Articles
There are several alternative tectonic models of the Far East mountains origin: geosynclinal folding, lineamentblock neotectonic uprise, tectono-magmatic activation, tectonic and morphogenetic processes connected with local magmatic centers, horst-accretional and graben-rift tectonics, terrain or plume tectonics. By authors’ opinion the main features of morphostructure pattern of orogenes (deep “roots”, sub-parallel location, translational distribution of large watershed junctions, etc.) may be reasonably explained only on the basis of plume tectonics and of morphogenetic processes connected with magmatic centers. The structural frame of the orogenic belts territory is formed by linear systems of arch-block and tectonic-magmatic uplifts. Their origin and development are conditioned by periodic activation and general evolution of the Circum-Pacific deep faults of the East-Asian overplume mega-arch and its satellite magmatic centers during the sustainable Late Mesozoic-Early Cenozoic eastward migration of the front of acid magmatism and westward migration of the front of the mafic one.
The paper is devoted to 85th anniversary of D.A. Timofeyev. The ways of development of the theoretic concepts about evolutionary and exogenous (climatic) geomorphology, about morphosculpture and morpholithosystems are described. The structure of the morphosculpture analysis is suggested as one of the ways leading to “synthetic geomorphology” – analysis of outer connections, inner relations, stability of morpholithosystems, their typification by level and degree of organization. More closely are considered some types of the morpholithosystems stability: quietude, development, equilibrium, anthropogenic and self-destruction.
Sedimentary structure in a delta-like area of the man-made lake basin, in the coastal transitional zone of wavedominated and fluvial-dominated environments, and at the coasts with normal development of reservoirs where wind-induced waves are the key driving factor were thoroughly studied and described for the first time.
Ecological and Applied Geomorphology
Theoretical and methodological questions of ecogeomorphological mapping as well as the main definitions of notions were examined.
The lack of elaboration of the theoretical and methodological base and the definitions didn’t hamper the creation of plenty of ecogeomophological maps which are at the second place in the top list of all ecogeographical maps by quantity (after pollution maps) along with anthropogenic transformation of geosystems maps. Mass creation of such maps is determined by the demand from practical issues such as engineering and environmental survey, search for ecological emergency zones, environmental impact assessment etc.
Facet system of classification for ecogeomorphological maps, which lets us systematize already created maps and to optimize the new ones, was proposed. At the first level 8 main criteria were proposed: thematic, mapping level, actuality of information, principals and basis for localization of thematic content, approaches, synthesis level, consumers, location.
According to thematic the following categories of maps were proposed: anthropological impact and its consequences, geomorphological dangers, geomorphological risks, geomorphological situations, geomorphological sustainability, negative impact recipients, geomorphological aspects of living conditions, nature and ecological potential and so on.
Scientific Research Methods
In recent years artificial beaches are often used for coastal protection of seas and man-made lakes. Volume of nourishment depends on the shape and the length of the equilibrium beach profile. When solving a wide range of tasks different methods for equilibrium beach profile calculation are used. In this paper we make an attempt of reliability assessment of some methods currently used for calculation. We compared the natural beach profile with equilibrium beach profile calculated by different methods. Three approaches were used to calculate the shape of equilibrium beach profile: the Bruun-Dean formula, the method prescribed by Coastal Structure Construction Code, and numerical modeling by SBEACH. To obtain the source information an artificial beach at the Novosibirsk Reservoir, Russia, was chosen. This beach was constructed in 1959-1962, and replenished 25 years later. The morphometric characteristics of the beach are still almost unchanged. This allowed us to conclude that the beach profile is in equilibrium.
The analysis shows that the equilibrium profile calculated by Dean’s formula gives the best agreement with the data. That is of theoretical and practice interest. It should be noted the method originally developed for the ocean coasts works well at man-made lakes. The work was supported by RFBR (projects 11-05-00615-а and 11-05-10046-к) and federal target program “Research and development on priority directions of scientific-technological complex of Russia in 2007-2013”(project 16.515.11.5075).
