3. Rocks and Weathering Flashcards

9696 - Cambridge AS Geography

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1
Q

Plate Tectonics

A

The theory that Earth’s lithosphere (upper mantle and crust) is divided into rigid plates that move horizontally across the plastic asthenosphere below.

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2
Q

Size and Composition of Plates

A

Plates vary in size and are composed of continental crust (silica-rich) and oceanic crust (basalt-rich).

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3
Q

Movement of Plates

A

Plates move slowly (a few centimeters per year) in different directions, driven by mantle convection currents.

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4
Q

Global Patterns of Plate Movement

A

Seven major plates and numerous smaller plates make up the Earth’s surface, with distinct boundaries.

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5
Q

Divergent (Constructive) Boundaries

A

Plates move apart, allowing upwelling of mantle material to form new oceanic crust.

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6
Q

Key Features of Constructive Plate Boundaries

A

Mid-ocean ridges, volcanic activity, and rift valleys.

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7
Q

Conservative Boundaries

A

Plates slide past each other horizontally, creating friction and potential earthquakes.

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8
Q

Key Features of Conservative Plate Boundaries

A

Transform faults and mountain ranges.

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9
Q

Convergent (Destructive) Boundaries

A

Plates collide, pushing one plate under the other (subduction).

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10
Q

Subduction Zone Characteristics

A

Oceanic crust dives under continental crust or another oceanic plate, causing earthquakes, volcanic activity, and trench formation.

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11
Q

Seafloor Spreading

A

Molten rock rises at divergent boundaries, solidifying and creating new ocean floor, pushing continents apart.

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12
Q

Subduction

A

Oceanic crust sinks beneath another plate, recycling crust back into the mantle and creating deep ocean trenches.

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13
Q

Landforms of Subduction

A

Ocean trenches, volcanic island arcs (e.g., Japan).

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14
Q

Fold Mountain Building

A

Convergence can crumple and fold sediments at plate boundaries, forming mountain ranges.

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15
Q

Examples of Fold Mountains

A

The Himalayas, Alps, and Appalachians are all examples of fold mountains.

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16
Q

Ocean Ridges

A

Long, underwater mountain ranges marking divergent boundaries with volcanic activity.

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17
Q

Ocean Trenches

A

Deep, elongated depressions in the ocean floor marking convergent boundaries (subduction zones).

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18
Q

Volcanic Island Arcs

A

Chains of volcanic islands formed due to subduction, often parallel to trenches.

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19
Q

Weathering

A

The breakdown and decomposition of rocks and minerals at the Earth’s surface by physical, chemical, and biological processes.

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20
Q

Freeze-Thaw

A

Water expands as it freezes, causing cracks and fissures in rocks. Repeated freezing and thawing can break rocks apart.

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21
Q

Heating/Cooling

A

Repeated cycles of heating and cooling can cause rocks to expand and contract, weakening them and making them more susceptible to further weathering.

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22
Q

Salt Crystal Growth

A

Dissolving salts can crystallize within rock cracks, exerting pressure and causing the rock to crumble. This is common in arid environments.

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23
Q

Pressure Release (Dilatation)

A

As rocks are eroded and exposed to the surface, the pressure they were under is released. This pressure release can cause them to expand and crack.

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24
Q

Vegetation Root Action

A

Growing plant roots can exert pressure on rocks, wedging them apart and breaking them into smaller pieces.

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25
Q

Hydrolysis

A

Water reacts with minerals in rocks, breaking down their chemical structure and forming new compounds.

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26
Q

Hydration

A

Minerals absorb water molecules, expanding and weakening the rock structure.

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27
Q

Carbonation

A

Rainwater containing dissolved carbon dioxide becomes carbonic acid, which dissolves minerals like calcite (calcium carbonate) in limestone and creates new soluble compounds.

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28
Q

Climate’s affect on weathering

A

Temperature and precipitation play a major role. Warmer and wetter climates generally experience faster weathering rates.

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29
Q

Rock Type’s affect on weathering

A

Different rock types have varying susceptibility to weathering. For instance, porous rocks weather more easily than non-porous ones.

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30
Q

Rock Structure’s affect on weathering

A

Joints, cracks, and faults in rocks provide more surface area for weathering processes to attack.

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31
Q

Vegetation’s affect on weathering

A

Vegetation cover can protect rocks from physical weathering but can also promote chemical weathering through the production of organic acids.

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32
Q

Relief’s affect on weathering

A

Steeper slopes experience faster weathering due to increased exposure to water, wind, and gravity.

33
Q

Peltier Diagram

A

A graphical representation showing the relationship between temperature and precipitation, and their influence on the dominant weathering processes.

34
Q

High Temperatures and Low Rainfall Weathering Type

A

Chemical weathering dominates in hot, dry climates, with processes like carbonation being most effective.

35
Q

Low Temperatures and High Rainfall Weathering Type

A

Physical weathering dominates in cold, wet climates, with processes like freeze-thaw being most effective.

36
Q

Intermediate Temperatures and Rainfall Weathering Type

A

Both physical and chemical weathering processes can occur at moderate temperatures and precipitation levels.

37
Q

Slope Processes

A

The natural movements of rock, soil, and other debris down a slope due to gravity.

38
Q

Mass Movement

A

The downslope movement of a large mass of soil or rock under the influence of gravity.

39
Q

Heaves

A

Upward or outward movement of the ground surface, often caused by swelling clays or frost action.

40
Q

Flows

A

Rapid downslope movement of a saturated mass of soil or rock, like mudflows or debris flows.

