  We study the morphological evolution of surfaces during ion sputtering and we
compare their dynamical roughening with aeolian ripple formation in sandy
deserts. We show that the two phenomena can be described within the same
theoretical framework. This approach explains the different dynamical behaviors
experimentally observed in metals or in semiconductors and amorphous systems.
In the case of ion erosion, we find exponential growth at constant wavelength
up to a critical roughness $W_c$. Whereas, in metals, by introducing the
contribution of the Erlich-Schwoebel barrier, we find a transition from an
exponential growth to a power law evolution.
