Ferenc-hegyi Cave

Ferenc-hegyi Cave is the seventh longest cave in Hungary. It is of thermal water origin like the other Rose Hill caves. In 1982 it was declared one of Hungary's specially protected caves.

Description

The cave opens in Budapest's 2nd district, on Ferenc Hill, which belongs to the Hármashatár Hill group. The cave's current artificial entrance is located on the east side of Ferenchegyi Road, at the wooded and bushy area at the Őzgida Street junction, and is closed. Its old exploratory entrance, which was in front of house number 63 Törökvész Road, was concreted over for cave and life safety reasons.

The most convoluted passage, most labyrinthine Budapest cave. It does not belong to the caves requiring high technical preparation, but is notable for its narrow, fissure-like passages. Despite Ferenc-hegyi Cave being one of the most significant caves in our country, its scientific study has been minimal. Its average ambient temperature is 9.9 °C, a value measured by Imre Loksa during a series of investigations in 1958. The cave's climatic conditions primarily reflect the connection between the cave and the surface, the interconnections of the fissure systems. It can be visited with permission from the Directorate of the Danube–Ipoly National Park.

In 1976 the cave was first called Ferenc-hegyi Cave in the literature. Ferenc-hegyi Cave also appears in the literature as Aragonit Cave (Bertalan 1976), Ferenc-hegy Cave (Kordos 1977), Ferenchegyi aragonit cave (Mottl 1934), Ferenchegyi aragonitbarlang (Polgárdy 1941), Ferenchegyi-barlang (Bertalan 1976) and Ferenchegyi cave (Kadić 1934). It is named after Ferenc Hill, in which it is located.

Formation

The cave developed along a narrow fissure system oriented ENy–DK and the perpendicular EK–DNy direction. Like the other large Buda caves, Ferenc-hegyi Cave formed primarily by the dissolving action of warm water along tectonic fissures in Eocene limestone and marl. Characteristic dissolution forms, shells, channels, spring tubes, spherical stalactites and spherical chambers can be observed in the cave. Perhaps of all the large Buda caves, this one contains the greatest amount of mineral matter indicating thermal water. Already at discovery, a mineralized thermal spring tube broken in two along its length was noticeable, which, as the name suggests, could have been one of the warm water emergence points. The Eocene nummulitic limestone walls and cracks are covered in many places by barite, which likely precipitated from higher‑temperature water just before the cave's enlargement.

It is interesting that József Kerekes found in the cave a conglomerate of quartz pebbles, probably derived from Pannonian sediment, which led him to place the cave’s formation in the Upper Pannonian. The pea stones, formed from younger, lower‑temperature warm water, may be composed of aragonite, as well as cauliflower‑like and plate‑like crystal aggregates; but traces of calcareous sponge, gypsum crystals, geyserite and lublinite have also been identified in it. Cave passages close to the surface approach, and even in several places reach, the overlying, less stable bryozoan marble.

Formations, sights

On the classic route of the cave tour one can walk through the following sections of the cave. Passing the entrance corridor, characteristic narrow places such as Harakir, the Slide and the Snake‑throat lead the visitor into a multitude of intersecting fissures. The main fissure runs EN‑DK direction. At the end of the second main fissure is the Omladék Hall, and at the junction of the third main fissure and the second cross fissure is the Mushroom Hall, which took its name from a huge mushroom‑shaped rock formation. Further, many passages lead to the Mine Hall, but the subsequent labyrinth is even more complex.

It is only with difficulty that one can find the way through the narrow Bocskai‑cave into the Barit corridor, named after the pepper‑yellow crystals covering the wall. Not far from here follows one of the cave’s largest chambers, the Bocskai Hall, whose walls lack spectacular decorations. From there, heading toward D, the walls are again adorned with pea stones and stone roses, but increasingly corroded rock walls become prominent, and at the end of the passage a river‑bed‑like deposit and spherical quartz pebbles can be observed.

Facing east, climbing the unstable debris field, the Upper floor is located, where there are two very interesting chambers. Their walls are completely smooth and rounded, giving the visitor the feeling as if they were inside a large hollow sphere. In the eastern part of the Upper floor, beyond the narrow passage, the cave's largest cavity follows. Its continuation leads into a steep abyss, which returns to the Lower level.

Research history

On September 26, 1933, drainage works were carried out on Törökvész Street, and during the deepening of the sewer trench a cavity was found. The discovery quickly spread. First it was inspected by pharmacist Géza Miklóssy, who then notified Ottó Kadić by telephone. He went to the site the same day, and since he saw that they had encountered an extremely difficult-to-navigate narrow cavity, at his request Hubert Kessler and the Budapest University Tourist Association speleologists uncovered it. According to the descriptions, its length at that time was about 500 m. The first goal was to prevent the entrance of the cave, which had opened during the advanced drainage works, from being built over. The next task was the detailed exploration and surveying of the cave. This difficult work was also carried out by the BETE speleologists, again under the leadership of Hubert Kessler. In the following years university researchers continued their exploratory work in the cave, whose length grew to almost three times that of the first explorations, reaching a length of 870 m.