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Contra Costa County


  • Contra Costa County Mineral Industry (circa 1919) - Excerpt from California Mineral Production for 1919, Bulletin No. 88, by Walter W. Bradley, California State Mining Bureau, 1920, pp. 145.

    Area: 714 square miles.
    Population: 53,889 (1920 census)

    “Contra Costa, like Alameda County, lies on the eastern shores of San Francisco Bay, and is not commonly considered among the mineral-producing counties of the state. It stands nineteenth on the list in this respect, however, with an output valued at $1,395,558 for the calendar year 1919. Various structural materials make up the chief items, including brick, cement, limestone, and miscellaneous stone. Among the others are asbestos, clay, coal, gypsum, manganese, mineral water, and soapstone.

    “Commercial production for 1919 was as follows:”

    (Headings for the information below are: Substance, Amount, and Value.)

    Clay and clay products, ---, $193,340
    Stone, miscellaneous, ---, $275,309
    Other minerals,* ---, $926,909
    (Total value) $1,395,558

    (* Includes cement and mineral water.)

    Contra Costa County, 1916 Map, from California Mineral Production for 1919 (with County Maps), Bulletin No. 88, by Walter W. Bradley, California State Mining Bureau, San Francisco: California State Printing Office, 1920, pp. 187. Contra Costa County , 1916 Map
  • Contra Costa County Limestone Industry and Deposits (through 1947) - Excerpt from “Limestone in California,” by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "The first lime made in California after the American occupation was burned in the spring of 1851 near Pacheco by a name named Shreeve, at what was called the Mt. Diablo quarries, but no definite record of lime production in the county was kept before 1903. Lime production continued until 1915, coming from the plant of Henry Cowell Lime Company 3 miles east of south of Concord. Spreckels Sugar Company produced limestone from deposits 5 miles from Concord for use in their sugar refinery and for sale to Selby Smelter until they sold out in 1915 to the Cowell interests, who had gone into the Portland cement business. The cement plant has been in operation ever since at Cowell on Rancho Monte del Diablo, about 5 miles by road south of east of Concord. In later years, most of the limestone produced in the county has been used in this plant, which has been closed down during 1946.

    "The deposits are of Recent travertine, occurring in a number of shallow beds, 20 feet or more thick, covered only by a thin bed of clay. They are along the Monte Diablo fault zone. The stone is mostly compact, brown, and faintly banded, but in places bluish or white. Although not regarded originally as large, important, or particularly high grade, these deposits have continued to produce large quantities of stone that has proved satisfactory for cement making. The clay used in the plant occurs nearby.

    "The geology of only the western part of Contra Costa County has been systematically covered. Although the results of geologic work done in the Mount Diablo quadrangle for private clients have been published in part (Taff, J. A. 35; Clark, B. L. 35)* these give scanty notice to limestone deposits.

    (*Joseph A. Taff, "Geology of Mount Diablo," Geological Society of America Bulletin 46, pp. 1079-1100, 1 pl., 1 fig., 1935.)

    "In the part of the county covered by the Concord quadrangle and the northeast part of the San Francisco quadrangle, both included in the San Francisco Folio of the U. S. Geological Survey (Lawson, A. C. 14), a great deal of detailed field work was done by several classes of students in geology at the University of California. This resulted in probably much closer examination than would be expected in an area with few important mineral deposits. The results of this work, so far as limestone is concerned, was summarized in the following brief statements, quoted from the folio:

    (*Andrew Cowper Lawson, Description of the San Francisco District: Tamalpais, San Francisco, Concord, San Mateo and Hayward Quadrangles, U. S. Geological Survey Geological Atlas, San Francisco folio (no. 193), 24 pp., maps, 1914.)

    'A few thin lentils of limestone occur in the Cretaceous rocks, but they have no commercial value. There are also many lentils of impure ferruginous and phosphatic limestone in the bituminous shales and cherts of the Monterey group.'

    'In the Orinda and Siesta formations limestone lenses occur more or less persistently at several horizons, and similar beds of limestone are interstratified with the lavas of the Moraga formation. All these lenses are of lacustral formation and most of them are siliceous. The best that can be said of them as to their economic value is that some of them may prove to be of service for local use.'

