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Aa Hodder Geography > Coasts > Flashcards

Flashcards in Coasts Deck (492):
1

What are coastal zones

Dynamic environment a with distributive landscapes formed by the interaction of a range of wind, marine and terrestrial processes

2

How much of the worlds population live on coastal plains

About 50%, with over 59% living within 150km of the sea

3

What kind of systems are coastal environments

Open systems

4

Example of feedback in a coastal system

Increased deposition on a beach but there is no corresponding change in the amount of sediment removed from the beach, then the beach features may change and the equilibrium is upset

5

What are inputs into an open coastal system

Energy from:
Waves
Tides
Sea currents

Sediment
Geology of the coastline
Sea level change

6

Transfers in an open coastal landscape

Erosions processes
Wind and water transport

7

Components in an open coastal system

Erosional landforms and landscapes.
Depositional landforms and landscapes.

8

Outputs in an open coastal system

Dissipation of wave energy.
Accumulation of sediment above the tidal limit.
Sediment removed beyond local sediment cells.

9

Example of a negative feedback mechanism in a coastal environment

A beach in dynamic equilibrium.
Sediment is erodes from the beach during a storm.
Sediment is deposited offshore forming an offshore bar.
Waves now forced to break before reaching the beach disposing their energy and reducing further erosion when they reach the beach.
When the storm calms, normal wave conditions rework sediments from the offshore bar back to the beach.

10

What do some negative feedback mechanism act to do

Stabilise coastal morphology and maintain a dynamic equilibrium

11

What kind of landscape is a coastal landscape

Geomorphological

12

What do coastal landscapes consist of

A constantly changing assemblage or erosion and depositional landforms; they are the result of continuous change in the elements of a coastal system

13

What do the processes operating in coastal systems that continually shape the coastal landforms create

Distinctive landscape features

14

What does the coastline itself consist of

A series of different zones where specific conditions prevail that depend on factors such as tides, wave action and the depth of the sea

15

What are the 5 different zones in a coastline

Backshore
Foreshore
Inshore
Offshore
Nearshore

16

Where is the backshore

The area between the high water mark (HWM) and the landward limit of marine activity.

17

When does changes to the backshore usually take place

Only during storm activity

18

Where is the foreshore

The area lying between the HWM and the low water mark (LWM).

19

What is the most important zone for marine processes in times that are not influenced by storm activity

Foreshore

20

Where is the inshore

The area between the LWM and the point where waves cease to have any influence on the land beneath them

21

Where is offshore

The area behind the point where waves cease to impact upon the seabed and in which activity is limited to deposition of sediments

22

Where is the nearshore

The area extending seaward from the HWM to the area where waves begin to break and no longer have an effect on the land beneath them

23

What 3 zones are included in the nearshore

Swash zone.
Surf zones.
Breaker zone.

24

What is the swash zone

The area where a turbulent layer of water washes up the beach following the breaking of a wave

25

What is the surf zone

The area between the point where waves break, forming a foamy, bubbly surface, and where the waves then move up the beach as swash in the swash zone

26

What is the breakerzone

The area where waves approaching the coastline begin to break, usually where the water depth is 5 to 10m

27

What does using a systems approach help to explain in a coastal landscape

Variations and changes that occur along a coastline. It also helps us to predict the possible consequences of natural processes or proposed human interventions. This can help us to foresee positive or negative impacts and plan for them

28

What is the coastline of England and Wales divided into

Eleven sediment cells where each cell can be seen as a system in which there are clear inputs (e.g from rivers), transfers of sediment (e.g longshore drifts), stores (beaches and spits) and transfers to the deep ocean

29

If changes occur in a a sediment cell what may it lead to

Feedback, either positive or negative

30

How can cliff erosion in a sediment cell lead to negative feedback

Cliff erosion leads to slumping, the mass of scree at the bottom of the cliff will, until it's removed by wave action, protect the base of the cliff from further retreat. Here changes within the system reduces the causes of further disruption (dampening down the change)

31

What is scree

Collapsed cliff material at the base of the cliff

32

How can a spit create positive feedback

If a spit extends across a river estuary, reducing river velocity due to greater friction, this may lead to further spit growth and so yet further reduction in river velocity

33

Why are the sediment cells closed systems

Within each cell sediment is largely recycled, maintaining a state of relative balance and are, as such, closed sediment systems

34

What can coastal systems be seen operating at

Various scales

35

What will happen to a beach if inputs of sediment exceed outputs

The beach will extend in height, length and/or width

36

If we consider a single beach within its larger sediment cell, what can we observe

That if the beach experiences a positive sediment budget then somewhere else in the wider cell must be experiencing a sediment loss for the overall balance to be the same

37

By tracking the changes in the movement of sediment, what can we get a better understanding of

The connections within the system

38

While generally sediment cells are seen as closed systems, what is the reality

There is a slight loss of sediment to outputs beyond the system

39

Example of sediment being an output from a sediment cell

If wave enemy is very high or currents very strong, then sediment may be transferred to neighbouring cells, be 'lost' to deeper sea areas off-shore or be transferred to stores beyond the active coastal zone, such as upper beaches, coastal dunes and mudflats

40

What is a sediment sink

When sediment is permanently lost to the system, the destinations are known as sediment sinks

41

What do the conditions in each zone on a beach depend on

Factors such as tides, wave action and the depth of the sea

42

What are the 11 sediment cells

St Abb's head - Flamborough head
Flamborough head - the wash
The wash - river Thames
River Thames - Selsey ball
Selsey ball - Portland bill
Portland bill - lands end
Lands end - river Severn
River Severn - st David's head
St David's head - bardsey sound
Bardsey sound - great orme
Great orme - solway firth

43

What are many coastal features created by

The action of wind, waves, tides and sea currents

44

What is erosion

The wearing away of the earths surface by the action of ice, wind and water

45

What is weathering

The breakdown or decay of rock at or near the the earths surface in situ. Rock fragments will remain until they are removed by erosion processes. Weathering can be mechanical, biological or chemical

46

What is mass movement

The movement of material downhill by gravity and often assisted by rainfall

47

At the coast what is the main form of energy

Waves

48

What 3 things produce waves

Tectonic activity
Underwater landslides
Wind

49

What is wind

The movement of air from one place to another. Air moves from areas of high atmospheric pressure to areas of low atmospheric pressure. This movement is known as wind

50

What does the greater the pressure gradient between two places mean

The stronger the wind

51

What does prevailing wind mean

The most usual

52

In the UK, what is the prevailing wind direction

From the south-west

53

Before reaching our coasts, what have the prevailing winds blown over

The broad expanse of the Atlantic Ocean - this means it has blown over 3000 miles of open

54

What is the fetch

The distance which the wind blows over before reaching the coast

55

What are the 3 factors affecting wave energy

Fetch
Strength
And duration of wind

56

What leads to the formation of waves

As wind blows over the surface of the sea frictional drag leads to a transfer of energy and the formation of waves

57

How is wind an agent of erosion

As it can pick up and remove sediment (e.g sand) from the coast and then use it to erode other features

58

What is the most common type of wind erosion

Abrasion

59

Why is wind an important agent of moving sediment along the coast or further inland and beyond the shoreline

Becsuse it can pick up and move material

60

Once waves have been created by the wind, what do they become

The main agent that shapes the coastline

61

What can waves breaking at the coast do depending on their characteristics

Build up beaches or remove material

62

Why do waves break

Waves start out at sea and have a circular orbit.
As waves approach the shore friction slows the base of the wave.
This causes the orbit to become elliptical.
Until the top of the wave breaks over.

63

What are the characteristics of waves

Wave height - this is the height of the difference between a wave crest and the neighbouring trough
Wave length or amplitude - this is the distance between successive crests
Wave frequency or wave period - this is the time for one wave to travel the distance of one wave length, or the time between one fresh and the following fresh passing a fixed point

64

What is backwash

The action of water receding back down a beach towards the sea

65

What is swash

The rush of water up the beach after a wave breaks

66

What does the sea bed act as for waves

A source of friction as it is rough

67

What are constructive waves

Waves with a low wave height, but with a long wave length and low frequency of around 6-8/min. Their swash tends to be more powerful than their backwash and as a consequence beach material is built up.

68

What are destructive waves

Waves with a high wave height with a steep form and high frequency (10-14/min). Their swash is generally weaker than their backwash, so more sediment is removed than is added

69

How do constructive waves add to beach deposition

Their swash pushes more material from offshore up the beach than the backwash removed

70

Where is most of the energy in constructive waves used

In forward movement up the beach rather than flowing back down the beach and much water is lost percolation

71

As backwash is reduced in constructive waves, what happens to the following swash

It is less impeded in its movement up the beach

72

What are constructive waves associated with

A gentle beach profile, although over time they will build up the beach and make is steeper.

