A MODEL OF THE DEVELOPMENT OF GEOMORPHOLO GICAL SURFACES REPEATEDLY RESHAPED BY EROSION AND ACCUMULATION PROCESSES

This model claims that planated surfaces once produced by some erosion al processes (peneplanation, pedimentation, pediplanation, etchplanati on, etc.) were reshaped in later geological periods by repeated erosio nal or accumulational processes, with the morphostructure also being r epeatedly affected by tectonic uplift or subsidence. According to this model, late Mesozoic tropical etchplanation with palaeokarst formatio n did not continue during the Tertiary in the Transdanubian Mountains of Hungary. Most of the mountain range was buried - as a consequence o f multiple tectonic subsidences, with deposits thickness varying and a t different intervals under sediments. This burial was followed by two or three episodes (Palaeogene, Neogene and Quaternary) of complete or partial exhumation. During repeated processes of burial and exhumatio n the Cretaceous tropical etchplain was affected by further erosion or accumulation through non-tropical processes (such as peripedimentatio n, marine terrace formation, alluvial fan building, and others). In th e horst series of the Transdanubian Mountains, divided by graben-like basins, the position and geomorphic evolution of the geomorphological surfaces allows for five main elements to be identified: 1. (semi)exhu med planated horsts in summit position, 2. buried planated horsts in u plifted position, 3. planated horsts in threshold position, buried or exhumed and reshaped, mostly pedimented, 4. buried etchplain in basin positionm, 5. peripediments, rock pediments, locally buried under depo sits. The ''alternating of erosion and accumulation-model'' of geomorp hic evolution does not only apply to the Hungarian mountains of medium height, but also to numerous other geomorphological regions, e.g. the Alpine-Carpathian-Dinaric Ranges, several old mountains ranges and ma ssifs of Europe and other continents.