    "All of these are Pliocene formations. The Orinda is the most extensive, extending from the southeast corner of Concord quadrangle in a northwesterly direction to Giant and Sobrante. It has a surface width of 2 to 4 miles. No limestone has been separately mapped in this formation. In the fresh water Siesta beds at their contact with the volcanics of the Moraga, a few of the larger limestone deposits were shown. The largest of these is less than 1 mile north of Wilcox in sec. 15, T. 1 S., R. 3 W. It has been mapped as half a mile long by 500 feet or more in width."

  • Contra Costa County Mines and Mineral Resources (circa 1958) - Excerpt from "Mines and Mineral Resources of Contra Costa County, California," California Journal of Mines and Geology, Vol. 54, No. 4, State of California, Department of Natural Resources, Division of Mines, San Francisco, California, October, 1958, pp. 501-583.) (Used with permission, California Department of Conservation, California Geological Survey.)

    Introduction to Contra Costa County

    "Contra Costa County is in the Coast Ranges of central California. Its shores touch the tidewater of northern San Francisco Bay, San Pablo Bay, Carquinez Strait, Suisun Bay and the delta waters of the Sacramento-San Joaquin River system. The county adjoins Berkeley and Oakland along their eastern borders and is 15 miles east of San Francisco by automobile via the San Francisco-Oakland Bay Bridge.

    "Contra Costa, meaning 'opposite coast,' was the name applied to the land across the Bay by the early settlers of San Francisco, though the name lost some of its significance when Alameda County was formed from the western part in 1853...."

    Geology (of Contra Costa County)

    "Contra Costa County lies in parts of two geomorphic provinces. The major portion of the county is in the Coast Ranges province, with a small portion of the eastern end within the Great Valley.

    "The oldest rocks in Contra Costa County are part of the Franciscan-Knoxville group of Jurassic-Cretaceous age. These are predominantly of marine sedimentary origin with lesser amounts of submarine volcanic and ultramafic intrusive rocks. Overlying this assemblage are marine and continental sedimentary rocks of Cretaceous and Tertiary age, and Tertiary volcanic rocks. Quaternary alluvial deposits overlap the Tertiary strata in the northern and eastern portion of the county...."

    Mines and Mineral Resources (of Contra Costa County)

    "The total recorded mineral production of Contra Costa County from 1894 to 1956 is $98,641,031. In addition, coal valued at $14,300,000 was mined from the Mount Diablo coal field between 1867 and 1882. An undetermined amount of mercury was produced prior to 1894.

    "Contra Costa County ranked twenty-second among the 58 counties of the state in value of mineral production during 1956. Mineral commodities produced that year were valued at $5,174,878 which was an all-time high for the county...."

  • Contra Costa County, California - Contra Costa County Rock Products (circa 1958) - Excerpts from "Mines and Mineral Resources of Contra Costa County, California," California Journal of Mines and Geology, Vol. 54, No. 4, State of California, Department of Natural Resources, Division of Mines, San Francisco, California, October, 1958, pp. 501-583.) (Used with permission, California Department of Conservation, California Geological Survey.)

    "Since 1946 the rock products industry has ranked first in quantity and value among mineral commodities produced in Contra Costa County. The classes of rock products discussed in this section are: (1) broken and crushed stone used primarily for riprap and fill in waterfront projects; (2) crushed rock* used mainly as road base; (3) sand and gravel used as bituminous and concrete aggregate; (4) specialty sands including foundry and glass; and (5) dimension stone.**

    (* Page 545 footnote: "In technical usage 'stone' is the term applied to material that has been quarried from larger masses of rock, whereas 'rock' is applied to material in place before it is broken and cut. In this report, however, the widely accepted usage of the term 'crushed rock' is retained for broken and crushed stone that is used primarily for road construction.")

    (** Please note: Not all of these mineral commodities will be presented here. (3) sand and gravel. and (4) specialty sands. will not be presented. In addition, the other sections listed above will not be presented in their entirety.)

    "Commercial production of crushed stone is obtained from the Jurassic-Cretaceous (?) Franciscan group metavolcanic rocks at Mount Diablo (two quarries); Franciscan group graywacke-type sandstone at Castro Point (one quarry); Pliocene Moraga volcanic rocks near Orinda (one quarry); and Tertiary sandstone at Pacheco and Walnut Creek (two quarries). Sand is obtained from sand dunes near Antioch (two pits) and from sandstone beds of the Domengine formation (Eocene) near Cowell (two quarries) and Antioch (one quarry). No alluvial gravel is mined in the county.

