Elevation features are described on maps by use of contour lines. A contour line on a map is the line you would trace out on the terrain if you were to walk along a path of constant elevation. Here are some commonly observed terrain features translate into contour lines:
Hills: closed curves of decreasing size. Inner curves are at higher elevation than outer curves, and the peak is within the innermost curve.
Valleys: these appear as a series of “V” shaped curves. The point of the “V” always points toward the head of the valley, and when there are streams in the valleys the “V” points upstream.
Saddles: The space between peaks can be recognized by its hourglass shaped contour lines.
Gentle slopes: slow rises in elevation over a long horizontal distance are represented by widely-spaced contour lines.
Cliffs: since they represent dramatic changes in elevation over a short horizontal distance, cliffs are represented by closely-spaced contour lines.