Nóra Hole

The Nóra-hole is a cave located in the Aggtelek National Park. The cave, together with the other caves of the Aggtelek Karst and the Slovak Karst, is part of the World Heritage. Of the sinkholes of the Lower Mountain, this sinkhole is situated the farthest west.

Description

It opens on the western part of the plateau of the Lower Mountain, in a highly protected area, in a forest, 169 ° from the boundary stone No. XII.40, about 60 metres away, on the north‑western edge of the ridge, near the Favágó sinkhole. It is not far from the entrance of the National Blue Trail marked with a blue stripe, which on this section is a dirt road, to the north. Because of the depot excavated from it, which is visible from a distance, it is easy to find in the rare forest, otherwise it would be difficult to stumble upon. The entrance of the unsealed cave is broken, circular, sloping and 1.5 × 1.5 metres.

It formed in middle Triassic and upper Triassic Wetterstein limestone. Its horizontal extent is 6 metres. Its shape is simple. The typical cross‑section type is the circular section. In fact, along its whole length it is a broken, practically only the main‑layer limestone. The sloping passage follows the main layer that slopes at 45°. Its floor consists of compact clay. The filling has been removed from under the main layer. Dissolved surfaces dominate its speleothems, which developed mainly near the end points. Inverted stalactite formations have formed with small surfaces. Bats also use it willingly. The cave can be visited with basic caving equipment, heavy climbing and a permit. Use of a hand‑rope is recommended for the passage, because the sinkhole is slippery and steep.

The cave also appears in literature under the names Nora‑hole (Ctirad Piskač et al 2017) and Nora hole (Luděk and col. 2011).

Research history

The caves of the Aggtelek Karst and the Slovak Karst were declared a World Heritage site in 1995 and therefore this cave is also part of the World Heritage, although it was discovered later. It was uncovered by expanding a seemingly insignificant rock outcrop. On 18 July 2006 the Nóra‑hole was surveyed by Miroslav Hynšt, who then prepared the cave’s plan map and longitudinal section map based on the survey. In 2010 the Speleological Club ZO 1‑11 Barrandien, i.e. the ZO 1‑11 Barrandien Cave Research Group, inspected the cave’s condition and found that it had not changed compared to previous years.

In 2011 the group members tried to increase the length of the cave by digging, but this was not successful. At that time the cave was measured to be about 8 m deep. In their 2011 group report they published the maps of the cave made in 2006. According to the cave inventory sheet filled out in 2016, the thoroughly surveyed chamber is 12 m long, 8 m vertical extent, 8 m deep, zero metres high and has a horizontal extent of 6 m. The cave was formed along a tectonic fault line by the action of leaking water. The Nóra hole was discovered in 2010 by the ZO 1‑11 Barrandien Cave Research Group.

In 2017 Ctirad Piskač and Robert Kosáček drew the cave longitudinal section map, floor plan map and three cross‑section maps. The longitudinal section map shows the location of the three cross‑sections in the cave. For the preparation of the maps the cave was surveyed by Ctirad Piskač, Robert Kosáček, Mojmír Záviška and A. Záviška in 2013, 2016 and 2017.

In the book about the karst phenomena of Alsó-hegy published in 2019 it is written that the Nóra-hole is of unknown length and 27 m deep. The cave identification numbers are: in Slovakia 232, in Hungary 5452/96. The book published the cave maps made in 2017. The cave was surveyed in 2013, 2016 and 2017 by Ctirad Piskač, A. Záviška, Mojmír Záviška and Robert Kosáček. In 2017 Ctirad Piskač and Robert Kosáček drew the cave maps based on the survey. The maps were digitized in 2017 by Luděk Vlk. A colour photograph showing the cave research was published in the book. A detailed map of Alsó-hegy was attached to the publication. The map was made by Luděk Vlk, Mojmír Záviška, Ctirad Piskač, Jiřina Novotná, Miloš Novotný and Martin Mandel. On the map, where caves and sinkholes are marked with black dots, the geographical location of the Nóra-hole (5452/96, 232) can be seen.