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Huge Canyon Discovered Under Greenland Ice

Posted by timothy on from the earth-the-present-frontier dept.

cold fjord writes with this news, straight from the BBC: "One of the biggest canyons in the world has been found beneath the ice sheet that smothers most of Greenland. The canyon — which is 800km long and up to 800m deep — was carved out by a great river more than four million years ago ... It was discovered by accident as scientists researching climate change mapped Greenland's bedrock by radar. The British Antarctic Survey said it was remarkable to find so huge a geographical feature previously unseen. The hidden valley is longer than the Grand Canyon in Arizona. ... The ice sheet, up to 3km (2 miles) thick, is now so heavy that it makes the island sag in the middle (central Greenland was previously about 500m above sea level, now it is 200m below sea level)."

34 of 137 comments (clear)

  1. So just wondering... by Daetrin · · Score: 4, Interesting

    In theory, if all the ice on Greenland melted, how long would it take Greenland to spring back up again? I'm presuming it wouldn't be instantaneous or even noticeable to a human on Greenland at the time (well, aside from the earthquakes that would almost certainly accompany such an event,) but are we talking years, decades, centuries, or longer?

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    1. Re:So just wondering... by K.+S.+Kyosuke · · Score: 4, Informative

      By "spring up", you mean floating the crust higher on the mantle? I thought that the north of Europe was even now still rising after the last Ice Age, and that's been quite some time.

      --
      Ezekiel 23:20
    2. Re:So just wondering... by necro81 · · Score: 5, Informative

      Centuries to millennia. Geologists are able to measure the ongoing rebound of North America from the retreat of the glaciers from the last ice age.

    3. Re:So just wondering... by Anonymous Coward · · Score: 4, Informative

      Millennia. The post-glacial rebound is still happening in North America from the last ice age, and that was 10,000 years ago. The New Madrid Seismic Zone is still active today, and experts agree that it has the potential to produce another very powerful earthquake.

    4. Re:So just wondering... by Anonymous Coward · · Score: 2, Interesting

      Some places in Sweden are raising with 9mm/year so it could probably be noticed by humans over a lifetime.

    5. Re:So just wondering... by mark-t · · Score: 2

      Why do you figure that the earth will not be inhabitable by humans? Consider that before the last major ice-age, the world was much warmer than it is now....

      --
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    6. Re:So just wondering... by icebike · · Score: 5, Informative

      In theory, if all the ice on Greenland melted, how long would it take Greenland to spring back up again? I'm presuming it wouldn't be instantaneous or even noticeable to a human on Greenland at the time (well, aside from the earthquakes that would almost certainly accompany such an event,) but are we talking years, decades, centuries, or longer?

      It would be noticeable by humans over their life span.

      You see this (in smaller scale) in places in Alaska where receding ice caps and the glaciers that flow from them slowly recede up the valleys and vegetation changes appear in the wake.

      You also see the river flowing from the glaciers cutting deeper channels to the ocean. The glaciers flowed directly to the ocean earlier, now the glacier's nose is several miles upstream. The river channels "grow" high banks as you travel away from the glacier toward the ocean. This is a sign of uplifting land, (there are no longer and deposited soils being laid down in the area, yet the river banks grow steeper, and the river surface is within a few feet of mean high tide over the years.

      Its not much, but you can see it over a period of 30 or 40 years if you are observant. Surveyors can measure it these days (even without GPS), relative to mean high-tide in those places where survey markers were installed decades ago.

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    7. Re:So just wondering... by Tastecicles · · Score: 2

      dunno, but there is a seesaw effect still in play in Western Europe; the most dramatic effect is seen along the length of mainland Britain. While Scotland is still rising after spending a while under a couple miles of ice, the South of England is sinking as it was largely ice-free during the last big freeze. The phenomenon is slow, it's taking a few thousand years for a complete oscillation, but geological evidence suggests that prior to the last ice age, the North Sea was bone dry (being several hundred metres above sea level!). It won't be very many hundreds of years before Loch Ness is physically isolated from the sea at either end and becomes a fully enclosed high saltwater lake!

