What is the purpose of contour lines on topographic maps?

Contour lines on topographic maps serve the critical function of providing elevation information. These lines connect points of equal elevation and visually represent the three-dimensional terrain on a two-dimensional surface. Each contour line reflects a specific elevation above a reference point, usually sea level, allowing users to understand the shape and steepness of the terrain.

By analyzing the spacing and arrangement of contour lines, one can infer important details about the landscape such as slopes, valleys, ridges, and various landforms. For instance, closely spaced contour lines indicate a steep slope, while lines that are farther apart suggest a gentler incline. This representation is essential for activities like land use planning, outdoor navigation, and environmental studies, where understanding the elevation and relief of the land is necessary.

The other options, while related to geographic information, do not accurately represent the primary purpose of contour lines. Distances between landmarks or features like rivers and lakes fall outside the specific elevation-focused function of contour lines, and while some maps may include urban infrastructure, that is not the purpose of contour lines themselves.