The evolution and preservation potential of englacial eskers: an example from Breiðamerkurjökull, SE Iceland

Amy Lally*, Alastair Ruffell, Andrew M. W. Newton, Brice R. Rea, Thorsten Kahlert, Robert D. Storrar, Matteo Spagnolo, Conor Graham, Millie Coleman

*Corresponding author for this work

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Directly observing glacial drainage systems (englacial and subglacial) is challenging. The distribution, morphology and internal structure of eskers can provide valuable information about the glacial drainage system and meltwater processes. This work presents the annual evolution (meltout) and internal structure of an esker emerging from the Breiðamerkurjökull ice margin, southeast Iceland. Changes in esker morphology have been repeatedly mapped over a 1-year period using high temporal and spatial resolution data acquired by an uncrewed aerial vehicle (UAV). The internal architecture of the esker was investigated using ground-penetrating radar (GPR) surveys. These data are used to identify the dominant processes driving the formation of this englacial esker and to evaluate the preservation potential. The englacial esker was up to 2.6 m thick and ice-cored. A large moulin upglacier of the esker, which evolved into an englacial conduit, supplied meltwater to the englacial channel. Upglacier dipping debris-filled basal hydrofractures, formed by pressurised subglacial meltwater rising up the retrograde bed slope, likely supplied sediment to the englacial conduit. Over the 1-year period of observation the crest morphology evolved from flat- to sharp-crested and the esker footprint increased by a factor of 5.7 in response to post-depositional processes. The findings presented here indicate that englacial eskers may have low preservation potential due to post-depositional reworking such as slumping through ice-core meltout and erosion by later meltwater flow. As englacial eskers may not be preserved in the landscape, they could represent important glacial drainage system components that are not currently captured in palaeo-ice sheet reconstructions. This work highlights the value of creating a time series of high-temporal resolution data to quantify morphological evolution and improve glacial process-form models.

Original languageEnglish
Number of pages20
JournalEarth Surface Processes and Landforms
Early online date17 Jul 2023
Publication statusEarly online date - 17 Jul 2023

Bibliographical note

Funding Information:
AL was funded by UKRI QUADRAT Doctoral Training Programme (DTP) studentship (NE/S007377/1) and the Soulby Research Fund (QUB). AMWN would like to thank the British Society for Geomorphology Early Career Researcher fund. RDS received funding from the Quaternary Research Association. We wish to thank David Evans and one anonymous reviewer for their valuable input and detailed suggestions, which improved the final manuscript. We are especially grateful to Sigurður Óskar Jónsson of Vatnajökull National Park for supplying our research permits. We would also like to thank Haukur Ingi Einarsson of Glacier Adventure for helping with equipment postage and storage. Aerial photographs (1951‐2007) were obtained from Landmælingar Islands and NERC ARSF.

Publisher Copyright:
© 2023 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.


  • englacial glacial drainage system
  • esker
  • glacial geomorphology
  • glacial process-form regimes
  • GPR
  • Iceland
  • landform evolution
  • temperate glacier
  • UAV

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Earth-Surface Processes
  • Earth and Planetary Sciences (miscellaneous)


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