1. Aim: How does the shape of Earth’s surface change?
Weathering
Aim: How does the shape of Earth’s surface change?

2. Do Now: List a few examples
Physical Changes
Chemical Changes

3. Vocabulary Surface processes Physical weathering Chemical Weathering
Biological Weathering
Erosion
Ice wedging
Abrasion
Exfoliation
Textbook

4. Do Now: Compare the 2 obelisk pictures.

5. A. Weathering:
1.Physical and chemical processes that break down and change the shape of rock on Earth’s surface.
a. Physical weathering = mechanical forces
b. Chemical weathering = chemical changes weaken the rock
2. Physical and chemical weathering often occur at the same time.

6. B. What is the difference between weathering and erosion?
Weathering breaks down rock and erosion carries the pieces away.
Weathering and erosion work together to change Earth’s surface.
The result of weathering is sediments, a step in the formation of sedimentary rock.

7. C. What happens during physical (mechanical) weathering?
1. The rock is:
a. broken into smaller pieces
b. peeled or cracked
c. edges are worn down
2. The rock is the same type, but changed in size and shape.

8. D. Types of physical weathering
1. Repeated freezing and thawing (melting) of ice/water called ice wedging or frost wedging
2. Plant growth in cracks of rocks
3. Animal action – digging or burrowing
4. Abrasion grinding away of rock by water, wind, ice or gravity.
5. Heating and Cooling – continually rising to high and low temperatures, can cause exfoliation (peeling) of rock layers

9. Frost or Ice Wedging
Ice wedging – repeated freezing and thawing of ice in cracks of rocks eventually splits the rock.

10. E. Why does water break open rocks when it freezes?
Water is the only substance on earth that expands (gets bigger) when it freezes!
Explain why ice floats….

11. Plant wedging – seeds can drop into cracks in rocks and grow… eventually splitting the rock.

12. Heating/Cooling or freeze/thawing can crack roads

13. Exfoliation after repeated freeze/thaw, heat/cool or ice wedging

14. Abrasion – sharp edges get worn down and smoothed by water

15. Abrasion by wind…like a sandblaster

16. F. What does a rock look like that weathered in water?
1. Rocks weathered in water are often rounded and smooth because of abrasion in running water.
2. Fact - Water causes more weathering and erosion than another other thing on earth.

17. G. What do gravity and glaciers do to rocks?
Abrasion by gravity and glaciers breaks rocks into jagged pieces.

18. H. Mountains…compare the 2.
Which is more weathered?

19. Down fell a face The Old Man in the Mountain…. Weathered away!
Of a million years counting
The king of the mountain
And guard of the valley below
The last generation
The very last era
Never to see again
5/3/03
Weathered away!

20. Which layer has been weathered most? Least?6 1 3 5 2 4

21. Summary:
What types of physical weathering might have contributed to the Old Man’s demise?
What climate conditions must exist for ice wedging to occur?
Which types of physical weathering could also be considered organic or biological?

22. Which weathering agents might have changed Cleopatra’s needle?