The Donegal ice dome, northwest Ireland: dimensions and chronology

Geomorphological evidence indicates that Donegal was formerly occupied by an ice dome that extended offshore to the west, northwest and north and was confluent with adjacent ice masses to the east and south. Erosive warm-based ice over-rode almost all the highest mountains, implying an ice-divide altitude greater than 700m. Only six peripheral summits escaped glacial modification, implying either that they remained above the ice surface as nunataks or supported a thin cover of protective cold-based ice. Gibbsite, a pre-last glacial weathering product, is preferentially represented on summits that escaped glacial modification. Cosmogenic Be-10 exposure ages of 18.6 +/- 11.4 to 15.9 +/- 1.0 k yr for coastal sites confirm that Donegal ice extended offshore at the last glacial maximum. Reconstruction of the form of the Donegal ice dome suggests a former minimum ice thickness of similar to 500 m close to the present coastline in the west and northwest, and similar to 400 m near the coast of the Inishowen Peninsula in the north, with the ice extending at least 20 km across the adjacent shelf to the west and northwest. Copyright (C) 2007 John Wiley & Sons, Ltd.