In geomorphology, what are alluvial deposits?

Alluvial deposits refer to the material that is sorted and deposited by the action of flowing water, typically in river environments. These deposits often consist of sediments such as sand, silt, clay, and gravel, which are carried and eventually dropped when the velocity of the water decreases. This process commonly occurs in floodplains, riverbanks, and deltas, where rivers slow down and spread out. The characteristic feature of alluvial deposits is that they are formed through the sediment transport and deposition processes associated with moving water, making them critical in understanding river dynamics and landscape formation in river valleys.

While glacial activity produces distinct deposits known as till, volcanic eruptions result in different types of geological deposits such as ash and lava flows, and wind erosion mainly leads to aeolian deposits, none of these processes involve the movement and sorting of sediments by water, which is the defining characteristic of alluvial deposits.