"TV, " BERKELEY RE" RETURN EARTH SCIENCES LIBRARY LIBRARY f EnethLh Cai R A** ~I907 UNIVERSITY OF CALIFORNIA GEOLOGY OF THE NORTHERN SANTA ANA MOUNTAINS, CALIFORNIA BodfT Sierra Peak View north up Ladd Canyon; Bedford Peak on right. Ridge from lower left to center is formed by unturned beds of Baker Canyon Conglomerate Member of the Ladd Formation; slopes in right half of view underlain by Santiago Peak Volcanics. Geology of the Northern Santa Ana Mountains, California By J. E. SCHOELLHAMER, J. G. VEDDER, R. F. YERKES, and D. M. KINNEY GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA G:F 0. L-O G CA L- -$ ° U-RV-E Y- PR OFE § SFO NA L PA PER- 42 0 - D A study in stratigraphy, structure, and structural evolution of the northern Santa Ana Mountains UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1981 UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director Library of Congress Cataloging in Publication Data Geology of northern Santa Ana Mountains, California. (Geological Survey Professional Paper; 420-D) Bibliography: p. D67-D7O0 Includes index. Supt. of Does, no.: . I 19. 1. Geology--California--Santa Ana Mountains. I. Schoellhamer , J. E. II. Series QE90.S15G46b 551.7'09794'96 81-607011 AACR2 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page NDS ACL L. L loo. oa ias ev nevus reuses» D1 IMFOGUCHON - "z.. nT. .o oen bec cinereus 1 . ... «el conc ees 2 Jurassic System... AFH as 3 Middle Jurak8IC . ... . 1 : -_ neice 3 Bedford Canyon Formation.::......:.:...._..__.._._.__ 3 Jurassic(?) and Cretaceous Systems .__________________________.____. 5 Upper Jurassic(?) and Lower( ?) Cretaceous Series ___.... 5 Santiago Peak Volcanics and related intrusive TOCRKS Lele 5 Volcanic "slate chip" breccia ...___________._._. 7 Pacite{2) PLOW . ..... 10. 20. Anion ras ren 8 Tull? Hl. abe eventer one bee resect 8 Andesite flows and flow breccias..._._____.._. 8 Dacite porpHYTY - ..o cl oll eee ere eee Ceva en 9 Alteration and metamorphism......._..._..._.. 10 .. 2.0 10 EPIdOMEERON 222 curr ce crece 10 Age and 11 Cretaceous GySLEM 2222.2 202 1 Ll nle inne nes n ne as 11 Upper Cretaceous . ._. ... Ll nee cee nne 11 Trabuco -L-. 11 .o non lone nn eee eee nee nev 11 Ladd FOFMAMIONLL : 1 e 222 LL er cera reel e nec ass 12 Baker Canyon Conglomerate Member ...... 13 Holz Shale 15 Wiliams FOTMALION . olen onnec ele ce icc ce.. 17 Schulz Ranch Sandstone Member 17 Pleasants Sandstone Member ..._._.__.__.__.._ 19 Tertiary System _..........._.. a+ 21 Paleocene 3 21 Silverado cause 21 Stratigraphy and lithology ........_.___.__._.._.. 22 Unit A, basal conglomerate ._.._._.__.._ 22 Unit B, sandstone and siltstone........ 22 Unit C, Claymont Clay Bed ._____.__.... 28 ...le 24 Unit D, uppermost sandstone, silt- stone and conglomerate; Serrano Clay Bed.......__... 26 Type region northeast of Irvine ces 26 Northeast of Irvine Lake....._.. 26 North-central area - Fremont Canyon to Santa Ana River. 26 Northeast of Whittier fault...... 27 Area southeast of Black Star 27 Age ARA COTTEIRMONLE . creer en reer 28 SETICS +... _.. leno noone roe enne rre eben eb ness nies 28 Santiago FormALION ..; .. 00.00 el 28 Stratigraphy and lithology 29 Basal conglomerate ............_......._.. 29 Strata above basal conglomerate.... 30 ..... 30 Subsurface distribution ...._..._.___.._..._.__. 31 Age and 31 Page Tertiary System-Continued Eocene( ?) to Miocene Series...________________________.___._.__. D31 Upper Eocene( ?) to lower Miocene...________________ 31 Sespe and Vaqueros Formations, undifferen- neenee cers 31 Stratigraphy and lithology ........_..... 32 Basal conglomerate .___________. 32. Sandstone and conglomerate sandstonge-...:................ 34 Upper conglomerate ____________ 34 UPDET CONLACE ..... 34 Subsurface distribution ____.___.________. 36 Age and correlation .___.______.___________ 36 Regional importance of upper contact - 36 MIOCENCSETIGE 2-2 2. onine ces 37 Middl@MIOCENG ... .... erin ener ch 37 Topanga ForMabion--..-.._.__cll.___lll.......c. 37 Stratigraphy and lithology ......._..._.. 37 Basal conglomerate ____________. 37 Sandstone and conglomerate 37 Upper contact .........l..l..l.__.l.l.:l.l.. 39 Subsurface distribution ..___.____.__.__.__ 39 Age and correlation ..._.._._._._.._._._.... 39 El Modeno Volcahics .._.............._.__.__...! 39 Associated igneous rocks .__._.________._ 40 Age and cofrelation..................... 40 Middle and upper Miocene .__._._.____.__________.___.____ 41 Monterey Shale 41 AEL ALL l. .ll enlace lenee 42 Puente 42 La Vida Member........................_ 42 Stratigraphy and lithology ..... 43 Basal contact and as- sociated rocks .____._. 43 Siltstone and sandstone. 43 Soquel 46 Yorba 49 Sycamore Canyon Member.._........... 50 Miocene and Pliocene 52 Upper Miocene and lower Pliocene ..__.__._________._ 52 Capistrano Formation..-.__..:_._..___._..___._._. 52 Oso Member :.....}.s...2.........c..cly 52 PlHocene Series ...... 22.20. LIL ATLAN ELE ral nen ane wass 53 Fernando Pormation 53 LOWETMEMDET _... cache. se 53 Upper member 56 Niguel FOFMALIONL 2.2. ece neu 57 Quaternary BySLEM L-. ne sonic 59 BErIGE ... rere ..o, nlc. bens 59 Lo Habra FOrmMabHONn ... cc oll ecole nee 59 Pleistocene and Holocene Series __________.__________________. 60 Terrace 1 oen Leen ece bel e 60 Deformed alluvial deposits_...______________.__ 60 Older alluvium .... enne c ien i denes 61 Younger AlMVIUN]L 20-2 -c. 2200s ne nn Doen nere 62 VI CONTENTS Page Page SHUCHAPEC: 22.1 222.2200 21 e oud. n rasa oen ie eed ien iod D63 | Supplemental information-Continued Regional structure pattern. .... ..o ARAI. ILL. 63 List of microfossils-Continued Northeast of Whittier-Elsinore fault ..__.___.__.________ 63 Miocene-Continued Southwest of Whittier-Elsinore fault ....._.__.____.___ 63 Puente Formation-Continued Exposed structures :_.:.. selle rse ener 63 Yorba D98 Subsurface structures south of El Modeno fault .... 65 La Vida and Yorba Members, Subsurface structures north of El Modeno fault .... 66 undifferentiated ..._....._....._ 99 Summary and regional interpretations 67 . ... 22 ens ene e een e AEE ece 99 References CiLOd......1:1.. ..: il rans ne shane a's bwes anal s 67 Fernando 99 Supplemental information 2.1 .... . .. 222 nee eee can vibe slane 71 . sut cloe or neve ne con 99 Well locations and related data ...._._._____._._________.___.__._._. 72 TALE . 22.2. . .nl AYE eco 99 List Of megafOS81]8 . . .. «2.20. nu nese es eens s 82 Ladd Formation -L. .. .... .o... senco cern 99 Late >: -on ltl ces 82 Baker Canyon Conglomerate Member _ 99 Ladd FOPMAION .. ll... 82 Hol: Shale Member .._....._.:__....__.._ 100 Baker Canyon Conglomerate Member _ 82 Williams FOrMALION. 101 Holz Shale Member ....._.._........_... 83 Schulz Ranch Sandstone Member ._... 101 Williams Formation........................_.... 85 Pleasants Sandstone Member.......... 101 Schulz Ranch Sandstone Member ..... 85 Pal@OCENC. . 23. .o. IEA Lee en Pleasants Sandstone Member.......... 86 Silverado Formation...-;....ccicclcllll.lll..l.l.l 103 Paleocene: . .l) c SA e se ieee ae ee av ia nae evie sian 89 BOCENE y-... cc ee 103 Silverado Formation ............................ 89 Santiago 103 nere fers renee red de ie con cn cx awe 90 Eocenel ?) to 104 Santiago Formation.....................l..l... 90 Sespe and Vaqueros Formations, undifferen- FEocene( ?) to MIOCENE ernie. 92 tiated __. ma 104 Sespe and Vaqueros Formations, undiffer- Miocene e Ape ee 105 .ll eno evie vee abbas n 92 Topanga Formation 105 MiGCENC:: .. oes aa deaden na becn thanh 93 PHhocene.. .... neuen ele rial res eli teck en en 106 Topanga Formation -.. 93 Fernando 106 eer elisa coe sei ener eee ress 96 Lower member 106 Fernando Formation 96 Microfessil localities . _c .... .l loci el esen cen. 106 List Of rele 97 MIGCENC.......c..c-eernce notes 106 Miocene r 97 Topanga 106 Topanga Formation.......c..--:.-.....-.......- 97 FiModeno Volcani¢s 107 EI Modenc Volcanics .................._....___._. 97 Monterey Shale .-.. 107 Monterey Shale 97 Puente 107 Puente 97 Pliocene... <- 107 LaVida Member........c........__..____ 97 Fernando 107 La Vida and Yorba Members, Lower member 107 undifferentiated ..........._...... 98 Index ' tas s cns 109 ILLUSTRATIONS [Plates are in pocket] FRONTISPIECE. View north up Ladd Canyon. Prare 1. Geologic map of the northern Santa Ana Mountains. | 2. Structure sections A-C, A-H, B-N,; A-K, E-L, H-O , L-Q. 3. Structure sections G-J, R-S, L-P, U-W, M -F, U-V , T-X. 4. Columnar sections of the lower part of the Silverado Formation. Page FIGURE 1. Outline map of Los Angeles basin .____._________.___________.. i sors al «ore de beers brk on D2 2. Generalized physiographic map of northern Santa Ana Mountains showing geographic names._..________________________.. 4 3. Generalized stratigraphic section of northern Santa Ana MOUnt@in$s Are 5 4. Photograph showing siltstone and sandstone of the Bedford Canyon Formation ______________________________.____ 6 5. Photograph showing massive sandstone interbedded with siltstone of the Bedford Canyon Formation .__________________.. 7 6. Photomicrographs of coarse-grained lithic graywacke in the Bedford Canyon Formation .___.___._____________________________ 8 7. Photograph showing redeposited quartzite and siltstone boulders and cobbles in the Santiago Peak Volcanics............ 9 8. Photomicrograph of tuff or volcaniclastic rocks in the Santiago Peak Volcanics c." 40 9. Photograph showing sedimentary features of graded lens in the Holz Shale Member of the Ladd Formation ..__._._..._.... 16 10. Photograph showing contact between the Holz Shale Member of the Ladd Formation and overlying Schultz Ranch Sandstone Member of the Williams Formation ____.._.._..... (A8 11. Photograph showing contact between the Schulz Ranch Sandstone and overlying Pleasants Sandstone Member of the Williams Formation.... a> 20 FIGURE TABLE CONTENTS VII Page 12. Photograph showing the Claymont Clay Bed on Gypsum-Fremont CanyON divide D24 13. Photomicrographs of the Claymont ..... -. :e cence - nen cen cee bn cbdu ret nan ni bani oe eni een cre 25 14. Photomicrographs Of the Claymont C!AY... .-.... ra seres cer 25 15-19. Photographs showing 10. Contact between the Santiago and Silverado FOFMALIOHS- .-..... 29 16. Basal conglomerate of the undifferentiated Sespe and Vaqueros Formations overlying the Santiago Formation ._________ 33 17. Lower part of the undifferentiated Sespe and V@queros FOFMAtIONS 35 18. Basal beds of the habs 38 19. Unconformity between the La Vida Member of the Puente Formation and the undifferentiated Sespe and Vaqueros Formations . n duebnensb reh niks oC anc auss nene cel can anes sabse ela sn d sevice 44 20. Schematic map showing thickness of sandstone in members of the Puente 45 21. Photograph showing member of the Fernando Formation .__________._______________. 54 22. Photograph showing La Habra Formation unconformably overlain by older 59 23. Photograph showing terraces along Silverado and Santiago Creeks... nec 61 TABLES Page I: Petrography of the Bedford Canyon FOrMmaALION . - . . » ~. 22 ZZ} 0.0. ...s cole eee oes eer ee ne onc ne nebo ce saan D8 2. Petrography of the Santiago Peak Volcanics and related iNtrUSiv@ FOCKS 9 9. Petrography of the Ladd FOTmMALIONE--2 -.. ... . ..... : cele cn cee cPe ithe ams 14 d: Petrography Of tho WilaMS FOFMAUION :L. .L. .... --. fe reeded denne nne cen cae co 19 6. Petrography of the BilverAQO-FOTMALON ?-. - >.. . . . | sls ender ee dee Pee ee nn eons 28 6. Petrography of the GAMHAGO FOTMALION: .-... . . - . . ne rebs e eb ione bauer sain Erde nse ee ss ene ces 30 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA GEOLOGY OF THE NORTHERN SANTA ANA MOUNTAINS, CALIFORNIA By J. E. SCHOELLHAMER, J. G. VEDDER, R. F. YERKES, and D. M. KINNEY ABSTRACT The Santa Ana Mountains expose one of the most complete strati- graphic sections in coastal southern California, and much of the sec- tion contains distinctive rocks and diagnostic fossils. The section includes a basement complex of crystalline and semi- crystalline rocks of Mesozoic age, unconformably overlain by as much as 5,200 m of Upper Cretaceous and Cenozoic clastic strata ranging in composition from organic shale to boulder conglomerate. The basement consists of the marine clastic Bedford Canyon Forma: tion of Middle Jurassic age and is perhaps 5,500 m thick; the Upper Jurassic(?) and Lower(?) Cretaceous Santiago Peak Volcanics, 790 m thick; and extensive middle Cretaceous quartz plutonite bodies. The superjacent sedimentary deposits are mostly marine and of Late Cretaceous, Paleocene, Eocene, Miocene, Pliocene, and Pleistocene age. In addition, nonmarine units interfinger with marine, especially just above major unconformities. The northeastern, highest part of the Santa Ana Mountains is a sharply folded anticline, plunging northwest and having a downfaulted, narrow northeast limb and a similarly truncated nose. The downthrow to the north, on the Whittier fault zone, is variable, with an apparent stratigraphic separation of about 900 m. That to the northeast, on the Elsinore fault zone, may be slightly greater. The low western parts of the mountains are underlain by rocks that are only moderately folded, broken by numerous northwest- to north-trending normal faults. A complex, horstlike positive structure extends east-west along lower Santiago Creek. The broad Loma Ridge syncline farther south underlies much of the southern part of the mapped area. At the west edge of the mountains, the post-middle Miocene formations thicken slightly westward toward the subsiding Los Angeles basin, though both thickening and subsidence reverse directions in the subsurface anticlinal Anaheim nose, 5 or 6 km west of the mountains. The geologic map, structure sections, and supporting data show that the geologic record of the northern Santa Ana Mountains characterizes that of the northern Peninsular Ranges, including the San Joaquin Hills to the south and southwest, the Los Angles basin to the west, the Puente Hills to the north, and the Perris Block to the east. Thus, the mountains furnish evidence of regional significance: the boundary between basement and superjacent sedimentary rocks is of Early or middle Cretaceous age; northeastward transgression of Paleocene strata onto successively older units records an early Ter- tiary southwestward tilt of the mountain mass, and northward and eastward onlap of successively younger strata onto the basement sur- face is interptreted as additional evidence of an extensive, persistent early Tertiary peneplain; the tilting of the mountain mass and as- sociated deformation continued to middle Miocene time, when rela- tive depression of the Los Angeles basin began; and continuing de- formation produced pronounced erosional unconformities in upper Miocene, Pliocene, and upper Pleistocene strata. INTRODUCTION The Los Angeles basin is the world's most prolific oil-producing sedimentary basin in relation to its small size. Detailed geologic mapping of the eastern margin of the basin was begun in the northern Santa Ana Mountains by the U. S. Geological Survey in 1948. The objective was to furnish modern large-scale geologic maps of a part of the basin in which many key strati- graphic units are exposed and to prepare definitive lithologic and paleontologic descriptions in order to provide a partial basis for understanding the excep- tional petroleum potential. The mapping program was later expanded to cover the Puente Hills to the north and northwest and the San Joaquin Hills-San Juan Capistrano area to the south. This paper reports on the geology of the northern Santa Ana Mountains. Other parts in this series are Professional Paper 420-A, Geology of the Los Angeles basin-an introduction (Yerkes and others, 1965); 420-B, Geology and oil resources of the eastern Puente Hills area, southern California (Durham and Yerkes, 1964); and 420-C, Geology and oil resources of the western Puente Hills area, southern California (Yerkes, 1972) (fig. 1). The northern Santa Ana Mountains dominate the northern Peninsular Ranges of coastal southern California and form the southeast margin of the Los Angeles basin. The mountains expose the most com- plete section of the late Mesozoic and Cenozoic se- quence that underlies the north part of the Peninsular Ranges physiographic province. Comparisons of the northern Santa Ana Mountains section and its relations to other parts of the basin are given in Chapter A of this Professional Paper (Yerkes and others, 1965). This report describes the geology of the Black Star and Orange 7.5-minute quadrangles and the north halves of the El Toro and Tustin 7.5-minute quadran- gles (fig. 1). Fieldwork was done in 1948-53; revisions of the northeast part of the Black Star quadrangle were made in 1954 and 1976. A draft of the report was written in 1955 and first re- vised in 1959-60, using data from surface exposures and from wells drilled before 1959. Some later data collected up to June 1976 have been made a part of the report during final revision. The list of wells includes D1 2 only those used in preparation of this report, and the nomenclature of the operators is that in use in 1958. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA ACKNOWLEDGMENTS It is a pleasure to acknowledge the scientific con- tributions of the U. S. Geological Survey colleagues Patsy B. Smith, M. C. Israelsky, G. Edward Lewis, T. H. McCulloh, Ellen J. Moore, W. P. Popenoe, L. G. Schultz, Ralph Stewart, A. O. Woodford, and W. P. Woodring during the course of the field and laboratory work leading to completion of this study. The final manuscript was improved as a result of suggestions made during critical reviews by T. H. McCulloh and George W. Moore. We single out for special mention the contributions of A. O0. Woodford, who participated 118° 30' 15) 118°00' # 45" 117° 3730" T T I vAN NUYS BURBANK BEVERLY HOLLYWOOD HILLS < a 2 Ps o H S0 | --B VENICE INGLEWOOD WHITTIER LA HABRA | YORBA LINDA] PRADO DAM McCulloh, T. H., 1957, Map GP-149 Yerkes, R. F., 1973, Durham, D. L., and Yerkes, R.F., Prof. Paper 420-C 1964, Prof. Paper 420-B REDONDO TORRANCE LONG BEACH ORANGE BLACK STAR BEACH N CANYON $ ~N~XAN Schoellhamer, J. E., and others, \1954, Map OM-154 f/Fj H Area of Fig.3 88:7 TNCs. a aye K NEWPORT TUSTIN EL TORO BFACH Vedder, J. G., and others, 1957, 122" 120° 118° 114" Map OM-193 I ~ [> Vedder, J. G., 1975, QQJ NEVAD Open-File 75-552 L 36° 2 o ~ #} ( 1; LAGUNA SAN JUAN SantaJ ¢ a BEACH CAPISTRANO Barbara) Los Angeles g o o 34° § basin . 3+ Ap ei k San Dieg 5s 35 o MIEXICO 30' 0 100 - 200 MILES DANA POINT 0 5 10 15 20 25 KILOMETERS L 1 | | 1 | I I I I o 5 10 15 MILES | | 1 4 1 FIGURE 1.- Outline map of the Los Angeles basin. Area mapped for this investigation is patterned by diagonal lines; names of pertinent 7.5- minute quadrangles are shown. Entire area included in an introduction to the structural and stratigraphic history of the Los Angeles basin (Yerkes and others, 1965). GEOLOGY OF THE SANTA ANA MOUNTAINS D3 in many aspects of the research during its progress and who, through innumumerable discussions, was in- volved in the generation of many of the concepts pre- sented here. Without the help of Ellen J. Moore and Rose M. Trombley in preparing the text for editing, the report in its present form probably would not have been completed. The subsurface data used in compiling parts of this report were furnished by oil companies and consulting geologists active in the Los Angeles area; their cooper- ation and help is gratefully acknowledged. These data and discussions with these geologists provided signifi- cant stratigraphic and structural information unob- tainable elsewhere. The California Division of Oil and Gas furnished data on some of the older wells drilled in the area. All of these data were used in compiling the structure sections (pls. 2 and 3). In the 1976 revision especially important supplementary information was furnished by L. J. Simon, F. R. Goodban, and J. M. Gibson of Texaco, Inc., R. A. Davis of Union Oil Com- pany, and M. J. Castro of Casex. The cooperation of the many landowners who granted permission to enter their property is also gratefully acknowledged. Special thanks are due Mr. W. B. Hellis, formerly manager of the Irvine Ranch, for permission to enter this ranch, which covers nearly 50 percent of the mapped area. The California Division of Forestry and the U. S. Forest Service furnished access to many of the fire roads in parts of the area. During the fall and winter of 1949-50, J. F. Richmond prepared a geologic report on a 38-km" area along Burruel Ridge (fig.2). His report was published by the California Di- vision of Mines (Richmond, 1952), and the map pre- sented here for that area is essentially the same as his. Field assistance was furnished by A. E. Altinli, visiting from Turkey in 1948, and nomenclatural revisions of Eocene mollusks by C. R. Givens, Nicholls State Uni- versity, Louisiana. William Otto, formerly preparator at the California Institute of Technology, guided the authors to a fossil vertebrate locality in the undifferen- tiated Sespe and Vaqueros Formations south of Bolero Lookout and assisted in collecting the remaining avail- able material. T. A. Downs of the Los Angeles County Museum arranged to loan material previously collected from this locality. C. H. Gray, Jr., of the California Di- vision of Mines and Geology , assisted in mapping the northeast part of the area. After the publication of the preliminary map (Schoellhamer and others, 1954) Donald L. Lamar, then a Fellow at the University of California at Los Angeles, mapped parts of the north- east corner of the Black Star Canyon quadrangle and the adjoining area to the east; his geologic information necessitated some map revisions in this area. JURASSIC SYSTEM MIDDLE JURASSIC SERIES BEDFORD CANYON FORMATION The oldest exposed rock unit in the northern Santa Ana Mountains is the Bedford Canyon Formation named by Larsen (1948) for exposures in Bedford Canyon. The Bedford Canyon is composed chiefly of slightly metamorphosed, locally slaty siltstone and graywacke, with minor amounts of pebble conglomer- ate and limestone (fig. 3). The type locality is in Bed- ford Canyon, 6 km east of the map area. The Bedford Canyon extends west and northwest from its type into upper Silverado and Ladd Canyons (pl. 1) and occurs in the subsurface at least as far as the west edge of the northern Santa Ana Mountains (Texas Co. well, Irvine NCT-2 No. 1, and other wells south of the map area). The base of the formation is not exposed. South of Oak Flat the Bedford Canyon Formation is overlain uncon- formably, with as much as a 90° discordance, by the Santiago Peak Volcanics; elsewhere it is intruded by quartz plutonite and gabbro of the Southern California batholith (Larsen, 1948). The prevailing dip is compli- cated by minor folds and shear zones (fig. 4). In Silverado Canyon, a traverse suggests a thickness of 5,500 m. The actual thickness may be much less, as indicated by isoclinal folding (fig. 5) and possible over- turning (Buckley and others, 1975, p. 299-300). Esti- mates along the traverse suggest proportions of 59 percent siltstone, 40 percent graywacke, and 1 percent conglomerate and limestone. The graywacke is gray and made up of angular grains up to 2 mm in diameter that are approximately one- third quartz grains, one-third rock fragments, and one-third matrix (fig. 6; table 1). The beds are com- monly a meter or less thick, separated by metasiltstone layers 5 to 10 ecm thick, and are seamed with quartz veinlets. The siltstone breaks into small blocks bounded by the bedding planes, slaty cleavage, and joints perpendicu- lar to the bedding. The rock is reddish gray to bluish black and composed of particles whose maximum size ranges from 0.005 to 0.1 mm in the samples studied. Slivers of muscovite mark irregular layers of stratifica- tion (table 1). At places thin lenses of resistant pebble conglomer- ate are sporadically interbedded with the sandstone and siltstone. One pebble bed in upper (eastern) Sil- verado Canyon is 8 m thick. The pebbles are as much as 3 cm in diameter, subrounded to rounded, and polished. They are light- to dark-gray quartzite, chert, and indurated argillite. The matrix is recrystallized ar- D4 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA gillaceous material that weathers brown. stone bodies of the Bedford Canyon Formation have Limestone outcrops east of the map area yield fossils | been resedimented, and the allochthonous fossils in diagnostic of Callovian (Middle Jurassic) age (Silber- | them set a maximum age limit (Moran, 1976, p. ling and others, 1961; Imlay, 1963). Some of the lime- | 2040-2041). 0 # re - 117 5230 45" 117°37'30" 33°52'30" Sierra \ Peak Orange / E1 Modeno Panorama Heights te Peters Canyon Reservoir ~ AWMIFH4 1 HOIMIN fr f 4 ck anvo?~ may)"; _Witham® $5": Hard \_ Modejeska I *X f t fx acy »20o \SANTIAGO ~ RUCKR TRAIRD, > Qa—mbert 55 Renrvo% 33°39'04" 5 6 kiLometTEeRs 0 1 2 3 MILES FIGURE 2.- Generalized physiographic map of the northern Santa Ana Mountains, showing geographic names. JURASSIC (?) QUATER: 'eare euy usoyjJ0u ay; Jo uor}oas atydeaSne.4s poztfeJauan -'g dHNOIY JURASSIC AND CRETACEOUS CRETACEOUS TERTIARY NARY SYSTEM Miocene Pliocene _ [Pleistocene miadie Jurassic one ii iain thus | - upper Cretsssous hame Pains | "ana "| Series Middle Upper Lower l Upper Holocene Santiago Pesk Mig: Sespe and Topanga Bfi'::r:£f::°n Volcanics and Fokfifion Falmxro'n Vaqueros Forma- Puente Formation 2:41:23; FL:’::3;'" Formation related intrusive rocks T Fms., undiff. tion Baker Holz Schulz Sycamore Canyon Shale Ranch Soaue! ..V°'E‘ Canyon Lower “Um," Member Cgl. Mbr. | Member (Ss. Mbr. Mor. Maximum 5,000 + 1990 + 425 730 290 915 690 885 610 760 670 915 800 Thickness, = in meters $» >>> § }% 85 94> adul $») Y* *» *> N yy Db > > 55.5.3 5 % f ND Nb hb A NDD 5 R fbb b> > 5 DS 5 > 5 80° $33 b> b 333 YD we ~* 33> 333 S> 3 S $i > $3 > }¢ o 8 mesi dre A ay % >> I| AC. [~ /’\\/\\/~\//l/\/‘ A3 5 51% >> Y eXxNMi Mab > >>> >> > > > AAV lp ad hud bar A A I + /l|/’/\’\/\/\l’\,\/\/l->>>>>>>>> es | a HA NAMA tak atrryg >> ¢ » 33 »I tmrig:l I $ Maximum 173 230 490 150 135 | Thickness, in meters Oso Member Member so“‘""';g:::::|:’;’nh°mh Trabuco El Modeno | Monterey Capistrano Niguel Alluvial Forrzrlon {not exposed in map sree) Formation Volcanics Shale Formation Formation deposits unit ejeos jeonuea 0 -- 0 000€ -_ oo01 -- 0008 SH31.3W 0006 -I 1334 bs 3 F a G ey99m42,8 pug pesoudsowrmew Ajrybiis a & & < 'euorspues euorspues Aris 'euosspueg 'ejeys 10 auorsAe|p $3901 proyusig §$.2 > > > > y m B m c x # ho 1 .: & F 2 2 > § ~ 3 0 & SNVLNAON VNV V.LNVS HHL 40 ADOTOHD SU D6 JURASSIC(?) AND CRETACEOUS SYSTEMS UPPER JURASSIC(?) AND LOWER(?) CRETACEOUS SERIES SANTIAGO PEAK VOLCANICS AND RELATED INTRUSIVE ROCKS The oldest igneous rocks exposed in the northern Santa Ana Mountains consist of at least 790 m of mildly metamorphosed extrusive volcanic rocks. An- desitic flows and flow breccia, greenstone, dacitic flows, volcanic "slate chip" breccia, and minor bedded tuff are associated with quartz-bearing and other in- trusive rocks. Larsen (1948, p. 23) named this domi- nantly extrusive sequence the Santiago Peak Volcanics after their representative exposures on Santiago Peak, 10 km southeast of the map area. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA These volcanic rocks rest with angular discordance upon a surface of irregular relief cut across the Bedford Canyon Formation. They are discontinuous because of dismemberment by the Southern California batholith and because of their unconformable cover of younger sedimentary rocks. East of Black Star Canyon, they form a westward-dipping band 0.5 to 1.5 km wide. They extend around the northern end of the Santa Ana Mountains and are exposed along the northeastern flank of the mountains (Gray, 1961). The distribution of the volcanic rocks southeast of the map area (Lar- sen, 1948, p. 1) shows that they are mostly remnants of a thick and once-widespread sheet. The Santiago Peak Volcanics underlies approximately 15 km" of the map area. Its western limit is unknown, but the volcanic FicurE 4.- Siltstone and sandstone of the Bedford Canyon Formation in a cut on Bedford Peak Truck Trail in Alberhill quadrangle, directly east of map area. Note hammer at lower left. GEOLOGY OF THE SANTA ANA MOUNTAINS rocks extend westward from the outcrop area for sev- eral kilometers beneath younger sediments. The Mor- ton and Sons well, El Toro No. 14-1, 3 km north of the town of El Toro and about 3 km directly south of the map area, cored hard, dense metavoleanic rocks simi- lar to those of the Santiago Peak Volcanics at 1,986 m (Schoellhamer and Vedder, 1975). The formation is probably about 790 m thick in and just north of Silverado Canyon, though only the basal 180 m is well exposed. Several rock types, not differentiated on the geologic map, have been recognized. Throughout the map area the lower part of the Santiago Peak Volcanics is made up of rock types which are distinctive and relatively re- sistant to weathering. These basal rocks consist of vol- D7 canic "slate chip" breccia and an overlying bone-white dacite(?) flow. Succeeding them is a thick, massive section consisting of a repetitious sequence of altered andesite flows, flow breccia, and agglomerate. In the Sierra Peak area near the northern limit of the forma- tion, one or more large bodies of intrusive rock are present. These rocks are quartz bearing and porphy- ritic, and locally tourmalinization is conspicuous. Numerous small dikes and sills of quartz-free andesitic rocks intrude the volcanic rocks throughout the map area. VOLCANIC "SLATE CHIP" BRECCIA Almost everywhere, the basal 15 m or so of the San- tiago Peak Volcanics consist of breccia. In Silverado FicurE 5.- Massive sandstone interbedded with darker laminated fractured siltstone of the Bedford Canyon Formation, showing an isoclinal fold cut by shear (just above hammer handle) in roadcut on Bedford Peak Truck Trail. D8 Canyon, 700 m east of its junction with Ladd Canyon, the lowest 1.5 m of this breccia is largely made up of boulders and cobbles derived from the underlying Bed- ford Canyon Formation imbedded in a silicified, sandy, altered igneous matrix (fig. 7). The boulder-cobble breccia grades upward into the "slate chip" breccia typ- ical of the lowest part of the formation. Here it is 15 m thick and is made up of 50 percent loosely packed fragments of indurated siltstone and graywacke averag- ing 5 mm in diameter in a completely silicified igneous matrix (table 2). FIGURE 6.- Photomicrographs of coarse-grained lithic graywacke in the Bedford Canyon Formation; angular quartz grains in chlorite matrix. A, Plane light; B, Crossed nicols. TABLE 1.-Petrography of the Bedford Canyon Formation Volume Rock type Composition Percent Comments Graywacke. Rock fragments ._...... 43 Ece 20 Sodic plagioclase . Chlorite...... Muscovite. Mate Matrix .. ..30 _ Chloritic, micaceous, and clayey. Siltstone. Quie. c. 35-60 _ Matrix seems to be sericite, chlorite, and clay minerals in a silicic cement. Muscovite .......... 10-15 Rock fragments .... 25-60 _ Feldspar is rare. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA DACITE(®) FLOW Overlying the volcanic "slate chip" breccia is a dis- tinctive, hard, bone-white, deeply altered and silicified dacite(?) flow with large glassy quartz phenocrysts. In Silverado Canyon this unit is approximately 10 m thick; elsewhere it reaches 15 m in thickness and com- monly forms rugged, angular outcrops that disinteg- rate into white talus slopes. Larsen (1948, p. 25) as well as Bellemin and Merriam (1958, p. 217) termed this rock a rhyolite. On the basis of microsopic analysis it is believed to be of dacitic composition; possibly it is a silicified dacitic tuff. TUFF Thoroughly altered bedded tuff was sampled from two localities near the base of the Santiago Peak Volcanics. One locality is near Williams Canyon in the southeast part of the map area, the other on the Main Divide motorway 8.9 km farther north. Both bodies of tuff are contaminated with detrital rock and quartz grains; each contains plagioclase in microlites and larger fragments (fig.8). The tuff beds are soft, crumbly and easily eroded. ANDESITE FLOWS AND FLOW BRECCIAS Andesite flows and flow breccias are the commonest and most wide-spread rocks in the Santiago Peak Vol- canics. These rocks are best developed in the region drained by Silverado and Ladd Canyons and are not prominent in other parts of the map area. In Silverado Canyon the white dacite(?) flow is overlain by more than 60 m of andesitic breccia containing chips and pebbles of redeposited volcanic and sedimentary rocks. In Ladd Canyon the breccia is extensive and forms steep canyon walls at least a hundred meters high. Elsewhere, the dacite(?) flow is overlain by a repeti- tious sequence of deeply altered grayish-green or red- dish to lavender porphyritic andesite flows, locally brecciated or agglomeratic. Fresh unweathered rock is commonly light to dark greenish gray. Differential weathering of the brecciated and agglomeratic rocks produces rough, nodular surfaces. Other structural features such as flow banding and vesicularity are dis- cernible rarely and only on weathered surfaces. Surface staining by iron oxides is thought to be derived from pyrite. Plagioclase phenocrysts in the andesite average 0.3 mm in length, with a 4 mm maximum; they commonly range from Anss to An ss and typically are partly altered to albite, calcite, chlorite, quartz, or illite. Augite seems to have been a common original mineral that was altered to chlorite. In one sample, 6 percent is hornblende after augite(?) and 18 percent chlorite after hornblende or augite. More commonly, however, the andesite is more complexly altered to greenstone (table 2). GEOLOGY OF THE SANTA ANA MOUNTAINS D9 DACITE PORPHYRY the feldspar phenocrysts locally gives the rock a light- colored chalky appearance. Many small dikes and sills of altered quartz-free an- desitic rocks cut both the Santiago Peak Volcanics and the underlying Bedford Canyon Formation. In the At least one large mass of dark-gray-green quartz- bearing porphyritic rock intrudes the Santiago Peak Volcanics in the area north and east of Sierra Peak. This body, called quartz porphyry Larsen (1948, p. 27), may be related to his Temescal Wash Quartz Latite | Tass 2.-Petrography of the Santiago Peak Volcanics and related in- Porphyry (Larsen, 1948, pp. 36-39). The composition trusive rocks of the intrusion near Sierra Peak, based on micromet- Volume . P + nat + Rock t Composition Comments ric analysis, is clearly dacitic, and the rock is best | _ Pes percent e called a dacite porphyry. The rock is the most resistant Matrix of - Plagioclase... 40 _ Calcitized and silicified in pseudomorphic P f % volcanic ai to 1 ' f of the igneous rocks in the area, and the larger bodies | "slate Magnetite or ilmenite .20 1;me ( prams. % r chip" Cece cs cece ce 10 trained; as clasti ins. form bold, angular outcrops with nearly vertical con- breccia. Microcrystalline 30 Cotilpvfsed thqausafifrlil:gsioclase microlites, tacts groundmass. muscovite, chlorite, and clay minerals. a ; § R Green- Plagioclase.............. 20 _ Altered. Exposures of this dacite porphyry are generally light |.: ones ig i 1 1 Pyrite jm A 5 t_0 dark yeHOWISh brown in COlor' FrESh SpeCImens are Groundmass ............ 45 - Includes chlorite, epidote, quartz, feldspar, light to dark greenish gray, hard and dense, and por- illite, and actinolite. +44 s P Altered Me Ve. 20 Embayed and hyritic. phyritic, consisting of closely packed quartz and dadite Slik A5 _ In % + P por- feldspar pheno CI'yStS in a much finer gralned phyry. Paledolivegreen, in small rosettes of needles groundmass. The phencrysts of quartz and plaglOCIaSe Silicified groundmass .50 ngrugziglaféldspar; average grain diameter average 1 mm and are up to 8 mm long. Alteration of FIGURE 7.- Redeposited quartzite and siltstone boulders and cobbles in the basal part of the Santiago Peak Volcanics, south wall of Silverado Canyon. D10 Bedford Canyon Formation most of the intrusive bodies occur near the contact with the overlying San- tiago Peak Volcanics and are probably associated with old faults. No notable differences are apparent between the dikes in the two formations. Small chips charac- teristic of the Bedford Canyon are included in the in- trusive bodies. Both the quartz-free and the quartz-bearing intrusive rocks are similar texturally and mineralogically to the Santiago Peak Volcanics and display much the same alteration and recrystallization. Larsen (1948, p. 27) shows that these intrusive rocks are themselves in- truded by the batholith. Presumably these pre- batholithic rocks are genetically related to and in part contemporaneous with the Santiago Peak Volcanics. ALTERATION AND METAMORPHISM Mild metamorphism, deuteric alteration tourmalini- zation, and epidotization have had varying effects upon the Santiago Peak Volcanics and the related intrusive rocks throughout the area. Widespread mild metamorphism of the volcanic rocks and their related intrusive rocks has masked the deuteric alterations, such as chloritization and cavity "m A Z4 | tA . a ch da ¥, t (%. amod‘ioIv-unn mam nnd‘chl "tule, .~ ~ f *X" za fix‘fl‘v‘ _.: Aae." oad & 4. ials " Me P ias * . 4 FIGURE 8.- Photomicrograph of tuff or volcaniclastic rocks in the Santiago Peak Volcanics, showing numerous angular fragments of volcanic and sedimentary rocks. From bed 1+ m thick in Wil- liams Canyon. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA filling, that may have accompanied their deposition. Chief among the effects of metamorphism is the re- placement of the feldspar phenocrysts by albite, quartz, chlorite, epidote, and calcite, or illite and cal- cite. These replacements were accompanied by recrys- tallization of the groundmass to microcrystalline mosaics of quartz, albite, and the characteristic prochlorite. The ferromagnesian minerals commonly are completely replaced, often pseudomorphically, by chlorite or chlorite and calcite. Pseudomorphs of hornblende after augite, characteristic of greenstone of more advanced grade, are uncommon in the Santiago Peak rocks of this area. IImenite was identified with certainty in only a few samples, but pyrite and leucoxene are present in minor amounts. Metacrystal- line quartz is widespread in the groundmass of many of the rocks, and occasionally it is euhedral. Mantles of secondary quartz typically enclose the phenocrysts, and veinlets of calcite, epidote, and clinozoisite are com- mon in the more highly altered rocks. TOURMALINIZATION A broad belt of tourmalinized rocks occurs in the quartz-bearing intrusive rocks southwest, west, and northwest of Sierra Peak. Three widely separated sam- ples were collected along the east boundary of see. 1, T. 3 S., R. 8 W. Two samples, the most extensively al- tered, contain 39 and 10 percent tourmaline, and the latter contains several fragments of siltstone that have been extensively tourmalinized along with the host rock. In this rock the replacement of feldspar by tour- maline is incomplete (table 2). In the other sample the feldspar apparently has been completely replaced, and the grayish-green tourmaline occurs in radial patches of needles that commonly pierce the intimately sutured quartz grains that make up the groundmass. Primary subhedral phenocrysts of quartz as large as 1.5 mm in maximum dimension are still preserved. The grain size of the groundmass quartz averages 0.07 mm in maximum dimension. Relict plagioclase phenocrysts indicate that the completely tourmalinized rock rep- resented by this sample probably was derived from the quartz- bearing intrusive rock of the Sierra Peak area. A sample from the quartz-free porphyritic andesite flow rock on the ridge west of the head of Wardlow Canyon (SE'/« sec. 6, T. 4 S., R. 7 W.) contains 1.5 percent tourmaline. EPIDOTIZATION A small zone of extensively epidotized volcanic rocks is present in the roadcuts of the Corona Skyline Drive where it descends the northeastern flank of the Santa Ana Mountains. The andesitic host rock in this zone GEOLOGY OF THE SANTA ANA MOUNTAINS contains from 5 to 90 percent epidote, commonly as discrete grains in a partly to wholly recrystallized groundmass, and occasionally as sporadic aggregates of grains associated with calcite in altered phenocrysts or as small veinlets with clinozoisite and calcite. AGE AND CORRELATION Fossils have not been found in the Santiago Peak Volcanics within the map area. The formation is younger than the Callovian (Middle Jurassic) part of the Bedford Canyon Formation and older than the Turonian (Late Cretaceous) beds at the base of the un- conformably overlying Trabuco and Ladd Formations. Apparent radiometric ages from the Santiago Peak Volcanics in the Silverado Canyon area are 131%2.6, 106+2.3, and 85 +2 million years (Colburn, 1973, p. 58) and 155%15.5 million years at Santiago Peak (Bushee and others, 1963, p. 803-804). Unconforma- bly overlying Turonian beds in Silverado Canyon imply that the 85 m.y. date is too young. The stratigraphic re- lations in the northern Santa Ana Mountains suggest an age of Late(?) and Early( ?) Cretaceous. The formation resembles parts of the andesite: bearing Alisitos Formation of Baja California, which is of Aptian and Albian (Early Cretaceous) age according to Allison (1955) and Gastil and others (1975). Slate and argillite interbedded with rocks assigned by Fife and others (1967, p. 300-303) to the Santiago Peak Volcanics in the San Diego area contain Buchia piochii, which is diagnostic of the latest Jurassic (Tithonian); hence this fossiliferous sequence is older than the Alisitos Formation. The type Santiago Peak Volcanics probably correlates in part with both the Eugenia Formation in Baja California, which ranges from Tithonian to probable Valanginian (Jones and others, 1976), and with the Espada Formation of Dibblee (1950; 1966) in the Santa ¥nez Mountains and southern Coast Ranges. Andesite dikes that intrude the Eugenia Formation have yielded a K-Ar age of 124.6 +3.2 million years (Minch and others, 1976, p. 146-147). CRETACEOUS SYSTEM UPPER CRETACEOUS SERIES Cretaceous rocks of the Santa Ana Mountains were first reported by the California Geological Survey (Whitney, 1865), although paleontologic evidence for their age was not published for more than 20 years (Cooper, 1888; Goodyear, 1888; Bowers, 1890). Pac- kard (in Dickerson, 1914, p. 262-263) assigned six lithologic units in the Santa Ana Mountains to the Upper Cretaceous Chico Formation, the type locality of Dil which is in northern California. Later the uppermost of these units was found to be Paleocene in age. Packard (1916, p. 140-141) proposed the name Trabuco For- mation for the lowest unit, which is nonfossiliferous. Popenoe (1937, p. 380) grouped the remaining four units into two formations, the Ladd Formation and the Williams Formation, each made up of a coarse-grained lower member and a finer grained upper member. The names were modified slightly by Popence (1942, p. 170-175), by Woodring and Popenoe (1945), and by Schoellhamer and others (1954), in part to distinguish them from similar names used earlier elsewhere. The resulting terms are as follows, from the top down: Williams Formation Pleasants Sandstone Member Schulz Ranch Sandstone Member Ladd Formation Holz Shale Member Baker Canyon Conglomerate Member Trabuco Formation TRABUCO FORMATION A relatively thin discontinuous sequence of red and maroon clayey conglomerate and sandstone forms the basal unit of the unmetamorphosed sedimentary strata at most places in the northwestern Santa Ana Moun- tains. The type section of this sequence, named the Trabuco Formation by Packard (1916, p. 140-141), is in Harding Canyon near the village of Modjeska secs. 28 and 29, T. 5 S., R. 7 W., at the southeast corner of the map area. The Trabuco Formation is exposed in a narrow belt along the eastern edge of the El Toro and Black Star Canyon quadrangles, from the vicinity of Williams Canyon northward to the divide between Baker Canyon and Black Star Creek. At this point it grades laterally into the lower part of the Baker Canyon Conglomerate Member of the Ladd Formation, and it cannot be rec- ognized or traced farther north. Gray (1961) assigned red conglomerate to the Trabuco Formation on the northeast slopes of the Santa Ana Mountains from near the mouth of Hagador Canyon northwestward to Mabey Canyon. These outcrops are bounded on the southwest by the Elsinore fault. The westward extent of the Trabuco Formation be- neath the cover of younger sedimentary rocks is known only from fragmentary information. About a hundred meters of the formation is present in the J. J. Stephens well, Susie M-1, in Silverado Canyon 1,400 m west of the nearest outcrop of the Trabuco (pl. 1). The Texas Co. well, Irvine (NCT-2) No. 1, in Little Joaquin Valley 10 km east of Santa Ana, penetrated rocks assigned to the Bedford Canyon Formation without drilling through the Trabuco Formation. Apparently it is absent D12 in the West American Oil Co. well, Irvine No. 1, 2 km farther west, near the Irvine Ranch headquarters, al- though the geologic interpretations for this well are somewhat doubtful. Other wells in the area have not been drilled deep enough to penetrate the Trabuco Formation. The outcrop pattern and the scanty subsur- face results suggest that the Trabuco may be limited in areal extent to the southeastern part of the map area. The Trabuco Formation is relatively unconsolidated, deeply weathered and easily eroded. Badland topog- raphy is developed locally. Gentle slopes are commonly covered by a moderate growth of brush, and the soil and outcrops show the brown, red, and maroon colors characteristic of the formation. STRATIGRAPHY AND LITHOLOGY The Trabuco Formation rests with profound angular unconformity on both the Santiago Peak Volcanics and the Bedford Canyon Formation. In the southern three- quarters of the outcrop area, it is underlain by the vol- canic unit; in the northern quarter, it rests directly on the Bedford Canyon Formation, the volcanic rocks ap- parently having been removed by erosion before depos- ition of the Trabuco. The Trabuco Formation consists mainly of reddish- brown to maroon conglomerate, sandstone, and minor amounts of clayey siltstone. Crossbedding is present at some places in the sandstone and conglomerate. The conglomerate clasts are generally subangular to sub- rounded measuring as much as about 1 m and averag- ing between 7 and 15 cm. Some clasts are so deeply weathered that they crumble when touched. Four rec- ognizable rock types are common as clasts in the con- glomerate. These include (1) coarse-grained light- colored granitic and granodioritic types, derived from plutonic rocks of the Southern California batholith; (2) greenish-gray volcanic rocks similar to the Santiago Peak Volcanics; (3) hard gray dacite or quartz latite porphyry resembling that which intrudes the Santiago Peak Volcanics near Sierra Peak; and (4) blocks and chips of siltstone and sandstone derived from the Bed- ford Canyon Formation. Other rock types present in the conglomerate include quartzite, hard fine-grained vol- canic rocks of many types, and chert. The conglomer- ate matrix is a poorly sorted clayey feldspathic sandstone containing dark-colored rock fragments and crinkly flakes of biotite bleached to various shades of greenish black to golden brown. Popence (19141; p: 743) studied outcrops of the Trabuco Formation and concluded that volcanic and sedimentary rocks pre- sumably derived from the Santiago Peak Volcanics and Bedford Canyon Formation make up the major part of the conglomerate. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA In addition to conglomerate, the Trabuco Formation includes conglomeratic sandstone and sandstone simi- lar to the matrix of the conglomerate. Most sandstone beds have a reddish-brown clayey micaceous matrix that has a waxy luster on fresh surfaces. The formation is locally gray or white, and some sandstone beds con- tain local thin light-gray streaks. On the divide be- tween Williams and Silverado Canyons, approximately 30 m of the basal part of the Trabuco Formation con- sists of a whitish conglomerate composed of sub- rounded to rounded cobbles and boulders with a maximum dimension of about 1 m. The main clast types are the same as those in other exposures of Trabuco conglomerate. This whitish conglomerate ap- parently grades upward and laterally into the typical red strata of the Trabuco. The thickness of the Trabuco Formation ranges from about 85 m just south of Silverado Creek to zero on the ridge between Ladd and Baker Canyons. It increases abruptly to a maximum of 173 m in Baker Canyon then decreases northward to about 115 m at structure sec- tion U-V (pl. 3) and terminates in Black Star Canyon where the Trabuco intertongues with the Baker Canyon Conglomerate Member of the Ladd Formation. A meas- ured section across the entire formation in Baker Can- yon is 40 m thick, almost all reddish conglomerate. Although the Trabuco Formation lacks fossils, its in- terfingering with the fossiliferous Baker Canyon Con- glomerate Member establishes its early Late Creta- ceous age. Its clayey red matrix and lack of fossils in- dicate nonmarine deposition. Conglomerate similar to that of the Trabuco Forma- tion occurs farther north and south in this part of California. In the Santa Monica Mountains northwest of Los Angeles, a red conglomerate unit is present at the base of the Upper Cretaceous section (Hoots, 1931, p. 90; Colburn and Fritsche, 1973). It has been reported to be locally 380 m thick (Durrell, 1954, map sheet 8). South of the Santa Ana Mountains conglom- erate of the Trabuco Formation or conglomerate some- what similar to that of the Trabuco is present in many places as far south as San Diego and beyond (Hertlein and Grant, 1939, p. 75-76); Woodford and others, 1968, p. 1469; Peterson, 1971; Nordstrom, 1970; Ken- nedy and Moore, 1971, p. 711). LADD FORMATION Popenoe (1942, p. 170) designated the type locality of the Ladd Formation as the region immediately west of the mouth of Ladd Canyon and divided the forma- tion into the Baker Canyon and Holz Shale Members with a combined maximum thickness of approximately 520 m. Northeast of Fresno Canyon in the northeastern GEOLOGY OF THE SANTA ANA MOUNTAINS part the map area, the formation consists of more than 900 m of interbedded sandstone, siltstone, and con- glomerate; here the members cannot be differentiated. BAKER CANYON CONGLOMERATE MEMBER The Baker Canyon Conglomerate Member of the Ladd Formation crops out near the east edge of the map area in an almost continuous north-trending strip 100 to 2,000 m wide with the dip to the west. Its type locality is in Baker Canyon, north of Silverado Canyon (Popenoe, 1942). North of Sierra Peak it is present in the fault blocks on the north edge of the Santa Ana Mountains and continues, almost without interruption, along the narrow, downfaulted northeast flank of the mountains into the Elsinore trough (Gray, 1961; Gaede, 1969). In the northwestern part of the Santa Ana Mountains, it crops out in a small upfaulted block, possibly a faulted anticline, at the mouth of Blind Can- yon on the north side of Santiago Creek between Irvine Park and Irvine Lake. STRATIGRAPHY AND LITHOLOGY The lower part of the Baker Canyon Conglomerate Member consists of a sequence of greenish-gray con- glomerate beds in which many of the clasts are as much as 2 m in diameter. The pebbles, cobbles, and boulders are mostly well-rounded and are composed of either light-gray quartz plutonic rocks like those in the basement complex or light- and dark-gray siliceous volcanic and hypabyssal rocks. The siliceous rocks were derived largely from the Santiago Peak Volcanics and related intrusions but also include metatuff somewhat similar to that which is abundant in overlying Paleogene conglomerate. The conglomerate matrix is sandstone that is composed mainly of quartz and feldspar and contains biotite flakes and rock frag- ments. Sandstone beds are rather rare, occurring chiefly high in this lower part of the sequence. Thin beds of red silty sandstone are locally present near the base. North of this area between Baker and Black Star Canyons, where the Trabuco Formation pinches out, the lower part of the member is the lowest unit in the superjacent sequence. For a short stretch near Oak Flat, both the Trabuco Formation and the Baker Can- yon Conglomerate Member are missing. On the crest of the mountains, north of Oak Flat, boulders in the lower part of the member are exceptionally large; the biggest observed is a slab of coarse biotite granodiorite 11X10x2 m. Here the member rests directly on the basement. The upper part of the Baker Canyon Conglomerate Member, throughout the map area, is characterized by its yellow-brown color and smaller clast size. Most of D13 the beds are composed of conglomeratic sandstone. Some beds are finely laminated sandstone; less com- mon beds of pebble and cobble conglomerate are as much as 3 m thick. Sandstone beds are locally carbo- nate cemented and contain abundant mollusk shells. North of Oak Flat the easily eroded upper part of the member is well exposed only in the south wall of Santa Ana Canyon. Here the upper 35 percent of the section is coarse gritty feldspathic sandstone interbedded with silty layers a few centimeters thick that contain many black carbonaceous fragments. The contact with the overlying Holz Shale Member seems to be gradational, as thin dark-gray to black siltstone and sandy siltstone layers are interbedded with the coarser strata just below the contact. The lower part of the Baker Canyon Conglomerate Member is possibly of nonmarine origin in the area south of Black Star Canyon. Lithologically the Baker Canyon is similar to the underlying Trabuco Forma- tion, and the contact is gradational and in places inter- tonguing. In the vicinity of Black Star Canyon, the red- dish Trabuco Formation is stratigraphically equivalent to at least the lower part of the greenish-gray Baker Canyon Conglomerate Member. The colors are mottled and irregular, are not confined by bedding, and are therefore not depositional features. Thick-shelled marine pelecypods such as Trigonarca, Cucullaea, Spondylus, and Pterotrigonia, which indicate a shallow marine environment, are common in the uppermost part of the conglomeratic facies and in the sandstone at the top of the member. Popenoe (1941, p. 738-752) concluded that the Baker Canyon Conglomerate Member was entirely marine in origin and that the Trabuco Formation was a separate and distinct stratigraphic unit. However, the gradation and intertonguing of the two units indicate a more complex history involving both original deposi- tional environments and diagenetic changes. Conditions of deposition were somewhat different in the Oak Flat-Sierra Peak area, where the Baker Canyon Conglomerate Member is very thin and locally absent, and the basal nonmarine beds are missing. Marine fos- sils occur in thin lenses of gray siltstone a meter or so above the unconformable contact with the underlying Santiago Peak Volcanics. These marine strata are over- lain by the coarsest greenish-gray conglomerate in the area. The section of the Baker Canyon Conglomerate Member exposed along the Riverside Freeway shows the characteristic two-fold lithologic division. The lower part is unfossiliferous, coarse, greenish-gray, very poorly bedded conglomerate that is believed to be nonmarine. The upper part is lighter colored, better stratified, and better sorted sandstone and conglomer- D14 ate presumed to be marine, although no fossils were found in it. The Baker Canyon Conglomerate Member ranges be- tween zero and 425 m in thickness. Just north of Oak Flat, 5 km south of the northeast corner of the map area, the member is missing, and the Holz Shale Member lies directly on the eroded surface of intrusive rocks of the Santiago Peak Volcanics. The Baker Can- yon is estimated to be 425 m thick in its northernmost outcrop, along Santa Ana Canyon. It has a measured thickness of 245 m in Baker Canyon 1.5 to 3 km south of Oak Flat. In a cliff on the north side of the divide between Baker and Black Star Canyons, the lower part of the member is 202 m thick. From Baker Canyon south to Williams Canyon the member averages about 120 m thick, but it is thicker in Hall Canyon between Ladd and Baker Canyons, where it measures 365 m. Texas Co. well, Irvine (NCT-1) No.1, just north of Ir- vine Park, drilled through the Baker Canyon Conglom- erate Member from 1,029 m depth to the bottom of the hole at 1,074 m. Much farther south (along section R-S, pl. 3), West American Oil Co. well, Irvine No. 1, near Irvine Ranch headquarters, and Texas Co. well, Ir- vine (NCT-2) No.1, in Little Joaquin Valley, drilled to basement without penetrating the member. Still farther south, however, beyond the south margin of the map, the conglomerate reappears, in Shell Oil Co. well, Irvine Corehole No. 5, between 929 m depth and the bottom of the hole, and continues southward in Shell Oil Co. well, Irvine Corehole No. 7, and in Morton and Sons wells, El Toro No.14-1 and Irvine No. 174-1 (Schoellhamer and Vedder, 1975). The absence of this unit from the subsurface section beneath the south- central part of the map area may indicate its gradation there into the Holz Shale Member in the northwest- trending central strip of the incipient Los Angeles basin which later ceased to subside and became part of the Anaheim nose (see section on "Subsurface Struc- tures South of El Modeno Fault"). PETROGRAPHY Thin sections from sandstone beds in the Baker Can- yon Conglomerate Member show variations in the proportions of the prevailing constituents: quartz, plagioclase, biotite, volcanic rock, and rather rare or- thoclase. The most siliceous sample is composed of grains 0.6 mm across (table 3). The least siliceous sample, from the nonmarine lower part of the unit on the Riverside Freeway, is composed of grains up to 1.7 mm in diameter (table 3). Other samples from the nonmarine beds are similar. A single thin section form the marine upper part of the unit represents the sandstone along the Riverside Freeway. This marine GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA TABLE 3.