Understanding OS Maps,
Grid References and contours

The UK OS Grid System

Grid References

Map Symbols

Common symbols that you will need on your DofE Expedition include:

All maps contain a legend at one side of the map. This identifies all map symbols, as well as explaining other key information.

Map Scales

Where is North?

There are 3 Norths:

Contour lines

Contour lines are used to illustrate 3D land on a 2D map. On 1:25000 scale maps:

Uphill: Contour numbering reads up hill – in other words the top of the number is uphill and the bottom is downhill. 

Steepness of slope: The closer contour lines are together, the steeper the slope.

Setting a map - lie of the land

There are three types of features:

It is often easier to use linear features when setting the map.

Look at the map and identify where you are. It’s a good idea to do this regularly from the very beginning because it will help you keep track of where you are and avoid major errors. You might even set the map in the car park and use the location of the road to help you work out which path to take.

Look around you at the various features you can see and choose a few obvious ones (the bigger the better).

Stand still and rotate the map in your hands until the features you are looking at line up with the features on the map. For example, if the path is in front of you and there’s a stream to your left, turn the map so that the stream is to the left of the path when you look down at it.

Setting a map - compass