92 



California Division of Mines and Geology 



Bull. 197 



of calcite as much as 4 inches long (Randy Tomer, 

 1969, personal communication). The veins occur in a 

 sequence of Lower Cretaceous shale and sandstone, 

 which is bordered to the south by serpentine. An anal- 

 ysis of the calcite bv Smith, Emery, and Company 

 shows 54.24% CaO, 0.42% MgO, 0.4.5% SiO„ 0.19% 

 A1,0„ 0.85% Fe,0„ 0.80% Mn,0„ and 4.3.40% igni- 

 tion loss. 



Other than short open cuts made prior to 192 5, the 

 deposit is undeveloped. The calcite veins are closely 

 approached by roads up Tassajara Creek and along the 

 crest of the Santa Lucia Range. 



Other references: Franke, 1935, p. 426; Logon, 1947, p. 306. 



SANTA YNEZ DISTRICT (C-6) 



The Santa Ynez district (plate IC) encompasses the 

 limestone and dolomite deposits of southern Santa 

 Barbara and southwestern \'entura Counties includ- 

 ing the southeast end of the San Rafael Mountains of 

 the Coast Ranges and the Santa Ynez Mountains of the 

 Transverse Ranges. Although the deposits lie in two 

 separate geomorphic provinces (Jenkins, 1938), they 

 are geologically related and therefore are discussed 

 together. 



The deposits are situated in hilly to mountainous 

 terrain that rises from sea level to maximum eleva- 

 tions of 6,828 feet in the San Rafael Mountains and 

 4,618 feet in the Santa Ynez Mountains. The west- 

 ward-flowing Santa Ynez River divides the two 

 ranges and provides access into much of the higher 

 region. Major transportation and access routes include 

 the Southern Pacific Railroad, which follows the 

 coastline, and four state and federal highways. Ocean 

 shipping facilities are limited. Santa Barbara and Ven- 

 tura, with 1970 populations of 69,538 and 58,000, re- 

 spectively, are the largest cities in the district. The 

 nearest major marketing center is Los Angeles, 70 

 miles by road to the east of the nearest limestone 

 deposit. 



V'irtually all of the limestone and dolomite deposits 

 of the Santa Ynez district belong to formations of 

 middle Eocene (Sierra Blanca Limestone) and Mio- 

 cene (basal Monterey Formation, Temblor Forma- 

 tion?) ages. The Sierra Blanca Limestone, lying at or 

 near the base of the Juncal Formation (or the equiva- 

 lent Anita Shale), is sporadically present throughout 

 the area. This unit is the only known source of high- 

 quality limestone in the district, the Sierra Blanca 

 deposit north of Santa Barbara being by far the larg- 

 est. Here, the limestone is bioclastic, dense, hard, and 

 apparently of sufficient purity and size to be used for 

 cement, lime, and other purposes. However, its 

 remote position in the San Rafael Wilderness Area in 

 the rugged San Rafael Mountains has forestalled any 

 development of the Sierra Blanca deposit. There ap- 

 pears to be more incentive at the present to retain the 

 deposit as part of a wilderness area rather than de- 

 velop it as a mineral resource. Other deposits of Sierra 



Blanca Limestone are much smaller (thinner), less 

 pure (sandy), and principally of local interest. 



Because the Sierra Blanca Limestone has such a dis- 

 tinct fossil fauna, it has been studied thoroughly (Nel- 

 son, 1925, p. 352-354; Keenan, 1932; Dibblee, 1950, p. 

 2.5-26; Walker, 1950a; Page et al., 1951, p. 1745-1749; 

 Dibblee, 1966a, p. 20-21). Less is known about the 

 other carbonate deposits of the Santa Ynez district. 



All but one or two of the remaining deposits appear 

 to belong to the basal part of the Monterey Formation 

 (also called Monterey Shale) or equivalent middle Mi- 

 ocene formations. Two of the deposits indicated as 

 limestone by others (Aubury, 1906, p. 80; Dibblee, 

 1950, p. 34-42, 79-81, plates 1-4) have been sampled 

 and shown to be dolomite. It is suspected that other 

 occurrences of Monterey "limestone" will prove to be 

 dolomite or dolomitic limestone when tested. One 

 possible exception is the Miguelito Canyon deposit — 

 tentatively described as Monterey Formation — which 

 apparently yielded limestone for sugar refining. Aside 

 from use as a local source of crushed rock, dolomite of 

 the Monterey Formation conceivably may be of suffi- 

 cient quality in some places to be used as a refractory 

 material. However, more exploration and testing 

 needs to be done to evaluate the deposits, which com- 

 monly are sandy or siliceous. 



At least seven deposits have been utilized as sources 

 of lime and crushed rock in the Santa Ynez district. 

 About 100,000 tons of limestone from the San Migueli- 

 to deposit produced for lime, and a minor amount 

 apparently was produced at the Matilija Canyon area. 

 Perhaps as much as 2 million tons of crushed and 

 broken stone (including riprap, road base materials, 

 concrete aggregates, and filter rock) were obtained 

 from the Missile City, Bee Rock, El Jaro, Alisal, and 

 Nojoqui Canyon deposits. Production of limestone for 

 lime ceased many years ago, when reserves at San 

 Miguelito were depleted. On the other hand, produc- 

 tion of dolomite and limestone for crushed rock has 

 occurred sporadically according to need. Deposits that 

 may be of significant future interest, other than for 

 crushed rock uses, include 1) the Sierra Blanca lime- 

 stone deposit which has large reserves of good quality 

 material, and 2) various deposits which contain large 

 reserves of dolomite possibly adequate for refractory 

 or other special purposes. 



The deposits of the Santa Ynez district are de- 

 scribed alphabetically below. 



Alisal deposit. Location: Sec. 21 (proj.), T. 6 N., 

 R. 3 1 W., S.B., nearly 1 mile southwest of Solvang; Los 

 Olivos 15-minute quadrangle. Ownership: Not deter- 

 mined. 



Basal limestone of the Monterey Formation is ex- 

 posed along the south bank of the Santa Ynez River 

 where it extends west-northwest over a strike length 

 of 3,000 feet and dips steeply north. The deposit is 

 about 50 feet thick and consists of hard, light-gray, 

 algal limestone, the basal portion of which consists of 



