From RTÉ Radio 1's The History Show, writer Mary Russell tells the story of how the very first Ordnance Survey maps of ...

Spot heights show the height of a particular point on the map. Contour lines that are close together show land that increases or decreases in height quickly. This is steep land. Contour lines that ...

Contour lines close contour lineLine on a map joining points of equal height above sea level - thus representing the slope of the land. are added to a map to show height and gradient. On OS maps ...