Athro, Limited Earth Science K-T Field Trip

Meandering streams cut a channel into a flood plain and deposit several characteristic sediments. Most notable of these are 1) channel fill sediments left by point bars that are deposited in the slowly moving water on the inside of bends and 2) the overbank deposits. Ovebank deposits are primaraly soils developed in fine grained sediments draped on the floodplain during floods. Examples of point bars at several scales are shown below.

A point bar in a small creek in Alabama.

A point bar in a meandering stream in Yellowstone.

An aerial view of a point bar produced by late Pleistocene floods in the Columbia River in Washington.

Both Paleocene and Late Cretaceous sediments in Eastern Montana are composed of sediments derived from meandering rivers. They are composed of crossbedded sand bodies (channel fill) that cut into fine grained sediments with variously developed paleosols.

You may return to a view of the Iridium hill area, or click anywhere on the section at right to explore further.