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World's Oldest Rocks Found
Posted by
timothy
on Sun Sep 28, 2008 10:50 PM
from the and-jagger-wants-'em-back dept.
from the and-jagger-wants-'em-back dept.
Smivs writes "The BBC reports that Earth's most ancient rocks, with an age of 4.28 billion years, have been found on the shore of Hudson Bay, Canada. Writing in Science journal, a team reports finding that a sample of Nuvvuagittuq greenstone is 250 million years older than any rocks known. It may even hold evidence of activity by ancient life forms. If so, it would be the earliest evidence of life on Earth — but co-author Don Francis cautioned that this had not been established. 'The rocks contain a very special chemical signature — one that can only be found in rocks which are very, very old,' he said."
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Look at the picture closely... (Score:3, Funny)
Re:Look at the picture closely... (Score:4, Funny)
"And you can see McCain's shadow stacking the layers..."
Proof the world is only 10,000 years old!
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Worlds oldest found rocks found! (Score:5, Insightful)
Isn't it inaccurate to say "World's oldest rocks found" ? I'm a fan of Schroedinger and all that, but just because their the oldest we've observed doesn't mean they are the oldest.
Re:Worlds oldest found rocks found! (Score:5, Insightful)
The 'oldest' (or largest, smallest etc...) is always based on known measurable things. It isn't the the oldest person is the absolute oldest person in the world, just the oldest known. There could have been one person who lived long before we recorded it who lived longer than anyone today, albiet unlikely. It is likely there are older rocks, in fact it is almost inevitable there are older ones, especially if they find traces of life in them. These are just the oldest verified and recorded that we know of.
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Re: (Score:3, Funny)
in fact it is almost inevitable there are older ones
And it is almost certain that we will find at least one of these older rocks. And it is almost inevitable that there will be older rocks than that. Therefore it is almost certain that the age of the earth is infinite!
Re: (Score:3, Informative)
Why do you think we don't know how heavy metals formed??
http://en.wikipedia.org/wiki/Supernova#Source_of_heavy_elements [wikipedia.org]
Re:Worlds oldest found rocks found! (Score:5, Insightful)
Radiometric methods give the date of a *rock*, not the date of the formation of its constituent atoms (which you can't measure because of the "memoryless" property of exponential decay). The idea is that if samarium desintegrates on its way from space to the Earth, it stops being samarium. So by definition, all the samarium found in a rock is "fresh" when the rock is formed. When it desintegrates its products (such as neodymium-142) are trapped in the rock.
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Re:Worlds oldest found rocks found! (Score:5, Funny)
I dated a rock once. Yeah, it was a hard relationship. Most of the time she was just stoned though.
Hey, bad puns. Don't take them for granite.
Yeah, I'll be here all night. (I really should learn to drink less or post as AC.)
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Re:Worlds oldest found rocks found! (Score:4, Funny)
you could have broken the ice with her...
maybe she just likes laying around in the garden...
carbon dating your gf to find out her real age is not going to improve your relationship...
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Re:Worlds oldest found rocks found! (Score:4, Funny)
Yeah, it just makes you look like a moraine.
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Re: (Score:3, Informative)
Educate yourself: http://en.wikipedia.org/wiki/Samarium-neodymium_dating [wikipedia.org]
Re: (Score:3, Interesting)
Ok, so the method is based on a stable decay.
But when/how was neodymium formed? These tests assume the formation was when the earth formed. The earth wasn't born with the birth of the elements that made it up. We should find materials *older* than the earth.
If this test is to be conclusive of the age of the earth, than the formation of heavy elements must occur geologically. What is the geological process?
Re:Worlds oldest found rocks found! (Score:4, Informative)
My understanding of the dating process of zircons (dunno how related this is; too late to RTFA) is that it isn't based on the material itself, but it's position within a crystal. Essentially, there is the (decent) assumption that when a crystal is formed the structure is (mostly) ideal. However, when radioactive decay occurs the element changes, but its position in the lattice does not. Ergo, decay products will be at warped points in the lattice, while identical elements (which would have been themselves at formation) will not. That allows one to count the relative quantity of decay vs. parent and, from the half life, deduce the age.
Again, that's zircon crystals, which are usually the things dated this old, but I'm not sure that's what it is in this case.
What really screws up this business is the fact that we seem to have observed several ways in which the fine structure constant is not, in fact, constant. (Well, that or something else that affects half-life.) Just recently (as posted here on ./) scientists have observed a change that seemed to be related to the distance from the sun. Further, we have known for a while now about natural fission reactors in Africa that, while showing evidence of functioning at one time, could not have possibly ever worked given our current value of the FSC.
In short: looks like radioactive decay isn't so constant.
