Luyendyk and Hornafius, 1987; 

Liddicoat, 1990; Luyendyk, 1990) and continues to rotate 

today (Molnar and Gipson, 1994). The more-or-less fixed 

rotational hub is at the east end of the block, about 25 km 

east of this study’s northwest sector. The block’s southern 

edge coincides at least roughly with the Anacapa-Malibu 

Coast-Santa Monica-Hollywood-Raymond zone of linked 

faults, possibly with some complications east of the northwest projection of the Newport-Inglewood Fault Zone. The 

block presumably became mostly detached from its deep 

crustal foundation, was accreted to the northwestwardly 

moving Pacific Plate, and then constrained to rift and rotate 

away from the North American Plate attachment, driven by 

Pacific Plate divergent motion through basal shear (Nicholson and others, 1994; Dickinson, 1996; Atwater and Stock, 

1998; Bohannon and Geist, 1998). The central and western 

parts of the northwest sector participated substantially in the 

transrotational migrations (Kamerling and Luyendyk, 1979; 

Hornafius and others, 1986; Liddicoat, 1988, 2001). It is 

unclear that the eastern extension of the northwest sector, 

east of longitude 118° 18’ W and closer to the rotational 

hub, participated equally. 

Paleomagnetic declination measurements and interpretations provide the essential quantitative and conceptual 

foundation for the transrotation of the western Transverse 

Ranges block. Published declination results from twelve 

sites are within (or closely on trend with) the northwest 

sector (table 1, fig. 5). Thoroughly documented declination 

results from stratiform rocks deposited, erupted, or intruded 

more than 10 m.y. ago are available for 10 northwest sector 

sites and one Anacapa Island site that is on trend 30 km (19 

miles) farther west. Data from a twelfth site on the southwestern tip of Point Dume are more questionable because of 

sampling limitations due to access restrictions (Liddicoat, 

1988).

The space-time patterns of paleomagnetic rotations 

in the northwest sector suggest two tendencies. First, the 

larger rotations (80 ̊ to 90 ̊) tend to occur in rock units 16 

Ma and older. Second, rocks of approximately the same 

age in different parts of the sector record different rotations, 

suggesting a mosaic of structural blocks that have moved 

semi-independently. This second tendency is supported 

by data showing that Saugus Formation fluviatile strata (< 

2.3 Ma) north of the Santa Susana Fault (outside our area) 

rotated clockwise about 30 ̊ to 34 ̊, whereas correlative units 

south of the fault (within our area) have not rotated (Levi 

and Yeats, 1993; 2001). Independently, McCulloh and others 

(2001, p. 19, 23) suggest that the northeastern continuation of the northwest sector probably records at least 20 ̊ of 

clockwise rotation since 4 to 3 Ma.

Preliminary Palinspastic 

Reconstruction

Introduction and Constraints

Palinspastic reconstruction of the parts of the Los Angeles Basin region to the time when the youngest Vaqueros 

and Sespe strata were deposited requires back-rotation of 

our northwest sector to its 17.4 Ma position—but exactly 

to where? The stratified Neogene rocks and their deforming structures hold the answers, many of which have been 

gathered during the exploration for petroleum. Evidence is 

well summarized but scattered (Woodford and others, 1954; 

Yerkes and others, 1965; Nagle and Parker, 1971; Yeats, 

1987; Wright, 1991; Blake, 1991; Rumelhart and Ingersoll, 

1997; McCulloh and others, 2000; McCulloh and others, 

2001; McCulloh and others, 2002). Although structural, 

tectonic, kinematic, chronostratigraphic, and paleodepositional-paleogeographic evidence does not constitute a sufficient basis for palinspastic reconstruction independently 

of the paleomagnetic data, it does impose time, sequence, 

and location constraints that are crucial for our preliminary 
11

reconstruction. Therefore selected diagnostic post-20 Ma 

events are summarized in figure 6.

Submarine basaltic volcanism began the Neogene 

evolutionary phase in the easternmost Santa Monica Mountains at 17.4 Ma (McCulloh and others, 2002). Volcanism 

intensified in early middle Miocene time, became more 

andesitic and partly subaerial, and spread to the western 

and northwestern and to the eastern and southeastern parts 

of the region (Shelton, 1954; Vedder and others, 1957; 

Eaton, 1958; Yerkes and Campbell, 1979; Dibblee, 1982, 

p. 102). The latest phase of volcanism apparently occurred 

in the southeast sector, concluding perhaps at 11 to 10 Ma 

(Yerkes, 1957; Yerkes, 1972; Luyendyuk and others, 1998; 

McCulloh and others, 2000; Bjorklund and others, 2002). 

Volcanism was temporally and spatially associated with 

crustal extension and widespread faulting “on northwestand north-trending faults” in the southeastern Los Angeles 

Basin (Wright and others, 1973; Wright, 1991, p. 92), and 

along northeast- to nearly east-trending faults (present coordinates) in the northwest sector (Yeats, 1983, fig. 3).

Rapid regional subsidence in the Los Angeles Basin followed volcanism and led to deposition of very thick deepsea fan and plain deposits (Redin, 1991), mainly between 

13 and 5 Ma. Dextral slip on northwest trends began during 

1 80.8-76.8 16±? four dikes 30 Kammerling and Luyendyk, 1979.

2 79.0 16±? four dikes 20 Kammerling and Luyendyk, 1979.

3 59.2 >10 &<15 one dike 22 Kammerling and Luyendyk, 1979.

4

59.2 

32.5 

70.8

10.1±2 

<10.1±2 

ca. 10?

one dike 

two dikes 

three dikes 

8 

13 

23 Kammerling and Luyendyk, 1979.

5 64.0 16.28±0.18 ten flows 49

Kammerling and Luyendyk, 1979; 

Luyendyk and others, 1998, table 1.

6 65.7 11.3-13.3

three dolomite

beds 16

Hornafius and others, 1986, fig. 3, 

table A.

7 60.7 11.3-13.3

one dolomite 

bed 4

Hornafius and others, 1986, fig. 3, 

table A.

8 35.9 11.5±1.2

two dolomite 

beds 11

Hornafius and others, 1986, fig. 3, 

table A.

9 77.5 14.6±1

Zuma Volcanics 

of Point Dume unk Berry and others, 1976.

10 94 ca. 28

Sespe Fm. at 

South Mountain unk Liddicoat, 2001.

11 64 >38

Sespe Fm. of 

Simi Valley unk Liddicoat, 2001.

12 80±9 >80

"Tuna Canyon" 

Fm; eastern end 

of central Santa 

Monica Mtns. 

(two sites) 12 Morris and others, 1986.

Map 

Symbol 

(on fig. 5)

Number of 

measurements

Source Declination 

(degrees)

Age 

(Ma) Unit(s)

Liddicoat, 1988;

Table 1.—Age, paleomagnetic declinations, basis, and published sources for well documented localities in the northwest sector 

of the greater Los Angeles basin region. 

Preliminary Palinspastic Reconstruction
12 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

Pliocene time in the Los Angeles Basin. A regime of northsouth transpression marked by reverse faulting became 

pronounced in Pliocene-Pleistocene time and is continuing 

(Hauksson and Jones, 1989; Hauksson and others, 1995; 

Wilde and Stock, 1997; Oskin and others, 2000; Bawden 

and others, 2001).

A preliminary palinspastic reconstruction of the Los 

Angeles Basin region (fig. 7) emerges when the Neogene 

events (fig. 6) are combined with paleomagnetic declinations from sites in the northwest sector (fig. 5), and both are 

coupled with thickness and facies templates of Sespe and 

Vaqueros Formations (figs. 3, 4). 

Back-Slip of Fault Separations

Creation of a palinspastic reconstruction required undoing 

a variety of fault movements. First, a crude restoration was 

made of the north-south and northeast-southwest shortening 

within the Los Angeles Basin and adjacent areas (Yerkes, 1972; 

Davis and others, 1989; Wright, 1991; Pratt and others, 1998; 

Shaw and Shearer, 1999; Oskin and others, 2000; Tsutsumi and 

others, 2001).

Back-slip to correct for right oblique reverse and strike 

slip on the Whittier Fault Zone and the continuation on the 

Elsinore Fault was next imposed (McCulloh and others, 2000). 

Contemporaneous back-slip was also applied to compensate 

for left oblique strike and reverse slip on the Raymond-Hollywood-Santa Monica Fault Zone (Jones and others, 1990; Pratt 

and others, 1998; McCulloh and others, 2001). Earlier left slip 

on the Benedict Canyon Fault (Hoots, 1931; Durrell, 1954) 

was assumed to join later left oblique reverse slip of the Santa 

Monica Fault Zone west of the concealed junction of these 

faults. We combine the two slips west of the junction and call 

for right back-slip of 16 km (10 miles), plus an unmeasured 

amount of composite dip back-slip on the Malibu Coast Fault. 

Fully equivalent restorations for the Malibu Coast and Anacapa 

Faults were not feasible, even though the linkage and kinship 

of these faults to the Santa Monica-Hollywood-Raymond zone 

of reverse, oblique, and left-slip active faults is widely recognized (Pratt and others, 1998, p. 480).

Post-late Pliocene right slip on the Newport-Inglewood 

Fault Zone is at least 1.2 km at some places (Wright, 1991, p. 

66). Older strike slip, possibly before 5 Ma, may be substantial 

(Hazenbush and Allen, 1958). Middle Miocene dip slip on an 

originally northeast-dipping normal “Wardlow” fault branch 

Figure 5.—Map of paleomagnetic declinations for rocks erupted or intruded before 10 Ma in the northwest sector compiled from published sources 

(numbered as in table 1), with major faults and selected geographic features. NIZ—Newport-Inglewood Fault Zone.

PACIFIC OCEAN

Anacapa Fault

Anacapa

Island

Point Mugu

Point Dume

1 2

3 4

5

6

7

8

9

10 11

Oak Ridge Fault

San Gabriel Fault

NIZ

119°W 118.5°

34°N

0 10 20 30

KILOMETERS

Benedict Cyn. F.

Verdugo F. Santa Susana Fault

Malibu Coast Fault

Lechuza Point

12
13

20 Ma 10 0

Net slip

(km)

n

L+r

n

R+r

R+r

r

r

?

FAULTS

?

? ? r

Whittier

Las Cienegas

Newport-Inglewood Zone

Benedict Canyon

Santa Monica - Malibu 

 Coast

Verdugo

Raymond-Hollywood

Oakridge-Santa Susana

Chino

AGE 

Type and period of displacement

? n

n R ?

n ?

9 R

2-3 r

2-3 R ?

2-3 L

16 L

3-4 n

?

? > 3.5 r

? 1 R

13-14 L

?

?

?

Monterey Park ("Elysian 

 Park fold and thrust")

IGNEOUS EPISODES

Anacapa Island

Glendora Volcanics

Western Santa Monica Mtns.

Central L.A. Basin

El Modeno Volcanics

BENTHIC 

 FORAMINIFERAL

 STAGES (Provincial)

EPOCH

AGE 20 Ma 0

? n L+r

NOTEWORTHY

 REGIONAL

 UNCONFORMITIES

Saucesian

Relizian

Luisian

Mohnian

"Delmontian"

Repettian

early late

EARLY MIDDLE LATE

MIOCENE PLIOCENE

EARLY

m l l

?

Eastern Santa Monica Mtns.

?

10

(Adapted from Barron and 

Isaacs, 2001, fig. 22.1)

Whittier diabase (Yerkes, 1972)

e

Figure 6.—Major fault separation estimates, noteworthy regionally developed unconformities (or depositional interruptions), and important 

igneous episodes of the greater Los Angeles region summarized in simplified form with a time framework. “R” and “L” indicate right-lateral 

and left-lateral strike slip, respectively; “n” and “r” indicate normal and reverse slip, respectively.

Preliminary Palinspastic Reconstruction
14 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

119°

118°45'

118°30'

34°15'

118°30'

33°30

119°

11

34°

ANACAPA

MALIBU

BACK-SLIPPED AND

COAST FAULT

FAULT

(BACK-ROTATED)

O

SS

S

BACK-ROTATED

? ?

?

? ?

?

?

�����

?

?

?

? ?

?

? ?

?

?

? ? ?

