Topanga Formation

The Topanga Formation comprises mixed sedimentary and volcanic rocks with an erosional base (unconformity) on underlying sediments. The formation consists of basal marine conglomeratic sandstone, a more volcanic middle layer with submarine lava flows and tuffs, and an upper sedimentary breccia, conglomerate, sandstone, and a siltstone.

Common fossils

Anadara topangaensis Reinhart, 1943	Crenomytilus mathewsonii Gabb, 1866	Atrina sp.
Crassostrea titan (Conrad, 1853)	Felaniella) harfordi (Anderson, 1905)	Tellina (Peronidea) oldroydi Wiedey, 1928
Chionopsis temblorensis (Anderson, 1905)	Clementia (Egesta) pertenuis (Gabb, 1866)	Dosinia ponderosa (Gray, 1838)
Saxidomus nuttalli Conrad, 1837	.
Tegula (Chlorostoma) dalli (Arnold, 1907		Calyptraea coreyi Addicott, 1970
Trochita sp.	Bittium topangensis (Arnold, 1907)	Batillaria ocoyana (Anderson and Martin, 1914)
Turritella ocoyana Conrad, 1855	Turritella temblorensis Wiedey, 1928	Glossaulax reclusiana (Deshayes, 1839)
Ocenebra topangensis (Arnold, 1907)	Trophon (Austrotrophon) bartoni Arnold, 1910	Bruclarkia barkeriana (Cooper, 1894)
Euclia sp.	Conus owenianus Anderson, 1905
Vaquerosella coreyi Durham, 1955