Coasts Flashcards
What is the case study example for wave cut platform?
Southerndown, South Wales
What is the case study example for cave, arch, stack and stump?
Old Harry Rocks, Dorset
What are the steps to forming a wave cut platform?
1) Weather weakens the top of the cliff
2) The sea attacks the base of the cliff forming a wave cut notch
3) The notch increases in size, and the cliff collapses
4) The backwash carries the sediment toward the sea forming s wave cut platform
5) Process continues as the cliff continues to retreat
What are the steps to forming a cave?
1) The sea erodes away at the headland and the bottom crumbles off, original fault lines
2) The sea erodes it with abrasion and hydraulic action which makes a cave as its being eroded from one side
How is an arch formed?
After a cave is formed, weathering and erosion has broken through the cave to make and unstable arch- from both sides
How is a stack and stump formed?
The bottom of the arch cant hold its weight and vegetation breaks through the rock so it collapses and forms a stack
These stacks have 360 degrees of attack from the sea and form stumps
What is the case study example for a headland and bay?
Swanage, Dorset
What is the case study example for soft rock slumping?
Cliffs of Norfolk
What are the steps to forming a headland and bay?
1) Three strips of land- hard rock, soft rock, hard rock
2) Sea erodes all parts of the cliff
3) The soft rock erodes faster than hard rock, it retreats
4) Retreated soft rock cliffs form an arc shape called the bay, and the headlands are the cliffs sticking out to sea
5) Caves, arches, stacks and stumps starts to form
What are the five factors that cause soft rock slumping?
- Base of the cliff is eroded
- Weathering weakens the rock
- Heavy rain saturates the cliff top and adds weight
- Water flows through permeable rock and erodes it
- Building on the top of the cliff adds weight, pushes down on the weak cliff
What is the case study example for a spit?
Easthead Spit, Hampshire
What is the case study example for a bar?
Slapton Key, Devon
What are a positive and negative effect of longshore drift, for named locations?
Easthead Spit- 90m wide beaches protect settlements being flooded, tourist attraction, protected habitats for animals
Clarence Pier- 2m left of beach, lowered income from tourism, land behind beach has to rely on manmade methods of coastal management to protect land
What are the steps to longshore drift?
1) The prevailing winds hit the sea at an angle and the waves are at that angle
2) Causes the swash to be at and angle to the sea, and the deposition is at the side
3) However the backwash brings it back at 90 degrees to the sea, makes a zig zag
4) Constructive waves moves the sediment across the shore, so sediment deposition is moved from one end of the coast to the other, in the prevailing wind direction
What are the steps to forming a spit?
1) Longshore deposits sand and shingle to one side of the coast, by the headland
2) As it gets to the end it keeps building up at the headland, the prevailing wind direction changes so longshore drift changes direction and forms a recurved edge
3) Between the recurved edge and headland, sea water gets trapped and creates a salt marsh
What are the steps to forming a bar?
1) The spit has continued to form between two headlands, no prevailing wind direction change
2) The old bay has been filled with trapped sea water and becomes a lagoon
3) Later the lagoon becomes filed with deposition
What are case study examples for cliff recession?
Landsend, Cornwall- HARD ROCK
Holderness, Yorkshire- SOFT ROCK
What are the four causes of cliff recession?
- Eroded due to soft rock slumping, sea undercuts the cliff and the cliff face falls off
- Vegetation digs its roots into the rocks
- Rainwater forces its way into cracks and adds weight
- Rock is eroded which makes the headland form caves, arches, stacks and stumps
What are the six effects of cliff recession?
- Houses close to the cliff can fall in, expensive
- To prevent it happening you have to buy expensive sea defenses
- Businesses fail because they lose land and properties in it
- Sudden cliff collapse could crush people on the beach
- Loss of coastline, habitats and landmarks, no tourism
- Increased abrasion from more debris in sea
What are some case study facts and figures for Landsend, Cornwall?
- Mostly made from granite
- Slow rate of erosion
- Large fetch of 7,200km, powerful waves
- Only recedes a few feet per annum
What are some case study facts and figures for Holderness, Yorkshire?
- Mostly made from boulder clay (ice sheets)
- Fastest eroding coastline in the UK
- Small fetch of 650km between Norway, potential to accumulate large waves
- Erodes at 30 feet per annum
- Groynes and other sea defenses have been used
What can be done to protect and plan against coastal flooding? (HIC example)
Example- England, London
Protect- Leave open space allowing water to spread with no damage, 520m long barrier, protects 125km squared of land which holds houses and hospitals
Plan- Leave open space, build houses far from it, monitor houses in danger, compensate their losses
What can be done to protect against coastal flooding? (LIC example)
Example- Bangladesh (of course)
Protect- Build flood shelter on stilts, more embankments and concrete buildings, afterwards they can get water seeds and food imported to prevent starvation
What can be done to predict coastal flooding?
Monitor wave height an frequency, then when the height and frequency is above average then you know the coats will be effected, early warnings
Define hard engineering
Strategy put in place to STOP coastal erosion and manage effects
Define soft engineering
Reaction to the effects of coastal erosion and/or repairs them
List the soft engineering strategies, and the hard engineering strategies
Soft engineering- Groynes, Beach nourishment
Hard engineering- Sea wall, Gabions, Rock armour, Breakwater
What are the processes of erosion and biological weathering?
Hydraulic action
Corrosion
Attrition
Abrasion
Biological weathering
Acid rain
What are some case study facts and figures for coastal management at Swanage?
Beach nourishment- 90,000m cubed of sand, June 2006, cost £2.2million
Sea walls- 1.8km of concrete, expensive
Groynes- 1.8km of groynes
Rock armour- placed at cliff bases in 1980s
What happened at Durlston?
Overnight, 10m of cliff faces disappeared
- Additional drainage was installed
- The cliff face has been regraded, gravel at cliff base
- Granite rock armour has been added to the base of the cliff and stops undercutting
Properties of a destructive wave
- Strong backwash
- Weak swash
- High amplitude
- Causes erosion
- Higher frequency than constructive
- Larger fetch
Properties of a constructive wave
- Weak backwash
- Strong swash
- Low amplitude
- Causes deposition
- Lower frequency than destructive
- Smaller fetch