�������������������������������

�����������������������

�������������

������������������

����

����

����

����

����

����

����

����

����

����

����

����

����

����

����

���� ����

����

EXPLANATION

PRE-CRETACEOUS ROCKS

Outcrops of Peninsular Ranges Province basement lithologies

Outcrops of Santa Monica Slate and intrusive granodiorite

Area known or reasonably inferred to be floored by Catalina Schist

Area known or reasonably inferred to be floored by Peninsular Ranges

Province basement lithologies

Area where this reconstruction infers that the Santa Monica Mountains terrane

overrides Catalina Schist

CONTACT RELATIONS

Reconstructed basin margin

Erosional edge

Edge of marine facies

Gap generated by palinspastic reconstruction, suggesting

expression of present-day overthrusting

Important faults (long dash where uncertain, short

dash where inferred, and queried where doubtful)

Prospect well that provides critical insight (see appendix 3)

SESPE-VAQUEROS UNDIFFERENTIATED

(includes Trancas Formation)

Outcrops

Subsurface nonmarine only

Subsurface partly marine

Line of equal thickness in feet

(dashed and dotted where less certain)

60

����

����������

� � � �� ��

Figure 7.—Preliminary palinspastic reconstruction of the greater Los Angeles Basin region based on the 

paleodepositional templates for the northwest and southeast sectors (figs. 3, 4), paleomagnetic declinations
Uncertainties and Future Challenges 15

118°15'

33°45'

118°

117°45'

118°

118°15'

34°15'

118°

0'

118°45'

118°

33°15'

117°30'

117°30'

34°

MP

LC

BC

SM-H

SG

R

NIZ

W

E

W

?

?

?

?

? ?

? ?

? ?

?

?

?

?

? ?

?

60

���

����

���� ����

����

?

?

?

?

����

����

����

����

? ?

���

����

����

����

����

����

����

����

����

?

? ?

�������������������

E D G E O F S U B S U R F A C E C O N T R O L

? ?

? ? ?

?

? ?

����

? ?

See McCulloh and others

(2000, 2001) for palinspastic

reconstructions involving these

blocks

? ?

?

�����������

(fig. 5, table 1), and the deformations summarized on figure 6. MP—Monterey Park Fault; see figure 1 for other 

fault-name abbreviations.
16 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

of the Newport-Inglewood Fault Zone may exceed 0.5 km 

(Harris, 1958). Our preliminary reconstruction for the Newport-Inglewood Fault Zone removes 2 to 3 km of right slip.

The Las Cienegas Fault, which probably originated as 

a southwest-dipping normal fault in middle Miocene time, 

was reactivated as a northeast- to north-dipping reverse fault 

beginning roughly at 5 Ma (Schneider and others, 1996). 

This fault, known mainly through petroleum drill holes but 

mapped geophysically to the east of the Las Cienegas oil 

field as the “Huntington Park fault” (McMurdie and others, 

1973), shows a minimum reverse separation of about 2 to 3 

km and contributes to the northeast-southwest transpressive 

shortening previously mentioned. The amount of normal 

dip-slip separation that may have occurred during middle 

Miocene is highly uncertain and not addressed here. 

Evidence of middle Miocene extension along the Whittier 

Fault trend is indirect and summarized elsewhere (McCulloh 

and others, 2000), as is more concrete evidence for early 

normal faulting on the Verdugo Fault (McCulloh and others, 

2001). Back-slip to account for these weakly documented 

early extensions also has not been included in the preliminary reconstruction and probably has minimal impact on the 

restoration.

Restoration of Rotation

Incorporation of rotational evidence into our reconstruction is a challenge. Although an assumed constant clockwise rotation rate of “5.79 deg./m.y.” has been suggested 

for the western Santa Ynez Range northwest of our region 

(Luyendyk, 1991, fig. 7), there is no reason to suppose that 

the entire northwest sector fits that model. In fact, a very 

different approach (Dickinson, 1996, table 2) leads to the 

appealing result that the region is segmented with different 

segments having undergone different amounts of rotation 

(but at the constant rate of “5.8 ̊ ± 0.1 ̊ /m.y.”) that ceased at 

different times. An even more complicated history is conceivable, in which a mosaic of fault blocks in the northwest 

sector rotated semi-independently instead of the “56 ̊” or 

“77 ̊” averages for the pertinent “domains” of Dickinson 

(1996, fig. 9). 

Recognizing that published data allow for a range of 

possible interpretations, the following three assumptions are 

adopted for our reconstruction: (1) The entire body of northwest sector rocks older than17.4 Ma rotated 80 ̊ clockwise, 

the maximum supported by most data, at a constant rate 

from start to the present. All Trancas Formation and Zuma 

Volcanics between the Anacapa and Malibu Coast Faults also 

rotated 80 ̊. (2) The area of all Sespe Formation or older 

Cenozoic outcrops east to about Cahuenga Pass (longitude 

118° 18’ W) near the east end of the Santa Monica Mountains rotated clockwise only 40 ̊ since about 13 Ma. (3) The 

area at the easternmost end of the range may have rotated 

about 20 ̊ clockwise, but only since about 4 Ma. 

While other assumptions may prove correct, those outlined above seem to best fit available data. The preliminary 

reconstruction shown in figure 7 embodies the above rotation assumptions, together with the restorations of fault offsets previously discussed and summarized (fig. 6). 

Discussion

Most noteworthy in our preliminary reconstruction is 

the degree to which the templates of the Sespe-Vaqueros 

Formations fail to join, despite strong but possibly relatively superficial similarities. Very substantial gaps remain 

between the two partly erosional Sespe-Vaqueros basin 

margins and the separated (or separate?) marine-nonmarine 

facies limits, despite the substantial angular and translational restoration. Equally impressive, although strong 

similarities are evident in the isopach patterns for the two 

sectors, attempts to unify them spatially fail. Foremost 

in the failure is the fact that a projection of the combined 

Sespe-Vaqueros thickness in the northwest sector is 600-900 

m (2,000-3,000 ft) along the Malibu Coast Fault. Presumably this projected thickness must approach zero between 

the Anacapa and Malibu Coast Faults, where blocks of 

San Onofre Breccia (Woodford and Bailey, 1928) and finer 

Catalina Schist detritus were eroded during deposition of 

the Trancas Formation and parts of the “Lower Topanga” or 

“Topanga Canyon Formation” (Campbell and others, 1996). 

The Sespe-Vaqueros Formations of the southeast sector also 

thin toward the western edge of drill hole control to a minimum of less than 150 m (500 ft). Secondarily, after backrotation, the nearly east-west isopach trends of the northwest 

sector fail to parallel the similar (north-south) isopach trend 

of the southeast sector. An unobserved additional back-rotation of the northwestern sector of 20 ̊-25 ̊, or commensurate 

rotations of both sectors to total about 100 ̊, is needed to 

fully align isopach trends. Because we view these thickness 

trends as products of long-term tectonic control of alternating belts of subsidence and relative uplift before 17.4 Ma, 

their remaining divergence after back-rotation suggests that 

information may be missing and that our reconstruction 

therefore is deficient.

The absence of compellingly trustworthy magnetic declination data in the southeast sector also adds uncertainty 

to our restoration. Some results suggest counterclockwise 

rotation of 26o to 36o for Cretaceous and latest Paleocene 

strata of the northern Santa Ana Mountains (Morris and 

others, 1986, table 1). However, other results suggest “69o 

± 15o” clockwise rotation for latest Paleocene in the same 

area (Prothero and Lopez, 2001) and no rotation for Sespe 

Formation in the same general area (Prothero and Donohoo, 

2001). More and better data are needed.

The Newport-Inglewood Fault Zone is the northeastern 

limit of all known Catalina Schist in the region. Reconstructions calling for a Catalina Schist floor beneath the Los 

Angeles Basin northeast of the Newport-Inglewood fault zone 

are hypothetical (Crouch and Suppe, 1993; Bohannon and 

Geist, 1998) and model-dependent. Similarly, the present-day 

Malibu Coast Fault is also believed to be the northern limit of 
Uncertainties and Future Challenges 17

Catalina Schist (Yerkes and Campbell, 1979). The back-rotation of 80 ̊ used in our trial reconstruction still leaves an angle 

of about 60 ̊ between the restored outcrop course of the Santa 

Monica-Malibu Coast Fault and the present overall course of 

the Newport-Inglewood Fault Zone (fig. 7), assuming that no 

other horizontally substantial translations or other cryptic factors intervened. Evidence for greater back-rotation to explain 

this apparent misfit is lacking. 

Our preliminary reconstruction is similar to one proposed for 16 Ma by Hornafius and others (1986, fig. 9), 

even though respective underlying assumptions about fault 

offsets differ substantially. It is also similar to palinspastic 

reconstructions to 14 to 13 Ma of Luyendyk (1990, fig. 5a; 

1991, fig. 5) and, in some ways, to a more complex and 

comprehensive reconstruction to 19 Ma by Sorlien and 

others (1999, fig. 13B). Critical differences from our reconstruction are evident in the restoration described by Crouch 

and Suppe (1993, fig. 4 and p. 1421), not the least of which 

are “110 ̊” of clockwise rotation of the northwest block 

and “30 km” of left slip on the Malibu Coast-Raymond 

Fault Zone. However, the “110 ̊” of rotation of Crouch 

and Suppe (1993), while not based on pertinent observations and greater than our allowed 80 ̊, would lessen spatial 

discrepancies between the facies and thickness trends of 

our restored templates of the Sespe-Vaqueros Formations. 

The discordance between our restored trend of the Santa 

Monica-Malibu Coast Fault Zone and the trend of the Newport-Inglewood Fault Zone would also be reduced. Lastly, 

separate but possibly also critical differences are seen 

between our reconstruction and that of Bohannon and Geist 

(1998, fig. 14) which elaborates a central hypothesis of the 

Crouch and Suppe (1993) model.

Uncertainties and Future Challenges

Our work highlights several substantial uncertainties 

that stand in the way of reliably restoring the Los Angeles 

Basin region to its prerift configuration. We believe the 

following complexities and uncertainties impose possibly 

significant implications for any palinspastic reconstruction, 

including ours.

Limits of Paleomagnetic Declination Data

Presently available declination data for the central and 

western Santa Monica Mountains are immensely valuable 

but are largely restricted to volcanic rocks that probably are 

not older than 15.9 ± 0.8 Ma (Turner and Campbell, 1979, 

table 1 and p. E21, with recalculation using current decay 

constants). Do redbeds of the substantially older underlying 

Sespe Formation in the same area show the same or different rotations? 

No paleomagnetic declination data are published for 

rocks of the easternmost Santa Monica Mountains. Because 

the Topanga volcanics (Hoots, 1931) of that area have been 

shown to be 17.4 Ma (McCulloh and others, 2002), substantially older than the base of the Conejo Volcanics farther 

west, knowledge of postvolcanism rotation there would be 

exceptionally useful.

Deformed nonmarine Saugus Formation strata that are 

2.3 Ma and younger in the northernmost part of the northwest sector have undergone no rotation (Levi and Yeats, 

1993). Knowledge of the full areal extent of the unrotated 

rock mass and how far back in time that condition extends 

would help reconstruction efforts. Outcrops that are old 

enough and lithologically suitable for paleomagnetic determinations are limited. The Pacoima Hills (Oakeshott, 1958; 

Dibblee, 1991) in the northern San Fernando Valley, where 

nonmarine redbeds of Hemingfordian age Topanga Formation are overlain by middle Miocene Topanga volcanics, 

might offer possibilities.

Early Extensional Tectonism Along the Malibu 

Coast-Santa Monica Fault Zone

The Malibu Coast Fault Zone dips 30 ̊ to 70 ̊ to the 

north and records Pliocene and younger north-over-south 

thrusting where it is best known (Campbell and others, 

1996; Seeber and Sorlien, 2000). Just west of 118o 30’ W 

longitude at the coastline, the linked Santa Monica Fault 

Zone consists of two north-dipping breaks, a younger northern reverse fault, and an older southern reverse fault that 

appears to have been active only between 5 Ma and about 

1.5 Ma (Pratt and others, 1998). Another 10 km eastward, 

the Santa Monica Fault and its splays dip north and show 

Pliocene to Quaternary reverse slip, but probable “early 

to late Miocene normal” slip (Tsutsumi and others, 2001). 

