I think Chapter six addresses some of the issues raised, including the rationale for the 44TYA. None of this appears to be a 'code'; is a the measurement of a feature which indicates why each monument was built at its location -as I understand it. Yes, there is no evidence of earlier civilizations. I've read arguments about total annihilation related to the Atlantis argument. One question raised in the book is the need for infrastructure; economic, social, technological, etc. existing prior to the planning of a large monument.