Humans managed to erase themselves from existence, taking a large part of Earth's higher mammals (apes, cats, dogs etc) with them. Millions of years later, the biosphere has recovered and biodiversity increased rapidly. Surviving smaller mammals evolved into larger and more intelligent creatures. One of the new species has unique characteristics allowing them to control fire, understand abstractions and communicate them to fellow individuals.

Let's say it's 30 million years after the extinction of humans. What kind of technical civilization will the new species be able to create with previously existing fossil fuels depleted by homo sapiens and all of the easily accessible surface ores extracted? What kind of resources will be available?

After 30 million years, some new oil and gas deposits have already formed. New coal deposits have only just started to form and are minimal.

What is left of the human cities now? Cities contained substantial amounts of metal (rebars, wiring etc). Can we assume new ores have been formed from these metals?

What about leftovers of the old nuclear reactors/missile silos? Any other resources for future Edisons to work with?

  • $\begingroup$ Welcome to Worldbuilding, normiesc! If you have a moment please take the tour and visit the help center to learn more about the site. You may also find Worldbuilding Meta and The Sandbox (both of which require 5 rep to post on) useful. Have fun! $\endgroup$ Jul 4, 2018 at 13:32
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    $\begingroup$ Welcome to WorldBuilding.SE! This is certainly an interesting scenario, but I feel like it might fall into the realm of being too broad - you're asking multiple questions at once. You may need to split this up into multiple questions. $\endgroup$
    – F1Krazy
    Jul 4, 2018 at 13:34
  • $\begingroup$ normiesc - maybe split this question to several more specific ones? The subject is fascinating and has already been discussed in some questions on Worldbuilding, but as it stands this question is likely to close for being too broad. Some questions you can ask that fit Worldbuildings platform better: "Can (or how can) an emerging civilization advance technologically on a resource-depleted planet?", "Can (or where can) an emerging civilization find easily accessible resources on post-human earth?", "Humans are gone - what can I harvest from their cities 30M years later?" (continued) $\endgroup$
    – G0BLiN
    Jul 4, 2018 at 14:24
  • $\begingroup$ (continued) in every such question, focus on one aspect of interest, isolating it from the rest. Give as much details to what you are specifically interested in - general questions tend to yield less useful answers (e.g. how did the humans removed themselves from Earth? Total nuclear war will leave very different resources compared to some virus or transcending to a higher non-material plane of existence... ) - you can also link the questions, so that background details in one can be viewed on the others. Welcome to Worldbuilding :) $\endgroup$
    – G0BLiN
    Jul 4, 2018 at 14:29
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    $\begingroup$ Thanks, created a more specific question: worldbuilding.stackexchange.com/questions/117267/… $\endgroup$
    – normiesc
    Jul 5, 2018 at 9:44

2 Answers 2


I am afraid our technological path can only be replicated on a virgin planet, not on one already depleted by a resource intensive civilization.

The reason why I think so is that the first humans to develop technologies like metal forging didn't venture into digging miles of rock to access the ore, they used what was available on the surface. Then, after knowing what to look for, they started digging.

Since surface mines are more economical than underground ones, it makes sense that the shallow deposits of ores have been already used to their very end. Your new sapiens species might even have easily accessible coal or oil, but without easily accessible copper, tin, iron they won't be able to move away from their equivalent of stone age.

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    $\begingroup$ You forgot about the rich mines of mostly refined goods that are our trash dumps. After a million years, they will BE the easily accessible mineral deposits. $\endgroup$
    – pojo-guy
    Jul 4, 2018 at 13:48
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    $\begingroup$ Also, depending on how the humans "managed to erase themselves from existence", ruined cities themselves may be rich in all sorts of materials, plus the chance that some surviving "artifacts" that can lead to earlier breakthroughs and shortcuts through available materials or examples of engineering $\endgroup$
    – G0BLiN
    Jul 4, 2018 at 14:17
  • $\begingroup$ Garbage dumps are too small and after 30 million years they'd be a thin smear between new sedimentary rock units almost everywhere in the world. Our cities will be similarly buried dust and rust too. $\endgroup$
    – Ash
    Jul 4, 2018 at 14:18
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    $\begingroup$ Hi L. I'm not sure of this. 30M years is a lot of time for vulcanism to redeposit minerals and metals on the surface. I wholly agree that it wouldn't be an identical path, but that's a lot of time. Check this out. Besides, other than via a few nuclear explosions, how much metal has actually been "lost?" The answer should be none(ish), right? Old cities would become new surface-deposit metal mines. I'm just wondering. $\endgroup$
    – JBH
    Jul 4, 2018 at 15:05
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    $\begingroup$ @JBH, 30 million years, at an average growth of 1 cm/year means just 30 km of new crust per fault line. Not that much. $\endgroup$
    – L.Dutch
    Jul 5, 2018 at 3:20

Fossil fuels might be overrated here. WE use them because they are cheap, but plenty of somewhat-more-expensive-alternatives are available for both fuels and materials.

The big technological effects of depleted fossil fuels would be much more expensive air travel for the new civilization (less fuel available), rather fewer common plastic goods (more expensive material), and perhaps quite a bit more tree-farming (fuel substitution).

But, of course, those are attempts at equivalent comparisons. A civilization based upon another species won't be equivalent to us - their psychology and culture will be quite different, and that will make a much bigger difference to their technological development than the presence of rich surface ores or the lack of fossil fuels.


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