Smith.] 



Islands of Southern California. 



in view of the general topographic character of this side of the 

 island, that these are true raised beaches, cut in very slightly resist- 

 ant rocks, and their outlines softened by erosion. For purposes of 

 the present discussion this will be assumed to be true. 



Drifting sand is indicated on the map, at the western end of the 

 island, for a distance of about a mile and a half towards the summit; 

 also, to a less extent, at other points. These aeolian sands would 

 naturally tend still further to render any terrace features indistinct; 

 but evidently this factor, even in combination with the ready ero- 

 sion of the rocks, has not been sufficient entirely to destroy the 

 terraced character of the topography. 



The abrupt cliff on the southern side of San Miguel (forming 

 the sea-cliff for the western half of this side, and marking the rear 

 of the 40— 80-foot terrace for the eastern half) may or may not be 

 genetically a fault scarp; but its height and abruptness are due, in 

 part, at least, to wave action, undercutting previously formed ter- 

 races, and eating back into the base of the cliff. This conclusion 

 is based on the breadth of the submarine platform on this side of 

 the island, and on the presence of an elevated terrace. Whatever 

 terraces may have been previously formed on this side of the island, 

 were obliterated by the cutting which developed the 40-80-foot 

 terrace, just as this terrace, in turn, has been largely destroyed by 

 the most recent cliff cutting. 



The Rugged Islands. — Of the islands of the second group, a 

 description of the features of Santa Catalina has been given else- 

 where by the writer.* The main characteristics are the mature 

 and very rugged topography, developed in generally resistant rocks 

 (mainly quartzites and igneous rocks) ; the leveled character of the 

 summit, at an average altitude of 1,500 feet; the drowning of 

 many of the stream valleys, particularly the largest, at their mouths; 

 the terraced character of the Little Harbor region, this region 

 representing an older, structural valley (with gentle slopes), a con- 

 tinuation of which is shown by the submarine contours; the appar- 

 ent absence of terraces elsewhere. 



One of these points — the apparent absence of terraces — -needs 



*The Geology of Santa Catalina Island, Proc. Calif. Acad. Sci., 3d. Series, 

 Geol. Vol. I, No. 1, 1897. 



