Amazing Ice Glaciers and Ice Ages Exam Prep Chapter 18

CHAPTER 18: Amazing Ice: Glaciers and Ice Ages

LEARNING OBJECTIVES

18A. Describe how glacial ice forms and flows, and how to categorize various kinds of glaciers.

18B. Explain why glaciers advance and retreat, and how their flow modifies the landscape.

18C. Recognize sedimentary deposits and associated landforms left by glaciers.

18D. Describe evidence showing that glaciers covered large areas of continents during the Pleistocene Ice Age, and that there have been four or five earlier ice ages during Earth history.

18E. Suggest why ice ages happen, and why glaciations during an ice age occur periodically.

MULTIPLE CHOICE

1. Boulders left behind by glacial ice, such as these on a hillside in Wyoming, are known as __________.

2. Glacial deposits consist primarily of __________.

3. Which of the following statements is true of flowing water and glacial ice?

4. The last ice age, or time that glaciers covered areas that today have temperate climates, ended ________ years ago.

5. At the present, glaciers cover about ________ of the surface of the continents.

6. Today, continental glaciers are limited to Antarctica and ________.

7. An intermediate product in the transformation of snow to glacial ice is ________.

8. When glacial ice directly evaporates into vapor without melting into liquid water, it is said to be

9. During the last ice age, a ________ glacier covered much of the northern United States.

10. What type of glacier is seen in the foreground of the following picture?

11. At depths of greater than 60 m, ice moves by plastic deformation. What causes this transition from brittle to ductile behavior?

12. Glacial ice exhibits ________ behavior near the top but ________ behavior at a depth of more than 60 m.

13. Large cracks in the surface of glaciers that extend down to the depth where the ice can behave plastically are called

14. Which of the following best describes the direction that glaciers and ice sheets can flow?

15. A glacier will always advance from its source area if the rate of accumulation is greater than the rate of ________.

16. The speed at which ice in a glacier moves is slowest along the sides and bottom due to

17. The polar ice caps on Mars are an example of what type of glacier?

18. Cirques and horns are features associated with ________.

19. A bowl-shaped depression formed by a mountain glacier is termed a(n) ________.

20. What kind of information do glacial striations reveal about past glaciers?

21. Valleys carved by glaciers tend to be shaped like the letter ________, whereas valleys carved by water tend to be shaped like the letter ________.

22. A hanging valley is formed when a ________.

23. When the sea level rises, causing the ocean to fill a glacially carved valley, a ________ results.

24. Which of the following types of glaciers is most likely to carve features such as horns, cirques, and aretes?

25. What kind of information does a roche moutonnée reveal?

26. Stratified sorted sand and gravel are deposited by ________.

27. Sediments deposited directly by glaciers as they melt are characterized by ________.

28. Sediments deposited directly by glaciers as they melt are ________.

29. Wind blows finer particles long distances from glacial environments, where they settle out to form ________.

30. What types of moraines are shown as the dark stripes in the figure below?

31. If glaciers carry a mixture of different clast sizes, why are glacial outwash deposits layered?

32. What is glacial drift?

33. If you wander around Central Park in New York City, you will eventually encounter random, large boulders that are made of a type of rock not found in the area. How did these large boulders get to Central Park?

34. In the figure below, which letter corresponds to an esker?

35. Which letter corresponds to the furthest reach of the glacier in the figure below?

36. Which letter corresponds to where sorted and layered glacial sediments would occur on this landscape?

37. Cape Cod and Long Island are large examples of what type of features left behind on landscapes after retreat of glaciers?

38. Underneath their thick ice sheets, the land surfaces of Greenland and Antarctica are

39. The weight of a large ice sheets causes

40. A(n) ________ in global sea level is ultimately the result of a ________ event.

41. How long does postglacial rebound take after continental ice sheets melt?

42. What do shorelines of former pluvial lakes in the western United States reveal?

43. During the Pleistocene Ice Age, all the climate belts of the northern hemisphere shifted to the __________.

44. The Earth’s most recent ice age is called the ________ and began approximately ________ years ago.

45. The Milankovitch cycles describe the change in ________ caused by cyclical changes in the Earth’s orbit around the Sun.

46. Imagine that you live in a hot and sunny climate. Painting your roof white would help ________ your house by ________ the albedo.

47. The loss of rainforests would ________ the greenhouse gases, thereby ________ global warming.

48. An important long-term factor that determines whether glacial ice will form on a continent has likely been the proportion of which gas in the atmosphere?

49. The effect of periodic changes in the Earth’s orbital eccentricity and magnitude and direction (precession) of its axial tilt on the advance and retreat of ice sheets was first proposed by ________.

50. By increasing the albedo of the Earth, global ice sheets produce conditions that are ________ to their further advance, thus providing an example of ________ feedback.

1. Label the four different types of mountain glaciers shown in the picture below.

2. What are the circumstances that lead to glacial advance versus glacial retreat? Most glaciers today are in retreat. What does this imply about the glaciers and their environment?

3. Contrast a glacially carved valley with one carved by a river.

4. Notice the boulders in the center of this picture of a glacially formed landscape. What are they? How did they get there?

5. Describe what you would expect to see in a deposit of glacial till deposit. Why?

6. Explain why the deposits made by glacial outwash are stratified.

7. Contrast global sea level during times of increased glaciation versus interglacial periods, and explain why this occurs.

8. You and some friends are going on a road trip and one of your goals is to see a glacier. Where could you go in the continental United States to do this? What type of glacier will you most likely be visiting?

9. Imagine you are living in your current home but during the Pleistocene Ice Age. Contrast the present climate with that of your new climate in the Pleistocene. In one sentence, summarize how the climate is different now.

10. List and describe one short-term cause for glaciations.