Problems of Irish drumlins and Late Devensian ice sheet reconstructions

Abstract

Reconstructions of the Late Devensian ice sheet in Ireland are strongly biased towards explaining data obtained by the Geological Survey of Ireland during the last century, and observations undertaken by key workers in this century (i.e. J. K. Charlesworth). Modern field observation and analytical techniques, however, show that many of these data, such as the distribution of drumlins, are erroneous. Furthermore, models derived from these data, dealing with the significance and distribution of different bedform types, the location of ice centres and the direction of ice flow lines, can no longer be supported. New observations based on mapping from satellite imagery, and validated by detailed regional-scale field studies, show the complexity of subglacial bedform patterns which record several phases of subglacial activity during the Late Devensian. The presence of ice flow-transverse Rogen moraines and patterns of overprinted bedforms in north central Ireland suggest that subglacial environments and the location of ice centres changed dramatically during the overall glacial cycle.