Coasts Flashcards

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1
Q

What is the definition of ‘coast’?

A

A dynamic, ever-changing zone where the land meets the sea.

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2
Q

What is the definition of ‘wave’?

A

A movement of energy through the water caused by wind.

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3
Q

What is the definition of ‘swash’?

A

Wave movement up a beach at an angle.

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4
Q

What is the definition of ‘backwash’?

A

Wave movement down the beach. It will be perpendicular to the beach due to gravity.

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5
Q

What is the definition of ‘constructive wave’?

A

A wave with a greater swash than backwash. Therefore, it deposits more sediment than it takes away.

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6
Q

What is the definition of ‘destructive wave’?

A

A wave with a weaker swash than backwash. Therefore, it takes more sediment away than it deposits.

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7
Q

What is the definition of ‘sediment’? what are some examples?

A

Materials that can be moved and deposited elsewhere.
Sand
Rocks
Pebbles

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8
Q

What is the definition of ‘fetch’?

A

Length of open sea that the wind has blown over.

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9
Q

What is the definition of ‘longshore drift’?

A

The movement of sediment along the coast at an obtuse angle.

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10
Q

What is the definition of ‘erosion’?

A

The movement of sediment.

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11
Q

What is the definition of ‘deposition’?

A

The putting down of sediment.

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12
Q

What is the definition of ‘erosional landforms’?

A

Coastal features that are a consequence of erosion.

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13
Q

What is the definition of ‘cliff’?

A

A very steep or vertical slope.

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14
Q

What is the definition of ‘headland’?

A

Land, made of hard rock, that protrudes into the sea. It is harder to erode.

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15
Q

What is the definition of ‘bay’?

A

Soft rock between headlands will wear away more quickly, creating a coastal indent.

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16
Q

What is the definition of ‘wave-cut notch’?

A

An overhang on the cliff base, caused by the erosion of the cliff.

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17
Q

What is the definition of ‘sea cave’?

A

A deep hole in a cliff, caused by hydraulic action and abrasion.

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18
Q

What is the definition of ‘arch’?

A

A cave where the back has eroded to create a headland hole.

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19
Q

What is the definition of ‘stack’?

A

Free standing rock pillar where an arch top has collapsed.

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20
Q

What is the definition of ‘stump’?

A

Remains of a stack’s base.

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21
Q

What is the definition of ‘wave-cut platform’?

A

Flat rock surface at coast caused by erosion causing a cliff to retreat, but leaving the part underwater intact.

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22
Q

What is the definition of ‘depositional landforms’?

A

Coastal features caused by sedimentary deposition.

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23
Q

What is the definition of ‘beach’?

A

An accumulation of sediment at the coast. Often in a sheltered area (e.g. a bay).

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24
Q

What is the definition of ‘hard coastal engineering’?

A

Artificial structures to prevent erosion.

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25
Q

What is the definition of ‘soft coastal engineering’?

A

Working with nature to prevent erosion.

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26
Q

What is the definition of ‘sea wall’? what kind of coastal engineering is it?

A

Structures made out of concrete or similar in order to stop coastal erosion. It helps to break waves early + prevent flooding in heavy storms.
Hard.

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27
Q

What is the definition of ‘rock armour’? what kind of coastal engineering is it?

A

Or rip-rap. Large boulders placed to prevent erosion.

Hard.

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28
Q

What is the definition of ‘reef’? what kind of coastal engineering is it?

A

Rocky revetments.

Hard.

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29
Q

What is the definition of ‘groynes’? what kind of coastal engineering is it?

A

Barriers made out of wood/rock/similar placed perpendicular to the beach in order to stop longshore drift moving too far.
Hard.

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30
Q

What is the definition of ‘revetments’? what kind of coastal engineering is it?

A

Barriers made out of wood/rock (which are called reefs)/similar placed parallel to the beach to cause waves to break earlier.
Hard.

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31
Q

What is the definition of ‘beach replenishment’? what kind of coastal engineering is it?

A

Adding sand/pebbles to a beach to widen said beach + prevent erosion.
Soft.

32
Q

What is the definition of ‘dune regeneration’? what kind of coastal engineering is it?

A

The development and/or maintenance of dunes to help accumulate sediment + widen beach.
Soft.

33
Q

What is the definition of ‘managed retreat’? what kind of coastal engineering is it?

A

Planned removal of human habitation to allow natural erosion.
Soft.

34
Q

What causes waves?

A

An energy transfer over the sea surface as the wind blows.

35
Q

Which factors determine wave size? how many are there?

A

Wind strength.
Wind duration.
Fetch.

36
Q

Why do waves break?

A

They break through friction. As it gets shallower, the bottom begins to go more slowly but the top continues at the same speed. Friction opposes motion; therefore, the wave will break.

37
Q

What is the prevailing wind in the British Isles?

A

The southwesterly wind.

38
Q

How many parts are there to a wave? what are they? how do they work?

A

Two: the swash and the backwash.
The swash moves at an angle up the beach.
The backwash moves straight back down due to gravity’s effect.

39
Q

What will a wave do to sediment?

A

It will either deposit or remove sediment, which is known as longshore drift.

40
Q

What are some features of a constructive wave?

A
The swash is greater than the backwash.
Low + flat.
More common in calm weather.
Low energy.
Low frequency (6-8 per minute).
Far apart.
Deposit more material than they take away.
NI has more constructive than destructive waves.
Gentle slopes are formed.
41
Q

What are some features of a destructive wave?

A
The backwash is greater than the swash.
High + steep.
More common in winter.
High energy.
High frequency (10-15 minutes).
Close together.
Take away more sediment than they deposit.
Steep slopes.
42
Q

What are the four kinds of erosion?

