Asia, the largest of the divisions of the world, occupies the northern portion of the eastern hemisphere in the form of a massive continent which extends beyond the Arctic circle, and by its southern peninsulas nearly reaches the equator. The origin of its name remains unknown. Herodotus failed to explain it; modern philology has also failed. It appears, however, most probable—the first elements of our geographical terminology having originated in Greece—that Asia was a local name given to the plains of Ephesus, and that this name was gradually extended to the Anatolian peninsula, and later on to the whole of the continent.
Viewed in their broad features, Europe and Asia constitute but one continent, extending from west to east, and having the shape of an immense triangle, the angles of which are Spain in the west, the peninsula of the Tchukchis in the north-east, and that of Malacca in the south-east. The Arctic Ocean in the north, the Pacific in the east, and the Indian Ocean, continued by its narrow gulf, the Red Sea, which nearly reaches the Mediterranean, inclose the continent of Asia. This immense mass of land touches the latitude of in Cape Tchelyuskin, while Cape Burros, at the extremity of the peninsula of Malacca, and 5350 miles distant from the former, falls short by of reaching the equator. Cape Baba, in Asia Minor, advances as far west as the 26th degree of longitude, and the utmost NE. extremity of Asia—East Cape, 5990 miles distant from Cape Baba—protrudes to the 190th degree (12 hours 40 minutes) to the east of Greenwich. The area covered by Asia and its islands is 17,255,890 sq. m.; that is, almost exactly one-third of the land-surface of the globe (32 per cent.). It is a seventh larger than the surface of both Americas together, by one-half larger than that of Africa, and more than four times larger than that of Europe.
Boundaries.—Neither by its geographical features nor by its climate, vegetation, and animals, still less by the ethnographical features of its inhabitants and their history, can Asia be sharply separated from Europe. The physical features of both continents show a manifold interdependence; and however pronounced the individuality of Europe in the west, it melts into Asia in its eastern parts; while throughout its history Europe has been influenced by Asia in a thousand ways. Our races have been mixed with those of Asia; in Asia our civilisation, our religions, our political and social institutions have had their origin; and ever since Europe made an independent start in history, it has never ceased to feel the influence of Asia. Geographically speaking, Europe is a mere appendix to Asia, and no exact geographical delimitation of the two continents is possible. The low Urals are not even an administrative frontier: European Russia extends over their eastern slope. Farther south, the dry steppes of Asia penetrate into Europe and pass indistinguishably into the prairies of Russia. Caucasus is surely Asiatic in character; but, to separate it from Europe, one must resort to the old dried-up channel of the two Manytch rivers, which at a geologically recent epoch connected the Black Sea with the Caspian. As to Asia Minor—also purely Asiatic in structure and inhabitants—it so closely approaches Europe that the Sea of Marmora and its narrow river-like straits seem almost an artificial boundary, while the islands surrounding Asia Minor mingle with those which continue Greece to the east, and the Anatolian plateau seems to be continued in the Balkan Peninsula.
The line of separation from Africa is better defined by the narrow Red Sea. But Arabia participates so largely in the physical features of Africa that it is in a sense intermediate between the two continents.
In the south-east, the numberless islands of the Dutch Indies—relics of a sunken continent—appear as a bridge towards Australia; and although a boundary between Australia and Asia has been drawn through the Timor Sea, or rather between the islands Bali and Lombok, in the Sunda Archipelago, still it is a boundary only in a limited sense: it only separates two faunas.
In the extreme north-east, Asia sends out a peninsula to meet one of the Alaskan peninsulas in America, from which it is separated only by a shallow and narrow channel, Behring Strait. Plants, animals, and men freely migrated over this ferry; while the geographer sees in the two peninsulas a line of connection between the two great plateaus of the Old and New World.
