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Durham University

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Publication details for Professor Antony Long

Roberts, D.H. & Long, A.J. (2005). Streamlined bedrock terrain and fast ice flow, Jakobshavns Isbrae, West Greenland: implications for ice stream and ice sheet dynamics. Boreas 34(1): 25-42.

Author(s) from Durham


This study investigates the marginal subglacial bedrock bedforms of Jakobshavns Isbrae, West Greenland, in order to examine the processes governing bedform evolution in ice stream and ice sheet areas, and to reconstruct the interplay between ice stream and ice sheet dynamics. Differences in bedform morphology (roche moutonnée or whaleback) are used to explore contrasts in basal conditions between fast and slow ice flow. Bedform density is higher in ice stream areas and whalebacks are common. We interpret that this is related to higher ice velocities and thicker ice which suppress bed separation. However, modification of whalebacks by plucking occurs during deglaciation due to ice thinning, flow deceleration, crevassing and fluctuations in basal water pressure. The bedform evidence points to widespread basal sliding during past advances of Jakobshavns Isbrae. This was encouraged by increased basal temperatures and melting at depth, as well as the steep marginal gradients of Jakobshavns Isfjord which allowed rapid downslope evacuation of meltwater leading to strong ice/bedrock coupling and scouring. In contrast to soft-bedded ice stream bedforms, the occurrence of fixed basal perturbations and higher bed roughness in rigid bed settings prevents the basal ice subsole from maintaining a stable form which, coupled with secondary plucking, counteracts the development of bedforms with high elongation ratios. Cross-cutting striae and double-plucked, rectilinear bedforms suggest that Jakobshavns Isbrae became partially unconfined during growth phases, causing localised diffluent flow and changes in ice sheet dynamics around Disko Bugt. It is likely that Disko Bugt harboured a convergent ice flow system during repeated glacial cycles, resulting in the formation of a large coalesced ice stream which reached the continental shelf edge.