73

Why do constructive waves rarely reach the foot of the cliff

Because the wave energy is absorbed by the beach

74

Why do destructive waves mean beach material is easier to remove

As they crash down they loosen beach material

75

Why is the swash of destructive waves short lived

As energy has gone into a more vertical impact

76

What is the net effect of destructive waves

The removal of beach material along the shoreline

77

What does the strength of the backwash of destructive waves do

Takes material down the beach and impedes the next swash

78

What are most beaches subject to an alternating cycle of

Constructive and destructive waves e.g constructive waves build up a beech resulting in a steeper beach profile which encourages destructive waves

79

What landform is associated with constructive waves

Berms

80

What landform is associated with destructive waves

Storm berms

81

Example of negative feedback because of waves

Constructive waves operate to build up a beach, eventually the beach profile steepens which can encourage destructive waves (plunging rather than surging) which then remove material from the beach and deposit it offshore. This, in turn, can result in the beach profile becoming less steep again, encouraging constructive rather than destructive waves to form. All things being equal, this will continue until a state of dynamic equilibrium is reached

82

What happens when waves approach a coastline that is indented

They are refracted and become increasingly parallel to the coastline.

83

Around headlands, why do waves have greater energy to erode

Waves tend to break and have higher frequency, wave height and steepness, which gives them greater energy

84

How does wave refraction occur on a headland

waves approaching the headland meet shallower water first, while the part of the wave approaching the bay is still in deeper water. Friction with the sea floor slows the headland approaching waves and causes their frequency to increase.

85

In bays what leads to a constructive impact of waves

The waves spread out and become less frequent which leads to a reduction in wave energy

86

What is the overall effect of wave refraction

Wave energy becomes concentrated on the headland. It accounts for the presence of erosive features of headlands and deposition features in bays

87

In theory, how would continued erosion of the headland and deposition in the bay's result in a state of equilibrium

The shape of the coastline would remain static due to a balance between the potential erodibility of the rocks and the effects of wave refraction (in reality though conditions rarely remain stable enough for long enough for this to happen)

88

What is a current

Refers to the permanent or seasonal movement of surface water in the seas and oceans.

89

What are the three types of currents

Longshore currents (sometimes known as littoral currents)
Rip currents
Upwelling

90

Why do longshore currents occur

Because most waves approach the coastline at an angle. The result is a flow of water (current) running parallel to the shoreline. This moves water and transports sediment parallel to the shoreline

91

What are rip currents

Strong localised underwater currents that occur on some beaches and move water away from the shoreline.

92

How do rip currents form

They develop when a series of plunging waves cause a temporary build up of water at the top of the beach. Met with resistance from the breaking waves, water returning down the beach (the backwash) is forced just below the surface following troughs in the beach profile. The fast-flowing offshore surge of water can be hazardous to swimmers

93

What is upwelling

The movement of cold water from deep in the ocean towards the surface

94

How does upwelling occur

The dense cold water replaces warmer surface water and creates nutrient rich cold ocean currents. These currents form part of the pattern of global ocean circulation currents

95

What is wave refraction

When waves approach a coastline that is not regular shape, they are refracted and become increasingly parallel to the coastline. The overall effect is that wave energy becomes concentrated on the headlands, causing greater erosion. The low-energy waves spill into the bay, resulting in beach deposition

96

What is longshore or littoral drift

When waves approach the short at an angle and swash and backwash then transport material along the coast in the direction of the prevailing wind and waves

97

What are tides

What's in the water levels of seas and oceans caused by the gravitational pill (another source of energy) of the moon and, to a less extent, the sun

98

What creates a high tide

The moon pulls water towards it, creating a high tide, and there is a compensatory bulge on the other side of the earth. In areas of the world between these two bulge the tide is at its lowest

99

What are the 3 classifications of tidal range

Macrotidal - more than 4m
Mesotidal - 2-4m
Microtidal - less than 2m

100

What tides does the UK coastline experience each day

2 high tides and 2 low tides

101

What is the tidal range

The relative difference in height between low and high tides

102

What do tidal ranges determine

The upper and lower limits of erosion and deposition and the amount of time each day that the littoral zone is exposed to weathering

103

What is the tidal range affected by

The relative position of the sun and the moon

104

How are Spring tides formed

Twice in a lunar moon when the moon, sun and earth are in a straight line so the tide raising force is strongest

105

How are neap tides formed

Twice a month, the moon and sun are positioned at 90* to each other in relation to the earth. This alignment gives the lowest monthly tidal range

106

What do tidal ranges generate

Relatively prideful tidal currents which are an important source of energy

107

What are tidal currents important in

As they are particularly strong in estuaries and narrow channels, the currents are important in the transfer of sediment within the costal system or beyond (as an output)

108

When do tidal or storm surges occur

When meteorological conditions give rise to strong winds combine with high tides to produce much higher water levels than normal.

109

Example of a place tidal or storm surges occur and why

in the North Sea when intense low pressure weather systems (depressions) have the effect of rising sea levels. The sea level can rise by about 1 centimetre for every 1 millibar drop in pressure. Strong winds drive waves ahead of the storm, pushing the sea water towards the coastline. This has the effect of piling water up against the coast. The shape of the North Sea means that as sore S move south water is funnelled into a narrowing channel.

110

What intensifies the effect of storm surges

Spring tides

111

What is a high energy coast

A coastline where strong, steady prevailing winds create high energy waves and the rate of erosion is greater than the rate of deposition

112

What is a low energy coast

A coastline where wave energy is low and the rate of deposition often exceeds runs rate of erosion of sediment

113

What is a sediment cell

A distinct area of coastline seperated from other areas by well-defined boundaries, such as headlands and stretches of deep water

114

Characteristics of high energy coastlines

Consistently strong waves.
Strong, steady prevailing winds with long fetch to create high energy waves.
Rate of erosion is greater than rate of deposition.
Net transfer of material from coastline to sea.
Erosion landforms like headlands and bays found here.

115

In the UK where are high-energy coastlines found

Along stretches of the Atlantic-facing coat, such as Cornwall or North-west Scotland

116

Characteristics of low energy coastline

Waves are less powerful.
Rate of deposition is greater than the rate of erosion.
Wave energy is low.
Typical landforms include beaches and spits.
More likely to be in a state of equilibrium.

117

In the UK where are low-energy coastlines found

Lincolnshire

118

Why are low energy coastlines likely to be in a state of stable equilibrium

Because they have key inputs, transfers and outputs in balance

119

Globally, where does most sediment come from

Rivers, streams and coastal erosion, although there are local variations

120

What are 6sources of sediment

Rivers
Cliff erosion
Longshore drift
Wind
Offshore
Storm surges

121

How are rivers a source of sediment

Sediment is transported in rivers and is deposited in river mouths and estuaries where it is then reworked by waves, tides and currents. Most coastal sediment originates from rivers

122

When is cliff erosion particularly an important source of sediment

This can be particularly important along stretches of coastline where rocks are soft.

123

Example of cliff erosion being an important source of sediment

One example in the Holderness Coast where glacial fill forms unstable cliffs of Boulder clay.

124

How is longshore drift a source of sediment

Sediment is transported from one stretch of coastline (as an output) to another stretch of coastline (an an input)

125

How is wind a source of sediment

In glacial or arid regions, wind blow sand can be deposited in coastal regions. Sand dunes can act as both a sink and source of sediment (sand)

126

How is offshore a source of sediment

Sediment from offshore csn be transferred into the coastal (littoral) zone by waves, tides and currents.

127

How did the Chesil Beach in Dorset form

Sea levels rose at the end of the last glacial period, resulting in a considerable amount of coarse sediment being bulldozed onto the south coast of England.

128

What can sediment cells be divided into

Smaller sub-cells such as the cell 2 on the east coast of England, which stretches from Flamborough Head to the Wash has a sub-cell within it that stretches from Flamborough Head to the mouth of the Humber Estuary

129

What is a sediment budget

The balance between sediment being added to and removed from a sediment cell costal system

130

What leads to a positive budget or a surplus of sediment and causes the shoreline to build towards the sea

If more material is added to the sediment cell than is removed then there is a net accretion of material

131

What results in a negstive budget or deficit of sediment and causes the shoreline to retreat land wards

If more material is removed from the cell than is added

132

In principle, what does the sediment budget seek to achieve

A state of dynamic equilibrium where erosion and deposition are balanced

133

What can upset the balance of a sediment budget in dynamic equilibrium

Events such as an increase in river sediment as a result of a food. This, in turn, leads to deposition in the river estuary. A severe storm might also upset the balance by eroding a beach and transferring sediment outside the system

134

What does calculating the sediment budget for a cell require

The identification of all sediment sources and sinks and an estimation of the amount of sediment added and removed each year. Calculating the budget is extremely difficult and relies on the use of complex models and estimations

135

What are processes

The 'how' and 'why' of change in a system. They are the mechanisms that operate on the inputs and results in particular outputs.

