1P78 



l.iMi sroNF. IN inE Coast Ranges 



57 



limestone is worked by benching at ^0- to .^O-fooi in- 

 vervals. After preliminary crushing and screening at 

 the i]uarries. the hmestonc is trucked about 6 miles to 

 the compan\- plant (see ideal Clement (!]ompany, San 

 Juan Bautista plant). At one time rail facilities con- 

 nected the plant with the deposit. 



Buzzard's Roost deposit. Location: E'/^ sec. 14, 

 r. 14 S., R. S E., M.D., 9V, miles south of Hollister; 

 Gonzales l.vminute quadrangle. Ownership: S. H. 

 Cowell Foundation, 2 Market Street, San Francisco, 

 and possibl\- others (1962). 



Bold, craggy outcrops of carbonate rock are exposed 

 at and near the summit of a 2645-foot peak, locally 

 knov^n 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 Dempster (unpublished mapping shown by Jennings 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, 19.^8). 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. 1 7 S., R. 7 E. (Gonzales 1 5- 

 minute quadrangle) in Monterey County 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 Creek deposit. Location: N'/j 

 sec. 30, r. 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, 188S, 

 p. 488). The property was also operated in the 189()s 

 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 (iray ( 1959, p. 37) to be a sheetlike mass that dips 

 steeply north. It is exposed on steep terram 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 he 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; Loizure, 1926, p. 237; Logon, 

 1947, p. 276. 



Crowe Raneh deposits. Limestone and dolomite 

 deposits, mentioned by Logan (1947, p. 274, 278) as 

 part of the Cassie Crowe holdings east of F"remont 

 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 Gabilan deposit. Location: SW'/i sec. 36 

 (proj.), r. 13 S., R. 4 E., M.D., 1 mile east and slightly 

 south of Fremont 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 (-ement 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 mi.xed lime- 

 stone and dolomite. Bowen and Gray further describe 

 the deposit as follows: 



"As seen in plon, the limestone mass overoges obout 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 moss has been penetrated by several hundred 

 feet of odtts, 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 on 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 reosonoble recovery depth) total approximately 16,000,000 

 tons. Substontial additional tonnage coutd 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 Gobilon 

 deposit, Monterey County (after Bowen and Gray, 1959, p. 31). 



Oxide #7 #7 #7 *4 #7 #rf »^ 



CaO 55.42% H.42% 54.73% 54.4}% .W.37% 54.}.?% 54.02% 



MgO 0.41 0.92 0.41 0.5} 0.45 0.48 0.99 



SiOj 0.24 0.94 1.52 0.86 0.86 0.92 0.82 



Fe,0, 0.20 0.14 0.}2 0.11 0.08 O.ll 0.1} 



Al,0, 0.10 0.14 0.}4 0.29 26 0.17 0.1} 



K;0 0.0} 0.02 0.06 ND ND ND ND 



Na,0 0.04 0.0} 0,02 ND ND ND ND 



P,0, ND ND ND 0.06 0.0} 0.02 0.02 



Ignition loss 



(chieny CO,) .... 4}.72 4}. 5} 4}. 18 ND ND ND ND 



ND = not done. 



Samples 1-3 were analyixd by Ideal Cement Co.; samples 4-7. by Abbot A. 

 Hanks, Inc. 



