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 fi eld 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).