Comment by kergonath

If they’re a bit observant they will see that a humongous number of animals of the same species shows up suddenly, and localised in big numbers. Besides, there are a lot of signs of human activities. We changed the atmosphere in ways that are likely to show up in sediments. We mined all the minerals we could find to turn them into widgets that are not going to disappear. Our plastic items will end up in sediments all over the place, with wrong isotopic signatures. We find them in all places where we can look, down to the bottom of the Mariana Trench. They are carried to the seas by the same rivers that leave the silt that turns into rocks. Beyond that, we are leaving entire strata of plastics and metals in landfills. A lot of the satellites we put up there will fall back to Earth, but not all of them will. Some have orbits that won’t decay in millions years. There is not a single aspect of the planet that we haven’t touched.