    Broken and Crushed Stone (in Contra Costa County)

    "Broken and crushed stone for use as riprap and fill is produced at only one locality in Contra Costa County, the Blake Bros. quarry in Richmond. Large stone, while always in demand in the San Francisco Bay area, is not readily obtainable in the County.

    Photo 3. Blake Brothers quarry at Point Richmond. Blake Brothers quarry at Point Richmond

    "Riprap consists of regular fragments of broken stone, which range in weight from 35 tons to less than 100 pounds. They are placed without mortar to provide protection from the erosive action of water. Riprap is used in river and harbor areas and to protect bridge abutments, dams, spillways, and railroad and highway embankments...."

    "Most rock outcrops in Contra Costa County are fractured, soft, thinly bedded or too light to yield stone suitable for riprap. There are few geologic formations in the county from which sound stone may be obtained. The principal formations are the sandstone of the Franciscan group and the volcanic flow rocks of the Moraga formation...."

    "The principal source of broken and crushed stone in the county is a 5 mile long, half- to mile-and-a-half wide, ridge of Franciscan sandstone, called Portero San Pablo, which borders on the bay in the city of Richmond. The usable sandstone beds range in thickness from 8 to 10 feet, dip approximately 50 to the southwest, and strike northwestward. Some thinner sandstone beds are interbedded with minor amounts of shale. No prominent joint system is evident in the quarries. This is the same strata from which stone is produced across the bay in Marin County at San Pedro point. In the past, several quarries were worked at various places in the same zone on this ridge (Laizure 1927, Hueguenin and Castello 1920).

    "Blake Bros. operate the one remaining quarry (circa 1958), near the Richmond-San Rafael bridge, to produce riprap and other sizes of crushed stone. The rock is quarried by using a coyote-hole method of primary blasting. Large blocks of rock are broken up by dynamite charges placed in a small adit driven through the face, with crosscut drifts run back of the quarry face at the level of the quarry floor. The charges are placed in the crosscuts and part way out in the adit. Adit and crosscuts are then completely backfilled and all charges detonated simultaneously.

    "Fragments too large to be handled by power shovels are broken by secondary drilling and blasting. Diesel shovels load end-dump trucks which haul to a feeder pit from which the stone is conveyed to a 6-inch grizzly. The plus 6-inch to 250 pound stone is removed and trucked to the rail or barge facilities. Stone over 250 pounds is placed directly on trucks in the quarry by shovels for delivery to the job.

    "Some large stone, up to 10 tons, is occasionally obtained at the Tunnel Rock Company quarry in the Berkeley Hills near Orinda. The quarry has been opened in the south limb of a syncline in the east-dipping red and black andesite and basalt flows of the Moraga formation. Two-thirds of the rock is free digging, though primary blasting is used occasionally. The quarry is worked in benches 14-26' high. Drilling is done with wagon drills. The smaller fragmented material is loaded in trucks by power shovel. The larger pieces are pushed aside and broken into smaller fragments by a shovel equipped with a 5 ton drop ball.

    Crushed Rock (in Contra Costa County)

    "Crushed rock used as bitiminous aggregate, road base, railroad ballast, and fill constituted 90 percent of the stone production for 1955. Most of the crushed rock is used as aggregate base in road construction; only a small portion is used as bituminous or concrete aggregate. The bulk of the materials used for this latter purpose are imported into the county from sand and gravel plants near Niles and Livermore in Alameda County, and Tracy in San Joaquin County. There are few places in the county where sound, hard, durable rock suitable for crushing for use in concrete or bituminous aggregate, crop out...."

    Photo 4. Sand bunkers, waste dump, and shale outcrops near Black Diamond mine. Sand bunkers, waste dump, and shale outcrops near Black Diamond mine

    Contra Costa County Dimension Stone

    "Sandstone was quarried from the Martinez formation (Eocene) before the turn of the century for use as building stone. In 1894 a production of 20,000 cubic feet valued at $7,500 was reported.

