(Physical: Ice creating Pressure)
Girraween is a cold place in winter and it is subjected to repeated frosts and sometimes even snow. Water caught in cracks of the granite will freeze, and when it does so, it expands in size by about 9%. This puts pressure on the rock and causes the cracks to slightly deepen and widen. When the ice melts, the water from it can then flow a little further into the rock. When it freezes again, the swollen ice stresses the rock again and forces the crack apart just a little bit more. Repeated freeze-thaw action will weaken the granite which, over time, will eventually break apart along the crack.
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Large ice crystals can be easily seen here spreading across the water.
Unseen tiny ice crystals form in cracks in the rock, stressing the granite
and ultimately breaking it apart.
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Next...
Kaolinisation – Dissolving granite. How can this happen?
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