G. H. Stone — Glacial Sediments of Maine. 123 



land, say from 75 to 100 miles for each of the two outer zones, 

 while northern Maine was occupied by a snow field or only 

 partially consolidated ice. During the final melting of the ice 

 these zones of sub-glacial and superficial streams would natu- 

 rally advance northward, and in course of time would cover 

 most or all of the neve area.* 



In classifying the glacial deposits a fundamental question is 

 this : What is the difference between the till and the glacial 

 sediments ? 



1. The test of stratification. One test proposed is that 

 amorphous or pell-mell drift is till while the stratified drift is 

 water drift, i. e., the sediments of glacial waters. This test is 

 a true one as a rule but not always. Thus there is a quasi 

 stratification of the clayey till of the lenticular hills, and on 

 the other hand masses of gravel, of which the stones are well 

 rounded and polished by water, have often by sliding lost their 

 stratification so that now they show no sign of intermittent 

 sedimentation. 



2. The test of composition. Unwashed moraine stuff of an 

 ice-sheet, whether sub- or infra-glacial, should contain frag- 

 ments of all sizes permissible by the nature of the rocks. 

 Practically it is not safe to affirm of any till that it is abso- 

 lutely unwashed, though a till composed chiefly of clay cannot 

 have lost any large proportion of its finest matter. No ob- 

 server can fail to notice that the terminal moraines of either 

 the great ice-sheet or those of the local White Mountain gla- 

 ciers contain much less of fine detritus than the till of central 

 and northern. Maine. Evidently there was very little moraine- 

 stuff near the extremity of the ice sheet which was not more 

 or less water-washed. The moraines of the local Androscoggin 

 glacier contain much less fine material than the till of the 



* The above stated hypotheses are consistent with the opinion of Mr. R. Chal- 

 mers of the Geological Survey of Canada that from the highlands south of the 

 St. Lawrence River in Quebec the ice flowed north and eastward. This hypo- 

 thesis would make the valley of the St. John River in Maine the area of accumu- 

 lation from whence glaciers radiated north, east and south. In a paper on 

 Glacial Erosion in Maine (published in the Proceedings of the Portland Society of 

 Natural History in 1882), I dwelt at some length on the fact that the glaciation 

 of Maine is less intense in the northern part of the State. This indicates neve- 

 like conditions prevailing over northern Maine for a large part of the glacial 

 period. This conclusion would be consistent with the hypothesis that the radiat- 

 ing flow discovered by Mr. Chalmers continued throughout the whole of the 

 glacial age, or with the hypothesis that it was only a feature of the last days of 

 the ice-sheet. For even if we suppose with Prof. Dana that the highlands near 

 Hudson's Bay were the radiating area during the time of maximum glaciation, it 

 is as yet permissible to suppose that in late glacial time the rising Champlain sea 

 melted its way up the valley of the St. Lawrence, thus isolating the portion of the 

 ice-sheet lying south of that valley. If so, the ice would for a time flow north- 

 ward from the water-shed of the St. John and from the Notre Dame hills. In 

 other words, late in the ice age northern Maine and the adjacent territory would 

 for a time be the area of accumulation from whence the ice-flow radiated, no 

 matter what may have been the earlier history of the region. 



