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.
We hear about humidity in just about every weather report on the nightly news. There are several different ways meteorologists measure humidity, but relative humidity is the most common measurement. What is relative humidity, though? Find out in this
So much of our cosmological history starts with the much-discussed big bang, but what led up to that cataclysmic moment? And did time even exist back then?