Scientists discovered a hidden ravine longer than the Grand Canyon under mile-deep Greenland ice.

The 460 mile-long and 2,600 foot-deep canyon has characteristics that suggest it was once the bed of a massive winding river, a NASA press release reported.

"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. "Our research shows there's still a lot left to discover."

The findings come from a project that collected thousands of miles of airborne footage to look at Greenland's ancient ice sheets. The aim of the project was to map out the terrain lying under the frozen surface.

Information from the endeavor, called Operation Icebridge, uncovered "continuous bedrock canyon that extends from almost the center of the island and ends beneath the Petermann Glacier fjord in northern Greenland." The University of Bristol also collected airborne data.

Icebridge used radar data to see through the ice. The frequencies have the ability to bounce off bedrock lurking beneath the ice.

"Two things helped lead to this discovery," Michael Studinger, IceBridge project scientist at NASA's Goddard Space Flight Center, said. "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 iced over canyon plays an important role in transporting sub-glacial melt water through the center of Greenland and dumping it 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," Studinger said. "It shows how little we still know about the bedrock below large continental ice sheets."

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