1. Chapter 5 Weathering, Soils, & Mass Movements

2. What do you know? What process breaks down rock into smaller pieces?
A.) cementation
B.) compaction
C.) weathering
D.) deposition
Answer –
C.) weathering

3. What do you know? Which of the following are types of weathering?
Mechanical?
Chemical?
Answer: Both are forms of weathering

4. Mechanical Weathering
Mechanical weathering occurs when physical forces break rock into smaller and smaller pieces without changing the rock’s mineral composition
Each piece has the same characteristics as the original rock

5. Mechanical Weathering
Mechanical Weathering Animation
Mechanical Weathering
Surface area increases as breakup a rock

6. Mechanical Weathering of Rocks 3 types1 2
Uploading
Frost wedging 3
Root wedging

7. 1. Uploading Large masses of igneous rock are
exposed through uplifting and erosion
of overlying rocks

8. 2. Frost Wedging
The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices
Sections of rock that are wedged loose and fall apart
Frost Wedging Animation
Can of coke explodes when it is frozen!

9. Frost Wedging

10. 3. Biological Activity
Plant roots can grow into cracks in rock and wedge the rock apart as they grow
Burrowing animals move rocks to the surface, where weathering is more rapid

11. Chemical Weathering
Chemical weathering is the transformation of rock into one or more new compounds
If I gave you a piece of paper, how would you show me mechanical weathering?
How would you then show me chemical weathering?

12. Chemical Weathering Water Most important agent in chemical weathering
i.e. Oxygen dissolved in water reacts easily with certain minerals

13. Chemical Weathering Iron on barrels coverts to rust
Iron + oxygen (from air) coverts to iron oxide (rust)

14. Chemical Weathering
Rain water mixes sulfur & nitrogen produced from the burning fossil fuels- coal & gasoline
Forming acid rain

15. Chemical Weathering “Acid Rain”
Acid rain accelerates the chemical weathering of stone monuments and structures

16. Chemical Weathering Exposure to moisture and
oxygen turns the copper into
copper sulfate which is green
in color.