Dynamics of the Middle Holocene Paleoclimate in the Steppe Zone of the Eastern European Plain According to the Data of the Study of Soils Buried under Mounds of the Bronze Epoch

Abstract

Soils buried under archaeological monuments of the Bronze Age were studied on three test plots in Orenburg oblast, Stavropol krai, and Krasnodar krai. Kurgan 1 of burial mound (BM) Boldyrevo IV was built in two stages from the second quarter to the middle of the 4th millennium BC by the population of the Yamnaya culture of the early Bronze Age and included four earthen structures. Kurgan Essentukskii 1 was built in the second quarter of the 4th millennium BC (the early Maikop culture) and included four earthen structures. According to archaeological data, the mounds were built during several ten-year periods. In kurgan 1 of BM Beisuzhek 9, three constructions of different periods were identified: the first and second ones of the middle of the 2nd millennium BC (the Novotitorovskaya culture) and the third one of the beginning of the 2nd millennium BC (the Catacomb culture). Buried soils were studied under each kurgan structure, and pits of modern soils were laid outside each kurgan under similar topolithological conditions. A comparative analysis of the morphological and physicochemical properties of buried and modern soils of the chronoseries, as well as analysis of the palynological spectra from the upper horizons of these soils, were conducted. The processes of dehumification, carbonate accumulation, salinization, and alkalization of the studied soils became more intensive from the beginning to the end of the construction periods of all the mounds. The thickness of the humus horizon decreased, and the depth of occurrence of carbonates became closer to the day surface. The percentage of herbaceous plants in the plant association increased noticeably, and species typical for steppes appeared by the end of the construction period of the mounds. The analysis of paleosoil and palynological data shows that the regions studied were characterized by climatic changes—an increase in the mean annual temperatures and a decrease in the precipitation—in the Atlantic period of the Holocene (in the interval of 5500–5300 years ago) and in the Subboreal period of the Holocene (in the interval of 4500–3800 years ago).