Geography - Physical > Coasts > Flashcards

Coasts Flashcards

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1
Q

What are sediment cells?

A

Coasts can be split into sections called sediment cells which are often bordered by prominent headlands

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2
Q

What is coastalisation?

A
  • the increasing concentration of human population within the coastal zone
  • many cities are located near the cost due to their old need to be near ports for growth
  • cities near coasts tend to have larger population densities (increases hazard risks like tsunamis)
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3
Q

How many sediment cells are in the UK?

A

11

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4
Q

What are the coastal inputs?

A

Marine:
- waves
- tides
Atmosphere:
- wind speed
- wind direction
Humans:
- pollution

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5
Q

What are the coastal outputs? (SORE)

A
  • sediment transfer
  • ocean currents
  • riptides
  • evaporation
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6
Q

What are the coastal transfers? (MWELT)

A
  • mass movement
  • weathering
  • erosion
  • longshore drift
  • transportation
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7
Q

What is hydraulic action?

A

Water crashing against the coastline causing material to be dislodged and carried away by the sea

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8
Q

What is corrosion?

A

A process of chemical erosion

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9
Q

What is attrition?

A

Rocks hitting against each other

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10
Q

What is abrasion?

A

Rocks carried by the sea are picked up by strong waves and thrown against the coastline

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11
Q

What is solution?

A

Weak acids dissolve alkaline rocks like chalk and limestone

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12
Q

What are the coastal stores?

A
  • beaches
  • dunes
  • spits
  • headlands and bays
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13
Q

What sediment source accounts for the majority of sediment?

A

Rivers

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14
Q

What are the sediment sources?

A
  • rivers
  • cliff erosion
  • wind
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15
Q

What is the sediment budget?

A

The balance of inputs and outputs in the coastal system

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16
Q

What is the littoral zone?

A

An area of land between the cliffs or dunes on the coast and the
sea

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17
Q

What are the short term factors impacting the littoral zone?

A
  • tides
  • storm surges
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18
Q

What are the long term factors impacting the littoral zone?

A
  • changes in sea level
  • human intervention
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19
Q

How are waves formed?

A
  • wind blows across the sea surface
  • energy from the wind is transferred to the water
  • the water moves in a circular motion
  • as the water gets more shallow waves grow in height
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20
Q

What are the factors effecting wave energy?

A
  • strength of wind
  • duration of wind
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21
Q

Constructive wave characteristics

A
  • long wavelength
  • 6-9 per minute
  • strong swash
  • weak backwash
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22
Q

Destructive wave characteristics

A
  • short wavelength
  • 25 per minute
  • weak swash
  • strong backwash
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23
Q

What is spring tide?

A
  • highest high tide and lowest low tide
  • occurs when the sun and the moon are in alignment, so their gravitational forces work with each other
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24
Q

What is neap tide?

