Transcript Weathering and Erosion

Weathering and Erosion
Weathering
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The breakdown of the materials of Earth’s crust
into smaller pieces called sediments - sand, silt,
and clay.
Weathering shapes the Earth’s surface.
Mechanical Weathering
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Process by which rocks are broken down
into smaller pieces by physical processes.
Types of Mechanical weathering
1.
2.
3.
4.
5.
Ice wedging
Plant roots
Burrowing of animals
Friction and impact
Temperature changes
1. Ice Wedging
Water freezing and
thawing in cracks of
rocks will break them
down over time.
2. Plant Roots
Plant roots
grow in the
cracks of
rocks, and
wedge
them
apart.
3. Burrowing of Animals
As animals burrow in the ground, they loosen
sediments and push them to the surface.
4. Friction and Repeated Impact
Sediments carried by wind
and water will weather
Earth’s crust into smaller
pieces and unusual shapes.
5. Temperature Changes
Changes in climate temperatures and
disasters like wild fires cause erosion.
Chemical Weathering
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Occurs when chemical reactions dissolve the
minerals in rocks, or change them into different
minerals.
The agents of chemical weathering
1.
2.
3.
4.
5.
Water
Oxygen
Carbon dioxide
Living organisms
Acid rain
1. Water
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Water weathers rock by dissolving it
2. Oxygen
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Iron combines with
oxygen in the
presence of water in
a processes called
oxidation
The product of
oxidation is rust
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3.
Carbon
Dioxide
dissolves in rain water and creates
CO2
carbonic acid
Carbonic acid easily weathers limestone
and marble, this can cause underground
caves
4. Living Organisms
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Lichens that grow on rocks produce weak
acids that chemically weather rock
5. Acid Rain
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Compounds from burning coal, oil and gas
react chemically with water forming acids.
Acid rain causes very rapid chemical
weathering
Erosion
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The process by which water, ice, wind or
gravity moves fragments of rock and soil.
Gravity: Mass Movements
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Landslides, mudslides, rockslides, slump and
creep all move downhill from the pull of gravity
Ice Erosion
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Glaciers: large mass of ice and snow that
change features of the Earth’s surface
Wind Erosion
Wind erodes the surface in 2
ways:
1. Deflation: wind blows loose
sediments; carrying tiny
particles and leaving heavier
materials behind
2. Abrasion: windblown
sediments strike rocks and
other surfaces which are worn
down over time
Water Erosion
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Rivers, streams, runoff, floods, ocean waves
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Deposition is the geological process by
which material is added to a landform or
land mass