Attributes of controlled-use of fire: based on materials discovered in settlements of Neolithic and Paleometal ages in Northern Angara region

Purpose. Modern field archaeological studies allow recording a large number of different burning traces: fireplaces, combustion features, hearths, etc. There is a problem of determining the genesis of these objects during excavation and desktop processing of materials. Burning traces from the fires of ancient man and burnt stumps can seem outwardly similar when discovered at the excavation site. Analytical and experimental studies have shown that the traces of burning differ in the thickness of filling, where the thickness from 5 to 15 cm can be a «dividing line» between the controlled and permanent use of fire. Our monitoring of the buried evidences of forest fires has shown that burning traces of burnt stumps and other object have the filling depth of about 2-5 cm. The purpose of this study is to verify the thickness of filling as a differential feature. The subject matter of the study is to identify the signs associated with the thickness of filling, provide the analysis of their interrelations, and give the definition of «threshold requirement». This was done by means of statistical analysis on a wide range of objects. Substantial archival sources were involved in this study. Results. We conducted statistical analysis of 220 burning traces in order to verify our assumption. The objects were identified in 19 settlements of Neolithic, Bronze and Early Iron Age in the Northern Angara region. We established interrelationships between individual morphometric features of the samples and determined that the filling depth correlates with the angle compliance coefficient and lamination of filling. The use of statistical methods has made it possible to determine the «threshold requirement» for differentiating the objects under study. The traces of controlled use of fire have a multilayered filling capacity of more than 9 cm and an angular compliance coefficient of more than 0.6. The traces of burning with a fill depth of less than 9 cm and an angular matching coefficient of less than 0.6 are interpreted as traces of uncontrolled use of fire, which indicates that no external influence was exerted on the process of combustion. Conclusion. Presently, archaeology faces issues of interpreting the use of fire by man in antiquity. As our research shows, they can be solved by a comprehensive study of the burning traces that can be differentiated into traces of controlled and uncontrolled use of fire identified with instrumental methods. We can study combustion features by methods of statistical analysis, verify the hypotheses on the nature of burning traces at a certain archaeological site and reconstruct individual pyrotechnic devices. The results of statistical analysis are applied to the interpretation of combustion features. An unambiguous assessment study of combustion features is impossible if we have not obtained all the necessary measurements.