The southwestern Kenai Peninsula consists of four northeast-trending pre-Tertiary tectonic units, each characterized by a different deformational style and rock assemblage. Well-bedded Upper Triassic and Lower Jurassic volcanogenic strata are laterally adjacent to a discontinuous belt of medium-grade metamorphic rocks. The Seldovia Bay complex, a deformed and locally chaotic subduction complex of probable late Mesozoic age, consisting largely of argillite, chert, graywacke, and greenstone underlies most of the area to the east of the metamorphic terrane. Farther to the southeast, the Seldovia Bay complex is adjacent to and structurally underlain by late Mesozoic turbidites of the Valdez Group. These units are integral parts of extensive parallel belts, separated by major faults, that extend from the Kodiak Islands through the Kenai Peninsula to the Chugach Mountains.