Jrom the melting of the Quaternary Glacier. 189 
The mean of the above numbers is 1,400 feet. At the last of 
the localities, the river has on its west side high rocks and 
therefore no terraces, and the bottom terrace is only 30 feet 
above low-water level. This number should, therefore, be 
thrown out, the small width having probably been compen- 
sated for by increased velocity. In this case the estimated 
mean width would be over 1,500 feet. 
For the width of the upper section of the flooded stream, or 
that above the level of the 150-foot terrace, we have the inter- 
val between the highest terraces of the two sides of the valley 
in the line of the villages of Hanover and Norwich, 8,000 feet ; 
and on a transverse line 2,500 feet below the bridge (see above), 
4,000 feet. The mean between the two is 6,000 feet. To 
obtain the area of a cross section we have. then 1,500 feet for 
the mean width of the lower section of the flooded stream, and 
for that of the upper, 210—150=60 feet. The area of the 
whole cross-section, afforded by these numbers, is 514,500 
square feet. The falls of 40 feet in the river, two miles below 
Hanover, suggest a good reason for the little height of the 
lower terraces. 
Above Brattleboro, the mean width, as nearly as we can obtain 
it from Mr. Upham’s map, is 5,000 feet. The depth, deducting 
75 feet for the lower terrace, is 135 feet; and this gives for area 
of cross section, 675,000 square feet. At the narrowest part 3 
miles north of Brattleboro, the width of the channel-way is 
3,500 feet; but this is so only for a short distance, and the 
lower terraces here have a height of but 35 to 50 feet. With 
this width and deducting only the mean between 35 and 50, or 
43 feet, for the lower terrace, the area of section is about 
585,000 square feet. . 
From these results, although not based on accurate measure- 
ments, we may conclude that the area of cross-section for the 
Connecticut, between Wells River and the Massachusetts line, 
averaged at least 560,000 square feet, and hence that the mean 
width, if 140 feet be taken as the mean depth, was probably 
not less than 4,000 feet. 
4. MEAN Stopr.—We may /irst deduce the slope or pitch on 
the assumption that the land and ocean had their present rela- 
tions as to level; and then, secondly, consider the evidence as to 
these relations having been different from now, and finally 
make other calculations in accordance with the conclusion 
reached. 
