The interaction of a surging glacier with a seasonally frozen foreland: Hagafellsjökull-Eystri, Iceland
Matthew R. Bennett, David Huddart, Richard I. Waller, 2005. "The interaction of a surging glacier with a seasonally frozen foreland: Hagafellsjökull-Eystri, Iceland", Cryospheric Systems: Glaciers and Permafrost, C. Harris, J. B. Murton
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This paper describes aspects of the landform-sediment assemblage produced by a recent surge of Hagafellsjökull-Eystri. This surge occurred during the winter and early spring of 1998/1999 and consequently advanced into a partially frozen foreland. Two aspects of this landform-sediment assemblage are considered. First the evidence for a frozen subglacial sediment layer beneath a lateral piedmont lobe formed during the surge is reviewed. This sediment layer consists of blocks of glacier ice set within a matrix of frozen sediment and was injected into basal crevasses to form a network of crevasse-squeeze ridges prior to freezing. The sediment layer appears to provide evidence of sub-freezing deformation at the termination of the surge. Secondly the paper examines the detailed tectonic facies within a push-moraine formed along the eastern latero-frontal margin of the glacier during the surge. Architecturally this push moraine consists of a multi-layered slab of glaciofluvial sediments with a monocline structure that has been displaced laterally by the advancing ice margin. The sediment slabs within this monocline are characterized by both brittle and ductile styles of deformation. The authors argue that the observed variation in deformation style may be explained by spatial variation in the extent to which the glacial foreland was frozen or unfrozen at the time of displacement. Areas of frozen foreland would have behaved in a brittle fashion, while unfrozen areas deformed in a more ductile manor. Both these aspects of the landform-sediment assemblage examined in this paper appear to be the product of the seasonal timing of the surge. Not only do they add to our understanding of surge-type landsystems, but they also illustrate the potential of winter advances around the margins of some temperate glaciers to explore the coupling between glaciers and frozen proglacial sediments.
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The introduction of the term periglacial by Łoziński in 1909 to describe the cold-climate conditions in the zone adjacent to, but beyond, the Pleistocene glaciers encouraged the separate development of geocryological and glaciological research. Geological and geomorphological processes at the interface between glaciers and permafrost have, as a result, been given less attention than they warrant, and the influence of one on the other has in many respects been neglected. This book includes a collection of papers that emphasize glacier-permafrost interactions. Papers consider permafrost and its influence on glacitectonic processes, glacial meltwater systems and ground-ice development in proglacial and ice-marginal environments. In addition, recent research findings are reported on paraglacial processes, permafrost evolution, rock glaciers, the formation of ice-wedge casts and periglacial slope evolution. It is hoped that this book will stimulate interest in the interface between glacial and periglacial systems, and encourage further collaborative research involving glaciologists and glacial geologists on the one hand, and geocryologists and permafrost scientists on the other.