From small beginnings in 2010, when a number of set upright stones just visible among the pebbles on the beach indicated the presence of orthostatic settings, the subsequent excavation indicated archaeological survival on the beach below the erosion face that forms the boundary between land and high water. The presence of these deposits and their subsequent investigation has completely changed our understanding of this enigmatic mound. Initial clearance of the overlying beach material revealed the remains of an Iron Age structure. This was confirmed by an AMS radiocarbon date of 25BC-AD130 at 95% confidence for carbonized barley from a midden, which sealed flagging in one of the compartments. Work in 2012 enabled the nature of the erosion to be more fully understood indicating significant archaeological survival and potential. The sea had created terraces or steps within the archaeological mound, with each of these eroded scars being covered by re-deposited beach material.
In 2011, on the NW western side of the cleared archaeological surface, the remains of a substantial outer wall forming the arc of a large circular building seemed to form the continuation of a crescent shaped ridge at the top of the mound, and it was thought to be the outer wall of a large roundhouse of broch proportions.
A Chambered Cairn?
In 2012 this substantial wall was investigated more fully; clearance of the overlying beach material revealed a circular structure. This was formed by a number of concentric outer wall faces. Each arc of wall was backed by a stone and midden core. Rather than the expected broch, the structure of this monument more closely parallels the construction of a Neolithic chambered tomb. A wall running eastwards is suggestive of an outer-work leading into an entrance passage. Cutting into and sealing the top of this enigmatic monument were further Iron Age buildings represented by truncated flag floors and orthostats.
A close up of the concentric walls of the chambered tomb surviving under the storm beach at Swandro
For more general Orkney background information please visit our page on 'Orkney's Archaeology'
The concentric walls of the chambered tomb in the foreground, the Atlantic on the right.
Despite aggressive erosion, shown by the worn outer faces of the walls which have been battered by the sea and the constant movement of the boulder beach, this probable chambered cairn still remains intact, and has great archaeological potential.
The excavation of the seaward outer rings proved difficult, as the sea would cover these at high tide and work had to be timed to coincide with low tides, after substantial amounts of bailing. Bone from the Iron Age middens and between the concentric walls of the cairn survives well even in areas truncated by the sea. This means that the potential for in situ human remains within the tomb is high and in consequence this is an extremely important site. Re-evaluation of existing tomb assemblages are currently challenging previously held interpretations. This site offers the rare opportunity to excavate using modern methods and techniques, a tomb which in a few years' time will be completely lost to the Atlantic.
Work to the SE in 2012 saw the continuation of Late Iron Age walling on the foreshore under the boulder beach and now indicates that the Norse Hall overlies earlier settlement material.
This year’s excavations have demonstrated that the deposits at Swandro are more extensive and the deeper deposits are much earlier than initially suspected.