The author uses the system - approach to analyze some privation and erosional landforms. Structures of the feedbacks are described which control the self-organization of natural systems (i. e. increase in regularity and decrease in variability-entropy). In the case of the privation cirques the self-organization means evolution from various initial hollows towards regular chair-like notches and further on - towards a privation plateau. The self-organization of a fluvial system manifests itself in development of concave channel profile and regular meanders pattern; some channel forms (ridges) also develop; the relief of the drainage basin decreases. Positive feedback within a system results in more resistance to external noises, That is caused by negative feedbacks strengthening.

Three principles are discussed co-existing in fluvial systems hierarchy, that are functional, territorial and temporal, each of them having its own feedback system and spectrum of noises.

Islands can be subdivided into three types: continental, oceanic and those of transit tonal zone. Oceanic islands are presented only by volcanoes and atolls. Erosion and wave action are main exogenous processes modeling volcanic islands. Four factors control the atolls evolution, i. e. coral colonies' growth, fluctuations of the ocean's level, wave action and debris lithification.

Youngest parts of islands are surface of the reef platform, atolls' built-up islands, back parts of beaches and bars, their age being 4000 y. B.P. up to the present. Many of low marine terraces at rising islands are of the Holocene age (2-4 thousands y. B. P.). At tectonically stable islands low terraces date back to Sangamonian or Middle Wisconsin time. High terraces were built during eustatic transgressions. The volcanic islands: came into being 3-2 mln. y. B.P., some of them belonging to the historical time. A general scheme of formation and evolution of oceanic islands is proposed.

Field observations at test sites gave values of erosion of road cut slopes consisting of Oligocene terrigenous subflysch, During the period of observations (513 days) the quantity of rock matter removed by slope processes was 140,7 kg/m² at north-facing slope and 96,8 at the south-facing one, the slopes' retreat value being 64 and 44 mm respectively. Mean annual erosion intensity- at the northern and southern slopes is 100,1 and 68,9 kg/m² or 46 and 31 mm. It will take respectively 22 and 32 years to remove a layer l meter thick. A certain dependence of the process on the Slope's exposition and steepness has been found. At the first test site the slope is north-facing 60o steep; it retreats 1,5 times faster than the south-facing slope 45o steep, debris dimensions at the first site being larger.

Irrigated area creases each year in the steppe zone. It changes noticeably the morphology of the steppe plains. A special kind of irrigation topography: is formed, its studies being of both scientific and practical importance. It has become necessary to develop a general classification of the landforms due to irrigation.

The authors analyzed geology and geomorphology of the morphostructures in several transitional regions 'from ridge to depression and concluded that large and complex morphostructural bands marked the transition. The data given on the morphostructures of the transition zone of epiplatformian orogenes suggest the morphostructures to be of widespread type. Origin and special features of the zone are controlled by deep faults, Transition «ridge-depression» zones are linear, they are characterized by a network of active faults, differentiated mosaic tectonic pattern, variety of geological structure, complex character of topography and wide spectrum of exogenous processes.

A longitudinal profile of a valley is discussed which is drawn considering -the river's discharge. Analysis- of such reduced profile makes possible to distinguish the influence of rocks resistance and of differentiated tectonic movements as well as to estimate them quantitatively. 50 tributaries of the Burinda River (the Amur drainage basin) have been analyzed using the described technique and a schematic map of relative block movements have been compiled.

Morphological, geological and geophysical data are discussed which were obtained at two proving grounds in the central Tunisian Strait. Morphological schemes of the sites were compiled. Data of echo-sounding when compared with seismic profiles, magnitometrical data and geology of Ljnos and Lampedusa islands contribute to clearer view of block structures of un-studied as yet parts of the strait.

