98 SOUTHERN CALIFORNIA GEOLOGY 



THE ABYSSAL ESCARPMENT AND 

 COAST BENCH 



The outer, or seaward, edge of the submerged con- 

 tinental margin is bordered by a very steep escarp- 

 ment of nearly 10,000 feet, which suddenly leads down 

 to the greater ocean depths. Whether this is a fault 

 line or not is a debatable question. Some may theor- 

 ize that it is the great master fault line of the Cali- 

 fornia coastal region, but no one knows. 



The coast lines of the mainland and the islands are 

 bordered by a bench with a maximum depth of one 

 hundred fathoms, which drops off suddenly to greater 

 depths. I term this the Coast Bench for convenience. 



The courses of many former land-flowing streams, 

 now submerged, may be traced across the Coast Bench 

 and the Continental Shelf. Some of these are direct 

 continuations of stream courses which still exist upon 

 the land. Others, like the one off Redondo, cannot be 

 connected with any present day stream. 



One of these stream valleys, which leads seaward 

 from Monterey Bay is a deep valley of unusual pro- 

 portions and rivals the great submerged Hudson Valley 

 of the Atlantic side in size and depth. It is traceable 

 seaward by the contours for a distance of over 80 

 miles. 



THE SUBMERGED MOUNTAIN RANGES 



The various islands off the coast of Southern Califor- 

 nia are the projecting tips to several interesting sub- 

 merged mountain ranges, which I will briefly mention 

 under the names of the Catalina and the Anacapa 

 groups. 



