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Glacier Surface (glacier + surface)

Distribution by Scientific Domains

Humanities and Social Sciences	60%

Selected Abstracts

Jökulhlaup-related Ice Fracture and Supraglacial Water Release During the November 1996 Jökulhlaup, Skeiðarárjökull, Iceland

GEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1-2 2001
R.I. Waller
During the initial stages of the November 1996 jökulhlaup at Skeiðarárjökull, Iceland, floodwaters burst onto the glacier surface via a series of fractures. This supraglacial drainage led to the formation of a number of distinct ice surface depressions, one of which is investigated in detail. The morphology and structural characteristics of this feature are described, as well as the sedimentology of an associated assemblage of debris-filled fractures. This work suggests that debris-charged subglacial floodwaters travelled up to the glacier surface, where supraglacial flow occurred initially via an extensive network of fractures, orientated parallel to the glacier margin. Supraglacial discharge became progressively more focused into a series of discrete outlets, leading to the mechanical erosion of a number of depressions on the glacier surface. The associated transfer of subglacially derived floodwaters to high levels within the glacier resulted in the rapid entrainment of large volumes of sediment which may influence the patterns, processes and products of ice-marginal sedimentation in the future. [source]

Imaging glacial sediment inclusions in 3-D using ground-penetrating radar at Kongsvegen, Svalbard,

JOURNAL OF QUATERNARY SCIENCE, Issue 5 2010
Tavi Murray
Abstract The quiescent-phase surge-type glacier, Kongsvegen, flows confluent with the continuously fast-flowing Kronebreen in northwestern Spitsbergen. The lower regions of Kongsvegen overlie glaciomarine sediments, which have been incorporated into the ice during multiple surge events. The resulting englacial structures are exposed at the surface and on a cliff section. These structures have variously been interpreted as thrusts, formed by compression, or sediment-filled crevasses, formed by extension. We collected a grid of closely spaced ground-penetrating radar profiles in the area adjacent to the cliff section. Several structures were imaged in 3-D, including a strong subhorizontal basal reflector, which was underlain by a second, weaker subhorizontal reflector. The basal reflector was occasionally reverse faulted, suggesting compression. Clear englacial features extended upwards from it, dipping up-glacier at angles of <40° and steepening towards the glacier surface; they had complex geometries that changed rapidly cross-glacier. The structures were orientated at ,30° to ice flow, suggesting modification by lateral compression from Kronebreen. Some of these englacial structures clearly crossed the basal reflector. We conclude that the englacial features imaged are not likely to be derived from crevasse filling and were probably formed by thrusting. The results contribute to our understanding of surge initiation and termination processes, and interpretation of features in the palaeorecord. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Moraine development at a small High-Arctic valley glacier: Rieperbreen, Svalbard

JOURNAL OF QUATERNARY SCIENCE, Issue 6 2001
Astrid Lyså
Abstract Ice-cored lateral and frontal moraine complexes, formed at the margin of the small, land-based Rieperbreen glacier, central Svalbard, have been investigated through field observations and interpretations of aerial photographs (1936, 1961 and 1990). The main focus has been on the stratigraphical and dynamic development of these moraines as well as the disintegration processes. The glacier has been wasting down since the ,Little Ice Age' (LIA) maximum, and between 1936 and 1990 the glacier surface was lowered by 50,60 m and the front retreated by approximately 900 m. As the glacier wasted, three moraine ridges developed at the front, mainly as melting out of sediments from debris-rich foliation and debris-bands formed when the glacier was polythermal, probably during the LIA maximum. The disintegration of the moraines is dominated by wastage of buried ice, sediment gravity-flows, meltwater activity and some frost weathering. A transverse glacier profile with a northward sloping surface has developed owing to the higher insolation along the south-facing ice margin. This asymmetric geometry also strongly affects the supraglacial drainage pattern. Lateral moraines have formed along both sides of the glacier, although the insolation aspect of the glacier has resulted in the development of a moraine 60 m high along its northern margin. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Formation and disintegration of a high-arctic ice-cored moraine complex, Scott Turnerbreen, Svalbard

BOREAS, Issue 4 2001
KARI SLETTEN
Englacial debris structures, morphology and sediment distribution at the frontal part and at the proglacial area of the Scott Turnerbreen glacier have been studied through fieldwork and aerial photograph interpretation. The main emphasis has been on processes controlling the morphological development of the proglacial area. Three types of supraglacial ridges have been related to different types of englacial debris bands. We suggest that the sediments were transported in thrusts, along flow lines and in englacial meltwater channels prior to, and during a surge in, the 1930s, before the glacier turned cold. Melting-out of englacial debris and debris that flows down the glacier front has formed an isolating debris cover on the glacier surface, preventing further melting. As the glacier wasted, the stagnant, debris-covered front became separated from the glacier and formed ice-cored moraine ridges. Three moraine ridges were formed outside the present ice-front. The further glacier wastage formed a low-relief proglacial area with debris-flow deposits resting directly on glacier ice. Melting of this buried ice initiated a second phase of slides and debris flows with a flow direction independent of the present glacier surface. The rapid disintegration of the proglacial morphology is mainly caused by slides and stream erosion that uncover buried ice and often cause sediments to be transported into the main river and out of the proglacial area. Inactive stream channels are probably one of the morphological elements that have the best potential for preservation in a wasting ice-cored moraine complex and may indicate former ice-front positions. [source]