The Quaternary Ice Age produced a great variety of landscapes in northern Eurasia. Their diversity is expressed in various large elements of physiography – vast plains of sedimentary basins and mountain systems up to 3 km high – all embellished with glaciogenic features. The undelible imprint on northern landscapes was exerted by the outstanding continentality of climate which played a significant role in the Quaternary climate changes of northern Eurasia. It led to the specific Siberian type of inland glaciation in which glacier ice was often fused together with the old and stable permafrost. This resulted in many relict Pleistocene features of the present-day scenery, including thick slabs of fossil glacier ice well preserved in the arctic terrains. This essay deals with main landscape peculiarities of northern Russia originated during the Ice Age as understood by the majority of native and international investigators. A brief note on the influence of Pleistocene inland glaciation on the principal petroleum reserves is added.

In the adjusted longitudinal profile, there are no unidirectional changes in the bed elevations in the alluvial river channel over a long period of time. The prerequisite for the existence of such a longitudinal profile is the constant bedload transport rate along each section of the river without tributaries and its increase at each confluence with a tributary by the amount of the bedload discharge in this tributary. Therefore, to close and solve the system of hydraulic equations for constructing the adjusted longitudinal profile, a formula for calculating bedload transport rate is used, supplemented by the hypothesis of its constant value in the river basin. The inclination of the channel profile calculated in this way decrease with an increase in the maximum discharge and increase with an increase in the particle size and the concentration of the bedload sediments, and the channel bed roughness. Constructing an adjusted longitudinal profile of the river has both theoretical and practical significance. In lowland rivers with low sediment loads, the formation of an adjusted channel profile takes tens of thousands of years, and here it may be of interest to assess the paleohydrological conditions under which such a profile was formed. For example, based on the longitudinal profile of the second terrace of the Oka River, annual water flow was calculated to be half of what it is today, while sediment yield was four times greater than today. In rivers with high sediment loads, such as the lower reaches of the Terek River, the adjusted profile develops over several decades. Here, it becomes practically important to regulate the shape of the longitudinal profile and bring it into line with the adjusted one in order to stabilize channel transformations.

River basins draining the mid- and high-mountain belts of the North Caucasus, exemplified by the Baksan River, are prone to periodic debris floods in their headwaters. These events deliver substantial volumes of clastic sediment to main valleys, driving significant channel transformations downstream. The catastrophic flood generated by the September 1, 2017 outburst of Bashkara Glacial Lake in the Adyl-Su valley provided a pivotal opportunity to assess such impacts on the receiving Baksan River. In this study, morphometric changes were quantified along a middle-course reach upstream of Tyrnyauz. The analysis spans a 40-year period starting from 1984, selected in the immediate aftermath of a preceding major flood, and extends to cover conditions immediately following and six years after the 2017 event. The aim was to elucidate channel dynamics and evaluate system resilience to impulsive disturbances within the context of climatic shifts over the past four decades. Multi-temporal satellite imagery was employed to segment the river network into homogeneous reaches, with a suite of morphometric parameters subsequently derived for each segment. Controlling factors were identified through Spearman’s rank correlation analysis. The immediate geomorphic response to the 2017 flood was characterized by substantial channel widening, averaging a factor of 1.6, and a shift toward more complex planform morphologies. During the subsequent six-year period without extreme floods, divergent trajectories were observed: continued widening (averaging a factor of 1.3) was detected along 27% of the study reach, while recovery through channel narrowing (20–25%) and simplification toward straighter patterns occurred along one-third of its length. Pre-flood channel geometry was found to be a critical control. Narrower, highly confined reaches exhibited the greatest sensitivity and a meta-stable resilience at the studied timescale. In contrast, initially wider reaches located within valley constrictions not only absorbed the impulsive disturbance but were characterized by a positive recovery trajectory, underscoring the fundamental role of antecedent valley morphology in determining long-term channel response and resilience.

The catastrophic detachment of the Kolka Glacier on September 20, 2002, continues to be a subject of scientific discussions. In addition to the hypothesis of a rock-ice avalanche that directly triggered the glacier’s collapse, a key theory links the event to manifestations of post-volcanic activity within the Kazbek volcanic massif. The aim of this study is to assess the contribution of these processes to the initiation of the disaster. The methodology is based on a comparative analysis of a set of satellite images (Landsat, SPOT, QuickBird) and photo-video materials from the period of September 20–25, 2002, within a GIS environment. It was established that the contours of the main collapse scar remained unchanged in images acquired 8.5 hours before the disaster (September 20) and on the morning of September 21, while a major rock collapse with a volume of 1.2–1.8 million m³ occurred later, on September 22–24. A large depression (130×370 m) on the glacier bed was identified, the formation of which is associated with post-volcanic activity. Its location is spatially confined to a zone of tectonic faults, which serve as conduits for the ascent of deep fluids. It is concluded that the avalanche hypothesis cannot explain the catastrophe’s triggering mechanism, and the most probable cause is a steam-driven explosive event of volcanic origin, resulting from the activation of the geothermal system of the Kazbek volcanic center.

