Laboratory Manual for Introductory Geology 4e

EXERCISE 15.8
Measuring the Retreat of the Athabasca Glacier
Name:
Course:
Section:
Date:
You have been hired as a consultant to advise the Alberta tourist bureau and Parks Canada on how much longer the
Athabasca Glacier will be viable as a tourist attraction. Note on the map in Figure 15.18b that the glacier’s terminus does
not follow a straight line, but flows around the contours of the landscape. So, to estimate the past rate of retreat, you need
to follow a straight line from the current terminus (the farthest-extending point of the glacier) to the location where the
1843–1844 terminus intersects the Old Banff–Jasper Highway (the red dashed line on the figure).
(a) Measure the amount of retreat from 1843 to 1999 along the line you drew:
(b) Determine the average rate of retreat during that period:
Average rate of retreat 5 m 4 156 years 5 m/yr
You note that the spacing of the dated terminus positions in Figure 15.18b suggests that the rate of retreat has not always
been consistent: at some times, the glacier appears to have retreated more rapidly than at others.
(c) Compute the rates of retreat during different shorter time periods:
(i) from 1843 to 1906:
m/yr
(ii) from 1906 to 1999:
m/yr
m
Head of
Athabasca Glacier
2010 terminus
1938 terminus
?
What Do You Think The photo above is a recent view of
the Athabasca Glacier. It is now approximately 6.2 km from the glacier’s
terminus to its source. You have measured rates of past retreat over three
different time periods and can now use those rates to estimate how much
longer the glacier will exist. The number of years it would take for the glacier
to melt completely based on your estimate above from
●●
question (b) is years.
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question (c.i) is years.
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question (c.ii) is years.
406 CHAPTER 15 GLACIAL LANDSCAPES