Weathering and
Erosion
Amole
Spectra of Science
2013
Weathering vs. Erosion
• They work together,
but are NOT the
same thing
• Weathering is a
process that breaks
down rock
• Erosion is a process
that moves rock
Weathering is like the
hammer.
Erosion is like the
truck.
Types of Weathering
• Physical- breaks down rock without
changing its chemical composition
– Frost wedging
– Plant roots
– Wind
– Water
• Chemical-breaks down rock by
changing its chemical composition
– CO2
– Acid Precipitation
– Rust
Frost Wedging
•
•
•
•
Physical Weathering
Water seeps into cracks
Freezes and expands
Pushes rock apart
Root Pry
• Physical Weathering
• Plant roots grow into
rock
• Pushes rock apart
Wind Abrasion
• Physical Weathering
• Wind carrying sand blasts against these rocks
causing them to become rounded
Animal Burrows
• Physical Weathering
• Animals create tunnels in rock and sediments
breaking them up
Water Abrasion
• Physical Weathering
• Running water
repeatedly flows
over river rocks
making them smooth
Oxidation of Iron
• Chemical Weathering
• This rock is red
because of the
oxidation of iron in
the sediment when
the rock was being
formed
Acid Precipitation
1908
1969
• Chemical Weathering
• Released gases from
burning fossil fuels
react with water in
the air to create acids
• This acid reacts with
limestone to
decompose it
Living Organisms
• Lichens that grow on rocks produce weak
acids that chemically weather rock
Water
• Chemical Weathering
• Water can dissolve minerals found in rocks
Water
• Chemical Weathering
• Water can dissolve minerals found in rocks
Carbon Dioxide
• Chemical Weathering
• Reacts with water to
form acid
Erosion
• Process by which rock is moved or
transported
• Deposition- process by which material
(sediments) are laid down
Water Erosion
• Water transports and then eventually deposits
sediments
• Can create deltas, meanders, canyons, and
flood plains
Meander
• S-shaped streams
• Wander side to side seeking lowest elevation
Delta
• Occur where rivers
meet the ocean
• Soil, dirt, sediments
deposited at river
mouth
• Creates new soil-rich
land
Canyons
• Large valleys created
by rivers or streams
over time
• Grand Canyon “cut”
by Colorado River
Wind Erosion
• Wind picks up and carries sediments to new
locations
• Creates sand dunes
Erosion by Gravity
• Gravity causes large
masses off rocks and
sediments to move
from higher locations
to lower ones
• Ex: avalanches, land
slides, and mudslides
Erosion by Ice
• Glaciers carve U-shaped
valleys as they pick up
and carry rock
fragments along the
way
Weathering
and Erosion
QUIZ
Frost Wedging
Physical
Weathering
Chemical
weathering
Rust
Root Pry
Physical
Weathering
Water Erosion
Erosion by Glacier
Erosion by Gravity
Erosion by
Gravity
Physical Weathering- Frost Wedging
Erosion- Wind
Chemical Weathering- Acid Precipitation
The marble grave marker has been attacked by acidic
rain because of the calcite composition. The grave
marker on the right, while old, has not been
dissolved because of its granite composition
Physical
WeatheringTree Pry
Erosion by
Gravity