U.C.H. LIBRARY
SHELL RESOURCES OF THE
COAST RANGES PROVINCE,
CALIFORNIA
Jftn 1 5 1979
I
BULLETIN 197
CALIFORNIA DIVISION OF MINES AND GEOLOGY
Sacramento, California, 1978
m
LIMESTONE, DOLOMITE, AND
SHELL RESOURCES OF THE
COAST RANGES PROVINCE,
CALIFORNIA
By
Earl W. Hart
1978
BULLETIN 197
CALIFORNIA DIVISION OF MINES AND GEOLOGY
1416 NINTH STREET, SACRAMENTO, CA 95814
STATE OF CALIFORNIA
EDMUND C. BROWN |R.
GOVERNOR
THE RESOURCES AGENCY
HUEY D. JOHNSON
SECRETARY FOR RESOURCES
DEPARTMENT OF CONSERVATION
PRISCILLA C. CREW
DIRECTOR
DIVISION OF MINES AND GEOLOGY
IAMES F. DAVIS
STATE GEOLOGIST
ll
CONTENTS
Page
ABSTRACT v
PREFACE vi
INTRODUCTION 1
Development ond Production 1
Deposit Descriptions 2
Samples and Chemical Analyses 2
Reserves 2
Definitions 2
Purpose ond Time of Investigation 3
Acknowledgments 3
NORTHERN COAST RANGES REGION (A) 5
Humboldt District (A-l) 5
Mendocino District (A-2) 7
Clear Lake District (A-3) 8
CENTRAL COAST RANGES REGION (B) 11
Healdsburg District (B-l) 12
North Bay District (B-2) 13
San Francisco Bay District (B-3) 18
Santa Clara District (B-4) 35
Santa Cruz District (B-5) 42
SOUTHERN COAST RANGES REGION (C) 53
Gabilon Range District (C-l) 54
Panoche Hills District (C-2) 73
Northern Santa Lucia Range District (C-3) 74
Porkfield-Coalinga District (C-4) 82
Southern Santa Lucia Range District (C-5) 83
Santa Ynez District (C-6) 92
REFERENCES 98
INDEX TO DEPOSITS 101
ILLUSTRATIONS
Plote 1 Mop of limestone and dolomite deposits ond districts of the Coast Ranges regions:
northern (A), central (B), and southern (C) Pocket
Plote 7 Map of limestone ond dolomite deposits, northern Gabilan Range Pocket
Page
Figure 1 Index map of Coast Ranges limestone and dolomite province 2
Figure 2 Map showing distribution of oyster shells in southern San Francisco Bay 26
Figure 3 Mop of Permanente and Monte Bello Ridge limestone deposits 39
Figure 4 Map of limestone deposits near Santa Cruz 44
Figure 5 Map showing distribution of Sur Series carbonate rocks, northern Santa Lucia Range 75
Figure 6 Geologic map of Pico Blanco limestone deposit, Monterey County 80
Figure 7 Geologic map of Dubost limestone deposit. Son Luis Obispo County 85
Figure 8 Geologic mop of Lime Mountain limestone deposit, San Luis Obispo County 88
Figure 9 Mop of Sierra Blanco Limestone, Santa Barbara County 97
iii
Illustrations (continued)
Page
Table 1 Production of limestone, dolomite, and shells in Coast Ranges, by formations 1
Table 2 Chemical analyses, Marin County 16
Table 3 Chemical onalyses, Napa Junction deposit, Napa County 17
Table 4 Chemical onalyses. Lime Ridge deposits. Contra Costa County 21
Table 5 Chemical analyses, Rockawoy deposit, San Mateo County 24
Table 6 Summary of producers and processors of shells, southern San Francisco Bay 27
Table 7 Chemical analyses, San Francisco Boy shells 29
Table 8 Chemical analyses, Permanente deposit, Santa Clara County 41
Table 9 Chemical analyses, Cowell Home Ranch, Holmes, and IXL deposits, Santa Cruz County 47
Table 10 Chemical analyses. Pacific Limestone Products deposit, Santa Cruz County 50
Table 11 Chemical analyses. Bird Canyon ledge, San Benito County 56
Table 12 Chemical analyses. East Gabilan deposit, Monterey County 57
Table 13 Chemical analyses, Garner-Harris deposits, San Benito County 60
Table 14 Chemical analyses, Palmtag-Harris deposits, San Benito County 70
Table 15 Chemical analyses, Tulare Formation, Fresno county 74
Table 16 Chemical analyses, Junipero Serra deposits, Monterey County 78
Table 17 Chemical analyses, Pico Blanco deposit, Monterey County 81
Table 18 Chemical analyses. Lime Mountain deposit, San Luis Obispo County 89
Table 19 Chemical analyses, Navajo deposits, San Luis Obispo County 91
Table 20 Chemical analyses, El Jaro deposits, Santa Barbara County 93
Table 21 Chemical analyses. Sierra Blanca deposit, Santa Barbara County 96
Photo 1 Shell barrier beach, western margin San Francisco Bay 28
Photo 2 Close-up of shells of barrier beach, San Francisco Bay 28
Photo 3 Bay Shell Company shell processing plant at Alviso 30
Photo 4 Ideal Cement Company dredge and barge, San Francisco Bay 32
Photo 5 Self-propelled dredge and barge of South Bay Dredging Company 34
Photo 6 Quarry in cherty limestone of Franciscan Formation at Permanente deposit 4 1
Photo 7 Cement plant of Kaiser Cement and Gypsum Corporation at Permanente 4 1
Photo 8 Quarry in crystalline limestone at San Vicente deposit of Pacific Cement and Aggregates
Division, Lone Star Cement Corporation 45
Photo 9 Dry process cement plant of Pacific Cement and Aggregates Division, Lone Star Cement
Corporation, at Davenport 45
Photo 10 Hamilton limestone deposit, upper quarry 61
Photo 11 Hamilton limestone deposit, lower quarry 62
Photo 12 Old lime kiln near Hamilton Ranch deposit, San Benito County 62
Photo 13 Natividad dolomite quarry and plant, Monterey County 67
Photo 14 Dolomite processing plant of Kaiser Refroctories at Natividad 68
Photo 15 Eaton and Smith limestone quarry in Vaqueros Formation at Lime Mountain deposit, San Luis
Obispo County 87
iv
ABSTRACT
This report covers the Coast Ranges province — a 30,000-sqJare-mile area of coastal California
between the Oregon border and the city of Ventura, nearly 600 miles southeast. To facilitate discussion
of the limestone, dolomite, and shell resources, this elongate province is divided into three regions —
northern, central, and southern. The deposits are grouped into 14 districts within these regions.
The large population and high industrialization of the San Francisco Bay area, located in the central
Coast Ranges region, has provided the main stimulus for exploration and development, particularly
of the larger deposits. However, numerous small deposits of limestone, including some very impure
ones, have been developed locally as sources of lime and crushed stone for construction uses.
Altogether, roughly 100 deposits of limestone, dolomite, and shells have been developed commercially
in the Coast Ranges province. A diversity of carbonate materials has been used, including metamorphic
crystalline limestone and dolomite (Sur Series), fine, dense cherty limestone (Franciscan Formation),
Quaternary spring deposits (travertine, calcareous tufa, onyx marble, and caliche), late Quaternary
shells (San Francisco Bay mud), hard bioclastic limestone (Vaqueros Formation), and dense, impure,
bituminous dolomite (Monterey Formation), plus a variety of mostly impure sedimentary limestones
ranging in age from Jurassic to Quaternary.
From 1850, when commercial production began, to 1968, an estimated 169 million tons of limestone,
dolomite, and shells were produced in the Coast Ranges province. Of this, more than 86 percent came
from the central Coast Ranges region around the San Francisco Bay district, and almost all of the rest
came from the southern Coast Ranges region. Geologically, 37 percent of the production was limestone
from the Franciscan Formation; 32 percent was crystalline limestone and dolomite from the Sur Series
and similar metamorphic rock units; 19 percent was oyster shells from San Francisco Bay; 7 percent
was from Quaternary spring-associated deposits; and about 4 percent was from other formations.
During the 1966-1968 period, there were 13 active operations at 1 1 different deposits and deposit
groups in the Coast Ranges. Eight of these operations were in the central region, and five were in
the southern region. The products were quarried and dredged and included: (1) limestone used for
cement, aggregate, road base, riprap, building stone, decorative material, soil conditioning, livestocx
feed, beet sugar refining, and glass manufacture; (2) shells used for cement, livestock feed, and soil
conditioning; and (3) dolomite used for refractory purposes, manufacture of magnesium compounds,
roofing and landscape rock, aggregate, road base, riprap, soil conditioning, marking athletic fields,
glass manufacture, whiting, and filter rock.
Reserves of raw carbonate materials other than those associated with deposits currently under
development are fairly limited in distribution and kind. The northern Coast Ranges contain only minor
reserves of limestone. The central Coast Ranges contain moderate to large reserves of cherty Francis-
can limestone, crystalline limestone, and shells associated with bay mud; however, most of the better
quality and larger deposits are already under development. Limestone reserves of the southern Coast
Ranges region, particularly at the Pico Blanco deposit in Monterey County, are very large. High-quality
crystalline dolomite in the southern region is present in modest but economically important amounts;
less pure dolomite of the Monterey Formation is much more extensive, but development has been
limited largely to aggregate and other construction uses. In spite of the obvious economic potential
of certain deposits in the Coast Ranges, development of several is severely limited because of
conflicting interests with urban, recreational, and wilderness developments and plans.
V
PREFACE
Because ot the long delay in issuing this bulletin, the reader should be aware that most of the data
presented are based on field work and literature review conducted from 1962 to 1965. The reader
is referred to the paragraph under Purpose and Time of Investigation (p. 3) for a more complete
explanation.
Despite the delay in publication, the material presented here in believed to be largely valid and
useful.
EARL W. HART
April 16, 1978
V I
LIMESTONE, DOLOMITE, AND SHELL RESOURCES OF THE
COAST RANGES PROVINCE, CALIFORNIA
By Earl W. Hart
INTRODUCTION
This report includes a discussion of all of the known
limestone, dolomite, and shell deposits of the north-
west-trending Coast Ranges, except those of the Frazi-
er Mountain area at the southeast end of the ranges.
The carbonate deposits of the Santa Ynez Mountains,
which are part of the Transverse Ranges, are included
with the deposits of the Coast Ranges for convenience
(figure 1).
The Coast Ranges carbonate province defined by
this report (figure 1) covers 30,000 square miles, near-
ly one-fifth of California. It extends southeasterly for
600 miles from the Oregon border to southwest Ven-
tura County and is at most 70 miles wide between the
Pacific Ocean and the Great Valley. The area is not
only extensive, but its complex geologic history has
permitted a wide variety of carbonate deposits to de-
velop. To facilitate discussion of the deposits, the
Coast Ranges are subdivided somewhat arbitrarily
into three subprovinces or regions — northern Coast
Ranges (A), central Coast Ranges (B), and southern
Coast Ranges (C). The deposits are discussed geo-
graphically from north to south by regions and by-
districts within each region (Contents and figure 1).
Deposits within each district are discussed in alpha-
betical order.
The deposits are located on the district maps by
number from north to south. The names of all depos-
its, including known synonyms, are listed alphabeti-
cally in the Index to Deposits at the end of this report
Development and Production
Approximately 100 carbonate deposits have been
productive in the Coast Ranges province. In addition,
many more undeveloped deposits have been cited in
the literature as possessing economic potential. Be-
cause of extensive changes in transportation, mining,
processing, and other economic factors over the years,
the majority of the deposits no longer are of economic
interest as sources of industrial limestone and dolo-
mite. However, some of these deposits may be of local
value as sources of crushed stone or building stone or
may be useful in some other way.
Total production of limestone, dolomite, and shells
in the Coast Ranges through 1968 approximates 169
million tons. Referring to table I, it can be seen that
the central region has accounted for 86 percent of the
total production. The principal limestone reserves
and all of the dolomite reserves, however, are located
in the southern region although substantial reserves of
limestone and shells are available in the central region.
In the 1966-1968 period, there were 1 3 active commer-
cial producers of limestone, dolomite, and shells in the
Coast Ranges province. The average yearly produc-
tion of about 6 million tons was obtained from the
following 11 deposits (with designated districts):
Tolenas Springs (North Bay); San Francisco Bay
Shell and Rockaway (San Francisco Bay); Per-
manente (Santa Clara); San Vicente and Pacific Lime-
stone Products (Santa Cruz); Bryan and
Pearce-Twohy, Natividad, and VVestvaco (Gabilan
Range); Lime Mountain (Southern Santa Lucia); and
Missile City (Santa Ynez) (see plate 1).
Table 1. Estimated total production of limestone, dolomite, and
shells for the Coast Ranges, by regions and formations through
1968.
Estimated
production
Formation and principal net types (1,000,000 tons)
NORTHERN COAST RANGES (A)
Miscellaneous limestone Minor
CENTRAL COAST RANGES (B)
"Sur Series", crystalline limestone '4
Franciscan Formation, limestone and associated chert 62. 5
Quaternary travertine, calcareous tufa, caliche 13
Quaternary shells of San Francisco Bay 1)
Miscellaneous and undetermined 2_5
Subtotal 145.0
SOUTHERN COAST RANGES REGION (C)
Sur Series, crystalline limestone 9
Sur Series, crystalline dolomite 10.5
Vaqucros Formation, limestone 15
Monterey Formation, dolomite and dolomitic limestone 2
Miscellaneous limestone and marl I
Subtotal 24.0
Grand total 169 0
1
2
California Division of Mines and Geology
Bull. 197
OREGON
Figure 1. Index map of Coast Ranges limestone and dolomite province.
Deposit Descriptions
An attempt was made to describe all of the deposits
in a systematic manner; and, where possible, data are
provided on location, ownership, history, geology, de-
velopment, production, estimated reserves, and perti-
nent references — generally in that order.
Almost all of the large deposits and many of the
small ones in the Coast Ranges province were exam-
ined by this writer or Oliver E. Bowen (geologist,
Division of Mines and Geology, from 1947 to 1968;
now a consulting geologist). This investigator's prop-
erty visits were conducted mainly between April 1962
and February 1964, whereas Bowen's visits extend
over a much longer period (mainly before 1962).
Limestone, dolomite, and shell deposits not examined
include numerous minor ones plus some that have
been adequately described in the literature and a few
that could not be reached or located. Virtually all
deposits cited previously in the literature, regardless
of their economic significance, are considered in this
report.
Samples and Chemical Analyses
Most chemical analyses presented herein are of
hand or grab samples believed by the sampler to be
representative of the compositional variations at a
given carbonate deposit. The representativeness of a
given sample or set of samples, however, depends on
the acuity of the sampler, the accessibility and extent
of deposit outcrops, and the degree of weathering. In
some cases, processed or partly processed carbonate
materials (shells and other materials) were sampled
from stockpiles and waste piles, sometimes to check
beneficiated and waste materials or simply because
some deposits were inaccessible. For a variety of rea-
sons, many deposits were not sampled at all.
Analyses of samples by commercial laboratories
were made prior to 1960. Most, if not all, of these
analyses were by wet chemical methods. Most analy-
ses since I960 were made by Division of Mines and
Geology laboratory staff. Until mid- 1963, these were
done mainly under the supervision of Charles W.
Chesterman, using rapid analytical techniques. In
1963, analytical techniques were changed to a com-
bined wet chemical and x-ray fluorescent method un-
der the supervision of Matti Tavela. Analyses made by
various companies and individuals are believed to
have been done by wet chemical methods.
Because of the above variables — particularly the in-
herent sampling problems — the chemical analyses
presented herein should be viewed only as a general
guide to the composition of the deposits sampled.
Reserves
All reserve figures for deposits described herein are
estimates based on limited data — generally not includ-
ing drill data. These estimates are of carbonate materi-
als believed to be recoverable under present (1972)
economic and mining conditions. The type of carbon-
ate material (limestone, limestone and chert, dolo-
mite, shells) comprising each deposit is indicated
where reserve figures are estimated. Where little or no
subsurface data are available or where deposits are
poorly exposed, estimated reserves are presented in
tons per foot of depth, and no attempt is made to
estimate economically recoverable material.
Definitions
Carbonate rock, as used herein, is a general term
that includes all limestone, dolomite, shell, travertine,
calcareous tufa, onyx, caliche, marl and unspecified
mixtures of these. Definitions of the more specific
terms used in this report are:
• limestone: A sedimentary rock composed mostly of detrital or
chemically deposited calcite (calcium carbonate). Metamorphosed
limestone (marble) is recrystallized calcite and is referred to as
crystalline limestone. Bioclastic limestone is a limestone composed
largely of firmly cemented fragmental fossil debris.
• dolomite: A sedimentary rock, often diagenetically altered,
composed mainly of the mineral dolomite (double carbonate of
calcium and magnesium). A metamorphosed dolomite (marble or
dolomite marble) is referred to as crystalline dolomite.
• shell deposits: Unconsolidated to weakly consolidated accumu-
lations of shells and shell debris; pure to very impure calcium carbon-
ate.
• travertine: Fine to sometimes coarse crystalline, dense to vuggy,
banded rock composed of calcium carbonate; formed from surface
water at or near the earth's surface, generally near springs.
• calcareous tufa: A very porous, commonly fibrous variety of
travertine.
• onyx or onyx marble: A fine-grained, delicately banded variety
of travertine.
• caliche: An impure carbonate deposit formed at or near the
surface in porous soils. May be associated with calcareous tufa or
other spring deposits.
1978
i imi stoni in i in coast Rang) s
3
• marh An impure fine-grained limestone or dolomite containing
substantial amounts of noncarbonate minerals or grains.
The above types of carbonate materials are not al-
ways distinct and some materials may be intermediate
betw een two or three of the above classes. Also, many
deposits contain two or more distinct kinds of carbon-
ate materials.
Purpose and Time of Investigation
This investigation was initiated by the California
Division of Mines and Geology in 1962 as part of a
statewide survey of the limestone, dolomite, and shell
resources of California under the supervision of Oliv-
er 1 Bowen in association with several other Division
geologists. At that time, the study was divided areally
into six carbonate provinces — Klamath Mountains,
Coast Ranges, Sierra Nevada, Basin Ranges, Mojave
Desert, and Transverse Ranges and Peninsular
Ranges — and, together with an introductory part
(Bowen, Evans, and Gray, 1973), the seven-part re-
port was intended to be published as one Bulletin. The
initial report on the Coast Ranges province was sub-
mitted for publication processing by this writer in
March 1965. Because of problems encountered in tim-
ing and coordinating the bulky, multi-authored report
and the delays in completing parts of the investiga-
tion, it was decided to publish the various parts sepa-
rately as they became ready. This report was
considerably delayed in the meantime and was reor-
ganized in October 1969. At that time, statistics were
updated through 1968 and a little descriptive data add-
ed. Significant information obtained since October
1969 has been included as footnotes.
Acknowledgments
Unpublished field data and sample analyses sup-
plied by Oliver E. Bowen and other geologists of the
California Division of Mines and Geology, as well as
employees of the U.S. Geological Survey and several
other agencies and private companies, are gratefully
acknowledged. The many courtesies provided by nu-
merous operators and property owners are also ap-
preciated All available published and unpublished
data were used to evaluate the carbonate deposits and
are cited wherever practical. The author is indebted to
Oliver E. Bowen and Richard M. Stewart for critically
reviewing the manuscript prior to publication.
NORTHERN COAST RANGES REGION (A)
This region is the northernmost of three arbitrary
subdivisions of the Coast Ranges limestone, dolomite,
and shell province. It encompasses all of the Coast
Ranges in Colusa, Del Norte, Glenn, Humboldt, Lake,
Mendocino, Tehama, Trinity, and Yolo Counties. The
region is flanked on the west by the Pacific Ocean, on
the east by the Sacramento Valley, and on the
northeast by the Klamath Mountains (figure 1 and
plate 1 ) . A narrow strip of the northern Coast Ranges
extends northward into Oregon. The region is rather
sparsely populated, the largest city being Eureka with
28,137 people in 1960. The economy is based largely
on lumbering, recreation, agriculture, and fishing. In
general, the region is mountainous and many parts are
not easily accessible. Major transportation facilities
are limited by the north- and northwest-trending
ranges although most of the region is served by high-
way, rail, or port facilities.
There are few limestone and no dolomite deposits
of economic interest even though occurrences of car-
bonate rock are common. Limestone has formed un-
der a variety of conditions since Late Jurassic time.
Perhaps the oldest limestone occurs as thin beds and
lenses in shale of the Knoxville Formation (Upper
Jurassic) exposed in the low hills of the Coast Ranges
that flank the Sacramento Valley. Minor beds, lenses,
and concretions also are found in Cretaceous shales
that conformably overlie the Knoxville. Much of the
rest of the northern Coast Ranges is underlain by sedi-
mentary and volcanic rocks generally assigned to the
Franciscan Formation of Late Jurassic and Cretaceous
age. These rocks consist of graywacke, chert, shale,
volcanic rocks, and minor amounts of limestone. Most
of the limestone is thin bedded, usually interstratified
with chert and commonly associated with altered vol-
canic rocks (greenstone). In a few cases, massive lime-
stone is associated mainly with graywacke of the
Franciscan Formation.
Limestone that is more or less impure is found in
the marine Pullen Formation (Miocene and/or Plio-
cene) near Fureka and as lake beds or marls in the
Tehama and Cache Formations (Pliocene and/or
Pleistocene) that lie east of Clear Lake and along the
western side of the Sacramento Valley. In addition,
numerous surficial deposits of travertine, onyx mar-
ble, and calcareous tufa were formed in the vicinity of
mineral springs during Quaternary time. Beds of oys-
ter shells mav exist in the mud in modern or young
fossil bays along the coast although no such deposits
have been reported.
About 10 deposits have been utilized for limestone
in the northern Coast Ranges. Total production is not
known but probably does not exceed a few tens of
thousands of tons of limestone. Practically all of this
was used as agricultural limestone, to make lime for
construction use, and for mercury retorting. The only
deposit of sufficient size and purity to be of significant
economic interest is the Fashauer Ranch deposit in
Mendocino County. Some of the other deposits may
be of local use, particularly in road construction or for
agricultural purposes. Some of the travertine and
other surficial deposits, as well as the red limestone of
the Franciscan Formation, may be of interest as
sources of ornamental and architectural materials.
The red Franciscan limestone has been referred to as
the Lavtonville-type limestone and is described in de-
tail by Bailev et al. (1964, p. 68-77) and Garrison and
Bailey (1967, p. B94-B100).
The limestone deposits of the northern Coast
Ranges are shown on plate 1 A and are discussed below
in alphabetical order within each district. The dis-
tricts of the region are listed in geographic order from
north to south.
HUMBOLDT DISTRICT (A l)
Minor amounts of limestone from the Richtcr,
Moore, and McClellan Ranch deposits have supplied
local agricultural needs at times in the past. Some lime
also was made at the Jacoby Creek deposit many years
ago. However, none of the known deposits is large
enough to be considered of significant future value.
Hackett deposit. Location: N'/2 sec. 16, T. 1 N., R.
1 W., H., 4'/2 miles west-southwest of Rio Dell; Scotia
1 5-minutc quadrangle. Ow nership: Mel Hackett, \ er-
non Hackett, et al, Rio Dell (1963).
5
6
California Division of Mines and Geology
Bull. 197
White, gray, and red limestone is described by B. A.
Ogle (1953, p. 82-83) as a "continuous bed" traceable
for half a mile northwest of the west fork of Howe
Creek, where it crops out strongly. The bed is report-
ed to be 75 feet thick, to strike N 60° W, and to dip 45°
N. Others (Averill, 1941, p. 516; Logan, 1947, p. 237)
had previously reported similar limestone to crop out
as a single 20-by-30-foot exposure in the same vicinity.
This writer was unable to locate any limestone out-
crops on the west fork of Howe Creek in August 1963.
Neither were the owners aware of any significant
limestone outcrops in the vicinity, where they have
worked and hunted for many years. No positive expla-
nation can be offered for this anomalous "disappear-
ance". However, it is possible that floods and
landslides, created by the major storms of 1955-56,
destroyed or covered the exposures in the creek. This
suggestion would be more plausible if the Hackett
deposit, where traversed by Howe Creek, were com-
prised of small, detached masses of limestone rather
than continuous masses.
In 1963, the west fork of Howe Creek contained
scattered boulders of light dove-gray and dark red-
dish-brown limestone. This float could be traced near-
ly a quarter of a mile upstream from its main conflu-
ence to a small northwest tributary gulch. At this
point, there was an increase of limestone float, and
some limestone fragments were observed in a land-
slide exposed in the gulch. Above the gulch, only a few
boulders of a dark gray limestone were noted. Most of
the limestone float is very similar to limestone of the
Franciscan Formation, being fine grained, dense,
sometimes containing Foraminifera, and generally
brecciated or sheared. The visible impurities appear to
be silica and iron oxide minerals, but most of the light-
colored limestone appears to be of a high-calcium
type.
There is no record of development of this limestone.
Moreover, the existence of a significant limestone
deposit has not been established.
Jacoby Creek deposit. Location: NW'/4NW'/ sec.
13, T. 5 N., R. 1 E., H., 2'/2 miles southeast of Bayside
and 7 miles east of Eureka; Eureka 1 5-minute quadran-
gle. Ownership: F. B. Barnum, Inc., and R.W. Bull,
Eureka (1941).
Limestone from this deposit was burned for lime
many years ago, as shown by the remnant of an old
brick kiln nearby (Averill, 1941, p. 516). The deposit
was tested as a source of raw material for cement prior
to 1916 but was never developed commercially for that
purpose.
The deposit reportedly consists of a single exposure
50-by-20-by-l 5 feet. Samples collected by Oliver E.
Bowen show the limestone to be dense, fine grained to
partly crystalline, grayish tan to light olive, and mot-
tled white with irregularly veined calcite. One sample
contained numerous fossil fragments which suggest a
Late Cretaceous age. Although the limestone appears
to be high in calcium and relatively free from impuri-
ties, the deposit is too small to be of more than local
interest.
Other references: Lowell, 1916, p. 393; Logon, 1947, p. 238; Irwin, 1960,
p. 37.
Johnston deposit. Location: Sees. 4 and 9, T. 2 S.,
R. 1 W., H., 5 miles east of Petrolia and 12 miles south-
southeast of Scotia; Scotia 1 5-minute quadrangle.
Ownership: Johnston Estate and T. A. Johnston, Pe-
trolia (1941).
Small outcrops of limestone, presumably of the
Franciscan Formation, are exposed intermittently for
2 miles in a northwest direction. The deposits are
situated in a remote area within or close to the Mattole
fault zone. The limestone has not been worked and
probably is not present in economic amounts.
References: Averill, 1941, p. 517; Logan, 1947, p. 238.
McBride Ranch deposit. Location: Sees. 26 and
27, T. 1 N., R. 2 W., H., on Southmayd Ridge; Cape
Mendocino 1 5-minute quadrangle. Ownership:
McBride Ranch.
According to Robert D. Nason of the U.S. Geologi-
cal Survey (personal communication, 1967), a bed or
series of beds of coarse-crystalline white limestone up
to 20 feet thick crops out for over a mile. The beds
strike northwest and stand vertically. The associated
rocks are chiefly gray wacke and chert. The deposit is
undeveloped.
McClellan Ranch deposit. Location: Sec. 5, T. 1
N., R. 1 W., H., 5 to 6 miles west of Rio Dell and 7
miles south-southwest of Fortuna; Scotia 1 5-minute
quadrangle. Ownership: E.S. McClellan (1941).
The deposit has been described as soft, white, po-
rous, calcareous tufa covering an acre of land to a
depth of 3 feet (Averill, 1941, p. 517). It is reported to
contain 99% calcium carbonate and has been used on
the McClellan Ranch (Ogle, 1953, p. 83).
Other reference: Logan, 1947, p. 238.
Moore deposit. Location: Sec. 19(?), T. 5 N., R. 2
E., H., 5 miles southeast of Bayside and 8 miles east of
Eureka; probably Blue Lake 1 5-minute quadrangle.
Ownership: J. A. Moore, Blue Lake (1916).
A small deposit of limestone situated near the Jaco-
by Creek deposit is reported to have been quarried for
local farm use in 1913. An analysis of the limestone
shows 53.61% CaO, 1.41% Si02, 0.35% Fe,0(, 0.56%
A120,, and a trace of MgO.
References: Lowell, 1916, p. 394; Averill, 1941, p. 516; Logon, 1947, p.
238.
Parkhurst Ridge deposit. Location: Sec. 2 3, T. 2
S., R. 1 W , II., 2 miles northeast of Upper Mattole
School; Scotia 1 5-minute quadrangle. Ownership: Ben
Etter, Honeydew ( 1967).
According to Robert D. Nason of the U. S. Geologi-
cal Survey (personal communication, 1967), the
deposit crops out over several acres on Parkhurst
Ridge. The limestone is fine grained, red, and ferrugi-
1978
Limestone in hie Coast Rav.i s
7
nous. The beds are poorly defined tnit appear to strike
generally northwest and to dip nearly vertically. The
enclosing wall rocks are pillow basalt. The attractive
appearance of the rock may make it marketable for an
ornamental garden or construction stone. The deposit
is undeveloped.
Richter (Rickter) deposit. Location: NE'^SE1/
sec. 11, T. 1 N., R. 1 W., H., 2 miles southwest of Rio
Dell; Scotia 1 5-minute quadrangle. Ow nership: VV. G.
Fritz and A. and O. Richter, Rio Dell (1963).
The Richter deposit is situated just west of the crest
of a northwest-trending ridge and is readily accessible
by road from Rio Dell. Low limestone outcrops and
float cover an area roughly 600 feet long in a northeast
direction by 150 to 200 feet wide. The pattern of out-
crops suggests that the deposit is gently dipping. It is
associated with siltstone and calcareous sandstone of
the Pullen Formation of late Miocene to early Plio-
cene age (Ogle, 1953, p. 82). The limestone is charac-
teristically buff colored, hard, fossiliferous,
bituminous, sandy, and silty. Chemical analyses made
by Matti Tavela and Lydia Lofgren from samples ob-
tained by this writer in 1963 show the limestone to be
somewhat impure:
Ign.
Sample CM MgO SKI AI.O, Fe.O, k..O P_.(). loss
R-l 48.1% 0.73% 9.2% 0.50% !.() % 0.20% 0.06% 39.7%
R-2 45.2 0.81 7.4 1.2 0.78 0.25 0.06 41.6
Development of the deposit is limited to a single
quarry 75-by-25 feet with a maximum face of 10 feet.
Minor amounts of limestone were produced for agri-
cultural purposes beginning about 1915. There has
been no recent production. The limestone deposit ap-
pears to be a thin cap, and reserves are probably small.
Other references: Averill, 1941, p. 517; Logon, 1947, p. 238.
White Woman deposit. Location: NF.'/4 sec. 29, T.
4 S., R. 5 E., H., 9 miles east of Garberville and l'/2
miles east-northeast of Harris; Alderpoint 1 5-minute
quadrangle. Ownership: A. A. Smith, Harris (1963).
Small exposures of Franciscan limestone are report-
ed at intervals for a quarter of a mile. The largest of
these forms a cliff 35 feet long and 10 feet high (Ave-
rill, 1941, p. 518). The deposit consists of Calera-type
limestone and thin chert interbeds. The limestone is
typically dense, fine crystalline, light dove gray to pale
grayish brown, and apparently high in calcium. A
sample submitted by the owner was analyzed by the
Division of Mines and Geology laboratory staff in
1963 and showed the following chemistry:
Ign
Simple OO MgO SKI AI.O, Fe.O, K.O P.O. loss
WW- 1 .. 53.8% 0.30% 2.5% 0.44% 0.23% 0.06% 0.07% 43.0%
The deposit has never been worked. There appears
to be little economic potential, as reserves are un-
doubtedly small and the deposit is poorly situated
with regard to transportation, accessibility, and mar-
kets.
Other reference: Logan, 1947, p. 239.
MENDOCINO DISTRICT (A-2)
The largest known limestone deposit in the north-
ern Coast Ranges is the Fashauer Ranch deposit of
western Mendocino County. The deposit is un-
developed, as are the Fisher Ranch and L sal deposits.
Only the (^iiinan Ranch deposit has been worked,
with total production to 1968 amounting to about 700
tons of agricultural limestone.
Fashauer Ranch deposit. Location: NYV1/ sec. 2,
T. 14 N., R. 16 W., M.D., 6 miles east-southeast of Elk;
Navarro 1 5-minute quadrangle. Ownership: Anthony
and Francis Fashauer, Greenwood Road, F.Ik (1962).
The Fashauer Ranch limestone is exposed in a poor-
ly accessible area just south of an east tributary of
Greenwood Creek at an elevation of 700 feet. It consti-
tutes a northwest-trending deposit, possibly 600 feet
long by 200 to 300 feet wide. Although poorly strati-
fied, the deposit appears to dip steeply southwest into
the hill. The limestone is pale grayish brown, faintly
mottled, finely crystalline, bituminous, fractured, and
cut by veinlets of calcite and quartz. No chert beds
were noted in the deposit, although the limestone and
surrounding gray wacke may be part of the Franciscan
Formation. Smaller limestone bodies similar to the
Fashauer Ranch deposit are said to exist on nearby
ranches. Chemical analyses made of five samples taken
over a length of 200 feet across the strike of the deposit
by L'.S. Steel Company indicate the limestone to be of
uniform quality (personal communication with the
owners, 1962). All of the samples showed at least 54%
CaO and averaged 1.55% SiO,, 0.65% MgO, 0.20%
Fe;(),, and 0.45% A120,. Three random samples col-
lected along the northeast side of the deposit and
analyzed by Lydia Lofgren in 1962 show similar
chemistry:
Ign.
Sample CO MgO SiO: AI.O, Fe.O, P.O. loss
Fas-1 54.50% 0.43% 1.42% 0.10% 0.13% 0 03% 43 18%
Fas-2 53.25 0.85 2.86 0.12 0.11 0.03 42.30
Fas-3 54.00 0.51 1.81 0.21 0.19 0.03 42.88
There has been no development of the deposit, prin-
cipally because of its inaccessibility and distance from
markets It appears to contain one of the largest re-
serves of good quality limestone in the northern Coast
Ranges, probably in the order of 1 to 2 million tons.
However, more prospecting is needed to determine
the size, distribution, and presence or lack of such
deleterious materials as chert interbeds in the lime-
stone.
Fisher Ranch deposit. Location: NW'/( sec. 36, T.
22 N., R. 15 W., M.D., 2 miles north of Laytonville;
Laytonville 1 5-minute quadrangle. Ownership: Mar-
shall and Pauline C. Fisher, Laytonville (1953).
8
California Division of Mines and Geology
Bull 197
Limestone of the Franciscan Formation is exposed
as a series of outcrops along a low hill a few hundred
feet east of U.S. Highway 101. As indicated by expo-
sures and limestone float, the deposit extends over a
length of about 600 feet and a maximum width of 100
feet. The deposit consists of a sequence of well-bed-
ded, massive limestone interleaved with thin chert
beds and lenses. Consistent bedding exposures show
the deposit to strike N 10° E and dip 70 to 80° E.
Limestone along the west side of the deposit is typical-
ly rust red to reddish brown, dense, fine grained,
foraminiferal, and cut by numerous veinlets of calcite.
This part of the sequence grades easterly into yellow-
ish-gray, red-mottled limestone of otherwise similar
character. Both types of limestone appear to be high
in calcium, the only visible impurities being iron ox-
ide in the red'varieties and discrete shert beds. Similar
but smaller limestone deposits are exposed in road
cuts to the south, three-quarters of a mile north of
Laytonville.
A chemical analysis of the Fisher Ranch limestone
is reported to be 93.16% CaCO,, 0.39% MgCO,, 0.69%
Fe,0, and AlzO„ and 5.56% insoluble (Logan, 1947,
p. 254). Two additional analyses of the yellowish (FR-
1) and reddish (FR-2) limestone were made by Matti
Tavela and Lvdia Lofgren from samples collected by
this writer in 1963:
Ign
Simple S,Q, AW, Fe;Q, MgO CaO K,Q P.O, loss
FR-1 2 5% 0.07% 0.30% 0.38% 53.2% 0.00% 0.08% 43.2%
FR-2 1.0 0.00 0.43 0.84 53.8 0.00 0.07 43.6
There has been no development of the deposit, and
the limestone would have to be beneficiated for most
limestone uses. However, the limestone shows rather
striking colors and may be useful as a source of colored
granules or as a decorative material. The deposit is
readily accessible, but it is about 13 miles from the
nearest rail facility at Longvale. Reserves of limestone
are estimated to be 300,000 tons per 100 feet of depth.
Because of a maximum relief of approximately 50 feet,
reserves above local base level are relatively small.
Other references: O'Brien, 1953, p. 361; Irwin, 1960, p. 35, 43; Bailey and
others, 1964, p. 75.
Quinan Ranch deposit. Location: Sec. 26, T. 17
N., R. 13 W., M.D., 2 miles northwest of Laughlin and
10 miles north-northwest of Ukiah; Willits 15-minute
quadrangle. Ownership: Grace T. Post (1953).
This surficial deposit has been described by Logan
( 1947, p. 254) as terraces of travertine and calcareous
tufa formed from spring action near the top of a ridge.
The springs issue along a fault that strikes west and
dips 61° S. One terrace, at an elevation of 2,000 feet, is
2 50 feet long by 100 feet wide. To the east and 35 feet
below the first terrace, a lower terrace covers an acre
or less in area. This is developed by a pit 27-by-50 feet
with a depth of 10-to-15 feet. A 6- to 8-foot thick bed
of travertine, underlain by soil and angular rock frag-
ments, is exposed here. A chemical analysis made of
the travertine shows 94.97% CaCO,, 1.51% MgCO,,
0.24% Fe20, and A120,, and 3.20% insoluble (Logan,
1947, p. 254).
Northwest Pacific Lime and Sulphur Company
worked the deposit from 1930 to 1933. Based on the
size of the pit and the thickness of the deposit, produc-
tion must have been in the order of 700 tons. The
carbonate material was trucked a few miles to a mill
at Laughlin on the Northwestern Pacific Railroad.
Here, the material was crushed and pulverized for use
as a soil conditioner.
Other references: Averill, 1929, p. 462; O'Brien, 1953, p. 361.
Usal deposits. Location: Sees. 1 and 2, T. 23 N., R.
18 W., and sees. 26, 35, and 36, T. 24 N., R. 18 W., M.D.,
16 miles south of Garberville; Piercy 15-minute quad-
rangle. Ownership: Not determined.
About 30 small lenses of limestone comprising two
northwest-trending belts are mentioned in a report on
manganese by Trask et al. (1950, p. 146-147). The
limestone is light gray and fine grained, except near
the manganese ore, where the color is pinkish. Most of
the limestone lenses are less than 5 feet thick and 20
feet long, although one is 50 feet thick by 1 50 feet long.
The limestone is reported to be similar to the lime-
stone near Laytonville (Irwin, 1960, p. 43).
The limestone has never been used, and future de-
velopment is limited by the size of the lenses and the
remoteness of the area. However, other limestone
deposits may exist nearby.
CLEAR LAKE DISTRICT (A-3)
Deposits of the Clear Lake district lie in Glenn,
Colusa, Lake, and Yolo Counties (plate 1A). Small
amounts of limestone were produced many years ago
at the Manzanita and Wide Awake deposits, apparent-
ly for use in retorting mercury ore from the mines
near Wilbur Springs. A little limestone was also quar-
ried in Burns V alley as a source of lime in the late
nineteenth century. None of the deposits appears to
be of significant commercial value although some in-
terest has been shown recently in the surficial deposits
near Wilbur Springs as sources of decorative stone.
In addition to the deposits described below, lime-
stone has been reported from sec. 19, T. 1 1 N., R. 7 W.,
M.D., where the Knoxville Formation is exposed.
That same formation also is found in sec. 36, T. 13 N.,
R. 6 W., where the remains of an old lime kiln are
reported (Logan, 1947, p. 248).
Surficial deposits of notable size have been de-
scribed by Waring (1915, p. 183-184, 193-194, 196-
198) at Highland, Dinsmore, Hough, and Grizzly
Springs. A small, undeveloped deposit of onyx marble
lies near Hullville in sec. 12, T. 18 N., R. 10 W, M.D.,
(Bradley, 1916, p. 225).
Burns Valley deposit. Location: T. 13 N., R. 7 W.,
M.D., near Clear Lake Highlands; Lower Lake 15-
minute quadrangle. Ownership: Not determined.
1978
I.IMKSIOM IN 1 III CoASI K \\(.l S
Limestone from Burns Valley, north of the town of
Lower Lake, apparently supplied two lime kilns
0\a ned by the Sulphur Bank Mining Company in the
late 1800s (Crawford, 1894, p. 392). The source of lime
rock has not been determined but may be the marl or
limestone present in the Cache Formation. Limestone
near Clear Lake Highlands is described as micro-crys-
talline and dolomitic and occurs in several beds 1 to 10
feet thick (Anderson, 1936, p. 634).
Other references: Bradley, 1916, p. 206; Logan, 1947, p. 248.
Capay Valley deposits. Location: T. 10 N., R. 2
and 3 W., and T. 1 1 N., R. 3 W., M.D., 17 to 20 miles
west of Woodland; Guinda and Lake Berryessa 15-
minute quadrangles. Ownership: multiple; not deter-
mined.
Limestone and marl deposits in Capay Valley
between Capay and Guinda have been mentioned in
the literature, but they have not been developed. Most
of the hard limestone occurs as float on slopes and in
streams and probably is derived from the large cal-
careous concretions and lenses common to the Upper
Cretaceous shales. Analyses of float indicate the lime-
stone to be relatively high in calcium but somewhat
siliceous. The softer marl, reported from the foothills
along Cache Creek, is believed to be from fresh water
deposits locally present in the Plio-Pleistocene Te-
hama Formation.
The calcareous rocks of the lower Cache Creek area
are of variable chemistry, and the deposits generally
are too small to be of economic value. It is possible that
the soft marl may be of local interest for agricultural
purposes.
References: Bradley, 1916, p 368; Logan, 1947, p. 350.
Chalk Mountain deposit. Location: S'/2 sec. 12, T.
14 N., R. 7 W., M.D., 6 miles northeast of Clearlake
Oaks; Clearlake Oaks 15-minute quadrangle. Owner-
ship: Not determined.
A spring deposit of calcium carbonate on the north-
western side of Chalk Mountain extends for 100 yards
along the mountainside and for 75 feet downslope to
the North Fork of Cache Creek (Waring, 1915, p. 196-
197). There is no known development of this deposit.
Daniels deposit. Location: Sec. 21, T. 18 N., R. 6
W., M.D., 1 to 2 miles north of Stonyford and 20 miles
southwest of Willows; Stonyford 15-minute quadran-
gle. Ownership: Not determined.
A "ledge of white marble" that "may be traced for
a mile north and south along the east side of Stony
Creek" is reported by Aubury (1906, p. 99).
The geology of the Stonyford quadrangle was
mapped in detail by R. D. Brown, Jr., and Ernest Rich.
Brown states (1964, personal communication) he has
no record of limestone in sec. 21 and questions the
location or descriptive data given by early writers. It
is not likely such a distinct deposit would be over-
looked in the course of detailed geologic mapping.
I lowever, it is possible that thin lenses of limestone of
the Knoxville Formation are present locally in sec. 21.
Other references: Bradley, 1916, p. 198; Logan, 1947, p. 237.
Lambert Ranch deposit. Location: Sec. 20, T. 16
N., R. 5 W., M.D., 2'/; miles northwest of Leesville and
14 miles west of Cortena on the Southern Pacific Rail-
road; Wilbur Springs 15-minute quadrangle. Owner-
ship. Not determined.
Limestone from this deposit was burned for lime
about 1889 (Aubury, 1906, p. 66). From the location
given, the limestone probably is from the lower part
of a thick sequence of Lower Cretaceous sedimentary
rocks.
Other references: Bradley, 1916, p. 179; Logan, 1947, p. 220.
Manzanita deposit. Location: NE1/, sec. 29, T. 14
N., R. 5 W., M.D., half a mile west of Wilbur Springs
and 17 miles southwest of Williams; Wilbur Springs
15-minute quadrangle. Ownership: Not determined.
A southeast-trending bed of crystalline limestone is
reported from the western part of the Manzanita mer-
cury mine property. This property is underlain by the
Knoxville Formation, which sometimes contains thin
beds of limestone and marl interbedded with shale.
The limestone was produced in a small way for local
use in the early 1900s.
References: Forstner, 1903, p. 41; Aubury, 1906, p. 66; Bradley, 1916, p.
179; Logan, 1947, p. 220.
Nye deposit. Location: Sees. 1 and 12, T. 18 N., R.
8 W., M.D., 28 miles west of Willows; Stonyford 15-
minute quadrangle. Ownership: Not determined.
A deposit of onyx marble is reported in the south-
west part of Glenn County on the west side of Saint
John Mountain. The property, which was part of the
J.M. Nye Ranch, is not known to be developed.
References: Bradley, 1916, p. 198; Logan, 1947, p. 237
Wide Awake deposit. Location: SE'/4 sec. 29 or
SW>/4 sec. 28, T. 14 N., R. 5 W., M.D., 1 mile southw cm
of Wilbur Springs and 1 7 miles southwest of Williams;
Wilbur Springs 15-minute quadrangle. Ownership:
Not determined.
A deposit of limestone composed entirely of shells
is reported on the Wide Awake quicksilver property.
This was used locally prior to 1916. Other shell depos-
its in thin beds arc mentioned as occurring in the same
vicinity, one near the top of the hill in NE1/, sec. 28.
None of these deposits has been worked in recent
years, and they probably are not of commercial inter-
est.
References: Goodyeor, 1890, p. 160, 161, Forilner, 1903, p. 42, Bradley,
1916, p. 179; Logan, 1947, p. 220.
Wilbur Springs deposits. Location: W'/2 T. 14 N.,
R. 5 W., and adjacent part of T. 14 N., R. 6 W., M.D.;
Wilbur Springs 15-minute quadrangle. Ownership:
Not determined.
Onyx marble, aragonite, calcareous tufa, and other
types of carbonate material have been reported from
10
California Division of Mines and Geology
Bull 197
several localities northwest and west of Wilbur
Springs. The following occurrences have been report-
ed:
1. Brown oragonite from a thin vein at the "head of Sulphur
Creek" was once shipped to England for sale. The vein was
situated on 48 acres of land owned by California Onyx Com-
pany (Irelan, 1888, p. 159) .
2. Brown, delicately banded aragonite, referred to as "Brown's
agate", came from a locality about a mile west of Wilbur
Springs where the material occurred as float (Goodyear, 1890,
P- 156).
3. Hard, white calcium and magnesium carbonate rock, with en-
closed shale fragments, is exposed as a prominent ledge below
the Judge Moor tunnel near the Elgin mercury mine (Waring,
1915, p. 105-106|.
4. A ledge of brown onyx marble crosses the creek half a mile
upstream (W'/j sec. 13, T. 14 N., R. 6W.) from the Elgin mine.
"The deposit has not been worked commercially" (Waring,
1915, p. 106).
5. A "capping" of brown, bonded onyx marble a foot thick, 20
feet wide, and 150 feet long is reported to lie a mile north of
the Elgin mine. This deposit was located in 1929 and was known
as the Warwick group of claims (Logan, 1929, p. 292).
None of the deposits appear to have significant poten-
tial as sources of limestone, but some may be of inter-
est as sources of ornamental material. It is reported
that one of the deposits near the Elgin mine was
worked in a small way in the early 1960s as a source
of decorative stone.
Other reference: Logan, 1947, p. 220.
Unnamed deposit (near Abbott mine) . Location:
Near NE'/4 sec. 31, T. 14 N., R. 5 W., M.D., 18 to 19
miles southwest of Williams; Wilbur Springs 15-
minute quadrangle. Ownership: Not determined.
Limestone has been reported near the Abbot mer-
cury mine but has never been described. Perhaps it is
related to the white deposit of calcareous tufa exposed
in a road cut near the mine (C.W. Jennings, 1964, oral
communication) .
References: Crawford, 1894, p. 392; Brodley, 1916, p. 206; Logon, 1947,
p. 248.
CENTRAL COAST RANGES REGION (B)
This region covers the central part of the Coast
Ranges and an adjacent portion of the Sacramento
Valley (plate IB). It includes all of Alameda, Marin,
Napa, San Francisco, Santa Clara, Santa Cruz, and
Sonoma Counties, and parts of Contra Costa, Merced,
Sacramento, San Joaquin, Solano, and Stanislaus
Counties. Although San Francisco Bay and its related
waterways physically subdivide the region, they also
serve as important harbors around which a large
population and attendant industries have become con-
centrated.
Topographically, San Francisco Bay is a drowned,
northwestern extension of the Santa Clara Valley.
The valley and bay are bordered on the west by the
Santa Cruz Mountains and on the east by the exten-
sive Diablo Range. The mountain and valley features
north of San Francisco Bay are less distinctive, having
many local names, but essentially constitute the south-
ern end of the northern Coast Ranges.
Limestone and shell deposits are abundant in the
San Francisco Bay area, and many of them have been
developed to serve regional and local markets. The
earliest commercial developments were for lime, be-
ginning about 1850 at the Olema deposit in Marin
County and in 1851 at theCowell Home Ranch depos-
its in Santa Cruz County. Some lime also may have
been produced in 1851 from the Lime Ridge deposits,
Contra Costa County. The first cement (hydraulic)
was produced in 1860 from limestone near Benicia,
Solano County. Portland cement was first manufac-
tured in 1902 at Cement, Solano County, and in 1903
at Napa Junction, Napa County. The strong demand
for lime coupled with excessive land transportation
costs were responsible for the opening of many small,
and often impure, deposits of limestone in the late
nineteenth and early twentieth centuries. A number
of deposits also were opened in the 1920s and early
1930s to meet the sudden expanded demand for agri-
cultural limestone. For additional historical data see
Bowen, 1951. More recently, a number of quarries
were established in cherty limestone to supply struc-
tural needs such as aggregate and road material. It is
emphasized here that many of the deposits, originally
operated as local sources of lime and structural and
agricultural materials, are no longer of economic in-
terest. Limestone of potential industrial value appears
to be limited to the crystalline limestone of Santa Cruz
County and the shells of San Francisco Bay. However,
with selective quarrying and beneficiation, the lime-
stone of the Franciscan Formation may also have in-
dustrial potential.
Geologically, the oldest limestone in the San Fran-
cisco Bay area is part of a metamorphic rock unit
similar to the Sur Series of the Santa Lucia Range to
the south. Most of the limestone is coarse crystalline
and high in calcium, although some is notably sili-
ceous and some is locally magnesian. Substantial but
undetermined limestone reserves exist in Santa Cruz
County, and small occurrences are known in Marin
and San Mateo Counties. Most of the lime manufac-
tured in the Bay area was made from the crystalline-
limestone of Santa Cruz County-
Even more widespread is the Cretaceous limestone
of the Franciscan Formation. Limestone of the Fran-
ciscan has been informally designated the Calera and
Laytonville types — the Calera-type being light to dark
gray and the Lavtonville-tvpe being pink to red (Bai-
ley era/., 1964, p. 68-77; Garrison and Bailey, 1967, p.
B94-B100). The former is much more common than
the latter. Both types of limestone are fine grained,
thin bedded and highly fossiliferous (Foraminifera,
nannoplankton). Large reserves of the Franciscan
limestone are available in San Mateo and Santa Clara
Counties and minor deposits are known in Marin,
Sonoma, and Alameda Counties. However, because
abundant thin interbeds and lenses of chert are almost
always present, most of the limestone deposits arc of
value solely as sources of crushed stone. The one great
exception is the Permanente deposit which, as a result
of selective quarrying and recent beneficiation, has
provided raw materials for a major cement plant since
1939. A few other limestone deposits may be large
enough to be amenable to beneficiation and conse-
quently may be of potential industrial value.
Quaternary carbonate deposits of two types have
also been of considerable importance. Deposits as-
sociated with springs have yielded large quantities of
travertine, calcareous tufa, and caliche for cement
2— S94S4
12
' California Division of Mines and Geology
Bull. 197
manufacture in Contra Costa and Solano Counties,
but reserves are largely depleted. Some of the surficial
carbonate deposits, however, may be of value for orna-
mental uses. Quaternary shell deposits are of greater
future value, with apparent large reserves existing in
southern San Francisco Bay. The shells are largely
associated with soft bay mud which is used with the
shells for cement manufacture* or is easily washed
from the shells used for various agricultural and in-
dustrial purposes. Similar but smaller shell deposits
may also exist in the other bays and estuaries of the
central region.
A variety of other limestone deposits, ranging in age
from Late Jurassic(?) to Pleistocene, have been used
or considered as sources of carbonate rock. Most of
these are too impure or too small to be of future inter-
est other than as local sources of crushed rock.
Total production of limestone and shells in the cen-
tral Coast Ranges region through 1968 is estimated to
be 145 million tons. About 80% was used for cement,
4% for lime, 1 to 2% for livestock feed and soil condi-
tioning, and the remainder for aggregate, riprap, road
base, and other construction purposes. The principal
production has come from the following counties, list-
ed in approximate order of decreasing production:
Santa Clara, Santa Cruz, San Mateo, Contra Costa,
Alameda, Solano, and Napa. Minor amounts of lime-
stone have also been produced in Marin, Sonoma, and
San Joaquin Counties.
The limestone deposits of the central Coast Ranges
region are shown on plate IB and are discussed below
in alphabetical order within each district. The dis-
tricts of the region are listed in geographic order from
north to south.
HEALDSBURG DISTRICT (B-l)
This district, which covers Sonoma County and
part of Napa County, is relatively unimportant as a
future limestone-producing area. Small amounts of
limestone were quarried intermittently as sources of
lime from the Black Ranch and Pope Valley deposits,
and from an unnamed deposit near Geyserville,
between 1880 and 1937. Other deposits remain un-
developed. The only recent activity is at Petaluma,
where shells, dredged from San Francisco Bay by Pio-
neer Shell Company, are processed for livestock and
agricultural uses (see San Francisco Bay Shell depos-
its under San Francisco Bay district).
Black Ranch deposit. Location: Approx. N'/2 sec.
!0, T. 1 1 N :., R. 9 W. (proj.), M.D., 5 miles north of
Geyserville; Kelseyville 1 5-minute quadrangle. Own-
ership: I lollis M. Black, 2822 5 River Road, Cloverdale
(1962).
This deposit has been worked intermittently as a
source of lime rock from 1884 to 1907 and again in
" Production of shells for cement manufacture ceased in late 1970. See foot-
notes under San Francisco Bay Shell deposits.
1937. According to Aubury ( 1906, p. 93 ) , "It was first
opened in 1884, and reopened in April, 1901" by the
Sonoma County Lime Company. The same company
worked the deposit again in 1906-1907. J. F. Bishop of
Santa Rosa apparently was the operator in 1937.
The Black Ranch deposit consists of a single bold
outcrop of limestone 150 feet long by a maximum of
70 feet wide with a relief of about 50 feet. It lies
between the dirt access road and a west tributary to
Little Sulphur Creek. The limestone projects from a
structurally disturbed terrain mainly consisting of
graywacke, chert, schist, greenstone, and other Fran-
ciscan-like rocks. Faint bedding(?) in the limestone
appears to dip steeply to the east. The limestone is fine
to medium crystalline, dense, brownish gray some-
times mottled with white, with no visible impurities.
Two typical grab-samples (BR-1 mottled with white)
were analyzed by Lydia Lofgren in 1962 and show the
following chemistry:
Ign.
Sample CaO MgO SiO_. MX), Fe,Q, P.O. loss
BR-1 55.00% 0.4!% 0.80% 0.12% 0.07% 0.04% 45.08%
BR-2 54.50 1.19 0.90 0.13 0.14 0.02 4}. 22
Development is limited to a small hillside quarry on
the north side of the deposit. Not more than a few
thousand tons of limestone were quarried, and this
was hauled 300 feet east to a vertical (continuous)
stone kiln of 50 barrels per day capacity. Reserves are
small; probably not more than 20,000 to 30,000 tons of
limestone.
Other references: lrelan(?), 1888, p. 633; Crawford, 1894, p. 396; Brad-
ley, 1916, p. 323; Logan, 1947, p. 333; Honke and Ver Planck, 1950, p. 95.
Healdsburg Marble Company deposit. Location:
NE'/4 sec. 2, T. 9 N., R. 12 W., M.D., 7 miles west-
southwest of Skaggs Springs and 15 miles west of
Healdsburg; Tombs Creek 7'/2-minute quadrangle.
Ownership: Not determined.
Many years ago, a company by this name located
claims on a fine-grained, "red, white, and cream col-
ored" limestone in sees. 1 and 2 (Bradley, 1916, p.
323 ). This undoubtedly is the same as, or includes, the
reddish Franciscan limestone at the southeast end of
Shoeheart Ridge in NE'/4 sec. 2. E. H. Bailey (oral
communication, 1962) reported the limestone to be
thin bedded and traceable for about 1,000 feet in a
westerly direction. It is sandwiched between green-
stone on the south and sandstone on the north. The
limestone sequence is about 7 feet thick in a tributary
to House Creek, but it is a little thicker to the west. No
chemical analyses are available, but the limestone may
be impure (Honke and Ver Planck, 1950, p. 95). Be-
cause of its inaccessibility and small reserves, the
deposit is undeveloped and does not seem to be of
economic interest.
Other reference: Logan, 1947, p. 333.
Kohlman (Coleman) Gulch deposit. Location:
Sec. 13, T. 8 N., R. 13 W., M.D., about 1'/, miles north
1978
LlMISTONI IN I II! COASI K W(,l S
13
of Fort Ross; Plantation T'/j-minute quadrangle. Own-
ership: Not determined.
"Extensive deposits of pulverulent limestone" were
noted bv Watts (1893, p. 463) in Coleman Gulch. Lo-
gan (1947, p. 334) corrected the spelling of "Coleman"
to "Kohlman" and stated that "only meager evidence
of limestone was found." Current topographic maps
now show the name of the stream to be Kolmer Gulch.
There is no development of the deposit.
Other reference: Honke and Ver Planck, 1950, p. 95.
Pioneer Shell Company. The company operates a
plant at 100 East "D" Street, Petaluma, where oyster
shells from San Francisco Bay are processed. (For
description see San Francisco Bay Shell deposits, San
Francisco Bay district.)
Pope Valley deposit. Location: Vicinity of sec.
32 (?), T. 10 N., R. 5 W., M.D., about 11 miles north
of St. Helena; St. Helena 1 5-minute quadrangle. Own-
ership: Not determined.
According to Crawford (1896, p. 629), lime was
made in two kilns in Pope Valley during the 1890s.
Reportedlv, onlv small quantities of lime were made
although "two kilns are in constant use". The source
of limestone is not known but could have been thin
beds or lenses of limestone that commonly occur in
the Knoxville Formation or overlying Lower Creta-
ceous rocks of Pope Valley. An old lime kiln in or near
sec. 32 (Dow and Thayer, 1946, p. 23) may relate to
the above. Knoxville and associated strata are exposed
along the north margin of Pope Valley and near sec.
32.
Other reference: Bradley, 1916, p. 271.
Purviance Ranch deposit. Location: Possibly sec.
23 or 24, T. 9 N., R. 10 W., M.D.; Healdsburg 15-
minute quadrangle. Ownership: Not determined.
Small outcrops of limestone have been reported 3'/z
miles west of Healdsburg on the Purviance Ranch.
Apparently there is no development of this deposit,
although C. A. Perry had an option on it (Laizure,
1926, p. 336). The deposit was not located during the
present study. A chemical analysis of the limestone,
made in 1906 by Thomas Price and Son, is partially as
follows: 93.45% CaC03, 1.22% MgC03, 1.13%
FeC03, 1.96% A1203, and 1.59% Si02. The limestone
lies in an area underlain by the Franciscan Formation.
Other references: Logan, 1947, p. 334; Honke and Ver Planck, 1950, p.
95.
Unnamed deposit (near Geyserville) . Location:
Near E1/, cor. sec. 14, T. 10 N., R. 9 W., M.D., 4'/2 miles
east of Gevserville; Healdsburg 1 5-minute quadran-
gle. Ownership: Not determined.
This deposit is developed near an old marble quarry
and kiln. It is described by Gealey (1951, p. 46, plate
1): " The marble is gray and finely crystalline, but in
scattered patches some calcite crystals reach a length
of as much as 2 inches. The material is in metamor-
phosed Franciscan limestone. Lime was first burned
here about 1880. The body is far too small to be of
economic importance today." The deposit may be the
same one referred to by Irelan ( 1888, p. 633) or Craw-
ford (1894, p. 396).
NORTH BAY DISTRICT (B-2)
This district includes all of the deposits in Marin
and Solano Counties and one deposit in southern
Napa County (plate 1 B) . Not only have these deposits
contributed substantially to the early economy of the
San Francisco Bay area, they have also contributed
richly to its history. Possibly the first limes'one depos-
it worked commercially in the Coast Ranges of Cali-
fornia is the tiny Olema deposit, operated about
1850-1852. The Inverness Park and Cement Hill
deposits also were very early sources of lime rock.
About 1860, California's first hydraulic cement plant
was established at Benicia. It used shells or impure
limestone from local deposits until it was shut down
around 1890. One of the earliest Portland cement
plants in California was established at the Cement
Hill deposit in 1902. Here, travertine was quarried as
the principal raw material. The next year, impure
shelly limestone was developed as a source of cement
rock at the Napa Junction deposits. Some of these
deposits, along with the Tolenas Springs deposit, also
yielded limestone for terrazzo, decorative stone, and
flux.
Only the Tolenas Springs deposit is now active. It
presently is operated on a small scale, yielding traver-
tine and onyx marble for terrazzo.
The deposits are geologically varied, consisting of
crystalline limestone of pre-Cretaceous age, dense
limestone of the Franciscan Formation, impure lime-
stone (both fine grained and bioclastic) of late Meso-
zoic and early Tertiary age, and shell and surficial
carbonate deposits of (Quaternary age.
