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**Preliminary Digital Geologic Map of the Santa Ana 30´ X 60´
Quadrangle, southern California, version 2.0**

Compiled by D.M. Morton^1^

Version 2.0 digital preparation by Kelly R. Bovard^1^ and Rachel M.
Alvarez^1^ -- 2004

Version 1.0 digital preparation by Rachel M. Hauser^1^ and Kelly R.
Ruppert^1^ -- 1999

^1^Western Surficial Processes Team

U.S. Geological Survey

Department of Earth Sciences, University of California, Riverside,
California

Open-File Report 99-172

Version 2.0 - 2004

*SCAMP---Southern California Areal Mapping Project*

A geologic-mapping project sponsored jointly by the U.S.

Geological Survey and the California Geological Survey

![](media/image2.jpeg){width="6.141666666666667in" height="1.375in"}

U.S. Department of the Interior

U.S. Geological Survey

Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the U. S. Government.

**PRELIMINARY DIGITAL GEOLOGIC MAP OF THE**

30' X 60' SANTA ANA QUADRANGLE, VERSION 2.0

# Geologic setting

The Santa Ana Quadrangle is in the northern part of the Peninsular
Ranges Province as defined by Jahns (1954). The quadrangle is underlain
by rocks characteristic of the eastern part of the province except for
the northeast corner, which is underlain by basement rocks of the
Transverse Ranges Province. A summary of the general geology of the
Peninsular Ranges Province is given by Jahns (1954) and a generalized
geologic map of this part of the Peninsular Ranges Province is given by
Rogers (1965).

Physiographically, the northern part of the Peninsular Ranges Province
is divided into three major, fault-bounded blocks, the Santa Ana
Mountains, Perris, and San Jacinto Mountains. The Santa Ana Mountains
block is the westernmost of the three, extending eastward from the coast
to the Elsinore fault zone. Tertiary sedimentary rocks ranging in age
from Paleocene through Pliocene underlie most of the western part of the
Santa Ana block. East of these Tertiary rocks, in the Santa Ana
Mountains, a highly faulted anticlinal structure, is cored by a basement
assemblage of Mesozoic metasedimentary and Cretaceous volcanic and
batholithic rocks. Overlying this basement is a thick section of
primarily upper Cretaceous marine rocks, and Paleogene marine and
nonmarine rocks. In the southern part of the Santa Ana Mountains the
anticlinal nature of the mountains passes into extensive, nearly
horizontal erosional surface that is partly covered by Miocene basalt
flows.

North of the Santa Ana Mountains block, the relatively low Puente Hills
are underlain principally by folded and faulted Neogene marine
sedimentary rocks of the Los Angeles basin (e.g., Yerkes and others,
1965). Up to 8,200 m of middle and late Miocene age rocks are exposed in
the Puente Hills, strata equivalent to those from which most of the
petroleum of the Los Angeles basin has been produced (Durham and Yerkes,
1964; Yerkes, 1972). Located between the Puente Hills and the Santa Ana
Mountains are several anticlinal structures exposing marine Pleistocene
strata (Yerkes, 1972).

East of the Santa Ana block and west of the San Jacinto fault zone is
the Perris block, a roughly rectangular area of relatively low relief,
that has remained relatively stable and undeformed during the Neogene.
The Perris block is underlain by lithologically diverse prebatholithic
metasedimentary rocks intruded by plutons of the Cretaceous Peninsular
Ranges batholith. Supra-batholithic volcanic rocks are preserved in the
western part of the block. Several erosional and depositional surfaces
are developed on the Perris block (e.g., Dudley, 1936; Woodford and
others, 1971) and thin to relatively thick sections of nonmarine, mainly
Quaternary sediments discontinuously cover the basement. The older
surfaces are of probable Paleogene age and there is suggestive evidence
that Paleogene sedimentary deposits once covered at least the western
part of the block.

The San Jacinto Mountains block lies east of the Perris block, but only
the northern part of it extends into the Santa Ana quadrangle. A thick
section of Miocene through Pleistocene nonmarine sedimentary rocks
underlies most of the northern San Jacinto Mountains block allowing
limited granitic and metamorphic rocks to show through only in the
southern part of the quadrangle.

##### Summary of major structural elements

## Faults

Northwest-striking faults of the active San Jacinto (Allen, 1981) and
Elsinore (Hull and Nicholson, 1992; Langenkamp and Combs, 1974) fault
zones dominate the neotectonic structure of the quadrangle. Both fault
zones consist of en echelon faults that have formed extensional basins
(Hull, 1990; Kennedy, 1977; Morton and Matti, 1993; Sharp, 1967; Weber,
1976).

The northern part of the San Jacinto structural basin, in the southeast
corner of the quadrangle, formed at a right step between the Claremont
fault on the east and the Casa Loma fault on the west. The San Jacinto
structural basin is the site of rapid subsidence, both tectonic and due
to groundwater withdrawal (e.g., Morton, 1977; Proctor, 1962), and
contains Quaternary sediments estimated to be about 3000 m thick (Fett,
1968). Both faults are considered to be the source of major earthquakes
in the early part of the 20^th^ century.

The Elsinore fault zone consists of a complex assemblage of
right-stepping and left-stepping en echelon faults. Movements on these
faults have produced a series of extensional basins, which in aggregate
result in an elongate, composite, structural trough. The trough includes
numerous minor compressional uplifted domains (Hull, 1990; Kennedy,
1977; Weber, 1976), some of which separate the constituent extensional
basins. The largest of these extensional basins, the Elsinore structural
basin, is largely filled by Elsinore Lake.

# Quaternary sedimentary deposits

Quaternary deposits are dominated by nonmarine fluvial deposits except
in the coastal area where marine deposits are abundant, and near the
Whittier Fault where early Pleistocene marine deposits are exposed in
anticlinal structures. Most of the Quaternary nonmarine deposits
originated in the drainage basin of the Santa Ana River, which includes
most of the area covered by the Santa Ana quadrangle. Because of its
unique structural origin, the Santa Jacinto sub-basin is considered
separately from rest of the Santa Ana basin in this report.

That part of the Santa Ana River basin (excluding the San Jacinto
sub-basin) within the quadrangle consists of three distinct reaches. The
broad alluvial valley east of the Puente Hills and northern Santa Ana
Mountains forms an upper reach. A central reach is defined by the
narrow-floored Santa Ana Canyon, and the broad, complex, alluvial fan
below Santa Ana Canyon makes up the third reach.

The valley area upstream from Santa Ana Canyon is flanked by Holocene
and Pleistocene alluvial fan deposits with intervening valley and
channel fluvial deposits, with a relatively narrow belt of Quaternary
alluvium. Holocene and Pleistocene alluvial fan deposits with
intervening valley and channel fluvial deposits flank the valley area
upstream from Santa Ana Canyon. The third reach is a broad, complex
alluvial fan below Santa Ana Canyon. This lower alluvial fan reach is a
low-gradient, broad sandy fan that merges with marine deposits near the
coast. Differentiation of deposits of the alluvial fan, now largely
covered by asphalt, concrete, and yards, is based in part on the soil
map of Eckmann and others (1919).

The San Jacinto River sub-basin is a major tributary of the Santa Ana
River. The source area of the river is in the San Jacinto Mountains east
of the quadrangle and terminates at Lake Elsinore. During most of the
Quaternary, the greater part of the sediment derived from the San
Jacinto Mountains was deposited in the southern and central part of the
San Jacinto structural basin where the rate of sedimentation effectively
balances the rate of subsidence. In the northern part of the basin (SE
corner of the quadrangle), subsidence rates exceed sedimentation rates
resulting in a closed depression periodically filling with water to form
ephemeral Mystic Lake. The very low river gradient westward from Mystic
Lake forms a broad fluvial plain. The river exits the Perris block
though the narrow Railroad Canyon cut into basement rocks. The river
terminates at the Elsinore structural basin, a closed depression filled
by Lake Elsinore. Several times during the 20^th^ century Lake Elsinore
has filled and overflowed northward along the Elsinore fault zone along
Temescal Creek to join the Santa Ana River at Corona.

Along the coast of southern California are a large number of Quaternary
and late Pliocene marine terrace deposits resulting from tectonic uplift
of coastal southern California. Building on earlier work, published and
unpublished mapping by Kern and coworkers has led to the recognition of
28 marine terraces that range in age from less than 80,000 to 3,090,000
years and range in elevation from 5-6 m to 408-413 m (Kern, 1996, Kern
and others, 1996, and unpublished mapping). In the Santa Ana 30'x60'
quadrangle Kern has mapped six of the youngest eight terraces that range
in age from 80,000 to 450,000 years and undifferentiated older
terrace(s). These terraces, labeled Qop~1~, Qop~2~, Qop~3~, Qop~4~,
Qop~6~, Qop~7~ and Qvop on the map, are thin marine deposits on abrasion
platforms produced in the intertidal and shallow subtidal zones.
Generally the marine deposits are overlain by non-marine sediments.

###### Quaternary-Tertiary deposits

Deposits spanning the early Quaternary and late Tertiary includes
widespread sandstone and conglomerate that underlies the Pauba Formation
in the Wildomar area. Also included are a few small, isolated remnants
of conglomerate and gravely sand in the Riverside-Norco areas. A thick
sequence of Plio-Pleistocene continental deposits underlies the San
Timoteo Badlands, at the north end of the San Jacinto block that overlie
the Pliocene and Miocene Mount Eden formation.

# Neogene deposits

# 

# Neogene sedimentary deposits are dominated by thick sections of marine Miocene and Pliocene strata of the Los Angeles basin (e.g., Woodford and others, 1946; Schoellhamer and others, 1981; Yerkes and others, 1965; Durham and Yerkes, 1964; Yerkes, 1972) and the San Joaquin Hills (Morton and Miller, 1981; Vedder 1972). Marine strata extended into the northern end of the Elsinore fault zone south of Corona (Gray,1961) and east onto Cretaceous granitic rocks in the Norco area (Morton and Matti, 1989). Inland, in addition to the Pliocene and Miocene sedimentary rocks of the San Timoteo Badlands, Pliocene strata were deposited in the Temecula area. In the vicinity of Lake Mathews are remnants of additional fluvial and lacustrine Miocene strata. 

Initial subsidence of the Los Angeles basin occurred in the middle
Miocene, and was followed closely by the main phase of subsidence during
the upper Miocene and early Pliocene; basin closing occurred primarily
during the Pleistocene (Yerkes and others, 1965). Most of the oil from
this prolific basin (over 6 billion barrels estimated ultimate recovery)
is from late Miocene and early Pliocene strata (Yerkes and others,
1965). The southern part of the central block and the southeastern part
of the northeastern block of the Los Angeles Tertiary basin are included
within the Santa Ana quadrangle (Yerkes and others, 1965).

At the south end of the central block, in the San Joaquin Hills area,
widespread middle Miocene Topanga Formation\* is overlain by the San
Onofre Breccia, which is in turn overlain by the Miocene and early
Pliocene Capistrano Formation. The San Onofre Breccia was derived from
blueschist metamorphic rocks, which Woodford (1925) demonstrated had an
offshore provenance. Further north, in the Puente Hills area, the
Topanga Formation has a thickness in excess of 480 m (Yerkes, 1972), but
is dwarfed by the 4,000+ m aggregate thickness of the overlying Miocene
and early Pliocene Puente Formation. The Puente Formation is succeeded
by as much as 1,825 m of marine Pliocene Fernando Formation (Yerkes,
1972); a total of over 6,300 m of sedimentary rock deposited in a time
period spanning only parts of the Miocene and Pliocene.

\* Although the Topanga Formation in the Santa Monica Mountains was
elevated by Yerkes and Campbell (1979) to Group rank with three
formations, the Topanga Canyon (with four members), Conejo Volcanics,
and the Calabasas. The Topanga Formation, with three members in the
Santa Ana 30'x 60' quadrangle, has not been correlated with any of units
recognized by Yerkes and Campbell. Until the Topanga nomenclature is
resolved for areas beyond the Santa Monica Mountains, the existing
Topanga Formation nomenclature will be used for the Santa Ana
quadrangle.

Basalt volcanism occurred in the Elsinore-Temecula area between 7 and 12
My. Older, more silicic mid-Miocene volcanism occurred in the El Modena
and San Joaquin Hills area. Volcanics in the El Modena area are of
andesitic basalt and andesitic composition (Yerkes, 1957). In the San
Joaquin Hills area are large numbers of andesitic and diabasic
intrusives (Vedder, 1975). The El Modeno volcanism is part of widespread
mid-Miocene volcanism in the Los Angeles basin area (Shelton, 1955).

## Paleogene deposits

Remnants of the extensive package of marine and nonmarine Sespe and
Vaqueros Formations of Eocene to early Miocene age are widespread on the
west side of the Santa Ana Mountains. Eocene conglomerate and sandstone
contains an assemblage of silicic welded tuff, all of which appear to be
exotic to southern California (Woodford and others, 1968, 1973). Marine
and nonmarine Paleocene deposition occurred during a time of extreme
weathering of both pre-Paleocene basement rocks and the Paleocene
sedimentary rocks.

## Mesozoic rocks

## Sedimentary rocks

Upper Cretaceous sedimentary rocks were first recognized in the Santa
Ana Mountains by the California Geological Survey before 1865 (Whitney,
1865). These rocks were later included with the Chico Formation of
northern California by Packard (in Dickerson, 1914, p. 262-263) where it
was subdivided into six units. The upper unit was later determined to be
of Paleocene age. In the Santa Ana Mountains, Packard (1916, 1922) named
the basal conglomerate unit the Trabuco Formation and grouped the
remaining rocks into the Ladd Formation and the Williams Formation.
Popenoe (1942), Woodring and Popenoe (1942, 1945), Schoellhamer and
others (1954), and Morton and Baird (1976) modified Packard's
nomenclature. In current usage the nomenclature of the Upper Cretaceous
rocks is in descending order Williams Formation that includes the
Pleasants Sandstone Member, Schulz Ranch Member, and the Starr Member;
the Ladd Formation that includes the Holz Shale Member and the Baker
Canyon Conglomerate Member; and the basal Trabuco Formation.

## Peninsular Ranges batholith

The eastern part of the Santa Ana quadrangle is dominated by rocks of
the Cretaceous-age Peninsular Ranges batholith. The batholith extends
from just north of the Santa Ana quadrangle several hundred miles south
(e.g., Larsen, 1948; Silver and Chappel, 1988; Todd and others, 1988).
Early descriptions of parts of the batholith in the Santa Ana quadrangle
included Dudley (1935), Engel(1959), Miller (1946), and Osborn (1939).
The first major synthesis was by Larsen (1948), who conducted field work
within the batholith discontinuously from 1906 to 1938. More recent
investigations included within the Santa Ana quadrangle have largely
centered on topical investigations (e.g., Baird and others, 1974, 1979;
Baird and Miesch, 1984; Gromet and Silver, 1987; Krummenacher and
others, 1975; Premo and others, 1998; Silver and Chappel, 1988) and
investigations of individual plutons (Miesch and Morton, 1977; Morton,
1969; Morton and Baird, 1976; Morton and others, 1969).

The Peninsular Ranges batholith has been variously subdivided into
longitudinal zones (Baird and Miesch, 1984; Baird and others, 1974,
1979; Silver and Chappel, 1988, Gromet and Silver, 1987; and Todd and
others, 1988). Based upon initial strontium and lithologic criteria.
Morton and Kistler (1997) subdivided the northern part of the batholith
into four major zones; the western two subdivisions are present in the
Santa Ana quadrangle. Of these two, a western zone consists of
high-level (shallow) plutons and an eastern zone consists of moderate to
deeply exposed plutons. Plutons within the western zone typically
consist of massive textured rock containing equant shaped mafic
inclusions, having sharp contacts with their wall rocks, and have sparse
or are devoid of foliation and/or layering. Pressures of crystallization
range from 2-3 Kb (Smith and others, 1991), and emplacement ages range
from 126-110 Ma (Premo and others, 1998). The eastern zone plutons have
well-developed planar fabric (foliation) containing discoidal to
pancake-shaped mafic inclusions, and lack sharp contacts with wall
rocks. Pressures of crystallization range from 4.5 - 6.5 Kb (Smith and
others, 1991) and emplacement ages range from 98 to 106 Ma (Premo and
others, 1998). Emplacement ages appear to systematically decrease in age
from west to east across both zones (Premo and others, 1998). U/Pb ages
from zircons are considered to be emplacement ages. U/Pb ages for a
selected number of granitic rocks have recently been determined for
rocks in the Santa Ana quadrangle (Premo and others, 1998).

An extensive strontium and rubidium isotopic database of R.W. Kistler
shows the granitic rocks in the western zone have initial Sr values of
0.7036 to 0.7045 indicating only moderate continental crust component
(Morton and Kistler, 1997; Kistler, and others, 2003). The rocks of the
zone to the east generally have initial Sr values of 0.7045 to 0.7055
indicating a larger continental crust component. Rocks in the eastern
two zones have yet larger initial Sr, 0.706-0.708 values. Variation in
initial Sm values is in accord with the Sr ratios (Premo and others,
1998).

The description of discrete and/or recognizable batholith units is in
order of their known or inferred age of emplacement -- youngest to
oldest. Generalized (generic) units are non-discrete pluton forming
units, are time transgressive, and are here treated as undifferentiated
or undivided units.

Isotopic ages referred to in the rock unit descriptions are from W.R
Premo and L.W. Snee (Premo and others, 1998 and per. commun., 1999).
Pb/U ages are interpreted as emplacement age of the granitic rock and
the ^40^Ar/^39^Ar ages of hornblende, biotite, and potassium feldspar
progressive cooling ages.

**Volcanic and hypabyssal rocks**

A large area of the Santa Ana Mountains and the western part of the
adjacent Perris block are underlain by an assemblage of Cretaceous age
volcanic and shallow intrusive rocks. Considerable amounts of these
volcanic rocks include volcaniclastic and sedimentary rocks. The rocks
in the Santa Ana Mountains termed the Santiago Peak volcanics rest
uncomformably on the Bedford Canyon and related rocks, and range from
basaltic andesite to rhyolite. Included in the Santa Ana block volcanic
assemblage is a small serpentine body and associated carbonate-silicate
rock. Volcanic rocks of the Perris block are overall more silicic than
those of the Santa Ana Mountains block.

Descriptions of these volcanic rocks suggested they had been subject to
low grade metamorphism. Herzig (1991) has made a recent and thorough
examination of the Santiago Peak volcanics. Zircon ages from these
volcanic rocks indicate they are coeval with granitic rocks of the
Peninsular Ranges batholith (Anderson, 1991). Herzig (1991) linked
mineral assemblages, previously considered being of regional low grade
metamorphism, to hydrothermal activity associated with volcanism.
Sedimentary rocks interbedded with volcanic rocks correlated with the
Santiago Peak volcanics in San Diego County have yielded Late Jurassic
fossils (Fife and others, 1967).

**Metamorphic rocks**

There is a long and convoluted history to the terminology of the
metamorphic rocks in the Santa Ana quadrangle. In the Santa Ana
Mountains, the name "Santa Ana" was used by Smith (1898) for limestone
within the prebatholithic sedimentary rocks of very low metamorphic
grade and later used "Santa Ana Slates" (Smith, 1914), a name retained
by Engel (1959). Merrill (1914) referred to the metamorphic rocks as the
"Santa Ana metamorphic strata". Larsen (1948) used the name Bedford
Canyon Formation for exposures of these rocks in Bedford Canyon in the
northern Santa Ana Mountains. Smith on the basis of *Rhynchonella sp*
assigned a Triassic age to the limestone*.* Later fossil collections
from the northern Santa Ana Mountains were concluded to be of Jurassic
age (Imlay, 1963; 1964; 1980; Silberling and others, 1961). The rocks in
the area of Bedford Canyon generally appear as well indurated
sedimentary rocks with a variety of sedimentary structures such as
ripple marks and cross-bedding.

In the northern Perris block the prebatholithic rocks were termed the
Elsinore metamorphics by Dudley (1935). Larsen (1948) extended the
Bedford Canyon Formation south and east from the Santa Ana Mountains to
the Perris block in the vicinity of Domenigoni and Auld Valleys. Larsen
noted differences in the lithology of the rocks of the Perris block from
those of the Santa Ana Mountains. East of Domenigoni Valley Larsen
termed the metamorphic rocks "Paleozoic schists and quartzites". The age
designation was based upon a report of a Mississippian coral (Webb,
1939) that was characterized by Larsen (1948, p. 16) as being from
schist "which contain limestone beds from which Webb (1939) has
described Mississippian fossils." Schwarcz (1969) has clearly shown the
single coral specimen found as "float", could not have originated where
it was found.

In the Winchester area Schwarcz (1969) retained Larsen's usage of the
Bedford Canyon, while noting the lithologic difference with the Bedford
Canyon formation in the Santa Ana Mountains. Schwarcz (1969) renamed the
"Paleozoic schists and quartzites" the French Valley formation after
exposures in the area of French Valley. Schwarcz considered the French
Valley Formation to be of Mesozoic age stating "The French valley
Formation interfingers with the Bedford Canyon Formation at their
contact" (Schwarcz, 1969, p. 22). Schwarcz described within his French
Valley formation a remarkable metamorphic gradient increasing from low
grade to high amphibolite grade over a distance of about three
kilometers. Schwarcz interpreted the metamorphic facies to be a low
pressure, high temperature Buchan type. Later Morton (1993) divided the
French Valley formation of Schwarcz into a western Mesozoic age
assemblage and an eastern assemblage of probable Paleozoic age. The
western assemblage Morton included Larsen's Bedford Canyon formation.
The eastern package, based only on lithologic similarities was
considered probably to be correlative with Paleozoic rocks to the south
and east in the Peninsular Ranges. Morton (1993) concluded the
Paleozoic(?) and Mesozoic rocks had been structurally juxtaposed along a
major suture. At the time of juxtapositioning the Paleozoic(?) rocks
were at an elevated temperature (upper amphibolite facies) and the
Mesozoic rocks at much lower temperatures. Juxtapositioning resulted in
thermal metamorphism of the adjacent Mesozoic rocks described by
Schwarcz (1969).

