74 Questions
What type of weathering is the focus of this lesson?
Mechanical weathering
Which process makes rocks expand and contract due to temperature changes?
Thermal expansion
What causes frost weathering (ice wedging) to occur?
Water freezing and expanding in rock cracks
Which type of weathering involves the peeling and breaking away of the outer layer of rock?
Exfoliation
What type of weathering is caused by living organisms like plants and microorganisms?
Biological weathering
Which of the following is NOT a form of chemical weathering mentioned in the text?
Hydration
Which farming practice involves keeping stalks in the ground over the winter to hold soil in place?
No-till farming
What is the term for the practice of growing different crops on the same plot of land in sequential seasons to help soil quality and control erosion?
Crop rotation
What type of material is primarily involved in debris flow mass-wasting process?
Mud
Which mass-wasting process involves slow downslope movement and can even happen synchronously with tree growth, causing bending on tree trunks?
Creep
What is the main factor that can help decrease mass wasting and protect human lives and structures?
Afforestation
What is the resistive force that holds land together through a combination of gravity and friction, preventing mass-wasting events?
Shear strength
What plays a significant role in enhancing chemical weathering processes?
Water and oxygen
Why do rocks fully exposed to the atmosphere weather more rapidly?
Exposure to environmental elements like wind and temperature fluctuations
Which type of climate tends to experience higher rates of weathering?
Warm, humid climates
What does soil erosion result from?
Wind, water, or gravity moving soil
Which type of soil structure is preferred for growing fruits and vegetables?
Granular soil structure
Why does heavily tilled soil erode more easily than soil planted with vegetation?
More likely to be eroded by wind or water
What factor can trigger mass wasting by decreasing the shear force within a slope?
Earthquakes
Which type of mass wasting is referred to as a rotational slide due to its sliding motion?
Slump
What type of stress is compressional stress similar to?
Shear stress
Which type of rock deformation is not reversible and leads to rock breaking?
Fracture
What type of linear fold has arches with older rocks at the center?
Anticlines
What geological feature is formed by the application of compressive stress to layers of rock?
Folds
What type of fault occurs at a convergent boundary?
Reverse fault
Which type of mountain is formed when magma pushes towards the Earth's surface but cools prior to being extruded?
Dome mountains
What is the main component involved in the formation of fold mountains?
Tectonic plate collision
Which type of stress causes a reverse fault to form?
Compressional stress
What causes the formation of hotspot mountains like those in Hawai'i?
Magma emergence
Which process in the water cycle involves water changing phases from gas to liquid?
Condensation
What is the primary mechanism by which precipitation returns water to the surface?
Runoff
Which phase change process involves water changing from a liquid to a gas?
Evaporation
Where does transpiration occur in plants?
Leaves
Which statement accurately describes the distribution of water on Earth?
Less than 1% of the world's water is freshwater.
What percentage of all freshwater is found underground according to the text?
30%
Which phase in the water cycle involves water returning to the Earth's surface?
Precipitation
Which phase of the water cycle involves water moving from Earth's surface to the atmosphere?
Transpiration
What is the main focus of mechanical weathering?
Breaking down rocks by physical means into smaller pieces
Which of the following processes involves water freezing and expanding in the cracks of rocks to cause weathering?
Frost weathering (ice wedging)
What type of weathering involves minerals left behind after water evaporation that push into cracks in rocks?
Salt Crystal Growth
Which living organisms contribute to biological weathering according to the text?
Plants, animals, fungi, and microorganisms
What is the result of the outer layer of rock peeling and breaking away as pressure above it lessens?
Exfoliation
Which type of weathering can weaken rocks by hitting, scraping, and chipping away against each other?
Abrasion
What factor affects the rate of weathering by causing rocks fully exposed to the atmosphere to weather more rapidly?
Exposure to environmental elements
Which mineral present in rocks contributes to rapid weathering when mixed with water, oxygen, and other elements?
Iron
What characteristic of climates like the tropics leads to higher rates of weathering compared to cold, dry climates?
Higher humidity
Which type of soil structure is most suitable for growing fruits and vegetables?
Granular
What is the purpose of planting shelterbelts as a best practice to prevent soil erosion?
