It'll erode away, like any rocks would over such spans. What makes you think it would be more durable than anything in the natural world? Entire mountains and whole oceans can change their shapes in 50 million years so why should a relatively tiny lump of concrete survive longer?
Oh, come on. So you think we have no rocks more than a few million years old?
What? Of course we have rocks that are millions of years old. I'm saying the concrete of the Chernobyl sarcophagus would get eroded away - you have
seen that concrete breaks down over relatively short times, right? - and the remains would be caught up in the rock cycle. The broken concrete would become coarse sediment and get mixed into the soil of the region.
Sedimentary rocks are made out of eroded igneous and metamorphic rocks, and metamorphic rocks are made out of metamorphosed igneous and sedimentary rocks, and igneous rocks are cooled and crystallized magma, which may have had sedimentary and metamorphic rocks in it at some point. There are specimens of all these types that are millions of years old, but particularly for the sedimentary rocks, the rocks are from HUGE
deposits that took a long time to accumulate anyway. The tiny bit of concrete in the sarcophagus isn't going to remain intact for millions of years. It may end up in a sedimentary layer, though. Would that count as "intact" for you?
I fully comprehend deep time. All I am saying is that if a dinosaur's broken eggshell can last 70 million years, then a LOT of what Humans have done will last just as long.
Like what? You have to admit, you've not thought of anything that will remain intact on Earth for millions of years. Metals oxidize and concrete breaks down. You can see these things happen on the timescale of your own life
. What makes you think anything we've built is that durable when we can watch things break down in our own lifetimes?
Consider how many
dinosaur eggs must have existed across the entire Mesozoic era. And then think about how many dinosaur eggs we've actually recovered. All the dinosaur eggs in the entire world's museums are a tiny
fraction of all the dinosaur eggs that ever existed. Some things don't survive because they're really durable, they just survive because they're merely lucky
. Even something as fragile as an egg will sometimes get preserved by pure chance.
So perhaps you can tell me why all these huge structure we have built will all be vanished without a trace in a million years while dinosaur eggshells have lasted much much longer. I suspect that things are tougher than you imagine.
I've already explained that to you. Metals oxidize and concrete breaks down. Everything we've built needs maintenance
. Or do you think all those huge structures we've built are just left to fend for themselves after construction is over? If we left everything alone, the environment would break things down over merely hundreds of years. Asphalt roads may leave a thin but recognizable layer in the rocks, though, if that makes you feel better. Dinosaur eggs just had sheer numbers and pure chance on their side to preserve a tiny fraction of them.
Who knows, maybe some freak conditions will preserve a cell phone intact across millions of years. Would you feel better if that were the case?