August 30, 2013
One of the biggest canyons in the world has been discovered beneath the Greenland ice sheet. 800km long and up to 800m deep - the canyon was carved out more than four million years ago, before the ice arrived. It was discovered by accident as scientists researching climate change mapped Greenland’s bedrock by radar.
The hidden valley is longer than the Grand Canyon in Arizona. It traverses from the centre of Greenland to the northern coastline and before the ice sheet was formed it would have contained a river gushing into the Arctic Ocean. Now it is packed with ice.
The ice sheet, up to 3km (2 miles) thick, is now so heavy that it makes the island sag in the middle (central Greenland was previously about 500m above sea level, now it is 200m below sea level).
The canyon was discovered by using radar to bounce signals back off the bedrock underneath. Researchers are trying to find out how much will the Greenland ice sheet contribute to sea level rise if, as predicted, the Arctic continues to warm as greenhouse gases increase. Studying the data collected over decades, they were amazed to stumble across the canyon.
The lead author, Prof Jonathan Bamber of Bristol University said: "With satellite images instantly available on a mobile phone we could assume that the Earth has been fully mapped, but there's clearly a lot left to discover. We're incredibly excited about this - it really is a once-in-a-lifetime discovery to find something on this scale."
Prof David Vaughan from British Antarctic Survey said: “The Greenland and Antarctic ice sheets hide a lot. It’s pretty surprising to find this canyon. Greenland isn’t that big for a canyon of that size, and for it to survive in its pre-glacial form after successive glaciations is quite something.”
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