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PRELIMINARY GEOLOGIC MAP OF ONSHORE PORTIONS OF THECALIFORNIA GEOLOGICAL SURVEYJOHN G. PARRISH, Ph.D., STATE GEOLOGIST

PRELIMINARY GEOLOGIC MAP OF ONSHORE PORTIONS OF THE CRESCENT CITY AND ORICK

30' x 60' QUADRANGLES, CALIFORNIACompilation and Digital Preparation by

Marc Delattre and Anne Rosinski

2012

Copyright © 2012 by the California Department of Conservation. All rights reserved. No part of this publication may be reproducedwithout written consent of the California Geological Survey.

The Department of Conservation makes no warranties as to the suitability of this product for any particular purpose.

41°00'

42°00'

124°00'124°52'30”

124°52'30” 124°00'42°00'

Projection: Uiversal Transverse Mercator, Zone 10N, North American Datum 1927.

Topographic base from USGS Crescent City and Orick 30'x60' quadrangles, 1983. Shaded relief image derived from USGS 1/3 arc-second National Elevation Dataset (NED).

This geologic map was funded in part by the U.S. Geological Survey National Cooperative Geologic Mapping Program, STATEMAP Award no. G11AC20220.

Geology compiled 2011-2012

41°00'

STATE OF CALIFORNIA - EDMUND G. BROWN JR., GOVERNORNATURAL RESOURCES AGENCY - JOHN LAIRD, SECRETARY

DEPARTMENT OF CONSERVATION - MARK NECHODOM, DIRECTOR

41°30'41°30'

124°15'

124°15'

CRESCENT CITY

ORICK

CRESCENT CITY AND ORICK 30' x 60' QUADRANGLES, CALIFORNIA

Preliminary Geologic Map available from:http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm

SCALE 1:100,000 6 Miles 2 0 2 4

2 0 2 4 6 Kilometers

Contour Interval: 50 metersAPPROXIMATE MEANDECLINATION, 2012

15.27°

TRU

E N

OR

THM

AG

NE

TIC

NO

RTH

?

27?

D

U

25

25

Contact between map units - Hashed where gradational; solid where accurately located, dashed where approximately located; short dash where inferred; dotted where concealed; queried where uncertain.

Fault - Solid where accurately located; dashed where approximately located; short dash where inferred; dotted where concealed; queried where uncertain; bar and ball on downthrown side. U = upthrown block, D = downthrown block.

Thrust fault - Sawteeth on upper plate; solid where accurately located; dashed where approximately located; short dash where inferred; dotted where concealed; queried where existance uncertain

Anticline - Solid where accurately located, dashed where approximately located; dotted where concealed.

Syncline - Solid where accurately located, dashed where approximately located; dotted where concealed.

25

25

25

?

?

25

25

SYMBOL EXPLANATION

?

Strike and dip of bedding:

Inclined

Vertical Overturned

Crumpled

Approximate

Strike and dip of foliation:

Iinclined

Vertical

Strike and dip of joints or fractures

Strike and dip if igneous layering

Strike and dip of dike walls

Landslide - arrows indicate principal direction of movement.

QU

ATE

RN

AR

YTE

RTI

AR

YC

RE

TAC

EO

US

JUR

AS

SIC

Hol

ocen

eP

leis

toce

neM

ioce

ne P

lioce

ne

ME

SO

ZO

ICC

EN

OZ

OIC

CRESCENT CITY

ORICK

Trinidad

Crescent City

0 10 205 Kilometers

0 6 123 Miles

Pacific Ocean

ABBREVIATED INDEX TO GEOLOGIC SOURCE DATA

9

6

1

5

7

3 2

4

10

11

8

tu

tu

tu

tu

0 6 12 sretemoliK3

0150 seliM5.2

(SEE PAMPHLET FOR COMPLETE REFERENCES)

1. Harper, 1980; Elder and Reichert, 2010; Evans, 1984; Stone, 1983, for Wimer Formation; Quaternary mapping by Delattre, this study.

2. Davenport, 1983b; Aalto, 1981; Quaternary mapping by Delattre, this study.

3. Davenport, 1983c; Back, 1957; Aalto and others, 1981; Quaternary mapping by Delattre, this study.

4. Davenport, 1983a; Back, 1957; Aalto and others, 1981; Stone, 1983, for Wimer Formation; Quaternary mapping by Delattre, this study.

