Geomorphologic evolution and landforms

At the end of the Variscan orogenetic processes (Permian period) the Bohemian Massif was a mountainous terrain similar to today Alpine mountains. Intensive denudation processes reduced the mountain terrain to a planation surface (flat terrain or slightly undulating landscape) already during the Permian. For most of the Mesozoic we have poor evidence of geomorphic evolution of Czech landscape.

The marine transgression during the Late Cretaceous was a milestone for contemporary landforms. This transgression caused burial basement rocks by a thick pile of clastic deposits. We call the area covered by this deposits the Bohemian Cretaceous Basin. Till today it is flat lowland where the important agricultural activity is situated. The sandstones are dominant rocks in this area and later they were sculptured by weathering ans erosion in famous "rock cities".

Orogenic processes in the Alps and Carpathians induced major tectonic rejuvenation in the Bohemian Massif. We call it neotectonics and it led to the formation of the characteristic horst-and-graben structure of the Bohemian Massif with an elevated rim of mountains enclosing a rather stable or slightly uplifted Bohemian Basin. The Tertiary in Central Europe was characteristic by a warm and humide climate, deep weathering  formed kaolinitic mantles (e.g. nort of Pilsen where the kaoline is mined). The most important stage in evolution of caves in the Bohemian Massif occurred also during the Tertiary. Neotectonics during the Terciary caused also massive  massive volcanic activity which formed the Ohře/Eger rift at the southeastern foothills of Krušné hory (Eger Mts.). Majority of the volcanic products were removed by erosion, but the remnants of sub-volcanic bodies form characteristic landscape in the NW and N parts of the Czechia (e.g. České Středohoří and Doupovské hory).

Main features of recent major valley networks were established during the Late Tertiary but still they were a bit different than today's network, e.g. south Bohemian rivers flew to the catchment of upper Vltava which was drained off to the Alpine Foreland and not to the north to Labe River.

The eastern part of the Czechia formed by the Carpathians started its subaerial evolution not until the Miocene and gross land surface of the flysch Outer Western Carpathians is hardly older than 15 Ma.

Further reading:

Pánek, T., Kapustová, V. Long-Term Geomorphological History of the Czech Republic. In Pánek, T. a Hradecký, J. (Eds.) Landscapes and Landforms of the Czech Republic. Switzerland: Springer International Publishing, 2016, p. 29-39.