Added to this complex record is evidence for 13 to 14 km of 

left strike-slip separation for the Raymond-Hollywood Fault 

segment probably since 5 Ma (McCulloh and others, 2001, 

p. 18) and another 2.4 km of left slip from the Benedict 

Canyon Fault (that joins west of longitude 118o 30’ W), thus 

totaling about 16 km of left slip feeding onto the Malibu 

Coast Fault. This contrasts with fairly compelling evidence of only about 12 km of left separation west of Point 

Dume, based on glaucophane-bearing breccia at Lechuza 

Point south of the fault and glaucophane-bearing sandstone 

just east of the mouth of Sycamore Canyon north of the 

westward extension of the fault. Possibly some left slip is 

on the Anacapa Fault. Alternatively, interactions between 

northwest-striking right-slip faults and west-striking left-slip 

zones might explain the 4 km difference.

In the central Santa Monica Mountains, the thick 

section of Cretaceous marine, Paleocene nonmarine and 

marine, and Eocene marine strata (Colburn, 1973; Carey 

and Colburn, 1978; Yerkes and Campbell, 1979; Colburn 

and others, 1981; Colburn, 1996; Campbell and others, 

1996), plus thousands of feet of nonmarine Sespe Formation strata, is present only north of the Malibu Coast Fault. 

South of the fault, Trancas Formation beds might be as 
18 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

young as slightly less than 19 Ma and most likely rest on 

Catalina Schist. Back slip of the 12 or 16 km of left-lateral 

strike movement on the Malibu Coast Fault does not alter 

these relationships. We judge from these and related facts 

that early movements on the Malibu Coast Fault probably 

occurred between 19 and 17.4 Ma and were extensional, 

with the north block (present coordinates) downthrown 

by more than 2 to 3 km. Presumably the Zuma and Tuna 

Canyon detachment faults (Campbell and others, 1996) are 

lesser but analogous structures within this extremely thick 

sedimentary section. Whether the early extensional slip 

included the Hollywood Fault Zone to the east is difficult to 

determine. Such slip is possible to likely because the oldest 

volcanic rocks in the region (17.4 Ma) probably occur only 

north of the fault zone (McCulloh and others, 2002), or 

west-northwest of it after our restoration.

Central Trough of the Los Angeles Basin 

The metasedimentary, metavolcanic, and metaplutonic 

rocks reached by drilling in the northwestern part of the 

Los Angeles Basin are important constraints on the mechanisms of basin opening and therefore on palinspastic reconstructions. Most of these rocks are extensively described 

(Schoellhamer and Woodford, 1951; Yerkes and others, 

1965, fig. 5 and p. A21-A24; Yeats, 1973; Sorenson, 1985; 

McCulloh and others, 2001, fig. 2, table 4). Their distribution 

limits the area of poorly known and unknown basin floor to 

the northwestern region of the central trough between the Las 

Cienegas Fault on the north and the Newport-Inglewood Fault 

Zone to the southwest. The exact nature of basement rocks 

and the deep overlying sedimentary units in this area of the 

Los Angeles Basin is poorly documented. Multiple modeldependent hypotheses have been advanced, either directly 

through a range of assumptions or interpretations, or indirectly through unstated inferences (McCulloh, 1960; Yerkes 

and others, 1965, figs. 5-7 and p. A24-A28; Crowell, 1974, 

especially p. 201-202; Crowell, 1987; Mayer, 1991; Redin, 

1991, fig. 4; Crouch and Suppe, 1993, p. 1419-1421 and fig. 

4; Langenheim and Jachens, 1996; Shaw and Suppe, 1996; 

Bohannon and Geist, 1998, fig. 14; Kaban and Mooney, 2001, 

fig. 11; Bjorklund and others, 2002). 

The presence of at least partly submarine middle 

Miocene volcanic rocks around the perimeter of the central trough encourages us to believe that trough evolution 

involved localized volcanic upwelling in the early subsidence stages (Crowell, 1987, p. 225; McCulloh and others, 

2002). This suggests localized extension in a restricted zone 

of rifting, possibly along breaks striking about N10o W, 

like those compiled from volcanic dike outcrops in the San 

Joaquin Hills by Yeats (1974, fig. 1). In the absence of more 

concrete and unequivocal evidence, these uncertainties will 

continue to permit a range of model-dependent constructs. 

However, the filled young central trough of the Los Angeles 

Basin south of the Las Cienegas Fault and west of the southeast sector most likely is a passive by-product of some form 

of extensional transrotation. Is it one of the “triangular or 

transrotational basins [that] open at the join between rotating and nonrotating crust in the deforming zone” (Luyendyk, 

1991, p. 1533)?

Junction of the Inglewood and Santa Monica 

Fault Zones 

Multiple subsurface complexities along the entire 

onshore trace of the Newport-Inglewood Fault Zone are 

not nearly as complicated as those near and at its northwest 

junction with the Santa Monica Fault Zone (Yeats, 1973, 

fig. 2; Lang and Dressen, 1975; Jacobson and Lindblom, 

1987; Wright, 1991, fig. 14; Schneider and others, 1996, 

fig. 8; Tsutsumi and others, 2001, fig. 2). A key uncertainty 

is whether the late right slip of 1.2 km on the NewportInglewood Fault Zone at Inglewood oil field (Wright, 1991, 

p. 66) breaks and offsets splays of the Santa Monica Fault 

along what is called the “West Beverly Hills lineament” 

(Tsutsumi and others, 2001) or finds its way instead onto 

the northeast-dipping Rancho fault breaks (of Lang and 

Dreesen, 1975, fig. 3) along the southwest margin of and 

beneath the Cheviot Hills oil field (Wright, 1991, fig. 14). 

Although other uncertainties in this northwestern corner of 

the Los Angeles Basin importantly influence our reconstruction, probably none is more consequential than these. The 

cross section through the “Inglewood fault?” north of the 

Cheviot Hills oil field of Tsutsumi and others (2001, fig. 

4, section G-G’) suggests that post-7.5 Ma right slip probably was absorbed by the “Rancho fault” (as suggested by 

Lang and Dreesen, 1975). If so, that right slip probably 

effectively cancels some left slip on the Santa Monica Fault 

Zone west of the Sawtelle oil field, where the Rancho and 

Santa Monica Fault Zones presumably merge (Wright, 1991, 

fig. 14). Separately, possible pre-7.5 Ma right slip on a 

throughgoing extension of the Inglewood Fault along the 

“West Beverly Hills lineament” could have evaded detection and might explain the presence (slightly farther east) of 

the singular subsurface occurrence of “Sespe” (Yerkes and 

others, 1965, fig. 5, p. A23) or “Paleocene” redbeds (Yeats, 

1973, p. 135; Tsutsumi and others, 2001, fig. 4E) overlain 

by volcanics and resting on “granite” in the Morgan Brown 

“Oil District U-6” No. 1 (appendix 1). 

Conclusion

This study was motivated by the need for a synoptic 

picture of the regional geology of coastal southern California 

prior to transrotation of the western Transverse Ranges and 

the concomitant opening of the Neogene Los Angeles Basin. 

Outcrop and exploration drill hole information were used to 

compile a regional map of the areal extent, thickness variations, and lithofacies of Eocene-lower Miocene Sespe and 

Vaqueros Formations plus their equivalents. Two separate 
19

sectors of the region emerged, each having distinctive thickness patterns and both exclusively nonmarine and partially 

marine facies depositional patterns. Taken together, the 

interfingering clastic formations extend over more than 2,000 

km2 in area and occupy more than 3,900 km3 in volume. 

Exploring how these two now-separate sectors may have 

been related before transrotation required that we assemble 

and use trustworthy published paleomagnetic declination data 

to retro-deform the region. This palinspastic reconstruction, 

a primary product of this study, also required coordinated use 

of information about movements on major fault zones.

The preliminary palinspastic reconstruction of figure 7 

will surely be modified and replaced. However, it is a step 

beyond prior reconstructions covering the same region and 

brings critical unanswered questions into focus. Understanding the time of emergence of Catalina Schist along the coast 

south of the Malibu Coast Fault is crucial. More precise 

dating of San Onofre Breccia along the Malibu Coast would 

provide new indirect limits on the mechanism responsible 

for exposing Catalina Schist to subaerial erosion prior to 

and accompanying the 17.4 Ma onset of rifting that initiated 

opening of the Los Angeles Basin. Improved understanding 

of the interactions between the Malibu Coast-Santa Monica 

Fault and the Newport-Inglewood Fault Zone would provide 

insights about the evolution of the central trough as well as 

the transrotational opening of the entire Los Angeles Basin. 

New or additional internally consistent paleomagnetic declination data from Cretaceous or Paleogene and younger strata 

in both the northwest and southeast sectors are needed to 

improve the preliminary model presented here. Lastly, the 

Sespe and Vaqueros templates themselves (figs. 3, 4) should 

help to refine and test future palinspastic reconstructions of 

the Los Angeles Basin region. 

Acknowledgments

Our work was possible because of the groundbreaking 

paleomagnetic declination results of M. J. Kamerling, B. P. 

Luyendyk, J. S. Hornafius, and J. C. Liddicoat. Geologic 

maps of the Santa Monica Mountains west of longitude 118 ̊ 

33’ 50” W by R. H. Campbell, R. F. Yerkes, and their associates provided an essential base for our work. Key drill 

hole samples and data were provided by the California Well 

Sample Repository, Aera Energy LLC (C. James), Chevron 

U.S.A. Inc. (J. Urbach), Nuevo Energy (N. Livingston), 

Unocal (R. Moag), and Mobil Oil Corp. The University of 

Texas at Dallas and R. E. Denison made valuable contributions. We thank personnel of the National Park Service for 

access to critical Santa Monica Mountains sites. Interactions 

with the following colleagues were especially helpful: S. P. 

Buck, R. H. Campbell, I. P. Colburn, S. W. Conkling, R. J. 

Enrico, J. S. Hornafius, J. W. Hillhouse, E. B. Lander, D. R. 

Prothero, J. E. Schoellhamer, J. G. Vedder, and R. F. Yerkes. 

We are especially grateful to R. H. Campbell, J. W. Hillhouse, and J. G. Vedder for careful and helpful reviews. C. L. 

Powell II and Zenon Valin kindly prepared the figures.

References

Addicott, W. O., 1977, Neogene chronostratigraphy of nearshore 

marine basins of the eastern Pacific, in Saito, Tsunemasa, 

and Ujiié, Hiroshi, eds., Proceedings of the First International Congress on Pacific Neogene Stratigraphy, Tokyo 

1976: International Union of Geological Sciences, Commission on Stratigraphy, Regional Committee on Pacific 

Neogene Stratigraphy, p. 151-175.

Arnold, R., 1907, New and characteristic species of fossil mollusks from the oil-bearing Tertiary formations of southern 

California: U. S. National Museum Proceedings, v. 32, p. 

525-546.

Atwater, T., and Stock, J., 1998, Pacific-North America 

platetectonics of the Neogene southwestern United States; 

an update: International Geology Review, v. 40, p. 375-

402.

Bailey, T. L., 1947, Origin and migration of oil into Sespe redbeds, 

California: American Association of Petroleum Geologists, 

v. 31, p. 1913-1935.

Barron, J. A., and Isaacs, C. M., 2001, Updated chronostratigraphic 

framework for the California Miocene, in Isaacs, C. M., and 

Rullkötter, Jürgen, eds., The Monterey Formation from 

rocks to molecules: New York, Columbia University Press, 

p. 393-395.

Bawden, G. W., Thatcher, W., Stein, R. S., Hudnut, K. W., and 

Peltzer, G., 2001, Tectonic contraction across Los Angeles 

after removal of groundwater pumping effects: Nature, v. 

412, p. 812-815.

Belyea, R. R., and Minch, J. A., 1989, Stratigraphy and depositional environments of the Sespe Formation, northern Santa 

Ana Mountains, California, in Colburn, I. P., Abbott, P. A., 

and Minch, J., eds., Conglomerates in basin analysis; A 

symposium dedicated to A. O. Woodford: Society of Economic Paleontologists and Mineralogists, Pacific Section, 

Book 62, p. 281-300.

Berry, A. L., Dalrymple, G. B., Lanphere, M. A., and Von Essen, 

J. C., compilers and editors, 1976, Summary of miscellaneous potassium-argon age measurements, U. S. Geological 

Survey, Menlo Park, California, for the years 1972-1974: 

U. S. Geological Survey Circular 727, 13 p.

Bjorklund, Tom, Burke, Kevin, Zhou, Hua-Wei, and Yeats, R. S., 

2002, Miocene rifting in the Los Angeles basin; evidence 

from the Puente Hills half-graben, volcanic rocks, and Pwave tomography: Geology, v. 30, p. 451-454.

