If we enquire of the geologist the origin of these phenomena, we receive an answer which, while it leaves many points obscure and doubtful, still enables us to trace the operation of fixed principles in the mighty work unfolded before our eyes. Our globe sails through the wan expanse of æther, diffusing the heat with which it is charged. The cooling crust shrinks and gathers inwards towards the centre; but the material of which it consists is inelastic and is thrown into gigantic wrinkles or folds. Radial contraction induces tangential stresses at the surface, colossal forces which bend over and invert the folds, and even thrust the strata one beneath another, causing them to be disposed like the tiles upon a roof. This lateral tension finds most relief where the crust is weakest; and it is at such points, or along such zones, that the process of mountain-making has been developed on the largest scale. It is the tendency of such folded ranges to form arcs of large curvature, which are drawn inwards, where the lateral pressure meets with most resistance, and expand outwards, where it is withstood in a lesser degree.
In Asia the operation of this process of mountain-making has been accompanied by, or has produced, the elevation in mass of large portions of the earth’s crust. The intensely folded regions, or, in other words, the great chains of mountains, are found along the inner and the outer margins of the elevated mass. Between these zones the stratified rocks have no doubt been subjected to the folding process; yet they have escaped the immense contortions that have taken place on either side.
Throughout the continent the lateral force which has been most operative in mountain-making has proceeded from the north. The fact may perhaps be explained by supposing that this force is the result of the active pressure exerted by the hard, unyielding material of which the steppes of Siberia and the basin of the Arctic Ocean are composed. The great arcs which are described by the mountain ranges are in general convex to the south. Thus in western Asia the chains on the inner and outer margins of the elevated area are disposed in two roughly parallel series of arcs bulging towards the south. Of these series the inner arcs have less curvature than the outer, to which they are roughly parallel.
The inner series may be traced with greatest singleness of feature on the west of Hindu Kush—that natural centre of the mountain systems of Asia which at once supplies the most convenient standpoint for a general survey of the structure of the continent, and is placed at the junction of the two great divisions, western and eastern, into which geographers have partitioned this vast area. The Hindu Kush inclines over into the Paropamisus; and the southern portion of the latter range is continued, on the north of Persia, by the mountains of Khorasan. A sharp bend in the belt, just east of the Caspian, turns southwards into the Elburz range, and the beautiful curve of the chain along the margin of the shore may be admired from the waters of that inland sea. The line of Elburz is protracted across the depression of the Araxes valley into the peaks of Karabagh; while the Karabagh system unites with the bold and lofty ridges which in full face of their gigantic neighbour, the Caucasus, overtower the right bank of the Kur. These ridges again connect with the chain we have ourselves crossed between Kutais and Akhaltsykh—a chain which joins the mountains on the southern shore of the Black Sea. The Pontic range forms a bow of wide span and gentle curvature, ending in the hump of Anatolia, where it meets the arc of the Bithynian border hills.
The parallel series on the outer margin of the elevated area commences with the outer arc of the Hindu Kush system, the severely bent and S-shaped Salt Range. Thence it proceeds into the mountains which flank Persia upon the east and belong to the outer Iranian arc.[1] The bold sweep of this arc into the chain of Zagros may be recognised by a glance at the map. We remark the greater protraction of the north-western arm of the bow, a feature which may be traced in the configuration of most of the great Asiatic chains. We admire the clean and uniform outline of the curve, broken only by a slight indent at the straits of Ormuz, which may be answered by the bend in the inner system which we have already noticed on the east of the Caspian Sea. The outer Iranian arc effects a junction with the Tauric ranges along two parallel but fairly distinct orographical lines. Of these the inner line crosses over from the Zagros to the Ararat system, and assumes commanding orographical importance in the western arm of that system, known as the Aghri or Shatin Dagh. It is in the Shatin Dagh that the bend to the west-south-west is effected, which may be followed through a series of volcanoes into the Anti-Taurus and the Mediterranean range. The outer line is formed by the grand half-circle of the Kurdish mountains; from the parched plains about Diarbekr you see them, as from the well of an amphitheatre, covered or capped with gleaming snow. This principal chain of Taurus extends to the coast of Syria, and emerges from the sea in the island of Cyprus and in many a headland and island of the Anatolian coast.
