so 



California Division of Mines and Geology 



Bull. 197 



Table 10. Chemical analyses of selected limestone samples. Pacific Limestone Products Company deposits, Santa Cruz County. 



Description 



Ignition 

 Simple SiOi AlsOj FeM CaO MgO P^Os loss Total 



South quorry (NVi cor. sec. 14-11S-2W) 



Coarse-cryslallinc, blue-gray limestone with small lensoid Kal-1 



patches of fine-grained material 

 White, coarse-crystalline limestone with 50% bands of fine- Kal-2 



grained, quartzose limestone. 



North quarry (SWVi sec. ll-nS-2Wl 



Extremely coarse-crystalline, dove-gray to blue-gray lime- Kal-3 



stone. 

 Same as Kal-.f, but nearly white and with lenses of medium- Kal-4 



grained quartz "sand" 

 Fine- to coarse-crystalline, light-to dark-gray, impure lime- Kal-S 



stone. 



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: SWyi sec. 9, T. 

 1 1 S., R. 2 W., M.D. (proj.), 3 miles west-northwest of 

 Santa Cruz business district; Santa Cruz y'/j-minute 

 quadrangle. Ownership; Not determined. 



A small body of crystalline limestone associated 

 with schist and granodiorite is exposed in Peasley 

 Gulch 1% 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 .10 feet wide (Oliver E. Bowen, oral communi- 

 cation, 196.S). 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: 



Div So. CaO Mg() SiO. AI.O, Fe,0, P.O, 



Ign. 

 loss 



44-PE-l 55.25% 00.51% 0.55% 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% miles north-northeast of the 

 PCA cement plant and the adjacent town of Daven- 

 port; Ben Lomond 15-minute quadrangle. Ownership: 

 Pacific Cement and Aggregates Division, Lone Star 

 Cement Corporation, 400 Alabama Street, San Fran- 

 cisco (1968). 



The San V^icente Creek deposit was first developed 

 about 1900 by the Santa Cruz Lime Company, which 

 operated there for ."i or 6 years. They quarried lime- 

 stone on the west side of San \'icente 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 4.^0 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 dioritc, whose contact with the lime- 

 stone is exposed along the northwest and southeast 

 margins of the deposit (Branner er a/, 1909). Diorite 

 is reported to penetrate the limestone body locally as 



