The article deals with general conditions of the river channels formation at Siberia, reveals some spatial regularities of various types of channels and traces their relation with factors controlling the channel deformations character. On this basis the Siberian territory has been subdivided according to degree of geological and geomorphological control of channels (regions of free and limited development of channel deformations have been identified) as well as according to the type of channel-forming discharge. Regularities of development of me-andering and braided channels, prerequisites of many channel formation at floodplains etc. have been revealed depending on different factors combinations.

The special features of the Siberian rivers development show the necessity of working out regional schemes of river channels regulation considering requirements of various branches of economy.

A new classification of the World Ocean bottom relief is introduced taking into account division of the terms into geomorphological and geostructural ones. According to the type of the earthcrust are identified continental masses, oceanic depressions and transitional zones (from oceans to continents). According to sub-types of the earthcrust an oceanic depression is subdivided into ocean floor and mid-oceanic ridge, and the transitional zone-into basin seas and island archs systems. In dependence on Mesozoic-Cenozoic tectonic movements the continental margins are subdivided into subaquatic parts of fold-block elevations (mountains) and subaquatic parts of continental plates and masses (plains); floor of basin sea - into deep-sea troughs and inner elevations, island arch system - into island arch itself and deep sea trench, floor of the ocean - into oceanic troughs and rises.

These units are subdivided further into those of smaller order according to geological structure, type of Neogene-Quaternary earthcrust movements and predomonant exogenous relief-forming process. Some previous classifications are discussed and new propositions on terminology are made.

The tectonic and morphostructural control of oil and gas fields location is essential but not the same at the whole territory of the USSR. Within areas of subsidence the hydrocarbons tend to move into regions of local neotectonic uplifts, the gas (as more mobile fluid) is distributed in closer connection with neotectonic structures. Within areas of uplift the oil and gas fields were destroyed because of seal failure of enclosing layers. Negative was also the influence of inverse morphostructures formation (elevations and plateaus) which replaced ancient tectonic depressions and troughs during the Neogene-Quaternary. The hydrocarbons accumulation in geological traps was favored by direct morphostructures formation in the course of inherited earthcrust movements within regions characterized by neotectonic uplifts of small amplitude (less than 900-1000 meters).

Using analysis of variance (factorial) and correlative technique the relative significance of different factors of placers formation for stanniferous placers dimensions at the MPR territory was determined as follows: order of the stream, the valley of which contains the placer - 30,2%, distance from the placer to the mineral source - 20,6%, stream density within the drainage basin where the placer is formed - 12,0%; loose sediments thickness - 9,7%, type of mineral source - 6,8%, all the rest factors - 8,0%, total significance of the considered factors combinations - l3,4%. Form, degree and direction of correlation between the factors under discussion and placers scale are estimated using coefficient of correlation.

According to calculated data the most prospective areas for large 'tin placers search are parts of overdeepened valleys of III-IV order situated within 4 km from mineral sources in the drainage basin with stream density about 1,1-1,3 km per km².

The gully erosion at the Tadzhik SSR territory is characterized, causes of gullies formation are revealed, some data on rate of gully development and on gullies morphology are given. It is established that Central and South-Eastern Tadzhikistan is most affected with gullies. One of the most eroded regions - Faizabad - is discussed in detail. Three maps of the region have been compiled-gullies density within geomorphological zones, general density and areas of gullies. The most gullies density appeared to be in the zone of medium height mountains, the least density-in the high mountains and valleys. The gullies density and areas are in close connection with rock lithology, the maximum values being confined to Cretaceous rocks and minimum values - to solid rocks.

A method of disjunctive dislocation study is considered using linear landforms connected with outlines, the former being traced at topographic maps, aerial photographs or by visual observations from airplane. The method (used together with geological studies) revealed ancient and neotectonic faults of various orders as well as tectonic zones characterized with high density of fractures. Neotectonic faults are mainly up thrusts, strike-slip faults and tear faults. There were established three types of neotectonic rejuvenation of ancient faults: direct rejuvenation, dispersion and shift. In case of direct rejuvenation the neotectonic movements take place directly along the ancient fault plane, in case of dispersion a zone of neotectonic fractures develops instead of a single fault, while in case of shift the most active neotectonic movements take place aside of the ancient tectonic suture.

