On the dumps of the Cracow Soda Factory there occur molluscan assemblages comprising 13 taxons. The assemblages display a succession connected with three phases in the development of vegetation, which occurred when the slopes of the dumps were getting overgrown. The succession phases correspond to the assemblage with Helicella obvia, the assemblage with Pupilla muscorum, and the assemblage with Helicella incarnate, respectively. A biometrical analysis of populations of 7 snail species has shown that the populations do not differ from those occurring in natural habitats. The diversity of the assemblages is very high: xerophilous and hygrophilous species can be found together in one assemblage.