A shallow spread of fire-cracked stones at the bottom of a quiet Waterford valley is not, at first glance, the kind of thing that stops you in your tracks. But burnt mounds, as archaeologists call these low, horseshoe-shaped deposits of shattered rock and charcoal-blackened earth, represent one of the most widespread and quietly puzzling monument types in the Irish landscape. Found in their thousands across the country, they date mostly to the Bronze Age, and their precise purpose remains a matter of debate. The leading theory is that they were cooking sites, where stones were heated in fire and then dropped into water-filled troughs to bring the liquid to a boil. Others have suggested ritual bathing, textile processing, or some combination of uses.

The Tinhalla example came to light not through deliberate excavation but as a by-product of infrastructure work. During the laying of a Bord Gáis pipeline in 1986, a spread of burnt and broken stones roughly eleven metres in diameter and only about fifteen centimetres thick was uncovered on the western side of a stream running through a south-to-north valley. The site was recorded by M. Gowen in fieldnotes from that year. The relatively modest thickness of the visible deposit is notable, though not unusual; the observation at the time was that most of the material probably extends further to the west, beyond the pipeline corridor, and so lies undisturbed beneath the surrounding ground. What the pipeline exposed was, in all likelihood, only the eastern fringe of a larger mound.