  We analyze the phenomenon of axion fragmentation when an axion field rolls
over many oscillations of a periodic potential. This is particularly relevant
for the case of relaxion, in which fragmentation provides the necessary energy
dissipation to stop the field evolution. We compare the results of a linear
analysis with the ones obtained from a classical lattice simulation, finding an
agreement in the stopping time of the zero mode between the two within an
${\cal O}(1)$ difference. We finally speculate on the generation of bubbles
with different VEVs of the axion field, and discuss their cosmological
consequences.
