Caucasus, a general name given to the region and the chain of mountains therein which stretch between the Black and Caspian seas, the mountains forming part of the boundary between Europe and Asia. The region traversed by the range diagonally from N. W. to S. E. forms the Russian lieutenancy of Caucasia. It lies between lat. 38° 50' and 46° 30' N., and lon. 37° and 50° 30' E. Its longest diameter, N. W. to S. E., is about 800 m.; area about 170,000 sq. m.; pop. in 1867, 4,661,824. It is divided into the following governments and districts: Kuban, Stavropol. Terek, Daghestan, Zakatal, Titlis, Kutais, Sukhum, Tchernomore (Black Sea), Elizabethpol, Baku, and Erivan. The first five, which lie in Europe, are called Ciscaucasia, and embrace, among others, the territories of the Kuban and Nagai Cossacks, the Kabarda, the Tchetchna, and the land of the Lesghians; the last seven lie in Asia, are designated as Transcaucasia, and include Cir-cassia, Abkhasia, Mingrelia, Imerethia, Georgia, Russian Armenia, and Shirvan. An outline of the central part of the country would represent a system of round-topped mountains, exhibiting few of those peaks which distinguish the Alpine and other chains, their sides seamed with deep but fertile valleys, descending to the steppes or plains which stretch N. into the main country of the Cossacks, and S. E. toward Persia. The Caucasus range commences in a line of cliffs fronting on the Caspian sea, at the peninsula of Apsheron, whence the main chain stretches in a N. W. direction to the shores of the Black sea, a distance of 700 m., and terminates in the promontory where the sea of Azov unites with the Black sea, near the Russian fortress of Anapa. From the main chain other ranges branch N. and 8., giving the hill country a width of from 65 to 150 m.

The principal subsidiary chains are on the north. The principal summits are Mount Elbruz or Elburz, on the N. E. confines of Abkhasia, 18,514 ft. high; Kasbek, W. of the road from Mozdok to Titlis, about 16,500 ft. (like the preceding, first ascended by three young English tourists, Freshfield, Tucker, and Moore, in July, 1868); and Syrkhubarsom, between Elbruz and Kasbek, about 15,600 ft. The passage of these mountains is effected through defiles, some of which have a historic celebrity. Such are the Caucasian, now called the Darial pass or pass of Vladikavkar; the Albanian or Sarmatic pass in Daghestan; and the Iberian, now called the Sharapan pass, in Imerethia. Only one road is practicable for carriages, that from Mozdok to Tiflis, by the Darial pass and the valley of the Terek. The mountains of the Caucasus are either fiat or round-topped. The geological structure of the greater portion is of secondary formation, interspersed with volcanic rocks. The summits and central ridge are granitic; on each side the granite has schistose mountains joining it, and these are succeeded by calcareous hills whose bases are covered by sandy downs. The mountains are more abrupt on their north face; southward they descend by a succession of terraces.

Snow rests on summits over 11,000 ft. in altitude throughout the year. The glaciers are but of limited extent, and no active volcanoes are known. Earthquakes occur. There are few lakes. Twelve watersheds or channels are counted, six on the X. slope, and six on the S. The principal rivers on the northward are the Kunia and the Terek, flowing E. to the Caspian, and the Kuban, W. to the Black sea. On the S. the Kur (the Cyrus of the ancients) flows E., and the Rion (Phasis) W. - The country of the Caucasus possesses every variety of climate, from the arid heats of the valley to the cold of perpetual snow. Vegetation in the habitable districts is luxuriant. Forests of the finest timber clothe the hills almost to the snow line. Grain will grow at an elevation of 7,000 ft. In the central belt the ordinary species of fruits produce well. Dates, pomegranates, and figs ripen in the valleys. Rice, flax, tobacco, and indigo are sure crops. The culture of sugar cane, silk, and cotton has been introduced into some localities. The tea plant has been recently introduced at Sukhum Kaleh, on the Black sea.

