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Geography > Coasts > Flashcards

Coasts Flashcards

Coastal landscapes, erosion and deposition, risks and management

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1
Q

Features of high-energy coastlines

A
  • Rocky, cliffs
  • Found in Atlantic-facing coasts like Cornwall or Scotland
  • Rate of erosion exceeds rate of deposition
  • Landforms: headlands, cliffs
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2
Q

Features of low-energy coastlines

A
  • Sandy/estuarine
  • Less powerful waves
  • East coast like Northumberland and Lincolnshire
  • Rate of deposition exceeds rate of erosion
  • Landforms: beaches, spits
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3
Q

Examples of hard rock

A
  • Basalt
  • Granite
  • Slate
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4
Q

Examples of soft rock

A
  • Chalk (on the harder side)
  • Clay
  • Sandstone
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5
Q

What is the littoral zone?

A

Zone between the land and the sea

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6
Q

Why is it a littoral zone instead of a coastline?

A

Tides and storms constantly change the shape

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7
Q

Short-term factors that affect the shape of a coast?

A

Waves, tides and seasonal storms

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8
Q

Long-term factors that affect the shape of a coast?

A

Erosion, sea level changes due to climate change

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9
Q

Four sections of the littoral zone?
(from land to sea)

A
  • Backshore: above the influence of the waves
  • Foreshore: inter-tidal or surf zone
  • Nearshore: breaker zone
  • Offshore: beyond the influence of the waves
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10
Q

How can coasts be classified?

A
  • Geology
  • Wave energy
  • Balance between erosion and deposition
  • Changes in sea level
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11
Q

What is coastal morphology?

A

The shape and form of coastal landscapes and their features

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12
Q

What is coastal recession?

A

Another term for coastal erosion

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13
Q

What is lithology?

A

The physical characteristics of particular rocks

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14
Q

Types of lithology?

A
  • Strata
  • Bedding planes
  • Joints
  • Folds
  • Faults
  • Dips
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15
Q

What is strata?

A

Layers of rock

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16
Q

What are bedding planes?

A

Horizontal cracks, natural breaks in the strata, caused by gaps in time during rock formation

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17
Q

What are joints?

A

Vertical cracks, fractures caused by contraction or sediment drying out

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18
Q

What are folds?

A

Formed by pressure during tectonic activity, which makes rocks buckle and crumple
(e.g. Lulworth Crumple)

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19
Q

What are faults?

A

Formed when the stress on a rock exceeds its strength, causing it to fracture. The faults then slip along fault planes.

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20
Q

What is a dip?

A

Refers to the angle at which the rock strata lie
(horizontally, vertically, dipping towards the sea, dipping inland)

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21
Q

What is a concordant coast?

A

Where bands of more and less resistant rock run parallel to the coast.

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22
Q

What is a dalmatian coast?

A

Formed as a result of rising sea levels at concordant coasts.
When valleys and ridges run parallel to each other. When the sea rose and the valleys flooded, the tops of ridges remained above the sea creating islands.

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23
Q

What is a discordant coast?

A

The geology alternates between bands of more and less resistant rock, which run at right angles to the coast

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24
Q

How do headlands affect waves?

A

Force waves to refract or bend. This increases the wave power. This leads to the steepening of cliffs and eventual arches and stacks.

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25
Q

How does a wave react in a bay?

A

Their energy is dissipated and reduced. This leads to the deposition of sediment forming a beach.

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26
Q

Example of a discordant coast

A

Dorset
Coast consists of alternating bands of Portland limestone and greensands.
Greensands erodes quicker than Portland limestone.

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27
Q

How do bedding planes affect a cliff profile?

A

Bedding planes dip inland = steeper cliff profile
Bedding planes dip towards the sea = gentler cliff profile

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28
Q

Examples of igneous rock

A

Basalt
Granite

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29
Q

How do igneous rocks form?

A

From the crystillisation of magma

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30
Q

Why are igneous rocks strong?

A

They contain crystals which increase the strength and reduce the number of weaknesses which would be exploited by physical processes

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31
Q

Difference between intrusive and extrusive igneous rocks

A

Intrusive - formed from magma inside the Earth
Extrusive - formed when magma escapes through vents on the Earth’s surface

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32
Q

Average rate of erosion for igneous rocks

A

0.1-0.5cm a year

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33
Q

Examples of sedimentary rock

A

Limestone
Sandstone
Chalk

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34
Q

How do sedimentary rocks form?

