What is a cross-section?
A cross-section is a side view of the shape of the land along a straight line between two points on a topographic map. It shows how the height of the ground rises and falls — whether the land is hilly, valley-like or flat.
Steps for drawing
- Join the two points with a straight line and lay the edge of a strip of paper along it.
- Mark every place where the line crosses a contour line and note its height value.
- Transfer each mark to a grid: horizontal axis = distance, vertical axis = height.
- Join the points with a smooth curve to give the land profile.
Key idea
A cross-section is drawn from contour heights. Contours close together = steep slope; contours far apart = gentle slope.
From a cross-section we can interpret the shape of a slope. When contour lines are close together, the slope is steep; when they are far apart, the slope is gentle. A cross-section also helps us judge whether two places can see each other (line of sight). This skill is important in the SPM Geography paper for describing the true shape of the land surface.