REPORT OF THE DIRECTOR I915 169 



disappearance of the ice, and some of it in the beds of the glacial 

 lakes forming small lacustrine deposits. 



In the Champlain valley all these phenomena, till sheet, terraces, 

 marginal moraines and lake beds, b^ve been modified subsequently 

 by the wave action of the body c'„ water that occupied the basin 

 between the Adirondacks and the Green mountains. This extinct 

 body of water is known as Glacial Lake Champlain or the Lake 

 Vermont of Woodworth. At this time the end of the glacier must 

 have extended right across the valley, a splendid ice cliff from 

 which huge bergs were continually breaking off into the great body 

 of water that it held in as a dam from mountain wall to mountain 

 wall. Over this expanse floated the bergs, sometimes dropping 

 scattered boulders from their mass into the bed of the lake. 



S GENERAL FEATURES OE THE LOCAL GLACIATION 

 The main valley glacier pushed a subsidiary lobe into the Crown 

 Point embayment. Without sufficient momentum to force itself up 

 over the western hills, its progress was blocked by their massive 

 bulk, and retarded here by friction against the mountain barriers, 

 its load of rock was dumped from the edges in gigantic moraines 

 that now lie heaped against the mountain sides. The retreatal 

 moraines that the ice tongue left behind it as it withdrew from the 

 embayment have been greatly modified by the subsequent action of 

 waves, 'by lacustrine deposits, and by more recent stream erosion. 

 Into the sides of these moraines the waves of each glacial lake cut 

 shore lines at the level of its altitude. Between these water levels 

 the original topography, untouched by movement of the surface 

 water, remained unaltered by wave action. But it was modified 

 somewhat by bottom deposits of silt brought in by two drainage 

 streams from the mountainous region to the west. Although recent 

 erosion has dissected these bottom deposits, they are still distinctly 

 recognizable as such. 



At the highest stage of the glacial lake Sugar hill, was entirely 

 submerged, and the waters extended to the higher hill behind It 

 (see map i). Subsequently, at a lower level of the glacial lake. Its 

 summit formed an Island connected with the mainland by a sandpit 

 In Its lee (maps 2 and 5). At this stage of the lake Sugar hlllwas 

 not entirely submerged. Only the highest portions rose, above the 

 surface of the waters, including that portion south of the fork of 

 the road that runs southward from Crown Point village, and also, 

 probably, some bare ledges of rock on the extreme eastern end. 



