Evidence for rapid paraglacial formation of rock glaciers in southern Norway from 10 Be surface-exposure dating

• Published in: Quaternary Research
• Main Authors: Linge, Henriette, Nesje, Atle, Matthews, John A., Fabel, Derek, Xu, Sheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2020
• Subjects: Norway; Øyberget; glacier; Ice; permafrost
• Online Access: http://dx.doi.org/10.1017/qua.2020.10; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589420000101

Abstract We evaluate the timing and environmental controls on past rock-glacier activity at Øyberget, upper Ottadalen, southern Norway, using in situ 10 Be surface-exposure dating on (1) boulders belonging to relict rock-glacier lobes at c. 530 m asl, (2) bedrock and boulder surfaces at the Øyberget summit (c. 1200 m asl), and (3) bedrock at an up-valley site (c. 615 m asl). We find that the rock-glacier lobes became inactive around 11.1 ± 1.2 ka, coeval with the timing of summit deglaciation (11.2 ± 0.7 ka). This is slightly older than previously published Schmidt-hammer surface-exposure ages. The timing does not match known climatic conditions promoting rock-glacier formation in the early Holocene; hence we infer that lobe formation resulted from enhanced debris supply and burial of residual ice during and soon after deglaciation. The results demonstrate that rock glaciers may form over a relatively short period of time (hundreds rather than thousands of years) under non-permafrost conditions and possibly indicate a paraglacial type of process.