Download Weathering & Erosion

Weathering
Weathering is the process that
produces change in the surface
of rocks exposed to the
atmosphere and/or
hydrosphere.
Two Categories Of Weathering:

Mechanical
 Chemical weathering
weathering is the
is where the rock
breakdown of rock
material is changed
into smaller bits and
into another
pieces without a
substance by reacting
change in its chemical
with a chemical.
makeup.
ex: hitting, scratching,
cracking

Frost action (ice wedging)-
1. Water seeps into small
cracks in rocks.
2.When the water freezes it
expands creating great
pressure.
3. The crack widens and
allows water to seep
deeper into the rock.
 Plant action-
1. Tiny root hairs
seek out small
cracks and pits in
rock.
2.Once the root
hairs find a place
they grow and
expand.
3.The expansion
causes great
pressure and cracks
the rock.

Exfoliation
1.
2.
3.
Rocks formed deep
in the Earth are
made under high
pressure.
When the pressure
is released the rocks
expand & crack.
May also be caused
by alternate heating
and cooling of rocks
by weather
conditions.
Abrasion-
grinding away
of rock by
water, wind, ice,
or rubbing other
rocks.
 Wetting
and
Drying
When earth gets
wet it expands
As it dries it
cracks
OxidationOxygen in the
atmosphere
chemically
reacts with
minerals.
ex.: rusting of a
nail
 Water
(hydrolysis)
Minerals are
dissolved in
water.
ex.: Halite,
calcite
 Acid-
Carbonic acid:
C02 dissolves in
rain water
forming a weak
acid.
ex. stalactites
and stalagmites
Acid Rain:
Sulfur Dioxide in
the atmosphere
dissolves in rain
water forming a
strong acid
(sulfuric acid).
Time For a Investigation
 One
student has a bowl with a rock and
small croutons in it.
 Another student has a bowl with a rock
and a large crouton in it.
 Both students will aggressively shake
their bowls.
 Which crouton
will experience the
most weathering?
Rates of Weathering will depend
on:
Surface area exposed - weathering
occurs on the surface. More
surface exposed, the faster the
weathering will occur.
A full, solid block has
the least surface area.
The interior is safe
from exposure.
A smashed piece has
greatest
surface area exposed.
The interior can now be
attacked.
Rates of Weathering will depend on:
 Mineral composition- some
minerals
are more resistant than others.
–ex.:Quartz is resistant to
chemical and physical
weathering.
Rates of Weathering will depend on:
 Climatic Conditions:
Cold and/or dry climates favor
physical weathering.
Warm and wet climates favor chemical
weathering.
Frost action works best in areas where
the temperature fluctuates wildly.
LET’S SEE IF YOU CAN FIGURE THIS
OUT????
Where is the rock more resistant to
weathering?
Where is the rock least resistant to
weathering?
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