The New Student's Reference Work/Flood-Plains

Flood-Plains are level tracts of land which have been formed by the sediment deposited by a river when in flood. The flood-plains of the Nile, the Mississippi, the Po and other rivers are of great extent and very fertile. Frequently the course of a river changes by a gradual swing to one side, owing to the settling of sediment in its own channel, and in this way a delta of flood-plains is apt to be formed, as in the case of the Nile and the Mississippi, at its mouth.