Weathering
Weathering – the process by which rock materials are broken down by the action of physical or
chemical processes
Mechanical weathering – the breakdown of rock into smaller pieces by physical means
Abrasion – is the grinding and wearing away of rock surfaces through the mechanical action of
other rock or sand particles
Chemical weathering – the process by which rocks break down as a result of chemical reactions
Acid precipitation – rain, sleet, or snow that contains a high concentration of acid
Section Review
2. Which of the following things cannot cause mechanical weathering?
b. acid
3. List three things that cause chemical weathering of rocks.
water, acids, and air
4. Describe three ways abrasion occurs in nature.
wind, water, and gravity
5. Describe the similarity in the ways tree roots and ice mechanically weather rock.
Both tree roots and ice can force cracks in rock to expand.
6. Describe five sources of chemical weathering.
water, acid precipitation, acids in groundwater, acids in living things, and air
7. Why does acid precipitation weather rocks faster than normal precipitation?
Acid precipitation is more acidic than natural precipitation. Stronger acids break down
rocks faster.
8. Compare the weather processes that affect a rock on top of a mountain and a rock buried
beneath the ground.
Only the rock on the surface experiences weathering, since it is exposed to wind,
precipitation, and gravity.