weathering and erosion
TRANSCRIPT
Weathering is the
breaking down of
rocks, soil and
minerals as well as
artificial materials
through contact
with the Earth's
atmosphere, biota
and waters.
Temperature
Rainfall
Plants
Animals
Physical
Weathering
Chemical
Weathering
Biological
Weathering
Physical
weathering, also
known as
mechanical
weathering, is the
class of processes
that causes the
disintegration of
rocks without
chemical change.
Expansion and contraction
of rocks is caused by
temperature changes. As
some minerals expand more
than others, temperature
changes set up differential
stresses that eventually
cause the rock to crack
apart. Because the outer
surface of a rock is often
warmer or colder than the
more protected inner
portions, some rocks may
weather by exfoliation – the
peeling away of outer
layers.
Severe frost shattering
produces huge piles of
rock fragments called
scree which may be
located at the foot of
mountain areas or
along slopes. Frost
weathering is common
in mountain areas
where the temperature
is around the freezing
point of water.
In pressure release,
also known as
unloading, overlying
materials (not
necessarily rocks)
are removed (by
erosion, or other
processes), which
causes underlying
rocks to expand and
fracture parallel to
Chemical weathering
changes the
composition of rocks,
often transforming them
when water interacts
with minerals to create
various chemical
reactions. Chemical
weathering is a gradual
and ongoing process as
the mineralogy of the
rock adjusts to the near
surface environment.
Within the weathering
environment chemical
oxidation of a variety of
metals occurs. The
most commonly
observed is the
oxidation of Fe2+ (iron)
and combination with
oxygen and water to
form Fe3+ hydroxides
and oxides such as
goethite, limonite, and
hematite.
Rainfall is acidic
because atmospheric
carbon dioxide
dissolves in the
rainwater producing
weak carbonic acid. In
unpolluted
environments, the
rainfall pH is around 5.6.
Acid rain occurs when
gases such as sulfur
dioxide and nitrogen
oxides are present in
A number of plants and
animals may create
chemical weathering
through release of
acidic compounds, i.e.
the effect of moss
growing on roofs is
classed as weathering.
Mineral weathering can
also be initiated and/or
accelerated by soil
micro-organisms.
In geomorphology
and geology, erosion
is the action of
exogenic processes
(such as water flow or
wind) which remove
soil and rock from one
location on the Earth's
crust, then transport it
to another location
where it is deposited.
Flowing Water
Wind
Sea Waves
Formation of
Components of
Soil
Construction
Materials
Landscapes
People Killed by
Flowing Water
Damage to
Human
Activities
Damage to
Buildings
Information:
International Lower
Secondary
Geography 3
The Big Book of
Knowledge
Wikipedia
Pictures:
Google Images