Topographic maps, two-dimensional depictions of terrain, are invaluable tools for outdoors enthusiasts--and beautiful pieces of art.
A topographic map’s scale fraction or ratio refers to any measurement unit. On a map with a scale of 1:12,000, one inch on the map equals 12,000 inches in the actual depicted terrain, just as one map foot, one map centimeter, and so on would equal 12,000 feet, centimeters, and so forth on the ground.
Contour lines are the foundation of the topographic map. Along the length of any given line, the elevation remains the same. Some contour lines will be labeled (in feet or meters) as references. Closed contours represent summits, and ones with hatch marks represent depressions.
The map will provide a contour interval, which refers to the vertical difference between two adjoining lines. A smaller contour interval--one of 500 feet, say, instead of 2,000--will show greater detail.
Maps and Geology
You can make an educated guess about an area’s underlying geology simply from the contours of a topographic map. For example, a highland with a very steep scarp on one edge and a gradual slope on the other might suggest terrain dominated by faulting.
Topographic maps, when used with a compass, are essential for backpackers, hunters, and others navigating in roadless wilderness.
- "Interpretation of Topographic Maps"; Victor C. Miller, Mary E. Westerback; 1989.