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    8. Re:So just wondering... by PurpleAlien · · Score: 3, Informative

      High Coast (Sweden) and Kvarken Archipelago (Finland)

      "The geomorphology of the region is largely shaped by the combined processes of glaciation, glacial retreat and the emergence of new land from the sea which continues today at a rate of 0.9 m per century."

      Source: http://whc.unesco.org/en/list/898

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    9. Re:So just wondering... by Anonymous Coward · · Score: 2, Interesting

      in finland Limingan lahti is famous place it has even "bird sighting places" and along the way to bird-tower theres signs where sealevel used to be... its quite remarkable how much land has risen from sea :D

    10. Re:So just wondering... by K.+S.+Kyosuke · · Score: 3, Funny

      The global mean temperature has been flat for 17 years now.

      Now you've shown him! He's so shocked by this that he won't even ask for sources and citations and will simply back out with his tail between his legs!

      --
      Ezekiel 23:20
    11. Re:So just wondering... by RockDoctor · · Score: 2
      There are several exposed fault scarps in northern Sweden and Norway on otherwise polished flat (by the glaciers) landscapes which indicate that some of the isostatic rebound has taken place (almost) instantaneously.

      From http://www.sgu.se/dokument/service_sgu_publ/C836.pdf comes this caption:

      fig. 18. The Parvie fault at Lake Kamasjaure, some 70 km north of Kiruna. The c. 8 m high fault scarp forms steeply overhanging cliffs indicating reverse fault movement. See helicopter for scale.

      The whole publication is worth a quick scan, even if you're not a geologist. Impressive pictures.

      --
      Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
    12. Re:So just wondering... by RockDoctor · · Score: 2
      Sorry, but you're wrong on a number of counts.

      I'm a geologist who has spent most of the last 30 years working in the North Sea, and living and walking in Scotland.

      but geological evidence suggests that prior to the last ice age, the North Sea was bone dry (being several hundred metres above sea level!).

      Most of the North Sea has been a basin of marine deposition for the last 100-odd million years. The last time that the Northern North Sea was emergent was in the late Jurassic with the deposition of the Ness and Tarbert formations of the Brent group (economically hugely important ; there are several "elephant" oil field hosted in these units ; occasionally we see evidence of roots in the sands when we core them, indicating emergence). These were fed sands from the vicinity of Shetland, but the area has been subsiding in pace with sediment deposition since. The sea in this area is now typically over 100m deep.

      There is evidence (blocks of Chalk Group coccolithophore limestone floundered in lava vents in the volcano centres of Arran, Mull, Rum and Skye) that the whole of Scotland was submerged to a depth of dozens to hundreds of metres ("below storm wave base" in technical terms) by 70Myr ago.

      True, in the Southern North Sea the water is shallower, but that is a relatively small area, and to be honest, I count the whole lot ("Doggerland" and all) as just being a temporarily drowned part of the Rhine delta, with the Thames as a tributary of the Rhine which just happens to meet the sea before it runs into the Rhine. When you look at the thousands of metres of relative change of ground level versus sea level implied by those Chalk blocks hundreds of metres above present sea-level, it is hard to care about where the coast line is this million years.

      It won't be very many hundreds of years before Loch Ness is physically isolated from the sea at either end and becomes a fully enclosed high saltwater lake!

      Loch Ness is separated form the sea by around a 10-12m high ridge of bedrock through which the River Ness and Caledonian Canal cut for 10km. I've walked and cycled the canal towpath several times between Inverness town centre and a relative's home in the village of Lochend, at the end of Loch Ness (some Scottish place names are designed to use obfuscating language to confuse people about the areas geography). I've swum in Loch Ness on several occasions and can assure you of three things : it's fucking freezing ; it's fresh water ; and it's still fucking freezing. It's probably several thousand years since Loch Ness was isolated from the sea.

