How do we know the age of the Earth?

Discussion in 'Earth Science' started by Saint, Apr 22, 2017.

  1. origin Trump is the best argument against a democracy. Valued Senior Member

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    LOL, that cracked me up...
     
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  3. timojin Valued Senior Member

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    My belief is not my stumbling block . What I see and you to but you might deny it. Science is not static we have continuously new information from the field ( exploration ) . As you pointed in wikipedia your site. Much of the result of the 4.5billion is based on the reference of the meteorite in the canyon El diablo. That reference is based that the meteorite, is assumed that the earth and the meteorite come from the same place from the same nebula, and the meteorite is a fragment that did not coalesced during earth formation. What about if the meteorite is an late comer long after the earth was formed ?
    I grant you the decay Uranium tho Lead is very good, but that adds an other question . As to who is older our sun or the earth , that we can think also that we might not be a product of the same supernova.
    I agree much with products formed in the lab , because we are in the same time scale , but when it come to cosmology on their time scale , I am not sure things are 100 % certain
     
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  5. exchemist Valued Senior Member

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    Well no, the main evidence is not the meteorite but the lead/uranium ratios in rocks from the Earth itself. That is why I focused on that in my previous response.

    The meteorite merely serves to suggest that the solar system itself seems to have an age similar to that of the Earth - thereby reinforcing the theory that it all condensed from the same primordial dust and gas cloud as part of a single process.

    Of course it is just evidence and not proof, just like anything else in science, but it is a solid and fairly well corroborated hypothesis. And so far as I know there is no contrary evidence to make us suspect there may be something wrong with it. So "fantasy" it is not.
     
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  7. karenmansker HSIRI Registered Senior Member

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    Timojin: Most cosmologists would likely agree somewhat. The overall (average) composition of the earth is comparable to the (major, minor, and trace elements/isotopic) composition of a typical carbonaceous chondrite meteorite. This influences some to conclude that the earth and 'meteorites' have similar common origins - compositionally, at least - and ages, albeit earth continually re-cycles itself to form younger lithologic components. Also, from historical investigations of available meteorites, scientists see a full range of compositional meteorite types that are representative of most of the earth's litho-structural configuration - e.g., not discreet intervals, but on average: nickel -iron ~ core; stoney-iron ~ lower mantle; chondrite ~ upper mantle. [BTW, the 'crust' of the earth represents recycling of mostly deeper layer source material that interacts with shallow, surficial, and atmospheric processes - a sort of slag, or crust - one might say.] One might then entertain the likelihood that meteorites (en toto) might represent fragments of one or more such disagregated early planetesimals (now mostly residing in the asteroid belt) that were once more discrete (and magmatically segregated) bodies in our solar system. On occasion, we witness fragments of these planetisimals (meteorites) as they impact the earth. (all IMO, of course!)
     

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