1)4') A. w. (UiAnAi; — tiik tclly li:^ikstoxe 



111 tliL' Tully region the Moscow shale, which underlies the Tuliy and 

 is strati graphically continuous with it, has a thickness of 180 feet and 

 rests directly and conformably on the Upper Ludlowville shales, but far- 

 tlier west these two formations are separated by the Tichenor limestone. 

 The Tichenor is the "Encrinal limestone" of the early New York surveys ; 

 but the name "Eiicrinal" lias also been used for a similar limestone which 

 is wide-spread in western New York and which is well shown in the ex- 

 posures on the shore of Lake Erie, north and south of Eighteen Mile 

 Creek, and in the gorge of that stream. This limestone, for which I pro- 

 pose the name Morse Creek limestone, from Morse Creek, near Athol 

 Sjirings, Erie County, New York, lies in reality below the horizon of the 

 Ludlowville shale and is the equivalent of the Centerfield limestone of the 

 (^ayuga Lake region. The Tichenor limestone is represented by the Men- 

 telli limestone, in the Genesee Valley region, but is not seen in western 

 New York, where the Ludlowville and Moscow together are reduced to a 

 thickness of IT feet at Eighteen Mile Creek. For this 17'-foot formation, 

 which has commonly, but erroneously, been called the Moscow shale, I 

 propose the name Windom. shale, from the exposures of this rock near the 

 village of Windom, in Erie County. The significance of these strati- 

 graphic variations within the State will be discussed in another paper. 



In western New York the Tully is scarcely represented, although there 

 is a \ery persistent, calcareous bed, four inches thick and only a few 

 inclies l)elow the top of the AVindom shale at Eighteen Mile Creek and on 

 the Lake Erie shore, which may indicate the Tully type of sedimentation. 

 As I have shown elsewhere, it^ and the shales which overlie it, carry a 

 fauna, in part at least, suggestive of Naples affinities, with ScJiizoholus 

 truncatus a dominant member. Spirifer tuTlius, however, also occurs 

 here, and LeiorliyncJius multico status and Anihocoelia pra'uinbona are 

 abundant. The Tully horizon is, however, represented a few miles to the 

 east, in Erie County, by a pyrite layer up to four inches in thickness and 

 generally of a lenticular character. This is seen at Spring Brook, on the 

 banks of Cazenovia Creek, and its character is essentially like that of the 

 Tully pyrite layer of the Genesee Valley, noted below. It contains an 

 abundance of pyritized fossils.^ 



The Windom is succeeded at Eighteen Mile Creek by an inch or two of 

 Genesee shale, which carries StylioUna fissurella, conodonts and the spore 

 Protosalvinia huronensis. Above this lies the Styliolina limestone, which 

 here includes about four inches of the remarkable Conodont limestone at 

 the base. 



2 Geology and Paleontology, Eighteen Mile Creek. 



•'' F. Houghton : The geology of Erie County. Bull. Buffalo Soc. Nat. Sci., vol. xi, p. 32. 



