Alluvium (from the Latin, alluvius, from alluere, "to wash against")'s soil or sediments deposited by a river or other running water. Alluvium's typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel. Flowing water associated with glaciers may also deposit alluvium, but deposits directly from ice aren't alluvium (see glacial till). A river's continually picking up and dropping solid particles of rock and soil from its bed t… (More on Alluvial)