Lithosphere Flashcards
(37 cards)
Define hydraulic pressure.
The force of waves compressing air in the cracks of a cliff.
Define abrasion (coastal)?
Large waves hurling beach material against a cliff.
Define attrition.
When waves cause rocks and boulders on the beach to bump into each other and to break up into smaller particles.
Define corrosion.
When salts and other acids in seawater slowly dissolve a cliff.
How do headlands and bays form?
When destructive waves erode the areas of softer rock of a cliff a bay is formed.
Headlands are what are left as the resistant rock that wasn’t eroded. This leaves the headlands more exposed and they become more vulnerable to erosion while also protecting the bays from destructive waves.
How do wave-cut platforms form?
When waves are at their highest they undercut the foot of a cliff to form a wave-cut notch. This continues until the cliff above the notch is left unsupported and collapses. As this repeats the cliff retreats and gradually increases in height. The gently sloping expanse of rock marking the foot of the retreating cliff is a wave-cut platform.
How do stacks form?
A joint or fault in a cliff is where the start of the formation takes place. Hydraulic pressure quickly compresses the air inside it and widens the joint. It keeps getting wider until a cave is formed. The cave keeps getting eroded until it is eroded the whole way through and forms an arch. As the arch continues to be eroded the roof of the arch may become so unsupported that it collapses and falls into the sea. This leaves an isolated pillar in the water called a stack. Stacks will continue to be eroded until it is a stump.
What is longshore drift?
When waves approach the beach at an angle due to the direction of the prevailing wind, material is carried up the beach. This is called the swash. It then carries material directly back into the ocean in the backwash. Wooden groynes slow down this movement by keeping material on the beach.
What is a spit?
When a coast curves inwards and away from its previous direction longshore drift continues on its course. At the position of this change of direction, the longshore drift meets with the sea and is forcefully slowed and it drops its load at that point. This continues and a mound begins to form. This mound eventually surfaces and is now an extension of the beach. As the extension grows longer a spit is formed.
How do tombolos form?
When a spit extends outwards to join an offshore island it is called a tombolo.
How do bars and lagoons form?
When a spit develops into a bay into which no major river flows it may be able to build across that bay which is called a bar. The trapped water behind the bar is called a lagoon.
How can the land around Lulworth Cove be used?
For local estate, locals, farmers and the ministry of defense.
What is the conflict at Lulworth Cove between the Ministry of Defense and Tourists, what solutions are there and how effective are they?
Tourists are denied access to large areas around Lulworth Cove for much of the year because of necessary military activity.
Tourists get annoyed because there are access difficulties when roads are closed and restrictions impose on walkers.
The Ministry of Defense get annoyed because tourists do not always respect signage and disturb military activity.
Solutions include:
- Permitting access to the ranges at weekends and busy holiday periods.
- Keeping roads open during the busiest holiday periods.
- Reducing noise levels associated with firing at these times.
These solutions are effective as:
- The M.O.D has said that limiting public access has helped preserve the area and restricting development on the area.
- The limitations mean that some parts of the coastline are available to people who are prepared to walk.
These solutions are ineffective however as:
- There are fewer visitors due to access problems.
What is the conflict at Lulworth Cove between
the Locals and Tourists, what solutions are there and how effective are they?
Locals get annoyed because:
- The road to Lulworth Cove is a dead end and is narrow so congestion is an inevitable thing.
- Inconsiderate parking causes problems for locals.
- The character of the village is spoiled by tourists, vehicle noise and litter.
- Litter creates a danger to wildlife and is an eyesore.
- The holiday park is unsightly.
- There is an abundance of tourist shops which do not help with keeping the character. Shops raise prices during peak times.
- Many houses are bought as second homes and lie empty for most of the year. House prices become inflated making it hard for locals to purchase property.
The tourism industry however provides employment for locals and brings money and improves services for the local economy.
Solutions include:
- Managing a car park which accommodates over 500 vehicles in overflow areas. It is surfaced in chalk rubble.
- Constructing a roundabout to provide easy access to the car park.
These are effective as:
- The estate has also has made a bus service available from local railway stations to encourage people not to come by car.
- Car park revenue is used for local facilities.
These are not effective as:
- Car parking charges are high. Visitors can avoid this by parking inconsiderate.
- The chalk in the car park stands out against the green surroundings and it creates huge amounts of dust.
What is the conflict at Lulworth Cove between
the Farmers and Conservationalists, what solutions are there and how effective are they?
Farmers want more cattle to get more income, but conservationalists see this as more grass being eaten. The area is a world heritage site, an area of natural beauty and a site of special scientific interest so this is disrespecting that. Footpaths are eroded quickly, the grassland vegetation is very fragile and trampling of the soils mean the soils are very easily eroded.
Solutions include:
- Allowing free admission to the Heritage centre which has things like interpretative boards that encourage environmental conservation.
- The countryside ranger service employs two full time rangers who carry out a wide range of coastal management duties.
- Maintenance of footpaths, replanting of plants, steps have been put in place on steep parts to avoid trampling.
These are not effective because:
- Resurfacing encourages more walkers which cancels out resurfacing efforts.
- The whiteness of the path is an unnatural white scar on the landscape.
- People sometimes avoid timber steps as they’re unnatural.
What is the pathway from snow to ice?
Snow -> Firn -> Nevee -> Ice
What is the zone of accumulation and the zone of ablation?
The zone of accumulation is where the snow accumulates and is found at the top of a glacier.
The zone of ablation is where the snow leaves the glacier or melts. This is found at the end of a glacier.
What are the three main ways glaciers flow?
Internal flow
Basal sliding
Bed deformation
What is internal flow?
It is when weight and pressure causes the ice to realign in the direction of the ice’s movement making it easier for them to slide and for the glacier to go downhill.
What is basal sliding?
It is when the glacier wants to move over a rocky bed so water goes between the rocks and the glacier and this lubricates the area between them making it easier for the glacier to move.
What is bed deformation?
When the glacier moves due to the rock material at the bottom of the glacier deforming. This usually happens when the rock is weak. This is also caused by pressure.
What is plucking?
When rocks and stones freeze to the base and the sides of the glacier and are plucked from the original cliff or patch of land it was on leaving a jagged landscape.
What is abrasion (glaciation)?
When rocks are embedded in the base and sides of the glacier and they are rubbed against the ground or the rock faces as the glacier moves. The landscape is worn away as a result.
What is freeze-thaw action?
Water becomes trapped in a joint. It freezes when it is cold enough and expands by 9-10%. This puts pressure on the rock. The ice melts when its warm enough, this process is repeated which weakens the rock until it shatters into angular fragments.
