Time Constraints and Tie-Points in the Quaternary Period

The Quaternary Period, by virtue of the near-surface preservation and widespread accessibility of its environmental archives, provides fundamental data to test models of climate change, sea level variation, geomagnetic field variation, human and faunal migration, cultural evolution and more. Spatially disparate records of past environmental change with subannual to multimillennial temporal resolution are compared to examine the relative timing of events and consider causal mechanisms, and this analysis puts great demands on the chronological tools available. Highly precise and accurate age estimates are required, in concert with correlative tools or chronostratigraphic markers. We focus on radioisotope chronometers (e.g. U-series, 40Ar/39Ar and 14C) and illustrate their application in three vignettes for which different strategies are required: (1) the dramatic decades of the last deglaciation (~14.7 ka), (2) before and after one of the last geomagnetic excursions (~41 ka) and (3) the glacial–interglacial cycles of the Middle Pleistocene (125–780 ka).