Santa_Susana_Formation
The Santa Susana Formation is a Paleogene period geologic formation in the Simi Hills and western Santa Susana Mountains of southern California.[1][2][3]
The formation consists largely of light-gray shale and some fine-grained shaly sandstone, with a lens of heavy conglomerates in the lower part.[1][4] Small beds of limestone are also present.[5] It is from 1,000–1,500 feet (300–460 m) thick.[1][4]