A

The build-up, compacting and hardening of sediments into layers over time by lithification

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35
Q

How does the age of sedimentary rocks affect how they erode?

A

Recently formed rocks = more susceptible to erosion and weathering and erode faster

Older rocks = More resistant to erosion therefore takes longer

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36
Q

Average rate of erosion for sedimentary rocks

A

2-6cm a year

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37
Q

Examples of metamorphic rock

A

Slate
Marble

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38
Q

How are metamorphic rocks formed?

A

A change in the structure of igneous/sedimentary rocks caused by variations in heat and pressure (process called metamorphosis)

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39
Q

How is marble formed (marble = metamorphic)

A

Limestone changing structure due to the re-crystillisation of calcite

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40
Q

How do metamorphic rocks erode?

A

They are resistant to erosion

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41
Q

2 types of plants that can grow in sand dunes

A

Xerophytes - Can withstand periods of dry weather
Halophytes - Can withstand high concentrations of salt from seawater

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42
Q

What does a sand dune need to form?

A
  • Continuous supply of sand
  • Powerful winds to transport sand
  • Obstacles to trap the sand like plants
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43
Q

Order of sand dune succession

A
  1. Embryo dunes
  2. Fore dunes
  3. Yellow dunes
  4. Grey dunes
  5. Dune slack

1-3 = mobile dunes
4-5 = fixed dunes

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44
Q

Examples of plants that typically colonise embryo and fore dunes and their features

A
  • Sea rocket
  • Sea crouch

Features:
- Long roots
- Salt tolerant

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45
Q

Example of a plant that typically colonises yellow dunes and its features

A

Marram grass

Features:
- Long roots
- Salt tolerant

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46
Q

Example of a plant that typically colonises grey dunes

A

Heathers

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47
Q

Features of destructive waves?

A
  • Cause erosional processes
  • High frequency (10-15 waves per min)
  • Steep and high
  • Circular motion causes the wave to ‘plunge’ and travel a shorter distance along the beach
  • Swash less powerful than backwash
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48
Q

Features of constructive waves?

A
  • Low frequency (6-9 waves a min)
  • Long and low
  • Form gently sloping beaches
  • Deposit material
  • Swash less powerful than backwash
  • Elliptical motion causes the wave to ‘spill’ and break out further along the beach
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49
Q

What is attrition?

A

Pieces of bedload (material carried in water) hit against each other. This causes them to break and become smaller and more rounded.

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50
Q

What is corrosion?

A

A chemical reaction between the sea water (which is a weak acid) and susceptible rocks like limestone

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51
Q

What is hydraulic power?

A

Causes the breakdown of cliffs due to the force of the water being compressed into cracks in the rock, putting pressure on them to eventually break.

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52
Q

What is abrasion?

A

Where pieces of rock are picked up by waves and hit against the bed, beach or cliff. They wear away over time.

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53
Q

How are wave-cut notches formed?

A

Destructive waves erode the base of a cliff through abrasion

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54
Q

Why does a wave-cut notch collapse?

A

Continued erosion of the wave-cut notch causes the rock above it to become less and less stable until it eventually collapses and the material is washed away

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55
Q

How is a wave-cut platform formed?

A

After multiple collapsing events leading to the cliff retreating, what is left behind is called a wave-cut platform

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56
Q

How do the erosional processes lead to the formation of coastal landforms (e.g. caves, arches)?

A
  1. Destructive waves erode weaknesses in the headlands through corrosion and hydraulic action
  2. When weaknesses in the rock widen, abrasion becomes more important
  3. Over time these processes form coastal landforms
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57
Q

How is a cave formed?

A

Erosion attacks weakness in the headland. When the crack widens into a small, hollowed out area, a cave has formed

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58
Q

What coastal landforms are caused by headland erosion?

A
  • Cave
  • Arch
  • Stack
  • Stump
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59
Q

Example of an arch

A

Durdle Door on the Dorset coast

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60
Q

How are arches created?

A

When caves are eroded through the headland, an arch is created

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61
Q

How are stacks formed?

