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