Mega-canyon discovered beneath Greenland ice sheet

Aug 29, 2013
3-D view of the subglacial canyon, looking northwest from central Greenland. Credit: J. Bamber, University Bristol

A previously unknown canyon hidden beneath two kilometers of ice covering Greenland has been discovered by a group of scientists, led by a team from the University of Bristol.

The canyon is at least 750km long and in places as much as 800m deep and is on the same scale as parts of the Grand Canyon in Arizona, USA.

This remarkable, previously unknown, feature is thought to predate the that has covered Greenland for the last few million years and has the characteristics of a channel. By comparison, the longest river in the UK, the River Severn, is about 350km long and much less wide and deep.

Professor Jonathan Bamber of Bristol's School of Geographical Sciences, lead author of the study, said: "With Google Streetview available for many cities around the world and for everything from population density to happiness one might assume that the landscape of the Earth has been fully explored and mapped. Our research shows there's still a lot left to discover."

The scientists used thousands of kilometers of airborne , collected mainly by NASA and researchers from the UK and Germany over several decades, to piece together the landscape lying beneath the ice sheet that covers most of Greenland and obscures it from view.

At certain frequencies, ice is transparent to which can travel through the ice and bounce off the bedrock underneath. By analysing all the radar data in a consistent way the team discovered a continuous bedrock canyon that extends from almost the centre of the island and ends at its northern extremity in a deep fjord connecting to the Arctic ocean.

3-D view of the subglacial canyon, northwest from central Greenland. Credit: J. Bamber, University Bristol

They believe the canyon plays an important role in transporting sub- produced at the bed from the interior to the edge of the ice sheet and ultimately into the ocean. Even before the presence of the ice sheet, going back at least four million years, the evidence suggests the canyon provided a pathway for water from the interior to the coast and was a major fluvial system.

The research was funded by an EU programme called ice2sea and the UK Natural Environment Research Council (NERC).

Professor David Vaughan, ice2sea co-ordinator based at the British Antarctic Survey in Cambridge said: "A discovery of this nature shows that the Earth has not yet given up all its secrets. A 750km canyon preserved under the ice for millions of years is a breathtaking find in itself, but this research is also important in furthering our understanding of Greenland's past. This area's ice sheet contributes to sea level rise and this work can help us put current changes in context."

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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 and other airborne campaigns, scientists led by a team from the University of Bristol found the canyon runs from near the center of the island northward to the fjord of the Petermann Glacier. Credit: NASA SVS

Some of the data used in the study came from NASA's Operation IceBridge, a six-year mission which is the largest airborne survey of Earth's polar ice ever flown.

Michael Studinger, Operation IceBridge Project Scientist at NASA Goddard Space Flight Center said: "Two things helped lead to this discovery. 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.

"It is quite remarkable that a 750km-long channel the size of parts of the Grand Canyon is discovered in the 21st century below the Greenland Ice Sheet. It shows how little we still know about the bedrock below large continental ice sheets."

Explore further: Lava creeps toward road on Hawaii's Big Island

More information: 'Paleofluvial Mega-Canyon Beneath the Central Greenland Ice Sheet' by Jonathan Bamber, Martin Siegert, Jennifer Griggs, Shawn Marshall and Giorgio Spada, Science, 2013.

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User comments : 11

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tadchem
5 / 5 (3) Aug 29, 2013
Only slightly more detailed than the older map
http://commons.wi...rock.jpg
See figure 6 in the 2011 paper here:
http://www.scienc...11000999
panorama
5 / 5 (3) Aug 29, 2013
Very interesting article, and thanks for the additional info tadchem!
NikFromNYC
1.8 / 5 (16) Aug 29, 2013
Actual link: http://www.scienc...6149/997

Picture filled supplement: http://www.scienc...r-SM.pdf

"Although such associations are known in Antarctica, little consideration has been given to them in Greenland, partly because much of the ice sheet bed is thought to be relatively flat and smooth."

The idea that Greenland ice will suddenly be lubricated enough by a few days of summer surface meltwater to create a sudden collapse has been ridiculed by skeptical claims that the land below is indeed not flat but forms a stabilizing bowl, especially as their Figure S5 shows, the weight of the ice itself accentuates this solid basin.
Q-Star
2.8 / 5 (9) Aug 29, 2013
I wonder if this is one of those predictions of Alfven, Perritt, and Arp? They explained the Grand Canyon in Arizona spot on.
Caliban
3 / 5 (9) Aug 29, 2013
Actual link: http://www.scienc...6149/997

"Although such associations are known in Antarctica, little consideration has been given to them in Greenland, partly because much of the ice sheet bed is thought to be relatively flat and smooth."

