t refracts, taking
direction again for the other side. Above the Missouri, the river is
principally directed by the natural trough of the valley. Below this,
however, the channel is purely the work of the river itself, shaped
according to the necessities of sudden changes or obstructions. This is
proven by the large number of old and dry beds of the river frequently
met with, the channel having been diverted in a new direction by the
accumulation of sediment and drift which it had not the momentum to
force out.

Where the gravity of the greatest volume and momentum of water falls
upon the bed of the river, there is described the thread of the channel,
and all submerged space outside of this, though in the river, acts as a
kind of reservoir, where eddies the surplus water until taken up by the
current. And it always happens, where the channel takes one bend of the
bed, a corresponding tongue of shallow water faces the indenture. Where
the river, by some inexplicable cause, has been thrown from its regular
channel, or its volume of water embarrassed by some difficulties along
the banks, the effect is immediately perceived upon the neighboring
bank. The column of water thus impinged against it at once acts upon the
bank, and, singularly enough, exerts its strongest abrasive action at
the bottom, undermining the bank, which soon gives way, and instead of
toppling forward, it noiselessly slides beneath the water and
disappears. Acres of land have thus been carried away in an incredibly
short time, and without the slightest disruption of the serene flow of
the mighty current.

This carrying away of the banks, immense as is the amount of earth
thrown into the waters of the river, has no sensible effect in blocking
or directing the current, though it imperceptibly raises the channel.
The force of the water does not permit its entire settlement in
quantities at any one place, but distributes it along the bottom and
shores below. Were this not the case, it is easily to be seen, the
abrasion of the river banks would be greatly increased, and the
destruction of the bordering lands immense.

A singular feature resulting from the above may here be mentioned. By
pursuing the course of the river, a short distance below, on the
opposite bank, it will be seen that a large quantity of the earth
introduced into the current by the falling of the banks, has been thrown
up in large masses, forming new land, which, in a few seasons, becomes