2018:769 - Knockbrack 4, Mayo

The site was identified during archaeological testing Stage (i) of the proposed N5 Westport to Turlough Road Project (A0069:E004621) undertaken by Archaeological Consultancy Services Unit in August 2018 as an addendum to testing undertaken in 2015. Due to very poor ground conditions the area was inaccessible when the main programme of test trenching was undertaken, but the dry weather in the summer of 2018 resulted in much improved conditions. The excavation was carried out between 15 October and 30 November 2018.

An area measuring 605m² was stripped of topsoil and excavated at Knockbrack 4, confirming the presence of a burnt mound located at the southern base of a small ridge of outcropping rock. The ridge sloped down to the townland boundary with Doon and it is here at the base that the peat developed in what was a very wet area when the fulacht fiadh was first used. The burnt mound consisted of fire-cracked sandstone, charcoal-stained clay and charcoal. It was sub-circular in plan, measured 14.5m north-west/south-east by 12.5m and varied in thickness from 0.08–0.52m. It was cut by a field boundary ditch that contained a small stream; this was also the townland boundary between Knockbrack and Doon. It is likely that a stream was always located within the vicinity of the burnt mound, with its location only formalized with the construction of the townland boundary. A modern pit that contained the remains of a horse burial also cut through a portion of the burnt stone spread to the south-east.

Upon removal of the burnt mound a timber-lined trough was exposed. It was sub-rectangular in plan, aligned north-north-east/south-south-west and measured 2.25m by 0.85m and had a depth of 0.4m. The base was concave, giving the trough a U-shaped profile. The trough consisted of a number of timbers, including a large hollowed-out tree trunk along the length and two upright, slightly curving planks at either end. A section of wattling and upright stakes (T17–23) extended along the eastern side.

Three radiocarbon dates were obtained: two samples of charcoal, one from the lower layer of the burnt mound in the north-east quadrant and the other from the fill of the trough, and one timber sample from the wattle screen on the eastern side of the trough. Dr Ellen O’Carroll identified the charcoal as alder and hazel respectively and the timber as alder. The burnt mound was dated to 2469–2291 cal. BC (3890 ± 30 BP; Beta-518397), the fill of the trough was dated to 1505–1396 cal. BC (3170 ± 30 BP; Beta-518398) and the wattle screen was dated to 1595–1418 cal. BC (3210 ±30 BP; Beta-518399). These would suggest a Middle Bronze Age date for the site with the charcoal from the burnt mound residual or representing older wood gathered for firewood. There was no evidence for an earlier trough at the site.

Archaeological Consultancy Services Unit, Unit 21, Boyne Business Park, Greenhills, Drogheda, Co Louth