Hessbreen is a small valley glacier which last surged in 1974, and is typical of many polythermal glaciers in Svalbard. The present ice surface displays a wide range of structures that can be attributed to either quiescent-phase or surge-phase deformation. During quiescent-phase flow, primary stratification becomes slightly deformed into low-amplitude open folds, while a completely new structure, longitudinal foliation, develops in axial-planar relationship to these folds. The propagation of a surge front is associated with the formation of thrusts; however, not all of these break through to the surface. As the surge progresses, and the ice behind the surge front becomes extensional, the surface of the glacier breaks up into numerous crevasses, of which several hundred metre long transverse crevasses, convex up-glacier, are dominant. After a period of quiescence, these become degraded into crevasse traces, planar structures which are steeply dipping and have many different orientations. Overall, most ice which reaches the snout has not undergone significant cumulative strain, as indicated by the lack of deformation of both the primary structures and the later crevasse traces. The distribution of debris in Hessbreen is controlled strongly by the development of some of these structures. Angular supraglacial debris is intimately associated with stratification, while basal debris is lifted to en- and supraglacial positions in association with thrusting.
Hessbreen is a small valley glacier which last surged in 1974, and is typical of many polythermal glaciers in Svalbard. The present ice surface displays a wide range of structures that can be attributed to either quiescent-phase or surge-phase deformation. During quiescent-phase flow, primary stratification becomes slightly deformed into low-amplitude open folds, while a completely new structure, longitudinal foliation, develops in axial-planar relationship to these folds. The propagation of a surge front is associated with the formation of thrusts; however, not all of these break through to the surface. As the surge progresses, and the ice behind the surge front becomes extensional, the surface of the glacier breaks up into numerous crevasses, of which several hundred metre long transverse crevasses, convex up-glacier, are dominant. After a period of quiescence, these become degraded into crevasse traces, planar structures which are steeply dipping and have many different orientations. Overall, most ice which reaches the snout has not undergone significant cumulative strain, as indicated by the lack of deformation of both the primary structures and the later crevasse traces. The distribution of debris in Hessbreen is controlled strongly by the development of some of these structures. Angular supraglacial debris is intimately associated with stratification, while basal debris is lifted to en- and supraglacial positions in association with thrusting.
Considering that glaciers and ice sheets cover about 10% of the Earth's land surface in a world where human civilization is increasingly impacted by the effects of changing glacial activity, Colour Atlas of Glacial Phenomena presents itself as an indispensable guide for students, professionals, and researchers who want to be better informed while studying and tracking the future influences of glaciers and ice sheets on the global environment. While stressing both the beauty and utility of glaciers, the authors cover critical features of glaciers and their landforms and provide useful explanations of the key concepts in glaciology and glacial geology. The authors expand to demonstrate how our lives are influenced by the Cryosphere, a key component of the Earth system and how this heightens the vulnerability of glaciers and ice sheets to deterioration. This illustrated book also helpfully maps out regions of mountain glaciers and ice caps around the world for a practical reference and discusses the products of glacial erosion and deposition integral to understanding rising global sea levels.
Abstract Observations at the snouts of several glaciers in Spitsbergen indicate that, between their present apparent limits and the moraines dating from the maximum Holocene extent of ice, wide areas of outwash deposits underlain by dead glacier ice occur. Such ice was visible at a number of localities. Indirect evidence of dead ice includes kettle-holes, collapse structures and, in one case, a subglacial melt stream emerging as a fountain within one such plain. Aufeis , formed in early winter, can sometimes also be preserved in the long term if covered by fluvio-glacial material. The presence of such ice has implications for the interpretation of soft-sediment structures in glacigenic successions. Previously, many folds and faults have been interpreted as resulting from active ice overriding or pushing the sediment. Simple ablation beneath the sedimentary layer in question also gives rise to similar structures.
This paper outlines the results of stable isotope (δD-δ 18 O) analysis of snow and glacier ice undertaken as part of a larger study concerning structural glaciology, debris entrainment and debris transport patterns at Midtre Lovénbreen, Svalbard.Samples of fresh snow were collected from the glacier surface in spring 1999 and samples of surface glacier ice and basal ice samples were collected in summer 1999.When plotted on bivariate co-isotopic diagrams (δD-δ 18 O), the slopes obtained for snow and unmodified glacier ice (6.4 and 6.9, respectively) are less steep than those for the basal ice layer and transverse ice layers on the ice surface (7.6 and 7.7, respectively).The difference in the slope of these lines is not statistically significant at the sample size (50) used in this study.The results indicate that although stable isotope analysis clearly has potential for studies of debris entrainment, transport and structural glaciology, difficulties remain with applying this technique.It is therefore not possible to apply these isotopic techniques to ice facies of unknown origins.In particular, large sample numbers are required to establish statistical differences and high-resolution sampling of specific ice facies may be necessary to establish isotopic differences.
J. Ehlers, P. L. Gibbard & J. Rose (eds) 1991. Glacial Deposits in Great Britain and Ireland. ix + 580 pp. Rotterdam, Brookfield: A. A. Balkema. Price Dfl. 185.00, £58.00 (hard covers). ISBN 90 6191 875 8. - Volume 130 Issue 2
GROVE, J. M. 2004. Little Ice Ages. Ancient and Modern. Volumes 1 and 2, 2nd ed. London, New York: Routledge. xxvi+402 pp; xiii+pp. 406–718. Price £325.00 (2-volume set); hard covers. ISBN 0 415 33422 5 (Vol. 1); 0 415 33423 3 (Vol. 2); 0 415 09948 X (2-volume set) - Volume 142 Issue 3
Stump, E. 1995. The Ross Orogen of the Transantarctic Mountains. xv + 284 pp. Cambridge, New York, Port Chester, Melbourne, Sydney: Cambridge University Press. Price £60.00, US $99.95 (hard covers). ISBN 0 521 43314 2. - Volume 134 Issue 1
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