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Re:Worlds oldest found rocks found! (Score:4, Informative)
Further, we have known for a while now about natural fission reactors in Africa that, while showing evidence of functioning at one time, could not have possibly ever worked given our current value of the FSC. In short: looks like radioactive decay isn't so constant.
Actually, quite the opposite [wikipedia.org]. The Oklo find indicates that alpha has not changed, though it could be that other properties have also changed and exactly offset the change in alpha. It couldn't have happened today because there is to small a proportion of U-235 realtive to U-238, because the former have a shorter halflife.
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Re:Worlds oldest found rocks found! (Score:4, Informative)
There is a process called fission track dating [wikipedia.org] that actually counts the number of paths of alpha particles through the crystal structure (think helium nuclei being shot out into the crystal and leaving destruction in their wake), which represents the number of decays. But this is rarely done in zircon, it is more typical in minerals like apatite, sphene, and micas.
The dating process for zircon used most commonly on this type of rock is called TIMS (thermal ionization mass spectrometry), and this involves crushing a portion of the rock, separating zircon crystals, dissolving them in acid, separating out the U and Pb through a column chemistry process, and then using a TIMS to ionize the U and Pb, and measure the ratio between the different isotopes. Which actually yields 4 different dates for the zicron grain, which can be used to cross check one another.
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Re:Worlds oldest found rocks found! (Score:5, Informative)
It doesn't matter when the elements formed, we just have to know what their relative abundances were then and compare that to the current state.
The neodymium system is complicated, as are all real world measurements to some extent, so consider an idealized system. Suppose that uranium consisted of a single isotope with a half life of four billion years, and it decays to lead. Now further assume that zircons when they form contain some uranium but no lead at all, because its atoms cannot fit into the crystal lattice. If we measure the uranium and lead in a zircon and find that uranium and lead levels are equal then it must have formed four billion years ago, since that is the half life and half the uranium has decayed.
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Re:Worlds oldest found rocks found! (Score:5, Informative)
The reason that old rocks are so important is as follows:
The earth, along with all the planets and sun in our solar system was formed from a disc of dust (same as any other sort of planetary system as anyone can tell). Our earth was initially formed WITHOUT a moon. About 4.something billion years ago, our planet hard some initial surface and crust and all that. About that time, an object around the size of Mars hit the earth. This had a number of causes:
1) It penetrated the surface of the planet (Duh!!) and caused a large amount of the core of our forming planet to get whacked out into orbit.
2) This made the moon if you needed clarification.
3) The force of the blast meant that the effective entire crust of the earth was again submerged into the insides of the earth.
The last part is the most important to this article, as there are very very few "rocks" that can survive that sort of hear/pressure without being changed beyond recognition. One of these is Zircon. So far, some of the oldest rocks to date have been dug up in Western Australia and are Zircon. The belief is that these were either formed on earth prior to the impact or came on the thing that hit us (I can't remember which).
Either way, there you have a small lesson, and also likely the longest post I have written on
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Re:Worlds oldest found rocks found! (Score:5, Informative)
You're close.
"1) It penetrated the surface of the planet (Duh!!) and caused a large amount of the core of our forming planet to get whacked out into orbit."
It's kind of the other way around. The core of the impacting body was mostly incorporated into the Earth (making it, on average, denser), and the Moon formed mostly out of the mantle/outer part of the impacting body and parts of the Earth that were blown into orbit, making it, on average, lighter, and the lunar material has a more refractory composition (i.e. more depleted of volitile material).
"3) The force of the blast meant that the effective entire crust of the earth was again submerged into the insides of the earth."
Hmmmm.... well, most of the entire surface became molten, but I wouldn't describe the process as "suberged", more like "melted", although the dense stuff delivered by the impactor sank into the core.
"The last part is the most important to this article, as there are very very few "rocks" that can survive that sort of hear/pressure without being changed beyond recognition. One of these is Zircon."
Zircon [wikipedia.org] isn't a rock, it's a mineral found in rocks, usually at a percent or less by volume, and it is harder than most minerals to "reset" it by heating. The rock in question is described as an amphibolite [wikipedia.org] (a rock rich in minerals of the amphibole group, although they describe it as a "faux amphibolite", so it's an odd one). Zircon is relevant to the story because it contains uranium, and it is therefore a useful mineral for the U/Pb radiometric dating technique.
The really exciting part is that these rocks also have quartz and magnetite (Fe3O4) layers implying they were originally layered, sedimentary rocks (they've subsequently been heated and compressed to form a metamorphic rock, but the sedimentary signatures are apparently still there). Previously there were only individual mineral grains known that old (also zircons), with the rest of the rock heated and deformed subsequently so that little of the original structure remained.
"The belief is that these were either formed on earth prior to the impact or came on the thing that hit us (I can't remember which)."
