Benchmarks in Stonehouse

Click on the icons, and follow the link for images and height above sea level, etc.

Benchmarks are carved marks or plates placed by the Ordnance Survey. They define locations and the height above sea level for map making and assisting in defining legal borders, drainage etc. They are still (in theory) protected by law, but in practice only certain ones are now needed e.g. for measuring flood risk. GPS & sophisticated software & communications can now locate points to about 1 mm.