Interactions between glaciers and permafrost an introduction
CHARLES HARRIS1 & JULIAN B. MURTON2
1 School of Earth, Ocean and Planetary Sciences, Cardiff University, Cardiff, UK 2Department of Geography, University of Sussex, Brighton, UK
Abstract: 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 andgeocryologycan 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 glaciersare associated with the presence of ground ice, and represent a landform that straddles the semantic fence separatingglacial featuresfrom 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.
The cryosphere (derived from the Greek kryos, meaning 'cold') refers to those parts of the Earth's surface where water is dominantly frozen, and includes areas with snow cover, seaice, glaciers和永久冻土。冰冻圈对位的监控meters that currently contribute to the Global Climate Observation System includes the temperature of cold firn, glacier size and mass balance, timing of lake and river freeze-up and break-up, permafrost temperature, active-layer thickness, and snow cover area and water equivalent (Dyurgerov & Meier 1997; Vinnikov et al. 1999; Armstrong & Brodzik 2001; Harris et al. 2001). Complex interactions amongst these parameters and their feedback effects on geomorphological processes (French 1996; Benn & Evans 1998), the behaviour of cold-based glaciers and ice sheets (Cutler et al. 2000; Waller 2001), the global climate system (Etkin & Agnew 1992; IPCC 2001) and the long-term evolution ofcold landscapes(Fulton 1989; Ballantyne & Harris 1994) underline the importance of studying the cryosphere from an interdisciplinary perspective. This book con siders some of the key interactions between glaciers and permafrost.
In a geological context, glaciers andglacial processeshave generated more scientific literature than permafrost and related phenomena, almost certainly because mid- and high-latitude landscapes often show clear evidence for glaciation, both in the form of erosional and depositional landforms. Research into permafrost and frozen ground phenomena began with early observations by Russian scientists and explorers in Siberia (Yershov 1998), but has since lagged behind studies of glaciers and glacial processes. Initially the term geocryology (Russian geokriologiya) was used to describe the science of the cryosphere, including both frozen ground and glaciers (Fyodorov & Ivanov 1974). However, a dichotomy betweenthe study of glaciers(glaciology) and frozen ground resulted from the introduction of the term periglacial by Lozinski (1909, 1912) to describe the cold-climate conditions in the zone adjacent to but beyond the Pleistocene glaciers, and the distinctive frost-related geomorphological pro
From: Harris, C. & Murton, J. B. (eds) 2005. Cryospheric Systems: Glaciers and Permafrost. Geological Society, London, Special Publications, 242, 1-9. 0305-8719/05/$15.00 © The Geological Society of London 2005.
cesses that prevailed there (Haeberli 2005). Through the twentieth century, the field of geo-cryology has come to exclude glaciers and to focus冰冻的地面上phenomena (Washburn 1979; Yershov 1998). As Haeberli points out, the geological and geomorphological processes at the interface between glaciers and permafrost have therefore received less attention than they warrant, and the influence of one on the other has been largely neglected. The present chapter discusses the glacier-permafrost interactions that underpin (1) glacitectonic processes, (2) ground-ice development, (3) rock glaciers,
(4) proglacial and ice-marginal processes and
(5) permafrost and related processes.
Continue reading here:Case Histories of glacierpermafrost Interaction
Was this article helpful?