Zlodowacenie Wisły w rejonie Bramki w zachodniej części Pojezierza Mazurskiego

Abstract

W rejonie Bramki występują dwa poziomy gliny zwałowej ostatniego zlodowacenia. Lądolód fazy pomorskiej dotarł do linii Bożęcin-Bramka-Jez. Piłąg. Na jego przedpolu powstał sandr formowany przez wody roztopowe płynące z bramy lodowcowej Jez. Narie. Analiza poziomów sandrowych pozwoliła ustalić cztery etapy zaniku lądolodu fazy pomorskiej. The Vistula Glaciation in the Bramka region in the western part of the Mazury Lakeland The area subjected to investigations is situated in the north-western part of the Mazury Lakeland on the boundary of the Iława and Olsztyn lakelands (Fig. 1). The depth of the Quaternary deposits ranges from 144.5 to almost 202 m. The Vistula Glaciation is represented by two tills (Fig. 3), the age of which has been determined with relation to the site of the Eemian Interglacial deposits in Dzierzgoń. These tills correspond to the Leszno-Poznań and Pomeranian phases. During the Leszno-Poznań Phase the Bramka region was wholy covered by the continental glacier. At that time a lot of subglacial channels originated, fulfilled with dead ice during the continental glacier recession. During the Pomeranian Phase this region was in an intermediate zone between the Vistula glacier tongue and the Mazury glacier tongue. It was the area of intensive outwash water flow which flowed off freely to the south and south-west to the outwash valley of the Upper Drwęca River. The main outflow of melt waters lay at the Narie Lake glacial channel mouth (Fig. 4). The Pomeranian Phase glacier reached the Borzęcin - Bramka - the Piłąg Lake line (Figs 2, 4A). The main feature of the maximum extension of the Pomeranian Phase is the lack of frontal moraine forms with strong outwash accumulation. Four outwash horizons (I, Ia, II, IIa) have been distinguished, the highest one (I) connected with transgression and maximum extension of the Pomeranian Phase, and the horizons Ia, II and IIa reflected consecutive stages of the glacier recession (Fig. 4).