Veress Márton: A Bakony természettudományi kutatásának eredményei 23. - Covered karst evolution... (Zirc, 2000)

KARSTIFICATION

margins. In numerous places in the continuation of cave remnants of valley sides collapse dolines follow beyond the valley margin. The only explanation to this is the exposure of underground cavities by the valley in valley sides, while beyond the valley margin (or the continuations of those in the valley sides) cave in and loose their cavity character. Collapse origin is confirmed by their arrangement and morphology similar to depressions of the Dohányos Hill (Kab Hill), formed by the caving of the ceilings of mine galleries. The origin of the solution origin of the cavities from which collapse dolines develop is evidenced by the following observations. - In the sidee walls of collapse dolines solution features are common (eg. ruins of chimneys). - Collapse dolines are of small dimensions; could have developed from cavities of some metres' length, 1-2 dm or at most 1 m depth and width and occur in great density in an area. These properties contradict an erosional origin as well as the summit position of depressions on terrains between valleys and the lack of erosional channels, even of blind valleys. - It was mentioned that collapse dolines are typical of terrains of Middle Eocene nummulitic limestone. If they were of erosional origin, some collapse dolines would extend over the neighbouring Triassic carbonate rocks. In the case of erosional origin there would be no reason why the cavities resulting in collapse doline formation should be restricted to Eocene limestone. - Their fill is a mixture of stone fragments, soil and reworked loess. Their appearance and composition also denies origin by erosion. Cave remnants Cavities formed in the zone of flowing karst water and exposed subsequently through the erosion of the enclosing rock are called cave remnants (VERESS 1980a, 1981a). Valley cave remnants are formed during valley development (Figs. 30,31). Those in summit position are exposed by frost shattering or mass movements on the summit levels (Figs. 32, 33) and those on the margins of plateaus through similar porcesses on the scarps of blocks. An example for a cave remnant in summit position is the Likas-kő of Hódos-ér and cave remnants on margins of plateaus are the caves of Magos Hill, Tönkölös Hill and Kőrisgyőr Hill. The development of cavities later exposed as cave remnants in the zone of flowing karst water is proved by features like spherical cauldrons on the cave walls (Pict. 35), which attest to mixing corrosion. (In the percolating karst water zone there is no or not much opportunity for mixing corrosion but conditions in the zone of flowing karst water are much more favourable.) In the zone of flowing karst water conditions do not only favour cave remnant development but also that of spring caves. In the mountains studied, however, caves are not of spring cave character but cave remnants as it is proved below. - The superimposed valleys in the mountains could develop during uplift, which resulted in the subsidence of the main karst water level. The regressional incision of valley floors follows the subsidence of the karst water table only belatedly. Parallel to incision, valley floors reach lower positions at a slower rate than that of uplift of blocks. In an opposite case valley floors would subside below the neighbouring surfaces (of the Little Hungarian Plain). This statement is confirmed by the present-day conditons in the mountains. The floors of superimposed valleys are in a hanging position above the main karst water level (even