CST Level 1 Land Surveyor Certification Practice

What is a contour interval?

1. A line of constant elevation

2. The difference in elevation between adjacent contours

3. A measure of horizontal distance between contour lines

4. Half the vertical spacing of contour lines

The correct answer is: The difference in elevation between adjacent contours

A contour interval is defined as the difference in elevation between adjacent contours on a map. This measurement is crucial because it allows surveyors and users of topographic maps to understand the steepness or flatness of the terrain being depicted. When contour lines are drawn on a map, they represent points of equal elevation. The spacing between these lines can indicate the gradient of a slope; closely spaced lines suggest a steep incline, while widely spaced lines indicate a more gradual slope. The specific elevation difference represented by the contour interval provides essential information about the terrain and is fundamental in various applications such as land development, floodplain analysis, and construction planning. The other options provided do not accurately describe a contour interval. While a line of constant elevation does refer to a contour line itself, it does not convey information about the interval. The horizontal distance between contour lines, although important in understanding terrain, does not define the contour interval. Lastly, stating that the contour interval is half the vertical spacing of contour lines is incorrect, as the contour interval is the full difference in elevation, not a fraction of it.