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A level physical geography > the coastal system > Flashcards

the coastal system Flashcards

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1
Q

What kind of system is the coastal system?

A

open as it receives inputs from outside the system and transfers outputs away from the system and into other systems

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2
Q

What kind of system are sediment cells

A

They are closed systems as sediment is recycled within the sediment cell

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3
Q

What are the sources of energy in a coastal system?

A

wind
waves
tides
currents

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4
Q

what are the different types of waves

A

constructive
destructive

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5
Q

what is the effect of wind on waves

A

A high wind speed and long fetch creates higher and more powerful waves

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6
Q

What are the differences between constructive and destructive waves

A

Constructive waves have a powerful swash and weak backwash
constructive waves have a low frequency
constructive waves are low and long
constructive waves carry material up the beach and deposit it

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7
Q

Describe the action of tides

A

Tides are the periodic rise and fall of the ocean surface caused by the gravitational pull of the moon and sun
Tides affect the position at which waves break on the beach - at high tide they break higher up the shore
The land between maximum high and low tide is where most landforms are created and destroyed

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8
Q

Describe the action of currents

A

A current is the general flow of water in one direction and can be caused by wind or by variations in water temperature and salinity

currents cause material to move along the coast

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9
Q

define sediment budget

A

The difference between the amount of sand that enters and leaves the system

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10
Q

How does the sediment budget affect the coastline

A

A positive sediment budget means more sediment enters than leaves the cell and overall, the coastline builds outwards

if the sediment budget is negative then the coastline retreats

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11
Q

How many sediment cells are there in the UK

A

11

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12
Q

what are the four types of erosion

A

abrasion
attrition
hydraulic action
solution

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13
Q

what are the four types of transportation

A

traction
saltation
suspension
solution

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14
Q

what is the difference between marine and aeolian deposition

A

Aeolian deposition is when sediment carried by wind is deposited and marine is when sediment carried by seawater is deposited

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15
Q

what are the 4 types of sub-aerial weathering

A

salt weathering
freeze-thaw weathering
chemical weathering
biological weathering

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16
Q

What are the 4 types of mass movement

A

slumping - material shifts with rotation
sliding - material shifts in a straight line
rockfall
mudflow

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17
Q

describe how cliffs and wave-cut platforms are formed

A

weathering and wave erosion causes a wave-cut notch to form at the high watermark and this eventually develops into a cave

the rock above the cave becomes unstable and with nothing to support it collapses

wave cut platforms are flat surfaces left behind when a cliff is eroded

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18
Q

describe how headlands and bays are formed

A

headlands and bays form when there are alternating bands of soft rock, and the soft rock is eroded quickly forming bays and the hard rock left over forms a headland

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19
Q

describe the formation of caves, arches, stacks and stumps

A

weak areas in rock are eroded to form caves and when caves on opposite sides join to form an arch

the arch continues to experience erosion and weathering and may collapse to form a stack

erosion of the stack will lead to a stump

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20
Q

Give an example of a stack

A

Loch Bracadale, Scotland

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21
Q

what are the erosional coastal landforms

A

cliffs and wave cut platforms
caves, arches, stacks, stumps
headlands and bays

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22
Q

Describe how a beach is formed

A

beaches form when constructive waves deposit sediment on the shore and they are a store in the coastal system

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23
Q

What is the difference between swash and drift aligned beaches

A

swash aligned beaches may have larger sediment and there is limited longshore drift, so sediment doesn’t travel far along the beach

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24
Q

what are some distinctive features of beaches

A

berms
cusps
runnells
larger sediment is found towards the top of the beach

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25
Q

what are berms

A

ridges of sand and pebbles found at high tide marks

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26
Q

what are runnels

A

grooves in the sand running parallel to the shore formed by backwash draining to the sea

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27
Q

what are cusps

A

small, curved dips in the beach where the swash comes in

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28
Q

what is a spit and how are they formed

A

they are a long, narrow strip of land which is formed when the coast suddenly changes direction and littoral drift causes the beach to extend to the sea and a salt marsh may form bhind the spit due to the sheltered environment

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29
Q

What is the difference between a simple and a compound spit

A

straight spits are simple
Compound spits may have many recurved ends due to several periods of growth

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30
Q

Describe the difference between offshore bars and tombolos

A

bars are formed when a spit joins two headlands and a lagoon is formed behind it. A tombolo however, is when a spit joins to an island

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31
Q

describe barrier islands

A

they are long, narrow islands of sand or gravel that run parallel to the shore and are detached from it. They tend to form in areas where there’s a good supply of sediment, fairly powerful waves and a small tidal range

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32
Q

describe the formation of barrier islands

A

it is not exactly clear how they form but scientists believe they probably formed after the last ice age ended when ice melt cause rapid sea level rise. The rising waters flooded the land behind beaches and transported sand offshore where it was deposited in shallow water forming islands

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33
Q

Describe the formation of sand dunes

A

sand dunes are formed when sand deposited by littoral drift is moved up the beach by the winds
Sand trapped by driftwood or berms is colonised by plants and grasses stabilising the sand dune encouraging more sand to accumulate forming embryo dunes

