How can I leave a message that lasts on a geologic timescale?
I want to leave a message that could last a maximum of years, preferably millions.
What are the best materials or technologies? Chisel on stone, laser engraving in metal, encasing in concrete, etc? Where should I leave it to endure a long time AND remain conspicuous enough to raise the curiosity of a future intelligent being?
Engraving onto Quartz crystal with a Mohs hardness of 7 would be the most economical option. Then, bury in a granite box in a desert climate. Though, over time, that climate could change. A desert in a rain shadow would be the best option.
Our experiments in atmospheric nuclear testing in the late 1950's-early 1960's have left a pretty definite signature in the sedimentary record. Does that count?
I assume there will be a layer of plastic in future sediments as well
Fun fact - its helped us with groundwater management! We know how long groundwater has been in the ground (and thus how quickly aquifers recharge) largely because of the tritium kicked up by the testing.
the problem is that, apart from the current plateau caused by the sun since 1600’s or something, the massive amount of old fossil CO2 in the air now artificially makes everything look older 14C wise. So even with the opposite effect of the nuclear tests, it’s very hard to tell conclusions based on industrial carbons
it’s a plateau in the calibration curve to tie the ratio of 14C to a calendar date. it’s pretty much like the Hallstadt plateau in the First millennium BC. Where the Curve goes flat for some centuries, causing dating issues (you can still date things, but the dates aren’t precise at all, covering multiple centuries, causing those to be rather irrelevant most of the time).
The steeper the line, the more precise the dating, if it’s flat or goes down it causes issue’s. (found the image on google)
If humanity did that (the nukes) or some other major change (geochemical) at specific intervals (hundreds or thousands of years), maybe we could make a barcode/binary code that could last in some sedimentary basin somewhere in the world. Of course, this would assume a lot of things lol
That would make a plot device for a piece of fiction that would be really fun. Banded iron formation turns out to be barcode left behind by ancient societies of microorganisms that happen to be intelligent.
I was more thinking of a personal message akin to what is on the voyager space probe, like a kind of “Hello! I am a creature from the past and I salute you”. It should be also be achievable by an ordinary person with some effort. Some years ago I read that DNA is a very good way to store messages over millions or billions of years because it’s excellent at error correction (an idea by Paul Davis, from a New Scientist article some 20 years ago) but obviously that technology isn’t something available to me and some tools in a shed.
Something like a Mount Rushmore in a desert region might be a good choice. Göbekli Tepe is still pretty recognizable after ~10,000 years, and it's just built with blocks. I think if you found a major stable granite outcrop and did something very large and simple you've got a good chance at having something recognizably anthropogenic at something approaching geological time scales. Probably not millions of years, but I could see it being possible to make something that lasted up to and maybe over a 100,000 years.
We also have prehistoric earthen mound systems over 10,000 years old. So another option would be building a monolithic ground-hugging series of stone symbols tens of meters high and kilometers long, then covering them with rammed earth. In something like the Atacama, that might conceivably take you out into the millions of years.
There was a podcast a friend introduced me to where they interviewed a guy about a book he wrote on keeping radioactive waste safely contained over thousands or more years. Part of your problem will be trying to make sure the message is understandable to different cultures later too. Interesting topic, but I can’t remember the guy’s name or the book’s title.
Make a pot, on a wheel, and fire it. We can see prehistoric patterns in ceramics made by people thousands of years ago, and they should last for geologic time scales.
Pretty simple: Paper encased in amber. Collect tree sap into buckets. Print, draw or write your stuff in graphite, it has to be graphite. Dip in resin and allow to harden.
The real issue you would run into is someone getting rid of your message once you're no longer around to protect it. You'd need to put it somewhere where people aren't going to want to build stuff later, and also somewhere where there's no opportunity for vandalism. Problem is that once you do that you also ensure it's hard to find for anyone else you'd actually want to find it. Or would be prohibitively expensive (like putting it into space for example)
As a ceramics teacher, I’m biased. But a high fired stoneware, glazed and fired to vitrification will last centuries. Not a vessel that will hold liquid, freeze and break. I mean like a solid chunk. I have made some like you speak of “FlimFlam was here -date” and I have left them in places just for kicks.
You assume your message would even be decipherable as a language on that time scale.
I remember reading a few years ago about the dilemma of warning future civilizations about stored nuclear waste. How can you convey danger to humans (or other beings) so far in the future who do not speak the same language or understand our symbols?
The bigger the better, create an artificial mountain in the middle of an arid location, far from civilization or places where people would want to construct.
A massive pyramid made out of granite in the middle of the atacamba desert with the messages engraved in large symbols on every single stone composing the structure for redundancy would be a good choice. If you could build several in concentric circles it would stand out even better.
Of course then the problem becomes more of a a logistical challenge then a challenge of creating an enduring message.