Peninsulas.—Although the coasts of Asia are much more indented by gulfs and peninsulas than those of Africa or America, still it stands in this respect much behind Europe, and has 1 mile of coast-line for every 337 sq. m. of its area, that is, three times less than Europe; besides, about one-fifth of its shores is washed by the ice-bound Arctic Ocean (9900 miles out of 51,000), or by the foggy and icy sea of Okhotsk, where navigation is possible only for a few months, or even weeks, in each year. Its peninsulas comprise nearly one-fifth of its surface (19 per cent., as against 28 in Europe), but they partake of the massive structure of the continent: they are massive too, and, as a rule, little indented. Three immense offsets continue the continent of Asia into more tropical latitudes—Arabia, India, and the Indo-Chinese Peninsula—and some likeness exists between them and the three southern peninsulas of Europe—Spain, Italy, and the Balkan Peninsula, surrounded by its archipelago of hundreds of islands. Asia Minor protrudes between the Black Sea and the Mediterranean as a huge mass of tableland broken by narrow gulfs in its western parts. In the Pacific there are only three large peninsulas—Corea, Kamchatka, and that of the Tchukchis—the whole of the Pacific coast having the shape of wide curves turning their convexity to the sea, and indented by but a few gulfs. The flat, ever frozen, uninhabitable peninsulas of the Arctic Ocean, Taimyr and Yalmal, could play no part in the growth of civilisation.
Seas, Coasts.—The early inhabitants of Asia had no Mediterranean Sea to serve as a highway of communication between the southern peninsulas. The gulfs which separate them—the Arabian Sea and the Bay of Bengal—are wide, open divisions of the Indian Ocean. The narrow, elongated Red Sea penetrates between the dry, stony, and barren lands of Africa and Arabia; and only now, since it has been brought into communication with the Mediterranean by the Suez Canal, has it become an important channel of traffic. The Persian Gulf, inclosed between the deserts of Arabia and the mountains of Persia, is bordered by regions scarcely inhabited. Asia's true Mediterranean is on the east, where several archipelagoes, like so many chains of islands, mark off from the ocean the Southern and Eastern China Seas, whose Gulfs of Siam and Tonkin, and especially the Yellow Sea with the Gulf of Pechili, penetrate into the continent. Those gulfs, since the dawn of history, have promoted the development of marine traffic in these regions, and would have done so still more but for the dreadful typhoons, the constant danger of these seas. The Sea of Japan is less favoured by climate and currents, and it has on its west the inhospitable coasts of Northern Manchuria, where Russia is trying to establish a maritime centre at Peter the Great Bay. The Sea of Okhotsk and that of Behring, although possessing fine gulfs (Ghizhiga, Anadyr), have no importance for the maritime traffic of nations. Still less the Arctic Ocean, with its wide estuaries and bays, and the Kara Sea, through which ships find a passage amidst the broken ice-crust for only a few weeks in the year.
Islands.—The islands of Asia are very numerous, and cover an aggregate of no less than 1,023,000 sq. m. (nearly 6 per cent. of Asia's surface). The coasts of Asia Minor are dotted with islands, of which the Sporades connect it with Greece. Cyprus was, from remote antiquity, a centre of civilisation; so also Ceylon. The Laccadives and Maldives are mere coral atolls, rising amidst the Indian Ocean, and sheltering some 200,000 inhabitants. The islands of East Asia are much more important. A narrow strip of islands, some large like Sumatra (177,000 sq. m.) and Java, others mere reefs, extend in a wide semicircle, under the name of Andaman and Sunda Islands, from Burmah to Australia, separating the Indian Ocean from the shallow Java Sea and the Malay Archipelago. This last—an immense volcanic region inhabited by the Malay race—comprises the huge Borneo, the ramified Celebes, and the numberless small islands of the Moluccas, the Philippines, &c., connected on the north-west with the Chinese coast by the island of Formosa. This latter, as well as Hainan, may be properly considered as part of the Chinese mainland. The Loo-choo (Liu-kiu) Islands and the Japanese Archipelago, the latter joining Kamchatka by the Kuriles, continue farther NE. this chain of islands which border the coasts of Asia. Sakhalin is so closely situated to the continent that it was long regarded as a peninsula. In the Arctic Ocean, the small Bear Islands, the archipelago of the Liakhof, Anjou, and De Long Islands, as also those of the Kara Sea, are lost amidst ice-fields, and are but occasionally visited by whalers. Kellett's, or Wrangel's Land, off the peninsula of the Tchuktchis, has been merely sighted, not yet visited.
