Flashcards in Coasts Deck (83):
What is the rate of erosion in the holderness coast?
1-2 meters every year.
100 s of rocks are eroded every tide.
Mappulton was 4km away from the sea 200 years ago.
6 houses have gone in the last 15 years.
How is Bridlington being protected in the Holderness coast?
There is a 4.7 km sea wall as well as groynes that stop material being moved.
How is Hornsea being protected in the Holderness coast?
There is a sea wall, wooden groynes and rock armour. This is because it is a popular tourist resort so money would be lost if it wasn't protected.
How is Mapperlton being protected in the Holderness coast?
In 1991 half the towns budget was spent on two million pound rock groyne. This collects material which stops erosion. Only 100 people live there and the houses aren't worth saving but the B1242 road goes through it. It would cost millions to re-route it so it is being protected.
What are the consequences of the rock groyne at Mappulton?
It means no material can get further down the coast to replenish the eroded material. The farm land there is being eroded and people have to be moved. The land isn't worth much so it is left.
At Great Cowden that rate of erosion is 10m per year.
How is Withernsea being protected in the Holderness coast?
Groynes have been put in place to create a wider beach. There is also a sea wall and rock armour in front of it.
How is Easington being protected in the Holderness coast?
A sea wall was put up. This is because there is a gas refinery which produces 20% of the UK's gas there.
How is Spurn Head being protected in the Holderness coast?
The eastern side has groynes and rock armour. This is because groynes put up along the coast prevent LSD from moving material to the spit.
Why is there such a large rate of erosion in Holderness?
The cliffs are made of boulder clay which is likely to slump when wet, causing cliff collapse.
The beaches are narrow meaning they can't absorb the power of the waves.
Holderness faces the prevailing wind. Waves from the north west( all the way from the arctic ocean) there is a long fetch meaning the waves are very powerful.
Groynes are capturing material meaning it can't be replenished when eroded.
What is the effect of such high erosion at the Holderness coast?
80,000 square meters of farm land is lost each year meaning farmers lose money.
Businesses are at risk. The seaside Caravan Park loses 10 pitches a year.
Property prices have fallen and it is hard to insure them.
Some SSSIs are threatened. Lagoons near Easington are being protected by a bar. If this is eroded the lagoons will be destroyed.
What and where are the Maldives?
There are a collection of 1190 islands south of India in the Indian Ocean. 300,000 people live there.
80% of the islands are less than 1m below sea level. Sea levels go up by 9mm a year and experts say they will be gone between 50-100 years.
What are the economic effects of coast flooding in the Maldives?
Tourism is the largest industry in the area. If the airport can't function because of flooding international tourists won't be able to come which will massively reduce the income.
Fish is the islands largest export. Coastal flooding may damage fish processing plants, reducing the fish exports and the country's income.
What are the social effects of coast flooding in the Maldives?
Houses are damaged or destroyed. A flood could make entire communities homeless. People would have to be re housed and public buildings rebuilt.
Less fresh water available. Supplies are already low and a flood would contaminate water. Some islands would depend on rain water or have to buy expensive desalination plants.
What are the environmental effects of coast flooding in the Maldives?
Coastal flooding means beaches are worn away and habitats are destroyed or left exposed if it's the land behind beaches.
The soil layer is about 20cm. A flood could wash the soil away meaning nothing will grow.
What are the political effects of coast flooding in the Maldives?
The Maldivian Government asked the Japanese Government for $60 million to build a 3m high sea wall around the capital of Malé.
The Maldives has pledged to become carbon neutral so stop the effects of global warming. It want's other nations to do the same.
The government is thinking about buying land in India and Australia and moving people there before the islands become uninhabitable.
What is mechanical weathering?
The breakdown of rock without changing its chemical composition.
Explain freeze thaw weathering.
It occurs when the temperature alternates above and below 0 degrees.
Water gets into cracks in a rock.
When it freezes it expands putting pressure on the rock.
When it thaws it contracts, the pressure is released.
Repeating the process means the rock breaks up.
What is chemical weathering and give an example.
The breakdown of rock by changing its chemical composition. Carbonation weathering happens in warm and wet climates.
Rainwater with co2 in it becomes a weak carbonic acid. This reacts with calcium carbonate so the rocks are destroyed.
What is mass movement?
This shifting or rocks and loose material down a slope. It happens when the force of gravity is greater than that of the force supporting it.
It causes coastlines to retreat rapidly.
Is is more likely to happen when the land is full of water as it weighs the cliff down and acts asa lubricant.
What is slide?
Mass movement when material shifts in a straight line.
What is a slump?
Mass movement when material shifts with a rotation.
What are the four types of erosion?
Hydraulic, abrasion, attrition,solution.
Explain hydraulic power.
