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It would be really weird if a Silurian civilization randomly pumped out a bunch of radioactive iron and didn't do anything else. Any industrial civilization co

by jjk166 2y ago

It would be really weird if a Silurian civilization randomly pumped out a bunch of radioactive iron and didn't do anything else. Any industrial civilization comparable to ours within the past few hundred million years would be very detectable today - reinforced concrete, plastics, ceramic shards, mined fertilizers, all would show up in the geologic record. Further one would expect fossil evidence of some lineage approaching intelligent levels over time. The only plausible place for a Silurian civilization to hide would be several billion years ago, so long ago that the crust they lived on has been subducted back into the mantle, taking the evidence for their existence along with it.

jamiek88 2y ago
I agree with this comment fully but I just wanted add a little on the subduction. It’s a lot quicker than people think. The vast majority of rocks we can find that aren’t of extra terrestrial origin are only around 200 million years old. >A few seams of very old rock have been discovered, such as the billions of years old Nuvvuagittuq greenstone belt in Hudson Bay, Canada, as well as similarly ancient outcrops in Australia, China, Greenland and South Africa. But even this very old rock has had a complex history. “Exposure to high temperatures during past collision can change the chemistry,” notes Boyet. “This disturbs the isotopic system we use for dating rock.” https://cordis.europa.eu/article/id/442712-are-all-rocks-on-earth-the-same-age https://cordis.europa.eu/article/id/442712-are-all-rocks-on-...
- jjk166 2y ago
  Most continental crust is over 2.5 billion years old. Very old rocks aren't exposed at the surface very frequently, because they tend to get covered over in younger rock, but it's still there, and we can sample it with deep drilling. Oceanic crust tends to be less than 200 million years old, though even then there are some much older examples.
adolph 2y ago
> It would be really weird if a Silurian civilization randomly pumped out a bunch of radioactive iron and didn't do anything else. We never know any data before interpreting it through theories. All observations are, as Popper put it, theory-laden, and hence fallible, as all our theories are. Deutsch, David. The Beginning of Infinity Probably the best evidence that Fe60 is not "Silurian" in origin is that it still arrives on Earth [0]. 0. https://webarchiv.typo3.tum.de/PH/gams/fileadmin/w00bjs/www/Master_Thesis_Dominik_Koll.pdf https://webarchiv.typo3.tum.de/PH/gams/fileadmin/w00bjs/www/... Addendum: The Silurian Theory is sometimes an interesting way to explore ideas. I don't think that a large pre-human "civilization" need take the same form as what we think of as human civilization. Even some large human civilizations like that of the Indus River Valley or Harappan culture are less understood because they left less in the way of stuff analogous to current times: "In sharp contrast to this civilisation's contemporaries, Mesopotamia and ancient Egypt, no large monumental structures were built. There is no conclusive evidence of palaces or temples." https://en.wikipedia.org/wiki/Indus_Valley_Civilisation https://en.wikipedia.org/wiki/Indus_Valley_Civilisation

by jjk166 2y ago

jamiek88 2y ago

I agree with this comment fully but I just wanted add a little on the subduction. It’s a lot quicker than people think. The vast majority of rocks we can find that aren’t of extra terrestrial origin are only around 200 million years old. >A few seams of very old rock have been discovered, such as the billions of years old Nuvvuagittuq greenstone belt in Hudson Bay, Canada, as well as similarly ancient outcrops in Australia, China, Greenland and South Africa. But even this very old rock has had a complex history. “Exposure to high temperatures during past collision can change the chemistry,” notes Boyet. “This disturbs the isotopic system we use for dating rock.” https://cordis.europa.eu/article/id/442712-are-all-rocks-on-earth-the-same-age https://cordis.europa.eu/article/id/442712-are-all-rocks-on-...

jjk166 2y ago
Most continental crust is over 2.5 billion years old. Very old rocks aren't exposed at the surface very frequently, because they tend to get covered over in younger rock, but it's still there, and we can sample it with deep drilling. Oceanic crust tends to be less than 200 million years old, though even then there are some much older examples.

adolph 2y ago

> It would be really weird if a Silurian civilization randomly pumped out a bunch of radioactive iron and didn't do anything else. We never know any data before interpreting it through theories. All observations are, as Popper put it, theory-laden, and hence fallible, as all our theories are. Deutsch, David. The Beginning of Infinity Probably the best evidence that Fe60 is not "Silurian" in origin is that it still arrives on Earth [0]. 0. https://webarchiv.typo3.tum.de/PH/gams/fileadmin/w00bjs/www/Master_Thesis_Dominik_Koll.pdf https://webarchiv.typo3.tum.de/PH/gams/fileadmin/w00bjs/www/... Addendum: The Silurian Theory is sometimes an interesting way to explore ideas. I don't think that a large pre-human "civilization" need take the same form as what we think of as human civilization. Even some large human civilizations like that of the Indus River Valley or Harappan culture are less understood because they left less in the way of stuff analogous to current times: "In sharp contrast to this civilisation's contemporaries, Mesopotamia and ancient Egypt, no large monumental structures were built. There is no conclusive evidence of palaces or temples." https://en.wikipedia.org/wiki/Indus_Valley_Civilisation https://en.wikipedia.org/wiki/Indus_Valley_Civilisation