78 NEW YORK STATE MUSEUM 



the remnants of a once continuous belt. It is also represented 

 doubtless in the basal portion of the limestone area that extends 

 across Washington and Warren counties. The only place where 

 it has been extensively quarried is at Port Henry where the purer 

 layers have been worked for flux. In the Lake Champlain region 

 it is a bluish or grayish magnesian limestone occurring in layers from 

 a few inches to several feet thick. 



The Chazy limestone is found in the same region as the Beekman- 

 town in discontinuous areas along the eastern Adirondacks from 

 Saratoga county north to the Canadian boundary. It attains its 

 maximum thickness in eastern and northeastern Clinton county, 

 and has been quarried around Plattsburg, Chazy and on Valcour 

 island. The Chazy is the earliest representative of the Paleozoic 

 formations characterized by a fairly uniform high calcium content; 

 analyses commonly show 95 per cent or more of calcium carbonate. 

 It has a grayish color and finely crystalline texture. The fossilifer- 

 ous beds afford attractive polished material which is sold as 

 " Lepanto " marble. It is used also for lime and furnace flux. 

 There are old quarries on Willsboro point, Essex county. On the 

 west side of the Adirondacks the PameHa Hmestone described in 

 the areal reports of that section belongs to the Chazy series. It 

 covers a considerable area in Jefferson county between Leraysville 

 and Clayton, and has been quite extensively quarried for building 

 stone and lime, though of subordinate importance to the Trenton 

 limestones of that section. 



In the Mohawkian or Trenton group are included the Lowville 

 (Birdseye), Black River and Trenton limestones which have a 

 wide distribution and collectively rank among the very important 

 quarry materials of the State. They are represented in the Cham- 

 plain valley, but are specially prominent on the Vermont side ; from 

 the latter area a belt extends southwest across northern Washing- 

 ton county to Glens Falls in Warren county and is continued into 

 Saratoga county. Another belt begins in the Mohawk valley near 

 Little Falls and extends northwesterly v/ith gradually increasing 

 width across Oneida, Lewis and Jefferson counties to the St Law- 

 rence river. There are isolated areas of Trenton limestones in the 

 Hudson valley south of Albany. The limestones vary in composi- 

 tion and physical character according to locality and geologic 

 position. They are often highly fossiliferous. In the northern 

 section they are mostly gray to nearly black in color, contain little 

 magnesia and run as high as 97 or 98 per cent calcium carbonate. 



II 



