which is the widening of cracks or joints in rocks resulting from the expansion of porewater when it freezes. A growing body of theoretical and experimental work suggests that ice segregation, whereby supercooled water migrates to lenses of ice forming within the rock, is the more important mechanism.

When water freezes, its volume increases by 9.2%. This expansion can theoretically generate pressures greater than 200 MPa, though a more realistic upper limit is 14 MPa. This is still much greater than the tensile strength of granite, which