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

RESEARCH HISTORY

forming entire streams which often disappear again under rocks." He regards the Tés Plateau a karst area but emphasises the peculiar features of the karst („in fertility they are very different from the karst on the Istrian Peninsula"). Researchers engaged in the study of the Bakony karst describe the following karst features. (In author's opinion most of them use the terms denoting morphological types in other areas, that is the reason why the essential points of karstification in the study area could not be grasped completely.) The distribution of dolomite with the corresponding features is remarkable in the mountains. Under temperate climate, however, dolomite weathering differs from limestone weathering and the resulting features are also different. Dolomite weathering has been studied by JAKUCS (1971 a,b, 1980,1994), who claims that, affected by cold water, due to the dissolution of calcite, dolomite disintegrates into fine products (pulverised - JAKUCS 1971a,b, 1994). On the dolomite surfaces of the Northern Bakony the present-day erosion of existing landforms (dry valleys and conical hillocks) takes place through mechanical weathering. Karren are mentioned by several researchers (LÁNG 1958; LEÉL-ŐSSY 1987; HEVESI 1991b) but described only superficially. This is not surprising as karren in the mountains are of small size and of less marked type, subcutanous karren (mostly root karren). A comprehensive description of karren is provided by LÁNG (1958) from the W margin of the FeketeHajag (Középső-Hajag). In his opinion karren form on outcropping strata and karren formation and mechanical weathering combine to cause the parallel retreat of the surface leading to a stepped escarpment. The depressions of the covered karst of the mountains are described as ponors or dolines by various researchers. GERGELY (1938) identifies ponors ponors and dolines from various parts of the mountains (Tés Plateau, the area between Zirc and Csesznek). Loess karst phenomena are also mentioned from the area of Zirc and Porva. (Here he may have misinterpreted covered karst features.) He recognises fossilised covered karst features (Kőris Hill, Tés Plateau) and uses popular names for them: the smaller is called by locals „kálistó", the larger „förtés". RÉVÉSZ (1947) provides a good description of covered karst on the Tés Plateau and around Hárskút. In his opinion the karst features of the Tés Plateau (38 ponors are mentioned) are composite landforms: the upprt parts are bell-shaped (doline), while the lower are funnel-shaped (ponor). The development of the covered karst feartures derives from the collapse of the cavern in place of the funnel-shaped part. Forty depressions are mentioned in the Hárskút area and the subsequent subsidence of cover deposits is emphasised here. He claims that both dolines and ponors occur in the mountains. He describes that a „kálistó" is only partially a natural festure. The depression itself is of natural origin but premanent ponds can only exist in them if impounded artificially. He also deals with sedimentation associated with activity: around the flat funnel of 3-4 m diameter of the Bükkös-árok on Tés Plateau 30-40 cm deep accumulations are observed in a 30 m circle. The transitional nature of covered karst features was recognised by LÁNG (1948), who writes about dolines being transformed into ponors. He mentions the overflow of water from dolines conducted further by a „surface water-course" (correctly: valley). In his opinion there are few true ponors in the Transdanubian Mountains, he outlines the morphological and functional characteristics of covered karst depressions in the Northern Bakony. Abandoning the above karst moprhological typology, he differentiates between ponors (on the Tés Plateau) and dolines (around Pápavár) in the mountains (LÁNG 1958). No further details, however, are supplied on this type of karst depression.