5

4

5

7

5

6

5

65

7

7

10

45

6

42

56

85

80

6576

71

73

824253

83

62

74

77

70 4582

8085

60

70

85

8371

402080

50

5060

45

60

50

50

70

7060

30

40

60

60

80

7580

8065

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3030

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40 30

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3

75

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7060

35

35 30

25

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4040

4080

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40

808080

75

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JTrm

JTrm

Ktc

Ktc

Tt

Qya

Qya

Tt

KtcKtc

Ktc

Qvof

Qvof

Qoa

Qoa

Kgd

Qoa

Kgd

Ktc

Qoa

Kt

Qoa

Ktc

Ktc

Qya

Qvof

Tt Tt

Ktc

Qya

Kgd

Kgd

Kgd

Kgd

Tt

Kt

Tt

Kt

Tt

Qvof

Tt

Tt

Qya

Qya

Ktc

KtKt

Kt

Kt

Qvoa

Qoa

Qa

Qvof

J^m

J^m

J^m

Qya

Qya

Ttu Ttu

Qvoa

Ttu

Ttl

Qa+Qya

Qa+Qya

Qya

Qa

Qa

Qa

SPRINGS

FAULT

HOT

UD

UD

AGUANGA

FAULT

Ktc

KtcKtc-w

Ktc-w

Qya

Qya

Qya

Qya

Qya Qya

Qya

Qa

Qya

Qoa

Kt

Qya

Qya

Qa

Qya

Kgd

Jmg

J^m

Kt

J^m

J^m

J^m

J^m

J^m

Qvof

J^m

Ktc

Ktc

Ktc

Lancaster

J^m

J^m

Ktc

Ktc

Kt

Kt

Kt

Ktc

Kt

GN

240MILS13

0 021MIL

MN

UTM GRID AND 1988 MAGNETIC NORTHDECLINATION AT CENTER OF SHEET

1/2

Contour Interval 40 Feet

SCALE 1:24 000

8000 FEET3000 4000 5000

.5 2 KILOMETERS0 1

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0 1000 2000 6000 7000 CGSSGSA M PSUC

Copyright © 2014 by the California Department of ConservationCalifornia Geological Survey. All rights reserved. No part ofthis publication may be reproduced without written consent of theCalifornia Geological Survey.

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

PRELIMINARY GEOLOGIC MAP OF THE AGUANGA 7.5' QUADRANGLE,SAN DIEGO AND RIVERSIDE COUNTIES, CALIFORNIA:

A DIGITAL DATABASEVersion 1.1

ByMichael P. Kennedy1 and Siang S. Tan1

2003(Revised 2014)

Digital Preparation byMatt D. O’Neal2, Carlos I. Gutierrez2 and Kelly Corriea3

1. California Geological Survey, 888 South Figueroa Street, Suite 475, Los Angeles, CA 900172. California Geological Survey, 801 K Street, MS 12-32, Sacramento, CA 95814

3. U.S. Geological Survey, Department of Earth Sciences, University of California, Riverside

Coordinate System:Universal Transverse Mercator, Zone 11N,North American Datum 1927.

Topographic base from U.S. Geological SurveyAguanga 7.5-minute Quadrangle, 1954 (Photorevised 1988).

116°52'30''33°30'

STATE OF CALIFORNIA – EDMUND G. BROWN JR., GOVERNORTHE NATURAL RESOURCES AGENCY – JOHN LAIRD, SECRETARY FOR NATURAL RESOURCES

DEPARTMENT OF CONSERVATION – MARK NECHODOM, CONSERVATION DIRECTOR CALIFORNIA GEOLOGICAL SURVEYJOHN G. PARRISH, Ph.D., STATE GEOLOGIST PRELIMINARY GEOLOGIC MAP OF THE AGUANGA 7.5’ QUADRANGLE, CALIFORNIA

Prepared in cooperation with the U.S. Geological Survey, Southern California Areal Mapping Project

116°45’33°30'

33°22'30”116°52'30''

33°22'30”116°45’

This geologic map was funded in part by the U.S. Geological Survey National Cooperative Geologic Mapping Program, STATEMAP Award no. 05HQAG0080

