Coasts Flashcards
What determines the waves energy?
The length of fetch, the strength of the wind, and the length of time over which the wind has blown.
What is a Coast line?
A coastline is where the sea and the land meet. They constantly change due to the action of the sea weather and humans.
Definition of ‘a constructive wave’
A wave that has a greater swash than backwash
Definition of ‘length of fetch’
The distance over which the wind has blown across the surface of the sea
Definition of ‘swash’
The transfer of a waves energy up the beach
Definition of ‘destructive wave’
A wave that has a greater backwash than swash.
Definition of ‘backwash’
Transfer of a waves energy down the beach
Definition of ‘wave’
The movement of the wind across the surface of the sea.
How are waves formed?
Waves are a result of the wind blowing over the sea. As they approach land the break. The bottom of the wave touches the sand and slows down due to increased friction. The top of the wave becomes higher and steeper until it topples over.
Name the two dominant processes of coastal erosion
Hydraulic action
Abrasion
Definition of ‘hydraulic action’
This process involves the force of water against the coast. The waves enter faults in the coastline and compress the air within the crack. When the wave retreats the air in the crack expands quickly causing a minor explosion. This process is repeated continuously.
Definition of ‘abrasion’
This is the process by which the coast is worn down by materials carried by the waves. Waves throw this sediment against the rock, sometimes at high velocity.
What are the 4 processes of transportation?
Traction - this is when large boulders are rolled along the sea bed.
Saltation - this is when smaller boulders are bounced along.
Suspension- this is when sand grains are carried along.
Solution - when a material dissolves into the sea to form a solution.
What are sub-aerial processes?
Weathering and mass movement.
Definition of ‘mass movement’
This is when rain water seeps through the land and saturates it. It can no longer hold its shape due to gravity and landslides occur. Holbeck hall in Scarborough is an example of this. This especially happens in areas of softer rock such as Boulder clay.
Definition of ‘ freeze thaw weathering’
Water finds its way into cracks in the rock. It then freezes and expands by 8-10% over night. This process is repeated over and over again putting pressure on the cracks in the rock. This is a slow process that can take many years.
Definition of ‘biological weathering’
Plant roots get into tiny cracks in rocks. As the roots push their way upwards to the surface of the rock, they force open the cracks further. This causes small pieces of the rock to break away. The roots can rot and leach out acids that can further weather the rock.
Definition of ‘chemical weathering’
Chemical weather is the dissolving of rocks caused by acid rain. Rainfall is slightly acidic due to the presence of carbon dioxide in our atmosphere. As it falls the the ground it reacts with the metal carbonates with rocks and slowly dissolves them. This causes a weak carbonic acid. Limestone is particularly prone to this type of weathering as it is an alkaline rock.
What coastal features are created by erosion?
Headlands and bays
Wave cut platforms
Caves, arches, stacks, and stumps
How are Headland and Bays created?
Waves erode the softer rock more quickly than the hard rock via abrasion. This is when the sea throws sediment against the coastline. A bay is formed in the softer rock such as clay. Beaches are formed in the bay’s due to constructive waves found there. An example is Selwick Bay at Flamborough Head in East Yorkshire.
How are wave cut platforms created?
Destructive waves hurl sediment at the base of the cliff undercutting it - this is abrasion. A wave cut notch is formed, making the cliff unstable. The wave cut notch grows and eventually the cliff collapses due to gravity. The backwash carries the rubble towards the sea forming a wave-cut platform. The process repeats and the cliff continues to retreat.
How is a stump formed?
Lines of weakness such as faults occur ing the headland.
Abrasion and hydraulic action erode the fault to from a cave.
The cave is widened an depend.
The sea cuts through the cave to form an arch.
The roof of the arch becomes too heavy and collapses.
Part of the former cliff is now isolated as a stack.
Over time the stack is undercut and collapses.
A stump is the remains of the eroded stack.
An example of this is in Selwick Bay at Flamborough in East Yorkshire.
Why is the Holderness coastline European fastest eroding coastline?
Because it is made out of Boulder clay which was deposited after the ice age.
Definition of ‘long shore drift (LSD)’
Longshore drift involves the zigzag movement of eroded material along a coastline. Waves approach a coast at a 45* angle and erode away part of the coastline. However the backwash transports material away from it at a 90* angle. The next waves then transports this material along the coast. Material is deposited when the seas energy is slowed down for example at a river entering the sea. It then deposited the material building a spit.
How are beaches formed?
The beach is the gently sloping area between the high and low tide. Beaches constantly change as sand, pebbles, and shingle keep being moved on and replaced by new material. Material forming a beach are carried by LSD. When the coastline becomes more sheltered, for example in a bay, constructive waves are more likely to occur. These waves have a greater swash which means that material accumulates over time and builds up a beach.
Give an example of a spit.
Spurn Head
How is a spit formed?
Spots are created by LSD. When the sea is slowed down, for example where it meets a river, deposition takes place. This extends out from the land. Fresh water and sea water are trapped behind the spit and marshes grow here. As the spit extends into deeper water, the end of the spit is affected by strong winds and it may curve.
What is a bar?
If a spit joins one part of the mainland to another it is called a bar.
What is a tombolo?
A spit connecting an island to the mainland e.g chesil beach, Dorset.
Definition of ‘hard engineering’
Man made
Definition of ‘soft engineering’
Natural
Name 6 hard engineering coastal defence methods
Sea wall Groynes Rock armour Offshore breakwater Revetments Gambions
Name 2 soft engineering coastal defence methods
Managed retreat
Beach replenishment
What is managed retreat?
