Dunyvaig Castle Evaluation and Geophysical Survey
Date 12 August 2018 - 31 August 2018
Event ID 1089785
Category Project
Type Project
Permalink http://canmore.org.uk/event/1089785
Area between NR 40580 45458, NR 40910 45600, NR 40788 45890 and NR 40485 45748
A programme of work was undertaken, 12 – 31 August 2018, as part of the Dunyvaig and Hinterland Assessment Project. The work aimed to evaluate Dunyvaig Castle and its hinterland in preparation for a larger project exploring Dunyvaig and its role in the environmental, economic, social and political history of the western seaboard. Dunyvaig Castle is a scheduled ancient monument and the fieldwork was
conducted with the scheduled monument consent granted by Historic Environment Scotland.
Islay Heritage undertook an initial electrical resistance survey of the castle and its immediate landward approach in August 2017. This survey was continued in 2018 to the NE with the maximum extent reaching 240 x 120m, but narrowing as the width of the promontory narrows towards the castle in the extreme SW. The survey used a RM15 Geoscan resistance meter with twin probe configuration, 0.5m traverse spacing and 1m interval readings. In addition to the electrical resistance survey, a ground penetrating radar survey was conducted, comprising two lines across the alleged siegeworks situated at The Plateau, c200m NE from the castle, and four lines across the interior of the outer courtyard of the castle.
The electrical resistance survey has revealed significant archaeological potential across the area in the form of numerous high resistance anomalies. These include major N/S and NW/SE linear anomalies, which may represent the line of the old road leading to the castle. There are several possible structures and enclosures both in the immediate vicinity of the castle and further away. Parallel
linear anomalies showing rig and furrow cultivation on two different alignments are clearly visible.
The evaluation consisted of three main trenches. Trenches 1 and 2 were located inside the courtyard of the castle and Trench 3 targeted a high resistance area coinciding with the visible earthworks c60m to the NE. Three smaller satellite trenches, Trenches 3A, 3B and 3C, were excavated around the main Trench 3 as additional questions were raised by the shape of the earthworks.
Trench 1 was a T-shaped trench that for the main part (15 x 3m) ran along the inner face of the courtyard wall and perpendicular to the axis of Buildings A and B, as designated by the RCHAMS (1984). The northern end of Building B and its junction with the courtyard wall were located in the W end of the trench. The eastern end contained open remains of a subterranean structure usually referred to as a ‘well’. A smaller projection (5 x 2m) was positioned perpendicularly to the N over the courtyard wall. Building B abutted the courtyard wall with its gable end built against its inner face. The walls and the rubble related to the collapse of this building were overlain by a stepped turf construction, which extended across the entire length of the courtyard wall and was interpreted as the refortification of the ruined stone walls of the castle. These were built as two parallel masonry walls with a 1m wide intramural space running between them and representing either an intramural passage or a staircase. On the outside of the courtyard walls the
excavation revealed traces of an earlier partially robbed substantial mortared structure, the remains of which were reused as the footings for the castle wall. Inside Building B, the initial rubble collapse was overlying a burnt layer of turf and clay, which may have been a collapsed roof. This layer was overlying more substantial rubble collapse, which was overlying a burnt clay floor surface. The floor was not excavated, but on its surface under the rubble was a remarkably well-preserved lead seal stamp, found near the gable wall of the building. The stamp was largely legible with an inverted inscription reading ‘IOANNIS CAMPBELL DE CALDER’ around the Campbell coat of arms.
On the reverse were stylized initials DM with date 1593 over the leaf pattern. Outside the building, a midden deposit was excavated along the eastern wall containing well-preserved animal bone, shell, charcoal, small iron objects, several pieces of worked flint and a compressed musket ball. The ‘well’ was exposed and examined for structural stability and this identified collapse of its stone facing at the depth of 1.2m, making it unsafe to proceed without adequate shoring.
Trench 2 was an L-shaped trench positioned across the mouth of the sea gate and projecting inwards into the courtyard of the castle. The position of the trench was influenced by the absence of any high resistance anomalies in the geophysical results, posing the question about possible use of this area as a midden. As it turned out, the low resistance of the area came from a massive accumulation of redeposited turf, which was brought in and built upwards across the sea gate opening. The technique employed to stack the turfs appears to be much the same in appearance as the one used to reinforce the ruined courtyard wall seen in Trench 1. A smaller sondage aligned with the middle of the sea gate was excavated through the turf revealing a substantial amount of rubble, uwhich was overlying partially visible structure perpendicular and central to the sea gate. This included a substantial kerb, which might represent one side of a possible slipway. In the NE part of Trench 2, the redeposited turf was overlying burnt collapse and abutting the wall of a burnt building, which by its alignment and location is probably the S end of Building E, previously described as open-ended by the RCAHMS (1984).
Trench 3 was positioned across the T-shaped earthworks located c60m NE from the castle. The trench revealed substantial dry stone walls with evidence for rebuilding and reuse of an earlier structure. The SW/NE oriented part of the building was abutting a protruding bedrock knoll to its NE. An entrance was located at this side of the structure with a parallel stone-lined open drain running in front of it. The interior deposits consisted of rubble collapse above what appeared to be the remnants of a burnt turf roof. Below this, there was a roughly cobbled gravelly floor surface with additional traces of burning. In the SW corner of the trench there was a clay-lined oven or a small kiln filled with burnt material. The interior rubble and the underlying occupation
produced many finds, including rotary quern fragments, pottery, metal artefacts, which included a couple of musket balls, a large iron object, possibly a hammer, and a significant number of worked flint artefacts.
Three smaller trenches, Trenches 3A, 3B and 3C, investigated less pronounced earthworks and gauged the overall morphology of the structures. Trench 3A encompassed a bedrock outcrop with a rock-cut basin, which was situated c10m to the S from the T-shaped structure. Trench 3B extended from the outside of the N wall of the T-shaped structure to a low curved bank, which upon excavation turned out to be collapsed dry stone wall of a possible enclosure or a structure. In Trench 3C, large rubble was overlying several
stone boulders set into gravel deposits. These boulders may have been part of a structure, but its morphology could not be determined.
In conclusion, the evaluation brought forth a considerable amount of information, with only the main stratigraphic and structural evidence being summarised here. There is a clear parallel in the fate of all three buildings sampled by the excavation in terms of their destruction by fire. Inside the castle, one of the main discoveries was the refortification of the castle with turf defences all around the courtyard circuit and across the opening of the sea gate. This refortification occurred after the masonry walls of the castle had collapsed, as documented in the account of the 1615 siege and bombardment, and after the buildings in the courtyard, or
at least Buildings B and E, were destroyed by fire. The turf defences, being the latest part of the sequence in the castle, may well relate to the MacDonald uprising in 1647.
Archive and report: NRHE and WoSAS
Funder: Islay Heritage and University of Reading
Darko Maričević, Robert Fry, Thomas King and Steven Mithen –
Islay Heritage and the University of Reading
