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MID-TERTIARY CONGLOMERATES AND THEIR BEARING ON TRANSVERSE RANGE TECTONICS, SOUTHERN CALIFORNIA

By Robert G. Bohannon, U.S. Geological Survey, Denver, Colo. 80225

ABSTRACT rocks studied are shown in figure 2. Basalt dated in the Plush Ranch Formation coarse redbeds characterize mid-Tertiary yields ages of 17.4a3.7 and 19.6al.1 m.y. continental sedimentary rocks in southern (million years ), in the Vasquez Formation California. They include the Simmler, 23.9aO.8 and 24.9f2.1 m.y., and in the Sespe, Plush Ranch, and Vasquez Formations, formation of Diligencia 22.4a2.9 m. y. and the formation of Diligencia, which are (Crowell, 1973 ). Although the dated rocks probably in part contemporaneous. These are not precisely the same age, the sed- units contain locally derived conglomerates imentary sections containing these dated that accumulated in several fault-bounded rocks possibly overlap in age and appear basins. These east-west trending basins to be part of a unique tectonic and sed- and associated uplift areas apparently imentary phase which may have developed crossed the present trace of the San in different places through time. Andreas and San Gabriel faults and were later offset by them. BAS IN DESCRIPTIONS

INTRODUCTION Simmler Formation

Mid-Tertiary continental rocks in the The Simmler Formation in the La Panza Transverse Ranges are characterized by Range ( fig. 1, no. 1 ) consists of coarse coarse redbeds, which mark an interruption conglomerate and minor arkose. Angular in the extensive marine deposition that clasts of arkose and rounded clasts of prevailed in much of southern California medium-grained biotite quartz monzonite, duridg the Tertiary Period. This phase of granodiorite and devitrified porphyritic tectonics and sedimentation occurred about felsites are the predominant clasts. the same time as, or just prior to, the in- Pebble imbrication suggests transport ception of Tertiary volcanism in southern from southwest to northeast. California and triple junction migration A thick section of Simmler occurs along the coast (Atwater, 1970 ), and just immediately northeast of the Nacimiento prior to the inferred initiation of strike- (Rinconada) fault; however, none occurs slip faulting on the San Andreas system. on its southwest side. This distribution In order to understand the tectonic and the paleocurrent indicators suggest framework and sedimentologic history of that the Simmler Formation was derived off basins in existence at that time, the an active scarp at or near the Nacimiento Simmler, Sespe, Plush Ranch, and Vasquez fault (Vedder and Brown, 1968 ); however, Formations,·and the formation of Diligencia clasts in the Simmler indicate a conglom- were studied in 10 localities ( fig. 1 ). eratic provenance. According to T. W. Special attention was given the conglom- Dibblee ( personal commun., 1974 ), nearby erate facies and their clast types, prov- rocks across the fault are nearly all enance, and paleocurrent features. Con- sandstone and shale, not conglomerate. glomerate analysis helped document basin This problem could be alleviated by assum- history and development; using this infor- ing that conglomerate once existed in the mation, individual basins were compared proposed source but was now eroded, or stratigraphically and chronologically. that strike slip occurred on the Nacimiento fault during or after AGE RELATIONS deposition of the Simmler Formation. In the northern Cuyama badlands (fig. Age control comes from fauna in under- 1, no. 3 ), coarse conglomerate of the lying and overlying strata and from po- Simmler Formation contains clasts of tassium-argon age determinations taken on medium-grained muscovite-biotite quartz basalt flows in three of the areas. The monzonite, banded muscovite-biotite general age relations of the mid-Tertiary gneiss, rare aegerine-hornblende-

75 CALIFORNIA DIVISION OF MINES AND GEOLOGY

e 1 La Panza Range 6 Canton Canyon 9 Abel Mountain \)J 2 Caliente Range 7 Charlie Canyon + and r, fB 3 Cuyama Badlonds 8 Texos Conyon 14,4 1 Mount Pinos area 078» 4 Lockwood Valley 9 Vasquez Rocks 5 Upper Sespe Creek 10 Orocopia Mountains 0 BLUE 2 MountainFrazier *'6 ROCKFAULT--..3 &40 4

