Szurdok-völgyi Sinkhole

The Szurdok-völgyi water well is one of the water-well caves located in the Szurdok in the Pilis Mountains on the edge of Pilisszentkereszt, within the Danube–Ipoly National Park. It is also described in tourist guidebooks.

Description

The cave is located in the outskirts of Pilisszentkereszt, about 150 m from the entrance of the quarry side of the Dera stream gorge, in a forest on the right side opposite the gorge’s flow direction (on a steep hillside), opening about 17 m above the valley floor. The old water-well entrance begins at the base of a rock overhang protruding from the valley sidewall with a 200×70 cm surface opening. The simplest way to find it is to start from the quarry at the lower end of the gorge and go upward. In the gorge one must pass the large rock block standing in the stream bed, then cross two wooden bridges. The second wooden bridge leads to the right side according to the flow direction, where one must climb 20 m up the steep hillside to reach the cave entrance. Above the mine‑like opening a sloping slab can be observed. Not far away, on the same side of the gorge, is the entrance to the Upper Cave of Szurdok-völgy.

The cave was formed in Triassic Dachstein limestone at a bedding plane due to infiltrating water. It is currently inactive.

In 1984 the cave was first called Szurdok-völgyi water well in the literature. It also appears in the literature as Pilisszentkereszti water well (Ézsiás 1993), Pilisszentkereszt water well (Kordos 1984), Szurdok-völgyi cave (Mezei 1967), Szurdokvölgyi cave (Dely, Mezei 1974), Szurdokvölgyi cave (Schőnviszky 1937), Szurdokvölgyi water well (Ézsiás 1993), Szurdokvölgyi water‑well‑cave (Ézsiás 1993), Szurdok-völgyi pit (Bertalan, Schőnviszky 1976) and Szurdok‑pit (Kadić 1952).

Research History

The 1932 issue of Barlangvilág states that members of the Budapest University Tourist Association’s Cave Research Department found a 19 m deep pit in the Szurdok valley near Pilisszentkereszt, which they surveyed and photographed. The pit ends with a stalactite chamber. The chamber is 15 m deeper than the current stream level. The 1932 issue of Turistaság és Alpinizmus reported that members of the BETE Cave Research Department discovered a beautiful stalactite cave at the bottom of a 25 m deep pit (pit) in the Szurdok valley near Pilisszentkereszt. Detailed investigation and surveying are in progress. The results will be reported later.

In the 1937 volume of Turisták Lapja it is stated that the Szurdokvölgy cave is at the border of Pilisszentkereszt, in the Szurdok valley. After the municipal burial ground, at the ground level of the first stone quarry, it opens about 5 m above the stream level. According to Kessler Hubert, who explored the cave, besides the 15–16 m entrance shaft there is a smaller chamber extending under the stream. The walls have quite beautiful stalactite encrustations. The floor of the cave is covered by stream sediment. The 1938 Geological Gazette mentions that cave erosion may have played little role in the formation of the Szurdok valley, although the smaller passages in the rock wall indicate otherwise. Among these, significant is the cave described by Jaskó Sándor, opening a few metres above the valley floor and 16 m deep.

The 1948 Hydrological Gazette published that with the uplift of Hosszú-hegy the karst water level dropped in Hosszú-hegy and the spring series of the Ziribári, Hosszúhegyi, Pilisszántói and Szurdokvölgy caves ceased to function. Water‑draining caves began to operate instead, for example the cave now blocked at the bottom of the Szurdok valley, which channels surface water flow into depth. Kadić Ottokár described the Szurdok sinkhole in his 1952 manuscript. According to the manuscript, at the border of Pilisszentkereszt, in the Szurdok valley, after the municipal burial ground, at the base of the first stone quarry, the sinkhole opens about 5 m above the stream level and is 15–16 m deep according to Kessler Hubert. Its bottom widens into a small chamber, its floor is covered by stream sediment, and its walls are nicely encrusted with stalactites. The cave description was written based on two publications.

In the study published in the 1953 Geographical Bulletin it is stated that the karst water level in the Pilis Mountains is well below the surface (at an altitude of 133 m above sea level). Therefore Imre Gábor Bekey and Sándor Jaskó found a cave passage in the Szurdok Valley 12 m beneath the bed of the Dera stream. The Szurdok Valley cave was discovered by Sándor Jaskó in 1932. 12 m deep sinkhole cave. It opens vertically downwards from the alluvium of the Dera stream. At its bottom Sándor Jaskó found a dry stream bed. According to Imre Gábor Bekey, Károly Jordán also entered this water‑draining cave in 1914. Thus it was already known in 1914. The most mysterious cave of unknown origin is the Szurdok Valley cave, which extends 12 m below the present valley floor. Since the rock of the Szurdok Valley throughout its length readily absorbs water along the fractures, a slow dissolution of such a valley‑underlying cave (provided that it is intermittent or the valley incision is slow) is not impossible.

The 1967 Pilis guidebook mentions that the Szurdok-völgyi cave’s entrance is on the eastern side of Hosszú-hegy, at the foot of the Pilisszentkereszti-szurdok quarry, about 5 m above the stream level. Its 16 m entrance shaft leads to a smaller chamber extending under the stream. Stalactite encrustation can be seen on the walls. The floor of the cavity is covered with stream sediment. The Pilis guidebook published in 1974, in the list of caves of the Pilis and Visegrád Mountains (pages 19–20), notes that the Szurdokvölgyi cave is among the caves of the Pilis and Visegrád Mountains. According to the section describing the caves of the Pilis Mountains, the Szurdokvölgyi cave opens on the eastern side of Hosszú-hegy, at the foot of the Pilisszentkereszti-szurdok quarry, about 5 m above the stream level. Its entrance shaft decades ago led to a smaller chamber extending under the stream. Today it is only walkable to a depth of 2 m. Stalactite encrustation can be observed on the walls, and the floor of the cavity is covered with stream sediment.