    "Stone used in the buildings in the city of Martinez and in the Napa State Hospital was obtained from two quarries near Martinez; the Franklin sandstone quarry, located 3 miles southwest of Martinez in Franklin Canyon and the Martinez quarry located three quarters of a mile southwest of that city. The sandstone occurs in beds ranging from 8 to 25 feet in thickness which strike northwest to dip about 45 northeastward. The stone is blue-gray; it is soft when quarried but hardens upon exposure.

    "Paving blocks reportedly were produced prior to 1890 at small quarries in the hills between Concord and Clayton-about 6 miles northwest of Mt. Diablo presumably from the metavolcanic rocks of the Franciscan group."

  • Contra Costa County Rock Products (circa 1958) - Excerpts from California Journal of Mines and Geology: Mines and Mineral Resources of Contra Costa County, California and Research in Mining and the Mineral Industries of California, Volume 54, Number 4, October 1958. (Used with permission, California Department of Conservation, California Geological Survey.) Below you will find extracts from the above book for the following headings:
    • The Mount Diablo Quarries near Pacheco
    • Rock Products (in Contra Costa County 1956)
    • Broken and Crushed Stone
    • Specialty Sand
    • Dimension Stone
    • Limestone
    • Dimension Stone 
    • The Mount Diablo Quarries near Pacheco*

      (* California Journal of Mines and Geology: Mines and Mineral Resources of Contra Costa County, California and Research in Mining and the Mineral Industries of California, Volume 54, Number 4, October 1958. October 1958, pgs. 527-529.)

      "The Mount Diablo quarries near Pacheco were the site of the first lime-making in California after the American occupation. This began in the spring of 1851 (Logan 1947) although no records of production previous to 1903 are available. The Henry Cowell Lime Company reported lime production from 1903 until 1915, excepting 1906 and 1908. The limestone was originally hauled from the quarries on Lime Ridge 3 miles southeast of Concord to Concord where the kiln was located. Later, four standard continuous kilns were installed immediately below the quarry."

      "The Sprecklels Sugar Company quarried travertine from pits located south of the Cowell quarries for many years previous to 1915. This stone was shipped to the sugar refinery at Crockett and to the Selby smelter. At the latter plant it was used as a flux for smelting gold, silver and lead ores. This property was purchased by Henry Cowell Lime and Cement Company in 1916."

      "The Mount Diablo Lime Marl Company produced travertine from 1924 to 1927 which was crushed for agricultural use. These operations were probably centered on Lime Ridge in section 7 where there are three discontinuous shallow pits."

      ""The limestone deposits are surficial masses of travertine of Quarternary age which originated from calcareous springs issuing along a fracture in the underlying sedimentary rocks of the Tejon formation (Eocene)...."

      "The central core of the travertine is pale blue in color, grading outward to a buff-colored stone. The weathered surface is whitish gray and the outer surface of the buff stone is frequently lined with a selvage of white chalk. The solid travertine exhibits faint banding and swirling...."

      "The travertine has been mined from an innumerable series of shallow cuts, pits and benches which frequently merge from one another. Many bench-cuts range from 5 to 50 feet high and are a quarter of a mile long. The largest pit is located about a mile south of the cement mill. It has a face about 200 feet high above the water level in the pit and extends for about half a mile laterally...."

    • Rock Products (in Contra Costa County 1956)*

      (* California Journal of Mines and Geology: Mines and Mineral Resources of Contra Costa County, California and Research in Mining and the Mineral Industries of California, Volume 54, Number 4, October 1958. October 1958, pgs. 545-561.)

      "Since 1946 the rock products industry has ranked first in quantity and value among mineral commodities produced in Contra Costa County." Following are the types of rock products discussed in the chapter of the publication: "(1) broken and crushed stone used primarily for riprap and fill in waterfront projects; (2) crushed rock used mainly as road base; (3) sand and gravel used as bituminous and concrete aggregate; (4) specialty sands including foundry and glass; and (5) dimension stone."

      The quarries mentioned are: (2) two quarries at Mt. Diablo for production of crushed stone; one quarry which produced graywacke-type sandstone at Castro Point; one quarry which produced Pliocene Moraga volcanic rocks near Orinda; two quarries which produced Tertiary sandstone at Pacheco and Walnut Creek. Antioch sand dunes provided sand from two pits. There were two sandstone beds of the Domengine formation (Eocene). Two quarries were located near Cowell and one quarry was located in Antioch.

