● Official: written by Lovecraft himself or approved for publication during his lifetime
◎ Derleth's system (the Elements of Chaos, CoC TRPG, Arkham Society)
◇ Later fan-created works (Lin Carter, Pugmire, Delta Green, and others)
◆ Logical contradiction or time paradox: see "Note"
The timeline uses two parallel tracks, "cosmic chronology" and "Earth-relative dating." Units: billions of years ago (Byr) / millions of years ago (Myr) / thousands of years ago (Kyr).
