Original paper
Removing inconsistencies in Neogene and Quaternary timescale terminology
Head, Martin J.
Newsletters on Stratigraphy (2026)
112 references
published online: Jun 24, 2026
manuscript accepted: May 28, 2026
manuscript revision requested: Mar 4, 2026
manuscript received: Dec 18, 2025
Abstract
Over the past 15 years, changes to the formal subdivision of the Neogene and Quaternary systems have affected timescale terms used in paleoclimate and other studies. One change, triggered by the defining of the Quaternary System in 2009, simultaneously lowered the base of the Pleistocene Series to that of the Quaternary, effectively by 780 kyr. Accordingly, the “mid-Pliocene warm period”, a warm phase centred around 3 Ma and serving as an important near-future climate analog, was no longer in the middle of the Pliocene Series but remained in that of the Piacenzian Stage (3.60–2.58 Ma). It is now more properly known as the “mid-Piacenzian warm period”. Furthermore, the “mid-Pleistocene transition”, representing a fundamental change in the mode and rhythm of climate cycles, was no longer centred in the mid-Pleistocene. Given that this transition was the rationale for defining the Early–Middle Pleistocene subepoch boundary formalized in 2018, the term “Early–Middle Pleistocene transition” became more apt. With the formalization of subseries for the Quaternary and Neogene during 2018–2021, capitalization for the positional terms they bear (Lower Holocene, Upper Pleistocene, etc.) is needed to indicate their status as precisely defined Geological Time Scale (GTS) units. The adoption of these terms and conventions has nonetheless been slow. Meanwhile, Paleogene subseries remain informal as acknowledged by lowercased positional terms (lower Eocene, upper Oligocene, etc.). The GTS’s many inconsistencies are reviewed to give context to this anomaly. The Anthropocene epoch, while not presently an official timescale unit as indicated by the lowercased “epoch”, references a unique shift in the human enterprise beginning in the mid-20th century, whereas the term “anthroposphere” encompases the wider range of significant human presence over the past ~50 kyr. The Pleistocene, Holocene and Anthropocene are timescale terms whereas the ecosphere and anthroposphere are principal components of the Earth system, yet despite these conceptual differences the Anthropocene and anthroposphere are frequently conflated. The correct use of terminology is critical for precise and unambiguous communication in paleoceanography, paleoclimate studies, and all other branches of scholarship that reference geological time and its stratigraphic record.
Keywords
Geological Time Scale • stratigraphic terminology • mid-Piacenzian warm period • Early–Middle Pleistocene transition • Anthropocene • anthroposphere