136

What two sets of geomorphological processes are coastlines affected by

Marine processes
Sub-aerial processes

137

What are marine processes

These operate upon the coastlines that are connected with the sea, such as waves, tides and ,offshore drift

138

What are sub-aerial processes

These include processes that slowly break down the coastline, weaken the underlying rocks and allow sudden movement or erosion to happen more easily. Material is broken down in situ, remaining in or near its original position. These processes may affect the shape of the coastline, and include weathering, mass movement and run-off

139

What do all processes do to create a wide range of uniquely coastal landscapes

Interact

140

How much energy can waves generate as they break against the foot of a cliff

25-30 tonnes m^-2

141

In 2014, what happened in Dawlish

A particularly powerful storm hit Dawlish and destroyed part of the sea wall and a section of rail track cutting the rail connection between Devon and Cornwall for months. This storm altered the Devon coastline as large a,punts of sediment were swept away from beaches and sand dunes at Dawlish Warren (spit) were severely eroded.

142

How does coastal erosion play a key role in the coastal system

By removing debris from the foot of cliffs and provides an important input into coastal sediment cells

143

In reality, what do the processes of marine erosion do

Work together to erode a stretch of coastline

144

What are the 5 types of marine erosion

Hydraulic action
Wave quarrying
Abrasion
Attrition
Solution

145

What is wave quarrying

When waves break against a rock face with joints facing the wave, air inside the joints is highly compressed, creating enormous pressure within the fissure. As the water pulls back, there is an explosive effect of the air under pressure being released. The overall effect of this over time is to weaken the cliff face and storms may then remove large chunks of it.

146

What is wave quarrying sometimes known as

Cavitation

147

What is hydraulic action

The impact on rocks of the sheer force of water itself (without debris). This can exert enormous pressure upon a rock surface, weakening it and dislodging pieces.

148

What is abrasion

The material that the sea picks up also wears away rock rocks. As waves advance, they pick up sand and pebbles from the seabed. When they break at the foot of the cliff, the transported material is hurled at the base of the cliff - chipping away at the rock.

149

What is solution

Some calcium-based rocks such as chalk and limestone, is readily soluble and dissolved minerals can then be removed in solution. This process is very similar to a type of weathering called carbonation.

150

What is attrition

Whilst attrition doesnt directly alter the shape of the coastline it does result in a wearing away of rock participles. Angular rock fragments are smoothed and reduced in size forming pebbles, shingle and sand. This occurs due to friction as particles are rolled over each other by the action of waves and currents.

151

What are the 7 factors that affect the rate of coastal erosion along any stretch of coastline

Waves
Fetch
Sea depth
Shape of the coastline
Beach presence
Human activity
Geology

152

How do waves affect the rate of coastal erosion

Steeper high-energy waves have a greater erosive power than low energy waves. The point at which the wave breaks is important too. Waves that break at the foot of a cliff release more energy than those that break off-shore.

153

How does fetch affect the rate of coastal erosion

A wave that has built up over s greater distance will have generated more energy

154

How does sea depth affect the rate of coastal erosion

A steeply-shelving sea bed will create higher and steeper waves

155

How does the shape of the coastline affect the rate of coastal erosion

Headlands attract wave energy through refraction

156

How does the beach profile affect the rate of coastal erosion

Beaches absorb wave energy and provide some protection against erosion. Steep, narrow beaches are effective at dissipating energy from flatter waves. Flatter, wider beaches spread out incoming wave energy and are better at dissipating high waves. Shingle beaches absorb the impact of steel waves as well due to energy being dissipated through friction

157

How does human activity affect the rate of coastal erosion

Beach material (sand and shingle) is removed from some coastlines leading to an increase in erosion. In other areas coastal protection may reduce the rate of erosion C

158

How does geology affect the rate of coastal erosion

Perhaps the most important factor in determining the nature of the erosion all processes. It includes lithology, structure and dip

159

What is lithology

The physical strength and chemistry of rocks

160

What is structure of a coastline

The variation and arrangement of rocks along a coastline

161

How does lithology affect the rate of coastal erosion

Some rocks, like granite are very resistant to erosion whist others, such as clay are very vulnerable. Some rocks, like limestone, are well-jointed and cracked, which means that the sea can penetrate along lines or weakness, making them more vulnerable to erosion

162

Example of lithology determining erosion

Granite at lands end has been eroded by 10cm while Boulder clay at the Holderness Coast has been eroded by 120cm in the last century

163

How does structure affect the rate of coastal erosion

Along some coastlines rocks lie parallel to the coast (concordant coastline) whereas in some areas rocks lie perpendicular (discordant)

164

What is dip

Where cliffs have horizontal strata/bedding planes they may dip or slope

165

How does dip affect the rate of coastal erosion

When rocks dip inland steeper cliffs may form. Where rocks dip towards the coasts, cliffs tend to produce more gently sloping features

166

What are concordant coastlines sometimes called

Pacific e.g Dorset

167

What are discordant coastlines sometimes called

Atlantic

168

How do coves form

Along a concordant coastline, a resistant rock like limestone can protect the coastline from erosion, only allowing the sea to break through in a few places. Where the sea does break through it can more readily excavate the clay behind to form a cove e.g Lulworth Cove

169

Which coastline has examples of both concordant and discordant coastlines

The southern coast

170

What can wave and tidal energy that is not used for erosion of lost through friction be used for

Transportation

171

What does transportation represent

A significant transfer/flow of material is controlled and determined by the power of the waves

172

What does transportation of material by seawater depend on

The size and weight of the material and the energy of the transporting flow

173

What are the 4 types of transportation

Traction
Saltation
Suspension
Solution

174

What is traction

Large stones and boulders are rolled along the sea bed and beach by moving sea water. They are too heavy to be picked up and carried and will only move if energy level are high enough

175

What is saltation

Small stones bounce along the seabed and beach. This process is also associated with high energy conditions. As the particles land they may dislodge others.

176

What is suspension

Very small particles of sand and silt are carried along by the moving water, within the flow. Suspension is most likely when flow is turbulent. Large amounts of suspended load, especially near estuaries, can cause a murky appearance of the sea

177

What is solution

Dissolved materials are transported within the mass of moving water. This form of transportation plays an important role in the carbon cycle, transferring and depositing carbon in the oceans.

178

Describe the process of longshore drift

Swash transports material up the beach whilst backwash removes it back down the beach.
When the wind direction is oblique to the shore, swash rushes up the beach in the same direction as the wind, and so carries material up the beach at an angle.
The backwash then pulls material down the beach at right angles to the shore (due to the force of gravity).
The net effect of this is a zigzag movement of sediment up and down the beach.

179

What is longshore drift response for

Transferring vast amounts of sediment along the coastline and eventually out to sea.

180

What happens if the process of longshore drift is interrupted by coastal managment

It can lead to distortions of natural patterns

181

How do offshore currents, including rip currents, move material out to sea

At right angles to the shore. The material they transport is usually deposited some distance from the shore to form sand banks

182

When does deposition take place

When the velocity of the water or wind falls below a critical value for a particular size of particle and can no longer be transported. It occurs once the energy flow that is moving material declines

183

What are the four reasons deposition occurs

Currents may weaken or prevailing winds may lighten in strength altering the energy source.
Where opposing currents meet, turbulence may occur, resulting in deposition below the surface. Can happen at end of spit.
As waves move over the seabed or shore land features, friction occurs which results in deposition of heavy particles.
Where rivers or land slips add additional sediment to the sea deposition may occur, as energy is insufficient to transport the additional load.

184

What are areas of deposition like beaches, spits, mudflats, sand dunes and offshore bars classed as

Sediment stores or 'sinks'

185

What do aeolian processes relate to

Wind

186

What does wind play an important role in shaping

The coastline

187

How does aeolian deposition occur

During the day, wind fends to be on-shore, as the sea is usually colder than land. When there is a large tidal range, large amounts of sand may be exposed at low tide. This provides a supply of sediment that can be picked up and transported by the wind. Sand is most likely to be carried by the wind and is usually transported close to the ground and over relatively short distances.

188

What are sub-aerial processes

Land-based and include weathering and mass movement

189

What are the links to the carbon cycle and water cycle during the process of weathering

Freeze-thaw weathering and carbonation

190

Why are weathering processes common at the coast

Due to the presence of air and water, cycles of wetting and drying and exposed rock surfaces.

191

What are the three main categories of weathering

Mechanical/physical
Biological
Chemical

192

What does mechanical/physical weathering involve

The break up of rocks without any chemical changes taking place

193

What are two examples of mechanical weathering

Freeze-thaw (frost shattering)
Wetting and drying

194

Where is freeze-thaw weathering common

In latitudes where temperatures fluctuate above and below freezing and there is a ready supply of water

195

How does freeze-thaw weathering occur

Water enters cracks in the rocks and freezes when the temperature drops below 0*C.
As it freezes, water expands by almost 10%, meaning ice occupies more space and so exerts pressure on the surrounding rock.
With repeated freezing and thawing, fragments of rock break away and collect at the base of the cliff as scree.

