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IGCSEs > Geography 🌍 | Coasts πŸ– | > Flashcards

Geography 🌍 | Coasts πŸ– | Flashcards

1
Q

What is the swash?

A

Water that rushes up the beach when the wave breaks.

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2
Q

What is the backwash?

A

Water that runs back down the beach, back out to the sea under the force of gravity.

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3
Q

What factors affect the size of a wave?

A
  • Strength of wind
  • Distance the wave has travelled
  • How long the wind has blown for
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4
Q

What is the fetch?

A

The distance the wave has travelled

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5
Q

How is a wave formed?

A
  1. Wind blows across the sea surface
  2. Friction produces a swell
  3. Wind energy makes particles rotate in the swell, moving the wave forward.
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6
Q

Why do waves break?

A
  1. The bottom of the wave touches the bed, slowing.
  2. The wave top continues faster, the wave leaning forward
  3. The top of the wave topples
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7
Q

Which wave builds up the beach?

A

Constructive wave

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8
Q

Which wave takes sediment away from the beach?

A

Destructive wave

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9
Q

Which wave type is higher energy?

A

Destructive wave

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10
Q

Which wave type is steeper?

A

Destructive wave

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11
Q

Which wave type has a strong swash?

A

Constructive wave

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12
Q

What is abrasion in the sea?

A

When sand and shingle is hauled at the cliff face with a scraping effect.

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13
Q

What is attrition in the sea?

A

When material in the sea collides with other material, breaking to smaller pieces.

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14
Q

What is solution (erosion) in the sea?

A

When chemicals in the water erode the coastline and sea material.

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15
Q

For a bay to form, there needs to be __

A

Bands of less resistant rock alongside bands of more resistant rock, perpendicular to the sea.

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16
Q

What is the main form of erosion at bays?

A

Hydraulic action and abrasion

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17
Q

What is the headland?

A

Hard rock that sticks out from the sides of bays, sheltering it.

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18
Q

Order of the erosion of a headland.

A

Crack-cave-arch-stack-stump

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19
Q

How is a cave formed?

A
  1. A crack in the cliff is widened by hydraulic action, the headland weakening
  2. Abrasion and hydraulic action widens the crack and creates a cave.
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20
Q

How is an arch formed?

A
  1. With more erosion, an arch forms as the bay breaks through the headland
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21
Q

How is a stack formed?

A

The rock of an arch weakens, the roof falling and creating a stack.

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22
Q

How is a stump formed?

A

The stack erodes more, leaving behind a stump

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23
Q

When is a stump visible?

A

Only at low tide.

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24
Q

What is a wave-cut platform?

A

The narrow, flat rocky platform at the base of a cliff, smooth from abrasion.

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25
Q

How is a wave-cut notch formed?

A

Erosion wears the bottom of a cliff through hydraulic action.

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26
Q

How does a wave-cut platform expand?

A

The notch deepens and undercuts the cliff, eventually collapsing due to gravity. The cliff retreats.

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27
Q

What is longshore drift?

A

The movement of sediment along the coastline, helped by prevailing wind.

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28
Q

How does longshore drift move sediment?

A

The prevailing winds sweep sediment to the beach, the backwash bringing it back to the sea at right angles to the beach.

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29
Q

What is a spit?

A

A long narrow finger of land sticking out into the sea from the land. They form on coasts with longshore drift.

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30
Q

How is a spit formed?

A
  1. If the coastland bends sharply, sediment extends the headland from longshore drift.
  2. It builds up to form a finger of land.
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31
Q

How does the end of the spit curve?

A

Waves and tidal currents can cause the end of the spit to make a hook.

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32
Q

Why may a spit, found in between two headlands and a river mouth, not join the two headlands?

A

The flow of a river prevents it from joining the other headland.

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33
Q

What is found behind a spit?

A

Sheltered water behind the spit deposits mud and salt marshes are formed.

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34
Q

What is a spit known as if it joins the opposing headland?

A

A sand bar.

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35
Q

What is formed behind a sand bar?

A

A lagoon.

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36
Q

What is a beach?

