io8 



NEW YORK STATE MUSEUM 



DUTCHESS CO. 



Fig. I Map of the Albany mold- 

 ing sand district 



of the Mohawk, which occupies 

 a broad valley that extends west- 

 ward for over loo miles, the 

 sands attain a much wider devol- 

 opment and are traceable on the 

 west bank as far as Schenectady. 

 North of the Mohawk the dis- 

 trict again narrows perceptibly, 

 but for a considerable interval it 

 is still broader than the average 

 of the southern section. 



In its limits as thus indicated 

 the district conforms with cer- 

 tain geological conditions which 

 need to be set forth before the 

 discussion of the sand deposits 

 themselves is taken up. 



The present Hudson valley is 

 an open, well-rounded excava- 

 tion in shales and sandstones 

 that belong to the so-called Hud- 

 son river formation of Ordo- 

 vician age. ' These rocks seldom 

 come to the surface within the 

 lower ground, as they are man- 

 tled by unconsolidated sediments 

 — clays, sands and gravels — 

 which evidently were deposited 

 ages ago but still rather recently 

 as geological time is reckoned. 

 The latter beds attract the notice 

 of visitors to the region owing 

 to their being arranged in ter- 

 races, which rise abruptly from 

 near the river to summits that 

 for long distances are flat and 

 preserve a uniform height. The 

 terraces attain their greatest 

 height in the north and also on 

 the west edge of the district near 

 Schenectady where their upper 

 surface is about 400 feet above 

 sea level. The general level of 