Bull, W.R., 1991, Geomorphic responses to climate change: New York, Oxford University Press, 326 p.Gastil, G., Girty, G., Wardlaw, M., and Davis, T., 1988, Correlation of Triassic-Jurassic sandstone in peninsular

California (abs.): Geological Society of America Abstracts with Programs, v. 20, no. 3, p. 162.Germinario, M. P. 1982, The depositional and tectonic environments of the Julian Schist, Julian, California:

Unpublished M.S. thesis, San Diego State University, San Diego, California, 95 p.Golz, D. J., Jefferson, G. T., and Kennedy, M.P., 1977, Late Pliocene vertebrate fossils from the Elsinore fault zone,

California: Journal of Paleontology, v. 51, p. 864-866.Hanley, J.B., 1951, Economic Geology of the Rincon Pegmatites, San Diego County, California: California Division of

Mines, Special Report 7-B, 24 p., scale 1:24,000.Hudson, F.S., 1922, Geology of the Cuyamaca region of California, with special reference to the origin of nickeliferous

pyrrhotite: University of California Publications in Geological Sciences Bulletin, v. 13, p. 175-252. Irwin, W.P., and Greene, R.C., 1970, Studies related to wilderness primitive areas, Agua Tibia, California: U.S.

Geological Survey Bulletin 1319-A, 19 p., scale 1:48,000.Jennings, C. W. and Bryant, William A., 2010, Fault activity map of California: California Geological Survey Geological

Data Map No. 6, scale 1:750,000.Kennedy, M.P., 1977, Recency and character of faulting along the Elsinore fault zone in southern Riverside County,

California: California Division of Mines and Geology, Special Report 131, 12 p., scale 1:24,000.http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm

Kennedy, M. P., 2011, Geologic map of the Boucher Hill 7.5' quadrangle, San Diego County California: California Geological Survey Preliminary Geologic Map website. http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm.

Kennedy, M.P., 2013, Geologic map of the Vail Lake 7.5’ quadrangle, San Diego and Riverside, Counties, California: California Geological Survey Preliminary Geologic Map website, http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm

Larsen, E. S., Jr., 1948, Batholith and associated rocks of Corona, Elsinore and San Luis Rey quadrangles, southern California: Geological Society of America Memoir 29, 182 p., plate 1, scale 1:125,000.

Matti, J. C., Cossette, P.M., and Hirschberg, D.M. , 2010, Classification of surficial materials, Inland Empire Region, southern California: Conceptual and operational framework: U.S. Geological Survey Scientific Investigations Report, in press.

Mann, J.F., 1955, Geology of a portion of the Elsinore Fault Zone California: Division of Mines and Geology Special Report 43, 22 p., scale 1:62,500.

Olmstead, F.H., 1955, Geologic map of La Jolla Indian Reservation, San Diego County, California: Unpublished geologic map, U.S. Geological Survey, Ground Water Branch, Sacramento, California, scale 1:24,000.

Pajak, A. F., III, Scott, E., and Bell, C.J., 1996, A review of the biostratigraphy of Pliocene and Pleistocene sediments in the Elsinore Fault Zone, Riverside County, California, in Bell, C.J. and Sumida, S., editors, The uses of vertebrate fossils in biostratigraphic correlation: PaleoBios, v.29, p. 28-49.

Repenning, C.A., 1987, Biochronology of the microtine rodents of the United States, in Woodburne, M.O, editor, Cenozoic mammals of north America: Geochronology and biostratigraphy: Berkeley and Los Angeles, University of California Press, p. 236-268.

Reynolds, R.E., and Reynolds, R.L., 1993, Rodents and Rabbits from the Temecula Arkose, in Reynolds, R. E. and Reynolds, J., editors, Ashes, faults and basins: San Bernardino County Museum Association Special Publication 93-1, p. 98-100.

Rogers, T.H., 1965, Santa Ana Sheet: California Division of Mines and Geology Geologic Map of California, scale 1:250,000.

Sharp, R.V., 1967, San Jacinto fault zone in the Peninsular Ranges of southern California: Geological Society of America Bulletin, v. 78, p. 705-729.

