Subglacial Greenland Canyon System Rivals The Grand Canyon

The canyon is at least 750km long and in places as much as 800m deep and is on the same scale as parts of the Grand Canyon in Arizona, USA.

This remarkable, previously unknown, feature is thought to predate the ice sheet that has covered Greenland for the last few million years and has the characteristics of a meandering river channel. By comparison, the longest river in the UK, the River Severn, is about 350km long and much less wide and deep.

Professor Jonathan Bamber of Bristol's School of Geographical Sciences, lead author of the study, said: "With Google Streetview available for many cities around the world and digital maps for everything from population density to happiness one might assume that the landscape of the Earth has been fully explored and mapped. Our research shows there's still a lot left to discover."

The scientists used thousands of kilometres of airborne radar data, collected mainly by NASA and researchers from the UK and Germany over several decades, to piece together the landscape lying beneath the ice sheet that covers most of Greenland and obscures it from view.

At certain frequencies, ice is transparent to radio waves which can travel through the ice and bounce off the bedrock underneath. By analysing all the radar data in a consistent way the team discovered a continuous bedrock canyon that extends from almost the centre of the island and ends at its northern extremity in a deep fjord connecting to the Arctic ocean.

They believe the canyon plays an important role in transporting sub-glacial meltwater produced at the bed from the interior to the edge of the ice sheet and ultimately into the ocean. Even before the presence of the ice sheet, going back at least four million years, the evidence suggests the canyon provided a pathway for water from the interior to the coast and was a major fluvial system.

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