The area investigated is located in the northeastern corner of the Santa Clara River Basin in Los Angeles County, California, near the towns of Saugus and Newhall.
Five formations of Tertiary age, bounded on the south and east by the basement complex of the San Gabriel Range, are found in the area. The oldest formation, the Mint Canyon of upper Miocene age, is successively overlain by upper Miocene Modelo, Pliocene Pico, Pliocene-Pleistocene Saugus and Pleistocene Terrace deposits.
These sedimentary formations have been folded and faulted during two major periods of deformation, the first at the end of the Miocene period when they were acted upon by compressive forces from the north and the second period during which they were subjected to the same set of compressive forces and in addition a new set of forces which caused the uplift of the crystalline mass of the San Gabriel Range. The latter period of deformation occurred after the deposition of the Saugus formation during Pleistocene time.