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34
Q

What kind of sere is a sand dune

A

psamosere

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35
Q

What is a plagioclimax

A

when a climatic climax isn’t reached due to human intervention such as a golf course

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36
Q

What are sand dunes an example of

A

Succesion

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37
Q

Describe the formation of mudflats and salt marshes

A

mudflats and saltmarshes form in low energy, sheltered environments e.g., behind spits
as silt and mud are deposited by the river or tide mudflats develop and are colonised by vegetation that can survive halophytic conditions and long periods of submergence by the tide
the plants trap more silt and sediment and gradually the mudflat builds upwards to create an area of saltmarsh that remains exposed for longer and longer between tides

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38
Q

Give 6 examples of depositional landforms

A

beaches
spits
tombolos and bars
barrier island
mudflats and saltmarshes
sand dunes

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39
Q

define eustatic change

A

when the sea level itself rises or falls

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40
Q

deine iostatic change

A

when the land rises or falls relative tothe sea

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41
Q

Describe how eustatic change occurs

A

glacial melting or thermal expansion

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42
Q

describe how isostatic change occurs

A

isostatic recovery - when glacial ice melts and the land lifts to readjust due to the reduced weight of the ice on the land

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43
Q

What is the difference between isostatic and eustatic change

A

eustatic is global and is the change in water
isostatic change occurs locally and is the change in the land relative to the sea

44
Q

give evidence of sea level change

A

global sea level is rising by around 2mm each year
increasing temperatures are likely to cause increases in sea level and sea level is predicted to rise by 8-16mm per year by 2100

45
Q

How can eustatic change impact coastlines

A

submergence of low lying islands
changes in coastlines - 8000km2 of Bangladesh will be lost
increased coatal erosion

46
Q

give examples of emergent coastlines

A

raised beaches
sea-level fall can lead to exposed wave-cut platforms
relict cliffs- cliffs above raised beaches are no longer eroded by the sea

47
Q

Give examples of submergent coastlines

A

Rias - flooded river valley e.g., Milford Haven in Wales
Fjords - drowned glacial valleys
Dalmation coasts- valleys are flooded leaving islands parallel to the cast e.g., Croatio

48
Q

What is the difference between rias and fjords

A

Rias are flooded river valleys whereas fjords are drowned glacial valleys
Rias generally have a long and wide cross profile whereas fjords are narrow and straight sided
Rias become shallower inland but fjords are very deep inland

49
Q

what are the 4 options for coastal management

A

hold the line
advance the line
do nothing
managed retreat

50
Q

define hold the line

A

maintain the existing coastal defences

51
Q

define advance the line

A

build new coastal defences further out to sea

52
Q

define managed realignment

A

allow the shoreline to move but manage the retreat so it causes the least damage

53
Q

what is the difference between hard and soft engineering

A

Hard engineering involves built structures whereas soft engineering involves coaxing natural processes along

54
Q

describe how a sea wall works

A

the wall reflects waves back out to sea preventing erosion of the cast and flooding

55
Q

What are the disadvantages of sea walls

A

they are expensive to build and maintain and create a strong backwash which erodes the under wall

56
Q

describe how a revetment works

A

they are slanted structures built at the foot of a cliff and absorb wave energy preventing cliff erosion is relatively cheap to maintain

57
Q

what are the disadvantages of revetments

A

expensive to build and creates a strong backwash

58
Q

Describe how gabions work

A

gabions are rock-filled cages which absorb energy and are quite cheap

59
Q

What are the disadvantages of gabions

A

ugly

60
Q

describe how ripraps work

A

they are boulders piled up along the coast which absorb wave energy and are fairly cheap

61
Q

What are the disadvantages of rip raps

A

they can shift in storms

62
Q

Describe how groynes work

A

groynes are fences built at right angles to the coast and traps material deposited by littoral drift creating wider beaches and gives greater protection from floods and erosion and they are quite cheap

63
Q

what are the disadvantages of groynes

A

they deplete further along the beach of sediment making it more prone to erosion and flooding

64
Q

describe how breakwaters work

A

concrete blocks or builders deposited of the coast forcing waves to break offshore so theyre erosional power is less when they reach the beach

65
Q

What are the disadvantages of breakwaters

A

they are expensive and can be damaged in storms

66
Q

describe how earth banks work

A

They are mounds of earth that act as a barrier against flooding

67
Q

What are the disadvantages of earth banks

A

expensive and can be eroded

68
Q

Describe how tidal barriers work

A

Built across river estuaries and contain floodgates that can be raised to prevent flooding from storm surges

69
Q

What are the disadvantages of tidal barriers

A

theyre very expensive

70
Q

Describe how tidal barrages work

A

dams built across river estuaries and thier main purpose is to generate electricity and water is trapped behind it at high tide
prevent flooding at storm surges

71
Q

What are the disadvantages of tidal barrages(dams)

A

very expensive and can disrupt sediment flow

72
Q

what are the 6 soft engineering defences

A

beach nourishment
beach stabilisation
dune regeneration
land use management
creating marshland
coastal realignment - allowing the sea to flood the land and breaching the defence

