Sedimentological analysis of slope deposits filling closed depressions in the vicinity of Łódź

Abstract

Article in French.

ORIGINAL TITLE: Analyse sedimentologique des formations de versant remplissant les depressions fermées aux environs de Łódź

Covering formations in small, enclosed basins that occur in the region of Łódź have been investigated. As the underlying organic lacustrine deposits have not previously been studied palynologically, it is not yet possible to say whether they correspond to an interglacial or to an interstadiał phase. In either case, they cannot have originated prior to the Eemian because they are overlain only by slope deposits and the basins occur in an area whose last ice-cap was that of the penultimate glaciation. Hence, the periglacial formations investigated should be attributed to the cold period of the ultimate glaciation or, at least, to one of its phases.

The main research objective was to distinguish the sedimentary characteristics of the formations in question in order to obtain a basis upon which some data relative to the climatic fluctuations occurring during a cold period, could be derived by inductive reasoning.

From these sedimentological data, the following sequence of climatic fluctuations and correspondent processes has been deduced: (a) cold and dry – vigorous wind action and cryoturbation, (b) cold and humid – congelifluction, (c) relatively warm – vegetation and pedogenic processes, (d) cold and dry – strong wind action, (e) cold and humid, perhaps warmer – downwash and weak congelifluction, (f) cold and somewhat dry – cryoturbation.

Such conclusions relative to the question of climatic fluctuations during a cold period, especially such a sequence in which cold and dry conditions prevail at the onset of a cold period, widely differ from the views commonly held on this problem.