Small scale space images interpretation reveals geotectures features, i.e. those of lithospheric plates and erogenous sutural zones. Middle (regional) scale space images interpretation reveals individual morphostructures and allows to subdivide an area into morphostructural units, Interpretation of space images of high resolution (especially multizonal and multispectral) is promising for studies of morphostructures and geomorphic processes.

A great deal of nature studies reveal necessary conditions of transition of free meandering river channels into linear ones, the conditions are combined decrease in relative valley floor width and increase in degree of valley slope utilisation by the stream. Some criteria of channel type characteristics are given which may be applied to forecasting of channel forms developing in regulated rivers and artificial streams.

In many oil and gas bearing provinces of the USSR an identification of non-anticlinal oil and gas traps is a task of primary importance. As many traps are confined to ancient buried landforms, paleogeomorphological methods become more valuable. A complex of paleogeomorphological techniques is introduced. Individual regional discontinuity .surf aces and continental deposits are especially recommended for paleogeomorphological analysis in oil and gas bearing regions of the USSR.

Morphostructural analysis of Mongolian relief established a sequence of arches differing in stages of uplift and denudation, the difference is marked by special features of arrangement of Mesozoic magmatic (both intrusive and effusive) rocks which remain at various parts of the arches. The authors discuss the arches formation as result of intrusion and subsequent arise of acid magmatic melts, which satisfactorily explains the differences in arches morphology in terms of time of intrusion and distribution of acid magma in the earthcrust throughout Mesozoic time. The arches rise essentially disturbs the lengthwise metallogenic zonality, which results in appearance of alien ore formations within metallogenic zones.

Views of professor J. Obouin are discussed on the Mediterranean basins and adjacent mountains formation in terms of the new global plate tectonics.

The Sarykamysh is one of largest desert depressions of the Middle Asia, which was filled with the Amu-Darya water more than once throughout the Pliocene-Holocene. During Early and Middle Pleistocene as well as during last 350 years it was dry and modeled by arid processes. Since late 950th a disposal (mostly of waste waters) began from fields of the left-bank Khoresm oasis. At present a lake has been created within the Sarykamysh depression of about 2000 sq. km area and up to 40 meters depth, the water being brackish. The-inflow of water still exceeds the loss through evaporation; therefore the lake area is gradually increasing.

Dynamics of the Danube delta is characterized within time interval of about 100 years using comparison of space photographs ERTS 1972 and topographic maps dated 1888. Analysis of the dynamics revealed the active growth of the Kili part of the delta, marine abrasion and coasts' retreat between the Kili delta and Georgiev strait, sea laguna damming at the south of the delta. The inner (lakes and marshes) part of the delta is characterized by increase in water supply-which indicates the area's subsidence.

Debris fall and avalanche types of gravity slope processes are similar in mechanism but differ in intensity and result in landforms differing in geometry, debris sorting and stratigraphy, Space and time correlation of the landforms may give unique data on history of geomorphic evolution of mountain areas as well as help in solving some problems of practice.

Marginal features and boundaries of maximum and Vepsovo stages of the Valdai glaciation are described within the Vaga drainage basin, the forms being identified by aiephotographs interpretation and special field studies. Both petrography of gravels and boulders in the Valdai and Moscow tills and mineralogy of the tills corroborate the position of the Valdai ice sheet boundary established by geomorphic data.

In spite of some achievements in slope and slope processes studies, there are series of problems which still require development, such as zonal division of slope types, slope movements mechanism and seasonal features of slope processes. It should be also mentioned that knowledge of slope processes varies on a broad range in various regions of the USSR. One must be careful when extrapolating one region's features to another region. Data on Lower Amur region slopes suggest some differences resulting from low order's regularities (various regions belong to different morphoclimatic areas) besides some features of slope structure and evolution which various regions have in common (they result from all the regions belonging to the same morphostructural province).

Detailed studies of drilling and geological and geophysical data revealed buried deeply dissected (to 800 meters) topography at Southern Turkmenistan, dated from Pre-Late Pliocene. The buried valley net of ancient Amu-Darya and its tributaries has been reconstructed and drawn in countourlines («paleo-isohypses») as well as river system southward from Kara-Bogaz-Gol, which was formed under conditions of low Caspian level during the end of Middle-beginning of Late Pliocene. A certain connection has been traced between the paleo-landforms on one side and tectonics and lithological and facial features of the Meso-Cenozoic series on the other side. The authors concluded that such great erosional features could substantially influence the hydrogeology, baric conditions etc., which in turn could influence the process of hydrocarbons migration, accumulation and conservation in the upper part of sedimentary mantle.

Lower and Middle Pleistocene alluvial suites of the Upper Kolyma Upland valleys lie at small relative altitudes and are covered with Upper Pleistocene alluvium, the latter forming the terrasouvals surfaces. The same regularity is traced through the whole Upper Kolyma drainage basin which is located within an individual morphostructure of the Upper Kolyma Uplift rising during the Cenozoic. As structures of valleys and alluvium differ at different parts of the morphostructure, the morphostructural factor seems to be essential but does. Not fully control the valleys formation. The morphostructures influence valley profile form, relative altitude of alluvium of different age and subsequent distortion of ancient valleys floor. The terrace placers are mostly confined to local uplifts. Out of the limits of local morphostructures influence, the valley and alluvium structure is mainly controlled by complicate history of the valley evolution, typical for the region. As a result the ore bearing bodies are here not valley and terrace placers but buried placers.

Nickolay Aleksandrovich Florensov (to the 70th birthday)

Methodical aspects of river valleys studies

A book on time concept in geomorphology: Thornes J, B., Brunsden D. Geomorphology and Time. London, Methuen and CoLta, 1977, XYI+208 p., & 3. 45