73
Q

Define SMP

A

shoreline management plan
the coastline is split into stretches by sediment cells and for each cell a plan is devised for how to manage different areas with the aim of protecting important sites without causing problems elsewhere

74
Q

Define ICZM

A

Integrated coastal zone management
considers all elements of the coastal system such as economy water and people
it is a dynamic strategy
the environment is viewed as a whole and different uses are considered and levels of authority have an input to the plan

It aims to protect the coastal zone in a relatively natural state whilst allowing people to use it and develop it in different ways

75
Q

.what are the different types of wind action

A

surface creep wind rolls or slides sand along the surface

saltation - where wind is strong enough to temporarily lift grains into the airflow to heights of up to one metre for long distances

76
Q

what are some examples of chemical weathering

A

solution
hydrolysis
carbonation
acid rain

77
Q

what kind of waves do bays experience and why

A

they experience low -energy waves that allow sediment to accumulate because of refraction

78
Q

what happens when waves are refracted

A

they become increasingly parallel to the coastline

79
Q

What are the different types of current

A

longshore
rip currents
upwelling

80
Q

what do tidal ranges determine

A

the upper and lower limits of erosion

81
Q

what is the difference between a spring and a neap tide

A

spring tides are the highest and sun, moon and earth are in a straight line

neap tides are 10-30 per cent lower than average and moon is perpendicular to earth and sun

82
Q

what are the main inputs at a discordant coast

A

geology and lithology of the coast

nature of waves approaching the coast

direction and strength of prevailing wind

83
Q

what are the processes at a discordant coast

A

differential rates of erosion at the coast
wave refraction
deposition in the bay
erosion of the headland

84
Q

what are the outputs at a discordant coast

A

the headland and bay
erosional features of the headland
depositional features in the bay

85
Q

why is the size of a wave-cut platform limited

A

as the platform continues to grow the waves break further out at sea and have to travel across more platform before reaching the cliff line so there is a greater dissipation of energy

86
Q

what is a geo

A

the sea will cut inland along a joint widening the crack to form a narrow steep sided inlet

87
Q

why is shingle usually at the top of the beach

A

because water rapidly percolates through shingle so the backwash is somewhat limited in its ability to transport material back down the beach

88
Q

at what kinds of coasts are swash-alligned beaches found

A

irregular coastlines where littoral drift is impeded

89
Q

At what kinds of coasts are drift-alligned beaches found

A

where coastline is fairly regular or where wave direction is at an angle to the beach

90
Q

What can occur as a spit matures

A

sand dunes can develop as deposited sand dries out and is blown landward side of the spit

91
Q

What is the formation of a barrier beach thought to be

A

breaching of a spit or by constructive waves pushing a bar towards land

92
Q

what are some factors that over time have helped to develop the coastline

A

local tectonic processes
sea level change
climatic change
changing ocean currents and wave regimens
human activity
natural disasters

93
Q

what are some inputs of a coastal sand dune

A

plentiful supply of sand
strong onshore winds
large tidal range
obstacle to trap the sand
vegetation growth to encourage further dune growth

94
Q

describe how an embryo dune is formed

A

sand is moved inland mainly by saltation and where there is a large tidal range large amounts of sand are exposed at low tides

sand may be trapped by obstacles such as seaweed and driftwood at the back of the beach possibly on the highest berm

95
Q

Why are embryo dunes suitable for colonisation

A

accumulating wind blown sand is stabilised by grasses and low hummocky dunes are formed and the presence of plants adds organic matter increasing water retention

96
Q

how are foredunes formed

A

upwards growth of embryo dunes raises the height of the dune so they are beyond the reach of all but the highest storm tides

foredunes are originally yellow because they lack organic matter but as vegetation cover increases humus is added to the sand and they look grey in colour

97
Q

What are dune slacks

A

depressions within fixed dunes where water table is on or near the surface

98
Q

why are salt marshes not a permanent feature

A

changes in sea level
wave action
changes in discharge levels in river
changes to tidal flows

99
Q

describe the flows of water at a salt marsh

A

salt water from slow moving sea currents bring large amounts of fine sediments and meets the river which is also carrying its own fine silts and clays

as two flows meet fine particles settle out of the suspension by flocculation where clay particles aggregate to form larger heavier particles that sink to the bed

100
Q

what are the pioneer plants in a salt marsh

A

glasswort, sea-bite, spartina

101
Q

when are raised beaches formed

A

when isostatic movement is faster then eustatic

102
Q

how do dalmatian coasts differ from rias and fjords

A

the flooded valleys run parallel to the coast rather than at right-angles

103
Q

what are changes in sea level a result of

A

increased volume of ocean
subsidence of coast

104
Q

how does rock strata influence coastlines

A

steepest cliffs tend to form in rocks that have horizontal strata or dip gently inland

whereas rocks that dip towards the coast produce more sloping features

105
Q

how can run off impact coastlines

A

may take in the form of a stream emerging in a bay and taking large quantities of load during times of flood

stream cascading over cliff excavating v shaped groove

presence will also assist with many mass movements

A level physical geography (3 decks)

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