Mega-Canyon Discovered Beneath Greenland Ice   
       
   August 29, 2013:  Data from a NASA airborne science mission has revealed an   
   immense and previously unknown canyon hidden under a mile of Greenland ice.   
       
   "One might assume that the landscape of the Earth has been fully explored and   
   mapped," said Jonathan Bamber, professor of physical geography at the   
   University of Bristol in the United Kingdom, and lead author of the study   
   published in today's issue of Science. "Our research shows there's still a lot   
   left to discover."   
       
   https://www.youtube.com/watch?v=ENg9Hci9y3M   
       
   Greenland Megacanyon (splash)   
   Hidden for all of human history, a 460 mile long canyon has been discovered   
   below Greenland's ice sheet. Using radar data from NASA's Operation IceBridge,   
   scientists found the canyon runs from near the center of the island northward   
   to the fjord of the Petermann Glacier. Play the video   
       
   The canyon has the characteristics of a winding river channel and is at least   
   460 miles (750 kilometers) long, making it longer than the Grand Canyon. In   
   some places, it is as deep as 2,600 feet (800 meters), on scale with segments   
   of the Grand Canyon. This immense feature is thought to predate the ice sheet   
   that has covered Greenland for the last few million years.   
       
   The scientists used thousands of miles of airborne radar data, collected by   
   NASA and researchers from the United Kingdom and Germany over several decades,   
   to piece together the landscape lying beneath the Greenland ice sheet.   
       
   A large portion of this data was collected from 2009 through 2012 by NASA's   
   Operation IceBridge, an airborne science campaign that studies polar ice. One   
   of IceBridge's scientific instruments, the Multichannel Coherent Radar Depth   
   Sounder, can see through vast layers of ice to measure its thickness and the   
   shape of bedrock below.   
       
   In their analysis of the radar data, the team discovered a continuous bedrock   
   canyon that extends from almost the center of the island and ends beneath the   
   Petermann Glacier fjord in northern Greenland.   
       
   At certain frequencies, radio waves can travel through the ice and bounce off   
   the bedrock underneath. The amount of times the radio waves took to bounce   
   back helped researchers determine the depth of the canyon. The longer it took,   
   the deeper the bedrock feature.   
       
   http://www.nasa.gov/mission_pages/icebridge/index.html#.UiBzkPAo4dU   
       
   An Operation Icebridge P-3B research plane in Greenland.   
       
   "Two things helped lead to this discovery," said Michael Studinger, IceBridge   
   project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "It   
   was the enormous amount of data collected by IceBridge and the work of   
   combining it with other datasets into a Greenland-wide compilation of all   
   existing data that makes this feature appear in front of our eyes."   
       
   The researchers believe the canyon plays an important role in transporting   
   sub-glacial meltwater from the interior of Greenland to the edge of the ice   
   sheet into the ocean. Evidence suggests that before the presence of the ice   
   sheet, as much as 4 million years ago, water flowed in the canyon from the   
   interior to the coast and was a major river system.   
       
   "It is quite remarkable that a channel the size of the Grand Canyon is   
   discovered in the 21st century below the Greenland ice sheet," said Studinger.   
   "It shows how little we still know about the bedrock below large continental   
   ice sheets."   
       
   The IceBridge campaign will return to Greenland in March 2014 to continue   
   collecting data on land and sea ice in the Arctic using a suite of instruments   
   that includes ice-penetrating radar.   
       
   Credits:   
       
    Production editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   Related Links:   
       
   http://www.nasa.gov/mission_pages/icebridge/index.html#.UiB2DvAo4dV   
   Operation Icebridge  -- home page   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.94   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)