Denudation

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Denudation
Lesson Plan
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What is denudation?

• The shaping of the earth

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What shapes the land?
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Denudation processes

• Weathering
• erosion
• mass wasting/ mass movement

What are they?
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What is weathering?
Processes leading to disintegration and
decomposition of rock
in situ processes
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How does the rock break up?

• 1. Mechanical weathering/ Physical weathering
• 2. Chemical weathering
• 3. Biotic / Biological weathering

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Mechanical weathering

• Caused by
• temperature changes
• unloading brought about by denudation
• salt crystal growth

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Block Disintegration
With repeated expansion and contraction, the rock
breaks up along joints
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A Disintegrated block
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Exfoliation
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Rock peels off
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Granular disintegration
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Chemical weathering

• Decomposition of rock caused by rain, air (e.g.
  Carbon dioxide) and organic acids.
• Active in hot and wet areas

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What Chemical Processes?

• Solution
• Hydration
• Hydrolysis
• Oxidation
• Carbonation

How do they act on rock?
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Honeycomb weathering
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They are always found near the coast. Why?
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Spheroidal weathering
Partially weathered core-stone
Totally weathered outer layer
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Biotic/ Biological Weathering

• Physical break up of rock by plant roots or
  burrowing animals
• Chemical decay of rock facilitated by organic
  acid produced by plants and animals

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Weathered granite in HK