Ondříkovický pseudokrasový systém

Ondříkovický pseudokrasový systém is a protected natural monument safeguarding one of the most remarkable cave systems in the Czech Republic, located in the municipality of Frýdštejn, between the settlements of Roudný and Ondříkovice, about 5 km north of Turnov, right on the northwestern edge of the Český ráj Protected Landscape Area.

What's actually hiding behind this name?

Despite its name suggesting a pseudokarst, the area actually protects a system of true karst — one of the most significant in the entire Czech Republic. The rock here consists of Turonian-age sandstones, in which grains of sand were cemented together by a calcareous (limestone) binder. It was the dissolution of this limestone cement by water that created the caves, sinkholes, and springs typical of classic karst, rather than the pseudokarst processes originally assumed when the site was named. This discovery led researchers to propose a new name for the area — Kras Turnovské pahorkatiny (Karst of the Turnov Hills).

Four parts of one system

The protected area comprises four interconnected features in the valley of the Vazovecký stream: the Bartošova pec cave, the Ondříkovický ponor sinkhole, the Ponor u Roudného sinkhole, and the Ondříkovické propadání collapse feature. The largest and best known of these is Bartošova pec — a cave roughly 225 meters long, formed along rock fractures widened by the dissolution of the limestone binder in the sandstone. Ondříkovické propadání is a lateral sinkhole ending in a massive collapse with a sink in its floor, through which water disappears underground before resurfacing after flowing through the system of subterranean channels.

A history of protection

The natural value of this site was already recognized back in the 1960s — Bartošova pec and Ondříkovické propadání were granted protected natural feature status in 1965. The area received its formal status as a natural monument in its current form on May 23, 2001. The monument itself covers a modest area of 0.8669 hectares, surrounded by a buffer zone of 12.6721 hectares, which helps safeguard not just the caves and sinkholes themselves but also their immediate hydrological and geological surroundings.

Why this place matters

Ondříkovický pseudokrasový systém is a striking example of how nature can surprise even scientists — a site named after a phenomenon that, as it turns out, doesn't actually occur here in the form the name suggests. For anyone interested in geology and speleology, it's one of the key points on the karst map of the Český ráj region, illustrating how water carves an underground landscape over thousands of years, even in rock that at first glance doesn't look like typical karst terrain.

Frequently asked questions

Where exactly is Ondříkovický pseudokrasový systém located? In the municipality of Frýdštejn, Jablonec nad Nisou district, Liberec Region, between the settlements of Roudný and Ondříkovice, about 5 km north of Turnov.

What is the largest cave in the system? Bartošova pec, roughly 225 meters long — the longest and best-known part of the system.

Is it really a pseudokarst? Not quite — research has shown it's actually true karst, formed by the dissolution of limestone binder in Turonian-age sandstones, which is why the name Kras Turnovské pahorkatiny has been proposed for the area.

Since when has the area been protected? Bartošova pec and Ondříkovické propadání have been protected since 1965, and the area gained its current natural monument status on May 23, 2001.