Question

What is a darker contor line usaly every fifth line?

Answer 1

Hello There! ^_^

Your question: What is a darker contour line usually every fifth line..?

Your answer: An indes contour is a contour line that is usually in every fifth line.

Hope this helps!

Answer 2

Answer: Index contour.

Explanation: Index contours are those elevation line which are represented by a thick or darker line. It is because if we draw every elevation with a simple line, its not so reliable. So making every fifth contour line dark helps us in reading the map elevation clearly without any difficulties.

   This is very commonly used in the maps and are separated at equal heights.