A

When the top of an arch collapses due to gravity, a column called a stack is left behind

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62
Q

How are stumps formed?

A

Continued erosion and weathering causes the stack to breakdown, forming a stump. During high tide, stumps can become submerged. Eventually, the stump will erode and nothing will be left.

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63
Q

What is isostatic change?

A
  • Refers to the level of the land
  • During an ice age, the weight of the ice forces the land to sink
  • When the ice age is finished, the melting ice causes the land to rebound back up
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64
Q

4 factors that contribute to sea level change

A
  • Isostatic change
  • Tectonic change
  • Eustatic change
  • Climate change
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65
Q

How does tectonic change affect sea levels?

A
  • Causes land to either rise or sink at the boundaries where tectonic plates meet
  • A sudden change in the movement of a plate can lead to a rise or fall of the sea bed, causing a change in sea level
  • Earthquakes can also trigger tsunamis
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66
Q

What is eustatic change?

A

The rising and falling of sea levels caused by ice ages

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67
Q

How does eustatic change affect sea levels?

A

In ice age = water stored in the form of ice so sea levels fall

After ice age = ice melts and sea levels rise

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68
Q

What is a submergent coastline?

A

When sea levels rise and land stays the same height

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69
Q

What is an emergent coastline?

A

When sea levels fall exposing more land

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70
Q

What is a ria?

A

A flooded valley formed when sea levels rise, often creating an estuary

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71
Q

What is a fjord?

A

A flooded valley formed when a glacier erodes vertically, creating a u-shape

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72
Q

Example of a fjord?

A

Lysefjord in Norway

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73
Q

Features formed at submergent coastlines

A
  • Rias
  • Fjords
  • Dalmatian coasts
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74
Q

What are raised beaches/fossil cliffs?

A
  • Caused by isostatic rebound; following an ice age the land rebounds
  • This causes the original height of the land to increase
  • This leaves behind beaches and cliffs higher than their original position
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75
Q

Example of a raised beach/fossil cliff?

A

Fife, Scotland

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76
Q

What type of coastline causes raised beaches/fossil cliffs to form?

A

Emergent coastlines

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77
Q

How much have average sea levels increased 1901-2010

A

0.19m
(using data from the IPCC)

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78
Q

Why has climate change caused sea levels to rise?

A

The melting of glaciers and ice sheets in places like Greenland and the Arctic

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79
Q

Higher sea levels cause higher tides. Why is this bad?

A
  • Higher frequency of coastal flooding
  • Removes more material from beaches, leaving cliffs less protected
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80
Q

Evidence to show global warming

A

Between 1983 and 2012, the Northern Hemisphere experienced the warmest 30 years of the last 1,400 years

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81
Q

What gases have predominantly caused global warming?

A

Anthropogenic greenhouse gas (GHG)

82
Q

Why have the levels of greenhouse gases increased in recent centuries?

A

Industrialisation

83
Q

How will an increased number of storms (caused by climate change) influence the coast?

A
  • Creates more high energy, destructive waves
  • Increased energy of sea means more material can be transported longer distance = some areas more vulnerable to erosion
  • Frequency of storm surges increases. When combined with sea level rise, these surges will reach further inland and cause more damage.
84
Q

What is dredging?

A

The removal of sediment from the sea bed for use in construction

85
Q

How does dredging increase the rate of coastal recession?

A

Causes the depth of the ocean to increase
This increases the occurrence of destructive waves because they can maintain their energy further towards shoreline

86
Q

How does a long period of rainfall increase the rate of coastal recession?

A

Weakens rock, and in turn, leads to the mass movement of material.

87
Q

How does hard engineering disrupt sediment cells?

A

By disrupting one area of the coast, further along the coast may be starved of sediment supply, which can then result in the destruction of beaches

88
Q

Example of a place where dredging occurs

A

Dredging on the coast of California has affected the supply of sediment to the Santa Barbara littoral cell

89
Q

Why is the rate of coastal recession greater in winter than summer?

A

In the winter there is more stormy weather, which is linked with higher tides and greater wave fetch

90
Q

How can wind direction influence the rate of coastal erosion?

A

Winds control the movement of waves and a dominant wind direction causes powerful waves to attack the coastline. This happens because the wave has often travelled a long distance.

