Coastal Systems And Landscapes Flashcards Preview

A Level Physical Geography > Coastal Systems And Landscapes > Flashcards

Flashcards in Coastal Systems And Landscapes Deck (122)
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1
Q

Define system

A

A set of interrelated components working together towards some kind of process

2
Q

Define closed system and give an example

A

Closed systems have transfers of energy both into and beyond the system boundary, but no transfer of matter
Eg carbon cycle

3
Q

Define open system and give an example

A

Where matter and energy can be transferred from the system, across the boundary and into the surrounding environment
Eg hydrological cycle

4
Q

Define isolated system

A

Isolated systems have no interaction with anything outside the system boundary.
No input / output of matter of energy

5
Q

Define dynamic equilibrium

A

Where there is a balance between inputs and outputs of a system

6
Q

Define positive feedback

A

Where the effects of an action are multiplied by the following knock on effects

7
Q

Define negative feedback

A

Where the effects of an action are cancelled out by its following knock on effects

8
Q

Define subsystems

A

The earth is divided into 5 subsections / spheres

9
Q

Name the earths 5 subsystems

A
Atmosphere
Lithosphere
Biosphere
Hydrosphere
Cryosphere
10
Q

Define cascading system

A

The earths subsystems interlink to form a cascading system

11
Q

Define fetch

A

Distance travelled by waves

12
Q

Define prevailing wind

A

Most frequent wind direction

13
Q

Define wavelength

A

Distance from one wave crest to the next

14
Q

Define wave height

A

Distance from wave crest to trough

15
Q

Define swash

A

Wave travelling up the beach

16
Q

Define backwash

A

Wave travelling from the beach back into the sea

17
Q

Define constructive wave

A

Characteristics mean more sediment is brought onto the beach in the swash than is removed by the backwash

18
Q

Define destructive wave

A

Characteristics mean more sediment is removed from the beach by backwash than is brought onto it

19
Q

Give an example of positive feedback in a system

A

Global temp rises -> oceans warm up -> warm water unable to dissolve gas -> more CO2 released -> more CO2 in atmosphere -> greenhouse effect -> global temp rise

20
Q

Give an example of negative feedback in a system

A

Increase use of fossil fuels -> more CO2 in atmosphere -> global temp increase -> more plants grow -> absorb CO2 -> reduce in CO2 in atmosphere -> less global warming

21
Q

Facts about the atmosphere

A

• nitrogen (78%), oxygen (21%), other gases (1%)
• atmosphere becomes thinner the higher up it is until it reaches space
• divided into 5 layers:
- troposphere
- stratosphere
- mesosphere
- thermosphere
- exosphere
• purpose to filter and stop UV radiation entering the earth

22
Q

Facts about the biosphere

A

• area on or near the earths surface where life is found
• subdivided into 3 sections:
- lithosphere (rocks)
- atmosphere (air)
- hydrosphere (water)
• stretches 10km above sea level and 8km deep

23
Q

Facts about the lithosphere

A
  • includes the upper mantle and crust
  • ‘lithos’ is Greek for rock
  • average 75km thick
  • sits on top of asthenosphere
24
Q

Facts about the hydrosphere

A
• includes all water on, above and below earth
- lakes
- sea
- rivers
- ice
- clouds
• water can be liquid, vapour or ice
25
Q

Facts about the Cryosphere

A

• the frozen water part of the earths system

  • snow
  • freshwater ice
  • sea ice
  • glaciers
  • permafrost
26
Q

How might the Cryosphere interact with the lithosphere?

A

Permafrost
Freeze thaw
Glacial erosion

27
Q

How can you link the hydrosphere to the lithosphere?

A

Coastal / river erosion -> sediment ->. Deposition

28
Q

How can you link the lithosphere to the biosphere?

A

Rocks in the lithosphere break down to form soil

Volcanoes - lahar mud flows

29
Q

Is the coast a closed or open system?

A

Open

30
Q

How can the dynamic equilibrium of the coastal system be upset?

