The Ordnance Survey (OS) is the mapping agency for Great Britain. It creates up-to-date paper and digital maps for individuals and businesses to use.
Maps show objects as being much smaller than they are in real life. The relationship between the features on the map to the real size on the ground is called the scale. Scale is shown as a ratio, eg 1:25,000 means that 1 cm on a map represents 25,000 cm or 250 m in real life.
OS maps come in different scales:
Grid references accurately locate places on a map. Every OS map has a grid, which is shown using faint blue lines. The lines across the bottom of the map are called eastings as they travel towards the east. The lines up the side of the map are called northings as they travel towards the north.
Four-figure grid references locate a place or object within a grid square. Four-figure grid references are found as follows:
Six-figure grid references locate a place or object within a specific part of a grid square. Six-figure grid references are found as follows:
On a map, height is shown in metres above sea level. Spot heights show the height of a particular point on the map.
Contour lines are added to a map to show height and gradient. On OS maps they are shown as thin orange or brown lines, some of which have the land height written on them. The lines join areas of equal height:
We can use contour lines to create cross-section diagrams of landscapes. This helps to match contour lines on the map to landscape features in real life, eg hills, valleys and spurs of land.