Depression contours are identified by which feature?

• A. Closed contours with right angle tick marks pointing inward
• B. Dashed lines
• C. Solid red lines
• D. Blue shading

Answer: (A)

Depressions are shown on maps by closed contour lines with small tick marks (hachures) on the inside of the line, pointing toward the center. These tick marks are perpendicular to the contour and indicate that elevation decreases toward the interior, signaling a bowl-shaped low area. The other styles—dashed lines, solid red lines, or blue shading—do not represent depressions: dashed lines often mark approximate or intermittent features, solid red lines typically denote roads or boundaries, and blue shading indicates water features. So the combination of a closed loop with inward-facing hatch marks is the clear sign of a depression.