196

What is scree used by the sea to do

Aid erosion processes such as abrasion

197

Where are wetting and drying cycles common

On the coast, where there are rocks that are rich is clay

198

What is the process of wetting and drying

The clay expands when wet and contracts and cracks when dry. Over time this can cause the rocks to break up. In addition the cracks can allow water to seep into the cliff and make them susceptible to other processes, like mass movement

199

What is involved in biological weathering

The break down of rocks by organic activity, including vegetation and coastal organisms.

200

Where is biological weathering common

Along coastlines

201

How can the roots of surface plants on cliff tops be biological weathering

They can create and expand tiny fissures. These cracks widen as roots grow which can break up the rock

202

How can sun-surface seaweed be biological weathering

It attaches itself to rocks and can weaken and detach them as it sways in the currents of stormy conditions

203

How can some organisms be biological weathering

Algae for example can secrete chemicals that aid solution (chemical weathering)

204

How can marine organisms be biological weathering

Such as the paddock (shellfish), have specially adapted shells that enable it to drill into solid rock. They are particularly active in areas of chalk

205

How can cliff nesting birds like puffins and martinis and animals like rabbits be biological weathering

They can burrow into the cliffs

206

Where is chemical weathering common

On the coast where rocks are exposed to the air and moisture so chemical processes can break down the rocks

207

What is chemical weathering

As mineral compounds undergo chemical reactions, they can alter the rock structure. Examples include oxidation, carbonation, solution and hydrolysis

208

When does oxidation occur

When rock minerals reach with oxygen. Rocks containing iron compounds experience oxidation to form a rusty red powder, leaving the rocks more vulnerable to weathering

209

When does carbonation occur

When carbon dioxide dissolved in rain water makes a weak carbonic acid (H2CO3). This reacts with calcium carbonate (CaCO3) in rocks like limestone and chalk to create calcium biocarbonate which then dissolves easily in water.

210

Where is carbonation more effective

In locations with cooler temperatures as this increases the amount of carbon dioxide that is dissolved in water

211

What is solution in terms of weathering

The dissolving of rock minerals, such as halite (rock salt)

212

What is hydrolysis

Where mildly acidic water reacts or combines with minerals in the rock to create clays and dissolvable salts, this itself degrades the rock, which makes it more susceptible to further degradation

213

What is mass movement

The downhill movement of material under the influence of gravity. It can be rapid or slow.m

214

Where are mass movement processes a common feature

On coastlines with higher relief

215

What are the processes of mass movement important in doing

Transferring energy (in response of gravity) and sediment - the sediment forms an important input to shoreline processes, forming the 'tools' for erosion and providing material to be transported and deposited elsewhere along the coastline

216

What are 6 types of mass movement

Rockfall
Landslides
Mudflow
Rotational slip or slumping
Soil creep
Runoff

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What is rockfall

Each roofs, stacks and cliff faces collapse as a weakness becomes unsupportable. Rockfalls are sudden and are often associated with steep or vertical cliffs in well-jointed and often quite resistant rock. Scree forms at the base of the cliff until material is removed by waves

218

What kind of weathering causes rockfall

Mechanical

219

What are landslides

Occur on cliffs made from softer rocks, which slip as a result of slope failure. Landslides can be triggered by heavy rain as water can lubricate less consolidated materials such as Boulder clay or weathered shales and sandstone

220

What are mudflows

Fine particles of mud flows down the face of cliffs, often heavily saturated by persistent rainfall which adds to its bulk and makes it behave more like a liquid. Mudflows are often sudden and fast flowing so can represent a natural hazard

221

What is rotational slip or slumping

Where softer material overlies much more resistant materials, cliffs are subject to slumping. With lots of lubrication, whole sections of the cliff may move downwards along a concave slide plane, producing a rotational movement

222

Where are rotational slips or slumping more common

In glacial deposits along the East Yorkshire coast

223

What is soil creep

The gradual movement downhill of individual soil particles. The presence of soil increases the likelihood of soil creep. It results in terracettes on slopes

224

What is runoff

Where overland flow occurs down a slope or cliff face, small particles may be moved downslope and onto the beach or into the sea

225

What are the different landforms of erosion

Headlands and bays
Cliffs and wave-cut platforms
Cliff profile features including caves, arches and stacks

226

What are landforms

Individual components of a landscape

227

What is a landscape

Made up of a number of landforms which give them their key characteristics

228

What does the nature of the coastal landscape depend on

The coastal geology, climate, nature of the tides and saves and a range of other factors

229

What can coasts be

Erosional or depositional
Emergent or submergent

230

Inputs of landform formation

Coastal geology
Climate
Nature of waves

231

Processes of the formation of landscapes

Erosion
Weathering
Deposition
Wave refraction
Sea level change

232

Outputs of landform processes

Sediment
Landforms

233

How do headlands and bays form

On a discordant coastline with areas of alternating more and less resistant rock erosion occurs initially faster in the areas of less resistant rock. Over time this will form bays between protruding headlands of more resistant rock

234

Why is erosional energy concentrated on headlands

Due to wave refraction

235

Why are bays the subject to deposition

Due to lower energy waves

236

What forms in bays and what do they do

Beaches and they protect the coastline from further erosion

237

On a concordant coastline how do headlands and bays form

Weaknesses in more resistant rock are exploited by the waves and erosion occurs in the less resistant rock behind

238

How do wave-cut notches form

Where destructive waves break between high and low tide lines at the foot of a cliff their energy is concentrated over a fairly small area which means that the cliff becomes undercut forming a notch

239

How do wave-cut platforms develop

When cliffs become undercut to form a wave-cut notch, the cliff above is weathered and under stress due to the lack of support from below, over time this results in the cliff collapsing. Over a series of collapses a wave-cut platform develops.

240

What does the rate of cliff collapse during wave-cut platform formation depend on

The characteristics of both the cliffs and the waves

241

Characteristics of a wave-cut platform

Fairly smooth and flat (sloping at least than 5*) and may be smoothed by further abrasion.
Unlikely to grow to wider than 500m.

242

Why is a wave-cut platform unlikely to grow wider than 500m

Over time the waves break further and further out to sea as the waves have to travel over more and more platforms before the cliffs. This means the wave energy is dissipated before it reaches the bottom of the cliff so the rate of cliff erosion decreases and the platform ceases to grow. Good example of a negative feedback loop

243

What does the steepness of the resulting cliff after a wave-cut platform forms depend on

The rock type of and rate of erosion and weathering, harder cliffs which have more recent experienced cliff collapse are likely to be steeper, softer rocks with a wider wave cut platform are likely to have a slower rate of erosion and a more gentle profile

244

Where do wave-cut platforms forms between

The high and low water mark

245

What does the formation of wave-cut platforms cause the coastline to do

Retreat

246

Example of cliff profile features

Caves, arches and stacks and their associated features

247

Why do cliff profile features tend to form on headlands

Because, due to wave refraction, wave energy is focused

248

What does whether or not cliff profile festered form depend on

The nature of the rocks and the waves

249

What forms a geo and a cave

Where there is a weakness in the rock due to a crack, fault, joint or impurity in the rock, it is exploited by hydraulic action at is enlarged and either forms a narrow, steep sided inlet called a geo or where the cliff becomes undercut a cave forms

250

What forms a blow hole

Where the cave faces the oncoming waves the full force of the waves is applied to the rear of the cave, this can enlarge joints in the cave roof and if the overlying rocks are sufficiently weakened they may collapse forming a blow hole

251

What forms an arch

Often canes form in headlands as erosion is strongest here. Where canes are eroded on either side of a headland they may erode right through the headland and form an arch

252

How does a stack form

The roof of the arch is weathered through sub-aerial processes and chemical weathering from the sea-spraying splashing below, and it's unsupported roof eventually collapses leaving a stack

253

How does a stump form

The stacks base is in the intertidal zone so it is subject to erosion. The upper part of the stack also becomes weathered and over time the whole stack collapses, usually in stages. This leaves behind a stump which will eventually be eroded to the level of wave-cut platform

254

What can the speed of erosion for forming cliff profile features range from

Between hundreds to tens of thousands of years for the entire process

255

Famous examples of cliff profile features in the UK and abroad

UK - Old Harry's Rocks in Dorset
Victoria, Australia - Twelve Apostles are a series of stacks that have associated caves and arches

256

What is the form and characteristics of depositional features controlled by

The inputs and outputs

257

When a depositional feature forms somewhere in a sediment cell, what does that mean for elsewhere in the cell

It is being eroded

258

Where does deposition usually take place

In areas where the waves are very low energy or where there is a large supply of sediment

259

What are beaches

Accumulation of sediment and represent important temporary stocks within a sediment cell

260

Where do beaches form

Between the highest point reached by storm waves and lowest Spring tides

261

What are beaches formed of

Either sand or shingle and are formed of material from offshore sandbars, longshore drift, wind blown sand from up the coast and mass movement from the cliffs behind the beach

262

Relief of a sand beach

Gentle in slope (<5*)

263

Why do sand beaches tend to be gentle in slope

Becsuse the sand grains are small and easily compactible which means little water percolates through the sand therefore the majority of water moving up the beach also returns through backwash which smooths and flattens the beach.

