What does every fifth contour line represent?

What does every fifth contour line represent?

• A. A heavier brown line
• B. A lighter brown line
• C. A blue line
• D. An index contour line

Answer: (A)

On topo maps, contour lines show elevation. Every fifth contour line is drawn thicker and often brown to stand out as an index contour line. This heavier line provides a quick reference with its elevation, letting you read elevations across the map without counting every thin line. Between index contours, the thinner lines fill in the steps to show the terrain’s shape. The blue lines, by contrast, indicate water features, not elevation intervals. So the heavier brown line is the visual cue that identifies the fifth contour line as an index reference.

On topo maps, contour lines show elevation. Every fifth contour line is drawn thicker and often brown to stand out as an index contour line. This heavier line provides a quick reference with its elevation, letting you read elevations across the map without counting every thin line. Between index contours, the thinner lines fill in the steps to show the terrain’s shape. The blue lines, by contrast, indicate water features, not elevation intervals. So the heavier brown line is the visual cue that identifies the fifth contour line as an index reference.