29 August 2013 Last updated at 18:00 GMT
Huge canyon discovered under Greenland ice
By Roger Harrabin
One of the biggest canyons in the world has been found beneath the ice sheet that smothers most of Greenland.
The canyon - which is 800km long and up to 800m deep - was carved out by a great river 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 British Antarctic Survey said it was remarkable to find so huge a geographical feature previously unseen.
Read more: http://www.bbc.co.uk/news/science-environment-23866810