Elevating this from a mention in my previous Newsworthy Items post.
From ScienceNews
Whether the impact is related to a period of cooling called the Younger Dryas is unknown
By Carolyn Gramling 2:00pm, November 14, 2018
There’s something big lurking beneath Greenland’s ice. Using airborne ice-penetrating radar, scientists have discovered a 31-kilometer-wide crater — larger than the city of Paris — buried under as much as 930 meters of ice in northwest Greenland.
The meteorite that slammed into Earth and formed the pit would have been about 1.5 kilometers across, researchers say. That’s large enough to have caused significant environmental damage across the Northern Hemisphere, a team led by glaciologist Kurt Kjær of the University of Copenhagen reports November 14 in Science Advances.
Although the crater has not been dated, data from glacial debris as well as ice-flow simulations suggest that the impact may have happened during the Pleistocene Epoch, between 2.6 million and 11,700 years ago. The discovery could breathe new life into a controversial hypothesis that suggests that an impact about 13,000 years ago triggered a mysterious 1,000-year cold snap known as the Younger Dryas (SN: 7/7/18, p. 18).
Members of the research team first spotted a curiously rounded shape at the edge of Hiawatha Glacier in northwest Greenland in 2015, during a scan of the region by NASA’s Operation IceBridge. The mission uses airborne radar to map the thickness of ice at Earth’s poles. The researchers immediately suspected that the rounded shape represented the edge of a crater, Kjær says.
For a more detailed look, the team hired an aircraft from Germany’s Alfred Wegener Institute that was equipped with ultra-wideband radar, which can send pulses of energy toward the ice at a large number of frequencies. Using data collected from 1997 to 2014 from Operation Icebridge and NASA’s Program for Arctic Regional Climate Assessment, as well as 1,600 kilometers’ worth of data collected in 2016 using the ultra-wideband radar, the team mapped out the inner and outer contours of their target.
The object is almost certainly an impact crater, the researchers say. “It became clear that our idea had been right from the beginning,” Kjær says. What’s more, it is not only the first crater found in Greenland, but also one of the 25 or so largest craters yet spotted on Earth. And it has held its shape beautifully, from its elevated rim to its bowl-shaped depression.
“It’s so conspicuous in the satellite imagery now,” says John Paden, an electrical engineer at the University of Kansas in Lawrence and a member of the team. “There’s not another good explanation.”
On the ground, the team hunted for geochemical and geologic signatures of an asteroid impact within nearby sediments. Sampling from within the crater itself was impossible, as it remains covered by ice. But just beyond the edge of the ice, meltwater from the base of the glacier had, over the years, deposited sediment. The scientists collected a sediment sample from within that glacial outwash and several from just outside of it.
The outwash sample contained several telltale signs of an impact: “shocked” quartz grains with deformed crystal lattices and glassy grains that may represent flash-melted rock. The sample also contained elevated concentrations of certain elements, including nickel, cobalt, platinum and gold, relative to what’s normally found in Earth’s crust. That elemental profile points not only to an asteroid impact, the researchers say, but also suggests that the impactor was a relatively rare iron meteorite.
Read the full article at the source here:
HT/David Hagen, ResourceGuy, Fred Nicol and maybe some I missed.
This is a place to drill down and get in situ samples of the rocks to do dating. Until then, I don’t see how the crater could be dated.
Yes, between 2.6 million and 11,700 years ago is pretty big spread to be matching it to a climate event only 13,000 years ago.. IMHO.
” Kjær’s team found that most ice in Hiawatha is perfectly layered through the past 11,700 years. But in the older, disturbed ice below, the bright reflections disappear. Tracing the deep layers, the team matched the jumble with debris-rich surface ice on Hiawatha’s edge that was previously dated to 12,800 years ago. “It was pretty self-consistent that the ice flow was heavily disturbed at or prior to the Younger Dryas,” MacGregor says.”
Regarding evidence it should be found in nearby ice cores, it has found at one site.
