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THE SAN ANDREAS FAULT BETWEEN CARRIZO PLAINS AND TEJON PASS, SOUTHERN CALIFORNIA
By John C. Crowell Geological Sciences Department University of California Santa Barbara, CA 93106
ABSTRACT units have been identif ied across the San Andreas - San Gabriel fault The San Andreas fault at its system in Soledad Basin and the sharp bend in the northern Trans- Orocopia - Chocolate Mountain re- verse Ranges-separates very differ- gion, indicating about 300 km ( 180 ent rock terrains. North of the mi ) of right slip. fault basement rocks Consist of granites mainly of Mesozoic age· Emphasis in this paper is upon with Sierra Nevada affinities,· details observable along the San containing included remnants of Andreas fault zone, such,as fault Paleozoic metasediments. To the landforms, fault slices of many west the basement. is composed of ba- rock varieties, crushed rocks, and sic metamorphic rocks that may be upon the striking contrast in rock uplifted portions of ancient ocean- units across the fault zone as a ic crust. The sedimentary section whole. north of the fault begins with the marine Eocene Tejon Formation and INTRODUCTION is succeeded by a nearly complete sequence, including some interca- In approaching the Transverse lated volcanic rocks, up into'the Ranges along the San Andreas fault Pleistocene Series. Many of these from the northwest, the fault zone northern rock units change facies curves eastward into the Big Bend, from continental beds on the east and near Frazier Park has a due east- to deep-water marine facies on the west strike for a distance of about west where they are sharply trun- 6 km ( 4 mi ). The fault then curves cated by the San Andreas fault. gently southeastward across Tejon Pass and continues along the 'south- Southwest of the fault zone Pre- western margin of the Mojave Desert. cambrian gneisses and migmatites, As the fault enters the Big Bend re- gneisses of unknown age, and Meso- gion south of the Temblor Range its zoic granitic rocks of several surface trace climbs in elevation types are exposed. The Paleocene and crosses through basement terrain - Eocene Pattiway Formation and mid- in the Mount Pinos - San Emigdio Tertiary nonmarine beds and vol- Mountain - Frazier Mountain region canic units in the Caliente Range ( Figs. 1, 2 ). The Big Bend region and Cuyama Valley area are truncat- is also notable for the intersection ed on the northeast by the San An- of other major faults with the San dreas. Mid-Miocene and younger con- Andreas fault: the Garlock, Big glomerates and sandstones in the Pine, San Gabriel, and Liebre, for northern Transverse Ranges were de- example. Despite the conspicuous posited in intermontane valleys pattern of the Big Bend region on with sources to the northeast. A- geologic maps, the evolution and sig- cross the San Andreas fault in that nif icance of this complex area is direction no suitable source areas still unclear and much additional occur today. Suitable source areas investigation is needed. for these beds and counterparts to many of the southern basement-rock Rock units contrast markedly
223 CALIFORNIA DIVISION OF MINES AND GEOLOGY
across the San Andreas fault zone in ment rocks is composed of quartz this region. Basement rocks as well monzonite, quartz diorite, and dio- as overlying sedimentary sections rite, and constitutes the upper cannot be correlated directly across plate of the north branch of the the fault zone. Some matching se- Garlock fault. This major tectonic quences have been recognized out- movement zone, marked by mylonite side of the Big Bend region and and blastomylonite, is exposed in provide evidence for many miles of the Neenach Quadrangle ( Wiese, right slip on the San Andreas fault 1950; Peters, 1972 ) and dips to the system, including the San Gabriel north at about 50 degrees. It over- fault ( Hill and Dibblee, 1953; lies tectonically Pelona Schist, a Crowell, 1962, 1968, this volume; greenschist-facies sequence of pro- Wiebe, 1970; Ross, 1972; Huffman, bable Mesozoic age reconstituted 1972; Matthews, 1973 ). from graywacke, mudstone, some chert, carbonate rocks, and volcan- In the Carrizo Plains area on ic rocks ( Ehlig, this volume ). At the northwest sedimentary facies the eastern border of the Lebec contrast strongly across the