The problem of inland dunes in Poland in light of structural studies

Abstract

Article in French.

ORIGINAL TITLE: Le problème des dunes intérieures en Pologne à la lumière des études de structure

In the recent problematics of dunes, two groups of questions may be distinguished: 1) dynamics of dune-forming processes, and 2) zonal distribution of dunes showing similar pattern both in their morphology and structure.

Within the first group the following problems are discussed: origin and age of the direct substratum of dunes, their structure and texture, phases of dune development as well as the position of longitudinal, transversal and parabolic forms in evolutional cycle of the dune relief. The stone pavement containing eologlyptoliths underlying the dunes in the Łódź region was most probably formed at the beginning of the waning phase of the Würm. The analytical studies of the dune structure and texture permitted to recognize three and even four (at Katarzynów near Łódź) dune covers commonly occurring in Middle Poland as well as to determine the changes of wind directions and activity during the accumulation of each of dune covers. Identification of soil horizons of Bølling, Allerød and Boreal age; corresponding to the periods of stabilization of eolian processes as well as the palynological data afforded the possibility to reconstruct the course of dune formation and infer the existence of three or - under favourable conditions - even four phases of the dune development. Both the palynological data and ¹⁴C dating prove that these phases were connected with the Oldest, Older and Younger Dryas and with the Holocene (after the Boreal time). However, in the present-day state of investigations it is still difficult to ascertain whether the changes in wind directions caused the regularity in the transformation of one kind of dune forms into another. The transversal and longitudinal dunes seem to appear both as an initial forms of parabolic dunes and as the forms testifying their decline.

The problem of zonal distribution of the dune land-forms cannot be resolved unless it is first stated .whether the dunes originated simultaneously or not in the whole area of Poland. In the light of the investigations so far carried on, the dunes in the Szczecin Basin are probably the youngest. As to the other areas lying within the extent of the older Würmian phases as well as of the Riss and Mindel glaciations the final conclusions cannot be drawn yet. The dunes occuring within larger valleys and basins show a differentiation in shapes due to their vertical situations. The nature of this phenomenon so far is unknown but from among the controlling factors there should be mentioned such as differences in age and influence of local, mainly topographie and hydrographie conditions.