Margin of the Scandinavian glaciation in the Moravian Gate

 

Jaroslav Tyráček

Geoscience Research Reports 40, 2007 (GRR for 2006), pages 97–101
Map sheets: Hranice (25-12)

Full text (PDF, 0.4 MB)

 

Abstract

The Middle Pleistocene Scandinavian ice sheet that reached twice during Elsterian and Saalian in form of a large lobe from Poland into the Ostrava Basin left behind vast quantities of glaciofluvial sand and gravel, glaciolacustrine clay and silt and glacial till. The area of the marginal part can be subdivided into three separate sectors characterized by diverse sediments and morphology. 1. The NW belt stretches between the marginal slopes of the Paleozoic Nízký Jeseník upland and the valley of the Vražný brook. The glaciofluvial sand and gravel up to 15 m thick deposited by meltwaters flowing SW-ward parallel to the tectonic contact between the Paleozoic of the Bohemian Massif and the Neogene of the Carpathian foredeep, fill shallow depressions in the Neogene bedrock. No tills are recorded and the glacier probably stopped close to the Vražné village. Because of the distance and several intervening valleys belonging still into the Odra drainage basin neither the glacier nor the meltwaters crossed the main European water divide between the Baltic and Black seas at the altitude of the "70 mfluvioglacial terrace" - sector 1 (Section 1-1', Fig. 2). 2. The glaciofluvial sand and gravel topped by till in total thickness of 15-25 m form the Hynčice-Hrabětice platform between the Vražný brook and the Luha valley. The glacial drift is leveled by 5-10 m thick aeolian loess loam - sector 2 (Section 2-2', Fig. 3). 3. The glacial deposits forming a Quaternary platform at the right bank of the Odra River between Jeseník n. O. and Bernartice get narrower due South and enter an overdeepened about 4-5 km wide valley (Section 3-3', Fig. 4) The glacial sequence there, more than 30 m thick, is composed of basal gravel (6-10 m, main terrace) overlain by 15-25 m thick glaciofluvial sand and sandy gravel topped in places by till. More southward the valley is only 2.0-2.5 km across and forms a typically U-shaped trog (Section 4-4', Fig. 5). The valley (Poruba Gate) and its sedimentary filling crosses the European watershed and enters the drainage area of the Black Sea. The sediments are Saalian in age and correlate with the Palhanec and Oldřišov Glaciations (Macoun 1989, Růžička 2004).