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AS Geography > Unit 1 - Changing landscapes > Flashcards

Unit 1 - Changing landscapes Flashcards

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1
Q

What are coastal inputs?

A

Energy from wind, waves and tides: sediment from weathering and erosion processes.

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2
Q

What are coastal outputs?

A

Sediment removed by longshoredrift and sediments deposited as landforms, such as dunes.

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3
Q

What are coastal transfers?

A

Processes of erosion and transportation that can move sediment around the system.

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4
Q

What are coastal stores?

A

Sediment deposited in landforms.

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5
Q

What is the coastal sediment coastal budget?

A
  • when sediment input = output, the budget is balanced (in a steady state equilibrium)
  • if factors such as human activity reduce the sediment input, the budget will be out of balance
  • when the system in one place is out of balance, it can increase erosion further along the coastline
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6
Q

What is a sediment cell?

A

A stretch of coastline where the sediment budget is self contained. Also known as a littoral cell.

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7
Q

How many sediment cells are there in england/wales?

A

11 major cells divided into smaller sub cells

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8
Q

What are the 3 types of equilibrium?

A

Steady state
Metastable
Dynamic

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9
Q

What is a steady state equlibrium?

A

Changes in energy and the resulting change in coastlines do not vary much from the long term average conditions.
- example seasonal changes, but average gradient stays the same

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10
Q

What is a metastable equilibrium?

A

The coastal zone changes from one state of equilibrium to another due to an event causing a change in conditions.
- example sedimental removal from dredging, there is a new equlibrium with a reduced beach

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11
Q

What is a dynamic equilibrium?

A

The state of equiliibrium changes over a longer timescale than metastable equilibrium
- example climate change, changing beach profiles gradually

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12
Q

What is the difference between positive and negative feedback?

A

Positive feedback - increases the initial change that had occured
Negative feedback - reduces the effect of the change, helping the coast return to its original condition

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13
Q

What are tides?

A

Rise and fall of sea level

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14
Q

How are tides created?

A

By the gravitational effect of the moon which pulls water towards it to create high tides, with a balancing increase in sea level on the opposite side of the earth.
Between these two areas, the sea level is lower, creating low tides.

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15
Q

What are spring tides?

A

Twice a month the earth, sun and moon are aligned, so the gravitational pull is greatest, creating higher than average tides.

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16
Q

What are neap tides?

A

When the sun and moon are at right angles to each other the oppositional pull weaker, creating lower than average tides.

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17
Q

What are semi-diurnal tides?

A

2 high tides and 2 low tides every 24hrs

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18
Q

What are diurnal tides?

A

One high tide and one low tide every 24hrs

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19
Q

What are the 3 types of currents?

A

Tidal
Shore normal
Longshore

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20
Q

What are tidal currents?

A

Water floods the intertidal zone at high tide, moving and depositing sediment . As the tide falls (ebb) sediment moves in the reverse direction

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21
Q

What are shore normal currents?

A

Waves align parallel to the coastline, pushing water straight up the beach. Water returning directly away from the shore can form strong, fast moving channels of water called ripcurrents

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22
Q

What are longshore currents?

A

Waves approach the shoreline at the oblique angle but return straight down the beach, moving sediment parallel to the shore.

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23
Q

How are waves created?

A

Transfer of energy from the wind blowing over the sea surface
Stronger winds increase fictional drag and the size of waves.

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24
Q

Features of a constructive wave?
HLPSE(SB)MG

A
  • wave height of less than 1 metre
  • wave length of up to 100m between crests
  • longer waves periods (6-8 breaking each minute)
  • gentle steepness
  • low wave energy
  • stronger swash
  • sediment moves up beach to form a berm
  • increase gradient of upper beach
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25
Q

Features of a destructive wave? HLPSE(SB)MG

A
  • wave height greater than 1 metre
  • shorter wave length (20m between crests)
  • shorter wave period (10-14 breaking each minute)
  • steep steepness (plunging)
  • high wave energy
  • stronger backwash
  • sediment moves down beach
  • steeper upper beach, gentle lower beach
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26
Q

When are destructive waves more common?

A

More frequent in the winter with stormier weather because of the jet stream steering more atlantic depressions over the UK during the winter.

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27
Q

What are high energy coastal environments?

A

Erosive, rocky coastlines

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28
Q

What processes affect high energy coastal environments?