Blake, G. H., 1983, Benthic foraminiferal paleoecology and 

biostratigraphy of the Vaqueros Formation, Big Mountain 

area, Ventura County, California, in Squires, R. L., and Filewicz, M. V., eds., Cenozoic geology of the Simi Valley area, 

southern California: Society of Economic Paleontologists 

and Mineralogists, Pacific Section, Fall Field Trip Volume 

and Guidebook, p. 173-182.

Blake, G. H., 1991, Review of the Neogene biostratigraphy and 

stratigraphy of the Los Angeles basin and implications for 

basin evolution, in Biddle, K. T., ed., Active margin basins: 

American Association of Petroleum Geologists Memoir 

52, p. 135-184.

References
20 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

Blundell, M. C., 1983, Depositional environments of the Vaqueros 

Formation, Big Mountain area, Ventura County, California, 

in Squires, R. L., and Filewicz, M. V., eds., Cenozoic geology of the Simi Valley area, southern California: Society of 

Economic Paleontologists and Mineralogists, Pacific Section, Fall Field Trip Volume and Guidebook, p. 161-172.

Bohannon, R. G., and Geist, Eric, 1998, Upper crustal structure 

and Neogene tectonic development of the California Continental Borderland: Geological Society of America Bulletin, 

v. 110, p. 779-800.

California Division of Oil and Gas, 1975, 60th Annual report of 

the state oil and gas supervisor— 1974: California Division 

of Oil and Gas, Report no. PR06, p. 32.

Calvano, Gino, Lander, E. B., Whistler, D. P., Roeder, M. A., 

Walsh, S. L., and Wagner, H. M., 2003, Recognition of a 

major unconformity in the middle Eocene to lower Miocene, nonmarine Sespe Formation, northern Santa Ana 

Mountains, Orange County, CA: Paleo Bios, v. 23, supplement to no. 1, p. 1.

Campbell, R. H., and Yerkes, R. F., 1979, Stratigraphic nomenclature of the central Santa Monica Mountains, Los Angeles 

County, California: U. S. Geological Survey Bullletin 

1457-E, 31 p., 3 plates.

Campbell, R. H., Yerkes, R. F., and Wentworth, C. M., 1966, 

Detachment faults in the central Santa Monica Mountains, 

California: U. S. Geological Survey Professional Paper 

550-C, p. C1-C11.

Campbell, R. H., Blackerby, B. A., Yerkes, R. F., Schoellhamer, J. 

E., Birkeland, R. W., and Wentworth, C. W., 1996, Geologic 

map of the Point Dume quadrangle, Los Angeles County, 

California: U. S. Geological Survey Map GQ-1747, scale 

1:24,000.

Carey, S. M., and Colburn, I. P., 1978, Late Cretaceous sedimentation in the Santa Monica Mountains, California, 

in Howell, D. G., and McDougall, K. A., eds., Mesozoic 

paleogeography of the western United States: Society of 

Economic Paleontologists and Mineralogists, Pacific Section, p. 547-558.

Castro, M. J., 1975, Mahala field, in Truex, J. N., ed., A tour of 

the oil fields of the Whittier fault zone, Los Angeles basin, 

Calif.: American Association of Petroleum Geologists, Society of Exploration Geophysicists, and Society of Economic 

Paleontologists and Mineralogists, Pacific Sections, Joint 

Annual Field Trip, April 2, 1975, p. 73-76. 

Colburn, I. P., 1973, Stratigraphic relations of the southern 

California Cretaceous strata, in Colburn, I. P., and Fritsche, 

A. E., eds., Cretaceous stratigraphy of the Santa Monica 

Mountains and Simi Hills: Society of Economic Paleontologists and Mineralogists, Pacific Section, Fall Field Trip 

Guidebook, p. 45-73.

Colburn, I. P., 1996, Stratigraphy and sedimentary structures of 

the Paleogene successions in the west central Santa Monica 

Mountains, Los Angeles County, California, in Abbott, P. 

L., and Cooper, J. D., eds., Field Conference Guide 1996: 

American Association of Petroleum Geologists, Pacific 

Section, GB 73, and Society of Economic Paleontologists 

and Mineralogists, Pacific Section, Book 80, p. 93-116.

Colburn, I. P., West, E. R., and Carey, S. Mc.D., 1981, Conglomerates of the Chatsworth Formation; a discussion of 

petrology and provenance, in Link, M. H., Squires, R. L., 

and Colburn, I. P., eds., Simi Hills Cretaceous turbidites, 

southern California: Society of Economic Paleontologists 

and Mineralogists, Pacific Section, p. 75-88.

Crouch, J. K., and Suppe, J., 1993, Late Cenozoic tectonic 

evolution of the Los Angeles basin and inner California 

borderland; a model for core-complex-like crustal extension: Geological Society of America Bulletin, v. 105, p. 

1415-1434.

Crowell, J. C., 1974, Origin of late Cenozoic basins in southern 

California, in Dickinson, W. R., ed., Tectonics and sedimentation: Society of Economic Paleontologists and Mineralogists Special Publication No. 22, p. 190-204.

Crowell, J. C., 1987, Late Cenozoic basins of onshore southern 

California; complexity is the hallmark of their tectonic 

history, in Ingersoll, R. V., and Ernst, W. G., eds., Cenozoic basin development of coastal California: Englewood 

Cliffs, New Jersey, Prentice-Hall, Inc., Rubey Volume VI, 

p. 208-241.

Daniel-Lyle, L., 1995, Depositional environment and 

paleogeography of the lower Miocene Vaqueros Formation, Santa Ana Mountains, California, in Fritsche, A. 

E., ed., Cenozoic paleogeography of the western United 

States–II: Society for Sedimentary Geology, Pacific Section, Book 75, p. 9-21.

Daviess, S. N., and Woodford, A. O., 1949, Geology of the northwestern Puente Hills, Los Angeles County, California: U. S. 

Geological Survey Oil and Gas Investigations Preliminary 

Map 83, scale 1:12,000.

Davis, T. L., Namson, J., and Yerkes, R. F., 1989, A cross section of the Los Angeles area; seismically active fold and 

thrust belt, the 1987 Whittier Narrows earthquake, and 

earthquake hazard: Journal of Geophysical Research, v. 

94, p. 9644-9664.

Dibblee, T. W., Jr., 1982, Geology of the Santa Monica Mountains and Simi Hills, southern California, in Fife, D. L., 

and Minch, J. A., eds., Geology and mineral wealth of the 

California Transverse Ranges: South Coast Geological 

Society, Inc., Annual Symposium and Guidebook Number 

10, p. 94-130.

Dibblee, T. W., Jr., 1991, Geologic map of the San Fernando and 

Van Nuys (north 1/2) quadrangles, Los Angeles County, 

California: Dibblee Geological Foundation, map DF-33, 

scale 1:24,000.

Dibblee, T. W., Jr., and Ehrenspeck, H. E., 1990, Geologic map 

of the Point Mugu and Triunfo Pass Quadrangles, Ventura 

and Los Angeles Counties, California: Dibblee Geological 

Foundation, map DF-29, scale 1:24,000.

Dickinson, W. R., 1996, Kinematics of transrotational tectonism 

in the California Transverse Ranges: Geological Society of 

America Special Paper 305, 46 p.

Durham, D. L., and Yerkes, R. F., 1964, Geology and oil resources 

of the eastern Puente Hills area, southern California: U. S. 

Geological Survey Professional Paper 420-B, 62 p.

Durrell, C., 1954, Geology of the central Santa Monica Moun-
21

tains, Los Angeles and Ventura Counties, in Jahns, R. H., 

ed., Geology of southern California: California Division of 

Mines Bulletin 170, map sheet 8, scale 1:125,000.

Eaton, G. P., 1958, Miocene volcanic activity in the Los Angeles 

basin, in Higgins, J. W., ed., A guide to the geology and oil 

fields of the Los Angeles and Ventura regions: American 

Association of Petroleum Geologists, Pacific Section, p. 

55-61.

Flack, M. E., 1993, Depositional environments of the “Topanga 

Canyon” Formation, the Encinal Tongue of the Rincon 

Shale, and the Fernwood Tongue of the Sespe Formation, 

Central Santa Monica Moutains, California, in Weigand, P. 

W., Fritsche, A. E., and Davis, G. E., eds., Depositional and 

volcanic environments of middle Tertiary rocks in the Santa 

Monica Mountains, southern California: Society for Sedimentary Geology, Pacific Section, Book 72, p. 45-74.

Fritsche, A. E., 1993, Middle Tertiary stratigraphic terminology 

for the Santa Monica Mountains, southern California, in

Weigand, P. W., Fritsche, A. E., and Davis, G. E., eds., 

Depositional and volcanic environments of middle Tertiary 

rocks in the Santa Monica Mountains, southern California: 

Society for Sedimentary Geology, Pacific Section, Book 

72, p. 1-12.

Fritsche, A. E., 1998, Miocene paleogeography of southwestern 

California and its implications regarding basin terminology: 

International Geology Review, v. 40, p. 452-470.

Gaede, V. F., 1969, Prado-Corona oil field: California Division of 

Oil and Gas Resources, California Oilfields—Summary of 

Operations, v. 55, no. 1, p. 23-29.

Goodban, F. R., 1958, San Clemente oil field, in Higgins, J. W., 

ed., A guide to the geology and oil fields of the Los Angeles 

and Ventura regions: Los Angeles, California, American 

Association of Petroleum Geologists, Pacific Section, p. 

145-148.

Gray, C. H., Jr., 1961, Geology and mineral resources of the 

Corona South quadrangle: California Division of Mines 

and Geology Bulletin 178, 120 p.

Hall, E. A., Barker, C. T., and Rutherford, V. E., 1975, Geology of 

the Torrey Canyon, Oakridge, Santa Susana, South Tapo, 

and Tapo Ridge oil fields, and the nearby area, Ventura 

County, California: American Association of Petroleum 

Geologists, Pacific Section, Spring Field Trip Guidebook 

No. 40, 12 p.

Harris, P. B., 1958, Long Beach Airport pool, in Higgins, J. W., 

ed., A guide to the geology and oil fields of the Los Angeles 

and Ventura regions: Los Angeles, California, American 

Association of Petroleum Geologists, Pacific Section, p. 

75-77.

Hauksson, E., and Jones, L. M., 1989, The 1987 Whittier Narrows 

earthquake sequence in Los Angeles, southern California; 

seismological and tectonic analysis: Journal of Geophysical 

Research, v. 94, p. 9569-9589.

Hauksson, E., Jones, L. M., and Hutton, K., 1995, The 1994 

Northridge earthquake sequence in California; seismological and tectonic aspects: Journal of Geophysical Research, 

v. 100, n. B7, p. 12335-12355.

Hazenbush, G. C., and Allen, D. R., 1958, Huntington Beach 

oil field: California Division of Oil and Gas Resources, 

California Oilfields-Summary of Operations, v. 44, no. 1, 

p. 13-25.

Hill, M. L., 1971, Newport-Inglewood zone and Mesozoic subduction, California: Geological Society of America Bulletin, 

v. 82, p. 2957-2962.

Hoots, H. W., 1931, Geology of the eastern part of the Santa 

Monica Mountains, Los Angeles County, California: U. S. 

Geological Survey Professional Paper 165-C, p. 83-134, 

map scale 1:24,000.

Hornafius, J. S., 1985, Neogene tectonic rotation of the Santa Ynez 

Range, Western Transverse Ranges, California, suggested 

by paleomagnetic investigation of the Monterey Formation: 

Journal of Geophysical Research, v. 90, p. 12503-12522.

Hornafius, J. S., Luyendyk, B. P., Terres, R. R., and Kamerling, 

M J., 1986, Timing and extent of Neogene tectonic rotation 

in the western Transverse Ranges, California: Geological 

Society of America Bulletin, v. 97, p. 1476-1487.

Howard, J. L., 1989, Conglomerate clast populations of the 

Upper Paleogene Sespe Formation, southern California, 

in Colburn, I. P., Abbott, P. L., and Minch, J. A., eds., Conglomerates in basin analysis; a symposium dedicated to A. 

O. Woodford: Society of Economic Paleontologists and 

Mineralogists, Pacific Section, Book 62, p. 269-280.

