1. External Forces of Change
Weathering & Erosion

2. 1. Explain the difference b/w weathering & erosion.
Weathering breaks down rocks on Earth’s surface into smaller pieces
Erosion wears away Earth’s surface (wind, glaciers, moving water)

3. Physical- breaks rock into smaller pieces
2. Explain the difference b/w physical & chemical weathering; give example.
Physical- breaks rock into smaller pieces
Water freezes in crack, ice splits rock

4. Chemical- changes the actual chemical make-up of the rock
2. Explain the difference b/w physical & chemical weathering; give example.
Chemical- changes the actual chemical make-up of the rock
Water + CO2 destruction of limestone

5. 3. What causes acid rain?
Acidic chemicals from pollution (factories, etc) combine w/ precipitation
Eats away at buildings, kills fish/plants, etc.

6. 4. What is wind erosion? 5. Benefits & drawbacks?
Movement of dust, sand, soil from one place to another
Benefits: Mineral-rich soil is deposited creating fertile soil
Drawbacks: Good soil can be carried away leaving land barren

7. Ex: LOESS.
Fertile, yellow-gray soil carried by wind throughout the Yellow River leaving the land great for farming

8. 7. How can glaciers cause erosion?
Slowly move downhill p.u. soil/rocks destroy forests, carve valleys, alter river course, wear down mtns.

9. 8. What are moraines?
Large piles of debris/rocks left behind by glaciers
Form long ridges of land or create dams that form glacial lakes

11. 9. Describe the difference b/w sheet glaciers and mtn. glaciers.
Sheet: flat, broad sheets of ice (Greenland, Antarctica)
Can break
off to form icebergs
Mtn: found in high mts. (Rockies)
Move downhill creating valleys

12. 10. How does water cause erosion?
Fast-moving water  cuts into land, wears away soil/rock  creates sediment which grinds away other rocks
Waves erode cliffs, beaches, etc.

13. wind and little water erosion
1. Bryce Canyon, Utah
wind and little water erosion

14. 2. Grand Canyon, Arizona
water erosion

15. 3. Glacier National Park, Montana
glacial erosion

16. 4. Bronze turning green when exposed to elements
chemical weathering – acid rain

17. 5. Broken tombstone
physical weathering

18. chemical weathering (carbonic acid)
6. Mammoth Cave, Kentucky
chemical weathering (carbonic acid)

19. 7. Grand Tetons, Wyoming
glacial erosion

20. 8. Trees atop Mt. Mitchell, North Carolina
chemical weathering (acid rain)

21. 9. Capital Gorge, Utah
wind and water erosion

22. The Great Lakes – NE U.S.
glacial erosion