Glaciation of Scotland during the Younger Dryas stadial: a review

Considerable research effort in recent years has refined our knowledge of the landforms and sedimentary sequences generated by glaciers of the last cold episode in Scotland, the Younger Dryas, and the chronology of their formation. These recent advances have benefited from new technologies such as high-resolution digital terrain models, numerical ice sheet simulations and cosmic ray surface exposure dating. This review presents a summary of recent Younger Dryas research in Scotland, particularly focusing on studies from the last two decades. The findings of these investigations are compared with those of earlier workers and, critically, are appraised in terms of their relevance to five key aspects of Younger Dryas glaciation: growth of the ice cap, its geometry, dynamics, mode of decay and likely stadial climate. Minor differences aside, the consensus view appears to favour a relatively thick but areally restricted central ice cap surrounded by satellite ice fields. At its centre, the ice cap was probably thickest during the first 500 years of the stadial, after which it most likely thinned as the climate became increasingly arid. Outlet glaciers were dynamic only in marginal areas, where they produced abundant moraine sequences during deglaciation, but throughout much of the stadial central areas of the ice cap effected only minimal landscape modification. Deglaciation took place by active retreat under a rapidly warming climate. Overall, the stadial was dominated by much colder and drier conditions than present, and probably experienced greater intra-annual temperature ranges. Copyright (C) 2009 John Wiley & Sons, Ltd.