Jeju Volcanic Island and Lava Tubes show the geological history of the planet. Formed by volcanic eruptions, Jeju Island is full of a number of unique volcanic topography and beautiful scenery.
Hallasan Mountain is a typical example, which is 1,950m high and a volcanic mountain in the center of Jeju Island. A crater lake, called Baengnokdam, is at the summit, and there are various kinds of volcanic topography such as columnar-jointed cliffs and parasitic volcanos formed by the rapid cooling of lava. In addition, since the mountain covers from low to highland, its ecosystem is widely diverse. The area of Hallasan Mountain is preserved as a national reserve. Another example is the Geomunoreum (456m) and lava tube caves. In Jeju Island, there are 368 small-sized parasitic volcanoes, which are called ‘Oreum’ in the dialect of Jeju. The Geomunoreum is located in the northeast of Jeju. The lava that erupted from the Geomunoreum flowed along the surrounding areas creating a series of lava tubes such as Manjanggul, Gimnyeonggul, Bengdwigul, Dangcheomul Cave, Yongcheon Cave, etc. Each cave is unique and varies from each other in length, structure, and components. The last example is the Seongsan Ilchulbong (179m) located in the eastern end of Jeju, created by volcano eruptions under the sea. Its crater is huge with 570m of diameter and 90m of depth. The outer wall around the crater is very steep, and clearly shows the internal structure of the volcano due to the erosion of waves, which is very important to understand the formation process of a volcano.
‘Hallasan Mountain Natural Reserve’, ‘Geomunoreum Lava Tube System’, and ‘Seongsan Ilchulbong Tuff Cone’ are the typical examples of various volcanic topography in Jeju Island. It is the only place in the world where such diverse volcanic topographies are shown in a small-sized area. Jeju Volcanic Island and Lava Tubes are valuable Korean heritages that show the geological history of the Earth.