Page 2 - stitt1981

have beenirorn the LaPanza Range. PelonaSchistbearing San Francis-

quito Canyon Breccia accumulated in late Mi.ocene ('?) (Bar stovian)

tune as the Pelona Schist first became subject to erosion in northern

Soledad basin. Nonmarine alluvial fan and lacustrine deposits of the

middle to late Miocene Mint Canyon Formation unconforrnably overlie

older units east of the San Gabriel fault and apparently intertongue

with San Francisquito Canyon Breccia A late Miocene (Monnian)

marine transgression resulted in deposition of the Castaic Forma-

tion in Soledad basin while the Modelo and possibly Towsley Forma-

tions accumulated in Ventura basin. Violin Breccia intertongueS with

Castaic Formation and accumulated at the base of a Miocene San

Gabriel fault scarp Marine Pliocene Pico Formation unconforniably

overlies the Castaic Formation east of the San Gabriel fault and con-

formably overlies the Towsley Formation west of the San Gabriel

fault; it is overlain conformably by marine to nonniarine Plio-

Pleistocene Saugus Formation. Quaternary landslides, and older,

intermediate, and younger alluvium overlie older rocks throughout

the stud.y area.

The St. Francis fault may have been active in late Oligocene

and early Miocene time, removing Charlie Canyon Megabreccia by

right-slip from a possible source in the La Panza Range. The low-

angle San Francisquito fault and associated Bee Canyon fault and

San Francisquito syncline were active after deposition of the Charlie