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.
What is mechanic weathering?
When weathering breaks larger masses of rocks into smaller ones. E.g. freeze-thaw - when water gets trapped in cracks, it freezes and the cracks expand. It happens most often when temperatures regularly fluctuate above and below 0ºC.
What is mass movement?
The downhill movement of materials under the influence of gravity.
What do different types of mass movement depend on?
- the material involved
- the amount of water in the material
- the nature of the movement e.g. falls, slips or rotational slides
How does sliding occur?
When loosened rocks and soil suddenly tumble down the slope. Blocks of material might all slide together
How do slumps occur?
When the rock (often clay) is saturated with water and slides down a curved slip plane
What does coastal erosion lead to?
Coastal retreat
What is coastal retreat?
When the coast moves further inland
What three types of coast will erode quicker?
- Coasts exposed to frequent storms
- Soft rock coastlines
- Cliffs with many faults and joints
What are the five steps of longshore drift?
- Waves approach the coast at an angle
- Swash pushes sand and gravel up the beach at the same angle
- Backwash carries sand and gravel back down the beach at 90º to the coastline under gravity
- Sand and gravel travel along the beach in a zigzag fashion
- Sand is lighter than gravel and so travels further up the beach
What are the 4 types of wave transportation?
- Traction
- Saltation
- Suspension
- Solution
What is traction?
When large boulders are rolled along the seabed by waves
What is saltation?
When smaller stones are bounced along the seabed
What is suspension?
When sand and small particles are carried along in the flow
What is solution?
When some minerals are dissolved in seawater and carried along in the flow
What factors influence and reduce wave energy deposition?
- sheltered spots (e.g. bays)
- calm conditions
- gentle gradient offshore causing friction
How are beaches formed?
By waves refracting or bending as they enter a bay
What causes shingle beaches?
Where cliffs are eroded by often powerful waves
What are berms?
Ridges in the beach parallel to the sea
What are spits?
Long narrow projections of sand or shingle that are attached to the land at one end.
How and where are Spits formed?
By longshore drift powered by strong prevailing winds - they extend across a bay, estuary or where the coastline changes direction.
What are bars?
A form of spit that reaches right across a bay cutting it off and forming a lagoon
How does development negatively affect the coast?
- The weight of buildings increase cliff vulnerability
- changes in drainage increase saturation
How does development positively affect the coast?
raises interest in protecting coastal landscapes
How does industry negatively affect the coast?
- can cause/increase air, soil, water and noise pollution
- can destroy natural habitats for birds, animals and sea life
How does industry positively affect the coast?
brings wealth and jobs to rural coastal regions
How does agriculture negatively affect the coast?
- Increased soil erosion
- Increased sedimentation
How does agriculture positively affect the coast?
wildlife habitats may be created and preserved
How does coastal management negatively affect coasts?
Can increase erosion further along the coastline
How does coastal management positively affect coasts?
- Helps reduce the risk of coastal flooding
- Some salt marshes, dunes, sand bars and spits are preserved and protected
How does tourism positively affect the coast?
- increased revenue benefits for people living there
- Increased desire to protect and preserve landscape so tourism continues
How does tourism negatively affect the coast?
- Increased development for campsites has impacts on natural processes, e.g. deportation and mass movement
- Increased pollution, e.g. littering, noise and traffic fumes
What two ways does climate change increase coastal erosion?
- As atmospheric temperatures rise, storm frequency and strength increase
- As sea temperatures rise, coastal flooding will become more frequent and severe
On the Holderness coast, What physical processes caused changes to the coastline?
- cliffs eroded at 1.5 million tonnes a year
- 2 million tonnes of material is eroded via hydraulic action, abrasion and attrition
Describe H:
East Yorkshire and is one of the most vulnerable coastlines
The significance of H:
- Rock type is soft boulder clay, which is easily eroded and prone to slumping when saturated.
- Exposed to strong waves from the north sea
- Harder chalk rocks at Flamborough Head
Physical processes at H:
- mass movement - clay slumps
- Transportation - strong waves move the eroded material away from the coastline
Human processes at H:
- Hard engineering has been used such as rock armour and groynes at Mappleton which has protected the coast from some erosion
- Groynes in some places have prevented transportation, making erosion worse in other places
What are two examples of hard engineering?
- sea wall
- Groynes
Give one advantage of using a sea wall and one disadvantage:
- it protects cliffs and buildings
- Expensive
Explain one advantage and one disadvantage to using groynes:
- prevents the sea from removing sand
- exposes other areas of coastline
Give two examples of soft engineering:
- beach replenishment
- slope stabilization
Give one advantage and one disadvantage to using beach replenishment:
- sound reduces wave energy and maintains tourism
- expensive
Give one advantage and one disadvantage of using slope stabilisation:
- reduces slippage
- foot of cliff still needs protection from the waves
What are the three methods of integrated coastal zone management?
- do nothing
- hold the line
- strategic realignment
What are the benefits and the costs of doing nothing?
- cheaper than taking action
- homes and land lost
What are the benefits and costs to holding the line?
- existing shoreline maintained
- expensive
What are the benefits and costs of Strategic realignment?
- people and activities move in Land
- unpopular with local residents