A

Eg increased deposition of sediment on the beach but no corresponding change in sediment being removed

31
Q

Inputs of the coastal system

A
• energy from
- waves
- wind
- tides
- sea currents
• sediment
• geology of coastline
• sea level change
32
Q

Components in the coastal system…

A
  • erosional landforms and landscapes (caused by erosional processes)
  • depositional landforms and landscapes (caused by wind and water transport)
33
Q

Outputs in the coastal system…

A
  • dissipation of wave energy
  • accumulation of sediment above the tidal limit
  • sediment removed beyond local sediment cells
34
Q

How might the lithosphere interact with the atmosphere?

A

Weathering of rocks (rain wind etc)

Volcano -> ash cloud

35
Q

What are the ‘shore’ areas in a coastal transect?

A

Backshore
Foreshore.
Inshore
Offshore

36
Q

Where is the backshore area found and when do things occur here?

A

Area between HWM and landward limit of marine activity

Changes normally occur here only during storm activity

37
Q

Where is the foreshore area found and what occurs here?

A

Area between HWM and LWM

Most important zone for marine processes in times not effected by storm activity

38
Q

Where is the inshore area found?

A

Area between LWM and point where waves have no influence on land beneath them

39
Q

Where is the offshore mark found and what activity takes place here?

A

Area beyond the point where waves cease to impact upon seabed
Activity limited to deposition of sediment

40
Q

Give an example of negative feedback at the coast

A

Beach in dynamic equilibrium -> sediment eroded from beach during a storm -> sediment deposited forming offshore bar -> waves now forced to break before reaching the beach, dissipating their energy + reducing erosion at beach -> when storm calms, normal wave conditions erode offshore bar -> beach in dynamic equilibrium

41
Q

What are waves formed by?

A

Winds on the surface of the sea - can be both local and distant winds

42
Q

What are the factors that affect the strength of waves?

A

Wind velocity
Wind duration
Fetch

43
Q

Which winds that hit the UK are most prevailing?

A

Come from South West, Atlantic Ocean

44
Q

Describe how waves are formed

A

Wind causes friction at surface of sea
Friction causes a swell (wave)
Energy from wind causes water to move forward in an elliptical motion (circular)

45
Q

Give the wave energy equation

A

Energy =(prop) wavelength x wave height^2

46
Q

Give the characteristics of a constructive wave

A
Sloping wave front
Wide wavelength
Strong swash
Weak backwash
Low frequency (6-8/min)
47
Q

Give the beach characteristics created by constructive waves

A

Wide, gently sloping beach

Berms (ridges)

48
Q

Give the characteristics of destructive waves

A
Steep wave front
Short wavelength
Weak swash
Strong backwash
High frequency (10-14/min)
49
Q

Give the beach characteristics created by destructive waves

A

Narrow steep beach profile

Trough

50
Q

When does wave refraction occur?

A

When waves are not a regular shape when they reach the shore

51
Q

What changes in the waves as they reach the shore during refaction?

A

Wave depth increases
Wave velocity decreases
Waves are bent towards the shoreline that is slowest
Waves crash to mirror the seabed contour

52
Q

Which type of waves converge during wave refraction and where do they converge to?

A

Destructive waves converge towards headlands, eroding it

53
Q

Which type of wave diverge during wave refraction and where do they diverge to?

A

Constructive waves diverge towards bays, depositing sediment there

54
Q

Define global ocean conveyorbelt

A

Constant moving system of deep ocean circulation driven by temperature and salinity

55
Q

What is the global ocean conveyorbelt driven by?

A

Combination of thermohaline currents in the deep ocean and wind driven currents on the surface

56
Q

How does the global ocean conveyorbelt link to the coast?

A

The temperature of the water changes when it enters areas closer to coastlines

57
Q

Define upwelling

A

A process in which deep, cold water rises towards the surface

58
Q

Describe how upwelling takes place

A

Winds blowing across the ocean surface push water away.

Water then rises up from beneath surface to replace the water.

59
Q

Why do areas of upwelling often have high biological activity?

A

The water that rises to the surface is typically colder and is rich in nutrients, which fertilise the surface waters

60
Q

What are ocean currents driven by?

A

Wind
Water density differences
Tides

61
Q

Define ocean currents

A

The movement of a body of water from one location to another

Generally measured in m/s or in knots

62
Q

What are currents driven by?

