1. Weathering and Erosion
Outcome E5: Describe the impact of a change to the Earth’s surface or atmosphere on organisms
Weathering and Erosion

2. Where do soil, sand, pebbles and boulders come from?
Big rocks are broken into smaller pieces.
They are broken down by nature and by man’s actions.
This can be bad for the environment.

4. Definitions
Weathering is the process of breaking rocks down into smaller pieces.
Erosion is the movement of sediment by wind and water.

5. Types of weathering
Physical/Mechanical weathering is when rocks break into smaller pieces.
Waves crashing on rocky shores.

6. When water freezes, it expands and can crack rocks.
Sand carried by wind and water acts like sandpaper.

7. Farming and drought loosens the soil and can speed up erosion by the wind.

8. Questions 1-3, page 319
1. Clarify the meanings of the following terms:
a. soil-
b. decomposition-
c. weathering-
d. sediment-
2. Explain the difference between erosion and weathering.
3. Describe what happens to water when it freezes.

9. Answers 1. Clarify the meanings of the following terms:
a. soil- the upper layer of earth in which plants grow.
b. decomposition- to be broken down by natural processes.
c. weathering- process of breaking rocks down into smaller pieces
d. sediment- Sand from the weathering of rock that is carried and deposited by wind, water, or ice.

10. 2. Explain the difference between erosion and weathering.
Weathering is the process of breaking rocks down into smaller pieces and erosion is the movement of sediment by wind and water.
3. Describe what happens to water when it freezes.
It becomes solid ice and expands.

11. Types of weathering
2. Chemical weathering is when rocks are changed into new substances by chemical reactions with water or gases.
Acid rain is formed when air pollution (from fossil fuels) dissolves in rain water.

12. Acid rain Acid rain speeds up the process of chemical weathering.
Dissolves statues and buildings made of rocks like marble.

13. Kills animals in rivers and lakes.
Kills forests, leading to erosion.

14. Makes soil too acidic for plants and crops to grow.

16. Types of weathering
3. Biological weathering is when rocks are broken down due to living things.
Animals scratch and break apart
rocks.

17. As plants grow, their roots force the cracks in rocks wider until the rock breaks.

18. Questions 4-6, page 319
4. Identify three causes of: a. mechanical weathering b. biological weathering 5. Identify three different ways in which rocks are weathered. 6. Identify four ways in which weathered material can be moved.

19. Answers
4. Identify three causes of: a. mechanical weathering 1-Waves on the rocky shore. 2-Ice cracking rocks. 3-Sediment acts like sandpaper. b. biological weathering 1-Animals burrowing. 2-Tree roots break rocks. 3-Plants secrete acids.

20. 5. Identify three different ways in which rocks are weathered.
1-Physical/mechanical weathering.
2-Chemical weathering.
3-Biological weathering.

21. Identify four ways in which weathered material can be moved.
1-Wind
2-Water from rain
3-Water from rivers
4-Ice glaciers

22. People and erosion
Humans have changed the surface of the Earth very much in the last 200 years.
We build inventions that need natural resources that we mine from the ground.

23. We have physically broken rocks down
By mining
by using explosives
by landscaping (roads, houses and cities)

24. Exhaust gases from cars and factories create pollution and acid rain
Exhaust gases from cars and factories create pollution and acid rain. These can chemically weather away rock on mountainsides and buildings.

25. Construction, landscaping and ploughing on farms change how water and wind flow. Without careful planning, this can increase erosion.

26. Roots help to hold the soil and slow down erosion
Roots help to hold the soil and slow down erosion. Drought, overgrazing and deforestation remove plants and increase erosion.

27. Questions 7-10, page 319
7. Explain two ways in which humans and science have accelerated weathering. 8. Identify the chemical released into the air that speeds up chemical weathering. 9. Explain how this chemical gets into the air. 10. Describe how acid rain speeds up chemical weathering.

28. Answers
7. Explain two ways in which humans and science have accelerated weathering.
Mining
Construction
8. Identify the chemical released into the air that speeds up chemical weathering.
Sulphur dioxide.

29. 9. Explain how this chemical gets into the air
9. Explain how this chemical gets into the air. Pollution from factories and cars. 10. Describe how acid rain speeds up chemical weathering. The acid dissolves rocks.

30. What can we do?
People have sped up erosion and weathering, which is bad. We need to do something to protect the environment.

31. Control how water flows to reduce erosion. E. g
Control how water flows to reduce erosion. E.g. Contour ploughing on farms, gutters and sealed roads . Livestock numbers need to be controlled in times of drought to stop overgrazing.

32. Wind speed can be reduced by windbreaks and stands of trees
Wind speed can be reduced by windbreaks and stands of trees. Models of structures can be used to see how they will affect erosion before they are built.

33. Walk or ride a bike. Less cars means less acid rain
Walk or ride a bike. Less cars means less acid rain. Modern cars make less pollution. New hybrid cars make even less pollution than normal cars.

34. Industrial chimneys can have ‘scrubbers’ to remove some of the dangerous chemicals so there is less pollution.

35. Questions 7-10, page 319
11. Describe whose responsibility it is to stop the weathering caused by humans. 12. Identify two things that you can personally do, that will help stop or slow weathering and erosion.

36. Answers
11. Describe whose responsibility it is to stop the weathering caused by humans. It is our responsibility. 12. Identify two things that you can personally do, that will help stop or slow weathering and erosion. Ride a bike or walk to school. Plant more trees.