LITHOLOGY OF THE SEA FLOOR OFF SOUTHERN CALIFORNIA

Abstract

Rocks obtained from the sea floor off the southern California coast principally during the 1938 cruises of the E.W. Scripps have been studied in the laboratory, and the petrographic character and fossil content determined. Rock was obtained from 132 localities in such environments as the narrow continental shelf, escarpments, hills, and the walls of submarine canyons. Large size, angularity, quantity of fragments in a single haul, and the presence of fresh fractures suggest that many of the samples are representative of the bedrock outcropping at the sampling locality. The material recovered includes sedimentary, igneous, and metamorphic types. Ages were determined partly by fossil content and partly by lithological comparison with rocks outcropping on adjacent land. Triassic-Jurassic, Cretaceous, Eocene, Miocene, and Pliocene are all represented, with Miocene rocks by far the most common. The igneous rocks are predominantly andesite, although some basalt was found. The chief conclusion from this reconnaissance work is that, aside from the abundance of phosphorite, the submerged basin and range province off the southern California coast is remarkably similar lithologically to that of the bordering land areas.