fault Quadrangle, this north-dipping ma- ( Vedder, this volume ) and many jor fault is truncated by the south- fault landforms are well displayed dipping Pastoria thrust ( Crowell, ( Wallace, 1968; this volume ). To 1952 ), another major fault. The the southeast of Tejon Pass, part Pastoria thrust in turn is truncated of the thick sedimentary section on the south by the south branch of within Ridge Basin ( Crowell, this the Garlock fault, no doubt the volume ) is juxtaposed against principal strike-slip branch of the an eastward-thickening sequence of Garlock. Rocks in the upper plate very different sedimentary and vol- of the Pastoria thrust, and consti- canic strata. These units lying tuting the long ridge surmounted by north of the fault include the Tecuya Mountain and Santa Emigdio Neenach volcanic rocks and Miocene Mountain, consist mainly of gray sedimentary formations ( Wiese, 1950; granodiorite and quartz monzonite Crowell, 1952; Dibblee, 1967; with inclusions of marble and horn- Matthews, 1973 ). The fault zone fels. These Paleozoic (?) meta- itself through the. Big Bend region sedimentary rocks are best preserved is marked by scarps, sagponds, off- in roof pendants south of the Gar- set streams, and other fault land- lock fault; here, the limestone beds forms lying within a broad, con- have been intruded by coarse pink spicuous fault trough. The trough granite, quartz monzonite, and is primarily the result of long granodiorite. Basement-rock types erosion in fault-shattered rocks. cropping out in the westernmost This article is primarily concerned San Emigdio Mountains consist of with features within and along this gabbro, pyroxenite, hornblende quartz fault zone on a route followed by diorite, quartz gabbro, amphibolite, public roads. and metadiabase ( Hammond, 1958; Ross, 1970, 1972 ). These mafic and ROCK UNITS NORTH OF THE SAN ANDREAS ultramaf ic rocks may originally have FAULT been of suboceanic origin, whereas most of the eastern granitic rocks Basement rocks within the San north of the San Andreas fault Emigdio Mountains and southwestern appear similar to those of the south- part of the Tehachapi Mountains con- ern Sierra Nevada. Unfortunately, sist mainly of gneiss, schist, except for local studies, this sec- granitic and gabbroic rocks of sev- tor of basement rocks has not as yet eral types, and metasedimentary been investigated or mapped in rocks. Part of this strip of base- detail. 224 CALIFORNIA DIVISION OF MINES AND GEOLOGY
Sedimentary rocks lying unconfor- ROCK UNITS SOUTH OF THE SAN ANDREAS mably upon this basement terrain FAULT consist of a thick section of marine and nonmarine beds extending stra- Basement rocks south of the San tigraphically upward from the Eo- Andreas fault in the region of the cene Tejon Formation. On the west, Big Bend consist of various types beds of this Tertiary sequence are of gneiss, schist, and granitics. entirely marine up through the Plio- Work by Silver (1971) on lead- cene, but, eastward, the section uranium isotopes shows that blue- changes facies rapidly; Oligocene quartz bearing layered gneiss of and Miocene units, for example, are Frazier Mountain are between 1750 replaced laterally by nonmarine and 1680 m.y. in age, and were conglomerates ( Nilsen and others, intruded by porphyritic granodiorite 1973 )· During early and mid- and quartz monzonite between 1650 Tertiary times, prisms of sediments and 1680 m.y. ago. The latter rocks, with mainly north-south facies now consisting of distinctive augen trends were laid down facing the gneisses, were metamorphosed about sea on the west; these beds are now 1425-1450 m.y. ago, and then intrud- upturned as the result of the ele- ed by gabbro, diorite, and minor vation of the San Emigdio - Teha- anorthosite about 1220 m.y. ago. chapi Mountains in Pleistocene These definitely Precambiran rocks time. The outcrop secti.on in map are best viewed on Frazier Mountain view today in the foothills dis- ( Fig. 2, locality 23 ), and along plays a sequence passing from con- Lockwood and Piru Creeks. Other tinental beds on the east into multiple deformed gneisses, not yet deep-water marine deposits on the dated isotopically, are well exposed west ( e.9-., Hammond, 1958; Nilsen, along the roads to the tops of Mt. 1973; Nilsen and others, 1973 ). Abel ( Fig. 1, locality 9 ) and to