Orography.—Asia is at once the largest and the highest of all continents. Not only has it a number of mountains which exceed by five and six thousand feet the loftiest summits of the Andes; it has also the highest and the most extensive plateaus. If the whole mass of its mountains and plateaus were uniformly spread over its surface, the continent would rise no less than 2885 feet above the sea, while Africa and North America would respectively reach only 2165 and 1950 feet.
High plateaus are the predominant feature of Asia's orographical structure; they occupy nearly two-fifths of its area. One of them—that of Western Asia, including Anatolia, Armenia, and Iran—extends in a south-easterly direction from the Black Sea to the valley of the Indus; while the other—the high plateau of Eastern Asia, still loftier and much more extensive—stretches NE. from the Himalayas to the north-eastern extremity of Asia, resembling in shape a South America pointing NE., and meeting at Behring Strait the north-western extremity of the high plateau of North America. These vast regions, mostly unfit for agriculture and human settlement, poorly watered over wide areas, and assuming there the character of dry deserts, divide Asia into two parts—the lowlands of Siberia and the Aral-Caspian depression to the north of the plateau-girdle, and the lowlands of Mesopotamia, India, and China to the south. These could enter into only occasional communication across the thinly peopled plateaus, and they have followed quite independent lines of development. The southern lowlands are themselves separated into three distinct parts, which have developed independently, without enjoying that continuous mutual intercourse which constitutes the distinctive feature of European civilisation.
(1) Plateau of Eastern Asia.—The high plateau of Eastern Asia, which stretches for 4500 miles to the NE. from the Himalayas, occupies more than one-fifth of the superficies of Asia. Its surface is not quite flat, as the rather inappropriate orographical name of 'plateau' might suggest. It has its depressions; it has also on its north-western borders several broad trenches which are cut in its mass, like gigantic railway-trenches leading with an imperceptible gradient from the lowlands to the heights of the plateau. For many consecutive geological periods these trenches were either channels for the drainage of the waters discharged by the plateau, or else gulfs of the seas which surrounded it, so that now their banks, water and glacier worn, appear like chains of mountains to the traveller who follows their flat bottoms. The plateau has also mountain-ridges rising several thousand feet above its surface, and high border-ridges. But its depressions do not sink to the level of the lowlands, their lowest parts being still two or three thousand feet above the sea; while the chains of mountains, although rising to high absolute altitudes, are still relatively low, their bases on the plateau being at a level of several thousand feet above the sea. They do not display the diversified aspect usually characteristic of alpine regions intersected by deep fertile valleys; and unvaried monotony—monotony of orographical features, climate, flora, and fauna—remains the distinctive feature of the plateau over immense distances. For thousands of miles the traveller finds the same broad and open valleys, the same harsh climate, the same species of plants and animals, the same unfitness for agriculture.
The highest parts of the East Asian plateau are in Tibet, where it has a width of 1600 miles from west to east, and an average height of from 10,000 to 17,000 feet (sometimes said to be equal to that of the summit of Mont Blanc; see TIBET), and only cattle-breeding is possible in these high, cold, dry valleys. The highest plateau of the earth is girdled by the highest chain of mountains, the Himalayas—a typical 'border-ridge' which has one foot on the high plateau, and the other in valleys ten to fifteen thousand feet deeper, where the palm and vine grow freely. This immense chain of snow-clad peaks, which in Europe would reach from Gibraltar to Greece, raises its lofty summits above 20,000 feet; its lowest passes are 15,000 feet high, and Gaurisankar or Mount Everest—the highest mountain of the globe—has its snow-cap at a height of 29,000 feet, that is, 5½ miles above the sea. A series of chains separated from the Himalayas by high longitudinal valleys run parallel to them in the north, and of these, the Karakorum Mountains rise high above the snow-line; their loftiest peak, the Dapsang, is 28,700 feet high. In the east, the plateau of Tibet is bordered by the snow-clad mountains through which the great rivers of China, Burmah, and
Siam find their way to the lowlands. They are still very little known.
