Origins of caves
Well, the brief answer to the question in the title is that caves form in various ways. Some due to tectonic or gravitational moves other as hollow places under congealed lava.
But most common in the world are karst caves. Another name for them is solution ones. The majority of, more or less, 160 Świętokrzyskie mountains’ caves are that type because of rich layers of limestone where karst process occurs.
Millions years old coral reef
But where limestone itself came from? To answer this question we need to go back in time around 400 million years to the Devonian period. In that time part of the Earth’ crust where today’s Świętokrzyskie lays was south of the equator under the sea or very close to it. Conditions were perfect for bloom of the underwater life. Ocean was full of animals, from the biggest predators of that time – armoured fishes, to sponges and corals. Skeletons of many of those were composed of calcium carbonate. After death their remains became layer of sediment that moved to the bottom of the ocean. For millions of years layer after layer mixed with inorganic material and turned into rocks in process called lithification. So in summary you may say that limestone were created from the remains of coral reef.
Limestone as a clue to the former sea level
Usually this kind of rock forms under water so it helps scientists determine the ocean level in a particular period of time. As mentioned, the underwater environment was full of life so we can find fossils of many sea animals. This can help to establish the exact date oflayers thanks to the presence of index fossils. These are the species that were common and widely spread around Earth and are connected to specific time. If we find such species, for example, in polish rocks and compare it to another place in other country where the species was also present and the age of rock was already established with different dating methods, it lets geologists quickly determine the age of those polish layers.
But limestone can be informative about the times when specific area was above sea level as well. It’s because that caves, cave formations and other such features are formed during the Karst process that takes place when the rock is a part of land.
This process happens when water enriched with carbon dioxide dissolves calcium carbonate – calcite. It creates hollow corridors known as caverns inside limestone. After water evaporates and carbon dioxide volatilizes, the calcite recrystallizes and can take a form of a stalactite, stagnate or cave pearl , for example.There also karst features on a surface of limestone from big valleys to sinkholes or small gulleys.
Paradise cave
Most of the Devonian caves are near Kielce. The most known is Paradise Cave that was caught off human interference for at least 8000 years. Thanks to lack of human activity stunning cave formations were created by nature. Stalactites grew long and covered cave roofs very densely. There are also variously shaped stagnates and other karst features.
You may listen to a tour guide describing what a particular shape of such cave formation may look alike, or just let your imagination do it for you. Visiting Paradise Cave requires online booking and payment in advance especially in the peak of a summer season. Since it is a nature preserve it is closed in winter time to implement protective measures.
I won’t share any pictures with you because I prefer to look at such wonders with my own eyes. Especially for the first time. I encourage everyone to do the same. But if you really need to take a look visit official cave’s page and open a gallery (“galeria” in polish).
Other caves in the Holy Cross Province
In Kielce city Kadzielnia preserve and its surroudings has the highest number of caves in the Swiętokrzyskie Mountains, 25, and some of them can be visited too.
Most of caves in the province were found during mining of limestone in quarries but a few have natural entrances. For example, as seen in the first picture, Hell Cave in Skiby near Chęciny, the town with the famous castle.
Caves from time when dinosaurs ruled the Earth can be found in the Świętokrzyskie province as well. There is a Jurassic cavern aslo called Hell in Milechowy. Limestone from that period in the Świętokrzyskie holds deposits of striped flint. It is a unique mineral that doesn’t occur anywhere else in the world.
Why so many caves and rocks have names associated with hell or devil? Answer to this question soon on the blog.
Świętokrzyskie also has the biggest cave system outside the Poland’s highest Tatry mountain range. It is unavailable for anyone apart from professional cavers. Placed in Jaworznia in the preserve Chelosiowa Jama (Den of Cheloś). Cave corridors here reach almost 4km.
Beside the Świętokrzyskie Mountains there are also caves in Ponidzie, the southern part of the Świętokrzyskie voivedship. These formations are in gypsum which is subjected to the karst process in the same way as limestone. The highest number of such caverns is in Skorocice preserve that has 26 of them.
As you see the Świętokrzyskie province can be quite fascinating, not only for professional geologist, but also for those who appreciate wonders of nature in form of rocks and caves.