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A-Level Geography > A-Level Geography: Coastal Landscapes and Change EQ2 > Flashcards

A-Level Geography: Coastal Landscapes and Change EQ2 Flashcards

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1
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What are the two main types of waves?

A

Constructive and destructive waves are the two main types of waves. The characteristics of these waves are described below.

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2
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What are constructive waves?

A
  • Happen at a low frequency (6-9 waves per minute).
  • Over time, constructive waves will form gently sloping beaches.
  • Constructive waves deposit material on coasts because the backwash is less powerful than the swash.
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3
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What are destructive waves?

A
  • Happen at a high frequency (10-15 waves per minute).
  • Steep and high, with a circular motion so waves break at a greater height.
    This causes the wave to ‘plunge’ and travel a shorter distance along the beach.
  • Destructive waves remove material from coasts because the swash is less powerful than the backwash.
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4
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

How does hydraulic pressure influence coastlines?

A
  • Hydraulic power causes the breakdown of cliffs due to the force of the water being compressed into the cracks of the rock.
  • The repeated action of the water forced in and out of the cracks in the rock leads to the breakdown of the surrounding cliff.
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5
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

How does corrosion influence coastlines?

A

Corrosion happens when there is a chemical reaction between the seawater (which contains a weak acid) and susceptible rocks like limestone.

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6
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

How does attrition influence coastlines?

A

Attrition is where pieces of bedload (material carried in the water) are hit against one another. This causes them to break apart and become smaller and more rounded.

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7
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

How does abrasion influence coastlines?

A

Abrasion is where pieces of rock are picked up by waves and hit against the bed, the beach or cliffs. This wears them away over time.

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8
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What are the reasons behind the resistance of a rock?

A
  • Clastic or crystalline
  • Amount of cracks or fissures
  • Rock lithology
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9
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

Why is whether a rock is clastic or crystalline important to vulnerability?

A

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 to erosion.

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10
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

Why is whether the amount of cracks, fractures and fissures important to vulnerability?

A

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.

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11
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

Why is whether lithology important to vulnerability?

A
  • Igneous rocks - has interlocking crystals which allow for high resistance making erosion the slowest of the three.
  • Metamorphic rocks - has crystals all orientated in the same direction making rates of erosion slow.
  • Sedimentary rocks - has lots of fractures and bedding planes which makes them weak and erode the fastest.
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12
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What are the rates of erosion between the main lithological structures?

A
  • Igneous rocks - less than 0.1cm/year
  • Metamorphic rocks - 0.1 - 0.3cm/year
  • Sedimentary rocks - 0.5 - 10cm/year
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13
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What are the main erosional landforms?

A
  • Cave, Arches, Stacks and Stumps

- Wave-cut notch and platform

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14
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What is the sequence behind 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, creating an arch.
  • The arch continues to widen until it is unable to support itself, falling under its own weight through mass movement, leaving a stack as one side of the arch becomes detached from the mainland.
  • With marine erosion attacking the base of the stack, eventually, the stack will collapse into a stump.
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15
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

What is the sequence behind 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 face becomes unstable and falls under its own weight through a mass movement.
  • This leaves behind a platform of the unaffected cliff base beneath the wave-cut notch.
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16
Q

2B.4 Marine erosion creates distinctive coastal landforms and contributes to coastal landscapes.

When are erosion rates highest?

A
  • When waves are high and have a long fetch (the distance the wind has travelled over the wave).
  • When waves approach the coast perpendicular to the cliff.
  • At high tide, waves travel higher up the cliff so a bigger area of the cliff face is able to be eroded.
  • When heavy rainfall occurs - water percolates through permeable rock, weakening cliff.
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17
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is meant by traction?

A

When rocks and boulders are rolled along the sea bed.

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18
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is meant by saltation?

A

The movement of sand or other sediments by short jumps and bounces is caused by wind or water.

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19
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is meant by suspension?

A

When light sediment travels above the sea bed such as silt or clay.

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20
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is meant by solution?

A

Sediment carried that is dissolved by the water.

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21
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is longshore drift (LSD)?

A

Movement of sediment in a zig-zag pattern up and down the shore with swash and backwash resulting in an overall direction along the coast.

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22
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is meant by the current?

A

The flow of water in a particular direction is affected by water density, temperature or salinity.

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23
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are tides?

A

The regular rise and fall of the ocean’s surface are influenced by the moon’s gravity pulling on earth.

