Preliminary Geologic Map available from: STATE OF CALIFORNIA - ARNOLD SCHWARZENEGGER, GOVERNOR CALIFORNIA GEOLOGICAL SURVEY http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm THE RESOURCES AGENCY - MIKE CHRISMAN, SECRETARY FOR RESOURCES JOHN G. PARRISH, Ph.D., STATE GEOLOGIST DEPARTMENT OF CONSERVATION - BRIDGETT LUTHER, DIRECTOR Prepared in cooperation with the U.S. Geological Survey, Southern California Areal Mapping Project 119 o22'30" GEOLOGIC MAP OF THE o 34 30'00" Ku 50 70 o 55 Qw 65 119 15'00" Ku 55 Qls 65 Tj Ku 70 Qha Qls 62 Tj o 52 65 77 75 70 60 66 34 30'00" MATILIJA 7.5' QUADRANGLE 50 72 55 74 48 Qls? Ku 81 60 77 75 57 Qls? 74 55 Tj Qha 74 55 80 Qls 73 62 Qls 82 80 VENTURA COUNTY, CALIFORNIA: A DIGITAL DATABASE Qha 50 70 Tj 52 67 71 Tj 67 Tj 75 54 Qpa Qls 55 87 65 Tj Qls? 87 70 60 Qls Tj 65 Qha 70 55 Qls? 72 Qw VERSION 1.0 62 Tj 72 Tj 70 62 Qls? 62 Tma 62 50 62 Tj Tma 60 Tj Qls 65 66 By 1 Qha 65 Qls? Siang S. Tan 1 Tj Qpa 72 and Terry A. Jones 87 71 Qls? Qls Qpa 80 85 55 60 55 Qls Tcd 72 Digital Database 75 87 88 73 88 Tma 75 Tma 62 by Tj 70 60 2 62 Qls 86 Qls? Carlos I. Gutierrez 70 50 Qls? 66 87 60 Tcd Qls? 87 Qls? 2006 88 Qls 70 Qls? 67 86 75 Tma Qls? Tcd 1. California Geological Survey, 888 South Figueroa Street, Suite 475, Los Angeles, CA 90017 50 67 65 88 82 50 42 Qw 2. California Geological Survey, 801 K Street, MS 12-32, Sacramento, CA 95814 60 35 73 75 74 Qls? 50 65 71 70 Qpa Qls? 73 70 Qls? 55 Qls? 74 72 72 70 55 65 75 Tcw 80 72 Tcd 75 Tcw-sh Qha Qls? Unit Explanation Qls? Tcd 70 Unit Correlation 65 70 60 Tcd 80 77 Active wash deposits within major river channels (Holocene) 70 Tcw 70 Qw - Composed of 67 65 62 75 Tcw Qha 50 75 65 Tcd unconsolidated silt, sand and gravel. Qw Qha Qha Qhf Holocene 50 Tcd 75 Tcw-sh 60 52 Qpa 55 66 Alluvial and colluvial deposits, undivided (Holocene) 72 Qha - Located on the floors of Tcw 74 Qpa Qls QUATERNARY 70 Tcw-sh 55 valleys; includes active stream deposits in hill slope areas; composed of 72 Tcw 75 65 unconsolidated sandy clay with some gravel. Pleistocene 62 82 Qpf Tcw-sh 50 63 75 73 Qha Qpa Alluvial fan deposits (Holocene) Tcw-sh Qhf - Deposited by streams emanating from mountain Qpf 63 Qha Tcw 65 Tcw canyons onto alluvial valley floors; deposits originate as debris flows, hyper- Tp Tcw-sh 73 66 concentrated mudflows, or braided stream flows; composed of moderately to Pliocene 70 42 52 Ts Ts 65 poorly sorted, and moderately to poorly bedded, sandy clay with some gravel. 63 74 75 60 Tsq 50 75 60 63 Qls Landslide deposits (Holocene to late Pleistocene) 65 65 Qpa - Includes numerous active 65 70 Ts landslides, composed of weathered, broken up rocks; extremely susceptible to Tmu 65 Qha 60 Qha Tcw 83 51 64 renewed landsliding, including their head scarp areas. Tml 64 Ts 62 70 72 Qpa Miocene 72 55 72 Tr Tcw 74 50 Qpa Alluvial deposits, undivided (late Pleistocene) - Consists of semi-consolidated silt, CENOZOIC 60 70 55 70 sand, clay, and gravel. 