Basin-scale patterns of subglacial sediment mobility: Implications for glaciological inversion modelling

Patterns of glacial bedforms and their internal sediments are described from the Omagh Basin, north-central Ireland. Here, drumlins and ribbed moraines were variously formed, preserved and remoulded during several late Devensian ice flow stages, and their patterns can be used as input into glaciological inversion models. More detailed examination of the morphology and internal sediments of these bedforms shows a complex pattern of reworking driven by local-scale basal thermal and hydrological regime. Sediment lithofacies associations and patterns of erratic carriage can be used to better evaluate ice–bed conditions and basal processes than bedforms alone. The sedimentary evidence suggests that bedforms were unlikely to have been formed during a single glacial episode, as is implicit in glaciological inversion models, and more likely formed during several episodes that cannot be resolved by crosscutting or superimposed bedform relationships alone.