Mt. Hallasan is a shield volcano on Jeju Island of South Korea and is often taken as representing the island itself. The mountain which rises 1,950m above sea level is the highest mountain in South Korea. Mt. Hallasan is the product of the Quaternary volcanism (about 2.5 million years ago) in the Korean Peninsula and adjacent seas. A crater lake on the mountain called Baengnokdam along with the precipitous rocky cliffs and about forty parasitic cones, or oruem in the local dialect, provide spectacular landscape. The volcanic rocks around Baengnokdam were produced only tens of thousands of years ago. Because of its young age, the summit area of Mt. Hallasan preserves fresh volcanic landforms and rock formations. The summit of Mt. Hallasan provides different sceneries due to contrasting properties of two different lavas that formed the summit. The western side of the crater was made of highly viscous trachyte lava, forming a dome-like topography. The eastern side, on the other hand, was made from highly fluid trachybasalt lava, resulting in a gently sloping topography. Mt. Hallasan was designated as a natural monument in 1966 and a national park in 1970 because the mountain preserves the pristine morphology of a shield volcano unaffected by significant weathering or erosion. The mountain has been protected from human activity since then and is renowned for its unique ecology and biodiversity. The mountain was designated a UNESCO Biosphere Reserve in 2002 and a World Natural Heritage Site in 2007.