Accumulation of the Mis 2 culture-bearing sediments in Northern Mongolia: fabric analysis of archaeological horizon 2 at the Tolbor-21 site

This article reconstructs accumulation of horizon composed of dense loess-like sediments, which occurs in most of the sites along the tributaries of the Selenga River in Northern Mongolia. At most sites this horizon contains archaeological evidence and shows a system of thin drying cracks. The evidence from archaeological horizon 2 (AH2) of the Tolbor-21 site is used for analyzing accumulation of this horizon. The distribution offinds was studied for clarifying formation and post-sedimentary changes in this archaeological horizon at the Tolbor-21 site. It was discovered that finds formed polygon-like concentrations with voids inside. Two sublayers of artifacts occurring in AH2 (2A and 2B) were observed in the profile. Sedimentation and natural deformation were investigated using fabric analysis - method of establishing spatial arrangement of long axes of objects in archaeological horizon. The analysis of a sample consisting of 261 elongated finds (mostly stone artifacts) revealed accumulation of the AH2 sediments in dry environment with subsequent deformation which was manifested in occurrence of a part of the finds at a high angle (up to 80 degrees). The longitudinal sections and cross-sections of AH2 have revealed that the majority of such finds was confined to sublayer 2A. Thus, deformation of AH2 in arid conditions led to emergence of a polygonal system offractures and formation of the upper sublayer 2A over the main, less disturbed lower sublayer 2B. The data on the sites of the adjacent territories (Tolbor-4, Tolbor-16, and Kharganyn Gol 5) suggests the aeolian origin of the horizon with possible participation of dealluvialprocesses. High share of vertically occurringfinds in the upper part of archaeological horizon and visible spatial concentrations coinciding with the polygonal shape of the fracture system have been identified as distinctive manifestations of drying cracks in the horizon under study.