92 J. D. Dana—The Flood of the Connecticut River Valley 
This last remark: has no reference to the region of the 
White Mountains, where the ice may have been long continued, 
with the various phases of modern glacier-covered mountains, 
as urged by Professor C. H. Hitchcock in the first volume of 
the Report on the Geology of New Hampshire. Yet some of 
the transporting effects attributed by him to such local glaciers 
may, I think, be due to transportation by floating ice. 
2. A Channel-way a consequence of the flow in the flooded river. 
A channel-way exists as a consequence of the flow in all mod- 
ern rivers. But, according to Mr. Upham, in his Geological 
Report on New Hampshire, the filling up of the Connecticut 
valley with stratified drift took place in the era of the melting, 
or the Champlain period, and the excavation of the channel 
and the making of the terraces, in a later era. He says, p. 15: 
The material was ‘brought down by the glacial rivers from 
the melting ice sheet, or washed from the till after the ice had 
retreated ;” and by this means “ the open valleys became gradu- 
ally filled with great depths of horizontally stratified gravel, 
sand and clay.” “The modified drift thus increased in depth 
in the principal valleys through a long period, which may have 
continued until the last of the ice at the head of the valley and 
of its tributaries had disappeared.” After this came the “ Ter- 
race Period,” and during it, as the sentence following the last 
cited observes, ‘‘the rivers have been at work excavating deep 
and wide channels in this alluvium. The terraces mark heights 
at which, in this work of erosion, they have left portions of their 
successive flood plains.” “In this way the Connecticut River, 
along the greater part of its course on the west border of New 
Hampshire, has excavated its ancient high flood plain of the 
Champlain period to a depth of from 150 to 200 feet for a 
width varying from one-eizhth of a mile to one mile, leaving 
numerous terraces at each side.” 
On page 59, he says: ‘The formation of the terraces has taken 
lace by excavation of a vast deposit that filled the valley level 
with these upper plains.” On page 44: ‘‘ When the river en- 
tered upon the work of excavating its present channel in the 
alluvium, the kame was a barrier which confined erosion to 
the area on one of its sides and protected its opposite side.” 
This hypothesis makes two great floods necessary to the 
results, one for transportation and deposition, and another for 
abrasion, when, in fact, one may have done both. In an ordi- 
nary river, the powers of transportation and abrasion are com- 
i in their action; and a channel between flood-grounds 
exists because the transporting power is lessened on either side 
by loss of velocity. The channel and its alluvial borders thus 
take shape together—the former through the latter. 
