Interactions between glaciers and permafrost: an introduction
A consideration of the interactions between glaciers and permafrost is essential to many environmental studies of cold regions. This paper reviews how concepts, field data and experimental studies from glaciology and geocryology can provide a basis for improved understanding of some of the key glacier-permafrost interactions at scales ranging from continental ice sheets to small proglacial streams. Glacitectonic processes are strongly influenced by water pressures beneath subglacial and proglacial permafrost, and by the amount of unfrozen water within the permafrost. Burial of glacier ice and growth of intra-sedimental ice also occur within sub- and proglacial permafrost, and together they produce a complex assemblage of ground ice in glaciated frozen lowlands. In mountain regions, rock glaciers are associated with the presence of ground ice, and represent a landform that straddles the semantic fence separating glacial features from permafrost features. In proglacial and ice-marginal environments, geomorphological activity reflects the combined effects of glacially- and periglacially-conditioned processes operating synchronously in adjacent areas, or in succession; such activity includes the transport of sediment in glacierized catchments and the calving of glacial ice in ice-marginal lakes. Interaction between permafrost and glacial phenomena depends largely on their proximity: where permafrost occurs close to glaciers, the thermal regime of the active layer is influenced in part by the surface covering of adjacent glacial ice through its effect on albedo and ground heat flux. Glacier-permafrost interactions are particularly important in recently deglaciated terrain, where permafrost may be aggrading. This ‘paraglacial’ zone often shows rapid geomorphological change. Thus, glacier-permafrost interactions are complex and occur over a wide range of temporal and spatial scales.
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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.