The endangered multi-period site, much of which is under the storm beach, is being pounded by the winter storms, making the dig a battle against time.
This year’s excavation has provided a valuable insight into both the Iron Age settlement mound and the Neolithic Passage Grave.
Two Iron Age buildings formed the focus of study this year, a building dating to the first half of the first millennium.
The removal of a flagged floor provided a glimpse of earlier levels and some in situ metalworking evidence.
Signs of an earlier stone-built tank pre-dating the floor proved of interest.
Steve Dockrill, co-director of the project with Julie Bond, said: “This was an unusually large tank. It is hoped that samples from the infill might give us some insight into its last use.”
The back of the flagged floor in the middle Iron Age building has been “stolen” by the sea, demonstrating the risk that these buildings face from the destructive power of the storms.
There is a Late Iron Age or Pictish building which proved to have a surviving hearth and as floor, as well as a doorway with intact door pivot, door jamb and bar keep, enabling the building to locked from the inside.
Steve said: “This floor proved to be very interesting as broken pieces of fired clay, slag and other indicators of metal working appeared to have been trodden into the ashy surface.
“The remains of a large elongated beach cobble was found partly covering the hearth. This stone appeared to have been set upright and its upward end showed damage consistent with it having been repeatedly struck. If we are correct in thinking that this semi underground building was used as a smithy this is a likely candidate as having been used as an anvil.”
The earliest and most interesting parts of the site are the investigations of the Neolithic Chambered Cairn.
The eroding beach portion of the tomb has revealed both the passage and evidence for the collapse of its roof.
Dr Bond said: “We are now down to the rubble infill, above this we had evidence for later infill dating probably to the first Viking settlers.
“They may well have found that the tomb was a good source of stone and they infilled the top of the passage with a number of butchered sheep, at least three cats and a coin of Eanred, a ninth century king of Northumbria.”
“What was totally unexpected was the discovery that the Passage tomb actually isn’t the earliest feature on the site.
“There are clear signs that the casement walling of the cairn overlays earlier stonework and ash layers.
“Unfortunately this area has been hit hard by the sea and much of the integrity of the lower (seaward) deposits have been compromised by the tidal movement of the sea”.
The dig is being led by the University of a Bradford and Orkney College UHI.