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Geography > Coasts > Flashcards

Coasts Flashcards

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1
Q

What are the two types of waves?

A

Destructive

Constructive

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2
Q

Describe a destructive wave

A

Formed by strong winds

Weak swash and a strong backwash

Causes erosion- destroys beach

High energy and frequency

Short wavelength, tall

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3
Q

Describe a constructive wave

A

Gentle wave

deposit beach material- builds up beach

Strong swash and weak backwash

Low energy and frequency

Long wavelength and height

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4
Q

What is meant by the fetch?

A

The distance the wind blows over the surface of water

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5
Q

When do waves break?

A

When they reach shallow water

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6
Q

What is the swash?

A

The water that moves up the beach

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7
Q

What is the backwash?

A

Water which moves down the beach

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8
Q

Hydraulic action

A

The force of waves crashing into cliffs. Air trapped in the cracks is compressed which breaks up the rock

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9
Q

Abrasion

A

Waves hurl sand and pebbles against the cliff which wear the land away

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10
Q

Solution (corrosion)

A

Salt water dissolves rocks made of calcium carbonate

Eg limestone

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11
Q

Attrition

A

Pebbles are rolled back and forth. They collide together which makes them smaller and more round eventually Turing them into sand

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12
Q

Describe the process of longshore drift

A

Longshore drift- the process which transports material along the coastline in zigzags

Waves approach the coast at an angle because of the direction of the prevailing winds

The swash of the waves carries material up the beach at an angle by saltation and traction

The backwash the flows back to the sea in a straight line at 90 degrees

Continual swash and backwash transports material side ways along the coast.

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13
Q

How are beaches formed?

A

When constructive waves lack sufficient energy to transport material
Constructive waves build up the beach

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14
Q

What is a cliff?

A

A steep rock face

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15
Q

How are wave cut platforms formed?

A

Rock are hurled by the waves at the base of the cliff

undercuts the cliff creating a wave cut notch

Above the notch, an unstable overhang will form and in time, it will fall into the sea because of pressure and gravity

This provides more material for abrasion

Process continues and overtime the cliff retreats back

This leaves behind a wave cut platform which can only be seen at low tide

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16
Q

What is a headland?

A

An area of land that juts into the sea and is formed out of harder more resistant rock

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17
Q

What is a bay?

A

Formed between headlands. Formed by the erosion of softer rock. Beaches are often formed in more sheltered bays.

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18
Q

What effects the size of a wave?

A

Strength of the wind

Fetch - distance the wave can travel uninterrupted

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19
Q

What are spits and how are they formed?

A

A spit is a landform resulting from the deposition of sand or shingle through the process of longshore drift

Material is moved along the coastline through swash and backwash until it reaches a headland or a river mouth

The process of longshore drift continues in the same direction, taking material out to sea and extending the beach

The end of the spit will often be hooked if the wind changes direction

Mudflats and salt-marshes form behind the spit as it is sheltered from the sea

EXAMPLE- Spurn Head, Yorkshire

20
Q

What is a bar and how is it formed?

A

A bar is a ridge of sand and shingle, which has joined 2 headlands, cutting off the bay.

It is formed when a spit grows across the whole bay, through the process of longshore drift

Behind the bar, a lagoon is created

Overtime, the lagoon will become filled in by decomposition

EG SLAPTON LEY - DEVON

21
Q

What and how is a tombolo formed?

A

A ridge of sand and shingle joining the mainland to an island

Created through the process of longshore drift and formed when a spit continues to grow until it reaches an island

EG ST MICHAEL’s MOUNT - Cornwall

22
Q

Describe how caves arches stacks and stumps are formed?

A
  1. A Lange crack opens up in a headland through hydraulic action
  2. The crack grows into a cave by hydraulic action and abrasion
  3. The cave becomes larger
  4. The cave breaks through the headland forming an arch
  5. The arch is eroded and collapses
  6. This leaves a tall rock stack
  7. The stack is eroded forming a stump
23
Q

Give an example of physical weathering and describe it

A

Freeze thaw action

Water enters cracks in rocks

It freezes and expands

Ice then thaws

Parts of the rock breaks up

24
Q

Name a type of chemical weathering and describe it

A

Spray for the sea

salt causes some rocks (carbonates) to break down

25
Q

Name a type of biological weathering and describe it

A

Plant roots

Plant roots grow into cracks in rock

Breaks and weakens the rocks

26
Q

CASE STUDY- Coastal tourism

A

Dorset coast

  • Jurassic coast world heritage site
  • Holiday resorts - eg Bournemouth
  • durdle door - arch
  • old Harry stack
27
Q

What are some issues for people living in coastal areas?

