Scale is the relationship between a distance on a map and its corresponding distance on the ground. For example, if the scale on a map is 1 cm = .5 km (1cm:.5km), on the map, 10 centimetres would equal a distance of 5 kilometres (10 × .5 = 5 km).
On an Ordnance Survey (OS) map, the same scale can be shown in three different ways (see figure 1).
Scale is given as a ratio. The ratio 1:50 000 means that any one unit of measurement on the map corresponds to 50 000 similar units on the ground.
Linear Scale is a ruled line divided into kilometres and parts of a kilometre (or into miles and parts of a mile). It allows us to measure distance directly from the map.
1. Scale*
*This scale will be included in your exam papers.
Statement of Scale simply states what the scale is (in this case, it is 2 cm to 1 km).
Maps can be divided into two distinct types: z„ z„
A B
Small-scale maps show large areas in little detail. Large-scale maps show small areas in greater detail.
C
Examine the three images A–C and answer these questions: Working with others:
1. Match the maps with the following scales: (1:8 500), (1:20 000 000), (1:50 000)
2. Which map has the largest scale?
3. Which map shows the greatest detail?
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4. Which map would be useful for: (i) Someone wishing to locate a city in Ireland? (ii) Someone wishing to locate a town or village in Ireland?
(iii) Someone wishing to locate a particular landmark in a town or county?
(iv) Someone wishing to plot a route around a city or town?
