Weathering

Weathering

1. Physical weathering

   • Exfoliation / onion skin weathering
     • Occurs in very warm climates
       • This is because the rock is repeatedly heated and cooled.
     • When the rock is heated during the day the outer layers expand.
       • At night it then cools again, causing the layers to contract.
         • This puts strain on the rock. After a while the layers peel of like the skin of an onion.
   • Freeze thaw weathering
     • Water gets into cracks in a rock
       • As the water turns into ice it expands
         • This causes the crack to get bigger
           • When it rains again more water can fill the crack so when it freezes again the crack gets even bigger.
             • Eventualty the rock splits.

2. Biological Weathering

   • Roots of plants & trees get into cracks in rocks
     • As they grow they make the cracks grow bigger too
       • They put pressure on the rock, which can be enough to split it.
   • Animals burrow underneath rock
     • The rock is then left unsuppoted
       • The unsupported rockbreaks

3. Chemical weathering

   • Rainwater is slightly acidic
     • When it comes into contact with rock a chemical reaction takes place.
       • This causes the rock to crumble
   • Water & heat make this proccess faster.