Perry.] 93 [February 28, 
icy mass itself, but in all its concomitants. There being, on the 
whole, a slope of the country toward the south,—a vast pile 
of ice accumulating, slowly but steadily, in the northern regions; 
the wasting of the mass being, at the same time, for the most part 
on its southern border; there being thus a constant removal of ob- 
structions to progress in that direction,—the tendency to motion 
would be mainly southward. Hence ice, in unknown amount, must 
force itself slowly through the valley of Lake Champiain, and down 
that of the Connecticut River, from the great winter store-house in 
the north. These main ice-flows would be fed for a while, and 
finally impinged against, by the minor streams from the east and 
from the west. The large valleys just mentioned being at last gorged 
with ice, of course the small east and west glaciers could not any 
longer find their way into these reservoirs, for the immense pressure 
from the north must have kept them full even to overflowing. 
Hence the local glaciers might be, for a while, almost at a standstill; 
but in due time they would necessarily overflow, and begin slowly to 
move southward. ‘The vast mass of ice in the north, because of its 
ereat thickness, under the simple action of gravity, with the several 
accompanying conditions and agencies favorable to like results, must 
thus gradually extend over the region lying toward the south. So 
doing, it would tend to push southward whatever lay before it, and 
in the end it must force along, perhaps by lingering, and yet by cer- 
tain steps, not merely what some might call the upper parts of the 
mass, but all the underlying and lateral masses, which probably ex- 
isted as local glaciers in the opening of the ice period. Only one 
course, therefore, was left for what were once minor east and west 
ice-streams—they would become merged in the great glacial sheet; 
accordingly, their movement must be slowly southward, not merely 
in connection with, but as an integral part of, the vast mass of ice 
that followed the natural outlets of the region in that direction. 
Perhaps a remark should be added, in respect to the change ex- 
perienced by many local ice-streams, when they came to be part and 
parcel of the great glacial mass. This is the more needful, since the 
point seems to have been very widely misapprehended. The change 
may be illustrated by reference to the action of water, though it 
should be ever borne in mind that, while the illustration is good as it 
is used, all the conditions of ordinary streams are by no means to be 
applied to glaciers, for they do not hold. Such a change, then, as 
the one referred to, im the direction of what were probably once 