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24
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are the main factors behind the creation of depositional landforms?

A
  • These are landforms created by the deposition of sediment when waves run out of energy to carry sediment.
  • This can be caused by factors including wind levels falling, groynes, refraction, and friction.
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25
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is the process behind longshore drift (LSD)?

A
  • It transports sediment along the beach and between sediment cells.
  • 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.
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26
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What determines the effectiveness of longshore drift (LSD)?

A
  • Swash-aligned - wave crests approach parallel to coast so there is limited longshore drift. Sediment doesn’t travel up the beach far.
  • Drift-aligned - waves approach at a significant angle, so longshore drift causes the sediment to travel far up the beach.
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27
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What determines the likelihood of deposition?

A
  • Gravity settling - the wave’s energy becomes very low and so heavy rocks and boulders are deposited followed by the next heaviest sediment.
  • Flocculation - clay particles clump together due to chemical attraction and then sink due to their high density.
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28
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are the main depositional landforms?

A
  • Spits
  • Bars
  • Tombolo
  • Sand dunes
  • Beaches
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29
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are spits?

A
  • A linear ridge of sand from deposited materials formed on drift aligned coastlines usually by the mouth of a river.
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30
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

How is a spit created?

A
  • Longshore drift occurs along the coastline but as the waves lose energy (normally due to going into a sheltered area such as behind a headland) they deposit their sediment.
  • Over time this creates a spit. Periodically, the prevailing wind will change direction causing a hook to appear.
  • Over time, the sheltered area behind a spit can turn into a salt marsh. The length of a spit is influenced by surrounding currents or rivers.
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31
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are bars? How are they formed?

A

A spit that, over time, crosses a bay and links up two sections of the coast (the water within the bay is called a lagoon).

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32
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a tombolo? How are they formed?

A

A tombolo is a bar or beach that connects the mainland to an offshore island and is formed due to wave refraction off the coastal island reducing wave velocity, leading to deposition of sediments. They may be covered at high tide if they are low lying.

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33
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a sand dune? How are they formed?

A

Sand dunes occur when prevailing winds blow sediment to the back of the beach and therefore the formation of dunes requires large quantities of sand and a large tidal range. This allows the sand to dry, so that it is light enough to be picked up and carried by the wind to the back of the beach. The dunes develop as a process of a vegetation succession

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34
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is unconsolidated sediment?

A

A sediment that is loosely arranged or unstratified, or whose particles are not cemented together.

35
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

Why are depositional landforms unstable by nature?

A

Depositional landforms consist of unconsolidated sediment and are therefore vulnerable to change. During major storms, large amounts of sediment can be eroded or transported elsewhere removing a landform from one region of the sediment cell. Depositional landforms depend on a continuous supply of sediment to balance erosion, which may see some landforms changed as their dynamic equilibrium shifts.

36
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is plant succession? How does it help stabilise coastal landscapes?

A

On coasts where there is a supply of sediment and deposition occurs, pioneer plants begin to grow in bare mud and sand. Due to the salty soil conditions, only certain plants can grow there. As more deposition occurs and the vegetation dies and releases nutrients into the sand this reduces the saltiness of the soil which means different plants can start growing there.

37
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

How do plants help stabilise sediments?

A
  • It helps catch and stores sediment.
  • It holds together sediment and rocks such as on cliffs.
  • It protects the cliff from sub-aerial processes such as weathering and mass movement.
38
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is an example of a pioneer plant and why?

A
  • Marram grass is a very good example of a pioneer plant. It is tough and flexible, so can cope when being blasted with sand.
  • It has adapted to reduce water loss through transpiration.
  • Their roots grow up to 3 metres deep and can tolerate temperatures of up to 60C.
  • Is a Xerophyte.
39
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are the two main plant types that grow in different coastal environments?

A
  • Xerophytes - plants that are tolerant of dry conditions.

- Halophytes (or brackish) - plants that are tolerant of salty conditions.

40
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What type of system is the coast considered?

A

It can be considered an open system as it receives inputs from outside the system and transfers outputs away from the coast and into other systems. These systems may be terrestrial, atmospheric or oceanic and can include the rock, water and carbon cycles.

41
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

How many sediment cells are in England and Wales?

A

There are 11 sediment cells.

42
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a sediment cell?

