Figure 2. Hypothetical relationships among the irreversible cooling of the Earth's surface, character of volcanism, explosive volcanic maxima, major periodic coolings and mantle- plume volcanic maxima, warming, and geodynamic stages [Chumakov, 2001b]. g = glaciations, A = Archean, PR = Proterozoic, R = Riphean, V = Vendian, PH = Phanerozoic.