A
  • flood defences disturb view
  • farm land lost due to flooding
  • flooding causes deaths
  • erosion causes houses to collapse
  • prablems with sewage and pollution
28
Q

When are waves created?

A

When wind blows over the surface of the sea

29
Q

What is hard engineering?

A

Uses structure to control coastal processes

Expensive

Unsustainable

High impact on environment

30
Q

What is soft engineering?

A

Works with nature

Less expensive

More sustainable

Less of an impact on the environment

31
Q

Examples of hard engineering strategies

A

Groynes- wooden barriers that prevent longshore drift so beach builds up 😀 beach still accessible 🙁no deposition further down coast- erodes faster

Sea wall- concrete wall reflects energy of the wave 😀 long life span 🙁expensive

Gabion or rip rap - cages of rock/ boulders absorb the waves energy 😀 cheap 🙁will need replacing

32
Q

Examples of soft engineering strategies

A

Beach nourishment- beach material replaced with sand from sea bed
Managed retreat- areas of the coast are allowed to erode naturally. Usually areas of low value land

33
Q

CASE STUDY- cliff collapse and impacts

A

The holderness coast

  • North east England, between Flamborough Head and Spurn Head
  • 2 metres of coast lost a year due to erosion of soft boulder clay material
  • Over 60,000 tons of rock armour, 2 groynes, rollback policy- sites moved 400m from coast
  • Industry at Easington is being threatened as gas terminal is too close to the sea
  • Farmers losing profit as land falls into sea
  • Properties along the coast have lost their value
  • Tourism trade is diminishing as facilities close down
  • However, land forms created as a result of erosion attract visitors-tourism
34
Q

What is a simple definition of longshore drift?

A

The transportation of particles along the coastline

35
Q

What is holistic approach?

A

When you are interested in lots of different methods

36
Q

How does hydraulic action erode a cliff?

A

The force of the wave traps air in cracks which builds up pressure and wears the rock away.

37
Q

What leads to cliff retreat?

A

Undercutting notch

38
Q

CASE STUDY- LEDC, impact of rising sea levels

A

Bangladesh

Low lying country which already suffers serious problems from coastal flooding

Large, poor population makes problem worst

spread of disease- cholera

2007-2.2 million acres of damaged crop land

Climate change is making flooding worst

39
Q

Give an example of a spit?

A

Spurn Head, Yorkshire

40
Q

Give an example of a bar

A

Slapton Ley, Devon

41
Q

CASE STUDY- Coastal management

A

Happisburgh

  • a village on Norfolk’s North Sea coast
  • Revetments and groynes in the 1950s, however most of the revetments were destroyed in a storm
  • Government has since refused to protect Happisburgh as it is not cost effective
  • District council recently defended the area with 5,000 tonnes of rip rap- slowing down the rate of erosion
  • 26 homes lost to the sea so far
42
Q

How are sea levels changing?

A

as carbon dioxide levels increase, temperature increases (green house effect) and sea levels rise

This is because of Thermal expansion and the melting of glaciers

Thermal expansion- When water heats up, it expands

Melting of glaciers- Warmer weather is causing glaciers to melt. This water flows into oceans

Rising sea levels are having impacts on the UK and Bangladesh

43
Q

CASE STUDY, MEDC, impact of rising sea levels

A
  • area most under threat is south east as land if flat and at low altitudes (Norfolk)
  • London protected by Thames Barrier, however it is predicted that it will soon be inadequate with rising sea levels and will need to be replaced costing £7 billion
  • Valuable agricultural land is being lost
  • Mudflats (eg Keyhaven salt marshes) are under threat- destruction of habitats
  • Homes under threat- Holderness coast
44
Q

What is a shoreline management plan?

A

a plan regarding the long term sustainable management of our coast

45
Q

What is the integrated coastal zone?

A

A management scheme which aims to protect different areas of the coastline. A coastal zone is where there is a large variety of valuable habitats and ecosystems that need to be protected

46
Q

What is one of the most sustainable ways to manage the coast?

A

‘retreating the line’

when you punch a hole in an existing sea defence to allow land to flood naturally between heigh and low tide. (The intertidal zone- the area that is above water at low tide and under water at heigh tide

47
Q

Where is ‘retreating the line’ being tested?

A

in Essex

old embankments have been punched through

invading sea water moves slowly and deposits mud, creating mudflats and salt marshes. These absorb the wave’s energy and act as a natural buffer.

During storm surges they also store water which means less water enters the Thames Estuary helping to prevent flooding

Geography (9 decks)

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