Chlumská hora
Description
Chlumská hora (650 m a.s.l.) is another noticeable table rock in the region of Manětín. hora is a relict of a tertiary lava sheet (created by porous trachybasalt and nefilinitic basanite) that covered low resistant Carboniferous sedimentary rocks (mainly sandstones and claystones). The lava sheet protects the sedimentary rocks against weathering and removal. That creates the typical form of table rock – flat hilltop (ca 3, 5 kilometres long and 400 meters wide) that is elevated above the surrounding relief and is bounded by steep rock walls. The lava plateau is disintegrated by longitudinal joints which are mostly parallel with edge of the plateau. Cracks, trenches and pseudo-karst depressions create due to gravitational processes along these joints. Big blocks of the lava plateau slide then over the Carboniferoes sedimentary rocks underlying the lava sheet along the failure surface. The disintegration of the blocks continues and extensive block accumulations are created. The block accumulations border the rock walls of the whole table rock (fig. 1).