1 Copyright © 2002 by the California Department of Conservation All rights reserved. No part of California Geological Survey. this publication may be reproduced without written consent of the California Geological Survey. "The Department of Conservation makes no warranties as to the suitability of this product for any given purpose." Quaternary Tertiary Cretaceous Jurassic } } } }
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volcanic Ar Geochronology, geochemistry, and structural reinterpretation geochemistry, Ar Geochronology, 39 Tsv
ge. Tectonic mixture of ma Tectonic ge. Ar/ Qhbm 40 Thrust fault- solid where accurately located; dashed approximately located; short dash where inferred; dotted concealed. Fault - solid where accurately located, dashed approximately located; short dash where inferred; dotted concealed. U = upthrown block, Arrow and number indicate direction angle D = downthrown block. of dip fault plane. Inclined Horizontal Landslide - arrows indicate principal direction of movement. Queried where questionable. Detatchment surfaces of mega-landslide masses. Fault Zone. Tolay Zone of intense shearing along the
stone Syncline - Dashed where approximately located; dotted concealed.
phic rocks imbedded in a Contact between map units - solid where accurately located, dashed approximately located; short dash where inferred; dotted concealed.
plex melan Strike and dip of sedimentary beds: Wagner, D. L., and Bortugno, E. J., Geologic Map of the Santa Rosa Quadrangle, Wagner, by in Tdm Tdt Tdr By 2002 sp Qoa and Victoria D. Walker and Victoria
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scan Com Digital Database , Stephen P. Bezore , Stephen P. 25 VERSION 1.0 2 Tpl
Franci sandstone, altered mafic metamor large enough to be shown at t
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sch - schist and semischist Qhf Tpm Serpentinized ultramafic rocks. Symbol Explanation Tpu 27 References The structure and stratigraphy of portions the Mare Island, Sears Point, Richmond Cebull, S.E., 1958, California: California 1980, Geology for planning in Sonoma County, Armstrong, C.F., M.E., and Huffman, Thesis, 79 p., scale 1:24.000. M.A. California: University of California, Berkeley, quadrangles, setting of late Miocene, Pliocene, and Pleistocene rocks in part the Coast Tectonic 1983, Jr., Fox, K.F. Division of Mines and Geology Special Report 120, 31 p., plate 3A, scale 1:62,500. E.J., 1973, Preliminary geologic map of eastern Sonoma J.A., and Helley, Sims, J.D., Bartow, Jr., Fox, K.F. Ranges north of San Francisco, California: U.S. Geological Survey Professional Paper 1239, 92 p. C.M., 1985, Potassium-Argon and fission-track ages of the Fleck, R.J., Curtis, G.H., and Meyer, Jr., California: U.S. Geological Survey Miscellaneous Field Studies Fox, K.F. County and western Napa County, Map MF-483, scale 1:62,500. Thermal springs and wells radiometric ages of rocks in the Santa Rosa Quadrangle, R., 1982, California: U.S. Geological Survey F. Kelly, in an area north of San Pablo Bay, Sonoma Volcanics Miscellaneous Field Studies Map MF-1753, scale 1:250,000. E.J., 2000, Preliminary geologic C.M., and Helley, R.C., Wentworth, Knudsen, K.L., Sowers, J.M., Witter, California, California: Department of Conservation, Division Mines and Geology Regional Geologic Map 2A. nine-county San Francisco Bay of the Quaternary deposits and liquefaction susceptibility, maps 1935, Geological observations in the Petaluma District, California: Bulletin of 1.0, T.L., digital database: U.S. Geological Survey Open File Report 00-44, ver. A Morse, R.R. and Bailey, Region, California: scale 1:52,000. California: C.E., 2002, Neotectonics of the southern Rodgers Creek Fault, Sonoma County, Randolph-Loar, America, vol 46, p. 1437-1456. Society of Geological M.S. thesis, 54 p. San Francisco State University, Weaver, C.E., 1949, Geology and mineral deposits of an area north the San