It can scarcely fail to impress the most casual of observers that this double series of arcs, from Hindu Kush to Mediterranean, meet or almost meet at three distinctly traceable and widely separated points. Such approximations occur in Hindu Kush, in Armenia, and in the mountainous districts which border the Ionian seaboard. We can scarcely doubt that they are due to the incidence of a strong opposing force, moving from the south and causing the arcs to be constricted, the ranges to be piled up one behind another, and mountain development to assume its grandest forms. It is probable that the resisting pressure has been furnished in the first two cases by the Indian and Arabian peninsulas. Another feature, less obvious but not less noteworthy, is furnished by the fact that in Armenia and Asia Minor the arcs have been fractured in the process of bending over at or near the points where the approximations between the two series have taken place. The closer the constriction, the sharper, of course, becomes the curve, and the greater the tendency to split. In Asia Minor the union of the series has resulted in complete fracture; the folded area sinks beneath the waters of the Ægean to be represented by the islands which stud the Archipelago, and, further west, by the mountains of the Dalmatian coast.
On the east of Hindu Kush we are as yet in want of sufficient material for so convincing an analysis as the researches of geologists have rendered possible on the west. We know that in eastern Asia a vast area of elevated land is bounded both along the inner and the outer margins by mountain systems of wide extension and great height. Such are the systems of Altai and Tian-shan upon the north, and the mighty bow of the Himalayas on the south. Probably the Kuenlun range carries over the inner series of western Asia, extending eastwards from the Pamirs and serving as a buttress to the immensely elevated plateau of Tibet. If this view be correct, then the Tian-shan and Altai systems may perhaps be regarded as minor earth-waves, following close upon the heels of the Kuenlun, and supporting the highlands of the Tarim basin and the desert of Gobi, the Han-hai or Dry Sea of the Chinese. The plain reader may be content to observe the echelon of mountain ranges which extends from Hindu Kush towards Behring Sea; to note the constant curvature of the arcs towards the south, until, in the Altai group, the eastern arms of the bows are protracted ever further towards the north; to contrast the low-lying plains along the western ends of the echelon with the lofty highlands of Mongolia on the east. The necks of the valleys issue upon the depression of Siberia and the low country through which the Oxus and Jaxartes flow.
In western Asia the elevated area with its flanking ranges is bordered on the north by the northern Paropamisus and further west by the Caucasus chain. The Paropamisus may perhaps be regarded as the most southerly of the many branches which belong to the system of Tian-shan.[2] Geologists invite us to connect the Paropamisus with the Caucasus, and trace the links of the broken chain to the mountains of Krasnovodsk on the Caspian, whence a submarine ridge carries the line into the mountains of Caucasus, to be protracted far to the west, through the Crimea, and emerge from the waters of the Black Sea in the Balkans, Carpathians and Alps. In this manner we see described on the north of the Asiatic highlands, with their series of inner arcs, a further arc of immense span and wide curvature, which is represented on the east by the northern Paropamisus and by the Caucasus on the west. Both these ranges may best be viewed as independent of the inner series; but Paropamisus is closely adpressed to the inner arc of Persia, and Caucasus is joined at a single point to the series, namely by the Meschic linking chain. Lines of elevation, similar to that which we have traced from Paropamisus, may be discovered, although with less orographical distinction, proceeding westwards and struggling over towards Europe from the more northerly branches of Tian-shan; they are almost lost in the great depression of the Turanian lowlands, but they follow arcs of increasing width of span.
