It is a togher, an ancient trackway constructed from wood laid across boggy or marshy terrain to allow people to cross ground that would otherwise swallow them whole. This particular example is modest in its dimensions, just one metre wide and fifteen centimetres deep, but its construction is precise and deliberate: lengths of worked hazel brushwood, each averaging about two and a half centimetres in diameter, laid longitudinally and oriented on an east-west line. Someone cut that hazel, shaped it, and placed it carefully. The bog then did what bogs do, preserving the whole arrangement in its cold, acidic, oxygen-poor embrace.

Toghers of this type are classified by their construction method, and a class 3 togher uses longitudinal rather than transverse timbers, distinguishing it from the more familiar corduroy-style trackways where poles are laid crosswise like the rungs of a ladder. Hazel was a common choice for such work throughout prehistoric and early medieval Ireland, being flexible, relatively straight when coppiced, and available across much of the island's woodland. The Irish boglands have yielded hundreds of such trackways over the years, many of them identified and recorded through systematic wetland survey work. The material from Derrylough is part of that broader archive of wooden roads, each one a small trace of the effort ordinary people once made simply to move through a difficult landscape.