alluvium

Salt River, Arizona.
Credit: Sharon Reynolds, Arizona State University

Material such as gravel, sand, silt, or clay deposited, mainly near their mouths, by streams and rivers. Alluvium makes rich agricultural soil, and the earliest civilizations originated as farming communities centered on alluvial flood plains. All rivers have some alluvium deposits, but large rivers such as the Mississippi or Amazon have alluvial plains which are several kilometers wide. See also alluvial fan.

Related category

• GEOLOGY AND PLANETARY SCIENCE

Source: U.S. Geological Survey

Also on this site:

Encyclopedia of Alternative Energy & Sustainable Living
Encyclopedia of History

BACK TO TOP