Paper 1 - Coastal Landscapes In The UK Flashcards
Name two ways rock is broken down
Mechanical and chemical weathering
What’s mechanical weathering?
It’s the breakdown of rock without changing its chemical composition.
Explain and give an example of mechanical weathering
Freeze-thaw weathering -
- It happens when the temp alternates above and below 0
- Water gets into rock that has cracks e.g - granite
- When the water freezes it expands, which puts pressure on the rock.
- When water thaws it contracts, which releases the pressure on the rock.
- Repeated freezing and thawing widens the cracks and causes the rock to break up.
What’s chemical weathering?
It’s the breakdown of rock by changing its chemical composition.
Explain and give an example of chemical weathering?
Carbonating weathering.
- Rainwater has carbon dioxide dissolved in it, which makes it a weak carbonic acid.
- Carbonic acid reacts with rock that contains calcium carbonate, so the rocks are dissolved by the rainwater.
What is mass movement?
Its the shifting of rocks and loose material down a slope.
It happens when the force of gravity acting on a slope is greater than the force supporting it.
What does mass movement cause?
Coasts to retreat rapidly.
What are the three types of mass movement?
Slides
Slumps
Rockfalls
What is a slide?
Material shifts in a straight line.
What is a slump?
Material shifts with a rotation.
What is a rockfall?
Material breaks up and falls down slope.
What are the processes of erosion?
Hydraulic power
Abrasion
Attrition
Corrosion
What is hydraulic action?
Waves crash against rock and compress the air in the cracks. This puts pressure on the rock. Repeated compression widens the cracks and makes bits of rock break off.
What is abrasion?
Eroded particles in the water scrape and rub against rock, removing small pieces.
What is attrition?
Eroded particles in the water smash into each other and break into smaller fragments.
Their edges also get rounded off as they rub together.
What is corrosion?
This is the chemical action of sea water. The acids in the salt water slowly dissolve rocks on the coast.
What are destructive waves?
Waves that carry out erosional processes.
They have a high frequency.
They’re high and steep.
Their backwash is more powerful than their swash = Material is removed form the coast.
How are wave-cut platforms formed?
Waves cause most erosion at the foot of a cliff.
This forms a wave-cut notch, which is enlarged as erosion continues.
The rock above the notch becomes unstable and eventually collapses.
The collapsed material is washed away and a new wave-cut notch starts to form.
Repeated collapsing results in the cliff retreating.
A wave-cut platform is the platform that’s left behind as the cliff retreats.
How are headlands and bays formed?
Soft rock or rock with lots of joints have a low resistance to erosion.
Hard rocks with a solid structure have a high resistance to erosion.
Headlands and bays are when there are alternating bands of resistant and less resistant rock along a coast.
The less resistant rock is eroded quickly and this forms a bay - bays have gentle slopes.
The resistant rock is eroded more slowly and its left jutting out, forming a headland. Headlands have steep sides.
How are caves, arches and stacks formed?
Headlands are usually made of resistant rocks that have weaknesses like cracks.
Waves crash into the headlands and enlarge the cracks - mainly by hydraulic power and abrasion.
Repeated erosion and enlargement of the cracks causes a cave to form.
Continued erosion deepens the cave until it breaks through the headland forming an arch.
Erosion continues to wear away the rock supporting the arch, until it eventually collapses forming a stack.
What is a stack?
An isolated rock that’s separated from the headland.
How is material transported along the coast?
By a process called longshore drift (LSD)
What are the steps of LSD?
- Waves follow the direction of the prevailing (most common) winds.
- They usually hit the coast at an oblique angle (not right angle).
- The swash carries material up the beach, in the same direction as the waves.
- The backwash then carries material down the beach at right angles, back towards the sea.
- Over time the material zigzags along the coast.
What are the processes of of transportation?
LSD Traction Saltation Suspension Solution