stratigraphic intervals
   (System) †Cambrian (541.0 - 485.4 Ma)
     (Series) †Upper (497 - 485.4 Ma) see Series Furongian Series (497 - 485.4 Ma)
       1 (Stage) †Trempealeauan
       2 (Stage) †Franconian
       3 (Stage) †Dresbachian