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



both ends. The elevation was accompanied by no fused central mass, 

 but appears to have been due to a horizontal compression, resulting 

 in a mashing together of the strata. The granite axis experienced a 

 renewed uplift, while that portion of the Coast ranges between point 

 Reyes and the Klamath mountains first emerged from beneath the 

 ocean. This theory correlates in time the youngest sedimentary strata 

 of the gold belt with the pre-Cretaceous uncrystalline series of the Coast 

 ranges. Following the upheaval, the silicification of both ranges took 

 place. A considerable interval of erosion is believed to have elapsed 

 after the former event before the deposition of the lowest Cretaceous yet 

 discovered. A subsidence continued through the Cretaceous and Eocene, 

 except for a break, not everywhere apparent, at the time of the intrusion 

 of the peridotitic eruptives. At the close of the Eocene another eleva- 

 tion took place, followed again by a depression through the Miocene, so 

 that the latter was laid down unconformably on the Chico-Tejon. At 

 the close of the Miocene another great elevation of the Coast Range region 

 was experienced. Strata of that age have at present an elevation of 

 nearly 7,000 feet in northern Ventura county. Following this other dis- 

 turbances have been recorded, but will not be touched upon here. 



Conclusions. 



The discussion in the previous pages, it is hoped, has demonstrated 

 the existence of a series of uncrystalline rocks in the Coast ranges of 

 greater age than the Cretaceous. This series underlies the Cretaceous 

 unconformably, and rests on the worn surface of the crystalline basement 

 complex. It is marked by peculiar and constant lithologic features, and 

 has undergone to a greater or less degree a silicious metamorphism, dis- 

 tinctly marking it from the younger formations. 



Attention is called to the following points, which, though less dwelt 

 upon than the main topic, are yet of great importance : 



1. The seemingly great age of the crystalline basement complex ; a 

 view which, if correct, gives the Coast ranges an antiquity greater than 

 that of a large part of the Sierra Nevada. 



2. The undoubted radiolarian origin of the jaspers of the pre-Creta- 

 ceous series, and consequently the incorrectness of applying the term 

 " metam Orphic "to them. 



3. The probable nonconformity between the Upper and Lower Cre- 

 taceous. 



4. The nonconformity between the Miocene and Chico-Tejon series. 



5. The great diversity in age and complex structure of different por- 

 tions of that continuous series of mountains known as the Coast ranges, 

 making them worthy of being considered a mountain system. 



