Slashdot Mirror
Earth is Missing a Huge Part of Its Crust. Now We May Know Why. (nationalgeographic.com)
A fifth of Earth's geologic history might have vanished because planet-wide glaciers buried the evidence. From a report: The Grand Canyon is a gigantic geological library, with rocky layers that tell much of the story of Earth's history. Curiously though, a sizeable layer representing anywhere from 250 million years to 1.2 billion years is missing. Known as the Great Unconformity, this massive temporal gap can be found not just in this famous crevasse, but in places all over the world. In one layer, you have the Cambrian period, which started roughly 540 million years ago and left behind sedimentary rocks packed with the fossils of complex, multicellular life. Directly below, you have fossil-free crystalline basement rock, which formed about a billion or more years ago.
So where did all the rock that belongs in between these time periods go? Using multiple lines of evidence, an international team of geoscientists reckons that the thief was Snowball Earth, a hypothesized time when much, if not all, of the planet was covered in ice. According to the team, at intervals within those billion or so years, up to a third of Earth's crust was sawn off by Snowball Earth's roaming glaciers and their erosive capabilities. The resulting sediment was dumped into the slush-covered oceans, where it was then sucked into the mantle by subducting tectonic plates.
Effectively, in many locations, Earth buried the evidence of about a fifth of its geological history, the team argued this week in the Proceedings of the National Academy of Sciences. The notion is elegant but provocative, and the authors themselves predict that some geoscientists will express skepticism. "I think, though, we have extraordinary evidence to support that extraordinary claim," says study leader C. Brenhin Keller, a postdoctoral fellow at the Berkeley Geochronology Center.
So where did all the rock that belongs in between these time periods go? Using multiple lines of evidence, an international team of geoscientists reckons that the thief was Snowball Earth, a hypothesized time when much, if not all, of the planet was covered in ice. According to the team, at intervals within those billion or so years, up to a third of Earth's crust was sawn off by Snowball Earth's roaming glaciers and their erosive capabilities. The resulting sediment was dumped into the slush-covered oceans, where it was then sucked into the mantle by subducting tectonic plates.
Effectively, in many locations, Earth buried the evidence of about a fifth of its geological history, the team argued this week in the Proceedings of the National Academy of Sciences. The notion is elegant but provocative, and the authors themselves predict that some geoscientists will express skepticism. "I think, though, we have extraordinary evidence to support that extraordinary claim," says study leader C. Brenhin Keller, a postdoctoral fellow at the Berkeley Geochronology Center.
It's called the moon.
up to a third of Earth's crust was sawn off by Snowball Earth's roaming glaciers and their erosive capabilities.
Let's see, we could worry about the Earth maybe getting a few degrees warmer and having to back away from the ocean a bit.
Or we could worry about ENTIRE CONTINENTS being "sawed off the earth" by glaciers as the rest of us starved because there was nowhere on earth you could grown more than a handful of crops in the icy cold.
Way better in my mind to engineer how to deal with warming - and keep it permanent - rather than let the Earth slide back into yet another long ice age, as it is otherwise bound to do.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
> because glaciers don't "move"
They certainly do. Or at least they can...
https://en.wikipedia.org/wiki/...
And they're pretty effective at scrubbing the underlying terrain.
=Smidge=
They can SHIFT just like anything else sitting on this planet - they don't act like bulldozers.
you exactly where the crust went, and when, and why.
I live in Finland and the movement of the glaciers is clearly visible on rocks here.
> they don't act like bulldozers.
Yes they do. Glaciers can slide for miles, picking up chunks of rock and dragging them along the underlying surface literally scouring the underlying earth like a river of sandpaper. They can dig out valleys, transport the material miles away and dump it. A few million tons of ice sliding around will easily act like a bulldozer. Glacially formed striation and moraines are all over the place.
They are literal rivers of ice; they flow, not just shift.
=Smidge=
I thought this was already known ... Except the glaciers didn't "saw" off the crust (because glaciers don't "move") but pulverized it under their weight as the ice and snow built up and with annual run-off draining the sediment away.
It was previously suspected, not known, that the basement rock was crystallized under the weight of the 2 kilometer thick ice sheets, but there was little evidence this part of the hypothesis was correct, it was just the best fitting piece of the puzzle so far.
The authors of this new puzzle piece both claim it's a better fitting piece and that they have evidence.
If that evidence turns out to be true that would give this explanation a pretty huge leg up over the old guess.