“In 2013, Jacobsen examined an ice core from the center of Greenland, 1000 kilometers away. He was expecting to put the Younger Dryas impact theory to rest by showing that, 12,800 years ago, levels of metals that asteroid impacts tend to spread did not spike. Instead, he found a peak in platinum, similar to ones measured in samples from the crater site. “That suggests a connection to the Younger Dryas right there,” Jacobsen says.
But it is also possible that not much debris would have been kicked up by the impact.
“After seeing a draft of the study, Johnson, who models impacts on icy moons such as Europa and Enceladus, used his code to recreate an asteroid impact on a thick ice sheet. An impact digs a crater with a central peak like the one seen at Hiawatha, he found, but the ice suppresses the spread of rocky debris. “Initial results are that it goes a lot less far,” Johnson says.”
https://www.sciencemag.org/news/2018/11/massive-crater-under-greenland-s-ice-points-climate-altering-impact-time-humans
A massive Platinum Elements Group (PGE) anomaly would be present in every Greenland ice core, particularly Camp Century and NEEM if the Hiawataha impact occured within the last 100,000 years.
A platinum spike in 1 Greenland ice core is not consistent with this crater dating to the Younger Dryas.
We find that the AC/soot and charcoal peaks recorded
at the YD onset are consistent with the YDB
impact hypothesis. These peaks in biomass-burning
proxies are synchronous with peaks in (1) extraterrestrial
Pt deposition, (2) high-temperature, impactrelated
proxies, including Fe-rich spherules, meltglass,
and nanodiamonds, (3) ice-core combustion
aerosols, and (4) climate proxies that mark the abrupt
onset of YD climate change. This collective evidence
makes the YD onset one of the most unusual events
in the entire Quaternary, and a cosmic impact is the
only known event capable…
https://sacredgeometryinternational.com/wp-content/uploads/2018/02/Wolbach-2018-Fire-Part-2-MS.pdf
interesting…Dave Middleton has shredded the YDB impact hypothesis from his geo-background, and I appreciate that, however, it appears this may be a bit of information that supports the work of Randall Carlson. I really wish we could get Randall Carlson and Dave Middleton on Joe Rogan to debate. I think both men are polished, polite, and pursue professional discourse.
A man can dream. And oh by the way to the status quo folks who think Randall is a hack…ok. Even if he got mopped, it would at least provide a very balanced perspective from two very intelligent folks.
And the Comet Research Group: https://cometresearchgroup.org/comets-diamonds-mammoths/
Great news item – how interesting.
Came here to post exactly that. Many thanks C the M.
Gee, a rare iron meteorite.
“Sounds like gold in them thar hills.”
Sure would be nice if the warming would hurry up a bit and make this easier to get to. 😎
The graphic does give the the appearance of Gaia getting a really big owie and putting a cold pack on it. 🤕
In impacts like this, the impactor is usually completely vaporized.
Yes, and there should be ample debris contained in contemporaneous ice deposits all over Greenland and in ocean sediment deposits in the North Atlantic, at least
Did these “researchers” even bother to do the simplest fact-checking against existing core databases?
Not with an iron. Fragile stones yes.
Whether a meteorite breaks-up or vaporizes is proportional to size. It has to penetrate the mass of the atmosphere slowing and heating it. The larger the meteorite, the easier it can do that.
Might need to need to think about that again, that is a fairly large object…
Correct me if I am wrong, but PE — U=-m B or is it U=m g h….20 or so cubic kilometers…that’s a big hit.
It is striking basalt..
And besides the timeframe is huge, that glacier is three million years old, so much rush to prove the comet theory.
I dare say Randall Carlson will be very interested in this
12,800 years ago: https://www.youtube.com/playlist?list=PL4Fgfe69FySJQLSsk83gbZfbp4ZRUfwUm
ha! I just mentioned that. Wouldn’t you enjoy a nice 3.5 hour podcast on Joe Rogan where Dave Middleton and Randall Carlson debate all the relative evidence? I would!
“There’s something big lurking beneath Greenland’s ice. ”
It’s an alien spaceship.
B-Ark crash site.
