It is, in fact, the surviving trace of a bivallate enclosure, meaning one defined originally by two concentric banks or ditches, a form of earthwork associated broadly with early medieval settlement and activity in Ireland. The interior measures roughly 43 metres by 36 metres, and a curving segment of field bank still arcs around the north-western edge, hinting at the outer circuit that once enclosed the whole.

The enclosure was recorded on the Ordnance Survey six-inch map of 1839, where it was depicted as a clear oval feature with two distinct rings, its proportions suggesting something substantial enough to have been legible in the landscape nearly two centuries ago. By the time more recent observers came to look, the double-bank structure had largely dissolved into the hillside, leaving only the sunken interior and that single bank fragment as physical evidence. It is, at least in part, still detectable as a vegetation mark on aerial imagery, the differential growth of grass and other plants betraying the buried boundaries beneath, a reminder that earthworks erased at ground level often persist in subtler forms above it.