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Questions and Answers
What is the primary driving force behind mass wasting?
What is the primary driving force behind mass wasting?
Mechanical weathering results in chemical changes within rocks.
Mechanical weathering results in chemical changes within rocks.
False
Name one process involved in chemical weathering.
Name one process involved in chemical weathering.
Oxidation
The process where water enters rock spaces, freezes, and expands is known as __________.
The process where water enters rock spaces, freezes, and expands is known as __________.
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Match the type of erosion to its description:
Match the type of erosion to its description:
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Which of the following processes is NOT a type of mechanical weathering?
Which of the following processes is NOT a type of mechanical weathering?
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Biological activity can contribute to both physical and chemical weathering.
Biological activity can contribute to both physical and chemical weathering.
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What is the term for the process where the outer layer of rocks peels off due to temperature changes?
What is the term for the process where the outer layer of rocks peels off due to temperature changes?
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Which method involves the transport of particles by air, water, or ice?
Which method involves the transport of particles by air, water, or ice?
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Deltas are formed when a river gains energy as it flows into fast-moving water.
Deltas are formed when a river gains energy as it flows into fast-moving water.
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What is the term for the deposit of a stream?
What is the term for the deposit of a stream?
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Glacial till consists of __________ deposits left by glaciers.
Glacial till consists of __________ deposits left by glaciers.
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Match the following landforms with their descriptions:
Match the following landforms with their descriptions:
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What type of erosion involves the continuous flow of water eroding valleys deeper?
What type of erosion involves the continuous flow of water eroding valleys deeper?
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Debris flows are caused by heavy rains and can move at velocities ranging from 1 m/yr to 100 m/h.
Debris flows are caused by heavy rains and can move at velocities ranging from 1 m/yr to 100 m/h.
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What is the primary agent of erosion?
What is the primary agent of erosion?
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In __________ erosion, narrow channels are formed and eroded into depth by heavy rains.
In __________ erosion, narrow channels are formed and eroded into depth by heavy rains.
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Which type of mass wasting involves slow movement, often seen in bent trees and fences?
Which type of mass wasting involves slow movement, often seen in bent trees and fences?
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Match the erosion types with their descriptions:
Match the erosion types with their descriptions:
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Wind erosion is primarily responsible for the formation of glaciers.
Wind erosion is primarily responsible for the formation of glaciers.
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What are the two types of landslides?
What are the two types of landslides?
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Study Notes
Exogenic Processes
- Processes that occur at or near the Earth's surface and cause the surface to wear away.
- Classified into two main categories: degradation and aggradation.
Degradation
- Refers to the breaking down of landforms.
- Includes weathering, mass wasting, transportation, and erosion.
Weathering
- The process of breaking down rocks, soil, and minerals through physical or chemical means.
- Two types: mechanical and chemical weathering.
Mechanical Weathering
- Physical disintegration of rocks into smaller fragments without altering their mineral composition.
- Examples:
- Frost wedging: Water enters rock cracks, expands when frozen, and breaks the rock apart.
- Thermal stress: Temperature changes cause rocks to expand and contract, leading to fracturing.
- Pressure release: Overlying rocks erode, reducing pressure on underlying rocks, causing them to expand and fracture.
- Organic activity: Human activities like mining, road construction, and even walking can contribute to weathering.
Chemical Weathering
- Decomposition of rocks through chemical reactions that alter their mineral composition.
- Examples:
- Oxidation: Oxygen reacts with minerals, forming oxides like rust, weakening the rocks.
- Hydrolysis: Water reacts with minerals, dissolving them and creating new minerals.
- Carbonation: Carbon dioxide in rainwater forms carbonic acid, which dissolves calcium carbonate in rocks.
- Biological action: Organic acids from decaying plant matter can dissolve minerals in rocks.
Mass Wasting
- Movement of rock, soil, and regolith downhill due to gravity.
- Types:
- Rock and debris fall: Sudden, rapid movements of rock fragments or debris down steep slopes.
- Landslides: Rapid movements of soil, rock, or regolith along a slope.
- Translational slides: Movement along a well-defined surface.
- Rotational slides (slumps): Movement along a concave upward surface.
- Flows: Movement of material behaving like a liquid.
- Slurry flows: Material with 20-40% water content.
- Solifluction: Very slow movement in water-saturated areas.
- Debris flows: Rapid movements triggered by heavy rainfall.
- Mudflows: High-velocity flows of sediment and water, often caused by heavy rains.
- Granular flows: Material with 0-20% water content.
- Creep: Extremely slow movement, often evident in bent trees and fences.
- Earthflows: Moderate velocities of sediment and water.
- Debris avalanches: Rapid, destructive flows of large rock and regolith.
- Slurry flows: Material with 20-40% water content.
Erosion
- The process of transporting materials from one location to another by wind, water, or ice.
- Agents:
- Water: Most significant agent, responsible for splash, sheet, gully, valley, bank, and coastline erosion.
- Wind: Transports dust, sand, and ash, eroding landforms and creating features like sand dunes and ventifacts.
- Ice: Glaciers erode land through plucking (removing rock fragments) and abrasion (scraping bedrock with debris).
Types of Water Erosion
- Splash erosion: Raindrops detach and move soil particles.
- Sheet erosion: Water flows downslope, eroding soil in a thin sheet.
- Gully erosion: Heavy rains carve deep channels in the land.
- Valley erosion: Continuous water flow deepens valleys over time.
- Bank erosion: Streams and rivers erode their banks, widening channels.
- Coastline erosion: Ocean waves erode rocks and cliffs, shaping coastlines.
- Seaside cliff erosion: Waves erode cliffs, forming caves, arches, and sea stacks.
Wind Erosion
- Wind transports dust, sand, and ash, eroding landforms and creating features.
- Polishes rocks and cliffs.
- Creates sand dunes and ventifacts (rocks shaped by wind abrasion).
Ice Erosion
- Glaciers shape the landscape through plucking and abrasion.
- Plucking: Glaciers pick up and transport rock fragments from bedrock.
- Abrasion: Glaciers grind and scratch bedrock with embedded debris.
Transportation of Materials
- Eroded materials are transported in various ways:
- Solution: Dissolved minerals in water.
- Suspension: Fine particles carried by air, water, or ice.
- Traction: Rolling, sliding, and shuffling of particles along surfaces.
- Saltation: Particles bounce along the surface in repeated cycles.
Deposition
- The process of eroded materials settling in a new location.
- Occurs when the transporting agent loses energy.
Water and Landforms
- Water deposition creates features such as:
- Deltas: Formed when rivers enter a slow-moving body of water, losing energy and depositing sediment.
- Alluvial fans: Formed when streams reach a flat area and deposit sediment.
- Floodplains: Wide areas of alluvium formed by repeated flooding.
- Levees: Natural embankments along river channels formed by deposition during floods.
Glaciers and Landforms
- Glacial deposition creates features such as:
- Glacial till: Unsorted sediment deposited by melting glaciers.
- Moraines: Ridges of glacial till formed at the edges of glaciers.
- Eskers: Winding ridges formed by sediment deposited by glacial streams.
- Drumlins: Streamlined hills formed by glacial erosion and deposition.
- Kames: Steep-sided hills formed by deposition of sediment in glacial depressions.
Wind and Landforms
- Wind deposition creates features such as:
- Loess: Wind-deposited silt, forming broad layers.
- Sand dunes: Hills of sand formed by wind action in deserts and coastal areas.
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