VII. promontory of a continent, or with mountains on shore, may BOOK be considered as a continuation of the chain. Thus, it is evident, the Kurile islands connect Yeso or Jesso with Kamtchatka, in the same way as the great and small Antilles connect the two continents of America. But to make the observation hold, the intervals which separate the islands must either be very small, or be filled up with rocks and shoals beneath the surface, so as to preserve unbroken the continuity of the bases of these maritime mountains. Thus, the supposed connection between the Canary Islands, the Azores, and Mount Atlas in Africa, though possible, requires to be verified by repeated soundings, so as to discover the nature of the bottom of the intervening sea. Mountains, in general, have no precise and regular direction. The chains, sooner or later, bend and deviate into a curve, and frequently lose themselves in plateaus, or upland plains. seas. mountains, waters. We must not therefore give the reins to our imagination, Chains of and pretend to trace entire series of terrestrial and subma- and divirine chains, and thus form a frame-work for the globe, which sions of has no existence in nature.* It is not sufficient to see upon a map, that there is in a particular place a division in the There are many such divisions in the world, which afford no traces whatever of mountains, but only of extended plateaus, or upland plains, which rise with a gentle inclination on both sides, often for the space of a hundred leagues. We meet with no lofty mountains, but a collection of hills, in the centre of European Russia, although this is the centre whence some of the largest rivers of Europe diverge. Nay, there is actually in Russian Poland, between the Niemen and the Duina on one side, and the Dnieper and Dniester on the other, a point of division, which affords no sensible elevation whatever, and where, instead of the moun Ph. Buache, Essai de Geographie physique, dans les Mem. de l'Acad. des Sciences, 1752, p. 399.-Comp. Lehmann, Specimen chorographiæ generalis, tractus montium primarios sistens. Petrop. 1762. VII. BOOK tains laid down by Buache, travellers have discovered only a marshy plain. Even about the middle of the course of the Dnieper, there is a mountainous elevation, consisting of pebbles and shells, which that river passes through, following a deep fissure or glen, in which it runs.* On the other hand, the Niemen passes round some hills of Eastern Prussia, much more elevated than the point of division of the waters, as is shewn in Fig. 48, which is the profile of Europe, between the Baltic and the Black Sea. A total difference may be observed between this profile, and that which the same quarter of the world presents, bisected in the direction of the gulphs of Genoa and Hambourg, (Fig. 49.) and both these again form a contrast with that of the plateau of Mexico, (Fig. 50.) and of South America, (Fig. 51.) one of which is copied from the original, in the possession of M. Humboldt, and the other from a scale of heights, published in his travels. We may easily judge into what absurdities we may be led, should we have recourse to any general system whatever, for the purpose of discovering facts, of which observation alone can point out to us the astonishing variety. Submarine chains. The system of Buache has given rise to those chains of submarine mountains, which do not in fact exist, but which, nevertheless, make a figure in some theories of the earth. A detached island, a sand-bank, a reef of rocks at the surface of the water, are sufficient, in this author's opinion, to indicate a submarine chain, between two points of the world, however distant from each other. Nay, sometimes he has not deigned to assign any reason whatever for his conjectures. For example, he would represent Iceland, the Faroe Isles, and those of Shetland, as forming one submarine mountain between Greenland and Norway, notwithstanding that there is a deep sea between Norway and Shetland; and that from the direction of the mountains being parallel, and not converging, these chains could in fact * Hydrographical chart of Poland by Roustan and Komarzewski. Map of Rizzi-Zannoni. Notes by MM. Stibielowitz and Niemcewski of Wilna, VII. never coincide. Besides, the basaltic nature of Scotland, BOOK of Ireland, of Faroe, and of Iceland, seem to point out an ancient union of the British Islands with Greenland, rather than with Norway. In the same way, the submarine chains of the South Sea, have in general a direction quite different from that which Buache ascribes to them, according to the uncertain discoveries of his time. They have not the least connection either with Mexico or South America, any more than with the imaginary Austral continent. Many of these chains of islands, and particularly those which are the most insulated, have a very remarkable direction, but entirely opposed to the system of Buache; they extend from northwest to south-cast, in the direction of the magnetic axis of the earth. the moun Let us however examine, notwithstanding the erroneous General dihypotheses of our predecessors, whether we cannot introduce rection of general views more conformable to the truth, in our attempts tains of the to trace some sort of constant analogy, in the