A diffusive model of undercut slope is developed, where the undercutting effect is taken into account by the zero condition at the moving boundary. A partial auto-modeling solution has been got, which corresponds to the stationary dynamic regime stage (parallel retreat of the slope); the result is that the more active undercutting is (when compared to erosional downwearing), the steeper the slope becomes. A character of general solution of the problem is studied for the initial exponential slope profile similar to the profile of stationary dynamic regime. Analyzing both theoretical and numerical solutions together, the following conclusions have been drawn: 1) if the rate of undercutting is below the critical one, the slope down-wearing occurs; 2) is the rate is equal to critical (b=CK), the parallel retreat occurs; 3) if the rate is above critical, the steepness at the base of the slope increases and it loses its stability. In conclusion some prerequisites of experimental modeling are discussed as well as some further trends of the mathematic modeling.

Comparative analysis of three sections of fluvial sandy terrace at Central Yakutia revealed changes in the slope's structure during the Holocene. At the east-facing slope the defluction is the prevailing process; the slope inclination decreased from 42 to 28^o, a 10-5^o deluvial apron being formed at the slope base. At the north-facing slope defluction goes with cryosolifluction; at first the upper part of the slope was flattened (to 28^o), and then retreated as the lower part decreased in steepness to 15^o and deluvial-solifluctional apron was formed (the latter being 9 to 3-4^o steep).

A new volumetrical method is introduced of the investigation of present-day geomorphological processes. The volume-forming processes include the volume increase due to vertical rise and bringing the lithospheric blocks into region under study by tangential crust movements, accumulation, volume decrease due to down-warping and blocks' movement out of the region; erosion. Quantitative study (in terms of volume) of main geodynamic processes results in definition of trend of the relief evolution (uprising, equilibrium, descending) and its rate, the latter being calculated using the following equation: И=Vтп+Va-Vту-Vд, where И - rate of relief evolution; Vтп - volume of lithosphere brought by tectonics above a conventional level, Va - volume of built-up forms, Vту - volume of lithosphere removed by tectonics below the conventional level, Vд - volume of matter removed by erosion from the surface and interior parts of the present-day morphostructures. All values are reduced to area units per year.

Various distortions of the Earth's surface can appear in the pleistoseiste area during earthquakes more than 7 intensity, i. e. fissures, scarps, rockfalls, landslides ertc. Formation and size of the distortions are controlled by landforms and their elements position with view to seismic ray exit direction, depth of dissection and slope steepness. Slope stability is influenced by tectonic structure, composition and state of the rocks (lithology, weathering, fissures) as well as by hydro geological conditions.

The shelf topography is described as well as parts of continental slope and continental rise near the Kerch and Taman peninsular. The bottom landforms are interpreted in terms of their structure using the data on the peninsulas and shell geology. Main structural elements of SW-NE strike are proved to be distinctly pronounced at the shelf and possibly at continental slope and rise.

The paper discusses the classification of surfaces of destructive landforms as objects of mapping. The evolution principle of the systematization based on classic theory of landscape stadial development is suggested. The dissection and planation surfaces make two general classes corresponding to the ascending and descending phases of the cycle of erosion. The intermediate subclass of the planation-dissection surfaces is considered to form during the stage of late maturity. The further division of surfaces is executed after initial surface-forming processes. Thus the dissection surfaces may be tectonic, fluvial, marine-abrasional etc. The planation surfaces of the last stages of the cycle make only one genetic type of «denudational surfaces». The genetically various surfaces of two evolution classes are pictured in two different sets of colors. Numerical or verbal nomenclature of local cycles of erosion is proposed for indication of the relative age of the surfaces.

The article revises the fluvial terraces' terminology and typology. A geomorphological classification is introduced, consisting of two classes, four types and eight sub-types of the terraces. Criteria of the classes and types identification are formulated in terms of dynamic phases of alluvium, load budget changes in the course of fluvial processes, structure and thickness of alluvium, morphological features of surfaces. A necessity is argued to unify the geomorphological content of various fluvial terraces types, including accumulative, equilibrium accumulative, erosional accumulative, erosional types.

A monograph on terraces and terrace series

The XVI Plenum of the Geomorphological Commission