Which phrase identifies the standard difference in elevation on a topography map? index contour

contour interval

scale bar

topographic symbol

contour interval.

The contour interval is the standard difference in elevation on the topographic maps. The contour lines themselves represent closed circular lines that connected dots that have the same elevation. The standard contour lines are set at an exact same interval, be it 5, 20, 100 meters. That elevation distance is actually representing the contour interval itself, which is the vertical distance between two contour lines.