The Alabuga valley structure in the Central Tier-Shan indicates unusual downcutting rate, too high even for mountain streams. Usind various methods (historico-archeological, dendrochronological, cartographic, hydrological, dating by measuring the desert varnish thickness) the present-day rate of downcutting has been estimated, as well as its variations during the last 1300 years. The river channel cut through the Late Quaternary cemented gravel about 20 to 50 meters thick, the downcutting rate being about 0,5 cm per year. Having reached underlying lacustrine silts (Neogene) which are less resistant to erosion, the rate of deepening increased up to 9 in per year and more. Mean annual values of channel downcutting are about 0,4 to 0,9 cm near the river mouth and reach 32 cm near the Djergital water intake.

Such rapid deepening interferes considerably in normal operation of water intake stations and bridges. The authors come to the conclusion that in mountains the channel deepening reaches catastrophic rates under conditions of channel load deficiency and weak bedrocks. It morphological evidences of rapid downcutting are discerned, fluvial dynamics should be studied in detail before ehgineering works.

Running water is foremost among exogenic factors. The geomorphology usually deals with integral result of its activity averaged over some geological time intervals, thus assuming strictly progressive evolution of fluvial relief. Streams have a special kind of internal mechanics which have an effect on the process under any external f actors. Considering volume of matter involved and impact on topography, streams are on a par with endogenic forces and often excel the latter in results. Due to permanency of internal f actors and their inherent contradictions the relief occasionally comes to the states of so-called «self-regulation», «spontaneous development», «self-excitation» in the process of its evolution. Consequently the relief undergoes a complicate reciprocating evolution, it lives, functions and changes like a living organism.

Solutions of diffusion equations which describe pattern of the relief evolution have been analysed and an ambiguity is shown to be present in the basic definitions of the enthropy and time direction in geomorphic processes. To exclude the ambiguity it is suggested to deduce the enthropy of geomorphic systems from their hypsographic functions (i. e. functions of height distribution). When concerning the real evolution of the relief with many states of equilibrium and non-equilibrium, possibilities of the process description using diffusion equations are shown to be limited. The necessity is emphasized to use more complex mathematical technique of the dymanic systems theory.

Regarding the monograph ,,Morphodynamic analysis" by A. N. Lastochkin (Leningrad, Fredra Publishing House, 1987) the author indicates that the elementarization of the Earth's surf ace may proceed by use of morphological Criterion: point, linear and areal elements are identified as limiting landforms of various order. Genetically homogenous surf aces are also classified among elements by some authors, it should be remembered however that the notion of «genetic homogenous surf ace» is taxonomic in itself, and may refer not only to elements, but also to landforms and their groups. Morphological criteria permit to discern a certain sequence of geomorphological objects which is as follows: topographic element — landform — assemblage of landforms of various order. This morphological sequence corresponds to genetic series of the same components which present in themselves variants of homogenous surf aces differing in taxonomic order.

A special symbolic language is introduced to be used for description of geometric characteristics of point, linear, areal and three-dimensional topographic elements in the geomorphological mapping. The language is based On linear recording of words composed of letters of a certain alphabet according to the rules formulated in the article, the system of recording resembles that used in algorithmic languages.

Элементаризация рельефа и язык его геометрии - ответ оппонентам

A special symbolic language is introduced to be used for description of geometric characteristics of point, linear, areal and three-dimensional topographic elements in the geomorphological mapping. The language is based on linear recording of words composed of letters of a certain alphabet according to the rules formulated in the article, the system of recording resembles that used in algorithmic languages.

The paper deals with extrapolation method as applied to channel processes forecasting, to shallows reformation under conditions of both restricted and free development of channel deformations in particular (case study of the lower and middle Vilyui). The method can be applied only on the condition of steady state of the system (i. e. constancy of controlling f actors), the forecast is limited to a few decades. Three trends are distinguished in the channel shallows evolution: flow concentration and deepening, flow diffusion and decrease in depth, relative stability of the channel's depth. Possibilities are discussed of artificial reversal of trends unfavourable for navigation. In the author's opinion, it is economically justified t o establish priorities for channel regulation: first, channel's reaches with shallowing in progress, then constantly shallow ones and finally, those where conditions are changing for better. The forecast of shallows development given in 1977-1980 is assessed on the basis of channel observations during 1981-86, the error of forecast appeared to be 10%.

