• Frost shattering in the Royal Geographical Society Islands in the Canadian Arctic. (Photo: Nick Walker)

[jel-i-frak-shuh n]

Also know as frost shattering, frost wedging or congelifraction, gelifraction is the mechanical fracturing of rock caused by repeated freezing and thawing cycles. Water seeps into pores and cracks in rocks, especially sandstone and shale, where it freezes and expands (by nine per cent), slowly “exploding” its surroundings. This weathering occurs wherever there are freeze-thaw cycles.

From the Latin gelu, meaning “frost” and “icy coldness,” and frangere (fract-), for “break”

Progressively mild winters have led to a decrease in coastal ice along the cliffs of the Îles de la Madeleine, Prince Edward Island and other shores in the Gulf of St. Lawrence. This not only leaves sandstone cliffs more susceptible to the battering of storm waves, it intensifies the natural process of gelifraction, because the coasts are more exposed to the combination of rain and meltwater and sudden freezes.