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A level GEO > Coasts > Flashcards

Coasts Flashcards

1
Q

Littoral zone

A

The wider coastal zone including adjacent land areas and shallow parts of the sea just offshore

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2
Q

Primary coasts

A

Dominated by land based processes such as deposition from rivers or new land from lava flows

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3
Q

Secondary coasts

A

Dominated by marine erosion or deposition processes from the sea

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4
Q

Emergent coasts

A

Where the coasts are rising relative to sea level eg due to tectonic uplift

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5
Q

Submergent coasts

A

Where coasts are being flooded by the sea either due to rising sea levels or subsiding land

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6
Q

Low energy coastlines

A

Sheltered coasts with limited fetch and low wind speeds resulting in small waves

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7
Q

High energy coastlines

A

Exposed coasts facing prevailing winds with long wave fetches resulting in powerful waves

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8
Q

Cliff profile

A

The height and angle of a cliff face as well as it’s features such as wave cut notches or changes in slope angle

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9
Q

Dynamic equilibrium

A

The balanced state of a system when inputs and outputs balance over time

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10
Q

Short term factors showing the littoral zone is constantly changing

A

Individual waves
Daily tides
Seasonal storms

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11
Q

Long term factors showing the littoral zone is constantly changing

A

Changes to sea level
Climate change

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12
Q

3 features of a marine erosion dominated cliff

A

Steep face
Active undercutting
Limited cliff base debris

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13
Q

3 features of a sub-aerial process dominated cliff

A

Curved slope profile
Lower angle face
Accumulated debris

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14
Q

Faults

A

Major fractures that have moved rocks from their original positions

Formed when the pressure to which a rock is subjected exceeds its internal strength causing it to fracture

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15
Q

Deformation

A

Folds and dips caused by tectonic activity

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16
Q

Strata

A

Different layers with bedding planes

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17
Q

Joints

A

Fractures caused either by contraction as sediments dry out or by earth movements during uplift

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18
Q

Concordant coastline

A

Rock strata run parallel to the coastline

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19
Q

Discordant coastline

A

Different rock strata run at right angles to the coastline
Bands of more and less resistant rock
Headlands and bays

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20
Q

Deposition

A

The laying down of sediment carried by wind or water

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21
Q

Coastal erosion

A

The process in which cliffs are worn away and transported by the sea

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22
Q

Traction

A

Large materials such as boulders are rolled along the sea bed
As they are heavy so waves don’t have enough energy to carry them

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23
Q

Saltation

A

Pebbles or small stones are lifted by the sea but dropped when energy is lost.
As a result pebbles are bounced along sea bed

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24
Q

Suspension

A

Smaller particles such as sand float in the sea

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25
Q

Solution

A

Particles such as clay are dissolved in the sea and constantly move with water

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26
Q

Abrasion

A

Material is hurled against the cliff by waves wearing away at it

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27
Q

Attrition

A

A pieces of material knock each other they get smaller smoother and more rounded

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28
Q

Hydraulic action

A

Where waves crash into base of cliff forcing air into cracks. This exerts a pressure, cracks grow until rock detatches

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29
Q

Solution (erosion)

A

Soluble particles dissolved by acids in sea water

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30
Q

Lithology

A

The characteristics of the rock including the type, whether it’s permeable or impermeable, how porous it is

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31
Q

Isle of Purbeck, Jurassic coast

A

Resistant Portland limestone lies parallel to the coast

At points where this limestone is weaker erosion causes small coves eg Lulworth cove

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32
Q

Igneous rock erosion rate

A

Very slow
Interlocking crystals make rock strong and resistant
Few joints and therefore limited areas of weakness to exploit

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33
Q

Metamorphic rock erosion rate

A

slow
Crystallised sedimentary rock
Some folds and fractures to exploit

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34
Q

Sedimentary erosion rate

A

Moderate to fast
If cement between layers is weak then it will be weak
Younger rocks are weaker

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35
Q

Permeability (lithology)

A

The ability of water to pass through the rock.
Related to its previousness and porosity.