Too bad there were survivors… 😉
David,
🙂
It’s the “lurking” part…
It’s aliens. They’ve had their raygun ships down there for thousands of years, waiting for the right moment to crack the surface open and let out the Gorebull upon us.
We’re doomed! Doomed, I tell you! Orson was right. Run away! Run away!
News at 10PM EDT or CDT or something.
Real question: since there are two impact craters to the east of Hudson’s Bay, and there is a set of islands in the bay itself, which might indicate a rise after an impact, how come Hudson’s Bay is not considered a giant impact site?
Because there is no evidence there for a giant impact. It’s explained by the weight of ice upon it pressing down on the crust. It rebounds of course but is soon once again buried under an ice sheet again.
Can you explain how the ice in this one 31 mile wide region was so much heavier than all the ice around it?
The article also mentions finding shocked quartz.
Create a YouTube channel and become a famous ufologist and give wild bug- eyed space alien lectures.
Then, bloviate about climate change, become a hero to the hip and cool and get monetized.*
*Any resemblance to an actual living person, was intentional.
the impact may have happened during the Pleistocene Epoch, between 2.6 million and 11,700 years ago. The discovery could breathe new life into a controversial hypothesis that suggests that an impact about 13,000 years ago triggered a mysterious 1,000-year cold snap known as the Younger Dryas (SN: 7/7/18, p. 18).
–
Begs the question of how much melt and what it should have done to ice cores. Must have happened a long, long time ago.
The likelihood this impact is the YD cause is non-existant.
Let me repeat that, It’s not the YD Cause. Yes,
it may have hit Greenland in the last 100K yrs (after the Emian), but the counter evidence is strong it did not hit at 12 Kyr ago.
Although my sense is that you are correct,what counter evidence?
The stratigraphy of the Greenland ice sheet.
Detailed close up from Google Maps.
Curiously, immediately southeast of the proposed crater are two more arcs, suggesting equally circular circumferences. One about the same size and the other a much larger arc.
So perhaps more craters? Or are these all surface artifacts that have nothing to do with any possible craters lying underneath the ice.
I meant “… immediately southwest …”.
Fascinating and I’m glad WUWT posts this sort of news. In the scale of things it shows we have a lot more to keep thinking about than a little bit more of warm weather over the last 150 years or so.
Keep up the good work.
I agree with MCEA!
so where would the equivalent antipodal hot-spot be now?
Right here:-
Antipodal Point
It is highly unlikey that, if this is an impact crater, that it is young enough to have relevance to the Younger Dryas.
The NEEM and Camp Century ice cores would be totally FUBAR in the Pleistocene sections if a large impact occurred so close by ~13 ka. Plus there would be massive PGE anomalies in every Greenland ice core, rather than a couple of minor Pt spikes.
Furthermore, the Younger Dryas “theory” is that a bolide destabilized the Laurentide ice sheet, triggering the cold glacial stadial, wiping out the megafauna and disappearing the Clovis culture. This “impact” didn’t leave a significant mark in the Upper Pleistocene ice, much less destabilize the much smaller Greenland ice sheet.
Do you have a link or two to these “theories”? I am fascinated by the Younger Dryas period and would like to read more.
There have been quite a few WUWT posts on the Younger Dryas impact “theory” (pro and con) and Younger Dryas in general…
https://wattsupwiththat.com/?s=younger+dryas
Thank you!
now see, this is why I want to watch you and Randall Carlson debate on Joe Rogan. I very much enjoy Mr. Carlson, and I’d be ok if he was completely wrong and you could systematically disprove his assertions point by point. I am a fanboy, no doubt, but I think you would provide a non-judgmental, non dismissive attitude, non arrogant approach. I could be wrong, but I’ve read enough of your work Mr. Middleton.
I doubt you have the interest but have you ever reached out to Mr. Carlson (who is the main proponent of the YDB impact theory) to debate this? I mean just completely exhaust all points. Win where you win, concede where you concede? I would pay to see that.
Joe Rogan is cool… Really like him in Here Comes the Boom with Kevin James, Bas Rutten and Mark De La Grot!