Figute 1.--Index map showing the location of the 10 study areas in southein California. muscovite granite and, at a few localities, that supplied detritus to the Simmler dacite, oxyhornblende welded tuff, and Formation. The silicic volcanic clast flow-banded rhyolite. Most of the section suite may have been derived from the east has paleocurrent indicators that indicate across the San Andreas fault. south to north transport; however, the few In the eastern Caliente Range (fig. 1, localities that contain abundant silicic no. 2 ), the Simmler Formation consists of volcanic clasts have pebble imbrication arkose and siltstone with only minor Suggestive of east to west and southeast conglomerate like that in the Cuyama to northwest transport. This transport badlands. Current lineations on sand- data, and the fact that the Simmler fines stone beds are consistent with south to to the northwest suggest that its principal north and southeast to northwest current source was to the south or southeast. An flow. exposure of banded biotite gneiss, biotite granodiorite, and quartz monzonite occurs Sespe Formation under the Caliente Formation just to the south across the Blue Rock fault, south of On upper Sespe Creek (fig. 1, no. 5 ), which the Simmler Formation, underlying conglomerates of the Sespe Formation have Pattiway Formation, and overlying Vaqueros clasts of coarse-grained arkose, medium- Formation are missing. This area could grained muscovite-biotite quartz monzon- have been a highland of basement rocks ite, a variety of recrystallized dacites 76 CALIFORNIA DIVISION OF MINES AND GEOLOGY

YEARS NORTH PACIFIC LOCALITY MW (X106) AMERICAN COAST ij LAND FORAMAGE U) MAMMALAGE 2 3 4 5 6 7 8 9 I0 CLARENDONIAN Mohnion Monterey t-.--*-.-Modelo Fm C. Luisian Monterey Formaton Caliente Formation Formaton •_ M nt Canyon Format on U BARSTOVIAN -EBIann I HEMINGFORDIAN Saucesian Plush1/ R ncon Shole UN 1Tick ConyonU Formation Formation Voqueros Formation Ranch of ARIKAREEAN Zemorrian Formation Vaqueros Format on Vasquez Formation Diligencia WHITNEYAN j O03: -30 ORELLAN Refugian Smmler Format on Sespe Formation CHADRONIAN .= 10 DUCHESNEAN Narizlon ColdwaterCozy Dell Ss:Sh UINTAN ·· ··· ' 11110WW i Ulatizion Sandstone 1 11 1.I036ra036Formation 3 BRIDGERIAN Juncal UN n -50 Penution UN Formation WASATCHIAN -:IC Son m CLARKFORKIAN Bulitian UN Francisquito / TIFFANIAN Ynezion Pottiwoy Formation i' :: ·· Formation :: :: : 2f -60- TORREJONIAN m PUERCAN Danian U.K. -70- 1 .:1:r--uN--1. :: I..... 9 Of Carmon,(1964). 2/ Of Johns,(1940). 2/ Of Crowell and Susuki,(1959). Figure 2.---Correlation chart showing the relative ages of studied sections and age ranges of dated basalt samples. Line pattern in series column indicates zone of controversy of series boundaries; stippled pattern indicates nondeposition or erosion. UN, unnamed rocks. and rhyodacites, rare anorthosite (plagio- amphibolite, banded augite-biotite clase AN25 ), and mafic volcanics. Pebble gneiss, biotite-hornblende syenite, imbrication shows clast transport from the pyroxene gabbro, quartz syenite, norite, north across the Big Pine and Pine Mountain and unmistakable 220-m.y.-old Lowe faults. It is possible that the crystal- Granodiorite of Miller, 1946 (a biotite line clasts were derived from the highland monzonite, syenite, and granodiorite in the Cuyama badlands area, and the that is commonly sheared and contains arkose from Eocene sandstone exposures to garnet and large potassium feldspar the north; however, neither area is known phenocrysts ). Pebble imbrication data to contain anorthosite or mafic volcanics. Suggest west to east transport from It is also possible that the Nacimiento across the San Gabriel fault. Outcrops (Rinconada) and Pine Mountain faults were of anorthosite and related rocks occur at one time continuous and that right in the western San Gabriel Mountains to strike-slip occurred on them (T. W. Dibblee, the east; however, the large size of personal commun., 1974). If so, the clasts (up to 7 m) indicates a high Sespe would have been deposited southeast relief source close by. Right slip of of the present outcrop area and could about 60 km is required on the San have received detritus from the Alamo Gabriel fault to juxtapose the Sespe in Mountain area or from across the San Canton Canyon to the anorthosite-Lowe Gabriel fault. Granodiorite source in the San Gabriel In Canton Canyon the Sespe Formation Mountains (Crowell, 1954). (fig. 1, no. 6 ) is coarse conglomerate, breccia, and immature sandstone with clasts of anorthosite (plagioclase AN 45-50), 77 CALIFORNIA DIVISION OF MINES AND GEOLOGY