In 1966 M.A. Murphy collected some poorly preserved and deformed fossils
from a calc-silicate outcrop within the Mesozoic rocks east of Sun City,
Romoland quadrangle. Included were large crinoid stems and pelycepods.
Murphy sent a latex impression of a pelycepod to E.C. Allison, who in
turn sent the impression to G.E.G. Westermann for identification.
Westermann ( per. commun. to E.C. Allison dated 10/16/68) stated "This
is a poorly preserved, obviously distorted specimen which cannot be
identified at the generic or specific level. I dare only the following:

"Right valve of the Bivalvia family Aviculepectinidae; possible ??
*Claraia* ex. gr. *C. himaica* (Bittner) and *C.*(?) *occidentalis*
(Whiteaves) which would be late Lower Triassic. However, almost any age
within the Triassic or even Permian is possible."

Original sedimentary features are preserved within strata in the Bedford
Canyon Formation in the northern Santa Ana Mountains (e.g., Gray, 1961;
Schoellhamer and others, 1981). South and east from Bedford Canyon
original sedimentary structures are progressively obliterated by
structural transposition. Just east of the Elsinore fault zone few
original sedimentary bedding (S~0~) remain. In the vicinity of Railroad
Lake essentially all bedding is structurally transposed into a 1^st^
generation mechanical layering, S~1~. In the western part of Domenigoni
Valley area the 1^st^ generation layering has been folded and
progressively eastward transposed into 2^nd^ generation mechanical
layering, S~2~. Further east towards the suture the 2^nd^ generation
layering is progressively transposed into a 3^rd^ generation layering,
S~3~, which apparently was produced by deformation accompanying the
suturing. In the area of the suture only S~3~ is present. East of the
suture S~3~ transposes an older compositional layering of the
Paleozoic(?) rocks. S~3~ diminishes in intensity eastward with only the
older gneissic layering at the eastern edge of the Santa Ana quadrangle.

Here the name Bedford Canyon Formation is restricted to the vicinity of
Bedford Canyon in the northern Santa Ana Mountains. Pre-batholithic
rocks else where are not assigned formal name but are given designations
based upon their principal composition.

##### Notes regarding features and conventions used in the map

##### and database of the Santa Ana 30' X 60' quadrangle

1\. A question mark (?) attached to a unit label in the database
indicates that the identity of the map unit at that particular place is
uncertain.

2\. Units that are submerged below the present day water level of Lake
Perris are designated by a unit label that is followed by the letter (s)
in parentheses.

3\. Subscripts used for relative age subdivisions of some Quaternary
deposits designate decreasing age by increasing numbers, e.g. Qyf~4~ is
younger than Qyf~3~. Where known, grain size is indicated by a
subscripted letter or letters following unit symbols as follows: b,
boulder; g, gravel; a, arenaceous; s, silt, c, clay; e.g. Qyf~a~ is a
predominately sandy young alluvial fan deposit. Multiple letters are
used for more specific identification or for mixed units, e.g., Qyf~sa~
is a silty sand. In some cases, mixed units are indicated by a compound
symbol; e.g., Qyf~2sc~.

4\. Marine deposits are in part overlain by local, mostly alluvial fan,
deposits and are labeled Qopf. Letters designating grain size are
attached to the Qopf label.

5\. The Ma following U/Pb ages have attached subscripts; Ma~id~ for
isotope dilution analyses, and Ma~ip~ for ion probe analyses.

6\. Where units have limited extent or specific occurrences of units are
geologically important, the 7.5' quadrangle(s) in which they are found
are given in the unit descriptions.

**DESCRIPTION OF MAP UNITS**

Qaf **Artificial fill (late Holocene)**---Deposits of fill resulting
from human construction, mining, or quarrying activities; includes
compacted engineered and noncompacted nonengineered fill. Most large
deposits are mapped, but in some areas, no deposits are shown

Qw **Wash deposits (late Holocene)**---Unconsolidated bouldery to sandy
alluvium of active and recently active washes. Includes:

Qw~3~ **Wash deposits, Unit 3 (late Holocene)---**Unconsolidated
bouldery to sandy alluvium of active and recently active washes. Young
part of Qw

Qf **Alluvial fan deposits (late Holocene)**---Active and recently
active alluvial fans. Consists of unconsolidated, bouldery, cobbley,
gravelly, sandy, or silty alluvial fan deposits, and headward channel
parts of alluvial fans. Trunk drainages and proximal parts of fans
contain a greater percentage of coarse-grained sediment than distal
parts. Includes:

Qf~1~ **Alluvial fan deposits, Unit 1 (late Holocene)---**Recently
active alluvial fans. Consists of unconsolidated, bouldery, cobbley,
gravelly, sandy, or silty alluvial fan deposits, and headward channel
parts of alluvial fans. Trunk drainages and proximal parts of fans
contain greater percentage of coarse-grained sediment than distal parts.
Old part of Qf

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

Qv **Alluvial valley deposits (late Holocene)**---Active and recently
active fluvial deposits along valley floors. Consists of unconsolidated
sandy, silty, or clay-bearing alluvium

Qsw **Slope wash deposits (late Holocene)**---Unconsolidated sand,
cobbles, and pebbles deposited by water not confined to channels. Some
deposits are angular, multi-mineralogic sand derived from in-place
weathering of granitic rocks, but many include larger clasts transported
by torrential storms or clasts spalled from up-slope outcrops of bedrock

Qc **Colluvial deposits (late Holocene)**---Active and recently active
sand and silt colluvial deposits on hillsides and at the base of slopes;
in some places includes rubble and coarse debris not normally deposited
by colluvial processes. Unconsolidated

Qls **Landslide deposits (late Holocene)**---Highly fragmented to
largely coherent active landslides. Unconsolidated to consolidated. Most
mapped landslides contain scarp area as well as slide deposit. Many
originated in Pleistocene and all or part was reactivated during
Holocene

Qe **Eolian deposits (late Holocene)**---Unconsolidated, active or
recently active sand dune deposits, along coast (Newport Beach 7.5'
quadrangle)

Qm **Marine deposits (late Holocene)**---Unconsolidated, active or
recently active sandy beach deposits along coast

Qes **Estuarine deposits (late Holocene)**---Unconsolidated, active,
sandy, silty, and clayey organic-rich estuarine deposits (Newport Beach
7.5' quadrangle)

Ql **Lacustrine deposits (late Holocene)**---Dominantly gray, clayey,
silty, and fine-grained sandy lacustrine deposits. Underlies the floor
of the closed pull-apart depression in the Elsinore Fault Zone partly
filled by Lake Elsinore (Alberhill and Elsinore 7.5' quadrangles)

Qlv **Lacustrine and fluvial deposits** **(late Holocene)**---Dominantly
gray, clayey, silty, and fine-grained sandy lacustrine deposits
interbedded with fluvial deposits. Underlies the floor of the closed
pull-apart depression in the San Jacinto Fault Zone partly filled by
ephemeral Mystic Lake (Lakeview and El Casco 7.5' quadrangles)

Qyw **Young wash deposits (Holocene and latest
Pleistocene)**---Unconsolidated bouldery to sandy alluvium of active and
recently active washes

Qyf **Young alluvial fan deposits (Holocene and latest
Pleistocene)**---Unconsolidated deposits of alluvial fans and headward
drainages of fans. Consists predominately of gravel, sand, and silt.
Trunk drainages and proximal parts of fans contain higher percentage of
coarse-grained sediment than distal parts. Includes:

Qyf~7~ **Young alluvial fan deposits, Unit 7 (late Holocene and latest
Pleistocene)**---Unconsolidated alluvial fan deposits. Consists of
gravel, sand, and silt; youngest part of Qyf. In part distinguished on
basis of relative terrace levels

Qyf~6~ **Young alluvial fan deposits, Unit 6 (late Holocene and latest
Pleistocene)**---Unconsolidated alluvial fan deposits. Consists of
gravel, sand, and silt; young part of Qyf. In part distinguished on
basis of relative terrace levels

Qyf~5~ **Young alluvial fan deposits, Unit 5 (late Holocene and latest
Pleistocene)**---Unconsolidated alluvial fan deposits. Consists of
gravel, sand, and silt; intermediate to young part of Qyf. In part
distinguished on basis of relative terrace levels

Qyf~4~ **Young alluvial fan deposits, Unit 4 (late Holocene and latest
Pleistocene)**---Unconsolidated alluvial fan deposits. Consists of
gravel, sand, and silt; youngest part of Qyf. In part distinguished on
basis of relative terrace levels

Qyf~3~ **Young alluvial fan deposits, Unit 3 (late and middle
Holocene)**---Unconsolidated alluvial fan deposits. Consists of gravel,
sand, and silt; young part of Qyf. In part distinguished on basis of
relative terrace levels

Qyf~2~ **Young alluvial fan deposits, Unit 2 (early
Holocene)**---Unconsolidated alluvial fan deposits. Consists of gravel,
sand, and silt; intermediate part of Qyf. In part distinguished on basis
of relative terrace levels

Qyf~1~ **Young alluvial fan deposits, Unit 1 (early Holocene and late
Pleistocene)**---Unconsolidated alluvial fan deposits. Consists of
gravel, sand, and silt; old part of Qyf. In part distinguished on basis
of relative terrace levels

Qya **Young axial channel deposits (Holocene and latest
Pleistocene)**---Fluvial deposits along canyon floors. Consists of
unconsolidated sand, silt, and clay-bearing alluvium. Includes:

Qya~6~ **Young axial channel deposits, Unit 6**---Fluvial deposits along
canyon floors. Consists of unconsolidated sand, silt, and clay-bearing
alluvium. Intermediate to young part of Qya. In part distinguished on
basis of relative terrace levels

Qya~5~ **Young axial channel deposits, Unit 5**---Fluvial deposits along
canyon floors. Consists of unconsolidated sand, silt, and clay-bearing
alluvium. Intermediate to young part of Qya. In part distinguished on
basis of relative terrace levels

Qya~4~ **Young axial channel deposits, Unit 4**---Fluvial deposits along
canyon floors. Consists of unconsolidated sand, silt, and clay-bearing
alluvium. Intermediate part of Qya. In part distinguished on basis of
relative terrace levels

Qya~3~ **Young axial channel deposits, Unit 3**---Fluvial deposits along
canyon floors. Consists of unconsolidated sand, silt, and clay-bearing
alluvium. Intermediate part of Qya. In part distinguished on basis of
relative terrace levels

Qyv **Young alluvial valley deposits (Holocene and late
Pleistocene)**---Fluvial deposits along valley floors. Consists of
unconsolidated sand, silt, and clay-bearing alluvium. Includes:

Qyv~1~ **Young alluvial valley deposits, Unit 1 (early Holocene and late
Pleistocene)**---Fluvial deposits along valley floors west of Casa Loma
Fault. Consists of unconsolidated sand, silt, and clay-bearing alluvium

Qyc **Young colluvial deposits (Holocene and late Pleistocene)**---Sand
and silt colluvial deposits on hillsides and at the base of slopes;
inactive. In some places, may include rubble and coarse debris not
normally deposited by colluvial processes

Qyls **Young landslide deposits (Holocene and latest
Pleistocene)**---Highly fragmented to largely coherent landslide
deposits. Unconsolidated to consolidated. Most mapped landslides contain
scarp area as well as slide deposit. Many landslides in part reactivated
during late Holocene

Qye **Young eolian deposits (Holocene and latest Pleistocene)**---Sand
dune deposits, unconsolidated, inactive (Corona North 7.5' quadrangle)

Qypt **Young peat deposits (Holocene)**---Deposits of low density peat
and peaty sediments, (Newport Beach 7.5' quadrangle)

Qow **Old alluvial wash deposits (late to middle
Pleistocene)**---Unconsolidated to moderately indurated, gravel and sand
alluvial wash deposits

Qof **Old alluvial fan deposits (late to middle Pleistocene)**---Reddish
brown, gravel and sand alluvial fan deposits; indurated, commonly
slightly dissected. In places includes thin alluvial fan deposits of
Holocene age. Includes:

Qofv **Old alluvial fan deposits and young alluvial valley deposits
(Holocene and late to middle Pleistocene)**---Reddish-brown, gravel and
sand alluvial fan deposits; moderately indurated. Includes discontinuous
younger alluvial valley deposits locally

Qof~3~ **Old alluvial fan deposits, Unit 3 (late to middle
Pleistocene)**---Reddish brown, gravel and sand alluvial fan deposits;
indurated, commonly slightly dissected. Young part of Qof. In places
includes thin alluvial fan deposits of Holocene age

Qof~1~ **Old alluvial fan deposits, Unit 1 (late to middle
Pleistocene)**---Reddish brown, gravel and sand alluvial fan deposits;
indurated, commonly slightly dissected. Old part of Qof. In places
includes thin alluvial fan deposits of Holocene age

Qoa **Old axial channel deposits (late to middle
Pleistocene)**---Fluvial sediments deposited on canyon floors. Consists
of moderately indurated, commonly slightly dissected gravel, sand, silt,
and clay-bearing alluvium. Locally capped by thin, discontinuous
alluvial deposits of Holocene age. Includes:

Qoa~7~ **Old axial channel deposits, Unit 7 (late
Pleistocene)**---Fluvial sediments deposited on canyon floors. Consists
of moderately indurated, slightly dissected gravel, sand, silt, and
clay-bearing alluvium. Youngest subdivision of Qoa. Correlates with
Qoa~7~ unit in the Oceanside 30'x60' quadrangle to the south of the
Santa Ana 30'x60 quadrangle

Qoa~3~ **Old axial channel deposits, Unit 3 (middle
Pleistocene)**---Fluvial sediments deposited on canyon floors. Consists
of moderately indurated, slightly dissected gravel, sand, silt, and
clay-bearing alluvium. Intermediate part of Qoa. Correlates with Qoa~3~
unit in the San Bernardino 30'x60' quadrangle to the north of the Santa
Ana 30'x60 quadrangle

Qoa~1~ **Old axial channel deposits, Unit 1 (middle
Pleistocene)**---Fluvial sediments deposited on canyon floors. Consists
of moderately indurated, slightly dissected gravel, sand, silt, and
clay-bearing alluvium. Differs from Qoa in degree of dissection and in
places by relative terrace levels. Some deposits include thin alluvial
deposits of Holocene age. Older part of Qoa

Qov **Old alluvial valley deposits (late to middle
Pleistocene)**---Fluvial deposits along valley floors. Consists of
moderately indurated, commonly slightly dissected sand, silt, and
clay-bearing alluvium. Some deposits include thin alluvial deposits of
Holocene age

Qoc **Old colluvial deposits (late to middle Pleistocene)**---Colluvial
deposits on hillsides and at the base of slopes. Ranges from rubble to
sand. Unconsolidated to slightly indurated

Qols **Old landslide deposits (late to middle Pleistocene)**---Mostly
fragmented rock debris. Landslide morphology moderately to greatly
modified

Qop **Old paralic deposits, undivided (late to middle
Pleistocene)**---Paralic deposits consisting of poorly sorted,
moderately permeable, reddish-brown, interfingered strandline, beach,
estuarine and colluvial deposits composed of silt, sand and cobbles. The
paralic deposits extend from the Newport area south to the quadrangle
boundary. These deposits rest on the now emergent wave cut abrasion
platforms preserved by regional uplift. Where more than one number is
shown (e.g. Qop~2-4~) those deposits are undivided. Qop~5~ is not known
to occur in the Santa Ana quadrangle. Includes:

Qop~7~ **Old paralic deposits, Unit 7**---Paralic deposits consisting of
poorly sorted, moderately permeable, reddish-brown, interfingered
strandline, beach, estuarine and colluvial deposits composed of silt,
sand and cobbles. These deposits rest on the 9-11 m Bird Rock terrace.
Age about 80,000 years

Qop~6~ **Old paralic deposits, Unit 6**---Paralic deposits consisting of
poorly sorted, moderately permeable, reddish-brown, interfingered
strandline, beach, estuarine and colluvial deposits composed of silt,
sand and cobbles. These deposits rest on the 22-23 m Nestor terrace. Age
about 120,000 years

Qop~4~ **Old paralic deposits, Unit 4**---Paralic deposits consisting of
poorly sorted, moderately permeable, reddish-brown, interfingered
strandline, beach, estuarine and colluvial deposits composed of silt,
sand and cobbles. These deposits rest on the 34-37 m Stuart Mesa
terrace. Age about 200,000-300,000 years

Qop~3~ **Old paralic deposits, Unit 3**---Paralic deposits consisting of
poorly sorted, moderately permeable, reddish-brown, interfingered
strandline, beach, estuarine and colluvial deposits composed of silt,
sand and cobbles. These deposits rest on the 45-46 m Guy Fleming
terrace. 320,000-340,000 years

Qop~2~ **Old paralic deposits, Unit 2**---Paralic deposits consisting of
poorly sorted, moderately permeable, reddish-brown, interfingered
strandline, beach, estuarine and colluvial deposits composed of silt,
sand and cobbles. These deposits rest on the 55 m Parry Grove terrace.
Age about 413,000 years

Qop~1~ **Old paralic deposits, Unit 1**---Paralic deposits consisting of
poorly sorted, moderately permeable, reddish-brown, interfingered
strandline, beach, estuarine and colluvial deposits composed of silt,
sand and cobbles. These deposits rest on the 61-63 m Golf Course
terrace. Age about 450,000 years

Qop~2-6~ **Old paralic deposits, Units 2-6, undivided**---Paralic
deposits consisting of poorly sorted, moderately permeable,
reddish-brown, interfingered strandline, beach, estuarine and colluvial
deposits composed of silt, sand and cobbles. These deposits rest on the
22-55m terraces

Qop~3-6~ **Old paralic deposits, Units 3-6, undivided**---Paralic
deposits consisting of poorly sorted, moderately permeable,
reddish-brown, interfingered strandline, beach, estuarine and colluvial
deposits composed of silt, sand and cobbles. These deposits rest on the
22-46 m terraces

Qopf **Old paralic deposits (late to middle Pleistocene) overlain by
alluvial fan deposits---**Areas where old paralic deposits are capped by
extensive but thin, discontinuous, younger, locally derived, sandy
alluvial fan deposits

Qos **Old surficial deposits, undivided (Holocene and late
Pleistocene)**---Reddish-brown alluvial deposits not assigned to any
specific surficial materials unit of this age. Chiefly sand- to
boulder-sized clasts that are moderately consolidated and slightly to
moderately dissected. May include alluvial-fan, colluvial, or
valley-filling deposits

Qvof **Very old alluvial fan deposits (middle to early
Pleistocene)**---Mostly well-dissected, well-indurated, reddish-brown
alluvial fan deposits. Grain size chiefly sand and gravel. Includes:

Qvof~3~ **Very old alluvial fan deposits, Unit 3 (early
Pleistocene)**---Moderately well-dissected, well-indurated,
reddish-brown alluvial-fan deposits. Grain size chiefly sand and gravel.
Represents young part of Qvof

Qvof~1~ **Very old alluvial fan deposits, Unit 1 (early
Pleistocene)**---Mostly well-dissected, well indurated, reddish-brown
alluvial fan deposits. Grain size chiefly sand and gravel. Represents
old part of Qvof

Qvoa **Very old axial channel deposits (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. In places, includes thin,
discontinuous alluvial deposits of Holocene age. Deposits on
Gavilan-Lakeview surface in Lakeview Mountains are moderately
well-indurated light gray gravelly sand and contain abundant biotite.
Deposits in Quail Valley and Railroad Canyon area contain rounded
cobbles. Includes:

Qvoa~5~ **Very old axial channel deposits, Unit 5 (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. Younger part of Qvoa

Qvoa~4~ **Very old axial channel deposits, Unit 4 (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. Younger part of Qvoa

Qvoa~3~ **Very old axial channel deposits, Unit 3 (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. Intermediate part of Qvoa

Qvoa~2~ **Very old axial channel deposits, Unit 2 (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. In places, includes thin,
discontinuous alluvial deposits of Holocene age. Represents intermediate
age part of Qvoa

Qvoa~1~ **Very old axial channel deposits, Unit 1 (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. In places, includes thin,
discontinuous alluvial deposits of Holocene age. Represents old part of
Qvoa

Qvov **Very old alluvial valley deposits (late to middle
Pleistocene)**---Fluvial deposits flanking valley floors or perched
erosional remnants. Consists of well-indurated, moderately dissected
sand, silt, and clay-bearing alluvium. Some deposits may include thin
alluvial deposits of Holocene age

Qvols **Very old landslide deposits (middle to early
Pleistocene)**---Chiefly coherent landslide debris having highly
modified landslide morphology. Inactive and unlikely to reactivate under
current climatic and seismic conditions

Qvop **Very old paralic deposits, undivided (middle to early
Pleistocene)**---Paralic deposits consisting of Mostly poorly sorted,
moderately permeable, reddish-brown, interfingered strandline, beach,
estuarine and colluvial deposits composed of silt, sand and cobbles.
These deposits rest on the now emergent wave cut abrasion platforms
preserved by regional uplift

Qvor **Very old regolith (Pleistocene)**---Developed on both *in situ*
and transported material. Deeply weathered rock and soil regolith in the
San Timoteo Badlands (El Casco 7.5' quadrangle). Reddish-brown, highly
dissected

