Articles
Analysis of data on relief and geological structure of the continental part of the Dagestan coast of the Caspian Sea, and especially, aging of sediments of marine terraces by faunal data (shells) confi rm the existence of the independent Girkan stage of the sea development. Girkan transgression occurred in the time interval between Late Khazar and Early Khvalyn transgressions. As a result of the abrasion activity of Girkan transgression the topography of the coastal lowland and its morphological boundary with the foothills of the Greater Caucasus were fi nally formed. The boundary has an altitude of 100–105 m and 120–130 m. These altitudinal differences arose as a result of tectonic movements and accumulation of slope and alluvial-proluvial sediments at the foot of the escarpment separating the coastal plain from foothills. The Late Khazar and Girkan transgressions occurred in different climatic conditions: fi rst, in the era of MIS-5e (interglacial), second in MIS 5d-5a with repeated alternations of warming and cooling.
The article provides rationalization for distinguishing special forms of the channel topography – point bars – representing an united aggregate of ridge-type macroforms of channel topography – parts of banks, bars, midstream sandbanks, which are drying during low water. They occupy an intermediate position between the lowflow channel and fl oodplain, both as a part of the channel and participating in its reformations and as initial element of the evolving fl oodplain. At high water levels they are in the subaqueous environment under the infl uence of the fl ow. With decreasing levels, they have a growing infl uence on the course of fl uvial processes, causing seasonal reorganization of the channel. At low water they represent the elements of land and being in subaerial conditions are exposed to wind and rain; they are also overgrown with vegetation. In the end, point bars over time become young fl ood plain. At the Upper Ob’ their stabilization due to the overgrowth takes from 12 to 25–30 years; on the Northern Dvina turning of the midstream sandbank into fl ood plain island with a height of 5 m takes about 100 years. Over the past few decades in almost all rivers of Russia an increased growth of riparian fl ats is witnessed, which is associated with fl ow regulation of rivers and their natural cutting-in.
Short communications
The Ufa “Peninsular” since active development is experiencing a shortage of land resources due to intensive dissection of Perm massive, on which the city is situated due to constant expansion of the latter. Structuralgeomorphological analysis, using remote sensing materials, field investigations, and drilling data have shown that Permian gypsum, limestone and sandy-clay rocks composing the territory, are divided by vertical and horizontal crustal deformations into blocks of different sizes. As a result, the rock mass was deconsolidated, which caused the
intensifi cation of the formation of ravines and landslides.
Based on digital elevation model the geomorphological zoning of the Belomor-Kuloy (White-Sea-Kuloy) plateau (northern part of the East European plain) was carried out. The territory of the plateau was divided into 7 geomorphological units. The paper presents new data on the geomorphological and morphostructural features of the territory. Maps compiled are the most detailed at present that distinguishes this work from previous ones. Comprehensive analysis of the various cartographic materials and DEM identifi ed a number of cross-cutting parageneses in the system of crystalline basement, sedimentary cover and modern relief. It is shown that the boundaries of geomorphological units are controlled by faults in the basement. Thus, the tectonics of the region has a signifi cantinfl uence on the topography of the plateau.
The infl uence of the microrelief of arable land on the intensity of soil erosion, caused by melted snow waters was considered on an example of key area “Luchanovo” (20 km south-east of the Tomsk city), where gray forest soils are involved in arable land cultivation. The study of soil erosion in the period 1988–2013 showed that on the slopes of the arable land having the steepness up to 17° a complex microrelief was formed. It is represented by microbasins of hollows and water galls, depressions on the watersheds where the snowmelt runoff takes place. The value of soil loss from the surface of microbasins even on the one and the same slope depends on its area, steepness, length, snow melting, etc., and varies from 0.5–2 m3/ha to 81 m3/ha, predominantly having the value about 50 m3/ha. During 23 years the thickness of the humus horizon on the fl at interfl uves has decreased by 3–6 cm, humus content – by 1.03%. The annual lost of the humus from the slopes with arable land reaches 0.6–1.7 t/ha leading to degradation of soils.