-Petrography of the Ladd Formation Volume Rock type Composition percent Comments Baker Canyon Conglomerate Member Nonmarine Quartz.......................; 38 sand- i 30 stone, lower part of member. Orthoclase ...... Rock fragments.... Of Bedford Canyon Formation or similar metasedimentary unit. MulhiK 4.2; le ole. 9 _ Composed of clay, mica shreds, and rock powder. Nonmarine Quartz ......................... 8 sand- FlagloclH#e 7 stone. >: $ lower __ Rock fragments ...24 _ Of Bedford Canyon S?) Formation part of _ Rock fragments ...20 _ Of Santiago Peak (?) Volcanics member. Rock fragments _...4 _ Of plutonic rock. Epidote ............ 204 Opaque minerals.... werd 00. _..29 _ Composed of clay, rock powder, and minute mineral grains. Marine Quarts e 2.0. .. oie 22 sand- Plagioclase (includes 25 stone, microcline). UPDEF -> cie 1 part of _ Muscovite ._..... ... Trace Of Bedford Canyon (?) Formation. ...2 - Plutonic rock. Schist. member. Rock fragments............... 5 Rock fragments.. Rock fragments Calcite cement .............. 44 Holz Shale Member Sandstone; Quartz 39 near basePlagioclase .... of Orthoclase * member. Biotite .... Chlorite ... Of sedimentary and plutonic rock. Rock fragments 2 --.6 _ Chloritic. Matrix .... Sandstone, Quartz .... middle - Andesine........ part Biotite and chlorite... of Rock fragments.... ...2 _ Of sedimentary rock. member. Opaque minerals .. Matrik........... ..43 _ Composed largely of calcite. Sandstone. Quartz ........................ 37 upper _ Plagioclase .. ..81 part of - Biotite .._. fd member. Chlorite .. Muscovite Opaque minerals.............. 1 Matrix :;.........-. ...24 _ Calcified and silicified clay. Concretion Quartz ...... from Plagioclase sandy _ Biotite... shale, _ Muscovite near Chlorite.......... top of _ Rock fragments Of sedimentary rock. member. Opaque mineral: MaHiX os Chiefly calcite. sandstone sample is made up of grains up to 3 mm in diameter (table 3). Pebbles, cobbles, and boulders from one locality in the lower part of the Baker Canyon Conglomerate Member were studied petrographically. The sample was taken about 100 m stratigraphically above the base of the member in Santa Ana River gorge, at the south edge of the Riverside Freeway. Here the largest boul- ders, rounded and up to 2 m in diameter, are all pale biotite granite, but by far the commonest clasts are dark-green tuff, breccia and porphyry of "Baker Can- yon type" (Woodford and others, 1968, p. 1471). The porphyry is similar to that which intrudes the Santiago Peak Volcanics near Sierra Peak. A sample of 100 clasts up to 30 cm in diameter, was examined by a combination of thin sections (20 representative sam- ples), immersion oil study of mineral grains, and hand GEOLOGY OF THE SANTA ANA MOUNTAINS lens. They are identified below; note the absence of quartzite pebbles and cobbles: 63 Dacite tuff and 37 with large quartz grains; 26 breccia. with small or no quartz grains. 13 Quartz- biotite Mostly granite, one with tour- plutonite. maline. 6 Dacite porphyry...__..... Without quartz phenocrysts or with quartz crystals much smaller than those at Sierra Peak. 4 Andesite tuff and breccia. 4 Quartz-rich gneiss with biotite and feldspar. 2 Quartz latite porphyry... Similar to Temescal Wash por- phyry in Basement complex 17 km east. 2 Pale quartz monzonite or quartz diorite porphyry. 2 Granite aplite. 1 Albite porphyry ___.... Similar to Peters Canyon type, common some places in basal conglomerate of un- differentiated Sespe and Vaqueros Formations. 1 Biotite granophyre. 1 Biotite granite gneiss. 1 Granitic metabreccia. AGE AND CORRELATION The late Turonian age of the Baker Canyon faunas is best defined by the presence of Subprionocyclus, an ammonite genus of cosmopolitan range. Other fossils are included in the megafossil lists in this report and in Packard (1916) and Popenoe (1937, 1941). Popenoe (1942, p. 178) assigned the molluscan fauna of the Baker Canyon Conglomerate Member to the Glycymeris pacificus fauna of Turonian age. Two rather indistinct faunal facies occur in the Glycymeris pacificus fauna. The lower, the Trigonarca californica facies, is characterized by a flood of thick-shelled bivalved mollusks. T. californica Packard and Ac- teonella oviformis Gabb are the most abundant species. The higher, the Cucullaea gravida facies, has a greater proportion of thin-shelled pelecypods and gastropods and is found mostly in finer grained sandstone. HOLZ SHALE MEMBER The areal distribution of the Holz Shale Member of the Ladd Formation is essentially the same as that of the underlying Baker Canyon Conglomerate Member. I? type locality is at Holz Ranch on the north side of Silverado Canyon just west of the mouth of Ladd Can- yon (Popenoe, 1942, p. 171). Its main outcrop belt ex- tends northward along the eastern edge of the map D15 area from Modjeska to the mouth of Coal Canyon just south of the Santa Ana River, and thence eastward as far as Fresno Canyon. The Holz Shale and Baker Can- yon Conglomerate Members have not been separated on the geologic map southeast of Fresno Canyon and are shown as the Ladd Formation, undifferentiated. Other outcrops are in faulted anticlines north and northeast of Irvine Lake. Subsurface data indicate that the Holz is present southeast of Tustin, and Shoell- hamer and Vedder (1975) have recognized the member in wells drilled in the San Joaquin Hills to the south. The Holz Shale Member characteristically erodes to form smooth rounded slopes that are covered with sparse brush and thick grass where sufficient soil has developed. The contact between the Baker Canyon Conglomerate and Holz Shale Members everywhere seems to be gra- dational in a succession of sandstone and gray shale beds. In mapping, the contact was drawn arbitrarily at the top of the highest conspicuous sandstone bed. and this lithologic distinction is undoubtedly time- transgressive. STRATIGRAPHY AND LITHOLOGY The Holz Shale Member is made up chiefly of thin to thick beds of siltstone, sandy siltstone, and shale. It contains concretions ranging from 5 cm to 1 m in thickness that are flattened parallel to the bedding and that vary from nearly pure calcite to limy shale. Cal- careous and arenaceous foraminifers are present throughout, and megafossils are locally abundant. A section of the Holz Shale Member measured on the south side of Silverado Canyon is 350 m thick, and the member may be 460 m thick a little farther north. In Black Star Canyon a measured section is at least 230 m thick. In the complexly faulted area north of the Whit- tier fault, the member is at least 300 m thick. West of the outcrop area, the Holz was found to be 460 m thick in Texas Co. well, Irvine (NCT-1) No. 1, northeast of Irvine Park, 730 m thick in Texas Co. well, Irvine (NCT-2) No. 1, in Little Joaquin Valley due east of Santa Ana and Tustin, and 565 m thick in Shell Oil Co. well Irvine Core Hole No. 5, at the south edge of the map area. Between Williams and Black Star Canyons the member includes cliff-forming lenses that are chiefly sandstone and conglomerate, as much as 60 m thick, and unfossiliferous. They are composed of alternating sequences of conglomerate, sandstone, siltstone, and pebbly mudstone (fig. 9). The conglomerate clasts, up to 1 m in diameter, are largely quartz latite or dacite porphyry similar to those in the Baker Canyon Con- glomerate Member. The sandstone and siltstone con- D16 tain numerous black carbonaceous chips and particles. Many beds within the lenses are graded, and some sandstone beds are cross laminated, suggesting deposi- tion by turbid flows. They are the only such flow de- posits found in the Cretaceous sequence in the north- ern Santa Ana Mountains. PETROGRAPHY Four thin sections give indications of the nature of the coarser grains in the Holz Shale Member (table 3). Three are from sandstone beds in shale. One sandstone specimen is from a nearly basal bed in Shell Oil Co. well, Irvine Core Hole No. 5, close to the south edge of the map area. A section from a second bed is somewhat higher in the Holz at the east edge of Irvine Block 113 near Fremont Canyon (table 3). A section from a third bed is in the upper part of the Holz Shale Member southeast of Fremont Canyon (table 3). A section from GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA a concretion in sandy shale is near the top of the Holz southeast of Fremont Canyon. Collectively these sam- ples show that quartz commonly exceeds 35 percent, and feldspar (almost entirely plagioclase) 25 percent. Rock fragments are variable but may constitute as much as 20 percent of the rock. AGE AND CORRELATION Molluscan faunas indicate a Late Cretaceous age for the Holz Shale Member. The basal 100 m of the Holz yields a sparse molluscan fauna assigned to the Turo- nian Stage. This fauna is similar to the uppermost fauna in the Baker Canyon Conglomerate Member. The remainder of the Holz was assigned by Popenoe (1942) to his Turritella chicoensis and Turritella chicoensis perrini divisions, the lower and middle faunal divisions, respectively, of the Glycymeris veatchii fauna (Campan- ian Stage). FIGURE 9.- Sedimentary features of graded lens in the Holz Shale Member of the Ladd Formation, showing unsorted conglomerate, graded bedding in sandstone, and truncated cross lamination, in a section 150 m upstream from where Black Star Canyon Road leaves stream bottom. GEOLOGY OF THE SANTA ANA MOUNTAINS Crassatella cf. C. tuscana, Etea angulata, Parallelo- don cf. P. vancouverensis, Eriphyla lepidus, and Tur- ritella chicoensis chicoensis are restricted to the T. chicoensis division. Assemblages of the Turritella chicoensis perrini divi- sion occur in calcareous and sandy beds near the top of the Holz Shale Member and are most abundant a little north of Williams Canyon. The fossils in these beds are remarkable for their large size, robust shells, and numbers of species that are rare or absent elsewhere. Only a few species are restricted to this division, the most abundant being T. chicoensis and Crassatella cf. C. lomana (long form). Merle Israelsky in consultation with Boris Laiming (written commun., 1952) assigned foraminiferal as- semblages in samples from outcrops of Holz Shale Member on the north side of the mountains to Goud:- koffs (1945) G-1 zone. These samples came from the northwestern and northeastern parts of sec. 36, T. 3 S., R. 8 W., near Santa Ana Canyon and the center of sec. 7, T. 4 S., R. 7 W., about 2 km northwest of Oak Flat. A. A. Almgren (in Colburn and Fritsche, 1973, p. 40 and fig. 3) notes that the middle part of the member in Silverado Canyon contains foraminifers that suggest Goudkoff's G-1 zone, which Almgren tentatively corre- lates with the upper part of the Coniacian, Santonian, and lowermost Campanian Stages. Popenoe and others (1960) correlate the G-1 zone with the Coniacian and lower part of the Santonian Stages. H. R. Lang (1978) assigns a range of Turonian to Campanian to the Sil- verado Canyon Section. WILLIAMS FORMATION The Williams Formation was named and described by Popenoe (1937, p. 380; 1942, p. 173) for exposures along Williams Canyon near its mouth. He divided the formation into the Schulz Member and Pleasants Sandstone Member. The Schulz Member was renamed the Schulz Ranch Sandstone Member by Woodring and Popenoe (1945). SCHULZ RANCH SANDSTONE MEMBER The type locality of the Schulz Ranch Sandstone Member is approximately 0.4 km upstream from the mouth of Williams Canyon near the west boundary of Schulz Ranch (Popenoe, 1942, p. 173-174). From the southeast corner of the map area near Modjeska to Black Star Canyon, the Schulz Ranch Sandstone Member crops out in a narrow belt. Between Black Star and Fremont Canyons, exposures of the member are more extensive due to faulting and consequent repeti- tion of section. North of Fremont Canyon the outcrop narrows and trends northward along Coal Canyon until it disappears beneath the alluvium of the Santa Ana D17 River. The member is also present at the surface in iso- lated fault blocks north and south of Santiago Creek between Irvine Park and Irvine Lake. The Schulz Ranch Sandstone Member is a prominent cliff-forming unit throughout the area, and its bold outcrops of yellowish-white to light-brown sandstone contrast sharply with the darker gray, smooth, gentle slopes of the underlying Holz Shale Member of the Ladd Formation (fig. 10). STRATIGRAPHY AND LITHOLOGY The Schulz Ranch Sandstone Member of the Williams Formation unconformably overlies the Holz Shale Member of the Ladd Formation and nowhere in the map area overlaps older rock units. Its basal thick- bedded pebbly sandstone and conglomerate contrast sharply with the underlying shale, although at places angular clasts of gray siltstone of the Holz and blocks of conglomerate, some as much as 10 m on a side con- taining fossils characteristic of the Baker Canyon Member of the Ladd Formation, are distributed errati- cally in this part of the Schulz Ranch Sandstone. These clasts and blocks suggest a local unconformity at the base. Presumably these transported bocks were emplaced by submarine landslides. The Schulz Ranch Sandstone Member is typically coarse-grained cream-white to yellowish-brown very poorly sorted feldspathic sandstone, composed mainly of angular to subrounded grains of quartz and feldspar and various amounts of black to black crinkly biotite flakes in a sparse clayey matrix. It also contains numerous isolated pebbles and cobbles, and some well-rounded pebbles, cobbles, and boulders, as much as 30 cm in diameter and averaging 5 to 10 cm, are concentrated in beds a meter or so thick. Most beds in this member are massive, but some are crossbedded. Between Black Star and Fremont Canyons, con- glomeratic sandstone is interbedded with siltstone beds 3 to 9 m thick. The sandstone here contains cannonball concretions several centimeters to 1 meter in diameter, cemented by calcite. Concretions, elongate parallel to the bedding, are also present. PETROGRAPHY Six samples from the Schulz Ranch Sandstone Member were point-counted in thin section (table 4). Three are relatively fine-grained and well-cemented sandstone rich in plagioclase. One of these samples is from near the base of the member southeast of Fre- mont Canyon. The second is medium grained and from the lower part of the member, south of Modjeska in the southeastern part of the map area. The third is fine to medium grained and from the middle part of the member, north of Fremont Canyon. The two northern D18 samples are unusually rich in biotite, and the southern one lacks mica. The other three samples are typical of the Schulz Ranch Sandstone Member. They are very coarse grained sandstone and are poorly cemented and poorly sorted, with rare small pebbles, and have exceptionally abundant alkali feldspar. One of these samples is from the ridge northwest of Black Star Canyon, one from the east edge of Irvine Park, and one from elevation 535 m (1,750 ft), 3 km east of Santiago Dam. SUBSURFACE DISTRIBUTION The Schulz Ranch Sandstone Member thickens to- ward the northwest. Sections T-X and U-W (pl. 3), south of Silverado Canyon and east of Santiago Creek, show thicknesses near 85 m. A measured section along the fire road east of Baker Canyon, in the NE!/« sec. 7, T. 5 S., R. 7 W., totals 75 m im thickness. Section H-O (pl. 3) indicates a thickness of about 200 m between ® 3% GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA Fremont and Black Star Canyons. Elsewhere in this area, and as drilled farther west in Texas Co. well, Ir- vine (NCT-1) No. 1, just north of Irvine Park, the maximum thickness of about 280 m occurs. AGE AND CORRELATION The Schulz Ranch Sandstone Member is sparsely fos- siliferous throughout the area. Four or six fossil localities are in carbonate-cemented sandstone of con- glomerate near the base of the member, all west and north of Baker Canyon. Locality F-37 on the west wall of Black Star Canyon near Hidden Ranch is in blocks of Baker Canyon Conglomerate redeposited in the basal Schulz Ranch Sandstone. The others are in siltstone northwest of Fremont Canyon and near the top of the member northeast of Irvine Lake. W. P. Popenoe (oral commun., 1977) would place some of these beds in the Holz Shale Member of the Ladd Formation. Localities FigcurE 10.- Contact (at center) between the Holz Shale Member of the Ladd Formation and the overlying Schulz Ranch Sandstone Member of the Williams Formation taken from road connecting Main Divide Motorway with road in Fremont Canyon, Irvine Block 34. Basal part of the Schulz Ranch Sandstone Member shown here is about 50 m (150 ft) thick. View northeast. GEOLOGY OF THE SANTA ANA MOUNTAINS TABLE 4.-Petrography of the Williams Formation Volume Rock type pergent Composition Comments Schulz Ranch Sandstone Member Sandstone Quartz ......... (near _ Andesine ...... base of - Orthoclase and microcline ...1 mem- BIOULE . 16 ber). Rock fragments . oA Opaque minerals ace Matrix ..........c... Sandstone QURELE L 38 lower - Plagioclase ... "14 part of _ Rock fragments. mem- Opaque minerals ber). Epidote .. Matrix ... Sanstone (middle part of member north of Fremont Canyon). Sandstone Quartz ...._........ (ridge _ Alkali feldspar north- _ Oligoclase .. west Biotite...... of Black Rock fragments. Star 8 Canyon). Sandstone Quartz........................ 50 (east __ Alkali feldspar.. ..20 edge of - Oligoclase .... Irvine _ Biotite ...._..- 2: Park). _ Rock fragments.._______.__.... 5 Mati LoZ. cie otes cen ool 8 Sandstone Quartz ...... am Biotite ...... . Rock fragments............... 4 MAW IS 9 Includes a little chlorite. Composed of 5 percent quartz and 9 percent calcitized clay and mica. Composed of silicified clay Composed of silicified clay. Largely microcline and perthite. Of Bedford Canyon Formation. Composed of clay. Largely perthitic orthoclase. Sandy siltstone of Bedford Canyon (?) Formation. Clay. In part perthitic. With some andesine. 2 percent fine-grained quartzite, 1 percent Bedford Canyon (?) Formation sandstone, and 1 percent quartz-orthoclase rock. Fine sand. Pleasants Sandstone Member Sandstone Quartz... near _ Andesine base of - Biotite and chlorite .. mem- Muscovite .......... ber). Rock fragments. Matrix ..... Sandstone Quartz (low in - Andesi mem- Microline .. ber). Biotite ..... Muscovite . Epidote........ Rock fragments. Matrix _-_ scour delles 52 Sandstone Quartz ........................ 21 (from. Flagloclase................... 10 middle third of - Biotite and chlorite........... 4 mem- Muscovite ...... Trace ber). Epidote ...... Trace Opaque minerals .. ash Matrix.:........ ..64 Sandstone Quartz... (near _ Andesine... top of _ Orthoclase..... mem- __ Biotite and chlorite .. ber). Muscovite .... Opaque mine seee Matrix........... ..53 Micaceous clay with epidote and calcite. 25 percent clay; 27 percent calcite replacing silica. Both plagioclase and quartz embayed by matrix. Embayed by matrix. Calcitized micaceous clay. near the head of Black Star Canyon yield pelecypods of the genera Trajanella, Opis, and Coralliochama. Coral- liochama, a rudistid, indicates a shallow marine envi- ronment. Elsewhere, the presence of Turritella chicoen- sis indicates the Glycymeris veatchii fauna of the Cam- panian Stage. PLEASANTS SANDSTONE MEMBER The type locality of the Pleasants Sandstone Member D19 is at Pleasants Ranch at the mouth of Williams Canyon (Popenoe, 1942, p. 175). The distribution of the member is irregular because of faulting and the pro- found unconformity at the base of the overlying Sil- verado Formation of Paleocene age. The Pleasants Sandstone Member extends from the southeast corner of the map area northward almost to Silverado Canyon, north of which it has been overlapped by younger strata for about 1,200 m along the strike. It reappears on the ridge southeast of Baker Canyon and is well ex- posed in fault blocks as far northwest as the Fremont Canyon drainage. Isolated fault blocks of Pleasants Sandstone Member are present north and south of Ir- vine Park and between Blind and Fremont Canyons. The northeastermost exposure of the member is in Ir- vine Block 35, on the ridge between Fremont Canyon and the Gypsum Canyon drainage. Farther north and east, it is overlapped by the Silverado Formation. The contact between the Pleasants Sandstone Member and the underlying Schulz Ranch Sandstone Member appears to be gradational (fig. 11). The boun- dary is rarely well exposed, for the Pleasants is easily weathered and creeps down over the cliffy Schulz Ranch Sandstone Member beneath. The contact is marked by a change in slope as well as a change from the creamy-white pebbly sandstone of the Schulz Ranch to the brown and gray fine-grained sandstone of the Pleasants and usually can be located within a meter or so. STRATIGRAPHY AND LITHOLOGY The Pleasants Sandstone Member is 0 to 395 m thick; the maximum thickness occurs north of Irvine Park, in- cluding that penetrated in the Texas Co. well, Irvine (NCT-1) No. 1. A complete section of the Pleasants Sandstone Member, about 150 m thick, is well exposed along the Santiago Truck Trail at the extreme south- east corner of the map area. Here the uppermost part of the Schulz Ranch Sandstone Member is typical poorly bedded cream-white feldspathic sandstone, in contrast to the 1 meter of pinkish-brown, somewhat better bedded, poorly sorted feldspathic sandstone and sandy siltstone containing black carbonaceous frag- ments, at the base of the Pleasants. The next higher 1 meter of section consists of rather well bedded mica- ceous sandstone grading upward into typical structure- less soft gray and brown sandstone. A few 0.3-m-thick beds of gritty sandstone contain pebbles as much as 5 cm in diameter. A prominent 6-m-thick bed 15 m above the base is composed of coarser feldspathic sandstone with crinkly biotite flakes and some musco- vite. The next higher 120 m or more of the Pleasants is made up of two interbedded types of sandstone; the more abundant one is massive and characterized by biotite and black carbonaceous fragments, the less abundant one is harder, thin bedded, less silty and D20 characterized by biotite and some muscovite. Both types of sandstone contain richly fossiliferous ellipsoi- dal concretions. At many places, a few thin pebble layers grade sequentially upward into pebbly sandstone and medium-grained sandstone. In all areas the Pleas- ants includes thin discontinuous conglomerate lenses. Northeast of Irvine Lake the upper beds include a zone of calcareous sandstone and, north of Irvine Park, a 9-m-thick coarse massive concretionary sandstone lens that displays cavernous weathering. In general, the upper part of the member is coarser grained than the lower part. PETROGRAPHY Thin sections from the Pleasants Sandstone Member show that it contains less feldspar than older Upper Cretaceous sandstones and that it more commonly con- GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA tains muscovite (table 4). One thin section from near the base of the member on the Santiago Truck Trail, south of Santiago Creek in the southeast corner of the map area, has grains up to 1.3 mm diameter, averaging 0.07 mm. Another thin section from low in the member near Santiago Creek 3 km farther north has grains up to 0.55 mm, averaging 0.06 mm; one from sandstone in the middle third of the sequence on the Santiago Truck Trail has grains up to 0.47, averaging 0.05 mm, and one from a fossiliferous sandstone near the top of the member just southeast of Black Star Canyon has grains up to 0.29 mm, averaging 0.04 mm. AGE AND CORRELATION Mollusk assemblages in the Pleasants Sandstone FIGURE 11.- Contact (directly below hammer handle) between the Schulz Ranch Sandstone (on right) and Pleasants Sandstone Members (on left) of the Williams Formation; contact is gradational through about 1 meter. Just east of Hill 1925 on Santiago Truck Trail. View north. GEOLOGY OF THE SANTA ANA MOUNTAINS Member are assigned by Popenoe (1942) to the highest faunal division of the Glycymeris veatchii fauna, the Metaplacenticeras pacificum division, the youngest faunal division of the Cretaceous in the Santa Ana Mountains. Species of mollusks are numerous, but few of those that occur abundantly are restricted to the di- vision. Lembulus cf. L. striatula, Atira ornatissimus, Legumen ooides, and an undescribed species of Meekia generally occur no lower in the Santa Ana Mountains, and Calva bowersiana is almost entirely restricted to this division. The ammonite Metaplacenticeras pacifiecum is a common and characteristic fossil that oc- curs at almost every fossil locality in the member. Mat- sumoto (1959-60, v. 2, p. 66), basing his conclusions upon the known stratigraphic range of the genus, re- fers the beds containing it to the upper part of the Campanian Stage. Fossils from localities in the Pleasants Sandstone Member are cited in this report in the "List of Megafos- sils" section. TERTIARY SYSTEM PALEOCENE SERIES SILVERADO FORMATION Sedimentary rocks of Paleocene age were first recog- nized and described in the northwestern Santa Ana Mountains by Dickerson (1914), who assigned them, primarily because of faunal similarity, to the Martinez Formation of central California. English (1926) fol- lowed the usage established by Dickerson. Woodring and Popenoe (1945) measured stratigraphic sections and identified fossils from the Paleocene strata in sev- eral parts of the northwestern Santa Ana Mountains. They named the Silverado Formation and defined its type region as the area about 1 km northeast of Irvine Park. Their measured composite section northeast of Irvine Park, block 19, between two tributaries to San- tiago Creek showed about 350 m of strata exposed above the Pleasants Sandstone Member of the Williams Formation and below the Santiago Formation. The lower part of the Silverado Formation contains two relatively thin, distinctive, and widespread clay beds that serve as useful stratigraphic markers throughout most of the map area (pl. 1). The lower marker, defined by Woodring and Popenoe (1945), is called the Claymont Clay Bed, a name derived from a clay mine on the west side of Coal Canyon in Irvine Ranch Block 33, 2 km south of the Santa Ana River. The type locality for the Claymont Clay Bed is near the divide between Gypsum and Fremont Canyons (Gyp- sum Creek and Sierra Canyon on Woodring and Popenoe's map) and includes the excellent exposures in the southern part of Irvine Ranch Block 34. The upper marker is the Serrano Clay Bed, named for the Serrano Clay pits about 1 km southeast of the divide between Santiago and Aliso Creeks in the southeast corner of D21 the map (see. 32, T. 5 S., R. 7 W.; Sutherland, 1935, p. 81; Woodring and Popenoe, 1945). Outcrops of the Silverado Formation are present in fault blocks extending from the northeast corner of the map area to Irvine Park; from there a nearly continu- ous belt of outcrops extends along the northeast side of Santiago Creek to the southeast corner of the map area. The formation also is exposed over small areas on the southwest slope of the foothills in the vicinity of Rattlesnake and Bee Canyons. Data on the subsurface distribution of the Silverado Formation are incomplete. Wells drilled near outcrops yield few additional data, and wells in the northwest part of the map have not been drilled deep enough to penetrate the Silverado. . The presence of the Silverado Formation in the Texas Co. well, A 13-1, located about 3 km west of Anaheim (Woodring and Popenoe, 1945; Schoellhamer and Woodford, 1951, suggests that the formation may ex- | tend over much of the eastern Los Angeles basin (Yerkes and others, 1965, fig.7). Southeast of Tustin, however, several wells, including the Amerada Pe- troleum Corp. well, Irvine No. 63-1, and the Shell Oil Co, wells, Irvine Coreholes Nos. 4, 5, 2, and 12, reached rocks of Late Cretaceous age without passing through the Silverado Formation. It may have been re- moved locally by erosion in middle Tertiary time, as the Silverado crops out in the San Joaquin Hills to the south (Vedder and others, 1957; Yerkes and others, 1965, fig.7). The contact between the Silverado Formation and the underlying rocks is everywhere and unconformity rep- resenting an episode of deformation and extensive ero- sion and deep weathering between the deposition of marine Upper Cretaceous rocks and Paleocene rocks. An angular discordance has not been observed, but the Silverado rests on progressively older rocks from southwest to northeast. Near Irvine Park the formation rests on the Pleasants Sandstone Member of the Wil- liams Formation. Northeastward in the Fremont Can- yon drainage, the Silverado Formation transgresses the eroded edges of the Schulz Ranch Sandstone Member of the Williams Formation and the Holz Shale Member of the Ladd Formation. There, at least 370 m of Upper Cretaceous strata was removed before deposition of the Paleocene. A few kilometers east of the map area, east of the Elsinore fault, the Silverado rests directly on the Bedford Canyon Formation and granitic rocks of the Southern California batholith. Where the uppermost part of the Silverado Forma- tion contains marine fossils, it consists of fine- to medium-grained sandstone, and the contact with the overlying basal conglomerate of the Santiago Forma- tion is sharp. Where both formations are nonfossilifer- ous, the contact is commonly difficult to discern, as it lies between similar rocks, without apparent discor- dance. North of Irvine Lake and west of the site of the D22 Santiago Coal Mine, however, its uppermost bed con- tains a brackish-water fauna (Woodring and Popenoe, 1945). The mineral and rock fragments that make up the clastic sedimentary rocks of the Silverado Formation are traceable to crystalline and semicrystalline bedrock sources to the east. Davis (1978) determined current directions at 85 places in the Silverado Formation, probably all in nonmarine parts. All of his conclusions were based on dip-corrected measurements or crossbedding. At 52 data points in three localities near Irvine Lake the cor- rected dips were northwest of north, away from the re- gion of exclusively continental deposition. One of these localities was below the Claymont Clay Bed, 3 km north of the lake; the other two were just above the clay, one north of Irvine Park, the other just north of the mouth of Black Star Canyon. North of the mouth of Silverado Canyon, 8 km to the south, the crossbeds originally dipped west or southwest. Farther south, near Mod- jeska, corrected crossbed dips were variable, but all eastward. STRATIGRAPHY AND LITHOLOGY The Silverado Formation is characteristically com- posed of four units , in ascending order: unit A, basal conglomerate; unit B, a rather thin sequence of sandstone and siltstone: unit C, the Claymont Clay Bed; and unit D, an uppermost, thick sequence of sandstone, siltstone, and conglomerate, which includes the Serrano Clay Bed. Units A, B, and C are non- marine; unit D is in part marine in the type region of the Silverado and farther northeast. The formation probably is wholly nonmarine in the southeastern part of the map area, beyond Black Star Canyon. There the Serrano Clay Bed occurs 75 m above the Claymont Clay Bed. In its type region northeast of Irvine Park, the Silverado Formation is about 370 m thick. It reaches its maximum thickness of about 450 m just to the east, '/2 km west of the old Santiago Coal Mine (Woodring and Popenoe, 1945); thence its thickness decreases eastward to about 240 m southeast of Baker Canyon. In the north, on the ridge between Coal and Gypsum Canyons, the formation is about 200 m thick; about 370 m was penetrated just beyond the northeast- ern corner of the map area, in Godfrey Drilling Co., Botiller prospect well No. 1. UNIT A, BASAL CONGLOMERATE Unit A is up to 35 m thick, most commonly between 2 and 12 m. At the north in the Coal, Gypsum, and Fre- mont Canyons area (pl. 4), it is 2 to 6 m thick. Just north of lower Santiago Creek, from Irvine Park east to GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA the old Santiago Coal Mine, it is as much as 8 m thick, but locally it is merely a thin layer of coarse gritty sandstone. Farther southeast the thickness varies errat- ically and on the divide between Santiago and Aliso Creeks reaches the maximum of 40 m. The basal conglomerate is unbedded, unfossiliferous, grayish to yellowish brown or red, and almost certainly nonmarine. It is composed of pebbles, cobbles, and rare boulders as much as 45 cm in diameter, mostly subrounded, in a clayey arkosic sandstone matrix. About one-third of the pebbles and larger clasts are dark-gray, mildly metamorphosed sedimentary rocks, largely metasandstone and metasiltstone probably de- rived from the Bedford Canyon Formation. About one- fourth are quartzite. Perhaps 3 percent are granite gneiss. The other clasts are mostly thoroughly weath- ered biotite-rich quartz plutonite, pale siliceous vol- canic rocks, vein quartz, feldspathic sandstone, siltstone, and limy sandstone similar to the concretions of the Pleasants Sandstone Member of Late Cretaceous age. UNIT B, SANDSTONE AND SILTSTONE Unit B overlies the basal conglomerate and is as much as 55 m thick. It is best exposed in Irvine Block 34, on the divide between Fremont and Gypsum Canyons (pl. 4) and is made up of interbedded layers of sandstone and siltstone. Most of the sandstone beds are composed of quartz and clay (up to 60 percent), more or less al- tered feldspar, and partly altered biotite. The upper- most bed, just below the Claymont Clay Bed, is in most places a golden-yellow or dirty-white sandstone made up of quartz without feldspar and a clay mineral. At places the clay mineral occurs as large flakes, an alter- ation product of biotite. Rare jet-black pebbles are schorl with 60 to 80 percent quartz and probably were derived from the identical distinctive tourmalinite so abundant in the quartz plutonite bedrock outside the map area at the abandoned Cajalco tin mine west of Lake Mathews, 8 km northeast of the Santa Ana Moun- tains. In a few places the bed just below the Claymont Clay Bed is either a micaceous siltstone or a fine- grained quartz-pebble conglomerate. Some of the lower sandstone layers are crossbedded. Farther south, in the north corner of Irvine Block 71, 2.6 km northeast of the Santiago Creek dam, 1 m of dark carbonaceous to lig- nitic shale is present in a gritty sandstone sequence near the top of the unit. In the southeastern part of the map, a well-exposed section across unit B is 32 m thick. Thin sections of sandstone from the main part of unit B and from the uppermost bed, 2 m below the Clay- mont Clay Bed, on the divide between Coal and Frem- ont Canyons, were examined (table 5). GEOLOGY OF THE SANTA ANA MOUNTAINS UNIT C, THE CLAYMONT CLAY BED The Claymont Clay Bed seems to lie conformably on sandstone of unit B (pl. 4). It is only a meter or so thick in the Santa Ana Mountains, but it weathers to a TABLE 5. -Petrography of the Silverado Formation: units B and C Rock type Composition Volume Comments percent Sandstone, Quartz........................ 22 unit B - Plagioclase . zee A0 (basal _ Orthoclase..... Trace art, Rock fragments............... 6 antiago Matrix .......... 56 Creek, _ Biotite-chlorite................ 5 Sedimentary, plutonic, and volcanic rocks. Calcite replaces original matrix. Crushed and spread biotite is bleached; fresh near biotite in undeformed books. Mod- Opaque minerals ........ Trace jeska). - Sphene, epidote, garnet, 1 and zoisite. Sandstones Quarts ..1...........0....2. 41 Boundaries of quartz grains often sutured and unit B obscured by silicification. (core _ Plagioclase .... f sample - ts from Rock fragments . .20 _ Sedimentary (Bedford Canyon ? Formation) Clay- and plutonic rocks. mont Matrix............ .23 _ Clay, silica, chlorite, and microcrystalline Clay rock powder. mine, Biotite-chlorite... ted Coal Opaque minerals ........ Trace Canyon). Tourmaline and Trace muscovite. Sandstone, Quartz 47 Whit B) Biotite 53 _ Altered. (upper- most bed, divide between Coal and Fremont Canyons). Clay, Kaolinite ._. 80 _ 7 percent pisolites, 73 percent matrix. unit C_ Quartz .... ...19 _ In matrix and pisolites. (lower _ Tourmaline..... Trace 0.6 m; _ Opaque minerals.............- north of Baker Canyon). Clay, RHBHHILE .C.... 72 - Matrix. 4 MUC) Quartz... 00.20.0000 28 - Grains up to 1.34 mm diameter; a few partially (opposite replaced by kaolinite. Mod- % jeska). Clay, Kaolinite 1-1 96 _ Matrix. _ QuarH 2. lle... eel 2 - Grains up to 0.6 mm diameter; partially (from replaced Santiago by kaolinite. TTTUCK ..... 262. C222 02 ce 1 Trail). _ Opaque minerals. A Clay, Kaolinite ....... 99 _ Pisolites, maximum diameter 3.4 mm. unit C _ Quartz... Grains, maximum diameter 0.6 mm. ( near Tourmaline ... Trace section A Zircon..................... Trace plate 4). Clay, Kaolinite ..----.....0-2. dels 99 _ 16 percent birefringent pisolites, 7 percent unit birefringent and after quartz, 76 percent (lower matrix. 0.6 m, _ Quartz .... divide _ Biotite .... .. Trace between Opaque minerals ........ Trace Gypsum and Fremont Canyons). Clfiit C $3223? Corroded and partly replaced by kaolinite; (divide - Opaque minerals.............- 1 Limonite? between Gypsum and Fremont Canyons, 1.8 m above base). Clay, unit (top. ridge Kaolinite E. .... .cc: 42 between Biotite ......... a Gypsum Rock fragments ............--- 1 and Fremont UAT .de ee 54 Corroded and partly replaced by kaolinite; unusually coarse and up to 2 mm in diameter. More or less altered. D23 unique fiery red. Outside these mountains it is present for several kilometers to the east, near Elsinore, and for many kilometers to the south, where clay miners call it "tierra colorado." Variegated beds in Silverado Formation in the San Joaquin Hills to the southwest possibly are equivalent to this part of the section (Ved- der, 1975). The Claymont Clay Bed is 20 to 55 m above the base of the Silverado Formation (pl. 4); it is commonly about 1 m thick but reaches a maximum of 3 m. Its composition and economic importance have been de- scribed by Sutherland (1935) and Burchfiel and Mul- ryan (1940). The Claymont is not present either in the western part of Irvine Block 34 (southeast of Gypsum Canyon) or at the north edge of the mountains, just south of the Santa Ana River. The Claymont Clay Bed is yellow brown or greenish gray and weathers red (fig. 12). It is massive and un- stratified. It contains angular quartz grains as much as 2 mm across; in most places it contains balls or irregu- lar clasts of distinctive clay up to 12 mm across, some nearly spherical, some with pisolitic shells, and some containing altered fragments of the Bedford Canyon Formation. The pisolites (figs. 13A, B) are commonly deep brown and darker than the matrix; some pisolites near the base of the unit are white. Flakes of golden-yellow kaolinite after biotite and angular quartz grains are commonly present in the lower part of the clay bed. Vertical variations in the size of the quartz grains are not noticeable in the out- crop; in areas where the clay is very pisolitic, the piso- lites tend to be more abundant in the middle of the bed. However, lateral variations in the amount of quartz and changes in the proportion of pisolites are abrupt. In several areas the uppermost part of the Claymont Clay Bed is a white to light-gray, very sandy, quartzose claystone that grades downward into the typ- ical yellow quartzose claystone. The upper contact of the Claymont, though poorly exposed, appears to range from gradational to disconformable. Near Claymont, in the western part of Irvine Ranch Block 34, the clay has been quarried. There, the typi- cally yellow Claymont Clay Bed grades upward within about 8 em to a gray claystone 0.5 m thick that is over- lain by 0.5 m of sandstone which in turn is overlain by another 1.5 m of gray silty claystone. In this area the top of the Claymont is placed arbitrarily at the base of the lowest prominent sandstone bed. About a hundred meters northeast, a channel-filling sandstone cuts down into the clay, and the gray claystone is absent. The only other place where gray silty claystone grada- tionally overlies the typically yellow Claymont is along the Santiago Truck Trail on the Santiago-Aliso divide. On the prominent ridge just southeast of Baker Can- D24 yon, a bed of conglomeratic sandstone truncates part of the underlying Claymont, indicating a local conformity. From Baker Canyon northwestward toward Black Star Canyon, a dark-gray to black carbonaceous shale and siltstone bed locally overlies the Claymont Clay Bed, which here is very sandy. PETROGRAPHY The Claymont Clay Bed is composed of the clay min- eral kaolinite, as shown by X-ray diffraction study. In thin sections two varieties appear: one yellow brown and apparently isotropic, the other colorless with 6 -a about 0.006. The quartz grains are corroded and re- placed by kaolinite (compare Ross and Kerr, 1931, p. 174, pl. 48¢, d; Listsyna, 1957, p. 862-865). Biotite in various stages of alteration to kaolinite is present. Feldspar is absent. Trace minerals include tourmaline, zircon, and pyroxene. see." "3 wfifiuxl‘ FIGURE 12.- The Claymont Clay Bed (below center) on Gypsum-Fremont Canyons divide; east quarter corner of Irvine Block 34. Claymont Clay Bed is reddish brown, pisolitic, and about 3 m thick. View north. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Thin sections show the variations in the Claymont Clay Bed (table 5). Two are from the lowest 30 cm, one within 60 cm of the base, and three about 2 m above the base, near the top of the clay. One basal sample (fig. 14A, from section E, pl. 4) is almost all yellow- brown or colorless kaolinite, in part pisolitic; the other (fig 13A; near section A, pl. 4) is almost completely pisolitic clay (table 5). A yellowish-brown clay from the lower 60 cm (fig. 13B; section G, pl. 4) is almost all kaolinite (table 5). One section from yellow clay 2 m above the base is almost all kaolin (table 5), and one from the very top of the clay near Claymont (fig. 14b; section C, pl. 4) is about 40 percent kaolinite (table 5). A section from the lower 0.6 m of the clay in the central part of Irvine Ranch Block 114, north of Baker Canyon, 2.7 km from its mouth, is four-fifths kaolinite (table 5). Two thin sections represent the clay in the south- easternmost part of the map area. A yellowish-brown GEOLOGY OF THE SANTA ANA MOUNTAINS D25 clay from the southwest bank of Santiago Creek, oppo- | farther south, is also yellowish brown and is 97 percent site Modjeska, is 72 percent kaolinite (table 5); | yellow-brown to colorless kaolinite (table 5). another section, from the Santiago Truck Trail, still a LJ FIGURE 13.- Photomicrographs of the Claymont Clay. A, Basal part of bed, 60 m east of measured section A (pl. 4). Kaolinite forms _ FigurE 14.- Photomicrographs of the Claymont Clay. A, Basal part 99 percent of rock as pisolites and matrix, plus clastic fragments of bed, measured stratigraphic section E (pl. 4); quartz-free of quartz and altered biotite. P, pisolites. B, Basal part of bed kaolinite, as pisolites and matrix, and highly altered biotite, zir- measured section G (pl. 4), lower 0.6 m of clay. Quartz common con, and iron oxide; P, pisolites. B, Quartz-rich upper part of with uniform distribution in both kaolinite matrix and pisolites; bed, measured stratigraphic section c (pl. 4). Q, quartz; T, tour- opaque minerals few, tourmaline. P, pisolites. maline; O0, opaque minerals; with clay matrix. D26 UNIT D, UPPERMOST SANDSTONE, SILTSTONE, AND CONGLOMERATE,; SERRANO CLAY BED In the type region of the Silverado Formation the strata of unit D directly above the Claymont Clay Bed are similar to those below it and are considered to be nonmarine. One hundred or so meters higher, here and elsewhere north of lower Santiago Creek, strata con- taining moderately well preserved brackish-water and marine fossils overlie the nonmarine beds above the Claymont. Southeast of Black Star Canyon, however, fossils have not been found in this formation. Unit D varies so greatly from place to place that it will be de- scribed under five headings, as follows: type region northeast of Irvine Park; northeast of Irvine Lake; north-central area - Fremont Canyon to the Santa Ana River; northeast of Whittier fault; and area southeast of Black Star Canyon. TypEREkciON NORTHEAST OF IRvint PARK In the type region of the Silverado Formation the first 110 m of unit D above the Claymont Clay Bed is cross- laminated sandstone beds that contain abundant feldspar and biotite. The biotite in some beds has weathered golden yellow; in others it is fresh, black, and shiny. At about 110 m above the Claymont oysters and other brackish-water fossils are present. Several meters higher, the first two of several beds of car- bonaceous shale occur. The uppermost 120 m of calcareous, fine- to medium-grained sandstone is probably entirely marine. Several calcareous beds contain marine fossils but are less resistant to erosion than the underlying strata. Woodring and Popenoe (1945) collected the Paleocene guide fossils Turritella pachecoensis and Perissolax tricarnatus in or near the lower part of these beds, 250 m west of their measured section. NORTHEAST OF IRVINE LAKE Unit D is as much as 430 m thick in this area. As in the type region of the Silverado Formation, the princi- pal coaly bed is about 120 m above the Claymont Clay Bed, and a second carbonaceous shale and lignite bed is about 60 m higher. Poorly preserved marine or brackish-water bivalves and gastropods occur between the lignite beds. Locally these fossiliferous beds are composed almost entirely of shells, and an oyster bed is also present on the ridge immediately north of the mouth of Black Star Canyon. A ridge 400 m east of the type section is formed by a completely silicified sandstone bed 6 m thick. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA During the latter part of the 19th century the car- bonaceous shale and lignite beds were extensively prospected and locally mined for fuel. One of the largest operations was located at the old Santiago Coal Mine, where a total of 10 abandoned shafts attest to the mining activity in the area. These mines all appar- ently were developed in the upper of the two car- bonaceous beds. NORTH CENTRAL AREA - FREMONT CANYON TO THE SANTA ANA RIvER The beds of unit D in this area dip irregularly north- west in a section that is at least 180 m thick. Unit D here is mostly light-gray to buff sandstone. For a meter or so above the Claymont Clay Bed, the sandstone is very coarse grained, locally mottled red and white, and contains many golden-yellow flakes of kaolinite after biotite. A little higher in the section, finer grained sandstone beds contain greenish-black to black biotite that is locally so abundant that the rock resembles bio- tite schist. Lenticular beds of coarse-grained gritty sandstone as much as 2 m thick show large-scale crossbedding. Quartz is the principal mineral in most of the sequence; feldspar is present but minor. The matrix is clayey. Dark-brown concretions are locally present. Two, possibly three oyster beds occur about midway through the section. A thin section of a sample from the lowest of these beds is mostly fine-grained or coarsely crystalline calcite but includes many corroded quartz grains and some feldspar, both sanidine and oligoclase. Followed north, the underlying Claymont Clay Bed seems to disappear about 2 km south of the mouth of Coal Canyon. In this northern stretch, north- east of BM 1063, the lowest recognized oyster bed is slightly less than 90 m above the base of the Silverado Formation. In the eastern part of Irvine Ranch Block 27, 2.5 km south of the mouth of Coal Canyon, above the highest oyster bed, a local conglomerate 1 to 5 m thick marks the change from coarse-grained buff sandstone below to the finer grained greenish-gray micaceous sandstone typical of the upper, marine part of the Silverado For- mation. About 2 km farther north, 180 m northwest of BM 1063, a similar conglomerate that may be at the same horizon (Woodford and Gander, 1977) provided the lowest known accumulation of the rhyolitic and other metatuffs called Poway-type clasts by Woodford and others (1972). The composition of the conglomerate is: Rock type Percent Poway lype lu 59 As:... ._ cl cence nee Pucca presses s 9 clo noc sise 8 Granite and quartz monzonite aplite ___________ 9 GEOLOGY OF THE SANTA ANA MOUNTAINS Percent Rock type Granite pOrDRYIY 2.2clc cell nec onesie aiid 6 Granite SNOISG bak on 5 Granodiorite and quartz monzonite .___.___.___.._ 3 SARUSLONC -~ oll re dec ei ena bebe nen 1 The upper sandstone beds are well exposed at the south edge of the Riverside Freeway in Santa Ana Can- yon, 260 m south and 6.1 km west of the northeast corner of the Black Star quadrangle, where they con- tain marine mollusks (locally F84). Along and just south of Santa Ana Canyon the uppermost fossiliferous marine part of the Silverado Formation is overlain by the basal conglomerate of the Eocene Santiago Formation. At the top, 505 m north- west of BM 1063, a diagnostic Paleocene fossil as- semblage was collected (locality F86). Farther south- west, in a tributary of Gypsum Canyon, a Paleocene shell bed (locality F88) was eroded slightly before sandstone at the base of the Eocene section was depos- ited. NORTHEAST OF WHITTIER FAULT In an east-striking fault slice at the northeast corner of the map area, a strip of the Silverado Formation 3 km long dips steeply north at places but is mostly over- turned so that steep southward dips are the most prev- alent. The section is at least 250 m thick. Its lower part is composed of fine- to coarse-grained gritty con- glomeratic sandstone beds that are white to yellowish brown, greenish red, and reddish brown. Biotite is abundant. These beds resemble those of unit D just above the Claymont Clay Bed in more complete se- quences. Overlying them are interbedded buff sandstone and conglomerate, with poorly preserved oysters near their base. Locally the conglomerate con- tains reddish volcanic clasts like those in the local con- glomerate above the oyster beds in the north central area. The micaceous sandstone and interbedded siltstone above this conglomerate locally contain poorly preserved marine mollusks. In a small fault sliver 300 m south of the west end of the strip, a diagnostic marine molluscan fauna is present (locality F85). In ridges at the east end of the strip, east of Fresno Canyon, interbedded white to buff coarse-grained sandstone, gray and yellowish-gray siltstone, and buff conglomerate grade upward into poorly sorted quartz- feldspar-biotite pebbly sandstone, in part well cemented. Just east of the map area these beds grade upward into a thick sequence of clay-rich beds not ex- posed elsewhere in the Silverado Formation (Gray, 1961), which contain well-preserved Turritella pachecoensis, a strongly noded form (locality F83). D27 AREA SOUTHEAST OF Brack STAR CANYON The Silverado Formation is continuously but poorly exposed from the mouth of Black Star Canyon south- eastward to the east edge of the map area. Outcrops on the prominent ridge 520 m southeast of Baker Canyon indicate the general character of the formation north of Silverado Canyon. In these outcrops the Claymont Clay Bed is overlain directly by about 1 m of unit D clayey conglomeratic sandstone that contains abundant golden-yellow kaolinite after biotite, whereas im- mediately northwest of Baker Canyon unit D car- bonaceous shale rests directly on the clay. Above the sandstone is about 20 m of buff poorly sorted coarse- grained biotitic sandstone and interbedded sandy siltstone which ranges in color from greenish gray to maroon. Gradationally overlying these varicolored beds is about 40 m of soft greenish-gray micaceous fine- to medium-grained sandstone and interbedded siltstone and sandy siltstone. Gray calcareous concretions, weathered dark brown, are common in this sandstone- siltstone sequence, but none of these contain evident fossils, though this interval is similar lithologically to the marine sequence north of Irvine Park where the concretions are fossiliferous. This concretionary unit is overlain by about 10 m of poorly sorted clayey sandstone with a waxy. clayey matrix that is more abundant in the upper part. The lower part contains relatively fresh biotite; biotite in the upper part ap- pears as books and flakes of pale greenish-gray mica and is more altered and weathered. The entire ridge section is about 75 m thick and presumably is chiefly nonmarine. The ridge section described above includes the Ser- rano Clay Bed, which in turn is overlain by about 120 m of strata assigned to the upper part of the Silverado Formation. This sequence is traceable to the southeast corner of the map area. The Serrano Clay Bed is about 1 m thick and is composed of about 50 percent un- sorted and randomly distributed angular quartz grains in a matrix of light-gray to white clay. Unlike the Claymont Clay Bed, it is soft and plastic. Locally it is mottled pink, maroon, and purple. It is overlain by a thin bed of hard white quartz-rich and clayey fine- to medium-grained sandstone, in turn succeeded by 0.3 m of black laminated carbonaceous shale. Above the Ser- rano the uppermost 120 m of the Silverado Formation is gray and buff sandstone interbedded with some siltstone beds as much as 5 m thick. Fragments of silicified wood are locally common in the lower part of this sandy sequence. Near the upper contact, on the southeast side of Modjeska Road near its intersection with the Santiago Truck Trail, a massive white bed of sandstone contains a few scattered pebbles and cob- bles. D28 AGE AND CORRELATION Molluscan assemblages of the Silverado Formation generally consist of few species. Three assemblages contain genera suggesting brackish water (localities F97, 98, 99). The following marine forms are common in the Santa Ana Mountains area: Turritella pachecoen- sis Stanton, strongly noded form, Turritella pachecoen- sis Stanton, and Cucullaea cf. C. mathewsonit Gabb. Other species are cited in the section "List of Megafos- sils." Woodring and Popenoe (1945) considered their rather meager fauna from the area near Irvine Park to indicate a Paleocene age for the Silverado Formation. The presence of the typical Paleocene forms Brachy- sphingus cf. B. lyratus Gabb, Turritella pachecoensis Stanton, strongly noded form, and Cucullaea ef. C. mathewsonit Gabb in our collections from the upper part of the Silverado substantiates the Paleocene age assignment. The age of the lower part of the Silverado has not been determined on the basis of the brackish- water mollusks, but because it grades upward into and presumably intertongues with the marine strata and rests unconformably on Upper Cretaceous rocks, it is assigned a Paleocene age supporting the conclusion of Woodring and Popenoe ( 1945). EOCENE SERIES SANTIAGO FORMATION Fossiliferous Eocene strata in the Santa Ana Moun- tains were first described by Dickerson (1914) and as- signed by him to the Tejon Formation, the type locality of which is on the northeast side of the San Andreas fault near Fort Tejon, 160 km to the northwest. English (1926) followed the same usage and mapped several small areas of Eocene rocks between Santiago Creek and the Santa Ana River. Woodring and Popenoe (1945) measured stratigraphic sections and identified fossils from the Eocene strata in several parts of the northwestern Santa Ana Mountains. They proposed the name Santiago Formation for these strata, which they correlated with the upper half of the California Eocene. The type region of the Santiago Formation is about 1 km northeast of Irvine Park, on the north side of San- tiago Creek. Because we were unable to map an upper boundary of marine strata in the type region, we in- clude in the Santiago about 600 m of massive buff to yellow sandstone that underlies the basal conglomerate of the undifferentiated Sespe and Vaqueros Forma- tions. Presumably, the massive sandstone in the upper part of the Santiago is nonmarine; silicified wood commonly is present in it. The Santiago Formation GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA throughout the map area rests on the Silverado Forma- tion (fig. 15). At the southeast, where both are proba- bly nonmarine, separation of the two is especially dif- ficult. The Santiago Formation occurs in relatively small areas, most of which are confined to three strips. The northeasternmost strip extends along the south side of the Santa Ana River; the second extends from the river southwest to Irvine Park; and the third lies along San- tiago Creek from Irvine Park to the southeast corner of the map area. Other small areas of outcrop are present in the southwestern foothills. Subsurface data are meager, largely because most wells bottom in beds above the Eocene section. Rubicon Oil Co. well, Wilcox No. 1, north of Burruel Ridge reached Eocene rocks as did Shoreline Oil Co. well, Pinkerton No. 1, southeast of Orange. Texas Co. well, A-13-1, 3 km west of Anaheim, 8 km west of the map edge, probably pene- trated at least 100 m of the formation (Woodring and Popenoe, 1945: Schoellhamer and Woodford, 1951). The formation is absent from Amerada Petroleum Corp. well, Irvine No. 63-1, southeast of Tustin, and, in the same area, from Shell Oil Co., Irvine Core Holes Nos. 4 and 5. It probably is present in the subsurface near El Toro and crops out again farther southwest in the San Joaquin Hills (Vedder and others, 1957; Ved- der, 1975). The Santiago Formation may be thickest at the west. The westernmost unfaulted outcrop sequence is 820 m thick in the type region. Ten km farther west, between Orange and Santa Ana, the Shoreline Oil Co. well, Pin- kerton No. 1, bottomed in Eocene strata after penetrat- ing 340 m of the formation. Northeast of the type re- gion, near the head of Gypsum Canyon, the section is estimated to be about 250 m thick, and in the far northeast, north of the Whittier fault, a measured sec- tion is about 205 m thick. In the east-central area bet- ween Irvine Lake and the mouth of Black Star Canyon, the thickness is about 235 m and in the extreme south- east the formation is only 90 m thick and may be en- tirely nonmarine. The lithology of the sedimentary rocks in the San- tiago Formation suggests that their bulk was derived chiefly from the bedrock complex that crops out a few kilometers to the east, that most of the sandstone and siltstone consists of the products of the perhaps direct disintegration of basement rocks, but that the con- glomerate is a concentrate of the more resistant ele- ments in it, plus quartzite and metatuff of possibly dis- tant origin. Crossbedding, measured at 79 points in the Eocene outcrops close to Santiago Creek between the mouth of Fremont Canyon and Modjeska indicate current direc- tions fairly close to due west (Davis, 1978). GEOLOGY OF THE SANTA ANA MOUNTAINS D29 STRATIGRAPHY AND LITHOLOGY Santa Ana Canyon north of the Whittier fault, the con- BASAL CONGLOMERATE glomerate thickens to a maximum of at least 68 m and In the type region of the Santiago Formation and | contains clasts as much as 30 or 35 cm in diameter. northeastward to the head of Gypsum Canyon, the | Southeast from the type region, along Santiago Creek, basal conglomerate is only 1.5 to 3 m thick. Sandstone | the thickness is variable. is present at the base at the head of Gypsum Canyon The pebbles and cobbles in the type region and east rather than conglomerate. Along the south side of | or southeast of it consist of as much as 40 percent FIGURE 15.