**Pauba Formation (Pleistocene)**---Siltstone, sandstone, and
conglomerate (Murrieta, Wildomar, and Bachelor Mountain 7.5'
quadrangle). Named by Mann (1955) for exposures in Rancho Pauba area
about 3.2 km southeast of Temecula. Vertebrate fauna from Pauba
Formation are of late Irvingtonian and early Rancholabrean ages
(Reynolds and Reynolds, 1990a; 1990b). Includes two informal members:

Qps **Sandstone member**---Brown, moderately well-indurated,
cross-bedded sandstone containing sparse cobble- to boulder-conglomerate
beds

Qpf **Fanglomerate member**---Grayish-brown, well-indurated, poorly
sorted fanglomerate and mudstone

Qlh **La Habra Formation (Pleistocene)**---Nonmarine mudstone, fluvial
sandstone, and conglomerate. First described by Eckis (1934) for
deposits in the La Habra area. Durham and Yerkes (1959) formalized name.
Occurs in the La Habra and Yorba Linda 7.5' quadrangles. Upper
two-thirds of formation is chiefly friable, gray to brown, sandy to
pebbly mudstone. Lower part of formation is gray to brown, massive to
crudely bedded, coarse-grained to pebbly sandstone. Unit has basal
conglomerate consisting of yellowish-tan to brownish-gray massive or
very crudely bedded, pebbly sandstone and conglomerate, which fills
channels cut in underlying strata. Conglomerate has about 15 degree
discordance with underlying beds. Locally contains clasts of white
siltstone derived from Puente Formation Mudstone in upper part locally
contains thin marly beds, which have freshwater snails, ostracods, and
plant remains. Formation ranges from 60 to 300 m thick

**Sandstone and conglomerate of Wildomar area (Pleistocene and
Pliocene)**---Unnamed sandstone and conglomerate unit unconformably
overlain by the Pauba Formation (Kennedy, 1977) (Murrieta and Wildomar
7.5' quadrangles). Lower part yields vertebrate fauna of late Blancan
age, 2 to 3 Ma; upper part yields fauna of Irvingtonian-age, less than
0.85 Ma (Reynolds and Reynolds, 1990a, 1990b; Reynolds and others,
1990). At Chaney Hill in Murrieta area, unit contains 0.7 Ma Bishop ash
(Merriam and Bishoff, 1975). Estimated maximum thickness is 75 m.
Includes informal subdivisions:

QTws **Sandstone unit**---Primarily friable, pale yellowish-green,
medium-grained, caliche-rich sandstone

QTwc **Conglomerate unit**---Primarily cobble-and-boulder conglomerate.
Conglomerate clasts are locally derived

Qch **Coyote Hills Formation (Pleistocene)**---Chiefly nonmarine
mudstone and pebbly sandstone (La Habra 7.5' quadrangle), containing
some intertidal (?) deposits in western part. Mudstone is grayish,
massive, and friable; sandstone is medium to coarse grained or pebbly,
and thickly bedded. First described and named by Yerkes (1972) for
deposits in Coyote Hills south of Puente Hills. At its type locality
unit is about 220 m thick; upper 150 m is 60 percent mudstone and 40
percent sandstone, lower 65 m is pebbly sandstone (Yerkes, 1972). Coyote
Hills Formation unconformably rests on San Pedro Formation

Qsp **San Pedro Formation** **(Pleistocene)**---Shallow marine sandstone
and pebbly sandstone (La Habra quadrangle). Upper part consists of white
to brown, friable, massive sandstone, which contains abundant marine
mollusks, and locally includes conglomerate beds. In places, pebbly
sandstone forming base of upper part is locally well indurated. Lower
part consists of brown to gray, massive, silty sandstone which contains
scattered marine mollusks. First described as San Pedro sand by Dall in
1898; named for exposures at Harbor Hill, near head of San Pedro Harbor.
Formalized as San Pedro Formation by Kew (1923). Maximum exposed
thickness in Puente Hills area is 100 m; thickness in subsurface is
about 535 m (Yerkes, 1972). Divided in the southern La Habra 7.5'
quadrangle into four mappable units. In succession is a lower sequence
of siltstone and claystone (Qsp~1~), overlain by sandstone (Qsp~2~),
that in turn is overlain by siltstone and claystone (Qsp~3~), and an
upper unit of sandstone (Qsp~4~)

**San Timoteo beds of Frick (1921) (Pleistocene and
Pliocene)**---Lithologically diverse sandstone, conglomeratic sandstone,
and conglomerate (El Casco and Sunnymead 7.5' quadrangles). Nearly all
sandstone is arkosic and much is lithic. Named by Frick (1921) for upper
Pliocene, vertebrate-bearing, nonmarine strata in San Timoteo Canyon.
Upper part of San Timoteo beds contain vertebrate fauna of earliest
Pleistocene Irvingtonian I age (Repenning, 1987); Eckis had earlier
suggested a Pleistocene age for upper part of section in 1934. Albright
(1997) shows vertebrate fossils are throughout most of upper part of
unit. Lower part of San Timoteo beds of Frick (1921) is Pliocene. Clasts
within unit appear to be entirely derived from Transverse Range sources
similar in composition to rocks presently exposed in eastern San Gabriel
Mountains, central San Bernardino Mountains, and in San
Bernardino-Yucaipa area (Matti and Morton, 1993). In past, contact
between San Timoteo beds of Frick (1921) and underlying Mount Eden
Formation inconsistently placed at various stratigraphic positions. In
this report, contact is placed at boundary between older
fluvial-lacustrine deposits (Mount Eden Formation) and younger
fluvial-alluvial fan deposits (San Timoteo beds of Frick (1921)). Age of
this boundary is about 4.3 Ma (B. Albright, per. commun., 1998).
Includes three informal members, and five subdivisions of members:

Qstu **Upper member (Pleistocene)**---Gray coarse-grained, moderately
indurated sandstone and conglomerate. Contains early Pleistocene
Irvingtonian I, Shutt Ranch and El Casco local faunas, about 1.8 Ma
(Repenning, 1987). Erodes to form sharp-ridged badlands topography.
Locally subdivided into:

Qsts **Conglomeratic sandstone beds**---Conglomeratic sandstone that
appears to be derived from adjacent sedimentary beds. Forms small
lens-shaped body along crest of anticline in the western part of the San
Timoteo Badlands

Qstcq **Quartzite-bearing conglomerate beds**---Distinctive,
well-indurated, conglomerate consisting largely of clasts derived from
central part of San Bernardino Mountains. Characterized by quartzite
clasts derived from Precambrian terrain and by megaporphyry clasts
(Matti, and Morton, 1993; Morton and others, 1986). Beds found in upper
part of upper member. Contains early Pleistocene Irvingtonian I, Olive
Dell local fauna (Repenning, 1987), about 1.3 Ma

Tstm **Middle member (Pliocene)**---Dominate lithology is light-gray,
pebbly to cobbley, moderately to well-indurated, medium- to
coarse-grained sandstone containing conglomerate beds up to 9 m in
thickness. Pale brown- to light-gray fined-grained sandstone to pebbly
sandstone is subordinate. Overall, member consists of about 70 percent
sandstone and 30 percent conglomerate; conglomerate more abundant in
upper part. Includes common reddish-brown stratigraphic intervals
consisting of oxidized sandstone, which are not paleosols, and
reddish-brown clay-rich intervals, which may be paleosols. Erodes to
form sharp-ridged badlands topography. Forms hogbacks on north side of
San Timoteo Canyon. Included within Tstm is highly deformed sandstone,
pebbly sandstone, and conglomerate (Tstd) located along western part of
badlands adjacent to San Jacinto fault zone. Its stratigraphic position
within Tstm is not resolved

Tstl **Lower member (Pliocene)**---Mostly gray, moderately well
indurated, well-sorted fine-grained sandstone containing subordinate
pebble lenses, and sparse medium-grained sandstone beds. Represents
distal flood plain deposit. Erodes to form slightly more rounded
badlands topography than younger part of San Timoteo beds. Included
within and at the base of Tstl is an interval of buff to reddish-brown
fine- to thick-bedded coarse-grained arkosic sandstone (Tstl~1~). Above
the basal Tstl~1~ is a section of mostly greenish-gray claystone and
siltstone with thick and crudely bedded coarse-grained sandstone
characterized by ripple lamination (Tstl~2~)

QTs **Unnamed late Cenozoic sedimentary rocks in Riverside and Corona
areas (early Pleistocene to late Pliocene?)**---Lithologically diverse,
moderately indurated, gray to brown, coarse-grained sandstone, pebbly
sandstone, and conglomerate. In the Riverside West 7.5' quadrangle, most
clasts in unit were derived from San Bernardino Mountains. In Riverside
area, unit appears to be derived from units found in Santa Ana River
drainage. Southeast of Riverside (Riverside East 7.5' quadrangle),
clasts are locally derived from Peninsular Ranges sources

QTt **Late Cenozoic** c**onglomerate of Temescal area (early Pleistocene
to late Pliocene?)**---Cobble conglomerate deposited on deeply weathered
surface of Paleocene(?) age (Corona South 7.5' quadrangle). Clasts
appear to be locally derived

QTc **Conglomeratic sedimentary rocks of Riverside West 7.5' quadrangle
(early Pleistocene to late Pliocene?)**---Boulder conglomerate
containing locally derived granitic and metamorphic clasts. Underlain by
cobble conglomerate containing clasts derived from San Bernardino basin
and San Bernardino Mountains area. Locally derived boulder conglomerate
is brownish gray. The underlying cobble conglomerate is gray and
contains rusty and black-stained clasts locally. Cobble conglomerate
appears to be derived from units in Santa Ana River drainage

QTn **Late Cenozoic sedimentary rocks of Norco area (early Pleistocene
to late Pliocene?)**---In Norco area (Corona North 7.5' quadrangle) unit
includes locally derived clasts as well as clasts derived from the San
Bernardino Mountains

Tta **Temecula Arkose (Pliocene)**---Mainly pale greenish-yellow,
medium- to coarse-grained, indurated sandstone (Bachelor Mountain 7.5'
quadrangle). Includes thin discontinuous beds of tuffaceous sandstone,
siltstone, and claystone, and some pebble and conglomerate beds having
locally derived clasts. Named by Mann (1955) for exposures of nonmarine
fluvial sandstone exposed southeast of Temecula. Kennedy (1977) assigned
unit late Pliocene Blancan IV-V mammal age (2.2 to 2.8 My) based on
vertebrate assemblages collected east of quadrangle. Assemblages include
*Nannippus, Hypolagus, Tetrameryx, Equus,* and *Odocoileus* (Golz, and
others, 1977). Later work establishes first occurrence of *Tetrameryx*
as Irvingtonian I rather than late Blancan (Woodburne, 1987), placing
Temecula Arkose age nearer 1.9 Ma (late Pliocene) than 2.2 Ma. A
microtine fauna from unit in Radec area, about five miles east of Santa
Ana quadrangle, is considered to have age of 4.6 Ma (Blancan I)
(Repenning, 1987). Thickness of the Temecula Arkose ranges from 90 to
over 550 m (Kennedy, 1977)

Tf **Fernando Formation (Pliocene)**---Siltstone, sandstone, pebbly
sandstone, and conglomerate; widespread in the northwestern Santa Ana
Mountains and southern Puente Hills. Name introduced by Eldridge and
Arnold (1907) for marine deposits on northwest side of San Fernando
Valley. Formalized by Kew (1924) for similar-appearing rocks in Ventura
basin. Durham and Yerkes (1964) defined current usage in Santa Ana
quadrangle. In Puente Hills, Fernando Formation is about 1825 m thick
(Yerkes, 1972). Lower part equivalent to Repetto Formation (Woodring,
1938). Includes two members separated by regional erosional
unconformity:

Tfu **Upper Member**---In eastern part of Puente Hills consists of
sandstone, pebbly sandstone, and sandy conglomerate. In western part of
Puente Hills, upper member consists of three units. From youngest to
oldest, (1) 250 m of pale gray, thick-bedded to massive, friable, fine-
to medium-grained sandstone and brownish-gray, massive, pebbly
sandstone; (2) 590 m of pale gray, massive, poorly sorted, friable,
micaceous rock ranging from siltstone to medium-grained sandstone; (3)
200 of sandstone, pebbly sandstone, and pebbly conglomerate (Yerkes,
1972). Sandstone is generally massive, pale gray to brownish gray,
silty, fine to coarse grained, poorly sorted, and friable. Pebbly
sandstone is brownish gray thick bedded to massive, poorly sorted, and
friable. The conglomerate is brownish and consists of clasts up to 45 cm
in length. Abundant marine mollusks occur in upper part of member.
Included in Tfu is zone of predominantly conglomeratic rock (Tfuc),
which is about 490 m thick in western part of Puente Hills

Tfl **Lower Member**---Siltstone, sandstone and conglomerate in
northwestern part of Puente Hills. Includes brownish-gray to pale-gray,
sandy, micaceous siltstone, fine- to medium-grained friable sandstone,
and brownish-gray, unsorted, massive, pebbly conglomerate. Contains
local beds of intraformational breccia, and locally common foraminifera.
Conglomerate at base of member contains angular clasts of white
Miocene-age siltstone and near-black diabase. Member is up to 730 m
thick. Included in Tfl is zone of predominantly conglomeratic rock
(Tflc) of unknown thickness and unknown extent

Tn **Niguel Formation (Pliocene)**---Marine interbedded sandstone,
conglomeratic sandstone, and conglomerate. Named by Vedder (1957) for
exposures in San Juan Capistrano 7.5' quadrangle. Sandstone is brownish
gray, coarse grained, and poorly sorted. Brownish-gray conglomerate,
consists of unsorted clasts 2.5 to 25 cm in diameter, and contains
blocks of locally derived siltstone. Marine mollusks suggest deposition
in sublittoral-depth water (Vedder, 1960)

Tns **Sandstone of Norco area (Pliocene)**---Poorly exposed, unnamed,
marine sandstone near city of Norco (Corona North 7.5' quadrangle).
Unconsolidated, greenish-yellow sandstone and sparse conglomerate
lenses. Locally contains abundant, poorly preserved shallow marine
fossils including *Anadara* cf. *A. trilineata* (Conrad)*, Chione* sp.,
*Lucinoma* cf. *L. annulata* (Reeve)*,* and *Diodora* sp. (J.D. Mount,
per. commun., 1973). Unit may represent shallow-water eastward extension
of Fernando Formation. Sparse conglomerate lenses include clasts of
exotic silicic volcanic rocks. In places, nonconformably buttressed
against granitic rock. Ash at base of formation deposited on granite in
what are interpreted to have been tide pools, is ash of Taylor Canyon
(per. commun., A.M. Sarna-Wojcicki, 1990) having age of 2.6 Ma

Tc **Capistrano Formation (early Pliocene and Miocene)**---Marine
sandstone and siltstone; widespread unit in the San Joaquin Hills area.
Named by Woodford (1925) for exposures of marine strata near city of San
Juan Capistrano. Includes one member and one separately mapped facies:

Tco **Oso Member**---White to light gray, massive, medium- to
coarse-grained, friable sandstone. Contains scattered matrix-supported
pebbles and cobbles. Named by Vedder and others (1957) for marine
sandstone in coastal Orange County. Upper part contains foraminifera of
Kleinpell's upper Mohnian or Delmontian Stage (Vedder and others, 1957),
and in area of San Juan Capistrano to Dana Point, late Miocene and early
Pliocene foraminifera, shark teeth, echinoids, and whalebones (White,
1956, 1971; Ingle, 1971, 1972; Vedder, 1972)

Tcs **Siltstone facies**---White to pale gray, massive to crudely
bedded, friable, siltstone and mudstone. Informally designated by Morton
and Miller (1981) for exposures in southern Orange County. Contains
sandstone and calcareous mudstone beds, and sparse diatomaceous and
tuffaceous beds. Up to 730 m thick

Tme **Mount Eden Formation of Fraser (1931) (early Pliocene and
Miocene)**---Sandstone, mudrock, conglomeratic sandstone, and
sedimentary breccia (Lakeview and El Casco 7.5' quadrangles). First
described as Eden beds by Frick (1921), but name was preempted. Fraser
(1931) informally designated same unit the Mount Eden Formation. Named
for exposures in the vicinity of Mount Eden (El Casco 7.5' quadrangle).
Albright (1997), Frick (1921), May and Repenning (1982), and Repenning
(1987), described vertebrate fauna from Mount Eden Formation and Axelrod
(1937, 1950) described flora. Includes five informal members:

Tmeus **Upper sandstone member (early Pliocene and Miocene)**---Consists
principally of interbedded sandstone and mudrock. Dominant lithology is
moderately well indurated, ledge-forming, thin- to medium-bedded,
well-sorted pale-brown sandstone. Sandstone contains characteristic
climbing ripple laminations, convoluted bedding, and locally
cross-laminations. Interbedded with subordinate thin- to medium-bedded
intervals of fissile to hackly-fracturing mudrock. Unit has prominently
reddish-brown interval in the Lamb Canyon area

Tmem **Mudrock member (early Pliocene and Miocene)**---Hackly fracturing
to locally fissile, dark gray-green mudrock. Weathers to form smooth
rounded slopes

Tmels **Lower sandstone member (Miocene)**---Green, olive green, and
gray sandstone, pebbly sandstone, and minor limestone; locally contains
abundant limey concretions. Mudrock subordinate in this member.
Southeastward, unit is progressively better indurated, and in
southeastern exposures is ledge-forming sandstone and pebbly sandstone.
Well indurated rock north of Mount Eden contains middle Miocene, late
Hemphillian Mount Eden local fauna; about 5.3 Ma (Repenning, 1987) or
5.6 Ma (Albright, 1997)

Tmea **Arkosic sandstone member (Miocene)**---Mostly thick-bedded,
indistinctly bedded, moderately to well-indurated, buff, gray,
greenish-gray, and reddish-brown, coarse-grained arkosic sandstone,
pebbly sandstone, and conglomerate. Contains some interbeds of
fine-grained sandstone, siltstone, and rare shale. Includes sparse limey
concretions, which are not as common as in the overlying Lower sandstone
member. Unit is possibly coeval or in part coeval with conglomeratic
sandstone. Contains tongues of monolithologic boulder breccia (Tmeb).
Giant clasts in breccia are up to 6 m in diameter. Apparently represents
debris flow deposits. Breccia tongues occur at several different
horizons mostly in Lamb Canyon and Laborde Canyon areas. Clasts are
entirely tonalite of Lamb Canyon, a massive sphene-bearing
biotite-hornblende tonalite, which crops out in northeastern part of El
Casco 7.5' quadrangle

Tmec **Conglomeratic sandstone member (Miocene)**---Reddish-brown,
massive to indistinctly bedded, coarse-grained sandstone, pebbly
sandstone, and conglomerate. Basal unit of Mount Eden Formation of
Frasier (1931). Lower part is dominated by conglomerate and upper part
by sandstone. Moderately well decomposed clasts are locally derived
Peninsular Ranges Province basement rocks

Tch **Sandstone and conglomerate in southeastern Chino Hills (early
Pliocene and Miocene)**---Poorly exposed marine and nonmarine
sedimentary sandstone and conglomerate in the Arena Blanca syncline area
of southeastern Chino Hills (Prado Dam 7.5' quadrangle). Stewart and
Stewart (1930) and Woodford and others (1944) reported Pliocene
foraminifera from these rocks. Similar appearing rocks southeast to
Wardlow Wash, Bedford Canyon, and Brown Canyon are included in this unit
(Gray, 1961). Smith (1960) described Pliocene foraminifera from these
rocks. A meager megafauna was collected on northwest side of Bedford
Canyon and included a fragment of *Cantharus* sp. of Pliocene age (Gray,
1961). In the Chino Hills this unit was differentiated from underlying
Puente Formation by Daviess and Woodford (1949) and by Gray (1961) but
was included within Puente Formation by Durham and Yerkes (1964).
Fossils obtained from sand-and-gravel quarry included marine
invertebrate and nonmarine vertebrate faunas and nonmarine flora (R.E.
Reynolds, per. commun., 1998). Vedder (per. commun. to T.H. McCulloh,
1997) identified a relatively large molluscan taxa from material
collected by Reynolds. Vedder considered best correlation of molluscan
taxa is to lower part of Fernando Formation and upper part of Capistrano
Formation. Foraminifera collected in 1996(?) were identified as
Delmontian age (T.H. McCulloh, per. commun., 1997). Indicates unit at
least in part coeval with Sycamore Canyon member of Puente Formation

Tp **Puente Formation (early Pliocene and Miocene)**---Marine sandstone,
siltstone, and shale underlying most of the Puente Hills and extending
into adjacent areas. Named by Eldrige and Arnold (1907) for exposures in
Puente Hills. English (1926) extended distribution of Puente Formation
to area south of Puente Hills, subdividing three units, from youngest to
oldest, (1) shale, sandstone, and conglomerate (2) sandstone, and (3)
shale. Daviess and Woodford (1949) subdivided Puente Formation in
northwestern Puente Hills into four members, from youngest to oldest,
(1) Sycamore Canyon member, (2) upper siltstone member, (3) sandstone
member, and (4) lower siltstone member. Schoellhamer and others (1954)
later designated formalized member names that are in current usage

Tpsc **Sycamore Canyon Member (early Pliocene and
Miocene)**---Predominantly sandstone and pebble conglomerate. Named by
Daviess and Woodford (1949) for exposures at Sycamore Canyon (San Dimas
7.5' quadrangle) just north of the Santa Ana quadrangle in the
northwestern Puente Hills. Sycamore Canyon Member is laterally variable,
composed of varying amounts of pale gray, thick-bedded to massive,
medium- to coarse-grained, friable sandstone; pale gray, thin-bedded,
siliceous siltstone; pale gray, poorly bedded siltstone, and
brownish-gray, massive conglomerate. Contains bathyal depth
foraminiferal fauna (Yerkes, 1972). Included in Tpsc is a zone of
predominantly conglomeratic rock (Tpscc) of unknown extent

