This is a burnt spread, a type of site found across Ireland and Britain that archaeologists associate with the fulacht fiadh tradition, in which large quantities of stone were repeatedly heated in fire and then plunged into water-filled troughs to boil or heat the water. The process left behind exactly what survives here: fire-cracked stone, blackened soil, and the ghostly outline of intense, repeated activity.

The mound at Afaddy measures roughly 16.4 metres north to south and 13.2 metres east to west, rising only about 0.2 metres on its eastern side, so it sits almost flush with the surrounding ground. Its shape is the detail that makes it particularly legible: the burnt material forms a roughly horseshoe curve around a rectangular area of marly clay, approximately six metres by 2.4 metres, in the north-western portion. That clay patch, notably free of charcoal, may represent the location of a trough, the vessel into which heated stones were dropped to bring water to temperature. A spring lies just twenty metres to the west-south-west, which would have supplied the water that made the whole operation possible. The site sits in a flat valley at the base of a north-east-facing slope, and it is not alone there; four other burnt spreads have been identified along the same valley floor, suggesting this was a place people returned to over time, or that several groups made use of the same convenient geography at different points in prehistory.