[thrashh]

That’s possible that they don’t have the same materials as us but they would have the same problems.

Take plastic or metal. Their main draw is that they do not decompose or degrade. There are a billion problems that can be solved when you have a material that does not naturally degrade or decompose.

So even if this civilization did not use plastic or metal, I find it hard to believe they didn’t come across a problem that needed a stable non-self-destructing material, which would then have been left behind for us to discover now.

It’s not feasible to build anything advanced if all your materials naturally decay.

It’s true that there are fewer decomposing organisms the farther back you go, but you have to go way way back to a point where the chance of intelligent life existing is pretty low.

[mrangle]

Absolutely metal and plastic decompose and break down, respectively.

[inglor_cz]

Not all metal. Buried gold retrieved from ancient graves looks very "fresh".

[MichaelZuo]

After ten million years even a large gold ingot would entirely be subsumed by the surrounding matter. Assuming a 10 nanometer/year erosion.

[jiggawatts]

Also most of the noble metals would remain pristine: platinum, iridium, etc…

[userbinator]

The latter, back into oil.

[thrashh]

Sure, but on very long timescales. And eventually once you make enough of it, it gets lodged in all sorts of places, some less susceptible to decomposition, such as humans in bogs or mammoths in glaciers.

I just find it hard to believe there to be not a single trace of anything.