Tpy **Yorba Member (Miocene)**---Siltstone and sandstone; siltstone
predominates. Named by Schoellhamer and others (1954) for Yorba bridge
east of the community of Atwood. White to gray, thin bedded, micaceous
and siliceous siltstone and sandy siltstone. Siltstone contains beds of
fine-grained sandstone and white to pale gray limy concretions and
concretionary beds. In eastern Puente Hills, upper part of Yorba
contains large boulders in relatively fine-grained rocks and is
interpreted as turbidity current deposit (Durham and Yerkes, 1959).
Included in Tpy is a zone of predominantly conglomeratic rock (Tpyc) of
unknown extent

Tpsq **Soquel Member** **(Miocene)**---Sandstone and siltstone;
sandstone predominates. Named by Schoellhamer and others (1954) for
exposures in Soquel Canyon in eastern Puente Hills. Gray to
yellowish-gray, massive to well-bedded, medium- to coarse-grained,
poorly sorted sandstone interbedded with matrix-supported pebbly
sandstone. Many sandstone beds are graded. Locally conglomeratic. Lower
part of section commonly contains ellipsoidal calcite-cemented
concretions 30 cm to 1.5 m in diameter

Tplv **La Vida Member (Miocene)**---Siltstone and subordinate sandstone.
Named by Schoellhamer and others (1954) for exposures near La Vida
Mineral Springs in eastern Puente Hills. Light-gray to black, massive to
well-bedded, generally friable siltstone. Weathered surfaces are
typically white or pale gray. Locally consists of porcellaneous
siltstone or shale. Contains widespread fish remains, abundant
foraminifera, local phosphate nodules, and sparse limy siltstone.
Interbedded sandstone beds range from 2 cm to over 1 m in thickness.
Includes a few beds of vitric tuff

Tlm **Lake Mathews Formation (Miocene)**---Poorly exposed sequence of
massive, greenish-gray mudstone and minor conglomerate, and poorly
bedded white to gray sandstone, pebbly sandstone, and conglomerate (Lake
Mathews 7.5' quadrangle). Name introduced by Proctor and Downs (1963)
and formalized by Woodford and others (1971). Contains vertebrate fauna
including *Ustattochoeerus* cf. *Californicus* (Merriam) (Proctor and
Downs, 1963) indicating a Claredonian age (Woodburne, 1987) for
formation

Tcgr **Rhyolite clast conglomerate of Lake Mathews area
(Miocene?)**---Massive, indurated, coarse-grained, sandstone-matrix,
cobble conglomerate (Lake Mathews and Steele Peak 7.5' quadrangles).
Matrix feldspars largely altered to clay. Cobbles include exotic red
rhyolite in addition to locally derived clasts. Occurs as three slightly
elevated channel deposit remnants on 640 m Gavilan-Lakeview erosional
surface of Woodford and others (1971)

Tcg **Conglomerate of Lake Mathews area (Miocene?)**---Massive,
indurated, coarse-grained, sandstone-matrix, cobble conglomerate (Lake
Mathews 7.5' quadrangle). Similar to rhyolite clast conglomerate of Lake
Mathews area, but lacks rhyolite clasts

Tm **Monterey Formation (Miocene)**---Siliceous and diatomaceous marine
siltstone and sandstone correlated with Monterey Formation (Blake, 1856;
Kew, 1923; Bramlette, 1946) of central California. Predominately
siltstone and sandstone. Interbedded white to pale brown, thinly
laminated siltstone and tan, fine- to medium-grained feldspathic
sandstone. Contains abundant foraminifera and fish remains; locally
contains diatom fragments. In the Capistrano area, lower part of Puente
Formation grades laterally southward into Monterey Formation (Vedder,
and others, 1957)

Tvsr **Santa Rosa basalt of Mann (1955) (Miocene)**---Remnants of basalt
flows having relatively unmodified flow surfaces (Murrieta, Wildomar,
and Sitton Peak 7.5' quadrangles). Hawkins (1970) provides detailed
petrologic description of basalt. Originally described by Fairbanks
(1892) and informally named by Mann (1955) for basalt flows in vicinity
of Rancho Santa Rosa, west of Temecula. Name also has been applied to
basalts in general area of Temecula and Santa Ana Mountains, but in this
report, is restricted to rocks in area west of Temecula. Southwestern
part of Santa Rosa basalt of Mann (1955) extruded on deeply weathered
surface of low relief similar to Paleocene age surfaces found elsewhere
in southern California. Also, western part of unit and where found in
vicinity of Elsinore Peak, was extruded on sedimentary rocks closely
resembling Paleogene-age rocks. Morton and Morton (1979) report
whole-rock conventional potassium-argon ages for Santa Rosa basalt of
6.7 and 7.4 Ma. Slightly older age of 8.7 Ma was obtained by Hawkins
(1970)

Tvt **Basalt of Temecula area (Miocene)**---Includes scattered exposures
of basalt north and east of Temecula, and a small exposure of vesicular
basalt within valley area of Elsinore Fault zone near Wildomar (Mann,
1955; Kennedy, 1977; Hull, 1990). East of Temecula there are a few
exposures of vesicular basalt and what appears to be a dissected cinder
cone and scattered volcanic bombs (Mann, 1955)

Tvh **Basalt of Hogbacks (Miocene)**---Basalt capping Hogbacks northeast
of Temecula (Murrieta 7.5' quadrangle). Remnant of channel-filling
basalt flow. Thin deposit of unconsolidated gray stream gravel underlies
axial part of channel-filling basalt. Basalt is less vesicular than most
of Santa Rosa basalt of Mann (1955) and tends to break into slabby
fragments. Whole-rock conventional potassium-argon ages are 10.4 and
10.8 Ma (Morton and Morton, 1979)

Tvep **Basalt of Elsinore Peak (Miocene)**---Black vesicular basalt
capping Elsinore Peak. Overlies a thin sequence of Paleogene(?)
sandstone. Whole rock conventional potassium-argon age of basalt is 11.6
Ma and ^40^Ar/^39^Ar age is 11.2 Ma (R. Fleck, per. commun., 1998).
Occurs in the Wildomar 7.5' quadrangle

Tsob **San Onofre Breccia (middle Miocene)**---Chiefly marine
sedimentary breccia, conglomerate, and lithic sandstone (Laguna Beach
and San Juan Capistrano 7.5' quadrangles). Named by Ellis and Lee (1919)
for exposures in San Onofre Hills, San Diego County. Detailed
descriptions of petrology and paleontology are given by Woodford (1925),
who described unit as "San Onofre facies of the Temblor Formation" based
on occurrence of *Turritella ocoyana* fauna in sandstone underlying
breccia. San Onofre Breccia consists of green, greenish-gray, gray,
brown, and white, massive to well bedded, mostly well-indurated breccia
with interbedded conglomerate, sandstone, siltstone, and mudstone.
Well-bedded fine-grained parts and poorly bedded to massive coarse parts
of unit are discontinuous, grading laterally into one another. Local
diatomaceous shale and tuff beds. Contains *Turritella* *ocoyana*.
Breccia consists of large angular clasts derived from basement rock
sources offshore to west. Unit is characterized by clasts of blueschist
and related rocks derived from Catalina Schist (Woodford, 1924). Unit is
up to 900 m thick

Tt **Topanga Formation (middle Miocene)**---Marine sandstone, siltstone,
and shale. Named by Kew (1923) for predominantly sandstone unit in Santa
Monica Mountains; further subdivided by Vedder (1957). Kew (1923)
recognized similar rocks in Puente Hills, Santa Ana Mountains, and San
Joaquin Hills. At type locality, Topanga Canyon, unit contains middle
Miocene fauna characterized by *Turritella ocoyana*. In Santa Ana
quadrangle formation includes three members, from youngest to oldest:

Ttp **Paulerino Member**---Pale gray, massive, tuffaceous sandstone and
thin-bedded siltstone. Contains some breccia interbeds and locally
andesite breccia. Named by Vedder (1957) for exposures in San Joaquin
Hills, coastal Orange County. Contains assemblage of middle Miocene
foraminifera

Ttlt **Los Trancos Member**---Pale gray to brownish-gray, thin- to
medium-bedded siltstone and fine-grained sandstone. Includes some
interbedded medium- to coarse-grained sandstone and shale beds. Named by
Vedder (1957) for exposures in San Joaquin Hills, coastal Orange County.
Foraminifera indicate middle Miocene age. Member is up to 945 m thick

Ttb **Bommer Member**---Gray to brownish-gray, thick-bedded, medium- to
coarse-grained sandstone and interbedded fine-grained sandstone and
siltstone. Locally conglomeratic. Named by Vedder (1957) for exposures
in San Joaquin Hills, coastal Orange County. Contains middle Miocene
megafossils

Tvem **El Modeno Volcanics (middle Miocene)**---Andesite, tuff,
tuff-breccia, and basalt. Named by Schoellhamer and others (1954) for
volcanic rocks exposed 5 km east of settlement of El Modeno on
northwestern side of Santa Ana Mountains (not to be confused with town
of El Modena). Yerkes (1957) gives detailed description of El Modeno
Volcanics. Includes:

Tvema **Andesitic volcanic rocks**---Extrusive volcanic rocks; primarily
of andesitic composition

Tvemt **Tuff and tuff breccia**---Clastic volcanic rocks; primarily tuff
and tuff breccia

Tvemb **Basalt**---Extrusive volcanic rocks; primarily of basaltic
composition

**Volcanic intrusive rocks associated with El Modeno Volcanics (middle
Miocene)**---Dikes, sills, and small irregular shaped bodies. Includes:

Ta **Andesitic intrusive rocks**---Porphyritic intrusive rock primarily
of andesitic composition; most are thoroughly altered and decomposed

Td **Diabase intrusive rocks**---Diabasic textured shallow intrusive
rocks, most are thoroughly altered and decomposed

Tvss **Vaqueros, Sespe, Santiago, and Silverado Formations,
undifferentiated (early Miocene, Oligocene, and Paleocene)**---Sandstone
and conglomerate

Tv **Vaqueros Formation (early Miocene, Oligocene, and late
Eocene)**---Predominantly sandstone. Originally described as Vaqueros
sandstone by Hamlin (1904) for marine deposits in Los Vaqueros Valley
along east slope of Santa Lucia Range in central California. Correlation
with southern California deposits is based upon *Turritella inezana*
fauna. In San Joaquin Hills, unit consists of brownish-gray, massive- to
thick-bedded sandstone and sandy siltstone, having interbeds of
siltstone and shale, mudstone, and minor conglomerate. Shale and
siltstone are thin bedded. Up to 1,160 m thick in quadrangle (Vedder,
1975). Contains early Miocene shallow-water marine megafossil assemblage

Ts **Sespe Formation (early Miocene, Oligocene, and late Eocene)**---In
San Joaquin Hills area, Sespe is varied colored from gray to red,
massive- to thick-bedded, nonmarine conglomeratic sandstone and clayey
and silty sandstone. Bedforms are poorly developed. Watts (1897)
originally described unit as Sespe brownstone formation. It was later
described by Eldridge and Arnold (1907) and redefined by Kew (1924) for
nonmarine conglomeratic deposits exposed in Sespe Creek in Ventura
County, where Sespe conformably underlies marine Vaqueros Formation.
Continental vertebrate fossil collections range in age from Eocene to
early Miocene (Bailey and Jahns, 1954; Woodburne 1987)

Tvs **Vaqueros and Sespe Formations, undifferentiated (early Miocene,
Oligocene, and late Eocene)**---Interbedded marine and nonmarine
sandstone and conglomerate assigned to the Sespe and Vaqueros
Formations. In the Puente Hills, Santa Ana Mountains, and San Joaquin
Hills, marine fossil-bearing strata of Vaqueros Formation are bed-by-bed
interlayered with nonmarine rocks of Sespe Formation to degree that
formations cannot be mapped as separate units. Mixed unit locally
includes boulder conglomerate (Woodford and others, 1973)

Tcga **Conglomerate of Arlington Mountain (Paleogene?)**---Cobble
conglomerate. Found in two small areas north of Arlington Mountain along
the boundary of the Lake Mathews and Riverside West 7.5' quadrangles.
Conglomerate is composed of exotic welded tuff clasts, some of which
contain piemontite, a characteristic mineral in welded tuff clasts in
conglomerates of Poway Group (Woodford and others, 1968). Minor clasts
of exotic quartzite also occur within unit. Welded tuff clasts appear
identical to those common in Sespe Formation and in conglomerate of
Eocene Poway Group found in quadrangle to south. Very localized
exposures of identical-appearing conglomerate occurs at crest of ridge
east of town of Elsinore in the eastern part of the Elsinore 7.5'
quadrangle. Reworked volcanic clasts are also found in some Pleistocene
alluvial deposits adjacent to conglomerate

Tep **Sandstone of Elsinore Peak (Paleogene?)**---Basalt capping
Elsinore Peak is underlain by a thin sequence of well indurated, white
to pale gray, coarse-grained, locally pebbly sandstone (Wildomar 7.5'
quadrangle). Some sandstone lacks basalt cover

Tsa **Santiago Formation (middle Eocene)**---Continental and marine
sandstone and conglomerate. In Santa Ana quadrangle first described by
Dickerson (1914) and correlated with Tejon Formation to north. Later
Woodring and Popenoe (1945) proposed name Santiago Formation for
exposures at Santiago Creek on west side of Santa Ana Mountains. They
considered Santiago Formation to be late Eocene. Later Schoellhamer and
others (1981) assigned it to middle Eocene. Lower part of formation
consists of conglomerate composed of clasts of quartzite, volcanic
rocks, granitic rocks, sandstone, and metaconglomerate, none of which
appear to be of local origin (Schoellhamer and others, 1981). Above
conglomerate is thick sequence of pale gray feldspathic sandstone and
lesser interbedded siltstone. Lower part of sandstone contains marine
mollusks; silicified wood is common in upper part of sandstone, which is
probably nonmarine

Tsi **Silverado Formation (Paleocene)**---Nonmarine and marine
sandstone, siltstone, and conglomerate. Dickerson (1914) first
recognized Paleocene rocks in Santa Ana Mountains, and based on faunal
similarities, correlated strata with Martinez Formation of central
California. Woodring and Popenoe (1945) described unit in detail and
named it Silverado Formation. Formation was deposited on deeply
weathered erosional surface. Rocks underlying Silverado are
characteristically saprolitic. Silverado Formation consists of basal
conglomerate overlain by relatively thin sequence of sandstone and
siltstone. Distinctive Claymont clay bed overlies sandstone and
siltstone sequence, and is overlain by thick sequence of sandstone,
siltstone, and conglomerate that includes second clay bed, the Serrano
clay bed. Basal conglomerate is thoroughly weathered, 2 to 25 m thick,
massive, pale gray to reddish-brown, pebble conglomerate. Very locally
is boulder conglomerate. Overlying conglomerate is sandstone and
siltstone which is also thoroughly weathered, consisting largely of
quartz and clay. Claymont clay bed is 1 to 3 m thick, brown, green, and
gray clay that weathers to distinctive brownish red. Bed is mostly clay,
partly pisolitic, and has scattered quartz grains in it. Locally,
supports large-scale clay operation. Upper part of unit above Claymont
clay bed is diverse section of marine and nonmarine sandstone,
siltstone, and conglomerate, and includes Serrano clay bed. Latter is
about 1 m thick, pale gray to white, and composed of nearly equal
amounts plastic clay and quartz. In addition to clay, upper part of
section contains carbonaceous shale and lignite beds. Thicker lignite
beds were locally mined for fuel. Upper part of unit also contains
abundant marine mollusks. Some eastern exposures of formation contain
distinctive and diagnostic Paleocene *Turritella pachecoensis.* Locally
basal conglomerate is divided and labeled Tsicg. Locally the Serrano
Clay is divided and labeled Tsis

Kwl **Williams and Ladd Formations, undifferentiated (upper
Cretaceous)**---Sandstone, siltstone, and conglomerate

**Williams Formation (upper Cretaceous)**---Sandstone and conglomeratic
sandstone. Named by Popenoe (1937, 1942) for exposures near mouth of
Williams Canyon in northern Santa Ana Mountains. He divided unit into
Pleasants Sandstone Member and Schulz Ranch Member. Woodring and Popenoe
(1945) renamed Schulz Ranch Member the Schulz Ranch Sandstone Member,
which was further subdivided into Schulz Ranch Sandstone Member and
Starr Member (Morton, and others, 1979). Later the name Schulz Ranch
Sandstone Member was shortened dropping "Sandstone" (Morton, and others,
1979). Formation consists of very resistant, cliff-forming, white to
brownish-gray, massive-bedded, poorly sorted feldspathic sandstone,
pebbly sandstone, and conglomeratic sandstone. Basal part of section
includes conglomerate. Locally contains siltstone beds, 3 to 8 m thick,
interbedded with conglomeratic sandstone. Calcite cemented spheroidal
concretions a few centimeters to a meter in diameter found locally.
Unconformably rests on Holz Shale Member of Upper Cretaceous Ladd
Formation. Includes:

Kwps **Pleasants Sandstone Member**---Marine sandstone Upper part is
poorly bedded, white to pale gray, feldspathic sandstone, which
generally is coarser grained than sandstone in lower part. Lower part is
sandstone and thin-bedded, biotite- and muscovite-bearing sandstone.
Massive sandstone contains biotite and black carbonaceous fragments and
scattered conglomerate lenses. Fossiliferous concretions are common.
Just south of Mojeska in northeastern El Toro 7.5' quadrangle the upper
part of the Pleasants Sandstone Member is a coarse-grained conglomeratic
sandstone (Kwps~1~)

Kwsr **Schulz Ranch Member**---Marine sandstone and conglomerate.
Sandstone typically coarse grained white- to brownish gray. Most is
massive; less commonly crossbedded. Contains scattered matrix-supported
pebbles and cobbles and sparse siltstone interbeds. Erosionally
resistant; forms prominent cliffs. Locally subdivided into Upper Schulz
Ranch (Kwsru), consisting of gray-white, coarse- to fine-grained, thin
bedded to massive, slightly to moderately consolidated conglomeratic
sandstone that grades down section into a lower unit (Kwsl). This lower
unit consists of light olive-gray siltstone that is well bedded, well
consolidated and is underlain by and interfingers with crudely bedded,
well to massive silty conglomerate and very coarse-cobble fanglomerate

Kwst **Starr Member**---Fanglomerate and sandstone. Starr Member is
nonmarine, pale gray, deeply weathered fanglomerate and interbedded
white friable sandstone. Most clasts are deeply weathered biotite
granitoids, but some are from Jurassic Bedford Canyon Formation and
Cretaceous Santiago Peak Volcanics. Interfingers with Schulz Ranch
Member

Kl **Ladd Formation** **(upper Cretaceous)**---Conglomerate, sandstone,
siltstone, and shale. Named by Popenoe (1942) for exposures just west of
mouth of Ladd Canyon, northern Santa Ana Mountains. Popenoe divided
formation into Baker Canyon Conglomerate Member and Holz Shale Member.
Includes:

Klhs **Holz Shale Member**---Interbedded marine shale, siltstone,
sandstone, and localized conglomerate beds. Sandstone beds are mostly
massive, but locally crossbedded. Unit contains 5 cm to 1 m calcite
cemented concretions. Foraminifera are widespread and megafossils
abundant in places. Except for resistant conglomerate beds, Holz Shale
weathers to form smooth rounded slopes. Unit includes prominent zone of
concentrated sandstone and conglomerate beds (Klhsc)

Klbc **Baker Canyon Conglomerate Member**---Marine and locally
nonmarine(?) conglomerate. Lower part is gray conglomerate containing
clasts up to 2 m across, derived mainly from granitic and volcanic
rocks. Granitic clasts appear to be from Cretaceous Peninsular Ranges
batholith and volcanic clasts from Cretaceous Santiago Peak Volcanics.
Upper part of conglomerate is brown conglomeratic sandstone and pebble
conglomerate. Sparse sandstone beds contain abundant mollusk shells.
Conglomerate is similar to conglomerate of underlying Trabuco Formation,
and locally interfingers with it. Pelecypods indicate deposition in
primarily shallow-water environment

Ktr **Trabuco Formation (upper Cretaceous)**---Unfossiliferous, mainly
brown to maroon, massive, nonmarine conglomerate with local sandstone
and siltstone beds (Popenoe, 1941). Packard (1916) named Trabuco
Formation for exposures in Harding Canyon, 4.8 km north of Trabuco
Canyon in northern Santa Ana Mountains. Clasts, up to 1 m in diameter,
but mostly range from 8 to 15 cm. Locally derived from Cretaceous
Peninsular Ranges batholith, Cretaceous Santiago Peak Volcanics, and
from meta-siltstone and sandstone of Jurassic Bedford Canyon Formation.
Trabuco Formation rests unconformably on Santiago Peak Volcanics and
Bedford Canyon Formation. Locally divided into an upper unit, labeled
Ktru, that consists of reddish-brown, thoroughly weathered bouldery
conglomerate, and a lower unit that consists of light brownish-gray
fanglomerate, labeled Ktrl. Clast size is larger in the lower unit with
the largest clasts as much as 2.4 m

## *Rocks of the Peninsular Ranges batholith*

Klct **Tonalite of Lamb Canyon (Cretaceous)**---Massive to faintly
foliated hornblende biotite tonalite. Informally named here for
exposures in headward part of Lamb Canyon in the southwest corner of the
Beaumont 7.5' quadrangle, just northeast of the northeast corner of the
Santa Ana 30'x60' quadrangle. Included in Lakeview Mountain tonalite by
Larsen (1948). Rock is characterized by relatively abundant sphene
crystals. Weathers to form landscape of very large boulders. Emplacement
age, based on Pb/U composition of zircon is 94 Ma (W.R. Premo, per.
commun., 1999)

