Hosszúerdő-hegyi Cave

The Hosszúerdő-hegyi rock cavity is a cave located in the Budai Landscape Protection Zone of the Danube–Ipoly National Park, in the Buda Hills.

Description

The cave is situated in the outskirts of Remeteszőlős, on Hosszúerdő Hill, in a specially protected area. The Hosszúerdő-hegyi rock cavity lies on the western side of the two former stone quarries, which are no longer worked, on the DNy side of Hosszúerdő Hill rising at the edge of Budapest-Máriaremete (Budapest District II).

A water-origin karst cave. The cave is easily accessible, and for a visit using basic caving equipment it is not necessary to obtain a permit.

Research history

Takácsné Bolner Katalin (cave science department) prepared the longitudinal section map and the cross‑section map of the Hosszúerdő-hegyi rock cavity (cave survey area 4750) in 1985. According to the map, the cave is 5.2 m long, 1.7 m high and 2.7 m deep. The map indicates the east direction. The longitudinal section map shows the location of the cross‑section within the cave. Kovács Richárd digitized the two maps drawn in 1985 in 2002.

The 2003 report of the Anubis Cave Exploration Department states that in the Buda Hills, in the outskirts of Nagykovácsi, on Hosszúerdő Hill, from the elevation point number 65-1412 to ENy, 190 m away, in the wall of an old stone quarry, from the Rácskai stone quarry to ENy, 140 m away, opens the Hosszúerdő‑hegyi rock cavity, which is a water‑filled, recharged bat cave. In January 2003, during a field walk, the association found in the undeveloped stone quarry wall on the ENy side of Hosszúerdő Hill a typically water‑formed bat cave of 1–1.5 m diameter and 5 m depth. It is possible that the cave is listed in the cave register containing the caves of the Buda Hills, but the department members could not obtain the cave’s register number. In the cave entrance, intense vapor rising due to the temperature difference was visible.

Descending into the shaft, 3 m below the entrance, a pea‑stone type aragonite thickly coats a part of the shaft’s side wall, and in places later‑formed dripstones 5–6 cm long can be observed. In the upper 50–60 cm of the loose structure forming the end point of the cave, probably collapsed rock debris from mining, many montmorillonite deposits were detected. On the wall at the shaft’s end point a fine‑structured, laminar calcite deposit was visible, which is known from the Rácskai Cave. The presence of montmorillonite and the laminar calcite deposit, as well as the intense outgassing, make it conceivable that by removing the rock debris in the cave passage the way would open to the water‑origin cave system running under Hosszúerdő Hill. The extracted fill, consisting mainly of rock debris, will be placed in the mine yard in a manner fitting the landscape. A map fragment showing the cave’s geographical location is attached to the report. The report also includes the longitudinal cross‑section map of the 5 m deep cave.

The other part of the report states that the department began exploring the cave in May 2003. The exploration work was made difficult by the fact that when the cave chamber collapsed, many stone blocks weighing 4–500 kg fell into the passage. These were broken into small pieces to be carried to the surface. At a depth of 7 m (reached by lowering the floor), they found that many (laminar) calcites in the fill they had disturbed were heavily cemented with the surrounding rock debris. The location of laminar calcites lying in the untouched fill of the side wall of the research shaft shows that calcite formation occurred among the loosely assembled collapse blocks. This observation, however, contradicts the earlier notion that the material filling the passage entered the cave after the cave opening.

Descending to a depth of 8 m, the debris in the passage began to hollow out and, after a large stone block was removed, fell into the opened passage. The area of the breakage was cleared, and then they descended into the opened passage. The cave continued as a tube‑shaped passage with a diameter of 50×70 cm, almost vertical, but at a narrow section located 1.5 m lower, an 8–10 kg stone block blocked the way. Because a walkable (crawlable) sized passage was visible between the stone and the stalagmite wall, they decided to remove the stone block. Due to the limited space in the passage they could not reach the stone while leaning forward. Therefore, in the classic way (rope tied to the leg, then descending head‑first) they tried to remove the stone. Because of the poor force‑application conditions, this method was unsuccessful. Then, hanging head‑first on the rope, they loosened the stone and lifted it out of the passage with a crowbar.

However, they achieved little with this, because after the narrow section the passage continued only 2 m vertically downward in a walkable manner, then narrowed to a 30–40 cm spring tube. The entire cross‑section of the passage’s endpoint was filled with fine, dry debris. Further exploration of the cave became hopeless without the use of deep‑mining technology. The group decided to finish the investigation of the Hosszúerdő‑hegy rock cavity. Attached to this part of the manuscript is a longitudinal section map of the cave showing it down to a depth of 10 m.

Richárd Kovács (Ariadne Cave and Shaft Exploration Association) compiled the longitudinal section map and the cross‑section map of the Hosszúerdő‑hegyi cave (cave survey area 4750, Nagykovácsi) on January 30, 2004. The cave was surveyed by Jenő Kovács (Ariadne KBE) for the preparation of the maps. According to the map the cave is 16 m long, 12.5 m deep and 2 m high. The east direction is marked on the map sheet. The longitudinal section map shows the location of the cross‑section within the cave.