To a passing eye it might read as a natural rise in boggy terrain, but the blackened, fire-cracked material packed into it tells a different story. This is a fulacht fia, one of the most common yet most quietly baffling monument types in the Irish archaeological landscape.

Fulachtaí fia, the plural form, are ancient cooking sites, probably dating in most cases to the Bronze Age, though some have produced earlier or later dates. The typical arrangement involves a trough dug into the ground near a water source, a hearth for heating stones, and a mound of the shattered, discarded stones that built up over repeated use. The method works by heating stones in a fire and then dropping them into a water-filled trough, bringing the water rapidly to the boil. The crescent or horseshoe shape of the mound, familiar from more extensively excavated examples elsewhere in Ireland, forms as the spent stones are cast aside after each use. At Coolgarriff, the mound is circular rather than the classic crescent, and the marshy ground nearby would have provided a reliable water source, exactly the kind of setting these sites typically favour. The mound material, burnt and fragmented, is the accumulated evidence of fires lit and stones broken across what may have been many seasons of use.