Paper 2: Coastal Landscapes Flashcards
Name the three types of weathering
Biological
Chemical
Mechanical
biological weathering
Living things break down rock
Plant roots can biologically weather a rock by pushing cracks apart
Mechanical weathering
Chemical composition of rocks stays the same
Freeze thaw weathering - water expands when it freezes - when it fills the cracks, it expands, putting pressure on rock and freezing + thawing will wear down the rock
Chemical weathering
The chemical composition of rocks changes
When the climate is warm and wet, carbonic dioxide can dissolve in rain to create a ‘carbonic acid’.
The carbonic acid in rainfall hits rocks and dissolves the parts of the rock made of calcium carbonate.
This also breaks down rock
What is mass movement?
Mass movement describes the movement of rocks on a hill or cliff. These movements are caused by weathering, erosion, and gravity. Small changes over time can mean that a cliff’s centre of gravity hangs over the sea, instead of over land
What are slides?
Slides are when material moves down a slope in a straight line.
What are rock falls?
Rockfalls are when the cliff (materials) break and crumble down the cliff.
What are slumps?
Slumps are when a slip plane forms under the cliff. The cliff then slumps down in layers.
What are the two main types of wave?
Constructive and destructive
What are constructive waves?
Constructive waves deposit material on coastlines because their swash depositing things on the beach is stronger than their backwash dragging things from the beach
Constructive waves are small waves that are not very tall above the surface of the ocean
What are destructive waves?
Destructive waves are taller and more frequent than constructive waves
Destructive waves cause most of the erosion of coastlines.
Destructive waves have a stronger backwash than swash, meaning they drag more material away from the coastline than is deposited on the shore
What is deposition?
Deposition describes the sea putting (depositing) solid material from the sea onto the land on the coastline.
Constructive waves deposit material on coastlines because their swash depositing things on the beach is stronger than their backwash dragging things from the beach
How do destructive waves erode the coast?
Hydraulic power: The force of wave actually breaks the rock itself.
Abrasion: The material and rock being carried by the sea damages the coastal rock.
Attrition: The bedload collides with itself, eroding it
Features of UK climate that impact rates of coastal erosion and retreat
Rainfall
Prevailing wind
Storm frequency
Seasonality
What are the terms given to cracks and weaknesses in rocks?
Joints and faults
Name the two types of coastline
Concordant
Discordant
What type of area are headlands and bays formed in?
Areas that have alternate areas of hard and soft rock facing the sea
What type of rock has lots of cracks and joints?
Soft rock
Why does clay erode quicker than chalk?
Clay is a softer rock
Concordant coastlines
Concordant coastlines have a layer of soft rock, then a layer of harder rock, then a layer of soft rock next to each other.
Discordant coastlines
Discordant coastlines have alternating chunks of hard rock and soft rock at 90 degrees to the coast. The sea’s waves will hit both hard rock and soft rock when they meet the coast.
How does seasonality impact climate on coastal erosion and retreat?
Temperature changes and the range of temperatures that rock is exposed to can affect erosion and weathering.
E.g freeze thaw weathering
How does rainfall impact climate on coastal erosion and retreat?
At times of heavy rainfall, soil can become saturated, and mass movements may be more likely.
After heavy storms, chemical weathering may be more likely to happen.
Heavy rainfall is often accompanied by storms and destructive waves.
How does prevailing winds impact climate on coastal erosion and retreat?
The prevailing winds affect where sediment is carried.
Strong prevailing winds can lead to lots of destructive waves.
Winds from the Atlantic Ocean hit the south-west of England.
How does storm frequency impact climate on coastal erosion and retreat?
Many parts of the UK are frequently hit by storms.
If storms happened more often, then erosion and weathering would happen more quickly.
At what kind of coastline do bays form?
Discordant coastline
Over time, cliffs are eroded by destructive waves resulting in what?
Wave - cut platforms
What is left behind after cliffs retreat due to erosion?
