Figure 2. Magnetic zone lengths in various time intervals: (a) 23-0 Ma, Neogene; (b) 65-23.3 Ma, Paleogene; (c) 169-66 Ma, Cretaceous-Mid-Jurassic; (d) 250-169 Ma, Mid-Jurassic-Triassic; (e) 362-250 Ma, Permian-Carboniferous; (f) 545-363, Devonian-Cambrian; (g) 1700-545 Ma, Vendian-Riphean.