Rola grawitacyjnych ruchów mas skalnych w rozwoju progu zachodniej części Beskidu Małego

Abstract

The Beskid Mały is descending to the north by a clear structural edge on the face of the godulska overthrust. The height of the edge above the surface of Pogórze Śląskie reaches 500 m. Geological and geomorphological researches were earned out and map of relief (Fig. 1) and of landslides on the background of geological structure (Fig. 2) as well as maps and cross-sections of landslides were drawn (Fig. 3, 4, 5, 6, 7, 8). The total area of landslides is 7,5 sq km what is about 50% of the edge surface. Deep rotational landslides were fonned on shales and sandstone-shale beds covered by thick-bedded godulskie sandstones. The biggest landslides are in transversal zones of displacement faults along which the material is cracked, with many fissures so it is pliant for displacement. Tectonical predispositions of the basement decisively influenced creation and development of landslides. Landslides in their initial parts have the best preserved niches, their bodies are quickly damaged. Slope landslides are developed from the lower to the upper parts. They consist of different in time slides and majority of deep landslides were formed in the Holocene as landslide bodies were displaced onto solifluctional covers. Development of gravitational movements of rock masses led to creation concave step-like slope on the edge of the Beskid Mały.