Forest devastation, and wastage by erosion is not restricted to the uplands of America. Millions of acres of formerly productive alluvial land along streams have been seriously impaired or ruined by the deposition of inert sand and gravel. Channel-ways have been choked to overflowing by sediments washed from bare slopes that never should have been cleared. Not only this, but the reservoirs of costly waterpower projects are silting up at a rapid rate, so that the power generated must depend more and more upon stream flow, without much assistance from water stored for time of drought. In various parts of the country streams that formerly were navigable have become so choked with sediment that their channels have become obliterated or split into several channels too shallow and small to carry the increased floods from the cleared uplands.

The Coldwater River of Mississippi, for example, was regularly ascended about forty years ago by boats of large size. These boats loaded cotton at the town of Coldwater. Now mudflats and sandbars keep riverboats from this stream. A large, productive cotton plantation just below Coldwater has been abandoned, and the fields are grown over with thickets of willow and cottonwood. In our farming operations we have made use of lands too steep for cultivation, with little or no regard for what would happen to the soil under the influence of beating rainstorms.

Some well-known types of soil, such as the Cecil clay loam of the Piedmont, the Memphis silt loams of the Missouri and lower Mississippi Valleys, and the Cincinnati silt loam of the belt of hills bordering the Ohio River, are so susceptible to erosion that these lands gully, or even melt away like sugar when, on slopes of only moderate steepness, they are used for the inter-tilled crops. Notwithstanding this common knowledge, practically all of these lands have been cleared and put into cultivation, with no terraces to protect them from erosion, except in the southern Piedmont section. As a result thousands of farms have been cut to pieces by gullies, and have been shorn of the fertile topsoil by sheet erosion.

In the central part of the Appalachian system a survey showed that fifty per cent of all the cleared land had been seriously damaged by erosion. In some fields where the stumps of the removed forest had not completely disappeared the surface soil had been washed off and "poverty grass" was driving out the more valuable bluegrass. On the steeper slopes of the older fields, now abandoned, practically all of the soil had been removed down to bed rock, even where the virgin soil averaged nearly eighteen inches in depth, as a few remaining patches of the original timber showed it once had.