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Crater Beneath the Greenland Ice

A crater roughly the size of the area inside Washington DC’s beltway has been found beneath the Greenland ice. On this, some thoughts, but first, a reminiscence. If you’ve ever driven the Capital Beltway at rush hour, you’ll have some sense of the crater’s size. My own experiences of it have been few, but the most memorable was the afternoon I spent at NASA Goddard Space Flight Center, where Greg Benford was speaking. We had agreed that after his talk, Greg and I would head out for dinner at a local restaurant, the exact venue to be determined later.

It was about 5:00 PM when we were in the GSFC parking lot ready to go, now joined by Gloria Lubkin, editor emerita at Physics Today. With the help of Greg’s nephew Dominic, we had chosen a French restaurant about 10 miles away. The problem: Greg and Gloria were in one car, I was in another, and it was rush hour. An out-of-towner who rarely got to DC, I was not remotely prepared for the beltway under these conditions.

I had no smartphone then, no GPS, and the only recourse was to follow the bumper of Gloria’s car. If I lost Gloria and Greg, I wouldn’t have a clue where to go. I leave it as an exercise for the reader’s imagination what it was like to be in packed lanes of high-speed traffic as night fell trying to stay close enough to the bumper ahead so as not to lose it, while simultaneously ensuring enough distance to avoid a collision. Success seemed doubtful, but we reached the restaurant together, and the meal was a gastronomic and conversational delight.

Image: Ah the Beltway. Now put all this into high-speed motion. Credit: Craig F. Walker/Boston Globe.

Greenland seems a much tamer place. The crater identified here is about 300 meters (1000 feet) deep and over 30 kilometers (19 miles) in diameter. That puts it among the 25 largest impact craters on our planet. Described in the journal Science Advances, the work was led by scientists from the University of Copenhagen’s Centre for GeoGenetics at the Natural History Museum of Denmark. The data feeding this three-year effort came from NASA.

Specifically, NASA’s Operation IceBridge was in play, an airborne mission to study polar ice using ice-penetrating radar, complemented by earlier NASA airborne missions in Greenland. Located at the edge of the ice sheet in northwestern Greenland, the circular depression under Hiawatha Glacier had never been examined, but clear evidence of its existence could be found in satellite imagery from NASA’s Terra and Aqua satellites, which showed a circular pattern.

Image: Radar data from an intensive aerial survey of the Hiawatha crater in May 2016 is shown here in aqua-colored curtains. A blue arrow points to the central peak of the crater. Credit: NASA/Cindy Starr.

Subsequent radar maps made the crater’s dimensions clear. Another Beltway reference is the fact that Joe MacGregor, a NASA glaciologist at Goddard Space Flight Center, designed the later airborne mapping survey, using ice-penetrating radar from the University of Kansas. Says MacGregor:

“Previous radar measurements of Hiawatha Glacier were part of a long-term NASA effort to map Greenland’s changing ice cover. What we really needed to test our hypothesis was a dense and focused radar survey there. The survey exceeded all expectations and imaged the depression in stunning detail: a distinctly circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris — it’s all there.”

You would think that glacial ice would quickly remove all trace of a crater, which is why the crater’s preservation after perhaps three million years is considered so unusual. The impactor was evidently an iron meteorite more than 0,8 kilometers (half a mile) wide. Kurt Kjær (Center for GeoGenetics at the Natural History Museum of Denmark), who is lead author on the study, believes the crater may be even younger, perhaps a remnant of an event that occurred toward the end of the last ice age. That would make it among the youngest craters on Earth.

Image: The Hiawatha impact crater is covered by the Greenland Ice Sheet, which flows just beyond the crater rim, forming a semi-circular edge. Part of this edge (top of photo) and a tongue of ice that breaches the crater’s rim are shown in this photo taken during a NASA Operation IceBridge flight on April 17. Credit: NASA/John Sonntag.

The paper goes into considerable detail on the issue of the crater’s age, which remains approximate. Consider this:

The sum of these tentative age constraints suggests that the Hiawatha impact crater formed during the Pleistocene, as this age is most consistent with inferences from presently available data. An impact before the Pleistocene cannot clearly explain the combination of the relative freshness of the crater’s morphology and the ice sheet’s apparently ongoing equilibration with the presence of the crater. We emphasize that even this broad age estimate remains uncertain and that further investigation of the age of the Hiawatha impact crater is necessary. Regardless of its exact age, based on the size of the Hiawatha impact crater, this impact very likely had significant environmental consequences in the Northern Hemisphere and possibly globally.

