quality:corruption
Frost

Ice segregation is a less well characterized mechanism of physical weathering. It takes place because ice grains always have a surface layer, often just a few molecules thick, that resembles liquid water more than solid ice, even at temperatures well below the freezing point. This premelted liquid layer has unusual properties, including a strong tendency to draw in water by capillary action from warmer parts of the rock. This results in growth of the ice grain that puts considerable pressure on the surrounding rock, up to ten times greater than is likely with frost wedging. This mechanism is most effective in rock whose temperature averages just below the freezing point, −4 to −15 °C (25 to 5 °F). Ice segregation results in growth of ice needles and ice lenses within fractures in the rock and parallel to the rock surface, which gradually pry the rock apart.