Shaw. S.E., Todd, V.R., and Grove, M., 2003, Jurassic peraluminous gneissic granites in the axial zone of the Peninsular Ranges, southern California, in Johnson, S.E., Paterson, S.R., Fletcher, J.M., Girty, G.H., Kimbrough, D.L., and Martin-Barajas, A., editors, Tectonic evolution of northwestern Mexico and southwestern USA: Boulder, Colorado, Geological Society of America Special Paper 374, p. 157-183.

Strekeisen, A.L., 1973, Plutonic rocks—classification and nomenclature recommended by the IUGS Subcommission on Systematics of Igneous Rocks: Geotimes, v. 18, pp. 26-30.

Todd, V.R., 2013 (in press), Geologic map of the Julian 7.5’ quadrangle, San Diego County, California: U.S. Geological Survey Open-File Report 94-16, scale 1:24,000.

Weber, F.H., Jr., 1963, Geology and mineral resources of San Diego County, California: California Division of Mines and Geology County Report 3, Plate 1, scale 1:120,000.

Woodburne, M. O., 1987, editor, Cenozoic mammals of north America: Geochronology and biostratigraphy: Berkeley and Los Angeles University of California Press, 336 p.

REFERENCES CITED

Geological mapping of the Aguanga 7.5’ quadrangle was conducted June 2002 - July 2003 and revised June 2013 by the Department of Conservation, California Geological Survey pursuant to the U.S. Geological Survey STATEMAP cooperative mapping award # 02HQAG0018. The quadrangle lies between 33° 22.5' and 33° 30.0' N. latitude and 116° 52.5' and 117° 00' W. longitude in the northwestern corner of the Borrego Valley 30’x 60’ quadrangle (Fig. 1). The study is aimed at providing new information for use by earth scientist, engineers, planners and developers in decision making related to long term land use planning.

Structurally the Aguanga quadrangle lies between the northwest trending, predominately right-slip San Jacinto and the parallel predominately oblique-(up to the north) right-slip Elsinore Fault Zones, two major elements of the San Andreas Fault System (Fig. 2). It is transected by the Agua Caliente Fault Zone which includes from north to south: the Lancaster-Hot Springs, Temecula Creek and Aguanga faults (Fig.2). These faults are part of a series of faults that lie sub parallel to and splay from the Elsinore Fault Zone between Lake Elsinore and Murrieta (Mann, 1955, Rogers, 1965, Kennedy, 1977). Northwest along strike the Lancaster-Hot Springs Fault appears to merge with the Murrieta Hot Springs Fault and then with the Wildomar Fault segment of the Elsinore Fault Zone (Kennedy, 1977). The Aguanga and Temecula Creek faults can be traced north to Vail Lake and either die out there or step right to the Lancaster-Hot Springs Fault (Kennedy, 2013). Southeast along strike it appears likely that the Lancaster-Hot Springs, Temecula Creek and Aguanga faults merge with the Superstition Mountain, San Felipe and Earthquake Valley faults respectively (Jennings and Bryant, 2010). Based on faulted sedimentary sequences the Agua Caliente Fault Zone has Quaternary elements, however to date there is no evidence of Holocene activity (Jennings and Bryant, 2010).

The Aguanga quadrangle is divided into two distinctive physiographic provinces by Temecula Creek and the underlying Temecula Creek Fault. Southwest of Temecula Creek lie the steep northeast facing slopes of the Palomar Mountain structural block, which rise abruptly from 2000’ near Aguanga to nearly 5000’ at Long Valley, a distance of approximately four miles. Northeast of Temecula Creek the area is underlain by rolling hills and intermountain valleys that rise and fall from nearly 2000’ at Aguanga to over 4000’ in the northeastern part of the quadrangle in the upper reaches of Tule Valley, a distance of approximately six miles.

The Palomar Mountain block is a horst being rapidly elevated by oblique slip between the Elsinore Fault Zone to the southwest and the Temecula Creek and Aguanga faults on the north (Fig. 2). The rapid uplift is evidenced by the over steepened and deeply dissected Quaternary alluvial fan deposits that mantle the slopes both here and in the adjacent Boucher Hill and Vail Lake quadrangles (Kennedy 2011, 2013). It is underlain by Mesozoic metamorphic and plutonic rock. The metamorphic rocks are Triassic and Jurassic schist, gneiss and quartzite that have been intruded by Jurassic and Cretaceous plutonic rocks of the Peninsular Ranges Batholith (PRB). The Cretaceous plutonic rocks are mostly granodiorite within the Aguanga quadrangle but become mostly tonalite to the southwest in the central part of the block at Palomar Mountain and Boucher Hill (Kennedy, 2011). The Jurassic rocks are predominately metagranitic tonalite.

