LEBANON (Semitic laban, "to be white," or "whitish"), in its widest sense, is the central mountain mass of the State of Great Lebanon (proclaimed in 1920 in the French mandated terri tory in Syria), extending for about loo m. from north-north-east to south-south-west. It is bounded west by the Mediterranean, north by the Nahr el-Kebir, beyond which rise the mountains of the Ansariye, and east by the inland plateau of Syria. To the south the Lebanon mountains end where the River Litany bends westward. A structural depression followed in its southern sec tion by the Litany and in its northern by the ancient Orontes, divides the mountainous mass into two great parts. That lying to the west is still called Jebel Libnan; the greater part of the eastern mass is now called the Eastern Mountain (Jebel-esh Sharki). In Greek the western range was called Libanos, the eastern Antilibanos. The southern extension of the latter, Mount Hermon, may in many respects be treated as a separate mountain. The eastern boundary of the State of Great Lebanon passes over Mount Hermon, makes a detour around Zebdani and then follows the crest of Anti-Lebanon.
The district west of Lebanon, averaging about 20 m. in breadth, and composed in the main of Upper Jurassic and Upper Cretaceous rocks, slopes in an intricate series of plateaux and terraces to the Mediterranean. The coast is mainly abrupt and rocky, often leaving room for only a narrow path along the shore. Most of the mountain spurs run from east to west, but in northern Lebanon the prevailing direction of the valleys is north-westerly, and in the south some ridges run parallel with the principal chain. Most of the valleys have been deeply ex cavated by mountain streams as is typical of a limestone region ; the heights are crowned by lesser villages, castles or cloisters. The chief perennial streams include the Nahr Akkar, N. Arka, N. el-Barid, N. Kadisha, "the holy river" Wadi el-Joz (falling into the sea at Batrun), Wadi Fidar, Nahr Ibrahim, Nahr el-Kelb (the ancient Lycus), Nahr Beirut (the ancient Magoras, entering the sea at Beirut), Nahr Damur (ancient Tamyras), Nahr el-cAuwali (the ancient Bostrenus). The 'Auwali and the Nahr
el-Zaherani, the only other considerable streams before the Litany, flow north-east to south-west, in consequence of the interposition of a ridge subordinate and parallel to the central chain. On the north, where the mountain bears the special name of Jebel Akkar, the main ridge of Lebanon rises gradually from the plain. Valleys run to the north and north-east, among them that of the Nahr el-Kebir (anc. Eleutherus). The Berdani rises in Jebel Sunnin, and enters the Buka'a plain by a gorge at Zahleh.
The highest summits occur in the north. The "Cedar block" consists of a double line of four and three summits respectively, ranged from north to south with a general elevation just under ft. (Zahr el-Kazib, ft.). South from them is the pass (8,351 ft.) which leads from Baalbek to Tripoli S. Farther south is a second group of summits—the snow-capped Sunnin vis ible from Beirut (8,554 ft.). Between this group and the more southerly Jebel Kuneiyiseh (6,825 ft.) lies the pass (4, loo ft.) traversed by the road between Beirut and Damascus. Among the summits farther south are the ridge of Jebel el-Baruk (about 7,00o f i..), the Jebel Niha, with the Tamat Niha (6,070 ft.), near which is a pass to Sidon, and the Jebel Rihan (5,389 ft.).
The Buka'a, the valley which separates Lebanon from Anti Lebanon, is composed mainly of recent deposits flanked by the limestones on the west and Eocene rock followed by the Upper Cretaceous of Anti-Lebanon on the east. It is watered by two rivers having their watershed near Baalbek, at an elevation of about 3,60o ft. That flowing northwards, El-tAsi, is the ancient Orontes (q.v.) ; the other is the Litany. In the lower part of its course the latter has scooped out a deep and narrow bed in typical limestone country. It bends suddenly westwards over the Cretaceous rocks. Near the bend are the ruins of the old castle of Kalcat esh-Shakif. In its lower part the Litany bears the name of Nahr el-Kasimiyeh.