rent swings to one side of the channel, lifting the
loose sediment and grinding deeper the bed of the stream. The water lags
on the opposite side, and sediment falls to the bottom. So the
building-up of one side is going on at the same time that the
tearing-down process is being carried on on the other. With the lowering
of the bed the river swerves toward one bank, and a hollow is worn by
slow degrees. The current swings into this hollow, and in passing out is
thrown across the stream to the opposite bank. Here its force wears away
another hollow; and so it zigzags down-stream. The deeper the hollows,
the more curved becomes the course, if the general fall is but moderate.
It is toward the lower courses of the stream that the winding becomes
more noticeable. The sediment that is carried is deposited at the point
where the current is least strong, so that while the outcurves become
sharper by the tearing away of the stream's bank, the incurves become
sharper by the building up of this bank.

The Mississippi below Memphis is thrown into a wonderful series of
curves by the erosion and the deposit caused by the current zigzagging
back and forth from one bank to the other. Gradually the curves become
loops. The river's current finally jumps across the meeting of the
curves, and abandons the circular bend. It becomes a bayou or lagoon of
still water, while the current flows on in the straightened channel.
All rivers that flow through flat, swampy land show these intricate
winding channels and many lagoons that have once been curves of the
river.

No one would ever mistake a river for a lake or any other body of water,
yet rivers differ greatly in character. One tears its way along down its
steep, rock-encumbered channel between walls that rise as vertical
precipices on both sides. The roaming, angry waters are drawn into
whirlpools in one place. They lie stagnant as if sulking in another,
then leap boisterously over ledges of rock and are churned into creamy
foam at the bottom. Outside the mountainous part of its course this same
river flows broad and calm through a mud-banked channel, cut by
tributary streams that draw in the water of low, sloping hills.

The Missouri is such a wild mountain stream at its headwaters. We who
have seen its muddy waters from Sioux City to St. Louis would hardly
believe that its impetuous and picturesque youth could merge into an old
age so comfortable and placid and commonplace.

This thin