Chemical weathering of rock and sediment minerals and the leaching out (loss) of the more soluble parts produces soils.
The first-stage formation of caves, when limestone joints are enlarged due to the solution of the calcium carbonate, by the inorganic and 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.