210 GLACIAL GEAVELS OP MAIISE. 



stream, and perhaps a fourtli was afterwards formed in Turner north of the 

 Twentymile River. For many miles this great osar river flowed in a chan- 

 nel one-eighth to one-half of a mile wide. In this channel was deposited 

 a level plain of rather fine gravel of the type which I have named the osar- 

 plain. Whenever the system expands into plains of reticulated ridges the 

 material is very coarse. The very great size of the glacial river which 

 flowed south from Canton makes it highly probable that it drained the val- 

 leys lying north and northwest from it, including Swift River. If so, the 

 ■original gravels have been much disguised by later sediments. Indeed, we 

 might expect that during the retreat of the ice there would come a time 

 when the ice was melted over the Andi'oscoggin Valle}' but still lingered 

 toward the north, and overwash or frontal plains would at this time be 

 brought down into the main valley and cover out of sight much of the 

 ■earlier sediment. 



The length of the system from Canton to Auburn is about 25 miles. 



NOTE ON THE ANDROSCOGGIN A^ALLEY. 



For about 60 miles from Gorham, New Hampshire, to Jay, the direc- 

 tion of the Androscoggin' River is a little north of east. It is a valley of 

 preglacial erosion excavated in highly crystalline rocks, chiefly granite. 

 On each side of the river the hills rise steeply, becoming higher as the 

 White Mountains are approached. The river is bordered b}' a plain of 

 valleA' drift, '\\'hich for most of its course is less than half a mile in breadth, 

 but here and there spreads out into much broader intervals, 1 to 3 miles 

 wide. Such a plain is found in Canton. About 3 miles east of Canton the 

 river has cut through a sheet of till 70 feet thick. This body of till 

 dammed the river in the Valley Drift period and formed a lake where the 

 broad Canton intervale now is. It is probable, but not certain, that this 

 raised the level of the Androscoggin sufficiently to cause an overflow south- 

 ward to Livermore along the Bog Brook Pass. As already noted, the 

 valley di'ift of the Andi-oscoggiu is noticeable for its fineness over most of 

 the course of the river. 



HILLSIDE ESKERS IN HARTFORD. 



Whitney Pond lies a short distance southwest of Canton Village. 

 About a mile north of this pond, on the road from Canton to Sumner, are 