The rolling hill and intermountain valleys to the northeast of Temecula Creek are underlain by Cretaceous tonalite of the Cahuilla Valley pluton of Sharp (1967). The tonalite is locally overlain by the Temecula Arkose, a coarse-grained, cross-bedded, Pliocene and Pleistocene succession of, non marine, fossiliferous, locally derived arkosic sandstone and siltstone deposits and a thin veneer of valley fill consisting of Quaternary unconsolidated alluvial deposits.

TRIASSIC-JURASSIC METASEDIMENTARY ROCKS:

The Triassic-Jurassic metasedimentary rocks (J^m) consist mostly of quartzofeldspathic schist, pelitic schist, quartzite, and metabreccia. These rocks have been informally correlated with the Julian Schist by earlier workers (Hanley, 1951; Olmstead, 1955; Irwin and Greene, 1970). The protolith of the Julian Schist, based on relic depositional structures including graded bedding and Bouma sequences, appears to be a submarine fan sequence (Germinario, 1982). The age of the Julian Schist is considered to be Triassic based on a fossil ammonite (Hudson, 1922). Gastil and others (1988) report a detrital zircon Triassic-Jurassic depositional age for the protolith. The Julian Schist can be no younger than the Middle Jurassic plutonic rocks that intrude it (Shaw and others, 2003). In addition these rocks are similar in composition and metamorphic character to parts of Larsen’s (1948) Bedford Canyon Formation which crops out immediately east of Temecula within the Santa Ana Mountains along the western side of the Elsinore Fault Zone (Kennedy, 1977).

JURASSIC METAGRANITIC ROCKS:

The Jurassic metagranitic rocks (Jmg) are gneissic and composed mostly of dark-gray, coarse- to medium-grained, foliated, biotite tonalite with lesser amounts of biotite granodiorite. The unit has intruded and assimilated “Julian Schist” and is characterized by elongated remnant inclusions of it. These inclusions range in size from an inch or so to more than 30 feet and have their long axis in the foliation plane. These rocks are correlated with the granodiorite of Harper Creek mapped in the Julian area by Todd (2013). They are described in detail and assigned a Middle Jurassic (U-Pb) age of 170-160 Ma by Shaw and others (2003).

CRETACEOUS GRANITIC ROCKS:

The Cretaceous granitic rocks are based on the classification of Streckeisen (1973), see Fig. 3. They include the tonalite of the Coahuila Valley pluton, (Ktc), granodiorite (Kgd), and tonalite (Kt).

Tonalite of the Cahuill Valley Pluton (Ktc) crops out northeast of the Temecula Creek Fault. It consists mostly of light gray, coarse grained, relatively homogeneous hornblende-biotite tonalite. Sphene is a conspicuous accessory mineral occurring as large, honey-colored euhedral crystals. Other accessory minerals include epidote (pistacite and allanite), zircon, apatite, tourmaline, and opaque minerals. These rocks were described in detail by Sharp (1967) and are part of his Cahuilla Valley pluton.

Granodiorite (Kgd) crops out southwest of the Temecula Creek Fault. These rocks were originally described within the Vail Lake quadrangle by Irwin and Greene (1970) and correlated with the Woodson Mountain Granodiorite of Larsen (1948). Rounded masses of light-colored granodiorite are common on ridge crest and slopes, and many of these appear to be residual boulders lying on deeply weathered parent rock. Though they are mostly granodiorite approximately 15 - 20 percent are tonalite and as much as another 5 -10 percent are granite and quartz monzonite. The rock is light-gray to white, coarse- to very coarse-grained hornblende-biotite granodiorite and has a weak foliation marked by the planar oriented biotite.

