Artistic expression of large meteorite impact

Oldest Impact Crater on Earth Discovered in Greenland

Article Updated: 23 Dec , 2015

With shifting continents, rain, and wind, finding traces of ancient impact craters on Earth has been, literally, astronomically low. Now, an international team of scientists say they have found a massive impact crater in Greenland a billion years older than other known asteroid impact on Earth.

Scientists found the remains of the giant 100-kilometer (62 mile) wide crater near the Maniitsoq region of West Greenland and they believe it’s three billion years old. The largest and previously oldest known crater is the 300 kilometer-wide Vredefort crater in South Africa. Tipped on its side, the edges of the Maniitsoq crater would extend from the surface of the Earth to the edge of space.

“This single discovery means that we can study the effects of cratering on the Earth nearly a billion years further back in time than was possible before,” according to Dr. Iain McDonald of the School of Earth and Ocean Sciences at Cardiff University, who was part of the team.

Finding the crater wasn’t an easy task. Today, the Moon still shows marks of the massive bombardment that took place between three and four billion years ago. The early Earth, with its greater gravitational attraction, would have experienced even more collisions. But the land around Maniitsoq has been eroded over the eons to expose crust that originally was 25 kilometers (16 miles) below the surface. Effects of the immense shockwave produced on impact penetrated deep into the crust and remain visible.

Evidence at that depth had never been observed before, says McDonald. “The process was rather like a Sherlock Holmes story,” said McDonald. “We eliminated the impossible in terms of any conventional terrestrial processes, and were left with a giant impact as the only explanation for all of the facts.”

Only about 180 impact craters have been discovered on Earth. Around 30 percent of them contain important natural resources, including nickel, gold, oil and natural gas. It was during an exploration of natural resources that evidence for the crater was discovered. “It has taken us nearly three years to convince our peers in the scientific community,” said McDonald. “But the mining industry was far more receptive. A Canadian exploration company has been using the impact model to explore for deposits of nickel and platinum metals at Maniitsoq since the autumn of 2011.”

The international team, led by Adam Garde, a senior research scientist at the Geological Survey of Denmark and Greenland, or GEUS, contains members from Cardiff, Lund University in Sweden, and the Institute of Planetary Science in Moscow. Their work was recently published in the jounal Earth and Planetary Science Letters.

Image caption: An artistic expression of how a large meteorite impact into the sea might have looked in the first second of the impacting. We do not know if the area that was hit was actually covered by water or if there was just a sea nearby. Source: Carsten Egestal Thuesen, GEUS

Map caption: Black circle on map shows the location of the meteorite impact structure near the town Maniitsoq in Greenland.

Read more about the Maniitsoq structure.

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23 Responses

  1. Jens Riggelsen says:

    Adam Garde (mentioned in article) was on danish radio explaining this discovery. One thing struck me: he said in this interview that the asteroid hit earth with a velocity of “20,000 km/s”. This was number was repeated in the news “article” by Danmarks Radio (danish version of BBC).
    Granted, I’m not an expert in either asteroids or geology, but that velocity seems just a bit excessive. I wonder if that’s the velocity they actually expect it had, or if it was just a morning mistake.

    • zkank says:

      I’m certain he meant per hour.
      Meteors hit our atmosphere at slightly higher than that speed, on average (the /hr, that is!)

      • Jens Riggelsen says:

        Like you said, 20,000 km/h is a bit on the low side. 20,000 m/s would make more sense, but would be nice to know for sure.

    • Torbjörn Larsson says:

      I thought it was a typo. Then he may have mentioned the wrong measure, probably meaning m/s for everyday comparison.

      The usual asteroid impactor has ~ 20 km/s relative velocity, since Earth has ~ 30 km/s relative orbital velocity. (Comets may have ~ 40-50 km/s impact velocity, because they also descend the large Sun gravity well and they aren’t necessarily co-rotating with the original planetary disk.)

      • Jens Riggelsen says:

        Yeah, I’m inclined to believe he meant m/s as well. But was hoping someone with access to the original article could clarify, just in case they’re seriously thinking 20,000 km/s.

