50 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



secondary fault has evidently had its down-throw on the south 

 side, carrying down a large area of the lower Eocene which 

 was less exposed to erosion than that north of the fault, where 

 the tops of the Simi Hills have been eroded down to the Chico 

 sandstone. In this way the conglomerates of the lower Eocene 

 are offset about two miles on the surface exposure. The beds 

 dip at an angle of about 20 degrees and differ about 900 feet 

 in present elevation. In order to produce such a horizontal 

 difference, the vertical displacement must have been in the 

 neighborhood of 3000 feet. The Chico exposed in Bell's can- 

 yon and to the north-east in Dayton's canyon contains upper 

 Chico fossils and is overlain by about 8000 feet of heavy bedded 

 gray granitic sandstone. This sandstone is medium to fine- 

 grained and is interbedded in places with fine iron-stained 

 sandy shales which carry considerable carbonaceous material. 

 Conformably above these are about 200 feet of sandy shales. 

 No fossils have been found in this series but lithologically and 

 stratigraphically they resemble the uppermost Chico of north- 

 ern California. By some geologists these sandstones (fig. 1, p. 

 125) have been considered Eocene, but the writer believes them 

 to be uppermost Chico. They are unconformable with the 

 Eocene conglomerates (fig. 2. p. 125) above and also, probably, 

 with the Chico below. 



The opening of the Eocene epoch is marked by the accumula- 

 tion of about 200 feet of very coarse conglomerate of a light 

 buff color. The cementing material is coarse granitic sand. The 

 boulders, composed of polished quartzite and granite, average 

 about six inches in diameter. This conglomerate is overlain by 

 a white shaly rock about 50 feet thick. Above these are light 

 buff sandstones with Martinez fossils. North of the Simi fault 

 these fossiliferous sandstones are overlain by a series of about 

 2000 feet of drab shales with some interbedded dark gray fos- 

 siliferous sandstones in which Turritclla pachecoensis is very 

 abundant. From the upper sandstones of this series, Glyciineris 

 veatchi major, Turritella simiensis, Turritella pachecoensis, 

 Tiirritella martinezensis, Amauropsis alveata, CucnllcEa morani, 

 and Polynices hornii, have been taken. The top of these shales 

 is apparently Tejon and probably the transition from Martinez 

 takes place in this shale series, or at its base. The formations 

 are apparently conformable. 



