AN EXTENT AND AGE OF THE LAST GLACIATION IN LITHUANIA

The reconstruction of the Late Nemunas (Weichselian) glacial limits is based on geomorphological evidence combined with geological data. The new geomorphologic image of Lithuanian surface obtained from aerial photos, does not confirm the traditional model of the Last Glaciation in which within the Late Nemunas Gruda, Ziogeliai and Baltija stadials were distinguished. The Late Nemunas ice advance is considered to comprise two stages, the older Gruda stadial and the Baltija stadial. The Baltija stadial is correllated with Pomeranian Stage. However, they can be distinquished solely on the lithostratigraphic criteria. The Late Nemunas maximum, i.e. Gruda stadial, is dated approximately to 25,000-22,000BP. The maximum extension of the Last Glaciation has been established in southeastern Lithuania. Here, the outhermost Late Nemunas Glaciation boundary has been traced to the foot of the Asmena Highland. In general, it corresponds to the boundary between different glacial landscape types. However, the precise position of the Last Glaciation maximum is still unknown. There are several marginal morainic complexes north-west of the prominent Baltija Highland, which may indicate three or even four ice front phases of the Baltija glacial advance. Well known Southern, Middle and North Lithuanian phasial limits have been traced geomorphologically. The Middle and North Lithuanian ice-marginal moraine ridges as well as the Pajuris ridge were formed at margins of the active ice, whereas, the South Lithuanian ice-marginal moraine ridge indicate ice front position of the retreating Baltija stage glacier. No sites with Late Nemunas interphase deposits have been discovered in Lithuania.