This article examines the geological and geomorphological context and the chronostratigraphic correlation of Paleolithic sites within the Krasnoyarsk Basin. The study is based on current understanding of the Late Quaternary history of the extraglacial zone of the Yenisei River. It has been established that the Yenisei River valley within the basin was impacted by two megafloods during the Late Pleistocene. These floods resulted from the breach of the ice-dammed lake in the Darkhad Basin in the upper reaches of the Yenisei River: the Chanin flood (approximately 80-70 ka BP) and the Divnin flood (approximately 25-20 ka BP). Following the latter flood, the alluvial deposits of the First Above-Floodplain Terrace (I NPT) began to form, represented by a set of characteristic facies, which constitutes the only transit terrace in the valley. The Krasnoyarsk Basin contains the highest concentration of Paleolithic complexes in the Yenisei River basin. The identified geomorphological and stratigraphic features of the Paleolithic sites, supported by previous chronometric data and new radiocarbon (14C) dating, indicate that these megafloods were a limiting factor for the location of Paleolithic campsites. Paleolithic complexes dating to the early stage of the Upper Paleolithic are associated with the Kurtak pedocomplex, which is widespread on watersheds, slopes, and the sides of log (ravines) significantly removed from the main channel of the Yenisei River. Consequently, the cultural layers of these sites remained outside the inundation zone of the last megaflood. A number of sites from this period, located in areas of potential erosional scouring, were preserved due to their position in erosional shadows and their high hypsometric elevation. During the first half of the late stage of the Upper Paleolithic (19–18 cal ka BP), the prehistoric population inhabiting the basin preferred to settle on slopes and watersheds near temporary watercourses (log/ravines) and at significant distances (up to 8 km) from the Yenisei River valley. From 18 cal ka BP onwards, Late Paleolithic populations began to prefer the shoreline and the contemporaneously forming alluvial terrace deposits of the Yenisei River and its tributaries, as well as the gentle slopes descending to the terrace, located at elevations of up to 35 m. Sites from this period are primarily associated with alluvial and subaerial deposits of the terrace, at heights ranging from 8 to 35 meters.

Western Siberia, encompassing both the plain and its mountainous periphery, experienced a cyclical environmental regime during the Pleistocene. Periods of gradual ecosystem evolution characteristic of interglacials alternated with less hospitable glacial phases. These glacial intervals were defined by the establishment of formidable natural barriers and culminated in brief but intense episodes of extreme geomorphic activity. This activity, driven by catastrophic megafloods, resulted in rapid, large-scale denudation and sediment accumulation. During glacial maxima, extensive portions of the northern region were dominated by ice sheets and their associated proglacial ice-dammed lakes. For understanding the dynamics of Pleistocene human dispersal and settlement in this region, the glacial stages of Samarovo, Taz, and Zyryanka are of particular importance. In the Late Pleistocene, specific proglacial basins, with reconstructed water levels at approximately 70 m and 40 m above present sea level, played a pivotal role in shaping the northern landscape. In contrast, the environmental history of the southern plain was predominantly influenced by a series of Gorny Altai megafloods. During the glacial megafloods originating from the Gorny Altai, the Ob and Irtysh basins functioned as a unified drainage system interconnected by spillways across the Ob-Irtysh watershed. Three major megafloods caused extensive denudation across the lowlands of southern Western Siberia and the territory of the present-day left bank of the lower Ob River. The final megafloods event in the Ob and Irtysh valleys performed intensive erosional work and, simultaneously, blanketed the underlying landscape with a thick mantle of parallel-laminated sands and silt sands. This mantle onlapping all deposits older than the second half of MIS 2. Within the Ob-Irtysh basin, Paleolithic sites predating the Late Paleolithic are found exclusively outside the areas impacted by the megafloods. Stratified sites within the scabland formed by the last megafloods, dating to the Late Paleolithic (Last Glacial Maximum), belong exclusively to its final stage. Exceptions to this pattern are sites such as Kushevat and Bobkovo, whose preservation is attributed to local topographic features that shielded them from the full force of the floods.

The soil-sedimentary sequence of the Middle Paleolithic archaeological site Khotylevo I includes five pedogenetic levels MIS 5a–MIS 2: MIS 5a Early Valday oxbow lake gyttja and related synsedimentary hydromorphic paleosols; a sequence of interstadial MIS 3 soils consisting of two well-developed paleosols, one of which has a complex polygenetic history of formation; a block of ephemeral, poorly developed MIS 2 gleyic paleosol horizons; and a Late Valday pedogenesis stage, without prominent signs of gleization or cryogenesis, presented by a Bw horizon of Trubchevskaya soil. Based on the highlighted paleosol markers, we compiled a consolidated soil-stratigraphic profile of the Khotylevo I site, which supplements the scheme developed by A. A. Velichko and colleagues in 1961–1997, being more detailed in the MIS 3–MIS 2 interval. The Middle and Late Valday soil-sedimentary sequence presented in the section was used as a tool for local correlation with the Upper Paleolithic sites Khotylevo 2 and Khotylevo 6. This correlation casts doubt on the assignment of pedosediments which contain Upper Paleolithic industries to the Krutitskaya phase of the Mezin soil complex (MIS 5a) by the researchers of the aforementioned sites. Based on the results of our research, these pedosediments correlate with the humus-accumulative horizon of the MIS 3 paleosol, which more closely agrees with the understanding of the age of Eastern Europe’s Upper Paleolithic.

