The development of unconsolidated sedimentary coastal cliffs (Pobrzeże Kaszubskie, Northern Poland)

Abstract

In the course of fieldwork based on geological and landslide mapping and spatial analyses of map information at least 2 types of landslides were identified. Type I: simple landslides developed in homogeneous and undisturbed rocks, for instance – loams, clays and sands. This type of landslide includes many examples developed mainly on the stretch (segment of the studied area) approximately between 132.25 and 133.50 km and 128.50 and 129.50 km of the Polish coastline. Type II: complex landslides in which the movement and displacement of rock masses occurs under complex geological and hydrogeological conditions. The complex factors are determined by phenomena such as glaciotectonics, discontinuities of rock layers and thrust zones; the slip surface occurs at considerable depths, and sometimes several slip surfaces can be distinguished. These landslide types are located in the vicinity of Jastrzebia Gora and Rozewie, near km 134 and 131.5. Prediction of the formation of this landslide types is difficult. Even if long-term observations are available, the mass movement, variable over time, is difficult to interpret. It is clear that the changes are continuous, but occur with varying intensity. Proper recognition of the types of mass movement is crucial to establishing the appropriate methods to prevent their development.