the business of some of the servants of Nature, as we have already
learned, to tear down the mountains and fill up the hollows in the
earth. It is the business of others to spread a carpet of vegetation
over the surface, and wherever they have already succeeded in their work
the waters run clear most of the time.

Where it is dry so much of the time that few plants can live, the
destructive servants have their own way when the occasional rains come.
Where there is a warm sun and frequent rains, a green carpet is spread
over all the slopes. But when men destroy the carpet and take no care of
the soil underneath, the raindrops are able to do as much damage as they
do during the cloudbursts in the deserts.

The Colorado is one of those rivers in the basin of which few people
live. Much of its journey is through a land in which there is little
vegetation. Here, the waters from the melting snows upon the lofty
mountains about the basin and those of the occasional heavy rains have
things their own way. They are always yellow with mud. The amount of mud
which this river carries has been measured. You will hardly believe me
when I tell you that it amounts to sixty-one million tons every year.
This is enough to cover 164 square miles one foot deep. We might call
this the cream of the soil from all the slopes of the great basin of the
Colorado River.

In other parts of our land, where abundant rains fall, the streams tell
a different story. Before men came the water of these streams was clear
throughout the greater part of the year. It was only when the rains were
very heavy that the soil washed away, for the vegetation held it well.
Now the gullies on the hillsides and along the roads tell us as plainly
as though they could speak that our country is losing wealth here.

[Illustration: _H. W. Fairbanks_
The roots of the tree form a wonderful network underground from which
the water cannot tear the soil.]

The soil is our most valuable possession. The people of many lands are
suffering from poverty today because their forefathers did not take care
of the soil as they should. In such lands the people who live on the
mountain sides are poor, because the best of their soil has been washed
away. Those who live in the valleys are often poor because of the sands
and gravels which floods have spread over their fertile fields.

While it is raining, let us fill a bottle from some muddy stream and
allow it to stand until the w