"A belt of limestone shows in several places on the west slope of the Santa Lucia range, not very far from the coast line. Its most northern outcrop is on Long Ridge, in Sec. 9 T. 18 S., R. 1 E. It runs in a southern direction to Sec. 36, T. 18 S., R. 1 E., and Sec. 31, T. 18 S., R. 2 E. Another conspicuous outcrop of limestone is found in Sec. 30, T. 19 S., R. 3 E. Farther down the coast, in the southern part of the county, the limestone forms very steep escarpments along the shore. Another belt of white, coarsely crystalline limestone is found at the foot of the west slope of the Gabilan range, especially east of Salinas. These limestone exposures are remnants of a thin bed overlying the granite."
"A belt of sandstone runs along the east slope of the Santa Lucia range, from Reliez Canon, T. 21 S., R. 7 E., in the northwesterly direction past Tassajara Springs into T. 19 S., R. 3 E. Near these springs, in Sec. 36, T. 19 S., R. 4 E., this sandstone, which is gray and olive in color, has been quarried and used for building the hotel. (See XIIIth Report, California State Mining Bureau, p. 636.) It is, however, too far from a railroad to be, as yet, of commercial importance."
"Monterey County, by Clarence A. Waring and Walter W. Bradley, Field Assistant. Field Work in September and November, 1914.
"Situated as it is, Monterey County offers inducements which have only been partially realized. Extending from the Pajaro River to the Sixth Standard Parallel south, with an excellent bay, and a railroad the full length of the Salinas River Valley, the county has little to stand in the way of development. The more fertile valley lands of the Salinas, San Lorenzo, San Antonio and Nacimiento rivers are practically all held as large 'ranchos' which would yield enormous revenue were they subdivided and subjected to intensive cultivation.
"The mineral resources have been little more than prospected, and within its boundaries lie mineral deposits which will contribute enormously to the future wealth of the state.
Location (of Monterey County)
"Monterey County borders the central coast of California and is separated from Santa Cruz County, to the north, by the Pajaro River. It adjoins San Luis Obispo County to the south, while to the east it is bordered by San Benito, Fresno, and Kings counties.
Topography (of Monterey County)
"The principal topographic features of Monterey County are the great central Salinas Valley drainage basin, paralleling the coast and emptying into Monterey Bay; the Santa Lucia Range along the western coast; and the southwestern slope of the Diablo Range on the eastern border.
Geology (of Monterey County)
"The geology of most of Monterey County is mapped and described in our Bulletin No. 69, on the Petroleum Industry of California. The Santa Lucia Range has a core of granitic rock. This is exposed in Santa Lucia Peak at an elevation of 5967 feet, and throughout the territory between Carmel River and Sur River, either along the coast or in the river cuts. Limestone and gneiss overlie the granite in places and make up Pico Blanco…, Ventana Cone…, Marble Peak…, Twin Peak and Con Peak…" Most of the area from Mill Creek southward to Three Peaks and bounded on the northeast by Nacimiento River is made up of Franciscan sandstone and shale with intrusions of serpentine. It is in the region of these serpentine intrusions, in the latter intrusive acid dikes, that the important mineral deposits of the Los Burros district are found. There is evidence of much faulting and the precipitous coast…follows a fault line. Monterey sandstone and conglomerate flank the mountains on the southwest side of Nacimiento River and dip towards the valley. Most of the older sediments exposed east of the Nacimiento consist of Monterey shale, which is considerably folded east of Jolon.
"Along the coast, resting unconformably on the granite and Franciscan rocks, are raised beach deposits…."
Mineral Resources (in Monterey County)
"Embracing an area of 3330 square miles and supporting a population of 24,146 (census of 1910), this stock-raising and agricultural county produced twelve mineral substances in 1913, valued at $178,679.
"The production table…shows the recorded output and value of the various mineral resources since 1893. The table does not show the output of single companies which produced brick, copper, coal, feldspar, fuller's earth, petroleum, quicksilver and sandstone."
Lime and Limestone (in Monterey County).
