What shape do contour lines form to indicate a valley?

Contour lines are an essential feature in topographic mapping, representing changes in elevation across the landscape. When it comes to indicating a valley, these lines typically form a distinctive U-shape or V-shape. This formation occurs because the contour lines will point upwards toward higher ground, with the apex of the V or U shape indicating the highest elevation surrounding the valley.

As water flows downhill, it tends to create valleys, and the contour lines visually depict this downward slope. The opening of the V or U shape points in the direction of the uphill slope, highlighting the low area of the valley where water would accumulate. Understanding this relationship is fundamental for navigation and interpreting the terrain effectively.

In contrast, straight lines would suggest a flat, uniform area without significant elevation changes, circles indicate peaks or pits rather than valleys, while wavy lines don't convey the clear directional flow that characterizes valleys. Thus, recognizing the U or V shapes formed by contour lines is crucial for land navigation and determining the topography of an area.