Coastal Zone Flashcards

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1
Q

What causes waves?

A

The wind

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2
Q

What are the 2 types of waves?

A

Constructive and destructive

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3
Q

What is swash and backwash?

A

Swash is the movement of the wave towards the beach.

Backwash is the movement of the wave away from the beach.

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4
Q

What are the characteristics of constructive waves? (4)

A
  • Swash is stronger than the backwash
  • Low wave in proportion to length
  • Deposition - builds beaches
  • Most common in summer
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5
Q

What are the characteristics of destructive waves? (4)

A
  • Backwash is stronger than the swash
  • High wave in proportion to length
  • Carries rocks/sand back to sea
  • Most common in winter
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6
Q

What are the different types of weathering?

A
  • Physical weathering
    • Freeze-thaw weathering
    • Exfoliation
  • Chemical weathering
  • Biological weathering
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7
Q

Explain freeze-thaw weathering

A
  1. Water collects in cracks/holes
  2. At night the water freezes and expands
  3. This widens the cracks in the rock
  4. The ice melts and refreezes over and over again
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8
Q

Explain exfoliation

A
  1. Found where there are large temperature variations
  2. Heating and cooling of a rock causes the rock to expand and contract
  3. Eventually the outer layer flakes off
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9
Q

Explain chemical weathering

A

Rain reacts with and dissolves rocks such as limestone and chalk

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10
Q

Explain biological weathering

A

The actions of plants and animals. Plant roots grow in rocks and expanding cracks. Rabbits digging into weak rocks

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11
Q

What is mass movement?

A

Downhill movement of material under the influence of gravity

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12
Q

Give some examples of mass movement? (4)

A
  • Rockfalls
  • Mud-flows
  • Rotational slip
  • Landslide
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13
Q

What are the proceses of coastal erosion? (4)

A
  • Hydraulic action (force of the water hitting the cliffs)
  • Abrasion (waves pick up loose stones and throw them against the cliff)
  • Attrition (materials hit each other and become smaller and rounder over time)
  • Solution (certain rocks being eroded from the sea water)
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14
Q

What are the processes of coastal transport? (4)

A
  • Traction (big boulders roll)
  • Saltation (smaller pebbles bounce along sea bed)
  • Suspension (lighter particles are suspended in the water
  • Solution (chemicals are dissolved in the water)
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15
Q

What is longshore drift?

A

The movement of material down the coast by waves

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16
Q

What angle do waves hit the beach?

A

45º

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17
Q

What angle do waves move away from a beach?

A

90º - perpendicular

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18
Q

What is a headland?

A

A bit of land that juts out to sea

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19
Q

What is a bay?

A

A coastal inlet that often has a beach

20
Q

What’s the difference between concordant and disconcordant coasts?

A
21
Q

How are wave cut platforms formed?

A
  1. Waves create a notch in the bottom of a cliff
  2. The notch gets bigger (overhang) until the top of the cliff is no longer supported and it collapses
  3. This happens over and over again - the cliff retreats
  4. Where the cliff was will be a gently sloping rocky platform
22
Q

What are the characteristics of wave cut platforms?

A
  • Quite smooth due to abrasion
  • Could be rock pools
  • Can be covered in sand/shingle in summer but not in winter
23
Q

What landforms are formed at headlands?

A
  • Arch
  • Stack
  • Stump
24
Q

What landforms result from deposition?

A
  • Beaches
  • Spits
  • Bars
25
Q

What is a spit?

A

A narrow finger of sand and shingle jutting out into the sea from the land

26
Q

How are spits formed?

A
  1. Sediment is transported down the coast by longshore drift
  2. It deposits at a point where the coastline changes direction or a at a river mouth
  3. More sediment is deposited over time which builds up a spit
27
Q

What forms behind a spit?

A

Mudflats and salt marshes

28
Q

What is bar?

A

A spit but it grows fully across a bay

29
Q

Why are sea levels rising?

A
  • Global warming heats up the sea causing the water molecules to expand
  • Glaciers melting
    *
30
Q

Why do cliffs collapse?

A
  • Base of cliff is eroded by hydraulic action and abrasion, making the cliff steeper
  • Weathering weakens the rock
  • Heavy rain saturates the permeable rock making the cliff heavy
  • Eventually the cliff becomes too heavy and it collapses
31
Q

What are the hard engineering strategies for coastal management?

A
  • Groynes
  • Revetments
  • Sea walls
  • Rock armour (rip-rap)
32
Q

What are the soft engineering strategies for coastal management?

A
  • Beach nourishment
  • Dune regeneration
  • Marsh creation
33
Q

How do groynes/revetments work?

A

They stop longshore drift by trapping sediment. This builds up to make a big beach which decreases the amount of energy the waves have

34
Q

How do sea walls work?

A

A curved concrete wall is built at cliffs. It reflects waves back to the sea

35
Q

How does rock armour work?

A

Big rocks are imported and put on the base of the cliff. They absorb the waves energy

36
Q

What are the advantages/disadvantages of sea walls?

A

Advantages:

  • Effective
  • Often has a walkway

Disadvantages:

  • Up to £6 million per km
  • Unatural
  • Prevents easy beach access
37
Q

What are the advantages/disadvantages of groynes?

A

Advantages:

  • Cheap
  • Bigger beach can attract tourists
  • Useful for fishers

Disadvantages:

  • Starve beaches of sediment down the coast leading to increased erosion there
  • Ugly
38
Q

What are the advantages/disadvantages of rock armour?

A

Advantages:

  • Easy to build
  • Cheap and easy to maintain
  • Can be used for fishers

Disadvantages:

  • Expensive to transport the rocks
  • Don’t fit with local geology
  • Ugly
39
Q

How does beach nourishment work?

A

Sand and shingle is added to the beach

40
Q

How does dune regeneration work?

A

Marram grass is planted. Areas can be fenced off to keep people off newly planted grass.

41
Q

How does marsh creation work?

A

Allowing low lying coastal areas to become salt marshes. Salt marshes are the barrier

42
Q

What are the advantages/disadvantages of beach nourishment?

A

Advantages:

  • Cheap
  • Blends in with existing beach
  • Increases tourist potential

Disadvantages:

  • Needs constant maintenance unless groynes are built
43
Q

What are the advantages/disadvantages of dune regeneration?

A

Advantages:

  • Maintains a natural coastal environment that’s popular with people and wildlife
  • Cheap

Disadvantages:

  • Time consuming
  • People don’t like being prohibited from certain areas
  • Can be damaged by storms
44
Q

What are the advantages/disadvantages of marsh creation?

A

Advantages:

  • Creates a habitat for wildlife
  • Cheap

Disadvantages:

  • Land will be lost
  • Farmers/land owners will need to be compensated
45
Q

What is managed retreat?

A

Allowing areas to be flooded or cliffs to collapse in areas with little value for example poor quality grazing land

46
Q

What are the characteristics of a sand dune environment? (6)

A
  • A large area exposed between high and low tides
  • A prevailing onshore wind
  • A large supply of fine sand
  • Extremely arid (no water)
  • Large amounts of salt spray
  • Alkaline conditions