33 22' 30"117 07' 30"

33 30' 00"117 07' 30"

33 22' 30"117 00' 00"

33 30' 00"117 00' 00"

STATE OF CALIFORNIA - GRAY DAVIS GOVERNORTHE RESOURCES AGENCY - MARY NICHOLS, SECRETARY FOR RESOURCES

DEPARTMENT OF CONSERVATION - DARRYL YOUNG, DIRECTOR Prepared in cooperation with the U.S. Geological SurveyDIVISION OF MINES AND GEOLOGYJAMES F. DAVIS, STATE GEOLOGIST

Topographic base by U.S. Geological Survey7.5’ Pechanga QuadranglePolyconic projection, contour interval 20 feet,dotted lines 10 feet.

A. Hanley, J.B. and Janhs, R.H., 1950 unpublished geological maps of thePala and Rincon pegmatite districts, San Diego County, California: Un-published U.S. Geological Survey mapping (scale 1:24,000). This mappingwas used with slight modification for the basement rock geology throughoutthe central portion of the quadrangle.

B. Irwin, W.P. and Greene, R.C., 1970, Studies related to wilderness primi-tive areas, Agua Tibia, California: U.S. Geological Survey Bulletin 1319-A,19 p., map scale 1:48,000. This mapping was used with slight modificationfor the basement rock geology in the east-central part of the quadrangle.

C. Jahns, R.H., and Wright, L.A., 1951, Gem- and lithium-bearing pegmatitesof the Pala district, San Diego County, California: California Division ofMines and Geology Special Report 7-A, 72 p., map scale 1:18,000. Thismapping was used with slight modification for the pegmatites and adjacentbedrock geology in the Pala gem district.

D. Kennedy, M.P., 1977, Recency and character of faulting along the Elsinorefault zone in southern Riverside County, California: California Divisionof Mines and Geology Special Report 131, 12 p., map scale 1:24,000. Thismapping was used with slight modification for the northern half of thequadrangle.

E. Kennedy, M.P., 2000, New 1:24,000-scale geologic mapping completedbetween July 1999, and June 2000.

F. Larsen, E.S. Jr., 1948, Batholith and associated rocks of Corona,Elsinore and San Luis Rey quadrangles, southern California: GeologicalSociety of America Memoir 29, 182 p., scale 1:125,000. This mapping wasuseful in depicting regional contacts between major plutons but the verysmall scale does not allow direct use of these contacts at 1:24,000.

D,E

B,D,E,F

B,E,F

A,E

A,D,E

C,EE,FA,E

REFERENCES

Contact between map units.

Fault - dashed where inferred, dotted where concealed.Arrow and number indicate direction and angle of dip of fault plane.

Anticline - solid where accurately located; dotted where concealed.

Strike and dip of inclined sedimentary beds.

Strike and dip of overturned sedimentary beds.

Strike and dip of foliation.

Strike of vertical foliation.

Landslide - arrows indicate principal direction of movement.

Air photo lineament - Mostly joints and minor faults.

Pegmatite dike.

Closed depression.

65

18

18

18

Syncline - solid where accurately located; dotted where concealed.

MAP SYMBOLS

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Qya

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Qyc

Qoc

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QolsQp

Tt

Qa

Kr Kp Kat Kgd Kgdf Kt Kgb KgbfKJqKJs

Tv

PlioceneMiocene

Pleistocene

HoloceneQUATERNARY

CRETACEOUS

JURASSIC

CENOZOIC

MESOZOIC

TERTIARY

CORRELATION OF MAP UNITS

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Qa

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DESCRIPTION OF MAP UNITS

MODERN SURFICIAL DEPOSITS - Sediment that has been recently transportedand deposited in channels and washes, on surfaces of alluvial fans and alluvialplains, and on hillslopes and in artificial fills. Soil-profile development is non-existant. Includes:

Active channel and wash deposits (late Holocene) - Unconsolidated to locally poorly unconsolidated sand and gravel deposits in active washes of streams.

Active alluvial flood plain deposits (late Holocene) - Unconsolidated to locally poorlyunconsolidated sand and gravel deposits in active alluvial flood plains.

YOUNG SURFICIAL DEPOSITS - Sedimentary units that are slightly consolidated tocemented and slightly to moderately dissected. Alluvial fan deposits typically have highcoarse:fine clast ratios. Younger surficial units have upper surfaces that are capped byslight to moderately developed pedogenic-soil profiles. Includes:

Young alluvial flood plain deposits (Holocene and late Pleistocene) - Mostly poorly consolidated, poorly sorted, permeable flood plain deposits.

Young alluvial fan deposists (Holocene and late Pleistocene) - Mostly poorly consolidatedand very poorly sorted sand, gravel, cobble and boulder deposits in young alluvial fans.

Young colluvial deposits (Holocene and late Pleistcene) - Mostly poorly consolidated and poorly sorted slope wash and stream deposits.

OLD SURFICIAL DEPOSITS - Sediments that are moderately consolidated and slightly to moderately dissected. Older surficial deposits have upper surfaces that are capped bymoderate to well-developed pedogenic soils. Includes:

Older alluvial flood plain deposits (Pleistocene, younger than 500,000 years) - Mostlymoderately well consolidated, poorly sorted, permeable flood plain depostits. Older colluvial deposits (Pleistocene, younger than 500,000 years) - Mostly moderately well consolidated, poorly sorted slope wash and stream deposits.Older fan deposits (Pleistocene, younger than 500,000 years) - Mostly poorly consolidated fan, debris flow and talus deposits. Clasts possess a moderately well developed clay coatingbut are otherwise fresh.Older landslide deposits (Pleistocene, younger than 500,000 years) - Landslide slump androck fall depostits.

