Roseberry Topping is a geological landmark found on the edge of the Cleveland hills overlooking the village of Great Ayton. It's distinctive conical shape is due to the sandstone and shale geology and a collapse of one side due to mining activity in the early 1900's. The summit of this hill is topped with a triangulation pillar.
Between 1936 and 1962 the Ordnance Survey erected a series of triangulation points around the UK as part of a project known as the "retriangulation of Great Britain". These fixed locations were mounted on a high piece of land with direct line of sight to neighboring points. This allowed their exact horizontal position to be calculated . Nowadays, digital mapping techniques and GPS systems have made these structures all but redundant. The pillar was looking very clean thanks to a recent coating of white paint used to cover up graffiti from visitors who insist on leaving their mark. Triangulation pillars were used to map the shape of the land and not elevation however many had a dual function.
Mounted on the side of this pillar is an Ordnance Survey benchmark. These flush brackets were used by surveyors to calculate the elevation from a known height, usually mean sea level. Just for the record, the sumit of Roseberry Topping is calculated at 320 metres (1050 ft.) above sea level.