They formed on Earth after the Moon-forming impact. That's thought to have occurred within the first 100 million years or so of Earth history, and there are no intact mineral grains on Earth that old (so far), and none are really expected because so much was melted by the event. For older stuff you have to look at meteorites.
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Re: (Score:3, Funny)
Chemical signature ehh?.. (Score:3, Funny)
So, it smells like earth.
But in England... (Score:5, Funny)
...I hear there are some rolling stones that are even older.
Re:But in England... (Score:5, Funny)
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Exciting future prospects (Score:5, Funny)
When asked for comment on what they intended to do with the rocks now that they had them, the lead researcher responded:
"Oh well, you know. Put them on a shelf. Maybe look at them from time to time. We might, when people come around to visit, take them down and let people not touch them! It's all terribly exciting... in fact, I think I need a lie-down."
Chemical signature? (Score:5, Funny)
There is hype in the article (Score:3, Interesting)
2. The evidence for life was speculative at best.
As the earth is known to have had liquid water for some time before the 4.28 possible date, this is not startling news. But they are rocks, and there is the possibility of establishing a case that they needed bacteria to create their striations. That's where the interest lies. It seems a bit too soon for life to evolve by too haphazard a route in that time.
Which implies a catalytic life-shaping environment, or an extra-terrestrial source, or of course, intelligent design. I've no objection to the latter, provided it is taught in a scientific manner. I've also no objection to proposing pigs can fly provided the analysis is, if not scientific, then nicely based on engineering.
Re:There is hype in the article (Score:5, Insightful)
No. Intelligent Design cannot be taught in a scientific manner, unless it is to say "There was no Intelligent Design."
The whole "teach the controversy" is an attempt to trick people into teaching ID, and is a means of validating it.
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Re: (Score:3, Informative)
Re: (Score:3, Informative)
Obviously, there's so much evidence behind evolution, so much correlation between other sciences; but we cannot actually demonstrate evolution in a lab environment.
Sure we can. [newscientist.com]
Well, that depends (Score:5, Interesting)
On how they "teach the controversy".
The way it was handled in my high school science class was simple: a discussion of what "science" meant. Science, after all, is more of a method of discovery by certain rules than a true monolith (such as "science says"). This was then distinguished from spiritual approaches by focusing on physical evidence, falsifiability, etc.
Essentially, the teacher better defined science and distinguished it from religion. She then stated that, as we were in science class, we would learn the scientific take. We were free to believe as we wished - as is the fundamental right of every man, enshrined in the First Amendment and various case law interpreting it - but, regardless of what we believed, we would learn the scientific take in a science class - it only meant sense.
That, to me, is the appropriate way to handle the situation. I particularly liked the way it reminded us more of the scientific method and of the epistemological differences between the hard sciences and other subjects. This planet and its people would benefit a great deal by learning the ability to approach matters in different ways and to even learn to hold two, conflicting ideas in their heads for a moment's time, if not but for the purpose of comparison. We need to trust people to think about things for themselves. Teaching epistemological approaches and focusing on process rather than product is vital to this.
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Re: (Score:3, Interesting)
although, certain atheists would say, there is sufficient evidence that God is a cruel hoax perpetrated by mankind in order to make itself feel better. There's even an evolutionary argument for religion (promotes social cohesion).
Re: (Score:3, Insightful)
Err, depends what you mean by ID, the current ID push seems to based almost entirely on creatiionism and driven by Christian Fundies that are trying to use it as a way to get creationism into schools and the public consciousness in general.
If there was another ID years ago, that's fine, but what most people seem to mean by ID these days is creationism with the word "god" removed.
Rocks and __ (Score:3, Funny)
Discovery of world's oldest rocks challenged (link (Score:5, Informative)
Not everyone agrees.
This was covered a few days ago on New Scientist...
http://environment.newscientist.com/article/dn14818-discovery-of-worlds-oldest-rocks-challenged-.html [newscientist.com]
Re:Discovery of world's oldest rocks challenged (l (Score:5, Informative)
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Perfect opportunity... (Score:3, Funny)
Ah, bible explained after all. (Score:5, Insightful)
Looks like ancient shamans used a DWORD in the Good book to represent the age of the earth. When it was downloaded, the figure of 4.3 billion years overflowed and wrapped around to around 6000 years.
Problem solved.
It's funny though, because, you know, as much as everyone deservedly knocks the 6000 year old figure, few actually probe the ancient conceit that drove it - that is, the universe could not exist without mankind, and so, it more or less exists to serve mankind, and therefor we can spread out across the world and conquer it.
Now, with all of our fancy science of course, we know much better. We know that the universe is billions of years old, and that, we've not actually found a shred of life within it that is not from our planet. Not a peep out of SETI, a hello from another world - not even a cell on Mars- nothing. So, it really looks like, that, we can spread across the world and conquer it.
