Zsó Cave

Zsó Cave is one of the caves located in Oszoly in the Pilis Mountains within the Danube–Ipoly National Park. It is presented in tourist guidebooks and its entrance has long been known.

Description

It is situated in the outskirts of Csobánka, on the Margit ridge. Three metres east of the Oszoly Odúsor, at the base of a rock wall, under the Little Overhang, there is a natural entrance facing west. The cave was formed in Upper Triassic compact white thick-bedded Dachstein limestone, measuring 12 metres in length and 2.5 metres in height. One metre from the entrance it continues in a very narrow crawlway into an inactive spring cave. The cave’s fissures are filled with calcite and its floor is rocky and humus-rich. Basic caving equipment is recommended for exploration. The use of knee protection is advised.

In 1971 the cave was first called Zsó Cave in the literature. In the literature it also appears under the names Oszoly‑foxhole (Kraus 1997), Oszoly‑foxhole (Kordos 1981) and Zsó Cave (Kordos 1971).

Research History

The cave entrance has long been known. In the 1967 book *Pilis Guidebook* it was mentioned that on the western side facing Oszoly Csobánka, among the forest‑surrounded limestone rocks, several insignificant cavities can be found. The entrance was probably cleared in 1968 by the Red Meteor speleologists and rock climbers. In 1969 László Kordos surveyed it with fixed points and a mining compass, and in that year, based on the survey, Kordos László drew and edited its floor plan map and an expanded longitudinal section map, which were made at a scale of 1:100. According to the survey it is 12 metres long and 2.5 metres deep. According to a publication in the 1969 Karst and Cave Research Bulletin, in August 1969 the Speleology Cave Research Group placed fixed points in Oszoly and in eight smaller and larger cavities on the Oszoly side during a camp organized in Kevélyek.

On 22 February 1970, 22 March 1970 and 26 April 1970, László Kordos and P. Welker performed climatological measurements on the surface and in the cave with an Ansmann-type aspirating psychrometer. The 1970 report of the Speleology Cave Research Group contains a detailed description of the cave and its research history. The report states that the cave begins with a very low, 1.2 metre wide crawling passage, then the end rises slightly, where one can sit. It is probably a phreatic origin collapse cave, whose end shows a clogged stalactite flow. Completely dry, sometimes water beads on the walls. A caving suit and lamp are recommended for exploring. About three metres north of the cave is the Odúsor. The report’s appendix includes the 1969 maps.

In the book *Pilis Travel Guide* published in 1974, in the list of caves of the Pilis Mountains and the Visegrád Mountains (pages 19–20), it is mentioned that the caves of the Oszoly are located between the caves of the Pilis and Visegrád Mountains. According to the section describing the caves of the Pilis Mountains, there are a dozen small caves among the rocks of the Oszoly that rise above the Csobánka. These were mapped and regularly explored by the Speleology Cave Research Group. Most of these small caves are not very spectacular, but they should be mentioned because some of them provide excellent bivouac possibilities in the walls of the Oszoly cliffs, which are regularly visited by tourists, especially climbers. A 12‑metre long cavity, starting 3 m from the Odúsor with a 1 m wide flat passage under the Little Overhang and widening slightly towards the end, was excavated by the Red Meteor cavers.

In the 1975 MKBT Report the 1970 report's section concerning the cave was published together with the maps attached to the report. The publication contains a site drawing on which the geographic locations of the Csúcs Hill and the Oszoly caves can be seen. The drawing shows the geographic location of Zsó Cave. In the manuscript written by Bertalan Károly and completed in 1976 it is readable that Zsó Cave (temporary name) is located in the Pilis Mountains, in the Kevély group, at Pomáz. At the steep drop of Oszoly, under the Small Turn, there is a 1.2 m wide and very flat entrance. The cave is 12 m long and 2.5 m deep. The cave passage is probably of karst origin. The part of the manuscript concerning the cave was written based on one literary work.

In the 1981 first–second semester issue of Karst and Cave it was made public that the Oszolyi‑foxhole has the cave‑cadastral number 4820/17. In the 1984 book *Caves of Hungary*, which presented a national cave list, the cave appears among the Pilis Mountains caves under the name Oszolyi‑foxhole with the variant name Zsó Cave. Associated with the list, the geographic location of the cave is shown on a 1:500 000 scale map presenting the geographic locations of the Dunazug Mountains caves. In 1990 József Kárpát drew an overview map on which the geographic locations of the Oszolyi rock‑climbing school caves can be observed. This map shows the geographic location of Zsó Cave.

In the manuscript prepared by József Kárpát in 1990 it is written that the entrance of Zsó Cave (Csobánka) is 20 m D from the Delago road, at the foot of the wall of the Oszoly climbing school, at the D‑end of the climbing school. The entrance, 1.3 m wide and 0.6 m high, is located 5 m D from the rock‑climbing path called Odúsor. The cave, 12 m long and 3 m deep, is of a type that indicates it was once a spring cave, which is now inactive. Its entrance narrows to a very flat crawlway after 1 m. Pebbles, fossil stalactite encrustations and dissolution forms can be observed in the cave. Humus and stone rubble fill it. There are no signs of vandalism. It is inconvenient to walk through because it is narrow. The manuscript includes the map of the Oszoly rock‑climbing school drawn by József Kárpát in 1990. In the compilation written by József Kárpát in 1991 it is mentioned that Zsó Cave (Csobánka) is 12 m long and 3 m deep. The guidebook published in 1991 repeats the cave description from the 1974 guidebook and the general description of the Oszoly caves.