Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which is usually mean sea level. Contours make it possible to show the height and shape of mountains, the depths of the ocean bottom, and the steepness of slopes.
What Are Contour Lines on a Topographic Map?
Contour lines are lines drawn on a map that connect points of equal elevation. In other words, every point on a contour line is at the same height above sea level.
Contour lines are a useful tool for visualizing landforms and relief, and for determining elevation changes between different points on a map.
In addition, contour lines can be used to estimate the size and shape of a landform, and to measure distances between points. Contour lines are typically spaced at regular intervals, such as every 10 feet or every 100 meters.
The spacing of contour lines varies depending on the scale of the map.
For example, on a large–scale map (such as a 1:24,000 scale map), contour lines might be spaced at 10–foot intervals, while on a small–scale map (such as a 1:250,000 scale map), contour lines might be spaced at 100–meter intervals.
The spacing of contour lines also varies depending on the nature of the terrain. In general, contour lines are closer together on steep slopes and farther apart on gentle slopes.
They are also closer together in areas of complex terrain, such as where there are a lot of hills and valleys.