Abstract

The Killard Point moraine formed when Late Pleistocene ice grounded on the isostatically depressed coastal lowlands of County Down, Northern Ireland, at a time of relatively high sea level. The moraine consists of three major lithologic associations which prograded for about 1 km from the ice-grounding zone into a glaciomarine environment. At the base of the succession a diamicton association is characterized by massive and stratified diamictons that are mainly debris flows. It contains a minor ice-rafted debris component. The overlying sand association was deposited from sediment-gravity flows of low to intermediate viscosity. The gravel association was deposited by high-density sediment-gravity flows. Massive mud beds or drapes occur throughout the sequence and are related to low-density turbidity or contour currents. Sequences of this type are more common in the geological record than the literature suggests and are often explained in terms of terrestrial-based deglacial models. This calls for a sedimentological reappraisal of many "glacigenic" deposits which accumulated in areas subject to deep isostatic depression during the Late Pleistocene.

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