It measures roughly twelve metres long, six and a half metres wide, and less than a metre high, and to a casual eye it might read as nothing more than a natural rise in wet terrain. In fact it is a fulacht fia, a type of prehistoric cooking site found in considerable numbers across Ireland, particularly in low-lying, waterlogged areas close to a water source.

The term fulacht fia, sometimes rendered as fulacht fiadh, refers to the characteristic horseshoe-shaped mound left behind when a Bronze Age cooking method was repeated over time. The basic process involved heating stones in a fire, then dropping them into a water-filled trough to bring it to a boil. The stones, fractured and spent by the repeated thermal shock, were raked out and discarded beside the trough, gradually building up the mound of dark, crumbly burnt material that archaeologists recognise today. The Oughtihery example, sitting as it does in boggy ground beside a stream, fits the typical profile almost exactly. The location is no accident: proximity to water was essential, and low-lying wet ground helped preserve the organic and burnt material over the millennia. What remains here is essentially a slow accumulation of discarded cooking debris, compressed by centuries of peat growth and now heavily overgrown.