- Contact between basal conglomerate (at hammer) of Santiago Formation and sandstone of Silverado Formation. On south side of Santa Ana Canyon (now Riverside) Freeway just east of unnamed canyon in Irvine Block 30. View south. D30 quartzite and include vein quartz, varicolored volcanic rocks, pale quartz plutonite and gneiss, hard sandstone, and metaconglomerate. Few if any pebbles or large clasts are of rock types that could have been derived from the Bedford Canyon Formation. The basal conglomerate in and near Santa Ana Can- yon, on both sides of the Whittier fault, is exceptional in composition as well as in thickness, with many clasts of siliceous metatuff (Woodford and others, 1968). Woodford studied a sample of 100 clasts larger than 2.5 cm diameter from south of the Whittier fault; 37 were studied in thin section and 16 analyzed chemi- cally. Their compositions are given below. Almost all these clasts were quartz rich, and their textures make them resist disintegration. Farther west, between Coal and Gypsum Canyons, the basal conglomerate is much thinner, and the percentage of quartzite clasts much higher. Rock type Gray or reddish rhyolitic and rhyodacitic matatuff ___. 42 Granite and soda 16 Quartzite ( 3 /..... Quartz monsonite 00sec el. llis. Granite porphyry .._... Granite porphyry gneiss .__________._____________ Quartzose gneiss and schist .____________________ CL L; LLL Sandstone and metasandstone ._________.__.._.. Nontuffaceous metarhyolite; andesite; aplite; granodiorite porphyry; rhyodacite; quartz monzonite gneiss; granodiorite gneiss ____________________ Number m a Or No > o> co STRATA ABOVE BASAL CONGLOMERATE Above the basal conglomerate the Santiago Forma- tion is mostly gray to buff micaceous feldspathic sandstone interbedded with subsidiary siltstone. Carbonate-cemented sandstone concretions are 5 cm to 1 m in diameter; some contain marine mollusks, others, plant remains. Silicified wood is common in the higher, probably nonmarine, section. PETROGRAPHY Nine samples of the Santiago Formation were point counted in thin section. Two are from basal sandstone: one from the type region has clastic grains up to 6 mm across, and one, probably nonmarine, from the Santiago-Aliso divide at the far southeast has clastic grains up to 1.68 mm across (table 6). Two sandstone samples are from the lower third of the formation: one from the south side of Santa Ana Canyon between Coal and Gypsum Canyons has clastic GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA TABLE 6. -Petrography of the Santiago Formation Volume Rock type Composition percent Comments Basal sandstone Sandstone Quartz ........................ 12 (type _ Andesine. {28 region). Orthoclase .. 1 .s 2 Epidote and sphene wel Rock fragments .. ..11 _ Sedimentary, plutonic, and volcanic rocks. Organic remains.........._.. 27 _ Calcareous algae, foraminifers, and shell fragments. MAH IE Ardenne eed occ 38 _ Calcite cement. Sandstone Quartz... (prob- - Andesine.. ag Orthoclase..... non- Rock fragments... 18 _ Sedimentary, plutonic, and volcanic rocks. marine). Opaque minerals. __10 Biotite and chlorite........... 8 Lower third Sandstone Quartz........................ 20 (Santa - Plagioclase . s Ana Orthoclase...... Canyon). Rock fragments... Biotite and chlori Opaque minerals Epidote and muse Matrix«......_.. Sandstone Quartz........................ 54 (Little _ Andesine . 21 Joaquin Orthoclase... Valley). Andesine and untwinned oligoclase/andesine. Sedimentary, metamorphic, plutonic rocks. Calcite cement, replacing original clayey- chloritic matrix. And untwinned oligoclase/andesine. Sedimentary, plutonic, and volcanic rocks. Micaceous, altering to clusters of minute epidote. Biotite and chlorite........... 8 Muscovite....... 1 Opaque mineral 3 Epidote..... 1 Sphene, ru 1 Middle third Sandstone Quariz........................ 18 (Gypsum Andesine.. Canyon). Orthoclase Biotite........ Rock fragments Sedimentary rocks. roues reba 63 _ Calcite cement, replacing original clayey- micaceous matrix. Sandstone Quartz....._.._...._.._._..... 35 (Silver- Andesine.. 15 ado Orthoclase ... #k ; Canyon). Rock fragments 4 _ Sedimentary, plutonic, and volcanic rocks. fotite ...... l Muscovite ...... Trace Opaque minerals. 2 Epidote .............. 12 Sphene (and rutile?) ___ Trace Math ix eset en S.. e 39 _ Calcite cement. Upper third Sandstone Texture: clastic grains up to 1.34 mm across. anta An untwinned oligoclase/andesine. Ana Canyon). Sedimentary, metasedimentary, and volcanic roc Calcite cement replacing detrital matrix. Sandstone (Silver- Untwinned oligoclase/andesine. ado Canyon). Sedimentary, plutonic and volcanic rocks. Calcite and clay. Sandstone San- tiago- _ Or Aliso Rock fragmen Sedimentary and plutonic rocks. divide). Biotite and chio Clay. GEOLOGY OF THE SANTA ANA MOUNTAINS grains up to 1.47 mm across, and the other from Little Joaquin Valley has clastic grains up to 0.67 mm across (table 6). Two probably marine sandstone samples are from the middle third of the formation: one from near the head of Gypsum Canyon has clastic grains up to 0.67 mm across, and the other from the north side of Silverado Canyon has clastic grains up to 0.64 mm across (table 6). Two sandstone samples, the first probably nonmarine and the second surely so, are from the upper third of the formation. One from the south side of Santa Ana Canyon west of Coal Canyon has clastic grains up to 1.34 mm across, and the other from the south side of Silverado Canyon has clastic grains up to 1.54 mm across (table 6). Another nonmarine sample from the Santiago-Aliso divide 3 m below the top of the forma: tion has clastic grains up to 1.34 mm across (table 6). SUBSURFACE DISTRIBUTION Subsurface data on the Santiago Formation are lim- ited to a few wells. North of Burruel Ridge, electric-log characteristics of the Rubicon Oil Co. well, Wilcox No. 1, indicate that at 1,762 m the hole passed from prob- able basal conglomerate of the undifferentiated Sespe and Vaqueros Formations, 23 m thick, into an alternat- ing sequence of siltstone and fine-grained sandstone indicative of the Santiago Formation that extends to the bottom of the hole at 1,928 m. Ditch cuttings below about 1,838 m are reported to contain foraminifers of Eocene age. The Texas Co. well, Ragan (NCT-1) No. 1, north of Santiago Creek near its debouchure from the mountains, passed from probable basal conglomerate of the undifferentiated Sespe and Vaqueros Formations into finer grained beds of the Santiago Formation at a depth of 1,100 m. The base of the Eocene section here 'is missing because of normal faulting. The electric log and ditch samples indicate unfossiliferous fine-grained sandstone and siltstone interbedded with medium- to coarse-grained gray sandstone for the upper part of the unit. About 2 km southeast of Orange, Shoreline Oil Co. well, Pinkerton No. 1, passed from red beds of the undifferentiated Sespe and Vaqueros into coarse gray to black sandy siltstone and hard gray sandstone of the Santiago Formation at about 760 m depth. Eocene foraminifers and mollusk fragments were reported below 765 m. The thick nonmarine sequence of the Santiago that crops out several kilometers to the east was not recognized in the Pinkerton well. This sequence may not be present in the subsurface of the Los Angeles basin, or its equivalent there may have been considered part of the undifferentiated Sespe and Va- queros Formations. D31 AGE AND CORRELATION The Santiago Formation contains fairly large mollus- can and foraminiferal faunas. The fossils are mostly limited to the fine-grained concretionary strata in the lower part and to the basal sandstone and conglomer- ate where those are exposed north of Irvine Park. Foraminiferal faunas. - Samples from the type region and from a quarry near the head of Gypsum Canyon (same as megafossil locality F100) were examined for foraminifers by M. C. Israelsky, who supplied the fol- lowing report: Foraminifers positively identified from the type region include: Amphistegina californica Cushman and M. A. Hanna, Cibicides memasteri Beck, and Haplophrag- moides nonionelloides Israelsky. About 60 m of fine- grained sandstone of the lower part of the Santiago Formation from the quarry yielded foraminiferal faunas that are similar throughout the section. These include Haplophragmoides nonionelloides Israelsky, Guadryina (Pseudogaudryina) coalingensis alata Is- raelsky, Massilina decorata Cushman, Amphimorphina californica Cushman and McMasters, Gyroidina simien- sis Cushman and McMasters, Cibicides memastersi Beck, and C. pseudowellerstorffi Cole. Woodring and Popenoe (1945) considered the mol- luscan fauna of the lower part of the Santiago Forma- tion to be similar to that of the La Jolla Group farther south (Hanna, 1927; Kennedy and Moore, 1971). The benthic foraminifers as well as the mollusks from the lower part of the Santiago Formation in addition to being similar to those of the La Jolla Group are also similar to those of the upper part of the Llajas Forma- tion of the Ventura Basin, and the Domengine Forma- tion of central California. These strata traditionally have been called middle Eocene by most California paleontologists. The identified benthic foraminifers from the lower part of the Santiago Formation are re- ferable to the upper part of the Ulatisian Stage of Mal- lory (1959), and therefore may be correlated with the Discgaster sublodoensis nannoplankton zone (Poore, 1976). EOCENE(?) TO MIOCENE SERIES UPPER EOCENE(?) TO LOWER MIOCENE SESPE AND VAQUEROS FORMATIONS, UNDIFFERENTIATED The Santiago Formation is overlain conformably by a varied sequence of interbedded marine and nonmarine sandstone and conglomerate assigned to the undif- ferentiated Sespe and Vaqueros Formations. The Sespe Formation was defined by Watts (1897) from its type D32 locality along Sespe Creek, in the western part of the Transverse Ranges, 160 km northwest of the Santa Ana Mountains. The "Vaquero Sandstone" (Vaqueros For- mation) was defined by Hamlin (1904, p. 14) from its type locality west of King City in the Santa Lucia Range, 420 km northwest of the Santa Ana Mountains. Both formations are present at many places in the Transverse Ranges, and also in the San Joaquin Hills southwest of the Santa Ana Mountains (Vedder and others, 1957). Although the marine Vaqueros com- monly overlies the nonmarine Sespe in most of these areas, marine and nonmarine strata intertongue in the central Santa Monica Mountains as well as in the Santa Ana Mountains. The interbedding of Sespe and Vaqueros Formations in the Santa Ana Mountains was first recognized by English (1926, p. 23-24). The Vaqueros Formation con- tains the shallow-marine Turritella inezana santana fauna and in general grades westward and southward into finer grained, deeper water sedimentary deposits. The undifferentiated Sespe and Vaqueros Formations are exposed over a larger part of the northern Santa Ana Mountains than any other Tertiary or Mesozoic rock unit. Nearly continuous outcrops form an are ex- tending from the northeast to the southeast corners of the map area. Subsurface data in the area west of the outcrops are meager, for only a few wells have been deep enough to penetrate the undifferentiated Sespe and Vaqueros. However, these strata are probably pre- sent everywhere in the subsurface section beneath the western part of the map except in the vicinity of the Amerada Petroleum Corp. well, Irvine No. 63-1, and southeast of the northeast-trending fault between the Shell Oil Co. wells, Irvine Coreholes No. 4 and 5 (Yerkes and others, 1965, fig. 8). Although reddish-stained outcrops generally seem to predominate in natural exposures of the combined unit in the Santa Ana Mountains, detailed examinations re- veal that most beds are gray or pale buff rather than the deep reddish-brown hues characteristic of the Sespe Formation in its type locality. Beds containing marine fossils weather pale gray. The undifferentiated Sespe and Vaqueros Formations range in thickness from 300 to 900 m-thinnest near Weir Canyon, north of Santiago Creek and at about the midpoint of the outcrop arc, and thickest in the Peters Canyon area south of Santiago Creek. There are three principal lithologic subdivisions: (1) a basal conglom- erate, present wherever the base is exposed, that ranges from a few tens to a hundred meters or so thick; (2) an overlying sandstone and conglomeratic sandstone which forms the main part of the unit; and (3) an upper conglomerate, that is about 200 m thick, present locally in northern part of the area. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA The marine strata are limited to the southwestern part of the outcrop arc, southwest of a line extending east along the south side of Burruel Ridge, then cross- ing Santiago Creek at the Irvine Lake dam, and follow- ing the southwest side of Limestone Canyon to the east side of the slide area just south of The Sinks. The southeasternmost marine fossil locality, F139, is in the upper part of the section about 300 m above the base. The single locality that yielded terrestrial mammal re- mains is about 200 m above the base. Detailed correla- tions within the undifferentiated Sespe and Vaqueros, from the southern area north across Santiago Creek, are uncertain because of the limited outcrops and ab- rupt facies changes. STRATIGRAPHY AND LITHOLOGY BASAL CONGLOMERATE The buff, feldspathic, medium- to coarse-grained pebbly sandstone that occurs in the lowest part of the undifferentiated Sespe and Vaqueros Formations and in the upper part of the underlying Santiago Forma- tion, lithologically very similar in some areas, makes recognition of the base of the undifferentiated Sespe and Vaqueros difficult. The contact is placed at the base of a sharply bounded dark-colored conglomerate (fig. 16), commonly 2 to 15 m thick and made up of closely packed, smooth pebbles and cobbles in a gray sandy matrix. In the northeast corner of the map area, north of the Whittier fault and east of Fresno Canyon, the thickness increases to about a hundred meters, and boulders a meter or so in diameter are numerous and are the largest anywhere in this basal conglomerate. The lithology here contrasts sharply with that of the marine sandstone in the underlying Santiago Forma- tion. The pebbles and cobbles in the basal conglomerate were sampled by Woodford and others (1968) in three places. One is at the edge of the Riverside Freeway on the south side of Santa Ana Canyon, 5,800 m west of long 117°37'30"". The sample of 300 clasts, each iden- tified in thin section, is made up as follows: Rock type Percent Poway type (rhyolitic and other silicious metatuffs) .____._.___._________._.._ 54 Andesite and other volcanic rocks ____.______._.... 17 Quartzite and vein 11 Metamorphic roCk$ 6 CTAYWEACKE -.. :o cen rico eosin cons sa anea mele 6 Aplite } 3 Cranite porpHYyTY ll. Cole dolu ss 2 Granite. 1 The second locality is in Peters Canyon northeast of the lower dam. A sample of 100 clasts, each determined in thin section, is made up of: GEOLOGY OF THE SANTA ANA MOUNTAINS D33 Rock type Percent The third locality is on the Bolero road just west of Pow ype a upper Santiago Creek. The hundred clasts, each Quartz1te 3 examined in thin section, include: Crane ::.. ..J. / il e ou se tedecs 6 Volcanic pOrPhYTY c ccc .nl. ecen arenite. 5 Rock type Percent épliFe g Poway type (soda rhyolite or similar Anglssé"" weed 9 MELSTUTT) H! sere nes us et ite 23 Gn °" ek' """""""""""""""""""""" { Unmetamorphosed andesite or other -- pani ane non omar ang enone eo volcanic rocks (half are tuff) .____._____________ 18 Quartzite_ .... ln 18 Of the 71 specimens of the general Poway type, 21 graglte ------- a 9 lack large quartz grains and have a completely recrys- Gan stone f s ) Th rd ranite or quartz-rich gneiss.... 7 tallized ground mass (Peters Canyon type). The sandy iaa ran [f_ ¥ matrix at the Peters Canyon locality is about as follows: dioerite ! .rt cic g [ Aplite or pegmatite 4 Granite o.: 2 Component grains Volume percent Mylonite ___________________________________________ 2 (CraROUIOLILE-1;- cre- ie crece 1 3:1? zfxfic-ngc-l; """"""""""""""""" 32 Vein or pegmatite quartz......_..._..._....__._.. 1 Potassium - arre tne § {giggle Soaps 18 The 500 pebbles and cobbles studied in thin section Guartzite 3 show: (1) an abundunce of siliceous metatuff and (2) a QuUaTtZ 20222220000. 20 2. oe clasa sill. 2 geographic variety of the rock types in the basal con- FIGURE 16.- Sharply bounded, dark-colored basal conglomerate (middle of photograph) of the undifferentiated Sespe and Vaqueros For- mations overlying the Santiago Formation, east of Gypsum Canyon. Thickness of the undifferentiated Sespe and Vaqueros shown is about 30 m. View north. D34 glomerate. In general, the assemblages are composed predominantly of rhyolite or soda rhyolite metatuff, quartzite, and granite or soda granite. The rarity of quartz diorite or granodiorite similar to that of the Cre- taceous batholith to the east is a striking feature. SANDSTONE AND CONGLOMERATIC SANDSTONE The main part of the undifferentiated Sespe and Va- queros Formations is composed of beds of reddish, gray, and buff to white feldspathic sandstone that con- tains numerous but scattered or isolated pebbles and cobbles. Many lenses of conglomerate are also present, however. In the northeast corner of the map area the sequence above the basal conglomerate is mostly yel- low to white clayey feldspathic biotitic coarse-grained to conglomeratic sandstone, with a few brownish-red earthy sandstone layers, as well as stringers of pebbles and cobbles. Farther west, around Gypsum Canyon, the sandstone and conglomeratic sandstone is indistinctly bedded, yellowish-gray, tan, and buff sandstone, in part with a clayey matrix (upper part of fig. 16). Quartz is abundant, feldspar common, and crinkly bio- tite evident. Lenses of gravel include clasts as much as 0.3 m in diameter. At the top, the sandstone is poorly sorted, pinkish gray, and conglomeratic. Many frag- ments of granitic rock are contained in it. South of Burruel Ridge and north of Santiago Creek, around Weir Canyon, marine fossils are present in well- bedded, calcite-cemented, greenish-gray layers, inter- bedded with probable nonmarine strata similar to those around Gypsum Canyon. The thickest section of the sandstone and con- glomeratic sandstone is southwest of upper Santiago Creek, on both sides of Loma Ridge (pl 3, structure sections R-S and U-V), where the combined marine and nonmarine beds are about 900 m thick. The lower beds of the undifferentiated Sespe and Vaqueros Formations above the basal conglomerate are well exposed on the east limb of the synclinal bowl along upper Santiago Creek (fig. 17), where they are unfossiliferous, contain numerous red beds, and probably are wholly non- marine. These beds are perhaps entirely pre-Miocene in age. The upper beds of the sandstone and conglomeratic sandstone are fairly well exposed in an are around Loma Ridge, from Peters Canyon and Rattlesnake Can- yon to upper Limestone Canyon. These beds are alter- nating unfossiliferous yellowish, reddish, and greenish-gray sandstone and conglomerate, with thin interbeds of green and red sandy siltstone, and fos- siliferous marine greenish-gray to white sandstone. The uppermost beds of the section are entirely marine, up to 1.5 m thick, calcareous, and contain Turritella in- ezana santana and many other mollusks as well as echinoid fragments. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA In the vicinity of Bolero Lookout on the west side of upper Santiago Creek, a reddish-brown sandstone in the upper beds of the undifferentiated Sespe and Va- | queros Formations contains the guide gastropod Rapana vaquerosensis imperialis (locality F139). Not far away, in pinkish-gray sandstone, bone fragments of a late Oligocene(?) camelid associated with unworn shark teeth and ray teeth (locality V1) were found just below the top of the unit. Thin sections of sandstone in Gypsum Canyon, repre- senting the sandstone and conglomeratic sandstone from bottom to top, show the following ranges: Component grains Volume percent ccie 52-66 Potassium feld@par cic llc else 2-28 ~ ll cell :e oan saree 3-18 Volcanic TOCK 2-2 lleno econ rene 0-17 -c.. ccc ii seen 2-7 T. ellen cnc cie ean ene 2-6 Conglomeratic layers in the sandstone of the main part of the unit were studied by Woodford and others (1968) at three locations. Clasts over 2.5 ecm in diame- ter were similar to those in the basal conglomerate but show the following ranges: Rock types Percent POWAV IYDC ::... 12-66 Andesite and other volcanic TOGKs cl 5-22 Graywacke and other sedimentary 1-19 Quartz and vein quartz 3-17 Quartz plutonite, mostly granite ________________ 6-16 ONCE .L lll? codec. e 12-13 APTC: orci reel een 2-5 UPPER CONGLOMERATE On the east side of Gypsum Canyon, just south of the Santa Ana River, the sandstone and conglomeratic sandstone grades abruptly upward into an upper mas- sive conglomerate. Locally present is a solid mass of very crudely stratified, gray, closely packed, indurated gravel 150 to 180 m thick. The whole mass is the site of the Star Quarry of the Owl Rock Products Company. A fault striking N. 35° E. splits the mass, the northwest- ern block apparently being downdropped slightly to the northwest. The gravel southeast of the fault is un- cemented, whereas drilling and blasting are required to prepare the gravel for easy excavation in the quarry to the northwest of the fault. The conglomerate at the Star Quarry is composed chiefly of subangular clasts 3 to 18 ecm in diameter in a sparse coarse gray sandy matrix (Woodford and others, 1972). A collection of 100 of these clasts, taken in 1975 southeast of the fault, was studied in thin sec- tion. Major rock types included: GEOLOGY OF THE SANTA ANA MOUNTAINS Rock types Percent Poway type (metatuff)} _._... 49 (3 with piemontite) Q ..o iss icu enne 16 Recrystallized biff? . ened Poway type Epidote-rich metamorphic rock ______._______._._. Alkall AGILE desk Quartz monzonite Tuffaceous SANUSLONE Dacite Granite porphyty :..... SACE IIIA ALCL e ia Tourmaline-quartz MaSKIEC --..: neram can Metasandstone, Bedford Canyon(?) Formation -------------- Ite dne cess. Feldspar - qUATHE TOCK ne nece en CTanite ENOISE. - el erie ene cee eck Hoi ho bo ho ho Go A Of oagerldet k- D35 The presence of probably more than 50 percent of Poway-type clasts is noteworthy and probably charac- teristic of this conglomerate. It generally is massive rather than well bedded. A very few short, thin lenses of feldspathic, biotitic sandstone demarcate the bed- ding. The few evident depositional features are sheets of fairly flat imbricated cobbles and sandstone crossbeds; each set suggests a source to the northeast. In 1971-72 progressive eastward excavation of the Star Quarry passed through a lens of very coarse con- glomerate 10 or so meters thick, probably somewhat above the middle of the section in the quarry. Hun- dreds of boulders are 1 m or more in diameter, and many exceed 2 m. Some of these are smooth and ellip- soidal. The largest clast measured is a red Poway-type rock 198 cm long and about half that wide at its nar- rowest. Nearly 50 percent of the boulders, including all FiGURE 17.‘- Lower beds of the undifferentiated Sespe and Vaqueros Formations - reddish strata (upper left), creamy white strata (lower right). Top of hill (left) is about 60 m above stream bed. View west across Santiago Creek from Black Star Canyon Road. D36 the very large ones, are rhyolite or soda rhyolite tuff of Poway type, many of them bright red with piemontite. The next commonest kind of big boulder is smoky-gray perthitic alkali granite with biotite. Boulders of gneiss and clear glassy pegmatite quartz (rarely with one flat face covered with biotite) are fairly common. No bou! ders of quartzite were seen. The granite is nearly iden- tical to a perthitic granite or syenite found recently in the basement complex of the northwestern San Ber- nardino Mountains; both bedrock and boulders have radiometric ages near 170 m.y. (Terry Davis, oral commun., 1977). UPPER CONTACT The contact between the undifferentiated Sespe and Vaqueros Formations and the overlying Topanga For- mation usually is easily recognized where the basal beds of the Topanga are fossiliferous conglomerate. The upper beds of the undifferentiated Sespe and Va- queros, consisting of greenish-gray sandstone and silty sandstone and pinkish and reddish-brown sandstone, contrast sharply with the overlying buff and tan mas- sive conglomeratic sandstone of the Topanga. No evi- dence of an angular discordance between the Topanga and underlying strata was found in the map area. The Topanga rests on various rock types of the Sespe and Vaqueros, probably as a result of changes from marine to nonmarine deposition within the Sespe and Vaqueros rather than of erosion prior to deposition of the To- panga. The contact between the Topanga and the Sespe and Vaqueros is a disconformity. In the hills east of El Modeno, the basal conglomerate of the Topanga is either missing or unrecognizable because of poor expo- sures, and the top of the Sespe and Vaqueros is placed at the top of the highest red beds. Only a short distance above this horizon, a molluscan fauna (F162) typical of the Topanga is present in fine-grained sandstone and: siltstone; mollusks typical of the Sespe and Vaqueros (F140) are present below the contact. On Loma Ridge south of Irvine Lake, the Sespe and Vaqueros are un- conformably overlain by well-laminated siltstone of the Puente Formation. Southeast of this area the Topanga again is present above the Sespe and Vaqueros. SUBSURFACE DISTRIBUTION Well data indicate that the undifferentiated Sespe and Vaqueros Formations are present in the area north of Burruel Ridge, in the vicinity of Orange, and south- eastward to the fault between the Shell Oil Co. Irvine Coreholes No. 4 and No. 5 near El Toro Air Station. Throughout this lowland area the lithology of the Sespe and Vaqueros is similar to that in outcrop and consists of alternating greenish-gray, red and reddish-brown sandstone and conglomerate. North and west of Bur- GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA ruel Ridge, the Sespe and Vaqueros are overlain by the Topanga Formation, whereas in the area southeast of Orange, sandy strata of probable Pliocene age directly overlie the Sespe and Vaqueros (structure sections L-W, E-L, and L-P, pls. 2,3), and both the Topanga and Puente Formations are absent at the unconformity. A still older unconformity in this same area was revealed by the Shell Oil Co. corehole Irvine No. 4. The Sespe and Vaqueros in that well rest unconformably on the Williams Formation of Late Cretaceous age (structure section T-X, pl. 3). Northwest of Orange, deep wells have penetrated varicolored sandstone questionably as- signed to the Sespe and Vaqueros sequence in an ex- tensive area basinward from the Santa Ana Mountains. The northwesternmost of these is in the vicinity of the Leffingwell oil field near lat 32°55" N., long 134°00' W. (Yerkes and others, 1965, fig. 8 and pl. 4; Yerkes, 1972; pl. 2). AGE AND CORRELATION Fossils have not been found in the nonmarine lower beds of the undifferentiated Sespe and Vaqueros For- mations. These beds may be as old as late Eocene. A locality yielding mammal-bone fragments (VI) near Bolero Lookout, found by Chester Stock of the California Institute of Technology, was recollected and material submitted to G. Edward Lewis of the U. S. Geological Survey. Only three fragments, two upper molar fragments and one incomplete first phalanx, are questionably identifiable. Of these fragmentary speci- mens Lewis (written commun., 1955) states: "all three, although inconclusive, lead me to believe that they rep- resent one of the early giraffe-like line of camelids. I have compared them with W. D. Matthew's type of Paratylopus primaevus at the American Museum in New York, and believe that they represent a closely related species of this genus. The stratigraphic position is most probably upper Oligocene, but possibly lower Miocene. A Sespe equivalent is indicated." Marine invertebrate megafossils collected from the undifferentiated Sespe and Vaqueros Formations are cited in the megafossil lists. Echinoid species com- monly include Kewia? fairbanksi santanensis; molluscan species include Rapana - vaquerosensis - im- perialis, '"Terebra'' santana, and Anadara (Larkinia) santana. In the map area, these species are restricted to the unit and indicate a provincial early Miocene age. REGIONAL IMPORTANCE OF UPPER CONTACT Despite the near conformity of the undifferentiated Sespe and Vaqueros Formations and the Topanga Forma- tion in and near the Santa Ana Mountains, the bound- ary between them marks a time of deformation and erosion in other parts of the Los Angeles basin. Before GEOLOGY OF THE SANTA ANA MOUNTAINS deposition of the Topanga Formation, a new regional landscape was initiated in southern California, and de- formation and erosion in some areas outside the Santa Ana Mountains were increased. Soon therafter, the older sediments were either eroded away or deeply buried. The younger clastic sediments were derived from different types of rocks, in part coming from new sources. The impact of these changes was minimal in the Santa Ana Mountains; as a result, the Paleogene and early Miocene depositional record is more com- pletely preserved there and in the San Joaquin Hills than in other areas south of the Transverse Ranges. MIOCENE SERIES MIDDLE MIOCENE TOPANGA FORMATION The Topanga Formation was first defined by Kew (1923, p. 416-417) for a predominantly sandstone se- quence that crops out in Topanga Canyon in the Santa Monica Mountains and that contains the Turritella ocoyana fauna of provincial middle Miocene age. Kew (1923) recognized the presence of the Topanga Forma- tion in the Puente Hills, Santa Ana Mountains, and San Joaquin Hills. English (1926) mapped the Topanga Formation in the Puente Hills and the northern part of the Santa Ana Mountains. English (1926, p. 24-25) considered the Topanga Formation to be the predomin- antly sandstone sequence that rests disconformably on the Sespe and Vaqueros Formations and is overlain by both the El Modeno Volcanics and the Puente Forma- tion. This report follows the usage of English. North of Santiago Creek, the Topanga Formation is exposed in a continuous band along the south side of Burruel Ridge eastward to Gypsum Canyon. An isolated exposure is present north of the Santa Ana River near the northeast corner of the map area. Southwest of Santiago Creek, the formation crops out discontinu- ously from the vicinity of El Modeno southeastward along the crest of Loma Ridge to the southeast corner of the map area, where it continues into the area map- ped by Vedder and others (1957). The Topanga Forma- tion is known to be present in the subsurface section throughout the lowland area north of Orange, although only a few deep wells have drilled completely through it. Wells southeast of Orange pass directly from rocks younger than the Topanga Formation into the undif- ferentiated Sespe and Vaqueros Formations; the con- tact is an erosional unconformity (Yerkes and others, 1965, fig. 9). In the lowland area south and east of Santa Ana only two wells, the Red Star Oil Co. well, Ward Associates No. 1, and the Hoyt S. Gale well, Ir- vine No. 1, drilled into the Topanga Formation. These occurrences probably represent a northward extension of the 1,800-m-thick section in the northwestern part D37 of the San Joaquin Hills (Vedder and others, 1957; Vedder, 1975). STRATIGRAPHY AND LITHOLOGY BASAL CONGLOMERATE The base of the Topanga Formation is generally fairly well exposed and easily recognized throughout the map area. The undifferentiated Sespe and Vaqueros Forma- tions, which everywhere underlie the Topanga Forma- tion, consist of friable, easily eroded varicolored sandstone and conglomerate of marine and nonmarine origin. The basal part of the Topanga Formation con- sists of tan to gray conglomerate and sandy conglom- erate that ranges in thickness from 2 to more than 9 m. In contrast to the underlying weaker units, it is well cemented and resistant to erosion. Throughout the area, marine mollusks, including large pectinids and oysters, are common in this basal conglomerate; bones of marine mammals occur locally. This basal conglom- erate is prominently exposed in the area north of San- tiago Creek where the undifferentiated Sespe and Va- queros consists almost entirely of nonmarine red beds. The contact is less evident south of Santiago Creek, where the base is less conglomeratic, and the upper part of the underlying sequence contains fossil beds. There is no evidence of an angular unconformity at the base of the Topanga Formation. In some areas the con- tact surface is slightly irregular and has a relief of sev- eral centimeters; in some places the basal conglomer- ate contains clasts of sandstone that seem to have been derived from the undifferentiated Sespe and Vaqueros. SANDSTONE AND CONGLOMERATE SANDSTONE Above the basal conglomerate the Topanga Forma- tion consists chiefly of resistant beds of light-tan to gray, medium- to coarse-grained, poorly sorted feldspathic sandstone that commonly contain crinkly flakes of greenish-black biotite and minor amounts of muscovite. Individual beds range in thickness from 0.3 to 3 m. The less-resistant zones between the resistant beds are composed of finer grained poorly bedded sandstone and silty sandstone. Marine mollusks are generally common in these strata, and some dip slopes are strewn with shark teeth and fragments of whale bone. Between the heads of Weir Canyon and Gypsum Can- yon, where the Topanga Formation is thickest, the lower and middle parts contain beds a meter or so thick of soft greenish-gray and reddish-brown sandstone and silty sandstone similar to that in the underlying undif- ferentiated Sespe and Vaqueros Formations (fig. 18). This rock type was not seen elsewhere. In this area many conglomeratic strata in the upper part of the formation contain cobbles and boulders of distinctive tourmaline-bearing crystalline rock. A similar rock is D38 exposed in the basement complex near Sierra Peak in the map area and in the area southeast of Corona out- side the map area, suggesting an eastern source for at least part of the sediments. Two or more thin beds of white vitric tuff 1.5 to 3 m thick are interbedded in sandstone east of El Modeno. These tuffs, one about 45 m below the top of the To- panga Formation and another about 100 m above the base, have been described by Yerkes (1957, p. 316-317). Fish scales and molds of mollusks are pre- sent in the tuff, indicating deposition in water. To- gether with some fragmental volcanic rocks penetrated only in the Hoyt S. Gale well, Irvine No. 1, in the southwest corner of the area, these tuffs indicate the earliest Tertiary volcanic activity in the Santa Ana Mountains. In the eastern part of the El Modeno area just south of Irvine Park Drive, a bed of creamy white organic siltstone a meter or so thick is the uppermost unit in the Topanga Formation. This siltstone has not been recognized elsewhere. The southwesternmost exposures of the Topanga Formation are at Red Hill, east of Tustin. This hill, sur- rounded by Quaternary deposits, consists of thoroughly GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA fractured sandstone that appears to be clayey, altered, and somewhat tuffaceous. Fairbanks (1893, p. 118) re- ported the presence of mercury in thin veins of barite that cut the sandstone. When visited in 1951, no evi- dence of mercury or barite could be found. Fairbanks (1893, p. 118) believed that the emplacement of the mercury was associated with the volcanic rocks of mid- dle Miocene age (El Modeno Volcanics) that crop out a short distance to the north. The thickest section of the Topanga Formation within the map area is at the east end of Burruel Ridge, be- tween the heads of Gypsum and Weir Canyons. A sec- tion 689 m thick was measured there of fossiliferous white to tan to reddish-brown sandstone, pebbly to coarsely conglomeratic in many beds, especially near the top. Quartz is the principal mineral; feldspar is abundant and biotite fairly common. On the south side of Burruel Ridge, 3 km southwest, the formation is 120 m thick. Farther south, a measured section in the west corner of Irvine Block 69, southwest of Irvine Lake, is 61 m thick, probably in part because of postdeposi- tional erosion before deposition of upper Miocene strata. This section is composed of interbedded sandstone and siltstone that contains abundant fossils. FIGURE 18.- Basal beds of the Topanga Formation. The beds are massive sandstone and less resistant variegated silty sandstone. View north from road near head of Gypsum Canyon at junction with road down Weir Canyon. Vertical dimension of the Topanga shown about 20 m. GEOLOGY OF THE SANTA ANA MOUNTAINS UPPER CONTACT The contact between the Topanga Formation and the overlying units is everywhere well defined. In areas where the formation is overlain by the El Modeno Vol- canics there is no measurable angular discordance be- tween the two formations. The volcanic rocks, however, probably rest on different parts of the Topanga se- quence in different places, and the contact represents a surface of erosion. Where the Topanga Formation is overlain by the Puente Formation, the abrupt change from sandstone of the Topanga to siltstone of the Puente represents an unconformity, below which different amounts of Topanga have been eroded. The measured discordance between the Topanga and Puente Formations ranges from near zero to 30° (in the Scully Hill area just north of the map boundary). In one area southwest of Irvine Lake, the entire Topanga Formation was eroded before the deposition of siltstone of the Puente. SUBSURFACE DISTRIBUTION In the subsurface section north and west of Burruel Ridge, the Topanga Formation is overlain by either the El Modeno Volcanics or the Puente Formation. Coarse-grained strata of the upper member of the Fer- nando Formation unconformably overlie the Topanga, Formation (and older units) in an area east of Orange (structure sections E-L and L-Q, pls. 2,3). Northwest of Orange and outside the map area, rocks correlated with the Topanga Formation have been penetrated in deep wells drilled along the Coyote Hills and the subparallel "Anaheim nose" to the south, where they occur be:- neath an unconformity at the base of the Puente For- mation and are interbedded in some places with extru- sive volcanic rocks (Yerkes, 1972, pl. 1). Complete subsurface sections of the Topanga Forma- tion have been penetrated in the map area by only a few wells north and southwest of Burruel Ridge. Be- cause the Topanga Formation is sparsely cored, its lithologic character must be surmised from electric-log characteristics and a few samples. An alternating se- quence of gray, medium- to coarse-grained sandstone interbedded with gray siltstone and sandy siltstone predominates in the wells. Conglomerate beds occur sporadically throughout the section and are increas- ingly abundant to the north and east. Dark-colored siltsone and hard mudstone are important constituents in the wells west and northwest of the map area. Al- though adequate control is sparse, the Topanga, pene- trated by wells, seems to be similar to that in the out- crop sections. AGE AND CORRELATION Fossil mollusks are locally abundant in the Topanga Formation and occur throughout the formation. Collec- D39 tions from outcrops and the McKee Oil Co. well, Kokx Comm. No. 8-1 (F160), have been studied, and the species are included in the section "List of Megafos:- sils." Common species include Turritella ocoyana, T. cf. T. ocoyana topangensis, T. temblorensis, Leptopecten an- dersoni, Chione temblorensis, Crassostrea cf. titan subti- tan, and Vertipecten nevadanus. The molluscan faunas are typical of provincial middle Miocene assemblages throughout southern California. Foraminifers are not abundant in the Topanga For- mation of the map area. Three outcrop collections were taken from sandy siltstone near the base of the forma- tion east of Cerro Villa Heights and in the El Modeno area. A core sample (locality m182) from about 410 m above the base of the Topanga Formation in the McKee Oil Co. well, Kokx Comm. No. 8-1, also contains a fairly rich foraminiferal fauna. These faunas were de- scribed by Smith (1960, p. 466 and table 3), who listed 11 species that have been questionably assigned to Kleinpell's (1938) Relizian Stage. The Topanga Formation of the Santa Ana Mountains does not contain as thick or varied a lithologic se- quence as is present on the San Joaquin Hills to the south, where it is divided into three named members (Vedder and others, 1957), or in the Santa Monica Mountains to the northwest where it was first defined by Kew (1932, p. 416-417). The dominant rock in all these areas is sandstone, and the molluscan and foraminiferal faunas are so similar that correlation be- tween the areas is well established. EL MODENO VOLCANICS The name El Modeno Volcanics was proposed by Schoellhamer and others (1954) for a sequence of ex- trusive igneous rocks and minor interbedded sedimen- tary rocks exposed locally in the Santa Ana Mountains; they rest on a surface eroded into the Topanga Forma- tion of provincial middle Miocene age and are uncon- formably overlain by the Puente Formation of provin- cial late Miocene age and locally by even younger strata. The El Modeno Volcanics is divisible into three parts in the type area 2 km east of El Modeno. They are, in ascending order, basalt flows; palagonite tuff and tuff-breccia; and andesite flows and flow breccia. All the parts are probably present in the complexly faulted area between the Peters Canyon Reservoir and Irvine Park, but it was not practicable to differentiate them on the geologic map. The El Modeno is present locally in the subsurface west of the outcrop area. The following summary is based on a detailed study made by Yerkes (1957). The main outcrop area of the El Modeno Volcanics is in the low hills immediately east of the town of El Mo- deno. Isolated remnants crop out along the south side of D 40 Burruel Ridge and southeast of Cerro Villa Heights. In the subsurface, the El Modeno is present in wells along the west margin of the area from the Union Oil Co. well, Chapman No. 29, on the north to the Trustees De- velopment Association well, No. 1, on the south (struc- ture sections A-H and M-F, pl. 2). The fragmental vol- canic rocks present in the Hoyt S. Gale well, Irvine No. 1, in the southwest corner of the area are believed to be an older volcanic unit interbedded with the Topanga Formation. These rocks in the Gale well probably rep- resent a northern extension of similar rocks exposed in the northern part of the San Joaquin Hills and in the subsurface section to the northwest of them (Vedder and others, 1957). The maximum outcrop thickness of the El Modeno is about 230 m. Three wells for which reliable data are available penetrated the complete volcanic sequence. These include the Union Oil Co. well, Chapman No. 29, just northwest of the map area, where about 100 m is present. Other wells in the area between Olive and Orange drilled into the volcanic rocks but did not penetrate through the sequence. None of the deep wells drilled into the Topanga Formation near the Olive oil field, in the Kraemer oil field, or along the north side of Burruel Ridge found volcanic rocks, although such rocks are widely distributed farther west in the Los Angeles basin (Eaton, 1958; Yerkes, 1972). Submarine accumulation for at least a part of the basalt flows of the El Modeno Volcanics is indicated by: pillows with siltstone seams and by overlying fossilifer- ous marine siltstone. The bedded palagonitic material presumably was deposited in water deep enough to ef- fect fairly uniform sorting over a relatively large area;; winnowing by winds probably facilitated the sorting to» some extent. The angularity of the fragments shows:; they are not reworked subaerial deposits. Large blocks. having distinct cooling cracks occur locally in the ande- site flows and flow breccia, each block lying in a matrix: of vesicular lava or palagonitic tuff. This is strong evi- dence of deposition of hot avalanche deposits charac- teristic of some volcanic explosions. Thus, the El Mo- deno Volcanics probably includes both submarine and subaerial deposits. No evidence was found to indicate a source for the deposits, although the uniformity of the sequence and distribution of individual lithologic units throughout the series indicates a source or sources that extruded large quantities of material over a wide area. ASSOCIATED IGNEOUS ROCKS A few andesite and basalt dikes too small to be shown on the geologic map intrude the El Modeno Volcanics, the Topanga Formation, and the Santiago Formation. Steep or vertical vesicular and porphyritic andesite dikes intrude the Topanga Formation and the palago- nite tuff, andesite flows, and flow breccia of the El GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA Modeno Volcanics in the eastern part of sec. 23, T. 4 S., R. 9 W. The dikes are generally less than 3 m thick and commonly less than 1.5 m thick; all are composed of porphyritic augite andesite identical with that of the andesite flows and flow breccia. The similarities in composition and field relations suggest that the dikes are nearly equivalent in age with the andesite flows and flow breccia. Dense black basalt dikes cut the Topanga Formation in the area south of Panorama Heights, in the east part of sec. 23, T. 4 S., R. 9 W., and the Santiago Formation near the mouth of Weir Canyon. These dikes are pet- rographically similar and are rather finely porphyritic, having phenocrysts up to 0.7 mm in maximum diame- ter. These dikes are younger than the Topanga Forma- tion; they may be contemporaneous with or younger than the El Modeno Volcanics. Altered basalt is present in the Standard Oil Co. well, Zaiser-Brelje Community No. 1, between 1,325 and 1,355 m depth. This rock is believed to be intrusive along a fault that separated the Topanga Formation from the undifferentiated Sespe and Vaqueros Forma- tions, and a second small dike or sill is completely en- closed by the undifferentiated Sespe and Vaqueros. AGE AND CORRELATION Fossils in sedimentary rocks of the El Modeno Vol- canics and in the underlying and overlying formations permit dating of the El Modeno. The siltstone at the top of the basalt flows in the El Modeno area contains fish scales of probable middle Miocene or early late Miocene age (W. T. Rothwell, in Yerkes, 1957, p. 317). The claystone bed that overlies the basalt flows in the southeastern part of Burruel Ridge contains foraminif- ers (locality m183) that are assigned to the upper part of Kleinpell's (1938) Luisian Stage (Smith, 1960, p. 466, table 3). The underlying Topanga Formation con- tains a large molluscan fauna of provincial middle Miocene age and poor foraminiferal faunas questiona- bly assigned to Kleinpell's (1938) Relizian Stage (Smith, 1960, p. 466, table 3). The La Vida Member of the Puente Formation locally rests apparently conform- ably on the andesite flows and flow breccia of the El Modeno and contains foraminifers diagnostic of the lower part of Kleinpell's Mohnian Stage (Smith, 1960). The El Modeno Volcanics thus appears to be provincial middle Miocene in age. Eaton (1958) placed the entire El Modeno in the Luisian Stage (late middle Miocene) on the basis of regional stratigraphic relations. Large volumes of andesitic and basaltic rocks were extruded throughout much of the Los Angeles basin during middle Miocene time. Lava flows and pyroclas- tic rocks are the dominant rock types, but dikes and sills of similar composition are common in some areas. Outcrop areas of volcanic rocks that correlate in part GEOLOGY OF THE SANTA ANA MOUNTAINS with the El Modeno Volcanics include the Glendora- Pomona area (Shelton, 1955), the Santa Monica Moun- tains (Hoots, 1931; Durrell, 1954), the Palos Verdes Hills (Woodring and others, 1946), and the San Joa- quin Hills (Vedder and others, 1957; Vedder, 1975). Volcanic rocks similar to those found in these outcrops extend deeper into the Los Angeles basin and are pres- ent beneath the Inglewood and Dominguez oil fields and on the north flank of the Long Beach oil field; they are also present in the subsurface in the eastern part of the Los Angeles basin, west of the outcrop area of the El Modeno Volcanics. The inferred subsurface extent of upper middle Miocene volcanic rocks is delineated by Yerkes and others (1965, fig.9). MIDDLE AND UPPER MIOCENE MONTEREY SHALE The name Monterey Formation or Monterey Shale has been used in the Coast Ranges of California for a lithologically distinct sequence of diatomaceous and siliceous shale and siltstone of Miocene age, first de- scribed by Blake (1856, p. 328-331) near the town of Monterey. The usage of the name Monterey has a long and complex history that has been reviewed by Wood- ring and others (1940, p. 122-123). The stratigraphy, lithology, and origin of the siliceous rocks in the Mon- terey Formation throughout California have been dis- cussed in detail by Bramlette (1946). Siliceous, diatomaceous, and organic shale and siltstone of provincial middle and late Miocene age crop out sparingly and occur discontinuously along the seaward side of Los Angeles basin from the Palos Ver- des Hills southeast to the vicinity of San Clemente. These rocks have been called the Monterey Shale in the Palos Verdes Hills (Woodring and others 1946, p. 13-40), and this usage has been extended southeast- ward along the coast to include rocks of similar lithol- ogy in the San Joaquin Hills-San Juan Capistrano area (Vedder and others, 1957; Vedder, 1975). To the north in the Santa Ana Mountains and the Puente Hills, part of the upper Miocene Puente Formation is similar lithologically to the Monterey, but it also contains thick and widespread members composed almost entirely of coarse clastic material. The finer grained members of the Puente Formation are also more clastic than their counterparts in the Monterey. Two depositional envi- ronments, now represented by dissimilar lithologic facies, justify the division of these middle and upper Miocene strata in the map area into two formations, the Monterey Shale and the Puente Formation. The rocks here mapped as Monterey Shale represent the northernmost extension of the Monterey facies of the San Joaquin Hills-San Juan Capistrano area. To the south in the Aliso and Oso Creeks area (see. 17, T. 6 S., R. 7 W.) the lower part of the Puente Formation D41 grades laterally southwestward into the Monterey Shale, and the contact is arbitrarily placed at the Cris- tianitos fault and in the alluviated valley of Oso Creek (Vedder and others, 1957). Coarser clastic rocks like those of the Puente occur above the Topanga Forma- tion in the subsurface section northwest of the San Joaquin Hills (Vedder, 1975). Outcrops of the Monterey Shale are restricted to the extreme south edge of the map area in a small up- faulted block between Lambert Reservoir and Agua Chinon Wash. Its westward extension in the subsurface is terminated by the north-trending fault in Bee Can- yon (structure section T-X, pl. 3). Exposures of the Monterey Shale are limited, and the gently rolling hills developed on it are covered by a thin layer of gray to black clayey soil that supports a sparse growth of low brush, grass, and wild mustard on the steeper slopes and that merges in the lower areas adjacent to the major stream courses with thicker alluvial deposits. STRATIGRAPHY AND LITHOLOGY The base of the Monterey Shale is not exposed in the map area. Directly to the south, between Agua Chinon Wash and Serrano Creek, it rests on the Topanga For- mation (Vedder and others, 1957). Presumably this contact is an unconformity, but its exact nature has not been determined because of poor exposures. Farther south in the San Juan Capistrano-San Joaquin Hills area, the Monterey Shale is locally uncomformable on and intertongues with the San Onofre Breccia and suc- cessively overlaps the Topanga, Vaqueros, and Sespe Formations. The Monterey Shale in the map area consists of a poorly exposed sequence of interbedded siltstone and sandstone. The siltstone is white, gray and pale choco- late brown, soft, punky, and generally thinly lami- nated. It contains small flakes of golden-brown mica and locally diatom fragments; foraminifers and fish remains are abundant. The interbedded feldspathic sandstone is light tan, fine to coarse grained, locally graded, and ranges in thickness from thin laminae to beds about 1 m thick. Sandstone and conglomerate of the Pliocene Niguel Formation probably unconformably overlie the Mon- terey Shale in the area between Lambert Reservoir and Agua Chinon Wash, although the contact between the two is not exposed. In the San Juan Capistrano-San Joaquin Hills area to the south, the Monterey Shale is unconformably overlain by the Oso Member of the Capistrano Formation and the Niguel Formation (Ved- der and others, 1957). Judging by the stratigraphy a short distance to the south (Vedder, 1975), the Monterey Shale in the map area is at least 75 m thick. D42. AGE AND CORRELATION Foraminifers were collected from two localities in the Monterey Shale on the east side of the Lambert Reser- voir spillway. The faunas, from localities m184 and m185, included in the section "List of Microfos- sils, 'have been identified by Smith (1960, p. 470, table 4) and questionably assigned to Kleinpell's (1938) Luisian Stage. These and other foraminiferal faunas have been discussed in detail by Smith (1960) and Ingle (1972), who concluded that the Monterey Shale in the San Juan Capistrano-San Joaquin Hills area is provincial middle and late Miocene in age (Lui- sian and lower Mohnian Stages). Where there is lateral gradation of the Monterey Shale into the lower part of the Puente Formation, the strata are not known to be older than late Miocene. As the Monterey Shale in areas to the south includes strata of early middle Miocene age, deposition of the fine-grained organic and siliceous sediments started earlier there and did not begin farther north until late Miocene time. UPPER MIOCENE PUENTE FORMATION The Puente Formation was named by Eldridge and Arnold (1907), p. 103) for exposures in the Puente Hills. They included in it all Miocene siltstone and sandstone in the area between the Santa Ana River and the vicinity of Cahuenga Pass in the eastern part of the Santa Monica Mountains. They divided it into three un- its: the lower Puente shale, the Puente sandstone, and the upper Puente shale. English (1926) used the name Puente Formation for