科学家们发现，在格陵兰的冰帽下面有一个大峡谷，这个峡谷有750公里长，深度与美国的大峡谷相当。
科学家们把几十年来通过飞机收集的雷达数据拼接起来，形成了一张隐藏在冰雪之下不为人所见的大峡谷的图形。
他们相信，这条大峡谷曾经是一条主要的水道，在大约4百万年前被冰雪覆盖。
即使到今天，这条大峡谷仍然把冰川融化的水输送到冰原的边际，并汇入大洋。
这条大峡谷起源于格陵兰岛的中部，通往格陵兰岛的北部海岸。
A massive canyon has been discovered beneath the Greenland ice. 科学家发现格陵兰冰帽下750公里长大峡谷
Scientists have discovered a massive canyon hidden almost two kilometers under Greenland’s ice cap.
The canyon is at least 750 kilometers long and, according to the U.S. space agency, NASA, has the characteristics of a winding river channel. In some places the canyon is 800 meters deep, which is on a similar scale as the Grand Canyon.
NASA says the canyon was made before the ice formed over much of Greenland.
"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 Britain and lead author of the study. "Our research shows there's still a lot left to discover."
Using radar data collected over decades, NASA and researchers from Britain and Germany were able to piece together the landscape of the canyon. A large portion of this data was collected from 2009 through 2012 by NASA's Operation IceBridge, an airborne science program studying polar ice.
One instrument in particular, the Multichannel Coherent Radar Depth Sounder, can see through massive amounts of ice to the bedrock below. The canyon appears to extend from almost the center of the island and ends beneath the Petermann Glacier fjord in northern Greenland.
Researchers think that before Greenland was covered in ice - some 4 million years ago - water flowed through the canyon as part of a massive river system. Now, researchers say the canyon “plays an important role in transporting sub-glacial melt water from the interior of Greenland to the edge of the ice sheet into the ocean.”
"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 Michael Studinger, IceBridge project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It shows how little we still know about the bedrock below large continental ice sheets."
Bamber's team published its findings Thursday in the journal Science.
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