A

Hydraulic action.
Abrasion (corrasion).
Attrition.
Solution (corrosion).

43
Q

What is hydraulic action?

A

The weight of water upon compressed air inside a crack will impact the crack, causing it to break up + become bigger. It will also cause it to move rocks.

44
Q

What is abrasion?

A

Or corrasion. Sediment is waves is ‘hurled’ at the rock, scraping + gouging it.

45
Q

What is attrition?

A

Loose fragments of sediment (e.g. pebbles) knock into each other, which erodes them. It rounds them and makes them smaller.

46
Q

What is solution?

A

Saline water reacts with sediment fragments (e.g. pebbles) to create salt and water (neutralisation).

47
Q

What direction does longshore drift always go?

A

Right/east.

48
Q

What factors will make rock easier to erode?

A

Sedimentary rock.

Weathered rock — worn away by weather + plants.

49
Q

Where will sediment be deposited by longshore drift?

A

Waves lose energy in sheltered areas; therefore, eroded sediment will be deposited there.

50
Q

Why do beaches form in bays? why are they beneficial?

A

Waves lose energy and deposit sediment in sheltered areas e.g. bays. They are beneficial to bays as they act as buffers; nevertheless, waves in bays have little energy, as aforementioned.

51
Q

How are wave-cut platforms and notches formed?

A

Headlands must take the full force of waves after the soft rock is eroded.
Waves erode (hydraulic action + abrasion) lower part of cliff, forming a wave-cut notch.
The rock above will collapse and be eroded in the sea.
The process continues repeating further and further in, but a wave-cut platform is left underneath the sea.

52
Q

What is the process of forming a cave, an arch, a stack and a stump?

A

Processes of hydraulic action and abrasion.
Hydraulic action acts on cracks, making them wider and deeper — beginning of a cave.
Eventually, a cave forms — cave.
The rock erodes the back of the cave — arch.
The top collapses due to pressure + lack of support — stack.
Stack will erode due to hydraulic action + abrasion — stump.
Stump will erode, leaving little trace that it was ever there.

53
Q

What is a shingle?

A

A pebble-ridden beach.

Shingle can also mean ‘many pebbles’.

54
Q

How are spits formed?

A

Constructive waves causing longshore drift to continue into the sea + deposit material.

55
Q

How are hooks formed?

A

Strong winds curving the end of a spit.

56
Q

How are bars formed?

A

A spit joining two headlands together.

57
Q

How are tombolos formed?

A

A spit joining an island.

58
Q

What are some advantages of sea walls?

A

Long-lasting.

Prevent loss of revenue/lives.

59
Q

What are some advantages of rock armour?

A
Or rip-rap.
Relatively cheap (£2.5k per metre).
More natural-seeming — does not decrease tourism.
60
Q

What are some advantages of groynes?

A

Effective at stopping longshore drift.
Last 15-20 years.

61
Q

What are some advantages of revetments/reefs?

A

Waves erode them instead of cliffs.

Waves break earlier.

62
Q

What are some advantages of beach nourishment?

A

It helps to build up a beach that can protect cliffs

It fits in

63
Q

What are some advantages of managed retreat?

A

It is relatively cheap in the long term.

Salt marshes are diverse + home to many important species.

64
Q

What are some disadvantages of sea walls?

A

Expensive (£2-5k per metre).
Can be destructive to + scour the beach if poorly designed.
Aesthetically displeasing.

65
Q

What are some disadvantages of rock armour?

A

Or rip-rap.
Short-term, as they can move.
Erosion is then focussed around the sides of the rock armour.

66
Q

What are some disadvantages of groynes?

A

Cannot be repaired — must be expensively fully replaced.
Permeable.
Disrupt the beach and are unsightly.

67
Q

What are some disadvantages of revetments/reefs?

A

Not very long-lasting.

68
Q

What are some disadvantages of beach nourishment?

A

Expensive — £1m per mile.
If taken from another beach (i.e. instead of dredging), not sustainably sourced — will destroy an ecosystem for the benefit of other.
The beach will erode more quickly as it is not tightly packed as in nature.

69
Q

What are some disadvantages of managed retreat?

A

Human land is lost to the sea.

Landowners have to be compensated — up to £5-10k per ha.

70
Q

What are some uses of the coast?

A
Homes.
Seaside resorts.
Farming.
Industry.
Fishing.
Ports.
Defence (i.e. navy).
Dredging (>1m tonnes of sand/gravel from sea bed p.a. e.g. for road building).
71
Q

Where is Happisburgh?

A

On the north Norfolk coast.

72
Q

What is happening in Happisburgh in terms of coastal erosion?

A

The coast is eroding at an enormous rate.
Livelihoods are disappearing because:
— government will not pay for defences and
— insurance does not cover ‘coastal erosion’ — houses cannot be sold (not worth anything).
— Happisburgh loses 1m p.a., but some places lose 1m per month.

73
Q

Why is Happisburgh eroding so quickly?

A

Cliffs are soft: sand + clay.
Cliffs are very weathered — rain soaks in and is held — the more rain, the weaker the cliffs.
North Sea is large; therefore, a large fetch. Winter has more destructive waves — combining these two leads to huge cliff chunks being destroyed in storms with huge waves.
There are some coastal defences — groynes: not good enough by themselves — rock armour: not enough — revetments: destroyed.

74
Q

How are saltmarshes formed?

A

Saltmarsh/mudflat can form from deposited sediment in the sheltered area behind the hook.

75
Q

How are lagoons formed?

A

They are the bays behind bars.