To guard soil against wind erosion
What process can result in soil quality reduction due to the loss of the most nutrient-rich layer?
Erosion
Which type of mass wasting involves the downslope movement of broken fragments of various sizes of rocks and soil?
Earthflow
Which geological agent significantly enhances chemical weathering processes by creating acids?
Microbial organisms
How is no-till farming beneficial in preventing soil erosion?
By holding soil in place over winter
What is the primary characteristic of mudflows as a mass-wasting process?
Associated with volcanic eruptions
How does crop rotation help control erosion of fields?
By improving soil quality
What role does shear strength play in preventing mass-wasting events?
It holds land together through a combination of gravity and friction
Which geological feature is formed by the application of compressive stress to layers of rock?
Anticline
What type of mass-wasting event involves the sliding of coherent rock material along a curved surface?
Slump
What type of rock deformation is reversible and does not lead to rock breaking?
Elastic deformation
Why does a rockslide differ from a slump in its movement pattern?
Rockslides move as translational slides, slumps move rotationally.
Which type of stress causes rock to slip horizontally?
Shear stress
What is the primary factor determining whether a rock will flow or break under stress?
Material composition
What phase change process involves water changing from a gas to a liquid?
Condensation
Where is most of the freshwater on Earth found?
Glaciers and ice caps
What is the main mechanism through which water returns to the groundwater supply?
Infiltration
Which phase of the water cycle involves water moving from the Earth's surface to the atmosphere?
Evaporation
What percentage of all water on Earth is freshwater?
3%
Which factor influences increased rates of evapotranspiration?
Strong winds
What contributes to enhancing chemical weathering processes?
Presence of organic matter
What is the primary classification used to identify each fold?
Tightness of the folds, axial plane orientation, and bed thickness
How are domes and basins formed?
When two anticlines or synclines connect
What is the hanging wall in a fault?
The block of rock that sits above the fault
What type of fault forms along divergent boundaries?
Normal fault
Which type of mountain is created at the boundary of two continental tectonic plates that collide?
Fold mountains
How do Hawaii's hotspot mountains differ from other types of mountains according to the text?
They occur away from tectonic continental plate boundaries
Study Notes
Soil Conservation and Erosion
- The USDA offers incentives to farmers to use best practices to prevent soil erosion.
- Best practices include:
- Planting shelterbelts
- Preventing overgrazing
- No-till farming
- Planting cover crops
- Using mulch or soil matting
- Strip cropping
- Terracing
- Contour farming
- Crop rotation
- Soil erosion can be controlled by:
- Preventing overgrazing
- Planting shelterbelts
- Implementing no-till farming
- Using terracing and contour farming on sloped land
- Practicing crop rotation to maintain soil quality
Mass Wasting
- Mass wasting is the downslope movement of rock, soil, and debris due to gravity.
- Types of mass wasting include:
- Slumps: slow, curved motion of semi-consolidated material
- Rockslides: rapid, destructive motion of rock and debris
- Debris flow: rapid motion of broken rock and soil fragments
- Earthflow: slow motion of fine-grained material
- Creep: slow, imperceptible movement of soil and rock
- Mass wasting can be triggered by:
- Increased precipitation
- Loss of vegetation
- Earthquakes
- Steep slopes
- Effects of mass wasting:
- Harm to human and animal life
- Damage to infrastructure and property
- Economic losses
Weathering
- Weathering is the breakdown of rocks into smaller particles.
- Types of weathering:
- Mechanical weathering: physical breakdown of rocks
- Chemical weathering: chemical breakdown of rocks
- Examples of mechanical weathering:
- Thermal expansion
- Frost wedging
- Exfoliation
- Abrasion
- Salt crystal growth
- Biological weathering: breakdown of rocks by living organisms
Soil Composition and Development
- Soil is a mixture of sediment, minerals, organic matter, gases, liquids, and organisms.
- Soil composition can vary in:
- Particle size (sand, silt, clay, loam)
- Structure (granular, platy, columnar)
- Soil development:
- Weathering and erosion of rocks
- Deposition of sediment
- Formation of soil horizons
- Contributions from pioneer species
Soil Erosion
- Soil erosion is the removal of soil from one location to another through wind, water, or gravity.
