An alluvial deposit is an accumulation of alluvium (sediment), sometimes containing valuable ore and gemstones, or simply consisting of gravel, sand, or clay, in the bed or former bed of a river. Valuable materials such as gold may be extracted using techniques of placer mining. Historically, gemstones (diamonds in particular), were found in the gravels of India. They continue to be mined from alluvium in Myanmar and Sri Lanka. Glacial deposits known as till are not alluvium, as they are deposited directly by glaciers, but till is often reworked by streams to produce alluvial deposits.

See also

• Alluvial fan
• Alluvial plain
• Eluvial deposits

Аллювий | 沖積層

Sedimentology