46 



GEOLOGY OF ERIE COUNTY 



The constituents of the formation vary at its different 

 exposures, the difference being mainly in the sand content. 

 Thus the sandstone layers at Angola are thin but at Griffin's 

 Mills on'Cazenovia creek the formation includes six layers from 

 six inches to a foot thick. 



F. Houghton, Photo. 

 Fig. 20. Angola shale at Angola, showing gray shale and concretions. 



No definite line can be distinguished between the Angola 

 and the overlying Hanover shale, and there seems little reason 

 to subdivide the gray shales making up the two formations. I 

 have arbitrarily fixed the line of contact below a layer of nodular 

 grav shale about fifteen feet below a two foot black band which 



