Radiocarbon dating of pottery complexes from Neolithic settlements on the Baikal coast
The aim of the study is to summarize all data on the radiocarbon dating of Neolithic complexes of settlements on the Baikal coast, to evaluate their reliability and to clarify the cultural and chronological positions of the different Neolithic periods of this region. The sources were the results of 113 definitions of 14C from 11 stratified (mostly multilayered) settlements, most of which were obtained as a result of excavations by the authors of this article. The collected database for the 14C dates contains definitions based on samples of different organic composition (charcoal, animal bones and soil). As a basis for identifying the reliability of radiocarbon dates from this area, studies were conducted in the last decade on the multi-layer stratified object Sagan-Zaba II. For this object, a full column of sequential radiocarbon dating was obtained for all Neolithic periods. Targeted studies on the analysis of dates have made it possible to identify the problem of ancient carbon (the so-called "freshwater reservoir effect"). It has been established that age determinations based on the bones of seals significantly overestimate their radiocarbon age. Additional sources of unreliable aging can result from radiocarbon analysis of burnt bones (due to the small amount of collagen in them) and the use of bone samples without species definitions. The dates obtained from soil samples look very conditional. As a rule, their results are wider than those performed on the bones of ungulates in a given layer. They reflect the average values of the age of soil formation, and not the time of the existence of the archaeological complex. At present, the most reliable dates are those obtained from charcoal and from ungulate bones, as ungulates do not consume aquatic foods as part of their diet. An analysis of the series of dates for each individual layer made it possible to identify compact groups of dates and to isolate several outliers that may have resulted from bones that moved from above or below the layers where they were recovered. On the basis of these analyses, the chronology of the Neolithic complexes of the Baikal coast settlements is as follows: Early Neolithic (with Khaita type and net-impressed pottery) - 14 dates of the range 7214-6123 BP (8160-6910 cal BP); Middle Neolithic (Posol'sk type of pottery) - 3 dates, ranged 5852-5597 BP (6750-6310 cal BP); Late Neolithic (featuring smooth-walled pottery decorated with various stamp impressions, dotted-comb stamp predominates) - 20 dates, ranged 4967-4217 BP (5840-4650 cal. BP). In general, out of 113 definitions, most of the 14C dates are not suitable for chronological reconstructions. These include the dates obtained from seal bones (before the development of "reservoir" corrections for Lake Baikal), soil and burnt bones. By employing a series of dates, rather than relying on single definitions, it is possible to detect outliers. The most reliable dates are those obtained from charcoal and from ungulate bone. If possible, it is necessary to repeat radiocarbon definitions of settlement complexes (by AMS dating) obtained over the last century.