A

A deposit of sand and shingle at coasts, sandy beaches found mostly in sheltered bays.

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37
Q

How does an embryo dune form?

A

A deposited obstacle has sand formed around it, creating an embryo dune.

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38
Q

How is a fore dune formed?

A

The embryo dune is developed and builds up in size.

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39
Q

How is a dune stabilized?

A

Vegetation, such as marram grass, stabilizes the dunes because of their long root hairs finding water.

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40
Q

Where is more vegetation found in sand dunes?

A

At the back, further from the sea.

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41
Q

How does salinity affect vegetation in dunes?

A

The lower salinity and rotting vegetation at the back increases fertility and vegetation.

42
Q

What is a dune slack?

A

Depressions in the sand formed by wind, sometimes with ponds inside them.

43
Q

Where are coral reefs found geographically?

A

In between the tropics of cancer and capricorn.

44
Q

What conditions are needed for coral reefs to exist?

A
  • Warm water temperature
  • High salinity
  • Clear water
  • Enough light
45
Q

What is a coral reef?

A

An underwater ecosystem full of polyps - which build calcium carbonate skeletons.

46
Q

What temperature do coral reefs grow best at?

A

Between 18-28 degrees celcius.

47
Q

Below what temperature can coral not grow?

A

Below 16 degrees celcius.

48
Q

Why are coral reefs found between the tropics?

A

There is little variation in sea temperature between the tropics due to currents.

49
Q

How does coral react to freshwater?

A

The coral dies, so when rivers flow into reefs they die.

50
Q

How does coral react to silty water?

A

It blankets the coral and restricts currents, which kills the corals.

51
Q

What depth do corals need to be at?

A

At 37m.

52
Q

What are the types of coral reefs?

A

Fringing reef, barrier reef, atoll.

53
Q

What is a fringing reef?

A

A coral platform that grows out to the sea attached to the mainland. A narrow, shallow lagoon lies on top.

54
Q

What is a barrier reef?

A

A reef formed at a shallower area away from the mainland, water between too deep for coral to grow. A large lagoon forms

55
Q

What is an atoll?

A

A reef that develops around islands, circles attached to the mainland. A rise in sea level makes them grow upwards to light. A circular lagoon forms.

56
Q

What is a mangrove swamp?

A

A vegetated area found along sheltered tropical coastlines and estuaries. The mangroves can withstand salt.

57
Q

What is a halophytes?

A

Something that needs to live in salty water.

58
Q

What temperature do mangrove swamps need to be at?

A

Remain over 20 degrees celcius, with little variation.

59
Q

What conditions do mangrove swamps need?

A
  • Calm waters
  • Hot temperature
  • Salty water
60
Q

What seasonal temperature range are mangrove swamps restricted to?

A

5 degrees celcius,

61
Q

How do mangroves protect coastlines?

A

They act as a natural barrier and flood defence.

62
Q

How do mangrove swamps protect coral reefs?

A

They filter pollutants and sediment from reaching coral reefs.

63
Q

Geographically, where are mangrove swamps found?

A

Between the tropics (32N-38S), lining coasts.

64
Q

Why are mangrove swamps being cleared?

A
  • They take up thousands of acres of land, usable for agriculture
  • The shrimp agriculture industry clears them for shrimp ponds.
  • Tourists pollute
  • Urbanization
  • High quality charcoal is found.
65
Q

How are mangrove swamps turned into shrimp ponds?

A

Channels are dug into the swamp to supply freshwater and seawater, disrupting salinity.

66
Q

How can we protect mangroves?

A
  • Afforestation
  • Limiting urbanization
  • Creating govt. regulations.
67
Q

For what reasons do we protect coasts?

A
  • There are often high-income settlements along coastlines (TLDR, money.)
  • They are economically valuable for tourism (TLDR, money.)
  • Some coastal land is very valuable (TLDR, money.)
  • Protecting ecosystems (Which we rarely do, because no money)
68
Q

What coastal land are we more likely to protect?

A

Economically valuable land; we are less likely to protect land with few residents or low income farmland.

