Alluvium, the silt, clay, sand, and other material transported and deposited by running water. The term excludes lake and ocean deposits and is usually restricted to geologically recent sediments. Alluvium is laid down in many places but occurs most extensively on flood plains (areas along streams that are subjected to flooding); in river deltas; and in alluvial fans, cones, and plains at the base of steep mountains. Some of the world's richest agricultural land consists of alluvial soil. Such regions are also among the most heavily populated on earth. Examples include the Nile River valley and the deltas of eastern and southeastern Asia.
He was born exactly 300 years after Galileo died. He has yet to be awarded a Nobel Prize, although he was awarded a guest spot on “The Simpsons.” What else do you know (or not know) about this acclaimed physicist?
So much about galaxies remains a mystery. We know what they're made of and that we live in one (the Milky Way), but we're not sure how they form and evolve.