Accession Number : AD0830816

Title :   SAN CLEMENTE ISLAND ROCKSITE PROJECT: OFFSHORE GEOLOGY. PART I. DETAILED SURVEY OFF EEL AND LOST POINTS AREA,

Descriptive Note : Technical publications.

Corporate Author : NAVAL WEAPONS CENTER CHINA LAKE CA

Personal Author(s) : Ridlon, J. B.

Report Date : JAN 1968

Pagination or Media Count : 93

Abstract : Two nearshore geophysical and geological surveys for the Rocksite Project off San Clemente Island, California, were made using continuous seismic profiling systems, geological diving, snapper sampling, and the CURV vehicle. Geologic interpretations are made relative to one of the surveys, a detailed survey off part of the west side of the island. A sequence of four sediment and rock units (A through D) is defined on the basis of the acoustical character and geometry of the acoustic reflection records. A north to northeast structural trend similar to that on the adjacent part of the island is mapped offshore. Some seaward pivotal faulting, not apparent from the island study, is suggested and appears partly responsible for the development of a submarine canyon located off Eel Point. Isopach maps of Units A, B, and C, and a structure contour map of Unit D tend to confirm this structural trend. A major unconformity is noted between Units B and C. A major insular terrace, at slightly over 100 meters in depth and prominent on the west side of the island, is postulated to have been wave-cut during Late Pleistocene to Recent time. This terrace has been affected by Recent tectonism. (Author)

Descriptors :   (*STRUCTURAL GEOLOGY, CALIFORNIA), (*LABORATORIES, UNDERWATER), MANNED, PACIFIC OCEAN ISLANDS, SEISMOLOGY, OCEAN BOTTOM SAMPLING, UNDERWATER VEHICLES, REFLECTION, OCEAN BOTTOM, MAPPING, FAULTS(GEOLOGY), UNDERWATER SOUND EQUIPMENT.

Subject Categories : Physical and Dynamic Oceanography
      Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE