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Geography > Coastal Landscapes > Flashcards

Coastal Landscapes Flashcards

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1
Q

Define a system

A

A set of interrelated objects comprising of components (stores) and processes (links) that are connected to form a working unit or unified whole

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2
Q

Name the energies present in a coastal landscape system

A
  • Kinetic (energy from wind and waves)
  • Thermal (energy from the sun)
  • Potential (position of material on slopes, material from marine deposition, weathering and mass movement from cliffs)
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3
Q

What are the inputs in a coastal landscape?

A
  • Kinetic energy from wind and waves
  • Thermal energy from heat of the sun
  • Potential energy from position of material on slopes, material from deposition, weathering and mass movement from cliffs.
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4
Q

Are coastal landscapes open or closed systems and why?

A
  • Coasts, as a whole, are open systems.
  • This is because energy AND matter can be transferred to neighbouring systems as inputs and transferred out in outputs.
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5
Q

Give examples of outputs in a coastal system

A
  • Marine and wind erosion from beaches.
  • Weathering from rock surface
  • Evaporation
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6
Q

What do processes consist of (+give an example for each)

A

Stores and flows.

  • Stores: beach and nearshore sediment accumulations
  • Flows (transfers): movement of sediment along a beach by longshore drift.
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7
Q

Define sediment cell

A
  • A stretch of coastline and it’s associated nearshore area within which the movement of coarse sediment, sand and shingle are largely self contained.
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8
Q

Are sediment cells considered open or closed systems?

A
  • Closed system.
    It is thought that no sediment is transferred from one cell to another.
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9
Q

How many large sediment cells are the around the coast of England and Wales

A

11

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10
Q

What are sediment boundaries determined by and give a geographical example.

A
  • Sediment cell boundaries are determined by topography and shape of the coastline.
  • Example: Lands end acts as a large barrier against sediment transfer.
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11
Q

Explain why it is unlikely that sediment cells are completely closed systems

A

It is unlikely to be completely closed due to variations in wind direction and the presence of tidal currents.

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12
Q

What are the 5 potential physical factor influences on coastal landscapes?

A
  • Winds
  • Waves
  • Tides
  • Geology
  • Patterns of ocean currents
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13
Q

In what ways do winds influence coastal landscapes?

A
  • Winds act as a source of energy for wave action - influencing erosion and transport.
    For example, winds blowing at an oblique angle towards the coast makes the resultant waves obliquely approach too - generating longshore drift.
  • Can contribute to aeolian processes
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14
Q

How is wave energy generated?

A

Generated by the frictional drag of winds moving across the ocean surface

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15
Q

How does wind speed and fetch affect waves?

A

The higher the wind speed and longer the fetch, the longer the waves and higher the energy.

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16
Q

What energy do waves possess?

A
  • Potential energy due to position above wave trough
  • Kinetic energy caused by the motion of water molecules within the wave.
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17
Q

Waves move water forwards, true or false?

A

False!

Waves impart a circular motion to the individual water molecules.

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18
Q

What is the formula for wave energy?

A
  • P = H²T
  • P is the energy of the wavefront (kw/m)
  • H is the wave height (m)
  • T is the time interval between wave crests (s)
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19
Q

Outline how waves break

A
  • Waves move into shallow water (depth of half the wavelength)
  • The deepest circling molecules come into contact with the ocean floor
  • Friction is produced which changes the speed, direction and strength. As a result, waves slow down as they drag - decreasing the wave length so successive waves begin to bunch up.
  • The deepest part of the wave slows down more than the crest so it steepens, advances ahead of the base and topples over - breaking.
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20
Q

Outline the process of swash and backwash.

A
  • As a wave breaks, there is a significant forward movement of water and energy.
  • As the wave breaks, water moves up the beach as swash.
  • The swash decreases in energy and speed as it advances up the beach due to friction and uphill gradient.
  • When there is no more available energy to move forward, the water is drawn back down the beach as backwash. Energy for backwash comes from gravity.
  • Backwash occurs perpendicular to the coastline, down the steepest slow angle.
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21
Q

List the features of a constructive wave

A
  • Tend to be low in height
  • Long wavelength
  • Low frequency (6-8 p/m)
  • Break by spilling forward
  • Swash exceeds backwash
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22
Q

List the features of a destructive wave

A
  • Greater height
  • Shorter wavelength
  • Higher frequency (12-14)
  • Break by plunging downwards.
  • Backwash exceeds swash
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23
Q

Why is swash energy exceeding backwash energy in constructive waves?

A

As they have long wavelengths, backwash returns to the sea before the next wave breaks.
From this, the next swash movement is uninterrupted and maintains energy.

24
Q

Why does backwash exceed swash in destructive waves?

A

As waves plunge downwards, there is little forward transfer of energy to move water up steeply sloping beaches.
The steep beach slows down swash energy so it doesn’t travel far.
The short wavelength means the next swash is slowed by the returning backwash.

25
Q

What is the relationship between gradient and wave type?

A
  • High energy waves (winter months usually) tend to remove material from the top of the beach, transporting it to the offshore zone and reducing beach gradient.
  • Low energy waves (typically summer months) steepens the beach profile .
26
Q

Anatomy of a wave (bullet points)

A
  • The highest surface part of a wave is the crest
  • The lowest part is the trough
  • The vertical distance between the crest and trough is wave height
  • Horizontal distance between two adjacent crests is the wave length.
27
Q

What are swell waves?