Waves crash against rock and compress air in the cracks creating pressure. Repeated pressure widens the cracks causing erosion.
When the sea hurls stones at a cliff face, causing bits to break off.
Eroded particles in the water smash together and break into smaller fragments.
Weak carbonic acid in seawater dissolves chalk and limestone.
Explain destructive waves.
They carry out the erosion all processes.
High have a high frequency. (10-14 waves a minute)
High and steep.
The backwash is more powerful than the swash meaning they move material down the beach.
More common in winter.
How are wave cut platforms formed?
Waves eroded the foot of a cliff the most.
This form wave cut notches which is enlarged as wearing and erosion continues.
The rock above the notch will become unstable and collapse.
This collapsed material is washed away and a new wave cut platform will start to form.
Repeated collapsing results in the cliff retreating.
A wave cut platform is what's left when the cliff has retreated.
How do headlands and bays form?
Along a coast there will be alternating bands of hard and soft rock. Some will be resistant to erosion, some won't.
The soft rock is eroded quickly and this forms a bay which will have a gently slope.
The hard rock is eroded more slowly and is left jutting out forming a headland with steep sides.
How do caves, arches and stacks form in headlands?
Headlands are made of strong rock but it still has weaknesses in the form of cracks.
Waves crash into headland and enlarge the cracks, mainly be hydraulic power and abrasion.
When this is repeated the cracks will get bigger and form a cave.
Repeated erosion will deepen the cave until it breaks through the headland forming an arch.
Erosion continues to wear away the rock that's supports the arch until it collapses.
This forms a stack which is an isolated rock that is separate from the headland.
What is Long shore drift?
It transports material along the coast.
Waves will follow the direction of the prevailing wind.
This means they usually hit the coast at an angle.
The swash will carry material in the same direction as the waves.
The backwash will then carry the material back down again at right angles back towards the sea.
Overtime material will be zigzagged along the coast.
When drawing a diagram of LSD what must you remember to have?
Arrow for direction of prevailing wind.
Arrow for direction of material movement.
Arrow for swash and backwash.
Key for the arrows.
What is deposition and when does it happen?
It is when material being transported by the sea is dropped along the coast.
Coasts ate built up when the rate of deposition is greater than the rate of erosion.
The amount of deposition is increased when
There's lots of erosion elsewhere along the coast giving material
There's lots of transportation of material into the area.
Low energy waves cause the most deposition as they aren't strong enough to take material away.
Explain constructive waves.
They have a low frequency.(6-8 waves per minute)
They're low and long.
The swash is powerful, carrying material up the coast.
The backwash is weaker and doesn't move a lot of material down the coast.
More common in summer.
How are beaches formed?
Beaches are found between the high water mark and the low water mark.
They form by constructive waves depositing material.
What are the characteristics of sand beaches?
They are flat and wide. Sand particles are small and weak, meaning the backwash can move them back down the beach creating a long gentle slope.
What are the characteristics of shingle beaches?
They are steep and narrow. As shingle particles are large the weak backwash can't move them down the beach. They build up and create a steep slope.
What are spits?
They are beaches that stick out into sea joined to the land at one end.
Where and how do spits form?
They form at sharp bends in the coastline e.g. a river mouth.
Longshore drift transports sand and shingle past the bend and deposits it on the sea.
Strong winds can curve the end(called a recurved end)
The sheltered area behind the spit is protected from the waves. Lots of material accumulates in the area meaning plant life can form.
Over time, the sheltered area can become a mud flat or salt marsh.
What is a bar?
It is when a spit connects two areas of land together.
Where do bars form?
At two headlands, it joins them together.
The bar cuts off the bay between the headland and the sea. This means a largo on can form behind.
How are caves, arches and stacks found on a map?
Caves and arches can't be seen but stacks look like little blobs in the sea.
How are cliffs and wave cut platforms shown on a map?
Cliffs are shown as little black lines along the coast.
Wave cut platforms are shown as bumpy edges along the coast.
How are beaches shown on a map?
They are yellow areas. Single beaches have spots.
What are the two ways in which global warming causes sea levels to rise?
Ice melts meaning there is more water and the water gets hotter meaning or expands and takes up more space.
What are the economic impacts of coastal flooding?
Loss of tourism as coastal tourist destinations are lost.
Money is spent repairing the expansive damage caused by flooding.
Loss of agricultural land. The salt in the sea will reduce soil fertility so crop production will be reduced for years after a flood.
What are the social impacts of coastal flooding?
Deaths. They have killed thousands in the past.
Water supplies are polluted by sea water or sewage.
Loss of housing.
Loss of jobs. Coastal industries like fishing can be destroyed because of damage to equipment and buildings.
What are the environmental impacts of coastal flooding?
Ecosystems affected. The sea salt can damage or kill organisms in an ecosystem
Vegetation killed. Standing flood water drowns trees and plants while the force of water can up root plants.