most of the rocks exposed in the Puente Hills north of the Whittier fault and for the rocks of late Miocene age exposed along the north slope of Burruel Ridge south of the Santa Ana River. He divided the Puente Forma- tion into three main units: a lower shale, a middle sandstone, and an upper member that included a suc- cession of alternating shale, sandstone, and conglom- erate. Daviess and Woodford (1949) divided the Puente Formation in the northwestern Puente Hills into four members: a lower siltstone member; a sandstone member; an upper siltstone member; and the Syca- more Canyon Member, which consists of conglomerate and interbedded sandstone and siltstone. Locally the Sycamore Canyon Member grades laterally into the upper siltstone member. Richmond (1952) mapped the Puente Formation in the western part of the Burruel Ridge area and mod- ified English's (1926) usage to make it consistent with that proposed by Daviess and Woodford (1949). Later detailed mapping by the U. S. Geological Sur- GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA vey in the Puente Hills and the Santa Ana Mountains emphasized the need for formal member names for all four main units of the Puente Formation, and these were proposed by Schoellhamer and others (1954) in a preliminary report on the Santa Ana Mountains. In as- cending order these are the La Vida Member, the Soquel Member, the Yorba Member, and the Sycamore Canyon Member. This usage, which has been followed by Durham and Yerkes (1964) and Yerkes (1972) in the Puente Hills to the north and northwest, is con- tinued in this report. In areas on and near Burruel Ridge where the lenslike Soquel Member is locally absent, it is impracticable to differentiate the La Vida and Yorba Members, and these units are shown on the geologic map as undif- ferentiated La Vida and Yorba Members. LA VIDA MEMBER The La Vida Member of the Puente Formation is present along the south slopes of Burruel Ridge and in small isolated patches in the hills south and east of El Modeno. Extensive, discontinuous exposures are found along the higher parts of Loma Ridge from the Peters Canyon Reservoir southeast to the head of Limestone Canyon. Along the southern edge of the map area, the westernmost exposure is between Bee Canyon and Round Canyon. East of Agua Chinon Wash, it forms a continuous belt that extends to the southeast corner of the map area, where it grades laterally into the Mon- terey Shale near the head of Oso Creek (Vedder and others, 1957). Exposures of the La Vida Member are generally poor except for those found on steep slopes, in the bottoms of flushed-out gullies, and in excavations. Smooth, rounded hills underlain by the member are covered with a thick mantle of gray to black clayey organic soil that contains occasional angular fragments and blocks of limy white siltstone. The soil supports a lush growth of grass and wild mustard during rainy seasons. Brush and cactus are rare on the La Vida but grow profusely on sandstone of the overlying Soquel Member and the underlying Topanga Formation. In areas of poor expo- sures this change in vegetation is useful fsr defining contacts. The exposed thickness of the La Vida Member is vari- able; no detailed sections have been measured. In the southeastern part of Burruel Ridge, structure section G-J (pl. 2) suggests a thickness of about 230 m, a maximum for this area. South of Irvine Lake, structure section R-S (pl. 3) indicates a thickness of about 600 m, although this section may be complicated by unde- tected faults, which could not be traced in the La Vida. Structure section A-K (pl. 2), only 1 km to the east, in- dicates a thickness of only 60 m. In the southeastern GEOLOGY OF THE SANTA ANA MOUNTAINS corner of the map area, a sketch section in the first canyon east of structure section T-X (pl. 3) indicates a thickness of about 105 m, probably representative for this area. STRATIGRAPHY AND LITHOLOGY Basal contact and associated rocks A regional unconformity separates the La Vida Member of the Puente Formation from underlying for- mations. On the south side of Burruel Ridge, the La Vida rests on bevelled strata of the Topanga Formation and on basalt that is probably in the oldest part of the El Modeno Volcanics. East of El Modeno, the La Vida rests on the andesite flows and flow breccia, which is the youngest part of the El Modeno Volcanics. South of Irvine Lake and west of Limestone Canyon, the La Vida rests on fault-separated blocks of the undifferentiated Sespe and Vaqueros Formations; different stratigraphic horizons are exposed beneath the unconformity in each block, indicating that the fault displacements occurred before the La Vida formed. Southeast from Irvine Block 117 to the southeast corner of the map area, the To- panga Formation is present beneath the unconformity, with the exception of a short strip between Bee and Round Canyons, where the La Vida rests on the undif- ferentiated Sespe and Vaqueros (fig. 19). The lithologic contrast between the La Vida Member and the underlying units is always sharp. On Burruel Ridge the base of the La Vida is marked by a thin and discontinuous breccia bed composed of blocks and fragments of limy siltstone and other rocks in a matrix of coarse-grained, poorly sorted sandstone. Elsewhere siltstone of the La Vida Member rests directly on older formations and contains little or no interbedded sandstone. On Loma Ridge near the head of Little Joa- quin Valley, sandstone lenses near the base are indi- cated on the geologic map, as are other stratigraphi- cally higher sandstone, conglomerate, and breccia beds. On Loma Ridge the basal unit consists of about 10 m of bone-white, coarse-grained gritty feldspathic sandstone that contains many gray to black subangular to subrounded clasts of siltstone and sandstone similar to rocks in the Bedford Canyon Formation; other rock types are present in less abundance. A thin discontinu- ous bed of light-yellow to tan sandy tuff or volcanic sandstone is locally present at the base of the La Vida Member in the El Modeno area and between Peters Canyon Reservoir and Irvine Lake. A similar tuff is in- terbedded in the basal part of the La Vida Member above the easternmost outcrops of the El Modeno Vol- canics on Burruel Ridge. This tuffaceous unit has been described in detail by Yerkes (1957, p. 322-323). Most of the material in the tuff is believed to be derived from the El Modeno Volcanics. The presence of diffe- rent rock fragments and detrital quartz suggests re- D43 working and lateral gradation into less tuffaceous siltstone and sandstone. Siltstone and sandstone Siltstone is the dominant rock type in the La Vida Member. Minor amounts of fine- to coarse-grained feldspathic sandstone are interbedded. Fresh exposures of the siltstone are dark gray to black: as weathering progresses, the color gradually changes to chocolate brown, pinkish gray, and ultimately almost to white. The dark color of unweathered rock is probably caused by finely disseminated organic material. Fish bones and scales, abundant foraminifers, and cream-colored phosphatic nodules as much as 1 cm in diameter are present locally. Bedding in the siltstone varies from massive and indistinct to well laminated. Most of the siltstone is soft and easily weathered; in some areas it is hard and brittle, and beds 1 m or so thick protrude from the surrounding rock. These harder units appear to be more siliceous and in many places consist of por- cellaneous siltstone or shale. The sandstones are rep- etitiously interbedded in the siltstone and range in thickness from less than a centimeter to a meter or more. They are feldspathic, contain minor amounts of biotite, range from fine- to coarse-grained, and are gray when fresh but weather to a light tan or buff. Len- ticular beds of hard calcareous siltstone that pinch and swell along bedding planes and concretionary zones up to 1.5 m thick make up a minor but conspicuous part of the La Vida. Freshly broken surfaces of the siltstone are gray to brownish-yellow , and exposed surfaces are creamy white. Weathered surfaces are commonly stud- ded with recrystallized tests of foraminifers. Chips and blocks of this hard white siltstone are common in the soil derived from the siltstone beds. Throughout the map area the upper part of the La Vida Member contains more interbedded sandstone than the lower part; the contact with sandstone of the overlying Soquel Member is in most places gradational. On southeastern Burruel Ridge near Weir Canyon, the Soquel transgresses the uppermost La Vida. On Loma Ridge the Soquel cuts more deeply; between the heads of Rattlesnake and Limestone Canyons, it rests on the undifferentiated Sespe and Vaqueros Formations for a distance of about 300m. On the south side of Burruel Ridge a breccia bed about 25 m thick is present within the La Vida Member. It is composed of angular blocks of limy siltstone as much as 1.5 m in maximum dimension enclosed in a matrix of coarse-grained, calcareous sandstone. This intraformational unit rests unconformably on the bevel- led siltstone of the La Vida, progressively truncating older beds of the La Vida toward the east. Coarse- grained gritty feldspathic sandstone and conglomerate D44 occur in the La Vida in the area between Peters Canyon reservoir and Irvine Lake. Presumably these lenses of coarse clastic material, enclosed in a predominantly silty section, originated either from local tectonic activ- ity or penecontemporaneous erosion and deposition and represent local unconformities within the member. Several thin beds of white vitric tuff are present in the La Vida Member in the southern part of the area east of Agua Chinon Wash. These tuff beds, only a meter or so thick, resist weathering poorly and are ex- posed only in road cuts. They are fine grained, soft, massive, structureless, and vitroclastic. Most samples contain some glass shards and pipes; other samples are composed entirely of glass fragments. The glass is clear, fresh, and isotropic and has an index of refrac- GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA tion between 1.4987+0.0003 and 1.5021+0.0003. Three thin sections contain plagioclase (about Ans:), and a fourth sample is composed entirely of glass fragments. Tuff of similar appearance is present in both the La Vida Member and the Monterey Shale in the San Juan Capistrano area to the south. SUBSURFACE DISTRIBUTION The La Vida Member has been differentiated in the subsurface only in those areas where it is overlain by the sandstone of the Soquel Member. It is recognizable everyw*kere in the subsurface north of Burruel Ridge; its southwestern limit within the map area is marked by the line of pinchout (fig. 20) of the Soquel Member, mat > >5 an é “A FicurE 19.- Unconformity between the overlying La Vida Member of the Puente Formation and the undifferentiated Sespe and Vaqueros Formations. South-facing cliff in south quarter corner of Irvine Block 80, south of Irvine Lake. The La Vida Member dips more steeply (north or left) than the undifferentiated Sespe and Vaqueros. View east. 117°52:30" 39° 117° 45" 52' U] 30" Richfield Oil Field | woe Kraemer ,/ ~- \ \ Oil Field 31 R.10W. W ate,. Olive y. % d Oil Field\ Crest of anticline showing direction of plunge, dotted where concealed Trough of syncline showing direction of plunge, dotted where concealed Concealed fault U, upthrown side; D, downthrown side thickness -_ . Oil field 0 d 1000 3000 2000 METERS FIGURE 20.- Schematic map of the northern part of the Orange quadrangle showing relations between fold axes and lines of zero and maximum thickness of sandstone in the Soquel, Yorba and Sycamore Canyon Members of the Puente Formation. SNIVLNNOW VNV V.LNVS HHL 40 ADOTOWHD SFU D46 which trends northwest from the western part of Bur- ruel Ridge to the northwestern corner of the map area (structure sections B-N, A-C, and E-L, pl. 2). In the subsurface section north of Burruel Ridge, the La Vida Member of the Puente Formation rests uncon- formably on both the El Modeno Volcanics and the To- panga Formation. The same relations are exposed along the south side of the ridge. The El Modeno Volcanics is present beneath the La Vida Member in the Union Oil Co. well, Chapman No. 29, and the Texas Oil Co. well, Bennet No. 1, the only wells north of the Santa Ana River to penetrate volcanic rocks similar to the El Mod- eno. Other wells pass directly from the La Vida Member into sandstone and siltstone of the Topanga Formation, and the El Modeno is absent probably be:- cause of erosion. The base of the La Vida Member in subsurface is placed at the base of a dominantly siltstone sequence, a contact easily recognized on electric logs. The few core samples available indicate that the member consists of hard, dark-gray to black siltstone and silty shale. Lo- cally phosphatic nodules, fish scales, and small pyrite crystals are present. Bedding varies from paper-thin laminations containing crushed foraminifers on freshly broken surfaces to massive beds a meter or so thick. The bedding commonly is accentuated by laminae and beds of fine- coarse-grained gray feldspathic sandstone. The interbedded sandstone, which can reach a thickness of 3 m or more, is scattered throughout the member but is most numerous in its upper part. The contact between the La Vida Member and the overlying Soquel Member is placed at the base of a massive sandstone bed, or the lowest of a series where present. Where the massive sandstone of the overlying Soquel Member is missing, the La Vida and Yorba Members cannot be differentiated (except by means of detailed micropaleontology). The thickness of the La Vida Member varies only slightly throughout its subsurface extent. About 340 m of section is present in the Union Oil Co. well, Chap- man No. 29, in the vicinity of the Richfield oil field, and about the same thickness of beds is present in the Shell Oil Co. well, Travis No. 1, 8 km to the east (struc- ture section A-H, pl. 2). About 150 m is present in the Texas Oil Co. well, Carrillo Ranch (NCT-1) No. 1, 2 km farther east. Thicknesses range from 120 to 160 m along the north side of Burruel Ridge, and about 100 m of the La Vida is present in the A. A. Carrey well, Bixby-Nohl No. 1, near the southwestern limit of the northern area in which it is differentiated. AGE AND CORRELATION Megafossils were collected from one locality (F168) south of Irvine Lake in a thin sandstone and conglom- erate bed near the base of the La Vida Member. The GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA only identifiable species is Leptopecten cf. L. discus (Conrad), which is of middle(?) and late Miocene pro- vincial age in California. Foraminifers collected from widely distributed localities in the member have been identified by Smith (1960, p. 468-470, tables 3 and 4) and are cited in the "List of Microfossils." These assemblages belong to the lower part of Kleinpell's (1938) Mohnian Stage. Although foraminifers are locally abundant in well cores of the La Vida Member, no systematic attempt was made to collect and study them. No evidence was found to indicate that the age of the subsurface section differs from that of the outcrop section, and it is provi- sionally assigned to the lower part of Kleinpell's Moh- nian Stage. SOQUEL MEMBER The Soquel Member of the Puente Formation is ex- posed on the south side of Burruel Ridge from the vic- inity of Cerro Villa Heights eastward to Weir Canyon. It was not recognized northeast or west of this outcrop area, where the finer grained, probably in part con- temporaneous rocks are assigned to the undifferen- tiated La Vida and Yorba Members. Patches of the Soquel are present along the crest of Loma Ridge be- tween Peters Canyon reservoir and the head of Lime: stone Canyon, and a separate continuous belt is ex- posed on the south boundary of the map area. The rocky ridges and brushy or tree-covered slopes under- lain by the Soquel are everywhere in sharp contrast to the grassy slopes of the underlying La Vida and the overlying Yorba Members. STRATIGRAPHY AND LITHOLOGY In the Burruel Ridge area the contact between the Soquel Member and the underlying La Vida Member is gradational, and the base of the Soquel is placed at the base of the dominantly sandstone section. At its south- easternmost exposure on Burruel Ridge near Weir Canyon, the base of the member appears to transgress eastward onto successively older strata of the La Vida Member in a way suggesting a local expression of a re- gional unconformity. Southwest of Santiago Creek the map relations indi- cate that the base of the Soquel Member is an uncon- formity. At the west end of Loma Ridge the Soquel rests directly on a tuff at or near the base of the La Vida Member. Between the head of Rattlesnake and Limestone Canyons the Soquel member rests directly on strata of the undifferentiated Sespe and Vaqueros Formations for a distance of about 300 m. Throughout the map area, medium- to coarse- grained feldspathic sandstone containing biotite is characteristic of the Soquel Member. Interbedded thin gray siltstone, conglomeratic sandstone, conglomerate, GEOLOGY OF THE SANTA ANA MOUNTAINS and breccia are local minor variants. At the west end of Burruel Ridge the member consists of interbedded fine- to coarse-grained feldspathic sandstone and minor amounts of gray siltstone. Weathered outcrops are brownish yellow to tan, and fresh exposures are light gray. In this area bedding is well developed in the sandstone and ranges from thin laminae to beds as much as 3 m thick. The member is increasingly coarser grained eastward and is coarsest at the head of Walnut Canyon, where it also has its maximum outcrop thick- ness. There it consists of coarse-grained to gritty sandstone, conglomeratic sandstone, and lenticular conglomerate beds that locally contain blocks of cal- careous siltstone derived from either the La Vida Member or the Monterey Shale. Fine-grained sandstone, sandy siltstone, and siltstone are locally in- terbedded with these coarser clastic units. At its north- easternmost outcrop the Soquel Member consists of coarse micaceous sandstone and grit but lacks con- glomerate, suggesting that grain size decreases slightly northeastward. In the Loma Ridge area the Soquel Member is com- posed chiefly of massive, coarse-grained to gritty. poorly sorted feldspathic sandstone; weathered out- crops range from white to brownish yellow. Thin beds of medium- to fine-grained well-laminated micaceous sandstone and lenticular sandy conglomerate beds con- tain blocks as much as 1 m in maximum dimension of white, calcareous, foraminiferal siltstone, bored by pholads before erosion and redeposition. Along the south side of Loma Ridge east of Bee Can- yon the lithology of the Soquel Member is more varied, and the section is thicker than elsewhere south of San- tiago Creek. The Soquel there consists of a sequence of interbedded sandstone, siltstone, and resistant con- glomerate beds that extend for considerable distances along the strike. These beds contain a few clasts of glaucophane schist and other metamorphic rocks simi- lar to those common in the San Onofre Breccia farther south. Their rarity in the Puente Formation suggests that they may have been derived from the local erosion of the San Onofre and transported northward during a second cycle. A section of the Soquel measured on the ridge east of Agua Chinon Wash (Irvine Blocks 176 and 177) is about 470 m of sandstone, conglomerate, and siltstone between the underlying La Vida Member of the Puente Formation and the overlying Oso Member of the Capis- trano Formation. The Soquel here is in alternating suc- cessions of tan to white sandstone and conglomerate in units 40 to 60 m thick, and chocolate-brown to gray siltstone in units 15 to 75 m thick; marine fish scales are present in the lowest siltstone. Boulders of granitic and metamorphic rocks are up to 45 ecm in diameter. D47 The contact of the Soquel Member with the overlying Yorba Member is believed to be gradational in the Bur- ruel Ridge area. Outcrops are poor, and neither unit contains marker beds sufficiently well exposed near the contact to establish the exact relationship. The top of the Soquel Member is marked by a change from sandstone and some interbedded siltstone to the dom- inantly siltstone sequence of the Yorba Member. The mapping south of Walnut Canyon suggests a southward transgression of the Yorba Member onto the Soquel Member, but lateral gradation is equally or more prob- able. On the south side of Loma Ridge the Soquel Member and the overlying Oso Member of the Capistrano For- mation are apparently conformable. In the area east of Agua Chinon Wash the top of the Soquel Member is placed at the top of the highest chocolate-brown siltstone. Between Bee Canyon and Round Canyon this siltstone is absent, and the top of the member is arbi- trarily placed at the top of the highest evident con- glomerate. The overlying white sandstone of the Oso Member is indistinguishable from that in the upper part of the Soquel Member, and the presence of well- defined conglomerate beds in the Soquel is its only dis- tinctive feature in this part of the area. On Burruel Ridge the Soquel Member is a large sandstone lens of variable thickness that grades west- ward into siltstone in the Cerro Villa Heights area (fig. 20). At the northeastern limit of the Puente Formation near the Santa Ana River, no sandstone is present be- tween the base of the Puente Formation and the base of its Sycamore Canyon Member, indicating that the Soquel Member also grades northeastward into siltstone. North of Cerro Villa Heights the geologic map suggests a thickness of about 150 m for the Soquel Member. It thickens irregularly eastward to the vicinity of Walnut Canyon, where a section about 490 m thick is exposed (structure section G-J, pl. 2). The Aeco Cor- poration well, Nohl-Bixby No. 1, drilled in Walnut Ca- nyon, spudded in the upper part of the Soquel Member and penetrated its base at 485 m depth, verifying the outcrop thickness of about 490 m. Along the crest of Loma Ridge, where the upper part of the Soquel Member has been removed by erosion, its maximum thickness is about 150 m. East of Agua Chinon Wash the measured section is about 470 m thick. SUBSURFACE DISTRIBUTION The Soquel Member is easily recognized in the sub- surface section north of Burruel Ridge. Its southwest ern limit is marked by the pinchout line (fig. 20) that trends northwest from the westernmost outcrop of Soquel sandstone on Burruel Ridge toward the north- D48 west corner of the map area (structure sections B-N, A-C, and E-L, pl. 2). In the southeastern part of the map area the subsurface extent of the member is not known. It is not present in any of the wells drilled west of the mouth of Bee Canyon. Throughout its subsurface extent the base of the Soquel Member is a well-marked lithologic discon- tinuity that is as easily recognized on electric logs as it is in the outcrop. The basal part of the member consists of medium- to coarse-grained gray sandstone and minor amounts of interbedded siltstone. Above its basal part the Soquel Member consists of gray, fine- to coarse-grained sandstone and pebbly sandstone that is generally poorly sorted and feldspathic and contains variable amounts of greenish-black to black biotite. Bedding in the sandstone ranges from thin laminae of fine-grained sandstone to massive sandstone beds many meters thick, Gray to almost black siltstone and sandy siltstone is interbedded in most places and ranges in thickness from discrete beds 6 m thick or more to thin laminae. The contact between the Soquel Member and the overlying Yorba Member is gradational. In the Richfield oil field, northwest of the map area, the low- est producing sandstone is called the Kraemer zone (Gardiner, 1943, p. 357); the top of this zone is corre- lated with the top of the Soquel Member. The thickness of the Soquel Member varies greatly throughout its subsurface extent in the map area. The thickest section is in the Union Oil Co. well, Chapman No. 29, where about 890 m of the Soquel is present (fig. 20). Eastward along the north side of the Santa Ana River the member thins gradually to about 350 m in the Shell Oil Co. well, Travis No. 1, and about 170 m in the Texas Co. well, Carrillo Ranch (NCT-1) No. 1 (structure section A-H, pl. 2). It probably pinches out a short distance southeast of this well, as shown in struc- ture section H-O (pl. 3). Numerous wells have pene- trated the Soquel Member along the north slope of Burruel Ridge, and its thickness there is demonstrably quite variable. About 290 m of the Soquel was pene- trated in the Santa Ana Canyon Oil Co. well, Crowthers No. 1, about 490 m in the Rubicon Co. well, Wilcox No. 1, about 400 m in the G. D. Murdock well, Howell No. 1, and about 685 m in the Richfield Oil Corporation well, Peralta Hills No. 1 (structure section B-N, pl. 2). The member thins rapidly to the southwest and west from the Peralta Hills well. About 190 m is present in the Olive-Ventura Oil Corporation well, Bixby No. 1, and 80 m in the A. A. Carrey well, Bixby-Nohl No. 1. South of the Richfield oil field the Soquel thins from about $90 m in the Union Oil Co. well, Chapman No. \ GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA 29 to about 580 m in the Texas Co. well, Bennet No. 1 (structure section A-C, pl. 2), and to about 110 m in the Universal Consolidated Oil Co. well, Wiley No. 1. This southward thinning takes place over a distance of 2.8 km at a rate of about 280 m per kilometer. The Soquel is not present in the Olive oil field area farther to the south. These data indicate that the Soquel Member is an elongate predominantly sandstone body of lenticular cross section that has a line of maximum thickness (fig. 20) that trends northwestward; its thickness increases progressively from the outcrop area in Walnut Canyon to the vicinity of the Richfield Oil Corporation well, Peralta Hills No. 1, and thence to the Union Oil Co. well, Chapman No. 29. Directly north and west of the Chapman well, the Soquel Member has not been penetrated by drilling, but 3 km northwest, in the east end of the East Coyote oil field, it is more than 745 m thick. The elongate lens is marked by abrupt thinning southwestward toward the line of pinchout and by moderate thinning in a northeasterly direction, a trend that continues farther north and east, in and beyond the Prado Dam quadrangle (Durham and Yerkes, 1964). There its lowest part is a conglomerate with boulders as much as 3 m in diameter. AGE AND CORRELATION No specifically identifiable fossils were found in the Soquel Member, and its age is based indirectly on foraminiferal faunas that were collected from the un- derlying La Vida and the overlying Yorba Members of the Puente Formation. The foraminiferal faunas of the La Vida are assigned to the lower part of Kleinpell's (1938) Mohnian Stage (Smith, 1960). On Burruel Ridge a single locality, m204 (Smith, 1960, loc. m17), in the overlying Yorba Member, yielded foraminifers that have been assigned to the upper part of Kleinpell's Mohnian Stage. Thus a provincial late Miocene age is inferred for the Soquel Member. Along Loma Ridge, fragments of unidentified large oysters and pectinids are locally present in the coarse- grained sandstone of the Soquel Member. Near the head of Limestone Canyon, calcareous blocks in con- glomerate near the base of the Soquel contain foraminifers assigned to the upper part of Kleinpell's Mohnian Stage and suggest that the base of the member may be slightly younger there than elsewhere. Poorly preserved and crushed foraminifers are sparsely present in the interbedded siltstone units of the Soquel Member in the subsurface. In the Richfield oil field area, Wissler (1943) placed the Kraemer zone at the top of the Soquel Member in the upper part of Kleinpell's Mohnian Stage. GEOLOGY OF THE SANTA ANA MOUNTAINS YORBA MEMBER The Yorba Member of the Puente Formation is ex- posed in the Burruel Ridge area. A small fault sliver of the Yorba is also present in the extreme northeastern corner of the map area and is the southern continua- tion of extensive exposures of the member in the Puente Hills (Durham and Yerkes, 1964). STRATIGRAPHY AND LITHOLOGY The contact between the Yorba Member and the un- derlying Soquel Member is believed to be gradational, although it is nowhere well exposed. In the eastern part of Burruel Ridge the lower part of the Yorba Member consists of gray to pinkish-brown indistinctly bedded to well-laminated siltstone containing sandstone interbeds as much as 2 m thick. The amount of sandstone de- creases upward, and the siltstone increases in hardness and platiness, White to yellowish-brown limy concere- tions and concretionary beds a meter or so thick are common in this part of the sequence. In sections 10 and 15, T. 4 S., R. 9 W., at the western end of Burruel Ridge, the lower part of the member consists of friable, well-laminated, white to pinkish diatomite 90 to 120 m thick (Richmond, 1952, p. 8). This diatomite unit could not be traced eastward from this area, although sparse beds of white diatomaceous siltstone and shale are present locally in various parts of the section. The upper part of the Yorba Member consists of gray to pinkish-brown sandy siltstone. In many outcrops this siltstone is completely structureless; it weathers into ir- regular angular fragments. Beds of well-laminated gray to chocolate-brown siltstone, diatomaceous siltstone, and thin sandstone are locally interbedded in this pinkish-brown sandy siltstone. The upper contact is marked by a fairly abrupt lithologic change to coarse- grained gritty sandstone of the overlying Sycamore Canyon Member. This contact is poorly exposed and is believed to be conformable and gradational. Estimates of the thickness of the Yorba Member are approximate because the dip varies over short dis- tances, and small-scale folding distorts the bedding. A sketch section near the west line of section 11, T. 4 S., R. 9 W., where the Yorba Member is unconformably overlain by the lower member of the Fernando Forma- tion, indicates a thickness of approximately 340 m. Structure section G-J (pl. 2). a short distance east of Walnut Canyon, indicates an outcrop thickness of about 150 m, which suggests abrupt changes in thick- ness, a feature typical of all members of the Puente Formation. SUBSURFACE DISTRIBUTION The Yorba Member is present in the subsurface sec- tion north of Burruel Ridge and is differentiated west- D49 waid to the pinchout line of the Soquel Member (fig. 20). ' A thick lens composed almost entirely of sandstone is locally present in the subsurface section of the member. This sandstone is the Chapman sand or zone, a name of local usage among petroleum geologists. The name is derived from the Chapman lease in the Richfield oil field, where the Union Oil Co. obtained production from the zone on March 11, 1919 (Gardiner, 1943, p. 357). Where it is recognized in the subsurface section, the Chapman sand consists of fine- to coarse-grained feldspathic sandstone and minor amounts of interbed- ded gray siltstone. Some siltstone interbeds are as much as 30 m thick and can be easily recognized on electric logs (structure section A-H, pl. 2). Such a siltstone unit within the Chapman sand sequence in the Yorba Linda quadrangle to the north serves as a useful marker to divide the sand into upper and lower parts. Where wells are spaced closely enough for adequate control (structure section A-H, pl. 2), the Chapman sand appears to grade laterally by interfingering into siltstone typical of the Yorba Member. This gradation is generally accompanied by a decrease in thickness, pos- sibly reflecting differences in compactional response to loading. The Chapman sand has been recognized in the sub- surface northeast of a pinchout line that trends north- west from the mouth of Walnut Canyon (structure see- tion B-N, pl. 2) to a pint about 340 m northeast of the General Petroleum Corporation well, Basin-Stern No. 1 (structure section A-H, pl. 2). The Chapman sand also appears in the Standard Oil Company well, Kraemer No. 2-25, and is recognized in other wells to the north (structure section C-C, pl. 2). Its westernmost limit is a line coincident with the southwestern boundary of the Richfield oil field. The Chapman sand was not iden- tified in the Santa Ana Canyon Oil Company well, Crowthers No. 1, because of poor records, or in the outcrop area to the south, where it is either absent or concealed. Farther northeast, strucure section H-O (pl. 2) suggests that the Chapman sand pinches out a short distance southeast of the Texas Co. well, Carrillo Ranch (NCT-1) No. 1. The typical siltstone of the Yorba Member contains abundant interbedded sandstone in its lower part. On electric logs the contact between the Soquel and Yorba Members is selected as the point where sandstone be- comes dominant. This depth can be easily determined in most areas, but in some areas the selection is arbi- trary. The Chapman sand is overlain by a silty shale that ranges in thickness from about 30 to 60 m, commonly D50 called the Chapman shale, by local petroleum geologists, and easily identified by electric logging. The top of this shale marks the conformable contact be- tween the finer grained Yorba Member and the overly- ing coarser grained Sycamore Canyon Member. The Chapman shale is not differentiated southwest of the pinchout of the Chapman sand. In the area west of Burruel Ridge, where the Sycamore Canyon Member is absent (structure sections A-C, E-L, and M-F, pl. 2'), the lower member of the Pliocene Fernando Formation rests uncomformably on the Yorba Member. The subsurface thickness of the Yorba Member is var- iable and depends largely on whether the Chapman sand is absent or present and the degree of lateral gra- dation into the Soquel Member. At the north margin of the map area, the Yorba Member is about 370 m thick in the Union Oil Co. well, Chapman No. 29. Between this well and the east side of the Kraemer oil field (structure section A-H, pl. 2), the thickness of the Yorba increases to a maximum of about 600 m. In the Texas Co. well, Carrillo Ranch (NCT-1) No. 1, a short distance to the east, only about 430 m is present. Along the south side of the Santa Ana River the maximum thickness for the member is about 410 m in the G. D. Murdock well, Howell No. 1. It thins westward to about 200 m in the Richfield Oil Corporation well, Peralta Hills No.1, and thence increases westward to about 400 m in the Universal Consolidated Oil Co. well, C & T No. 1 , where strata assigned to the Yorba Member are lat- eral equivalents of part of the Soquel Member (struc- ture section B-N, pl. 2). The Chapman sand reaches its maximum thickness along a northwest-trending line between the G. D. Murdock well, Howell No. 1, where about 360 m is present, to the Pacific Central Oil Co. well, Boisseranc No. 1, where about 320 m is present (fig. 20). A little more than a kilometer farther southwest, this sand pinches out. The zero-thickness and maximum- thickness lines of the Chapman sand are both north- east of those of the Soquel Member, and the pinchout of the Chapman sand is much more abrupt. It pinches out about 2 km southwest of the maximum line but thins much more gradually eastward and extends at least to Texas Co. well, Carrillo Ranch (NCT-1) No. 1, where it is 55 m thick. The line of maximum thickness of the Chapman sand is about 1.5 km northeast of the maximum of the Soquel. AGE AND CORRELATION Foraminifers and fish scales are present locally in sur- face exposures of the Yorba Member, but in most places, shell material has been removed by leaching and weathering. One diagnostic foraminiferal as- semblage (locality m204), from near the base of the GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Yorba Member northeast of Cerro Villa Heights, con- tains species that are assigned to the upper part of Kleinpell's (1938) Mohnian Stage (Smith, 1960, table 3). The massive, pinkish-brown, sandy siltstone that makes up the bulk of the upper part of the Yorba Member yielded no identifiable foraminifers. Foraminifers and fish scales are commonly present in core samples from the Yorba Member, but no systema- tic attempt was made to collect or study them. Foraminifers from the Richfield oil field area were as- signed by Wissler (1943) to the upper part of the Mohnian Stage and the lower part of Kleinpell's (1938) Delmontian Stage (late Miocene). SYCAMORE CANYON MEMBER The Sycamore Canyon Member of the Puente Forma- tion is exposed on the north slope of Burruel Ridge be- tween the west boundary of section 11, T. 4 S., R. 9 W., and the south side of the Santa Ana River, a dis- tance of 6 km. Exposures are discontinuous north of the river in the vicinity of the Kraemer oil field. STRATIGRAPHY AND LITHOLOGY The contact between the sandstone of the Sycamore Canyon Member and the underlying siltstone of the Yorba Member appears to be conformable, despite a fairly sharp lithologic discontinuity in the Burruel Ridge area. Elsewhere it seems to be gradational through a meter or so of section. Just east of structure section G-J (pl. 2) and about 1 km south of the Rubi- con Oil Co. well, Wilcox No. 1, the Yorba and Syca- more Canyon Members are bounded on the east by a north-trending fault, where the siltstone of the Yorba Member is truncated. The northward extension of this fault is questionable, because lithologically similar sandstone is juxtaposed across it. Richmond (1952, p. 10 and pl. 1) suggested that part of the strata mapped here as the Soquel Member may be the Sycamore Can- yon locally overlapped onto the Soquel. This area may also be complicated by the presence of the Chapman sand, which is well defined in the Yorba sequence in both the Murdock and Rubicon wells to the northeast. The basal part of the Sycamore Canyon Member con- sists mainly of coarse-grained to gritty poorly sorted, feldspathic, micaceous sandstone that ranges in weath- ered samples from gray to yellowish tan. Pebbles are scattered throughout the sandstone, and thin lenses of pebble conglomerate are present locally. Bedding in these units is generally poorly defined. Well-cemented, cliff-forming beds of sandstone as much as 3 m thick are traceable for considerable distances in some areas. A zone of ellipsoidal sandstone concretions as much as 1.5 m in maximum dimension is locally present in the basal part of the member. These concretions are well developed in the area north of Walnut Canyon, where GEOLOGY OF THE SANTA ANA MOUNTAINS they resemble cannonballs protruding from the enclos- ing less resistant sandstone. Concretions are tan and buff on weathered surfaces but light gray where freshly broken. The cementing material is calcium carbonate, and the bonding is so strong that the sand grains com- monly break instead of separating. Poorly developed concretionary horizons are also present locally in other parts of the Sycamore Canyon Member but are not as prominent as those at the base. Sandstone higher in the Sycamore Canyon Member is slightly finer grained and contains abundant interbed- ded siltstone and sandy siltstone. the sandstone is feldspathic, micaceous, rather poorly sorted, and ranges from fine to coarse grained. Bedding is well de- veloped, and the beds range from less than 3 cm to 3 m or more in thickness. The interbedded siltstone varies greatly in appearance. Some is massive and hackly and has the pinkish-brown color typical of that in the upper part of the Yorba Member. Other siltstone beds are gray and greenish gray, well laminated, and contain abundant flakes of greenish-black biotite. Excellent exposures of the upper part of the Syca- more Canyon Member are evident in the roadcut south of the Riverside Freeway, where it cuts through an ex- tensive outcrop about 370 m west of the east edge of the Orange quadrangle. There the member consists of a well-bedded sequence of sandstone and some siltstone, both of which are micaceous; sedimentary structures attributed to turbidity currents or density flows are common. The structures include graded bedding, crossbedding and cross-lamination, slump structures, and load casts. Some angular fragments of siltstone of the Sycamore Canyon are included in the sandstone as clasts together with rare pebbles and cobbles of other rock types. The upper contact of the Sycamore Canyon Member is not exposed in the area northeast of Walnut Canyon. West of Walnut Canyon the contact between the Syca- more Canyon and the overlying lower member of the Fernando Formation appears to be gradational. In this area each of these units is composed of soft, micaceous sandstone of similar appearance, and the contact can- not be accurately located. The exposed thickness of the Sycamore Canyon Member increases from west to east along the north slope of Burruel Ridge. At its western limit it is about 60 m thick (structure section A-K, pl. 2), whereas 5 km to the northeast, about 460 m is present and the upper contact is covered by alluvium of the Santa Ana River. SUBSURFACE DISTRIBUTION The Sycamore Canyon Member of the Puente Forma- tion is widely distributed in the subsurface north of the outcrop area on Burruel Ridge through Peralta Hills D51 and beyond the map boundary in the southern part of Placentia (structure sections A-C, E-L, and M-F, pl. 2). Throughout its subsurface extent the basal part of the Sycamore Canyon Member is represented by sandstone overlying siltstone of the Yorba Member. This contact is sharp and easily recognized on the elec- tric logs of the many wells available in this area. All evidence indicates that it is conformable and probably gradational through a meter or so of section. In the vicinity of the Kraemer oil field and along the north side of Burruel Ridge the basal part of the Syca- more Canyon Member consists of gray, feldspathic, coarse-grained to gritty and locally pebbly sandstone that is poorly sorted and in some areas micaceous. The grain size of the lower sandstone decreases slightly to- ward the west; southwest of the Richfield oil field it is medium to coarse grained, and minor amounts of fine sandstone and sandy siltstone are interbedded. The upper part of the member in the eastern part of the area is a uniform sequence of interbedded fine- to coarse-grained gray feldspathic sandstone that locally contains abundant biotite flakes. Bedding of this sandstone ranges from thin laminae to beds several meters thick. Variable amounts of gray and greenish- gray micaceous siltstone and sandy siltstone are inter- bedded throughout this sandstone but nowhere make up more than 10 or 15 percent of the total. The siltstone occurs as thin laminae in a predominantly sandstone sequence and as discrete beds about a meter thick. The general lithologic character of the Sycamore Canyon Member changes systematically from east to west: The sandstone is increasingly finer grained and siltstone increasingly more abundant as the pinchout line at the southwest is approached. South and west of Atwood, siltstone is locally predominant in the middle part of the Sycamore Canyon and is enclosed by well- developed sandstone beds. Southwest of the Richfield oil field the Sycamore Canyon becomes uniformly silty and contains as much as 50 percent siltstone interbed- ded with the sandstone. The top of the Sycamore Canyon Member is easily recognized in the Richfield oil field area, where the contact is sharp and distinct between sandstone of the Sycamore Canyon and siltstone of the lower member of the Frenando Formation. This contact is believed to be a local unconformity. The member thins to the south (structure section A-C, pl. 2). It is missing in the Olive oil field area and in the outcrops on the western part of Burruel Ridge where the lower Member of the Fer- nando Formation rests on the undifferentiated La Vida and Yorba Members. The lower member of the Fer- nando Formation grades laterally eastward from the Richfield oil field into a dominantly sandstone se- quence similar to that in the Sycamore Canyon. Where D52 the units are coarse grained, the contact cannot be dis- tinguished on electric logs (structure section A-H, pl. 2) and appears gradational. This gradational contact is also present in the outcrop area of the Sycamore Can- yon south of the Santa Ana River and west of Walnut Canyon. The thickness of the Sycamore Canyon Member in the subsurface increases toward the east and reaches an apparent maximum in the subsurface of the Kraemer oil field. The northwesternmost well to pene- trate the member in the map area is Texas Oil Co. well, Kraemer No. 1, in the eastern part of Placentia; about 20 m of Sycamore Canyon is present in this well. The average thickness in the group of wells southwest of the Richfield oil field is about 60 m. From there the thickness increases gradually eastward; about 250 m is present in the Texas Co. well, Vejar No. 1, and thence it increases rapidly to at least 760 m in the Richfield Oil Corp. well, Mohawk-Kraemer No. 1, in the Kraemer oil field area (structure section A-H, pl. 2). East of the Kraemer oil field the member thins to a minimum of about 410 m in the Texas Co. well, Carrillo Ranch (NCT-1) No. 1. South of the Santa Ana River the only well to penetrate a complete section of the Sycamore Canyon Member is the Richfield Oil Corp. well, Peralta Hills No. 1, which spudded some distance below the top of the member. The line of maximum thickness of the Sycamore Canyon Member (fig. 20) trends northwestward from the outcrop area east of the Landers well through the Kraemer oil field; this is a trend similar to that already noted for the Soquel Member and the Chapman sand in the Yorba Member, but it is shifted to the northeast in relation to these older units. AGE AND CORRELATION _ Although diagnostic fossils are sparse, the Sycamore Canyon Member is marine and probably was deposited in moderately deep water. It overlies the Yorba Member, which contains foraminifers that are assigned to the upper part of Kleinpell's (1938) Mohnian Stage, and it underlies the Fernando Formation, which con- tains mollusks of Pliocene age. Here, as in areas to the northwest where the strata include determinable fos- sils, it is considered to be of provincial latest Miocene age. MIOCENE AND PLIOCENE SERIES UPPER MIOCENE AND LOWER PLIOCENE CAPISTRANO FORMATION The Capistrano Formation was named by Woodford (1925, p. 216-217) for exposures in the vicinity of San Juan Capistrano, about 20 km south of the map area. There it is composed mostly of siltstone. It grades northward into massive white coarse-grained to gritty GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA sandstone that has been named the Oso Member of the Capistrano Formation (Vedder and others, 1957; Ved- der, 1972). OSO MEMBER The Oso Member of the Capistrano Formation is ex- posed only in the southernmost part of the map area, from near the mouth of Bee Canyon southeastward across Agua Chinon Wash. Its type area, about 8 km south of the map area, is between Agua Chinon Wash and Oso Creek approximately 4 km east of El Toro (Vedder and others, 1957). Its friable sandstone forms smooth rounded slopes that support a sparse growth of brush and cactus. Most of the outcrop area is covered by sandy soil, although fresh exposures are present in the banks of the larger streams. STRATIGRAPHY AND LITHOLOGY From Borrego Canyon westward to Bee Canyon, the Oso Member either is faulted against or apparently is conformable on the underlying Soquel Member of the Puente Formation. Farther to the southeast the Oso Member is unconformable on the Monterey Shale (Vedder and others, 1957). In the area east of Agua Chinon Wash, the uppermost unit in the Soquel Member is a light-gray to chocolate-brown siltstone; this siltstone is conformably overlain by a friable white coarse-grained to gritty sandstone of the Oso Member. Between Round Canyon and Bee Canyon the poorly ex- posed contact between the Oso and the Soquel may be gradational; the primary difference between the two is that the Soquel contains numerous conglomerate beds, whereas the overlying sandstone of the Oso is only sparsely conglomeratic. Within the map area, the sandstone bed overlying the highest persistent con- glomerate bed of the Soquel has been chosen as the base of the Oso. The sandstones in the two units are in- distinguishable, and the conglomerate at most places is expressed only as float in the soil. From its base upward the Oso Member consists of uniform massive sandstone with no distinctive lithologic or structural features. It is generally and ero- sionally weak, friable, white to pale-yellowish-gray, medium- to coarse-grained to gritty sandstone that is composed of subangular grains of quartz and feldspar. Widely scattered flakes of golden-brown to greenish- black weathered biotite are present as well as sub- rounded fragments of various rock types. Scattered pebbles and cobbles are present. In some outcrops the sandstone is fairly clean and friable, and in others it is slightly cemented and has a matrix of soft, clayey material. The Oso Member from Bee Canyon southeastward to the edge of the map area is overlain unconformably by Quaternary terrace deposits and alluvium. Farther GEOLOGY OF THE SANTA ANA MOUNTAINS south it is overlain conformably be the uppermost part of the Capistrano Formation and the Niguel Formation (Vedder and others, 1957; Vedder 1972, fig. 4). The thickness of the Oso Member is difficult to esti- mate because of poor dip control and the unconformity at its upper boundary. Vedder and others (1957) re- ported a thickness of about 450 m along Serrano Creek 2 km southeast of the map area, but later structure sections (Vedder, 1975) suggest that it is nearer to 300m thick there. Structure section T-X (pl. 3) indi- cates a maximum thickness of about 490 m. AGE AND CORRELATION Fossils other than shark teeth and whale bones are rare in the Oso Member. About 6 km to the south near English Canyon, numerous distorted specimens of a large echinoid were collected; these were identified as Megapetalus lovenioides Clark by Zullo and Durham (1962), and some poorly preserved foraminifers were found near the top of the member. Ellipsoglandulina fragilis Bramlette(?), a foraminifer indicative of Kleinpell's upper Mohnian or Delmontian Stage, has been reported by Vedder and others (1957) from their locality 737b, near the top of the member between Oso and Aliso Creeks. The siltstone of the Capistrano For- mation, into which the Oso Member grades laterally, is more fossiliferous in the area between San Juan Capis- trano and Dana Point, where it contains late Miocene and early Pliocene fossils (White, 1956; Ingle, 1971; Vedder, 1972). The Oso Member probably is the stratigraphic equivalent of the lower part of the Capis- trano Formation (Vedder, 1972, fig. 4) and seems to be no younger than provincial late Miocene. Its correla- tives in the Burruel Ridge area would thus probably in- clude part of the Yorba Member and possibly part of the Sycamore Canyon Member of the Puente Forma- tion. PLIOCENE SERIES The stratigraphic nomenclature of the Pliocene rocks in the Los Angeles basin has a complex history that is discussed in detail by Durham and Yerkes (1964, p. B24, B25) in their report on the geology of eastern Puente Hills. FERNANDO FORMATION Durham and Yerkes (1964) redefined the Fernando Group as a rock-stratigraphic unit of formation rank which encompasses Pliocene strata of the northernmost part of the Santa Ana Mountains and the southernmost part of the eastern Puente Hills (pl. 1). In these areas the formation is divisible into a lower and an upper member. In the Santa Ana Mountains, the Fernando is exposed only at Burruel Ridge; north of the Santa Ana River, it is exposed in the vicinity of Kraemer oil field. D53 LOWER MEMBER The lower member of the Fernando Formation is ex- posed along the north slope of Burruel Ridge from Walnut Canyon westward to near the town of Olive. North of the Santa Ana River and northwest of Kraemer oil field it crops out in several small areas that are continuous with more extensive exposures to the north (Durham and Yerkes, 1959, 1964). The lower member on Burruel Ridge overlies, from west to east, the undifferentiated La Vida and Yorba, the Yorba, and the Sycamore Canyon Members of the Puente Formation. In the same area, the contact between the lower member and the underlying units is uncon- formable - marked by a basal conglomerate - at the west, becoming apparently conformable and grada- tional with the Sycamore Canyon at the east. The lower part of the lower member appears to grade laterally from greenish-gray micaceous sandy siltstone in the western exposures to fine- to coarse-grained micaceous sandstone in the eastern exposures. In the Puente Hills to the north, the basal contact is concealed. There the lower member of the Fernando is mostly massive, coarse-grained, pebbly sandstone. Some interbeds of well-laminated sandy siltstone with biotite are also present. STRATIGRAPHY AND LITHOLOGY The lower part of the lower member of the Fernando Formation, on the north side of Burruel Ridge from Olive eastward for 3 km, consists of conglomerate and breccia (fig. 21), which rests unconformably on the un- differentiated La Vida and Yorba Members and the Yorba Member of the Puente Formation. It locally is at least 6 m thick and consists of subangular to sub- rounded pebbles, cobbles, and boulders with a maximum diameter of about 1.5 m. Richmond (1952, p. 11) reported that the clasts are composed mainly of quartzite, granodiorite, and volcanic rocks (chiefly purple andesite). Blocks of calcareous siltstone bored by pholads also occur. The matrix is yellowish- brown coarse-grained poorly sorted sandstone locally cemented by calcium carbonate. Marine mollusks are present in the cemented parts of the conglomerate. In the steep gully just west of a landslide in the western part of sec. 11, T. 4 S., R. 9 W., the lowest 15 cm of the Fernando is a sandy pebble-cobble conglomerate, over- lain by pale-gray to tan pebbly sandstone, that rests di- rectly on siltstone of the Yorba Member. The contact undulates and is irregular, and there is a discordance in bedding. The variations in attitude, the abrupt change in lithologic character, and the absence of the Sycamore Canyon Member of the Puente Formation, which is present directly east of the landslide, are evi- dence of the unconformity. East of the landslide the D54 basal conglomerate is absent, and coarse sandstone of the lower member appears to rest conformably and gradationally on sandstone of the Sycamore Canyon. In the eastern Puente Hills the basal contact of the lower member is concealed by faulting or by younger units (Durham and Yerkes, 1964, p. B25, B26). The upper part of the lower member is predomin- antly sandy siltstone that includes interbeds of coarse-grained sandstone and conglomerate. The upper contact of the lower member is exposed only on the west end of Burruel Ridge where greenish- gray siltstone is overlain unconformably by conglomer- ate assigned to the upper member of the Fernando Formation. North of the Santa Ana River, within the map area, the basal contact is concealed by faults or by younger GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA units. The best exposures of the lower member of the Fernando Formation are in the excavations made for the Patrick A. Doheny wells 1 km west of the Kraemer oil field. This exposure consists of coarse-grained peb- bly sandstone that is poorly sorted and massive. The sandstone contains interbedded well-laminated greenish-gray sandy clayey siltstone that locally con- tains large amounts of partly leached biotite ranging in color from green to greeish brown to almost black. Graded bedding and cross-lamination are also present. The upper part of the lower member of the Fernando Formation on Burruel Ridge consists chiefly of friable, easily eroded siltstone and fine-grained sandstone, some interbeds of coarse-grained sandstone, and thin lenticular conglomerate beds. The siltstone and fine- grained sandstone are pale greenish gray, and mica is FIGURE 21.