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UTM GRID AND 1968 MAGNETIC NORTHDECLINATION AT CENTER OF SHEET

0°21'6 MILS

18°320 MILS

GNMN

0

0

0

1

1

1.5

.5 2

2

2Thousand Feet

Kilometers

Miles

Contour Interval 20 Feet

Dotted Lines Represent 10 Foot Contours

Scale 1:24,000

Huffman, M.E., and Armstrong, C.F., 1980, Geology for planning in Sonoma County, California: California Division of MInes

and Geology Special Report 120, 31 p., plate 3A, scale 1:62,500.

Fox, K.F. Jr., 1983, Tectonic setting of late Miocene, Pliocene and Pleistocene rocks in part of the Coast Range North of San

Francisco, California: U.S. Geological Survey Professional Paper 1239, 92 p.

Fox, K.F. Jr., Fleck, R.J., Curtis, G.H., and Meyer, C.M., 1985, Potassium-Argon and fission track ages of the Sonoma Volcanics

in an area north of San Pablo Bay, California: U.S. Geological Survey MIscellaneous Field Studies Map MF-1753,

scale 1:250,000.

Knudsen, K.L., Sowers, J.M., Witter, R.C., Wentworth, C.M., Helley, E.J., 2000, Preliminary geologic maps of the Quaternary

deposits and liquefaction susceptibility, nine-county San Francisco Bay Region, California: A digital database: U.S.

Geological Survey Open-File Report 00-44, version 1.0, scale 1:52,500.

Mankinen, E.A., 1972, Paleomagnetism and Potassium-Argon Ages of the Sonoma Volcanics, California: Geological Society of

America Bulletin, v. 83, p. 2063-2072.

McLaughlin, R.J., Sarna-Wojcicki, A.M., Fleck, R.J., Langenheim, V., Jachens, R.C., and Deino, A., 2005, Framework Geology

and Structure of the Sonoma Volcanics and Associated Sedimentary Deposits of the Right-Stepped Rodgers Creek-

Maacama Fault System and Concealed Basins Beneath Santa Rosa Plain, in Late Neogene Transition from Transform to

Subduction Margin East of the San Andreas Fault in the Wine Country of the Northern San Francisco Bay Area, California:

Field Trip Guidebook to accompany the 2005 Geological Society of America Cordilleran Section Meeting, San Jose,

California, April 29 - May 1, 52 p.

Weaver, C.E., 1949, Geology of the Coast Range immediately north of the San Francisco Bay Region, California: Geological

Society of America Memoir 35, 242 p., plates 6, 10, scale 1:62,500.

References

12121

37

780

128

12116

5Kilometers

5Miles

Mapping completed under

STATEMAP

FY 2001- 02

FY 2002- 03

FY 2003- 04

FY 2004- 05

Napa

Sonom

a

Novato

Mt. G

eorge

Napa

Petalum

a

Petalum

aRiver

Cuttings

Wharf

Glen E

llen

Cotati

Two R

ock

Sears P

oint

Yountville

Rutherford

GEOLOGIC MAP OF THE

RUTHERFORD 7.5' QUADRANGLE

SONOMA AND NAPA COUNTIES, CALIFORNIA: A DIGITAL DATABASE

VERSION 1.0

By

Kevin B. Clahan1, David L. Wagner2, Stephen P. Bezore2, Janet M.Sowers3, and Robert C. Witter3

Digital Database

By:

Carlos I. Gutierrez2

2005

Copyright © 2005 by the California Department of Conservation

California Geological Survey. All rights reserved. No part of

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."

This geologic map was funded in part by the

USGS National Cooperative Geologic Mapping

Program, STATEMAP Award no. 04HQAG0074

Topographic base from

the U.S. Geological Survey

UTM Projection, zone 10,

North American Datum 1927

STATE OF CALIFORNIA- ARNOLD SCHWARZENEGGER, GOVERNOR

THE RESOURCES AGENCY- MICHAEL CHRISMAN, SECRETARY FOR RESOURCES

DEPARTMENT OF CONSERVATION- BRIDGETT LUTHER THOMPSON, DIRECTOR

CALIFORNIA GEOLOGICAL SURVEY

JOHN G. PARRISH, PhD., STATE GEOLOGIST

38°22'30"

122°30'00" 122°22'30"

38°22'30"

122°22'30"

38°30'00"

122°30'00"

38°30'00"

1. California Geological Survey, 185 Berry St., Suite 210, San Francisco, CA 94107

2. California Geological Survey, 801 K St. MS 12-31, Sacramento, CA 95814

3. William Lettis & Associates, Inc., 1777 Botello Drive, Suite 262 Walnut Creek, CA 94596

Symbol Explanation

Strike and dip of inclined bedding.25

Landslide - Arrows indicate principal direction of movement, queried where

existence is questionable; hachures indicate headscarp (source area).

Contact between map units - Solid where accurately located, dashed where

approximately located, queried where uncertain, dotted where concealed.

Fault - Solid where accurately located, dashed where approximately located,

dotted where concealed, queried where uncertain.

25 Strike and dip of inclined foliation.

?

Syncline - Dashed where approximately located.

Dike - Dashed where approximately located.

Thrust fault - barbs on upper plate; dashed where approximately located.

Unit Correlation

af alf Qhc

Qhl

Qpf

Qhty Qhay

Qht QhaQhfQf

Qls

sp

KJfsKJfmKJgv

Th

Tsp

unconformity

unconformityTsv

TsvaslTsvabsl

Tsvatsl

Tsvrb

Tsvb

Tsvbb

TsvtyTsvamTsvt

Tsvib

TsvaTsvpf

Tsvdg

Tsvr

QUATERNARY

Pliocene

Holocene

Pleistocene

Miocene

TERTIARY

CENOZOIC

MESOZOICCRETACEOUS

JURASSIC

Landslide deposits (Holocene and Pleistocene) - Includes debris flows and block slides.

