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Geography (Physical) > Coasts > Flashcards

Coasts Flashcards

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1
Q

Describe how waves form in 5 main steps

A
  1. The wind blows over the sea, this creates ripples
  2. These ripples become bigger swells
  3. The swells approach land and the sea becomes shalower, causing the wave to slow due to friction.
  4. The top of the wave will continue at the same speed, forming a crest.
  5. The crest will eventually topple, forming a breaking wave.
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2
Q

Define the terms ‘swash’ and ‘backwash’

A

Swash is the movement of a wave up the beach.

Backwash is the movement of a wave back down the beach.

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3
Q

What is ‘fetch’?

A

The distance the wind blows over the sea, a bigger fetch will create a bigger wave.

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4
Q

List five features of a destructive wave

A
  • Created by a large fetch
  • Taller, stronger waves with lots of energy
  • They erode the coastline
  • The backwash is stronger than the swash
  • Breaks downwards with great force
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5
Q

What are the five main features of a constructive wave?

A
  • Created by a short fetch
  • Low gentle waves, in proportion to length
  • Low energy
  • Deposit sediment
  • Strong swash, weak backwash
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6
Q

What is erosion?

A

The wearing away of rock by moving forces, usually occus at the base of cliffs.

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7
Q

What is weathering?

A

Weathering is the wearing down of rock ‘in situ’ by its environment, sub ariel forces act on cliffs to break them down.

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8
Q

What is mass movement?

A

The movement of rock downhill under the force of gravity (eg. when cliffs are weakened by weatheing, pieces of rock are loosened and they fall off)

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9
Q

Define the term ‘chemical weathering’ and give an example

A

Chemical weathering is when a rock’s mineral composition is changed, leading to the disintegration of the rock

eg. Limestone is affected by slightly acidic rainwater, which contains CO2 and consequentely forms carbonic acid (in which, calcium carbonate/limestone dissolves).

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10
Q

What is mechanical weathering?

A

The physical break down of rock, which occurs without any change in the minerals in the rock

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11
Q

Freeze thaw is a type of mechanical weathering that happens in cold climates. Outline this process in 4 main steps.

A
  1. Water fills a crack or joint in the rock
  2. Water freezes so the crack is widened
  3. Repeated free-thaw action increases the size of the crack until a section of rock breaks off
  4. Loose pieces of rock are called scree
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12
Q

Describe the mechanical weathering process of exfoliation

A

In hot climates, the outer layers of rock heat up faster than the inner layers. Expansion creates cracks parallel to the surface, repeated healing and cooling stresses the rock until the top layer peels off.

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13
Q

What is biological weathering?

A

The process whereby plants and animals contribute to mechanical weathering, such as when roots widen cracks or burrowing animals help break down small pieces of rock. Organic acids released by vegetation speed up chemical weathering.

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14
Q

Define hydraulic action in the context of coastal erosion

A

Hydraulic action is the sheer weight and impact of water against the coastline (greatest under storm conditions). Air trapped in cracks and caves are suddenly compressed, increasing pressure on the rock.

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15
Q

When does abrasion occur on the coastline?

A

When breaking waves throw sand and pebbles against the rock face, breaking off pieces of rock and undercutting it. (In large storms boulders might be flung against the cliff face)

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16
Q

What is attrition (in the context of the coastal zone)?

A

Attrition is when particles carries by waves are reduced in size as they collide with cliff faces and one another.

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17
Q

What is solution?

A

Chemical erosion of rocks by sea water (most effective on limestone, which is dissolved)

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18
Q

List the 5 processes of marine transportation

A
  1. Longshore drift
  2. Traction
  3. Saltation
  4. Suspension
  5. Solution
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19
Q

Outline longshore drift in 3 mainsteps

A
  1. Swash approaches the coast in the direction of the prevailing wind
  2. Backwash travels back down the beach at 90 degrees (due to gravity)
  3. Sediment is moved along the beach in a zig zag formation known as kongshore drift.
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20
Q

Briefly explain the processes of solution and suspension

A
  • Solution is when minerals are dissolved in water and carries along in solution
  • Suspension is fine, light material that is carried along in the water
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21
Q

Outline the processes of saltation and traction

A
  • Saltation is when small pebbles and stones are bounced along the river bed
  • Traction is when large boulders and rocks are rolled along the river bed
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22
Q

What is deposition (of the sea)?

