PLEISTOCENE GEOLOGY OF MOOERS QUADRANGLE 7 



which can be explained only by the former presence of an ice 

 front along the flanks of the uplands. 



All the facts indicate that the ice moved into northeastern New 

 York in a southwesterly direction. Passing over the St Lawrence 

 plain the ice moved southeastward into northwestern Vermont, 

 and southward into the valley of Lake Champlain, pressing 

 more strongly against the Adirondacks than against the eastern 

 side of the valley. Another part moved southwestward up the 

 St Lawrence valley into the basin of Lake Ontario. As the 

 ice-sheet culminated in thickness and southward extension, it 

 advanced over the outlying spurs of the Adirondacks, such as 

 for instance Dannemora mountain, shown on the Mooers quad- 

 rangle. It moved up over the low platform of Potsdam 

 sandstones flanking the Adirondacks on the north, with a 

 southwesterly direction. The eastern margin of this platform 

 forms the belt of higher ground entering the Mooers quadrangle 

 from the northwest and extending through the Flat Rock area of 

 Altona. Over most of this belt the ice moved under the influence 

 of the relief of pressure which was found to the southwestward 

 along the western base of the Adirondacks. On the south and 

 east of this area the ice was drawn into the Champlain flowage. 

 Thus we have in this district the topographic versant on which 

 the ice divided, one tongue going southward to form the Oham- 

 plain-Hudson glacier and the other southwestward to form the 

 greater St Lawrence glacier. So far as present knowledge goes, 

 it would appear that at the maximum of glaciation the ice passed 

 quite over the Adirondacks, though it must have been in the high- 

 est part of that region much slackened in flow as compared with 

 the freer run of the ice through the large valleys on either side. 



In the till-covered area of the map, accompanying this report, in 

 which district nearly all the striae were observed, the color repre- 

 senting the till might be made to express by a linear design the 

 approximate direction of striation, and thus the lines along which 

 the till of any particular place presumably has been transported. 

 In such a pattern, of course, where observed striae are relatively 

 infrequent, the lines of flowage must be largely interpreted; and 

 in the southern part of the area, particularly in Dannemora, it 

 may be that the striae when found would deviate somewhat from 



