Santa Catalina Island is located within the California continental borderland, a geomorphic province whose origin has long been attributed to faulting within the San Andreas strike-slip system. The presence of such strike-slip faults has largely been inferred based on the topography of the ocean floor and on the presence of active seismicity on many of the apparent fault features. A strike-slip fault of significant size is present on one of the islands within the borderland (Santa Cruz), but most actual rock exposures on the other islands do not demonstrate the presence of major strike-slip faults. Study of a variety of remote sensing images and field work on Santa Catalina Island indicators of strike-slip faulting are present. Geomorphic evidence in the form of a unique drainage pattern, truncated ridges, faults and rock unit correlations all provide evidence for strike- faulting on the island.