VERY OLD SURFICIAL UNITS - Sediments that are slightly to well consolidated to indurated, and moderately to well dissected. Upper surfaces are capped by moderate to well-developedpedogenic soils. Includes:

Very old alluvial flood plain deposits (early Pleistocene) - Mostly well-indurated, poorly sorted,semi-permeable clay and sand flood plain deposits.Very old colluvial deposits (early Pleistocene) - Mostly well-indurated, poorly sorted, hillslope,clay and sand colluvial deposits.Very old alluvial fan deposits (early Pleistocene) - Mostly very well-indurated, reddish-brown,sand and cobble, early Pleistocene aluvial fan deposits.Pauba Formation (early Pleistocene) - Light-brown moderately well-indurated, extensivelycrossbedded, channeled and filled sandstone and siltstone that contains occassional interveningcobble-and -boulder conglomerate beds.Dripping Springs Formation (early Pleistocene) - Pebble, cobble and boulder fanglomeratein a reddish-brown, poorly consolidated, poorly sorted sandstone matrix.

BEDROCK UNITS

Temecula Arkose (Pleistocene) - Pale greenish-yellow, well-indurated, medium- and coarse-grained sandstone with thin interstratified beds of fine-grained, tuffaceous sandstone, siltstone,and claystone. Pebble and cobble conglomerate interbeds composed of locally derived basement rock clasts are also common and range in thickness from a few centimeters to a meter or more.

Basalt (Miocene) - Dark-gray and black, fine-grained basalt.

Granodiorite of Rainbow (Cretaceous) - Leucocratic hornblende-biotite granodiorite;medium- to coarse-grained, massive.

Granodiorite of Pala (Cretaceous) - Leucocratic granodiorite and migmatite; fine- to medium-grained.

Gabbro of Agua Tibia Mountain (Cretaceous) - Hornblende gabbro; medium- to coarse-grained, massive to foliate. This gabbro often contains minor biotite and quartz (quartz bearing gabbro).Granodiorite undivided (Cretaceous) - Mostly hornblende-biotite granodiorite;medium- to coarse-grained.Granodiorite undivided fault part (Cretaceous) - Leucocratic hornblende-biotite granodiorite thathas been extensively sheared along the Elsinore fault zone.Tonalite undivided (Cretaceous) - Mainly hornblende-biotite tonalite; coarse-grained, light gray.

Gabbro undivided (Cretaceous) - Mosltybiotite-hornblende-hypersthene gabbro; coarse-grained, dark gray, massive.Gabbro undivided fault part (Cretaceous) - Mosltybiotite-hornblende-hypersthene gabbro that has been extensively sheared along the Elsinore fault zone.Quartzite and quartz conglomerate (Cretaceous and Jurassic) - Mostly quartzite, quartz conglomerateand meta-arkose.Schist with minor amphibolite and marble (Cretaceous and Jurassic) - Mostly quartz-mica-schist,quartz-mica amphibole schist, and feldspathic amphibole schist.Metavolcanic and metasedimentary rocks undivided (Cretaceous and Jurassic) - Low grade(greenschist facies) rocks that are in part coeval with and in part older than the Cretaceous plutonic rocks they lie in contact with.

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This geologic map was funded in part by the U.S. Geological Survey National Cooperative Geologic Mapping Program, STATEMAP Award no. 99HQAG0134.

Copyright 2000 by the California Department of Conservation Division of Mines and Geology. All rights reserved. No part ofthis publication may be reproduced without written consent of theDivision of Mines and Geology.

"The Department of Conservation makes no warranties as to thesuitability of this product for any given purpose."

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UTM GRID AND 1988 MAGNETIC NORTHDECLINATION AT CENTER OF SHEET

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DEPARTMENT OFCONSERVATION Division ofMines and Geology

GEOLOGIC MAP OF THEPECHANGA 7.5' QUADRANGLE

SAN DIEGO AND RIVERSIDE COUNTIES, CALIFORNIA: A DIGITAL DATABASE

VERSION 1.0By

Michael P. Kennedy1

Digital Databaseby

Brad L. Nelson2 and Rachel M. Hauser2

2000

1. California Division of Mines and Geology, Los Angeles, CA2. U. S. Geological Survey, Riverside, CA

QuartzSyenite

QuartzMonzonite

QuartzMonzodiorite

Syenite Monzonite Monzodiorite

Granite

Alka

li-fel

dspa

r Gra

nite

Tonalite

Diorite

Syen

ogra

nite

Granodiorite

Mon

zogr

anite

Quartz

Diorite

90 65 35 10

5

20

60Q Q

A P

60

20

5

60

Classification of plutonic rock types (from IUGA, 1973, and *Streckeisen, 1973). A, alkali feldspar; P, plagioclase feldspar; Q, quartz.

*Streckeisen, A.L., 1973, Plutonic rocks--Classification and nomenclature recommended by the IUGA Subcommission on Systematics of Igneous Rocks: Geotimes, vol.18, pp.26-30.