1978 



1 I\ll STONE IN THE COAST RANGES 



95 



The deposit is believed to be the same as the J. C. 

 Lind "limestone" deposit, which was sampled many 

 years ago and found to be too high in magnesia for use 

 in sugar refining (Huguenin, 1917, p. 739). Produc- 

 tion of dolomite began in 1960, principally for con- 

 struction uses at the nearbv U. S. Air Force and 

 missile facilities. After more than a million tons of 

 dolomite were produced, operations reportedly ceased 

 August 1, 1963. The quarry, referred to as the Lompoc 

 quarry by the present operator, was operated again 

 from 1964 through 1968 by Schmidt Construction, 

 Inc., P.O. Bo.x 118, Camarillo, California — mainly for 

 the production of riprap (unpublished records). 



The deposit consists of a sequence of poorlv strati- 

 fied dolomite that constitutes a basal member of the 

 Monterey Formation (Miocene). I'he dolomite is ex- 

 posed as a bold knoll (elevation 1,300 feet) on a north 

 spur of La Tinta Hill and also makes up much of the 

 debris in the adjacent landslides (T. W. Dibblee, Jr., 

 1964, oral communication; Dibblee, 1950, plate 3). Al- 

 though the deposit was not visited bv this writer, a 

 composite sample (washed, crushed) from a finished- 

 product stockpile was obtained (collected by H. B. 

 Goldman, July 1962) for examination. The sample in- 

 dicates that much of the dolomite is light buff to tan, 

 hard, dense, and commonly composed of algal (?) de- 

 bris. However, some of the dolomite is darker (gray, 

 grayish brown), slightly vuggy, or sandy. A composite 

 chemical analysis made by Matti Tavela and Lydia 

 Lofgren of the Division of Mines and Geology, 1963, 

 showed the following: 7.2% SiO^, 0.80% Al^O,', 0.36% 

 Fe,0„ 17.1% MgO, 30.3% CaO, 0.28% K,0, 0.54% 

 P,0,, and 42.2% ignition loss. \'ariations in the types 

 of dolomite present are observable in the sample and 

 some of the dolomite may be of sufficient quality for 

 use as a refractorv material. However, distribution 

 and reserves of the various kinds of dolomite are un- 

 known. 



Most of the dolomite produced by Missile (2ity Rock 

 Corporation apparently was taken from a hillside 

 quarry at the main exposures north of La Tinta Hill. 

 However, in mid-1962 it was reported that the main 

 quarry was inactive and that dolomite was being pro- 

 duced from outcrops to the east (H.B.Goldman, 1964, 

 oral commimication) . In the early operations, each 

 quarry blast loosened about 40,000 tons of rock, about 

 a month's supply. According to Bergstrom (1961, p. 

 101-105), the loose rock was bulldozed over a cliff to 

 the plant level, causing additional breakage. From the 

 talus storage pile the dolomite was transferred to a 

 grizzly and screen where minus 'i-inch rock was wast- 

 ed, the oversize being crushed and sent to a large surge 

 pile. Next, the rock was conveyed to a screening tower 

 (250-tons-per-hour capacity) for secondary crushing 

 and screening to six different sizes from 1'/, inches to 

 rock dust. The various size fractions uere blended as 

 necessary (including addition of river sand for con- 

 crete aggregate) to produce base materials and con- 

 crete and bituminous aggregates, most of which were 



used at the Point Arguello missile facilities and \'an- 

 denberg Air Force Base. Considerable amounts of 

 larger sized rock also were sold for riprap, slope pro- 

 tection, and filter rock, some being shipped as far as 

 Los Angeles. 



Other references: Aubury, 1906, p. 80; Logan, 1947, p. 309; Dibblee, 

 1950, plate 3. 



Mono Creek-Blue Canyon deposits. Location: 

 Mainly NVVy, and SE'/, V. 5 N., R. 26 \V., SB., 7 miles 

 northeast of Santa Barbara; Gibraltar Dam 15-minute 

 and Carpenteria 7'/2-niinute quadrangles. Ownership: 

 Not determined. 



Detached masses of Sierra Blanca Limestone are 

 exposed in tuo areas: 1) as an elongate belt extending 

 for 3 miles along the north wall of Blue Canyon, and 

 2) to the northwest on both limbs of the Mono syn- 

 cline which is traversed by Mono Creek. In both areas, 

 the limestone unconformably overlies Espada Shale 

 (Cretaceous) and is conformably overlain by the Jun- 

 cal Formation (middle Eocene). Fhe distribution of 

 the limestone is shown by Walker ( 1950a, plate 1 ) and 

 Dibblee (1966a, plate 1). The limestone is similar to 

 that at the Sierra Blanca deposit to the north, being 

 light gray to buff, hard, dense and massive. It consists 

 largely of bioclastic debris (algae, corals, foraminif- 

 era) but is not as pure as the deposits to the north, 

 (^artz sand is commonly present and chert pebbles 

 are found at the base of the unit. At Mono Creek the 

 limestone reportedly averages 12 feet thick, although 

 it attains a thickness of 35 to 40 feet at the southeast 

 end of the exposures. To the southeast, at Blue Can- 

 yon, the limestone is 10 to 50 feet thick, averaging 20 

 feet. 



'Fhe only chemical analysis available was made from 

 a channel sample representing 35 to 40 feet of lime- 

 stone thickness at the southeast end of the Mono 

 Creek deposits. The analysis, made by Abbot A. 

 Hanks, Inc., shows 5 1.12%' CaO, 1.36% MgO, 0.52% 

 AljO,, 0.45% Fe;0,, and 4.76% SiO, (Walker, 1950a, 

 table 1). 



Because the deposits have limited reserves of high 

 quality limestone and are remotely situated with re- 

 spect to markets, development is likely to be limited 

 to local use. Fhe limestone is accessible over dirt roads 

 via Camuesa (Canyon and Romero Saddle. I here is no 

 known development to date. 



Other referertce: Poge el al., 1951, p. 1745-1749. 



Nojoqui Canyon deposit. Location: S'/, sec. 25 

 (proj.), F. 6 N., R. 32 W., SB., 3'/, miles south of 

 Buellton; Los Olivos 15-minute quadrangle. Owner- 

 ship: Live Oak Ranch, Buellton (1959). 



A prominent exposure of Sierra Blanca Limestone 

 (middle Eocene) occurs west of Nojoqui Creek and 

 the parallel U.S. Highway 101. 'Fhe main part of the 

 deposit occupies the nose of an eastward-plunging an- 

 ticline but bifurcates, extending up both sides of the 

 canyon to the west where it pinches out in sec. 26. 

 Altogether, the limestone extends discontinuously(?) 



