Physical WeatheringMechanical weathering, also called physical
weathering, is one type of
weathering which is “the gradual breakdown of rock to sand, and then to silt,
or powdered rock, and finally to clay through physical means” (North American
Montessori, n.d., para. 3). Many
different things can cause the processes of physical weathering. Heat and cold
create cracks in rocks do to the minerals in the rocks expanding and shrinking
(North American Montessori Center, n.d.); this process is called thermal
expansion (Processes of Change, 2010c). When cracks form in the rocks, water
can get in and freeze, expanding it and eventually splitting the rock (National
Geographic, n.d.b; North American Montessori Center, n.d.; Processes of Change,
2010c; Van Rose, 1994). This type of physical weathering is called ice or frost
wedging (Processes of Change, 2010c). Sand can be formed if rocks are pressed
against each other by the ocean and the outside of the rocks become smooth
enough. Sand itself can wear rocks by acting as sand paper (North American
Montessori Center, n.d.). Unloading is another type which is mostly
the work of erosion. Unloading is when soil or rock stratum is removed and
trapping pressure on the rock. As time passes, the rock breaks into sheets with
the pressure (Processes of Change, 2010c).
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Physical Weathering by:
Salt Salt is another way of breaking down a rock. Salt
water gets into rocks and when it evaporates salt crystals are left and their
growth is what breaks down the rocks.
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Root Wedging
Root wedging is when plants grow in
the fractures of rocks eventually breaking the whole rock as the plant grows
(Processes of Change, 2010c). An example can be a plant as small as a moss
getting into tiny cracks in rocks.
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Animals Animals, such as rabbits and badgers, also
contribute when they dig aboveground and little by little the rock crumbles
(National Geographic, n.d.b; Van Rose, 1994).
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