THE PLEISTOCENE AND THE QUATERNARY: A STUDY IN OPTIONS

In June 2009 the International Union of Geological Sciences ratified a proposal from the Innternational Union for Quaternary Research, or INQUA, following its approved by a majority of the International Commission on Stratigraphy, to give the Quaternary formal status as a System/Period. In this proposal, the base of the Quaternary was established a priori in the Gelasian GSSP at 2.58 Ma, in accord with the most recent view of INQUA as to when “glacial climates” began. In order to conform to this new Quanternary, however, the INQUA proposal also redefined the Lyellian Pleistocene by moving its lower boundary from the base of the Calabrian Stage (dated to 1.81 Ma), where it had been located since 1948, to that of the Gelasian Stage -- thereby increasing the duration of the Pleistocene by 44% .What the IUGS apparently failed to consider in approving this “adjustment” was its impact on the many disciplines that employ the Plio-Pleistocene chronostratigraphic boundary, rather than the concept of Quaternary climate, as a fundamental metric in their research. Opposition to the drastic change was immediate and widspread in the affected disciplines, with many researchers refusing to employ the new definition With this controversy before us, we here examine the availability and legitimacy of options in using the Geological Time Scale. A crucial fact is that the authority of the IUGS to define the properties of the GTS is based on a relatively recent consensus among earth scientists, rather than any official directive, to use the version of the time scale published under IUGS auspices.. It follows that adherence to IUGS decisions in this regard is still a matter of consent by the users. This is demonstrated in a canvass of journals that publish research in the disciplines most affected by the recent decision, in which we found that none require their manuscripts to follow any particular version of the GTS. In addition, several journals are making a point to inform authors who may be confused by the current dispute, that they have the option to agree or disagree with the revised Plio-Pleistocene boundary, whatever their views on the Quaternary.