I have zero interest in Mr. Carlson. About the ice age flooding in MT/ID/WA his web site has:
“The most powerful of the terminal ice age floods was the complex of events known as the Missoula Flood, although current theory would suggest a much more complex series of floods rather than a single large scale event.”
It has been 45 years since I’ve heard of anyone that thought there was only 1 flood. That guy was 45 years out of date at the time. There were many floods over a long span of time.
The last number I heard was 96, or so, and all agree there were likely more, and -and- there is evidence there was flooding of the same sort in a previous glacial event. We don’t need no stinking asteroid to explain these events.
Here is a link to great photos and information at the Ice Age Floods Institute:
https://iafi.org/
NASA did high speed impact tests on ice in their labs and showed minimal impressions on the underlying surface. Sea rise pulse 1A and 1B were in fact at 12,800 and 11,600 years ago. Global finger print of impact…
https://cosmictusk.com/wp-content/uploads/180315-YD-Did-the-Black-Mat-Impact_Airburst-Reach-the-Antarctic_-Evidence-from-New-Mountain-Near-the-Taylor-Glacier-in-the-Dry-Valley-Mountains.pdf
Paleosols, as long-term recorders of environmental interaction between the lithosphere, the atmo- sphere, and the biosphere, sometimes contain evi- dence of signature events such as cosmic impacts and airbursts, all noted in various locales such as the northern Andes, the Western Alps of Europe, and the Antarctic Dry Valleys, the last highlighted here. In this particular case, investigations of Ant- arctic paleosols with a focus on weathering features led to a realization that the upper horizons of a middle Miocene stratigraphic stack of paleosols served to record evidence of an impact or airburst. Despite the lack of a crater, and considering that meteor ablation or fragment airburst could account for the melted/welded grains imaged in recovered samples, and considering that increased CO2 and NOx concentrations had been recovered in ice cores from the nearby Taylor Ice Dome, all dated to 12.9 ka, the possible correlation of the Ant-828 paleosol sed- iment to the black-mat airburst dated by Kennett et al. (2015) began to appear as more than a mere co- incidence. The data comprising strings of spherules, carbon-coated felsic grains, melted/welded grains of
Maybe not an asteroid – maybe it was multiple comet fragments, like when Jupiter got peppered by Shoemaker-Levy 9. And perhaps there was a catastrophic flood when huge comet fragments hit the ice cap and melted vast amounts of the ice, followed by drastic reductions in global temperatures due to sun blocking debris kicked up by comet fragment impacts and a return to full ice age conditions. The science is not settled on the YD trigger, and I believe comet fragments are an intriguing possibility. By the way, if you haven’t been to the Channeled Scablands you really need to see them in person. I live on the edge of the Scablands in the Methow Valley of Washington and have driven through them many times. You can plainly see the remnants of massive flooding in the Scablands including colossal boulders that were swept like pebbles along with the torrent and huge boulders weighing hundreds of tons that were deposited hundreds of feet above the flood plain on hillsides like in Wenatchee where I grew up. Seeing this firsthand in the field gives a true sense of how immense this event was. Glacial Lake Missoula flooding did happen many times, obviously, but it appears to me that another far bigger event did too, and comet fragment impacts on the ice sheet are a plausible source and trigger for YD cooling.
Clive Best has made a new model for ice age modulation, based upon orbital cycles and dust-ice albedo. Considering that this is a ‘back of the envelope’ model, it looks pretty promising.
http://clivebest.com/blog/?p=8679
Ralph
peddling your stuff in diguise.
Mosh… Pleas don’t quash his enthusiasm… 😉
My comment in the other thread…
https://www.sciencemag.org/news/2018/11/massive-crater-under-greenland-s-ice-points-climate-altering-impact-time-humans
The Younger Dryas impact supposedly destabilized the Laurentide Ice Sheet (about the same size as the East Antarctic Ice Sheet). Hiawatha didn’t even leave a mark on the much smaller Greenland Ice Sheet.
