University of California. 



Vol. i. 



Miocene, and probably of late Pliocene age. No analyses are given. 



The comparative rarity of the type to which they belong gives 

 interest to the soda-rhyolites north of Berkeley. In this connec- 

 tion it is worthy of note that the crystalline schists found under- 

 lying this formation at Berkeley are characterized by the occur- 

 rence of minerals rich in soda, notably glaucophane, albite, and 

 paragonite. It is hoped that further study may throw more light 

 on the relations of the soda-rhyolite, both to these schists and to 

 the other volcanic rocks of this area, both of earlier and of later age. 



