Excavation
Date 13 May 2017 - 3 June 2017
Event ID 1038973
Category Recording
Type Excavation
Permalink http://canmore.org.uk/event/1038973
NM 28683 24515 (NM22SE 5) Two trenches originally excavated in 1956/7 by a team led by Charles Thomas were re-excavated to obtain radiocarbon dates and environmental samples, 13 May – 3 June 2017.
Trench 1 (NM 28497 24553) was a long section through the monastic enclosure banks and ditch (Thomas’ Cutting 6). Detailed sections of the inner bank deposits showed a complex layering of turf bands and dumped ditch material, lying on a buried peaty soil. Micro-morphological soil samples and radiocarbon dates should establish whether the bank is multiphase in construction. The ditch was bottomed and revealed waterlogged deposits full of plant material and containing insect remains. This material has been sent to specialists for analysis. The ditch appears to show two episodes of infill. The outer bank was of different simpler
construction, bounded by a stone kerb and may be a later field boundary.
Trench 2 (NM 28662 24484) expanded on Thomas’ Cutting 11d, which had exposed an unusual dry stone wall. Excavation revealed that the wall was a revetted foundation for a structure with a curved end, possibly an apse of an early chapel, such as that at Dunfermline Abbey. The walling, which was battered, survived to a height of 1.0m, and was composed of local unfaced boulders up to 0.7m in length. The upper four courses had been rebuilt and added to in 1957 to leave a short section outlining the wall’s position at the surface. The wall was c0.8 m wide, at least 6m long, and the curved part appeared to have a well built inner face. A spread of similar large boulders encased in purplish clay lay to the E, suggesting the collapse or destruction of a clay-bonded superstructure. The structure appeared to have been demolished and robbed, and was sealed by spreads of building debris and mortar-mixing layers. This material contained medieval pottery including Scottish white gritty ware jugs, and was interpreted as debris from the construction of the 13th-century Benedictine Abbey. A series of deposits of sands, gravels and soil on the exterior of the walling included a thick layer of iron-working debris. These layers predated the demolition of the walling and were interpreted as levelling deposits, but are so far undated. The walling was built directly on a peaty buried soil and appeared to be the first feature constructed in this part of the monastic enclosure. Later features included a massive stone-pit associated with the renovation of the Abbey church around 1900, and a roadway associated with the Iona community renovations in the 1930s.
Trench 3 consisted of two small trial trenches in the field to the S of the abbey precinct. These were located to try to locate a broken field drain which was causing flooding and leading to puddling of the deposits by cattle. Trench 3a (NM 28656 24393), located a disused water pipe which
cut through surviving archaeological deposits consisting of a layer of burnt material. This layer contained several sherds of handmade pottery including craggan ware type, and iron slag. These deposits lay within a sub-rectangular enclosure measuring c30 x 50m, previously revealed by
geophysical survey undertaken for the National Trust for Scotland. Parallel furrows in the subsoil beneath these deposits appeared to be plough furrows predating the post-medieval period. Trench 3b (NM 28638 24395)
revealed a broken rubble drain which had been repaired with a plastic pipe, but the area was continually flooded and no further investigation took place. Documentary references refer to an old well in this area, Tobar Odhrain.
Geophysical survey of the NW corner of the monastic enclosure and around the chapel of Cladh an Disirt was also undertaken and is reported above. Archive: University of Glasgow then NRHE
Funder: Historic Environment Scotland
Website: https://www.gla.ac.uk/schools/humanities/research/
archaeologyresearch/groups/iona/
Ewan Campbell, Derek Alexander and Cathy MacIver – University of Glasgow
(Source: DES, Volume 18)
