Fluvial Terrace

Fluvial terraces are elongated terraces flanking the sides of floodplains and river valleys worldwide, each consisting of a relatively level strip of land called a tread, separated from an adjacent floodplain, other terraces or the surrounding uplands by steeper strips called risers. Lying parallel to and above the river channel, a fluvial terrace is underlain by fluvial sediment of variable thickness and represents the remnant of an earlier floodplain that existed when the stream or river flowed at a higher elevation, before its channel cut downward to create a new floodplain below; this downcutting can result from a change in the fluvial system's base level or from a decline in flow volume caused by climate change, such as in areas once covered by glacial ice.