Original paper

Investigation of covered karst form development using geophysical measurements

Veress, Márton


We present the development of covered karst forms in the Bakony Mountains and those conditions which determine the formation of the various morphological types in the study. Using geophysical methods (vertical electrical sounding, multi electrode measuring), we measured the resistivity of the rock in the sample areas. If we know the values of resistivity we can establish the type of the covering and its structure, the thickness of covering sedimentary rock, and the morphology of the limestone floor at the measurement sites. By using the above mentioned data we were able to construct geoelectrical-geological cross-sections and morphological maps of the limestone floor from the research areas. By analyzing those data we established that covered karst forms developed primarily in thin covering sedimentary rock. Such places occur at the elevations of the limestone floor. These forms were created by breakdown. Major depressions developed exclusively in the covering sedimentary rock according to our measurements where the surface of the limestone floor is higher than its surroundings. Namely the density of covered karst forms is higher at these places. Therefore the sedimentary cover is transported in greater quantity into the karst. A burrow develops in the covering sedimentary rock if the sedimentary rock is thicker. The burrow causes the development of covered karst forms. The development of the covered karst forms may happen if the sediment which is above a blind burrow sinks because of breakdown or subsidence. The cause of sinking can be material transport due to suffusion. Thicker sedimentary cover may be above the side slope of the elevation, or where the top of elevation is considerably covered up. Then the older pit of the limestone floor may lose its sediment. Therefore, a covered karst form develops on the surface, which is younger than the pit of the limestone floor. By using multielectrode measurement we established continuous changing of the sedimentary cover along a cross-section. We produced a model of burrow development by using these data.