148 Adventures in Scenery 



valley on an alluvial bottom about 200 feet above sea level. 

 The valley was originally occupied by a stream which flowed to 

 the ocean from the northeast. With the uplifting of the 

 mountain range, which is the high southwest side or crest of 

 the San Francisco-Marin faulted block, the stream was inter- 

 rupted or cut in two, a stream now flowing each way, one down 

 the east slope of the uplifted block to Richardson Bay and the 

 other down the west slope to the Pacific Ocean. 



Photo by G. W. Stose, U. S. Gcol. Survey 



FIG. 46. Steeply tilted rockes. San Pedro Point, west of San Francisco 

 Bay. Martinez (Eocene) formation. 



The steep slope on the east side of San Francisco Bay is the 

 fault plane which marks the southwest side of the Berkeley 

 block. Streams that flow down from the crest of the Berkeley 

 Hills, the culminating crest of the Berkeley faulted block, are 

 "consequent" streams. They flow directly to the Bay in 

 courses that were determined by the steep slope. The streams 



