Few great mountain chains have their boundaries so clearly marked by nature. On the N. it is bounded by the' vast plains and steppes of Russia, which extend completely across from the Sea of Azoff to the Caspian, and are carried up to the very foot of the mountain slopes; on the S. it is bounded at first by the Black Sea, for a distance of nearly 240 miles, and afterwards by the broad and level valley of the Rion as far as Kutaïs, about 70 miles inland. Farther eastward the valley of the Kur may be considered as forming its southern limit from the neighbourhood of Tiflis to the Caspian, a distance of more than 250 miles. But between the towns of Kutaïs and Tiflis the country is more broken, the underfalls and minor ramifications of the Caucasus extending to the south so as to meet those of the mountain chain which forms the southern boundary of the valley of the Rion. The two ranges are, indeed, united at this point by a transverse range of very moderate elevation, which forms the watershed between the streams that flow into the Black Sea, and the Kuι and its tributaries, which flow eastward towards the Caspian. This dividing range (commonly known as the mountains of Suram from the town of that name) may therefore be regarded as con stituting a connecting link between the Caucasus and the southern range, which extends from the Black Sea in the neighbourhood of Poti to that of Tiflis, and itself attains to a very considerable elevation, several of its summits having an altitude of from 9000 to 10,000 feet. But these ranges belong to the great mountain group of Armenia, and are inseparably connected with the mountains of Lazistan, and with those which extend inland to join the northern branches of the Taurus; and they cannot with any propriety be regarded as forming part of the system of the Caucasus. The transverse range above described, though forming the watershed between the two basins of the Rion and the Kur, is in itself but an inconsiderable ridge of hills, and the point where it is traversed by the high road between Kutaïs and Tiflis has an elevation of only about 3000 feet above the sea. Hence the Caucasus may properly be considered as forming an isolated chain, unconnected with any other of the great mountain systems of Asia; while those to the south of it belong in reality to the widespread ramifications of the range known to the ancients as Mount Taurus, which extends from Asia Minor through Armenia into Persia.

It is unfortunate that some modern geographers, especially Germans, have introduced into their systematic treatises the practice—first adopted by the Russian residents in the provinces south of the Caucasus—of designating these southern ranges by the appellation of the Little Caucasus, a term tending to produce confusion, and to encourage the notion of their being connected with the great northern range in a manner which is certainly not the case in any true orographical sense. In the present article the name of the Caucasus will be employed only as applied to the great mountain range which, as has been already stated, forms a continuous barrier from the shores of the Black Sea to those of the Caspian, and to which alone the appellation has been applied from the time of the Greeks to our own day.

The origin of the name is unknown. It was employed by the Greeks in very early times, and has continued in use among geographers ever since. But no general name for the whole chain is known to the tribes that inhabit it, or to those that immediately adjoin it. Nor does it appear that any of the local or native designations of portions of the mountains known by this name are such as may reasonably be supposed to have given rise to the term.

At the present day the line of the Caucasus is generally regarded as constituting the boundary between Europe and Asia; and though it is only in quite modern times that this line of demarcation has been established among geographers, it is so much the most convenient natural limit that it can hardly fail to continue to be received. as such. The scientific conclusion has, moreover, been confirmed of late years by the official sanction of the Russian Government, which has adopted the watershed or central ridge of the Caucasus as the line of separation between its European and Asiatic provinces.

