Jaskinia szczelinowa Diabla Dziura w Bukowcu (Pogórze Rożnowskie, Karpaty zewnętrzne) jako inicjalne stadium rozwoju głębokich osuwisk w Karpatach fliszowych

Abstract

Crevice-type cave Diabla Dziura in Bukowiec (Rożnów Foothill, Outer Carpathians) as an initial stage of deep-seated landslides development in the Flysch Carpathians (S Poland).S u m m a r y. Diabla Dziura cave—the deepest pseudokarst cave (42 m) of the Polish Outer Carpathians (Rożnów Foothill) represents a tension crack of the initial stage of landslide development. Several types of gravitational movements — spreading, toppling, rotational — have been observed in the cave. They will gradually evolve into a landslide. The joints system of the cave is featured by zonality. All joint sets (L, T, D1, D2) occurring in the massif are present in the complete relaxed, upper part of the massif (to the depth 10–12 m), whereas the set D2, parallel to the mountain ridge stretching, predominates in the deeper part. To the depth 25 m the joint surfaces are often slightly curved, deeper they are straight and even. The main passages of the cave represent polygenetic joints, developed due to tensional stresses operating within the ridge. Curved shape of the joint surfaces is an effect of correlation between foundations of jointing (combination of tectonic and denudational-unloading stresses) and a way of their opening, generated partly by tectonical extension, partly by denudational factors in the upper part of the ridge. Also the lithological character of the rock massif (thick-bedded sandstone) could play a significant role in formation of these curved surfaces.