In 2016 and 2017, researchers returned to Hiawatha Glacier to map tectonic structures and collect samples of sediments emerging from below through a meltwater channel. Here is Nicolaj Larsen (Aarhus University, Denmark), one of the authors of the study:

“Some of the quartz sand coming from the crater had planar deformation features indicative of a violent impact; this is conclusive evidence that the depression beneath the Hiawatha Glacier is a meteorite crater.”

It’s interesting to speculate on other still undiscovered impact craters under ice. They’re a reminder that the Solar System was once a violent place indeed, as the surface of our Moon indicates. There, of course, the processes of wind and water erosion could not take place, so we see stark evidence of ancient impacts. Our planet likewise had its share even if a cursory glance at the globe shows only a few, and the continuing cataloging of near-Earth objects reminds us that a defense against collisions like these is a good insurance policy for our species.

The paper is Kjær et al, “A large impact crater beneath Hiawatha Glacier in northwest Greenland,” Science Advances Vol. 4, No. 11 (14 Nov. 2018). Full text. NASA has produced a helpful video available here.

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Comments on this entry are closed.

  • Ashley Baldwin November 16, 2018, 15:52

    Yet three separate Discovery programme submissions for the NEOCAM near Earth Object detection satellite telescope were rejected in 2006, 2010 and 2015 . In 2015 NASA also withdrew funding support for the similar B612 Foundation’s Sentinel satellite which would have orbited near Venus and charted up to 90% of 140 m and larger NEOs over a six year period. The sooner one of these schemes come to fruition , the better.

  • Bruce D. Mayfield November 16, 2018, 16:46

    This reminds me of a visit to Meteor Crater in Arizona. That mile wide hole pales in comparison to this Greenland crater of course, but it helps to picture the 1/2 mile size of the impactor.

  • wdk November 16, 2018, 19:08

    Could this be coincidental?

    A description on line of ice cores and their age:

    Ice cores are drilled in glaciers and on ice sheets on all of Earth’s continents. Most ice cores, however, come from Antarctica and Greenland, where the longest ice cores extend to 3 km—over 2 miles—or more in depth. Ice cores from the cold interior regions of polar ice sheets provide exceptionally well-preserved and detailed climate records. This is because the lack of melt at these locations does not corrupt the record of trapped gases or blur the record of other impurities. The oldest continuous ice core records extend to 130,000 years in Greenland, and 800,000 years in Antarctica.

  • Rob Flores November 16, 2018, 20:59

    I believe a natural history writer many years ago posited that there
    is something wrong with the ecological density and/or maturity of North America and this was not entirely due to Isolation from the other continents.
    What is the effect of such a mountain landing at a high lattitude?
    An impactor at that high latitude will have it’s debris cloud mostly carried off by the north polar wind belt{polar Easterlies} it will eventually move toward the Westerlies at 60deg. But since these polar winds are very mild it’s possible that the impact debris settles more at the northern latitudes than a mid latitude impact which would tend to scatter the debris over a much wider area due to strong air currents [see jet stream].
    Such a high latitude debris cloud could devastate the upper northern hemisphere, But note Africa is spared, and asia+Europe as a massive continent has “reserves” of fauna to reclaim damaged habitats, North America would fare poorer than the rest.
    [South America was not yet joined to south america 3 mya, and there is a climate barrier in Temperate, dessert, jungle, dessert,Temperate type of north-south migration route as Mr J. Diamond has posited]

  • J. Jason Wentworth November 17, 2018, 2:31

    The Greenland impact crater discovery was covered prominently on our local news today in Fairbanks, partly because a team from the UAF–University of Alaska Fairbanks–was directly involved.

  • Michael C. Fidler November 17, 2018, 10:13

    That would suggest that the impact happened sometime before the end of the Pleistocene epoch around 11,700 years ago.

