, they move
rapidly; at least in times when the torrent is raging. They beat over
each other and against the firm-set rocks; the more they wear, the
smaller they become, and the more readily they are urged forward.
Where the masses are too large to be stirred by the violent current,
they lie unmoved until the pounding of the rolling stones reduces them
to the proportions where they may join the great procession.
Ordinarily those who visit mountains behold their torrents only in
their shrunken state, when the waters stir no stones, and fail even to
bear a charge of mud, all detachable materials having been swept away
when the streams course with more vigour. In storm seasons the
conditions are quite otherwise; then the swollen torrents, their
waters filled with clay and sand, bear with them great quantities of
boulders, the collisions of which are audible above the muffled roar
of the waters, attesting the very great energy of the action.

When the waste on a mountain slope lies at a steep angle, particularly
where the accumulation is due to the action of ancient glaciers, it
not infrequently happens that when the ground is softened with frost
great masses of the material rush down the slope in the manner of
landslides. The observer readily notes that in many mountain regions,
as, for instance, in the White Mountains of New Hampshire, the steep
slopes are often seamed by the paths of these great landslides. Their
movement, indeed, is often begun by sliding snow, which gives an
impulse to the rocks and earth which it encounters in its descent. At
a place known as the Wylie Notch, in the White Mountains, in the early
part of this century, a family of that name was buried beneath a mass
of glacial waste which had hung on the mountain slope from the ancient
days until a heavy rain, following on a period of thaw, impelled the
mass down the slope. Although there have been few such catastrophes
noted in this country, it is because our mountains have not been much
dwelt in. As they become thickly inhabited as the Alps are, men are
sure to suffer from these accidents.

As the volume of a mountain torrent increases through the junction of
many tributaries, the energy of its moving waters becomes sufficient
to sweep away the fragments which come to its bed. Before this stage
is attained the stream rarely touches the solid under rock of the
mountain, the base of the current resting upon the larger loose stones
which it was unable