Eemian and Vistulian (Weichselian) development of the meltout depression on the watershed between the Mroga and Mrożyca Rivers (Central Poland) based on lithological and pollen analysis

Abstract

The lithological and palaeobotanical research conducted in a closed-drainage depression located in the watershed zone between the Mroga and Mrożyca Rivers (Central Poland) allowed for the reconstruction of its palaeogeography in the period subsequent to the retreat of the last ice sheet (Wartanian Stage of the Odranian Glaciation). The purpose of this article is to gather and synthesise the obtained results, as well as to reconstruct the processes of development and filling in the studied depression over the last 135,000 years. The post-glacial evolution of the relief was recorded in the mineral and biogenic sediments deposited on glacial formations. The modern closed-drainage depression is a trace of a fossil extensive glacial meltout depression. The post-glacial development of the land relief within the depression involved three stages, dominated by different types of morphogenesis, i.e. the deglaciation stage during the Wartanian Stage of the Odranian Glaciation, the Eemian Interglacial-Early Vistulian aggradation stage, and the Vistulian aggradation-denudation stage. High thickness of the identified biogenic sediments suggests considerable transformations of the relief of the watershed during the two cycles of temperate climate – the Eemian Interglacial and the Holocene. The thickness of the mineral sediments suggest low dynamics of the environment during the Last Glacial Maximum (LGM), and undermine the hypotheses on the determining effect of periglacial conditions on the character of the relief of Central Poland. The obtained results constitute an inspiration and starting point for another research project concerning the reconstruction of the watersheds in Central Poland.