Page:EB1911 - Volume 27.djvu/437

Rh apex turned towards the north-east, as Africa and America have theirs pointing southward, rose in the middle of what now constitutes Asia. It is only in the outer foldings of the highlands that Palaeozoic fossiliferous deposits are found—Silurian, Devonian, Carboniferous and Permo-Carboniferous. Within that period the principal valleys were excavated, and their lower parts have been filled up subsequently with Jurassic, Cretaceous and Tertiary deposits. One of the most striking instances of this is the very thick Cretaceous and Tertiary deposits which cover the bottom of the valley of the Vakhsh (right tributary of the Amu) and are continued for about 300 m. to the north-east, as far as the Alai valley—probably along the edge of the Pamir plateau. The deposits of the Secondary period have not maintained their horizontal position. While upheavals having a north-eastern strike continued to take place after the Carboniferous epoch, another series of upheavals, having a north-western strike, and occasioned by the expansion of diabases, dolerites, melaphyres and andesites, occurred later, subsequently at least to the close of the Tertiary period, if not also before it, dislocating former chains and raising rocks to the highest levels by the addition of new upheavals to the older ones. Throughout the Triassic and Jurassic periods nearly all Turkestan remained a continent indented by gulfs and lagoons of the south European Triassic and Jurassic sea. Immense fresh-water lakes, in which were deposited layers of plants (now yielding coal), filled up the depressions of the country. Cretaceous and Tertiary deposits occur extensively along the edge of the highlands. Upper and Middle Cretaceous, containing phosphates, gypsum, naphtha, sulphur and alum, attain thicknesses of 2000 and 5000 ft. in Hissar. Representatives of all the Tertiary formations are met with in Turkestan; but while in the highlands the strata are coast-deposits, they assume an open sea character in the lowlands, and their rich fossil fauna furnishes evidence of the gradual shallowing of that sea, until at last, after the Sarmathian period, it became a closed Mediterranean. During the Post-Pliocene period this sea broke up into several parts, united by narrow straits. The connexion of Lake Balkash with the Sea of Aral can hardly be doubted; but this portion of the great sea was the first to be divided. While the Sea of Aral remained in connexion with the Caspian, the desiccation of the Lake Balkash basin, and its break-up into smaller separate basins, were already going on. The Quaternary epoch is represented by vast morainic deposits in the valleys of the Tian-shan. About Khan-Tengri glaciers descended to a level of 6800 ft. above the sea, and discharged into the wide open valleys or syrts. It is most probable that, when allowance has been made for the obliteration of glacial markings, and the region has been better explored, it will appear that the glaciation of Turkestan was on a scale at least as vast as that of the Himalayas. In the lowlands the Aral-Caspian deposits, which it is difficult to separate sharply from the later Tertiary, cover the whole of the area. They contain shells of molluscs now inhabiting the Sea of Aral, and in their petrographical features are exactly like those of the lower Volga. The limits of the Post-Pliocene Aral-Caspian sea have not yet been fully traced. It extended some 200 m. north and more than 90 m. east of the present Aral shores. A narrow strait connected it with Lake Balkash. The Ust-Urt plateau and the Mugojar Mountains prevented it from spreading north-westward, and a narrow channel connected it along the Uzboi with the Caspian, which sent a broad gulf to the east, spread up to the Volga, and was connected by the Manych with the Black Sea basin. Great interest, geological and historical, thus attaches to the recent changes undergone by this basin. Since the theory of geological cataclysms was abandoned, and that of slow modifications of the crust of the earth accepted, new data have been obtained in the Aral-Caspian region to show that the rate of modification after the close of the Glacial period, although still very slow, was faster than had been supposed from the evidence of similar changes now going on in Europe and America. The effects produced by desiccating agencies are beyond all comparison more powerful than those which result from the earthquakes that are so frequent in Turkestan. All along the base of the highlands, from Khojent to Vyernyi, earthquakes are frequent; but their effects lie beyond the scope of our observational methods.

Climate.—The climate of West Turkestan is exceedingly dry and continental. Although the country is approximately comprised within the latitudes of Sicily and Lyons, it has a south Norwegian January and a Persian summer. Temperatures of more than 100° F. in the shade are common, and the heat is rendered still more unbearable by the reflection from a soil destitute of vegetation. The winter is for the most part so cold that the average temperature of January is below the freezing point, and even reaches 0° F. Snow falls for several months on the lower Syr-darya, and, were it not blown away by the winds, sledge-communication would be possible. This river is frozen for an average of 123 days every year in its lower parts and nearly 100 days at Perovsk. At Tashkent there is snow during two months and temperatures of −10° F. have been observed; on the other hand the maximum observation

is 108°. To the south of Khojent the winter becomes more clement. Absence of rain is the distinctive feature of the climate. Although it rains and snows heavily on the mountains, only 11 in. of rain and snow fall throughout the year at Tashkent, at the base of the highlands; and the steppes of the lower Amu have less. A few showers are all that fall from the almost invariably cloudless sky above the Transcaspian steppes.