In the north-west, the Tibet plateau joins another much smaller, but very high plateau—that of Pamir ('the roof of the world'), which covers an area of 37,000 sq. m. Several chains of mountains running NE. diversify its surface, but still the travellers crossing it need not descend to a level lower than from 10,000 to 11,000 feet until they have crossed its northern border-ridge, the Alai Mountains, whose peak Kaufmann (22,500 feet) exceeds twice the highest summit of the Pyrenees. The Tagarma peak, in Eastern Pamir, reaches a height of 25,800 feet. Farther north and north-east of the Pamir, a wide, intricate complex of several high chains, running mostly from WSW. to ENE., with several ridges shooting from them to the NW., covers an aggregate area nearly as large as Germany. These mountains are known under the general name of Tian-shan (q.v.). The great Khan-tengri rises there to 24,000 feet, and most of the Tian-shan ridges are snow-clad; even the outer ridges raise their summits to fifteen or sixteen thousand feet—that is, above the upper limits of tree vegetation, while some of their deep, fertile valleys have been transformed into veritable gardens and granaries by means of irrigation.
(2) Central Asian Depression.—In the north, the plateau of Tibet is bordered by a succession of lofty chains (Kuen-lun, Altyn-tagh, Nañ-shan), reaching more than 20,000 feet in their highest parts. These chains separate it from the great central depression which is occupied by Eastern Turkestan in the west, and by the Desert of Gobi in the east. This great depression—including the Han-hai, or 'dried-up sea,' of the basin of the Tarim—must be considered, however, only as a lower terrace of the great plateau of Eastern Asia. It has an altitude of from 3000 to 4000 feet in the west, and 2200 feet in its lowest part—the depression of Lake Lob-nor. It has no outlet to the sea—not even to Lake Aral or the Caspian; the winds which might bring the moisture of the ocean are deprived of it in crossing the higher plateaus and border-ridges which surround it, and this immense bottom of an immense interior sea is rapidly drying up. All through the historical period it has continued to dry up, till Lob-nor, which covers an area four times as large as that of the Lake of Geneva, has become now but a wide marsh, with a maximum depth of some 15 feet—a small remnant of a much larger sea which existed at the dawn of history, and in whose rapid desiccation we probably must look for one of the causes which impelled the Huns and the Mongols to their great migrations towards the west. Human settlements, secluded from the rest of the continent, and rarely visited now by a few caravans, are scattered only in the upper parts of the tributaries of the Tarim, where the water of few and scanty rivers may maintain life; but they were much more numerous before, as is testified by ruins of great cities, now buried under the drifting sands. In the Eastern Gobi, where the SE. monsoons of the Pacific during the summer and the NW. winds from Siberia during the winter still bring some moisture, the gravelly soil is covered with grass for a few months each year; but in the west, man must sustain a hard struggle against the moving sands raised by storms in the air, more dreaded than the worst snow-storms of the far north. In the south-east, towards the chains of Ala-shan and In-shan, the wild horse and the wild camel—ancestors of our domesticated breeds—find their last refuge on lonely pastures scarcely ever visited by man.
(3) Northern Part of the Great Plateau.—The dry and barren ridge called Eastern Tian-shan, and two other ridges running NW., separate the Han-hai depression of Central Asia from the trenches of Urumtsi and Urungu, which descend west to the lowlands of Siberia towards Lakes Balkhash and Zaisan. Beyond the great depression the plateau rises again, and reaches an average height of from 4000 to more than 5000 feet in the upper parts of the Yenisei and Selenga, and about 2000 feet in its lowest part—the small depression of Lake Ubsa-nor. The Ektagh (or Great Altai) in the west, the Khangai and the Yablonovoi ridge farther east, separate this upper terrace of the plateau from the lower terrace of Eastern Turkestan and Gobi. It would seem that the Yablonovoi ridge is continued farther SW. by a succession of ridges which probably join the Tianshan Pelau (Eastern Tian-shan), and which separate the higher Siberian terrace of the plateaus from the lower terrace of the Gobi. This last has in the east its border-ridge—the Great Khingan (6000 to 8000 feet)—which is a continuation of the mountains of the middle Hoang-ho; it is pierced by the Amur below Albazin, and in the north-east joins the Stanovoi or Okhotsk coast-ridge. See SIBERIA.
