Weathering
DEFINITIONS
WEATHERING Brainstorm:
1) What is it?
2) What can cause it?
3) How does
weathering change
the surface of the
Earth?
Possible Causes:
WEATHERING
• Weathering= the breaking down of rock into
smaller and smaller pieces.
Is weathering constructive, destructive, or both?
Why?
-Weathering is destructive- it “tears down”
rocks and landforms.
2 Types of Weathering
Brainstorm
1) What
can
cause
each
type of
weatheri
ng?
WEATHERING
1) Mechanical 2) Chemical
Breaking down
rocks by physical
means
Chemical breakdown
of rock and minerals
into new substances
Possible causes:
Possible causes:
MECHANICAL WEATHERING
1. ANIMALS
Little animals also
help weathering
by burrowing and
digging through
the ground.
MECHANICAL WEATHERING
2. Ice Wedging –
when water gets into
cracks of a rock,
freezes & thaws over
& over again & splits
the rock
MECHANICAL WEATHERING
Ice
MECHANICAL WEATHERING
3. PLANT GROWTH
• Roots of plants also push
into the rocks and break
them apart. They act like
wedges and push the
rocks apart.
MECHANICAL WEATHERING
4. RELEASE OF PRESSURE- as erosion
moves sediment from the surface,
pressure is reduced. The outside of the
rock begins to flake off
MECHANICAL WEATHERING
NONLIVING CAUSES
5. Abrasion-
sediments carried by
wind, water, or ice wear
away rock by hitting &
scraping against other
rock
Abrasion
Wind
• sandstone shapes
eroded by coastal
winds
Sandblasting
Abrasion
WATER - rubs fragments against
each other and wears away the
surface of the rock by abrasion.
–
The faster the water, the greater
the erosion
Abrasion
• Ice- Glaciers
–The glacier
gouges out chunks
of rock and leaves
scratches on the
rock called
striations
CHEMICAL WEATHERING
• CHEMICAL WEATHERING
the chemical breakdown of rock
and minerals into new substances
CHEMICAL WEATHERING
Water is considered
to be the universal
solvent. It dissolves
many things – including
rock
• Over time, water can
break down even hard
rock like granite
CHEMICAL WEATHERING
2) Oxygen
Oxidation (rust)
is a chemical reaction
in which an iron
combines with oxygen.
CHEMICAL WEATHERING
3) Carbon Dioxide (CO2)
-CO2
mixing with water
creates Carbonic Acid that
slowly dissolves limestone.
(Acid in groundwater)
-Caves
CHEMICAL WEATHERING
4) Living Organisms
Acids from decaying plants or fungi such as
lichens breaks down rocks
CHEMICAL WEATHERING
5. ACID PRECIPITATION
is rain or snow that
contains more acids
than normal due to air
pollution.
The acid “dissolves”
and “eats away” the
rock
WEATHERING
How does
weathering
change the
surface of
the Earth?
Mechanical Weathering
Living Plant
Animal
Nonliving
Roots of plants also push into the
rocks and break them apart
burrowing and digging through the
ground
-water gets into cracks of a rock, freezes
Ice
(glacie & thaws over & over again & splits the rock
rs)
-scratches on the rock called striations
Wind
wears away the surface of the rock by
abrasion
Water
rubs fragments against each other and
wears away the surface of the rock by
abrasion.
Chemical Weathering
Living Plants
Acids from decaying plants or fungi
such as lichens breaks down rocks
Nonliving
Water
universal solvent. It dissolves many
things – including rock
Acid rain
rain or snow that contains more acids
than normal due to air pollution.
-acid “dissolves” or “eats away” the rock
CO2 mixing with water creates Carbonic
acid that slowly dissolves limestone
Groundwater
Oxidation chemical reaction in which an element
combines with oxygen to form an oxide
FORCES THAT CAUSE
Weathering
1) Mechanical
Living
Plants
Nonliving
Ice -
(Glaciers)
2) Chemical
Living
Plants
Nonliving
Water
Wind
Acid rain
Groundwater
Water
Oxidation
Animals
Interactive Weathering
• How are materials from the earth broken
down?