      • Torbjörn Larsson says:

        Not seriously likely, as it is peer reviewed. An object traveling at ~ 0.1 of light speed would be:

        – “Fascinating” [channeling Spock here], i.e. unheard of as even supernova ejects travels ~ 0.01 of light speed.
        – Way outside the known distribution of impactors (see above) by some factor of 100 – 1000 sigmas.
        – Tear what it hits to pieces I would think. Earth isn’t in pieces.

  2. Olaf2 says:

    Something I have been wondering. Why are there impacts on the poles of the Moon?
    Don’t asteroids tend to move in the plane of the planets and should there not be more craters in that plane of the planets instead of the Moon pole?

    • Skipdallas says:

      The plane of which you speak is not perfectly flat. The Moons diameter is 3474 Km. This is quite a bit smaller that the 1 degree off the ecliptic that the Earth moves through.Meteors and asteroids can and do come in from different angles. Not all collisions are head-on, and even an oblique impact on the moon can leave a huge crater whether this is at the pole or in a more mid-latitude location.

      • Olaf2 says:

        But somehow I would expect that craters would be more elliptical at the poles.

      • Skipdallas says:

        Some craters are elliptical. The point being: There are bodies of varying size and mass out there coming in at different angles and speeds. This is the cause for the wide variance in crater shape, size,and location.

      • Olaf2 says:

        Yes I understand, but I also know that the there should be some statistical distribution of what type of crater corresponds to what area on the moon. e.g. more elliptical near the poles than near the equator (Actually the plane of the planets).

        I do agree that random orbiting objects do exist that will hit the Moon (And Earth) But they are lower in majority and this should be reflected in the craters.

      • Skipdallas says:

        Look at it this way: The Earth has an inclination of its axis 23.5 degrees aprox. The moon also is inclined in its orbit around the Earth. The Earth/moon system is not perfectly on the plane of the ecliptic, (neither are any of the other planets or asteroids some are above, and some are below). Sometimes, due to collisions, bodies are knocked far out of the ecliptic. Then when they are acted upon by close encounters with other bodies, they can come in from and hit at any angle. The Solar system is a messy place and not subject to hard and fast rules as to the distribution,direction of travel,and speed of the small objects within it.

      • Olaf2 says:

        I had to play with Celestia but I see your point now. The plane of the Moon’s orbit is not the same as the Plane of Earth’s orbit.

      • Torbjörn Larsson says:

        No, that is a misconception. Craters form as ~ 20 times larger than the hypervelocity impactor (i.e. fast enough to launch shock waves in rocks, as they go ~ 10 times faster than speed of sound in minerals) because of energy considerations more than momenta.

        Only very glancing hits leaves a somewhat elliptical scar. And if the impactor is roughly as large as the curvature of the “impactee”, all odds are out – you have to make a specific model. I.e. the Aitkens basin and the Borealis basin.

    • And our solar system is tilted almost 90 degrees from the galactic level, too. Stuff on a galactic level can hit in the poles, too.

    • Torbjörn Larsson says:

      The Moon orientation is an argued topic. There are theories of a bulge close to Earth, or a diapir centered on the backside, which have swung the Moon to its orientation in later days:

      “So why is the maria-side facing us, while the crater-side faces away? Is it just a coincidence?

      Researchers from the California Institute of Technology think that
      it’s not about luck at all, but the way the Moon’s rotation slowed down
      after its formation. Oded Aharonson, a professor of planetary science at
      Caltech, and his team created a simulation that calculated how the
      rotation of the Moon slowed down after its formation.

      In any case, remember that Mars have a likely similar glancing hit on its North pole (Ellyseum, I think). It is not uncommon.

      Although the Moon looks like a sphere, it actually has a slight
      bulge. And billions of years ago, when the Moon was rotating much more
      quickly, showing its entire surface to the inhabitants of Earth, the
      Earth’s gravity tugged at this bulge with each rotation, slowing it down
      slightly each time until the Moon’s rotation was completely stopped
      from our perspective.”

