BULLETIN OF ARCHAEOLOGY, ANTHROPOLOGY AND ETHNOGRAPHY ¹ 6 (2006)
Paleoecology
Distribution of the Middle Pleistocene paleolithic sites in the south of West (Mountain Altai), Middle (Ust-Izhul 1), and East (the Angara upstream basin) Siberia, as well as in Yakutia allows to expect a possibility to discover sites of the same age in the central parts of Middle Siberia. That is why the new data on the environmental conditions of the Middle and the firsr half of Late Pleistocene being of interest for investigation of paleolithic man who could already habit at that time in the central regions of Middle Siberia. The integrated investigation of the Bedoba profile on the Irkineyevaya river northward of the lateral Angara provides new data for reconstructing the climate and vegetation of the greater part of the Kazantsevo and Zyryanovo Time (the first half of Late Pleistocene).
The Bedoba profile strips the constrative alluvium strata (enclosed its description together with lithic-and-facies composition) constituted by a number of the facies typical of valley rivers: channel gravel, old river bed peat bog and clays, flood plain facies below, while above — sands of the constrative alluvium crowned with lenses of loam from the facies of the secondary water bodies. Above the latter, we obtained 14C-date of 52100±1680 years (ËÓ-5044), while below, all the dates were over 53–60 thousand years. The old river bed peat bog gave U/Th date of 120±13 thousand years which evidences the Kazantsevo age of the alluvium underlying the constrative one. The malacofauna (5678 tests obtained from the old river bed alluvium) was classified into 23 taxons with lack of the most typical representatives of the loessial complex, though with predominance of Gyraulus albus over G. laevis, to be typical of the Interglacial optima. In the channel alluvium there were numerous Unio tests, nonavailable in Siberia today. The carpological analysis of the old river bed facies showed rich flora (102 taxons). There were three stages evidenced in the development of the vegetation: 1) mixed forests of the Interglacial type constituted by spruce, fir, birch, etc., accompanied by Sambucus racemosa, Brasenia, etc.; 2) above — forests with signs of temperature falling; 3) still more cold-loving, rather interglacial, flora.
The botanical analysis of the peat showed occurrences of fir throughout the thickness of the peat bog.
Palynologically, subject to investigation being the entire profile. There are eight stages identified in the vegetation development. Under accumulation of the channel alluvium, there grew coniferous forests with pine and fir, with admixture of hazelnut, oak, and cloudberry; in the constrative alluvium, after break in sedimentation and erosion , subject to investigation being three stages in the evolution of periglacial vegetation. For the first time, there was obtained a regional characteristic of the Kazantsevo Interglacial. Up to now, the latter was known only with regard to the Angara and Yenisei valleys where the climate and vegetation was different from the regional ones both today and during the Pleistocene. When removing from the great rivers' valleys into the optimum of the Kazantsevo Interglacial, there was predominance of hazelnut among broad-leaved species, whereas in the Angara and Yenisei valleys that same period was marked by predominance of oak among broad-leaved species. Subject to discussion being other differences between the regional vegetation and that of the great rivers' valleys. According to the data of different groups, the optimum of Interglacial was positioned on different stratigraphic levels: according to malacofauna, it was in the clays underlying the peat bog; according to macroflora, in the middle of the peat bog; while according to palynology, it was above the peat bog. The article discusses possible reasons of such non-conformity. One of the latter could be a complex structure of the Kazantsevo Interglacial in the central parts of Middle Siberia, comprising 2(3?) optima.
The article is based on the author’s publication in the early 1990s on possible existence of the anomalously warm area on the shelf of the Barents Sea during the period of the latest glacial maximum. That purely geographical idea was stringed with the facts described in the given article. The author realizes a hypothetical nature of his constructions in the historical aspect, presenting this paper not as infallible truth, but as a curious hypothesis emerged from the isolated specific evidences taken together.