THE MINING AND QUARRY INDUSTRY 955 



a large area and possess considerable economic value. They occur 

 in the Champlain valley, but mostly on the Vermont side, and on 

 the southern and western borders of the Adirondacks. From 

 the Mohawk valley at Little Falls they form a belt that extends 

 northwesterly with gradually increasing width to the St Lawrence 

 river. The area on the eastern side of Lake Champlain is continued 

 southward into Washington coimty. The limestone varies some- 

 what in character according to locality and geologic position. 

 It is often highly fossiliferous. The lower part of the group or 

 Lowville formation is a heavy bedded limestone, but the upper 

 beds commonly contain more or less shale. The color ranges 

 from light gray to almost black. It sometimes shows incipient 

 metamorphism and has a crystalline texture. The Trenton 

 limestones are quarried in Clinton, Washington, Montgomery, 

 Fulton, Herkimer, Oneida, Lewis and Jefferson counties. The 

 product is used for building and road material and common masonry. 

 A part is also burned into lime. At Glens Falls, Trenton limestone 

 is employed for the manufacture of Portland cement. 



The next group of limestones in ascending order is the Niagaran, 

 which comprises the Lockport and Guelph formations. The latter 

 is a typical dolomite, fine grained and of grayish color. It occupies 

 a limited area in Monroe and Orleans coimties, and is quarried 

 near Rochester. It has been used for lime. The lower member 

 of the group, the Lockport dolomite, outcrops in a continuous 

 belt several miles wide from Niagara Falls east to Onondaga county 

 and then with diminishing width across Madison county. Like 

 the Guelph it contains magnesia, and this component may be 

 present in sufficient quantity to make it a dolomite. The lower 

 part is usually silicious, grading into shale. The upper portion 

 which is heavy bedded is adapted for building material, road metal, 

 lime, etc. There are quarries around Niagara Falls and Lockport. 

 It is also worked at Rochester and to some extent in Wayne, 

 Onondaga and Madison counties. 



The Cayugan group with its several members is noteworthy 

 economically, as it contains the valuable gypsum and salt deposits 

 besides the hydraulic limestones that are utilized for cement. 

 The basal strata, comprising the Salina stage, are mostly shales, 

 though they are interbedded with thin layers of dolomitic lime- 

 stones. In the Cobleskill, Rondout and Manlius stages, lime- 

 stones prevail. In the Rosen dale district of Ulster coimty they 

 have furnished large quantities of material for the manufacture 

 of natural rock cement, and they are the source of the cement 



