Micromorphology

Four undisturbed block samples for micromorphological analysis were taken from two phases of occupation deposits within an Iron Age wheelhouse at the site of Bornais, on the island of South Uist, in the Outer Hebrides. In thin section, the primary occupation deposit was determined to be a former A horizon of the machair that had subsequently altered during its use as a floor by trampling and by the addition of burnt soil material from the central hearth. Turf taken from an area outside of the machair had been added to the floor, presumably used as construction or flooring material, and the presence of microscopic bone and egg shell fragments indicates that meat and eggs were processed and/or consumed in the building. The second phase of floor had developed on a prepared surface made from carbonate sands dug out of the sand dune and spread over the charred ruins of the primary structure. Activities that took place on the floor include digging activities that resulted in some redeposition and reworking of the charred turf and charcoal layer, defecation by a carnivore such as a cat or dog, the spreading of relatively clean carbonate sand to maintain the floor, and the dumping of peat ash, which was presumably used as fuel in the secondary hearth.