5 ms·

Yes, over geologic time, nearly anything has no chance of survival. And, yes, the lifetime of such a civilization may be a window that is, geologically, basical

Yes, over geologic time, nearly anything has no chance of survival. And, yes, the lifetime of such a civilization may be a window that is, geologically, basically invisible. But an industrial civilization makes a LOT of stuff, and much of that is quite durable and easily recognizable as artificial, and is likely to be scattered all over the planet. Given that there are places that preserve tracks over 300 million years old, and fossils, well, up to 4 billion years old, I have a hard time imagining that a worldwide civilization that's producing and using aluminum and titanium and ceramics and all sorts of other stuff on a wide basis would not leave something recognizable in basically all the available fossilizing environments. We might not ever find fossils of the species, but are we really not going to find anything from the million refuse dumps and cities and industrial facilities and whatnot, or millions of miles of roads, or the multi-billions of accidental losses bound to be all over the world? Not to mention objects in high orbit or on the lunar surface, which is a whole other thing. You have to posit a really limited civilization before I believe it.

JoeAltmaier 6y ago
It wouldn't take a complex material to recognize a previous civilization. Their civil engineering activities would give them away completely. Archaeologists can read worked surfaces with amazing skill. E.g. a bed of pebbles could be a lake bed, a road surface, a floor inside a building, a foundation, and there's ways to distinguish them. Unless the soil was erased/reformed completely there would be a record of almost any activity, from digging a post hole or trench, to building a wall then removing it again then dumping construction waste into the hole then plowing it under. All are different from 'native' soils deposited by random processes. Geologic time is not enough to erase evidence of worked soils. Not unless it gets scrubbed to the bedrock and redeposited. And even if that happened some places, it wouldn't happen every place. And its fair to say today, that our civilization has been pretty much every place.
- sjy 6y ago
  Geologic time is certainly enough to erase evidence of worked soils. It spans billions of years, the destruction and formation of continents, and multiple global mass extinctions. Archaeology concerns only the last few million years of hominid activity.
  - mongol 6y ago
    How will asphalt and concrete appear in the geological record? Would it not be identifiable? If we can recognize fossilized bones, a future civilization should civilisation able to recognize concrete with steel rebar inside, no?
    - Balgair 6y ago
      Abandoned asphalt roads quickly return to nature. I remember some disused highways near me that were flaking and crumbling away after only 30 years. So bad that you'd have to walk your bike on them. As for rebar, if any water were to get in there repeatedly it would all just rust away. The specifics of the environment play huge here. Anything in a freeze-thaw cycle would get obliterated. Dry and cool areas would do better, but then only for so long. Maybe if things were intentionally buried in anoxic environments, like many fossils, you'd have a chance at retrieval.
      - JoeAltmaier 6y ago
        Returning to nature is relative. The presence of long-chain petrochemicals in layers where they don't belong, would last for millions of years. And is evidence of that asphalt road.
        Balgair 6y ago
        Yeah, but you'd only see that in sedimenting areas there were uplifted and then weathered; like orogenized river deltas. After that, you'd need to have a lot of samples in the sediment so that there'd be enough exposed rock to care to look at all. Then you'd need enough sample in the rock to detect above background noise. Then you'd need to conclusively explain away any natural causes for the presence of the asphalt, which is naturally occurring anyway. I'm not saying it's impossible, but it would take a lot of luck.
        mongol 6y ago
        Yes but considering the total length of paved roads in the world, often using asphalt, how they stretch terrain from coast to coast, on all inhabited continents, that some of it will pass areas that will be uplifted and brought to daylight - I see it as inevitable. It might need a trained eye to see, but it would be there.
sjy 6y ago
The paper addresses this objection in section 1.3: “That this paper’s title question is worth posing is a function of the incompleteness of the geological record … The oldest extant large-scale surface is in the Negev Desert and is ~1.8 Ma old. However, pre-Quaternary land-evidence is far sparser, existing mainly in exposed sections, drilling and mining operations. In the ocean sediments, due to the recycling of ocean crust, there only exists sediment evidence for periods that post-date the Jurassic (~170 Ma).”
- ardit33 6y ago
  that is disingenuous... and is just word playing with definitions. Most mountains in Europe have surfaced with the last 10-20 mill years, and they have turned earth around to the point that you routinetly find marine fossis in top of 2000m mountains. If any civilization was around, it would have left a mark somewhere, and mountains would be a great place to spot them. BTW: According to most scientists, the oldest mountain range on Earth is called the Barberton Greenstone Belt and is found in South Africa. It's estimated that the range is at least 3.2 billion (yes, billion!) years old.
  - sjy 6y ago
    I was also surprised by the statement that the oldest extant large-scale surface is ~1.8 Ma old. There is a citation provided for this [1]. It seems the point is that older features like mountain ranges are subject to significant erosion (as you point out, a marine environment can become alpine during the life of a mountain range) and that this could destroy or disperse most evidence of an industrial civilisation that lives for only a few centuries. The oldest surface which preserves archaeological evidence, due to its low rate of erosion, is merely in the millions of years, whereas what we know about earlier periods is extrapolated from a tiny sample of exposed sections of the earth’s crust. Meanwhile, the seabed is recycled on the 100 Ma scale, and eukaryotic life has been around for 2 Ga. That is a lot of recycling. [1] http://geomorphology.sese.asu.edu/Papers/Matmon%20et%20al.%20-%202009%20-%20Desert%20pavement--coated%20surfaces%20in%20extreme%20desert%20(1).pdf http://geomorphology.sese.asu.edu/Papers/Matmon%20et%20al.%2...
candiodari 6y ago
Yeah but I bet there's, even now, like 80-90% (guess) of the planet that don't have a single manmade object on them. And those million/billion years tracts of land that archaeologists see are like 0.0000001% (guess) of the total. Odds seem good that surviving rocks came from very boring, very pointless places.

