Weathering

Weathering is the process of change, especially decomposition, of rocks and other sediments due to chemical changes. When the changes are due to mechanical processes, it's called erosion.

The first-stage formation of [[cave|caves, when limestone joints are enlarged due to the solution of the calci]]um carbonate in the humic acids in the water, is a kind of weathering. The sub-surface breakdown of rock on hillsides is also a common mode of weathering. Where rock is especially resistant to subsoil weathering, rock outcrops occur, but more often the rock decomposition is taking place unseen due to chemical forces.