A
  • physical, chemical and biological weathering
  • mass movement
  • transportational processes
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29
Q

What are examples of a high energy coastal landform?

A
  • cliffs
  • wavecut platforms
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30
Q

What is the dominant process in low energy coastal environments?

A

Deposition of material, creating sandy coastlines.

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31
Q

What are examples of low energy coastal landforms?

A

Sandunes, spits and bars

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32
Q

What can develop at an estuarine coastline?

A

Mudflats

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33
Q

What 3 things do wave type depend on?

A
  • wind velocity
  • length of time wind has blown across the water
  • the fetch
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34
Q

What is the ‘fetch’ of the wave?

A

The distance the wind has blown over the water

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35
Q

What are the 4 stages of wave refraction?
friction - direction - energy - result

A
  • friction from the seabed in shallow water slows the progress of waves
  • waves change direction, so that they approach the coastline aligned parallel to it
    -energy is concentrated at headlands, dissipated in bays
  • concentrated energy means erosion, lower energy leads to deposition, creating beaches
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36
Q

What is wave reflection?

A

A wave hitting vertical surface such as a cliff face or sea wall bounces back without breaking or losing its energy. The clapotis effect.

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37
Q

What 3 lithological factors effect erosion?

A

Hardness
Composition
Structure

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38
Q

How does rock hardness effect erosion?

A
  • harder rock like granite erodes slowly
  • softer rock like clay have less strength to erode quicker
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39
Q

How does composition of rock affect erosion?

A
  • mineral composition effects the rate of weathering
  • rate of hydrolysis (reactivity to water)
  • whether the substance is soluable in water
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40
Q

How does rock structure affect erosion?

A
  • many joints and bedding planes case weaknesses
  • faults cause major weakness
  • folding in rock creates weakness
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41
Q

What are the 4 sub-aerial processes?

A
  • physical/mechanical weathering
  • chemical weathering
  • biotic weathering
  • mass movement
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42
Q

What are the 4 marine erosional processes?

A

-hydraulic action
- abrasion
- attrition
- solution

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43
Q

What are the 3 physical/mechanical weathering processes?

A

Freeze thaw, salt crystallisation and water-layer weathering.

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44
Q

What is freeze-thaw?

A

Repeated freezing and thawing of water results in the expansion of cracks in rocks, causing small fragments to break off.

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45
Q

What is salt crystallisation?

A

Sea water evaporates from cracks, allowing salt crystals to grow, exerting pressure and causing pieces of rock to break off.

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46
Q

What is water-layer weathering?

A

Constant wetting and drying causes clay-rich rock to expand and contract, resulting in cracks, which aid physical weathering processes.

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47
Q

What are the 6 chemical weathering processes?

A

Solution
Oxidation
Hydration
Hydrolysis
Chelation
Carbonation

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48
Q

What is ‘solution’?

A

The removal of rock dissolved in acidic rain water.

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49
Q

What is oxidation?

A

Oxygen dissolved in water reacts with minerals, causing oxidation.

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50
Q

What is hydration?

A

Minerals in rocks absorb water, which weakens their structre, making them more suseptible to weathering.

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51
Q

What is hydrolysis?

A

Breakdown of rock by acidic water and produces clay and soluble salts, especially feldspar in granite

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52
Q

What is chelation?

A

Organisms produce substances called chelates, which decompose minerals.

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53
Q

What is carbonation?

A

CO2 dissolved in rain water creates weak carbonic acid, which dissolves calcium carbonate in limestone.

54
Q

What are the 2 biotic weathering processes?

A

Plant growth
Animals

55
Q

What are the 6 mass movement processes?

A

Landslide
Rockslide
Rotational slip
Mudslide
Soil creep
Solifluction

56
Q

What is a landslide?

A

Rocks affected by physical weathering or marine erosion collapse downwards

57
Q

WHat is a rockslide?

A

Rocks sliding down a cliff face when the bedding planes dip towards the sea

58
Q

What is a rotational slip?

A

Softer rocks give way, moving downhill in one mass along a concave slip surface

59
Q

WHat is a mudslide?

A

Saturated soft rock (often on top of impermeable rock) flows downhill.

60
Q

What is soil creep?

A

Soil particles move downslope, aided by the raindrop impact.

61
Q

What is solifluction?

A

Movement of wet soil downslope caused when underlying layers are frozen.

