Cave Levels in the Dachstein Massif (Eastern Alps)

This paper investigates the vertical distribution of horizontal and subhorizontal cave passages in the Dachstein Massif of Austria. Cave passages that are confined to vertical ranges, so-called cave levels, can be correlated with former valley floors and thus reflect tectonically and climatically stable periods. Previous studies analyzed significant karst Massifs (or parts of them) in the Northern Calcareous Alps but have excluded the Dachstein massif so far. The Dachstein is the second largest massif in the area, contains many extensive caves, and plays a key role in reconstruction of landscape evolution (“Dachstein surface”). In contrast to some previous works, we aimed to analyze only passages that formed (or are forming) under phreatic or epiphreatic conditions (i.e. permanently or episodically water-filled). This genetic classification is based on field observations, cave maps, 3D survey shots and descriptions. For this study, 789 caves with a total length of 279 km were considered, but data were only available for 599 caves (276 km). Only 25% of all caves in the Dachstein Massif are at least partly of (epi)phreatic origin, but the total length of phreatic passages is 204 km. Altitudes of the phreatic sections of each cave were grouped in 25-m increments and plotted according to their phreatic passage length. It turned out that there are five vertical accumulations of caves in the Dachstein Massif. Despite some previous studies that also considered morphological, hydrological, and sedimentological characteristics, our correlation with the “classical” supra-regional cave levels in other karst massifs was based only on elevation. The following elevations for the cave levels were determined: Spring Cave Level: 475-775 m a.s.l., Berger Cave Level: 825-1075 m, Giant Cave Level (with the highest peak): 1125-1550 m, Ruin Cave Level: 1600-2050 m, and a formerly unknown level at 2525-2750 m, for which we propose the name Voodoo Cave Level. According to this study the two longest cave systems, the Hirlatzhöhle (114 km long and 1560 m deep) and the Dachstein-Mammuthöhle (68 km, 1207 m) are most relevant for the result. The local vertical distribution of caves within the Dachstein was compared with the regional northward tilt of cave levels in the Northern Calcareous Alps, however the heterogeneous distribution of the known cave obscures local effects in the Dachstein Massif.