A watching brief undertaken on the excavation of foundations for an extension to a cottage to the south of the medieval Abbey on Iona revealed what was initially interpreted as a spread of prehistoric midden material. The watching brief was undertane by Dr Claire Ellis of Argyll Archaeology, under the terms of a condition attached to planning consent by Argyll and Bute Council, on the advice of the West of Scotland Archaeology Service. Following completion of the on-site monitoring, post-excavation analysis took place on the pottery and chipped stone assemblages recovered from the site, while samples were sent for radiocarbon dating
A date of 1000 +/- 30 BP, calibrating to 980 - 1060 AD (69.8%) was obtained from a piece of carbonised hazel recovered from the lower portion of the buried soil at the site. The pottery assemblage was found to dominated by sherds that were relatively undiagnostic in their form and fabric. However, a fragment from a shallow bowl found on site was comparable to sherds excavated in 1983 from deposits next to Iona Abbey, and from where a single radiocarbon date, 660-890 AD (95%), was obtained. Unexpectedly, a few of the pottery sherds recovered from the upper layer of the buried soil appear to date from the mid first century AD. Similarly, the coarse stone and chipped stone assemblage is consistent with a later prehistoric date. The implication of this archaeological evidence is that the buried soil identified on the site must have been exposed and actively utilised for many hundreds of years. Soil micromorphological analysis revealed that the buried soil was dominated by coarse sand and grit mixed with considerable quantities of ash, typical of the domestic hearth, as well as other domestic waste products. It is unclear from micromorphological analysis whether a midden heap was spread out and subsequently cultivated, or whether midden material has been added to natural sand and grit to increase soil fertility and structure. Given the apparent longevity of the buried soil, coupled with the apparent lack of sequential deposition of the finds, it seems more likely that manure (in the form of domestic midden) was added to the soil over some considerable period of time.
In January of this year, Dr Ellis returned to Iona to monitor the removal of topsoil within the garden ground of another house in the area to the south of the Abbey, again as a requirement of planning consent for the construction of a new extension. This revealed two thin midden deposits, overlying a bright brown silt loam or the natural bedrock. Within the two midden deposits were found sherds of early historic pottery and a considerable quantity of animal and fish bone, with occasional large fragments of charcoal. Post-excavation work on the pottery, bone and charcoal samples will be completed in due course.