Contour lines join places of equal height. Their spacing shows how steep the land is, and their shapes show hills, valleys and ridges.
This lesson belongs to SPM Geography map and graph skills. Drawing a profile from contours is covered in contours, height and cross-sections.
What do spacing and shape tell you?
Read spacing first for steepness, then read the heights for direction.
| Contour pattern | Land form |
|---|---|
| Lines close together | Steep slope |
| Lines far apart | Gentle slope |
| Closed rings, heights rise inwards | Hill or peak |
| V shapes pointing to higher ground | Valley |
| V shapes pointing to lower ground | Ridge or spur |
A river normally runs along a valley floor, so a stream symbol inside a V helps confirm the reading.
Worked example: an original map with a river
An original map has a contour interval of 20 m. On the west, contours read 100, 120, 140 and 160 m, and they are packed 1 mm apart on the page. On the east, contours read 40, 60 and 80 m and are spaced 8 mm apart. A stream flows south through a V-shaped set of lines that points towards the 160 m contour.
Question: “Compare the relief on the west and east of the map, and describe the stream’s valley.”
Answer: “The west is steep, because the contours are close together and rise from 100 m to 160 m. The east is gentler, since the contours are far apart and rise only from 40 m to 80 m. The stream lies in a valley, shown by V-shaped contours pointing towards the higher ground.”
Read the contour interval first. From 100 m to 160 m is a rise of 60 m, which is three intervals of 20 m.
The mistake: reading a V the wrong way round
A common slip is to take any V as a valley. The direction matters. A V that points towards higher numbers is a valley, and a V that points towards lower numbers is a ridge or spur.
Check the heights on two neighbouring lines. If the lines curve around a stream symbol, it is a valley. If they curve around a high point, it is a spur.
Check yourself
An original map has a contour interval of 10 m. Closed rings read 30, 40 and 50 m going inwards, and the rings are 2 mm apart on one side and 9 mm apart on the other. Describe the feature and its slopes.
Answer
It is a hill, because the heights rise towards the centre (30, 40, 50 m).
The side with rings 2 mm apart is steep, and the side with rings 9 mm apart is gentle. The top is at least 50 m high.
What to study next
Practise profiles in the contour profile and slope reasoning trainer, then test the whole cluster with the map and graph skills practice set.
For a teacher who brings fresh contour maps to each lesson, see online one-to-one Geography tuition.