The Western Mournes Lowlands are characterised by drumlins with numerous poorly-aligned hummocks and enclosed depressions on their lower slopes and in intervening lows. Drumlins have a consistent long axis orientation towards the southeast. Long axes are 500-800m and short axes are 300-500m in length. Morphology is generally of the classic type although long profiles are frequently slightly undulating. A drumlin at Ballyrussell [J151 215) is slightly arcuate. An exposure in the lower central slopes of a drumlin at Drumesk [J167 193] contains vaguely stratified sandy gravel and massive diamict. Drumlins are evidence of fast ice flow which streamlined the deformable, water-laden sediment substrate and may have resulted from marine downdraw by the Carlingford ice-stream.
Inter-drumlin hummocks are low (<5m high), rounded to oval in plan, closely spaced, occasionally connected and are generally non-aligned. They are frequently separated by small enclosed depressions. These are kettleholes and vary from 0.2ha to 2.5ha in size. An exposure in a hummock on the flank of a drumlin [J143 216] consists of chaotic, poorly-sorted and mainly angular to subangular pebbles to small boulders in a coarse sand matrix. The spatial organisation and internal structure of hummocks is consistent with inverted disintegration topography at a stagnant ice margin.
