Rivers As Sculptors of The Land

Out of the hills of Habersham,

Out of the valleys of Hall,

I hurry amain to reach the plain,

Run the rapid and leap the fall,

Split at the rock and together again,

Accept my bed, or narrow or wide,

And flee from folly on every side

With a lover's pain to attain the plain

Far from the hills of Habersham,

Far from the valleys of Hall. 

Song of the Chattahoochee by Sidney Lanier

       The rivers that flow over the land carry great quantities of water to the sea. It would seem that after a while there would be no more water for the rivers. Where do they get so much water that they can flow on and on, year after year?

A river at work.

       The story of water runs around like a circle. It rises as vapor from the sea, to make clouds in the sky. Some of those clouds are blown over the land and from them water again falls to the earth as rain.

       About two-thirds of the rainwater either sinks into the earth or passes back into the air as vapor. The remaining third of that rainwater remains on the surface of the earth, to flow from the higher ground to low places, and eventually become the rivers.

       In the early days of the history of the land, when it first appeared above the level of the sea, there were no mountains nor deep valleys. However, the land was not smooth; it was like a field in which some of the ground is higher than other. When rain fell on the higher ground it ran to the lower ground just as tiny rills run from the high to the low ground in the fields of today.

       The rills that trickle down to lower levels come together to make the brooks and as they come they wash from their pathways tiny bits of rock and soil.

       If the brook flows in a country where mountains are rising it flows very rapidly and can carry a great load of rocks, both rock fragments and the fine debris that comes from the grinding together of the rocks that are being tumbled about in the rushing water. Such a stream cuts down a deeper channel in the rock.

       Brooks come together to make rivers. A young river flows rapidly, carries a great deal of the debris that it gets from the cutting down of its stream bed. Its valley is narrow and its sides are very steep. It continues to cut down its channel until it approaches the level of the sea or the plain toward which it flows. Then it does not flow so rapidly nor wear its channel down to any greater depth.

       The mature river drops much of the rock that it has been carrying. It no longer deepens its channel but it does cut its banks. The valley of the mature river becomes much wider and the steep banks on either side change to gentle slopes, as it follows a crooked pathway to the sea.

       The main current of the mature river tries to flow in a straight line but as it swings around the bends of its crooked channel, it strikes the opposite bank and cuts it away. The slow water at the edge of the current drops mud along the bank on the other side and builds up a flood plain.

       As time goes on the flood plain widens and the river becomes an old meandering stream with an even more crooked channel through its own flood plain.

       Sometimes its pathway is so crooked that it is like loops. If one of the loops is cut off when the river changes its way to flow across the neck of the loop there will be an ox-bow lake that in time may become a swamp. Ox-bow lakes are found only in the region of an old river bed.

       The old river continues its unhurried way on to the sea. It carries millions of tons of soil that has been washed from the land by it and its many contributing branches.

       It might seem that in time the earth would be worn down to be so flat that rivers could no longer do their work, but that never gets to be so. New mountains rise and rivers change their courses and their work continues on and on.

       The face of the earth is never the same from one day to the next. Heat, frost, wind and water are always at work on it. The water that flows over the land as rivers does more than any other one thing to change the appearance of the face of the earth. Thomas

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