Karolina-árok Upper Cavity

The upper cavity of Karolina-árok is one of the caves located in the Karolina-árok in the Visegrád Mountains of the Danube–Ipoly National Park, in Pomáz. The cavity is also mentioned in tourist guidebooks.

Description

The upper cavity of Karolina-árok is situated 30 metres above, to the northwest of the lower cavity of Karolina-árok, in the gorge of the valley floor.

The cave was formed and continues to be shaped by the swirling erosion of a waterfall at a 3‑metre‑high rock stair made of tuff and agglomerate layered together. At its top there is a single compact rock mass of amphibole‑andesite about one and a half metres in diameter, which only partially covers the cavity, leaving an opening about one metre wide through which the waterfall still flows today. Thus the cavity can essentially be regarded as a through‑cave with two openings.

The mouth of the cave, one and a half metres wide and two metres high, faces roughly south. Its chamber, which widens to 2.5 metres and resembles an elliptical floor plan, is 3.3 metres long. Its height varies between 2 and 3 metres. The layers of tuff and agglomerate of varying hardness were carved by erosion at different depths, creating spectacular column‑like stalactite formations on the cave walls. At the bottom there is a larger rolled stone block surrounded by a debris pile of smaller stones.

In 1963 the cave was mentioned for the first time in literature as the upper cavity of Karolina-árok. In literature it also appears under the names Karolina árok felső álbarlangja (Ozoray 1963) and Karolina-árok felső barlangja (Eszterhás 1993).

Research history

According to the study published in 1963 in *Karszt és Barlang* by György Ozoray, there are a few insignificant‑sized but morphologically and origin‑wise interesting non‑karst cavities in Karolina-árok. The small cave formed 20 metres above the Karolina‑gully, beside a waterfall. Here, in the hard agglomerate, water cut a smooth, half‑tube‑shaped channel with a 32° slope, ending in a two‑metre waterfall. It cut through the hard floor and easily eroded the softer layers beneath. The swirling erosion carved a rounded cavity behind the waterfall.

In the layered alternating hardness tuff, stone‑carved drill holes were made. Selective blasting also sharpened the various depth cuttings. From a surface morphology point of view the cavity behind the waterfall is interesting, but on its own it does not reach the size of the stone cell. The flood pushed a 1.5 × 1.6 × 1.2 metre, most rounded rock block onto the cliff before the waterfall. It became stuck in the narrowing caused by the hard upper rock ledge. Thus, together with the cavity behind the waterfall, an almost closed stone cell is formed, the upper side cave of Karolina-árok. The pipe‑shaped channel carried the floodwater through this passage. The material of the jammed rock block differs from the surroundings; it is pink amphibole‑rich andesite.

A similarly composed, slightly longer and narrower block is also present at the bottom of the side cave, among the scree that forms the floor. The flood water forced its way through the narrowing and could not move further in the narrow passage below the waterfall. A floor plan map with three sections and a photograph showing the side cave were attached to the publication. The map was made by Tamasné Fodor and György Ozoray, and the photograph by György Ozoray. In the book *Pilis útikalauz* published in 1967 it is stated that small cavities are found at the base of the vertically descending steps of the Karolina-árok, which are filled with debris in a cave‑like manner. In the book *Pilis útikalauz* published in 1974, in the list of caves of the Pilis Mountains and the Visegrád Mountains (pages 19–20), it is mentioned that the caves of Karolina-árok lie between the caves of the Pilis Mountains and the Visegrád Mountains. In the section describing the caves of the Visegrád Mountains, the description from the 1967 guidebook is repeated.

In the manuscript titled *Hungary's Cave Gazetteer* completed in 1976 and written by Bertalan Károly, it is stated that the upper subcave of Karolina-árok is in the Pilis Mountains, in the Visegrád Mountains, at Pomáz, about 2.5 km east of Csobánka, in the right‑hand side branch of the Holdvilág-árok, 20 m higher than the entrance of the lower subcave of Karolina-árok. The cavity is 5 m long, 3 m wide and 2 m high. It is a cavity under a waterfall covered with a multi‑meter‑high rock column. The part of the manuscript concerning the subcave was written based on two literary works. In the national cave list of the book *Caves of Hungary* published in 1984, the subcave appears under the name Upper Subcave of Karolina-árok among the caves of the Szentendre–Visegrád Mountains. Associated with the list, the geographical location of the subcave is shown on a 1 : 500 000 scale map depicting the geographical positions of the caves of the Danube‑Zug Mountains.

In the regional bibliography section of the 1986 bibliography published in *Karszt és Barlang*, it appears under the name Karolina-árok Upper Cave. According to the compilation, among the writings published in *Karszt és Barlang* there is 1 that deals with the cave. In István Eszterhás's manuscript *List of Hungary's Non‑Karst Caves*, written in 1989, it is stated that the Karolina-árok Upper Cave in Pomáz, located in the Visegrád Mountains in the 4900 cave‑survey area, developed in an andesite conglomerate. The cave is 6 m long and 2.5 m high. The list mentions the 220 objects (203 caves and 17 artificial cavities) created in Hungary in non‑karst rock that became known by the end of 1989. In Hungary, 14 caves have formed in andesite conglomerate. According to the compilation, László Kordos's cave list published in 1984 includes 119 caves that originated in non‑karst rock.