ANNAMESE CORDILLERA

French Chane Annamitique, Vietnamese Truong Son principal mountain range of Indochina and the watershed between the Mekong River and the South China Sea. It extends parallel to the coast in a gentle curve generally northwest-southeast, forming the boundary between Laos and Vietnam. A fairly continuous range for about 700 miles (1,100 km), its rather precipitous eastern slopes leave a narrow coastal plain. Although its highest peak, Mount Linh, is only 8,524 feet (2,598 m) high, the range has few substantial passes, the most important being the Keo Nua Pass in northern Vietnam, part of a route between Muang Khammouan, Laos, and Vinh, Vietnam, and the Mu Gia Pass (q.v.). The geologically complex range is constituted mainly of limestones, sandstones, granites, and gneisses in the north and in the south an exposed, folded crystalline basement overlain in several places by basaltic lava flows. Among the plateaus created by these flows are the Bolovens Plateau in southern Laos and the Kontum and Dac Lac plateaus in southern Vietnam. To the south, the Annamese Cordillera begins to reverse itself, reaching 7,500 feet (2,300 m) or higher in peaks west of Nha Trang before terminating in the Saigon plain of southern Vietnam.