Flashcards in Coastal Landscapes in the UK Deck (21):
Arch and how do they form.
A wave eroded passage through a small headland. This begins as a cave which is gradually widened and deepened until it cuts through.
Bars and how they form.
Long shore drift may cause a split to grow right across a bay, trapping a freshwater lake (or lagoon) behind it. This feature is causes a bar.
Beaches and how they form.
They are mostly found in sheltered bays. The waves entering are constructive waves. Much of the south coast of england has pebble beaches. These high energy enviroments wash away finer sand and leave behind the larger pebbles. These come from nearby eroded cliffs or are deposited onshore.
describe the process of long shore drift
Waves follow the direction of the prevailling wind. They usually hit the coast at an oblique angle. The swash carries materials up the beach in the same direction of the waves. The backwash caries the materials down the beach at right angles back towards the sea. Overtime material zig-zags along the beach.
Splits and how they form.
A split is a long narrow finger of shingle or sand jutling out into the sea from land. It forms where there is significant long shore drift. When the coast line changes orientation and bends sharply, sediment is deposited out to sea. As it builds up, it starts to form an extension from the land. Strong winds and tidal can cause the end of the split to become curved which forms a recured end. In the sheltered water behind the split, deposits of mud build up. An externsive salt marsh forms as vegetation starts to grow in the emerging muddy islands. Salt marshes are extremely important to wild life habitats and over wintering grounds for migraining birds.
Stacks and how they form.
Isolated pillar of stump left when the top of and arch has collapsed.
Stumps and how they form.
When a stack is eroded by atteition overtime.
Wave-cut platform and how they form.
weather weakens the top of the cliff and the sea attacks the base forming a wave cut notch. The backwash caries the rubble towards the sea forming a wave-cut platform.
What are the erosional landforms?
Cliffs,Wave-cut platform, Cave, Arch, Stack, Stump
what are the processes of transportation
what is Abrasion/Corrasion
The bed and banks are worn down by the river load. Sometimes they throw the particles at high veloity.
what is attrition
Waves smash rocks and pebbles on the shore into each other which causes them to break and become smoother.
What is Hydraulic Action
The force of water against the bed and banks. It traps air in the rocks and puts pressure on the rock, which weakens them.
What is managed retreat?
When a decision is made to no longer follow a 'hold a line' strategy for managing coastal flooding and erosion. People are moved out, building demolished then a breach is made in existing sea defences so the sea inundates/floods the land and creates new intertidal habitats.
what is saltation
Load is bounced along the sea bed, eg small pieces of shingle or large sand grains. Currents cannot keep the larger and heavier sediment afloat for long periods.
what is solution
The acid in the sea water dissolves some rock types like chalk/limestone.
What is solution(transportation)?
Minerals dissolved in the sea water are carried in solution. They are not visable and can come from cliffs made from chalk/limestone. Calcium carbonate is carried along in the solution.
what is suspension
Small particles are carried in the water eg splits and clay, which can make the water cloudy. Currents pick up large amounts of sediment in suspension during a storm, when strong winds generate high energy waves.
what is the different types of erosion
what is traction
pebbles and larger sediment is rolled along the sea bed