A

The rise and fall of tides
Wind
Thermohaline currents

63
Q

How does the rise and fall of tides impact on currents?

A

Tides create a current in oceans which are strongest near the shore and in bays and estuaries along the coast = tidal currents.

64
Q

Give some information about tidal currents

A

Change in a very regular pattern and can be predicted for future dates
Strong tidal currents may travel at speeds of 8 knots or more

65
Q

How do winds impact on currents?

A

Winds drive currents that are on / near the ocean surface
In coastal areas they drive currents on a local scale -> upwelling
Global scale = winds drive currents that circulate ware for thousands of miles throughout ocean basins

66
Q

How does thermohaline circulation impacts on currents?

A

Currents occur at both deep and shallow ocean levels and move much slower than tidal / surface currents

67
Q

How do currents affect the earth’s climate?

A

By driving warm water from the equator and cold water from the poles around the earth

68
Q

Define rip current

A

Powerful, narrow channels of fast moving water
Move at speeds of up to 8 feet/second
They flow away from the shoreline towards the sea

69
Q

What is a longshore current?

A

When a wave reaches the coastline, it releases a short burst of energy that generates a current which runs parallel to the shoreline = longshore current

70
Q

What are longshore currents affected by?

A

Velocity of the wave
Angle of the wave / beach

E.g. Longshore currents increase velocity when…. wave breaks at steeper angle / steeper beach slope / high wave

71
Q

Define flood current

A

An incoming tidal flow

72
Q

Define ebb current

A

An outgoing tidal flow

73
Q

Define slack water / slack tide

A

The period between flood and ebb tides when there is little / no current

74
Q

What are tides caused by?

A

The gravitational pull of the moon and the sun

75
Q

What are tides?

A

Very long period waves that move through the oceans in response to the forces from the moon and sun.
Tides start off in the oceans and move toward the coastlines where they appear as the regular rise and fall of the sea surface

76
Q

Define high tide and low tide

A

High tide - when the crest of the wave reaches the shore

Low tide - when the trough of the wave reaches the shore

77
Q

Define tidal range

A

The difference between high and low tide

78
Q

When do spring tides occur? Why?

A

During full moons / new moons
When the earth, sun and moon are in alignment
The gravitational pull of the sun is added to that of the moon, causing the oceans to bulge a bit more than usual

79
Q

How do spring tides affect tides and how often do they occur?

A

Average tidal ranges are slightly larger

Happen twice each lunar month

80
Q

When do neap tides occur? Why?

A

When the sun and moon are at right angles to each other

The solar tide partially cancels out the lunar tide and produces moderate tides

81
Q

How do neap tides affect tides and how often do they occur?

A

Tidal range is smaller

Happens twice each lunar month

82
Q

What is the difference between currents and tides?

A

Currents move left and right, tides move up and down
Currents occur due to tides, winds and thermohaline circulation, tides occur due to gravitational forces from the moon and sun

83
Q

What are the characteristics of a low energy coast?

A

Low wave energy
Low rate of erosion (sometimes higher rate of deposition)
Landforms include beaches and spits

84
Q

What are the characteristics of a high energy coast?

A

High wave energy
Fast rate of erosion
Landforms include headlands, cliffs, WCP

85
Q

What factors influence the regular pattern of the tide?

A

Morphology of the seabed
Proximity to landmass
Coriolis force

86
Q

What is tidal range significant for?

A

Shipping routes
Coastal erosion
Leisure reasons

87
Q

When do tidal surges occur and what is their effect?

A

Occur at times of intense low pressure (a depression)

Produce very high sea levels and violent storms

88
Q

Name the two types of geomorphological processes

A

Marine processes

Sub aerial processes

89
Q

Define marine process

A

Coastal processes that link with the sea e.g. Waves, tides, LSD

90
Q

Define subaerial process

A

Take place on land but determine the shape of the coastline e.g. Weathering, mass movement, run off

91
Q

Name the types of marine processes

A
Hydraulic action
Wave quarrying
Abrasion
Attrition
Solution
92
Q

Define hydraulic action

A

The weakening of rocks by the force and pressure caused by the water hitting them

