1. Glaciation in Canada

7. Introduction
Weight of the ice caused parts of Canada to sink > 300m
Power of these giants shaped Canada’s landscape as we know it today
Stripped the Canadian shield of topsoil
Plucked enormous boulders and transported them 1000snds of km
Dredged out new lake bottoms
Rerouted rivers
Gouged, scraped and polished exposed rock
Created rolling plains of deep, fertile soil, ridges and 1000snds of lakes

8. Glaciation
Ice sheets have covered much of Canada several times over the last 2 million years
15,000 years ago Canada and much of North America was covered in ice up to 4km thick!

10. Why Does Glaciation Happen?
During the last Ice Age, glaciers advanced and retreated at least 4 times
Why? No certain answers only theories
Change in tilt of earth’s axis (41,000 yrs)
Change of earth’s orbit (100,000 yrs)
Change in heat output from the sun (26,000 yrs)

11. How Does a Glacier Form? Begins when the earth’s climate cools
Winter snow fall greater
then summer melt
1000snds of years snow accumulates (zone of accumulation)
Becomes hundreds to
thousands of m thick

12. Tremendous weight of snow turns bottom layer to ice
Solid ice acting like a very thick liquid begins to flow outward from zone of accumulation

13. Alpine Glaciers
Alpine Glaciers, glaciers move down mountains under force of gravity

15. Amounts to a few cm per day
Sharpen the upper portions of mountains (fig.2-20)
As they move down valleys scrape away valley walls creating U-shaped valleys (fig. 2-20)

18. Piedmont Glacier

22. Alpine Glacial Features

25. Continental Glaciers Occupy greater areas of land
Last Continental Glacier covered 8 million square kilometers of N.A. and in some areas was up to 4 km thick

26. Continental Glacier Today

29. Continental glaciers give the landscape a smoother appearance by eroding high points and filling in lower areas with eroded material

30. Glaciation in Canada
Glaciers move like a conveyor belt. The top moves faster than the bottom – resulting in the enormous amount of debris called till being picked up and moved along the top and deposited at the front / side of a glacier.
Depositional Features
Erosional Features

31. Sub-glacial Features

32. Striations

33. Striations?

34. Drumlin

35. Esker

36. Erratics on Esker

38. Kettle Lakes