Excavation

Date 15 June 2015 - 10 July 2015

Event ID 1026045

Category Recording

Type Excavation

Permalink http://canmore.org.uk/event/1026045

ND 4542 8688 Excavation work continued, 15 June – 10 July 2015, at The Cairns (known by RCAHMS as ‘The Cairns of the Bu’), as part of on-going research on the Orcadian Iron Age. The work focused on the main open area trench, c25 x 25m, and a 10 x 10m area in the northern extension immediately

to the NE of the main trench.

One aim was to enhance understanding of the massive Atlantic roundhouse or broch-like building (Structure A) that makes up a large part of the archaeological mound at The Cairns. Structure A, a monumental thick-walled roundhouse, possessing an overall diameter of c22m, was further defined

and explored internally. Substantial samples were taken from the deposits on the NE interior of the broch. A series of rough flagged surfaces were encountered similar to those seen in previous seasons further to the S. Beneath and to the W of the flags carbon rich soils and rough stone slab bases indicated occupation materials late in the life of the broch. Beneath these deposits a fairly sterile orange clay indicated a formally laid clay floor, and beneath this deposit lay more black organic-rich soil. Beneath this yet more sterile clay appeared to indicate an earlier laid floor surface, this time a saddle quern and quern rubber were found to have been deposited, placed on edge within the clay in a likely ‘structured deposit’. It appears that there is a succession of well-preserved formally laid-out floors and occupation deposits within the broch, at least in this northern sector, and this holds out great potential for assessing the uses of the broch from its beginning to the end.

The entire suite of deposits was sampled on a grid and will hopefully provide substantial volumes of environmental information and attest to the types of activities underway inside the broch through time. This information will be supplemented in future seasons when more of the interior of the broch will be excavated. One surprise discovery inside the broch was a very well-preserved built underground structure in the northern interior and very close to the inner

wall face. The structure is essentially of the ‘well’-type and has a set of some half a dozen stairs leading down to a partly rock-cut, partly finely coursed and corbelled chamber, c2m beneath the presently reached surface of the broch. Initial tests suggest that there is upwards of a metre depth of deposits in the base of this structure. The discovery of the ‘well’ is particularly welcome since one of the major aims of the project is to investigate the role and history of Iron Age subterranean structures and this feature will be fully excavated in future seasons.

In the northern extension trench (Trench M) work continued with the investigation of the large curvilinear feature that has been previously identified in geophysical survey and is thought to represent a large enclosure ditch surrounding the broch and settlement. The ditch was indeed located and, though c1.2m deep in this section, it was found to be very broad, and extended beyond the boundary of the extension trench. A network of drains was found to

sinuously cut through the boulder clay at the base of the ditch/gully. In several places where capping stones appear to have been lifted off in antiquity there were numerous edge-set quern rubbers placed in the sides of the drain gully forming its sidewalls.

In the western part of Trench M a series of building remains and features relating to activity after the ditch had been infilled were also investigated. The area was found to be as rich as the previous field season in evidence for metalworking. Around 30 fragments of well-preserved clay moulds were discovered and represent the debris from casting projecting ring-headed pins, rings and possibly penannular brooches. These were accompanied by metalwork itself including, broken copper alloy pins, and a ring. Importantly, crucible fragments and numerous pieces of slag and other residues and waste, as well as a large clay furnace feature itself, were found to suggest actual in situ metalworking was taking place in this corner of the site. The entire suite of materials is heavily indicative of a well-preserved and rare window on to bronze working at the end of the Middle Iron Age, which will continue to be a focus for excavation next season.

Excavation also continued to define the stratigraphic relationships between the souterrain, Structure F, and adjacent and overlying features. The southern, entrance end of the souterrain passage was found to extend further than previously thought and appears to make use of, or at least cut through, an older small circular building or cell composed of well-built orthostats.

Work also continued on the post-broch suite of buildings and activity areas in the western area of the main trench. Attention was primarily directed to Structure B, a complex multi-phase arrangement of rectilinear and cellular wall lines, features and adjoining rooms and discrete buildings. A well-preserved set of articulated red deer remains were found to partially underlie one of the hearths in this area and may represent a foundation deposit made during the initial stages of this phase of the use of the B area. Small finds from this area included a very finely carved conical gaming piece.

Archive: Orkney SMR and Orkney Museums Service (intended)

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

Martin Carruthers – Archaeology Institute, Orkney College, UHI

(Source: DES, Volume 16)