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Geography Paper 1 > Coastal landscapes and Change > Flashcards

Coastal landscapes and Change Flashcards

1
Q

What can the coast be considered, and why?

A

An open system, as it receives inputs from outside the system and transfers outputs away from the coast and into other systems

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2
Q

What other systems can coast’s outputs be transferred to?

A

Terrestrial, atmospheric or oceanic
- Can include the rock, water and carbon cycles

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3
Q

What are sediment cells?

A
  • These are the sections that coasts are split into
  • They are typically considered a closed system in terms of sediment
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4
Q

What are sources in sediment cells?

A

Where the sediment originates from (e.g cliffs, offshore bars)

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5
Q

What are through flows in sediment cells?

A

The movement of sediment along the shore through longshore drift

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6
Q

What are sinks in sediment cells?

A

Locations where deposition of sediment dominates (e.g spits, beaches)

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7
Q

How does the coastal system operate under normal conditions?

A
  • It operates in a state of dynamic equilibrium
  • Dynamic equilibrium in a sediment cell is where inputs and outputs of sediment are in a constant state of change, but remain in balance.
  • Physical and human actions can change this equilibrium
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8
Q

Describe the negative feedback loop in coastal systems?

A
  • Lessens any change which has occurred within the system
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9
Q

Give an example of a negative feedback loop?

A

A storm could erode a large amout of a beach, taking the beach out of dynamic equilibrium as there is a larger input of sediment into the system than output:

  • Destructive waves from storm lose their energy and deposit excess sediment as an offshore bar
  • The bar dissipates the waves energy, protecting the beach from further erosion
  • Over time the bar gets eroded instead of the bach
  • Once the bar has gone normal conditions ensue and the system goes back to dynamic equilibrium
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10
Q

Describe the positive feedback loop in coastal systems:

A
  • This exaggerates the change, making the system more unstable and taking it away from dynamic equilibrium
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11
Q

Give an example of a positive feedback loop?

A
  • People walking over sand dunes desroys vegetation growing there and causes erosion
  • As the roots from the vegetation have been holding the sand dunes together, damaging the vegetation makes the sand dunes more susceptible to erosion. This increases the rate of erosion
  • Eventually the sand dunes will be completely eroded leaving more of the beach open to erosion, taking the beach further away from dynamic equilibrium
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12
Q

What is the littoral zone and why is it constantly changing and varying?

A
  • The area of the coast where land is subject to wave action.

It is constantly changing and varies due to:

  • Short-term factors like tides and storm surges
  • Long-term factors like changes in sea level and climate change
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13
Q

What are the subzones within the littoral zone?

A

Backshore- area above high tide level and only affected by exceptionally high tides

Foreshore- this is land where most wave processes occur

Offshore- the open sea

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14
Q

What does Valentine’s Classification describe?

A

The range of coastlines that can occur

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15
Q

Why might a coastline be advancing?

A
  • Due to the land emerging or deposition being the prominent process
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16
Q

Why might a coastline be retreating?

A
  • Due to the land submerging or erosion becoming the prominent process
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17
Q

What might be the cause of emergent or submergent coastlines?

A

Post-glacial adjustment (the land wobbles as the glacier above it melts, causing isostatic sea level change

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18
Q

What are the main processes of erosion?

A

Corrasion
Abrasion
Attrition
Hydraulic Action
Corrosion
Wave Quarrying

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19
Q

What is corrasion?

A
  • Sand and pebbles are picked up by the sea from an offshore sediment sink or temporal store and hurled against the cliffs at high tide
  • This causes the cliffs to be eroded
  • The shape, size, weight and quantity of sediment picked up, as well as the wave speed, affects the erosive power of this process
20
Q

What is abrasion?

A
  • This is the process where sediment is moved along the shoreline, causing it to be worn down over time.
21
Q

What is attrition?

A
  • Wave action causes rocks and pebbles to hit against each other, wearing each other down and so becoming round and eventually smaller.
  • Attrition is an erosive process within the coastal environment, but has little to no effect on erosion of the coastline itself
22
Q

What is hydraulic action?

A
  • As a wave crashes onto a rock or cliff face, air is forced into cracks, joints and faults within the rock.
  • The high pressure causes the cracks to force apart and widen when the wave retreats and the air expands.
  • Over time this causes the rock to fracture.
  • Bubbles fond within the water may implode under the high pressure, creating tiny jets of water that over time erode the rock- this process is called cavitation
23
Q

What is cavitation?

A

Bubbles found within water may implode under the high pressure, creating tiny jets of water that over time erode rock

24
Q

What is corrosion?

A
  • Also known as solution
  • The mildy acidic seawater can cause alkaline rock to be eroded and is very similar to the process of carbonation weathering
25
Q

What is wave quarrying?

