uessed the riddle of the boulders. The rich soil
of the Northern States is the glacial drift--the mixture of rock
fragments of all sizes with fine boulder clay, left by the gradual
melting of the great ice-sheet as it retreated northward at the end of
the "Glacial Epoch."

GLACIERS AMONG THE ALPS

Switzerland is a little country without any seacoast, mountainous, with
steep, lofty peaks, and narrow valleys. The climate is cool and moist,
and snow falls the year round on the mountain slopes. A snow-cap covers
the lower peaks and ridges. Above the level of nine thousand feet the
bare peaks rise into a dry atmosphere; but below this altitude, and
above the six thousand-foot mark, lies the belt of greatest snowfall.
Peaks between six and nine thousand feet high are buried under the
Alpine snow-field, which adds thickness with each storm, and is drained
away to feed the rushing mountain streams in the lower valleys.

The snow that falls on the steep, smooth slope clings at first; but as
the thickness and the weight of these snow banks increase, their hold on
the slope weakens. They may slip off, at any moment. The village at the
foot of the slope is in danger of being buried under a snow-slide, which
people call an avalanche. "Challanche" is another name for it. The
hunter on the snow-clad mountains dares not shout for fear that his
voice, reechoing among the silent mountains, may start an avalanche on
its deadly plunge into the valley.

On the surface of the snow-field, light snow-flakes rest. Under them the
snow is packed closer. Deeper down, the snow is granular, like pellets
of ice; and still under this is ice, made of snow under pressure. The
weight of the accumulated snow presses the underlying ice out into the
valleys. These streams are the glaciers--rivers of ice.

The glaciers of the Alps vary in length from five to fifteen miles, from
one to three miles in width, and from two hundred to six hundred feet in
thickness. They flow at the rate of from one to three feet a day, going
faster on the steeper slopes.

It is hard to believe that any substance as solid and brittle as ice can
flow. Its movement is like that of stiff molasses, or wax, or pitch. The
tremendous pressure of the snow-field pushes the mass of ice out into
the valleys, and its own weight, combined with the constant pressure
from behind, keeps it moving.

The glacier's progress is hindered by the uneven walls and bed of the
valley, and b