I missed this post since it was never a reply to me. No link here.
The only person who think’s “Adam’s calendar” is 75,000 years old is one guy, a South African pharmacist, who provides no evidence of his claim.
Actually he decided it measured the rise of Orion’s Belt first then back calculated to when Orion’s Belt actually aligned with some of the stones.
This is the kind of junk science that should be ignored.
The next calculation was presented by a ’ master archaeoastronomer ’ ( Bill Hollenbach? (8)) who unsurprisingly, wishes to remain anonymous for ‘fear of ridicule by the academic fraternity’. The calculation was apparently based on the rise of Orion and suggested an age of at least 75,000 years. (2)