1. CHAPTER 5 HONORS EARTH SCIENCE
GLACIERS
CHAPTER 5
HONORS EARTH SCIENCE

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

3. Step 1: Snow accumulates.
How do glaciers form?
Step 1: Snow accumulates.
More snow falls during the winter than melts in the summer.

4. Trans Labrador Highway

5. Step 2: Snow changes to firn.
As snow accumulates, its weight compress the individual snowflakes to form firn.
FIRN

6. Firn

7. Step 3: Firn is compressed to form solid glacial ice.

8. http://www.asf.alaska.edu:2222/img/firn_diagram.gif http://207.239.98.44/IcelandI%20232.jpg

9. Step 4: The ice begins to move.
Plastic flow- weight of glacier moves out like pancake batter

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

11. 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

12. Glacier terms Zone of Ablation- melting
Zone of Accumulation- snow accumulates
Crevasse- cracks
Advance- more accumulation than melting
Retreat- more melting than accumulation

13. VALLEY GLACIER

14. 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

16. Glacial Striations Granite Island, Lake Superior MI Calumet, MI
N47°14’77’’ W88°26’82’’

17. Kelly’s Island Glacial grooves

20. TYPES OF GLACIERS
Alpine (Valley)Glaciers – glaciers that form at high elevation in mountain valleys
Ice sheets or Continental Glaciers.

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

24. 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

25. The most famous horn in the Alps… The Matterhorn
Located on the boundary between Switzerland and Italy, the Matterhorn’s summit is 4478 m above sea level.

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

27. U-shaped Valley - Yosemite National Park

28. 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

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

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

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

32. Erratics along Lake Michigan Shoreline

34. TYPES OF GLACIERS Alpine (Valley)Glaciers –
Ice sheets or Continental Glaciers form in polar regions such as Greenland and Antarctica.

36. MORAINES MADE OF TILL Deposited along edge of glacier during melting
MADE OF TILL
Deposited along edge of glacier during melting

37. MORAINES Terminal- very end of glacier Lateral- side of glacier
Recessional- progresses behind terminal

38. terminal moraine –

39. Ground Moraine- flat till deposits between recessional moraines

41. Kettle Lakes
Made from ice blocks

42. 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.

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

44. Drumlin Formation

45. ESKERS Winding ridges of stratified drift
Deposited by meltwater streams
Mined for gravel

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

48. What glacial landform are the arrows pointing to?

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

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

56. 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.

57. 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.

58. 3 ice lobes

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

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

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

62. 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.

63. 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.

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

65. Kettle Lakes

67. Mt. Holly

68. Boyne Mountain

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

71. Isostatic rebound
The land is rebounding once the weight of the glacier left
3 cm/year

72. Isostatic rebound Pictured Rocks

73. Glacial polish

74. 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
Glacial polish

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