Gravitationally Induced Non-karst Caves in the Polish Outer Carpathians

The Outer Carpathians, formed of siliciclastic-clayey rocks, abound in non-karst (pseudokarst) caves. In their Polish part, 1646 such caves with a total length of 27,857 m have been recorded up to July 2021. The longest Jaskinia Wiślańska cave reaches 2275 m, whilst 43 caves are longer than 100 m and 31 caves are 15 m deep or more (up to 60 m). Most of them are genetically related to slope gravitational deformations, but there are also caves—principally only several metres long—formed due to non-uniform weathering of sandstoneSandstone cragsCrag. Amongst the gravitationally induced Carpathian caves, several types can be distinguished. In the morphogenetic classification, considering the succession of processes, three types of caves are recognized: initial caves (preceding the main slope failures), subsequent caves (formed during the main slope deformations) and intermediate caves. Regarding the geomechanic criterion also three principal groups are discriminated: dilational caves (formed due to simple tensional fracturing), dilatancy caves (related to a fissure macrodilatancy) and boulderBoulder caves (developing within very strongly deformed slopes). Four examples representing various morphogenetic and geomechanic types of caves are described in this chapter. The gravitationally induced caves have been formed since the Late Glacial, when the destruction of slopes started along with permafrostPermafrost degradation, but have fully developed and transformed during the Holocene, with several periods of intensification connected with climate changes (moistening).