Fig. 3From: Review of the Early–Middle Pleistocene boundary and Marine Isotope Stage 19Reproduction of Chart 1 of Osborn (1900), an early example of the tripartite subdivision of the Pleistocene along with other Cenozoic series and their subdivision. The word Pleiocene, from the Greek pleiōn (Latinized as plio-), is a rare variant spelling of PlioceneBack to article page