What the Ordnance Survey cartographers recorded in 1838 as a circular tree plantation, roughly thirty metres across on a gentle south-facing slope, had already begun to resist easy interpretation by the time later mapmakers returned to it. By the 1921 edition of the OS six-inch map, the neat circle of trees had been replaced by a curving line of hachures, the small hatched marks surveyors used to suggest a rise or bank in the terrain, running from the south-south-east around to the west. Today, no visible surface trace survives at all.

What that progression of cartographic details might represent is genuinely uncertain. The circular form noted in 1838 could have been a deliberate planting around an existing earthwork, a not uncommon practice on Irish estates where ring forts or enclosures were incorporated into demesne landscaping and sometimes planted over or ornamented. The hachures on the later map hint that something low and curved did exist in the ground at some point, possibly the remnant bank of an enclosure, which in Irish archaeology typically refers to a defined area bounded by an earthen bank and ditch, used variously for settlement, agriculture, or ceremonial purposes across a very long span of prehistory and the early medieval period. Whether the feature at Tullira was any of these things, or simply a landscape curiosity shaped by planting and later erosion, remains an open question.