Przegląd Geograficzny (2018) vol. 90, iss. 3
The origin of ‘rock cities’ on sandstone plateaus
Przegląd Geograficzny (2018) vol. 90, iss. 3, pp. 379-402 | 
Full text
doi: https://doi.org/10.7163/PrzG.2018.3.1
Abstract
‘Rock cities’ – a geomorphological term widely used in Czechia, but hardly formalised elsewhere – are spectacular rock-cut landscapes consisting of closelyspaced residual rock blocks separated by narrow intersecting corridors, imparting an overall visual resemblance to an urban landscape. The heights of the rock blocks in question – as compared with the floors of the corridors and passages – may reach many tens of metres. These landforms are known in a wide range of lithologies, including limestones, dolomites, conglomerates, tuffs and granites; but they are particularly well developed in regularly jointed sandstones which support a plateau and cuesta morphology. Typical geomorphic settings of rock cities are marginal parts of plateaus, backslopes of cuesta ridges and top parts of residual hills (mesas). Examples of sandstone rock cities from south-west Poland include the mesa of Szczeliniec Wielki and the plateau of Skalniak (the socalled Błędne Skały rock labyrinth, Dziedziniec), whereas they are even better represented in the adjacent part of Czechia (at the Adršpach and Teplice ‘Rock Cities’ and Ostaš). Further rock cities can be found in northern Czechia, within an extensive tableland built of Upper Cretaceous sedimentary formations, chiefly sandstones, and then in Saxony, Germany. The origin and evolution of the ‘rock cities’ are primarily controlled by structure, i.e. the pattern of discontinuities within the rock mass. These, preferentially eroded due to mechanical weakness, turn into ‘streets’, and into ‘squares’ at their intersections. However, the rock mass itself has to be strong enough to support steep to vertical rock faces, and in sandstones the strength is the combined result of wide joint spacing in certain sandstone variants and the presence of surface crusts of chemical and biochemical origin. The latter prevent steady grain-by-grain disintegration. A wide range of processes are thus involved in the formation of sandstone ‘rock cities’, including surface and subsurface weathering (including silica dissolution), mass movements of different types, underground erosion (piping), and subordinately fluvial erosion and aeolian abrasion. Despite these being spectacular landscapes, very few models of long-term evolution of ‘rock city’ and ruiniform relief have been presented in the literature, and it is anyway unlikely that any one scenario would apply to all situations. Rather, ‘rock cities’ are most probably examples of geomorphological convergence.
Keywords: geomorfologia strukturalna, rzeźba piaskowcowa, erozja podpowierzchniowa, ruchy masowe
[filip.duszynski@uwr.edu.pl], Uniwersytet Wrocławski, Instytut Geografii i Rozwoju Regionalnego
[piotr.migon@uwr.edu.pl], Institute of Geography and Regional Development University of Wrocław Pl. Uniwersytecki 1, 50-137 Wrocław: Poland
Citation
APA: Duszyński, F., & Migoń, P. (2018). Geneza skalnych miast na płaskowyżach piaskowcowych. Przegląd Geograficzny, 90(3), 379-402. https://doi.org/10.7163/PrzG.2018.3.1
MLA: Duszyński, Filip and Migoń, Piotr. "Geneza skalnych miast na płaskowyżach piaskowcowych". Przegląd Geograficzny, vol. 90, no. 3, 2018, pp. 379-402. https://doi.org/10.7163/PrzG.2018.3.1
Chicago: Duszyński, Filip and Migoń, Piotr. "Geneza skalnych miast na płaskowyżach piaskowcowych". Przegląd Geograficzny 90, no. 3 (2018): 379-402. https://doi.org/10.7163/PrzG.2018.3.1
Harvard: Duszyński, F., & Migoń, P. 2018. "Geneza skalnych miast na płaskowyżach piaskowcowych". Przegląd Geograficzny, vol. 90, no. 3, pp. 379-402. https://doi.org/10.7163/PrzG.2018.3.1