Figure 2. Age-probability density plot of ⁴⁰Ar/³⁹Ar single-crystal incremental heating isochron ages for all analysed grains, combined across all samples.

The representative weighted-mean age for the CI eruption from this population is 39.85 ± 0.12 ka (95% confidence level, including error in J, the neutron-fluence parameter). MSWD, the ‘mean square of weighted deviates’, is a reduced chi-squared statistic that should be approximately unity if the analytical errors are properly estimated and the observed scatter is due to the stated uncertainties. Errors in individual data points (the isochron ages) are shown at 1σ.