1. Glaciers

2. Glaciers:
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. Types of glaciers
Valley/mountain/alpine glaciers – form in mountainous areas
Ice sheets or continental glaciers
Large scale
e.g., Over Greenland and Antarctica
Ice Caps: Small Ice sheets

4. Currently ice sheets cover Greenland and Antarctica

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

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

7. Accumulation and Wastage
Figure 6.7

8. Glacial Erosion Plucking – Gouging out and lifting of chunks of rocks
Abrasion
Striations (scratches and grooves in the bedrock)

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

10. Erosional landforms created by alpine glaciers

11. The Matterhorn in the Swiss Alps

12. Glacial deposits Glacial drift
Till – material that is deposited directly by ice
Stratified drift – sediment deposited by water melting off surface of glacier

13. Glacial till is typically unstratified and unsorted
Figure 6.13

14. Close-up view of the boulder in the previous slide

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

16. Glacial deposits Depositional features Outwash plain or valley train
Kettles
Drumlins
Eskers
Kames

17. Glacial depositional features

18. Kettle lakes

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

20. Maximum extent of ice during the Ice Age
Figure 6.22

21. Indirect effects of Ice Age glaciers
Migration of animals and plants
Rebounding of the crust
Drop in sea level
Climatic changes

22. Causes of glaciation Variations in Earth’s orbit
Shape of Earth’s orbit varies
Angle of Earth’s axis changes
Axis wobbles