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Mountains and Hills
Korea's territory coincides with the Korean Peninsula. Between the peninsual and Manchuria flow, in opposite direction, the two largest rivers of the region, the Amnokkang (Yalu) and Tuman-gang (Tumen) both originating at Mr. Paektusan (2,744 meters), the highest mountain throughout Korea and Manchuria. The other three sides of the peninsula are surrounded by the Yellow Sea, the East Sea and the South Sea, respectively.
Nearly 70 percent of the Korean Peninsula is covered by mountains and hills. Located mostly in the southern and western regions, these hills give way gradually to increasingly higher mountains toward the eastern and the northern end. On the whole, the western and southern slopes of the peninsula are wide with some plains and basins along rivers, while the eastern slope is very narrow because the high mountains hug the East Sea coastline.
Most of the high mountains are located along the T'aebaeksan range which parallels the east coast, running roughly north-to-south. West of this range are the drainage basins of the Han-gang and Kumgang rivers. This range is extended to the Nangnimsan range in North Korea, forming the geological and geomorphilogical backbone of the peninsula and constituting the drainage divide between the western and eastern slopes of the peninsula. Mr. Nangnimsan (2,014 meters), Mr. Kumgangsan (1,638 meters), Mr. Soraksan (1,708 meters) and Mr. Taebaeksan (1,567 meters) are some of the highest summits along these ranges. Just southwest from the T'aebaeksan range is another important range, the Sobaeksan, which culminates in the massive Mr. Chirisan (1,915 meters). This range was historically a great barrier between the central and southern parts of the peninsula, and also between the eastern and western regions in the south. The Naktonggang river basin is thus segregated in southeastern Korea. The so-called "Roof of Korea," the Kaema Plateau, located in the northwestern corner of the peninsula, has an average elevation of about 1,500 meters above sea level.
The landmass of the peninsula is rather stable geologically in spite of its proximity to Japan; it has neither active vocanoes nor strong earthquakes. There are, however, a few extinct volcanoes that have been formed during Pleistocene. Mr. Paektusan is famous for a large caldera lake, "Ch'onji," meaning "Heavenly Lake." Mr. Hallasan in Chejudo island, the highest mountain in South Korea, was reorrded to have minor volcanic activities in the early 11th century. It has a small crater lake, "Paengnoktam," and there are about 4000 parasitic cones in its piedmont.
About two-thirds of the Korean Peninsula is composed of pre-Cambrian metamorphic and granitic rocks. Although the distribution of sedimentary rocks are very limited, limestone is quite abundant in some regions and a number of limestone caves have developed, some of them attracting tourists. Among the most famous caves are Kossigul, Kosugul and Songnyugul, all of which are decorated with stalagmites and stalagtites.
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RIVERS AND PLAINS
Most of the major rivers flow into the Yellow Sea and a few into the South Sea, draining the western and southern slops of the peninsula. Considering its areal size, Korea has a relatively large umber of large-sized streams, six of them exceeding 400 kilometers in length. The discharge of rivers fluctuates very much due to the summer monsoon. In the summertime, rivers swell with heavy rainfalls, often flooding valley plains every once in a while. In other seasons, relatively dry, the water level drops to very low levels and often much of the river beds is exposed. Typhoons, which hit the southern part of the peninsual once every two or three years, also bring heavy rainfalls in late summer and early autumn.
Most of the plains are narrow floodplains developed along rivers, especially in the lower reaches. These plains are the major rice-producing landforms. Large tidal ranges at the mouths of major rivers flowing in to the Yellow Sea inhibited the development of deltaic plains, although rivers transport large mounts of sediment during floods. Only the Maktonggang river flowing into the South Sea has a small delta at its mouth. Erosional basins along rivers in areas of granitic rocks have also been important as agricultural regions since ancient times. Many large cities such as Ch'unch'oon, Ch'uongju and Wonju are located in such basins.
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Korea has a long coastline compared to its land area, and coasts are divided into the east, west and south coasts. The easst coast has small tidal ranges, a third of one meter at the most, and a relatively smooth shoreline with few islands offshore, because the T'aebaeksan range runs closely along the East Sea. Where mountains protrude from the T'aebaeksan range, coasts are rock in general, but some beaches are found in places into which small streams carry sediment from the high mountains. In many instances, the beaches take the form of sand pits and bars enclosing lagoons, which are notable features of the east coast. Along the coast between Wonsan and Kangnung are located a series of lagoons, of which Kyongp'o and Hwanjinpo are among famous resorts of the east coast. Since the highway connecting Kangnung and Seoul has been built in the 1970s, the east coast has been attracting tourists throughout the year, especially during the summer season.
The shorelines of the south and west coasts are very irregular with innumerable small peninsulas and bays as well as a large of number of islands. The west coast facing the Yellow Sea, which is very shallow, has large tidal ranges, above 10 meters in places. Harbors have been developed with difficulty because of large tidal ranges. Tidal flats are common coastal features especially in bays into which rivers discharge sediment during floods. Tidal flats have been reclaimed from ancient times mainly for rice fields, but since the 1970s, the reclamation of tidal flats has entered a new era in terms of magnitude. The Saemangum Project, which is under construction at present as the largest such project ever undertaken, seeks to reclaim a total of 40,100 hectares of the flats with a length of 33 kilometers of huge dikes to be completed early in the next century.
The south coast shows a typical ria shoreline, a coastal zone which has been submerged. The length of coastline is nearly eight times longer than its straight line distance, and its indentation is far greater than that of the west coast. The tidal ranges are relatively small with two to five meters, and tidal flats are not as wide as along the west coast. Although mountains face the sea, there are few beaches and sea cliffs along the mainland coast, because innumerable islands prevent the penetration of waves from offshore. Narrow straights between the mainland and islands are associated with extremely rapid tidal currents. At Ultolmok toward the western end of the south coast, tidal current reaches up to 13 knots.
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Information provided by the Korean Embassy