The site at Earlsrath is what archaeologists call a fulacht fia, a type of outdoor cooking place found in enormous numbers across Ireland, typically consisting of a water-filled trough, a nearby hearth, and a mound of heat-shattered stone left over from repeated use. Stones were heated in a fire and dropped into the trough to boil water; the cracked, blackened fragments that resulted were thrown aside, accumulating over time into the characteristic low mounds that still dot Irish fields today. What makes Earlsrath quietly notable is the density of these sites in a single area, and the precision with which excavation allowed one of them to be dated.

The site came to light in 2007 during archaeological work carried out ahead of the N9/N10 Kilcullen to Waterford road improvement scheme. Excavators found a natural hollow on the slope, filled with black silt, charcoal, and heat-shattered angular stone sitting above an earlier deposit of pink sand, the whole spread measuring roughly fifteen metres north to south. At the south-east corner of this hollow lay a subrectangular trough, about three metres wide and half a metre deep, with steep sides and a flat base. Traces of a single course of sandstone blocks along its southern and western edges suggest it was once stone-lined, though most of that lining had not survived. Just to the west, an earth-cut pit running perpendicular to the trough contained a hearth, and a sample of alder wood taken from it was radiocarbon dated to between 918 and 815 cal BC, placing activity here firmly in the late Bronze Age. A post-hole just outside the trough to the south-east hints at some kind of timber structure, perhaps a simple shelter or a frame used in the cooking process. Three further fulachta fia were excavated in the same immediate area, suggesting this was not an isolated episode of use but part of a repeatedly visited, purposeful landscape.