Page:Encyclopædia Britannica, Ninth Edition, v. 21.djvu/91

Rh SOIL AND CLIMATE.] K U S S I A 75 motion of the boulders. Its southern limits, roughly correspond- ing with those established by Murchison, but not yet settled in the south-east and east, are, according to M. Nikitin, the following : from the southern frontier of Poland to Ovrutch, Umaii, Kremen- tclmg, Poitava. and Razdornaya (50 N. latitude), with a curve northwards to Kozelsk (1) ; thence due north to Vetluga (58 north latitude), east to Glazova in Vyatka, and from this place towards the north and west along the watershed of the Volga and Petchora (?). South of the 50th parallel appears the loess, with all its usual characters (land fossils, want of stratification, &c. ), showing a re- markable uniformity of composition over very large surfaces; it covers both watersheds and valleys, but chiefly the former. Such being the characters of the Quaternary deposits in Russia, the majority of Russian geologists now adopt the opinion that Russia was covered, as far as the above limits, with an immense ice-sheet which crept over central Russia and central Germany from Scandi- navia and north Russia. Another ice-covering was probably ad- vancing at the same time from the north-east, that is, from the northern part of the Urals, but the question as to the glaciation of the Urals still remains open. As to the loess, the view is more and more gaining ground which considers it as a steppe-deposit due to the drifting of fine sand and dust during a dry episode in the Pleistocene period. The deposits of the Post-Glacial period are represented through- out Russia, Poland, and Finland, as also throughout Siberia and central Asia, by very thick lacustrine deposits, which show that, after the melting of the ice-sheet, the country was covered with immense lakes, connected by broad channels (the fjarden of the Swedes), which later on gave rise to the actual rivers. On the outskirts of the lacustrine region, closely resembling the area of the actual continent, traces of marine deposits, not higher than 200 or perhaps even 150 feet above present sea-level, are found alike on the Arctic Sea and on the Baltic and Black Sea coasts. A deep gulf of the Arctic Sea advanced up the valley of the Dwina ; and the Caspian, connected by the Manytch with the Black Sea, and by the Uzboy valley with Lake Aral, penetrated north up the Volga valley, as far as its Samara bend. Unmistakable traces show that, while during the Glacial period Russia had an arctic flora and fauna, the climate of the Lacustrine period was more genial than it is now, and a dense human population at that time peopled the shores of the numberless lakes. The Lacustrine period has not yet reached its close in Russia. Finland and the north-west hilly plateaus are still in the same geological phase, and are dotted with numberless lakes and ponds, while the rivers continue to dig out their yet undetermined chan- nels. But the great lakes which covered the country during the Lacustrine period have disappeared, leaving behind them immense marshes like those of the Pripet and in the north-east. The disappearance of what still remains of them is accelerated not only by the general decrease of moisture, but also by the gradual up- heaval of northern Russia, which is going on from Esthonia and Finland to the Kola peninsula and Nova Zembla, at an average rate of about two feet per century. This upheaval, the consequences of which have been felt even within the historic period, by the drain- age of the formerly impracticable marshes of Novgorod and at the head of the Gulf of Finland, together with the destruction of forests, which must be considered, however, as a quite secondary and subordinate cause, contributes towards a decrease of precipi- tation over Russia and towards increased shallowness of her rivers. At the same time, as the gradients of the rivers are gradually in- creasing on account of the upheaval of the continent, the rivers dig their channels deeper and deeper. Consequently central and especially southern Russia witness the formation of numerous miniature canons, or ovraglii (deep ravines), the summits of which rapidly advance and ramify in the loose surface deposits. As for the southern steppes, their desiccation, the consequence of the above causes, is in rapid progress. 1 The soil of Russia depends chiefly on the distribution of the boulder-clay and loess coverings described above, on the progress made by the rivers in the excavation of their valleys, and on the moistness of climate. Vast areas in Russia are quite unfit for cultivation, 27 per cent, of the aggregate surface of European Russia (apart from Poland and Finland) being occupied by lakes, marshes, sands, &c., 38 per cent, by forests, 14 per cent, by prairies, and only 21 per cent, being under culture. The distri- bution of all these is, however, very unequal, and the five follow- ing subdivisions may be established : (1) the tundras ; (2) the forest region ; (3) the middle region, comprising the surface avail- able for agriculture and partly covered with forests ; (4) the black- earth (teJtcrnoziom) region; and (5) the Steppes. Of these the black-earth region, about 150, 000, 000 acres, which reaches from the Carpathians to the Urals, extending to the Pinsk marshes and 1 Bibliography. Memoirs, Izvestia. and Geological Maps of the Committee for the Geological Surrey of Russia ; Memoirs and Sborni/cs of the Hineralogical Society, of the Academy of Science, find of the Societies of Naturalists at the Universities; Mining Journal; Murchison's Geology of Russia; Helmersen's and Mollei-'s Geological Maps of Russia and the Urals; Inostrantseff in