The modern road, roughly five hundred metres long and three metres wide, sits directly on top of this earlier structure, a togher, which is the Irish term for a wooden trackway laid across soft or waterlogged ground. What is now a quiet access lane was once, it seems, the only reliable way to reach Derrynaflan, a small island of firm ground within the great bog of Lurga, and the site of an early medieval monastery.

The connection between the causeway and the monastery at Derrynaflan is not purely practical; it also carries a literary echo. In the Latin Lives of St. Ruadhan of Lorrha, there is an account of a causeway crossing the bog between the monastery of Derryvella and that of Derrynaflan. In the story, Bishop Columbanus, son of Dar Aine, of Daire Mar, sent Ruadhan and his monks a gift of a cask of butter, carried in a cart drawn by two oxen. To allow the cart to pass, a wide and firm path miraculously appeared through the bog of Lurga. Whether or not the tale preserves any memory of the physical togher beneath the present lane, it speaks to how thoroughly the crossing of this bog was embedded in the imagination of the communities who lived around it.

The laneway still leads to the ruined church at Derrynaflan, and the oak planks of the older causeway remain visible at its margins in places, particularly where the modern surface has not fully obscured the earlier construction. Derrynaflan is, of course, also the site of the celebrated hoard of early Christian metalwork found in 1980, which gives the island a double significance, both as a place of early monastic settlement and as a landscape where the ground itself, peat, plank, and stone, carries centuries of quiet accumulation.