On the 1948 revision of the Ordnance Survey six-inch map, it appeared as a hachured feature, the small radiating lines cartographers use to suggest a depression or raised earthwork in the landscape. That notation implied something worth marking, something with a shape deliberate enough to record. When the site was actually inspected in 1983, the feature turned out to be an overgrown hollow, its origins ambiguous enough that surveyors could only conclude it was possibly natural but more likely a disused quarry pit.

The distinction matters more than it might seem. Because the hollow is judged to be of post-AD 1700 date, it falls outside the remit of formal archaeological classification in Ireland, which generally concerns itself with features from earlier periods. That boundary places the Cloonoon hollow in a quiet administrative no-man's-land: too recent to be ancient, too ambiguous to be firmly identified, and too overgrown to give much away. Quarry pits of this kind were once common features of the rural Irish landscape, dug to extract limestone, gravel, or other local stone for building walls, roads, and farmsteads. Most were small, localised operations that left no written record, only a scar in the ground that grass eventually reclaimed.