11) Backcountry skiiers sometimes use the Columbia Glacier to exit the centre of

Question

11) Backcountry skiiers sometimes use the Columbia Glacier to exit the centre of the ice fields. They might start at The Trench' (a feature of the ice field marked on the map), and then work down toward the snout. A field of crevasses occurs along this route (unfortunately for skiiers). This topographic map does not show crevasses. However, based on your knowledge of glaciers, where do you think crevasses would most likely occur? (give the likely position of crevasses, in terms of the number of km from the end of the glacie) (2 pts) Interpreting Aerial Photographs Look at the aerial photograph on the last page ofthis utorial, which shows the Athabasca Glacier and the NW corner of the Columbia Ice Field. This is a copy of a black and white air photo taken in 1966. The film used was sensitive to visible light, meaning it 'sees' as a human eye does, unlike some photos which record longer wavelength near-infrared light. 12) On the airphoto, there are shadows cast by mountains. Given the positions of the shadows, from which side of the photo was the sun shining when the photo was taken? (Choose between bottom, top left, or right) If you are not sure by looking at the photo alone, it might be helpful to study the topographic map to understand where peaks lie. (1 pt) 13) Compare Airphoto to the full size topographic map. Is the air photo oriented so the top of the photo points straight north? (yes or no) If you answered no, then which direction is it oriented? (1 pt) Note: Mamy air photos have arbitrary orientations, meaning north is not always at the top of the photo. The flight lines (path followed by the plane as it takes the photos) are chosen to simplify and minimize flying, not for convenient interpretation. For the following four questions use lecture notes and discussions. 14) A major sheet of glacial outwash gravel (useful material for road construction, etc.) occurs in the Halifax region. Is this outwash on the East (Dartmouth side) or West (Halifax side) of the Harbour? (1 pt) 15) Judging by the general shape and orientation of drumlins in the Halifax region, ice that flowed here during the last ice age (15,000 years ago) was moving in the following direction: (1 pt) a) southwest to northeast; b) northwest to southeast; e) north to south 16) If looking for well-sorted gravel to use for road construction, would you seek glacial landforms that look like a) a sinuous winding ridge; or b) a big U, such as is formed at the snout of a flowing glacier? (1 pt) 17) True or False: If you fall into a crevasse, you probably won't stop until you hit bedrock at the base of the glacier. (2 pts)

Explanation / Answer

11. Yes, crevasses will occur. Crevasses are cracks, often too deep, in glaciers and ice sheets. Since there is an icesheet and differential shear stress in the area shown in the map.

12. The sun shines from the Eastern portion of the map i.e. the right side of the map.

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