Go to Michael Crichton's website and read some of the lectures he has given to Congress on the matter.....

>I would suggest an excellent lecture: World Without Us by Alan Weisman.
>
>anything made of bronze might survive in recognizable form for millions of years—along with one billion pounds of degraded but almost indestructible plastics manufactured since the mid-20th century
>

That's a LONG time to speculate about.