If human civilization ended tomorrow, how long would it take for all evidence of our existence to disappear?

The longest lived structures would be large stone megaprojects like the Pyramids, the Great Wall of China and Mount Rushmore. These would outlast any other kind of composite structure no matter how robust, with the possible exceptions of nuclear waste sarcophaguses and some specialized bunkers, like the Svalbard Global Seed Vault. These could last easily centuries without maintenance and still be recognizable, but not more than a few thousand years. Common made things like teapots, cellphones, cars, bridges and skyscrapers would all be equivalent to trash in their longevity, due to being made of thin, refined parts and limited design lifespans.

The longest lived human-made structure would likely be the leftovers from the Apollo missions on the moon. These could remain in a recognizable state for about 50 000 years, because the Moon is so geologically inert. There’s a chance it could be accelerated by a random asteroid or two, but it’s a slim chance.

Much archaeological evidence would continue to suggest our existence for many thousands of years, under a few meters or few dozen meters of dirt: building foundations, glass, landfills and collapsed tunnels could be around until they broke down into the crust and did something interesting like fossilize (or whatever  CRT TVs and daipers do when left buried for ten thousand years). This kind of evidence, if it could be found by a future civilization, would still be around until our continents shifted about so much that the landmasses we know and love were gone completely and sunk into the Earth’s interior. That could take many millions of years.

All satelites and space missions would either get covered in dirt or be perturbed and crash within a century, with the notable exceptions of the Voyager probes, New Horizons, and possibly a blastplate from Operation Plumbob.

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