5. Davenport, 1982; Back, 1957; Aalto, 2006, for Point St. George area; Polenz and Kelsey, 1999; Quaternary mapping by Delattre, this study.

6. Davenport, 1984a; Aalto and Harper, 1982; Wills, 2000; Ristau, 1979; Quaternary mapping by Delattre, this study.

7. Davenport, 1984b; Aalto and Harper, 1982; Quaternary mapping by Delattre, this study.

8. Aalto and others, 1981; Cashman and others, 1995; Kelsey and Trexler, 1989.

9. Dell’Osso and others, 2003; Cashman and others, 1995; Hardin and others, 1982; Aalto and others, 1981; Quaternary mapping by Delattre and Rosinski, this study.

10. Aalto and others, 1981; Quaternary mapping by Delattre and Rosinski, this study.

11. Aalto and others, 1981; Carver, 1992, Woodward-Clyde Consultants, 1980, and Aalto, 1989b for marine terraces; Quaternary mapping by Delattre and Rosinski, this study.

42°0'0"

41°30'0"41°30'0"

124°0'0"

41°0'0"124°0'0"

41°0'0"125°0'0"

42°0'0"125°0'0"

INDEX MAP OF 7.5’ QUADRANGLES

(Happy C

amp)

(Hoopa)

(Eureka)

WITHIN THE CRESCENT CITY AND ORICK 30’ X 60‘ QUADRANGLES

ch

mg

u

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Franciscan Complex - Central Belt

Mélange of the Central Belt (Late Cretaceous to Late Jurassic)

Greenstone block within mélange

Franciscan Complex - Eastern Belt

Broken formation (Early Cretaceous to Middle Jurassic)

Mélange unit of Crescent City area (Early Cretaceous to Middle Jurassic)

Blocks within mélange:

Blocks within mélange:

Greenstone

Greenstone

Metagraywacke

Chert

Undifferentiated

Transitional rocks of the Grogan Fault Zone (Cretaceous to Jurassic)

Coherent unit of Lacks Creek (Cretaceous to Jurassic)

Redwood Creek watershed units of Hardin and others (1982)

Metagraywacke (Cretaceous to Jurassic)

Incoherent unit of Coyote Creek (Cretaceous to Jurassic)

Redwood Creek Schist (Early Cretaceous to Late Jurassic)

Interbedded metatuff

Serpentinite block

Patricks Point unit of Aalto and others, 1981 (Cretaceous to Jurassic)

Klamath Mountains Province - Western Jurassic Belt

Josephine Ophiolite of Harper (1980)

Dike Complex (Late Jurassic)

Gabbro (Late Jurassic)

Cumulate ultramafic rocks (Late Jurassic)

Sheared serpentinite (Jurassic)

Serpentinite matrix mélange (Jurassic)

Granitic rocks

Metasedimentary rocks

Peridotite (Late Jurassic)

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Marine terrace deposits (Pleistocene)Trinidad marine terraces; names and approximate ages (ka=1000 years)from Woodward-Clyde Consultants (1980), and Carver (1992):

Patricks Pt. terrace, age 64 ka

Savage Creek terrace, age 83 ka, and McKinleyville terrace, age 96 ka

Westhaven terrace, 103 ka

Fox Farm terrace, 120 ka, and Sky Horse terrace, 130 ka

A-Line terrace, 176 ka and older

Maple Stump terrace, 200+ ka

Terrace gravels of Surpur Creek (Pleistocene)

Prairie Creek Formation (early Pleistocene to late Pliocene)

Undifferentiated marine and nonmarine overlap deposits (Pleistocene to late Pliocene?)

Wimer Formation (late Miocene)

St. George Formation (late Miocene)

Stream channel deposits (latest Holocene)

Beach deposits (latest Holocene)

Young alluvial deposits, undifferentiated (Holocene)

Young alluvial fan deposits (Holocene)

Dune sand (Holocene)

Estuarine deposits (Holocene)

Landslide deposits (historical to Pleistocene)

Alluvial deposits, undifferentiated (Holocene to latest Pleistocene)

Alluvial fan deposits (Holocene to Pleistocene)

Stream terrace deposits (early Holocene to Pleistocene)

Battery Formation (late Pleistocene)

Artificial fill (historical)

Young stream terrace deposits (Holocene)

ABBREVIATED EXPLANATION(Approximate stratigraphic relationships only; see pamphlet for more detailed information)

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