A deglaciation model of the Oberhasli, Switzerland

• Published in: Journal of quaternary science Vol. 31; no. 1; pp. 46 - 59
• Main Authors: Wirsig, Christian, Zasadni, Jerzy, Ivy-Ochs, Susan, Christl, Marcus, Kober, Florian, Schlüchter, Christian
• Format: Journal Article
• Language: English
• Published: Chichester Blackwell Publishing Ltd 01-01-2016; Wiley Subscription Services, Inc
• Subjects: 10Be; Age; Alps; Bedrock; Boulders; Deglaciation; deglaciation history; Exposure; exposure dating; Glaciers; Haslital; High Alps; Mathematical models; Switzerland; Switzerland, Alps Mts
• ISSN: 0267-8179; 1099-1417
• DOI: 10.1002/jqs.2831

ABSTRACT
We combine 10Be surface exposure ages from boulders and bedrock, field observations and measurement of bedrock ice‐flow direction indicators with numerical ice surface models to develop a model of the evolution of the Oberhasli area in the central Swiss Alps from the Last Glacial Maximum (LGM) to the early Holocene. Surface exposure ages from bedrock and boulder samples imply that the highest ice surface at the glacial trimline in Haslital was attained at 23.0 ± 0.8 ka. Significant retreat followed no later than 17.7 ± 0.8 ka. Several boulders were let down on the Gelmerhörner ridge during lowering of the ice surface of the Aare LGM glacier. Their exposure ages of 16–14 ka suggest that patches of remnant ice persisted on the trough shoulder until the Bølling–Allerød interstadial. Lateglacial glacier systems in the High Alps were of a dendritic character, confined to the trunk valleys and cirques. Based on combined evidence from glacial erosional marks, surface exposure ages and numerical modelling we have been able to constrain the likely terminal position and ice surface of the Egesen stadial glacier (Younger Dryas equivalent) in Haslital. Exposure ages from the trough floor imply that deglaciation was completed at the end of the Younger Dryas at 12.2–10.8 ka.