That discolouration, along with dense concentrations of charcoal and the occasional fragment of burnt bone, is what survives of a corn-drying kiln used in County Cork around the middle of the fourth century AD, a time when Roman Britain was still functioning to the east and Ireland was developing its own agricultural traditions largely beyond imperial reach.

Corn-drying kilns were a practical solution to the damp Irish climate. Grain harvested in wet conditions needed to be dried before it could be stored or ground, and a kiln, typically a pit or stone-lined flue heated from below, allowed farmers to do this with some control. The example at Rath-Healy was figure-of-eight in shape, roughly 2.5 metres long and up to 1.5 metres wide, and divided into two connected chambers: a shallower one to the north, about 25 centimetres deep, and a deeper southern chamber reaching around 60 centimetres. It was this southern chamber that bore the evidence of sustained heat. Radiocarbon dating of charcoal recovered from the fill returned a calibrated date of approximately AD 350, and seed analysis from the same deposits identified the crop being processed as predominantly barley. The kiln came to light not through targeted archaeological investigation but as a consequence of road construction: it was one of two such kilns excavated in 2003 along the route of the N8 Rathcormac-Fermoy Bypass, with a second example located roughly 44 metres to the north-east. The proximity of the two kilns suggests an area of some agricultural intensity, or at least repeated use of the same landscape for the same purpose over time. The findings were subsequently published by O'Connell and Linnane in 2006.