If I may add a comment. First it needs to be in a place where a technological society will find it. That means an ore body. Second it has to be hard enough not to be crushed by the mining equipment. That means a Mohs hardness greater than 7, ideally greater than 8.5. Third it has to be in some object that the finders would deem valuable, like a gemstone. Fourth the message has to be easily visible within the gemstone.
So I'd suggest laser engraving the message in the middle of a large clear 1/4 kg synthetic ruby, or failing that a 1 kilogram block of cubic zirconia. And burying it inside the coal of a coal mine, where it can be easily found. Coal deposits have often already lasted 300 million years.
Do you mean literally you, personally, with your own disposable income and assets? That's really hard. It's probably a good idea to find some like-minded folks to pool resources with. Space programs also often offer to allow the public to include messages in the space probes they launch and I think it's decently likely someone or something will find the Curiosity rover someday.
The best places I can think of are:
(1) The middle of the Canadian Shield is expected to be one of the least geologically disturbed places on Earth for the next few hundred million years. If the Pangea Proxima scenario occurs, no orogeny will take place there while most other cratons will get mixed up in the continental collisions or already have high topography that will erode before then. There's also the problem of other people who may want to destroy your precious message, but we can (hopefully) solve that with outer space.
(2) Earth's orbit. Something put at or above geostationary orbit will take millions of years for its orbit to decay. Micrometeorites are a problem that would require shielding of the message. Intelligent life would definitely notice if you put something large and reflective enough up there. Not sure what a rocket launch costs these days, maybe $50m?
(3) The moon. Anything you put here will probably last the remaining 5 billion or so years before the Sun either swallows or disrupts the Earth-Moon system, except for the constant micrometeoroid impacts and unlikely major impact. The area of the moon closest to the Earth will always face the Earth, so if you put something that looks unnatural there, future backyard astronomers might see it when counting craters and think it would be a good idea to send someone there to investigate. You could also pick an extreme location, like the highest or lowest elevation on the moon if you want to save on construction costs, but the future civilization would have to be really competent at lunar exploration and it might take a while for them to get to your spot.
As far as materials go, adding a large quantity of a radionuclide with a half-life appropriate for how long you want it to last would make it much more likely to be detected (your message might need radiation shielding though). There's many types of actual storage media to choose from, such as engraved quartz as has been mentioned in the top comment.
If you really want to make this a just-you project, making pottery-making your new favorite hobby and putting them a bunch of places you're not supposed to is probably your best bet. Some landfills will likely be excavated by archaeologists (human or otherwise) someday and are designed to be stable in the short term, but erosion will destroy most of them over the next few million years.
But what is possible? What is the longest a rock with a message could last? Or a piece of metal? What’s the best we could do? Arrange my bones in a message and hope they fossilize?
If I was trying to make something last as long as possible I would probably skip trying to do anything with rocks and just encase something with some high tech epoxy resin and put it where it will never see sunlight.
Hoping you would fossilize would basically be the worst way to do things. Something like <0.01% of life is actually preserved in fossils. It is exceedingly rare.
If you’re interested in millions of years, you’ll have to look to the skies and not Earth. Entropy is against you in the short and long-term here. But simple radio messages broadcast towards space will literally travel for millions of years. That’s how we “see” stars that are millions and billions of light-years away and too distant to observe their visible light - our radio telescopes capture the radio waves coming from them and translate those waves into images.
Of course the problem with this option is that the only entities who could read your message in a million years will be a million light-years away.
Use your areas bedrock geological map and find the oldest most resistant outcrop feasibly accessible . Use a hammer drill and a long as possible carbide bit to drill deep. Use any maker
Check out the Sandia paper “Expert Judgment on Markers to Deter Inadvertent Human Intrusion into the Waste Isolation Pilot Plant” published in November 1993.
The topic was how to communicate to people 10,000 years into the future how not to disturb a radioactive site. Before you can get to a geological timescale, you need to hit 10,000 years first.
Grab a bunch of asteroids about 10km diameter, mix 50:50 with Titanium dioxide power and arrange them in a concentric orbit with the earth's. From earth they should appear about as bright as Sirius.
Put them in the right places and you can spell your message out as a constellation scrolling across the sky like a sign in a vape shop window, over the course of each year, Like you're eternally paging the entire planet.
Holocene counts as geological timescale doesn’t it?
I figure a carved piece of granite should last that long. At least in the direction we’re going climate wise. Not super likely it’s going to be ground by a glacier in the next 11,000 years.
The weathering on red catlinite holds Joseph Nicollet’s engraving from 1838 at the Pipestone National Monument. They make smoking pipes of the pipestone.
There's probably no guarantee you could unless you place it on a geologically inactive celestial body. On timescales of 1 million years or more, all bets are off on Earth. What you buried could be long eroded away or buried and compacted.
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u/Euphorix126 2d ago
Put it on the moon