On a topographic map depressions look a lot like hills. They will appear as a series of closed circles one inside the other. However, to distinguish them from hills, depressions have hashmarks on all of the contour lines. This allows us to easily identify them as depressions.
Another important difference between hills and depressions is that the outermost contour line on a depressions always has the exact same value as the last normal contour line on the map.
