Reading a cross-section from contour lines
Geography · Key Stage 3 · The School
From a bird's-eye view to a side view
A contour map shows height from directly above, as a set of rings and lines. A CROSS-SECTION takes just one straight line across that map and turns it into a side view — a drawing of the actual shape of the ground along that exact line, as if you had sliced through the landscape and looked at the cut edge.
Building one, step by step
Draw a straight line across the map between two points. Mark every place that line crosses a contour, and note that contour's height. Plot each of those points on a graph: distance along the bottom, height up the side. Join the points with a smooth curve, and the shape that appears is the cross-section — the actual profile of the land.
Reading the shape you have drawn
Contour lines packed closely together along the line mean the cross-section rises or falls STEEPLY at that point. Contour lines spread far apart mean a GENTLE slope. A flat stretch on the cross-section, with no height change, shows where the line crossed no contours at all — flat ground.
A line crosses contours at these heights, in order: 0m, 10m, 20m, 40m, 60m, 70m, 60m, 40m, 20m, 10m, 0m — ten crossings in total, evenly spaced along the line. Plotted on a graph, this traces a shape that rises steadily, peaks at 70m roughly in the middle, then falls away the same way it rose. That is the cross-section of a single hill, seen from the side, built entirely from numbers that started as rings on a map seen from above. Where the contours were close together — near the peak, in this example — the cross-section rises steeply. Further from the peak, where contours space out, the slope on the cross-section visibly flattens.