NEOCENE STRATIGRAPHY. 355 



valleys appearing to have been cut out of the eroded 

 pene-plane; it places the tree trunks found in so many of 

 the ravines, and the mastodon bones in the third period. 



Fig. 1. — Diagram showing movements of the Santa Cruz Mountains 

 during the Quaternary, and the development of the present topographic 

 features. I-V— Successive positions of the mountains. Dotted line — 

 Undeveloped features. Broken line — Partially developed features. Full 

 line — Developed features, a — Main ridge, b — Spring Valley, c — Summit 

 of foot-hills, d — Edge of present valley, e — Shore of San Francisco Bay. 

 NE.-SW. section through Belmont. Vertical scale five times horizontal. 



In Los Angeles County. — In the south part of the State 

 the evidence of recent submergence is in many places 

 very striking. As at Santa Cruz, wave cut terraces and 

 sea-cliffs indicate the various levels at which movement 

 has rested and given time for wave erosion. At San 

 Pedro Hill eleven of these terraces have been counted. 

 In the San Fernando Valley nine were counted, and 

 several noticed in San Gabriel Valley. These terraces have 

 been noticed by nearly all the previous writers who visited 

 the coast of Southern California. Prof. Lawson has given 

 us more accurate knowledge of these terraces at a number 

 of localities, and concludes that the movement has been 

 epeirogenic in its character.* 



At San Pedro the most recent deposit, that of the lowest 

 terrace, is quite fossiliferous in a few places. It has al- 

 ready been described in the discussion of the Pliocene of 

 San Pedro. The following shells were collected from 

 this layer : 



* Univ. of Cal., Bull. Dept. GeoL, vol. i, p. 157. 



