94 



California Division of Mines and Geology 



Bull. 197 



yons is probably dolomitic. The deposits are un- 

 developed. Access is via the La Salle Canyon road. 



Las Positas Ranch deposit. Location: 3 miles west 

 of Santa Barbara in "\'eronica \'alley". Ownership: 

 T. W. Moore, Santa Barbara (1925). 



Coarsely crystalline limestone of yellowish color is 

 said to have been used for "cement" in construction of 

 the Santa Barbara Mission, but tests show the material 

 to be of no commercial value. The precise location of 

 this deposit is unknown and it is not mentioned by 

 Dibblee (1966a), who mapped the area in detail. 



Other references: Aubury, 1906. p. 80; Huguenin, 1917, p. 739; Tucker, 

 1925, p. 553. 



Los Prietos deposit. Location: Sec. 1 1 (proj.), T. 5 

 N., R. 27 VV., S.B., 8 miles north of Santa Barbara; 

 Gibraltar Dam l.vminute quadrangle. Ownership: 

 Not determined. 



Logan (1947, p. l\Q) reports a deposit of limestone 

 south of the serpentine in which the Los Prietos mer- 

 cury mines are located. This prospect is probably the 

 same as the bed of hard, white, algal limestone that is 

 a maximum of 10 feet thick and occurs near the top of 

 the "Temblor" sandstone (middle Miocene). The 

 limestone, which is exposed south and west of Gibral- 

 tar Dam, is reported to be impure (Dibblee, 1966a, p. 

 ,44). There is no known development. 



Matilija Canyon deposits. Location: Sees. 22, 2.3, 

 24, and 2S, T. 5 N., R. 24 W. and sec. 19, T. .5 N., R. 

 23 W., S.B., S^/i to 8 miles west-northwest of Ojai; 

 \'entura 1.5-minute quadrangle. Ownership: Not de- 

 termined, but in Los Padres National Forest. 



Several deposits of limestone have been reported 

 from both sides of Matilija Canyon under various 

 names (Argilla group of claims, Matilija claims, \'en- 

 tura Cement Company, and Ojai Cement Company). 

 Most, if not all, of these deposits consist of Sierra 

 Blanca Limestone, a prominent unit that is intermit- 

 tently present at or near the base of the juncal Forma- 

 tion (middle Eocene). The distribution of the Sierra 

 Blanca Limestone deposit in the Matilija Canyon area 

 is not known in detail but is shown in a general way 

 by Merrill ( 1954) . He shows the limestone to occur in 

 two places at the base of the Juncal, which rests on 

 Cretaceous strata. The thicknesses of the limestone 

 deposits are not known; but the largest is over a mile 

 long, extending westward along the projected north 

 boundary of sec. 25, T. 5 N., R. 24 W. The other 

 deposit lies about a mile to the west in S'/j sec. 22 and 

 is about two-thirds of a mile long. Both deposits lie in 

 extremely brushy, rugged terrain on the north flank 

 of the Santa Ynez Mountains within a mile of the road 

 up Matilija Canyon. Presumably, these are the princi- 

 pal deposits described in the past as potential sources 

 of cement rock. Another limestone deposit is suggest- 

 ed north of Matilija Creek in sec. 19 — possibly along 

 the trend of the basal Juncal — and also may be Sierra 

 Blanca Limestone. 



Because of difficult access, it may be years before 

 the economic potential of these deposits is known. 

 Some data from past exploration indicate that the 

 deposits are siliceous and of value principally for ce- 

 ment. However, the sizes of the deposits are unknown. 

 The various efforts to develop the limestone deposits 

 in Matilija Canyon are summarized below. 



Argilla claims — located by E. Duryea in sees. 23 and 

 24. The claims cover a "massive bed of limestone on 

 the south side of canon, striking east and west, dipping 

 south" (Huguenin, 1917, p. 762). It has been sampled 

 frequently, an average reported analysis being 

 16.015% SiOj, 5.32% AljO, and Fe^O,, 42.63% CaO, 

 1.119% MgO, and 34.19% CO^. 



Matilija claims — 2 claims in sec. 19, T. 5 N., R. 23 

 W. An outcrop of hard blue limestone exposed on a 

 ridge crest north of Matilija Creek is reported to be 75 

 to 100 feet thick and half a mile long (Tucker and 

 Sampson, 1932, p. 266). The deposit is undeveloped 

 and of difficult access, being situated half a mile north 

 of Stingley's Hot Springs (site) in Matilija Canyon. 



Ventura Cement Company — owns 400 acres of land 

 in sees. 22, 23, 26, and 27. A compact, fine-grained, 

 gray limestone with an east strike and steep southerly 

 dip is exposed in a main southwest tributary to Matili- 

 ja Canyon. The limestone is described as being "in at 

 least two strata, separated by 300 feet of shale. These 

 two strata are approximately 75 and 175 feet thick, 

 respectively" (Tucker and Sampson, 1932, p. 268). 

 The deposit can be traced to the west about half a mile. 

 All of the published analyses show the limestone to be 

 somewhat impure, with silica being especially high 

 (Huguenin, 1917, p. 762; Tucker and Sampson, 1932, 

 p. 268). Selected samples, however, reportedly run as 

 high as 97.86% CaCO,. The company explored the 

 deposit with open cuts. Remains of an old kiln, appar- 

 ently used to burn lime many years ago, are reported 

 in the bottom of Matilija Canyon. 



Ojai Cement Company — apparently investigated 

 the Sierra Blanca Limestone deposits in Matilija Can- 

 yon about 10 to 15 years ago (Oliver E. Bowen, 1964, 

 oral communication; based on a consulting report by 

 Frank Wicks). The deposit investigated was reported 

 to be a maximum of 60 feet thick. Associated calcare- 

 ous shale was believed to be blendable with the lime- 

 stone. Apparently there has been no development 

 work done following this preliminary investigation. 



Other references: Tucker, 1925, p. 239-240; Logon, 1947, p. 348-349. 



Missile City (Lind) deposit. Location: SE'X sec. 

 19 and SW'/, sec. 20 (proj), T. 6 N., R. 34 W., S.B., 4 

 miles south-southwest of Lompoc; Lompoc 15-minute 

 quadrangle. Ownership: Missile City Rock Corpora- 

 tion, 2185 Huntington Drive, San Marino (1963). 



Dolomite exposed on the north flank of La Tinta 

 Hill was first developed in the late 1950s when Missile 

 City Rock Corporation drilled and tested the material 

 as a source of crushed rock for concrete and base 

 materials. 



