Mass growth history for various radial shells, normalised to the final value as in Fig. 2, for different values of a_g and γ. The formation epoch a_g changes the growth of the individual shells and the overall growth pattern of the halo. This can also be seen in the half-mass time of the shells indicated with a plus on every curve. The parameter γ mostly influences how individual shells grow. This is seen as we change γ from 2 to 4 (left vs. right panels): only a small effect is seen in the overall growth of the halo, but the inner shells grow on much shorter timescales than the outer shells.