Eduqas A-Level Geography A110QS
Coastal LandscapesLandscape
Glaciated LandscapesLandscape
Changing Places
Water and Carbon Cycles
Global Migration
Global Governance of the Oceans
Tectonic Hazards
EcosystemsContemporary theme
Economic Growth and Challenge: IndiaContemporary theme
Economic Growth and Challenge: ChinaContemporary theme
Development in an African ContextContemporary theme
Energy Challenges and DilemmasContemporary theme
Weather and ClimateContemporary theme
Geographical Skills
Coastal Landscapes
Sub-aerial weathering and mass movement at the coast
- 2 things to know
- Component 1 Section A
Overview
Sub-aerial processes, how freeze-thaw weathering attacks a cliff and wetting and drying weathering and where does it matter most.
What you need to know
Answer each one before you reveal it.
Explain how freeze-thaw weathering attacks a cliff.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define sub-aerial processes.
Model answer
Sub-aerial processes are those that act on a cliff face above the waterline. Weathering and mass movement are the two groups.
- 2
Explain how freeze-thaw weathering attacks a cliff.
Model answer
Water in a joint freezes and expands by about 9%, forcing the crack wider. Repeated cycles around 0 °C shatter the rock into angular fragments.
- 3
How does salt crystallisation weather a coastal cliff?
Model answer
Sea spray soaks into pore spaces in the rock and then evaporates. Salt crystals grow in the pores and the pressure they exert prises grains apart.
- 4
What is wetting and drying weathering and where does it matter most?
Model answer
Clays expand when wet and contract when dry, and the repeated movement breaks the rock down. Clay cliffs such as those at Barton on Sea are especially affected.
- 5
Explain the chemical weathering process of carbonation.
Model answer
Rainwater absorbs carbon dioxide and forms weak carbonic acid. The acid reacts with calcium carbonate in limestone and chalk to make soluble calcium bicarbonate.
- 6
Describe the process of hydrolysis on a granite cliff.
Model answer
Hydrogen ions in slightly acidic water react with feldspar minerals in the granite. Feldspar is converted to clay, so the rock crumbles and loses strength.
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