A
  • lowest high tide and highest low tides
  • when the sun and the moon are
    perpendicular to each other, so their gravitational forces work against each other
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25
What are rip currents?
Powerful underwater currents occurring in areas close to the shoreline
26
What is wave refraction?
- the bending of waves as they approach an irregular coastline - causes energy to be concentrated on headlands and spread out in bays, leading to differential erosion
27
What is wave quarrying?
Breaking waves hit the cliff face directly pulling away rocks from a cliff face
28
What factors effect erosion?
- waves - beach size and presence - rock type
29
What is longshore drift?
- waves hit the beach at an angle determined by the direction of the prevailing wind - the waves push sediment up the beach in the swash - the wave then carries sediment back down the beach in the backwash - this moves sediment along the beach over time
30
What is mechanical weathering? (Describe freeze thaw and salt cyrstallisation)
Freeze thaw: - water enters cracks in rocks and then the water freezes and expands in volume causing cracks to develop - this can then cause rocks to break apart over time Salt crystallisation: - as seawater evaporates, salt is left behind - salt crystals will grow over time, forcing the cracks to widen
31
What is chemical weathering? (Describe carbonation and oxidation)
Carbonation: - carbon dioxide from the air mixes with rainwater to form weak carbonic acid - this acidic water dissolves carbonate rocks like limestone and chalk Oxidation: - when minerals become exposed to the air they become oxidised which increases volume causing the rock to crack
32
What is biological weathering? (Describe the effect of plant roots and birds)
Plant roots: - roots of plants growing into the cracks of rocks - exerts pressure which eventually splits the rocks Birds: - some birds such as Puffins dig burrows into cliffs weakening them
33
What is soil creep?
The movement of soil particles downhill
34
What is mass movement?
The movement of material down a slope under the influence of gravity
35
Mud slide
An increase in the water content of soil can reduce friction, leading to earth and mud to flow over underlying bedrock
36
Landslide
- large sections of cliff moving rapidly downhill along a straight slip plane under the influence of gravity - often triggered by factors like heavy rainfall, earthquakes or human activity - often occur on cliffs made of resistant rock, such as sandstone or limestone - also can occur when wave-cut notches lead to an unstable cliff which creates a landslide evetually leaving a wave cut platform
37
Slumping (Rotational slip)
- saturated material slides down a curved surface, often after heavy rain - the movement is rotational, causing the land to slip in a concave shape
38
Rock fall
- when fragments of rock break away from the cliff face and fall vertically down under gravity - most common on steep or vertical cliffs composed of rocks like limestone - weathering processes (usually freeze-thaw) widen joints and cracks in the rock weakening the rocks structure - the fallen material collects at the foot of the cliff to form a scree slope or debris pile
39
What is a wave-cut notch?
- erosion is concentrated around the high-tide line creating a wave-cut notch - as the notch becomes deeper the cliff face becomes unstable and collapses
40
Swash aligned beach
Waves break parallel to the coast
41
Drift aligned beach
Waves approach at an angle, so sediment travels along the beach, which may form a spit
42
What is a spit?
- longshore drift deposits sediment at a bend in the coastline - sediment builds out into the sea, forming a spit - end curves with wind/wave changes - sheltered area forms a salt marsh
43
What is a barrier beach/bar?
- occurs when a beach or spit extends across a bay to join two headlands - traps water forming a lagoon which is separated from the sea
44
What is a tombolo?
A bar that connects the mainland to an offshore island
45
What is an offshore bar?
An offshore region where sand is deposited, as the waves don’t have enough energy to carry the sediment to the shore, they absorb wave energy
46
What are sand dunes?
- sand is transported inland by wind - obstacles cause sand to accumulate - as sand builds up, it forms embryo dunes - plants colonise and stabilise the sand - over time, dunes become fixed
47
Isostatic sea level change
- when the land rises or falls relative to the sea - localised change - for example tectonic activity
48
Eustatic sea level change
- affects the sea level across the whole planet - may be due to thermal expansion/contraction
49
Contemporary sea level change
Since 1880 sea levels have increased by around 23cm
50
Hard engineering examples
- groynes - sea wall - rock armour - revetments
51
Groynes
Timber protrusions that trap sediment from LSD
52
Groynes pros and cons
- build up the beach - cost effective - visually unappealing - increases erosion down shore
53
Sea wall pros and cons
- highly effective - tourism benefits - expensive to construct and maintain - visually unappealing
54
Rock armour
Large rocks that reduce wave energy
55
Rock armour pros and cons
- cheap - can be used as extra defence for sea walls to increase life span - looks unattractive (probably woulnd't be effective at a touristic place) - access to beach is limited
56
Revetments
Wooden or concrete ramps that help absorb wave energy
57
Revetments pros and cons
- cheap - less beach material is eroded compared to a sea wall - are not suitable for high energy coasts and need constant maintenance due to short life span - they affect the coastal system and reduce the input of sediment
58
Soft engineering examples
