Contour lines — Geography, 7–10 years
Contour lines help us see how high or low the land is on a flat map. Geography, 7–10 years.
What contour lines show
A contour line joins places that are at the same height above sea level. On a map, each line is like a step on an invisible staircase: crossing a line means the land rises or falls by a set amount. Lines close together show a steep slope; lines far apart show a gentler one.
Why use contour lines?
A photograph can show a hill, but it does not tell us exactly how high it is or how hard it would be to climb. A flat map also cannot simply draw every slope in side view. Contour lines solve this problem by turning height into a pattern that hikers, builders and rescue teams can read from above.
Reading a hill
A map says its contour lines are 20 metres apart. The bottom of a hill is marked 100 m, and the next lines are 120 m, 140 m and 160 m. A house beside the 140 m line is 40 m higher than the bottom. If the lines are packed together on one side, that side is the steeper route.
The common mix-up
It is easy to think that more contour lines always mean a taller hill. They do not: the number depends on how large an area the map shows and how far apart the height steps are. A small, steep hill may have many lines, while a broad, gentle hill may have fewer. Check the numbers, not just the number of lines.
Planning a real route
Walkers use contour lines to choose a route that is not too steep. Engineers use them when planning roads, bridges or buildings, because water flows downhill and foundations need suitable ground. A map can therefore help someone decide not only where to go, but also which path is safer and easier.
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