good stout wall to batter, whereas in places where the ground is
soft it washes down into a gradual gentle slope, and so the
waves come flowing smoothly in and have no power to eat away the
shore.

And now, what has Ice got to do with the sculpturing of the land?
First, we must remember how much the frost does in breaking up
the ground. The farmers know this, and always plough after a
frost, because the moisture, freezing in the ground, has broken
up the clods, and done half their work for them.

But this is not the chief work of ice. You will remember how we
learnt in our last lecture that snow, when it falls on the
mountains, gradually slides down into the valleys, and is pressed
together by the gathering snow behind until it becomes moulded
into a solid river of ice (see Fig. 29, Frontispiece). In
Greenland and in Norway there are enormous ice-rivers or glaciers,
and even in Switzerland some of them are very large. The Aletsch
glacier, in the Alps, is fifteen miles long, and some are even
longer than this. They move very slowly - on an average about 20
to 27 inches in the centre, and 13 to 19 inches at the sides every
twenty-four hours, in the summer and autumn. How they move, we
cannot stop to discuss now; but if you will take a slab of thin
ice and rest it upon its two ends only, you can prove to yourself
that ice does bend, for in a few hours you will find that its own
weight has drawn it down in the centre, so as to form a curve.
This will help you to picture to yourselves how glaciers can adapt
themselves to the windings of the valley, creeping slowly onwards
until they come down to a point where the air is warm enough to
melt them, and then the ice flows away in a stream of water. It is