A cairn, in the Irish archaeological context, is a mound of heaped stones, typically prehistoric in origin, often associated with burial or memorial practices, and this one measures roughly 17.5 metres north to south and 18.5 metres east to west, rising to about one and a half metres at its highest point. The eastern side has been disturbed at some point, though by what or whom is not recorded.

What makes this particular site quietly curious is its cartographic history. The hill itself, named Corran on both the 1842 and 1905 Ordnance Survey six-inch maps, appears without any indication of the cairn at all, as though the mound either escaped notice or was not considered significant enough to mark. It is only on the 1935 OS six-inch map that the cairn finally appears, rendered as a roughly circular area of about twenty metres in diameter, defined by a ring of dots and with a triangulation point at its centre. That triangulation point suggests the mound's elevation made it useful for surveying purposes, which may well be how it finally entered the cartographic record after nearly a century of omission.