The Bardahessiagh Formation is a geological formation in Northern Ireland. It has been described from a locality lying about 3 km NNE of Pomeroy, south of Craigbardahessiagh. It is now known as comprising the former ‘Bardahessiagh Formation’, or Bardahessiagh Beds and the ‘Junction Beds’ that is underlain by a stratigraphical unit not recognised, until fieldwork by the Ulster Museum staff in 1992. The Bardahessiagh Formation is divided into three units, but the summit of the formation is not known. Field evidence indicates that the local top of the formation is characterised by a thrust contact with the Killey Bridge and Tirnaskea Formation, exposed south of the Well Field, which lies 650 metres SSW of Craigbardahessiagh.