Howard, J. L., 2000, Provenance of quartzite clasts in the EoceneOligocene Sespe Formation: paleogeographic implications 

for southern California and the ancestral Colorado River: 

Geological Society of America Bulletin, v. 112, p. 1635-

1649.

Howard, J. L., and Lowry, W. D., 1995, Medial Cenozoic 

paleogeography of the Los Angeles area, southwestern 

California, and adjacent parts of the United States, in Fritsche, A. E., ed., Cenozoic paleogeography of the western 

United States–II: Society of Economic Paleontologists and 

Mineralogists, Pacific Section, Book 75, p. 22-41.

Huftile, G. J., 1988, Structural geology of the Chaffee Canyon oil 

field, Ventura County, California, in Sylvester, A. G., and 

Brown, G. C., Santa Barbara and Ventura basins: Ventura, 

California, Coast Geological Society, Guidebook 64, p. 

125-132.

Ingersoll, R. V., and Rummelhart, P. E., 1999, Three-stage evolution of the Los Angeles basin, southern California: Geology, 

v. 27, p. 593-596.

Irving, E. M., 1937, Tourmalinization in the vicinity of the Cajalco 

Tin Mine, near Corona, California [abs.]: Proceedings of the 

Geological Society of America for 1936, p. 300-301.

Jacobson, J. B., and Lindblom, R. G., 1987, The east Beverly Hills, 

south Salt Lake and San Vicente fields—examples of urban 

oil development, Los Angeles, California, in Wright, T., 

and Heck, R., eds., Petroleum geology of coastal southern 

California: American Association of Petroleum Geologists, 

Pacific Section, p., 32-30.

Jones, L. M., Sieh, K. E., Hauksson, E., and Hutton, L. K., 1990, 

The 3 December 1988 Pasadena, California earthquake; 

evidence for strike-slip motion on the Raymond fault: Seismological Society of America Bulletin, v. 80, p. 474-482.

Junger, A., and Wagner, H. C., 1977, Geology of the Santa Monica 

References
22 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

and San Pedro Basins, California Continental Borderland: 

U. S. Geological Survey Miscellaneous Field Studies Map 

MF-820, 10 p., 5 sheets, scale 1:250,000.

Kaban, M. K., and Mooney, W. D., 2001, Density structure of 

the lithosphere in the southwestern United States and its 

tectonic significance: Journal of Geophysical Research, v. 

106, p. 721-739.

Kamerling, M. J., and Luyendyk, B. P., 1979, Tectonic rotations 

of the Santa Monica Mountains region, western Transverse Ranges, California, suggested by paleomagnetic 

vectors: Geological Society of America Bulletin, v. 90, p. 

331-337.

Kamerling, M. J., and Luyendyk, B. P., 1985, Paleomagnetism 

and Neogene tectonics of the northern Channel Islands, 

California: Journal of Geophysical Research, v. 90, n. B14, 

p. 12485-12502.

Kelly, T. S., 1990, Biostratigraphy of Uintan and Duchesnean 

land mammal assemblages from the middle member of the 

Sespe Formation, Simi Valley, California: Natural History 

Museum of Los Angeles County Contributions in Science, 

Number 419, p. 1-42.

Kew, W. S. W., 1923, Geologic formations of a part of southern 

California and their correlation: American Association of 

Petroleum Geologists Bulletin, v. 7, p. 411-420.

Lander, E. B., 1983, Continental vertebrate faunas from the upper 

member of the Sespe Formation, Simi Valley, California, 

and the terminal Eocene event, in Squires, R. R., and Filewicz, M. V., eds., Cenozoic geology of the Simi Valley area, 

southern California: Society of Exploration Paleontologists 

and Mineralogists, Pacific Section, Fall Field Trip Volume 

and Guidebook, p., 142-153.

Lander, E. B., 1994, Recalibration and causes of marine regressive-transgressive cycle recorded by middle Eocene to 

lower Miocene nonmarine Sespe Formation, southern 

California continental plate margin, in Fritsche, A. E., ed., 

Sedimentology and paleontology of Eocene rocks in the 

Sespe Creek area, Ventura County, California: Society 

for Sedimentary Geology, Pacific Section, Book 74, p. 

79-88.

Lander, E. B., Weigand, P. W., Fritsche, A. E., Alderson, J. M., and 

Iriondo, Alexander, 2003, New 40Ar/39Ar age determinations 

for two tuffs in the Piuma (upper) Member of the continental 

Sespe Formation, central Santa Monica Mountains, California [abs.]: American Association of Petroleum Geologists, 

Pacific Section, Conference Program & Abstracts, May 

19-24, Long Beach, p. 37.

Lane, C. L., 1989, Comparison of arenite and conglomerate clast 

petrology; utility in provenance determinations, southern 

California, in Colburn, I. P., Abbott, P. L., and Minch, 

John, eds., Conglomerates in basin analysis; a symposium dedicated to A. O. Woodford: Society of Economic 

Paleontologists and Mineralogists, Pacific Section, v. 62, 

p. 255-267.

Lang, H. R., and Dreessen, R. S., 1975, Subsurface structure of 

the northwestern Los Angeles basin: California Division 

of Oil and Gas Resources, Technical Papers, Report TP01, 

p. 15-21.

Langenheim, V. E., and Jachens, R. C., 1996, Gravity data collected along the Los Angeles regional experiment (LARSE) 

and preliminary model of regional density variations in 

basement rocks, southern California: U. S. Geological 

Survey Open File Report 96-682, 25 p.

Levi, S., and Yeats, R. S., 1993, Paleomagnetic constraints on the 

initiation of uplift on the Santa Susana fault, western Transverse Ranges, California: Tectonics, v. 12, p. 688-702.

Levi, S., and Yeats, R. S., 2001, Crustal fragmentation and Neogene 

rotations in the east Ventura basin and San Fernando Valley, 

southern California [abs.]: Geological Society of America, 

Abstracts with Programs, v. 33, no. 3, p. A-63.

Liddicoat, J. C., 1988, Paleomagnetism of the Zuma Volcanics, 

Point Dume, Los Angeles County, California: California 

Geology, v. 41, p. 243-247.

Liddicoat, J. C., 1990, Tectonic rotation of the Santa Ynez Range, 

California, recorded in the Sespe Formation: Geophysical 

Journal International, v. 102, p. 739-745.

Liddicoat, J. C., 2001, Paleomagnetism of the Sespe Formation 

(Eocene-Oligocene), Ventura and Santa Barbara Counties, 

California, in Prothero, D. R., ed., Magnetic stratigraphy 

of the Pacific Coast Cenozoic: Society for Sedimentary 

Geology, Pacific Section, Book 91, p. 144-153.

Link, M. H., and Dibblee, T. W., Jr., 1987, Field trip guide to the 

Ventura Basin area, in Link, M. H., ed., Ventura basin; 

geologic introduction and field trip guidebook: American 

Association of Petroleum Geologists, Pacific Section, 

October 17-18, 1987, p. 23-36.

Loel, W., and Corey, W. H., 1932, The Vaqueros Formation, Lower 

Miocene of California: University of California Publications, Bulletin of Department of Geological Sciences, v. 

22, no. 3, p. 31-410.

Lucas, S. G., Whistler, D. P., and Wagner, H. M., 1997, Giant 

Entelodont (Mammalia Artiodactyla) from the early Miocene of southern California: Natural History Museum of 

Los Angeles County, Contributions in Science, no. 466, 

p. 1-9.

Ludtke, Josh, and Prothero, D. R., 2003, Magnetic stratigraphy 

of the Eocene-Oligocene-Miocene Sespe-Vaqueros Formations, northern Orange County, CA: Paleo Bios, v. 23, 

supplement to no. 1, p. 5.

Luyendyk, B. P., 1990, Neogene-age fault slip in the continental 

transform zone in Southern California: Annales Tectonicae, 

Special Issue v. IV, p. 24-34.

Luyendyk, B. P., 1991, A model for Neogene crustal rotations, 

transtension, and transpression in southern California: 

Geological Society of America Bulletin, v. 103, p. 1528-

1536.

Luyendyk, B. P., and Hornafius, J. S., 1987, Neogene crustal 

rotations, fault slip, and basin development in southern 

California, in Ingersoll, R. V., and Ernst, W. G., eds., Cenozoic basin development of coastal California: Englewood 

Cliffs, New Jersey, Prentice-Hall, Inc., Rubey Volume VI, 

p. 260-283.

Luyendyk, B. P., Gans, P. B., and Kamerling, M J., 1998, 40Ar/39Ar 

geochronology of southern California Neogene volcanism, 

in Weigand, P. W., ed., Contributions to the geology of the 
23

northern Channel Islands, southern California: American 

Association of Petroleum Geologists, Pacific Section, MP45, p. 9-35.

Mason, M. A., and Swisher, C. C., III, 1989, New evidence for 

the age of the South Mountain local fauna, Ventura County, 

California: Natural History Museum of Los Angeles County 

Contributions in Science, no. 410, 9 p.

Mayer, L., 1991, Central Los Angeles basin; subsidence and thermal implications for tectonic evolution, in Biddle, K. T., ed., 

Active margin basins: American Association of Petroleum 

Geologists Memoir 52, p. 185-195.

McCulloh, T. H., 1960, Gravity variations and the geology of the 

Los Angeles basin, California: U. S. Geological Survey 

Professional Paper 400-B, p. B320-B325.

McCulloh, T. H., Beyer, L. A., and Enrico, R. J., 2000, Paleogene 

strata of the eastern Los Angeles basin, California; 

paleogeography and constraints on Neogene structural 

evolution: Geological Society of America Bulletin, v. 112, 

p. 1155-1178.

McCulloh, T. H., Beyer, L. A., and Morin, R. W., 2001, Mountain 

Meadows Dacite: Oligocene intrusive complex that welds 

together the Los Angeles Basin, northwestern Peninsular 

Ranges, and central Transverse Ranges, California: U. S. 

Geological Survey Professional Paper 1649, 34 p.

McCulloh, T. H., Fleck, R. J., Denison, R. E., Beyer, L. A., and 

Stanley, R. G., 2002, Age and tectonic significance of volcanic rocks in the northern Los Angeles Basin, California: 

U. S. Geological Survey Professional Paper 1669, 24 p.

McMurdie, D. S., Taylor, J. C., and Truex, J. N., compilers, 1973, 

Contours on top Miocene, southern Los Angeles basin, in

Metropolitan oil fields and their environmental impact: 

American Association of Petroleum Geologists, Society of 

Exploration Paleontologists and Mineralogists, and Society 

of Exploration Geophysicists, Pacific Sections, Guidebook 

Trip 2, approximate scale 1:111,600.

Merriam, C. W., 1941, Fossil turritellas from the Pacific Coast 

region of North America: University of California Publications, Bulletin of the Department of Geological Sciences, 

v. 26, no. 1, p. 1-214. 

Minch, J. A., Howard, J. L., and Belyea, R. R., 1989, Sespe 

Formation conglomerates in the northern Santa Ana and 

Santa Monica Mountains; a field trip guide, in Colburn, 

I. P., Abbott, P. L., and Minch, J., eds., Conglomerates in 

basin analysis; a symposium dedicated to A. O. Woodford: 

Society of Economic Paleontologists and Mineralogists, 

Pacific Section, book 62, p. 301-312.

Molnar, P., and Gipson, J. M., 1994, Very long baseline interferometry and active rotations of crustal blocks in the Western 

Transverse Ranges, California: Geological Society of 

America Bulletin, v. 106, p. 594-606.

Morris, L. K., Lund, S. P., and Bottjer, D. J., 1986, Palaeolatitude 

drift history of displaced terranes in southern and Baja 

California: Nature, v. 321, p. 844-847. 

Nagle, H. E., and Parker, E. S., 1971, Future oil and gas potential 

of onshore Ventura basin, California, in Cram, I. H., ed., 

Future petroleum provinces of the United States—their 

geology and potential: American Association of Petroleum 

Geologists, Memoir 15, p. 254-297.

Nicholson, C., Sorlien, C. C., Atwater, T., Crowell, J. C., and 

Luyendyk, B. P., 1994, Microplate capture, rotation of 

the western Transverse Ranges, and initiation of the San 

Andreas transform as a low-angle fault system: Geology, 

v. 22, p. 491-495.

