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A Level geography > Coasts > Flashcards

Coasts Flashcards

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1
Q

What System is a coast?

A

Open System

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2
Q

Sediment cells

A

. Coasts split into sections, often bordered by prominent headlands

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3
Q

Dynamic equilibrium

A

The balance of inputs and outputs in a natural system

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4
Q

Dynamic equilibrium in a sediment cell

A

Where inputs and outputs are in a constant state of change but remain in balance

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5
Q

Dynamic equilibrium :longterm and short term

A

. Can be interrupted by human intervention ( hard engineering)- long term
. Can be interrupted by natural variations - short term

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6
Q

Inputs

A

Matter and energy entering the system from outside sources

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7
Q

Inputs examples

A

. Marine- waves and tides
. Atmosphere- sun, air pressure, wind speed and direction
. Humans- pollution, Defences

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8
Q

Outputs

A

Matters and energy moving from the system to outside sources

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9
Q

Outputs example (4)

A

. Ocean currents
. Rip tides
. Sediment transfer
. Evaporation

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10
Q

Stores/ sinks examples (6)

A

. Beaches
. Sand dunes
. Spits
. Bars
. Headlands and Bays
. Wave cute platform
Etc

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11
Q

Stores/ sinks

A

Individual elements of part of a system

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12
Q

Transfer/flows

A

the relationship between inputs, outputs and stores in a system

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13
Q

Flows/ transfers (5)

A

. Transportation
. Mass movement
. Weathering
. Erosion
. Deposition

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14
Q

Energy

A

driving force in a system

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15
Q

Energy examples

A

Wind
Waves
Tides
Currents

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16
Q

Positive feedback

A

The system becomes more unstable as it increases/ speeds up

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17
Q

Negative feedback

A

The system becomes more stable as it decreases/ slows down

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18
Q

Constructive waves (6)

A

. Strong Swash
. Weak Backwash
. Long wave length
. Low frequency ( 6-8 waves per minute)
. Flat and low
. Causing deposition

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19
Q

Destructive waves (6)

A

. Large height
. Short wavelength
. Strong backwash
. Weak swash
. High frequency( 13-15 waves per Minute)
. Causing erosion

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20
Q

Sediment budget

A

. The use of inputs, outputs ,stores and transfers to asses the gains and losses of sediment within a sediment cell

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21
Q

Tides

A

. The changes of sea levels due to gravitational effects from moon and the sun

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22
Q

Tidal ranges

A

The upper and lower limits of erosion and deposition ( the difference between high tide and low tide)

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23
Q

Tidal surges

A

Narrow neck of water, tides can be funnelled and increase in height and range

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24
Q

Highest high tide and lowest low tide3s

A

. when the sun and moon are in alignment, so gravitational forces work with each other - spring tides

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25
Q

Highest low tides and lowest high tides

A

. when the sun and the moon are perpendicular to each other so gravitational forces work against each other -neap tides

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26
Q

Currents

A

The seasonal movement of water in the seas and oceans

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27
Q

High energy coastlines (4)

A

. Strong steady prevailing winds, creating high energy waves
. Rate of erosion> Tate of deposition
. Typical landforms: headlands, cliffs and wave cut platforms
. Eg north Cornish coast

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28
Q

Low energy coasts (4)

A

. Coastlines where wave energy is low
. Rate of deposition > Rate of erosion
. Typical landforms: beaches and spits
. Eg the Baltic Sea

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29
Q

Backshore

A

Is the area lying between the high water mark and the landward limit of marine activity

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30
Q

Foreshore

A

Area lying between high water mark and low water mark

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31
Q

Inshore

A

Area between the low water mark and the point where waves have no influence on the land beneath them

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32
Q

Offshore

A

Area beyond the the point where waves impact the sea bed

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33
Q

Wave refraction (6)

A

. Waves refract onto the headland
. The waves become higher, steeper with shorter wave length
. High energy waves concentrated on the headland, increasing erosion
. Waves refract out onto bay
. Waves in the deep water are still moving forward so the waves bend
. Low energy waves concentrated in the bays, increasing deposition

34
Q

Longshore drift (3)
( littoral drift)

A

. Prevailing wind approaching the beach at an angle
. Sediment is dropped back out to sea
. Picked up by the prevailing wind and pushed back up the beach before it’s then dragged back out to sea

35
Q

. Rip currents (3)

A

. Strong currents moving away from the shoreline
. Sea water is piled along the coastline by incoming waves
. Current runs parallel to coast before flowing to breaker zone, at a headland

36
Q

Sub-aerial processes (2)

A

. Weathering
. Mass movement

37
Q

Marine processes ( 3)

