3. Rocks and Weathering

Question 1

Plate Tectonics

Answer 1

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

Question 2

Size and Composition of Plates

Answer 2

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

Question 3

Movement of Plates

Answer 3

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

Question 4

Global Patterns of Plate Movement

Answer 4

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

Question 5

Divergent (Constructive) Boundaries

Answer 5

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

Question 6

Key Features of Constructive Plate Boundaries

Answer 6

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

Question 7

Conservative Boundaries

Answer 7

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

Question 8

Key Features of Conservative Plate Boundaries

Answer 8

Transform faults and mountain ranges.

Question 9

Convergent (Destructive) Boundaries

Answer 9

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

Question 10

Subduction Zone Characteristics

Answer 10

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

Question 11

Seafloor Spreading

Answer 11

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

Question 12

Subduction

Answer 12

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

Question 13

Landforms of Subduction

Answer 13

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

Question 14

Fold Mountain Building

Answer 14

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

Question 15

Examples of Fold Mountains

Answer 15

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

Question 16

Ocean Ridges

Answer 16

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

Question 17

Ocean Trenches

Answer 17

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

Question 18

Volcanic Island Arcs

Answer 18

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

Question 19

Weathering

Answer 19

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

Question 20

Freeze-Thaw

Answer 20

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

Question 21

Heating/Cooling

Answer 21

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

Question 22

Salt Crystal Growth

Answer 22

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

Question 23

Pressure Release (Dilatation)

Answer 23

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.

Question 24

Vegetation Root Action

Answer 24

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

Question 25

Hydrolysis

Answer 25

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

Question 26

Hydration

Answer 26

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

Question 27

Carbonation

Answer 27

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

Question 28

Climate’s affect on weathering

Answer 28

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

Question 29

Rock Type’s affect on weathering

Answer 29

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

Question 30

Rock Structure’s affect on weathering

Answer 30

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

Question 31

Vegetation’s affect on weathering

Answer 31

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

Question 32

Relief’s affect on weathering

Answer 32

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

Question 33

Peltier Diagram

Answer 33

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

Question 34

High Temperatures and Low Rainfall Weathering Type

Answer 34

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

Question 35

Low Temperatures and High Rainfall Weathering Type

Answer 35

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

Question 36

Intermediate Temperatures and Rainfall Weathering Type

Answer 36

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

Question 37

Slope Processes

Answer 37

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

Question 38

Mass Movement

Answer 38

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

Question 39

Heaves

Answer 39

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

Question 40

Flows

Answer 40

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

Question 41

Slides

Answer 41

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

Question 42

Falls

Answer 42

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

Question 43

Steep Slope’s affect on mass movement

Answer 43

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

Question 44

Heavy Rainfall’s affect on mass movement

Answer 44

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

Question 45

Loss of Vegetation’s affect on mass movement

Answer 45

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

Question 46

Presence of Weak Layers’s affect on mass movement

Answer 46

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

Question 47

Seismic Activity’s affect on mass movement

Answer 47

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

Question 48

Loss of Life and Property as a result of mass movement

Answer 48

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

Question 49

Landscape Modification as a result of mass movement

Answer 49

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

Question 50

Rainsplash

Answer 50

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

Question 51

Surface Runoff

Answer 51

Flow of water downslope across the surface after rainfall

Question 52

Sheetwash

Answer 52

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

Question 53

Rills

Answer 53

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

Question 54

Soil Erosion

Answer 54

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

Question 55

Gully Development

Answer 55

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

Question 56

Human Impact on Slope Stability

Answer 56

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

Question 57

Deforestation

Answer 57

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

Question 58

Slope Modification

Answer 58

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.

Question 59

Overloading

Answer 59

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

Question 60

Irrigation Practices

Answer 60

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

Question 61

Pinning

Answer 61

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

Question 62

Netting

Answer 62

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

Question 63

Grading

Answer 63

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

Question 64

Afforestation

Answer 64

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

Question 65

Prevention

Answer 65

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

Question 66

Land-Use Planning

Answer 66

Avoiding development on steep slopes or areas prone to landslides.

Question 67

Drainage Control

Answer 67

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

Question 68

Retaining Walls

Answer 68

Constructing walls to support slopes and prevent them from collapsing.

Question 69

Early Warning Systems

Answer 69

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

Question 70

Cause of Decreased Slope Stability in The Alps

Answer 70

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

Question 71

Effect of Ski Resort Development on The Alps

Answer 71

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.

Question 72

Infrastructure Development

Answer 72

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

Question 73

Impacts of Mass Movement on The Alps

Answer 73

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

Question 74

Loss of Life and Property in The Alps

Answer 74

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

Question 75

Disruption of Natural Processes in The Alps

Answer 75

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

Question 76

Strategies for Mitigating Risk in The Alps

Answer 76

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

Question 77

Improved Land-Use Planning in the Alps

Answer 77

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.

Question 78

Reforestation and Slope Stabilization in The Alps

Answer 78

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.

Question 79

Early Warning Systems in The Alps

Answer 79

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.