alluvium
/əˈluːviəm/ (bre, ipa) · /əˈluːviəm/ (ame, ipa) · /ə-ˈlü-vē-əm/ (ame, mw)
alluvium — noun
1. A layer or deposit of soil, mud, sand, gravel, and similar material that flowing
A layer or deposit of soil, mud, sand, gravel, and similar material that flowing water — such as a river or flood — carries and then drops onto land, often making the ground rich for growing crops.
The annual flood left a rich layer of dark alluvium across the Watanabe family's rice fields.
collocation: rich alluvium
Dr. Okafor discovered layers of ancient alluvium while digging near the river bank.
The soil in this valley is mainly alluvium washed down from the mountains by the river.
After the storm, dark alluvium covered the farmland close to the mouth of the river.
The fertile alluvium in the Nile Valley has supported farming communities for thousands of years.
- sediment
Broader term; includes material deposited by wind, ice, or water, not only rivers.
- silt
Narrower; refers specifically to fine, dust-like particles, not gravel or sand.
- deposit
General term for any natural material left by a process; less specific than alluvium.
- loam
Refers to a mix of sand, silt, and clay in soil; alluvium can become loam but is not the same.
文法句型
alluvium + verb (deposit, form, cover)
adjective + alluvium (rich, fertile, ancient)
用法筆記
This term is most common in geography, geology, and farming contexts. It is typically uncountable ("the alluvium"), but some scientific writing uses alluviums or alluvia when referring to multiple distinct deposits or types.