2016 Knowe of Swandro Excavation
Evaluative excavation continued upon the eroding beach at Swandro, Rousay, Orkney for a 4 week season in July 2016. The archaeology is suffering from erosion from the sea which has cut into a settlement mound (Iron Age to Norse) developed upon the eastern flank of a Neolithic chambered cairn. Previous seasons have established the presence of a sequence of structures which has been exposed by the sea cutting into the archaeology forming a series of terraces. The erosion has provided an opportunity to examine and sample this archaeological sequence. Unfortunately the deposits surviving at the lowest terrace have suffered from extensive erosion with much of the midden material having been washed away and the larger structural stones having been smoothed by the movement of water and beach material.
The Chambered Cairn
The outer casement wall of the Neolithic chambered cairn is butted by a single faced alignment of stones, suggestive of a retaining wall. This was first observed in the 2012 season and again in 2015, when a much greater degree of erosion was noted. In 2016 this feature was investigated further in order to determine whether an old ground surface or underlying archaeology had survived the effects of the erosion by the sea. A number of large water worn boulders were found to be re-deposited, implying the movement of large 'storm thrown' rocks. These sealed a dark yellow sand and a black compacted sand containing decayed seaweed with no surviving evidence of any anthropogenic deposits or an in situ old ground surface. Despite this sequence of re-deposited material in the scoured area seawards of the cairn wall, the remains of a reddish ashy midden deposit was found to be sealed by the secondary retaining wall.
The entrance passage leading into the chambered cairn was also defined in 2015, upon the uppermost (landward) erosion terrace. The passage walls are single faced and the upper infill formed by a layer of small angular stone (shillet) containing copper alloy fragments, large fish and mammal bone appeared to reflect late activity. This was confirmed by the finding in post excavation of a coin of EANRED, King of Northumbria 810-840 AD, together with the near complete skeleton of a cat. This disturbance and infilling might represent Viking period activity. Work in 2016 continued to define the top of the passage and to assess the nature of this later activity. The further excavation of the passage revealed more faunal remains including of several sheep displaying metal butchery marks. This deposit sealed large angular rubble which appears to be the infill of the passage.
Looking down into the entrance passageway of the Neolithic chambered tomb, filled with rubble. The horizontal black-and-white scale is 1 metre long
Structure 1: A truncated Mid Iron Age Roundhouse
This roundhouse is represented by just one segment of its circumferential cells, the interior and southern portion having been lost to the sea. The circumference of the building is formed by orthostats; the floor of the northern radial cell was formed by a single flag, which had been made to fit the cell. Several notches had been cut into the flag, which appear to be post settings. It seems likely that this would have supported a mezzanine level around the circumstance of the structure. The presence of such mezzanine structures is paralleled by Middle Iron Age remains at Old Scatness, Shetland.
The badly damaged remains of the Middle Iron Age roundhouse, much of this building has already been destroyed by coastal erosion
Structure 2: A Late Iron Age Roundhouse
Definition of the upper eroded terrace of the beach identified the remains of what appeared to be half of a cell-like circular structure. In 2016, investigation indicated that an orthostatic divide with flagging either side which had been identified in 2015, were found to be clearly later elements forming a modification to the building. These were removed to reveal the original form of the building, the curved line of orthostats together with a door sill (threshold stone) indicating a western entrance. The seaward section demonstrated a greater degree of erosion and did not survive. A floor level was formed by large flags with evidence of orthostatic radial divisions. Entering this structure via the threshold stone, one of these radial orthostats blocks any turn to the left (north/landward side), confining movement to the centre or to the right. This phenomenon of barring entry to the left has also been observed within other Iron Age roundhouse structures in the Northern Isles at Old Scatness (Shetland). The flag floor and the hearth are clearly part of a sequence of floors representing several modifications to the building as the remains of part of a rectangular stone tank could be clearly identified under the flags.
The flagged floor of the Late Iron Age roundhouse, the western walls of which have been destroyed by the sea
Structure 3: the Pictish Smithy
Structure 3 is a cellular structure with structural features suggesting a Pictish date, mostly still sealed by the northern landward section. The southern wall was identified and excavated first and revealed evidence of an intramural cupboard, adjacent to a complete in situ cupboard. The contexts in the lower sequence under the rubble infill were found to contain some evidence of metal working with finds of slag, small crucibles and mould fragments together with evidence of fragments of copper alloy. A series of steps were found to lead from the north (landward) section into the building, in a curved passageway whose stones demonstrated wear consistent with rubbing caused by the passage of the past occupants. The presence of a threshold stone in the narrow passage, together with a bolt hole clearly indicates that there would have been a physical door dividing the passage and the central area of the structure.