Climate and Vegetation Changes over the Past 7000 Years in the Cis-Ural Steppe

Resumo

A multilayered archaeological site Turganik Settlement in the valley of the Tok River in the Cis- Ural steppe (Orenburg oblast) was examined with the use of paleopedological and microbiomorph methods. Ancient people inhabited this area in the Latest Neolithic (Eneolithic) (5th millennium BC) and Early Bronze (4th millennium BC) ages. It was found that cultural layers dating back to the Atlantic period of the Holocene had been formed under conditions of a predominance of grassy–forb vegetation with a small portion of tree species and dry climate; the ancient settlement was not affected by floods and was suitable for permanent living. It is probable that soils of the chestnut type with salinization and solonetzic features were developed in that time. The final stages of the accumulation of cultural layers were marked by strong shortterm floods, whose sediments partly masked the features of the previous long arid epoch. The highest degree of aridity was at the end of the Atlantic period. In the Subboreal and Subatlantic periods, soils of the meadowchernozemic type were formed; the spore–pollen spectra of these periods are characterized by a higher portion of tree species and by the presence of phytoliths of meadow grasses. The climatic conditions were generally colder and more humid, though some short-term aridization stages could take place. Some of these stages are recorded in the thickness of the studied sediments.