1. GLACIERS

2. Glaciers: Erosion and Deposition
Photo source: Environment Canada (2005) Retrieved on: Jan From: glaciers/glaciers_edu_e.cfm
Glaciers: Erosion and Deposition

3. Glaciers
They occur when snowfall exceeds melting in a particular region
Year after year of snowfall builds up
The pressure condenses the lower layers into hard packed ice
Definition: a large mass of flowing, perennial ice
Huge erosive potential, more than wind and perhaps water

4. glaciers
Large glaciers are generally located in the far north and south and in the mountains
There are glaciers in Africa, Europe, Asia, North America and South America
Glaciers are studied for scientific research
Glaciers can be tourist attractions (especially in Canada)
Image source: glacier bus (2005) Retrieved on Jan From:
Trekkers (2005) Retrieved on Jan From:

5. Mountain Glaciers
Image source: Retrieved on Jan from:

7. Alpine/Mountain Glaciers and Features

8. Cirque and Arete - Erosion

9. Cirque

10. Horn

11. Landscape formation
Through various erosive properties the ice is able to erode even the strongest rock
Through freeze-thaw cycles
By grinding
By sheer weight
Source: glaciers/glaciers.htm

12. Arete-erosion

13. Matterhorn: horn-erosion

14. Alpine Glacial features
As ice accumulates it begins to flow, the glacier picks up material and when it melts the sediment is deposited
These deposits of glacial material are called moraines
This is one way in which glaciers modify the landscape
Image source:
This alpine glacier is on Baffin Island

15. Glacial Erosion Features
Arete
Cirque
Horn

16. Arete

17. Alpine: moraine-deposition

18. lateral moraines
Lateral moraines form along the sides of the glacier as it carves out the valley

19. Terminal moraine
Terminal moraines form a ridge of material at the bottom end of the glacier
Source: Retrieved on Jan From:

20. Snout

21. Snout-Deposition

22. Glacial valley The valley starts with a V profile
Glacial action erodes the sides of the valley
The valley profile is transformed to a U profile
Can result in hanging valleys/waterfalls
Can result in knife edge ridges and peaks called arêtes and horns
This will be easier demonstrated on the blackboard.
Image source: Retrieved on Jan From:

23. Horn: steep peak as a result of glacial action (example: the Matter horn)
Hanging valley: smaller tributary valley entering the main glacial U shaped valley
Image source: Waterfall Retrieved on Jan from:
Matter horn Retrieved on Jan From:

24. Hanging Valley, Lateral Moraine

25. Glacial valley & Fjord formation
Source:
Glacial valleys: on land
Fjords: On coast and flooded with sea water

26. Fiord in British Columbia

27. Fiord-erosion

28. Gros Morne Fjords, Newfoundland
Image source: Retrieved on Jan From: : SIT/sit_pages/13054.html
Gros Morne Fjords, Newfoundland

29. Receding Both continental and alpine glaciers are receding
Melt is exceeding accumulation
What does this say about the earths climate?
Source:

30. Zone of accumulation Zone of ablation
Area where glaciers are fed through the constant or seasonal build-up of snow mass
The weight of this accumulation combined with gravity and the fact that the bottom of the glacier is “floating” on water causes the glacier to move downhill
Zone of ablation
Area of melt at lower elevations
Leaves debris to accumulate at the end (terminal moraine)
Leaves debris at the side of the glacier (lateral moraine)

31. Glaciers Alpine glaciers Continental glaciers
Form on the peaks of individual mountains
Wherever snow accumulates year after year without melting
Example: Athabasca glacier
Continental glaciers
Cover vast areas
Can be quite thick 3-10 km
Have covered all of Canada and part of the U.S.
These occur during ice ages
Currently: Antarctica and Greenland

32. Continental glaciers There are still continental glaciers
Canada and northern Europe have been covered by glaciers at least four times throughout history
These glaciers are receding (melting)

33. Extent of Continental Glacial Coverage in Northern Hemisphere
Source: Retrieved on Jan From:

34. Evidence of glaciers-Deposition
Glacial erratic: boulder carried by glacier
Drumlin: elongated hill left by receding glacier (Peterborough area)
Source: Glacial erratic retrieved on Jan From: TomTits2000/sweden10.html
Drumlin field retrieved on Jan From:

35. aligned in direction of
Drumlins:
aligned in direction of
glacier advance.
Source: Retrieved on Jan from:

36. Drumlin-deposition

37. Drumlin

39. Eskers-Continental Glaciers
Formed when a river forms within the glacier
This river deposits debris like any other river
This debris is left once the glacier recedes
An Esker is a kind of odd-shaped small hill which is found in territory where a large glacier has melted.
Eskers are formed when melting ice creates rivers within the body of a large glacier. The melt water carves a channel within the glacier and deposits sand or gravel along the channel as any stream or river would do.
When the glacier melts completely, the sand within these channels can create a long, snake-shaped curving hill. Some of these hills in New England resemble a winding railroad embankment or fortification -- about 20 feet high, thirty or forty feet wide and 100 yards or more long. Some eskers are much larger.
Source: Eskers (2005) Retrieved on Jan From: mmcconeghy.com/students/ supglaciersinri.html

40. Esker

41. Glacial Moraine

42. ERATICS
-TRANSPORTATION

43. Isostatic rebound
is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period
- Time to get out the ice cube (glacier) saran wrap spread over a bowl (earth’s crust) leave the ice cube on the saran wrap long enough that is sags somewhat. When you remove the ice cube the saran wrap will become taught once again.
Be sure to explain that this process takes millions of years and is still occurring today from the last ice age.
Demonstrate the buoyancy of icebergs using the same tools.

44. Iceberg buoyancy
Is effected by the amount of air trapped in the iceberg
The amount of salt in the water
Generally the iceberg floats with 7/8 below water (87.5%)

45. Icebergs
Image source: Retrieved on Jan From:

46. Icebergs A glacier that is producing icebergs is said to be calving
Check out the cover of your text book
Icebergs can be a threat to boats
Icebergs have 7/8 of their mass under the water line, hence the term “tip of the iceberg”
glaciers range from ice cube size to the size of PEI
Source: Retrieved on Jan18-05 from:

47. Alpine glaciers Form on the peaks of individual mountains
Are restricted to higher elevations
Create U shaped valleys out of V shaped valleys through erosion
Image source: Retrieved on: Jan From: