What state of things, then, do we find among the highest
mountains; and over whole countries which, though not lofty, lie far
enough north or south to be permanently covered with ice?
We find, first, an ice-cap or ice-sheet, fed by the winter's snows,
stretching over the higher land, and crawling downward and outward by
its own weight, along the valleys, as glaciers.
We find underneath the glaciers, first a moraine profonde, consisting
of the boulders and gravel, and earth, which the glacier has ground
off the hillsides, and is carrying down with it.
These stones, of course, grind, scratch, and polish each other; and
in like wise grind, scratch, and polish the rock over which they
pass, under the enormous weight of the superincumbent ice.
We find also, issuing from under each glacier a stream, carrying the
finest mud, the result of the grinding of the boulders against each
other and the glacier.
We find, moreover, on the surface of the glaciers, moraines
superieures--long lines of stones and dirt which had fallen from
neighbouring cliffs, and are now travelling downward with the
glaciers.
Their fate, if the glacier ends on land, is what was to be expected.
The stones from above the glacier fall over the ice-cliff at its end,
to mingle with those thrown out from underneath the glacier, and form
huge banks of boulders, called terminal moraines, while the mud runs
off, as all who have seen glaciers know, in a turbid torrent.
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