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36
Q

Pervious rocks

A

Eg limestone
Joints and bedding planes that water can flow through

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37
Q

How can groundwater flow weaken rocks

A

Flows through rocks layers removing binding cement

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38
Q

Carbonation

A

Acidic rainwater slowly dissolved the calcium carbonate in the limestone or chalk creating calcium bicarbonate which is taken away in solution

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39
Q

Hydrolysis

A

Water combines with minerals like granite and the chemical reaction creates salts and clay
Eg in Devon it has created Kaolin (porcelain china clay)

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40
Q

Freeze thaw

A

Water goes into cracks and freezes
This expands and breaks the rock

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41
Q

Horizontal bedding plane
1)Erosional processes
2)Main mass movement type

A

Undercutting by wave action can lead to development of wave cut notches and platforms

Main mass movement=rock fall

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42
Q

Sloping bedding plane (towards sea)
1)Weathering
2)Sub aerial processes

A

Large slabs of rock loosened by weathering slide off easily along bedding planes.

Sub aerial processes have a greater influence than marine processes leading to shelling cliffs

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43
Q

Sloping bedding plane (away from sea)

A

Rocks loosened by weathering and wave action are difficult to dislodge
Slope profile lowered by mass movement and weathering
Cliff face is rugged and uneven

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44
Q

Marram grass

A

Helps stabilise the unconsolidated sediment of the dunes and encourages other plants to grow there as well so helping plant succession

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45
Q

Ways vegetation helps stabilise unconsolidated sediment

A

1)roots of plants bind sediment particles together so harder to erode
2)When submerged plants provide protective layer sonnet exposed to moving water
3)Protect sediment from wind erosion by reducing wind speed due to friction

46
Q

What does geological structure of rock include

A

Strata
Bedding planes
Joints
Folds
Faults
Dip of the strata

47
Q

Joints

A

Vertical cracks

48
Q

Bedding planes

A

Horizontal cracks

49
Q

Dip of the strata

A

Angle at which rock strata lie

50
Q

Concordant

A

Bands of more resistant and less resistant rock parallel to coast

51
Q

Discordant

A

Bands of more resistant and less resistant rock perpendicular to coast

52
Q

Halophyte

A

Tolerate salt water around roots, tolerate being submerged in water or salt spray from the sea.

53
Q

Xerophyte

A

Tolerate very dry conditions, like on sand dunes where sandy soil has very little water due to drainage

54
Q

What factors affect size of wave

A

Fetch: stretch of ocean over which wind blows
Longer fetch -> larger wave

Wind speed

Duration of wind

55
Q

Rockfall

A

Occur when there is erosion at the base of cliffs creating overhang

Rock type must be resistant. As unconsolidated cliffs slump too quickly to allow overhangs to form.

Rock fragments fall due to gravity

56
Q

Slumping

A

Occurs in weak unconsolidated cliffs

These cliffs have little strength and are vulnerable to slip planes developing

Rainwater enters cliff increasing weight of soil and lubricating slip plane

Material slides along slip plane

57
Q

How are wave cut platforms formed

A

Horizontal bedding planes

Wave cut notch forms due to hydraulic action and abrasion

Notch increases in size

Wave cut platform forms when rockfall happens

58
Q

Longshore drift

A

Swash deposits material on the beach at 45 degrees

Backwash pulls material off beach at 90 degrees

This repeats moving sediment along the coastline

59
Q

How do spits form

A

-Sand or shingle beach ridge extending beyond a turn in the coastline
-Longshore drift current spreads out and loses energy leading to deposition
-Length of spit is determined by existence of secondary currents causing erosion
-Flow of river or wave action limits its length

