Do you know how Jeju island was formed ? If not, it’s a good chance to stretch your knowledge out !
Basically, Jeju island is formed from volcanic activity making it a very interesting island with its unique topological and geological features. Most Koreans have visited Jeju at least once, and if they haven’t, it is something on their list of must do’s.
Around 1.8 million years ago, the Earth was at its coldest temperature since the Paleozoic Era and the Glacial and Interglacial Periods repeated with a period of tens of thousands of years. From this climate change, the sea level repeatedly went up and down by 100m and the southern part of Korea became a plain and continental shelf 100m below the sea level. At the same time, hot hot magma under the southern continental shelf was ready to erupt along the cracks caused by crustal movements.
Around 1.6 millions years ago, the magma finally burst through the cracks and the erupted magma suddenly became cold and crushed in upon itself when meeting the sea in the south. Also, the sea suddenly evaporated and expanded, leading to strong explosion of hydromagmatic volcanoes. These hydromagmatic activities repeatedly occurredover almost one million years and as a result, numerous tuff rings and cones stacked layer by layer underneath Jeju and a volcano-based sedimentary layer called the Seogwipo Layer was formed.
About 600,000 years ago, as Jeju island already appeared well over the sea level, the hydromagmatic eruption began to diminish. The magma became red lava and started to repeatedly cover the Seogwipo Layer. Lava plateaus were created through numerous lava eruptions which mainly occurred in the center of the island. In that way, several tens of thousands years ago when neo-men appeared on the Earth , Halla mountain, the highest one in South Korea, was formed and Jeju island was in the final stage of formation.
In the mid-Holocene Era when the environment was similar to now, there was the last hydromagmatic eruption on the eastern part and south-western tip of Jeju, forming Seongsan Sunrise Peak and Songak Mountain. Jeju continued to have several other volcanic eruptions even in the Historic Age and making it the youngest island in Korea. Also it has a world-class volcanic landform.