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Mieczysław Klimaszewski

During the Tertiary period, karstic forms were also formed in the Silesian Upland and the Sw. Krzyż Mts. They are mainly great karstic sink holes filled with residual and alluvial deposits. Some scientists suggest that they datę from the Miocene age (in Continental facies), but the author saipposes them to be older. Nevertheless, the forms and deposits require further investigations and have to be linked with older forms, mainly with the degradation plains which they enclose.

The problem of the relation between the fluvial forms (of the valleys dissecting the Upland of Cracow and Silesia) and karstic phenona is very interesting. Accord-ing to older views, the valley forms are older than the karstic ones. Roglic (33) actually considers the process of valley erosion to be relatively rare within the karstic regions, and affirms that it developed simultaneously with karst processes. In the case of the Cracow-Silesian Upland, the first conception seems to be the morę probable one. The course of the karst process depends not only on climatic conditions, but also on geological ones — namely on the number and density of fissures. When fissures were scarce, smali amounts of water percolated underground, while, on the other hand, rivers developed normally and cut into the substratum. Only a large number of fissures madę possible the escape of water into the depths, underground drainage, and intense karst processes. The fissures were mainly formed under the influence of tectonic movements.

In the case of the Cracow Upland, S. Dżulyński states that: “The period of forma-tion of the joints within the Cracow Upland coincides with the period of orogenic movemenbs within the Carpathian geosyncline”. It may be suggested that, before the period of orogenic movements which took place mainly in Miocene, there were but few fissures in the Upland, and percolation conditions were unfavourable. On the other hand, the rivers were able to cut into the surface and to form normal valleys. It is very probable that, in the first period, i. e. after the formation of fissures, their absorption and capacity were still limited. Only after a widening of fissures by circulating and dissolving waters, and after the formation of caverns and tunnels could the large masses of waters be contained underground. The su-perficial river valleys were then transformed into wind gaps.

The origin of the caverns is closely connected with those facts. As in well known, climatic conditions favourable to the development of karst processes reigned during the Paleogene, but the Upland of Cracow was still tightened, so that conditions were not yet suitable for the formation of fissures. It is not surprising that no Miocene deposits were found in the caverns. The surface of the Cracow Upland was somewhat elevated above the sea level, and this did not favour the formation of karstic caverns. During the lower Pliocene, the climate was dry and unfavourable to the development of karstic phenomena. Thus conditions conducive to the formation of caverns existed only in the middle Pliocene, when the climate was humid (hot and wet) and during glacial periods, when the substratum was not too deeply frozen. Pleistocene was characterised by the flow of large masses of waters, as evidenced by: fluvial deposits, pot holes and corrosional escarpments that may be seen at the top of many corridors. Thus the caverns continued to develop during the Pleistocene and still do so, especially in the Tatra Mountains.

Translated by Juliusz Głodek