Kmeg **Granite of Mount Eden** **(Cretaceous)**---White to pale gray,
leucocratic, medium- to coarse-grained, massive to foliated granite.
Informally named here for exposures in vicinity of Mount Eden (El Casco
and Lakeview 7.5' quadrangles). Included within the Perris quartz
diorite by Dudley (1935) and the Lakeview Mountain tonalite by Larsen
(1948). Characterized by muscovite and small bright red garnets.
Comprises pluton at Mount Eden and forms sills and dikes in metamorphic
rocks to southeast. Dikes and sill rocks are mostly well foliated,
concordant with foliation in surrounding metamorphic rocks

Kthgd **Granodiorite of Tucalota Hills (Cretaceous)**---Elongate pluton
comprised of massive, light-colored biotite granodiorite. Informally
named here for Tucalota Hills (eastern part of Bachelor Mountain 7.5'
quadrangle), which are underlain by the granodiorite. Included within
Woodson Mountain granodiorite by Larsen (1948)

Klt **Tonalite near mouth of Laborde Canyon (Cretaceous)**---Intensely
fractured biotite hornblende tonalite. Informally named here for
exposures just west of mouth of Laborde Canyon (northeast corner of
Lakeview 7.5' quadrangle). Fault bounded small discontinuously and
poorly exposed tonalite adjacent to Claremont fault. Fairly dark,
foliated tonalite having relatively large amounts of hornblende and
abundant, thin, small mesocratic inclusions

Khqd **Hypersthene quartz diorite (Cretaceous)**---Highly mafic,
hypersthene quartz diorite. Exposed on two small hills between Ryan
Airport and State highway 74 (Winchester 7.5' quadrangle). Dark-gray,
massive, fine- to medium-grained, homogeneous appearing
hypersthene-biotite quartz diorite. Distinguished by relatively high
color index, small grain size, lack of inclusions, and abundant
hypersthene. Intrusive into monzogranite of Tres Cerritos

Ktcg **Monzogranite of Tres Cerritos (Cretaceous)**---Medium- to
coarse-grained, foliated to subgneissic, subporphyritic biotite
monzogranite. Informally named here for exposures in eastern part of
Tres Cerritos (eastern part of the Lakeview 7.5' quadrangle). Included
within Perris quartz diorite by Dudley (1935) and within Bonsall
tonalite by Larsen (1948). Pale tan weathering, leucocratic, containing
potassium feldspar crystals up to 2.5 cm in length. Biotite comprises
about 5 percent of rock inmost of unit; locally as high as 10 percent.
Biotite typically forms groups of small plates. In gneissic parts of
unit, biotite occurs as coating on s-surfaces. Oligoclase margins are
commonly myrmekitic where plagioclase is in contact with potassium
feldspar. Includes segregation bodies of aplitic- and granitoid-textured
rock, and at south end of Tres Cerritos, several small masses of biotite
schist

**Lakeview Mountains pluton (Cretaceous)**---Composite pluton composed
mainly of biotite-hornblende tonalite in the Lakeview and adjacent parts
of the Winchester and Perris 7.5' quadrangles. Named Lakeview
quartz-hornblende diorite by Dudley (1935) and Lakeview Mountain
tonalite by Larsen (1948). Larsen's usage of Lakeview Mountain tonalite
included much of granitic and metamorphic rocks in Mount Eden area, and
a variety of granitic rocks within San Jacinto Mountains and in area
south of Hemet. Morton (1969) restricted usage to pluton underlying most
of Lakeview Mountains and southern part of the Bernasconi Hills as
originally used by Dudley (1935). Zircon age of tonalite is 100 Ma~id~
and 98 Ma~ip~. ^40^Ar/^39^Ar age of hornblende is 98.6 and conventional
K/Ar age of biotite is 92.4 Ma (Pb/U age, W.R. Premo per. commun., 1999
and Ar/Ar age, L. W. Snee, per. commun., 1999, K/Ar age, F.K. Miller
per. commun., 1980). Includes:

Klmp **Pegmatite dikes**---Granitic pegmatites common in central part of
pluton and rare elsewhere in the pluton, except for small area near
southern margin. Most pegmatite dikes are steeply dipping and
tabular-shaped. Dikes are compositionally and texturally zoned, having
an outer wall zone of coarse- and extremely coarse-grained intergrowths
of alkali feldspar, quartz, and biotite, in which graphic intergrowths
of quartz and alkali feldspar are common. Within outer wall zone, is
inner core zone of extremely pegmatitic-textured alkali feldspar,
quartz, muscovite, schorl, and garnet. Large pegmatite dikes have
intermediate zone similar to inner zone but crystals are larger. Single
tourmaline crystals in larger dikes are up to 1 m in length. Cores of
larger dikes are massive quartz and giant perthite crystals. Epidote and
zeolite minerals are widespread minor constituents. A distinctive
assemblage of uncommon minerals occurs within larger pegmatite dikes
includes bismutite, beyerite, pucherite, bismuthinite, microlite,
yttrocolumbite-tantalite, cyrtolite, allanite, pyrochlore, sphalerite,
chalcocite, uranophane, xenotime, and thorogummite

Klmt **Tonalite**---Gray, medium- to coarse-grained, massive to
foliated, biotite hornblende tonalite lacking potassium feldspar. Most
abundant rock type in Lakeview pluton. Tonalite characterized by
presence of ubiquitous schlieren, and in much of body, tonalite is
essentially all schlieren. Schlieren renders tonalite extremely
heterogeneous at outcrop scale producing rocks that ranges in
composition from leucocratic to melanocratic. Schlieren range in shape
from relatively tabular to wispy layers and in size from a few
centimeters in width to sizes mappable at 1:24,000 (Morton, 1969; 1972;
Morton and others, 1969). Mineralogic composition of tonalite without
variability introduced by schlieren is, quartz 13 to 32 percent,
plagioclase (andesine) 34 to 70 percent, biotite 7 to 22 percent and
hornblende 4 to 29 percent. Mafic minerals average about 25 percent of
tonalite. Accessory minerals are apatite, zircon, magnetite-ilmenite,
and sphene. Colorless small masses of cumingtonite form central parts of
some hornblende crystals. Ellipsoidal melanocratic inclusions are common
and widespread. Dark gray tonalite along southern contact of pluton,
forms thin septa of foliated, porphyritic looking rock which results
from stumpy, black hornblende prisms set in a fine-grained granoblastic
matrix of biotite, quartz, and plagioclase. Texture is interpreted as a
protoclastic. Length of septa is parallel to pluton contact

Klml **Leucocratic rocks**---Elongate masses of white rock composed of
andesine and quartz appear to be mega-scale leucocratic schlieren. These
leucocratic masses are texturally like typical Lakeview Mountains
tonalite, except overall grain size is slightly reduced, due to dearth
of mafic minerals which are generally larger than other minerals in
rock. Biotite and hornblende, where present in small amounts, are
extremely poikilitic. Muscovite, a rare primary(?) constituent, occurs
as small crystals interstitial to plagioclase

Klmm **Melanocratic rocks**---Lenticular masses of melanocratic and
hypermelanic rock that includes compositions ranging from about 50
percent biotite and hornblende to rock that is essentially all biotite
and hornblende. Scattered throughout most of pluton, but concentrated in
central and northeast part. These bodies are interpreted to be very
large-scale schlieren-like masses; minerals are same as those of typical
Lakeview Mountains tonalite, but slightly larger in grain size

Klmtg **Lakeview Mountains tonalite and granodiorite,
undifferentiated**---Mixed Lakeview Mountains tonalite and granodiorite
along margin of Lakeview Mountains pluton in southern part of Bernasconi
Hills (Perris 7.5' quadrangle)

Klmc **Comb-layered gabbro**---Along southern margin of pluton is
elongate body of comb-layered gabbro (Moore and Lockwood, 1973). Gabbro
consists of folded layers of alternating labradorite-rich gabbro and
hornblende or augite-rich rock. Labradorite crystals are elongate normal
to layering, and mostly branch upwards to form feather-like crystals.
Brown-weathering

Klmg **Hypersthene hornblende gabbro**---Small masses of hypersthene
hornblende gabbro scattered through pluton, but slightly concentrated in
central and northeastern parts. At a distance, readily discernible from
tonalite, as they are darker and weather to form brown outcrops. Masses
are elongate and range in length from 1 to more than 100 m

Krct **Tonalite of Reinhardt Canyon pluton
(Cretaceous)**---Biotite-hornblende tonalite containing abundant and
varied inclusions. Informally named Reinhardt Canyon pluton here for
arcuate-shaped band of exposures that define the body in Reinhardt
Canyon area east side of Lakeview Mountains pluton (Lakeview 7.5'
quadrangle). Pluton included in Perris quartz diorite by Dudley (1935)
and in Bonsall tonalite by Larsen (1948). Tonalite is gray, medium
grained, generally well foliated. Biotite and hornblende occur in
subequal amounts, aggregating 15 to 20 percent of rock. Very sparse
untwinned potassium feldspar occurs locally. Accessory minerals are
zircon, magnetite-ilmenite, apatite, sphene, and secondary white mica,
epidote, and chlorite. Unit characterized by moderate to abundant dark,
discoidal to plate-shaped and elongate-shaped inclusions; the
near-vertical elongate-shaped inclusions gives rise to locally a
pronounced large-scale lineation. Except for southern 460 m of western
boundary, pluton is gradational into Lakeview Mountains pluton; along
southern 460 m of western border, two plutons are separated by a thin
septum of gneissic rock. Most of eastern contact dips steeply to east or
is nearly vertical; locally it is hair-line sharp. Age relations between
pluton and Lakeview Mountains pluton are ambiguous. Tonalite of
Reinhardt Canyon pluton is distinguished from tonalite of Lakeview
Mountains pluton by finer grain size, rare schlieren, and more abundant
and more attenuated inclusions

Kbpg **Monzogranite of Bernasconi Pass** **(Cretaceous)**---Irregularly
porphyritic biotite and biotite-hornblende tonalite. Included by Larsen
(1948) with rocks he referred to as "granodiorite west of Lakeview", and
by Dudley (1935) with Perris quartz diorite. Informally named here for
exposures in hills south of Bernasconi Pass (Perris 7.5' quadrangle).
Buff- to tan-weathering, medium-grained, hypidiomorphic-granular to
porphyritic, foliated biotite and biotite-hornblende monzogranite.
Potassium feldspar phenocrysts up to 2.5 cm in length appear to be late
forming, and in part replace parts of inclusions. Contains common to
abundant, well-oriented, discoidal to plate-shaped melanocratic
inclusions. In places rock is migmatitic, composed of nearly equal
amounts monzogranite and inclusion-like rock. Weathers to form large
boulders, many of which are several meters in length. Southern part of
monzogranite contains widespread aplitic dikes. Includes:

Kbpm **Migmatitic rocks within Monzogranite of Bernasconi
Pass**---Relatively large bodies of migmatitic rock within Kbpg
consisting of about equal amounts monzogranite and mafic rocks, which
resemble inclusions and have defuse contacts

Ktbh **Tonalite of Bernasconi Hills (Cretaceous)**---Gray,
medium-grained, massive- to crudely foliated, hypidiomorphic-granular
biotite hornblende tonalite. Informally named here for series of small
elongate tonalite composition plutons exposed in Bernasconi Hills
(Perris 7.5' quadrangle). Included within Perris quartz diorite by
Dudley (1935) and within Bonsall tonalite by Larsen (1948). Biotite and
hornblende occur in subequal amounts averaging several percent each.
Potassium feldspar comprises up to several percent of tonalite. Oriented
mafic minerals define foliation. Contains abundant, widespread
fine-grained mafic inclusions ranging in size from 2.5 to 30 cm.
Inclusions are equant to elongate; elongation parallel to foliation in
enclosing tonalite. Unit weathers to form slopes densely covered by
gray, well-rounded boulders of disintegration

**Box Springs plutonic complex (Cretaceous)**---Box Springs plutonic
complex is an elliptical, flat-floored basin-shaped granitic complex
centered on the Box Springs Mountains (Riverside East and Sunnymead 7.5'
quadrangles); it is apparently lower part of a granitic diapir. Complex
consists of core of essentially massive to indistinctly layered biotite
tonalite surrounded by a layer of foliated biotite granodiorite to
tonalite. Outward from biotite granodiorite to tonalite is,
respectively, a discontinuous layer of foliated, heterogeneous
porphyritic granodiorite, followed by uniform porphyritic granodiorite.
Other compositionally and texturally diverse granitic rocks also occur
within the complex, but in relatively small amounts. All rocks of
complex were included in Perris quartz diorite by Dudley (1935) and in
Bonsall tonalite by Larsen (1948). Except for dike rocks, units are
described in general order from core outward. Includes:

Kp **Granitic pegmatite dikes**---Most are relatively small, typically
tabular granitic pegmatite dikes. Subordinate large dikes are
compositionally and texturally zoned, having an outer border and wall
zone of coarse- and extremely coarse-grained intergrowths of alkali
feldspar, quartz, and biotite. Outer zone encloses core of alkali
feldspar and quartz. In some dikes, intermediate zone consists of alkali
feldspar, quartz and a variety of accessory minerals including garnet,
tourmaline, columbite-tantalite, and monazite

Kbt **Biotite tonalite**---Massive, fine- to medium-grained,
equigranular biotite tonalite that forms core of Box Springs plutonic
complex. Much of tonalite has compositional layering that is faintly to
moderately developed and is very regular. Rocks contain about 35 to 40
percent quartz and 6 to 12 percent biotite. Hornblende is absent and
potassium feldspar ranges from 1 to 4 percent. Mineral alignment is
poorly developed or absent, but much of rock has incipient to
well-developed primary layering defined by mineral concentrations. Unit
contains sparse equant- to elliptical-shaped, fine-grained, mesocratic
inclusions; some have relatively mafic rims. Inclusions tend to be
aligned parallel to compositional layering. Zircon age of rock is 98.6
Ma~id~ and 100.4 Ma~ip~ (Pb/U ages, W.R. Premo per. commun., 1999)

Kbfg **Biotite granodiorite and tonalite**---Light gray, and medium- to
coarse-grained foliated biotite granodiorite and tonalite. Contains 25
to 35 percent quartz, 8 to 15 percent biotite, and minor hornblende.
Potassium feldspar occurs as small interstitial grains and sparse
subhedral phenocrysts up to 1.5 cm in diameter. Potassium feldspar
appears to progressively decrease inward within unit; tonalite most
abundant in inner part. Mesocratic discoidal inclusions oriented
parallel to foliation are common, but not abundant. Grades into biotite
tonalite unit (Kbt)

Kbfgi **Biotite granodiorite and tonalite containing abundant
inclusions**---Biotite granodiorite and tonalite that contains abundant
discoidal, mafic inclusions; restricted to east side of complex

Kbhg **Heterogeneous porphyritic granodiorite**---Heterogeneous
porphyritic granodiorite and subordinate tonalite. In most places
surrounds biotite granodiorite and tonalite unit (Kbfg). Pinches out
along west side of complex. Granodiorite is medium to coarse grained,
light gray, foliated, and porphyritic. Contains plagioclase, 25 to 35
percent quartz, and 10 to 15 percent mafic minerals, chiefly biotite and
subordinate hornblende. Mafic minerals unevenly distributed imparting
heterogeneous appearance to rock. Subhedral potassium feldspar crystals
are up to 2.5 cm in length. Widespread discoidal mesocratic inclusions
oriented parallel to foliation. Dikes and sills of leucocratic granite
and pegmatite are abundant

Kbhg~1~ **Layered heterogeneous porphyritic
granodiorite**---Heterogeneous porphyritic granodiorite that has
pronounced layering defined chiefly by variations in grain size

Kbg **Porphyritic granodiorite**---Coarse-grained, light gray, foliated,
porphyritic biotite granodiorite and subordinate tonalite. In most
places grades into heterogeneous porphyritic granodiorite unit (Kbhg).
Groundmass is plagioclase, quartz (30 to 40 percent), and mafic minerals
(5 to 10 percent). Mafic minerals are biotite and sparse hornblende,
which are more evenly distributed than in heterogeneous granodiorite
(Kbhg). Subhedral potassium feldspar phenocrysts are up to 2.5 cm in
length. Discoidal mesocratic inclusions are oriented parallel to
foliation

Kbft **Biotite-hornblende tonalite**---Light- to medium gray, medium- to
coarse-grained, foliated tonalite. Contains 20 to 25 percent quartz and
about 25 percent biotite and hornblende in subequal amounts. Hornblende
and biotite occur as ragged crystals. Potassium feldspar present, but
sparse. Anhedral, interstitial sphene is conspicuous accessory mineral.
Contains abundant, fine-grained, mesocratic, ellipsoidal- to
discoidal-shaped mafic inclusions aligned parallel to foliation

Kbht **Heterogeneous biotite tonalite**---Light-gray, inequigranular,
medium- to coarse-grained, foliated biotite tonalite; restricted to
northwestern Box Springs Mountains. Dominant rock type is leucocratic
tonalite, containing only 1 to 4 percent biotite, which occurs as thin,
subhedral plates, irregularly concentrated and aligned to produce a
wispy, swirling foliation. Leucocratic tonalite encloses pods and lenses
of tonalite containing about 15 percent biotite as large ragged plates.
Both types of tonalite contain abundant quartz (30 to 40 percent) and
very sparse potassium feldspar (1 percent or less). Contains dispersed,
mesocratic, discoidal inclusions. Granitic pegmatite dikes are abundant

Kbgt **Heterogeneous granodiorite and tonalite**---Light- to
medium-gray, medium- to coarse-grained, texturally heterogeneous,
foliated, hornblende-biotite tonalite and granodiorite; restricted to
northern Box Springs Mountains near Pigeon Pass. Common discoidal,
mesocratic inclusions oriented parallel to foliation

Kba **Amphibolitic gabbro**---Dark- gray to-black, fine- to
medium-grained, foliated, hornblende-rich amphibolitic gabbro forming
lenses and elongate masses within heterogeneous granodiorite and
tonalite (Kgbt). Foliation is parallel to foliation in that unit

**Val Verde pluton** **(Cretaceous)**---Large, relatively uniform pluton
composed of biotite-hornblende tonalite extending from the Perris 7.5'
quadrangle north to the Riverside East and West 7.5' quadrangles. Termed
Perris quartz diorite by Dudley (1935), Val Verde tonalite by Osborn
(1939), and included within Bonsall tonalite by Larsen (1948). Name Val
Verde is adopted here based on detailed study of Osborn (1939) near Val
Verde, Steele Peak 7.5' quadrangle. Name Val Verde is from former
settlement and railway siding midway between Perris and Riverside.
Apparently steep-walled Val Verde pluton is eroded to mid-pluton level.
Emplacement age of the pluton is 105.7 Ma~id~. ^40^Ar/^39^Ar age of
hornblende is 100 Ma, biotite 95 Ma and potassium feldspar 88.5 Ma (Pb/U
ages, W.R. Premo per. commun., 1999 and Ar ages, L. W. Snee, per.
commun., 1999). Includes:

Kvt **Val Verde tonalite**---Gray-weathering, relatively homogeneous,
massive- to well-foliated, medium- to coarse-grained,
hypautomorphic-granular biotite hornblende tonalite; principal rock type
of Val Verde pluton. Contains about equal amounts biotite and
hornblende, quartz and plagioclase. Potassium feldspar generally
present, but constitutes less than two percent of rock. Where present,
foliation typically strikes northwest and dips moderately to steeply
northeast. Northern part of pluton contains younger, intermittently
developed, northeast-striking foliation. In central part of pluton,
tonalite is mostly massive, and contains few segregational masses of
mesocratic to melanocratic tonalite. Elliptical- to pancake-shaped,
meso- to melanocratic inclusions are common

Kvtk **Potassium feldspar-bearing tonalite**---Thin layer of
heterogeneous biotite-hornblende tonalite containing more than two
percent, but less than 10 percent potassium feldspar; located along part
of contact with biotite schist on west side of pluton

Kvti **Inclusion-rich tonalite**---Subequal amounts of
biotite-hornblende tonalite and melanocratic inclusion-like rock. Rock
has migmatitic appearance

Kgr **Granophyre (Cretaceous)**---Gray, aphanitic to very fine-grained,
granophyric textured granitic rock. Composed of granophyric intergrowths
of quartz and alkali feldspars. Contains some fine-grained pyrite which
oxidizes to give rock rusty appearance

**Green Acres gabbro complex (Cretaceous)**---Medium- to very
coarse-grained olivine-bearing gabbro that weathers gray to black. Named
for community of Green Acres on southeast side of Lakeview Mountains
(Morton, 1969) (northern part of the Winchester 7.5' quadrangle).
Included within San Marcos gabbro by Larsen (1948). Most gabbro is
hypidiomorphic-granular; poikilitic rock is common and porphyritic rock
less common. Weathers to form semi-smooth slopes littered with scattered
small boulders. Includes rare orbicular gabbro and protoclastic flaser
gabbro. Contains several small septa of quartzofeldspathic, biotite
quartz-feldspar, and graphitic schist. In northern part of gabbro
complex are a few occurrences of quartzo-feldspathic mylonite. Includes
common granitic pegmatite dikes; some andalusite-bearing dikes. One
granitic pegmatite dike in southern part of the complex contains masses
of gabbro converted to biotite-hydrobiotite-vermiculite with included
andalusite, some of which have cores of blue corundum crystals. Some of
the pegmatite dikes have been mylonitized. Color of decomposed gabbro
and soil derived from gabbro is typically dark red-brown. Includes:

