Topography maps use contour lines to describe mountains, lowlands and waters.
At first glance a topographic map looks like a random assortment of lines, curvy shapes and pastel colors. Topographic maps use contour lines or level lines to represent an area’s three-dimensional surface features in a two-dimensional medium, such as paper. Mapmakers assign representative shapes or contours to particular types of landforms such as mountains and river valleys, and they place numbers adjacent to lines to indicate elevations. These lines run through and connect all areas of the same elevation. The maps depict landforms from a top-down perspective, so features appear to you as if you are viewing them from directly above.
1. Locate a number written next to or between two segments of a line on a topographical map. The lines are usually brown. This number represents elevation.
2. Interpret the elevation that the number represents by referring to the map’s key or legend. Determine if the number five, for example, represents five feet or five meters of elevation above sea level.
3. Follow or trace the line on the map. All areas along the line are at the same elevation.
4. Locate steep increases in elevation by noting how close level lines are to one another. The lines of a steep slope are close together. The lines on the map which are farthest apart represent the most gradual increase in elevation.
5. Locate an isolated hill on the map by looking for a series of concentric rings. Notice the difference in the elevation of the inner ring (the top of the hill) and the outer rings, which represent the descending slopes.