Mt. These marine units reach to the Pinos ( Fig. 2 ). Granitic rocks of San Andreas fault in the Temblor several types and ages also occur Range ( Vedder, this volume ), and in the region ( e.9-., Crowell, 1964; in the northern part of the San Carman, 1964; Lofgren, 1967; Evern- Andreas sector described in this den and Kistler, 1970; Ross, 1972 ). article ( Fig. 1 ). Except for the Pelona Schist lying along the north flank of the Mt. Volcanic rocks in this northern Abel - Mt. Pinos ridge, none of these sector include Lower Miocene basalt basement rocks appear similar to and porphyritic dacite and Upper those north of the San Andreas fault. Miocene andesite, dacite, and rhyo- On the other hand, many of the dis- lite. The latter rocks, belonging tinctive Precambrian rocks are cor- to the Neenach - Pinnacles volcan- related with those of Soledad Basin ic assemblages, occur as slices and the Orocopia Mountains, and are within the fault segment described interpreted as displaced by the San herein, and are now found in inter- Andreas - San Gabriel fault system mediate positions with respect to ( Crowell, 1962, this volume ). their major outcrop areas in the Pinnacles National Monument of the Sedimentary and volcanic rocks northern Gabilan Range, and the exposed south of the San Andreas southern margin of Antelope Valley fault in the Big Bend region consist ( Huffman, 1972; Matthews, 1973 ). of marine Paleogene beds, and of This volcanic field has apparently continental mid-and late-Tertiary been sliced through and displaced strata with some i.n t.ercalated about 315 km ( 195 mi ). canic rocks. Paleocene and Eocene
225 CALIFORNIA DIVISION OF MINES AND GEOLOGY
sandstone and shale ( Dibblee, 1973; San Andreas fault zone from the Carman, 1964; Vedder, this volume; Carrizo Plains ( Wallace, this vol- Howell, this volume ) are preserved ume; Vedder, this volume ) to the locally. Paleocurrent and pro- Tejon Pass region. Landforms re- venance studies of the Paleocene sulting from recent faulting, in- strata suggest derivation of these cluding the 1857 Fort Tejon Earth- clastic sedimentary rocks from quake ( Wood, 1955 ), are conspicu- across the fault zone ( Sage, 1973, ous ( Vedder and Wallace, 1970 ), this volume ). Mid-Tertiary non- as are fault slices of many rock marine units, with interbedded ba- types. Detailed strip maps along salt flows, were deposited in ir- this route have been published in regular basins now disrupted by Crowell ( 1964). Localities dis- subsequent tectonic displacements playing special features are also ( Bohannon, this volume ). The mid- described here and shown on Figures dle and upper Miocene stratigraphic 1 and 2 by circled numbers. section in the Caliente Range and Cuyama Valley ( Vedder, this volume ) BIG PINE FAULT thins and changes facies toward the Mt. Abel region, where it is The Big Pine fault can be nonmarine ( James, 1963; Carman, followed westsouthwestward from its 1964; Crowell, 1964 ). The Miocene intersection with the San Andreas Caliente and Pliocene Quatal for- fault near Lake of the Woods into mations were deposited in broad the Santa Maria Valley, and probably intermontane valleys, and received all the way to the Pacif ic Ocean debris from regions to the north- ( S. C. Comstock, personal comun., east across the San Andreas fault, 1974 ). It has had a long and com- and now offset ( Barker, 1972 ). Con- plex history involving dip slip in glomerate studies show, for example, the early Miocene and left slip of that stones in the Caliente Forma- about 13 km ( 8 mi ) in post-late tion are closely related in pro- Miocene time ( Hill and Dibblee, 1953; venance to those of the Mint Can- Poynor, 1960; Crowell, 1962, p. 34; yon Formation of the Soledad Bas- Carman, 1964; Kahle, 1966; Bohannon, in ( Carman, 1964; Ehlig and Ehlert, this volume ). Some subdued scarps 1972 ), and that these in turn were at places along the fault may be probably derived from source areas due to Recent displacements; inter- in the Orocop.ia-Chocolpte Mountains pretations of these landforms show, region now northeast of the Salton however, that this fault is not as Sea ( Ehlig and others, this volume ). active as the San Andreas. Beds of the Quatal Formation can be traced eastward around the south GARLOCK FAULT flank of Frazier Mountain into units of the Hungry Valley