The principles of seashores mapping are worked out and classifi cation of coastal types is carried out. A Map of the Crimean coastal types is compiled, in the scale of 1:500000. While compiling the map, the coast length of each type was measured and their spatial relations were described. The results show that for the Crimea on the whole the most characteristic coasts are the erosion ones (25%), to a slightly lesser extent – erosion-accretion (18%) and lagoon (15.7%) coasts. However, each part of the Crimea coasts due to its geological and geographical features, has a specifi c “set” of shore types: the western coast is dominated by accretion shores (beach and lagoon ones – 40.7%), on the south coast – erosion-landslide shores (27.8%), on the east coast – typical erosion shores (45.7%), and on the Sivash coast –accretion-erosion (40%) shores and mud fl ats (23%) are predominated.
Isometric shape of the lake Rabiga-Kul, the ratio of its diameter and depth, the presence of the surrounding rim, the discoveries of cosmic matter in Quaternary sediments testify in favor of the impact origin of the lake basin on the border of the Pleistocene and Holocene. By means of microprobe analysis the microparticles of a size up to 20 nm were found. They consist of the native metals: iron, Nickel, tungsten, zinc; microspheres of magnetite, wustite, troilit, intermetallics, similar to those occured at the well-known astroblemes on the Earth were found. The minerals of technogenic (?) origin, are also present, the formation of which may be associated with the metallurgical production of the XI–XIII centuries around the ancient city Bolgar.
In the steppe zone (The Ural river basin) rounded river openings occur. These openings have signifi cant (up to 5 m) depth, occur too often and are distributed chaotically. So it is unlikely they are the remains of the former pools of the river. They are found in silted riverbeds, and in dry oxbow depressions of the incutting rivers; they are characteristic to flatter sections of their longitudinal profi le. The analysis of the morphology and distribution of the lake-like extensions allowed to put forward the hypothesis of a signifi cant role of suffusion an karst processes in their formation, aggravated by the extinction of the channels. The favorable condition for such forms generation are the reduction of water and sediment runoff. In the rivers with constant flow sink holes are quickly infi lling with alluvium.
In the valley of Imangda river (western part of Putorana Plateau) four multiple-aged moraine complexes were identifi ed. Three of them are correlated with the known stages of deglaciation of the Late Pleistocene glaciation in the north-west of Siberia: karaulskaya stage (25–17 ky BP), nyapanskaya stage (15–13 ky BP) and norilsk stage (11.5–10.4 ky BP). Moraines of these stages vary in degree of preservation, roundness of coarse material and the extent of their areal. In the Late Pleistocene and Holocene the glaciation of this territory had cirque and mountainvalley nature. There was no solid ice cover over the plateau. However, isolated ice caps with outlet glaciers could exist in some parts of the plateau. The fourth, younger moraine was formed during the Little Ice Age. Glaciers then do not go beyond the cirques.
History of Science
Leader of the geomorphological education and an outstanding, different-sided scientist, Professor of Moscow State University academician K.K. Markov has made a signifi cant contribution to the development of physical geography, paleogeography, Quaternary Geology, geomorphology, geography of the World ocean. We briefl y
described two of the fi rst monographs of K.K. Markov, “The main problems of geomorphology” and “Paleogeography” and forgotten, but serious and important course of lectures on military geography read in 1941–1945, in which he stressed the ideas of Russian military geographers P. Yazykov and D. Milyutin. Some attention is paid to the main ideas of a little known works by K.K. Markov on arid geomorphology: “Problems of paleogeography of Morocco”, “History of the Dead Sea” and “The History of the Lake Chad”. In conclusion, the article provides an example of solving by K.K. Markov some fundamental problems of the origin of mountain denudation surfaces. The scientist reasoned the existence of one, at least two planation surfaces, he has shown that the hypsometric characteristics of the levels must be supported by age dating; considered the age of the surfaces to be Alpine and pre-Alpine; identifi ed two types of peneplain: primary – low levels in the platform areas and relict, palaeotype raised levels in the mountains.
Anniversaries
Reviews
Chronicle
On 17–21 August 2015 in Moscow was held the regional conference of the international geographical Union “Geography, culture and society for the future of our Earth”, which was attended by more than 2000 scientists. The main themes of the conference – city environment, researches in the polar regions, climate change, global confl icts and sustainable development of the regions. Our attention is focused on the reports of geomorphologists and on the aspects of those commissions that are most closely linked to the evolution of the relief, the activity of relief formation processes, modern methods of researches, including mapping.
Obituaries
Information
ISSN 2949-1797 (Online)