The Laguna Seca Formation in the O'Neill Forebay area consists of poorly exposed white, fine-grained quartzose marine sandstone of Paleocene age. It conformably overlies the Cretaceous Great Valley sequence, dips northeastward beneath the San Joaquin Valley, and is unconformably overlain by the Plio-Pleistocene Tulare Formation.
See also
List of fossiliferous stratigraphic units in California Paleontology in California
References