Overbank

The disturbance of adjacent environments during flooding events leads to deposits containing terrestrial organic debris such as plant matter, and the intervening dry periods allow subaerial bioturbation by roots and burrowing animals.

[4] Levees tend to be steeper when they first form and are close to the channel, then gradually level out as they grow and their grain size decreases.

[6] In the stratigraphic record, natural-levee deposits typically consist of thinly-layered sandstones overlying mud- to clay-sized beds.

[5] These crevasse channels are essentially miniature distributary systems and can have many of the features that larger fluvial bodies possess, like levees.

[4] Crevasse channels are ephemeral, and their deposits commonly show terrestrial or desiccation features near the top such as mudcracks or roots.

[4] Tectonism can also affect the fluvial system by altering relative sea level, exposing floodplains or covering new areas with overbank deposits.