Forma- From its intersection with the tion of the Ridge Basin section San Andreas fault near Tejon Pass, ( Crowell, 1964, p. 12; this vol- the Garlock fault can be traced ume ). Braod disected Pleistocene eastward for 260 km ( 160 mi ) to the fanglomerates, sloping away from Death Valley region. Through the higher mountains and lying uncon- Tehachapi Mountains it follows a formably on the Quatal and Hungry linear topographic depression but Valley formations, are conspicuous landforms within it are subdued and throughout the region. the result of differential erosion rather than of recent fault activity. SAN ANDREAS FAULT ZONE Fresh scarps due to recent faulting are present in the Mojave Desert to Public roads closely follow the the east, however ( Hill and Dibblee,
226 CALIFORNIA DIVISION OF MINES AND GEOLOGY
1953; Smith, 1960; Dibblee, 1967 ). sag pond. Excellent fault land- Offset dike swarms, matching se- forms are found on to the north- quences of metasedimentary rocks, west ( Wallace, 1968, this volume ). and other features in the desert Shattered masses of plutonic and suggest a total left slip on the metamorphic rocks, probably slices Garlock fault of about 65 km ( 40 mi ) of basement within the San Andreas ( Smith, 1962; Smith & Ketner, 1970; fault zone occur on a ridge to the Davis and Burchfield, 1973 ). Be- southwest of the road ( Vedder, 1970, cause the histories and character- outcrop marked pKc ). istics of rock units along the Gar- lock and Big Pine faults are very 2. ( Crossing of San Andreas differen.t it is unlikely that they fault by Hwy 33 and 166, northeast constitute a conjugate mechanical of Reyes Service Station ). The system ( Crowell, 1962; this vol- San Andreas fault is marked by two ume ). narrow fault valleys with a fault ridge (horst) between them. OTHER FAULTS 3. ( Cerro Noroeste Road lead- The Abel Moontain - Mt. Pinos ing to Abel Mountain by way of Patti- block of basement rocks has been up- way Ridge ). Scarps along the San lifted and thrust relatively west- Andreas fault zone face both north- ward across beds of the Miocene east and southwest; fault traces Caliente Formation ( Ziony, 1958; converge and diverge in map view. Crowell, 1964, p. 14 ). On the Note fault depressions and desiccat- south, this thrust passes into ed sag ponds. several tear faults with a geometry suggesting that the terrain between 4. ( Viewpoint on curve of the San Andreas and Big Pine faults climbing road, near milepost 5 ). has been squeezed upward and west- Views of Cuyama Valley, Caliente ward. The San Gabriel fault and Range, Carrizo Plain, and Temblor Frazier Mountain thrust system are Range. Trace of San Andreas fault described brief ly by Crowell ( this zone clearly visible. Outcrops of volume ). Paleocene-Eocene Pattiway Sandstone in roadcuts and on hillsides ( Sage, EXCORSION GUIDE this volume ).
According to their designation 5. ( Turnout on Cerro Noroeste on Figures 1 and 2, 32 localities Road near entrance monument to Los are described brief ly below where Padres National Forest, about 9.6 mi signif icant geological features from Hwy 33 and 166 ). On the east, can be obserVed. For more precise deeply dissected terrain a.long trib- locations, refer to the strip maps utaries of Santiago Creek, with in Crowell (1964) or to U.S. Geol- trace of San Andreas fault zone ogical Survey quadrangles ( Apache prominent. In the roadcut, non- Canyon, Ballinger Canyon, Cuddy marine conglomeratic sandstone ( buff Valley, Cuyama, Eagle Rest Peak, and reddish ) of the Oligocene - Frazier Mountain, Lebec, Santiago Lower Miocene Simmler Formation (0s) Creek, and Sawmill Mountain ). Dis- is overlain by marine brown silt- tances in miles. stone of the Miocene Soda Lake Formation (Ms) containing yellowish 1. ( Drive northwestward from calcareous concretions. Both units Hwy 33 and 166 for about 2 mi on dip easterly at about 30 degrees Soda Lake Road from Reyes Service and are overlain unconformably by Station ). Note fault scarps along gravels of the Pliocene Quatal For- the San Andreas fault zone and dry mation ( also called Paso Robles For-
227 CALIFORNIA DIVISION OF MINES AND GEOLOGY ElI .....49' /5 > --ao. 1 , E··./L , *·a.i-f •'•6 \ 22 0 SO i. •ri,8056%-Q 6•1• 2 g ,254 5 Objill 0. 6. . 1,9',9 1, /- i#CL •• 6 4/ ...'4' N -,O • <»E - t.. E 3,
228 CALIFORNIA DIVISION OF MINES AND GEOLOGY