60
Q

Detailed example of a spit

A

Spurn Head, Holderness coast
3.5 miles long
Grows 10cm a year

61
Q

Recurved spits

A

-A spit whose end is curved landward into a bay/inlet
-Seaward end curved landward into shallower water
-“Hook” may be made more pronounced by waves from a secondary direction to prevailing wind

62
Q

Example of a recurved spit

A

East Head West Wittering

63
Q

Tombolos

A

Sand/shingle bar that connects coastline to offshore island

64
Q

How are tombolos formed

A

-Spit/bar grows due to LSD joining island
-Formed due to wave refraction around island around island
-Area of calm water created
-Opposing Longshore currents may play a role

65
Q

Example of a tombolo

A

Chesil beach Dorset
-Swash aligned
-Faces SW

66
Q

How are beaches formed

A

Occur in littoral zone between low and high tide

Constructive waves with strong Swash and weak backwash allow a net increase of material

Longshore drift moves material along shoreline

67
Q

Barrier beaches

A

-Sand or shingle beach connects 2 areas of land with a shallow water lagoon behind
-Occurs when a spit grows so long that it extends across a bay closing it off

68
Q

Examples of barrier beaches

A

Many are found along Eastern Seaboard of the USA

Scapton, Devon

69
Q

Offshore bars

A

-Raised area of seabed that is found offshore
-Form adjacent to coastline
-Formed in areas with high levels of sediment and shallow water
-Form when sediment is transported on and off a beach

70
Q

Cuspate forelands

A

Roughly triangular shaped features extending out from shoreline

One hypothesis is due to growth of 2 spits from opposing longshore drift directions

71
Q

Yellow dunes

A

Mobile dunes
Marram grass/Lyme grass/Sandcouch

72
Q

Grey dunes

A

Less salt tolerant plants
Sea buckthorn, Dewberry
More organic matter and humus in soil

73
Q

Fixed grey dunes

A

hawthorn
Oaks
Maple
Ash
Climax species

74
Q

Dynamic equilibrium

A

The balance of all the factors affecting the coastal system. If there is a change to one factor the system will respond and there will be consequent changes

75
Q

Sources of Flamborough head sediment cell

A

-Deposition from river Humber
-Rockfall from cliffs
-Soft boulder clay
-Chalk from Flamborough head

76
Q

Transfers in Flamborough Head sediment cell

A

Longshore drift along Bridlington bay
-going southwards
-large waves from north east
-Increased erosion

77
Q

How is the Flamborough Head sediment cell being disrupted?

A

-Mappleton village intense erosion
-2m a year
-£2000000 spent on rock groynes and revetments
-Due to this there has been more erosion further south
-No beach to protect cliffs so sea reaches base of cliffs causing erosion

78
Q

Isostatic change

A

A LOCAL rise or fall in LAND level

79
Q

Eustatic change

A

Rise or fall in WATER LEVEL.
This is a GLOBAL change.

80
Q

Post glacial isostatic adjustment

A

Refers to uplift of land following removal of the weight of ice sheets

81
Q

How do sea levels change day to day?

A

-High/low tides alter local sea level every few hours
-Atmospheric air pressure influenced sea level (low pressure=slight rise)
-Winds can push water towards coast

82
Q

How much have sea levels risen by since last glacial period (ice age)

A

120m

83
Q

Eustatic fall in sea level

A

During glacial periods when ice sheets form on land in high latitudes, water evaporated from the sea is locked up on land as ice to sea levels fall.

84
Q

Isostatic fall

A

Weight of ice sheets causes earths coast to sag. When they melt the island surface slowly rebounds upward over 1000s of years. This lifts land out of sea

85
Q

Eustatic rise in sea level

A

At end of glacial period melting ice sheets return water to sea causing level to rise globally

86
Q

Isostatic rise

A

Lands can sink due to deposition of sediment (accretion)

87
Q

Raised beach + example

A

Old abrasion platform which has been lifted out of the sphere of wave activity

Developed when sea was at that level and then the sea level changed during the ice age

Fife Scotland

88
Q

Fossil cliff + example

A

Ayreshire Scotland 10m high

Land can be stressed downwards from post glacial adjustments, subsidence and accretion

89
Q

Rias + example

A

Drowned river valley

Caused by sea level rise flooding

Kingsbridge estuary Devon 500 to 1000m wide creeks

90
Q

Fjords + example

A

Deeper than adjacent sea
Submerged lip at seaward end
Post glacial isostatic adjustment slowly raises land out of sea

91
Q

Barrier islands + example

A

Offshore sediment bars.