In the north-west, the plateau is bordered by the snow-clad Sailughem ridge of the Altai (8000 to 9000 feet), which appears as a continuation of the Tian-shan and the Ala-tau, and which is continued farther NE. by the West Sayans. A wide indentation, however, occupied in its deepest parts by Lake Baikal (and very much like the indentation made by the Caspian in the plateau of Western Asia), breaks the continuity of the border-ridge. This last reappears again in the east of the Siberian lake as a huge wall, known under the names of Khamar-daban, Barguzin, Muya, and Tchara mountains. They rise from 6000 to 8000 feet above the sea, reaching the snow-line only in the Munku-Sardyik (11,900 feet), and presenting their steepest slopes towards Siberia, while their inner base lies on a plateau 3500 to 4500 feet high. This immense wall is pierced by the broad trench-like valleys of the Selenga and its tributary the Uda, which are respectively the two great highways from Lake Baikal to Mongolia and the Upper Amur. A broad zone of alpine tracts more than 150 miles wide and 2000 miles long—the Altai, the Kuznetskiy Ala-tau, the Baikal, Lena, Olekma, and Vitim mountains—fringes this plateau in the west, from Lake Zaisan to the far north-east of Siberia. It consists of a series of short chains, mostly running NE., with numerous spurs, and intersected by deep and narrow valleys, clothed with forests and rich in auriferous deposits. A like succession of alpine tracts, although narrower, follows the south-east edge of the plateau in China and Manchuria. As to the plateau itself—whose surface is diversified by several chains rising above its level—its broad, flat, and open valleys, unfit for agriculture in consequence of their altitude, have none of the dryness of the plateau of Tibet. They are covered with a rich grass-vegetation, and are frequented by shepherds; while the slopes of the hills, thickly clothed with forests, are rich hunting-grounds. Farther north—in the Vitim plateau, the Utchur, &c.—the surface becomes very marshy, and the vegetation still poorer; its height does not now exceed 3500 feet, and it becomes narrower. Its north-eastern extremity—the abode of the Tchuktchis—is but very little known.
(4) The Plateau of Western Asia.—Several parallel chains of mountains, reaching 24,000 feet in their highest parts, and running NE. to SW.—the Hindu-Kush and its parallel chains—connect the great plateau of Eastern with that of Western Asia, which may be subdivided into three parts: Iran, Armenia, and Asia Minor. The plateau of Iran (425,000 sq. m.) is bordered in the north-east by the border-ridges of the Paropamisus, the Kopet-dagh, which presents its steep, stony slopes to the Turcoman Steppes, and the Elburz (with its peak Demavend, 20,100 feet high), which describes a curve around the South Caspian shore; in the east it is fringed by several snow-clad chains, which separate the stony plateaus of Afghanistan and Beluchistan from the fertile valley of the Indus; and in the south-west it falls by several steep terraces towards the Persian Gulf and its continuation—the valley of the Tigris and Euphrates. The lowest parts of the Iran plateau, in the valley of the Helmand, which discharges its water into the rapidly desiccating Lake Hamun, are 3500 feet above the sea, and although fertile in the south-east, it assumes the character of a wide salt-desert towards the Caspian Sea. There it joins the plateau of Armenia, bounded on the north by the Anti-Caucasus, and in the south by the Kurdistan Mountains. The great salt lakes Van and Urmia have their levels at altitudes of more than 5000 feet; and Mount Ararat, which rises on the plateau, reaches a height of 16,969 feet. Farther west, the plateau of Armenia meets that of Asia Minor, all three together making a wide plateau, elongated towards the north-west, and having a length of 2700 miles, and a width of from 700 to 180 miles. Several chains of mountains running NE. and NW., and reaching more than 10,000 feet in their loftiest summits, intersect the plateau of Asia Minor, which is bordered by the Taurus Mountains on its Mediterranean coasts, and the Pontic Mountains on the Black Sea shore.
