Quantitative analysis of the transform displacements in Mid-Atlantic rift zone has been carried out. In general, sinistral displacements predominate. Consequently the west drift of American lithospheric plate predominates too, but nevertheless the seafl oor symmetry is well preserved. It means that centre of spreading migrates to the side of removing plate. Migration takes place by the spreading centre jumping. That is how segmentation of the rift zone occurs. In other words constant reproduction of the symmetry exerts primary control over the formation of the sea fl oor morphostructure. The line of spreading centre migrates along the ridge from a segment of one age to a segment of different age on the model of relay race. This suggests a conclusion that submeridional breakup in the place of modern Atlantic has been existent since the Pangea breakup and has been evenly developing through time.

A river channel in mountainous countries is controlled by two main factors: 1) tectonic activity of the terrain; 2) lithology of bedrock defining its characteristics of weathering; by latter criterion the majority of rocks has been divided into two main types: break-stone and block ones. Easily erodible rubbly bedrock supplies rivers with affluence of fragments having the same sizes as bedload sediment. That is why incision gives way to lateral erosion at relatively high valley gradients, and a river, being locally overloaded with sediment, acquires the braided pattern. In bedrock of the blocky type, the supply of bedload sediment is scanty; progress of erosion cycle is slow; as a result valleys with low gradients and meandering channels are worked out. The data on the distribution of river channel types in the eastern Russia confirm the concept discussed.

Total megapolis infl uence on small rivers leads to general hydrograph levelling and rain fl ood peaks growth, extension of active fl ow period, and abrupt variation of hydrological river parameters. The most signifi cant impact is exerted by concentration of discharge/leakage areas of technogenic waters, resulting in drying up of certain valley ranges, and excessive raise of water level in the others, which leads to gradual transformation of river basin: active development of certain water fl ows and regression of others. Erosion and accumulation in city river valleys are conditioned by local technogenic factors and occur in relatively short ranges. Geomorphological function of spring fl ood is decreased, and its active role in the valley bottom formation and cleaning vanished.

In the Volga-Ural bitumen zone, bitumen is concentrated in upper part of terrigenous sandstones of Sheshmian horizon of the Upper Ufimian substage. Sandstones form buried swell-like ridges up to 3-5 km long, 0.5-2.5 km wide, and 25-40 m height; to the top of them bitumen deposits are confined. For a long time these forms were considered as the bars of the end of the Early Permian epoch. New data (parallel orientation of these swells to contemporary river valleys, their location in the Middle Sheshma river basin, distinctive positions in swells, character of bitumen outpouring on the surface) bring us to accept their exotectonic origin. Owing to non-uniform static pressure, swells have been formed in strongly dissected relief at the turn of Miocene and Pliocene. Bitumen diluted high-porous sandstones, which were squeezed out from under watersheds in the direction of river valleys, where overlying rocks pressure was less. Similar subsurface folding in plastic rocks is widespread in the whole Middle Volga region. Distinct from those above geological and geomorphological conditions in neighbor areas restrict territorial distribution of bitumen deposits to Middle Sheshma river basin

Morphometric parameters of the 3 selected slopes derived from DEMs of 3 different scales have been used for soil erosion modeling. Model estimations for each of the 3 topographic input datasets and for 5 different crop rotations showed that the discrepancy between the results produced by different morphometric data in some cases exceeded variability associated with the impact of crops. Comparison of model results with soil profi le morphology method showed general comparability of erosion patterns obtained by two approaches, but emphasized the need to have control key sites were average model values of erosion rates can be tested against an independent fi eld-based technique.

Hazardous geomorphic processes were revealed at the Fiagdon-Terek interfluve on the base of ground aero and cosmic images, fi eld research, and historic data since XVIII century. These results were used for compiling the ecologo-geomorphic maps in the 1 : 200 000 scale. There have been no distinct changes in relief and in the boundaries of the geomorphic processes distribution areas but the Genaldon valley, where in 2002 glacio-rock torrent caused ecological catastrophe. The map of dynamics of hazardous local geomorphic processes was compiled in the same scale. There occur recurrent processes on some local territories and single-shot ones on the others, earlier had not been subjected to such processes. The latter territories tend to stabilize later.

The history of the development of the South Primorye Islands represents a phenomenon of the conservatism of landforms which have formed more than 250 million years ago and were preserving their morphology and structural-substantial basis up to now, in spite of the tectonic regime inversion and repeated changes in morphogenesis conditions. General evolution of this Island system of rises is described by the following schematic model: volcano-plutonic ridge (P2) - intrusive horst (P2) - buried horst (T1-2) - regenerated horst (K2) - residual horst (N1) - a number of uncovered domical and block structures (N2 - Q4). The cause of the prolonged heredity of their development seats in a number of factors: increased thicknesses of granite-metamorphic layer - roots of mountains - under the orogens and individual tectonic-magmatic rises; existence of a skeleton network of deep faults; prevalence of vertical tectonic motions and others. The comparative analysis of regional schemes of the Russian Southeast orogenic systems (geosynclinal-folded, arch-block, terrane and others) formation and development showed that the incompleteness of our knowledge about geological structure and morphogenetic processes causes the dependence of historic-genetic reconstructions on the subjective views and the purposes of researchers

Mathematical simulation of ephemeral streams structure forming on the isolated hillslope is described. The networks of ephemeral streams formed under conditions of the uniform water inflow onto surface of the hillslope with randomly generated relief. Relationships between modeled streams network structure and input model parameters are studied. Coefficient values of stream parameters changes for river networks, gully networks and modeled ephemeral streams networks have been compared. Their closeness indicates that there exist general laws for forming ephemeral and constant streams systems on the surface of the Earth.

To the 80^th anniversary of outstanding Cheskey geomorphologist Jaromir Demek

To the 100^th anniversary of Boris Fedorovich Kosov

 

To the 80^th anniversary of Piotr Andreevich Okishev

Jubilee of academician of Poland Academy of Sciences Leshek Starkel

The book review “Leontiev Oleg Konstantinovich. Memoirs of contemporaries”, MSU, 2009. 242 p.