DESCRIPTION OF MARBLE AND LIMESTONE QUARRIES 435 



The formation is that of the caleiferous sand rock. A large 

 area has been worked over to a slight depth. There is a thin 

 covering of earth from one to two feet thick ; then quarry beds 

 one to seven feet thick, down at least to forty feet. The dip is 

 less than five degrees to the south. 



Open and vertical, dirt-filled joints are a peculiar feature and 

 facilitate the removal of huge blocks. The long working face 

 and natural drainage are also advantages. And with a com- 

 plete equipment of steam drills, derricks and movable railways, 

 the capacit}^ of production is large. The annual output in cubic 

 yards is greater than that of any other single building-stone 

 quarry in the State, and is increasing from year to year. 



The stone is of a light blue color, and fine-grained. Its specific 

 gravity is 2.764 and its weight per cubic foot 172 pounds. A 

 partial chemical analysis gave 27.35 per cent of matter insoluble 

 in dilute hydrochloric acid. The lime and magnesia are present 

 in proportions approximating to a dolomite. The absorption 

 capacity was found to be 0.14 per cent. When treated with a 

 1 per cent, solution of sulphuric acid the loss in weight was 

 2.51 per cent. Freezing and thawing did not produce any 

 apparent effect. Exposed to a heat of 1200° to 1400° F. the 

 stone was partially calcined and crumbled with a blow. On 

 account of its hardness, it can not be dressed economically, and 

 very little of it is used for housework. It is specially adapted 

 to heavy masonry. It was used in the Arthur Kill bridge on 

 Staten Island sound, in the rear wall on. Governor's Island, in the 

 walls of the sunken track of the Harlem railroad, in the Croton 

 aqueduct gatehouse, New York city, the Poughkeepsie bridge 

 piers, and in the battle monument at Bennington, Vermont. 



Glens Falls. — There are two large quarries in the Trenton 

 limestone, one on each side of the Hudson river at Glens Falls. 

 That of the Morgan Lumber and Lime Company on the Saratoga 

 county side is no longer worked for building stone. The quarry 

 on the left bank, in Warren county, belongs to the Glens Falls 

 Company, and is worked for black limestone or " marble." 



There is a long working-face in which a gray, crystalline lime- 

 stone is seen in thin beds at the top, then the black marble, 

 which has, in two beds, a total thickness of twelve feet. 



