Others exist only as photographs, a brief window of visibility caught from the air before the ground closes over them again, or something more permanent arrives. The enclosure at Barnagore, Co. Cork, belongs firmly to the second category. What was once a rectangular earthwork of at least forty metres along its north-west to south-east axis and roughly twenty metres across was visible, briefly, as a cropmark in a single aerial photograph taken in July 1989. Cropmarks form when buried features such as ditches or walls affect how vegetation grows above them, producing patterns readable from altitude but invisible at ground level. That photograph, taken by Dr D.D.C. Pochin Mould, captured three sides of the enclosure; the south-eastern side was already lost, cut off by the townland boundary, with the field beyond it built on.

The enclosure did not survive long after that photograph was taken. During the 1990s, an EMC factory was constructed on the site, covering the remains entirely. What had already been a fragmentary and partially obscured feature was removed from the archaeological record before any excavation could clarify its age, function, or relationship to its immediate surroundings. Immediately to the north lay a bivallate circular enclosure, meaning one defined by two concentric banks and ditches rather than a single circuit, a form associated in Ireland with the early medieval period, though not exclusively so. Whether the rectangular feature and the circular one were contemporary or belonged to different phases of activity at Barnagore is now a question without a physical answer.