Abstract The development of submarine canyons along active-plate margins commonly is influenced by tectonic processes. Recent studies of submarine canyons along the transform margin of western North America show that the origin and subsequent evolution of many canyons are correlatable with plate motion and plate-margin deformation. Elements of canyon morphology such as bends and meanders commonly are controlled by faults and folds that are relatable to the structural fabric of the continental shelf and slope. Some canyon heads that appear to be displaced from their lower reaches are explainable as the result of movement along strike-slip faults associated with the plate margin. Many submarine canyons along the California margin are not associated with large rivers and thus may owe their origins either to pre-Holocene fluvial or structural processes. Some modern canyons appear to be associated with pre-Pleistocene ancestral canyons. Because of both vertical and horizontal tectonic movements during the past 20 Ma, some California submarine canyons have been repeatedly filled and exhumed; the most recent exhumation began during the latest lowstand of sea level and continues today. Canyons that today have their upper reaches on the continental slope or outermost shelf, distant from large rivers or other sources of sediment supply, commonly appear to have been laterally displaced along offshore faults. Palinspastic reconstructions along these faults commonly reveal a genetic relation between such canyons and canyons heading nearshore, from which they were offset. For example, detailed studies of the Ascension-Monterey Submarine Canyon system in Monterey Bay suggest that several smaller canyons on the outer shelf and upper slope have been displaced northwestward from the headward part of Monterey Canyon by right slip along offshore faults of the Palo Colorado-San Gregorio, Ascension, and Monterey Bay fault zones. Many other canyons on the California margin have developed along, or had their courses abruptly altered by, structural zones, owing either to canyon cutting along a zone of weakness or to fault displacement. Mass wasting associated with zones of faulting and slumping, which may have been seismically induced, also may affect canyon form. Clearly, submarine canyons along the California margin commonly owe their origin and morphologic development to influences other than fluvial erosion during sea-level lowstands. A chief influence has been the San Andreas fault system.

Abstract The southern coastal and mountain area occupies about 7,000 sq mi (18,130 sq km) in the southwestern corner of California. A narrow coastal strip of sedimentary rocks extends from the Mexican border northward to the vicinity of San Onofre, where it widens and continues north around the northern extremity of the Santa Ana Mountains and southeastward beyond Corona along the Elsinore trough. The rest of the area is a mountainous land underlain mainly by the great mid-Cretaceous batholith of southern California and by older metamorphic rocks. The coastal strip and the Corona vicinity, about 1,000 sq mi (2,590 sq km), are underlain by Late Cretaceous and younger sedimentary rocks, mainly marine. About 175 wildcat wells have been drilled in the area, but evidence of oil and gas is scant. Showings of oil and gas have been reported in a few wells, but petroleum has not been produced. Three possible future petroleum target areas are Corona, the eastern part of the Capistrano basin, and the San Diego coastal strip. The volume of possibly favorable sedimentary rocks has not been quantified, but scattered bits of evidence suggest that favorable Miocene and Pliocene strata, largely in the San Diego area, may aggregate about 50 cu mi (210 cu km).