396 H. W. TURNER — GEOLOGY OF MOUNT DIABLO. 



occur at numerous points. This is the coal-bearing formation of central 

 California. 



Miocene Beds. — These strata are largely coarse gray sandstones, contain- 

 ing Ostrea titan, Conrad, with pectens and echinoderms. The Miocene con- 

 glomerate in Pine canon contains pebbles of quartz, quartzite, and various 

 other rocks of the metamorphic series ; and one pebble of rhyolite or quartz 

 pophyry showing flow structure finely was noted. There are, however, no 

 pebbles of hornblende or pyroxene andesite. I observed a few red phthanite 

 pebbles in Miocene conglomerate by the road from the Mountain house to 

 the Railroad ranch. 



Pliocene Beds. — These beds contain fossil leaves, silicified wood, numerous 

 shells, and horublende-andesite tufa and pebbles. 



There is some discrepancy in the paleontological evidence as to the age of 

 these beds, and they are therefore treated rather fully. Some of the fossil 

 leaves obtained from them have been referred to the Miocene and others to 

 the Pliocene, by Professor Ward and Professor Lesquereux ; but there is 

 good evidence that the strata from which these different leaves came are of 

 approximately the same age. 



The shells, which are of marine origin, were considered Pliocene by Dr. 

 Gabb of the former state geological survey of California, under Professor 

 AVhituey. There are three localities at which fossils have been collected. 

 These are, Kirker pass to the north, the Railroad ranch reservoir to the south, 

 and Corral hollow, some twenty-five miles to the southeast, of the mountain. 



The Kirker pass locality has afforded the following marine shells as de- 

 termined by Gabb : 



Ih'ophoii ponderosum, Gabb ; 



Ranella californica, Hds. ; 



Purpura saxicola, Val. ; 



Lunatia lewisii, Gld. ; 



Littorina planaxis, Phil. ; 

 " remondii, Gabb ; 



Grypta grandis, Midd. ; 



Standellaf alcata, G\d.', 



Pseudocardium gabbii, Remond ; 



Gari alata, Gabb ; 



Dosinia ponderosa, Gray ; 



Tapes staminea, Con. ; 



Gyrena californica, Gabb ; 



Liropecten crassicardo, Con. ; 



Ostrcea bourgeosii, Remond ; 



Astrodapsis whitneyi, Remond.* 



* Geology of California, vol. 1, 1865, pp. .'11-32. The list as printed is not altogether that of this ref- 

 erence, but is compiled from Gabb's later synopsis of "Tertiary Invertebrate Fossils of California:" 

 Paleontology of California, vol. II, 1869, pp. 67-124. 



