MINERAL RESOURCES OF THE STATE OF NEW YORK 21 



morainal accumulations which rise up occasionally into hills 200 or 

 300 feet high the surface is flat ; the moraine covers only the northern 

 half of Long island. The bedded clays in places are serviceable 

 for stoneware and fire resistant materials and the sands for building 

 purposes. 



Pleistocene and recent formations. There are practically no 

 sedentary accumulations of clays or sands resulting from the 

 weathering of the subsurface rocks an3avhere in the State. Instead 

 the whole area is mantled by a heterogeneous assemblage of bowlders, 

 gravels, sands and clays, foreign to the localities in which they 

 occur. It is not uncommon to find great bowlders of some of the 

 Adirondack rocks or material from the Canadian highlands at remote 

 distances from their origin. These erratics, as well as the finer 

 materials that are spread over the surface without reference to the 

 underlying formations, were deposited by the Pleistocene ice-sheet 

 which had its sources in the Labrador region of Canada. A collec- 

 tive name for the materials is drift. There is considerable variation 

 in the method of occurrence of the drift. The most general form 

 of deposit is the ground moraine which usually lies directly upon 

 the rocks and consists of a mixture of sand, pebbles and stiff blue 

 clay. It represents mainly the materials melted out of the ice 

 during the retreat of the glacier to the north. It is spread more 

 or less evenly, seldom having a thickness of more than 15 to 20 

 feet. In places, however, it rises up into ridges 100 feet or more 

 high of characteristic outline, having an elongated oval base and 

 smooth contours that rise more sharply on the north side than on 

 the south. Their longer axis is parallel with the direction of the 

 ice movement which varied from southwest to southeast and locally 

 trended nearly east or west. Drumlins abound in central and 

 western New York. The drift is sometimes in rudely sorted condition 

 as hillocks or kames and long winding ridges or eskers, the result 

 of deposition by the running waters at the end of and under 

 the ice. The obstruction of the earlier drainage by the drift brought 

 into existence many lakes and not infrequently shifted the larger 

 streams into new channels. The surface waters have modified the 

 forms left by the ice to some extent, but broadly the topography 

 is that of a recently glaciated country. 



The surface deposits yield quite an assortment of products. The 

 clays are of predominant importance industrially, owing to the 

 extensive local markets for clay -building materials. They are low 

 grade and suitable only for brick and common wares, but have a 

 wide occurrence. The best clays are the water-sorted beds, like 



