Abstract
Purpose. The aim of this study is detailed reconstruction of the reduction sequences of the layer 5.1 lithic industry. Results. Through a comprehensive analysis of the material complex from the layer 5.1 we reconstructed three knapping strategies characterizing the industry. The first strategy is based on the usage of the narrow core working surface to obtain blades and lamellar flakes. The second strategy is the alternating usage of the working surface and striking platform aimed at blank production. The reduction sequence is characterized by the usage of narrow surfaces bounded by natural sides. The third strategy is the bladelets and microblades production using one narrow or two adjacent (narrow and wide) working surfaces. The comparison of the material complex of the layer 5.1 with the complexes of layers 7–6 indicates principal differences in the raw material preferences, primary knapping methods and toolkits. Conclusion. Based on the lack of continuity of the primary knapping and the principles of spatial exploitation of Ushbulak site area, we suggest a complete change in the population of the Shilikta valley at the boundary of MIS 3 and MIS 2.