A

A sediment cell is a largely self-contained stretch of coastline. They are regarded as closed systems as sediment is not usually transferred from one to the other. However, in reality, some sediment does get transferred between neighbouring cells.

43
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a sediment source?

A

Where sediment has come from on the coastline; the sources (rivers, cliffs) and material moved from offshore (coastal cliff erosion).

44
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is the sediment transfers?

A

It refers to the movement of sediment along the shore via longshore drift (LSD).

45
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a sediment sink?

A

The location where deposition of sediment dominates (e.g. spits and beaches).

46
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are examples of sediment sources?

A

Cliff erosion, fluvial sediment, offshore bars and eroding depositional features e.g beaches, spits and dunes.

47
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are examples of sediment transfers?

A

Currents, saltation and longshore drift. These types of transfers transport sediment to sinks which are long-term stores that move the sediment from the transfer processes within the cell.

48
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are examples of sediment sinks?

A

Estuary, offshore bar or bank and submarine canyons.

49
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is meant by dynamic equilibrium?

A

Dynamic equilibrium in a sediment cell is where input and outputs of sediment are in a constant state of change but remain in balance.

50
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What are two reasons why sediment cells can be seen as closed systems?

A
  • Sediment cells can be viewed as closed systems because the inputs received are from within the cell and from the land and not from other cells.
  • Another reason why sediment cells can be seen as closed systems is that sediment is deposited in these outputs which means they still remain geographically part of the cell, therefore no components require interactions with any other cell or anything outside of the coastal sediment and can therefore be viewed as a closed system.
51
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is the sediment cell budget?

A

A sediment budget is a balance between changes in the volume of sediment held within the system and the volume of sediment entering or leaving the system.

52
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a positive and negative sediment cell budget?

A

A positive budget is when there are more inputs than outputs to the system and a negative budget is when outputs are higher than inputs.

53
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

Give one way the sediment cell budget can alter?

A

The budget will alter when humans manage a coastline eg: reduce the transfer of sediment using groynes, or increase the amount of sediment through beach nourishment.

54
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

Why is a sediment cell rarely in equilibrium?

A
  • Human intervention e.g. beach replenishment.
  • Tectonic energy e.g. tsunamis and storm surges.
  • Cliff collapse.
55
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a negative feedback loop?

A

This lessens any change which has occurred within the system. For example, a storm could erode a large amount of a beach, taking the beach out of dynamic equilibrium as there is a larger input of sediment into the system than output.

56
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

What is a positive feedback loop?

A

This exaggerates the change making the system more unstable and taking it away from dynamic equilibrium.

57
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

How will a negative feedback loop balance the excess sediment to a state of dynamic equilibrium?

A
  • When the destructive waves from the storm lose their energy excess sediment is deposited as an offshore bar.
  • The bar dissipates the wave’s energy which protects the beach from further erosion.
  • Over time the bar gets eroded instead of the beach.
  • Once the bar has gone normal conditions ensue and the system goes back to dynamic equilibrium.
58
Q

2B.5 Sediment transport and deposition create distinctive landforms and contribute to coastal landscapes.

How will a positive feedback loop create instability in dynamic equilibrium?

A
  • People walking over sand dunes destroys 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.
59
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is weathering?

A

Weathering is the breakdown of rocks (mechanical, biological or chemical) over time, leading to the transfer of material into the littoral zone, where it becomes an input to sediment cells.

60
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is mechanical weathering?

A

The breakdown of rocks due to exertion of physical forces without any chemical changes taking place.

61
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is chemical weathering?

A

The breakdown of rocks through chemical reactions. There are different types of chemical weathering.

62
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is biological weathering?

A

The breakdown of rocks due to the actions of plants, bacteria and animals.

63
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What are the main types of mechanical weathering?

A
  • Freeze-thaw
  • Salt Crystallisation
  • Wetting and Drying
64
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What are the main types of chemical weathering?

A
  • Carbonation
  • Oxidation
  • Solution
65
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What are the main types of biological weathering?

A
  • Plant roots
  • Birds
  • Seaweed Acids
66
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does freeze-thaw cause the breakdown of rocks?

A

Water enters cracks in rocks and then the water freezes overnight during the winter. As it freezes, water expands by around 10% in volume which increases the pressure acting on a rock, causing cracks to develop. Over time these cracks grow, weakening the cliff making it more vulnerable to other processes of erosion.

67
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does salt crystallisation cause the breakdown of rocks?

