Lateglacial (Younger Dryas) glaciers and ice-sheet deglaciation in the Cairngorm Mountains, Scotland: glacier reconstructions and their palaeoclimatic implications

• Main Author: Matthew R. Standell
• Format: Thesis
• Language: unknown
• Published: 2014
• Subjects: Earth Sciences not elsewhere classified; Glacial geomorphology; Palaeoclimate; Cairngorm Mountains; Scotland; Younger Dryas; Glacier reconstruction; Equilibrium-line altitude; Cosmogenic 10Be surface exposure dating; Topoclimatic factor; Snow blow; Dryas Glacier; Ice Sheet
• Online Access: https://figshare.com/articles/thesis/Lateglacial_Younger_Dryas_glaciers_and_ice-sheet_deglaciation_in_the_Cairngorm_Mountains_Scotland_glacier_reconstructions_and_their_palaeoclimatic_implications/9487499

The Cairngorm Mountains contain an outstanding assemblage of glacial landforms from both the deglaciation of the last British Irish Ice Sheet and the Younger Dryas readvance. Glaciers are recognised as sensitive indicators of past and present climate change and, thus, these landforms provide information about past climate and glacier-climate interaction that can be used to contextualise the present climate change. Previous interpretations have left doubt over the extent and style of the Younger Dryas readvance. In addition, the pattern and timing of deglaciation in the southern Cairngorms and, particularly, how local and external ice masses interacted is unclear. New geomorphological mapping from aerial images and fieldwork has been compiled in a GIS for a 600km2 area of the Cairngorm Mountains. This has allowed a complex pattern of ice-dammed lakes and local and regionally sourced ice margins to be reconstructed during the retreat of the last British Irish Ice Sheet. The mapping has been combined with new cosmogenic surface exposure ages taken from areas of hummocky moraine previously subject to differing age interpretations. The effect of moraine denudation on apparent 10Be ages has been checked by inverse modelling of the 10Be concentration vs. boulder height. The results indicate more extensive Younger Dryas glaciation, with glacier reconstructions and equilibrium-line altitudes (ELAs) comparable with the surrounding areas. Reconstruction of both valley and plateau-fed glaciers are presented, with modelling of local topoclimatic factors, such as radiation, avalanche and snow drifting, combined with precipitation gradients, explaining most of the variation within the glacier ELAs. The geomorphological evidence and palaeoclimatic inferences are important, alongside a growing number of palaeoglaciological studies, in acting as evaluation areas for current numerical models of ice-sheet growth and decay.