Pleistocene The lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama (C2r) chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils: "Discoaster pentaradiatus" and "Discoaster surculus". The Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the start date of the Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. The modern continents were essentially at their
Middle Pleistocene Quaternary Stratigraphy's preferred GSSP proposal for the age/stage that should replace the Middle Pleistocene subepoch/subseries. Until the Chibanian is ratified by the IUGS, the Chibanian will remain an unofficial informal, proposed stratigraphic division and "Middle Pleistocene" remains the provisional or quasi-formal name, used by the IUGS on the International Chronostratigraphic Chart for 2018. Middle Pleistocene The Middle Pleistocene is a subdivision of the Pleistocene Epoch, from 781,000 to 126,000 years ago (781–126 ka). It is preceded by the Calabrian stage, beginning with the Brunhes–Matuyama reversal, and succeeded by the Tarantian stage (equivalent ot the Late or Upper Pleistocene), taken as