(5) Separate Chains of Mountains.—The hilly tracts of Asia are not confined to the plateaus and their border-ridges. The Caucasus, an immense wall of snow-clad mountains, stretches NW. to SE. for nearly 800 miles along the border of the Armenian plateau, from which it is separated by the broad valley of the Kura. It reaches 18,560 feet in the Elborus (Elburz) peak. The Urals, from 2000 to 4000 feet high, which separate Europe from Asia, are a broad belt of hilly tracts, stretching as a whole from north to south. Farther east, the Karatau and the Tarbagatai, as also the Verkhoiansk ridge in the far north, strike off from the alpine tracts which fringe the plateau, and have a direction perpendicular to them; while the Byrranga hills diversify the monotony of the tundras of the Taimyr Peninsula. The Yeniseisk Mountains, consisting of several chains running SW. to NE., contain rich treasures of gold-dust. Several chains, little known, and some of them volcanic, fill up the peninsula of Kamchatka. A number of parallel chains, 5000 to 7000 feet high—the Ilkhuri-alin, the Bureya Mountains, Pribrezhnyi, and Tartar—run from the Gulf of Pechili to the Sea of Okhotsk, and are continued in Sakhalin Island; while other chains having the same direction form an outer submarine wall of Asia in Corea, the Japan Archipelago, and the Kuriles. The Nan-ling, Tayu-ling, and other smaller chains having also the same north-eastern direction, cross South China; and submarine chains belonging to the same system of parallel plaitings of the earth-crust are seen in the islands of Formosa and Loo-choo (Liu-kiu). The Seravak chain of Borneo, continued NE. in the Palawan Islands, as also the mountains of Celebes, have the same direction; while the mountains of Sumatra and Malacca assume the perpendicular north-western direction which prevails in South-western Asia. A range of lofty volcanoes rises steeply from the very depths of the ocean in the islands of the Java Sea. The real orography of Bunnah and Siam is yet hardly known.
The interior of the Indian peninsula is again occupied by the wide plateau of the Deccan, having an average height of from 1500 to 3000 feet, bordered in the west by the Western Ghats (7870 feet high in Nila Ghiri peak) and the Cardaman Mountains, and in the east by the much lower and broader Eastern Ghats. The Pedrotallagalla peak in Ceylon rises 8330 feet high. The immense plateaus of Arabia, covered with sand-deserts interspersed with a few fertile regions, rise to altitudes of from 3500 to 4500 feet, and are intersected by several little-known chains of hills. Their south-eastern border-ridge—the Hadramaut—reaches nearly 7000 feet in its highest summits, and the north-western border-ridges—the Lebanon and Anti-Lebanon—have summits nearly 10,000 feet high; while in the deep valley of the Jordan the Dead Sea is sunk to a level of 1185 feet below that of the ocean.
(6) Lowlands, Plains.—The whole of North-western Asia is occupied by an immense lowland—Siberia—which joins in the south the wide Aral-Caspian depression. This lowland, whose level is less than five or six hundred feet, does not reach the outer borders of the above-mentioned alpine regions which fringe the great plateau of East Asia. It is separated from them by a belt of elevated, undulating plains rising to a level of from 1000 to 1500 feet, the limits of which may be roughly indicated by a line traced from Merv to Tomsk, and thence to Verkhoiansk. These plains, which assume the character of dry steppes towards the south, are as a whole highly suitable for agriculture and cattle-breeding. Not so the lowlands proper, which bear unmistakable traces of having emerged from the sea during the Post-Pliocene period. In the Aral-Caspian depression they often have the character of sandy deserts, and can be cultivated only where there is a belt of fertile Loess (q.v.) at the base of the mountains, and the streams issuing from the hilly regions yield sufficient water for irrigation. On the northern coast of the Caspian, the Aral-Caspian depression descends even below the level of the sea; while the dry plateau of Ust Urt rises to an average height of about 1000 feet above the sea. The southern parts of Western Siberia are a perfect granary, and are rapidly being colonised; but beyond the 56th or 57th degrees of latitude, the lowland assumes the character of marshy forests, almost totally unsuitable for settlements; and farther north, that of a treeless, barren, and ever-frozen tundra. A like belt of elevated plains, succeeded by one of lowland, runs along the great plateau on its south-eastern edge; and those parts of the plains which are covered in China with loess, as also those of Manchuria to the west of the Pribrezhnyi ridge, are the abodes of a dense agricultural population. In the Indo-Chinese Peninsula, the lowlands are limited to Tonkin, Cambodia, and the lower Menam and Irawadi, where they are fertile, but often marshy.
