Establishing Quaternary as a formal international period/system

Despite being the most widely used unit in field mapping and having the greatest number of active researchers, the interval known as Quaternary is unique among the chronostratigraphic subdivisions of the Geological Time Scale (GTS) in having the most controversial definition and rank. After more than 100 years of debate, the base of the Quaternary is now widely recognized at ∼2.6 Ma, marking a dramatic and so-far irreversible shift to the ice-age-dominated world of oscillating glacial advances over the northern continents. In 2007, both INQUA and ICS proposed that the Quaternary be established as a System of the Cenozoic Erathem, with its base defined by the GSSP of the Gelasian Stage. To maintain strict hierarchy in the GTS, it is proposed that the base of the Pleistocene Series be lowered to coincide with the Gelasian Stage GSSP at ∼2.6 Ma.