Roughly 35 to 40 metres across, this unplanted gap is the most visible sign of what may be a fulacht fia, a type of prehistoric cooking site found in large numbers across Ireland. The typical fulacht fia consists of a horseshoe-shaped mound of fire-cracked stone beside a trough and a water source; the method involved heating stones in a fire and dropping them into a water-filled trough to bring it to boiling point. They date mostly to the Bronze Age, though the tradition may have persisted longer in some areas.

What makes the Carrigane site quietly telling is what the historic Ordnance Survey maps reveal. Across all editions, the southern part of the present plantation is shown not as woodland but as rough pasture running along the banks of a watercourse, with drier ground on either side. That combination, low-lying and damp ground beside a stream, is precisely the kind of setting that fulachta fian consistently occupy. The vegetation gap visible today, a circle of absent trees in an otherwise planted landscape, preserves, perhaps inadvertently, a memory of the ground conditions that made the spot significant in the first place.