[embedded_hiker]

There would be thousands of perfectly circular holes drilled straight through many older layers of rock, with casings, from fossil fuel extraction. They would presumably be filled with sediment, but still obviously artificial.

[ClumsyPilot]

You are assuming that very small and spesific objecta would be found undergroud, intact

The next civilisation doesnt get like a perfect 3d scan of the entire planet, kilometers deep. They get sporadic evidence that they happen to find

[hh3k0]

Those would surely all be crushed beyond recognition by tectonic shifts?

[scythe]

In areas undergoing tectonic shifts, sure. In some regions, the same rocks have existed for a long time:

https://en.wikipedia.org/wiki/Oldest_dated_rocks

[nemo]

We have fossils from the Cambrian period ~500 million years ago that include many traces of holes from burrowing animals. We've identified animals from ~500 million leaving many different kinds of traces as well as from fossils. 500 million years from now humans will have left many remaining traces. While older fossils are rare and precious, there's no generalized entropy that just destroys all old things (until there's a supernova/mega-meteor/etc., eventually the planet will be gone with enough time). In the right conditions much can be preserved for hundreds of millions of years. Many human artifacts like gold and other inert metal tools will be around besides the many physical changes we've made across the surface of the Earth.