The deposits of the North Bay district seem to offer
little significant commercial potential, except for
deposits useful as a source of decorative and crushed
rock. Late Quaternary shell accumulations, such as
that found in Tomales Bay (see Tomales Bay shell
deposit) may provide additional economic possibili-
ties.
Bender deposit. Location: Approx. sec. 21, T. 3
N., R. 9 W. (proj.), M.I), 1 mile south-southeast of
Inverness, Marin County; Point Reyes 1 5-minute
quadrangle. Ownership: E. A. Bender, Inverness
(1962).
Several small bodies of crystalline limestone as-
sociated with biotite schist and intruded by quart/
diorite are reported by the owner to occur in a small
canyon that drains the northeast flank of Point Reyes
Hill The limestone is situated '/2 to '/ of a mile inland
from Willow Point on Tomales Bay. It is similar to the
metamorphosed Sur Series limestone of the southern
Coast Ranges, being coarse crystalline, white, and
sparsely flecked with graphite flakes. Scheelite crys-
tals up to half an inch occur in the limestone, which
14
California Division of Mines and Geology
Bull 1976
stimulated tungsten exploration in the early 1950s
(Yer Planck, 1955, p. 260, 265-266). According to the
owner, none of the limestone bodies shows a thickness
of more than 25 feet. Because of small reserves and its
intimate association with schist and granitic rock, the
limestone is not believed to be of economic interest.
Benicia Cement Works deposit. Location: Proba-
bly SE'/4 sec. 34, T. 3 N., R. 3 W., M.D., in Benicia;
Benicia 7'/2-minute quadrangle. Ownership: Not de-
termined.
California's first cement plant was established at
Benicia about 1860 to manufacture "hydraulic" ce-
ment. The cement works, which had a productive
capacity of about 100 barrels of cement per day, was
operated intermittently and produced only modest
amounts of cement. After approximately 30 years of
intermittent production, the works was abandoned.
Total production of cement is not recorded in the
literature although Williams (1885, p. 675) reports the
largest production was in 1872, when 25,500 barrels of
cement were made. The cement was used in various
construction projects, including a seawall in San Fran-
cisco Harbor and the San Francisco City Hall, and in
the manufacture of drainage and water pipe. Rem-
nants of an old kiln along the Benicia waterfront south
of EyeStreet between 8th and 9th Streets still exist and
very likely are the remains of the Benicia Cement
Works.
The source of "hydraulic" limestone seems uncer-
tain, and there may have been more than one quarry
area or deposit. The limestone source has been vari-
ously reported to be in the hills behind Benicia (Whit-
ney, 1865, p. 101; Browne, 1868, p. 245), 1 mile south
of \ allejo (Williams, 1883, p. 463), and in sec. 33 with-
in the Benicia town limits (Aubury, 1906, p. 185). The
nature of the raw material also is unclear. Whitney
( 1865, p. 101) states that the "hydraulic limestone" is
associated with "beds of passage" between "sand-
stones and shales" (veins filling a fault or fracture?).
A description of the material is given by Browne
(1868, p. 245) who reports two grades of hydraulic
limestone which he describes as being "of a dark yel-
lowish color, speckled with black, tolerably soft;
breaks with a dull, earthy fracture, without any ap-
pearance of crystallization." Exactly what rock type
or units are represented has not been determined. The
principal carbonate materials found near the old kiln
are part of an upper Pleistocene marine unit (Weaver,
1949, p. 52). Along the waterfront, in a cove northwest
of the kiln, this unit consists mainly of bedded mud,
shells, and sand of estuarine origin. Five to ten feet of
the unit are composed principally of oyster shells
similar to Ostrea luridj Carpenter. This is overlain by
about 20 feet of mudstone with occasional shelly
streaks. About 5 feet of impure carbonate beds of vari-
able character (shells, sand, mud, and possibly second-
ary calcite) and uncertain origin overlie the mudstone
(Oliver E. Bowen, 1964, oral communication). Al-
though these carbonate rocks would seem to be the
logical source for the Benicia cement, Whitney refers
to the oyster beds (1865, p. 102) but does not relate
them to cement manufacture. Another possible source
is indicated by calcareous shale and argillaceous lime-
stone fragments found in and about the kiln (Oliver
E. Bowen, 1964, oral communication). Similar materi-
al commonly occurs in the Paleocene and Cretaceous
units exposed in the vicinity of Benicia.
Other references: Irelan, 1888, p. 632; Crawford, 1894, p. 381; Logon,
1947, p. 333.
Cement Hill deposits. Location: Sees. 5, 7, and 8;
T. 5 N., R. 1 W., M.D., 3 to 4 miles northeast of Fair-
field; Mount Vaca and Yacaville 15-minute quadran-
gles. Ownership: Mineral rights — Ideal Cement Com-
pany, 420 Ideal Cement Building, Denver, Colorado
80202; surface rights— E.N. Tooby, Fairfield (1962).
Travertine and related surficial carbonate deposits
on Cement Hill were first developed prior to 1865 for
use as lime rock and ornamental stone (Whitney, 1865,
p. 104) . The rock was extensively used as an ornamen-
tal material known as "Suisun marble". As a lime
rock, the travertine was burned in a vertical kiln locat-
ed just south of E'/4 cor. sec. 7. Remains of the kiln still
stand. For some years prior to 1900, the travertine was
also obtained from Dicky's quarry for use as flux at
ASARCO's Selby smelter (Crawford, 1894, p. 395).
Some macadam also was produced. Probably the bulk
of the carbonate rock produced was used to manufac-
ture portland cement.
The first cement mill was constructed by Pacific
Portland Cement Company (predecessor to Ideal Ce-
ment Company) in 1902 at the foot of Cement Hill,
700 feet north of SW cor. sec. 8. The plant was expand-
ed in 1903 and 1905, reaching a capacity of 2,500 bar-
rels of cement per day (Bradley, 1916, p. 303).
According to Huguenin and Costello (1920, p. 243),
this plant was "completely wrecked" shortly before
1920. In 1907, another cement mill was constructed
2,000 feet to the southeast in sec. 17. Capacity of the
second mill was 3,500 barrels per day. Prior to 1910,
the carbonate raw material came from the Cement
Hill deposits. After 1910, however, most of the lime-
stone was imported by rail from Cool, El Dorado
County. The cement plant was closed and dismantled
in 1927.
Following the cement operation, travertine from
Cement Hill was quarried intermittently for orna-
mental and terrazzo uses. P. Grassi and Company
(1927, 1935-36) and United Quarries, Inc., (1939^2)
were the operators. It is reported that Kasser (?) and
Ball and the Morrison-Knudsen Company quarried
large amounts of travertine and underlying sandstone
in the early 1940s to construct airstrips at Travis Air
Force Base.
The Cement Hill deposits consist of travertine, cal-
careous tufa, and related calcareous materials. The
carbonate rocks form numerous surficial deposits on
1978
I s I l\ I III COASI R \\(U S
15
the west, south, and southeast sides of the hill. The
deposits probably formed from spring water during
Quaternary time, although only a few small springs
were noted in the area. However, brecciated sand-
stone and conglomerate (Domengine and Chico For-
mations, Weaver, 1949) cemented with travertine
suggest that fault-associated springs may have been
more prevalent in the past. Travertine is the principal
carbonate material remaining, although little can be
said of the nature of the material quarried.
Much of the travertine in the quarry areas is me-
dium to coarse crystalline, fairly dense, distinctly
banded, and nearly white to yellowish brown. It ap-
pears to have formed mainly as near-surface fracture
fillings. Elsewhere, particularly in SE'/4 sec. 8, the
travertine is fine crystalline, usually amber to honey
brown, thinly banded, and somewhat porous (vuggy).
This variety seems to form at the ground surface. As-
sociated with the travertine are other carbonate
materials, including the softer calcareous tufa and
caliche, which appear to be somewhat impure. Analy-
ses of the pure travertine (Eckel, 1913, p. 121) show
that the material consists mainly of calcium carbonate.
Some is also associated with brecciated sandstone and
conglomerate. The deposit is a sort of stockwork,
grading downward from relatively pure travertine
into fractured country rocks having vein fillings of
calcium carbonate (Goodyear, 1890, p. 670).
Reserves of carbonate rock are difficult to estimate
because deposits are scattered over sec. 8 and adjacent
parts of sec. 7 and S\V'/4SVV'/4 sec. 5. The largest depos-
it probably was the one located just south of NW cor.
sec. 8, where it covers an area 1,700 by "00 feet. A
hillside quarrv 1,100 by 700 feet with a maximum face
of 200 feet has nearly exhausted the deposit. Judging
from the depth of the quarry (visited April 1962), it
is estimated that the deposit was at least 60 to 70 feet
in maximum thickness. In S1/, sec. 8 another extensive
deposit covers a triangular area half a mile long by a
maximum of 1,800 feet wide. Sandstone exposed in a
series of broad, shallow benchcuts indicates the traver-
tine to be no more than 15 to 20 feet thick. This area
was worked most recently, probably for construction
materials used at Travis Air Force Base.
A number of smaller deposits, some undeveloped,
lie on the southeast, southwest, and west slopes of
Cement Hill. The most impressive of these is a thin,
narrow body several hundred feet long situated 1,200
feet east-southeast of center sec. 8. Thinly banded,
yellowish-brown, fine-grained, vuggy travertine of
rather pleasing appearance constitutes the deposit.
Such material may be useful as terrazzo and for other
ornamental purposes. Reserves may be in the order of
10,000 tons. Larger reserves exist elsewhere on Ce-
ment Hill, but the travertine does not appear to have
as much ornamental value.
Other references: Browne, 1868, p 243, Wotts, 1890, p 669 and 1893,
p. 191; Aubury. 1906, p. 108, 185-189; Laizure, 1927, p. 205-208, 210;
Logon, 1947, p. 332; Weover, 1949, p. 88, pi. 5, 7.
Deniing's Point deposit. Location: Approx. sec.
16, T. 3 N., R. 3 W., M.D., 2 miles east of Vallejo;
Benicia 7'/2-minute quadrangle. Ownership: Not de-
termined.
"A large outcrop of rock suitable for making ce-
ment" is reported by Crawford (1894, p. 381). There
has been no known development. The area is under-
lain by the Chico Formation of Late Cretaceous age
(Weaver, 1949, plate 15).
Inverness Park (Lockhart Tract, Point Reyes,
Tomales Bay, Trout Farm) deposits. Location:
Near SE'/4 sec. 34, T. 3 N., R. 9 W. (proj.), M.D., V/2
miles west of Point Reyes Station; Point Reyes 15-
minute quadrangle. Ownership: J. W. Lockhart, In-
verness Park (1962).
Coarse-crystalline, white to brown-stained lime-
stone similar to the Sur Series limestone is exposed as
scattered outcrops on the Lockhart Ranch near
Drakes Summit Road, 3,000 feet west of Inverness
Park. Reportedly, the limestone can be traced by
means of detached outcrops and float for nearly half
a mile northwest to a point not more than 200 yards
southeast of Drakes Summit (Yer Planck, 1955, p.
2 59). The presence of granitic soil between the de-
tached outcrops strongly indicates that the deposit
consists of small discontinuous masses of limestone
According to Alan J. Galloway (unpublished report),
the limestone covers an area of about 30 acres and the
largest exposure is about 40 feet long by 20 feet high.
Additional limestone is exposed in Haggerty Gulch
about a quarter mile to the east of the summit expo-
sures. Here, coarse-crystalline white limestone is in-
terbedded with schist and cut by dikes of pegmatite
and quart/, diorite.
A number of limestone samples have been collected
and analyzed over the years and these are listed in
table 2. Samples 1-6 probably indicate the best grade
of limestone available. Some of the limestone, howev-
er, is locally siliceous or iron stained (sample 7).
The Inverness Park deposits were developed in a
limited way many years ago. A small quarry and sev-
eral test pits are situated just northwest of Drakes
Summit Road on the Lockhart property. Another
quarrv is reported at the "Trout Farm" locality (Eck-
el, 1933, p. 353) which is believed to be in the canyon
at the north end of the deposits. Apparently the lime-
stone was used mainly as a source of lime. I wo small
kilns are reported by Yer Planck (1955, p. 259) close
to Drakes Summit Road within 100 yards of Sir Fran-
cis Drake Highway. These kilns apparently were op-
erated at least as early as 1856 (Galloway, unpublished
report) and were last used around the turn of the
century (Eckel, 1933, p. 353). Production was small,
although no official records exist. Potential of the
limestone near Inverness Park seems quite limited, as
limestone reserves appear to be small and distributed
among a number of small, scattered bodies.
Other references: Anderson, 1899, p. 131; Logon, 1947, p. 251; Weover,
1949, p 88, plole 9; Gollowoy, 1962, p. 396. plole 26.
16
California Division of Mines and Geology
Bull. 197
Table 2. Chemical analyses of limestone from Marin County.
Sim- Ign
pk SiO. AW, Fe.O, 00 OCO, MgO MgCO, P.O. loss
limestone could not be determined although Weaver
(1949, plate IS) shows it to be part of the Eocene
Domengine Formation. In contrast, however, Weaver
indicates similar limestone half a mile to the south to
be part of an undivided sequence of Late Jurassic or
Early Cretaceous age.
At the south deposit the carbonate rocks are similar
to those of the main area, but they may be less pure
and finer grained. Certainly the south exposures are
less extensive, covering a low rise perhaps 300 to 400
feet in diameter. The rocks are not well bedded here
although one bed showed a dip of 70° W. A third and
even smaller outcrop is exposed in a small pit 1,000
feet northwest of the main outcrop.
Because the limestone of the three areas show com-
mon characteristics, they are no doubt of common
origin and probably of the same formation. However,
the deposits probably are not contiguous, as there is
evidence of faulting and brecciation in the main and
south areas.
Chemical analyses of the limestone were made
many years ago and are shown in table 3. According
to Eckel (1913, p. 121-122), the deposit contained two
grades of limestone that ran 60 to 65% and 85 to 90%
calcium carbonate. It is obvious that very little "high-
grade" limestone remains in the deposit although low-
grade limestone and related calcareous beds may be
extensive, particularly in the main area. Reserves are
not known; but, even if large, the deposit appears to
be too impure for cement manufacture and other uses.
Most of the reserves are expected to be north of and
down dip from the main quarry area.
Table 3. Chemical analyses of limestone from Napa Junction
deposits, Napa County (from Eckel, 1913, p. 122).
Sample SiO: AI.O, Fe:Q, CiCO, MgCO,
High-lime rock
No. 1 66}% 3.61% 1.26% 85.17% 1.83%
No. 2 7.12 2.36 1.16 87.70 0.84
Low-lime rock
No. 1 20.87 10.50 3.50 62.76 1.48
No. 2 20.23 8.68 3.1 1 65.23 1.72
Development of the limestone was mainly near the
E1/ cor. sec. 24 along the north side of the ridge where
three linear pits extend continuously over an area 1,-
700 feet by 200 to 400 feet. Excavation apparently ex-
tended deeper than the present pit, which is as deep
as 40 feet and has been partly filled with debris and
slope wash. Smaller pits lie west and north of the main
quarries. In the south area, the pit is about 200 by 300
feet in area and is more than 25 feet deep. Most of the
pits were worked below the water table and contain
ponded water. Based on the observable sizes of the pits
(April 1962), it is estimated that at least 1.5 million
tons of limestone and associated clay was produced
during the 15 years of operation. The raw materials
were hauled in small dump cars by rail to the cement
mill located immediately north of the main quarry.
1 66%
0.44%
020%
v n
96.60%
YD.
0.7!%
N D
ND
2.26
0.55
0.25
ND
95.48
ND
1.10
ND.
ND
1
2.23
0.76
incl
?! 80%
96.00
0.35%
ND.
ND.
4270%
1
no
0 JO
incl
54.32
97.00
1.25
ND
ND.
42.68
i
1.98
0.12
0.09
53.9!
ND
0.38
ND
■0.0)%
N.D.
6
2.65
139
0 34
53.50
ND
0.8!
YD.
0.07
42.20
"
10.81
j
1.61
43.25
ND
0.80
ND
0.21
ND
I
Ltd
0.68
incl
54.80
97.80
ND
tr
ND
4)20
)
1.90
0.76
0.20
ND
96.74
0.i!
ND
ND.
ND.
10
0.51
Oil
53.89
ND
018
ND
0.07
ND
II
1.69
022
0.40
54.15
ND
0.29
ND.
0.14
ND.
N.D. = Not determined
incl. = included with AI.O,
tr. - trace
Samples l-~ are crystalline limestone similar to the Sur Series of Monterey
County.
Sample 1 from old quarry near "Trout Farm" (North of Lockhart Ranch).
Samples 2-3 and 5-7 from Lockhart Ranch
Sample 4 from near Inverness Park.
Samples K-ll are Franciscan Formation limestone from Olema deposit
Analyses 1-4 and 8-9 published in Eckel ( 193 3, tables 1 and 2)
Analyses 5-6 and 10-11 made by Abbot A Hanks, Inc., 1956.
Analysis 7 made by Lydia Lofgren, Calif. Division of Mines and Geologv,
1962.
Napa Junction deposits. Location: Es/2 sec. 24, T.
4 N., R. 4 W., and W'/ sec. 19, T. 4 N., R. 3 W., M.D.,
1 mile south of Napa Junction and 5 miles north of
Vallejo; Cordelia 7'/2-minute quadrangle. Ownership:
Principally Basalt Rock Company, 8th and River
Streets, Napa ( 1962).
Impure limestone and associated clay were used to
make cement from 1903 to 1918 by Standard Portland
Cement Company. The company reportedly ceased
operation of their Napa Junction plant in September
1918, apparently because most of the better quality
limestone was used up. The Napa Junction deposits
are not known to have been worked since 1918.
The limestone is exposed as low outcrops in two
areas separated by alluvium. The north, or main,
deposit occupies a low, west-plunging ridge on which
are located a series of elongate pits. Because of thick
soil, exposures are limited mainly to the steep faces of
the pits. Here, the deposit consists of 50 to 100 feet of
crudely bedded, bioclastic limestone and related im-
pure carbonate rocks that strike about N 75° E and dip
;n N. Underlying the clastic beds at the base of the
exposed south face of the largest pit are beds of shale
with small lenses and concretions of fine-grained,
blue-black, impure limestone. It seems apparent that
the upper beds served as the principal source of lime-
stone and clay. These range in composition from near-
ly pure bioclastic limestone, with only scattered
noncarbonate fragments, to a fossiliferous mudstone
containing large amounts of mudstone (tuffaceous?)
pebbles and fossil debris. Color of the rocks varies
from greenish gray to yellowish brown and grain size
ranges from fine sand to gravel. Most of the carbonate
material appears to be shell and algal debris — proba-
bly derived from a near-shore reef. The age of the
1978
LlMFSTONK IN I III COASI R\N(ilS
17
There is some indication that high-grade limestone
from Santa Cruz was used to "sweeten" the raw
material mix. The cement mill utilized the dry
method, employing two large rotary kilns and 10 small
rOtary kilns with a total capacity of 2,500 barrels of
cement per day.
Other references: Bradley, 1916, p. 262-268; Huguenin and Costello,
1920, p. 1S8; Eckel, 1933, p. 359-360.
Noren deposit. Location: Near S'/, sec. 35, T. 3 N.,
R. 9 W. (proj.), M.D., 1 mile southwest of Point Reyes
Station; Point Reyes 15-minute quadrangle. Owner-
ship: C. R. N'oren, Inverness Park (1962).
A small pendant of metamorphic rock in quart/,
diorite is situated 1,000 feet south of the intersection
of Sir Francis Drake Highway and Bear Valley Road.
The pendant consists of coarse-crystalline, white to
brown (stained?) limestone and fine-crystalline, gray
limestone interbedded with biotite schist similar to
that of the Sur Series. The gray limestone is silicified
and locally replaced by scheelite, which was prospect-
ed to some extent in 1952 (Ver Planck, 1955, p. 260,
266). Another small pendant of limestone is reported
halt a mile to the southwest in the same creek. From
what was seen (April 1962) and reported, the Noren
deposit appears to be too small and impure to be of
commercial value as a source of limestone.
Olema ("Russian Kilns") deposit. Location: Ap-
prox. sec. 28, T. 2 N., R. 8 W. (proj.), M.D., 4 miles
southeast of Olema and 6 miles southeast of Point
Reyes Station; Mount Tamalpais 15-minute quadran-
gle. Ownership: Sam Smoot, Petaluma (1955).
The Olema limestone deposit was first developed
about 1850 as a source of lime rock. Lime was calcined
in three adjacent kilns. According to Treganza (1951,
p. 69), the lime kilns probably were operated last in
1852, although it is possible lime could have been
burned as late as 1869. Production is believed to have
been minor, as no large quarry exists at the deposit.
The kilns, which are located on the east bank of Olema
Creek immediately below the limestone exposure,
were previously believed to have been built and used
by the Russians at an early date. However, this theory
is fairly well disproved by Treganza ( 195 1 ), who stud-
ied the kilns in detail.
The limestone is confined to a single outcrop about
50 feet wide, 100 to 125 feet long, and 40 to 50 feet high.
Approximately 50 feet of strata are present, and these
strike X 60° W and dip 55° SW. The deposit consists
of thin-bedded Franciscan limestone and minor in-
terbedded chert, which is associated with other Fran-
ciscan rocks along the San Andreas fault zone. The
limestone typically is light tannish gray, dense, fine
grained, and foraminiferal. Chemistry of the lime-
stone is indicated by analyses of samples 8 to 11 in
Table 2.
Because no limestone is visible beyond the exposed
deposit, it is presumed the limestone deposit is a fault
sliver that does not extend much beyond the outcrop
area. Some fragments of similar limestone are report-
ed from two areas 1,000 feet and 2 miles to the south-
east in the fault zone (Galloway, unpublished report).
At the latter locality there are remnants of another old
kiln. Reserves of limestone at the Olema deposit are
estimated to be in the order of 10,000 to 15,000 tons.
Other references: logon, 1947, p. 251; Ver Plonck, 1955, p. 261; Gallo-
woy, 1962, p. 395, 398.
Tolenas Springs (California Onyx Marble) depos-
its. Location: W'/2 sec. 2 (proj.), T. 5 N., R. 2 W.,
M.D., 4 miles north of Fairfield; Mount Vaca 15-
minute quadrangle. Ownership: Woods Fstate Ranch
(1962); operated by Tolenas Quarry Company, 537
Cottonwood Drive, Fairfield (1969).
I ravertineand calcareous onyx have been known at
Tolenas Springs at least since 1878, when specimens
were displayed at the Paris Exhibition. Exactly when
the deposits were first worked commercially is not
known, but it may have been about the same time
(Hanks, 1884, p. 72; Goodyear, 1890, p. 670). The
deposits have been worked intermittently on a small
scale as a source of ornamental stone and terrazzo
materials. The early operators are not known; but the
later developers include S. Miletin ( 1926 and earlier?),
P. Grassi and Company and L. Cardini (1928-1936),
and Ray McRoberts and Paul Lahmon of Tolenas
Quarry Company (since about 1960). 'Total produc-
tion is believed to be several thousand tons.
Several small deposits of travertine and onyx lie in
the vicinity of 'Tolenas Springs in NW/4 sec. 2 (proj.) .
These rest on sandstone — apparently of the Chico
Formation. 'The main deposit is situated at the east
end of the group on the south bank of Soda Springs
Creek. It covers an area about 400-by-200 feet and may
have been 25 feet thick or thicker at one time (Good-
year, 1890, p. 671). The travertine is typically fine
grained, tan or brownish, thinly banded, and some-
what porous. The calcareous onyx is microcrvstalline
to finely fibrous, milky white to pale amber, translu-
cent, semiresinous to waxy, delicately banded, and
dense but commonly cavernous (vuggy). The onyx
occurs as lenses and irregular fracture fillings in the
travertine. Both materials are somewhat fractured and
are obtained in small pieces. Similar, but smaller,
spring deposits can be traced to the southwest for a
quarter of a mile. Another deposit 200 yards to the
northwest of the main deposit is shown by Weaver
(1949, plate 5), but nothing is known of this.
Development has been sporadic and limited princi-
pally to the main deposit. Recent (1962) workings
consist of a quarry face 1 5 feet high and 100 to 1 50 feet
long. By April 1967, small amounts of onyx or traver-
tine had also been produced from pits a quarter of a
mile southwest of the main quarry (Oliver F. Bowen,
personal communication, 1967). To the west and
southwest are two small old quarries, one of which is
about 30-by-30 feet with a 10-foot face. In 1962, the
IS
California Division of Mines and Geology
Bull. 197
carbonate material was selectively mined, crushed,
screened, and sold as terrazzo under the names
"Golden Travertino" (travertine) and "California
Onyx". Reserves of the two materials are not known
although the travertine appears to be more abundant
than the onyx.
Other references: Watts, 1890, p. 668; Waring, 1915, p. 162-163, 165;
Laizure, 1927, p. 210; Logan, 1947, p. 332.
Tomales Bay Shell deposit. Location: Approx.
sec. 5 (proj.), T. 3 N., R. 9 W., M.D., 2 miles north-
northwest of Inverness; Inverness 15-minute quadran-
gle. Ownership: Not determined.
This undeveloped shell deposit is described here to
demonstrate that sizable accumulations of shells exist
in coastal bays other than San Francisco Bay (see un-
der San Francisco Bay district) and that different ex-
ploration methods can be used in combination to
delineate submerged shell deposits.
According to C. C. Daetwyler (unpublished report,
1965, p. 56, 184), a shoal area on the northeast side of
Tomales Bay is covered with Holocene shells and as-
sociated mud at least 7.8 feet thick. The shells are
shown to cover an irregular area of more than 100
acres with maximum dimensions of about 4000-by-
2000 feet. By combining an acoustic-reflection survey
(Sonoprobe) with shallow cores and test borings, Da-
etwyler (p. 48, 56, 67, 75, 184) was able to determine
the surface distribution of the shell accumulation. A
description of test boring No. 13 (Daetwyler, p. 184),
made in 13 feet of water east of Pebble Beach, shows
shells (predominantly Ostrea lurida Carpenter) in a
silt and clay matrix, with scattered pebbles and angu-
lar quartz grains to a depth of 7.8 feet below the
present bay bottom. Although 5 to 30% shells are in-
dicated to be present on the bay bottom (Daetwyler,
p. 56), the average thickness and percentage of shells
present for the entire deposit is unknown. Based on
this limited information, roughly 100,000 to 500,000
tons of shell are believed to be present in this shallow
deposit.
Using similar exploration methods, Daetwyler (p.
112, 180) also found other shell deposits 1 to 2 miles
to the northwest at the base of an older bay mud se-
quence. Because these older deposits are small and
covered by .34 feet of mud, they are not of commercial
interest. However, the younger shell deposit may be
of economic value because of its shallow depth and the
low cost of dredging and washing. On the other hand,
various other economic and political factors may tend
to conflict with dredging activities.
Other reference: Eckel, 1933, p. 359.
SAN FRANCISCO BAY DISTRICT (B-3)
This district encompasses the deposits in and about
San Francisco Bay in Alameda, Contra Costa, San
Francisco, and San Mateo Counties and adjacent parts
of San Joaquin and Santa Clara Counties. There is a
wide variety of limestone and shell deposits in the
district, but no dolomite is known. Because the district
encompasses a highly populated and industrialized
area, virtually all carbonate occurrences have been
examined; and many, including some very small or
impure ones, have been worked as sources of lime-
stone.
As many as 14 or 15 deposits have been worked for
limestone and shells beginning about 1851. Since then,
large amounts of limestone and shells have been pro-
duced for cement (San Francisco Bay Shell deposits,
Lime Ridge deposits) and for crushed rock uses
(Rockaway deposits. Skyline deposits). Limestone
and shells have also been used for a variety of other
purposes, including lime manufacture, livestock feed,
soil conditioning, and decorative uses. In 1968, the San
Francisco Bay Shell deposits and the Rockaway depos-
its were still being used extensively as sources for
cement, crushed rock, livestock feed, and soil condi-
tioning.
The carbonate materials are widely distributed in
the San Francisco Bay district in a variety of forms.
Most important, in terms of both past and future re-
sources, are the shell deposits of southern San Fran-
cisco Bay and the thin-bedded chert-associated
Cretaceous limestone of the Franciscan Formation in
San Mateo County.
The shell deposits, which are largely associated
with soft bay mud, reflect population explosions of the
native oyster, Ostrea lurida Carpenter, during Holo-
cene time. Although impure, these deposits contain
extensive reserves at a shallow depth and are easy to
dredge. Other deposits may exist outside of the south-
ern arm of the bay, but none of commercial value is
known.
The thin-bedded limestone of the Franciscan For-
mation— commonly referred to as Calera limestone —
is also important. Deposits of this relatively impure
limestone (usually 20 to 50% chert) are distributed
discontinuously along a narrow belt for 11 miles
southeast of Rockaway in Pacifica (Walker, 1950b;
Darrow, 1963, plate 1). Of at least nine quarries, Rock-
away was the only active deposit in 1968. Unless the
deposits can be beneficiated, future development will
depend on construction and other crushed rock needs.
Quaternary deposits of travertine, calcareous tufa,
and other surficial materials have been important in
the past (Lime Ridge deposits) but only relatively
small reserves remain. Other limestone deposits of
pre-Cretaceous to Quaternary age are either too small
or too impure to be of future commercial use, except
as local sources of crushed rock.
Cahill Ridge deposits. Location: Sees. 2 and 3, T.
5 S., R. 5 W., and sees. 3 3 and 34, T. 4 S., R. 5 W., M.D.,
4 miles southwest of San Mateo; Montara Mountain
7'/2-mimjte quadrangle. Ownership: City and County
of San Francisco Water Department (1962).
1978
I I M I SIMM |\ I III C().\SI R S
19
Limestone of the Franciscan Formation is shown as
four discontinuous masses extending more than 2
miles northwesterly from SW'XSW1/, sec. 2 by Walker
( 1950b, plate 1 ). The deposits, which lie on the steep,
vegetated slopes of Cahill Ridge, are of difficult access
except at the southeast end. There, typically light-
gray, fine-grained, dense, high-calcium limestone, as-
sociated with thin-bedded chert, is exposed as occa-
sional low outcrops; and there is abundant angular
float over an area 400 feet by at least 800 feet. The
northwest extent of this mass is obscured by dense
vegetation, and limestone reserves could be large. Re-
serves, estimated solely for the exposed area of the
limestone mass, are substantial, amounting to about
20,000 tons of limestone and associated chert per foot
of depth.
Because the deposits on Cahill Ridge lie within the
drainage area of potable water supplies of San Fran-
cisco, development possibilities probably are limited.
Nonetheless, the Cahill Ridge deposits may represent
important limestone reserves and warrant additional
investigation. 'This view is also supported by Walker
(1950b, p. 7-8). The deposits are undeveloped and
probably unexplored.
California Aggregates (Royce) deposits. Loca-
tion: Sec. 1 1, T. 4 S., R. 6 W. (proj ), M.D., in Pacifica,
mile south-southeast of Rockaway Beach settle-
ment; San Mateo 15-minute quadrangle. Ownership:
Ken Royce, Inc., 205 S. Linden Avenue, South San
Francisco (1955).
Franciscan limestone and interbedded chert are ex-
posed in two quarry areas at the crest of the ridge
between Rockaway Beach and Pedro Valley. Accord-
ing to Darrow (1963, p. 12 and plate 2 ) , the limestone
occurs as two northwest-trending bodies — each about
700 feet long — which are part of a synclinal sequence
of basalt, chert, and other Franciscan rocks. However,
the bodies are broken by faulting and show considera-
ble variations in bedding attitudes. At the lower
(northwest) quarry, the limestone is mainly dark blue-
gray, fine crystalline, dense, thinly bedded, and in-
terbedded with some chert. Some northeast dips can
be seen in the north face of the quarry, but most of the
beds are crushed and disoriented. At the upper (south-
east) quarry, the limestone is light and dark gray and
occurs in thin sequences with chert and basalt. The
light-gray to dove-gray limestone is dense, fine
grained, and foraminiferal. The deposit apparently is
cut by a northwest-trending fault, as beds on either
side differ significantly in attitude.
Only two chemical analyses are available for these
deposits. An analysis presented by Walker (1950b, p.
7, table 2) shows 32.23% silica for the quarry-run
material and reflects the large amount of chert present
with the limestone. The other analysis (Logan, 1947,
p. 308) shows 91.7% CaCO, and 5.1% Si02 for the
blue limestone.
The deposits were worked as a source of crushed
rock used for road base and concrete aggregate from
1944 to 1952 (Davis, 1955, p. 435-436; Logan, 1947, p.
308). The lower quarry is developed as a trench
roughly 1,000 feet by 40 feet with a maximum depth
of 60 feet. The upper quarry is 400 to 500 feet in
diameter and 65 feet in maximum relief The west end
of the quarry is now used to support a large steel water
tank. According to Davis (p. 46), both pits apparently
were "mined to their economic limits". Based on quar-
ry sizes, it is estimated that roughly half a million tons
of rock were excavated. Limestone reserves are not
determinable but probably are small. As chert is so
prevalent in the limestone, future development of the
deposits appears to be limited to crushed rock uses.
Carnegie deposit. Location: SE'X sec. 33 and SW1/
sec. 34, T. 3 S., R. 4 E., M.D., '/2 mile south of Corral
1 follow Road at Carnegie (site) and 9 miles southwest
of Tracy; Altamont 7'/2-minute quadrangle. Owner-
ship: Not determined (1962).
The Carnegie deposit consists of several small vein
deposits formed during Quaternary time along the
Tesla fault zone. The fault separates Franciscan rocks
on the south from the Panoche Formation (Upper
Cretaceous) on the north (Huey, 1948, p. 62 and plate
2). According to Aubury (1906, p. 79), the main
deposit consists of a "series of aragonite veins" 3
inches to 3 feet wide which dip 65° NE. The hanging
wall consists of crushed shales although "considerable
serpentine inclusions" occur with the travertine. This
deposit is developed by a quarry face 225 feet long by
40 feet high and by four prospect tunnels.
A quarter of a mile to the east in SW'/SW'/ sec. 34,
small, irregular veins and masses of travertine are ex-
posed over an area 300 feet by 200 feet. The travertine
is white to honey brown, banded, fine to very coarse
crystalline, locally vuggy, and somewhat brecciated.
These deposits are developed by small prospect cuts
and pits in which the veins range in thickness from a
few inches to a few feet. Exposures on the ridge to the
east may also be travertine. The deposits appear to be
too small to be of economic interest.
The only record of production is by the California
Lime and dement Company from 1900 to about 191 1.
Most of the travertine was used to make lime at the
Carnegie Brick and Pottery Company plant. Some
limestone also was shipped to Stockton for use in glass
making. Minor prospecting east of the main deposit
was done more recently, but details are lacking.
Other reference: Clark, 1955, p. 39.
Collins deposit. Location: Sec. 30, T. 2 S., R. 3 E.,
M.D., 1 or 2 miles southwest of Altamont; Altamont
7'/2-minute quadrangle. Ownership: Oraham Nissen,
Livermore (1966).
"A small outcrop of crystallized limestone" is re-
ported by Aubury ( 1906, p. 64) on the summit of a hill
in sec. 30. As shown by Huey (1948, plate 1), sec. 30
20
California Division of Mines and Geology
Bull. 197
is underlain by sandstone of the Panoche Formation
(Upper Cretaceous) which is locally overlain by the
Cierbo Formation (Miocene). A fossiliferous zone
containing abundant oysters 50-to-150 feet above the
base of the Cierbo is mentioned by Huey ( 1948, p. 41 ) .
According to Ron Hart (personal communication,
1966), the Collins deposit is an impure shelly lime-
stone that caps a small knoll. It lies flat and is exposed
through a thickness of about 20 feet and over an area
about 100 feet across.
Other references: Logan, 1947, p. 206; Davis, 1950, p. 343.
Highway One deposit. Location: NW cor. sec. 1 1
(proj.), T. 4 S., R. 6 W., M.D., in Pacifica, just south
of Rockaway Beach; San Mateo 1 5-minute quadrangle.
Ownership: Not determined (1962).
A small body of typical light-gray, fine-grained,
thin-bedded limestone of the Franciscan Formation is
exposed on a knoll just east of State Highway 1. The
limestone contains interbeds of chert and appears to
grade locally into altered calcareous tuff(r). The stra-
ta, which are exposed over an area about 400 feet in
diameter, are complicated by faults and folds. Re-
serves are estimated to amount to 300,000 tons.
The deposit is developed by a small quarry having
an area of 200 feet by 100 feet and a relief of 25 feet.
The use of the quarried rock is unknown, as the depos-
it has been idle for many years. Foundation remnants
at the deposit may have been for a crusher and other
processing equipment (see Eckel, 1933, p. 354).
Other deposits, either smaller or less pure, lie near-
by to the east and southwest (Darrow, 1963, plate 1).
As these deposits are situated in a residential area,
their future potential as crushed rock sources would
seem to be quite limited.
Hilltop deposit. Location: Near center sec. 1 1, T.
5 S., R. 5 W., M.D., 4'/2 miles southwest of San Mateo;
San Mateo 1 5-minute quadrangle. Ownership: Gran-
ite Rock Company, P. O. Box 151, Watsonville (1964).
This deposit consists of a sequence of Franciscan
limestone and chert beds just west of the crest of Ca-
hill Ridge. It is a northwest-trending mass which
crops out intermittently over an area 1,200 feet by 100
to 250 feet and is associated with greenstone and
vesicular basalt. The latter appears to overlie the lime-
stone. The beds are considerably crushed and broken
but appear to dip moderately southwest except at the
southeast end where they seem to dip gently
northeast. The limestone is light gray to dark blue-
gray, dense, fine grained, and thinly bedded. Thin
interbeds of dark chert occur throughout the deposit
and may constitute as much as 40% of the volume. A
chemical analysis of a sample representing a 35-foot-
thick section of "blue" rock shows 44.96% CaO, 0.36%
MgO, 2.23% Al20„ 0.58% Fe20„ and 15.59% SiO,
(Walker, 1950b, p. 7, table 2). Walker indicates the
exposed thickness of limestone to be 55 feet.
Just when development began is not known, but the
deposit was last quarried in 1951. In that year, the L.
C. Smith Company obtained crushed rock for use in
road construction in the city of San Mateo. Two quar-
ry faces were developed — the northwest face being
270 feet by 40 feet and the smaller southeast face 100
feet by 40 feet (Davis, 1955, p. 436). It is estimated that
50,000 to 100,000 tons of rock were excavated. The
deposit was acquired about 1963 by the present owner,
who drilled several inclined holes to assess potential
reserves. Limestone reportedly was encountered to an
inclined depth of at least 100 feet in one of the test
holes. Reserve figures are not available but probably
amount to several hundred thousand tons of rock. The
large amount of chert present probably limits the
deposit to structural (crushed rock) uses.
Lime Ridge (Cowell) deposits. Location: Sees. 7,
8, 17, and 20 (proj.), T. 1 N., R. 1 W., M.D., 1 to 3'/2
miles southeast of Concord; Walnut Creek and Clay-
ton 7'/2-minute quadrangles. Ownership: Main depos-
its— Newhall Land and Farming Company, 25
California Street, San Francisco; northwest deposits
(sec. 7) — L. R. and M. Ginochio(P), Antioch, and
possibly others (1962).
Surficial deposits of travertine and calcareous tufa
on Lime Ridge were utilized extensively in the past
for cement, lime, sugar rock, flux, and soil condition-
ing. Initial development of the deposits may have been
by a man named Shreeve who worked the "Mt. Diablo
quarries" and burned lime near Pacheco (2 miles west
of Concord) in 1851 (Logan, 1947, p. 220). Early pro-
duction of limestone on Lime Ridge seems to be veri-
fied by Crawford (1896, p. 628). As records were not
kept prior to 1903, there is little information on early
development.
From 1903 to 1915, Henry Cowell Lime Company
(since known as Henry Cowell Lime and Cement
Company) produced travertine for use in lime manu-
facture. The limestone was quarried at the main
deposits (probably in sec. 17) and shipped first to a
kiln in Concord and later to four continuous kilns
near the quarry (Davis and Goldman, 1958, p. 527). A
cement plant was constructed north of the main
deposits in 1907, and portland cement was produced
from 1908 to 1946. Travertine and calcareous tufa
from sec. 17 (proj.) and clay and sand from nearby
deposits were used as basic raw materials in cement
manufacture. Plant operations ceased in 1946 because
of the loss of rail facilities and the approaching deple-
tion of limestone reserves. The mill equipment was
sold in 1952, the main building being used as a ware-
house thereafter. Production capacity of the Cowell
cement plant was rated at 4,800 barrels of cement per
day.
Spreckels Sugar Company also worked the main
deposits on Lime Ridge for many years prior to 1915.
They quarried travertine south of the Cowell quarries
in N'/2 sec. 20 (proj.) for use in beet sugar refining and
1978
LlMESTONl IN I HE COAS1 R VNG1 S
21
as a smelting flux at the ASAR(X) smelter at Selby.
The Cowell interests acquired the Spreckels holdings
in 1915 (Logan, 1947, p. 221).
The only other known production was by Mount
Diablo Lime Marl Company from 1924 to 1927 when
calcareous tufa and travertine were quarried from the
small northwest deposits in sec. 7 (proj.). The princi-
pal production probably came from the quarry just
north of Treat Lane. The material was crushed and
ground for sale mainly as a soil amendment. Some
travertine also was sold to the Mountain Copper Com-
pany at Martinez as a flux for smelting (Laizure, 1924,
p. 85). L. C. Hopper acquired a lease on the property
in September 1926 and may have produced a little
limestone (Laizure, 1927, p. 16). Although the north-
west deposits have not been utilized as commercial
sources of limestone for many years, the carbonate
rocks and underlying sandstone half a mile northwest
of Treat Lane (N'/2 sec. 7) have been excavated in
recent years, apparently for fill purposes.
Carbonate rocks are found in two distinct areas on
Lime Ridge and are referred to herein as the main and
northwest deposits. By far the most extensive are the
main deposits, which cover an irregular area centering
in sec. 17 (proj.) and extending into SE'X sec. 8 and
N'/2 sec. 20. Altogether, these deposits cover close to
half a square mile on both sides of Lime Ridge but
mainly on the southwest side. The northwest deposits
are much smaller, covering 10 acres or less along the
crest of Lime Ridge. They consist of three small
deposits, the largest lying just north of Treat Lane and
half a mile southeast of the other two.
Even though limestone reserves are largely deplet-
ed, quarry exposures indicate that the deposits were
thicker than 15 to 20 feet in only a few places. The
deposits consist of travertine and calcareous tufa de-
posited surficially in and on sandstone of Eocene age
(Domengine Formation to the southeast; Markley
Formation to the northwest). Carbonate-rich spring
waters emanating during (Quaternary time from a
northwest-trending fault and associated fractures are
believed to have caused formation of the deposits.
Deposition of carbonate materials has apparently
ceased, except possibly in SE'/i sec. 8 where there is
some spring activity.
Travertine appears to be the highest quality carbon-
ate rock present, but its relative abundance is uncer-
tain. It is gray to tan, dense, hard, fine grained, and
generally faintly banded and swirled. It is commonly
brecciated and recementcd with coarse crystalline cal-
cite. The travertine probably ranges from calcitic frac-
ture fillings in sandstone on one hand to calcareous
tufa on the other. The calcareous tufa generally over-
lies the travertine and represents a later or more surfi-
cial stage of deposition. The tufa is off white to tan,
soft, porous, and crudely stratified. It is somewhat
impure and may actually grade into caliche, from
which it is difficult to distinguish. Chemical analyses
of the various types of carbonate rock are given in
table 4. Aside from artificial cuts, the carbonate
materials are poorly exposed and commonly veneered
with soil. The hummocky topography and brecciation
features indicate that the deposits are broken and com-
plicated by faults and landslides. The geologic features
of the Lime Ridge deposits are depicted by Ivan Col-
burn in his doctoral thesis in geology (1961, Stanford
University) .
Table 4. Chemical onalyses in percent by weight of carbonate
rock from Lime Ridge (main deposits). Contra Costa County.
Oxides
Lime
Lime
Lime
(dried
Ridge
Ridge
Ridge
basis
til
#2
- t
Ign loss (CO. - H O)
42.25%
43 42%
366%
CaO
49.70
54.03
42.8
MgO
0.0
0.51
0.3
SiOj
7.20
0.91
13.6
AljO,
0.42
0.19
5.0
Fe.O,
0.18
0.15
0.3
Na,0
N.D.
N.D.
0.5
K,0
N.D.
N.D.
0.6
P,0,
0.02
0.02
0.01
Total
99.77%
99.23%
99.71%
N.D. = Not done
Samples collected 1 1-7-62 by F.arl W. Hart and analyzed February and March
196i by Lydia Lofgren, Division of Mines and Geology.
Sample 1 — typical calcareous tufa; soft, porous, light tan; from main quarry-
near Treat Lane. E'/j 7 — IN — 1W (proj.)
Sample 2 — typical travertine, buff to tan. hard, dense, fine grained w ith some
crystalline vein calcite. from quarry in NW', SEV. 1" — IN — 1W (proj ).
Sample 3 — impure calcareous tufa or caliche; light tan. soft, porous, with
some sand and rock fragments, from quarry in SW1/, 17 — IN — 1W
(proj.).
Development of the Lime Ridge deposits is quite
extensive, and virtually all deposits were worked to
some degree. The principal workings center in S'/2 sec.
17 where a series of quarries, benches, and pits are
developed in an irregular and often merging pattern.
Most cuts are shallow but some are as high as 40 to 50
feet and one large benched quarry has a relief of 200
feet. Less extensive workings are found at the main
deposits in N'/4 sec. 20, N'/2 sec. 17, and SE'/i sec. 8.
Although the amount of material quarried cannot be
determined from the irregular workings, as much as
10 million tons of carbonate rock may have been pro-
duced from the main deposits if the cement mill oper-
ated even close to capacity. In the northeast area, each
of the three deposits is developed by quarries. The
deposit near Treat Lane was worked by two quarries,
the largest being about 125 feet in diameter and 20 to
30 feet deep. Production here is estimated to have
totaled 15,000 to 20,000 tons. Half a mile to the north-
west, two deposits 600 feet apart are developed by
quarries which may have yielded 10,000 tons of car-
bonate rock.
Reserves of travertine and related carbonate rock
are impossible to estimate but are almost totally con-
fined to the main deposits. At the main deposits, the
reserves reportedly were approaching depletion (Da-
vis and Vernon, 1951, p. 567). Calcareous tufa and
22
California Division of Mines and Geology
Bull 197
other impure carbonate material appear to constitute
the bulk of the reserves.
Other references: Aubury, 1906, p. 66; Huguenin and Costello, 1920, p.
51-53, 55; Loizure, 1927, p. 912, 15-16.
McLaughlin lithographic stone deposit. Loca-
tion: SW'/4SW'/4(?) sec. 35, T. 1 S., R. 2 W., M.D., 3'/2
miles southwest of Danville; Concord I 5-minute quad-
rangle. Ownership: R. and A. Mueller, Oakland
(1950).
Hard, locally siliceous limestone occurs as a 5-foot
bed between sandstone and conglomerate, apparently
at the head of Cull Canyon. The bed dips 75° SW and
can be traced over a length of 570 feet. It was quarried
about 1905 by A. Ramage, who exposed a face 25 feet
long by 20 feet high (Huguenin and Costello, 1920, p.
23). The stone was tested for lithographic use but was
considered unsuitable for that purpose. The deposit
may be part of the Mulholland Formation of Pliocene
age (Ham, 1952, p. 15, 22, plate 1).
Although the McLaughlin body is not shown on
Ham's map (1952, plate 1), other small lenses of fine-
grained, blue-gray to white, impure limestone of the
Orinda-Mulholland unit are indicated in sees. 11 and
12, T. 2 S., R. 2 W„ and sec. 6, T. 2 S., R. 1 W. Ham
also shows a lens of white limestone in SW1/ sec. 6 in
the Cierbo Formation (Miocene) which he states was
tested and found unsuitable for lithographic purposes.
Because these limestone lenses are small and impure,
their future use would seem to be as local sources of
crushed rock. Apparently the blue-gray limestone has
been used locally for crushed rock (Ham, 1952, p. 22).
Ron Hart of Exploration Logging, Inc., (personal
communication, 1967) reports that a small lens of
limestone 200 feet long by 20 feet thick is exposed near
the S/ cor. sec. 35. This deposit had been recently
developed by a small quarry.
Other references: Laizure, 1929, p. 433-434; Logan, 1947, p. 206.
Middle Fork deposit. Location: NW1/ sec. 19, T.
4 S., R. 5 W. and NE1/ sec. 24, T. 4 S., R. 6 W., M.D.,
2 miles southeast of Pedro Valley (Pacifica); San
Mateo 1 5-minute quadrangle. Ownership: Not deter-
mined (1962).
A fairly large, northwest-trending lens of Francis-
can limestone is shown along the Middle Fork of San
Pedro Creek by Darrow (1963, plate 1). The mass is
shown to be nearly a mile long by an average of 300
feet wide in outcrop and to dip 30° to 60° NE. A large
tonnage of limestone is indicated by Darrow's map.
However, during a brief examination of the north end
of the deposit, only scattered limestone outcrops and
float were seen over a width of 200 feet. The limestone
is typically light and dark gray and contains chert
interbeds, as well as redistributed silica.
The paucity of limestone outcrops may indicate that
noncarbonate rocks are extensively associated with
the limestone, or it may reflect crushing and fractur-
ing because of the proximity of the Pilarcitos fault.
The deposit is totally undeveloped but warrants suffi-
cient prospecting to permit an economic evaluation. If
there is any reasonable continuity of limestone
between outcrops, accessible reserves for crushed rock
uses may amount to several million tons.
Mission Lime Marl (Gallegos) deposit. Location:
SW cor. sec. 31, T. 4 S., R. 1 E., M.D., 2'/2 miles east
of Irvington and just east of Mission San Jose; Liver-
more 1 5-minute quadrangle. Ownership: Gallegos
family, State Highway 9, Mission San Jose (1962).
This is a small surficial deposit of travertine and
calcareous tufa that rests on calcareous and fossilifer-
ous sandstone of the Briones Formation (Miocene) . It
is at least 6 to 8 feet thick. The deposit mainly consists
of grayish-brown to tan, hard, vuggy, fine-grained
travertine and well-bedded, dirty-white to light-tan,
porous, soft, impure, calcareous tufa. Travertine out-
crops and float are found sporadically over an area
about 300 feet in diameter. At the quarry, the tufa
generally overlies the travertine and probably is
younger. A chemical analysis of the tufa as reported in
Laizure (1929, p. 434), showed 83.1% CaCO,. The
travertine appears to be considerably purer than that.
When examined in 1962, the deposit workings con-
sisted of an irregular quarry (trench) about 100 feet
long by 20 to 30 feet wide (average) by 8 feet deep
(maximum) and one or two minor test pits. Small
amounts of agricultural limestone (tufa?) were pro-
duced around 1924 by Mission Lime Marl Company
(Laizure, 1924, p. 184). In 1928, W. S. McLean pro-
duced some travertine for terrazzo and other orna-
mental uses. Some of the material also may have been
used as a source of lime manufactured at Mission San
Jose in the nineteenth century (Irelan, 1888, p. 35).
There has been no development in recent years. Based
on quarry size, total production is probably less than
1,000 tons. Carbonate rock reserves are undetermined
but small.
Other reference: Logan, 1947, p. 206.
Mitchell deposit. Location: SW1/, sec. 32, T. 3 S.,
R. 4 E., M.D., 1 2 miles east-southeast of Livermore and
1 mile south of Corral Hollow; Altamont 7'/2-minute
quadrangle. Ownership: Not determined.
A.S. Huey ( 1948, p. 62) mentions a "lime rock pros-
pect . . . developed in Franciscan rocks about a quarter
of a mile south of the Tesla fault." The limestone
apparently occurs as thin lenses in shale and chert
(Huey, p. 18). The deposit lies a quarter of a mile
northeast of Mitchell Ravine.
Oil Canyon (Harkinson) deposit. Location: Sees.
15 and 16, T. 1 N., R. 1 E., M.D., 5 to 6 miles southwest
of Antioch; Antioch South 7'/,-minute quadrangle.
Ownership: Not determined.
A 6-foot-thick ledge of impure limestone in Oil Can-
yon was developed on the land of Colonel Coates prior
to 1894, when several tons of rock were shipped to
1978
1.IM1 SIOM IN I I IK C.OASl R.WCiKS
23
Antioch for testing as a source of portland cement
material (Crawford, 1894, p. 380). It has been de-
scribed as "an amorphous, compact, bluish-gray, fos-
siliferous limestone" by Aubury (1906, p. 67). The
limestone is probably part of a sequence of Upper
Cretaceous rocks in which thin limestone beds, con-
cretions, and shell horizons are not uncommon (Col-
burn, 1961, p. 11 and plate I).
Orinda deposit. Location: NE'/4 sec. 15 and adja-
cent parts of sees. 10 and 14, T. 1 S., R. 3 W., M.D., 2
miles south-southeast of Orinda; Concord 15-minute
quadrangle. Ownership: Not determined (1962).
A large, northwest-trending body of impure lime-
stone 500 feet wide bv half a mile long is reported
between the Siesta and Moraga Formations of Plio-
cene age (Lawson, 1914, p. 22, and Concord map).
Where examined in NE'/4NE'/4 sec. 15, the carbonate
unit is exposed only as scattered outcrops and proba-
bly is interbedded with softer noncarbonate beds. The
carbonate rock is pale buff to tan, hard, dense, fine
grained, dolomitic, siliceous and locally brecciated,
and recemented with calcite. It is likely that the lime-
stone was deposited as a tuffaceous or marly lake bed.
I he deposit is undeveloped and appears to be useful
only as a local source of crushed rock.
Lawson (1914) also shows several small lenses of
Siesta and Moraga limestone half a mile to the north
in sec. 10 and to the northwest in sees. 5 and 6.
Patterson Pass deposit. Location: Sec. 10, T. 3 S.,
R. 3 E., M.D., 7'/, miles east of Livermore; Altamont
7',-minute quadrangle. Ownership: Not determined.
An unimportant travertine prospect of apparent
hot spring origin is reported in the center of sec. 3 just
north of the Patterson Pass road (Huey, 1948, p. 62).
Picardo Ranch deposits. Location: S'/2 sec. 12, T.
4 S., R. 6 W. (proj.), M.D., l'/2 to 2 miles southeast of
Rockawav Beach, Pacifica; San Mateo 15-minute
quadrangle. Ownership: Louis Picardo, Pacifica
(1962).
Several lenses of Franciscan limestone form a group
of deposits that extends two-thirds of a mile north-
westerly from the North Fork of San Pedro Creek
(Darrow, 1963, plate 1). The largest of these, at the
southeast end of the group, is shown to be 800 feet
long by 250 to 300 feet wide and is exposed through
200 feet of relief. This body, which was not examined,
mav contain 1 to 2 million tons of limestone and as-
sociated rock.
Just over the ridge to the west is a triangular-shaped
bodv 500 feet long with a maximum width of 300 feet
and a relief of 200 feet. The limestone is typical of that
of the Franciscan Formation, consisting of thinbed-
ded, fractured, dark-bluc-gray limestone and interbed-
ded chert, with lesser amounts of light-dove-gray
limestone. Reserves probably are less than half a mil-
lion tons. Development of this deposit consists of a
small hilltop quarry from which fractured rock was
obtained around 1960-61 for use as road base and
drain rock in the construction of the nearby high
school. The amount of material quarried is unknown.
The quarrv was idle in May 1962.
Several other small limestone deposits are found
nearbv one of which may be a westward extension of
the developed deposit. There are no chemical analyses
or other information on the Picardo Ranch deposits,
and only the one quarry is known. Total reserves may
be 3 to 4 million tons. Considering the presence of
chert with the limestone, it seems likely these deposits
will be of value principally as local sources of crushed
rock.
Pilareitos Creek deposits. Location: W'/2 sec. 11,
T. 5 S., R. 5 W., M.D., 4 miles northeast of Half Moon
Bay (town); San Mateo 15-minute quadrangle. Own-
ership: Not determined (1962).
Typical gray limestone with interbedded chert of
the Franciscan Formation is exposed in SVV'/4N\V'/4
sec. 1 1 on the northeast bank of Pilareitos Creek. The
dimensions of the body are concealed by dense vegeta-
tion. However, the Pilareitos fault, whose trace ap-
proximately coincides with the southeast-flowing
creek, probably limits the deposit to the southwest.
The deposit is developed by a small quarry from
which crushed rock reportedly was obtained more
than 20 years ago for local road use.
Less than half a mile to the south, Pilareitos Creek
veers southwestward and crosses scattered outcrops of
impure crvstalline limestone similar to the Sur Series.
Although Lawson ( 1914, map) shows the limestone as
a single northwest-trending mass half a mile long on
the southwest side of the Pilareitos fault, he (Lawson,
p. 4 and 22) indicates the deposit to be impure (mag-
nesia, silica) and small ("limited to a few acres").
Heavy vegetation covers much of the deposit area.
Small crvstalline limestone deposits of similar type
are also reported along the ridge top l'/4 miles to the
west-northwest (Elmo Adams, 1962, oral communica-
tion). The limestone outcrops southwest of the fault
probably represent small pendants in quartz diorite.
They are probablv too small and impure to be of eco-
nomic value.
Pleasanton (Pleasanton Lime and Cement Com-
pany) deposit. Location: N\V4 sec. 4 and NE'4 sec.
5, T. 4 S., R. 1 E. (proj.), M.D., 2'/2 miles south of
Pleasanton; Livermore 1 5-minute quadrangle. Owner-
ship: Herman Koopman, Route 1, Box 198, Pleasanton
(1962).
Small deposits of grayish-tan, well-indurated, sandy
coquina lenses interbedded with fossiliferous, massive
sandstone of the Briones formation (Miocene) are
boldly exposed for half a mile southeast of the railroad
cut near the north boundary of sec. 5. The resistant
sandstone-coquina unit is several hundred feet thick
and dips 70° to 80° SW. The coquina occurs in this unit
as scattered lenses as much as 40 feet thick. Very local-
24
California Division of Mines and Geology-
Bull 197
lv, the coquina approaches pure limestone in composi-
tion; but it is generally quite sandy, grading into
fossiliferous (calcareous) sandstone. A sample of typi-
cal sandy coquina from the small quarry was analyzed
bv Matti Tavela of the Division of Mines and Geology
in August 1963 and showed the following content:
36.5% CaO, 0.78% MgO, 23.0% Si02, 3.7% A120„
0.78% Fe20„ 0.10% P2Os. Although total reserves of
impure coquina may aggregate several million tons,
good quality limestone is practically nonexistent.
The Pleasanton deposit was worked around 1917 by
Pleasanton Lime and Cement Company as a source of
agricultural lime. Sandy coquina was obtained in
NW1/ NW'X sec. 4 from a narrow hillside quarry
where a face 60 feet long by a maximum of 30 feet high
was worked. The limestone was hauled via narrow-
gauge rail to a nearby plant and burned in two oil-
fired kilns. At the quarry, an adit (now caved) report-
edly was driven 50 feet northeast to explore the depos-
it. Not more than a few thousand tons of limestone
was produced.
References-. Huguenin and Costello, 1920, p. 22; Laizure, 1929, p. 434;
Logan, 1947, p. 206; Hall, 1958, map.
Rockawav (Calera Hill) deposit. Location: Ap-
prox. NW'/4 SW'/4 sec. 2 (prop, T. 4 S., R. 6 W., M.D.,
in Pacifica just north of Rockaway Beach; San Mateo
15-minute quadrangle. Ownership: Ideal Cement
Company, 420 Ideal Cement Building, Denver, Colo-
rado 80202; leased by Rhodes-Jamieson, P. O. Box 1 18,
Oakland (1970).
The Rockaway deposit is a large mass of Franciscan
limestone situated west of State Highway 1, where it
forms a resistant prominence known as "Calera Hill".
It has yielded large amounts of limestone and associat-
ed chert for use as aggregate and other crushed rock
products (Davis, 1955, p. 436; Logan, 1947, p. 308;
Huguenin and Costello, 1920, p. 178). The limestone
also may have been used as a source of lime, because
the remains of some kilns are reported (Eckel, 1933, p.
3 54). The earliest record of production is for E. B. and
A. L. Stone Company, who operated a quarry from
1910 to April 1919. Apparently, the deposit then lay
idle until 1942 but has been active ever since. The
other operators include Rockaway Quarry, Inc., 1942-
1953; Marks Materials, 1953-1967; and Rhodes-Jamie-
son since 1967. Just when Ideal Cement Company ac-
quired ownership of the property is not known, but
the limestone has not been used to manufacture ce-
ment.
This deposit has been described and mapped as a
200-foot-thick sequence of limestone and associated
chert exposed over a triangular area 1,400 feet by 900
feet (Darrow, 1963, p. 12-13, plate 1 ). It originally was
exposed through more than 300 feet of relief from sea
level to the top of the hill. The beds form a syncline
that plunges 45° N W, and they are truncated on the
north l>v a fault. Minor faults and folds also seem to
complicate the structure locally. The mass consists of
a well-bedded, highly fractured sequence of light and
dark limestone with thin interbeds and nodules of
chert. The percentage of chert varies from place to
place but constitutes a substantial portion of the
deposit. Interbeds of greenstone and other altered
rocks are also present to some extent. The light lime-
stone is distinct, being light dove-gray, fine grained,
dense, and foraminiferal. Limestone that is free from
visible impurities is represented by the chemical anal-
ysis of sample 2 in table 5. An analysis of a composite
sample representing a 35-foot section of light lime-
stone, as given by Walker (1950b, table 2), shows
48.73% CaO and 10.85% Si02.
Contrasting with the above is the dark limestone
which is generally dark blue-gray, fine crystalline,
dense, bituminous, and commonly well laminated and
platy. Although not as obviously associated with chert
beds as the light limestone, the dark limestone is often
quite siliceous. Variations in chemical composition
are indicated by samples no. 1 and 3 (table 5), neither
of which contained visible chert beds. A composite
sample representing a 40-foot sequence of dark lime-
stone is shown by Walker (1950b, table 2) to contain
44.81% CaO and 16.73% SiO;. Other analyses are
given in Logan (1947, p. 308) and Eckel ( 1933, table
2).
