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by Barrin92 1065 days ago
There would be no evidence on the surface of the earth, but just as there's characteristic fossil layers in the ground there would be evidence in the sediment. Right now about 30 billion tons of concrete are used by our species every year. If there were industrial civilizations of that scale, you'd have a whole stratum of very obvious artificial origin between the rocks.

Also some leftovers of the nuclear industry. Enriched Uranium does not occur in nature but U235 has a half-life of about 700 million years. So remnants of our nuclear activity will be detectable for a long time.