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Abstract: The methodological assessment of the quality and the usefulness of borehole logs for karst analysis versus the use of data obtained via direct observation is the first objective of this paper. The second objective of the paper is to present — in the form of a case study — regional analysis of karst in Devonian carbonates of the Świętokrzyskie (Holy Cross) Mountains, south-central Poland. The subjects of the discussion are karst evolution stages, karst horizons, and their relationship to relief development. The analyzed examples (sites) presented herein, where the reliability of borehole data has often been verified by field observations, prove that descriptions of borehole logs can be used for karst analysis. However, borehole log data analysis is subject to many limitations and requires extensive validation. The basic condition that has to be met is the explicitness of the descriptions of karst forms in borehole logs. The number and the length of logs (“macro-records”) as well as the number and the size of karst forms (“micro-records”) are other important factors that affect log interpretation quality. Nevertheless, the principal general advantage of borehole log analysis is the representative nature of the obtained information. The formation of karst horizons independent of the lithology and the stratigraphy of the Kowala Fm in the Świętokrzyskie Mountains but controlled by external morphological factors suggests an isotropic character of this formation. Two general vertical types of karst systems are distinguished in this formation: (1) karst horizons, and (2) extensive karst development without distinct differentiation. The former could have been connected with fluvial base levels whereas the latter represents systems formed within the vadose zone. [Copyright &y& Elsevier]

Abstract: Widened discontinuities (among them crevice-type caves) are characteristic phenomena of landslides in anisotropic rock massifs forming the Flysch Carpathians. We tested the reliability of 2D electrical resistivity tomography (ERT) in the detection of well-mapped cave passages and then tried to explore new subsurface cavities in three sites of crevice-type caves in the Polish Flysch Carpathians: the Jaskinia Miecharska, Jaskinia Malinowska and Jaskinia Diabla Dziura caves; each comprising a different stage of mass-movement development and thus being a representative case study. The total of 14 ERT profiles was selected, while each of them was measured by several electrode arrays (dipole–dipole, Wenner and/or Wenner–Schlumberger). Our results show that the selection of an appropriate electrode array and spacing are crucial for the detection of subsurface cavities. Measurement using the dipole–dipole electrode array gave best results in the detection of known structures and its interpretation seems to be most reliable in the extrapolation of non-investigated areas. The application of ERT shows abundant occurrence of air-filled voids in gravitationally deformed flysch massifs and in several places its results enable comparison with open spaces detected by speleological exploration. ERT enables us to identify fractures in deformed slopes before the proper failure of these slopes affected by a landslide as well as in landslides themselves: fissure zones connected with trenches, less dense segments of colluvial ramparts and some lithological-tectonical or gravitationally induced elements of slope structures. The reliability of ERT detection of potential caves was verified by speleological exploration of a newly discovered cave at the Jaskinia Miecharska site following the ERT campaign. [ABSTRACT FROM AUTHOR]