You should start a glacier pressure channel on youtube.
The problem they might encounter with the skeptics is explaining why the missing rock seems to be so uniform all over the globe. Surely the glaciers would be thinner at the equator? The missing rock should not go as far back at the equator as the topical zones, I would think.
Look back up at my post, now look back down, you're on the Internet. Now look back up. I'm a signature.
The poor sods who wrote this paper will be crushed by the Global Warming maniacs.
Not at all. This aligns perfectly with our existing understanding of Earth. Climate changes slowly over periods hundreds of thousands and millions of years.
The problem with global warming is that the climate is changing in a periods of decades. This is a problem because this does not provide the time required for fauna/flora to evolve. As a result of this decreased period, many species are facing extinction.
Anons need not reply. Questions end with a question mark.
All the cool, popular kids have their PB&J sandwiches made with the crust cut off. So Mother Gaia just tried to copy!
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Comment removed based on user account deletion
Why couldn't they get soil from Mars instead? Then again, maybe they did both, and that's why Mars is so puny.
Table-ized A.I.
https://www.livescience.com/62...
Artifacts of human or other industrial civilizations are unlikely to be found on a planet's surface after about 4 million years, said Frank and study co-author Gavin Schmidt, director of NASA's Goddard Institute for Space Studies in New York. For instance, they noted that urban areas currently take up less than 1 percent of Earth's surface, and that complex items, even from early human technology, are very rarely found. A machine as complex as the Antikythera mechanism â" which is considered to be the world's first computer from ancient Greece â" remained unknown until the development of elaborate clocks in RenaissanceEurope.
One may also find it difficult to unearth fossils of any beings who might have lived in industrial civilizations, the scientists added. The fraction of life that gets fossilized is always extremely small: Of all the many dinosaurs that ever lived, for example, only a few thousand nearly complete fossil specimens of the "terrible lizards" have been discovered. Given that the oldest known fossils of Homo sapiens are only about 300,000 years old, there is no certainty that our species might even appear in the fossil record in the long run, they added. [In Images: The Oldest Fossils on Earth]
https://www.nbcnews.com/mach/s...
âoeOur cities cover less than one percent of the surface,â he says. Any comparable cities from an earlier civilization would be easy for modern-day paleontologists to miss. And no one should count on finding a Jurassic iPhone; it wouldn't last millions of years, Gorilla Glass or no.
There is tons of theories that there has been previous intelligent civilizations prior to our own current one. Hell, NASA is even researching it. You are a moron to just activity dismiss this possibility. Both articles I reference note that artifacts would not survive millions of years.
Do I believe this? Not at the moment. But I am not a moron like some posters here that would refuse to acknowledge the possibility, even if a fucking previous intelligent artifact hit them in the head and was dated to 1,000,000 years of age. Fucking idiots
Anonymous comments are as pathetic as the anonymous "sources" that contaminate gutless journalism from the New York Time
"Pedantic much?"
You must be new here. All this site is, is a race to the bottom for who can "well, actually" more microscopically than anyone else.
We should have a reward here for the most misleading topic.
The very linked article itself, and further research about "Great Unconformity" clearly state that this particular unconformity is limited to the Great Canyon GRAND CANYON - THE GREAT UNCONFORMITY and from wikipedia Great Unconformity one can further learn about this "annomaly" together with it's explanation:
Unconformities in general tend to reflect long-term changes in the pattern of the accumulation of sedimentary or igneous strata in low-lying areas (often ocean basins, such as the Gulf of Mexico or the North Sea, but also Bangladesh and much of Brazil), then being uplifted and eroded (such as the ongoing Himalayan orogeny, the older Laramide orogeny of the Rocky Mountains, or much older Appalachian (Alleghanian) and Ouachita orogenies), then subsequently subsiding, eventually to be buried under younger sediments.
We could've avoid all the wide speculations if only the topic was reflecting the content, as "Hi, look what interesting about geology I found - it's old but a great read".
9 by 4 by 1.
emt 377 emt 4
I like that.
Also, GP is an imbecile.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
99.9% of all the species ever to exist are extinct. I am pretty sure that every species is "facing extinction."
Current change is within the range of natural variation.
Assuming your assertion is true, it's not going to stay in that range much longer. On our current path parts of the planet will become so hot that they will uninhabitable to humans. That's totally out of wack.
Anons need not reply. Questions end with a question mark.
99.9% of all the species ever to exist are extinct. I am pretty sure that every species is "facing extinction."
