Coastal change and conflict Flashcards
Give 2 characteristics of soft rock landscapes:
- Bays
- Less rugged and less steep cliffs
Give 3 characteristics of hard rock landscapes:
- High, steep and rugged cliffs
- Wave-cut platforms
- headlands with caves, arches and stacks
What is the difference between faults and joints?
Joints are small cracks in rock and Faults are large cracks in the rock
What do faults and joints do to rocks?
Make them more susceptible to erosion
What are concordant coasts?
Coast made of one rock type
What are discordant coasts?
Coasts made of numerous types of rock
What 4 factors affect rates of erosion?
- Geological structure - type of rock
- Wave Climate - power, direction, height and fetch
- local currents and tidal range - difference in low and high tide
- groundwater levels - saturated cliffs (high groundwater) more vulnerable
What is fetch?
How far winds travel over open water
What is ‘differential rates of erosion’ a term for?
When rocks of differing resistance are eroded at different rates
How is a cave formed?
When a joint or fault in the rock is eroded by waves
How is an arch formed?
When two caves erode back from either side of a headland and meet in the middle
How is a stack formed?
When an arch collapses
How is a stump formed?
When a stack is eroded by wind and water
What is a wave-cut platform?
an area of flat rock at the base of a cliff
How are wave-cut platforms formed?
- waves undercut and erode the cliff under the sea level.
- Thus an overhang is produced
- the overhang collapses
- hence the cliff retreats inland
- Left behind is the wave-cut platform
What are the 5 main ways waves erode?
- destructive waves
- hydraulic action
- abrasion
- attrition
- solution
What is hydraulic erosion?
Where the sheer weight and power of waves erodes rock. Waves also compress air in cracks causing them to split further.
What is abrasion?
When breaking waves throw sand, boulders and rock at the coast.
What is attrition?
When the rocks and pebbles carried by waves rub together and break down into smaller pieces
What is solution erosion?
When chemical action by seawater on some rocks especially limestone, erodes it
What is a destructive wave?
When backwash is strong and drags material on a beach back down into the sea
What 3 things cause coastal erosion that is related to the British climate?
- Seasons and weather change
- Prevailing winds (southwesterly)
- Storm frequency
How do different seasons affect coastal erosion?
Cold temperature leads to freeze-thaw weathering in cliffs
How do prevailing winds affect coastal erosion?
It brings warm, moist air from the Atlantic ocean which causes high rainfall, hence weathering and mass movement
How does high storm frequency effect
coastal erosion?
It brings strong rainfall and strong winds which cause more powerful waves
What is the UK’s climate?
Temperate maritime - mild, wet winters and warm, wet summers.
What are the 3 main types of weathering?
- Biological
- chemical
- Mechanical
What is Biological weathering?
Caused by plants and animals - plants grow in cracks and roots cause the widening of them
What is chemical weathering?
- When rocks composition is changed
- E.g. Granite contains feldspar which converts to soft clay when in contact with water
- Limestone is dissolved by carbonation.
What is carbonation?
When Carbon dioxide in the atmosphere mixes with rainwater to form carbonic acid. This then reacts with Calcium Carbonate (Limestone) and turns it into calcium bicarbonate. This is carried away by water in solution.