Among the productions peculiar to the Caucasus are a species of cochineal insect; a hard-wood tree called locally utchelia, with wood of a rose color, suitable for cabinet work; also the Caucasian goat, celebrated for the value of its hair; and a wild animal of the feline species, called by the natives chaus. The horses of the Caucasus bear a high character for endurance and docility. Wild cattle are found in the forests. Wolves, bears, jackals, lynxes, and the minor fur-bearing animals, are numerous. The wool of the ordinary breeds of sheep is long and fine. Almost every species of birds known to the latitude are found here. Few minerals have been discovered; gold appears to be totally wanting; iron, copper, saltpetre, and lead are found, the last in considerable quantity. - The Caucasians proper, including Circassians, Mingrelians, Ab-khasians, Ossetes, Tchetchentzes, Lesghians, Grusians, and many other tribes, of Indo-European race, are generally a bold and resolute people, hunters, robbers, and guerillas from choice, shepherds and agriculturists only from necessity. Although hospitable, they are jealous and revengeful. They live in villages built of stone. Formerly their youth of both sexes were raised for sale in the slave markets of Constantinople; but that traffic has been suppressed.

Their political organization was formerly a loose sort of republicanism, under the nominal presidency of a hereditary prince; but tho rule of Russia is now firmly established over them. Literature they have none. Their religion is an offshoot of Mohammedanism, corrupted from many sources. - Ancient history makes frequent mention of the Caucasus. Here Prometheus was chained. Deucalion, Pyrrha, and the Argonauts, Sesos-tris and the Egyptians, the Scythians, Mithri-dates, Pompey, and Trajan are associated with its history. The Arabs, Tartars, and Turkomans successively ravaged the country to its base. Russia and Persia then struggled for its possession, until in 1813 the Russians, after having occupied Mingrelia, Imerethia, and Georgia, became nominally possessed of the S. E. parts of the mountains by treaty. A desultory warfare of several years ended by the mountaineers being reduced to a condition nearly approaching subjection. But in 1823 a new movement sprung up in the mountains. Mohammed, the mollah, commenced against the Russians a campaign in Daghestan. A chieftain named Kasi-Mollah was soon recognized as the head of the movement, having for his aid a young man named Shamyl. In 1829 the N. W. portion of the mountains fell into the hands of the Russians by the treaty of Adrianople, but the Circassians soon rose in arms against them.

The various tribes now united in resistance, but the Lesghians and Tchetchentzes bore the brunt of the struggle. Kasi kept up a resistance to the Russian power till 1831, when he was shut up in Himry. The Russians stormed the place, and the chief was slain. Ilamsad Bey next took the field, but his career was cut short by assassination. The mollah Mohammed being now dead, Shamyl was elected his successor, and carried on the war with varying success. In 1837 Shamyl inflicted a severe defeat on the Russians under Gen. Ivelitch. During 1838 the Caucasians were employed in preparing themselves for future resistance. The passes of the mountains were fortified, and the strong position of Akulgo was put in readiness to stand a siege. In 1839 the Russians, under Gen. Grabbe, entered the territory, defeated the Caucasians, and drove them back upon Akulgo, which was finally taken, Aug. 22, after a blockade of 72 days, and three days' hand-to-hand fighting. The Caucasians once more nominally succumbed to the Russian power, but in March, 1840, they again revolted. Having found European tactics ineffective in the previous campaign, they fell back on their old system of guerilla warfare. Gen. Grabbe again attempted to penetrate into the mountains, but was compelled to retreat.

The next attempt was made in 1845 by Prince Vorontzoff, governor general of the Russian Caucasian provinces. He penetrated to Dargo, which he found in flames. The campaign being over, a new plan of action was introduced against the mountaineers. Hitherto the tactics had been to bring them to pitched battle, with the hope of breaking their strength at a single blow. Now the plan was to send detached columns against isolated spots, and wherever a footing was obtained to erect a fort on it. Notwithstanding this, the Caucasians continued to carry on offensive operations. In 1846 they swept the line of Russian forts, and returned to their mountains laden with plunder. In 1848 and 1850 they made similar expeditions, and in 1853 they took from the Russians several guns, and drove them back from eight . leagues of territory. During the Crimean war there was a pause in the operations in the Caucasus. In 1856 the Russians opened a war-tare, which they continued till April, 1859, when the capture of the stronghold of Veden virtually decided the contest. Shamyl retreated to his last stronghold, the mountain fort of Ghunib, near the Caspian sea.

Here, on Sept. 6, he was defeated after a desperate conflict and forced to surrender, and was carried a prisoner to Moscow and St. Petersburg, but treated with the utmost consideration. The Caucasus had in many parts become desolate. The bulk of surviving Circassians emigrated to Turkey. (See Shamyl.)