Table 5. Chemical analyses of limestone from the Rockaway
deposit, San Mateo County.
Rockawav Rockawav Rockaway
(hide #/J *2_ #3
CaO 25.0% $4.50% 53.50%
MgO , 0.5 0.51 0.51
SiO; 50.0 1.67 1.57
Al,0, 0.38 0.19 0.35
Fe,0, 0.30 0.10 0.17
PA 0.08 0.07 0.16
TiO, 0.08 ND ND
Organic C 2.7 ND ND
Ignition loss (less C) 22.0 42.96 43.39
Total 101.04 10000 9965
ND = Not done
* Adjusted analysis
Sample I — typical dark blue-gray finely-crystalline, bituminous limestone
with no visible impurities.
Sample 2 — typical light dove-gray, fine-grained, foraminiferal limestone with
no visible impurities.
Sample 1 — similar to sample I but partly weathered buff and platy.
Analyzed by Lydia l.ofgren, California Division of Mines and Geology,
1962.
When examined in May 1962, the deposit was devel-
oped from the southeast side by a quarry about 500 by
700 feet with a maximum face of about 150 feet. This
is bordered to the north and west by a series of
benches, the highest of which may be 200 feet above
the quarry floor. A tunnel adit on the east side of the
deposit is all that remains to indicate the former glory-
hole operation of E. B. and A. L. Stone Company.
From the extent of the workings in 1962, it is estimat-
ed that roughly 3 million tons of materials have been
quarried at this deposit.
I.imisiom in i in •.Coast Ranof.s
25
In recent (1962) quarry operations, the fractured
limestone and chert are ripped from the upper
benches and bulldozed to the quarry face, falling to
the quarry floor below. Only occasional blasting is
needed. Some selective quarrying is necessary to
maintain a uniform product. Thin soil overburden
and occasional soft, noncarbonate interbeds are
moved to the west slope of the hill where they are
wasted At the quarry floor, the rock is bulldozed to
a grizzly, where the oversize rock is reduced in a jaw
crusher. Both fractions are conveyed to the crushing-
screening plant, which has a capacity of 250 tons per
hour. At the plant, the minus l'/2-inch material is
removed and stored for use as road base material. The
plus 1%-inch rock is crushed to five sizes, including
sand, by one jaw and three cone crushers and a roll.
The material is then stored in open piles for use as
asphalt and portland cement concrete aggregates,
drain rock, roofing gravel, and other purposes. Proc-
essing is drv, although some products are occasionally
washed. Large boulders left in the quarry are used for
riprap and landscaping. Most of the aggregate pro-
duced is utilized at the quarry in an asphalt plant
owned by Marks Material, Inc., and a readymix con-
crete plant owned by H. E. Casey of San Mateo.
Available reserves of the Rockaway deposit amount
to about 2 million tons of usable rock above sea level —
assuming the limestone extends to that depth through-
out the deposit and the amount of wastage does not
increase significantly.
Other references: Lawson, 1914, p. 22 and map; Kelly. 1933, p. 362-363;
Walker, 1950b. p. 4, 5, 7.
San Francisco Bay Shell deposits (Ideal Cement,
Pioneer Shell, South Bay Dredging, Bay Shell).
Location: South arm of San Francisco Bav; mainly T.
3 and 4 S., R. 3 and 4 W., M.D.; San Mateo, Hayward,
and Palo Alto 15-minute quadrangles. Ownership:
Multiple, but mainly Ideal Cement Company, 420
Ideal Cement Building, Denver, Colorado 80202, and
State of California (1967).
Accumulations of shells are found in many of the
shallow bays and inlets of California. By far the largest
are the accumulations of native oysters (Ostrea lurida
Carpenter) deposited in Holocene time in south San
Francisco Bav. The deposits of south San Francisco
Bav have served as the principal sources of shells
dredged in California and, since 1962, have been the
sole source of shells dredged in the state. Prior to 1962,
oyster shells also were dredged commercially from
Newport Bay in Orange County.
Although oyster shells were obtained from San
Francisco Bay as early as 1891 for garden w alks and
other purposes (Skinner, 1962, p. 95), shells were first
dredged commercially in 1924 for livestock feed and
soil conditioning. Since 1925, when a cement plant
began production at Redwood City, the shells have
served mainly as cement raw materials. From 1931 to
about 1950, shells also were calcined to make lime,
which was used for reacting with salt works bittern to
produce magnesium compounds. In recent years,
three companies have been active in shell dredging.
Ideal Cement Company was the major producer, util-
izing shells and associated mud for the production of
cement. * Pioneer Shell Company dredges and proc-
esses shells mainly for cattle and poultry feed. South
Bav Dredging Company also dredged and washed
shells but sold all of their product to Bay Shell Com-
pany' for further processing and eventual sale for live-
stock feed and soil conditioning. **
A summarv of past and present operations, as of
1969, is given in table 6. More detailed data appear
below under individual company descriptions.
Occurrence of Shells
In spite of many years of commercial shell dredging,
numerous technical reports on the sediments of the
bay, and thousands of drill, core, and dredge samples
collected, surprisinglv little detail is known about the
size, extent, and characteristics of the individual shell
accumulations. Most investigations of the bay sedi-
ments treat the shell occurrences incidentally or in
only general terms. The sediments of San Francisco
Bav are probably best summarized by Treasher
(1963) and Trask and Rolston (1951). Detailed data
on the Holocene sediments, in which most of the
shells occur, are presented in unpublished reports by
Conomos (1963) and Gram (1966). Investigations
specifically concerned with shell deposits are reported
by Hart (1966a) and Story et al. (1966). Many other
pertinent references are listed by Trask (1953), Terry
(1955), and Goldman (1969).
The principal shell accumulations consist of native
oysters deposited in the shallow parts of south San
Francisco Bay. Most of the deposits lie in the upper
part of a Holocene soft mud unit — referred to as
"younger bay mud" by Treasher (1963). Partly ve-
neering this unit are surficial modern oyster shell ac-
cumulations. Both the mud-associated and the
surficial deposits have been dredged commercially,
but the former constitute by far the largest reserves.
Shells exposed on the bay bottom, excluding periph-
eral beaches and bars, indicate the general areas where
buried shell deposits exist (figure 2).
Smaller deposits of oyster shells also occur with
older bav mud but are too small and deeply buried to
be of economic value. Fragmental shells (mostly
clams) associated with sand in several parts of the bay
conceivably could be a source of shells but have not
been dredged for that purpose.
The principal shell occurrences — younger bay mud
deposits, surficial deposits, and shells associated with
sand — are described below.
• Shell-dredging and cement manufacture by Ideal Cement Company ceased
at the end of l°70 (See footnote l>clow under Ideal Cement Company)
" Shell-dredging by South Bay and processing by Bay Shell ceased in lu69
26
California Division of Mines and Geology
Bull 197
Figure 2. Map showing distribution of oyster shells in southern San Francisco Bay.
1978
LlMESTONI IN I 111 COAS1 K VNG1 S
27
Toble 6. Summary of known producers and processors of oyster shells of south San Francisco Bay.
Xjme of
operator and \ c.ir* jclne
Source of shells
Remarks
Bav Shell Co, (was Agricultural Lime S Compost Co ) 1924-
1969
Ideal Cement Co (was Pacific Portland Cement Co.) 1925-1969
(active)
Ortlev Shell Co iW B Ortlevl 1930-1941
Pioneer Shell Co (Capt L H Beck. Beck Dredging Co.)
1969 (active)
19)1-
Purchased from South Bay Dredging,
previously purchased from Beck Dredg-
ing; also mav have dredged near Alviso
and San Mateo Bridge pre-1950(?).
Dredges shells and mud east of channel
near San Mateo Bridge and barges to
plant; also buys washed shells from Beck
Dredging.
Reportedly did own dredging.
Dredges near San Mateo Bridge east of
channel, may have dredged south of Dum-
barton Bridge.
Processed shells for livestock feed and soil
conditioning a! plant in Alviso Operations
ceased 1969.
Manufactures cement at Redwood City plant,
using w ashed shells to "sweeten"; previous to
195(1 w ashed and processed shells for livestock
feed and soil conditioning
Shells processed for poultry feed at Alviso
plant.
Washes shells on dredge and delivers to own
plant in Petaluma for livestock feed and soil
conditioning; previously sold washed shells to
Ideal Cement, Westvaco Chlorine Products
and Bay Shell companies; formerly processed
shells for commercial sale at plant near Al-
South Bav Dredging Cxi (Pete Gambetta) 1953 (or earlier)-
1969
Westvaco Chlorine Products Corp. (was California Chemical
Corp ; now is Inorganic Chemicals Div., FMCCorp.) 195 1-1948
Dredged north of San Mateo Bridge and
east of channel, probably dredged south of
Dumbarton Bridge earlier
Purchased from Beck Dredging
Washed shells on barge and sold to Bay Shell
Co. Operations ceased 1969.
Shells calcined and reacted with bittern to
make magnesian compounds at Newark
plant; some lime, hydratcd lime, and poultry
feed sold commercially (see FMC Corp.).
Younger bay mud deposits. This unit is widely
distributed in San Francisco Bay. It consists mainly of
soft gray mud (silty clay) with interbeds and lenses of
silt, sand, peat, and shells. These sediments were de-
posited following a progressive rise in sea level after
the last glacial episode (Wisconsin (ilaciation) . Shells
accumulated in an environment similar to the present
one. The shells exist as numerous thin lenses of varia-
ble purity that are interbedded with and grade lateral-
Iv into mud. The lenses are largely concentrated in the
upper 30 or 40 feet of the younger bay mud unit. Test
borings show that shell-mud sequences as much as 25
feet thick exist in several places in south San Francisco
Bav and also at the west end of the Richmond-San
Rafael Bridge at the north end of the bay.
Thick sequences of shells probably represent rela-
tively persistent environments favorable to the
growth and accumulation of shells. Shell lenses also
tend to concentrate along certain horizons that are
laterally extensive. Such horizons reflect periods of
greatlv increased populations (population explo-
sions) of the native oyster. The most extensive shell
horizons known lie east of the main ship channel in
south San Francisco Bay.
In 1962, Ideal Cement Company explored these
deposits with 107 drill and core holes in order to eval-
uate their shell holdings. According to Story et al.
(1966, p. 48), the shell horizon in the vicinity of the
San Mateo Bridge is "a fairly extensive layer contain-
ing 4 to 15 feet of oyster shells buried beneath 2 to 8
feet of mud". The layer is reported to contain 10 to
759J- shells (dry basis). Radiocarbon age dates indicate
that this shell horizon was deposited 2300 to 2500 years
ago (Story et al, 1966, p. 48-49). Because most of the
dredged shells are worn and somewhat broken, it is
presumed that the shell deposits are at least partly
reworked debris from oyster reefs and beds or from
older deposits. However, it is likely that eroded rem-
nants of ancient reefs are partly preserved.
Shell deposits of the younger bay mud contain the
bulk of the commercial shell reserves and provide the
raw materials for cement manufacture by Ideal Ce-
ment Company.
Surficial shell deposits. Although the native oys-
ter population has been somewhat decimated since
1900 due to pollution (Skinner, 1962, p. 100), live oys-
ters can be found in many places in sheltered parts of
San Francisco Bay (J. A. Aplin, 1968, personal com-
munication). Extensive beds and cemented reefs, with
clusters of live oysters attached, are most extensive in
shallow parts of the south arm of the bay. Oysters are
also reported in a few places along the rocky perimeter
of the bay. Debris derived from oyster environs, and
perhaps from older deposits, too, has accumulated as
veneers and bars. These loose-shell deposits, as a result
of wave and current action, tend to migrate shoreward
to form beaches in San Mateo County. Such beaches
are reported to have been rather extensive around the
turn of the century. The submerged bars, veneers, and
loose debris around the reefs are easy to dredge hy-
draulically and are believed to be the principal sources
of shells used by Pioneer Shell Company and South
Bav Dredging Company. The beaches, although com-
posed almost entirely of clean shells, are not known to
3 — 89454
2H
California Division of Mines and Geology
Bull 197
Photo 1. Western margin of San Francisco Bay showing shell barrier beach (foreground) and spits which form small tidal lagoon on east side of Brewer Island,
San Mateo County. Beach and spit formed after construction of levees around man-made island.
Photo 2. Close-up of shells (mostly native oysters) that comprise spit of Brewer Island, San Mateo County, formed by wave action in San Francisco Bay.
1978
Limestone in the Coast Ranges
29
be used commercially, although they may have been in variations of individual shell lenses and groups of
the past. lenses are not available. However, some idea ot the
chemical composition of a high-grade mud-associated
Shells associated w ith sand. Fragmental shells, shen deposit is indicated by sample 1 in table 7. The
perhaps composed mostly of clams, are associated sample is a product of hydraulic dredging and un-
with sand in shoal areas north of San Francisco where doubtedlv is higher in lime (CaO) than the in-place
currents are strong. Sand-shell deposits are shown to sample because of the inherent washing effect of the
be exposed northwest and southwest of Angel Island dredging process. Sample 2 (table 7), which is the
by Trask ( 1953, figure B-3). Samples of dredgings just same as sample 1 except that it has been washed, con-
west of Alcatraz Island are reported to contain at least tajns 53 8% lime Samples 3 to 7 are washed shells
50% shells. A 1 5-foot-thick layer of sand containing an from SUrficial deposits and contain 53.07% to 54.31%
undetermined percentage of broken shells also is iime Unwashed sample 8 from a shell beach contains
known at San Bruno Shoal, where the sand is buried zj 9% lime,
under 1 5 to 20 feet of mud and shells. This shelly sand
has been used extensively for hydraulic fill at Foster Development and Reserves
Citv. Whether the shells are distributed through the . . r . n .
j i it i ■ „ |„ • It is estimated that 2} to 30 million tons of shell have
sands or are locally concentrated is unknown. In ei- , . , , lot- r>
, • , i t I i ii j i • u- u been dredged trom south San rrancisco nay since
ther case, it is conceivable that the shell debris, which 5 . .
, . . • , , ii • 1924. I he great bulk ot this was used in the manutac-
tends to be coarser than the associated sand, could be . 6 ..
■ i I . j u ■ „ c. ii u,, •„„ r„„j ture of cement. Most of the shells dredged came trom
easily beneficiated bv screening. Shell-bearing sand , ... . . „ b e ,
i • rcir • uu u a a„Ia ,.„i<, the vicinity ot the San Mateo Bridge east ot the mam
deposits of San I- rancisco Bay have been dredged sole- ' .. . ■ . u
lv for fill purposes so far ' shlP channcl (see f'gure 2>- Some dredging has been
K v reported south of Dumbarton Bridge, and bottom
Composition of Shell Deposits depth changes recorded in nautical charts of different
vears indicate that additional dredging has been done
Samples indicate that more than 95% of the shells near the Qak,and Airporti south 0f Alameda. Recent
dredged commercially are derived from the very pro- dredging by Ideal Cement Company has been con-
l.f.c and widespread native oyster Ostrea lunda Car- ducted just north of the San Mateo Bridge causeway,
penter. This oyster produces a rather flat and very Thfi company operates* a hydraulic dredge with a
thin shell that is a maximum of 2% inches long. Minor cimer head tQ develop a bench-cut that is worked east-
amounts of debris from other mollusks, plus barnacles ward pioneer shel| Company and South Bay Dredg-
and bryozoa, also are present. The presence of the ■ Company" dredge hydraulicallv in water no
Japanese littleneck clam, introduced into the bay in d f than Qr feet,' reportedly near the San
1930, readily differentiates the modern shells from M;Ue() Rrid causewav Surficial deposits of loose
those dredged from older buried deposits. Imported shc„s ^ yeneer (he bay b()ttom Qr accumulate ,ocal.
oysters once raised commercially, may also constitute , afe believcd t() bc thc main sources of shells uscd bv
some of the surficial shell debris locally. these com ies Both Pioneer and South Bav wash
As indicated above, the most important shell depos- ^ she„s aboard thejr dred jor tQ ,ater ss.
its or horizons consist of multiple shell lenses in mud.
The discrete shell lenses also contain variable amounts • operations ceased a. end of i°7o.
of interstitial mud. Specific data on the compositional "South Bay ceased dredging in lvw
Table 7. Chemical analyses of oyster shell samples from south San Francisco Bay.
Oxides (dry weight bisis)
in percent I 2 [ 4 f [ *
Ignition loss J6 Wr •»V4"'r 4! HTr 41 H6<7r 43.60% 4}.00% 43.60% 43.60%
CaO 45.14 * 53.80 53.07 54.31 53.2 53.1 53.1 52.9
MgO 1.58 0.34 0.51 0.51 0.44 0.74 0.64 0.62
SiO, 9.70 1.40 2.15 0.98 0.72 1.5 0.74 0.83
AI,Oj 1.84 0.15 0.34 0.11 0.43 0.84 0.37 0.47
Fe,Oj 1.65 0.11 0.24 0.09 0.11 0.16 0.09 0.09
PjOj 0.17 0.05 0.05 0.05 0.04 0.05 0.05 0.06
\a,0 1.86 ND ND ND ND ND ND ND
K.O 043 ND ND ND ND ND ND ND
Total 99.31% 99.32% 99.50% 99.91% 98.54% 99.39% 98.59% 98.57%
ND = Not done.
Samples 1^1 — analysed by L. 1-ofgrcn, 1962.
Samples 5-K — analyzed by C. Smith and M Tavcla, 1V67.
Sample 1— from Ideal Ccmenl (ai barge. Redwood City planl. unwashed sample dredged easl of channcl near San Mateo Bridge
Sample 2 — same as sample I but washed by hand over a 2H-mesh screen.
Sample I— from primary stockpile of Pioneer Shell Co., Pctaluma; sample dredged, washed and screened near San Mateo Bridge
Samples 4 and 5— from primary stockpile at Bay Shell Co., Alviso; shells dredged, washed and screened near San Mateo Bridge by South Bay Dredging Co
Samples 6 and 7— dried, crushed and screened shell from Bay Shell Co plant. Alviso Sample 6 is "medium shell", sample 7 is "flour shell"
Sample 8 — unwashed shell from beach al Brewer Island. San Maleo County
30
California Division of Mines and Geology
Bull 197
ing for livestock feed and soil conditioning. (See com-
pany descriptions below for additional data.)
Reserves of oyster shells are difficult to ascertain
with the data available. However, it is believed that at
least several tens of millions of tons of shells are avail-
able at a shallow depth (within 20 to 30 feet below the
bay bottom) east of the main ship channel in south
San Francisco Bay. Smaller reserves also veneer the
bay bottom in the same area. Shell deposits along the
San Mateo County shore and elsewhere in the bay are
probably small but may be of economic value. Some
of the deposits south of the Dumbarton Bridge and
along the San Mateo shore reportedly have been used
in the past.
Economics
The shell deposits of San Francisco Bay are actually
thin, low-grade, unconsolidated limestone deposits
that would be far less valuable (or even useless) if
located onshore. Some of the advantages enjoyed by
the shell operators include: 1) simple and inexpensive
mining by dredging; 2 ) ability to beneficiate the shells
inexpensively by washing with bay water; 3) use of
the mud impurities as a source of raw materials (alu-
mina, silica, iron oxide) in the manufacture of cement;
4) flexibility and low cost of transportation of
products within a large marketing area; and 5) low
land cost, especially for an urbanized region.
The disadvantages associated with shell develop-
ment are not always obvious but generally relate to
multiple use and multiple jurisdiction of the Bay.
Manifold problems can develop when dredging, land
filling, shipping, sport and commercial fishing, and
various recreational activities are all carried on in
close proximity to one another. The varied activities
and different areas of the bay are managed by several
local government agencies, as well as by numerous
private land owners.
Land ownership in south San Francisco Bay is com-
plex, and mineral rights to large areas are owned by
both public and private entities. The State of Califor-
nia owns most of the public land, but some land is held
by cities and other government jurisdictions. The
largest private owner, Ideal Cement Company, report-
edly controls about 30,000 acres of bay land between
Millbrae and Alviso. The approximate distribution of
lands owned by Ideal is indicated by Scott ( 1963, chart
opposite p. 4) as lands patented by the Surveyor Gen-
eral. An additional 4,730 acres of State-owned land is
leased by Ideal Cement Company for the purpose of
shell dredging.
Shell Producers and Processors
Bay Shell Company1 . This company operates a
shell-processing plant at 3780 Lafayette Street, Alviso,
Santa Clara County. Bay Shell Company has proc-
essed oyster shells dredged from San Francisco Bay
1 I he Bay Shell Company plant ceased operations in 1969,
since 1924. During its early years, the company re-
portedly dredged shells from "near Alviso" (Logan,
1947, p. 311) and "a point about 2 '/2 miles north of the
San Mateo drawbridge" (Davis and Jennings, 1954, p.
391 ) . In recent years, all of the shells processed by the
company were purchased from South Bay Dredging
Company (which see). Some shells also were pur-
chased from Beck Dredging Company (now Pioneer
Dredging Company) at least as early as 1946. Records
indicate that Bay Shell Company may have dredged
shells as late as 1956. The company was owned by
Santa Clara Sand and Gravel Company in 1962 and by
Steve Dorsa of Saratoga in 1967.
When visited in 1962 and 1967, Bay Shell Company
received washed shells by barge at its plant on Alviso
Slough. Approximately four barge loads (capacity 1,-
000 cubic yards) per month were being delivered. The
shells are unloaded with a clamshell and conveyed to
a small gas-fired rotary kiln for drying. The dried
shells are sized over a multiple hummer screen having
openings of '/2 inch to 10 mesh. A hammer mill is used
to produce finer sizes. Four sizes — whole shell, me-
dium, fine, and flour — are produced. These are sacked
separately or combined as desired. Most of the shell is
sold as poultry feed, but "flour" is sold for soil condi-
tioning and livestock. Based on the name of its prede-
cessor company — Agricultural Lime and Compost
Company — the products were marketed as ALCO
Products until recently. The products are now mar-
keted under the Bay Shell name. Chemical analyses by
Abbot A. Hanks, Inc., of two finished product samples
collected in 1967 showed an average content of 53.1%
CaO (see samples 6 and 7, table 7) . Samples of washed,
but otherwise unprocessed, shells taken from the pri-
mary stockpile in 1962 and 1967 averaged 53.7% CaO
(see samples 4 and 5, table 7). Capacity of the plant
was 7 tons per hour, but this was expanded in late June
1962. Although the property is served by a spur of the
Southern Pacific Railroad, all products were being
trucked to market in 1967.
Photo 3. Bay Shell Company processing plant at Alviso showing hopper
for dredged and washed shells, conveyor belt, rotary drier, screening tower,
and storage silos. Plant ceased operations in 1969.
1978
LlMISIONI IN I HI C()\SI K \N(,I N
J1
F.\fC Corporation (Food Machinery and Chemi-
cal* ( 'orporation; Westvaco Chlorine Products Com -
party; California Chemical Corporation). Westvaco
Chemical Division (now known as Inorganic Chemi-
cals Division) of FMC Corporation and its predeces-
sors purchased oyster shells to manufacture lime at
their New ark plant from 1931 to about 1948. Most of
the lime was used to react with seawater bittern to
precipitate magnesium hydroxide — a basic raw
material used extensively in the chemical and basic
refractories industries. Some lime and hydrated lime
made from shell also were sold commercially — per-
haps .is late .is 1950 In addition, small amounts "I shell
were sold as poultry feed.
The shells were purchased from Captain L. H.
Beck, who dredged in the southern arm of San Fran-
cisco Bav (see Pioneer Shell Company). Although
Westvaco formerly owned shell-bearing land, the
deposit was never developed. The land eventually was
acquired by the Airport Authority for extension of
runways of San Francisco Airport. Recovery of shells
by Captain Beck was by suction dredging. The shells
were washed free of mud aboard Captain Beck's
dredge and transferred by barges, via Newark Slough,
to the plant at Newark. Here, the shells were burned
in a gas-fired rotary kiln 315 feet long by T/2 feet in
diameter. In order to obtain a quality quicklime, the
kiln had a basic refractory lining and was operated at
temperatures as high as 1,600°C (Seaton, 1931, p. 641;
1942. p. 23). Capacity of the lime plant was about
12,000 tons per year. The lime product was reported
to contain less than 0.5% SiO,, around 0.2% Fe,()„
0.2% A120, and about 1.0% MgO. A detailed discus-
sion of the reaction of quicklime with bittern and
other processing data are given by Seaton (1942).
From 1947 to 1968, magnesian lime made from cal-
cined dolomite was used instead of high-calcium lime
to take advantage of the magnesium available in dolo-
mite. The dolomite was obtained from the company's
Westvaco deposit in San Benito County (see Westvaco
deposit under Gabilan Range District) and calcined at
the Newark plant until operations ceased in August
1968.
Other references: Logon, 1947, p. 205; Davis, 1950, p 298-300, Ver
Planck, 1957, p. 319, 322; Bowen and Gray, 1959, p. 37; Goldman, 1967,
p. 24-25.
Ideal Cement Company (Pacific Port land Cement
Company). Ideal Cement Company (420 Ideal Ce-
ment Building, Denver, Colorado 80202) owns and
leases about 35,000 acres of tide and submerged land
in south San Francisco Bay. Large shell deposits w ith-
in this area provide the principal raw materials used
at the company's cement plant located at the Port of
Redwood City.*
• Ideal Cement Company ceased shell dredging operations and cement manu-
facture at its Redwood City plant at the end of 1970 On November 20.
1970. the company announced plans to close the plant hecausc of the high
capital cost of bringing the old and inefficient plant up tu air pollution
control standards set by the State of California (Plans to close the com-
Pacific Portland Cement Company constructed a
portland cement plant at Redwood City in 1924 — ap-
parently to supplant the production from its Cement
Hill plant in Solano County, which was largely im-
porting limestone. It was planned to Utilize oyster
shells and associated mud of San Francisco Bay as a
basic resource at the new plant. Control of the princi-
pal shell deposits of San Francisco Bay was attained
when the cement company acquired the holdings of
the Morgan Oyster Company. The latter company not
only owned a large acreage of oyster beds on both
sides of the Bay between Millbrae and Alviso, but also
leased 4,730 acres from the State of California in 192 3
for the purpose of dredging shells. This lease also was
taken over by Pacific Portland Cement Company. In
1958, the lease expired and a new renewable lease
(Public Resources Code 1850.1) was issued to Ideal
Cement Company (successor to Pacific Portland Ce-
ment Company in 1952) for the same area. The lease
area is situated just north of the San Mateo Bridge
causeway in T. 3 S., R. 3 W., T. 4 S., R. 3 W., and T.
4 S., R. 4 W., M.D. The oyster shell deposits so ac-
quired have been the sole source of lime since 1925,
w hen production began, and the mud associated w ith
the shells has provided the principal source of silica,
alumina, and iron oxide.
Since the expansion of the plant in 1927, when ce-
ment production capacity was raised to 5,000 barrels
per day, there has been no extensive expansion of the
Redwood City plant. However, certain plant changes
between 1927 and 1966 have increased production
capacity about 40%. By assuming that production has
been close to capacity and that shells are the sole
source of lime in cement manufacture, it is estimated
that approximately 2 5 million tons of shell (excluding
mud) have been produced since 1925. Practically all of
this was used to manufacture cement, although small
amounts of shells were washed and processed consist-
ently from 1927 to 1950 for use in soil conditioning
and livestock feed. The latter products were marketed
under the "Fmpire Brand" name. It is further estimat-
ed that at least 6 to 7 million tons of mud was produced
with the shells during 1925-1967. Most of the mud
produced was used in the manufacture of cement.
Land controlled by Ideal Cement includes most of
the shell deposits of southern San Francisco Bay,
shown in figure 2 and described above. All of Ideal's
recent production and perhaps most of the past pro-
duction has come from a 4- to 15-foot thick shell layer
in the vicinity of the San Mateo Bridge causeway (Sto-
ry et al., 1966, p. 48). Shells and associated soft bay
mud ( si It y clay) are obtained by one of two dredges
(one is kept on standby), each of w hich is fitted w ith
a 15- or 16-inch suction pipe and cutter head (Davis,
panv's San Juan BautiSDJ plant, announced concurrently, were later re-
scinded ) It was planned to continue to use the facility as a distribution
terminal for cement manufactured at Ideal's new cement plant in Seattle.
Washington
32
California Division of Mines and Geology
Bull. 197
1955, p. 416). Shells were dredged north of the San
Mateo Bridge causeway during the 1960s (see figure
2). Dredging is conducted by making successive
"passes" along the cut face of a shallow bench. A
bench is thus formed and worked shoreward to the
east. Steel barges are loaded with about 700 tons of
unwashed shells and mud and towed to the Redwood
City plant by tugs. A clamshell bucket and overhead
crane unload the shells and stockpile them on the dock
adjoining the plant. Analyses of the unwashed and
washed shells are given in table 7. Excessive mud is
removed from the shells by washing in a screw clas-
sifier, if necessary, but most of the mud is used in
cement manufacture. The slurry also can be "sweet-
ened" by adding washed shells. Washed shells are ob-
tained from Pioneer Shell Company.
Photo 4. One of two shell dredges operated by Ideal Cement Company.
Dredge made successive passes along face of shallow bench cut in shells and
mud. Dredged shells and mud were screened and conveyed to adjacent
barge (700-ton capacity) and towed to cement plant at Redwood City.
Dredging and cement manufacture ceased at the end of 1970. Photo by
Edward E. Welday, 1970.
The shells and mud are ground and blended with
iron scale or iron ores and other ingredients to make
a slurry of proper proportions. This is dewatered and
fed to four gas-fired rotary kilns which operate at tem-
peratures up to 2,800°F. Clinkers, which are less than
an inch in size, are cooled to 250T. The clinkers are
ground with purchased gypsum and stored in silos for
marketing (Bowen and Gray, 1962, no. 8, p. 2). In
addition to iron scale, the company purchases large
amounts of hydrochloric acid, possibly to reduce the
alkalies in the final product. Shale of the Monterey
Formation, obtained from the company's quarry at
Chittenden, Santa Clara County, has been used in the
raw feed since 1965 and at times prior to that. Only
Type I cement is produced due to the high alkali con-
tent of the bay mud used.
About 200 people are employed at the plant, which
has a rated capacity of 2,510,000 barrels of cement per
year. About 90% of the cement is shipped bulk; the
remainder is bagged. Deep-water port facilities enable
the company to ship cement to markets in Oregon and
Washington, although the great bulk of the cement is
transported by truck to local markets.
Other references: Senior, 1929, p. 247-251; Logan, 1947, p. 307-308.
W.B. Ortley Shell Company. This company
dredged and processed small amounts of shells from
San Francisco Bay from 1930 to 1941. Dredging was
done using a rotary pump mounted on a barge. The
shells were barged to a plant near Alviso for drying,
crushing, and screening prior to sale as poultry feed
(Franke, 1930, p. 9; Logan, 1947, p. 312). Location and
nature of the shell deposits worked are undetermined.
Pioneer Shell Company (L.H. Beck; Beck Dredg-
ing Company). The company is owned by Captain
L.H. Beck, 2772 Bromely Road, San Carlos. Captain
Beck dredged shells from south San Francisco Bay
from 1931 to 1947 (or later) under the names L.H.
Beck and Beck Dredging Company, and from 1956 (or
earlier) to the present time (1967) under the name
Pioneer Shell Company. Locations of earlier dredge
grounds are unknown, but dredging in recent years
reportedly has been conducted east of the ship channel
in the vicinity of the San Mateo Bridge, both north
and south of the bridge causeway. Some of the shells
were processed for livestock feed and soil condition-
ing, first at a plant in Alviso and later at the present
plant at 100 "D" Street in Petaluma. Large amounts of
washed shells also were supplied to Ideal Cement
Company, FMC Corporation, Bay Shell Company,
and possibly others.
In June 1962, Pioneer Shell Company obtained
shells from the shallow water area north of the San
Mateo Bridge causeway near the boundary of Ala-
meda and San Mateo Counties (figure 2). The exact
nature of the deposit is not certain but probably con-
sists largely of surficial accumulations of loose shells
associated with soft bay mud. Dredging is conducted
with a suction dredge, 1,500-cubic-yard and 800-cubic-
yard barges, and two tugboats. The tugboats are used
both for dredging and barge transfer. The dredged
shells and associated mud are pumped from the bay
floor to a trommel where bay water is used to free the
shells of mud. The mud and shell fines are wasted
overboard and the cleaned shell is conveyed to an adja-
cent barge. When loaded, the barge is towed to the
company's plant at Petaluma for further processing.
The washed shells consist almost entirely of native
oyster shells (Ostrea lurida Carpenter). Other mol-
lusks (Japanese littleneck clam, bent-nose clam, bay
mussel, and an unidentified ornate gastropod), includ-
ing some live ones, constitute 5% or less of the shells.
A chemical analysis of the washed shells shows
53.07% CaO (sample 3, table 7).
At the Petaluma plant there are dock facilities
where the shells arc unloaded from the barge by
means of a clamshell and stored. The shells are then
dried in a gas-fired rotary drier and sent to a set of
screens for sizing. Some whole- and half-shell sizes are
1978
I IMFSTONI l\ I III C()\s I K \\( ,| s
33
separated and stored for sale, but most of the material
is reduced in size by rolls or in a hammer mill to
obtain "tine" and "flour" products. The four sizes
(w hole shell, half shell, fine, and flour) are sold sepa-
rately or combined as needed — mainly for poultry and
cattle feed. Some shell also is sold for chemical uses
and soil conditioning. The products are sacked and
shipped as far as Seattle. The shell products are mar-
keted as "Conestoga Brand Products" and guaranteed
to contain at least 94% calcium carbonate. Capacity of
the Petaluma plant is not known, but it is reported
that approximately one barge-load ( 1,500 cubic yards)
of shells is processed each week.
In addition to the shells processed in Petaluma,
large amounts of washed shells are barged to the Ideal
Cement Company plant in Redwood City to "sweet-
en" the raw material used to manufacture cement.
References: Logan, 1947, p. 311; Davis and Jennings, 1954, p. 407.
South Bay Dredging Company. * This company is
owned by P.J. Gambetta (Route 1, Box 78, Brent-
wood), who has dredged shells from San Francisco
Bay since 1953 or earlier. He reportedly dredged south
of the Dumbarton Bridge prior to 1960 but, since then,
apparently has relocated to an unspecified area north
of the San Mateo Bridge causeway. Most of the pro-
duction since 1953 has been sold to Bay Shell Com-
pany (which see) for further processing and
marketing. There is no record of production prior to
1953, although there is some indication that Gambetta
may have dredged shells at least as early as 1945 and
may have sold shells commercially.
South Bay Dredging Company uses a self-propelled
suction dredge capable of operating in water as deep
as 10 or 1 1 feet. Dredging is done through two suction
pipes trailing aft while the dredge pushes a 1,000-cu-
bic-yard barge. Shells and associated mud are pumped
as a slurry into two separate trommels measuring
about 4 feet by 20 feet. Washing is effected by salt bay
water sprayed from an axial pipe running the length
of the trommel. Mud and fine shells are washed
through the %- or '/2-inch mesh trommel screen and
washed aft. The coarse shells are pumped as a salt
water slurry to the barge where water and some addi-
tional clay and silt are allowed to drain from the shells
through screened openings. W hen loaded, the barge is
delivered via Alviso Slough to Alviso, where Bay Shell
Company purchases the entire production.
The shells dredged probably occur as thin surficial
deposits associated with soft mud and distributed over
a large irregular area along the east side of the Bav (see
description above and figure 2). A chemical analysis
of the washed shells dredged by South Bay Dredging
Company shows 54.31% and 53.2% CaO (samples 4
and 5, table 7). The shells arc somewhat broken and
slightly abraded, being a maximum of about 2 inches
• The company reported il ceased its shell-dredging activities as of Mav II,
1969
long. They are derived almost entirely from the native
oyster; but a small percentage consists of the Japanese
littleneck clam, bent-nose clam, bay mussel, and other
mollusks, some of which are dredged live.
Photo 5. Self-propelled dredge and barge of South Bay Dredging Com-
pany. Shells and mud were pumped from bay floor through two pipes aft {in
raised position) and washed through two trommels before being pumped
through pipe (fore) into 1 ,000-cubic-yard capacity barge (left). Company
ceased operations in 1969.
San Mateo Creek deposits. Location: Sec. 18, T. 4
S., R. 5 VV., M.D., 3 miles southeast of Rockaway Beach
(Pacifica); San Mateo 1 5-minute quadrangle. Owner-
ship: City and Countv of San F rancisco Water Depart-
ment (1962).
Four discontinuous masses of F ranciscan limestone,
extending 3,500 feet northwestward across the divide
between San Pedro and San Mateo Creeks, are shown
by Darrow (1963, plate 1). The largest mass has max-
imum dimensions of 1,000 feet by 350 feet and consists
largely of light-gray, dense limestone interbedded
with chert. The indicated size of this body is ques-
tioned because only scattered outcrops were observed
during a cursory examination in May 1962. However,
vegetation tends to obscure the extent of the deposit
and a positive evaluation was not possible. According
to Darrow, there are several smaller limestone lenses
in sec. 20 a mile to the southeast. No quarries or other
improvements were seen, although lrelan (1888, p.
534) states that limestone occurs "at the headwaters of
San Mateo Creek, where lime was formerly burned."
Skyline (Tyson) deposit. Location: S'/< cor. sec. 12
(proj.), T. 5 S., R. 5 W., M.D., 5 miles west of Belmont;
San Mateo 15-minutc quadrangle. Ownership: City
and County of San Francisco Water Department
( 1964).
The Skyline deposit lies just west of Skyline Boule-
vard and half a mile southwest of the spillway of Crys-
tal Springs Reservoir. It is not certain when this
deposit was first opened, but W. O. Tyson (Logan,
1947, p. 309) was one of the early operators in 1945 and
1946. Although the operator in 1948 is not identified,
W alker (1950b, p. 7) reports that production at the
Skyline quarry was about 1,500 tons per day. From
34
California Division of Minks and Geology
Bull. 197
about 1952 to early 1962, the operator was Skyline
Materials, Inc. (Howard E. Marks), of Belmont. That
company produced large amounts of crushed rock un-
til their lease expired. Reportedly, the City of San
Francisco considered the quarry operation a threat to
the quality of water stored for domestic use in Crystal
Springs Reservoir.
The deposit consists of limestone and related rocks
of the Franciscan Formation. It is exposed over a
northwest-trending area at least 1,500 feet long by a
maximum of 350 feet wide. Additional exposures of
limestone 1,500 and 3,000 feet to the northwest in sec.
12 may be a continuation of the deposit, but interven-
ing vegetation and soil cover prevent a definite corre-
lation. Weathered volcanic rock of the Franciscan
Formation flanks the deposit on both sides (Lawson,
1914, map; Davis, 1955, p. 437). Faulting has severely
crushed and disrupted the deposit, causing the rock to
be highly fractured and obscuring the structure.
The limestone is typically of two basic types: 1)
light gray, fine grained, and foraminiferal; and 2) dark
blue gray, fine crystalline, and bituminous. Chert is
commonly interbedded but appears to be less preva-
lent than usual for Franciscan limestone deposits. One
representative sample of material collected from the
'/2-to 1-inch stockpile in 1962 contained 15 to 20%
chert. Greenstone and possibly other rock types are
present in small amounts as interbeds or in-faulted
material. The only available chemical analysis, from a
"70-foot part of the stratigraphic section", is given by
Walker (1950b, table 2) as 43.76% CaO, 0.29% MgO,
1.95% A1203, 0.33% Fe,0„ and 18.74% Si02. Devel-
opment consists of a quarry perhaps 1,200 to 1,500 feet
long and 200 to 400 feet wide with a maximum face of
100 feet on the southwest and 30 feet on the northeast.
Operation of the quarry is described by Davis (1955,
p. 437-438) . The last operator, Skyline Materials, Inc.,
produced crushed and screened rock mainly for road
base materials, bituminous and concrete aggregates,
and drain rock. In May 1962, the crushing-screening
plant was idle. Total production for the Skyline
deposit is probably close to 3 million tons. The extent
of the limestone reserves cannot be determined until
the depth and the continuity of the deposit to the
northwest are explored.
Spring Valley Ridge deposits. Location: SE1/ sec.
19 and E'/2 sec. 29, T. 4 S., R. 5 W., M.D., 4 miles
southwest of Millbrae; San Mateo 1 5-minute quadran-
gle. Ownership: City and County of San Francisco
Water Department (1962).
Darrow (1963, plate 1) shows several small- to me-
dium-sized lenses of Franciscan limestone along
Spring Valley Ridge. Most of the deposits lie at the
southeast end of the ridge near Pilarcitos Lake (Reser-
voir), mainly in E'/2 sec. 29. The largest deposit here
is shown by Darrow to be a maximum of 1,200 feet
long by 400 feet wide. It consists of highly fractured
light- and dark-gray limestone with notable amounts
of interbedded chert. It is exposed through at least 150
feet of relief at the top of the ridge and contains re-
serves of close to 30,000 tons of limestone and chert
per foot of depth. Several small limestone deposits
nearby have not been examined. Another deposit, cen-
tering in SE'/i SE'/i sec. 19 about a mile to the north-
west, is situated just southwest of the ridge crest.
Darrow shows the deposit to be a lens half a mile long
by a maximum width of 300 feet. Only scattered lime-
stone debris was observed in the north part of the
indicated lens, and the deposit was not evaluated fur-
ther.
The only development is a quarry with estimated
dimensions of 120 feet by 40 feet and a maximum
depth of 10 feet in the large lens in sec. 19. Approxi-
mately 2,000 tons of rock have been excavated recent-
ly, apparently by the San Francisco Water
Department as a local source of road material.
Westvaco Chemical Division, Food Machinery and
Chemical Corporation (Westvaco Chlorine Products
Company; California Chemical Corporation) . This
company, now known as Inorganic Chemicals Divi-
sion, FMC Corporation, formerly (1931 to about
1950) purchased shells from Beck Dredging Company
(see Pioneer Shell Company) and manufactured lime
at Newark for chemical use and commercial sales (see
San Francisco Bay Shell deposits, FMC Corporation).
The company quarried dolomite for use in the produc-
tion of magnesium compounds at its Newark plant,
until that plant ceased operations in August 1968 (see
Westvaco deposit under Gabilan Range district).
Wiedemann deposit. Location: SE'/4 sec. 20 and
SW'/4 sec. 21, T. 2 S., R. 1 W., M.D., 2/2 miles south of
San Ramon; Livermore 1 5-minute quadrangle. Own-
ership: Fred Wiedemann, Norris Canyon Road, San
Ramon (1962).
A 30- to 70-foot-thick lens of light-brown limestone
extending west-northwest over a length of a third of
a mile is reported on the northeast flank of Wiede-
mann Hill (Hall, 1958, p. 22, map). The west end of
this lens was examined in November 1962 and found
to consist of heavy beds of sandy coquina and fossilif-
erous sandstone. The beds are steeply dipping, up to
10 or 15 feet thick, and are interbedded with sandstone
of the Briones Formation (Miocene). The carbonate
rocks appear to be too impure to be of economic value.
Unnamed deposit (near Sunol). Location: Sec.
22, T. 4 S., R. 1 E., M.D., 2'/2 miles southeast of Sunol;
Livermore 1 5-minute quadrangle. Ownership: Not
determined.
A large Pliocene "caliche" deposit is shown and
described by Hall (1958, map, figure 2) as a mappable
unit a mile long by a third of a mile wide and as much
as 200(?) feet thick. A smaller deposit also is shown to
the southeast. The "caliche" is described as white,
commonly containing yellowish-gray siliceous inclu-
sions.
1978
I SI ()\| i\ i in Coasi K \\< .1 s
35
SANTA CLARA DISTRICT (B-4)
This district covers the limestone deposits in Santa
Clara County and in southernmost San Mateo
County. Roughly 40 million tons of limestone have
been produced in the district since 1864, when Guada-
lupe Lime Companv commenced operations. Howev-
er, only small amounts were produced prior to
1939 — mainly for lime and for beet-sugar refining.
Since 1939, all of the limestone produced in the dis-
trict has come from the Permanente deposit. Most of
this was used in manufacturing cement; but a substan-
tial quantity of the more siliceous stone has been sold
as crushed rock and some high-quality limestone has
been sold for beet-sugar refining.
Nearly all of the limestone deposits in the Santa
Clara district are part of the Franciscan Formation
and are Cretaceous in age. These deposits are situated
on the northeast flank of the Santa Cruz Mountains.
The Franciscan limestone occurs as numerous discon-
tinuous lenses and masses that form three distinct and
separate belts lying west of San Jose, southeast of Los
Gatos, and south of Gilroy. Distribution of these lime-
stone bodies is shown by Allen (1946, plate 1), Walker
(1950b, plate 1), Bailey and Everhart (1964, plate 1),
and Dibblee (1966b). Because numerous chert in-
terbeds occur with the limetone, few deposits have
been worked commercially. However, by selective
quarrying and hand sorting, some high-grade lime-
stone has been obtained at the Permanente, Los Gatos
Lime Company, Guadalupe Creek, and other deposits
for use in sugar refining and lime manufacture. With
the exception of the Permanente deposit, none of the
Franciscan limestone deposits appears to be sufficient-
ly large or pure for industrial use. Many, however,
may be useful as local sources of crushed rock.
Cummings et al. (1962, p. 192) describe lenses of
limestone up to 1,000 feet long and 100 feet thick in the
Mindego Formation (Oligo-Miocene) in southern
San Mateo County, but there has been no commercial
production from any of them.
Brecciated Eocene limestone, associated with Qua-
ternary caliche or calcareous tufa, also was used in
limited amounts (see Bernal deposit); but such occur-
rences no longer appear to be of economic interest.
Also, some Holocene shells may have been dredged
from the southern tip of San Francisco Bay (see San
Francisco Bay Shell deposits under San Francisco Bay
district).
The only active limestone quarry in the Santa Clara
district is at the Permanente deposit, operated by Kai-
ser Cement and Gypsum Corporation. This and other
deposits and operations are described alphabetically
below.
Baldv Rvan deposits. Location: Sec. 13 (proj.),T.
9 S., R. 1 E. and sec. 18, T. 9 S., R. 2 E, M. D., 5'/2 to
6 miles southwest of Coyote; Los Gatos 15-minute
quadrangle. Ownership: Not determined.
Several small to moderate-sized bodies of limestone
of the Franciscan Formation form a group extending
1 '/2 miles westward from Baldv Ryan (Longwall)
Canyon to Fern Peak (Bailey and Everhart, 1964, plate
1). The largest and most accessible deposits lie at the
extremities of the group. The large deposit to the west
at Fern Peak is 1,000 feet long by a maximum of 75 to
100 feet wide. To the east in Baldv Rvan Canyon is a
similarly narrow deposit 1,700 feet long. This deposit
contains an unusual oolitic limestone that is exposed
conspicuously. Bailey and Everhart (1964, p. 23) de-
scribe the oolitic limestone as "dull battleship gray,
and the purest consists almost entirely of oolites about
2 mm in diameter, embedded in a matrix of smaller
oolites averaging about 0.1 mm in diameter." Less
pure varieties, which grade into tuffs and shales, are
reported to be more common. A chemical analysis by
A. C. Vlisidis (Bailey and Everhart, 1964, p. 24) of the
oolitic limestone indicated 0.91% SiO,, 0.61% A120„
0.30% Fe20„ 0.77% MgO, 55.11% CaO, 0.10% Ti02,
0.31% P20„ 0.01% MnO and 42.24% C02.
Bailey and Everhart ( 1964, p. 24) consider the oolit-
ic limestone to offer "good commercial possibilities"
because of the virtual absence of chert lenses. Howev-
er, all of the limestone bodies of the Baldv Ryan drain-
age lie within a broad shear zone and are apt to be less
continuous than indicated on Bailey and Fverhart's
map (plate 1).
Other reference: Bailey, Irwin, and Jones, 1964, p. 72-73.
Bernal deposit. Location: SE1/ sec. 19 (proj ), T.
8 S., R. 2 E., M. D , 1 mile northwest of Coyote Peak
and 3 miles west of Coyote; Los Gatos 1 5-minute quad-
rangle. Ownership: Mr. Gomez, Hollister(r) (1962).
Fragmental limestone and associated caliche or cal-
careous tufa ("marl") were utilized intermittently
from 1915 to 1938 for beet-sugar refining and agricul-
tural purposes. The deposit apparently was opened by
Spreckels Sugar Company, which shipped a few thou-
sand tons of limestone around 1915 to one of their
refineries (Huguenin and Costello, 1920, p. 186). Un-
der the ownership of Pedro A. Bernal, the California
l.ime Marl Fertilizer Company produced roughly 10
to 20 thousand tons of soft "marl" for agricultural use.
At the quarry, a coarse breccia of fragmental Eocene
limestone is imbedded in varying amounts in a soft
matrix of caliche or impure calcareous tufa. The
deposit, which ranges from 5 to 15 feet thick or more
overlies sheared sandstone at the south side of the
quarry. Sandstone fragments and other impurities
also are present in the carbonate matrix. It seems like-
ly that the deposit is the result of landsliding or fault-
ing in association with the surficial deposition of
calcium carbonate. The Eocene age of the hard lime-
stone is based on its abundant fossil debris ( Bailey and
Everhart, 1964, p. 69-71). It is gray to yellowish tan,
dense to slightly vuggy, fine grained to medium crys-
talline, and locally is either sandy or argillaceous(P).
A typical sample of the hard limestone, analyzed by
$6
California Division of Mines and Geology
Bull. 197
Lydia Lofgren of the California Division of Mines and
Geology in 1962, showed 53.07% CaO, 85% MgO,
2.32% Si02, .40% A120„ .40% Fe20„ .01% P2Os, and
42.55% ignition loss.
The soft matrix material is off white to vellowish-
and reddish-brown, porous, impure calcium carbon-
ate. This no doubt is the "marl" quarried and pulver-
ized for agricultural use.
The deposit is exposed over a small area as low,
scattered outcrops of hard limestone separated widely
by soil. When examined in July 1962, development
consisted of a shallow, irregularly benched quarry 200
to 300 feet in diameter. There has been no recent activ-
ity and future possibilities appear to be limited.
Bailey and Everhart (1964, plate 1) mapped the
deposit as an east- west lens, 500 feet long by 125 feet
in maximum width. They show three other lenses in
SE1/ sec. 19. The largest of these, lying 600 feet
northeast of the Bernal deposit, measures 1,100 feet by
200 feet. It was developed by a trench 100 feet long by
1 5 feet wide, which exposes 8 feet of limestone breccia
and caliche similar to that at the nearby quarry. The
map shows several other deposits of Eocene limestone
to the west. The largest of these, in sec. 20, T. 8 S., R.
2 E., is nearly half a mile long. It is exposed only as
scattered limestone fragments in heavy soil and is not
believed to represent a deposit of significant size or
purity. The Eocene deposits examined in the Santa
Teresa Hills have insufficient exposures to indicate
much commercial potential. Indeed, two of the depos-
its are brecciated and impure where they were quar-
ried.
Other references: Franke, 1930, p. 9; Logan, 1947, p. 311-312; Davis and
Jennings, 1954, p. 364.
Calero deposit. Location: Near center sec. 8
(proj.), T. 9 S., R. 2 E., M. D., 4 miles southwest of
Coyote; Los Gatos 15-minute quadrangle. Ownership:
E. M. Fellows (estate), 23201 McKean Road, Morgan
Hill (1965).
This deposit lies a little more than a mile south of
Calero Reservoir in a small valley a mile west of
McKean Road. It is exposed as an arcuate, northwest-
trending body of Franciscan limestone 1,800 feet long
by an average of 200 feet wide (Bailey and Everhart,
1964, plate 1). The Calero deposit consists mainly of
fine-grained to medium-crystalline, light- to dark-
gray, thinly bedded, bituminous, locally brecciated
limestone, commonly with interbeds of black chert.
At the northwest end of the body, light-dove-gray,
pink, and brownish-red varieties of limestone were
observed (July 1962). Most beds exposed in the creek
dip moderately northeast and southwest, although
other dip directions are indicated at the extremities of
the body. Abrupt changes in attitude, plus brecciated
beds, suggest that the limestone body is broken by
faults.
Judging from exposures near the quarry, the se-
quence of limestone beds is probably at least 50 feet
thick. If an average thickness of 50 feet is assumed,
available reserves of limestone and chert would be in
the order of a million tons. Future potential of the
deposit is probably limited to crushed rock uses due to
the dispersion of chert interbeds throughout the lime-
stone.
A single quarry situated in the middle of the deposit
on the north bank of the creek was worked prior to
1937, when E. M. Fellows acquired the property. The
quarry is 75 by 20 feet in plan with a 30-foot face. The
use of the quarried rock and other details of develop-
ment are unknown. In 1962 the owner reported that
the deposit was test drilled, but the results are un-
known.
Castro Valley deposits. Location: Sec. 15 (proj.),
T. 11 S., R. 3 E., and sec. 30, T. 11 S., R. 4 E., M.D.,
3 to 4 miles southwest and south of Gilroy; San Juan
Bautista 15-minute quadrangle. Ownership: Mainly
Castro Valley Ranch (c/o H. S. Chase, Santa Bar-
bara), Sargent Ranch, and Shoemaker (Bloomfield)
Ranch (1963).
Numerous lenses of limestone, associated with
other sedimentary and volcanic rocks of the Francis-
can Formation, are shown on the northeast flank of
the Santa Cruz Mountains by Allen (1946, plate 1).
The lenses lie in two principal groups centering in S'/2
sec. 15 (proj.) and 3 miles to the southeast in and near
SW/4 sec. 30. Some of these deposits were examined
briefly in July 1963. Scattered limestone bodies also lie
to the north and east (Allen, 1946, plate 1).
The deposits in sec. 15 consist of a west-trending
series of detached lenses and masses. The largest is a
sinuous lens, roughly 1,500 feet long by 150 feet wide,
that dips north into the hill. On hill "1722", a faulted
mass 900 feet long by a maximum of 200 feet wide
appears to merely cap the ridge and may be relatively
thin. In sec. 30, the limestone bodies trend more to the
northwest and are smaller than shown by Allen. The
limestone observed in each area is generally dark gray,
fine crystalline, bituminous, well bedded to platy, and
somewhat siliceous. Other types of limestone are light
gray or even dark gray mottled with white. All of the
limestone is abundantly associated with thin interbeds
of chert. Variable attitudes and common brecciation
features reflect the widespread faulting that has dis-
turbed and broken the many lenses. Some of the larger
faults are shown by Allen (1946, plate 1).
Two or three tiny quarries, from which only a few
tens of tons of material were removed, were developed
in S'/2 sec. 30 many years ago for an undetermined
purpose. A chemical analysis by Matti Tavela of the
Division of Mines and Geology of typical mottled
(brecciated), bituminous limestone from a quarry in
SW1/, sec. 30 showed 3.0% Si02, 0.60% Al20„ 0.19%
Fe20„ 0.27% MgO, 51.8% CaO, 0.14% PX), and
43.0% ignition loss. Reserves of limestone may aggre-
gate several million tons, but none of the individual
masses appears to contain more than a few hundred
1978
LlMlsioM l\ I III Co\si Rwt.ls
37
thousand tons of available limestone. The largest
masses lie in SW1/ sec. 15 and on hill "1722" in SE1/
sec. 15. Future development would appear to be lim-
ited to supplying local markets with crushed rock.
Clark Ranch deposit. An undeveloped deposit of
"hvdraulic limestone" is reported 7 miles east of Ma-
drone (Watts, 1890, p. 619; Logan, 1947, p. 312). Its
exact location is unknow n.
Guadalupe Creek (Guadalupe Lime Company)
deposits. Location: Near SW'/4 S\V'/4 sec. 29 (proj.),
T. 8 S., R. 1 E., M. D., 5 miles east of Los Gatos; Los
Gatos 15-minute quadrangle. Ownership: Not deter-
mined (1962).
Several small deposits of cherty limestone of the
Franciscan Formation lie 1,000 feet south of Guada-
lupe Creek. These were quarried by Guadalupe Lime
Companv as a source of lime from about 1864 to 1890
or a little later (Irelan, 1888, p. 543; Watts, 1890, p. 619;
Crawford, 1894, p. 349). The limestone was developed
through several small quarries and hauled "by trucks
worked by a gravity pulley" to the kiln 400 feet below
(Irelan, 1888, p. 543). Considerable hand-sorting evi-
dently was necessary to remove the chert from the
limestone. Production during the summer of 1890 was
150 barrels of lime per day (Watts, 1890, p. 619).
There is no record of further production, but there is
some evidence that more recent development work
was carried out in the quarry areas. The Guadalupe
Oeek deposits may have been part of the holdings of
San Jose Cement Company (which see).
The small, detached bodies of limestone that have
been quarried form a closely spaced, northwest-trend-
ing group lying just southeast of the fourth "hairpin"
curve of the paved access road. Other small limestone
masses are shown to the southeast and northwest of
that group by Bailey and Fverhart (1964, plate 1) but
are undeveloped. Altogether, the limestone extends
discontinuously for 4,000 feet. Where developed, the
deposits are largely covered with talus and quarry
debris consisting mainly of light-gray, dense, fine-
grained, sometimes siliceous limestone and gray to
black, thin-bedded chert. Locally, dark-gray, white-
mottled, crystalline limestone is present. According to
Irelan (1888, p. 543), "dark-colored bituminous lime-
stone" also is found, but such material was not ob-
served during a brief visit in May 1962. The degree of
fracturing, as well as the presence of secondary calcite,
suggests the deposits may be broken by faults.
The deposits are developed by several small quar-
ries over a length of 900 feet. Quarry development is
too irregular to estimate total production accurately,
but probably it is less than 50,000 tons.
Limestone reserves cannot be accurately deter-
mined without better exposures and some drill data,
but available reserves do not appear to be large. Be-
cause of the presence of chert beds within the lime-
stone, the deposit is useful chiefly as a local source of
crushed rock.
Guadalupe Reservoir deposits. Location: Near
SW'/4 sec. 33 (proj.), T. 8 S., R. 1 E., M. D., 6 miles
east-southeast of Los Gatos; Los Gatos 15-minute
quadrangle. Ownership: Not determined (1962).
A C-shaped mass of limestone of the Franciscan
Formation was mapped by Bailey and Fverhart ( 1964,
plate 1) just west of Hicks Road at the upper end of
Guadalupe Reservoir. The deposit is shown to be a
maximum of 150 feet wide and 1,600 feet long. Bed-
ding attitudes are not consistent with the mapped dis-
tribution of limestone, and it is likely that this
modest-si/.ed deposit is broken by faults and is possi-
bly discontinuous. Small bodies of limestone also are
shown by Bailey to lie nearby. The limestone is re-
ported by Bailey (1962, personal communication) to
be typical of the Franciscan Formation and it contains
thin chert interbeds. There has been no commercial
development, although some prospecting was done at
the small limestone body near Hicks Road.
Kennedy Road deposit. Location: S\V'/( sec. 24, T.
8 S., R. 1 W., M. D., 3 miles east of Los Gatos; Los
Gatos 15-minute quadrangle. Ownership: Not deter-
mined (1962).
A northwest-trending lens of Franciscan limestone
1,300 feet by a maximum of 1 50 feet is shown by Bailey
and Everhart ( 1964, plate 1 ) . The southeast end of the
lens, where crossed by Kennedy Road, was examined
briefly in July 1962. Here, the body consists of a some-
what faulted sequence of beds that dips moderatelv
south and is about 100 feet thick. The upper half con-
sists of typical light-gray, dense, foraminiferal lime-
stone with thin chert interbeds. Limestone in the
lower part is interbedded or otherwise mixed with
sandstone and volcanic rock of the Franciscan Forma-
tion. The deposit is partly brecciated and recemented
with calcite.
The deposit is undeveloped; it appears to be suitable
mainlv for crushed rock purposes. Maximum avail-
able reserves are probablv less than 500,000 tons of
limestone and associated rocks
Los Gatos Lime Company deposit (Ellis; Douglas
Ranch). Location: SW'/4 NW'/4 sec. 27 (proj.), T. 8
S., R. 1 W., M.D., 1 mile southeast of Los Gatos; Los
Gatos 15-minute quadrangle. Ownership: Lloyd Es-
tate, c/o Tal and John Llovd, 16140 Cvpress Way, Los
Gatos (1962).
Los Gatos Lime Company quarried limestone
between 1886 and 1890, and most of it probably came
from property owned by J. E. Ellis (formerly Douglas
Ranch) . The limestone was hauled 2 miles to a kiln in
Los Gatos where lime was manufactured (Watts,
1890, p. 619). Some limestone also was sold for sugar
refining (Irelan, 1888, p. 545-546). Several thousand
tons of limestone shipped for sugar refining from the
Los Gatos area in 1938 by Basic Limestone Products
Companv mav also have come from this deposit (Lo-
gan, 1947, p. 312).
5S
California Division of Mines and Geology
Bull. 197
The deposit consists of three small limestone masses
that extend south westward for 1,500 feet. The largest
of these is shown by Bailey and Everhart (1964, plate
1) to be faulted and to cover an irregular, northeast-
trending area 600 feet by 275 feet in maximum dimen-
sions. It consists of typical Franciscan limestone and
moderate amounts of thin chert interbeds. At the
quarry, the strata dip 20°- 3 5° S and have an estimated
exposed thickness of 30 feet. Here the limestone varies
from fine grained, light gray, dense, and foraminiferal
to dark gray, fine crystalline, and bituminous. Sand-
stone and volcanic rocks of the Franciscan Formation
are in contact with the deposit on the north.
When examined in July 1962, the main limestone
mass was developed by an irregular quarry 250 feet by
100 feet. It had been worked by two benches through
a relief of about 80 feet. Roughly 10,000 to 20,000 tons
of rock had been removed. Vegetation indicates the
quarry has not been worked for at least 20 years. Two
other quarries are indicated 800 feet and 1,200 feet to
the southwest in a small lens (Bailey and Everhart,
1964, plate 1). These quarries were not examined but
are probably small.
Because the limestone bodies are small and com-
monly contain chert interbeds, future use of the lime-
stone appears to be limited to crushed rock.