A massive impact 13-14 ka that close to Camp Century would have left a very clear mark in the Late Pleistocene…
Thanks for all the graphics you provide, David. They really make a big difference in understanding these subjects.
nice. After I’m done watching my Notre Dame hopefully finish off the Orangemen, and finish milling some grains for a wonderful bourbon, I’m going to read through this work. I really appreciate your intelligence and attention to details.
I like bourbon… 😉
Some modeling of impacts in ice suggest that the ice compresses the spread of debris.
“…most ice in Hiawatha is perfectly layered through the past 11,700 years. But in the older, disturbed ice below, the bright reflections disappear. Tracing the deep layers, the team matched the jumble with debris-rich surface ice on Hiawatha’s edge that was previously dated to 12,800 years ago
https://www.sciencemag.org/news/2018/11/massive-crater-under-greenland-s-ice-points-climate-altering-impact-time-humans
The basal ice and edges look like this on radar cross sections pretty well everywhere… irrespective of age.
FYI,
Tallbloke also has a good post on this from the 15th.
https://tallbloke.wordpress.com/2018/11/15/greenland-ice-sheet-hides-huge-impact-crater/
What fascinates me is how this demonstrates that the Greenland ice cap is resilient, durable and difficult to damage.
It could be much older than the ice-sheet.
It’s almost certainly older than the Eemian.
And bigger than the Willamette Meteorite…
https://en.wikipedia.org/wiki/Willamette_Meteorite
If it punched through 2-3 kilometers deep of ice at speed. And left a crater 30 ks. ( ? ) across. It would have instantly evaporated an awful lot of the icesheet…That’s an awful lot of added water vapour in the atmosphere…Would that have a longer term warming effect ? As apart from a cooling effect from all the other stuff ejected into the atmosphere
The crater is at the edge of the ice sheeet.
David, any ideas about the cause of the two deep ravines to the S and SE of the crater?
Rivers… Old rivers.
That’s the edge now, but earlier? Hard to know.
It’s not that hard. We know what the elevation of the ice was in the late Pleistocene.
The edge wasn’t much further outboard at the end of the Pleistocene than it is now…
There is quite a bit of estimation going on here. Quite a huge amount.
There always is. The problem is the jumping to the smoking Younger Dryas gun.
Add a dash of Randel Carlson…
From the article regarding the possible connection to the Younger Dryas:
“The ice-penetrating radar data revealed that the crater bowl itself contains several distinct layers of ice. The topmost layer shows a clear, continuous sequence of smaller layers of ice, representing the gradual deposits of snow and ice through the most recent 11,700 years of Earth’s history, known as the Holocene. At the base of that “well-behaved” layer is a distinct, debris-rich layer that has been seen elsewhere in Greenland ice cores, and is thought to represent the Younger Dryas cold period, which spanned from about 12,800 to 11,700 years ago. Beneath that Younger Dryas layer is another large layer — but unlike the Holocene layer, this one is jumbled and rough, with undulating rather than smooth, nearly flat smaller layers”
Elsewhere it is noted that models [eek!} of impact on an ice sheet indicate that the ice would greatly damp the ejection of debris and that ice would remain in the crater. Also noted is that there are other dynamics that could create the jumbled layer.
We will have to wait for drill cores, as with Chicxulub.
Models that indicate that ice would remain in a meteor crater? A meteor impact that vaporizes rock but leaves ice intact?
It ain’t my model, but I assume that the dynamic has something to do with the relative strength of ice to rock. An impactor might easily penetrate the ice with a smaller hole without a large part of the explosive force being created and/or transmitted and then develop that force on impact with the rock beneath.
Similar phenomena happen with blasting rock overlain by soil all the time. Top layer relatively much less disturbed than the broken rock beneath. All you need to do is get the energy below the ice with less damage to the ice layer.
Hardy ice… /sarc
Yeah, I agree tty, there would be a white-hot smoking hole of lava there, certainly no ice. But there’d be a edge of surviving ice somewhere nearby, and eventually that ice would move back to cover the crater (obviously it did at some unknown time).
