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Notes: Weathering and Erosion – Study Questions
1. What is weathering?
The breaking down of rock
2. What is mechanical (physical) weathering?
Disintegration; weathering with no change in composition
3. What is chemical weathering?
Decomposition; weathering when rock changes into different substances through chemical reactions
4. What is weathering by solution?
Water dissolves minerals by breaking them down into their ions and carrying them away
5. What is abrasion?
moving sand, pebbles, etc. in the wind or water grind against other rocks as they move
6. What is frost wedging?
Breaking and fracturing of rock when water seeps into cracks in a rock and then freezes and expands. Crack
widens with repeated cycles of freezing and thawing
7. What is hydrolysis?
Water broken down into hydrogen and hydroxide (OH) ions reacts with minerals creating new minerals
8. What is oxidation?
Minerals react with and combine with oxygen
9. What is splash erosion?
The impact of water breaks down rock
10. How do plant acids cause weathering?
Lichens (and other plants) secrete acidic substances that dissolve and react with minerals
11. What is carbonation?
Carbon dioxide reacts with water to form carbonic acid – raises the pH of water
12. What is exfoliation?
Released pressure from removal of rock from above causes it to break along curved joints in sheets
13. How do plant roots and burrowing animals cause weathering?
Animals and plants wedge into cracks in rock causing widening of the crack and further cracks
14. What is acid rain?
Sulfur emitted by factories reacts with cloud droplets/rain creating sulfuric acid raising the pH of the rain
15. What is hydration?
Minerals combine with the H2O molecule causing the mineral to soften
16. How does wetting and drying cause weathering?
Rock fractures when absorbing (expands) and losing(contracts) water
17. How does heating and cooling cause weathering?
Rock fractures when heating (expands) and cooling (contracts) quickly
18. Which of the above examples of weathering are mechanical?
Frost wedging, splash erosion, abrasion, burrowing animals and plant roots, exfoliation, wetting and drying,
heating and cooling
19. Which of the above examples of weathering are chemical?
Hydrolysis, oxidation, plant acids, acid rain, carbonation, solution, hydration
20. What is erosion?
The movement of weathered materials
21. What are the 5 primary forces of erosion?
1. Gravity
2. Running Water
3. Glaciers
4. Wind
5. People and Animals