Yes, I've heard of refined glass as being one of the indicators. However, pretty advanced technologies like pottery would not have made it. I can't be sure thi

Yes, I've heard of refined glass as being one of the indicators. However, pretty advanced technologies like pottery would not have made it. I can't be sure this [1] is the original article I was remembering but it might be an interesting read anyways. I am sure the study authors approach the subject with far greater care than I could. 1. https://www.scientificamerican.com/article/could-an-industrial-prehuman-civilization-have-existed-on-earth-before-ours/ https://www.scientificamerican.com/article/could-an-industri...