93
Q

Define wave quarrying

A

Waves compress air into fissures / joints in the cliff face
As the wave withdraws the air is quickly released like an explosion
This weakens / breaks off the rock

94
Q

Define abrasion

A

The weakening of rocks by sediment in the sea being thrown against the cliffs / WCP

95
Q

Define attrition

A

Material in the sea wear down each other as they collide in the water

96
Q

Define solution

A

When acidic water dissolves calcium based rocks e.g. Limestone
Carbon based rocks at the coast can be eroded by rainwater flow from the land as the pH of this is slightly acidic
Salt from the sea water residue in the rocks evaporates, forming salt crystals which as it expands, weakens the rock

97
Q

Name the factors that affect the rate of marine erosion

A
Wave steepness
Breaking point
Fetch
Sea depth
Coastal configuration
Beach presence
Human activity
98
Q

How does wave steepness affect the rate of coastal erosion?

A

Steeper waves carry more energy -> more erosive

99
Q

How does breaking point of waves affect the rate of coastal erosion?

A

Closer the waves break to the shore, The more they erode rocks

100
Q

How does fetch affect the rate of coastal erosion?

A

Waves have more energy if they have travelled a longer distance before reaching the shore -> more erosive

101
Q

How does sea depth affect the rate of coastal erosion?

A

A steeper-shelving sea bed by the shore -> higher and steeper waves

102
Q

How does coastal configuration affect the rate of coastal erosion?

A

Headlands attract high energy, destructive waves through wave refraction
Concordant / discordant -> more / less resistant rocks exposed

103
Q

How does beach presence affect the rate of coastal erosion?

A

Beaches dissipate wave energy -> lower rate of erosion
Steep narrow beaches -> dissipate flatter waves
Flat, wide beaches -> dissipate high/rapid energy outputs (spread over a large area)
Shingle beaches -> dissipate steep waves by friction/percolation

104
Q

How does human activity affect the rate of coastal erosion?

A

Higher rate of erosion -> removing beach material

Lower rate of erosion -> sea defences (may increase erosion elsewhere)

105
Q

Define lithology

A

Refers to the characteristics of the rock

Esp resistance to erosion and permeability

106
Q

Define differential erosion

A

The variation in rates that different rock types erode

107
Q

Define concordant coastline

A

Where rock types run parallel to the coastline

E.g. Lulworth Cove

108
Q

Define discordant coastline

A

Where rock types run perpendicular to the shoreline

Et Swanage bay

109
Q

Define the ‘dip’ of the rocks

A

The angle at which rock layers are aligned within the rock

110
Q

What does the dip of the rock affect?

A

Affects the steepness of cliff
Steepest cliffs - where rock strata is horizontal / dipping inland
Sloping cliffs - where rock strata dips towards the sea

111
Q

Name the types of marine transportation

A

Traction
Saltation
Suspension
Solution

112
Q

Define traction

A

Large rocks / boulders slide along the seabed in high energy locations due to the movement of the water

113
Q

Define saltation

A

Small stones bounce along the seabed / beach in high energy locations , dislodging other stones

114
Q

Define suspension

A

Very small particles of sand and silt that are carried in/ picked up by the water, giving it a murky appearance

115
Q

Define solution

A

Dissolved materials are transported within the mass of moving water

116
Q

What is the official name for sand dunes?

A

Psammosere

117
Q

What are sand dunes created by?

A

Aeolian transportation

Aeolian deposition

118
Q

Name the types of aeolian transportation that causes sand dunes to form?

A

Surface creep

Saltation

119
Q

Define fluid threshold velocity

A

Wind speed needed to entrain sand particles

So that sand dunes form

120
Q

What are the conditions needed for sand dunes to form?

A

Lots of fine sediment - from rivers/seas
High wind energy - big fetch
Large tidal range
Large backshore area

121
Q

Name the types of sand dunes

A
Embryo dune
Fore dune
Yellow dune
Grey dune
Dune slack
Mature dune
122
Q

How do sand dunes form?

A

Sand is deposited when an obstacle traps it e.g. Driftwood, a rock, a bush
As sediment accumulates the mound of sand becomes larger -> dune
Plant e.g. Marram grass, sea couch
The roots interlock with the sand, holding the dune together