Francisco Bay Region, Weaver, M.R., 1989, K-Ar and America Youngman, California: California Division of Mines Bulletin 149, 135 p. (also Geological Society Memoir 35). California: University of California M.S. Field, Sonoma County, of the southern Sonoma Volcanic 92 p. thesis, ~ ~ ~ af afbm alf Qf sp Th Tp Qhc Qhly Qhty Qhay QTu KJfm Jason D. Little KJfm Unit Correlation GEOLOGIC MAP OF THE OF GEOLOGIC MAP 1. California Geological Survey, 801 K st. MS 12-31, Sacramento, CA 95814 801 K st. MS 12-31, Sacramento, CA 1. California Geological Survey, SEARS POINT 7.5' QUADRANGLE SEARS POINT 2. William Lettis & Associates, Inc., 1777 Botello Drive, Suite 262 Walnut Creek, CA 94596 Creek, CA Associates, Inc., 1777 Botello Drive, Suite 262 Walnut 2. William Lettis & , Carolyn E. Randolph-Loar 1 INTERSTATE 780 12 INTERSTATE 80 29
ings Wharf
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Petaluma Petalum David L. Wagner ma lu
4mi Peta 4km 0 Donnell Ranch Volcanics of Youngman (1989). Basalt and basaltic andesite flows, Youngman of Donnell Ranch Volcanics Creek in the Tolay occur west of breccia, and scoria. Rhyolite flow tuff is interbedded with the western part of the quadrangle. Cream colored tuff is 10.64 Ma The age range for the Donnell Ranch Volcanics mafic volcanics. volcanics of Morse and Tolay to possibly as young 8.52 Ma. Part of the are subdivided as follows. The Donnell Ranch Volcanics Bailey (1935). Tdm- Mafic volcanics including mafic flows and breccia. mostly basalt interbedded with mafic volcanics. Tdt- Light colored tuff basaltic andesite flows and breccia. Scoria is abundant locally. radiometric date of 9.56 Ma on the A Tdr- Rhyolite to dacite flows and tuff. This unit is called was reported by Fox and others (1985). rhyolite (1949). Rhyolite of St. Helena by Weaver the Petaluma Formation. A predominantly lacustrine and fluvial deposit with esturine A Petaluma Formation. chert, lignite, and limestone. conglomerate, with minor silicified tuff, and transitional marine horizons consisting of siltstone, sandstone, shale, Divided into three subunits: Tpu- Upper Petaluma Fm. Massive, well sorted sandstone, siltstone, and conglomerate. Conglomerate is rich in laminated siliceous volcanics, with Tertiary shale (Monterey Fm.) fragments and dated at 6.26 Ma (Robert (Trt), Tuff The Roblar Franciscan clasts. Fleck, written communication, 2002) is interbedded with the Upper Tpm- Middle Petaluma Fm. Siltstone with interbedded conglomerate. Petaluma. Clasts in conglomerate are mostly pebbles derived from the sandstone Tertiary Franciscan, but clasts of Cretaceous and volcanics are present. Minor siliceous shale Tertiary as well Tpl- Lower Petaluma Fm. Dominantly bluish to green clayey siltstone and fragments from the Monterey Formation are also present. siliceous limestone, lignite, shale with interbeds of silicified tuff, and rare bituminous chert. Laminated siltstone near the base in Creek and elsewhere have yielded Tolay places. Localities near breccia with tuff Mafic lava flows, breccias, agglomerate tuff, Sonoma Volcanics- transitional marine and estuarine horizons in a predominantly lacustrine and fluvial deposit sediments; also includes dacitic to rhyolitic lava interbedded fuffaceous The age range for the sediment. and tuffaceous flows, debris tuff, on this quadrangle is 8.65 to 3.80 Ma (Fox and others, Volcanics Sonoma are divided into the The Sonoma Volcanics 1989). Youngman, 1985; following subunits. Age Andesite and basaltic andesite. Mafic flows and breccias. Tsvm- sediments. Interbedded sand and interbedded tuffaceous Silicic tuff Tsvt- 1989). range is 7.28 to 3.80 Ma (Youngman, Rhyolitic to dacitic flows, breccias, and sediments. Pink, white, gray, Tsvr- and gravel is similar to the MIddle Petaluma Formation. brown flow banded rhyolite in flows, debris flows and breccia. Dates (Ar/Ar) range from 7.36 Interbeds of sand, gravel, and tuff. 1989; Fox and