264

Relief of shingle beaches

Steeper (10-20*)

265

Why are shingle beaches steep

Because the larger sediment size means that it is less easily compacted and therefore the waves, having broken, percolate back through the shingle meaning that the backwash doesn't really transport material back down the beach. This creates a beach which is unlikely to be eroded

266

What are many beaches

A combination of sand and shingle

267

Why does larger sediment tend to be at the top of a beach

Because it takes high energy storm waves to deposit the material

268

What is a storm berm

At the top of a beach a wide flatter area is deposited by a strong swash during spring high tide. Won't be affected by normal swash.

269

What are berms

Below the storm berm. These are a series of ridges that mark a series of high tide lines and are built by constructive waves

270

When do cusps on a beach form

Where the waves break directly onto the beach. Both swash and backwash are strong and generally equal to each other. They generally form at the junction where the sand on the lower part of the beaches meets the shingle on the upper part of the beach. The cusps curved sides channel incoming swash into the centre of the cusp which creates a stronger backwash flowing out of the centre of the cusp which further deepens the cusps

271

What are ripples

Further down the beach than cusps, ripples may form in the sand due to the action of the tides moving back and frothed across the sand

272

Where do ridges on a beach form

At the low water mark where backwash deposits sediment. They run parallel to the coast and are broken by runnels where water runs through to return to the sea.

273

What are the two types of beaches

Swash-aligned and drift-aligned

274

What is a swash-aligned beach

Waves are parallel to the coast so backwash is at the same angle so beach can build up

275

What is a drift-aligned beach

Waves approach at an angle so long shore drift occurs. Sediment may be graded with fined and rounder sediment down-drift as it is easier to transport. These beaches result in spits, tombolos and barrier beaches

276

Where are swash aligned beaches usually found

On irregular coastlines where longshore drift is impeded, and waves hit sections of the coast head-on

277

What are spits

Long, narrow ridges of deposited sediment which are joined to the mainland at one end and stick out into the sea or across an estuary or bay

278

What are the two types of spits

Simple or compound

279

What are simple spits

Either straight or recurved but do not have minor spits or recurved ridges along their landward edge

280

What are compound spits

Have a series of minor spits or recurved ridges along their landward side which may show their former position

281

Example of a simple spit

Spurn Head, Humberside
Sandy Hook Spit, New Jersey, USA

282

Example or a compound spit

Hearst Castle Spit, Hampshire

283

How do spits form

Where material is moved along the coast through longshore drift but where the coastline changes direction (often due to an estuary or river mouth) sediment starts to build up in the sheltered lee of the headland which begins to form a spit.

284

What makes a spit more permanent

During a storm larger material is deposited above the high water mark

285

What extends a spit further

Finer material continues to be moved along the spit through longshore drift and into the deeper water of the estuary/bay where enemy is lost and the sediment is deposited which extends the spit further. In some cases if the spit is growing across a river mouth turbulence where the river current and the coastal currents meet may cause further deposition

286

When may the end of the spit become recurved

As wave refraction and secondary winds and waves carry and deposit sediment round the end of the spit

287

What forms a compound spit

If the end of the spit recurves enough this is another change is coast line direction so the spit may continue to grow in the original direction. This may happen a number of times creating a compound spit.

288

What forms a salt marsh

A river flowing out to sea is likely to prevent the spit from growing right across an estuary but very fine sediment may be deposited by the river in the 'slack' low energy zone behind the spit. This forms a salt marsh which is an important coastal habitat

289

What may salt marshes be stabilised by

The growth of salt-tolerant plants

290

How does a tombolo form

Where a spit connects an island to the mainland

291

Example of a tombolo

St Ninian's in Shetland

292

Why may the formation of a tombolo lead to salt marsh formation

The formation of the tombolo creates more sheltered conditions on the lee-side of it which may lead to deposition thus also salt marsh formation

293

When do barrier beaches form

Where a spit extends across a bay or joins two headlands together. They can only form where there is no current flowing off the land.

294

Example of barrier beach

The south coast of the UK including Slapton Ley, Devon

295

When are most barrier beaches thought to have been first formed

When gravel deposited in the English Channel when glaciers melted after the last Ice Age was deposited on the coast by constructive waves, forming the barrier beach. Longshore drift has since added more material to these.

296

What does the formation of barrier beaches and the subsequent deposition of sediment from longshore drift show

That landforms can be the product of a number of processes over a range of timescales

297

What forms behind a barrier beach

A lagoon which is usually shallow and marshy and in tropical locations mangroves can form

298

Overtime what happens to lagoons

They become full of silt and eventually dry up

299

When do barrier islands form

Where barrier beaches become separated from the mainland

300

Characteristics of barrier islands

Made of sand or shingle
Long (up to 100 miles long)
Narrow
Becoming vegetated as they get older and vegetation succession occurs

301

While the formation isn't entirely understood, what is thought to be the formation of barrier islands

Though they are formed of sediment deposited when glaciers melted 18,000 years ago at the end of the last ice age. It's probable that currents deposited this material in barrier beaches and that the melting ice also mean that sea levels rose leaving these beaches separated from the mainland.

302

Where are barrier beaches usually found

In areas with low tidal ranges and gently sloping offshore coastlines

303

In some cases, why do very long barrier islands get split into a series of shorter islands

Inlets develop between them to allow tides to rise and fall around the island

304

Example of barrier island

The West Frisian Islands in the Netherlands - they have marsh between the islands and the mainland and tidal inlets between them

305

How are offshore bars formed

Sediment deposited by costal currents including longshore drift but they remained submerged or semi-submerged offshore beyond the breaker zone. They are formed where currents deposit sand off-shore.

306

Along the Uk, what results in winds blowing onshore

Local differences in air pressure as the wind blows from the high pressure over the sea (the sea is cooler than the land) to the lower pressure area of the land (the land is warmer than the sea)

307

What does onshore wind mean

They sand is transported up the each through saltation

308

What do areas which have a high tidal range have

Large expanses of sand which are exposed and can dry out at low tide and therefore more likely to have sand dunes forming

309

What provides sources of sand for sand dune formation

Onshore wind
Offshore sand bars
Areas which have a high tidal range and large expansion of sand

310

What are the stages of sand dune formation

1. Sand is trapped by an obstacle. Often on a storm berm where driftwood is deposited.
2. More sand is trapped so obstacle grows, slowing the wind and contributing to further deposition.
3. First dunes are called embryo dunes which can be colonised by pioneer species. Plant root stabilises the dune and decaying plant matter adds organic content to the sand.
4. As dunes grow they become out of the reach of high tide and are known as yellow dunes.
5. More sand accumulates and plants continue to grow and add organic matter to dunes, they become fixed and 'grey' as the humus (organic content) increases.
6. Dune slacks may form between the dunes where the water table is at the surface.
7. Inland from grey dunes, you find mature dunes or dune health/woodland. This is the final stage in succession called the climax vegetation.
8. Within the system it is possible to find blowouts where the wind has been funnelled through the areas and has removed the sand. Wildlife of human activity can often be a catalyst for the formation of blowouts.

311

Example of pioneer species

Marram grass and sea couch

312

What are the characteristics of embryo dunes

1 m high and 80% exposed sand, low water table

313

Characteristics of yellow dunes

5m high and 20% exposed sand, rising water table

314

Characteristics of grey dunes

8-10m high and less than 10% exposed sand, rapidly rising water table

315

What are grey dunes able to support

Larger plants which require more water and organic matter such as gorse bushes

316

What forms in dunk slacks

Aquatic ecosystems

317

What is found in mature dunes

Hardy trees such as birch and shrubs like fodder broom and heather grow which further increase humus levels, moisture retention and decreases the pH. this is called the climax vegetation

318

What is the process of succession started on sand known as

A psammosere succession

319

What is the pH of embryo dunes

8.5 (alkaline)

320

Foredune/yellow dune

7.5 (alkaline but almost neutral)

321

What is the Ph of mature dune

6 (acid)

322

Which are the mobile dunes and the fixed dunes

Embryo + foredune and yellow dune are mobile whereas grey dunes are fixed

323

Where are the largest sand dune in the Uk

West coast

324

Example of a sand dune

Studland Bay near Southhampton

325

Examples of estuarine landforms

Mudflats and salt marshes

326

Where do estuarine landforms form

On low energy coastlines and in areas of lower energy such as river estuaries where tidal currents are slowed down or behind spits where slack (low energy) water is found

327

How do mudflats form

In estuaries or behind spits slow flowing water from the river carrying lots of suspended sediment meets saline sea water which causes flocculation to happen as clay particles aggregate (join together). These larger, heavier, clay particles sink to the bed of the estuary. At low tide in the inter-tidal area this mud is exposed with water left flowing in channels between the mud flats.

