What are the three different types of contour lines?

The types of contour lines are critical elements in understanding topographic maps, which are essential for navigation and terrain analysis in military operations. The correct answer identifies the three main types: index, intermediate, and supplementary contour lines.

Index contour lines are the most prominent lines, typically marked at regular intervals on the map (often every fifth line), and they are usually labeled with their elevation value. This helps map readers easily gauge elevation changes across the terrain.

Intermediate contour lines connect points of equal elevation but are not labeled. They fill the space between the index contours and provide a continuous depiction of the terrain's shape, indicating more subtle elevation changes.

Supplementary contour lines, often thinner than index lines, represent elevation in situations where the terrain is relatively flat or where the depiction of detailed topography is necessary. These lines increase the level of detail in areas where the elevation may otherwise be difficult to decipher.

Understanding these types of contour lines allows military personnel to better interpret maps for planning and executing operations, ensuring effective movement and positioning in varied landscapes.