A

Waves formed in open oceans that travel huge distances from the place they were formed.

28
Q

Compare a swell wave and storm wave

A
  • Swell waves have a….
    : Formed in open oceans
    : Long wave length
    : Wave period of 20 s
  • Storm waves
    : Locally generated
    : Short wavelength
    : Greater height
    : Shorter wave period
29
Q

Define tides

A

Tides are the periodic rise and fall of the sea surface produced by the gravitational pull of the moon (and the sun).

30
Q

How is high and low tide formed?

A
  • The moon pulls water towards it, creating a high tide - and a compensatory bulge on the other side of the earth.
  • In areas between these two bulges, there will be a low tide
31
Q

Differentiate between a neap tide and spring tide

A
  • A neap tide is where there is a low tidal range
  • A spring tide is where there is a high tidal range
32
Q

How often do neap or spring tides occur?

A

Twice monthly

33
Q

How is a spring tide formed?

A
  • When the moon, sun and earth are all aligned, gravitational pull is at it’s strongest and produces the highest tides (spring tides)
34
Q

How is a neap tide formed?

A
  • When the moon and sun are at right angles to each other, so the gravitational pull is therefore at it’s weakest - producing the lowest tides (neap tides)
35
Q

How does tidal range influence landscapes?

A
  • In enclosed areas (Mediterranean), tidal ranges are low so wave action is restricted to a narrow area of land.
  • In areas where the coast is funneled (River Severn), tidal range is high.

THEREFORE.
Tidal range influences where wave action occurs, weathering processes on exposed land.

36
Q

What are the two subsections of geology?

A
  • Lithology
  • Structure
37
Q

Define lithology in relation to geology

A

Lithology describes the physical and chemical composition of rocks.

38
Q

How does lithology of rocks influence coastal landscape?

A
  • Rocks with weak lithology (clay) have little resistance to erosion, weathering and mass movements.
    This is due to the bonds between particles being weak.
  • Rocks with strong lithology (basalt) are more resistant to erosion due to being formed of stronger bonds and dense interlocking crystals. They will form prominent coastal features such as headlands.
  • Chalk is soluble in weak acids so is vulnerable to chemical weathering.
39
Q

Define structure in relation to geology

A

Structure is the properties of individual rock types such as jointing, bedding and faulting - also including the permeability of the rock.

40
Q

Differentiate between primary permeability and secondary permeability in structure (geology)

A
  • Primary permeability:
    Porous rocks (chalk) pores separate the mineral particles and absorb/store water.
  • Secondary permeability
    Limestone is secondary permeable as water seeps into many joints and these are enlarged by solution.
41
Q

How does rock structure influence coastal landscapes?

A
  • Influence on a regional scale.
    Uniform or parallel outcrops produce straight and concordant coastlines.
    Rocks at right angles to the coast create discordant planforms.

Structure also alters cliff profiles.
Structure determines the angle of dip of rocks.

42
Q

What are currents

A

A body of water moving in a definite direction

43
Q

How are rip currents formed?

A

Formed by either tidal motion or waves breaking at right angles to the shore.
Cellular circulation is generated by differences in wave heights parallel to the shore - water from the top of breaking waves travel further up the shore and returns through the adjacent area where lower wave height shave broken.

44
Q

In what ways do rip currents influence coastal landscapes?

A
  • Affect sediment transport
  • Modify the shore profile by creating cusps - perpetuating the rip current.
45
Q
A
46
Q

CURRENTS FLASGCARD

A
47
Q

What are the three sources of sediment in coastal landscapes?

A
  • Terrestrial
  • Offshore
  • Human
48
Q

What is an example of a terrestrial sediment supply to the coast?

A

Rivers

49
Q

Sediment delivery to the shoreline is intermittent, occurring mostly during river floods (terrestrial input), true or false?

A

True

50
Q

What is the origin of terrestrial sediment?

A

The erosion of inland areas by water, wind, ice AND subaerial processes such as weathering and mass movement

51
Q

Where can terrestrial sediment come from (list)

A
  • River deposition
  • Erosion by water, wind and ice
  • Sub-aerial processes such as weathering and mass movement
  • Wave erosion
  • Longshore drift from one coastal area to another
52
Q

What % does the erosion of weak cliffs in high energy environments contribute to sediment budget?

A

70%

53
Q

How is coastal sediment supplied from offshore?

A
  • Constructive waves bring sediment to the shore from offshore and deposit it (marine deposition)
  • Tides and currents also contribute to marine deposition
  • Winds blow sediment from exposed sand bars, sand dunes or other beaches
54
Q

Why is sediment transported by wind usually fine sand?

A

Aeolian material is fine as wind has LESS energy than water so it cannot transport large particles

55
Q

How does human sources of sediment contribute to the sediment budget?

A
  • Management strategies such as beach renourishment includes bringing sediment from elsewhere to restore equilibrium when the sediment budget is in deficit.
56
Q

What are two ways in which humans conduct beach nourishment?

A
  • Sediment can be brought in by a lorry and dumped on the beach to be spread out by bulldozers
  • Sand and water are pumped onshore by pipeline from offshore - low bunds hold the mixture in place as water drains away and leaves the sediment behind.

Geography (36 decks)

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