The basal portion of the Greenland ice sheet “is jumbled and rough, with undulating rather than smooth, nearly flat smaller layers” almost everywhere, irrespective of age, as are the edges… almost everywhere.
https://wattsupwiththat.com/2018/03/22/a-geological-perspective-of-the-greenland-ice-sheet/
An impact big enough to create a 31 km crater at the edge of the ice sheet would have left an unmistakeable mark in every Greenland ice core. The nearest core, Camp Century, has 50,000 years of undisturbed ice.
http://www.iceandclimate.nbi.ku.dk/about_centre/history/
This definitely looks like an impact crater. It just doesn’t even remotely look like a 13 ka impact crater.
50 plus sites on 3 continents below black mat layer have ample impact proxies
Almost every bit of “black mat” evidence is equivocal.
An iron meteorite would leave a huge PGE (Platinum Group Elements) anomaly, not just hints of Pt anomalies here and there. The PGE anomaly would stick out like a sore thumb in every Greenland ice core.
The Pt anomalies and “black mat” evidence might be indicative of an impact somewhere on Earth at about Younger Dryas time.
However, the Younger Dryas impact theory generally revolves around the impact destabilizing the Laurentide ice sheet, causing a meltwater pulse that shuts down thermohaline circulation, triggering the Younger Dryas and causing the extinction of the megafauna and demis of the Clovis culture.
This relatively large impact didn’t leave a discernable mark on the much smaller Greenland ice sheet, much less destabilize it. SO, even if it did occur at Younger Dryas time, it didn’t do anything that could have triggered the Yoinger Dryas.
The suggestions of an impact of some sort, coupled with ancient tales across the world of fire-breathing dragons bringing devastation from the skies, are certainly interesting, but are a long way from meeting any sort of burden of proof. The evidence for enormous and sudden flooding around Montana is impressive, but linking all these events needs more evidence. This crater doesn’t seem to provide it, though hopefully drilling will be funded for its own sake.
“Further studies are needed/send more money, etc” 😉
Keith, those legends are almost certainly more recent. Most likely from the Burckle Crater in the Indian Ocean.
Much more than 50,000, more like 100 000. That is an old diagram with obsolete chronology based on old unreliable radiocarbon dates.
“Paudorf” = MIS 5a c. 75,000 BP
“Brörup” = MIS 5c c. 95,000 BP
The crater is definitely older than the Eemian, probably much older.
It could be much older than 2.6 million years. This is a Precambrian Shield with hard rocks that erode slowly.
The (smaller) Cretaceous Mien crater in Sweden in similar geology is nearly as well preserved.
The maximum age is said to be based on cutting through a river of that age, ergo the river pre-dated the impact. I do not know how solid that data is, but that was the reason.
A river canyon must clearly be older than the ice-sheet, but there is no telling how much older. River canyons in Precambrian Shield areas can be very old. The Carnarvon River Gorge in West Australia is a good example. It is definitely pre-Cretaceous (since there are Cretaceous sediments in the gorge), but nobody knows how much older.
Oumuamua is now accelerating away from the sun. Poor explanations for the potential reasons for its acceleration have been presented. Like this post on the suspected crater but think maybe Oumuamua may have come back to check on the damage done by it the last time it was here on its climatological experiments 🙂
The “circular” depression depicted on the topo-map of northwest Greenland looks to me like it is either an ancient lake bed or the remnant caldera or crater of an ancient volcanic eruption.
What looks to be an extremely deep (350 meters) crater, with pretty much vertical sidewalls and reasonably “flat” bottom surface that is 31 km (19 mi) wide, …… plus what appears to be two (2) extremely deep (350 meters) river channels entering the crater from the south and southeast , ….. doesn’t appear to me to be the result of a meteorite striking the surface, at least not at any time during the current interglacial (post 22k BP).
In that it appears that the bottoms of both the pe se “river channels” and the “crater” are at the same height above SL, then they both must have been created when Greenland was like 90% ice free. Which also negates the inference that said crater was the result of a meteorite strike.
My first thought was that it might be a cirque…
But I think it’s way too big to be a cirque.
If it was a large caldera there would be large quantities of volcanic rocks in the erratics outside the ice edge nearby. There isn’t, so it isn’t a volcano.
