cks soften and fall apart. Others are bringing seeds of the
grasses and trees that they may take root in the crumbling rock. It is
their business to make a carpet of plants over the earth and thus stop
my work. But wherever the slopes are steep we rivulets have our way. We
pick up and carry away the particles of sand and clay so that only the
bare, hard rocks remain.

When the steep slopes become gentle, and we can no longer carry away all
the particles of crumbled rock, then the carpet of plants spreads over
the surface. Now our waters become clear. We seem like different
beings. Once in a while, when the rains fall very heavily, some of us
break through the protecting carpet and dig great hollows and gullies
into the earth.

Would you like to know how we rivulets get rid of the load we carry from
the mountain slopes? When we are muddy and swollen with the heavy rains,
we turn the river into a flood. The river then breaks its banks and
spreads out over all the lowlands along its course. Now the river flows
more slowly and drops a part of the sand and mud which we rivulets
brought to it. Finally, when the storm is over and the river goes back
into its channel, there is left on the surface of the valleys a layer of
earth rich in plant food. We brought the river the finest of the rock
particles, together with the leaves and stems of plants that lay in our
way.

[Illustration: _H. W. Fairbanks_
The rivulets have united to form the broad, shallow river loaded with
the soil from the farms along its upper course.]

As year after year we made the river overflow, the soil of the lowlands
grew deeper and deeper until it became as you see it today. Now the
slopes about the head of the river are not so steep as they were once.
Our waters do not run away so rapidly and the river seldom overflows.
Thus the farmer can use the land for his crops, which grow so
luxuriantly that he is envied by his less fortunate neighbors who live
upon the hills.

[Illustration: _U. S. Office of Farm Management_
The soil of this valley has been washed to its present location by flood
waters.]

Upon the slopes about the valleys we rivulets did not leave so much
soil. The farther one goes up the slopes the thinner one finds the soil,
until at the top the bare rock may appear.

But our work, says the muddy rivulet, was not finished with the making
of the fertile valley lands. We carried a part of our load of sand and
mud on to the mo