Mechanical Weathering: Freeze-Thaw Action

• Freeze-thaw action


  Also known as frost shattering, occurs when rock breaks up because of repeated freezing of water and thawing of ice in upland areas
• Upland areas


  • Tend to receive more rain than lowland areas
• Freeze-thaw action

  1. Rainwater gathers in the joints (cracks) in rocks

  2. During winter, or whenever the temperature falls below freezing point, this water freezes and expands by about 10%

  3. The expansion of the ice places pressure on the joints in the rock, causing them to widen slightly

  4. When the water thaws, it lies deeper in the joints

  5. The next time the water freezes, the joints widen even more

  6. Over time, the rock breaks and collapses into smaller pieces of rock called scree
• Scree


  • Can be found on the sides of many mountains, such as the Great Sugarloaf in Co. Wicklow