What is defined as an index contour in terrain mapping?

What is defined as an index contour in terrain mapping?

• A. Every second contour line
• B. Contour lines marked thicker every fifth line
• C. Contour lines representing major elevations
• D. Contour lines with no elevation change

Answer: (B)

An index contour in terrain mapping is characterized by contour lines that are marked thicker than other lines, typically occurring at regular intervals, such as every fifth line. This visual distinction helps map readers easily identify significant elevation changes within the topography. Index contours indicate a specific elevation, serving as a reference for interpreting surrounding contour lines, which represent minor changes in elevation. This system enhances readability and comprehension of the terrain, making it easier to determine the landscape's shape and features.

An index contour in terrain mapping is characterized by contour lines that are marked thicker than other lines, typically occurring at regular intervals, such as every fifth line. This visual distinction helps map readers easily identify significant elevation changes within the topography. Index contours indicate a specific elevation, serving as a reference for interpreting surrounding contour lines, which represent minor changes in elevation. This system enhances readability and comprehension of the terrain, making it easier to determine the landscape's shape and features.