Unique Landscape Originated by Cataclysmic Glacial Floods at the Weichselian Glaciation Decline in North-Eastern Poland

Rapid climate changes during the decline of the Weichselian glaciationGlaciationWeichselian (Vistulian) caused a sudden increase in meltwaterMeltwater activity and significantly transformed land relief in north-eastern Poland. The sudden release of meltwater from glacial lakes was responsible for the development of the MegafloodMegaflood Landform System that includes subglacialSubglacial and proglacial subsystems as a unique landscape pattern in north-eastern Poland. These subsystems, respectively, constitute a part of subglacial and marginal landsystems. The main pathways of subglacialSubglacial floodwater flow are represented by exceptionally large tunnel valleysTunnel valley with subsequent erosional features attributed to catastrophic drainage of subglacialSubglacial lakes located likely in south-western Lithuania. Features indicative of subglacial outburst floodsFlood, flooding are glacial curvilineations (GCLs)Curvilineations, glacial (GCL), which appear as large ridges separated by inter-ridge troughs. The proglacial landscape is represented by main (first-order) landforms, including two floodwater flow pathways in the proglacial area: the Eastern and Western Spillways. The secondary components of this subsystem comprise a suite of landforms including outburst fansOutburst fan, scablandScabland-like topography and mega-scale superimposed bedforms developed in the area of outwash plain. The Megaflood Landform System recognised in north-eastern Poland is the youngest geomorphic landscape in the European Lowland, and originated from cataclysmic glacial lake-outburst floods that were one of the major factors controlling the formation of the European valley system.