In its general character and conformation the range of the Caucasus may be considered as presenting more analogy with the Pyrenees than with the Alps. Its general uniformity of direction, its comparatively small width, and its well-defined limits towards both the south and the north, are strong features of resemblance to the former, rather than to the latter, of these well-known ranges. To these it may be added that, like the Pyrenees, the ridge of the Caucasus generally preserves for long distances together a high average elevation, and is not broken by those deep depressions, constituting natural passes across the chain, which are of such frequent occurrence in the Alps. Another point of resemblance between the Pyrenees and the Caucasus is to be found in the fact that in both cases two of the highest summits are in some measure detached from the main range; and just as the Mont Perdu and the Maladetta both lie south of the central ridge of the Pyrenees, and are consequently distinctly included in Spain, so Mount Elbruz aud Kazbek—the two best known summits of the Caucasus—are situated decidedly north of that chain, and must therefore be geographically assigned to Europe, if the line of demarcation be drawn along the watershed of the range. Both these mountains are, in fact, of recent volcanic origin, and, geologically speaking, unconnected with the granitic masses which constitute the central axis of the chain.

It had long been known that the highest summits of the Caucasus exceeded the most lofty of the Alps in positive elevation; but until very recently no accurate measurements of them existed, and little or nothing was known of any of the individual peaks except the two already mentioned. Of these Mount Elbruz owes its celebrity not merely to the fact that it is in reality much the most lofty summit of the whole range, attaining an elevation of not less than 18,526 feet, but to the circumstance that from its partly isolated position, it is conspicuously seen, both from the Black Sea and, on the other side, from the plains and steppes of Russia, where it is said to be distinctly visible from a distance of more than 200 miles. Kazbek, on the contrary, attracted attention from an early period, on account of its proximity to the Pass of Dariel, in all ages the only frequented pass across the range of the Caucasus. Hence it was long supposed to be the second in height of the whole range, which is now found not to be the case, though it attains an elevation of 16,546 feet, or nearly 800 feet higher than Mont Blanc. But between these two giant peaks rise those of Koschtan Tau and Dych Tau (both of the names until very recently quite unknown), of which the former rises to nearly 17,100 feet, while the latter attains to 16,925 feet; these are therefore entitled to rank as the second and third summits of the Caucasus, while Kazbek can claim only the fourth place. It is, indeed, doubtful whether some of the other peaks on the great snowy range do not also exceed it in height.

For the purpose of description it may be convenient to divide the great range into three portions.

1. The first of these, comprising the western portion of the mountain chain, begins in the neighbourhood of Anapa on the Black Sea, where it rises at first merely as a chain of hills of moderate height, but gradually assumes more and more of a mountain character, until the highest summits attain to an elevation of 9000 to 10,000 feet. It is not, however, till they approach the neighbourhood of Elbruz that they pass the limit of perpetual snow; but the central chain, from the 4lst degree of longitude eastwards, is almost constantly'covered with snow, and throughout the greater part of the year exhibits a lofty range of snow-clad peaks, that can find no parallel in Europe, except in the Alps. Throughout this western portion of the Caucasus, the central chain forms a very distinct line of watershed, at no great distance from the Black Sea, but gradually receding from it, and thus leaving a wider interval between its shores and the main ridge. Even at Sukhum Kaleh, however, in longitude 41°, the central chain of the mountains is not more than 30 miles inland in a direct line as measured on the map. The whole of the intermediate space is filled up by the underfalls and subordinate ranges of mountains thrown out from the great chain, extending for the most part quite down to the sea, so as to constitute a coast line of a singularly rugged and inaccessible character. For a distance of nearly 200 miles from Novo Rossisk to Sukhum Kaleh there is nothing like a harbour, while the dense forests with which the mountains are still covered contribute to render the interior impassable.

From the proximity of the central ridge to the sea, in this western portion of the Caucasus, it naturally follows that no rivers of any importance are to be found on the southern slope of the mountains, though it is furrowed by numerous mountain torrents, which add to the impracticable character of this part of the country. On the northern side, on the contrary, the mountains slope more gradually towards the plains of Russia, and here several considerable streams are found, all of which pour their waters into the Kuban, which itself takes its rise in the glaciers of Elbruz. Among the most considerable of these streams may be mentioned the Urup, the Laba, and the Bjelaia.

