454 J. D. Dana— Kames” of the Connecticut River Valley. 
(6.) The terrace-formation of a large and broad valley was 
made mainly, not from what its river transported, but from the 
contributions of tributaries. Consequently, (a) the height of 
the maximum flood is best registered in terraces at the mouths 
of tributaries, and (6) where tributaries fail for long distances, 
there may be only low terraces ; further, (c) the coarsest gravel 
beds should exist in the deposits about the mouths of tribu- 
taries, and especially in those made along the banks of the 
main river near these mouths, where the contributions were 
subjected to the sifting action of the swiftly flowing river. 
The extent and height of the terraces made along any 
part of a valley depended not merely on the amount of con- 
tributed material, but also largely on the size and form of the 
valley. Where very wide and deep, like many lake basins, the _ 
deposits were generally sufficient to make only low or narrow 
terraces ; where narrow, the flow of waters was sometimes, be- 
cause of the diminished width, too rapid for any depositions; 
but where the valley, though narrow along the main channel had 
a broad region of ledges on either side that became overflowed 
when the waters were nearing their maximum depth, a high 
terrace might then have become of great width; for the shal- 
low region favored deposition by offering resistance to the flow, 
Il. Mr. Upham adopts in his New Hampshire Report, the 
view that the valley formations are deposits made by the flood 
from the melting glacier, and it appears from his explanations 
that he would accept without objection several of the above 
explanations. The points of discrepancy, however, are many 
and important. I cite here only those relating to the ‘“‘ ames,” 
and mostly in the author’s words, The term modified drift is 
used by him for stratified drift.* 
Page 12. ‘The oldest of the deposits of modified drift are 
long ridges, or intermixed short ridges and mounds, composed 
of very coarse water-worn gravel or of alternate layers of gravel 
and sand irregularly bedded.” “Their position is generally 
along the middle or lowest parts of the valleys.” Wherever the 
* J have avoided the term modified, because it is not known to express in all 
cases the truth, preferring the non-committal term stratijied. ; 
