ABSTRACT
It is sensible to divide the USA into geological provinces, each with its own character and geological history, distinguished from its neighbours by both the types and structures of its rocks.
COAST RANGES Complex series of deformed rocks along the active plate boundary of the west coast. In California the highly folded Franciscan greywackes and schists include a slice adjacent to the Sierra Nevada containing the gold mineralization of the 1849 rush. Faults include the very active San Andreas zone with its associated earthquakes and break the ranges into fault blocks further south. In the Los Angeles area, basins have up to 5 km of oil-bearing Tertiary sediments between older mountain blocks. The Peninsular Ranges have granite intruded into the metamorphic rocks. Further north, the Klamath Mountains are fault slices of Paleozoic sedimentary, metamorphic and igneous rocks, followed by Tertiary basalts along the Oregon coast, and Tertiary granites and schists forming the Olympic Mountains.
