Zhurbin I.V.   Борисов А.В.  

Economic periphery of a medieval settlement according to geophysical and microbiological research

Reporter: Zhurbin I.V.

An interdisciplinary approach to the non-destructive study of archaeological sites was applied in the Kushmanskoe III settlement of the IX-XIII centuries AD – the Finno-Ugric settlement of the Cheptsa river basin ( the Northern part of the Udmurt Republic). The methodological basis of this approach was the comprehensive complementary use of remote sensing and geophysics methods, chemical and biological studies of soil core materials. As a result of many years of plowing, there are no signs of settlement boundaries and planning objects on the archeological site. The use of a complex of natural science methods allowed us to establish the boundaries of settlement sites with different preservation of the cultural layer. The location of the sites of the “preserved” and “destroyed” cultural layer was determined, as well as the site of the “economic periphery” of the settlement was identified.
To identify traces of the cultural layer outside the settlement, a study was made of soil samples from the arable horizon and the underlying subsurface horizon in the catena, passing through the archeological site and adjacent areas outside it. Magnetic susceptibility, content of phosphates, and viable microbial biomass were determined in the samples. The most reliable presence of an archaeological site can be determined by analyzing the phosphate content in the arable layer. It is characteristic that areas with increased phosphate values were also noted outside the external line of defense. Probably, anthropogenic activity in the Middle Ages took place far beyond the borders defined by defensive structures and landscape boundaries. The analysis of changes in the concentration of microbial biomass in the arable and, especially, in the sub-arable horizon leads to the same conclusion. Quite accurately, the presence of the cultural layer is manifested by a synchronous increase in phosphates and magnetic susceptibility. This is the situation observed in the sub-arable layer , which indicates an active anthropogenic transformation of the soil, which occurred far beyond the boundaries of defensive structures. It is characteristic that this can be found in the sub-arable horizon , where the soil could be preserved, synchronous with the time of functioning of the archaeological site. We suggest calling this area the " economic periphery " of the settlement and treating it as part of a heritage site.
It is shown that only geochemical and microbiological studies of soils are reliable signs for identifying the area of "economic periphery". An indirect sign of such a site may be an inhomogeneous zone in the thermal imaging image, the location of which correlates with randomly located anomalies of magnetic prospecting caused by accumulations of pyrogen-transformed soil material resulting from plowing and erosion processes. The results of complex natural science research have been confirmed by archaeological methods.

The study was supported by the Russian Foundation for Basic Research (Project No. 18-49-180007 р-а).

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