Figures 1 and 2. Adjoining strip trace of the fault can be followed maps from Grocer Grade on Highway across its lower third. 33 and 166 on the northwest to Gorman on the southeast. Geology 7. ( Cerro Noroeste Road near simplif ied and modif ied from turnoff to Camp Condor ). Exposures Crowell ( 1964). Basement rock of Miocene Caliente Formation ( con- symbols: gb = gabbro; py = glomeratic sandstone ) faulted against pyroxenite; gd = granodiorite; qd = Pelona Schist. quartz diorite; qm = quartz monzon- ite; gr = granite; gn = gneiss, 8. Sharp curve in road and deep agn = augen gneiss; m = mainly roadcut ). .Pelona Schist fdulted marble; h = mainly hornfels; md = against -gneiss and migmatite. Some metadiorite; sch = Pelona Schist. zones of mylonite and blastomylonite Sedimentary and volcanic rocks: in the gouge of this fault zone sug- Ep = Paleocene and Eocene Pattiway gest either recurrent movement or Formation; Et = Eocene Tejon that fault slices of an older fault Formation; E = Eocene formations have been tectonically carried into undifferentiated; 0e = Oligocene their present position.here. San Emigdio Formation; 0s = Oligo- cene - Lowet Miocene Simmler Forma- 9. ( Summit of Abel Mountain; tion; Mt = Miocene Temblor Forma- campground ). Exposures of rodded tion; Mm = Miocene Monterey Forma- gneiss, migmatized at places and tion; Msm = Miocene Santa Margarita multiply deformed. Formation; Ms = Miocene Soda Lake Formation; Mc = Miocene Caliente 10. ( Quatal Canyon Road, down Formation; Mv = Miocene volcanic canyon from Toad Spring Campground ). rocks; Pq = Plio-Pleistocene Quatal Reddish schist-bearing sedimentary Formation; Ph = Plio-Pleistocene breccia of Miocene Caliente Forma- Hungry Valley Formation; PQc = tion. Facies changes and clast Pliocene - Quaternary continental imbrication show derivation of deposits; Q = Quaternary deposits, these sediments from the north; mostly alluvium and terrace debris; from a source across the San Andreas Ql = Landslides; Qt = Quaternary fault and now disappeared, probably terraces or high-standing fans. displaced by right slip ( Barker, 1972 ). The breccia interfingers with typical Caliente sandstone and mation ) that dip westerly at about conglomerate along Quatal Canyon. 30 degrees. Between this locality and Stop 6 there are excellent 11 and 12. ( Mill Potrero - Pine views northwestward and downward Mountain Club region ). Prominent into the imposing canyon eroded by scarps, offset streams, and other Santiago Creek. Note the tight fault landforms along the active syncline paralleling the main San San Andreas fault at the base of Andreas fault; the fault lies ad- San Emigdio Mountain, and through part of the Pine Mountain Club jacent to it on the north. development. Note many long fault slices on the steep hillside, in- 6. ( Forest Service roads and cluding Miocene sedimentary units access roads to quarries ). Cata- and plutonic and metamorphic rocks. clastic rocks and fault slices with- Groundwater in this region is partly in the San Andreas fault zone. A dammed by gouge zones along the fault large landslide from the high ridge zone paralleling the road through on the north side of Santiago Can- the valley. yon has been cut by recent move- ments on the San Andreas fault; the
229 CALIFORNIA DIVISION OF MINES AND GEOLOGY
13· ( Tributary to San Emigdio of the 1857 Fort Tejon Earthquake. Creek ). Fault slices of marine Mio- Road to Mt. Pinos takes off from cene Temblor Formation ( sandstone near divide between San Emigdio and shale ). Slices of hornfels and Canyon and Cuddy Valley; this is plutonic rocks. an instructive side trip. Along the road are good exposures, first 14. ( Continuing eastward along of Pelona Schist, and then ( to the road toward Cuddy Valley ). Slices south ) of gneiss and granitic of Miocene Caliente Formation ( non- rocks. marine conglomeratic sandstone ) south of the active trace of the 18. ( Cuddy Valley ). Fault San Andreas fault and north of a scarps, fault-depressed segments, steeply south-dipping fault that desiccated sagponds, and other fault has tectonically emplaced Pelona features. Forest Service roads pro- Schist above the sandstone. Fan- vide access to Tecuya Ridge on the glomerate deposits from Mt. Pinos north where granodiorite and quartz slope valleyward, unconformably