7/2 NEW YORK STATE MUSEUM 
ing 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 Smiths Basin; 
in Warren county at Glens Falls where there are extensive quarries 
that supply material for building 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 Jefferson counties. The output of the ‘last 
named county is specially important, including limestone for build- 
ing 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 Niagara group. The Clinton limestone has a variable impor- 
tance 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 10 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 siliceous in the lower part. It outcrops in a continu- 
ous belt, several miles wide, from Niagara Falls east to Onondaga 
county and then with diminishing width across Madison county. 
The upper layers are rather heavy and yield material suitable for 
building purposes, road metal and lime. There are quarries around 
Niagara Falls, Lockport and Rochester. It is worked to some ex- 
tent 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 inclvdes among its members the Cobleskill, 
Rondout and Manlius limestones, which are economically important. 
They have furnished large quantities of material for the manu- 