A

. Erosion
. Deposition
. Transportation

38
Q

Simple spits

A

. Longshore drift deposits sand and shingle across the river mouth, leaving a bank of sand and shingle sticking out to sea ( a straight spit that grows out roughly parallel to the coast is called a simple spit )

39
Q

Compound spit

A

. Changes in wind direction lead to curved end
. This can happen multiple times creating multiple recurved ends

40
Q

A bar

A

Formed where a spit grows across a bay. Behind the bar forms a lagoon where water is trapped. Over time the lagoon will be filled up with Silt and may gradually form salt marshes

41
Q

Mudflats

A

. Found at the edge if the permanently submerged marine zones

42
Q

Eustatic change

A

When sea level itself rises or falls (global)

43
Q

Isostatic change

A

When land rises or falls relative to the sea (local )

44
Q

What causes eustatic change?

A

. An increase in temperature causing melting ice sheets, which increases sea level
. A decrease in temperature causing more precipitation to fall as snow. This increases the volume of water stores in glaciers and so reduces the volume of the sea, decreasing sea level
. Changes in earth’s tectonic movement alters the earths shape and volume of ocean basin e.g sea floor spreading increases the volume of basin so decreases sea level

45
Q

What causes Isostatic change ?

A

. Slow uplift of land can continue for thousands of years after the weight of retreating glacier has gone
. Subsidence of land due to shrinkage after abstraction of ground water e.g drainage of marshland
. tectonic crustal processes: one plate is forced beneath another at a plate margin

46
Q

Submergent coastlines

A

Stretches along the coast have been inundated by the sea due to eustatic changes

47
Q

Emergent coastlines

A

Stretches along the coast have been exposed by the sea due to Isostatic changes

48
Q

Submergent landforms

A

. Rias
. Fjords
. Dalmatian coastlines

49
Q

Emergent landforms

A

. Raised beaches
. Marine platforms

50
Q

Land slides (6)

A

. Shifting material downhill due to gravity

. In coastal areas, cliffs are undercut by wave action which causes an unsupported overhang and collapses

. Slides- material shifts in a straight line
. Slumping- material shifts with rotation

. Unconsolidated rocks are prone to collapse as there is little friction

. Runoff can erode fine particles and transport them downslope

51
Q

Mudflows (4)

A

. Water gets trapped in rocks, increasing water pressure which forces rock particles apart and leads to slope failure

. Unconsolidated rock is prone to collapse due to little friction

. Heavy rainfall can saturate Unconsolidated rock, further reducing friction and making it more likely to collapse

. Runoff can erode fine particles and transport them downslope

52
Q

Mechanical Weathering (3)

A

Freeze thaw-
.water enters cracks in the rocks which the freezes (temp below 0 degrees)
. the water expands by almost 10% meaning ice occupies more space and so exerts pressure surrounding the rock
. As process repeats, the crack widens, breaking the rock

53
Q

Biological weathering

A

breakdown of rocks by the Action of vegetation and coastal organisms
. marine organism such as piddocks (a shell fish ), have specifically adapted shells that enable them to drill into solid rock

54
Q

Chemical weathering

A

Carbonation
. When carbon dioxide dissolves in rainwater makes a weak carbonic acid. This reaction with calcium carbonate in rocks like limestone and chalk creates calcium b carbonate, which dissolves easily in water

55
Q

Littoral zone

A

Area of land between the cliffs or dunes and offshore area beyond the limit of the waves

56
Q

Wave formation (4)

A

. Winds move across surface of the water
Causing frictional drag ( ripples and waves are created)

. the sea bed becomes shallower towards the coastline and orbit of water particles becomes more elliptical, leading to horizontal movement of the waves

. The wave height increases but the wave length and wave velocity decreases

. This causes water to back up behind the wave until wave breaks and surges up the beach

57
Q

Factors effecting wave energy

A

. Strength of wind- the larger the pressure between two areas, the stronger the wind

. Duration of wind- if wind is active for longer periods of time, then the energy of the waves build up and increase

.Size of Fetch- the larger the distance over the wind blows the more powerful the waves will be

58
Q

Types of waves in a coastal environment

A

. Constructive waves dominate but destructive waves dominate in winter

. Constructive waves may become destructive waves if a storm begins

. Climate change may increase storm frequency within the UK

. Coastal management may affect the type of waves that occur

59
Q

Negative feedback ( beaches and waves)

A

. constructive waves causes deposition on the beach, which leads to the beach profile becoming steeper

. Steeper beaches favour the formation of destructive waves, which are then more likely to occur

. Destructive waves erode the beach, reducing the beach profile and leading to the formation of constructive waves

. Constructive waves occur more frequently in the summer, meaning that beach profile is more gentle and steeper durning the winter where destructive waves are more common

60
Q

Négative feedback

A

. Due to different rock strengths, erosion leads to the formation of headlands, where resistant rock exists and bays where unconsolidated rocks and clays are dominant

. This increases the forces of erosion in headlands and reduced erosion in bays.

