It is roughly sub-circular, measuring about nine metres east to west and seven metres north to south, ringed by a well-preserved earthen bank and a steep external fosse, which is the term for a ditch cut to define or defend an enclosure. The interior slopes gently downward from west to east. At that scale, and with that level of preservation, it would be easy to assume some early medieval origin. The evidence, however, points elsewhere.

The site sits within the landscaped grounds of Killua Castle, roughly 545 metres to the north-west of the castle itself. The Ordnance Survey six-inch map of 1837 records no antiquity at this location, which is a meaningful absence. When the OS mapped Ireland in that period, their surveyors were generally attentive to earthworks of any obvious age. The most plausible interpretation is that this is a tree-ring, a deliberate landscape feature of post-1700 date. Tree-rings were constructed in demesne gardens and designed landscapes of the eighteenth and early nineteenth centuries, typically as circular or near-circular earthen platforms or enclosures planted with a single specimen tree or a small formal group. They were ornamental rather than defensive, part of the picturesque vocabulary that estate owners applied to their grounds during that period. The bank and fosse here would have framed the planting, given it visual presence on the hillside, and marked it as an intentional composition within the wider landscape rather than an accident of nature or agriculture.