- Lower member of the Fernando Formation in roadcut in Riverside Freeway cut. Note conglomerate bed at lower left. Minor fault at right. Vertical dimension of cut is about 10 m. View northwest. GEOLOGY OF THE SANTA ANA MOUNTAINS so abundant that bare surfaces have a micaceous sheen. Beds of friable cleanly sorted medium- to coarse-grained light-gray to tan feldspathic sandstone up to about a meter thick are interbedded within the siltstone. These sandstone beds lend a well-bedded ap- pearance to the massive siltstone. High in the member, in the freeway cut east of Olive, conglomerate lenses are as much as 0.6 m thick. The clasts are moderately well rounded and average from 5 to 10 cm. Pebbles, cobbles, and boulders in the soil of the slopes to the east suggest that conglomerate lenses are also present there. A 0.3-m-thick bed of bone-white tuff in greenish- gray micaceous siltstone and fine-grained sandstone of the lower member is exposed in a Riverside freeway cut 500 m northeast of the intersection with Jefferson Street at the northwest edge of Burruel Ridge. Samples of this tuff were examined by A. O. Woodford, who re- ported that it consists mainly of glass shards with an index of refraction between 1.505 and 1.508. Also pres- ent are clastic grains of quartz, biotite, rare musco- vite, and abundant unidentified clay mineral. The clay mineral and biotite are partially concentrated in frag- ments as long as 4 mm. These fragments suggest some erosion and reworking of the tuffaceous materal. Thin beds of volcanic ash and bentonite have been reported from approximately equivalent rocks in the southwest- ern part of the Los Angeles basin (Wissler, 1943, p. 216-217; Woodring and others, 1946, p. 41) and in sev- eral subsurface localities along the northern shelf of the basin (T. H. McCulloh, 1977, oral commun.). The only exposure of the upper contact of the lower member of the Fernando Formation is at the west end of Burruel Ridge near Olive. There, the greenish- gray siltstone of the lower member is overlain in sharp con- tact by conglomerate of the upper member. The abrupt eastward thinning of the lower member on Burruel Ridge and its proximity to the window of the Puente Formation at its westernmost exposure indicate that the contact is an erosional unconformity. The contact in the area north of the Riverside Freeway is poorly ex- posed and is placed at the base of the lowest conglom:- erate float in the soil. The maximum exposed thickness of the lower member of the Fernando Formation on Burruel Ridge is uncertain. Structure section A-K (pl. 2) suggests a thickness of about 300 m, where the member is uncon- formably overlain by Quaternary terrace deposits. At the west end of Burruel Ridge, where both the lower and upper contacts are unconformities, structure sec- tion M-F (pl. 2) indicates a partial thickness of about 60 m. SUBSURFACE DISTRIBUTION The lithology of the lower part of the lower member of the Fernando Formation and its relations to the un- D55 derlying Puente Formation are variable in the map area. In the Union Oil Co. well, Chapman No. 29, just northwest of the map area the lower contact occurs at a depth of 790 m and is marked by a sharp change from siltstone above to sandstone below. This contact was considered an unconformity by Wissler (1943, p. 218). It can be traced eastward (structure section A-H, pl. 2) only with difficulty, as the Fernando seems to grade downward into the Sycamore Canyon Member of the Puente Formation in a fashion parallel with the change that occurs in the outcrop at the east end of Burruel Ridge (structure section E-L, pl. 2). In wells on the south limb of the syncline north of Burruel Ridge, the Sycamore Canyon Member is absent, and part of the lower member of the Fernando is composed of a vari- able thickness of sandstone and conglomerate that rests directly on the undifferentiated La Vida and Yorba Members. The absence of the Sycamore Canyon Member and the southward coarsening of the lower part of the lower members of the Fernando are evi- dence that the unconformity reported in the Richfield oil field increases in magnitude southward. In the subsurface the major part of the lower member consists of greenish-gray micaceous siltstone, sandy siltstone, fine-grained sandstone, and varying amounts of interbedded gray medium- to coarse- grained sandstone. The upper contact is placed at the top of this siltstone sequence and directly below the conglomerate and sandstone that unconformably over- lie it. This contact is easily recognized on electric logs and is correlated with the upper contact as mapped at the west end of Burruel Ridge. The thickness of the lower member increases south- ward from 220 m in the Union Oil Co. well, Chapman No. 29, just north of the map area to a maximum for the area of 670 m in the Texas Co. well, Hodges No. 1. It thins sharply south of the Olive oil field and is cut out by younger beds (structure sections E-L and M-F, pl. 2). Eastward from the Olive oil field it thins from about 580 m in the Texas Co. well, Olive Unit One No. 2, to about 300 m in the Seaboard Oil Co. well, Christ- ensen No. 1 (structure section B-N, pl. 2). AGE AND CORRELATION Marine mollusks and foraminifers from the lower member of the Fernando Formation are cited in the sections "List of Megafossils" and "List of Microfos- sils." Four of the molluscan localities (F175, F176, and F178 from the basal conglomerate and F177 from higher in the section) were collected and identified by Richmond (1952, p. 11). These specimens are in the collections of Pomona College, Claremont, Calif., and were loaned for reexamination and identification by W. P. Woodring and Ellen J. Moore of the U.S. Geological Survey. D56 Concerning the age and bathymetric depth ranges of these faunas, W. P. Woodring and Ellen J. Moore (1952, written commun.) report: "The age of two of these collections (F174 and F175), consisting of poorly preserved or incomplete specimens, cannot be desig- nated more closely than 'presumably Pliocene'. The few species in the other collections do not afford a basis for differentiating early and late Pliocene. Thyasira gouldii is a moderate-depth species. The other species indicate shallow water." The foraminifers indicate early Pliocene age and a bathyal depth and are similar to early Pliocene foraminiferal faunas from the upper part of the Capis- trano Formation in the San Juan Capistrano area de- scribed by White (1956; 1971) and Ingle (1967; 1971) and the lower part of the Fernando Formation at Upper Newport Bay (Vedder, 1972, 1975; Ingle, 1972), al- though a smaller number of species is represented. Uvigerina peregrina, Epistominella subperuviana, and several species of Cassidulina, which constitute 50 to 75 percent of these faunas, suggest bathyal depth in- terpretations of around 600 m or more. The lower member of the Fernando Formation, pro- vincial early Pliocene in age, is widely distributed in the Los Angeles basin (Yerkes and others, 1965, p. A38-A41, fig. 11) It is referred to informally as the Re- petto Formation in the Palos Verdes Hills, Wilmington and Long Beach oil field, and Repetto Hills areas; it is equivalent to the upper part of the Capistrano Forma- tion in the San Joaquin Hills (White, 1956; Yerkes and others, 1965, pls. 1, 2; Ingle, 1972; Vedder, 1972). UPPER MEMBER The upper member of the Fernando Formation is ex- posed only at the western tip of Burruel Ridge just east of the town of Olive. North of the Santa Ana River, south-dipping strata assigned to the upper member by Durham and Yerkes (1959, 1964) are present along the south margin of the Puente Hills. Exposures of the upper member are poor, for it is poorly consolidated and forms smooth, rounded slopes that support a growth of grass, low brush, and clumps of cactus. The best exposures are at the western tip of Burruel Ridge and in the abandoned gravel pit a short distance to the east. STRATIGRAPHY AND LITHOLOGY The lower part of the upper member of the Fernando Formation consists of interbedded tan and yellowish- brown coarse-grained sandstone and conglomerate in variable proportions. It rests unconformably on siltstone of the lower member; the contact is placed at the base of the lowest mappable conglomerate bed. In a GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA roadcut of the Riverside Freeway this lowest conglom- erate is overlain by a gray micaceous sandy siltstone that is lithologically identical with that present in the lower member. Unsorted and indistinctly bedded con- glomerate and sandstone overlie this sandy siltstone. The conglomerate is composed of pebbles, cobbles, and boulders up to about 30 cm in maximum diameter, but they average 5 to 8 cm and include many as small as sand size. Clasts are composed of many rock types, in- cluding several types of volcanic rock, some of which are similar to the Poway-type clasts in conglomerate of the undifferentiated Sespe and Vaqueros Formations plus schist and gneiss, plutonic rocks, and some light- colored quartzite. These conglomerate beds are lenticu- lar and grade vertically and laterally into the poorly sorted feldspathic sandstone beds that contain a small amount of leached biotite. All gradations are present between sandstone and conglomerate. The highest unit exposed is a soft, easily gullied and very poorly bedded fine-grained sandstone. The upper member is unconformably overlain by flat-lying Quaternary terrace deposits and alluvium. The contacts between these units generally are covered by soil and can be located only approximately. The exposed thickness of the composite upper member is about 30 m, which probably represents only the lower part of the member. SUBSURFACE DISTRIBUTION The upper member of the Fernando Formation under- lies a more extensive area than does the lower member and extends into the southern part of the map area. Along the north side of Burruel Ridge, the upper member is present in the entire area west of State Highway 14. South of Olive the upper member forms a broad strip that extends along the western edge of the map area, except east of the Standard Oil Co. well, Tustin Comm. No. 1, where it is believed to be absent. The upper member cannot be differentiated east of the Amerada Petroleum Corp. well, Irvine No. 63-1 (struc- ture section R-S, pl. 3; see also Yerkes and others, 1965, fig. 14). North of the vicinity of the Union Oil Co. well, Olive Comm. No. 4-1 (structure section A-C, pl. 2), the upper member of the Fernando Formation rests on the lower member. A few core samples from the Texas Co. well, Olive Comm. No. 1, indicate that the upper member is composed of an alternating sequence of friable sandstone, conglomerate, and micaceous siltstone that contains some black carbonaceous material. Fragmen- tary remains of mollusks are present in some of the coarser grained units, and foraminifers are reported from some of the siltstone beds. North of the Texas Co. well the electric logs from all wells that penetrate the GEOLOGY OF THE SANTA ANA MOUNTAINS base of the upper member show a sharp contact be- tween the sandstone and conglomerate of the upper member and the finer grained siltstone of the lower member. This contact is similar to that exposed in the outcrops at the west end of Burruel Ridge. In the area south and east of the Union Oil Co. well, Olive Comm. No. 4-1, and the Tidewater Oil Co. well, Olive-Orange No. 1, where the lower member of the Fernando Formation is not present, the upper member rests directly on older formations. In the area of the Standard Oil Co. well, Taft Comm. No. 1, the upper member rests on the undifferentiated La Vida and Yorba members of the Puente Formation, whereas southeast of Orange it is believed to rest on the bevel- led edges of the El Modeno Volcanics, the Topanga Formation, and the undifferentiated Sespe and Va- queros Formations (structure sections E-L, pl. 2, and L-Q, pl. 3). A few cores were recovered from the upper member in the Shoreline Oil Co. well, Pinkerton No. 1, and are reported to consist mainly of blue clay, silt, and sandstone, containing some molluscan fragments and foraminifers. Conglomerate is also believed to be present, although it was not cored. A sharp contact is reported at 554 m in this well, where red beds of the undifferentiated Sespe and Vaqueros Formations occur below the upper member of the Fernando Formation. In several wells south and east of Santa Ana, friable sandstone, conglomerate, and siltstone of the upper member rest on the undifferentiated La Vida and Yorba Members (Amerada Petroleum Corp. well, Irvine No. 63-1; Red Star Oil Co. well, Ward Associates No. 1; and Hoyt S. Gale well, Irvine No. 1). These wells are so widely separated and the available data so poor that correlation with the upper member in the area north of Orange is questionable. In the southern area the upper member may include marine equivalents of the La Habra Formation of Pleistocene age, which is not known to be present in the Red Star Oil Co. and the Hoyt S. Gale wells. The upper member of the Fernando Formation is be- lieved to rest unconformably on formations older than the lower member throughout the subsurface area; these relations are especially clear south of Olive, where the lower member is absent and older forma- tions are present beneath the unconformity. Electric logs indicate that the upper part of the upper member is finer grained, especially in the area north of Olive where more siltstone is interbedded. The contact with the overlying La Habra Formation is believed to be an unconformity. The La Habra is coarser grained and nonmarine in origin. In the subsurface the upper con- tact of the La Habra cannot be distinguished from rocks of several other formations because of the non- diagnostic characteristic of the rocks as recorded in electric logs. D57 The thickness of the upper member of the Fernando Formation is extremely variable. About 250 m is pres- ent in the Union Oil Co. well, Chapman No. 29, at the north edge of the map area. The member thickens rapidly to the south and is thickest near the Texas Co. well, Ruff No. 1, where about 920 m is present (struc- ture section A-C, pl. 2). Farther south it thins rapidly and is absent in Standard O1 Co. well, Tustin Commun- ity No. 1 (structure section E-L, pl. 2). About 220 m is present in the Shoreline Oil Co. well, Pinkerton No. 1, and about 280 m in the Amerada Petroleum Corp. well, Irvine No. 63-1. In the extreme southwestern part of the area, strata tentatively assigned to the upper member have a minimum thickness of about 610 m in the Red Star Oil Co. well, Ward Associates No. 1, and about 370 m in the Hoyt S. Gale well, Irvine No. 1. AGE AND CORRELATION No fossils of any kind were found in exposures of the upper member of the Fernando Formation in the map area. Foraminifers and poorly preserved mollusks are reported in it outside of the map area, where the species generally indicate marine deposition in shallow water. In the Puente Hills to the north (Durham and Yerkes, 1964, p. B26, B27) large molluscan faunas of late Pliocene age were found at several localities in the upper member. Depths greater than 50 m and as much as 200 m are suggested by molluscan assemblages at Newport Bay in the uppermost part of the Fernando Formation (Vedder, 1972). The upper member of the Fernando Formation, as- signed a provincial late Pliocene age, is widely distri- buted in the Los Angeles basin (Yerkes and other, 1965, p. A41-A44, fig. 14). Vedder (1960, 1972) provi- sionally correlated these strata with the Niguel Forma- tion in the San Juan Capistrano area and the upper part of the Fernando Formation at Newport Bay. NIGUEL FORMATION The Niguel Formation was named by Vedder and others (1957) for exposures on the Niguel land grant in the San Juan Capistrano quadrangle. The type area, about 13 km south of the map area, is immediately west of Galivan Overpass on former U.S. Highway 101 (1949 edition, San Juan Capistrano quadrangle) about 7 km north of San Juan Capistrano. The formation uncon- formably overlies Monterey Shale and the Capistrano Formation and is overlain unconformably in turn by Quaternary stream deposits. It is chiefly poorly con- solidated light-gray to white micaceous feldspathic sandstone interbedded with gray sandy siltstone. Con- glomerate and breccia are locally present near the base. South of the map area, the formation is mostly marine, and molluscan assemblages in the lower part D58 were assigned a provincial late Pliocene age by Vedder (1960, 1972). The upper part of the formation lacks fossils and may be nonmarine. Fossils have not been found in the formation within the map area. Structure section T-X (pl. 3) indicates a thickness of about 150 m. The Niguel Formation is exposed in four small patches along the southern edge of the map area, be- tween the mouth of Round Canyon and Agua Chinon Wash. Its westward extension beneath the alluvium is terminated by the fault that trends south from Bee Canyon and passes just west of the Lambert Reservoir. Smooth, rounded, cobble-strewn hills covered by a growth of low brush and clumps of cactus are typical of the Niguel Formation. Grass rather than brush grows on the black clayey soil developed on the underlying Monterey Shale, and this change in vegetation and soil is used to define the contact between the two units in most places. STRATIGRAPHY AND LITHOLOGY Only the lower part of the Niguel Formation is present in the map area. It consists of coarse-grained poorly sorted yellowish-brown sandstone and interbedded massive conglomerate that locally contains blocks of calcareous siltstone derived from either the Monterey Shale or the Puente Formation. Many of these siltstone blocks have been bored by pholads, which suggests that the siltstone was redeposited in water not deeper than about 35 m (Revelle and Fairbridge, 1957, p. 280). Vedder (1960) stated that molluscan as- semblages from the Niguel outside the map area suggest and inner sublittoral-depth facies (low water to about 100 m). The best exposures of the Niguel Formation in this area are in a gravel pit about 150 m south of the westernmost natural outcrop of the formation. There, the formation consists of a complex sequence of inter- bedded sandstone, conglomeratic sandstone, and con- glomerate. In fresh exposures the sandstone is white to very pale greenish gray, fine to coarse grained, poorly sorted, and feldspathic. Some thin clayey streaks im- part a well-bedded appearance to the sandstone. Slightly darker colored tubes 2 ecm in diameter and 2 to 8 cm long are present in the sandstone. These are usu- ally perpendicular to the bedding, and the sand grains in the tubes are coarser and "cleaner" than the sur- rounding sandstone, which suggests activity by burrow- ing mollusks, crustaceans, or worms. The sandstone and the conglomerate occur as lenses and pods that are indistinctly crossbedded. The conglomerate is light yel- low brown and is composed of completely unsorted clasts that range in size from 2 to about 30 cm in maximum diameter and average from 5 to 10 ecm. The clasts range from subangular to rounded and consist of GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA volcanic rocks in various shades of gray, red, and ma- roon that were probably derived from the undifferen- tiated Sespe and Vaqueros Formations, plus plutonic rocks, quartzite, gneiss, and other metamorphic rocks. Some clasts of very friable greenish-gray clayey sandstone up to 10 cm in diameter are also present. The matrix of the conglomerate is very poorly sorted feldspathic sandstone having angular to subrounded grains. Thin surface coatings of clayey material hold the grains together, and the sandstone and conglomer- ate in the quarry stands as cliffs that are rapidly gul- lied during wet seasons. Fossils other than filled bur- rows have not been found in the Niguel Formation within the map area. QUATERNARY SYSTEM PLEISTOCENE SERIES ILA HABRA FORMATION The name La Habra Conglomerate was used by H. M. Bergen in as unpublished report on the geology of the Bastanchury ranch (in the vicinity of Fullerton and Brea), and the name was first published by Eckis (1934, p. 49-50). Durham and Yerkes (1959), during mapping of the area northwest of the Santa Ana Moun- tains, reexamined the type La Habra and, because of the wide variety of lithologic types, renamed it the La Habra Formation. In the type area between Brea and Carbon Canyons in the La Habra and Yorba Linda quadrangles, it consists of buff conglomerate and con- glomeratic sandstone that contain angular chips and blocks of white siltstone, reddish earthy sandstone, and greenish-gray massive siltstone. The base of the La Habra Formation is a regional unconformity that trans- gresses marine sandstone and conglomerate of early Pleistocene age in the La Habra quadrangle and the upper and lower members of the Fernando Formation in areas to the east along the south flank of the Puente Hills. The base of the La Habra is not exposed in the Santa Ana Mountains. The La Habra is unconformably overlain by Quaternary terrace deposits and alluvium. Durham and Yerkes (1959) mapped the La Habra For- mation eastward as far as the town of Yorba Linda and discussed its presence in the subsurface as far south as the edge of the Yorba Linda quadrangle where it ad- joins the Orange quadrangle. The only exposure of the La Habra Formation in the map area is in the gravel pit on the north edge of the Orange quadrangle about 3 km east of the town of At- wood (fig. 22). It is surely present beneath alluvium in all the wells drilled for oil north of the Santa Ana River and west of the Yorba bridge across the Santa Ana River. South of the river the subsurface correlations are more questionable, and south of the town of Orange the wells are so widely separated and the sub- GEOLOGY OF THE SANTA ANA MOUNTAINS surface information so sparse and inconclusive that the term La Habra Formation is used only tentatively for the post-Pliocene rocks that are known to underlie the alluvium. STRATIGRAPHY AND LITHOLOGY The base of the La Habra Formation is not exposed in the map area. About 2 km north of Yorba Linda, south-dipping massive white conglomeratic sandstone at the base of the La Habra (Durham and Yerkes, 1959) rests unconformably on siltstone and conglomer- ate of the upper member of the Fernando Formation. D59 The base of the La Habra Formation is at 307 m depth in the Union Oil Co. well, Chapman No. 29, at the north edge of the map area (Durham and Yerkes, 1964), where it is underlain by the upper member of the Fernando Formation. In most other wells the con- tact is obscure and questionable. The La Habra rests on the upper member of the Fernando Formation as far south as the Standard Oil Co. well, Zaiser-Brejli Comm. No. 1, but south of there the data are inconclu- sive. At the Standard Oil Co. well, Tustin Comm. No. 1, the La Habra Formation rest unconformably on undif- ferentiated siltstone of the Puente Formation. South of FicurE 22.- Pebbly sandstone of the La Habra Formation, unconformably overlain by older alluvium. View south of wall of gravel pit 1 km west of Yorba Linda Reservoir. Cut is about 12 m high. D60 this well the upper member of the Fernando Formation reappears below the unconformity (structure section E-L, pl. 2). South and east of the Shoreline Oil Co. well, Pinkerton No. 1, rocks that are questionably assigned to the La Habra Formation rest unconformably on older rocks that include the Topanga Formation, the undifferentiated Sespe and Vaqueros Formations, the Williams Formation, and the Holz Shale Member of the Ladd Formation, in addition to the upper member of the Fernando Formation (structure sections L-P, U-V, and U-W, pl. 3). About 6 m of the La Habra Formation is exposed be- neath stream-terrace deposits in the gravel pit at the north edge of the Orange quadrangle. There, the La Habra Formation is a massive, very friable, white con- glomeratic sandstone. Individual grains of the sandstone are completely unsorted angular to sub- rounded quartz and feldspar clasts that are covered by a film of white clayey material. Dark minerals such as mica are almost completely absent. The individual sand grains range from fine- to granule size and local dis- continuous lenses of pebble conglomerate are present. Most of the larger clasts are light-colored plutonic rocks, although a few subanglular fragments of greenish-gray sandy siltstone, similar in lithology to beds in the upper member of the Fernando Formation, are present. No fragments of siltstone were found in this sequence. At places bedding is suggested by con- centrations of pebbles, but these are rather obscure and variable and may be indications of crossbedding. Well data on the lithologic character of the La Habra Formation south of the outcrop area are limited to elec- tric logs, old driller's logs, and a few core samples. These indicate that the La Habra Formation consists of interbedded soft sandstone, conglomerate, and minor amounts of siltstone. Cores from the Texas Co. well, Olive Community No. 1, the Standard Oil Co. well, Tustin No. 1, and the Shoreline Oil Co. well, Pinkerton No. 1, indicate that the La Habra Formation in that area consists of yellow clay, yellow clayey sandstone, gray siltstone, and fri- able conglomerate. The La Habra Formation lacks fossils almost everywhere in the map area and is probably almost en- tirely nonmarine. Beneath the southwestern lowlands, however, at least one marine tongue is present, just a meter or so below its top, in Amerada Petroleum Corp. well, Irvine No. 63-1, at the southwest end of structure section R-S (pl. 3). Other marine tongues may be pres- ent still farther southwest, where the post-Miocene rocks of the subsurface cannot be subdivided on the basis of available data. GEOLOGY OF THE SANTA ANA MOUNTAINS PLEISTOCENE AND HOLOCENE SERIES TERRACE DEPOSITS Within the map area, terrace deposits include fluvial sediments that lie well above active stream courses and the modern floodplain. Some of the terrace deposits are structurally deformed, but most are nearly flat ly- ing. Typically, they are weathered to various shades of reddish and yellowish brown and form steplike features along Santiago Creek and its main tributaries. The ter- race deposits are subdivided into deformed alluvial de- posits and older alluvium. DEFORMED ALLUVIAL DEPOSITS Alluvial deposits that have been conspicuously de- formed occur at two places within the area mapped. One of these is on the south side of Burruel Ridge; the other caps the high part of Loma Ridge. The two widely separated deposits probably are not correlative. On the south side of Burruel Ridge, a deformed allu- vial deposit is similar to older alluvium along Santiago Creek, but its uphill edge, instead of being marked by a terrace riser, is bounded by a north-dipping fault, on which the La Vida Member of the Puente Formation is thrust over the younger unit. Here the deformed allu- vial deposit is unconformable on the underlying To- panga Formation. Just below the base of the deformed deposit, the Topanga Formation dips as much as 60° N., and the contact dips 24° N. and strikes N. 40° W. The deformed alluvial material consists of an unsorted mixture of pebbles, cobbles, and boulders of many lithologic types in a gray and tan earthy clayey sandy matrix similar in appearance to material from weath- ered surfaces of the El Modeno Volcanics. The upper contact of this deposit is a thrust fault, which strikes N. 27° E. and dips 42° N. where best exposed; 2 to 10 cm of siltstone gouge is present along the fault. At the east end of this exposure the thrust fault has been dropped down a short distance by a northwest-trending normal fault. The maximum ex- posed thickness of the deposit is about 15 m. The high- est and oldest deposits assigned to the older alluvium of Santiago Creek bury the western end of the outcrop. The faulted deposit is similar to other terrace deposits in lithology and general appearance; its primary differ- ence is in the amount of deformation. The higher part of Loma Ridge has a relatively flat upper surface, and summit elevations increase south- ward. The elevation is 399 m in the western part of Ir- vine block 68; 6 km southeast, in block 117, the summit elevation is 540 m. In this block, deformed alluvial de- posits of coarse sand and gravel cap Hills 1760 and GEOLOGY OF THE SANTA ANA MOUNTAINS 1775. The perched gravel, which overlies the Puente Formation on these hills, is considered an erosional remnant of once widespread fluvial deposits. These folded deposits lie along the trough of a small north- east-trending syncline. OLDER ALLUVIUM Deposits associated with the modern drainage system are present along both sides of the Santa Ana River and along Santiago Creek and many of its tributaries, including the lower parts of Blind Canyon, Fremont Canyon, Limestone Canyon, Silverado Canyon, and the west fork of Ladd Canyon. They are all of late Pleis- tocene age, although the youngest may be of Holocene age. The older alluvium along Santiago Creek is locally well preserved (fig. 23) and has been subdivided on the basis of its relative altitude above the stream into four numbered units. East of Orange, the deposits of San- tiago Creek merge with the younger alluvium of the coastal plain to the west and south, and an arbitrary contact between the two units is shown on the map. Elsewhere in the map area no systematic division of the older alluvium could be made. Small isolated rem- nants of terrace deposits not now associated with the present drainage are found near the head of the west fork of Hall Canyon, along the crest of Loma Ridge on D61 the boundary between Irvine blocks 117 and 118, and in the area adjacent to the mouth of Round Canyon at the south edge of the map area. These deposits appa- rently have not been deformed. The older alluvium is variable in composition. It gen- erally consists of a mixture of angular to rounded peb- bles, cobbles, and boulders derived from older forma- tions in a matrix of clayey red sand and silt. A local source for much of this material is indicated by the presence at some places of concentrations of calcareous siltstone fragments derived from the Puente Formation plus sandstone and siltstone blocks, as well as gray cal- careous concretions, derived from the Upper Creta- ceous and Tertiary formations. The maximum clast size is about 1 m, and the average size is less than 0.3 m. Some outcrops consist of earthy sandstone, and many individual beds are composed almost entirely of small siltstone fragments. Both the coarse- and fine-grained units locally show poorly developed crossbedding. The color of the older alluvial material is generally yellowish to reddish brown, although gray outcrops are exposed in fresh cuts. In some outcrops the material is weak and crumbly and has been weathered and oxidized in places, whereas in other areas the material is relatively fresh and unweathered. These variations in weathering appear to be random and local rather than related to age or area of deposition. FicurE 23.- Terraces and older alluvium north of junction of Santiago and Silverado Creeks. Qoa 2, 3, 4, older alluvium; Qya, younger al- luvium. View northeast from Santiago Canyon Road 1 km west of intersection with Silverado Canyon Road. D62 The various isolated remains of older alluvium on ter- races range in thickness from less than a meter to 60 m. Fossils have not been found in the older alluvium within the map area, but elsewhere in the Los Angeles basin, equivalent beds have yielded numerous verte- brates of Pleistocene age (Miller, 1971). YOUNGER ALLUVIUM The younger alluvial deposits include material now being actively transported by streams and slightly older deposits of the same general character, upon which the present streams flow. Locally these deposits are incised as much as 6 m by stream action. The southwestern part of the map area is covered by younger alluvium deposited by the two major streams, the Santa Ana River and Santiago Creek. Southeast of Tustin, small southwest-draining washes that head along the crest of Loma Ridge have contributed much material to this alluviated area. The coalescing of these and many other alluvial fans has formed the broad smooth surface which slopes away from the hills toward the Pacific Ocean southwest of the map area. This low- land area, about 80 km long and 25 to 30 km wide and having an area of approximately 2,000 square kilome- ters, is the central, sinking part of the Los Angeles ba- sin. The southwestern margin of the basin is low, and the major streams have cut through it to the sea. For this reason the lowland was called a coastal plain by Mendenhall (1905, p. 11) and locally the Tustin Plain by Poland and Piper (1956). No systematic study of the lithologic character and variation of the younger alluvial deposits was made for this report. With the exception of the through-flowing Santa Ana River, all the alluvium has been locally de- rived. It consists of interbedded and unconsolidated mud, sand, pebbly sand, and gravel. Fresh exposures are various shades of gray, depending upon the color of the local source rocks and the amount of washing by stream action. Younger alluvium along stream courses in the higher parts of the Santa Ana Mountains consists mainly of pebbles, cobbles, and boulders derived from the Bedford Canyon Formation, the Santiago Peak Vol- canics, and material reworked from conglomerate in formations of Tertiary age. Along the south side of Loma Ridge, the younger alluvium contains abundant subangular fragments of white siltstone derived from the La Vida Member of the Puente Formation. The clasts size decreases rapidly downstream; the material distributed on the gently sloping Tustin Plain in the western and southern part of the area consists of clayey sand and silt. These surface sediments have been weathered to form gray sandy loam and dark-gray to black clayey sandy gumbo soils. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA The Santa Ana River transports material derived from the eastern Puente Hills, the northern slope of the Santa Ana Mountains, and areas of alluvium and basement rock to the east and north. The alluviated river valley varies in width from about 1 km where it enters the area from the northeast to about 3 km be- tween the towns of Olive and Atwood, where it merges with the Tustin Plain. Surface exposures of these younger alluvial deposits are medium- to coarse- grained feldspathic sand that contain variable amounts of clay and silt, which, when dry, bind the sand grains together. Core drilling was done in the Santa Ana River channel in order to evaluate possible dam sites, and the results of this work have been published by Post (1928, p. 261-264). One set of coreholes was drilled across the river channel parallel to structure section H-O (pl. 3) and indicated an alternating sequence of sand, gravel, and boulders as large as 25 ecm. Bedrock was reached at depths of 25 m below the surface. Little is known about the subsurface lithologic character of the younger alluvium that covers the older rocks in the southwestern part of the area. All data must be obtained from well records, but most wells drilled for oil penetrate alluvium without coring or sampling, and electric logs are run only after surface casing has been set, generally below the base of the al- luvium. Where ditch samples and electric logs are available they indicate an alternating and lenticular sequence of silt, sand, and gravel. Many water wells drilled in the area penetrate the younger alluvium, and geologic data of varying quality are available from them. Much of this material has been published by Mendenhall (1905), Eckis (1934), Piper (1953), Po- land and Piper (1956), and Singer (1973). These re- ports deal primarily with the water-bearing charac- teristics of the younger rocks, and stratigraphic and lithologic information is generalized. The thickness of the younger alluvium ranges from zero to a known maximum of about 140 m in the Amerada Petroleum Corporation well, Irvine No. 63-1, in Irvine Block 63. The thickness may be much greater in the central part of the Los Angeles basin. STRUCTURE The area covered by the geologic map (pl. 1) is the broad southwestern flank of a very large northwest plunging anticline. It can be divided into two main structural parts: the small area northeast of the Whit- tier and Elsinore faults, which is structurally related to the eastern Puente Hills area (Durham and Yerkes, 1964), and the main mass of the mountains southwest of these faults. The core of the southwest-tilted main block, at its northeastern edge is a narrow, northwest: trending belt of Mesozoic basement rocks. GEOLOGY OF THE SANTA ANA MOUNTAINS The principal local complexity is the faulted westward-plunging anticline that makes up the north- western part of the range. Here, no basement rocks are exposed, but the Upper Cretaceous and Cenozoic rocks dip northwest in the northernmost part of the range and south or southwest in the area southeast of Irvine Park (lower Santiago Creek). The anticlinal axis trends through the lower part of Black Star Canyon, the mouth of Blind Canyon, and thence westward across Santiago Creek in the vicinity of the National Securities Oil Co. well, Irvine 1, until it apparently terminates against the El Modeno fault east of El Modeno. REGIONAL STRUCTURAL PATTERN NORTHEAST OF WHITTIER-ELSINORE FAULT The Whittier-Elsinore fault transects the northeast: ernmost corner of the map area and separates the Upper Jurassic(?) and Lower(?) Cretaceous Santiago Peak Volcanics on the south from Upper Cretaceous and younger sedimentary rocks on the north. The area north of this fault is structurally part of the eastern Puente Hills (Durham and Yerkes, 1964); it is charac- terized by west-trending faults, vertical and overturned strata of similar trend, and at least one tight over- turned fold. The Whittier fault trends approximately S. 80° E. from its intersection with the Santa Ana River to the small north-trending cross fault in Fresno Canyon, which offsets the main fault about 200 m to the south. Southeast of this cross fault, the trend of the main fault varies around S. 55° E. It is commonly called the Elsinore fault, and it makes the northeastern scarp of the Santa Ana Mountains. Nowhere along the Whittier-Elsinore fault zone in the map area could the dip of a fault plane be measured, but poorly exposed gouge zones in the bottoms of several steep gullies suggest that the zone in this area is either vertical or dips steeply to the south or southwest. The Holz Shale Member of the Upper Cretaceous Ladd Formation has not been recognized outside of the Santa Ana Mountains-San Joaquin Hills area. Its pres- ence north of the Whittier fault and in the deep and narrow Chino-Corona trough (Gaede, 1969) with simi- lar lithology, thickness, and fossil assemblage suggests that little strike slip has occurred on this segment of the Whittier-Elsinore-Chino fault complex since middle Cretaceous time, an interpretation also suggested by the inferred distribution of Paleocene strata (Yerkes and others, 1965, fig. 7). The known petrologic, strati- graphic, and structural features of the Upper Creta- ceous and Cenozoic strata in the Santa Ana Mountains, the Puente Hills, and eastern Los Angeles basin seem to be consistent with this conclusion. The lithology and shape of the sandstone lens in the Soquel Member of D63 the upper Miocene Puente Formation, from the con- glomerate at its head near Pomona to the sandstone toe near Anaheim, are especially significant. The only large break in the Soquel is at the Whittier fault, and the displacement here must be almost entirely dip slip. SOUTHWEST OF WHITTIER-ELSINORE FAULT ZONE South and west of the Whittier-Elsinore fault the rocks are complexly faulted and folded and are divided arbitrarily into three parts: the exposed structures, the buried structures south of the El Modeno fault, and the buried structures north of the El Modeno fault. EXPOSED STRUCTURES FAULTS Numerous faults with various trends and displace- ment cut the rocks that crop out south and west of the Whittier-Elsinore fault. In general these faults trend either northwest or northeast, although some faults tend west and north. Many of the north- or northwest- trending faults are longer and have greater apparent vertical separations. Curved and sinuous fault traces are common, and several of these change strike as much as 90° along their length. About 260 separate fault traces are shown on plate 1, but many other small ones have not been mapped. Of the faults mapped, 160 show stratigraphic separations that are down on the west, and 100 show separations that are down on the east. The amount of movement down on the west is of greater overall magnitude. The oldest dated fault in the mapped area is exposed for a thousand meters or so along the crest of the Santa Ana Mountains, in the vicinity of the intersection of Black Star Canyon-Skyline Drive and the Main Divide Motorway. It is younger than the Santiago Peak Vol- canics and older than the Ladd Formation. Near struc- - ture section R-S (pl. 3), the fault dips 20° northeast and is marked by a gouge zone several centimeters wide. Here the Baker Canyon Conglomerate Member of the Ladd Formation is nearly horizontal and lies uncon- formably across the Bedford Canyon Formation, the Santiago Peak Volcanics, and the gently northeast dip- ping thrust( ?) fault separating them. The Irvine Lake dam and spillway on Santiago Creek, south of the mouth of Fremont Canyon, are constructed on fault blocks of Upper Cretaceous and lower Tertiary rocks. The principal faults are shown on structure sec- tion L-Q (pl. 3) just east of its intersection with struc- ture section A-K (pl. 2). The Baker Canyon Conglomer- ate and Holz Shale Members of the Ladd Formation are upfaulted in a north-trending slice that extends from 600 to 2,000 m north from the spillway. The apparent downthrow on the two faults east of Blind Canyon is D64 about 760 m on the western one and about 450 m on the eastern one. Near the mouth of Bee Canyon an uplifted block of the Williams and Silverado Formations is bounded on at least three sides by normal faults. Northwest of Bee Canyon the largest fault strikes about N. 60° W. and separates the undifferentiated Sespe and Vaqueros and Santiago Formations on the north from the Williams Formation on the south. This fault appears to turn southward beneath the alluvium of Bee Canyon and separates the Williams Formation on the west from the Soquel Member of the Puente Formation and the Oso Member of the Capistrano Formation on the east. The fault dips 55° E. in an irrigation ditch 330 m north- east of Tomato Spring. A concealed northeast-trending branch of this fault continues up Bee Canyon beneath the alluvium to separate the Santiago Formation on the northwest from the upper part of the undifferentiated Sespe and Vaqueros Formations on the southeast. A normal fault that strikes about N. 20° E. and dips 55° W. bounds this block of the Santiago on the west. This fault continues north to Limestone Canyon and dis- places the Topanga and Puente Formations on Loma Ridge. Structure section U-W (pl. 3) indicates a stratigraphic separation of about 500 m for this fault near its south end. Where the undifferentiated Sespe and Vaqueros are faulted against the Williams, the stratigraphic separation on the main fault could be as much as 800 m. The displacement on the south- trending part of the main fault in the Lambert Reser- voir area cannot be estimated because of lack of data on the thickness of the Silverado Formation exposed on the east. Data from the Shell Oil Co., Irvine core holes 2 and 5, indicate that a structural high is present in that area, and structure section T-X (pl. 3) suggests a downdrop of about 300 m east of the main fault. The longest continuous fault trace is that of the El Modeno fault. It extends about 19 km from Little Joa- quin Valley at the southeast to the Olive oil field at the northwest. Although concealed beneath Quaternary deposits along much of its length, its continuity is es- tablished by exposures and subsurface information. The El Modeno fault has been recognized in the sub- surface for a distance of about 21 km northwest of the map area (Yerkes and others, 1965 fig. 3). As early as 1924, Ferguson and Willis (1924, p. 578) published a small-scale map of the Los Angleles basin that showed a similar fault continuing southeast along the course of Santiago Creek and a more southerly trending branch that approximates the surface trace of the El Modeno fault in the area south of Santiago Creek. Between Little Joaquin Valley and Santiago Creek, the El Modeno fault is exposed discontinuously, the fault trace is sinuous, and its trend averages about N. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA 15° W. On this segment the surface trace of the fault indicates a westward dip. In the Little Joaquin Valley area structure section R-S (pl. 3) indicates a downthrow on the west of about 300 m; 2 km to the north, structure section L-Q (pl. 3) shows a downthrow to the west of about 400 m. The only exposure of the fault northwest of Santiago Creek is 890 m east of the Texas Co. well, Ragan (NCT-1) No. 1, where the Topanga Formation on the southwest is in contact with the undifferentiated Sespe and Vaqueros Formations on the northeast. A fault con- tact between the Santiago Formation, or possibly the Silverado Formation, and the Williams Formation is be- lieved to be present in Ragan (NCT No. 1 at a depth of about 1,415 m. This contact correlates with the El Modeno fault; the indicated dip is about 70° to the southwest. Structure section M-F (pl. 2), drawn through the McKee Oil Co. well, Kokx Comm. 8-1, indi- cates a downthrow to the south of about 550 m. The stratigraphic sequence in the Kokx well is believed to be normal and to be thinned by unconformities rather than by faulting, which would require a dip steeper than 70° for the El Modeno fault. The youngest strata cut by the fault in this area are referred to the La Habra Formation of late Pleistocene age. The Union Oil Co. well, Olive Comm. 4-1, southwest of the town of Olive drilled through the El Modeno fault at a depth of about 1,270 m; it passed from the El Modeno Volcanics into the undifferentiated Sespe and Vaqueros Formations, and the Topanga Formation is faulted out. Structure section E-L (pl. 2) indicates a stratigraphic separation of about 340 m in this area. The location and throw of the El Modeno fault are not precisely known west-northwest of this well. In the southern foothills of the Santa Ana Mountains, between Little Joaquin Valley and the Peters Canyon reservoir, a horst of the undifferentiated Sespe and Vaqueros and Santiago Formations is bounded on the west by the El Modeno fault and on the east by a nearly parallel fault. The stratigraphic separation is about 460 m on the east side of the horst and 600 m on the west side, as shown by structure section L-Q (pl. 3). Along the southwest slope of Loma Ridge east of the horst, the La Vida Member of the Puente Formation rests unconformably on the undifferentiated Sespe and Vaqueros Formations. In the area between the head of Little Joaquin Valley and the head of Rattlesnake Can- yon to the east, a group of northeast-trending faults cut the undifferentiated Sespe and Vaqueros but can be traced for only short distances into the overlying La Vida Member. In several of the individual fault blocks, the undifferentiated Sespe and Vaqueros cannot be matched across faults, which suggests greater dis- placements in these pre-late Miocene rocks. Some of GEOLOGY OF THE SANTA ANA MOUNTAINS these faults that cut the Puente Formation may have been active before the deposition of the La Vida, for only relatively small post-Puente movement is evident. In the northwestern Santa Ana Mountains, faults commonly show greater displacement in the Cretaceous and lower Tertiary rocks than in the middle Miocene and younger rocks. The evidence suggests repeated movements on old faults. FOLDS The whole Santa Ana Range is a large northwest: trending asymmetric anticline whose northeastern limb is dropped down along the Elsinore fault and whose north-plunging nose is cut off by downfaulting on the Whittier fault zone. The broad and undulating, com- plexly faulted southwest limb makes up most of the mountains. It is divisible structurally into two rather vague folds, the major west-trending anticline with an axis extending west from Black Star Canyon through Irvine Park to the El Modeno fault, and a northwest- trending syncline centered on Loma Ridge between upper Santiago Creek and Peters Canyon reservoir. The northeast limb of the syncline that underlies Loma Ridge has relatively gentle dips and is uncompli- cated by major faults. The southwest limb is steeper and is complicated by local folds and by the structur- ally high fault blocks in Little Joaquin Valley and the Bee Canyon area (structure sections R-S, U-V, U-W, pl. 8) Minor anticlines and synclines are imposed on the main folds of the northwestern Santa Ana Mountains and are widely scattered in the area. The most impor- tant of these is the anticline exposed at the northern edge of the map area, on which the Kraemer oil field is located. The axis of this asymmetrical fold trends about N. 55° E.; dips are less than 45° on the northwest flank and greater than 45° on the southeast flank. Three kilometers east of the Kraemer oil field, two small an- ticlines and two small synclines are partially exposed (structure section H-O, pl. 3). The axis of the north- ernmost anticline trends about N. 45° E. Several small folds are exposed on the western part of Burruel Ridge; they apparently plunge westward be- neath the alluvium of the Santa Ana River. The Richfield Oil Corp. well, Peralta Hills No. 1, was drilled on the surface trace of a westward-plunging anticline offset by a small northwest-trending fault. A small shallow syncline is present directly to the south (struc- ture section A-K, pl. 2). Two opposing dips in strata of the lower member of the Fernando Formation just south of the Riverside Freeway near Peralta Hills mark the eastern limit of a west-plunging anticline that may continue into the Olive oil field. At the west end of Burruel Ridge the A. A. Carrey well, Bixby-Nohl No. 1, was drilled on the surface trace D65 of a small northwest-plunging anticline (structure see- tion M-F, pl. 2). Sharp chevron folds in the lower member of the Fernando Formation on the northwest side of the Riverside Freeway are probably part of this structure but cannot be shown at the scale of the geologic map. A small syncline to the south has a more westerly trend and plunges westward beneath the al- luvium south of the town of Olive (structure section E-L pl. 2). Near the head of Fremont Canyon in the northeast- ern part of the map area a small southwest-plunging anticline exposes the Holz Shale Member of the Ladd Formation at its core (structure section H-O, pl. 3). These minor folds have developed on the north limb of the main west-trending high of the northwestern Santa Ana Mountains. A small southeast-plunging anticline is exposed in the Silverado and Santiago Formations 1 km northwest of Irvine Lake. Its position in relation to the south limb of the northwestern Santa Ana Mountains high is shown on structure section R-S (pl. 3). South of Loma Ridge a well-developed anticline ex- tends from Bee Canyon eastward across Round Can- yon. This fold trends about S. 75° E. A syncline to the south trends about N. 60° W. near Bee Canyon but plunges southward through an isolated outcrop of the La Vida Member of the Puente Formation and termi- nates abruptly against a west-trending normal fault. Two small folds are exposed in the upfaulted block of undifferentiated Willams Formation of the Bee Canyon area. The northernmost of these is an anticline that trends about N. 60° W. near Bee Canyon (structure section U-W, pl. 3). A syncline a short distance to the south has a curved trace but is subparallel to the anti - cline. Both folds terminate against a fault on the east and appear to die out westward. The Texas Co. well, Irvine (NCT-2) No. 1, in Little Joaquin Valley was drilled on a small anticline north- east of the El Modeno fault (structure section R-S, pl. 3). this fold strikes about N. 40° W., and both ends ap- pear to terminate against the fault. SUBSURFACE STRUCTURES SOUTH OF EL MODENO FAULT From the El Modeno fault southward to the vicinity of Orange the general pattern of the subsurface structure is fairly well documented by well records. The well den- sity, however, is not sufficient to reveal small faults and folds. South and southeast of Tustin the wells are so widely separated and the stratigraphic section so variable that only broad structural features are discer-. nible. FAULTS : Only the larger faults exposed along the southwestern margin of the Santa Ana Mountains in the Bee Canyon D66 area are traceable beneath the alluvium. It is believed that the faults that bound this block of Upper Creta- ceous strata must extend southwest for some distance, and the presumed relations are shown on structure see- tion T-X (pl. 3). FOLDS The main subsurface fold south of the El Modeno fault is the Anaheim nose, a broad, gently northwest- plunging anticline, discussed in detail by Yerkes and others (1965, p. A48, A49). This structural feature can be recognized as far west as the vicinity of Buena Park, about 14 km northwest of the map area. Along the crest of the Anaheim nose, relatively undeformed Pliocene sedimentary rocks rest unconformably on middle Miocene and older sedimentary rocks. The upper Miocene Puente Formation laps out against the flanks of the structure and has been recognized on top of the structure only in its northwestern part (see Yerkes and others, 1965, structure section E-F, pl. 4). The gentle northern flank of the Anaheim nose is shown on structure section E-L (pl. 2). The axis of the structure is presumably near the Shoreline Oil Co. well, Pinkerton No. 1, although no subsurface data for precise location are available on the area directly to the south. In this well the upper member of the Fernando Formation rests unconformably on the undifferentiated Sespe and Vaqueros Formations. The older strata dip northward, and successively younger rocks are present beneath the unconformity in the area to the north. Many unconformities are associated with the growth of the Anaheim nose in this area. The oldest one known is at the base of the Puente Formation. This middle Miocene deformation is widespread throughout the Los Angeles basin (Barbat, 1958, p. 39-40; Yerkes and others, 1965, pl. 2). Local unconformities associated with the Anaheim nose include those at the base of the lower member of the Fernando Formation, at the base of the upper member, and at the base of the La Habra Formation, indicating continuing deformation since the middle Miocene. Sparse well data in the area southeast of Tustin suggest that the Anaheim nose may extend toward the structural high of Upper Cretaceous strata in the vicin- ity of Bee Canyon. The Amerada Petroleum Corp. well, Irvine No. 63-1 (structure section R-S, pl. 3), passed directly from the Puente Formation into the Williams Formation at a depth of 1,080 m. The West American Oil Co., well Irvine No. 1, 2.7 km to the northeast, penetrated the top of the Williams Formation at a depth of about 905 m and continued in sparsely fos- siliferous Upper Cretaceous rocks to about 1,720 m, where it penetrated rocks questionably correlated with the Bedford Canyon Formation or the Santiago Peak GEOLOGY OF THE EASTERN LOS ANGELES BASIN, CALIFORNIA Volcanics. No data are available on the age of the rocks above the Williams Formation, but the thick sequence of lower Tertiary rocks exposed 2 km to the northeast suggests that some of these rocks are present in this well. However, erosion of at least part of the lower Ter- tiary sequence in the area to the south is shown by the unconformity at the base of the Puente Formation. Strata of the undifferentiated Sespe and Vaqueros Formations are present southeast of the Amerada well (structure section T-X, pl. 3), and in the Shell Oil Co. well, Irvine Corehole No. 4, they rest unconformably on the Williams Formation. This is the only area in the northwestern Santa Ana Mountains where this uncon- formity has been found. The repeated unconformities indicate the significance of the Anaheim nose, and to- gether with Bee Canyon high, the nose marks an im- portant structural trend. SUBSURFACE STRUCTURES NORTH OF THE EL MODENO FAULT FAULTS No faults of large magnitude are known to be present in the subsurface north of the El Modeno fault. Gar- diner (1943, p. 359) indicated east-northeast-trending faults on the south side of the Richfield oil field, and Saunders (1958, p. 150) showed north- and east- trending faults in the Olive oil field. The anomalously thick section of the lower member of the Fernando Formation in the Texas Co. wells, Dowling No. 1 and No. 2, and Kraemer No. 1, suggests the presence of a west- or north-trending fault in these wells. FOLDS The largest fold in the subsurface north of the El Modeno fault is a west-trending west-plunging syncline that can be recognized from southeast of the Kraemer oil field to the west edge of the map area north of the present channel of the Santa Ana River. North of this syncline the structure rises rapidly into the Kraemer and Richfield anticlines, both the sites of oil fields. On the south flank of the Richfield oil field a small sub- sidiary syncline and anticline trend N. 70-80° E. (structure section A-K, pl. 2). South of the syncline that underlies the Santa Ana River, a west-plunging anticlinal axis passes through the Richfield Oil Corp. well, Hamrick-Olive No. 1 (structure section E-L, pl. 2), and continues westward to the Olive oil field. a smaller, parallel syncline south of the town of Olive plunges westward from the outcrop at the west end of Burruel Ridge. Fold axes in the late Miocene and younger rocks have a westward or slightly southwestward trend in the area north of the El Modeno fault, whereas south of the GEOLOGY OF THE SANTA ANA MOUNTAINS fault the main structural feature, the Anaheim nose, trends northwestward. Uplift of the Anaheim nose began during middle Miocene time, and the distribution of the Puente For- mation sandstone bodies indicates that the growing fold acted as a barrier to the sand that was carried in from the north and east. These sandstone bodies were deposited in a northwest-trending trough or basin the axis of which lies athwart the axis of the Santa Ana River syncline. Northeastward migration of the trough during late Miocene time is indicated by the progres- sive shifting of the maximum thickness lines of younger and younger sand units in that direction. In this area, accentuation of northwest-trending folds ap- parently continued at least to the end of the Miocene. The more westerly trending folds are much younger. SUMMARY AND REGIONAL INTERPRETATIONS The structure of the northern Santa Ana Mountains is dominated by (1) the broad north-plunging anticline that underlies the main mass of the mountains and is truncated at the northeast by the Whittier fault, (2) the northwest-trending anticline that underlies the southwest flank and plunges northwest beneath the Los Angeles basin as the Anaheim nose, and (3) numerous north- to northwest-trending, down-to-the-west normal faults that cut the folds into numerous blocks (Yerkes and others, 1965, figs. 2, 3). The faults commonly show evidence of repeated movement, and the longest one (El Modeno fault) cuts strata of late Pleistocene age. The geologic coherence of the Santa Ana Mountains and adjoining parts of the Peninsular Ranges province - San Joaquin Hills to the south amd southwest, Los Angeles basin to the west, Puente Hills to the north, and Perris Block to the east-has been established (Durham and Yerkes, 1964; Yerkes and other, 1965: Vedder and others, 1957; Vedder, 1975; this report). Thus, interpretations based on geology of the Santa Ana Mountains have regional significance: (1) The unconformity separating the basement and superjacent sedimentary rocks represent major tec- tonic and erosional events sometime between Late Jurassic and Late Cretaceous time (Tithonian(?) to lower Turonian). (2) Exposed Upper Cretaceous and lower Tertiary sedimentary rocks provide a stratigraphic reference section for the sparsely drilled pre-Miocene subsurface sequence beneath the entire eastern Los Angeles basin. (3) Southwestward tilt of the mountain block in Late Cretaceous and early Cenozoic time is recorded by the northeastward transgression of the Paleocene Silverado Formation onto successively older members of the D67 Upper Cretaceous sequence and thence onto basement rocks. data from adjoining parts of the Peninsular Ranges province show that to the north and east of the mapped area Paleocene, Eocene, Oligocene(?) and Miocene strata successively become the oldest sedimentary rocks to rest on the basement surface; that surface is presumed to be an early Cenozoic relic. (4) The early Cenozoic erosion surface persisted for a considerable time in a moist tropical or subtropical climate, as indicated by the Paleocene Claymont Clay Bed and associated strata. (5) Provenance of lower Tertiary conglomerates, in- cluding those of early Miocene age (undifferentiated Sespe and Vaqueros Formations), contrasts with that of later deposits. 