PLANATION OF MOSCOW GLACIATION PERIGLACIAL ZONE DURING POSTGLACIAL EPOCH

Abstract

Data of lithologic and spores and pollen analysis were used for reconstruction of the history of postglacial sedimentation in the relict hollow of melt water runoff at the south watershed of the Protva river (Kaluga Region). In the end of the Middle Pleistocene when the melt water runoff dried out, weak drainage lake appeared and quickly turned into marsh (dense peat of more than 1.5 m thickness). The middle of the swamp period corresponds to optimum of Mikulino interglacial (OIS 5e). Climate snap in the Early Valday caused flooding of the hollow and sedimentation of 4.5 m of lacustrine siltstones during the interval 120-100 ka B.C. They are overlain by 2 m of Holocene peat, i.e. accumulation was absent during the most part of the Holocene. Other watershed hollows in the middle Protva basin show the same structure; hence scenario described is typical and may be considered as self-development of relief. Glacial and fluvioglacial relief of watersheds, abundant with closed depressions, was being smoothed in the end of the Moscow and in the beginning of the Valdai epochs (Mikulino optimum – interval of relief stabilisation) due to accumulation in the local depressions. As soon as the first half of the Valdai epoch they turned from the catches for deposits into transit elements along their path to lower layers of relief; the integral system of slope wash from watersheds to valley network was formed.