A

As seawater evaporates, salt is left behind. Salt crystals will grow over time, exerting pressure on the rock, which forces the cracks to widen. Salt can also corrode ferrous (materials that contains iron) rock due to chemical reactions.

68
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does wetting and drying cause the breakdown of rocks?

A

Rocks such as clay expand when wet and then contract again when they are drying. The frequent cycles of wetting and drying at the coast can cause these rocks and cliffs to break up.

69
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does carbonation cause the breakdown of rocks?

A

Rainwater absorbs CO2 from the air to create a weak carbonic acid which then reacts with calcium carbonate in rocks to form calcium bicarbonate which can then be easily dissolved. Acid rain reacts with limestone to form calcium bicarbonate, which is then easily dissolved allowing erosion.

70
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does oxidation cause the breakdown of rocks?

A

When minerals become exposed to the air through cracks and fissures, the mineral will become oxidised which will increase its volume (contributing to mechanical weathering), causing the rock to crumble. The most common oxidation within rocks is iron minerals becoming iron oxide, turning the rock rusty orange after being exposed to the air.

71
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does solution cause the breakdown of rocks?

A

When rock minerals such as rock salt are dissolved.

72
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How do plant roots cause the breakdown of rocks?

A

Roots of plants grow into the cracks of rocks, which exerts pressure, eventually splitting the rocks.

73
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How do birds cause the breakdown of rocks?

A

Some birds such as Puffins dig burrows into cliffs weakening them and making erosion more likely.

74
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does seaweed acids cause the breakdown of rocks?

A

Some seaweeds contain pockets of sulphuric acid, which if hit against a rock or cliff face, the acid will dissolve some of the rock’s minerals. (e.g. Kelp)

75
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is weatherings contribution to coastal recession?

A

Weakens rock to make mass movement more common. Some strata more vulnerable than others, weathering rates generally very slow. so doesn’t contribute hugely.

76
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is mass movement?

A

The downslope movement of rock and soil. Umbrella term for a wide range of specific movements including rockfall and rotational slide.

77
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What are the two types of mass movement?

A

A slide and a flow. For a slide, sediment keeps its same place within the whole material, simply moves downhill. However, for a flow, all the material flows downs and mixes.

78
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What do slides include?

A
  • Rock falls - Occur on sloped cliffs (over 40 degrees ) when exposed to mechanical weathering.
  • Rockslides - Water between joints and bedding planes (which are parallel to the cliff face) can reduce friction and lead to more sliding.
  • Slumps - Occurs when the soil is saturated with water, causing a rotation movement of soft materials (such as clay and sand) forming rotational scars and terraced cliff profiles.
79
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What do flows include?

A
  • Soil creep - The slowest but a continuous form of mass movement involving the movement of soil particles downhill.
  • Solifluction - Occurs mainly in tundra areas where the land is frozen. As the top layers thaw during summer (but the lower layers still stay frozen due to permafrost) the surface layers flow over the frozen layers.
  • Mudflows - An increase in the water content of soil can reduce friction, leading to earth and mud flowing over underlying bedrock.
80
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

How does weather influence vulnerability to sub-aerial processes?

A

Temperature and climate can influence the prominent process of weathering. In colder climates, mechanical weathering is more common whereas, in warmer climates, chemical weathering is more common.

81
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is blockfall?

A

When undercutting leads to large falls, Rockfall is common on coasts where blocks of rock are dislodged by mechanical weathering and hydraulic action takes place.

82
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is a distinctive landform created by blockfall?

A
  • Angular blockfall accumulates at cliff foot to form a scree slope, a heaping mound of material. The angle of 30-40degrees. Undercutting and wave-cut notches often lead to this.
  • April 2013- large blockfall in St Oswald’s bay on the south Dorset coast. 80m detached overnight. 30m scree slope at the base and protects from cliff erosion for a decade or more.
83
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is a rotational slide?

A

Occurs along curved faulted surfaces. Huge masses rotate downslope over days or years, Often occurring at water-saturated cliffs.

84
Q

2B.6 Subaerial processes of mass movement and weathering influence coastal landforms and contribute to coastal landscapes.

What is a distinctive landform created by rotational slides?

A

Exposes rotational scar. Fresh, curved, unweakened and unvegetated on a cliff face. Detached slope section often forms beach or terraced cliff profile. Vegetation is often on top of a slump.

A-Level Geography (34 decks)

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