The ground dips a little, the grass grows a little differently, and unless you know what you are looking for, the whole thing reads as nothing more than a quirk of drainage. But this oval earthwork in the townland of Crean, in the Smallcounty Barony, is something older and considerably more elusive: a site that does not appear on any edition of the Ordnance Survey Ireland historic maps, and whose existence only came to light through aerial photography.

The earthwork, recorded as Site No. 031187, was first identified from a Bórd Gáis Éireann 1:5,000 aerial photograph taken on 3 November 1984. What the photograph revealed was a circular-shaped feature that ground-level survey has since refined into a slightly sunken oval, measuring roughly 14 metres north-northwest to south-southeast and 8 metres east-northeast to west-southwest. It is defined by the remnants of a scarp, about 4.5 metres wide and less than half a metre high, with a possible outer fosse, a shallow ditch-like feature, visible only along the northern and western sides, though this may simply be a drainage channel. Around 180 metres to the south-west and south lie a ring-barrow and a separate enclosure annotated on records as Lisduffnacrean, and about 345 metres to the west there is a possible medieval road, suggesting this corner of Limerick carries considerable accumulated activity across different periods. A field boundary that once ran to the south of the earthwork, visible on the Ordnance Survey 25-inch map, has since been removed as part of modern land improvement works, and further earthworks and drainage channels visible in the 1984 aerial photographs had already disappeared from Google Earth imagery captured in June 2018 and September 2020. The site was compiled by Fiona Rooney and uploaded to the record in March 2021.

The site sits in reclaimed pasture, which means the surrounding land has been actively managed and altered over time, making any surviving earthwork features all the more fragile. For anyone wanting to observe what remains, the scarp is subtle enough that low, raking light, early morning or late afternoon, will help pick out the slight change in ground level. The northern and western arc is where the possible fosse trace is most legible. There is no formal access or signage, and the site is on agricultural land, so permission from the landowner would be the appropriate first step before visiting.