The article is devoted to the problem of chronostratigraphic correlation of geological and cultural deposits in loess-like loams at Kostenki-Borshchevo Paleolithic area. The history of Gmelin paleosoil identification, its main characteristics and possible analogues in the region are considered. In the archaeological periodization, the Gmelin soil was often used as an important marker, which was associated with the finds of Gravettian settlements and, in particular, the Kostenki-Avdeevo archaeological culture. Based on the analysis of recent radiocarbon dating data and ideas about the development of cultural traditions in the Kostenki Paleolithic, it is concluded that Gmelin soil cannot be considered a reliable chronostratigraphic marker until special paleopedological studies of various paleosols in the cover loams.

This study presents mineralogical and geochemical data which characterized key layers of Pleistocene sedimentary strata of the South Chamber of Denisova Cave (Altay, Russia). A set of proxies of depositional environment and sources of matter was used and discussed: silicate weathering indexes CIA and ICV, ratios of major (CaO/SiO₂, P₂O₅/SiO₂, Na₂O/SiO₂ etc.) and trace elements (Sr/Ga, Na/Ga, Zn/Ga, etc.), enrichment factors (EF_Ca, EF_Na, EF_P, EF_Sr, EF_Zn, EF_Cu), and index minerals (calcite, apatite, mica, chlorite, plagioclase). The depth-related variations in these proxies reveal the change in the source of materials that filled the cave and their individual contributions over different time intervals. Strongly weathered, mature products were only identified in the oldest layer 19.2 (pre-MIS 9), which is free from both archaeological and paleontological finds. Bones, coprolites and organic matter, as well as immature silicate weathering products, were first noticed in layer 19.1 (MIS 9–8 boundary) and are common throughout younger sediments. A linked growth in the content of bioapatite, phosphorus, and zinc in cultural layers 18–13 (MIS 7–4) reflects an increased input of biogenic materials into cave deposits. For the first time, we have quantified the contents of bioapatites from different sources, such as bone tissue and coprolites of osteophage predators, in the bulk sediment. The abnormally high phosphorus enrichment, linked with hyena coprolites, was found in layers 14 and 13 and indicates an episode of maximum biotic activity in the Southern Chamber. In the layers 18 and 16.2 the key phosphorus-host is bone bioapatite, which was mainly supplied into sediments through the activity of humans and non-osteophagic predators. This approach should be the basis for the development of a universal mineralogical and geochemical methodology for analyzing multi-sourced cave sediments.

The reconstruction of the history of the development of the Vishera River valley was carried out on its flat section (from Krasnovishersk to Ryabinino), where a series of archaeological sites from the Neolithic period to Russian colonisation are known. Field research included a description of the terrace levels in the valley and alluvial terrace sedimentary successons; palaeo-channel analysis was used to identify floodplain generations. The chronological basis for the reconstruction comprises the results of radiocarbon and luminescence dating. Two levels of floodplain terraces (the so-called ‘zero’ and first) and four floodplain generations have been identified in the Vishera River valley, and four stages of the history of the Vishera River valley have been reconstructed. The most ancient (first) stage (31–26 thousand years ago) is evidenced by an old alluvium in the base of the high floodplain terrace. During the maximum of the last glaciation (20–16 thousand years ago, stage 2), the valley continued to form and alluvium continued to accumulate, which now forms the first floodplain terrace. Permafrost structures have been recorded in the alluvial top of this terrace, indicating the significant role of cryogenesis at that stage. In the Late Glacial period (~15.000 years ago), river incision began, leading to the formation of a lowest terrace level (‘zero’ terrace); at that time, active accumulation of aeolian deposits occurred on the surface of the first terrace, the thickness of which in some places significantly (up to 3–4 m) increased its height relative to the river level. The formation of the floodplain, consisting of four groups of generations, took place in the Holocene, and most likely, the ‘zero’ terrace was partially flooded by seasonal flood waters which led to the swamping of its lower areas. At the beginning of the Middle Holocene, humans began to settle in the Vishera River valley, mainly on the dune-covered elevated fragments of the zero terrace along the river channels and on the shores of oxbow lakes. Probably later, due to the active transformation of the floodplain and channel 
landforms, which was largely unpredictable for ancient and medieval humans, the choice of settlement places was also determined by that principle.