      Oh, and by the way, my relative has seen Nessie, and she's an idiot, therefore it is really really unlikely to exist. (Except as various fakes and frauds designed to rip tourists off, which is quite fine by me ; it's what they exist for.)

      If you think that the other end of Loch Ness is near the sea, then you really need to look at a map. Or spend 3-4 hours cycling from Fort William to Fort Augustus. I really don't recommend cycling from Fort Augustus to Inverness.

      --
      Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
  2. I think I know what it is by 50000BTU_barbecue · · Score: 4, Interesting

    Is it where the Wunderland Treatymaker was test fired?

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    Mostly random stuff.
  3. Al Gore, you're wanted on line 1... by themushroom · · Score: 2

    Now's the time when climate change could do some good... RAISE GREENLAND! Make it green land!

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    Laughter is the Spackle of the Soul.
    1. Re:Al Gore, you're wanted on line 1... by Kjella · · Score: 2

      And only 1031 years after it was named so in order to trick people into immigrating there, better late than never I guess.

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      Live today, because you never know what tomorrow brings
  4. All can be fixed.... by pollarda · · Score: 4, Funny

    With a little global warming one of the world's greatest landmarks could be recovered, the sag in central Greenland would be fixed and a new source of income for Greenland could be tapped as tourists flock to this new "Grand Canyon" to go hiking, fishing, and camping.

    1. Re:All can be fixed.... by Anonymous Coward · · Score: 3, Funny

      Based on my own experience, once there's sagging in the middle it never goes away no much how hard you try to burn off the weight.

  5. More info by cold+fjord · · Score: 3, Informative

    Giant Canyon Discovered Under Greenland Ice Sheet

    While flying over the ice sheet, scientists over the past three decades have measured the depths of the canyon using a radar system that operates at frequencies transparent to radio waves—from around 50 megahertz to 500 megahertz. A pulse of energy is sent down to penetrate through the ice, bounce off the bedrock, and travel back to the radar system. (Also read: "'Shocking' Greenland Ice Melt: Global Warming or Just Heat Wave?")

    'Grand Canyon' of Greenland Discovered Under Ice Sheet

    --
    much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
  6. Science schmience by Alsee · · Score: 3, Funny

    was carved out by a great river more than four million years ago

    More lies straight from the pits of hell.
    Obviously this super-canyon was carved during Noah's flood.
    Another Win for Flood geology!

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    1. Re:Science schmience by cold+fjord · · Score: 3, Funny

      It will be funny till they find Noah's Ark.

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      much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
    2. Re:Science schmience by MightyMartian · · Score: 4, Informative

      http://www.chem.tufts.edu/science/franksteiger/grandcyn.htm

      AiG's claim was long ago debunked. At this point, the Weekly World News is probably a more reliable source of information than the lying mentally ill nutbars who write for AiG.

      --
      The world's burning. Moped Jesus spotted on I50. Details at 11.
  7. Re:Why is it by Ioldanach · · Score: 5, Informative

    that Greenland is called Green again?

    Propaganda. Erik the Red named it that in 985 AD to get people to colonize it with him.

  8. Accident? by TechyImmigrant · · Score: 3, Insightful

    > It was discovered by accident as scientists researching climate change mapped Greenland's bedrock by radar.

    If you discover a canyon while scanning the bedrock with radar, that isn't an 'accidental' discovery. An accidental discovery is when you're looking for a dropped contact lens and come across a canyon instead.

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    1. Re:Accident? by TechyImmigrant · · Score: 2

      This year I accidentally arranged 100,000ish logic gates into a functioning circuit for use in microprocessor products made by my employer, by using the design tools and design processes available to me.

