Where the water has cut into the bank over time, a dark layer of burnt material is exposed in section, along with what appear to be the remnants of a stone revetment, a lining or facing of carefully placed stones. These details, unremarkable to most eyes, are the signature of a fulacht fia.

A fulacht fia, sometimes called a burnt mound, is among the most common prehistoric monuments in Ireland, yet the one at Kilblaffer sits quietly in farmland with little to mark its presence. The basic function of such sites, as archaeologists understand them, involved heating stones in a fire, dropping them into a water-filled trough to bring it rapidly to the boil, and then discarding the cracked, fire-shattered stones in a crescent-shaped mound nearby. The burnt material visible in the Kilblaffer stream bank is almost certainly the accumulated debris of this process, built up through repeated use over what may have been centuries. The stones noted in section, likely the collapsed or partial remains of a revetment lining a trough or pit, suggest this was a structured installation rather than a casual fire site. Fulachtaí fia are broadly dated to the Bronze Age, though some sites have produced evidence of use across a wider span. Whether they served primarily for cooking, bathing, textile processing, or some combination of purposes is still a matter of active discussion among researchers.

The site survives in pasture, with the stream bank providing an accidental but telling cross-section through the archaeology. The exposed material in the bank is what makes this particular example visible at all; without that erosion, there would be little obvious sign of anything unusual in the field.