Nourse, J. A., Weigand, P. W., and Hazelton, G. B., 1998, Igneous 

and tectonic response of the eastern San Gabriel Mountains 

to Neogene extension and rotation of the Transverse Ranges 

block, in Behl, R. J., ed., Guidebook to field trip No. 10, 

94th Annual Meeting, Cordilleran Section of the Geological 

Society of America, p. 10-1 to 10-15.

Oakeshott, G. B., 1958, Geology and mineral deposits of San 

Fernando Quadrangle, Los Angeles County, California: 

California Division of Mines Bulletin 172, 147 p.

Oborne, J. G., 1993, Stratigraphy and depositional environments of 

the Vaqueros Formation, central Santa Monica Mountains, 

California, in Weigand, P. W., Fritsche, A. E., and Davis, G. 

E., eds., Depositional and volcanic environments of middle 

Tertiary rocks in the Santa Monica Mountains, southern 

California: Society for Sedimentary Geology, Pacific Section, Book 72, p. 25-44.

Oskin, Michael, Sieh, Kerry, Rockwell, T., Miller, G., Guptill, 

P., Curtis, M., McAardle, S., and Elliot, P., 2000, Active 

parasitic folds on the Elysian Park anticline; implications for 

seismic hazard in central Los Angeles, California: Geological Society of America Bulletin, v. 112, p. 693-707.

Paschall, R. H., and Off, T., 1959, San Gabriel fault problem in the 

Castaic area: Ventura, California, Coast Geological Society, 

Occasional Papers no. 1, p. 1-8.

Paschall, R. H., and Off, T., 1961, Dip-slip versus strike-slip 

movement on the San Gabriel fault, southern California: 

American Association of Petroleum Geologists Bulletin, v. 

45, p. 1941-1956.

Pinter, Nicholas, Lueddecke, S. B., Keller, E. A., and Simmons, 

K. R., 1998, Late Quaternary slip on the Santa Cruz Island 

fault, California: Geological Society of America Bulletin, 

v. 110, p. 711-722.

Pratt, T. L., Dolan, J. F., Odum, J. K., Stephenson, W. J., Williams, 

R. A., and Templeton, M. E., 1998, Multiscale seismic imaging of active fault zones for hazard assessment: a case study 

of the Santa Monica fault zone, Los Angeles, California: 

Geophysics, v. 63, p. 479-489.

Prothero, D. R., and Donohoo, L. L., 2001, Magnetic stratigraphy 

of the lower Miocene (early Hemingfordian) Sespe-Vaqueros Formations, Orange County, California, in Prothero, D. 

R., ed., Magnetic Stratigraphy of the Pacific Coast Cenozoic: Society for Sedimentary Geology, Pacific Section, 

Book 91, p. 242-253.

Prothero, D. R., and Lopez, R. A., 2001, Magnetic stratigraphy 

and tectonic rotation of the upper Paleocene Silverado 

Formation, Orange, County, California: in Prothero, D. R., 

ed., Magnetic Stratigraphy of the Pacific Coast Cenozoic: 

Society for Sedimentary Geology, Pacific Section, Book 

91, p. 27-36.

 Prothero, D. R., Howard, J. L., and Dozier, T. H. H., 1996, Stratigraphy and paleomagnetism of the Upper Middle Eocene 

References
24 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California

to Lower Miocene (Uintan to Arikareean) Sespe Formation, 

Ventura County, California, in Prothero, D. R., and Emry, 

R. J., eds., The Terrestrial Eocene-Oligocene transition in 

North America: Cambridge University Press, p. 171-188.

Redin, T., 1991, Oil and gas production from submarine fans of 

the Los Angeles basin, in Biddle, K. T., ed., Active margin 

basins: American Association of Petroleum Geologists 

Memoir 52, p. 239-259.

Rumelhart, P. E., and Ingersoll, R. V., 1997, Provenance of the 

Upper Miocene Modelo Formation and subsidence analysis 

of the Los Angeles basin, southern California; implications 

for paleotectonic and paleogeographic reconstructions: 

Geological Society of America Bulletin, v. 109, p. 885-

899.

Schneider, C. L., Hummon, C., Yeats, R. S., and Huftile, G. L., 

1996, Structural evolution of the northern Los Angeles 

basin, California, based on growth strata: Tectonics, v. 15, 

p. 341-355.

Schoellhamer, J. E., and Woodford, A. O., 1951, The floor of the 

Los Angeles basin, Los Angeles, Orange, and San Bernardino Counties, California: U. S. Geological Survey Oil 

and Gas Investigations Map OM-117.

Schoellhamer, J. E., Vedder, J. G., Yerkes, R. F., and Kinney, D. 

M., 1981, Geology of the northern Santa Ana Mountains, 

California: U. S. Geological Survey Professional Paper 

420-D, 109 p.

Seeber, Leonardo, and Sorlien, C. C., 2000, Listric thrusts in the 

western Transverse Ranges, California: Geological Society 

of America Bulletin, v. 112, p. 1067-1079.

Seedorf, D. C., 1983, Upper Cretaceous through Eocene subsurface stratigraphy, Simi Valley and adjacent regions, California, in Squires, R. L., and Filewicz, M. V., eds., Cenozoic 

geology of the Simi Valley area, southern California: Society of Economic Paleontologists and Mineralogists, Pacific 

Section, volume and guidebook, p. 109-128.

Shaw, J. H., and Shearer, P. M., 1999, An elusive blind-thrust 

fault beneath metropolitan Los Angeles: Science, v. 283, 

p. 1516-1518.

Shaw, J. H., and Suppe, J., 1996, Earthquake hazards of active 

blind-thrust faults under the central Los Angeles basin, 

California: Journal of Geophysical Research, v. 101, no. 

B4, p. 8623-8642.

Shelton, J. S., 1954, Glendora volcanic rocks, Los Angeles basin, 

California: Geological Society of America Bulletin, v. 66, 

p. 45-90.

Shields, K. E., 1978, Faults along the northwestern margin of the 

San Fernando Valley, Los Angeles County, California, in

Lamar, D. L., field trip chairman, Geologic Guide and engineering geology case histories, Los Angeles Metropolitan 

Area: Association of Engineering Geologists, First Annual 

Section Conference, p. 44-52.

Simonson, R. R., 1937, Conglomerates of the Sespe and Topanga 

formations of Dry Canyon quadrangle, Santa Monica 

Mountains, California [abs.]: Proceedings of the Geological 

Society of America for 1936, p. 304-305.

Smith, J. T., 1991, Cenozoic giant pectinids from California and the 

Tertiary Caribbean Province; Lyropecten, “Macrochlamis,” 

Vertipecten, and Nodipecten species: U. S. Geological 

Survey Professional Paper 1391, 155 p., 38 plates.

Soper, E. K., 1938, Geology of the central Santa Monica Mountains: California Division of Mines, Journal of Mines and 

Geology Report, v. 34, p. 131-180.

Sorensen, S., 1985, Petrologic evidence for Jurassic, island-arclike basement rocks in the southwestern Transverse Ranges 

and California Continental Borderland: Geological Society 

of America Bulletin, v. 96, p. 997-1006.

Sorlien, C. C., Nicholson, Craig, and Luyendyk, B. P., 1999, Miocene extension and post-Miocene transpression offshore of 

south-central California: U. S. Geological Survey Bulletin 

1995-Y, 38 p.

Sorlien, C. C., Gratier, J.-P., Luyendyk, B. P., Hornafius, J. S., and 

Hopps, T. E., 2000, Map restoration of folded and faulted 

late Cenozoic strata across the Oak Ridge fault, onshore 

and offshore Ventura basin, California: Geological Society 

of America Bulletin, v. 112, p. 1080-1090.

Stock, C., 1948, Pushing back the history of land mammals in 

western North America: Geological Society of America 

Bulletin, v. 59, p. 327-332.

Stuart, C. J., 1976, Source terrane of the San Onofre Breccia—preliminary notes, in Howell, D. G., ed., Aspects of the geologic 

history of the California Continental Borderland: American 

Associate of Petroleum Geologists, Pacific Section, Miscellaneous Publication 24, p. 309-325.

Stuart, C. J., 1979, Middle Miocene paleogeography of coastal 

southern California and the California Borderland—evidence from schist-bearing sedimentary rocks, in Armentrout, J. M., Cole, M. R., and TerBest, H., Jr., Cenozoic 

paleogeography of the western United States: Society 

of Economic Paleontologists and Mineralogists, Pacific 

Section, Pacific Coast Paleogeography Symposium 3, p. 

29-44.

Taylor, G. E., 1984, Depositional environments of the Eocene 

through Oligocene Sespe Formation in the northern Simi 

Valley area, Ventura County, California: California State 

University Northridge, M. S. thesis, 74 p.

Truex, J. N., 1976, Santa Monica and Santa Ana Mountains—relation to Oligocene Santa Barbara basin: American Association Petroleum Geologists Bulletin, v. 60, p. 65-86.

Tsutsumi, H., Yeats, R. S., and Huftile, G. J., 2001, Late Cenozoic 

tectonics of the northern Los Angeles fault system: Geological Society of America Bulletin, v. 113, p. 454-468.

Turner, D. L., and Campbell, R. H., 1979, Age of the Conejo 

Volcanics, in Yerkes, R. F., and Campbell, R. H., eds., 

Stratigraphic nomenclature of the central Santa Monica 

Mountains, Los Angeles County, California: U. S. Geological Survey Bulletin 1457-E, p. E18-E22.

Vedder, J. G., 1973, Geologic framework and correlation of 

Miocene rocks in the Caliente Range: Society of Economic 

Paleontologists and Mineralogists, Pacific Section, Field 

Trip 2 Guidebook, p. 42-53. 

Vedder, J. G., 1975, Revised geologic map, structure sections, and 

well table, San Joaquin Hills—San Juan Capistrano area, 

California: U. S. Geological Survey Open-File Report 75-

552, 3 sheets, scale 1:24,000. 
25

Vedder, J. G., and Howell, D. G., 1976, Review of the distribution and tectonic implications of Miocene debris from the 

Catalina Schist, California Continental Borderland and 

adjacent coastal areas, in Howell, D. G., ed., Aspects of the 

California Continental Borderland: American Association 

of Petroleum Geologists, Pacific Section, Miscellaneous 

Publication 24, p. 326-340.

Vedder, J. C., Yerkes, R. F., and Schoellhamer, J. E., 1957, 

Geologic map of the San Joaquin Hills—San Juan Capistrano area, Orange County, California: U. S. Geological 

Survey Oil and Gas Investigations Map OM-193, scale 

1:24,000.

Weber, R. H., Jr., Cleveland, G. B., Kahle, J. E., Kiessling, E. 

F., Miller, R. V., Mills, M. F., and Morton, D. M., 1973, 

Geology and mineral resources study of southern Ventura 

County, California: California Division of Mines and Geology Preliminary Report 14, 102 p., map scale 1:48,000.

West, J. C., and Redin, T. W., 1991a, Correlation section across 

eastern Los Angeles basin from San Pedro Bay to San 

Gabriel Mts.: American Association of Petroleum Geologists, Pacific Section, scale 1:48,000 (horizontal), 1:12,000 

(vertical).

West, J. C., and Redin, T. W., 1991b, Correlation section across 

northern Los Angeles basin from Santa Monica Bay to 

Prado Flood Control Basin: American Association of 

Petroleum Geologists, Pacific Section, scale 1:48,000 

(horizontal), 1:12,000 (vertical).

Whistler, D. P., and Lander, E. B, 2003, New late Uintan to early 

Hemingfordian land mammal assemblages from the undifferentiated Sespe and Vaqueros formations, Orange County, 

and from the Sespe and equivalent marine formations in 

Los Angeles, Santa Barbara, and Ventura Counties, southern 

California, in Flynn, L. J., ed., Vertebrate fossils and their 

context—contributions in honor of Richard H. Tedford: 

Bulletin of the American Museum of Natural History, v. 

13, no. 279, p. 231-268.

Wilde, Melita, and Stock, Joann, 1997, Compression directions 

in southern California (from Santa Barbara to Los Angeles 

basin) obtained from borehole breakouts: Journal of Geophysical Research, v. 102, p. 4969-4983.

Woodford, A. O., and Bailey, T. L., 1928, Northwestern continuation of the San Onofre Breccia: University of California 

Publications, Bulletin of the Department of Geological 

Sciences, v. 17, no. 5, p. 187-191.

