60 ° N. can be assumed, wholesale, as the limit of the two large hydrographic dominions that divide the Russian territory. The sector that extends north of this limit, and which drains to the Arctic Ocean, includes the lower areas of the plateau, because they are below 100 m on average. A selvedge of even more depressed lands fringes it between the mouth of the Mezen ′ and the Urals, divided in two by the emergence of the M. Timan, which extend from the SE. to NO. for over 900 km., with a width of about 80 km.: discontinuous, however, and without apparent connection with the Urals, of which they also form a branch. The crystalline-paleozoic corrugated waves are made up appear worn out by the long, intense erosion (even glacial), the landscape results from escapes of wooded ridges, which rise just over 300 m. at the most (926 m. in the southern edge): but this does not mean that they stand out less on the flat uniformity of the plane on which they stand. In this, the E. dei Timan region (Tundra Bol′šezemel′skaja) is also morphologically more varied, due to the presence of small isolated reliefs and more abundant glacial traces.
Genetically different is the sector that falls within the borders of Russia to the West of the White Sea: both the squat peninsula of Kola and Karelia, which is its southern continuation (beyond the Bay of Kandalakša), constitute a strip of the Fenno-Scandic region., of which they reproduce the characters. The large granite-gneissicoscistosa audience is presented here, as in Finland, smooth, sparse moraine embankments and cribrata of glacial cavities filled with lakes (small and medium lakes occupy 1 / 20of the surface of the entire Kola Peninsula); of these the largest (Lake Ladoga, Lake Onega) occur in contact between the region itself and the north-western limit of the Sarmatic plain. In general, the relief is not very pronounced here either; however in the Kola peninsula it reaches 1240 m. and the moraine lining itself assumes varieties and movements that are not found on the other side of the White Sea.
According to Transporthint, the central zone of the Russian region essentially corresponds to the dominion of the upper and middle Volga, between the Valdai shelf and the Uralic relief; large dissymmetrical basin, inclined in complex towards E., and actually constituted by an alternation of raised strips with more or less wide depressed edges. In addition to the tectonic accidents mentioned above, the alternation must be placed in relation with the oscillations of the Quaternary glacial apparatuses: where these, withdrawn, accumulated the transported materials, alignments of moraine bumps were formed, beyond which the waters of pressure they cut their furrows and spread sand deposits. However, the passage from one to the other of the river basins that divide the region is often barely noticeable: in the same Valdai which, although they act as a watershed between three seas (Arctic Ocean, Baltic, Caspian), the landscape maintains the soft and indecisive lines typical of the plateau: the maximum heights, which reach 322 m. in Kamestik, they slightly overlook the humble expanse of peat bogs, marshes and lakes that find their place between the arches drawn by the moraines.
Although its absolute height is modest, this detected mass continues in any case fairly compact towards the S., separating the Oka basin, a tributary of the Volga, from that of the Dnieper, it does not touch, beyond 55 ° N., from the glaciers Pleistocene, which he managed to arrest. The front assumed by these in their maximum expansion towards S. however exceeded the 50 ° in correspondence to the low courses of the Dnieper and the Don, to recede almost parallel to the middle Volga and the Kama. A function similar to that of the central shelf had, in front of the extension of the great Quaternary glacier, the two raised masses that flank it to the West (podolic rialto) and to the East. del Dnestr, Bug and Dnieper, belongs to the crystalline-granite block of Ukraine (the granite-gneissic basement, corrugated and disturbed in the precambric period, it bears horizontal and sub-horizontal piles of schists and siluric-devonic limestones and even more powerful deposits of cretaceous and tertiary marl, covered in turn by löss); the second, much more varied in its geological constitution (from the bibulous Permian gypsum through the Jurassic sands and marls, to the Paleozoic sandstones, surmounted by more or less thick layers of black earth), is much less compact and continuous, dismembered as it is by the dense network of the tributaries of the Volga (especially in the sector between it and its tributary Sura). The maximum heights, however, do not differ much in the two elevations: 373 m. in Podolia, 396 m. not far from Saratov, on the middle Volga. The central ridge remains significantly below this figure (296 m. To E. of Kursk), but its average height is greater, which does not fail to influence the communications between the Dnieper and Oka valleys and of the high Don. Similarly to the Volga, which runs along the eastern edge of the hills of the same name, the course of the Dnepr laps the podolic block on the same side and the Don and Oka blocks the central shelf. The symmetry is all the more perfect, as the areas upstream of the three depressions also represent the flattest and flatter areas: Polesia, Moscow, Ryazan ′, Tambov basins and the Volga region from Yaroslavl ′ to Kazan ′, proceeding from W to E. The course of the Donec marks the limit of the central block in the S. between the Donets and the Black Sea,
