Which of the following is not a type of contour line?

• A. Index
• B. Intermediate
• C. Supplementary
• D. Median

Answer: (D)

Contour lines on a topographic map connect points that share the same elevation, letting you read the terrain at a glance. The heavy, labeled lines are index contours, which give you quick elevation references. Between those, the lighter intermediate contours fill in the elevation steps to show how steep or gentle the slope is. Supplementary contours are often drawn as dashed lines to provide extra elevation detail in areas where the terrain changes are subtle or where spacing between main contours is wide.

Median, on the other hand, isn’t a term used to classify contour lines. It’s a statistical measure and has no place in describing how elevation is represented on standard topographic maps.