But the blackened, charcoal-flecked earth and the fragments of heat-shattered stone packed into it are the unmistakable signature of a fulacht fia, a type of Bronze Age cooking or heating site found widely across Ireland. The basic principle was simple: stones were heated in fire, then dropped into a water-filled trough to bring it rapidly to the boil. The cracked, spent stones were discarded nearby, building up over time into the characteristic horseshoe-shaped mound that survives today.

This particular example, in the townland of Islands in County Kilkenny, came to light in 2006 during archaeological works carried out ahead of the M8/N8 Cullahill to Cashel Road Improvement Scheme. The mound measured seven metres north to south, five metres wide, and just under half a metre deep, its body composed of compacted black sandy silt dense with charcoal and fire-cracked stone. Beneath it lay a circular wooden trough, nearly square in its proportions at roughly 1.86 metres by 1.84 metres, with a flat base sitting 0.4 metres deep. A timber from the trough was radiocarbon dated to between 2870 and 2490 cal BC, placing its use firmly in the Early Bronze Age, somewhere between four and five thousand years ago. The site was not alone: a second fulacht fia was excavated approximately twenty metres to the west, suggesting that this patch of wet ground beside the wetlands was a place people returned to repeatedly, or perhaps used simultaneously for purposes we can now only partly reconstruct.