Why does freezing break up rock? Everybody knows that when water freezes it expands by nine percent to be precise. If it seeps into rocks and then freezes, the rocks can fracture and split apart, a process known as frost weathering. So far so logical. But this long-held explanation is probably not very significant in nature because it requires some pretty unusual conditions. The rock must essentially be water-saturated and frozen from all sides, to prevent the piston-like effect of freezing water driving the remaining liquid water into empty spaces or out of the rock through an unfrozen side or crack. So we need to look for another explanation
