OK, the human race dies out at its current level of technology. 10M years later, some other species reaches a similar level of technology and scientific learning. Would their paleontologists be able to show that there had been an equally advanced people in the past? If so, what evidence would survive that span of time?
Easily, I would say, assuming they look enough, and assuming they know how to recognise technology in a general sense.
A cellphone or camera dropped into a lake and buried in the silt is going to be recognisable as a technological artifact pretty much forever (or at least until the resulting sedimentary rocks are destroyed by subduction or something).
Assuming there’s still enough raw material left for them to discover radioactivity and nuclear fission, they should be able to figure out that Yucca Mountain and the other storage sites are NOT the result of natural reactors.
When they get to the Moon, they may find the landers, rovers and landing stages. And the golf ball.
Some shampoo bottles have ridges or indentations down their narrow sides that you can fit your fingers into, making them easier to pick up.
Here is the best picture I could find to illustrate this. (See the middle bottle in particular.)
Any future archaeologist who finds this bottle might conclude that the ancient race that manufactured it had a hand with three pairs of opposable fingers.
Radioactive debris scattered across the planet and preserved in sediments and icesheets will also point to nuclear testing. Geographic changes (agriculture, irrigation, mining, drilling, transport etc) will persist for millennia or more. The layer of microfine plastics and manufactured pollutants we are leaving in sediments and sand will be a giveaway - in fact, some geologists think we have progressed beyond the Holocene into the Anthropocene. Many of these things will point to a technologically advanced society, without major items surviving.
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Cities would leave a definite footprint. There would be no natural process which would concentrate so many different metals and petroleum by-products in one small area.
There are various long term archives and time capsule programs across the world, would any of them have even the faintest hope of surviving 10 million years?
Would larger scale objects in the desert survive, even that many years? If the pyramids have survived, what about all the mega casinos in Las Vegas? Would it be that easy for the desert to erase all traces of them? Even something like a vault full of gold coins might be able to survive if it had some lucky breaks.
after 10 million years, a cellphone? Dubious.
Anyone read this book? On topic:
I doubt if any artifacts at all will survive 10 million years. Surface features such as irrigation, terracing, structures, and so on, certainly not. Mines, maybe.
I think it will be a matter of finding anomalous concentrations of materials, and I think that effect will be subtle. Something on the order of our civilisation’s discovery of the Iridium anomaly in the 20th century.
The pyramids are only a few thousand years old. That’s a lot less than 10M years. Is there a current estimate as to how much time the pyramids have left assuming no regular upkeep?
I don’t know. It is kind of hard to judge when a deliberately aranged pile of rocks will weather enough to look like just a random pile of rocks.
You can start with a semi-random, best guess assumption about the rate of surface erosion in the desert (say, 0.1 mm per year) and work out that the Great Pyramid (139 metres) would be completely levelled after 1.4 million years.
Testing the assumption - if the Pyramid is 4,500 years old, that rate of erosion would have removed 0.45 metres of material from its surface. Is that realistic? Conservative?
How fast would buried non-reactive material such as Teflon or Glass last? I would think that, in the absence of exposure to weathering, an aweful lot of plastics, especially fluorinated ones like PCTFE would be practically indestructible, and are clearly not natural. Buried glass would be similarly unreactive. I see no reason that these could not last millions of years. And we have immense tons of such materials in disposable and disposed products Even if the metals rust away and the cardboard breaks down in the 21st century middens that are our landfill, there will be plenty of bottles , boxes, and widgets made of plastic and glass (along with other obviously artificial non-reacting stuff like carborundum and borazon and artificial diamonds, all used as grinding compounds. Or large concentrations of unlikely compounds as silicon nitride.
Our “cloud-piercing cities of porcelain and adamantine steel” may not last above ground, but, like the Krel, our below-=ground stuff will last a long time. Only it’ll be our garbage, not our self-maintaining power supplies and Everything Machines that last.
(The Krel garbage dumps probably survived long after the Krel died. I’ll bet Dr. Mrobius never studied those. )
In my Aerospace Propulsion class, we talked about the types of alloys used in modern jet engines. Our professor told us that the materials are so hard and so chemically resistant to just about everything that it would take a volcanic even or subduction under the crust into magma to erase them.
What about cities buried in sediment? My WAG is that buildings would certainly not be preserved intact. But even if the asphalt, concrete, and bricks crumble over millions of years, they will leave behind a footprint of definitely non-natural materials. That would perhaps end up as a layer of lime, gravel, clay, and tar, all arrayed in an irregular grid.
Most metals would surely corrode, but wouldn’t a few survive for eons? Historically a few metals have been mined in “nugget” form, which means they survive in big chunks over geologic time. So all of our gold, copper, platinum, and perhaps a few other rare metals would survive as solid lumps, even if most are squished beyond recognition over geologic time. I’d further WAG that ancient buried jewelry stores would be a literal gold mine.
How about glass and ceramics? Those can survive almost completely intact since antiquity. Again, I wouldn’t expect much (if anything) would survive intact over geologic time, but ceramic roofs or all the window glass downtown would be pressed into pretty unusual aggregate materials.
Missed edit:
As an example of what might be possible over the OP’s time frame of 10 million years, consider that paleobiologists have been able to dig up lots of information about human ancestors in that time frame. For example, the early hominid Ardipithicus was discovered in 4.4 million year old sediments. The paleobiologists could also learn about the contemporary ecology, by cataloging fossils of animals, plants, and seeds, as well as examination of soil materials. Thus they conclude that Ardipithicus lived in a forest.
Compared to analyzing tiny fragments of bone, twigs, and seeds in a rocky hill side, I’d think that recognizing cities 10 million years from now would be a piece of cake.
Hostess Twinkies will still be intact, I assume.*
and on a more reasonable note: railroad and highway tunnels would still exist as unnatural, hollow tubes, even after 10 million years. And they should be reasonably easy to discover. The entrances will be covered in rubble, but if somebody dug through a bit and suddenly 'emerged" into a tunnel with smooth walls, it would be hard to find an explanation that didn’t point to human technology.
*(sorry, Mr. moderator man, …but I couldn’t resist. Besides, it’s after the first 10 posts, so please don’t spank me)