coastal systems and landscapes Flashcards

1
Q

What percentage of the population live on coastal plains ?

A

50%

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2
Q

What are the inputs of a coastal system ?

A

Energy from waves,wind,tides and sea currents
Sediment
Geology of coastline
Sea level change

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3
Q

What are the components of a coastal system ?

A

Depositional and erosional Landforms and landscapes

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4
Q

What are outputs of a coastal system ?

A

Dissipation of wave energy
Accumulation of sediment above the tidal limit (eg. Sand dunes)
Sediment removed beyond local sediment cell

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5
Q

List 3 WAVE DOMINATED landforms.

A

Cliffs
Beaches
Spits

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6
Q

What is the coast?

A

The dynamic (changing) zone where the land meets the sea.

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7
Q

What are the sources of energy for waves?

A

Wind:
- spacial variations (strength and time that wind blows)
- fetch
- creation of waves
- direct wind erosion

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8
Q

What is the wave frequency?

A

The frequency is the number of wave crests passing a point each second.

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9
Q

Do constructive or destructive waves have a higher frequency?

A

Destructive

Constructive waves have a frequency of 6-8 a minute
Destructive waves have a frequency of 13-15 a minute

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10
Q

What are currents?

A

Currents are the permanent or seasonal movement of surface water in seas and oceans.

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11
Q

What are the types of currents?

A

Longshore currents

Rip currents

Upwelling

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12
Q

What are longshore currents?

A

When waves hit coastline at an angle, longshore currents generate a flow of water running parallel to the shoreline. This moves along the surf zone and transports sediment parallel to the shoreline.

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13
Q

What are rip currents?

A

Rip currents are strong currents moving away from the shoreline. They occur when seawater is piled up along the coastline.

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14
Q

What is upwelling?

A

Upwelling is when cold water moving upwards from deep in the ocean replaces the less dense surface water which creates nutrient rich cold ocean currents.

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15
Q

What are tides?

A

Tides are the periodic rise and fall in sea levels caused by gravitational pulling of the sun and the moon .

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16
Q

What is a neap tide? (Low)

A

Neap tides are when the sun and moon are perpendicular to each other causing the lowest monthly tidal range.
- usually occurs 2x a month

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17
Q

What is spring tide?

A

Spring tides are when the sun and moon are aligned in a straight line which produces the highest monthly tidal range.
- occurs 2x in a lunar month

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18
Q

What is tidal range?

A

Tidal range is the difference in the height of the sea water at high and low tide.

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19
Q

What are tidal surges (storm surges) ?

A

Occasions where meteorological conditions give rise to strong winds that produce much higher water levels than those at high tide. This is commonly affects …

  • the North Sea
  • east coast of Britain
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20
Q

What are sediment cells ?

A

Distinct areas of coastline which are separated from other areas by well-defined boundaries.
- erosion,transportation and deposition all occur within a sediment cell

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21
Q

What is an example of a low energy coastline ?

A

The Baltic Sea
Located in Northern Europe bordering Finland Estonia etc.

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22
Q

What is an example of a high energy coastline?

A

The south west of England such as Devon and Cornwall.

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23
Q

What are coastal sediment budgets?

A

The balance between sediment being added to and removed for the coastal system. This is calculated within each individual cell.

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24
Q

How many sediment cells surround England and Wales?

A

There are 11 main cells however these can be divided further into sub-cells.

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25
Q

What happens if the sediment budget is negative?

A

The shoreline retreats.

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26
Q

What happens if there is a positive sediment budget?

A

The shoreline builds towards the sea.

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27
Q

What processes are coastlines affected by?

A

Marine processes

Sub-aerial processes

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28
Q

What are the erosional processes?

A
  • hydraulic action
  • wave quarrying
    Air is forced into cracks which causes pressure and explosive effect upon retreat > weakens cliff
  • abrasion/corrasion
    Sediment hurled against rock face
  • attrition
  • solution/corrosion
    Calcium based rocks dissolve into sea water due to changes in ph where sea meets freshwater
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29
Q

What is lithology?

A

The characteristics of the rocks, especially permeability and resistance to erosion.

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30
Q

What is a concordant coastline?

