This one, on farmland at Barnageeragh in County Dublin, is more elusive: it appears and disappears with the farming calendar, revealing itself only as a dark stain in the soil when a plough turns the ground. What lies beneath is a fulacht fia, a type of prehistoric cooking site found in considerable numbers across Ireland. The term refers to a mound of fire-cracked stone and charcoal-rich earth, the accumulated debris of a process in which stones were heated in a fire and then dropped into a water-filled trough to bring it to a boil. Thousands of these sites survive across the country, most dating to the Bronze Age, though the one at Barnageeragh has not been excavated and its precise date is unconfirmed.

The site was recorded and compiled by archaeologist Geraldine Stout, with a subsequent update by Christine Baker uploaded in November 2014. What the record captures is less a monument than a set of observations taken across more than one visit. The ground here slopes in two directions at once, falling from south to north and from east to west, a topography that would have suited a site dependent on water collection or drainage. On earlier visits, when the field had been ploughed, the burnt soil spread was clearly visible at the surface. By the time of the most recent recorded visit, the crop had been harvested and the ground left fallow, meaning the surface had been broken but no discolouration was apparent. The site, in other words, had effectively gone quiet again.

Barnageeragh is not a visitor site in any formal sense, and access depends entirely on the condition of the surrounding farmland. There are no markers, no signage, and no guaranteed view of anything at all. The best chance of seeing the characteristic dark spread of burnt and charcoal-rich soil is after autumn ploughing, when disturbed ground brings the buried material back to the surface. The slope of the field, running down toward the north and west, is itself a useful orientation point if you are trying to locate roughly where the feature sits. Anyone with a serious interest in fulacht fia distribution in the greater Dublin region would find the recorded observations here, sparse as they are, a useful data point in understanding how these sites cluster across different soil types and drainage conditions.