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Chapter 6

GEOL 1010 Chapter Notes - Chapter 6: Frost Heaving, Weathering, Eluvium

Geological Sciences
Course Code
GEOL 1010
Pamela Stephens

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Geology Chapter 6 Key Terms
Weathering involves the physical breakdown (disintegration) and chemical alteration
(decomposition) of rocks at or near the Earth’s surface
Mechanical weathering is when physical forces break rock into smaller and smaller pieces
without changing the rock’s mineral composition. Mechanical weathering increases the surface
area available for chemical weathering.
Chemical weathering is when a rock undergoes a chemical transformation and transforms the
rock into new compounds
An example provided by the book is a log. A log undergoes mechanical weathering if it
disintegrates into smaller pieces, it undergoes chemical weathering if it catches on fire and
turns into ashes.
Frost wedging is a type of mechanical weathering. It occurs after water works its way into the
cracks of rock, then the freezing water enlarges the cracks and angular fragments are produced.
Most mechanical weathering is frost wedging but there are other important kinds.
Frost heaving is a kind of frost wedging that occurs in soil. The soil seeps into the cracks of rock
and when the soil freezes, it expands the cracks in rock, causing the rock to weaken over time.
Sheeting is a mechanical weathering process that is characterized by the splitting off of slab-like
sheets of rock.
Unloading is the reduction of pressure that occurs as the underlying rock is removed.
Exfoliation dome is what occurs after excessive weathering causing the slabs to separate and
break off
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