Scillonian entrance grave
The entrance graves of Cornwall and the Isles of Scilly, and south east Ireland are megalithic chamber tombs of the Neolithic and early Bronze Age in the British Isles. Comparable sites are also known in Brittany and the Channel Islands. They are generally known as the Scillonian group as the greatest concentration of the tombs is found on the Isles of Scilly.
Examples include Bant's Carn and the Innisidgen and Porth Hellick Down tombs, all on St Mary's.
They consist of a narrow entrance which leads into a rectangular burial chamber covered by a small round stone cairn usually revetted with a kerb. In some examples a sill stone blocks the entrance. The walls of the chamber themselves are of either orthostat slabs or stone courses, covered with several large capstones. Both the cairn and the chamber often exploit natural stone outcrops or boulders in their construction.
Entrance orientations in Scillonian graves follow no discernible pattern and they appear to have been used for deposition of multiple cremation and inhumation burials with up to 60 individuals found at Knackyboy Cairn on the island of St Martin's. Occupation debris has also been found in the graves which implies that they were actively used sites possibly for wider ritual purposes and/or as territorial markers.
The small size and simplicity of these monuments compared with the more complex tombs being built elsewhere in Britain imply that the areas where they are found preserved older methods of burial. The earliest known finds from Scillonian entrance graves include fragments of middle Neolithic Carn Brea type ware and have led some archaeologists such as Paul Ashbee to argue that they are in fact of early Neolithic or even Mesolithic date. Much of the Bronze Age material excavated from entrance graves is considered to be related to later re-use.