Abstract
<jats:p>Submarine fan deposits of Upper Cretaceous Campanian/Maestrichtian, and Eocene ages are exposed in outcrops at San Miguel Island, the westernmost island of the Santa Barbara Channel Islands and San Diego California (Bartling and Abbott, 1984) among many other locations in California and Baja California Mexico (Howell et al., 1974; Nilsen and Abbott, 1981). The Cretaceous and Eocene deposits are in an unconformable relationship at both San Miguel Island and San Diego locations. The presence of Upper Cretaceous and Poway-clast laden Eocene inner fan submarine canyon deposits serves as a depositional pierce point to aid in reconstructing the complexly fragmented, translated and rotated Southern California Borderland, in particular placing San Miguel Island offshore San Diego in Eocene depositional time when the Poway River and submarine fan system was active, and by association, the subjacent Upper Cretaceous fan along with it.</jats:p> <jats:p>The Upper Cretaceous section at San Miguel Island is well exposed along the western portion of the island in beach cliffs and canyons and the section at San Diego viewable in beach cliffs around La Jolla and Point Loma, in canyons up the flank of Mt. Soledad and in isolated sections near Carlsbad in northern San Diego County. The deposits in both areas have similar lithology, sedimentary structures typical of inner, mid and outer submarine fan depositional settings with a diversity of clast types sourced from the Peninsular Ranges batholith and metamorphic assemblage.</jats:p> <jats:p>Large megasequences in both areas show progradation of a submarine fan depositional system out into a deep marine basin. Inner fan channel conglomerates at both locations show depositional textures including disorganized, normally graded, inverse to normally graded and imbricated clasts associated with mass sediment gravity flow, in these cases debris flows with erosional bases and coarsening upward clast sizes.</jats:p>