József-hegyi Cave

József-hegyi Cave is one of the specially protected caves of Hungary. It is located in the Buda Hills within the Danube–Ipoly National Park, in the 2nd district of Budapest. It is the 10th longest cave in Hungary. Among the Buda caves, this cave has the largest chambers.

Description

It is located under the Szemlőhegy district, in the interior of József Hill, in the Buda Hills, in the 2nd district of Budapest. Its entrance is on Józsefhegyi Street. In the vicinity there are about sixty other caves, among them the larger ones are the Pál Valley cave system and the Ferenc Hill cave. The cave can be entered through an artificial main entrance built on a closed plot on Józsefhegyi Street. One can descend a ladder into the former, now covered foundation pit.

The massive Kinizsi platform is 67 m long, 20–25 m wide and 5–12 m high. This is the world’s largest phreatic cave chamber. Its name refers to the discovering group, and the unusual platform designation indicates that this is not a conventional cave chamber. The floor of the chamber lies 60–65 m below the entrance, resembling a frozen and flowing river; after the first retreat of the warm water filling the cave, the dissolution residue covering the floor became partially calcified. Analyses indicate that this occurred about 220 000–230 000 years ago. 210 000 years ago, however, the water level rose again, and 200 000 years ago a small warm‑water spring forming a lake broke through to the surface. The warm water that again filled the cave was covered by calcite crust that enveloped the brain deposits. Gypsum still emerges on their surface today, giving these formations a distinctive sparkle. On the east side of the chamber, aragonite needles and gypsum crystals can still be seen in places. The side wall is also covered with calcite layers. Towards the narrowing western end of the chamber, on the side wall, a few‑millimetre‑thick, several‑centimetre‑diameter gypsum bubbles cover the wall.

At the entrance of the Ice‑cream Corridor we can see the cave’s largest gypsum crystal groups, about 1 m in size, hanging from the ceiling at the edge of the chamber. On the side of the corridor gypsum of calcite composition, generally pure white on gypsum stone and aragonite crystal needles, is visible.

One of the chambers was named after the ELTE geography professor who died in 1980, Sándor Láng, president of the Hungarian Karst and Cave Research Society. Here, besides the Gypsum Cemetery containing fallen large gypsum crystals, the most spectacular feature is the black‑coloured side wall from which, in places, angular pure‑white gypsum protrudes.

From the Láng Sándor Hall the best protected side passages can be reached: the Red Sea containing 15 cm gypsum snakes, the part called Temple of Nature adorned with the richest aragonite stalactites, and the part called Glass Palace leading to the deepest section of the cave, covered with calcite sheets and glass‑ball pepperstone. Because of strict protection, researchers usually do not enter these passages either.

At the Airport thick calcite crust covers the floor and the side wall. Thin gypsum membranes sparkle on this surface. The peculiarity of the Airport is the thin calcite crust that covers the fallen stalactite blocks from the ceiling and is leached by water dripping from above.

Another special sight opens from the 308 m long cave section discovered in the first week: in the Shell Branch there is the so‑called Árvalányhaj, hair‑thin gypsum fibers. Their length sometimes approaches 1 m. Árvalányhaj is very fragile, even the sound of speech makes it start to sway. In the Crystal Hall the fibers sometimes lie on the ground like cotton, elsewhere they hang down from the ceiling, or protrude from the side wall.

Its probable connection with the present‑day healing springs and with the Molnár János cave located about 15 m deeper is demonstrated by the fact that the average temperature of the József‑hegy Cave is above 13 °C, i.e. about 2 °C higher than that of other caves in the Rose Hill area.

The cave can be visited with the permission of the Danube–Ipoly National Park Directorate. In the literature the cave also appears as József‑hegy Cave (Takácsné, Eszterhás, Juhász, Kraus 1989).

Formation, petrology

Like the other Buda caves, tectonics played a significant role in the formation of the József‑hegy Cave. The cracks formed in the hill were enlarged into cave passages by warm‑water solutions. The main fissures of the József‑hegy Cave are oriented K‑N, and the cross‑fissures generally intersect them at angles of 30–40°.

The cave's lithological structure is varied. Part of its upper and middle levels formed in 36–38 million year old bryozoan marble, the main passage level is largely composed of the rock mass formed about 40 million years ago in the Szépvölgy Limestone, while most of the lower level's pits and fissures were formed in the Triassic period, dissolved in the locally very marly layers of the more than 200 million year old Mátyáshegy Limestone.

The cave's labyrinthine floor plan passage system can be divided into three main levels:

The lower level's passages formed in Triassic limestone are long tectonic fissures, large pits, which are only in a few places connected by walkable passages to the corridors formed above them in Eocene limestone. The narrow, high passages are not divided into chambers. In some parts the walls are free of formations or lightly coated with crystals, while elsewhere the cave's most crystal-rich, most valuable sections have developed.

The second main passage level includes chambers and corridors formed in 30–40 m thick Eocene limestone and in the lower, few‑metre‑thick level of the marble, comprising about 80 % of the cave's passages. On this level, multi‑metre, in places 10–15 m high corridors and 20–30 m high chambers are characteristic. The Kinizsi station also developed here. This level is rich in formations: the walls are mostly covered with aragonite crystals and pea‑stones, on which gypsum crust forms. In the formation‑free sections the passages are adorned with very beautiful dissolution forms. The floor of the corridors and chambers is covered with debris and clay fill. These mostly represent the limestone dissolution residue, but in many places there is also significant clay deposition from the upper level.