This interesting study of the structure of Asia, which is due to the researches of recent years, not only serves to explain the pronounced features of Asiatic landscapes, as integral members of a vast design, but also enables us to understand many of the movements of history and many of the phenomena of the human world.[3] India is enclosed on all sides by the sea or by the outer mountains, and appears reserved by natural causes for herself. China, with her teeming millions, is separated from western Asia by the whole bulk of the broadest and least hospitable portion of the system of lofty plateaux with peripheral ranges. The echelon of chains, which seam the continent in a north-easterly direction, are the nurseries of the hardiest tribes. The valleys which space these ranges are the arteries of human movement, and they lead from west to east, from east to west. Thus during the period of armed migrations which is represented by the Tartar conquests, one division of the Tartar armies might be fighting in China on the Yellow River while another was laying waste Khorasan. The bend of the arcs towards the south places the framework of Nature in harmony with the migrations of man. The tablelands of Persia, Armenia and Asia Minor are members of a continuous system of elevated plains at a temperate altitude, which extend like some great causeway along the breadth of Asia, giving access from east to west, from west to east. This causeway forms the natural avenue of commerce and of conquest, by which the tide of war or of commercial intercourse ebbs and flows between the remote recesses of Central Asia and the Ionian shore of the Mediterranean Sea. Only on the east is the causeway blocked by Nature to human traffic, by the constriction of the arcs on the north of India, leading over by a gigantic knot of mountains into the impassable plateau of Tibet. The stream is therefore diverted from the highlands to the lowlands; great cities arise on the lowlands, at the mouths of the Tian-shan valleys, Merv, Bokhara, Samarkand. And when we contemplate and contrast the structure of Asia and of Europe—the vast forces which have produced the stately body of eastern Asia dying out towards the west in the insignificant but widely ramified elevations of the European mountain chains—we may readily understand how different has been the influence exercised by structural features upon the peoples of either continent. In Asia such features are a factor of the first importance, determining climate, controlling migrations, setting barriers to intercourse or relentlessly fixing the highways which it must pursue. In Europe, on the other hand, they have done little more than diversify the scenery, and for purposes of peaceful or hostile movements among the nations may with some exceptions be almost left out of account. What are our European mountains but arbitrary wrinkles on the face of the continent? One valley leads over into another of much the same height above sea-level by a pass which is not more lofty than the neighbouring ridges. One plain is succeeded by a companion expanse of similar character, and only some small diversity in the forms of the spires of the churches tells the tale of national distinctions. Differentiation rather than the presence of marked ethnological types is characteristic of the peoples of Europe. But once the narrow strait is passed we may no longer dally with our geography; and the further we proceed towards the east and the inner sanctuaries of Nature the greater grows the necessity of comprehending phenomena which must always exercise a dominant influence upon human affairs. It will not suffice in Asia to observe the latitude of a great plain in order to know beforehand the degree of heat which it will support in summer, the rigour or the suavity of the climate during winter. You will be freezing in Erzerum while Erivan is relaxed in sunshine; yet both cities are placed on the margins of level expanses, and the advantage of latitude is in favour of the temperateness of that first named. Not even the convenient distinction of highlands and lowlands will carry us very far. We must enquire into the nature of the highlands; are the mountains their prevailing feature, or are those mountains, as we see them from the floor of the lowlands, a mere buttress to a sequence of elevated plains? Penetrate the chain, and you rise by successive steps from valley to valley, while each ridge is higher than the last. Follow its extension upon the map and you will see it rising from the Mediterranean and terminating in the knot of mountains north of India. Mark the characteristics of the people who inhabit it, be they Kurds or Lurs or Lazes, they will not offer much divergence from a common standard. Yet what a gulf of human nature between these and the inhabitants of the lowlands—a gulf which is scarcely spanned by the equalising tendencies of a long spell of misgovernment! When at length these alps expand, and you overlook a more level country, everything—climate, the aspect of the sky as well as of the land, people, language, cities, villages are new. And yet our diplomatists who dwell on the Bosphorus, and ruminate Asiatic problems with the aid of indifferent maps which they would not pretend to understand, group the highlands and the lowlands, the shepherds of the mountains and the cultivators of the plains, all together—a strange collection of birds and beasts and fishes—in a single scheme of administrative reforms. The Turk is little wiser; but we may perhaps view with a large indifference his passive resistance to such reforms.
But to return to our plains and mountains—the country which we may still call Armenia takes its place as an integral member of the system of tablelands, buttressed by mountain ranges, which extends from the Hindu Kush to the Mediterranean Sea. It is not separated by any important natural frontier from Persia on the east or from Asia Minor on the west. Moreover most of the characteristics which are found in either of these neighbours are prevalent in Armenia to a greater or a lesser degree. The stratified rocks include the later Palæozoic, the Cretaceous, Eocene and Miocene series; and these extend across the whole system. The salt deposits of Miocene age which are spread so widely over Persia are not among the least remarkable of the surface features of Armenia; although they have not produced that widespread devastation which attends the extension of the great salt deserts over the Persian plateau.[4] In Armenia they are friendly to man, providing him with one of his necessaries; and the various salt works, known in Turkey under the name of tuzla or salt pans, have been exploited from immemorial times. Considerable depressions of the surface of the highlands are phenomena common to all three countries; and the same may be said of the volcanoes which are dominant in Armenian landscapes, but are not wholly absent from the contiguous territories on either side. All participate in the benefits of a southern climate, and are exempted by their elevation above sea-level from the excesses of a southern sun. Slowly-flowing rivers threading vast plains, mountains which determine districts rather than states; a natural penury of vegetation, enhanced by the depredations of countless goats, but perhaps balanced in the eyes of the traveller by the beauty of the land-forms—such are some among the many impressions which may be derived in various degrees from a visit to any of the individual members of the group.