What geographical feature is illustrated on a map by contour lines forming concentric circles?

Contour lines that form concentric circles on a map indicate a hill. These lines represent points of equal elevation, and when they are arranged in circular patterns, it signifies that the elevation increases towards the center of the circles. As you move outward from the center, the elevation gradually decreases, illustrating the shape of a hill.

In contrast, a valley is depicted with contour lines that form a V shape, pointing upstream, where the elevation decreases towards a low point. A plain would typically have straight, widely spaced contour lines that suggest little elevation change, indicating flat terrain. A plateau would show relatively flat terrain with contour lines that are closely spaced at the edges, indicating steep sides leading to a flat top. Therefore, the presence of concentric circles is a clear indicator that the geographical feature represented is a hill.