    • Broken and Crushed Stone (in Contra Costa County)

      The only location in Contra Costa County in which broken and crushed stone, used as riprap and fill, was produced was the Blake Bros. quarry in Richmond, which was the one remaining quarry in 1956.

    • Specialty Sand (in Contra Costa County

      "Significant tonnages of foundry and glass sand have been obtained from a number of localities in Contra Costa County. The bulk of production came from two localities, the Nortonville-Somersville area and the Brentwood area, with output divided about equally between them...."

      "Antioch-Marchio District. About 3 miles east of Nortonville at the old Star coal mine, the Marchio Sand Co., is operating a quarry in the same geologic formation. The sandstone is predominantly white...."

      "Brentwood District. Near Brentwood, about 7 miles to the southeast of the Marchio quarry, the same belt of Domengine sandstone was worked for foundry and glass sand from 1920 - 1942...."

      "Cowell District. The Domengine sandstone is being worked by the Silver Sand Co. near Cowell.white to buff-colored (where iron stained) sandstones."

    • Dimension Stone (in Contra Costa County

      "Sandstone was quarried from the Martinez formation (Eocene) before the turn of the century for use as building stone. In 1894 a production of 20,000 cubic feet valued at $7,500 was reported.

      "Stone used in the buildings in the city of Martinez and in the Napa State Hospital was obtained from two quarries near Martine; the Franklin sandstone quarry, located 3 miles southwest of Martinez, in Franklin canyon and the Martinez quarry located three quarters of a mile southwest of that city..The stone is blue-gray; it is soft when quarried but hardens upon exposure.

      "Paving blocks reportedly were produced prior to 1890 at small quarries in the hills between Concord and Clayton - about 6 miles northwest of Mt. Diablo...."

    • Limestone (in Contra Costa County)*

      (* California Journal of Mines and Geology: Mines and Mineral Resources of Contra Costa County, California and Research in Mining and the Mineral Industries of California, Volume 54, Number 4, October 1958. October 1958, pg. 572.)

      1. Coates - small limestone quarry in Oil Canyon, 7 miles southwest of Antioch, adjoined the Harkinson deposit.
      2. The Cowell quarry owned by Henry Cowell Lime and Cement Co., 2 Market St., San Francisco, quarried "Discontinuous masses of travertine crop out over a considerable area on Lime Ridge. Stone is white, buff or pale blue in color. Used in pre-1900 era for manufacture of lime. Quarried 1908-46 for manufacture of cement." At the time of the report, the quarry was idle.
      3. Harkinson located "In Oil Canyon, 7 miles southwest of Antioch. Compact, amorphous, bluish-gray, fossiliferous limestone. Small shipment."
      4. Hopper, L. C. leased by Mt. Diablo Lime Marle Co. - deposit and plant in September 1946.
      5. Mt. Diablo Lime Marl Co. "Produced crushed limestone for agricultural use from deposit 5 miles northeast of Walnut Creek."
      6. An unnamed mine quarried "Fresh-water limestone lense outcrop, about half a mile long and 500 feet wide along contact between Siesta and Moraga formations of Pliocene."
      7. An unnamed mine quarried by L. R. & M. Ginochio (?), 123 Beede Way, in Antioch. "Three pits on west side of Lime Ridge. Extend from Treat Lane northwestward for mile."
    • Dimension Stone (in Contra Costa County)*

      (* California Journal of Mines and Geology: Mines and Mineral Resources of Contra Costa County, California and Research in Mining and the Mineral Industries of California, Volume 54, Number 4, October 1958. October 1958, pg. 583.)

      1. Franklin (owner not determined) was "inactive" at time of report. "Sandstone quarried in 1890's from Martinez formation for use as building stone."
      2. Martinez (owner not determined) was "inactive" at time of report. "Located three-fourths of a mile southwest of Martinez. Martinez sandstone used in Napa State Hospital in 1890's."
      3. McNears (owner not determined) was "inactive" at time of report. "Located on line of Southern Pacific RR between Martinez and Port Costa; sandstone used at Port Costa in 1890's."

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