Sure... but this is the difference between dying of natural causes and being brutally murdered. But hey, keep up the semantics, asshole. ;)
Anons need not reply. Questions end with a question mark.
When was that? 1750?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
I watched this video on YouTube just a little while ago. I've not really looked into the science of it nor modeled the impacts he's talking about but it might be possible that our earth is a remnant from a not-that-long-ago clash with an itinerant planet's moon. We live on the half of a then larger planet that was smashed by that moon, the rest became an asteroid belt and probably our moon. I think this is a more likely explanation for why a huge part of the crust might be missing than it having been scraped by icebergs. I'm just guessing the icebergs wouldn't have scratched that deeply and it seems like the fossil record would still be there at the bottom of the ocean if it had happened that way. Although I like the tectonic plate subduction argument, clashing rocks in space is much more violent and attractive.
https://youtu.be/ogw6BJRL_rQ?t...
This has to do with Sumerian civilization and the possibility of extra-planetary beings having given us technology way back then. If you're completely closed to that idea, this may not be for you. OTOH, you may be able to compartmentalize and accept the interplanetary collision separate from the extra-terrestrial civilization interference argument.
Only I can judge you.
but it checks out.
Jokes aside, approx 38 % of Americans believe in "Young Earth" creationism and 24% believe everything in the bible is the literal word of God ("literal" here means that nothing is a parable).
Hi! I make Firefox Plug-ins. Check 'em out @ https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/
You must have head of the Roman Optimum and the Medieval Warm Period - and the many other examples of this. Even the Little Ice Age.
1. The Medieval Warm Period was localized to the north Atlantic region, with the pacific region getting colder. Current warming is increasing average temperatures across the globe.
2. The cause of the Medieval Warm Period (as per the link) is believed to have been solved.
3. Atmospheric CO2 has increased from ~300 to ~400 PPM since the 60s, in line with increased fossil fuel emissions.
4. The cause of the current warming is believed (by 90+% of the scientists investigating it) to have been solved. Spoiler alert it's the increasing atmospheric CO2.
Generally not all at the same time though, we tend to call those mass extinctions.
It seems like we're worried about climate change, and willing to spend trillions of dollars (or some politicians are trying to get us to spend that much, that is)
Actually politicians are giving trillions of dollars to the fossil fuel industry in subsidies to help make climate change happen.
Not really, the numbers you're using are pretty much bogus.
From the same Wikipedia article - "The externalities accounted for are broad enough that oil companies not paying for automobile accidents is considered a subsidy."
Aliens had a quarry here for a billion years or so before moving operations elsewhere...
Anyway what would really blow some people's minds and start some speculation would be if in exploring other planets such as mars, we find the same discrepancy during the same time period... Some destructive stellar event perhaps?
Also one of the big detractors of a past advanced civilization is the lack of any evidence surviving at all. However if about a billion years of geological data is missing, that's a pretty big gap to fall into!
Anyway before just now I didn't even know about the "Great Unconformity" which is pretty cool and interesting in of itself!
Even the vox article that picks the highest figure apart agrees the figure is in the trillions.
Jakobshavn Glacier is the world's fastest glacier and moves 66-150 feet per DAY! Glaciers typically only move about 3 feet per day.
https://en.wikipedia.org/wiki/...
Crazy.
But but but ... if you want a flow, you need a downhill. Surely not EVERYPLACE a glacier existed was downhill! Where's the bottom?
Oh ... yeah ... those subducting tectonic plates :-(
You don't need a downhill necessarily. A glass of water poured onto a flat and level surface will still flow and spread out.
=Smidge=
Comment removed based on user account deletion
Comment removed based on user account deletion
Well, no. It never has over geological history, has it.
Yeah, I'm not talking about geological timescales, I'm talking about human timescales. By 2100 it's going to be 7*F hotter globally and that's a conservative estimate. That's a HUGE shift which is unprecedented. After that it's only going to get hotter until we do something about. You would have to be stupid or insane to think this is normal.
Anons need not reply. Questions end with a question mark.
Plus if the earth starts to cool like that we will have centuries to come up with a solution, perhaps burning that fossil fuel we kept in reserve..?
You are not thinking about all this in terms of momentum - way easier to keep the Earth from sinking into a decline, than it is to stop a decline in progress (especially given how long it would take us all to agree the danger is real).
