1. EARTH SCIENCE CHAPTER 15
GLACIERS

2. GLACIERS Chapter 15 GLACIERS I. What is a Glacier? Types of Glaciers
Mass of moving ice responsible for the most powerful agents of erosion 
Types of Glaciers
  Valley (alpine)
Continental (Greenland, Antarctica)

3. TYPES OF GLACIERS B. Valley glaciers (Alpine glaciers)
Long, slow moving stream of ice originating in the mountains.
C.  Ice sheets (Continental Glaciers)
Originating at the poles and expanding in all directions
Larger than valley or alpine glaciers.
FACT: ANTARCTICA HAS THE LARGEST CONTINENTAL ICE SHEET IN THE WORLD, 1 AND A HALF TIMES THE SIZE OF THE U.S. AND IN SOME PLACES 4,000 METERS DEEP
FACT: IF GREENLAND AND ANTARCTICA ICE SHEETS WHERE TO MELT THE SEA LEVEL WOULD RISE TO 60 METERS!

4. SNOW LINE Topic 3 The Snow line A. Definition
Where permanent snow occurs. More is produced than melts
B.   Snowline versus latitude
Lower at greater latitudes

12. BIRTH Topic 4 Birth of a Glacier A. Process
1. Firn (see Fig 11-4 on p. 174)
Recrystalization of snow into rough grains
2. Snow to Firn to Glacial Ice

19. ALPINE GLACIERS Topic 5 Where Valley Glaciers Occur (Alpine Glaciers)
  A.  Locations
Where mountains have elevations above snow line.

24. CONTINENTAL GLACIERS
Topic 6 Where Ice Sheets (Continental Glaciers) Occur
A.  Location
Where snow line is close to sea level
B.   Ice caps
Small ones (Iceland and Islands in Arctic Ocean)
C.   Continental glaciers
Antarctic glacier (5 km thick and 1.5 m below sea level)
Greenland
D.   Nunnataks
Mountain peaks that project through ice

28. MOVEMENT II. Glacier Movement Topic 7 How Glaciers Move
  A.   Process of movement
1. Weight pulls ice down
2. Melting aids lubrication
B.   Speed
  1.  Movement
From a few cm to 3000 cm /day
Faster in the middle.

29. CREVASSES

31. HOW FAR? Topic 8 How Far Glaciers Move
A.  Ice fronts - Where they end (can be below snow line)
  1.  Factors determining
Where ice melts as fast as it moves

32. CALVING B. Calving 1. Process 2. Icebergs 3. Ice shelves
When glaciers hit sea, blocks break off
  2.    Icebergs
What you get
  3.    Ice shelves
Occur over water where ice hasn’t broken off yet

39. TRANSPORT Topic 9 Glaciers Transport Loose Rock
  A.   Range of particle size
Fine powder to giant boulders 

40. MORAINES B. Moraines - deposited particles once glacier recedes
1.  Ground moraines - in glacier before deposited
     Lateral moraines - deposited on sides of glaciers
  3.   Medial moraines -deposited on the sides of two converging glaciers, resulting between the two
  4.   End moraines - deposited at the ice front

45. EROSION Topic 10 Glaciers Leave Their Mark
  A.   Description and formation
  1.   Striations - long parallel scratches
  2.   Roches moutonnees - sheep rocks
  3.   Cirque - semicircular basins at head of valley
  4.   Arête - knife edge ridge between cirques
  5.   Horns - result of 3 or more cirque producing a pyramid shaped peak

46. STRIATIONS

48. HORN

50. CIRQUE

52. ARETE

55. GLACIAL VALLEY Topic 11 Recognizing Glacial Valleys
A. Glacial troughs versus river valleys
1. U shaped vs. V shaped
B. Hanging troughs and hanging trough waterfalls
SMALL ABANDONED GLACIAL VALLEY SUSPENDED ON A MOUNTAIN ABOVE THE MAIN GLACIAL VALLEY.
WHAT NATURAL FEATURE DO YOU THINK WILL APPEAR WHEN A STREAM FLOWS FROM A HANGING VALLEY TO THE MAIN GLACIAL VALLEY?