328

Over time what can mudflats become

Salt marshes

329

Where are the largest mudflats and salt marshes in the UK

Morecambe Bay in Lancashire

330

Like sand dunes, what can the formation of mudflats and salt marsh ecosystems be described as

A step-by-step sequence of succession. This is called a halosere

331

What is a halosere

Salt-tolerant succession/ecosystem

332

What is the halosere of mudflats and salt marshes

1. Vegetation like eelgrass begins to grow.
2. This slows currents down which leads to more deposition although it's uneven depending on where the eelgrass is.
3. Pioneer species begin to colonise the area (these are halophytes).
4. Deposition continues and the plants continue to grow and die which raises the surface of the marsh. As this happens the mudflats are submerged for shorter periods of time and the mudflats become a salt marsh.
5. more complex flowering species like sea lavenders become established as they are less tolerant to salt than the pioneers.
6. More deposition occurs and vegetation becomes more dense which further raises the surface level and soil conditions improve.
7. Where the marsh rises above the level of Spring high tide trees and scrub starts to grow as the climax vegetation.
8. As the land rises above sea level, rushes and reeds become established, eventually leading to the growth of trees such as alder, ash then oak to complete the succession.

333

Why do eelgrass not count as a pioneer species

It is a sea plant

334

What does a halophytes vegetation mean

Salt-tolerant

335

Example of a pioneer species that grows on a mudflat

Spartina (e.g cordgrass) which is the dominant vegetation of the Uk

336

Why is spartina the dominant vegetation on Mudflats in the UK

As it has a fine mat of roots, which binds the mud together and thus traps more sediment

337

What does climax vegetation mean

The natural end-point of succession

338

In reality, why is the climax vegetation not always reached in estuarine landforms

As farmers graze sheep on the salt marsh (in some puns you can order salt-marsh lamb for Sunday lunch)

339

What are the characteristics of coastal landscapes that we see today the result of

The factors that shaped them during the Holocene (roughly the time since the end of the last glacial period some 12,000 years ago)

340

What are the range of factors important in producing the present coastal landscape features

Local tectonic activity.
Sea level change - global and local.
Climatic change - natural and that enhanced by human activity.
Changing ocean currents and wave regimes.
Natural disaster or events like tsunami.
Changing sources, types and amounts of sediment.
The changing nature of humans activity.

All of the above have continually changed over the millennia but will have left their mark as features in the coastal landscape of the present day, where contemporary costal processes will inevitably continue to alter and modify them further,

341

Characteristics of mature dunes

6-8 metres and high water table

342

Example of mudflats in the USA

Cape Cod and Plymouth Bays off Massachusetts

343

What are the functions of Spartinas two root systems

A fine mat of surface roofs to bind the mud and long, thick, deep roots that can secure up to 2 metres of deposited material. This enables the plant to trap more mud than other pioneers, and thus it has become the dominant vegetation on tidal flats in the British Isles

344

Where may hollows form on a salt marsh

Where seawater becomes trapped and evaporates, leaving salt-pans in which the salinity is too great for plants to survive.

345

What are the two ideas relating to sea level change

Eustatic change
Isostatic change

346

What do changes in sea levels create

Distinct landforms of emergence (falling sea level relative to the land) and submergence (rising sea level relative to the land)

347

What is isostatic sea level change

A change in the level of the land relative to the sea as a result of the changing level of the land.

348

Examples of isostatic sea level change

Contentment’s collide and fold mountains form the land is forced to rise up out of the sea

349

What are the changes of isostatic sea level change

Local/regional

350

What ads the scales of isostatic sea level change

A rise or fall in the sea level as a result of a change in the actual level of the water in the oceans.

351

Example of eustatic sea level change

Temperatures increase water expands meaning that sea levels rise when sea temperatures are warmer

352

What are the scales of eustatic change

Global changes

353

18,000 years ago, what were sea levels like

Last glacial maximum: sea levels were on average 110m below their current level which meant the the UK was joined to mainland Europe and Scandinavia by a large land bridge where the North Sea now is called Doggerland.

354

10,000 years ago, what were sea levels like

The northern North Sea was flooded and the coastline and Europe was beginning to look as it does today but Doggerland still linked what is now the UK to what is now the Netherlands and Denmark

355

9,500 years ago, what were sea levels like

They rose rapidly in 500 years

356

Prior to the industrial revolution, what were sea levels like

Fairly stable for about 3000 years

357

Recently, how much have sea levels risen

6cm on average from the mid-19th century and 19cm during the 20th century. Current sea levels are rising at 3.2mm per year

358

Why are current sea levels rising at 3.22mm per year

Due to thermal expansion

359

What is the predicted increase in sea levels for 2100

4-6m rise although this could be greater depending on how Greenland and Antarctic ice sheets respond to warming temperatures

360

What is stage 1 of a typical sequence of sea level rise that reflects the advance and retreat of the ice

As climate gets colder, marking the onset of a new glacial period, an increasing amount of precipitation falls as snow. Eventually, this snow turns to glacier ice. Snow and ice act as a store for water, so the hydrological cycle slows down - water cycled from the sea to the land (evaporation, condensation, then precipitation) does not return to the sea. As a consequence, sea levels falls and this affects the whole planet. Such a worldwide phenomenon is known as a eustatic fall.

361

What is stage 2 of a typical sequence of sea level rise that reflects the advance and retreat of the ice

The weight of ice causes the land surface to sink. This affects only some coastlines and then to a varying degree. Such a movement is said to be isostatic and it moderates the eustatic sea level fall in some areas.

362

What is stage 3 of a typical sequence of sea level rise that reflects the advance and retreat of the ice

The climate begins to get warmer. Eventually the ice masses on the land begin to melt. This starts to replenish the main store and sea level rises worldwide (eustatic). In many areas this floods the lower parts of the land to produce submergent features such as flooded river valleys (rias) and flooded glacial valleys (Fjords)

363

What is stage 4 of a typical sequence of sea level rise that reflects the advance and retreat of the ice

As the ice is removed from some land areas they begin to move back up to their previous levels (isostatic readjustment). If the isostatic November is faster than the eustatic, then emergent features are produced such as raised beaches. Isostatic recovery is complicated as it affects different places in different ways. In some parts of the world it is still taking place as the land continues to adjust to having masses of ice removed. Today, the southeast of the British Isles is sinking while the northwest is rising. This reflects the fact that the ice sheets were thickest in northern Scotland and that this was the last area in which the ice melted.

364

What are the 3 cause of isostatic change

Tectonic activity.
Glaciation.
Post-glacial readjustment.

365

How is tectonic activity a cause of isostatic activity

Land can move up or down as a result of tectonic activity. This could be a few meters as a result of one event

366

Example of small scale tectonic activity causing isostatic activity

The Tohoku earthquake in Japan in 2011 some sections of the coastline dropped 0.84 meters.

367

Example of large scale tectonic activity causing isostatic activity

Fossils in the Andes, Alps and Himalayas all show that the rocks found in these fold mountains were once in the ocean floor, but have been forced up thousands of meters as part of the formation of the mountains

368

What is glaciation

During an ice age glaciers and eventually ice sheets form over the land in areas cold enough. This causes the land surface to become pressed into the upper layer of the mantle (the asthenosphere) and therefore relative sea levels rises.

369

What is post-glacial readjustment

Following the melting of ice sheets and glaciers on land the land is able to rise back up as the asthenosphere rebounds. This is called isostatic recovery

370

Why is isostatic recovery responsible for falling sea levels in Scotland

During the last ice age Scotland was the part of the UK covered with the thickest ice and melted last

371

How does isoline maps show isostatic sea level change across the UK

Positive numbers show land rising, negative numbers show falling land relative to sea level

372

What are the three causes of eustatic change

Thermal expansion of water
Changes in ice sheet extent.
Tectonic activity.

