On the tripartite system of Pleistocene stratigraphy in glacial accumulation areas

Abstract

Article in French.

ORIGINAL TITLE: Sur le systeme triparti de la stratigraphie du Pleistocene dans les pays d'accumulation glaciaire

The author intends to introduce a tripartite instead of a bipartite division of the Pleistocene stratigraphy with respect to the areas covered with Quaternary glaciers. It is to be regarded as a natural consequence of the prevailing role of climate in the whole history of the Quaternary epoch stressing the importance of the rock- or formation-units in the stratigraphy. Hence the idea to complete Pleistocene stratigraphy by the addition of periglacial units to the glacial and interglacial ones. Analysis of a certain number of Pleistocene profiles from different parts of Poland reveals the great importance of periglacial formation-units in the stratigraphic sequence. Only such periglacial units, as are representative of the cold periods can be herc encountered. In is known that other formations associated with the glacial ones play only a complementary role in stratigraphy. Three types of Pleistocene profiles are distinguished. They display several periglacial horizons but their importance increases southward. The profiles of the first type show fossil periglacial formations but only as complementary ones; complex periglacial units which are the only manifestations of all the cold periods constitute the characteristics of the second type; the third one is to be seen in the profiles where glacial formations are completely lacking and the whole Quaternary bistory of the area is represented by alternating periglacial units and by those due to warmer periods. The succession of secondary phases of the cold periods is also discussed. According to different environments the following phases are recorded in the sediments investigated: 1. a phase of rather severe and dry climate, 2. a cold and humid phase, 3. a third phase chiefly characterized by down-wash processcs. As to the corresponding formations and other periglacial phenomena: the first phase - ice-wedges and evidence of wind-action, the second phase - grezes litćes, rubble fields and congelifluxion and the third phase - formations called - according to Dutch and Belgian writers - niveo-fluvial and niveo-fluviatile.