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Weathering of Rocks - Lecture

Abrasion is the process that breaks rocks apart without changing their chemical composition by one rock bumping against another, cutting them into smaller particles and causing sharp or jagged edges. Freeze-thaw occurs when water freezes and expands in cracks, eventually breaking rocks apart. Exfoliation breaks rocks apart in layers parallel to the Earth's surface from rapid temperature fluctuations.

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Sharyl Plan Saromines
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73 views21 pages

Weathering of Rocks - Lecture

Abrasion is the process that breaks rocks apart without changing their chemical composition by one rock bumping against another, cutting them into smaller particles and causing sharp or jagged edges. Freeze-thaw occurs when water freezes and expands in cracks, eventually breaking rocks apart. Exfoliation breaks rocks apart in layers parallel to the Earth's surface from rapid temperature fluctuations.

Uploaded by

Sharyl Plan Saromines
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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The process that breaks


rocks apart without
changing their
chemical composition.
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In abrasion, one rock bumps


against another rock. Abrasion cuts
them into smaller particles. It also
causes rocks to have sharp or
jagged edges round-shaped and
smooth.
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Freeze-thaw occurs when water


continually seeps into cracks,
freezes and expands, eventually
breaking the rock apart.
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This type of weathering takes place


when the cracks develop parallel to
the land surface. Rock breaks apart
in layers that are parallel to the
Earth’s surface
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Rapid temperature fluctuations,


such as day-night cycles, cause
rocks to expand and contract. This
causes stress within the rocks and
small cracks form.
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Saline solutions enter the cracks in


a rock and evaporate, leaving behind
salt crystals. As the water
evaporates, salt crystals grow and
accumulate, putting pressure on the
rock and causing it to break apart.
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Chemical weathering is
the weakening and
subsequent
disintegration of rock
by chemical reactions.
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Carbonation is the process of


rock minerals reacting with
carbonic acid. Carbonic acid
is formed when water
combines with carbon
dioxide. Carbonic acid
dissolves or breaks down
minerals in the rock.
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Oxidation is the reaction of


rock minerals with oxygen,
thus changing the mineral
composition of the rock.
When minerals in rock
oxidize, they become less
resistant to weathering.
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Hydrolysis is a chemical
reaction caused by water.
When rocks sit in water for
extended periods of time
they begin to break down
and have a clay-like texture
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Hydration is the absorption


of water into the mineral
structure. Hydration
expands volume and also
results in rock deformation.
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Biological weathering is
the weakening and
subsequent
disintegration of rock
by plants, animals and
microbes.
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➢ Growing plant roots


can exert stress or
pressure on rock.
➢ Plant roots or
microorganisms
produce organic
acids which help
dissolve minerals.
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➢ Microbial activity
breaks down rock
minerals by altering
the rock’s chemical
composition, thus
making it more
susceptible to
weathering.
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➢ Burrowing animals
can move rock
fragments to the
surface, exposing the
rock to more intense
processes and so
indirectly enhancing
the process of rock
weathering.

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