MODIFIED DRIFT ALONG PINE RIVER. 149 
Review 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. 
MopiFiep DRIFT IN THE BAsIN oF PiscaTAQuA 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 occur 
* The topographic features of this basin are described in Vol. I, pp. 213-215, 302, and 313. 
