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4. AGE OF THE PLENIV1STUL1AN DUNES; DUNE-FORMING PHASES

In the light of the investigations presented in this paper, it is possible to submit a propos i tion that the role of aeolian processes during the Pleni vistu-lian, and their morphological effects were greater than it has been assumed till no w. Not only aeolian coversand plains but aiso dunes were formed as a result of aeolian activity. These dunes differ in form and stmeture from the commonly known Late Glacial dunes, and perhaps because of this fact they were not recognized as dunes. They probably occur in the whole, broadly understood periglacial zonę of the last glaciation.

The existence of the Plenivistulian dunes changes our opinion about the dune-forming phases of inland dunes. However, it should be stressed that the TL dated dunes examined by the author fit well in the phases of aeolian activity distinguished in the PIenivistulian.

The following development phases of inland dunes can be distinguished (Table 1):

—    Phase I /Żuków/ (30-20 ka BP) — between the Denekamp Interstadial and Brandenburgian (Leszno) Stadial, a counterpart of aeolian accumulation of the Older Coversand I. This is the first development phase of the Pleni vistu-lian dunes, which occurred on the tum of the Interplenivistulian and Upper Plenivistulian.

Żuków dune type: fiat linear dunes

—    Phase II TJściąź. Kazanów/ (20—15 ka BP) — between the Brandenburgian (Leszno) and Pomeranian Stadials, a counterpart of the aeolian accumulation of the Older Coversand II. This is the second development phase of the Plenivistulian dunes, which occurred in the Upper Plenivistulian.

Kazanów dune type: longer fiat linear dunes.

—    Phase III (15—8 ka BP) — the Late Glacial dune-forming phase, a counterpart of the aeolian accumulation of the Younger Coversand I and Young-er Coversand II.

Dune type: parabolic and ridge dunes.