A

A coastline where the layers of rock lie parallel to the coast.

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31
Q

What is a discordant coastline?

A

A coastline where the layers of rock lie at an angle to the coast (perpendicular).

32
Q

What is rock dip?

A

Rock dip is when the direction of the strata of the rocks effects the shape of landforms found on the coast.

33
Q

What are the types of marine transportation?

A

Traction
Saltation
Solution
Suspension

34
Q

What is longshore drift?

A

Longshore drift is the movement of sediment along the coastline due to the zig zag movement of waves carrying sediment up and down the beach.

35
Q

What are the reasons for marine deposition?

A

Waves slow down before breaking
Low energy waves
Abundant material
Sand and shingle accumulate faster than removed
Water percolates into beach as backwash moved down beach leaving sediment behind
Little energy in deeper water means sediment sinks to the bottom

36
Q

What is aeolian deposition ?

A

Aeolian deposition is where beach material is picked up by the wind and deposited in a different location.

37
Q

What are the types of aeolian deposition?

A

SURFACE CREEP - wind rolls or slides grains along the surface

SALTATION - wind is strong enough to temporarily lift the sand

38
Q

What causes aeolian deposition to be higher?

A

Wind coming from the sea during the day

Places with high tidal range have higher aeolian deposition due to the wide beach created during a low tide.

39
Q

What are the types of sub-aerial processes?

A

Landslides
Rockfalls
Mudflows
Rotational slip or slumping
Soil creep
Runoff

40
Q

What are the 3 types of weathering?

A

Mechanical weathering
Chemical weathering
Biological weathering

41
Q

How does rotational slip or slumping occur?

A

In areas where softer material overlies resistant materials, excessive lubrication from prolonged rainfall can cause the upper layer of the cliff to move down a concave slip plane in a rotational movement.

42
Q

List 3 examples of biological weathering.

A

Breakdown of rocks by action of vegetation or coastal organisms

Shellfish such as piddock drill into solid rock with their adapted shells

Animals can burrow,dig or nest on the cliff face causing it to weaken

43
Q

What are the types of chemical weathering ?

A

Decomposition
Solution
Oxidation
Hydration
Hydrolysis
Carbonation
Acid rain

44
Q

What are the types of mechanical weathering?

A

Freeze thaw - water enters cracks and expands as it freezes, making the crack larger. This process repeats until the rock eventually cracks, weakening the cliff face.

Salt crystallisation

Wetting and drying

45
Q

What is a mudflow?

A

Where heavy rainfall causes fine material to flow downhill.

46
Q

What are landslides?

A

Where cliffs made from softer rock or deposited material slip as a result of heavy rainfall.

47
Q

What is the difference between landforms and landscapes ?

A

Landscapes are the larger area e.g the entire sea coat and countryside, whilst landforms are the individual components that form these landscapes.

48
Q

What are cliffs? Give an example

A

Cliffs are walls of rock that often have vertical faces and retreat over time due to erosion and weathering eg. Purbeck coast in Dorset UK,

49
Q

How do wave-cut platforms form? include an example.

A

Wave-cut platforms are smooth platforms of rock which extend from the base of coastal cliffs. They form when the sea waves erode(primarily hydraulics action) at the cliff base causing a wave cut notch to form and the cliff to eventually become unstable and collapse due to gravity. This causes the cliff to retreat, leaving behind the wave cut platform at the low tide mark, e.g kimmeridge bay UK, where the rocks are easily broken along lamination plains.

50
Q

How do caves form?

A

Caves form when the cliff is undercut by abrasion and hydraulic action which causes an opening to be made which widened over time.

51
Q

How do geos form?

A

Geos are formed when a weakness in the cliff line cuts inland the crack, to for, a narrow steep sided inlet.

52
Q

How do blowholes form?

A

Blowholes form when a cave extends to the top of the cliff,by vertical erosion caused by marine processes. This causes hydraulic compression of sea water to be released at the opening which has a similar effect to the blowhole of a whale.

53
Q

How do arches form?

A

Arches form when a cave on one side of a headland extends horizontally and reaches the other side due to refraction around the headland and erosional processes such as abrasion and hydraulic action. This creates a hole in the headland as seen at Durdle door in the UK.