A geomorphological map of the Maashei River valley has been constructed, reflecting the history of its development. The dynamics of the relief after the Little Ice Age maximum (LIA) are associated with the reduction of glaciers and catastrophic exogenous processes and are indicated by changes in vegetation. Since the LIA, glaciers have shrunk by 16.9 km² (38%), their upper limit of distribution has risen by 65 m. In 2013–2021, the relative reduction of glaciers accelerated more than 2 times. The development of forest vegetation on the deglaciation areas since 1968 has led to an increase in its area in the valley by 15%, its upper limit along the slopes of the valley has risen by 50 m. Along the valley bottom, from LIA, the advance of the upper limit of tree growth was about 800 m horizontally and 50–55 m in altitude, of which the rise from 1968 to 2022 is estimated at 32 m. The breakthrough and drainage of Lake Maashei in 2012 was prepared by the growth of the lake from the late 1980s to the early 2000s. The breakthrough resulted in the following: stable drainage of a section of the valley bottom; the formation of a gap in the body of the debris dam, hindering the restoration of the lake; blocking of a large area of the valley bottom with mudflow deposits (the area of the accumulation zone is about 0.85 km²); local changes in the configuration of river channels; mass forest loss in the middle and lower parts of the valley (over an area of about 0.4 km2) and the formation of multiple blockages of tree trunks and debris; undercutting of the slope base by the flow in places where the valley narrows or the flow turns and, as a consequence, a sharp activation of slope processes higher up the slopes. The current geomorphological appearance of the territory has developed as a result of the interaction of relatively slow evolutionary processes and catastrophic processes, which almost instantly from a geological point of view transform it locally.

A combination of morphometric, structural-geological, and petrographic methods yielded new data on the structure and genesis of the Ondomozero and Chavanga Keivy upland (fragments of the Terskie Keivy), one of the most controversial macroforms of the Kola region. A conclusion was drawn regarding the relationship of the Terskie Keivy with fault structures of the Fennoscandian Shield in the southeastern Kola region, which may correspond to structural scarps expressed in the relief in the buried pre-Quaternary surface. These scarps defined the distribution boundary and the overall thickness of marine transgressive deposits preceding the last glaciation. During glaciation, these scarps were associated with areas of glacial deformations, which form the bases of the upland. A detailed morphometric analysis revealed that these thrust and folded glacial deformations are reflected in the upper elevation parts of the uplands as ridge-plateau hills features, sometimes complicated by kame fields with glaciokarst depressions. In the lower elevation part of the northern slope of the upland a parallel ridge relief of supraglacial eskers and a hummocky relief of kames and limnokames are developed. On the southern slope there is a hummocky-ridge relief of push and damp moraines. These results and analysis of data from adjacent areas suggest that the formation of the upland basement is related to the period of advancing and local maximum expansion of the last Scandinavian ice sheet, approximately 21000–17500 years ago. The thrust and folded dislocations were primarily composed of loose sediments from lower and middle Valdai marine transgressions and glaciofluvial deposits. Structural and petrographic studies have determined that the glacier flowed from south to north, from the White Sea glacial stream. During glacier degradation approximately 17500–15000 years ago, a complex of eskers and kames formed, and during several readvance periods hummocky-ridge glacial formations developed on the southern slopes of the uplands. Subsequently, the dead ice blocks melted, and glaciokarst depressions and modern lake basins began to form.

Based on spore-pollen analysis of the section of organogenic sediments on the shore of Lake Lotos, the development of vegetation on the sea coast in the lower reaches of the Tumannaya (Tumangan) River and the southeastern macroslope of the Black Mountains Ridge in the East Manchurian Mountain system over the past 2500 cal. years has been reconstructed. Eight palynozones, describing six phases of vegetation development, were identified as a result of an analysis of the taxonomic composition of pollen assemblages. Their temporal boundaries were determined using an age model constructed using radiocarbon dating data. In phase 1 during warming (2500–1800 cal BP), polydominant forests dominated in the Lake Lotos basin and on the slopes of the Black Mountains, including Pinus koraiensis, Pinus densiflora, Abies holophylla, Quercus mongolica, Quercus dentata, Ulmus japonica, Carpinus cordata, Corylus, Juglans mandshurica, Tilia, and Fraxinus. The plains were covered with sedge-grass and forb meadows. Under conditions of slight cooling in phase 2 (1800–1350 cal BP), the role of broad-leaved plants decreased, but the basic appearance of the vegetation remained the same. A slight warming (1350–930 cal BP) caused the expansion of broad-leaved trees (phase 3). In phase 4 (930–630 cal BP), the distribution of broad-leaved plants again decreased, and among conifers, the share of Abies holophylla and Pinus densiflora decreased. Sedge-reed grassy meadows and reed thickets predominated on the accumulative plains. During the last historical cooling (630–300 cal BP), the distribution of broad-leaved forests decreased (phase 5). Alder-birch forests, sedge, and mixed-grassy meadows became the dominant vegetation types in the valleys and along the seashore. During phase 6 (300 cal BP – present), the forest vegetation increased in abundance with Pinus koraiensis, Pinus densiflora, and Abies holophylla. It is believed that the increase in broadleaf pollen in the pollen spectra was due to wind-blown pollen from the south. Sedge-reed grassy meadows and reed thickets predominated on the accumulative plains. Evidence of anthropogenic influence on the landscapes has been identified, beginning in the Early Middle Ages, with the most significant changes occurring in the last century.