The first edition of the Ordnance Survey map records a circular enclosure at this spot, the kind of roughly circular earthwork, often called a ringfort or rath, that was once used across Ireland as an enclosed farmstead or homestead, typically in the early medieval period. But nothing of it remains above ground today, and anyone standing on that gentle rise would see no trace of what the mapmakers once recorded.

By the time the second edition of the OS map was produced, the enclosure was already being swallowed by the working landscape. The later map shows it bisected by a field boundary, suggesting that agricultural reorganisation had cut straight through the site, redistributing the earth and erasing whatever bank or ditch had once defined its perimeter. The process is not unusual. Thousands of similar enclosures across Ireland were levelled during the eighteenth and nineteenth centuries as land was enclosed, drained, and divided more intensively. What makes Rossacoosane quietly notable is simply that the cartographic record caught the enclosure at two distinct moments, once whole and once already being divided, before it disappeared from the ground entirely. A. O'Sullivan and J. Sheehan documented what remained of the record in their 1996 archaeological survey of the Iveragh Peninsula, published by Cork University Press, though by then the physical evidence had long since gone.