1. Chapter 2 Section 1 Pages 38 - 45
Rocks and Weathering
Chapter 2 Section 1
Pages

2. Objective: Explain the agents of mechanical and
chemical weathering and analyze the factors
that affect the rate of weathering.
Weathering: The process that breaks down rocks and
other substances at Earth’s surface.
Erosion: Is the movement of rock particles by wind,
water, ice, or gravity.
Uniformitarianism: This principle states that the same
processes that operate today operated in the past.

3. Mechanical Weathering: Breaks rock into smaller pieces.
Freezing and Thawing
Ice Wedging: Wedges of ice in rocks widen and deepen
cracks. With repeated freezing & thawing, cracks expand
until pieces of rock break off.
Release of Pressure
Plant Growth
Animal Actions
Abrasion: The grinding away of rock particles carried by
Water, ice, wind, or gravity.

4. Chemical Weathering: A process that breaks down rock
through chemical changes. It produces rock particles
that have a different mineral make-up from the rock they
came from.
Causes of Chemical Weathering:
Action of water:
Oxygen
Oxidation: When iron combines with oxygen in the
Presence of water. The product of this is RUST.
Carbon Dioxide
Living Organisms
Acid Rain

5. The most important factors that determine the rate at
which weathering occurs are the type of rock and the
climate.
Permeable: A material that is full of tiny, connected air
spaces that allow water to seep through it.
Both chemical and mechanical weathering occur faster
In wet climates.
Chemical reactions occur faster at higher temperatures.
That’s why chemical weathering occurs more quickly in
Hot and wet climates.