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      I should use this sig to advertise my book ISBN-13 : 978-1501515132.
    2. Re:Accident? by LynnwoodRooster · · Score: 2

      This year I accidentally arranged 100,000ish logic gates into a functioning circuit for use in microprocessor products made by my employer, by using the design tools and design processes available to me.

      Quick, buy a lottery ticket! Your luck may run out!

      --
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  9. How accurate is the sea level rise figure? by Ioldanach · · Score: 2, Interesting
    "If the Greenland ice sheet melts completely it will raise global sea level by 7 metres and swamp many major cities" (article)

    Does this account for what would happen when Greenland floats back up?

    1. Re:How accurate is the sea level rise figure? by Ioldanach · · Score: 2

      If an area the size of Greenland is depressed 300 meters, I'd wonder if it is deformation of the Earth's crust and the whole thing could be pushed back up by internal pressures when the weight is gone. Not assuming anything, just wondering if that could happen and what the impact on sea levels would be if it did.

    2. Re:How accurate is the sea level rise figure? by mrvan · · Score: 4, Informative

      The sea level rises because the stuff covering Greenland is ice. When it melts it flows into the ocean, raising sea levels. Greenland is around 2M km2, and the ice sheet is around 2km thick, so we're talking about 4 million cubic kilometers of water. Earth has around 361 sq kilometers of water, so spreading the water around the earth gives around 10 meters of ice on each meter of water, or around 9 meters of water. In other words, (1) greenland is huge, and (2) the sea level rise is purely ice flowing into sea and has nothing to do with geological changes.

      Greenland rebounding does absolutely nothing because the "extra" volume is not taken out of the ocean. The water doesn't suddenly jump back up on the land.

      (arctic ice melting does not affect sea levels because the weight of the ice is already displacing water. Antarctic ice and glaciers on land are in the same situation as greenland ice)

    3. Re:How accurate is the sea level rise figure? by ChrisMaple · · Score: 2

      The rock and magma displaced when Greenland sank might (more or less) return from wherever it went. If that area were below the seabed immediately surrounding Greenland, the ocean in that area would get slightly deeper, partially counteracting the increased ocean level (probably about 1/3 in the long term.) However, islands near Greenland might sink along with the ocean floor.

      On the other hand, if the ocean floor near Greenland is relatively still, the closest islands might rise along with Greenland.

      I can imagine other mechanisms and affects, so it's by no means clear what will happen.

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    4. Re:How accurate is the sea level rise figure? by Kjella · · Score: 2

      Not true. You can get shifting in the surrounding rock as things move around, though the effects are complex.

      It's earth's crust rising out of the mantle, if anything the surrounding seabed will rise slightly with it, certainly not the other way around.

      There's also the differences due to the change of the local gravity field; all that ice has a lot of mass and does currently attract plenty of seawater to it.

      Extremely minimal, even if you have 2km sideways pull from the ice there's 6400km of downwards pull towards the center of the earth so water doesn't gather much Heavy mineral deposits or a thick crust directly under the water is different, that adds more compression without trying to counteract the sideways forces.

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  10. Crayon? by steelfood · · Score: 2

    First time I saw the title, I read it as "Huge Crayon Discovered Under Greenland Ice"

    --
    "If a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be."
  11. Giant, ancient river delta means lots of oil by Anonymous Coward · · Score: 2, Interesting

    If there is a giant, ancient river bed across Greenland, that means it has a delta where it dumped into the ocean at its discharge end a long time ago. Find that ancient delta and drill for oil "downstream" of it. Petroleum, is primarily formed from zooplankton and algae getting buried under sedimentary rock for ages, and this process happened greatest where ancient river deltas (and even present deltas) are found.

  12. Re:Why is it by dwye · · Score: 2

    No, but they were successful enough to attempt settling Vinland, and to send roughly-yearly lumbering expeditions for a century after the Skralings chased them out. Their surpluses probably went into internal growth until the climate change suddenly made life untenable, there. If they had learned more from the eskimos they might have been able to keep going.