62
Q

What is hydraulic action?

A

Breaking waves create hydraulic pressure in joints. Air in cracks in a cliff face can be compressed by the force of waves and then rushes out when the wave retreats. This can weaken the rock.

63
Q

What is abrasion?

A

Rock fragments wear away the coast. Abrasion involves rock praticles being scraped over bare rock, wearing it away.

64
Q

What is attrition?

A

Eroded rocks are worn smaller and rounder by constant rubbing against each other with movement of the sea.

65
Q

What is a cliff profile influenced by?

A

Geology - harder rocks produce steeper cliffs, while softer rocks produce lower angled cliffs.
Structure - bedding planes influences angles of the cliffs

66
Q

What are the 5 stages to the formation of a wave cut platform?

A
  • marine erosion creates a wave cut notch at the cliff base
  • the cliff is undercut, collapses and repeats
  • the cliffs retreat, leaving a gently sloping surface called a wave cut platform
  • a wide wave cut platform prevents marine erosion reaching the cliff foot, reducing rate of erosion
  • sub-aerial processes continue working on the cliff face, reducing the angle of slope
67
Q

What is a disconcordant coastline?

A

Bands of different rock types lie at right angles to the shoreline

68
Q

What is a concordant shoreline?

A

Beds of different rock types lay parallel to the shore line.

69
Q

What is the 4 stage cave arch stack stump sequence?

A
  • marine erosion creates sea caves along a faultline
  • further erosion results in caves either side of a small headland meeting, forming an arch
  • overtime the arch becomes unstable and collapses, leaving an isolated pillar of rock - a stack
  • erosion processes attack the stack, causing it to collapse, leaving a short section called a stump
70
Q

What is the cave, blowhole, geo sequence?

A
  • marine erosion processes create sea caves along a line of weakness
  • waves force air and water into the cave, creating a shaft upwards to the surface and forming a blowhole, where water gushes out in certain tide and wave conditions
  • continued erosion causes the extended cave roof to collapse, leaving a long narrow inlet, a geo. Geos can form along a line of weakness, where erosion processes have greater impact.
71
Q

What are the 4 trasnportational processes

A

Traction
Saltation
Suspension
Solution

72
Q

What is traction?

A

Sediment rolls along the seabed

73
Q

What is saltation?

A

Sediment is bounced along the seabed

74
Q

What is suspension?

A

Small particles are held ad moved in the water

75
Q

What is longshore drift?

A

-Waves approach at an angle due to prevailing winds, swash washes sediment diagonally up the beach
-Gravity pulls backwash with sediment straight down the beach
Repeated action results in the net movement of sediment along the beach parallel to the shoreline.
-The direction is predominantly one way due to the prevailing winds. Changes in wind direction can result in movement in the opposite direction, bringing greater complexity to the landscape.

76
Q

When can coastal deposition occur?

A
  • waves lose velocity after breaking
  • backwash percolates quickly into the beach
  • sheltered coastlines reduce wave energy
  • flocculation
77
Q

What is flocculation?

A

Flocculation occurs where fresh water mixes with sea water, such as in a river estuary. Clay particles coagulate due to chemical reactions to form flocs, which are heavier and more likely to be deposited.

78
Q

What is a swash-aligned beach?

A
  • waves break parallel to the shore
  • sediment moves onshore/offshore
79
Q

What is a drift-aligned beach?

A
  • waves break at an oblique angle to the shore
  • longshore drift along the shore
80
Q

What is a zeta formed beach?

A
  • waves break at an oblique angle but a headland at each end causes wave refraction, blocking sediment movement
  • longshore drift along the coast, but sediment builds up in front of the headland
81
Q

What is a spit?

A

A linear ridge of sediment joined to the land at one end.

82
Q

How do spits form?

A
  • lsd moves sediment along the coast
  • waves hit a headland, material gets deposited horizontal to it
  • sediment can be deposited behind the spit to form mudflats or marshes
  • example christchurch harbor is Dorest
83
Q

How do bars form?

A

A bar forms when a spit grows to form a ridge that blocks off a bay, creating a lagoon between mainland and the bar.
Example is Slapton Sands in Devon

84
Q

What is a tombolo?

A

A tombolo is a spit or bar that joins the mainland to an island, for example the eastern end of chesil beach, where it joins the Isle of Portland

85
Q

What is a cuspate foreland?