Wave - cut platform
What is needed for headlands and bays to form?
Bands of hard and soft rock
What type of rock are headlands made of?
Resistant rock
As headlands are eroded what types of landforms can be created?
Caves
Arches
Stacks
How are caves formed?
There are cracks, joints, and weaknesses in rocks.
When cracks get wider (because of hydraulic action, abrasion or attrition), they can become large enough to create a cave.
How are arches formed?
Caves can be eroded from one side of the rock through the other.
This creates an arch.
You can see right through an arch to the other side of the rock.
Durdle Door (Dorset), Bow Fiddle Rock (Scotland), and the Green Bridge of Wales (Pembrokeshire) are the 3 most famous arches in the UK.
How are stacks formed?
When the top of an arch collapses because of gravity, a column called a stack is left behind.
What type of waves is responsible for most of the erosion that takes place at the base of cliffs?
Destructive waves
What is longshore drift?
Transports material along coastlines
How does longshore drift happen?
Longshore drift happens when waves move up the beach at an angle because of a prevailing wind direction.
What determines the angle at which the swash moves up the beach?
Prevailing wind direction
What is coastal deposition?
Coastal deposition describes the sea dropping sediment (or material) being carried by the water at the coastline. Coasts grow in size when more sediment is deposited on the coast than is lost to the process of erosion
What increases the amount of deposition?
If erosion on the nearby coast is high, then lots of rock and sand will fall into the ocean. This will increase deposition on nearby beaches.
The more sediment in the ocean, the more deposition there will be
Why are some beaches sandy and some shingle?
Sandy beaches are created by sand being deposited on the shoreline.
Sandy beaches are usually very long, side, and flat because particles of sand are very small and easy to wash back into the ocean with the backwash.
Shingle beaches are made when pebbles and shingle are deposited on the coast. Shingle and pebbles are big and hard to wash back into the ocean, so they build up (making short and steep beaches)
Why does deposition happen?
Deposition happens when constructive waves break on the shore. The sediment being carried by the sea is put (deposited) on the coastline.
This usually creates beaches made of sand or shingle in the area between the ‘high’ water mark and the ‘low’ water mark.
What are sand dune and how are they created?
Sand dunes are hills of sand created at the back of a beach.
The wind blows deposited sand up the beach. Objects like wood, driftwood or human rubbish can block the wind, leading to hills of sand.
What are spits?
Spits are piles of sand that create sheltered zones on the coast.
When the coast changes direction at an estuary (where a river meets the sea), longshore drift continues to move sediment across the inlet
Spits are the long fingers of sand sticking out from one side on a coastline. They often have marshland forming in the sheltered zone.
What are bars?
A bar is created when a spit grows across a bay.
What process transports material along coastlines?
Longshore drift
What do we call new sand dunes?
Embryo dunes
Overtime, destructive waves erode cliffs resulting in the formation of…?
Wave-cut platforms
Which coastal landforms are formed in areas where there are bands of hard and soft rock facing the sea?
Headlands
Bays
What is needed for headlands and bays to form?
Bands of hard and soft rock
What are the main processes of erosion that form a cave?
Hydraulic action and abrasion
What type of rock is Old Harry made from?
Chalk
What are the human activities on the coast?
Housing Office Agriculture Industry Coastal management
How does housing affect the coast?
More people are moving to the coast as it is more affordable than living in London
Commuters and retired are choosing to relocate coastal cities
How do offices affect the coast?
High office costs mean that many companies are also relocating
JP Morgan relocated to Bournemouth in 2015
How does agriculture affect the coast?
The price of farmland has increased greatly (£2400 per hectare in 1995 to £30000 per hectare in 2015)
This means farmers are using whatever land they can
Including wetlands and marsh which are vital for wildlife
This farmland could also be at risk of sea level rise
How does industry affect the coast?
