If it was biological in nature, then we wouldn't know. That's a thought that can keep me up at night. Imagine an entire civilization based on wood?
But imagine if civilization had ended 500 years ago, or even a thousand. There would be absolutely nothing to show for it in a couple hundred million years time.
I think some stone artifacts (cities, pyramids, roads) would still be identifiable in some cases. Excavation would be needed, of course.
Similarly, some of our concrete, glass and non-ferrous metal construction should survive a long, long time.