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Geomorfologiya i Paleogeografiya

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No 4 (2016)

Articles

3-14 601
Abstract

Landform morphology created by combined action of endogenous deformations and exogenous (denudation) processes depends on whether these forces performed concurrently or in succession in this study, different formation scenarios for a tectonic arch composed of heterogenous substrates are analyzed based on kinematic modeling techniques.

Following the start of the uplift, a lengthwise zone of softer rocks is being transformed into a gorge with a narrow outlet either in case of tectonic tilt and vertical (block) elevation. V-shaped cross-section is being preserved in the outlet as long as the elevation above base level increases. This scenario is valid for many young alpine regions such as Kopet Dag, Himalaya, etc. After the uplift has been finished, gorges start to widen and become trough-like in cross section, and a progressively widening step starts to form at the base of the arch slope (a pediment). In a block that contains a hard vertical dyke, a gently sloping crest is formed following the uplift start. After the uplift cessation, the crest preserves its form retreating together with the whole arch slope.

Slow elevation of an arch containing a hard horizontal layer results in transformation of the upper part of the arch into a small spherical remnant. At the side of the hard layer, a steep cliff forms that passes below into a conical pedestal produced by denudation in softer rocks. In case if the arch contains a softer horizontal layer the surface of the raising block evolves rather to conical than to spherical form.

15-26 643
Abstract
In mountain areas, adjacent coastal lowlands and continental shelf in the Asian part of Russia a variety of buried valleys is found very different in their forming conditions and morphology. Classification of buried valleys is suggested that shows a great variety types, their formation conditions, morphometric and morphological characteristics. Buried valleys are divided into two main groups: 1) valleys formed in areas of rapid crustal uplifts and differential tectonic movements; 2) valleys formed in areas of tectonic subsidence such as transient areas between uplifting and sinking structures, inversion or inherited tectonic basins, individual valley sections preserved at the crossings of subsiding tectonic blocks, valleys buried in coastal lowlands, valleys buried in continental shelf due to the global sea level rise. In most areas, buried valleys are represented by a combination of different age generations of the above types. The degree of inheritance of the identified types of valleys varies and depends on the type and amplitude of tectonic movements. The larger the amplitude of tectonic movements is, the poorer is the inheritance of river network. In the areas of differential tectonic movements, inheritance may be detected not only for river network pattern, but also for morphodynamic types of river channels and even individual channel forms.

