GLACIAL DRIFT. 339 
ure-laden currents coming in contact with these fields of ice would have been suddenly 
condensed,—all these would have had a tendency to produce floods that are now un- 
known. 
Kames. The best examples of kames seen in Cots county are those which were 
formed as the glacier retreated from the valley of the Connecticut, in Columbia and 
Colebrook, and nowhere are they more striking than at Colebrook village. These are 
interesting, from the fact they show that for years the great glacier that filled the valley 
of the Connecticut here had its terminus. The fact that these gravel ridges do not ap- 
pear above Colebrook shows that the change of climate was such as to cause the glacier 
to disappear rapidly when it receded above that point. The expansion of the valley 
at the village and just above, and its contracted limits below, were also causes that may 
have produced this phenomenon. 
Erratics, There are very few but that have noticed, scattered through the fields, 
boulders unlike those of the rocks in the immediate vicinity. These boulders we call 
erratics or wanderers, because they have come from some distant place. Throughout 
northern New Hampshire, on account of the extensive tracts of forests, the study of all 
phenomena of drift is pursued under the most unfavorable circumstances, since in the 
forests there are no excavations, except that done by water along the streams. The 
boulders as well as the ledges are much more commonly covered with earth, or, at 
least, they are overgrown with moss, which has to be removed before we can tell 
anything about the rocks. To study thoroughly the geography of a country covered 
with forests, would, under most circumstances, be an endless task, although the area 
might be quite limited. On account of the fragile nature of many of the rocks in the 
extreme northern part of the state, boulders are not so numerous as in some other 
sections ; and the absence of granite boulders is especially noticeable. North of Con- 
necticut lake I do not remember to have seen but one granite boulder in all that 
area, and that was three or four miles east of Third lake. On Indian stream, eight or 
ten miles from its mouth, there were several boulders of conglomerate, and just north, 
three of brecciated iron ore. In Colebrook, near Mr. L. Dinsmore’s, there is a con- 
glomerate which is quite attractive even in hand specimens. None of these just men- 
tioned were found in place, and where they came from is a matter of conjecture; but 
it is altogether probable that they came from Quebec province. Most of the boulders 
found in New Hampshire as far south as Columbia are derived from the hard bands in 
the argillaceous schist, or they come from the band of hornblende rock extending from 
Colebrook to the boundary. Everywhere south-east of this band, as far as Maine and 
even beyond the Magalloway, boulders of this rock are seen. As the rock is unlike 
any other, they are noticeable wherever they may be found; and they show that the 
general direction of the drift was considerably east of south. 
In Stratford, just north of Little Bog brook, there is quite a remarkable collection of 
granitic boulders, both on account of the number and the limited area where they are 
found ; besides, they must have come from Vermont, as granitic rocks of this kind are 
not found in New Hampshire. 
