EVIDENCE OF VALLEY GLACIERS 443 



also made of similar boulder accumulations is proved by the fact that, 

 even when the stream draining the South basin reaches as far as the 

 " dry pond," the water generally sinks through the sand and entirely 

 disappears. The only time when there is water in this " dry pond " is 

 during the spring freshets. There is evidently an accumulation of loose 

 boulders here into which the water sinks as it might into the pores of a 

 sponge. Even above this pond the same condition is proved to exist 

 by the fact that after every heavy rain the brook advances toward the 

 " dry pond " and then quickly disappears. Our camp was located at 

 the junction of the brook with the " dry pond," with a plentiful supply 

 of water on the first night ; but each day it was necessary to go farther 

 and farther up the stream for our water supply. 



One possible explanation of ridges of drift with a large percentage of 

 local material is that of crag and tail ; but the form and position of these 

 ridges disprove that explanation. It might be suggested that these boulder 

 accumulations (see plate 37) are ancient avalanches; but this is impos- 

 sible, for they are too far away from the cliffs ; and, moreover, there are 

 similar moraines a mile farther from the mountain than these. As has 

 been stated, the boulders of both moraines are mainly of Ktaadn granite, 

 which of itself is evidence of local rather than general glaciation. Very 

 few foreign fragments, and those of small size, were found in a careful 

 search among the boulders. Moreover, many of the fragments, especially 

 in the basins, are remarkably fresh, as if recently brought to their present 

 position. 



Beyond the entrance to these basins hummocky deposits still continue, 

 and although the region is forest-covered and exceedingly difficult to 

 examine, it requires but a few sections across the country to find evi- 

 dence of the morainic nature of the deposits ; but even without this, there 

 is a chain of ponds, extending at right angles to the axes of the basins 

 and at a distance of a mile or two from their mouths, which are evidently 

 located behind a dam of terminal moraine (see plate 38) formed by the 

 union of two glaciers, one from the North basin, the other from the South 

 basin. This chain of ponds consists of three rather large ones (see 

 plate 39), which Hamlin has located on his map (see plate 31), and two 

 others which he has not placed there. 



The morainic wall which incloses the ponds is almost impossible to 

 examine in detail, for it is covered with a low, tangled brush of spruce 

 and birch (the "pucker brush " of the Maine woods), through which it 

 is impossible to push one's way, under which one can not go, leaving but 

 one remaining means of travel — to pass over it. It was brush of this 

 kind, and in this region, on which Thoreau says that he walked for some 

 distance, actually traveling on the tops of the stunted trees. 