60. Topic 12 What Continental Glaciers Do
A. Polished mountain tops versus sharpened ones

62. DEPOSITION III. Deposits By Glaciers Topic 13 Deposition Occurs
Drift - all deposits of glaciers
1. Till - unsorted and unstratified (inside glacier)
2. Outwash - sorted and stratified (left in front of glacier)

63. TILL

67. OUTWASH PLAIN

69. OUTWASH PLAIN

70. DEPOSITION Topic 14 Glaciers Leave Moraines
A. Recessional and terminal moraines - what’s left behind by a glacier and the deposit left by farthest advance.
B. Erratics - large transported boulders

71. MORAINES

72. MORAINE

74. ERRATIC

75. ERRATICS

76. DRUMLINS Topic 15 Drumlins
A. Formation and description - long smooth canoe - shaped hills made of till produced when advancing glaciers have run over earlier glacial moraines
B. Examples - Southeastern Wisconsin, South of Lake Ontario, Boston, Massachusetts

77. DRUMLINS

78. DRUMLINS

79. Topic 16 Outwash Plains and Eskers
A. Outwash plains
Formation and description - broad flat areas in front of glaciers (usually prairies or farmland today)
B. Eskers
Formation and description - long winding ridges where material was deposited in tunnels within glacier
Examples - Maine and New York

80. OUTWASH PLAIN

82. ESKER

84. ESKER

85. Topic 17 Kames, Kettles, and Deltas
A. Kames
1. Formation and description
Small cone shaped hills of sand and gravel from streams on top of glaciers
B. Kettles
Circular hollows on terminal moraines and outwash plains formed from large blocks of ice settling out and melting
C. Deltas
When glacial streams empty into lakes

86. KAMES

87. OUTWASH PLAIN

89. CIRQUE LAKES Topic 18 Lakes Made by Glaciers A. Cirque lakes
1. Formation
When water fills the rock-floored cirque left by a glacier
2. Examples
Lake Louise, British Columbia

90. CIRQUE LAKE

91. KETTLE LAKES B. Kettle lakes 1. Formation 2. Examples
Water from ice melt left behind in kettles
2. Examples
Zillions of them in Minnesota and Wisconsin, not to mention the Great Lakes

94. C. Moraine – dammed lakes
1. Formation
River valleys blocked by glacial moraines
2. Example
Devil’s Lake, Wisconsin

100. ICE AGE IV. The Ice Age Topic 19 How It Happened
(NOTE OBJECTIVES A – C ON PAGE 183)
Topic 19 How It Happened
A. When it occurred - 1,000,000 years ago, we’re still in it!
B. Extent - Intersection of Ohio and Mississippi rivers and as far east as NY
C. North America’s 3 major centers
1. Labrador center - east
2. Keewatin - central
3. Cordilleran - west
D. Cyclical - Advanced and receded 4x’s; 11,000 years ago was last advance

102. Topic 20 Ice Age Evidence A. Limits tied to terminal moraines
Terminal moraines found from New Jersey through Pennsylvania, to Indiana and beyond.
Outwash plains are found beyond.

104. Topic 21 Causes of Glacial Climates
A. Four facts to consider
1. I million years ago, Ice Age began, including 4 major advances of the ice sheets.
2. Warm interglacial periods came between.
3. Other ice ages have occurred in the past 600 million years.
4. In last age, glaciers advanced and receded in North and South hemispheres at the same time.

105. B. Possible causes 1. Energy from sun changes.
2. Volcanic activity and dust in atmosphere.
3. During mountain building more land was above snow line. (More land under ice, might change the climate)
4. Continents in older formations may have prevented hot and cold water currents from mixing.
5. Changes in earth’s tilt.