So, the upshot is that ancient man and today's scientists drew exactly the same conclusion. If we can see it, we can take it. All of this mumbo jumbo about the age of the thing doesn't matter a bit. In the mind of the Pope and Goddard alike, its -ours-.
Re: (Score:3, Insightful)
As a matter of fact, the 4000 BC date isn't a bad estimate for that. It's about the time of the first civilisations - when people stopped living as hunter-gatherers following the herds a
Rocks that are billions of years old? Can't be. (Score:4, Funny)
'Cuz Sarah Palin told me the Earth is only 6,000 years old.
"Ancient Life Forms?" (Score:3, Interesting)
It may even hold evidence of activity by ancient life forms.
Thrintun [wikipedia.org]? Tnuctipun [wikipedia.org]?
Moosenee was the Garden Of Eden? (Score:3, Funny)
Anyone that's been there would find that very hard to believe.
I'm as old as the universe (Score:3, Funny)
I'm as old as the universe (since all my subatomic particles are the same age) but I can only reliably remember back only a week or two.
massive meteor bombardment 3.9 billion years? (Score:3, Interesting)
Re: (Score:3, Informative)
Well, I'm a Catholic (although not a practicing one) and it was never, ever taught in Church or any Church extra-curricular activities that the earth is only 5,000 years old. This is something that is only believed by the crazy Evangelical Christians that belong to "fringe" churches; not the larger more accepting churches. Unfortunately, their numbers are growing.. and fast. It's frightening.
I agree that the good thing about this country is that you can believe anything you want - but the Evangelicals
Re: (Score:3, Interesting)
Ppppphhhttt. I'm a religion-respecting Christian, and I have no problem believing the rocks are 4.28 billion years old, for the following reasons:
1. God could have created them at that age. For example, if I take my filesystem and slap it onto a CD, preserving the original timestamps... what's the true age (or timestamp) of the files on the CD?
2. If I'm going to try to explain something complex to someone who's incapable of understanding it, I generally break it down into chunks they can understand. So if G
Re:4 Billion years old? I don't think so. (Score:4, Insightful)
"If your Bible says that people were made from mud, then either: that Bible story is utterly and completely mistaken; or it is deliberately lying to you."
Spoken like someone who wishes this to be true and in his arrogance claims it must be true.
Why do you have a problem with someone having faith in a religion if they don't let it screw up how they view the world?
Behold! You have someone who believes in God AND thinks evolution is a right clever idea! But rather be grateful that not everyone is insane, instead of seeing hope for the future, you have to attack the person.
You sir, are a moron.
If you are *ever* going to begin convincing people that science has nothing to do with religion (which it doesn't) then STOP attacking them on theological grounds.
Embrace this guy's beliefs the next time some archo-conservative nut tells you the universe is 6000 years old and the world was made in 3 days and that there is no point planning for the future because the world is going to end anyways.
"Any story that tries to tell it otherwise is simply incorrect. Wrong. Utterly mistaken. There is nothing else to it."
You've never heard of allegory then have you? Take a literature class and learn something. There is a reason civilizations have myths and legends they tell stories about, and its NOT because we like to be entertained (though it helps).
Some atheists need to stop treating everything as a personal attack. The egotism sets my teeth on edge.
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Re:4 Billion years old? I don't think so. (Score:5, Insightful)
No, it's only the fundamentalist Christians who would think that, in the rest of the world you can be a Christian without believing every single word in the Bible is the absolute truth.
BTW, I'm not a Christian, I'm just saying you shouldn't judge a faith or set of beliefs by the crazy extremists, otherwise you end up with the "because most suicide bombers are Muslims, most Muslims are suicide bombers" type of argument.
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Clergy letter. (Score:3, Interesting)
Re:4 Billion years old? I don't think so. (Score:5, Informative)
I don't know about "50 years", or how deeply this counts as documentation, but there's a decent run-down here: http://en.wikipedia.org/wiki/Allegorical_interpretations_of_Genesis#Contemporary_Christian_considerations [wikipedia.org]
The "money quotes" are from Pope John Paul II -
The full discourse from the pontiff is linked on Wikipedia, but it's here for your convenience: http://www.ewtn.com/library/PAPALDOC/JP2COSM.HTM [ewtn.com]
HTH.
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Re:4 Billion years old? I don't think so. (Score:5, Informative)
Actually, upon reading the full discourse, the following is an even-more-money-quote: (emphasis mine)
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Re:I'm not so sure about that age thing (Score:4, Informative)
>I recall from some study claiming, that identifying age cannot
>be accurately estimated by carbon-dating beyond 40000 years or so.
Fortunately the rock was not made up of carbon and hence carbon-dating was not needed. The rock did contain neodymium and samarium though which could be used for dating it.
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