Map makers use lines and shading to depict topographical features.
Topographic maps are created by using contour lines. These lines mirror the landscape of a particular area, identifying the shapes, locations, and elevations of landforms that lie within it.
Contour Lines
Contour lines consist of index lines, which are marked with the elevation, and intermediate unmarked lines. There are four intermediate lines for every marked index line.
Slopes
Contour lines that are drawn close together indicate steep terrain. As the slope levels out the contour lines grow farther apart. Following the marked index lines will tell you if you are going uphill or downhill.
Hills
Hills are depicted by a series of closed contour lines, or irregular circles. The steeper the hill, the less space between the irregular circles.
Closed Depressions
Closed depressions are also shown by a series of closed contour lines. In this case the contours are shaded using a series of hachure lines. These are short parallel lines used to indicate certain types of topographical features on a map.
Streams
When crossing a stream valley, contour lines will be drawn with a "V" shape pointing upstream.
Overhanging Cliffs
Contour lines are not meant to cross each other. One exception is those depicting an overhanging cliff. In this case, the line that represents the lowest elevation is dashed.
Tags: contour lines, closed contour, closed contour lines, Contour lines, index lines
