Smith.) 



Islands of Southern California. 



199 



portion of the California coast, the description given by the writer* 

 for the submarine features of Santa Catalina Island would serve as 

 a general description for this entire region. (See fig. 2.) The slope 



Figure 2. — Submarine profile, southern side of Santa Catalina Island. 



of the platform is generally least between the depths of 200 and 

 400 feet. Above roo or 200 feet the slope is in general a little 

 greater, to the present coast line. Below 300 or 400 feet the slope 

 increases rapidly, being usually more or less uniform, below 600 

 feet, till the lower platform is reached. These features are not 

 equally well developed at all points, nor in quite the same way. 

 At some points the gentlest grade is between the 100- and 300-foot 

 submarine contours; occasionally the grade is more or less uniform 

 from the shore to a depth of 300 or 400 feet, and exceptionally the 

 rise from the lower platform to the shore line is not marked by any 

 pronounced terrace. 



The upper submarine platform is believed by the writer to be 

 due to marine action, — in part deposition, though largely abrasion. 

 The conclusion is based on the following reasons: (1) It borders 

 continent and islands alike, and its general characteristics are the 

 same wherever found. Since it follows the general irregularities of 

 the continental shore line and encircles all the islands, it can not 

 be due to crustal deformation. (2) It is widest in the regions 

 of greatest deposition (e. g., to the northwest and southeast of 

 San Pedro Hill) and of most active cliff-cutting; the latter cases 

 corresponding, in general, to the best development of the elevated 

 terraces. These points of greatest development of both terraces 

 and submarine platform are the salients and the gentler slopes in 

 general. It may be said that the greater breadth of the submarine 



The Geology of Santa Catalina Island, pp. 65, 66. 