plush Ranch Formation of Carman (1964) nearby and had considerable relief; however, Frazier Mountain is about 12-14 In Lockwood Valley ( fig. 1, no. 4 ), the km southeast, across the Big Pine fault, Plush Ranch Formation of Carman (1964) which suggests possible strike slip on j contains three conglomeratic members. that fault. Hill and Dibblee ( 1953), One, at the base of the formation (member 1 Poynor ( 1960), and Crowell (1968) presented } of Carman, 1964 ), has clasts of medium- additional data to support the claim for i grained biotite quartz monzonite, banded 14 km of left slip on the Big Pine fault, 1 pyroxene-biotite gneiss, coarse- to medium- and Crowell (1968) suggested that it had I grained syenite, and rare biotite-rich a two-stage displacement history that augen and porphyroblastic gneiss like that involved dip slip in the mid-Tertiary gneiss cropping out on Frazier Mountain to and later strike slip in the Quaternary. 4 the southeast of locality 4. Pebble imbrication data in this conglomerate unit Vasquez Formation i are ambiguous, with transport both from , the northwest and from due south. Over- In the Soledad basin the Vasquez For- lying this lower conglomerate is a sequence mation occurs in three separate outcrop i of interbedded arkose and siltstone (mem- areas--Charlie Canyon ( fig. 1, no. 7 ), bers 2 and 3 of Carman, 1964 ) that con- Texas Canyon (no. 8 ), and Vasquez Rocks ; tains, near its top, large coarse lenses ( no. 9 ). of monolithologic breccia with clasts of The Charlie Canyon section is mostly coarse-grained biotite granite identical sandstone and siltstone at its base, but with the Jurassic(?) Mount Pinos Granite coarsens upward and is conglomeratic of Carman (1964) exposed a few kilometres about mid-section. This conglomerate 1 to the north. Near the top of the Plush and associated shale chip breccias occur : Ranch Formation, conglomerate and breccia in beds and lenses at the top of a sand- : of member 5 (Carman, 1964 ) occur in a thick stone unit and contain (2-10 cm ) clasts ' and long, but narrow, unit along the Big predominantly of coarse- to medium- 1 Pine fault. The large clasts within the grained arkose, medium-grained muscovite- unit include biotite-rich augen, porphyro- biotite quartz monzonite, and hornblende- blastic gneiss, and medium-grained biotite quartz diorite, and some banded biotite quartz monzonite. Pebble imbrica• garnet-biotite gneiss. Higher in the tion data (Kahle, 1966; this report ) show section, conglomerate is the predominant transport from south to north. lithology; quartz diorite clasts increase The lower conglomerate of the Plush in percentage to the top of the section, Ranch possibly had different sources. where there is a coarse monolithologic Clast lithologies such as augen gneiss and breccia of them with clasts as large as syenite relate to southerly source areas 5 m. Paleocurrent features are scarce on Frazier Mountain and possibly to the in the lower, finer grained units in the Soledad basin, while granitic gneiss and Charlie Canyon section but are excellent quartz monzonite are like rocks found in the higher and coarser units. Pebble several km to the north on Mount Pinos. imbrication data show transport from due The breccia lenses must have been derived east to west about mid-section, with a from the area of Mount Pinos, because uniform shift to transport from nearly their coarse, poorly sorted, massive south to north at the top of the section. texture suggests that they originated as The paleocurrent data in the Charlie landslides off a high, nearby source and Canyon Vasquez Formation suggest an their clast lithology is identical to that easterly to southerly source area and of the Mount Pinos Granite. The breccia the large size of many clasts indicates along the Big Pine fault has clasts that that it was nearby; however, the only suggest a source in the augen-gneiss exposures for some distance east and terrain of Frazier Mountain. Their mass- southeast, across the San Francisquito ive, poorly sorted character and coarse fault ( fig. 3 ), are of the Cretaceous clasts indicate that the source was Pelona Schist, a distinctive greenschist