Increased erosion. A large volume of fast moving water can erode material and damage the enviroment.
What are the political impacts of coastal flooding?
The government has to make polices to reduce the impacts of flooding. They can manage areas that are prone to flooding or build large flood defences.
What is hard enginering?
Man made structures built to control the flow of of the sea and reduce flooding and erosion.
What is soft enginering?
Schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion.
What is a sea wall?
A wall made out of hard material that reflects waves back out to sea.
What is rock armour?
Boulders that are piled along the coast.
What are groynes?
Wooden or stone fences built at right angles to he coast. They trap material moved by longhorn drift.
What is beach nourishment?
Sand and shingle from elsewhere is added to the beach.
What is sand dune regeneration?
Creating or restoring sand dunes by either adding more material or planting vegetation to stabilise the sand.
What is marsh creation?
Planting vegetation in mudflats along the coast.
What is a managed retreat?
Removing an existing defence and allowing the land behind it to flood.
What are the benefits of sea walls?
It prevents erosion of the coast. It also prevents flooding.
What are the benefits of rock armour?
The boulders absorb wave energy and reduce erosion and flooding. It's a fairly cheap defence.
What are the benefits of groynes?
They create a wider beach which absorbed wave power. This gives greater protection from flooding and erosion. They're fairly cheap.
What are the benefits of beach nourishment?
It creates wider beaches which absorb wave power, protectin from flooding and erosion.
What are the benefits of sand dune regeneration?
Sand dunes provide a barrier between the land and sea. wave energy is absorbed which prevents flooding and erosion.
What are the benefits of marsh creation?
The vegetation stabilises the mud flats which reinsured the spread of waves. This prevents flooding and erosion. It also created new habituates for organisms.
What are the benefits of a managed retreat ?
The land will become a marsh land and a new habitat will be created. Flooding and erosion will be reduced. It's a fairly cheap defence.
What are the disadvantages of sea walls?
It creates a throng backwash which erodes under the wall. This means they are expensive to build and maintain. Ugly.
What are the disadvantages of rock armour?
Boulders can be moved around by strong waves so they have to be replaced. Ugly
What are the disadvantages of groynes?
They starve the beaches further down of material, meaning they become narrower. These don't protected against erosion as well.
What are the disadvantages of beach nourishment?
Taking material from the seabed can kill organisms like sponges and corals. It's a very expensive defence as it has to be repeated.
What are the disadvantages of sans dune regeneration?
The protection is limited to a small area.
What are the disadvantages of marsh creation?
Where the erosion rates are high is can't be used as the marsh can't establish them selves. It is also very expensive.
What are the disadvantages of a managed retreat?
People may disagree on what land is let to be eroded. It could affect the livelihood of animals.
Where is are the Keyhaven marshes?
Formed on the lee of hurst cast spit. In the south east.
What are the characterises of the Keyhaven marshes?
It is an area of grasslands, scrubs, salt marshes and reed beds.
Give some examples of how vegetation and how it has adapted in the Keyhaven marshes.
Cordgrass is salt tolerant and quickly colonies mudflats.
It has long roots so it isn't swept away with the tides and the roots help trap sediment and stabilise the soil. This is a pioneer plant. There ate many other types of grass, scrubs and reed beds.
What threatens the Keyhaven marshes?
It is retreating at a rate of 6mm a year. No one ones why.
Rising sea levels squeeze salt marshes between a sea wall and the sea. Tourism means the area is at risk of trampling, being parked on and polluted. Mariners use the creek to moor their boats.
The hurst caste spit an be eroded by the sea. In 1989 50-80m was exposed to the sea and it was erode in 3 months.
What are he solutions to the problems at the Keyhaven marshes?
In 1996 £5m was spent on rock armour and beach nourishment to increase the height and width of the spit to prevent breaching.
It is a SSSI, meaning the area is carefully monitored and managed to insure a rich biodiversity. It is a important site for wild fowl and wading birds.
Explain onion skin weathering.
Also know as exfoliation.
The rock is heated during the day by the sun and expands.
In the night it cools and contracts. Continued contraction and expansion causes weathing.
What is biological weathering?
It can be caused by plants and animals.
A plants roots can get into a crack. As the plant grows bigger so does its roots and the crack is forced open.
Moles, golfers and burrowers go into the ground.
How does a cove form?
An area of soft rock is surrounded by hard rock, with an thin area of hard rock facing the sea.
This will get eroded and the waves will have access to the soft rock which will be quickly eroded. Hard rock will remain for a longer time.
What are the advantages of beach management?
Tourism can be improved.
Property, businesses and transport links can be saved.
What are the disadvantages of beach management?
The effect on erosion further down the coast. Unattractive, cost of upkeep. Political-court cases.