Evolution of soils and dynamics of the climate of steppes in the southeast of the russian plain during the late eneolithic and bronze ages (fourth to second millennia BC)

Abstract

On the basis of studies of subkurgan pedochronoseries, the main mechanisms of the development of soils of arid and desert steppes in drained landscapes of the southeastern Russian plain in the Late Eneolithic and Bronze ages (6000−3000 years ago) were established. During the fourth to third millennia BC, evolution of soils took place at the level of subtypes with a shift of boundaries of soil subzones toward the north. In each of the studied natural regions (Central Russian Upland, Volga Upland, Ergeni Hills, and Caspian Depression), an increase in the aridization of the climate in the second half of the third millennium BC can be distinctly traced, owing to which a convergence of the topsoil with the transformation of dark-chestnut, chestnut, and light-chestnut soils in chestnut-like semiarid soils, which dominated the region 4200–3900 years ago, occurred. In the first half of the second millennium BC, another change in the conditions of soil formation occurred that was caused by an increase in the degree of atmospheric humidity. It induced the divergence of the topsoil with a secondary formation of areas of zonal chestnut soils and solonetzes in place of chestnut-like soils by the middle of the second millennium BC. The obtained data gives reason to suggest that the age of modern chestnut solonetz complexes of the region does not exceed 3500 years.