The age of planation surfaces of SE Africa has been revised. The dominant surface -cutting Pre-Cambrian and Lower Paleozoic rocks which L. King considered to be of post-African (locally African) Cenozoic age has been proved to be post-Gondvanian Mesozoic planation surface. Both African and post-African surfaces are widely spread only within areas of loose Mesozoic and Cenozoic deposits.
Forms of the present-day topography and those of the Pre-Quaternary bedrock surface are identified and sorted according to their size (largest, large, medium etc.) in order to specify the morphology of the SW Russian Plain. An analysis of most important factors controlling the relief formation (such as basement and sedimentary mantle structures, neotectonics, Pre-Quaternary erosion and sedimentation, glacial erosion and accumulation during Pleistocene) as well as some quantitative indices allow to distinguish several types of large and very large landforms at the NW Russian Plain, as follows: tectonic; tectonic-erosional, mostly due to fluvial erosion, tectonic-erosional, mostly due to- glacial erosion, tectonic-accumulative, built-up, with erosional socle preconditioned by tectonics; built-up, with erosional socle, built-up, formed by glacial erosion.
Nivation is an intensive thermogenous process of rocks' destruction which acts near snow banks in spring and summer, it is widespread in mountains and high latitudes. The privation results from the solar energy which causes sharp contrast in temperatures of bare rock surface near the snow, surface under the snow and air near the surface. The intensity of privation, the rate of rocks' destruction is controlled by amplitude and frequency of the temperatures fluctuations within the active layer near the snow's boundary, effective heat capacity and coefficient of thermal expansion. Being a thermogenous process the privation acts not only near the snow banks but glaciers and icings as well.
Discussions
Main features are discussed of geomorphological theories developed by W. Davis and W. Penck; prospects for the future of geomorphology are estimated. Considering old and new ways of the geomorphology the author describes main tasks of planetary, synthetic, dynamic and historical geomorphology, problems of relief-biosphere connection and human activity significance for morphogenesis. Notions of «geomorphologica1 environments» and «geomorphological series» are introduced. The author comes to the conclusion that there is no crisis in geomorphology's theory nor practice.
The cause of the discussion is uncertainty of the subject, terms, notions and theoretical grounds of the methods of the science. A principle of the relief study is introduced within the frame of morphostructures, the latter being considered not as landforms but as the background of relief formation, the relief is formed by various processes of erosion and sedimentation against this background.
Summing up the discussion on the matter of geomorphology and morphostructural analysis
History of Science
Fruitful ideas of Yu. A. Meshcheryakov and their significance for the geomorphology's progress
Short communications
The paper discusses the mountain streams channels formation at the Western Tier Shan, differing in mudflow frequency, channel morphology, alluvium composition and biogenous factor contribution to rock particles destruction. Biogenous destruction of pebble and boulders is estimated.
«Blind» cavities of ellipsoidal cross-section on caves' walls and ceiling-so called «Korrosionskolke»-result from the corrosion due to mixing two non-agressive water masses forming together an aggressive mixture, According to A. Bogli the cavities are formed when surface water seeps along fissures and mixes with karstic water filling the cave itself. Studies of multi-layered cave system Kudaro in South Osetia have brought the author to the conclusion that the «Korrosionskolke» may be formed if the water seeping along fissures mixes with condensed water, the cave itself not being filled with water.
An analysis of structural-geomorphological schemes and geophysical data on the Western Pacific allow to suggest that the complete profile of continental margin includes: inner shelf, continental slope in the process of formation, outer shelf, depression at the outer shelf, continental slope of marginal sea, basin of marginal sea, island arc, continental slope of ocean, deep ocean trench. The description of the elements morphology is given as well as some speculation concerning the evolution of the continental margin.
Long-term observation (1963-1975) on 56 gullies growth at 7 key sites at Ulyanovsk region revealed quantitative indices of the gullies growth and their relation to various meteorological factors, angle of slopes, rocks lithology, vegetation type and anthropogenous factors. Graphs of the correlation are drawn and interpreted.
The bathymetric and geomorphological charts based on geomorphological and geological-geophysical data obtained as results of the investigations of RV «Akademik Kurchatov» and submarine apparatus «Pisces» are compiled. The detailed description of submarine topography is made and an opinion about its origin and the history of the Red Sea rift evolution is commented.
Upper surface of karsted massifs covered with fissured rocks is considerably rugged due to various rate of chemical erosion controlled by density of tectonic fissures. Three main elements have been identified by the authors in the buried karst topography of Polaznensky massif. 1) Depressions corresponding to places where overlying rock is densely dissected by fissures. The depressions are filled with collapsed debris and karstic deposits including fragments of both soluble and unsoluble (overlying the massif) rocks. 2) Saddles between outliers corresponding to places of medium density of fissures. They are covered by collapsed fragments of mostly unsoluble overlying rocks. 3) Outliers which correspond to areas of unbroken rocks and are covered with insoluble rocks in their primary position.
Reviews
ISSN 2949-1797 (Online)
