Smith. 1 



Islands of Southern California. 



181 



stack to San Nicolas. These four islands are widely separated, but 

 each one of them, as well as the group of northern islands as a whole, 

 has a general trend parallel to that portion of the coast to which 

 each is nearest. A submergence of the coast of 100 feet would add 

 to the southern group of islands San Pedro Hill, situated on the 

 main coast to the north of Santa Catalina; while a minimum eleva- 

 tion of about 175 feet would add to the group as islands what are 

 now three submarine elevations known as Cortes, Tanner, and 

 Osborn Banks. Cortes Bank is situated about forty miles southwest 

 of San Clemente, Tanner Bank lying about ten miles to the north of 

 Cortes Bank (see fig. 1). Osborn Bank lies about five miles south 

 of Santa Barbara Island, and has a northwesterly and southeasterly 

 trend, which, like that of the islands in general, is roughly parallel 

 to the neighboring mainland coast. 



Besides the islands already named, there is a small group, Los 

 Coronados Islands, about ten miles off the coast of San Diego 

 county. An elevation of the coast amounting to 175 feet would 

 join this entire group to the mainland. On account of their size 

 and situation, these islands will not be further considered. 



Only San Pedro Hill, Santa Catalina* and San Clemente 

 Islands have been visited by the writer. The information concern- 

 ing the other islands is therefore indirect, gleaned in small part 

 from the meager notes which have been published concerning them 

 by the Geological Survey of California, the California Academy of 

 Sciences, and in the various annual reports of the State Mineral- 

 ogist. Nearly all of what follows, however, is based on a study of 

 their topography as shown on the charts of the United States Coast 

 and Geodetic Survey. 



The islands may be divided topographically into two groups, 

 independently of their geographical arrangement. The one group 

 has simple topography, with comparatively gentle slopes and 

 moderate or slight dissection; the other has rugged, sharply 



*The study of Santa Catalina (see Proc. Calif. Acad. Sci., Third Series, 

 Geol., Vol. I, No. 1, 1897) was made independently, without any attempt to 

 correlate its features with those of the neighboring land areas. Further inves- 

 tigation has led to some modifications of the views therein put forth, as indi- 

 cated by the statements made in this paper. 



