of the islands of San Miguel, Santa Rosa, Santa Cruz, and Anacapa, plus the western portion of the Santa Monica Mountains. The province is to the south of the Santa Barbara embayment, and north of the Catalinia geologic province. Mesozoic in origin, the Anacapia province consists of Late Cretaceous to Miocene age marine sedimentary up to 23,000 feet thick, including 8,000 feet of volcanic rocks, overlain by Pleistocene terrace formations. Aligned with the Santa Monica mountains, the Northern Channel Islands form a mountain system 130 miles long. This island chain appears to be a faulted east-west trending anticline. Major faults include the Santa Cruz Island Fault and the Santa Rosa Island Fault. A stratigraphic column would start with the oldest rocks, the Santa Cruz Island schist, forming an elongated core of the island, 10 miles long and 1.5 miles wide. This schist is intruded by the metamorphosed Alamos Tonalite, which has been dated 145 Ma. Just to the south of this schist is the Willows Diorite, also of the same age as the tonalite, or Late Jurassic. The only Cretaceous rocks consist of the Jalama Formation, found on San Miguel Island. Lower Tertiary sequence of rocks are found within the Christi Anticline on the southwestern part of Santa Cruz Island. The sequence includes the Pozo Formation, Canada Formation, Jolla Vieja Formation, and the Cozy Dell Formation. San Miguel and Santa Rosa islands have the Middle to Late Eocene South Point Formation, while the Cozy Dell Formation is present on Santa Rosa, along with the Sespe Formation. Middle Tertiary formations found on Santa Rosa and Santa Cruz include the Vaqueros Formation, while those two islands plus San Miguel have exposures of the Rincon Formation, and Monterey Formation. Santa Rosa and San Miguel have exposures of the basaltic and dacitic San Miguel Volcanics, which include pillow structures, while the San Onofre Breccia is found on Santa Rosa, Santa Cruz, and Anacapa. Santa Rosa Island Volcanics consist mainly of basaltic breccia, which erupted about 19 Ma. San Miguel Volcanics consist of basalt and andesite flows, which erupted between 17-18 Ma. Santa Cruz Island (SCI) Volcanics on the north side of the island consist of andesitic flows and volcaniclastics, overlying the San Onofre Breccia, and dated at about 16 Ma. The eruptive center is east of Devils Peak, and juxtaposed against the west-northwest trending strike-slip Santa Cruz Island Fault to the south. These 2400