Fill a jar with water.  Put in a handful of mud from the nearest stream.  Shake the jar, and the water is muddy.  Let it stand awhile.  What do you notice?  The water is clear, and the soil has settled to the bottom.

Follow the streams to the valley where they unite to form a river.  When does the load of mud it carries settle?  Here, where the water scarcely moves, we find some of the soil spread out over the ground near the river banks.

You have seen a river overflow its banks.  When the water went down, it left a layer of rich mud, which made the soil very fertile.

[Illustration:  “THESE FERTILE MEADOWS WERE FORMED OUT OF THE LOAM.”]

Have you never seen the low ground on the banks of rivers covered with rich grass and clover?

Well, these fertile meadows were formed out of the loam that has been washed down the streams from the far-off hills and mountains.

Look at the jar again.  Which settled first, the coarse material or fine loam?  What kind of a deposit will be made in the upper course of a river?  What kind toward the mouth?

High up in the valley, when the river is low, we see pebbles in its bed; lower down, the pebbles are worn into gravel; and as we get still farther down, we find the gravel ground into sand.

Examine the stones found along the shore of a brook or river.  Some are quite smooth and round.  They were not always so, but had sharp edges.  Do you know what made them round?

When there are heavy rains, the rushing water sweeps large stones down the mountain side and into the valley.  As they are carried down the stream, the stones, by rubbing against each other, are smoothed and rounded and ground into pebbles.  The pebbles themselves are ground at last into gravel and fine sand.

This is what the streams are doing everywhere—­plowing deep furrows in the sides of the mountains, grinding the pebbles and sand into fine soil, and carrying it into the valleys below.

LESSON XXII.

WATERDROP’S STORY.

Patter, patter, fall the raindrops on the brown leaves in the woods.  Mr. Squirrel’s bright eyes sparkle as he peeps out of his queer little home, a hole in the tree; his store of nuts has been carefully hidden away.

Splash comes a drop on a leaf just opposite him.  Such a friendly little drop it is, for soon it tells this little woodland dweller of all its travels.

Let us listen, for we may hear too: 

“My home,” began the Waterdrop, “is in the wide blue sea, where I live with many, many other drops.

“One day as we rode up and down on the big waves, the sun shone down on us, and we grew warmer.  Each little drop felt, ’Oh, if I could only get away from the other drops, how much cooler I should be!’ Then each tiny drop separated from the others, and grew so small you could not see it.