91
Q

Example of a place where wind direction has affected its rate of coastal erosion

A

The south-westerly wind directing waves across the Atlantic towards Land’s End in Cornwall

92
Q

Difference between anticyclones and depressions

A

Anticyclones = areas of high pressure
Depressions = areas of low pressure

93
Q

How does the pressure of the a weather belt affect coastal erosion?

A

High pressure belts make calmer weather, leading to less coastal erosion.
Low pressure belts cause unsettled weather conditions.

94
Q

Why does coastal recession increase during high tide?

A

Waves can reach further towards the shore

95
Q

Why is the removal of mangroves bad?

A

Mangroves help to defend against coastal erosion as their roots strengthen the soil

96
Q

Example of a place that is threatened by the removal of mangroves?

A

The Maldives

97
Q

How do mangroves protect against coastal erosion?

A

As well as strengthening the soil, the trees dissipate the wave’s energy before it reaches land

98
Q

Why do many people choose to live near dangerous coastlines?

A

Either for recreation (beautiful scenery, good nightlife, etc) or for employment

99
Q

Why is Bangladesh at risk from rising sea levels?

A

Bangladesh is very low-lying so storm surges in the Bay of Bengal will cause lots of damage

100
Q

Why has climate change increased the chances of storm surges?

A

Rising global temperatures are causing oceans to warm, triggering low-pressure systems and increased stormy weather

101
Q

Storm surge definition

A

A rising of the sea as a result of wind and atmospheric pressure changes associated with a storm

102
Q

How do sea walls work to protect the coast?

A

They are made out of hard concrete that deflects waves. They are often curved to dissipate the wave’s energy and refract it back towards the sea.

103
Q

What are the benefits and costs of sea walls?

A

Benefits:
- Long-term as concrete needs little maintenance

Costs:
- They create a strong backwash that can undercut the wall
- They are expensive to build and maintain

104
Q

What are offshore breakwaters?

A

Rocks placed in a parallel line to the shore

105
Q

What are the benefits and costs of offshore breakwaters?

A

Benefits:
- Provide calm conditions behind the breakwater so the beach can be used recreationally

Costs:
- Can cause wave patterns to change
- Expensive to install

106
Q

What is rip rap and how does it protect the coast?

A

A pile of boulders often placed in front of sea walls to dissipate the wave’s energy.

107
Q

What are the benefits and costs of rip rap?

A

Benefits:
- Long-lasting
- Relatively cheap

Costs:
- Provide a hazard for people accessing the beach
- Gaps between the rocks still allows for some erosion

108
Q

What are revetments and how do they protect the coast?

A

Angled walls placed just offshore to assist in breaking down the force of the waves to reduce their ability to erode the coastline.

109
Q

What are the benefits and costs of revetments?

A

Benefits:
- More cost-effective than a sea wall

Costs:
- Often require regular maintenance
- Can create access problems to the beach

110
Q

What are groynes and how do they protect the coast?

A

Stone or wooden fences that stick out at 90 degrees from the coast. They stop material being transported through longshore drift.

111
Q

What are the benefits and costs of groynes?

A

Benefits:
- They create wider beaches, which slows down waves and reduces their energy
- Relatively cheap

Costs:
- Beaches further down the coast get narrower (terminal groyne syndrome) so more erosion takes place

112
Q

Cost of groynes

A

£150-250 per metre

113
Q

Cost of a sea wall

A

£3,000-10,000 per metre

114
Q

Cost of rip rap

A

£1,300-6,000 per metre

115
Q

Example of groynes

A

Hornsea

116
Q

Example of revetments

A

Hornsea

117
Q

Example of a sea wall

A

Scarborough

118
Q

Example of an offshore breakwater

A

Ulrome - Skipsea

119
Q

Example of rip rap

A

Scarborough

120
Q

What does ICMZ stand for?

A

Integrated Coastal Management Zone

121
Q

Why is the ICZM method used in coastal management?

A
  • Holistic approach (considers ALL factors)
  • Considers economic, social and environmental factors
  • Careful consideration of the most effective and sustainable way to manage a coastline
122
Q

When was ICZM created?

A

1992 by world leaders at the Earth Summit

123
Q

What are the factors considered using ICZM?

