What do hatchures on contour lines indicate?

Hatchures on contour lines are a specific cartographic feature that indicate depressions or concave areas on a topographic map. When contour lines are drawn with short, hachured markings pointing toward higher ground, they signify that the area is lower than the surrounding land. This is crucial for interpretation, as it helps map users identify where terrain dips down, which can affect navigation, water flow, and understanding the natural environment.

In contrast, flat areas are represented by widely spaced contour lines, while valleys tend to be shown through broader, U-shaped curves connecting lower elevations. Summits, or peaks, typically are indicated by closed contour lines but do not include hatchures. Understanding this distinction is essential in SAR operations, where terrain assessment is key for planning and executing rescues effectively.