50 50 70 Qls? Qpa 74 73 Qha 74 74 75 Tv 55 65 75 70 75 Qpa 72 75 71 Alluvial fan deposits (late to middle Pleistocene) 50 Qpf - Semi-consolidated poorly sorted TERTIARY 70 74 gravel, boulder, sand, silt and clay; often form elevated, slightly tilted, terraces on 50 Ts Ts Oligocene 47 80 72 hill slope areas. 50 Qha 75 61 Qpa 42 70 70 65 Ts Tcw Qpa 35 45 Qpa 82 Tp Pico Formation, undivided (Pliocene) 37 40 74 - Composed of claystone, siltstone, and Tcw-sh 45 41 sandstone; locally pebbly; generally susceptible to landsliding. Ts Qha 40 43 45 Tcd Qw 30 44 50 72 40 30 25 65 60 Tsq Sisquoc Shale (Pliocene-Miocene) - Silty shale and claystone; generally susceptible 32 35 34 42 30 Qha Eocene 30 32 37 to landsliding. Locally contains siliceous shale similar to the Monterey Formation. 55 45 Tma 25 75 40 40 34 Ts 35 23 Tmu Monterey Formation (middle and late Miocene) 32 30 Ts 62 - Consists of siliceous and Tj 69 diatomaceous shale and some sandstone and limestone; generally susceptible to 35 30 35 35 35 Tml 25 Qls? 55 landsliding. Tml = lower section, containing punky thin-bedded shale; Tmu = upper 28 Qls? 40 55 60 31 32 33 Qha section, composed of platy brittle siliceous thin-bedded shale. Ku CRETACEOUS MESOZOIC Tcw 34 Qpa 27 30 25 37 Tr Rincon Shale (early Miocene) - Composed of shale and siltstone; generally 30 30 susceptible to landsliding. 35 24 55 ? 30 40 46 ? 45 35 45 27 Tv Vaqueros Sandstone (early Miocene) 30 35 Qpa - Consists of sandstone, locally calcareous. 32 45 Qpa 35 30 23 35 45 ? Ts Sespe Formation (Oligocene) Ts 30 Ts 44 Qpa - Composed of sandstone; locally pebbly, siltstone and References 35 Qpa 35 Ts claystone; rocks are generally reddish in color. 32 35 40 30 15 The bedrock geology is largely modified from Dibblee (1987). Qha 35 Ts 10 Tcw 30 25 34 Qpa Coldwater Sandstone (late Eocene) - Composed of hard arkosic sandstone with 30 32 32 siltstone and shale interbeds; locally reddish in color, similar to appearance of Barnard, M., 1979, Geologic map of the Lake Casitas area in Geology of the Lake Casitas area, Ventura County, Qls Tcw-sh California: Field trip guidebook, Coast Geological Society and Pacific Section, American Association of Petroleum Qpa 47 40 Qha Sespe Formation. Tcw-sh consists predominantly of shale. 29 30 Ts Geologists, 1979 Spring field trip, 57 p. Ts Cozy Dell Shale (late Eocene) Tcd - Consists of micaceous shale with arkosic sandstone California Division of Mines and Geology, 1986, Earthquake Fault Zones, Matilija Quadrangle, Official Map of July 1, 25 35 interbeds; generally susceptible to landsliding. 1986, scale 1:24,000. 