    World-changing event?
    The scientists also don’t currently have enough information to assign an age to the proposed impact crater, but based on their analysis, they have suggested bookends for the date of the event. Given the structure of the rock and ice that can be “read” with radar, the team believes that the glacier was in place at the time of the strike, and that the impact punched a hole in the ice and resulted in a significant amount of melting and refreezing. That would suggest that the impact happened sometime before the end of the Pleistocene epoch around 11,700 years ago.

    “It’s likely quite young, geologically speaking,” MacGregor says. “It’s likely less than three million years old and possibly as young as 12,000 to 15,000 years old.”

    If the discovery holds, the Hiawatha Crater could therefore be a tantalizing new piece of evidence for a very controversial idea. Called the Younger Dryas impact hypothesis, the notion is that some kind of large impact occurred in northern North America about 10,900 to 12,900 years ago, during the Younger Dryas Ice Age. This impact, the idea goes, caused massive wildfires across much of the continent that in turn led to the extinction of many of the large Ice Age mammals, like mammoths and mastodons, as well as the human Clovis culture.

    One big problem with this hypothesis has long been the lack of a suitably large impact crater. If it’s real and the dates match up, the Hiawatha Crater could be a plausible explanation, MacGregor says: “It’s a very speculative idea, but if this does turn out to be [the link], it would have had an outsize impact on human history.”

    https://www.nationalgeographic.com/science/2018/11/impact-crater-found-under-hiawatha-glacier-greenland-ice/

    I think we may have found one of the impacts that resulted in the great flood! ;-}

    Maybe a double whammy from a binary asteroid!!!

    https://www.google.com/maps/place/Greenland+ice+sheet/@78.7511704,-66.6075739,34824m/data=!3m1!1e3!4m5!3m4!1s0x4fa997f6d9409b9f:0x5eefac28e84efb0d!8m2!3d76.7!4d-41.2

    https://en.wikipedia.org/wiki/Younger_Dryas#/media/File:Younger_Dryas_and_Air_Temperature_Changes.jpg

    Timing of retreat of the North American Ice Sheets, beginning ~ 18 ka, ending around 6 ka, lasting 12,000 years. And of course, Greenland is still melting.
    http://web.sonoma.edu/users/f/freidel/global/fig%20113.2.JPG

    http://web.sonoma.edu/users/f/freidel/global/372Chapt13Deglaciation.htm

    So when this impact took place the glacier ice was at least a mile thick and still covered North America down to the great lakes!

    • Andrew November 18, 2018, 17:50

      Michael –

      Maybe you were being facetious about the Great Flood, but there are people who have argued that the flood stories are a culture memory of floods caused by a Younger Dryas comet impact in the northern hemisphere. Of course, one of the biggest weaknesses of that argument has been the lack of an impact basin…

      Any idea if an iron impactor could also cause such widespread flooding (not being a frozen ball of ice)? I see that folks leaving comments on this page seem to think that it could, but I am reading other sources that claim an impactor < 1 mi in diameter would only be a relatively local, and not global, phenomenon.

      • Michael C. Fidler November 18, 2018, 23:25

        No not facetious but there is plenty of evidence of impacts causing major changes in the earth’s climate. Ice sheets covering 1/3 to 1/2 of the earth and mostly oceans covering the rest leave little room for solid remnants of craters. Like I have said before more studies of what large impacts in the ocean’s abyss and the deep ice of the last ice age would have on the earth need to be done. How would these catastrophes leave their fossil imprint in and on the earth plus the cultural impact on the human race. Many cultures have ancient flood myths that speak of the same devastation that took place in the biblical flood. The big difference is that a large iron asteroid or two would be much more devastating than a comet. So I believe it may be coming out fairly quickly if this is the cause of the Younger Dryas. It also appears that Gobekli Tepe was, among other things, an observatory for monitoring the night sky as where many other ancient stone age temples.

        https://www.newscientist.com/article/2128512-ancient-carvings-show-comet-hit-earth-and-triggered-mini-ice-age/

        What I find interesting is that many ancient cultures used stele or ancient stelae monuments to mark historically and astronomically important information. Look at the similarity of Gobekli Tepe to Stonehenge and the significance to death and burial as in gravestones. The Stele could be the marker used for the millions that died after a great impact and the resulting flood.

