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

KARSTIFICATION

hidden rock boundary) karstification takes place. The (fragment of) block of covered surface with cones may have various size. On small blocks no surface drainage could or can develop on cover sediments. Karstification on a small block with cones The exhumation by sheet wash can take place on tilted or untilted small blocks (VERESS 1991). - If the block is untilted, the denudation of cover sediments is more or less uniform over the whole surface. The summit level of still buried cones may undergo karstic processes. Karst depressions are dolines-with-ponor of small size arranged irregularly. Fossilisation is common since the border areas and slopes of depressions are limited. (The reason for the former is the great density of depressions and for the latter is that exhuming cones hinder sheet wash.) This subtype of karstification is characteristic of the eastern portion of the Mester-Hajag (Pénzesgyőr) and the area above Judit spring. - The tilt of the block before and during exhumation cna be unidirectional (eg. on Égett Hill near Pénzesgyőr) or bidirectional (Mester-Hajag). In the former case, matter transport takes place in one, while in the latter, in two directions. While in the first case ridge-like features (Fig. 42) are exhumed (from among the cones of cone rows the unconsolidated material is hardly removed), in the second, cones are exhumed if the cones are aligned in rows (Fig. 43). Cone exhumation becomes possible since the surface of blocks do not only slope towards the cone rows but also in more or less rectangular direction. Therefore, cover sediments may be removed from the intervals of cones. Between the ridges and cone rows there are exhuming remnant terrrains buried under unconsolidated sediments. Here under cover sediments heavily truncated cones and maze-like dolines shape the basement morphology. As it has been mentioned above, karstification occurs on the summit levels of buried conesd (hidden rock boundary) or in the sides of semiexhumed cones (Figs. 44, 45). During exhumation rock boundaries are bound and acquire lower positions. Over cones karstification is shifted, new features develop and those of higher position are mostly truncated (Fig. 46). As a consequence of exhumation, an equilibrium state is produced. Another intensive exhumation stage and the accompanying rearrangement of karstification sites occurs if uplift or valley incision in the environs ensues. Exhumation may also intensify to the effect of forest clearing. The exhumed terrains with cones may be buried. In this case, the rock boundary and karstification shifts upwards in the sides of cones. The previously formed karst depressions are buried. The karstic features on the slopes of cones, destroyed, fossilised or buried by now indicate the directions of sediment transport. Thus, it is reconstructed that during exhumation karstification occured on the sides of cones in the direction of sediment transport and during accumulation the opposite side karstified. The length and direction of karst depression rows is in accordance with the length and direction of exhumed remnant terrains or cone rows. The border areas of dolines-with-ponor with or without channels are constituted by exhumed remnant terrains, which wear down during exhumation and this favours the fossilisation of karst depressions. On both the untilted and tilted blocks pseudodepressions also occur (Figs. 42, 43, 44, 45). - On terrains with cones depressions may completely replace exhumed remnant terrains (VERESS 1998). This is typical mostly of block surfaces where tilt is limited and cones are arranged irregularly (cockpit terrain), sheet wash is predominant but of insignificant extent. Those block details are particularly prone to such processes which are far from terrains of