Conquer the CST Level 1 Land Surveyor Certification 2026 – Map Out Your Success!

A contour line is a specific type of line drawn on a topographic map that connects points of equal elevation. This means that every point along a contour line is at the same height above a particular reference, often sea level. Understanding this is critical in interpreting topographic maps, as it allows surveyors, engineers, and outdoor enthusiasts to visualize the terrain's shape.

When a contour line circles around an area, it can indicate hills or depressions, and the spacing between these lines can provide insight into the slope's steepness. However, what is fundamentally true is that the primary function of a contour line is to define a continuous horizontal plane at a fixed elevation, making the identification of equal elevation the core aspect.

The other options do not accurately describe the nature of contour lines. For instance, they do not inherently represent steady elevation increase or decrease solely by their existence; rather, the change in spacing and elevation labels indicates that. Similarly, the concept of navigable waters is not relevant to contour lines, as these lines are not used to indicate water bodies but land elevation instead.