The history of sediment and its movement in the Atlantic drainage demonstrate some of the difficulties of modeling sediment on a river-basin scale. Soil erosion was accelerated by a factor of at least 10 when European settlers cleared forests and planted crops. Large quantities of eroded material are still stored on hillslopes and in stream valleys where they continue to augment the sediment loads of the rivers. This sediment will emerge from storage for many decades. The reservoirs that have been built on many of the major rivers trap significant portions of the moving sediment. Essentially all the river sediment that reaches the Atlantic coastal zone is trapped in estuaries and coastal marshlands. -from Author