Reconstructing the late Pleistocene glacial history of the Cairngorm Mountains, Scotland, using paired cosmogenic 10Be and 14C

Chronologic and geomorphic evidence of past glaciations is largely recorded in areas at relatively low elevation and/or landscapes defined by high glacial erosion. As a result, data from areas that did not experience significant glacial erosion and the highest elevation locations are lacking from reconstructions of past ice masses. Here, we use paired ¹⁰Be and ¹⁴C exposure dating on quartz derived from glacial erratics and bedrock to resolve past ice mass fluctuations across an elevation and geomorphic gradient in the Cairngorm Mountains of Scotland. We find that the highest elevation samples in our dataset, at 1140 m above sea level, yield ¹⁰Be ages indicating 23 000 years of exposure and are at secular equilibrium for ¹⁴C, indicative of a single period of exposure starting as a nunatak during the Last Glacial Maximum. Other samples from above 1000 m elevation produce ¹⁴C exposure ages indicating deglaciation during the Bølling–Allerød Interstadial, while ¹⁰Be concentrations display varying levels of inheritance due to local variations in glacial and non-glacial erosion. Samples from lower elevations indicate a Lateglacial moraine building event 15 000 years ago, coincident with the Wester Ross readvance, followed by a period of glacier retreat interrupted by moraine deposition at ~14 000 and ~11 000 years ago. This dataset reconstructs both thinning and marginal recession of paleo-ice masses within the Cairngorm Mountains across a >600 m vertical gradient during the most recent glacial–interglacial transition, demonstrating the utility of paired ¹⁰Be/¹⁴C exposure dating in ice mass reconstructions in areas of low glacial erosion, increasing the geomorphic diversity of chronologic data available for glacial reconstructions.