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



mica-schist, in places varying to green talcose slate, often semicrystal- 

 line. These schistose rocks are crumpled in fine lines and curves as if 

 some mighty force had been exerted upon them parallel to the planes of 

 stratification. On the eastern slope of the range the talcose or hydro- 

 micaceous schists were traced north to Bully Choop, in southwestern 

 Shasta county. J. S. Diller, as well as the writer, obtained fossils from 

 an outcrop of gray limestone near the base of the range in Tehama 

 county. Mr. Diller has reported them to be Carboniferous. A limestone 

 bed quite similar is reported as far south as Toms creek. The lime- 

 stone and associated slates ought not to be confounded with the charac- 

 teristic rocks of the pre-Cretaceous series, in which limestone is very 

 rare. The rocks forming the summit of the Yallo Bally mountains to 

 the west of the Carboniferous are undoubtedly younger — perhaps middle 

 or lower Mesozoic. They are certainly not Cretaceous ; J. S. Diller has 

 given ample proof of this. 



From Lake county northward the jasper, slate and sandstone become 

 gradually more indurated, the sandstone turning to quartzite and the 

 argillaceous rocks to mica and chloritic schists, the jasper being a silicious 

 rock retaining much of its original character. The original lithologic 

 character of the series undoubtedly gradually changes toward the higher 

 portion of the Klamath mountains, and it is quite probable that the 

 horizons represented in the middle Coast ranges do not appear there. 

 As the disturbance and elevation in the Coast range axis culminated in 

 the Klamath mountains, it is but natural to expect that successively 

 younger strata would be exposed on the flanks. 



ERUPTIVES. 



General Characteristics. — The pre-Cretaceous series contains a great num- 

 ber and variety of crystalline masses intruded prior to the deposition of 

 the Cretaceous. These are exclusive of the serpentine, which is consid- 

 ered to be ot Cretaceous age. 



The glaucophane-schists are among the most striking of those rocks 

 which are supposed in part to have been derived from ancient eruptives. 

 They have been noted by the writer from Santa Barbara county north 

 to Lake county, and undoubtedly extend much farther. The glauco- 

 phane does not always form the chief constituent of these schists, but is 

 associated with actinolite, hornblende, mica, chlorite, etcetera. Some 

 geologists have considered these schists to be of sedimentary origin.* 

 It is believed, however, that thorough study will prove that many of 



* Since this was prepared for publication F. Leslie Ransome, Fellow in the University of Cali- 

 fornia, has denmonatrated that the glaucophane-schists of Angel island are the product of contact 

 metamorphism. 



