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



The monograph on the quicksilver deposits of the Pacific slope, pre- 

 pared under the direction of Dr Becker, was devoted mainly to the Coast 

 ranges. In it we have the results of the first detailed work done in this 

 region. 



More recently the work of J. S. Diller has extended into the Coast 

 ranges in northern California. Dr A. C. Lawson, of the State University, 

 has also made valuable additions to the geology of the central Coast 

 ranges. 



Age AND Relations of the Coast Ranges. 



VARIOUS OPINIONS AS TO AGE. 



There has not existed much diversity of opinion in regard to the age 

 of the Coast ranges until recently. This series of mountains has been 

 held by all investigators to be of geologically recent origin. Dr Trask 

 recognized the granitic formation (primitive) and the Tertiary. He 

 says : ^ ■ ■ 



* ' That the shores of the Miocene sea were primitive is proved from the fact that 

 these rocks are imposed directly on the latter, thus demonstrating that its relative 

 age with that of the northern and eastern chains is widely different and far more 

 recent." 



Jules Marcou says : f 



"What is the prmcipal age of this system of mountains? In a word, at what 

 geological epoch did it make its appearance ? I now think as I did in 1854, when 

 I saw it for the first time, that it should be referred to the end of the Eocene 

 Tertiary." 



Antisell, J in a foot-note, makes the following observation : 



"The age of an axial rock combines the idea of the first upheaval through the 

 hardened crust, and, to some extent, the period of its appearance above water, 

 though not necessarily the latter idea. The Coast ranges were upheaved and lifted 

 above the water posterior to the Miocene deposits." 



Whitney states very plainly his ideas of the age of the Coast ranges in 

 framing a definition for them ; that is, that they date from the close of 

 the Cretaceous. On page 16 of his volume on Auriferous Gravels he 



says : 



" The most striking fact in regard to the Coast ranges is that this very extensive 

 group of mountain chains is of comparatively very recent geological age. It is 

 made up of Cretaceous and Tertiary strata, with no rocks older than these showing 

 themselves in any portion of the complicated series of elevations which are prop- 

 erly included under the above designation," 



* State Senate Documents, no. 14, p. 19. 



t Wheeler's Survey, 1876, p. 172. 



J Pacific Railroad Survey, vol. vii, p. 24. 



