Transcript Weathering

Weathering
What is weathering?
• Weathering is 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.
1. Ice – Freezing and Thawing make rocks
expand and contract = creates cracks
2. Abrasion – Grinding and wearing away of rock
= rubbing against another surface
Mechanical Weathering
3. Wind, water, and gravity• Wind blows sand against rock
• Water rolls pebbles against the
bottom of rivers or streams
• Gravity causes rock to fall on top
of each other
4. Plants – roots get into rocks and
crack them
5. Animals – burrow through the soil
Chemical Weathering
•
1.
2.
3.
4.
5.
Rocks break down due to chemical reactions
Water – dissolves minerals
Acid Precipitation – acid dissolves rocks.
Groundwater acid – dissolves rock underground
(creates caves)
Acids in living things – Lichens produce an acid that
dissolves trees/rocks.
Air – Oxidation/Rust
Differential Weathering
• Softer rocks wear away and leave harder
rocks behind
Example: Devils Tower in Wyoming
The Shape of Rocks
• The larger the surface area, the faster the
weathering will break down the rock
• Smaller fragments break down faster than
larger fragments.
Weathering and Climate
• Chemical weathering is faster in warm,
humid climates. (Oxidation)
• Ice Wedging occurs in cold climates
Weathering and Elevation
• Mountains are exposed to air and water.
Rocks at the top experience more wind,
rain, and ice and will weather faster.
• Steepness of mountains creates faster
weathering because water runs down the
mountain faster and carries sediment with
it.