810 GEOLOGY 



By the close of the Miocene, the peneplanation of the Klui 

 and Sierra Nevada mountains seems to have approached com- 

 pletion. Much of the material eroded from these mountains had 

 been deposited in the central valley of northern California., uiviiiii; 

 the thick Miocene beds of that valley. 



In western Oregon, Miocene (Empire) beds a few hundred feet 

 thick, containing volcanic ash, rest unconformably on the deformed 



Fig. 544. Contorted beds of Monterey shale. Mouih of YaqiK-ro Cn-ck. ( 'al. 

 (Lippincott, U. S. Geol. Surv.) 



and eroded Eocene. 1 In British Columbia, there are both clastic 

 and volcanic rocks referred to this period. 



The Miocene of the western coast has not the simple structure 

 of the corresponding beds along the Atlantic and Gulf < 

 The strata have been deformed so as to stand at high angles 

 544) in many places, and locally (Mount Diablo range), they have 

 been folded, and the folds overturned so that the Chico (p. 7.VJi 

 and Tejon (p. 781) series overlie the Miocene. 2 The Miocern 



1 Diller, Coos Bay and Port Orford folios, U. S. Geol. Surv. 



2 Turner, The Geology of Mount Diablo, Bull. Geol. Soc. Am., Vol. L. 