        • Andrew November 21, 2018, 15:56

          Thanks for the link…the primary research paper that the New Scientist article cites is very interesting, indeed.

          Kjaer et al. seem convinced that the crater is the result of an iron asteroid, however. Any idea how this would lend support to the comet impact hypothesis?

        • Adam November 23, 2018, 19:25

          The current Ice Age, which began in the Pliocene, might have resulted from a case of True Polar Wander, where the rotational axis of the Earth shifted. Astrobiology Mag reports on it:
          ‘TRUE POLAR WANDER’ MAY HAVE CAUSED ICE AGE
          I have to wonder if the wander wasn’t caused by another impact back then, though Earth isn’t an inert object and is quite able to move its own axis of rotation.

  • don wilkins November 17, 2018, 11:09

    Since the gear is integrated and available wouldn’t a scan of Antarctica be of interest?

  • Alex Tolley November 17, 2018, 16:10

    If the meteor was metallic, wouldn’t there be some magnetic anomaly detectable?

    Even though the ice sheets prevented finding impact ejecta in the Northern hemisphere continents, wouldn’t this ejecta be detectable in the ocean sediments? Oceanic cores might be reexamined to look for the matching ejecta and provide a better age estimate.

    • Bruce D. Mayfield November 18, 2018, 18:13

      Since this crater is in northwestern Greenland shouldn’t there also be ice core evidence from points further south allowing the impact to be dated?

      • Alex Tolley November 19, 2018, 13:12

        See wdk and Fidler’s responses down thread. Also, if the impact was older than the ice sheets, then the cores would have nothing to record.

        • Bruce D. Mayfield November 19, 2018, 18:22

          Right, except for at the rock level under the ice inside the crater itself, as others have also called for. Should show some age-able shocked earth rocks and perhaps meteorite fragments as well.

  • wdk November 18, 2018, 1:59

    In the article and the comments above, there seem to be at least two hypotheses offered for when the impact event occurred: about 100,000 – 200,000 years ago and 12,000 or so years ago. While I am inclined to favor the older estimates, I do think that there are some interesting “signals” in the geological record around 12,000 years ago. I am not sure how they are all tied together – if at all. For example, the Eastern Washington channeled Scablands and the flooding of the Black Sea basin appear to have occurred roughly at the same time. These floods might be related – or they might not.

    But the testimony of Antarctic and Greenland cores ought to have something to say about this. Usually I read of them in the context of what they say about carbon dioxide levels in ancient times, but they should also tell us something about eras where deposition of dust significantly changes. The whole slate should blank out if there is a thaw and convective mixing. Just the fact that Antarctic records date back further seems an argument in behalf of a Greenland erasure. Which also leads to the question: why should Antarctic records give out close to a million years ago. Another impact or radical thaw?

    If we have ice cores from the Greenland glacier extracted above the 35 kilometer diameter Hiawatha Crater, it should be possible to lay to rest the idea of whether the impact occurred 12 or 200 thousand years ago. If not, it would be a high priority to obtain them.

    Secondly, the Antarctic record which stretches even farther back should have a deposition trace for a cratering event of such a magnitude. Even if it is not the same magnitude as the Upper Cretaceous boundary, it’s a huge event that dwarfs a volcanic explosion like Krakotoa. My suspicion is that most of the Greenland ice sheet would have been disrupted or melted as a result of such an impact – and that the reason there is such a discrepancy in age between maximum ages for samples in Greenland and Antarctica is on account of that is what happened. A twelve thousand year old impact would have to generate an enormous signature in surviving ice cores, if they had survived at all.

    It is possible that the lengthy report in Science Advances might already give us some further clues.

    • Michael C. Fidler November 19, 2018, 9:39

      I think you are correct in that a major melt and then cooling after the atmosphere was loaded with dust and H2O. This could of caused a worldwide disruption of any deposits in the glaciers as the melting would lead to runoff of the dust from the impact.

    • Andrew November 21, 2018, 16:10

      Wouldn’t a complete thawing of the Greenland ice sheet have caused a sudden spike in global sea levels, which would be evident today? Even a partial thawing would cause catastrophic flooding, especially for people living near oceans and rivers…and might be compatible with the relatively slow sea level rise we see at the end of the ice age.