direction of the mountains of the two continents. If we draw a line from the centre of Thibet, across Chinese Mongolia, towards Okotsk, and thence towards Cape Tchutchi, or the eastern promontory of Asia, this line will in general coincide with an immense chain of mountains, which run from the south-west to the north-east, and every where descend very rapidly towards the Indian and Pacific Oceans; while on the other hand, they extend themselves towards the Icy Sea, in plains and secondary hills. It is probable that we may one day be able to reduce to the same rule, the chain of Lupata, called the "Spine of the world," which is situated in Africa; at least, the short chain from the Cape of Good Hope to that of Guardafui, in a direction of south-south-west, and of north-north-east, which is nearly the same direction as the great chain of Asia; but we are still ignorant of the declivities of these mountains. We may consider the lofty and steep mountains of Arabia Felix* as the link which connects the work. Seetzen, dans Zach. Astron. Corresp. xi. See "Arabia," vol. ii. in this earth. BOOK mountains of Lupata with the plateaus and mountains of Persia, on the side of Thibet. VII. Great chains of From Behring's Straits to Cape Horn, if we follow the western coasts of America, we shall find one unbroken chain of the highest mountains of our globe. This chain occasionally bends a little into the interior, but it more frequently closely borders the ocean, with a range of steep and bold shores, and sometimes with the most tremendous precipices. On the other side, the outlets of lakes, and the direction of the great rivers, evidently shew that nearly the whole surface of America inclines towards the Atlantic Ocean. It follows from these combined observations, that the the globe. greatest chains of mountains upon the face of our globe are ranged in a circle round the Great Ocean, and the Indian Sea; that they more frequently exhibit steep and rapid descents towards that immense basin, which they surround, and long and comparatively gentle declivities on the opposite coasts; that in short, from the Cape of Good Hope to Behring's Straits, and from thence to Cape Horn, the eye even of the most severe and scrupulous observer, cannot fail to discover some links of an arrangement, as astonishing from its uniformity as from the immense extent of country which it embraces. Let us stop here for a moment, and consider this great fact of physical geography. If we suppose ourselves placed in New South Wales, with our face turned towards the north, we shall see America on our right, Africa and Asia on our left. These continents, which, not long since, we could not even in imagination, consider as at all approaching each other, being examined from this point of view, form, as it were, one whole, the structure of which, as far as it is known, exhibits in its grand features a most amazing symmetry. A chain of enormous mountains surrounds a vast basin this basin, divided into two by a large mass of islands, frequently washes with its waves the base of this great primitive chain of the earth. But when did this immense chain of granite and porphyry shoot up from the bosom of the waters? Or when did those loftly secondary mountains sink into the depths of the ocean, and by their simultaneous submersion, form that steep and abrupt range of coast, which predominates over this globe? Shall we suppose that the earth was formerly, like the planet Saturn, surrounded by a ring, and that this celestial vault, losing its equilibrium,* was precipitated upon the surface of the earth? But to what length will imagination wander, emboldened by seductive, but vague and inconclusive analogies? Let us then return to the old continent, and recollect, that the vast regions of India and China, contrary to such analogies, are placed to the south of this great girdle of mountains; that the peninsula beyond the Ganges even joins that astonishing group of broken and intersected countries, which fill the centre of the great basin; and that this is as it were the link which connects with the present continent, those grand remains of a former continent, of a hemisphere, which seems to have disappeared. BOOK VII. inclination If again we consider under the same point of view the General whole extent of the two continents, which, in regard to the of contigreat ocean, is placed beyond this principal chain of the nents. globe, we shall perceive that the greater part of the plateaus, or upland levels, and of the chains of mountains, incline very generally towards the Atlantic and Northern Oceans. That extent of waters, vast as it is, appears then only like a canal, if we compare it with the great Pacific Ocean. The steep coasts which border the Atlantic, are nothing in comparison with those of the Cape of Good Hope and of Cape Gardafui, with the precipices which surround the seas of Kamtchatka, of Peru, and of Chili. of moun tains. We may expect, perhaps, to find likewise a certain Elevation general analogy among mountains, in regard to their height; but we must at once confess, that we are still less acquainted with the real height than with the direction of the principal chains of mountains. Our mea * Comp. Laplace, Syst. du Monde, 1. iv. ch. 9. p. 255, 3d edit. VOL. I. 23 |