The wide space between the great plateaus of Western and Eastern Asia and that of the Deccan, watered by the Indus and the Ganges, is again an immense lowland, covering no less than 400,000 sq. m., and supplying the means of existence to 125 millions of inhabitants. Its western part suffers much from want of irrigation; but artificial canalisation rapidly conquers the desert (see INDIA). Another wide lowland, Mesopotamia, or the broad valley of the Tigris and Euphrates, was a cradle of civilisation from the remotest antiquity. Finally, the fertile lowlands in the north of the Caucasus are being rapidly colonised by Russian agriculturists.
Rivers.—It is easy to perceive from the above rapid sketch how much the orographical structure of Asia favours the development of very great rivers, whose drainage basins cover immense areas. Only four rivers—the Mississippi, Amazon, Congo, and Nile—surpass the largest rivers of Asia, the Yenisei and the Yang-tse-kiang, both as to length and drainage areas; but owing to the scarcity of rain over large parts of Asia, the amount of water carried down by the largest rivers is, as a rule, disproportionately small as compared with American or European rivers. The predominant feature of Asia's hydrography is the existence of very wide areas having no outlet to the sea. On the great plateau of Eastern Asia, the region which has no outlet from the plateau, and whose water does not reach even Lake Aral or the Caspian—the Han-hai and Gobi—covers a surface larger than that of Spain, France, and Germany together. It is watered only by the Tarim, which supplies some irrigation-works in its upper parts, and enters the rapidly drying marshes of Lob-nor. This area is steadily increasing, and since 1862 we have had to add to it the drainage area (as large as England and Wales) of the Keruleñ, which empties into Dalai-nor, but no longer reaches the Arguñ, a tributary of the Amur. The Ulyasutai River and the Tchagan-togoi now no longer reach Lake Balkhash; and the Urungu, which obviously joined the Upper Irtysh at no very remote date, empties into a lake separated from the Black Irtysh by a low isthmus not 5 miles wide. If we add, however, to this already wide area the drainage basins of Lake Balkhash with its tributaries, the Ili and other smaller rivers; the great Lake Aral, with the Syr-daria (Jaxartes) and Amu-daria (Oxus), as also the numerous rivers which flow towards it or its tributaries, but are desiccated by evaporation before reaching them; and finally the Caspian with its tributaries, the Volga, Ural, Kura, and Terek, we find an immense surface of more than 4,000,000 sq. m.—that is, much larger than Europe—which has no outlet to the ocean. Four inland drainage areas more must be added to the above—the plateaus of Iran and Armenia, two separate areas in Arabia, and one in Asia Minor, the whole representing a surface of 5,567,000 sq. m.
The drainage area of the Arctic Ocean comes next. It includes all the lowlands of Siberia, its plains, and large portions of the great plateau. The chief rivers flowing north to the Arctic Ocean are the Obi, with the Irtysh; the Yenisei, with its great tributary the Angara, which brings to it the waters of Lake Baikal, itself fed by the Selenga, the Upper Angara, and hundreds of small streams; and finally the Lena, with its great tributaries, the Vitim, Olekma, Vilui, and Aldan. Owing to their great tributaries, and still more to the fact that each of them is formed by two great rivers of nearly equal importance, they permit navigation to be carried on, not only north and south, but also west and east, over wide distances in Siberia (q.v.).
