If whole populations were wiped out and the world was repopulated by a small remnant would that not account for it? Or if an extinct human species had an advanced civilisation?

Yes. We'd find mines, where the richest veins were mined out and what's left is spread in a pattern that clearly appears to be "a rich deposit but with the best stuff taken already". The mine itself would have long collapsed but would also leave interesting evidence, a pattern of mismatched geological layers that rather than looking like an earthquake or a tectonic upheaval would be something that is relatively clearly shaft-shaped and if followed into the mountain would open out into a pattern that indicates intelligent mining activity as the anomaly is further charted.

Places where there is suddenly a vast collection of foreign rocks from the other side of the world that can't be explained by glaciers.

Radioactivity from nuclear tests that can't be explained by stellar phenomena and leave a layer of weird isotopes and isotope ratios all around the world, as we already have done.

And while we aren't to the point we'd have found this quite yet necessarily, evidence on the Moon where unlike Earth evidence probably would in fact persist for millions of years, especially if it ever attained any scale, e.g., "a large complex of cities" might still leave a visible mark on the surface easily visible to modern satellites and clearly with no other explanation available as to what caused it.

People get stuck on the idea that the only way to determine there was intelligent life earlier is to find a super complicated artifact which obviously can't survive, but there are footprints we've left in the world that are way, way larger than a cell phone or even a major city.

I don't find it hard to believe we've lost entire human civilizations. In fact I'd call it the smart bet. Maybe those civilizations were even a bit more sophisticated than we'd have thought, with maybe an earlier and entirely unknown Iron Age popping up somewhere for some period of time or something. But this is the first major technological civilization this planet has ever seen, even across geological time scales. And those lost human civilizations never reached to the level where they took all the easy resources like we have, because if they had, we wouldn't be able to get them. Some resources we call "non-renewable" do replenish on a few million year time scale, but we also pull lots of resources out of billion-year-old rocks, such as copper mines in northern Michigan which are pulling resources out of pre-Cambrian rocks. Clearly nobody else has been there, at scale.

> Any idea?

Not really, because none of this passes the smell test if you know even a tiny bit about geology and paleontology. The most solid arguments are religious texts, there is not really any substance other than that.

I mean sure, if they somehow didn't have any trade goods that went in land, didn't work with metals enough to do any appreciable mining, and didn't breed any plants or animals enough to change their genetics. Any hypothetical hidden past civilization would have to have been weird in a number of ways to not leave any evidence.

>coastal civilizations say, a million years ago, would be now under the crust.

Nah, you way off on that, coastlines have remained relatively same last million years, def not subducted into an ocean trench

Huh?

We have plenty of fossil evidence from, from your example, a million year old hominids. Far more than we would need to expect to see evidence of civilization.

Subduction makes up for a tiny tiny proportion of where coastal land "goes" in any age.

You'd need an enormous set of coincidences for a past civilization of hominids to go unnoticed.

That is explicitly referenced in the article.

I think there is no evidence for it, but I think the point of the Silurain hypothesis (which the article does not convey well) is that if there were such civilisations we would not know as its unlikely we would find any evidence.

> I think the article greatly underestimates our archaeological capabilities.

"they found a single forerunner to their idea of deep time. It came not from science, but from science fiction. At this level of conjecture, there’s little difference. It was an episode of Dr. Who" also betrays an ignorance of the trope originator.[0]

[0] https://en.wikipedia.org/wiki/Serpent_Men

depends how you define civilization level life.if you mean we cant be bumped back to hunter gatherers without wiping out almost all of us, you are probably correct. If you mean we will always have computers and the ability to split the atom, i dont agree. Knowledge and industry is way more fragile and we have loat working knowledge of simpler processes in favor of more advanced ones so it wont be that easy rebuilding through the lower rungs of the tech tree.

No. The idea is they could have lived and thrived for a few thousand years a few million years ago, then gone extinct.

We’ve already got fossils of dolphins. Not exactly the species we know today but close enough. We have enough fossils to trace their evolution since their ancestors walked on land. So yes, we definitely would have evidence that dolphins were here.

We’ll never know of the existence of most species that ever existed. Fossilization is rare.

The claim isn't about the age of rock, but that the surface has churned almost everywhere. Israel does contain the oldest measured continuous surface at about 1.8M yo, but nobody claims to have looked everywhere.

The counter argument: dinosaurs were around for a staggering amount of time, no pun intended. 165 million years is reasonably long enough to ensure they left behind some nests, bones, and a feather or two. Modern humans have been around for more like 0.02 million years.

The counter-counter argument is that while we’ve been here for a comparative blink of an eye, we’ve left behind 4 orders of magnitude more stuff than just nests, bones, and a feather or two.

Actually correct. We have very very few fossils compared to the millions of species that have evolved and gone extinct over 4 billion years.

The fossils we do have are of highly successful species in that geography. It’s a matter of chance, leaving behind a fossil, after all.

And unlike biological matter that can fossilize, industrial structures etc do not. All our manufactured stuff has very short life once it reaches the crust and starts getting compacted.

The more time you add, the better the odds we’d find this evidence lost.

And if this wasn’t a global, but more localized pre-human civilization, the evidence would be thinner still.

Which is why this isn’t a scientific hypothesis really. It’s more showing you the limits of scientific inquiry into the deep history of Earth.

> And someone is saying there could have been an entire advanced civilization 400 million years ago, large and powerful enough to cause climate change, and that no traces of it would possibly be left?

If humanity vanished today, in 1 million years almost all of our artifacts would be gone or burned under miles of subduction.

In 10 million years there would literally be nothing left.

How can a galaxy spanning civilisation fail. If life can spread to other worlds, unless you get FTL, how could you end all life in a galaxy

As such it seems impossible for life to have reached interstellar travel anywhere in the Milky Way before at most a few million years ago, otherwise we would see it.

Which is weird because life surely can’t be that rare in the entirety of space time.

Of course the galaxy could be teaming with non interstellar life, but once you reach mankind’s level of sentience and technology it dormant seem a massive jump to interstellar, and once that happens there’s no way to put the genie back in the bottle.

> time is as vast as space.

This is what I always say to "Why haven't we found any aliens yet??"

Hell, we wouldn't even have known about the existence dinosaurs, lifeforms on THIS VERY PLANET, if we hadn't chanced upon their remains.

> Petroleum could be the byproduct of a previous civilization.

How so? We know how it forms, there is no real gap in understanding there. What could lead to the kind of distribution of oil and gas fields we can observe?