The Coastal System Flashcards

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1
Q

True or false? Coasts are a natural system

A

True

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2
Q

What are sediment stores on coasts?

A

Depositional landforms are stores of sediment.

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3
Q

What are the flows/transfers of sediments on coasts?

A

Processes such as erosion, weathering, transportation and deposition move sediment within a system

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4
Q

What are the energy inputs on coasts?

A
  • wind
  • waves
  • tides
  • currents
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5
Q

Coastal system aren’t normally in dynamic equilibrium. True or false?

A

False. They are normally in dynamic equilibrium.

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6
Q

What restores the balance in a system if a change in an output or input occurs?

A

Negative feedbacks

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7
Q

Give an example a negative feedback in a coastal system.

A

As a beach is eroded cliffs are exposed to wave attack. Sediment eroded from cliffs is then deposited and builds the beach up again.

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8
Q

Give an example of a positive feedback in a coastal system.

A

As a beach starts to form it slows waves down, causing more deposition, increasing beach size

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9
Q

What are positive feedbacks?

A

When a change in the system causes amplification of effects.

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10
Q

How is wind created?

A

By air moving from areas of high pressure to areas of low pressure.

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11
Q

Describe the pressure gradient and therefore wind strength in storms.

A

Very high making winds very strong

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12
Q

What is prevailing wind?

A

Wind that blows from the same direction

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13
Q

Prevailing wind generates higher energy waves than winds that change direction. True or false?

A

True.

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14
Q

How are waves formed?

A

Wind blowing over the sea’s surface causes friction between the wind and surface, creating a circular motion in the water

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15
Q

What are the higher and lower levels of a wave called ?

A

Wave crest and trough respectively.

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16
Q

How do you work out a wave’s wavelength?

A

The distance between two wave crests.

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17
Q

How does a wave break?

A

As the beach gets shallower friction occurs and causes the circular motion to topple, causing it to crash.

18
Q

What is a wave’s fetch?

A

The maximum distance of sea the wind has blown over in creating the waves.

19
Q

What effects a wave’s height?

A

Wind speed and fetch.

20
Q

What are the two wave types?

A

Constructive and destructive.

21
Q

What are the characteristics of a constructive waves?

A
  • low frequency (6-8 per minute)
  • low and long wave
  • strong swash
  • weak backwash
22
Q

What are the characteristics of a destructive wave?

A
  • higher frequency (10-14 per minute)
  • high and steep
  • weak swash
  • strong backwash
23
Q

What are tides?

A

The periodic rise and fall of the ocean surface

24
Q

What are tides caused by?

A

The gravitational pull of the moon and sun

25
Q

Describe how tides affect waves.

A

The position at which waves break on the beach

26
Q

Where are most landforms created and destroyed on a beach?

A

The area of land between maximum high tide and minimum low tide

27
Q

Define current

A

Current is the general flow of water in one direction

28
Q

What causes currents

A

Caused by wind OR variations in water temp. and salinity

29
Q

True or false. Currents do not move material along the coast

A

False, they do

30
Q

High energy coasts receive high inputs of energy in the form of large, powerful waves. What 3 things are they caused by?

A
  • strong winds
  • long fetch
  • steep offshore zones
31
Q

Characterise the landforms on a high energy coast.

A

Sandy coves

And rocky landforms (eg caves, stacks and arches)

32
Q

On a high energy coast what is the relationship between erosion and deposition?

A

Erosion rate > deposition rate

33
Q

On a low energy coast what is the relationship between erosion and deposition?

A

Deposition rate > erosion rate

34
Q

What landforms night you commonly find on a low energy coast?

A

Salt marshes and tidal mudflats

35
Q

What are the 4 potential causes of low energy inputs on a low energy coast?

A
  • gentle winds
  • short fetch
  • gently sloping offshore zones
  • offshore obstacles like islands or reefs, slowing waves down
36
Q

What are low energy coast waves like?

A

Small and gentle

37
Q

How can sea level rise create a source of sediment on a coast?

A

It can flood river valleys, forming estuaries, their sediment becomes part of the coastal system

38
Q

Name the 3 sediment sources (inputs) to a coast (vary your answer)

A
  • rivers bringing sediment from Inland
  • sea level rise ( explained in other card)
  • sediment eroded from cliffs
  • crushed shells of marine life
  • waves, tides & currents transporting sediment from offshore deposits
39
Q

Define sediment budget

A

Difference between amount of sediment inputs and amount of sediment outputs

40
Q

Describe what happens if a coast has a positive sediment budget

A

The coast builds outwards ( and vice versa for negative)

41
Q

Define sediment cells.

A

Lengths of coastline that are self-contained for the movement of sediment.

42
Q

Why are sediment cells closed systems?

A

Because processes In one cell don’t affect movement of sediment in another cell