This is not an act of later carelessness but something stranger: evidence that the wall and the stone row belong to different moments in time, and that the landscape here has been arranged, rearranged, and eventually swallowed by bog over a span of millennia.

Two sections of what are termed pre-bog walls survive on the ridge, meaning walls that were already in place before the surrounding blanket bog grew up and eventually buried them. The first runs for approximately 80 metres along a west-northwest to east-southeast axis across the ridge summit, passing through the stone row. The second lies around 100 metres to the north of a prehistoric enclosure on the same ridge, curving from west through north to east across the brow of the hill before disappearing into uncut bog at both ends. Palaeobotanical study, the analysis of ancient plant remains preserved in peat, has allowed researchers to date both walls with some precision. Samples taken from directly beneath each wall were radiocarbon dated, producing determinations of 2370 plus or minus 60 years before present and 2390 plus or minus 90 years before present respectively, placing their construction at roughly 400 BC, in the Irish Iron Age. The research was published by Molloy and O'Connell, and by Gibbons and Higgins, in 1988. What those walls were organising, and what relationship they bear to the stone row and enclosure they intersect and neighbour, remains an open question. The bog preserved them; it did not explain them.