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Lateglacial and early Holocene dynamics of adjacent valley glaciers in the Western Swiss Alps



The Alps play a pivotal role for glacier and climate reconstructions within Europe. Detailed glacial chronologies provide important insights into mechanisms of glaciation and climate change. We present 26 10Be exposure dates of glacially transported boulders situated on moraines and ice-moulded bedrock samples at the Belalp cirque and the Great Aletsch valley, Switzerland. Weighted mean ages of ∼10.9, 11.1, 11.0 and 9.6 ka for the Belalp, on up to six individual moraine ridges, constrain these moraines to the Egesen, Kartell and Schams stadials during Lateglacial to early Holocene times. The weighted mean age of ∼12.5 ka for the right-lateral moraine of the Great Aletsch correlates with the Egesen stadial related to the Younger Dryas cooling. These data indicate that during the early Holocene between ∼11.7 and ∼9.2 ka, glaciers in the Swiss Alps seem to have been significantly affected by cold climatic conditions initiated during the Younger Dryas and the Preboreal Oscillation. These conditions resulted in glacier margin oscillations relating to climatic fluctuations during the second phase of the Younger Dryas – and continuing into Boreal times – as supported by correlation of the innermost moraine of the Belalp Cirque to the Schams (early) Holocene stage. Copyright © 2011 John Wiley & Sons, Ltd.