monzonite are exposed along with in- above the schist, sandstone, and clusions of marble and hornfels. south-dipping fault. These fang- lomerate beds are in turn cut by 19. ( Narrows between Cuddy Val- the near-Vertical San Andreas ley and Cuddy Canyon ). Prominent fault zone. A main tributary of fault topography and incised drain- San Emigdio Creek is sharply off- age arrangement along the San An- set to the right for nearly a half- dreas fault. mile at Locality 14, near the Jim Whitiner Tree ( a giant ponderosa 20. ( Roadcuts west of Lake of the pine, 20 feet in circumference and Woods settlement ). Brecciated augen 142 feet high ). gneiss, that probably occurs as slices within the Big Pine fault 15· ( Turnout on road with view zone near its intersection with the down San Emigdio Canyon to the San San Andreas fault. This rock is Joaquin Valley ). Prominent thick similar to that on Frazier Mountain beds of Eocene and Oligocene sand- to the south, and to augen gneiss stone lie unconformably upon base- in Soledad Basin and the Orocopia ment rocks and form sharp peaks Mountains ( Crowell, 1962; this vol- north of Antimony Peak, including ume ). Eagle Rest Peak in the Devil's Kitchen area. Old mines on Anti- 21. ( Road to Lockwood Valley and mony Peak were worked first by westward ). Faint fault scarps along Indians and were examined by W. P. Big Pine fault near Cuddy Ranch, Blake, an early California geolo- opposite road to Chuchupate Camp- gist, in 1857 ( Jermain and Ricker, ground and summit of Frazier Moun- 1949; Troxel and Morton, 1962, p. tain. 56 ). 22. ( Forest Service road to 16 to 17· ( Road follows along Tecuya Ridge ). Paleozoic (?) meta- hillside above San Emigdio Creek in sedimentary rocks are preserved as approaching divide into Cuddy Val- inclusions of marble and hornfels ley ). Road constructed along trace in granodiorite and quartz monzo- of fault with several sag ponds hite. ( mostly dry and alluviated ), shut- ter ridges, and offset .streams. 23· ( Road to summit of Frazier Much of the pnominent fault topo- Mountain ). Gneiss, augen gneiss, graphy here is probably the result and migmatite. Excellent regional
230 44///3:43·1",-rf«p...... :
CALIFORNIA DIVISION OF MINES AND GEOLOGY
view from top. flank of Frazier Mountain ). The Frazier Mountain thrust has emplaced 24. ( Frazier Mountain Park., Precambrian gneiss on top of steep- especially east and southeast of ly dipping Plio-Pleistocene con- own ). Fault topography, fault glomeratic sandstone beds of the ridges, scarps, elongate fault de- Hungry Valley Formation ( Crowell, pressions and incipient pull-aparts. this volume ). The thrust is over- lapped by conspicuous fans high on 25· ( On eastward for several the mountain slope. These terrace miles from Frazier Mountain Park ). surfaces apparently correlate geo- Excellent fault landforms along the morphically with the subdued sur- San Andreas, including shutter face surmounting the ridge north ridges and offset streams. of Gorman and with remnants between Tecuya Mountain and Lebec. 26. ( Gullies beneath terrace de- posits ). Exposures of basement 32. ( Hill southeast of Gorman ). rocks in this region show that the A large landslide or small thrust Garlock fault meets the San Andreas plate of broken-up rock, ,mainly fault at a high angle. consisting of granodiorite with masses of marble and hornfels in- 27. Summit of Tejon Pass, at cluded within it s.urmounts this Interstate 5 crossing ). Slices of hill. The mass presumably slid marble, hornfels, sheared and from a high ridge squeezed up with- comminuted granodiorite, granite, in the San Andreas fault zone. quartz monzonite, Miocene andesite, Since emplacement, however, the and gray conglomeratic sandstone of San Andreas has moved again. Young the Plio-Pleistocene Hungry Valley landslides have carried some of Formation ( Ridge Basin section ), this older landslide or thrust along with other rock types, occur debris downslope to the present between here and Stop 30. The prin- active San Andreas fault zone along cipal break of the San Andreas fault Interstate 5. is marked at the pass by several feet of black gouge separating ACKNOWLEDGMENTS orange Quaternary terrace deposits on the north from comminuted and B. M. Crowe and Gordon Haxel sheared granodiorite on the south. helpfully reviewed the manuscript.