Fan deposits (Pleistocene) - Sand, gravel, silt, and clay that is moderately to poorly sorted and bedded.

Mapped on alluvial fans where greater dissection indicates latest Pleistocene age.

San Pablo (Miocene) - Marine sedimentary mudstone and sandstone. Locally contains Neroly

Formation sandstone, light-colored to bluish-gray.

Serpentinite.

Alluvium, undivided (Holocene) - Alluvium deposited on fans, terraces, or in basins; composed of sand,

gravel, silt, and clay that are poorly sorted.

Stream terrace deposits (latest Holocene <1,000 years) - Stream terraces deposited as point bar and

overbank deposits along the Napa River and Conn Creek; composed of moderately sorted clayey

sand and sandy clay with gravel.

Alluvial deposits (latest Holocene <1,000 years) - Fluvial sediment deposited on the modern flood plains.

Modern stream channel deposits (Holocene <150 years) - Deposits in active, natural stream channels;

consists of loose alluvial sand, gravel, and silt.

Artificial fill (Holocene, historic) - May be engineered and/or non-engineered.

Artificial levee fill (Holocene, historic) - May be engineered and/or non-engineered.

Alluvial fan deposits (Holocene <10,000 years) - Alluvial fan sediment deposited by streams emanating

from mountain drainages onto alluvial valleys; composed of moderately to poorly sorted sand,

gravel, silt and clay.

Fan levee deposits (Holocene) - Fan sediments deposited as long, low ridges oriented down fan.

Unit Explanation

(See Knudsen and others (2000), for more information on Quaternary units).

Alluvial fan deposits (latest Pleistocene <~30,000 years to Holocene) - Sand, gravel, silt and clay

mapped on gently sloping, fan-shaped, relatively undissected alluvial surfaces.

Stream terrace deposits (Holocene) - Stream terraces deposited as point bar and

overbank deposits; composed of moderately to well-sorted and bedded sand, gravel, silt, and

minor clay.

Franciscan Complex melange (Early Cretaceous and Late Jurassic) - Tectonic mixture of masses of

resistant rock including sandstone, altered mafic volcanics (greenstone), chert, gabbro, and exotic

metamorphic rocks imbedded in a sheared shaley matrix.

Great Valley Sequence (Early Cretaceous and Late Jurassic) - Sandstone, pebble conglomerate,

siltstone, and shale.

Sonoma Volcanics (Pliocene to Miocene)

Tsv - Undifferentiated Sonoma volcanics consisting of mafic lava flows and tuffs, rhyolite to dacite

ash flow tuff, lava flows, intrusions, breccia; also includes tuffaceous sediment.

Tsvpf - Ash flow tuff and welded ash flow tuff, locally perlitic. Includes the 3.34-3.19 tuff of Petrified

Forest (Fox and others, 1985, McLaughlin and others, 2005).

Tsvb - Olivine basalt lava flows.

Tsva - Andesite lava flows of Mt. Veeder.

Tsvib - Basalt plugs and dikes.

Tsvdg - Dacite of Mt. George - Flows, domes and shallow intrusions of gray to tan porphyritic

dacite. The dacite is typically strongly flow banded. The upper surfaces of flows and

the margins of domes and intrusions are commonly perlitic. The base of the flows is a

black porphyritic pitchstone and pitchstone breccia. K-Ar ages for the dacite are

4.3±0.2 and 3.73±1.23 Ma (Mankinen, 1972; Fox and others, 1985).

Tsvrb - Rhyolite of Bismark Knob - Plagioclase phyric, bluish-gray rhyolite and/or dacite tuff. Often

has near-source breccia; some water-laid deposits.

Tsvbb - Basalt of Bismark Knob - Plagioclase, pyroxene, olivine phyric, flow basalt. Pyroxene

phenocrysts have distinctive yellow alteration.

Tsvam - Andesite of Mission Highlands - Gray, plagioclase phyric, andesite interbedded with tuff.

Locally has a platy foliation.

Tsvty - White pumiceous tuff; locally contains mudstone clasts from underlying Great Valley

Sequence. Contains an ashflow tuff similar to or equivalent to 4.83 Ma Lawlor tuff

(Andrei Sarna-Wojcicki and Elmira Wan, personal communication, 2005).

Tsvt - Light colored tuff, lithic rich in places. Locally includes tuffaceous, diatomaceous lacustrine

sediments.

Tsvr - Rhyolite lava flows and flow breccias, undifferentiated, light colored.

Tsvasl - Andesite flows of Stags Leap.

Tsvabsl - Andesite flow breccia of Stags Leap.

Tsvatsl - Andesite ash flow tuff and tuff breccia of Stags Leap.

KJfm

KJfs

sp

KJgv

Tsp

Qls

Th

Qha

Qhty

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af

alf

Qhf

Qhl

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Tsvdg

Tsvb

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TsvaslTsvabsl

Tsvatsl

Franciscan graywacke (Jurassic-Cretaceous). Thick-bedded graywacke with minor interbedded

shale. The graywacke is moderately to intensely sheared but lacks tectonic blocks characteristic

of Franciscan melange.

Tsv

Tsva

Huichica Formation (Pliocene) - Gravel, sand, reworked tuff, and clay. A tuff interbed yields a K-Ar

date of 4.09±0.19 Ma (Fox and others, 1985).

Preliminary Geologic Map available from:

http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm

Revised: 03/01/2006