Three great rivers enter the Pacific, and all three are navigable for thousands of miles: the Amur, composed of the Arguñ and Shilka, and receiving the Sungari—a great artery of navigation in Manchuria—the Usuri, and the Zeya; the Hoang-ho; and the Yang-tse-kiang, the last two taking their rise on the plateau of Tibet. They permit freighted boats to penetrate from the seacoast to the very heart of China. The Cambodia or Me-khong, the Salwen, and the Irawadi, rising in the eastern parts of the high plateau, water the Indo-Chinese Peninsula. Rising on the same height, the Indus and the Brahmaputra flow through a high valley in opposite directions along the northern base of the Himalayas, until both pierce the gigantic ridge at its opposite ends, and find their way—the former to the lowlands of the Punjab, where it is joined by the Sutlej, and the latter to Assam and Bengal, where it joins the great river of India, the Ganges, before entering the Gulf of Bengal by a great number of branches forming an immense delta. The plateau of the Deccan is watered by the Godavari and Krishna, flowing east, the Narbada, flowing west, and a great number of smaller streams. The Tigris and Euphrates, both rising in the high plateau of Armenia, flow parallel to each other, bringing life to the valley of Mesopotamia, and join before entering the Persian Gulf. Arabia Proper has no rivers worthy of notice; only the wādyas, or dry channels of former rivers, show that there was a time, not far distant, when it was well watered. The Irmah, which enters the Black Sea, is the only river worthy of notice in Asia Minor. In Caucasus, the Rion and Kubañ enter the Black Sea, and the Kura and Terek the Caspian.
Inland Seas, Lakes.—Numberless lakes are scattered all over Asia. A succession of great lakes, or rather inland seas, are situated all along the northern slope of the high plateaus of Western and Eastern Asia, their levels becoming higher as we advance farther east. The Caspian, 800 miles long and 270 wide, is an immense sea, even larger than the Black Sea, but its level is now 85 feet below the level of the ocean; Lake Aral, nearly as wide as the Aegean Sea, has its level 157 feet above the ocean; farther east we have Lake Balkhash (780 feet), Zaisan (1200 feet), and Lake Baikal (1550 feet). Numberless smaller lakes and ponds, all rapidly drying up, break the surface of the steppes and lowlands of Siberia; while in the north, immense marshes cover the low grounds of Western Siberia. Many large lakes appear on the plateau of Tibet (Tengri-nor, Bakha) and on the high plateau of the Selenga and Vitim (Ubsa-nor, Ikhe-aral, Kosogol, Oron); and smaller lakes and ponds are so numerous that maps on a large scale are literally dotted with them. The same is true with regard to the plateau of the Deccan, Armenia, and Asia Minor. Three large lakes, Urmia, Van, and Goktcha, and many smaller ones, lie on the highest part of the Armenian plateau. On the Pacific slope of the great plateau, the great rivers of China and the Amur with its tributaries have along their lower courses some large and very many small lakes, which seem like reservoirs where the immense quantities of water carried down by these rivers during the summer rains is stored. The lakes Tun-ting, Po-yang, and Tai-hu, along the Yang-tse-kiang; those along the former course of the lower Hoang-ho; and Lakes Kizi and Hang-ka on the Amur and Usuri, as well as numberless smaller lakes, fall under this category.
Geology.—The time has not yet come when the geological history of Asia can be written in full. It appears, however, that the great plateaus, built up of crystalline unstratified rocks, granites, granitites, syenites, and diorites, as well as of gneisses, talc, and mica-schists, clay-slates and limestones, which all belong to the Archæan formation (Huronian, Laurentian, Silurian, and partly Devonian), have not been submerged by the sea since the Devonian epoch. The higher terrace of the plateau of Pamir and the plateaus of the Selenga and Vitim are built up only of Huronian and Laurentian azoic schists; and even Silurian deposits—widely spread on the plains—are doubtful on the plateaus. Their upheaval dates from an earlier age, and they rose above the sea during the Devonian epoch, while parts, at least, of the lower terrace were under the sea at that period. During the Jurassic period, immense fresh-water basins covered the surface of those plateaus, and have left their traces in Jurassic coal-beds, which are found as well in the depressions of the plateaus as in those of the lowlands. Carboniferous deposits are met with in Turkestan, India, and Western Asia; while in Eastern Asia the numerous coal-beds of Manchuria, China, and the archipelagos are all Jurassic. During the Cretaceous