Wouldn't you find human artifacts all over the place even 60 million years from now? We have fossils much older than that, so wouldn't many many objects like gold wedding rings be around 60 million years from now?
Plus, it’s possible that some hypothetical dino civilization mastered bio-degradable materials early on before taking to the stars ;-)
Invasion of the Space Dinos!
http://tardis.wikia.com/wiki/Dinosaurs_on_a_Spaceship_(TV_st...
Wasn't the article more meaning "the oldest part of the earths crust, that's still on the surface"?
eg everything else has been buried, or destroyed, via other geological processes
“For example, the oldest large-scale stretch of ancient surface lies in the Negev Desert. It’s “just” 1.8 million years old—older surfaces are mostly visible in cross section via something like a cliff face or rock cuts. Go back much farther than the Quaternary and everything has been turned over and crushed to dust.”
The article is in no way stating the oldest bit of the Earth's crust is 1.8 million years old. Crust has a specific meaning, the chemically differentiated rocks at the surface i.e. everything but the very very rare bits of exposed mantle. Oldest oceanic crust is <200 Ma, oldest continental crust dates to the Hadean (4.4 Ga, if you set the bar at only zircons).
Bones are common, fossils are formed by a relatively rare geologic process. Fossilization supplants slow to rot organic material with stone, embedding it in the strata, in just the right conditions. It's unclear to me what (if any) industrial rememants would become fossilized and if they'd be recognizable as such.
Going past a few tens of thousands of years, fossils start to either be of very large things, or of very large communities of small things.
I'd be surprised if any future scientists could find even a single piece of modern jewelry a million years from now.
Granted the coral fossil in the living room is many small animals, but it’s not a big object.
But typically those are extracted from deposits with lots of similar pieces, like the three-foot-long slab of fossilized seabed I had. Professionals might carefully carve something like that up and turn it into lots of small fossils of fish, but they all came from the same chunk of rock.
That's what I meant by "large communities of small things".
So, it's possible that some bunker of physical storage of wealth, with gold bars for instance, will survive a hundred thousand years longer than most of the rest of our civilization. Or, maybe one of our many many landfill deposits will end up with just the right conditions to preserve for a long time the preservable stuff. But I don't think bits of gold jewelry will just be sifted out of the dirt.
Come to think of it, the best bet for evidence of our civilization a million years from now are currently the bits we've left behind on the moon, and Musk's roadster! (The latest calculations have a 6% chance of it crashing back to Earth within the next 3.5 million years -- but it will continue to swing back around every hundred years or so until then.)
Take Mesoamerican gold for instance: only about a thousand years have passed since much of it was made by humans, but it's still considered a rare and valuable archaeological find. (Granted, it was produced in smaller quantities than today.)
Gold is melted by fires; gets scattered and buried by a million years of bioaccumulation; seas move, rivers appear or disappear, continents drift a little, climate changes, glaciers come and go and further destroy evidence.
Google is feeding me a lot of really dumb stuff at the moment when trying to come up with numbers, but I'd guesstimate that most traces of our civilization would be buried a hundred feet below the surface after a million years' time. That makes it pretty difficult to find small things.
There is some hope though! It's thought that the melting process was done in Spain so as to allow a reliable royal assay, if so then some of the ships that sank in the trade may have holds full of crushed and squashed precious artefacts.
I can find one not-great reference suggesting that carbon fiber items are expected to be in landfills for on the order of hundreds of years -- not very long in geological scales. Steel rusts and degrades spectacularly easy, and a lot of the steel we've produced is exposed to conditions helping it along.
Neither of these items is susceptible to the process of fossilization; it's that process that helps preserve some things for a long time. The stuff we make has to last that long all by itself, and we're not that good at making things yet.
We also see things trapped in glaciers, but if the timescale is large enough for all the glaciers to have melted...
(I was going to raise the same point, thinking of low-background steel and the effects of nuclear testing on our atmosphere, but after some more reading it appears that most of those isotopes decay over shorter periods or weren't sufficiently elevated to be discernible from the background, if it were being examined in the far future.)