2.1.4

Weathering

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Weathering

Weathering and erosion constantly attack rocks. Weaker rocks are weathered faster than harder, stronger, more resistant rocks.

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Biological weathering

  • Biological weathering happens when plants or animals break down rocks.
  • For example, trees roots can grow into cracks in rocks and split the rocks apart as the roots grow.
  • Animals can wear rocks down as they burrow into cavities.
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Chemical weathering

  • In chemical weathering, the chemical composition of rock changes.
  • When the climate is warm and wet, carbonic dioxide can dissolve in rain to create a 'carbonic acid'.
  • The carbonic acid in rainfall hits rocks and dissolves the parts of the rock made of calcium carbonate.
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Freeze-thaw weathering

  • Water expands when it freezes.
  • When water fills cracks in rocks, if it then freezes, it expands, putting pressure on the rock.
  • The water will then melt, but it has put pressure on the rock.
  • Eventually, this process of freezing and thawing will wear down the rock until it cracks.
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Onion-skin weathering

  • Onion-skin weathering is when the outer layer separates from the rock.
  • One form of this weathering is exfoliation, where the outer layer of the rock is peeled off by the weather.
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Onion-skin weathering cont.

  • Rocks expand during the day in very hot temperatures and then contract again in the cooler night-time temperatures.
  • This constant movement over thousands of years finally causes the outer layer to peel away.
  • The process then repeats with the next layer.

Jump to other topics

1Geography Skills

2Geology of the UK

3Geography of the World

4Development

5Weather & Climate

6The World of Work

7Natural Resources

8Rivers

9Coasts

10Glaciers

11Tectonics

12Climate Change

13Global Population & Inequality

14Urbanisation

15Ecosystems

16Life in an Emerging Country

17Analysis of Africa

18Analysis of India

19Analysis of the Middle East

20Analysis of Bangladesh

21Analysis of Russia

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