The method of geomorphological lineaments applied to disjunctive dislocations can be useful for regional and detailed geological studies and ore prospecting including those in ore regions and within ore fields.

The proposed technique of longitudinal stream profile analysis is based on relation between morphometric characteristics of profile and watershed area. The main criterion of the estimation of stream profile is index of erosional dissection, its value being mainly controlled by stream discharge. The technique of stream profile analysis allows to define the significance of differentiated tectonic movements by the way of successive elimination of such important factors as lithology, water discharge etc.

A series of density field maps has been compiled for a region of the Donets Ridge showing gully erosion in statics, dynamics and in interrelations with erosional control factors. Visual and statistic analysis of maps revealed regularities of distribution and development of the erosional processes. Gully erosion development is forecasted for the coming 25 years.

The Late Cenozoic history of Aldan-Chulma depression manifests itself in the special features of distribution and composition of Quaternary deposits belonging to periglacial, alluvial and slope series, as well as in patterns of watershed heights. On this basis has been revealed the zonality of neotectonic structures of the depression, approximately corresponding to the zonality of Mesozoic structures. However, relations between Mesozoic and Cenozoic structural plans are those of inversion: maximum Cenozoic uplifts correspond to maximum. Mesozoic downwarping. The analysis of the distribution of watershed heights within the outlined neotectonic zones suggests the fragments of three planation surfaces of different age correlated with general Siberian surfaces as well as deformations of one of these surfaces which fragments are mostly widespread. Arch-block character of the neotectonic structures is established and the amplitudes of deformations of different order are defined.

Seshchin glaciodislocations situated at the boundary of Bryansk and Smolensk regions near Roslavl are related to the Middle Pleistocene push moraine ridges embracing gigantic preglacial trough. Different viewpoints indicated in literature are considered of the conditions of these glaciodislocations' formations.

A new hypothesis is suggested according to which detached masses are of scale structure. Glacial ploughing took place there in the course of continual detachment of bedrock masses. This hypothesis is confirmed both by concrete geologic- geomorphologic data and the results of theoretical studies in glaciology and geological engineering.

Within the littoral zone of the North-East Caspian Sea the relief develops under conditions of steadily lowering sea level. The controlling factors are surge phenomena which account for wind-induced drying-up of the littoral zone, extreme flatness and homogeneity of sea floor, salt tectonics which results in typical winding of coast line.

An alternation was established of stages of differentiated tectonic activity of small individual morphostructures and stages of prevailing development of main morphostructures (such as largest ranges, mountain systems, intermountain depressions) since Late Paleozoic up till now. The process controls the development of mountain morphostructures of Central Asia. The existing scheme of mountains formation during Oligocene-Miocene and their successive growth and enlargement is but a particular regularity within more general process and characterizes -only the time interval from Middle Pleistocene to the present day. These are facts which confirm the statement and indicate the independent uplift of low foreranges during Neogene comparable in dimensions with that of main ridges. Some special features of morphostructural development of low foreranges during Neogene are described.

Impact of tectonic subsidence on sea coast evolution was studied with reference to development of eastern abrasional coasts of the Azov Sea. Tectonic subsidence has been proved not only to accelerate the coast abrasion but to change the character of the process: while under conditions of constant sea level the shore abrasion terminates in equilibrium profile, there is no natural stabilization of the coastline under subsidence conditions, the coastline constantly retreats with the rate increasing as the tectonic subsidence accelerates.

Within the limits of the Russian Plain there were estimated ratios of relief rhythm at water divides of different orders (corresponding to highest parts of moraine uplands) and analyzed spatial pattern of the ratio values. The relief rhythm ratio proved to depend on relative age of glacial morphosculpture.

Sea coast zone as observed from airplane and from under the water

On the significance of alongshore debris movement for the accumulative forms construction at open ocean coasts