Vecsembükk Pothole

The Vecsembükk Pothole is a cave selected as part of the World Heritage. The 236 m deep pothole is Hungary's third deepest cave. Here is located Hungary's longest continuous cave shaft, which is 83 m deep. It is the deepest and tenth longest cave of the Aggtelek Karst. It is one of Hungary's specially protected caves. It is one of the eight specially protected caves of Bódvaszilas.

Description

It is located in the Aggtelek National Park, on the Aggtelek Karst, on the Upper Mountain plateau. The cave, situated in the outskirts of Bódvaszilas, almost on the state border, is a bat cave whose entrance, 4–5 m wide and enclosed by a fence, opens at 522 m above sea level. The geographical location of its entrance is shown on tourist maps, where the cave is marked with the cave's name.

The unsealed pothole consists of large and vertical, parallel, often widening downward shafts, which are divided by narrowings or clay‑silt sections. In addition to the 83 m deep shaft No. 90, further deep shafts and chambers are found in it. The Entrance shaft is 65 m deep, the Side shaft 60 m deep, the Cold Dream 53 m deep. The New part's almost 90 m Rom shaft rises to 43 m high and descends to 46 m deep. Shaft No. 90 is the deepest continuous cave shaft in Hungary.

Formed in Triassic limestone. On the walls of the pits dripstones and stalactite clusters are common, and at the bottom of the pits palm‑tree‑shaped dripstones can be seen formed by water drops falling from great heights. The colour and shape of the dripstones are varied. The system consisting of wide pits 3–10 metres wide lies on a relatively small area of only 31 × 21 metres. The air temperature is very cold. At its coldest point, at about 70 metres depth, the air temperature is 3–4 °C. At the deep point a temperature rise of 6–7 °C can be measured, which is attributed to geothermal effect. The cave is in a stage of ageing. Access requires caving routine, use of rope‑technical equipment and permission from the Aggtelek National Park Directorate. Bats also occur there and therefore it is forbidden to visit them in their resting period, in winter.

Based on research carried out in the cave, István Sárváry and Pál Müller developed a formation theory that rejects the Kessler Hubert mechanical theory, seeing the formation of the pothole as purely corrodional in the surrounding Wetterstein limestone that makes up the rock. István Szenthe, however, identified quartz pebbles and metamorphic grains in the material surrounding the pothole that could not have originated from limestone dissolution residues, and instead concluded that a volcanic‑origin overlay formed on the surface of an earlier karst, which was later re‑exposed by the present karst processes. This is confirmed by the radiation measurement performed by Miklós Gádoros in 1974, during which the gamma activity of the clay plug sealing the deep point suggests a volcanic origin.

The pothole belongs to the Zsámány-well and the Kör-well water system in Slovakia. A large amount of water no longer enters at its entrance. There is also no active water flow inside. Once, judging by its size, a significant area water collector may have been attached to it, but currently, due to surface erosion, it has been placed on the rim of the sinkhole.

The tenth longest cave of the Aggtelek Karst, after the Baradla Cave, the Peace Cave, the Freedom Cave, the Vass Imre Cave, the Meteor Cave, the Kossuth Cave, the Danca Cave, the Szabó-pallagi-pothole and the Baradla Short-Lower Cave. It is one of the eight caves of Bódvaszilas that are specially protected, the other seven being the Almási-pothole, the Frank Cave, the 2nd water-absorbing cave on the Kopaszgally side, the Kopasz-vigasz Cave, the Meteor Cave, the Szabó-pallagi-pothole and the Széki-pothole.

The cave occurs in literature as 35 (Kósa 1992), Nagyvecsembükki-pothole (Börcsök, Elekes, Németh, Nyerges 1997), Nagyvecsembükki pothole (Bertalan 1976), Pongrác 5th pothole (Kordos 1984), Pongrác 5th pothole (Bertalan 1976), Propast na Vecsembükku (Vlk 2019), V/7 (Kósa 1964), V-24 (Kósa 1992), Vecsem-bükki-pothole (Kordos 1984), Vecsem-bükki pothole (Gonda 1982), Vecsembükki pothole (Bertalan 1976), Vecsembükki pothole hole (Nyerges 2003), Vecsembükk Shaft (Kordos 1977) and Vecsem-bükk Shaft (Takácsné, Eszterhás, Juhász, Kraus 1989).

Research History

In 1911 Viktor Jordán attempted to reach the bottom of the pothole during the lower-mountain pothole exploration expedition led by Károly Jordán, but could only descend to about 35 metres depth. Imre Gábor Bekey was also a member of the expedition. Hubert Kessler reached 91 metres on 14 April 1927 with the help of András Beliczay, István Frank and Gyula Kiss. In that year a report on the cave research written by Hubert Kessler was published. The publication included the cave length‑section map. The map was drawn by Gyula Kiss.

In 1929 Eugenio Boeganna published a work, written in Italian, which describes the Vecsembükk Pothole. The paper included the longitudinal section map and plan map of the cave prepared by Kessler Hubert, though the maps appeared in the publication with slight modifications. In the book titled *Barlangok mélyén* published in 1936, Kessler Hubert's expedition is described in detail. The publication shows the cave's longitudinal section map and plan map, which resemble the earlier maps of the cave. In the second edition of *Barlangok mélyén*, which appeared in 1942, the cave and its research are described, and the cave maps were published as in the first edition.