Coasts (4) Flashcards
Name the different types of Weathering processes?
Biological
Mechanical
Chemical
What is Mechanical Weathering?
The breakdown of rock without changing it’s chemical composition
-mainly salt weathering:
-seawater gets into cracks, evaporates, forms crystals, expand and put pressure on the rock, causing the rock to break
What is Chemical Weathering?
The breakdown of rock by changing it’s chemical composition
-mainly carbonation weathering
-seawater has CO2 dissolved in it, which makes them an acid
-carbonic acids react with calcium carbonate, so rocks are dissolved
What is Biological Weathering?
The breakdown of rock by living things eg. plant roots by growing into cracks and pushing it apart
What is Mass Movement?
The shifting of rock and loose material down a slope (cliff)
-happens due to the force of gravity being greater than the supporting force
When is Mass Movement more likely to happen?
When the cliff is saturated / lubricated with water - making the material heavier
3 types of Mass Movement?
Slides
Slumps
Rockfalls
3 types of coastal erosion + explanations
Hydraulic power - waves crash against rock and compress the air in the cracks, putting pressure on the rock. Repeated compressions widen the cracks
Abrasion - eroded particles in the water RUB against ROCK, removing small pieces
Attrition - eroded particles in the water SMASH into EACH OTHER and break into smaller fragments. Their edges become rounded off as they rub against each other
What type of Coastlines are there?
Concordant
Discordant
Describe Concordant coastlines
Alternating bands of soft and hard rock PARALLEL to the coastline
Erosional landforms like headlands are less common as the rock erodes at the same rate
Describe Discordant coastlines
Alternating bands of soft and hard rock perpendicular to the coast
Erosional landforms like headlands and bays are more common as the rock erodes at the same rate
How does the UK climate have an impact on Coastal Erosion?
-Temperature varies with seasons - coldest in winter, hottest in summer
-Storms are more frequent in the winter - strong winds create high energy, destructive waves which increase the rate of erosion on the cliffs
-Intense rainfall can cause cliffs to become more saturated - mass movement is more likely
Characteristics of Destructive waves
-High and steep (larger amplitude)
-High frequency (10-14 waves/minute)
-Backwash is more powerful than swash
-Increased rate of coastal retreat
What is a Wave-cut Platform? (How is it formed)
1) Waves cause erosion at the foot of a cliff, forming a wave-cut notch
2) The rock above becomes unstable and collapses
3) W-c Platform is the land that’s left behind after the cliff retreats
How do Caves, Arches, Stacks and Stumps form?
1) Waves crash into the cracks of the headlands and enlarge the cracks
2) Repeated enlargement causes a cave to form
3) Continued erosion deepens the cave until it breaks through the headland, forming an arch
4) Erosion continues to wear away the rock supporting the arch until it collapses
5) This forms a stack - isolated rock separated from the headland