78 CALIFORNIA DIVISION OF MINES AND GEOLOGY

that does not occur as clasts in the probably originated in that area. Charlie Canyon section. Konigsberg (1967) If so, the alluvial fan represented by proposed that granitic, high-grade meta- this detritus must have spread across morphic and sedimentary rocks tectonically deposits of the Vasquez Formation at capped the Pelona Schist, but were eroded Vasquez Rocks; hence, the Texas Canyon off as the Sierra Pelona anticline ( fig. 3 ) and Vasquez Rocks basins must have been rose, leaving a core of Pelona Schist ex- joined at that time. It is not clear where posed. Tectonic capping of the Pelona the source for the basalt clasts in the Schist can be demonstrated on the southeast lower part of the section was, however, side of Sierra Pelona Ridge, where green- as there are no known occurrences of schist is overlain by granitic rocks on a similar basalt in the area. The basalt zone of mylonite. · in the·Vasquez Rocks area does not have The Vasquez Formation in Texas Canyon the extensive calcite alteration nor the is predominantly conglomerate, which dense plagioclase lath concentration of Remenyi (1966) subdivided on the basis of these clasts, and thus does not offer a clast type and matrix color. The Pelona likely source. It is possible the clasts and Vasquez Canyon faults bound the north- were derived from northeast across the west and southeast sides of the Texas San Andreas fault. Canyon basin, respectively, and both faults The Vasquez Formation at Vasquez Rocks flank locally derived breccias. On the has two distinct conglomerate clast suites. northwest side the formation contains One at the base and top of the section breccia of foliated medium-grained quartz contains clasts of coarse-grained anortho- monzonite, and on the southeast side, a site, biotite-hornblende gabbro, medium- coarse biotite-rich augen-gneiss breccia, grained syenite, and banded biotite gneiss. both of which are faulted against basement In the middle of the section a unit of rock types similar to their clasts. Con- crossbedded sandstone and breccia lenses glomerate in the central part of the basin, contains large clasts of epidote-rich low in the section, has clasts of pilo- Lowe Granodiorite and basalt similar to taxitic basalt ( plagioclase, An60 ) with the Vasquez basalts. extensive alteration to calcite, banded Pebble imbrication in the upper con- garnet-muscovite-biotite gneiss, and glomerate indicates transport from the flow-banded rhyolite. This conglomerate south, across the Soledad fault ( fig. 3 ), contains fragments of coarse-grained and the anorthosite terrain there matches biotite granite but none of basalt near the clast lithology. These data suggest the top of the section. There is also a that the Soledad fault was active as a conglomerate unit at the top of the dip-slip fault during Vasquez deposition. section on the east side of the basin Paleocurrent data are absent in the that contains clasts of coarse-grained granodiorite-bearing breccias (Lowe); anorthosite, diorite, gabbro, Lowe Grano- however, the unique lithology of the Lowe diorite, syenite, augen gneiss, and makes it easily relatable to a source. altered red andesite. Nearby outcrops of epidote-rich Lowe occur Although paleocurrent indicators are due east and northeast of the breccias. rare in the Texas Canyon rocks, the Vasquez basalts, which are stratigraph- derivation of many of the units is obvious. ically lower than the Lowe-bearing Clasts in the breccias that flank the breccias, occur in this source area in basin match adjacent basement rock lithol- patches. This area, then, probably pro- ogies and were probably locally derived vided the source for these breccias. off dip-slip fault scarps of the Pelona Very little, if any, of the Vasquez Rocks and Vasquez Canyon faults ( fig. 3 ). The section appears to have been derived from anorthosite conglomerate bears clast the west, as arkose, siltstone, and lithologies like basement rocks of the borates are faulted against gneiss there western San Gabriel Mountains and of the and conglomerates in that area bear Vasquez Formation volcanic sequence near anorthosite clasts from the southeast. the western San Gabriels, and thus

