At Corlat in County Monaghan, a circular earthwork once occupied a natural col, the low saddle of ground between two higher points, along a broad east-to-west ridge. It is gone now, levelled into ordinary pasture sometime before the 1940s, leaving no trace visible at ground level. What remains is a paper trail: two Ordnance Survey maps, decades apart, each recording the same feature with quiet fidelity before the land swallowed it entirely.

The 1834 edition of the OS six-inch map marked the enclosure in gothic lettering as a "fort", the conventional label applied to the circular earthworks known in Irish as ráth or lios, which were typically built during the early medieval period as enclosed farmsteads or settlement sites. The Corlat example measured roughly 45 metres in external diameter, a fairly typical size for such features. By 1907, the second map still recorded the same circular outline, this time rendered through hachuring, the fine lines surveyors used to suggest raised ground, suggesting the earthen bank was still legible in the landscape at that point. Somewhere in the intervening decades, between that survey and the mid-twentieth century, it was cleared away, most likely during agricultural improvement, a fate that claimed a considerable number of similar earthworks across Ireland during the same period.