Tonalite (Kt) crops out southwest of Temecula Creek at the Riverside-San Diego County line and south of the Aguanga Fault along the southern border of the quadrangle. They are typically massive, medium- to coarse-grained, light-gray, hornblende-biotite tonalite and in lesser amounts granodiorite and monzogranite. The contacts between tonalite and granodiorite are gradational and therefore only approximate. In large part these rocks are lithologically similar to and tentatively correlated with rocks 30 miles (50 km) to the southeast within the Julian quadrangle where they were described in detail, assigned a zircon U-Pb isotopic age of 90 – 100 Ma and given the informal name “tonalite of Granite Mountain” (Todd, 2013). Like the Jurassic plutons, they intrude Julian Schist and are locally characterized by remnant inclusions of it.

PLIOCENE AND PLEISTOCENE SEDIMENTARY ROCKS:

The Temecula Arkose of Mann, (1955) has been subdivided into two informal parts in this study which include a lower part (Ttl) that consists of white and very light-gray, poorly-sorted, coarse- and medium-grained, moderately well indurated, but, locally friable, cross-bedded arkosic sandstone and an upper part (Ttu) that consists of pale- to dark-yellowish-brown and olive-gray, fine- medium- and coarse- grained sandstone, siltstone and claystone. The formation is labeled Tt where the upper and lower parts are not divided. The Temecula Arkose contains several prominent, yellowish-gray tuffs, most of which occur in the “upper part” of the formation. The Temecula Arkose has a total combined thickness measured in sections east of Aguanga in the Vail Lake and Pechanga quadrangles of more than 600’ (Kennedy, 2013). The total thickness within the Aguanga quadrangle is approximately 500’. The Temecula Arkose has an early Pliocene through late Pliocene age (~ 1.9 – 4.6 Ma) based on fossil

GEOLOGIC SUMMARY

PLIOCENE AND PLEISTOCENE SEDIMENTARY ROCKS (CONTINUED):

vertebrate assemblages from Temecula, Radec, Vail Lake and Butterfield Valley (Golz and others, 1977; Kennedy, 1977; Reynolds and Reynolds, 1993; Pajak and others, 1996). Kennedy (1977) assigned the unit a late Pliocene Blancan 1V-V mammal age (2.2 to 2.8 Ma) based on vertebrate assemblages collected east of the quadrangle. Assemblages include Nannippus, Hypolagus, Tetrameryx, Equus, and Odocoileus (Golz and others, 1977). Later work established the first occurrence of Tetrameryx as Irvingtoninan 1 rather than late Blancan (Woodburne, 1987), placing the Temecula Arkose age nearer 1.9 Ma than 2.2 Ma. In addition, a microtine fauna from this unit in the Radec area was reported to have an age of 4.6 Ma (Blancan 1) (Repenning, 1987) which would suggest a depositional period that extended from early Pliocene into the lower Pleistocene.

QUATERNARY SURFICIAL DEPOSITS:

The classification of the Quaternary sedimentary deposits is modified from the U.S. Geological Survey, Classification of surficial materials, inland empire region, southern California: Conceptual and operational framework, described by Matti and others (2010). Inherent to this classification is the fact that the surficial deposits have been deposited continuously, albeit at different rates, throughout the Quaternary Period and each of the basic lithostratigaphic units mapped (alluvial fan and alluvial valley fill) represent often interfingered time transgressive facies. The parameters used in this modified classification include : 1) physical properties and lithologic features, e.g. consolidation, induration, fabric, grain size, sorting, etc., 2) genesis and geomorphic setting, e.g. alluvial fan, alluvial valley fill deposits) and 3) age determinations, e.g. radiometric analyses, paleontology, pedogenic soil characteristics, desert varnish, vegetation, degree of incision, etc.

Surficial Quaternary units include:

1). “Modern surficial deposits” which are those being deposited actively or intermittently active over the past few hundred years. Their soil development is slight to non-existent. They are labeled Qa, ( alluvial valley fill deposits). 2). “Young surficial deposits” which are those that were deposited during the Holocene and latest Pleistocene or since the Holocene-to-Pleistocene climatic transition (Bull, 1991). They are slightly dissected, have slight soil development, and little if any pavement or varnish. They are labeled Qya (young alluvial valley fill deposits). 3). “Old surficial deposits” which are those that were deposited during the middle to late Pleistocene and spanning the period of approximately 500ka to about 15ka. They have moderately dissected surfaces, good soil development, minor clay films, and moderate varnish and pavement. They are labeled Qoa (old alluvial valley fill deposits).4). “Very old surficial deposits” which are those that were deposited during the early to middle Pleistocene or approximately 1 Ma to 500ka. They have well dissected surfaces, strong soil development, thick clay films and well developed varnish and pavement. They are labeled Qvof (very old alluvial fan deposits) and Qvoa (very old alluvial valley fill deposits).

