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The specificity of cultural layer transformation by soil forming processes was examined in humid (Moscow region) and arid (Kalmykia) zones of Russia. The objects studied in the two regions are the Dunino and Ar-Dolong settlements. The former is attributed to the Early Iron Age and the latter to the Bronze Age. Archaeological excavations in both places revealed numerous ancient artifacts occurring in situ which prove the sites having been inhabited in the past. Though located in different natural zones, the investigated objects have two features in common: sandy parent material and the leading role of the anthropogenic factor in the past.

Morphological examination was supplemented with analysis of chemical properties (organic and inorganic matter, total phosphorus, pH). At the arid site, humic acids extracted from the organic matter in the ancient cultural layer have been dated by radiocarbon. Simultaneously, the background soils were also studied.

Though both ancient settlements were abandoned for a long time, the cultural layers have not been buried under later sediments. They stayed exposed and subjected to transformations by soil-forming processes. The duration of the latter was different at the two sites, not exceeding 2 ky in the humid zone and about 3.0-3.5 ky in the arid zone. After people had left the settlements, younger soils developed in the course of pedogenesis, their morphology being similar to the zonal soils. Integrated analyses of soils enable determination of how far the natural processes have gone in the cultural layer transformation. The determination of the total phosphorous provides a means for cultural layer diagnosis with confidence, long after the settlement had been abandoned. It is possible to determine the trends for human-made soil development in different climate zones, from Arenosol to Podzol and Arenosol to Andosol in humid and arid zones respectively.

In the course of time, the cultural layers of ancient settlements are being transformed into zonal soils, no matter the geographical location of the region. However, the rate of transformation, both of individual soil features and of the entire soil profiles is variable. Transformation rate of ancient non-buried cultural layers is higher in the humid environment than in the arid environment. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.