GLACIOLACUSTRINE KAME TERRACES AS AN INDICATOR OF CONDITIONS OF DEGLACIATION IN LITHUANIA DURING THE LAST GLACIATION

Abstract

Over the recent years, while executing the geological mapping of the Lithuanian territory at a scale of 1:50 000, attention have been given to kame terraces adjoining the recessional marginal ridges left by glacier lobes of the Last (Upper Nemunas, Late Weichselian) Glaciation. For a long time, only the kame terraces formed between dead ice blocks and the internal (with respect to the glacier lobe), i.e. proximal slopes of the marginal morainic ridges have been known. During the process of mapping, the kame terraces have been subdivided into the glaciofluvial (sand, gravel) and glaciolacustrine (clay, silt) according to their lithological composition. The glaciolacustrine kame terraces adjoining the distal slopes of the recessional marginal morainic ridges of the Middle Lithuanian, North Lithuanian and Paju ¯rio phases of the Last Glaciation have been found and examined. The origin of these terraces could be explained only by the hypothesis that the accumulation of the above-mentioned marginal ridges and kame terraces took place between the margin of active ice lobes and the blocks of dead ice. Supposing that when the glacier of the Last Glaciation was melting, it was the arial and not the frontal deglaciation that was definitely dominating. The cold periods of glacier activation (so-called stadials and phasials) were changed with warmer periods. However, the latter periods were too cold and too short that the territory could be deglaciated completely, that is why they cannot be interpreted as interstadials or interphasials according to the climatostratigraphic criterion.