26 Apr 2023
 | 26 Apr 2023
Status: this preprint is currently under review for the journal ESurf.

Ice buttressing-controlled rock slope failure on a cirque headwall, English Lake District

Paul Anthony Carling, John Duncan Jansen, Teng Su, Jane Lund Andersen, and Mads Faurschou Knudsen

Abstract. Rock slope failures in the English Lake District have been associated with deglacial processes after the Last Glacial Maximum, but controls and timing of failures remain poorly known. A cirque headwall failure was investigated to determine failure mechanisms and timing. The translated wedge of rock is thin and lies on a steep failure plane, yet the friable strata were not disrupted by downslope movement. Fault lines and a failure surface, defining the wedge, were used as input to a numerical model of rock wedge stability. Various failure scenarios indicated that the slope would have failed catastrophically, if not supported by glacial ice in the base of the cirque. The amount of ice required to buttress the slope is insubstantial, indicating likely failure during thinning of the cirque glacier. We propose that, as the ice thinned, the wedge was lowered slowly down the cirque headwall gradually exposing the failure plane. A cosmogenic 10Be surface exposure age of 18.0 ± 1.2 ka from the outer surface of the wedge indicates Late Devensian de-icing of the back wall of the cirque, with a second exposure age from the upper portion of the failure plane yielding 12.0 ± 0.8 ka. The 18.0 ± 1.2 ka date is consistent with a small buttressing ice mass being present in the cirque at the time of regional deglaciation. The exposure age of 12.0 ± 0.8 ka represents a minimum age, as the highly-fractured surface of the failure plane has experienced post-failure mass-wasting. Considering the dates, it appears unlikely that the cirque was re-occupied by a substantial ice mass during the Younger Dryas Stadial.

Paul Anthony Carling et al.

Status: open (until 29 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Paul Anthony Carling et al.

Paul Anthony Carling et al.


Total article views: 192 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
146 39 7 192 19 5 5
  • HTML: 146
  • PDF: 39
  • XML: 7
  • Total: 192
  • Supplement: 19
  • BibTeX: 5
  • EndNote: 5
Views and downloads (calculated since 26 Apr 2023)
Cumulative views and downloads (calculated since 26 Apr 2023)

Viewed (geographical distribution)

Total article views: 177 (including HTML, PDF, and XML) Thereof 177 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 29 May 2023
Short summary
Many steep glaciated rock-walls collapsed when the Ice Age ended. How ice supports a steep rock-wall until the ice decays is poorly understood. A collapsed rock-wall was surveyed in the field and numerically modelled. Cosmogenic exposure-dates show the rock-wall collapsed and became ice-free c. 18 ka ago. The model showed that the rock-wall failed very slowly because ice was buttressing the slope. Dating other collapsed rock-walls will improve understanding of how and when the last Ice Age ended.