LIMESTONE, DOLOMITE, AND SHELL RESOURCES OF THE 

 COAST RANGES PROVINCE, CALIFORNIA 



By Earl W. Hart 



INTRODUCTION 



This report includes a discussion of all of the known 

 limestone, dolomite, and shell deposits of the north- 

 west-trending Coast Ranges, except those of the Frazi- 

 er Mountain area at the southeast end of the ranges. 

 The carbonate deposits of the Santa Vnez: Mountains, 

 \K hich are part of the I ransverse Ranges, are included 

 \Kith the deposits of the Coast Ranges for convenience 

 (figure 1). 



The Coast Ranges carbonate province defined by 

 this report (figure 1 ) covers 30,000 square miles, near- 

 ly one-fifth of California. It extends southeasterly for 

 600 miles from the Oregon border to southwest Ven- 

 tura County and is at most 70 miles wide between the 

 Pacific Ocean and the Great \'alley. The area is not 

 only extensive, but its complex geologic history has 

 permitted a wide variety of carbonate deposits to de- 

 velop. To facilitate discussion of the deposits, the 

 Coast Ranges are subdivided somewhat arbitrarily 

 into three subprovinces or regions — northern Coast 

 Ranges (A), central Coast Ranges (B), and southern 

 Coast Ranges (C). Ihe deposits are discussed geo- 

 graphically from north to south by regions and by 

 districts within each region (Contents and figure 1). 

 Deposits within each district are discussed in alpha- 

 betical order. 



The deposits are located on the district maps by 

 number from north to south. The names of all depos- 

 its, including kn(jwn synonyms, are listed alphabeti- 

 cally in the Index to Deposits at the end of this report. 



Development and Production 



Approximately 100 carbonate deposits have been 

 productive in the Coast Ranges province. In addition, 

 many more undeveloped deposits have been cited in 

 the literature as possessing economic potential. Be- 

 cause of extensive changes in transportation, mining, 

 processing, and other economic factors over the years, 

 the majority of the deposits no longer arc of economic 

 interest as sources of industrial limestone and dolo- 

 mite. However, some of these deposits may be of local 

 value as sources of crushed stone or building stone or 

 may be useful in some other way. 



Total production of limestone, dolomite, and shells 

 in the Coast Ranges through 1968 approximates 169 

 million tons. Referring to table 1, it can be seen that 

 the central regicm has accounted for 86 percent of the 

 total production. The principal limestone reserves 

 and all of the dolomite reserves, however, are located 

 in the southern region although substantial reserves of 

 limestone and shells are available in the central region. 

 In the 1966-1968 period, there were 1.3 active commer- 

 cial producers of limestone, dolomite, and shells in the 

 Coast Ranges province. The average yearly produc- 

 tion of about 6 million tons was obtained from the 

 following 11 deposits (with designated districts): 

 Tolenas Springs (North Bay); San Francisco Bay 

 Shell and Rockaway (San Francisco Bay); Per- 

 manente (Santa Clara); San Vicente and Pacific Lime- 

 stone Products (Santa Cruz); Bryan and 

 Pearce-Twohy, Natividad, and VVestvaco (Gabilan 

 Range); Lime Mountain (Southern Santa Lucia); and 

 Missile City (Santa Ynez) (see plate 1). 



Table 1. Estimated total production of limestone, dolomite, and 

 shells for tfie Coast Ranges, by regions and formations tfirough 

 1968. 



Estimated 

 production 

 Formation and principal r<Kk types (1,000.000 tons) 



NORTHERN COAST RANGES (A) 



.Miscellaneous limestone Minor 



CENTRAL COAST RANGES |B) 



"Sur Series", crystalline limestone 34 



Franciscan Formation, limestone and associated chert 62.$ 



Quaternary travertine, calcareous tufa, caliche 13 



f^uaternary shells of San Francisco Bay 33 



Miscellaneous and undetermined 2.5 



Subtotal 145.0 



SOUTHERN COAST RANGES REGION (C) 



Sur Series, crystalline limestone 9 



Sur Series, crystalline dolomite 10.5 



\ aqueros Formation, limestone 1.5 



Monterey Formation, dolomite and dolomitic limestone 2 



Miscellaneous limestone and marl 1_ 



Subtotal 24.0 



Grand total 169.0 



