The depression, located in the south-western corner of a ringfort, is thought to mark the roof-fall of a souterrain, one of the stone-lined or dry-built tunnels that early medieval Irish communities constructed beneath their settlements, most likely for cold storage, refuge, or both. The fact that only a sunken outline survives is not unusual; many souterrains across Ireland are known only by the way the ground has quietly given way above them over centuries.

The ringfort to which this souterrain belonged is a separate recorded site in the same townland, and the pairing of the two features would have been entirely typical. Ringforts, the circular enclosed farmsteads that dot the Irish countryside in their thousands, frequently incorporated souterrains as functional annexes, accessible from within the enclosure. The local landscape around Ballinrobe, Lough Mask, and Lough Carra was surveyed in 1994 by D. Lavelle, whose archaeological survey of the district recorded this site, noting at the time that the souterrain was inaccessible and that nothing remained to be examined above ground beyond the depression itself.