Weathering breaks down rocks into smaller pieces through physical or chemical processes. Physical weathering mechanically breaks rocks apart through frost wedging, friction, or animal burrowing. Chemical weathering uses chemical reactions to break rocks down, aided by water, oxygen, carbon dioxide, living organisms, and acid rain. Carbon dioxide dissolves in water to form carbonic acid, which chemically weathers limestone. Biological weathering also contributes through plant roots penetrating rocks and animal burrowing.

1. Weathering and Erosion

2. Weathering
The breakdown do the materials of
Earth’s crust into smaller pieces.

3. Physical Weathering
• Process by which rocks are broken
down into smaller pieces by external
conditions.
Types of Physical Weathering
• Frost heaving and Frost wedging
• Friction and impact
• Burrowing of animals

4. Frost Wedging

5. Friction and Repeated Impact

6. Temperature Changes

7. Chemical Weathering
• The process that breaks down rock
through chemical changes.
The agents of chemical weathering
– Water
– Oxygen
– Carbon dioxide
– Living organisms
– Acid rain

8. Water
• Water weathers rock by dissolving it

9. Oxygen
• Iron combines with
oxygen in the presence of
water in a processes
called oxidation
• The product of oxidation
is rust

10. Carbon Dioxide
• CO2 dissolves in rain water and creates
carbonic acid
• Carbonic acid easily weathers limestone and
marble

11. Carbon Dioxide
• CO2 dissolves in rain water and creates
carbonic acid
• Carbonic acid easily weathers limestone and
marble

12. Living Organisms
• Lichens that grow on rocks produce weak
acids that chemically weather rock

13. Acid Rain
• Compounds from burning coal, oil and gas
react chemically with water forming acids.
• Acid rain causes very rapid chemical
weathering

14. BIOLOGICAL WEATHERING
The breakdown of rock materials through
certain biological actions such as penetration
of plant roots,burrowing of animals.
TYPES OF BIOLOGICAL WEATHERING
 By plant roots
 Burrowing of animals

15. Plant Roots

16. Burrowing of Animals