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overbank

a. (context geology English) Describing sediments deposited on a floodplain from suspensions in floodwaters

Wikipedia
Overbank

An overbank is an alluvial geological deposit consisting of sediment that has been deposited on the floodplain of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in suspension, and because it is carried outside of the main channel, away from faster flow, the sediment is typically fine-grained. An overbank deposit usually consists primarily of fine sand, silt and clay. Overbank deposits can be beneficial because they refresh valley soils.

Overbank deposits can also be referred to as floodplain deposits. Examples include natural levees and crevasse splays.

Usage examples of "overbank".

He overbanked and the plane lost altitude precipitously, threatening to strike Toad straddling the roof's ridge.