Figure 1. Distribution of glaciations through geologic history. Solid horizontal lines, glacial epochs (glacioepochs); their length is proportionate to the maximum spread of glaciation in a given epoch (in the Phanerozoic, to paleolatitudes, and in the Precambrian, to the number of continents). Dashed line outlining glacioepochs shows glacial periods (glacioperiods). Dotted lines, inferred glaciations and ages. A = Archean, PR = Proterozoic, R = Riphean, V = Vendian, PH = Phanerozoic. MC = Mesozoic cooling (modified after [Chumakov, 2001a]).