Jeju Yongcheondonggul Lava Tube Revealed

A 200m long and 6-10m wide lake illuminated like an emerald when a cave-exploration light shone down a dark cave 15m from ground level around 4:00 p.m. on October 15. This is the “Yongcheondonggul Lava Tube,” part of the Geomunoreum Lava Tube system, which was designated as a World Natural Heritage site by UNESCO in June.

Most unusually, Yongcheondonggul Lava Tube is also decorated with numerous carbonate formations. Calcite is precipitation from calcium and carbonate ions which are leached from overlying carbonate dune sands. In the cave, a wide range of calcite formations including soda straws, stalactites, stalagmites, columns, and rimstones can be found. It is estimated that Yongcheondonggul , or Yongcheon Cave, was created between about 100,000 – 300,000 years ago and the carbonate formations from about 2,600 years ago.

Jeju Province revealed the Yongcheondonggul Lava Tube to the press for the first time since its discovery in 2005 to celebrate its designation as a UNESCO World Natural Heritage. Some pieces of earthenware, animal bones, charcoal etc. within the lava tube show that humans lived there, yet when and how humans came to live there remains a mystery.

Dr. Choi Don-won, a speleologist from the Jeju Cultural Properties Committee, said, “A more comprehensive survey is needed for climatic condition and biota along with the carbonate formations.”

Dangcheomuldonggul near Yongcheondonggul was also made public for the first time on the same day since 1995. It is relatively short at 100m in length, but a variety of lava formations were found including stalagmites and stalactites.

jy788@donga.com