Other references: Crawford, 1894, p. 394; Aubury, 1906, p. 82-83; Davis
and Jennings, 1954, p. 364.
Lyndon deposits. Location: S'/2 sec. 28, T. 8 S., R.
1 W., M. D., 1 mile south of Los Gatos; Los Gatos
15-minute quadrangle. Ownership: Guadalupe Col-
lege (?), Los Gatos (1962).
The Lyndon deposits lie on St. Josephs Hill, mainly
in NW'/J SE'/i sec. 28. As mapped by Bailey and Ever-
hart (1964, plate 1), the deposits consist of a number
of small lenses of Franciscan limestone extending over
an area half a mile long by 1,000 feet wide. The largest
lens is about 700 feet long and a little more than 100
feet wide at its maximum. It consists of light-gray,
fine-grained, foraminiferal, somewhat siliceous lime-
stone with lesser amounts of fine crystalline, dark-
gray, bituminous limestone. Chert interbeds are com-
mon throughout the limestone and may comprise a
quarter of the deposit. The strata show variations in
attitude and probably are faulted. The deposit was
developed by a narrow hillside quarry about 200 feet
long with a 20-foot face (visited July 1962). Produc-
tion, which amounted to only a few thousand tons,
was made many years ago judging from the considera-
ble plant growth. A small quarry, 700 feet to the south-
east, exposes another small lens. It is not known who
worked these deposits, but it may have been the Los
Gatos Lime Company (which see).
Below the Franciscan limestone outcrops, Eckel
( 1933, p. 356, 359) noted a large deposit of travertine
as much as 30 feet thick. Apparently it is undeveloped.
Other reference: Davis and Jennings, 1954, p. 364, 408.
Mindego deposits. Location: Mainly sees. 7, 18, 19,
T. 7 S., R. 3 W., and sec. 15, T. 8 S., R. 3 W., M. D.,
1 '/2 to 3 miles east, 1 mile west and 8 miles southeast
of La Honda; Half Moon Bay and Ben Lomond 15-
minute quandrangles. Ownership: Not determined.
Thin beds and lenses of limestone are reported in
the Mindego Formation (Oligo-Miocene) at several
localities near La Honda and southeast of that settle-
ment. These deposits are described by Cummings et
al. (1962, p. 192) as follows:
"Some of these are catcarenites overlying volcanic strata. Many
are bioclastic in origin and consist largely of fragments of small
pelecypods and bryozoa. For example, along Waterman Creek in
sec. 15, T. 8 S., R. 3 W., one of these limestone lenses is more than
1,000 feet long and nearly 100 feet thick and is composed chiefly
of broken and compacted oyster shells. Other limestones occur
neor the summits of Mindego and Langley Hills and in San Gre-
gorio Creek in the vicinity of Redwood Terrace."
These same deposits were described as "limestone in-
clusions" and "clastic dikes" of Eocene age by Bran-
ner et al. (1909, p. 3, 8-9, map).
None of these occurrences is known to be of eco-
nomic value, although the Waterman Creek deposit
appears large enough to warrant further investiga-
tion. The chemistry of the limestone is not known,
except that tuffaceous debris is reported to be com-
mon.
Monte Bello Ridge deposits (including Bond, Win-
ship, Black Mountain). Location: E'/2 T. 7 S., R. 3
W., and SW'/4 T. 7 S., R. 2 W., M. D., 5 to 8 miles south
and southwest of Los Altos; Palo Alto 1 5-minute quad-
rangle. Ownership: Multiple — includes Kaiser Ce-
ment and Gypsum Corp., National Realty Co., Mary
I. Crocker, Winship Estate, G. F. and A. Morrell, Em-
met Burns, and many others (1962).
The Monte Bello Ridge deposits form a group of
numerous, small to medium-sized limestone bodies
that extends southeastward for 71/, miles from a point
west of Page Mill Road in NW1/, sec. 10., T. 7 S., R. 3
W., to Stevens Creek near S'/4 cor. sec. 33, T. 7 S., R.
2 W. The deposits lie on the northeast side and within
l'/2 miles of the San Andreas fault, which obliquely
truncates the northwest end of the group. Part or all
of the deposits have been mapped by several geolo-
gists, but the only published maps are bv Walker
(1950b, plate 1) and Dibblee (1966b). Part of Dib-
blee's map is reproduced in figure 3. Included in the
Monte Bello Ridge group of deposits are the proper-
ties of Bond (Franke, 1930, p. 9) and Winship
(Huguenin and Costello, 1920, p. 185), as well as most
of the deposits on Black Mountain (Permanente
deposit excepted). There has been no commercial de-
velopment of the limestone although considerable
trenching and core-drilling was conducted within 1 '/2
miles of Black Mountain by Permanente Cement
Company (now Kaiser Cement and Gypsum Corpo-
ration), mainly about 1945.
1978
LlMKSTONF IN 1 HI C().\SI R.VNCFS
2 Miles
Limestone with chert interbeds
Fronctscon Fm
Inclined Vertical Overturned
Strike and dip of beds
Figure 3. Map of Permanente and Monte Bello Ridge limestone deposits.
The limestone on Monte Hello Ridge occurs as len-
ticular, discontinuous masses in a thick sequence of
volcanic and sedimentary strata of the Franciscan For-
mation. The strata dip predominantly northeast but
in many places are vertical or overturned to the south-
west (Dibblee, 1966b). Evidence of faulting is preva-
lent throughout the area, and some minor faults offset
some of the limestone lenses. The limestone every-
where is associated with thin chert interbeds. Most
lenses of the limestone and chert are less than 50 feet
thick and seldom as thick as 100 feet. However, the
lens in NE'/i sec. 29 is reported to be as much as 200
feet thick and to dip vertically (Dibblee, 1965, oral
communication) . The limestone is typical of the Fran-
ciscan Formation, varying from light gray, fine
grained, and foraminiferal to dark gray, fine to me-
dium crystalline, and bituminous. Silica in chert beds,
as well as distributed interstitially with the calcite,
constitutes the principal impurity. The maximum
grade of selected limestone samples is indicated by
analyses in Franke (1930, p. 9, 10) and Huguenin and
Costello (1920, p. 185). Four analyses (made by Abbot
A. Hanks, Inc., in 1956) of selected samples from the
Burns Ranch in sec. 15 — containing 51.3-54.1% CaO,
0.2-0.5% MgO, 0.8-4.5% Si()2, and small percentages
of Fe203, A1203, and P2C)5— are rather typical of the
Monte Bello Ridge limestone deposits.
Reserves of limestone no doubt aggregate many mil-
lions of tons, but none of the deposits appears to be
very large. Furthermore, many of them dip steeply
into the ridge, thereby limiting the available reserves.
The apparent small size and discontinuous nature of
40
California Division of Mints and Geology
Bull. 197
the deposits has been verified to some extent by drill-
ing and trenching in the vicinity of Black Mountain.
Little exploration has been done elsewhere. Consider-
ing the relatively small size of the deposits and the
presence of chert interbeds, it is probable that the
limestone will be useful only for crushed rock pur-
poses.
Other reference: Logon, 1947, p. 312, 317.
Permanente (Black Mountain) deposit. Loca-
tion: W1/, sec. 17andE'/2sec. 18, T. 7 S , R. 2 W., M. D.,
4 miles south of Los Altos; Palo Alto 15-minute quad-
rangle. Ownership: Kaiser Cement and Gypsum Cor-
poration, 300 Lakeside Drive, Oakland (1965).
The Permanente deposit is situated mainly on a
steep slope on the north side of Permanente Creek, 1 '/2
miles east of Black Mountain. It is by far the largest
limestone body known in the Franciscan Formation
and may contain the largest reserves of any limestone
deposit in the central Coast Ranges. Initial develop-
ment of this deposit apparently began around 1900,
when El Dorado Sugar Company selectively quarried
high-grade limestone for use in beet-sugar refining
(Aubury, 1906, p. 82). Later, Alameda Sugar Com-
pany quarried limestone which was shipped to Alviso,
where it was calcined for use in sugar refining
(Huguenin and Costello, 1920, p. 185). Santa Clara
Holding Company acquired the deposit during the
1920s, but records indicate that they produced lime-
stone (for lime) only in 1934. Large scale production
of limestone began in 1939 when Permanente Cement
Company established a plant to supply 6,800,000 bar-
rels of cement for the construction of Shasta Dam.
Expansion over the years has increased plant capacity
from 21/, million to 8'/2 million barrels of cement per
year. Production of limestone and associated materials
has increased to more than 2 million tons per year.
Most of this has gone to make cement, but significant
amounts of overburden and low-grade limestone are
sold commercially for aggregate and road construc-
tion uses. Until 1951, the company also sold high-
grade limestone for use in beet-sugar refining. In-
creasing percentages of low-grade limestone encoun-
tered in recent years stimulated Permanente Cement
Company to explore ways to beneficiate the lime-
stone. They completed a froth flotation plant in 1962;
and, according to Kleiber and Meisel (1964), this
plant was operating successfully by 1963. In 1964, the
company changed its name to Kaiser Cement and
Gypsum Corporation.
The limestone deposit at Permanente Creek covers
an irregular triangular area having a maximum length
of a mile and a maximum width of two-thirds of a mile
(fig. 3). It is exposed through 800 feet of relief and
may be as much as 700 feet thick in places ( Kleiber and
Meisel, 1964, p. 39). The limestone body, which con-
tains early Late Cretaceous microfossils, is associated
with altered volcanic rocks (greenstone) and sedi-
mentary rocks of the Franciscan Formation. Structur-
ally the limestone body is complicated by faults and
folds, but mainly it dips 25° to 35° SE. Moderate
northeast dips in the south part of the mass indicate
the deposit to be an eastward plunging syncline whose
axial trace lies just north of Permanente Creek.
Internally, the deposit consists of thin beds of light
and dark limestone which tend to occur in mutually
exclusive sequences. Thin layers and lenses of chert
are interbedded in varying amounts with both types
of limestone. A thick sill or flow of volcanic rock, now
altered to greenstone, and a few thin tuff beds also are
present in the quarry area. The stratigraphic relations
of these different beds and sequences is not clearly
understood, as extensive faulting has severely disrupt-
ed the deposit. G. W. Walker (1950b) interpreted the
stratigraphic sequence to consist of an "upper light"
limestone unit, a "blue" limestone unit, and a "lower
light" limestone unit. A more recent interpretation,
based on extensive drill data and chemical analyses,
was given by Donald Towse of Kaiser Cement and
Gypsum Corporation in a paper presented at the
American Institute of Mining, Metallurgical, and Pe-
troleum Engineers, Southwest Mineral Industry Con-
ference, Las Vegas, Nevada, April 24, 1961. According
to Towse, the deposit consists of only two limestone
units — an upper light-colored unit at least 300 feet
thick and a lower dark gray unit at least 200 feet thick.
The light limestone is split near its middle by a 90-foot
thick greenstone sill or flow. These units may be
sliced by two or three thrust faults, causing wide-
spread repetition and omission of strata. Further com-
plexities resulted from later folding and high-angle
faulting.
The light limestone is typically light gray to dove
gray, fine grained, dense, foraminiferal, and well bed-
ded. Light and dark interlayers of chert, 1 to 3 inches
thick, constitute 10 to 50% of the light unit, being
more prevalent near the base. The dark limestone is
blue gray to dark gray but weathers and bleaches to
lighter shades of gray. It is very fine to medium crys-
talline, bituminous, and well bedded to platy. Black
chert interbeds are common but not as abundant as in
the light limestone. Both types of limestone are
strongly fractured.
The chemical grade of the limestone is quite varia-
ble, with high and low grades occurring in both the
light and dark units. The variations in grade are re-
flected to some extent in the bulk analyses presented
in table 8. According to Towse, the dark limestone
averages 87% CaC03 and the light limestone 67%
CaC03, the upper part of the light limestone being the
best quality (also see Bailey, Irwin, and Jones, 1964, p.
70). For purposes of quarry development, three quali-
ties of limestone are recognized by Kaiser Cement and
Gypsum Corporation (Kleiber and Meisel, 1964, p.
39): 1) high grade — consists of dark limestone and
averages 87 to 88% CaC03; 2) medium grade — a mix-
ture of light and dark limestone running 70 to 82%
CaC03; and 3) low grade — mainly extremely cherty,
light-colored limestone containing 55 to70%CaCO3.
1978
LIMESTONE IN TDK COAST RANGES
4]
Table 8 Bulk analyses of limestone from the Permanente deposit, Santa Clara County ( Bailey and Everhart, 1964, table 6).
/ 2 3 4 5 6 7 8 9 10
Sid 29.2}% 18.4% 17.5% 16.7% 15.9%
AljQ, 1.26 1.5 1.4 1.5 1.5
Fe2Oj 0.54 0.7 0.7 0.7 0.7
CaO 38.04 43.3 43.8 44.4 44.9
MgO 0.24 0.3 0.4 0.3 0.4
Loss on ignition ... 3066 34.3 34.7 35.1 35.7
Total 95W 98.5 98.5 98 7 99.1
CaC03 68T 77l T%2 793 802
1. 9. and 10 from Logan, 1947, p. 315.
2~tl obtained from Permanente Cement Co. bv E H Bailev and D L Everhart
15.2%
1.5
0.7
45.4
0.4
36.1
99.3
8L0
13.4%
1.4
0.6
46.4
04
311
993
82~9
11.3%
1.3
0.6
47.8
0.3
3JU
99.6
85J
7.24%
0.60
0.42
50.96
0.04
40.48
99.74
9T39
4.18%
0.66
0.32
52.74
0.05
41.90
99.85
9*67
Normally the low-grade limestone, which is in-
terbedded with the higher grades, would be wasted.
However, by means of differential grinding and froth
flotation, the low-grade rock is sufficiently up-graded
to be blended into the raw feed for cement.
Quarry operations at the Permanente deposit are
conducted by benching, at 50-foot intervals, in one
large pit near the center of the deposit. An older aban-
doned quarry is located in S\\n/t SE'/i sec. 18 at the
west end of the deposit. In 1962, the main quarry
covered an area about 1,800 feet bv 1,500 feet. There
was about 500 feet of relief between the highest face
and the quarry floor, the latter being at an elevation
of 1,350 feet. Quarry control is provided by explora-
tory (rotary) drilling on 100-foot or 100-foot by 200-
foot centers. Deep diamond drilling also is used for
long-range planning.
Normal open-pit operations prevail, with selective
quarrying employed to maintain the proper grades of
limestone. Blast holes are made with air-circulated ro-
tary drills. Ammonium nitrate and oil constitute the
explosive. Some secondary blasting is necessary. Elec-
tric-powered shovels load 45-ton-capacity dump
trucks, which haul to primary crushers at the edge of
the quarry floor. The material is then crushed and
transferred to secondary crushers near the plant via a
4200-foot belt conveyor. After secondary crushing, the
limestone is conveyed to separate stockpiles to await
further processing. Weathered greenstone, obtained
west of the quarry and used to supply the needed
alumina and iron in cement, also is stockpiled here.
Formerly, the alumina-iron oxide fraction was sup-
plied by purchasing laterite produced in Amador
County.
Pholo 6. View to west of large multi-benched quarry at Permanente lime-
stone deposit, 1969. The quarry is developed in chert-bearing limestone
(Franciscan Formation), which is the principal raw material used at the
nearby cement plant. Photo courtesy of Kaiser Cement and Gypsum Corp.
Photo 7. Aerial view of Kaiser Cement and Gypsum Corporation's cement
plant at Permanente in 1969. The plant, which is the lorgest in the west, has
six kilns and an annual capacity of 8,500,000 barrels of cement. Photo
courtesy of Kaiser Cement and Gypsum Corp.
4:
California Division of Mines and Geology
Bull 197
The various raw materials are further crushed,
ground, beneficiated, and blended to make up the raw
feed (slurry). The feed is processed wet in six kilns,
ranging from 444 feet to 454 feet long, to obtain the
clinker. This is later ground with gypsum from Mex-
ico to produce a variety of cement products. In addi-
tion to cement, the operator has produced crushed
rock for use in concrete aggregate and road construc-
tion for many years. Such material has come from
overburden and low-grade limestone. A sand by-prod-
uct, derived as tailings from the flotation circuit, also
is recovered for commercial sales ( Kleiber and Meisel,
1964, p. 44).
Total production of limestone and associated chert
at the Permanente deposit is estimated to be on the
order of 40 million tons. Proved and estimated reserve
figures are not available, but deep diamond-drilling
indicates that reserves considerably exceed past pro-
duction.
Other references-. Franke, 1930, p. 9; Krivari, 1942, p. 374-397; Logan,
1947, p. 313-317; Davis and Jennings, 1954, p. 355-358, 361, 364-366;
Bowen and Gray, 1962, pt. 2, p. 4; Bailey and Everhart, 1964, p. 24.
San Jose Cement (Guadalupe Portland Cement)
Company formerly owned a "deposit of 331 acres of
undeveloped limestone" in sees. 4 and 5, T. 9 S.,
R. 1 E., and sec. 32, T. 8 S„ R. 1 E., M.D. (Franke,
1930, p. 9-10). This property probably included the
Guadalupe Reservoir deposit (which see). The com-
pany lapsed as a corporation in 1936 (Logan, 1947, p.
313).
Snell Ranch deposit. Location: 2'/2NE'/ sec. 28, T.
8 S., R. 1 W., M.D., 1 mile southeast of downtown Los
Gatos; Los Gatos 15-minute quadrangle. Ownership:
J. A. Snell, Foster Road, Los Gatos (1962).
This deposit of Franciscan limestone is shown by
Bailey and Everhart (1964, plate 1) to be an east-west
lens 1,300 feet long by a maximum of 200 feet wide.
Where exposed along Foster Road, the deposit is at
least 25 to 30 feet thick and dips gently to moderately
south. It is composed mainly of dark, fine-crystalline,
somewhat mottled, bituminous, thinly bedded lime-
stone that appears to be brecciated and recemented
with calcite. A chemical analysis by Matti Tavela in
1963 of typical limestone from the quarry showed
1.3% Si02, 0.60% A1203, 0.37% Fe203, 0.35% MgO,
53.9% CaO, 0.10% P2Os and 42.8% ignition loss. Light
dove-gray, fine-grained limestone is present in lesser
amounts. Thin interbeds of dark chert constitute the
main visible impurity.
The deposit was developed by a tiny quarry west of
the road, from which less than 1,000 tons of material
was excavated. The date or purpose of development is
unknown, although it is possible that this limestone
was used by Los Gatos Lime Company (which see).
Wright's Ranch deposit. Location: probably sec.
16 (proj.), T. 9 S., R. 2 E., M.D., 5 miles southeast of
New Almaden mine; Los Gatos 15-minute quadran-
gle. Ownership: Not determined.
"A large and valuable deposit of marble" is de-
scribed by Crawford (1894, p. 394). It is exposed con-
tinuously over an area 60 feet to more than 100 feet
wide and more than 3,000 feet long. The limestone is
usually light gray but occasionally is tinged with red
or brown. Some is nearly white, "but it is mostly
mottled or curiously marked by blotches and streaks
of light shades in the darker crystalline ground-mass."
Crawford indicates the deposit to be of limited devel-
opment, although some stone apparently was quar-
ried.
This deposit probably is included in the mile-long,
northwest-trending group of limestone lenses mapped
as part of the Franciscan Group by Bailev and Ever-
hart (1964, plate 1) in sec. 16 (pro'j.), by T. 9 S., R. 2
E. The largest of these lenses is shown to be a thin,
sinuous body less than 100 feet thick, 1,200 feet long,
and dipping steeply to the southwest.
Other reference: Logan, 1947, p. 317.
Unnamed deposits (near Chesbro Reservoir).
Location: Approx. sec. 23 (proj.), T. 9 S., R. 2 E.,
M.D., north of Chesbro Reservoir and 3 miles west of
Morgan Hill; Morgan Hill 15-minute quadrangle.
Ownership: Not determined.
Bailey and Everhart (1964, p. 21) mention the oc-
currence of limestone in the Franciscan Formation 2
miles south of the mouth of San Bruno Canyon. By
way of comparison, they state that the "limestone
crops out in more continuous exposures" than in the
adjacent Santa Teresa Hills quadrangle to the west
(see Bailey and Everhart, 1964, plate 1). Some lime-
stone (possibly the same as above) also is reported
along Llagas Creek in the Morgan Hill quadrangle
(Bailey, Irwin, and Jones, 1964, photo 33). Neither of
these deposits was examined by this writer.
SANTA CRUZ DISTRICT (B-5)
The Santa Cruz district covers those deposits in the
Ben Lomond Mountain-Santa Cruz area of Santa Cruz
County. Limestone has been produced continuously
in this district since 1851, when Davis and Jordan first
established a quarry and lime kiln near Santa Cruz.
Although accurate records are not available, total
limestone production is estimated to be close to 30
million tons. The San Vicente deposit of Pacific Ce-
ment and Aggregates, Inc., yielded about 25 million
tons of limestone, most of which went into the manu-
facture of cement. It is estimated that 3 or 4 million
tons of lime rock were calcined from 1851 to 1947.
Crushed limestone for livestock feed, agricultural use,
riprap, and other purposes also was produced in sub-
stantial amounts.
With one possible minor exception (see Wagner's
Park deposit), all of the limestone is recrystallized and
occurs as massive beds associated with schist and other
metamorphic rocks which are commonly correlated
with the pre-Cretaceous metamorphic Sur Series of
the Santa Lucia Range in Monterey County. Granitic
1978
I MOM l\ I III COASI R s
43
rocks of probable Cretaceous age commonly intrude
the metamorphic rocks. The principal limestone
deposits are found northwest of Santa Cruz, west of
Felton, and northeast of Davenport. Substantial lime-
stone reserves appear to exist in each of these areas.
Silica is the principal impurity at most deposits al-
though magnesia causes problems locally. Schist in-
terbeds and granitic dikes are common enough to
cause a significant waste factor at most deposits.
Nonetheless, most of the deposits appear to be suffi-
ciently large and pure to warrant further exploration
as potential sources of limestone.
In 1964, the only active limestone deposits were the
San Vicente (Pacific Cement and Aggregates, Inc.),
Pacific Limestone Products Company, and Holmes
deposits. These and other known deposits are de-
scribed alphabeticallv below.
Bonnie Doon deposit. Location: SWJ4 sec. 25,
SE'X sec. 26, and NW'/4 sec. 36, T. 10 S., R. 3 W., M.D.,
3 miles east-northeast of Davenport; Ben Lomond 15-
minute quadrangle. Ownership: Mainly Pacific Ce-
ment and Aggregates Division, Lone Star Cement
Corporation, 400 Alabama Street, San Francisco
(1963).
The deposit has been quarried to a minor extent in
NE'/SE1/ sec. 26 by Hinds and Packard, who calcined
lime between 1890 and 1900. Remnants of their stone
kiln and small quarry site can still be seen just east of
Bonnie Doon road. This property was later acquired
by Cowell Lime and Cement Company, which never
worked the deposit. The S.H. Cowell Foundation now
holds the property. The main limestone outcrops to
the southeast, in sees. 25 and 36, are on land belonging
to Pacific Cement and Aggregates. Other than exten-
sive diamond drilling in SW'/, sec. 25 done by the
present owner during 1959 and 1960, this portion of
the deposit is undeveloped.* Also, two prospect tun-
nels are shown on the Davenport 7'/,-minute quadran-
gle (1959 ed.) in SW % sec. 25.
The Bonnie Doon deposit consists of one or more
bodies of crystalline limestone and is intermittently
exposed over a northwest-trending area 3,500 feet long
and as much as 1,500 feet wide. Miocene sedimentarv
rocks overlap the deposit on most sides, concealing the
true extent of the deposit. The approximate distribu-
• Development of this deposit was completed in mid-l°70 to supply limestone
— formerly supplied by the San Vicente Creek deposit — to the PCA ce-
ment plant at Davenport The company reports (Herb Gaskin, 1°7I,
personal communication) that the new quarry is located in SW'/.SW'/,
sec. 25, T. 10 S., R. 3 W., nearly 3 miles east-northeast of the plant The
floor of the quarry is at an elevation of 800 feet. The multi-benched face
is worked downward in a manner similar to that at the San Vicente Creek
quarry. A maximum overburden of 100 feel is anticipated as the quarry
is developed northeastward After quarrying, the crystalline limestone is
crushed in a semiportable plant ( 1,140-tons-per-hourcapacity) and stored
in a large concrete silo prior to a 3-milc belt-conveyor trip to the cement
plant Shale from a new quarry in the Monterey Formation (5) provides
much of the alumina and silica needed to make cement. This quarry is
situated along the conveyor route, halfway between the cement plant and
limestone quarry, in sec. 34. The new crushing-storagc-transfcr facilities
cost $7 million to install. Capacity of the conveyor is 1,000 tons of lime-
stone or 630 tons of shale per hour
tion of limestone is shown by Branner et al. (1909,
maps) and Clark (1970). The limestone is w hite to
gray and generally coarse crystalline, but some is fine
crystalline and may be dolomitic or siliceous. Analy-
ses of two samples from the Bonnie Doon quarry show
94% and 95.87% CaCOj and 2.8% and 2.93% MgC03
respectively (Eckel, 1933, p. 353). Some schist in-
terbeds and granitic dikes occur locally with the lime-
stone. Limestone reserves are difficult to assess
because soil and vegetative cover mask the continuity
between outcrops. The deposit is well disposed for
open-quarry development, the outcrops occurring
over 600 feet of relief. Proximity of Bonnie Doon and
Smith (Irade roads render good accessibility.
Pacific Cement and Aggregates recently drilled
about 30 exploratory holes in SW'/4 sec. 25, mainly
above an elevation of 1,000 feet. Although some minor
schist beds were encountered, approximately 7'': mil-
lion tons of limestone reserves reportedly were devel-
oped. The company contemplates utilizing this
deposit as a future source of limestone for its Daven-
port cement plant, which is 6 to 7 miles away by road.
Cowell Home Ranch deposits. Location: Sees. 2,
3, 9, 10, 11, 14 (proj.), T. 11 S., R. 2 W., M.D., 1'/, to
3 miles west and northwest of Santa Cruz City Hall;
Santa Cruz and Felton 7'/,-minute quadrangles. Own-
ership: University of California at Santa Cruz and
S.H. Cowell Foundation, 25 California Street, San
Francisco (1963).
The Cowell Home Ranch deposits were first devel-
oped by I. E. Davis and A. P. Jordan who established
a lime plant and quarry in 1851 (Logan, 1947, p. 318-
319). The kiln was located near NW cor. sec. 14, just
west of the present ranch house. Limestone immedi-
ately to the south and within half a mile to the north
of the kiln area was the early source of lime rock.
Later, Davis joined with Henry Cowell and continued
operating the deposits through the 1880s. During this
period, additional quarries and kilns were established
1 '/2 miles to the west in sec. 9 at the Wilder Creek-Cave
Gulch deposit. About 1895 Cowell acquired sole own-
ership of the limestone property and formed the
Henry Cowell Lime and Cement Companv. Bv the
early 1900s, Cowell controlled nearly all of the lime-
stone reserves in the vicinity of Santa Cruz, and some
of the deposits near Felton and Bonnie Doon (see [XL
and Bonnie Doon deposits) . The earlv quarries on the
Home Ranch eventually were closed down, and most
of the limestone produced af'er about 1910 came from
the quarry in SE1/, sec. 3. Continuous kilns were erect-
ed at Rincon Station to burn this limestone; but only
the dense finer crystalline limestone could be effec-
tively processed, the coarse crystalline white lime-
stone being burned in pot kilns near the ranch house
(Huguenin and Costello, 1920, p. 237). About 1920,
pot kilns were erected at Rincon Station and, thereaf-
ter, all the limestone was burned at the new facilities.
Other quarries in sees. 2 and 11 were operated less
4—89454
44
California Division of Mines and Geology
Bull. 197
extensively, but it is not known when they were devel-
oped The Cowell Lime and Cement Company ceased
operating about 1947. Prior to that, the Cowell Home
Ranch deposits had been utilized as a source of lime
rock continuously for 96 years, with the possible ex-
ception of a few years prior to 1900. The only produc-
tion in recent years was in 1956 and 1957 when
Granite Rock Company produced a large amount
(200,000 tons reportedly) of limestone for riprap from
the quarry located in W1/, cor. sec. 11.
The Home Ranch deposits consist of numerous
small to moderately large bodies of crystalline lime-
stone associated with schist and other metamorphic
rocks similar to the Sur Series of the northern Santa
Lucia Range. Locally, the metamorphic rocks are cut
by granitic rocks of Cretaceous age. Although bedding
features are generally obscure, wide variations in bed-
ding attitudes as well as common breccia features indi-
cate the limestone masses to be considerably disrupted
by faulting. Young sedimentary strata and heavy soil
cover the limestone in many areas, making it difficult
to ascertain the extent of the various deposits; some of
the limestone bodies may be larger than indicated on
the accompanying map (figure 4). The limestone
ranges from fine to very coarse crystalline and from
nearly white to gray and blue gray, sometimes being
banded or mottled. In many places, schist or quartzitic
rocks are interlayered with the limestone; and, locally,
granitic dikes and quartz veins cut the limestone.
Aside from the noncarbonate rocks associated with
the deposits, the main impurities in the limestone ap-
pear to be silica and silicate minerals. Dolomite rock
was not identified in these deposits but may be present
locally. Results of chemical analyses are presented in
table 9. Other analyses are given in Eckel (1933, p.
353).
The several deposits and quarries that lie on the
Cowell Home Ranch were examined briefly by this
writer in July and August 1963. They are described
below by letter designation (A, B, C, D, E, F), the
letters corresponding to those shown on the map (fig-
ure 4).
Figure 4. Map of limestone deposits near Sonto Cruz.
1978
1 [Ml sm\l IN I III COASI K \\(.l s
Photo 8. Looking northeast at Pociftc Cement and
Aggregates' San Vicente Creek deposit, operated
until 1970. Ancient crystalline limestone is overlain
by Miocene sandstone and shale (upper bench).
Limestone blasted from quarry benches was
moved to glory holes at quarry floor and trans-
ferred underground to a rail system for 3-mile haul
to cement plant for further crushing and process-
ing. Photo courtesy of Pacific Cement and Aggre
gates Div., Lone Star Cement Corp.
Photo 9. Pacific Cement and Aggregates' cement plant west of Santa Cruz. Limestone and shale from nearby deposits are used to manufacture cement by
the dry process. Pier (lower right) was used formerly to ship cement by ocean vessel; cement is now hauled by truck. Photo courtesy of Pacific Cement and
Aggregates Div., Lone Star Cement Corp.
46
California Division of Mines and Geology
Bull 197
Deposit A. A sinuous line of outcrops is exposed
more or less continuously along an unnamed creek for
6,000 feet between NW'/4NW'/4 sec. 14 and NW cor.
sec. 1 1. Although 5 to 10 feet of soil overburden masks
the limestone on both sides of the creek, the westerly
strike of the bedding in places indicates the deposit
locally might extend farther east and west than is
shown on the map. The character of the limestone is
quite variable in texture and color, and some is sili-
ceous. At the south end, two small quarries are devel-
oped in limestone that is predominantly blue gray and
medium crystalline. A few hundred feet to the north,
near the old stone kiln remnants, fine- and coarse-
crystalline, off-white to light-gray types of limestone
are found. Obscure planar structures suggest a N 75°
W strike with a vertical to steep south dip. Farther
north in SW'/SW1/ sec. 11, bold outcrops of fine- to
extremely coarse-crystalline, white- to blue-gray,
high-calcium to highly siliceous limestone exist. At a
tiny quarry near the south end of the outcrops, a 2-
foot-thick interbed of schist indicates that at least part
of the deposit is flat-lying. The area was explored by
diamond drilling in 1955 by Marquette Cement Com-
pany.
The most extensively developed part of Deposit A
lies near W1/, cor. sec. 1 1. Here, the predominant types
of limestone are: 1) off white, coarse crystalline with
occasional gray bands, and 2) gray, fine to medium
crystalline. Results of chemical analyses of each of
these rock types are given in table 9. Sample CH-2
indicates the white limestone to be of high quality, but
sample CH-1 shows about 3 percent each silica and
magnesia to be present in the gray rock. The main
quarry is nearly 1,000 feet long, 50 to 300 feet wide,
and has a maximum face of 60 or 70 feet. An estimated
300,000 tons of limestone has been quarried here; two-
thirds of this reportedly was used for riprap along the
San Lorenzo River about 1956-57. Other small quar-
ries may have been developed elsewhere in the deposit
but were not recognized.
Deposit B. Located mainly in SE'/4 sec. 3, this
deposit has provided the main source of lime-rock for
Cowell since about 1910. The deposit is about 900 feet
long, at least 300 feet in maximum width, and is ex-
posed through a total relief of about 100 feet. A little
schist is exposed on the south wall, and thin streaks of
biotite-garnet schist have been penetrated by drill
holes. The deposit appears to dip gently to steeply
south and may be broken to some extent by faults. As
much as 10 feet of soil overburden plus vegetation and
quarry debris tend to conceal the areal extent of the
deposit. Diamond drilling conducted by Marquette
Cement Company in 1955 reportedly penetrated lime-
stone, with only thin streaks of foreign matter, to a
depth of 200 feet. Most of the limestone is off white to
light gray with some dark gray banding, coarse crys-
talline, and locally graphitic. The high calcium con-
tent of the limestone is reflected in the analyses of 5
samples — CH-3 and 4; SACR-1 to 3— given in table 9.
It is interesting to note the consistent differences in
contents of MgO, SiO;, A120,, and P2Os reported for
the two groups (SACR, CH) of samples. The differ-
ences probably reflect the analytical methods em-
ployed by the analysts more than the chemistry of the
samples.
Deposit B is developed by an irregularly benched
pit-quarry with maximum dimensions of about 800
feet by 300 feet by 100 feet. It is estimated that 500,000
to 1 million tons of limestone were produced from this
deposit prior to 1947. Most of this was hauled to kilns
at Rincon for calcining. Since 1947, only minor
amounts of rubble and architectural stone have been
taken. Additional quarrying apparently was con-
ducted immediately to the southeast, but quarry de-
bris masks any limestone that may have cropped out
in that area.
Deposit C. This deposit consists of limestone ex-
posed intermittently over an elliptical area 1,700 feet
by 1,100 feet in NW1/, sec. 11. Much of the limestone
is coarse to very coarse crystalline, white to light gray,
and high calcium. It is interbedded with schist to some
extent and is overlain to the east by gently dipping
beds of Miocene sandstone. Crude bedding in some
places indicates that stratification dips 55 to 65° N; but
some variations in dip, as well as brecciation features,
suggest that the deposit is structurally complicated.
Although the relative proportions of limestone and
schist are not known, the deposit is exposed through
300 feet of relief and contains at least several million
tons of limestone. The deposit is developed by an old
hillside quarry approximately 120 feet by 60 feet with
a maximum face of 50 feet. It is accessible by a dirt
road from the north.
Deposit D. Located in the SW/4 sec. 2, this deposit
appears to have a westerly elongation of more than 500
feet and a maximum width along the road of 300 feet.
It consists of coarse-crystalline, off-white to gray,
banded limestone with some very coarse-crystalline
white limestone. Biotite schist borders the deposit on
the north; the other boundaries are masked by soil and
heavy vegetation. Near the quarry, the apparent strat-
ification dips steeply south. The deposit was worked
many years ago by means of an open quarry about 100
feet in diameter with a maximum face of 30 feet.
Deposit E. Situated in SW1/, sec. 2, a few hundred
feet north of deposit D. It was tentatively mapped by
G. W. Leo (1967 and unpublished Stanford thesis) as
an elliptical mass 1,400 feet long by 700 feet wide.
Limestone outcrops and float a few hundred feet to
the east may be an extension of the deposit. Much of
the limestone at the quarry is fine to medium crystal-
line and light to medium gray; however, some is coarse
crystalline and white to gray. The attitude of the
deposit is not known, and the mass appears to be bro-
ken by faulting. Details of the deposit are concealed by
1978
1.1M1S10NI IN III! COASI RAN(JKS
47
dense vegetation and soil overburden. The deposit
was worked through an open-faced quarry 300 feet by
150 feet w ith a maximum face of 70 feet. Heavy over-
growth indicates the quarry has not been worked tor
at least 30 to 40 years. Production is estimated to have
been on the order of 100,000 tons. The remains of old
stone kilns can be seen along the dirt road just south
of the deposit.
Deposit F. Includes the extensive limestone expo-
sures along the Wilder Creek-Cave Gulch drainage in
SW'/4 sec. 3, E'/j sec. 9, and W1/, sec. 10. As mapped by
(i W. Leo (1967 and unpublished Stanford thesis),
the limestone crops out over an irregular, sinuous area
a mile long and 600 feet to 1,500 feet wide. The lime-
si one is poorly exposed but appears to be interbedded
with schist and quartzite to some extent and cut local-
[y bv granitic dikes. Variable bedding attitudes sug-
gest that the limestone exists as several discontinuous
sequences or masses. The best quality limestone ap-
pears to be centered along Cave Gulch at the
northeastern end of the deposit. Much of this lime-
stone is high calcium, coarse crystalline, and off w hite
to light gray with faint gray streaks or bands. Only a
few small dikes of granitic rock penetrate the lime-
stone in that area. Chemical analyses of samples (CG-1
and 2, table 9) show the variations in the better quality
limestone found in the Cave Gulch area along Empire
Grade. In the western part of the deposit (near the
quarries in sec. 9), the limestone is more variable,
being off white to gray, fine to very coarse crystalline,
and locally siliceous. Some schist interbeds were not-
ed, and granitic dikes and quartz, veins exist locally.
Table 9. Chemical analyses of typical limestone samples
from the Cowell Home Ranch, Holmes, and IXL deposits, Santa
Cruz district.
Sample
SOt
Fefij
00
MgO
K20
Ign
loss
CH-1
S.00%
0.34*
0.13%
48.50%
3.20%
0.07%
0.10%
43.3*
CH-2
1.10
0.00
0.09
54.10
0.77
0.00
0.01
43.1
CH-3
1.70
0.00
0.07
53.40
0.50
0.00
0.11
43.5
CH-4
1.60
0.00
0.07
54.10
0.42
0.00
0.09
434
CG-1
2.60
0.60
0.19
52.30
0.88
ND
0.03
43.3
CG-2
0.80
0.25
0.09
54.20
0.14
ND
0.05
43.4
SACR-I
0.22
0.11
0.04
54.56
0.93
ND
tr
ND
SACR-2
0.20
0.12
0.06
53.80
1.52
ND
tr
ND
SACR-!
0.20
0.11
0.05
53.44
1.79
ND
tr
ND
SACR-4
1.31
0.45
0.07
53.38
0.93
ND
tr
ND
SACR-5
0.20
0.10
0.04
54.58
0.88
ND
tr
ND
SACR-6
0.29
0.17
0.06
54.50
0.93
ND
ir
ND
SACR--
0.23
0.14
0.05
54.51
0.93
ND
tr
ND
\D = not done
CH and CG samples collected by Earl W Hart and analyzed by Matti Tavcla
and Lvdia Lofgren of California Division of Mines and Geology, 1963.
SACR-I to 7 collected by Oliver E Bov.cn of California Division of Mines
and Geology and analyzed by Abbot A. Hanks, Inc., 1955.
CH-1 and 2 from quarry near W'/, cor. 1I-1IS-2W, Cowell Home Ranch
deposit A.
CH) and 4 and SACR-I to ) from quarry in SE'/. 3-11S-2VV, Cowell Home
Ranch deposit B
CG-1 and 2 from Cowell Home Ranch deposit F where crossed by Empire
Grade— NW'/, I0-IIS-2W and SW1/. M1S-2W, respectively
SACR-4 is float from quarrv at Holmes deposit, NE1,. 20-IOS-2VV
SACR-5 to 7 from quarry It IXL deposit. SE1/. I7-10S-2W
The Wilder Creek-Cave Gulch deposit has been de-
veloped only in sec. 9, where I lenry Cowell Lime and
Cement Company produced limestone for lime from
about 1880 until the turn of the century. Limestone
was worked in three quarries, the largest and most
easterly being 300 feet in diameter and having a max-
imum face of nearly 100 feet. Two smaller quarries are
situated to the west. Several hundred thousand tons of
limestone were produced and burned at the nearby
kilns, remnants of which still stand. The kilns were
oil-fired and when it became uneconomic to haul oil
to the kilns the operation was shut down.
Reserves. Limestone reserves of the Cowell Home
Ranch deposits are difficult to estimate accurately be-
cause of poor exposures (soil cover, dense vegetation).
However, based on an areal extent of about 250 acres
of limestone outcrop (figure 4), combined limestone
reserves may be estimated at 850,000 tons per foot of
depth. This figure is too large in that it disregards
limestone quality and includes noncarbonate rocks as-
sociated with the limestone. On the other hand, some
of the limestone deposits may extend under soil over-
burden beyond the deposit limits mapped. It is clear
that further exploration is necessary to assess the re-
serves of the various deposits. From an economic
viewpoint, some of the advantages of the Cowell
Home Ranch deposits are: 1) large reserves, 2) good
accessibility, and 3) proximity to markets and major
transportation lines. The main disadvantage is that
much of the limestone lies on the campus of the L'ni-
versity of California at Santa Cruz, construction of
which began about 1964, and may not be available for
future development. Beyond the campus boundary
(figure 4), only the Wilder Creek-Cave Gulch deposit
(F) appears to be of sufficient size to support large-
scale development, but very little is known about spe-
cific reserves and limestone quality of that deposit.
Deposits C, D, and E also lie partly outside the campus
site and may be of future interest.
Other references- Browne, 1868, p. 244; Irelan, 1888, p. 554, Crawford,
1896, p. 631; Aubury, 1906, p. 83; Loizure, 1926, p. 84; Hubbard, 1943, p.
43; Leo, 1967, p. 31, 41.
Holmes deposits. Location: NE% sec. 20, T. 10 S.,
R 2 W., M.D., l1/, miles west of Felton; Ben Lomond
15-minute quadrangle. Ownership: Citizens Utilities
Company of California, Boulder Creek, leased by
Limestone Products, Incorporated (1963).
W. T. Holmes Lime Company produced large
amounts of limestone for lime from these deposits for
more than 52 years prior to 1936, when their opera-
tions ceased (Logan, 1947, p. 319). Production during
the early years amounted to 50,000 to 100,000 barrels
of lime per year (equal to about 10,000 to 20,000 tons
of limestone per year) but was less later on. The lime-
stone was burned in a series of pot and continuous
kilns located between the deposits and Felton. Since
early 1955, tailings at the main quarry have been
4S
California Division of Mines and Geology
Bull. 197
worked intermittently, and small amounts of lime-
stone have been produced for use as road material and
as roofing granules. Most or all of the later production
was by Western Limestone Company (operated and
owned in 1963 by Harry Crowley, Felton) apparently
under a sublease arrangement with Limestone
Products, Incorporated (a subsidiary of Granite Rock
Company, Watsonville) . The latest production was in
late 1962 or early 1963, but the operator was preparing
to produce additional limestone from existing tailings
piles in August 1963 when the property was visited.
The Holmes deposits consist of massive beds of
crystalline limestone and common schist interbeds ex-
posed in several ill-defined areas in NE'/4 sec. 20. The
largest deposit, lying astride Bennett Creek, covers an
area perhaps 1,500 feet long east- west by 700 feet wide.
Although much of the deposit is covered by quarry
debris and vegetation, the limestone apparently oc-
curs in crudely bedded sequences which are as much
as 50 or 100 feet thick and which are interspersed at
irregular intervals with thinner sequences of mica
schist. Based on obscure stratification, the predomi-
nant dip appears to be about 50° N. The limestone is
nearly white to gray, fine to coarse crystalline, and
high in calcium. An analysis (SACR-4) of typical
coarse-crystalline rock from the quarry is given in
table 9. A few hundred feet south of the main area,
near the crest of the ridge, a small deposit of similar
limestone appears to dip about 60° S. To the east of this
deposit are large tailings dumps consisting largely of
off-white to gray, medium- to coarse-crystalline lime-
stone. Other small limestone deposits are reported to
the south and west(?) in NE'/4 sec. 20 but were not
examined.
Development of the main Holmes deposits has been
by surface and underground methods. The main quar-
ry, consisting of several benches over a relief of about
400 feet, covers an area of 8 or 9 acres. At an elevation
of about 1,2 50 feet just north of Bennett Creek, an adit
leads to a series of underground rooms, supported by
pillars and extending more than 400 feet to the west.
Although the adit is partly caved at its portal, the
workings are reported to be accessible and in good
condition. At the southwest part of the deposit, a quar-
ry with a floor elevation of 1,400 feet opens into the
main quarry area. This quarry is about 150 feet wide,
400 feet deep, and has a maximum face of nearly 200
feet. Three hundred feet to the southeast, a smaller
limestone deposit is developed by a quarry having a
diameter of about 100 feet and a face of more than 100
feet. An old tramway site and a large tailings dump of
medium- to coarse-crystalline limestone lie to the east
of the quarry. Another old quarry is reported to the
southeast near a southwest branch of Bull Creek.
Remnants of two kiln sites can still be observed in sec.
21 immediately east of the deposits.
The present operator, Harry Crowley, has not done
any quarrying but has utilized the extensive dumps at
the main quarry as a source of limestone. A mill, locat-
ed below the lowest two benches, consists of jaw and
gyratory crushers, screens, and two large metal stor-
age bins. A portable crusher and grizzly also were
previously used to produce crushed limestone. In Au-
gust 1963, the operation was inactive except for repair
work on the mill.
Based on the size of workings, total limestone pro-
duced at the various Holmes deposits may have aggre-
gated more than a million tons. Recent production of
limestone from tailings probably amounted to a few
thousand tons per year. Limestone reserves are virtu-
ally impossible to estimate, as quarry debris, soil, and
vegetation conceal much of the limestone and related
schist. However, reserves at the main deposit could
amount to several million tons or more. The deposits
to the south appear much smaller, although reserves
are undetermined. Extensive surface and subsurface
exploration, including drilling, are needed to evaluate
the deposits.
Other references: Irelan, 1888, p. 554; Crawford, 1894, p. 395; Aubury,
1906, p. 85; Huguenin and Costello, 1920, p. 238; Laizure, 1926, p. 85;
Hubbard, 1943, p. 44; Leo, 1967, p. 31.
Ice Cream Grade deposits. Location: SE1/, sec. 1 3,
T. 10 S., R. 3 W. and W'/4 sec. 18, T. 10 S., R. 2 W.,
M.D., 3'/2 miles west of Felton; Ben Lomond 15-
minute quadrangle. Ownership: Not determined
(1963).
Several small limestone deposits are exposed along
Ice Cream Grade road in the vicinity of Laguna Creek.
The limestone is crystalline and forms well-defined
massive beds interlayered with schist and quartzite.
These small deposits are somewhat impure and appear
to be of little or no economic interest.
Two old stone lime kilns, situated on the east bank
of Laguna Creek just south of the Ice Cream Grade
road, testify to early efforts to develop limestone in the
vicinity. The kilns are identical; each measures 15 feet
by 21 feet on the inside, and both are completely open
at the top (no stack). No limestone quarry was identi-
fied in the area, and there is evidence that only a little
lime was burned. A quarry location and the general
distribution of limestone outcrops is indicated by
Branner et al. (1909, map) and Leo (1967, p. 30).
IXL deposit. Location: SE1/, sec. 17, T. 10 S., R. 2
W., M.D., l!/2 miles west-northwest of Felton; Ben
Lomond 1 5-minute quadrangle. Ownership: H. S. Co-
well Foundation, 25 California Street, San Francisco
(1963).*
A substantial amount of limestone for lime was pro-
duced from this deposit between the 1880s and 1919.
The IXL Lime Company opened the deposit about
1885 or earlier and produced 50,000 barrels of lime per
year (Irelan, 1888, p. 555; Crawford, 1894, p. 395).
Around 1895, the deposit was being operated by
Blackman and Cerf who manufactured small quanti-
• The deposit rcportcdlv was purchased by Ciranitc Rock Company in 1970
as a source of riprap.
1978
I.IMl SIOM IN I IIK COASI R \\(,l S
49
ties of lime (Crawford, 1896, p. 631). The Henry Co-
well Lime and Cement Company acquired the
property about 1905 and produced a large amount of
lime rock until 1919, when they ceased operations.
There has been no development since that time.
The deposit is situated at the east end of a high,
east-plunging spur flanked by South Fall Creek and a
northwest tributary. The limestone has been mapped
as an irregular lensoid mass (in plan), having a length
of nearly 2,000 feet and a maximum width of 900 feet,
and is exposed over 700 feet of relief (Leo, 1967, and
unpublished Stanford thesis). It consists of thick beds
of high-calcium limestone interbedded in some places
with biotite schist. Where bedding can be observed,
the strike is usually west or northwest; but the dips are
variable to the north and south, indicating structural
complications. At one place on the north side of the
deposit some granitic rock is exposed, but its relation-
ship to the limestone is not known. Most of the lime-
stone near the east end of the deposit is white to light
gray, coarse to extremely coarse crystalline, generally
graphitic, and high in calcium. However, some is fine
to medium crystalline, white to dark gray, and mot-
tled or banded. Chemical analyses of three samples
(SACR-5 to 7) given in table 9 show the type coarse-
crystalline limestone to be of good quality.
The deposit was worked at the east and north sides
through several quarries. One quarry, situated about
250 feet higher than the kilns on the north side of the
deposit, has a high face and is 40 feet by 40 feet in floor
plan. A double-track tramway served the quarry and
kilns. Lower in elevation and to the southeast is an-
other quarry with a face of perhaps 200 feet. Remnants
of a bank of three stone kilns and several enormous
piles of broken limestone exist below the quarries.
Proved limestone reserves cannot be determined
without drilling, particularly as the ratio and relation-
ship of noncarbonate rocks to limestone is not known
in detail. However, available limestone reserves may
amount to several million tons or more. If the chemi-
cal analyses are representative of a substantial volume
of rock, the deposit might be a useful source of lime-
stone for the manufacture of glass and lime, and for
other industrial uses.
Other references: Aubury, 1906, p. 86; Huguenin ond Costello, 1920, p.
238; Loizure, 1926, p. 85; Hubbard, 1943, p. 44, Logan, 1947, p. 319; Leo,
1967, p. 31.
Pacific Limestone Products Company (Kalkar; De
Dero; Thurber; Caplatzi; Miller) deposits. Loca-
tion: SE'/4SW'/4 sec. 1 1 and adjacent part of sec. 14, T.
11 S., R. 2 W., M.D., just west of Spring Street in
northwest Santa Cruz (city); Santa Cruz 7'/2-minute
quadrangle. Ownership: Pacific Limestone Products
Company (estate of Fred W. Johnson), 535 Spring
Street, Santa Cruz (1967).
The deposits consist of crystalline limestone uncov-
ered in two adjacent quarries. The north quarry was
worked by Louis De Dero (pre-1894 to 1907) and
W.A. Caplat/.i (1907 to 1922), who produced crushed
rock, poultry feed, and agricultural limestone. The
south quarry was developed as a source of crushed
rock at least as early as 1894 by T.J. (or S.L.) Thurber
and later (pre-1920), on a smaller scale, by W.E. Mil-
ler (Crawford, 1894, p. 395; 1896, p. 631, 632; Aubury,
1906, p. 88, 324; Huguenin and Costello, 1920, p. 237,
239; Laizure, 1926, p. 86-88). Pacific Limestone
Products Company began operations in 1922 when
they took over the north (Caplatzi) quarry, and ex-
panded in 1927 when they acquired the south (Miller)
quarry (Hubbard, 1943, p. 44-46). Livestock feed and
poultry grits, marketed as the "Kalkar" brand, have
been the principal products of the present operation.
The two quarries are situated 450 feet apart on a
gentle soil-covered slope. The area of limestone uncov-
ered is about 8 acres at the north quarry and 3 to 4
acres at the south quarry (figure 4). Extent of the
deposits beyond the quarries is masked by soil at least
6 to 8 feet thick. The deposits mainly consist of mas-
sive beds of coarse- to exceedingly coarse-crystalline,
off-white to blue-gray, relatively pure limestone in-
terbedded with thin beds, bands and lenses of impure
limestone and calc-silicate rocks. The south deposit is
also cut by a granitic dike. The impure interbeds,
which are white to dark gray and generally fine
grained, are more prevalent at the north deposit. Con-
tact metamorphism and introduction of mineralizing
fluids have given rise to the formation of a wide vari-
ety of silicates, sulfides, and arsenides, including some
rare minerals (Gross et al., 1967; Leo, 1967, p. 41). As
a result, the locality has become noted as an important
site for mineral-collecting. Both deposits are some-
what crushed and broken by minor faults. Bedding
attitudes are obscure but appear to be gentle and to the
north in the north quarry. Limestone reserves are un-
known because the vertical and lateral extent of the
deposits have not been determined. Chemical analyses
of five samples (Kal-1 to 5) reflect the variable quality
of limestone at the deposits (see table 10).
The two quarries have been worked on a modest
scale for 70 years (prior to examination in 1963). The
north quarry is the largest, having an irregular plan
and maximum dimensions of 1,000 feet by 600 feet by
80 feet. Maximum dimensions of the south quarry are
estimated to be 500 feet by 250 feet by 80 feet. Roughly
1 million tons of limestone and associated rocks have
been quarried from the deposits. Both quarries are
worked by primary and secondary blasting and hand-
sorting. The impure limestone and calc-silicate rocks
are stored in unused parts of the quarries for eventual
sale as rubble and riprap. The purer coarse-crystalline
limestone is hand-loaded into small skips, which are
periodically picked up by special vehicles and deliv-
ered to the adjacent mill for processing. At the mill,
which has a capacity of 100 tons per 8-hour day, the
limestone is reduced in size through jaw and gyratory
crushers, a hammer mill, and an impactor. The
material is screened to several grit sizes and some is
ground to flour. Poultry feed and grit are the most
50 California Division of Mines and Geology Bull 197
Table 10. Chemical analyses of selected limestone samples, Pacific Limestone Products Company deposits, Santa Cruz County.
Ignition
Description Sample SiOs Al£)3 Fe^Oj CaO MgO PsO, loss Total
South quarry (N'/i cor. sec. 14-11S-2W)
Coarse-crystalline, blue-gray limestone with small lensoid
patches of fine-grained material.
White, coarse-crystalline limestone with 50% bands of fine-
grained, quartzose limestone.
North quarry (SW'/i sec. 11-11S-2W)
Extremely coarse-crystalline, dove-gray to blue-grav lime-
stone
Same as Kal-3, but nearly white and with lenses of medium-
grained quartz "sand"
Fine- to coarse-crystalline, light-to dark-gray, impure lime-
stone.
Kal-I
2.90%
0.23%
0.12%
49.4%
1.00%
1.00%
41.0%
95.65^
Kal-2
14.50
2.30
0.20
44.9
0.40
0.01
37.9
100.21
Kal-3
1.70
0.20
0.06
53.8
0.70
0.01
42.8
99.27
Kal-4
19.50
1.20
0.50
41.5
0.50
0.01
36.7
99.91
Kal-5
6.10
1.60
0.30
38.7
12.90
0.34
39.5
99.44
Samples collected by E. W. Hart and analyzed by Matti Tavela, Division of Mines and Geology, 196!
important products, the various sizes being referred to
as "flour, bird, fine, pidgeon, medium, coarse and tur-
key" The processed limestone is guaranteed by the
operator to contain a minimum of 90% calcium car-
bonate. Additives — including phosphate, iron oxide,
salt, copper, cobalt, zinc and sulfate — are blended
with some of the products. The material is sold in bulk
and in bags. In addition to the above products, rubble,
riprap, and some agricultural limestone are sold. Ship-
ments are made by truck or rail, principally to central
California markets.
Other references. Fitch, 1931, p. 8; Logon, 1947, p. 320; Leo, 1967, p. 31,
41.
Peasley Gulch deposit. Location. SW1/ sec. 9, T.
1 1 S., R. 2 W., M.D. (proj.), 3 miles west-northwest of
Santa Cruz business district; Santa Cruz 7'/2-minute
quadrangle. Ownership: Not determined.
A small body of crystalline limestone associated
with schist and granodiorite is exposed in Peasley
Gulch l!/4 miles north of State Highway 1. The lime-
stone exposures, which extend several hundred feet
west of the gulch, cover a lenticular area about 400 feet
long by 50 feet wide (Oliver E. Bowen, oral communi-
cation, 1965). Most of the limestone is off-white,
coarse crystalline and high in calcium, although a thin
zone of gray, medium-crystalline dolomite is present
near the south contact. Typical limestone and dolo-
mite samples, collected by Oliver E. Bowen, were
analyzed by Lydia Lofgren of the Division of Mines
and Geology in 1962:
Ign
Div So CM) MgO Si(). I/O, le.O, P.O, loss
44-PE-l 55.25% 00.51% 0,53% 0.09% 0.09% 0.0100% 43.49%
44-PE-2 33.20 19.09 1.24 0.25 0 25 0.0111 45.74
The deposit is not developed and probably is too
small to be of economic interest.
San Vicente Creek deposit (Pacific Cement and
Aggregates; Santa Cruz Lime Company; Santa Cruz
Portland Cement Company). Location: Sec. 22, T.
10 S., R. 3 W., M.D., 2'/2 miles north-northeast of the
PCA cement plant and the adjacent town of Daven-
port; Ben Lomond 1 5-minute quadrangle. Ownership:
Pacific Cement and Aggregates Division, Lone Star
Cement Corporation, 400 Alabama Street, San Fran-
cisco (1968).
The San Vicente Creek deposit was first developed
about 1900 by the Santa Cruz Lime Company, which
operated there for 5 or 6 years. They quarried lime-
stone on the west side of San Vicente Creek and
burned the material in three pot kilns, producing
about 300 barrels of lime per day (Aubury, 1906, p.
87). In 1907, a cement plant was completed by Santa
Cruz Portland Cement Company at Davenport, and
the deposit has served as the source of cement '•ock
ever since. The company merged with Pacific Coast
Aggregate Company in 1956, the new firm emerging
as Pacific Cement and Aggregates, Incorporated
(Bowen and Gray, 1962, pt. 2, p. 4). About 1966, the
company became a division of Lone Star Cement Cor-
poration.
The deposit is situated astride San Vicente Creek
where crystalline limestone is exposed in the quarry-
expanded canyon for a length of 3,000 feet, a max-
imum width of 1,400 feet, and a relief of about 450 feet.
Schist is locally interbedded with the limestone and
constitutes part of the north, west, and south bounda-
ries of the deposit. The limestone and schist are part
of a metamorphic sequence of rocks considered to be
equivalent to the Sur Series of pre-Cretaceous age.
The metamorphic rocks were intruded by Creta-
ceous^) quartz diorite, whose contact with the lime-
stone is exposed along the northwest and southeast
margins of the deposit (Branner et a/., 1909). Diorite
is reported to penetrate the limestone body locally as
1978
Limes ion f in mi Coasi Ramjks
51
sills (Fitch, 1931, p. 3 ). Overlying the crystalline rocks
on both sides of San Vicente ("reek canyon and con-
cealing the southwest and northeast extent of the lime-
stone is a sequence of Miocene sedimentary rocks that
dips gently southwest. A maximum thickness of 350
feet of sedimentary overburden is exposed west of the
canyon and somewhat less is exposed to the northeast.
From bottom to top, the sedimentary strata are com-
posed of the following units, with estimated max-
imum thicknesses indicated: 1) hard calcareous
sandstone of the Yaqueros Formation (?), 20-100 feet;
2) transitional softer concretionary sandstone, 100
feet; and 3) shale or mudstone of the Monterey Forma-
tion (?), 150 feet.
The attitude and subsurface extent of the limestone
bodv is known onlv in places. Based on limited bed-
ding features and the fact that schist was encountered
in underground workings at a shallow depth below
limestone exposed in the west wall of the canyon, the
deposit appears to dip moderately northeast. If so, the
main limestone reserves would lie east of the canyon
beneath the sedimentary overburden. However, the
projected distribution of the deposit at depth may be
complicated by faulting as indicated by the broken
and crushed nature of the limestone and the presence
of minor faults.
Most of the limestone is off white to light blue gray,
medium to very coarse crystalline, high in calcium,
and locally graphitic. Some magnesia is locally present
as silicates and dolomite but is considered a problem
only at the north end of the deposit. Limestone and
associated rocks (weathered schist and calc-silicate
rocks) are commonly broken and crushed, the inter-
mingling making it difficult to maintain good-quality
limestone in some parts of the quarry. Clay and other
noncarbonate fines tend to fill the interfragmental
spaces, thereby further diluting the limestone. Dis-
seminated pyrite is a common minor constituent in
some parts of the deposit. An average analysis of the
quarry-run limestone delivered to the mill is reported
by the companv (R. A. Kinzie, Jr., written communi-
cation, 1963) to be 43.6% CaO, 1.4% Mg(), 14.5%
Si02, 3.6% A120„ 1.5% Fe20„ 0.6% SO,, and 34.0%
ignition loss.
Development of the deposit has been mainly south-
west of San Vicente Creek, although the northeast
wall of the canyon was worked to some extent in the
early years. By 1963, the quarry had been expanded to
an estimated maximum size of 2,700 feet by 1,600 feet.
Quarry operations are carried out in three more or
less distinct phases — stripping, quarrying, and under-
ground transfer. Stripping of the sedimentary over-
burden is done periodically under contract, the last
contract being completed in January 1963. The strip-
ping bench uncovers a 1 50-foot-wide upper surface of
limestone at an average elevation of 870 feet; and the
sequence of sedimentary rock, 130 feet to more than
300 feet thick, is exposed in the bench face. Most of the
overburden is wasted, except for the hard sandstone of
the Yaqueros Formation (?) which is utilized exten-
sively as riprap and breakwater stone. Recent strip-
ping should provide several years of limestone
reserves before further stripping is necessary. Dia-
mond drilling currently being conducted on the oppo-
site side of the canyon is designed to develop limestone
reserves in the northeast part of the deposit.
(Quarrying is conducted along the southwest can-
yon wall where the developed limestone face rises 320
feet above the 550-foot elevation of the quarry floor.
The limestone is worked through several shallow
benches by blasting and bulldozing, the benches pro-
gressing down the face. Some selective quarrving is
necessary to maintain desirable grades of limestone.
