1. 8-1 Rocks and Weathering
How do rocks and weathering affect Earth’s surface?
What are the causes of mechanical weathering ands chemical weathering?
What determines how fast weathering occurs?

2. How do arches form?

3. Define: “Weathering”
“Weathering” is the process that breaks down rock on Earth’s Surface.

4. Erosion
“Erosion” is the removal of rock particles by wind, water, or gravity.

5. Uniformitarianism the processes that operate today are
is the principle that
the processes that
operate today are
the same processes
that operated in
the past.

6. Mechanical Weathering
The type of weathering that breaks rocks into smaller pieces.

7. Chemical Weathering
“Chemical Weathering” is the type of weathering that breaks down rock through chemical changes.

8. Types of Mechanical Weathering
Release of Pressure
Freezing and Thawing
Animal Actions
Plant Growth
Abrasion

9. Release of Pressure
Erosion removes material from the surface of a mass of rock, this reduces pressure on the rock and causes it to crack.

10. Freezing and Thawing
When water freezes in cracks in a rock it expands and makes the crack bigger, this is called “Ice Wedging”

11. Animal Actions Animals that burrow break up rock and soil.
Their burrowing also exposes more rock to weathering.

12. Plant Growth
The roots of trees and other plants enter cracks in rock. As the plant grows its roots force the crack to widen.

13. Abrasion
Sand or rock particles carried by wind or water wear away at rock.
This is similar to sandpaper being used on wood.

14. Chemical Weathering
The types of chemical weathering include the action of water, oxygen, carbon dioxide, living organisms and acid rain.

15. Living Organisms
Plant roots can produce weak acids that wear away rock.
Lichens for example.

16. Acid Rain
Compounds from fossil fuels can mix with water in the atmosphere and come down as acid rain.
This causes rapid chemical weathering.

17. Action of Water Most important cause of chemical weathering
Water dissolves rock making a solution.

18. Oxygen
Oxygen combined with water will cause iron to undergo Oxidation otherwise known as rust.

19. Carbon Dioxide
Carbon dioxide can dissolve into rainwater and create a weak acid called Carbonic acid.
This weak acid easily weathers marble and limestone.

20. Rate of Weathering
Type of Rock and the climate affect the rate of weathering.
Some rocks are more permeable and weather faster.
Chemical weathering occurs more quickly in warm climates.