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Paleontologists and Mineralogists, Pacific Sec., 88 p. 1972, Biostratigraphy and paleoecology of early Miocene through early Pleistocene benthonic and planktonic Foramini- fera, San Joaquin Hills, Newport Bay, Orange County, Califor- nia, in The proceedings of the Pacific Coast Miocene biostrati- graphic symposium: Soc. Econ. Paleontologists and Mineralogists, Pacific Sec., 47th Ann. Conv., p. 255-283. Jones, D. L., Blake, M. C., and Rangin, Claude, 1976, The four Jurassic belts of northern California and their significance to the geology of southern California borderland, in Howell, D. G., ed., Aspects of the geologic history of the California conti- nental borderland: Am. Assoc. Petroleum Geologists, Pacific Sec., Misc. Pub. 24, p. 343-362. Kennedy, M. P., and Moore, G. W., 1971, Stratigraphic relations of Upper Cretaceous and Eocene formations, San Diego coastal area, California: Am. Assoc. Petroleum Geologists Bull., v. 55, no. 5, p. 709-722. Mallory, V. S., 1959, Lower Tertiary biostratigraphy of the California Coast Ranges: Tusla, Okla., Am. Assoc. Petroleum Geologists, 416 p. Kew, W. S. W., 1923, Geologic formations of a part of southern California and their correlation: Am. Assoc. Petroleum Geologists Bull., v. 7, no. 4, p. 411-420. Kleinpell, R. N., 1938, Miocene stratigraphy of California: Tulsa, Okla., Am. Assoc. Petroleum Geologists, 450 p. Lang, H. R., 1978, Late Cretaceous biostratigraphy of the southeast- ern Los Angeles basin: California Division of Oil and Gas, Spec. Rept. No. TR20, 15 p. Larsen, E. S., 1948, Batholith and associated rocks of Corona, Elsi- nore, and San Luis Rey qudrangles, southern California: Geol. Soc. America Mem. 29, 182 p. Listsyna, N. A., 1957, Corrosion of quartz in Meso-Cenozoic weath- ered mantle in northern Kazakhstan: Akad. Nauk SSSR, v. 114, no. 4, p. 862-865. Matsumoto, Tatsuro, 1959-60, Upper Cretaceous ammonites of California: Kyushu Univ., Mem. Science, v. 8, p. 91-171; Spec. Vol. 1, p. 14172; v. 2, p. 1-204. GEOLOGY OF THE SANTA ANA MOUNTAINS Mendenhall, W. C., 1905, Development of underground waters in the eastern coastal plain region of southern California: U. S. Geol. Survey Water-Supply and Irrigation Paper No. 137, 140 p. Miller, W. E., 1971, Pleistocene vertebrates of the Los Angeles basin (exclusive of Rancho La Brea): Los angeles County Mus. Bull. Sci., no. 10,124 p. Minch J. C., Gastil, Gordon, Fink, William, Robinson, John, and James, A. H., 1976, Geology of the Vizcaino Peninsula, in Howell, D. G., ed., Aspects of the geologic history of the California continental borderland: Am. Assoc. Petroleum Geologists, Pacific Sec., Misc. Pub. 24, p. 136-195. Moran, A. L., 1976, allochthonous carbonate debris in Mesozoic flysch deposits in Santa Ana Mountains, California: Am Assoc Pe- troleum Geologists Bull., v. 60, no. 11, p. 2038-2043. Nordstrom, C. E., 1070, Lusardi Formation: A post-batholithic Cre- taceous conglomerate north of San Diego, California: Geol. Soc. America Bull., v. 81, no. 2, p. 601-605. Packard, E. L., 1916, Faunal studies in the Cretaceous of the Santa Ana Mountains of southern California: California Univ. Pubs., Dept. Geology Bull., v. 9, p. 137-159. Peterson, G. L., 1971, Stratigraphy of the Poway area, southwestern California: San Diego Soc. Nat. History, v. 16, p. 225-236. Piper, A. M., 1953, Native and contaminated ground waters in the Long Beach-Santa Ana area, California: U. S. Geol. Survey Water-Supply Paper 1136, 320 p. Poland, J. F., and Piper, A. M., 1956, Ground water geology of the coastal zone, Long Beach-Santa Ana area, California: U. S. Geol. Survey Water-Supply Paper 1109, 162 p. Poore, R. Z., 1976, Microfossil correlations of California lower Ter- tiary sections: A comparison : U. S. Geol. Survey Prof. Paper 743-F,8 p. Popenoe, W. P., 1937, Upper Cretaceous Mollusca from southern California: Jour. Paleontology, v. 11, p. 379-402. ___ 1941, The Trabuco and Baker conglomerates in the Santa Ana Mountains: Jour. Geology, v. 49, no. 7, p. 738-752. ___ 1942, Upper Cretaceous formations and faunas of southern California: Am. Assoc. Petroleum Geologists Bull., v. 26, no. 2, p. 162-187. Popenoe, W. P., Imlay, R. W., and Murphy, M, A., 1960, Correlation of the Cretaceous formations of the Pacific Coast (United States and northwestern Mexico): Geol. Soc. America Bull., v. 71, no. 10, p. 1491-1540. Post, W. $., 1928, Santa Ana investigation, flood control and conser- vation: California Dept. Public Works, Div. Engineering and Irrigation Bull. 19, p. 225-267. Revelle, Roger, and Fairbridge, Rhodes, 1957, Carbonates and car- bon dioxide, Chap. 10 of Hedgpeth, J. W., Ecology, v. 1 in Treatise on marine ecology and paleoecology: Geol. Soc. America Mem. 67, p. 239-295. Richmond, J. F., 1952, Geology of Burruel Ridge, northwestern Santa Ana Mountains, California: California Div. Mines Spec. Rept. 21, 16 p. Ross, C. S., and Kerr, P. F., 1931, The kaolin minerals: U. S. Geol. Survey Prof. Paper 165-E, p. 151-176. Saunders, N. E., 1958, Olive oil field, in A guide to the geology and oil fields of the Los Angeles and Ventura regions: Am Assoc. Petroleum Geologists, Pacific See., Ann. Mtg., 1958, p. 149- 151. Schoellhamer, J. E., Kinney, D. M., Yerkes, R, F., and Vedder, J. G., 1954, Geologic map of the northern Santa Ana Mountains, Orange and Riverside Counties, California: U. S. Geol. Survey Oil and Gas Inv. Map OM -154. Schoellhamer J, E., and Vedder, J. G., 1975, selected core holes and wells drilled for oil, in Vedder, J. G., Revised geologic map, structure sections, and well table, San Joaquin Hills - Capis- trano area, California: U. S. Geol. Survey Open-File Rept. 75- D69 552, 5 sheets. 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. Geol. Survey Oil and Gas Inv. Map OM -117, 2 sheets. Shelton, J. S., 1955, Glendora volcanic rocks, Los Angeles Basin, California: Geol. Soc. America Bull., v. 66, no. 1, p. 45-89. Silberling, N. J., Schoellhamer, J. E., Gray, C. H., Jr., and Imlay, R. W., 1961, Upper Jurassic fossils from Bedford Canyon forma- tion, southern California: Am Assoc. Petroleum Geologists Bull., v. 45, no. 10, p. 1746-1765. Singer, J. A., 1973, Geohydrology and artificial-recharge potential of the Irvine area, Orange County, California: U. S. Geol. Survey Open-File Rept. 5018-16, 41, p. Smith, P. B., 1960, Foraminifera of the Monterey Shale and Puente Formation, Santa Ana Mountains and San Juan Capistrano area, California: U. S. Geol. Survey Prof. Paper 254-M, p. 463-495. Sutherland, J. C., 1935, Geologic investigation of the clays of River- side and Orange Counties, southern California: California Jour. Mines and Geology, Rept. 31 of State Mineralogist. Vedder, J. G., 1957, New stratigraphic names used on geologic map of the San Joaquin Hills-San Juan Capistrano area, Orange County, California in Vedder, J. G., Yerkes, R. F., and Schoel- Ihamer, J. E., Geologic map of the San Joaquin Hills-San Juan Capistrano area Orange County, California: U. S. Geol. Oil and Gas Inv. Map OM-193. _- 1960, Previously unreported Pliocene Mollusca from the south- eastern Los Angeles basin: U. S. Geol. Survey Prof Paper 400-B, p. B326-B328. ___ 1972, Review of stratigraphic names and megafaunal correla- tion of Pliocene rocks along the southeast margin of the Los Angeles basin, California, in Stinemeyer, E H., ed., Pacific Coast Miocene Biostratigraphic Symposium: Soc. Econ. Paleontologists and Mineralogists, Pacific Sec., Bakersfield, Calif., March, 1972, p. 158-172. ___ 1975, Revised geologic map, structure sections, and well table, San Joaquin Hills-Capistrano area, California: U. S. Geol. Survey Open-file Rept. 75-552, 5 sheets. Vedder, J. G., Yerkes, R. F., and Schoellhamer, J. E., 1957, Geologic map of the San Joaquin Hills-San Juan Capistrano area, Orange County, California: U. S. Geol. Survey Oil and Gas Inv. Map OM-193, scale 1:24,000. Watts, W. L., 1897, Oil and gas yielding formation of Los Angeles, Ventura, and Santa Barbara Counties: California State Mining Bur. Bull. 11, 94 p. White, W. R., 1956, Pliocene and Miocene Foraminifera from the Capistrano Formation, Orange County, California: Jour. Paleontology, v. 30, p. 237-270. _- 1971, Biostratigraphy of the Capistrano Formation, Dana Point, California, in Berger F. W., ed., Geological guide book, Newport Lagoon to San Clemente, Orange County, California: Soc. Econ. Paleontologists and Mineralogists, Pacific Section, p. 50-54. Whitney, J. D., 1865, Geological survey of California: Geology, v. 1, Report of progress and synopsis of field work from 1869 to 1864. 498 p. Wissler, S. G., 1943, Stratigraphic formations [relations] of the pro- ducing zones of the Los Angeles basin oilfields: California Div. Mines Bull. 118, p. 209-234. Woodford, A. O., 1925, The San Onofre breccia; Its nature and ori- gin: California Univ. Pubs., Dept. Geol. Sci Bull., v. 15, no. 7, p. 159-280. Woodford, A. O., and Gander, Craig, 1977, Los Angeles erosion sur- face of middle Cretaceous age: Am. Assoc. Petroleum Geologists Bull., v. 61, no. 11, p. 1979-1990. D70 Woodford, A. O., McCulloh, T. H., and Schoellhamer, J. E., 1973, Paleogeographic significance of metatuff boulders in middle Tertiary strata, Santa Ana Mountains, California: Geol. Soc. America Bull., v. 83, no. 11, p. 3433-3436. Woodford, A. O., Welday, E. E., and Merriam, Richard, 1968, Sili- ceous tuff clasts in the upper Paleogene of southern Califor- nia: Geol. American Bull., v. 79, p. 1461-1486. Woodring, W. P., Bramlette, M. N., and Kew, W. S. W., 1946, Geol- ogy and paleontology of the Palos Verdes Hills, California: U. S. Geol. Survey Prof. Paper 207, 145 p. Woodring, W. P., and Popenoe, W. P., 1945, Paleocene and Eocene stratigraphy of northwestern Santa Ana Mountains, Orange County, California: U. S. Geol. Survey Oil and Gas Inv. Prelim. Chart 12. Woodring, W. P., Stewart, R. B., and Richards, R. W., 1940, Geology GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA of the Kettleman Hills oil field, California; Stratigraphy, paleontology, and structure: U. S. Geol. Survey Prof. Paper 195,170 p. Yerkes, R. F., 1957, Volcanic rocks of the El Modeno area, Orange County, California: U. S. Geol. Survey Prof. Paper 247-L, p. 313-334. --- 1972, Geology and oil resources of the western Puente Hills area, southern California: U. S. Geol. Survey Prof. Paper 420-C, 63 p. Yerkes, R. F., McCulloh, T. H., Schoellhamer, J. E., and Vedder, J. G., 1965, Geology of the Los Angeles basin, California - An introduction: U. S. Geol. Survey Prof. Paper 420 -A, 57 p. Zullo, V. A., and Durham, J. W., 1962, The echinoid genus Megapetalus Clark: Jour. Paleontology, v. 36, no. 3, p. 524- 528. SUPPLEMENTAL INFORMATION D72 GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA WELL LOCATIONS AND RELATED DATA [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 ] Operator Well Location Aeco Corp. Nohl-Bixby No. 1 1,000 S. and 400 W. of N.E. cor. sec. 12, T. 4 S., R. 9 W Amerada Petrol- eum Corp. Irvine No. 63-1 2,310 SW and 330 SE from the N. cor. of Irvine Ranch Block 63. Bixby No. 1 300 S. and 1,975 W. of NE. cor. see. 11, T. 4 S., R. 9 W. Bixby Hills Oil Co. 425 S. and 575 E. of NW. cor. proj. sec. 31, T. 3 S.. R. 9 W. California Eastern Verde No. 1 Oil Co. Carrey, A. A. Bixby-Nohl No. 1 2,300 N. and 2,150 E. of SW. cor. see. 9, T. 4 S., R. 9 W. 2,250 N. and 2,075 W. of SE. cor. see. 32, T. 3 S., R. 9 W. Anaheim Union Christopher Oil Co. Water No. 1 Doheny, Patrick A. Campbell No. 1 __ 2,450 N. and 2,200 E. of SW. cor. proj. sec. 35, T. 3 S., R. 9 W. Do. Stern No. 1 2,900 N. and 1,875 W. of SE. cor. proj. see. 35, T. 3 S., K. 9 W. Do. Stern No. 2 2,850 N. and 1,750 W. of SE. cor. proj. sec. 35, T. 3 S., R. 9 W Elev- ation 514 71 410% 255 480+ 235 335 399 399 Total depth 3,050 3,920 4,673 4,897 3,758 5,660 3,405 3,300 3,202 Spud 8/30/56 5/29/49 7/23/33 6/16/53 7/24/54 8/31/56 5/15/56 8/8/56 Present status Aban: doned 9/10/56 Aban: doned 6/18/49 Aban: doned 1/21/22 Aban- doned 12/11/36 Aban- doned 6/25/53 8/17/54 Aban: doned 9/10/56 Pro- ducing Pro- ducing Geology 0-1,590: Soquel Member of Puente Formation 1,590-1,930: La Vida Member of Puente Formation 1,930-2,640 +: Topanga Formation 2,640+-3,050: Vaqueros and Sespe Formations, undifferentiated 0-450 +: Alluvium 450 +-1,300+: La Habra (?) Formation with interbedded marine sedimentary rocks 1,300 +-2,220: Upper member of Fernando Formation 2,220-3,540: Puente Formation 3,540-3,920: Williams Formation 0-2: Alluvium ?-650 +: Lower member of Fernando Formation 650 +-3,200 +: Puente Formation 3,200 +-4,100+: Topanga Formation 4,100+-4,673: Vaqueros and Sespe Formations, undifferentiated 0-2: Terrace deposits ?-1,850 +: La Habra Formation 1,850+-3,500: Upper member of Fernando Formation 3,500-4,897: Lower member of Fernando Formation 0-140 +: Lower member of Fernando Formation 140+-1,500+: Yorba Member of Puente Formation 1,500+-1,760: Soquel Member of Puente Formation 1,760-2,100: La Vida Member of Puente Formation 2,100-3,100: Topanga Formation 3,100-3,758: Vaqueros and Sespe Formations, undifferentiated 0-2: Alluvium ?-1,010: La Habra Formation 1,010-2,190: Upper member of Fernando Formation 2,190-3,750: Lower member of Fernando Formation 3,750-3,978: Sycamore Canyon member of Puente Formation 3,978-5.038: Yorba Member of Puente Formation 5.038-5,660: Soquel Member of Puente Formation 0-2: Terrace deposits ?-420: Upper Member of Fernando Formation 420-1,430: Lower member of Fernando Formation 1,430-2,250: Sycamore Canyon Member of Puente Formation 2,250-3.265: Yorba Member of Puente Formation 2,320-2,637: Chapman sand in Yorba Member of Puente Formation 3,265-3,405: Soquel Member of Puente Formation 0-1,310: Lower member of Fernando Formation 1,310-2,240: Sycamore Canyon Member of Puente Formation 2,240-3,155:Yorba Member of Puente Formation 2,310-2,490: Chapman sand in Yorba Member of Puente Formation 3,155-3,300: Yorba Member of Puente Formation 0-1,285: Lower member of Fernando Formation 1,285-2,215: Sycamore Canyon Member of Puente Formation 2,215-3,163: Yorba Member of Puente Formation 2,280-2,533: Chapman sand in Yorba Member of Puente Formation 3,163-3,202: Soquel Member of Puente Formation Remarks Ditch sample at 480 reported to contain foraminifers of Pleistocene age. Ditch sample from 2,860 to 2,880 reported to contain foraminifers of the upper part of the Mohnian stage. Core from 3,729 to 3,749 reported to contain foraminifers of Late Cretaceous age. Driller's log only data available. Formerly known as Placentia Develop- ment Co. Verde No. 1. Bottom hole coordinates: 238 N. and 197 E. of surface location. Bottom hole coordinates: 240 N. and 199 E. of surface location. GEOLOGY OF THE SANTA ANA MOUNTAINS WELL LOCATIONS AND RELATED DATA-CONTINUED D73 [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 Operator Well Location Elev ation Total depth Spud Present status Geology Remarks Do. Drilling and Exploration Co. Do. Equality Oil Co. Gale, Hoyt S. General Petroleum Corp. Godfrey Drilling Co. Heffern Oil Co. Independent Exploration Co. Stern No. 3 (original hole) SE. cor. proj. sec. 35, T. 3 8.. R. 9 W. Stern No. 3 (redrill) 2.075 N. and.3,300 W. of SE. cor. sec. 32, T. 3 S., R. 9 W. Drilexco-State- Bennett No. 1 2,800 N. and 125 W. of SE. cor. sec. 32, T. 3 S., R. 9 W. Drilexco-State- Stern No. 1 2,550 NE. and 1,225 NW. from the S. cor. of Irvine Ranch Block 115. Irvine No. 1 Irvine No. 1 350 S. and 3,050 E. of NW. cor. see. 31, T. 5 S., R. 9 W Basin-Stern No. 1 2,125 N. and 1,550 E. of SW. cor. see. 33, T. 3 S., R. 9 W. Botiller No. 1 950 N. and 1,475 W. of SE. cor. proj. sec. 29, T. 3 S., R. 7 W. Heffern No. 1 1,750 N. and 725 W. of SE. cor. proj. sec. 31, T. 3 S., R. 9 W. South Placentia _ 100 N. and 2,025 W. of Community 30 SE. cor. proj. sec. 6, No. 1 T. 4 $., K. 9 W. 2,750 N. and 1,650 W. of 398 242 248 1,080+ 254 600+ 225+ 229 3,418 3,191 5,854 4,985 5,044 2,224 4,840 4,775 4,575 4,804 10/23/56 1/30/54 4/12/53 4/23/57 4/29/25 5/29/46 7/16/54 3/17/19 7/6/49 Aban- doned 11/11/56 Aban- doned 3/1/54 Pro- ducing Aban- doned 1958 Aban- doned 6/25 Pro- ducing Aban- doned 5/26/55 Aban- doned 10/23 Aban- doned 8/4/49 0-1,258: Lower member of Fernando Formation 1,258-2,190: Sycamore Canyon Member of Puente Formation 2,190-3,205 Yorba Member of Puente Formation 2,260-2,505 Chapman sand in Yorba Member of Puente Formation 3,205-3.418 Soquel Member of Puente Formation 0-1,260 +: Lower member of Fernando Formation 1,260 +-2.180: Sycamore Canyon Member of Puente Formation 2,180-3,130: Yorba Member of Puente Formation 2,240-2,505: Chapman sand in Yorba Member of Puente Formation 3,130-3,191: Soquel Member of Puente Formation 0-2: Alluvium ?-1,345: La Habra Formation 1,345-2.690: Upper member of Fernando Formation 2,690-4.142: Lower member of Fernando Formation 4,142-4,278: Sycamore Canyon Member of Puente Formation 4,278-5,350: Yorba Member of Puente Formation 5,350-5.854: Soquel Member of Puente Formation 0-2: Alluvium ?-700+: La Habra Formation 700+-1.950: Upper member of Fernando Formation 1,950-3,120: Lower member of Fernando Formation 3,120-3.318: Sycamore Canyon Member of Puente Formation 3,318-4,170: Yorba Member of Puente Formation 4,170-4,985: Soquel Member of Puente Formation 0-50 +: Terrace deposits 50+-350 +: Santiago Formation 350 +-1,450 +: Silverado Formation 1,150 +: Serrano Clay Bed 1,350 +: Claymont Clay Bed 1,450 +-1,600 +: Pleasants Sandstone Member of Williams Formation 1,600+-1,750+: Schulz Ranch Sand- stone Member of Williams Formation 1.750+-4,172+: Holz Shale Member of Ladd Formation 0-300 +: Alluvium 300 +-1,475+: Marine and non-marine sand, gravel, and clay of Pleistocene and possibly Pliocene age 1,475+-1,990 +Puente Formation or Monterey Shale 1,990+-2,224: Topanga Formation with interbedded volcanic agglomerate or breccia 0-2: Alluvium ?-750 +: La Habra Formation 750+-1.685: Upper member of Fernando Formation 1,685-2,950: Lower member of Fernando Formation 2,950-3,130: Sycamore Canyon Member of Puente Formation 3,130-4,020: Yorba Member of Puente Formation 4,020-4,840: Soquel Member of Puente Formation 0-1,840: Vaqueros and Sespe Formation, undifferentiated 1,840-2,685: Santiago Formation 2,685-4,500: Silverado Formation 4,500-4,775: Ladd Formation 0-2: Alluvium ?-1,035: La Habra Formation 1,035-2,285: Upper member of Fernando Formation 2,285-3,980: Lower member of Fernando Formation 3,980-4,804: Puente Formation Bottom hole coordinates; 346 N. and 444 E. of surface loca- tion. Bottom hole coordinates: 47 N. and 191 E. of surface location. In Richfield oil field. No data available below 4,172. To of Santiago Pea Volcanics report- ed at 4.810; and top of Bedford Canyon Formation reported at 4,997. Geology above 1,990 questionable, very poor data. "Sea Shells" reported between 410-625. In Richfield oil field. Formerly known as Basin Oil Co. Stern No. 1. No data available. D74 GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA WELL LOCATIONS AND RELATED DATA-CONTINUED [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 Operator Well Location Elev ation Total depth Spud Present status Geology Remarks Kesselman, Lyle E. Landess Oil Co. Lockhart, L. M. Long Beach Consolidated Oil Co. McKee Oil Co. Murdock, G. D. National Securities Oil Co. North Star Mining and Development Co. Olive Petroleum Co. Olive-Ventura il Corp. 275 S. and 150 E. of NW. cor. proj. see. 31, T. 3 S., R. 8 W. Kesselman- Yorba No. 1 Well No. 1 150 N. and 600 E. of SW cor. sec. 31, T. 3 S., R. 8 W. Budlong No. 1 1,725 S. and 750 W. of NE cor. proj. see. 34, Ww. T.38 Well No. 2 2,025 S. and 2,350 W. of NE. cor. sec. 9, T. 4 S., R. 9 W. Kokx Community 2,800 S. and 1,600 E. No. 8-1 of NW. cor. sec. 16, T. 4 S., R. 9 w. Howell No. 1 2,100 S. and 2,750 W. of NE. cor. sec. 1, T. 4 S., R. 9 w. Irvine No. 1 2,425 SW. and 600 NW. from the E. cor. of Irvine Ranch Block 17. Johnson No. 1 2,075 N. and 1,750 E. of SW. cor. sec. 8, T. 5 S., R. 7 w. 2,600 N. and 2,400 E. of SW. cor. see. 8, T. 4 S., R. 9 W. Well No. 1 Bixby No. 1 1,350 N. and 25 W. of SE. cor. sec. 9, T. 4 S., R. 9 W 328 3,217 400 3,119 278 6,016 440% _ 2,678 274 4,005 308 4,370 550% - 5,147 1440+ _ 490 240% _ 3,640 592 4,710 9/22/57 8/8/47 5/28/47 6/10/20 1/1/46 1/3/46 10/4/20 8/4/48 2/19/20 1/24/24 Aban: doned 10/3/57 10/7/47 Aban: doned 1/22/47 Aban- doned 5/21/21 Aban- doned 2/8/46 Aban- doned 3/9/48 Aban- doned 11/6/25 Aban- doned 5/31/49 Aban- doned 1922 Aban- doned 1925 0-2: Alluvium ?-1,300: Sycamore Canyon Member of Puente Formation 1,300-3,217: Yorba Member of Puente Formation 1,570-1,950: Chapman sand in Yorba Member of Puente Formation 0-1,130: Sycamore Canyon Member of Puente Formation 1,130-2,275; Yorba Member of Puente Formation 1,730-2,100: Chapman sand in Yorba Member of Puente Formation 2,275-3,119; Soquel Member of Puente Formation 0-2: Alluvium 2-950 +: La Habra Formation 950+-1,450: Upper member of Fernando Formation 1,450-2,030 +: Lower member of Fernando Formation 2,030 +-2,860: Sycamore Canyon Member of Puente Formation 2,860-4,100+: Yorba Member of Puente Formation 3,540+-3,930 +: Lower part of Chapman sand in Yorba Member of Puente Formation 4,100+-6,016: Soquel Member of Puente Formation 0-950 +: Lower member of Fernando Formation 950 +-2,678: Puente Formation 0-2: Alluvium ?-1,760+: La Habra Formation 1,760+-1,935: Upper member of Fernando Formation 1,935-2,145: Puente Formation 2,145-2,170+: El Modeno Volcanics 2,170+-3,710: Topanga Formation 3,710-4,005: Vaqueros and Sespe Formation, undifferentiate 0-100 +: Alluvium 100 +-815: Sycamore Canyon Member of Puente Formation 815-2,200: Yorba Member of Puente Formation 935-2,130: Chapman sand in Yorba Member of Puente Formation 2,200-3,505: Soquel Member of Puente Formation 3,505-3,895: La Vida Member of Puente Formation 3,895-4,370: Topanga Formation 0-50 +: Alluvium 50+-390 +: Vaqueros and Sespe Formation, undifferentiated 390 +-2,290+: Santiago Formation 2,290+-3,070+: Silverado Formation 3,070+-3,630 +: Pleasants Sandstone Member of Williams Formation 3,630+-3,975+: Schulz Ranch Sand- stone Member of Williams Formation 3,975+-5,147: Holz Shale Member of Ladd Formation 0-50 +: Terrace deposits 50+-490: Santiago Peak Volcanics 0-2: Alluvium ?-1,525+: La Habra Formation 1,525 +-2,167+: Upper member of Fernando Formation 2,167+-3,370+: Lower member of Fernando Formation 3,370+-3,640: Puente Formation 0-350 +: Lower member of Fernando Formation 350+-820 +: Yorba Member of Puente Formation 820+-1,475+: Soquel Member of Puente Formation 1,475+--2,350+: La Vida Member of Puente Formation 2,350+-3,500+: Topanga Formation 3,500+-4,710: Vaqueros and Sespe Formation, undifferentiated Driller's log only data available. Foraminifers and mollusks found in Topanga Formation. See locality m 182 and locality F 160. Driller's log only data available, interpretation very questionable. No data available, geology based on surface location. Driller's log only data available. Good driller's log only data avail- able. Also known as Eskridge and Craise Oil Co. Bixby No. 1. GEOLOGY OF THE SANTA ANA MOUNTAINS D75 WELL LOCATIONS AND RELATED DATA-CONTINUED {Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 ] Elev- Total Present Operator Well Location ation depth Spud status Geology Remarks Orange Community _ Forker No. 1 775 S. and 2,600 W. of 225+ 5,000% 9/27/23 Aban- _ 0-2: Alluvium Driller's log only Oil Association NE. cor. see. 29, T. 4 doned _ ?-1,640+: La Habra Formation data available. El S., R. 9 W. 5/8/24 1,640i 2,390 +: Puente Formation Modeno Volcanics 2,390+-3.600+: Topanga Formation may be represented 3,600 +-5,000 +: Vaqueros and Sespe in interval 2,390 + Formation, undifferentiated 2,510 +. May have bottomed in Santiago Formation. Owners Oil Monette No. 1 2,200 S. and 1,325 W. 580+ _ 2,880 9/20 Aban- Driller's log only Producers Co. of NE. cor. see. 24, doned data available, T. 4 S., R. 9 W. 1/28/25 no interpretation possible. Pacific Central Boisseranc No. 1 2,375 S. and 2,225 W. 268 4,366 6/30/45 Aban- _ 0-2: Alluvium Oil Co. of NE. cor. pm] sec. doned _ ?-945 +: La Habra Formation 34, T. 3 S.. R. 9 W. 9/26/45 945+-1,600: Upper member of Fernando Formation 1,600-2,410: Lower member of Fernando Formation 2,410-2,900: Sycamore Canyon Member of Puente Formation 2,900-4,240: Yorba Member of Puente Formation 2,980-4,050+: Chapman sand in Yorba Member of Puente Formation 4,240-4,366: Soquel Member of Puente Formation Red Star Oil Co. Ward Associates _ 275 SE. and 200 SW. 66+ 5,247 7/16/56 Aban- - 0-2: Alluvium No. 1 from the N. cor. of doned _ ?-2,510: Marine and nonmarine sand, Irvine Ranch Block 9. 8/13/56 gravel, and silt of Pleistocene and possibly Pliocene age 2,510-3,140: Puente Formation or Monterey Shale 3,140-4,465: Topanga Formation 4,465-5,247: Vaqueros and Sespe Formation, undifferentiate Richfield Oil Hamrick-Olive 300 S. and 2,000 W. of 230% - 2,679 - 8/26/44 Aban- _ 0-2: Alluviam Corp. No. 1 NE. cor. see. 8, T. 4 doned _ ?-610+: Upper member of S., R. 9 w. 10/7/44 Fernando Formation 610 +-2,050 +: Lower member of Fernando Formation 2,050+-2,679: Puente Formation Do. Mohawk-Kraemer 75 N. and 1,825 E. of 660+ _ 4,208 5/21/45 Aban- _ 0-2,600: Sycamore Canyon Member No. 1 SW. cor. proj. see. 25 doned of Puente Formation T. 3 S.. R. 9 W. 6/28/45 2,600-3,580; Yorba Member of Puente Formation 2,675-2,720: Chapman sand in Yorba Member of Puente Formation 3,580-4,208: Soquel Member of Puente Formation Do. Peralta Hills 1,400 N. and 2,675 E. 392 4,605 1/23/50 Aban- _ 0-880: Lower member of No. 1 of SW. cor. sec. 3, doned Fernando Formation T. 4 S., R. 9 W. 2/21/50 880-1,320: Sycamore Canyon Member of Puente Formation 1,320-1,980: Yorba Member of Puente Formation 1,980-4,320: Soquel Member of Puente Formation 4,320-4,605: La Vida Member of Puente Formation Rubicon Oil Co. Wilcox No. 1 1,200 S. and 925 E. of 450 6,325 5/8/47 Aban- _ 0-75+: Terrace deposits NW. cor. see. 6, T. 4 doned 15+ 515: Sycamore Canyon Member S., R. 8 W. 6/22/47 of Puente Formation 515-1,600: Yorba Member of Puente Formation 900-1,305: Chapman sand in Yorba Member of Puente Formation 1,600-3,205: Soquel Member of Puente Formation 3,205-3,700: La Vida Member of Puente Formation 3,700-4,330: Topanga Formation 4,330-5,780: Vaqueros and Sespe Formation, undifferentiate 5,780-6,325: Santiago Formation Santa Ana Canyon Crowthers No. 1 _ 1,875 N. and 800 E. of 440% _ 4,165 7/14/19 Aban- _ 0-50 +: Terrace deposits Driller's log Oil Co. W. cor. proj. sec. 32, doned _ 50+-220+: Sycamore Canyon Member only data T. 3 S., R. 8 W. 12/17/20 of Puente Formation available. 220 +-1,210 +: Yorba Member of Puente Formation 1,210+-2,200 +: Soquel Member of Puente Formation 2,200+-3,050+: La Vida Member of Puente Formation 3,050+-3,960+: Topanga Formation 3,960+-4,165: Vaqueros and Sespe Formation, undifferentiated D76 GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA WELL LOCATIONS AND RELATED DATA—CONTINUED [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 Elev- Total Present Operator Well Location ation depth Spud status Geology Remarks Seaboard Oil Co. Christensen No. 1 800 S. and 1,550 W. of 245 5,110 10/6/48 Aban- - 0-2: Alluvium NE. cor. see. 5, T. 4 doned _ ?-1,410: La Habra Formation S., R. 9 W. 11/7/48 1,410-3,210: Upper member of Fernando Formation 3,210-4,280: Lower member of Fernando Formation 4,280-4,370: Sycamore Canyon Member of Puente Formation 4,370-5,1 10; Yorba Member of Puente Formation Shell Oil Co. Allec No. 1 2,800 S. and 975 E. of 236 5.656 5/23/27 Aban- _ 0-2: Terrace deposits NW. cor. proj. see. 31, doned _ ?-3 830+ La Habra Formation T. 3 S., R. 9 W. 1/12/28 3,830+-4,940+: Upper member of Fernando Formation 4,940+-5,656: Lower member of Fernando Formation Do. Irvine Core 1,300 SW. and 575 SE. 440 893 12/6/49 Aban- _ 0-460: Williams Formation Hole No. 1 from the N. cor. of doned _ 460-893: Holz Shale Member of Ladd Irvine Ranch Block 142. 12/29/49 Formation Do. Irvine Core 575 SW. and 2.650 SE. 301 1,008 _ 12/30/49 _ Aban- 0-2: Alluvium Hole No. 2 from the N. cor. of doned _ ?-710: La Habra Formation(?) Irvine Ranch Block 121. 1/19/50 710-1,008: Williams Formation Do. Irvine Core 2,575 SW. and 2,575 82 2.006 1/20/50 Aban- _ 0-305+: Alluvium Hole No. 3 SE. from the N. cor. of doned _ 305-905: La Habra Formation ?) Irvine Ranch Block 86. 2/20/50 905-2,006: Vaqueros and Sespe Formation, undifferentiated Do. Irvine Core 1,250 NE. and 1,450 184 2,615 6/15/50 Aban- - 0-2: Alluvium Hole No. 4 SE. from the W. cor. of doned _ ?-1,060+: La Habra Formation( ?) Irvine Ranch Block 105. 7/15/50 1,060 Vaqueros and Sespe Formation, undifferentiated 1,980-2,435: Williams Formation 2,435-2.615: Holz Shale Member of Ladd Formation Do. Irvine Core 2,250 SE. and 3,200 284 3.263 2/25/50 Aban- - 0-2: Alluvium Hole No. 5 SW. from the N. cor. of doned _ 2-790: La Habra Formation{(?) Irvine Ranch Block 121. 4/1/50 - 790-1,185: Williams Formation 1,185-3.048: Holz Shale Member of Ladd Formation 3,048-3,263: Baker Canyon Conglomerate Member of Ladd Formation Do. Irvine Core 1,800 NW. and 2,400 330 1,546 5/30/50 Aban- - 0-2: Alluvium Hole No.12 NE. from the S cor. doned _ ?-748: La Habra Formation (?) of Irvine Ranch Block 6/14/50 748-1,546: Holz Shale Member of Ladd 120. Formation Do. Travis No. 1 325 S. and 1,550 W. of 357 6,158 7/11/54 Aban- _ 0-2: Alluvium NE. cor. proj. sec. 36, doned _ ?-1,190: Sycamore Canyon Member T. 3 S., R. 9 W. 9/14/54 of Puente Formation 1,190-3,480: Yorba Member of Puente Formation 1,355-1,503: Chapman sand in Yorba Member of Puente Formation 3,480-4,618: Soquel Member of Puente Formation 4,618-5,765: La Vida Member of Puente Formation 5,765-6,158: Topanga Formation Shoreline Oil Co. Pinkerton No. 1 _ 2,325 S. and 2,150 W. 187+ - 3,625 - 8/23/27 Aban- _ 0-2: Alluvium Also known as of NE. cor sec. 5, T. doned _ ?-1,100 +: La Habra Formation C. A. Son Orangeana 5 S., R. 9 W. 1/31/29 1,100+-1,816+: Upper member of No. 1. Fernando Formation 1,816+-2,500+: Vaqueros and Sespe Formations, undifferentiated 2,500 +-3,625: Santiago Formation Spook Oil Co. Stockwell Pool __ 1,200 N. and 5,050 E. 258 - 6,285 - 7/30/53 - Aban- 0-2: Alluyvium Formerly known as No. 1 fSW cor sec. 33, T. doned _ ?-1,460 +: La Habra Formation Burhess Oil Co. 3 S., 7/8/54 1,460 Upper member of Stockwell Pool Fernando Formation No. 1. 2,550-3,580 +: Lower member of Fernando Formation 3,580 +-3,935: Sycamore Canyon Member of Puente Formation 3,935-4,950: Yorba Member of Puente Formation 4,950-6,285: Soquel Member of Puente Formation Standard Oil Co. Anaheim Union _ 2,250 N. and 500 W. of 362 4,718 _ 10/18/18 _ Aban- Driller's log only Water No. 1 E. cor. proj. sec. 35, doned data available, T. 3 S., R. 9 W. 12/28/19 no interpretation possible. Do. Bixby No. 1 525 N. and 1,050 E. of 345+ - 3,300 _ 2/20/13 Aban 0-200 +: Upper member of Driller's log only SW. cor. sec. 9, T. 4 S., R. 9 w. ned Fernando Formation 2/14/14 200 +-400 +: Lower member of Fernando Formation 400 +-1,860+: Puente Formation 1,860+-3,300 +: Topanga Formation data available, interpretation questionable. GEOLOGY OF THE SANTA ANA MOUNTAINS D77 WELL LOCATIONS AND RELATED DATA-CONTINUED [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 ] Elev- Total Present Operator Well Location ation depth Spud status Geology Remarks Do. Edwards 1,350 S. and 725 E. of 330 4,350 _ 10/28/34 Pro- - 0-2: Terrace deposits In Richfield oil Community No. 1 _ NW. cor. proj. see. 34, ducing - ?-510+: La Habra Formation field. T. 3 S.. R. 9 W. 510+-975: Upper member of Fernando Formation 975-2,220: Lower member of Fernando Formation 2,220-2.775: Sycamore Canyon Member of Puente Formation 2,175-4,170: Yorba Member of Puente Formation 2.875-3,820: Chapman sand in Yorba Member of Puente Formation 4,170-4,350: Soquel Member of Puente Formation Do. Kraemer No. 2-25 300 N. and 2,275 W. of 270 4,500 5/27/37 Pro- _ 0-2: Terrace deposits Do. SE. cor. sec. 29, T. ducing - ?-1,100: La Habra Formation 3 S., R. 9 W. 1,100-1,920: Upper member of Fernando Formation 1,920-2,815: Lower member of Fernando Formation 2,815-2,990: Sycamore Canyon Member of Puente Formation 2,990-3,800: Yorba Member of Puente Formation 3,085-3,315: Chapman sand in Yorba Member of Puente Formation 3,800-4,500: Soquel Member of Puente Formation Do. Locke No. 1 2,500 N. and 1,550 W. 368 3,795 11/3/18 Aban- Driller's log only of SE. cor. proj. sec. doned data available, 35, T. 3 S., R. 9 W. 4/1/20 no interpretation possible. Do. Locke No. 2 1,500 S. and 750 W. of 530 4,006 71/3/19 Aban- Do. NE. cor. proj. see. 35, doned T. 3 S.. R. 9 W. 7/24/20 Do. Southeas 2,050 N. and 450 W. of 281 4,400 1/8/45 Aban- - 0-2: Alluvium Rlchfield Unit SE. cor. proj. see. 34, doned _ ?-695+: La Habra Formation No. 1 T. 3 S.. R. 9 W. 2/8/45 695+-1,110: Upper member of Fernando Formation 1,110-2,088: Lower member of Fernando Formation 2,088-2,750: Sycamore Canyon Member of Puente Formation 2,750-3,735: Yorba Member of Puente Formation 2,800-3,650: Chapman sand in Yorba Member of Puente Formation 3,735-4 400: Soquel Member of Puente Formation Do. Taft Community - 250 S. and 1,275 W. 242 3,095 7/8/48 Aban- - 0-2: Alluvium No. 1 of NE. cor. see. 20, doned _ ?-2,315: La Habra Formation T. 4 S., R. 9 W. 8/6/48 - 2,315-2,445: Upper member of Fernando Formation 2,445-3,006: Puente Formation 3,006-3,095: El Modeno Volcanics Do. Tustin Commumty 600 N. and 1,350 E. of 271 2,380 _ 8/23/47 Aban- - 0-2: Alluvium No. SW. cor. see. 21, T. 4 doned _ ?-1,678: La Habra Formation S., R. 9 W. 9/12/47 1,678-2,332: Puente Formation 2,332-2,380: El Modeno Volcanics Do. Yorba Commumty 1,150 S. and 1,250 W. of 317 2,714 _ 9/10/35 Aban- _ 0-2: Alluvium Redrilled 3 No. E cor prokvsec 36, doned _ ?-1,500 +: Sycamore Canyon Member times. 5/23/36 of Puente Formation 1,500+-2,714: Yorba Member of Puente Formation Do. Zaiser-Brelje 2,250 S. and 1,300 E. 210 5,045 6/21/27 Aban- - 0-2: Alluvium Community No. 1 of NW. cor. see. 17, T. doned _ ?-2,150 +: La Habra Formation 4 S., R. 9 W. 11/26/27 2,150 +-3,230: Upper member of Fernando Formation 3,230-3,835: Puente Formation 3,835-4,340: Topanga Formation 4,340-4,450: Intrusive volcanic rocks related to El Modeno Volcanics 4,450: Fault 4, 450-4,740: Vaqueros and Sespe Formations, undifferentiated 4,740-4,750: Intrusive volcanic rocks related to El Modeno Volcanics 4,750-5,045: Vaqueros and Sespe Formations, undifferentiated Stephens, J. J. Susie M-1 450 N. and 3,875 W. of 1,090% 4,363 12/16/55 Idle _ 0-75%: Alluvium Also known as J. J. SE. cor. sec. 7, T. 5 1/59 _ 75-610: Silverado Formation Stephens- S.,. R. 7 W. 610-980: Pleasants Sandstone Member of Silverado Williams Formation Exploration Co. 980-1,360: Schulz Ranch Sandstone Susie M-1 and Member of Williams Formation Grandeur Ex- 1,360-3,575+: Holz Shale Member of loration Co. Ladd Formation usie M-1. D78 GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA WELL LOCATIONS AND RELATED DATA-CONTINUED [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 *~» Elev ation Total depth Present Operator Well Location Spud status Geology Remarks Stephens, J.J. -Continued Sudduth Drilling Century- Wetzel Co. No. 18 Superior Oil Co. Bennett No. 1 Do. Davis No. 1 Do. Schroeder No. 1 Bennett No. 1 (Original hole) Texas Co. Bennett No. 1 (Redrill No. 1) Bennett No. 1 (Redrill No. 2) Do. Carrillo Ranch (NCT-1) No. 1 Do. Dowling No. 1 Do. Dowling No. 2 1,200 S. and 1,500 W. of NE. cor. sec. 32, T. 3 S., R. 9 W. 1,150 N. and 2,200 W. of SE. cor. sec. 32, T. 3 S., R. 9 W. 1,850 S. and 2,000 W. of NE. cor. proj. see. 6, T. 4 S., R. 9 w. 150 N. and 3,250 E. of W. cor. sec. 33, T. 3 S., R. 9 w. 1,275 N. and 2,075 W. of SE. cor. sec. 32, T. 3 S., R. 9 w. 875 N. and 3,850 E. of SW. cor. proj. sec. 30, T. 3 S.. R.8 W. 2,350 S. and 3,050 E. of NW. cor. proj. see. 31, T. 3 S., R. 9 W. 2,200 S. and 3,900 E. of W. cor. proj. see. 31, T. 3 S., R. 9 W. 280 238 222 255 245 375 243 244 3,575 +-3,830+: Baker Canyon Conglomer- 5,150 4,162 1418 4,514 6,022 7,385 8,298 4,507 8,115 8,094 9 9/28/29 11/13/29 9/15/29 3/8/57 6/16/53 6/27/56 10/27/56 Aban- doned pro- ducer Aban- doned 11/26/29 Aban- doned 12/2/29 Aban- doned 10/27/29 Aban- doned 6/19/57 Aban- doned 7/10/53 Pro- ducing dors ate Member of Ladd Formation 3,830+-4,300 +: Trabuco Formation 4,300 +-4,363: Probably either Santiago Peak Volcanics or Bedford Canyon Formation 0-?: Terrace deposits ?-1,450: La Habra Formation 1,450-2,370: Upper member of Fernando Formation 2,370-3,400: Lower member of Fernando Formation 3,400-3,630: Sycamore Canyon Member of Puente Formation 3,630-4,560: Yorba Member of Puente Formation 4,560-5,150: Soquel Member of Puente Formation 0-2: Alluvium ?-1,050 +: La Habra Formation 1,050+-2,230+: Upper member of Fernando Formation 2,230 +-4,162: Lower member of Fernando Formation 0-2: Alluvium ?-1,418: La Habra Formation 0-2: Alluvium 2-970; La Habra Formation 970-2,210: Upper member of Fernando Formation 2,210-3,670: Lower member of Fernando Formation 3,670-3,910: Sycamore Canyon Member of Puente Formation 3,910-5,600 +: Yorba Member of Puente Formation 5,600 +-6,022: Soquel Member of Puente Formation ?-3,910: Sycamore Canyon Member of Puente Formation 3,910-5,710: Yorba Member of Puente Formation 5,710-7,385: Soquel Member of Puente Formation ?-5,913: Yorba Member of Puente Formation 5,913-7,820: Soquel Member of Puente Formation 7,820-8,225; La Vida Member of Puente Formation 8,225-8,298: El Modeno Volcanics 0-2: Alluvium ?-1,535: Sycamore Canyon Member of Puente Formation 1,535-2,958: Yorba Member of Puente Formation 1,656-1,837: Chapman sand in Yorba Member of Puente Formation 2,958-3,550: Soquel Member of Puente Formation 3,550-4,050: La Vida Member of Puente Formation 4,050-4,507: Topanga Formation 0-2: Alluvium ?-1,780: La Habra Formation 1,780-2,785: Upper member of Fernando Formation 2,785-5,410: Lower member of Fernando Formation 5,410-5,700: Sycamore Canyon Member of Puente Formation 5,700-6,950 +: Yorba Member of Puente Formation 6,950+-8,115: Soquel Member of Puente Formation 0-2: Alluvium ?-1,495: La Habra Formation 1,495-2,545: Upper member of Fernando Formation 2,545-4,650: Lower member of Fernando Formation 4,650-4,845: Sycamore Canyon Member of Puente Formation 4,845-6,650 +: Yorba Member of Puente Formation 6,650 +-8,094: Soquel Member of Puente Formation In Richfield oil field. Driller's log only data available. Do. Driller's log only data available, no interpretation possible. Bottom hole coordinates: 496 N. and 701 W. of surface location. Bottom hole coordinates: 307 N. and 909 W. of surface location. Bottom hole coordinates: 43 N. and 1,104 W. of surface location. Lower member of Fernando Formation believed to be repeated by a northwest trend- ing, northeast dipping, reverse fault. Lower member of Fernando Formation believed to be repeated by a northwest trend- ing, northeast dipping, reverse fault. GEOLOGY OF THE SANTA ANA MOUNTAINS D79 WELL LOCATIONS AND RELATED DATA-CONTINUED [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 ] Elev- Total Present Operator Well Location ation _ depth Spud status Geology Remarks Do. Hodges No. 1 1,675 S. and 950 E. of 206 7,075 10/16/58 Aban- _ 0-2: Alluvium NW. cor. proj. see. 7, doned _ ?-1,310: La Habra Formation T. 4 S., R. 9 W. 1/15/54 1,310-3,275; Upper member of Fernando Formation 3,275-5,750: Lower member of Fernando Formation 5,150-6,875: Puente Formation 6,875-7,075: Topanga Formation Do. Irvine (NCT-1) 800 NE. and 675 NW. 701 3,523 5/1/52 Aban- _ 0-2: Terrace deposits No. 1 from the S. cor. of doned _ ?-585; Pleasants Sandstone Member of Irvine Ranch Block 19 6/3/52 Williams Formation 585-1,630: Schulz Ranch Sandstone Member of Williams Formation 1,630-3,375: Holz Shale Member of Ladd Formation 3,375-3,523: Baker Canyon Conglomerate Member of Ladd Formation Do. Irvine (NCT-1) 1,275 SW. and 2,300 350 4,997 1/13/58 Aban- _ 0-50+: Alluvium No. 1 NE. from the E. cor. doned _ 50+-495: Santiago Formation of Irvine Ranch Block 66 3/4/53 - 495-1,160: Silverado Formation 1,160-1,950: Williams Formation 1,950-4,600: Holz Shale Member of Ladd Formation 4,600-4,997: Bedford Canyon Formation Do. Kraemer No. 1 1,075 S. and 975 E. of 266 8,510 10/16/55 _ Aban- - 0-?: Terrace deposits Lower member of NW. cor. proj. see. 31, doned _ ?-1,800: La Hag“; Formation Fernando T. 3 S., R. 9 W. 8/13/56 1,800-3,170: Upper member of Formation Fernando Formation believed to be 3,170-6,270: Lower member of repeated by a Fernando Formation northwest trend - 6,270-6,333: Sycamore Canyon Member ing, northeast of Puente Formation dipping reverse 6,333-7,490+: Yorba Member of fauft. edrilled Puente Formation from 6,593- 7,490+-8,510: Soquel Member of 7,756. Puente Formation Do. Olive Community 1,975 S. and 2,150 E. 216 5,431 12/12/30 _ Aban- 0-?: Alluvium No. 1 of NW. cor. proj. see. 7, doned _ ?-1,400+: La Habra Formation T. 4 S., R. 9 W. 5/28/31 1,400+-3,100+: Upper member of Fernando Formation 3,100+-5,190+: Lower member of Fernando Formation 5,190+-5,431: Puente Formation Do. Olive Unit One 450 S. and 125 E. of 216 7,392 _ 2/22/53 Pro- _ 0-2: Alluvium In Olive oil field. No. 1 NW. cor. proj. sec. 7, ducing _ ?-1,565: La Habra Formation Formerly known T. 4 S., R. 9 d] 1,565-4,080: Upper member of as Texas Co. Fernando Formation Dinkler No. 1. 4,080-6,060: Lower member of Fernando Formation 6,060-7,070: Puente Formation 7,070-7,392: Topanga Formation Do. Olive Unit One 325 S. and 975 E. of 220 5,885 _ 6/26/53 --do-- _ 0-?: Alluvium In Olive oil field. No. 2 W. cor. proj. sec. 7, ?-1,420+: La Habra Formation T. 4 S., R. 9 W. 1,420+-3,750: Upper member of Fernando Formation 3,750-5,830: Lower member of Fernando Formation 5,830-5,885: Puente Formation Do. Olive Unit Two 1,200 S. and 525 E. of 219 5,720 _ 4/28/54 Aban- _ 0-2: Alluvium No. 1 NW. cor. proj. sec. 7, doned _ ?-1,410: La Habra Formation T. 4 S., R. 9 W. 5/24/54 1,410-3,655: Upper member of Fernando Formation 3,655-5,720: Lower member of Fernando Formation Do. Placentia Unit 1,425 N. and 475 W. of 252 5,495 12/14/54 _ Aban- 0-2: Alluvium One (NCT-1) SE. cor. sec. 32, T. 3 doned _ ?-755+: La Habra Formation No. 1 S., R. 9 W. 1/5/55 - 755+-1,375: Upper member of Fernando Formation 1,375-3,992: Lower member of Fernando Formation 3,992-4,210: Sycamore Canyon Member of Puente Formation 4,210-5,230: Yorba Member of Puente Formation 5,230-5,495: Soquel Member of Puente Formation > Do. Ragan (NCT-1) 750 N. and 1,375 W. 392 5,690 1/10/54 Aban- - 0-150: Terrace deposits INFO. 1 of SE. cor. see. 15, doned - 150-405: Puente Formation T. 4 S., R. 9 W. 2/18/54 405-740: El Modeno Volcanics 740-1,850: Topanga Formation 1,850-3,605: Vaqueros and Sespe Formations, undifferentiated 3,605-4,650+: Santiago Formation and possibly Silverado Formation 4,650 +: Norwalk fault 4,650 +-4,900: Schulz Ranch Sandstone Member of Williams Formation 4,900-5,690: Holz Shale Member of Ladd Formation D80 [Wildcat wells, core holes, and selected producing GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA WELL LOCATIONS AND RELATED DATA-CONTINUED names are those in use in 1958 wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's Operator Well Location Elev- ation Total depth Spud Present status Geology Remarks Do. Do. Do. Tidewater Oil Co. Trustees Develop- ment Association Union Oil Co. Richfield Consolidated No. 19 Ruff No. 1 Vejar No. 1 Ibbetson No. 1 Olive-Orange No. 1 Wents No. 1 Well No. 1 Chapman No. 29 1,950 S. and 1,100 W. of NE. cor. proj. sec. 33. T. 3 8.. 8. 9 W. 1,300 N. and 75 W. of SE. cor. proj. see. 1, T. 3 S., R. 10 W. 2,450 N. and 1,825 E. of SW. cor. proj. see. 35, T. 3 S., K. 9 W. 1,225 N. and 1,125 E. of SW. cor. proj. sec. 35, T.3 $.. K. 9 W. 2,100 S. and 425 E. of NW. cor. see. 19, T. 4 S., R. 9 W. 225 S. and 1,025 E. of NW. cor. proj. see. 31, T. 3 S., R. 9 W. 450 S. and 1,500 W. of NE. cor. see. 6, T. 5 S., R. 9 W. 1,325 N. and 2,550 W. of SE. cor. sec. 29, T. 3 S., R. 9 W. 265 217 327 280 178 260+ 185+ 290 4,450 8,497 3,564 3,358 4,509 4,128 4,144 10,496 7/13/53 4/30/54 5/7/46 1/19/19 3/15/41 2/21 6/12/25 3/7/36 Pro- ducing Aban- doned 6/10/54 Aban- doned 6/5/46 Aban- doned 1/10/20 Aban- doned 5/27/41 Aban- doned 1/6/23 Aban- doned 8/19/25 Pro- ducing 0-2: Alluvium 2-770: La Habra Formation 770-1,380: Upper member of Fernando Formation 1,380-2,180: Lower member of Fernando Formation 2,180-2.600: Sycamore Canyon Member of Puente Formation 2,600-4,240: Yorba Member of Puente Formation 2,770-3.840: Chapman sand in Yorba Member of Puente Formation 4,240-4,450: Soquel Member of Puente Formation In Richfield oil field. 0-2: Alluvium ?-1,850: La Habra Formation 1,850-5.265+: Upper member of Fernando Formation 5.265 Lower member of Fernando Formation 6,646-7,450:; Puente Formation 7,450-8,057: Topanga Formation 497: Vaqueros and Sespe Formations, undifferentiated 0-2: Terrace deposits ?-530: Upper member of Fernando Formation 530-1, 480+: Lower member of Fernando Formation 1,480 +: Sycamore Canyon Member of Puente Formation 2,310 +-3,100 +: Yorba Member of Puente Formation 2,425-2.650: Chapman sand in Yorba Member of Puente Formation 3,100+-3,564: Soquel Member of Puente Formation 0-65 +: Alluvium 65+-525 +: La Habra Formation 525+-1,300 +: Upper member of Fernando Formation 1,300+-2,320+: Lower member of Fernando Formation 2,320 +-2,860 +: Sycamore Canyon Member of Puente Formation 2,860 +-3,358: Yorba Member of Puente Formation Formerly known as Amalgamated Oil Co. Ibbetson No. 1. 0-2: Alluvium ?-2,420: La Habra Formation 2,420-3,320: Upper member of Fernando Formation 3,320-3.670: Lower member of Fernando Formation 3,670-4,108: Puente Formation 4,108-4,366: Topanga Formation 4,366-4,509: El Modeno Volcanics 0-2: Terrace deposits ?-1,900+: La Habra Formation 1,900 +-2.935: Upper member of Fernando Formation 2,935-4,128: Lower member of Fernando Formation Driller's log only data available. Formerly known as Placentia Pacific Oil Co. and Amalgamated Oil Co. Wents No. 1. Driller's log only data available. 0-2: Alluvium ?-1,350 +: La Habra Formation 1,350+-2,100+: Upper member of Fernando Formation 2,100 +-2,120 +: El Modeno Volcanics 2,120+-2,600+: Topanga Formation 2,600+-3,350 +: Vaqueros and Sespe Formations, undifferentiated 3,350 +-4,144: Santiago Formation 0-?: Terrace deposits ?-1,008: La Habra Formation 1,008-1,888: Upper member of Fernando Formation 1,888-2,600: Lower member of Fernando Formation 2,600-2,783: Sycamore Canyon Member of Puente Formation 2,783-3,925: Yorba Member of Puente Formation 2,916-3.485: Chapman sand in Yorba Member of Puente Formation 3,925-6,820: Soquel Member of Puente Formation 6,820-7,910 +: La Vida Member of Puente Formation 7,910 +-8,140 +: El Modeno Volcanics 8,140 +-9,130: Topanga Formation 9,130-10,496: Vaqueros and Sespe Formations, undifferentiate In Richfield oil field. GEOLOGY OF THE SANTA ANA MOUNTAINS WELL LOCATIONS AND RELATED DATA-CONTINUED D81 [Wildcat wells, core holes, and selected producing wells drilled in the northern Santa Ana Mountains before January 1, 1959. Elevations, depths, and locations are in feet, and the operator's names are those in use in 1958 ] Operator Well Elev ation Location Total depth Spud Present status Geology Remarks Do. Olive Community 100 N. and 175 E. of No. 4-1 S Do. Yorba No. 1 Universal Con- C and T No. 1 solidated Oil Co. Do. Wiley No. 1 (original hole) Wiley No. 1 (redrill) West American Irvine No. 1 Co. Wheelock, Collins, _ Travis No. 1 Abercrombie, and Porter 209 . cor. sec. 8, T. 4 S., R. 9 W. 950 S. and 1,000 W. 2715+ of NE. cor. proj. sec. 34, T. 3 S., R. 9 W 1,150 S. and 4,125.W. of NE. cor. see. 5, T. 4 S., R. 9 W. 237 2,400 S. and 3,550 W. of NE. cor. see. 5, T. 4 S., R. 9 W. 239 150 NW. and 1,300 142+ NE. from the S. cor. of Irvine Ranch Block 43. 250 S. and 2,450 E. of 342 NW. cor. proj. sec. 31, T. 3 S., R.8 W 4,236 2,997 6,969 6,637 5,165 6,052 3,150 9/6/48 10/30/20 11/11/47 5/2/48 4/26/37 3/12/48 Aban- doned 10/6/48 Aban: doned 9 Aban- doned 1/20/48 Aban: doned 7/13/48 9/18/37 Aban- doned 1948 0-2: Alluvium ?-2,300 +: La Habra Formation 2,300 +-3,450: Upper member of Fernando Formation 3,450-3,722: Lower member of Fernando Formation 3,722-4,086: Puente Formation 4,086-4,160 +: El Modeno Volcanics 4,160 +: Norwalk fault 4,160 +-4,236: Vaqueros and Sespe Formations, undifferentiated 0-2: Alluvium ?-1,765: La Habra Formation 1,765-3,945: Upper member of Fernando Formation 3,945-5,540: Lower member of Fernando Formation 5,540-6,905: Yorba Member of Puente Formation 6,905-6,969: Soquel Member of Puente Formation 0-2: Alluvium ?-1,270: La Habra Formation 1,270-2,895: Upper member of Fernando Formation 2,895-4,490: Lower member of Fernando Formation 4,490-5,680 +: Yorba Member of Puente Formation 5,680 +-6,120 +: Soquel Member of Puente Formation 6,120+-6,637: La Vida Member of Puente Formation 1,270-2,892: Upper member of Fernando Formation 2,892-4,845: Lower member of Fernando Formation 4,845-5,165: Yorba Member of Puente Formation 0-2: Alluvium ?-1,034+: La Habra Formation(?) 1,034+-2,970 +: Rocks of unknown age and correlation 2,970 +-3,840: Williams Formation 3,840-5,750 +: Holz Shale Member of Ladd Formation 5,750 +-6,052: Bedford Canyon Formation (?) or Santiago Peak Volcanics (?) 0-2: Alluvium ?-1,730: Sycamore Canyon Member of Puente Formation 1,730-3,110: Yorba Member of Puente Formation 1,840-2,050: Chapman sand in Yorba Member of Puente Formation 3,110-3,150: Soquel Member of Puente Formation No data available. Bottom hole coordinates; 477 N. and 277 W. of surface location. Upper Cretaceous ossils reported in cores below 3,550. Cores of "basement" rock described as serpentine and andesite, no samples available. D82 LIST OF MEGAFOSSILS LATE CRETACEOUS LADD FORMATION BAKER CANYON CONGLOMERATE MEMBER Fossils identified by W. P. Popenoe, 1951-54, with some nomenclatural revisions in 1977, and arranged in approximate stratigraphic order. (For locality descrip- tions and U.S. Geological Survey locality numbers see megafossil locality list.) Locality F1 Pelecypods Lima beta Popencoe Trigonarca californica Packard Locality Fla Gastropods Ampullina pseudoalveata (Packard) Gyrodes dowelli White Pelecypods Ambocardia delta (Popenoe) "'Astarte'' sulcata Packard Trigonarca californica Packard Locality F1b Gastropods Ampullina pseudoalveata (Packard) Anchura cf. A. condoniana Anderson Pelecypods Ambocardia delta (Popenoe) "Aphrodina" arata (Gabb) Clisocolus corrugatus Popenoe Cucullaea gravida (Gabb) Glycymeris pacificus (Anderson) Lima beta Popenoe Pterotrigonia klamathonia (Anderson) Tenea sp. cf. T. inflata (Gabb), small form Locality Fie Gastropod Ampullina pseudoalveata (Packard) Pelecypods Crassatella gamma Popenoe Flaventia zeta Popenoe Glycymeris pacificus (Anderson) Lima beta Popenoe Liopistha anaana (Anderson) Pterotrigonia klamathonia (Anderson) Syncyclonema operculiformis (Gabb) Trigonarca californica Packard Locality F2 Gastropod Ampullina pseudoalveata (Packard) Pelecypods '"'Astarte'' sulcata Packard Calva regina Popenoe Trigonarca californica Packard Locality F3 Gastropod Cerithiid gastropod, probably n. sp. Cephalopod Otoscaphites aff. 0. inermis Anderson Locality F4 Gastropods Acteonella oviformis Gabb Anchura cf. A. condoniana Anderson GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA Locality F4-Continued Pelecypods Ambocardia delta (Popenoe) Crassatella gamma Popenoe Eriphyla ovoides (Packard) Glycymeris pacificus (Anderson) Lima beta Popenoe Lima? sp. B Pterotrigonia klamathonia (Anderson) Syncyclonema? sp. Locality F5 Gastropod Acteonella oviformis Gabb Pelecypod Trigonarca californica Packard Locality F6 Gastropod Anchura cf. A. condoniana Anderson Pelecypods Pinna sp. Syncyclonema operculiformis (Gabb) Trigonarca californica Packard Locality F7 Gastropods ''Alaria'' nodosa (Packard) Ampullina pseudoalveata (Packard) Anchura ef. A. condoniana Anderson? Cryptorhytis? sp. Tudicla? sp. Pelecypods "'Astarte'' sulcata Packard Calva regina Popenoe Camptonectes? sp. Crassatella gamma Popenoe Cucullaea gravida (Gabb)? Flaventia zeta Popenoe Glycymeris pacificus (Anderson) Gryphaea? n. sp. Inoceramus sp. A Inoperna bellarugosa Popenoe Lima beta Popenoe Liopistha anaana (Anderson) Pleuromya? sp. Pterotrigonia klamathonia (Anderson) ''Siphonalia' dubius Packard Syneyclonema operculiformis (Gabb) Trigonarca californica Packard Cephalopod Subprionocyclus cf. S. siskiyouensis (Anderson) Locality F8 Pelecypods Ambocardia (Isocardia) delta (Popenoe) Eriphyla ovoides (Packard) Lima beta Popencoe Locality F9 Gastropod Anchura cf. A. condoniana Anderson Pelecypods Calva regina Popenoe Clisocolus corrugatus Popenoe Lima beta Popencoe Pterotrigonia klamathonia (Anderson) Trigonarca californica Packard Locality F10 Pelecypods Cucullaea gravida (Gabb) GEOLOGY OF THE SANTA ANA MOUNTAINS D83 Locality F10-Continued Pterotrigonia klamathonia (Anderson) Spondylus? sp. B Locality F1 1 Gastropods Acteon politus (Gabb) Acteonella oviformis Gabb Ampullina pseudoalveata (Packard) Anchura cf. A. condoniana Anderson Pelecypods Acila n. sp. ''Aphrodina'' arata (Gabb) Corbula sp. A Flaventia zeta Popenoe Meekia sp. Parallelodon cf. P. brewerianus (Gabb) Pterotrigonia klamathonia (Anderson) Trigonarca californica Packard Cephalopod Baculites (Sciponoceras)fairbanksi Anderson Locality F12 Pelecypods Ostrea or Gryphaea sp. Trigonarca californica Packard Locality F13 Gastropods Anchura cf. A, condoniana Anderson Rostellinda dilleri? (White) Pelecypods Calva regina Popenoe Crassatella gamma Popenoe Cucullaea gravida (Gabb) Opis n. sp. B Pterotrigonia klamathonia (Anderson) Trigonarca californica Packard Locality F14 Gastropods Ampullina pseudoalveata (Packard) Anchura cf. A. condoniana Anderson Pelecypods Ambocardia delta (Popenoe) ''Aphrodina'' arata (Gabb) Calva regina Popenoe Clisocolus corrugatus Popenoe Corbula? sp. Crassatella gamma Popencoe Cucullaea gravida (Gabb) Eriphyla ovoides (Packard) Glycymeris pacificus (Anderson) Lima beta Popenoe Opis n. sp. B Pleuromya? sp. Pterotrigonia klamathonia (Anderson) ''Siphonalia'' dubius Packard Syncyclonema operculiformis (Gabb) Tenea sp. cf. T. inflata (Gabb), small form Trigonarca californica Packard Cephalopods Sciponoceras fairbanksi (Anderson) Subprionocyclus cf. S. siskiyouensis (Anderson) Locality F15 Pelecypods ''Aphrodina'' arata (Gabb) Crassatella gamma Popence Cucullaea gravida (Gabb) Glycymeris pacificus (Anderson) Locality F15-Continued Pterotrigonia klamathonia (Anderson) Locality F16 Gastropods Anchura cf. A. condoniana Anderson dubius Packard Pelecypods Ambocardia delta (Popenoe) ''Aphrodina'' arata (Gabb) Calva regina Popenoe Clisocolus corrugatus Popenoe Crassatella gamma Popencoe Cucullaea gravida (Gabb) Lima beta Popencoe Pterotrigonia klamathonia (Anderson) Syncyclonema operculiformis (Gabb) Tenea sp. cf. T. inflata (Gabb), small form Trigonarca californica Packard Trigonia oregana Packard Locality F17 Gastropods Anchura cf. A. condoniana Anderson Pyropsis sp. A *'Siphonalia'' dubius Packard Pelecypods Anomia? sp. Clisocolus corrugatus Popenoe Cucullaea gravida (Gabb) Glycymeris pacificus (Anderson) Lima cf. L. suciensis? Whiteaves Opis n. sp. B Pterotrigonia klamathonia (Anderson) Spondylus subnodosus (Packard) Trigonarca californica Packard Locality F18 Gastropods Ampullina pseudoalveata (Packard) Anchura cf. A. condoniana Anderson Pyropsis? sp. A Rostellinda dilleri? (White) Pelecypods Calva regina Popencoe Cucullaea gravida (Gabb) Glycymeris pacificus (Anderson) Lima? sp. B Opis n. sp. B Septifer? sp. Spondylus? sp. A Locality P19 =F19 Unlisted Late Cretaceous mollusks Locality F20 Unlisted Late Cretaceous mollusks HOLZ SHALE MEMBER Locality F21 Gastropod Anchura cf. A. condoniana Anderson? Pelecypods ''Aphrodina'' arata (Gabb) Cucullaea gravida (Gabb) Flaventia zeta Popenoe Glycymeris pacificus (Anderson) Lima beta Popenoe Liopistha hardingensis (Packard) D84 GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA Locality F21-Continued Pterotrigonia klamathonia (Anderson) Syncyclonema? sp. Cephalopod Baculites sp. Locality F21a Gastropod Ampullina pseudoalveata (Packard) Pelecypods Cyprimeria moore Popenoe Etea angulata (Packard)? Flaventia zeta Popencoe Glycymeris pacificus (Anderson) Trinacria cor Popenoe Locality F22 Pelecypods Cucullaea gravida (Gabb) Glycymeris pacificus (Anderson) Locality F23 Cephalopod Baculites sp. Locality F24 Pelecypods Crassatella n. sp. cf. C. lomana Cooper, long form f Glycymeris veatchii anae C. Smith Locality F24a Gastropods Lysis californiensis Packard Turritella chicoensis Gabb Pelecypods Cucullaea youngi Waring Eriphyla lapidis (Packard) Etea angulata (Packard) Glycymeris veatchii anae C. Smith Parallelodon cf. