1. Do Now: While watching the following clip answer the following:
1.What is a landform?
2. What is weathering?
3. What is erosion?

2. Learning Objective:
I will be able to explain how weathering and erosion form landscapes.

3. Success Criteria: I can explain weathering.
I can explain mechanical and chemical weathering.
I can explain the agents of weathering.
I can explain the factors that affect weathering.

4. Weathering, Erosion, and Soil
What type of rock is this, how can you tell?

5. Yosemite Valley, California
Mountains Carved by Glaciers

6. Grand Canyon, Arizona
Carved out by the Colorado River

7. Bryce Canyon, Utah Acidic Rainfall has worn away these rocks.
The harder rocks remain standing… but for how long?

8. Weathering The 2 G’s and the 3 W’s
Process by which rocks are broken down
Caused by
Water
Waves
Wind
Gravity
Glaciers
The 2 G’s and the 3 W’s

9. 2 Types of Weathering
A. Mechanical Weathering also called Physical weathering
Rock is broken down into smaller pieces of the same material
(no change in composition)
B. Chemical Weathering
The breakdown or decomposition of rock that occurs when minerals are changed into different substancescomposition)

10. Check for understanding:
Do we understand the difference between mechanical and chemical weathering?

11. Mechanical/Physical Weathering
Frost (Ice) Wedging
Process in which water freezes in the cracks of rock and wedges (pushes) it apart because water expands when it freezes.
Occurs where there are frequent freezes and thaws.

12. Explain what is happening.

13. Frost/Ice Wedging can cause Potholes to form in pavement

14. Mechanical/Physical Weathering
2. Abrasion
The wearing away of rock material by grinding action
Usually caused by sediment in Wind, Water, and Glaciers

15. Wind abrasion- sandblasting effect on stationary rocks as seen here in Arches National Park

16. Mechanical/Physical Weathering
3. Plants and Animals
Plant roots can split rock
Also known as: “Root pry” or “Root action”
Animals dig holes ,breaks up rocks

17. Tree growing out of rock, Shenandoah National Park Tree roots also break up sidewalks

18. Mechanical/Physical Weathering
Exfoliation- gradual peeling of layers due to uplift and frost action, typical of granite domes like those in Yosemite N.P.

19. Exfoliation of Igneous rock

20. Check for Understanding:
Do we understand the agents of physical/mechanical weathering?

21. O2 Chemical Weathering Chemical Weathering
The breakdown or decomposition of rock that occurs when minerals are changed into different substances
(change in composition)
Involves Water ,water vapor, Acids, and/or Oxygen O2

22. Check for Understanding:
Do we understand chemical weathering?

23. Chemical Weathering Hydrolysis
Carbonic Acid in water dissolves Calcite. This chemical weathering can hollow out underground Caverns
Limestone and Dolomite both dissolve because they contain Calcite

24. Acid rain (carbonic acid) weathering the details of statues and tombstones Ex: Marble and Limestone

25. Chemical Weathering Oxidation This is why Mars is the red planet
Oxidation of minerals with iron (magnetite, pyrite) results in the formation of rust or iron oxide.
This is why Mars is the red planet
Copper turns rocks green

26. Check for Understanding:
Do we understand the agents of chemical weathering?

27. Rate of Weathering Surface area Rock composition Climate
How fast a rock weathers depends on 3 factors:
Surface area
Rock composition
Climate

28. Rate of Weathering Surface area
The greater the surface area, the faster the weathering rate
There are more surfaces to be weathered

29. Rate of Weathering Rock composition
Some minerals are more resistant than others
For example, quartz is more resistant (harder) than calcite
Quartz
Calcite

30. Rate of Weathering Climate
(long term pattern of moisture and temperature)
Weathering rates are faster in warm, wet climates
Desert vs. Rainforest

31. Check for Understanding:
Do we understand the factors that affect weathering?

32. Summary:
Success Criteria Recap