THE MINING AND QUARRY INDUSTRY I9II 79 



The lower part of the group is heavy bedded and well adapted for 

 building stone ; the upper beds commonly contain more or less shale. 

 They are used for various purposes including building and orna- 

 mental stone, crushed stone, lime, portland cement and flux. In 

 the Champlain valley quarries are found near Plattsburg, Larabees 

 Point and Crown Point; in Washington county at Glens Falls 

 where there are extensive quarries that supply material for build- 

 ing purposes, portland cement and lime. The well-known black 

 marble from Glens Falls is taken from the Trenton. Numerous 

 quarries have been opened in Herkimer, Oneida, Lewis and Jeffer- 

 son counties. The output of the last named county is specially im- 

 portant, including Hmestone for building and road construction, and 

 lime for manufacture of calcium carbide. The principal quarries 

 in Jefferson county are at Chaumont. 



The next assemblage of limestones in the order of stratigraphic 

 occurrence includes the Clinton, Lockport and Guelph members of 

 the Niagaran group. The Clinton limestone has a variable im- 

 portance in the belt of Clinton strata that extends from Otsego 

 county a little south of the Mohawk river across the central and 

 western parts of the State on the line of Oneida lake and Rochester 

 to the Niagara river. East of Rochester the limestone is relatively 

 thin, usually shaly and split up into several layers, but on the west 

 end in Niagara county it becomes the predominant member and 

 has a more uniform character. Large quarries have been opened 

 recently at Pekin, Niagara county, for the supply of flux to the 

 blast furnaces of the Lackawanna Steel Co. at Buffalo. The upper 

 beds of bluish gray fossiliferous limestone from lo to 12 feet 

 thick are the purest and analyze from 90 to 95 per cent calcium 

 carbonate. The Lockport is a magnesian limestone, in places a 

 typical dolomite, and is rather silicious in the lower part. It out- 

 crops in a continuous belt, several miles wide, from Niagara Falls 

 east to Onondaga county and then with diminishing width across 

 Madison county. The upper layers are quite heavy and yield ma- 

 terial suitable for building purposes, road metal and lime. There 

 are quarries around Niagara Falls, Lockport and Rochester. It is 

 worked to some extent in Wayne, Onondaga and Madison counties. 

 The Guelph, also a dolomite, occupies a limited area in Monroe and 

 Orleans counties and is worked near Rochester. 



The Cayugan group includes among its members the Cobleskill, 

 Rondout and Manlius limestones, which are economically important. 

 They have furnished large quantities of material for the manufac- 

 ture of natural cement, being the source of the cement rock in the 



