The Sukhaya Mechetka is the most important Middle Paleolithic site in the Eastern Europe. The paper presents the analysis of the section, including its cultural layer, in the context of stratigraphy and paleogeography of the Lower Volga River region. The structure of the section represents 11 main stages of sedimentation and paleogeographic evolution of the site territory, which are closely related to global and regional changes in the climate and the level of the Caspian Sea. The base of the section reflects the stage of a river existence on the territory of the site that flowed into the Volga River estuary, formed by the Early Khazarian transgression of the Caspian Sea at the end of the Middle Pleistocene (MIS 6). A long continental period of evolution under multi-directional climate fluctuations of different amplitudes from the Mikulino interglacial (MIS 5e) till the Late Valdai glacial epoch (MIS 2) is reflected in the middle part of the section. The Late Khazarian and Hyrcanian transgressive basins (MIS 5), as well as the Paleo-Khvalynian stage (MIS 3) of the Caspian Sea did not reach the latitude of Sukhaya Mechetka. The stage of Early Khvalynian transgression (MIS 2, 16 190 ± 200 years ago) during the degradation of Ostashkovo glaciation is expressed in the upper part of the section. Three paleosoils have been found that reflect the warming periods of the MIS 5 stage and are related to its 5e, 5c and 5a sub-stages. The middle paleosoil contains a cultural layer assigned to the Micoquian/KMG community of Northern Eurasia. The climate was moderately warm during the Neanderthal settlement of the territory, steppe landscapes dominated the interfluve, and the forests grew in the balka. The Hyrcanian transgression of the Caspian Sea with an estuary in the Volga River valley predetermined a high erosion basis and the formation of a balka with a wide bottom and gentle banks. A permanent fresh watercourse attracted mammals which were an object of hunting for ancient men. All this, obviously, became a basis for the organization of settlement in the Sukhaya Mechetka balka. Correlation of the section with detailed studied loess-soil sections of the Lower Volga River region makes it possible to determine the age of its cultural horizon in between 97-110 thousand years ago.

As a result of complex interdisciplinary studies, the existence of much more complex glacial-interglacial climatic rhythms than previously thought was revealed in the Neopleistocene history of the Oka–Don Loess Province. We have established nine warm epochs (seven interglacials, two interstadials, including the Holocene) and eight interglacial epochs or cooling periods over the last 0.7–0.8 m.y. The sequence of the development of the ice sheets and the interglacial periods in the Early and Middle Neopleistocene is significantly revised. In the Early Neopleistocene, another glacial-interglacial macrocycle was identified in the interval between MIS 15 and MIS 12. In the Middle Neopleistocene, an alternation of three macrocycles was established instead of two previously identified ones. The concept of landscape and climatic changes within interglacial epochs has become more complex. The paleopedological materials on the Ilyinka, Muchkap, Kamenka and Mikulino interglacials indicate the existence of several phases within them, corresponding to two or more optima. It is shown that the Muchkap interglacial was the most humid and heat-provided thermochron in the series of interglacial epochs. The evolution of interglacial pedogenesis and the natural environment over the last ~780 000 years has been traced. The main climatic trend that determined the development of the natural environment and the evolution of landscapes in the geological history of the Oka–Don Loess Province was the directed cooling from the Early Pleistocene Interglacial epoch to the Late Pleistocene epoch. A similar trend toward increasing severity and continentality of the climate is observed for the glacial epochs. The interregional correlation of deposits and events of the Neopleistocene in glacial and periglacial regions in the Don, Dnieper, Volga, and Kama basins was performed.

As a result of complex investigation in the Central Russian Loessal Province, detailed lithologic, geochemical, paleopedological, and paleontological characteristics of the young deposits of the stratotype section Mikhailovka are obtained. They provide the basis for facies genetic differentiation, stratification, and correlation of particular horizons chronologically coordinated by paleopedological and paleontological data with the geological scale of the Neopleistocene. The loess–soil sequences corresponding to climatolites of the Lower, Middle, and Upper Neopleistocene are established and characterized. In dynamical history of the Central Russian Periglacial Loessal Province, thirteen paleogeographical stages of natural–climatic changes (seven warm interglacial and interstadial epochs, six cold epochs alternating with them) are revealed. A rhythmic climatic substantiation for the stratigraphical division of recent sediments in the investigated region is provided.

Specific features of the formation and distribution of periglacial loess association in the Volga region are discussed. Based on generalization of the results of the systematic paleogeographic analysis, the paper presents a comprehensive characteristic of the polygenetic and polychronous loess rocks. The results show regional specifics in the structure and composition of loess rock horizons confined to different-aged paleogeographic zones of the Russian Plain. Provincial discrepancies in the distribution and thickness of loess rocks are demonstrated in the summary map. Comparison of the complex characteristics of the loess rocks provides insight into the general trend of spatiotemporal variability of their structure and composition. Latitudinal zonation is manifested in the thickening of loess rock sequences along the distal direction of the paleoglacial zone (on the average, from 1.3 m to 5–10 m or more) and is usually accompanied by increase in contents of the silty material and carbonates and degree of sagging. Moreover, the stratigraphic structure of sections becomes more complicated with increase of the age interval of loess–soil series. The spatiotemporal trends, which are revealed in the development and periodicity of loess formation, have a great significance for the reconstruction of paleogeographic events in the Neopleistocene.

Complex investigations in the lower Kama River basin yielded the first detailed lithogeochemical, paleopedological, and paleontological data on recent sediments constituting the Razdol'nyi and Rybnaya Sloboda reference sections. These data served as a basis for facies-genetic discrimination, subdivision, and correlation of defined units with the Pleistocene time scale using paleopedological and paleontological data. This allowed environmental changes to be reconstructed for the Middle Pleistocene to Holocene period and stratigraphy of recent sediments in the region in question to be substantiated using climatic rhythms.