1. The Earth’s Changing Surface
Weathering
The Earth’s Changing Surface

2. Weathering
the process that breaks down rock and other substances at Earth’s surface

4. Erosion
The removal of rock particles by wind, water, ice, or gravity.

5. How fast can it fizz? Place a “rock” into the first beaker
Crush a second “rock” and place it into the second beaker
Add the water to the beaker with the full rock. Time how long it takes for the “rock” to dissolve.
Add the water to the beaker with the crushed “rock.” Time how long it takes to dissolve.

6. How fast can it fizz?
Which dissolved faster, the whole “rock” or the crushed “rock?”
What variable affected how long it took each of them to dissolve?

7. Two Types of Weathering
Mechanical
Chemical

8. Mechanical Weathering
Rock is physically broken into smaller pieces.
These rocks have the same composition as the rocks they came from.

9. Causes of Mechanical Weathering
Ice wedging – freezing and thawing
Causes potholes on streets

10. Causes of Mechanical Weathering
Release of pressure - erosion removes material from surface, pressure is reduced. Pressure release causes rock to crack.

11. Causes of Mechanical Weathering
Plant growth – roots of trees and other plants enter cracks in rocks.

12. Cause of Mechanical Weathering
Actions of animals – animals that burrow in the ground loosen and break apart rocks in the soil.

13. Cause of Mechanical Weathering
Abrasion – the grinding away of rock by rock particles carried by water, ice, wind, or gravity.

14. Chemical Weathering
The process that breaks down rock through chemical changes.
Produces new minerals.

15. Cause of Chemical Weathering
Water – dissolves rock
Water is the most important cause of chemical weathering

16. Cause of Chemical Weathering
Oxygen – rust!!
Iron combines with oxygen in the presence of water in a process called oxidation

17. Cause of Chemical Weathering
Carbon Dioxide – dissolves in rain water
Easily weathers rocks such as marble and limestone

18. Cause of Chemical Weathering
Living Organisms – plants produce weak acids

19. Cause of Chemical Weathering
Acid Rain – how is it formed?
Coal, oil, and gas is burned for energy
These fuels pollute the air with sulfur, carbon, and nitrogen
These compounds react with rainwater, forming acid rain.

21. Walk!!
Re-visit the stops on our previous walk

22. Rate of Weathering Type of Rock Climate
The minerals that make up rock determine how fast it weathers.
Marble vs. granite
Climate
Faster in wet climates
Chemical reactions occur faster at higher temperatures