79 1 I .,

CALIFORNIA DIVISION OF MINES AND GEOLOGY

Formation of Diligencia PALINSPASTIC RECONSTRUCTION

Several conglomeratic units occur in the Crowell ( 1962, 1968 ), Ehlig and Ehlert formation of Diligencia in the Orocopia ( 1972), Carman ( 1964), Poynor ( 1960), Mountains ( fig. 1, no. 10 ). Lenticular Kahle ( 1966), and Sage (1973) have out- conglomerate beds at the base of the lined evidence suggesting that 210 km section contain pebbles and cobbles of right slip has occurred on the San Andreas banded muscovite-biotite gneiss, of fault, 60 km right slip on the San Gabriel medium-grained biotite quartz monzonite, fault, and 14 km left slip on the Big Pine and of granodiorite. Higher in the section, fault since the Miocene. By making palin- interbedded with a lakebed sequence of spastic adjustments to account for these arkose, siltstone, limestone, and borates, amounts of slip, a diagram such as figure there are a few massive beds of poorly 3 can be constructed. Figure 3 shows a sorted conglomerate with pebbles and small proposed distribution of basins that re- cobbles of anorthosite, gabbro, and ceived sediment in the mid-Tertiary. This : possible Lowe Granodiorite. In the upper diagram can be constructed because the part of the section, exposed in the west- total documented slip on the faults in- ern part of the formation, a coarse con- volved appears to have taken place after I glomerate contains clasts of medium- deposition in the basins involved. Also, grained syenite, pilotaxitic basalt of the I believe that the resultant basement rock · same lithology and texture as the basalt and source area distribution fits best clasts found in the Vasquez Formation in with observed sedimentologic data gathered Texas Canyon, and less commonly augen in this study. gneiss. Coarse unsorted breccia lenses Faults thought to have been active in a 5 having clasts of coarse-grained biotite normal sense during the mid-Tertiary are granite occur interstratified with this shown as hachured lines, present-day out- 5 conglomerate. crops of mid-Tertiary rocks are shown in Basement rock exposures north and east a lined pattern, and other areas thought { of the Orocopia Mountains consist of to have received continental sediment quartz monzonite, granodiorite, and are shown stippled on figure 3. With this • gneiss that probably provided the source configuration, the Pelona Schist exposures 4 for the conglomerate at the base of the on Abel Mountain and Sierra Pelona Ridge, • formation of Diligencia. Just south of and the exposures of the Precambrian the Diligencia exposures, across the Orocopia Schist of Miller (1944) in the 1 Clemens Well fault ( fig. 1 ), outcrops of Orocopia Mountains, as well as the corres- 1 anorthosite, gabbro, and syenite could ponding Sierra Pelona and Orocopia anti- ! have provided the detritus to the thin, clines, appear to line up as one major • but massive conglomerate beds interstrat- east-west trending feature. This ified with the lakebed sequence. The structure, which must have been forming 1 granite breccias in the upper part of th6 in the mid-Tertiary but had not yet ex- section probably had their source immed- posed schist, is flanked on the north and I iately to the north where granite crops northeast by the Blue Rock-San out today. The large basalt clasts, how- Francisquito faults, and the Simmler, • ever, are unlike any rocks presently Charlie Canyon, and Diligencia basins. exposed in the nearby area. They are The Simmler and Charlie Canyon sections • coarsest in the west and fine to the east are very similar, suggesting that they j and southeast, which suggests a westerly were deposited in an interconnected • source that could possibly be either basin. eroded or buried under elastic sediments On the south, the Sierra Pelona- 1 in the Mecca Hills ( fig. 1 ). Using the Orocopia anticlines are flanked by complex following palinspastic reconstruction, faults and basins, which include the Big the Mecca Hills area could also provide Pine and Soledad faults, and the Lockwood the source for the similar basalt clasts Valley, Texas Canyon, and Vasquez Rocks in the Texas Canyon area. basins. Granite, which occurs in outcrop

