ANDEOSCOGGIN LAKES-PORTLAND SYSTEM. 221 



of two or three broad ridges, inclosing one deep and symmetrical kettlehole, 

 besides several shallower basins. The gravel skirts the eastern border of 

 Bryants Pond and then it follows the valley of the Little Androscoggin 

 River for many miles southward. 



Sonth of Bryants Pond we have a very difficult problem, i. e., to 

 distinguish an osar-plain from valley drift on a southern slope where the 

 glacial river flowed in the same direction as the ordinary river which after- 

 wards flowed in the valley. It thus becomes necessary to state the facts 

 from which a conclusion may be draAvn. 



1. The gravel plain which extends from Rumford to North Woodstock, 

 and so on to the south end of Bryants Pond, is, without doubt, of glacial 

 origin. The ice must have covered the Androscoggin Valley or the water 

 would not have flowed southward over the divide at North Woodstock. 

 No geological fact can be more certain than that a mighty glacial river, 

 large enough to assort and polish the gravel, cobbles, bowlderets, and 

 bowlders of a plain one-eiglith to one-half of a mile wide, and that, too, on 

 an up slope of 25 feet per mile, flowed southward OA^er the North Woodstock 

 divide and thence to the south end of Bryants Pond. Such a river as this 

 can not disappear by accident, and a river capable of doing so great an 

 amount of work on an iip slope would do still more on a down slope. 



2. The osar-plain boi'ders Bryants Pond for about three-fourths of a 

 mile. If the basin where the pond now is had been bare of ice at the time 

 the gravel plain was being deposited, there would be nothing to hinder the 

 gravel from spreading out in fan shape across the whole valley. Instead, 

 the gravel is confined to a narrow belt along the east side of the pond. 

 Here was a torrent swift enough to make granite bowdders 3 feet in diame- 

 ter almost as round as marbles, and depositing- a gravel plain 10 to 20 feet 

 higher than the present jiond, strewing the margins of the pond with steej^ 

 bluffs of bowlderets and bowlders, yet scrupulously confining itself to the 

 eastern border of a moiintain valley. 



The only satisfactory explanation of these facts is that the glacial river 

 was confined between ice walls and that the area which Bryants Pond now 

 occupies was then covered with ice. True, in the pass north of North 

 Woodstock the glacial river may at this time have extended from one side 

 of the valley to the other, like an ordinary river, yet it could not have 

 followed the course it did without the presence of ice some miles to the 



