50 NEW YORK STATE MUSEUM 



The characteristic fossils of the fauna of this hmestone are the 

 trilobite B r o n t e u s t ii 1 li u s and the brachiopods H y p o - 

 thyris cuboid es and Schizophoria tulliensis, 

 all of which serve to indicate definite progress in time over the 

 immediately preceding fauna. As before stated the other species of 

 the fauna are essentially those of the shales beneath and amongst 

 them Spirifer tullius, S. subumbona, Atrypa 

 spin OS a, Camarotoechia congregata, Chonetes 

 aurora and other brachiopods occur, and together with them 

 masses of cyathophylloid corals and some large orthoceratites. 



Genesee shale 



In the original section of these rocks on the Genesee river it has 

 been found important to divide the formation, restricting the term 

 Genesee to the more densely bituminous beds at the base. This is a 

 subdivision which applies wherever the formation is well developed 

 and hence throughout the region of western New York. To the 

 upper division we have given the name West River shale. In Onon- 

 daga county however and eastward to the disappearance of these 

 beds in Chenango county no such subdivision seems practicable at 

 present. Hence we include under the term Genesee shale all these 

 dark or black bituminous slaty shales appearing at this horizon 

 through a thickness of 75 feet. In the upper part there are thin 

 bands of gray shales becoming more frequent and thicker toward 

 the top and these give the beds a noticeable banded structure. The 

 horizon at which the sandy beds begin to predominate is taken as 

 the upper limit of the formation. 



The Genesee shale is seen in exposures above the cascade in the 

 Bucktail ravine and in a general way wherever the upper surface of 

 the Tully limestone is presented. It is also exposed in the upper 

 part of the ravine i mile east of Vesper; in that 3 miles west of 

 Tully ; south of Carr's quarry ; in the Ousby ravine i mile southeast 

 of Tully; above the cascade in Tinkers falls ravine and there are 

 several slighter outcrops in ravines on the north slope of South 

 mountain. 



