The interpretation and generalisation of the results of the geomorphological, geological and geophysical investigations in the light of the plate tectonics make it possible to distinguish four main stages in the development of the Earth morphostructure in MesOzoic and Cenozoic: 1) the Pangea disintegration, Laurasia, Gondwana and the Tethys ocean formation (Late Triassic - Early Jurassic), 2) the Gondwana disintegration, the Atlantic and Indian oceans opening, Tethys maximum development and beginning of reduction (Middle and Late Juras-sic - Early Cretaceous), 3) the Laurasia disintegration, Mesozoic folding structure formation on the Pacific continental margins, Atlantic and Indian oceans formation and the Arctic ocean opening, the main ocean morphostructure system formation (Late Cretaceous - Early Paleogene), 4) neotectonic stage - young and rejuvenated mountain systems formation on continents, active oscillation movements on platforms, the modern mid-oceanic ridge system, ocean basins and transition zones formation, the denudation modelling of the global relief (Late Paleogene - recent time).

A subject and methods of historical and paleo-channel studies are considered, this special branch of science deals with history of channel-forming actives of rivers. The studies are of importance for paleogeographic reconstructions of fluvial relief-forming processes and for better understanding of modem trend in the processes.

Morphostructures of the Great Caucasus may be explained both from neomobilistic points of view and in terms of geosyncline theory. The valley network originated using faultline system. At the neotectonic stage, the water divide coincided with the Glavny Range. During the Quaternary, tectonically more active Bokovoi Range was rising, it formed an orographic axis of the arch-block uplift, though not the divide (as indicated by antecedent character of transversal valleys, distribution of terraces and segments of alluviation and erosion in the valleys). There are no morphostmctural nor neotectonic evidences of the water divide migration form the Bokovoi Range to Glavny one.

At the neotectonic stage the Western Caucasus developed as an accreting mega-arch complicated with a system of superimposed horsts and grabens, different in age and in order and oriented both along and across the arch's axis. The block structure was alternately activated at different stages. The river network readjusted itself to the changing differentiation. Transversal valleys more likely use tranversal grabens than develop as watergaps resulting from general migration of the main water divide.

Geodynamic mechanisms are discussed with a view to their geomorphic effect in the development of morphostructures in Azerbaijan and Eastern Transcaucasian region resulting from the collision between the Eurasian and Arabian plates in the Caucasus - Asia Minor sector. A multilayered structure of overlying thrusts has been identified in the mountain systems of the Great and Lesser Caucasus, Talysh, Kula intermountain rift, the structure is reflected in geomorphology as a system of longitudinal morphostructural steps and transversal blocks, general asymmetry and curvature types of mountains, various types of underthrusts, river network outlines, etc. The maximum pressure of the Arabian cusp and the orogens formation falls on the Pliocene - Quaternary time. The leading role in the process belonged to horizontal lateral shifts, overthrusts and underthrusts, pulsatory compression and tension, planetary and regional fault systems, changes in the Earth rotation regime. Principal mechanisms of collision are manifested also in the recent tectonics.

On a limitations in the Baer's law interpretation

The small rivers degradation in European Russia is considered as resulting from agricultural cultivation of their basins and consequent increase in the rate of man-induced erosion on interfluves and alluviation of channels and floodplains. The authors developed a technique which permits to identify correctly spatial and temporal changes in small river length, degree of silting, and the mechanism of silting. History of the land cultivation in the European pan of Russia is briefly stated.

The paper describes the extent of small river systems transformation in Byelorussia and its results. More than 500 small rivers have been completely corrected, with their watersheds meliorated. Total length of regulated rivers amounts to 15.7 thous. km. Construction of drainage sewer network resulted in that many interfluvial bogs were dried and transformed into agricultural lands. Some negative consequences are discussed, such as increase in erosional dissection density. Some predictions are stated about further development of the processes.

Объединенный институт физики Земли РАН

Some procedures have been developed for studies of cavity configuration changes primarily due to seismic impulses (with reference to the Crimea Spatial geometric and azimuthal approaches often permit to distinguish cavity collapses due to their gradual destruction from those resulting from earthquakes. Considerable attention has been given to archaeological data as means of collapse dating. Information is given on the seismic effect on the Crimean caves during the historical period, together with examples of various types of collapses in the past.

Different approaches are considered to define the notion of «inheritance of topography». A proposed technique of morphological inheritance studies is based on hypsometric analysis of relief dated to different epochs. The paleo-relief reconstruction and following procedures are automated by the use of geoinformation system of the key area. The studies result in a map of types of inheritance, three type of inherited topography and two types of inversed topography being recognised.

The paper describes modeling in the solid runoff changes within an erosional system which permits to recognise principal regularities in the changes; .causes of the changes are discussed.

The comparison between the means for limiting the area of active ripples existence with observation data shows inability of earlier methods to establish the limits reliably. It is shown that the limits can be determined using functions relating sand particle dimensions or orbital radius of motion near the bed to particle Mobility characteristics or the Shields parameter; the functions are more complex than linear or power ones. The relationships between active ripple dimensions and orbital radius and mobility characteristic as developed by the authors are more reliable than previously known methods. Equations are suggested for calculation of passive ripples maximum dimensions, and a possibility of dynamic reconstruction based on the data on the forms is established.

For 15 years observations of more than 75 heads of small erosional landforms development were carried out within a large Satino erosional station (the Protva River basin) using fixed markers technique. The observations provided not only new data on dynamics and morphology of small erosional landforms within the Moscow glaciation marginal zone, but also enabled to compare the quantitative information on the gully development with the meteorological materials of VNIGMI. The following meteorological characteristics appear to have bearing on the erosion activation: water stored in snow at the beginning of melting in excess of 90 mm, spring coming with a rush in case of the low ice content in the soil or slow spring in case of high ice content. The results prove the spring snow melting to be of primary importance for headword growth of small erosional forms as compared with rain-induced erosion.

Questionable opinions on the paleogeography of Eastern Europe and West Siberia

The most important geomorphological aspects of the neotectonics

Gully erosion: primary landforms of the hydrographic network

Eolian processes and landforms: a symposium in Poland