America.

The conclusions of some of our best scholars on this subject are so
opposed to all that we would think possible, according to the present
climate and surroundings, that they seem at first incredible, and yet
they have been worked out with such care that there is no doubt of the
substantial truth of the results.

The terminal moraine of the great glacier has been carefully traced
through several States. We now know that one vast sea of ice covered the
eastern part of North America, down to about the thirty-ninth parallel
of latitude. We have every reason to think that the great glacier,
extending many miles out in the Atlantic, terminated in a great sea of
ice, rising several hundred feet perpendicularly above the surface of
the water. Long Island marks the southern extension of this glacier.
From there its temporal moraine has been traced west, across New Jersey
and Pennsylvania, diagonally across Ohio, crossing the river near
Cincinnati, and thence west across Indiana and Illinois. West of the
Mississippi it bears off to the north-west, and finally passes into
British America.<4>

All of North America, to the north and northeast of this line, must
have been covered by one vast sea of ice.<5> Doubtless, as in Greenland
to-day, there was no hill or patch of earth to be seen, simply one
great field of ice. The ice was thick enough to cover from sight Mt.
Washington, in New Hampshire, and must have been at least a mile thick
over a large portion of this area,<6> and even at its southern border it
must in places have been from two hundred to two thousand feet thick.<7>
This, as we have seen, is a picture very similar to what must have been
presented by Europe at this time.<8>

Illustration of Antarctic Ice Sheet.-----------------

The Northern Atlantic Ocean must have presented a dreary aspect. Its
shores were walls of ice, from which ever and anon great masses sailed
away as icebergs. These are startling conclusions. Yet, in the Southern
Hemisphere to-day is to be seen nearly the same state of things. It is
well-known that all the lands around the South Pole are covered by a
layer of ice of enormous thickness. Sir J. A. Ross, in attempting to
reach high southern latitudes, while yet one thousand four hundred miles
from the pole, found his further progress impeded by a perpendicular
wall of ice one hundred and eighty feet thick. He sailed along that
barrier four hundred and fifty miles, and then gave up