others, Youngman, 2002; Ma (Randolph-Loar, to 8.11 1985). Basalt that occurs along the Rodgers Creek Fault Zone. Huichica Formation. Gravel, sand, reworked tuff and clay. Sediments derived and clay. Huichica Formation. Gravel, sand, reworked tuff interbed yields a K/Ar date tuff A mostly from the Sonoma Volcanics. of 4.09+-0.19 [Andrei Sarna, written communication, 1981 reported in Kelly (1982)]. Artificial fill Artificial fill placed over bay mud Artificial levee fill Late Holocene to modern (<150 years) stream channel deposits in active, natural Latest Holocene (<~1,000 years) alluvial fan levee deposits. Natural deposits of stream channels. Consists of loose alluvial sand, gravel, and silt. Latest Holocene stream terrace deposits. Stream terraces are deposited alluvial deposits along Sonoma Creek. Latest Holocene alluvial deposits. Fluvial sediment deposited on the as point bar and overbank deposits by Sonoma Creek. peat, and fine sand deposited at or near Holocene (<10,000 years) bay mud. Silt, clay, modern flood plain of Sonoma Creek. sea level in San Pablo Bay. Holocene alluvial fan deposits. Sand, gravel, silt, and clay deposited by streams emanating from canyons onto alluvial valley floors. Alluvium deposited on fans, terraces, or Holocene alluvium, undivided. Sediment is poorly to moderatly sorted and bedded. in basins. Sand, gravel, and silt that are poorly sorted. Latest Pleistocene (<30,000 years) to Holocene alluvial fan deposits. Sand, gravel, silt Latest Pleistocene fan deposits. Sand, gravel, silt, and clay that is and clay mapped on gently sloping, fan-shaped, relatively undissected alluvial surfaces. moderately to poorly sorted and bedded. Mapped on alluvial fans where greater dissection indicates latest Pleistocene age. Alluvial fan, stream Early to late Pleistocene alluvial deposits, undivided. is gently rolling Topography terrace, basin, and channel deposits. and clay of unknown age. Sediments derived Gravel, sand, reworked tuff with little or no original alluvial surfaces preserved; moderately to deeply dissected. mostly from the Sonoma Volcanics. Landslides. Includes debris flow and block slump landslides. Arrows show the direction of movement. Tpl Tsvt Tpu Tsvr Tpm Tsvm af Tdt Th Tdr Qf alf Qls Tvb Tdm Qhf Qpf Qhc Qha Qoa Qhly Trt Qhty QTu afbm Qhay Tp Qhbm Tsv Unit Explanation (See Knudsen and others (2000), for more information on Quaternary units). SONOMA, SOLANO, AND NAPA COUNTIES, CALIFORNIA: A DIGITAL DATABASE DIGITAL A COUNTIES, CALIFORNIA: AND NAPA SONOMA, SOLANO, Qhbm Qhf Tsvm Qhf Qhbm af Qhbm Qhbm Qhbm Qhbm Qhbm Qhbm alf Qhbm Qha Qhbm Qhbm Qhbm Qpf afbm Th alf Qhbm Qhbm Qhbm Qhbm Qhbm Qhbm This geologic map was funded in part by the USGS National Cooperative Geologic Mapping no. 01HQAG0092 Award Program, Statemap Qhbm Qhbm alf Qhbm af Qhbm Qha Qhbm Qhbm Qha Qhf af af Qhbm Th Qhbm Qhbm Qhf alf Qhbm Qhbm alf afbm alf Qhbm alf alf Qhbm Qhbm Qhbm Qof Miles Qhbm 2 Qhbm Qhbm Qhbm Qhbm Qhbm Qhbm Qhbm alf Qhbm Qhbm Qhbm Qhbm Qhbm Qhbm Kilometers 2 alf alf Qhbm alf afbm Qhbm Qhbm Qhbm Qof Qhbm alf Qhbm Thousand Feet Thousand afbm Qhc 2 Qhbm afbm Qhbm Qof Qof afbm alf Qhbm Qhbm Qhc Qhbm 1 1 1 Qhbm alf alf Qhbm alf Qhbm Qof Qf Tsvm Qof af Qhbm Qf af Qhc Contour Interval: 20 feet af 0 alf Qf afbm Qf
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49 R 18 18 Tdm 45 Qls Tdm Tpl? Qls Qf Tsvr Tpl? 63 Tsvt Qha Tpm Qf ss Tpu 20 Qha Qls Tsvm 40 Qha Tdr Tsvt Qhbm Qls Tdm ch Tdm Qls Tsvt Tpu Qha Tsvt Tdr gs Tsvm Qoa Tvb Tpm 1 Qls 20 45 35 af Tdm Tsvr KJfm 35 QTu Qls 55 50 sch Tdm 80 60 Trt Qha Tsvm 54 42 Tpl? Tpl Qls Tsvt 40 QTu Tsvr Tp Qoa 40 48 Tdt Qhc Tdt? Tsvt 30 Tdm Tpl 49 Qo KJfm 38 Tp 30 Tsvm Tsvm Qhf Tdm Qha 30 Tdm? QTu Qls Tdr? Tpm Tsvr Tsvt Tdm CALIFORNIA GEOLOGICAL SURVEY GEOLOGICAL CALIFORNIA GEOLOGIST STATE DAVIS, JAMES F. 20 Qhf Tsvr Qf Qf Qhf Tdm Qha Tsvr Topographic base from Topographic the U.S. Geological Survey Polyconic Projection