Previous civilization

[Gibsons]

Concrete would be sand and pebbles by then.

Buried in mud, in a place that has little geologic activity? I really don't think so.

 

[Nik]

The really large and solid structures might break up some, but they'll still be there. A concrete road might get all cracked up, buried in mud, etc. But 10k years from now, someone could dig up part of it, realize it goes for miles in either direction, all at a pretty constant width, the paint might even survive in parts... seems like that would be hard to miss.

Yep! Concrete wastes away because we drive on it, not because it simply exists. Do you understand how thick roads are? How deep they go down to be able to maintain their shape and support hoards of multi-thousand-pound vehicles across it constantly? Roads, alone, would stand the test of time, considering we still have stone roads that are used to day that have been used for hundreds and hundreds of years. Modern road materials will last sooo much longer.

What about buildings? What about basements? What about hardened compounds for military, government, and financial institutions? I'd suspect those would be in pretty good shape if all they had to deal with is weather and time.

 

[sandorski]

Buried in mud, in a place that has little geologic activity? I really don't think so.

Buried in mud will make no difference. Roots will cause most to be destroyed.

 

[sandorski]

Yep! Concrete wastes away because we drive on it, not because it simply exists. Do you understand how thick roads are? How deep they go down to be able to maintain their shape and support hoards of multi-thousand-pound vehicles across it constantly? Roads, alone, would stand the test of time, considering we still have stone roads that are used to day that have been used for hundreds and hundreds of years. Modern road materials will last sooo much longer.

What about buildings? What about basements? What about hardened compounds for military, government, and financial institutions? I'd suspect those would be in pretty good shape if all they had to deal with is weather and time.

Plants, heat/Cold, Water, they all break down concrete fairly quickly(geologically speaking).

 

[Nik]

Plants, heat/Cold, Water, they all break down concrete fairly quickly(geologically speaking).

Which is why we have archeological digs showing mud, wood, and stone building foundations depicting an entire city, roads, clay pots that are several thousand years old, right?

Because all the stuff made out of steel and titanium and iron and lead and concrete aren't as sturdy as mud, wood, and stone huts?

Right?

 

[jonks]

plot of Fringe

 

[sandorski]

Which is why we have archeological digs showing mud, wood, and stone building foundations depicting an entire city, roads, clay pots that are several thousand years old, right?

Because all the stuff made out of steel and titanium and iron and lead and concrete aren't as sturdy as mud, wood, and stone huts?

Right?

All those things decay. Besides, so bits of pipes are buried, maybe some steel joints lie about here or there, who would find these things, never mind recognize them as something as grand as what they were once part of. Archeologists might recognize the existence of a city/settlement, but have no idea of the true extent of it.

 

[lyssword]

*FRINGE SPOILERS*

Fringe the tv show has this as a part of their main plot

 

[Nik]

Facepalm. Nobody's saying that they expect cities to be bright and clean in 5,000 years. However, I'm under the impression that buildings would still be standing in thousands of years and some of them, certain ones, would be perfectly capable of functioning then, too, but I suspect most of those would be very hardened buildings like underground bunkers, bomb shelters, certain parts of military installations, etc.

 

[sandorski]

Facepalm. Nobody's saying that they expect cities to be bright and clean in 5,000 years. However, I'm under the impression that buildings would still be standing in thousands of years and some of them, certain ones, would be perfectly capable of functioning then, too, but I suspect most of those would be very hardened buildings like underground bunkers, bomb shelters, certain parts of military installations, etc.

those would, some would collapse, but ya they could be intact.

 

[tk149]

The only thing I could think of would be nuclear material. If you find isotopes that don't occur naturally but have to be manufactured in breeding reactors, that would point to previous intelligent life.
We have found fossils from millions of years ago, how much more should synthetic material be preserved in similar manner?

caveat: This is all just speculation in good fun

How long is the half-life of these unnatural isotopes? Long enough to last 10,000,000 years? I have no idea. What are the odds that such material would remain sufficiently concentrated over the course of a few million years (e.g. not spread out by flowing water), and found by the next civilization? I am certainly no expert, but I doubt that there is much of this material around in the first place.

You have a good point with fossils. But keep in mind that while we have found many many fossils, there have been many many more living creatures in the history of the planet. How many fossils would a mere 10,000 years of human civilization produce?

Would an inhuman intelligence even recognize the artifacts? If you had never seen a pair of pliers before, and then saw a "fossil" of one, what would you think it was?

I am also reminded of another SF story. In that book, an archaeological team is working at an ancient dig site and finds a soldier's metal dog tag. The professor in charge assumes its a practical joke, and throws the tag away. What if humans have actually discovered evidence of a previous race, but since it does not fit into our world view, have discarded it?

And then there's always Planet of the Apes, where the successor civilization attempts to destroy any proof that the previous race existed at all.

Anyway, this is what I think about before falling asleep at night.