ACKNOWLEDGEMENT OF PREVIOUS GEOLOGIC MAPPING:

Bedrock contacts and faults in the mountainous southwestern part of the quadrangle are in part modified from Weber (1963), Rogers (1965) and unpublished 1964, 1:24,000 reconnaissance mapping by F. Harold Weber and T.H. Rogers. Geological mapping within the sedimentary succession in the vicinity of Vail Lake by J. F. Mann (1955) proved very useful in developing a better understanding of the Plio-Pleistocene stratigraphy of the area. Modifications of all earlier work was based on new mapping and observations made from large scale stereo air photography including USDA 1953 (scale 1:24,000) and Riverside County, 1990 (scale 1:24,000) as well as from Google Earth imagery.

Figure 3 - Map showing the location of the Vail Lake, Aguanga Palomar Observatory and Boucher Hill 7.5’ quadrangles with respect to the Elsinore, Agua Caliente and San Jacinto fault zones.

EXPLANATIONFault-- dashed where inferred

116° 15'

33° 30'

33° 15'

116° 15'117° 00'

33° 15'

33° 30'

117° 00'

Aguanga 7.5' quadrangle

Palomar Obs. 7.5' quadrangle

Vail Lake 7.5' quadrangle

Boucher Hill 7.5' quadrangle

San

Jacinto

FaultZone

Hot Springs

Fault

Temecula

Creek

Fault

Agua Tibia- Palomar Mt. Block

Fault

Zone

Lake Henshaw

Elsinore

Murrieta Hot Springs-Lancaster-

Agua

Caliente

Fault

Zone

Vail Lake Trough

Aguanga

Fault

Borrego Valley 1:100,000-scale Quadrangle

Miles0 10 20 30

Aguanga Beauty Mt. Bucksnort Mt. Collins Valley Clark Lake Rabbit Pk. Oasis

Boucher Hill PalomarObservatory

Borrego Springs Hot Springs Mt. Borrego Palm Canyon

Clark Lake Fonts Point SeventeenPalms

Rodriquez Mt. Mesa Grande Warners Ranch Ranchita Tubb Canyon Borrego Sink Borrego Mt. Shell Reef

Ramona Santa Ysabel Julian EarthquakeValley

Whale Peak Harper Canyon Borrego Mt. S.E.

Vail Lake

Figure 2 - Index map showing the location of the Aguanga and other 7.5' quadrangles in the Borrego Valley 1:100,000-scale quadrangle.

CGS

OFR 96-06

&

CD 2000

-008

San Pasqual

FY 2002-03 FY 2005-06 FY 2006-07

Mapping completed under STATEMAP

Revised 2014

Revised 2014Revised 2014

N

QuartzSyenite

QuartzMonzonite

QuartzMonzodiorite

Syenite Monzonite Monzodiorite

Granite

Alka

li-feld

spar

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

Figure 1 - Classification of plutonic rock types (Streckeisen, 1973).A - alkali feldspar; P - plagioclase feldspar; Q - quartz.

JURASSIC

CENOZOIC

MESOZOIC

Holocene

Pleistocene

Pliocene

QUATERNARY

TERTIARY

CRETACEOUS

CORRELATION OF MAP UNITS

TRIASSIC

Qa

Qya

Qoa

QvoaQvof

Qa+Qya

Tt

Ttu

Ttl

Kgd Kt

Jmg

KtcKtc-w

J^m

UD

Contact - Contact between geologic units; dashed where approximately located; dotted where concealed.

Fault - Solid where accurately located; dashed where approximately located; dotted where concealed; U = upthrown block, D = downthrown block; arrow and number indicate direction and angle of dip of fault plane; tildes (~~) indicate sheared rock; queries indicate uncertainty.