28. ( Curve in Interstate 10 be- REFERENCES CITED tween summit of Tejon Pass and Gor- man town ). Large landslide from Barker, J. M., 1972, Geology and rides to north has slid across the petrology of the Toad Springs San Andreas fault, and then has been Breccia, Abel Mountain, Califor- displaced by later movements on the nia, and its relation to the San fault. Andreas fault: Unpub. M.A. 29 and 30. ( Hillside north of thesis, Univ. Calif., Santa Gorman ). Slices of a variety of Barbara, 100 p. rock units within a locally broad Carman, M. F., Jr., 1964, Geology lens of the San Andreas fault zone. of the Lockwood Valley area, These include rocks similar to those Kern and Ventura Counties, Cal- at Stop 27 ( refer to map, Crowell, ifornia: Calif. Div. Mines 1952 ). Spec. Rpt. 81, 62 p. Crowell, J. C., 1952, Geology of 31. Canyons beneath high fans o n the Lebec quadrangle, California:
231 CALIFORNIA DIVISION OF MINES AND GEOLOGY
Calif. Div. Mines Spec. Rept. 24, Jr., 1953, San Andreas, Garlock 23 P' and Big Pine faults, California: ---1962, Displacement along the San Geol. Soc. America Bull., v. 64, Andreas fault, California: Geol. P. 443-458. Soc. America Spec. Paper 71, Huffman, 0. F., 1972, Lateral 61 p. displacement of Upper Miocene ---1964, The San Andreas fault rocks and the Neogene history from the Temblor Mountains to of offset along the San Andreas Antelope Valley, southern Cali- fault in central California: fornia: San Joaquin Geological Geol. Soc. America Bull., v. 83, Society Guidebook, p. 7-39. p. 2913-2946. ---1968, Movement histories of James, G. T., 1963, Paleontology faults in the Transverse Ranges and nonmarine stratigraphy of and speculations on the tectonic the Cuyama Valley Badlands, Cal- history of California: Stanford ifornia: Univ. Calif. Pubs. in Univ. Pubs. Geol. Sci., v. 11·, Geol. Sciences, v. 45, 171 p. p. 323-341. Jermain, G. D., and Ricker, Davis, G. A., and Burchfiel, B. C., Spangler, 1949, Investigation 1973, Garlock fault: an intra- of Antimony Peak, Kern County, continental transform structure, California: U. S. Bur. Mines southern California: Geol. Soc. Rept. Inv. 4505, 5 p. America Bull., v. 84, p. 1407- Kahle, J. E., 1966, Megabreccias 1422. and sedimentary structures of Dibblee, T. W., Jr., 1967, Areal the Plush Ranch Formation, geology of the Western Mojave northern Ventura County, Cali- Desert, California: U.S. Geol. fornia: Unpub. M.A. thesis, Survey Prof. Paper 522, 153 p. Univ. Calif., Los Angeles, 125 p. ---1973, Regional geologic map of Lofgren, G. E., 1967, Geology of San Andreas and related faults the Mount Pinos basement complex in Carrizo Plain, Temblor, ( Abstract): Geol. Soc. America Caliente, and La Panza Ranges Spec. Paper 115, p. 337. and vicinity, California: U.S. Matthews, Vincent, 111, 1973, Pin- Geol. Survey, Misc. Geol. In- nacles - Neenach correlation: vestigations Map 1-757. a restriction for models of the Ehlig, P. L., and Ehlert, K. W., origin of the Transverse -Ranges 1972, Offset of Miocene Mint of the big bend in the San Andreas Canyon Formation from volcanic fault: Geol. Soc. America Bull., source along the San Andreas v. 84, p. 683-688. fault, California: Geol. Soc. Nilsen, T. H., 1973, Tejon Forma- America, Abs. with Programs, tion - description of field trip v. 4, p. 154. stops and road-log from Gorman Evernden, J. F., and Kistler, R. W., to Taft: Pac. Sec. Soc. Econ. 1970, Chronology of emplacement Paleon. and