136 



University of California. 



[Vot. 1. 



tures of the island which, from a comparative point of view, are 

 most remarkable and significant: — 



1. There is no trace of an elevated wave-cut terrace, sea-cliff, 

 or strand line of any kind observable on the island. 



2. The stream topography of the island is very much more 

 advanced, i. c, much more ancient than that of either San Pedro 

 Hill or San Clemente. 



3. The island is almost cut into two parts by a low pass (less 

 than twenty feet above tide), which can only be regarded as of the 

 nature of a stream-eroded valley. The smaller of these two parts 

 has an altitude of 1,783 feet, the larger an altitude, as above stated, 

 of 2, 109 feet. 



Absence of Elevated Strands. — The entire absence of evidence of 

 the former occupation of the slopes of the island by oceanic strands, 

 indicates clearly that Santa Catalina has not been subjected to the 

 same process of emergence from the ocean which is so abundantly 

 demonstrated for both San Pedro Hill and San Clemente. It is 

 incredible that, having been subjected to the same uplift, under the 

 same conditions of exposure to wave action, similar terraces should 

 not have been formed. The only condition which might be invoked 

 to differentiate Santa Catalina from San Pedro Hill and San Clemente 

 is the petrographical character of the island, which is not uniform.. 

 The larger part of the island is, however, composed of volcanic 

 rocks not essentially different in their general field character from 

 those of San Clemente, and, although at the western end of the 

 island, the underlying pre-volcanic strata appear, their susceptibility to 

 sculpture by wave action cannot be to any practical extent less than 

 that of the rocks of San Clemente. It has been shown, moreover, 

 that the processes of shore action and of subsequent degradation 

 have left us a terraced topography on both San Pedro Hill and San 

 Clemente which is practically independent of the petrographical 

 character of those two land masses. The powerful nature of oceanic 

 shore forces belittles the effect of slight petrographical differences 

 in the material against which they are directed. It thus seems cer- 

 tain that had this island emerged from the sea pari passu with either 

 San Pedro or San Clemente, or with both, it must have been simi- 

 larly terraced. It is equally incredible that the terraces, once having 



