A contour line is a line drawn on a topographic map to indicate ground elevation or depression. A contour interval is the vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line.
What Do Lines on a Contour Map Indicate?
A contour line is a line joining points of equal elevation (height) above a given level, such as mean sea level. A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.
The interval of the contour lines is an important factor. If the contour interval is large, the individual lines will not convey the shape of the terrain well, but if the contour interval is too small, the map will be too crowded with lines.
The lines on a contour map are drawn to show how the land lies. They are like ‘snapshots‘ taken at different altitudes. Each line represents a different height above a datum, which is usually mean sea level.
The closer the contour lines are together, the steeper the slope. If the lines are far apart, the slope is gentle. If the lines are very close together, the slope is very steep.
If the lines are parallel, the slope is uniform. Contour lines never cross each other because they represent points of equal elevation. Index contours are usually heavier and darker than intermediate contours. They are usually drawn at
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