Evolution of the five different ice-dust mixtures with horizontal insolation. The occurrence of collapse events with different sample compositions is noticeable (online movies). Samples with a 33 vol% and 50 vol% water ice content show a continuous alteration of their shape until the end of the sublimation activity and formation of talus at their base. At a 25 vol% and 20 vol% water ice content, single events occurred in the form of cliff collapses exposing fresh material on the surface (see Fig. 5B). After 5.5 h and 3 h, respectively, no further alterations on the surface were visible. The bright areas in the upper right corner of the images with 20 vol% water ice are reflections of a light source in the laboratory on the observation window of the sublimation chamber.