ECONOMIC GEOLOGY 203 



disappearing in Ontario county. It does not furnish any stone 

 other than for rough work and in the immediate neighborhood of 

 its outcrops. 



Calcareous tufa 

 As a supplement to the limestones the quarries in calcareous 

 tufa at Mohawk, in the Mohawk valley, and at Mumford, Monroe 

 county, should here be mentioned, although they are only of local 

 importance. 



GLACIAL DRIFT 



This material, consisting of unsorted clays, sands, gravels, 

 cobbles and boulders, is found in all parts of the state. The 

 nature of the imbedded stone varies greatly both as to variety and 

 amount. In places the deposits are full of large blocks of stone 

 and of more or less rounded and scratched boulders; in other 

 localities the hard, quartzose cobbles and small boulders predomi- 

 nate. In the sandstone districts of the southern and western 

 parts of the state the surface deposits of glacial drift contain 

 much sandstone, as in the Medina sandstone belt, the Hudson 

 river blue stone territory and the red sandstones at Haverstraw 

 and Nyack. In the Highlands and in the Adirondacks the 

 rounded, crystalline, granitoid and gneissic rocks predominate. 

 On Long Island the terminal moraine includes a great amount of 

 stone, and of many kinds. 



The cobblestones were formerly used for paving roadways, but 

 this kind of pavement is no longer laid. From the fact of the 

 stone being picked off the fields in the clearing of land for tillage, 

 the stone fragments from the drift have been known as ' field- 

 stone; ' and they were used in the earlier constructions for walls, 

 foundations and buildings, in localities where no quarries had 

 been opened. 



Some of the oldest houses on the western end of Long Island, 

 and in the Hudson river counties are built of such field stone. 

 At Yonkers the excavations for foundations and in street grading 

 afford an abundant supply of stone for common wall work. In 

 parts of Brooklyn the drift furnishes a great deal of stone in the 

 shape of huge boulders. 



