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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)."

8 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 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.

    2. Re:So just wondering... by ianare · · Score: 1, Interesting

      You are describing glacial retreat caused by global warming, which is not the same thing. As temperatures rise, the ice melts and retreats higher in elevation where it is colder. Also as a result of the warming effect, plants are able to take up residence in land formerly occupied by the ice sheet. In areas with permafrost, some of it will melt, leading to sinking and fractures in infrastructure. Climate change can happen very quickly, as we are seeing.

      An example of glacial rebound would be a fishing village in medieval times now being far from the coast, even though sea levels have risen since. Or of a sound being locked by rising land and turned into a lake. Rebound typically is not measurable within the frame of a single lifespan, more like hundreds to thousands of years. We are still experiencing effects from the melting of the last ice age.

    3. 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

  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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  3. 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?

  4. Re:Why is it by Anonymous Coward · · Score: 1, Interesting

    And despite what you've been taught, it was a successful farming colony until the climate cooled and the route north of Great Britain became too hazardous.

  5. 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.