Transcript Weathering and Erosion

Weathering and Erosion
Weathering
• The breakdown do the materials of
Earth’s crust into smaller pieces.
Physical Weathering
• Process by which rocks are broken down
into smaller pieces by external conditions.
• Types of Physical weathering
– Frost heaving and Frost wedging
– Plant roots
– Friction and impact
– Burrowing of animals
– Temperature changes
Frost Wedging
Frost Heaving
Plant Roots
Plants CAN PREVENT erosion
Friction and Repeated Impact
Burrowing of Animals
Temperature Changes
Chemical Weathering
• The process that breaks down rock
through chemical changes.
• The agents of chemical weathering
– Water
– Oxygen
– Carbon dioxide
– Living organisms
– Acid rain
Water
• Water weathers rock by dissolving it
Oxygen
• Iron combines with
oxygen in the
presence of water in
a processes called
oxidation
• The product of
oxidation is rust
Carbon Dioxide
• CO2 dissolves in rain water and creates
carbonic acid
• Carbonic acid easily weathers limestone
and marble
Living Organisms
• Lichens that grow on rocks produce weak
acids that chemically weather rock
Acid Rain
• Compounds from burning coal, oil and gas
react chemically with water forming acids.
• Acid rain causes very rapid chemical
weathering
Erosion
• The process by which water, ice, wind or
gravity moves fragments of rock and soil.
Water Erosion
• Rivers, streams, and runoff
Water causes weathering
What evidence of
weathering do you see
in this picture?
Ice Erosion
• Glaciers
Ice Causes Erosion
Glaciers can pick up and carry sediment that ranges in size
from sand grains to boulders bigger than houses.
Moving like a conveyor belt and a bulldozer, a single
glacier can move millions of tons of material!
Wind Erosion
Wind causes weathering
Why wasn’t this mass
of land weathered
away?
What evidence of
weathering do you see
in this picture?
Mass Movements
• Landslides, mudslides, slump and creep
landslide clip.mpeg
Gravity causes erosion
Creep, Slump, Landslides, Mudslides, and Avalanches.
Slower
Faster
These are examples of mass movement
landslide clip.mpeg
(or called mass wasting)
Deposition
Rock particles that are picked up and transported
during erosion will ultimately be deposited
somewhere else
Deposition is the process by which sediments (small
particles of rock) are laid down in new locations.
• Together, Erosion and Deposition build new
landforms.
Delta
Where rivers meet the
ocean is called the
mouth of the river.
Soil and dirt carried
by these rivers is
deposited at the
mouth, and new land
is formed. The new,
soil-rich land is known
as a Delta