14 show caves of the Czech Republic: VISITOR RULES IN EFFECT FROM NOVEMBER 22, 2021 More
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Na Pomezí Caves

Characteristics / Evolution of the Caves

DEVELOPMENT OF THE NA POMEZÍ CAVES

The Na Pomezí Caves are the longest and most extensive karst system formed in crystalline limestones (marbles) in the Czech Republic. The high chemical purity of the crystalline limestones, favourable inclination of beds and substantial tectonic jointing with several variably oriented systems of fissures and faults were the most decisive factors for the development of the caves. The location of these limestones above the base level of erosion was also an important factor.

Karst processes forming the Na Pomezí Caves started in the Tertiary, in a period of rainy, warm to subtropical climate. Seeping water with its corrosive and erosive activities widened cracks in limestones and created the first sections of fracture caves, which gradually joined together, countersunk, formed contiguous trails for underground streams, and in this way they could be more quickly expanded to larger cave areas. At the beginning of the Quaternary the development of the cave system was also influenced by cooling and by arrival of ice periods (glacials). Frost penetration of the limestone massif occurred – it was torn by ice in cracks, in some parts to a depth of 20 m. Full disintegration of limestone beds and breakdown of blocks occurred at higher levels of caves and lower levels (e.g. Královský dóm [Royal Dome] and Dóm chaosu [Dome of Chaos]) were buried.

Two significant levels are known in the caves. The upper level is disturbed by weathering; the lower one has preserved signs of sculpting by underground streams. The contour system documents that caves developed in dependence on recession of the Vidnávka River valley. High fissure corridors that are at several places of crossing of tectonic zones widened to dome-like spaces formed there.

It is also remarkable that some forms and shapes of the Na Pomezí Caves show characteristics known in high-mountain karst areas. The polygenetic and polycyclic development is documented by the whole process of development and variety of cave shapes.

The Na Pomezí Caves are not an isolated cave system, but part of the so-far little-known karst underground running through the limestone massif of the Smrčník Hill (798 m a.s.l.), where ten caves have been registered so far and others have been destroyed in the local quarry during mining for limestone.