Everything you need to know for The Coastal Zone

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Freez-thaw weathering (mechanical) 1)
Water gets into cracks in the rock and expands the crack when it freezes. When the water thaws it contracts and more water can enter the crack
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Freez-thaw weathering (mechanical) 2)
The continuing expansion and contraction of water puts stress on the rock as the crack widens, Eventually the rock breaks away
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Carbonation (chemical weathering)
Rainwater mixes with carbon dioxide to form a weak carbonic acid which dissolves rock containing calcium carbonate (chalk and limestone)
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Slides (mass movement)
Material shifts in a straight line down the cliff
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Slump (mass movement)
Material shifts with a rotation down the cliff
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Hydraulic power
The force of waves smashing water against rock and compressing air in cracks which puts pressure on the rock and causes erosion
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Abrasion
Eroded particles in the sea is scraped against the rock removing small pieces
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Attrition
Sediment is bumped against each other causing it to wear down and break apart
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Solution
Rocks like chalk and limestone become soluble with acid
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Destructive waves
Occur at times of storms. Erode the beach due to strong backwash and weak swash (steep beach gradient). Have a high frequency
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Constructive waves
Occur at times of calm weather. Build the beach due to weak backwash and strong swash..DEPOSITION (shallow beach gradient). Have a low frequency
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Wave cut platform 1)
Waves erode a WAVE CUT NOTCH at the foot of the cliff by hydraulic action and abrasion. The notch increases in size and the cliff above it becomes unstable and collapses
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Wave cut platform 2)
This process repeats until the cliff has retreated and a wave cut platform is left behind
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Headlands and bays
More resistant rock (e.g chalk) is not eroded and forms a headland. Less resistant rock (e.g clay) is eroded and forms a bay
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Cave to arch
Hydraulic action weakens a fault in a cliff and enlarge it, forming a cave. Eventually the cave becomes an arch due to erosion
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Arch to stack
The top of the arch becomes weak and collapses into the sea, leaving a stack
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Stack to stump
Further erosion may cause the stack to topple over, leaving a stump
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Longshore drift 1)
The transport of material along a coastline: prevailing wind directs the waves towards the coast at an angle
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Longshore drift 2)
The swash carries sediment up the beach and the backwash carries it back down at a right angle. The sediment zigzags across the coast
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Traction
Boulders pushed/rolled along seabed by force of water
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Saltation
Pebbles bounced along the seabed
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Suspension
Tiny particles carried with the sea
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Solution
Dissolved materials transported by sea
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Beaches
Formed by constructive waves depositing material
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Shingle/ pebble beach
Steep and narrow. Too heavy to be moved back down the beach
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Sand beach
Wide and flat. Creating a long gentle slope/ gradient
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Spits
Beaches extending past sharp bends in the coastline due to longshore drift
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Bar
When a spit crosses a bay/joins two headlands together. A lagoon forms behind it
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Rising sea level
Rising at 2mm per year because of global warming heating oceans and melting ice
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Heating of oceans
When water heats up it expands (thermal expansion) - the volume increases
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Melting ice
The melting of ice caps and sheets in polar regions, due to the increase of global temperature, adds a greater volume of water to the oceans
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Economic effects of sea level rise
Loss of tourism. Damage repair. Loss of agricultural land
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Environmental effects of sea level rise
Vegetation and animals killed by salt water. Increased erosion
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Social effects of sea level rise
People lose houses. Unemployment. Damage of water supplies. Deaths
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Political effects of sea level rise
Government have introduce policies to reduce the impacts by building defences or managing areas to be used for flooding
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Economic effects of sea level rise in East Anglia
Industry lost (especially in London). Norfolk broods flooded - no tourism. Defences to reduce impacts
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Social effects of sea level rise in East Anglia
Communities destroyed e.g Kings Lynn. Farmland destroyed. Fear of storm surge that hit the east coast (killing 300) happening again
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Political effects of sea level rise in East Anglia
Government deciding whether to protect some areas and let others flood. Do they protect Kings Lynn?