 

[Kntx]

We dig up dino bones that are 65 million years old. Methinks some there'd be evidence of artificial stuff for at least that long.

 

[JTsyo]

History channel had a show dealing with this very subject. From what I saw on it, for about 100K years, you could still tell a lot about humans from what remained but when you started getting into a million range there wasn't much left. They were looking at a marco level though not what you would find digging somewhere.

 

[Thebobo]

We dig up dino bones that are 65 million years old. Methinks some there'd be evidence of artificial stuff for at least that long.

yea for thta long for sure but say half a billion or more years ago if a meteorite or comet of sufficient size hit us it would of melt the entire earth’s mantle for several miles deep. That would destroy any evidence of any civilization. There are some scientists who believed that has happened to our planet several times in the distant past.

 

[Dr. Zaus]

yea for thta long for sure but say half a billion or more years ago if a meteorite or comet of sufficient size hit us it would of melt the entire earth’s mantle for several miles deep. That would destroy any evidence of any civilization. There are some scientists who believed that has happened to our planet several times in the distant past.

What's a scientists?

 

[dennilfloss]

It's very hard to completely erase traces of an industrial civilisation, particularly for future geologists. Where are their mines? They'd have needed mineral resources just like us and exploited them. That leaves scars that are very hard to erase and in predictable locations; particularly their first mines would be in the same easy-to-exploit spots as ours. We'd had at least found those spots already depleted. The deep mine shafts would still be present and recognizable even if filled with debris.

Think about it, fossilization is a very unlikely even, yet we do find fossils. An industrial/advanced civilization produces all kinds of hard debris and waste. Think dams, vaults, anything hardened. You basically need to melt or completely rework the planet's upper crust to erase our own imprint on it.

 

[Kntx]

yea for thta long for sure but say half a billion or more years ago if a meteorite or comet of sufficient size hit us it would of melt the entire earth’s mantle for several miles deep. That would destroy any evidence of any civilization. There are some scientists who believed that has happened to our planet several times in the distant past.

I think if the entire earth melted there might not be any signs of prior civs. Point conceeded. An analogy, is an ice cube. If I leave an ice cube on the counter it will melt. 6 hours later, perhaps someone would think there was just a water spill. There would be no way of knowing there was once an ice cube there. Days later it will evaporate and dry. Then who could know?

 

[Gibsons]

Plants, heat/Cold, Water, they all break down concrete fairly quickly(geologically speaking).

Pompeii was buried for 2,000 years, multiply what little decay it's had times 10 and it's still easily recognizable as a city.

 

[sandorski]

Pompeii was buried for 2,000 years, multiply what little decay it's had times 10 and it's still easily recognizable as a city.

It was practically instantly sealed.

 

[Gibsons]

It was practically instantly sealed.

Over 2k years, almost no heat/cold damage, water damage, tree root damage, none of the things you were saying would destroy buried concrete.

Maybe it takes some concrete or stone structure, or entire town, 100 or 300 years to get buried. It's likely going to stay mostly intact from that point for thousands of years. And there are lots and lots and lots of towns, roads, statues, aqueducts, sewers, cemeteries, etc around now. If it's not volcanic ash, it could be a mudslide, or a sand dune or who knows what.

 

[a123456]

History channel had a show dealing with this very subject. From what I saw on it, for about 100K years, you could still tell a lot about humans from what remained but when you started getting into a million range there wasn't much left. They were looking at a marco level though not what you would find digging somewhere.

I thought exactly of this but couldn't pinpoint the name when I saw this thread.

There's also a picture describing the more exact theory on when things will go away here:

http://images.thetimes.co.uk/TGD/picture/0,,351113,00.jpg

Basically, stuff like concrete can last about a thousand years in the open but it may last a bit longer if it's buried. With plate tectonics going on, a big chunk of it might not appear to the finders.

Plastics are one of the more hardy substances, estimated to last 50k+ years. But nuclear waste is 2M+ years easy. I think the half life of some of the isotopes is in the billion range but those might be naturally occurring.

The show made a point that stuff on the moon, like the lunar landers, etc. would actually last way longer (millions+ of years) than any stuff on earth since there's basically nothing going on on the moon compared to the earth.

 

[Nik]

What's a scientists?

and with what evidence?

 

[Nik]

I think if the entire earth melted there might not be any signs of prior civs. Point conceeded. An analogy, is an ice cube. If I leave an ice cube on the counter it will melt. 6 hours later, perhaps someone would think there was just a water spill. There would be no way of knowing there was once an ice cube there. Days later it will evaporate and dry. Then who could know?

The minerals and other components that are not H^2O that have not evaporated would have been deposited on the counter's surface as evidence of what was once there. Additionally, depending on the state of the material left over, we may be able to tell whether it was frozen or not. :thumbsup:

 

[IGBT]

I hear there's remnant remains of license plates on mars. NASA knows this.