1978 



Limestone in the Coast Ranges 



63 



Although exposures are poor and scattered, lime- 

 stone reserves appear to be no more than lOO.OOO 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'/ 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 l.'i-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 NE'X sec. 20 

 and NEy; 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 .')0,000 tons of 

 limestone. Some limestone and associated granite 

 probablv were produced in recent years from the low- 

 er Sillacci (Spreckels) quarry in NE'/, 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 

 carefully and warrant future consideration. 



Other references: Aubury, 1906, p. 73; Bowen ond Gray, 1959, p. 37; 

 Hon, 1966b, p. 59. 



Ideal Cement Company — San Juan Bautista 

 plant. Location: SE'/, 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 utiliz.ed 

 in the manufacture of cement has been obtained from 

 several properties in San Benito County, including 

 the Barbee Ranch, Bryan and Pearce-Twohy, Elint- 

 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 Cabilan in Monterey 

 County. For deposit descriptions, the reader is re- 

 ferred to the above-named properties. 



The San Juan Bautista plant utili/x's about 220,000 

 tons of limestone and other raw materials per year 

 plus 40,000 to60,000 tonsof 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: Aobury,1906, p. 184; Bradley and Logon, 1919, p. 626-630; 

 Logon, 1947, p. 276-277; Bowen and Groy, 1959, p. 23, 25; Bowen and 

 Gray, 1962, pt. 1, p. 7, and pt. 2, p. 4-5. 



Kaiser-Harris deposit. Location: W'/z sec. 3 and 

 E'/j 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'X cor. sec. 4, and others 

 may be present. Other deleterious features include 



•The plant ceased operations in 1973, apparently due to the high cost of 

 newly required pollution control equipment The plant uas subsequently 

 disinantled 