Short communications

27-34 723
Abstract
Modern coastal zone is an open morpholithodynamics system characterized by a set of constant and variable parameters. Estimations of these parameters allows to assess the future development of the whole system. Constant parameters are geological and geomorphologic composition of the coast and its wind-wave mode. Variables are long-period fluctuations of water level due to eustatic variations, tectonic and glacio-isostatic movements. Prediction of the evolution of the coastal zone includes the assessment of the trends of the variable parameters of the morpholithodynamics system. In this study, the above problem is analyzed on the examples of south-eastern coast of the Baltic Sea and the Russian sector of the Caspian sea. The possible rise of the Baltic Sea level by 1.0–1.5 m by the end of the XXI century will result in the further destruction of sea coasts, flooding, waterlogging and salinization of coastal areas, which will lead to negative consequences for industrial, municipal and agricultural infrastructures. In the case of the Caspian Sea, the majority of its coasts regardless of the underwater slope has transformed into lagoons due to the sea level rise in recent decades. Coastal erosion will start only when the sea level reaches the 1929 yr stage from which the sea level drop started in the mid XX century. At this stage, a noticeable change of surface slope occurs. At the majority of Caspian coasts activation of coastal erosion will occur when the sea level rise above – 26 m a.s.l.
35-42 812
Abstract
The information resource (IR) “The Magellan Seamounts (The Pacific Ocean)” was produces. This IR embodied original results of field works and GIS-technologies of morphometric data’s processing and published materials on the geomorphology and geology of Magellan seamount’s guyots. The IR includes the website, the geoinformation system in the ArcGIS Online, and the database on 26 guyots. The IR is located on http://guyot.ocean.ru/ and provides researches with especial information about the morphology and geophysics of guyots and about the composition and distribution of ferromanganese crusts.
43-55 669
Abstract
In terms of detail landscape-morphological mapping, a series of observing maps of Anapa sand bar was compiled, including maps of morphometric characteristics of sand bar (wideness of beach, dune belt and hillock sands, height of dunes), wind exposition of shore, aeolian processes, anthropogenic impact. The maps show essential differences in morphological structure of sand bar caused by natural and anthropogenic factors. At the northern edge of sand bar, where wind exposition is 90°, builder areas are disposed at some distance from sand bar beach reach 100–130 m. Beach, dune belt and hillock sands are wide, dunes height is 10 m at long extend, and so sand bar has reached some dynamic equilibrium. At more southern region, where wind exposition is 80°, builder areas of Vityazevo and Northern Jemete settlements have come just to sand bar. Strong anthropogenic impact, walking on dune’s surface caused degradation of vegetation and intensification of aeolian processes, forming of sand trains. Height of dunes grows to 12–13 m due to implantation of trees at hillock sands. At central part of region buildings of Jemete settlement have come into coastal zone. Beach and dune belt decreased to 30–50 m everyone, dunes transformed to bush fixed hillocks, divided by bare sands. Some remains of dunes are very high (18 m). At the south of Jemete, recreation area of Northern Anapa has come to dune belt. Under reducing of wind exposition to 60° and decreasing of beach to 50–70 m, dune belt is widen to 100–130 m and series of 2–3 ramparts of 7–8 m in high are formed instead of one. Buildings rapidly move into dune belt, destroying ramparts, and hollows with hillock sands are used for waste storing. At the edge of southern part of region, near Anapa, wind exposition reduces to 40–50°; dune belt decreases to 50 m and has one rampart of 3–4 m in high, and with reducing of wind exposition to 30° disappearing at whole. These differences in morphological structure and statement of sand bar must be taken into account in land use planning and in decision-making for sand bar conservation and defense.
56-69 687
Abstract
On the sides of volcanoes the chain of paragenetic processes performs from the top and to the foot that includes volcanic, slope mass movement and erosion processes. River valleys provide transportation routes (“transport corridors”) for sediments involved in the lithodynamic system. Valleys are used by pyroclastic flows that transfer much volumes of sediments. Fluvial processes transport them from the upper parts to the foots of volcanoes. Physical properties of volcanic materials predetermine specific features of its reworking by water flows and thus exert influence on fluvial processes in river valleys. In the bottoms of river valleys, not alluvial but debris flow, mass movement, aeolian, thermokarstic processes dominate throughout the most part of year. Development of glaciation contributes to the increase of non-uniformity (“salvo” character) of lithodynamic flows and increase the area of pyroclastic material reworking by fluvial processes.
70-77 877
Abstract
The variety of morphological features and physiographic differences of sea coasts in European Russia is described from arctic deserts and tundra on the Barents Sea coasts to the Submediterranean landscapes, semi-deserts and deserts in the coasts of the Caspian and Black Seas, as well as differences in economical development of the coasts. The problems of forecasting of sea shore development are discussed: the general approach to forecasting; set of necessary maps to make; direction and amplitude of sea-level changes over the period of interest. The scenario approach is substantiated that answers the question – how will the coast develop under different changes of sea level and climate conditions. Morphogenetic types of the sea coasts and the legend of sea coast morphogenetic map are described as the basis for further researches.

History of Science

78-85 1498
Abstract
A.F. Middendorf opened a new age of Russian geographic discoveries by his vouages to the Far East (1842– 1845), to the Baraba steppe (1869) and to the Middle Asia (1878). Some prominent scientific works have issued from his pen: “Travel to the North and East of Siberia” (1860), “Baraba” (1871) and “Sketches of the Fergana Valley” (1886). During his travels he made significant contribution to geography and geomorphology. After the Siberian expedition Russian scientists got a real insight into the orography of large regions of the Eastern Siberia and Far East. He discovered the Putorana plateau, he was the first to explore the Stanovoy range, the North-Siberian lowland, Amur region. He studied large Siberian rivers; clarified the morphology of the Okhotsk Sea southern coast and the Shantarskiye islands; made the Amur region’s nature sketch and map; layed the foundation of modern ideas about permafrost distribution. He found out that the Russian-Chinese border passes along the Stanovoy range slope, thus adding to the Russian territory some 50–60 thousands of quarter kilometers. This was helpful for solution of the question of the Amur region and Far East joining to Russia. During expedition to the Baraba steppe the scientist made interesting assumtions concerning the marine genesis of the Baraba, its relief and sand spits. During expedition to the Fergana hollow he was the first to define the role of Fergana’s morphostructural isolation in conservation of its natural and economic wealth; he contributed a lot to studying the deserts relief and was the first to propose the Fergana’s deserts classification; he fixed that Fergana is the ancient region of human settlement.

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ISSN 2949-1789 (Print)
ISSN 2949-1797 (Online)