The Times (UK) offers a timeline of how long it would take human traces to dissipate, if we disappeared.
Some of the milestones:
- 20 years: rural roads and villages are overgrown by vegetation
- 50-100 years: urban areas are overgrown
- 100 years: wooden buildings decay
- within 200 years: metal and glass buildings collapse
- 1,000 years: “most brick, stone and concrete buildings are gone;” atmospheric carbon dioxide is back to pre-industrial age levels
- 50,000 years: “most glass and plastics degrade”
Some movies about the distant future don’t quite reflect how temporary most human artifacts are:
- Even after 1,000 years, the rusting hulks of cars are still sitting in the streets in Battlefield Earth.
- The metal Statue of Liberty is still recognizable far in the future in Planet of the Apes.
- Old books are still partially intact 800,000 years in the future in The Time Machine.