Zone of intense shearing

Strike and dip of sedimentary beds:

Inclined

Strike and dip of foliation in metamorphic rock: Inclined Vertical

Strike and dip of joints: Inclined Vertical

55

55

27

25

MAP SYMBOLS

?

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

MODERN SURFICIAL DEPOSITSSediment that has been recently transported and deposited in channels and washes, on surfaces

of alluvial fans and alluvial plains, and on hill slopes and in artificial fills. Soil-profile development is non-existant. Includes:

Alluvial flood plain deposits (late Holocene) - Active and recently active alluvial deposits along canyon floors. Consists of unconsolidated sandy, silty, or clay-bearing alluvium. Does not include alluvial fan deposits at distal ends of channels.

YOUNG SURFICIAL DEPOSITSSedimentary units that are slightly consolidated to cemented and slightly to moderately dissected.

Alluvial fan deposits typically have high coarse-fine clast ratios. Young surficial units have upper surfaces that are capped by slight 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.

Active alluvial flood plain and young alluvial flood plain deposits undivided (late Holocene and Pleistocene) - See descriptions of individual deposits.

OLD SURFICIAL DEPOSITSSediments that are moderately consolidated and slightly to moderately dissected. Older surficial

deposits have upper surfaces that are capped by moderate to well-developed pedogenic soils. Includes:

Old alluvial flood plain deposits undivided (late to middle Pleistocene) - Fluvial sediments deposited on canyon floors. Consists of moderately well consolidated, poorly-sorted, permeable, commonly slightly dissected gravel, sand, silt, and clay-bearing alluvium.

VERY OLD SURFICIAL DEPOSITSSediments that are slightly to well consolidated to indurated, and moderately to well dissected,

Upper surfaces are capped by moderate to well-developed pedogenic soils. Includes:

Very old alluvial fan deposits (middle to early Pleistocene) - Mostly well-dissected, well-indurated, reddish-brown sand and gravel alluvial fan deposits.

Very old alluvial flood plain deposits undivided (middle to early Pleistocene) - Fluvial sediments deposited on canyon floors. Consists of moderately to well-indurated, reddish-brown, mostly very dissected gravel, sand, silt, and clay-bearing alluvium.

SEDIMENTARY ROCKS

Temecula Arkose (early to late Pliocene) - The Temecula Arkose is here subdivided into two informal parts. A lower part (Ttl) that consists of white and very light-gray, poorly-sorted, coarse- and medium-grained, moderately well indurated, but, locally friable, cross-bedded arkosic sandstone and an upper part (Ttu) that consists of pale yellowish-brown, olive-gray, dark-yellowish-brown, fine-, medium- and coarse-grained sandstone, siltstone and claystone. The formation is labeled Tt where the upper and lower parts are not divided. The Temecula Arkose contains several prominent, yellowish-gray tuffs, most of which occur in the "upper part" of the formation. See description in Geologic Summary for more detail.

PLUTONIC ROCKS (See Figure 1 for classification)

Granodiorite and hybrid granitic rocks undivided (mid-Cretaceous) - Mostly deeply weathered, medium- to coarse-grained, hornblende-biotite granodiorite. Also includes a wide variety of hybrid granitic rocks. In addition some assemblages include large proportions of schist and gneiss.

Tonalite of the Cahuill Valley Pluton (mid-Cretaceous) - Light-gray, coarse-grained, relatively homogenous, hornblende-biotite tonalite. Ktc-w - deeply weathered Ktc.

Tonalite (mid-Cretaceous) - Light-gray, massive, medium- to coarse-grained, hornblende-biotite tonalite.

METAMORPHIC ROCKS

Metagranitic rocks (Jurassic) - Mostly dark-gray, coarse- to medium-grained, foliated, biotite tonalite with lesser amounts of biotite granite.

Metasedimentary rocks (Jurassic and Triassic) - Mostly quartzofeldspathic schist, pelitic schist, quartzite, and metabreccia.

DESCRIPTION OF MAP UNITS

Qa

Qya

Qoa

Qvof

Qvoa

Kgd

Kt

Qa+Qya

Jmg

TtTtu

Ttl

Ktc

Ktc-w

J^m

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