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) Locality F24b Gastropod Turritella chicoensis Gabb Pelecypods Eriphyla lapidis (Packard) Glycymeris veatchii anae C. Smith Opis n. sp. A Parallelodon cf. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) Locality F24c Gastropods Anchura ef. A. falciformis Gabb Biplica obliqua (Gabb) Gyrodes canadensis Whiteaves Tessarolax distorta? Gabb Turritella chicoensis Gabb Volutoderma santana Packard Pelecypods Crassatella cf. C. tuscana Gabb Cucullaea youngi Waring Eriphyla lapidis (Packard) Glycymeris veatchii anae C. Smith Parallelodon cf. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) Cephalopod Canadoceras cf. C. multisulecatum (Whiteaves) Locality F24d Gastropods Ampullina packardi Popenoe Locality F24d-Continued Biplica obliqua Gabb Euspira n. sp. ef. E. shumardiana (Gabb) Lysis californiensis Packard Perissitys brevirostris (Gabb) Turritella chicoensis Gabb Pelecypods Acila demessa Finlay Clisocolus cordatus Whiteaves Crassatella n. ef. C. lomana Cooper, long form Cucullaea youngi Waring Cymbophora angulata (Waring) Etea angulata (Packard) Flaventia lens (Gabb) Glycymeris veatchii (Gabb), giant form Glycymeris veatchii anae C. Smith Trinacria cor Popencoe Locality F25 Cephalopod Pachydiscus? sp. A Locality F26 Gastropods Ampullina packardi Popence Turritella chicoensis Gabb Volutoderma santana Packard Pelecypods Crassatella n. sp. ef. C. lomana Cooper, long form Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Tenea inflata (Gabb), large form Locality F27 Cephalopod Pachydiscus? sp. Locality F28 Pelecypod Acila demessa Finlay? Cephalopod Lytoceras? sp. Locality F29 Gastropods Biplica obliqua (Gabb) Turritella chicoensis Gabb Pelecypods Crassatella cf. C. tuscana Gabb Cucullaea youngi Waring Eriphyla ovoides (Packard) Glycymeris veatchii anae C. Smith? Opis n. sp. A Parallelodon cf. P. vancouverensis( Meek) Pterotrigonia evansana (Meek) Tenea inflata (Gabb), large form Cephalopod Baculites sp. Locality F30 Gastropods Anchura? sp. Turritella chicoensis Gabb Pelecypods Crassatella cf. C. tuscana Gabb Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith? Opis n. sp. A Parallelodon cf. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) GEOLOGY OF THE SANTA ANA MOUNTAINS D85 Locality F31 Gastropod Turritella chicoensis Gabb Pelecypods Calva bowersiana (Cooper)? Crassatella n. sp. cf. C. lomana Cooper, long form Cucullaea youngi Waring Flaventia lens (Gabb) Pterotrigonia evansana (Meek) Yaadia tryoniana (Gabb) Locality F32 Gastropods Biplica obliqua (Gabb) Euspira n. sp. cf. E. shumardiana (Gabb) Turritella chicoensis Gabb Pelecypods Meekia n. sp. A Pterotrigonia evansana (Meek) Locality F33 Gastropod Ampullina packardi Popenoe Pelecypods Etea angulata (Packard) Inoceramus cf. I. whitreyi (Gabb) Pterotrigonia evansana (Meek) Locality F34 Gastropod Turritella chicoensis Gabb Pelecypods Glycymeris veatchii anae C. Smith Parallelodon ef. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) Locality F34a Gastropods Euspira n. sp. cf. E. shumardiana (Gabb) Turritella chicoensis Gabb, typical form Volutoderma santana Packard Pelecypods Crassatella cf. C. tuscana Gabb Cucullaea youngi Waring Etea angulata (Packard) Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith Opis n. sp. A Parallelodon cf. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) Tenea inflata (Gabb), large form Locality F34b Gastropods Turritella chicoensis Gabb Volutoderma santana Packard Pelecypods Clisocolus cordatus Whiteaves Opis n. sp. A Parallelodon cf. P. vancouverensis(Meek) Locality F34c Gastropods Biplica obliqua (Gabb) Euspira n. sp. cf. E. shumardiana (Gabb) Lysis californiensis Packard Turritella chicoensis Gabb Volutoderma santana Packard Pelecypods Acila demessa Finlay Clisocolus cordatus Whiteaves Crassatella n. sp. cf. C. lomana Cooper, long form Locality F34c-Continued Cucullaea youngi Waring Cymbophora angulata (Waring) Cymbophora popenoei Saul Flaventia lens (Gabb) Glycymeris veatchii (Gabb), giant form Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Trinacria cor Popenoe Locality F34d Gastropods Euspira n. sp. cf. E. shumardiana (Gabb) Lysis californiensis Packard Perissitys brevirostris (Gabb) Volutoderma santana Packard Pelecypods Acila demessa Finlay Clisocolus cordatus Whiteaves Crassatella n. sp. cf. C. lomana Cooper, long form Cucullaea youngi Waring Cymbophora angulata (Waring) Flaventia lens (Gabb) Glycymeris veatchii (Gabb), giant form Glycymeris veatchii anae C. Smith Trinacria cor Popenoe Locality F35 Pelecypod Flaventia lens (Gabb) Locality F36 Gastropods Turritella chicoensis Gabb Volutoderma cf. V. averillii (Gabb) Pelecypods Calva bowersiana (Cooper) Crassatella n. sp. A Cucullaea youngi Waring Glycymeris veatchii anae C. Smith? Pterotrigonia evansana (Meek) ''Tellina'' cf. T. longa (Gabb) WILLIAMS FORMATION SCHULZ RANCH SANDSTONE MEMBER Locality F37 (Redeposited blocks of Baker Canyon Conglomerate in basal Schulz Ranch Sandstone) Gastropods Acteonella oviformis Gabb? Ampullina pseudoalveata (Packard) Potamides? sp. Pelecypods "Astarte"' sulcata Packard Glycymeris pacificus (Anderson)? Pteria n. sp. Trigonocallista regina (Popenoe) Locality F38 Gastropod Trajanella n. sp. Pelecypods Clisocolus cordatus Whiteaves Coralliochama n. sp. Crassatella n. sp. cf. C. lomana Cooper, long form Cucullaea youngi Waring Eriphyla lapidis (Packard) Etea angulata (Packard) Gervillia sp. Glycymeris veatchii (Gabb), giant form D86 - GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA Locality F38-Continued Opis n. sp. A Pachycardium coronaense (Packard) Pterotrigonia evansana (Meek) Septifer? sp. Spondylus subnodosus (Packard) Locality F39 Gastropod Margarites ornatissimus (Gabb) Pelecypods Acila demessa Finlay Calva bowersiana (Cooper) Coralliochama n. sp. Crassatella n. sp. cf. C. lomana Cooper, long form Cucullaea youngi (Waring) Eriphyla lapidis (Packard) Glycymeris veatchii (Gabb), giant form Opis n. sp. A Pachycardium coronaense (Packard) Pterotrigonia evansana (Meek) Locality F40 Gastropods Ampullina packardi Popenoe Epitonium? sp. Lysis californiensis Packard Turritella chicoensis Gabb Turritella ossa Popenoe Volutoderma santana Packard? Pelecypods Acila demessa Finlay Corbula? sp. Crassatella n. sp. ef. C. lomana Cooper, long form Glycymeris veatchii anae C. Smith Trinacria cor Popenoe Locality F41 Gastropods Ampullina packardi Popencoe Ampullina? n. sp. A Biplica obliqua (Gabb) Lysis californiensis Packard Turritella chicoensis Gabb Pelecypods Acila demessa Finlay Calva bowersiana (Cooper) Crassatella n. cf. C. lomana Cooper, long form Cymbophora angulata (Waring) Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Trinacria cor Popenoe Locality F42 Cephalopod Pachydiscus sp. Locality F43 Gastropods Lysis californiensis Packard Volutoderma santana Packard Pelecypods Crassatella cf. C. tuscana Gabb Eriphyla ovoides (Packard) Flaventia lens (Gabb) Pterotrigonia evansana (Meek) Trinacria cor Popenoe PLEASANTS SANDSTONE MEMBER Locality F44 Gastropods Ampullina packardi Popenoe Biplica obliqua (Gabb) Euspira n. sp. cf. E. shumardiana (Gabb) Gyrodes expansa canadensis Whiteaves Lysis californiensis Packard Perissitys brevirostris (Gabb) Turritella pescaderoensis Arnold Volutoderma magna Packard Pelecypods Anomia cf. A. lineata Gabb Calva bowersiana (Cooper) Camptonectes? n. sp. Clisocolus cordatus Whiteaves Crassatella n. sp. A Cucullaea youngi Waring Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith Ostrea sp. Pachycardium coronaense (Packard) Panope californica Packard Parallelodon cf. P. vancouverensis (Meek) Pinna sp. A Pterotrigonia evansana (Meek) Spondylus subnodosus (Packard) Tenea inflata (Gabb), large variety Yaadia tryoniana (Gabb) Cephalopods Baculites sp. Eutrephoceras sp. A Eutrephoceras sp. B Metaplacenticeras pacificum (J. P. Smith) f Pachydiscus? cf. P. peninsularis Anderson and Hanna Pachydiscus? sp. Locality F45 Gastropods Euspira n. sp. cf. E. shumardiana (Gabb) Turritella ossa Popenoe Turritella pescaderoensis Arnold Pelecypods Crassatella n. sp. ef. C. lomana Cooper, long form Glycymeris veatchii anae C. Smith Locality F46 Pelecypods Calva bowersiana (Cooper) Cymbophora popenoei Saul '"'Lutraria'' truncata? Gabb Locality F47 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F48 Gastropod Biplica obliqua (Gabb) Pelecypods Acila demessa Finlay Clisocolus cordatus Whiteaves Cymbophora popenoei Saul Locality F49 Gastropods Turritella pescaderoensis Arnold Volutoderma cf. V. averillii (Gabb) GEOLOGY OF THE SANTA ANA MOUNTAINS D87 Locality F49-Continued Pelecypods Crassatella n. sp. cf. C. lomana Cooper, long form Cucullaea youngi (Waring) Glycymeris veatchii anae C. Smith Cephalopods Nostoceras? aff. N. sternbergi Anderson and Hanna Locality F50 Pelecypods Acila demessa Finlay? Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves Cymbophora popenoei Saul Glycymeris veatchii anae C. Smith Legumen ooides (Gabb) Pterotrigonia evansana (Meek) Locality F51 Gastropods Biplica obliqua (Gabb) Turritella pescaderoensis Arnold Pelecypods Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves Cucullaea youngi Waring Cymbophora popenoei Saul Glycymeris veatchii anae C. Smith Pachycardium coronaense (Packard) Trinacria cor Popenoe Locality F52 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F53 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F54 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F55 Gastropod Volutoderma magna Packard Pelecypods Crassatella n. sp. cf. C. lomana Cooper, long form Parallelodon cf. P. vancouverensis(Meek) Cephalopod Metaplacenticeras pacificum (J. P. Smith)? Locality F56 Gastropod Turritella pescaderoensis Arnold Pelecypods Acila demessa Finlay Crassatella cf. C. tuscana Gabb Locality F57 Gastropod Biplica obliqua (Gabb) Pelecypods Clisocolus cordatus Whiteaves Cucullaea youngi Waring Cymbophora popenoei Saul Glycymeris veatchii anae C. Smith Inoceramus sp. A Parallelodon cf. P. vancouverensis(Meek) Pterotrigonia evansana (Meek) Locality F58 Pelecypods Calva bowersiana (Cooper)? Locality F58-Continued Clisocolus cordatus Whiteaves Cymbophora angulata (Waring) Flaventia lens (Gabb) Parallelodon cf. P. vancowerensis(Meek) Pterotrigonia evansana (Meek) Tenea inflata (Gabb), large form Locality F59 Gastropod Volutoderma magna Packard Locality F6O Gastropod Volutoderma? sp. Pelecypods Calva bowersiana (Cooper) Cymbophora popenoei Saul Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Cephalopod Metaplacenticeras californicum? (Anderson) Locality F61 Gastropod Biplica obliqua (Gabb) Pelecypods Cucullaea youngi Waring Cymbophora angulata (Waring) Pterotrigonia evansana (Meek) Locality F62 Gastropods Biplica obliqua (Gabb) Gyrodes canadensis Whiteaves Pelecypods Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves Cucullaea youngi Waring Cymbophora angulata (Waring) Cymbophora popenoei Saul Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Spondylus subnodosa (Packard) Cephalopods Metaplacenticeras pacificum (J. P. Smith) Puzosia ("Latidorsella") ef. P. ("L.") selwyniana Whiteaves ' Locality F63 Gastropod Volutoderma magna Packard Pelecypods Cucullaea youngi Waring Glycymeris veatchii (Gabb), giant form Locality F64 Pelecypods Clisocolus cordatus Whiteaves Crassatella cf. C. tuscana Gabb Cucullaea youngi Waring Cephalopod Pachydiscus? sp. B Locality F65 Cephalopod Puzosia ("'Latidorsella'") cf. P. ( "L.") selwyniana Whiteaves Locality F66 Pelecypod Spondylus subnodosus (Packard) D88 GEOLOGY OF THE EASTERN LOS ANGELES BASIN. SOUTHERN CALIFORNIA Locality F67 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F68 Pelecypods Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves? Cucullaea youngi Waring Cymbophora angulata (Waring) Locality F69 Gastropods Atira ornatissima (Gabb) Biplica obliqua (Gabb) Gyrodes canadensis Whiteaves Pelecypods Inoceramus sp. A Pinna sp. A Pterotrigonia evansana (Meek) Cephalopods Metaplacenticeras pacificum (J. P. Smith) Nostoceras? sp. A Puzosia ("'Latidorsella") ef. P. ("L.") selwyniana Whiteaves Locality F70 Gastropod Cerithium? suciaensis Packard Pelecypods Clisocolus cordatus Whiteaves Crassatella n. sp. A Glycymeris veatchii anae C. Smith Parallelodon cf. P. vancouverensis (Meek) Pterotrigonia evansana (Meek) Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F71 Gastropods Biplica obliqua (Gabb) Gyrodes canadensis Whiteaves Perissitys brevirostris (Gabb) Turritella pescaderoensis Arnold Pelecypods Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves Cucullaea? sp. Cymbophora angulata (Waring) Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Tenea inflata (Gabb), large form Trinacria cor Popenoe Locality F71a Gastropods '"'Fulgur'' hilgardi White Volutoderma ef. V. averillii (Gabb) Pelecypods Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves Cymbophora angulata (Waring) Cymbophora popenoei Saul Glycymeris veatchii (Gabb), giant form Glycymeris veatchii anae C. Smith Pterotrigonia evansana (Meek) Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F71b Gastropods Atira ornatissima (Gabb) Biplica obliqua (Gabb) '"'Fulgur' hilgardi White Gyrodes expansa canadensis Whiteaves Odostomia santana Packard Volutoderma cf. V. averillii (Gabb) Pelecypods Acila demessa Finlay Calva bowersiana (Cooper) Clisocolus cordatus Whiteaves Crassatella n. sp. A? Cymbophora angulata (Waring) Cymbophora popenoei Saul Flaventia lens (Gabb) Glycymeris veatchii anae C. Smith Legumen ooides (Gabb) Meekia sp. A Pterotrigonia evansana (Meek) Trinacria cor Popenoe Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F72 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F73 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F74 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F75 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F76 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F77 Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F78 Gastropod Volutoderma magna Packard Pelecypod Cucullaea youngi (Waring) Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F79 Cephalopod Baculites sp. Locality F80 Gastropods Turritella pescaderoensis Arnold Volutoderma magna Packard Pelecypod Clisocolus cordatus Whiteaves Cephalopods Metaplacenticeras pacificum (J. P. Smith) Pachydiscus ? sp. Locality F80a Cephalopod Metaplacenticeras pacificum (J. P. Smith) Locality F81 Pelecypods GEOLOGY OF THE SANTA ANA MOUNTAINS D89 Locality F81-Continued Locality F86-Continued Crassatella n. sp. A Glycymeris cf. G. veatchii major (Stanton) Glycymeris veatchii anae C. Smith? Macrocallista? sp. Panope californica Packard? Miltha (Plastomiltha?) n. sp.? Cephalopod Nuculana cf. N. gabbii (Gabb) Hamites? sp. Pitar? cf. P. uvasana (Conrad) Locality F82 Unidentified cardiid Gastropods Locality F87 Atira ornatissima (Gabb) Gastropods Biplica obliqua (Gabb) Cylichnina sp. Gyrodes expansa canadensis Whiteaves Turritella cf. T. pachecoensis Stanton Turritella pescaderoensis Arnold Pelecypods Pelecypods Corbicula? sp. Calva bowersiana (Cooper) Crassatella? sp. Lembulus? cf. L. striatula Forbes Locality F88 Pterotrigonia evansana (Meek) Gastropods Cephalopod Streptolathyrus? sp. Metaplacenticeras pacificum (J. P. Smith) Turritella pachecoensis Stanton, strongly noded form Pelecypods PALEOCENE Claibornites? cf. C. turneri (Stanton) SILVERADO FORMATION Glycymeris cf. G. veatchii major (Stanton) Pitar? cf. P. stantoni (Dickerson) Fossils identified by Ralph Steward, 1954, 1955, and Locality FAG Ellen J. Moore, 1959. (For locality descriptions and Gastropods U.S. Geological Survey locality numbers see megafossil Turritella cf. T. pachecoensis Stanton locality list.) Whitneyella? sp. Locality F83 Pelecypods _ f Gastropod Braghldontes cf. B. lqlwsonl (Nelson) Turritella pachecoensis Stanton, strongly noded form Tellfna C_f'_T' remondll.Gabb Locality F84 Unidentified nuculanid Gastropod Locality F90 Turritella cf. T. pachecoensis Stanton Gastropod Locality F85 Turritella pachecoensis Stanton, strongly noded form? Gastropods Pelecypod Brachysphingus? sp. Pitar? cf. P. uvasana (Conrad) Ficopsis sp. Locality F91 ''Turricula'' calafia Nelson Gastropod Turritella pachecoensis Stanton? Turritella pachecoensis Stanton? Pelecypods Locality F92 Crassatella n. sp. A Gastropods Cucullaea? cf. C. mathewsonii Gabb Polinices (Polinices)? cf. P. (P.) hornii Gabb Glycymeris cf. G. veatchii major (Stanton) a Turritella pachecoensis Stanton Locality F86 Pelecypods Gastropods Brachidontes sp. Amaurellina sp. Callista? (Costacallista?) ef. C. (C.) hornii (Gabb) Ancilla sp. Claibornites? turneri (Stanton) Calyptraea diegoana (Conrad) f Crassatella unioides (Stanton) Conus sp. Glycymeris cf. G. veatchii major (Stanton) Cylichnina cf. C. tantilla (Anderson and Hanna) Nuculana cf. N. gabbii (Gabb) Ectinochilus (Cowlitzia) sp. Locality F93 Ficopsis sp. Gastropods Homalopoma? cf. H. wattsi (Dickerson) Polinices (Polinices) cf. P. (P.) hornii Gabb Polinices (Polinices)? ef. P. (P.) horni Gabb Turritella pachecoensis Stanton, strongly noded form Pseudoliva? sp. Pelecypods Pseudoperissolax sp. Callista? (Costacallista?) ef. C. (C.) hornii (Gabb) Scaphander (Mirascapha) costatus (Gabb) Crassatella unioides (Stanton) Turritella pachecoensis Stanton? Cucullaea? cf. C. mathewsonii Gabb Turritella pachecoensis Stanton, strongly noded form Locality F94 Pelecypods 'Gastropod Brachidontes cf. B. lawsoni (Nelson) Turritella pachecoensis Stanton, strongly noded form? Corbula cf. C. tomulata M. A. Hanna Pelecypods Cucullaea? cf. C. mathewsonii Gabb Crassatella sp. Ostrea sp. D90 Locality F95 Gastropods Turritella pachecoensis Stanton? Turritella pachecoensis Stanton, strongly noded form Unidentified naticid Pelecypods Cucullaea? cf. C. mathewsonii Gabb Pitar? cf. P. stantoni (Dickerson) Locality F96 (identified by J. G. Vedder) Gastropods Polinices (Polinices)? cf. P. (P.) hornii Gabb Turritella cf. T. pachecoensis Stanton Pelecypods Brachidontes sp. Callista (Costacallista) ef. C. (C.) hornii (Gabb) Calorhadia? sp. Claibornites? cf. C. turneri (Stanton) Glycymeris cf. G. veatchii major (Stanton) Pitar cf. P. stantoni (Dickerson) Locality F97 Pelecypods Mytilus? sp. Polymesoda? sp. Locality F98 Pelecypod Ostrea sp. Locality F99 Gastropod Goniobasis? sp. Pelecypods Mytilus sp. Polymesoda cf. P. tenuis (Gabb) EOCENE SANTIAGO FORMATION Fossils identified by Ralph Stewart, 1954, 1955, and Ellen J. Moore, 1959, with nomenclatural alterations by C. R. Givens, 1977. (For locality descriptions and U.S. Geological Survey locality numbers see megafossil locality list.) Locality F99a Gastropods Cylichnina? ef. C. tantilla (Anderson and Hanna) Turritella sp. Pelecypods Acanthocardia?(Schedocardia?) cf. A. (8) brewerii (Gabb) Brachidontes? cf. B. cowlitzensis (Weaver and Palmer) Pitar? sp. Tellina cf. T. soledadensis M. A. Hanna Locality F99b (identified by J. G. Vedder) Gastropod Turritella uvasana Conrad, subsp.? cf. T. uvasana applinae Hanna Locality F100 Gastropods Bittium cf. B. alternatum (Gabb) Conus cf. C. remondii Gabb Ectinochilus (Cowlitzia) cf. E. (C.) supraplicatus (Gabb) Ficopsis cooperiana Stewart GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Locality F100-Continued Ficopsis remondii crescentensis Weaver and Palmer Fusimitra? cf. F. simplicissima (Cooper) Lyrosurcula? n. sp.? Pseudoperissolax sp. cf. P. blakei praeblakei (Vokes) Protosurcula? sp. Scaphander (Mirascapha) cf. S. (M.) costatus (Gabb) Turritella uvasana Conrad, subsp.? cf.T. uvasana applinae Hanna Pelecypods Brachidontes cf. B. cowlitzensis (Weaver and Palmer) Nemocardium linteum (Conrad) Ostrea sp. Pitar? sp. Thracia cf. T. sorrentoensis M. A. Hanna Venericardia (Pacificor) cf. V. (P.) hornii (Gabb) Locality F101 Gastropods Pachycrommium? cf. P .clarki Stewart Pseudoperissolax? sp. Pelecypod Unidentified lucinid? Locality F102 (identified by J. G. Vedder) Gastropods Bittium alternatum (Gabb) Bonnellitia cf. B. paucivaricata (Gabb) Calyptraea diegoana (Conrad) Conus remondii Gabb Cylichnina cf. C. tantilla (Anderson and Hanna) Ectinochilus (Cowlitzia) ef. E. (C.) supraplicatus (Gabb) Eocernina cf. E. hannibali (Dickerson)? Euspira nuciformis (Gabb) Ficopsis remondii crescentensis Weaver and Palmer Galeodea sp. Perse sinuata (Gabb) Pleurofusia? sp. Pseudoperissolax blakei (Conrad) Turritella buwaldana Dickerson Pelecypods Corbula sp. Glycymeris cf. G.sagittata (Gabb)? Miltha sp. Pitar (Calpitaria) ef. P. (C.) uvasanus (Conrad) Venericardia (Venericor) sp.? Locality F103 Gastropod Turritella cf. T. buwaldana Dickerson Pelecypod Venericardia sp. Locality F104 Gastropods Ancilla ef. A. gabbi (Cossman) Ectinochilus (Cowlitzia) ef. T. (C.) supraplicatus (Gabb) Ficopsis remondii crescentensis Weaver and Palmer Molopophorus antiquatus (Gabb) Pachycrommium clarki Stewart Scaphander (Mirascapha) costatus (Gabb) Sinum obliquum (Gabb) Tejonia cf. T. lajollaensis (Stewart) Turritella cf. T. buwaldana Dickerson Pelecypods Acanthocardia (Schedocardia?) cf. A. (8) brewerii (Gabb) Brachidontes cf. B. cowlitzensis (Weaver and Palmer) GEOLOGY OF THE SANTA ANA MOUNTAINS Locality F104-Continued Eomiltha? sp. Venericardia sp. Locality F105 Gastropods Conus cf. C. remondii Gabb Ectinochilus (Cowlitzia) ef. E. (C.) supraplicatus (Gabb) Scaphander (Mirascapha) cf. S. (M.) costatus (Gabb) Pelecypod Unidentified tellinid? Locality F106 Gastropod Galeodea n. sp. aff. G. petersoni (Conrad) Pelecypods Acanthocardia (Schedocardia) brewerii (Gabb) Callista? (Costacallista?) ef. C. (C.) hornii (Gabb) Nemocardium linteum (Conrad) Pitar (Calpitaria) ef. P. (C.) uvasanus (Conrad) Tellina? aff. T. cowlitzensis Weaver Venericardia (Venericor) sp. Locality F107 Gastropods Bittium cf. B.? alternata (Gabb) Calyptraea diegoana (Conrad) Conus cf. C. remondii Gabb Crepidula (Spirocrypta) cf. C. (S.) pileum (Gabb) Crommium? sp. Cylichnina? cf. C. tantilla (Anderson and Hanna) Ectinochilus (Cowlitzia) ef. E. (C.) supraplicatus (Gabb) Euspira cf. E. nuciformis (Gabb) Euspirocrommium? sp. Ficopsis remondii crescentensis Weaver and Palmer Galeodea sp. Megistostoma? cf. M. gabbiana (Stolicka) Molopophorus? cf. M. antiquatus (Gabb) Pachycrommium clarki (Stewart) Scaphander (Mirascapha) cf. S. (M.) costatus (Gabb) Tejonia cf. T. lajollaensis (Stewart) Turritella cf. T. buwaldana Dickerson Turritella uvasana Conrad, subsp.? cf. T. uvasana applinae Hanna Unidentified turrid Pelecypods Corbula cf. C. parilis Gabb Corbula n. sp.? Crassatella cf. C. uvasana Conrad Glycymeris cf. G. sagittata (Gabb) Ostrea sp. Pitar? sp. Unidentified cardiid? Venericardia (Pacificor) ef. V. (P.) hornii (Gabb) Locality F108 Gastropods Agaronia? cf. A.? mathewsonii Gabb Ancilla? sp. Conus cf. C. remondii Gabb Cylichnina? sp. Ectinochilus (Cowlitzia) supraplicatus (Gabb) Euspirocrommium? sp. Galeodea? sp. Neverita? sp. Perse? n. sp. Pleurofusia? cf. P. fresnoensis (Arnold) D91 Locality F108-Continued Pseudoliva cf. P. inornata Dickerson Scaphander (Mirascapha) costatus (Gabb) Tejonia cf. T. lajollaensis (Stewart) Turritella cf. T. buwaldana Dickerson Xenophora? cf. X. stocki Dickerson Pelecypods Acanthocardia (Schedocardia?) sp. Glycymeris? sp. ''Nuculana"' ef. "N." gabbii (Gabb) Pitar? (Calpitaria?) ef. P. (C.) uvasana (Conrad) Locality F109 Gastropods Calyptraea cf. C. diegoana (Conrad) Coalingodea tuberculiformis (Hanna) Conus cf. C. remondii Gabb Ficopsis remondii crescentensis Weaver and Palmer Pseudoperissolax cf. P. blakei praeblakei (Vokes) Tejonia cf. T. lajollaensis (Stewart) Turritella cf. T. buwaldana Dickerson Pelecypods Acanthocardia? (Schedocardia?) sp. Brachidontes cf. B. cowlitzensis (Weaver and Palmer) Corbula sp. Nemocardium cf. N. linteum (Conrad) Pitar? (Calpitaria?) ef. P. (C.) campi Vokes Tellina cf. T. soledadensis M. A. Hanna Locality F110 Gastropod Molopophorus? cf. M. antiquatus (Gabb) Pelecypods Acanthocardia? (Schedocardia?) cf. A. S. brewerii (Gabb) Corbula cf. C. parilis Gabb Pitar? (Calpitaria?) cf. P. (C.) campi Vokes Locality F111 Pelecypod Ostrea sp. Locality F112 (identified by J. G. Vedder) Gastropods Cylichnina? sp. Ranellina? sp. Turritella buwaldana Dickerson Pelecypods Acanthocardia (Schedocardia) brewerii (Gabb)? Pitar? sp. ?Spisula merriami Packard Volsella? sp. Locality F113 (identified by J. G. Vedder) Gastropods Bittium alternatum (Gabb) Calyptraea diegoana (Conrad) Conus remondii Gabb Cylichnina cf. C. tantilla (Anderson and Hanna) Ectinochilus (Cowlitzia) cf. E. (C.) supraplicatus (Gabb) Ficopsis cf. F. remondii crescentensis Weaver and Palmer Molopophorus antiquatus (Gabb) Niso polita Gabb Olivella cf. O0. mathewsonii Gabb ?Perse sinuata (Gabb) Pleurofusia? sp. Pseudoperissolax blakei (Conrad) D92 Locality F113-Continued Scaphander costatus (Gabb) Tejonia lajollaensis (Stewart) Turritella aff. T. buwaldana Dickerson Pelecypods Brachidontes sp. Corbula sp. Glycymeris cf. G.sagittata (Gabb)? Pitar? (Calpitaria?) cf. P. (C.) uvasana (Conrad) Locality F114 (identified by W. P. Woodring, as published in U. S. Geological Survey Preliminary Chart 12 (Woodring and Popenoe, 1945) with nomenclatural alterations by C. R. Givens, 1977) Gastropods Calyptraea diegoana (Conrad) Loxotrema cf. L. turritum Gabb Pachycrommium cf. P. clarki (Stewart) Scaphander costatus (Gabb) Tejonia lajollaensis (Stewart) Turritella buwaldana Dickerson? Pelecypods Acanthocardia (Schedocardia) brewerii (Gabb) Callista (Costacallista)? ef. C. (C.) hornii (Gabb) Glycymeris cf. G. sagittata (Gabb)? Nemocardium linteum (Conrad) Pitar? (Calpitaria) cf. P. (C.) uvasana (Conrad) Locality F114a Pelecypods j Mytilus cf. M. dichotomus Cooper Pododesmus (Monia) cf. P. (M.) inornatus (Gabb) Locality F114b Gastropods Calyptraea cf. C. diegoana (Conrad) Turritella cf. T. meganosensis Clark and Woodford Pelecypods Acanthocardia? (Schedocardia?) cf. A. (S.) brewerii (Gabb) Brachidontes cf. B. cowlitzensis (Weaver and Palmer) Corbula cf. C. parilis Gabb Nemocardium? sp. Pitar? (Calpitaria?) ef. P. (C.) campi Vokes Spisula? sp. Tellina cf. T. soledadensis M. A. Hanna EOCENE(?) TO MIOCENE SESPE AND VAQUEROS FORMATIONS, UNDIFFERENTIATED Fossils identified by J. G. Vedder and W. P. Wood- ring, 1953, with nomenclatural alterations by Ellen J. Moore, 1977. (For locality descriptions and U. S. Geological Survey locality numbers see megafossil loc- ality list.) Locality F115 Gastropod Ocenebra wilkesana (Anderson) Cirriped Balanus sp. GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Locality F116 Echinoid Kewia? cf. K. fairbanksi (Arnold) Gastropods Neverita (Glossaulax) reclusiana (Deshayes)? Olivella (Callianax?) santana Loel and Corey ''Terebra'' santana Loel and Corey Pelecypods Anadara (Larkinia) santana (Loel and Corey) Tivela (Pachydesma) inezana (Conrad) Locality F117 Gastropods Calyptraea (Trochita) filosa (Gabb)? Ocenebra topangensis Arnold Pelecypods Crenomytilus cf. C. expansus (Arnold) Zirface cf. Z. dentata (Gabb) Cirriped Balanus sp. Locality F118 Echinoid V aquerosella ef. V. norrisi (Pack) Locality F119 Gastropods Ocenebra topangensis Arnold Trophon (Austrotrophon) cf. T. (A.) kernensis Anderson Pelecypods Crenomptilus cf. C. expansus (Arnold) Lyropecten magnolia (Conrad) Solen sp.? Cirripeds Balanus sp. Tamiosoma sp. Locality F120 Pelecypods Crassatella cf. C. granti (Wiedey) Miltha (Miltha) sanctaecrucis (Arnold) Locality F121 Gastropods Bittium topangensis (Arnold)? Conus (Chelyconus) owenianus Anderson Megasurcula cf. M. keepi (Arnold) Neverita (Glossaulax) reclusiana (Deshayes)? Pelecypod Macoma (Rexithaerus) secta (Conrad)? Cirriped Balanus sp. Locality F122 Gastropods Calyptraea (Trochita) filosa (Gabb)? Ocenebra topangensis Arnold ''Terebra'' santana Loel and Corey Turritella (Torcula) inezana santana Loel and Corey Pelecypods Anadara (Larkinia) santana (Loel and Corey)? Corbula sp. Crenompytilus ef. C. expansus (Arnold) Dosinia margaritana Wiedey Saccella sp.? Saxidomus aff. S. vaquerosensis Arnold)? Tivela (Pachydesma) inezana (Conrad) Cirriped Balanus sp. Locality F123 Echinoid Kewia? fairbanksi santanensis (Kew) GEOLOGY OF THE SANTA ANA MOUNTAINS Locality F124 Gastropods Olivella (Callianax?) santana Loel and Corey Potamides sespeensis Loel and Corey? Rapana cf. R. vaquerosensis (Arnold) Rapana vaquerosensis imperialis Hertlein and Jordan ''Terebra'' santana Loel and Corey Turritella (Torcula) inezana santana Loel and Corey Pelecypod Anadara (Larkinia) santana (Loel and Corey) Cirriped Balanus sp. Locality F125 Gastropods Rapana aff. R. vaquerosensis imperialis Hertlein and Jordan Turritella (Torcula) inezana santana Loel and Corey Pelecypods Anadara (Larkinia) santana (Loel and Corey) Clementia (Egesta) pertenius (Loel and Corey) Locality F126 Echinoid Kewia? cf. K. ? fairbanksi (Arnold) Gastropod '"'Terebra" cf. ""T.' santana Loel and Corey Pelecypod Macoma? sp. Locality F127 Echinoid V aquerosella? vaquerosensis (Kew)? Gastropod Calyptraea (Trochita) filosa (Gabb)? Pelecypod Tellina (Olcesia) cf. T. (O.) piercei (Arnold) Locality F128 Gastropod Turritella (Torcula) inezana santana Loel and Corey Locality F129 Echinoid Kewia? cf. K.? fairbanksi (Arnold) Gastropod '"'Terebra'" cf. "T." santana Loel and Corey Pelecypod Macoma? sp. Locality F130 Pelecypods Anadara (Larkinia) santana (Loel and Corey) Clementia (Egesta) cf. C. (E.) pertenuis (Gabb) Macoma? sp. Locality F131 Gastropod Conus (Chelyconus) owenianus Anderson Pelecypod Crassatella cf. C. granti (Wiedey) Locality F132 Gastropod Turritella (Torcula) inezana santana Loel and Corey Pelecypods Ostrea sp. Tellina (Tellinella) idae Dall? Tivela (Pachydesma) inezana (Conrad) Locality F133 Gastropods ''Terebra'' santana Loel and Corey Turritella inezana santana Loel and Carey Pelecypods D93 Locality F133-Continued Ostrea sp. Tellina? sp. Tivela (Pachydesma) cf. T.(P.) inezana (Conrad) Locality F134 Echinoid Kewia? fairbanksi santanensis (Kew) Pelecypods Crassostrea cf. C. eldridgei (Arnold) Ostrea sp. Locality F135 Gastropods Conus (Chelyconus) owenianus Anderson Neverita (Glossaulax) reclusiana (Deshayes)? Olivella (Callianax?) santana Loel and Corey Rapana cf. R. vaquerosensis imperialis Hertlein and Jor- dan ~ Pelecypod Tivela (Pachydesma) inezana (Conrad) Cirriped Balanus sp. Locality F136 Gastropod Turritella (Torcula) inezana santana Loel and Corey Locality F137 Gastropod Turritella (Torcula) cf. T. (T.) inezana santana Loel and Corey Pelecypod Ostrea sp. Locality F138 Gastropods Rapana cf. R. vaquerosensis (Arnold)? Turritella (Torcula) inezana santana Loel and Corey Pelecypods Anadara (Larkinia) cf. A. (L.) santana (Loel and Corey) Here excavata (Carpenter)? Locality F139 Gastropod Rapana vaquerosensis imperialis Hertlein and Jordan Locality F140 Pelecypod Lyropecten cf. L. miguelensis (Arnold) Locality V1 Elasmobranchs ?0xyrhina sp. Batoid, gen. and sp. indet. Chelonian Gen. and sp. indet. Equid Miohippus, Parahippus, or Anchitherium Camelid Paratylopus cf. P. primaevus Matthew MIOCENE TOPANGA FORMATION Fossils identified by J. G. Vedder and W. P. Wood- ring, 1953, with nomenclatural alterations by Ellen J. Moore, 1977. (For locality descriptions and U. S. Geological Survey locality numbers see megafossil loc- ality list.) D94 Locality F141 Pelecypods Chione (Chionopsis) temblorensis (Anderson)? Dosinia (Dosinia) whitreyi (Gabb) Lyropecten crassicardo (Conrad)? Locality F142 Gastropods Bittium topangensis (Arnold) Calyptraea (Trochita) filosa (Gabb)? Mitrella sp. Turritella ocoyana Conrad T. temblorensis Wiedey Pelecypods Cryptomya? sp. Leptopecten andersoni (Arnold) Locality F143 Gastropod Bittium tonpangensis (Arnold)? Pelecypod Leptopecten andersoni (Arnold)? Locality F144 Echinoid V aquerosella norrisi (Pack) Pelecypod Crenomytilus cf. C. expansus (Arnold)? Locality F145 Gastropods Calyptraea (Trochita) filosa (Gabb)? Turritella ocoyana Conrad Turritella cf. T. ocoyana topangensis Merriam Turritella temblorensis Wiedey Pelecypod Chione (Chionopsis) temblorensis (Anderson)? Cirriped Balanus sp. Locality F146 Echinoid V aquerosella norrisi (Pack) Locality F147 Gastropods Acmaea? sp. Calyptraea (Trochita) filosa (Gabb)? Ficus (Trophosycon) cf. F. (T.) kerniana (Cooper) Neverita (Glossaulax) reclusiana (Deshayes)? Ocenebra topangensis Arnold Trophon (Austrotrophon) cf. T. (A.) kernensis Anderson? Turritella cf. T. ocoyana topangensis Merriam Pelecypods Anadara (Anadara) cf. A. (A.) osmonti (Dall) Anomia? sp. Chione (Chionopsis) cf. C. (C.) temblorensis (Anderson) Hiatella? sp. Miltha (Miltha) sanctaecrucis (Arnold)? Panopea cf. P. generosa (Gould) Tellina (Tellinella) idae Dall? Vertipecten nevadanus (Conrad) Locality F148 Pelecypod Vertipecten nevadanus (Conrad) Locality F149 Pelecypod Vertipecten nevadanus (Conrad) Locality F150 Gastropods GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Locality F150-Continued Neverita (Glossaulax) reclusiana (Deshayes)? Ocenebra topangensis Arnold Turritella ocoyana Conrad Pelecypods Crassotrea eldridgei ynezana (Loel and Corey)? Crassotrea cf. C. titan subtitan Loel and Corey Vertipecten nevadanus (Conrad) Locality F151 Gastropod Turritella ocoyana Conrad Pelecypod Crassotrea cf. C. titan subtitan Loel and Corey Locality F152 Echinoid V aquerosella norrisi (Pack) Locality F153 Echinoids V aquerosella andersoni (Twitchell) Spatangoid Locality F154 Gastropods Turritella ocoyana Conrad Turritella cf. T. ocoyana topangensis Merriam Locality F155 Gastropods Cancellaria (Euclia) cf. C. (E.) condoni Anderson Neverita (Glossaulax) reclusiana (Deshayes)? Oliva (Oliva) californica Anderson Tritonalia? sp. Turritella ocoyana Conrad Turritella cf. T. ocoyana topangensis Merriam Turritella temblorensis Wiedey Pelecypod Corbula sp. Cirriped Balanus sp. Locality F156 Gastropods Bruclarkia cf. B. barkeriana (Cooper) Calyptraea (Trochita) filosa (Gabb)? Trophon (Austrotrophon) cf. T. (A.) kernensis Anderson Pelecypods Amiantis cf. A. callosa (Conrad)? Chione (Chionopsis) temblorensis (Anderson) Dosinia cf. D. margaritana Wiedey Spisula cf. S. catilliformis Conrad Tellina (Olcesia) cf. T. (O.) piercei (Arnold) Tresus sp. Locality F157 Pelecypod Vertipecten nevadanus (Conrad) Locality F158 Gastropod Bruclarkia cf. B. barkeriana (Cooper) Pelecypods Chione (Chionopsis) cf. C. (C.) temblorensis (Anderson) Clementia (Egesta) cf. C. (E.) pertenuis (Gabb) Dosinia cf. D. margaritana Wiedey Here cf. H. excavata Carpenter Macrocallista aff. M. squalida (Sowerby) Panopea cf. P. generosa (Gould) Spisula sp.? Locality F159 Gastropod GEOLOGY OF THE SANTA ANA MOUNTAINS Locality F159 -Continued Nassarius (Catilon?) ef. N. (C.?) antiselli (Anderson and Martin) Pelecypods Anadara (Anadara) ef. A. (A.) osmonti (Dall) Cyclocardia? sp. Lucinoma cf. L. annulata (Reeve)? Saccella sp. Locality F160 Gastropod Turritella ocoyana Conrad Locality F161 Gastropod Turritella ocoyana Conrad Pelecypods Chione (Chionopsis) temblorensis (Anderson) Locality F162 Gastropods ''Cancellaria'' n. sp.? A Conus (Chelyconus) owenianus Anderson Ficus (Trophosycon) cf. F. (T.) kerniana (Cooper) Neverita (Glossaulax) reclusiana (Deshayes)? Turritella ocoyana Conrad Pelecypods Chione (Chionopsis) temblorensis (Anderson)? Dosinia cf. D. margaritana Wiedey Locality F163 Gastropods Amphissa sp. Antillophos posunculensis (Anderson and Martin) Bittium topangensis (Arnold) Bittium topangensis (Arnold), form lacking prominent nodes Cancellaria (Euclia) cf. C. (E.) cassidiformis Sowerby Cancellaria (Euclia) ef. C. (E.) condoni (Anderson) Cancellaria (Pyruclia) C. (P.) lickana Anderson and Martin ''Cancellaria'' n. sp. ? A ''Cancellaria'' n. sp. ? B Conus (Chelyconus) owenianus Anderson Conus (Lithoconus) ef. C. (L.) hayesi Arnold Conus (Lithoconus) cf. C. (L.) regularis Sowerby Crucibulm aff. C. spinosum (Sowerby) Mitrella (Columbellopsis) aff. M. (C.) tuberosa (Car- penter) Murex (Chicoreus) n. sp.? Nassarius n. sp.? Nassarius (Catilon?) cf. N. (C.?) antiselli (Anderson and Martin) Neverita (Glossaulax) reclusiana (Deshayes) Neverita (Glossaulax) reclusiana (Deshayes), low spired form Ocenebra wilkesana (Anderson) Oliva (Oliva) californica Anderson Sinium scopulosum (Conrad) Strombina carlosensis Durham? Tegula sp. Terebra (Terebra) cooperi (Anderson) Thais (Thaisella) cf. T. (T.) edmondi Arnold Tritonalia n. sp.? Trochita trochiformis (Born) Turricula cf. T. maculosa (Sowerby) Turricula ef. T. ochsneri (Anderson and Martin) Turricula cf. T. wilsoni (Anderson and Martin) Turricula? sp. D95 Locality F163-Continued Turritella ocoyana Conrad Turritella cf. T. ocoyana topangensis Merriam Turritella temblorensis Wiedey Pelecypods Amiantis cf. A. callosa (Conrad) Amiantis n. sp.? Anadara (Anadara) ef. A. (A.) osmonti (Dall) Anadara (Cunearca) cf. A. (C.) rivulata (Wiedey) Anodontia (Pegophysema) cf. A. (P.) edentuloides (Ver- rill) Chione (Chionopsis) temblorensis (Anderson) Chlamys cf. C. hertleini (Loel and Corey) Clementia (Egesta) pertenuis (Gabb) Corbula (Caryocorbula) cf. C. (C.) luteola Cooper Crassotrea freudenbergi Hertlein and Jordan? Crassotrea cf. C. titan subtitan Loel and Corey Crenomptilus cf. C. expansus Arnold Eucrassatella n. sp.? Fellaniella cf. F. harfordi (Anderson) Glycymeris (Glycymeris) aff. G. (Broderip) Glycymeris cf. G. whaleyi Nicol Here excavata Carpenter Leptopecten andersoni (Arnold)? Lucinoma cf. L. annulata (Reeve) Macrocallista (Megapitaria) aff. M. (M.) squalida (Sow- erby) Miltha (Miltha) sanctaecrucis (Arnold) Ostrea sp. Psammotreta obesa (Deshayes) Saxidomus aff. S. vaquerosensis Arnold Semele? sp. Spisula cf. S. catilliformis Conrad? Tagelus cf. T. clarki Loel and Corey Tellina (Olcesia) cf. T. (O.) piercei (Arnold) Tellina (Tellinella) idae Dall Tivela (Tivela) cf. T. (T.) delesserti Deshayes Trachycardium (Dallocardia) senticosum (Sowerby) Trachycardium cf. T. vaquerosensis (Arnold) Cirripeds Balanus sp. Balanus sp,. heavy ribbed form Locality F164 Gastropod Turritella ocoyana Conrad Pelecypod Leptopecten andersoni (Arnold) Locality F165 Pelecypod Leptopecten andersoni (Arnold) Locality F166 Gastropod Turritella cf. T. ocoyana Conrad Pelecypods Leptopecten andersoni (Arnold) Trachycardium (Acrosterigma) cf. T. (A.) vaquerosensis (Arnold) (G.) maculata Locality F167 Gastropods Bruclarkia cf. B. barkeriana (Cooper)? Calyptraea (Calyptraea) inornata (Gabb) Neverita (Glossaulax) reclusiana (Deshayes)? Pelecypods Chione (Chionopsis) temblorensis (Anderson) Dosinia margaritana Gabb D96 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Locality F167-Continued Locality F173-Continued Gari edentula (Gabb)? Tellina (Olcesia) ef. T. (O.) piercei (Arnold)? Leptopecten andersoni (Arnold) Tellina (Tellinella) idae Dall? Panopea cf. P. generosa (Gould) Trachycardium (Dallocardia) cf. T. (D.) quadrigenarium> Saxidomus aff. S. vaquerosensis Arnold (Conrad) Spisula sp. ? Trachycardium (Acrosterigma) cf. T. (A.) vaquerosensis Trachycardium (Acrosterigma) cf. T. (A.) vaquerosensis (Arnold) j (Arnold) PLIOCENE becellt OS FERNANDO MEMBER Pelecypod Leptopecten cf. L. discus (Conrad) Fossils identified by W. P. Woodring and Ellen J. Locality F169 Moore, 1952, with nomenclature alterations by Ellen J. GaStr°¥°d§ Moore, 1977. (For locality descriptions and U.S. urritella ocoyana Conrad & 3 a s Turrielin of. I. oonvanudopangensis Méetviain Geological Survey numbers see megafossil locality list.) Turritella temblorensis Wiedey Pelecypod Locallty F174 Ostrea sp. Gastropods Locality F170 Barbarofusus cf. B. arnoldi (Cossmann) Gastropods Crepidula sp. Megathura sp. Megasurcula sp. Trophon (Austrotrophon) cf. T. (A.) kernensis Anderson? Nassarius sp. Turritella cf. T. ocoyana Conrad Neverita (Glossaulax) reclusiana (Deshayes)? Pelecypods Pelecypods Tellina (Olcesia) cf. T. (O.) piercei (Arnold) Acila (Truncacila) castrensis (Hinds) Trachycardium (Acrosterigma) cf. T. (A.) vaquerosensis Anadara (Anadara) trilineata (Conrad)? (Arnold) Chione? sp. Cirriped Lucinoma cf. L. annulata (Reeve) Balanus sp. Saccella taphria (Dall) Locality F171 Tellina? sp. Pelecypod Locality F175 Amusium lompocensis (Arnold) Gastropods Locality F172 Astraea (Megastrea) cf. A. (M.) gradata (Grant and Gastropod Gale), operculum Turritella cf. T. ocoyana Conrad Neverita (Glossaulax) reclusiana (Deshayes)? Pelecypods Pelecypods Amusium lompocensis (Arnold) Amiantis callosa (Conrad)? Clementia (Egesta) pertenuis (Gabb) Diplodonta cf. D. subquadrata Carpenter Crassotrea cf. C. titan subtitan Loel and Corey Miltha? sp. Lyropecten crassicardo (Conrad) Cirriped Trachycardium (Acrosterigma) cf. T. (A.) vaquerosensis Balanus? sp. (Arnold) Locality F176 Cirriped Gastropods Balanus sp. Crepidula? sp. Locality F173 Turritella gonostoma hemphilli Merriam? Gastropods Pelecypods Antillophos posunculensis (Anderson and Martin) Anadara (Anadara) trilineata calcarea (Grant and Gale) Cancellaria (Euclia) ef. C. (E.) condoni Anderson Cyclocardia sp. Ficus (Trophosycon) cf. F. (T.) kerniana (Cooper) Macoma? sp. Fissurella rixfordi Hertlein Thyasira cf. T. gouldii (Philippi) Neverita (Glossaulax) reclusiana (Deshayes)? Locality F177 Sinium scopulosum (Conrad) Gastropods Turritella ocoyana Conrad Astraea (Megastrea) cf. A. (M.) gradata (Grant and Pelecypods Gale), operculum Amusium cf. A. lompocensis (Arnold) Neverita (Glossaulax) reclusiana (Deshayes)? Chione (Chionopsis) temblorensis (Anderson) Turritella gonostoma hemphilli Merriam Clementia (Egesta) pertenuis (Gabb) Pelecypod Crenomytilus ef. C. expansus Arnold? Anadara (Larkinia) camuloensis (Osmont) Leptopecten andersoni (Arnold) Locality F178 Macrocallista (Megapitaria) aff. M. (M.) squalida (Sow- Gastropods erby) § Neverita (Glossaulax) reclusiana (Deshayes)? Miltha (Miltha) sanctaecrucis (Arnold) Turritella gonostoma hemphilli Merriam? Panopea cf. P. generosa (Gould) Pelecypod Solen sp. Anadara (Anadara) trilineata calcarea (Grant and Gale) GEOLOGY OF THE SANTA ANA MOUNTAINS LIST OF MICROFOSSILS MIOCENE TOPANGA FORMATION Fossils identified by Patsy B. Smith, 1958, and pub- Locality m184-Continued V alvulineria californica obesa Cushman V alvulineria cf. V. grandis Cushman and Galliher V alvulineria williami Kleinpell Virgulina californiensis Cushman lished in 1960. (R, rare; F, few; C, common; A, @aDUN~ | Locality m185 dant.) (For locality descriptions and U. S. Geological Survey locality numbers see microfossil locality list.) Locality m179 Bolivina advena Cushman, undescribed variant Buliminella curta Cushman Buliminella subfusiformis Cushman Nonion costiferum (Cushman) Nonion aff. N. costiferum (Cushman) Locality m180 Bolivina advena Cushman var. Nonion aff. N. costiferum (Cushman) Locality m181 Bolivina advena Cushman, undescribed variant Buliminella subfusiformis Cushman Epistominella? sp. Nonion aff. N. costiferum (Cushman) Locality m182 Bolivina tumida Cushman var. Bolivina cf. B. decurtata Cushman Bolivina cf. B. subadvena Cushman Buliminella curta Cushman Buliminella subfusiformis Cushman Nonion aff. N. costiferum (Cushman) Suggrunda kleinpelli Bramlette V alvulineria depressa Cushman Locality m183 EL MODENO VOLCANICS Bolivina decurtata Cushman Bolivina sinuata alisoensis Cushman and Adams Bolivina tumida Cushman Bulimina montereyana Kleinpell Buliminella subfusiformis Cushman Epistominella gyroidinaformis (Cushman and Goudkoff) Epistominella relizensis (Cushman and Kleinpell) Nonion pizarrensis W. Berry V alvulineria californica obesa Cushman misa MONTEREY SHALE Bolivina advena striatella Cushman Bolivina decurtata Cushman Bolivina interjuncta bicostata Cushman Bolivina marginata gracillima Cushman Bolivina obliqua Barbat and Johnson Bolivina tumida Cushman Bolivina cf. B. woodringi Kleinpell Buliminella curta Cushman Buliminella subfusiformis Cushman Cassidulina limbata Cushman and Hughes Cassidulina cf. C. margareta Karrer Cibicides sp. Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides dOrbigny Gyroidina rotundimargo R. E. and K. C. Stewart Nonion costiferum (Cushman) Planulina ornata dOrbigny Suggrunda kleinpelli Bramlette Uvigerina subperegrina Cushman and Kleinpell ''Uvigerinella'' californica Cushman, undescribed variant I U 1 }j> OQj> - 4 O H d b> id d C > ag bd Pd d 4 Q Q Q o rq 20 20 +d 20 g Hj bd bd bd bd bd bd bd bod bd bd n bo bd bd h d Baggina californica Cushman Bolivina decurtata Cushman Bolivina ef. B. barbarana Cushman and Kleinpell Bolivina ef. B. woodringi Kleinpell Boliminella curta Cushman Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny Planulina ornata dOrbigny Suggrunda kleinpelli Bramlette Uvigerina subperegrina Cushman and Kleinpell PUENTE FORMATION LA VIDA MEMBER Locality m186 Bolivina decurtata Cushman Bolivina rankini Kleinpell Bolivina sinuata alisoensis Cushman and Adams Bolivina tumida Cushman Buliminella curta Cushman Cibicides illingi (Nuttall) Epistominella pacifica (RE. and K. C. Stewart) Uvigerina subperegrina Cushman and Kleinpell ''Uvigerinella'' californica Cushman, undescribed variant Locality m187 Baggina californica Cushman Bolivina decurtata Cushman Bolivina sinuata alisoensis Cushman and Adams Buliminella ecuadorana Cushman and Stevenson Epistominella gyroidinaformis (Cushman and Goudkoff) ''Uvigerinella'' californica Cushman Locality m188 Bolivina barbarana Cushman and Kleinpell Bolivina cf. B. decurtata Cushman Bolivina sinuata alisoensis Cushman and Adams Bolivina tumida Cushman Buliminella ecuadorana Cushman and Stevenson Epistominella subperuviana (Cushman) V alvulineria ef. V. grandis Cushman and Galliher V alvulineria cf. V. williami Kleinpell Locality m189 Bolivina decurtata Cushman Bolivina sinuata alisoensis Cushman and Adams Buliminella curta Cushman Uvigerina joaquinensis Kleinpell V alvulineria cf. V. grandis Cushman and Galliher Locality m190 Buliminella ecuadorana Cushman and Stevenson Epistominella relizensis (Cushman and Kleinpell) Epistominella subperuviana (Cushman) ''Uvigerinella'' californica Cushman, undescribed variant Locality m191 Bolivina sinuata alisoensis Cushman and Adams Bolivina tumida Cushman Bolivina cf. B. marginata gracillima Cushman Pd bo bo bd ey bd bd bd bu je bd bu bo bo bd Po id id ag C bo d d >> H o bd Hg be - bo bo i> bo 0 Po bo bd q be bd bd bod bd ag C bd ed d 2d d d D97 D98 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA Locality m191-Continued Bolivina cf. B. vaughani Natland Buliminella ecuadorana Cushman and Stevenson Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny Uvigerina joaquinensis Kleinpell Uvigerina subperegrina Cushman and Kleinpell Locality m192 Angulogerina? sp. Bolivina decurtata Cushman Bolivina interjuncta bicostata Cushman Bolivina sinuata alisoensis Cushman and Adams Bolivina tumida Cushman Bolivina cf. B. vaughani Natland Buliminella curta Cushman Bulimina uvigerinaformis Cushman and Kleinpell Cibicides illingi (Nuttall) Epistominella subperuviana (Cushman) Globigerina bulloides d'Orbigny Robulus smileyi Kleinpell Uvigerina subperegrina Cushman and Kleinpell Valvulineria cf. V. grandis Cushman and Galliher Locality m193 Bolivina cf. B. interjuncta bicostata Cushman Bolivina pseudospissa Kleinpell Bolivina cf. B. vaughani Natland Globigerina bulloides d'Orbigny Robulus smileyi Kleinpell Uvigerina subperegrina Cushman and Kleinpell Valvulineria cf. V. grandis Cushman and Galliher Locality m194 Bolivina decurtata Cushman Buliminella curta Cushman Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny Suggrunda kleinpelli Bramlette Valvulineria cf. V. grandis Cushman and Galliher Locality m195 Bolivina decurtata Cushman Bolivina marginata gracillima Cushman Bolivina sinuata alisoensis Cushman and Adams Bolivina cf. B. vaughani Natland Buliminella ecuadorana Cushman and Stevenson Epistominella relizensis (Cushman and Kleinpell) Gyroidina sp. Valvulineria cf. V. grandis Cushman and Galliher Locality m196 Bolivina decurtata Cushman Bolivina marginata gracillima Cushman Bolivina cf. B. salinasensis Kleinpell Bolivina cf. B. subhughesi Kleinpell Bolivina cf. B. vaughani Natland Bulimina delreyensis Cushman and Galliher Bulimina cf. B. pseudoaffinis Kleinpell Bulimina uvigerinaformis Cushman and Kleinpell Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Eponides rosaformis Cushman and Kleinpell Globigerina bulloides d'Orbigny Uvigerina cf. U. subperegrina Cushman and Kleinpell Virgulina californiensis Cushman Locality m197 Bolivina californica Cushman Bolivina girardensis Rankin m 50 bd Hq bd bd bd bd i> bd bd bu bud bd bd bd bo bd |e bo D Q Q 3 Q a 0 U C P0 ig h bo P0 PJ hy B0 BO hq hg ) ego ego ee bd B0 B0 2 I i ag O ad i O 20 +g Locality m197-Continued Bolivina modeloensis Cushman and Kleinpell Bolivina obliqua Barbat and Johnson Bolivina sinuata alisoensis Cushman and Adams Bolivina cf. B. subhughesi Kleinpell Bolivina cf. B. vaughani Natland Bulimina delreyensis Cushman and Galliher Bulimina cf. B. pseudoaffinis Kleinpell Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Eponides rosaformis Cushman and Kleinpell Planulina ornata dOrbigny Valvulineria cf. V. grandis Cushman and Galliher Locality m197a Bolivina girardensis Rankin Bolivina cf. B. pseudospissa Kleinpell Bolivina cf. B. vaughani Natland Bolivina woodringi Kleinpell Buliminella curta Cushman Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Gyroidina sp. Nonion cf. N. pizarrensis W. Berry Uvigerina joaquinensis Kleinpell Locality m199 Bolivina cf. B. decurtata Cushman Bolivina woodringi Kleinpell Bulimina delreyensis Cushman and Galliher Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny Gyroidina sp. Nonionella miocenica (Cushman) Uvigerina joaquinensis Kleinpell Valvulineria cf. V. grandis Cushman and Galliher LA VIDA AND YORBA MEMBERS UNDIFFERENTIATED Locality m200 Bolivina californica Cushman Bolivina decurtata Cushman Bolivina marginata gracillima Cushman Bolivina sinuata alisoensis Cushman and Adams Bolivina cf. B. vaughani Natland Bulimina wigerinaformis Cushman and Kleinpell Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny Suggrunda kleinpelli Bramlette Uvigerina subperegrina Cushman and Kleinpell YORBA MEMBER Locality m201 Bolivina marginata gracillima Cushman Bolivina sinuata alisoensis Cushman and Adams Bolivina cf. B. subhughesi Kleinpell Bolivina cf. B. vaughani Natland Buliminella cf. B. pseudoaffinis Kleinpell Bulimina wvigerinaformis Cushman and Kleinpell Buliminella curta Cushman Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Eponides rosaformis Cushman and Kleinpell Globigerina bulloides d'Orbigny Valvulineria cf. V. grandis Cushman and Galliher Locality m202 Bolivina decurtata Cushman P0 i> b P0 C Pd bd i bd = bd bd bd eg bd bd bu (> bo bd P0 20 Pd i bu hd bd bd C bo bd bd Pd b > P0 bd bu bo bod bd bo Q - a i bio d bd 2d bod bd C j bd bo GEOLOGY OF THE SANTA ANA MOUNTAINS Locality m202-Continued Bolivina cf. B. vaughani Natland Bolivina woodringi Kleinpell Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny Hopkinsina magnifica Bramlette Locality m204 Bolivina decurtata Cushman Bolivina girardensis Rankin Bolivina cf. B. vaughani Natland Bolivina cf. B. woodringi Kleinpell Buliminella curta Cushman Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Gyroidina rotundimargo R. E. and K. C. Stewart Uvigerina subperegrina Cushman and Kleinpell LA VIDA AND YORBA MEMBERS, UNDIFFERENTIATED Locality m205 Bolivina obliqua Barbat and Johnson Bolivina tumida Cushman Bolivina cf. B. vaughani Natland Buliminella subfusiformis Cushman Epistominella relizensis (Cushman and Kleinpell) Globigerina bulloides d'Orbigny PLIOCENE FERNANDO FORMATION Locality m206 Bolivina pisciformis Galloway and Wissler Bolivina pocheensis White Bolivina pygmaea H. B. Brady Bulimina cf. B. affinis dOrbigny Bulimina subacuminata Cushman, R. E. and K. C. Stewart Buliminella elegantissima d'Orbigny Cassidulina spiralis Natland Cassidulina subglobosa H. B. Brady Cassidulina translucens Cushman and Hughes Cibicides mekannai Galloway and Wissler Epistominella pacifica (RE. and K. C. Stewart) Epistominella subperuviana (Cushman) Gyroidina rotundimargo R. E. and K. C. Stewart Marginulinopsis capistranoensis White Uvigerina peregrina Cushman Virgulina nodosa R. E. and K. C. Stewart Locality m207 Bolivina pisciformis Galloway and Wissler Bolivina pocheensis White Cassidulina cushmani (R. E. and K. E. Stewart) Epistominella subperuviana (Cushman) Globigerina bulloides d'Orbigny Globobulimina pacifica Cushman Hanzawaia cf. H. concentrica (Cushman) Pullenia quinqueloba (Reuss) Robulus cf. R. americanus Cushman Uvigerina peregrina Cushman Locality m208 Angulogerina carinata Cushman Bolivina pisciformis Galloway and Wissler Bulimina subacuminata Cushman, R. E. and K. C. Stewart 20 0 O a P0 ag O d O 7 > d i O > Pd bd bd Pd 2d J a a w = F J = }» bd bo bd bd be Ha bud bu bd bu (> bd bd Hed bu bu bu bd bd bd bd D99 Locality m208-Continued Cassidulina cushmani R. E. and K. C. Stewart Cassidulina subglobosa H. B. Brady Cassidulina translucens Cushman and Huges Cheilostomella ovoidea Reuss Cibicides mckannai Galloway and Wissler Entosolenia sp. Epistominella pacifica (RE. and K. C. Stewart) Epistominella subperuviana (Cushman) Glandulina laevigata d'Orbigny Globigerina bulloides d'Orbigny Globobulimina pacifica Cushman Nonionella translucens (Cushman) Orbulina universa d'Orbigny Pullenia quinqueloba (Reuss) Robulus cf. R. americanus Cushman Stilostomella lepidula (Schwager) Uvigerina peregrina Cushman Valvulineria araucana d'Orbigny Virgulina cornuta Cushman P0 Pd ij bu bd bd bd bd bd bu bd bd Pd bd bd bd O n 5d MEGAFOSSIL LOCALITIES LATE CRETACEOUS LADD FORMATION BAKER CANYON CONGLOMERATE MEMBER No. usedPermanent Field No. Collected by- Description of locality in this U.S. Geo- report logical Survey No. Fi Fla Fib Fle F2 F3 F4 F5 F6 25034 25305 25036 25037 25038 25039 S116 C. H. Gray and In Mabey Canyon, 2,730 m J. E. Schoellhamer. 8,950 ft) south and 215 m 700 ft) east of the northeast corner of the Black Star Canyon quadrangle. Not plotted, east of area shown on geological map, plate 1. W. P. Popeno®e......_..... Bluffs at base of sandstone, 0.8 km (0.5 mi) north of Silverado Canyon, west side of Ladd Can- on. Lowermost fossiliferous eds exposed. (Calif. Inst. Tech. loc. 1292.) Limy sandstone bed near base of shale. South of roadcut at Holz's Ranch. This locality may become obscured by slides. Sil- verado Canyon. (Calif. Inst. Tech. loc. 82K ___________ do............... In sandstone above conglomerate, at fork of Ladd and Silverado Carzyon. (Calif. Inst. Tech. loc. 80. $73 J. E. Schoellhamer....... Near head of Mabey Canyon, 4,245 m $13,925 ft) south and 1,310 m (4,300 ft) west of the northeast corner of the Black Star Canyon quadrangle, eleva- tion 768 m (2,520 ft). SBS .. s llc - Near head of Coal Canyon, 2,775 m (9,100 ft) south and 3,580 m (11,750 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 755 m (2,480 ft). SBT! ". Aereceveees Oath: On divide between Coal Canyon and Fremont Canyon, 3,230 m (10,600 ft) south and 3,675 m (12,050 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 750 m (2,460 ft). J.. Veddet ........:..... In Black Star Canyon, 8,915 m £29250 ft) south and 1,950 m 6,400 ft) west of the northeast corner of the Black Star Canyon uadrangle, elevation 640 m 2,100 ft). ........... do............... In Black Star Canyon, 8,475 m $7,800 ft) south and 1,880 m 6,175 ft) west of the northeast corner of the Black Star Canyon uadrangle, elevation 700 m 2,300 ft). D100 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this .S. Geo- in this U.S. Geo- report - logical report - logical Survey No. Survey No. F7 Pomona _ A. 0. Woodford,. In Silverado Canyon, 185 m (600 | 21 25052 S66 W. P. Popenoe and Near divide between Fremont College _ J. G. Vedder, ft) south and 1,435 m (4,700 J. E. Schoellhamer. Canyon and Black Star Canyon, Locality _ and others. ft) west of the northeast corner 5.730 m (18,800 ft) south and 46 of the El Tor? quadraglgle, ele- 1,85: m t(5,950 ft) fwaft oBtl thfi vation 385 m (1,260 ft). northeast corner of the Blac F8 _ 25040 A In Silverado Canyon, 360 m Minoo ira sore redone ara | hts BN: Concretions in shale 30 m (100 corner of the El Toro quad- ft) abovg st_rdeamfars1d aed (6305 rangle, elevation 415 m (1,360 on About sto m (oen an t). G s ick north of road fork in Santiago F9 25041 S61 J. E. Schoellhamer....... Near head of Fremont Canyon, Canyon at Harding Canygn ggg m 61151515500 ff? so‘tthfmfid Juriction. (Calif. Inst. Tech. loc. + m 250 ft) west of the 92. sr tamo | ths boss JG Vedder..;.......... In Baker Canyon, 10,015 m tion 670 m (2,200 ft. (2250 10 mest of the northeast F10 25042 S65 -A L.. Ore e Near divide between Fremont corner of the Black Star Canyon Canyéon aild Béacaktfifar Caflxyond. uadrangle, elevation 585 m 5,775 m (18,950 ft) south an 1,920 ft). Afrigefséigfferfilfwffi if]??? Fos) - 25054 .._ om cials. Near mouth of Blind Canyon, Star Canyon quadrangle, eleva- gig? hg 532186150ng soutthfzztfid tion 700 m (2,300 ft). 