Háromszög Cave

The Háromszög Cave is a cave located in the Pilis Mountains within the Danube–Ipoly National Park, in Oszoly.

Description

It is situated in the outskirts of Csobánka, in the hollow of the middle rock wall of the first large rock group located east of the Oszoly Óra cliff. Starting from the Óra cliff heading east, one can reach the cave entrance after about 100–150 m, at roughly the same height as the base of the cliff on the steep mountainside. The 5 m long cave was formed by corrosion in Upper Triassic Dachstein limestone. The cross‑section of the cave’s entrance passage is characteristically triangular, which gave the cave its name.

After entering the entrance, a small passage leads to a spacious chamber that marks the end of the cave, where the formations can be observed more or less level. From the chamber, fissures that gradually narrow in several directions originate, but none are significant for further exploration. The cave can be walked in street clothing, but a lamp is also needed for thorough observation of the abundant moonmilk on the cave walls.

In 1997 the cave was called Háromszög Cave for the first time in its literature.

Research history

In the 1967 book *Pilis útikalauz* it was reported that on the southern side facing Csobánka in Oszoly, among the forest‑surrounded limestone rocks, there are several insignificant cavities.

In the 1974 book Pilis útikalauz, in the list of caves of the Pilis Mountains and the Visegrád Mountains (pages 19–20), it is mentioned that among the caves of the Pilis Mountains and the Visegrád Mountains are the Oszoly caves. According to the section describing the caves of the Pilis Mountains, there are about a dozen small caves among the Oszoly rocks rising above Csobánka. These were mapped and regularly explored by the Szpeleológia Barlangkutató Csoport. Most of these small caves are not very spectacular, but they must be mentioned because some of them provide excellent bivouac possibilities in the Oszoly rock walls regularly visited by tourists, especially rock climbers, and in their vicinity.

The 1991 guide repeats the general description of the Oszoly caves presented in the 1974 guide. The 1996 cave day tour guide repeats the description found in the 1991 guide, which generally presents the Oszoly caves. On May 23, 1997, Regős József surveyed the cave and, based on the survey, on May 24, 1997, Kraus Sándor drew a floor plan map with a cross‑section and a longitudinal section map, which were made at a scale of 1:50.

On May 23, 1997, based on József Kárpát's 1990 overview map of the Oszoly area, Sándor Kraus drew a site plan showing the geographic locations of the cavities of the Oszoly rock pillars. The plan shows the geographic position of the cave marked with the name Háromszög. In Sándor Kraus's 1997 report it is readable that the Háromszög cave, unknown before 1997, had its map made in 1997. The 1997 site plan was included in the report. The book *Magyar hegyisport és turista enciklopédia* published in 2005 mentions that in the Oszoly forest rock blocks and small cave openings alternate sporadically.