Kgab **Heterogeneous mixture of olivine, pyroxene, and hornblende
gabbros**---Northern part of Green Acres gabbro complex is very
heterogeneous mix of gabbro, including olivine, pyroxene, and hornblende
gabbro intruded by quartz diorite and tonalite. Slopes covered with
gabbro rubble generally mask presence of quartz diorite and tonalite

Kgao **Olivine gabbro**---Southern half of Green Acres gabbro is mostly
olivine gabbro, which ranges from a few percent to about one-third
olivine (Fo~75~ to Fo~87~). Kelyphitic rims are common around olivine.
Anorthite (An~90~) makes up 30 to 90 percent of gabbro as anhedral to
subhedral, complexly twinned crystals. Stubby, anhedral orthopyroxene in
thin section is nearly colorless- to very pale-pink, and pleochroic,
commonly forming overgrowths of, or intergrowths with, clinopyroxene or
hornblende. Augite occurs as anhedral, tabular- to irregular-shaped,
colorless crystals, some of which contain schiller-like intergrowths of
a violet, platy, nearly opaque mineral. Augite is commonly mantled with
brown and (or) green hornblende. Hornblende occurs as both brown
hornblende and nearly colorless to very light green hornblende. Latter
occurs primarily in reaction rims (kelyphyitic rims) intergrown with
spinel around olivine; brown hornblende occurs most commonly as both
interstitial crystals and as subhedral crystals. Opaque minerals,
including magnetite, occur adjacent to olivine and as symplektitic
intergrowths with amphibole. Colorless- to light-green chlorite is
abundant in some protoclastic gabbro. Planar, vein-like
hornblende-spinel masses are locally common in gabbro having abundant
olivine. Small hornblende gabbro dikes are mineralogically similar to
that of enclosing olivine gabbro. Some dikes are fine- to
medium-grained, meso- to melanocratic hornblende gabbro; others consist
of porphyritic hornblende olivine gabbro

Kgah **Hornblende-rich gabbro**---Fine- to medium-grained, melanocratic
hornblende gabbro. In thin section, brown prismatic hornblende imparts a
nematoblastic texture to this gabbro. Typically consists of 46 percent
brown hornblende, 7 percent green hornblende, 9 percent clinopyroxene, 2
percent olivine, 34 percent calcic plagioclase, and 2 percent opaque
minerals

Kgat **Troctolite**---Small elliptical intrusion of distinctive rock
composed of about 45 percent anorthite (An~90~), 36 percent olivine
(Fo~85~), 11 percent clinopyroxene, 3 percent orthopyroxene, 2 percent
hornblende, 2 percent spinel, and about 5 percent iddingsite. Kelyphitic
rims mantle most olivine crystals. Large subhedral anorthitic
plagioclase crystals impart a slightly porphyritic texture to rock

Kgaa **Anorthositic gabbro**---Pale gray-weathering, leucocratic,
labradorite-anorthite gabbro. Anorthosite is composed essentially of
calcic plagioclase, containing small, variable amounts of olivine and
(or) pyroxene

Kgam **Metagabbro**---Several small bodies of metagabbro derived from
Green Acres gabbro are included within Lakeview Mountains tonalite and
granodiorite (Klmtg) in southern part of Lakeview Mountains. These
bodies contain abundant masses of chlorite and blue-green hornblende

**Gavilan ring complex (Cretaceous)**---Composite ring structure
consisting of a variety of granitic rocks that range from monzogranite
to tonalite (Steele Peak, Lake Mathews, and Elsinore 7.5' quadrangles).
Informally named here for exposures in Gavilan Plateau area (Steele Peak
and Lake Mathews 7.5' quadrangles). Western part of complex was termed
Estelle quartz diorite and eastern part included in Perris quartz
diorite by Dudley (1935). Western part of complex was termed Estelle
tonalite and eastern part was included within Bonsall tonalite by Larsen
(1948). Hypersthene is a characteristic mineral of many rocks in
complex. Based on texture, depth of erosion is greater in eastern part
of complex than in western part. Rocks on west side of the complex
commonly have hypabyssal texture and appear to grade into volcanic
textured rock. Several gold mines (e.g., Good Hope, Gavilan, and Santa
Rosa mines), which constituted Pinacate mining district (Sampson, 1935),
are located within complex. Gold apparently occurred in arsenopyrite
bearing quartz veins. Located in center of ring complex, but not part of
it, is near-circular Arroyo del Toro pluton. Includes:

Kgg **Hypersthene monzogranite**---Massive hypersthene monzogranite;
nearly black where fresh, dark-brown-weathering. Contains biotite,
hornblende, hypersthene, and clinopyroxene as mafic phases. Rock has
sparse small mesocratic inclusions, which are commonly lighter colored
than monzogranite. Quarried as "black granite" building stone in past.
Zircon age is 109 Ma~id~ and 106 Ma~ip~. ^40^Ar/^39^Ar age of biotite is
104.5 Ma and potassium feldspar 99.3 Ma

Kgt **Massive textured tonalite**---Brown-weathering, massive,
relatively heterogeneous, hypersthene-bearing biotite-hornblende
tonalite. Most abundant rock type in complex. Equant-shaped mesocratic
to melanocratic inclusions are common. Zircon age is 112.9 Ma~id~ and
113.6 Ma~ip~ (Pb/U ages, W.R. Premo per. commun., 1999)

Kgtf **Foliated tonalite**---Gray, medium-grained, foliated
biotite-hornblende tonalite containing discoidal mafic inclusions. Most
of tonalite lacks hypersthene. Unit restricted to northern part of
complex

Kgti **Tonalite containing abundant mesocratic inclusions**---Moderately
fine-grained tonalite containing abundant, small, platy mesocratic
inclusions. Tonalite lacks hypersthene, which is common to most of
complex. Zircon age is 108.6 Ma~id~ and 109.1 Ma~ip~. ^40^Ar/^39^Ar age
of hornblende is 106 Ma, biotite 103 Ma and potassium feldspar 98.5 Ma
(Pb/U ages, W.R. Premo per. commun., 1999 and Ar ages, L. W. Snee, per.
commun., 1999)

Kgh **Hypabyssal tonalite**---Massive, hypabyssal-textured tonalite and
lesser granodiorite in southwestern part of complex. Contains small,
equant shaped mesocratic inclusions

Kgct **Coarse-grained biotite-hornblende tonalite**---Massive to
foliated, relatively light colored, coarse-grained tonalite that
weathers to form very large boulders of disintegration

Kght **Heterogeneous tonalite**---Medium-grained, foliated
biotite-hornblende tonalite, containing moderately abundant to abundant,
small, biotite-hornblende granodiorite intrusions. Rock contains
moderately abundant elliptical- to pancake-shaped, mesocratic to
melanocratic inclusions

Kmp **Micropegmatite granite (Cretaceous)**---Named by Larsen (1948) for
pink-tinted, leucocratic outcrops of granite (Corona North quadrangle).
Granite is very distinctive in thin section due to micropegmatitic
texture

Kmpc **Micropegmatite and granodiorite of Cajalco pluton,
undifferentiated (Cretaceous)**---Mixed unit of micropegmatite and
massive granodiorite to monzogranite. Related to, but not mapped as part
of Cajalco pluton

Ktd **Tonalite dikes of Mount Rubidoux (Cretaceous)**---Light gray,
fine- to medium-grained, massive to foliated,
hornblende-clinopyroxene-hypersthene-biotite tonalite (Riverside West
7.5' quadrangle). Contains discoidal mafic inclusions

Kmrg **Granite of Mount Rubidoux (Cretaceous)**---Massive granite
characterized by coarse grain size and presence of hypersthene and
fayalitic olivine (Riverside West 7.5' quadrangle). Termed "coarse
leucogranite of Rubidoux Mountain" by Larsen (1948). Inequigranular;
average grain size 5 mm; Potassium feldspar crystals are up to 12 mm in
length. Biotite and hornblende aggregate about 5 percent and hypersthene
and olivine occur as sparse constituents. Most of granite is devoid of
inclusions. Zircon ages are 109 Ma~id~ and 107.3 Ma~ip~ and
^40^Ar/^39^Ar age of biotite is 98 Ma and potassium feldspar 93 Ma (Pb/U
ages, W.R. Premo per. commun., 1999 and Ar ages, L. W. Snee, per.
commun., 1999)

Krg **Granite of the Riverside area (Cretaceous)**---Medium- to
coarse-grained, massive- to faintly-foliated, leucocratic biotite
granite (Riverside East and West 7.5' quadrangles). Contains about 1 to
3 percent biotite. Inclusions are sparse or absent except locally in
western part of body where granite contains 2 to 8 percent biotite and
sparse to abundant inclusions of quartz diorite, granodiorite, and
fine-grained mafic rock. At Mount Rubidoux, rocks contain sparse
hypersthene and fayalitic olivine and moderately abundant equant
inclusions of dark-gray fine-grained rock. Rock at Mount Rubidoux termed
"fine leucogranite of Rubidoux Mountain" by Larsen (1948)

Kmhg **Mount Hole Granodiorite (Cretaceous)**---Massive, light colored
hornblende-biotite granodiorite. Named by Larsen (1948) for exposures at
Mount Hole (Corona North 7.5' quadrangle). Weathers to form large
boulders of disintegration

Klst **La Sierra Tonalite (Cretaceous)**---Moderately dark-colored,
massive biotite tonalite. Named by Larsen (1948) for exposures in the
vicinity of La Sierra (Corona North 7.5' quadrangle). Much of tonalite
is altered to secondary minerals, especially epidote and chlorite.
Includes some zones of tonalite thoroughly altered to epidote, quartz,
and chlorite and locally tourmaline and sulfide minerals

Katg **Granodiorite of Arroyo del Toro pluton (Cretaceous)**---Light
gray, medium-grained, massive, very homogeneous, and inclusion-free
biotite-hornblende granodiorite (Steele Peak and Elsinore 7.5'
quadrangles). Some of the rock in the western part of the pluton is
slightly porphyritic. Informally named here for Arroyo del Toro, located
in center part of pluton. Termed Steele Valley granodiorite by Dudley
(1935) and included by Larsen (1948) within Woodson Mountain
granodiorite. Near circular Arroyo del Toro is located in center of
Gavilan ring complex, but is not part of complex. Zircon ages of the
pluton are 108.6 Ma~id~ and 111 Ma~ip~. ^40^Ar/^39^Ar biotite age is
104.3 Ma and potassium feldspar 98.5 Ma (Pb/U ages, W.R. Premo per.
commun., 1999 and Ar ages, L. W. Snee, per. commun., 1999)

**Cajalco pluton (Cretaceous)**---Mostly biotite and biotite-hornblende
monzogranite and granodiorite (Lake Mathews and Corona North 7.5'
quadrangles). Informally named here for exposures in Cajalco area (Lake
Mathews 7.5' quadrangle). Rocks of Cajalco pluton were included within
Cajalco quartz monzonite by Dudley (1935) and within Woodson Mountain
granodiorite by Larsen (1948). Body is a shallow-level pluton emplaced
by magmatic stoping within largely volcanic and volcanoclastic rocks. It
is tilted eastward and eroded to progressively greater depths from west
to east. Upper part of pluton contains a very prominent halo of
tourmalinized rock. Zircon ages are 109.5 Ma~id~ and 112.6 Ma~ip~ (Pb/U
ages, W.R. Premo per. commun., 1999). Includes:

Kcto **Tourmalinized monzogranite and granodiorite**---Tourmalized
monzogranite and granodiorite. Also includes some tourmalinized volcanic
rock in western part of pluton. Tourmaline is extremely fine grained to
aphanitic. Tourmalinized rock ranges from incipient
fracture-replacing-tourmaline, through tourmalinized mafic minerals, to
completely tourmalinized coal-black rock-bodies over hundred meters in
length. Northeast striking joints are preferential sites for most
extensively tourmalinized rock. Tourmaline sequentially replaces biotite
and hornblende followed in order by feldspar and quartz. All variations
in degree of replacement are found. Where only quartz remains as primary
mineral, tourmalinized rock is distinctive, white-dappled, black rock
resembling porphyry. Tourmalinized rock contains small amounts of iron
sulfide(s) and very locally cassiterite. Tin was discovered about 1853
in a large mass of tourmalinized rock in Eagle Valley area (Lake Mathews
7.5' quadrangle). Cassiterite-bearing rock was intermittently mined from
1860 to about 1892 (Sampson, 1935). Over 250,000 pounds of tin was
smelted in 1891-1892. Only rock that is essentially all tourmaline, is
mapped as Kcto. Tourmalinized rock is very resistant to erosion and
stands out as small, bold, black hills, locally termed tourmaline
blow-outs. Cobbles of tourmaline rock are locally abundant in Miocene
Lake Mathews Formation. Very locally pink, radiating, fibrous to
prismatic masses of dumortierite occur rather than tourmaline. One
dumortierite-bearing dike located in Temescal Canyon contains large
sprays of radiating prismatic dumortierite

Kcg **Monzogranite**---Most of western part of pluton is medium-grained,
equigranular, hypautomorphic-granular to subporphyritic monzogranite and
subordinate granodiorite. Includes variable amounts of angular
inclusions, mostly, if not entirely derived from stoping of Estelle
Mountain volcanics. Number, size, and reliability of identity of
inclusion parent rock increases from east to west. In western part of
pluton included masses of volcanic rock comprise large volume of pluton.
In northern and northeastern part of pluton stoped masses of hornblende
gabbro are abundant. Unit includes relatively fine-grained leucogranite,
especially in area northwest of Lake Mathews

Kcgd **Granodiorite**---Most of eastern part of pluton is
medium-grained, equigranular, hypautomorphic granular granodiorite and
subordinate monzogranite. Granodiorite includes variable amounts of
angular inclusions

Kct **Tonalite---**Masses of mafic biotite-hornblende tonalite.
Represents deepest part of pluton

Kcgq **Granodiorite and quartz latite, undifferentiated**---Nearly equal
amounts of plutonic and volcanic rock; in some areas, unit is mostly
quartz latite. Found near intrusive contacts with Mesozoic volcanic
rocks

Kcgb **Granodiorite and gabbro, undifferentiated**---Mixed granodiorite
and gabbro. In northern and northeastern part of pluton granitic rock
contains high concentrations of stoped hornblende gabbro. In some areas
granite and gabbro are intimately intermixed producing very
heterogeneous rock

Kgbd **Gabbroic dikes, Domenigoni Valley area
(Cretaceous)**---Relatively fine-grained, massive, black, hornblende
gabbro occurs as thin (few meters thick) dikes in Domenigoni valley area
(Romoland and Winchester 7.5' quadrangles). Dikes cut both granodiorite
of Domenigoni Valley pluton and adjacent metamorphic rocks

**Domenigoni Valley pluton** **(Cretaceous)**---Massive, isotropic,
gray, medium-grained, biotite hornblende granodiorite and tonalite
(Winchester and Romoland 7.5' quadrangles). Larsen (1948) used name
Domenigoni granodiorite for exposures in Domenigoni Valley area, but
included western part of pluton in his Bonsall tonalite unit. Erosion
exposes only upper part of pluton. Pluton consists of two parts
separated by pendant of metasedimentary rock and gabbro. Foliated rock
found only in southeastern part of pluton. Unit contains moderately
abundant to abundant, equant-shaped, mesocratic inclusions, which are
sparse or lacking around margins of pluton. Two relatively consistent,
steeply dipping, joint sets are present throughout pluton; one strikes
northeast, other northwest. Dacite-quartz latite dike swarm was emplaced
along northwest striking joint set. Contact between pluton and older
rocks is knife-edge sharp. Grain size of granodiorite-tonalite is
unchanged at contact. At most places there is little change in
mineralogy or fabric of host rocks, except local deflection of
schistosity within a few meters of contact. In some places in
northeastern part of pluton schistosity is deflected up to 60 to 90 m
from contact. Southeastern part of the pluton, however, coincides with
westward deflection of metamorphic foliation to parallel contact of
pluton. Apophysis of pluton is well exposed in highway cut on US 215 at
Sun City. Rock there contains abundant inclusions of contact
metamorphosed impure quartzite, lithic graywacke, and phyllite.
Siliceous carbonate bearing inclusions consist of pyroxene hornfels
mineral assemblages including wollastonite, diopside, and grossularite.
East of Quail Valley small apophyses of granodiorite occur in thoroughly
fragmented quartz-rich metasedimentary rock that is pervasively
penetrated by smaller irregular masses of granodiorite. Includes:

Kld **Quartz latite dikes**---Light- to dark-gray, fine-grained, massive
to well-foliated, biotite, biotite-hornblende, and hornblende quartz
latite. Some dike rock contains small needle-like hornblende crystals.
Swarm of quartz latite dikes occur in eastern part of Domenigoni Valley
pluton. A few dikes extend into metasedimentary country rock and some
occur entirely within metasedimentary rocks. Dikes are more resistant to
erosion than the enclosing rock and form conspicuous ribs and walls.
Included as part of Domenigoni Valley pluton, because they are largely
restricted to pluton. Most are foliated in contrast to massive
granodiorite. Streaks of biotite, and less commonly oriented hornblende
crystals, give rise to pronounced and regular lineation

Kdvg **Granodiorite to tonalite of Domenigoni Valley**---Relatively
uniform, massive hornblende biotite granodiorite grading into tonalite.
This is principal rock type of Domenigoni Valley pluton. Contains some
mafic rich rocks in the southern part of the pluton. Common accessory
minerals are zircon, sphene, apatite, and magnetite-ilmenite. Minute
rutile crystals impart bluish opalescence to quartz. Small masses of
epidote and/or tourmaline rock occur locally and appear to replace
granodiorite to tonalite. Contains moderately abundant to abundant
equant mafic inclusions. Zircon age is 117.8 Ma~id~ and 112.8 Ma~ip~ and
^40^Ar/^39^Ar age of 104 Ma for biotite and 95.5 Ma for potassium
feldspar (Pb/U ages, W.R. Premo per. commun., 1999 and Ar ages, L. W.
Snee, per. commun., 1999)

Kgbf **Fine-grained hornblende gabbro, Railroad Canyon area
(Cretaceous)**---Fine-grained hornblende gabbro constituting dikes,
sills, and small elongate plutons. Emplaced in phyllite in Railroad
Canyon area (Elsinore 7.5' quadrangle)

**Paloma Valley ring complex (Cretaceous)**---Composite ring dike
intrusion. Named and described by Morton and Baird (1976) for exposures
in Paloma Valley area. Complex is located in the Murrieta, Romoland and
Elsinore 7.5' quadrangles. Included within Woodson Mountain granodiorite
and San Marcos gabbro by Larsen (1948). Ring complex consists of older,
elliptical in plan, single ring-dike and two subsidiary short-arced
dikes. A younger ring-set of thin dikes is largely within older ring
dike. Older dike consists of granodiorite and monzogranite with vertical
walls emplaced into gabbro by ring fracturing and magmatic stoping of
gabbro. Younger ring-dike consists of hundreds of granitic pegmatite
dikes. Most pegmatite dikes are 30 cm to over 1 m in thickness, and
define a domal ring-dike geometry in which outer dikes are moderately to
steeply outward dipping and pass inward to near horizontal dikes in
center. Spatially associated with younger dikes in center of complex,
are bodies of granophyre that contain stringers of granitic pegmatite.
Younger dikes are interpreted as products of volatile-rich magma that
filled a domal set of fractures resulting from cauldron subsidence.
Granophyre is interpreted as a product of pressure quenching of
pegmatite magma and attendant loss of volatiles. Zircon ages of rock
from atypical hornblende-bearing granodiorite from western part of older
dike is 121 Ma~id~ and 118.5 Ma~ip~. ^40^Ar/^39^Ar age of hornblende
117.7 Ma and biotite 118.8 Ma (Pb/U ages, W.R. Premo per. commun., 1999
and Ar ages, L. W. Snee, per. commun., 1999) Includes:

Kpvgr **Granophyre**---Pale gray, very fine-grained, porphyritic,
granophyre. Phenocrysts of altered plagioclase are in groundmass of
granophyric intergrowths of quartz within potassium feldspar and sodic
plagioclase. Pyrite is ubiquitous accessory mineral, and where oxidized,
discolors outcrops reddish-brown. Network of pegmatitic-textured
stringers averaging 2.5 cm thick cuts much of granophyre. Stringers are
compositionally and texturally zoned, with fine-grained margins and
coarse-grained interiors

Kpvp **Pegmatite dikes of Paloma Valley ring complex**---Linear to
arcuate, leucocratic pegmatite dikes typically 30 cm to 1 m thick. Most
are texturally and compositionally zoned. Outer zone is coarse-grained
granite composed of quartz perthite, and sodic plagioclase, and may or
may not contain biotite and minor magnetite. Inner zone consists of
pegmatitic-textured perthite, sodic plagioclase, quartz, biotite, and
(or) muscovite, and accessory magnetite, schorl, garnet, and epidote.
Quartz crystal-lined vugs found locally. Graphic intergrowths of quartz
and perthite are common in rock transitional between coarse-grained
granite and pegmatitic textured granite. Dikes that lack pegmatitic
cores consist entirely of coarse- to extremely coarse-grained granitoid
textured rock, with or without graphic intergrowths

Kpvg **Monzogranite to granodiorite**---Pale gray, massive,
medium-grained hypidiomorphic-granular biotite monzogranite, and less
abundant hornblende-biotite granodiorite forming older ring dike.
Plagioclase is An~20~ to An~35~, subhedral, tabular crystals. Contains
inclusions of small to large stoped blocks of gabbro

Kpvt **Tonalite**---Foliated biotite-hornblende tonalite. In eastern
part of complex grades into granodiorite

