The «egeomorphic levels» (first introduced by K. K. Markov) cannot be considered a reliable indicator of the endogenic-exogenic processes interaction in the relief formation. The leveled mountains summits («the upper level of denudation») often do not indicate equilibrium between the endogenic input of the material and its removal by erosion. The summit level comes into being because of limited energy of the uplift and load beyond the strength of solid rocks in the mountains base and also because of deep layers being fluidized and spread under the load of the whole mountain formation. The authors think it more reasonable to replace the term upper level of denudation» with some other, which does not imply its genesis (such as «Summit level» etc.)

The paper summarizes data on exogenic morpholithodynamics of the seasonally wet tropics in Africa. Relations are traced between micro- and mesorelief evolution, surficial formations and landscape features. The importance of various factors in the morpholithodynamics is analyzed, including the human impact. Principal models of relief and loose mantle evolution are described, which are characteristics of the seasonally wet tropics.

Генезис рельефа

Размышления о размышлениях Г. Ф. Уфимцева

A rather widespread notion is that the Earth surface relief is «material» object of the geomorphology having however «no substance». The author insists that such an idea is wrong and should be abandoned.

The paper deals with assessment of gully erosion probability due to human impact on natural complexes. A new methodical approach is developed which is based on calculated ratios including a number of natural characteristics which control the rate of linear erosion; threshold values of gullies density and frequency have been calculated and maps are composed which show potential development of gullies within the limits of the Russian Plain. The paper is illustrated with a fragment of such a map (scale 1:2-5 mln) showing the utmost in potential gullies density in some central regions of the plain.

The paper discusses possibilities to identify some natural hazards from images on topographic maps and aerial photoes. Particular meso- and micro-Iandforms produce characteristic pattern which indicate such phenomena as potential subsidence in loess, sheet and rill erosion, salinization of soils, suffusion, karst and some others. Some quantitative characteristics of dangerous processes which are important from the practical point of view may be obtained on the basis of the found functional relationships between quantitative indices of landscape pattern and the geodynamic conditions of key sites.

Various kinds of mudflows are described within the Baikal region and in the Baikal Lake, which form a single series from incipient mudflows to degrading ones, transitional to other types of sediment transport and including elements of two (more seldom, three) different processes. Concrete examples of those different types of mudflows are described in detail, prerequisites of their formation and disastrous results are considered. The approach to mudflows classification may be used in other regions.

Small rivers prevail in the drainage network and control the state of environments within the region to a considerable degree. The authors' studies over the Udmurtian territory revealed silting of small rivers channels and floodplains which resulted from violation of natural course of fluvial erosion and alluviation due to deforestation and land cultivation. The authors emphasize the necessity of the small rivers conservation which is most important ecological problem in the region.

The Spitak morphostructural node is formed by two lineaments intersection: the Pambak-Sevan longitudinal and Transcaucasian transversal ones. Both vertical and tangential neotectonic movements are recorded within the Pambak-Sevan zone. The nodal area is distinguished by most differentiated topography of ridges and basins formed within the region of large lineaments intersection. Isoseists of the Spitak earthquake outline the nodal area. The earthquake location is connected with a previously existed fault which was not however the most active one. Some traces of older earthquakes are found within the region. The region does not form a landscape unity, as it lies at the boundary of different physical-geographical regions and includes various elements.

Some results of structural-geomorphological studies are presented which incduded drainage pattern and the present-day slopes in the Terek-Sulak depression. Computers are shown to be widely used for the morphometric analysis.

The studies provided new data on details of the deep structure of the area, revealed new structures and ascertained the degree of their neotectonic activity, which is of interest both for theoretical considerations and practical application to searches for oil and gas.

Urban areas are subdivided into regions on the basis of spatial differentiation of hydrological processes and associated soil loss. The primary material for the quantitative (including statistic) analysis of the processes comes from experimental studies Io the city of Kursk. Principles of regionalisation and quantitative characteristics of runoff and soil loss within the regions permit physical model ling and forecast of runoff and erosion quantities within urban territories.

About 2384 m³ (or 4990 tons) are yearly removed from the Voron River drainage basin (15.73 km²), situated within the Upper Jurassic conglomerate zone. A considerable volume of solid runoff and small mudflows are known only from those gullies and valleys of the 3--4 order which cut relatively weak varieties of conglomerates and brecchias, their slopes are 28 to 90^o steep.

The paper discusses regular features and the mechanism of transformations of valley diamond placers in the process of their burial under alluvium under conditions of rhythmical ingressions and erosion within the valleys at the marginal parts of the Tungus and Vilyui syneclises. The necessity is shown to study both buried landform morphology and the structure of covering series, the data thus ontained provide the basis for paleogeographical (and first of all paleogeomorphological and paleohydrological) reconstructions, they indicate directions for further searches. The authors attribute a considerable importance to paleohydrogical regime as a factor which controls the landforms development, transformation and destruction in the process of the placers formation.

The lichenometric investigations on Broze Age stone graves about 1000 and 2500 years old were carried out in Jasator valley (Yuzhno-Chuisky Ridge, Altai). 71 archeological sites were investigated and the growth rates of lichens Lecanora bicincta, Aspicilia sp., Rhizocarpon geographicum, Parmelia taractica + P. separate were determined. These data allowed to estimate the age of the surface of a rock glacier in the same valley.

Methods developed by the authors were applied to reconstruct the Late Paleozoic buried topography on the eastern flank of the Tungus syneclise (where two diamond regions of Western Yakutia are located: MaloBotuobinsky and Morkokinsky). Principal types of tectonic distortions are identified which changed the primary appearance of the Late Paleozoic surface. The compilation of maps of reconstructed topography is a stage in the course of search and prospecting for diamonds in covered regions.

Stationary observations of the coastal zone morphology and dynamics are carried out on 11 sites near the Cape of Burnas (the Black Sea). Both erosional and built-up landforms above and below sea level had been surveyed each year since 1967 to 1989. The data thus obtained, together with older topographic maps (dated to 1863 and later) permitted to determine that the clayey cliff retreated 1.6 to 3.1 m per year. Similar rate show a nearby sandy and Shelly beach-barriers of the Burnas and Budaky limens. In particular year the cliff edge may collapse and retreat by 18-19 m. Maximum rate of retreat averaged over the whole redion is 7.35 m per year. The recent dynamics of the coastal zone is appraised by means of a dynamic coefficient, where it exceeds 1 the shoreline is stable and the beach accretion takes place. The sediments characteristics within the studied sector of the coast indicate the prevailing longshore drift towards south-west.

Вклад Н. А. Соколова в развитие учения о морских берегах

26-28 декабря 1991 г. в Московском государственном университете состоялась научная конференция «Эрозиоведение: теория, эксперимент, практика». В работе конференции приняли участие 119 представителей 43 учебных, научно-исследовательских и проектных организаций шести государств СНГ и Литвы.