Comminution
From Glossary of Meteorology
comminution
The reduction of stone to small particles through any natural action such as frost action (crevices formed through alternate freezing and thawing); biochemical action of plants, trees, and organisms growing in rocks; wind corrosion (a natural phenomenon akin to sand blasting); ocean wave action; glacial scouring; and tectonic action (the shearing and jointing of rocks caused by stresses in the earth's crust).