BUFFALO SOCIETY OF NATURAL SCIENCES 17 



rock dissolves away and leaves the cherty constituents behind on 

 the eroded surface as a jagged, rough, sharp-edged coating. 

 This jagged appearance of weathered Onondaga limestone is 

 characteristic and not easily to be mistaken. The upper beds are 

 of purer calcareous content and freer from chert. 



The lowest layer of Onondaga limestone is a stratum of 

 limestone entirely distinct lithologically and in fossil content 

 from the beds above it. This is the layer originally called the 

 Onondaga as differentiated from the upper flinty layers which 

 had received the name of Corniferous. The lower bed differs in 

 thickness at different points in the county. A good section in 

 the Barber Asphalt Company's quarry shows it to be two feet 

 thick there. At the Carroll Bros.' quarry at the spur of the 

 West Shore Railway, near Clarence, the whole face of the quarry 

 seems to be of this bed, which must have an approximate 

 thickness of 30 feet. At the Fogelsonger quarry in Williamsville 

 it is 35 feet thick. At Akron this bed thins again to 4 feet. It 

 appears to be a great lentil, thickest at Williamsville and thinning 

 rapidly toward the east and west. 



The characteristics of this lentil are steadfast. Everywhere 

 it is a hard, gray limestone containing chert, but unlike the 

 overlying beds this chert is not disseminated throughout the 

 mass but is in concretions. The rock is a coral reef rock and is 

 one great mass of corals and crinoidal stems. The corals are 

 Cyathophylloids and Favositids. Where the surface of the bed 

 is laid bare in quarrying operations it is found to undulate and 

 on it are to be seen corals in the position in which they stood 

 when living. 



The rocks of the Onondaga formation, taken together with 

 the underlying beds of the Cobleskill and Bertie, constitute the 

 most valuable mineral asset of Erie county. They furnish 

 excellent stone for buildings, and for heavy abutments and rip- 

 rap work, or wherever a rough but obdurate stone can be used. 

 They are unfitted for finer work as their flinty constituents make 

 them extremely hard to dress. The layers most free from chert 

 have been burned for lime for nearly a century. For ballast and 

 road metal they can hardly be surpassed. Crushed stone for 

 these purposes is an important product of the quarries in the 

 formation. The lowest bed is quarried for furnace flux. 



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