Coastal Landscapes in the UK

Question 1

What is mechanical weathering?

Answer 1

The breakdown of rock without changing chemical composition

Question 2

What is freeze-thaw weathering?

Answer 2

Mechanical - temperature alternated above/below freezing. Water in cracks freeze + expand, puts pressure on the rock. They melt. Repetition widens cracks + breaks the rock

Question 3

What is chemical weathering?

Answer 3

The breakdown of rock by changing chemical composition

Question 4

What is carbonation?

Answer 4

Chemical - rain has CO2, makes it a weak carbonic acid, carbonic acid reacts with rock containing calcium carbonate (e.g limestone), so they get dissolved.

Question 5

What is mass movement?

What does it cause?

When is it more likely to happen?

What is a scarp?

Answer 5

The shifting of rocks/loose material down a slope

Coasts retreat rapidly

When the material is saturated (lubricated + heavy)

A steep ‘cut’ in the slope

Question 6

What is a slide?

What is a slump?

What is a rockfall?

Answer 6

Material shifts in a straight line down the slope

Material rotates along a curved slip plane

Material breaks up and falls down the slope

Question 7

Describe destructive waves

Answer 7

• Larger backwash than swash
• High frequency
• High and steep
• Remove material

Question 8

Describe constructive waves

Answer 8

• Larger swash than backwash
• Low frequency
• Low and long
• Material is deposited

Question 9

What are the three erosional processes?

Answer 9

• Hydraulic power - waves compress air in rocks, puts pressure on, breaks the rocks
• Abrasion - eroded particles in water rub against rock
• Attrition - eroded particles in water collide, become smoother + rounder

Question 10

Describe longshore drift

Answer 10

Waves follow direction of prevailing wind, hit the coast at an oblique angle, swash carries material up beach at an angle, backwash carries it down the beach at right angles, over time, material zig-zags across beach

Question 11

What is a concordant coastline?

Answer 11

Alternating bands of soft/hard rock are parallel to coast

Question 12

What is a discordant coastline?

Answer 12

Alternating bands of soft/hard rock perpendicular to coast

Question 13

How are headlands and bays formed?

Answer 13

Discordant coastline, soft rock is eroded faster, forms bay with a gentle slope. Hard rock is eroded slower, forms headlands with steep sides

Question 14

How are stumps formed?

Answer 14

Headlands often have weaknesses. Hydraulic power + abrasion largens the cracks until a cave is formed.

Continued erosion deepens the cave until it breaks through = arch

Erosion wears away rock supporting the arch, so the roof collapses, forming a stack

Bottom of the stack is eroded, it collapses = a stump

Question 15

How is a wave-cut platform formed?

Answer 15

Waves cause erosion at the bottom of a cliff, forming a wave-cut notch
Repeated erosion makes the notch become unstable so it collapses
The collapsed material is washed away, process repeats
The cliff retreats, leaving a wave-cut platform

Question 16

How are sand beaches formed?

Answer 16

Formed by low-energy constructive waves, small particles can be moved by weak backwash, making a flat + wide beach with a long, gentle slope

Question 17

How are shingle beaches formed?

Answer 17

Formed by high-energy constructive waves, sand particles are washed away leaving larger shingle, shingle is built up to make a steep slope on a steep and narrow beach

Question 18

How are spits formed?

Answer 18

Form at sharp bends in the coastline, longshore drift moves sediment past the bend into the sea
Strong winds can curve the end, forms a recurved end
Area behind spit is sheltered, material accumulates making a mud flat or salt marsh

Question 19

How are bars formed?

Answer 19

A bar is when a spit joins two headlands together, bay gets cut off from the sea, forms a lagoon

If the coast has a gentle slope, friction with seabed makes waves slow down, deposits sediment offshore, makes a bar not connected to coast (offshore bar)

Question 20

How are sand dunes formed?

Answer 20

Sand deposited by longshore drift is moved up the beach by wind = sand dunes, obstacles decrease wind speed = deposition
Small embryo dunes are colonised by plants, roots stabilise sand so more accumulates there
They form foredunes and then mature dunes.
Dune slacks are pools in hollows between dunes

Question 21

What are some landforms on the Dorset coast?

Answer 21

• Durdle Door = arch made of limestone on concordant coastline
• Lulworth Cove = bay formed by a band of clay behind limestone
• Chesil beach = tombolo (type of bar)
• Swanage/Studland bay = bays made of clay + sandstone, in between is the Foreland (headland made from chalk)
• Old Harry (stack) and Old Harry’s wife (stump)

Question 22

What are some hard engineering defences to protect the coastlines?

Answer 22

• Sea wall - reflects waves to sea, prevents erosion + flooding BUT expensive + backwash erodes under wall
• Gabions - wall of wire cages filled with rocks, absorb wave energy, cheap, easy BUT ugly + wire corrodes
• Rock armour - boulders piled up, absorb wave energy, cheap BUT can be moved so must be replaced
• Groynes - fences prevent longshore drift, make wider beaches so slow the waves (protects from flooding + erosion) BUT starve beaches further down coats of sediment = narrower = greater erosion

Question 23

What are some soft engineering defences to protect the coastlines?

Answer 23

• Beach nourishment / reprofiling - sediment from elsewhere added to beaches or beach flattened, creates wider beaches = more protection BUT can kill organisms, expensive + has to be repeated
• Dune regeneration - nourish dunes or add plants, dunes make a barrier = protection, stabilisation is cheap BUT protection limited to small area, nourishment is expensive

Question 24

How much of Lyme Regis’ coastlines is protected using hard engineering and why?

Answer 24

1km because:
- population = 3600 but 500,000 tourists annually
- 900m of road would have been lost
- local economy depends on tourism

Question 25

What coastal defences have been used in Lyme Regis?

Answer 25

• Rock armour on eastern sea front
• beaches replenished on the town front
• drainage systems improved to reduce water build-up
• 390m of sea walls / rock armour protects roads

Question 26

What were the positive effects of coastal defences in Lyme Regis?

Answer 26

• increased trade of up to 20%
• rock armour protects the harbour + boats inside
• people feel more secure buying property

Question 27

What were the conflicts to coastal defences in Lyme Regis?

Answer 27

• more tourists = traffic, litter + noise pollution
• defences stop fossils being exposed
• very expensive for a short-term solution that could need rebuilding