1912] 



Clark: Neocene Section at Kirker Pass 



51 



scribed, is a thin layer of conglomerate. The conglomerate 

 grades up into a fine gray standstone, and a few feet above 

 the base is a thin layer of hard, dark-brown, conglomeratic sand- 

 stone, in which the following species of marine invertebrates 

 were found: Dosinia wlvitneyi, Mactra, n.sp., Nucula {Acila) 

 dalli, Marcia, cf. oregonensis, Solen rosaceus ?, Yoldia cooperi, 

 and Lunatia lewisi. Above this fossiliferous layer the sand- 

 stones grade up into a shaly and sometimes sandy tuff. These 

 beds are light gray to white in color. They are quite argillaceous 

 and crumble easily in the hand. Turner determined the tuff beds 

 of this horizon to be rhyolitic in composition, giving an analysis 

 of a specimen. The upper part of the series grades into a fine 

 sandstone which is quite fossiliferous. At several horizons im- 

 pressions of shells were found, and leaf impressions are com- 

 mon, especially toward the top. Lying unconformably on these 

 upper sandstones is the conglomerate of the basal San Pablo. 



About one mile to the east of the section described above, 

 just to the east of the Kirker Creek, the sandstones at the top 

 of the Monterey are lacking, the upper part of the Monterey 

 being a white, fairly hard, shaly tuff, which is interbedded with 

 thin layers of fine to medium coarse, sometimes cross-bedded, 

 tuffaceous sandstones. As these tuffaceous beds are followed to 

 the east, they gradually thin out. About two and one-half miles 

 to the east of Kirker Creek, on the west side of Markley Canon, 

 only ten to fifteen feet of these shaly tuffs are seen just below 

 the San Pablo. On the east side of Markley Canon the tuffs 

 are absent, and here the San Pablo rests on a lower member 

 of the Monterey. 



Fauna of Upper Monterey. — The beds described above contain 

 the following fauna : 



Cryptomya, cf. ovalis Conrad. 

 Dosinia whitneyi Gabb. 

 Modiolus multiradiatus Gabb. 

 Macoma nasuta Conrad. 

 Mactra, n.sp. 



Marcia, cf. oregonensis Conrad. 

 Nucula (Acila) dalli Arnold. 

 Panopea generosa Gould. 

 Siliqua patula var. nuttalli Dixon. 

 Solen rosaceus 1 Carpenter. 



Yoldia cooperi Gabb. 

 Amphiura, sp. ( ?) 

 Calyptraea inornata Gabb. 

 (Jancellaria, sp. (*?) 

 Cerithium, sp. (?) 

 Clavella, n.sp. 



Dentalium eonradi (?) Dall. 

 Dentalium petricola Dall. 

 Lunatia lewisii Gould. 