"The Mineral Earths Supply Company shipped several hundred tons of limestone during the year 1914 from north of King City.
"Deposits of considerable magnitude exist in the Santa Lucia mountains about three miles from the coast and extending roughly from Bixby's Creek southward to Cone Peak. Pico Blanco…is capped with limestone and isolated deposits occur overlying the Santa Lucia granite and interbedded with gneiss throughout the ranges southward. Marble Peak at the head of Lion Gulch contains considerable limestone and some marble, which dip about 35 NW. The deposits are interbedded with gneiss and faulting has broken them up to such an extent that a detailed examination would be necessary to determine their economic value. Deposits of possible economic importance occur on the ranch of Mr. John Little of Monterey, south of Point Sur; and on the 640-acre ranch of Mrs. C. L. Koch of Pacific Grove, in Sec. 36, T. 18 S., R. 1 E., which includes in part the deposit on Pico Blanco. A landing place suitable for shipping the latter deposit is said to exist north of Point Sur and 5 miles from Pico Blanco."
Area: 3,330 square miles
Population: 27,980 (1920 census)
Location: West-central portion of state, bordering on Pacific Ocean
"Monterey County produced eight mineral substances during the year 1919, having a total value of $133,504, as compared with the 1918 output worth $119,687. Its mineral resources include brick, clay, copper, coal, dolomite, feldspar, fuller's earth, gold, silver, gypsum, infusorial earth, limestone, mineral water, petroleum, quicksilver, glass-sand, sandstone, silver, and miscellaneous stone.
"In fortieth place, commercial production for 1919 was as follows:"
(Headings for the information below are: Substance, Amount, and Value.)
Dolomite, 8,280 tons, $29,120
Stone, miscellaneous, ---, $73,031
Other minerals,* ---, $43,353
(Total value) $148,504
(* Includes barytes, coal, feldspar, diatomaceous earth, salt, and silica.)
Dolomite (in Monterey County)
"Dolomite deposits in the foothills of the Gabilan Range in Monterey County near Natividad are more accessible and closer to the railroad than those on the other slope of the mountains in San Benito County, and have been worked on a larger scale. Production began in 1917 and continued at the rate of a few thousand tons annually up to the beginning of World War II. The manufacture of magnesium on this coast and the increase in production of steel during the war led to one large operation from which several hundred thousand tons of dolomite was produced. The only other operator of importance, and the only one to keep up regular production over a period of years has been a steel company which uses dolomite for lining basic open-hearth furnaces. Smaller tonnages, produced irregularly and used for terrazo, stucco dash, flux, lime, and CO2 gas, have come from several other deposits not lately active.
"Geological age and conditions are similar to those mentioned under San Benito County. The dolomite deposits and accompanying larger bodies of limestone are older than the pre-Franciscan granitic rock which has intruded and altered their lower beds, notably on Gabilan Peak, from which the limestone series takes its name. The limestone and dolomite beds, particularly on the lower slopes, as near Natividad, are remnants of what were probably much more extensive beds of the Sur series, described by Parker D. Trask (26, p. 134)* and John E. Allen (46, pp. 17-21).** The meager fossil remains found by Allen were insufficient to permit a determination of age of the limestone or even the nature of the organisms that built the deposit."
(* “Geology of the Point Sur Quadrangle, California,” University of California, Department of Geological Science Bulletin, vol. 16, pp. 119-186, 1926.)
(** Allen, John Eliot, "Geology of the San Juan Batista Quadrangle, California," California Div. Mines Bull. 133, pp. 9-75,1946.)
