Abstract The southern Coast Ranges west of the San Andreas fault consist of two composite tectono-stratigraphic terranes. Paleomagnetic and geologic relations indicate that pre-early Eocene rocks in both terranes are allochthonous to the California region, and Late Cretaceous to early Eocene northward drift of 1,500 km is suspected. Basement rocks of the Salinian composite terrane are composed of middle Cretaceous granite plutons and older high-temperature metasedimentary rocks. The Salinian composite terrane is bordered on the west by the Sur-Obispo composite terrane, which includes a melange of the Franciscan assemblage (San Simeon terrane) that is structurally overlain by a Middle Jurassic ophiolite and Upper Jurassic and Cretaceous forearcbasin strata (Stanley Mountain terrane). Along the east edge of the Sur-Obispo composite terrane, an upper Campanian to lower Maestrichtian fluvio-deltaic sequence containing 102-m.y.-old to 126-m.y.-old granitic boulders lends credence to the postulated suturing of these two terranes in Late Cretaceous time. A regional unconformity that developed sometime in the span of middle(?) Paleocene to early (?) Eocene time apparently crosses both terranes. We suggest that an allochthon composed of the Sur-Obispo and Salinian composite terranes, as well as other terranes, was accreted to the southern California region in latest Paleocene or earliest Eocene time. The hypothetical Santa Lucia-Orocopia allochthon (new name) represents the amalgamated composite of these mutually exotic terranes.