A burnt mound, in essence, is a heap of fire-cracked stones discarded after repeated use in ancient cooking or heating processes; stones were superheated in a fire, then dropped into a water-filled trough to bring the liquid rapidly to the boil. They are among the most common prehistoric monuments in Ireland, yet the example at Ballyhenry proved stubbornly reluctant to conform to the expected pattern.

The site came to light in autumn 2001, when Ciara MacManus carried out pre-construction testing ahead of the N11 road scheme. The area had been flagged partly because of its low, wet character, and partly because Catherine McLoughlin had already excavated a burnt-mound complex in the nearby Rathmore townland. A small deposit of heat-shattered stones was excavated in December 2001 by Emmet Stafford, and the mound that forms the focus here, lying slightly to the south, was excavated in January 2002. The archaeological deposits occupied an area of roughly 16 metres east to west by 14 metres. The mound itself measured 10 metres by 14 metres and reached a maximum depth of just 0.3 metres, its heat-fractured stones set in a charcoal-rich matrix containing quartz, sandstone, glacial stones, and a proportion of decomposed granite. Some shallower deposits to the east had been washed clean of charcoal entirely. What the excavators did not find was the trough that typically accompanies such mounds. A shallow, irregularly rounded cut toward the centre of the mound did not match the usual form, though it was noted that the addition of clay or leather sides could theoretically have made it functional for water retention. Its position, sitting between the two deepest accumulations of burnt stone, suggested that material may have been cast outward from the cut after successive uses, making it a possible secondary trough constructed after an original, unidentified feature had gone out of use. That earlier feature, if it existed, may simply lie to the east, beyond the edge of the road-take and unexamined.