ABSTRACT
Numerous crevice type caves formed along joint systems occur in the mountain slopes of the Polish Flysch Carpathians. They represent basic and often initial forms of deep rock landslides development. Tectonic features of four selected caves (situated in different parts of the Carpathians) were observed in order to study and determine relations between natural joint systems and landslide formation. The studies prove that the rock niches often represent the effect of earlier propagation of cracks and crevice type caves. Thus the niches are often formed before the main gravitational mass movements. The deep rock landslides develop in the prolonged process of stadial loading and unloading the shearing stress along the natural planes of original extension joints and induced relaxation joints in the rock massifs. Finally, this process brings to the marginal, breaking stress and gravitational movement of rock body separated by the widened crevices (often crevice type caves) from the massif.
