2. Glaciers
Glaciers are a part of both the hydrologic cycle and rock cycle
Glacier – a thick mass of ice that forms over land from the compaction and recrystallization of snow and shows evidence of past or present flow

3. Glaciers Types of glaciers
Valley, or alpine glaciers – form in mountainous areas

4. Glaciers Types of glaciers Ice sheets or continental glaciers
Large scale
e.g., Over Greenland and Antarctica
Other types
Ice caps and piedmont glaciers

5. Glacier Movement Types of glacial movements Zone of fracture
Plastic flow
Slipping along the ground
Zone of fracture
Uppermost 50 meters
Crevasses form in brittle ice

6. Crevasses

7. Glacier Movement Zone of accumulation – the area where a glacier forms
Zone of wastage – the area where there is a net loss due to melting

8. Glacial Erosion Glaciers erode by Plucking – lifting of rock blocks
Abrasion
Rock flour (pulverized rock)
Striations (grooves in the bedrock)

9. Glacial Erosion Landforms created by glacial erosion Glacial trough
Hanging valley
Cirque
Arête
Horn
Fiord

10. Erosional Landforms Created by Alpine Glaciers

11. The Matterhorn in the Swiss Alps

12. Glacial Deposits Glacial drift All sediments of glacial origin
Types of glacial drift
Till – material that is deposited directly by ice
Stratified drift – sediment deposited by meltwater

13. Glacial Deposits Depositional features
Moraines – layers or ridges of till
Types of moraines
Lateral
Medial
End
Ground

14. End Moraines of the Great Lakes Region

15. Glacial Deposits Depositional features Outwash plain or valley train
Kettles
Drumlins
Eskers
Kames

16. Glacial Depositional Features

17. Ice Age Glaciers Glaciers of the past Ice Age
Began 2 to 3 million years ago
Division of geological time is called the Pleistocene epoch
Ice covered 30 percent of Earth’s land area

18. Extent of Ice Age Glaciation

19. Ice Age Glaciers Effects of Ice Age glaciers
Migration of animals and plants
Rebounding upward of the crust
Worldwide change in sea level
Climatic changes

20. Ice Age Sea Level

21. Causes of Ice Ages Successful theory must account for
Cooling of Earth, as well as
Short-term climatic changes
Proposed possible causes
Plate tectonics
Continents were arranged differently
Changes in oceanic circulation

22. Late Paleozoic Ice Age

23. Causes of Ice Ages Variations in Earth’s orbit Milankovitch hypothesis
Shape (eccentricity) of Earth’s orbit varies
Angle of Earth’s axis (obliquity) changes
Axis wobbles (precession)
Changes in climate over the past several hundred thousand years are closely associated with variations in Earth’s orbit

24. Orbital Variations

25. Deserts Any situation with a water deficiency
Distribution and causes of dry lands
Global distribution of air pressure and winds
Deep interiors of landmasses
Presence of high mountains