Including the tail end of the 60s in the discussion is a bit of a cheat, and for the change in the country’s zeitgeist, I’d start no earlier than Nixon’s reelection. For pop culture purposes, the 70s thus really probably spanned from around 1973 to 1980. E.g., the Beatles broke up in 1970, but you wouldn’t call them a 70s band. But Wings, you would.
As someone pointed out in a thread about the “creepy Seventies”: