Caucasus, a great mountain-range that forms the backbone of a well-marked geographical region, nearly corresponding with the Russian governor-generalship or lieutenancy of Caucasia. It occupies the isthmus between the Black Sea and the Caspian, its general direction being from west-north-west to east-south-east. From the peninsula of Taman on the Black Sea, to the peninsula of Apsheron on the Caspian, it has a length of about 750 miles. The breadth, including the secondary ranges and spurs, is about 150 miles, but that of the higher Caucasus does not exceed 70 miles. This range is sometimes treated as the boundary line between Europe and Asia, but the region is really Asiatic in character (see Asia, p. 52). The higher and central part of the range is formed of parallel chains, not separated by deep and wide valleys, but remarkably connected by elevated plateaus, which are traversed by narrow fissures of extreme depth. The highest peaks are in the most central ridge or chain, at least six of them well over 16,000 feet, much exceeding the highest Alps. Mount Elburz attains an elevation of 18,538 feet above the sea, Dikh-tau of 16,923, and Kazbek of 16,541. Here the line of perpetual snow is between 10,000 and 11,000 feet high; but the whole amount of perpetual snow is not great, nor are the glaciers very large or numerous. For more than 100 miles' length of the main ridge there are no passes lower than 10,000 feet. The spurs and outlying mountains or hills are of less extent and importance than those of almost any other mountain-range of similar magnitude, subsiding as they do until they are only about 200 feet high along the shores of the Black Sea. Some parts are entirely destitute of wood, but other parts are very densely wooded, and the secondary ranges near the Black Sea exhibit most magnificent forests of oak, beech, ash, maple, and walnut; grain is cultivated in some parts to a height of 8000 feet, while in the lower valleys rice, tobacco, cotton, indigo, etc. are produced. The climate, though generally healthy, is very different on the northern and southern sides of the range, the vine growing wild on the south. The south declivity of the mountains towards Georgia presents much exceedingly beautiful and romantic scenery.

There are no active volcanoes in Mount Caucasus, but every evidence of volcanic action. Elburz and Kazbek are both of volcanic origin. There are hot springs and mud volcanoes at each end of the range, and there are also famous petroleum wells in the peninsula of Apsheron (see Baku). Mineral springs also occur in many places, notably at Vladikavkaz. The bison, or aurochs, bears, wolves, and jackals are among the animals. Lead, iron, sulphur, coal, and copper are found.

The waters of the Caucasus flow into four principal rivers - the Kuban and the Rion or Faz (the Phasis of the ancients), which flow into the Black Sea; and the Terek and the Kur, which flow into the Caspian. Kuban and Terek are north, Rion and Kur or Kura south of the mountains. The Russians have with great labour carried a military road through the tremendous fissure or ravine of the Dariel gorge, about halfway from the Black Sea to the Caspian. The road passes over a height of about 8000 feet, and is protected by many forts. The only other road is by the Pass of Derbend, near the Caspian Sea. The term ' Caucasian' was at one time used for all the finer types of the fair-skinned division of mankind, but the ' Caucasian race' of Blumen-bach has long been divided into the two groups, Aryan or Indo-European and Semitic; and it is very doubtful if the most of the Caucasian peoples belong to either of these stocks. The Ossetes, numbering perhaps 120,000, are distinctly Aryan; the southern or Kartveli group of Caucasian tribes (including the Georgians), the eastern group (including the Tchetchens and Lesghians), and the western group (including Circassians and Abkhasians), speak languages mutually unintelligible and of doubtful affinities.

The resistance which the Caucasian peoples for more than half a century offered to the arms of Russia attracted to them the attention of the world. But with the capture in 1859 of Shamyl, the prophet chief of the Lesghians, the power of the Caucasians was shattered; by 1870 it was completely broken. The bulk of the Circassians and Abkhasians migrated to Turkish territories in Asia or Europe. The ancient divisions of the country, Georgia, Imeritia, Svanetia, Mingrelia, etc, based on tribal distinctions, have disappeared from the Russian administrative system, in which the main range of Caucasus divides the province into Ciscaucasia, north of the mountains, and Transcaucasia to the south of them; the former comprising the governments of Stavropol, Kuban, Terek; the latter, those of Daghestan (really north of Caucasus), Tiflis, Kutais, Elisabetpol, Baku, Kars, and Erivan. Total area, 30S,000 sq.

m.; pop. 6,290,000. The chief town in Ciscau-casia is Vladikavkaz; in Transcaucasia, Tiflis. The old capital of Georgia was Mtzkhet, a good specimen of a Georgian word. See works by Freshfield(1869), Cuninghame(1872), Bryce(1878), Phillipps-Wolley (1883), 'Wanderer' (1883), and Abercromby (1890).