JoeAltmaier 6y ago

It wouldn't take a complex material to recognize a previous civilization. Their civil engineering activities would give them away completely. Archaeologists can read worked surfaces with amazing skill. E.g. a bed of pebbles could be a lake bed, a road surface, a floor inside a building, a foundation, and there's ways to distinguish them. Unless the soil was erased/reformed completely there would be a record of almost any activity, from digging a post hole or trench, to building a wall then removing it again then dumping construction waste into the hole then plowing it under. All are different from 'native' soils deposited by random processes. Geologic time is not enough to erase evidence of worked soils. Not unless it gets scrubbed to the bedrock and redeposited. And even if that happened some places, it wouldn't happen every place. And its fair to say today, that our civilization has been pretty much every place.

sjy 6y ago
Geologic time is certainly enough to erase evidence of worked soils. It spans billions of years, the destruction and formation of continents, and multiple global mass extinctions. Archaeology concerns only the last few million years of hominid activity.
- mongol 6y ago
  How will asphalt and concrete appear in the geological record? Would it not be identifiable? If we can recognize fossilized bones, a future civilization should civilisation able to recognize concrete with steel rebar inside, no?
  - Balgair 6y ago
    Abandoned asphalt roads quickly return to nature. I remember some disused highways near me that were flaking and crumbling away after only 30 years. So bad that you'd have to walk your bike on them. As for rebar, if any water were to get in there repeatedly it would all just rust away. The specifics of the environment play huge here. Anything in a freeze-thaw cycle would get obliterated. Dry and cool areas would do better, but then only for so long. Maybe if things were intentionally buried in anoxic environments, like many fossils, you'd have a chance at retrieval.
    - JoeAltmaier 6y ago
      Returning to nature is relative. The presence of long-chain petrochemicals in layers where they don't belong, would last for millions of years. And is evidence of that asphalt road.
      - Balgair 6y ago
        Yeah, but you'd only see that in sedimenting areas there were uplifted and then weathered; like orogenized river deltas. After that, you'd need to have a lot of samples in the sediment so that there'd be enough exposed rock to care to look at all. Then you'd need enough sample in the rock to detect above background noise. Then you'd need to conclusively explain away any natural causes for the presence of the asphalt, which is naturally occurring anyway. I'm not saying it's impossible, but it would take a lot of luck.
        mongol 6y ago
        Yes but considering the total length of paved roads in the world, often using asphalt, how they stretch terrain from coast to coast, on all inhabited continents, that some of it will pass areas that will be uplifted and brought to daylight - I see it as inevitable. It might need a trained eye to see, but it would be there.

sjy 6y ago

The paper addresses this objection in section 1.3: “That this paper’s title question is worth posing is a function of the incompleteness of the geological record … The oldest extant large-scale surface is in the Negev Desert and is ~1.8 Ma old. However, pre-Quaternary land-evidence is far sparser, existing mainly in exposed sections, drilling and mining operations. In the ocean sediments, due to the recycling of ocean crust, there only exists sediment evidence for periods that post-date the Jurassic (~170 Ma).”

ardit33 6y ago
that is disingenuous... and is just word playing with definitions. Most mountains in Europe have surfaced with the last 10-20 mill years, and they have turned earth around to the point that you routinetly find marine fossis in top of 2000m mountains. If any civilization was around, it would have left a mark somewhere, and mountains would be a great place to spot them. BTW: According to most scientists, the oldest mountain range on Earth is called the Barberton Greenstone Belt and is found in South Africa. It's estimated that the range is at least 3.2 billion (yes, billion!) years old.
- sjy 6y ago
  I was also surprised by the statement that the oldest extant large-scale surface is ~1.8 Ma old. There is a citation provided for this [1]. It seems the point is that older features like mountain ranges are subject to significant erosion (as you point out, a marine environment can become alpine during the life of a mountain range) and that this could destroy or disperse most evidence of an industrial civilisation that lives for only a few centuries. The oldest surface which preserves archaeological evidence, due to its low rate of erosion, is merely in the millions of years, whereas what we know about earlier periods is extrapolated from a tiny sample of exposed sections of the earth’s crust. Meanwhile, the seabed is recycled on the 100 Ma scale, and eukaryotic life has been around for 2 Ga. That is a lot of recycling. [1] http://geomorphology.sese.asu.edu/Papers/Matmon%20et%20al.%20-%202009%20-%20Desert%20pavement--coated%20surfaces%20in%20extreme%20desert%20(1).pdf http://geomorphology.sese.asu.edu/Papers/Matmon%20et%20al.%2...

candiodari 6y ago

Yeah but I bet there's, even now, like 80-90% (guess) of the planet that don't have a single manmade object on them. And those million/billion years tracts of land that archaeologists see are like 0.0000001% (guess) of the total. Odds seem good that surviving rocks came from very boring, very pointless places.