Deep-seated landslides . Pseudokarst . Rotational slide . Spreading . Statistics . Toppling

Mass movements can be investigated usually only from the surface or, more in-depth, indirectly by geophysical methods and by spot drilling. Crevice-type caves allow us to visit and observe the inner environment of the slope deformations. Such caves are typically composed of systems comprising long and high joint-predisposed corridors, enabling us to investigate geological outcrops hundreds of meters long and tens of meters deep within the landslide mass. The present paper shows the diversity of particular gravitationalmovements influencing the vast slid rock blocks, which seem to remain intact and consolidated within the landslide body. By use of geological compass measurement and statistical evaluation, we detect complexmovementmechanisms in most investigated cases, often without any impact on the topography above. The results prove the existence of a great difference between the overall behavior of the deformation and its individual rock blocks, as well as discrepancy between movement mechanisms detected in crevice-type caves and by formal investigation. Furthermore, this paper discusses the related horizontal rotation and subsidence movements documented by previous studies. We can conclude that most deformations are complex.