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

METHODS

Drawing profiles - Profiles were drawn from topographic maps. The profile of the underlying limestone sequence was constructed along a section of the Öregfolyás Valley using data from outcrops and a well deepened into cover sediments on the valley floor. It was found that the valley formed in cover sediments filling the cone series. In its side an incipient exhumation of the cones is observed (from under the Csatka Gravel Formation). Consequently, the valley sides are composed of the slopes of exhuming cones. The caves of the Ördög-árok are represented in the longitudinal section of the channel. The profile shows a scattering of caves and this excludes their origin as spring caves. It is also clear that scattering increases from the upper end of the valley towards the lower one. It can be only explained if the earlier developed lower valley sections are assumed to have even exposed cavities at lower altitudes. Boreholes More than a hundred boreholes were deepened by motor-driven spiral borer, often in some metres' intervals, into the cover sediments in the Mester-Hajag area, around karst object G-6/b and on the karst terrain along the Homód-árok. The interpretation of information from boreholes and the maps of underlying karst sediment surface provided the following results: - In some boreholes (eg. in the environs of karst object G-6/b) the water table was reached. This indicates the lasting presence of water in cover sediments and allows the conclusion that even in periods without precipitation dissolution can take place in the karst chimneys of covered karsts (hidden activity). - Karstic depressions are located where cover sediments are thinner (hidden rock boundary). - Under cover sediments, over buried cones filled fossil surface karst features occur in higher positions than of now active unfilled karstic depressions. This is an indication of the shifting of sites of karstificatioa - The composition of cover sediments on presently karstifying terrains points to karst processes active prior to the development of conical features but preceeding present-day karstification. - The shifting of the sites of karstification and lasting karstification over the uneven surface of underlying rocks results in the removal of cover sediments in depth. The process produces spots of cover sediments where interior drainage develops (depressions). - The carbonic sequences recovered from cover sediments provide further data for fossilization. Exploration pits With the assistance of the Cholnoky Jenő Karst and Cave Exploration Association and students of geography, exploration pits were dug in karstic depressions (Gy-9, Hu-1, Hu-7, G-6/b, G-10, G-12, G-14); in several sites of Mester-Hajag, in three „wallows" of the karst area along the Homód-árok and in some collapse dolines of Dörgő HilL Exposing the sediments filling karstic depressions, the sedimentation accompanying fossilization, the way of deposition (eg. the dips of strata decrease towards the top of the sequence, there are lenses of intercalations locally), sedimentation structure (eg. laminite),