Drumlins, the elongated oval hills left behind by retreating glaciers, were frequently chosen as sites for early enclosures across Ulster, and the one at Corratanty carries one such enclosure, though you would need to know what you were looking for to recognise it.

The 1834 edition of the Ordnance Survey six-inch map marks the site plainly, labelling a circular embanked enclosure in gothic lettering as a fort. That cartographic convention, gothic script for antiquities, signals that the surveyors understood they were recording something old rather than a contemporary feature. The enclosure they mapped had an external diameter of around 35 metres, which places it firmly within the range of the ringforts found widely across Ireland, farmstead enclosures typically dating from the early medieval period, roughly 500 to 1000 AD. What survives on the ground today is considerably more modest: a grass-covered interior roughly 17 metres across, defined on the north and east by a curve in the existing field bank, and on the south by traces of a fosse, the shallow external ditch that would have reinforced the enclosing bank. The fosse measures about 3 metres wide at the top, narrowing to 1.4 metres at the base, with an internal height of around one metre. A slight dip in the perimeter at the south-east may mark where the original entrance once stood.