2006:1476 - Sonnagh, Mayo

This site was excavated between 15 May and 13 June 2006. It was newly identified during centreline testing (A020/003) and was fully excavated in advance of the construction of the N5 Charlestown bypass. This fulacht fiadh was enveloped in peat and consisted of a large burnt mound, a well-preserved wood- and moss-lined trough and a random concentration of timbers, some of which were worked. It was located at 70m OD.
On identification, the mound was oval-shaped with a peat-filled hollow to the south where it overlay the trough. It measured 13.5m by 10.5m and had a maximum thickness of 1.5m. The mound consisted of compact heat-fractured stone (90%) with concentrations of charcoal and peat throughout (10%). Two possible burnt flakes of flint were recovered from the base of the mound and are the only small finds from the excavation.
The trough was cut into the peat below the mound. It was rectangular in plan with overall measurements of 2.4m by 1.3m. The fill was comprised predominantly of heat-fractured stones, which were larger and less degraded than those present in the mound. There were also concentrations of charcoal and occasional hazelnuts within the fill. The sides of the trough were built up with brushwood and roundwood timbers, which were poorly preserved towards the top and better preserved towards the base. They measured on average 0.88–2.2m long by 0.09–0.15m in diameter. Ten split planks were laid across the short axis of the trough to form its base. Some of these were notched to slot into the retaining posts. A total of thirteen stakes/posts were present in the corners of the trough. Most of these timbers had wedge-cut ends with some chisel cuts and pencil points.
There was an outer lining of moss with a maximum thickness of 0.07m surrounding the sides and base of the trough. A layer of grey gritty sand lay directly under the moss at the base of the trough. It was 0.06m thick and in turn rested on a series of twelve roundwood timbers, which comprised a second wooden base. These were aligned east–west across the short axis of the trough similar to the split planks in the upper base of the main lining. This in turn rested on another 0.07m layer of moss which rested on another layer of grey gritty sand which rested on a third layer of timbers. This third layer of base timbers consisted of seven roundwoods, two of which were split. These timbers rested on a final 0.07m-thick layer of moss which rested on a basal layer of sand that was 0.06m thick. This trough was set into a cut in the peat that measured 2.1m by 1.3m by 0.42m deep. A biconical tin bead with ribbed decoration was recovered from the upper moss lining below the trough base.
A random concentration of timbers occurred in the peat to the south-east of the trough over an area measuring 7m by 4.5m. It included some large roundwood timbers surrounding a felled tree trunk and a series of smaller timbers. Twenty of these timbers had cut ends. A similar layer of timbers occurred at a lower level in the same area and included a further six with cut ends.