1. GLACIERS
CHAPTER 11
GEOLOGY

2. Top 10 glacier facts
10. Approximately 10 percent of the Earth is covered by glaciers; during the last Ice Age, they covered one-third of the Earth’s surface.
9. Glacier ice is the largest reservoir of fresh water on the planet, storing an estimated 75 percent of the world’s supply.
8. Glaciers are found in 47 countries.
7. A glacier can range in length from the equivalent of a football field to more than 100 miles.
6. The Antarctic ice sheet is actually a glacier and has existed for at least 40 million years. If it were to melt in its entirety, sea levels would rise 210 feet worldwide, according to the U.S. Geological Service.

3. 5. Though it sits on the equator, Mount Kilimanjaro is glaciated.
4. On steep slopes, a glacier can be as thin as 50 feet.
3. Mountain valleys are typically “V” shaped before being taken oven by a glacier; during glaciation, the valley widens and deepens and thus becomes “U” shaped.
2. A single glacier ice crystal can grow to be as large as a baseball.
1. Alaska is estimated to have more than 100,000 glaciers. Most remain unnamed

4. World glaciers

6. a thick mass of moving ice
What is a glacier?
a thick mass of moving ice

7. Glaciar Perito Moreno, in Santa Cruz province, Argentina
Glaciar Perito Moreno, in Santa Cruz province, Argentina. It hasn’t happened since 1988 and it is said to be one of the most extraordinary natural events in the world.
- Roberto Cerrudo

8. Trans Labrador Highway

9. Snow to firn to glacial ice

12. How do glaciers erode the surface?
Plucking –freeze/thaw process lifts particles into ice
Striations- parallel scratches made from rocks in ice scraping against bedrock

13. Kelly’s Island Glacial grooves

16. Glacial polish

17. TYPES OF GLACIERS
Alpine (Valley)Glaciers – glaciers that form at high elevation in mountain valleys
Ice sheets or Continental Glaciers form in polar regions such as Greenland and Antarctica.

19. Cirque
A bowl-shaped depression located where a glacier begins to form

22. Horn A tall, pointed rock peak left at the top of a mountain
Kinnerly Peak - Glacier National Park
A tall, pointed rock peak left at the top of a mountain

23. The most famous horn in the Alps… The Matterhorn
Located on the boundary between Switzerland and Italy, the Matterhorn’s summit is 1500 feet above sea level.

24. Arete – spines or ridges of rock that separate glacial valleys

25. U-shaped Valley - Yosemite National Park

26. V-shaped valleys become U-shaped valleys as glaciers move through them…
Step 2
Step 1
A typical river valley
Over time, running water cuts a deeper V-shape.
Step 3
Glacier fills valley, widening and straightening the channel
Step 4
Glaciers melt leaving a U-shaped valley

27. VALLEY GLACIER

28. Glaciers pick up lots of sediment as they advance over the land.

29. TYPES OF GLACIAL DRIFT (Sediments)
TILL- unsorted; deposited by ice
STRATIFIED DRIFT- layered; deposited by meltwater streams
OUTWASH- sorted sand; deposited by meltwater

30. till
outwash

31. Erratics Boulders carried great distance by the glacier
Don’t match surrounding rock
“strange rock”

33. Erratics along Lake Michigan Shoreline

35. TYPES OF GLACIERS
Alpine (Valley)Glaciers – glaciers that form at high elevation in mountain valleys
Ice sheets or Continental Glaciers form in polar regions such as Greenland and Antarctica.

36. MORAINES Deposited along edge of glacier during melting Ridges of till
Terminal- very end of glacier
Lateral- side of glacier
Recessional- progresses behind terminal

37. MORAINES
MADE OF TILL

38. terminal moraine – unsorted sediments deposited at the edge of the melting glacier

40. Ground Moraine- flat till deposits between recessional moraines

41. Moraine Deposits = unsorted sediments
Moraines are made of unsorted sediments. Only mass movements and glaciers deposit unsorted sediments.
Since there are no large hills or mountains in Michigan for this sediment to fall down, it must have been deposited by the glaciers.

43. Drumlins
Hills of sediment deposited by the glacier- till

44. Boyne, Nubs Nob, Irish Hills are drumlins in MI

45. MI Drumlins

46. KAMES Cone shaped deposits Deposited at end of meltwater streams
Stratified drift

47. Mt. Holly is a kame

48. ESKERS Meandering ridges of stratified drift
Deposited by meltwater streams
Mined for gravel

49. Mt. Brighton
Mason esker

50. Kettle Lakes
Made from ice blocks
Deep inland lakes
rocky

51. Kettle Lakes
Kettle lakes form when blocks of ice break off the front edge of a glacier, become buried by sediment. The ice melts leaving a hole which fills with water creating a lake.

52. Outwash plain From melt water (lake) in front of ice Flat; sandy
Contains outwash and often kettle lakes

53. Pleistocene Epoch “Ice Age” 2my- present

54. 1.5 mya

56. mastodon

57. Mammoth
Bigger than mastodon
Curvy tusk

58. When the climate cooled…
Ice advanced over the land, moving southward from Canada over the Great Lakes Region.

60. Each of the Great Lakes began as a river.
Image from Earth Science, Tarbuck and Lutgens, 2003

61. As the climate cooled… The rivers froze.
Glaciers moved through the river valley – widening and deepening them to form today’s lake bottoms.

62. Why do scientists believe that glaciers once covered Michigan?

63. Moraine Deposits =unsorted sediments
What can deposit unsorted sediment?
Mass movement?
ice

64. Moraine Deposits have the same shape as the Great Lakes.
Michigan moraines run parallel to the shoreline.
The same process that formed the moraines formed the Great Lakes.

65. 3 ice lobes

66. When the climate began to warm, the glaciers began to melt and retreat.

67. The Glacial History of Michigan
The depth of the lake is determined by the thickness of the ice at the time of glaciation. The farther north the lobe of ice, the thicker it was.
Consequently, the lakes get more shallow in the southern Great Lakes region.
LAKE: GREATEST DEPTH:
Superior = 1,333 ft.
Michigan = ft.
Huron = ft.
Ontario = ft.
Erie = ft.

68. The fresh water from the melting glaciers filled in the deep U-shaped valleys that they had carved and turned them into the lakes we have today.

69. What other evidence do we have that glaciers once covered our state?
Depositional features such as drumlins and kettle lakes.
Kalkaska, Michigan

70. Isostatic (crustal) rebound land is rebounding up from weight of glacier about 53 cm/ century

71. Pictured Rocks

72. Kettle Lakes

73. Why do scientists believe that glaciers once covered Michigan?
Michigan is covered with till
The moraine deposits follow the outline of Great Lakes
Erratics
Striations
Isostatic rebound

74. What glacier evidence do we see in Grosse Pointe?
Erratics
Old beach ridges
Ridge road
Mack avenue
Till

76. Resources http://cse.cosm.sc.edu/erth_sci/Erosion/plucking.jpg