54
Q

How do stacks and stumps form?

A

Stacks are formed when an arch collapses due to sub-aerial weathering and marine processes weakening it. This leaves behind an isolated pole of rock known as a stack. The stack is then eroded further by the sea and it collapses, leaving behind a small portion of the rock known as a stump.

Both of these can be viewed at Old Harry’s rock in the UK and balls pyramid,Australia

55
Q

What are the two types of beach?

A

Drift aligned beaches and swash aligned beaches

56
Q

What are the characteristics of drift aligned beaches ?

A
  • longshore drift moves sediment
  • lots of sediment
  • where waves approach coast at an angle
    -can extend out where coast changes direction
57
Q

What are the characteristics of swash aligned beaches?

A

-waves break parallel to coast
-minimal longshore drift
-seen on irregular coastlines

58
Q

What are the features of a beach?

A
  • ridges and runnels
  • sand ripples
  • cusps
    -berm
    -storm beach
59
Q

What are ridges and runnels, how do they form?

A

These are a series of ridges running parallel to the coast near the low water mark.
Ridges are formed by deposition during backwash and runnels are formed when water runs back down the beach to the ocean.

60
Q

What are sand ripples, how do they form?

A

San ripples are small elongated ridges that form on the beach when waves and currents flow across loose sand which get dragged along the bottom and piled up.

61
Q

What are cusps, how do they form?

A

Cusps are semicircular depressions with coarser material around the edge and finer material in the middle.
They form when waves reach the same point and backwash scoures out the finer ,material in the centre.

62
Q

What are berms, how do they form?

A

Berms are a series of small ridges that form near the high water mark.
They form when sediment is deposited by the swash of constructive waves.

63
Q

What is a storm beach, how do they form?

A

A storm beach is a ridge found near the back of the beach composed of larger sediment.
They form when sediment is deposited by waves during a storm event, when water levels are above average.

64
Q

What is zonation?

A

The change in species over space

65
Q

What is succession?

A

The change in species in an ecosystem over time.

66
Q

What is a xerophyte?

A

A plant adapted to living in a very dry habitat like sand.

67
Q

How do sand dunes form?

A

1) sand accumulates against a feature and builds upper beach height
2) wind speed decreases behind the accumulation resulting in more deposition of sand
3) pioneer species colonise the embryo dunes which stabilises further dune migration
4) pioneer species leaves further reduce wind speed and capture more sediment while dying plants add humus to the soil
5) microclimate and soil conditions change as dunes develop allowing colonisation by additional non xerophyte species.

68
Q

What is plant succession ?

A

A directional change in the types of plant species that occupy a given area through time. This involves the processes of colonisation, establishment and extinction.

69
Q

What are climax vegetation?

A

The dominant mix of vegetation species that characterise an environment given time for colonisation to occur and reach stability.

70
Q

What is a psammosere?

A

An ecological succession that begins life on newly exposed coastal sand.
The most common example of this are sand dunes.

71
Q

What are sand dunes?

A

Small ridges or hills of sand found that the tip of a beach, above the maximum reach of waves.

72
Q

What is a tombolo?

A

A narrow piece of land,usually made from sand or gravel,that connects the mainland to an offshore island.

73
Q

What are simple and compound spits?

A

Spits are formed when sediment from longshore drift is deposited due to a change in the direction of the coastline, and they end where there is a river mouth present.
Simple spits are made of one narrow beach extending into the sea, whilst compound spits exhibit a spit with a number of recurved ends where extensions have been formed by further deposition.

74
Q

What is the proximal point on a spit?

A

The point where the spit is attached to the mainland.

75
Q

What is the distal point on a spit?

A

The furthest point from the mainland.

76
Q

What is a barrier island?

A

A barrier island is a long thin stretch of land lying parallel to the mainland coast that protects the land behind it from storms.
There is a calm lagoon or bay between the barrier island and the mainland and they are formed when low-lying spits are breached by the sea.

77
Q

What is a bar?

A

A bar is a spit that continues to join the mainland at either end, usually forming a bay behind it.