Figure 2.

Single-grain and weighted mean ²⁰⁶Pb/²³⁸U dates for Central Basin bentonites. The height of the single grain rectangles (light blue) is proportional to the 2σ uncertainty of that measurement. The weighted mean of each sample set is shown as a black line, with translucent grey bands either side representing the 2σ uncertainty. The combined mean age for sample ‘Bk1’, ‘Lk1’, and ‘SvN’ (equivalent to sample ‘Am1’¹³) is shown as a red dashed line through samples with 2σ uncertainty shown as a translucent red band. Astronomically calibrated Palaeocene stage boundaries²⁵ are shown on the right.