373

How is thermal expansion of water a cause of eustatic change

As water is heated it expands so even if the mass of the ocean (the total amount of water) stays the same. Warmer water has a larger volume so takes up more space and sea level therefore rises

374

How are changes in ice sheet extent a cause of eustatic change

Where ice forms on land during a glacial period it removes water from other stores including the the ocean so sea lev is fall. When ice on land melts there is less water locked up in ice on the land so more available to other stores including the ocean and therefore sea levels or rise

375

How is tectonic activity a cause of eustatic change

Where new land is being formed under the ocean, usually at mid-ocean ridges, this new rock/crust takes up space in the ocean basins, which would have been occupied by water so the water is displaced and sea levels rise. Times of higher amounts of volcanic activity at mid ocean ridges have higher eustatic sea levels and times of lower amounts of volcanic activity have lower eustatic sea levels.

376

What is total sea level change

The balance between isostatic and eustatic change

377

What is the total sea level change in Scotland today

Isostatic recovery is changing the level of the land to rise faster than thermal expansion and melting ice sheets are causing sea level to rise so the overall effect is that sea level is falling in Scotland and landforms of emergence are forming

378

What have coastlines of emergence been subject to

A fall in sea level whether this is as a result of eustatic or isostatic change or, more likely, as a combination of the two

378

All along the West Coast of Scotland what has isostatic recovery resulted in

The formation of distinct landforms of emergence

378

How do raised beaches form

Where the sea level drops relative to the land so what was a beach becomes stranded above the high water mark

378

Where are raised beaches common

On the West Coast of Scotland, for example on Arran

379

What are relict feature

Marine features such as courts and cliff profile features like caves that are left above the high tide level in which case they are called relief features e.g relict cliffs

380

Example of a relict features

Kings Cave on Arran

381

Why may raised beaches appear as flat, grassy terraces

They are subject to vegetation succession once above the high tide level

382

Why do wave cut (marine) platforms look like once left exposed above the level of the current wave cut platform

Less visible as they may well be covered in beach sediment from the current beach

383

What have coastline of submergence been subject to

A rise in sea level whether this is as a result of eustatic or isostatic change or, more likely, as a combination of the two

384

Why can a number of distinct features of submergence be seen along the south coast of England

As the isostatic tilt of the UK results in rising sea levels relative to the land as the land sinks

385

What are rias

Flooded river mouths/valleys

386

How do rias form

Where the sea level rises relative to the land, river valleys flood and appear as coastal inlets with relatively steep coastlines where the old valley sides are and the floodplain has been flooded by the sea

387

Example of a ria

The mouth of the river exe at Exmouth.
Poole Harbour (near studland Bay). They make excellent harbours

388

What is a fjord

They are flooded valleys however they are flooded glacial valleys. They can often be very long

389

Why do Fjords have very steep, often near vertical, sides

When glaciers erode they creep steep sided, U-shaped valleys

390

Why is the mouth of the fjord often shallower than further inland

Glaciers can overdeepen their valley so this is often the case

391

Example of a Fjord

The Songnefjord in Norway in Norway is over 200km long from the sea to the head of the fjord

392

When do Dalmatian coasts occur

Where river systems which once ran parallel to the coast (generally due to concordant geology) are flooded resulting in a series of long islands which would once have been the hills along the valley sides parallel to the coastline

393

What are the landforms on the coastline of submergence

Rias
Fjords
Dalmatian coasts

394

What is the key difference between rias and Fjords and Dalmatian coasts

Rias and Fjords run perpendicular to the coastline, Dalmatian coast islands and peninsulas run parallel to it

395

Example of a Dalmatian coast

Croatia

396

Globally, how is sea level increasing

Eustatically as climate change causes thermal expansion and the melting of ice sheets

397

While sea levels are increasing globally, what may some coastlines experience

Localised sea level fall due to isostatic factors

398

What does how much sea levels increase by vary according to

Predictions of how much warming is likely to occur and how the Antarctic and Greenland ice sheets are likely to respond

399

What do average predictions of sea level increase vary between

18 and 59 cm compared to 1990 by 2090

400

What are changes in sea level the result of

Two processes: increases in the volume of the ocean, subsidence of the ocean

401

What are the 9 impacts of sea level change

Major centres of UK population including London, Hull and Middlesbrough are at risk from inundation.
Lots of UK agricultural land could be lost through both flooding and increased coastal erosion.
Major road and rail links such as the east coast Mainline are at risk.
Numerous power stations and gas and oil terminals which are often built along the coast risk flooding.
Ground water may become contaminated with sea water resulting in it becoming unstable.
River flooding may increase in frequency as rising sea level reduces the gradient of the long profile of the river.
Loss of coastal habitats such as mangroves.
Submergence of low-lying islands like the Maldives.
Migration away from coastal areas, in Bangladesh alone 11% of land is likely to be permanently flooded.

402

Where is there valuable arable land in the UK

Along the east coast

403

What are coastal systems a product of

A series of processes acting at a range of scales over a range of timescales from hourly changes in tide levels to geological-time scale changes in continental movement

404

What does any coastline have

A range of features formed by past processes but present processes are also acting upon these

405

Example of landforms created by past processes but present processes are acting upon it

Raised marine terraces in Scotland are still being affected by present-day erosion at high tide

406

What is really important to understand about a coastal landscape

It is made up of a combination of short-duration, medium-term and long-term ones

407

What landforms are current systems in coasts likely to be responsible for

The current systems are responsible for more recent features but they are likely to be modifying relict (previous) ones

408

What are the aims of coastal management

To provide defence against, and mitigate the impacts of flooding.
To provide protection against, and mitigate the impacts of coastal erosion.
Stabilise beaches affected by longshore drift.
Stabilise sand dune areas.
Protecting fragile estuarine landscapes.

409

What are the four defence options

Hold the line
Do nothing but monitor
Retreat the line
Advance the line

410

What is hold the line

Retain the existing coastlines by maintaining current defences or building new ones where existing structures no longer provide sufficient protection

411

What is do nothing but monitor

On some stretches of coastline it is not technically, economically or environmentally viable to undertake defence works. The value of the built environment here does not exceed the cost of installing coastal defences.

412

What is retreat the line

Actively manage the rate and process by which the coast retreats

413

What is advance the line

Build new defences seaward of the existing line

414

What is hard engineering

Involved building of entirely artificial structures using various materials such as rock, concrete and steel to rescue or stop the impact of coastal processes

415

Example of a sea wall

Minehead, Somerset
Norfolk

416

What is a sea wall

Concrete barrier along the coast that absorbs the energy of the waves. Sometimes they are curved in order to deflect the wave back out

417

Advantages of sea wall

Effective and will stop erosion.
Protects the coastline.

418

What are the disadvantages of sea walls

Have to be maintained and repaired.
Expensive to repair.
Looks ugly and not natural.
Last 100 years, deflecting the waves can make the base of the wall weak and therefore they require the constant maintenance throughout this period

419

Cost of sea wall

£6,000 per metre + maintenance

420

Example of groyne

Minehead, Somerset.
Norfolk

421

What is a groyne

Traditionally these are wooden but recently they are rock. They rescue the route at which longshore drift carries material along the beach by trapping it on one side

422

Advantages of groynes

Creates a bigger beach to help protect the coast from the sea.
Relatively cheap.

423

What are the disadvantages of groynes

More erosion on cliffs.
Preventing the sand from moving can cause erosion rates to increase further down the coast.
Only last around 30-40 years.

424

Cost of groynes

£1000 per metre if wooden and £1000 per cubic metre if rock

425

Example of rock armour

Minehead, Somerset.
Norfolk.

426

What is rock armour

Made from granite or other hard rocks. Placed at the base of a cliff to absorb the energy of the waves but let water drain through them.

427

Advantages of rock armour

Relatively cheap.
Last around 120 years.
Use natural resources e.g rock.

428

Disadvantages of rock armour

Still let some water through so some erosion still takes place.
Looks environmentally ugly.
Sustainable sourcing as it can be taken from a quarry.

429

Price of rock armour

£1000 per metre

430

Example of revetments

Norfolk

431

What are revetments

Slipping concrete or wooden defence facing the sea. Wooden structures also trap the beach material.

432

Advantages of revetments

Absorb the wave energy.
Better looking than a sea wall.

433

Disadvantages of revetments

Wooden structure lasts around 10 years.
Concrete ones last 30 years.
Less durable than a sea wall and need replacing quicker.
Don’t give total protection to the base of the cliff.

434

Price of revetments

Up to £4500 per metre

435

Example of offshore break water

Elmer Beach, West Sussex

436

What are offshore break water

Built parallel to the coast, it is off the coast and made of rock. Waves are faced to break before they reach the shore and reduces wave energy

437

Advantages of offshore break waters

Increase in wildlife.
Very effective at reducing the energy or the waves.
Out to sea so don’t spoil the beach.

438

Disadvantages of offshore break waters

Implications for fishermen.
Very expensive.
Being out at sea means they can be tricky to maintain.

