I 



GLACIAL GEOLOGY OF THE SCHENECTADY QUADRANGLE Ij 



Albany. Southward from Schenectady lies the sand plain region, 

 the materials of which are described by Woodworth^ as " the most 

 extensive deposits of this nature (delta) in the Hudson if not also 

 in the Champlain valleys." A portion of this plain, developed in its 

 characteristic topographic features — a generally flat surface marked 

 by many low hills and ridges of sand — occupies the southwestern 

 portion of the Schenectady sheet. Eastward of this lie the hills of 

 till in the town of Niskayuna which, however, are largely covered 

 by blown sand. Farther to the east and south of the Mohawk an 

 area of sandy clay broken by hills of till and dissected by streams 

 extends to the eastern boundary of the sheet. On the eastern side 

 of the sheet a broad and unbroken area of sands extends from the 

 Mohawk channel northward to the Round lake depression. North 

 of the depression the sands again appear forming a plain lying be- 

 tween the Round lake basin and that in which Saratoga lake lies. 

 The margins of this plain are deeply gullied by the small streams 

 tributary to the lakes. 



These areas of sands and clays are continuous, except as broken 

 by the Mohawk channel and the obvious water course across the 

 Round lake region. The inference that they are deposits made in 

 one body of water is scarcely open to question. They constitute, 

 however, deltas built into Lake Albany from different sources and 

 under varying conditions. The deposits near Schenectady were 

 brought down by the IMohawk during the flooded or Iroquois stage 

 of that river. The Mohawk delta thus formed became confluent to 

 the south and east with deposits made from waters moving in the 

 general valley of the Hudson. The deposits in the eastern part of 

 the Schenectady sheet both north and south of the Mohawk, belong 

 largely, if not wholly, to the Hudson valley accumulations. A reser- 

 vation is made in recognition of the possibility that, after the gorge 

 below the Aqueduct began forming, the Mohawk deposited sedi- 

 ments in the basin below Vischer Ferry. 



In addition to the areas above described there are others of less 

 extent composed of similar materials and believed to be deposits 

 made in Lake Albany. Two of these are crossed by the northern 

 border of the sheet. Their surfaces are on the same general level 

 as that of the Malta plain to the east and they are evidently por- 

 tions of the same mass cut off by water courses. A more isolated 

 area occurs west of the southern part of the Ballston channel in the 

 town of Glenville. This presents the same features as to materials, 



^Ancient Water Levels. N. Y. State Mus. Bui. 84, 1905. p. 130. 



