Each is a fulacht fia, the Irish term for a class of prehistoric cooking or industrial site found in enormous numbers across Ireland, typically identified on the surface as a low mound or spread of fire-cracked stone and dark, charred earth. The working principle was straightforward: stones were heated in a fire, then dropped into a water-filled trough to bring it to a boil, and the discarded, shattered fragments accumulated into the characteristic mound over repeated use. The Dunmahon example documented here is the largest of the three, an irregular spread of burnt material measuring roughly fifteen metres east to west and twenty metres north to south, sitting in tillage about forty metres west of a stream.

The proximity to running water is entirely typical. Fulachtaí fia almost always appear close to streams or marshy ground, since a ready water supply was central to whatever was happening at them. What that activity actually was has been debated for decades; cooking, brewing, textile processing, and bathing have all been proposed with varying degrees of experimental support. At Dunmahon, the two companion sites lie fourteen metres to the north-east and thirty metres to the north respectively, close enough to suggest either repeated use of the same favourable location across time, or organised activity across the three spots simultaneously. The sites sit in agricultural land in North Cork, a county that has produced a particularly dense record of fulachtaí fia, many of them ploughed down to little more than a scorched spread in the soil.