Öreg-kő No. 1. Pothole

The Öreg-kő No. 1 pothole is one of the specially protected caves of Hungary. It is located in the Gerecse Landscape Protection Area of the Danube–Ipoly National Park. It is one of the six specially protected caves of the Gerecse Mountains. For a long time it was believed that this cave was the deepest cave of the Gerecse Mountains.

Description

The Öreg-kő is on the rocky and steep K side, east of the Jankovich cave. It opens at the base of a rock wall. It can be most easily approached from the resting place below Öreg-kő. A stair branch heading east leads up to it from the resting place. The entrance is 1 meter high and narrow, about 60 cm wide, and is locked with a metal grating door.

It formed in Upper Triassic Dachstein limestone along a fracture line as a result of the dissolution of warm karst water flowing along it. Its entrance shaft, the Great Shaft, leads to a steeply sloping chamber, the Great Chamber. Well‑developed spherical niches and spherical stalactites can be observed on its walls. The Barite Niche is located below the Great Shaft. This niche formed earlier than the other cavities of the pothole. In the niche there are barite crystals with a habit length of 4–5 cm. In the early 1950s they were also 10–12 cm long. Large areas are covered by pea‑stone and cauliflower‑shaped aragonite, as well as calcite deposits. In some places a microcrystalline gypsum crust has settled on previously precipitated deposits. A boxwork structure is also visible in it. The curved crystals, gypsum flowers of the Great Chamber and the 10–12 cm habit crystals of the niche have disappeared. Due to the presence of hydrothermal mineral deposits and hydrothermal forms, the thermal water origin can be best demonstrated here among the Gerecse caves.

The height of the part called the Great Hall is usually 2–5 m, its width 6–8 m and 25 m long. One important Hungarian habitat of bats. In the mid‑1900s a colony probably consisting of several hundred individuals lived in the pothole. Currently 30–50 bats use it as a winter roost each year. Mostly the small long‑eared bats and the common bats spend their winter resting period here. In Gerecse a few individuals of the already rare round‑winged long‑eared bat population have also been observed there repeatedly. Apart from the roosts in Pisznice, the species’ individuals have been observed only here. The bats’ permanent winter roost and occasional summer roost. In the summer and autumn months the carbon‑dioxide content of its air increases. This value often exceeds 5 %. Visiting is possible with the permission of the Danube–Ipoly National Park Directorate, using electric lamps and rope‑technical equipment, but a visitation ban is in effect from 1 October to 30 April to ensure the tranquility of the bats living there.

In 1984 the cave was first called Öreg-kő No. 1 pothole in its literature. The cave appears in its literature as I. sz. aknabarlang (Láng 1956), I. sz. zsomboly (Boda 1965), Bajóti 1. zsomboly (Kordos 1984), Bajóti I. zsomboly (Bertalan 1976), Bajóti Öreg-kői-zsomboly I. (Bertalan, Schőnviszky 1973–1974), Feneketlen-barlang (Benedek 1966), Feneketlen-lik (Székely 1994), Feneketlen lik (Bertalan 1976), Öregkői I. sz. aknabarlang (Leél-Őssy 1954), Öreg-kői 1.sz. zsomboly (Juhász 1990), Öregkői 1. sz. zsomboly (Maróthy 1988), Öregkői I. sz. zsomboly (Jakucs, Kessler 1962), Öregkői I. zsomboly (Vigh 1937), Öregkői 1.zsomboly (Bertalan 1976), Öreg-kői 2. sz. zsomboly (Juhász 2003), Öreg-kői 2.sz. zsomboly (Juhász 2007), Öregkői Nagyzsomboly (Bertalan 1976), Öreg-kő pothole No. 1 (Takácsné, Eszterhás, Juhász, Kraus 1989), Öreg-kő pothole no. 1 (Takácsné, Eszterhás, Juhász, Kraus 1989) and Shaft No. 1 of the Öreg-kő (Topál 1989).

Research history

First Karl Jordán tried to explore it at the beginning of the 1900s. He managed to get halfway into the cave, because his candle went out several times on the way despite the lack of noticeable air movement. Because of this phenomenon he quickly returned to the surface. In his 1913 study, Imre Gábor Bekey reported that after a rope‑secured 10 m stretch there was still a shaft that could not be traversed even with a 40 m rope‑climbing device. According to him, Karl Jordán’s venture was hindered by the air quality, the high carbon‑dioxide content. Imre Gábor Bekey let a candle down more than 30 m deep and after pulling it back the candle was still burning. He also wrote about the presence of bats. According to Márton Juhász, at the beginning of the 1920s Hubert Kessler also failed to reach the endpoint and the cause of his failure was the great depth and the high carbon‑dioxide content of the air.

In 1927, using a rope‑bound ladder, a few participants of the Hungarian‑German speleology meeting managed to reach the bottom. At that time Helmuth Cramer also entered it and, together with co‑authors, wrote a study that was published in 1931, which described its formations and genetics in detail. According to the current state of science, his opinion on the cave’s developmental history is not correct. Helmuth Cramer considered it a cave formed by waters seeping in from the surface, but among the Gerecse caves, phenomena caused by sulphuric activity were first observed here. According to the study published in the 1931 issue of Turisták Lapja, the bailiff of Bajót asked the Speleology Section of the Hungarian Geological Society to investigate the two pits opening on the D‑slope of the Öreg‑kő ridge. Imre Gábor Bekey then, together with Károly Jordán and Pál Scholtz Kornél, visited this known place, but they did not reach the bottom of the pits because Károly Jordán said that, in his opinion, the two pits were filled with carbonic acid. Their lamp indeed went out. However, the pits could not have been filled with poisonous gases and the lamp was probably extinguished by a draft, because shortly afterwards two brave young men, without rope equipment, reached the bottom of the two pits, where they found many guano.