Unit 3 Physical Landscapes in the UK - Coasts Flashcards
What is weathering?
The breakdown of rocks where they are
What is erosion?
When rocks are broken down and carried away by something
What is mechanical weathering?
The breakdown of rock being disintegrated rather than decomposed
Give an example of mechanical weathering
Freeze-thaw weathering
Explain freeze-thaw weathering
- It happens when the temperature alternates above and below 0°C
- Water enters rock that has cracks (e.g. granite)
- When the water freezes, it expands, which puts pressure on the rock
- When the water thaws, it contracts, which releases the pressure on the rock
- Repeating freezing and thawing widens the cracks and causes the rock to break up
What is chemical weathering?
Caused by a chemical reaction when rainwater hits rock and decomposes it or eats it away
Give an example of chemical weathering
Carbonation weathering
When does carbonation weathering happen? (type of chemical weathering)
In warm and wet conditions
Explain carbonation weathering
- Rainwater has carbon dioxide dissolved in it, which makes it a weak carbonic acid
- Carbonic acid reacts with rock that contains calcium carbonate (e.g. carboniferous limestone), so the rocks are dissolved by the rainwater
What is mass movement?
The shifting of rocks and loose material down a slope (e.g. a cliff)
When does mass movement happen?
When the force of gravity acting on a slope is greater than the force supporting it
How does mass movement affect coasts?
It causes coasts to retreat rapidly
When is mass movement most likely to happen?
When the material is full of water - water acts as a lubricant, and makes the material heavier
What does the shifting of material create on a slope? (mass movement)
A scarp (a steep ‘cut’ in the side of the slope)
What is a landslide?
When large blocks of rock slide downhill
How does a landslide occur?
A wave-cut-notch is created and as it grows bigger, the weight of the cliff becomes to much to support, causing a landslide
What is a rockfall?
When bits of rock fall off the cliff face