See also the Silurian Hypothesis [0], which I think just got a lot more interesting as a thought experiment.
[0]: https://www.theatlantic.com/science/archive/2018/04/are-we-e...
Betteridge's Law confirmed. We can track down fossils billions of year back by observing the way they shaped the encasing rocks, and not once have we noticed a ceramic shard, a metal bit or the silhouette of a plastic object.
> There are fossils, of course. But the fraction of life that gets fossilized is always minuscule and varies a lot depending on time and habitat. It would be easy, therefore, to miss an industrial civilization that lasted only 100,000 years—which would be 500 times longer than our industrial civilization has made it so far.
Sandstones. Sandstones originate as far as hundreds of million years in the past. Occasionally they harbor fossils, which are indeed rare. But a lot of sandstone is made of sanded up organic material which we can readily identify, even if we can't point to the specific organism they originated from. We only need a tiny industrial-related grain of sand (ceramic, glass, metal, plastic traces) to point to a past civilization. Nobody ever noticed such a grain of sand.
> So it might take both dedicated and novel detection methods to find evidence of a truly short-lived event in ancient sediments. In other words, if you’re not explicitly looking for it, you might not see it. That recognition was, perhaps, the most concrete conclusion of our study.
I'm not bullish on pre-historic civilization, and neither is the article, but the takeaway is we may not have reason to expect that we'd have found these tiny industrialized traces without a search aimed specifically at them. As far as I know, such searches have not been carried out in earnest to date.
So not a truly short-lived event in ancient sediments then.