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

http://www.amazon.ca/World-Without-Us-Alan-Weisman/dp/0002008645/ref=pd_bowtega_1?ie=UTF8&s=books&qid=1209058142&sr=1-1

>there was a show on discovery recently about the earth post human. It said something like in 1000 years, all traces of human occupation would be buried, eaten, or non-visible. When mother nature tires of us or we pollute to the point that all is garbage and unusable, we will be swatted like bugs and the earth will renew.