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by ElFitz 1063 days ago
I recall someone asking on World Building StackExchange what aliens could find in a few tens of millions of years or so if the human race were to disappear today [0].

The answer was "not much", aside from discrepancies in metals distribution, with intriguing concentrations of iron oxyde, nuclear waste, or gold.

I am aware it certainly isn’t the most scientific or authoritative of sources, but they made interesting points.

[0]: https://worldbuilding.stackexchange.com/questions/117267/hum...

2 comments

> What aliens could find in a few tens of millions of years

Much more than we are finding. The earth would be a mess with plenty of really puzzling events.

Wild tomatoes with narcissus and flounder genes for example.

Sudden extinction of entire groups of animals and plants in only a few thousands of years

Radioactivity holes and missile holes fossilized with metals in the bottom

Cities, and cemeteries in particular, would be a geological nightmare waiting for an explanation. A collection of grey granite from Canada carved in lames of uniform thick, polished for no reason and accumulated in a point. At 20 meters away another set of lames of Chinese black granite and 30 meters away a lot of yellow marble only known from Italy. All wrapped in asphalt, gravel, glass and concrete. Dumpsters would also be very strange places with plenty of plastics and chemicals that shouldn't be there.

Gems also. Diamonds carved in impossible shapes all ending in a more or less conical tail in the whole planet. Lots of things shaped like a heart. Strange collections of elements with unique properties of the periodic table found always together: Mixed minerals found near, gold, silver and platinum, at tens thousands of Km far away from its known mines. As they are often saved in fireproof boxes, would had survived miraculously in burnt areas.

Implants. Titanium fossils shaped like the femur of an animal (and always the same animal) and porcelain teeth would be enough to show a civilization and signal us in charge of it.

As of last Tuesday, the mark of human indistrial and technology activity on Earth is officially marked in the geological layer:

Welcome to the Anthropocene, Earth's new chapter (phys.org)

https://phys.org/news/2023-07-anthropocene-earth-chapter.htm...

    Since 2009, a cloistered band of hard-rock geologists and other scientists have toiled on a mission of great consequence.

    On Tuesday they will deliver the last of their findings—the location of ground-zero for the Anthropocene, the proposed geological epoch borne of humanity's outsized impact on the planet.
How the weight of the world fell on one geologist's shoulders

https://phys.org/news/2023-07-weight-world-fell-geologist-sh...

    Zalasiewicz pointed to an "embarrassment of riches" of evidence locked in ice cores, sediment and coral skeletons: microplastics, forever chemicals, traces of invasive species, greenhouse gases, and the fallout from nuclear bombs.
Proof humans reshaped the world? Chickens

https://phys.org/news/2023-07-proof-humans-reshaped-world-ch...

    When aliens or our distant progeny sift through layers of sediment 500,000 years from now to decode the Earth's past, they will find unusual evidence of the abrupt change that upended life half-a-million years earlier: chicken bones.
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The announcement described in the first link (unfortunately in german): https://web.archive.org/web/20230714101242/https://www.mpg.d...