That, in a way, is exactly what makes this spot interesting. A circular earthwork once visible here has been entirely levelled, leaving no surface trace, yet its brief appearance on the 1837 edition of the Ordnance Survey six-inch map has kept it lodged in the archaeological record ever since.

The earthwork's true nature remains genuinely uncertain. A mound barrow, the kind of low, rounded funerary mound raised over burials during prehistoric periods, sits around 110 metres to the south and was recorded in a similar fashion on the same map sheet. The resemblance between the two features has led some researchers to suggest that this northern earthwork may originally have been a barrow of the same type. The 1837 map, however, did not mark it as an antiquity, which hints that even at the time of surveying it was not obviously ancient. A competing interpretation holds that both features could be landscaped tree-rings, ornamental circular plantings laid out after 1700 as part of the designed grounds associated with Rock Brook House. Tree-rings of that kind were a fairly common element of eighteenth and nineteenth-century demesne landscaping in Ireland, used to frame views or punctuate parkland. Whether this earthwork began its life as a burial monument later absorbed into a designed landscape, or was always simply a landscaping feature that happened to resemble something older, is a question the ground itself can no longer answer.