Topographic maps provide information on the elevation, relief, and slope of the ground surface. A topographic map uses contour lines to show you the surface features of an area as if you were looking down on them from above. Each contour line on the map connects points of equal elevation. Closely spaced contour lines show steep slopes. Widely spaced contour lines show gentle slopes or flat areas.
▴ Contour Lines
In the topographic map of Crater Lake National Park, closely spaced contour lines surrounding the lake represent steep slopes along the lake's perimeter. For this map, the contour interval, or the change in elevation from one contour line to the next, is 200 feet.
▴ Crater Lake
Located in southwestern Oregon, Crater Lake has an average surface elevation of 6176 feet (1882 meters) above sea level. At the west end of the lake lies Wizard Island, which rises to 764 feet (233 meters) above the water.