[safety1st]

After 100 million years, would any of those signatures be detectable? Glass decomposes, only takes a million years or so. The continents themselves have rearranged so any bets about structures that still remain are off. Depletion of easily available resources perhaps, but if a bunch of iron deposits were mined out that long ago, how would we know now?

This is the topic of the paper, I think the authors settled on climate markers and radiation from elements like plutonium-239 as among the very few pieces of evidence that might still be around on that time scale. They also observe that there has likely been enough exploitable energy in the form of oil, natural gas etc. to support an industrial civilization since about 250 million years ago.

[ethbr0]

Some glass decomposes.

It's chemically inert like aluminum (after oxidizing, e.g. foil), so the processes acting on it are mechanical and subject to probability.

Some amount is going to be abraded, buried, etc, but you only need a few pieces to remain. Given their ubiquity in our culture, there'd be some somewhere.

[carlmr]

>Given their ubiquity in our culture, there'd be some somewhere.

Yet we can barely imagine a society without wheels, but some human cultures in South America didn't get that idea.

Assuming that every civilization invented glass is very tenuous.