Smith.] 



Islands of Southern California. 



and is still in its infancy. It consists, on the southern side — where 

 well developed — of long, trough-like forms, having a general direc- 

 tion at right angles to the trend of the island, and separated by 

 broad stretches of undissected, terraced surface. Some of the 

 channels on this side of the island scarcely more than notch the 

 terraces over which they flow ; few have cut down to sea level. A 

 small lagoon is formed near the mouth of at least one stream, 

 near the southeastern end of the island, which has cut its channel, 

 in its lower reaches, in soft Miocene shale, and in a region of 

 considerable shore drift. The drainage of the northern slope 

 consists of numerous short, steep-graded streams, which have 

 scored this side of the island, in the steeper and higher parts, with 

 comparatively shallow valleys. 



The description of the general topographic features of San 

 Clemente would apply, with little modification, to San Nicolas, 

 which lies to the northwest of it. San Nicolas differs mainly in 

 size, and in having its fault scarp facing the ocean instead of facing 

 the land. The island is nearly nine miles in length, with a 

 maximum width of three and three-quarters miles. Its highest 

 point is 890 feet in altitude, and lies in the ridge which extends 

 the whole length of the island, nearer the southern side, at an 

 average distance of a mile from the shore. The rocks of the 

 island are sandstone (according to Dr. Cooper J and Dr. Stephen 

 Bowersf), and are therefore readily weathered. Bovvers gives the 

 dip as northerly, about 13 to 15 . 



The gentle slope of the island is toward the north, and this 

 side is distinctly terraced. So far as known to the writer, however, 

 no definite terraces occur on the southern and more exposed side, 

 where, if the development of terraces depended on the power of the 

 waves alone, we should most expect to find them. Cooper! has 

 mentioned three "raised beaches" on the island, at elevations of 

 30, 80, and 300 feet. The flat-topped summit, also, is without 



*Geol. Surv. of Calif., Geol., Vol. I, 1865, p. 184. 



t Calif. State Mining Bureau, 9th Ann. Rept., State Mineralogist, for 1889., 

 P- 57- 



% Loc. cit. 



