This is a pond barrow, a type of prehistoric burial monument defined precisely by that inversion: rather than the mounded profile most people associate with ancient graves, the enclosed area is deliberately sunk, creating a depression ringed by a low bank. The effect, especially after centuries of weathering and agricultural activity, can be easy to miss entirely.

When archaeologists examined the site in May 1983, they found a barrow roughly nineteen metres in diameter, its enclosing bank rising only about half a metre above the surrounding field. The edges of that bank were indistinct, suggesting considerable deterioration over time, and the dished centre sat a full metre below the bank's crest. Pond barrows are generally associated with the Bronze Age and are far less common in Ireland than the more familiar mounded forms; their function is not fully understood, though they are typically found in funerary or ceremonial landscapes. The Slatefield example is recorded as poorly preserved, which is not unusual for earthworks that have spent millennia under the plough and the weight of grazing animals. When the site was revisited in April 2010, one new detail had been added to the record: an ESB electricity pole had been erected at the north-western edge of the monument. It is a quietly deflating footnote, the kind of small, practical intrusion that accumulates around ancient sites so gradually that nobody quite notices until someone writes it down.