A

Deposition is when sediment is washed into a certain place by the sea and occurs when waves are low energy, often when they enter a sheltered part of the coastline (like a bay).

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23
Q

What is a headland? And what is a bay?

A

A headland is an area of hard rock (eg.limestone) protruding from the coastline

A bay is an area of soft rock (eg. clay) that is shaped as an inlet/embayment on the coast.

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24
Q

Describe the process whereby headlands and bays are created

A

Whilst soft rock will be eroded more quickly, hard rock has greater resistance and will therefore remain protruding from the coastline, whilst softer rock is eroded back into the land (by hydraulic action and abrasion).

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25
Q

Outline how wave cut notches and wave cut platforms are created

A
  • Maximum erosion occurs between the highest and lowest water marks on a cliff, because this is the area which is continually battered by waves. A wave cut notch will be created between the two marks and a wave cut platform will appear on the sea bed.
  • Because notches occur when erosion undercuts a cliff, the rock above them will weaken and eventually drop off, causing the cliff to retreat.
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26
Q

Describe the formation of a spit in 4 main stages

A
  1. Longshore drift transports sediment down the coast, in the direction of the prevailing wind
  2. A change in the shape of the land (creates by an estuary) means that longshore drift begins to deposit sediment away from the coast.
  3. A long tongue of sediment, known as a spit, will form. The end will be curved by a secondary wind.
  4. Salt marsh develops in the sheltered area behind the spit.
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27
Q

How are bars created?

A

Bars form when a spit gros across two headlands, enclosing an area of water known as a lagoon. The lagoon will eventually evaporate/be filled in by sediment.

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28
Q

What is a tombolo?

A

A tombolo is a spit that stretches away from a headland and links it to an offshore island.

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29
Q

How does global warming contribute to rising sea levels?

A

As temperature rises, the sea absorbs heat from the atmosphere and thermal expansion will occur.

30
Q

What is post glacial rebound doing to England?

A

As the North of England rises, the south is sinking - making it more susceptible to coastal erosion and flooding caused by rising sea levels.

31
Q

Where is Tuvalu and what is it’s population?

A

Tuvalu is a group of Polynesian Islands located in the pacific ocean, it has a total land area of 10 square miles and a population of around 12,000.

32
Q

Describe the three main environmental threats to Tuvalu

A
  1. Groundwater flooding - the thin coral soils that the islands are built on are porous, meaning salty sea water can arise through the land.
  2. Storm surges
  3. The king tides are getting higher by around 5mm per year.
33
Q

Name three ways salt-water intrusion is impacting on life in Tuvalu

A
  1. It kills coconut palms (the nation’s chief export is dried coconut meat)
  2. Salt water has seeped into pulaka pits, jeopardising the crops which make up much of the country’s diet. Fruit trees are also suffering. Communal crop gardens on six of Tuvalu’s 8 islands have been affected.
  3. Groundwater is becoming increasingly undrinkable.
34
Q

List some environmental impacts of rising sea levels in Tuvalu (5 in total)

A
  • Several months of the year, planes have difficulty landing because the airport’s runway is partly underwater.
  • Family burial plots are sinking into the ocean
  • Encroachment from the sea has claimed at least 1% of the countries 10 square miles
  • Flooding and storms erode soil so that it supports less plants and animals
  • Warmer temperatures bleach and kill coral.
35
Q

List 5 social impacts of rising sea levels in Tuvalu

A
  • Some Tuvalu residents have been forced to leave their homes (4,000 now live in New Zealand)
  • Families are being ripped apart
  • Cultures and traditions are dying out as residents are forced to emigrate to New Zealand.
  • Health issues (eg. stress/water borne diseases) are more common
  • New houses must be built on 10-foot-tall stilts.
36
Q

What are the three main economic impacts of rising sea levels in Tuvalu?

A
  • Tuvalu’s two main industries are suffering (fishing, agriculture)
  • Cash crops like pulaka are being killed by contaminated groundwater.
  • There has been a consistent downturn in GDP since 2002.
37
Q

Give the four political impacts of rising sea levels in Tuvalu

A
  • The government has to plan the evacuation of residents, although they are reluctant to do so.
  • The government is campaigning for the international community to take responsibility for global warming.
  • Tuvalu now relies on some aid from New Zealand.
  • In 2014, the prime minister of Tuvalu established the National Advisory Council on Climate Change.
38
Q

What are the 6 main responses to rising sea levels threatening the islands of Tuvalu?

