The author describes geology and main geomorphic features of the largest Azores island - San-Miguel, which he visited in January 1977 during the 24th cruise of the research ship «Akademik Kurchatov». Detailed investigations of oceanic volcanic islands like Azores are of importance considering the new theory of the global plate tectonics. A number of problems of local and regional importance have been put forward as a result of the analysis of geological data from geomorphological point of view, the necessity of their consideration having been stressed.

Morphostructures of Bulgaria and eastern Balkan Peninsula underwent changes and transformations more than once during their long and complicated development. Hence their base is heterogeneous, the morphostructural integration was not achieved until the neotectonic stage when the present day orography came into being. The morphostructural differentiation reveals block structures of the earthcrust and deep faults control.

The largest morphostructures are as follows: I - the Danubian (Mizian) epiplatform plain, II - the Rhodopes median mountain massif, III - Kraisht-id-Srednuogora block-faulted low mountains, IV - Stara Planina epigeosynelinal mountain system, V - complex of accumulative surfaces within the limits of young foretroughs and intermountain depressions, VI - the Black Sea basin.

An alternation of geocycles and morphocycles in the relief development resulted in planation surfaces formation and changes of drainage pattern. Five main erosion surfaces can be identified, which belong to the neotectonic stage: two summit levels (Late Oligocene-Early Miocene and Tortonian- Sarmatian) and three lower post orogenic levels (Early Pliocene, Late Pliocene and Late' Pliocene-Early Pleistocene). There is also a broad regional Meso-Cenozoic planation surfaces as well as buried levels, the latter being formed before Permian, before Triasic, before Early Cetaceous, before Late Cretaceous - Early Tertiary and before Late Eocene-Oligocene. Drainage pattern reflects main features of the morphostructural plan. Its changes mainly date back to L.ate Pliocene and Pleistocene. Pre-neotectonic river valleys are practically of no significance to the recent topography.

The morphostructural differentiation is in close connection 'with deep structures of the earthcrust and the upper mantle, both direct and inverse relation being traced. Structural geomorphological studies are conducted with the aim of search of minerals and mineralizing faults, metallogenic and seismotectonic zonation of the Bulgaria, studies of recent crustal movement, thermal spring activity etc.

At the slopes of the Tatar vault facing the Kama - Kinel trough system the buried Tournaisian surface is dissected mainly by karst forms. The erosion-karstic depressions controlled sedimentation and formation of various oil traps in the Lower Garboniferous rocks. The authors' studies permit to improve methods of oil searches.

Wind velocity increases within deep river valleys with high slopes (confuser effect). Under such conditions asymmetric ridges are formed 'on the sands of Valdai (Wiirmian) river terraces, transversal to prevailing wind direction, and barldians develop .at their tops. The ridges have oscillatory movement and have not been covered by vegetation since at least Late Pleistocene (23-16 thousand y. B. P.). The authors suggest to create reservations at these sites and to conserve them as rare natural phenomena.

The paper deals with terraces at the Aral Sea coast, number, height and age being discussed of the proper Aral Sea terraces as well as terrace levels out of the limits of the Aral basin. Geomorphology and geology of low and high Aralian terraces (of the Small Sea) are described and compared with similar levels observed at other parts of the coast by number of geologists. The author came to the conclusion about recent transgression of the Aral Sea (up to 60 meters a. s. l.).

Geomorphological and geological evidences are given about the existence of individual Aral-Siarykamysh terrace (68-72 meters high), its surface being traced through Algal, Sarykamysh and Assake-Audan depressions. Uncertainty of its age is stressed and some considerations of its relative youthfulness are given.

A continuous debris drift has been traced for 80 kilometers, from the Mzymta River mouth to Myussera Hills. The discharge and composition of debris within individual zones fluctuated more than once depending on coast exposition, sea depth near the coast and quantity of alluvium coming from the land. These factors control considerable changes of the beach width above the sea level. A considerable loss of debris takes place at one part of the coast through a submarine canyon. Main part of material accumulates at the steep submarine slope near the Pitsunda Promontory. Between the Khashupsa and Joekvara mouths the debris drift if discontinuous and the debris move only during strong western storms. The authors suppose storm currents are essential for pebble and even boulders movement along the Gagra Bay coast.

Paleo-morphostructural analysis of buried Pre-Pliocene relief of South-Western Turkmenistan allows to conclude about reverse correlation of the Pliocene - Quaternary and Cretaceous-Paleogene structures, the conclusion being of importance for the search of oil and gas bearing structures in Mesozoic rocks.

Some considerations are given of the problems discussed in the paper by N. I. Nickolayev «On the content and main tasks of geomorphology» («Geomorphology», n. 4, 1976). The authors give their own definition of the geomorphology and its object. In their opinion, the latter is morphology, origin and age of the solid Earth relief, both present and .past one, with the aim of revealing its history and laws of evolution. The object of the geomorphology, i. e. the solid earth relief is defined as a part of space limited by lithosphere-atmosphere and lithosphere-hydrosphere boundary surfaces from above and the geoide surface from below.

Analysis of the composition and occurrence of the Lower Cenozoic sediments reveals the Pre-Cenozoic age of the Altai Mountains, their structure being slightly complicated during the Cenozoic as a result of small-amplitude block movements. Late Cretaceous - Paleocene sediments (Karachum suite) present re-deposited Cretaceous weathering crust and include pebbles and debris; they form piedmont aprons and lake basins filling. During their sedimentation the erosion areas (dissected mountains) were clearly distinguished from areas of sedimentation - intermontane depressions, their position being close to the present. While compared, the palynological evidences from the Chuya and Tarkhatinsk basins reveal the difference in the basins altitude about 600-1000 meters which is similar to the present one, the basins altitudes being thus commensurable to the present. The younger Paleogene and Neogene sediments analysis confirms the notion of the permanent existence of the same pattern of mountain and depression relief. The conclusion on the older age of the modern topography than it had been previously suggested corroborates the evidences from the Tien-Shan and Pamir, and throws doubt upon the existence of the Early Cenozoic epoch of planation on global scale.

A new textbook on the geomorphology and the Anthropogene geology

The XIVth Plenum of Geomorphological Commission of the USSR Academy of Sciences