1. Glacial Modification of Terrain
Chapter 19
Glacial Modification of Terrain

2. Glacial Modification of Terrain
Glaciations Past and Present
Types of Glaciers
How Glaciers Form
Continental Ice Sheets
Mountain Glaciers
The Periglacial Environment

3. Pleistocene Glaciation
At maximum covered 1/3 of total land surface
The Laurentide ice was the most extensive Pleistocene ice mass

4. Extent of Glacial Ice Today
10% of land surface

6. Indirect Effects of Pleistocene Glaciation
Erosion & deopostion from meltwater
Sea-level change: cooling lowered – warming raised
Isostacy or rebound i.e. crustal depression
Increased rain developments: more moisture available – more lakes

7. Types of Glaciers Continental Ice Sheets Mountain Glaciers Confined
Highland Icefields
Alpine Glaciers
Confined
Unconfined

8. Continental Ice Sheet - Greenland
Completely inundate all terrain
Spread outward in all directions
Because of size, may influence climate
Unconfined

9. Outlet Glacier Along margin of sheet
Continental
Along margin of sheet
Between hills or mountains to the sea

10. Antarctica – Sheet vs. Shelf
Continental - Unconfined

11. Larsen Ice Shelf - Calving

12. Mountain - Highland Icefields

13. Confined Glaciers
Piedmont
Cirque
Valley

14. Alpine Glaciers
Valley
Cirque

15. How Glaciers Form Changing Snow to Ice Glacial Movement
Erosion by Glaciers
Transportation by Glaciers
Deposition
Glaciers
Meltwater

16. How Glaciers Form
Three parameters important to ice sheet waxing and waning:
Changes in the eccentricity of the Earth's orbit
Changes in the tilt of the Earth's axis
The precession of the equinoxes
In combination, these factors influence the amount and distribution of solar radiation reaching the Earth.
Changes vary with both latitude and season.
Changes in the amount of solar radiation drive the growth and melting of major ice sheets.

17. Snow to Ice Snow crystallizes directly from water vapor
It is NOT frozen water
It is 1/10 as dense as water
Compressed to granular form 1/5
Then to ½ density
Called Neve or Firn
With time, to 9/10
Blue glacial ice

18. Accumulation and Ablation
Figure 19-9

19. Glacial Movement Glacial ice deforms rather than breaks
Partial melting allows it to slide

20. Glacial Till

21. Glacial Erratic

22. Continental Ice Sheets
Development and Flow
Erosion by Ice Sheets
Deposition by Ice Sheets
Kames and Kettles
Moraines
Drumlins
Glaciofluvial features
Outwash Plains, Eskers, and Kames

23. Ice Sheet Deposition

24. Kames and Kettles
Kame
Kettle Formation

25. Growth of a Terminal Moraine

26. Mountain Glaciers Development and Flow Erosion by Mountain Glaciers
Mountain Landforms
Cirques, Arretes, Horns
Tarns
Valley Landforms
Glacial Trough
Paternoster Lakes
Hanging Valleys
Deposition by Mountain Glaciers

27. Mt. Rainier, WA

28. Cirques
Figures and 19-27

29. Mountain Landform Development
Figure 19-28

30. Glacial Trough

31. Glaciated Valleys

32. Medial Moraines
Figure 19-38

33. Moraines in Mountains

34. Outwash Deposition
Ice prevented outwash deposition in Wellfleet Harbor

35. Cape Cod Glaciation

36. Outwash Plain Greenland Glacial Boulder Eastham, MA

37. Glacial Erosion Cape Cod
present pattern of erosion
6,000 years ago
Before wave erosion
Present pattern of
erosion

38. Cape Cod Geology

39. Aerial Greenland Ice Cap