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

LALLY, Amy, RUFFELL, Alastair, NEWTON, Andrew M. W., REA, Brice R., KAHLERT, Thorsten, STORRAR, Robert, SPAGNOLO, Matteo, GRAHAM, Conor and COLEMAN, Millie (2023). The evolution and preservation potential of englacial eskers: An example from Breiðamerkurjökull, SE Iceland. Earth Surface Processes and Landforms.

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Abstract

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.

Item Type:	Article
Additional Information:	** Article version: VoR ** From Wiley via Jisc Publications Router ** Licence for VoR version of this article: http://creativecommons.org/licenses/by/4.0/ **Journal IDs: issn 0197-9337; issn 1096-9837 **Article IDs: publisher-id: esp5664 **History: published_online 17-07-2023; accepted 30-06-2023; rev-recd 22-06-2023; submitted 27-04-2023
Uncontrolled Keywords:	glacial geomorphology, landform evolution, UAV, glacial process‐form regimes, englacial glacial drainage system, esker, temperate glacier, Iceland, GPR
Identification Number:	https://doi.org/10.1002/esp.5664
SWORD Depositor:	Colin Knott
Depositing User:	Colin Knott
Date Deposited:	17 Jul 2023 10:05
Last Modified:	17 Jul 2023 10:05
URI:	https://shura.shu.ac.uk/id/eprint/32146

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