Hidden Beneath the Ice: A Massive Discovery in Greenland

Sophie Janaskie
By Sophie Janaskie December 21, 2013 20:42
A section of the ice sheet covering Greenland. Researchers estimate that the ice sheet dates back to 4 million years ago. Image courtesy of Hannes Grobe.

A section of the ice sheet covering Greenland. Researchers estimate that the ice sheet dates back to 4 million years ago. Image courtesy of Hannes Grobe.

Throughout the past century, scientists and researchers have pushed the frontiers of knowledge to new limits. They have explored the depths of the ocean, landed rovers on Mars, and developed a deeper understanding of the human brain and body. In the wake of these discoveries and in the age of GoogleMaps and GIS, one would think that we have explored all there is to explore. However, a new finding suggests there may be more left to discover than we originally thought.

A research group led by Jonathan Bamber of Bristol’s School of Geographical Studies has recently uncovered a never-before-seen mega-canyon in northern Greenland. This massive geological feature, which measures about 460 miles in length and up to 2,600 feet in depth, stretches from the center of Greenland all the way to the Petermann Glacier fjord on the northern coast.

During the winter months, an ice sheet covers as much as 80% of Greenland’s landmass. Image courtesy of Eric Gaba.

During the winter months, an ice sheet covers as much as 80% of Greenland’s landmass. Image courtesy of Eric Gaba.

But how did this enormous canyon, which in some locations is comparable in scale to the Grand Canyon, escape our notice for so long? Simple: it is buried under more than a mile of ice.

Most glacial researchers study coastlines, where the ice is most unstable and most likely to affect the global sea level. Bamber’s team, however, did not limit their scope so narrowly. Their study encompassed the entire island of Greenland, drawing from the data of prior studies across a 40-year period.

In the beginning, Bamber’s team had simply hoped to investigate the portion of Greenland’s landscape that was hidden by ice. From previous investigations, researchers knew that ice-covered geological features were important, though unseen. Topography below glacial ice affects the flow and path of meltwater, which are key in understanding glacial movements and global sea level rise. In addition, landscape features that predate the ice sheet can reveal important insights into the history and geology of the region.

NASA’s Operation IceBridge used airborne radar to collect data on the topography hidden beneath the ice sheet. Image courtesy of NASA.

NASA’s Operation IceBridge used airborne radar to collect data on the topography hidden beneath the ice sheet. Image courtesy of NASA.

But when the team set its sights on Greenland, it certainly did not expect to find anything of this magnitude. “You know, it’s not every year, it’s not every decade, it’s not every five decades that you discover something quite as substantial and extensive as a feature like this, so it was a big surprise for us,” Bamber said in an interview with NPR. It was not until they analyzed a significant portion of the data that they noticed a large anomaly in the center of Greenland.

One of Bamber’s major data sources was NASA’s IceBridge, a six-year mission that monitored how Earth’s polar ice caps were changing. IceBridge researchers employed an instrument called a multichannel coherent radar depth sounder to carry out their survey. This device emits ice-penetrating radio waves, enabling it to measure geological characteristics of the bedrock beneath the glacier. Using this data, Bamber’s team was able to generate a 3D map of the canyon’s landscape. He found that over this area, radio waves took a much longer time to bounce back to the radar device, indicating a large depression in the topography.

Unlike valleys formed from glacial erosion, this mega-canyon is not U-shaped. Rather, its sharply-defined features, meandering path, and steep slopes suggest that a river once carved its way through the bedrock. These characteristics place the canyon’s age at over four million years old — the last time Greenland was not covered in glaciers. These days, the canyon seems to play a key role in the transport of the ice’s meltwater to the ocean.

Radar data enabled Bamber’s team to produce a three-dimensional map of the canyon’s topography. Image courtesy of Jonathan Bamber.

Radar data enabled Bamber’s team to produce a three-dimensional map of the canyon’s topography. Image courtesy of Jonathan Bamber.

The team’s discovery is a huge step for geological research because it demonstrates that there is still much to explore on Earth. “One might assume that the landscape of the Earth has been fully explored and mapped,” said Bamber. “Our research shows there’s still much left to discover.”

What else might be left? Although Bamber expressed doubt that another geological feature of this magnitude remains hidden, he did not rule out the possibility. Many landscapes hidden by ice sheets remain unexplored and unstudied, as do other areas of our planet. Whether it is the deep sea, ice sheets, remote islands, or high mountaintops, this discovery leaves no doubt that we still have much left to learn about our planet.

Sophie Janaskie
By Sophie Janaskie December 21, 2013 20:42