Fig. 4.

Comparison of our Siple Dome ash record with the global volcanicity index of Bryson and Bryson (13) (Upper) and the GISP2 volcanic sulfate of Zielinski et al. (15) (Lower), each averaged over 1 kyr. The Siple Dome ash magnitude ranking is from ref. 6; the Bryson volcanicity index has been renormalized. The Bryson curve does not extend back beyond 35 ka because of the limitation of radiocarbon dating. All three curves indicate that the greatest activity was ≈10 ka during the main deglaciation of the early Holocene.