The interaction of energetic particles with frozen gas layers figures prominently in a variety of astrophysical situations and also in T Tau nebulae. This is due to the large fluxes of particles ejected by these stars during their continuous flaring activity and the observed presence of ice grains, at least around the very young star KL Tau. To better understand the problem, a brief description is given of the most important physical processes occurring during ion bombardment of frozen gas layers (mantles). The transfer of energy which is still in the electronic system from a proton to atoms and molecules may take place through the generation of phonons that may establish transient local quasi-thermodynamic equilibrium in a cylindrical region 50 A wide around the track of the impinging ion if energy remains confined for at least 10 to the -12th sec. It is noted that the occurrence of such an equilibrium can give rise to interesting consequences; the two principal effects of the energy deposition of fast ions in a frozen gas layer are ejection of atoms or molecules and the chemical modification of the layer itself. These two effects are discussed in detail.