Anandakrishnan, S., Blankenship, D. D. & Alley, R. B. 1998:
Influence of subglacial geology on the position of a West Antarctic ice stream from seismic observations. Nature 394, 62–65.
Bell, R. E., Blankenship, D. D. & Finn, C. A. 1998: Influence of subglacial geology on the onset of a West Antarctic ice stream from aerogeophysical observations. Nature 394, 58–62.
Bindschadler, R. 1984: Jakobshavns glacier drainage basin: a balance assessment. Journal of Geophysical Research 89, 2066–2072.
Canals, M., Urgeles, R. & Calafat, A. M. 2000: Deep sea-floor evidence of past ice streams off the Antarctic Peninsula. Geology 28, 31–34.
Clark, C. D. 1993: Mega scale glacial lineations and cross cutting ice flow landforms. Earth Surface Processes and Landforms 18, 1–29.
Clark, C. D. 1999: Glaciodynamic context of subglacial bedform generation and preservation. Annals of Glaciology 28, 23–32.
Clark, C. D. & Stokes, C. R. 2001: Extent and basal characteristics of the M’Clintock Channel ice stream. Quaternary International 86, 81–101.
Clarke, T. S. & Echelmeyer, K. 1996: Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavn Isbrae, West Greenland. Journal of Glaciology 43, 219–232.
Echelmeyer, K. A. & Harrison, W. D. 1990: Jakobshavn Isbrae, West Greenland: seasonal variations in velocity – or lack thereof.
Journal of Glaciology 36, 82–88.
Echelmeyer, K. A., Harrison, W. D., Larsen, C. & Mitchell, J. E.
1994: The role of the margins in the dynamics of an active ice stream. Journal of Glaciology 40, 527–538.
Evans, I. S. 1996: Abraded rock landforms (whalebacks) developed under ice streams in mountain areas. Annals of Glaciology 22, 9–16.
Fastook, J. L. & Hughes, T. J. 1994: A plan to model iceberg outbursts from Greenland outlet glaciers in response to greenhouse warming. In Rhee, N. (ed.): Report on the Workshop on the Calving Rate of West Greenland Glaciers in Response to Climate Change, 21–36. Danish Polar Center, University of Copenhagen.
Funder, S. & Hansen, L. 1996: The Greenland ice sheet: a model for its culmination and decay during and after the last glacial maximum.
Bulletin of the Geological Society of Denmark 42, 137–152.
Glasser, N. & Warren, C. 1990: Medium scale landforms of glacial erosion in southern Greenland: process and form. Geografiska Annaler 72A, 211–215.
Gordon, J. E. 1981: Ice scoured topography and its relationships to bedrock structure and ice movement in parts of northern Scotland and West Greenland. Geografiska Annaler 63A, 55–65.
Hall, A. & Glasser, N. 2003: Reconstructing the basal thermal regime of an ice stream in a landscape of selective linear
erosion: Glen Avon, Cairngorm Mountains, Scotland. Boreas 32, 191–208.
Hughes, T. 1986: The Jakobshavns effect. Geophysical Research Letters 13, 46–48.
Iken, A., Echelmeyer, K. A., Harrison, W. D. & Funk, M. 1993:
Mechanisms of fast flow in Jakobshavn Isbrae, West Greenland:
Part 1. Measurements of temperature and water-level in deep boreholes. Journal of Glaciology 39, 15–25.
Jansson, K. N., Stroeven, A. P. & Kleman, J. 2003: Configuration and timing of Ungava Bay ice streams, Labrador–Ungava, Canada. Boreas 32, 256–263.
Lindstrom, E. 1988: Are roche moutonne´es mainly preglacial forms? Geografiska Annaler 70A, 323–331.
Long, A. J. & Roberts, D. H. 2002: A revised chronology for the ‘Fjord Stade’ moraine in Disko Bugt, West Greenland. Journal of Quaternary Science 17, 561–579.
Long, A. J. & Roberts, D. H. 2003: Late Weichselian deglacial history of Disko Bugt, West Greenland, and the dynamics of the Jakobshavns Isbrae ice stream. Boreas 32, 208–226.
Lowe, A. L. & Anderson, J. B. 2002: Late Quaternary advance and retreat of the West Antarctic Ice Sheet in Pine Island Bay, Antarctica. Quaternary Science Reviews 21, 1879–1897.
Luthi, M., Funk, M., Iken, A., Gogineni, S. & Truffer, M. 2002:
Mechanisms of fast flow in Jakobhavns Isbrae, West Greenland:
Part III. Measurements of ice deformation, temperature and cross borehole conductivity in boreholes to the bedrock. Journal of Glaciology 48, 369–384.
Rastas, J. & Seppala, M. 1981: Rock jointing and abrasion forms on Roche Moutoune´es, SW Finland. Annals of Glaciology 28, 67–74.
Sejrup, H. P., Larsen, E., Haflidason, H., Berstad, I. M., Hjelstuen, B.
O., Jonsdottir, H., King, E. L., Landvik, J., Longva, O., Nygard, A., Ottesen, D., Raunholm, S., Rise, L. & Stalsberg, K. 2003:
Configuration history and impact of the Norwegian Channel ice stream. Boreas 32, 18–37.
Sharp, M., Dowdeswell, J. A. & Gemmell, J. C. 1989: Reconstructing past glacier dynamics and erosion from geomorphic evidence, Snowdon, North Wales. Journal of Quaternary Science 4, 115–130.
Smith, A. M. 1997: Variations in basal conditions on Rutford ice stream, west Antarctica. Journal of Glaciology 43, 245–255.
Stokes, C. R. & Clark, C. D. 1999: Geomorphological criteria for identifying Pleistocene ice streams. Annals of Glaciology 28, 67–74.
Stokes, C. R. & Clark, C. D. 2001: Palaeo-ice streams. Quaternary Science Reviews 20, 1437–1457.
Stokes, C. R. & Clark, C. D. 2002: Are long subglacial bedforms indicative of fast ice flow? Boreas 31, 239–249.
Sugden, D. E., Glasser, N. & Clapperton, C. M. 1992: Evolution of large roche moutonne´es. Geografiska Annaler 74A, 253–264.
Ten Brink, N. W. & Weidick, A. 1974: Greenland ice sheet history since the last glaciation. Quaternary Research 4, 429–440.
Truffer, M. & Echelmeyer, K. A. 2003: Of isbrae and ice streams.
Annals of Glaciology 36, 66–72.
Tulaczyk, S. M., Scherer, R. P. & Clark, C. D. 2001: A ploughing model for the origin of weak tills beneath ice streams: a qualitative treatment. Quaternary International 86, 59–70.
Warren, C. R. & Hulton, N. R. J. 1990: Topographic and glaciological controls on Holocene ice-sheet margin dynamics, central West Greenland. Annals of Glaciology 14, 307–310.
Weidick, A. 1968: Observations on some Holocene glacier fluctuations in West Greenland. Meddelelsser om Grønland 165, 1–202.
Weidick, A. 1972: Holocene shorelines and glacial stages in Greenland – an attempt at correlation. Grønlands Geologiske Undersøgelse 41, 1–39.
Weidick, A. 1985: Review of glacier changes in West Greenland.
Zeitschrift fu¨r Gletscherkunde und Glazialgeologie 21, 301–309.
Weidick, A. 1994: Fluctuations of West Greenland calving glaciers.
In Rhee, N. (ed.): Report on the Workshop on the Calving Rate of West Greenland Glaciers in Response to Climate Change, 141–168. Danish Polar Center, University of Copenhagen.
Weidick, A. 1996: Neoglacial changes of ice cover and sea level in Greenland – a classical enigma. In Grønnow, B. (ed.): The Palaeo-Eskimo Cultures of Greenland: New Perspectives in Greenlandic Archaeology, 257–270. Danish Polar Center, University of Copenhagen.
Zwally, H. J., Abdalati, W., Herring, T., Larson, K., Saba, J. & Steffen, K. 2002: Surface melt-induced acceleration of Greenland ice-sheet flow. Science 297, 218–222.