This is a fulacht fia, a type of prehistoric cooking site found across Ireland in considerable numbers, typically identified by a horseshoe or crescent-shaped mound of heat-shattered stone accumulated beside a water source. The Clogharevaun example measures roughly twelve metres east to west and eight metres north to south, rising only about sixty centimetres above the surrounding ground. It opens to the north, and the Clogharevaun River runs immediately along its southern edge.

The relationship between the mound and the river is not quite what it once was. When Cody recorded the site in 1989, he noted that the southern edge of the mound had already been cut away, a casualty of river straightening works carried out at some point between 1838 and 1892. Before that intervention, the fulacht fia would have sat roughly ten to twelve metres north of the water rather than immediately beside it. Burnt stone is still visible in the river bank near the western end of the mound, material displaced or exposed by that same engineering work. The deliberate straightening of watercourses was common practice in nineteenth-century Ireland, carried out to improve drainage on agricultural land, and it has left many archaeological features along riverbanks either damaged or subtly repositioned in the landscape. Here, the consequence is that the mound now appears almost to be sitting in the river's lap, which was not its original relationship with the water at all.