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Geography- Coasts > Systems and Processes > Flashcards

Systems and Processes Flashcards

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1
Q

What are the 4 sources of energy in the coastal system?

A

Wind
Waves
Currents
Tides

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2
Q

Wind: When is wave energy likely to be higher?

A

When wind speeds are greater

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3
Q

Wind: How are waves created?

A

Wind transfers energy when it blows over the sea surface due to friction

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4
Q

Fetch

A

Distance of open water over which wind blows uninterrupted by major obstacles
Determines the magnitude and energy of waves

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5
Q

Waves: What happens as they reach the coast?

A

Approach shallower water
Sea bed friction increases so base of the wave slows down
Increases wave height and steepness
Until upper part of the wave plunges forward

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6
Q

Waves: Constructive wave characteristics

A 
Low frequency (6-8 a min)
Low wave height and long length (up to 100m)
Swash > backwash, as there's insufficient energy to pull sediment off the beach
Material slowly but constantly moved up the beach (ridges)
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7
Q

Waves: Destructive wave characteristics

A

High frequency (10-14 a min)
High wave height and short length
Backwash > swash, material pulled down beach, wave’s force can project shingle to back of beach (storm beach)
Little material moved up the beach
Strong backwash inhibits swash of next wave

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8
Q

Waves: Link between constructive and destructive waves

A 
Constructive waves build up beaches
Steeper profiles
Encourages destructive waves to erode
Shallower profiles
Encourages constructive waves etc
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9
Q

Waves: Wave Refraction

A

Occurs when waves approach an irregularly shaped coastline
Near shore, slow down due to friction
Parts of the wave that haven’t reached shore bend- travel faster
Energy focused on headland- increasing erosion
Waves reaching the bay have less energy, so deposit material

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10
Q

Currents: Current

A

The permanent or seasonal movement of surface water in the seas and oceans

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11
Q

Currents: 3 types of current

A

Longshore Current
Rip Currents
Upwelling

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12
Q

Currents: Longshore Current

A

Occurs when waves have an angled approach to the coastline

Transports sediment

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13
Q

Currents: Rip Currents

A

Strong currents moving away from the shoreline

Develop when sea water is piled up along the coastline by incoming waves

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14
Q

Currents: Upwelling

A

Movement of cold water from deep in oceans to the surface

More dense, cooler water replaces warmer surface water, creating nutrient rich cold ocean currents

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15
Q

Tides: Tides

A

The periodic rise and fall in the level of the sea, caused by the pull of the sun and moon

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16
Q

Tides: Why does the moon have a greater influence on tides than the sun?

A

Because it’s closer to the Earth

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17
Q

Tides: Spring Tide

A

Highest monthly tidal range, as sun and moon are aligned so greater force

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18
Q

Tides: Neap Tide

A

Lowest monthly tidal range where sun is perpendicular to moon, with tides between 10-30% lower than average

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19
Q

Tides: What 2 factors do they determine?

A

Upper and lower limits of erosion and deposition

Amount of time each day the shoreline is exposed to sub aerial weathering

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20
Q

Tides: What causes tidal (storm) surges? What makes them worse?

A

They occur when meteorological conditions give rise to strong winds, producing much higher water levels than high tide, increasing erosion in the short term
They are worsened by spring tides

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21
Q

Low Energy Coast

A

A coastline where wave energy is low and the rate of deposition exceeds the rate of erosion
Contains depositional features
i.e. Baltic Sea

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22
Q

High Energy Coast

A

A coastline where strong, steady prevailing winds create high energy waves, so the rate of erosion exceeds the rate of deposition
Contains erosional features
i.e. North Cornish Coast

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23
Q

Sources of sediment

A

Offshore sand banks
Cliff erosion
Shells and coral fragments
Fluvial sources

24
Q

Sediment Cell

A

A distinct area of coastline separated from another by a well-defined boundary like a headland or stretch of deep water

25
Q

Coastal Sediment Budget

A

Balance between sediment being added and removed from the system

26
Q

Sediment Surplus

A

A positive budget where more material is added than removed

Shoreline extends seaward

27
Q

Sediment Deficit

A

A negative budget where more material is removed than added

Shoreline retreats landward

28
Q

Marine Process

A

Operates upon the coastline and is connected with the sea

Waves, tides, LSD

29
Q

Aeolian Process

A

Transport or deposition of sediment by wind

30
Q

Sub-Aerial Process

A

Operates on land and affects the shape of the coastline

31
Q

Abrasion

A

Sand, shingle in water grinding down the cliff face

32
Q

Wave Quarrying

A

Air forced into cracks under high pressure when a wave impacts a cliff face
Widens them
Cracks grow over time, destabilising the cliff

33
Q

Cavitation

A

Compression of air causes sea water to be compressed in crack
Air fizzes out of water due to reduced pressure when the wave recedes
Enlarges fissures with in the joints

34
Q

Hydraulic Action

A

Impact of the waters’ sheer force on the rocks

Puts pressure on them so they weaken

35
Q

Attrition

A

Rocks carrying out abrasion are warn down

Become smaller and rounder

36
Q

Solution

A

Dissolving of calcium based rocks in acidic water

Acidity caused by dissolved CO2

37
Q

Marine Processes of Erosion

A 
Abrasion
Wave quarrying
Cavitation 
Hydraulic action
Attrition 
Solution
38
Q

Marine Processes of Transportation

A

Traction
Saltation
Suspension
Solution

39
Q

Why does Marine Deposition occur?

A

Abundant supply of material

Waves lose energy -decreased velocity -decreased volume of water

40
Q

Aeolian Processes of Transportation

A

Surface Creep

Saltation

41
Q

Surface Creep

A

Wind rolls grains along the surface

42
Q

Saltation

A

Fine particles lifted into the air and drift horizontally

43
Q

Sub Aerial Processes of Erosion

A

Mechanical weathering
Biological weathering
Chemical weathering

44
Q

Example of Mechanical Weathering

A

Frost shattering

45
Q

Example of Biological Weathering

A

Seaweed- roots bury into rocks, exploit cracks

Rabbits burrow- exploit cracks

46
Q

Examples of Chemical Weathering

A

Oxidation (dissolved O2 reacts with minerals)
Carbonation (acid rain dissolving minerals)
Hydration

47
Q

Discordant Coastline

A

Perpendicular to bands of rock

48
Q

Concordant Coastline

A

Parallel to bands of rock

49
Q

Examples of resistant rock

A

Granite

Chalk

50
Q

Examples of less resistant rock

A

Limestone

51
Q

Landslide key points

A

Cliffs (steep) made of softer rock
Failure lubricated- often after heavy rainfall
Mass moves downslope in straight line, fractures into smaller pieces at the foot

52
Q

Rockfall key points

A

Near vertical slope
Caused by freeze thaw weathering or undercutting in the intertidal zone
Resistant rock breaks up and falls in small chunks

53
Q

Mudflow key points

A

Soil saturated
Excess water can’t percolate deeper, layers become fluid and flow downhill
Caused by prolonged heavy rainfall
Soft rock i.e. boulder clay

54
Q

Rotational Slump key points

A

Softer material overlies harder material
Marine processes erode and undermine base
Saturated clay slips along plane
Moves with rotation

55
Q

Soil Creep key points

A

Continuous movement of individual soil particles downslope
1 cm a year, slope bigger than 5 degrees
Caused by: freeze thaw -repeated expansion and contraction

56
Q

Runoff key points

A

Moves fine material downslope

Overland flow causes thin, continuous layer of water- washes silt and clay sized particles downslope

Geography- Coasts (7 decks)

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