The idea that Greenland ice will suddenly be lubricated enough by a few days of summer surface meltwater to create a sudden collapse has been ridiculed by skeptical claims that the land below is indeed not flat but forms a stabilizing bowl, especially as their Figure S5 shows, the weight of the ice itself accentuates this solid basin.


That's right, NikNik from DickCity--

Except for the fact that this wonderful "stabilizing bowl" that you attempt to foist upon us has a number of GREAT, BIG, GAPING NOTCHES in its northern end.

Moron.


NikFromNYC
2.1 / 5 (19) Aug 29, 2013
Caliban is "environmental" activist Clayton Jones, active in letter writing campaigns, such as this anti-nuclear one:
http://nuclearfre...ors.html

...and his exact copy/paste use of it here:
http://pbadupws.n...B512.pdf

For the record, I'm a self-employed product developer and regular night owl with a great affection for Phys.org except for the same madness of crowds insanity that has recently destroyed Scientific American, Discovery and Science News, but here I delve in since I get to finally fight back and call BS on both the deception (such as this visual implication that they are "correcting" *away* the depth of the gravitationally induced bowl just as sea level studies "correct" away the actual *steady* sea level trend and yet still label their graphs "sea level") and call BS on the nature of those who attack skepticism.

Beware NOTCHES!

-=NikNikFromDickCity=-, Ph.D. in carbon chemistry (Columbia/Harvard)
runrig
4 / 5 (9) Aug 29, 2013

The idea that Greenland ice will suddenly be lubricated enough by a few days of summer surface meltwater to create a sudden collapse has been ridiculed by skeptical claims that the land below is indeed not flat but forms a stabilizing bowl, especially as their Figure S5 shows, the weight of the ice itself accentuates this solid basin.

That's right, NikNik from DickCity--
Except for the fact that this wonderful "stabilizing bowl" that you attempt to foist upon us has a number of GREAT, BIG, GAPING NOTCHES in its northern end. Moron.

Stabilising bowl my arse. Ice acts as a fluid on long time scales - just as air on short time scales. Air is not stopped from flowing over mountains. Yes, some gets trapped in valleys but it is entirely free to flow over higher ground. If that were not the case then the ice would split into ravines at high points in the under-rock and we would have a vacuum left in the Atmosphere over the Alps.
NikFromNYC
2 / 5 (16) Aug 29, 2013
runrig, if ice was "fluid" on the time scales involved in policy debate, both Greenland and Antarctica ice masses would be long gone. The skeptical claim I am making is *not* that ice doesn't suffer *plastic* flow, but that alarmists have regularly made headlines with the bizarre disaster scenarios based on the ridiculously speculative idea that huge chunks of Greenland will slide off directly, suddenly lubricated by liquid melt water that seeps down to the rock below. The use of such B movie disaster scenarios by Climatology members reveals that normal Global Warming melting wont in fact create highly profitable disaster scenarios!

The next time I see a glacier join the clouds in the sky I will further consider your own curious theory about ice being air.

-=NikFromNYC=-

P.S. Hey, folks who skim comments, what *sort* of person claims ice is air and also rates comments like "That's right, NikNik from DickCity-...Moron." five stars, all hours of the day, frantically, within minutes?
Shootist
1 / 5 (12) Aug 29, 2013
Gold nuggets the size of Plover's eggs.
runrig
3.3 / 5 (3) Aug 30, 2013
but that alarmists have regularly made headlines with the bizarre disaster scenarios based on the ridiculously speculative idea that huge chunks of Greenland will slide off directly, suddenly lubricated by liquid melt water that seeps down to the rock below. The use of such B movie disaster scenarios by Climatology members reveals that normal Global Warming melting wont in fact create highly profitable disaster scenarios!


Would you like to link to those "disaster scenarios?
I am aware of none - other than of faster glacier outflows spurting to calve, due to lubrication below.
runrig
3.3 / 5 (3) Aug 30, 2013
The next time I see a glacier join the clouds in the sky I will further consider your own curious theory about ice being air.

You were unaware that ice is a fluid as is air.? Both can/are modeled via fluid dynamics.

Greenland ice is generally 2km and up to 3km deep. A "stabilising bowl" 0.8km deep would hardly stabilise that. As water would in a bowl that doesn't come up to half way - it will flow over the sides.... for a long time, before the ridges slow it. Just pointing this out to counter it's use as yet another reflexive insult alluding to so called alarmism.