Woodford, A. O., and Gander, Craig, 1980, Early Tertiary conglomerates of the Santa Ana Mountains, California: Journal 

of Sedimentary Petrology, v. 50, p. 743-753.

Woodford, A. O., Schoellhamer, J. E., Vedder, J. G., and Yerkes, 

R. F., 1954, Geology of the Los Angeles basin, in Jahns, R. 

F., ed., Geology of Southern California: California Division 

of Mines Bulletin 170, Chapter 2, p. 65-81.

Woodford, A. O., Welday, E. E., and Merriam, R., 1968, Siliceous 

tuff clasts in the upper Paleogene of southern California: 

Geological Society of America Bulletin, v. 79, p. 1461-

1486.

Woodford, A. O., McCulloh, T. H., and Schoellhamer, J. E., 1972, 

Paleogeographic significance of metatuff boulders in middle 

Tertiary strata, Santa Ana Mountains, California: Geological Society of America Bulletin, v. 83, p. 3433-3436.

Wright, T. L., 1991, Structural geology and tectonic evolution 

of the Los Angeles basin, California, in Biddle, K. T., ed., 

Active margin basins: American Association of Petroleum 

Geologists Memoir 52, p. 35-134.

Wright, T. L., Parker, E. S., and Erickson, R. C., 1973, Stratigraphic evidence for timing and nature of late Cenozoic 

deformation in Los Angeles region, California [abs.]: 

American Association of Petroleum Geologists Bulletin, 

v. 57, p. 813.

Yeats, R. S., 1973, Newport-Inglewood fault zone, Los Angeles 

basin, California: American Association of Petroleum 

Geologists Bulletin, v. 57, p. 117-135.

Yeats, R. S., 1974, Newport-Inglewood fault zone, Los Angeles 

basin, California; reply: American Association of Petroleum Geologists Bulletin, v. 58, p. 884-888.

Yeats, R. S., 1976, Extension versus strike-slip origin of the 

Southern California Borderland, in Howell, D. G., ed., 

Aspects of the geologic history of the California Continental Borderland: American Association of Petroleum 

Geologists, Pacific Section, Miscellaneous Publication 

24, p. 455-485.

Yeats, R. L., 1983, Simi; a structural essay, in Squires, R. R., 

and Filewicz, M. V., eds., Cenozoic geology of the Simi 

Valley area, southern California: Society of Exploration 

Paleontologists and Mineralogists, Pacific Section, Fall 

Field Trip and Guidebook, p. 233-240.

Yeats, R. S., 1987, Late Cenozoic structure of the Santa Susana 

fault zone: U. S. Geological Survey Professional Paper 

1339, p. 137-160.

Yeats, R. S., and Beall, J. M., 1991, Stratigraphic controls of 

oil fields in the Los Angeles basin; a guide to migration history, in Biddle, K. T., ed., Active margin basins: 

American Association of Petroleum Geologists Memoir 

52, p. 221-237.

 Yerkes, R. F., 1957, Volcanic rocks of the El Modeno area, Orange 

County, California: U. S. Geological Survey Professional 

Paper 274-L, p. 313-334.

Yerkes, R. F., 1972, Geology and oil resources of the western 

Puente Hills area, southern California: U. S. Geological 

Survey Professional Paper 420-C, 63 p.

Yerkes, R. F., and Campbell, R. H., 1979, Stratigraphic nomenclature of the central Santa Monica Mountains, Los Angeles 

County, California: U. S. Geological Survey Bulletin 

1457-E, p. E1-E29.

Yerkes, R. F., and Campbell, R. H., 1980, Geologic map of eastcentral Santa Monica Mountains, Los Angeles County, 

California: U. S. Geological Survey Miscellaneous Investigations Series Map I-1146, scale 1: 24,000.

Yerkes, R. F., and Lee, W. H. K., 1979, Late Quaternary deformation in the Western Transverse Ranges: U. S. Geological 

Survey Circular 799-B, p. 27-37.

Yerkes, R. F., McCulloh, T. H., Schoellhamer, J. E., and Vedder, J. 

G., 1965, Geology of the Los Angeles basin—an introduction: U. S. Geological Survey Professional Paper 420-A, 

57 p.

References
26 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California Petroleum exploration drill holes that provide control on the total thickness of Vaqueros and Sespe Formations (differentiated and undifferentiated) 

APPENDIX 1 Map symbol Original operator, lease name & well number Section Township, Range (S. B. B. & M.) 1 Latitude (N.) Longitude (W.) (degrees) Elevation m (ft.) 2 Total depth m (ft.) Drill depths of stratigraphic boundaries, feet. 

1

Continental Oil Co. Anaheim No. 4-1

Sec. 5 

T.4 S., R.10 W.

33.8497 

117.9474

43 

(142) 

[kb]

3,255 

(10,679)

Sespe 8,680 to 9,220; overlain by

Topanga Fm.; rests on Eocene. 

2

Draucker, C. D. Draucker No. 1

Sec. 28 

T.3 S., R.7 W.

33.8847 

117.6160

179 

(586) 

[kb]

1,481 

(4,858)

Sespe 2,625 to 2,985; overlain by

Puente Fm.; rests on Santiago Fm.

3

Gill and Associates Forster No. 1

Sec. 13 

T.8 S., R.8 W.

33.4767 

117.6697

67 

(220) 

[?]

1,996 

(6,550)

Vaqueros and Sespe 4,000 to 5,050;

overlain by Topanga Fm.; rests on

Santiago Fm. 

4

Gill and Associates Krum No. 1

Sec. 7 

T.8 S., R.7 W.

33.4848 

117.6440

187 

(612) 

[kb]

2,169 

(7,117)

Vaqueros and Sespe 2,670 to 3,760;

overlain by Topanga (?); rests onSantiago Fm. 

5

Godfrey, A. L., Drill Co. Botiller No. 1

Sec. 29 

T.3 S., R.7 W.

33.8750 

117.6343

175 

(574) 

[rt]

1,455 

(4,775)

Sespe 0 to 1,840; top eroded; rests 

on Santiago Fm. 

6

Great Amer. Petrol. Co. Gapco No. B-1

Sec. 18 

T.2 S., R.8 W.

33.9968 

117.7522

268 

(880) 

[?]

958 

(3,142)

Sespe 2,600 to 3,142; may have reached granitic rock.

7

Humble Oil Co. O'Neill No. B-1

Sec. 25 

T.6 S., R.8 W.

33.6180 

117.6720

161 

(529) 

[kb]

1,581 

(5,187)

Vaqueros and Sespe 2,000? to 

3,470; overlain by Topanga (?); 

rests on Santiago Fm. 

8

Marcell, Douglas Puente Hills No. 1

Sec. 31 

T.2 S., R.8 W.

33.9525 

117.7503

434 

(1,425) 

[?]

958 

(3,142)

Sespe 5,158 to 5,800; overlain by

Topanga; rests on Eocene (?).

9

Morton and Sons El Toro No. 14-1

Sec. 14 

T.6 S., R.8 W.

33.6561 

117.6841

180 

(591) 

[?]

1,990 

(6,528)

Vaqueros and Sespe 1,150± to 

2,100±; overlain by Topanga (?) 

10

Morton and Sons Irvine No. 55-1

Block 55 

Irvine Ranch 

Survey

33.6193 

117.8759

58 

(190) 

[?]

2,873 

(9,427)

Sespe 6,530 to 8,550±; overlain by

Topanga and San Onofre Breccia 

Petroleum exploration drill holes that provide control on the total thickness of Vaqueros and Sespe Formations (difundifferentiated) or equivalents.

APPENDIX 1

Southeast sector, figure 3
27

11

Patton Oil Co. Three Corners No. 1

Sec. 21 

T.2 S., R.8 W.

33.9838 

117.7314

216 

(710) 

[?]

960 

(3,151)

Sespe 2,430 to 3,000±; overlain by Topanga; rests on granite.

12

Pomona Oil Co. No. 1

Sec.19 

T.2 S., R.8 W.

33.9841 

117.7632

335 

(1,100) 

[?]

1,576 

(5,169)

Sespe 4,140 to 5,169; overlain by Topanga; rests on granite?

13

Rubicon Oil Co. Wilcox No. 1

Sec. 6 

T.4 S., R.8 W.

33.8563 

117.7623

137 

(450) 

[df]

1,928 

(6,325)

Sespe 4,330 to 5,780; overlain by Topanga; rests on Santiago Fm.

14

Santa Fe Minerals Co. (or Casex Co.) Government No. 165-1

Sec. 17 

T.3 S., R.7 W.

33.9072 

117.6356

152 

(498) 

[kb]

1,826 

(5,991)

Sespe (?) 2,620 to 2,950; overlain 

by Topanga (?) or lower Mohnian (?); rests on Eocene.

15

Shell Oil Co. Irvine One No. 44-166

Sec. 11 

T.7 S., R.9 W.

33.5743 

117.7939

269 

(884) 

[df]

2,995 

(9,826)

Vaqueros 395 to 3,075; Sespe 3,075 

to 5,700±; Topanga above Vaqueros; Santiago Fm. below Sespe. 

16

Shell Oil Co. Puente Corehole No. 4

Sec. 18 

T.2 S., R.8 W.

33.9930 

117.7541

269 

(884) 

[gr]

930 

(3,052)

Sespe 2,300 to 2,934; overlain by Topanga; rests on granite.

17

Shell Oil Co. Irvine Corehole No. 8

Block 102 

Irvine Ranch 

Survey

33.6769 

117.7918

34 

(110) 

[?]

1,437 

(4,715)

Vaqueros 470 to 1,700; Sespe 1,700 

to 2,550; overlain by alluvium; rests on Santiago Fm. 

18

Shoreline Oil Co. Pinkerton No. 1

Sec. 5 

T.5 S., R.9 W.

33.7668 

117.8402 

50 

(165) 

[df]

1,105 

(3,625)

"Vaqueros and Sespe 1,816± to 2,500±"; overlain by U. Pliocene; 

rests on Eocene.

19

Standard Oil Co. of Calif. Murphy Coyote No. 373

Sec. 18 

T.3 S., R.10 W.

33.9078 

117.9738

116 

(380) 

[df]

3,994 

(13,104)

Sespe 9,535 to 10,690; overlain by Topanga; rests on Eocene.

20

Stella, E. F., Trustee Kraemer-Backs No. 2

Sec. 33 

T.2 S., R.8 W.

33.9555 

117.7298

291 

(955) 

[?]

1,594 

(5,231)

Sespe 3,835 to 4,400; overlain by Topanga; rests on Eocene.

21

The Texas Co. Buena Park Community No. A-13-1

Sec. 8 

T.4 S., R.10 W.

33.8431 

117.9527

41 

(133) 

[kb]

2,736 

(8,977)

Sespe 8,080 to 8,450; overlain by Topanga; rests on Eocene. 

22

The Texas Co. O'Neill Estate (NCT-1) No. 1

Sec. 22 

T.8 S., R.7 W.

33.4637 

117.5909

120 

(394) 

[kb]

2,147 

(7,044)

Sespe 1,020 to 2,520; overlain by 

San Onofre Breccia; rests on Eocene. 

23

Tidewater Assoc. Oil Co. Abacherli No. 1

Sec. 12 

T.3 S., R.8 W.

33.9203 

117.6730

354 

(1,160) 

[df]

1,517 

(4,977)

Sespe 3,820 to 4,210; overlain by Topanga; rests on Eocene.

Appendix
28 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California APPENDIX 1—Continued 22 The Texas Co. O'Neill Estate (NCT-1) No. 1 Sec. 22 T.8 S., R.7 W. 33.4637 117.5909 120 (394) [kb] 2,147 (7,044) Sespe 1

San Ono

23 Tidewater Assoc. Oil Co. Abacherli No. 1 Sec. 12 T.3 S., R.8 W. 33.9203 117.6730 354 (1,160) [df] 1,517 (4,977) Sespe 3

Topanga

24 Atlantic Oil Co. Nettleship No. 1 Sec. 30 T.1 N., R.16 W. 34.1339 118.5918 335 (1,100) [kb] 1,096 (3,595) 2,700-3

25 Havenstrite Oil Co Tapo No. 1 Sec. 13 T.3 N., R.18 W. 34.3461 118.7131 591 (1,938) [kb] 2,559 (8,394) Las Llaja26 Occidental Petrol. Corp. USL No. 83X-2 Sec. 2 T.3 N., R.19 W. 34.3735 118.8333 423 (1,388) [kb] 2,591 (8,500) Eroded V

unconfotransitioFm. at a

27 Standard Oil Co. of Calif. Austin No. 1 Sec. 11 T.1 S., R.17 W. 34.1019 118.6344 384? (1,260?) [?] 763 (2,503) Sespe fr

1,250; r

28 The Superior Oil Co. Broome Ranch No. 1 Sec. 13 T.1 S., R.21 W. 34.0853 119.0384 13 (44) [kb] 1,156 (3,792) Vaquero

Fm. rest

29

Union Oil Co. of California Torrey No. 92

Sec. 5 

T.3 N., R.18 W.

