Cosmogenic (10Be) surface-exposure ages from the Burtness Comb rock avalanche, Lake District, northwest England

Peter Wilson, David Jarman, Maria Miguens-Rodriguez, Derek Fabel

    Research output: Contribution to journalArticlepeer-review


    The age of the lower component of the Burtness Comb rock avalanche debris tongue, Lake District, northwest England, has been determined by in situ produced terrestrial cosmogenic (10Be) surface-exposure dating of quartz veins from three boulders. Uncertainty-weighted mean ages of 17.37 ± 0.94 ka (determined using the Loch Lomond calibration dataset) and 16.08 ± 1.25 ka (determined using the CRONUS-Earth default calibration dataset) indicate that this component of the rock avalanche occurred during deglaciation following the local Last Glacial Maximum. The surface morphology displayed by the debris indicates it likely accumulated on glacier-free terrain, suggesting that the Burtness Comb cirque glacier had decoupled from the Buttermere valley glacier at the time of debris emplacement. The debris may have travelled across the surface of a waning glacier in the upper part of the cirque. Although the upper component of the rock avalanche is as yet undated its position and configuration indicate it to be younger than the lower component and sourced from a different part of the comb headwall. The rock avalanche is only the third of 84 rock slope failures recognised in the Lake District and adjacent Howgill Fells to have been dated using 10Be. Whilst the rock avalanche is regarded as a paraglacial landform, additional ages on other members of this population are required in order to establish their temporal pattern and to propose the most probable underlying cause(s) of failure.
    Original languageEnglish
    Pages (from-to)619-626
    Number of pages8
    JournalProceedings of the Geologists' Association
    Issue number5-6
    Early online date28 Sept 2023
    Publication statusPublished (in print/issue) - 31 Oct 2023

    Bibliographical note

    Funding Information:
    We thank Professor Stefan Winkler (University of Wuerzburg) for discussing the decoupling of cirque glaciers from valley glaciers in an alpine setting. Supportive reviews from Dr Ian S. Evans and Professor John A. Matthews helped us sharpen the manuscript. The figures were prepared by Anna Ratcliffe.

    Publisher Copyright:
    © 2023 The Geologists' Association


    • rock avalanche
    • Cosmogenic (10Be) surface exposure dating
    • Deglaciation
    • Paraglacial
    • Lake District
    • Rock avalanche
    • Cosmogenic ( Be) surface-exposure dating


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