Moseley et al. (Reports, 8 January 2016, p. 165) postulate an increase in dissolved thorium isotope Th-230 with depth below the water table as the explanation for the differing ages of Termination II. Flow of geothermal water through the Devils Hole caverns precludes this explanation. Deposition of younger secondary calcite into the initial porosity of the calcite comprising their cores is a plausible alternate explanation.