We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ?

Stokes, C.R. and Clark, C.D. (2003) 'Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ?', Geology., 31 (4). pp. 347-350.


Elucidating the controls on the location and vigor of ice streams is crucial to understanding the processes that lead to fast disintegration of ice flows and ice sheets. In the former North American Laurentide ice sheet, ice stream occurrence appears to have been governed by topographic troughs or areas of soft-sediment geology. This paper reports robust evidence of a major paleo–ice stream over the northwestern Canadian Shield, an area previously assumed to be incompatible with fast ice flow because of the low relief and relatively hard bedrock. A coherent pattern of subglacial bedforms (drumlins and megascale glacial lineations) demarcates the ice stream flow set, which exhibits a convergent onset zone, a narrow main trunk with abrupt lateral margins, and a lobate terminus. Variations in bedform elongation ratio within the flow set match theoretical expectations of ice velocity. In the center of the ice stream, extremely parallel megascale glacial lineations tens of kilometers long with elongation ratios in excess of 40:1 attest to a single episode of rapid ice flow. We conclude that while bed properties are likely to be influential in determining the occurrence and vigor of ice streams, contrary to established views, widespread soft-bed geology is not an essential requirement for those ice streams without topographic control. We speculate that the ice stream acted as a release valve on ice-sheet mass balance and was initiated by the presence of a proglacial lake that destabilized the ice-sheet margin and propagated fast ice flow through a series of thermomechanical feedbacks involving ice flow and temperature.

Item Type:Article
Additional Information:Email Dr Chris Stokes at for a copy of the offprint.
Keywords:Ice stream, Laurentide ice sheet, Canadian Shield.
Full text:Full text not available from this repository.
Publisher Web site:<0347:LISOTC>2.0.CO;2
Date accepted:No date available
Date deposited:No date available
Date of first online publication:April 2003
Date first made open access:No date available

Save or Share this output

Look up in GoogleScholar