      I dunno how much wobble was dampened out, but it, as well as the momenta from impacts, would have mattered.

      • Olaf2 says:

        One of the things I recently realized is that the Moon’s pole is orthogonal to its orbit plane. Earth is not.

      • Peter Croft says:

        a diapir centered on the backside… Yes, diapers do tend to be centred on the backside 😉 Thank goodness.

      • Torbjörn Larsson says:

        Unless its a stomach-throat “hot mass upwelling”. No diapers for those. =D

        I believe it is the lower density expected that would make it face the backside, as opposed to a bulge mascon.

        I favor the diapir, since it predicts the Moon anomalies by its wandering and freezing in.

        And it would confirm the mantle convection model diapirs that predicts the onset of plate tectonic. However if not I hear the ISS can finally be used to calibrate such models. It isn’t a crucial phenomena anymore.

  3. Torbjörn Larsson says:

    This is naturally very interesting from an astrobiology perspective.

    We have many evidences that life survives such impactors easily.

    Mojzsis et al shows how realistic models of impactors on a ocean/crust biosphere have monocellular life surviving any feasible amount of impact rate up to and orders above the Late Heavy Bombardment (LHB). Cells proliferate and spread faster than the impactors can keep up sterilizing. Life is a plague on a planet. [“Microbial habitability of the Hadean Earth during the late heavy bombardment“, Oleg Abramov & Stephen J. Mojzsis, Nature 2009.]

    Even complex multicellular life can survive crust busters straight away, instead of having to restart with eukaryotes. The Goldilock zone for surviving ocean vaporizing is ~ 1 km down, where we now have found nematodes.

    This is likely confirmed by this ~ 3.0 Ga bp (billion years before present) impactor on Greenland, the oldest impactor known after Vredesfort and Sudbury ~ 2 Ga bp. It likely confirms the theory of a Late, Late Tail to the LHB, where they have found 7 (IIRC) large ejecta fields in the record after the LHB @ 4 – 3 Ga bp but no impact scars until now. (Good presentation of Bottke here.)

    The impact formation diameter is ~ 500 km, would have been 1000 km on the Moon but dug deep into Earth. It likely busted the crust since they tell of 800 Celsius environment in the bottom. Anything over 500 Celsius and you have (to my knowledge) dug down to the astenosphere, the upper part of the mantle beneath the crust.

    So it may have evaporated the oceans. Life started before that, at least over 3.2 Ga bp where confirmed finds have been found. (The impactor seems precisely dated as these things go.)

    Yet we are here.

  4. Aqua4U says:

    Yeah… this old gal (Gaia) surely has taken some big ‘hits’. A 62 mile wide crater eh? La Luna has a crater near it’s south pole that is 220 miles in diameter! THAT’LL reorient your rotation and orbit – if you’ve got one!

    There are no doubt many other impact sites on Earth that remain to be found. I’ve always suspected the Hudson Bay as one.. and the Puget Sound (Between Port Angeles and the Anacortes Islands) as another possible ancient crater site..

  5. This is amazing. My first thought was to correlate this event with an area in Newfoundland. There is an area, where they think the “Vikings” settled in and it seems that my theories are rejected. Similar to the age of the Sphinx in Egypt. I learned about this area after listening to an audio book about early voyages. I want to think this impact is significant in trying to understand the area of L’Anse aux Meadows. I think this area should now be understood more fully and will provide more insight into this early settled area. I was looking at wikipedia as well about this place and there is a word Medee which led to the naming of this area…it’s interesting to note that this word Medee seems very similar to the word used today Mayday. I’m not sure about the Etymology but this veiwpoint is interesting. I hope somebody is up for the task. C.Moore

    • Typhon1 says:

      Are you suggesting that the Pyramids are the same age as the impact? The impact area is hundreds of miles from where the Vikings landed in Newfoundland so why should it be significant? The derivation of the word ‘Mayday’ is a corruption of the French, M’aide – help me – and used in distress calls or it’s the first day of May and a pagan festival day. So again, where and why should/is there any connection? We’re talking about an impact 3000 million years ago so it can’t have any cultural significance at all.

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