116111191351 corner ofwtise %lac§ Fil 25043 S64 is cll 00. .- Near divide between Fremont Star Canyon quadrangle, eleva- Canyon and Black Star Canyon, tion 245 m (800 ft). i222 I: §égd§goftf>flwigltngffig F24 ... rect. aul In Baker Canyon 10,255 m f 4 33,650 ft) south and 2,570 m northeast corner of the Black 8.425 ft) t of th theast Star Canyon quadrangle, eleva- 4 eh las ra tion 725 m (2.380 ft) cornder of the Bllack Star Canyon i ' uadrangle, elevation 490 m F12 25044 S12 0 HO Near head of Fremont Canyon, 1,600 ft). tok Amen exit | reas P4-35 - W. P. Popenoe............ About 90 m (300 ft) due south of northeast corner of the Black 15125?) (Calif. Inst. Tech. lo¢ Star Canyon quadrangle, eleva- * tion 795 m (2,600 ft). F24b P385 C- L.. \o whi acte Crest of small north-south F13 25045 STL Lo- loll eels CO ester Near head of Fremont Canyon, frendmg Put. beiwegn firsghtw‘} 4,070 m (13.350 ft) south and ee dbus moth af morth io 2.560 m (8.400 ft) west of the Harding Canyon. About 760 m northeast corner of the Black (2,500 ft) N. 26, w. of the Slt miatranile: dee wap Ur tion m (2,400 ft). : " shale section, Black Star Ca- F14 25046 J. G. Vedder :...:.:....... Near Mustang Spring, 13.615 m nyon quadrangle. (Calif. Inst. §§4égg5fl§0 sout}; tahnd 1,6}115 m Tech. loc 1162} v west of the northeast R A corner of the Black Star Canyon F24c P184 "assit First prominent - northeast: s southwest spur north of San- u32%53?§le, elevation 385 m tiago Creek. About 915 m 1,260 ft). >, 4 (3,000 ft) straight west of the F15 . kel d n no In Black Star Canyon near Hidden dam in HardinggCanyon. Pebbly Ranch, 7,530 m (24,700 ft) lens near top of shale sequence south and 2,005 m (6,575 ft) 'T. pescaderoensis zone") just vatBolf tllzesnortlgast corner gt” below crest ofdridge. BlafléStar the Black Star Canyon quad- Canyon quadrangle. alif. rangle, elevation 630 m (2,060 Inst.yTech.qloc 1053. ft). F24d P49-38. ... -. Crest of long spur extendin F16 25048 A. E. Near Mustang Spring, 13,745 m northeast from CCC camp, an 45,100 ft) south and 1,570 m at a point 1,095 m (3,600 ft) 5,150 ft) west of the northeast straight west of dam in Harding corner of the Black Star Canyon Canyon. SW 1/4 NW 1/4 sec. gixdexbatggle, elevation 400 m 29, i," 5 S., R. 7 W., Black Stlelu v t). Canyon quadrangle. Turritella chicoensis beds at top of shale £4" 29049 J. G. Vedder.............. Infiéaglgosmrsgfgaygfia 21,2325; z: section. (Calif. Inst. Tech. loc 12,050 ft) west of the north- east corner of the Black Star F25 25056 J. G. Vedder In Black Star Canyon, 8,550 m Canyon quadrangle, elevation $28,050 ft) south and 3,340 m 480 m (1,580 ft). 10,950 ft) west of the north- F8 25050 A. E. Altinli and east corner of the Black Star J. G. Vedder Near Mustang Spring, 12,850 m Canyon quadrangle, elevation (42,150 fo) 'south and 1465, m 590 m (1,940 ft). 4,800 ft) west of the northeast F26 25087 L nt o Otol ly Owe: se On divide between Black Star Ca- corner of the Black Star Canyon nyon and Baker Canyon, 10,135 uadrangle, elevation 580 m m é33,250 ft) south and 2,935 1,900 ft). m (9,625 ft) west of the north- east corner of the Black Star norz siate mEmore l F27 25058 $1924 D. M. Kinney and In tributary of Fresno Canyon, P19= J. E. Schoellhamer 1,080 m (3,550 ft) south and F19 25051 $190 D. M. Kinney and 2,470 m (8,100 ft) west of the J. E. Schoellhamer. _ Divide near Oak Flat, 5,290 m northeast corner of the Black 17,350 ft) south and 1,785 m Star Canyon quadrangle, eleva- 5,850 ft) west of the northeast tion 415 m (1,360 ft). f cvanch Camen |- Fos: _ spose 4.0: Vedder 111521315183 fgfanyohn, atas 8 4 5 t) south an 405 m 2,580 ft). ' } ® 30,850 ft) west of the north- F20 Pomona _ Richard Ten Eyck In Williams Canyon, 2,360 m east corner of the Black Star College 57,750 ft) south and 625 m Canyon quadrangle, elevation locality 2,050 ft) west of the northeast 280 m (920 ft). 142 corner of the El Toro quad: F29 25060. . a> +s) ans ooo ande Between Baker Canyon and Mus- fingle, elevation 400 m (1,320 t). tang Spring, 13,175 m (43,225 ft) south and 2,485 m (8,150 GEOLOGY OF THE SANTA ANA MOUNTAINS D101 No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this U.S. Geo- in this U.S. Geo- report lsogical > report lsogical urvey No. urvey No. F29 -Continued ft) west of the northeast corner | | p38 25069 ser ian nerecee Between Fremont Canyon and of the Black Star Canyon quad- Oak Flat, 4,830 m (15.850 ft rangle, elevation 480 m (1,580 south and 2.985 m (9.800 ft ft). west of the northeast corner of F30 25061 Fees ttc L COS Between Baker Canyon and Mus- the Black Star Canyon quad- tang Spring, 13,555 m (44.475 rangle, elevation 560 m (1,840 ft) south and 2,120 m (6,950 ft). ftf) west of the northeast corner | F39 25070 SBD le ' " Between Fremont Canyon and of the Black Star Canyon quad- Oak Flat, 4,745 m (15,575 ft) angle. elevation 465 m (1,530 south and 3,050 m (10,000 ft) t). west of the northeast corner of F31 _ 25062 D. M. Kinney and In Baker Canyon 11.795 m the Black Star Canyon quad- J. E. Schoellhamer $38,700 13>) south afndh3200 s wale, elevation 565 m (1,860 10,500 ft) west of the north- * east corner of the Black Star | F4Q 25071 Védder -...... In Baker Canyon, 11.035 m Canyon quadrangle, elevation 836,200 ft) south and 3,170 m 450 m (1,480 ft). 10,400 ft) west of the north- F32 25063 JG. Vedder ...s:....l.c.. In Baker Canyon 11,295 m east corner of the Black Star $37,050 ft) south and 3.170 m Canyon quadrangle, elevation 10,400 ft) west of the north- 550 m (1,800 ft). east corner of the Black Star | F41 _ 25072 NF o OO On divide between Baker Canyon Canyon quadrangle, elevation and Hall Canyon, 12,300 m 465 m (1,520 ft). 240,350 ft) south and 2.935 m F33 25064 AE; On divide between Baker Canyon 9,625 ft) west of the northeast and Black Star Canyon, 10,195 corner of the Black Star Canyon m ((3364580ft)fs)0uth and f3,0}810 111105383 le, elevation 450 m m (10.1 t) west of the « * northeast corner of the Black | p42 25073 S54 J. E. Schoellhamer........ Near divide between Gypsum Star Canyon quadrangle, eleva- Canyon and Fremont Canyon, tion 545 m (1,780 ft). 4,870 m (15.975 ft) south and F34 25065 J. In Silverado Canyon, 490 m 5,560 m (18,250 ft) west of the 1,600 ft) south and 2.085 m northeast corner of the Black 6,850 ft) west of the northeast Star Canyon quadrangle, eleva- corner of the El Toro quad- tion 580 m (1,900 ft). angle. elevation 340 m (1,120 F43 25074 J. G. Vedder .............. Ne(ar Santiago coal mine, 9,950 m - 32,650 ft) south and 6,385 m F34a -- P12-85 - W.P.Popenoe............ South side of second ridge north- (20,950 ft) west of the north- west of Holz ranch house, just east corner of the Black Star east of small gully and about 30 Canyorz qu;d1;a)ngle, elevation m (100 ft) stratigraphically 365 m (1,200 ft). below basal conglomerate of Williams Formation, 915 m s s 3 (3,000 ft) northwest of Holz PLEASANTS SANDSTONE MEMBER ranchhouse, and approximately in center of the NW 1/4 SE 1/4 sec. 7. T. 5 S.. R. 7 W. (Calif. F44 U.C.L.A. - Louella Saul and In Bee Canyon, 4,628 m (15,150 Inst. Tech. loc. 1173.) locality _ Richard Saul. ft) south and 7.985 m (26,200 F34b = -- PHSB - L... On crest of second ridge north- 2819 it; glisiffrgfiz nt;‘3:::tl§°"}er west from Holz ranchhouse, F a es, els About 1,035 m (3,400 ft) N. 40° yablon 200 m (600 10). . from the ranchhouse and F45 25075 JG. Vedder .............. Between Black Star Canyon and 30+ m (100 ft) below basal Baker Canyon, 11,325 m conglomerate of Williams For- $7,150 ft) south and 3,460 m mation. Silverado Canyon. 11,350 ft) west of the north- (Calif. Inst. Tech. loc. 1172. east corner of the Black Star F34c -- P10-34 _ W. P. Popenoe and Left bank of Williams Canyon, ff??? 111515326“ng glesation G. H. Anderson. just above stream bed, 390 m " % (1,275 ft) S. 87° W. of the | F46 25076 S56 J. E. Schoellhamer ...... Near divide between Gypsum Schulz ranchhouse and about Canyon and Fremont Canyon, 455 m (1,500 ft) straight east 5,120 m (16,800 ft) and 5,800 of the juncture of Williams and m (19,000 ft) west of the Santiago Creeks. Uppermost northeast corner of the Black beds of the Turritella chicoensis Star Canyon quadrangle, eleva- zone of Packard. (Calif. Inst. tion 495 m (1,630 ft). Tech. loc. 94. F47 25077 J. G. Vedder .............. Between Williams Canyon and F344 - -- BN: Sandstone just above shale about Santiago Creek, 3,370 m 90 m (300 ft) east of section 511,050 ft) south and 1,190 m line on ridge north of Williams 3,900 ft) west of the northeast Cafiyon. (Calif. Inst. Tech. loc. cornler elf the E}, Toro (quad- 94. rangle, elevation 555 m (1,820 F35 25066 J: G.NVedder ............ In Baker Canyon, 12,220 m ft). 540,100 ft) south and 3,210 m | F48 25078 dire ol OO Between Fremont Canyon and 10,525 ft) west of the north- Gypsum Canyon, 6,500 m east corner of the Black Star $1,325 ft) south and 6.980 m Canyon quadrangle, elevation 22,900 ft) west of the north- 340 m (1,120 ft). ecast corner gf th? Blalck Star F36 25067 Rife: UOS. racked Between Silverado Canyon and 4:51“)? lqua angle, elevation ya 440 ft). will C . 1,645 is* 251,46???) 533mm 1,400 2 F4a9 _ 25079 poe 0 o In Fremont Canyon, 7,420 m 4,600 ft) west of the northeast 524.350 ft) south and 5,745 m corner of the El Toro quad- 18,850 ft) west of the north- rangle, elevation 505 m (1,650 east corner of the Black Star ft). gggyorz lqélsagléxzngle. elevation m (1, t). ® F50 25080 FTE DEL In Fremont Canyon, 7,100 m WILLIAMS FORMATION $23,300 ft) south and 5,945 m 19,500 ft) west of the north- SCHULZ RANCH SANDSTONE MEMBER East corner an" thtle Black Star anyon quadrangle, elevation 445 m (1,460 ft). F37 25068 $188 W. P. Popenoe and In Black Star Canyon, 7,955 m F51 25081 rrr Porte d J. E. Schoellhamer £26,100 ft) south and 3,095 m Tires C ;;%1616) I}; Sf‘fiffifidséflf) g) 10,150 ft) west of the north- 521350 10) west of the north- east corner of the Black Star east corner of the Black Star sqft co ses » + m (1, f D102 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this U.S. Geo- in this U.S. Geo- report - logical report - logical Survey No. Survey No. F52 25082 Fri . dO In Fremont Canyon, 9,300 m F66 25096 .... Between Fremont Canyon and 530,175 “l south and 6,690 m Black Star Canyon, 9,625 m 26,350 ft) west of the north- E31,575 ft; south and 5,760 m east corner of the Black Star 18,900 ft) west of the north- Canyon quadrangle, elevation east corner of the Black Star 235 m (770 ft). Canyon quadrangle, elevation FS3 0 25038 | -- J. G. Vedder On divide between Fremont Can- seo m (1,200 40: J. E. Schoellhamer. yon and Black Star Canyon, 8,800 m (28,875 ft) south and 4,800 m (15,750 ft) west of the northeast corner of the Black Star Canyon quadrangle, eleva- tion 650 m (2,130 ft). F54 25084 J. G. Vedder.............: Between Baker Canyon and Mus: tang Spring, 13,345 m (43,775 ft) south and 2,790 m (9,150 ft) west of the northeast corner of the Black Star Canyon quad- angle, elevation 435 m (1,420 t). F55 25085 for oin Near mouth of Black Star Can- yon, 10,425 m (34,200 ft) south and 4,710 m (15,450 ft) west of the northeast corner of the Black Star Canyon quad- angle, elevation 390 m (1,280 t). F56 25086 Aar Ms ORs Between Irvine Park and Irvine Lake, 9,355 m (30,700 ft) south and 10,015 m (32,850 ft) west of the northeast corner of the Black Star Canyon quad- ra)ngle, elevation 295 m (960 ft). F57 25087 ANTON .s" eveceeeesect In Fremont Canyon, 9,335 m 530.625 “l south and 7,770 m 25,500 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 285 m (940 ft). F58 25088 see Te Uo oe eee caves Between Blind Canyon and Fre- mont Canyon, 8,580 m (28,150 ft) south and 8,470 m (27,800 ft) west of the northeast corner of the Black Star Canyon quad- angle, elevation 325 m (1,060 t). F59 25089 SHEEN Do Between Williams Canyon and Santiago Creek, 2,515 m 8,250 ft) south and 1,730 m 5,675 ft) west of the northeast corner of the El Toro quad- fingle, elevation 455 m (1,500 t). F6O 25090 $53 J. E. Schoellhamer....... Near divide between Gypsum Canyon and Fremont Canyon, 4,770 m (15,650 ft) south and 6.370 m (20,900 ft) west of the northeast corner of the Black Star Canyon quadrangle, eleva- tion 505 m (1,660 ft). F61 25091 J. G. Vedder Between Weir Canyon and Blind Canyon, 6,645 m (21,800 ft) south and 10,180 m (33,400 ft) west of the northeast corner of the Black Star Canyon quad- angle, elevation 315 m (1,030 t). F62 25092 J. G. Vedder Between Fremont Canyon and J. E. Schoellhamer Black Star Canyon, 10,050 m 532,975 ft) south and 5,015 m 16,450 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 450 m (1,470 ft). F63 25093 3. G. Vedder .............. Between Black Star Canyon and Baker Canyon, 1,180 m $38,750 ft) south and 3,680 m 12,075 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 330 m (1,080 ft). F64 25094 Fete tobe Orel Between Weir Canyon and Blind Canyon, 7,475 m (24,525 ft) south and 9,995 m (32,800 ft) west of the northeast corner of the Black Star Canyon quad- angle, elevation 340 m (1,120 t). F65 25095 FEET Between Fremont Canyon and Black Star Canyon, 9,785 m £32,100 ft) south and 5,975 m 19,600 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 465 m (1,520 ft). F67 F68 F69 F70 F71 F7la F71b F72 F73 F74 F75 F76 F77 F78 25097 25098 25099 25100 25101 25102 25103 25104 25105 25106 25107 25108 ............ do.............. Between Blind Canyon and Fre- mont Canyon, 8,695 m 528,525 ft) south and 8,335 m (27,350 ft) west of the northeast corner of the Black Star Canyon quad- fingle, elevation 315 m (1,030 t). ............ do.............. Between Blind Canyon and Fre- mont Canyon, 8,595 m $8,200 “l south and 8,190 m (26,875 ft) west of the northeast corner of the Black Star Canyon quad- angle, elevation 335 m (1,100 t). ............ do.............. On divide between Blind Canyon and Fremont Canyon, 7,735 m $25,375 ft) south and 8,090 m 26,550 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 425 m (1,400 ft). ............ do.............. Between Irvine Park and Blind Canyon, 8,315 m (27,275 ft; soutll and 10,805 m (35,450 ft west of the northeast corner of the Black Star Canyon quad- angle, elevation 225 m (730 t). D. M. Kinney Between Black Star Canyon and J. E. Schoellhamer Baker Canyon, 10,815 m and J. G. Vedder 535,475 it; south and 3,795 m 12,450 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 435 m (1,420 ft). B. N. Moore............... Thin limy sandstone bed on Santiago-Aliso divide 805 m 0.5 mi) east of county road. Calif. Inst. Tech. loc. 86.) P15-33 _ W. P. Popence Crest of first east-west spur south G. H. Anderson of Williams Canyon, in the NW 1/4 NE 1/4 sec. 19, T. 5 S., R. 7 W., Black Star Canyon quad- rangle. Limestone beds in upper sandstone sequence. (Calif. Inst. Tech. loc. 976.) J; G, Vedder .............. Between Fremont Canyon and Ir: vine Lake, 9,730 m $31,925 ft; south and 7,680 m (25,200 ft west of the northeast corner of the Black Star Canyon quad- fingle, elevation 365 m (1,200 t). ____________ do.............. Between Silverado Canyon and Williams Canyon, 1,770 m £5,800 ft) south and 1,830 m 6,000 ft) west of the northeast corner of the Black Star Canyon uadrangle, elevation 420 m 1,370 ft). ____________ do.............. Near divide between Gypsum Canyon and Fremont Canyon, 5,195 m (17,050 ft) south and 6,095 m (20,000 ft) west of the northeast corner of the El Toro uadrangle, elevation 510 m 1,680 ft). ............ do.............. In Fremont Canyon, 6,735 m 522,100 ft) south and 6,525 m 21,400 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 415 m (1,360 ft). ............ do.............. In Blind Canyon, 7,019 m $3,000 ft) south and 8,570 m 28,100 ft) west of the north- east corner of the Black Star Canyon quadrangle, elevation 365 m (1,200 ft). ............ do.............. Near divide between Blind Can- yon and Fremont Canyon, 7,770 m (25,500 ft) south and 7,390 m (24,250 ft) west of the northeast corner of the Black Star Canyon quadrangle, eleva- tion 395 m (1,300 ft). dG, Vedder ....-:......- Between Fremont Canyon and Black Star Canyon, 9,980 m GEOLOGY OF THE SANTA ANA MOUNTAINS D103 No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this - U.S. Geo- in this - U.S. Geo- report - logical report - logical Survey No. Survey No. F78-Continued 532,750 ft) south and 5,300 m | rgj1 18987 J.G. Vedder .............. Near divide between Gypsum 17,400 ft) west of the north- Canyon and Blind Canyon, east corner of the Black Star 5,915 m (19,400 ft) south and Canyon quadrangle, elevation 7,195 m (25,575 ft) west of the 475 m (1,560 ft). gorthéaast comm;1 of tlhe Bllack F79 25109. ren n ntsc 101-1 she Near Irvine Peak, 8,580 m tar Canyon quadrangle, eleva- $28,150 ft) south and 11,050 m tion 420 m (1,380 ft). 36,250 ft) west of the north- | r92 18988 D. M. Kinney, On divide between Gypsum Can- east corner of the Black Star J. E. Schoellhamer, yon and Fremont Canyon, 5,685 Canyon quadrangle, elevation and W. P. Woodring m (18,650 ft) south and 7,795 210 m (695 ft). m (23,975 ft) west oil‘althe __________________________ Between Fremont Canyon and northeast corner of the Black F8o 25110 do Blaeci Star Canyon, 5,725 in Star Canyon quadrangle, eleva- £31,900 ft) south and 4,505 m tion 490 m (1,600 ft). 14,775 ft) west of the north- | rg3 18989 A. E. Altinli and Near divide between Gypsum east corner of the Black Star J. G. Vedder Canyon and Fremont Canyon, Canyon quadrangle, elevation 6,050 m (19.850 ft) south and 480 m (1,580 ft). 7,21?I m (23,675 ft)fwest (latithle‘ F8Oa P55-33 - W. P. Poenoe .__________. Crest of low spur directly north- northeast corner of the Blac east of Pleasants ranchhouse, Star Canyon quadrfggxgle, eleva- and just north of Williams Can- tion 510 m (1,670 ft). yon 500 m (1,650 ft) N. 41° E. | rg4 18990 Verder Near divide between Gypsum of mouth of Williams Canyon. Canyon and Fremont Canyon, Near top of upper sandstone 6,120 m (20,075 ft) south and sequence. (Calif. Inst. Tech. 6,515 m (21,375 ft) west of the loc. 977.) northéeast cometi of tlhe Black F810 - 25111 J. G. Vedder .............. In Black Star Canyon, 10,670 m Star Canyon quadrangle, eleva- (35.000 ft) south and 4.715, m tion 495 m (1,625 ft). 15,475 ft) west of the north- | F95 Pomona _ ..______._... 7" te m Near mouth of Weir Canyon, east corner of the Black Star College 7,110 m (23,325 ft) south and Canyon quadrangle, elevation locality 135 m (450 ft) west of the 335 m (1,100 ft). 160 northeast corner of the Orange Pes? - ... 1.0... dole In Blind Canyon, 6,585 m uadrangle, elevation 290 m . $21,600 ft) south and 8,860 m 950 ft). 29,075 ft) west of the north- | F96 VAG Aer ene Between Weir Canyon and Irvine east corner of the Black Star Park, 7,940 m (26,050 ft) south Canyon quadrangle, elevation and 10,980 m (36,025 ft) west 345 m (1,140 ft). of the northeast corner of the Black Star Canyon quadrangle, elevation 300 m (980 ft). PALEOCENE F97 1999100 cod sonce Or Betweinfremont Canyon and Irv- n ine Lake, 10,270 m (33,700 ft SILVERADO FORMATION south and 7.835 m §25,700 ft; west of the northeast corner of % the Black Star Canyon quad- F83 Y92A R.-F.Yerkes............... Gladding McBean claypit, 680 m rangle, elevation 310 m (1,025 2,225 ft) south and 120 m ft). 400 ft) east of the northeast | rog A. E. Altinli ....____.____.__. Between Fremont Canyon and Irv corner of the Black Star Canyon ine Lake, 10,235 m 533,575 ft) quadrangle. Not plotted east of south and 6,555 m (21,500 ft) area shown on geologic map, west of the northeast corner of plate 1. the Black Star Canyon quad- F84 18981 $26 J. E. Schoellhamer....... On Santa Ana Canyon Road, 260 rangle, elevation 355 m (1,160 m (850 ft) south and 6,385 m ft). (20,950 ft) west of the north- | r99 18992 A. E. Altinli and Between Fremont Canyon and Iry- east corner of the Black Star J. G. Vedder ine Lake, 10,455 m 534.300 ft) Canyon quadrangle, elevation south and 6,735 m (22,100 ft) 130 m (420 ft). west of tllzesnortiéeast corner sf , 920 the Black Star Canyon quad- FBS 18982 $101 _ l...... N?Z;,0S2a5mfi)Asxc‘>itga:ggn3235 2 rangle, elevation 355 m (1,040 11,900 ft) west of the north- ft). ecast corner sf th? Blalck Star anyon quadrangle, elevation 325 m (1,070 ft). EOCENE F86 18983 .: Between Gypsum Canyon and SANTIAGO FORMATION Coal Canyon, 1,110 m (3,650 ft) south and 6,460 m (21,200 | prgga S97 J. E. Schoellhamer On Santa Ana Canyon Road, 10 m ft) west of the northeast corner and C. H. Gray 25 ft) south and 3,300 m of the Black Star Canyon quad- 10,825 ft) west of the north- rangle, elevation 300 m (980 east corner of the Black Star ft). Canyon quadrangle, elevation F87 BT& 3 Sol do... Near head of Fremont Canyon, 160 m (520 ft). 4,390 m $4,400 ft) south and | rogb $394 J. E. Schoellhamer....... Northeast of Elsinore fault, 625 m 2,500 m (8,200 ft) west of the 2,050 ft) south and 640 m northeast corner of the Black 2,100 ft) west of the northeast Star Canyon quadrangle, eleva- corner of the Black Star Canyon tion 745 m (2,440 ft). uadrangle, elevation 245 m F88 18984 S424 o Llc ... Near head of Gypsum Canyon, 800 ft). 4,640 m (15,225 ft) south and | F19Q - 18993 §§4%/ / HO eves Near head of Gypsum Canyon, 8,000 m (26,250 ft) west of the 4,405 m (14,450 ft) south and northeast corner of the Black 7,880 m (25,850 ft) west of the Star Canyon quadrangle, eleva- northeast corner of the Black tion 265 m (870 ft). Star Canyon quadrangle, eleva- F89 18985 BBA Conc ll Ose dienes Near divide between Gypsum tion 270 m (880 ft). Canyon and Fremont Canyon, | F101 18994 J. G. Vedder Near divide between Gypsum 5,580 m (18,300 ft) south and Canyon and Fremont Canyon, 7,345 m (24,100 ft) west of the 5,965 m (19,575 ft) south and northeast corner of the Black 7,360 m (24,150 ft) west of the Star Canyon quadrangle, eleva- northeast corner of the Black tion 455 m (1,500 ft). Star Canyon quadrangle, eleva- Foo _ 18986 __ S44 ... Near divide between Gypsum s 19: Canyon and Blind Canyon, | F102 ............ Between Weir Canyon and Blind 5,700 m (19,000 ft) south and 7,925 m (26,000 ft) west of the northeast corner of the Black Star Canyon quadrangle, eleva- tion 410 m (1,350 ft). College Canyon, 7,480 m (24,550 ft) locality south and 10,500 m (34,450 ft) 159 west of the northeast corner of the Black Star Canyon quad- ra)ngle, elevation 355 m (1,165 ft). D104 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this - U.S. Geo- in this U.S. Geo- report - logical report - logical Survey No. Survey No. F103 - 18995 D. MEKinney. Near divsd; betweeéx Blind $5125; EOCENE(?) TO MIOCENE J. E. Schoellhamer, yon and Fremont Canyon, 7, i s i 4 4 s 8 and W. P. Woodring m (34.100 ft) s>0uth and t1385 SESPE AND VAQUEROS FORMATIONS, m (24,225 ft) west of the ‘ 4 ‘ northeast corner of the Black UNDIFFERENTIATED Star Canyon quadrangle, eleva- tion 515 m (1,690 ft). F115 D. M. Kinney and Between Santiago Creek and F104 _ 18996 3. G Near divide between Blind Can- J. E. Schoellhamer. “1871383 fgasréimangfigo 4 yon( s maith ami ant solo 58,500 ft) west of the northeast m (28,850 ft) south and 8,610 o of ths Orange quan. m (28,250 ft) west of the a mnole. Bieven 215g q(700 northeast corner of the Black {SHE e, & ion m Star Canyon quadrangle, eleva- - tion 285 m (940 ft). F116 _ 18450 d: Vedder ............. Beéween Weir Canyorz and Blim; F105 18997 Near divide between Blind Can- Elmo“, 6,780 m (22,250 ft th and 9,775 m (32,075 ft yon and Fremont Canyon, 8,915 sou > $ m (3962220mfsf’uth and £530 31853512 ztesrzgitl-Acezzty chrzflrag‘f m (28, t) west o e e northeast corner of the Black £Sngle, elevation 370 m (1,220 Star Canyon quadrangle, eleva- a tion 300 m (980 ft). F117 18480 ten onne de dorcel lee? Between IrviXfie Lake and Santiago F106 16424 __ A. O. Woodford On north shore of Irvine Lake, Canyon Road, 10,365 m 10,805 m (35,450 ft) south and 8543928 $2) 83122: filfldtflg‘igifllf onn comer on Suit easfacorner of the Black Star northeast corner of the Black C a 4 (evan Star Canyon quadrangle, eleva- 35361310? lqixsao 2.ng e, elevation tion 245 m (800 ft). m (1.1 # f F107 _ 18998 D. M. Kinney ............. Between Peters Canyon Wash and | FMS - 18447 =_ = ___ --.-.....--- Beézielz’irvflfieolgfldke 31113 2215131853 Little Joatfluin Valley, 13,855 m 34 ¥OO IA soul 9.670 m gi‘ggofnggrg} fhldnt‘rztigars? 231,725 ftg w?sthofé{1e lilosrth. 4 z east corner of the Black Star ren deveconce nock ay Canyon quadrangle, elevation rangle, elevation 90 m (295 ft). so rty. F108 ._ 18998 | -~ 0 ( In Peters Canyon Wash 13,535 m | F119 _ 18461 D. M. Kinney, Between Irvine Park and Santiago (np a weston fie mor ineadt J. E. Schoellhamer, ___ Canyon Road, 10,395 m 5,600 ft) west of the northeast and W. P. Woodring. £34,100 ft) south and 10,605 m corner of the Orange quad- 34,800 ft) west of the north- rangle, elevation 80 m (270 ft). east corner of the BlackStar 10919060. arm SPAD. doses In Peters Canyon Wash 13,365 m Canyon quadrangle, elevation C 243,850 ft) south and 1,755 m 280 m (920 ft). 5,750 ft) west of the northeast F120 D. M. Kinney ............. Between Irvine Park and Santiago corner of the Orange quad- Canyon Road, 10.440 m rangle, elevation 85 m (275 ft). §34 258 fffl) south 'and 10.470 m 10. . loc Between Little Joaquin Valley and 34,350 ft) west of the north 4 Rattlesnake Canyon Wash, 975 east corner sf thT Blalck Star m (3,200 ft) south and 60 m Canyon qua ra)ng e, elevation (200 ft) west of the northeast 315 m (1,040 ft). corner of the Tustin avad, | Fiz! 18462 _ Ks D. M. Kinney, Between Irvine Park and Santiago rangle, elevation 130 m (420 J. E. Schoellhamer, Canyon Road, 10,485 _ m ft). and W. P. Woodring. _ (34.400 ft) south and 10.485 m : calles one Frie to el Le" Between Little Joaquin Valley and 34,400 ft) west of the north- 5A Rattlesnake Canyon Wash, 330 East corner gf th? Blalck ital» m (1,075 ft) south and 11,200 anyon qua )rang e, elevation m (36,750 ft) west of the 300 m (980 ft). northeast corner of the El Toro | F122 - 18477 =_ K6 _ .._... 40x .a.... On Santiago Canyon Road near uadrangle, elevation 185 m BM 791. 10.685 m (35,050 ft 600 ft). south and 11.185 m (36,700 ft 119. . Dre UBC LLY . 0 Col do.... Xcite. Between Little Joaquin Valley and west of the northeast corner of F Rattlesnake Canyon Wash, 60 the Il?vlackl Star Carly5on qzjad- m (200 ft) south and 11,170 m ra)ng e, elevation 2 m (800 (36,650 ft) west of the north- ft). east corner of the El Toro quad- F123 - 18457 ... On Santiago Canyon Road near rangle, elevation 225 m (730 BM 791. 10.125 m (33.225 ft) fo. south and 11.215 m (36.800 ft) F113 Pomona _ J. G. Vedder .__..........- Between Weir Canyon and Blind west of the northeast corner of College Canyon, 7,270 m (23,850 ft) the lilac]; Satay 082?an (1217850 locality south and 10,865 m (35,650 ft) wing e, elevation m 159a. west of the northeast corner of ft). the Black Star Canyon quad- | F124 | 18472 | -- = = ss. Near intersection of Santiago rangle, elevation 245 m (800 Canyon Road and Peters Can- ft). yon Road; 9.830 m (32,250 10 F114 _ 16967 V97 plus J. G. Vedder and Between Irvine Park and Irvine and 11,490 m (37,700 ft) west locglity W. P. Woodring. Lake, 9,725 m (31,900 ft) gfl thesnorflcxeast come; of tlhe 12 from south and 9,815 m (32,200 ft) 1ac Star any(on qufa) rangle, U.S.G.S. west of the southeast corner of elevation 215 m (700 ft). Prelim. the Black Star Canyon quad- | F125 | 18455 | -- = = ss Near intersection of Santiago Chart 12, rangle, elevation 305 m (1,000 Canyon Road and Peters Can- 1945. ft). yon }1;t)ad(i 9,980 m (82,750 gt; Fil4a 19002 I: G. reece. Near Rattlesnake Canyon, 1,995 south and 11,245 m (36,900 ft s m (6,550 ft) south and 10,640 watBolf tllzesnorthceast corner gf m (34,900 ft) west of the the acl tar 211330n qzlyod northeast corner of the El Toro rangle, elevation m guadrangle, elevation 170 m ft). 560 ft). F126-- 18454 __ --< 5 OOo Ore ee ote Between IEVine Lake and Lime- , 900 stone anyon, 11,950 m oat Nomic chor Ne“5.§§3“§§“§§§£ "52d. 0.840 m $9,200 it; South and 6,890 m 232,275 ft) west of the north- 22,600 ft) west of the north- east corner of the El Toro quad- ra)ngle, elevation 185 m (600 ft). east corner of the Black Star Canyon quadrangle, elevation 355 m (1,160 ft). GEOLOGY OF THE SANTA ANA MOUNTAINS D105 No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this U.S. Geo- in this U.S. Geo- report - logical report - logical Survey No. Survey No. FI2T-38445. ° :e 0 | .....ll.ll.. do .. .... Near south shore of Irvine Lake, 12,055 m (39,550 ft) south and MIOCENE 8,475 m (27.800 ft) west of the TOPANGA FORMATION northeast corner of the Black 5 Star Canyon quadrangle, eleva- tion 300 m (980 ft). F141 S14 F. R.G%odbni1l and Roaaxdcuzz on 50th sige ofOSanta F128 - 18452 D. M. Kinney ............. Between Peters Canyon Reservoir J. E. Schoellhamer. Ana Canyon Road, 1,005 m and Santiago Canyon Road, $3,300 ft) south and 8,610 m 10,340 m (33,925 ft) south and 28,250 ft) west of the north- 365 m (1,200 ft) west of the east corner of the Black Star northeast corner of the Orange Canyon quadrangle, elevation uadrangle, elevation 180 m 120 m (400 ft). 590 ft). F142 _ 18473 815 J. E. Schoellhamer....... Near %anta( A163 Cfaglyon Isaadd, Fi TEAL Neri 0 lie r Between Peters C d San- 1,530 m (5,025 ft) south an By C lk Sego Cangon head, 16.790 an 8.815 m (28,925 ft) west of the 35,400 fall) south and 350 m northeast corner of the Black £1,150 ft) west of the northeast Star Canyon quadrangle, eleva- corner of the Orange quad- tion 185 m (600 ft). rangle, elevation 215 m (700 F143 D. M. Kinney and On divide between Weir Canyon ft). J. E. Schoellhamer. and Santfa Ana fiiverli 3,330 m F180} i 0 .O Mt 8 cise. t P Height d 10,925 ft) south and 9,325 m $ £ "Took thvon Alito |. (29208 & hor me mon 36,650 ft) south and 3,345 m east corner of the Black Star 510,975 ft; west of the north- Canyon quadrangle, elevation east corner of the Orange quad- 365 m (1,200 ft). rangle, elevation 120 m (400 | r144 _ 18443 D. M. Kinney ............. Near head of Weir Canyon, 4,235 ft). m (13,900 ft) south and 9,265 F131 D. M. Kinney and Between Panorama Heights and m (30,400 ft) west of the J. E. Schoellhamer. Peters Canyon, 11,550 m northeast corner of the Black $37,900 ft) south and 2,860 m Star Canyon quadrangle, eleva- 9,375 ft) west of the northeast tion 340 m (1,120 ft). corner of the Orange quad- | F145 18439 D. M. Kinney and Near head of Weir Canyon, 4,395 rangle, elevation 185 m (610 J. E. Schoellhamer. m (14,425 ft) south and 9,975 ft). m (32,725 ft) west of the F132 18446 D. M. Kinney ............. Between Lemon Heights and Red northeast corner of the Black Hill, 13.715 m (45,000 ft Star Canyon quadrangle, eleva- south and 2,985 m (9,800 ft tion 280 m (920 ft). west of the northeast corner of F146 D. M. Kinney ............. Near head of Weir Canyon, 4,535 the Orange quadrangle, eleva- m (14,875 ft) south and 10,410 tion 90 m (290 ft). m (34,150 ft) west of the F133 18469 K5 D. M. Kinney, Near Limestone Canyon, 60 m northeast corner of the Black J. E. Schoellhamer, $200 ft) south and 6,685 m Star Canyon quadrangle, eleva- and W. P. Woodring. 21,925 ft) west of the north- tion 300 m (980 ft). east corner of the El Toro quad: F147 - 18474 D. M. Kinney, Near divide between Gypsum rangle, elevation 340 m (1,120 J. E. Schoellhamer, Canyon and Blind Canyon, ft). and J. G. Vedder. 4,955 m (16,250 ft) south and F134 _ 18471 A. AIAN ...... Near Limestone Canyon, 115 m 8,290 m (27,200 ft) west of the 375 ft) south and 6,600 m northeast corner of the Black £21,650 ft) west of the north- Star Canyon quadrangle, eleva- east corner of the El Toro quad- tion 435 m (1420 ft). rangle, elevation 300 m (980 | pr14s 18442 JAG. Near head of Weir Canyon, 4,905 ft). m (16,100 ft) south and 9,705 F135 - 18470 D. M Kinney .............. Near Limestone Canyon and m (31,850 ft) west of the Rattlesnake Canyon, 275 m northeast corner of the Black 2900 ft) south and 8,855 m Star Canyon quadrangle, eleva- 29,050 ft) west of the north- tion 335 m (1,100 ft). east corner of the El Toro quad- F149 _ 18463 A. E. Altinli and Near head of Weir Canyon, 5,050 rangle, elevation 285 m (940 J. G. Vedder. m (16,625 ft) south and 9,855 ft). m (32,325 ft) west of the F186 38458 .. =~ l Cl... do.. Accs.: Between Rattlesnake Canyon and northeast corner of the Black Limestone Canyon, 175 m (575 Star Canyon quadrangle, eleva- it; south and 10,325 m (33,875 tion 340 m (1,120 ft). ft) west of the northeast corner | p15Q _ 18467 J.G. Vedder .............. Near head of Weir Canyon, 5,165 of the El Toro quadrangle, ele m (16,950 ft) south and 9,190 vation 280 m (920 ft). m (30,150 ft) west of the FAB: (in lon ien ( 00 Co Between Rattlesnake Canyon and northeast corner of the Black Limestone Canyon, 290 m (950 Star Canyon quadrangle, eleva- fig south and 10,335 m (33,900 tion 445 m (1,460 ft). ft) west of the northeast corner |_ p151 _ 18466 A.E.Altinli ..._...........; Between Walnut Canyon and Weir of the El Toro quadrangle, ele- 53 Canyon, 5,625 m (18,450 ft) vation 265 m (870 ft). south and 120 m (400 ft) west F138 f19 Pomona College Between Round Canyon and Agua of the northeast corner of the Field geology Chinon Wash, 3,995 m (13,100 Orange quadrangle, elevation class, 1953. ft) south and 5,500 m (18,050 270 m (800 ft). ft) west of the northeast corner F152 - D. M. Kinney ............. Between Walnut Canyon and San- of the El Toro quadrangle, ele- tiago Creek, 5,105 m (16,750 vation 375 m (1,230 ft). f) south and 1.528 m (5,000 F139 Y28a R.F:¥erkes.:..........«c. Between The Sinks and Santiago ft) west of the northeast corner Creek, 4,055 m (13,300 ft of the Orange quadrangle, ele- south and 2,805 m (9,200 ft vation 260 m (850 ft). west of the northeast corner of | p153 _ 18438 nese Between Walnut Canyon and San- the El Toro quadrangle, eleva- ' tiago Creek, 5,050 m (16,575 tion 480 m (1,570 ft). ft) south and 1,645 m (5,400 F140 NBd | Oi Between Panorama Heights and ft) west of the northeast corner Peters Canyon, 11.415 m of the Orange quadrangle, ele- £37,450 ft) south and 2,090 m vation 255 m (830 ft). 6,850 ft) west of the northeast F154 _ 18444 W. P. Woodring .......... Between Walnut Canyon and San- corner of the Orange quad- tiago Creek, 4,925 m (16,150 rangle, elevation 190 m (620 ft; south and 3.115 m (10,225 ft). ft) west of the northeast corner vi Cal. Tech. William Otto, Near Bolero Lookout, 5,030 m of the Owns? lg‘baggansle, ele- loc. J. E. Schoellhamer, $16,500 ft) south and 2,820 m vation 255 m (830 ft). v499 and J. G. Vedder. 9,250 ft) west of the northeast F155 _ 18468 d:P Nedder:.,;....c...... Between Walnut Canyon and San- $360 corner of the El Toro quad- tiago Creek, 5,020 m (16,475 angle. elevation 425 m (1,400 t). ft; south and 3,130 m (10,275 ft) west of the northeast corner D106 GEOLOGY OF THE EASTERN LOS ANGELES BASIN, SOUTHERN CALIFORNIA No. usedPermanent Field No. Collected by- Description of locality No. usedPermanent Field No. Collected by- Description of locality in this - U.S. Geo- in this - U.S. Geo- report - logical report - logical Survey No. Survey No. F155-Continued of the Orange quadrangle, ele- F171 128 do Between Li t Canyon and vation 220 m (720 ft). Bee Canyon, 2,135 m (7,000 ft) F156 - 18449 .. Between Walnut Canyon and San- attthogligefsfllotghglasazgérlsgr if} tiago Creek, 5,165 m 516.950 the El Toro quadrangle, cleva- ft) south and 3,180 m (10,425 fin 410 m (roid n. * ft) west of the northeast corner ton f of the Orange quadrangle, ele- F172 $250 J. E. Schoellhamer....... Near head of Round Canyon, vation 200 m (650 ft). 3,985 m (13,075 ft) south and F157 - 18441 s¢ Betweenyalrlzutngéxgvon “1178536 [5161325155 £1312? Sf) 312850 {F313 tiago Creek, 5, m f 7 ft) south and 3.400 m (110g =_ "ante 45008 ft) west of the northeast corner » + of the Orange quadrangle, ele- F173 Y27a R.T.Nerkes..s........... Near Bolero Lookout, 4,955 m vation 195 m (640 ft). 216,250 fig south 1nd 3,450 m F158 - 18478 D. M. Kinney ............. Between Walnut Canyon and San- eislgiiini', o‘zetite (£51 {isle-02133: tiago Creek, 5,250 m 517225 rangle, elevation 465 m (1,520 ftg south and 3,675 m (12,050 ft). ft) west of the northeast corner of the Orange quadrangle, ele- vation 195 m (640 ft). PLIOCENE F159 D. M. Kinney, Between Cerro Villa Heights and J. (115 Schowhamer, Santiago , Creek, 5,730 m FERNANDO FORMATION and W. P. Woodring. £18,800 ft) south and 5,120 m 16,800 ft) west of the north- LOWER MEMBER east corner of the Orange quad- rangle, elevation 135 m (450 | pr174 D. M. Kinney ............. Near Peralta Hills, 2,820 m ft). 9,250 ft) south and 5,260 m F160 McKee Oil Co. well Kokx Com- 17,250 ft) west of the north- munity 8-1, ditch sample from east corner of the Orange quad- depth of 1.040 to 1,060 m rangle, elevation 110 m (360 3,410 to 3,475 ft) 5,725 m ft). 18,775 ft) south and 7,390 m | F175 R202 J. F. Richmond ... B Poi 24,250 ft; west of the north- cs. soo" N91113vggoraltlelsouggnatfidAéfiiéo $1!) east corner of the Orange quad- 516,600 ft; west of the north- rangle. east corner of the Orange quad- F161 D.M. Kinney ............; In roadcut on Irvine Park Drive rangle, elevation 265 m (870 near]; intersecgon with gésnge ft). Park Acres Drive, 8, m | F176 R253 D. M. Kinney, Near Burruel Point, 4,495 m 529,500 ftg south and 3,125 m J. F. Richmond, 514,750 ft) south and 5,820 m 10,250 ft) west of the north- A. 0. Woodford, and 19,100 ft) west of the north- east corner of the Orange quad- W. P. Woodring. east corner of the Orange quad- £Snglev elevation 185 m (600 ra)ngle. elevation 200 m (650 > ft). F162 D. M. Kinney and Between Panorama Heights and | F177 R242 J. F. Rich Well N B 1 Point, 4,34 J. E. Schoellhamer. Peters Canyon, 10,975 m Munck 311‘25ugwfsouffinand (£3855 E £36,000 ft) south and 2,300 m 20,950 ft) west of the north- 7,550 ft) west of the northeast east corner of the Orange quad- corner of the Orange quad- rangle, elevation 220 m (725 fingle, elevation 200 m (650 ft). t). F178 B241 ! E. sc Gls cll. eds N B 1 Point, 4, F163 Pomona _ A. 0. Woodford and Near Pomona Heights, 11,055 m | ealg,72u5"f‘€)esougtlxnand 6759555 2 College _ Pamona College £36,275 ft) south and 3,960 m §21y500 ft) west of the north- locality _ geology students. 13,000 ft) west of the north- east corner of the Orange quad- 47 east corner of the Orange quad- rangle, elevation 175 m (570 fingle, elevation 150 m (495 ft). t). F164 Pomona _ Frank Rentchler......_... On Red Hill, 45 m (150 ft) south College and 3,680 m (12,075 ft) west of MICROFOSSIL LOCALITIES locality the northeast corner of the Tus- 2509 §in qua)drangle, elevation 85 m MIOCENE 280 ft). F165 D. M. Kinney ............. Between Santiago Canyon Road TOPANGA FORMATION and Irvine Park, 9,220 m - 530,250 ft) south and 455 m | No. __ No. usedPerma- _ Field 1,500 ft) west of the northeast | used _ in U.S. nent No. corner of the Orange qzxad- "l: freo- j g-SA rangle, elevation 215 m (710 | this ogical eo- eas i ft). report - Survey logical Coileited Description of locality F166 A. E. Altinli and Between Irvine Lake and Santiago Prof -_ * J. G. Vedder. Canyon Road, 10,920 m Paper - No. 535.825 ft; south and 9,920 m R 294 -M 10 west of Te {osrth- m179 - ml £11413 Y8b D. M. Kinney and Between Panorama Heights and east corner of the Black Star Canyon quadrangle, elevation R. F. Yerkes. Peters Canyon, 11,185 m f h and 1,915 m 370 m (1,220 ft). £36,700 ft) sout B e 6,275 ft) west of the northeast F167 18476 . Near south shore of Irvine Lake, corner of the Orange quad- 12,175 m (39,950 ft) south and rangle, elevation 215 m (710 8,810 m (28,900 mfwist lg] mi ft). ggxhé::;ozof]3ifirznélé 61:1; m180 _ m2 £11414 D. M. Kinney........... Between Panorama Heéghts and tion 345 m (1,140 ft). Peters Canyon, 10,850 m ; 35,600 ft) south and 2,150 m F168 18440 SA152 J. G. Vedder ...... ... Near south shore of Irvine Lake, 7,050 ft) west of the northeast 12,285 m (40,300 ft) south and corner of the Orange quad- 8,810 m (28,000 ft) west of the rangle, elevation 220 m (720 southeast corner of the Bllack ft). Star Canyon quadrangle, eleva- m181 _ m3 £11415 do Between Walnut Can fon 345 m (1.140 80." - ~- J anl81- moo ~ f1l416 olen yon and tion 345 m (1,140 ft). Cerro Villa Heights, 5,275 m F169 _ 18456 A. E. Altinli ... ... Near south shore of Irvine Lake, 217.300 ftg south and 3,640 m 12,255 m (40,200 ft) south and 11,950 ft) west of the north- 8,685 m (28,500 ft) west of the east corner of the Orange quad- northeast corner of the Black rangle, elevation 190 m (620 Star Canyon quadrangle, eleva- ft). ia (M0401: m182 | m4 -_ f11416 McKee Oil co. well Kokx Com- F170 127 Pomona College Between Limestone Canyon and munity 8-1, core sample from field geology class, 1953. Bee Canyon, 2,025 m (6,650 ft) south and 5,640 m (18,500 ft) west of the northeast corner of the El Toro quadrangle, eleva- tion 425 m (1,400 ft). 717 and 719 m (2,354 and 2,360 ft) 5,725 m (18,775 ft) south and 7,695 m (25,250 ft) west of the northeast corner of the Orange quadrangle. GEOLOGY OF THE SANTA ANA MOUNTAINS D107 No. No. usedPerma- _ Field No. No. usedPerma- _ Field used _ in U.S. nent No. used _ in U.S. nent No. in eo- _ U.S. in Geo- U.S. this logical Geo- age ; this logical Geo- Unie i report Sflrvey logical Collected Description of locality report Sugrvey logical Coilected Description of locality Prof. _ Survey by- Prof. _ Survey Y~ Paper No. Paper No. 204 -M 294 -M m195-Continued rangle, elevation 220 m (720 EL MODENO VOLCANICS ft). m196 _ m7 £11419 _ $344 J. E. Schoellhamer Roadcut near La Paloma, 10,755 m (35,350 ft) south and 5,000 m183 - ms f11417 _ Y6a R.F. Yerkes .._______.. Near divide between Walnut Can- m (16,400 ft) west of the on and Weir Canyon, 5,355 m northeast corner of the Orange {17.575 ft) south and 290 m uadrangle, elevation 90 m 950 ft) west came northeast 2290 ft). corner of the Orange q4@d~ | m1g7 | mg £11420 Roadcut on Mesa Drive near Fangle, elevation 345 m (1,130 Cerro Villa Heights, 5,545 m £ $8,200 ft; south and 5,660 m 18,575 ft) west of the north- east corner of the Orange quad- MONTEREY SHALE fingle, elevation 135 m (440 t). r MIY7® Ba cece 0200 00 +h golly CO Between Burruel Point and Cerro m184 - m18 _ £11430 _ $259a J. E. Schoellhamer - Ditch on south side of the Lam- Villa Heights, 5,350 m 517550 bert Reservoir, 6.385 m ft; south and 6,235 m (20,450 20,950 ft) south and 8,000 m ft) west of the northeast corner 26,250 ft) west of the north- of the Orange quadrangle, ele- east corner of the El Toro quad- vation 120 m (400 ft). rangle, elevation 145 m (470 | m199 - m10 £11422 Y5d D. M. Kinney, Near Peters Canyon Reservoir, ft). J. E. Schoellhamer 10,560 m (34,650 ft) south and m185 | m19 _ f11481 _ $259...._______. dd Same locality as m184; about 5 m and R. F. Yerkes. 580 m (1,900 ft) west of the (20 ft) higher stratigraphically. northeast corner of the Orange uadrangle, elevation 190 m 620 ft). PUENTE FORMATION m200 m1il _ f11423 _ S67 J. E. Schoellhamer.... Old roadcut above Santa Ana Canyon Road and west of Gyp- sum Canyon, 1,015 m (3,325 m186 _ m20 £11432 __ Y78a J. E. Schoellhamer Near head of Serrano Creek, ft) south and 9,450 m (31,000 and R. F. Yerkes. 6,605 m $21,675 ft) south and ft) west of the northeast corner 1,690 m (5,550 ft) west of the of the Black Star Canyon quad- northeast corner of the El Toro rangle, elevation 185 m (600 uadrangle, elevation 440 m ft). 1,450 ft). m201 - m12 11484 o ( C Roadcut near south shore of Ir- m187 _ m21 {11438 - Y78b............ C0 Near head of Serrano Creek, vine Lake, 11,965 m (39,250 ft; 6,670 m 521,875 ft) south and south and 9,205 m (30,200 ft 1,685 m (5,525 ft) west of the west of the northeast corner of northeast corner of the El Toro the Black Star Canyon quad- uadrangle, elevation 435 m rangle, elevation 250 m (820 1,420 ft). ft). m188 _ m22 £11494 ¥78¢.......... CG seo ick ice Near head of Serrano Creek, | m202 m14 £11426 - 8236........... NQ «receno dues Near divide between Peters Can- 6,690 m 521,950 ft) south and yon and Santiago Canyon Road, 1,685 m (5,525 ft) west of the 12,375 m (40,600 ft) south and northeast corner of the El Toro 11,245 m (36,900 ft) west of uadrangle, elevation 430 m the northeast corner of the ?1.410 he. Black Star Canyon quadrangle, m189 | m@B | £11485 | Y79e............ brs ona. Near head of Borrego Canyon, elevation 355 m (1,160 ft). 5,945 m (19,500 ft) south and | m204 - m17 f11430 (BBS ............ dO eecsscl.ss Between Burruel Point and Cerro 3,230 m (10,600 ft) west of the Villa Heights, 5,030 m (16,500 northeast corner of the El Toro ft) south and 5,915 m (19,400 uadrangle, elevation 345 m ft) west of the northeast corner 1,140 ft). of the Orange quadrangle, ele- m190 | m24 | £11436 - Y78d....._____.. dS e-- Near head of Serrano Creek, vation 170 m (560 ft). 6,715 m $22,025 ft) south and | m205 - m16 _ £11428 _ S2 ..._________ H0 Near Santa Ana Canyon Road 1,705 m (5,600 ft) west of the west of Gypsum Canyon, 1,280 northeast corner of the El Toro m (4,200 ft) south and 9,905 m uadrangle, elevation 425 m (32,500 ft) west of the north- 1,400 ft). East corner Elf the Blalck Star miQ1 m95 - f1148? | Y¥79di........000 Cb ...... Near head of Borrego Canyon, anyon, quadrangle, elevation 5,990 m (19,650 ft) south and 200 m (660 ft). 3,230 m (10,600 ft) west of the northeast corn? of the El Toro 11,1411??? .le, elevation 360 m PLIOCENE m192 - m26 £11438 do LEC Near head (of Bongo Cagyon, FERNADO FORMATION 6,020 m (19,750 ft) south and 3,260 m (10,700 ft) west of the LOWER MEMBER northeast corner of the El Toro uadrangle, elevation 365 m 1,200 ft). m206 £11469 D. M. Kinney........... Near Burruel Point, 4,730 m m193 - m27 £11499 _ ~¥79b............ 06 sc Near head of Borrego Canyon, 515,500 fig south and 6,875 m 6,050 m (19,850 ft) south and 22,550 ft) west of the north- 3,290 m (10,800 ft) west of the east corner of the Orange quad- northeast corner of the El Toro rangle, elevation 170 m (560 uadrangle, elevation 370 m ft). i210 ft}: m207 £11470 _ $271J.E. Schoellhamer _ Near Burruel Point, 4,730 m m194 - m28 _ f1144 .:.. do........... Near head of Serrano Creek, and R. F. Yerkes. 515,500 ft) south and 7,125 m 6,865 m $2,525 ft) south and 23,375 ft) west of the north- 1,705 m (5,600 ft) west of the east corner of the Orange quad- northeast corner of the El Toro rangle, elevation 160 m (530 uadrangle, elevation 400 m ft). 1,320 ft). m208 $377 D. L Durham and Northwest of the Kraemer oil m195 _ m6 £11418 Y5e R.F. Yerkes............ Near Santiago Canyon Road and J. E. Schoellhamer. field, 140 m (450 ft) south and BM 791, 10,835 m (35,550 ft; south and 11,430 m (37,500 ft west of the northeast corner of the Black Star Canyon quad- 3,035 m (9,950 ft) west of the northeast corner of the Orange uadrangle, elevation 140 m 460 ft). INDEX [Note: Lists of names and localities in section "Supplemental Information" have not been indexed. Italic page numbers indicate major references.] Agua Chinon Wash, 41, 42, 44, 47, 52, 58 Alisitos Formation, 11 Aliso Creek, 21, 22, 41, 53 Alluvial deposits, 60 Alteration, 10 Anaheim nose, 39, 66, 67 Baker Canyon, 11, 13, 14, 18, 19, 22, 23, 24 Baker Canyon Conglomerate, 18 Baker Canyon Conglomerate Member, 11, 12, 13, 15, 63 Bedford Canyon, 3 Bedford Canyon Formation, 3, 6, 8, 9, 10, 11, 12, 21, 22, 23, 30, 43, 62, 63, 66 Bee Canyon, 21, 41, 42, 43, 47, 52, 58, 64, 65, 66 Black Star Canyon, 6, 11, 12, 13, 14, 15, 17, 18, 20, 22, 26, 27, 28, 65 Black Star Creek, 11 Blind Canyon, 19, 61 Bolero Lookout, 34, 36 Borrego Canyon, 52 Brea Canyon, 58 Burruel Ridge, 32, 34, 36, 38, 40, 42, 44, 47, 48, 49, 50, 51, 53, 54, 56, 60, 65, 66 Cahuenga Pass, 42 Capistrano Formation, 41, 47, 52, 56, 57, 64 Carbon Canyon, 58 Chapman sand, 49, 50 Chico Formation, 11 Chino trough, 63 Claymont Clay Bed, 21, 23, 26, 27 Coal Canyon, 15, 17, 21, 22, 26, 30, 31 Corona trough, 63 Coyote Hills, 39 Cretaceous System, 6, 11, 67 Cristianitos fault, 41 Domengine Formation, 31 Domenguez oil field, 41 East Coyote oil field, 48 El Modeno, 42 El Modeno Volcanics, 37, 39, 46, 57, 60, 64 El Modeno fault, 64, 65 Elsinore fault, 11, 21, 63, 65 Eocene Series, 28, 31, 67 Epidotization, 10 Espada Formation, 11 Eugenia Formation, 11 Faults, 63 Fernando Formation, 51, 53, 59, 65, 66 Folds, 65 Fossils: Amphimorphina californica, 31 Amphistegina californica, 31 Anadara (Larkinia) santana, 36 Atira ornatissimus, 21 Brachysphingus lyratus, 28 Buchia piochii, 11 Calva bowersiana, 21 Cassidulina, 56 Chione temblorensis, 39 Cibicides memastersi, 31 pseudowellerstorffi, 31 Coralliochama, 19 Crassatella lomana, 17 tuscana, 17 Crassostrea titan subtitan, 39 Cucullaea, 13 mathewsonii, 28 gravida zone, 15 Discoaster sublodoensis, 31 Ellipsoglandulina fragilis, 53 Epistominella subperuviana, 56 Eriphyla lepidus, 17 Etea angulata, 17 Gaudryina (Pseudogaudryina) coalingensis alata, 31 Glycymeris pacificus zone, 15 veatchii zone, 16, 19, 21 Fossils-Continued Gyroidina simiensis, 31 Haplophragmoides nonionelloides, 31 Kewia fairbanksi santanensis, 36 Legumen ooides, 21 Lembulus striatula, 21 Leptopecten andersoni, 39 discus, 46 Massilina decorata, 31 Meekia, 21 Megapetalus lovenioides, 53 Metaplacenticeras pacificum, 21 Opis, 19 Parallelodon vancouverensis, 17 Paratylopus primaevus, 36 Perissolax tricarnatus, 26 Pterotrigonia, 13 Rapana vaquerosensis imperialis, 34, 36 Spondylus, 13 Subprionocyclus, 15 Terebra santana, 36 Thyasira gouldii, 56 Trajanella, 19 Trigonarca, 13 Trigonarca californica zone, 15 Turritella chicoensis, 16, 19 chicoensis chicoensis, 17 chicoensis perrini, 16, 17 inezana santana, 32, 34 ocoyana, 37 ocoyana topangensis, 39 pachecoensis, 26, 27, 28 temblorensis, 39 Uvigerina peregrina, 56 Vertipecten nevadanus, 39 Fremont Canyon, 16, 17, 18, 19, 21, 22, 26, 28, 61, 63, 65 Fresno Canyon, 15, 27, 32, Gypsum Canyon, 19, 21, 22, 27, 30, 31, 34, 37, 38 Hagador Canyon, 11 Hall Canyon, 14, 61 Harding Canyon, 11 Holocene Series, 60 Holz Ranch, 15 Holz Shale Member, 12, 13, 14, 15, 17, 21, 58, 63, 65 Inglewood oil field, 41 Introduction, 1 Irvine Lake, 15, 17, 18, 20, 26, 28, 38, 42, 65 Irvine Park, 14, 17, 19, 20, 21, 22, 26, 28, 39, 65 Jurassic System, 3, 6, 67 Kraemer oil field, 40, 50, 51, 52, 53, 54, 65, 6 Kraemer zone, 48 La Habra Conglomerate, 58 La Habra Formation, 57, 58, 66 La Jolla Group, 31 La Vida Member, 40, 42, 47, 53, 57, 60, 62, 64, 65 La Vida Member, 57 Ladd Canyon, 3, 8, 12, 14, 15, 61 Ladd Formation, 11, 12, 58, 63, 65 Lambert Reservoir, 41, 58, 64 Leffingwell oil field, 36 Limestone Canyon, 32, 34, 43, 46, 48, 61, 64 Little Joaquin Valley, 11, 14, 43, 64, 65 Llajas Formation, 31 Loma Ridge, 34, 37, 42, 43, 46, 47, 48, 60, 61, 62, 64, 65 Long Beach oil field, 56 Mabey Canyon, 11 Martinez Formation, 21 Metamorphism, 10 Miocene Series, 31, 37, 42, 52, 67 Monterey Shale, 41, 42, 47, 52, 57, 58 Niguel Formation, 41, 53, 57 Oak Flat, 3, 14, 17 Oligocene Series, 67 Olive oil field, 40, 51, 64, 65, 6 Oso Creek, 41, 42, 52 Oso Member, 47, 52, 64 Paleocene Series, 21, 67 Palos Verdes Hills, 41, 56 Panorama Heights, 40 Peninsular Ranges, 67 Peralta Hills, 51, 65 Peters Canyon, 32, 33, 39, 46, 64, 65 Peters Canyon Reservoir, 42 Pleasants Sandstone Member, 19, 21, 22 Pleistocene Series, 58, 60 Pliocene Series, 52, 53 Puente Formation, 36, 37, 39, 40, 41, 42, 46, 47, 48, 57, 59, 60, 61, 62, 63, 64, 65, 66 Puente Hills, 37, 41, 42, 58, 62, 63, 67 Quaternary System, 58 Rattlesnake Canyon, 21, 34, 43, 64 Red Hill, 38 Regional interpretations, 67 Repetto Formation, 56 Repetto Hills, 56 Richfield oil field, 46, 48, 49, 50, 51, 52, 66 Round Canyon, 42, 43, 47, 58, 61 San Joaquin Hills, 15, 37, 39, 41, 56, 67 San Joaquin Hills area, 63 San Onofre Breccia, 41, 47 Santa Ana Canyon, 13, 14, 17, 31 Santa Ana Mountains, 58, 62, 63, 64 Santa Ana River, 14, 15, 17, 23, 28, 42, 46, 47, 50, 52, 54, 56, 58, 61, 62, 65, 66 Santa Monica Mountains, 41, 42 Santa ¥nez Mountains, 11 Santiago Coal mine, 26 Santiago Creek, 17, 18, 20, 22, 25, 28, 32, 34, 37, 47, 61, 62, 64, 65 Santiago Dam, 18 Santiago Formation, 21, 28, 31, 64, 65 Santiago Peak, 6 Santiago Peak Volcanics, 3, 6, 12, 13, 14, 62, 63, 66 Schulz Ranch Sandstone Member, 17, 19, 21 Serrano Clay Bed, 21, 22, 26, 27 Serrano Creek, 41, 53 Sespe Formation, 28, 31, 37, 41, 43, 46, 57, 58, 60, 64, 66 Sierra Peak, 7, 9, 10, 12, 13 Silverado Canyon, 3, 7, 8, 11, 13, 15, 18, 19, 31, 61 Silverado Formation, 19, 21, 28, 64, 65 Soquel Member, 42, 46, 52, 63, 64 Southern California batholith, 3, 6, 21 Star Quarry, 34, 35 Structure, 62 Summary, 67 Sycamore Canyon Member, 42, 49, 50, 53 Temescal Wash Quartz Latite Porphyry, 9 Terrace deposits, 60 Tertiary System, 21, 67 The Sinks, 32 Tierra colorado, 23 Tomato Spring, 64 Topanga Canyon, 37 Topanga Formation, 36, 37, 41, 46, 57, 60 Tourmalinization, 10 Trabuco Formation, 11 Vaqueros Formation, 28, 31, 37, 41, 43, 46, 57, 58, 60, 64, 66 Walnut Canyon, 47, 48, 59, 51, 52 Wardlow Canyon, 10 Weir Canyon, 32, 34, 37, 38, 40, 43, 46 Whittier fault, 15, 27, 28, 29, 30, 32, 63, 65 Williams Canyon, 8, 11, 14, 15, 17, 19 Williams Formation, 17, 21, 64, 65, 66 Wilmington oil field, 56 Yorba Member, 42, 46, 48, 49, 53, 57 D109 Geology of the Eastern Los Angeles Basin, Southern California GE O LOGICAL SURVEY-PROFESSIONAL PAPER 4 2 0 This volume was published as separate chapters A-D UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS [Letters designate the separately published chapters] (A) Geology of the Los Angeles basin California - an introduction, by R. F. Yerkes, T. H. McCul- loh, J. E. Schoellhamer, and J. G. Vedder. (B) Geology and oil resources of the eastern Puente Hills area, southern California, by D. L. Durham and R. F. Yerkes. (C) Geology and oil resources of the western Puente Hills area, southern California, by R. F. Yerkes. (D) Geology of the northern Santa Ana Mountains, California, by J. E. Schoellhamer, J. G. Ved- der, R. F. Yerkes, and D. M. Kinney. / apo 587-041 UNITED STATES DEPARTMENT OF THE INTERIOR 3 A" 1000 F 1000 1000 -, LOMA RIDGE g § SYNCLINE w | g Kws Landslide ~, Rubicon Oil Co. Texas Co. x g] o Landslide Kih g FEET Wilcox No. 1 8 Irvine (NCT-1) No. 1 g A Texas Co. a if 3 __/ Landslide / E Sf - 2000 s 5 3 Irvine (NCT-2) No. 1 Ola E Irvine Lake :. Kp 7 == & (z § 5 3 Tsa _ /Is 3 - Standard Oil Co. 2 iL £1 500 = a mA 500 ; = | 7 o 500 = | x Yorba Comm. No. 1 Landess Oil Co. 5 | [=) FTemb bef & o js: 0 _ Well No. 1 D Id: 3 I , a s |_'l Qoa Qya Qoa Qya Shell Oil Co. i v2 Tps Tt Tvs Tsa H Tsl Tgiq Qoa Amerada Petroleum Corp. West American Oil Co. S w T n. n e __ roan ..... L ___ L .. ___. Travis No. 1 Santa Ana River | J % f f C § S w | | Q oir Irvine No. 63-1 Irvine No. 1 m Oya Qya Tpse | | me - I i- - SEA LEVEL SEA LEVEL SEA LEVEL SEA LEVEL -;; I 3 | | ? Chapman Qlh(?) § I sand g r ts cn ~~ ee | ‘ - 500 500 o Rocks of unknown age and correlation l t> 2000 ? ? 2-- | | TD 3523" | , e __ . _ g) 1074m Puente Formation | SOC <_ ‘ *" 2 _ e ‘ |- 1000 1000 l I i- 4000 1195m | | 1500 a a < _ _ ___ _i , P |- 1500 1500 l K2 ail ~ | | | - 6000 TD 6158' f | 1877 1928m 2000 f | 2000 2000 W A 2 # METERS METERS METERS 1000 - 1000 1500 T FEET y - 4000 f Texas Co. > i : Irvine (NCT-2) No. 1 2] o|< Tps Q42 _ Landslide, TPIVy, Tps 2 500 -I L 90> w: ie are.. T! 500 1000 - 8 § 9M 5D C & Shoreline Oil Co. ad: 74 z >| g 9, Pinkerton No. 1 g‘ fe Tvs 6 3 212 as: 3 Tt Tvs a |Qva #4 E/Y 58 4 § |- 2000 $x % ~A Smad a l < Tply §| 3 SEA LEVEL ~[<« aie 500 ectore Bee Canyon | 1!" w | ell Oil Co. ; S Shell Oil Co. Shell Oil Co. Irvine Corehole No. 1 $4 | Irvine Corehole No. 5 Irvine Corehole No. 2 ¢ TV ___ nS > E. 500 500 SEA LEVEL -pe- & SEA LEVEL Qth (?) 1000 500 (" 1999 - 2000 TD 3626° 1105m } | | I --- 1500 : | 1500 1000 | | | l, I 1 | - 4000 | | A | | | | | | | | | | I | AE |. _" -- | 2000 I I 2000 1500 Richfield Oil Corp. Peralta Hills No. 1 V M 4 #, U METERS METERS METERS 500 500 1500 S —| Standard Oil Co. McKee Oil Co. A. A. Carrey r x FEET t Taft Comm. No. 1 Kokx Comm. No. 81 Bixby-Nohl No. 1 Standard Oil Co. 2 A e Olive-Orange No. 1 Southeast Richfield Unit No. 1 & ,:| o See plate 1 for explanation of map unit Symbols Tfu Q Qoa C 61 a © LJ ---: f ? _ * A SEA LEVEL -__ ? ? : g, g ~ 7 ri SEA LEVEL 1000 S LITHOLOGIC SYMBOLS s e . 0 , 0 s © ® 4 Ey s 6 5 21 a; 2 go Kih se | |- 2000 2 8:3 ie 4 g Z Complexly | folded Jbe Sandstone a- j o 206 500 500 Shell Oil Co. 243 ." Ths Qya Tvs Tsa 2 Tsi | ; Irvine Corehole No. 2 Oya _ yale s. ae Shell Oil Co A r o | X Tplv Qoa etme ea % | : f (proj. 600° N. 63°W.) % bac Irvine Corehole 5 Oya . | Z a KJsp | norma | | | |- |- sEaA LEvEL 1000 1000 SEA LEVEL | | E 2 | Pebbly sandst 777777777777777 | | | > | 1500 1500 500 | |- 2000 | | | : 1 l > Shale or claystone. - 2000 1000 -| TD 35563 1 m x x xx | - 4000 X KX X X Xx | | | Intrusive igneous rocks | I l (See note on section) | | 2500 2500 1500 22 2 Q 2 AA A A A Andesite flows and flow breccia (See note on section) a ae iof ae 22 ol yest m E3 fa x Slightly metamorphosed siltstone and sandstone Re AB A A D METERS $ ( X aa a 1000 - Shell Oil Co. 53 O a a a D 8 Irvine Corehole 5 K < § Paleonite tuff and tuff- breccia 'R U § o $1 FEET + + + + < S + +>+ % § 2\3 c |- 2000 Y ~ > C S OIF & 500 - & 3 Basalt flows i Fale ; 72 ALE 1:24,000 Shell Oil Co. Shell Oil Co. p a o 1 MILE Irvine Corehole 3 Irvine Corehole 4 Oya z. m- s- -m r ; Qya 1KILOMETER - ":( EVEL 1 .5 0 SEA LEVEL -1:" g 5 SEAL -A- pe --- Qin(?) 500 5 i- 2000 TD 2006" s STRUCTURE SECTIONS G-J , R-S, L-P,U-W, M-F, U-V , T-X NORTHERN SANTA ANA MOUNTAINS, CALIFO 1500 Interior-Geological Survey, Reston, Va.-1981-G79378 9d SL 30