Granite landforms in South Moravia (Czech Republic)

Abstract

The pre-Variscan Dyje and Brno Massifs were unmantled and deeply eroded already before the Devonian. The massifs were strongly affected by Variscan nappe tectonics, accompanied by cataclasis and mylonitisation. These processes were not favourable for the evolution of typical granite topography. On the extensive regional planation surface the only remarkable features are relics of a very thick kaoline weathering crust (80-100 m). Although tropical weathering was the primary process in formation of kaoilnes, the importance of Variscan nappe tectonics is undisputable. Granite landforms are more frequent in the Dyje Massif, probably owing to the deep level of denudation and less intense shattering. They occur on the southeastern marginal slope of the Bohemian Massif and in the deep river valleys, especially in the Dyje canyon. On the marginal slope, the most conspicuous forms are inselbergs. Some of them were buried under Miocene sediments and later partly exhumed. Tors and microforms (weathering pits, exfoliation) are rare. In the meandering Dyje canyon the granite forms are numerous and in general they are also younger. Most common are the valley-side granite tors and block fields. Microforms, e.g. tafoni and pseudolapiés, mainly occur on the south-facing slopes.