THE MINING AND QUARRY INDUSTRY I9I3 81 



Adirondacks and in the metamorphosed Hudson river region, how- 

 ever, they have been more or less broken up by faulting and erosion 

 and in places have a very patchy distribution. 



The Cambric limestones are found in isolated areas on the east, 

 south and west of the Adirondacks. They are usually impure, 

 representing a transition phase between the Potsdam sandstones 

 below and the high calcium limestones above. The lower beds of 

 the Beekmantown formation as originally defined are now known 

 to belong to the Cambric system. The Little Falls dolomite is 

 perhaps the most prominent member of the Cambric limestones 

 and is extensively developed in the Mohawk valley with quarries 

 at Little Falls, Amsterdam, and other places. It is a rather heavily 

 bedded stone of grayish color, suitable more especially for building 

 purposes. In Saratoga county the Hoyt limestone is in part the 

 equivalent of the Little Falls dolomite; it has been quarried for 

 building stone just west of Saratoga Springs. On the west side 

 of the Adirondacks the Theresa limestone is described by Cushing 

 as a sandy dolomite which may in part belong to the Cambric 

 system. It is comparatively thin and has no importance for quarry 

 purposes. 



The Beekmantown limestone, which is now taken as including 

 the middle and upper beds of that series as earlier defined, is 

 mostly restricted to the Champlain valley. It occurs on the New 

 York shore in rather small areas, usually down-faulted blocks, that 

 are 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 Beek- 

 mantown 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 forma- 

 tions characterized by a fairly uniform high calcium content; 

 it analyzes 95 per cent or more of calcium carbonate. It has a gray- 

 ish color and finely crystalline texture. The fossiliferous beds 

 afiPord attractive polished material which is sold as " Lepanto " 



