BUFFALO SOCIETY OF NATURAE SCIENCES 15 



In Ohio this breccia is represented by a conglomerate 

 of ' ' large and small water-worn pebbles of the underlying 

 formation embedded in a matrix of Columbus limestone." This 

 has been included in the Columbus (Onondaga) limestone. 



Onondaga Limestone. 



Lying above the Cobleskill limestone and forming the cap of 

 the escarpment which extends from the Niagara river to Akron 

 is a heavy formation of limestone to which has been given the 

 name of Onondaga limestone. 



. The name Onondaga limestone was used by Professor Hall 

 to designate a layer of limestone lying between the Oriskany 

 sandstone and a great mass of flinty limestone which lay in 

 contact with the Marcellus shale above it. The flinty mass he 

 named the Corniferous limestone. At the same time he expressed 

 his opinion that the two limestone masses, the Onondaga and 

 Corniferous, " for all practical purposes, may be regarded as one 

 formation." Professor Eaton described them together as the 

 Corniferous limerock. Dr. Clarke has abandoned the use of the 

 name Corniferous and has applied the name Onondaga to all the 

 deposits between the Marcellus shale and the Oriskany sandstone 

 or its horizon, embracing the former Onondaga, Corniferous and 

 Seneca. In Ohio this is called Columbus limestone. 



The Onondaga limestone is the last great deposit of limestone 

 in New York. It was preceded by the great deposits of Trenton, 

 Clinton, Niagara and Salina times but was followed by minor 

 beds only, intercalated between the tremendous deposits of shale 

 of later Devonic time. It attains a thickness of 162 feet measured 

 in a well of the Lackawanna Steel Company, but it thins eastward 

 and in Onondaga county it is but 65 feet thick. It extends 

 westward into Ontario. At all points it is constant in its 

 lithological structure and its fossil content. 



The Onondaga limestone is a mass of hard, compact 

 bluish-gray limestone bedded in layers from a foot to two feet 

 in thickness, usually separated by thin seams of carbonaceous 

 material- Incorporated in the limestone are irregular nodules 

 and layers of chert which in some of the layers make up a large 

 proportion of the rock mass. The chert is black to bluish-gray 

 in color, sometimes translucent in thin sections. It is extremely 

 resistant to erosive agencies. In weathering, the lime in the 



