Lateglacial surface exposure dating in the Monadhliath Mountains, Central Highlands, Scotland

Abstract

We constrain the deglaciation history of the Monadhliath Mountains since the Last Glacial Maximum using glacial geomorphology and surface exposure dating. Collectively these data clarify the glacial history of the Monadhliath Mountains at the close of the Devensian cold period. 10Be exposure ages indicate deglaciation of the Last Devensian ice sheet at 15.1 ± 1.4 ka at ca 640 m OD. The exposure ages are consistent with basal radiocarbon ages from nearby Loch Etteridge, 5 km to the south-east (15.3 ± 0.2 kcal BP11ka is used for ages in this study, kcal BP for calibrated ages and 14C kyrs BP for uncalibrated ages 1.). Boulders from moraines in three Monadhliath corries yielded exposure ages between 11.8 ka and 9.8 ka (470–600 m OD), suggesting that a Lateglacial advance occurred during the Younger Dryas stadial. The limited extent of these Younger Dryas glaciers in the Monadhliath Mountains results from the combined effect of a drier climate experienced in the eastern part of the Central Highlands ice cap and topographical factors. Our reconstruction largely supports the deglaciation model of Golledge et al. (2008) and confirms that a SW to NE precipitation gradient dominated Scotland during the Younger Dryas.