It is grass-covered, barely perceptible, and measures roughly twelve metres by nine. What lies beneath the surface, however, is the accumulated debris of prehistoric cooking: heat-shattered stones and charcoal-enriched soil, the signature remains of a burnt mound, one of the most common yet persistently mysterious monument types in the Irish landscape.

Burnt mounds, known in Irish archaeology as fulachtaí fia, are generally interpreted as outdoor cooking sites, most likely dating to the Bronze Age. The typical method involved heating stones in a fire, then dropping them into a water-filled trough to bring it to a boil. The stones, cracked and spent after repeated use, were tossed aside, building up over time into the characteristic low horseshoe or oval mound of scorched rubble. The Kilcaskan example sits around a hundred metres north of a stream, which fits the pattern well; proximity to a water source was essential to the whole operation. A forest drain running northeast to southwest now bisects the mound, and where the drain cuts through, a cross-section of the burnt material is exposed, varying in depth from around eight centimetres to forty-four centimetres. That sliver of exposed archaeology, visible in the drain's wall, is the clearest evidence of what the grassed-over mound conceals.