The walls are roughly 1.2 metres high, carefully constructed without mortar in the tradition of Irish dry stone building, and together they enclose an interior space of approximately eight metres wide by four metres deep. What makes the structure quietly puzzling is not its construction but its location: a very remote and, by all accounts, quite inaccessible spot that raises the obvious question of what it was actually for.

The enclosure was identified and described by John Loesberg, who noted its unusual configuration. One wall meets the cliff face at a straight angle, about 1.1 metres wide at that junction, while the second wall runs parallel to the rockface before curving round to join it. The cliff itself serves as a third and fourth boundary, meaning the human builders only needed to raise walls where the natural terrain did not already provide them. This is a technique with deep roots in Irish pastoral and agricultural practice, where topography was used economically to reduce the labour of construction. Loesberg compared it to a cattle or sheep enclosure, and the scale and form would be consistent with that use. But the remoteness of the site sits awkwardly with that interpretation. Moving livestock to a pen at the back of a mountain lake, in terrain described as inaccessible, would have required considerable effort, and it is not clear why a farmer would choose such a location when less demanding ground was available.