Kpvgb **Granodiorite and gabbro, undifferentiated**---Granodiorite of
Paloma Valley ring complex containing abundant masses of stoped
hornblende gabbro

Ksmg **Monzogranite of Squaw Mountain (Cretaceous)**---Informally named
here for exposures of monzogranite at Squaw Mountain (Wildomar 7.5'
quadrangle). Consists of massive, fairly homogeneous, moderately
leucocratic, coarse-grained, monzogranite. Weathers to form large
boulders of disintegration. Zircon age is 120 Ma~id~ and 123 Ma~ip~.
^40^Ar/^39^Ar age of hornblende is 111 Ma, biotite 111 Ma, and potassium
feldspar 103 Ma (Pb/U ages, W.R. Premo per. commun., 1999 and Ar ages,
L. W. Snee, per. commun., 1999)

Kts **Tonalite of Slaughterhouse Canyon (Cretaceous)**---Informally
named here for exposures of tonalite along Slaughterhouse Canyon
(Wildomar 7.5' quadrangle). Relatively fine-grained dark gray, massive
biotite hornblende tonalite. Sample of tonalite from near the head of
Slaughterhouse Canyon gave zircon age of 122 Ma~id~ and 125 Ma~ip~.
^40^Ar/^39^Ar age of hornblende is 120 Ma, biotite 111 Ma, and potassium
feldspar 103 Ma (Pb/U ages, W.R. Premo per. commun., 1999 and Ar ages,
L. W. Snee, per. commun., 1999)

#### Generic Cretaceous granitic rocks of the Peninsular Ranges batholith

Kp **Granitic pegmatite dikes (Cretaceous)**---Leucocratic, mostly
tabular, pegmatitic-textured granitic dikes. Most dikes range in
thickness from a few centimeters to over a meter. Larger dikes are
typically zoned compositionally and texturally, having a border and wall
zone consisting of coarse-grained biotite, quartz, and alkali feldspars.
Intermediate zone consists of large to giant crystals of quartz and
alkali feldspars, and commonly contain muscovite, schorl, and garnet.
Core zone consists of quartz and alkali feldspars. Line-rock layering is
rare. Pegmatite dikes within gabbro and metadunite may contain
andalusite, sillimanite, cordierite, and dumortierite. Where gabbro has
been incorporated into pegmatite it is converted to
vermiculite-hydrobiotite containing crystals of andalusite, some of
which have cores of corundum

Kg **Granitic dikes (Cretaceous)**---Includes texturally diverse group
of leucocratic granitic dikes composed mainly of quartz and alkali
feldspars. Dikes range in thickness from few centimeters to over a meter
and are up to several hundred meters in length. Most are tabular; some
are texturally and compositionally unzoned, irregular-shaped bodies.
Some dike rock has a foliated or gneissoid fabric. Textures are mostly
coarse grained and equigranular granitic but range from aplitic to
pegmatitic. Accessory minerals include biotite, muscovite, and garnet

Kgu **Granite, undifferentiated (Cretaceous)**---Leucocratic fine- to
coarse-grained massive granite and biotite monzogranite. Most is
equigranular and consists of quartz and alkali feldspars. In leucocratic
granite, biotite is a widespread varietal mineral. Muscovite-bearing
granite occurs at Bell Mountain (Romoland 7.5' quadrangle)

Kmgt **Monzogranite and tonalite, undifferentiated
(Cretaceous)**---Undifferentiated biotite monzogranite and
biotite-hornblende tonalite. Restricted to single occurrence in the
eastern part of the Box Springs Mountains (Sunnymead 7.5' quadrangle)

Kgd **Granodiorite, undifferentiated (Cretaceous)**---Biotite and
hornblende-biotite granodiorite, undifferentiated. Most is massive and
medium grained

Kt **Tonalite, undifferentiated (Cretaceous)**---Gray, medium-grained
biotite-hornblende tonalite, typically foliated

Ktm **Tonalite and mafic rock, undifferentiated
(Cretaceous)**---Subequal amounts of foliated, gray, medium grained
biotite-hornblende tonalite and meso- to melanocratic inclusion-like
rock, which gives rise to migmatitic appearing rock

Kqd **Quartz diorite (Cretaceous)**---Medium- to coarse-grained
biotite-hornblende quartz diorite. Most is slightly to well foliated
with discoidal to pancake-shaped melanocratic inclusions in foliation
plane. Grades into diorite and biotite-hornblende tonalite

Kdqd **Diorite and quartz diorite, undifferentiated
(Cretaceous)**---Dark gray, medium- to coarse-grained mixtures of
hornblende diorite and biotite and biotite-hornblende quartz diorite

Kd **Diorite, undifferentiated (Cretaceous)**---Mostly fine- to
medium-grained, massive, dark gray to black hornblende diorite

Kgb **Gabbro (Cretaceous)**---Mainly hornblende gabbro. Includes
Virginia quartz-norite and gabbro of Dudley (1935), and San Marcos
gabbro of Larsen (1948). Typically brown-weathering, medium- to very
coarse-grained hornblende gabbro; very large poikilitic hornblende
crystals are common, and very locally gabbro is pegmatitic. Much is
quite heterogeneous in composition and texture. Includes noritic and
dioritic composition rocks

Khg **Heterogeneous granitic rocks (Cretaceous)**---A wide variety of
heterogeneous granitic rocks occur in Santa Ana quadrangle. Some
heterogeneous assemblages include large proportions of schist and
gneiss. Rocks in Santa Ana Mountains include a mixture of monzogranite,
granodiorite, tonalite, and gabbro. Tonalite composition rock is most
abundant rock type. Tonalite from Hot Springs Canyon (Cañada Gobernadora
7.5' quadrangle), gave zircon age of 119.2 Ma~id~ and 116.5 Ma~ip~ (Pb/U
ages, W.R Premo per. commun., 1999). Heterogeneous granitic rocks
adjacent to east and south of Lakeview Mountains and Reinhardt Canyon
pluton contain large amount of metamorphic rock. Except for southern
part, granitic component consists of potassium feldspar-bearing tonalite
and granodiorite

#### End granitic rocks of the Peninsular Ranges batholith

Ks **Serpentinite (Cretaceous)**---Small body of highly deformed,
slickensided, greenish-brown serpentine within Santiago Peak volcanics
(Corona South 7.5' quadrangle)

Kc **Carbonate-silicate rock (Cretaceous)**---Small body of
reddish-brown carbonate-silicate rock spatially associated with
serpentinite (Ks)

Kvsp **Santiago Peak Volcanics (Cretaceous)**---Basaltic andesite,
andesite, dacite, rhyolite, volcaniclastic breccia, welded tuff, and
epiclastic rocks (Herzig, 1991); widespread in the northern Santa Ana
Mountains. Originally named Black Mountain volcanics by Hanna (1926),
but name was pre-empted. Larsen (1948) renamed unit Santiago Peak
Volcanics for exposures in vicinity of Santiago Peak, northern Santa Ana
Mountains. Rocks are very heterogeneous, discontinuous, and poorly
exposed. Most of unit is hydrothermally altered; alteration was
contemporaneous with volcanism. Zircon ages of Santiago Peak Volcanics
range from 123 to 134 Ma (Anderson, 1991), making it coeval with older
part of Peninsular Ranges batholith

Kvspi **Intrusive rocks associated with Santiago Peak Volcanics
(Cretaceous)**---Shallow porphyritic intrusive rocks principally of
intermediate composition. Composed of plagioclase, clinopyroxene and
altered orthopyroxene. Silicic porphyries composed of plagioclase,
quartz, and altered pyroxene and biotite (Herzig, 1991)

Kvem **Estelle Mountain volcanics of Herzig (1991)
(Cretaceous)**---Heterogeneous mixture of rhyolite flows, shallow
intrusive rocks, and volcaniclastic rocks (Corona South, Lake Mathews,
Alberhill and Elsinore 7.5' quadrangles); andesite is rare. Informally
named by Herzig (1991) for exposures in vicinity of Estelle Mountain
(Lake Mathews 7.5' quadrangle). These rocks were termed Temescal
dacite-porphyry by Dudley (1935) and Temescal Wash quartz latite
porphyry by Larsen (1948). Zircon age of rock from unit collected west
of Lake Mathews (Lake Mathews 7.5' quadrangle), is 125.8 Ma (Anderson,
1991)

Kvr **Rhyolite of Estelle Mountains volcanics of Herzig (1991)
(Cretaceous)**---Rhyolite; relatively uniform and homogeneous

Ksv **Intermixed Estelle Mountain volcanics of Herzig (1991) and
Cretaceous(?) sedimentary rocks (Cretaceous?)**---Complexly intermixed
volcanic and sedimentary rocks, which appear to be coeval; sedimentary
rocks predominate

Kvs **Intermixed Estelle Mountain volcanics of Herzig (1991) and
Mesozoic sedimentary rocks (Mesozoic)**---Complexly intermixed volcanic
and sedimentary rocks; volcanic rocks predominate. West of Lake Mathews
much of sedimentary rock predates volcanic rocks. In Elsinore 7.5'
quadrangle, much of sedimentary rock appears coeval with volcanics

**Deformed granitic rocks of Transverse Ranges Province
(Mesozoic)**---Assemblage of deformed Mesozoic granitic rocks that are
part of an assemblage characteristic of upper plate rocks of Vincent
Thrust in Transverse Ranges Province. Restricted to northeast corner of
El Casco 7.5' quadrangle. Includes:

}mg **Mylonitic and cataclastic granitic rocks**---Fine- to
coarse-grained cataclastic granodiorite, tonalite, and quartz diorite.
Has non-penetrative and penetrative fabrics, including sheared and
crushed rock, brittle cataclastic fabrics, and ductile mylonitic fabrics
(northeast corner of the El Casco 7.5' quadrangle)

}dy **Diorite, Yucaipa area**---Medium- to coarse-grained, massive to
incipiently foliated hornblende-biotite diorite and quartz diorite
(northeast corner of the El Casco 7.5' quadrangle)

Jbc **Bedford Canyon Formation (Jurassic)**---Slightly metamorphosed
assemblage of interlayered argillite, slate, graywacke, impure
quartzite, and small masses of limestone. As used here, Bedford Canyon
Formation is areally limited to northern part of Santa Ana Mountains.
Most of unit is poorly exposed, best exposures restricted to road cuts.
Bedding and primary sedimentary structures are commonly preserved,
although tightly folded bedding is common. Fissile, black argillite and
slate are very fine grained and consist of beds 2 to 8 cm in thickness.
Massive bedded, impure, fine- to medium-grained, pale gray to pale brown
quartzite and graywacke beds are 4 to 30 cm thick. Locally carbonaceous.
Lenses of conglomerate occur sparsely through sequence. Incipiently
developed transposed layering, S~1~, is locally well-developed.
Includes:

Jbc~1~ **Bedford Canyon Formation, Unit 1**---The southern part of the
unit consists of brown-weathering, massive-appearing quartz-rich
metasandstone and impure quartzite. Locally some thin-layered
fine-grained sandy intervals with discontinuous small folds (6-8cm).
Locally contains abundant fine-grained dissiminated pyrite

Jbm **Marble and limestone**---Small elongate to equant-shaped bodies of
gray weathering, fine-grained marble (limestone), some fossiliferous.
Ammonites occur at a few places (Imlay, 1963, 1964, and 1980;
Silberling, and others, 1961), and rhynchonelloid brachiopod debris is
locally abundant (Gray, 1961)

}u **Mesozoic metasedimentary rocks, undifferentiated
(Mesozoic)**---Wide variety of low- to high-metamorphic grade
metamorphic rocks. Most occurrences include biotite schist

}g **Graywacke (Mesozoic)**---Predominately lithic graywacke (Romoland
and Winchester 7.5' quadrangles). Thick layered, massive, commonly
contains angular fragments of phyllite (chips) and discontinuous layers
of phyllite in low metamorphic grade rocks or biotite schist is higher
grade rocks

}q **Quartz-rich rocks (Mesozoic)**---Quartzite and quartz-rich
metasandstone (Elsinore and Romoland 7.5' quadrangles)

}qg **Intermixed quartzite and graywacke (Mesozoic)**---Intermixed
quartzite and lithic metagraywacke; quartzite may or may not be
feldspathic (Romoland and Winchester 7.5' quadrangles)

}gp **Intermixed graywacke and phyllite (Mesozoic)**---Intermixed lithic
metagraywacke and phyllite. Other metasedimentary rocks may be present
in small amounts (Romoland and Winchester 7.5' quadrangles)

}p **Phyllite (Mesozoic)**---Fissile black phyllite. Occurs in thick
sections in the Romoland and Elsinore 7.5' quadrangles. Commonly with
sheen produced by very fine-grained white mica on s-surface; locally
contains small elongate prisms of fine-grained white mica, which maybe
pseudomorphs after chiastolite

}s **Schist (Mesozoic)**---Biotite schist, in part gradational with
phyllite (Winchester and Bachelor Mountains 7.5' quadrangles). In lower
metamorphic-grade rocks, consists of andalusite-biotite schist. In
higher metamorphic-grade rocks, includes cordierite biotite schist, and
in highest metamorphic-grade rocks sillimanite schist, and less commonly
garnet bearing schist

}m **Marble (Mesozoic)**---Pod-like masses and elongate layers of marble
and calcsilicate rocks. Occurrences in low metamorphic-grade rocks
(e.g., phyllite association) are relatively fine-grained, off-white to
gray marble. Commonly contains masses of radiating blades of white
tremolite. Small mass of fine-grained dark gray to black marble and
calcsilicate rock in hills east of Sun City contains deformed and poorly
preserved pelycepods and crinoids

}i **Interlayered phyllite (or schist) and quartzite
(Mesozoic)**---Western part of unit is low metamorphic-grade,
interlayered, relatively pure quartzite and phyllite. Eastern part of
unit is higher metamorphic-grade quartzite and biotite schist. In
western low metamorphic-grade part of unit, some quartzite layers in
hinges of slip folds are 8 to 24 cm thick, and may be relic beds (S~0~)
preserved in hinges. In this area, however, there are also transposed
quartzite layers (S~1~) in limbs of folds that are 5 to 7 cm thick. In
areas of intermediate metamorphic-grade, quartzite layers are
retransposed (S~2~) and further attenuated to thickness of 1 to 2.5 cm.
In easternmost part of unit they are transposed again (S~3~) to
thickness of about 6 mm (Romoland and Winchester 7.5' quadrangles)

}mn **Manganese-bearing rocks (Mesozoic)**---Layers of black
manganese-bearing quartz-rich metasediments. Consists of manganese
oxides-hydroxides and rhodonite in quartzite. Widespread minor
occurrences in Railroad Canyon area (Elsinore and Winchester 7.5'
quadrangles). Has been prospected as source of manganese (Sampson, 1935)

}a **Amphibolite (Mesozoic)**---Black elongate-shaped masses of
plagioclase and hornblende mainly within }gn. Locally contains garnet in
vugs

}sgn **Mixed low metamorphic grade and upper amphibolite grade rocks
(Mesozoic)** ---Tectonically intermixed schist, graywacke, and impure
quartzite of }s, }g, }q, and }gn (Winchester 7.5' quadrangle). Includes
known occurrences of metaserpentine-metadunite and related rocks (}ds,
}dx, and }dc) which are restricted to this unit. Note: In Version 1 of
this map this unit was included in }s. Based on reexamination, the
eastern part of }s is now interpreted as a broad suture zone consisting
of a mixture of rocks from both to the west and to the east and includes
metaserpentinite and related rocks that appear to be unique to this
mixed unit. Included is:

}ds **Metadunite and serpentinite**---Assemblage of metadunite, in large
part serpentinized, and related metamorphic rocks. Forms several large
masses on ridge between Diamond Valley and San Jacinto Valley, locally
known as Searl Ridge. Least altered metadunite is composed essentially
of olivine and talc. At and near outer margins of some metadunite is a
layer consisting of essentially enstatite, and in some places an outer
thin (few centimeters) of spinel-rich rock. Surrounding metadunite is
selvage 0.5 to 6 m thick of massive rock containing large proportion of
2 to 5 cm poikiloblastic cordierite in sillimanite-biotite rock.
Cordierite apparently formed from magnesium in dunite during
metamorphism. Granitic pegmatite dikes intruding metadunite have outer
parts containing andalusite, sillimanite, dumortierite, and cordierite.
Metadunite adjacent to pegmatite is altered to an inner layer of
hydrobiotite and vermiculite; and an outer layer of chlorite and
amphibole. Thoroughly serpentinized metadunite (}sm) contains veinlets
of magnesite, which was formerly mined

}dx **Amphibole- and pyroxene-bearing rocks associated with
metadunite-serpentinite**---Includes wide variety of amphibole and
pyroxene bearing rocks spatially associated with dunite. Ranges from
white to green to black amphibolite and pyroxenite and pink
anthophylite. Includes some carbonate rock and metasomatized schist.
Isolated small exposures of these rocks are found in the vicinity of
metadunite and serpentinite (}ds) occurrences at Double Butte and Searl
Ridge in the vicinity of Rawson Valley

}dc **Marble associated with metadunite**---Coarse-grained impure marble
adjacent to metadunite. Marble consists of calcite and variable amounts
of olivine, pyroxene, amphibole, spinel, and opaque minerals. Some
silicate minerals are concentrated in layers. Marble apparently is
metamorphosed silica-carbonate rock associated with serpentinite

}gn **Biotite gneiss and schist (Mesozoic)**---Medium- to dark-gray,
coarse-grained biotite gneiss and schist, and biotite-quartz-feldspar
gneiss and schist (Winchester 7.5' quadrangle). Locally contains
sillimanite and cordierite. Commonly includes minor amounts of quartzite
and calc-silicate hornfels. Anatectic stringers of granitic material are
common. Note: This unit was referred to as Paleozoic? in Version 1 of
this quadrangle; subsequent isotopic study of zircons found relic
zircons of Mesozoic age (Premo, and others, 2002)

Kg} **Intermixed Mesozoic schist and Cretaceous granitic rocks
(Mesozoic)**---Wide variety of Mesozoic schist and related metamorphic
rocks mixed with granitic rocks ranging in composition from monzogranite
to quartz diorite. Most granitic rocks are tonalite composition

Kg\| **Intermixed Paleozoic(?) schist and Cretaceous granitic rocks
(Mesozoic and Paleozoic?)**---Varied Paleozoic(?) schist and gneiss
intermixed with granitic rocks. Most granitic rocks are tonalite
composition

\|u **Paleozoic(?) rocks, undifferentiated (Paleozoic?)**---Includes
wide variety of metamorphic rocks, most are of sedimentary protolith (El
Casco, Lakeview, Riverside East and Riverside West 7.5' quadrangles).
Mainly intercalated biotite schist and quartzite, gneiss, and lesser
amounts of quartzite, hornblende gneiss, marble and associated skarn and
calc-silicate rock. Sillimanite is common in biotite schist and garnet
less common. Marble layers (m) within \|u include coarse- and very
coarse-grained white and gray marble occurring as pods and layers within
biotite schist and gneiss. Most marble is in contact with or is near
granitic rocks; pyroxene hornfels metamorphic mineral assemblages are
common. Marble contains small amounts of diopside, forsterite,
wollastonite, spinel, and graphite. Mineralogy of spatially associated
skarns includes wollastonite, idocrase and garnet

\|s **Biotite schist (Paleozoic?)**---Medium- to dark-gray, fine-grained
biotite schist and biotite-quartz-feldspar schist. Locally contains
sillimanite and cordierite. Commonly includes minor amounts of quartzite
and calc-silicate hornfels

\|q **Impure quartzite (Paleozoic?)**---Light-gray to
light-greenish-gray, fine- to medium-grained, layered to massive, impure
quartzite. Locally consists of intensely slip-folded quartzite
interlayered with wollastonite rock. Weathers reddish-brown or
orangish-brown

\|m **Marble (Paleozoic?)**---White to light gray, locally bluish-gray,
and pale to medium blue, coarse- to extremely coarse-grained marble.
Locally includes calc-silicate hornfels, quartzite, biotite schist, and
skarn. Most of the skarn occurs along the contact between marble and
tonalite. Where in contact with tonalite marble, has mineral assemblages
of pyroxene hornfels facies. Contact zones contain a wide variety of
minerals, some uncommon or rare. Marble at New City Quarry (Victoria Ave
Quarry) in Riverside, for example, contains borate-bearing skarn,
ludwigite-pageite-vonsenite, associated with magnetite. Larger marble
bodies which have been mined for various purposes

\|c **Calc-silicate rocks (Paleozoic?)**---Heterogeneous, massive to
well-layered calc-silicate rocks accompanied by variable amounts of
marble, quartzite, and biotite schist

\|ms **Marble and schist, undivided (Paleozoic?)**---Heterogeneous
mixture of marble and biotite schist; massive to foliated

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Premo, W.R., Morton, D.M., Snee, L.W., Naeser, N.D., and Fanning, C.M.,
1998, Isotopic ages, cooling histories, and magmatic origins for
Mesozoic tonalite plutons from the northern Peninsular Ranges batholith,
southern California: Geol. Soc. Amer. Abstracts with programs, v. 30, n.
5, p. 59.

Proctor, R.J., 1962, Geologic features of a section across the Casa Loma
fault, exposed in an aqueduct trench near San Jacinto, California: Geol.
Soc. America Bull., v. 73, p. 1293-1296.

Proctor, R.J., and Downs, Theodore, 1963, Stratigraphy of a new
formation containing early Pliocene vertebrates at Lake Mathews, near
Riverside, California: Geol. Soc. America, Abs. for 1962, Spec. Paper
73, p. 59.

