BUFFALO SOCIETY OF NATURAE SCIENCES 



33 



Lithologically the beds above the Tully differ radically from 

 those below it. The deposits of lime in western New York 

 which characterized the lower members of the Devonian come to 

 an end with the Tully and thereafter the beds are characterized 

 by an ever increasing sandiness which in Erie county culminates 

 in the heavy bedded sandstones of the upper Portage. 



The Genesee beds begin above the Tully limestone, or where, 

 as in Erie county, this is absent, above the pyritiferous layer 

 representing the Tully. The lowest beds are of dense black shale. 

 These end abruptly with a thin bed of limestone which is followed 

 by sandy dark gray shales. The beds attain in Erie county a 

 thickness of not more than 20 feet. They thicken eastward until 

 at Mt. Morris on the Genesee river they are 180 feet thick. 



Genesee Shale. 



At two localities in Erie county there appears above the 

 pyrite layer a thin band of black shale. This is the dwindled 

 representative of a mass of dense, black, slaty shale which in the 



A 



E 



C 

 D 



Fig. 13. The Genesee shale. 



A. Genundewa limestone. 



B. Concretionary layer. 



C. Black shale, 19 inches. 



D. Pyrite layer (Tully horizon). 



E. Moscow shale. 



F. Houghton, Photo. 



[3] 