Where schist is too prevalent, the material is wasted.
Broken rock collected at the toe of the face is moved
to glory holes on the quarry floor by end-dump trucks,
which are loaded by power shovel, and bv a Michigan
loader.
The limestone is drawn through an underground
transfer system which consists of three glorv holes,
each connected to main haulage ways bv a transfer
raise, bulldozing chamber, and loading chutes. Sec-
ondary blasting is used to reduce oversize blocks in the
bulldozing chambers and "hang-ups" in the transfer
system. The extensive underground transfer system
has been changed little since its installation in 1924,
although fewer glory holes are now employed. The
system is described in detail by Young (1925, p. 249;
1929, p. 954) . Open rail cars are filled at loading chutes
in the haulage ways and transported by battery-pow-
ered locomotives to the mine opening. Electrically
driven locomotives complete the 3-mile haul to the
plant near Davenport.
At the plant, the material is reduced in gyratory
crushers and stored by grade. Two grades of raw lime-
stone are produced, based on the amount of contained
alkalies and other impurities. Raw limestone from the
storage piles is further processed by crushing, grind-
ing, and blending with shale and roasted pyrite ("iron
cinder"). The raw mix is then made into cement by
the dry process, partly by the Lepol system and partly
by conventional rotary kilns. The Lepol system con-
sists of three kilns, each with four parts: 1) a drum-
pelletizer where '/2- to '/,-inch pellets are formed from
the dry mix and added water; 2) a 47-foot traveling
grate where the pellets are partially calcined; 3) a
rotary kiln in which calcining of the pellets is com-
pleted; and 4) a moving-grate cooler. In addition to the
Lepol system, some cement is produced from the dry
mix in six rotary kilns in which conventional clinker
is made.* A seventh kiln is used to calcine shale for the
production of high-silica cement.
Much of the alumina and silica used for cement
manufacture is derived from "shale" or mudstone of
* It is reported by the company (Herb Gaskin, 1°71, personal communica-
tion) that the rotary kilns will be shut down by the end of l°7l because
of stringent air-pollution control standards recently established by the
State. The Lepol kilns currently (June 1971) produce a major portion of
the total cement produced at the plant.
52
California Division of Minfs and Geology
Bull. 197
the extensive Monterey Formation (?). The mudstone
is obtained by the operator from a hillside quarry
located a mile northeast of the plant, near NW'/4 cor.
sec. 34, and is shipped to the plant by rail. The materi-
al quarried is brownish gray, buff weathering, nonfis-
sile, brittle, siliceous, and probably tuffaceous.
Typical analyses of the mudstone, furnished by the
company in 1961, ran as follows: 73-81% SiO;, 7.5-
11.0% A120„ 1.75-2.25% Fe20„ 0.8-1.0% CaO, 0.4-
0.6% MgO, 0.8-1.1% K20, and 0.3-0.6% Na20.
Annual rated capacity of the plant is 3 million bar-
rels of cement. Yearly production is reported by Bow-
en and Gray (1962, plate 2, p. 4) to be roughly 840,000
tons of limestone and associated noncarbonate rock
and 85,000 tons of mudstone (shale) . Total production
of limestone from the San Vicente Creek deposit is
estimated to be about 25 million tons since 1907.
Pacific Cement and Aggregates Division owns an-
other limestone deposit near Bonnie Doon. They re-
cently drilled this deposit to determine its potential as
an additional source of cement raw material (see Bon-
nie Doon deposit). t
Other references: Huguenin and Costello, 1920, p. 233, 239; Laizure,
1926, p. 75-78; Hubbard, 1943, p. 37-39; Logan, 1947, p. 320-321; Leo,
1967, p. 30; Clark, 1970.
Smith Grade deposit. Location: E'/2 sec. 25, T. 10
S., R. 3 W., M.D., 7'/2 miles northwest of Santa Cruz;
Felton 15-minute quadrangle. Ownership: Not deter-
mined (1963).
Crystalline limestone exposures along Smith Grade
Road and Reggiardo Creek have been mapped as a
relatively large deposit by Branner et a/. ( 1909, map) ,
t (Quarrying at the San Vicente Creek deposit ceased in mid-l°70 concurrent
with the opening of the Bonnie Doon deposit 1 miles to the southeast (see
footnote under Bonnie Doon deposit) The San Vicente Creek deposit
will be held as an emergency reserve A major reason for its closing is
believed to have been the cost of removing increasing amounts of over-
burden.
Leo (1967, p. 31; and unpublished Stanford thesis),
and Clark (1970). The limestone commonly is coarse
crystalline and high in calcium, but locally it is im-
pure. Calc-silicate rocks, containing as much as 60%
wollastonite, are exposed along the road, 1,000 feet
west of the E'/ cor. sec. 25; other silicate minerals are
reported elsewhere in the limestone deposit. Quartz-
ite and schist are locally exposed around the borders
of the limestone and probably also exist as interbeds.
Granitic dikes west of the creek further reduce the
purity of the deposit.
As of August 1963, there was no known develop-
ment. The deposit appears to be of only minor eco-
nomic interest because substantial reserves of good
quality limestone are not evident.
Wagner's Park deposit. Location: Probably 1 mile
north of Santa Cruz business district; Santa Cruz T/2-
minute quadrangle. Ownership: Not determined.
"Soft limestone" or "calcareous tufa" from a small
gulch, at a place known as Wagner's Park, and clay
from a nearby bluff were used experimentally by Cali-
fornia Portland Cement Company (not the same as
the firm currently operating in southern California)
to produce portland cement around 1877. The com-
bined materials were processed in a reverberatory fur-
nace and kiln. Some cement was produced, but little
or none was sold. The lack of success is reported to be
due to litigation (Williams, 1883, p. 464) and competi-
tion from imported cement (Crawford, 1894, p. 380).
Chemical analyses (Irelan, 1888, p. 881) show two
samples of limestone to contain 50.31% and 50.02%
CaO, 2.40% and 4.71% Si02, and 1.45% and 1.80%
alkalies. Irelan also presents chemical and physical
data for cement, as well as chemical analyses for the
clay and shale raw materials.
Other references: Williams, 1885, p. 676; Aubury, 1906, p. 184; Bowen
and Gray, 1962, pt. 1, p. 6.
SOUTHERN COAST RANGES REGION (C)
The southern Coast Ranges region includes the
Coast Ranges south of Monterey Bay and the Santa
Vnez Mountains of the Transverse Ranges. The
deposits lie in Fresno, Monterey, San Benito, San Luis
Obispo, Santa Barbara, and Ventura Counties. The
crystalline limestone and dolomite deposits in the
Frazier Mountain area, at the southeast end of the
Coast Ranges, and the various deposits of the Trans-
verse Ranges east of the Santa Ynez Mountains were
not part of this study and are not described herein.
Topographically, the southern Coast Ranges consist
of a series of northwest-trending mountain ranges and
intervening valleys that separate the broad San Joa-
quin Valley from the Pacific Ocean. Included among
the principal mountain chains are all or portions of
the Santa Lucia, Gabilan, Diablo, Temblor, and La
Fan/a Ranges, and the San Rafael Mountains (plate
1C). At its southeast end, the Coast Ranges swing
eastward, merging with the Santa Ynez Mountains
and other east-trending Transverse Ranges.
The region is moderately populated, with most of
the people residing in the Salinas-Monterey, Santa
Barbara-Ventura, and San Luis Obispo-Santa Maria
areas. The economy is based largely on agriculture,
petroleum, and mining. As the region is quite moun-
tainous, many of the carbonate deposits are of limited
accessibility. Principal transportation routes are con-
fined to the larger valleys and the less rugged coastal
areas, and few paved roads cross the mountain ranges.
The Southern Pacific Railroad connects the main cit-
ies with Los Angeles to the southeast (via the coast)
and with San Francisco to the northwest (via Salinas
Valley). There are no major deep-water ports in the
region, although limited facilities are available at sev-
eral ports between Monterey Bay and Ventura.
Historically, many deposits have been developed in
the southern Coast Ranges region. Beginning in the
1880s, perhaps 20 limestone deposits were developed
as sources of lime — mainly for local use although some
limestone was shipped elsewhere in the region. Lime-
stone for cement manufacture has been quarried since
1918 by Ideal Cement Company and its predecessors.
Raw and calcined dolomite has been quarried continu-
ously since 1900 for refractory, chemical, and crushed
rock uses, as well as for the manufacture of magne-
sium metal during World War II. Limestone, dolo-
mite, and mixed carbonate rocks also have been used
extensively for crushed rock, agricultural, and decora-
tive purposes.
Between 1966 and 1968, the active dolomite deposits
were the Natividad (Kaiser Aluminum and Chemical
Corp.) and Westvaco (FMC Corp.) deposits of the
northern Gabilan Range and the Missile City deposit
in the western Santa Ynez Mountains. During that
same period, limestone was quarried for cement
manufacture at the Bryan and Pearce-'I wohy deposit
(Ideal Cement Company) in the Gabilan Range and
for beet-sugar refining at Lime Mountain (Eaton and
Smith) in the southern Santa Lucia Range. Total
limestone and dolomite produced in 1968 amounted to
about 907,000 tons.
The southern Coast Ranges region contains the
largest reserv es of limestone and dolomite of the Coast
Ranges province. The principal deposits consist of
crystalline limestone and dolomite of the metamor-
phosed Sur Series (pre-Cretaceous), fossiliferous and
bioclastic limestone of the Sierra Blanca Limestone
(Eocene) and Yaqueros Formation (lower Miocene),
and impure fine-grained dolomite of the Monterey
Formation (Miocene). Smaller or less pure carbonate
deposits consist of dense limestone with chert, shell
beds, veins, marl, marble onyx travertine, and possibly
caliche that were formed from late Mesozoic(?) to
Quaternary time.
In addition to the recently active deposits, the larg-
est limestone deposits include the Pico Blanco deposit
of the northern Santa Lucia Range and the Sierra
Blanca deposit of the Santa Ynez Range. The lack of
development at both of these deposits has been due to
poor accessibility and, more recently, to the attention
paid to the high recreational or wilderness values in
these areas. An abundance of good quality limestone
appears to be available at these deposits. Smaller
deposits of limestone and dolomite of potential value
exist in the Gabilan Range, northern and southern
Santa Lucia Range, La Panza Range, and Santa Ynez
Range. Carbonate deposits elsewhere in the region
S3
54
California Division of Mines and Geology
Bull 197
appear to be of little economic interest because of size,
impurities, or poor accessibility.
The limestone and dolomite deposits are discussed
alphabetically below by districts (plate lC). The dis-
tricts, which are discussed from north to south, are the
Gabilan Range, Panoche Hills, Northern Santa Lucia
Range, Parkfield-Coalinga, Southern Santa Lucia
Range, and Santa Ynez.
GABILAN RANGE DISTRICT (C-l)
The Gabilan Range district is a 10-mile-wide moun-
tainous area that straddles the Monterey-San Benito
County boundary between the Salinas Valley on the
southwest and the San Andreas fault zone on the
northeast. It extends 45 miles southeastward from
U.S. Highway 101 to Topo Valley where it loses alti-
tude and gives way to the so-called Gabilan Mesa.
Although the Gabilan Range has a maximum eleva-
tion of only 3,454 feet at Mt. Johnson, much of it is
deeply eroded and rugged and accessibility is some-
what limited. Rail facilities are available to the north
at Hollister and San Juan Bautista and to the south-
west at various points in the Salinas Valley. Limited
port facilities exist at Moss Landing on Monterey Bay
(plate 1C).
Pre-Tertiary crystalline rocks comprise the great
bulk of the Gabilan Range. The oldest rocks are schist,
gneiss, marble (limestone and dolomite), and quartz-
ite of the Sur Series of pre-Cretaceous age. During
Cretaceous (?) time, the Sur Series was extensively
invaded by granitic intrusives, and only scattered roof
pendants of the former remain — mainly in the north-
ern half of the range. The granitic rocks range in
composition from granite to quartz diorite but are
mainly quartz monzonite and granodiorite. Overly ing
the crystalline rocks at the northern end of the range
is a highly faulted and folded sequence of sedimentary
and volcanic rocks of Oligocene to middle(?) Miocene
age. Included in this sequence are thick red beds,
breccias, and conglomerates of the Vaqueros Forma-
tion (lower Miocene) derived from the crystalline
rock complex (Allen, 1946). The southeast end of the
Gabilan Range is overlain by rhyolite flows and pyro-
clastics of Miocene age and various marine and non-
marine sedimentary units of Miocene age and
younger.
Limestone and dolomite deposits of economic inter-
est are, with only one exception, restricted to pend-
ants of the Sur Series. The exception is the Vaqueros
Formation which contains thick red beds composed
largely of crystalline limestone rubble derived from
the Sur Series (see Barbee Ranch deposits). The gen-
eral distribution of carbonate rock is fairly well
known, although the extent and quality of many of the
deposits remain to be learned. As can be seen in plate
2, many of the carbonate pendants form linear groups
or belts that trend due west or northwest. Other
trends also exist, suggesting a complex history of fault-
ing and folding for the region.
The numerous carbonate bodies of the northern
Gabilan Range consist of limestone, dolomite, and,
more commonly, mixtures of limestone and dolomite
(plate 2). Limestone tends to be more varied in its
characteristics than dolomite, ranging from fine to
exceedingly coarse crystalline and white to light and
dark shades of blue gray. The dolomite is generally
medium to coarse crystalline and white, cream or light
blue gray. Both types of rock occur in pure masses,
although dolomite often appears as replacement pat-
ches or bands in limestone. In many cases, carbonate
rock is penetrated by dikes and fingers of granitic rock
or is interleaved with schist and gneiss. Other deleteri-
ous materials associated with limestone and dolomite
include quartz in the form of veinlets and replacement
masses and silicate minerals developed in impure car-
bonate rock or adjacent to granitic contacts.
The largest reserves of limestone are available at the
Bryan and Pearce-Twohy and the East Gabilan depos-
its, totaling an estimated 36 million tons. Ideal Cement
Company controls both deposits, the former being
worked until 1973 as a source of limestone for the
company's cement plant at San Juan Bautista. Lime-
stone reserves at the Upper Bird Creek, Blue Rock
Mountain, Garner-Harris, and Palmtag-Harris depos-
its possibly amount to several million tons each. Other
good-quality limestone deposits appear to be much
smaller, but may be useful for special purposes. The
Hamilton, A.S. and R., and Bardin Ranch deposits, for
example, may be useful sources for whiting and white
filler materials.
The Natividad and VVestvaco deposits, both actively
quarried as major sources of basic refractory raw
materials, probably are the largest pure dolomite
deposits in the Coast Ranges. Additional dolomite re-
serves are available at the Kaiser-Harris, Martin
Ranch, McCray Ranch, and possibly the Porter Ranch
deposits.
Large quantities of mixed carbonate rocks and im-
pure limestone and dolomite exist in the Fremont
Peak and Natividad areas. The development of these
deposits, without the aid of beneficiation, appears to
be limited to crushed rock uses. Some of the areas
designated as "c" on plate 2 have not been examined
carefully and may contain useful reserves of limestone
or dolomite.
The various deposits of the Gabilan Range district
are described alphabetically below.
A. S. and R. deposit. Location: W"/2 sec. 28 (proj.),
T. 1 3 S., R. 5 E., M.D., 5 miles south of Hollister at the
confluence of Bird Creek and North Canyon; Hollis-
ter 15-minute quadrangle. Ownership: Howard Har-
ris, 7800 Cienega Road, Hollister (1959).
The deposit was held by American Smelting and
Refining Company for many years prior to 1947, but
it was never developed or even significantly prospect-
ed. The A. S. and R. deposit has been examined and
described by Bowen and Gray ( 1959, p. 3 1 ) as follows:
1978
Limestone in the Coast Ranges
55
"Pure white, and blue-gray and white variegated, coarsely crys-
talline limestone is in a thin, lenticular, vertical-standing pendant
within granite and schist walls. It forms the crest of a ridge trending
N 65"-70' W and has little or no overburden. The limestone is
exposed for a length of 1,800 feet and an average width of 120
feet. A maximum of 200 feet of depth is exposed above the level
of Bird Creek but the pendant continues downward for an undeter-
mined distance. Accessible reserves in the lens probably exceed
1,000,000 tons. A few small granitic dikes penetrate the limestone
but are not believed to be a serious problem in quarrying. Most
of the limestone is white rather than colored. The following anal-
yses on samples collected by the authors and analyzed by Abbot
A. Hanks, Incorporated, are believed to be representative of the
variations found in the deposit."
Sample
Simple
Simple
Sample
Oxide
GP 1)
GP 14
G P IS
GP 16
CaO
54.48%
50.79%
47.80%
52 24%
MgO
3.43
3.89
6.26
0.73
SiO,
1.74
0.36
0.58
3.66
Fe.O,
0.19
0.17
0.17
0.23
AIA
0.29
0.25
0.27
0.73
PA
0.05
0.03
0.02
0.04
Recent investigations by Oliver E. Bowen, Thomas
H. Rogers and Marshall E. Maddock (unpublished)
indicate that the deposit is considerably smaller and
contains substantially less limestone than the original
estimate (Bowen, 1968, personal communication).
Considering the white color of most of the lime-
stone, the deposit may have use as a source of whiting
or for some other special purpose.
Barbee Ranch deposits. Location: SE'X sec. 9, T.
1 3 S., R. 4 E., M.D., 2 miles south of San Juan Bautista;
San Juan Bautista 15-minute quadrangle. Ownership:
Ideal Cement Company, 420 Ideal Cement Building,
Denver, Colorado 80202 (1959).
Large blocks and boulders of crystalline limestone
were quarried in a minor way many years ago in a few
places in the vicinity of SE1/ sec. 9 on the Barbee
Ranch. Limestone detritus of the Sur Series consti-
tutes a large percentage of reddish nonmarine breccias
and conglomerates that occur as thick lenses in the
Yaqueros Formation of early Miocene age. These
lenses are interbedded with fossiliferous sandstone
and constitute a unit as much as 1,000 feet thick. Con-
centrations of fragmental limestone extend westward
for 5 miles between N W'/4 sec. 14, T. 1 3 S., R. 4 E., and
N'/« sec. 12, T. 13 S., R. 3 E. (Allen, 1946, p. 28-30).
Three limestone samples collected and analyzed by
the owner gave the following results (Bowen and
Gray, 1959, p. 23):
Sample CM MgO M,(l Fe..O, h.O \a..O SiO~
1 54 86% 043% 126% 0.46% nd nd 146%
2 54.86 0.52 0.89 0.33 nd. nd. 1.06
3 51.02 0.57 1.73 0.75 0.06% 0.07% 5.10
Although limestone reserves may be large, expected
variations in limestone composition and dilution with
noncarbonate detritus may make this deposit unat-
tractive as a future source of limestone.
Bardin Ranch deposits. Location: SE'/, sec. 33 and
SW'/, sec. 34, T. 13 S., and NW'/( sec. 3, T. 14 S., R. 4
E., M.D., 9 miles northeast of Salinas; San Juan Bautis-
ta 1 5-minute quadrangle. Ownership: Bardin Ranch,
Salinas (1959).
Three patches of potentially commercial limestone,
situated about a mile west of Fremont Peak, have been
mapped by Bowen and Gray (1959, p. 28 and plate 1).
These patches are parts of two larger carbonate masses
of mixed limestone and dolomite of the Sur Series.
Bowen and Gray briefly describe the patches:
"Part of the rock in these deposits is medium-groined, blue-gray
material suitable for general use where color is not important, and
part is coarse-grained, pure-white material suitable for whiting and
white filler. None of the deposits has been developed or tested
except for a few samples token by the authors but, judging from
surface exposures, more than a million tons of commercial material
might reasonably be developed in the three masses. They ore
currently accessible by Gabilan Creek Canyon via an unimproved
dirt road."
Bird Canyon Ledge. Location: SE1/ sec. 31
(proj ), T. 13 S., R. 5 E., M.D., 7 miles southwest of
riollister; Hollister 15-minute quadrangle. Owner-
ship: Ideal Cement Company, 420 Ideal Cement Build-
ing, Denver, Colorado 80202, holds the mineral rights
(1959).
Old Mission Portland Cement Company, predeces-
sor to the present owner, acquired and drilled the Bird
Canyon Ledge in 1925 in order to increase their re-
serves of cement raw materials. The deposit has been
mapped and described in some detail by Bowen and
Gray (1959, p. 31-32, plate 1):
"The Bird Canyon Ledge occupies the south slope of a ridge
trending N. 65° E. The north border of the principal limestone moss
lies close to the ridge crest. The south border, which is more regular,
lies close to the canyon bottom. In plan the deposit is about 600
feet long parallel to the ridge and 800 feet long perpendicular to
the ridge. From ridge crest to creek bottom, a depth of 560 feet
of limestone is exposed. The predominating surface trace of well-
developed joints in the limestone strikes N 55c-60° E and the joint
surfaces dip very steeply southeast, but it is doubtful if this repre-
sents bedding. Bonafide bedding was not observed in the main
mass. The limestone is bounded on the north and south by quartz-
mica schist and granite; on the east by granite; ond on the west
by a mass of gray replacement silica. From exposures seen along
the creek the deposit bottoms in granite and silica and the chances
of it continuing down below the level of the creek bottom are small.
Roughly 10,000,000 tons of carbonate rock are present in the main
mass but there is some question as to whether all of this is suitable
for manufacture of portlond cement "
The analyses in table 1 1 indicate the deposit to be
too high in magnesia for use in Portland cement. The
deposit is undeveloped.
Bluerock Mountain deposit. Location: SW1/ sec.
25 and SE % sec. 26, T. 14 S., R. 4 E., M.D., 9 miles east
of Salinas and nearly 8 miles north and slightly east of
Chualar; Gonzales 1 5-minute quadrangle. Ownership:
Not determined.
This deposit lies on the rugged west slopes of Blue-
rock Mountain. It is briefly described by Bowen and
Gray ( 1959, p. 37) as "an oval mass having a slight east
elongation and underlies most of the SW'/4 sec. 25 ... .
56 California Division of Mines and Geology Bull 197
Table 11. Chemical analyses of samples from the Bird Canyon Ledge (after Bowen and Gray, 1959, p. 32).
Ignition
loss
(chiefly
Sample
CaO
MgO
Si02
FenOi
PnOs
G-21
51.20%
3.25%
7.36%
0.19%
0.39%
ND
0.14%
0.05%
37.88%
G-22
50.00
3.26
3.72
0.23
0.35
ND
0.09
0.03
42.21
G-23
35.60
17.54
9.96
0.73
0.89
ND
0.05
0.05
34.27
G-24
41.70
14.94
2.12
0.12
0.22
ND
0.03
0.01
39.68
G-25
39.00
19.13
4.86
0.39
0.51
ND
0.03
0.01
34.66
G-26
39.10
13.74
4.00
0.53
1.05
ND
0.05
0.10
39.68
G-42
53.93
1.21
0.80
0.05
0.20
0.03%
ND
ND
ND
G-43
54.83
0.80
0.10
0.05
0.02
0.27
ND
ND
ND
G-44
43.38
0.15
17.90
0.02
3.67
0.01
ND
ND
ND
G-45
46.17
7.84
0.81
0.03
0.21
0.01
ND
ND
ND
G^6
42.29
7.38
6.22
0.25
1.80
0.17
ND
ND
ND
G^7
36.86
13.95
3.72
0.13
0.70
0.10
ND
ND
ND
G-48
46.64
4.45
6.04
0.16
0.68
0 14
ND
ND
ND
G-49
44.74
6.79
4.24
0.14
1.16
0.56
ND
ND
ND
G-50
29.64
18.57
7.06
0.17
0.83
0.10
ND
ND
ND
G-51
34.63
17.54
0.12
0.03
0.03
0.02
ND
ND
ND
G-52
38.00
11.37
6.04
0.03
1.79
0.07
ND
ND
ND
G-53
50.95
1.91
3.52
0.02
0.42
0.16
ND
ND
ND
G-54
35.88
16.78
0.28
0.02
0.12
0.01
ND
ND
ND
G-5S
4945
5.34
0.32
0.01
0.07
0.03
ND
ND
ND
ND = N'ot dune
Samples G-21 through G-26 were analyzed by L A Caeiano, Ideal Cement Company. San Juan Bautista Samples G-42 through G-55 were analyzed by Abbot
A Hanks, Inc , San Francisco, 1958.
Most of the mass appears to be medium crystalline,
blue-gray limestone. Reserves probably aggregate
many millions of tons." Although the deposit is un-
developed, it appears worthy of some future sampling
and exploration in order to assess the potential re-
sources. It is accessible by dirt roads from the Salinas
Valley.
Bryan and Pearce-Twohy (Ideal Cement Com-
pany) deposit. Location: N'/2 sec. 24 (proj.),
T. 13 S., R. 4 E., M.D., 5 miles southeast of San Juan
Bautista; Hollister 1 5-minute quadrangle. Ownership:
Ideal Cement Company, 420 Ideal Cement Building,
Denver, Colorado 80202, holds mineral rights (1963).
In 1927, Pacific Portland Cement Company (prede-
cessor to present owner) acquired the holdings of Old
Mission Portland Cement Company and intensively
prospected this deposit by core drilling and surface
sampling. Later (1941?), a quarry was developed to
provide limestone for renewed cement manufacture.
The plant was shut down between 1930 and 1941. The
plant closed again in 1943 but reopened in early 1947.
Shortly thereafter, the Bryan and Pearce-Twohy
deposit became the principal source of limestone used
at the cement plant near San Juan Bautista.*
The deposit consists of two adjacent masses of crys-
talline limestone associated with schist of the Sur Se-
ries and cut by intrusions of granitic rocks. An early
map of the deposit (Pacific Portland Cement Com-
pany, 1927, unpublished) shows the largest mass to be
northwest-trending and irregular in plan. It has a
•Quarry operations ceased about lu7.t (see Ideal Cement Company — San
Juan Bautista footnote on p. 63).
length of 2,300 feet and an average width of about 400
feet and is exposed through at least 550 feet of relief.
A smaller mass, roughly 600 by 500 feet in plan, is
situated immediately west of the main mass. Lime-
stone beds in the main mass generally dip 20° to 50° S,
being steeper to the south, and probably represent 200
to 300 feet of stratigraphic thickness. Apparently the
deposit is somewhat broken by faulting, as indicated
by the presence of breccia and fault gouge in the quar-
ries. The limestone is medium to coarsely crystalline,
white to blue gray, and uniform in appearance and
chemistry. The average analysis of 50 surface samples
and 500 feet of diamond drill cores, sampled and
analyzed by Ideal Cement Company, shows 51.1%
CaO, 1.4% MgO, 41.7% C02, 4.1% Si02, and 1.7%
Fe203and A1203 (Bowen and Gray, 1959, p. 25). Based
on the dimensions of the limestone masses, limestone
reserves are estimated to be 8 to 9 million tons per
hundred feet of depth. Granitic intrusives and other
noncarbonate rock inclusions reduce reserve esti-
mates significantly, but to an unknown extent. Bowen
and Gray (1959, p. 25) estimate total reserves to be
about 20 million tons; but, due to unfavorable strip-
ping ratios, part of the limestone is not recoverable by
surface methods.
Development of the deposit is centered in two quar-
ry areas in the main limestone mass. According to
Oliver E. Bowen ( 1963, personal communication), the
largest quarry is situated along the crest of the main
east-trending ridge. In 1961, it was reported to be
about 1200 feet long by 200 to 300 feet wide. A smaller
quarry to the southeast covered an area roughly 800
feet long (east-west) by 100 to 200 feet wide. The
1978
I.IMFSIOM IN THE COAST RANGES
57
limestone is worked by benching at 30- to 50-foot in-
vervals. After preliminary crushing and screening at
the quarries, the limestone is trucked about 6 miles to
the company plant (see Ideal Clement Company, San
Juan Bautista plant). At one time rail facilities con-
nected the plant with the deposit.
Buzzard's Roost deposit. Location: E'/2 sec. 14,
T. 14 S., R. 5 E., M.D., 91/, miles south of Hollister;
Gonzales 15-minute quadrangle. Ownership: S. H.
Cowell Foundation, 2 Market Street, San Francisco,
and possibly others (1962).
Bold, craggy outcrops of carbonate rock are exposed
at and near the summit of a 2645-foot peak, locally
known as Buzzard's Roost. The mass is not readily
accessible and has not been examined but is reported
to consist of crystalline limestone of the Sur Series. As
viewed from the east, the limestone appears to extend
to the north as a persistent ledge near the crest of a
north-trending spur. The mass extends over a length
of half a mile and apparently is gently dipping. A
smaller lens of carbonate rock lies a few hundred feet
southeast of the main mass on a spur of the peak.
These bodies are shown as a single large mass by R. E.
Dempster (unpublished mapping shown by Jennings
and Strand, 1958). The deposit may contain several
million tons or more of limestone and would certainly
warrant close examination and sampling. It is most
accessible from the south, lying about half a mile
north of the dirt road to the Hamilton deposit.
Chalone Creek deposit. An undeveloped lime-
stone deposit reportedly located 6 miles east of Metz
in the southeast part of T. 17 S., R. 7 E. (Gonzales 15-
minute quadrangle) in Monterey Countv is men-
tioned by Logan (1947, p. 259). The deposit was not
located. However, several small, scattered bodies of
Sur Series limestone are shown by Jennings and
Strand ( 1958) to lie 5 to 9 miles north of Metz. These
were not examined.
Cowell-Thompson Greek deposit. Location: N'/2
sec. 30, T. 14 S , R. 6 E., M.D., 11 miles south of
Hollister; Gonzales 15-minute quadrangle. Owner-
ship: S. H. Cowell Foundation, 25 California Street,
San Francisco (1959).
This deposit, located on the north side of Thompson
Creek, was developed in 1885 by J. J. Bart who cal-
cined the limestone in two upright kilns (Irelan, 1888,
p 488). The property was also operated in the 1890s
by Cienega Lime Company which operated four con-
tinuous kilns. No additional work has been done since
the property was acquired by Cowell Lime and Ce-
ment Company about 1900.
The Thompson Creek deposit is reported by Bowen
and Gray ( 1959, p. 37) to be a sheetlike mass that dips
steeply north. It is exposed on steep terrain over a
length of half a mile and a width of 60 to 100 feet. The
limestone is white to blue gray, medium to coarse
crystalline, and apparently low in impurities, al-
though no analyses are available. Granite dikes and
schist interbeds exist at numerous places. Although
this deposit may contain several million tons of lime-
stone, only a small percentage of that could be ob-
tained by surface quarrying because of the relation of
the steep topography with the attitude of the thin lens.
Selective mining probably would be necessary to
maintain a uniform grade of rock.
Other references: Crawford, 1896, p. 629; laizure, 1926, p. 237, Logon,
1947, p. 276.
Crowe Ranch deposits. Limestone and dolomite
deposits, mentioned by Logan (1947, p. 274, 278) as
part of the Cassie Crowe holdings east of Fremont
Peak in San Benito County, are described herein as the
A. S. and R., Bird Canyon Ledge, Garner-Harris, Har-
mony Hills, Kaiser-Harris, Middle Dam, and Palm-
tag-Harris deposits.
East Cabilan deposit. Location: SWJ/4 sec. 36
(proj.), T. 13 S., R. 4 E., M.D., 1 mile east and slightly
south of FYemont Peak and 7 miles southeast of San
Juan Bautista; Hollister 1 5-minute quadrangle. Own-
ership: Rollin Reeves Ranch, Salinas (mineral rights
leased to Ideal Cement Company, 1959).
According to Bowen and Gray ( 1959, p. 28, 30, plate
1 ), "the East Gabilan deposit is the largest in the Fre-
mont Peak district and is situated on terrain favorable
to low-cost quarrying." The deposit is a relatively
pure limestone portion of a large bodv of mixed lime-
stone and dolomite. Bowen and Gray further describe
the deposit as follows:
"As seen in plan, the limestone mass averages about 300 feet
in width and is approximately 2,800 feet long. The beds, though
crudely defined, strike N. 70-80° w., and dip 65-80° N. Erosion
has exposed limestone to a depth of 140 feet below the highest
outcrops and the mass has been penetrated by several hundred
feet of adits, driven for sampling purposes by predecessors to Ideal
Cement Company. Although overlain strotigraphically by dolomite
and dolomitic limestone, the stratigraphic sequence dips too steep-
ly for such material to cause an overburden problem. Over most
of the deposit there is no overburden whatever. Estimated reserves
calculated to a depth of 240 feet below the uppermost outcrops
(a reasonable recovery depth) total approximately 16,000,000
tons. Substantial additional tonnage could be developed by under,
ground mining methods."
The analyses in table 12 are typical of the limestone.
Toble 12. Chemical analyses of limestone from East Gabilon
deposit, Monterey County (after Bowen and Gray, 1959, p. 31).
(hide
#/
*2
#.'
#4
#S
#6
* "
CaO
55.42%
54.42% 54.71% 54.4}% 54.37%
54.35% 54.02%
MgO
0.41
0.92
0.41
0.53
0.45
0.48
0.99
SiO,
0.24
0.94
1.52
0.86
0.86
0.92
0.82
Fc.O,
0.20
0.14
0J2
0.11
0.08
0.11
0.13
AI.O,
0.10
0.14
0.}4
0.29
0.26
0.17
0.13
K,0
0.03
0.02
0.06
ND
ND
ND
ND
Na,0
0.04
0.0}
0.02
ND
ND
ND
ND
PA
ND
ND
ND
0.06
0.03
0.02
0.02
Ignition loss
(chiefly CO,) ...
. 43.72
43.5}
43.18
ND
ND
ND
ND
ND — noi done.
Samples 1-1 were analyzed by Ideal Cement Co.; samples 4-7, by Abbot A
Hanks, Inc.
58
California Division of Mines and Geology
Bull 197
Flint-Steinbeck deposit. Location: S'/2 sec. 23, T.
13 S., R. 4 E., M.D., 4'/2 miles south-southeast of San
Juan Bautista; San Juan Bautista and Hollister 15-
minute quadrangles. Ownership: Ideal Cement Com-
pany, 420 Ideal Cement Building, Denver, Colorado
80202 (1959).
This deposit was a principal source of limestone
used in cement manufacture near San Juan Bautista in
the 1920s and 1940s. Limestone was produced from
quarries on both sides of a north-trending ridge and
transferred to the plant via a narrow gauge railroad.
The deposit has not been worked in recent years.
Since about 1950, the Bryan and Pearce-Twohy depos-
it, located V/2 miles to the northeast, has been the
major source of limestone used at the plant. Bowen
and Gray ( 1959, p. 25) describe the deposit as follows:
"Limestone occurs in a long thin lens, set on edge, the edge
trending N. 80° E. The sheetlike moss, tapered at both ends, dips
steeply south, has a traceable length of nearly 3,000 feet and an
average width of about 100 feet. It has been exposed to a max-
imum depth of 440 feet by erosion but probably continues below
the level of the adjacent canyon-bottoms. Wall rocks are granite
and quartz-mica schist. The limestone is similar in physical charac-
ter and chemical content to the rock from the Bryan and Pearce-
Twohy properties. Considerable limestone remains in the lens but
recovery would be expensive because of the attitude of the mass
and because of the steepness of the topography. Much of the
remaining material would have to be mined underground or else
stripped at high cost."
Other references: Laizure, 1926, p. 226; Logon 1947, p. 276.
Fremont Peak deposit. Location: S'/2 sec. 35
(proj.), T. 13 S., R. 4 E., M.D., about a quarter mile
south and east of Fremont Peak and 6'/, miles south-
southeast of San Juan Bautista; San Juan Bautista and
Hollister 15-minute quadrangles. Ownership: Reeves
Ranch and Bardin Ranch (1959).
This deposit consists of four substantial masses of
medium- to coarse-crystalline, pale blue-gray lime-
stone grouped about the south flank of Fremont Peak.
These masses have been mapped and briefly described
by Bowen and Gray (1959, p. 31, plate 1), who esti-
mate the probable total reserves to be a million tons.
Three samples of representative limestone were
analyzed by L. A. Caetano of Ideal Cement Company.
The analyses are given below:
Sample Sample Sample
Oxide GJJ Glf
CaO 55.02% 5i.94% 55.52%
MgO 0.69 1.53 0.46
SiO, 1.58 0.42 0 14
Al,0, 0.58 0.08 0.17
Fe,0, 0.30 0.08 0.13
K,0 0.03 0.01 0.01
Na,0 0.04 0 01 0.04
Ignition loss
(chiefly CO,) 42.14 43 62 43.60
In addition to the main limestone deposits described
above, small masses of relatively pure dolomite and
limestone a short distance to the south and east have
been mapped by Bowen and Gray, some of which may
warrant future prospecting.
Gamer-Harris deposits. Location: Sl/2 sec. 34
(proj.), T. 13 S., R. 5 E., M.D., three quarters of a mile
west of Vineyard School and 6 miles south of Hollis-
ter; Hollister 15-minute quadrangle. Ownership:
Howard Harris, 7800 Cienega Road, Hollister, owns
the old Garner property west of Bonanza Gulch
(1962).
Several medium-sized to small masses of crystalline
limestone lie on the north and east flanks of a 1,916-
foot hill (see geologic map, plate 2). The limestone
bodies, which are interbedded with schist and intrud-
ed by granitic rocks, generally trend west-northwest.
The limestone is typically medium to coarse crystal-
line, blue gray to off white, and frequently banded,
mottled, or brecciated. Some dolomite is present as
thin bands of near-white, medium-crystalline rock in
the limestone. Heavy soil, caliche, and vegetation ef-
fectively mask the extent of the deposits. However,
prospecting has helped to define the deposit bounda-
ries.
Development of the deposits has been limited to
shallow prospect cuts and some stripping. A series of
137 samples, collected at regular intervals and
analyzed by the owner, indicate the deposits to be of
variable composition. Analyses, kindly furnished by
the owner, are given in table 1 3. Possibly 3 or 4 million
tons of limestone are present here, but much of this
would have to be mined selectively due to local con-
centrations of dolomite and granitic impurities. From
an economic viewpoint, the Garner-Harris deposits
would appear to be useful mainly as a reserve source
of cement raw material. Four of the larger deposits,
examined in October 1962, are discussed below.
Big Flat deposit. This deposit is located in S'/2SE'/4
sec. 34, 3,000 feet southwest of Vineyard School. It is
pear-shaped in plan, with maximum dimensions of
800 feet by 500 feet and is exposed through 300 feet of
relief. A thick surficial layer of caliche masks much of
the lower part of the deposit, even where prospect cuts
exist. Where exposed, the limestone is light to dark
gray, medium crystalline, partly brecciated, and local-
ly siliceous. Some white, iron-stained dolomite exists
on the north side of the mass. In table 13 a series of
samples (BFA, BFB, BFC, BFD), collected and
analyzed by the owner, indicate the limestone to be
low in MgO but to contain variable amounts of Si02,
Al20,, and Fe20,. Samples BF 1-16 represent the
chemical variations of the caliche. If the analyses are
representative of the deposit as a whole, use of the
limestone is probably limited to cement manufacture.
Reserves of limestone, including impurities and gra-
nitic dikes, are estimated to be no more than 18,000
tons per foot of depth.
Dry Trough deposit. The deposit is located in
SW'X sec. 34 (proj.), 4,500 feet west of Vineyard
School. It trends N 70° W and consists of limestone
and some dolomite exposed over an area having max-
imum dimensions of 1,300 feet by 400 feet with 250
1978
Limestone in hie Coast Ranges
59
feet of relief. Medium- crystalline, blue-gray, some-
times banded or variegated limestone is the chief rock
type. W hite medium-crystalline dolomite exists in
thin bands near the north and south margins of the
mass. The limestone is farther from the San Andreas
fault zone and is generally less brecciated than other
deposits in the Garner-Harris group. Development is
limited to several prospect cuts from which the owner
has collected 20 samples for analysis (see DT and DT
2 series in table 13). With the exception of one dolo-
mite sample ( DT2 1 ) , the analyses show an average of
about 51% CaO and 4% SiO,. Total carbonate rock
reserves are estimated to be no more than 15,000 tons
per foot of depth. Selective mining would be necessary
to develop the deposit, and recoverable reserves may
be less than indicated.
West Boundary deposit. A poorly exposed mass
of limestone trending N 70° W is situated a few hun-
dred feet northeast of the Dry Trough deposit. It ex-
tends over an area 1,700 feet long by a maximum of 250
feet wide. Smaller bodies of carbonate rock lie close by
to the southwest and east. The limestone is mainly off
white, medium to coarse crystalline, and partly brec-
ciated. Although outcrops are scattered, prospect cuts
and stripping partly define the mass. In recent years,
Howard Harris has collected and analyzed 36 samples
from this deposit (see samples of WB and G series,
table 13). Chemical analyses indicate that the lime-
stone contains variable amounts of silica and little
magnesia (two exceptions). Total reserves appear to
run about 12,500 tons or less per foot of depth.
Blue deposit. This small lenticular mass trends N
70° W and lies just east of the Dry Trough deposit.
Maximum dimensions are about 700 feet by 125 feet.
It consists of light-gray to blue-gray, medium-crystal-
line limestone containing some thin bands of white
dolomite. Development is limited to several shallow
prospect cuts from which 15 samples were obtained
for analysis (B and BA series, table 13). Estimated
reserves are less than 5,000 tons per foot of depth.
Considering the variable chemical composition of the
samples and apparent small reserves of limestone, the
deposit would not appear to be of significant commer-
cial value.
Reference: Bowen and Gray, 1959, p. 33.
Hamilton deposit. Location: N'/2 sec. 23, T. 14 S.,
R. 5 E., M.D., 10 miles south of Hollister; Gonzales
1 5-minute quadrangle. Ownership: Mrs. A. E. Hamil-
ton, Cienega Road, Hollister (1962).
This deposit includes three closely grouped lenses
of limestone, each of which has been developed to
some extent. There is some confusion in the literature
regarding ownership, operations, and locations. Lime-
stone property in sec. 23 has been owned at various
times by U. G. Harlan; San Benito Lime Company
(Connelly and Kruse); Archer Lime Company (D.
McPhail); Hamilton, Fontaine, and Temple; W. R.
Fontaine; and Marie Mayries. From 1890 to about
1907, limestone was quarried and burned locally by U.
G. Harlan and probably even earlier by San Benito
Lime Company (Bradley and Logan, 1919, p. 340, 342;
Averill, 1947, p. 51-52). The San Benito Lime Com-
pany deposit apparently was acquired about 1925 by
Hamilton and associates and worked as a source of
lime rock and agricultural limestone from 1930 to
1932. During the 1950s and early 1960s, A. E. Hamil-
ton did considerable development work but was una-
ble to realize commercial production in recent years.
At the time of his death in 1962, a crushing-screening
plant, located just east of the main lens, was well to-
ward completion. A jaw crusher at the plant has a
capacity of 200 tons per hour.
The Hamilton deposit is situated on a 2,83 1-foot hill
just north of Harlan Creek. It consists of three elon-
gate lenses extending half a mile north and slightly
east of the center of sec. 13. Perhaps the largest lens
occupies the north half of the deposit and is about
1,300 feet long by a maximum of 275 feet wide. A few
hundred feet to the south are two adjacent, parallel
lenses, each about 1,000 feet long by 100 to 150 feet
wide. Smaller masses of carbonate rock exist to the
east and west. The various lenses consist mainly of
white, extremely coarse-crystalline limestone associat-
ed with white to cream, medium-crystalline dolomite,
particularly near the margins. "The country rock and
the numerous dikes that cut the lenses are granodior-
ite, now decomposed.
The north lens trends north-northeast, is slightly
arcuate in plan, and appears to dip steeply to the east.
It is developed at its south end by a small quarry, a
275-foot tunnel, and prospect cuts near the summit of
the hill. The limestone contains scattered graphite
crystals and small amounts of white, finely fibrous
tremolite asbestos distributed along shear planes. A
typical sample of the coarse-crystalline limestone, con-
taining minor graphite and tremolite, was analyzed by
Lydia Lofgren in 1963. It contained 53.6% CaO, 1.53%
MgO, 0.56% SiO,, 0.06% A120„ 0.05% Fe20„ 0.01%
P,0,, and 43.62% ignition loss. The lenticular body is
locally dolomitic at its northeast end and west mar-
gins. Estimated reserves of limestone are on the order
of a million tons.
Two parallel lenses constitute the south half of the
deposit. The east lens was developed by a small quarry
near its north end. Here the limestone is white but
locally discolored, and some dolomite is present along
the west margin. The lens strikes N 10° E and dips
about 60° E. In addition to the quarry, the body is
developed by several prospect cuts.
Immediately to the west is a parallel, somewhat
thinner lens that appears to have an average width of
less than 100 feet. This body may be a detached exten-
sion of the main mass a few hundred feet to the north.
In the quarry exposures at the south end of the lens,
the limestone appears to dip steeply east and is trun-
cated on the down-dip side by granitic rocks. The
5 — 89454
60
California Division of Mines and Geology
Table 13. Chemical analyses of Garner-Harris deposits, San Benito County, by Howard Harris, owner.
Bull. 197
Simple
SiQ2
CaO
MgO AlsOiFezOj
Sample
SiO,
CaO
MgO AlsPa.FeiOa
4.0
51.89
0.31
0.5
2.9
51.92
0.44
1.7
2.3
51.39
0.44
1.7
3.0
50.83
0.19
1.8
2.8
52.86
0.44
0.9
3.0
50.31
0.41
1.8
3.0
50.52
0.67
1.5
Top of ridge
5.5
3641
12.70
1.5
4.9
50.52
7.37
1.0
3.9
53.50
0.75
1.0
4.6
51.26
0.58
1.4
11.9
46.10
0.58
1.9
6.8
51.56
0.50
0.9
4.9
52.35
0.40
0.7
3.0
51.29
0.29
0.7
3.6
48.10
0.36
0.7
3.7
51.55
1.40
0.7
EST BOUNDARY DEPOSIT
18.80
42.50
0.28
2.00
4.90
51.50
0.72
1.50
17.80
43.40
0.28
2.20
5.10
51.90
0.28
1.00
3.90
52.90
0.36
0.90
0.50
34.00
18.65
0.40
0.70
53.70
1.37
0.50
1.50
54.30
0.61
0.50
4.20
52.70
0.32
0.70
11.05
48.55
0.21
3.80
4.25
53.60
0.36
1.35
4.85
51.15
0.21
1.35
3.15
53.30
0.18
1.40
3.25
52.55
0.43
111
2.20
54.00
0.37
0.92
2.75
55.00
0.01
0.58
4.30
53.80
0.08
0.79
5.75
52.10
0.28
1.39
15.50
44.64
0.009
2.26
30.67
37.30
0.21
1 16
9.24
49.20
0.32
0.96
7.42
45.45
5.40
0.96
1.70
54.20
n on
0.40
1.00
55.60
u.oo
0.20
1.10
54.40
1 Cti
ft 7ft
u.zu
3.30
54.30
U > 1
040
1 60
54.70
0.51
0.40
1.60
55.10
0.72
0.30
4.30
54.10
0.62
1.10
2.00
54.12
0.51
0.60
2.20
53.53
0.50
0.60
22.00
41 SO
0.36
1 90
10.50
48.50
0.37
1.20
5.50
51.60
0.39
1.10
5.10
52.00
0 41
1.20
33.00
36.60
0.42
1.90
BLUE
DEPOSIT
2.00
53.70
0.34
0.70
16.00
31.25
12.00
1.00
2.15
49.35
3.90
0.80
0.95
54.05
0.90
0.55
1.70
40.20
11.00
1.30
2.55
53.20
0.50
0.90
3.30
49 90
1.90
0.70
2.00
53.60
1.20
0.40
2.20
53.50
0.39
0.45
3.90
53.00
0.11
1.10
3.50
53.00
0.34
1.20
0.60
33.10
18.96
0.90
0.60
40.10
12.96
0.40
3.20
53.10
0.07
0.80
3.10
53.80
0.05
0.70
BIG FLAT DEPOSIT
BFA 1
BFA 2 ...
BFA 3 ...
BFA 4
BFA 5 ...
BFA 6
BFA 7
BFA 8
BFA 9 ...
BFA 10 .
BFA 11
BFA 12
BFA 13
BFA 14
BFA 15
BFA 16
BFA 17
BFA 18
BFA 19
BFB 1.
BFB 2....
BFB 3....
BFB 4
BFB 5
BFB 6
BFB 7
BFB 8 ....
BFB 9....
BFB H)
BFB 11
BFB 12
BFB 13
BFC 1
BFC 2
BFC 3
BFC 4
BFC 5
BFD 1
BFD 2
BFD 3
BFD 4
BFD 5
BFD 6
BFD 7 ...
BFD 8
BFD 9
BFD l()
BFD II
BFD 12
BFD 1!
BFD 14
BF 1 ...
BF 2
BF 3
BF 4
BF 5 ....
BF 6
BF 7
BF 8
BF 9
BF 10.
BF 11
BF 12
BF IS
BF 14
BF 15
BF 16.
DT 1
DT 2
DT 3
5.00%
55.8 %
0.42%
1.40%
6.40
50.5
0.42
1.40
4.60
52.5
0.39
0 80
3.80
52.3
0.39
1.00
2.50
53.8
0.30
0.80
2.60
53.70
0.30
1.00
3.40
52.20
0.45
1.30
5.00
53.00
0.42
1.30
2.50
52.70
0.39
0.90
5.00
51.90
0.28
1.30
2.70
53.00
0.36
1.00
3.20
52.20
0.80
0.70
3.20
52.20
0.80
0.60
0.90
54.00
0.72
0.30
1.50
53.40
0.85
0.60
0.60
53.00
1.25
0.50
1.50
52.30
1.95
0.20
0.80
52.80
1.80
0.30
0.80
52.20
2.20
0.15
3.30
52.70
0.70
0.80
3.10
52.50
1.08
0.80
9.70
48.30
0.65
1.70
4.80
51.40
0.70
1.50
33.30
32.90
1.25
3.90
36.30
27.90
0.95
7.30
37.40
28.70
0.90
440
7.90
49.10
0.90
1.70
20.10
42.10
0.07
2.30
69.70
13.80
0.12
3.60
84.60
2.40
0.11
8.10
25 30
35.90
0.10
5.00
5.70
50 40
0.09
1.90
3.00
51.80
0.90
[.10
1.20
54.00
0.90
0.70
2.20
52.50
1.15
0.90
3.40
52.50
0.60
1.10
3.20
51.40
0.60
0.90
1.20
53.60
0.90
0.50
2.40
52.60
0.60
1.00
2.60
52.80
0.30
1.00
3.80
52.90
0.30
1.20
4.50
50. 50
0.30
1.30
3.20
51.25
0.15
0.80
2.90
51.55
Tr.
0.70
2.30
51.71
Tr.
0.60
3.10
51.66
Tr.
1.00
4.4(1
50.49
Tr
1.20
3.20
50.76
Tr
1.10
2.80
52.40
Tr
0.90
5.90
49.68
Tr
1.20
2.40
52.10
Tr.
1.00
at base of hill. Big Flat deposit
10.5
52.00
0.68
3.00
12.50
46.2
0.72
3.00
12.2
45.05
0.46
3.74
9.75
48.55
0.72
2.62
12.1
44.1
2.25
3.85
23.9
35.95
114',
6.3
20.35
40.06
0.52
3.2
21.35
38.00
Tr
3.35
26.0
28.02
0.58
2.9
20.2
37.05
0.52
6.75
15.23
40.02
0.68
2.77
13.25
45.00
0.93
2.73
11.70
42.45
0.07
6.9
8.00
51.05
0.07
4.7
11.60
4S 1
0.19
4.4
20.20
36.35
0.68
10.75
DRY TROUGH DEPOSIT
6.1
33.60
1.37
1.6
3.7
51.30
0.50
1.4
3.3
si 71
0.42
1.6
DT 4 ...
DT 5 ...
DT 6 ...
DT 7
DT 8 ...
DT 9 ...
DT 10
DT2 1 ...
DT2 2 ...
DT2 3 ...
DT2 4 ...
DT2 5 ...
DT2 6 ...
DT2 7 ...
DT2 8 ...
DT2 9 ..
DT2 10
G 1
G 2.
G 3.
G 4.
G 5.
G 6
G 7
G 8
G9.
GL 1..
GL 2..
GL 3..
GL 4..
WB 1
WB 2
WB 3
WB 4
WB 5
WB 6
WB 7
WB 8
WB 9
WBT 1 .
WBT 2
WBT 3
WBT 4
WBT 5 .
WBT 6.
WBT 7 .
WBT 8
WBT 9.
WBA 1
WBA 2
WBA 3
WBA 4
WBA 5 33 00
B 1 .
B 2
B 3
B4
B S
B6.
B 7 .
B 8 .
B 9
BA 1
BA 2
BA 3
BA 4
BA 5.
BA 6
1978
I.IMKSTONr l\ I 111 COASI RANG] S
61
Photo 10. Hamilton limestone deposit, upper prospect quarry, showing massive white crystalline limestone (left) and decomposed granite. Exploration tunnel
(center) runs westerly (toward left) through limestone cut by granitic dikes.
limestone is similar to the rest of the deposit, being
white and coarse crystalline. Recent surface develop-
ment has obliterated much of the old quarry, but the
limestone is exposed over a width of 60 feet and height
of 45 feet on the remaining face. The limestone appar-
ently supplied the two vertical stone lime kilns located
close by on Harlan Creek. Reserves of the two south-
ern lenses have not been determined but may aggre-
gate 500,000 tons or more.
Based on the chemical composition and the obvious
whiteness of the limestone, the I lamilton deposit may
prove useful as white filler, in glass manufacture, or
for other special purposes. In all probability, the
deposit would have to be mined selectively or bcncfi-
ciated or both in order to obtain a substantial produc-
tion of a uniform, high-quality product. Accessibility
is good via an improved dirt road, but rail facilities are
about 18 miles away at Hollister.
Other references Aubury, 1906, p. 76, Laizure, 1926, p. 237; logon, 1947,
p. 274-277, Bowen and Gray, 1959, p. 38.
Harmony Hills deposit. Location: SW'/i sec 17
(proj ), T. 13 S., R. 5 E., M.D., 5 miles southwest of
Hollister; Hollister 15-minute quadrangle. Owner-
ship: Howard Harris, 7800 Cienega Road, Hollister
(1966).
The Harmony I lills deposit is a small body of lime-
stone that may be of economic interest in the near
future because of its white color and easy accessibilii \
The body is lenticular in plan, striking northwest
along the crest of a small hill through a relief of 60 to
80 feet. It is at least 500 feet long and has a maximum
width of about 100 feet. Typically, the limestone is
white, medium to very coarse crystalline, and high in
calcium. There is local blue-gray mottling, and some
of the limestone is stained yellowish brown along frac-
tures and joints. Granitic rocks cut the deposit in sev-
eral places and probably comprise the country rock.
A typical clean limestone sample shows 52.37%
CaO, 2.60% MgO, 0.32% SiOj, 0.08% Fe20„ 0.14%
A1,0„ and 0.01% P20, (Bowen and Gray 1959, p. 25).
62
California Division of Mines and Geology-
Bull 197
1978
I l\tl S IONF l\ I Ml C().\S I K \\( ,1 s
63
Although exposures are poor and scattered, lime-
stone reserves appear to be no more than 100,000 tons.
Core drilling and sampling are needed to evaluate the
deposit more accurately. Since the deposit was briefly
examined by this writer in 1964, several bulldozer cuts
made by the owner in 1966 show that parts of the
deposit are not over a few feet thick (Oliver E. Bowen,
personal communication, 1968).
Hartnell group. Location: Mainly S'/2 T. 14 S., R.
4 E., M.D., 5 to 9 miles east and northeast of Salinas;
Salinas 15-minute quadrangle. Ownership: Multiple
(includes Sillacci Ranch, Walter Bardin Ranch, and
other properties).
The Hartnell group includes a northwest-trending
series of carbonate deposits lying in the northeast part
of the Salinas 15-minute quadrangle and close to the
old Hartnell College property. Based largely on un-
published mapping of Oliver E. Bowen (1968), the
gross distribution of the carbonate rock is shown on
plate 2. Some of the masses shown are exaggerated and
consist of smaller, detached lenses and bodies. The
carbonate rock is associated to some extent with schist
and other rocks of the Sur Series and together they
occur as northwest-trending pendants in granitic
rock. Based on the observations of Bowen (1968, per-
sonal communication) and of this writer, the deposits
are mostly small and often consist of mixed limestone
and dolomite. Some of the deposits are cut by granitic
dikes.
There has been only limited development of lime-
stone, principally (solely?) by Spreckels Sugar Com-
pany. Spreckels quarried limestone in NE1/ sec. 20
and NE'/i sec. 30, T. 14 S., R. 4 E. (proj.) , and possibly
elsewhere in the Hartnell group, for use in sugar proc-
essing and in the construction industry around the
turn of the century. Several prospect pits also were
developed by Spreckels in sec. 3, T. 14 S., R. 4 E. on
the Walter Bardin Ranch but were never worked com-
mercially. Production from the Hartnell deposits pri-
or to 1905 is estimated to be more than 50,000 tons of
limestone. Some limestone and associated granite
probably were produced in recent years from the low-
er Sillacci (Spreckels) quarry in NE1/ sec. 30 for use
as crusher run base material in road construction.
Most of the carbonate deposits in the Hartnell
group are too small or too impure to be of future
interest, but a few deposits have not been examined
carcfullv and warrant future consideration.
Other references: Aubury, 1906. p 73, Bowen and Gray, 1959, p. 37;
Hort, 1966b, p. 59.
Ideal Cement Company — San Juan Bautista
plant. Location: SE1/, sec. 4, T. 13 S., R. 4 E., M.D ,
1 mile south of San Juan Bautista; San Juan Bautista
15-minute quadrangle. Ownership: Ideal Cement
Company, 420 Ideal Cement Building, Denver, Colo-
rado 80202.
Construction of the San Juan Bautista cement plant
began in 1914 or earlier by Old Mission Portland Ce-
ment Company but was not completed until 1918. The
plant employs the wet process and has been operative
during the periods 1918 to 1930, 1941 to 1943, and 1947
to the present* In 1927, the plant was acquired by
Pacific Portland Cement Company, which merged in
1952 with Ideal Cement Company. Limestone utilized
in the manufacture of cement has been obtained from
several properties in San Benito County, including
the Barbee Ranch, Bryan and Pearce-Twohy, Flint-
Steinbeck, and Underwood deposits. Other nearby
deposits held by Ideal Cement Company include Bird
Canyon Ledge, Power Line(?), and Upper Bird Creek
in San Benito County and East Gabilan in Monterey
County. For deposit descriptions, the reader is re-
ferred to the above-named properties.
The San Juan Bautista plant utilizes about 220,000
tons of limestone and other raw materials per year
plus 40,000 to 60,000 tons of mudstone (Monterey For-
mation) from a quarry near Chittenden, Santa Cruz
County, to obtain the needed combination of lime,
silica, alumina, and iron oxide (Bowen and Gray,
1962, pt. 2, p. 5). These raw materials are crushed,
ground, blended, slurried, and converted to clinker in
four conventional kilns. The plant has a rated capacity
of 950,000 barrels of cement per year.
References-. Aubury, 1906, p. 184, Bradley and Logan, 1919, p. 626-630;
Logan, 1947, p. 276-277; Bowen and Gray, 1959, p. 23, 25; Bowen and
Gray, 1962, pt. 1, p. 7, and pt. 2, p. 4-5.
Kaiser-Harris deposit. Location: W'/2 sec. 3 and
E'/2 sec. 4, T. 14 S., R. 5 E. (proj.), M.D., 7 miles south
of Hollister; Gonzales 15-minute quadrangle. Owner-
ship: Kaiser Aluminum and Chemical Corporation,
300 Lakeside Drive, Oakland (1964).
This dolomite deposit is situated in the west corner
of the Garner-Harris Ranch immediately east of the
corner common to the Garner-Harris, Martin, Reeves,
and McCray Ranches (named counter-clockwise).
The common corner lies 2 miles west-southwest of the
Almaden Winery In 1943, Kaiser Aluminum and
Chemical Corporation (formerly Permanente Metals
Corporation) purchased 237 acres of dolomite prop-
erty from Cassie Crowe and Howard Harris after ex-
tensive drilling and trenching (Logan, 1947, p. 279).
There has been no production, and the deposit is held
as reserve to Kaiser's Natividad dolomite deposit 10
miles to the west in Monterey County. Dolomite from
the latter deposit is used extensively in the chemical
and refractory industries.
The Kaiser-Harris dolomite is white, coarse crystal-
line, and comprises the bulk of a small northeast-
trending pendant. The pendant is exposed over an
irregular area of about 40 acres, projecting salients to
the northeast and southwest. One small zone of me-
dium- to coarse- crystalline, gray, banded limestone
was noted near the projected E'/i cor. sec. 4, and others
may be present. Other deleterious features include
•The plant ceased operations in l°7i, apparently due to the high cost of
newly required pollution control equipment- The plant was subsequently
dismantled
M
California Division of Mines and Geology
Bull. 197
numerous granitic dikes and possible schist interbeds,
particularly in the topographically low areas. Two
samples, one (GP-23) analyzed by Abbot A. Hanks,
Inc., in 1955 and the other (KH-1) by the Division of
Mines and Geology laboratory in 1964, indicate the
high quality of the dolomite:
Ign.
Simple SiOs FeiOo AI2O3 CaO MgO PzQ5 Kfi loss
GP-2 3 .... 0.14% 0.11% 0.17% 30.80% 21.15% tr ivd nA
KH-1 1.40 0.12 0.00 31.00 20.00 0.02% 0.00% 46.10%
Sample GP-2 3 (Bowen and Gray, 1959, p. 35) is from
the central part of the pendant and KH-1 is from a
road cut in the main northeast salient.
Reserves of dolomite cannot be estimated without
more data. At the crest of the low spur near the south-
east boundary of the property, a drill hole reportedly
bottomed in dolomite at a depth of 180 feet. Consider-
ing that the pendant is exposed through nearly 1,000
feet of relief, accessible dolomite reserves may amount
to several million tons. Additional, but much smaller,
reserves are available to the northeast where a lens is
exposed in a roadcut near Nl/4 cor. sec. 3.
