Do closely spaced contour lines indicate a steep slope? - Answers

A contour line (also known as isopleth) on a topographic map connects points of equal elevation or depth. The steepest way up or down is in the direction perpendicular to the contour line at any given point. This gradient on a topographic map is at its greatest when the lines are close together, thus the slope is steepest. Note that a contour map does not have to be topographic. Any value mapped in two or three dimensions such as temperature, barometric pressure, or wind speed can have contour lines connecting adjacent points of equal value. Again, moving away from a contour line in a perpendicular direction will yield the greatest change in the value of the quality being recorded.