This one is remarkable for what does not. A small enclosure, the kind of modest circular or oval boundary of stone or earthwork that occurs throughout the Irish uplands and might mark an ancient field, a seasonal settlement, or a stock pen, was recorded on aerial photography taken in 1973 on the western slopes of the Blackwater river valley in Derreennagreer. When surveyors went to look for it on the ground, it was gone. It had never appeared on Ordnance Survey maps, which means it left no paper trace at all beyond a single frame of aerial film.

The enclosure sat on rough mountain pasture, the kind of terrain that tends to preserve early features precisely because it has been too marginal for intensive farming. What appears to have undone it was not agriculture but infrastructure. In the early 1990s, a mountain road was constructed in this part of the Iveragh Peninsula, and the most likely explanation is that the feature was cleared or buried during that work. The aerial photograph, taken by the Geological Survey of Ireland, became the only record of something that had probably stood, in some form, for centuries before being erased in the course of a single construction project. A. O'Sullivan and J. Sheehan documented the site in their 1996 archaeological survey of south Kerry, noting its absence with the careful understatement of fieldworkers who have arrived too late.