Geologickývýzkum na soutoku Dyje, Kyjovky a Moravy.

This article presents the results gathered during geological mapping of the northern part of the Vienna Basin. During this investigation the fluvial terracess of the rivers Morava and Dyje were found to belong to the Middle Pleistocene period with their bases at relative altitudes of 15-22 and 0-2 above the floodplain surface (the so-called the main terrace step). The thickness of the sediments ranges between 1 and 11 m. The upper parts of the sedimentary sequence are often affected by periglacial processes and covered by aeolian sand from the Last Glacial period. The results of lithological analysis show the dominance of quartz and crystalline rocks, while amphibole and garnet were found to be most abundant in heavy mineral fraction. The remnants of boundaries of glacial fauna and trees, and radiocarbon dating indicate Pleniglacial age (22 400 ± 2 500 years BP, 35 514-19 836 cal years BC, and 16 170 ± 480 cal years BP, 18 811-16 576 cal years BC). The fine-grained fluvial and aeolian deposits of the floodplain were affected by resedimentation during the Last Glacial period and the early Holocene, which resulted in the development of sandy elevations 2 to 6 m, maximum 8 m high. They are called "hrúdy" being possibly of polygenetic origin, including aeolian transport, basing on the study of microtextures on the surface of quartz grains. The hilly landscape of the area was colonized with short breaks since Mesolithic Period up to the Great Moravia Period. The "hrúdy" structures are believed to have undergone a multiphase development that is supported by findings of mesolithic artifacts, and by the occurrence of buried chernozem inside of the sandy infill ("Barvínkův hrúd" southeast of the Břeclav-Pohansko hunting lodge). Many paleochannels with organic substance were identified in the Holocene muddy sandy floodplain. Palynological data on humolits and paleochannels indicate the Holocene sedimentation (Younger subatlantic period). Humolites contain mainly pollen grains from the bottomland forest (Quercus, Tilia, Fraxinus), and palynomorf synanthropic plants, which are typical of the colonization period. Furthermore, the pine (Pinus), and occasionally hornbeam (Carpinus), which grew in dry places ("hrúdy") are abundant in the area studied. [ABSTRACT FROM AUTHOR]