69
Q

What are the coastal hard engineering strategies?

A
  • Groynes
  • Sea walls
  • Rock armor
  • Gabions
  • Revetments
  • Offshore breakwaters
70
Q

What are groynes?

A

Wooden barriers at right angles to the beach to trap sediment and prevent it from being moved by longshore drift.

71
Q

What are the advantages of groynes?

A
  • Builds up beach, encouraging tourism
  • Traps sediment being carried by longshore drift
72
Q

What are the disadvantages of groynes?

A
  • Starves beaches further down coastline, increasing erosion there.
  • Unattractive
73
Q

What are sea walls?

A

Concrete walls placed at the base of a cliff to prevent erosion, curved to reflect energy back into the sea.

74
Q

What are the advantages of sea walls?

A
  • Effective at protecting the base of a cliff
  • Can create promenades for walking
  • Most effective
75
Q

What are the disadvantages of a sea wall?

A
  • Powerful waves will erode it over times
  • They are expensive
  • A sea wall could actually increase erosion as the reflection of energy creates a strong backwash, erosion taking place under the wall.
76
Q

What is the cost of a sea wall?

A

Β£2000 per meter.

77
Q

What is rock armor?

A

Large boulders placed at the base of a cliff to absorb wave energy.

78
Q

What are the advantages of rock armor?

A
  • Cheap and easy to maintain
  • Can be used for fishing
  • Less manmade looking than other strategies
79
Q

What are the disadvantages of rock armor?

A
  • Very difficult and expensive to transport
  • Looks different to local geology as rocks are imported.
80
Q

What are gabions?

A

Metal cages that enclose rocks and boulders to absorb wave energy.

81
Q

What are the advantages of gabions?

A
  • Cheap
  • Absorbs wave energy
82
Q

How expensive are gabions?

A

Β£100 per meter.

83
Q

What are the disadvantages of gabions?

A
  • Short lifespan
  • Unattractive and unnatural cages
84
Q

What are revetments?

A

Wood or concrete-slated barriers at the top of beaches to protect the base of cliffs.

85
Q

What are the advantages of revetments?

A
  • Cheaper than other methods
  • Less visual impact
86
Q

What are the disadvantages of revetments?

A
  • Ineffective for higher energy waves.
87
Q

What are offshore breakwaters?

A

Large concrete blocks and boulders offshore, reducing wave power or changing direction.

88
Q

What are the advantages of offshore breakwaters?

A

Retains appearance of beaches and cliffs

89
Q

What are the disadvantages of offshore breakwaters

A
  • Unattractive in the sea
  • Not very effective for high energy waves.
90
Q

What are the coastal soft engineering strategies?

A
  • Beach nourishment
  • Dune nourishment
  • Managed retreat
91
Q

What is beach nourishment?

A

Replacing beach material carried away by pumping sand often offshore, onto the beach.

92
Q

What are the advantages of beach nourishment?

A
  • Blends in with the beach
  • Can increase the size of the beach which appeals to tourists
93
Q

What are the disadvantages of beach nourishment?

A
  • Constant replacing of sand
  • Sand has to be brought in from elsewhere
  • Dredging affects natural environment
  • Costly
94
Q

What is dune nourishment?

A

Placing marram grass on sand dunes for stabilisation

95
Q

What are the advantages of dune nourishment?

A
  • Cheap
  • Natural-looking coastline
96
Q

What are the disadvantages of dune nourishment?

A
  • Damaged by storm waves
  • Areas must be zoned off to the public
97
Q

What is dune fencing?

A

Fences placed around a dune to reduce wind speed and encourage foredune deposition.

98
Q

What is managed retreat?

A

Areas of low-lying coasts are allowed to flood and erode, that sediment being deposited into the beach. Mostly in low-value areas.

99
Q

What are the advantages of managed retreat?

A
  • Costless
  • Creates salt marshes and provides wildlife habitats
100
Q

What are the disadvantages of managed retreat?

A
  • Land reclaimed by the sea is lost
  • Landowners must be compensated Β£5-10k per hectare

IGCSEs (68 decks)

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