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. If
one could cleave off the butt end of such a glacier--an oblong block
two or three miles wide by five and a quarter long and two thousand
feet thick--he could completely hide the city of New York under it,
and Trinity steeple would only stick up into it relatively as far as a
shingle-nail would stick up into the bottom of a Saratoga trunk.

"The boulders from Mont Blanc, upon the plain below Ivrea, assure us
that the glacier which transported them existed for a prodigious length
of time. Their present distance from the cliffs from which they were
derived is about 420,000 feet, and if we assume that they traveled at
the rate of 400 feet per annum, their journey must have occupied them no
less than 1,055 years! In all probability they did not travel so fast."

Glaciers are sometimes hurried out of their characteristic snail-pace.
A marvelous spectacle is presented then. Mr. Whymper refers to a case
which occurred in Iceland in 1721:

"It seems that in the neighborhood of the mountain Kotlugja, large
bodies of water formed underneath, or within the glaciers (either on
account of the interior heat of the earth, or from other causes), and at
length acquired irresistible power, tore the glaciers from their mooring
on the land, and swept them over every obstacle into the sea. Prodigious
masses of ice were thus borne for a distance of about ten miles over
land in the space of a few hours; and their bulk was so enormous that
they covered the sea for seven miles from the shore, and remained
aground in six hundred feet of water! The denudation of the land was
upon a grand scale. All superficial accumulations were swept away, and
the bedrock was exposed. It was described, i