A dry stone pyramid is not what you expect to see in a playing field in Durham, but it is what is to be seen in Cotherstone playing field in Teesdale, thanks to sculptor and master dry stone waller Ewan Allinson from Middleton-in-Teesdale.

The bulk of it is Baxton Law walling stone supplied by Dunhouse. It also has limestone from Hulands Quarry (Aggregate Industries), Whinstone from Forcegarth Quarry (Cemex) and Ganister (a hard, dense local sandstone from Harthope Quarry run by Richard and Colin Scott). All the stone was donated.

Unveiled on the 6 July, the pyramid is both sculpture and playground climbing equipment, with tunnels into a central chamber large enough for children to stand in.

Above the chamber, hidden in the stonework, is a time capsule filled with items collected by pupils at Cotherstone School and from the community at large.

It explores aspects of local geology and quarrying as well as Norse mythology attached to Baldersdale (to which Cotherstone is a gateway), Balder being the doomed god of joy.

You can read more about the pyramid and the strange and chilling story that inspired it on the Stone Specialist website at bit.ly/playground-pyramid.