  • Rogerio Penna November 19, 2018, 22:49

    Please, notice that humans always live close to rivers and to the sea. Any sudden sea rise of 1-2 meters would look, from the point of view of 80% of the pre historic human population, as a global flooding.

  • ljk November 20, 2018, 12:24

    4 newly detected asteroids within 1 lunar distance, including second closest of the year.

    Posted by TW on November 19, 2018 in categories Featured articles, Near-Earth Objects

    https://watchers.news/2018/11/19/4-newly-detected-asteroids-within-1ld-november-2018/

  • Sean Robert Meaney November 20, 2018, 22:25

    https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=330&distanceUnits=2&diam=900&diameterUnits=1&pdens=8000&pdens_select=0&vel=51&velocityUnits=1&theta=45&wdepth=&wdepthUnits=1&tdens=2750

    The crater size puts total kill by thermal radiation out to 330 mile radius. The quake, and the wind blast, and the ejecta are further reaching, but at best a light dusting out to a thousand mile radius. It might block out the sun over greenland, and that might be sufficient to create a long and deep winter in the north.

    • Michael C. Fidler November 21, 2018, 11:01

      Sean, I played with this simulator but one problem is the Tsunami. No matter if it was in the mid pacific ocean or NW Greenland it gave the same result. This seems to be a very inaccurate indication of what would be taking place when a 900 meter iron hammer would clobber 10,000 feet of solid ice on top of hard bedrock. I would think NASA needs to run a few projectiles thru it’s meteor cannon at a block of ice…

  • wdk November 21, 2018, 23:04

    Out of my depth on this, of course, but started looking at information about the Greenland ice sheet. Wikipedia as a source indicates that there is identified Greenland ice as old as 1 million years, but the cores have only gone back to 100,000, providing detailed climate data based on gas isotopes, dust, etc. Then checking their sources, leads to some interesting observations about geologic periods.

    “The Greenland Ice Sheet formed in the middle Miocene by coalescence of ice caps and glaciers…
    “There was an intensification of glaciation during the Late Pliocene,…the epoch in the geologic timescale that extends from 5.333 million to 2.58[5] million years BP.”

    Apparently, mountainous “up-rises” on east and west coasts made conditions favorable for accumulation of snow and ice to collect in the interior – to as much as 10,000 ft depth.
    But what you see in most of these descriptions are discussions of how unstable the ice pack would be in the face of a higher global temperature of ~ 3 degrees kelvin, assuming a CO2 greenhouse effect induced by human activity.

    Well, there apparently was a higher global temperature:

    The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene.

    “The global average temperature in the mid-Pliocene (3.3–3 mya) was 2–3 °C higher than today,[11] carbon dioxide levels were the same as today,[12] and global sea level was 25 m higher.[13] The northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma.[14] The formation of an Arctic ice cap is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds.[15] Mid-latitude glaciation was probably underway before the end of the epoch. The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas…”
    http://www.giss.nasa.gov:80/research/features/pliocene/page3.html

    “At present, our results do not support the suggestion that Pliocene warming was caused by carbon dioxide increase since such changes are not consistent with the SST distributions derived from deep sea cores. There is evidence that changes in ocean circulation and the amount of heat oceans transport may be one potential cause of the warming.

    “Still, investigators have found evidence that minor increases in CO2 (up to 380 ppm) did occur in the Pliocene. This causes us to wonder whether it is possible that an, climate feedback, as of yet unknown, associated with small increases in CO2, could lead to the larger changes seen in the ocean circulation?”

    ——
    So, sorting through that and knowing now that there is a 30 kilometer wide crater under the ice pack, assuming it is older than a million years old, it might have struck while there was no ice or struck ice. But in either case, it was likely to have been responsible for a warming event. The discussions about ice pack retreat indicate that polar regions would experience a feedback effect in their loss of reflectivity. Consequently, it might take a while to get the ice pack back – and then there would be consequences elsewhere too: ocean circulation, sea level and forestation on other continents…

  • Michael C. Fidler November 21, 2018, 23:11

    Actually that is not correct, see this:

    Deglaciation occurred in two pulses, interrupted by a cold period, the Younger Dryas, during which melting continued at a much slower pace.