Fauna.—The fauna of Turkestan belongs to the zoo-geographical domain of northern Asia, and is only differentiated by the presence of species which have disappeared from the peripheral parts of the Old World and now find a refuge in the remotest regions of the uninhabited plateau. From the Palaeoarctic region it is distinguished by the presence of Himalayan species. The distinctive animal of the Pamir plateau is the magnificent Ovis poli (conjectured to be the ancestor of the common sheep). In the alpine tracts of the Tian-shan, on the borders of the Pamir, their horns and skulls are frequently met with, but there the place of the species is now taken by Ovis karelini. The wild horse, which occurred in Poland a few centuries ago, was discovered by Prezhevalsky in the highlands of Dzungaria. The wild camel inhabits the lonely plateaus south of the Ala-shan. The other mammals of Turkestan are mostly those which are met with elsewhere in north Asia. The Himalayan bear (Ursus isabellinus) has its home on the Pamir, and the smaller Leuconyx up to the highest levels on the Tian-shan. Antelopes, Lepus lehmanni, Lagomys rutilus, various species of Arvicolae, and the Himalayan long-tailed marmot (Arctomys caudatus), the most characteristic inhabitant of the alpine meadows, are the only mammals of the Pamir proper. In the alpine region are found the badger (Meles taxus), the ermine (Putorius ermineus) and six other Mustelidae, the wild dog (Canis alpinus), the common and the black-eared fox (C. melanotis), while the corsac fox (C. corsac) is met with only on the plains. Two species of lynx, the cheetah (Felis jubata), F. manul, and F. irbis, must be added to the above. The tiger is met with only on the lower Amu-darya, except when it wanders to the alpine region in pursuit of the maral deer (Cervus maral). The jackal is characteristic of the steppes; it banishes the wolves and foxes. Hares are represented by several species, Lepus lehmanni being the most characteristic. Both the common and the long-tailed marmot (A. baibacinus and A. caudatus) live at the foot of the mountains, as well as four species of Spermophilus, three of voles, two of the mouse and three of the hamster. The Meriones (four species) and the jerboa (five species) are only met with in the steppe region. Of ruminants, beside the sheep (O. poli, O. karelini, O. nigrimontana, O. heinsii), we find one moufflon (Musimon vignei), formerly known only in the Himalayas, the Chinese antelope (Antilope subgutturosa) and the saiga antelope in the steppes, the Siberian ibex and another goat, the yak, the zebu or Indian ox, the common ox, the camel and the dromedary. The wild boar is common in the reed thickets along the rivers and lakes, where it stays during the winter, migrating to the highlands in summer. The hedgehog and porcupine are common in the plains.

No fewer than 385 species of avifauna are recorded, most of them being middle-European and Mediterranean. A large number were formerly known only in the Himalayas, or in Persia, while others have their origin in East Asia. The commonest are mostly European acquaintances. The insect fauna is truly multitudinous. Among the Lepidoptera of the Pamir there is an interesting mixture of Tian-shan with Himalayan species. G. E. Grum-Grshimailo found on the Pamir the butterfly Colias nastes, a species characteristic of Labrador and Lapland; like the alpine plants which bear witness to a Glacial period flora in the Himalayas, this butterfly is a survival of the Glacial period fauna of the Pamir. Of 50 species of molluscs found in Turkestan quite one half are peculiar to the region.

Flora.—As a whole the flora of Turkestan is identical with that of Central Asia, which was formerly continued by geo-botanists as far west as the steppes of Russia, but which must now be considered as a separate region subdivided into two—the Central Asian proper and that of the Gobi. It has its own habitus, notwithstanding the number of species it has in common with Siberia and south-east Russia on the one hand and with the Himalayas on the other, and this habitus is due to the dryness of the climate and the consequent changes undergone by the soil. Towards the end of the Glacial period the Tian-shan Mountains had a flora very like that of northern Caucasia, combining the characteristics of the flora of the European Alps and the flora of the Altai, while the prairies had a flora very much like that of the south Russian steppes. During the Stone Age the human inhabitants lived in forests of maple, white beech and apple trees. But the gradual desiccation of the country resulted