gen-define-topographic-contour-lines-and-give-one-short-worked-e-8a95

Define topographic contour lines and give one short worked example.

# Topographic Contour Lines **Definition:** Topographic contour lines are imaginary lines on a map that connect points of equal elevation above a reference level (usually sea level). They represent the three-dimensional shape of the land surface on a two-dimensional map. ## Key Properties: - Each line represents a constant elevation - Lines never cross or split - Closer spacing = steeper slope - Wider spacing = gentler slope ## Worked Example **Problem:** A hill has contour lines at 100m, 120m, 140m, and 160m elevation. Two hikers measure the horizontal distance between the 100m and 160m contours on opposite sides of the hill: - North side: 300m horizontal distance - South side: 150m horizontal distance Which side is steeper? **Solution:** **North side:** - Elevation change: 160m - 100m = 60m - Horizontal distance: 300m - Slope = 60m ÷ 300m = 0.20 or **20% grade** **South side:** - Elevation change: 160m - 100m = 60m - Horizontal distance: 150m - Slope = 60m ÷ 150m = 0.40 or **40% grade** **Answer:** The south side is steeper (40% vs 20%). This matches the principle that closely-spaced contours indicate steeper terrain.