Some aspects of lithological and exogenic control of sandstone morphology, the Świętokrzyskie (Holy Cross) Mts. case study, Poland

Various morphologies of cliffs built of different quartzose rocks in the Świętokrzyskie (Holy Cross) Mts. (upland region, central Poland) - from Cambrian quartzites and Devonian quartzitic sandstones to Triassic and Jurassic porous sandstones - were described in order to examine the constraints of their lithological and spatial occurrence. The quantitative study of the occurrence of these morphologies on cliffs makes it possible to distinguish two principal groups of morphologies: angular relief produced by rock splitting (crumbling), typical of quartzites indurated in silica and of open porosity less than 1.5%, and morphologies developed due to granular disintegration and exfoliation of sandstones of open porosity higher than 1.5%. Among the relief types of this second group, morphology reflecting sedimentary and diagenetic structures as well as smooth surfaces are the most common and are referred to sandstones of a wide range of porosity, whereas honeycombs and surfaces suffering fast granular decay and scaling are characteristic of rocks of specific porosity (respectively: 5-8% and 3.5-8%). The occurrence of honeycombs on rock surfaces is also conditioned by exogenic factors: sun, wind and rain, since this morphology tends to occur on cliffs with aspects ranging from south-east, through south, to west-north-west.