50 



GEOLOGY OF ERIE COUNTY 



Creek, Chautauqua county. This name was found to be pre- 

 occupied and was changed to HanoYer shale because of its 

 exposure along Walnut creek in Hanover township, in which 

 Silver Creek is also situated. 



The formation is composed mainly of light gray shales with 

 occasional sandy flags. It includes three black bands. One 

 near the bottom is two feet thick. Two others in the lower half 

 of the formation are each from ten to fifteen feet thick. The 



F. Houghton, Photo. 



Fig. 24. Band of black shale included in the Hanover shales, Cazenovia 

 creek, above West Falls. 



gray shale is characterized by a heavy bedded appearance. It is 

 not fissile and does not break readily into laminae. Numerous 

 layers are composed of gray unlaminated shale filled with small 

 nodules which may range in size from an inch to two inches or 

 more in diameter, and in shape from spheroidal to irregular. 

 These nodular layers are hard and resistant and where they are 

 exposed at the level of the lake, form a projecting shelf. In 

 streams they form rapids or cascades. One such layer forms a 

 shelf at water level along the lake from Silver Creek to Havilah. 

 The three black layers are crossed by strong cleavage planes 

 which cause their surfaces to take on the appearance of a tessella- 

 ted pavement. The surfaces of these layers show plant remains. 