The author suggests an approach to automatic geomorphological zoning by relief types. The method is based on a combination of standard techniques of grid analysis (software package ArсGIS 9.3) and pattern recognition methods (supervised classification) widely used for processing multispectral satellite images (software package ENVI 4.5). The initial data are morphometric characteristics obtained from SRTM by means of moving average. There are two alternative ways of morpho-complexes schemes compiling. In the first case discrete landforms are derived by morphometric parameters, and morpho-complexes are then delineated by their areas ratio in a moving window. In another case, the morphometric parameters are loaded into the software ENVI 4.5 as channels, where supervised classification is performed. The sites which are definitely diagnosed by their historical and genetic aspects serve as a model area. The resulting morpho-complex schemes show a good agreement. The proposed approach is easy to learn. It also significantly reduces the complexity and routine work duration in geomorphologic mapping.
Short communications
The geological and geophysical materials on distribution of the glaciations and sea transgressions that occurred in the last 140 thousand years have been analyzed considering glacio-eustatic transgressions and position of the Ocean level. While the glaciation degraded and the rise of the continent was less than the rise of the sea level, transgressions took place. The most probable areas of glaciation distribution during marine isotope stages (MIS) and sub-stages 6, 5b, d, 4, 2 have been reconstructed. It is shown that the sea transgressions related to glaciations took place in MIS 5e, d, 2 and 1.
The problem of the detecting of horizontal component of neotectonic motions is being investigated on the base of comparison of morphostructure of the region near boundary of the East-European and West-Arctic platforms and structural pattern of the fracture of separation. In the region of the margin part of the East-European platform one can see large Pribelomorian depression of lens shape. Because we could not explain it origin only by erosion, we can consider it to be of neotectonic predetermination. It’s surrounds by uplifted during neotectonic period parts of the platform. The part of this margin between Pribelomorian depression and West-Arctic platform is forming the curve belt, conformal to the margin of the depression and bends as the ledge in less consolidated rocks of the West-Arctic platform. In front of the ledge in this platform, one can see the uplifts, that can be consider as the evidence of compression in the front of indenter. Near the opposite (Karelian) part of the depression one can see similar and symmetrical situation, that expressed by the difference in lake distribution.
The boundary of the depression, uplifts, discontinuities between basements of different rigidity, are underline by tectonic zones, shapes in relief.
The distribution of morphostrucrures can be associated with the structural pattern of the large fracture of separation (zone of extension), producing by horizontal motions of borders. Possibly it develops in inherit way. The compressional fields with main axe extended along depression, are well known by independent methods. The natural situation is illustrates by modeling with clay.
On the Olkhon Island we distinguished three genetic types of the shores: structural-abrasion, abrasion and accumulative ones. According to the dominating exogenous process these types were subdivided into abrasionlandslide, abrasion-fall; abrasion-aeolian and biogenic subtypes. Quantitative measurements of the shore length showed that the total shore length of the Olkhon Island including lake-like lagoons constitutes 225 km. Of the total length abrasion shores consist the 68% (153 km), structural-abrasion shores – 25.3% (57 km), and accumulative ones – 6.7% (15 km).
On the coasts of water basins floodplain-terrace complex there are many exogenous processes of apparent minor significance which however have obvious impact on the coastal landforms. For almost half of the shore-line they are the single cause of the shore morphology changes. For instance on the surface of the shallows the deep (up to 40 cm) cracks appear, which are permanently widening due to inflation. The peat island had been anchored near the bay at the Visim village (the left bank of the widest part of the Kama water reservoir) and blocked the drift of deposits which caused the widening of the beach and terrace appearance. The tube erosion in the detached and sunk blocks, landslides and earth-falls leaned against the cliff. Diameter of the tubes reaches 1.5 m at the mouth, their length – more than 4 m. The most density of the erosion tubes (10–15 / 100 m) occurs at abrasion-earth-fall and abrasion-landslide types of the bank consisting of deluvial loam. Deflation may remove from the slope 5–7 cm of sand under the conditions of dry and windy weather during 3–5 days.
