Navigation: Map Basics

Being able to read a map and find your way around the hills is an essential skill for all hill walkers. Even the most experienced hill walkers get lost sometimes, and practice is the real key. Get your map out on your next sunny walk and take some time to learn how to use it when making a mistake won’t have serious consequences.

Map Styles

There are currently two main map styles available to British mountain users: Ordnance Survey (OS) and Harvey. OS maps are produced for a wide range of users, while Harvey maps are specifically produced for mountain users, meaning that they include more detailed and accurate information about the tops of complex rocky summits, with significant rock features precisely marked.

Contours

Hills, slopes and mountains are represented on a map using contour lines. A contour is a line drawn on a map that joins points of equal height above sea level. For 1:25 000 scale maps the interval between contours is usually 5 metres, although in mountainous regions it may be 10 metres. The closer contour lines are together, the steeper the slope. By correctly interpreting contours, a 3D image of the land can be built in your head, showing how high and how steep mountains and valleys are. This skill takes a lot of experience and time to develop.  To denote general rocky ground Harvey maps also change the contour colour.

Scale

Map scale refers to the relationship (or ratio) between distance on a map and the corresponding distance on the ground. For example, on a 1:50 000 scale map, 1cm on the map equals 50 000cm (500 m) on the ground. OS maps are available at 1:50 000 and 1:25 000 scales and cover the whole of the British Isles. Harvey maps cover many mountain areas and use 1:25 000 and 1:40 000 scales. A large-scale map (1:25 000) includes more detail, but covers less area than a smaller scale map (1:50 000). As a result 1:25 000 is a very popular scale for mountain users. 1:50 000 maps have brightly coloured contours to help interpret the land shape, but don’t include useful smaller features such as walls and fences. Which leaves 1:40 000, a scale that sits in the middle - large enough to include accurate rock features and physical boundaries, but small enough to cover a large area of land. Don’t just stick with one scale or manufacturer, experiment and see which suits you best.

Legend

Every map has a legend which defines the various features of that specific map. For example, colour can be used to show different types of terrain, like farmland, moorland or woodland. Variations of dotted or dashed lines indicate rights of way such as public footpaths and bridleways. Studying the legend will really help you find your way around your map.

Use It Don’t Lose It

Once out and about you need to keep your map handy, and protected from the elements. For mountain use, a waterproof map or map cover is essential, and some maps are made with a lightweight plastic, which is waterproof, tear resistant, and lightweight. Just make sure it’s secure and won’t blow away in a sudden gust of wind!