Salt freeze?

Frost action, sometimes known as ice crystal growth, ice wedging, frost wedging or freeze-thaw occurs when water in cracks and joints of rocks freeze and expand. In the expansion, it can exert pressures up to 21 megapascals (MPa) (2100 kgf/cm²) at −22 °C. This pressure is often higher than the resistance of most rocks and causes the rock to shatter. This process can be seen in Dartmoor where it results in the formation of tors.