80 CALIFORNIA DIVISION OF MINES AND GEOLOGY

EXPLANATION 1 It'' Active normal fault--Hachures S/'41 1...... on downthrown side ..0/426*i<1-% niler • j Anticline 1•9,66 *. Bosin t..036«7 1 SSC »-#Vg16*r /* G'EN0t r-SIERRA 042. f. r•03•2*.':60- +I,. Charlie Canyon |ANTICLINEPELONA %%* BLUE .ROCK-.*G••642•ild.•·,% 4 !,•Ierl --·./ GR 0·4 Am - - C S' .Gr «'1»•» 17•=r'='·4,# /4.'K =e...... BIG PINE1*126.FAULT(14-km left slip -$0 •042•,1-TexasCanyon ::::%»•« ..9%"L restored)5 %06..:..>..e Basin -'ZZ>,U,-.a; . . 'S' e..C44%·1 :41f#..S r-//54*5%•*.*.•#fir•. ··:.4.:,•Q:b An Gb L 16:f.*- 0 30 KILOMETRES 4 1 1 .4.':&- I. © 06 .. 5/ 3,0 00YOO Figure 3.--Map showing proposed distribution of mid-Tertiary basins after palinspastic restoration of slip on the San Andreas, San Gabriel, and Big Pine faults. Arrows indicate transport directions; stipple indicates inferred depositional areas of basins. Ss, sandstone; C, conglomerate; Gr, granitid; GR, granite; Gn, gneiss; AG, augen gneiss; An, anorthosite; Gb, gabbro; L, Lowe Granodiorite; SFF, San Francisquito fault; VCF, Vasquez Canyon fault; PF, Pelona fault; AM, Abel Mountain; OM, Orocopia Mtns. of Miller (1946). Numbered areas refer to fig. 1. Lined pattern indicates present outcrop areas. \ north of the Lockwood Valley and Orocopia clinal feature. The San Andreas and San basins, occurs in the Plush Ranch, Texas Gabriel faults do not appear to have been Canyon, and Vasquez Formations, and the active during that time, but subsequent formation of Diligencia in an east-west right-slip movements on these fault zones granite province that apparently crosses. have displaced these features to their the Sierra Pelona-Orocopia anticlinal present positions. feature. Augen-gneiss exposures and clasts which occur south of the Big Pine fault, ACKNOWLEDGMENTS between the Texas Canyon and Vasquez Rocks basins and south of the Orocopia basin, do This paper was critically reviewed by likewise. Anorthosite gabbro and assoc- Tom Dibblee and Perry Ehlig, with addi- iated rocks occur adjacent to the Canton tional comments by John Crowell. Field Canyon, Vasquez Rocks, and Diligencia work was supported under N.S.F. grant basins, which received detritus from them. DES 71-00498(GA 30901) awarded to John Thus., the mid-Tertiary in southern C. Crowell. California appears dominated by east-west structural trends, which include normal faults and associated basins and uplifts and an actively forming and rising anti- 81 CALIFORNIA DIVISION OF MINES AND GEOLOGY