    http://web.sonoma.edu/users/f/freidel/global/fig%2013.4.JPG

    What is interesting is not one but two meltwater pulses, the 0ne around 14,500 years ago being some 48 meters (160 Feet) and at 11,500 ago being some 35 meters (120 Feet). We may be looking at two different impacts in a very short period of 3000 years, this could be caused by a comet or asteroid that was torn apart by earth’s gravity well or one of the other planets. The Comet Shoemaker–Levy 9 that was ripped apart by Jupiter in 1992 with an impact of 21 separate objects on Jupiter on July 1994. The earth could of been in the path of such a iron asteroid’sorbit that was ripped apart by Jupiter, since it is the mother of comet and asteroid families. So Satan’s hammer could of struck twice 3000 years apart but from the same source.

    Fascinating that the mythical THOR’S HAMMER was supposedly made from a meteorite iron. Take a look at this!!!

    http://sciencenordic.com/greenlands-iron-age-came-space

    https://www.dailymail.co.uk/sciencetech/article-2909898/Before-iron-Greenland-METEORITE-Age-Prehistoric-Eskimos-mined-giant-space-rocks-make-tools-weapons.html

    And the famous Thule early warning for ICBM site is not far from the crater!

    https://www.google.com/maps/place/Thule+Air+Base/@76.544234,-68.6517951,11609m/data=!3m1!1e3!4m5!3m4!1s0x4e3625d144890499:0x93ea504cce2710ae!8m2!3d76.5333076!4d-68.6999101

    So the impacts may have a very, very long mythological history, up to the Mecca iron meteorite worshiped by the Muslim’s!

    ‘True polar wander’ may have caused ice age!

    https://phys.org/news/2018-11-true-polar-ice-age.html

    But getting back down to earth, or the edge of the flat earth, or Immanuel Velikovsky Earth. ;-})

    Did the Frozen Mammoths Die in the Flood or in the Ice Age?

    https://www.icr.org/article/did-frozen-mammoths-die-flood-or-ice-age

    • Bruce D. Mayfield November 22, 2018, 15:39

      The range of your sources are quite broad Michael. I too endeavor to maintain an open mind about things, figuring that to find the truth facts mustn’t be ignored. Myths can have a kernel of truth to them that got the story started, as it where.

      But, one must also be cautious of those who seek to garner a following for personal gain. I’m sure I’m not telling you anything you haven’t already observed though.

      mayfield.bruced@gmail.com

  • Michael Fidler November 22, 2018, 1:33

    The problem is any evidence is under water. The whole area from Thailand to Bali in the southeast Asia region was above sea level in the last ice age. There are many examples of ancient structures existing on the now submerged continental shelves around the world. Plus the many myths to the same. Just as the ice had covered this crater the oceans have devoured any evidence of a great flood. 20,000 years ago the earth was a completely different world from the one we know today. Happy Thanksgiving to all!

  • wdk November 22, 2018, 11:23

    Michael Fidler,
    It looks to me like we are examining two different hypotheses: circa a million or more years ago (me) and about 12,000 years ago (you). But I need to look at the references you sent.
    And happy Thanksgiving as well! After all, we can be thankful we weren’t at ground zero – whenever it was.

    • Michael Fidler November 22, 2018, 20:23

      Sorry, but was suppose to be comment to Andrew. My computer burped and it was sent to wrong location. But now that I’ve your attention any way to date the iron being found around Greenland?

      • wdk November 23, 2018, 20:12

        MF,
        Checked the Nordic Science (U. of Oslo) website you provided above. Very interesting.
        There was also another link at the bottom of the article that throws some light on the quetion you raised. It was an account of other Greenland ice pack meteorites, shergottites associated with Mars. What interesting there is that it relates that there are several ages identified:
        The original age of the material knocked loose from a crater ( ~4 billion years ago), the transit time in space ( about 3 million years back from present) and the arrival around 1865. And, unfortunately, that part was nailed by observers.
        The other segments of shergottite ages were based on isotope ratios or evidence of exposure to galactic cosmic rays in transit from Mars to Earth. As to what stop watch is used for an exposed iron meteorite, I don’t know. I guess rust could be some measure and if there is any way organic build-up would allow carbon-14 to give an estimate.

