"global chronostratigraphic units"
   †Precambrian (4600 - 541.0 Ma)
     (Era) †Hadean Era see Eon Hadean Eon (4600 - 4000 Ma)
       1 (Period) †Pre-Nectarian Period
       2 (Period) †Nectarian Period
       3 (Period) †Imbrian Period