A
  • This is when breaking waves that hit the cliff face exert a pressure up to 30 tonnes per m².
  • It is very similar to hydraulic action but acts with significantly more pressure to directly pull away rocks from a cliff face or remove smaller weathered fragments.
  • The force of the breaking wave hammers the rocks surface, shaking and weakening it and leaving it open to attack from hydraulic action and abrasion
26
Q

When are erosion rates the highest?

A
  • Waves are high and have a long fetch
  • Waves approach the coast perpendicular to the cliff
  • At high tide- waves travel higher up the cliff so a bigger area of cliff face is able to be eroded
  • Heavy rainfall occurs- water percolates through permeable rock, weakening the cliff
  • In winter- destructive waves are the largest and most destructive during winter
27
Q

What is the resistance of a rock influenced by?

A

Whether rocks are clastic or crystalline
- sedimentary rocks like sandstone are clastic as they are made up of cemented sediment particles, therefore are vulnerable to erosion, whereas igneous and metamorphic rocks are made up of interlocking crystals, making them more resistant

The amount of cracks, fractures and fissures
- The more weaknesses there are in the rock the more open it is to erosional processes, especially hydraulic action

The lithology of the rock
- The type of rock and the conditions of the rock’s creation directly affects its vulnerability to erosion

28
Q

What are examples of igneous rock?

A

Granite
Basaslt

29
Q

What are examples of metamorphic rock?

A

Slate
Schist
Marble

30
Q

What are examples of sedimentary rock?

A

Limestone

31
Q

What is the rate of erosion of igneous rock?

A

Very slow
<0.1cm/year

32
Q

What is the rate of erosion of metamorphic rock?

A

Slow
0.1-0.3cm/year

33
Q

What is the rate of erosion of sedimentary rock?

A

Very fast
0.5-10cm/year

34
Q

What is the structure of igneous rock?

A

Interlocking crystals which allow for high resistance

35
Q

What is the structure of metamorphic rock?

A

Crystal all orientated in the same direction

36
Q

What is the structure of sedimentary rock?

A

Lots of fractures and bedding planes making them weak

37
Q

Where do caves, arches, stacks and stumps form?

A

Pinnacle headlands

38
Q

Describe the formation of caves, arches, stacks and stumps:

A
  • Marine erosion widens faults in the base of the headland, widening over time to create a cave
  • The cave will widen due to both marine erosion and sub-aerial processes, eroding through to the other side of the headland to create an arch.
  • The arch continues to widen until it is unable to support itself, falling under its own weight through mass movement,
  • This leaves a stack as one side of the arch becomes detached from the mainland
  • With marine erosion attacking the base of the stack, eventually it will collapse into a stump
39
Q

Describe the formation of wave-cut notches and platforms:

A
  • Marine erosion attacks the base of a cliff, creating a notch of eroded material between high tide height and low tide height
  • As the notch becomes deeper (and sub-aerial weathering weakens the cliff from the top) the cliff becomes unstable and falls under its own weight through mass movement.
  • This leaves behind a platform of the unaffected cliff base beneath the wave-cut notch
40
Q

What are retreating cliffs?

A

Through the process of repeat wave-cut notches and platforms, new cliff faces are created, whilst the land retreats

41
Q

What are blowholes?

A
  • A combination of two features: a pot hole on top of a cliff, creating by chemical weathering, and a cave, formed by marine erosion
  • As the cave erodes deeper into the cliff face and the pothole deepens, they may meet.
  • In this case, a channel is created for incoming waves to travel into and up the cliff face (occasionally water splashes out of the top of the blowhole)
42
Q

What is Longshore Drift?

A
  • How sediment is predominantly transported along the coast
  • It transports sediment along the beach and between sediment cells
43
Q

Describe the process of longshore drift:

A
  • Waves hit the beach at an angle determined by the direction of the prevailing wind
  • The waves push sediment in this direction and up the beach in the swash
  • Due to gravity, the wave then carries sediment back down the beach in the backwash
  • This moves sediment along the beach over time
44
Q

What are other transportation processes?

A

Traction
- large, heavy sediment rolls along the sea bed, being pushed by currents

Saltation
- Smaller sediment bounces along the sea bed, being pushed by currents

Suspension
- Small sediment is carried within the water column (a body of water)

Solution
- Dissolved material is carried within the water

45
Q

What does the impact of transportation depend on?

A

The severity of the angle that waves travel onto land

46
Q

What does swash-aligned mean?

A

Wave crests approach parallel to the coast so there is limited longshore drift

Sediment doesn’t travel far up the beach

47
Q

What does drift-aligned mean?

A

Waves approach at a significant angle, so longshore drift causes the sediment to travel far up the beach

Geography Paper 1 (6 decks)

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