Formed as lines of coastal sand dunes. Dunes are not eroded so become islands

Florida USA

92
Q

Dalmation coasts + example

A

Concordant coasts where sea has flooded landscape brewing long bays and parallel hilly islands

Croatia

93
Q

What effect does past and present tectonic activity have on sea level change?
Example

A

-Can lead to subsidence causing land to sink
-Oceanic plates sink

Turakirea head NZ shoreline has raised several metres by major earthquakes

94
Q

Eccentricity cycle

A

Earths orbit

95
Q

Obliquity cycle

A

Earths tilt

96
Q

Precession

A

A gradual change or wobble of earths axis

97
Q

Human reasons for spatial variations along the coast

A

-Coastal defences can cause starvation of sediment further south.
-Groynes interrupt longshore drift

Example: Hornsea

Hornsea groynes caused sediment starvation is mappleton so increased erosion

98
Q

Physical reasons for spatial variations along coast

Example

A

-Variations in cliff height
-Variations in rock resistance
-Mass movement susceptibility
-Debris from previous erosion

Example
Flamborough head shelters area south of it reducing impact of waves
Also has resistant chalk

99
Q

Ords

A

Deep hollows on the beach running parallel to the cliff at the base

100
Q

What influence do ords have

A

-Concentrate erosion in particular locations
-By allowing waves to directly attack the cliff with little energy dissipation

101
Q

Skipsea: Economic impacts of sea level rise

A

-10 caravan patches a year lost
-Property values declining
-No compensation for homeowners
-Loss of tourism revenue

102
Q

Social impacts of sea level rise in Skipsea

A

-Displacement of residents
-Stress over lost caravans/homes

103
Q

What’s needed for a storm surge to happen?

A

-Area of low pressure
-Strong winds around it
-High tides around the coast

104
Q

What physical factors make Bangladesh prone to flooding?

A

-Low lying. 0 to 3m above sea level
-Delta funnel shape
-Deforestation of coastal mangroves
-Floodplains of 3 major rivers incl Ganges

105
Q

Cyclone Sidr

A

-Heavy rain
-223 km/h winds
-$1.7 billion
-Contaminated drinking water
-Electricity and comms knocked out
-10000 deaths

106
Q

Economic costs of coastal recession

A

-Housing eg 24 homes at risk Skipsea
-Businesses
-Loss of tourism
-Infrastructure

107
Q

Social costs of coastal recession

A

-Impacts on health eg stress
-Relocation separates people
-Loss of livelihood
-Loss of amenity areas eg beaches

108
Q

What is ICZM

A

Integrated coastal zone management
Entire coastal zone is managed.
Ecosystems, resources, human activity
Recognises importance of zone to livelihoods
Involves all stakeholders

109
Q

Policy options of shoreline management plans

A

No active intervention
Managed realignment
Hold the line
Advance the line

110
Q

Example of a good ICZM

A

Blackwater Estuary Essex

Wildlife trust bought Abbots Hall Farm for market price
Paths and waterways for measure
5 breaches created in sea wall to form salt marshes

111
Q

Impacts of storm Xaver North Sea in England

A

100 000 homes lost power
Severe flooding Hull, Skegness, Whitby, Rhyl
2500 coastal homes flooded
-15 deaths

112
Q

Physical factors North Sea storm xaver

A

Sea gets shallower and narrower towards south
Increases height of storm surge

A level GEO (4 decks)

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