"global chronostratigraphic units"
   (Eon) Phanerozoic Eon (541.0 Ma - present)
     (Era) †Paleozoic Era (541.0 - 251.902 Ma)
       (Period) †Ordovician Period (485.4 - 443.8 Ma)
         (Subperiod) †Bala Sub-period
           (Epoch) †Caradoc Epoch
             1 (Stage) †Costonian Stage
             2 (Stage) †Harnagian Stage
             3 (Stage) †Soudleyan Stage
             4 (Stage) †Longvillian Stage
             5 (Stage) †Marshbrookian Stage
             6 (Stage) †Actonian Stage
             7 (Stage) †Onnian Stage