Reconstruction and palaeoclimatic implications of Loch Lomond Readvance glaciers in the Southeast Grampians, Scotland

Abstract

The glaciation of Scotland during the Loch Lomond Stadial (LLS; 12.9–11.7 ka BP) left a distinct and well-preserved geomorphological signature, permitting detailed reconstructions of former glaciers and palaeoclimatic conditions. However, the extent and style of glaciation in the Southeast Grampians remains poorly constrained. This study employs geomorphological mapping and glacier surface profile modelling to reconstruct a ∼60 km² icefield covering much of the Mounth Plateau. The results suggest that plateau ice was thicker and more extensive than previously considered, with a polythermal regime inferred from the geomorphological evidence. Based on contrasting landform assemblages inside and outside of reconstructed glacial limits and basal radiocarbon dates, the icefield is attributed to the LLS. The geomorphological evidence and superimposed streamlining of recessional moraines within the study site suggest that deglaciation was active and interrupted by periods of re-advance occurring during fluctuating climatic conditions. An equilibrium line altitude of 738 m and a precipitation value at sea level of 845 ± 150 mm a⁻¹ are calculated for the Mounth Icefield, suggesting a slightly more arid climate than present. Comparison with published glacier-derived palaeoclimatic variables supports a strong west–east precipitation gradient across Scotland during the LLS.