Coasts Flashcards

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1
Q

What is the littoral zone?

A

The boundary between the land and the sea

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2
Q

Why is the littoral zone dynamic?

A

Because the boundary moves depending on the tide, and sea level change

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3
Q

Define the back shore?

A

The area above the waves’ influence

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4
Q

Define the nearshore

A

The area where waves break

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5
Q

Define the offshore

A

The area out at sea beyond the waves’ influence

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6
Q

What short-term criteria classify coastlines?

A

River discharge, high/low tide, weather

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7
Q

What long-term criteria classify coastlines?

A

Geology, sea-level change, high/low energy, rate of erosion

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8
Q

What kind of landforms do high-energy coasts form?

A

Rocky landforms

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9
Q

Where do high-energy coasts occur?

A

Where there is a long fetch

Where erosion > deposition

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10
Q

What kind of rocks are resistant, and erode slower?

A

Igneous

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11
Q

What three factors erode the coast?

A

Sea, rain, wind

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12
Q

What are coastal plain landscapes formed from?

A

Weaker, younger, sedimentary rock

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13
Q

What feeds coastal plains?

A

Sediment from river discharge; ocean deposition

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14
Q

Describe concordant coasts

A

“Bands” of rock types parallel to the coast. This forms “smooth” coastlines or Dalmatian coasts

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15
Q

Describe discordant coasts

A

“Bands” of rock types perpendicular to the coast. Soft rock erodes quicker, forming headlands and bays

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16
Q

How do coves form?

A

A band of hard rock is eroded through, and the soft rock behind it starts to erode much quicker

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17
Q

How does a Dalmatian coast form?

A

Sea-level rise fills in the concordant valleys between ridges

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18
Q

Define strata

A

Layers of rock

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19
Q

Define bedding planes

A

Horizontal cracks/gaps, caused by time differences in when rocks formed

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20
Q

Define joints/fractures

A

Vertical cracks caused by movements in the earth

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21
Q

Define folds

A

Rocks buckle and crumple due to tectonic activity

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22
Q

Define faults

A

A rock fractures, then slips along the fault plane

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23
Q

Define dip

A

The angle of the strata

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24
Q

What is the order of coastal plant succession?

A

Embryo, fore-, yellow, grey, dune slack, woodland

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25
Q

What are colonising coastal plants called?

A

Pioneer species

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26
Q

How do pioneer species help plant succession?

A

They bind sand/soil, and add nutrients when they decay, allowing larger plants to grow

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27
Q

What kind of plants are found at yellow dunes?

A

Marram grass

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28
Q

What kind of plants are found at grey dunes?

A

Low shrubs

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29
Q

What kind of plants succeed pioneer species?

A

Invader species

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30
Q

What is the peak of a coastal ecosystem called?

A

Climatic climax community

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31
Q

What are the characteristics of a constructive wave?

A

Low waves, long wavelength
Strong swash, weak backwash
Beach gain
Wave energy absorbed by beach

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32
Q

What are the characteristics of a destructive wave?

A

High waves, short wavelength
Weak swash, strong backwash
Beach loss
Wave energy NOT absorbed; attacks the cliff face

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33
Q

Why does beach morphology change with wave type?

A

They are made of loose material; sand

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34
Q

When is sediment removed from beaches?

A

Winter

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35
Q

What are the characteristics of winter at a coast?

A

Storms and destructive waves

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36
Q

What wave type characterises summer at a coast?

A

Constructive waves

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37
Q

When is sediment returned to beaches?

A

Summer

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38
Q

Explain what season the beach profile is steepest

A

Summer, as sediment is deposited into a berm

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39
Q

Define abrasion

A

Sediment/rocks are thrown at the cliff base, eroding it

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40
Q

Define hydraulic action

A

Water trapped in cracks increases pressure, air expands when it subsides. This repeated process causes erosion

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41
Q

Define corrosion

A

Rock made of alkaline rock dissolves in slightly-acidic seawater

42
Q

Define attrition

A

Rock particles erode each-other in water

43
Q

What are the four types of erosion at coasts?

A

Abrasion, hydraulic action, corrosion, attirition

44
Q

What is the progression of erosional landforms at coasts?

A

Wave-cut notch → shoreline platform

Wave-cut notch → cave → arch → stack → stump

45
Q

How are joints and faults eroded?

A

Hydraulic action and abrasion

46
Q

How does longshore drift happen?

A

Waves act on the beach at angle, moving sediment in the direction of the prevailing wind

47
Q

How does a spit form?

A

Sand and shingle build up past a ‘bend’ in the coast

48
Q

How does a spit become recurved?

A

Wave refraction carries sediment around the bend

49
Q

How is a beach formed?

A

Waves swash and longshore drift

50
Q

How are offshore bars formed?

A

Backwashed sediment is deposited offshore

51
Q

What is a barrier beach?