A

Triangular shaped projection from the shoreline made up of a series of ridges created by longshore drift from opposing directions. Example Dungeness in Kent.

86
Q

What are aeolian processes?

A

Relate to wind activity and how the wind erodes, transports and deposits sediments.

87
Q

What are the condtions needed for aeoian processes to deposit sediment?

A
  • an abundant supply of sand
  • a shallow beach gradient
  • a tidal range allowing a large area of sand to dry out at low tide
  • prevailing onshore winds
  • an area inland where windblown sand can accumalate
88
Q

What is the 7 stage process regarding the formation of a sand dune?

A
  • constructive waves deposit sediment on the beach
  • wind blows onshore move sand inland by creep and saltation
  • where an obstacle or vegetation reduces wind velocity, the sand is deposited and quickly accumalates
  • plants such as sea couch grass and marram grass become established, increasing sand accumulation and forming an embryo dune
  • continued deposition leads to the embryo dunes forming a ridge
  • new embryo dunes form in front of the ridge, repeating the process
  • gradually the older dunes become covered in vegetation and are stablised
89
Q

What are ridges in sanddunes?

A

Lines of dunes parallel to the coast

90
Q

What are slacks in sand dunes?

A

Hollows found between the dune ridges

91
Q

What is a grey dune?

A

Older dunes where decomposing organic matter creates a humus layer on the surface, making the dunes appear grey

92
Q

What is a yellow dune?

A

Younger dunes with no humus layer

93
Q

What are embryo dunes?

A

youngest dunes in the earlier stages of formation

94
Q

What are fore dunes?

A

Dunes closest to the sea

95
Q

What are fixed dunes?

A

Older dunes stabilised with vegetation, which are unlikely to change

96
Q

What is a blow-out in sanddunes?

A

An area of dune that has been eroded by the wind, often due to its protective cover of vegetation being removed by animal or human activity

97
Q

How are tidal flats formed?

A
  • edges of estuaries are sheltered and so are low energy coastlines
  • deposition of fine sediment is the main process creating a tidal mudflat
  • at low tide the mudflat is uncovered, fresh water from tributaries flows across the mudflat to the sea in small channels called rills.
  • example morecambe bay
98
Q

What is a rill?

A

Shallow channels cut by the action of running water.

99
Q

What are salt marshes?

A
  • gently sloping, vegetated areas of intertidal mudflats
  • found in low energy, sheltered locations such as estuaries, lagoons and behind spits
100
Q

What are coral reefs?

A

Coral reefs are calcium carbonate structures secreted by tiny animals called polyps. They build slowly overtime and can be hundreds of meters thick.

101
Q

What are the ideal conditions for coral growth?

A
  • clear water, allowing light penetration
  • seawater temperatures 23-29*c
  • shallow water - less than 100 metres deep
  • wave activity, which aerates the water
102
Q

where are most coral reefs located?

A

91% of all coral reefs are found in the indo-pacific region. The great barrier reef is the largest, with over 2900 individual reefs

103
Q

What happens if the coral conditions change?

A

Changes in conditions can kill coral, making it susceptible to erosion. Broken coral can be transported and deposited to make rubble mounds suitable for new coral colonisation.

104
Q

What can mangroves form?

A

they can form an ecosystem of small trees growing along tropical coastlines where fine sediments have been deposited
the vegetation is adapted to be salt tolerant and able to survive in waterlogged mud with extremes of temperatures

105
Q

What is an adapatation of mangroves?

A

Stilt roots, roots that grow upwards from the mud to allow oxygen uptake and the ability to absorb air through the bark

106
Q

What can mangroves encourage?

A

They encourage further deposition and protect coastlines from erosion by reducing wave energy, which can be a method of reducing the impacts of tsunamis.

107
Q

What can tsunamis or storm events cause?

A
  • removing large amounts of beach sediment, changing the profile or removing it altogether
  • destruction or breaching of sand dunes
  • coastal flooding
108
Q

What is meant by rapid mass movement?

A

Sudden rockfalls, landslides and slumps create changes in cliff-face profiles and retreating cliffs, with loss of land and possibly buildings.

109
Q

How does the summer influence a beach profile?

A
  • fewer storms
  • less frequent high wind speeds
  • lower energy waves
  • waves predominantly constructive
  • sediment moved onshore, building up the beach, increasing the gradient of the upper beach and forming a berm
110
Q

How does the winter influence a beach profile?

