Mechanical Processes

• Freeze-Thaw


  Water penetrates joints, bedding planes, cleavages, faults and pore spaces

  Temp falls and water turns to Ice - Ice occupies a greater volume than water

  Creates stress

  Process repeats leading to angular fragmenrs fracturing off
• Onion Skin Weathering


  Common in areas with large temp. ranges

  Outer layer of rock heats up and expands more rapidly than deeper layers during the day

  At night, outer layers cool and contract more

  A series of fractures causes the rock to peel off in layers like an onion
• Pressure Release


  Rocks at depth under great pressure

  Erosion removes overlying material

  Removal of mass causes rock to expand parallel to its own surface

  Rock fractures to from horizontal joints