SOUTHERN COAST RANGES REGION (C) 



The southern Coast Ranges region includes the 

 Coast Ranges south of Monterey Bay and the Santa 

 Ynez Mountains of the Transverse Ranges. The 

 deposits lie in Fresno, Monterey, San Benito, San Luis 

 Obispo, Santa Barbara, and \'entura Counties. The 

 crystalline limestone and dok)mite deposits in the 

 Frazier Mountain area, at the southeast end of the 

 Coast Ranges, and the various deposits of the Trans- 

 verse Ranges east of the Santa Ynez Mountains were 

 not part of this study and are not described herein. 



Topographically, the southern Coast Ranges consist 

 of a series of northwest-trending mountain ranges and 

 intervening valleys that separate the broad San Joa- 

 quin Valley from the Pacific Ocean. Included among 

 the principal mountain chains are all or portions of 

 the Santa Lucia, Gabilan, Diablo, Temblor, and La 

 Panza Ranges, and the San Rafael Mountains (plate 

 IC). At its southeast end, the Coast Ranges swing 

 eastward, merging with the Santa Ynez Mountains 

 and other east-trending Transverse Ranges. 



The region is moderately populated, with most of 

 the people residing in the Salinas-Monterey, Santa 

 Barbara-\'entura, and San Luis Obispo-Santa Maria 

 areas. The economy is based largely on agriculture, 

 petroleum, and mining. As the region is quite moun- 

 tainous, many of the carbonate deposits are of limited 

 accessibility. Principal transportation routes are con- 

 fined to the larger valleys and the less rugged coastal 

 areas, and few paved roads cross the mountain ranges. 

 The Southern Pacific Railroad connects the main cit- 

 ies with Los Angeles to the southeast (via the coast) 

 and with San Francisco to the northwest (via Salinas 

 \'alley). There are no major deep-water ports in the 

 region, although limited facilities are available at sev- 

 eral ports between Monterey Bay and X'entura. 



Historically, many deposits have been developed in 

 the southern Coast Ranges region. Beginning in the 

 1880s, perhaps 20 limestone deposits were developed 

 as sources of lime — mainly for local use although some 

 limestone was shipped elsewhere in the region. Lime- 

 stone for cement manufacture has been quarried since 

 1918 by Ideal Cement Company and its predecessors. 

 Raw and calcined dolomite has been quarried continu- 



ously since 1900 for refractory, chemical, and crushed 

 rock uses, as well as for the manufacture of magne- 

 sium metal during World War II. Limestone, dolo- 

 mite, and mixed carbonate rocks also have been used 

 extensively for crushed rock, agricultural, and decora- 

 tive purposes. 



Between 1966 and 1968, the active dolomite deposits 

 were the Natividad (Kaiser Aluminum and Chemical 

 Corp.) and Westvaco (FMC Corp.) deposits of the 

 northern Gabilan Range and the Missile City deposit 

 in the western Santa Ynez Mountains. During that 

 same period, limestone was quarried for cement 

 manufacture at the Bryan and Pearce- Twohy deposit 

 (Ideal Cement Company) in the Gabilan Range and 

 for beet-sugar refining at Lime Mountain (Eaton and 

 Smith) in the southern Santa Lucia Range. Total 

 limestone and dolomite produced in 1968 amounted to 

 about 907,000 tons. 



The southern Coast Ranges region contains the 

 largest reserves of limestone and dolomite of the Coast 

 Ranges province. The principal deposits consist of 

 crystalline limestone and dolomite of the metamor- 

 phosed Sur Series (pre-Cretaceous), fossiliferous and 

 bioclastic limestone of the Sierra Blanca Limestone 

 (Eocene) and \'aqueros Formation (lower Miocene), 

 and impure fine-grained dolomite of the Monterey 

 Formation (Miocene). Smaller or less pure carbonate 

 deposits consist of dense limestone uith chert, shell 

 beds, veins, marl, marble onyx travertine, and possibly 

 caliche that were formed from late Mesozoic(?) to 

 C^aternary time. 



In addition to the recently active deposits, the larg- 

 est limestone deposits include the Pico Blanco deposit 

 of the northern Santa Lucia Range and the Sierra 

 Blanca deposit of the Santa Ynez Range. The lack of 

 development at both of these deposits has been due to 

 poor accessibility and, more recently, to the attention 

 paid to the high recreational or wilderness values in 

 these areas. An abundance of good quality limestone 

 appears to be available at these deposits. Smaller 

 deposits of limestone and dolomite of potential value 

 exist in the Gabilan Range, northern and southern 

 Santa Lucia Range, La Panza Range, and Santa Ynez 

 Range. Carbonate deposits elsewhere in the region 



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