The Pliocene era was three to five million years ago, not 650,000. I think the Welsh bluestone (dolerite and rhyolite) really was deposited (volcanically) during the Pliocene, but I’m not sure.
“Christianity has been around less time than Stonehenge” – well, duh. I think Antiquarian meant to say “Christianity has been around less time than* it took to build* Stonehenge.” Now that’s pretty amazing (and equally true).
I haven’t read the book but I watched a 45-minute video of a presentation she did on it and it absolutely amazing. I even had a brief e-mail conversation about Quipus and the Nazca line -with me being Peruvian- and she was incredibly nice and gave me even more information.