stratigraphic intervals
   (System) Quaternary (2.58 Ma - present)
     (Series) †Pleistocene (2.58 - 0.0117 Ma)
       1 (Subseries) †[upper] (0.129 - 0.0117 Ma)
       2 (Subseries) †[lower] (2.58 - 0.774 Ma)