It also shoves
out a moraine along each side of its course.
Imposing as the modern glaciers are, they are not so
huge as were some that once existed. For instance,
Mr. Whymper says:
"At some very remote period the Valley of Aosta was occupied
by a vast glacier, which flowed down its entire length from
Mont Blanc to the plain of Piedmont, remained stationary,
or nearly so, at its mouth for many centuries, and deposited
there enormous masses of debris. The length of this
glacier exceeded EIGHTY MILES, and it drained a basin
twenty-five to thirty-five miles across, bounded by the
highest mountains in the Alps. The great peaks rose
several thousand feet above the glaciers, and then, as now,
shattered by sun and frost, poured down their showers of
rocks and stones, in witness of which there are the immense
piles of angular fragments that constitute the moraines of Ivrea.
"The moraines around Ivrea are of extraordinary dimensions.
That which was on the left bank of the glacier is
about THIRTEEN MILES long, and in some places rises
to a height of TWO THOUSAND ONE HUNDRED AND THIRTY FEET
above the floor of the valley! The terminal moraines
(those which are pushed in front of the glaciers)
cover something like twenty square miles of country.
At the mouth of the Valley of Aosta, the thickness of
the glacier must have been at least TWO THOUSAND feet,
and its width, at that part, FIVE MILES AND A QUARTER."
It is not easy to get at a comprehension of a mass of ice
like that.