Los Vergeles deposits. Location: N'/2 T. 13 S.,
R. 3 E. and R. 4 E., M.D., 3 to 5 miles south and south-
west of San Juan Bautista; San Juan Bautista 15-
minute quadrangle. Ownership: Los Vergeles Rancho
in part (1959).
A series of small to medium-sized lenses and bodies
of carbonate rock comprise a gently sinuous belt that
lies mainly within the Los Vergeles Rancho in Monte-
rey and San Benito Counties. The belt extends 6 miles
eastward from S'/2 sec. 10, T. 13 S., R. 3 E. (proj.), near
Crazy Horse Canyon Road, to SE1/ sec. 15, T. 13 S.,
R. 4 E., near Queen Canyon (plate 2). The carbonate
rock is associated with other metamorphic rocks of the
Sur Series which occur as roof pendants in granodior-
ite (Allen, 1946, p. 20).
According to Bowen and Gray (1959, p. 23), the
carbonate rock consists largely of crystalline lime-
stone but is extensively contaminated with silica and
dolomite. The limestone varies from coarse to fine
crystalline and from blue gray to white. A select sam-
ple of white, coarse-crystalline limestone, collected
from the carbonate body crossed by San Juan Grade
road and analyzed by Abbot A. Hanks, Inc., in 1958,
contained 55.48% CaO, 0.25% MgO, 0.18% Si02,
0.03% Fe203, 0.08% A1203, and 0.02% P205. In spite of
the analysis, it is evident that careful sampling and
selective mining would be required to develop lime-
stone of uniform grade. The largest bodies reportedly
lie at the west end of the belt near Crazy Horse Can-
yon.
Apparently, there has been only minor develop-
ment of one of the deposits. A small tonnage of lime-
stone was produced from a quarry along the San Juan
Grade road near W1/ corner sec. 18, T. 13 S., R. 4 E.
(proj.). Some of this material was used by the Judson
Iron Works, presumably as a steel flux (Laizure, 1925,
p. 43).
Martin Ranch deposits. Location: Sees. 32, 33 and
34, T. 13 S., and N'/2 sec. 4, T. 14 S., R. 5 E. (proj.),
M. D., 6 to 7 miles south of Hollister; Hollister and
Gonzales 15-minute quadrangles. Ownership: Martin
brothers, 1215 Guarantee Savings Building, Fresno,
California (1966).
Numerous small to medium-sized bodies of crystal-
line dolomite and limestone lie on the 2,800-acre Mar-
tin Ranch. The dolomite deposits are largely confined
to the south part of the ranch in the vicinity of N'/2 sec.
4 (proj.). Limestone deposits lie north and northwest
of there — mainly in sees. 32 and 33 (proj.). The only
commercial development was by A. J. Fazzi who was
preparing to ship dolomite from an unidentified
deposit on the Martin Ranch in June 1916 (Bradley
and Logan, 1919, p. 635-636; Logan, 1947, p. 278).
The distribution of the Martin Ranch dolomite and
limestone, based largely on the detailed mapping of
Thomas H. Rogers (1968, unpublished map), is in-
dicated on plate 2.
The main dolomite deposit in NE'/i sec. 4, examined
briefly in February 1964, covers a north-trending area
about 1,200 feet long by at least 200 feet wide. The
deposit does not appear to be solid dolomite at its
north end, where it is bordered and intruded by gra-
nitic rock. To the south, the dolomite gives way to
limestone (see Reeves Northeast deposits). Most of
the dolomite is white and medium to very coarse crys-
talline. There is some iron oxide staining along joints
and fractures; otherwise, the dolomite appears to be of
uniform, high quality. The deposit was explored in
1956 by Westvaco Mineral Products Division, FMC
Corporation, who made five or six bulldozer cuts
across the long axis of the body. Four chemical analy-
ses of dolomite from the cuts were made by Abbot A.
Hanks, Inc., in 1958 (Bowen and Gray, 1959, p. 35)
and show the material to be of high quality:
S.imrlc ~s7>~; 1-cM). 1/jT 7^> \igO FT)-,
M.D. 1 0.26% 0.02% 0.06% 29.75% 22.19% 0.02%
M.D. 2 0.18 0.05 0.04 29.57 22.35 0.02
M.D. 3 0.44 0.01 0.08 29.71 22.13 0.01
M.D. 4 0.32 0.06 0.10 29.91 21.98 0.03
Another body of dolomite, exposed immediately to
the west, covers an irregular east-trending area with
maximum areal dimensions of 900 feet by 600 feet.
According to Thomas H. Rogers ( 1968, personal com-
munication), who mapped the northern part of the
mass, the dolomite is nearly white, coarse crystalline,
and pure. The outcrop pattern of the dolomite sug-
gests that the mass dips gently to moderately to the
north.
Dolomite reserves of the above deposits are undeter-
mined but could amount to several million tons. The
two dolomite deposits are reasonably accessible and
well situated for mining, being exposed through 200
to 300 feet of relief.
1978
Limestone i\ iiii Coasi Ranges
65
The main limestone deposits are centered on "hill
1981" about a mile north of the dolomite deposits.
Perhaps the largest limestone deposit covers an east-
trending area about 600 feet long by 300 feet wide on
"hill 1981." Part of this deposit is well exposed, con-
sisting of blue- gray, medium- to coarse-crystalline
limestone. According to Oliver E. Bowen (1968, per-
sonal communication), lenticular replacement
patches of dolomite a few inches thick and several feet
long are present but do not appear to make up a sub-
stantial volume of the mass. Patches and laceworks of
siliceous material indicate a probable silica content of
2 to 5%.
Many smaller lenses are present in the vicinity of
"hill 1981" and southwest of there (plate 2). Some of
these consist of relatively pure limestone and others
contain substantial amounts of dolomite and siliceous
impurities. Because of the apparent small sizes of these
limestone bodies and the abundance of quartz-mica
schist interbeds and granitic dikes, only three or four
of the larger bodies seem worthy of prospecting. Max-
imum reserves of economically recoverable limestone
probably do not exceed 1 or 2 million tons. None of
the Martin Ranch deposits had been explored by drill-
ing as of June 1969 (Thomas H. Rogers, 1969, personal
communication).
Other reference: Taliaferro, 1943, map.
McCrav Ranch deposits. Location,: E1^ sec. 4, T.
14 S., R. 5 E., M. D., V/i miles south of Hollister;
Gonzales 15-minute quadrangle. Ownership: Dr. Rol-
lin Reeves, Salinas (1964).
A nearly continuous succession of detached masses
of dolomite extend for half a mile in a northeast-trend-
ing zone in SE'X sec. 4. Actually, these masses may be
remnants of a single pendant connected with the Kai-
ser-Harris deposit to the northeast which is now cut
in numerous places by granitic rock.
Several salients of dolomite and a small zone of lime-
stone extend to the southwest into the McCrav Ranch
from the Kaiser-Harris pendant and, with one excep-
tion, none appears to be of sufficient size to be eco-
nomic. One salient of dolomite extends to the south
where it connects with a mass of dolomite that extends
about half a mile southwest to the edge of the Reeves
Ranch. The dolomite mass appears to be cut by nu-
merous granitic dikes so that it may actually consist of
a number of small disconnected masses of dolomite.
Much of the dolomite is white and of good quality.
During the early 1960s, the deposit was drilled and
acquired by Inorganic Chemicals Division of FMC
Corporation. Reserves of dolomite may be fairly large,
although considerable granitic material is probably
present.
No chemical analyses of the dolomite are available.
However, two samples of limestone collected at the
ridgecrest near E'/ cor. sec. 4 were shown to be of high
grade, based on chemical analyses by Abbot A. Hanks,
Inc. (Bowen and Gray, 1959, p. 36). The limestone is
medium to coarse crystalline, light gray to blue gray,
banded, and platy. The limestone mass is probably too
small to be of significant commercial value.
McPhail deposit. Location: SE'/4 sec. 13, T. 14 S.,
R. 5 E. and SW'/4 sec. 18, T. 14 S., R. 6 E., M.D., 10
miles south-southeast of Hollister; Gonzales 15-
minute quadrangle. Ownership: Amy McPhail of
Hollister and others.
An undeveloped deposit of crystalline carbonate
rocks of the Sur Series is shown by R. E. Dempster
(unpublished mapping shown in Jennings and
Strand, 1958) as occupying the summit of a 2,240-foot
hill. The deposit is shown to trend northwest and to
cover an irregular area of half a mile by a quarter of
a mile. From a distance, the deposit appears to consist
of several detached masses of carbonate rock as in-
dicated by sporadic outcrops. Close examination is
needed to determine the nature of the deposit and the
advisability of additional prospecting. Dirt roads lead
from Cienega Valley, via Indian Canyon or Thomp-
son Creek, to within half a mile of the deposit on the
west and south. The deposit is referred to in the litera-
ture as the McPhail or Archer Lime Company deposit
of sec. 13 but has never been described in detail.
References: Bradley and Logan, 1919, p. 640; Laizure, 926, p. 237; Averill,
1947, p. 52; Logan, 1947, p. 276; Bowen and Gray, 1959, p. 38.
Melendy Ranch (Willow Creek) deposit. Loca-
tion: S'/2 sec. 21, NE% sec. 28 and W'/2 sec. 27, T. 15 S.,
R. 7 E., M.D., 20 miles southeast of Hollister; San
Benito 15-minute quadrangle. Ownership: George
Melendy Ranch and others (1947).
Crystalline limestone of the Sur Series lies along the
San Andreas fault zone as a series of broken masses
and slivers which constitute the Melendy Ranch
deposit. These masses cover an area l'/2 miles long by
a maximum of 500 feet wide and extend southeast of
the highway bridge in sec. 21. Most of the limestone
is blue gray to white, somewhat siliceous, and strongly
brecciated — the breccia fragments ranging in length
from a few inches to 50 feet or more. The breccia is
partly cement with calcite, but many of the fractures
are filled with "mountain leather" (matted, fibrous
asbestos) and other impurities. Noncarbonate meta-
morphic and sedimentary rocks are intermixed to
varying degrees with the limestone blocks and masses,
rendering most of the deposit impure. A composite
sample of limestone collected across a width of 75 feet
near the south end of the deposit by Logan (1947, p.
275) and analyzed by Abbott A. Hanks, Inc., showed
92.08% CaCO,, 2.99% MgCO,, and 4.59% Si02.
Although total reserves are probably fairly large,
most of the limestone is too intermingled with other
rocks to be extracted without extensive selective min-
ing and beneficiation. Relatively pure limestone ap-
pears to be available only in blocks and small masses.
There had been no work done on the property as of
66
California Division of Mines and Geology
Bull. 197
October 1962, and the limestone probably is only of
local interest.
Other references: Wilson, 1943, p. 193, plote 3; Bowen and Gray, 1959,
p. 39.
Middle Dam deposit. Location: N'/ sec. 29
(proj.),T. 13 S., R. 5 E., M. D., 5 to 5'/2 miles southwest
of Hollister; Hollister 15-minute quadrangle. Owner-
ship: Howard Harris, 7800 Cienega Road, Hollister
(1964).
This deposit consists of mixed carbonate rock ex-
posed discontinuously for about a mile along the
north wall of North Canyon. Much of the rock is
white, very coarse-crystalline limestone and dolomitic
limestone. It occurs as thin, steeply dipping, discon-
tinuous lenses interbedded with schist and commonly
cut by granitic dikes. One of the largest lenses, at the
east end of the deposit, is reported to be an average of
30 feet thick by 300 feet long (Oliver E. Bowen, 1964,
personal communication). Analyses of three samples
collected by Bowen and Harris are given below. The
first one (GP-24) was analyzed by Abbot A. Hanks,
Incorporated, in 1954 (Bowen and Gray, 1959, p. 32).
The others were analyzed by the Division of Mines
and Geology laboratory in 1964.
Ign.
Sample SiO, Fe,Q, AW, CaO MgO P.O, K.O loss
GP-24.... 0.52% 0.08% 0.16% 43.17% 10.32% tr n.d n.d.
MD-1 1.60 0.06 0.00 54.00 0.61 0.04% 0.00% 42.6%
MD-2 5.40 0.58 0.90 42.80 11.10 1.00 0.10 36.8
Carbonate rocks of the Middle Dam deposit appear
to be of mixed chemistry and limited reserves. Howev-
er, some of the material may be of economic interest
because of its whiteness and proximity to market.
Other reference: Taliaferro, 1948, map.
Mount Harlan deposit. Location: Sec. 22, T. 14 S.,
R. 5 E., M.D., 11 miles south of Hollister; Gonzales
15-minute quadrangle. Ownership: Not determined.
This deposit is referred to as the Hamilton deposit by
Bowen and Gray (1959, p. 38), apparently based on
interpretable data presented by Logan (1947, p. 275).
However, the location of the Hamilton deposit is
shown by Averill ( 1947, p. 51-52) to be near the lime
kiln in sec. 23 and is described that way herein.
Data from U.S. Steel Corporation (in Jennings and
Strand, 1958) indicates that a northwest-trending, len-
ticular mass of crystalline limestone caps the 3,262-
foot-high Mount Harlan. The mass is shown to be
4,000 by 1,200 feet in maximum dimensions and is
bordered by granitic rocks. An average of 33 analyses
of samples collected by U.S. Steel at 5-foot intervals
across the strike of the main part of the mass is report-
ed to be 52.22% CaO, 2.60% MgO, 0.75% Si02, and
0.64% AlzO, and Fe20, (Bowen and Gray, 1959, p.
38). The indicated size and quality of the deposit
would seem to warrant further examination. Howev-
er, no limestone was observed during aerial reconnais-
sance of the Mount Harlan area (Oliver E. Bowen,
1967, oral communication). The mountain is accessi-
ble from the south via an unimproved dirt road and
trail from Thompson Valley.
Natividad (Kaiser) deposit. Location: NW1/ sec.
1 and NE'/4 sec. 2, T. 14 S., and SE'/4 sec. 35 and SW'/4
sec. 36, T. 13 S., R. 3 E., M.D. (proj.), 6 miles northeast
of Salinas and 1 mile north of Natividad; Salinas and
San Juan Bautista 1 5-minute quadrangles. Ownership:
Kaiser Aluminum and Chemical Corporation, 300
Lakeside Drive, Oakland (1963).
Early development of the Natividad deposit is not
clearly recorded in the literature, but it is probable
that some of the small dolomite producers listed by
Laizure (1925, p. 36) obtained dolomite here intermit-
tently from 1900 to 1925. By 1926, Pacific Coast Steel
Company (succeeded by Bethlehem Steel Company
in 1937) began quarrying dolomite for use as a refrac-
tory near the north end of the Natividad pendant,
near SE cor. sec. 35. The operation was more or less
continuous until 1944, when the company ceased pro-
duction. In 1942, Kaiser Aluminum and Chemical
Corporation (then known as Permanente Metals Cor-
poration) opened a dolomite quarry and processing
plant half a mile to the south in the same deposit. This
plant supplied calcined dolomite which was reacted
with seawater at Moss Landing in order to produce
magnesia. Magnesia was used for making magnesium
metal at their Permanente plant in Santa Clara
County until 1945. Calcined dolomite also was
shipped directly to a company plant in Manteca, San
Joaquin County, for the manufacture of magnesium
metal between 1942 and 1944.
The demand for metallic magnesium was greatly
reduced by 1945, thereby critically decreasing the
need for Natividad dolomite. To offset the decrease, a
refractory brick plant was constructed next to the
Moss Landing seawater magnesia facility. This per-
mitted the company to utilize large amounts of mag-
nesia (and dolomite) and at the same time to provide
industry with a wide variety of refractory products.
Another operational change was made at the Nativi-
dad plant in 1952 when a heavy-media separation unit
was installed to beneficiate the dolomite. In addition,
the Moss Landing facilities have been expanded sev-
eral times.
The Natividad deposit is a large irregular pendant
of crystalline dolomite within the Santa Lucia Gran-
ite. The pendant is exposed over nearly three-quarters
of a square mile of area (plate 2) and about 700 feet of
relief (Allen, 1946, plate 1). The internal geology of
the mass is complex, the dolomite body having been
penetrated by numerous irregular dikes and sills of
granitic rock that is now largely decomposed. Addi-
tional fracturing and shearing has made it virtually
impossible to selectively quarry high-grade dolomite
on a large scale. The composition of the dolomite is
1978
LlMKS TON1' IN I III C.OASI R \\(;KS
67
Photo 13. High-ongle oblique oeriol view to east of Natividad dolomite quarry and plant in Monterey County, 1968. Crystalline dolomite of the Sur Series
is obtained from multi-level quorry (top, center) , crushed, washed, screened, and beneficiated by heavy-media separation (center} and finally crushed, screened,
and calcined at processing plant (bottom) . Dolomite quarry is largest in California. Photo courtesy of Kaiser Refractories.
further complicated by silica and silicate minerals im-
placed along shear planes and adjacent to dikes. Where
free from granitic and silicic impurities, the rock is
uniformly white, medium- to coarse-crystalline, rela-
tively pure dolomite. The company provided the fol-
lowing typical analyses for dolomite produced in 1962:
31.75% CaO, 20.30% MgO, 1.31% Si02, 0.20% Fe20„
0.35% A120„ and 46.09% COz. Except for the subordi-
nate production of exceptionally white material for
roofing and landscaping granules, none of the dolo-
mite is selectively quarried. A relatively high-quality,
uniform product is maintained, however, by heavy-
media separation and other practices. It is estimated
that approximately half of the mined material is wast-
ed.
Kaiser Aluminum and Chemical Corporation has
developed the Natividad quarry by two adjacent series
of benches (levels) cut into the western side of the
hill. In the northern quarry area, the 700- and 775-foot
levels are the most active. The 850-foot bench was
nearly worked out, and the 625-foot bench was inac-
tive when the quarry was last examined in September
1963. In the south part of the quarry, the 750- and
825-foot levels are worked to some extent, the others
being inactive. The highest level at 900 feet was
worked out. It was estimated that work on the lower
quarry levels would have to be resumed around 1970
at the 1963 rate of production.
Benching is conducted at 75-foot intervals in each
quarry area. The faces are blasted using ammonium
nitrate in 9-inch diameter holes drilled vertically by
rotary methods to 85 feet. Generally, a total of 30 to
40 holes are drilled on 25-foot centers and arranged in
three parallel rows for each blast. Each blast common-
ly yields a 2- to 3-month supply of rock. Some second-
ary blasting is necessary to reduce the larger blocks.
68
California Division of Minf.s and Geology
Bull 197
Photo 14. Natividad dolomite processing plant situated at base of hill below quarry (out of picture, top left) . Washing, screening and heavy-media separation
section located upper left. Beneficiated dolomite is stockpiled below (lower left) for final crushing, screening and calcining (center) . Photo courtesy of Kaiser
Refractories.
The rock is loaded by two 4'/2-cubic-yard capacity,
electrically powered shovels into large-capacity dump
trucks which haul a short distance to the large pri-
mary crusher located at the 700-foot level. Much of the
decomposed granitic rock is wasted as the rock is fed
over a grizzly to the jaw crusher. The material is
crushed to about minus 4 inches then passed over a
half-inch mesh screen where the fines, including some
granitic material, are wasted. The coarse rock is next
conveyed to a stockpile at the washing heavy-media
separation sections located about 250 feet lower in
elevation.
At the washing section, the dolomite is scrubbed in
a Hardinge mill and passed through an attached trom-
mel screen, both of which are supplied with fresh
wash-water. Rock larger than 3'/4 inches is sent to a
secondary jaw crusher and recycled to the scrubber.
The minus fraction is washed over a '/g-inch mesh
screen, the fines going to a thickener and then to a
waste pile. The plus %-inch dolomite is next conveved
to the heavy-media separation section for additional
beneficiation. At this point, virtually all of the decom-
posed granite and other "soft" impurities have been
removed from the rock.
The heavy-media separation (H.M.S.) section was
added to the processing plant in 1952 to remove the
harder, siliceous and granitic impurities so that a high-
quality dolomite product could be obtained. This
H.M.S. process has been described in detail by Len-
hart (1953, p. 89-93), Utley (1952, p. 94-96), and oth-
ers. The heavy medium is a suspension of finely
divided ferrosilicon and magnetite in water which is
kept at a specific gravity of 2.7. Impurities lighter than
2.7 are floated off and join the sludge from the thicken-
er and are wasted (the lightweight impurities actually
appear to be very sound and probably would be useful
as aggregate for structural purposes) . The heavier and
purer dolomite fragments (maximum specific gravity
— 2.85) sink in the heavy medium and are removed
from the H.M.S. cone by an air lift. Next, the heavy
fraction is washed over a screen and conveyed to the
stockpile at the calcining plant below. The ferrosili-
con and magnetite are reclaimed from the heavy me-
dium by a sequence of steps including magnetizing,
thickening, magnetic separation, and demagnetizing.
At the calcining plant, the dolomite is crushed and
screened to '/2- by '/-inch and minus '/,-inch sizes for
calcining in one of three gas-fired rotary kilns. Two of
the kilns are used to make caustic calcined dolomite;
the third, to make deadburned dolomite. Most of the
calcined dolomite is shipped in 25-ton trucks to the
company's seawater magnesia plant at Moss Landing.
1978
Limi sionk in nil Coast Ram.i s
69
The rest of the calcined dolomite, some of which is
hydrated, is used extensively in several forms by the
chemical, building, and agricultural industries.
Deadburned dolomite is produced by adding iron in
the form of mill scale to the dolomite feed and burning
at temperatures as high as 3,300° F. This product is
shipped in bulk or bags for use as a fettling material
in electric and open hearth steel furnaces.
Dolomite for roofing and landscape uses is selective-
ly quarried and processed separately in order to obtain
a uniformly white material. Crushed dolomite also is
sold to the steel industry for use in maintaining open-
hearth furnaces. In addition, dolomite fines from the
crushing plant are used for marking athletic fields and
for soil conditioning. Some of the waste material is
sold for use in road construction, and a small sand
plant was recently installed to process the waste fines.
Production of dolomite (excluding waste rock) at
Natividad during the last decade has been between a
quarter- and a half-million tons annually. Total pro-
duction through 1968 is estimated to be approximately
8'/2 million tons. Reserve figures are not available, but
based on the areal size of the deposit, dolomite re-
serves (including waste rock) may be on the order of
1 million tons per foot of depth.
Other references: Allen, 1946, p. 68-72; Logon, 1947, p. 197, 256-257;
Bowen and Gray, 1959, p. 25; Hort, 1966b, p. 55-59.
Palmtag-IIarris deposits. Location: SE1/ sec. 35,
SVV'/4 sec. 36, T. 13 S., R. 5 E., and NW'/4 sec. 1, T. 14
S., R. 5 E., M.D., 6'/2 miles south of Hollister and
immediately southwest of Cienega Road; Hollister 15-
minute quadrangle. Ownership: Howard Harris, 7800
Cienega Road, Hollister, owns the old Leopold Palm-
tag property (1962).
The Palmtag-Harris deposits are situated on the
north and east sides of a 1,612-foot ridge partly defined
by Bonanza Gulch on the west and the San Andreas
fault zone on the northeast. The deposits include two
moderate-size masses (Vineyard School, Hightop)
and several smaller ones (including Hayfield) as in-
dicated on plate 2. However, soil, caliche, and vegeta-
tion effectively mask the deposits, except at the west
end of the Vineyard School mass. Crystalline lime-
stone and subordinate dolomite constitute the depos-
its, which appear to be pendants in granodiorite.
Granitic dikes also cut the deposits in many places.
Brecciation and mixing of different rock types is com-
mon, the intensity increasing toward the San Andreas
fault zone. The limestone is blue gray to off white,
medium to coarse crystalline, faintly banded or brec-
ciated, and sometimes siliceous. Some off-white, me-
dium-crystalline dolomite was noted, particularly
along the ridge crest southeast of the 1,612-foot hill,
and may be present elsewhere. The chemistry of the
limestone is suggested by the analyses shown in table
14. The analyses shown by Bowen and Gray ( 1959, p.
36) for the Palmtag-Harris deposits are actually from
a deposit a mile to the northwest in NW1/, sec. 34
(proj.) (Oliver E. Bowen, 1963, personal communica-
tion).
Limestone reserves probably amount to several mil-
lion tons. However, considering the variable quality
of the limestone, its main use would appear to be for
cement manufacture. Even so, some selective mining
would be necessary to avoid dolomitic zones and ex-
cessive siliceous or granitic material. The main advan-
tages of the limestone are that it is easily accessible and
close to other limestone deposits. Also, it is only 10 or
11 miles by road southeast of the cement plant near
San Juan Bautista. According to Laizure (1926, p.
234), some dolomite was quarried on the Palmtag
Ranch long ago, but the location of the quarry is not
known.
The three deposit areas prospected and sampled in
recent years, mostly by the owner, are described in
additional detail below.
Vineyard School deposit. This deposit is located
a quarter of a mile southwest of Vineyard School at
the northwest end of the ridge. It covers an east-trend-
ing, teardrop-shaped area with maximum dimensions
of 1,000 feet by 600 feet and a relief of about 200 feet.
The limestone is blue gray to white, medium to coarse
crystalline, and brecciated. No dolomite was ob-
served, but granitic salients commonly cut the deposit.
The only surface samples analyzed were obtained
from a bold ledge at the west end of the deposit. These
analyses (F-H-l to 10, table 14) show the ledge to be
of relatively good quality. However, lower quality
limestone and the presence of numerous granitic dikes
are indicated in prospect cuts and drill holes made in
the 1950s by U.S. Steel Company. As drill data show
the deposit to extend to a depth of at least 180 feet,
limestone reserves, including granitic intrusives, are
estimated to be about 3 million tons.
Hightop deposit. The deposit is located high on
the northeast side of the main ridge 2,000 feet south of
Vineyard School. Although exposures are poor, pros-
pect cuts reveal the presence of carbonate rock over a
west-northwest-trending area about 1,600 feet long by
a maximum of 300 feet wide. Granitic rock also is
exposed in the cuts, and the deposit may consist of
several small masses. Most of the limestone is off white
to blue gray, medium to coarse crystalline, and faintly
banded. Some crystalline dolomite is present along the
southwest margin of the deposit, as well as farther
southeast along the ridge crest where no limestone
was observed. Analyses of 14 samples (see HT sam-
ples, table 14) indicate the limestone to be siliceous
and otherwise impure. The dolomite was not sampled
for analysis. More work is needed to determine the
quality and size of the deposit.
Hayfield prospect. Small broken masses of lime-
stone lie in an area of low relief in the San Andreas
fault zone a third of a mile southeast of Vineyard
School. These are poorly exposed but have been pros-
70
California Division of Mines and Geology
Bull 197
Table 14. Chemical Analysis of Palmtag — Harris Deposits, San Benito County
Sample
Fe
Si02
M2O3
ao
MgO
5
Mn
R&3
Loss
VINEYARD SCHOOL DEPOSIT *
F-H-l ....
F-H-2...
F-H-3...
F-H-4 ....
F-H-5 ....
F-H-6...
F-H-7...
F-H-8....
F-H-9...
F-H-10
0.17%
2.40%
0.40%
53.61%
0.72%
0.010%
0.030%
0.01%
0.64%
42.63%
0.35
2.18
0.40
52.60
0.71
0.007
0.030
0.01
0.90
43.40
0.40
2.80
043
52.40
0.72
0.007
0.040
0.02
1.00
41.90
0.20
1.70
0.11
54.20
0.47
0.006
0.050
0.01
0.40
43.40
0 30
1.80
0.27
54.00
0.80
0.007
0.030
0.01
0.70
43.12
0.20
2.00
0.30
54.60
0.84
0.010
0.040
0.01
0.56
42.10
0.10
0.60
0.16
53.90
1.36
0.007
0.030
0.01
0.30
43.25
0.15
2.80
0.19
51.80
1.80
0.010
0.020
0.01
0.40
43.40
0.10
1.06
0.16
52.90
0.86
0.007
0.027
0.01
0.30
45.20
0.20
0.70
0.12
54.50
1.11
0.007
0.012
0.01
0.40
44.00
HAYFIELD DEPOSIT *
FesOi &
Simple SiQ2 AlsQ3 CaO MgO
HF 1 4.67% 0.70% 53.70% 0.34%
HF 2 2.28 1.00 51.25 1.20
HF 3 2.81 0.47 51.50 0.31
HF 4 2.00 0.47 54.55 0.32
HF 5 0.92 0.14 55.45 0.30
HF 6 1.38 0.21 55.00 0.28
HFA 1 3.80 1.30 48.16 3.70
HFA 2 1.10 0.60 54.44 0.50
HFA 3 1.30 0.40 54.78 0.40
HFA 4 0.60 0.30 54.00 0.90
HFA 5 2.70 1.20 52.86 0.50
HFA 6 1.80 0.80 53.48 0.36
HFA 7 1.00 0.50 54.54 0.30
HFA 8 2.30 1.10 49.23 3.00
HFA 9 2.30 0.90 53.45 0.36
HFA 10 2.50 0.80 53.74 0.30
HIGHTOP DEPOSIT **
HT 1 16.62 3.60 43.50 0.21
HT 2 10.15 1.50 48.60 0.34
HT 3 7.25 2.00 49.30 0.46
HT 4 22.55 3.20 41.00 0.19
HT 5 18.25 4.00 42.15 0.93
HT 6 10.80 2.55 47.55 0.61
HT 7 11.25 2 30 47.50 0 54
HT 8 8.60 1.65 55.75 0 37
HT 9 4.50 1.10 51.30 1 26
HT 10 17.00 2.63 44.40 0.61
HT 11 32.20 5.01 33.50 0.68
HT 12 16.25 4.20 42.80 0.79
HT 13 14.25 3.70 45.15 0.47
HT 14 14.95 3.15 45.10 0.57
• Samples collected from resistant ledge al west end of deposit, analyzed by
U.S. Steel
• Samples collected from prospect cuts, analyzed by Howard Harris, owner.
pected by means of several cuts and are shown to be
500 feet long and less than 100 feet wide. The lime-
stone is typically blue gray, medium to coarse crystal-
line, and highly brecciated. Analyses of 16 chip sam-
ples (HF and HFA series in table 14), taken at 50-foot
intervals along the strike of the prospect, show the
limestone to be of general good quality. The prospect
appears to be too small to be of significant economic
interest.
Other reference: Bradley and Logan, 1919, p. 635.
Porter deposit. Location: \N'/2 sec. 7, T. 14 S., R. 4
E. (proj.), M.D., I1/ miles east of Natividad; Salinas
15-minute quadrangle. Ownership: James Porter, 701
Old Stage Road, Salinas (1959).
An undeveloped dolomite deposit l1/, miles east of
Natividad was described by Bowen and Gray (1959,
p. 28) as roughly 300 feet wide and 3,000 feet long,
with an eastward elongation and nearly vertical dip.
Granitic intrusions penetrate the mass in many places.
Most of the rock is white, medium-crystalline dolo-
mite similar to that in the Natividad (Kaiser) depos-
its. Three channel samples cut perpendicular to the
strike probably reflect the chemistry of the deposit.
ft
f
SiOn
•}
A/J>3
%
00
%
MgO
%
S
•r
p
%
Mn
%
'T-
(l>,.\
Hfi
%
0 10
1.52
0,38
41.20
1120
0004
0.010
11 (if,
IS
4S64
040
068
ait
33.00
20.67
0.00)
0.008
0.05
0.90
4510
0.20
0.84
Oil
32.00
20.35
0.001
0.006
0.05
0.50
46.5!
T he deposit was later mapped in detail by Bowen
(1968, unpublished map) and shown to consist of
mixed dolomite and limestone. Bowen also mapped
three other fairly large bodies of mixed limestone and
dolomite within half a mile to the north and west (see
plate 2).
Power Line deposits. Location: SW'X sec. 4, SE'/4
sec. 5, E'/2 sec. 7, and sec. 8, T. 14 S., R. 5 E. (proj.),
7'/2 to 9 miles south-southwest of Hollister; Gonzales
1 5-minute quadrangle. Ownership: Dr. Rollin Reeves,
Salinas (part of mineral rights to Ideal Cement Com-
pany?) (1964).
The Power Line deposits, referred to by Bowen and
Gray (1959, p. 32), extend southwest from SW'X sec.
4 to E'/2 sec. 7. They were named for the power line
that crosses the northern portion of the deposit group.
The deposits are situated on the ridges and rolling
upland surfaces that divide the three drainages of Pes-
cadero, Bird, and Swamp Creeks. Brief examination of
the deposits by Bowen and Hart in February 1964
indicated that none of the carbonate masses are large
and that some of the limestone is impure. T he largest
mass seen was about 1,000 feet by 700 feet in plan and
was exposed over 200 feet in relief. Much of the lime-
1'>-S
LIMESTONE IN THE (-OAS I RANGES
71
stone is medium to coarse crystalline and light blue
gray, but some is locally siliceous and dolomitic. The
great majority of carbonate bodies in the northeastern
two-thirds of the group are small and scattered (the
southwestern end of the Power Line group was not
examined). Although limestone reserves may amount
to several million tons or more, the deposits have not
been sampled or carefully examined, and little can be
said of the chemistry of the deposits.
Quail Creek deposit. Location: N '/2 sec. 7, T. 1 5 S.,
R. 5 E., M.D., 6 miles northeast of Chualar; Gonzales
15-minute quadrangle. Ownership: Hazel Hurt, Sali-
nas (1960).
At the west end of the Quail Creek deposit, adjacent
to (^uail Creek, a series of small quarries was worked
as a source of limestone for lime in the early 1900s. It
is quite possible that these quarries were operated by
J. C. Jens, who reportedly produced limestone from
near Chualar from 1910 to 1913 (unpublished
records), or by Spreckels Sugar Company, which op-
erated in the vicinity prior to 1910 (Laizure, 1925, p.
43). Apparently, the deposit then lay idle until 1959,
when Barnes Construction Company of San Marino
developed a large quarry on the south slope of the
ridge just east of the first development. In April I960,
this operation was inactive, although stockpiles and
equipment remained at the quarry (Hart, 1966b, p.
60).
This deposit consists of several narrow lenses or
beds of carbonate rock that extend nearly a mile east-
ward from Quail Creek and dip 30° to 50° S. The beds
are interleaved locally with schist, and the whole has
been penetrated by granitic dikes and sills. The main
lens attains an estimated maximum thickness of 150
feet, including schist and granitic salients, but is much
thinner at its extremities. Because the carbonate beds
dip more or less parallel to the southwest slope of the
ridge, the deposit appears to be much larger than it
actually is. It consists of nearly white, fine- and coarse-
crystalline calcite and medium-crvstalline dolomite,
which occur together in varying proportions to form
limestone, dolomitic limestone, and dolomite. Accord-
ing to Bowen and Gray (1959, p. 37), the western
third of the deposit consists of mixed carbonate rock
but the eastern two-thirds appears to be mainly lime-
stone.
Barnes Construction Company first developed the
deposit in early 1959 by stripping the soil and caliche
cover and by trenching and drilling, reportedly block-
ing out 2 million tons of rock. This was followed by
quarrying later in 1959 and possibly in early 1960. The
quarry, which is more than 1,000 feet long and has an
estimated maximum relief of 150 feet, is located in the
western half of the deposit. The face, which probably
slopes an average of 40°, is irregularly benched. By
means of cut and fill, the quarry floor has been extend-
ed 200 to 300 feet out from the toe of the face. Al-
though the quarry was not active when visited in
April 1960, the limestone apparently had been quar-
ried somewhat selectively and transported to a bench
about 20 feet above the quarry floor. By passing the
broken rock over a grizzly or grate on an inclined
chute from the bench to the quarry floor, some of the
decomposed granitic and other deleterious fines were
removed. The material was subsequently crushed and
screened with portable equipment, stored in open
piles, and sacked for shipment. In April 1960, there
were six conical piles of crushed rock ranging from 10
to 20 feet high and containing rock ranging from plus
6-inch to minus '/£-inch fines. In addition, several thou-
sand sacks of roofing granules (% by % inch) and
landscape rock (X by % inch) were stacked on pallets,
and several pieces of portable equipment (scraper,
loader, fork-lift, conveyor, and sacking machine) re-
mained at the quarry.
Based on observations at the quarry, production
would appear to be fairly large. However, much of the
material apparently was used to construct a road to
the quarry. Unpublished records show that only a
modest amount of carbonate rock was sold for land-
scape and roofing purposes.
Reserves of the Quail Creek deposit are difficult to
estimate because the dimensions of the carbonate bod-
ies are not sufficiently known. Perhaps several million
tons of carbonate rock could be quarried here; but the
proportion, quantity, and quality of limestone and
dolomite available are undetermined. A chemical anal-
ysis of a grab sample taken from one of the stockpiles
suggests that dolomite predominates in the quarry
area. The analysis, made by Lydia Lofgren of the Divi-
sion of Mines and Geology in 1962, showed 17% MgO,
36.25% CaO, 2.4% Fe20,", and 0.42% Si02. Although
heterogeneous in composition and color (some iron-
staining), most of the carbonate rock is physically
sound and probably suited to various construction,
roofing, and landscaping uses.
Reeves Northeast deposits. Location: Sec. 4, T. 14
S., R. 5 E., M.D., 772 miles south of Hollister; Gonzales
1 5-minute quadrangle. Ownership: Dr. Rollin Reeves,
Salinas (1964).
A number of small to medium-sized masses of lime-
stone and dolomite lie along the northeast-trending
ridge in the east or northeast part of the Reeves Ranch.
Two of the better quality limestone deposits lie at the
ridge crest close to the corner common to the Martin,
Kaiser-Harris, and McCray (Reeves) properties. The
largest and most northeasterly deposit, which lies
partly on the Martin and McCray Ranches, is roughly
1200 feet long by 700 feet wide. It consists of blue-
gray, medium-crystalline, banded limestone that
weathers into platy fragments. An analysis of a typical
sample showed 52.67% CaO, 1.41% MgO, 1.56% Si02,
0.17% Fe20„ 0.95% Al20„ and 0.03% P20, (Bowen
and Gray, 1959, p. 36).
Judging from the outcrops, the deposit appears to be
gently dipping and probably contains less than 1 mil-
72
California Division of Mines and Geology
Bull. 197
lion tons of limestone. A similar but smaller deposit
caps the knoll a few hundred feet to the southwest.
Other small limestone deposits are scattered through
the area but are locally dolomitic and siliceous and
commonly interleaved with granite and schist.
The only dolomite body of note is an arcuate lens
situated just west of the center of sec. 4 (proj.). It
crosses a saddle in the main ridge and extends at least
1,000 feet to the north into NW1/ sec. 4. The average
thickness may be SO to 100 feet. At one point, the body
consists of white coarse-crystalline dolomite, but it is
not known if dolomite is the predominant carbonate.
Reserves are undetermined and none of the above-
mentioned deposits is developed.
Sugarloaf deposits. Location: NW'/4 sec. 36 and
S'/2 sec. 25, T. 13 S., R. 3 E. (proj.), M.D., 7 miles
northeast of Salinas; San Juan Bautista and Salinas
15-minute quadrangles. Ownership: Not determined.
Bowen and Gray (1959, p. 28) have described the
deposit on Sugarloaf Peak:
"A broad belt of carbonate rock 600 to 700 feet wide and over
a mile long crosses Sugarloaf Peak, in a northeasterly direction.
The southwest third of the mass is mainly dolomite but toward the
northeast this grades into mixed dolomite-calcite rock. Northeast
of the crest of the peak the mass is poorly exposed because of thick
brush and soil mantle. Thus far, there has been no commercial
utilization of the Sugarloaf Peak rocks.
"The dolomite is grayish-white, mottled with small spots and
clots of red iron oxide. Veinlets of iron oxide and ferruginous silica
cut the mass in numerous places. Where the carbonate mass is
poorly exposed east of the peak, float consists of medium-grained
and coarse-grained, blue-gray to white dolomitic limestone and
finer-grained off-white dolomite.
"Because of the impure nature of the dolomite on the southwest
slope of Sugarloaf Peak and because of the apparent mixture of
calcite and dolomite rock east of the peak, it is doubtful if satisfac-
tory commercial deposits can be developed in this vicinity."
Another broad northeasterly-trending belt of car-
bonate rock is shown by Allen (1946, plate 1) in sec.
36, a short distance southeast of the Sugarloaf Peak
belt. Nothing is known about the quality of limestone
or dolomite in this large mass, but Allen (1946, p. 67,
72, and plate 2) states that limestone was obtained
from a quarry at the top of the hill half a mile south
of Sugarloaf Peak. This limestone was reportedly
burned in an old brick kiln located at the forks of
Gabilan Creek a mile northeast of Sugarloaf Peak.
Allen ( 1946, plate 1) shows several other large masses
of carbonate rock '/2 to 2 miles southeast of Sugarloaf
Peak but does not describe them or differentiate the
limestone and dolomite. On the basis of size alone,
these deposits would appear to warrant further exami-
nation and exploration to assess their economic value.
Underwood deposits. Location: Near center sec.
13 (proj.), T. 13 S., R. 4 E., M.D., 4'/2 miles southeast
of San Juan Bautista; Hollister 1 5-minute quadrangle.
Ownership: Ideal Cement Company, 420 Ideal Ce-
ment Building, Denver, Colorado 80202 (1959).
This deposit is described by Bowen and Gray ( 1959,
p. 25):
"The Underwood deposits are a series of small, discontinuous
masses of limestone located near the San Andreas fault zone close
to and on the northeast side of the San Juan Canyon Road half
a mile north of the Pearce-Twohy deposit. The Underwood prop-
erty is part of the former Cienego del Gabilan land grant. It was
operated for many years as a source of cement rock by the San
Juan Portland Cement Company. The limestone reserves have been
largely depleted and the quarries have been long idle.
"The limestone masses are within a triangular area bordered on
the north and east by faults and on the west by San Juan Valley
alluvium. The total reserves probably never exceeded a million
tons, and individual masses ranged from a few thousand tons to
several hundred thousand tons. The masses are in granite and
quartz-mica schist wall rocks. The rock is similar in character to that
of the Bryan and Pearce-Twohy deposits."
Other references: Bradley and Logan, 1919, p. 628; Logan, 1947, p. 276;
Taliaferro, 1948 (map).
Upper Bird Creek deposit. Location: NE1/ sec. 6
(projected), T. 14 S., R. 5 E., M.D., V/2 miles south-
west of Hollister; Hollister and Gonzales 15-minute
quadrangles. Ownership: Dr. Rollin Reeves, Salinas;
mineral rights probably held by Ideal Cement Com-
pany (1959).
This limestone deposit is described by Bowen and
Gray (1959, p. 32):
"In plan this deposit is shaped like a T-bone steak with the longest
axis trending northwest. It is about 1,600 feet long, 800 feet in
maximum width, and has been exposed to a depth of over 400 feet.
Most of the rock is medium-grained, blue-gray material suitable for
portland cement, but a dolomite streak crosses the northwest end of
the mass and the deposit would have to be thoroughly tested by
drilling to establish whether the mass as o whole is sufficiently low
in magnesium. Five to 10 million tons of limestone could probably be
developed in the Upper Bird Creek deposit. The following analyses
done by L.A. Caetano, courtesy Ideal Cement, on type samples col-
lected by Gray are representative of most of the deposit:"
Sam-
ple
SiOi
AW,
CaO
MgO
KnO
NajO
Ign
loss
G-16
0.38%
0.12%
0.18%
55.4%
0.35%
0.03%
0.10%
43.65%
G-17..
0.50
0.12
0.12
54.8
0.54
0.03
0.04
43.68
G-18..
0.88
0.08
0.10
50.2
4.38
0.03
0.05
44.18
G-19..
1.28
0.11
0.13
54.0
0.39
0.05
0.13
43.34
G-20..
0.98
0.15
0.17
54.2
0.35
0.05
0.05
43.26
There is no known development of the deposit.
Westphal Ranch deposit. Location: Sees. 10 and
11, T. 15 S., R. 5 E., M.D., on the south slope of Mt.
Olds, 8 miles northeast of Chualar; Gonzales 15-
minute quadrangle. Ownership: Herald Ranch (a
trust estate) , Herb G. Meyer, 145 Auburn Street, Sali-
nas (1959).
The general distribution of carbonate rock of the
Westphal Ranch deposit is shown in plate 2. The
deposit is described by Bowen and Gray (1959, p.
38-39):
"The beds are sinuous but have a general east strike and a steep
south dip. The carbonate rocks are interbedded with quartz-mica
schist and quartzite, and some skarn-rock has developed along
granitic contacts. None of the lenses exceed 200 feet in width and
they are scattered along more than a mile of strike length. The rock
1978
I.IMFSIOM l\ I III Co\si K \\<;i s
73
is medium- to coorse-crystalline and blue-gray to nearly white. The
chemical variations, based upon nearly 100 surface samples, are
indicated in the following table:
Ft Si02 MA 00 MgO S P Sin ftft H/)
. 1 5- iO .28-5.2 07-63 329-53.8 2.0-18.2 01-005 .001- 13 .02-06 if1)) 42-44
"Because of the heterogeneous noture of the deposit uniform rock
can only be obtained in masses containing less than 1,000,000 tons
each; many are much smaller than this."
Other carbonate deposits exist to the west in sec-
tions 9 and 10, but nothing is known of them. These
and the Westphal Ranch deposit are undeveloped.
Westvaco (Hollister; O'Hara Ranch) deposit. Lo-
cation: Sec. 2 (proj.), T. 15 S., R. 5 E., M.D., 7 miles
south of Hollister; Gonzales 15-minute quandrangle.
Ownership: Inorganic Chemicals Division, FMC Cor-
poration, P.O. Box 344, Newark (1963).
Crystalline dolomite, exposed on a low hill half a
mile south of the winery in Cienega Road, has been
quarried extensively since 1915. In that year, two com-
panies opened quarries within half a mile of one an-
other. San Benito Quarries Company (Baldi and
Rothschild) developed a quarry and adit near the top
of the hill on the O'l lara Ranch and produced modest
amounts of dolomite until 1926. About half a mile to
the west, on the property of San Benito Vineyards
Company, and near the center of sec. 20, A. A. Haskins
opened a hillside quarry which he apparently worked
in a limited way for a few years. From 1937 to 1946,
A. E. Hamilton produced an average of 7,000 or 8,000
tons of dolomite annually from the same area as Has-
kins. This part of the deposit may still be owned by
Mrs. A. E. Hamilton. Hamilton also had an option on
the O'Hara Ranch property, which he explored to
some extent.
In April 1944, Westvaco Chlorine Products Corpo-
ration (predecessor of present owner) acquired that
option and has produced substantial amounts of dolo-
mite every vear since 1947. Practically all of the dolo-
mite produced prior to 1947 was shipped to San
Francisco and Los Angeles for use as a refractory lin-
ing in open hearth steel furnaces. All of the dolomite
produced from 1947 to 1968 was shipped to the
owner's chemical plant in Newark where the
dolomite was calcined and reacted with salt water
bitterns to produce magnesium compounds. The
Newark plant ceased operation in August 1968. Quar-
ry operations were either stopped or greatly reduced
by the end of 1968, although some dolomite fines were
being sold for agricultural use and glass manufactur-
ing. Total production of dolomite from 1915 to 1968 is
estimated to be about 2'/2 million tons.
According to previous descriptions and unpub-
lished mapping, the Westvaco deposit apparently is
half a mile long but mav consist of several disconnect-
ed masses of dolomite mostly in SE'X sec. 2. The main
part of the deposit has been examined and described
by Bowen and Gray (1959, p. 37):
"White, medium crystalline dolomite occurs in a northwest-elon-
gated mass roughly oval in plan. The mass is ot least 1,800 feet
long and 600 feet wide and has been explored to a depth of nearly
200 feet. It is enveloped in deeply weathered schist and granitic
rock and granitic instrusions penetrate the dolomite in several
places. The deposit is in or close to the San Andreas fault zone and
the dolomite has been thoroughly crushed throughout the deposit.
This lowers the cost of quarrying but raises the proportion of waste
material. Several million tons of usable rock were proved. Further
exploration was being done during the summer of 1958. According
to the company the rock runs close to the theoretical composition
for dolomite — slightly over 21 percent MgO. Iron oxide stains
along the fracture surfaces are the only visible impurity. Logan
(1947, p. 278) lists an analysis made by Smith-Emery Company
from a sample collected toward the north end of the mass from a
quarry then operated by A. E. Hamilton, which is probably repre-
sentative of the deposit."
Si(h MaOj Fe^Oj CM MgO Mn CQ2
0.17% 0.36% 0.11% 31.00% 21.23% 0.006% 47.30%
Other references: Bradley and Logan, 1919, p. 633-635; Averill, 1947, p.
49-50.
PANOCHE HILLS DISTRICT (C-2)
Marly magnesian limestone is found as lake beds in
the Tulare Formation of Plio-Pleistocene age in sev-
eral places in the Panoche Hills, Fresno County (plate
lC). The carbonate rock, known as the Marlife depos-
it, was produced in the vicinity of sec. 18, T. 14 S., R.
11 E., between 1947 and 1953 for use in soil condition-
ing. The material is considered too impure to be of
value for most limestone or dolomite uses.
Marlife (Burkhart and Teaford) deposit. Loca-
tion: Sees. 17, 18, 19,20, 29, 30, T. 14 S., R. 11 E, M.D ,
2'/2 miles east of Mercy Hot Springs and 24 miles west
of Mendota; Panoche Valley 15-minute quadrangle.
Ownership: A. R. Burkhart and Otis Teaford (1951);
operated by Marlife Company, Fresno, J. H. McClo) .
Jr., President (1953).
The Marlife marl deposit was first developed in
1946 by A. R. Burkhart and Otis Teaford, who located
15 placer claims at the crest of the Panoche Hills.
Commercial development followed in 1947 when the
Marlife Company, apparently under a lease from the
owners, commenced production that continued at
least until 1953. There was a little production in 1955,
apparently all experimental.
The marl (impure limestone), exposed along the
crest of the Panoche Hills in sees. 17, 18, 19, 20, 29 and
30, occurs as a capping and as thin strata interbedded
with clay, silt, and sand of the flat-lying, nonmarine
Tulare Formation (Plio-Pleistocene). Some of the
limestone resembles caliche, but most of it was proba-
blv formed as lake beds. Where quarried at the hill
crest in sec. 18, the limy bed is estimated to be 3 to 5
feet thick and is covered by 1 to 4 feet of soil. The
limestone is nearly white to light buff, porous, soft to
moderately hard, and breaks or crumbles easily into
small fragments. As indicated by the analyses in table
1 5, the material is quite impure, being siliceous, alumi-
-4
California Division of Mines and Geology
Bull. 197
nous, and dolomitic. Similar limestone occurs to the
southeast in SE'/4 sec. 18 and NE% sec. 19, along the
crest of the Panoche Hills. Impure limestone and
other marly beds of the Tulare Formation also are
reported in Little Panoche Valley and elsewhere to
the north (Briggs, 1953, p. 48^49) and in N'/2 sec. 30
to the south (Anderson and Pack, 1915, p. 210). Analy-
ses of limestone from sec. 30 are given in table 15.
Table 15. Chemical analyses of limestone of the Tulare
Formation, Panoche Hills, Fresno County.
Samples from
Samples from
sec
18'
sec.
SO"
Oxide
Marlife 1
\ijrhu- :
#/
#2
Si02
12.30%
14.30%
19,84%
9.74%
ai2o3
8.20
5.30
4.97
2.76
Fe203
1.30
0.80
1.95
1.65
MgO
8.80
16.00
5.28
1.85
CaO
32.90
25.30
34.06
45.48
Na20
0.50
0.30
ND
ND
K20
0.30
0.20
ND
ND
p2o5
0.05
0.03
ND
ND
so3
ND
ND
none
none
Ignition loss
(C02+H20)
34.20
37.50
29.85
35.94
Total
98.55
99.73
95.95
97.42
ND= Not done
• Samples Marlife 1 and 2 were collected by Earl W. Hart and analyzed by
Lydia Lofgren, Division of Mines and Geology, March 1963. Marlife 1
is soft, crumbly, represents 2 feel of thickness near center 1K-14S-11E;
Marlife 2 is from moderately hard, thin ledge in N W'/4 18-14S-1 IE.
" Anderson and Pack {1915, p. 210) samples are from N1/, 30-14S-UE. Sam-
ple #1 is typical of marl bed 15-20 feet thick; #2 is from thin, hard
limestone bed (analyst, George Steiger).
Development of the Marlife deposit consists of sev-
eral shallow pits or broad trenches from which materi-
al was quarried in NW'/4 and center of sec. 18. A few
prospect pits and trenches are located within 2 miles
to the southeast along the crest of the hills. Quarrying
of the thin marl horizon and removal of overburden
were conducted using a tractor-powered carryall. The
marl was delivered to a nearby hammer mill, where it
was pulverized, and subsequently delivered to points
in the San Joaquin Valley for sale as agricultural lime-
stone (Logan, et al., 1951, p. 507-508). The production
pits have estimated maximum dimensions of 400 feet
long, 100 feet or more wide, and 5 to 10 feet deep. It
is estimated that roughly 30,000 to 40,000 tons of marl
and soil overburden were excavated. Probably over
half of this was processed as agricultural lime. Accord-
ing to the California Department of Agriculture (Spe-
cial Publications 231, 236, 239, 244, 247, 251), partial
analyses of the commercial marl varied from 33.75%
to 48.47% CaC03 during the 1948-1953 period. Appar-
ently some soil was admixed with the marl during
excavation, as these analyses are lower in equivalent
CaO than sample analyses shown in table 15. Future
value of the Marlife deposit and similar marl deposits
of Panoche Hills appears to be limited to agricultural
uses There is no record of commercial production
since about 1953.
NORTHERN SANTA LUCIA DISTRICT (C-3)
This district encompasses the northern half of the
Santa Lucia Range and the smaller Sierra de Salinas
to the northeast. It lies totally within Monterey
County (plate lC). Much of the northern Santa Lucia
Range district is rugged and rather remotely situated
with respect to major lines of transportation. The
northeast side of the district is served by a railroad and
highway along the Salinas Valley. The southwest side,
where most deposits are located, is served only by a
winding highway along the precipitous Pacific Coast.
The nearest major marketing center is the San Fran-
cisco Bay Area 100 to 150 miles to the north.
The oldest and most important carbonate deposits
are crystalline limestone and dolomite associated with
schist, gneiss, quartzite, and other metamorphic rocks
of the pre-Cretaceous Sur Series. This metamorphic
unit has been intruded by granitic rocks of probable
Late Cretaceous age. Upper Cretaceous, Tertiary, and
Quaternary sedimentary rocks flank and locally over-
lie the crystalline basement. Except for impure dolo-
mite of the Miocene Monterey Formation and an uni-
dentified shell deposit, none of the sedimentary rocks
has been of economic interest. No limestone or dolo-
mite deposits are known from the Francisca rocks
southwest of the Sur-Nacimiento fault zone. Uplift
and erosion in recent geologic time have exposed the
crystalline basement rocks over a broad region in the
northern part of the range. Faulting and folding have
severely deformed the range, and the older crystalline
rocks in particular are brecciated and sheared in many
places.
The great bulk of carbonate rock in the northern
Santa Lucia Range is confined to a 3-mile wide, north-
west-trending belt in the Coast Ridge area (Hart,
1966b, p. 61-62). The belt is more or less defined by
the Sur-McWay (Nacimiento) fault zone on the
southwest and the Palo-Colorado and Coast Ridge
faults on the northeast (Jennings and Strand, 1958).
Carbonate rocks also are found west of Junipero Serra
Peak and elsewhere in the range but in much smaller
concentrations. The general distribution and loca-
tions of the known carbonate deposits, based largely
on the work of Trask (1926), Reiche (1937), and
Fiedler (1944), are shown in figure 5. Most of the
deposits are much smaller than indicated and
generally consist of multiple small lenses and beds of
carbonate rock associated with various noncarbonate
rock.
Although a few deposits are relatively pure lime-
stone, most carbonate bodies are mixtures of lime-
stone and dolomite, the former predominating. Much
of the Sur Series limestone is white to light blue gray
and fine to very coarse crystalline, with local concen-
trations of graphite crystals 1 or 2 mm across. Near
intrusive contacts, the limestone shows development
of a wide variety of calcium and magnesium silicates.
Silica also is present as quartz. Dolomite occurs both
1978
I mom IN nil Co\Sl K s
75
R.2E
R 3E
EXPLANATION
Sur Series and intrusive
granitic rocks undivided
with crystalline limestone
and dolomite (shaded)
Other rocks (essentially
non-carbonate bearing)
15 miles
T20S
T2IS
T22S
T23S
R 5 E
R 7E
Figure 5. Mop showing distribution of Sur Series carbonate rocks, northern Santa Lucio Range.
6— 89454
76
California Division of Mines and Geology
Bull. 197
as an impurity interspersed with calcite and as rela-
tively pure bands and zones that replace the limestone.
The purer types of dolomite are fine to coarse crystal-
line, off white to gray and cream colored.
There have been no commercial developments of
carbonate rock for many years in the northern Santa
Lucia Range. Limestone at Bixby Creek and Limekiln
Creek (near Lucia) was burned for lime and exported
from Monterey County by ocean vessels prior to 1910.
Deposits at Tassajara Hot Springs, Lambert Ranch,
Limekiln Creek (near Chualar), and Jolon, however,
were developed only as small, local sources of lime
rock.
Pico Blanco is the outstanding deposit in the region,
containing immense reserves of limestone of adequate
quality to meet the specifications of cement and other
limestone uses. Deposits at Bixby Mountain and
Limekiln Creek (near Lucia) probably contain sub-
stantial limestone reserves, but the limestone is of
variable quality and is distributed among numerous
small to medium-sized bodies. The Horse Canyon
deposit also may contain substantial reserves, but re-
quires closer examination before it can be evaluated.
Smaller reserves of limestone, and possibly dolomite,
are available at other deposits. Future development of
the various deposits is hindered by poor accessibility
and distance from transportation and market facili-
ties. Additionally, some interests would no doubt op-
pose any mining operation that might impair the
recreational and wilderness values of the region.
Nonetheless, development of the Pico Blanco lime-
stone and possibly other deposits undoubtedly will be
desirable in the future.
The deposits are described alphabetically below.
Bixby Creek deposit. Location: N'/2 sec. 16 and S'/2
sec. 9, T. 18 S., R. 1. E., M.D., 16 miles south of Monte-
rey and 2 miles east of Bixby Landing; Point Sur 15-
minute quadrangle. Ownership: Not determined.
This deposit was worked from 1904 to 1910 by Mon-
terey Lime Company of San Francisco (Logan, 1947,
p. 259). During this period, an estimated 75,000 tons
of limestone were produced and calcined in three
large vertical wood-fired kilns situated on Bixby
Creek (Aubury, 1906, p. 73). The lime was hauled by
overhead tramway to Bixby Landing on the coast
where it was loaded onto ships waiting off shore.
There were no roads into the area at the time of devel-
opment, although a dirt road now extends to the
deposit from the coast.
Small detached masses of limestone centering near
N1/ cor. sec. 16 extend northwestward over a distance
of half a mile and constitute the Bixby (-reek deposit.
I he masses of limestone are locally brecciated and cut
by numerous salients of granitic rock. The limestone
mainly is white and coarse crystalline and often con-
tains concentrations of graphite crystals. Analyses of
three samples of the better quality limestone from the
quarry area (Hart, 1966b, p. 62) are given below (in
percent by weight):
Sample AO Fe.O, AW, OO JlgC) Ko,
LSL-5 3.84% 0.10% 0.18% 51.82% 1.04% 0.02%
LSL-6 1 82 0.08 0.38 52.80 1.22 0.03
LSL-7 1.96 0.12 0.30 52.93 1.06 0.03
Development of the deposit consists of a series of
small quarries or pits situated near N1/ cor. sec. 16
about 1,000 feet north of the lime kilns. Future devel-
opment of the Bixby Creek deposit is limited by its
small size and remote location.
Bixby Mountain deposits. Location: Mainly W'/2
sec. 14, sees. 15 and 23, and N'/2 sec. 25, T. 18 S., R. 1
E., M.D., 16 to 18 miles south of Monterey and 3 to 4
miles inland from the coast; Point Sur 15-minute
quadrangle. Ownership: Not determined.
The Bixby Mountain deposits comprise a group of
carbonate bodies that extend southeastward for a dis-
tance of 3 miles from Bixby Creek near the north
border of sec. 15 to Little Sur River in N'/2 sec. 25.
Situated in rugged, heavily vegetated terrain, the
deposits range in elevation from 800 feet at Bixby
Creek to 2,920 feet at Bixby Mountain. Trask ( 1926, p.
131, map) depicted the crystalline carbonate rocks as
northeast-dipping, elongated bodies lying at three or
four principal horizons within the Sur Series. The
largest body, located mostly in SW'X sec. 14, is indicat-
ed by Trask to cover an area 2,000 feet wide and more
than a mile long. Based on a partial, brief examination
of sec. 23 and 24 by Oliver E. Bowen (oral communi-
cation, 1961 and 1964), the carbonate bodies of Trask
are composite, consisting of smaller bodies of carbon-
ate rock associated with schist and other metamorphic
rocks of the Sur Series. Most of the deposits are mix-
tures of limestone and some dolomite and are com-
monly cut by fingers of granitic rock. The limestone
and dolomite are similar to other carbonate rocks in
the northern Santa Lucia Range, varying from white
to gray and from fine to very coarse crystalline.
Chemical analyses of typically white, medium- to
coarse-crystalline, good-quality limestone from the
main mass north of Bixby Mountain are given in per-
cent by weight by M. E. Maddock and C. C. Carlson
(1961, unpublished consulting report for O. P. Jen-
kins):
Simple SiO, Fe..O, AW, CaO MgO P:6~
B-l 1.32% 0.02% 0.78% 54.09% 0.54% 0.12%
B-2 1.04 0.03 0.53 54.19 0.68 0.09
It is possible that small to moderate-sized deposits of
limestone or dolomite of economic interest may exist
in the Bixby Mountain area, although insufficient
work has been done to delineate specific bodies.
However, preliminary examination does indicate no
large reserve at any one deposit. Future development
of the deposit will undoubtedly be hampered by the
remoteness and difficult access of the region.
