Geografie 1977, 82, 279-292
The Development of the Rock and Cave Features in Marlites in the Eastern Part of the Bohemian Cretaceous Basin
The rock forms and crack caves represent an important element of marlite relief in the Eastern part of the Bohemian Cretaceous Basin (Bohemian Plateau, North-Eastern Bohemia). They are the products of slope modelation in the valley sides or in sharp slopes of cuestas. In the development of rocky cliffs, the deep and lateral erosion of the main streams, later also of tributaries, and weathering of disrupted beds, took share (the origin of rock sharps, isolated rock towers, cave niches, rock perforations and small cavities). The most beautiful and largest rock features in the valley of Tichá Orlice river, above all in the part called Peliny near Choceň, can be found. (They are up to 35 m high, 50 m wide and run up to 30 m from the slope.) They occur as well in the valley of Divoká Orlice river and of its tributaries from right: Metuje river and others. The origin of the crack caves is in the slope movements of marlite blocks in sharp valley slopes and in valley edges. Enlarging of subterranean caverns can be made also by destruction and falling of disrupted rock (along the fissures and bedding joints). As well the suffosion has certain influence on the modelation of the surface in the neighbourhood of caves. The longest system of crack corridors is to be found in the cave called U Rozhraní (101.5 m lung), and in the cave Čertova díra near Bělá nad Svitavou (95 m). The deepest among them is the cave Průvanová near Hrádek (-38.5 m). The development of rock and cave features was taking place during the Quaternary (particulary in the Holocene period), some forms are evidently recent.
