Evolution of key mantle parameters for a Type I evolution (black) and a Type II evolution (blue). Venus’ age is demarcated with a dashed vertical black line. Note that after about 5.5 Gyr, the Type I evolution begins to exhibit Type II–like behavior (a ramp-up in viscosity, a ramp-down to 0 in the upper melt fraction, and a subsequent total loss of water in the atmosphere). Parameter choices for these evolutions can be found in Table 8.