By the time the Ordnance Survey mapped the area in 1838, it was recorded simply as a tree-covered enclosure standing to the east of the main avenue leading up to the house. Whether it began as an ancient ringfort or was constructed purely as a landscape feature is a question that remains genuinely open.

A ringfort, to use the term loosely, is typically an early medieval enclosed settlement defined by one or more earthen banks and ditches, used in Ireland from roughly the fifth to the twelfth centuries. The earthwork at Clonyn fits that basic physical description: a roughly circular area of about 29 metres across, bounded by an earthen bank and a shallow external fosse, or ditch, with what may be an original entrance gap on the west-south-west side. Deep cultivation ridges running east to west are still visible across the interior, suggesting the ground was worked at some point, though whether before or after any landscaping is unclear. Two further enclosures lie within 110 metres, one 45 metres to the south-west and another 110 metres to the west, raising the possibility that all three were either pre-existing ringforts absorbed into the designed landscape of Clonyn House demesne, or earthworks deliberately constructed as tree-rings in the post-1700 period as part of that same ornamental scheme. Landowners of the Georgian era frequently incorporated or mimicked ancient earthworks within their demesnes, using circular tree plantings to add a sense of antiquity and drama to otherwise managed parkland. The difficulty here is that the physical evidence does not settle the matter either way.