        By coincidence, this week’s Science mentions a drop in -in Africa a couple of million years ago due either to climate change or attack by our very remote ancestors ( “Plio-Pleistocene decline of Africanmegaherbivores: No evidencefor ancient hominin impacts” ). There was a chart of atmospheric CO2 variations which provided some sharp spikes ( at 2.2 and 3.8 million years ago. Overall it exhibited a downward trend from a peak concentration of CO2 to about 400 ( 300 to 475 oscillatory )parts per million about 5- 6 million years ago to
        a pre-industrial value around 200. My guess, if of any value, would be that the 2.2 and 3.8 spikes could be associated with an event in Greenland, but like the article, hypothesis to base an investigation on.

        • Michael C. Fidler November 24, 2018, 23:34

          Ok, CO2 is the outcome of either the parent body (asteroid) or the underlying rock of the impact crater. Both of which have low carbon amounts in this case plus the overlying 2 mile layer of thick ice. So would this case a jump in H2O in the atmosphere and if the impact was hot enough to separate the H and O, some sort of anomaly from that? Would the major result be enough to cause large scale rain if enough water and dust was ejected from the impact? This would cause the subsequent cooling that slowed the end of the ice age in the Younger Dryas period. The big question is could the impact cause the large melt from that period also?
          Supplementary material for this article is available at :
          http://advances.sciencemag.org/highwire/filestream/208794/field_highwire_adjunct_files/5/aar8173_SM.pdf
          See these slides in supplemnent:
          Fig. S1. Bedrock type and lineations across Inglefield Land near Hiawatha Glacier.

          Fig. S2. Terminus history of Hiawatha Glacier and its transition from a floating to a grounded tongue with a proglacial floodplain.

          Fig. S3. CI-chondrite–normalized metal patterns for glaciofluvial sediment samples compared to upper continental crust.

          Fig. S4. Model mixtures of crust with mass proportions of various meteorites.

          • wdk November 25, 2018, 14:19

            MF,
            This is great raw data, plus the closest images of the place I’ve seen so far.
            But what does not leap out at me is how these supplemental charts give an indication of when the event might have occurred. Admittedly some glaciers have been around for thousands of years, some orders of magnitude more. You can’t fool mother nature, but she can fool me.

            On the subject of CO2: In the current debate about climate change, you can see attributions for sinks and sources in plants and combustion. Assuming a pre-historic rise in CO2, it might be attributed to forest fires; the rebound might be from forest growth. The latter is suggested for the Mini-Ice Age, a re-forestration of the New World after an earlier period of cultivation falling into neglect after disruption of civilizations by widespread fatal epidemics or wars. Fires, dust and ice melt from the impact would have a more pervasive effect than the Mini Ice Age, of course. Disturbances 12,000 years ago could be related to them, of course, but we also have a wider stretch of geologic history that could swallow up such an enormous event more easily. And it’s not really clear ( at least to me) whether the impact occurred when there was a Greenland ice cover there or during an interval when there was not.

            • Michael C. Fidler November 25, 2018, 23:27

              That’s the problem, the ice age was still in full swing and most of north america was covered in deep ice down past the great lakes. Not much to burn and the bedrock that was exposed by the impact was not high in carbon either. The other changes are the end of the megafauna and the disappearance of the Clovis culture all which point to a major climatic upheaval. This has all been discussed in the Younger Dryas impact hypothesis:
              https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis
              Since this impact is much further north then any that was talked about in that case we need to look at how this impact fits into the data that was given for the Younger Dryas impact hypothesis. I think half the work on the puzzle is already done and with just a few more pieces the whole picture will become clear. My question to all the impact researcher’s is exactly what happens to the ice when compressed to mega pressures from a huge iron hammer hitting it at 12 miles a second…

  • Michael C. Fidler November 27, 2018, 17:50

    Prehistoric cave art suggests ancient use of complex astronomy.