439

Cost of offshore break water

£1.3 million for one

440

What is soft engineering

Trying to work with the physical and natural processes within an area rather than building large man made structures to protect the land form a wave attack

441

Example of beach replenishment/ beach nourishment

Miami Beach

442

What is beach replenishment

Sand is replaced along the beach. Done by taking material from sea bed and dumping it on to shore.

443

Advantages of beach replenishment

Makes the beach more effective at dispersing the energy of the waves.
Replaced material lost by longshore drift.
It’s attractive as beach looks untouched.

444

Disadvantages of beach replenishment

Does not prevent long shore drift so it has to be done repeatedly, making it expensive.
Involves using a dredger which is noisy upsetting tourism.
Kills marine life from sea bed.

445

Cost of beach replenishment

£3000 per meter but has to be done once or twice a year

446

What is managed retreat

Involved allowing the coast to take back the land, by removing existing sea defences and allowing the land behind them to flood. Overtime land becomes marshland allowing habitats to form

447

Advantages of managed retreat

New habitats.
Marsh acts as a natural sea defence protecting the land behind it from erosion.
A fairly cheap sea defence.

448

Disadvantages of managed retreat

Some people may not agree over which land should be flooded causing conflict.

449

Cost of managed retreat

Cost is variable

450

What is cliff regrading and drainage

Reducing the angle of a cliff to stabilise it. Drainage removes excess water to prevent landslides and slumping.

451

Advantages cliff regrading and drainage

Cheap.
Very effective on clay or loose rock cliffs but not rock like chalk.

452

Disadvantage of cliff regrading and drainage

Causes soul to dry out.
Some homes may need to be demolished as it effectively causes retreat.
If cliff drys out too much it may cause it to crumble and collapse.

453

Cost of cliff regrading and drainage

£200-2000 per 100m
£2-20per meter

454

What is dune stabilisation

Methods such as planting of marram grass and fencing off areas are employed to protect the dunes from erosion

455

Advantages of dune stabilisation

Maintains a natural coastal environment.
Provides wild life habitats.
Cheap and sustainable.

456

Disadvantages of dune stabilisation

Time consuming.
May still be eroded if people ignore signs to stay off certain areas.

457

Cost of dune stabilisation

Variable

458

Since the 1990s what have UK governments focused on with management and mitigation of coastal floods and erosion

Sustainability

459

What are examples of sustainable approaches to coastal management

Shoreline management plans and
Integrated coastal zone management

460

When was the integrated system of Shoreline Management Plans (SMPs) introduced

In 1995 to avoid a piecemeal approach to management

461

How many SMPs are around the coast of England and Wales and what do they corespond with

22 and they correspond with the sediment cells and sub-sediment cells

462

What are SMPs designed to identity

The most sustainable approach to managing the flood and coastal erosion risks to coastlines

463

What do SMPs aim to plan for

Short term (0-20years)
Medium term (20-50)
Long term (50-100)

464

What are the key features of the SMPs

Provide an assessment of the risks associated with the evolution of the coast.
Provide a framework to address the risks to people and to the developed, historical and natural environment.
Address risks in a sustainable way.
Provide the policy agenda for coastal defence management planning.
Promote long term management policies for the twenty-second century.
Aim to be technically sustainable, environmentally acceptable and sustainable economically viable.
Ensure management plans comply with international and national nature conservation and biodiversity legislation.
Incorporate a ‘route map’ to allow decision makers to make changes to the short term and medium term plans to ensure long term sustainability is maintained.
Provide a foundation for future research and the development of new coastal management strategies in the future.
Are ‘live’ working documents to be continually reviewed and updated, setting new targets for future management objectives.

465

What does each SMP describe

How each management unit, or stretch of coastline covered by the plan, is to be managed e.g hold the line, do nothing, managed retreat or advance the line

466

Where did the term ‘integrated coastal zone management’ originate from

The UN Earth Summit of Rio de Janiero in 1992

467

Where were the guidelines about how ICZM should operate set out

In the Agenda 21 documents released following the summit

468

What does the European Commission describe ICZM as

Integrated coastal management aims for the coordinated application of the different policies affecting the coastal zone and related to activists such as nature protection, aquaculture, fisheries, agriculture, industry, offshore wind energy, shipping, tourism, development or infrastructure and mitigation and adaption to climate change. It will contribute to sustainable development of coastal zones by the application of an approach that respects the limits of natural resources and ecosystems, the so-called ‘ecosystems-based approach’.

Integrated coastal management covers the full cycle of information collection, planning, decision making, management and monitoring of implementation. It is important to involve all stakeholders across the different sectors to ensure broad support for the implementation of management strategies

469

Why did the European Commission, Following Rio develop its framework for ICZM

To promote integrated coastal management.

470

What was the background to the ICZM initiatives

Coastal zones are some of the most economically productive areas in the world.
The natural assets of coasts have for millennia made them popular for:
-settlements
-tourist destinations
-business centres
-port.
Around 200 million people live near Europe’s coastline.
The Commission feels this concentration of people and economic activity is putting great pressure on our coastal environment and creates excessive exploration of natural resources, all of which leading to: biodiversity loss, habitat destruction, pollution, conflicts between stakeholders, overcrowding in some locations.

471

Why does the European Commission suggest that the revised ICM initiative is required

They are some of the areas most vulnerable to climate change and natural hazards.
Coasts are especially at risk of: flooding, erosion, sea level rise, extreme weather events.
The life’s of people in many coastal communities are already changing due to the impacts of these issues.

472

In the past, what was coastal management often viewed as having

A sectoral approach, where the local authorities made decisions for their stretch of coastline and other agencies and interest groups tries to manage their particular environment, cause or social group

473

Why was a sectoral approach to coastal management not good

In the view of the European Commission, this led to decision that undermined each other, an inefficient use of resources and failure to meet sustainability objectives

474

What is ICZM designed to do

Integrate the interests of all stakeholders to avoid conflict. It aims to co-ordinary policies that affect the coastal zone and the activities that take place there

475

What coastal activities does the ICZM aim to co-ordinate policies for

Nature conservation/protection
Aquaculture (farming marine organisms like lobsters)
Fishing
Agriculture
Industry
Offshore wind energy
Shipping
Tourism
Infrastructure development
Development to adapt to and mitigate climate change

476

What approach does the ICZM employ

An ‘ecosystem-based approach’ that operates within the limits of natural resources and ecosystems

477

If operated properly, how should ICZM operate

In a cycle with each stage generating feedback to be addressed by the following stage

Information collection -> planning -> decision making -> managing and monitoring of implementation and then back to the beginning

478

In March 2013, what did the European Commission launch

A directive to establish a framework for maritime spatial planning (MSP)

479

What was MSP launched to do

Build on and work alongside ICZM by adopting some of the techniques already employed by land-use planners.

480

What is often involved in MSP

Mapping the activities of all stakeholders in a particular coastal zone, so that all those involved can visually assess the cumulative impact of their actions on a particular ecosystem. This can then inform future plans.

481

What techniques does MSP utilise

Powerful GIS and geo-spatial mapping because various scenarios can be visually played-out to help agree upon the most sustainable way forward

482

What is MSP hopes to play an integral role in

Improving the interaction between sea and land based activities including:
Connecting offshore wind turbines to the electricity distribution network on land.
Assessing the impacts of strategies to protect coastlines against erosion and flooding on activities like aquaculture and fisheries, and their impacts on marine ecosystems.

483

Examples of observational and measurement techniques to collect quantitative data in a coastal system

Annotated field-sketches.
Measuring: characteristics of waves e.g if they are constructive, the movement of material by longshore drift, the size and shape of beach sediment, the gradient of beaches and sand dunes - beach and dune profiles, wind direction and speed and the dimensions and characteristics of coastal landforms.
Other techniques can be used to identify, measure and map the types of sea defences used along a coastline.

484

What does coastal fieldwork produce

Quantitative data that is easily mapped using a range of geo-spatial mapping techniques to give a clear visual representation of the findings of the research

485

What kind of assessment is required when looking at many aspects of a situation

A holistic assessment

486

What are the different situations needing to be looked at on a coast

The challenge of mitigating the worst impacts of any sea level rise.
Improving resilience of communities.
Helping them adapt to their changing circumstances.

487

What are some examples of qualitative techniques in coastal landscapes

Participant observation and in-depth interviews.
On a local level, questionnaires and interviews

488

How are participant observation and in-depth interviews good techniques to collect data in the coastal landscape

They would be one way of engaging with the views of the populations knocked to inform the development of bottom-up solutions to further issues. This would be good with marginal coastal communities of Southern Bangladesh

489

How can questionnaires and interviews be used with coastal communities in the British Isles

To assess the views of various stakeholders about any proposed sea defences for a particular stretch of coast. The qualitative results of such surveys could then be analysed alongside more empirical data about factors such as financials cost and impacts on natural coastal processes to produce thorough cost-benefit or SWAT analyses of any proposed coastal management schemes, that include the view of all stakeholders.