- Factors affecting soil erosion:
- Exposure to wind and water
- Lack of vegetation
- Slope steepness
- Effects of soil erosion:
- Reduced soil quality
- Decreased crop yields
- Water pollution
- Loss of nutrients and fertilizers### Weathering
- Weathering is the process of breaking down rocks on the Earth's surface into smaller pieces.
- There are two main types of weathering: mechanical and chemical weathering.
- Mechanical weathering involves physical forces that break down rocks, such as:
- Thermal expansion: temperature changes causing rocks to expand and contract.
- Frost weathering (ice wedging): water freezing and expanding in cracks, making them bigger.
- Exfoliation: outer layer of rock peeling and breaking away as pressure above it lessens.
- Abrasion: rocks carried by wind, ice, water, or gravity hitting and scraping against each other.
- Salt crystal growth: minerals left behind after evaporation leaving behind crystals that push into and through cracks.
Chemical Weathering
- Chemical weathering involves chemical reactions that break down rocks.
- Forms of chemical weathering include:
- Acidification
- Carbonation
- Hydrolysis
- Oxidation
- Living organisms
Folds
- Folds are geological features caused by compressive stress on layers of rock.
- Three main types of folds:
- Anticlines: arches with older rocks at the center.
- Synclines: concave up with older rocks on the outside.
- Monoclines: one prominent dipping limb.
Tectonic Plates
- The Earth's crust is made up of seven different tectonic plates.
- A plate boundary is where two tectonic plates meet.
- Faults are fractures in the rocks along a plate boundary.
- Types of faults:
- Normal fault: hanging wall moves downward below the footwall.
- Reverse fault: hanging wall moves upward above the footwall.
- Strike-slip fault: blocks of rock slide past each other.
Orogeny
- Orogeny is the process of mountain formation.
- Mountains can be formed in several ways:
- Fold mountains: formed at the boundary of two continental tectonic plates.
- Dome mountains: formed when magma pushes towards the Earth's surface.
- Hot spot mountains: formed when magma emerges from the crust and land passes over the eruption.
- Subduction: when one plate sinks below another.
Water Cycle
- The water cycle is the process of recycling freshwater on Earth.
- Three main parts of the water cycle:
- Evaporation
- Condensation
- Precipitation
- Other processes involved in the water cycle:
- Sublimation
- Transpiration
- Runoff
- Infiltration
Soil
- Soil is a medium that consists of a mixture of sediment, minerals, organic matter, gases, liquids, and organisms.
- Soil takes a long time to accumulate and develop.
- Soil composition:
- Weathered sediments (sand, silt, clay, loam)
- Organic matter
- Soil structures (granular, platy, columnar)
- Soil profile:
- Topsoil
- Soil horizons
- Bedrock
Soil Erosion
- Soil erosion is the result of wind, water, or gravity moving soil from one place to another.
- Factors that contribute to soil erosion:
- Exposure of soil
- Wind and water
- Poor soil quality
- Lack of vegetation
- Methods to prevent soil erosion:
- Planting shelterbelts
- No-till farming
- Planting cover crops
- Using mulch or soil matting
- Strip cropping
- Terracing
- Contour farming
- Crop rotation
Mass Wasting
- Mass wasting is the movement of rock, soil, and debris down a slope due to gravity.
- Types of mass wasting:
- Slumps
- Rockslides
- Debris flows
- Earthflows
- Creep
- Causes of mass wasting:
- Increased slope steepness
- Too much water
- Decreased vegetation
- Disruptive events (earthquakes)
- Effects of mass wasting:
- Harm to human and animal life
- Damage to infrastructure
- Economic impacts
Stresses and Deformation
- Rocks experience stress and deformation due to external forces.
- Types of stress:
- Tensional stress
- Compressional stress
- Shear stress
- Phases of deformation:
- Elastic deformation
- Ductile deformation
- Fracture
- Factors that influence rock deformation:
- Material properties
- Temperature
- Water
Learn about mechanical weathering, a process that breaks down rocks on the Earth's surface through physical means. Explore different examples, including thermal expansion and frost weathering (ice wedging), that weaken rocks.
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