80 H. W. FAIRBANKS — GEOLOGY OF THE COAST RANGES. 



type has not been found to be very extensive. About San Lucia, the 

 dominating peak of the Santa Lucia range, occurs a granite with much the 

 same character, but not so coarse. In the San Jose range it is also to be 

 found. This latter granite, as shown in the slide, consists of orthoclase, 

 triclinic feldspar, quartz and mica. The large orthoclase feldspars contain 

 inclusions of the triclinic feldspars and brown mica. Grains of titanite 

 are scattered through the rock. Nearly all the sections made agree in the 

 possession of the following components : orthoclase, triclinic feldspar in 

 varying amount (in one specimen exceeding the orthoclase), quartz, 

 brown mica, occasionally magnetite, apatite and titanite. Most of the 

 specimens show glassy feldspars. Small dikes of a younger granite, quite 

 similar to that described by Dr Lawson from Carmel, are numerous in 

 portions of the San Jose and Gavilan ranges. All the specimens of granite 

 examined are remarkable for the absence of hornblende. H. W. Turner * 

 has made the following note on the granite of the Gavilan range : 



"This granite is very different from that of the Sierra Nevada. It appears to be, 

 indeed, a typical granite, and, as shown by a thin section, is composed of plagio- 

 clase, orthoclase, quartz and biotite, while the granite of the Sierra Nevada is 

 usually hornblendic, with very little orthoclase." 



The collection of granites which the writer has from the Klamath 

 mountains shows, in general, quite a different character from that of the 

 Coast ranges farther south. They resemble more the Sierra Nevada type* 

 Specimens gathered from different portions of the Trinity mountains are 

 coarse grained, with an excess of hornblende over biotite, and possess a 

 large amount of triclinic feldspar, in some specimens in excess of the 

 orthoclase. The granite of the eastern part of the Salmon range is similar. 

 Between Redding and Shasta and in the Castle Crags region the granite 

 has quite a different character and may possibly be older. 



Evidence as to Age of the Basement Complex. — Nothing definite is known 

 as to the age of the basement complex. Among the older geologists 

 opinions as to the age of the granite ranged from " Primitive " to " Mio- 

 cene." It has been shown by Dr Becker i to underlie the Cretaceous, 

 and it was considered by him that the rocks of the Gavilan range were 

 much older, possibly Primitive. Dr. Lawson J has shown conclusively 

 that Whitney's view as to its being intrusive in the Miocene is wholly 

 wrong. 



In a former paper § the writer advanced reasons for belief in the intru- 

 sion of the granite in the pre-Cretaceous series of uncrystalline rocks. A 



* American Geologist, vol. xi, p. 324. 



t Monograph on the Quicksilver Deposits of the Pacific Slope, p. 17'1. 



J Bull. Dept. Geology, University of California, vol. i, p. 18. 



§ American Geologist, vol. xi, p. 71. 



