In addition to serving as a political boundary, the Yalu River constitutes a dividing line between Chin.... feet river

In addition to serving as a political boundary, the Yalu River constitutes a dividing line between Chinese and Korean cultures. The Yalu rises in T'ien Lake (known in Korean as Ch'on Lake), a body of water of indeterminate depth on top of Pai-t'ou Mountain on the ChineseNorth Korean border, at a height of 9,000 feet (2,700 m) above sea level. Winding southward as far as Hyesan, North Korea, and then meandering northwestward for 80 miles (130 km), the river reaches Lin-chiang, Kirin province, from which it flows southwestward for 200 miles (320 km) before emptying into Korea Bay. Except for small areas of basaltic lava along the easternmost part of the river's course, the Yalu flows over Precambrian rock (more than 570 million years old) before its alluvium begins to spread out as it approaches its estuary. It is supposed that these tributaries once were connected with the Sungari River, a tributary to the Amur, only to be separated from it and connected with the Yalu when an! eruption of Pai-t'ou Mountain produced a flow of basaltic lava during the Quaternary Period (within the last 1.6 million years). Ever since a tribe called the Yojin was driven into Manchuria in the 16th century, the Korean side of the river has been inhabited only by Koreans. Rice is the main crop grown along the river's lower course; corn (maize), millet, soybeans, barley, and sweet potatoes are raised further upstream in the mountainous middle and upper reaches of the river. The river measures about 460 feet (140 m) in width and 3 feet (one metre) in depth at Hyesan and is 640 to 800 feet (200 to 250 m) wide and 4.5 feet (1.4 m) deep at Chunggang. In its estuary the river is 3 miles (5 km) wide and 8 feet (2.5 m) deep. feet river