It involves allowing the land to be flooded. This land is then left to be colonised by a salt marsh. When it has grown in height, it slows down wave energy, reduces erosion, and provides new habitats for animals
How does rock armour work?
When the wave hits the boulders they absorb some of the waves energy by slightly moving. This stops the cliff getting the full impact of the wave.
How do groynes work?
They trap sediment that was being transported down the beach by longshore drift. This builds up a beach which is a natural sea defence
Where is Mappleton located?
Mappleton is located on the east coast of the uk on the Holderness coastline in East Yorkshire.
Name the road that goes from hull to Hornsea
B1242
What sea defences do they have at Mappleton?
Two rock groynes
Rock armour
What are the physical features of the Holderness coastline
It is made out of boulder clay which is a very soft rock so the rate of erosion is quick.
Where is Hornsea located?
Hornsea is located on the east coast of the uk on the Holderness coastline North of Mappleton.
What are the positives and negatives of the sea defences at Mappleton?
Positives:
Protects the town
Protects the b1242
Negatives:
Erosion has sped up 5x from 2m per year - 10m per year
People losing their homes further down the coast
Cost a lot of money to buy
What sea defences are at Hornsea?
Wooden groynes
Rock armour
Sea wall
What are the economic, benifits of protecting Hornsea
The benefits of protecting Hornsea are economic because 70% of Hornsea’s local economy is dependant on tourism.
What is the name of the caravan park in Hornsea
Promenade caravan Park
Give an example of managed retreat
Abbots Hall Farm, Essex
Why are sand dunes a good sea defence
They are natural an look nice
Why and how do they strengthen sand dunes?
They can be easily broken up during heavy storms and can be completely washed away. You strengthen them by making them bugger and putting a mat in front. This also traps and wind blown sand which helps make it bigger.
What are rhizomes?
Roots that reach down into sand dunes to get to the fresh water deep below the surface. They are important because the roots strengthen the dune. Also the leaves trap the wind blown sand building up the dune, making it stronger. An example of a rhizome is marram grass.
Where is Spurn Head?
Spurn head is located on the Holderness Coastline in the east of the UK.
What type of land form in Spurn Head?
Spit
Where are the sand dunes located on Spurn Head?
On the eastern side.
What process creates sand dunes?
Saltation
Where are the mud flats on spurn head
West side
How are mud flats created?
Water is slowed down and deposits the material its carrying
What plants are found on Spurn Head?
Marram grass
Spiky cord grass
They can survive here because they can live in dry conditions and can survive in salt water.
What birds are found on spurn head?
Oystercatchers
Geese
Plovers
What is the food chain on spurn head?
Dead plants -> tiny animals -> cockles and lugworms -> crabs and fish -> seals and birds
What are the conflicts on the spit?
Tourists annoy farmers and twitchers a they disturb birds and livestock as well as trespassing.
Twitchers and farmers annoy tourists because they put keep out signs up so they can’t see the local wildlife.
Nature annoys farmers because the land is getting washed away.
Lifeboats annoy nature and twitchers because the noise from them disturbs birds.
What is being done to conserve spurn head?
The ‘Sea Bird Observatory’ is being built with eating/toilet facilities and information displays about the life on this spit.
‘Humber Estuary Shoreline Managment Plan’ rebuilding groynes to trap sediment and help protect the spit from the sea. This will also help keep shipping lanes open.
‘Controlled tourism’ during the migration and nesting season. Visitor numbers are controlled to cut down noise.
Where are the Maldives
The Maldives are located in the north of the Indian Ocean. It is South west off the coast of India.
Why does the Maldives attract tourists.
The Maldives attract tourists from all over the world. It is a luxury destination where you can snorkel and scuba dive in the coral reefs, swim in the turquoise sea, relax on the paradise white beaches, and go on nature trails around the island.
What is the capital of the Maldives?
Malé
What are the main industries in The Maldives?
Tourism and tuna fishing
How many Maldivian islands are there?
1191
How many islands will disappear if the seas rise by 2 inches
953
Who do the locals on the Maldives blame for sea level rise?
The UK America China and India because of the emissions they produce and all the cars they have.
What are the two changes that are happening to the sea around the Maldives
Coral reefs are dieing
Sea level rise due to global warming and destructive waves erode the coastline.
What makes a natural barrier around the Maldives
Coral reefs because they slow the waves down
How is the coral being harmed
Tourists touching it
Tourists boats dropping anchors
Sea temps rising causes it to bleach and die
Used it to build houses
What is being done to protect Malé?
As a temporary protects sand bags were used. They have now constructed what the call ‘the big wall’ a cement wall 1.5m hight, 5km long and at the cost of $40 million.
What forms of protection are being used in the Maldives?
'The big wall' Using rubbish (not glass and plastic) and putting sand on top to compact it together and make a barrier. Low tech offshore breakwater
How may Maldivian island are inhabited?
200
What are the two main industries in the Maldives?
Tourism and tuna fishing
Why have the Maldives government decided to build an artificial island?
To provide space to accommodate people so people have somewhere to go if their island becomes uninhabitable. They can’t move to malé as it is overpopulated.
What is the artificial island called in the Maldives ?
Hulhumalé
Why are tuna stocks lower?
Warmer seas
What are the Maldives planning to become
The first carbon neutral country
Where is Sue Earles Farm?
Mappleton
What is sue earles Farm called?
Cowden farm
What are the Social, benefits of protecting Hornsea
There are social benefits of protecting Hornsea because 9000 people live there.
What are the environmental, benefits of protecting Hornsea
the environmental benefits are because there is a conservation where buildings such as St. Nicholas Church.