Other reference: Hart, 1966b, p. 62-63.
1978
I.IMI SIONI l\ I III COASl K Wl.l S
77
Coast Ridge deposits (includes Marble Peak).
Location: T. 19 and 20 S., R. 2 E., T. 20 S., R. 3 E., and
T. 21 S., R. 3 and 4 E., M.D., 24 to 42 miles southeast
of Monterey; Lucia 15-minute quadrangle. Owner-
ship: Not determined, but partly Los Padres National
Forest (1960).
A large number of small to medium-sized bodies of
Sur Series carbonate rock occur discontinuously along
an 18-mile northwest-trending belt (figure 5). These
lie between the Coast Ridge fault and the McWay fault
and are described in a general way by Reiche ( 1937,
p. 123-126, 193, map). The deposits of the northwest
half of this belt, which are exposed intermittently
along the Coast Ridge road, were examined briefly in
1960 and found to be too small and impure to be of
economic interest (Hart, 1966b, p. 130-131). Most of
these carbonate bodies showed significant amounts of
silicate minerals due to contact metamorphism. The
deposits examined include some of the small un-
developed deposits reported in the vicinity of Marble
Peak (SW'/4 sec. 22, T. 20 S., R. 3 E.) by Logan (1947,
p. 259).
The deposits southeast of Marble Peak were not
visited.
Horse Canvon deposit. Location: S'/4 sec. 35, T. 19
S., R. 5 E., and N'/2 sec. 2 and NE'/4 sec. 3, T. 20 S., R.
5 E., M.D., 1 1 miles southwest of Greenfield; Junipero
Serra 15-minute quadrangle. Ownership: mainly Los
Padres National Forest (1968).
According to D. L. Durham (1968, personal com-
munication), pre- Tertiary crystalline limestone is
well exposed along Horse Canyon in sees. 35 and 3 and
on the high ridge to the east in sec. 2. The limestone
is associated with other metamorphic rocks of the Sur
Series that form a northwest-trending fault block
bounded by Miocene sandstone and calcareous shales
on the northeast and Eocene sandstone resting on pre-
Tertiary crystalline rocks (undifferentiated) on the
southwest. The limestone apparently crops out in an
elliptical area roughly a mile long by a third of a mile
wide and has a relief of about 1,200 feet on the ridge
east of Horse Canyon.
Just how much of the deposit area is underlain by
limestone, and the relationship of the limestone to
associated Sur Series rocks, remain to be determined.
Much of the limestone is reported to be white. A small
sample provided by Durham consists almost entirely
of coarse-crystalline calcite with scattered flakes of
graphite and small grains of iron ore (limonite?). It is
not known if the sample is representative of the depos-
it.
Preliminary data justify a closer look at this deposit
to determine its size, distribution, relationship to
other Sur Series rocks and possible granitic intrusives,
and chemical variations. Should a large limestone
deposit — or even modest reserves of high-quality lime-
stone— prove to exist, its economic value would be
enhanced by its relative accessibility to major trans-
portation lines and favorable topographic relief. Oliv-
er E. Bowen (personal communication, 1970)
estimates reserves of carbonate rock to be roughly 10
to 15 million tons.
Jolon deposit. Location: Not determined. Owner-
ship: Not determined.
A "shell deposit" a few miles south of Jolon, Monte1
rey County, reportedly supplied material for a lime-
kiln operated prior to 1893.
References- Preston, 1893, p. 260; Logon, 1947, p. 259.
Junipero Serra deposits. Location: Sec. 6, T. 21 S.,
R. 5 E., and sees. 13, 24, and 36, T. 20 S., R. 4 E.. M.D.,
19 to 20 miles west of King City; Junipero Serra 15-
minute quadrangle. Ownership: U.S. Government;
claimed by Sparks, Pearson, and Talcott in sec. 6 and
by Frank Watkins in SW'/4 sec. 36 (1958-1959).
A number of Sur Series carbonate bodies of unde-
termined size lie 3 to 5 miles from Junipero Serra Peak
within half a mile of Indians Road. They are situated
in rugged terrain that is accessible over many miles of
improved dirt and paved roads from King City and
Greenfield. The deposits are undeveloped except for
claim location work and minor sampling.
Perhaps the largest deposit lies in the SE1/ sec. 6 on
the Sparks, Pearson, and Talcott claims. Exposures of
limestone just north of Roosevelt Creek show the
deposit to be 150 to 200 feet thick and to dip steeply
into the hill. Exposures of carbonate rock can be
traced visually to the northwest along a common
trend, but it is not known if they represent a contigu-
ous deposit or multiple lenses. At the southeast end of
the trend, the deposit largely consists of very coarse-
crystalline, nearly white limestone containing local
concentrations of crystalline graphite and possibly
some silica (Hart, 1966b, p. 66). An analysis of SP-1,
a typical example, is given in table 16. Samples SP-2
and 3 are siliceous dolomite of the Miocene Monterey
Formation exposed southwest of the limestone in sec.
6.
A mile or more northwest of the above claims and
along the same deposit trend are the claims of Frank
Watkins in SW1/ sec. 36. Here, the carbonate rock is
impure and not well exposed. Chemical analysis of
two samples (Jun-1 and 2 in table 16) indicate the
material to be siliceous and strongly dolomitic. Five
other samples (Indians 1-5), taken from bodies 50 feet
thick or less, show that relatively pure limestone and
dolomite are present along Indians Road. Other car-
bonate bodies are indicated a short distance west of the
road by Reiche (1937, map), but have not been exam-
ined.
The carbonate deposits examined appear to be of
limited economic interest at the present time because
of their small size, variable quality, and remote loca-
tions with respect to markets. However, more work
needs to be done to evaluate the Junipero Serra depos-
its. The nearest rail facilities are 30 to 35 miles away
by road.
78
California Division of Mines and Geology
Bull 197
Toble 16. Chemical analyses of carbonate rock samples
from Junipero Serra deposits, Monterey County.
Ign
Simple
S1O2
FesOi
CiO
MgO
P2O5
loss
SP-1
1 .08%
0.16%
0.34%
; ! ;n'"(
1.12%
0.10%
ND
SP-2
24.00
1.00
0.44
23.12
15.52
0.05
ND
SP-3
9.32
0.30
0.43
29.06
17.91
0.18
ND
Jun-1
3.88
0.13
0.53
54.31
16.26
0.02
ND
Jun-2
7.70
0.17
1.62
37.77
10.10
7.11
ND
Indians 1
2.65
0.41
0.31
54.25
0.51
0.08
41.80%
Indians 2 ..
3.65
0.27
0.33
53.75
0.68
0.1
41.24
Indians .1 ..
0.61
0.14
0.08
55.00
0.51
0.08
43.44
Indians 4
1 64
0.04
0.08
52.75
2.04
0.1
42.60
Indians 5
0.13
0.07
0.04
33.25
19.50
0.02
46.72
N D. not done
SP samples collected in SE1/, 6-21S-5E b
v Oliver E. Bowen and Earl W Hart
July IS, 1957, and analyzed by Abbot A. Hanks, Inc., March 25, 1958. SP-1
is Sur Series crystalline limestone, SP-2 and -3 are pale brown, siliceous
dolomite of the Monterey Formation.
Jun samples collected in SW'/4 36-20S-5E by Frank Watkins in 1957 and
analyzed by Abbot A. Hanks, Inc., March 26, 1°58. Samples are from Sur
Series.
The Indians samples were collected by Oliver E. Bowen, April 30, 1959, and
analvzed by Lydia Lofgren of the Division of Mines and Geology, Octo-
ber 26, 1°62. The samples are from small lenses of Sur Series exposed
along Indian Road in SW'/4 sec. 13, NW1/, sec. 24, and SYV1/, sec. 36, T.
20 S., R. 5 E.
Lambert Ranch (Jamesburg) deposit. Location:
SW'/4 sec. 17, SE>/4 sec. 18, and NW'/4 sec. 20, T. 18 S.,
R. 4 E., 24 miles southeast of Monterey and l!/2 miles
southeast of Jamesburg; Jamesburg 15-minute quad-
rangle. Ownership: Not determined.
The deposit consists of several small limestone
lenses which were mapped by Fiedler (1944, p. 183,
plate 9) as a single lens half a mile long, trending N
20° W and centering just east of the SW cor. sec. 17.
The limestone is described by Oliver E. Bowen (Hart,
1966b, p. 66-67) as medium to coarse crystalline,
white to light blue gray, and cut by numerous fingers
of granitic rock. It is developed by two small quarries,
long abandoned. Because the deposit locally contains
silicate minerals and is small, it probably is not of
commercial interest. Bowen collected three samples of
limestone in 1954 and had them analyzed by Abbot A.
Hanks, Inc. The first two are from the north quarry
and the third from the south quarry.
Sample SiQ2 F<qP3 AJoOj CaO MgO PJ~
LSL-2 0.24% 0.09% 0.13% 54.38% 0.99% Tr
LSL-3 0.18 0.08 0.12 54.29 1.12 Tr
LSL-4 0 16 0.11 0.13 54.39 1.06 Tr
The limestone probably was quarried as a source of
lime, but there is no record of production.
Limekiln Creek deposit (near Chualar). Loca-
tion: E'/j sec. 28, T. 16 S., R. 4 E., M.D., 4 miles south
of Chualar; Salinas 15-minute quadrangle. Owner-
ship: Not determined.
Two small lenses of Sur Series limestone, located
just north of the canyon mouth of Limekiln Creek,
were developed by tiny quarries many years ago. The
rock was calcined for lime at a nearby kiln. The lime-
stone is white, medium to coarse crystalline, and local-
ly graphitic. The main or northeast lens is a little over
100 feet long and is a northwest-trending pendant in
granitic rock (Oliver E. Bowen, 1960, personal com-
munication). Two limestone samples, one from each
lens, were collected by Bowen and analyzed by Abbot
A. Hanks, Inc., in 1955 (Hart, 1966b, p. 67).
Simple SiOs FesOj M2O3 CaO MgO P2p7~
LSL-8 0.32% 0.09% 0.21% 53.53% 1.66% 0.03%
LSL-9 0 54 0.06 0.30 52.81 2.07 0.02
Production is believed to total 1 ,000 tons or less. The
limestone lenses apparently are too small to be of eco-
nomic interest. Several other carbonate masses are in-
dicated to the northwest in sees. 8, 13, and 14, T. 16 S.,
R. 3 E., and sees. 18, 19, and 21, T. 16 S., R. 2 E. by C.
L. Herold (1935, unpublished thesis); but these are
probably small and inaccessible. They have not been
examined. Two additional deposits of crystalline lime-
stone are reported by Oliver E. Bowen (1968, oral
communication) to underlie several acres of SW1/ sec.
9, T. 16 S., R. 3 E. at the head of San Benancio Canyon.
Limekiln Creek deposits (near Lucia). Location:
Sec. 10, SW'/4 sec. 11, NW1/ sec. 14, and sec. 15, T. 22
S., R 4 E., M.D., 1 to 2 miles east of Lucia; Lucia,
Junipero Serra, and Cape San Martin 15-minute quad-
rangles. Ownership: S. H. Cowell Foundation, 25 Cal-
ifornia Street, San Francisco, and U.S. Government
(1964).
Numerous small to moderate-sized deposits of car-
bonate rock are reported between the main and west
forks of Limekiln Creek. These are interbedded with
schist of the Sur Series and are commonly cut by dikes
of light and dark granitic rocks. Because carbonate
rock talus is so prevalent in sees. 10 and 1 5, the impres-
sion is given that an immense carbonate body exists
(see Reiche, 1937, p. 163 and map). However, Oliver
E. Bowen (1964, personal communication) reports
that the largest body present in this area is a northeast-
dipping rib of carbonate rock averaging perhaps 100
to 150 feet thick. The rib is situated near the S'/ cor.
sec. 10 and is best exposed on the west side of the main
spur south of "hill 2449". The deposit is a complex
mixture of massive, white, coarse-crystalline to platy,
gray, banded, fine-crystalline limestone. Some of the
limestone is dolomitic (cream-colored dolomite), and
much is siliceous. The carbonate rocks have been con-
tact-metamorphosed, forming various magnesium,
calcium, and aluminum silicates; and commonly they
have been brecciated and recemented. According to
Bowen, other impure carbonate masses are found in
the vicinity, but most are small and none is of suffi-
cient quality to be of significant economic interest.
Chemical analyses of samples from the prominent car-
bonate lens exposed near "hill 2449" in S1/ sec. 10 are
presented below. Analyses were made in 1964 by Mat-
ti Tavela and Lydia Lofgren of the Division of Mines
and Geology. The samples are typical of the limestone
and dolomite and probably represent the great bulk of
the deposit.
1978
1 ,IM F.STONE IN THE COAST RAMJFS
79
Ign.
Simple SiQ3 Fe/h Wh GO MjgO P*(h loss
LC-1 5.50% 0.13% 0.20% 51.50% 1.20% 001% 4190%
L&2 1.30 0.15 0.00 54.00 1.30 0.04 42.60
L&3 1.40 0.32 0.42 34 80 17.20 0.01 45.20
The above carbonate deposits apparently extend
discontinuously 6 miles to the southeast to the west
flank of Chalk' Peak in S'/2 sec. 28, T. 22 S., R. 5 E.
(figure 5). Near the middle of the carbonate belt,
where it crosses the connecting road between the
coast and Jolon, the limestone masses are too thin and
impure to be of commercial interest. Deposits farther
to the southeast near Chalk Peak, indicated by Jen-
nings (1958), have not been examined.
The only limestone development in the vicinity
took place during the 1880s by the Rockland Lime and
Lumber Company, which erected four vertical kilns
along the West Fork of Limekiln Creek (SW'/4 sec. 1 5,
T. 22 S., R. 4 E). Crushed and broken limestone from
a large landslide situated on the steep slope northeast
of the kilns was utilized. The company developed sev-
eral shallow hillside pits in the crushed limestone and
sledded the material down slope to the kilns. The
kilns, each of which had a capacity of 110 barrels of
lime per day, apparently were loaded overhead and
fired by wood. Lime was hauled to Rocklands Landing
about a mile away and loaded by aerial tramway
aboard waiting ships. Around 1890, the property was
acquired and shut down by Henry Cowell Lime and
Cement Company. It has been inactive since that time.
The quarry vicinity was examined briefly by this
writer in August 1959. Although good limestone un-
doubtedly was selected from the landslide debris for
calcining, not all of the limestone is of good quality.
Locally, the limestone is dolomitic and associated with
metamorphic and granitic rock much like the main
deposit higher on the spur. Some of the rocks appear
to be in place and either represent Sur Series beds
underlying a thin veneer of landslide debris or are
portions of a large, partly crushed block that slid
downslope from the main limestone mass. It is not
likely that further commercial development will take
place in this landslide area.
Other references: Irelon, 1888, p. 410; Crawford, 1894, p 392; Crow-
ford, 1896. p. 629, Aubury, 1906, p. 72; Logan, 1947, p. 259, Hart, 1966
b, p. 63.
Pacific Carrara Marble Company. A company by
this name was organized prior to 1880 to develop a
deposit of white limestone near Carmel Bay. There is
no record of production, but a small deposit of Sur
Series limestone near Big Sur is reported (unverified)
to be developed by a small, old quarry.
References: Honks, 1884, p. 110, logon, 1947, p. 260.
Pico Blanco deposit. Location: Sees. 25 and 36, T.
18 S , and sees. 1,2, 11, and 12, T. 19 S., R. 1 E, M.D ,
20 miles south of Monterey and 2 to 3 miles northeast
of State Highway 1; Big Sur 7'/2-minute quadrangle.
Ownership: Granite Rock Company, P. C). Box 151,
Watsonville, owns sec. 36 and controls adjacent unpat-
ented mining claims (1964).
The Pico Blanco deposit is probably the largest
mass of good quality, uniform grade limestone within
ISO miles of San Francisco. Although reserves appear
to be enormous, the deposit has never been developed
commercially because of its relatively inaccessible lo-
cation and distance from major sources of transporta-
tion.
Formerly, sec. 36 of the deposit was owned by Mrs.
C. L. Koch. This section was acquired about 1956 by
Tom Maher who also located claims in the vicinity.
Maher's holdings were obtained in the late 1950s by
Olaf P. Jenkins of Pacific Grove. Jenkins had the
deposit sampled and mapped in detail by M. E. Mad-
dock (1960, unpublished report) and M. E. Maddock
and C. C. Carlson ( 1961, unpublished report). Results
of these surveys are summarized by Hart (1966b, p.
63-66) and are largely repeated here. Granite Rock
Company acquired the Pico Blanco property about
1963 after leasing it for a short period of time.
The name Pico Blanco means "White Peak" in
Spanish and refers to the white limestone which caps
the summit and east and south flanks of the 3,709-foot
peak. The deposit, previously accessible only by foot
trails from the Old Coast Road and the Pico Blanco
Boy Scout Camp, can now be reached by jeep road,
completed in 1964, from the coast via Dani Ridge.
The deposit contains two bodies of crystalline lime-
stone of economic interest — known as the Pico Blanco
body and the Hayfield body — and numerous smaller
bodies of little commercial importance. The Pico
Blanco body is a thick, tabular mass exposed over an
irregular area measuring 2'/2 miles from north to south
(figure 6). The northern part of the body dips 35° to
55° NE and appears to be a homocline; but the south-
ern third is structurally complex, probably being a
faulted, southeastward plunging anticline. Southwest
of the Pico Blanco body is the Hayfield body located
in SE1/ sec. 1. T his mass of crystalline limestone blan-
kets the south slope of the peak and probably has a
maximum thickness of 100 to 200 feet.
In large part, the Pico Blanco and Hayfield bodies
consist of white or nearly white, coarse-crystalline
limestone composed almost entirely of calcite, with
minor amounts of quart/, and graphite. Local concen-
trations of granular quart/, in thin resistant bands ex-
ist, but they are quantitatively unimportant. Dolomite
also is found in some places as alternating bands or
disseminated crystals in the limestone. In one place
along the South Fork of the Little Sur River, banded
dolomite constitutes a horizon 40 to 50 feet thick.
Phlogopite (magnesium mica) in small "trains" and
other magnesium silicate minerals occur locally. The
dolomite, quartz, and silicate minerals present would
be considered impurities in most limestone uses, al-
though minor occurrences of these contaminants may
be diluted by quarrying with high-quality limestone.
so
California Division of Mines and Geology
Bull. 197
Figure 6. Geologic mop of Pico Blonco limestone deposit, Monterey
County.
1978
I IM1 s I ( )N'|- |\ | HI ("OAS I R S
Larger masses of impurities, w hich are not too com-
mon, generally can be avoided by selective mining. If
the limestone is used for cement, a high silica content
actually may be desirable. Other contaminating
materials associated with the limestone are schist and
Table 17. Chemical analyses of carbonate rock samples from
Pico Blanco deposit (see figure 6 for locations).
Simple
dO
MgO
PB-1
2.56%
0.08%
1144 %
5 \ 66%
0.46%
am",
PB-2
0.69
0.04
0.17
54.92
0.48
0.02
PB-3
3.90
0.12
0.92
52.56
0.48
0.03
PB-4
0.17
0.02
0.04
55.52
0.26
0.04
PB-5
6.12
0.10
1.27
51.43
0.19
0.05
PB-6
0.55
0.13
0.14
54.54
0.83
0.01
PB-~
0.27
0.02
0.08
55.70
0.07
0.02
PB-n
0.13
0.04
0.04
55.69
0.14
0.01
PB-9
0.50
0.07
0.12
55.30
0.24
0.04
PB-10
0.47
0.16
0.10
36.88
15.89
0.02
PB-1 1
0.31
0.08
0.08
55.56
0.14
0.03
PB-12
0.81
0.05
0.22
54.87
0.42
0.01
PB-1!
0.66
0.05
0.21
54.78
0.52
0.03
PB-14
0.20
0.06
0.08
55.58
0.18
0.02
PB-1 5
0.18
0.05
0.06
55.08
0.59
0.03
PB-16
2.78
0.03
0 88
53.29
0.42
0.01
PB-1 7
0.70
0.05
0.20
54.82
0.48
0.02
PB-18
0.84
0.06
0.24
54.89
0.36
0.02
PB-19
069
0.05
0.18
55.12
0.23
0.03
PB-20 *
0.84
0.13
0.21
42.40
10.96
0.03
PB-21
0.67
0.06
0.16
50.35
4.33
0.02
PB-22
1.01
0.04
0.23
54.59
0.49
0.02
PB-21
0.22
0.02
0.07
55.35
0.39
0.03
PB-25
0.62
0.02
0.13
55.00
0.37
0.05
SPB-1
0.94
0.47
0.20
53.47
1.30
0.11
SPB-2
0.76
0.08
0.13
51.14
3.66
0.05
SPB-3
0.32
0.06
0.07
52.36
2.80
0.05
SPB-4
0.21
0.05
0.05
55.21
0.49
0.05
PBv-lA
0.70
0.08
0.14
55.04
0.33
0.20
PBv-lB
0.52
0.05
0.06
55.09
0.43
0.07
PBv-lC
0.66
0.06
0.14
52.13
2.77
0.21
PBv-lD
0.58
0.05
0.10
53.81
1.43
0.20
PBv-2 •
23.40
0.14
0.38
42.28
0.17
0.05
PBv!
0.72
0.07
0.15
53.96
1.19
021
PBv-4
3.10
0.08
0.16
53.32
0.57
0.14
PBv-5
0.88
0.04
0.08
55.09
0.24
0.04
PBv-6
1.18
0.02
0.06
54.65
0.49
0.04
PBv-7
1.92
0.03
0.10
54.56
041
0.05
PBv-8
1.48
0.05
0.18
54.25
0.59
0.19
PBv-9
0.72
0.10
0.20
55.17
0.18
0.20
PBv-10
2.16
0.16
0.32
54.01
0.38
0.20
PBv- 11
" 12
0.19
0.36
50.47
0.71
0.26
PBv-12A
3.92
0.11
0.23
52.83
0.53
0.21
PBv-l2B "
1.12
0.06
0.12
35.30
16.95
0.01
PBv-l! •
17.94
0.19
0.22
44.83
0.58
0.04
PBv-14
0.70
0.08
0.16
54.71
0.64
0.20
PBv- 15
0.44
0.03
0.11
54.31
1.08
0.19
PBv-16
1.74
0.04
0.14
54.58
0.23
0.05
• Sample analyzed lo determine range of Si02 or MgO or for other special
purposes.
Samples PB-1 lo PB-12 collected by Oliver E. Bowcnand Earl W Hart March
27, 1957, and analyzed by Abbot A. Hanks, Inc., San Francisco.
Samples PB-H to PB-25 collected by Oliver E Bowen June 27. 1957, and
analyzed by Abbot A. Hanks, Inc.
Samples SBP-I lo SBP-4 collected by l orn Maher (previous owner) March
1958 and analyzed for Division of Mines by Abbot A. Hanks, Inc.
Samples PBy-1 to PBy-16 collected by Marshall E Maddock October I, 1959,
(outcrops painted yellow) and analyzed by Abbot A. Hanks, Inc (per-
mission to publish courtesy O P Jenkins, owner).
gneiss interbeds and granitic dikes. These rocks usu-
ally are restricted to the marginal parts of the lime-
stone bodies and may not present serious mining
problems.
Through early 1961, development of the Pico Blan-
co deposit had been restricted to sampling and geolog-
ic mapping. A few test pits have been developed on the
claims as a part of the assessment work and, since 1961,
limited core drilling has been done, but drill data are
not available.
Prior to 1961, samples from 44 localities (figure 6)
were analyzed for chemical composition (table 17).
Although an insufficient number of samples was
analyzed to delineate areas of various quality lime-
stone, sampling and field inspection indicate that the
great bulk of the Pico Blanco and Hayfield bodies
consists of good quality limestone that averages about
54 percent lime. It is apparent that the limestone is of
sufficiently high quality for cement. Moreover, analy-
ses suggest that some of the limestone is adequate for
most lime, chemical, and metallurgical uses.
Reserves cannot be estimated accurately because ex-
act thicknesses of the bodies are not known. However,
if it is assumed that the Pico Blanco body has an aver-
age thickness of 500 feet, maximum limestone reserves
north of the South Fork of the Little Sur River and
above 1,600 feet elevation are estimated to be in the
order of 600 million tons. Although parts of the depos-
it are thinner than 500 feet, a maximum thickness of
over 1,500 feet is estimated by Marshall E. Maddock
(1960, unpublished report for Olaf P. Jenkins), and
the reserve estimate is probably conservative. On the
other hand, reserves could be reduced significantly
depending on the quality and uniformity of limestone
required for a particular use, the amount of selective
mining necessary, and the amount of deleterious
materials associated with the limestone. The max-
imum reserves of the Hayfield body north of the river
are estimated to be about 20 million tons, assuming an
average thickness of 100 feet.
By any standard, the Pico Blanco body is enormous
and obviously of strong economic potential. The most
serious drawback to its development is its relatively
remote location, especiallv with reference to markets
or established major transportation lines. Its location
in an area of potentially high recreational and wilder-
ness value may also present some development prob-
lems. 'The owners are reported to be exploring the
feasibility of various alternative methods of extraction
and transportation that would permit development
with minimal impact on other values.
Other references. Trosk, 1926, p. 131, mop,- Logon, 1947, p. 260.
Sierra (Serra) Hill-Little Sur deposits. S'/, T. IX
S., R. 1 E., M.D., extending from the NW'/4 sec. 19
southeastward to the E1/, cor. sec. 34, accessible from
State Highway 1 and the Old Coast Road; Point Sur
15-minute quadrangle. Ownership: Not determined
(1957).
8 2
California Division of Mines and Geology
Bull. 197
Several sinuous lenses of carbonate rock as long as
a mile are shown on Trask's geologic map (1926).
These lenses, plus some small nearby masses, form a
discontinuous belt 4'/2 miles long extending from the
sea coast just north of Hurricane Point southeast to
the western part of Dani Ridge. The limestone is part
of the Sur Series of metamorphic rocks which locally
have been thrust southwestward over Cretaceous (?)
sedimentary rocks along the Serra Hill fault (Trask,
1926, map and fig. 2). There has been no development
or even significant testing of the limestone, and little
is known about the commercial possibilities. The most
northwestern lens of limestone was observed briefly
where it is crossed by State Highway 1, Here it is
brecciated and somewhat impure, being associated
with schist and locally cut by granitic dikes. Two se-
lected samples of limestone, collected from the high-
way cut at the northwest end of the deposit belt, were
analyzed in 1955 and 1957 by Abbot A. Hanks, Inc.
Sample SiO, Fe.O, A/.O, CaO MgO P,Q,
SLS-1 0.56% 0.08% 0.30% 54.13% 1.02% 0.04%
Sil l 0.65 0.05 0.16 53.47 1.69 0.02
These samples are nearly white, fine- to coarse-crys-
talline material and represent the best limestone avail-
able near the highway- However, this part of the
deposit probably is not of commercial value due to
siliceous impurities and granitic intrusives which
were not sampled. Although the southeastern lime-
stone lenses also may be impure and less continuous
than indicated by Trask, their relative accessibility
warrants further examination and possible sampling
(Hart 1966b, p. 66).
Tassajara deposit. Location: NE'/i sec. 29, T. 19 S.,
R. 4 E., M.D., 17 miles west of Greenfield; Jamesburg
15-minute quadrangle. Ownership: Not determined.
A small deposit of white crystalline limestone was
quarried many years ago as a source of lime for mortar
in construction of the hotel at Tassajara Hot Springs
(Fiedler, 1944, p. 203, 248, plate 9). The deposit is
situated on Tassajara Road less than 3 miles north of
the hot springs. Although easily accessible, the lime-
stone is remote and impure, being cut by pegmatite
dikes.
PARKFIELD-COALINGA DISTRICT (C-4)
Several deposits and prospects of carbonate rock
dispersed over parts of Monterey and Fresno Counties
are designated herein as the Parkfield-Coalinga dis-
trict. Except for a minor amount of "brown arago-
nite" (Montford deposit) used to make lime in the
lKKOs, none of the deposits is developed.
Perhaps the most important deposits are the discon-
nected masses of crystalline limestone and dolo-
mite (?) (Little Cholame and Nelson Creek deposits)
which occur as fault slivers along the San Andreas
fault zone. Some fault slices of fine-grained limestone
similar to that of the Franciscan Formation also exist
along the San Andreas fault zone. Because of their
remoteness from marketing areas, none of these
deposits has been prospected to any extent. The other
limestone and dolomite deposits reported appear to be
too small or impure to be of more than strictly local
interest.
Little Cholame (Patriquin) deposits. Location:
SW'/4 sec. 31, T. 22 S., R. 14 E., and SW'/4 sec. 5 and sec.
6, T. 23 S., R. 14 E., M.D., 5 miles northwest of Park-
field and 15 miles southwest of Coalinga; San Miguel
and Parkfield 15-minute quadrangles. Ownership:
Not determined (1962).
An "undeveloped deposit of white marble" in sec.
6 is mentioned by Waring and Bradley (1919, p. 607).
This undoubtedly is part of the sequence of three fault
blocks or slivers of Sur Series limestone shown by
Jennings (1958, based on unpublished mapping of N.
L. Taliferro). The limestone supposedly extends 2'/2
miles southeast along the San Andreas fault zone from
SW1/, sec. 31 to E'X cor. sec. 8. Examination of the
southeast fault block in sec. 8 was made, but not a
single exposure of limestone was observed. However,
numerous fragments of white to gray, crystalline
limestone were noted in the ravines and in the late
Cenozoic gravel deposits exposed on the hills. To the
northwest in SE% sec. 5, limited exposures of lime-
stone could be seen but were not visited. The deposit
indicated in sees. 5, 6, and 31 to the northwest is likely
to consist of small fault blocks and slivers of crushed
and sheared limestone interspersed with other rock
types, as is the case to the northwest along the San
Andreas fault zone (see Nelson Creek deposit).
However, this inference cannot be substantiated with-
out additional field work.
Other references. Logon, 1947, p. 260; Hart, 1966b, p. 67, 69.
Montford deposit. Location: Sec. 24, T. 21 S., R.
14 E., M.D., 4 to 5 miles southwest of Coalinga; Coa-
linga 15-minute quadrangle. Ownership: Not deter-
mined.
Brown aragonite was reported in 40 acres of land
owned by Dr. G. T. Montford (Laizure, 1929, p. 317).
Logan (1947, p. 234) refers to this property as Mont-
ford marl — "a 'vein' of limestone" from which lime
was made in the 1880s. The limestone is reportedly
bituminous.
Nelson Creek deposits. Location: Mainly sec. 22,
SW'/4 sec. 23, and N'/2 sec. 26, T. 22 S., R. 13 E., M.D.,
17 miles northeast of Bradley and 15 miles southwest
of Coalinga. Ownership: Possibly Hope Bagby, Hid-
den Valley Ranch, San Miguel (1960).
Blocks and slivers of crystalline limestone and dolo-
mite (?) intermixed with Sur Series schist, granitic
rocks, Franciscan rocks, serpentine, and various
younger sedimentary rocks are found along the San
Andreas fault zone on the northeast side of Nelson
Creek. The carbonate rocks reportedly are exposed
over a distance of more than 2'/2 miles from NW cor.
1978
I.IMI SIONI l\ llll C()\SI K S
83
sec. 22 southeast to W1/ cor. sec. 25 (N. L. Taliaferro
in Jennings, 1958, and in Jennings and Strand, 1958).
Where examined in SE'/4 sec. 22 and SW'/i sec. 23, the
only carbonate rock exposed is limestone in small
blocks and slivers not more than 30 to 40 feet wide and
interspersed with other rock types. The limestone is
principally blue gray, medium to coarse crystalline,
sheared, and brecciated. Samples of typical rock were
analyzed by Lydia Lofgren of the Division of Mines
and Geology on February 15, 1963, as follows:
Ign
Simple CiO MgO SiO- M.Q, Fe.O, P..O, loss
1 49.70% J.08% 4.44% 0.10% 0.20% 0.04% 42.39%
2 54.50 0.17 1.03 0.11 0.23 0.04 43.27
In addition to the above type of limestone, off-white
to gray crystalline limestone and dolomite are found
as float in Nelson Creek and its tributaries. Presuma-
bly, this float was derived from small broken masses
(to the southeast, in sec. 26 ?) similar to those faulted
masses examined in sees. 22 and 23 Although total
limestone reserves may be large in the Nelson Creek
area, the deposits appear to be too intermixed with
other rocks and too remotely situated to be of econom-
ic interest. The deposits are about a mile from the
Nelson Creek road which is about 24 miles (by road)
from San Miguel.
Other references: Crawford, 1894, p. 392; Crawford. 1896, p. 629; Logan,
1947, p 259; Hart, 1966b, p. 67, 69.
Stone Corral deposits. Location: Sees. 25 and 36
(proj.), T. 24 S., R. 15 E., and sec. 31, T. 24 S., R. 16
E., M.D., 9 to 1 1 miles southeast of Parkfield, Parkfield
15-minute quadrangle. Ownership: Probably Cho-
lame Ranch (1966).
Several masses of limestone are shown northeast of
Cholame Valley by VV. R. Dickinson (1966, plate 2).
These are portrayed as lens- and wedge-shaped fault
slices that are distributed along a fault zone for 2 miles
northwest of Stone Corral Canyon. The largest lime-
stone mass has maximum dimensions of 4,500 feet by
1,200 feet. The limestone is gray green and reddish
gray, fine grained, and commonly sheared. It contains
dark gray chert bands and nodules and resembles
limestone of the Franciscan Formation (Dickinson,
1966, p. 718).
The above deposits have not been examined by this
writer.
Webb and Mingus calcite deposit. Location: Sec.
12, T. 20 S., R. 13 E., M.D., 10 miles northwest of
Coalinga; Priest Valley 15-minute quadrangle. Own-
ership: Not determined.
A calcite deposit is reported on "Sherman Peak"
(Laizure, 1929, p. 317; Logan, 1947, p. 235). Recent
maps show Sherman Peak to be in sec. 10 to the west.
There is no known development of the deposit. Sec. 1 2
is underlain by sedimentary rocks of Late Cretaceous
age.
Webb and Mingus dolomite deposit. Location:
Sec. 28(?), T. 24 S., R. 16 E., M.D., 12 miles southeast
of Parkfield. Ownership: Not determined.
Laizure ( 1925, p. 36) mentions an undeveloped
deposit of dolomite in sec. 28 on the 160-acre property
of E. A. Webb and S. M. Mingus in southeast Monte-
rey County. Sec. 28 is shown to be underlain by com-
plexly faulted and folded clastic sedimentary rocks
(Upper Cretaceous and Tertiary) and by brecciated
serpentine by Dickinson (1966, plate 2), who makes
no mention of dolomite in his description of these rock
units. However, Dickinson does show several masses
of limestone l'/2 to 2 miles to the west (see Stone
Corral deposits).
SOUTHERN SANTA LUCIA RANGE DISTRICT (C-5)
The southern Santa Lucia Range district includes
the southeast half of the Santa Lucia Range, La Panza
Range, and uppermost Salinas River in San Luis
Obispo County (plate lC). Although not quite as
rugged as the northern Santa Lucia Range, the south-
ern Santa Lucia and La Panza Ranges are nonetheless
mountainous — rising to maximum elevations of 3,594
feet and 4,054 feet, respectively. Most of the district is
fairly accessible by roads and the Southern Pacific
Railroad traverses the region from north to south,
connecting all major communities. Limited port facili-
ties (oil, fishing) exist at San Luis Obispo and Estero
Bays. The district is about half way between the major
marketing centers at Los Angeles and San Francisco,
the two cities being 400 miles apart.
Limestone and dolomite of the southern Santa
Lucia Range district occur primarily as pre-Creta-
ceous metamorphic rocks and Miocene sedimentary
rocks. The metamorphic rocks are similar to the crys-
talline carbonate rocks of the Sur Series farther north.
In this district, crystalline limestone is found at the
Navajo deposit (see below) and also is reported in
SW'/( sec. 24, T. 30 S., R. 17 E., both localities being in
the La Panza Range. Localized in the northwest part
of the district is bioclastic limestone of the Vaqueros
Formation (lower Miocene). The two main occur-
rences are the Lime Mountain and Dubost deposits.
Other Miocene shell deposits are reported near the
Oceanic and Buena Vista mercury mines, 4 to 5 miles
inland on San Simeon Creek and at various places in
the Huasna and Salinas Valleys (Irelan, 1888, p. 532;
Fairbanks, 1904, p. 4; Logan, 1947, p. 303, 306). These
shell beds belong to the Vaqueros and Santa Margarita
formations of early and late Miocene ages, respective-
ly. Some of the shell beds, or reefs, are composed al-
most totally of shells and shell debris, one reportedly
being 30 feet thick or more (Fairbanks, 1904, p. 4).
Although some shell beds have been used locally as
sources of lime, few if any are large enough or pure
enough to be of economic interest.
In addition, impure carbonate rock constitutes the
bulk of a thick sequence in the lower part of the Mon-
S4
California Division of Minks and Gkology
Bull. 197
terey Formation and its lower to middle Miocene
equivalents. The carbonate sequence is well developed
in the southern part of the district, one sequence being
300 feet thick in Lopez Canyon. However, the carbon-
ate beds are impure, consisting of siliceous, limy dolo-
mite and dolomitic limestone interbedded with
calcareous (foraminiferal) and dolomitic shale (see
Lopez Canyon deposits). Impure calcareous and do-
lomitic beds in thick lower to middle Miocene se-
quences also have been mapped to the southeast in the
Nipomo 15-minute quadrangle (Hall and Corbato,
1967) and to the northwest in the San Luis Obispo
15-minute quadrangle by this writer (unpublished).
Except for the hard, often blocky dolomite, which is
of value mainly for crushed rock purposes, these im-
pure deposits probably offer little economic potential.
Younger deposits of marl and impure limestone ap-
parently have been used locally as sources of lime but
are no longer of commercial consideration. The wide-
spread Jurassic and Cretaceous formations are not
known to contain important amounts of limestone in
this part of the Coast Ranges, although veins of coarse
crystalline limestone cut these formations (Tassajara
deposit) .
At least eight deposits have been productive, but
only the Lime Mountain deposit has been worked in
the last 30 years or more. Prior to that, beginning in
the 1880s, six of the deposits were worked locally as
sources of lime rock and one (Kesseler) provided
onyx marble for ornamental use. The Lime Mountain
deposit is still active and has yielded the only substan-
tial production of limestone in the district. Most of the
limestone produced there has been used for beet-sugar
refining. No other important source of high-grade
limestone is known in the district. However, moder-
ately large reserves of cement-grade limestone are
available at the Navajo, Lime Mountain, and Dubost
deposits. Although none of these alone may be large
enough to support a cement plant, it may be possible
to utilize the adjacent Lime Mountain and Dubost
deposits cooperatively. Considering the great distance
from large marketing centers, however, none of the
deposits of the southern Santa Lucia Range district is
likely to be developed for regional use in the near
future.
The limestone deposits of the district are described
alphabetically below.
Almaden deposit. Location: SW'/4 sec. 34, T. 26 S.,
R. 10 E., M.D., 1 1 miles west of Paso Robles; Adelaida
15-minute quadrangle. Ownership: Not determined.
Fossiliferous limestone at an elevation of 1,500 feet
is reported by Logan (1947, p. 306). Eckel et al. ( 1941,
p. 557) report limestone to the east of the Mahoney
(Huena Vista) mercury mine in the same vicinity.
There is no known development of the Almaden
deposit.
Aumaier and Rodriguez deposit. Location: Proba-
bly sec. 30 or 31, T. 30 S., R. 13 E., M.D., 7 miles
east-northeast of San Luis Obispo; San Luis Obispo
15-minute quadrangle. Ownership: Not determined;
probably U.S. Forest Service (1965).
S. Aumaier and Peter Rodriguez located a claim of
dolomite prior to 1925, reportedly in "sec. 1 3, T. 30 S.,
R. 13 E., at the upper end of Little Falls Canyon"
(Laizure, 1925, p. 513). An analysis of the dolomite,
made by Smith, Emery and Co., showed 20.44% MgO,
31.70% CaO, 0.40% Si02, 0.19% A1203, 0.05% Fe203,
and 47.36% ignition loss. It should be noted that "Lit-
tle Falls Canyon" is now known as Big Falls Canyon,
the head of which lies in sees. 30 and 31, T. 30 S., R.
14 E., and does not extend as far northwest as sec. 13.
The section location given by Laizure probably is
inaccurate. The dolomite deposit in question may be
the same as the "vein of white crystalline dolomite"
described in "Little Falls Canyon" by Fairbanks
(1904, p. 14).
Other references: Auburyl?), 1906, p. 80; Franke, 1935, p. 420.
Dubost deposit. Location: NW'/4 sec. 30, T. 26 S.,
R. 10 E., and NE'/4 sec. 25, T. 26 S., R. 9 E., M.D., 14
miles west of Paso Robles, which is reached over 20
miles of good roads; Adelaida 15-minute quadrangle.
Ownership: Marion F. Davis, Adelaida Route, Paso
Robles (1962).
Limestone from the Dubost deposit was burned for
lime many years ago by A. Gould (Aubury, 1906, p.
79) . According to W. L. Stanton, Jr. ( 193 1, California
Institute of Technology unpublished thesis), two
kilns were built here; one in 1890 near the "Dubost
home" (Camp Natoma) and the other in 1894 "over
the hill and down the creek" (Franklin Creek?) . Stan-
ton states that the kilns were last operated in 1912.
Although records are lacking, production is believed
to have been small, as no extensive quarry site is
known. Frank and Mary Dubost owned the deposit
for many years prior to 1955, when it was acquired by
the present owner.
The Dubost deposit consists of a sequence of mas-
sive limestone and minor sandstone beds that are part
of or correlative with the Vaqueros Formation of early
Miocene age (Loel and Corey, 1932, p. 102-104, 136-
137). The limestone unit rests on sandstone of proba-
ble Late Cretaceous age and is overlain by soft shale
of the Monterey (?) Formation. These sedimentary
rocks have been broken into three or more fault
blocks, which are successively downdropped to the
northeast. Older Franciscan rocks have been brought
up along Las Tablas fault, thus truncating the deposit
on the south. The deposit consists of a main body of
limestone and two smaller (thinner) sequences of
beds to the northeast (figure 7). Obscure bedding fea-
tures suggest a general south or southwest dip for the
bodies, but local variations exist.
Most of the limestone is a pale buff, dense material
composed almost entirely of sand-sized shell frag-
ments cemented with calcite. Quartz, feldspar, and
other impurities constitute a small percentage of the
1978
I IMISTONI l\ I III COASI K\\(.ls
85
typical limestone. Subordinate interbeds of gray to
buff, pebbly coquina, calcareous sandstone, and simi-
lar rock types constitute the less pure portions of the
deposit. A representative sample (Dubost # 1) of typi-
cal limestone from the main body was analyzed by
Lvdia Lofgren of the Division of Mines and Geologv
in 1962 and showed 51.4% CaO, nil MgO, 5.01%
Si()2, 0.5% Al203, 0.25% Fe203, 0.05% P205, and
41.34% ignition loss.
I he largest bod\ of limestone underlies "hill 1905"
west of Camp Natoma (figure 7). The limestone,
which is almost continuously exposed over the crest
and south side of the hill, extends over an elliptical
area half a mile long by a maximum of 900 feet wide.
Most of the limestone appears to be relatively uni-
form, although two or three impure sandy and pebbly
beds were observed. The thickness of the body is not
known but probably is a minimum of 100 to 200 feet
to cover the hill so thoroughly. Limestone reserves are
estimated to be on the order of 120,000 tons per foot
of depth and may total 20,000,000 tons or more. Addi-
tional limestone, extending half a mile west of "hill
1905" to Franklin Creek, is reported by W. L. Stanton,
Jr. (1931, California Institute of Technology unpub-
j- Vogueros Formation (Miocene)
Jf Franciscan Formation (Jurassic ?)
?- Faults
doshed where locoted approximately
queried where inferred
Figure 7. Geologic mop of Dubost limestone deposit. Son Luis Obispo County.
86
California Division of Mines and Geology
Bull 197
lished thesis), who considers the exposures to be possi-
bly "continuous or nearly so" with the main body.
The exposures were not examined by this writer.
Two thin, subparallel bodies of limestone, probably
separated by a fault, lie northeast of the main body.
Bedding attitudes could not be measured, but overall
distribution of limestone suggests the bodies are thin
and dip moderately to gently toward the southwest.
Reserves are difficult to estimate without drill data
but probably are relatively small.
Development of the Dubost deposit has been lim-
ited to minor production of limestone (for lime), al-
though there were two episodes of exploratory
drilling. In 1946, H. W. Gould and Company held a
lease on the property and did extensive core drilling,
part of which was conducted north of the main depos-
it on the lower of two terraces (Logan, 1947, p. 303).
Fourteen holes totaling 1,742 feet were drilled and an
average analysis of 91.32% CaO and 5.17% Si02 was
computed for the samples obtained. The few samples
analyzed for magnesia contained less than 0.25%
MgO. The company estimated (preliminary) lime-
stone reserves at more than 50 million tons although
only 1 to 2 million tons were proved by drilling (Lo-
gan, 1947, p. 304). From 1955 to late 1962, Collier
Carbon and Chemical Corporation leased the deposit
and did additional diamond drilling, including both
vertical and diagonal holes in the main body. Results
of that program are not available.
Future potential of the Dubost deposit is somewhat
uncertain because of the size, location, and quality of
the limestone. Based on quality alone, the limestone
undoubtedly would be satisfactory for cement and
certain other purposes but not for lime, chemical, and
other uses where high chemical quality is important.
Reserves of this deposit may be insufficient to estab-
lish a cement plant.
Huasna area. Location: NW/4 T. 32 S., R. 16 E.
and E'/2 T. 32 S., R. 15 E., M.D., 13 to 18 miles east of
Arroyo Grande; Nipomo 15-minute quadrangle.
Ownership: Not determined.
According to Aubury (1906, p. 80), "an extensive
deposit of buff colored limestone" is situated on the
properties of Dawson, Lowe, and Mrs. R. Porter, as
well as on U.S. Forest Service land. The area referred
to is underlain extensively by the Monterey Forma-
tion, which commonly contains calcareous (forami-
niferal) mudstone and siltstone beds, as well as
impure dolomite. However, there are no deposits of
limestone known to be of economic interest in the
Huasna area. A description and geologic map of the
rock units of this area are given by Hall and Corbat6
(1967).
Kesseler (Kessler) deposit. Location: Sees. 9 and
16, T. 31 S., R. 15 E., M.D., 14 miles northeast of
Arroyo Grande; Nipomo 15-minute quadrangle.
Ownership: Not determined.
Irregular masses of onyx marble and related carbon-
ate material are exposed intermittently over a length
of half a mile in the vicinity of Salt Creek. The masses
are found in sandstone and shale, apparently as frac-
ture fillings related to the East Huasna fault. The
following description of the deposit is based largely on
reports by Angel (1890, p. 584-585) and Aubury
(1906, p. 111-112). At the main quarry to the east
(south?), the onyx occurs as steeply dipping layers 1
to 10 inches thick and varies from white to yellow,
green, and red. Half a mile to the west (north?), the
stone is white, faintly banded, and occurs in two lay-
ers 1 to 6 inches thick. Other small masses of carbonate
rock are found on the hill between the above expo-
sures. A chemical analysis of the onyx shows 93.86%
CaCO,, 1.43% MgCO,, and 3.93% FeCO, (Waring,
1915, p. 165). Several saline springs and seeps are ac-
tive in the vicinity and probably are related to the
formation of the onyx.
The Kesseler deposit was worked from about 1890
to 1900 through two quarries half a mile apart. The
main (east) quarry was developed over a length of 50
feet and a height of 20 feet, exposing onyx marble 15
feet thick. Because the marble took a good polish and
could be obtained in large slabs, it was shipped widely
for ornamental uses. Total production is reported to
have been more than 1,000 tons prior to 1900. Later
attempts to develop the deposit were unsuccessful.
However, the deposit has been utilized informally as
a mineral collecting site, and much onyx marble has
been taken for lapidary purposes in recent years.
Other references: Laizure, 1925, p. 527; Franke, 1935, p. 432.
Lime Mountain deposit. Location: Sees. 15 and
16, T. 26 S., R. 9 E., 18 miles west of Paso Robles;
Adelaida and San Simeon 15-minute quadrangles.
Ownership: Eaton and Smith, 1215 Michigan Street,
San Francisco (1963).
The Lime Mountain limestone deposit has been un-
der development since 1932, and production has been
substantial. According to Logan (1947, p. 304-305)
and unpublished data, commercial production was in-
termittent between 1933 and 1943 by Charles Taylor
and in 1945 by San Miguel Lime and Development Co.
Based on the sizes of the quarries reported by Logan,
total amount of limestone quarried prior to 1946 prob-
ably was about 200,000 tons, well over half of which
must have been sold. Records indicate that subsequent
production in 1947 and in 1949 was by Essential In-
dustries, Inc., and between 1952 and 1953 by Henry C.
Dalessi, the latter operating the property for the Cen-
tral Bank of Oakland. The present owner acquired the
deposit in late 1953 and has operated it on a seasonal
basis ever since. Total limestone produced (sold)
through 1963 is estimated to be more than a million
tons. All of the limestone quarried was obtained from
the summit area of the main limestone body in NW/4
sec. 15 and virtually all of the production was for use
in beet-sugar refining.
1978
LlMFSTONK IN 1111 C.OASI R.\N(;FS
87
This deposit consists of a main body of limestone
and several smaller masses lying nearby to the east and
to the south (figure 8). The main body is exposed at
the summit and south face of Lime Mountain through
a relief of 1,000 feet. It is about a mile long in a N 65°
\V direction, extending from a point just west of the
center sec. 15 into the NW'/4 sec. 16, and is 1,000 to
2,400 feet wide. On the south flank of the mountain in
SE'/i sec. 16 and the adjacent part of sec. 1 5 is a smaller
northwest-trending limestone body roughly 2,000 feet
long by a maximum of 900 feet wide. Additional lime-
stone outcrops flank the main body to the east and
northeast and probably represent twro or three sepa-
rate small bodies, one being about 50 feet thick near
the paved road. The boundaries of the several lime-
stone masses are partly obscured by soil and dense
vegetation on the north slope of Lime Mountain and
by waste dumps at the east end of the main body.
According to Taliaferro (1944, figure 9), the lime-
stone is part of the \ aqueros Formation (lower Mio-
cene), which rests unconformably on Upper
Cretaceous sedimentary rocks. The finer grained
limestone is virtually identical to the Yaqueros lime-
stone exposed in the Dubost deposit 3 miles to the
southeast.
Because bedding features are seldom well defined,
the thickness and gross structure of the deposit are
difficult to ascertain. The main limestone exposures
on the south slope of the mountain appear to be essen-
tially a dip slope, although local variations in bedding
attitudes, as well 'as brecciation features, suggest that
the deposit is disrupted by faulting. As a result, the
thickness of the limestone sequence is not known. An
estimated minimum thickness of 100 to 200 feet is
indicated by the large outcrop area and is partly veri-
fied by quarrying which, since 1932, has descended
more than 100 feet below the 1947 summit elevation of
2,230 feet. Additionally, drill holes have penetrated as
much as 60 feet of limestone below the present lowest
quarry level, showing an original total of more than
160 feet of limestone at the summit (W.J. Smith, 1962,
personal communication).
Several grades and types of limestone are found in
the deposit, but the ratios and stratigraphic relation-
ships of the various types are not known. The
predominant limestone in the quarry area is light-
.4.
i
-
m 4
Photo 15. Looking west at moin quarry of Lime Mountain limestone deposit, August 1968. Quorry, situated at summi.
of lime-grade limestone in Coast Ranges and is used for beet-sugar manufacture. Photo courtesy of W. J. Smith of Eaton and Smith
t of Lime Mountain, is principal source
California Division of Mines and Geology
Bull 197
R 9 E.
CAMP ROBERTS
MILITARY RESERVATION
*Se>«ijr * Son Miguel
't25S
I
■%^JMAP AREA
<!, ' I Paso Robles
\ -
Location Map
22
T 26 S
J_
EXPLANATION
'^(y/^ Limestone of Vaqueros Formation
Y//////A (Miocene)
silts
JK
Siltstone
Jurassic and Cretaceous rocks
undivided (ss = sandstone)
/ Strike and dip of bedd
nq
— ?
Contacts (dashed where approx )
Inferred contacts (based partly on
data from others)
Faults (queried where inferred)
Main quarry
South quarry
Waste and storage dumps
Figure 8. Geologic map of Lime Mountain limestone deposit. Son Luis Obispo County.
1978
LlMKSTOM IN Mil COASI RaNCJK.S
89
buff, hard, compact, high-calcium coquina. This is
composed almost entirely of shell fragments and cal-
cium carbonate cement with minor amounts of quartz
and rock grains. Small amounts of dove-gray, bitumi-
nous coquina also are present in the southwest part of
the quarry. The limestone is commonly brccciated
and fractured, the fissures being partly filled with
dripstone or aragonite crystals. The coarse-grained
limestone crops out as craggy, soil-free exposures that
weather gray. To the east of the quarry, much of the
limestone is pale-buff, moderately hard, fine- to me-
dium-grained material composed of sand-sized grains
of shell debris cemented with calcite. Quartz grains
and other impurities commonly constitute several
percent of the finer-grained limestone, which weath-
ers to more subdued exposures than the purer lime-
stone. Other rocks that are occasionally interbedded
with the limestone include pebbly, fossiliferous sand-
stone and gray shale. Between the main deposit and
satellite outcrops to the south and east, siltstone and
other non-carbonate rocks are sporadically exposed.
Chemical analyses of the more common types of lime-
stone are given in table 18.
Table 18. Chemical analyses of limestone from the
Lime Mountain deposit, San Luis Obispo County.
Ign
Simple CM Mg() SKI, A/°()j Fe^Oj PsCh loss
Lime Mtn. 1 46.80% 0.63% 12.66% 1.18% 0.60% 0.03% 37.67%
Lime Mtn. 2 53.36 0.34 2.62 0.37 0.25 0.05 42.15
Lime Mm. 3 54.50 0.0 0.97 0.17 0.1 0.02 43.60
Lime Mtn. 4 54.70 0.0 0.76 0.12 0.09 0.02 43.73
Lime Mtn. 5 54.50 0.0 1.03 0.18 0.09 0.05 43.56
Samples collected November 1V62 by F.arl W. Hart. No. 1 is common sandy
limestone west of main quarry; no. 2 is dove-gray, bituminous coquina
from southwest part of main quarry; nos. 3 and 4 are typical high-grade
coquina from sugar-rock stockpile; no. 5 is composite from sugar-rock
stockpile Analyzed by Lydia Lofgren, February 6, 1963.
Development by the present owner has been con-
ducted in the main quarry and in a surrounding
stripped area and traces of all previous quarries, as
well as the original summit topography, have been
obliterated. The stripping program — initiated in 1958
to remove relatively low-grade (minus 95% CaCC)3)
limestone, soil, and a 2-foot gray shale bed — was near-
ly complete in late November 1962. The stripped area
is roughly circular, measures about 1,000 feet in diam-
eter, and surrounds most of the main quarry. The
owner said that as much as 60 to 70 feet of overburden
had been removed in places. The main quarry is some-
what irregular in shape but is judged to be about 800
feet long by a maximum of 400 to 500 feet wide, with
the long axis trending west. The north and south faces
are estimated to be 60 to 70 feet high and 50 feet high,
respectively, and are developed by 20- to 25-foot
benches. It is planned that the main quarry, now
worked from the east, will be developed from a quarrv
being opened on the south flank of the mountain.
Benches are currently blasted in air-drilled holes set
on 8- to 10-foot centers. Approximately half a pound
of ammonium nitrate is used per cubic yard of rock
and 3,000 to 10,000 cubic yards of rock is dislodged per
blast. Some secondary blasting also is necessary. The
rock is loaded by two power shovels (2'/,- and 1 '/,-vard
capacities) into end-dump trucks, hauled a short dis-
tance to the southeast side of the quarry, and dumped
into a hopper for processing. Some selective quarry-
ing is necessary to maintain a high-grade product.
Another quarry, called the Sycamore Springs pit,
was opened recently and was vielding lime-qualitv
rock averaging nearly 98% CaC03 (W. J. Smith, 1969,
personal communication). This quarry is believed to
be located in the satellite deposit just north of SYV
corner sec. 15.
Eaton and Smith's processing plant is located just
southeast of the main quarry. Here, raw rock dumped
in the hopper is fed over a vibrating grizzly with 8-
inch openings, and the oversize is crushed in a 30-inch-
by-42-inch jaw crusher. The crushed material joins the
minus 8-inch rock from the grizzly and all goes to a
double-deck vibrating screen with 3-inch and 8-inch
openings. Oversize and undersize fractions are con-
veyed to separate "waste" piles for possible future use.
The 3-inch-bv-8-inch product is stored in a 225-ton
bunker and in open stockpiles for subsequent ship-
ment by truck 27 miles to the railroad loading facility
at San Miguel. The product is then shipped by rail to
sugar refineries at Spreckels and Tracy. The sugar
rock produced averages close to 97% CaC03, fluctuat-
ing from 96 to 98.8%.
In 1962, the owner was experimenting with an agri-
cultural limestone product which is obtained at the
fines "waste" pile. Here, minus '/4-inch material is
screened and processed to obtain a minus 14-mesh
product. The product is trucked to the San Joaquin
Valley where it is sold as "Lime Mountain Brand Ag-
ricultural Limestone." A minimum of 80% CaC03 is
guaranteed, but the company reports that the product
generally contains 90% or more CaC03. The present
operator also occasionally sells minor amounts of or-
namental stone, riprap, crushed rock, and rubble to
local buyers.
Recent production (sales) of limestone has aver-
aged about 100,000 tons per year, virtually all of which
was sugar rock. The company reports that this
amounts to about 65% of the material currently proc-
essed, the remainder being largely unsalable (W. J.
Smith, 1962, oral communication). The operator em-
ploys 14 men at the quarry and plant and 18 to 20 truck
drivers and mechanics during much of the year. In the
winter, only a skeleton crew is retained to repair and
maintain roads and equipment and to strip overbur-
den and low-grade rock.
Total limestone reserves at Lime Mountain are not
known, although Logan (1947, p. 304) states that
"drilling and examinations are reported to indicate
75,000,000 tons or more . . . ". Based on the areal
exposures shown in figure 8, estimated reserves of
limestone (exclusive of quality ) are about 550,000 tons
90
California Division of Mines and Geology
Bull 197
per foot of depth for the main body and 100,000 tons
per foot of depth for the small southern mass. Until
average thicknesses are determined for each body,
however, total reserves cannot be accurately estimat-
ed. Even so, total reserves at the main body are cer-
tainly large and may well be 50 million tons or more.
The smaller body to the south, if structurally uncom-
plicated, would have an average thickness of about 50
feet and total reserves of 5 million tons. It is thought
that the limestone from the entire deposit might aver-
age 90% or more CaC03 and thus may be a future
source of cement raw material. Specific reserves of
sugar rock are much smaller than total limestone re-
serves but cannot be determined without careful drill-
ing and sampling. In 1962, the owner reported having
a 7- to 10-year supply of limestone blocked out as a
result of shallow drilling in the quarry area.
Other reference: Franke, 1935, p. 425.
Lopez Canyon deposits. SE corner sec. 36, T. 30
S., R. 1 3 E., M. D., and vicinity, 8 miles east of San Luis
Obispo; San Luis Obispo 1 5-minute quadrangle. Own-
ership: Not determined; probably U.S. Forest Service
land (1965).
Limestone and dolomite have been mentioned by
several investigators to occur along the course of
Lopez Canyon on both the southwest and northeast
walls. These carbonate rocks occur as beds, lenses, and
concretions commonly associated with siliceous and
clay shales of the Monterey Formation of Miocene
age. The beds are confined to the lower part of that
formation and apparently comprise a stratigraphic in-
terval having a maximum thickness of 300 feet (Fair-
banks, 1904, p. 4) . According to Laizure ( 1925, p. 523),
the main limestone sequence, which is about 100 feet
thick and dips 45° SW into the ridge, is prominently
exposed in Fern Canyon where it joins Lopez Canyon.
Here, the strata consist of dolomitic limestone and
limy dolomite which are thinly interbedded with cal-
careous, dolomitic, and siliceous shales (Oliver E.
Bowen, 1962, oral communication). The carbonate
rocks generally are brown to dark gray, bituminous,
fine grained, dense, hard, laminated, siliceous, and ar-
gillaceous. Weathered surfaces bleach to a light yel-
lowish tan or gray. Four samples of typical carbonate
rock were collected from the Fern Canyon section
(SE cor. sec. 36) by Oliver E. Bowen and analyzed by
Pittsburgh Testing Laboratories in 1959. The analy-
ses, given below in percent by weight, show the
material to be impure dolomite of variable composi-
tion.
Simple
SiO,
Fe/h
CjO
Lopez 1
54.25%
1.67%
<
IK4IW
11 W,
Lopez 2
33.67
0.96
3.48
22.90
8.42
041
Lopez !..
II 82
0.83
9.33
25.40
15.98
0.13
Lopez 4
5 15
0.67
8.54
29.80
12.00
0.29
Limestone from Lopez Canyon reportedly was used
as a source of lime in the 1880s (Irelan, 1888, p. 532),
but there is no record of production. In 1924, Peter
Rodriguez and S. J. Rhyne located three claims near
the mouth of Fern Canyon and erected a small kiln,
but only a small amount of lime was burned (Laizure,
l°25,p. 522). Because the carbonate deposits of Lopez
Canyon are impure and of variable chemistry, they do
not appear to be of future interest.
Other references: Aubury, 1906, p. 80; Franke, 1935, p. 425; Logan, 1947,
p. 305.
Morgan deposit. Location: Sec. 36 T. 32 S., R. 14
E., M.D., 5 miles northeast of Nipomo and 8 or 9 miles
east of Arroyo Grande; Nipomo 1 5-minute quadran-
gle. Ownership: Not determined.
