1. Chapter 6: Weathering and Soil Formation

2. The breaking down of rock and other substances at Earth’s surface is ___.

3. weathering

4. The principle stating that the same processes that operate today also operated in the past is ____.

5. Uniformitarianism

6. Which type of weathering causes the mineral composition of rocks to change?

7. Chemical Weathering

8. What are the most important factors in determining the rate of weathering?

9. Type of rock & Climate

10. What can geologists infer from the rounded, eroded shapes of the Appalachian Mountains?

11. The mountains have been eroding for millions of years.

12. How does ice wedging cause mechanical weathering of rock?

13. Freezing & thawing of water

14. Does weathering occur rapidly or slowly in a hot and wet climate?

15. Rapidly

16. Which agent of mechanical weathering occurs when rock is worn away by the grinding action of other rock particles?

17. Abrasion

18. A rock containing iron becomes soft and crumbly and reddish- brown in color. Which cause of chemical weathering has taken place?

19. Oxygen

20. Why does permeable rock weather easily?

21. Permeable rock contains many small, connected airspaces which allows water to pass through easily.

22. Why are areas of limestone easily eroded by groundwater?

23. Water combines with carbon dioxide as it sinks into the ground, creating carbonic acid, which slowly dissolves the limestone.

24. What begins the process of soil formation?

25. Weathering of bedrock

26. Soil that is rich in humus has high___________.

27. Fertility

28. Soil formation would take place most rapidly with the weathering of ______. A.granite on a mountain top. B.limestone in a desert. C.granite in a cold, dry climate. D.limestone in a warm, wet climate.

30. Why is soil a valuable natural resource?

31. Soil is important to all living things on land.

32. What are the two “jobs” of living organisms in soil?

33. mix the soil & make humus

34. Earthworms add their wastes to the soil, then they die and decay in the soil. They are contributing to the formation of __________.

35. Humus

36. Which of the following would be found in the “B” horizon? A.clay, minerals, and little humus. B.humus only. C.partly weathered rock. D.topsoil.

37. A. clay, minerals, and little humus.

38. Plant growth and animal activity result in which type of weathering?

39. Mechanical weathering

40. Define contour plowing.

41. The practice of plowing fields along curves of a slope.

42. A marble statue is left exposed to the weather. Within a few years, the details on the statue have begun to weather away. What is the cause?

43. Carbonic acid in rainwater

44. In conservation plowing, why do farmers leave dead weeds and stalks of the previous year’s crop in the ground?

45. To retain moisture and hold soil in place