Spatial arrangement of sites located near raw material outcrops: a cluster analysis using materials from lower archaeological horizons at the Tolbor-4 site, Northern Mongolia

The article provides the results of distribution analysis of the finds in archaeological horizons 5 and 6 at the Tolbor-4 site (2005 excavations) using a cluster analysis. This collection is the basis for the identification of the Initial Upper Paleolithic technocomplex in Mongolia. However, the site location on a slope and low sedimentation rates make it difficult to study the spatial arrangement of these complexes. The article is aimed to determine archaeological horizons 5 and 6 spatial arrangement considering the condition via using the cluster analysis algorithms. Based on digitisation of coordinates from drawn plans, a dataset was obtained to generate a three-dimensional model and to perform a cluster analysis of the finds distribution from the 2005 excavation. Based on new excavations, which employed total tacheometric recording to determine and collect spatial coordinates, orientations of elongated finds were studied to reveal which processes influenced sedimentation. The k-means algorithm was used for finds with precise coordinate referencing, and the unconstrained clustering algorithm was used for allfinds with only square-meter referencing. As a result, archaeological horizons 5 and 6 were determined as having been minimally disturbed by slope processes that dominated the formation of overlying archaeological horizon 4. Slope displacement affected a portion of AH 5 exposed during the 2005 excavation, which is revealed by specific displacement structures. Concentrations of material distributed perpendicular to the slope, alternating with areas of the same shape with only sparse finds, are characteristic of archaeological horizon 4 and were also observed at other sites in the Tolbor group. The remaining part of archaeological horizon 5 appears to reflect overlapping traces of primary reduction and activity using strongly modified tools. We have determined archaeological horizons 6 as a workshop-camp located near raw material outcrops formed by a short-term occupation. These spatial distributions reflect a part of subsistence strategy of highly mobile population, associated with the primary preparation of lithic raw materials for further transportation.