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

Reynolds, R.E., Fay, L.P., and Reynolds, R.L., 1990, An early-late
Irvingtonian land mammal age fauna from Murrieta, Riverside County,
California: San Bernardino County Museum Association Quarterly, v.
XXXVII, p. 35-36.

Reynolds, R.E., and Reynolds, R.L., 1990a, A new late Blancan faunal
assemblage from Murrieta, Riverside County, California: San Bernardino
County Museum Association Quarterly, v. XXXVII, p. 34.

\_\_\_\_\_\_\_, 1990b, Irvingtonian? Faunas from the Pauba Formation,
Temecula, Riverside County, California: San Bernardino County Museum
Association Quarterly, v. XXXVII, p. 37.

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

Sampson, R.J, 1935, Mineral resources of a portion of the Perris block,
Riverside County, California: California Journal of Mines and Geology,
v. 31, p. 507-521.

Schoellhamer, J.E., Kinney, D.M., Yerkes, R.F., and Vedder, J.G., 1954,
Geologic map of the northern Santa Ana Mountains, Orange and Riverside
Counties, California: U.S. Geol. Survey Oil and Gas investigations Map
OM 154 (scale 1:24,000).

Schoellhamer, J.E., Vedder, J.G, Yerkes, R.F., and Kinney, D.M., 1981,
Geology of the northern Santa Ana Mountains, California: U.S. Geol.
Survey Prof. Paper 420-D, 109 p.

Schwarcz, H.P., 1969, Pre-Cretaceous sedimentation and metamorphism in
the Winchester area, northern Peninsular Ranges, California: Geol. Soc.
Amer. Special Paper 100, 63 p.

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

Shelton, J.S., 1955, Glendora volcanic rocks, Los Angeles Basin,
California: Geol. Soc. Amer. Bull., v. 66, n. 1, p. 45-89.

Silberling, N.J., Schoellhamer, J.E., Gray, C.H., and Imlay, R.W., 1961,
Upper Jurassic fossils from Bedford Canyon Formation, southern
California: Amer. Assoc. Petroleum Geologists Bull., v. 45, n. 10, p.
1746-1748.

Silver, L.T., and Chappel, B.W., 1988, The Peninsular Ranges batholith:
An insight into the evolution of the Cordilleran batholiths of
southwestern Northern America: Trans. Royal Soc. of Edinburgh, Earth
Sciences, v. 79, p. 105-121.

Smith, D.K., Morton, D.M., and Miller, F.K., 1991, Hornblende
geobarometry and biotite K-Ar ages from the northern part of the
Peninsular Ranges batholith, southern California: Geol. Soc. Amer. Abst.
with Programs, v. 23, p. 273.

Smith, J.P., 1898, Geographic relations of the Trias of California:
Jour. Geology, vol. 6, p. 776-786.

\_\_\_\_\_, 1914, The middle Triassic marine invertebrate faunas of
North America: U.S. Geol. Prof. Paper 83, 145 p.

Smith, P.B., 1960, Foraminifera of the Monterey Shale and Puente
Formation, Santa Ana Mountains and the San Juan Capistrano area,
California: U.S. Geol. Survey Prof. Paper 254-M, p. 463-495.

Stewart, R.E., and Stewart, K.C., 1930, "Lower Pliocene" in the eastern
end of the Puente Hills, San Bernardino County, California: Am. Assoc.
Petroleum Geologists Bull., v. 14, p. 1445-1450.

Todd, V.R., Erskine, B.G., and Morton, D.M., 1988, Metamorphic and
tectonic evolution of the northern Peninsular Ranges batholith, southern
California: Ruby vol. VII, p. 894-937.

Vedder, J.G., 1957, New stratigraphic names used on geologic map of the
San Joaquin Hills-San Juan Capistrano area, Orange County, California
*in* Vedder, J.G., Yerkes, R.F., and Schoellhamer, J.E., Geologic map of
the San Joaquin Hills-San Juan Capistrano area, Orange County,
California: U.S. Geol. Survey Oil and Gas Inv. Map OM-193.

\_\_\_\_\_\_, 1960, Previously unreported Pliocene Mollusca from the
southeastern Los Angeles basin: U.S. Geol. Survey Prof. Paper 400-B, p.
B326-B328.

\_\_\_\_\_\_, 1972, Review of stratigraphic names and megafaunal
correlations of Pliocene rocks along the southeast margin of the Los
Angeles basin, California, *in* Stinemeyer, E.H., ed., Pacific Coast
Miocene Biostratigraphic Symposium: Soc. Econ. Paleontologists and
Mineralogists, Pacific Sec., Bakersfield, Calif., March, 1972, p.
158-172.

\_\_\_\_\_\_, 1975, Revised geologic map, structure sections, and well
tables, San Joaquin Hills-Capistrano area, California: U.S. Geol. Survey
Open-file Rept. 75-552.

Vedder, J.G., Yerkes, R.F., and Schoellhamer, J.E., 1957, Geologic map
of the San Joaquin Hills-San Juan Capistrano area, Orange County,
California: U.S. Geological Survey Oil and Gas Inv. Map OM-193.

Watts, W.L., 1897, Oil and gas yielding formation of Los Angeles,
Ventura, and Santa Barbara Counties, California: Calif. Mining Bur.,
Bull. 11, 72 p.

Webb, R.W., 1939, Evidence of the age of a crystalline limestone,
southern California: Jour. Geol., v. 47, p. 198-201.

Weber, F.H. Jr, 1976, Preliminary map of faults of the Elsinore and
Chino fault zones in northeastern Riverside County, California, showing
accompanying features related to character and recency of movement:
California Div. Mines and Geology Open-file Report 76-1 LA.

White, W.R., 1956, Pliocene and Miocene Foraminifera from the Capistrano
Formation, Orange County, California: Jour. Paleontology, v. 30, p.
237-270.

\_\_\_\_\_, 1971, Biostratigraphy of the Capistrano Formation, Dana
Point, California, in Berger, F.W., ed., Geological guide book Newport
Lagoon to San Clemente, Orange County, California: Soc. Econ.
Paleontologists and Mineralogists, Pacific Section, p. 50-54.

Whitney, J.D., 1865, Geological Survey of California, Geology, v. 1,
Report of progress and synopsis of field work from 1869-1864, 498 p.

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

Woodford, A.O., 1924, The Catalina Metamorphic Facies of the Franciscan
series: University of California Pub. Geol. Sciences, v. 15, n. 3, p.
49-68.

\_\_\_\_\_\_\_, 1925, The San Onofre breccia: Its nature and origin:
California Univ. Pubs., Dept. Geol. Sci. Bull., v 15, no. 7, p. 159-280.

Woodford, A.O., McCulloh, T.H., and Schoellhamer, J.E., 1973,
Paleographic significance of metatuff boulders in middle Tertiary
strata, Santa Ana Mountains, California: Geol. Soc. America Bull. v. 83,
no. 11, p. 3433-3436.

Woodford, A.O., Moran, T.G., and Shelton, J.S., 1946, Miocene
conglomerates of Puente and San Jose Hills, California: Am. Assoc.
Petroleum Geologists Bull., v. 30, p. 514-560.

Woodford, A.O., Shelton, J.S., and Moran, T.G., 1944, Geology and oil
possibilities of Puente and San Jose Hills, California: U.S. Geol.
Survey Oil and Gas Inv. Prelim. Map 23.

Woodford, A.O, Shelton, J.S., Doehring, D.O., and Morton, R.K., 1971,
Pliocene-Pleistocene history of the Perris Block, southern California:
Geol. Soc. America Bull., v. 82, no. 12, p. 3421-3448.

Woodford, A.O., Welday, E.E., and Merriam, Richard, 1968, Siliceous tuff
clasts in the upper Paleogene of southern California: Geol. Soc. America
Bull., v. 79, p. 1461-1486.

Woodring, W.P., 1938, Lower Pliocene mollusks and echinoids from the Los
Angeles basin, California, and their inferred environment: U.S.
Geological Survey Prof. Paper 190, 67 p.

Woodring, W.P., and Popenoe, W.P., 1942, Upper Cretaceous formations and
faunas of southern California: Amer. Assoc. Petroleum Geologists
Bulletin, vol. 26, no. 2, p. 166-176.

\_\_\_\_\_\_\_, 1945, Paleocene and Eocene stratigraphy of northwestern
Santa Ana Mountains, Orange County, California: U.S. Geol. Survey Oil
and Gas investigations Prelim. Chart OC 12.

Yerkes, R.F., 1957, Volcanic rocks of the El Modeno area, Orange County,
California: U.S. Geol. Survey Prof. Paper 247-L, p. 313-334.

\_\_\_\_\_\_, 1972, Geology and oil resources of the western Puente
Hills area, southern California: U.S. Geol. Survey Prof. Paper 420-C, 63
p.

Yerkes, R.F., McCulloh, T.H., Schoellhamer, J.E., and Vedder, J.G.,
1965, Geology of the Los Angeles basin, California \-- An introduction:
U.S. Geol. Survey Prof. Paper 420-A, 57 p.

Yerkes, R.F., and Campbell, R.H., 1979, Stratigraphic nomenclature of
the central Santa Monica Mountains, Los Angeles County, California: U.S.
Geol. Survey Bulletin 1457-E, 31 p.

**Sources of mapping used in the Santa Ana 30\' x 60\' quadrangle listed
by 7.5' quadrangle**

# Alberhill

Greenwood, R.B., 1992, Geologic map of the Alberhill 7.5' quadrangle:
California Division of Mines and Geology Open-file Report 92-10; Weber,
F.H. Jr, 1976, Preliminary map of faults of the Elsinore and Chino fault
zones in northeastern Riverside County, California, showing accompanying
features related to character and recency of movement: California Div.
Mines and Geology Open-file Report 76-1; Morton, D.M., unpublished
mapping, 1996.

# Anaheim 

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Eckmann, E.C., Strahorn, A.T., Holmes,
L.C., and Guernsey, J.E., 1919, Soil survey of the Anaheim area,
California: U.S. Dept. of Agriculture, Advance Sheets -- Field
Operations of the Bureau of Soils, 1916, 79 p.; Vedder, J.G.,1975,
Revised geologic map, structure sections, and well tables, San Joaquin
Hills-Capistrano area, California: U.S. Geol. Survey Open-file Rept.
75-552.

# Bachelor Mountain

Morton, D.M., and Kennedy, M.P., 2003, Geologic map of the Bachelor
Mountain 7.5\' Quadrangle, Riverside County, California.
<http://geopubs.wr.usgs.gov/open-file/of03-103>

# Black Star Canyon

Schoellhamer, J.E., Vedder, J.G., Yerkes, R.F., and Kinney, D.M., 1981,
Geology of the northern Santa Ana Mountains, California: U.S. Geological
Survey Prof. Paper 420-D, 109 p.; Morton, P.K., and Miller, R.V., 1981,
Geologic map of Orange County, California showing mines and mineral
deposits: California Division of Mines and Geology Bull. 204; Tan, S.S.
1990, Landslide hazards in the northern half of the Black Star Canyon
quadrangle, Orange County, California: California Division of Mines and
Geology Open-File Report 90-19; Morton, D.M., unpublished mapping, 1996.

# Cañada Gobernadora

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Morton, D.M., unpublished mapping, 1996;
Tan, S.S., undated, unpublished mapping.

# Corona North

Morton, D.M., and Gray, C.H., Jr., 2002, Geologic map of the Corona
North 7.5' Quadrangle, Riverside and San Bernardino Counties,
California. http://geopubs.wr.usgs.gov/open-file/of02-022

# 

# Corona South

Gray, C.H., Jr., Morton, D.M., and Weber, F.H., Jr., 2002, Geologic map
of the Corona South 7.5' Quadrangle, Riverside and Orange Counties,
California. http://geopubs.wr.usgs.gov/open-file/of02-021

# El Casco

# Matti, J.C., unpublished mapping, 1973-4, 1996-7, 2003; Morton, D.M., unpublished mapping 1995-7

# Elsinore

Morton, D.M., and Weber F.H., Jr., 2003, Geologic map of the Elsinore
7.5' Quadrangle, Riverside County, California.
<http://geopubs.wr.usgs.gov/open-file/of03-281>

# El Toro

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Eckmann, E.C., Strahorn, A.T., Holmes,
L.C., and Guernsey, J.E., 1919, Soil survey of the Anaheim area,
California: U.S. Dept. of Agriculture, Advance Sheets -- Field
Operations of the Bureau of Soils, 1916, 79 p.; Tan, S.S., Miller, R.V.,
and Fife, D.L., 1984, Geology of the north half of the El Toro
quadrangle, Orange County, California: California Division of Mines and
Geology Open-File Report 84-28.

# Laguna Beach

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Vedder, J.G., 1975, Revised geologic map,
structure sections, and well tables, San Joaquin Hills-Capistrano area,
California: U.S. Geol. Survey Open-file Rept. 75-552; Tan, S.S., and
Edgington, W.J., 1976, Geology and engineering geologic aspects of the
Laguna Beach quadrangle, Orange County, California: California Division
of Mines and Geology Special Report 127; Kern, J.P., 1996, Geological
mapping of marine terraces and marine terrace deposits in coastal
southern California: California Division of Mines and Geology
unpublished reports, Interagency Agreement 1094-046.; Tan, S.S.,
undated, unpublished mapping.

# La Habra

Yerkes, R.F., 1972, Geology and oil resources of the western Puente
Hills area, southern California: U.S. Geological Survey Prof. Paper
420-C, 63 p.; Tan, S.S., 1988, Landslide hazards in the Puente and San
Jose Hills, southern California: California Division of Mines and
Geology Landslide Identification Map no. 12B-SE, 12B-W, Open-file Report
88-21.; Tan, S.S., and Evans, J.R., 1984, Geology of the south half of
the La Habra quadrangle, Orange County, California : California Division
of Mines and Geology Open-File Report 84-24.

# Lake Mathews 

Morton, D.M., and Weber F.H., Jr., 2001, Geologic map of the Lake
Mathews 7.5' Quadrangle, Riverside County, California.
http://geopubs.wr.usgs.gov/open-file/of01-479

# Lakeview

Morton, D.M., and Matti, J.C., 2001, Geologic map of the Lakeview 7.5\'
Quadrangle, Riverside County, California.
<http://geopubs.wr.usgs.gov/open-file/of01-174>

# Murrieta

Kennedy, M.P., and Morton, D.M., 2003, Preliminary Geologic map of the
Murrieta 7.5\' Quadrangle, Riverside County, California.
[http://geopubs.wr.usgs.gov/open-file/of03-189](http://geopubs.wr.usgs.gov/open-file/of03-188)

# Newport Beach

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204.; Vedder, 1975; Eckmann, E.C., Strahorn,
A.T., Holmes, L.C., and Guernsey, J.E., 1919, Soil survey of the Anaheim
area, California: U.S. Dept. of Agriculture, Advance Sheets -- Field
Operations of the Bureau of Soils, 1916, 79 p.; Kern, J.P., 1996,
Geological mapping of marine terraces and marine terrace deposits in
coastal southern California: California Division of Mines and Geology
unpublished reports, Interagency Agreement 1094-046.; Tan, S.S.,
undated, unpublished mapping.

# Orange

Tan, S.S., 1995, Landslide hazards in the Orange quadrangle, Orange
County, California: California Division of Mines and Geology Landslide
Identification Map no. 34, Open-file Report 95-11; Eckmann, E.C.,
Strahorn, A.T., Holmes, L.C., and Guernsey, J.E., 1919, Soil survey of
the Anaheim area, California: U.S. Dept. of Agriculture, Advance Sheets
-- Field Operations of the Bureau of Soils, 1916, 79 p.

# Perris

Morton, D.M., 2003, Geologic map of the Perris 7.5' Quadrangle,
Riverside County, California.
http://geopubs.wr.usgs.gov/open-file/of03-270

# Prado Dam 

Durham, D.L., and Yerkes, R.F., 1964, Geology and oil resources of the
eastern Puente Hills, southern California: U.S. Geological Survey Prof.
Paper 420-B, 62 p.; Tan, S.S., 1988, Landslide hazards in the Puente and
San Jose Hills, southern California: California Division of Mines and
Geology Landslide Identification Map no. 12B-SE, 12B-W, Open-file Report
88-21; McCulloh, T.H., unpublished mapping, 1996,2000; Morton, D.M.,
unpublished mapping, 1997

# Riverside East

Morton, D.M., and Cox, B.F., 2001, Geologic map of the Riverside East
7.5' Quadrangle, Riverside County, California.
http://geopubs.wr.usgs.gov/open-file/of01-452

# Riverside West

Morton, D.M., and Cox, B.F., 2001, Geologic map of the Riverside West
7.5' Quadrangle, Riverside County, California.
http://geopubs.wr.usgs.gov/open-file/of01-451

# Romoland

Morton, D.M., 2003, Geologic map of the Romoland 7.5\' Quadrangle,
Riverside County, California.
<http://geopubs.wr.usgs.gov/open-file/of03-102>

# San Juan Capistrano

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Vedder, J.G., 1975, Revised geologic map,
structure sections, and well tables, San Joaquin Hills-Capistrano area,
California: U.S. Geol. Survey Open-file Rept. 75-552; Tan, S.S.,
undated, unpublished mapping

# Santiago Peak

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Morton, D.M., unpublished mapping, 1997;
Tan, S.S., undated, unpublished mapping

# Sitton Peak

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204; Alvarez, R.M. and Morton, D.M., unpublished
mapping, 1996, 2003.

# Steele Peak

Morton, D.M., 2001, Geologic map of the Steele Peak 7.5' Quadrangle,
Riverside County, California.
http://geopubs.wr.usgs.gov/open-file/of01-449

# Sunnymead

Morton, D.M., and Matti, J.C.. 2001, Geologic map of the Sunnymead 7.5'
Quadrangle, Riverside County, California.
http://geopubs.wr.usgs.gov/open-file/of01-450

# Tustin

Morton, P.K., and Miller, R.V., 1981, Geologic map of Orange County,
California showing mines and mineral deposits: California Division of
Mines and Geology Bull. 204.; Eckmann, E.C., Strahorn, A.T., Holmes,
L.C., and Guernsey, J.E., 1919, Soil survey of the Anaheim area,
California: U.S. Dept. of Agriculture, Advance Sheets -- Field
Operations of the Bureau of Soils, 1916, 79 p.; Vedder, J.G., 1975,
Revised geologic map, structure sections, and well tables, San Joaquin
Hills-Capistrano area, California: U.S. Geol. Survey Open-file Rept.
75-552; Tan, S.S., undated, unpublished mapping.

# Wildomar

Kennedy, M.P., 1977, Recency and character of faulting along the
Elsinore fault zone in southern Riverside County, California: California
Div. Mines and Geology, Special Report 131, 12 p.; Alvarez, R.M., and
Morton, D.M., unpublished mapping, 1996

# Winchester

Morton, D.M., 2003, Preliminary Geologic map of the Winchester 7.5\'
Quadrangle, Riverside County, California.
<http://geopubs.wr.usgs.gov/open-file/of03-188>

# Yorba Linda

Yerkes, R.F., 1972, Geology and oil resources of the western Puente
Hills area, southern California: U.S. Geological Survey Prof. Paper
420-C, 63 p.; Tan, S.S., 1988, Landslide hazards in the Puente and San
Jose Hills, southern California: California Division of Mines and
Geology Landslide Identification Map no. 12B-SE, 12B-W, Open-file Report
88-21; Tan, S.S., and Miller, R.V., 1984, Geology of the south half of
the Yorba Linda quadrangle, Orange County, California: California
Division of Mines and Geology Open-File Report 84-24.

**DIGITAL PREPARATION OF INDIVIDUAL 7.5' QUADRANGLES**

# Alberhill

Melinda C. Wright, Diane Burns

## Anaheim

Rachel M. Alvarez

## Bachelor Mountain

Kelly R. Bovard, Diane Burns

## Black Star Canyon

Kelly R. Bovard, Gary W. Patt, Katherine Koukladas

**Cañada Gobernadora**

Rachel M. Alvarez, Kelly R. Bovard

## Corona North

Kelly R. Bovard, Michael Dawson

## Corona South

Kelly R. Bovard, Tim O\'Brien

## El Casco

Pam M. Cossette

## Elsinore

Rachel M. Alvarez, Diane Burns

## El Toro

Anne G. Garcia

## Laguna Beach

Kelly R. Bovard, Roland Hall

## La Habra

Michael L. Dawson, Tim O'Brien, Rachel M. Alvarez, Kelly R. Bovard

## Lake Mathews

Van M. Diep, Ursula Edwards-Howells

## Lakeview

Rachel M. Alvarez, Pam M. Cossette

## Murrieta

Rachel M. Alvarez, Greg Morton

## Newport Beach

Michael L. Dawson, Diane Burns

## Orange

Kelly R. Bovard, Teddy Bunyapanasarn

## Perris

Kelly R. Bovard, Rachel M. Alvarez

## Prado Dam

Kelly R. Bovard

## Riverside East

Michael Dawson, Tim O\'Brien

## Riverside West

Rachel M. Alvarez, Van M. Diep

## Romoland

Kelly R. Bovard, Gregory Morton

## San Juan Capistrano

Kelly R. Bovard, Roland Hall

## Santiago Peak

Kelly R. Bovard, Michael L. Dawson

## Sitton Peak

Rachel M. Alvarez, Roland Hall

## Sunnymead

Van M. Diep, Ursula Edwards-Howells

## Steele Peak

Rachel M. Alvarez, Van M. Diep

## Tustin

Rachel M. Alvarez, Diane Burns, Anne G. Garcia

## Wildomar

Rachel M. Alvarez, Fernando H. Keller

## Winchester

Kelly R. Bovard, Gary W. Patt

## Yorba Linda

Kelly R. Bovard, Michael L. Dawson, Teddy Bunyapanasarn