2. The great central mass of the Caucasus, extending from the neighbourhood of Elbruz to that of Kazbek, or from the source of the Kuban to the pass of Dariel, a distance of about 130 miles in a direct line, is at once the most important and interesting part of the whole chain, and is that which has of late years been the most fully explored It is here that are found all the most lofty summits of the whole range. Besides the four above mentioned, there are at least five other peaks in this part of the chain that attain to not less than 15,000 feet, viz., Gumaran Khokh and Adai Khokh, which, according to the Russian survey, measure respectively 15,672 and 15,244 feet in height, while three others, not found in the survey, are estimated by the practised English mountaineers as follows :— Tungzorun, 15,000 feet; Tau Tötönal or Tetnuld, 15,500; and Uschba (one of the most remarkable mountains in the whole of the Caucasus), not less than 16,500 feet. But it is not merely that isolated summits attain to these great altitudes, but the whole line of the watershed or central ridge, from a point south of Elbruz to the group of Adai Khokh, on the west of the Ardon valley, is an uninterrupted line, which nowhere sinks below 10,000 feet, and is traversed only by glacier passes, some of them extremely rugged and difficult, others comparatively easy, but still presenting an extent of snow and ice equal to that of the well-known pass of St Theodule in the Alps. There is here, therefore, an unbroken mass of glacier and perpetual snow of nearly 100 miles in length, or as far as from Mont Blanc to the St Gotthard. It nowhere, however, attains to any great width, nor do any of the glaciers that descend its flanks equal in extent the largest of those in the Alps. Eastward of the Adai Khokh group the ridge is intersected by the upper valley of the Ardon, but the range of snowy peaks is continued after this interruption by the lofty summits of Tau Tepli and Gumaran Khokh on to Kazbek, where the whole chain is deeply cut through by the gorge of Dariel, and the corresponding depression of the pass between Kobi and Mleti. But while the series of peaks just referred to may be considered as the continuation of the true axis of the chain, the watershed, which has for so long a space run nearly from W.N.W. to E.S.E., bends suddenly due south, and sinks to the comparatively low gap of the Mamisson Pass, which is about 9400 feet in height, and entirely free from glacier. After a few miles it resumes its former direction, but without recovering its elevation or grandeur, the peaks of this part of the chain rising only to 11,000 and 12,000 feet, while the passes which traverse it range from about 9000 feet to less than 8000 feet, the elevation of the Krestowaja Gora, where the watershed is traversed by the high road from Vladikafkaz to Tiflis. In this part of the chain, therefore, we have a watershed of comparatively small altitude, with a parallel range to the north of it of much more lofty mountains. The central mass, on the contrary, from Elbruz to Adai Khokh, presents a lofty medial range of granitic structure, on both sides of which, but especially on the south, rise secondary chains of limestone mountains, preserving in a general way parallel courses with that of the main chain. Hence the upper valleys are troughs, bounded on both sides by lofty mountains, through which the upper waters of the streams that take their rise in the glaciers of the central chain are compelled to flow, until they make their escape by deep gorges cut through the lateral ranges. The most important of these parallel trough-like valleys is the upper valley of the Ingur, forming the district known as Suanetia, which is between 40 and 50 miles in length, and will thus bear comparison with the two great valleys of similar structure in the Alps, the Valais and the Valteline.