A

A spit that connects two headlands

52
Q

How is a tombolo formed?

A

Waves travelling between two lands lose energy, depositing sediment that forms a joining beach

53
Q

How does a cuspate foreland form?

A

Longshore drift in different directions causes a triangle of deposition. Marshland may grow behind it

54
Q

How many sediment cells are in England and Wales?

A

11

55
Q

What is terminal groyne syndrome?

A

Groynes prevent longshore drift from bringing sediment further downdrift

56
Q

What are examples of soft engineering?

A

Beach nourishment, cliff regrading, dune stabilisation

57
Q

What are the subaerial processes?

A

Mass movement, weathering

58
Q

What are the mechanical weathering processes?

A

Freeze-thaw, salt crystallisation, wetting and drying

59
Q

Describe freeze-thaw weathering

A

Water in cracked rock freezes. It expands 10%.
The repeated action puts pressure on the rocks until the rock breaks.
The fragments accumulate at the base of the cliff as scree

60
Q

Describe salt crystallisation

A

Salt crystals deposited in cracks accumulate and apply pressure to the rock

61
Q

Describe wetting and drying

A

Clay-rich rocks expand when wet and contract when dry. This results in cracks for other weathering

62
Q

Describe chemical weathering

A

Rainwater + CO2 in atmosphere forms Carbonic acid.

This reacts with calcium carbonate in limestone to form calcium bicarbonate, which is soluble in water

63
Q

What is the ‘role’ of weathering?

A

To weaken cliffs, speeding up the rates of erosion.

64
Q

What is the rate of soil creep?

A

1cm / year

65
Q

Describe soil creep

A

The sum of many small, discrete movements of slope material caused by gravity

66
Q

Where are landslides most common?

A

On a weakened, saturated slope

67
Q

Describe slumping

A

Unconsolidated material slides down on itself at slip planes

68
Q

What is rockfall?

A

Loose rock falls down the cliff

69
Q

Where is the Dalmatian Coast?

A

Croatia

70
Q

Describe a horizontal cliff profile

A

Strata/bedding planes lay horizontal.

The causes a steep cliff

71
Q

Describe a seaward-dipping cliff profile

A

Strata/bedding planes point down towards the sea

Loose material can fall, making cliff unstable

72
Q

Describe a landward-dipping cliff profile

A

Strata/bedding planes point up towards the sky

Can be quite steep but stable

73
Q

What is the erosion rate of igneous rock?

A

0.1 cm / year

74
Q

What is the erosion rate of metamorphic rock?

A

0.3 cm / year

75
Q

What is the erosion rate of sedimentary rock?

A

0.5 - 10 cm / year

76
Q

Describe the structure of igneous rock

A

Few joints, less weaknesses

77
Q

Describe the structure of sedimentary rock

A

Many bedding planes and fractures

78
Q

What is eustatic sea level change?

A

The sea level changing

79
Q

What is isostatic sea level change?

A

The land level changing

80
Q

What might cause isostatic sea level change?

A

Glacial rebound

81
Q

Define glacial rebound

A

The rise of land masses that were depressed by the weight of glaciers

82
Q

What are the characteristics of an emergent coast?

A

Raised beaches, relic/fossil cliffs, fossil stump

83
Q

What is a fossil cliff?

A

A raised cliff that no longer touches the sea, exposing fossils

84
Q

What is a ria?

A

A submerged, unglaciated river valley filled with seawater

85
Q

What is a fjord?

A

A submerged, glaciated river valley filled with seawater

86
Q

What is a barrier island?

A

An island formed by submergent concordant coasts

e.g Dalmatian Coast

87
Q

What causes contemporary sea level change?

A

Global warming - melting polar ice cap

Thermal expansion - water takes up greater volume

88
Q

How much of contemporary sea level change is due to thermal expansion?

A

1.1 mm / year

89
Q

What proportion of contemporary sea level change is due to melting ice?

A

About two-thirds

90
Q

What is the rate of contemporary sea level change?

A

3.2 mm / year

91
Q

What is the name of holistic coastal management?

A

ICZM

Intercoastal Zone Management

92
Q

What is cliff regrading?

A

Reducing the angle of a cliff to increase stability

93
Q

When do rocky coasts form?

A

From resistant geology, in a high-energy environment

94
Q

When do coastal plains form?

A

Near low-relief areas, from the supply of sediment from terrestrial and offshore sources
In low-energy environments

95
Q

What landform does rotational slumping form?

A

Rotational scar

96
Q

What is scree?

A

Collection of rock fragments at the base of cliffs

97
Q

What landform does rockfall form?

A

Talus scree slopes

98
Q

What can cause terraced cliff profile?

A

Mass movement or isostatic sea level change

99
Q

What is a terraced cliff profile?

A

A cliff with a step-like shape

100
Q

What uncertainties are there about the increasing coastal flood risk?

A

Pace and magnitude of this change