1. Chapter 18 Glaciers & Glaciation

2. Glaciers
Mass of ice forming when more snow/ice is deposited in fall/winter than is melted in spring/summer

3. Glacial Ice

4. Types of Glaciers
Valley/Alpine Glaciers
Mountains
Migrate downslope

5. Types of Glaciers Ice Sheets/Continental Glaciers
Larger than valley glaciers
Move in all directions
2 Major Ice Sheets
(Greenland & Antarctica)

6. What if all the ice melted?
Antarctic ice sheet
80% of the world’s ice
2/3 of Earth’s fresh water
~ 1.5 times the area of the US
Sea level would rise ~70 meters

7. Sea level and Glacial Ice

8. The Glacial Budget
Figure 18.11

9. Glacial Deposits Glacial Drift – all sediments of glacial origin
Till – material deposited directly by ice
Stratified Drift – deposited by meltwater

10. Till usually Unstratified & Unsorted
Figure 18.19

11. Glacial Deposits Landforms made of till
Moraines – layers or ridges of till
Lateral
Recessional
Terminal or End

12. Lateral Moraine – Alpine Glaciers

13. Glacial Deposits
Figure 18.25

14. Moraines of Long Island

15. Glacial Deposits Outwash Plains Flat with mild slopes
Form from meltwater deposits
Occurs beyond moraine

16. Glaciers of the past Four major stages in North America
During peak ~ 30% of earth was covered
Nebraskan (ended ~ 1.6 mya)
Kansan (ended ~ 690,000 ya)
Illinoian (ended ~ 125,000 ya)
Wisconsinan (ended ~ 10,000 ya)

17. Maximum extent of ice during the Ice Age
Figure 18.27

18. Current Glacial Ice Covers ~ 10% of earth’s surface Antarctic ~ 85%
Greenland ~ 10%
Scattered ~ 5%

19. Current Glacial Coverage

20. Impacts of Glaciers Migration of animals & plants
Crustal rebounding of the crust
Changes in sea level
Climatic changes

21. Causes of Glaciation Plate Tectonics
Continents in different areas in the past
Changes in oceanic circulation

22. Shape of Earth’s orbit varies
Causes of Glaciation
Milankovitch Hypothesis
Shape of Earth’s orbit varies
Angle of Earth’s axis changes
Earth’s axis wobbles (precession)

23. Milankovitch Hypothesis

24. End of Chapter 18