284 CALIFORNIA ACADEMY OF SCIENCES. ' 



The Cretaceous is thought to be represented. The 

 strata containing lower Miocene fossils form the upper 

 part of a series several thousand feet thick. (Pescadero 

 series.) No fossils were found in the lower part of the 

 series, but it seems probable that the Inoceramus reported 

 by Prof. Whitney came from these beds, and partly upon 

 that as a basis they have been referred to the Cretaceous. 



In addition to the above are areas of granite and lime- 

 stone that are probably pre-Cretaceous. 



There are large areas of metamorphosed sandstones, 

 phthanites, serpentines and associated rocks, shales and 

 older eruptives, of which the age is as yet in question. 



Distribution of the Formations* — Granite. — While from 

 the position and character of its outcrops it seems to be 

 evident that the granite has considerable body underneath, 

 its outcrops are not very conspicuous in the Santa Cruz 

 Mountains. It occupies the ridge running from a little 

 south of Point San Pedro nearly to the San Mateo-Spanish 

 Town road; also the ridge on the west of the San Lorenzo 

 River, which extends from near Santa Cruz nearly to 

 Pescadero Creek. A little granite appears at a few places 

 along the summit of the main ridge. 



Metamorphics. — This may include the Gavilan lime- 

 stone, the metamorphic sandstone, the phthanite or radio- 

 larian chert and the older eruptives. They make up most 

 of the hills running diagonally across San Francisco from 

 Fort Point and Point Lobos to Hunter's Point and Visita- 

 cion Valley. The western side of the San Bruno Moun- 

 tains. The main ridge, starting from Mussel Rock, as 

 far as the San Mateo-Spanish Town road. The eastern 

 foothills from Milbrae to the Redwood City-Searsville 

 road. From Searsville southeast to Black Mountain and 



* The distribution is given only for the regions visited by the writer. 



