To get metamorphism it needs to be deeply buried and squeezed in an orogenic province.

Your hypothetical outcrop will have to have buried by transgressive ocean sediments (sea level rise) then exposed again by regression. So a coastal location at a delta would work, or a coastal swampy area along a passive margin that is not going to experience much tectonic modification.

There are speculative maps of the continental positions 100 my in the future on the net. The positions are less speculative than the sea levels, in my opinion.

So yeah, go ahead with the ceramics. Glass is a different story, it may suffer “de-vitrification” in the long run.

Is THAT assumption where the flaw in my argument is? That after 100 million years it is unreasonable to expect any current day strata to not undergo metamorphosis? I think the fact that we are able to find fossils from 100 million years ago seems to show that assumption is not unreasonable.

All that is required is that the artifacts be buried and not eroded or undergo metamorphic processes. Bones need much more special conditions in order to be preserved millions of years

Some contact metamorphic rocks might be similar in crystallography and chemistry, especially shales intruded by basaltic magma. Hornfels is a really hard and dense c-metamorphic rock. The general term of similar rocks, “skarn”, was supposedly a word derived from a curse made by Scandinavian miners.

Chert lasts for a very long time. Some of the oldest rocks on earth are cherts. They are similar to ceramics, sort of.

So, yes, I think those spark plugs, insulators, and grandma’s fine china plates will last a long time.

However, unlike those thick banded iron formations of the earliest deposits, the thick skarns, there is simply not enough ceramics in the world to make anything more than odd fragments in a schmear of odd sediments on an enormous bagel.

We know about dinosaurs because they existed for a very long time. Humans not so much. There is a vast record of dinos in the geologic column long before the K-T event. Our creation of ceramics (I include pottery here) goes back what, a few tens of thousands?

I would be interesting to take a representative sample of the average landfill and subject it to the temperatures, pressures, and aqueous chemistry that is diagenesis and lithification of sedimentary rocks. Why not kick it up to various metamorphic facies, while we are at it? A landfill’s components brought to high grade metamorphic P/T conditions?

There are ways of doing this experimentally right now. But the samples are typically small. And we cannot recreate millions of years in a lab.

If we want to use ceramic clasts in a humanite in a Science Fiction story, we need to trace the entire geologic history of that deposit.

Our strata and the strata below it will contain HUGE numbers of extremely linear deposits of copper, from pipes and wires buried by us- all terminating in areas where the strata have been disturbed in unnatural ways (former buildings) filled with unnatural deposits (the remains of those buildings)

It really seems to me this would leave traces for many hundreds of millions of years.

We have no idea just how intelligent, or sentient, the dinosaurs were. And their avian descendants can be quite intelligent, even having something like culture, in a way. The flock of magpies that steal our cat food certainly have a vocabulary.

A sentient species may use selective breeding or even advanced bio-molecular techniques to provide it with artificial life forms to use as tools, food, sensors, transport, weapons, construction materials and power sources. Actually, humans have been doing that (rather crudely) for thousands of years! Maybe other species are much, much better at it.

Or what about cetacean-like creatures so intelligent and capable in their environment they have never bothered with technology. They still could have mathematics, language, poetry, politics, history, philosophy, art…? Their science might be as complex and advanced as ours, just not based on building gadgets. After all, do whales need flint tools, or fire, or pottery, or glass, or woven fabric? And why should they take up agriculture when dumb food, both plant and meat, is so plentiful and easy to harvest? All they really need to do is learn the habits of the species they depend on, and where they are located, and to communicate that knowledge to their fellows and pass it on to their offspring. Even beasts can accomplish that with instinct, with real intelligence it might make domesticated plants and animals, or machines, unnecessary. We haven’t evolved the mobility or the strength to do that, we had to cheat—with technology. Its conceivable any highly complex ecosystem, like a rain forest or coral reef, or even a slime mold, might be “intelligent”, and we just can’t even recognize it because we operate on a totally different time scale and business model..

On my road to Damascus, I have started to come to some conclusions regarding my interest in SETI. Maybe the Fermi Paradox is in place because ET has never developed spacecraft or radio telescopes. On most worlds with sentient species, the inhabitants have learned enough about their environment to exploit it in ways other than technology, say by learning enough about it to adapt to it, even when it changes. Perhaps that happened in the past, but it left no archaeology. Maybe its happening today, we just can’t recognize other life forms as sentient who haven’t adopted the same techniques we have.

Think about intelligent termites, distributed intelligence in a hive where the individuals are essentially mindless automata, but the community itself is capable of sentience? All they would leave behind is the nest architecture, structures with no permanence whatsoever unless constantly maintained. And the knowledge necessary to construct and maintain those structures is exercised by the entire hive, not the individuals that make it up.

Maybe intelligence is not so rare in the universe. Maybe tool-making is the Great Anomaly. Yes, we are a race of engineers, maybe the only one. It doesn’t mean everyone else is. It doesn’t even mean anyone else is.

https://www.cbc.ca/radio/quirks/june-30-2018-a-comet-from-the-stars-microbiome-and-arthritis-polar-bear-treadmill-and-more-1.4724524/fossils-of-our-civilization-what-humans-will-leave-behind-1.4724531

https://www.science.org/content/article/what-fossils-will-modern-day-civilization-leave-behind

https://www.washingtonpost.com/national/health-science/could-intelligent-life-have-existed-on-earth-millions-of-years-before-humans/2018/04/20/9b13e7ac-433a-11e8-8569-26fda6b404c7_story.html

The only major fossil site from the KT event that I am aware of is https://en.wikipedia.org/wiki/Tanis_(fossil_site)

I have kicked around similar ideas of a small colony buried by volcanic ash from the Eocene, like Pompeii.

It all comes down to how it gets preserved.

I like to flesh out sci-fi story ideas in my head (almost none have found there way onto paper) and when I was younger I played around with the idea of a sentient species becoming technologically advanced ~66million years ago on earth… but could find no plausible way to believably explain why their traces had not been discovered by humans…

From your statements you seem to think the evidence might be easy to miss after tens of millions of years?

This is one of the arguments about how to define the start of the Anthropocene. The presence of radioactive nucleotides is a good candidate, in my opinion.