The density of valley and gully network controls to a considerable extent slopes length, steepness and profile and therefore soil erosion. Inadequate agricultural technique constantly used under conditions of deeply dissected topography resulted in enhancement of erosion processes. Gullies and eroded soils form components of agricultural lanscaped of Kursk region and impart an ecological stress to the landscapes. The productivity of agricultural landscapes is low within the zones of high ecological stress.

In Moldavia the sedimentary upper horizon of Cenozoic is usually displaced along fault-lines of SW and SE direction. Tectonic impulse at the platform's margin coicided with the 3rd Late Pliocene stage of large charriage formation in the Carpathians; it caused many normal and strikeslip faults and overthrusts with gently sloping thrust plane. Most landslides are restricted to those tectonic zones. Clusters of landslides are also found within mobile tectonic zones which had been delimited during the mapping of a paleogeographic marker surface - the planation surf ace dated from the Middle Pliocene. A few landslides are older than the Late Pliestocene - Holocene, they were probably formed along fault-lines due to earthquakes or on slope due to erosion of its base.

A comparison of the Baltic Sea bottom morphology to the tectonic and geological structure is used as a basis for condideration of large landforms genesis and endogenic processes importance to the bottom relief formation. Morphostructures development since the Mesozoic to the Holocene is analysed for the Baltic region.

During the 8th voyage of R/V «Vityaz» a detail echo-sounding has been fulfilled within a test area (60х105 km) in the central part of the Danube alluvial an (NW Blaсk Sea); total length of sounding profiles exceeds 1700 km. Data processing, analysis and interpretation resulted in construction of composite profiles of sea floor topography, bathymetric and geomorphological schemes. A physiographic block-diagram of the studied part of the fan was constructed on the basis of the depth cadastre and a digital model of the sea floor topography using the computer ES-1035. The area corresponds to an active fault zone. The paper describes in detail the morphology of the largest sedimentary body in the Black Sea. Some conclusion are drawn on the fans formation and development.

For the Terek-Kuma Lowland the wind regime is proved to affect considerably the recent eolian landscape, the largest eolian landforms orientation is however tectonically controlled. The author discusses a possibility to estimate the present-day activity of structural forms by way of studies of eolian relief. The results may be applied to searches for oil and gas.

Deltas of Pur, Taz and Messoyakhi .rivers were formed during the Late Pleistoce.ne .and Holocene under conditions .of reduced river discharge (by factor of 1,1 to l,8) and solid runoff (by factor .of 3 to 4), rising oceanic level and active differentiated tectonic .uplift .of .the area (up to 112 mm per year). Geomorphological mapping .of low terraces and fIoodplain levels together with radiocarbon dating of the sediments permit to reconstruct main stages of the deltas relief formation in the process of .infilling of narrow ingression bay.

Studies of numerous sections in the loess on watersheds in the Taj'ik Depression revealed the eolian sedimentation to have been the main process in the loess formation, Loess post analysis permits to various elements of buried topography. A variation surface is identified which had been formed at the end GE the Eopleistocene. lt serves now as an important geomorphological marker, its distortions provide information on direction and rate of tectonic Movements during Pleistocene.

Two sites in the Inner Tien-Shan are discussed in detail, one is in a small valley at the southern flank of the Jetim-Bel Ridge (4140 to 3850 m a. s. L), the other at the southern slope of the Ah-Shiirak Ridge (4070 to 3860 in a. s. l.). The author describes structure of slope surface and loose mantle and speculates on the slope evolution and mechanism of the slope processes.

The drainage network within the region- is largely controlled by general structural pattern. The riftogenesis preconditioned two types of river valleys, which are trunk valleys and «feather» valleys. Trunk valleys drain riot depressions, the drainage boasins show a typical asymmetry of Baikalian type, left and right sides of a basin differing in and in tributaries structure. The trunk valleys evolution proceeds against the inherited subsidence of the basins floor. Morphometric analysis permits to outline individual blocks of the basement and to establish their relative altimetric position. «Feather» valleys develop under conditions of differentiated movements of crustal blocks. Rivers of this kind also show differences depending on their position with respect to the rift zone axis, which indicates some differences in the geomorphic evolution of the areas.

Изучение погребенного рельефа для поисков нефти и газа

Маккавеевские чтения

Вторая международная геоморфологическая конференция

В. П. Зенкович — основатель советской школы геоморфологии морских берегов