. Headlands are worn away which again increases erosion within the bays

61
Q

Wave Quarrying

A

When breaking waves hit the cliff face to directly pull away rocks or remove smaller weathered fragments

62
Q

Factors effecting erosion

A

. Waves
. Beach size
. Activity of sub aerial processes

63
Q

Rock armour ( hard engineering)

A

. Coast effective - P
. Rocks are sourced from elsewhere so do not fit with the local geology- N
. A hazard if climbed upon- N

64
Q

Marsh Creation ( soft engineering)

A

. Created and important wild life habitat- P
. Farmers lose land and may need to compensate as a result- N

65
Q

Sea walls

A

. Effective erosion prevention- P
. Promenades has tourism benefits-P
. Visually unappealing- N
. Expensive to construct

66
Q

Integrated coastal zone management ( ICZM)

A

. ICZM recognises that coastal management must be sustainable

. Involves all stakeholders and plans for the long term

. In 2013, the EU adopted a new initiative which promotes the use of ICZM

67
Q

Shoreline management Plans (SMP’s)

A

. Hold the line- defences used to maintain the current position of the shoreline
. Managed retreat- engineering techniques are used to allow the coastline to advance inland and create its own natural defences

. Advance the line- defence are built to try and move the shoreline seawards

. No active intervention- the shoreline is exposed to natural processes

68
Q

Rias

A

When rising sea levels flood narrow inlets and river valleys. They are deeper at the mouth of the inlet, with the water depth decreasing further inland

69
Q

Fjords

A

when rising sea levels flood deep glacial valleys to create natural inlets and harbours eg in New Zealand
very straight and narrow and has very steep sides

70
Q

Dalmatian coasts

A

when valleys running parallel to the coast become flooded as a result of sea level changes, eg Croatia

71
Q

how does tidal Range link to sub-aerial weathering?

A

Determining spatial limits and the length of time the littoral zone is exposed to sub aerial weathering

72
Q

Wave cut platform ( 4)

A

. Sea erodes the land so cliff retreats due to action of waves and weathering

. This forms a wave cut notch at the high water mark which eventually develops into a cave

. Rock above becomes unstable and collapses

. Wave cut platform is
formed

73
Q

Headlands and bays (2)

A

. Bands of hard rock and soft rock at right angles to the shoreline

. Soft rock erodes quickly forming a bay, the hard rock erodes slowly and sticks out as a headland.

74
Q

Spits (5)

A

. Spits are formed when the coast suddenly changes direction

. Longshore drift continues to deposit material across the river mouth leaving a bank of sand and shingle

. A straight spit that grows parallel to the coast is called a simple spit

. Changes in dominant wind and wave direction may lead to spit having curved end ( recurved end). Over time this can create compound spits

. The area behind this develops into mudflats and saltmarshes

75
Q

Offshore bars and tombolos (4)

A

. Spit joins two headlands together and a bar is formed

. A lagoon forms behind the bar

. Some bars form off the coast when material moves towards the coast( at sea level rise)- offshore bars

. Bar connects the shore to an island is called tombolo e.g St Ninian’s Isle

76
Q

Sand dunes (4)

A

. Sand deposited by littoral drift

. Sand trapped by berms is colonised by plants and grasses.

. The vegetation stabilises the sand and encourages more sand to accumulate forming embryo dunes

. Over time, older dunes move inland- mature dunes can reach 10m in height

77
Q

Estuarine Mudflats and salt marshes (3)

A

. Silt and mud are deposited by the river tide- mudflats develop

. Mudflats colonised by vegetation that survived high salt levels and long periods of submergence by tides

. Plants trap mud and silt creating exposed salt marshes between tides

78
Q

Barrier Islands/ beaches (5)

A

. Sand runs parallel to the shore that is detached.

. Form in areas with large amount of sediment, gentle slopes offshore, powerful waves and small tidal ranges

. Not clear how it is formed but scientists say it was formed after last ice age which caused rapid sea level rise.

. Another theory is that islands where originally bars attached to the coast which is eroded into sections causing beaches.

. Lagoon formed behind barrier island eg in Horn Island in Mississippi, east coast of USA

79
Q

Raised beaches

A

. the fall of sea level leaves beaches above high tide mark

. sea level fall exposes wavecut platforms, leaving them raised above their former level

. The cliffs above the raised beaches are no longer eroded by the sea, so they are slowly covered by vegetation ( relict cliffs)

. these raised features are degraded overtime

80
Q

sea level change

A

. around 20,000 years ago, sea levels have been rising

.sea levels have increased in about 235mm

A Level geography (38 decks)

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