1872] | ; 83 [Perry. 
the Hudson River (for what are to-day regarded as two valleys were 
then virtually one, as well as the Valley of the Connecticut River, to 
say nothing of other north-south depressions, must have begun at last 
to receive the incoming ice-streams. These would enter somewhat 
from the glacial mass lying on the north, also from the east and from 
the west, as they slowly left the mountain heights. In this way, not 
to speak of all even by name, two greater glaciers were likely to be 
formed from these minor ice-streams, each advancing according to 
the main inclination of the surface, as favored by various attendant 
circumstances. 
But this is not all. The time doubtless came, and it may have 
» come much more speedily than has been implied, when these several 
great rivers of ice each ceased to have a separate existence. The pro- 
cesses already referred to still advancing, the ice-flow steadily making 
headway, the countless local east and west glaciers could remain no 
longer distinct. They doubtless lost themselves in, or came to be 
simply members and feeders of the various great ice streams that 
extended from the north southward, through the principal meridional 
valleys; and we may presume that they finally ceased to exhibit 
individual distinctness. The snows continuing to fall, the time must 
have arrived when all the before isolated streams of ice at last be- 
came connected. Thus they may have more and more lost their 
separate identity as the snows accumulated in the highlands, and the 
mass thickened over the plains until the whole region was covered, 
not by several isolated glaciers, as some seem to suppose, but by one 
immense sheet of ice, only interrupted here and there by a few out- 
standing mountain ridges. The agencies already mentioned continu- 
ing to operate in their legitimate way, the great winter of the ages 
having set in with all earnestness, finally every valley in the region, 
including the beds of the existing lakes, must have been filled, all the 
plains covered, and each height, save some of the topmost peaks of 
the White Mountains, shrouded in a continuous blanket of ice. Such 
being the case, there could no longer be a separate Connecticut 
_ River glacier, or a distinct one of the Hudson River, as Professor 
- Dana appears to suppose; instead of these, and of the many more 
which possibly existed at an earlier day, there was doubtless a sincle 
immense ice-sheet spreading over the country. And the formation 
and continuance of this vast expanse of ice in such force, properly 
constitute, as it is thought, the second and grand stage of the Glacial 
period. 
