Page 38 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

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concepts
key leARNING
Essentials of Geography
After reading the chapter, you should be able to:
• Define geography in general and physical geography in particular.
• Discuss human activities and human population growth as they relate to
geographic science, and summarize the scientific process.
• Describe systems analysis, open and closed systems, and feedback
information, and relate these concepts to earth systems.
• Explain earth’s reference grid: latitude and longitude and latitudinal
geographic zones and time.
• Define cartography and mapping basics: map scale and map projections.
• Describe modern geoscience techniques—the Global Positioning System (GPS), remote sensing, and geographic information systems (GIS)—and explain how these tools are used in geographic analysis.
A snow avalanche roars down mountain slopes at Rogers Pass in Glacier National Park in the Selkirk Mountains, British Columbia. Between 1885 and 1950, nearly one hundred
lives were lost in the pass due to avalanches burying the Canadian Pacific railway line. In 1910, 58 railway workers died in Rogers Pass in Canada’s largest avalanche incident. This tragedy, previous deaths, and difficulties Canadian Pacific was having with the steep grade led to digging tun- nels through the mountains for the railway (the Connaught Tunnel opened in 1916 and the Mount Macdonald Tunnel opened in 1988). When the Trans-Canada Highway was built through the pass from 1956-1962, static defences against avalanches were constructed, such as earth mounds, dykes and snowsheds. In addition, snow and avalanche observa- tions began and the world’s largest mobile avalanche control program using live artillery was established between Parks Canada and the Canadian Armed Forces in order to keep the Trans-Canada Highway and Canadian Pacific Railway corridor open and safe during winter. Potentially unstable snowpacks that threaten the transportation corridor are disloged before they reach critical status by using a 105 mm C-3 Howitzer. [J. Bradford White/Alpenstock.]