A
  • In 2000, the country joined the UN to voice their anguish.
  • They attended the Copenhagen summit in 2009 and their chief negotiator told the rest of the world that “it looks like we are being offered 30 pieces of silver to betray our people and our future”
  • In 2013, the Prime Minister said that relocating residents should never be an option because it is “self defeating”.
  • New Zealand has offered to accept more Tuvaluans, although capping immigration to 75 people per year.
  • Residents have either abandoned threatened areas, retreated to higher ground or built homes on stilts.
  • The island of Male built a floodwall around the capital, costing around $4,000 per meter (largely funded by Japan).
39
Q

Where is the Holderness coast and why is it significant?

A

It is on the North Yorkshire coast and is the fastest eroding coastline in Europe.

40
Q

What is the current rate of erosion along the Holderness coast and how much land has been lost since Roman times?

A

The rate of erosion currently stands at 2 metres per year. A 4km strip of land has been lost since Roman times.

41
Q

Why is the Holderness coast so susceptible to erosion?

A

Much of it is made up of boulder clay (or till), which was left after the retreat of the Devension ice sheets 12,000 years ago. These soft, recent deposits sit on a platform of chalk which slopes away to the East.

42
Q

Which aerial processes cause erosion on the Holderness coast?

A
  • The boulder clay becomes saturated with rain water, causing chemical weathering in the summer and freeze thaw in the winter.
  • Cliffs fail and mass movement occurs (either as landslide or mudflow)
43
Q

List some marine processes which impact on the Holderness coast

A
  • Larrge destructive waves, hydraulic action and abrasion create wave cut notches.
  • The cliffs retreat and sediment is moved by longshore drift to the south.
44
Q

What does SMP stand for?

A

Shoreline management plan

45
Q

In what year was an SMP introduced on the Holderness coast and how much did it cost?

A

1991, £2million

46
Q

Which two strategies were employed as part of the SMP on the Holderness coast?

A
  • Rock armour along the base of cliffs
  • Two rock groynes were built to prevent longshore drift
47
Q

What issue was caused as a result of the groynes being put in place on the Holderness coast?

A

On the south, the rate of erosion increased significantly because the material that was being carried away by longshore drift was not replces, this is known as terminal groyne syndrome.

48
Q

Social impacts of coastal erosion in Albrough/Mappleton on the Holderness coast?

A
  • Stress/anxiety
  • Residents forced to relocate
49
Q

List 3 economic effects of coastal erosion on the Holderness Coast

A
  • Insurance companies refused to cover costs of coastal erosion
  • Livestock unsafe
  • Financial ruin/impacts on business
50
Q

Give 2 environmental impacts of coastal erosion in Albrough/Mappleton

A
  • Cracks/ cliffs falling, taking homes with it
  • Loss of land (9metres per year)
51
Q

Which 3 hard engineering strategies can be employed to manage coastal erosion?

A
  • Sea walls
  • Groynes
  • Rock armour
52
Q

List four soft engineering strategies used to reduce coastal erosion

A
  • Beach nourishment
  • Marsh creation
  • Dune regeneration
  • Managed retreat
53
Q

Where is Lyme Regis and what does the area suffer from?

A

Lyme Regis is located on the Jurassic Coast, West Dorset. The coastline there suffers from heavy landslides and coastal erosion.

54
Q

How much money has been spent on coastal protection in Lyme Regis in recent years?

A

£21million

55
Q

Why is the Lyme Regis coast vulnerable?

A

From below: Lyme Regis suffers from wave attack (strong westerly winds bring destructive waves)

From above: Lanslides are a major hazard (due to the geology). Chemical weathering and rock falls are common.

56
Q

Describe how the geology of the area causes landslides on the Lyme Regis coast

A
  • The coast is formed by top soil, on top of limestone, on top of Black Ven Marl
  • When heavy rainfall occurs, the porous limestones allows water to pass through.
  • Impermeable Black Ven Marl means water can sink into the ground no further.
  • This causes the top soil to destabilise and slide down the land.
57
Q

Why is the Lyme Regis coast so vulnerable?

A

It suffers from wave attack - strong westerly winds bring powerful destructive waves. Chemical weathering and rock falls are common.

58
Q

Which 4 hard engineering beach works methods have been used in Lyme Regis’ Shoreline Management plan?

