These are fulachtaí fia, a type of prehistoric burnt mound found widely across Ireland, typically Bronze Age in origin. The standard interpretation is that they served as outdoor cooking stations: stones were heated in a fire, dropped into a water-filled trough to bring it to a boil, and meat was cooked in the superheated water. The process shattered the stones, and it is the accumulated debris of those fractured rocks that forms the mounds visible today.

This particular site, surveyed by Michael Connolly during a study of the Lee Valley area in 1996 and 1997, is a well-preserved example of the classic kidney shape that characterises many fulachtaí fia. The mound rises 0.80 metres above the surrounding ground and measures 14 metres north to south by 9 metres east to west. Its trough area, the central hollow where the water vessel would have sat, opens to the west and drops roughly half a metre below the crest of the mound. All three sites in this cluster contain significant quantities of shattered red sandstone, the broken remnants of the heating process carried out here, probably repeatedly, over many generations. The marshy ground, lying approximately 150 metres north of the River Lee, would have provided a reliable water source, exactly the kind of setting these sites consistently favour across the Irish landscape.