J. D. Dana—The flood from the melting Glacier. 179 
leys afford examples of this. Again, since the Champlain 
deposits that lie beneath the stony beds are made of fine material, 
there is full evidence, whether the latter were formed over the 
deposition of sand and finer gravel, with clays in some places, 
and occasional bowlders; then, finally, the upper coarse beds 
were formed wherever the waters at the flood could carry off 
the finer material or carry in coarse. 
The beds of gravel and cobble stones along Mill River extend 
for more than two miles through the New Haven plain, or 
what was then the great estuary, where there was no cause for 
rapid flow in the stream apart from a flood of enormous extent 
sweeping down the valleys. 
Depositions subsequent to the flood.—It may be questioned 
whether the flood-made upper stratum in the vicinity of the river 
courses, which has been above described, may not have been 
deposited during some flood, or era of glacier melting, later 
than that of the early Champlain period closing the era of the 
great glacier. The evidence against such a supposition in the 
localities which I have examined is decisive. For, as I have 
shown, this upper stratum when followed laterally away from 
the river courses, changes into the ordinary stratified drift ; or, 
in other words, the very same stratum bears the flood-marks 
near the river courses, and not so, or only sparingly, over other 
regions. The stratified drift of the New Haven region is evi- 
dently all one formation; it is one in structure, even to its to 
layer. All of later origin ordinarily overlying it is about a 
foot or less of blackish soil; and this is simply a portion of its 
surface sands modified by the growth of vegetation. 
ere are some portions where its upper surface was irregu- 
larly eroded, as has been explained, and there the surface was 
later built up to the old level by depositions of fine material, 
easily distinguished in kind from those below, indicative of 
changed conditions—but only a change from the flood condi- 
tion to that of the more quiet subsequent part of the Cham- 
plain period. The terrace plain near the junction of the Air 
Line and Hartford railroads has been mentioned as one local- 
the same railroad cut (that of the Air Line railroad). 
