Coasts Flashcards
Coastal Erosion
- Hydraulic action: waves force air into cracks and the rocks break up into pieces.
- Corrasion/Abrasion: waves throw pebbles against cliffs wearing away at them.
- Solution/Corrosion: chemicals in the saltwater dissolve those in the rocks causing them to break up.
- Attrition: pebbles in the water hit off of each other, becoming more rounded.
Cliffs and Wave-cut Platforms
- Waves are thrown against the base of the cliff and due to the processes of hydraulic action, solution/corrosion, and corrasion/abrasion they wear away the cliff and a wave-cut notch is formed.
- Eventually, the cliff becomes unsupported and collapses into the sea.
- The cliff retreats and leaves behind a wave-cut platform which is visible at low tide.
Headlands and Bays
- When rock along a coastline is formed in alternating bands of different rock types (sandstone and clay) which meet the coast at right angles.
- The soft rock (clay) is eroded more quickly than the hard rock (sandstone) and so it erodes backward faster creating sheltered bays which may have beaches.
- The harder rock (sandstone) areas are more resistant to erosion and jut out into the sea to form exposed headlands.
Caves, Arches, and Stacks
- Waves (through the processes of hydraulic action, abrasion/corrasion, and solution/corrosion) attack the headland and erode at any type of weakness.
- These lines of weakness are enlarged by the processes and develop into caves.
- The caves are deepened and widened on both sides and eventually the sea cuts through the headland, creating an arch.
- The rock on top of an arch becomes very weak and collapses through, leaving a stack.
- The stack erodes at the bottom and eventually topples, leaving a stump.
- As the headland retreats, the gently sloping land at the bottom of the retreating cliff is called a wave-cut platform.
Longshore Drift
- A pebble or sand particle moves to the beach diagonally in the swash (the direction varies depending on which was the prevailing wind is blowing from)
- Then the backwash and gravity carry the particle back down the beach, into the open water.
- This process is repeated and the particles move along the shoreline.
Spits
- When the coastline changes direction, longshore drift continues to carry material into the open water.
- Over time the material will build up and rise above the water (these can only form in shallow areas of water) this is called a spit.
- The spit cannot spread all the way across the bay as a rivers estuary prevents a build-up of sand.
- The spit has a hooked end because of a secondary wind and wave direction which causes the wave to strike from a different direction.
- The spit creates an area of calmer water behind it. A lagoon, salt marsh or dry land can form here.
- If a spit reaches out and joins onto an island, it is called a tombolo.
Sandbars
- When a spit extends out far across a bay and blocks it off from the sea.
- A lagoon is formed (the water cut off)
- A sandbar is less likely to form over a river mouth as the estuary prevents this.
The Dorset Coast Land Uses
Farming
-Warm sunny climate.
-Fertile clay soils.
-Flat land.
-Oyster and mussel farming takes place on Poole harbor.
Industry
-Oil (sixth largest oil field is located ar Poole Harbour)
-Quarrying (high-quality limestone is quarried n the Isle of Portland)
-Sheltered harbors provide direct access to the English channel which is a major shipping route from imports and exports to and from Europe.
-The Bournemouth conference center is a service industry which helps provide year-round jobs
Tourism
-Many resorts (Swanage) providing tourist facilities such as restaurants.
-Beautiful beaches (Chesil Beach) enable watersports and sunbathing to happen.
-There are a number of historic attractions (Corfe Castle)
-Activities are run such as fossil hunting are set up to allow educational groups to visit.
-Coastal footpaths allow people to enjoy the scenery and take photographs.
-There is also lots of wildlife to see as there are a number of different habitats such as lagoons.
Renewable Energy
-There is potential to generate electricity through wind and wave power in the area, in addition to nuclear power stations as there is plenty of seawater to cool the reactors.
The Dorset Coast Land Use Conflicts
Locals versus Tourists
-Problem: Increased traffic congestion especially on honeypot sites.
Solution: A steam railway from Swanage to Corfe allows tourists to leave their cars and travel via public transport.
-Problem: Increased traffic leads to a rise in noise and air pollution.
Solution: Train lines, bus routes, cycle paths and boat trips to reduce congestion.
-Problem: Unsightly footpaths and erosion of sand dunes because of the number of visitors.
Solution: The National Trust and Dorset Wildlife Trust buy and manage land to keep it in good shape.
-Problem:Increased litter and fires especially on beaches.
Solution: Local authorities fine for litter dumping ans voulentary litter picking is arranged.
-Problem: Fragile wildlife habitats are destroyed by walkers.
Solution: Replanting of marram grass to conserve vegetation.
-Problem: Wildlife on beaches is desturbed.
Solution: Nature Reserves such as Brownsea Island have been created to protect wildlife.
-Problem: Second home ownership increases and so local first time buyers struggle to get onto the property ladder.
Solution: National government offer help to first time buyers through affordable home ownership schemes
Tourists versus Tourists
-Problem:There are about lots of different land uses going on and they conflic with each other sometimes
Solution: we can zone off areas to ensure that different activities are kept apart.
-Problem: Tourist facilities auch as cap sites spoil the look of the coast.
Solution: World Heratage sites allows local authorities to protect the coast from over-development.
-Problem: Swimmers and sunbathers may be disturbed by water sports.
Solution: An aquatic management plan encourages quiet areas (zones)
-Problem: Anglers may be disrupted by water sports.
Solution: Public education schemes, guide books and leaflets are made to encourage responsibe tourism
-Problem:As many as 20,000 visitors visit Studland Beach on a hot day in the summer.
Solution: Local authorities comply with the EU blue flag scheme on beach quality.
-Problem: Visitors dogs can dirty the beaches and footpaths.
Solution: Poop scoop schemes have been set up to stop dogs fouling on the beach
Methods of Coastal Protection
-Seawall: Absorbs wave energy to protect the cliff foot. When the seawall reflects the wave, the backwash drags the sand out and leaves the wall open to erosion. Eventually, it collapses. They are also expensive and attractive.
-Rip-rap: Also known as rock armor, absorb wave energy instead of the cliff. They are unattractive and can be used as the material for attrition.
-Revetement: Sloping wall made out of wood or concrete to absorb wave energy. The wood can rot.
-Beach building: This involves importing sand and building a beach. The problem is that it is not permanent.
-Groynes: These trap sand that would otherwise be removed by longshore drift. The problem with these is that sand won’t be level and these groynes can rot as they are made of wood.
-Offshore breakwater: This creates a false headland made of concrete to absorb wave energy instead of the shore. These work well.
All of these measures are temporary
