| Geoscience and Environment |
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Topography refers to elevations and topographic maps show elevations, usually by lines that connect points with the same elevation above sea level and additional surveyed spot heights as dots or triangles with numbers. The map shows a triangle at the peak of Mount Shasta with the number 14,162 representing the number of feet above sea level (about 4,330 meters). Just above the words Bolam Glacier the map shows a line broken by the number 10000. This line follows the 10,000 foot (3,058 meter) contour. The interval between contour lines is 80 feet (24.5 meters). Southeast of Lake Shastina the 10,800 foot and 11,600 foot contours are about 1,500 feet apart, thus the contour lines are 150 feet apart horizontally and 80 feet apart vertically. The slope is 80/150, making an average angle of 28 degrees from the horizontal.Glaciers can be inferred from the blank areas of the map. Ice conceals the surface of the mountain forcing gaps in contour lines. Every fifth contour line is shown, indicating accuracy to within plus or minus 200 feet (+/-200 feet or +/-60 meters). Source: Osterkamp, W.R. Magnitude and frequency of debis flows, and areas of hazard on Mount Shasta, northerm California. U.S. Geological Survey Professional Paper 1396-C,, 1986, Plate 1 (in pocket). |
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