A
  • The risk to buildings
  • Impact on local economy
  • Impact of coastal recession and flooding on the natural environment
124
Q

What are the benefits of ICZM?

A
  • Promotes environmental conservation
  • Promotes efficient use of resources to reduce unnecessary costs
  • Tries to reduce the potential loss to all stakeholders that rely on the coast for their livelihood.
125
Q

What is a shoreline management plan (SMP)?

A
  • Each sediment cell (there are 11 in the UK) has one
  • 4 key management approaches
  • Each coastline is carefully considered to determine which SMP is most appropriate
126
Q

4 SMP management approaches

A
  • No active intervention
  • Strategic realignment
  • Hold the existing defences
  • Advance the line
127
Q

SMP approach:
No active intervention

A

No management used along this coastline with physical processes allowed to work naturally

128
Q

SMP approach:
Strategic realignment

A

Physical processes are allowed to work naturally, with monitoring and intervention only when necessary

129
Q

SMP approach:
Hold the existing defences

A

Maintaining existing defences to make sure they continue to be effective

130
Q

SMP approach:
Advance the line

A

The construction of new engineering techniques to protect the coastline from further recession

131
Q

What is a cost-benefit analysis used to determine?

A

The economic value of a coastline and if intervention is needed to protect the surrounding land

132
Q

What is an environmental impact analysis used to determine?

A

To assess the short and long-term implications of using management strategies on the environment

133
Q

Population of Happisburgh

A

1,400

134
Q

Location of Happisburgh

A

Norfolk Coast

135
Q

Name of the group aiming to protect Happisburgh’s coastline

A

Coastal Concern Action Group (CCAG)

136
Q

How fast is Happisburgh eroding?

A

Approx 0.9m a year

137
Q

Why did the rate of erosion at Happisburgh increase in the ’90s?

A

The wooden defences began to fail

138
Q

What shoreline management plan is in place at Happisburgh?

A

No active intervention

139
Q

What are the CCAG group campaigning to change the Happisburgh shoreline management plan to?

A

Managed realignment

140
Q

What hard engineering strategy is in place at Happisburgh?

A

Rip-rap (since 2012)

141
Q

Why is the local government not installing coastal defences at Happisburgh?

A

They do not believe it is cost effective
(i.e. more money spent protecting the coast than the village is worth)

142
Q

What waves are eroding Happisburgh?

A

Destructive ones from the North Sea

143
Q

What is hydraulic action?

A

The force of the waves crashing against the cliff compress air in cracks which breaks up the rock

144
Q

What is abrasion?

A

Waves carrying beach material throw it against the cliff wearing it away

145
Q

What is longshore drift?

A

The process of sediment moving along a beach through swash and backwash

146
Q

What causes the direction of swash?

A

Prevailing wind

147
Q

What causes the direction of backwash?

A

Gravity

148
Q

What is a spit?

A

Long fingers of sand which stick out from the coastline and are slightly curved

149
Q

How is a spit formed?

A

When the coast changes direction at an estuary, longshore drift continues to deposit sand

150
Q

Where are salt marshes often found?

A

Behind spits

151
Q

Why do spits usually not meet the other side of the coast?

A

The river has energy to move the sediment

152
Q

What is a bar?

A

When a spit grows across a bay

153
Q

What is a lagoon?

A

An area of water found behind a bar

154
Q

How are beaches formed?

A

Constructive waves depositing material

155
Q

Which beach is steeper - sand or shingle?

A

Shingle = steeper
Sand = gentle slope

156
Q

What is a tombolo?

A

When a spit stretches across the mainland to join an offshore island

157
Q

What are cuspate forelands?

A

When two spits eventually meet and sediment is trapped, causing new land to form

158
Q

What are the 3 parts of a sediment cell?

A

Sources = sediment generated
Transfers = sediment moves along coast
Sinks = sediment deposited

159
Q

What is a sediment cell?

A

A closed system which describes the movement of sediment around a coast

160
Q

How many sediment cells are there in the UK?

A

11

161
Q

Sediment cell: sources

A
  • Subaerial processes
  • Erosional processes
  • Sediment from rivers
162
Q

Sediment cell: transfers

A
  • Longshore drift
  • Winds
  • Tides
163
Q

Sediment cell: sinks

A

Depositional landforms, for example:
- Spits
- Bars
- Beaches

164
Q

3 types of weathering

A
  • Biological
  • Mechanical
  • Chemical
165
Q

What is weathering?

