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contour line, elevation would remain constant. Contour lines show
elevation and the shape of the terrain. They’re useful because they
illustrate the shape of the land surface, its topography, on the map. The
numbers which are featured on each line represent the exact height of

the land at points along that line. The patterns created by the lines
show the shape of the land. As a person becomes more familiar with
the patterns, he or she is able to immediately identify different types

of landforms. A pattern which resembles two circles with a space
between them, for example, can be recognised as being two hills and a
saddle (a dip between two areas of higher land). The slope can also be
identified using contour lines. The closer the contour lines, the steeper

the slope is.
A contour interval is the difference in height between contour
lines. Contour lines always increase or decrease by the same amount.

This means that if one contour line represents points 50 metres above
sea level and the next contour line shows points at 100 metres above
sea level, then the third contour line will be 150 metres above sea

level. In this example, the contour interval is 50 metres.
Contour lines are a map’s way of showing you how high the land
is. They join together places of the same height and form patterns that

help us to imagine what the land actually looks like.
According to ‘Naismith’s rule’, which is very important to know,
the closer together the contour lines are, the steeper the land is.
Contour lines that are wide apart show us that the land is flatter.

When you're travelling across steep landscapes (where contour lines
are very close together) it will add time on to your journey. Naismith
said that you should allow an extra minute of walking time for every

10 metres of height that you climb.
Contour lines are usually drawn at 10 metre intervals on a 1:50
000 scale map and at 5 metre intervals on a 1:25 000 scale map.

Task 3. Answer the questions, using the active vocabulary.

1. What is the function of contour lines? What do they represent?
2. What do you know about a contour interval?

3. Can you define and explain ‘Naismith’s rule’?
4. How are contour lines drawn on topographic maps?

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