THE MINING AND QUARRY INDUSTRY I915 53 



should perhaps, outside of the engineering profession. The need 

 for materials that will meet the modern requirements has made 

 necessary more care in the selection, besides preparation oftentimes 

 by sizing or washing. This development is one that promises to 

 place the industry upon a more settled basis than it has had in the 

 past. 



Sand also serves a variety of other uses, such as for glass manu- 

 facture, for making of molds for casting metals, as an abrasive, and 

 in numerous manufacturing and metallurgical operations. In most 

 of these applications the sands must meet certain definite require- 

 ments as to physical condition, mineral or chemical composition, 

 which greatly limit the available sources of supply. Their pro- 

 duction necessitates a degree of skill and technic which makes for 

 permanency in the enterprises. 



The sand and gravel beds of the State belong mainly to the 

 Pleistocene formations, accumulated as the result of the great ice 

 invasion which moved from north to south and reached as far 

 south as northern New Jersey and Pennsylvania. This ice sheet 

 swept the rocks bare of their former mantle of disintegrated 

 materials and in their place left a covering of transported bowlders, 

 gravels, sands and clays. These materials when deposited directly 

 by the ice as ground moraine are so intermixed as to have little or 

 no industrial value. Such unmodified drift covers a considerable 

 portion of the area, especially in the hilly country, whereas in the 

 valleys and lowlands it is usually concealed by beds of sorted 

 gravels, sands and clays. These latter were deposited by the waters 

 which issued from the glacier during its retreat. In some of the 

 larger valleys, as those of the Hudson, Champlain and Genesee, as 

 well as in numerous smaller ones, the glacial waters were held 

 imprisoned for a time by dams so that they stood high above the 

 present levels, and the sands and clays were deposited in a series of 

 terraces in great thickness and in well-sorted arrangement. 



Beach sands are found on the shores of Long Island and Staten 

 Island and of some of the interior lakes, notably Oneida lake. 

 These are characterized by a degree of uniformity and purity which 

 make them valuable for many purposes. The sands that have been 

 used most extensively for glass making are found on Oneida lake. 



Production. The statistics of the sand and gravel industry, as 

 collected from the individual producers, give an approximation of 

 the total business, but it is not claimed that they are complete. The 

 figures for molding sand, however, are full and reliable, since this 

 branch of the trade is on a fairly stable basis, in contrast with the 

 other branches which in general are subject to great changes from 