A
  • Sea wall strengthened
  • Rock armour installed
  • The Cobb (a breakwater) extended with rock armour
  • 2 stone groynes to maintain sediment in front of the sea wall
59
Q

Which 3 hard engineering strategies (from above) methods have been used in Lyme Regis’ Shoreline Management plan?

A
  • Drainage improvements to encourage water to soak away
  • Metal piling to secure limestone to Black Ven Marl
  • Soil nailing to attach top soil to limestone underneath
60
Q

Which two soft engineering methods are in effect in Lyme Regis’ Shoreline Management plan?

A
  • Beach nourishment
  • Landslide early warning system installed
61
Q

Give 6 costs to Lyme Regis’ Shoreline Management plan

A
  1. Cost £21million
  2. Substantial disruption to environmentally sensitive area
  3. Temporary eye sore - piling and nailing meant Longmore Gardnes had to be ripped up
  4. Heavy maintenance burden
  5. Intensive changes to cliff habitats and processes (eg. breakwater and groynes alter currents)
  6. Terminal groyne syndrome.
62
Q

List 6 benefits to the Lyme Regis Shoreline Management plan

A
  • Safeguards 140 properties and businesses
  • Secures income from tourists (worth £994million a year to Dorset)
  • Safeguards beach
  • Improvements in amenities - beach huts and arcade installed
  • Access to sea front improved (promenade and Cobb road)
  • Landslide early warning system reassures residents
63
Q

What is a salt marsh?

A

A salt marsh is a periodically flooded, low-lying coastal wetland that is often rich in plants, birds and animals.

64
Q

Outline how salt marshes develop in 4 main steps

A
  1. They begin life as an accumulation of mud, sand and silt.
  2. Deposition builds up sediment in sheltered parts of the coastline (eg. behind a spot/bar)
  3. Salt-tolerant plants like cordgrass colonise the area (cordgrass is known as a pioneer species)
  4. Over time, more species move in to the area and causes the amount of vegetation/species in the area to grow.
65
Q

What is succession? Outline the process

A

Succession is a sequence of vegetative species that develop within an environment. Over time, vegetation will develop from small, tough plants to large complex shrubs and trees.

  • A pioneer species (hard and resistant) will colonise an area). For example, cordgrass can survive with little soil, salty water and few nutrients.
  • Pioneer species create more favourable conditions eg. Cordgrass taps mud and sand in its roots, helping to build up soil and nutrients.
  • As conditions improve, more species move in to the area.
66
Q

What types of plants will develop in salt marsh succession after cordgrass?

A

Cordgrass ⇒ Sea Lavender ⇒ Oak trees/shrubs

67
Q

Where are the Keyhaven Marshes?

A

Behind Hurst Castle Spit in South Hampshire

68
Q

How has Hurst Castle Spit been formed and how long is it?

A

The spit has been maintained by a supply of shingle from the west, carried by an easterly longshore drift.

The spit extends some 4 kilometres and provides a sheltered environment in which the mud flats and marshes have formed.

69
Q

When were the Keyhaven Salt Marshes first colonised by Spartina (cordgrass) and what did this enable?

A

First colonised in the 19th century, allowed the marshes to grow some 2metres higher than they would have done without the species.

70
Q

Why are the Keyhaven Marshes under threat from rapid erosion?

A
  1. There has been a loss of shingle/sediment supplied by longshore drift (due to the installation of two groynes and other engineering works)
  2. An increase in local sea levels
  3. More storm events
  4. Spartina species has been in decline since the 1950s (unknown cause) - without roots, sediment not binded together as well
71
Q

Why would the erosion of the Keyhaven Marshes increase risk of flooding?

A

The marshes act as a natural buffer to the sea, they absorb wave energy and protect a large area of the Hampshire coatstline, if they were lost the coast line would become exposed to wave attack and flooding.

72
Q

What measures have been put in place by the local council to protect the Keyhaven Marshes? (There are 9 in total)

A
  1. 550 metres of rock armour
  2. An armoured breakwater was built
  3. The spit was nourished with 300,000 metres of shingle
  4. A 100 metre rock revetment was built at the eastern end (to protect the spit)
  5. All footpaths are clearly marked and built above the marshes on wooden ramps(to prevent erosion)
  6. Bins have been installed
  7. Strict no entry policy at nesting times
  8. Dogs must be kept on leads
  9. Sheep allowed to graze there to keep the grass healthier

Geography (Physical) (3 decks)

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