Appendix to Russian translation of lieclus's Geogr. Univ.. and Manual of Geology (Russian). the upper Oka in the north, is the most important. It is covered with a thick sheet of black earth, a kind of loess, mixed with 5 to 15 per cent, of humus, due to the decomposition of an herba- ceous vegetation, which developed richly during the Lacustrine period on a continent relatively dry even at that epoch. On the three-fields system corn has been grown upon it for fifty to seventy consecutive years without manure. Isolated black-earth islands, less fertile of course, occur also in Conrland and Kovno, in the Oka, Volga, and Kama depression, on the slopes of the Urals, and in a few patches in the north. Towards the Black Sea coast its thickness diminishes, and it disappears in the valleys. In the extensive region'covered with boulder-clay the black earth appears only in isolated places, and the soil consists for the most part of a sandy clay, containing a much smaller admixture of humus. There culture is possible only with the aid of a considerable quantity of manure. Drainage finding no outlet through the thick clay cover- ing, the soil of the forest region is often covered with extensive marshes, and the forests themselves are often mere thickets spread- ing over marshy ground ; large tracts covered with sand appear in, the west, and the admixture of boulders with the clay in the north-west renders agriculture increasingly difficult. On the Arctic coast the forests disappear, giving place to the tundras. Finally, in the south-east, towards the Caspian, on the slopes of the southern Urals and the Obshchiy Syrt, as also in the interior of the Crimea, and in several parts of Bessarabia, there are large tracts of real desert, covered with coarse sand and devoid of vegetation. 2 Notwithstanding the fact that Russia extends from north to south through 26 degrees of latitude, the climate of its different Climate, portions, apart from the Crimea and the Caucasus, presents a striking uniformity. The aerial currents cyclones, anti-cyclones, and dry south-east winds extend over wide surfaces and cross the flat plains freely. Everywhere we find a cold winter and a hot summer, both varying in their duration, but differing rela- tively little in the extremes of temperature recorded. From Table III. (page 76) it will be seen that there is no place in Russia, Archangel and Astrakhan included, where the thermometer does not rise in summer nearly to 86 Fahr. and descend in winter to - 13 and - 22. It is only on the Black Sea coast that we find the absolute range of temperature reduced to 108, while in the remainder of Russia it reaches 126 to 144, the oscillations being between - 22 to - 31, occasionally - 54, and 86 to 104, occasion- ally, 109. Everywhere the rainfall is small : if Finland and Poland on the one hand and Caucasus with the Caspian depression on the other be excluded, the average yearly rainfall varies between the limits of 16 and 28 inches. Everywhere, too, we find that the maximum rainfall does not take place in winter (as in western Europe) but in summer, and that the months of advanced spring are warmer than the corresponding months of autumn. Though thus exhibiting all the distinctive features of a con- tinental climate, Russia is not altogether exempt from the moder- ating influence of the ocean. The Atlantic cyclones also reach the Russian plains, mitigating to some extent the cold of the winter, and in summer bringing with them their moist winds and thunderstorms ; their influence is chiefly felt in western Russia, but extends also towards and beyond the Urals. They thus check the'extension and limit the duration of the cold anticyclones. Throughout Russia the winter is of long continuance. The last days of frost are experienced for the most part in April, but also in May to the north of 55. The spring is exceptionally beautiful in central Russia ; late as it usually is, it sets in with vigour, and vegetation develops with a rapidity which gives to this season in Russia a special charm, unknown in warmer climates ; the rapid melting of snow at the same time raises the rivers, and renders a great many minor streams navigable for a few weeks. But a return of cold weather, injurious to vegetation, is observed throughout central and eastern Russia between May 18 and 24, so that it is only in June that warm weather sets in definitely, reaching its maximum in the first half of July (or of August on the Black Sea coast). The summer is much warmer than might be supposed ; in south-eastern Russia it is much warmer than in the corresponding latitudes of France, and really hot weather is experienced everywhere. It does not, however, prevail for long, and in the first half of September the first frosts begin to be experienced on the middle Urals ; they reach western and southern Russia in the first days of October, and are felt on the Caucasus about the middle of November. The temperature descends so rapidly that a month later, about October 10 on the middle Urals and November 15 throughout Russia^ the thermometer ceases to rise above the freezing-point. The rivers rapidly freeze ; towards November 20 all the streams of the White Sea basin are covered with ice, and so remain for an average of 167 days ; those of the Baltic, Black Sea, and Caspian basins freeze later, but about December 20 nearly all the rivers of the 2 Bibliography. Ruprecht, Geo.-Botanical Researches on the Tchernoziom; Dofcutchaeff, Russian Tchernoziom, 1880; Id., Phys. Chem. Researches ; Materials for Statistics of Russia, published by the Minister of Domains, v., 1871; Wasil- tchikoff, "Tchernoziom and its Future," in Mem. Moscoic Soc. ofAgr., 1877.