flood plain

At Little Falls, Minn., flood-plain, deposits of sand and gravel are found to contain many artificial objects of quartz.

Those using the slough are almost certainly permanent inhabitants of the river flood plain.

In times of flood they are carried far away from the regular channel and spread over the wide flood-plain of the river.

The extension seaward of this flood plain forms the broad delta at the river's mouth.

Along its lower course “the flood plain is bordered by high bluffs of yellow sandstone.”