Roughly eighty centimetres beneath the heather-clad surface of Timahoe Bog in County Kildare, a road lies waiting. It is not a dramatic discovery in the way of a grand timber trackway, but something quieter and more puzzling: a thin layer of grey, stony marl, between twenty and twenty-five centimetres thick, pressed down onto an even thinner bed of compacted vegetation. Together they form a gravel and stone trackway running on an east-northeast to west-southwest orientation, traceable for ten metres along the northern face of a turf bank at the western edge of the bog. Someone, at some point, laid down a surface here deliberate enough to survive burial by centuries of accumulating peat.

When the Irish Archaeological Wetland Unit from University College Dublin examined the site in March 2004, they found not one road but four distinct archaeological horizons, each sealed above and below by natural peat. What made the site particularly interesting was the character of the lowest peat layer: it was fen peat, at least ninety-five centimetres deep, rather than the raised bog material that blankets most of the surrounding landscape. Fen forms in waterlogged ground fed by mineral-rich water, and it typically predates the development of raised bog, which builds up over time as Sphagnum moss accumulates and the land gradually domes upward. Finding fen peat beneath the road either pushes the trackway's origins back to a considerably early date, or suggests that the transition from fen to raised bog happened unusually late in this part of Kildare. The four phases of construction ran through the full length of the exposed section, though the earliest phase was absent from a partial cross-section cut at the northeastern end, which may mean it was narrower than the later phases, or that successive builders shifted the line slightly with each rebuild.