When crossing a stream valley from one side to the other, how are contour values encountered?

When crossing a stream valley from one side to the other, how are contour values encountered?

• A. The last contour value on the descending side is the first contour value on the ascending side.
• B. Contour values completely reset to zero at the stream.
• C. Contours on opposite sides are unrelated.
• D. Contour lines are not drawn near streams.

Answer: (A)

Contour lines represent elevations on a continuous surface. As you move from one side of a stream valley toward the valley floor, you encounter contour lines with decreasing elevations, and as you continue up the opposite slope, you encounter the same elevation values again in reverse order. In other words, the last contour line you cross before the stream on one side is the first contour line you meet after crossing to the other side. There’s no resetting to zero at the stream, and contours are still drawn near streams to show how the land rises away from the valley floor.