National Geographic News
Photo of the Ellsworth Mountain range in West Antarctica.

A huge subglacial pit was found near West Antarctica's Ellsworth Mountains.

Photograph by Robert Boesch, Corbis

Ker Than

for National Geographic

Published January 17, 2014

Scientists probing the icelands of West Antarctica have discovered a subglacial pit that is deeper than the Grand Canyon.

The researchers were charting the Ellsworth Subglacial Highlands-an ancient mountain range buried beneath several miles of Antarctic ice-by combining data from satellites and ice-penetrating radar towed behind snowmobiles and onboard small aircraft.

The project uncovered a massive subglacial trench, or valley, that is up to 1.9 miles (3 kilometers) deep and more than 15.5 miles (25 kilometers) across. For comparison, the Grand Canyon is 1.13 miles (1.8 kilometers) deep at its deepest point. In places, the floor of the subglacial valley is more than 6,500 feet (2,000 meters) below sea level.

"It's a huge privilege to be able to reveal another piece of the jigsaw puzzle that is the surface of our Earth," said study team member Neil Ross, a geophysicist at Newcastle University in the U.K.

Scientists aren't sure exactly when the valley was created, except that it was tens of millions of years ago. "What we do know is that Antarctica has been glaciated for at least 34 million years, and during this time the ice in West Antarctica would have oscillated in size from the small ice-field conditions ... to the large ice sheet that we see today," Ross said.

The team speculates that the valley was initially formed when a river exploited a geological weakness, such as a geological fault. However, it was glaciers that did the hard work of deepening the valley.

"A river cannot incise a valley below sea level. [This type of deepening] needs erosion by glaciers," Ross said.

Scientists had previously known about some parts of the valley, such as Subglacial Lake Ellsworth, but they had no idea how large the trough really was until now. Ross said that his group was in a unique position to "join the dots" and discover something that others had missed.

"The only reason that we can have confidence in the satellite data revealing the full extent of the trough was because we could prove the dimensions of the trough from the ice-penetrating radar data at either end," he added.

"It was also very fortuitous that I had worked as a postdoc on the two projects that surveyed either end of the trough."

The research is detailed in the current issue of the Geological Society of America Bulletin.

Follow Ker Than on Twitter.

19 comments
Tim Jensen
Tim Jensen

Were the ice gone, would it be a lake or a canyon? If parts of it were 6500' below sea level, I think much of it would be. It seems to be as much of a "valley" as Lake Baikal is. 


Denniss Giesbrecht
Denniss Giesbrecht

"Trenches are formed as a result of plate tectonics, or the movement of the Earth’s crust. Tectonic plates slip underneath each other in a process known as subduction." 


education.nationalgeographic.com/education/encyclopedia/ocean-trench/?ar_a=1

Wendy Allen
Wendy Allen

I would love to see Nat Geo do a TV documentary on that discovery, it would be so interesting

hopefully will see that in the future, keep an eye out for more discoveries around this part of Antarctica - wow amazing

Francisco Madrigal
Francisco Madrigal

Rivers do not create canyons but canyons create rivers, as gaciers just do not carve valleys or canyons. I can demonstrate that but people just don't want to listen to me. Who's going to be the first, National Geographic...? I don't think so...

Francine Brewin
Francine Brewin

very interesting to know that there is always something new to learn about our planet and the universe, 

Anna Ruščák
Anna Ruščák

Fantastic discovery, especially because of its spectacular size.

Shane Andrews
Shane Andrews

As much as I love Space, I think more money, technology, manpower and resources should be diverted to the study of our Home. There is still so much we don't know, don't understand, and haven't discovered right here on Earth.

David John Owsley
David John Owsley

Amazing and great to know we still don't know our own planet...

Amir Patel
Amir Patel

@Shane Andrews There isnt enough money being used to fund space nor earth exploration and science. its all being funneled into the military organisations of the world. 

Calvin Eld-Weaver
Calvin Eld-Weaver

@Francisco Madrigal @Jonathan BelzWhat is there to debate? Are you suggesting that the Grand Canyon, USA or the Copper Canyon in Mexico were formed first and then a river appeared at the bottom?


It is often better to remain silent and have people only think you are a fool, rather than speak and leave them in no doubt.

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