It may naturally be expected that so great a mass of glaciers and perpetual snow should send forth a number of considerable streams, and in fact all the principal rivers of the Caucasus have their sources in the district now under consideration. Commencing with those on the south side of the chain, which flow towards the Black Sea, we find —(1.) the Kodor, a considerable stream, which enters the sea about 12 miles south of Sukhum Kaleh; (2.) the Ingur, a much more important river, which rises in the great glaciers of the Central Caucasus, near a place called Jibiani, and, after flowing for nearly 50 miles in a course parallel to the great chain (as already described) and receiving in its course the outflows of numerous other glaciers, turns abruptly to the south-west, and after pursuing that direction for above 60 miles, discharges its waters into the Black Sea at the little town of Anaklia; (3.) the Zenesquali, which rises in the mountains almost immediately east of the sources of the Ingur, and in like manner flows at first nearly due west, then turns towards the south-west and south, and joins the Rion about 30 miles above its mouth at Poti; and (4.) the Rion itself, the most important of all the Caucasian rivers that flow into the Black Sea. The Rion has a very circuitous course, having its source at the foot of the mountain called Pasi Mta, very near the sources of the Zenesquali, and flowing at first in a southeasterly direction, past the little town of Gebi, about 8 miles below which it receives an affluent from the Mamisson Pass towards the north-east; it then turns about south-west till it has passed the village of Oni, after which it flows for a considerable distance (above 30 miles) nearly due west, through one of the parallel valleys above described, and then again turns due south until it has passed under the walls of Kutaïs, the capital of Imeritia. A few miles below that town it emerges from the hills into the broad and level valley that separates the underfalls of the Caucasus from the ranges to the south. It here receives a tributary called the Quirilha, which brings down the waters from the Suram range (the transverse ridge that unites the Caucasus with the mountains of Armenia), and then again turning to the west, pursues a winding course, but retaining the same general direction, till it enters-the Black Sea at Poti, about 50 miles in a direct line from its junction with the Quirilha. The Rion is in the lower part of its course a deep and rapid stream, and is navigable for steamers as high as Orpiri, where it receives the Zenesquali, but unfortunately a shallow bar at its mouth prevents the entrance of large steamers from the sea. It is the river so well known in ancient times under the name of Phasis, and connected by Greek legends with Medea and the voyage of the Argonauts.

All the streams that take their rise on the southern side of the Central Caucasus, east of the Mamisson Pass, are tributaries of the Kur, and discharge their waters into that river, which itself, however, does not derive its origin from the Caucasus, but flows from the mountains of Armenia, and receives its first Caucasian affluent, the Lachwa, at the town of Gori. The most important of these tributaries is the Aragwa, which has a course almost due north and south, from its source above Mleti to its junction with the Kur at Mscheti. It is up the valley of this river that is carried the highroad from Tiflis to Vladikafkaz, which turns off at Mleti to cross the pass of the Krestowaja Gora, and from the natural facilities afforded by this line of route, it has been from the earliest ages frequented for the same purpose.

The rivers that flow from the Central Caucasus northwards have much longer courses than those on the south side, both from the more gentle slope of the mountains in that direction, and from the extent of the steppes beyond, through which they have afterwards to find their way to the sea. By far the most important of these rivers are the Kuban and the Terek, which receive as tributaries all the minor streams. Of these the Kuban takes its rise in a glacier at the foot of Mount Elbruz, immediately below the watershed of the main chain. It flows at first in a northerly direction, and preserves this course till it has altogether quitted the mountains, and entered the steppe of the Nogai Tartars, when it trends first towards the north-west and then abruptly towards the west, which general direction it pursues till it enters the Sea of Azoff by one mouth and the Black Sea by another. Its whole course is estimated at above 400 miles. During the latter part of its course, from east to west, it receives the waters of all the smaller streams that descend the northern slopes of the Western Caucasus. The Terek has its source in the central chain, where it issues from a small glacier at the foot of Zilga Khokh, its head waters being separated from those of the Ardon only by a pass of moderate elevation. Its upper valley, like so many others, has a direction parallel to the main range, so that it is compelled to flow towards the south-east as far as the village of Kobi, where it turns to the north-east, which direction it holds to the village of Kazbek, and from thence pursues a course almost due north, traversing the famous ravine or gorge of Dariel, until it finally issues from the mountains at Vladikafkaz. From thence it takes a north-westerly direction, which it follows for a distance of more than 70 miles, receiving on its way numerous affluents, the last of which is the Malka, after its junction with which, near the town of Jekaterinograd, it turns abruptly to the east and pursues its course in that direction through a tract of steppes and marshes for 200 miles to its...