Sediment is dislodged from the land by the pounding action of raindrops and the flow of runoff, and sometimes is washed from streambanks during high flows--which may themselves be higher and more frequent because of silt-clogged channels. The bulk of it can be blamed on unsound land use. This may be rural, based in the old use-her-up-and-move-along pioneer outlook that has never died out among us despite wide understanding of better ways of doing things. People in places still overgraze pastures and clean-cut timber so that rain can get at the soil and eat it away, and they still farm land too steep to stay in place without its vegetative cover, or they plow even suitable rolling land in straight rows up and down hill so that water and soil sluice away together down the furrows when it rains. Despite a sharply effective three decades of work and public education by the Soil Conservation Service and other agencies, these old practices continue in some places and cause much erosion. [Illustration] Also, increasingly, bad land use involves the ways in which great machines adapt the landscape to hundreds of sophisticated purposes. The massive eatings of powered blades and scoops to get at coal and other minerals on the steep slopes of the North Branch watershed and elsewhere, add heavily to sedimentation. So do broad rights-of-way gashed out of the countryside and left bare under storms in the months before highway construction is done, and secondary roads that even when finished may be left for years or forever with denuded clay shoulders and ditches and banks that wash with every rain. And so, most particularly, do the great polygons of rolling land around the Basin's town and cities that are stripped naked by bulldozers and left sitting in that condition for long periods, while they await the erection of buildings and blocks of homes. This is occurring throughout the Basin, but most notably around Washington, where the highest erosion rates of all are found. We will take a look at its details and the reasons for it a little further along in this chapter when we examine the estuary's situation.