Champlain eras in New England. 205 
the upper surface of the glacier from the northern borders of 
New England southeastward in the line of flow would have 
been, according to the laws of fluids, very nearly uniform; and 
its average amount would have depended on the distance of the 
high, the rate of slope from the level at the White Mts, 6000 
feet, would have been 42 feet a mile (or 1 foot in 126). If it 
rence valley would have gradually fallen off into that 
New England part of the glacier. 
- he average height of the watershed is about 1,500 feet ; and 
this gives 11,500 feet for the thickness of the ice on its sum- 
mit. But the mean height of the mass is certainly 500 feet 
less, and hence the average thickness of the ice to the north 
Was not less than 12,000 feet; while over the plateau on the 
horthern borders of New England it was about 6,500 feet; in 
the region of the White Mountains, 5,000 feet; along the sea- 
shore south of Portland, 4,100 feet, the whole height there bein 
of ice; at the terminal cliffs, 500 feet above the sea level, wit 
the under surface of the glacier resting on the sea bottor is 
It should be here stated that the accumulation of ice to the 
height mentioned on the Canada watershed snaps: that there 
udson Bay. If 
there were such a movement, the region of g : 
have been to the southward of the watershed (the freest dis- 
