Barra, Allt Chrisal

NL69NW 7.05 6418 9776.

T17: This large collapsed circular stone structure measures some 11m in diameter, with internal divisions and a courtyard enclosure. The site forms a substantial, easily visible mound with hundreds of medium-sized blocks of stone scattered across it. On the N is an annexe 6.7m by 2m and to the E an enclosure 8m by 15m abuts the main structure. It is tentatively dated to the late Iron Age from a few fragments of pottery recovered from rabbit burrow outcast and from the appearance of the structure. Armit considers this to be an Atlantic roundhouse, but Branigan and Foster are of the opinion that it is more likely to be a wheelhouse. Work on the site was limited to a detailed measured survey of the stonework and no excavations were carried out. The survey, however, showed that several phases of building are represented, including a rectangular structure which could be much later than the wheelhouse, which it apparently superecedes. It appears to be much older than farmstead NL69NW 7.06 and may be of medieval date.

I Armit 1992c; K Branigan and P Foster 1995; NMRS MS/595/3.

NL 642 977 Excavation was begun of the suspected wheelhouse at the preferred site of Allt Chrisal. The excavation is planned as a study of the effects of rabbit infestation on substantial stone structures. Excavations this year focused on the rectangular structure built at the back of the circular house and on the enclosure, apparently of a garden plot, to the E of the house. The rectangular structure, similar to one attached to the wheelhouse at Allasdale 3km to the N, was built partly over the circuit wall of the wheelhouse and was certainly a later addition. No unequivocal dating evidence was found for this structure. The enclosure to the E contained a largely stone-free soil and was probably a cultivation plot rather than animal pen. About 500 sherds of plain black pottery were recovered from this soil but no decorated or featured sherds were identified; dating is therefore problematic. It is hoped that continued excavation in 1997 will yield more diagnostic material.

Sponsor: Historic Scotland

P Foster 1996

NL 642 977 Excavation of the Iron Age wheelhouse (T17) concluded and completed the survey and excavation of the monuments (T15?29) begun in 1988 in the Allt Chrisal area (Foster 1996). The site showed considerable structural damage caused by burrowing rabbits and to a lesser degree rats, and was excavated over a period of three years to 1998, in part to assess this burrowing damage. In order to track the displacement of material around the site all finds of pottery and

flintwork, bone being dissolved in the acid peat soil, were given a unique number and individually plotted by EDM.

In 1997 excavation began within the wheelhouse revealing a complex, and at times ephemeral, sequence of late occupation phases, whose structural remains occupy a position either on top of or just within the upper internal structural elements. Several crude circular or semi-circular stone foundation settings overlay the wheelhouse superstructure while a small rectangular building was built incorporating the upper portions of the wheelhouse western internal radial partition walls. The entrance to this building was from the W, but this was an opening that had been constructed at a much earlier period and may even have been an integral part of the wheelhouse construction, although there is also a southern doorway that could be the primary entrance. The dating of these phases is highly problematical and must rely upon future analysis of the associated ceramics; very little is currently known about local 1st millennium pottery, the period most likely to apply to these structures.

Under the late building phases the wheelhouse deposits appear to have consisted not of distinct layered floor levels, but of a continuous floor build-up of trampled peat soil and hearth ash. The central fireplace confirmed this apparent continuous build-up of material, starting as a neat hearth contained within a circle of stones which became overwhelmed as the red and orange burnt peat ash mounded up until the fireplace finally occupied the whole of the central area within the house.

Within each internal compartment excavation of the lower deposits down to the primary floor level proceeded in half sections. At the northern, upslope side of the house, excavations unexpectedly reached the subsoil and it became clear that no single primary floor deposit was in situ overall and that the wheelhouse had been constructed without any levelling platform against the hill slope. This complication close to the end of the allotted excavation time caused us to abandon a proposed programme of soil sampling at the floor level and to leave the unexcavated lower deposits for future investigation and analysis. The internal area of the building was refilled with soil to protect the unstable stone wall divisions and the unexcavated floor deposits. Much of the collapsed outer, southern wall skin was rebuilt to conserve and stabilise the rest of the structure.

Sponsors: Historic Scotland, University of Sheffield.

P Foster 1998