We have lucked out into warming the climate by about the right amount before we switch to mostly alternative energy sources.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
Comment removed based on user account deletion
Good grief. Do you really believe that? It's complete and utter nonsense.
Perhaps you should tell that to the Trump administration because that's what they reported.
Anons need not reply. Questions end with a question mark.
Comment removed based on user account deletion
They've all been captured by this nonsense.
What's more likely, that climate scientists who have studies the Earth for decades are correct or some fool on Slashdot knows better despite never actually studying the climate? Occam's razor does not favor you.
Anons need not reply. Questions end with a question mark.
Comment removed based on user account deletion
Wow, you look at scientists and scientific evidence and decide it's all politics. You have brilliantly deluded yourself, sir.
Anons need not reply. Questions end with a question mark.
Comment removed based on user account deletion
Right. You know, all a researcher has to do is be a "climate skeptic" and they get funded by any number of oil companies, they don't even have to be a climatologist. Have you considered that fact?
Anons need not reply. Questions end with a question mark.
Comment removed based on user account deletion
Let's put it this way: the evidence for warming from CO2 is good. The sensitivity is nothing like the scenarios you suggest. The evidence for all the feedbacks needed to generate "runaway warming" is flimsy to non-existent.
Nobody claimed it was a runaway effect. The estimate is based on past, present and projected pollution. The report has 500 pages explaining this or you could have simply read the article.
There's been a 14% greening of the planet over the last 33 years as a result of the extra CO2 in the atmosphere (from satellite studies). This remarkable fact has been almost invisible to the mainstream media, NGOs and other activist scientists involved in perpetuating the paradigm.
I'm aware that the planet is getting greener as a result of CO2 and climate change. It's understood that flora will flourish in some regions while dying in others. The issue with climate change has always been about the death of fauna and the migration of arable regions of land. It's when the weather becomes erratic that crops are threatened but some flora will thrive. This doesn't mitigate the damage of climate change.
I would suggest you turn down your hysterics knob a few clicks.
You dismiss science as being hysterical instead of pointing to research that counters the evidence put forth? You response is as sound as that of an anti-vaxxer who is certain autism is a just a shot away.
Anons need not reply. Questions end with a question mark.
Comment removed based on user account deletion
Haha, don't be daft. The 7C mentioned earlier is absurd based on the physics. Almost all of that increase is "runaway effect" (positive feedback).
7C? Who's the daft one now? Both I and the article clearly state it's 7F. The only runaway is effect being calculated is our use of polluting fuels in addition to the damage already done (which yet to come to full fruition).
The models using this clearly diverge from actual reality, which is why they have to be "tuned" to past data periodically. It's an exercise in curve fitting. People like you seem to think they're making some kind of super-robust prediction. Nothing could be further from the truth.
You're right that it's perfectly accurate but the "tuning" is not arbitrary, it's identifying previously unknown factors and correcting data from previously unidentified ill-calibrated sensors. For every time it's been "tuned" it's always turned out our previous estimate was too optimistic.
How is an argument to doubt the science because the reality is worse than predicted supposed to convey that in the future reality will be better than predicted?
Anons need not reply. Questions end with a question mark.
Comment removed based on user account deletion
Wrong. It includes things like water vapour increase with temperature increase.
Those are feedback effects but they are far from being runaway effects. Perhaps you define it differently but to me if it's a runaway effect that means it's self-sustaining.
There's no evidence this is net increase or decrease as increased water vapour implies increased cloud cover, which itself reflects sunlight.
Wow, you are arrogant to think you are the only person that has even consider this. Understanding hydrology is the cornerstone of weather prediction.
The tuning is against past data so the model looks like it's accurate. You show the graph without any divergence today because you fitted it to past data, so it looks "accurate". The prediction of future warming is way too hot because the feedback assumptions in the model are wrong
The problem with this idea is that the models have been overly optimistic and it's hotter now than it we previously predicted. Assuming they are just data fitting then it's going to be even worse than predicted.
My argument is that it's not politically correct to research positive changes from warming and CO2 fertilisation. If you want tenure, you won't do it. If you want research grants, you won't do it. If you want other academics to say hello to you on campus you won't do it. And if you don't want to be piled on by mobs of NGO supported tards on social media, you won't do it.
You have presumed people are researching positive or negative impacts but research doesn't assume what the value of the impact beforehand but rather explains what has happened and concludes possible futures. If there are tangible benefits of any kind then Oil companies will fund that research and spend millions advertising it.
Anons need not reply. Questions end with a question mark.