Dark-gray limestone is exposed in isolated patches
30 to 40 feet wide over a considerable distance along
the tops of the ridges near Loma Pelona (Aubury,
1906, p. 80). The limestone probably is part of the
Monterey Formation which underlies the southwest
half of sec. 36. Apparently, the deposit was worked to
a minor extent around 1900 as a source of lime rock.
A kiln is situated in adjacent sec. 35.
Navajo deposit. S'/2 sec. 28 and N'/2 sec. 33, T. 29
S., R. 16 E., M. D., 20 miles east of Santa Margarita and
7 miles northwest of Pozo; Pozo 1 5-minute quadran-
gle. Ownership: Trinidad Mining Company (c/o Karl
and Feree Pierce, Morro Bay) owns eight unpatented
claims (Navajo 1 to 8) (1963).
The Navajo deposit consists of several westward
trending lenses of Sur Series (?) limestone set as pend-
ants in granitic rock. Although exploratory and assess-
ment work has been fairly extensive, there has been no
commercial production. The largest mass is half a mile
long by a maximum of 600 feet wide. Its east end lies
at the summit of hill 2805 near the SE cor. sec. 28. To
the southwest, in N'/2 NE1/ sec. 33, there is a smaller
body about a quarter of a mile long and a maximum
of 300 feet wide. A much smaller lens lies due east at
the crest of hill 2707, and a few minor patches of
limestone are exposed nearby to the west. Internal
structures (bedding?) in the larger bodies generally
strike N 80° E and dip about 30° N, but there are some
variations in attitude. Dikes and sills of decomposed
granite pervade the limestone and may amount to 20%
of the lenses.
The limestone is white to blue gray, medium to
coarse crystalline, locally siliceous and sometimes
blotchy or banded. Chemical analyses of 11 samples
(table 19) showed an average of 51.82% CaO, 1.73%
MgO, and 2.42% Si02. Dolomite rock was not recog-
nized in the field but may be present locally.
Development work, done mainly about 1959, con-
sists of extensive cuts, a few test pits, an assessment
tunnel, and some shallow stripping. Some shallow
drilling is reported to have been done in the early
1960s, but there was no activity in May 1963 when the
deposit was visited by this writer. Limestone reserves,
excluding 20% for granitic dikes, are estimated to be
60,000 tons per foot of depth at the main mass and
1978
I i\u siom in 1 111 coasi Ranges
91
18,000 tons per foot of depth at the southwest lens.
Assuming the lenses persist at depth, total reserves
recoverable by open pit mining may be on the order
of 15 to 20 million tons.
Table 19. Chemical analyses of Novojo limestone deposit.
La Panza
Ronge,
Son Luis
Obispo County.
Sample
00
MgO
Fcfi,
\l.4K
SiOi
p*o,
Trinidad 1
S3.6W6
0.83%
0.0119!
i 0.66%
1.34%
0.195%
Trinidad 2
49.70
3.16
0.029
1.81
2.88
0.067
Trinidad i .
52.00
0.83
0.014
0.98
3.25
0.345
Trinidad 4
51.60
1.62
0.120
0.64
2.55
0.042
Trinidad 5 .
50.70
2.17
0.037
0.89
2.65
0.089
Trinidad 6
53.80
0.71
0.027
0.44
1.45
0.088
Trinidad "
52.20
0.69
0.063
0.65
3.80
0.056
Trinidad 8
53.80
0.54
0.180
1.07
1 44
0.057
Trinidad 9
51.00
3.60
0.030
0.74
0.66
0.138
Trinidad 10
52.50
1.04
0.043
0.50
3.46
Nil
Trinidad 1 1
49.10
3.88
0.054
0.64
4.11
0.058
Samples collected by Oliver F. Bowcn. April 1959: 1-8 from main lens, 9 from
southeast lens, 10-1 1 from southwest lens; analyzed by Pittsburgh Test-
ing Laboratory June 11, 1959.
Based on the chemistry of the limestone, limited
reserves, and distance from transportation facilities
(30 miles by road to rail head at Santa Margarita), the
Navajo deposit appears to be useful, principally as an
emergency source of cement raw material.
Newsom deposit. Sec. 23 or 24, T. 32 S., R. 13 E.,
M I) , 2 to 3 miles east of Arroyo Grande; Arroyo
Grande 1 5-minute quadrangle. Ownership: Not deter-
mined.
A flat-lying bed of soft, clayey limestone (marl), 5
to 6 feet thick, is reported in the canyon near Newsom
Springs (Aubury, 1906, p. 80; Logan, 1947, p. 306).
The material was burned for lime at a nearby kiln
around 1900 or earlier. The deposit apparently is too
small to be of economic interest.
Nipomo deposit. Location: Near Nipomo. Own-
ership: Not determined.
A large body of soft, marly limestone in the vicinity
of Nipomo is mentioned by Irelan (1888, p. 532) . The
deposit was developed as a source of lime in the 1880s.
The location and nature of this occurrence are not
known.
Oak Flat deposit. Location: Not determined; re-
ported west of Paso Robles. Ownership: Not deter-
mined (1962).
According to Angel (1890, p. 584), a bed of lime-
stone at Oak Flat was developed extensively as a
source of lime burned locally in the late 1880s. Al-
though Oak Flat is not identified on recent maps, it is
believed to refer to the low-lying granitic terrane 3 to
5 miles northwest of Paso Robles (Jennings, 1958;
Durham, 1968). The exact location of the deposit is
not known.
Other references- Aubury, 1906, p. 80; Logon, 1947, p. 306.
Santa Margarita deposit. Location: Possibly sec. 5,
6 or 8, T. 29 S , R 13 F., M D, 2 to 3 miles north of
Santa Margarita; San Luis Obispo 1 5-minute quadran-
gle. Ownership: Not determined; probably Santa
Margarita Land and Cattle Company, 311 California
Street, San Francisco (1966).
Brown crystalline limestone, exposed over a width
of 20 feet and length of 1 mile, is reported north of
Santa Margarita (Logan, 1919, p. 689). The limestone
is said to trend northwest. Detailed geologic mapping
by this writer in the area north of Santa Margarita
failed to reveal such a limestone deposit, although beds
of sandy algal limestone and fine-grained dolomite are
interbedded with punky calcareous mudstone and
shale of the Monterey Formation. These rocks do not
appear to be of economic interest, and none have been
quarried.
Other references: Loizure, 1925, p. 522; Logon, 1947, p. 306.
Santa Margarita Ranch deposit. Location: Near
center sec. 28, T. 29 S., R. 13 E. (proj ), M.D., 1% mile
southeast of Santa Margarita; San Luis Obispo 1 5-
minute quadrangle. Ownership: Santa Margarita
Land and Cattle Company, 31 1 California Street, San
Francisco (1966).
Massive beds of sandy coquina and oyster shell reefs
as much as 10 or more feet thick are interbedded with
friable sandstone of the Santa Margarita Formation
(upper Miocene). The coquina is impure, consisting
of broken shell debris mixed with quartz-feldspar
sand. Entire shells of the giant oyster (Ostrea titan)
comprise the purer but less extensive reefs. The depos-
it is developed by a narrow bench cut about 200 feet
long with a maximum face of 12 feet, together with
several smaller prospect cuts and trenches in the im-
mediate vicinity. To the southwest and just below the
main cut is a concrete foundation — possibly the foun-
dation of a pre-existing crusher or other processing
facility. There is no record of commercial production,
although at least 1,000 tons of shells and sand were
quarried at the main cut. The deposit apparently was
prospected by Comar Shell Company (Los Angeles),
whose lease on the property terminated about 1928
(1966, W. D. Reis, Santa Margarita Land and Cattle
Co., oral communication).
Similar deposits of sandy coquina and oyster shell
reefs occur at various horizons within the Santa Mar-
garita Formation, elsewhere near Santa Margarita,
and in other parts of the upper Salinas Valley.
Tassajara deposit. Location: Sees. 21 and 28, T. 29
S., R. 12 E., M.D., 4'/j miles west of Santa Margarita;
San Luis Obispo 1 5-minute quadrangle. Ownership:
U.S. Forest Service land (1969).
S. Aumaier of San Luis Obispo located three claims
on a deposit of white, coarse-crystalline calcite prior
to 1925. The calcite occurs as veins, the largest being
12 to 14 feet wide, and was reported traceable over the
length of two claims (Laizure, 1925, p. 522). One
northwest-trending vein exposed by a small prospect
pit near N'/4 cor. sec. 28 is reported to be 3 to 5 feet
thick and to consist of large, partly deformed crystals
7 — 89454
92
California Division of Mines and Geology
Bull 197
of calcite as much as 4 inches long (Randy Tomer,
1969, personal communication). The veins occur in a
sequence of Lower Cretaceous shale and sandstone,
which is bordered to the south by serpentine. An anal-
ysis of the calcite by Smith, Emery, and Company
shows 54.24% CaO, 0.42% MgO, 0.45% Si02, 0.19%
A120„ 0.85% Fe20„ 0.80% Mn,04, and 43.40% igni-
tion loss.
Other than short open cuts made prior to 1925, the
deposit is undeveloped. The calcite veins are closely
approached by roads up Tassajara Creek and along the
crest of the Santa Lucia Range.
Other references: Franke, 1935, p. 426; Logan, 1947, p. 306.
SANTA YNEZ DISTRICT (C-6)
The Santa Ynez district (plate lC) encompasses the
limestone and dolomite deposits of southern Santa
Barbara and southwestern Ventura Counties includ-
ing the southeast end of the San Rafael Mountains of
the Coast Ranges and the Santa Ynez Mountains of the
Transverse Ranges. Although the deposits lie in two
separate geomorphic provinces (Jenkins, 1938), they
are geologically related and therefore are discussed
together.
The deposits are situated in hilly to mountainous
terrain that rises from sea level to maximum eleva-
tions of 6,828 feet in the San Rafael Mountains and
4,618 feet in the Santa Ynez Mountains. The west-
ward-flowing Santa Ynez River divides the two
ranges and provides access into much of the higher
region. Major transportation and access routes include
the Southern Pacific Railroad, which follows the
coastline, and four state and federal highways. Ocean
shipping facilities are limited. Santa Barbara and Ven-
tura, with 1970 populations of 69,538 and 58,000, re-
spectively, are the largest cities in the district. The
nearest major marketing center is Los Angeles, 70
miles by road to the east of the nearest limestone
deposit.
Virtually all of the limestone and dolomite deposits
of the Santa Ynez district belong to formations of
middle Eocene (Sierra Blanca Limestone) and Mio-
cene (basal Monterey Formation, Temblor Forma-
tion?) ages. The Sierra Blanca Limestone, lying at or
near the base of the Juncal Formation (or the equiva-
lent Anita Shale), is sporadically present throughout
the area. This unit is the only known source of high-
quality limestone in the district, the Sierra Blanca
deposit north of Santa Barbara being by far the larg-
est. Here, the limestone is bioclastic, dense, hard, and
apparently of sufficient purity and size to be used for
cement, lime, and other purposes. However, its
remote position in the San Rafael Wilderness Area in
the rugged San Rafael Mountains has forestalled any
development of the Sierra Blanca deposit. There ap-
pears to be more incentive at the present to retain the
deposit as part of a wilderness area rather than de-
velop it as a mineral resource. Other deposits of Sierra
Blanca Limestone are much smaller (thinner), less
pure (sandy), and principally of local interest.
Because the Sierra Blanca Limestone has such a dis-
tinct fossil fauna, it has been studied thoroughly (Nel-
son, 1925, p. 352-354; Keenan, 1932; Dibblee, 1950, p.
25-26; Walker, 1950a; Page et ai, 1951, p. 1745-1749;
Dibblee, 1966a, p. 20-21). Less is known about the
other carbonate deposits of the Santa Ynez district.
All but one or two of the remaining deposits appear
to belong to the basal part of the Monterey Formation
(also called Monterey Shale) or equivalent middle Mi-
ocene formations. Two of the deposits indicated as
limestone by others (Aubury, 1906, p. 80; Dibblee,
1950, p. 34-42, 79-81, plates 1-4) have been sampled
and shown to be dolomite. It is suspected that other
occurrences of Monterey "limestone" will prove to be
dolomite or dolomitic limestone when tested. One
possible exception is the Miguelito Canyon deposit —
tentatively described as Monterey Formation — which
apparently yielded limestone for sugar refining. Aside
from use as a local source of crushed rock, dolomite of
the Monterey Formation conceivably may be of suffi-
cient quality in some places to be used as a refractory
material. However, more exploration and testing
needs to be done to evaluate the deposits, which com-
monly are sandy or siliceous.
At least seven deposits have been utilized as sources
of lime and crushed rock in the Santa Ynez district.
About 100,000 tons of limestone from the San Migueli-
to deposit produced for lime, and a minor amount
apparently was produced at the Matilija Canyon area.
Perhaps as much as 2 million tons of crushed and
broken stone (including riprap, road base materials,
concrete aggregates, and filter rock) were obtained
from the Missile City, Bee Rock, El Jaro, Alisal, and
Nojoqui Canyon deposits. Production of limestone for
lime ceased many years ago, when reserves at San
Miguelito were depleted. On the other hand, produc-
tion of dolomite and limestone for crushed rock has
occurred sporadically according to need. Deposits that
may be of significant future interest, other than for
crushed rock uses, include 1) the Sierra Blanca lime-
stone deposit which has large reserves of good quality
material, and 2) various deposits which contain large
reserves of dolomite possibly adequate for refractory
or other special purposes.
The deposits of the Santa Ynez district are de-
scribed alphabetically below.
Alisal deposit. Location: Sec. 21 (proj.), T. 6 N.,
R. 3 1 W., S.B., nearly 1 mile southwest of Solvang; Los
Olivos 15-minute quadrangle. Ownership: Not deter-
mined.
Basal limestone of the Monterey Formation is ex-
posed along the south bank of the Santa Ynez River
where it extends west-northwest over a strike length
of 3,000 feet and dips steeply north. The deposit is
about 50 feet thick and consists of hard, light-gray,
algal limestone, the basal portion of which consists of
1978
I.IMI MOM l\ I III COASI K s
93
calcareous and tuffaceous, pebbly, fossiliferous sand-
stone (Dibblee, 1950, p. 81, plate 4).
The deposit is developed by a quarry at its east end
and w. is worked intermittently from 1928 to 1941. The
limestone was crushed to various sixes and used for
road construction (surfacing?) by Santa Barbara
County. No analyses are available, and the deposit
may be dolomitic.
Bee Rock deposit. Location: SW1/ sec. 3 1, T. 6 N.,
R. 29 W., S.B., 7'/, miles north of Naples and 18 miles
northwest of Santa Barbara; San Rafael Mountain 15-
minute quadrangle. Ow nership: Not determined.
Dense, massive, light-gray limestone, containing
several layers of chert, is exposed prominently at Bee
Rock 2 miles south of Cachuma Dam. The deposit dips
gently to the south and is truncated down dip by a
north branch of the Santa Ynez fault. The limestone
is a basal unit of the Monterey Formation (Miocene)
which locally rests on Matilija Sandstone(?) . A thin
overburden of siliceous shale overlies the limestone in
places. The maximum thickness of the limestone se-
quence is 200 feet (Dibblee, 1966a, p. 47, 89-90, plate
3; T.W. Dibblee, Jr., 1963, personal communication).
The deposit extends over a strike length of half a
mile, a maximum width of 900 feet, and a relief of
more than 500 feet. Based on topography, limestone
reserves above the base (1,800 feet elevation) of the
sheer cliff defining the south side of Bee Rock are
estimated to be about 6 million tons. Total reserves of
the deposit cannot be estimated, as the average thick-
ness is unknown. Although reserves are relatively
large, it is not known if sufficient limestone is avail-
able for cement manufacture. Further, the chemical
quality of the limestone is not known and needs to be
determined — particularly because carbonate rock of
the Monterey Formation is generally dolomitic and
siliceous.
The limestone was used in construction of the Ca-
chuma earth and rock fill dam, completed in 1953.
Apparently a large amount of limestone was used as
a rock blanket or riprap. The limestone came from a
quarry on the south side of Bee Rock, 2 miles south of
the dam.
El Jaro deposits (including Dibblee quarry). Lo-
cation: Sees. 19, 20, 28, 29, 30, and 33 (proj.), T. 6 N.,
R. 3 3 W., S.B., 6 to 8 miles southeast of Lompoc; Lom-
poc 1 5-minute quadrangle. Ownership: W. C. H. Dib-
blee (Rancho San Julian) (1950).
Gently folded carbonate beds at the base of the
Monterey Formation are exposed extensively on both
sides of El Jaro Creek, as shown by Dibblee (1950,
plate 3). According to Dibblee (p. 79), the carbonate
unit is a maximum of 1 50 feet thick and consists of 70
feet of "pure limestone" which grades downward into
"calcareous tuffaceous sandstone with local occur-
rences of conglomerate at the base". The carbonate
unit grades by interbedding into the overlying Monte-
rey shale. Actually, the rocks exposed along State
Highway 1 are largely dolomite as shown by the anal-
yses in table 20. Where sampled, the dolomite is gener-
ally brown to grayish brown and bituminous,
weathering to a light buff color. It is also hard, dense
to slightly vuggy, locally brecciated, and commonly
contains concentrations of replacement chert. The
beds are faintly laminated to massive, commonly be-
ing broken and contorted. The main deposits lie in S'/2
sees. 19, 20, and 28, and W/2 sec. 29. Dolomite reserves
may be large; more sampling, and perhaps drilling,
needs to be done to evaluate the quality and sizes of the
various deposits. It is possible that some of the dolo-
mite, if selectively quarried, may be of value as a re-
fractory material.
Table 20. Chemical analyses of carbonate rock (Monterey
Formation) from the El Jaro deposit, Santa Barbara County.
Simple SiO: Fe.O, AI.O, CaO \1g<) P.O.
l.J-1 6.48% 0.56% 0 83% 29 98% 17.89% 0.11%
LJ-2 6.03 0.55 0.94 28.84 19.07 0.05
LJ-3 1.86 0.62 1.71 30.02 19.88 0.14
LJ-4 1.89 0.29 0.58 30.59 20.18 0.22
LJ-5 3.53 0.62 0.51 30.49 19.46 0.12
LJ-6 3.70 0.18 1.96 29.65 19.51 0.28
LJ-7 • 2.33 0.70 1.12 53.14 0.22 0.05
Samples collected by Oliver F.. Bowen at intervals from south to north in road
cuts east of El jaro Creek in F.% of SE'/. sec 19 (proj ). T. 6 N., R. 33 W.
Samples LJ-1 to LJ-4 are from lower beds; LJ-5 and LJ-6 arc from middle
beds, and LJ-7 is from upper bed Most samples are bituminous, and some
contain small patches of chert Sample LJ-1 is brecciated Analyzed by
Abbot A Hanks, Inc., 1956
• Analysis questionable, as hand specimen retained is dolomite
One of the carbonate deposits east of El Jaro Creek
was worked intermittently from 1928 to 1944 through
a large quarry located in SW1/ sec. 20. According to
Dibblee (1950, p. 80), "the limestone here is about 40
feet thick, grading upward into brittle chertv shales.
About 1 5 feet of conglomerate occurs at the base of the
limestone". The beds dip north into the hill. Produc-
tion has been limited to crushed rock utilized for road
construction (surfacing) in the Lompoc area.
La Salle-Sloan Canyon deposits. Location: Ap-
pro*, sees. 11 and 12 (proj ), T. 6 N., R. 35 W., S B.,
3'/2 to 5 miles west-southwest of Lompoc; Point Ar-
guello 1 5-minute quadrangle. Ownership: U.S. Naval
Missile Facility (west half only).
Dibblee (1950, p. 79-80, plate 3) shows four elon-
gate exposures of limestone, each half a mile long or
less, that form a west-trending arcuate belt 2 miles
long within the Monterey Formation. The deposits
are crossed by La Salle Canyon on the west and Sloan
(San Pascual ?) Canyon on the east. The limestone
beds have a maximum thickness of 100 feet and dip
steeply north. The Tranquillon Yolcanics (agglomer-
ate) underlies the limestone unit, and shale of the
Monterey Formation overlies the unit. "The lime-
stone is similar to that of El Jaro Canyon, consisting
of pure limestone grading downw ard into calcareous
sandstone" (Dibblee, 1950, p. 80). As at the El Jaro
deposits, the carbonate rock at La Salle and Sloan Can-
94
California Division of Mines and Geology
Bull 197
yons is probably dolomitic. The deposits are un-
developed. Access is via the La Salle Canyon road.
Las Positas Ranch deposit. Location: 3 miles west
of Santa Barbara in "Veronica Valley". Ownership:
T. W. Moore, Santa Barbara (1925).
Coarsely crystalline limestone of yellowish color is
said to have been used for "cement" in construction of
the Santa Barbara Mission, but tests show the material
to be of no commercial value. The precise location of
this deposit is unknown and it is not mentioned by
Dibblee (1966a), who mapped the area in detail.
Other references-. Aubury, 1906, p. 80; Huguenin, 1917, p. 739; Tucker,
1925, p. 553.
Los Prietos deposit. Location: Sec. 1 1 (proj.), T. 5
N., R. 27 W., S.B., 8 miles north of Santa Barbara;
Gibraltar Dam 15-minute quadrangle. Ownership:
Not determined.
Logan (1947, p. 310) reports a deposit of limestone
south of the serpentine in which the Los Prietos mer-
cury mines are located. This prospect is probably the
same as the bed of hard, white, algal limestone that is
a maximum of 10 feet thick and occurs near the top of
the "Temblor" sandstone (middle Miocene). The
limestone, which is exposed south and west of Gibral-
tar Dam, is reported to be impure (Dibblee, 1966a, p.
,44). There is no known development.
Matilija Canyon deposits. Location: Sees. 22, 23,
24, and 25, T. 5 N., R. 24 W. and sec. 19, T. 5 N., R.
23 W., S.B., 514 to 8 miles west-northwest of Ojai;
Ventura 15-minute quadrangle. Ownership: Not de-
termined, but in Los Padres National Forest.
Several deposits of limestone have been reported
from both sides of Matilija Canyon under various
names (Argilla group of claims, Matilija claims, Ven-
tura Cement Company, and Ojai Cement Company).
Most, if not all, of these deposits consist of Sierra
Blanca Limestone, a prominent unit that is intermit-
tently present at or near the base of the Juncal Forma-
tion (middle Eocene). The distribution of the Sierra
Blanca Limestone deposit in the Matilija Canyon area
is not known in detail but is shown in a general way
by Merrill ( 1954) . He shows the limestone to occur in
two places at the base of the Juncal, which rests on
Cretaceous strata. The thicknesses of the limestone
deposits are not known; but the largest is over a mile
long, extending westward along the projected north
boundary of sec. 25, T. 5 N., R. 24 W. The other
deposit lies about a mile to the west in S'/2 sec. 22 and
is about two-thirds of a mile long. Both deposits lie in
extremely brushy, rugged terrain on the north flank
of the Santa Ynez Mountains within a mile of the road
up Matilija Canyon. Presumably, these are the princi-
pal deposits described in the past as potential sources
of cement rock. Another limestone deposit is suggest-
ed north of Matilija Creek in sec. 19 — possibly along
the trend of the basal Juncal — and also may be Sierra
Blanca Limestone.
Because of difficult access, it may be years before
the economic potential of these deposits is known.
Some data from past exploration indicate that the
deposits are siliceous and of value principally for ce-
ment. However, the sizes of the deposits are unknown.
The various efforts to develop the limestone deposits
in Matilija Canyon are summarized below.
Argilla claims — located by E. Duryea in sees. 23 and
24. The claims cover a "massive bed of limestone on
the south side of canon, striking east and west, dipping
south" (Huguenin, 1917, p. 762). It has been sampled
frequently, an average reported analysis being
16.015% Si02, 5.32% A120, and Fe20„ 42.63% CaO,
1.119% MgO, and 34.19% C02.
Matilija claims — 2 claims in sec. 19, T. 5 N., R. 23
W. An outcrop of hard blue limestone exposed on a
ridge crest north of Matilija Creek is reported to be 75
to 100 feet thick and half a mile long (Tucker and
Sampson, 1932, p. 266). The deposit is undeveloped
and of difficult access, being situated half a mile north
of Stingley's Hot Springs (site) in Matilija Canyon.
Ventura Cement Company — owns 400 acres of land
in sees. 22, 23, 26, and 27. A compact, fine-grained,
gray limestone with an east strike and steep southerly
dip is exposed in a main southwest tributary to Matili-
ja Canyon. The limestone is described as being "in at
least two strata, separated by 300 feet of shale. These
two strata are approximately 75 and 175 feet thick,
respectively" (Tucker and Sampson, 1932, p. 268).
The deposit can be traced to the west about half a mile.
All of the published analyses show the limestone to be
somewhat impure, with silica being especially high
(Huguenin, 1917, p. 762; Tucker and Sampson, 1932,
p. 268). Selected samples, however, reportedly run as
high as 97.86% CaC03. The company explored the
deposit with open cuts. Remains of an old kiln, appar-
ently used to burn lime many years ago, are reported
in the bottom of Matilija Canyon.
Ojai Cement Company — apparently investigated
the Sierra Blanca Limestone deposits in Matilija Can-
yon about 10 to 15 years ago (Oliver E. Bowen, 1964,
oral communication; based on a consulting report by
Frank Wicks). The deposit investigated was reported
to be a maximum of 60 feet thick. Associated calcare-
ous shale was believed to be blendable with the lime-
stone. Apparently there has been no development
work done following this preliminary investigation.
Other references: Tucker, 1925, p. 239-240; Logan, 1947, p. 348-349.
Missile City (Lind) deposit. Location: SE'/ sec.
19 and SW'/4 sec. 20 (proj.), T. 6 N., R. 34 W., S.B., 4
miles south-southwest of Lompoc; Lompoc 15-minute
quadrangle. Ownership: Missile City Rock Corpora-
tion, 2185 Huntington Drive, San Marino (1963).
Dolomite exposed on the north flank of La Tinta
Hill was first developed in the late 1950s when Missile
City Rock Corporation drilled and tested the material
as a source of crushed rock for concrete and base
materials.
1978
I imi niom- in nil- Coast Ranges
95
The deposit is believed to be the same as the J. C.
1 nui "limestone" deposit, which w.is sampled many
years ago and found to be too high in magnesia for use
in sugar refining (Huguenin, 1917, p. 739). Produc-
tion of dolomite began in I960, principally for con-
struction uses at the nearby U. S. Air Force and
missile facilities. After more than a million tons of
dolomite were produced, operations reportedly ceased
August 1, 1963. The quarry, referred to as the Lompoc
quarry by the present operator, was operated again
from 1964 through 1968 by Schmidt Construction,
Inc., P.O. Box 118, Camarillo, California — mainly for
the production of riprap (unpublished records).
The deposit consists of a sequence of poorly strati-
fied dolomite that constitutes a basal member of the
Monterey Formation (Miocene). T he dolomite is ex-
posed as a bold knoll (elevation 1,300 feet) on a north
spur of Fa Tinta Hill and also makes up much of the
debris in the adjacent landslides (T. W. Dibblee, Jr.,
1964, oral communication; Dibblee, 1950, plate 3). Al-
though the deposit was not visited bv this writer, a
composite sample (washed, crushed) from a finished-
product stockpile was obtained (collected by H. B.
Goldman, July 1962) for examination. T he sample in-
dicates that much of the dolomite is light buff to tan,
hard, dense, and commonly composed of algal (?) de-
bris. However, some of the dolomite is darker (gray,
grayish brown), slightly vuggy, or sandy. A composite
chemical analysis made by Matti Tavela and Fydia
Fofgren of the Division of Mines and Geology, 1963,
showed the following: 7.2% Si02, 0.80% Al20„ 0.36%
Fe,0„ 17.1% MgO, 30.3% CaO, 0.28% K20, 0.54%
P,Os, and 42.2% ignition loss. Variations in the types
of dolomite present are observable in the sample and
some of the dolomite may be of sufficient quality for
use as a refractory material. However, distribution
and reserves of the various kinds of dolomite are un-
known.
Most of the dolomite produced by Missile City Rock
Corporation apparently was taken from a hillside
quarry at the main exposures north of Fa Tinta Hill.
However, in mid- 1962 it was reported that the main
quarry was inactive and that dolomite was being pro-
duced from outcrops to the east (H.B.Goldman, 1964,
oral communication). In the early operations, each
quarry blast loosened about 40, 000 tons of rock, about
a month's supply. According to Bergstrom (1961, p.
101-105), the loose rock was bulldozed over a cliff to
the plant level, causing additional breakage. From the
talus storage pile the dolomite was transferred to a
grizzly and screen where minus ;;-inch rock was wast-
ed, the oversize being crushed and sent to a large surge
pile. Next, the rock was conveyed to a screening tower
(250-tons-per-hour capacity) for secondary crushing
and screening to six different sizes from 1 inches to
rock dust. T he various size fractions were blended as
necessary (including addition of river sand for con-
crete aggregate) to produce base materials and con-
crete and bituminous aggregates, most of which were
used at the Point Arguello missile facilities and Yan-
denberg Air Force Base. Considerable amounts of
larger sized rock also were sold for riprap, slope pro-
tection, and filter rock, some being shipped as far as
Fos Angeles.
Other references: Aubury, 1906, p. 80, Logan, 1947, p. 309; Dibblee,
1950, plate 3.
Mono Creek-Blue Canvon deposits. Focation:
Mainly NW'/4 and SE'/« T. 5 N., R. 26 W., SB., 7 miles
northeast of Santa Barbara; Gibraltar Dam 15-minute
and Carpenteria 7'/,-minute quadrangles. Ownership:
Not determined.
Detached masses of Sierra Blanca Fimestone are
exposed in two areas: 1) as an elongate belt extending
for 3 miles along the north wall of Blue Canyon, and
2) to the northwest on both limbs of the Mono syn-
cline which is traversed by Mono Creek. In both areas,
the limestone unconformably overlies Espada Shale
(Cretaceous) and is conformably overlain by the Jun-
cal Formation (middle Eocene). The distribution of
the limestone is shown by Walker ( 1950a, plate 1 ) and
Dibblee (1966a, plate 1). T he limestone is similar to
that at the Sierra Blanca deposit to the north, being
light gray to buff, hard, dense and massive. It consists
largely of bioclastic debris (algae, corals, foraminif-
era) but is not as pure as the deposits to the north.
Quartz sand is commonly present and chert pebbles
are found at the base of the unit. At Mono Creek the
limestone reportedly averages 12 feet thick, although
it attains a thickness of 35 to 40 feet at the southeast
end of the exposures. To the southeast, at Blue Can-
yon, the limestone is 10 to 50 feet thick, averaging 20
feet.
The only chemical analysis available was made from
a channel sample representing 35 to 40 feet of lime-
stone thickness at the southeast end of the Mono
Creek deposits. The analysis, made by Abbot A.
Hanks, Inc., shows 51.12% CaO, 1.36% MgO, 0.52%
Al20„ 0.45% Fe20„ and 4.76% Si02 (Walker, 1950a,
table 1).
Because the deposits have limited reserves of high
quality limestone and are remotely situated with re-
spect to markets, development is likely to be limited
to local use. The limestone is accessible over dirt roads
via Camuesa Canyon and Romero Saddle. There is no
known development to date.
Other reference: Poge et ol., 1951, p. 1745-1749.
Nojoqui Canyon deposit. Location: S1. sec. 25
(proj ), T. 6 N., R. 32 W., S.B., 3'/2 miles south of
Buellton; Fos Olivos 15-minute quadrangle. Owner-
ship: Live Oak Ranch, Buellton (1959).
A prominent exposure of Sierra Blanca Fimestone
(middle Eocene) occurs west of Nojoqui Creek and
the parallel U.S. Highway 101. The main part of the
deposit occupies the nose of an eastward-plunging an-
ticline but bifurcates, extending up both sides of the
canyon to the west where it pinches out in sec. 26.
Altogether, the limestone extends discontinuously (?)
96
California Division of Mines and Geology
Bill. 197
for 2 miles up the south side of the canyon. According
to Dibblee (1950, p. 25), "it consists of about 50 feet
of gray-white, hard, sandy, algal limestone." It rests
unconformably on the Jalama Formation (Creta-
ceous) . At one time the material was quarried for road
material (Dibblee, 1950, p. 25, 80, plate 4).
San Miguelito (Union Sugar) deposit. Location:
Possibly S'/j sec. 18 or N'/2 sec. 19 (proj.), T. 6 N., R.
34 W., S.B., 3'/, to 4 miles southwest of Lompoc; Lom-
poc 15-minute quadrangle. Ownership: C. S. Larsen,
Lompoc (1925).
On the north side of San Miguelito Canyon, five
small limestone deposits were worked to depletion by
Union Sugar Company from about 1900 to 1919. Dur-
ing that interval, approximately 100,000 tons of lime-
stone were produced for use in sugar refining. The
material was hand cobbed and hauled 6 miles by wag-
on to Lompoc. Rail shipments were made from there
to Betteravia and, for a while, to Oxnard.
Broken and distorted beds of "pure white fossilifer-
ous limestone", which graded into "siliceous lime-
stone conglomerate", occurred as five distinct deposits
over 40 acres of land (Huguenin, 1917, p. 740). The
deposits apparently are depleted but may have been
part of what was mapped as Quaternary landslide
(Dibblee, 1950, plate 3). According to Dibblee (1964,
oral communication), the landslide debris north of
San Miguelito Creek is largely composed of "lime-
stone" which is typical of the basal part of the Monte-
rey Formation. That the landslide material was
worked is indicated by the remnants of several small
pits there. However, the identification of the Union
Sugar deposits is tentative, as available analyses show
the carbonate rock of the Monterey Formation to be
generally dolomitic.
Other references: Aubury, 1906, p. 81-82; Tucker, 1925, p. 553.
Sierra Blanca deposit. Location: SE1/ T. 7 N., R.
27 W., SW'/4 T. 7 N., R. 26 W., and N'/4 T. 6 N., R. 26
W., S.B., 15 to 17 miles north of Santa Barbara; San
Rafael Mountain and Gibraltar Dam 15-minute quad-
rangles. Ownership: Lies within Los Padres National
Forest (San Rafael Wilderness Area).
The Sierra Blanca limestone deposit is situated a
few miles south of Big Pine Mountain which, at 6,828
feet elevation, is the highest point in the San Rafael
Mountains. The deposit is exposed as an elongate belt
traversing elevations ranging from 3,100 to 4,900 feet.
Except where its western end is crossed by Forest
Service road, the limestone belt is nearly inaccessible.
Because of its remote location, the deposit remains
undeveloped although mapping and limited sampling
indicate large reserves of good quality limestone.
Around the turn of the century, the east end of the
deposit was examined near the Moraga Ranch as a
source of lithographic stone by the Loma Blanca Lith-
ographic Stone Company (Aubury, 1906, p. 80).
However, it was considered unsuitable for litho-
graphic use.
The limestone deposit is exposed as a continuous
belt that extends 5% miles southeastward from the
East Fork of Santa Cruz Creek (1 mile west of Big
Pine Mountain Road) to a point 1 mile west of Mono
Creek (see figure 9). It consists of a distinctive se-
quence of middle Eocene bioclastic limestone which
was named the Sierra Blanca Limestone by Nelson
(1925, p. 352-354). The Sierra Blanca Limestone also
is exposed 1 to 2 miles to the north along the Big Pine
Mountain road, but these deposits appear to be too
small to be of economic value. Locally, the carbonate
unit rests unconformably on Upper Cretaceous sedi-
mentary rocks and is overlain conformably by Eocene
shale and sandstone. The limestone unit dips moder-
ately to steeply northeast, although there may be local
variations due to folding and faulting.
Much of the limestone is pale buff, or, less often,
grayish buff to brownish gray, and weathers to a very
light gray. Typically, it is dense, hard, poorly bedded,
and breaks with an uneven fracture. It is composed of
fine to coarse organic debris derived from algae,
Foraminifera, and various megascopic shell forms. Oc-
casional impure, sandy horizons are reported, particu-
larly in the upper part of the unit (Keenan, 1932, p.
65). The bulk of the unit is relatively pure, as indicat-
ed by the chemical analyses in table 21. The limestone
is of adequate quality for cement manufacture and if
analyses are representative, some of the limestone ap-
pears to be sufficiently pure for use in lime and chemi-
cal manufacture.
Table
21. Chemical analyses of limestone from the
Sierra
Blanca deposit, Santa Barbara
County.
Al,0,+
Simple
ao
\lgi)
Fe/h
SiOs
PsP,
M.
f KEENAN '
930 K
50.73%
3.00% 1.80%
i <m
trace
930 P
54.32
0.71
0.94
0.96
trace
930
55.33
0.32
0.56
0.24
trace
930 R
54.88
0.66
0.66
0.42
none
G.
W. WALKER !
0.37 +
5
53.07
1.14
0.33
2.01
ND
CALIFORNIA DIVISION OF MINES AND GEOLOGY
3
SB 1
54.31
0.58
0.48
1 04
0.06%
SB 2
54.47
0.66
0.46
0.76
0.08
SB 3
54.31
0.53
0.56
0.94
0.06
SB 4
54.60
0.62
0.52
0.48
0.05
SB 5
54.77
0.54
0.32
0.56
0.08
SB 6
54.70
0.59
0.34
0.44
0.08
SB 7
54.90
0.52
0.32
0.28
0.06
SB 8
54.70
0.46
0.44
0.62
I) 1)5
1 Samples collected by M F Keenan, September 1930, from bank of Indian
Creek and represent the middle 55 feet of the stratigraphic thickness of
the 22 5-foot-thick limestone unit. Analy/.ed by Leslie Larrieu, Los Ange-
les (Keenan, 1932, p. 70).
2 Composite grab sample from Big Pine Mountain road cuts representing 70
to KO feet of stratigraphic thickness Analyzed by P T. Bee, Abbot A
Hanks, Inc., San Francisco (Walker, l°50a, p. 5).
3 Grab samples collected at about 40-foot intervals from west to cast along Big
Pine Mountain road by Oliver E. Bowen, California Division of Mines
and Geology. Analyzed by Abbot A. Hanks, Inc., San Francisco, 1°5?.
ND = Not done.
1978
I IMI MOM l\ I 111 COASI K \\<.l S
97
Limestone reserves are not known, either for the
total deposit or for any part of it. Total reserves obvi-
ous!) are large but cannot be calculated without
knowledge of the average thickness of the limestone
unit. The thickest part is reported to be 225 feet at
Indian Creek (Keenan, 1932, p. 65). Just east of the Big
Pine Mountain road, the most accessible part of the
deposit, the thickness probably exceeds 70 to 80 feet
(Walker, 1950a, p. 5) and reserves mav be several mil-
lion tons or more. Large reserves also may exist at
"Sierra Blanca Mountain" where the limestone is
boldly exposed. The limestone unit pinches out l'/2
miles southeast of there.
Because of transportation and access difficulties, it
may be a long time before the limestone is of economic
interest. At the present time, the west end of the
deposit is about 35 miles by road from the nearest
railhead and even farther from port facilities. I he-
nearest paved road, at Mono Public Camp, is 18.3
miles from the limestone deposit.
Other references: Huguenin, 1917, p. 739; Nelson, 1925, p. 352-354;
Logan, 1947, p. 310, Page el ol., 1951, p. 1745-1749; Gower el a/., 1966,
p. A25-A26.
6828'
Big Pme Mm
5"
\
?
N
Location Mop
1f>c
X
\
34 37 30
c
r
\
id
3 Miles
Figure 9. Map of Sierra Blanca Limestone, Santa Borbara County.
98
California Division of Mines and Geology
Bull. 197
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26, p. 2-39.
1978
Limi s roNE i\ 1 111 Coasi Ranges
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100
California Division of Mines and Geology
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1978
I.imisiom in mi Coast K woks
101
Index to
All known deposits are listed alphabetically. When
a deposit is known by more than one name, each addi-
tional name is also listed alphabetically and cross-refe-
renced to the name by which the deposit is generally
best known. For example, the reader looking for Agri-
cultural Lime and Compost Company is directed to
San Francisco Bay Shell.
Deposits described in the text can be located in the
text alphabetically under the district (see Contents for
district organization). T he deposits shown on the in-
dex map (plate 1) may be located on the map by dis-
trict and deposit numbers. The deposits are numbered
from north to south within three subprovinces or re-
gions (A, B, C).
A few deposits and prospects described in the text
are not located on plate 1. These deposits are indicated
by "ND" under deposit number.
Deposit District No.
A.S. and R C-l 8
Agricultural Lime and Compost Co. (see San
Francisco Bay Shell)
Alisal C-6 6
Almaden C-5 3
Argilla (see Matilija Canyon)
Aumaier and Rodriguez C-5 7
Baldy Ryon B-4 13
Barbee Ranch C-l 1
Bardin (see Hartnell Group)
Bordin Ronch C-l 11
Barnes Construction Co. (see Quail Creek)
Bay Shell Co. (see San Francisco Bay Shell)
Beck Dredging Co. (see Pioneer Shell Co. under San
Francisco Bay Shell)
Bee Rock C-6 8
Bender B-2 6
Benicia Cement Works B-2 9
Bernal B-4 5
Bethlehem Steel Co. (see Natividad)
Bird Canyon Ledge C-l 14
Bixby Creek C-3 2
Bixby Mountain C-3 3
Black Ronch B-l 1
Black Mountain (see Monte Bello Ridge; Permanente)
Bluerock Mountain C-l 31
Bond (see Monte Bello Ridge)
Bonnie Doon B-5 6
Bryan and Peorce-Twohy (Ideal Cement Co.) C-l 4
Burkhart and Teaford (see Marlife)
Burns Valley A-3 9
Buzzards Roost C-l 26
Cahill Ridge B-3 21
Calero Hill (see Rockaway)
Calero B-4 1 1
California Aggregates (Royce) B-3 14
California Chemical Corp. (see FMC Corp. under San
Francisco Bay Shell; Westvoco)
California Onyx Co. (see Wilbur Springs)
California Onyx Marble (see Tolenas Springs)
Capay Valley A-3 10
Coplotzi Quarry (see Pacific limestone Products Co.)
Carnegie B-3 9
Castro Volley B-4 15
Cement Hill B-2 2
Chalk Mountain A-3 4
Deposits
Deposit District No
Chalone Creek C-l ND
Clark Ranch B-4 ND
Coast Ridge C-3 9
Coleman Gulch (see Kohlmon Gulch)
Collins B-3 6
Cowell (see Cowell Home Ranch; CowellThompson
Creek; IXL; Lime Ridge; Limekiln Creek (near luciap
Cowell Home Ranch B-5 7
Cowell-Thompson Creek C-l 30
Crowe Ronch C-l ND
Daniels A-3 2
Davis and Jordan (see Cowell Home Ronch)
De Dero Quarry (see Pacific Limestone Products Co.)
Deming's Point B-2 5
Dibblee Quarry (see El Jaro)
Dicky's Quarry (see Cement Hill)
Douglas Ranch (see Los Gotos Lime Co.)
Dubost C-5 2
East Gabilan C-l 13
Eaton and Smith (see Lime Mountain)
El Jaro C-6 5
Ellis (see Los Gatos Lime Co.)
FMC Corp. (see Westvaco; San
Francisco Bay Shell)
Foshauer Ranch A-2 4
Fisher Ranch A-2 2
Flint-Steinbeck C-l 5
Fremont Peok C-l 12
Gallegos (see Mission Lime Marl)
Gambetta (see South Bay Dredging under San
Francisco Bay Shell)
Garner-Harris C-l 17
Guadalupe Creek B-4 9
Guadalupe Lime Co. (see Guadalupe Creek)
Guadalupe Portland Cement (see Son Jose
Cement Co.)
Guadalupe Reservoir B-4 10
Hackett A-l 5
Hamilton C-l 28
Hamilton Dolomite (see Westvaco)
Harkinson (see Oil Canyon)
Harlan (see Hamilton)
Harmony Hills C-l 6
Harris (see Garner-Harris; Palmtag-Horris)
Hartnell Group C-l 25
Haskins (see Westvaco)
Heoldsburg Marble Co B-l 3
Highway One B-3 13
Hilltop B-3 23
Hollister Dolomite (see Westvaco)
Holmes B-5 4
Hopper (see Lime Ridge)
Horse Canyon C-3 8
Huasna Area C-5 ND
IXL B-5 1
Ice Cream Grade B-5 2
Ideal Cement Co. (see San Francisco Bay Shell;
Rockaway; Bryan and Pearce-Twohy;
Ideal Cement Co. — San Juan Bautista Plont)
Ideal Cement Co. — San Juan Boutisto Plant C-l ND
Inorganic Chemicals Division, FMC Corp. (see FMC
Corp. under San
Francisco Boy Shell; Westvaco)
Inverness Park B-2 7
Jacoby Creek A-l 1
Jomesburg (see Lambert Ronch [Jomesburg])
Johnston A-l 7
ND — Location not determined
102
California Division of Mines and Geology
Bull. 197
Deposit District
Jolon C-3
Junipero Serra C-3
Kaiser Aluminum and Chemical Corp. (see Natividad;
Kaiser-Harris)
Kaiser Cement and Gypsum Corp. (see Permonente)
Kaiser-Harris C-l
Kalkar (see Pacific Limestone Products Co.)
Kennedy Road B-4
Kesseler (Kessler) C-5
Kohlman (Coleman) Gulch B-l
La Salle-Sloan C-6
Lambert Ranch A-3
Lambert Ranch (Jamesburg) C-3
Las Positas Ranch C-6
Lime Mountain C-5
Lime Ridge B-3
Limekiln Creek (near Chualar) C-3
Limekiln Creek (near Lucia) C-3
Lind (see Missile City)
Little Cholame C-4
Lockhart Tract (see Inverness Park)
Lompoc quarry (see Missile City)
Lone Star Cement Co. (see San Vicente Creek)
Lopez Canyon C-5
Los Gatos Lime Co B-4
Los Prietos C-6
Los Vergeles C-l
Lyndon .'. B-4
Manzanita A-3
Marble Peak (see Coast Ridge)
Marks Materials, Inc. (see Rockaway; Skyline)
Marlife C-2
Martin Ranch C-l
Matilija Canyon C-6
McBride Ranch A-l
McClellan Ranch A-l
McCray Ranch C-l
McLaughlin Lithographic Stone B-3
McPhail C-l
Melendy Ranch C-l
Middle Dam C-l
Middle Fork B-3
Miller Quarry (see Pacific Limestone Products Co.)
Mindego B-4
Missile City C-6
Mission Lime Marl B-3
Mitchell B-3
Mono Creek-Blue Canyon C-6
Monte Bello Ridge B-4
Monterey Lime Co. (see Bixby Creek)
Montford C-4
Moore A-l
Moraga Ranch (Loma Blanco Lithographic Stone Co.)
(see Sierra Blanco)
Morgan C-5
Mount Diablo Lime Marl Co. (see Lime Ridge)
Mount Diablo Quarries (see Lime Ridge)
Mount Harlan C-l
Napa Junction B-2
Natividad C-l
Navajo C-5
Nelson Creek C-4
Newsom C-5
Nipomo C-5
Nojoqui Canyon C-6
Noren B-2
Nye A-3
Oak Flat C-5
O'Hora Ranch (see Westvaco)
ND
10
20
4
9
6
2
3
5
ND
1
1
1
11
1
16
11
6
3
22
4
27
34
7
17
1
4
20
8
10
2
2
2
29
3
10
6
3
10
ND
7
8
1
ND
Deposit District No
Oil Canyon B-3 2
Ojai Cement Co. (see Matilija Canyon)
Old Mission Portland Cement Co. (see Ideal
Cement Co. — San Juan Bautista Plant)
Olema B-2 10
Orinda B-3 3
Ortley Shell Co. (see San Francisco Bay Shell)
Pacific Carrara Marble Co C-3 ND
Pacific Cement and Aggregates (see San Vicente Creek)
Pacific Limestone Products Co B-5 10
Pacific Portland Cement Co. (see Cement Hill;
Bryan and Pearce-Twohy; Ideal Cement Co. under
San Francisco Bay Shell; Ideal Cement Co. — San
Juan Bautista Plant)
Palm tag- Harris C-l 18
Parkhurst Ridge A-l 8
Patriquin (see Little Cholame)
Patterson Pass B-3 7
Peasley Gulch B-5 9
Permanente B-4 3
Picardo Ranch B-3 15
Pico Blanco C-3 6
Pilarcitos Creek B-3 22
Pioneer Shell Co. (see San Francisco Bay Shell)
Pleasanton B-3 10
Point Reyes (see Inverness Park)
Pope Valley B-l 5
Porter C-l 24
Power Line C-l 23
Purviance Ranch B-l 4
Quail Creek C-l 32
Quinan Ranch A-2 3
Reeves Northeast C-l 21
Rhodes and Jamieson (see Rockaway)
Richter (Rickter) A-l 4
Rockaway B-3 12
Rockland Lime and Lumber Co. (see Limekiln
Creek [near Lucia])
Royce (see California Aggregates)
Russian Kilns (see Olema)
San Benito Lime Co. (see Hamilton)
San Benito Quarries Co. (see Westvaco)
San Francisco Bay Shell (Ideal Cement; Pioneer Shell;
South Bay Dredging; Bay Shell) B-3
San Jose Cement Co B-4
Son Juan Bautista plant and quarry (see Ideal
Cement Co.)
San Mateo Creek B-3
San Miguelito C-6
San Vicente Creek B-5
Santo Cruz Lime Co. (see Son Vicente Creek)
Santa Cruz Portland Cement Co. (see San Vicente Creek)
Santa Margarita C-5
Santa Margarita Ranch C-5
Schmidt Construction, Inc. (see Missile City)
Sierra Blanco C-6
Sierra (Serra) Hill-Little Sur C-3
Sillacci Quarry (see Hartnell Group)
Skyline B-3
Smith Grade B-5
Snell Ranch B-4
South Bay Dredging Co. (see San Francisco
Bay Shell)
Spreckels Sugar Co. (see Hartnell group; Lime
Ridge; Bernal)
Spring Valley Ridge B-3 18
Standard Portland Cement Co. (see Napa Junction)
Stone Corral C-4 5
Sugarloaf C-l 9
11
ND
16
3
3
ND
5
1
4
24
5
6
ND — Location not determined
ND — Location not determined
1978
I mi s i ( i\i i\ 1 111 Coasi Ranges
103
Deposit District
Suisun Morble (see Cement Hill)
Tossojara C 3
Tassajara C-5
Thurber Quarry (see Pacific Limestone Products Co.)
Tolenas Springs B-2
Tomales Bay (see Inverness Park)
Tomoles Bay Shell B-2
Trinidad Mining Co. (see Navajo)
Trout Farm (see Inverness Park)
Tyson (see Skyline)
Underwood C-l
Union Sugar Co. (see San Miguelito)
Unnamed (near Abbott mine) A-3
Unnamed (near Chesbro Reservoir) B-4
Unnamed (near Geyserville) B-l
Unnamed (near Sunol) B-3
Upper Bird Creek C-l
Usal A-2
Ventura Cement Co. (see Matilijo Canyon)
Wagner's Pork B-5
34
8
14
2
19
15
1
Deposit District
Warwick Claims (see Wilbur Springs)
Webb and Mingus Calcite C-4
Webb and Mingus Dolomite C-4
Western Limestone Co. (see Holmes)
Westphal Ranch C I
Westvaco C-l
Westvaco Chemical Division, Food Machinery ond
Chemical Corp. (see FMC Corp. under San
Francisco Bay Shell; Westvaco)
Westvaco Chlorine Products Co. (see FMC Corp.
under San Francisco Bay Shell; Westvaco)
Wiedemann B-3
Winship {see Monte Bello Ridge)
White Woman A-l
Wide Awake A-3
Wilbur Springs A-3
Willow Creek (see Melendy Ranch)
Wright's Ranch B-4
ND — Location not determined
i
ND
33
19
9
7
5
12
A89454— 650 6-76 2M
CALIFORNIA DIVISION OF MINES AND GEOLOGY
THOMAS E GAY JR., ACTING STATE GEOLOGIST
STATE OF CALIFORNIA
THE RESOURCES AGENCY
DEPARTMENT OF CONSERVATION
CRYSTALLINE LIMESTONE AND DOLOMITE
DEPOSITS OF THE NORTHERN GABILAN RANGE
DISTRICT, MONTEREY AND SAN BENITO COUNTIES
CALIFORNIA
LIMESTONE. DOLOMITE IN COAST RANGES
BULLETIN 197 PLATE 2
36°40'
IBM.
ot uufwmv ne
R.5E R.6E
DEPOSITS^
8 A.S. and R
1 Barbee Ranch
11 Bardin Ranch
14 Bird Canyon Ledge
31 Bluerock Mountain
4 Bryan and Pearce-Twohy
(Ideal Cement)
26 Buzzards Roost
30 Cowell-Thompson Creek
13 East Gabilan
5 Flint- Steinbeck
12 Fremont Peak
17 Garner-Harris
28 Hamilton
6 Harmony Hills
25 Hartnell Group
20 Kaiser- Harris
2 Los Vergeles
16 Martin Ranch
22 McCray Ranch
27 McPhail
7 Middle Dam
29 Mount Harlan
10 Natividad (Kaiser)
18 Palmtag- Harris
24 Porter
23 Power Line
32 Quail Creek
21 Reeves Northeast
9 Sugarloaf
3 Underwood
15 Upper Bird Creek
19 Westvaco (Hollister)
33 Westphal Ranch
-^Described in text
2
— 'Sedimentary breccia and
conglomerate composed
portly of Sur Series Is.
CALIFORNIA DIVISION Of MINES AND GEOLOGY
THOMAS E GAV JR . ACTING STATE GEOLOGIST
WOE*. TO MAPS OF COAST DANCES REGIONS
LIMESTONE, DOLOMITE, AND SHELL DEPOSITS OF THE
COAST RANGES PROVINCE SHOWING REGIONS
(NORTHERN-A, CENTRALB, SOUTHERN - C)
AND DISTRICTS
EXPLANATION
DEPOSITS ACTIVE1' INACTIVE
Limestone
Limestone ond/or dolomit
(mued or undetermined
Dolomite
By E.W.Hart
1976
£«iensive oreos underloin by co'Donole rocks
'//////////'
Province and rerjionoKsubprovifKe) boundary
SCALE 1 1.000.000
MAPS A B AND C
District boundary
' 1966-1968 peood
BASE MAP BY U S GEOLOGICAL SURVEY
DEPOSITS AND DISTRICTS OF THE COAST RANGES PROVINCE
NORTHERN COAST RANGES IAI
Humboldt District. A-l
Mendocino District, A-2
t. Uul
2. Fuller Ranch
.V Quinan Ranch
4. Fatltauct Ranch
Clear bike District, A-3
I Nye
2. Danicli
3. Lambert Ranch
4. Chalk Mountain
5. Wilbur Spjmti
6. Man/anita
7. Wide Awake
8. Unnamed (near Abbott nil
V Durm Valley
10. Capay Valley
CENTRAL COAST RANGES IB)
Hciltlsburg District, U-l
I. Black Ranch
2 Unnamed (near G By Mr v! lie)
3. Healdshurg Marble
4. Putviancc Ram.li
5. Pope Valley
b. Kohlman Gulch
North li.iy District. B-2
I Tolcnai Sprln|l
2. Cement Hill
3, Napa Junction
4 Tomalei U.iy Shell DcpOlil
5 Dctning's I'oinl
ti. Ucndei
7 Inverncii Park
8. Noren
9 Bcnicia Cement Wotk»
10. Olema
3-5N-I
II
I9(?MN-21
S-1N-IW
I I-1N-IW
Ir.-lN-IW
2«.27..IN-2W
4,'t.JS-IW
23-2S-1W
29-45.5 b
1.I2.I8N-KWMI)
:i-inn.i.w
20-16N-SW
I2-I4N-7W
W',i 14N-SW
29-I4N-SW
31(71
s-SW
23 or 24-9 N 10 W
32-ION-5W
I3-8N-I3W
34- 3 N-9W
35- 3N-9W
33. 34-3 NOW
2K-2N-HW
S.iii Francisco ISjy District, 11-3
1 I inn' h.i,.-. (Cowcll)
2 Oil ( jnyon
4 MtiUuglilln
5. W ied cm. mn
Nil
7. Pittenon
8. Mitchell
10. Plnun'ion
11. San 1-r.inciKO Buy Shell
Dcpciiiu (Ideal.
Pioneer, South Rji i
12. Rockiway
13. Iliglmjy One
14. California Aggregate*
(Ken Royce)
15. PicutJ.. ILmeh
16. San Mateo Creek
17. Middle I oik
l«. Spring Valley Kidjtv
19. Unnamed (near Sunol)
20. Minion Lime Marl
21. C.ihill Ridge
22. Pilar.iios ( reek
23 Hilltop
24 Skyline
ii Glura District, 0-4
Mlmleijo
! Monie Hello Ridge
Permnnentc (Kulwr Ce
* (lypttim Corp. I
1 Kennedy Road
Bctn.il
>. Snell is 1 1 1. 1 1
'. Lot Guloi l.ime Co.
I. Guadalupe- Creek
i. GuaiLiiupe Reservoir
. Galen.
!. Wfighi % Ranch
7.K,I7,20-IN-IW-
IS.Ki-IN-ll:
I0.14.IS-IS-3W
32-3 S-4E
33.34-35-41]
4.5-4S-IE
Mainly IS .V 4S-1W A 4
2-lS-nW
IMS-6W
I I -IS-tiW
I 2-4S-OW
IH-4S-5W
1 9-4 S-SW
l9.29-4$-5W
22-4S-IE
JI-4S-IB
2.3-SS-5W. 33, 34-1S-SW
1 1-5S-SW
1 1 - J S-SW
12- SS-SW
7J8.I9-7S-3W; 22-7S-4W: I S-US-JWtMD
EH 7S-IW and SWW 7S-2W
17.IH-7S-2W
Location (aae-T-F
Beat)
3
San Vicente Creek (Pacific
22-IOS-3W
Cement at Aggregate))
4
Holmes
20-10S-2W
s
Smith Grade
25-L0S-3W
6
Bonnie Doon
25,26, 36-I0S-3
7
Cowcll Home Ranch
2,3,9,10,11.14-
IS-2W
8
Wagner'i Park
12 or 117-ltS-
W
9
Peasley Gulch
9-I1S-2W
10
Pacific Limestone Product!
I1.14-IIS-2W
Northern Santa Lucia Range District, C-3
2K-ir-S-*E-MI)
SOUTHERN COAST RANGES REGION (CI
Gabilan Range District, C-l
1 . Baibee Ranch
2. Lot Vergelei
3. Underwood
4 Bryan and Pearee-Twohy
(Ideal Cement)
5. Flint-Steinbeck
6 Harmony Mills
7. Middle Dam
8. A.S. and R.
9. Sugarloaf
10. Natividad (Kaiser Aluminum
23-9S-2S
15-1 IS-3F,;
Panoi lie Hills District, I -2
1. Mat life
9-13S-1E-MI)
N!4 I3S-3E; N1
13- I3S-4E
24-13S-4E
23-13S-4E
20-13S-5E
29- I3S-5E
28-I3S-SE
2S.36-I3S-3E
35.36-1 3S-3E;
33.34- 1 3S-4E;
3S.I3S-4E
36-13S-4E
3I-13S-SE
6- I4S-SE
28 to 33-13S-5 1
34-13S-SE
34.35- 1 3S-SE
2-I4S-5E
3.4-1 4S-5E
4-I4S-5E
4-14S-5E
4.S.7.8-14S-5E
7- 14S-4E
Mainly S'A 14!
14- I4S-5E
I3-I4S-5E; 18
23-14S-5E
22-I4S-5E
30- 14S-6E
2S.26-I4S-4E
7-ISS-5E
I0.1I-15S-5E
21.27.28-I5S-7
7. 18. 19.20,29. M4S-IIE-MD
Limekiln Cteek (neit
Chualar)
BUby Creek
Bixby Mountain
Sierra (Serra) Kill-
Lit lie Sur
Limber! Ranch
Pico Blanco
Ta xujara
Hone Canyon
Coatt Ridge (Marble
Peak)
Junlpero Serra
Limekiln Creek (near
Parkficld-Coalinga District, C-4
I Webb and Mingus Odette
2. Mont ford
3. Nelson Creek
4 Litile Cholamc tPatriquin)
5. Stone Corral
UMW UNIVKSfTY Of CJi w* ii
9,16-lBS-IE
Mainly 14.1 5,23. 25-18S-I E
M I8S-IE
17.I8.20-I8S-4E
25.36-I8S-IE. I,2.1I.12-19S-IE
29-1 9S-4E
3S-19S-5E; 2.3-20S-SE
195-2E; 20S-243E; 2IS-3A4E
I2-20S-I3E-MD
24-2IS-I4E
22.23.26-22S-I3E
3I-22S-I4E; 5.6-23S-14E
25,)6-24SI5E; 3I-24S-16E
Southern Santa Lucia Range District. C-5
1 . Lime Mountain
2 . Dubost
3. Almaden
4. Tauajani
5. Santa Marganla Ranch
6 Navajo
7. Aumaier and Rodriguez
8. Loper Canyon
9. Kcaaeler
10. Newton
1 1 Morgan
IS.16-26S-9E-MD
25-26S-9E. 30-26S-IOE
34,265-IOE
2I.28-29S-I2E
28-29S-13E
2HI.33-29S-I6E
30(7)-30S-l4E
36-30S-13E
•M6-31S-15F
23 or 24-32S-I3E
36-32S-14E
Sjntj Ynej District, C-6
I . Sierra lllanca
2 La SallevMoan
3. San Miguclito
4. Missile City
5. El Jiro
6 Aliul
7. Nojoqui Canyon
8. Bee Rock
9. Los Prieto»
10 Mono Creek-Blue Canyon
I I Malilija Canyon
Mainly SEV, 7N-27W and NW(4 oN-26W-SB
II.I2-6N-35W
18 or I9-6N-34W
I9.20-6N-34W
19,20.28.29.30.3 3-6N-33W
21-ON-3IW
2S-6N-32W
3I-6N-29W
MAP COMPILED 1969
THIS BOOK IS DUE ON THE LAST DATE
STAMPED BELOW
BOOKS REQUESTED BV ANOTHER BORROWER
ARE SUBJECT TO IMMEDIATE RECALL
RECEIVED
T
l*C - 7 2001
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