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Weathering
By: Katherine Pease
7th Grade Plummer Middle
http://www.geosci.unc.edu/faculty/glazner/Images/Weathering/weathering.html
School
What is Weathering?
Weathering
is
the breaking
down of rock
near the
surface of the
Earth.
A wooden post that soaked for many years in a pool of brine in Owens
Lake (dry), eastern California. The grotesque swelling of the wood results
from deposition of salts in the wood.
http://www.geosci.unc.edu/faculty/glazner/Images/Weathering/weathering.html
What are the two main types of
weathering?
Mechanical
Weathering
Chemical
Weathering
http://www.geography4kids.com/files/land_weathering.html
Mechanical
Weathering,
what is that?
It
is the
process of
breaking big
rocks into
little ones by
physical
means.
What causes this mechanical
weathering to happen?
Abrasion
Wedging
Water
Wind
Ice
Plants
Animals
What is Abrasion?
Abrasion
refers to the
breaking and
grinding
away of solid
rock by
collisions with
moving
particles.
What is Biotic Weathering?
A
form of
Mechanical
Weathering
that is caused
by living
organisms
How do plants and animals cause
mechanical / biotic weathering?
Roots
and plants push into
the rocks and break them
apart. They act like wedges
and push the rocks apart.
Little animals also help by
burrowing and digging
through the ground.
http://www.geography4kids.com/files/land_weathering.html
How does wind cause mechanical
weathering?
 Some
rocks that
are composed of
soft minerals or are
composed of
particles that are
not well cemented
may break down
when struck by
windblown sand or
smaller-sized
particles.
What is Frost Wedging?
 FROST
WEDGING.
There are already
some small cracks in
boulders, water gets
in the cracks, when
that water expands
the rock is crunched
instead of breaking
apart.
 The
pictures in this article are from the
summit ridge of Ypsilon Mountain,
perhaps one of the best spots in the park
to see the effects of frost wedging. You
can clearly see in these pictures how the
rocks were split apart into plates -- a
sure sign of frost wedging at work.
What is Salt Wedging?
SALT
WEDGING. When it rains
and water flows everywhere, it
usually have ions and salts
dissolved inside.
The water flows in a rock and
evaporates. Slowly crystals begin to
grow, those crystals act like a wedge
and crack the rocks.
A wooden post that soaked for many
years in a pool of brine in Owens Lake
(dry), eastern California. The grotesque
swelling of the wood results from
deposition of salts in the wood.
Ok, but what is Chemical
Weathering then?
The
breaking
down of rocks
by changing
the molecular
make up of
the rock.
http://www.geography4kids.com/files/land_weathering.html
But how does this chemical
weathering make the changes?
Through
the
process of…
Oxidation
Hydrolysis
carbonization
What do you mean by
oxidation?
The
process by which oxygen
combine with water and
minerals in the rock such as
calcium and magnesium.
When iron reacts with oxygen,
reddish -brown iron oxide is
formed. The iron-oxide crust
crumbles easily and weakens
the rock.
Oxidation Continued
Oxygen
forms with metal
to produce a compound.
Then what is hydrolysis?

HYDROLYSIS is…
chemical
reaction between the
minerals in the rock and
hydrogen in rain water.
For example, during hydrolysis,
the feldspar in granite changes
to clay mineral which crumbles
easily, weakening the rock and
causing it to break down.
What is carbonization?
process
by which dissolved carbon
dioxide in rainwater or moisture
in surrounding air forms carbonic
acid and reacts with the minerals
in the rock.
This process weakens the rock
thus breaking it down in the
process.
What is Erosion?
wearing
away of
rock: the gradual
wearing away of
rock or soil by
physical
breakdown,
chemical solution,
and transportation
of material
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