The review of field investigations and simulation results led to the conclusion that efficiency of groins use depends on two main factors: amount of free sediments on the bottom slope and angle of wave approach to the shore. The positive effect of groins use can be achieved when angle of approach is acute and sufficient amount of free material is available. Groins are not effective without additional supply of loose sediments if waves have nearly normal approach to shore and there is a deficit of free sediments. An increase of effectiveness of groins could be obtained by varying of their length, spatial step, and orientation. A reduction of downstream erosion is achieved by shortening the groins and adjustment of their complex to the shoreline contour, beach nourishment at the downstream areas, and using of permeable (30–50%) groins.
A series of longitudinal profiles of coastal slope of Southern and Western Crimea have been compiled and analyzed. It revealed the ancient coastlines. Their age have been determined by the regional curves of sea level change. Ancient coastlines helped us to calculate rates of abrasion during last 18 thousand years as well as during all upper and middle Pleistocene. They have been compared with the present real and potential rates of abrasion. In most cases current rates are smaller, however there are some exceptions. The comparison of underwater coastal slope profiles and the rates of abrasion in the Western and Southern Crimea have been made. The rates at the Southern Coast are several times smaller than at the Western Coast.
During circumpolar distribution of the large rivers with large streamflow the wide floodplains with high amplitude relief were formed in their valleys. While the discharge of the river diminished this relief was partly reformed in the course of the lateral reformations of the river channel and ancient floodplains on the large areas took on inherited character. Due to their wideness inherited floodplains serve as a effective barriers between the erosion part of the river system (erosion furrows on the slopes and gullies) and balka-river part where transit and accumulation of the sediments by the most part take place. The most part of the sediments from gullies and slopes accumulates on the inherited floodplain. In the result there is very low correlation of sediment transport regimes even between close ranges of the river. Dating of the sediments proves that as largest basins on the floodplain are being infilled and the level of the floodplain rises, the rate of accumulation and barrier effect diminish. At last the inherited floodplain relief changes totally due to lateral and vertical river bed deformations and sediment transport in this river range is being retrieved.
History of Science
A.A. Borzov was true field surveyor who had studied much of the European Russia as geomorphologist and physical geographer. During the first part of XX century this territory was researched only by Russian scientists, and foreign scientists largely didn’t know about it. Borzov focused on erosion relief of humid plains, moraine landscapes and also theory and practice of mapping. He devoted his special works to improvement the normal (erosion) cycle of V. Davis. He wrote some additions to Davis doctrine, the major is: erosion on plains leads to asymmetrical interfluvial relief structure, and asymmetrical cross section the more expressed the more upward interfluvial development stage is. Asymmetrical cross sections of interfluvial areas and deluvial coats on their shallow slopes certainly should be developed on specific stage of its development depending on amount of geographical factors.
Anniversaries
Joint authors of the Scientific Research Laboratory of Soil Erosion and Channel Processes named after Makkaveyev, Geomorphological Department of the Institute of Geography RAS, MSU Interacademic Coordinating Research Council on Erosion, Channel and Estuarial Processes and Editorial Boarding of Geomorphology RAS Journal congratulate one of the most major scientist in erosiovedenie with 75th anniversary and list short bibliographical background about L.F. Litvin.
Reviews
Present paper states the review to the second collection of works “Geomorphologists. New Generation” published in 2013 in Media-PRESS under editorship of Kladovshchikova M. and Likhacheva E. It consists of eight articles of young scientists – PhD fellows, PhD candidates and doctorates, and reflects wide spectrum of scientific issue
Present paper states the review to V.A. Smirnov monograph “Hot karst: volcanic holes in carbonate rocks of the Urals”, where actual data of ten years of complex caves study in the central part of the Perm Ural Region is generalized.
Obituaries
ISSN 2949-1797 (Online)