Mineralogists, of Mesozoic batholithic complexes Guidebook, Trip 2, p. 23-34. in California and western Nevada: Nilsen, T. H., Dibblee, T. W., Jr., U.S. Geol. Survey Prof. Paper and Addicott, W. 0., 1973, Lower 623, 42 p. and middle Tertiary stratigraphic Hammond, P. E., 1958, Geology of units of the San Emigdio and the lower Santiago Creek area western Tehachapi Mountains, Cal- San Emigdio Mountains, Kern ifornia: U.S. Geol. Survey Bull. County, California: Unpub. M.A. 1372-H, 23 P. thesis, Univ. Calif., Los Ange- Peters, C. M. F., 1972, A structural les, 108 p. interpretation of the Garlock Hill, M. L., and Dibblee, T. W., fault zone at the Tehachapi
232 CALIFORNIA DIVISION OF MINES AND GEOLOGY
the Garlock fault, southern Cal- crossing: Amer. Inst. Mech. ifornia, suggested by offset Engineers, Proc. of conference sections of similar metasedi- on rapid excavation and tunnel- mentary rocks: U.S. Geol. Sur- ing, p. 133-155. vey Prof. Paper 700-D, P. Dl-D9. Poynor, W. D., 1960, Geology of the Troxel, B. W., and Morton, P. K., San Guillermo area and its re- 1962, Mines and Mineral re- gional correlation, Ventura sources of Kern County, Califor- County, California: Unpub. M.A. nia: Calif. Div. Mines and thesis, Univ. Calif., Los Angel- Geology, County Rept. 1, 370 P. es, 119 p. Vedder, J. G., 1970, Geologic map Ross, D. C., 1970, Quartz gabbro of the Wells Ranch and Elkhorn and anorthositic gabbro: mark- Hills quadrangles, San Luis ers of offset along the San An- Obispo and Kern Counties, Cali- dreas fault in California Coast fornia: U.S. Geol. Survey Misc. Ranges: Geol. Soc. America Geol. Investigations, Map 1-585. Bull., v. 81, p. 3647-3662. Vedder, J. G., and Wallace, R. E., ---1972, Petrographic and chemical 1970, Recently active breaks reconnaissance study of some along the San Andreas fault be- granitic and gneissic rocks near tween Cholame Valley and Tejon the San Andreas fault from Bo- Pass, California: U.S. Geol. dega Head to Cajon Pass, Cali- Survey Misc.Inv. Maps 1-574. fornia: U.S. Geol. Survey Prof. Wallace, R. E., 1968, Notes on paper 698, 92 p. stream channels offset by the Sage, 0. G., Jr., 1973, Paleocene San Andreas fault, southern geography of southern California:, California: Stanford Univ. Pubs. Univ. Calif., Santa Barbara, Geol. Sci. v. 11, p. 6-21. doct. dissertation, unpublished, Wiebe, R. A., 1970, Pre-Cenozoic 250 P. tectonic history of the Salinian Silver, L. T., 1971, Problems of Block, western California: Geol. crystalline rocks of the Trans- Soc. America Bull., v. 81, p. verse Ranges: Geol. Soc. Amer- 1837-1842. ica, Abs. with Programs, v. 3, Wiese, J. H., 1950, Geology and P. 193-194. mineral resources of the Neenach Smith, G. 1., 1960, Time of the quadrangle, California: Calif. last displacement on the middle Div. Mines Bull. 153, 53 P. part of the Garlock. fault, Cali- Wood, H. 0., 1955, the 1857 earth- fornia: U.S. Geol. Survey Prof. quake in California: Seismol. Paper 400-8, p. 8280. Soc. America Bull., v. 45, p. ---1962, Large lateral displacement 47-67. on the Garlock fault, California Ziony, J. 1., 1958, Geology of the as measured from offset dike Abel Mountain area, Kern and swarm: Am. Assoc. Petroleum Ventura Counties, California: Geologists Bull., v. 46, p. 85- Unpub. M.A. thesis, University 104. of California, Los Angeles, Smith, G. 1., and Ketner, K. B., 1970, Lateral displacement on 99 P.
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