A
  • more storms
  • high winds more frequent
  • higher energy waves
  • destructive waves more frequent
  • sediment moved offshore, lowering the beach profile, creating a steeper upper beach and a gentle lower beach
111
Q

What are the 2 types of sea level change?

A

Eustatic and isostatic change

112
Q

What is meant by eustatic sea level change?

A
  • a global change in the volume of water in the oceans
  • during a glaciation period more water is frozen, resulting in less liquid in the oceans, so sea level falls
  • global warming of the climate increases melting of continental ice sheets, adding water to the oceans and raising sea level
  • warming of the oceans results in the volume of water expanding, creating a rise in sea level
113
Q

What is meant by isostatic sea level change?

A
  • a localised change in the relative sea level caused by the upward or downward movement of land masses
  • during glacial periods the weight of ice causes the land to sink into the crust, making sea levels appear relatively higher
  • melting ice removes the weight and the land very slowly rises (isostatic recovery), causing a relative fall in sea level
114
Q

How does rising sea levels effect landforms?

A
  • flooding of lower lying parts of the coast
  • deltas, spits and beaches disappear underwater or due to increased rates of erosion
  • river floodplains and valleys flood to form a broad river estuary called a ria.
115
Q

How does falling sea levels effect landforms?

A
  • beaches are no longer affected by the waves and are left stranded above sea level, forming raised beaches
  • vegetation can grow and cause stability
  • wave cut platforms can form a marine terrace which can be used for agriculture
116
Q

Why are costal zones important for human activities?

A
  • recreation and tourism
  • residential
  • job opportunities
  • agriculture
  • industry
    transportation
117
Q

Why are tourists attracted to coastal zones?

A
  • natural features
  • deep water ports for cruise ships
  • rebranding and marketing by coastal resorts
  • visit filming locations
118
Q

What affects can tourism at a coastal zone cause?

A
  • development of services
  • negative impacts on the environment
  • infrastructure overload and overheating
  • increase in second homes
  • seasonal dependencies for business
  • socio-economic cultural changes
  • vulnerability of reliance on tourism economic activity
  • large number of jobs creates
  • multiplier effect is created
119
Q

What are the negative impacts of coastal processes on human activity?

A
  • rapid mass movement events
  • coastal erosion
  • loss of beach sediment
  • erosion of vulnerable ecosystems
  • low lying areas viable to flooding
  • increases deposition at ports and harbours
120
Q

What are the 5 management strategies for coastal management?

A
  • do nothing
  • managed retreat or realignment
  • hold the line
  • advance the line
  • limited intervention
121
Q

What is meant by doing nothing as coastal management?

A

Allows natural processes such as coastal erosion to continue

122
Q

What is meant by managed retreat or realignment as coastal management?

A

Allows the shoreline to move inland by erosion or flooding to a new line of defence

123
Q

What is meant by advancing the line as coastal management?

A

The shoreline is moved seawards either by using hard engineering strategies or sand dune growth

124
Q

What is meant by holding the line as coastal management?

A

The present shoreline is protected either by using hard or soft engineering strategies

125
Q

What is meant by llimited intervention as coastal management?

A

Deals with the problem to some extent, it can involve raising buildings to cope with flooding ect

126
Q

What does the choice of coastal management strategy depend on?

A
  • feasibility
  • cost-benefit analysis
  • environmental impact analysis
  • risk assessment
127
Q

Name some hard engineering strategies.

A
  • sea walls
  • rock armour
  • revetments
  • gabion cages
  • groynes
  • draignage
  • offshore bars
  • rock bund
128
Q

Name some soft engineering strategies.

A
  • beach nourishment
  • beach reprofiling
  • beach recycling
  • fencing/hedging
  • replanting vegetation
  • cliff profiling
129
Q

What are the 3 main conservation charities?

A

World heritage
National marine reserves
Sites of Special Scientific Interest (SSSI)

130
Q

What is offshore dredging?

A

The extraction of sand and gravel from the seabed for use in contruction, especially of sea defences.

131
Q

What are the negative effects of offshore dredging?

A
  • destruction of habitat and changes to the marine food web
  • changes to wave types and sediment flows, resulting in changes in the beach profile, whcich can increase the rate of erosion if waves travel further up the beach.

AS Geography (8 decks)

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