Kozelka
Description
Kozelka (660 m a.s.l.) is one of the table rocks in Manětínská basin and we can find here a lot of geomorphic forms created by gravitational processes. The table rock Kozelka is created by a tertiary lava sheet (porous trachybasalt and nefelinitic basanite) that covered low resistant Carboniferoes sedimentary rocks – sandstone and claystone. The sedimentary rocks are protected by the lava sheet against weathering and removal. So the platform is elevated (100-150 m) above the surrounding relief and the flat hilltop is bounded by steep rock walls. The flat hilltop is ca 1 kilometre long and 30-150 meters wide. The plateau is disintegrated by longitudinal joints which are mostly parallel with edge of the plateau. The joints are extended by gravitational processes and the edge of the plateau is fringed by blocks displaced from their original location. Cracks and trenches are results of these processes. The cracks suggest sinkholes which are typical for karst area. That´s why these forms are called pseudo-karst depressions. The displaced blocks slide then over the underlying Carboniferoes sedimentary rocks. The block slides often uncover the rock walls which are then segmented into rock towers (for example Plzeňská tower, photo 4), needles (Nečtinská jehla, photo 3), cliffs (photo 2) and gates (photo 1). The disintegration of these forms continues and extensive block accumulations are created. The block accumulations border the rock walls of the whole table rock (fig. 1 - 3).