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AQA A Level Geography - PHYSICAL > ✅COASTS 3.1.3.2 - Systems and Processes > Flashcards

✅COASTS 3.1.3.2 - Systems and Processes Flashcards

1
Q

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

A

Wind- blows sediment, makes waves
Waves, Currents, Tides
Rivers
Cliff erosion- especially in areas w/ unconsolidated rock
Calving glaciers

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2
Q

How does the wind provide energy?

A

Strong winds move across the water surface, creating frictional drag. This creates orbital motion of water particles in waves.
As seabed gets shallower,orbit becomes more elliptical, higher waves, lower length and velocity, causing wave to break
Longer the fetch (distance wind blows) more powerful waves are. So waves are most powerful in storms

Winds with large fetches can transfer more energy

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3
Q

How longshore drift transports sediment?

A

sediment moves along beach due to prevailing winds,
backwash pushes it back into waves which continue to carry it in direction of prevailing wind, and so on
Can make spits and bars when coastline changes direction

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4
Q

How do waves provide energy?

A

Waves have powerful errosive energy, can destroy features

Moves sediment around, creates as well as destroys

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5
Q

How do currents provide energy?

A

Can move sediment on the sea floor

More material on and off coastline regularly, great force

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6
Q

What are rip currents?

A

Powerful underwater currents close to shore when plunging waves cause a build up of water at the top of the beach. Backwash forced under surface due to resistance of the breaking waves. Makes current. Gap in sandbar can make them faster.
In Holderness coast, rip currents hasten erosion

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7
Q

What are upwelling currents

A

Movement of cold water from deep in ocean towards the surface due to convection currents. The dense cold water replaces the warmer surface water creating currents. Vital part of global circulation pattern.

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8
Q

How do tides provide energy?

A

Moves sediment up the beach and down again, carries material

Dictates where waves can get to, location of the energy

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9
Q

What are tides?

A

Periodic rise and fall of the sea level due to gravitational pull from sun & moon. Goes from high to low twice a day.

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10
Q

What is spring tide?

A

Biggest tidal range. When sun and earth are in alignment.

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11
Q

What is neap tide?

A

Smallest tidal range. When sun and moon are at 90 degrees.

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12
Q

How does the sun provide energy?

A

It causes differences in air pressure due to different rates of heating, when then creates wind

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13
Q

How is wind energy formed?

A

By air moving between areas of different pressure

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14
Q

How are powerful winds created?

A

The greater the difference in air pressure gradient, the faster the wind speed and the more powerful

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15
Q

What are the factors impacting the size of waves?

A

Strength of the wind
The fetch
Duration of the wind

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16
Q

What are some terrestrial features affecting the coastal system?

A

Tectonics
Sediment supply
Sub aerial processes
Fluvial processes

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17
Q

What are some marine features affecting the coastal system?

A

Wave shape/size
Fetch
Wave direction
Tides
Sea level change

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18
Q

What are some human features affecting the coastal system?

A

Development
Sea defences
Tourism and recreation
Pollution
Global Warming
Conservation

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19
Q

What are some atmospheric features affecting the coastal system?

A

Winds
Temperature
Precipitation
Solar energy
Glaciation

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20
Q

How are waves formed?

A

By energy passing through the water, causing it to move in a circular motion

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21
Q

What do waves transmit?

A

Energy, not water

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22
Q

What are wind driven waves caused by?

A

Frictional drag between the wind and the surface water

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23
Q

How do waves change as they approach the shore?

A

Disturbance to the circular motion beneath the surface leads to a more horizontal movement and the wave breaks

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24
Q

What are the features of constructive waves?

A

Add material to coastline
Low wave height with long wavelength
Strong swash
Common on gently sloped beaches

