干旱区生态环境知识资源中心

A significant inventory of evidence exists for Loch Lomond Stadial (LLS; approximate to Younger Dryas) glaciation in Scotland, with recent work focused on satellite icefields. However, studies of more marginal settings are important for assessing the influence of topoclimatic factors on glacier functioning and, crucially, the impact of these on glacier-derived palaeoclimatic reconstructions. We present systematic assessments of snowblow and avalanching contributions, informed by modern analogues, and test these using the first detailed palaeoglaciological reconstructions of three corrie glaciers on Ben More Coigach, north-west Scotland. Based on morphostratigraphic principles, and lithostratigraphic evidence from the region, these have been attributed to the LLS, with the reconstructions yielding an average equilibrium-line altitude (ELA) of 328 +/- 16m. A glacier-derived sea-level equivalent precipitation value of 1903 +/- 178mm a(-1) is inferred for the LLS, suggesting wetter conditions than currently and contradicting assertions of a more arid LLS climate. Comparison with published palaeoprecipitation estimates indicates Ben More Coigach does not conform to expected regional precipitation gradients. We argue that these discrepancies reflect topographically enhanced snow accumulation, which lowered the ELA from the true’ climatic ELA. This highlights the importance of assessing the influence of topoclimatic factors when applying small glaciers in palaeoclimatic reconstructions.