Geografie 1972, 77, 13-20
The Genesis of the Bohunice Flat on the Southern Margin of the City of Brno
The Bohunice flat is situated in altitudes from 280 to 290 m, 80 to 90 m above the Svratka River near the city of Brno in the territory of the tectonically strongly disturbed margin of the Česká vysočina (Bohemian Highlands). The flat was considered to be genetically either a remnant of the tectonically dissected peneplain or a remnant of the high terrace of the Svratka River. A detailed analysis has shown that the flat had developed on several smaller, partly tilted, fault blocks. Its surface cuts in the same level the igneous rocks of the Brno massif and the Miocene deposits. Relics of manycoloured, deep, probably tropical products of weathering kept preserved under favourable conditions on some fault blocks on the igneous rocks of the Brno massif and in the substratum of the Miocene deposits. Also the basal beds of the miocene deposits - consist of redeposited products of weathering. The prevailing part of the flat surface is formed of loess levelling and covering the unevennesses of the pre-Quaternary substratum. Their thickness is very variable ranging between 0 and 11 m. At the loess basis gravel remnants can be found in places consisting of hornstone and quartz. The relief of the flat is the result of a long and complicated polygenetic development. On the basis of the relation to a complete sequence of Quaternary deposits in the near by profile on Červený kopec Hill, the preserved remnants of the gravel mantle and the occurrence of flats in the same altitude in the surroundings territory, the author is of the opinion that the flat developed due to lateral erosion of the Svratka River, probably already during Upper Pliocene. In the course of the development in Quaternary when the Svratka River incised by 80 up to 90 m, the effects of linear erosion, periglacial destructional processes and loes sedimentation manifested themselves alternately on the flat. Owing to destructional periglacial processes the flat lost almost completely its gravel mantle, and a pattern of shallow dells developed. The loess deposition levelled the unevennesses in the flat surface and gave thus to the territory the morphographical character of a uniform, continuous, flat. The present morphographical features of the flat therefore mostly the result of the loess sedimentation.
