Not sure if you're still soliciting answers for this question, but I found Creating Better Futures: Scenario Planning as a Tool for a better tomorrow by James A. Ogilvy was the book that led me to future studies, although I'm not sure how useful that would be in addressing the question you had about naming pivotal points in order to identify new eras. Incidentally, I would be curious to see what kind of methods you would have used to answer this original concern of yours!
National Research University Higher School of Economics
University of Aberdeen
Central European University
Diego S Maranan
University of Plymouth