You will use the 1:50,000 scale Columbia Ice Field topographic map sheet to answ

Question

You will use the 1:50,000 scale Columbia Ice Field topographic map sheet to answer the questions in this section. Copies of these are in the tutorial room. A copy of an aerial photograph from 1966 is attached to the tutorial. A digital version of the tutorial will be available on the course Blackboard site (the air photo may be more legible in the online version). You will need a pencil and ruler Glaciers and Moraines on Topographic Maps: Most topographic maps use light blue shading for glacier ice. A random pattern of brown dots of different sizes marks fresh moraines, and sometimes other areas of exposed loose rock. Glacier ice covered with rocky debris is white-blue with the brown dot pattern superimposed. Check the Columbia Ice Field topographic map to ensure that you can recognize each of these surface types. The legend is on the back of the map While you are looking at the map sheet, take note of the Athabasca and Saskatchewan Glaciers, and the Parkway and Sunwapta Lake Ice Fields. The latter is a meltwater lake presently slightly past the snout of the Athabasca Glacier 1) What is the position of Sunwapta Lake (latitude and longitude in degrees, minutes)? (1 pt) The equilibrium line altitude (ELA) is a theoretical dividing line between a glacier's accumulation zone and ablation zone. For many glaciers, the highest elevation reached by lateral moraines is approximately the glacier's ELA 2) How high (what elevation) do lateral moraines reach on the Athabasca Glacier? (1 pt) 3) On the Saskatchewan Glacier? (1 pt) Another indication of ELA for a valley glacier is that the surface profile of the glacier, measuredperpendicular to the valley is concave above the ELA versus conver or flat below the ELA. Looking at the Athabasca Glacier, can you see this transition? To see it, you need to study the shape of the contour lines as they cross the glacier Imagine yourself walking across the glacier from one valley wall to the other. Are you going down or up as you approach the centre of the glacier? Expect a gradual, not dramatic, difference between concave and convex glacier profiles 4) At what elevation does the transition from convex to concave occur on the Athabasca? (It's OK to give a 100 m wide range as an answer) (1 pt) 5) There is a very fast method of approximating the modern ELA that only works at certain times of year (described in class). What is it? (1 pt)

Explanation / Answer

1. Coordinates of Sunwapta lake as determined from the topographic map is:

52 degree 12 minutes 54.7 seconds North

117 degree 14 minute 6 seconds west

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