11-13 



brings cool, fertile water near the coast for several months of 

 the year. The coastline has a typical beach and bluff configuration 

 with only a few shallow embayments and the unique earthquake-born 

 valley of San Francisco Bay, which, in the delta formed by the 

 confluence of the San Joaquin and Sacramento Rivers, shows what 

 erosion and sedimentation might have done along the southwest 

 coast if rainfall were greater in that area of easily erodable 

 mountains. 



Pacific Northwest Estuarine Region: Cape Mendocino to the Canadian 



border. 



The continental shelf and coastal configurations are similar to 

 those of the Pacific Southwest, but ocean water temperatures are 

 lower here; the movement of the California current away from the 

 coast is not as pronounced, and heavier rainfall has resulted in 

 some major rivers cutting through the coastal mountains to form 

 deeply embayed estuarine systems. Extensive erosion and sedi- 

 mentation have caused wide tidal flats, bars, and shoals to be 

 typical of these systems. 



The straits of Juan de Fuca and Puget Sound, which were glacier- 

 formed, do not have as severe sedimentation as exists along the 

 ocean coast, and have retained much of their original configuration, 



