1. Weathering

2. Weathering
Weathering is the process that breaks down rock and other substances at the Earth’s surface.
There are 2 types of weathering: mechanical and chemical.

3. Mechanical Weathering
Mechanical weathering is where rock is physically broken down into smaller pieces.
There are 5 agents for this type of weathering:
Abrasion
Freezing & thawing
Heating & cooling
Plant growth
Animal activity

4. Abrasion is the grinding away of rock by rock particles carried by water, ice, wind or gravity.
2. Freezing & thawing-as water freezes and thaws in cracks of rocks, it causes the cracks to widen and deepen (ice wedging).
3. Heating & cooling-sun, forest fire and rain can heat and cool a rock causing it to break.
4. Plant growth- roots of plants enter cracks in rocks, as roots grow, they force the cracks farther apart.
5. Animal activity-animals that burrow loosen and break apart rocks and soil.

5. Chemical Weathering
Chemical weathering is when rock is broken down through chemical changes.
There are 5 agents for chemical weathering:
Water
Oxygen
Carbon dioxide
Living organisms
Acid rain

6. Water- dissolves rock
2. Oxygen- causes rocks that contain iron to rust (oxidation).
3. Carbon Dioxide- forms carbonic acid with rain that weathers marble and limestone.
Living Organisms- plant roots and lichens produce weak acids that weather rock.
5. Acid rain- pollutants in the air react with water vapor.

7. The rate of weathering is how fast weathering takes place
The rate of weathering is how fast weathering takes place. It is determined by the type of rock and climate.
A stable rock is one that has minerals that are resistant to chemical weathering.
The more moisture there is in an area, the more quickly the rock will weather.

8. The end…
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