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25
What are the features of destructive waves?
Tall in relation to length Remove material from coastline Common in winter Strong backwash Never reach the backshore Causes cliff face erosion Common on steep beaches
26
What are orthogonals?
Lines of wave energy
27
What are high energy coastlines like?
Rocky, ocean facing coasts where waves are powerful
28
What types of landforms tend to be on high energy coasts?
Wave cut platforms and headlands, (erosional land forms)
29
What are low energy coastlines like?
Sandy, estuarine and where waves are less powerful as the coast is sheltered (deposition)
30
How do rates of deposition and erosion compare at high energy stretches of coast?
Rate of erosion exceeds rate of deposition
31
How do rates of deposition and erosion compare at low energy stretches of coast?
Rate of deposition exceeds rate of erosion
32
What types of land forms tend to be on low energy coasts?
Beaches, spits and coastal plains
33
What are some example sources of sediment?
Rivers Cliff erosion Offshore sediment Wind
34
How do rivers act as a source of sediment?
Fluvial sediment often accounts for the vast majority of coastal sediment as it is deposited in the river mouths and estuaries, where it is reworked by waves, tides and currents
35
How does cliff erosion act as a source of sediment?
Can be extremely important locally in areas with soft rock where sand and clay are easily eroded
36
How does offshore sediment act as a source of sediment?
Can be transferred into the coastal zone by waves, tides and currents. When sea levels rose at end of last ice age, large amounts of coarse sediment was moved to South coast and formed landforms
37
How does wind act as a source of sediment?
In glacial or hot environments, wind blown sand can be deposited in coastal regions. Sand dunes are semi dynamic features at the coast that represent both accumulation of sand and potential sources
38
What might dictate the amount of sediment input into a sediment cell at any given time?
The amount of rainfall, and therefore fluvial sediment Destructive/constructive waves Season Amount of weathering
39
How does water depth affect wave refraction?
As water depth decreases, there is a reduction in wave velocity and the waves are bent towards that part of the shoreline where they are moving most slowly
40
How do headlands affect wave refraction?
The higher relief and therefore shallower water off the headlands slows the approaching wave. Wave crests converge onto headlands, increasing the energy released by the breaking wave in the bay
41
What happens to the energy where orthogonals diverge?
The energy per unit wave crest decreases
42
What are processes which shape the coast?
``` Chemical/Physical weathering Deposition Erosion Mass movement events Transfer processes ```
43
What are some marine processes?
Transportation, erosion and deposition
44
What are some sub-ariel processes?
Weathering, mass movement
45
What factors determine mass movement?
Slope, saturation, sediment size, unconsolidated or not
46
Examples of mass movement
Landslides- rain lubricates, causes sliding Rockfalls- from undercut cliffs runoff Rational slipping/ slumping- soft permeable rock slips off impermeable rock
47
What is traction?
Large particles like boulders are pushed along the sea bed by the force of water
48
What is suspension?
Small particles like silt and clay are carried along in the water
49
What is saltation?
Pebble sized particles are bounced along the sea bed by the force of the water
50
What is solution?
Soluble materials dissolve in the water and are carried along
51
How does a high energy coast affect transportation?
Small particles easily transported whilst larger and heavier material is deposited. Shingle beaches formed
52
How does a low energy coast affect transportation?
Even the smallest material is deposited forming mudflats and salt marshes
53
What is hydraulic action?
Refers to the impact on rocks of the sheer force of the water. This can exert enormous pressure upon the rock
54
What is wave quarrying?
A braking wave traps air as it hits a cliff face. The air is compressed into any gaps causing huge pressures. As the water retreats there is an explosive effect of the air pressure being released
55
What is abrasion/corrosion?
Eroded material being thrown against the rock by the waves. Also conducts erosion of wave cut platforms due to movement of material back and forth
56
What is attrition?
Rocks which are carrying out abrasion are slowly worn down into smaller and rounder particles
57
What is a concordant coastline?
Rocks on these coastlines run parallel to the sea
58
What is a discordant coastline?
Rocks on these coastlines run perpendicular to the sea
59
What is a cliff profile?
The gradient of the cliff face, responsible for whether the cliff has a steep gradient
60
What are factors influencing the rate of cliff retreat?
Rock type, geographical location and climate/season
61
What is biological weathering?
The breakdown of rocks by organic activity, such as by plant roots and water running through decaying vegetation
62
Examples of biological weathering
algae secreting chemicals promoting solution animals burrowing into cliffs
63
What is chemical weathering?
Involves chemical reactions dissolving the rocks such as through acid rain, oxidation and solution
64
Examples of chemical weathering
solution, oxidation, carbonation, hydration (water in rock causes rock to expand, weaken)
65
What is mechanical/physical weathering?
The breakup of rocks without ant chemical changes taking place, such as via freeze thaw or salt crystallisation
66
Examples of mechanical/physical weathering
freeze thaw- water enters rock, freezes, expands by about 10%, cracks rock pressure release- when overlying material is removed, rock beneath experiences a pressure relief, weakness occurs, cracking rock
67
What features do cliffs with horizontal bedding planes have?
A stable profile with a steep cliff face
68
What features do cliffs with downward tilted bedding planes have?
Very stable with slow rates of erosion as the cliff is supported by deeper running strata
69
What features do cliffs with upward tilted bedding planes have?
A cliff profile similar to the angle of the tilt and frequent mass movements when the base of the cliff is eroded
70
What features do cliffs with weathering joints have?
Very vulnerable to erosion as gravitational pull is created and cracks make them fragile
71
Positive feedback: spits
spit extends across estuary > slows river velocity > deposition > further flowing of the river
72
Positive feedback: sea level rise
SLR > more water in contact w/ice > more melting > SLR
73
Negative feedback: mass movement
cliff erosion/ undercutting > mass movement > sediment deposition at base of cliff > sediment takes time to be eroded, rate of erosion temporarily slowed
74
Negative feedback: LSD
cliff erosion from LSD > groynes installed > prevents LSD > prevents output of sediment > forms wider beach > beach absorbs more wave energy > reduces cliff erosion
75
Negative feedback: mangroves
Coastal erosion/ flooding > plant mangroves > reduced wave energy > waves deposit sediment due to larger beach > waves slow > less erosion

AQA A Level Geography - PHYSICAL (35 decks)

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