Wa7'i7ig — Lavas of Morro Hill and Yicinity. 



99 



rounded outlines as contrasted with the bowlder-strewn and 

 irregular outlines of the granitic hills of the region make it 

 locally conspicuous. The immediately surrounding area is 

 composed of ancient crystalline rocks, chiefly granitic, but there 

 are narrow zones of chloritic schist and other metamorphic 



Fig. 3. 



Map showing distribution of lavas of Morro Hill and vicinity. 



I Gray &ndes/fe 



Sca/e L. 



Moff/ec/ a/7des/7& 



P//?/( ancfes/fe. 



I 



Contour //7fery3/ /oo feet 



M/7e 



rocks. A mile to. the west, sedimentary materials of Tertiary 

 age overlie the ancient crystalline rocks, and cover the bed- 

 rock thence westward to the ocean. 



Morro Hill and the slopes immediately to the southeast are 

 of lava and tuff that seem to be of special geologic interest 

 because of their difference from other lavas of the region. The 

 materials appear to form a capping directly imposed upon the 