Heavy industries on the coast negatively impact the visual landscape
This can prevent tourism to certain areas
How does coastal management affect the coast?
Can heavily impact the appearance and processes of the coast
Name types of hard engineering
Sea walls
Groynes
Gabions
Revetments
Name types of soft engineering
Beach nourishment
Dune regeneration
Marsh creation
Explain how recently Holistic coastal management has been adopted
Coastlines are managed as a whole, rather than as individual elements - this is known as Integrated Coastal Zone management
This requires a Shoreline Management Plan to be created
Land is assessed and 1 of the 4 options in chosen for each part of the coast
1) hold the line 2) advance the line 3) strategic realignment 4) do nothing
What are sea walls?
Concrete walls that are placed at the foot of a cliff to prevent erosion. They are curved to reflect the energy back into the sea
Advantages of sea walls
Effective at protecting the base of the cliff.
Sea walls usually have promenades so people can walk along them
Disadvantages of sea walls
Waves are still powerful and can break down and erode the sea wall.
Expensive - approximately £2,000 per metre
What is rock armour?
Large boulders placed at the foot of a cliff. They break the waves and absorb their energy
Advantages of rock armour
Cheaper than a sea wall and easy to maintain.
Can be used for fishing
Disadvantages of rock armour
They look different to the local geology, as the rock has been imported from other areas.
The rocks are expensive to transport
What are gabions?
Rocks are held in mesh cages and placed in areas affected by erosion
Advantages of gabions
Rocks are held in mesh cages and placed in areas affected by erosion
Advantages of gabions
Cheap - approximately £100 per metre.
Absorb wave energy
Disadvantages of gabions
Not very strong.
Look unnatural
What are groynes
Wooden or rock structures built out at right angles into the sea
Advantages of groynes
Builds a beach - which encourages tourism.
They trap sediment being carried by longshore drift
Disadvantages of groynes
By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere.
They look unattractive
What is beach nourishment?
Sand is pumped onto an existing beach to build it up
Advantages of beach nourishment
Blends in with the existing beach.
Larger beaches appeal to tourists
Disadvantages of beach nourishment
Needs to be constantly replaced.
The sand has to be brought in from elsewhere
What is dune regeneration/ nourishment ?
Marram grass planted on sand dunes stabilises the dunes and helps to trap sand to build them up
Advantages of dune regeneration
Relatively cheap.
Maintains a natural-looking coastline
Disadvantages of dune regeneration
Can be damaged by storm waves.
Areas have to be zoned off from the public, which is unpopular
What will happen if sea levels rise?
Beaches and spits will be eroded faster
Current sea defences will becomes useless and many properties will be lost
What has happened in Happisburgh?
The land was not valuable enough to justify renewing coastal defences
The town of 850 people had not been protected since 1995
Why is Happisburgh vulnerable?
1) Cliffs made from soft sand on top of clay - they were formed during the last ice age and are easily eroded - this is causing rapid cliff collapse
2) Long Fetch in North Sea generates powerful storm waves
3) Narrow beaches offer little protection as they don’t reduce the power of the waves
4) Sea level rise and climate change
What are the impacts in Happisburgh?
Loss off property and business (Such as Tea Shop)
The value of properties has decreased greatly
What is cost benefit analysis?
Looking at all the costs of a project, social and environmental as well as financial, and deciding whether it is worth going ahead
What is the significance of Happisburgh?
Destructive waves will cause the cliff to erode and collapse, it is low lying the rock is sedimentary so it will erode faster due to being soft rock
Attempts to reduce coastal erosion in Happisburgh
Timber groynes were built in the 1950s but were destroyed by waves by 2000
Thousands of tonnes of cliff materials get washed away
Local people raised money to create more rock armour
Happisburgh- impacts upon people and environment due to destructive waves
Neighbours have abandoned their house away due to cliff edge being 40 metres away
Retreating by an average 10-15 metres
30 buildings have been destroyed
