what does illuviation
illuviation (ÉªËluËvÉªËeÉªÊÉn). 1  the process by which a material (illuvium), which includes colloids and mineral salts, is washed down from one layer of soil to a lower layer. Trends. 2  the process by which a material (illuvium), which includes colloids and mineral salts, is washed down from one layer of soil to a lower layer.