Alluvial_deposit
Alluvium
Loose soil or sediment that is eroded and redeposited in a non-marine setting
Alluvium (from Latin alluvius, from alluere 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings.[1][2][3] Alluvium is also sometimes called alluvial deposit.[4][5] Alluvium is typically geologically young and is not consolidated into solid rock. Sediments deposited underwater, in seas, estuaries, lakes, or ponds, are not described as alluvium.[1]
Floodplain alluvium can be highly fertile, and supported some of the earliest human civilizations.[6]