Between 1883 and 1886, geologist G.H. Kinahan documented what he found: a narrow, gallery-like construction stretching about 5.2 metres long and just over a metre wide internally. The walls consisted of upright stone flags nearly a metre high; three on one side, four on the other, with a tall stone sealing off what seemed to be the northern end. Two additional flags flanked the open southern entrance. Kinahan couldn’t quite decide what to call it, first labelling it a ‘lusca’, typically meaning an underground passage or souterrain, then later calling it a ‘fosleac’, a term for dwellings built from flags or long stone blocks.

The mystery deepened when the structure vanished from local memory and maps. Though Kinahan carefully marked its location on his field maps, now held at the Geological Survey Office in Dublin, it never appeared on Ordnance Survey maps. Modern searches of the area he indicated have turned up nothing but thorn bushes, leaving researchers to wonder whether the structure was dismantled, buried, or perhaps mislocated. Its true purpose remains uncertain; it could have been anything from a burial chamber to a storage facility or even an early dwelling.

The surrounding landscape holds its own enigmas. Two nearby sites in Edenacarnan South, known locally as ‘Marcagh’s Knowe’ and ‘Marcagh’s Stable’, were marked as antiquities on 1834 Ordnance Survey maps. When antiquarian Fagan examined them in the 1840s, he reported that ramparts enclosed the summit of each knoll, suggesting they might have been defensive structures or ceremonial sites. Today, they appear to be nothing more than natural hillocks, their archaeological features, if they ever existed, long since eroded or removed. These tantalising glimpses into Donegal’s prehistoric past serve as reminders of how much ancient heritage has been lost to time, agriculture, and the Irish weather.