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Environmental effects of sea level rise in East Anglia
Weaken sea defences so more erosion. 20% of saltmarshes lost by 2050. Habitats and biodiversity destroyed
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Holderness erosion case study
Coastline is 61km long. 1.8m lost every year.. 10m in Great Cowden.
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Holderness erosion causes
Weak rock type (clay). Narrow beaches. Groynes in place updrift causing deprivation of sediment. Directly facing the prevailing wind with long fetch, so powerful waves
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Social impacts 1)
Homes near cliffs at risk of collapsing. Property prices fallen. Roads to some settlements closed. Businesses at risk e.g Seaside Caravan park so threat of unemployment.
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Social impacts 2)
Gas terminal accounting for 25% of Britain's supply is 25m from edge. 80,000m2 of farmland lost per year
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Environmental impacts
some SSSI's (Sites of Scientific Special Interest) such as the Lagoons near Easington are in danger
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Groynes (hard engineering)
£10,000 each. Wooden structures built at right angles to the beach which stop longshore drift by trapping the material - to prevent erosion of coastline
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Advantages of groynes
They are relatively cheap. Wider beaches means less erosion and more tourism
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Disadvantages of groynes
They are unattractive. They starve areas of beach downdrift of them which leads to erosion elsewhere
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Sea walls (hard engineering)
£6mil per km. Reflect the power of the wave back into the sea to try to stop erosion
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Advantages of sea walls
Effective at preventing erosion and flooding. Can be used as a promenade
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Disadvantages of sea walls
Are unnatural and obtrusive. Are very expensive to build and maintain. Create a strong backwash which erodes under it
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Rock armour
£1,000-£4,000 per m. Boulders piled up along the coast which absorb the force of the wave
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Advantages of rock armour
Relatively cheap. Tourist interest. Easy to maintain and put together
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Disadvantages of rock armour
Obtrusive and unnatural. Transport from other countries is expensive
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Beach nourishment (soft engineering)
£3000 per m. Collecting sediment from the seabed and adding it to the beach to give more protection against erosion
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Advantages of beach nourishment
Natural and unobtrusive. Creates bigger beaches so more tourism. Cheap and easy to maintain
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Disadvantages of beach nourishment
Has to be maintained often.
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Dune regeneration (soft engineering)
£2000 per 100m. Adding plants and extra sediment to sand dunes
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Advantages of dune regeneration
Cheap. Natural for people and wildlife
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Disadvantages of dune regeneration
Takes time to work as plants need to grow. Damaged by storms
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Managed retreat
Allowing some areas of the coast to be eroded to reduce the intensity of erosion elsewhere
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Advantages of managed retreat
Cost effective - compared to other maintenance schemes. Creates habitat for wildlife
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Disadvantages of managed retreat
Agricultural areas/ farmland destroyed and owners need to be compensated
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Bridlington, Holderness
4.7km sea wall and groynes
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Hornsea, Holderness
Sea wall, groynes, rock armour
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Withersea, Holderness
Groynes and sea wall. Rock armour placed in front of wall after storm in 1992
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Mappleton, Holderness
£2mil rock groynes
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Less erosion at Holderness
The Humber estuary is more likely to flood as it is carrying less material. More erosion along the Lincolnshire coast. Bays forming between protected areas so they become headlands. Spurn head spit at risk.
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Keyhaven salt marsh
Formed behind Hurst Castle spit. Retreating by 6m a year
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Keyhaven salt marsh wildlife
Cordgrass. Sea lavender. Oystercatcher bird. Butterflies. Wold spider
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Threats to Keyhaven salt marsh
In 1989 a storm exposed 80m to the sea which was eroded in 3 months. Increasing demands for leisure and tourism (trampling, parking, pollution). Rising sea levels
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Responses to threats to keyhaven salt marsh
1996, £5mil spent on rock armour and beach nourishment to protect the spit. Is a SSSI and a nature reserve so is carefully monitored
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Other cards in this set

Card 2

Front

The continuing expansion and contraction of water puts stress on the rock as the crack widens, Eventually the rock breaks away

Back

Freez-thaw weathering (mechanical) 2)

Card 3

Front

Rainwater mixes with carbon dioxide to form a weak carbonic acid which dissolves rock containing calcium carbonate (chalk and limestone)

Back

Preview of the back of card 3

Card 4

Front

Material shifts in a straight line down the cliff

Back

Preview of the back of card 4

Card 5

Front

Material shifts with a rotation down the cliff

Back

Preview of the back of card 5
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