THE MINING AND QUARRY INDUSTRY I913 7I 



Ballston and Round lakes occurs an area which appears to be sub- 

 sidiary and parallel to the main belt that follows the river ; it repre- 

 sents an old river channel and contains a succession of glacial clays 

 and sands like that in the main valley. 



•The district is thus practically coterminous with the site of Lake 

 Albany, the name given to the expanded waters which occupied the 

 middle Hudson valley in late Pleistocene time. The series of sands 

 and clays may be traced northward from the Hudson valley into 

 the basin of Lake Champlain which also was flooded at the same 

 time, but there appears to be very little of the molding sand in that 

 section. 



The molding sand forms a layer directly below the soil. The soil 

 covering averages about a foot thick. Near the bottom it passes 

 gradually into the molding sand through a decrease of organic mat- 

 ter which is indicated by the change of color from dark gray to the 

 light yellow of the sand. In the average, the layer is from a foot 

 to 3 feet thick. Below, it gives way very quickly to a loose " open " 

 sand that lacks the clay bond and is usually a mixture of quartz 

 and shale particles. This material in turn is underlaid by the char- 

 acteristic Hudson river clays, brown or yellow on top and blue be- 

 low. The thickness of the whole sand accumulation ranges from 

 2 or 3 feet up to 10 or 20 feet and in places even more. 



The removal of the soil and molding sand is performed wholly 

 by hand labor. With the excavation of the latter, the soil is usually 

 replaced and the land is then returned to agriculture. The grading 

 of the sand according to its quality requires a degree of experience 

 and some skill of which the land owner himself is seldom possessed, 

 and the production is mainly carried on by a few firms who also 

 ship the sand to the market. The owner of the land receives a roy- 

 alty figured on the basis of yield or else a round sum for the sand 

 on the whole property. 



Most of the output comes from the central part of the district 

 from Saratoga, Albany, Schenectady and Rensselaer counties. In 

 Saratoga county, Mechanicville, Round Lake, Elnora, Burgoyne and 

 Schuylerville are the more important localities. In Schenectady 

 the sand is obtained from near the city of Schenectady and also 

 from Carman and Niskayuna. Large quantities are shipped from 

 the vicinity of Albany and from Wemple, Selkirk, Glenmont and 

 other places south of that city. In Rensselaer county the sand is 

 excavated at points along the Hudson river and the Boston and 

 Albany Railroad. The most southerly point from which shipments 

 have been made recently is Kingston. 



