The Punkva Caves are located in the northern part of the Moravian Karst. They lie in the canyon of Pustý žleb, which forms part of the Vývěry Punkvy National Nature Reserve and the Moravian Karst Protected Landscape Area. The Macocha Abyss opens into them. According to the Cave Administration of the Czech Republic, the Moravian Karst is the largest and most significant karst area in the country and lies north of Brno.[2]
The Moravian Karst and the formation of the caves
The Moravian Karst covers an area of 94 km² of Devonian limestone, is 25 km long and 3–5 km wide, and forms part of the Drahany Highlands. More than 1,100 caves and abysses have been recorded there.[2] They formed through the gradual dissolution and erosion of limestone by rainwater and underground streams. The Punkva Caves are part of the system of the Punkva stream, where the water emerges or used to emerge. The headwaters of the Punkva disappear into sinkholes near Holštejn and Sloup and flow through Amatérská Cave, the longest cave system in the country, whose known passages measure 33 km. The Punkva then re-emerges at the bottom of the Macocha Abyss and flows through the active branch of the Punkva Caves into the canyon of Pustý žleb, which is up to 120 metres deep.[2]
The caves formed in several levels, and ceilings easily collapsed at the intersections of geological faults. This is how both the Macocha Abyss and the tall Reichenbach Dome were formed. Characteristic features include chimneys up to 80 metres high; the Tunelová chodba passage is an example of a pressure-eroded tube, and the underground fluted grooves are also of interest.[2] Under normal water levels, the other parts of the caves are dry.[2]
Discovery and opening to the public
There was great scientific interest in the Punkva springs as early as the 19th century. Jindřich Wankel tried to make his way upstream along the Punkva during low water, but a flooded passage, a siphon, prevented him from doing so.[1] His grandson Karel Absolon continued his research with a working group. Between 1909 and 1914 they discovered the dry part of the caves. In January 1914, Pustý žleb was thus connected to the Macocha Abyss.[1]
In 1920, a drilling team led by Lieutenant Sláma, after blasting through ceilings, made its way upstream along the Punkva spring into the first unknown spaces. Passages through which the Punkva flowed were discovered, as well as dry chambers decorated with stalactites and stalagmites. Part of the caves was soon opened to the public. The largest chamber was named the Masaryk Dome after it was visited by the first president of Czechoslovakia.[1] Absolon directed further work, and the biggest obstacle was the 40-metre-deep Zlý sifon. The level of the underground Punkva was lowered by driving a 400-metre-long drainage tunnel, but the water in the siphon still had to be pumped out.[1]
The water-filled section and adjoining dry spaces were explored between 1920 and 1933, and in some places discoveries continue to this day. According to the Cave Administration, the dry part was opened to the public as early as 1909, and the system has been shown in its present extent since 1933. Boat trips have been running since 1920.[2]
Parameters
All the known passages of the Punkva Caves together measure 4 km, with an elevation difference of over 187 m. The section open to the public is 1,250 m long, and a tour takes an hour. The air temperature is 7–8 °C and the relative humidity is around 99%. These figures are given by the Cave Administration of the Czech Republic on its website.[2]
The Macocha Abyss
The Macocha Abyss is the largest abyss of its type in Central Europe. It is 138.4 metres deep and measures 174 × 76 metres in plan.[3] It most likely formed when the weakened vault of an underground dome, through which the sinking river Punkva flows, collapsed. The dimensions of the abyss allow daylight to reach the entire space, which is why karst classification places it in the "light hole" category.[3] The Punkva is formed by the confluence of a number of sinking watercourses, among which the Sloupský potok and Bílá voda stand out, and it flows across the bottom of the abyss through the Upper Lake and Lower Lake.[3]
The oldest written record of a human descent into the abyss dates from 1723, when Lazar Schopper, a monk of the Minorite monastery in Brno, had himself lowered down. By 1900, about 12 further recorded descents had followed, which gradually turned into scientific expeditions.[3] The Cave Administration cites the work of M. A. Visgio from 1663 as the first written mention of the abyss, and the expedition of Karel Rudzinský from 1784, which drew the first vertical cross-section of the abyss, as the first scientific expedition.[2] The bottom of the abyss has been part of the Punkva Caves tour since 1914.[3]
The upper viewing platform was built in 1882 by the Brno section of the Austrian Tourist Club, and the Cave Administration of the Czech Republic carried out a general repair of it in June 2007. The lower platform was built in 1899. The Czech Tourist Club built a shelter near the upper platform in 1895; it was later destroyed by fire, and Chata na Macoše was built in its place.[3]
Practical information
According to the Cave Administration's website, the abyss is freely accessible year-round and free of charge from two viewing platforms, which are about 138 and 90 metres above the bottom. The platforms are reached from a paid car park about 200 metres away. Near the upper platform stands the station of a cable car to the Punkva Caves, which, according to the website, operates only on weekends during the winter months, that is from January to March, every day from April to September, and every day except Monday from October. The information centre selling tickets is open during the summer season from May to September. Current information should be verified on the Cave Administration's website.[3]