Somewhere in the north-east corner of a tillage field in County Cork, a ringfort once stood, and its existence is now known almost entirely through a circular shadow. Visible only from the air, the site shows up as a soil mark, a subtle variation in the colour and moisture of ploughed earth that betrays the ghostly outline of a circular enclosure roughly thirty metres across. At ground level, there is no bank, no ditch, no trace of anything at all.

A rath, as ringforts of this type are often called in Ireland, was typically an enclosed farmstead of the early medieval period, its perimeter defined by an earthen bank and external ditch, enclosing a family's dwelling and outbuildings. The example at Carrigleagh has been levelled, most likely through centuries of cultivation, until the earthwork itself has entirely vanished. What survives is the memory of the soil beneath: the disturbed, organically different ground where the bank and ditch once lay, which absorbs water and nutrients differently from the surrounding field and so registers as a faint stain when seen from above. Local knowledge corroborated what the aerial photograph suggested, preserving at least the fact of the place even after the place itself had gone.