I agree that it is much too large for a cirque. Also the surrounding terrain is to flat for cique formation.
A meteor crater is the most likely explanation.
Note that rare volcanic erratics have actually been found further north, showing that there are actually old volcanoes somewhere in North Greenland:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.491.4477&rep=rep1&type=pdf
tty – November 17, 2018 at 10:12 am
Personally, I have a problem with the assumption that a meteorite with a diameter of 1.5 kilometers (0.9 miles) could have struct northwest Greenland at 56+- kilometers from the present day shoreline to “center-of-impact”, ……. with enough explosive force to create a non-curvature crater bottom with a diameter of 31 km (19 mi) wide and a depth of 350 meters (1,148 feet) with its bottom surface @ 100 meters above SL, …… plus, ….. causing two (2) extremely deep fractures of 350 meters (1,148 feet) each, ….. with one being like 30 km (19 mi) in length and the other being like 60 km (38 mi) in length, …… plus the amazing fact that the 60 km long fracture ACTUALLY splits a 750 meters (2,460 feet) high mountain into two sections.
For the time being, I think that I will put the above hypothesis in the same file folder as the …. “Colorado River eroding Grand Canyon hypothesis”.
Interestingly, the ‘river channels’ do not go all the way to the sea. They to to the circular depression, and disappear.
That’s right, ….. which infers the possibility that they are eroded channels that resulted from “quick and turbulent” meltwater from the high mountain glaciers [Hiawatha] covering northwestern Greenland.
If the glacier ice that once covered NYC and Long Island was 1 mile thick, how thick was the glacier ice covering Greenland? And we know from historical accounts that Greenland’s “lowlands” were fairly “ice free” 1,100+ years ago.
I think the “jury” is still out on the cause of that “depression”.
Definitive evidence of impact are shocked quartz, impact rock breccia, melt, and PGEs.
Apparent two of these were identified.
Shocked quartz, at the very least, in outwash water. This is very likely an impact feature.
In lieu of drilling to the crater, what might show up on Ellesmere that could help date it?
A layer of ice with a big PGE anomaly… which should also be in every Greenland ice core.
Rather more than that. A quick check with the Earth Impact Effects Program (https://impact.ese.ic.ac.uk/ImpactEarth/index.html) suggests that an impact of this size would result in an about 3 inches thick fallout layer at Camp Century.
Admittedly that is for a land impact and an ice impact would probably have less fallout. However the impactor would probably also have to be a lot larger to give a crater of the proper size under thick ice, so the net effect might not be that large.
Another thought: would the ice really be “broken up” inside a meteor crater. Studies of Chicxulub, Sudbury and other craters show that the heat in the rocks underneath the crater is sufficient to keep an extensive hydrothermal system running for millenia, so a ice impact would almost certainly result in crater lake, first open and later subglacial like e. g. Grimsvötn. Of course if some hydrothermal areas remain active after other areas have re-frozen the result might look “broken-up”.
Thanks for reviving the wretched zombie hypothesis of the YD impact. No amount of counter evidence and perfectly adequate oceanographic explanation of the YD will kill off this stubborn belief system. Now we’ll have those arguments repeated for the hundredth time.
The YD impact is in the same category as CAGW as it assumes climate is passive, and can only change due to perturbation from outside. As Richard Lindzen argues, this is a profound mistake. Chaotic dynamics of ocean circulation provide for continual fractal variability in climate with or without external forcing. Failure to understand this results in a mindset where every single up or down of the fractal climate wave train requires a specific, separate, external explanation.
It’s as if, scientists observe someone walking along. They try to make sense of this phenomenon. For every one of the hundreds of steps taken, a different mechanism is proposed. No-one realises that each step is actually part of the same process.
While I agree that the YD impact is hogwash I am less than convinced that the the conventional oceanographic explanation is adequate, mostly because the VASTLY greater freshwater pulse at the end of MIS 6 when the West Siberian ice-dammed lake drained apparently did not have any dramatic effect.