    “Some of the world’s oldest cave paintings have revealed how ancient people had relatively advanced knowledge of astronomy. Animal symbols represent star constellations in the night sky, and are used to mark dates and events such as comet strikes, analysis from the University of Edinburgh suggests.”

    https://www.sciencedaily.com/releases/2018/11/181127111025.htm

    Decoding European Palaeolithic art: Extremely ancient knowledge of precession of the equinoxes.
    Martin B. Sweatman, Alistair Coombs
    (Submitted on 31 May 2018)

    “A consistent interpretation is provided for Neolithic Gobekli Tepe and Catalhoyuk as well as European Palaeolithic cave art. It appears they all display the same method for recording dates based on precession of the equinoxes, with animal symbols representing an ancient zodiac. The same constellations are used today in the West, although some of the zodiacal symbols are different. In particular, the Shaft Scene at Lascaux is found to have a similar meaning to the Vulture Stone at Gobekli Tepe. Both can be viewed as memorials of catastrophic encounters with the Taurid meteor stream, consistent with Clube and Napier’s theory of coherent catastrophism. The date of the likely comet strike recorded at Lascaux is 15,150 BC to within 200 years, corresponding closely to the onset of a climate event recorded in a Greenland ice core. A survey of radiocarbon dates from Chauvet and other Palaeolithic caves is consistent with this zodiacal interpretation, with a very high level of statistical significance. Finally, the Lion Man of Hohlenstein-Stadel, circa 38,000 BC, is also consistent with this interpretation, indicating this knowledge is extremely ancient and was widespread.”

    https://arxiv.org/abs/1806.00046v1

    Comets and the Bronze Age Collapse.

    https://web.archive.org/web/20011030070727/http://abob.libs.uga.edu:80/bobk/bronze.html

    Comet Encke.

    http://www.fallofathousandsuns.com/comet-encke.html

    Exploring abrupt climate change induced by comets and asteroids during human history.

    https://cosmictusk.com/cosmic-tusk-interview-1-dr-bill-napier/

    From the looks of it a super comet orbit was changed about 20,000 years ago. It was part of the Jupiter family of comets and after the new orbit became the shortest period comet we now know as Comet Encke. This comet at that time was much larger and broke up into smaller pieces and created the many Taurid fireball streams. This is probably the origin of the Greenland impact and is believed to be the cause of the Tunguska impact in 1908.

    Coherent Catastrophism.

    https://people.well.com/user/mcdee/Catastrophe.html

  • Michael C. Fidler November 28, 2018, 20:42

    Cosmic Airburst May Have Wiped Out Part of the Middle East 3,700 Years Ago.

    Unusual pottery
    “Among the evidence that the scientists uncovered for the airburst are 3,700-year-old pieces of pottery from Tall el-Hammam that have an unusual appearance. The surface of the pottery had been vitrified (turned to glass). The temperature was also so high that pieces of zircon within the pottery turned into gas — something that requires a temperature of more than 7,230 degrees Fahrenheit (4,000 degrees Celsius), said Phillip Silvia, a field archaeologist and supervisor with the Tall el-Hammam Excavation Project. However, the heat, while powerful, did not last long enough to burn through entire pottery pieces, leaving parts of the pottery beneath the surface relatively unscathed.”

    https://www.livescience.com/64179-ancient-cosmic-airburst-middle-east.html

    ‘Fire and Brimstone’ that Destroyed Biblical Sodom Matches Findings of Cosmic Catastrophe 3,700 Years Ago.

    https://www.ancient-origins.net/news-history-archaeology/sodom-meteor-0011030

    Now imagine even larger superbolide airburst happening over the glaciers of the ice ages.

    List of meteor air bursts.

    https://en.wikipedia.org/wiki/List_of_meteor_air_bursts

    Take a look at the first table – these happen much more often the impacts and the last one in the table happen less the 2000 years apart!
    That type of blast was as powerful as the Castle Bravo H bomb, which was not an airburst.

    “Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of Operation Castle. Detonated on March 1, 1954, the device was the most powerful nuclear device detonated by the United States and its first lithium deuteride fueled thermonuclear weapon.[1][2] Castle Bravo’s yield was 15 megatons of TNT, 2.5 times the predicted 6.0 megatons, due to unforeseen additional reactions involving 7Li,[3] which led to the unexpected radioactive contamination of areas to the east of Bikini Atoll.”

    https://en.wikipedia.org/wiki/Castle_Bravo

    So the need for studies of what these large scale Superbolide airburst over the huge glaciers covering 1/3rd of the northern hemisphere from 10,000 to 3.2 million years ago, what was the effect on human development???