As a question, if there was a actual globe spanning technological civilization like 20K years B.C then what signs would there be?

i am not in anyway suggesting this exists, I am just asking that is a civilization let’s just say, maybe 100 years more advanced then our own, existed 20 to 30 thousand years ago, then would it be insanely easy to realize that, or would it be Difficult to detect and find, how would this effect geology, and biology and our view, of the past