Limestone (and Marble in Monterey County)
"Limestone deposits are numerous in Monterey County and several have been worked in the past; but it has been years since commercial production was reported. The former operations have been described in early reports of the Division of Mines (Hanks, H. G. 84, p. 110; 86, pp. 29, 97; Irelan, W. Jr. 88, p. 410; Preston, E. B. 92, p. 260; Crawford, J. J. 94, p. 392; 96, p. 629; Aubury, L. E. 06, pp. 72, 73; Waring, C. A., 19, pp. 606-607; Laizure, C. McK 25, pp. 42-43; Fiedler, W. M. 44).* More recently, students of geology have examined and described parts of the county (Trask, P. D. 26, Reiche, p. 37).** Lime production stopped in 1910, and the last recorded output of limestone was in 1917. The early work was near Rockland Landing in T. 22 S., R. 4 E., where four kilns were operated in the eighties and early nineties, and lime was loaded onto steamers off-shore by means of an aerial tramway. Another early-day operation was in sec. 16, T. 18 S., R. 1 E., on Bixby Creek only 3 miles from the coast, where two or three kilns were operated from 1904-10. Farther inland, 6 to 12 miles northeast of Salinas, where dolomite has recently been quarried, considerable limestone was produced for use in beet-sugar factories.
(* (1) Henry G. Hanks, "Catalogue and Description of Minerals of California as far as known, with Special Reference to Those Having an Economic Value," California Mining Bureau Report 4, pp. 61-397, 1884. (2) Henry G. Hanks, "Building Stones and Building Materials in California," California Mining Bureau Report 6, pt. 1, pp. 16-34, 1886…California minerals, pp. 91-141. (3) William Irelan, Jr., Eighth Annual Report of the State Mineralogist for the Year Ending October 1, 1888, California Mining Bureau Report 8, 948 pp. illus., 1888. (4) E. B. Preston, "Monterey County," California Mining bureau Report 11, pp. 259-262, 1892. (5) J. J. Crawford, Twelfth Report of the State Mineralogist, California Mining Bureau Report 12, 541 pp., 1894. (6) J. J. Crawford, Thirteenth Report (Third Biennial) of the State Mineralogist for the Two Years Ending September 15, 1896, California Mining Bureau Report 13, 726 pp., 1896. (7) Lewis E. Aubury, The Structural and Industrial Materials of California, California Mining Bureau Bulletin 38, 412 pp., illus. 1906. (8) Clarence A. Waring and W. W. Bradley, "Monterey County," California Mining Bureau Report 15, pp. 595-615, 1919. (9) C. McK Laizure, San Francisco Field Division, "San Luis Obispo County," California Mining Bureau Report 21, pp. 499-538, 1925. (10) William Morris Fiedler, "Geology of the Jamesburg Quadrangle, Monterey County, California," California Division of Mines Report 40, pp. 177-250, map, 1944.)
(**Parker D. Trask, Geology of the Point Sur Quadrangle, California, University of California, Department of Geological Science Bulletin, vol. 16, pp. 119-186, 1926.
Parry Reiche, "Geology of the Lucia Quadrangle," University of California, Department of Geological Science Bulletin, vol. 24, pp. 115-168, map, 1937)
"The limestone deposits are part of the Sur series which includes also schists, quartzite, and gneiss and is the oldest group of rocks in the region. They are pre-Franciscan according to reports of studies of them in nearby areas. Most of the limestone bodies near the coast are small. The exceptions are the Pico Blanco deposit, 5 miles east of Point Sur, which has not been worked; and the deposits previously mentioned, near Rockland Landing and Bixby Landing, which have long been abandoned. The limestone has been altered to marble, which ranges in purity from almost pure CaCO3 to 70 percent or less CaCO3 with high percentage of diopside, feldspars, and other products of metamorphism. The grain size varies from fine to very coarse. In general, the beds of marble are usually not over 50 feet, and rarely 100 feet thick, and they are longest in a northwesterly direction, conforming to the structure of the enclosing rocks.
"The coastal ridges in which so many deposits occur over an airline distance of about 32 miles between Bixby Creek on the north and Mill Creek on the south, are rough and steep. One state road follows the coast the entire distance and there are no roads connecting with the railroad and main highway on the east. The only outlet for limestone from this region would be to the coast, where lime was once loaded directly on ships. Deposits in the eastern and northeastern part of the county are within reach of the railroad, and those on the slopes of Gabilan (Fremont) Peak are located so they will ultimately be available for use in the cement plant near San Juan Bautista. These latter deposits are similar to those described under San Benito County. The map shows location of most deposits in the county."