BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 5, pp. 243-258 February 27, 1894 



AGE OF THE AURIFEROUS SLATES OF THE SIERRA NEVADA 



BY JAMES PERRIN SMITH 



{Presented before the Society December 29, 1893) 

 CONTEXTS 



Page 



Introduction 243 



Opinions of previous Writers 244 



Determined Horizons and well known Fossil Localities 2+6 



Review of recent Discoveries and Determinations of Fossils 246 



Carboniferous Localities 246 



Longville, Plumas County 246 



Spanish Creek and Clermont Peak, Plumas County 247 



Bear Mountain, Calaveras County 247 



Pentz Ranch, Butte County 247 



Triassic Localities 247 



Oscar Tunnel, Plumas County 247 



Rush Creek Mine, Plumas County -50 



Jurassic Localities and Fauna 250 



Texas Ranch, Calaveras County 250 



List of Fossils 251 



Mariposa Slates 254 



Russian Aucella-bearing Rocks 255 



Application of Neumayr's Theory of climatic Zones 256 



Metamorphic Rocks of the Coast Range 256 



Conclusions 257 



Introduction. 



During the autumn of 1893 the writer spent five weeks in field work on 

 the Auriferous slates of the Sierra Nevada, chiefly in Plumas, Butte and 

 Calaveras counties, California, in the effort to find some definite horizons 

 that might be identified by fossils. In this he was greatly aided by Mr 

 James E. Mills, under whose guidance he visited many of the localities 

 mentioned in this paper. To Mr Mills is due in great measure whatever 

 success was achieved by the investigations. 



XXXIV— BuLi- Geoi,. Soc. Am., Vol. 5, 1893. (2-13) 