REFERENCES CITED Jahns, R. H., 1940, Stratigraphy of the easternmost Ventura basin, California, Atwater, Tanya, 1970, Implications of plate with a description of a new lower tectonics for the Cenozoic tectonics Of Miocene mammalian fauna from the Tick western North America: Geol. Soc. Canyon formation: Carnegie Inst. America Bull.,v. 81, no. 12, Washington Pub. 514, p. 145-194. p. 3513-3536. Kahle, J. E., 1966, Megabreccias and Carman, M. F., Jr., 1964, Geology of the sedimentary structures of the Plush Lockwood Valley area, Kern and Ventura Ranch Formation, northern Ventura Counties, California: California Div. County, California: California Univ., Mines S pec. Rept. 81, 62 p. Los Angeles, M.A. thesis, 125 p. Crowell, J. C., 1954, Strike-slip displace- Konigsberg, R. L., 1967, Geology along the ment of the San Gabriel fault, southern San Francisquito fault, Los Angeles California, in Chap. 4 of Jahns, R. H., County, California: California Univ., ed., Geology of southern California: Los Angeles, M. A. thesis, 84 p. California Div. Mines Bull. 170, p. 49-52. Miller, W. J., 1944, Geology of Palm 1962, Displacement along the San Springs-Blythe Strip, Riverside Andreas fault, California: Geol. Soc. County, California: California Jour. America Spec. Paper 71, 61 p. Mines and Geology, v. 40, no. 1, 1968, Movement histories of faults in p. 11-72. the Transverse Ranges and speculations 1946, Crystalline rocks of southern on the tectonic history of California, California: Geol. Soc. America Bull., ia Dickinson, W. R., and Grantz, A., v. 57, no. 5, p. 457-540. eds., Proceedings of conference on Poynor, W. D., 1960, Geology of the San geologic problems of the S an Andreas Guillermo area and its regional fault system: Stanford Univ. Pubs., correlation, Ventura County, California: Geol. Sci., v. XI, p. 323-341. California Univ., Los Angelesi M. A. 1973, Problems concerning the San thesis, 119 p. Andreas fault system in southern Calif- Remenyi, M. T.; 1966, Geology of the ornia, in Kovach, R. L., and Nur, Amos, Texas Canyon area, Los Angeles County, eds., Proceedings of the conference on California: California Univ., Los tectonic problems of the San Andreas Angeles, M. A. thesis, 97 p. fault system: Stanford Univ. Pubs., Sage, 0. G., Jr., 1973, Paleocene geog- Geol. Sci., v. XIII, p. 125-134. raphy of southern California: Calif- Crowell, J. C., and Susuki, T., 1959, ornia Univ., Santa Barbara, Ph. D. Eocene stratigraphy and paleontology, thesis, 250 p. Orocopia Mountains, southeastern Vedder, J. G., and Brown, R. D., Jr., California: Geol. Soc. America Bull., 1968, Structural and stratigraphic re- v. 70, no. 5, p. 581-592. lations along the Nacimiento fault in Ehlig, P. L., and Ehlert, K. W., 1972, the southern Santa Lucia Range and San Offset of Miocene Mint Canyon Formation Rafael Mountains, California, in from volcanic source along San Andreas Dickinson, W. R., and Grantz, Arthur, fault, southern California: Geol. Soc. eds., Proceedings of conference on America Abs. with Programs, v. 4, no. geologic problems of San Andreas fault 3, p. 154. system: Stanford Univ. Pub., Geol. Hill, M. L., and Dibblee, T. W., Jr., Sci., v. XI, p. 242-259. 1953, San Andreas, Garlock, and Big Pine faults, California--A study of the character, history, and tectonic sig- nificance of their displacements: Geol. Soc. America Bull., v. 64, no. 4, p. 443-458.