- beach nourishment - dune stabilisation - managed retreat
59
Beach nourishment
Sediment is taken from offshore sources to build up the existing beach
60
Beach nourishment pros and cons
- cost effective - looks natural - needs constant maintenance - offshore dredging may have consequences on habitats
61
Dune stabilisation
Marram grass can be planted, the roots help bind the dunes, protecting the land behind
62
Dune stabilisation pros and cons
- cost effective - creates a habitat - vegetation must be carefully managed to avoid trampling by humans which reduces access to beaches - time consuming protecting vegetation
63
Managed retreat
Allowing low-lying areas to flood and be eroded (usually where the land is of low value)
64
Managed retreat pros and cons
- creates a new habitat - eroded material can encourages the development of beaches and salt marshes - farmers have to be given compensation
65
Shoreline Management Plans (SMPs)
- there is an SMP for each UK sediment cell - different factors are considered when choosing a management options: the economic value of assets that could be protected and the ecological value of land
66
What are emergent coastal landforms and how do they form?
- emergent landforms are features exposed by a relative fall in sea level, usually due to isostatic rebound - common after glaciation when land rises as ice melts
67
Name and describe two emergent coastal landforms
Raised beaches - former wave-cut platforms now above sea level Relict cliffs - cliffs inland from the current coastline, often with notches and caves
68
What are submergent coastal landforms and how do they form?
- submergent landforms are created by a rise in sea level (eustatic change) - often due to melting ice caps or thermal expansion of oceans
69
Name three submergent coastal landforms
- Rias - Fjords - Dalmation coasts
70
Describe rias and give an example
- rising sea levels flood narrow winding inlets and river valleys - they are deeper at the mouth of the inlet, with the water depth decreasing further inland - e.g. Kingsbridge Estuary in Devon
71
Describe fjords and give an example
- rising sea levels flood deep glacial valleys to create natural inlets and harbours - they are deeper in the middle than they are at the mouth, with the shallower section showing where the glacier left the valley - e.g. Sognefjord in western Norway
72
Describe dalmation coasts and give an example
- submerged parallel valleys creating long, narrow offshore islands - e.g. Dalmation region in Croatia
73
How might climate change affect submergent and emergent features?
- climate change can increase submergence through sea-level rise, submerging low-lying coasts and altering rias and fjords - it may overwhelm some emergent features
74
What is glacial subsidence and how does it relate to coastal landforms?
- land sinks because of the weight of a glacier sitting on it - when the ice melts, that weight is removed - the land doesn’t bounce back quickly, it slowly rises again over thousands of years - this slow rising is called isostatic rebound
75
Example of tectonic activity causing subsidence
2004 Indian ocean earthquake, caused a city to sink by 0.5 meters
76
Thermal expansion
- water gets warmer - heat expands - higher volume of water
77
Positive feedback example
- coastal erosion removes beach material - less protection for cliffs - increased wave energy reaches cliffs - more erosion
78
Negative feedback example
- a section of a cliff is eroded by marine processes - the cliff becomes unstable and collapses - the collapsed material gathers at the base of the cliff, forming a temporary protective layer - this protects the cliff from further erosion by absorbing wave energy
79
What is the difference between low energy and high energy coasts?
Low energy coasts have limited wave action and deposition dominates; high energy coasts face powerful waves and strong erosion
80
What are currents and tides, and why are they important?
Currents are flows of water caused by wind or salinity; tides are the daily rise and fall of sea levels caused by the moon's gravity - both influence coastal erosion and deposition
81
What is traction in coastal processes?
Large sediment (like boulders and pebbles) are rolled along the seabed by the force of water
82
What is coastal runoff?
- the flow of water from land to the sea, carrying sediments and pollutants - can affect coastal erosion and water quality
83
How are beaches developed?
- formed by the accumulation of sediment deposited by waves, tides and currents - constructive waves build up beaches - destructive waves may erode them
84
How are offshore bars formed?
- sediment is deposited by longshore drift in shallow water - waves and currents move sediment along the coast and when wave energy decreases offshore, sediment accumulates to form these bars
85
How are barrier beaches (bar) formed?
- sand is deposited by longshore drift, creating a narrow sandbank parallel to the coastline - typically form in sheltered areas where wave energy is low
86
What major change in sea level occurred during the last 10,000 years?
Sea levels rose significantly after the last Ice Age, as global temperatures increased, causing glaciers to melt and contributing to the rise in sea level by about 120 meters
87
How will recent and predicted climatic change impact coasts?
Sea level rise leads to increased coastal erosion, flooding and storm surges, threatening coastal habitats and communities
88
Integrated Coastal Zone Management (ICZMs)
- environmental protection is prioritised over economic development - must involve all stakeholders - in 2013 the EU adopted a new initiative which promotes the use of ICZMs
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