A

The breakdown of rocks where they are

166
Q

What is biological weathering?

A

When rocks are broken down by living things

167
Q

Examples of biological weathering

A
  • Plant roots
  • Algae can release chemicals
  • Animals scrap and secrete acid on the rock
168
Q

What is mechanical weathering?

A

When rocks are broken down without their chemical composition being changed

169
Q

What is the main type of mechanical weathering?

A

Salt weathering

170
Q

What is the process of salt weathering?

A
  • Seawater gets into cracks in rocks
  • Salt crystals form when the sea water evaporates
  • Crystals expand and put pressure on the rock until it breaks
171
Q

What is chemical weathering?

A

When rocks are broken down because their chemical composition changes

172
Q

What is the main type of chemical weathering?

A

Carbonation

173
Q

What is the process of carbonation?

A
  • Takes place when it is warm and wet
  • Carbon dioxide dissolves in rain making a weak carbonic acid
  • Acidic rainwater attacks rocks which contain calcium carbonate
174
Q

2 types of sub-aerial processes

A

Weathering
Mass movement

175
Q

What is mass movement?

A

When rocks and loose material slide down slopes

176
Q

When does mass movement occur?

A

When gravity overcomes the force supporting the material

177
Q

Mass movement:
Rockfall

A

When material breaks apart due to erosion/weathering and falls down the slope

178
Q

Mass movement:
Slides

A

When material moves down the slope in a straight line

179
Q

Mass movement:
Slumps

A

When material moves down the slope with a rotation

180
Q

What causes slumps to move with a rotation?

A

A mixture of heavy rainfall and erosional processes

181
Q

When do slumps usually occur?

A

When unstable permeable rock overlays more stable impermeable rock

182
Q

How do people in developed countries suffer economically from coastal recession?

A

If their house is at risk, it can be difficult to get any insurance and/or sell the house, so they lose their house and often get no compensation

183
Q

What rail line was damaged by heavy storms in 2014?

A

South-west rail line

184
Q

How long was the south-west railway line shut for?

A

2 months

185
Q

What was the estimated economic cost from the shutting of the south-west railway line?

A

£1.2bn

186
Q

What industries were disrupted by the closure of the south-west railway line?

A

Fishing, tourism

187
Q

What developed country is at risk from rising sea levels?

A

Australia

188
Q

If sea levels continue to rise, how much $ worth of infrastructure is Australia expected to lose?

A

$216bn

189
Q

How many islands are included in the Maldives?

A

Over 1,000

190
Q

What industry does the Maldives rely on?

A

Tourism

191
Q

What developing country is at risk from rising sea levels?

A

Maldives

192
Q

How has coastal flooding affected the Maldives?

A
  • Housing lost
  • Threatens freshwater sources
  • Tourist industry declining
193
Q

What are some soft engineering techniques?

A
  • Dune stabilisation
  • Cliff re-grading
  • Beach nourishment and reprofiling
194
Q

What is dune stabilisation?

A

The creation or protection of sand dunes

195
Q

How can dunes be stabilised?

A

Nourishment or planting vegetation

196
Q

Advantages and disadvantages of dune stablisation

A

Advantages:
- Natural barrier for flooding
- Support wildlife habitats

Disadvantages:
- Only a small area protected
- Ineffective during powerful storms

197
Q

What is cliff re-grading?

A

Involves restructuring and supporting the cliff to to prevent further collapse from sub-aerial processes

198
Q

Advantages and disadvantages of cliff re-grading?

A

Advantages:
- Maintains the cliff
- Provides natural habitats for plants and wildlife

Disadvantages:
- There are risks associated as often doesn’t go to plan and cliffs end up collapsing in the process

199
Q

What is beach nourishment/reprofiling?

A

Involves moving material from the upper sections of the beach to elsewhere. It slows down waves by widening beaches.

200
Q

Advantages and disadvantages of beach nourishment?

A

Advantages:
- Maintains the beach for tourist use

Disadvantages:
- Removing material from the beach threatens creatures (e.g. corals)
- Expensive
- Must be repeated

Geography (8 decks)

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