1 A Younger Dryas plateau icefield in the Monadhliath, Scotland, and 2 implications for regional palaeoclimate 3 4 5 Clare M. Bostona, b*, Sven Lukasa, and Simon J. Carra 6 7 aSchool of Geography, Queen Mary University of London, Mile End Road, London, E1 4NS, UK 8 bDepartment of Geography, University of Portsmouth, Buckingham Building, Lion Terrace, 9 Portsmouth, PO1 3HE, UK 10 11 *Corresponding Author:
[email protected], 023 92 842498 12 13 14 Abstract 15 A record of Younger Dryas glaciation in Scotland is well established. However, the role of 16 the Monadhliath, a significant plateau area extending over 840 km2 in central Scotland, has 17 never been investigated systematically. We present the first systematic glacial 18 geomorphological mapping across the whole region, which has led to the identification of 19 hitherto-unrecorded glacial and associated landforms. The spatial distribution of these 20 landforms indicates that the last phase of glaciation in the area was that of a local plateau 21 icefield. In addition, a clear morphostratigraphical signature provides a strong indication that 22 the icefield dates to the Younger Dryas (12.9-11.7 ka), which is supported by numerical ages 23 in the southeast of the study area. Based on the geomorphological evidence and 2D glacier 24 surface profile modelling, a 280 km2 icefield is reconstructed. A novel approach is introduced 25 to quantify plateau icefield thickness for equilibrium line altitude (ELA) and 1 1 palaeoprecipitation calculations, resulting in greater overall data confidence compared to 2 traditional reconstruction methods. The ELA for the whole icefield is calculated to be 714 ± 3 25 m, whilst the ELAs of individual outlet glaciers range from 560 m in the west to 816 m in 4 the east, demonstrating a significant W-E precipitation gradient across the region during the 5 Younger Dryas.