Yes I read some articles that explained the whole series of the Antarctic cold reversal, Bolling-Alerod, YD and then Holocene inception based on a big Antarctic ice sheet collapse and delayed reactions to it. But now I understand this big collapse and melt pulse have been called into question.
The meltwater pulse (MWP-1A) happened, but it almost certainly wasn’t Antarctica-sourced and probably had nothing much to do with Bölling/Alleröd/YD.
The most likely explanation for MWP-1A is melting of the saddle area between the Laurentide and Cordilleran icecaps where a fairly small rise in the equilibrum altitude would cause a very large melt.
Dry Falls 10 mile wide 1000 foot deep torrents of ice melt, doesn’t need validation of another impact site…just is running up the score…
The Bolling-Alerod, the warming peak that forms the early bound of the “YD”, was a real phenomenon. It was the last of about 20 similar Dansgaard-Oesgher (DA) micro-interglacial brief warming events that happened regularly throughout the last glacial interval. Each of these was driven by a warming excursion of the AMOC.
The Younger Dryas (YD) by contrast is just a name for nothing. It doesn’t really exist. All it is is the short interval between the last of the DA events during the glacial interval, and interglacial Holocene inception.
The DA events have an explanation – attractor seeking wobble instability during glaciation, driven by positive salinity-downwelling feedback that always drives the AMOC and its fractal variability.
The Holocene interglacial has an explanation as a Milankovitch paced interglacial, starting like all post-MPR interglacials 6500 years after an obliquity peak. No mystery there.
But the YD requires no explanation since there is nothing to explain.
If there was an “anomaly,” it was the warmth of the The Bolling-Alerod.
Since I happen to live near and for many years actually lived on the huge end-moraine barrier formed across Scandinavia by the YD readvance you will have a very hard time convincing me that it doesn’t exist.
That was real of course.
Would there not have been similar glacier re-advances after the other 19 DA events during the last glacial period?
I guess each such cycle would erase the previous one.
Oh yes, there are plenty of end moraines from previous (re)advances. Particularly ones that happened after the LGM. And in Russia there are end moraines from earlier advances, even back to MIS 5d, since these were more extensive than the LGM advance there and not affected by it.
But the YD end moraines are pretty unique for size and scope. They go virtually all around the Scandinavian Icecap and in most areas are much larger than e. g. the LGM moraines. In many areas they still completely dominate the landscape.
Interesting stuff.
What are the dynamics of a meteor impact with deep ice?I have noticed ice behaves very differently to water or dirt when you are trying to remove it.
Does ice moderate the impact effect on the underlying ground?
I’m sure somebody (the military ?) has tested the effect of different materials fired by rail guns at 50,000 Mph, if not, what is the upper limit before the air friction melts/evaporates the projectile.
Depends on the size of the projectile. Small meteorites evaporate before impact, slightly larger ones break up and often cmpletely or mostly evaporate, the large ones survive to impact. How large depends on the type of meteorite.
The full paper is available here: http://advances.sciencemag.org/content/4/11/eaar8173
SI here: http://advances.sciencemag.org/content/advances/suppl/2018/11/09/4.11.eaar8173.DC1/aar8173_SM.pdf
I think the important message is humankind needs a space defense force to stop major impact: https://youtu.be/d2trtPaD5a8
We just need the “best deep core driller in the world”…
Great website on Comets & Blackmat https://cometresearchgroup.org/
There is an excellent chance that the Hiawatha iron impactor is associated with the Cape York meteorite(s), which were discovered and exploited for their iron by the Inuit centuries ago. The Hiawatha Crater and Cape York are only about 200 miles apart (straddling Thule AFB), and the Cape York objects have already been dated to roughly 10,000 BP. (There are 60 tons of Cape York iron on public display in New York and Copenhagen.)
Since It will be many years before the Hiawatha crater itself can be precisely dated, we should proceed with high confidence that the crater is the same age as the Cape York objects. If that turns out to be wrong, then we will know how Hillary Clinton feels.
The impressive thing here isn’t the crater discovered.
It’s the implications of the ultrawide band radar sensor that found this impact’s potential for finding a lot of other such impacts under the ice.