41
Q

Slides

A

Downward movement of a relatively coherent mass of soil or rock along a defined surface. Types include rotational slides (circular) and translational slides (planar).

42
Q

Falls

A

Freefall of rock or debris from a steep slope or cliff, with minimal downslope movement.

43
Q

Steep Slope’s affect on mass movement

A

Steeper slopes are more susceptible to mass movement due to increased gravitational pull.

44
Q

Heavy Rainfall’s affect on mass movement

A

Water saturation weakens soil cohesion and increases weight, promoting instability.

45
Q

Loss of Vegetation’s affect on mass movement

A

Vegetation helps bind soil particles together and reduces surface water runoff. Loss of vegetation increases the risk of mass movement.

46
Q

Presence of Weak Layers’s affect on mass movement

A

Layers of loose material within the slope can act as slip surfaces for slides.

47
Q

Seismic Activity’s affect on mass movement

A

Earthquakes can trigger mass movement by shaking slopes and disturbing their stability.

48
Q

Loss of Life and Property as a result of mass movement

A

Large-scale mass movements can cause significant damage to infrastructure and endanger lives.

49
Q

Landscape Modification as a result of mass movement

A

Mass movement reshapes slopes, creating features like landslides scars, debris deposits, and new landforms.

50
Q

Rainsplash

A

Detachment and upslope movement of soil particles due to the impact of raindrops.

51
Q

Surface Runoff

A

Flow of water downslope across the surface after rainfall

52
Q

Sheetwash

A

Thin, widespread flow of water washing away a thin layer of soil.

53
Q

Rills

A

Concentrated flow of water in small channels, eroding narrow grooves into the slope.

54
Q

Soil Erosion

A

Removal of soil particles by water runoff, leading to land degradation and reduced fertility.

55
Q

Gully Development

A

Rills can deepen and widen into gullies, creating deep channels on slopes.

56
Q

Human Impact on Slope Stability

A

Human activities can both increase and decrease the stability of slopes.

57
Q

Deforestation

A

Removal of vegetation reduces root structures that bind soil particles and increases surface runoff, leading to erosion and slope instability.

58
Q

Slope Modification

A

Construction activities like road building, quarrying, and creation of steep building sites can alter slope angles and remove support structures, increasing the risk of mass movement.

59
Q

Overloading

A

Placing heavy structures or overloading slopes with waste materials can exceed their carrying capacity and trigger instability.

60
Q

Irrigation Practices

A

Excessive irrigation or leaky pipes can saturate slopes, weakening soil cohesion and increasing the risk of landslides.

61
Q

Pinning

A

Insertion of metal rods or pins into the slope to reinforce weak zones and prevent movement.

62
Q

Netting

A

High-strength netting applied to the slope face to trap falling debris and prevent further erosion.

63
Q

Grading

A

Reshaping the slope to a gentler angle to reduce the gravitational pull acting on the material.

64
Q

Afforestation

A

Planting trees and vegetation on bare slopes to bind soil particles, reduce surface runoff, and improve slope stability.

65
Q

Prevention

A

Identifying areas at risk and implementing preventative measures is more effective and less costly than dealing with landslides after they occur.

66
Q

Land-Use Planning

A

Avoiding development on steep slopes or areas prone to landslides.

67
Q

Drainage Control

A

Diverting surface water runoff away from slopes through ditches, channels, or proper drainage systems.

68
Q

Retaining Walls

A

Constructing walls to support slopes and prevent them from collapsing.

69
Q

Early Warning Systems

A

Installing monitoring systems to detect early signs of instability and allow for evacuation if necessary.

70
Q

Cause of Decreased Slope Stability in The Alps

A

Human activities in the Alps have contributed to a decline in slope stability.

71
Q

Effect of Ski Resort Development on The Alps

A

Extensive development of ski resorts has involved deforestation for ski runs and infrastructure construction. Reduced tree cover weakens the stabilizing effect of roots and increases surface runoff, leading to soil erosion and steeper slopes.

72
Q

Infrastructure Development

A

Building roads, railways, and other transportation networks often requires cutting into mountainsides, altering natural drainage patterns, and potentially creating unstable slopes.

73
Q

Impacts of Mass Movement on The Alps

A

Unstable slopes in the Alps pose a significant threat to life, property, and the natural environment.

74
Q

Loss of Life and Property in The Alps

A

Avalanches and landslides can destroy buildings, disrupt transportation networks, and cause fatalities.

75
Q

Disruption of Natural Processes in The Alps

A

Mass movements can alter river courses, damage natural ecosystems, and contribute to increased sediment loads in waterways.

76
Q

Strategies for Mitigating Risk in The Alps

A

A multi-pronged approach is needed to reduce the risk of mass movements in the Alps.

77
Q

Improved Land-Use Planning in the Alps

A

Identifying areas at risk for landslides and avalanches and restricting development in those zones can significantly reduce the risk of disasters. Several Alpine countries have implemented stricter regulations for construction in high-risk areas.

78
Q

Reforestation and Slope Stabilization in The Alps

A

Reforestation efforts and bioengineering techniques like planting shrubs and using natural materials to reinforce slopes can improve soil stability and prevent erosion. Austria, for instance, has projects underway to replant trees on slopes affected by ski resort development.

79
Q

Early Warning Systems in The Alps

A

Installing monitoring systems that track weather patterns, slope movement, and snow accumulation can provide early warnings of potential avalanches and landslides, allowing for evacuations. Many Alpine regions have implemented sophisticated early warning systems to monitor slope stability.