MODIFIED DRIFT ALONG PINE RIVER. I49 



Revlexv and Conclusions. 



From the modified drift of Pine river, Ossipee lake, and Saco river, we 

 learn the history of this part of New Hampshire in the Champlain period. 

 After the ice-sheet had retreated from the coast, it seems for a long time 

 to have still covered the Ossipee Lake basin, and the valley of Pine River 

 and Balch ponds. The kames of this valley were deposited during this 

 time in the channel of a glacial river, which carried forward its finer 

 gravel and sand to form the plains that extend south-east from Balch 

 pond. The coarse material and irregular surface of nearly all the modi- 

 fied drift along the upper part of Pine river indicate that masses of ice 

 still remained at the time of its deposition. 



After this, the ice-sheet disappeared from the broad low basin of Ossi- 

 pee lake, and again for a long time had its terminal front at the border of 

 the low area from which it had retreated. Its moraines fill the west and 

 higher side of the narrow valley between Madison and Conway. These 

 gradually change as we come to the centre of the valley to ordinary 

 water-worn kames. This appears to have been the first outlet from the 

 melting of the ice-sheet over the Saco valley and the south-east side of 

 the White Mountains ; and the material brought down was spread out to 

 form the extensive sand and gravel plains about Ossipee lake and Six- 

 mile pond. The comparatively small amount of levelly stratified drift 

 associated .with the kames in Madison and Conway makes it probable 

 that the present outlet by Saco river was opened before the ice here had 

 wholly disappeared, so that the later alluvium was carried by this river 

 into Maine. 



Modified Drift in the Basin of Piscataclua River. 



Under this title are embraced nearly all our observations in Strafford 

 and Rockingham counties. The streams which drain this district are 

 united before reaching the ocean in Great bay and Piscataqua river.* 

 Salmon Falls and Cochecho rivers are the largest of these, and have 

 been the most thoroughly explored. Wide plains extend between these 

 rivers in Rochester. Very interesting kames and kame-like plains 



* The topographic features of this basin are described in Vol. I, pp. 213-215. 302, and 313. 



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