Fluvial terrace

They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplain, other fluvial terraces, or uplands by distinctly steeper strips of land called "risers".

Terraces can also be left behind when the volume of the fluvial flow declines due to changes in climate, typical of areas which were covered by ice during periods of glaciation, and their adjacent drainage basins.

The valley may fill with alluvium for many different reasons including: an influx in bed load due to glaciation or change in stream power which causes the valley, that was down cut by either a stream or river, to be filled in with material (Easterbrook).

The fill terrace is created when the conditions change again and either a stream or river starts to incise into the material that it deposited in the valley.

As either a stream or river continues to incise into the material, multiple levels of terraces may form.

These terraces are depositional in origin and may be able to be identified by a sudden change in alluvium characteristics such as finer material.

Once downcutting continues the flattened valley bottom composed of bedrock (overlain with a possible thin layer of alluvium) is left above either a stream or river channel.

Using the resulting date and the elevation above its current level, an approximate average rate of downcutting can be determined.