28o CALIFORNIA ACADEMY OF SCIENCES. 



Trask. — Dr. John B. Trask*, as State Geologist, made 

 a report in 1855, in which he defines the Coast Mountains, 

 also the local name of Santa Cruz Range. He divides 

 the rocks of the Coast Ranges into three groups : Ter- 

 tiary, Primitive and Volcanic. The volcanic rocks he 

 thinks to be late Miocene in age. His Primitive Group 

 included the syenites, mica schist, granite, gneiss, por- 

 phyries and the older greenstone, including also the ser- 

 pentine rocks ; he also groups with these a crystalline 

 limestone, quite common from Santa Cruz southward, and 

 makes it the same in age as the group which extends 

 through three hundred miles of the Sierra Nevada, noting 

 that it is older than the igneous rocks. In the Tertiary he 

 calls attention to the widespread existence of bituminous 

 or Monterey shale, calling it, by way of distinction, the 

 " infusorial group," and its age the " Infusorial Period," 

 but he makes them horizontal, and their exposure due to 

 simple uplift. Above this he places " sandstones and 

 slates," the former predominating. These upper beds 

 are very fossiliferous. 



Dana. — In the report of the U. S. Exploring Expedi- 

 tion, Prof. J. D. Danaf calls attention to terraces on all 

 rivers of Oregon and northern California as evidence of 

 recent lifting, and to the fiords of British America as 

 evidence of subsidence in that region. 



Blake. — In 1856 Prof. Blaket made a report in which 

 he gives a general map of the geology about San Fran- 

 cisco; he also gives sections on Yerba Buena Island, at 



* Report of the Geology of the Coast Mountaius, etc., by Dr. John B. 

 Trask. Senate, Doc. No. 14, session 1855. 



t U. S. Exploring Expedition, etc., under command of Charles Wilkes, 

 U. S. N. Vol. X, Geology, by James D. Dana, 1849, pp. 659-678. 



t Eeports of Explorations and Surveys, etc., for a railroad from the 

 Mississippi Kiver to the Pacific Ocean. 1856. Senate, Ex. Doc. No. 78. 

 Part ii, pp. 145 et seq. 



