Look closer, though, and the soil is laced with charcoal and scattered with stones cracked and fractured by repeated exposure to intense heat. What the field holds is a burnt mound, one of the most common yet least-explained monument types in the Irish archaeological landscape.

Burnt mounds are the residue of a process that was repeated, seemingly obsessively, across prehistoric Ireland. Stones were heated in fire and then plunged into water-filled troughs or pits, bringing the water rapidly to the boil. The stones, unable to withstand the thermal shock, shattered; the discarded fragments and ash were raked aside, accumulating over time into low spreads or crescentic mounds. They date broadly to the Bronze Age, roughly 2000 to 500 BC, and while cooking is the explanation most often proposed, hot-spring bathing, industrial processing, and communal ritual have all been argued. No single purpose has been agreed upon. The site at Skaghardgannon fits the classic profile: a circular spread of heat-shattered stone and charcoal-enriched soil, sitting quietly in agricultural land, its original function still a matter of scholarly debate.