27 35 Qpa Ts 35 23 Qpa Qha Qpa Matilija Sandstone (middle to late Eocene) 25 30 Tma - Composed of hard arkosic sandstone Clark, M.N., 1982, Tectonic geomorphology and neotectonics of the Ojai Valley and upper Ventura River: University of 25 28 Ts 25 25 Ts Ts with micaceous shale interbeds. California, Santa Barbara, M.S. thesis, 77 p., 5 plates, scale 1:24,000. Ts 26 Qls? 70 Dibblee, T.W., Jr., 1987. Geologic map of the Matilija Quadrangle, Ventura County, California: Dibblee Geological 35 24 Qpa Qpa ? Tj Juncal Formation (early to middle Eocene) - Consists of micaceous shale with 35 30 SANTA ANA FAULT PARIDA - arkosic sandstone interbeds; generally susceptible to landsliding. Foundation Map DF-12, scale 1:24,000. Ts Qpa YO 25 15 30 RO 55 35 25 D AR Ts 28 24 U 17 Ts 15 Ts Qpa 45 Tv Earth Technology Corporation (ERTEC), 1981, Seismotectonic study for Casitas Dam and vicinity, Ventura County, 30 Qpa Ku Unnamed conglomerate (late Cretaceous) 15 T Tv - Conglomerate with arkosic sandstone California: Report prepared by Ertec Western for U.S. Bureau of Reclamation, Contract No. 1-07-DV-0112, Ertec 24 30 25 L 57 AU 55 and micaceous shale interbeds. Project No. 81-159, 96 p., 7 plates, scale 1:12,000. Ts Qha 10 Ts F 20 10 Qha 61 30 43 Tr 25 15 A Qpa 45 40 V Qha Tr Edwards, R.D., Rabey, D.F., and Kover, R.W., 1970, Soil survey of the Ventura area, California: U.S. Department of 20 Qpa Tr O 15 20 25 N Agriculture, Soil Conservation Services, 151 p., scale 1:24,000. Ts A Qls? 20 L 22 15 Qpa IL Qls Qls? 21 Ts Ts 15 32 V Qpa ? LT Tr Qls? Evans, J.R., Gray, C.H., Jr., Cleveland, G.B. and others, 1971, Analysis of mudslide risk in southern Ventura County, 41 FAU 41 24 25 California, in California Division of Mines and Geology, Open-File Report 72-23, Part 1, 83 p.; and Regional Qha 44 Qpa Qls Qls Symbol Explanation Qw Tr Landslide Prediction, Part 2, 33 p. TA 25 8 47 44 36 31 27 33 30 30 IS Tr 40 10 40 42 26 V Qls? Qw Qpa Ts A Qls? Tr Qha D L Qpa Tr Huftile, G.J., 1991a, Thin-skinned tectonics of the Upper Ojai Valley and Sulphur Mountain area, Ventura Basin, 30 Qpa Tr Contact between map units - Dashed where approximately located or inferred; RROYO PARIDA FAULT 30 Ts U Tr Qls? Qls California: American Association of Petroleum Geologists Bulletin, v. 75, no. 8, p. 1353-1373. Ts A 35 Tr 34 Qha Qha 27 Qls? dotted where concealed. 35 25 32 11 Tr Qls 30 24 31 Qpa Huftile, G.J., 1991b, Displacement transfer between the Red Mountain and San Cayetano faults, 33 32 25 Qha Qha in Active folding and 45 41 Qls 36 27 reverse faulting in the western Transverse Ranges, southern California: Field Trip Guidebook to accompany the D U Fault - Solid where accurately located; long dash where approximately located; 35 32 30 33 Qls ? Tr Qpa U Tr 1991 Geological Society of America Annual Meeting, San Diego, California, October 20 to 24, 63 p. 41 short dash where inferred; dotted where concealed; queried where location is Ts 35 ? 31 T 56 54 D Qha 37 Qpa 40 UL 38 Ts Tr FA Qls Qha uncertain.