34.3733 

118.7845

572 

(1,877) 

[rt]

4,569 

(14,989)

By correVaquerothicknes10,285±Fm. ben

30

Western Gulf Oil Co. Hunter No. 3

Sec. 6 

T.3 N., R.18 W.

34.3735 

118.8088

545 

(1,789) 

[kb]

2,900 

(9,514)

Eroded VunconfotransitioFm. at a

31

Western Gulf Oil Co. Salisbury No. 2

Sec. 19 

T.1 S., R.19 W.

34.0673 

118.9133

472 

(1,550) 

[kb]

1,781 

(5,843)

"Lower surface; underlai5,280. 

32

Morgan-Brown U-6 No. 1

Sec. 20 

T.1 S., R.14 W.

34.0734 

118.3761

51 

(167) 

[kb]

3,094 

(10,152)

"Sespe" 

by Topa"granite

2 Depth datum: kb, rt, df, gr = kelly bushing, rotary table, derrick floor, ground level, respectively.1 San Bernardino Base and Meridian

Northwest sector, figure 4

Palinspastic reconstruction, figure 7
29 Appendix

30

Western Gulf Oil Co. Hunter No. 3

Sec. 6 

T.3 N., R.18 W.

34.3735 

118.8088

(1,789) 

[kb]

2,900 

(9,514)

transition to marine Eocene Las Llajas Fm. at about 8,550. 

31

Western Gulf Oil Co. Salisbury No. 2

Sec. 19 

T.1 S., R.19 W.

34.0673 

118.9133

472 

(1,550) 

[kb]

1,781 

(5,843)

"Lower Topanga Fm." (=Vaqueros) at surface; rests on Sespe at 2,760; Sespe underlain by Eocene at 

5,280. 

32

Morgan-Brown U-6 No. 1

Sec. 20 

T.1 S., R.14 W.

34.0734 

118.3761

51 

(167) 

[kb]

3,094 

(10,152)

"Sespe" 9,415 to 10,152; overlain 

by Topanga volcanic rock; rests on "granite".

2 Depth datum: kb, rt, df, gr = kelly bushing, rotary table, derrick floor, ground level, respectively.1 San Bernardino Base and Meridian

Palinspastic reconstruction, figure 7
30 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California APPENDIX 2 Petroleum exploration drill holes deep enough to indicate the presence of Vaqueros and/or Sespe Formations (differentiated and undifferentiated) 

thickness control Map symbol Original operator, lease name & well number Section Township, Range (S. B. B. & M.) 1 Latitude (N.) Longitude (W.) (degrees) Elevation m (ft.) 2 Total depth (T.D.) m (ft.) Drill depths of stratigraphic boundaries, feet. 

33 Bartholomae Oil Corp. Stern No. 12 Sec. 22 T.3 S., R.10 

W

33.8981 

117.9117

(310) 

[kb]

2,897 

(9,506)

Sespe 8,846 to T.D.; overlain by

Topanga.

34

Aeco Corp. Nohl-Bixby No. 1

Sec. 12 

T.4 S., R.9 W.

33.8426 

117.7670

(526) 

[kb]

930 

(3,050)

Sespe 2,640 to T.D.; overlain 

by Topanga.

35

Amerada Anaheim Comm. No. 48

Sec. 8 

T.4 S., R.10 W.

33.8333 

117.9502

(132) 

[kb]

2,727 

(8,946)

Sespe 8,860 to T.D.; overlain 

by Topanga. 

36

Carrey, A. A. Bixby-Nohl No. 1

Sec. 9 

T.4 S., R.9 W.

33.8360 

117.8280

(337) 

[kb]

1,145 

(3,758)

Sespe 3,100 to T.D.; overlain 

by Topanga.

37

Chevron USA Inc. Murphy-Whittier No. 304

Sec. 26 

T.2 S., R.11 W.

33.9741 

117.9988

(846) 

[df]

4,332 

(14,213)

Sespe 13,885 (true vertical depth to

T.D.); overlain by Topanga. 

38

Continental Oil Co. Turnbull Community No. 3

Sec. 13 

T.2 S., R.11 W.

33.9982 

117.9793

(576) 

[rt]

1,709 

(5,608) "Sespe?" 5,500 to T.D.

39

McKee Oil Co. Kokx Community No. 8-1

Sec. 16 

T.4 S., R.9 W.

33.8235 

117.8300

(290) 

[df]

1,221 

(4,005)

Vaqueros and Sespe Formation,

undifferentiated 3,595 to T.D.

40

Morton and Sons. Irvine No. 56-1

Sec. 24 

T.6 S., R.10 W. 

(projected)

33.6375 

117.8717

(215) 

[?]

2,064 

(6,770)

Vaqueros 5,250± to 6,450±; 

Sespe 6,450± to T.D.; Vaqueros overlai

by Topanga. 

41

Orange Comm. Oil Assoc. Forker No. 1

Sec. 29 

T.4 S., R.9 W.

33.8001 

117.8424

(226) 

[df]

1,392 

(4,568)

Vaqueros and Sespe, undifferentiated 3,600 to T.D.?

42

Red Star Oil Co. Ward Associates No. 1

Sec. 29 

T.5 S., R.9 W. 

(projected)

33.7156 

117.8430

(76) 

[kb]

1,598 

(5,243)

Vaqueros and Sespe Formation,

undifferentiated 4,464 to T.D.; 

overlain by Topanga.

Southeast sector, figure 3

94 

160 

40 

103 

258 

160

88

66

69

23
31 Appendix

43

Richfield Oil Corp. Edwards No. 1

Sec. 15 

T.3 S., R.10 W.

33.9054 

117.9195 

(322) 

[kb]

2,923 

(9,591)

Sespe 9,546 to T.D.; overlain 

by "Topanga (?)". 

44

Shell Oil Co. Harbeson No. 1

Sec. 9 

T.4 S., R.10 W.

33.8367 

117.9353

(141) 

[df]

2,624 

(8,608)

"Vaqueros" (?) 8,255 to T.D.; 

overlain by Topanga.

45

Shell Oil Co. Irvine Four No. 51-130 original hole (OH) & redrill (RD)

Sec. 5 

T.7 S., R.9 W.

33.5959 

117.8485

(381) 

[gr]

1,960 

(6,431) OH 

2,756 

(9,043) RD 

Original hole: Sespe 5,950± to T.D; overlain by Topanga. Redrill: Sespe 7,100 to 7,630; underlain by Santiago Formation(?); intrusive diabase above. 

46

Shell Oil Co. Moulton No. 88-4

Sec. 4 

T.7 S., R.8 W.

33.5856 

117.7118

(248) 

[df]

1,209 

(3,967)

Vaqueros 1,920± to 2,670±; 

Sespe 2,670± to T.D. 

47

Standard Oil Co. of Calif. Emery No. 87

Sec. 13 

T.3 S., R.11 W.

33.9047 

117.9807

(196) 

[df]

3,359 

(11,020)

Sespe 10,075 to T.D.; overlain 

by volcanic rocks. 

48

Standard Oil Co. of Calif. Emery No. 92

Sec. 13 

T.3 S., R.11 W.

33.9034 

117.9768

(433) 

[df]

3,672 

(12,048)

Sespe 10,800 to T.D.; faulted 

against Topanga at 10,800. 

49

Standard Oil Co. of Calif. Kellogg No. 1

Sec. 20 

T.4 S., R.10 W.

33.8158 

117.9546

(112) 

[df]

3,118 

(10,229)

Vaqueros interbedded with Sespe 

9,930 to T.D.

50

Standard Oil Co. of Calif. Pacific Community No. 1

Sec. 26 

T.3 S., R.11 W.

33.8754 

118.0053

(80) 

[df]

3,551 

(11,651) Sespe 11,375 to T.D. 

51

Standard Oil Co. of Calif. Woodward Comm. No. K-1

Sec. 11 

T.3 S., R.11 W.

33.9223 

118.0011

(245) 

[df]

3,714 

(12,184) Sespe 11,965 to T.D. 

52

The Texas Co. Ragan (NCT-1) No. 1

Sec. 15 

T.4 S., R.9 W.

33.8186 

117.8047

(392) 

[kb]

1,734 

(5,690)

"Vaqueros and Sespe Formations, undifferentiated, 3,605-4,650±";

overlain by Topanga; faulted (?).

53

The Texas Co. Ruff No. 1

Sec. 1 

T.3 S., R.10 W.

33.8505 

117.8712

(204) 

[kb]

2,590 

(8,497)

Sespe 8,057 to T.D.; overlain by

Topanga.

54

Union Oil Co. of California Chapman No. 29

Sec. 29 

T.3 S., R.9 W.

33.8776 

117.8449

(293) 

[kb]

3,199 

(10,496)

"Vaqueros and Sespe Formations, undifferentiated, 9,128-T.D."; 

overlain by Topanga.

55

Union Oil Co. of California Olive Community No. 4-1

Sec. 8 

T.4 S., R.9 W.

33.8324 

117.8510

(209) 

[df]

1,291 

(4,236)

Vaqueros interbedded with Sespe 

4,160 to T.D.; "Norwalk fault" at

4,160±.

56

Union Oil Co. of California O'Neill No. 1

Sec. 30 

T.7 S., R.7 W.

33.5358 

117.6432

(372) 

[?]

1,378 

(4,520)

Vaqueros-Sespe 2,950± to T.D.; overlain

by Topanga. 

57

Western Gulf Oil Co. Diamond Bar No. 1

Sec. 28 

T.2 S., R.9 W.

33.9698 

117.8311

(1,102) 

[?]

2,081 

(6,828)

Sespe 5,700± to T.D.; overlain by Topanga.

98 

43 

116 

76 

60 

132 

34 

24 

75 

119 

62 

89 

64 

113 

336 
32 Mid-Tertiary Isopach and Lithofacies Maps for the Los Angeles Region, California APPENDIX 2—Continued APPENDIX 3 Map symbol Lease name & well number Section Township, Range (S. B. B. & M.)1 Latitude (N.) Longitude (W.) (degrees) Elevation m (ft) 2 Total depth m (ft) Drill depths of stratigraphic boundaries, feet 

59 Shell Oil Co. Schonfeld No. 1 Sec. 30 T.2 N., R.16 W. 34.2286 118.6040 283 (928) [df] 1,573 (5,162) "Topanga Fm." rests on Eocene at abo

2,000. 

60

Union Oil Co. of California Union-Signal-Texam U-19 No. 1

Sec. 35 

T.1 S., R.14 W.

34.0424 

118.3097

62 

(203) 

[gr]

1,678 

(5,506)

"Albite and oligoclase-epidote amphibolites" (Sorensen, 1985, 

p. 999) overlain unconformably by Mohnian of Modelo Fm.

1 San Bernardino Base and Meridian2 Depth datum: df, gr = derrick floor, ground level, respectively.

Northwest sector, figure 

4

Palinspastic reconstruction, figure 7

Petroleum exploration drill holes that provide critical insights about the regional extent and history of Vaqueros and/or Sespe strata without encounte

57

Western Gulf Oil Co. Diamond Bar No. 1

Sec. 28 

T.2 S., R.9 W.

33.9698 

117.8311

(1,102) 

[?]

2,081 

(6,828)

Sespe 5,700± to T.D.; overlain 

by Topanga.

58

Bell, J. A., Operator Tapo No. 71X orig. holeand deepening

Sec. 14 

T.3 N., R.18 W.

34.3504 

118.7288

(2,139) 

[kb]

2,252 

(7,389)

Sespe, 3,255 to TD; overlain

unconformably by Calabasas Fm. (Luisian).

1 San Bernardino Base and Meridian2 Depth datum: kb, rt, df, gr = kelly bushing, rotary table, derrick floor, ground level, respectively.

Northwest sector, figure 4

652