Outstanding geomorphologist of the XX century Ju.A. Mescheryakov (to the 90^th anniversary)

To ascertain the Cenozoic evolution features of mountain relief we searched the traces of certain development stages, studied the deposits remained in summit mountain zone, and analyzed the correlative deposits, which structure corresponds to different relief morphology. Arial crusts of weathering in different relief types are characteristics of ancient planation surfaces; they are unconformable to present day mountain relief and reflect the early stages of the Sikhote-Alin and East-Manchurian arch development. Crusts of weathering were being developed in conditions of warm and wet climate and growing relief, they have reached their maximal occurrence in the Early-Average Miocene. Oligocene age of crust of weathering in the summit belt of Sikhote-Alin at absolute height over 1300 m was determined on the base of the studying the plant debris, diatoms, spores and pollen in alluvial and lake deposits Accumulation of coarse alluvium in hollows corresponds to epochs of rising. Geomorphologic position of relict crusts of weathering and character of geological sections in depressions of the Southern Far East prove the complex dynamics of relief formation. During the first stage (Pg-N²₁) some weakening of the Sikhote-Alin tectonic contrast took place; its morpostructure combined intermountain depressions, zones of evgemenic type, and mountain rises. The second stage (N³₁-Q) was the epoch of generalization of the structural- tectonic plan of this highland. This process was accompanied by the growth of highlands and by transformation of previous stage crusts of weathering into relict form.

Characteristic relief features of the Northern Eurasian rivers flood-plains indicate the changing conditions of the bottoms and flood-plains formation, and consequently their governing factors - the value and regime of the intra-annual flow and ground temperatures in the valleys. In the flood-plains relief at least three stages of Late Valdai and Holocene were revealed, which differ by their hydro-climatic characteristics. During the Late Valdai stage, the water content was high and relatively large landforms of the flood-plain arose; in the Middle Holocene, the water content was low and small landforms were formed; the Late Holocene has contemporary conditions of river bottom and flood-plain development. The obtained regularities of river formation may be used for the evaluation of the future changes of human life and activity on the riversides at a different climate change scenarios in the temperate zone of the northern hemisphere.

Karst sinkholes located in the eastern part of the Republic of Tatarstan have a different shape and age. The morphological sequence "cone-dish-saucer" relates to their age only in areas with similar geological structure. The field investigations proved that strongly fractured and karstified Lower Permian sulphate-carbonate deposits could absorb and accumulate a clastic material practically in unlimited amount. It was shown that the processes of cavity roof collapse, loosening and destruction of the Upper Permian rocks as well as suffusion of the fine clastic product play a major role in sinkhole development. The reservoir filling and seasonal fluctuations of water level in the large rivers are the main factor of the intensification of the process.

The Neo-Pleistocene tectonic activity in the north-eastern margin of the Baikal Rift Zone differed from that of the central Baikal sector. The neotectonic uplifts of the rift valleys mountain surround in the Stanovoi upland occurred in the Middle Neo-Pleistocene, which was confirmed by the results of palynological analysis and thermoluminescent dating. The regime of lacustrine sedimentation arose here more than once up to the Late Neo- Pleistocene. During the Late Neo-Pleistocene stage, the formation of the valley meso-landforms was caused mainly by climatic factors.

In the Upper Kolyma basin, the usually applied age criteria of relief-forming moraines of ancient mountain glaciers based on their heights are not valid and lead to the incorrect results which are included in the accepted stratigraphic correlations of Quaternary deposits of the region. More reliable and simple criterion of relative age of the moraines is proposed. It is age-related difference in the preservation state of the primary moraine relief, which has been long used on the planes. In two long-studied and one new test sites, we have investigated the morphology, location, composition of moraines, their interrelations, correspondence to the river landforms and alluvial deposits. As a result, three main morphologic groups of surface moraines were recognized: "fresh", "decrepit" and "smoothed" ones. The first and second ones correspond to the Last and Pre-last Late-Pleistocene glaciations, the third one - to both Middle-Pleistocene glaciations. These results may be used to more precise geomorphological and geological mapping of the territory, palaeogeographic reconstructions and planning of detailed palaeoglaciological researches.

The basin of the lake Svetloe was created before the Moscow Ice Age by karst process in carboniferous rocks. Deposits of the rim surrounding the lake are similar to those of kames, which arise from accumulation of aqueglacial deposits in the cavity under the dead ice, and after the collapse of the cavity roof in the englacial lake. The part of aqueglacial deposits was accumulated in the basin of the lake, while other part formed the annular rim on its shores. After the melting of the glacier, ice shores of the lake and part of its water content disappeared. The lake deposits remain as a rim elevated above surrounded plain. Some other crater-like basins in the Moscow region could be created by periglacial processes during late Moscow or late Valdai ice ages at the places of the collapsed pingos.

Earth-flow landscapes of the erosion right-bank slope of the Oka and Volga Rivers differ significantly both from the landscapes of the erosion-denudation flat interfluves of the right bank and from the low terraced accumulative left bank. We distinguish head-on and slopes - with active undercutting and side ones without undercutting. There are active landslides on the head-on slopes of the Oka and Volga rivers, and less active landslides on the slopes of gullies and balkas. Characteristic features of earth-flow landscapes depend on the history of relief development, geomorphological situation, lithology, and river lateral erosion. The four landscape-geomorphic regions are distinguished on the base of earth-flow landscape types.

E.A. Likhacheva’s jubilee

To the 80^th jubilee of A.A. Velichko

To the 100^th anniversary of the prominent geomorphologist M.V. Piotrovsky (1911–2011)

Regional conference of the International Association of Geomorphologists in Addis Ababa