Lithological conditioning of landslides and climatic changes with examples from the Beskidy Mts., Western Carpathians, Poland

Abstract

The paper presents the results of geomorphological, geological and palynological investigations carried out in the area of Szymbark and Koszarawa, Beskid Niski and Beskid Z: ywiecki Mts., respectively (Western Carpathians, Poland). The examined sites, although located relatively far apart, represent the parts of the Polish Flysch Carpathians, where landslides affect the landscape pattern and cause damages to land resources, properties and people dwelling there. This study is based on a comparative approach regarding the lithological setting (the same lithostratigraphic unit present in both sites), types of inventoried landslides and climatic triggers. The relation between particular rock complexes and climate control on landslide development is discussed. Lithologic and tectonic controls are very important in the Beskid Niski region, where distribution of landslides corresponds with a pattern of weak shales series and fault zones. In the Beskid Z: ywiecki region, the sequence of particular rock series, especially thin shales underlying massive sandstones, is more critical for mass movements. Landslides with complex style of activity predominate in these regions and, very likely, they contribute to slope transformation at present. In particular, the investigations focused on the flow-like landslide form at Maslana Góra Mt. (Beskid Niski Mts.). This form is the outstanding fea- v ture due to its size. Moreover, it well illustrates the environmental changes that are related to wet climate, and exemplifies landscape sensitivity. Organic sediments filling up two landslide depressions at Masvlana Góra Mt. were 14C dated and palinologically analysed. The older depression was formed at the transition of Subboreal to Subatlantic, that coincided with maximum distribution of Abies alba in the area. Time of formation of the younger depression, dated at ca. 1500 yrs BP, is related to the increase of fluvial activity in the Upper Vistula basin.