Excavation

Date 2019

Event ID 1122536

Category Recording

Type Excavation

Permalink http://canmore.org.uk/event/1122536

ND 4542 8688 Excavation work continued in Summer 2019, as part of on-going research on the Orcadian Iron Age. The principal open-area trench, some 47 x 23m, was a focus of the work, (Trench areas: Z, M and Q), and a further extension on the NW side of the site.

As in previous recent seasons (DES 2018, 153-5; DES 2017, 148-150; DES 2016, 134-5) work concentrated on four main areas of the site: the Broch interior, the extramural complex of buildings and features on the northern side of the exterior of the broch (Trench areas: M and Q), elements of the extramural complex (Structure J) on the southern side of the broch exterior, and the souterrain (Structure F) located outside the E-facing entrance of the broch.

Within the broch (Structure A), work continued across key areas of its interior. In the large western ‘room’, floors and a heavily heat-affected hearth, filling much of the western room, were fully excavated to reveal yet another hearth beneath. This is the third consecutive hearth juxtaposed in this location, and this one is especially large and impressive with large quantities of associated in situ and raked-out peat ash. A very finely set and substantial pavement arced around its northern side. This hearth appears to be the primary hearth of the west room. Excavation of organic occupation material, close to the southern edge of the hearth, yielded a very small shard of glass, possibly from a dumbbell type bead or toggle, and a bronze ring. The west room of the broch appears to have always been a busy, and perhaps important area, set innermost within the interior. Large quantities of animal bone, and substantial ‘slabs’ of smashed pottery vessels present in the gaps between major floor slabs appears to further testify to the very active use of the zone.

A large pit on the southern edge of the west room was also investigated. The edges of the pit were lined with charcoal and thick, clean yellow clay, and these elements may well indicate that a lining, or a wattle structure had once lain within the pit. This pit may have seen use as a cooking pit or could have been used in some ‘industrial’/craft process. The excavated sides of the pit also contained large sherds of pottery apparently smashed in situ against the lining. As excavation of the pit progressed a section leading between it and the nearby portion of broch inner wall face was dug. This revealed the lowest course of broch masonry and the natural glacial till that it sat upon. The primary occupation deposits of the broch have thus been reached.

Excavation also continued in the NE room of the broch. The occupation deposits here, were composed of ashy material, and investigation supported findings from previous season that there is a complex sequence of floors and occupation present. Glacial till was again reached on the edge of the sample grid in this room, showing that the earliest surviving broch activity deposits have been reached here also. Work also continued in the south room of the broch, adjacent to the entrance to the mural staircase. Deposits here were notably dark and rich in carbonised organics. An array of stone tools, ceramics, and bronze objects were recovered.

Beyond the broch itself, excavation continued just outside the eastern entrance of the broch in the area taken up by a souterrain (Structure F) that had been constructed in the immediate aftermath of the broch. The souterrain floor deposits were substantially excavated and revealed a complex array of many layers and some more discrete deposits across the interior of the passage. A greenish layer encountered across much of the souterrain had the appearance of cess, meanwhile a discrete reddish-brown deposit near the souterrain entrance could be deposited into the souterrain from above, via a void feature previously identified in the stone roof. This material will be chemically analysed to attempt to obtain clarity on the nature of the substance.

Work also proceeded in the northern area of the main trench. This large area of contiguous buildings and features represents the northern portion of a multi-phase extramural complex surrounding the broch. Immediately outside, and to the N of, the broch entrance, work in Structure O revealed more details and extent of this substantial rectangular building. Structure O was previously recognised to be sealed and partly filled by rubble emanating from the demolition of the broch in the late-1st to Mid-2nd Centuries AD. This season, excavation of the upper rubble over the east side of Structure O revealed yet another revetment wall and associated paving that post-dates the broch and the abandonment of O. This revetment appears similar to previously excavated revetments that apparently formalised activities on the surface of the broch mound in the late Iron Age. It seems that multiple lines of revetment in an almost tier-like arrangement were built probably in the 5th or 6th Centuries AD.

Directly to the NE of Structure O work also recommenced on another large extramural building, Structure Q. This building, the scene of work in previous seasons, is another elongated one, which excavation revealed to extend some 15 metres in length. At its southern end, Structure Q had been thought to abut the northern wall face of Structure O, however, the appearance of another gable-end wall dividing the run of Structure O and Q showed that there is a further building between the two (Structure R). Structure Q yielded pottery, stone tools, and a small annular yellow glass bead of Guido’s Class 8 type, very similar to another found in the same structure last season.

Work also recommenced on the southern end of Structure K, which had been the scene of copper alloy metalworking late in its life. The southern gable end of this building was identified rendering a sense of the layout of the structure. It was a large building some 12m in length. It may well have been one of the buildings of an extramural village contemporary with the broch occupation.

Work on the southern extramural area of the site also continued this season. This concentrated on another of the extramural buildings (Structure J), which sits snug against the southern exterior wall face of the broch. This building probably extended and contracted at different parts of its history. The fuller outline of the building was revealed this season showing that the previously investigated kidney-shaped portion of the building is just one room of a considerably larger, and more complex, original form.

Over twenty Iron Age buildings have now been identified at The Cairns. Radiocarbon dating so far indicates a range in time from, at least, the 1st Century BC to the 8th Century AD, or later. Several structures are now fully excavated and others will be completed over the next field seasons.

Archive: Orkney SMR and Orkney Museums Service (intended)

Funder: Orkney Islands Council and Archaeology Institute, University of the Highlands & Islands

Martin Carruthers – Archaeology Institute, Orkney College, UHI

(Source: DES Vol 20)