ECONOMIC GEOLOGY 



195 



Triassic formation 



This formation, which is known, locally, as the red sandstone, 

 is limited in New York to a triangular area in Rockland county, 

 between Stony Point on the Hudson and the New Jersey line, 

 and to a small outcrop near the north shore of Staten Island, 

 which is the southern end of the same belt. 



The sandstones are both shaly and silicious, and the varieties 

 grade into one another. Conglomerates of variegated shades of 

 color also occur, interbedded with the shales and sandstones. 

 Formerly these conglomerates were in favor for the construction 

 of furnace hearths. They are not now quarried. The prevailing 

 color of the sandstone is dark-red to brown, whence the name 

 1 brownstone.' In texture there is a wide variation, from fine 

 conglomerates, in which the rounded grains are somewhat loosely 

 aggregated, to the fine, shaly rock and the ' liver rock ' of the 

 quarrymen. Oxide of iron and some carbonate of lime are the 

 cementing materials in these sandstones. 



The well-known Massachusetts Longmeadow sandstone and the 

 Connecticut brownstone are obtained from quarries in the Con- 

 necticut valley region, and of the same geological horizon. The 

 Littlefalls, Belleville and Newark freestones are from the same 

 formation in its southwest extension into New Jersey. 



Quarries were opened in this sandstone more than a century 

 ago, and many of the old houses of Rockland county are built of 

 it. Prof. Mather reported 31 quarries on the bank of the 

 Hudson near Nyack. The principal market was New York city, 

 and the stone was sold for flagging, house trimmings and com- 

 mon walls. The Nyack quarries have been abandoned, with one 

 or two exceptions, as the ground has become valuable for villa 

 sites and town lots. There are small quarries at Suffern, near 

 Congers Station, near New City and at the foot of the Torn 

 mountain west of Haverstraw. They are worked irregularly. and 

 for local supplies of stone. The stone is sometimes known as 

 ' Nyack stone,' also as ' Haverstraw stone.' 



