Report

Paleofluvial Mega-Canyon Beneath the Central Greenland Ice Sheet

Science  30 Aug 2013:
Vol. 341, Issue 6149, pp. 997-999
DOI: 10.1126/science.1239794

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Ice Lubricant

The Greenland and Antarctic ice sheets both possess hydrological systems that allow water accumulating from the melting of surface ice to be transported to the base of the ice sheet. If that water, when it reaches the ice-bedrock interface, is distributed over large areas, it will lubricate rapid ice sheet flow toward the sea. Bamber et al. (p. 997) report the existence of a large, 750-km-long subglacial canyon in northern Greenland, which may act as a channel for the transport of basal meltwater to the margin of the ice sheet and thus influence overall ice sheet dynamics.

Abstract

Subglacial topography plays an important role in modulating the distribution and flow of basal water. Where topography predates ice sheet inception, it can also reveal insights into former tectonic and geomorphological processes. Although such associations are known in Antarctica, little consideration has been given to them in Greenland, partly because much of the ice sheet bed is thought to be relatively flat and smooth. Here, we present evidence from ice-penetrating radar data for a 750-km-long subglacial canyon in northern Greenland that is likely to have influenced basal water flow from the ice sheet interior to the margin. We suggest that the mega-canyon predates ice sheet inception and will have influenced basal hydrology in Greenland over past glacial cycles.

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