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Mechanical Weathering
Mackenzie
Kevin
Matt
Sam
Marissa
Veronica
Mechanical Weathering
• Mechanical weathering includes several
processes that break rock into smaller
pieces. (physical disintegration)
Types
• Mechanical weathering is broken down
into two main categories frost action and
pressure release
Frost Wedging
• The expansion of freezing water in rock
cracks which push the rock further apart
• Water in cracks can expand as much as
9%
• Leads to further cracking or parts of the
rock splitting off
Frost Heaving
• Lifts rock and soil
upwards
• Ice forms under
boulders and
expands which
pushes them
upwards
• Causes cracks in
roads during winter
time
Pressure Release
• Tectonic uplift causes rocks to near the
surface of the earth crust
• As they near a pressure change occurs
due to the removal of weight (other rocks
on top)
• The removal of weight allows for the
granite to expand upwards
Sheet Joints
• Formed be pressure release
• Outer part of the rock expands more then the
inner part
• These “sheets” of rock can break off due to
gravity forming concentric slabs, this is
known as exfoliation
Biological Activity
• Plant growth such
as growing roots
can lead to the
cracking of rocks
• Burrowing animals
can also have an
effect on rocks
Salt Crystals ( Haloclasty)
• As water
evaporates in small
cracks of rocks salt
crystals can form
• These salt crystals
exert pressure due
to their expanded
form, helps
disintegrate
• Occurs in desert
climates
Abrasion
• The process of breaking and chipping
away at rocks caused by the impact of
other matter (grinding together, smashing
etc)
Erosion
• Erosion is caused by wind, rain and other
processes or things which breaks down
the surface of the Earth or rocks.
Pressure Release
Frost Heaving
Frost Wedging
Exfoliation
Sheet Joints
Erosion
Haloclasty
Abrasion
-Uplift of rocks caused by
ice
-Splitting apart of rock by ice
-Can break off due to gravity
-The breaking of rocks
caused by impact of other
object
-Process of spalling off rock
layers
-The expansion of rocks due
to the removal of weight
on top
-Disintegration of rock
(occurs in desert
climates)
- The process of breaking
things down