146 NEW YORK STATE MUSEUM 



the district to the west ; that it was uplifted much less than the 

 Adirondacks; and that the difference in amount was made possible 

 by additional faulting, the easterly slices being thrown down rela- 

 tive to those west of them. The old fault scarps had been pene- 

 plained, along with the rest of the region. These further move- 

 ments renewed them, and their prominence today is in part due to 

 this late movement. The McGregor and Hoffman fronts of the 

 Saratoga quadrangle would "be much less imposing than they are 

 had it not been for this. 



It is by no means unlikely that further westward movement of 

 the eastern basin rocks along the thrust fault planes also took 

 place at this time. 



During the first part of the Cenozoic, the Tertiary, minor oscilla- 

 tions of level took place in the region, but we lack the precise 

 knowledge of just when and what they were. The close of the 

 Tertiary was a time of additional uplift, considerably increasing 

 the altitude of the region, not improbably with renewed faulting. 

 Succeeding this the region was invaded by the ice sheets of the 

 glacial period. 



PLEISTOCENE HISTORY^ 



Judging from the glacial history of other parts of North America, 

 the Saratoga region was probably covered by four or five successive 

 ice sheets, which extended south from Labrador and occupied the 

 territory. It was certainly occupied by two such sheets. Long 

 interglacial periods intervened between these ice sheets. The 

 glaciers interrupted the drainage, eroded the region somewhat, and 

 on retreat left it cumbered with glacial deposits. 



There were also oscillations of level during the glacial period, 

 with loss of the initial high altitude. At the time of retreat of 

 the last ice sheet the altitude of the region was lower than at 

 present. 



During the slow, northward retreat of the last ice sheet through 

 the Hudson and Champlain valleys, various bodies of standing 

 water occupied parts of the valley, south of the ice. The most 

 southerly of these, and the one of greatest importance in the 

 history of the Saratoga region, is known as Lake Albany. This 

 was a fresh-water lake which extended as far soith as Kingston 



1 Two forthcoming reports by Professors Woodworth and Stoller on the 

 Pleistocene of the Schuylerville and Saratoga quadrangles respectively will 

 fnrnish full treatment of this portion of the geological history of the region. 



